BYTE Magazine Volume 06 Number 09 - Artificial Intelligence

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In The Queue

Volume 6, Number 9

September 1981

Features

27a Look at NCC '81 by Steven K

Roberts / A photo essay on the National Computer Con-ference held last May in Chicago.

SO Build an Unlimited-Vocabulary Speech

Synthesizer by Steve Garcia /An easy-to-use speech syn-thesizer can be designed using the Votrax SC-01 Speech Syn-thesizer Chip.

5oThe Xerox Alto Computer by Thomas A

Wadlow / Some attributes of this research tool will be used inthe next generation of personal computers.

# 2 Tree Searching, Part 1: Basic Techni-ques by Gregg Williams / A BASIC program allows yourcomputer to solve a sliding-blocks puzzle.

112 One Step Forward—Three StepsBackup, Computing In the US Space Program

by Patrick Stakem / The stringent demands of spaceexploration are met by several 8- and 16-bit microprocessors.

1 64 Artificial Intelligence by Steven K

Roberts / Intelligent computers could ease the task of dealingwith vast amounts of information, if certain problems can besolved.

1 80 A High-Level Language Benchmark by

Jim Gilbreath / Speed benchmarks for more than fifty imple-mentations of high-level languages.

2wU Science Fiction's Intelligent Computers

by Donald Byrd / Current knowledge of artificial intelligenceputs science fiction to the test.

216 Symbolic Differentiation a la LISP by

Ronald L Nl'COl / The list-manipulation abilities of LISP areeasily adapted to differentiating mathematical functions.

238 Knowledge-Based Expert SystemsCome of Age by Richard O Duda and John G

Gaschnig / If an expert can do a specialized, self-containedtask, so can a program.

284 The Atari Tutorial, Part I: The Display

List by Chris Crawford / The display list allows you to

mix both text and graphics on the same video-display screen.

3U4 Natural-Language Processing, The

Field In Perspective by Gary Hendrix and Earl

Sacerdoti / Systems that interact in English must have some understanding of human psychology and the world outside the computer.

414 The Emperor's Old Clothes by Charles

Antony Richard Hoare / Mr Hoare, winner of the 1980ACM Turing Award, reflects on his career and speculates on thefuture.

Reviews

52 The Big Board: A Z80 System in Kit Form by DavidThompson

1 46 Misosys Software's DISKMOD: Put Radio Shack'sEditor/Assembler on Disk by Steve Hughes

1 50 MINCE, A Text Editor by Christopher O Kern

384 BYTE's Arcade: Big Five Software by Gregg Williams;The Prisoner by Bob Liddil

388 Three Microcomputer LlSPs by Steven P Levitan andJeffrey G Bonar

436 Interactive Fiction: Six Micro Stories by Bob Liddil

Nucleus

6 Editorial: Odds and Beginnings10 Letters34, 108 Book Reviews: Principles of Artificial Intelligence;

Turtle Geometry110, 383, 412 BYTE's Bugs162 Programming Quickies: Changing a BASIC FOR . . . NEXT

Loop into a REPEAT . . . UNTIL Loop354 BYTELINES360 Ask BYTE364 Books Received366 Clubs and Newsletters372 Event Queue383 Software Received412, 425 BYTE's Bits426, 428, 435 Technical Forum: Microcomputers and the

IRS; Add Dual Trace and Delayed Sweep to Your

Oscilloscope; How to Build an Inexpensive Cassette Level

Indicator432 System Notes: An Almost Optimum Z80 Memory Test

Program441 What's New?

494 Unclassified Ads

495 Reader Service

496 BOMB, BOMB Results

BITE

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September 1981 © BYTE Publications Inc 3

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Advertising

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Officers of McGraw-Hill Publications Com-pany: Paul F McPherson, President; ExecutiveVice Presidents: James E Boddorf, Gene WSimpson; Group Vice President: Daniel AMcMillan; Senior Vice President-Editorial: RalphR Schulz; Vice Presidents: Kemp Anderson,Business Systems Development; Robert B Doll,Circulation; James E Hackett, Controller; Eric BHerr, Planning and Development; H JohnSweger, Marketing.

Officers of the Corporation: Harold WMcGraw Jr. President, Chief Executive Officerand Chairman of the Board; Robert F Landes,Senior Vice President and Secretary; Ralph JWebb, Treasurer.

In This Issue

Computerized natural-language processing is one of the many topics thathave come to be associated with artificial intelligence. As Robert Tinney'scover suggests, computers someday may be able to read and understand Warand Peace. Steven Roberts' article "Artificial Intelligence" is a good place tostart, and "Natural-Language Processing, The Field in Perspective," by GaryHendrix and Earl Sacerdoti, addresses this month's theme. Donald Byrddiscusses the point at which fact meets fiction in "Science Fiction's IntelligentComputers," and Ronald L Nicol focuses on the artificial intelligence communi-ty's primary language in "Symbolic Differentiation a la LISP."

Steve Ciarcia has prepared an alternate way of eliciting speech from a com-puter with "Build an Unlimited-Vocabulary Speech Synthesizer." We alsohave a description of the Xerox Alto computer by Thomas A Wadlow, and wetake a look at NASA's high-flying computing machinery in Patrick Stakem's"One Step Forward—Three Steps Backup."

BYTE is published monthly by BYTE Publications Inc. 70 Main St, Peterborough NH 03458, phone (603)924-9281, a wholly-owned subsidiary of McGraw-Hill, Inc. Address subscriptions, change of address. USPS Form3579, and fulfillment questions to BYTE Subscriptions, POB 590, Martinsville NJ 08836. Controlled circulationpostage paid at Waseca, Minnesota 56093 - USPS Publication No. 528890 (ISSN 0360-5280). Canadian secondclass registration number 9321. Subscriptions are S19 for one year, S34 for two years, and S49 for three years inthe USA and its possessions. In Canada and Mexico, S2I for one year, S38 for two years, S55 for three years. $43for one year air delivery to Europe. S35 surface delivery elsewhere. Air delivery to selected areas at additionalrates upon request. Single copy price is S2.50 in the USA and its possessions, S2.95 in Canada and Mexico, $4.00in Europe, and S4.50 elsewhere. Foreign subscriptions and sales should be remitted in United States funds drawnon a US bank. Printed in United States of America.

Address all editorial correspondence to the editor at BYTE. POB 372, Hancock NH 03449. Unacceptablemanuscripts will be returned if accompanied by sufficient first class postage. Not responsible for lost manuscripts orphotos. Opinions expressed by the authors are not necessarily those of BYTE. Entire contents copyright © 1981by BYTE Publications Inc. All rights reserved. Where necessary, permission is granted by the copyright owner forlibraries and others registered with the Copyright Clearance Center (CCC) to photocopy any article herein for thebase fee of S1.00 per copy of the article or item plus 25 cents per page. Payment should be sent directly to theCCC, 21 Congress St, Salem MA 01970. Copying done for other than personal or internal reference use withoutthe permission of McGraw-Hill is prohibited. Requests for special permission or bulk orders should be addressed tothe publisher.

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Editorial

Odds and Beginnings

by Chris Morgan, Editor in Chief

As I sat down to write this month's editorial, I realized I was going to have ahard time sticking to one topic. So much has been going on lately, I thought I'dthrow it all into one convenient column. The title "Odds and Beginnings,"which I stole from James Thurber, reflects this potpourri.

Artificial Intelligence

I'm particularly pleased that we were able to fit so many interesting articlesabout artificial intelligence into this month's issue. Many of them were com-missioned at last year's AAAI (American Association for Artificial In-telligence) meeting at Stanford. In particular, the articles "Natural LanguageProcessing: The Field in Perspective" (page 304) and "Knowledge-Based ExpertSystems Come of Age" (page 238) discuss topics that, in my opinion, have notreceived the coverage they deserve. A personal computer's ability to under-stand at least rudimentary English will be important to the future of program-ming. Similarly, a computer that can give advice and act as an "expert" on agiven topic raises some profound and difficult questions. Some of these issueshave been dealt with in science fiction, and Donald Byrd explores them in"Science-Fiction's Intelligent Computers" (page 200).

Computer Shows

I've been on the road quite a bit this spring and summer attending computershows. As always, the West Coast Computer Faire in San Francisco was ofgreat interest. Anyone doubting the vitality of our field need only walk intothis show to be struck by the level of enthusiasm. If you want to track theprogress of personal computing, go to the West Coast Computer Faire andwatch the number of exhibitors expand and the wide-eyed visitors becomemore wide-eyed each year.

The NCC (National Computer Conference) was held in Chicago this year,and it was easily the most spectacular show yet. (See the two-page photo essaybeginning on page 36.) The "star" of the show, attracting a constantenthusiastic crowd, was the Xerox Star terminal, which single-handedlyadvances the state of the art in terminal design for the office. Many of thesystem's features recall those of the Smalltalk systems (see last month's BYTE,devoted to the Smalltalk-80 system) I saw at Xerox PARC (the Palo AltoResearch Center). The Star system, which will cost $16,595 for the standardunit, treats all documents, files, etc as concrete "objects" that can bemanipulated by the user. Its software structure resembles a nest of boxes, eachbox containing more and more complex information about the workings of thesystem. Users need penetrate only to the box they require to do a particularjob, thus avoiding information overload.

Clever user-interfacing devices abound on the Xerox Star, including a"mouse," a mechanical box with wheels that can be rolled around on thedesktop to position the cursor on the screen. I could go on at length about thefeatures of the machine, but I must move on. An excellent treatment of theStar can be found in the April 27, 1981, issue of the Seybold Report, a twice-monthly report that consistently offers the field's best coverage of word pro-cessing, computerized typesetting, and office automation. The report costs

Editorial continued on page 10

September 1981 © BYTE Publications Inc

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Editorial.

$175 a year, and subscriptions are available by writingBox 644, Media, Pennsylvania 19063.

In contrast to the Star, the recently unveiled Xerox 820personal computer (see page 441) is disappointing. It's acompetently designed machine but very "plain vanilla,"sporting a Z80 processor, CP/M, two 5V4-inch floppydisk drives (which give the user a paltry 92 K bytes ofunformatted storage per floppy disk), and no high-resolution graphics. What the 820 does do, however, isgive Xerox a foot in the door of the under-$3000 market.And one cannot deny the importance of the 820's abilityto interface with the Ethernet system, Xerox's informa-tion network that will most likely become the standardfor high-end local networks. We'll have more informa-tion about the 820 in upcoming issues.

Japanese Market

Senior Editor Gregg Williams and I recently spent tendays in Japan attending the Tokyo Microcomputer Showand visiting more than ten companies that produce, orare about to produce, personal computers. The level ofinterest in the microcomputer in Japan is astounding, andthe trip was a revelation. We will be reviewing many newJapanese machines and analyzing their effects on theAmerican marketplace in a special issue of BYTE toappear early in 1982. Watch for it. In addition, we will

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The question of the hour seems to be "Are the Japanesegoing to dominate the American personal computermarket?" My immediate answer is "No." It takes time todevelop distribution networks and become established inthis highly technical market—it's not the same as theautomobile market. But if ever I had any doubts that theJapanese had entered our field in earnest, the doubts weredispelled during the trip. Yes, the Japanese face manyobstacles. In order to create word-processing software,they need more familiarity with our typewriter-dominated office systems and more sensitivity to the needfor good software and good documentation. I have nodoubt that the Japanese will surmount these obstacles,and in fact they are quietly doing just that. According toan old Japanese saying, "It is the wise hawk that hides itstalons." The talons are now hidden, but they will comeout in time.

Coming Up

The coming year is going to be exciting at BYTE. We'reexpanding our staff to be more responsive to our readers.I'm pleased to say that BYTE's circulation has topped the200,000 mark and continues to climb rapidly. Weappreciate your feedback, especially in the form ofBOMB votes for your favorite articles. (See the readerservice card at the back of the magazine for an explana-tion of BYTE's BOMB.)

One of our major projects this year has beentransforming onComputing magazine into Popular Com-puting, a new monthly magazine that will appear thisNovember. It's designed for the nonspecialist and willcover the entire spectrum of popular computing for thebenefit of professionals, business people, educators, andinterested laypeople. We're particularly proud of the newPopular Computing staff stationed around the country tokeep readers up to dale.

What's in store for the coming year? We'll havecoverage of the new personal computers from the bigmainframe companies, plus special issues about humanengineering, interactive videodisks, computers inbusiness, local networks (next month), computers in thehumanities, games, computers for the disabled, andmuch more, including our extensive review section forhardware and software.

Incidentally, I took a look at the new computer sciencebooks that have come in for review. They make astultifyingly large pile, and the stack of new software isn'tmuch smaller. But we're working to keep ahead of thegame.

Another perennial interest at BYTE is computergraphics. By the time you read this, I will have attendedthe ACM's SIGGRAPH conference in Dallas. Watch for afull report featuring some of the most exciting graphicswe've ever seen.B

10 September 1981 © BYTE Publications Inc

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Letters

MIT Defends Logo Policy

This is in response to Mr Stephen Hain'sletter, which appeared in the August 1981BYTE and which raised questions aboutthe release and distribution of the MITApple Logo programming language. (See'Unpublished Apple Logo," page 32.)

As correctly noted in the original BYTEarticle ("Logo for Personal Computers,"by Harold Nelson, June 1981 BYTE, page36), the development of the MIT AppleLogo programming language was spon-sored in part by the National ScienceFoundation (NSF). Discussions betweenMIT and NSF with respect to mechanicsof release and distribution have beenunderway. Licensing authority has nowbeen formally requested by MIT; and, assoon as permission is granted, it is the in-tention of MIT to complete licensing ar-rangements that will ensure the broadestpossible dissemination of this importantprogramming language.

Kenneth A Smith

Associate Provost

MIT

545 Technology Sq

Cambridge MA 02139

Comments onSoftware Piracy

The following comments by our readerswere solicited through Chris Morgan'sMay 1981 BYTE editorial "How Can WeStop Software Piracy?"

I commend Chris Morgan and BYTE foraddressing a subject too frequently over-looked. Software piracy has, indeed,reached an appalling level, while some-how retaining an odd sort of tacit protec-tion—that of being a "gentleman's" crime.

Chris Morgan's statement that "soft-ware piracy ... is not just illegal—it'sunethical" couldn't have been more to thepoint. It is unethical. Shamefully so. Tothose who attempt to protect their works,this can't be stressed enough. The courtsand various legal bodies are slow, butthey are working toward resolving someof the piracy problems. Many talentedpeople are working madly devising clevertricks to prevent the theft—all becausethere are those who think it's better tohave something for nothing than it is toethically exchange with those who

worked hard to produce something ofvalue.

No doubt the thieves have justified theiractions. Maybe they think the "system" isunfair; maybe they think they can't affordthe programs they so dearly want; maybethey don't even think at all. But one thingis certain: they haven't developed soft-ware packages themselves and then hadthem ripped off to the tune of thousandsof dollars. That much we know.

It's a shame that one's fellow man iscalled upon to police another. One wouldlike to believe that we're fair and honestpeople. It appears not all of us are. Hence,in addition to the efforts of our legislatorsand programmers, those ethical souls wholearn of piracy need to do something ef-fective about it. If simple reasoning with asoftware pirate won't do it, then reportingthe matter to the developer just might.While contrary to the childhood dictum"don't be a tattletale," it could help to cur-tail a growing cancer in the industry.

The Association for Software Protec-tion (ASP) is a newly formed group dedi-cated to eradicating the piracy problem.At present it is addressing—in themain—the problems faced at the mini-computer level. Nevertheless, the piracyproblem branches across all levels, andany group or individuals interested inorganizing an antipiracy microcomputergroup are invited to contact ASP.

In addition to my activities with ASP, Iam the Software Protection Director atMini-Computer Business Applications inGlendale, California.

Robin RobinsonAssociation forSoftware Protection10143 Leona AveTujunga CA 91042

Chris Morgan's and BYTE's concernwith software piracy is well placed, andBYTE's coverage is excellent, but there arewider perspectives to add.

For millennia, humanity moved aroundpicking and chasing things to eat. TheAgricultural Revolution meant the com-plete transformation of social arrange-ments, which resulted in the invention ofprivate property, towns, political institu-tions, writing, ruling classes, fortifica-tions, the ownership of land, etc.

Things were like that for a few millen-nia more. For the last couple hundredLetters continued on page 18

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Your money buys you more becauseHeath/Zenith prices are among the industry's mostcompetitive. Make your own comparison and find outhow much you can save.

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18 September 1981 © BYTE Publications Inc

Letters.

years, however, most people have runmachines. As we see and know, everysociety and culture in the world has beenthrown into turmoil because, once again,the world is changing rapidly.

"Classic" economics is based on ma-terial commodities: if there are you andme and a loaf of bread, either you get it,or I get it, or we split it. No existing schoolof economics, however, deals with thefact that if you give me some information,you still have it. Material commodities get"thinner" when spread out, while infor-mation gets "thicker" as it's spread out.

Two-thirds of the jobs in the UnitedStates are informational. Money, proper-ty, and many other foundations of societyhave begun transmuting. Software piracyis a logical area for difficulties to emergefirst. Where else can you go into businessselling pure thought?

The more we are aware, and the morewe examine and discuss the big implica-tions, the less surprised we'll be.

Neil Rest1457 GregoryChicago IL 60640

Congratulations to Chris Morgan forhis timely attention to the software-piracycontroversy. The following specificationsmay be useful in evaluating solutions pro-posed for this problem:

• There shall be no realistic means fordefeating the protection mechanism, re-gardless of the attacker's technicalsophistication or familiarity with thedesign of the software-protection system.

• The software product shall not have tobe customized for each licensee.

• The user shall have to purchase one, andonly one, hardware device to use all pro-tected software. Once this device is at-tached to the computer, the user shall beable to forget it exists.

• The device shall be the same, regardlessof the computer system with which it isused; and it shall be compatible with ex-isting computer systems.

• There shall be no degradation of thereliability or versatility of a computersystem as a result of this device.

• The cost of the device shall be minorcompared to the cost of the least expen-sive (but practical) system on which pro-tected programs will be used.

• The logistical support of the protectionsystem shall require no effort on the partof the software publisher.

• The system shall restrict the use of pro-tected software to the licensed user for alicensed period of time.

I would appreciate the comments ofBYTE's readers on the applicability andcompleteness of these specifications. AtSalcris Corporation, we are currentlyfield-testing our Chrono-Guard SoftwareProtection System, which meets thesespecifications. Software protection is ouronly business and, while we believe wehave a carefully thought-out solution tothe industry's problems, we value con-structive criticism.

Thomas C Donald

President

Salcris Corporation

1 Office Park Cr

Birmingham AL 35223

In the May 1981 BYTE there wereseveral excellent articles on what I regardas one of the most severe problems facingthe computer-software industry today—theft of software. (See Chris Morgan's"How Can We Stop Software Piracy?",page 6; Christopher Kern's "WashingtonTackles the Software Problem," page 128;and Stephen Becker's "Legal Protectionfor Computer Hardware and Software,"page 140.) I know of several companies,mine included, that will not sell packagedsoftware because of the theft problem.The constant "reinvention of the wheel"that results from the reluctance to sellsoftware is one of the leading factors con-tributing to the already poor productivityof the industry. If we are not to stagnateand allow foreign competition to steal oursoftware lead, an early solution to thisproblem must be found.

One article mentioned several rathercomplex hardware solutions that are cur-rently proposed to help solve the prob-lem. While most of the hardware dis-cussed would provide more or less proces-sor-independent solutions that would re-quire no industry-wide effort to help solvethe problem, I feel that these efforts willlead to an expensive and relatively inse-cure solution. The cheapest and mostreliable answer is not a hardware solution(although hardware must play a key role),but "self-protecting" software.

How can software be made to protectitself? Well, I am not aware of any proces-sor on which this is possible today, but aminor processor modification could easi-ly, cheaply, and effectively accomplish

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Letton

this. The biggest problem will be to geteveryone to cooperate and adopt a stan-dard approach.

IBM was on the right track to solvingthe problem several years ago, but some-one, somewhere, dropped the ball, andthe solution became only half-imple-mented. Anyone who has ever done somesystems programming work on an IBMS/370 is probably aware of the privilegedinstruction "STORE PROCESSOR ID."This instruction provides systems pro-grams with the processor serial numberand other system information, such aswhether VM/370 is the system-controlprogram, etc. This instruction providessystem-level programs (and evenmicrocode) some degree of theft protec-tion, although its primary purpose is toprovide a method by which system pro-grams can determine what model pro-cessor is being used. The big problemfrom the applications program side,which is where IBM left the scene, is thatthere is no easy method to access the in-formation provided by this instruction.

To solve the software-theft problem,the entire industry must provide somemethod by which the user's applicationprogram can determine such informationas the make, model number, and serialnumber of the host processor. Additional-ly, it must be constructed in a mannersuch that it would be next to impossiblefor the user to modify the factory-sup-plied information. The addition of one in-struction to the processor repertoirewould undoubtedly increase the cost ofthe hardware, but the increase would noteven approach the price of the cheapestprotection method that I have seen pro-posed. The only disadvantages to this ap-proach are that it would not be easily ap-plicable to existing systems (most ofwhich will probably not be around morethan five years anyway, so why worry7)and it would preclude the distribution ofsource code (you would not want some-one to discover how you encrypt the pro-cessor ID and check against the licensedprocessor ID).

I welcome any comments.

Jon R Kibler

President

Southeastern Computer Services Inc

POB 160124

Mobile AL 36616

Chris Morgan's May 1981 BYTEeditorial mentioned a software-protection

20 September 1981 © BYTE Publications Inc

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scheme based on encrypting programs.

Since mid-1979, all Sentinel computershave used a somewhat more convenientscheme. In our systems (based on one ormore Intel 8086s), the machine's serialnumber is available to the operating sys-tem. The operating system recognizes en-crypted application programs and uses theserial number as a key to decrypt them asthey are loaded from floppy-, Win-chester-, or bubble-memory-disk storage.

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We also give Sentinel distributors thetools to encrypt their own programs.

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I read Chris Morgan's editorial on soft-ware piracy with interest. The two sidesof the software protection/duplicationcontroversy were drawn as "the vendor'sneed for security" versus "the user's needfor backup copies for reliability."

My experience with software products,both large and small, has revealed an evengreater need on the part of software pur-chasers than that of backup copies. Thisneed is for modifiable and configurablesoftware. A few years ago, most small-computer systems were either home-builtor installed and used without modifica-tion from the time they left the factory. Inthe case of personal computers, peripher-als were few and were usually made ordistributed by the frame manufacturer.Things are different today—and this hasgiven rise to the need for user-configur-able software.

For example, my firm's Apple II com-puter contains interface cards for fourperipheral devices: the disk system,printer, modem, and an 80-column videocard. Only one of these is an Apple Com-puter product. Nearly every softwareproduct we have purchased has requiredreconfiguration—sometimes a lengthyproject—to support these devices.

I am very reluctant to purchase anysoftware packaged on a copy-protecteddisk, an "unreadable ROM," or otherwiseimmune to modification to suit our needs.Vendor support of nonstandard hardwareis an admirable goal, but we realize that it

One Man's Dilemma

/ would never break into a computerstore and steal a disk drive, a printer,or a processor card. After all, I'm a de-cent, intelligent, honest person. 1 teachmy children the value of personal in-tegrity, and I pride myself on myhonesty. I never keep overpayments. Ipay my taxes. I even spent over sixmonths convincing a large departmentstore that I owed it money when itcouldn't find any record of the transac-tion. I don't allow my children to makeaudio-tape copies of records for eachother. After ten years in the entertain-ment industry, I know how valuable acopyright is to a performer.

So, how did I become a softwarethief?

It started when I sold my AltairTarbell cassette machine and upgradedto a North Star disk-based system. Iknew when I got the system from afriend that he had piles of software tosupply in the deal. That was the mainreason I worked with him—to get thesoftware. There were about twentydisks full of BASIC games, businessprograms, and a word processor. Aneat little assembler and disassemblerwere included, although my primaryinterests were word processing andBASIC. I rationalized it this way: Iwould never do any commercial workusing any of the programs. I was justlearning—sort of "test driving. " If I diddecide to do any serious programming,I would purchase what I needed tokeep everything legal. I was, after all,an honest man. It worked too well andfor too long.

It wasn't very long before I hadforgotten my commitment; moreover,I wasn't doing any serious work on mycomputer. I did buy an updated ver-sion of North Star BASIC from the fac-tory, which sort of made me legiti-mate. Things were stable for about ayear, with no exchanging or sharing.

Then, I had a letter published in amagazine where I casually mentioned Iwould be interested in exchanging pro-grams. Before I knew it, I had a grow-ing file of others interested in "sharing"what they had. This list eventuallyfocused on an individual in Michiganwho seemed very generous and quitesincere in helping me not only get soft-ware, but in getting it up and running.Over a three-month period this rela-

tionship blossomed into a friendship. Iwas very grateful to this person. I wasdoing most of the receiving and onlyminimal giving, but he didn't seem tomind. There are people who get plea-sure out of helping others.

I was about to submit a softwarereview to a magazine when I was con-fronted with the stark truth: I was athief. I don't know if the fear of beingfound out is what motivated me totake a long, serious look at my past ac-tions. But whatever it was, I was facedwith three problems:

• I had received stolen goods.

• I required these stolen goods everytime I turned on my computer. Thismeant that if I decided to change myposition, I would have to purchase alicense and become a legitimate user ofseveral hundred dollars' worth of pro-grams.

• The explanation I would have to giveto my Michigan buddy. How could Itake his generosity and tell him that,for me, it had become criminal?

I prepared a letter, and, as fatewould have it, he called me while itwas in the mail. I had to tell him what Ihad spent so much time carefullywording. I felt trapped. Finally, Ibegan to unfold how I felt about ex-changing software. I explained thatmine was a unilateral decision andwasn't meant to push him into asimilar repentant attitude. It waswrong for me but not necessarilyeverybody. The words came out, andhe seemed to take it very well andunderstand my position. It was severalmonths before I heard from him again.When I did, he wasn't very friendly. Itwas an impossible situation.

This is the number one problem instealing software: You cannot do italone. Someone knows you will com-promise your values if the price isright. Maybe even worse, you knowyou are helping other people com-promise their values.

During this particularly difficulttime for me, I remembered somethingmy dad had told me when I was a boy.We had just left a friend's ranch afterhearing how he had been paid for twocases of eggs he never delivered. Mydad said, "If a man will cheatsomebody else, he will cheat you."

Text box continued on page 24

22 September 1981 © BYTE Publications Inc

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BYTE September 1981 23

Letter*

cannot be depended on in all situations.The most reliable and useful software thatI have purchased runs under a standardoperating system and is easily modifiableby means of a configuration program or acopy of the source code.

More than once, I have decided not topurchase a desirable software productwhen I became aware that it did not sup-port our system configuration and waspackaged in a copy-protected form. Sure-ly the revenue lost to vendors in this man-ner is as significant as that lost to"pirates."

Our firm plans to enter the small-com-puter-software market through direct andretail sales. BYTE readers should be as-sured that our programs will be fully ac-cessible, modifiable, and packaged withsource code whenever feasible.

Yes—we'll be vulnerable to piracy. ButI believe that the solution to the software-piracy problem is increased vendor sup-port (rendering pirated copies less valu-able) and vigilant enforcement of protec-tive laws, not making software productsless accessible to the user.

Michael C BerchManaging PartnerSouthside Systems2424 Haste StSuite A-40Berkeley CA 94704

I would like to comment on the May1981 BYTE editorial and the two articleson the subject of software piracy. Thereare two sides of every fence. BYTE tookthe side of the software provider; let metake the side of the user.

I purchased an Apple II, disk drives,video monitor, printer, modem, etc, plusabout $1000 worth of software for busi-ness use. This is not my hobby, and I haveno intention of becoming any more of anexpert with computers than I must toachieve my purpose.

From my standpoint, the price of all ofthis stuff is so low that there is absolutelyno point in messing around either with pi-rates or in doing it myself. Even the book-keeping and inventory-control programs,at $600 to $1000 or more, pay for them-selves in a few months. If the minicomput-er manufacturers could ever get their acttogether, the business-software marketwould dwarf their present endeavors. (Ithink that the Japanese will do the job forthem, and Apple will wind up back in theold garage along with the others.)

Text box continued:

There is no sacred bond above whichall transactions are honest and belowwhich honesty is negotiated.

I sent away for the software I re-quired to keep writing. As luck wouldhave it, I had been legitimately giventwo key pieces of software, that weremine to keep, in return for providingreviews to magazines. So as it turnedout, 1 had won and I had lost. Cleaningup my act didn't cost me as much as Ithought it would; however, I lost afriend. I consider that loss the highestprice to pay for my transgression.

I'm sure there are those who will becritical and demand I pay for the soft-ware I used for the two years. All I cansay is that I've given it careful thoughtand I feel comfortable with my currentsituation.

Foolproof, protected software is fic-tion and will never be reality because ithas nothing to do with technology. Ithas to do with the human condition.There always will be people who willcompromise integrity for materialgain. And there will be those, likemyself, who will slip past honesty andinto what they often call a "gray area"before they get their heads out of thesand and take responsibility for theiractions. And, thank God, there are ahandful whose integrity will notwaiver. As long as this human condi-tion exists, there will be no perfectsystem for software protection.

There are, perhaps, only tworeasons for maintaining personal in-tegrity. One is the fear of beingdiscovered and exposed—or worse,punished. An idea I read a year or soago suggested that a bounty on piratesmay be the most workable tool to en-force this first reason. I don't like thisidea: there are too many holes in it.But it does seem the most effective wayto put the fear of being caught intopirating.

On the other hand, there is themoral fiber within each of us thatmerely needs to be awakened to be-come strong and effective. Careful ex-amination of your situation with acritical eye on what you know to beright and wrong will certainly exposeany deficiencies. It then becomes amatter of pricing your integrity andremembering that you can't steal soft-ware by yourself. Yes, the process ofevaluating the circumstances is simple.The difficulty of implementation willlikely be directly proportional to howdeeply involved you are in stealing.

Drop me a postcard—anonymously,if you prefer—and let me know yourfeelings.

Eugene Dorman

c/o BYTE Publications Inc

POB 372

Hancock NH 03449

I have two Apple programs that pro-vide access to the Dow Jones data base forthe purpose of obtaining securities quotes,keeping track of portfolios, and the like.One program is written in BASIC, is user-accessible and, with some user modifica-tions, works like a charm. The other pro-gram is "locked." It doesn't work.

Apple has a disclaimer in its programmanuals absolving them of all respon-sibility. So far, Apple hasn't abandonedme, but it's taking its own sweet timeabout coming up with a fix. When and if afix comes through, no field modificationby the user will be possible. I have a pret-ty good idea what the problem is and if Icould gain access to the program, I couldprobably fix it myself in a short time. Thisway it will take weeks or months, if it getsfixed at all. I think the denouement is thata determined and knowledgeable piratewill succeed no matter what, while the

honest and legitimate user, like me, takesit on the chin.

Adolph L Friedman

POB 2856

Santa Fe NM 87501

I disagree with Chris Morgan's editorialon software piracy. It seems that the soft-ware expert has a stranglehold on the per-sonal computer. His hand is clutchedaround my wallet and he is squeezing forall it is worth. I don't like that. In thecapitalistic system, competition brings theprice in line. Software is a monopoly, andMr Morgan's concern is like government-secured loans to Chrysler.

Why not let the software people pro-vide more flexibility to the user7 If thesoftware is easier to obtain and morereasonably priced, a larger number ofpeople would own personal computers.

24 September 1981 © BYTE Publications Inc

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That in itself would increase the marketfor software. The broader the base of peo-ple using computers, the greater the varia-tions and the need for software.

What Mr Morgan proposes is like Ex-xon buying up the "good gas-mileage car-buretors" before they get to market. Itsounds to me that Mr Morgan is trying toprotect the pirates.

Brigg Leurs436 N 1050 EKaysville UT 84037

It seems to me that the solution to soft-ware piracy has been evident and used fora considerable time by BYTE's parentcompany, McGraw-Hill. Hundreds ofman-hours can be used in the writing anddebugging of a program, and this can betranslated into cost and selling price, thesame as any other commodity.

The Osborne Accounting System, forexample, has a finite value. The disks foreach program are available at a very lowprice, even as low as $8, from one ofBYTE's advertisers. However, the com-prehensive and beautifully publishedmanuals that include the source code canbe purchased for $20. You could notphotostat one of these manuals for lessthan this price. Therefore, you buy it.

It would be interesting to know howmany manuals the McGraw-Hill BookCompany has sold and what the incomehas been, per program. I'm sure thisshows one solution: give the disk awayand sell the manuals, like the old stunt ofgiving the razor away, but selling theblades. All of the methods for "locking in"programs and "locking out" softwarepirates are rather foolish. Everyoneknows that you can access every byte onevery track, change the ID and password,

disassemble, and transfer from one systemto another.

A A Schwartz

6454 EI Camino Del Teatro

La Jolla CA 92037

The antipiracy devices mentioned inChris Morgan's editorial are quite in-genious, but like all human inventions,they are fallible. I wonder if BYTE readerswould like to reconsider the whole ques-tion of "software protectionism" at a moreelementary level.

I can identify at least three basic "in-stincts" at work which must be accommo-dated:

• the natural inquisitiveness of the humanmind

• the insatiable attraction of acquiringthings for oneself

• and the irresistible challenge of anotherhuman mind

Inasmuch as knowledge and informa-tion are the essential contents of all soft-ware, to keep them "locked away" is old-fashioned logic. Widely disseminatedknowledge will bring forth more knowl-edge. In an age when knowledge becomesrapidly outdated, hanging on to some lit-tle invention is unrealistic. Like all at-tempts at prohibition, the setting up ofbarriers is probably the most potentstimulus to overcome them. Such at-tempts have only resulted in the escalationof costs to the consumer, the productionof weird and delicate formats that aremuch more prone to crashes, and thegreat step backward of adding un-necessary keys and ROMs (read-onlymemories) that defeat the advantage ofcomputerization.

Is it too late to take a 180° turn and stopthis "cold war" from escalating? Would itbe possible to take the alternate view7Here are some suggestions:

• The ultimate way of getting rid of piracyis to make the purchase of genuine soft-ware so cheap that it becomes uneconom-ical to copy. Who bothers photocopyingpaperback books? The volume of saleswill more than compensate for the lower-ing of the profit margin and protectioncosts.

• Software houses should encourage usersto become subscribing members. Thiswould provide capital for software devel-opment as well as some degree of customi-zation of the software to be developed.New programs could be offered to sub-scribers on a priority discount basis.

• Users clubs should be encouraged toadopt a code of ethics; in ieturn theywould be allowed to participate in ascheme of evaluation and bulk ordering ofnew products. There is no pressure greaterthan peer pressure.

• A good user and upgrading serviceshould be arranged so that a firm bond iscreated between the user and the softwareproducer. Newsletters with user com-ments is one way to achieve this.

I am glad to say that at least one soft-ware company, Personal Software, hasbegun to adopt this new attitude for itsData Management System and DesktopPlan. I salute them. I sincerely hope thatBYTE and its readers will take the initia-tive of spearheading this more rational ap-proach before you have to say "opensesame" to your computer.

Dr A Hua

Department of Medicine

Queen Mary Hospital

University of Hong Kong

Hong Kong Letters continued on page 30

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Letters,

The Wind BlowestWhere It Llsteth

Something is a bit strange about BYTE'sMay 1981 cover. The sail is full and set fora run (which means wind astern), theburgee points to port (which means windoff the starboard), and the spray from thebow wave points to starboard (whichmeans wind to port). I've seen things likethis on a lake just leeward of an island,but only for a moment. It's pretty unlikelyon the open sea. And, worst of all, the sailhas a big hole in itl

BYTE's cover has inspired a newdisparaging remark about a landlubber:he doesn't know his sail from a floppydisk.

John A BallOak Hill RdHarvard MA 01451

The May cover is a faithful representa-tion of a situation that occurred duringthe BYTE staff's last outing. By the way,we know about floppy disks, but what's a"sail"? . . . CPF

Programming As an Essay

As a programmer whose background isin literature, I am naturally sympatheticto the analogy between programming andnatural languages that John Handel drawsin his article 'The New Literacy: Pro-gramming Languages as Languages." (Seethe March 1981 BYTE, page 300.) That aprogramming language is indeed called alanguage, that programming borrowsmuch of its lingual terminology fromnatural languages (eg: word, paragraph,syntax), offers at least a hint of theparallel that Mr Handel persuasivelydevelops.

At one point, however, he makes ananalogy between a program and a bookthat I find a bit contrived. His argumentwould be better served with an analogybetween a program and a formal essay.Having written both, I find the thoughtprocesses involved in both remarkablysimilar.

Essentially, a formal essay consists of athesis, arguments to support that thesis,and a conclusion. Its usual purpose is tointerpret, persuade, or inform: to solvesome critical or rhetorical problem. Beforewriting can begin, an essayist must be ableto express clearly to him- or herself thethesis and conclusion in order to define

30 September 1981 © BYTE Publications Inc

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the problem, its scope, and to provide aframework for its solution. Similarly, aprogrammer must have a definition of hisor her problem, and he or she must beable to frame a solution before coding canbegin. Both the essayist and the program-mer must know where they want to gobefore they can begin the detailed work toget there.

Next, the essayist must gather his or hermajor arguments and break the thesis intocomponents, just as a programmer willbreak the problem into manageable parts.A writer will then arrange the argumentsso that they flow smoothly through the

essay. A programmer will begin arrangingthe parts of the problem so that theyoperate in an orderly fashion.

Finally, the detail work can begin. Awriter will supply minor arguments andexamples to "flesh out" his or her work. Aprogrammer at this point concentrates oncode. Both will polish their work, en-suring that grammar, diction, and syntaxare correct.

An essay may not have to communicate"in a precise fashion" and an essayist mustrely on a reader to "test" the thesis (not asstrict a standard as a programmer's com-puter), but an essay must communicate in

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32 September 1981 © BYTE Publications Inc

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a reasoned and orderly fashion. Bothwriter and programmer must be logicalwithin a verbal framework.

I agree with Mr Handel's conclusionthat a programmer with verbal sensibilitywill tend to write readable programs thatwork. Perhaps then, programming in-stallations, especially commercial shopswhere the work is not technical or mathe-matical, may do well to employ languageand linguistic students. Perhaps too, asource of programming talent may befound in writers and students of philo-sophy and history who already have acommand of language and proceduralskill and who could learn the particularsof programming quickly and easily.

Michael J Nichols1725 York AveNew York NY 10028

Vikings Defense

It may be that BYTE's attention some-how has been focused on the aspects ofviolence in the history of the Vikings. Thecover on the May 1981 BYTE and the texton page 4 does, however, indicate thatBYTE ought to read up on the Vikings aswell as on their contemporary history.

BYTE has done the Vikings a gross in-justice by merely stating that they were"notorious pirates." Let me say in theirdefense that they were also clever sailors,innovative navigators, explorers, andtradesmen, who traveled routes that to-day seem impossible considering theequipment they had at hand. They weretough, maybe, and violent—living intimes of different general ethics and valuesthan you may wish for yourself today.But, to call them pirates, with an indica-tion of lawlessness, is simply an (unfair)application of current values to a very dif-ferent time and place.

The Vikings also were clever ship-builders, building perhaps the mostbeautiful boats that have ever been made.You may see some of these here in Osloand judge for yourself.

F.inar SkjortenRytterfaret 211347 Hosle, Norway

We apologize, Mr Skjorten, for oursomewhat simplistic representation of theVikings. . . . CMi

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Book Reviews

Principles of

Artificial

Intelligence

Nils J NilssonTioga Publishing, 1980476 pages, hardcoverS27.50

Reviewed bySteven K Roberts andJames Paul Jenal5885 Dublin RdDublin OH 43017

Artificial intelligence (AI),for over two decades the ar-cane province of academicvisionaries, is at last spillingover into the worlds of engi-neering and practical systemdesign. A fascination with theprogramming language LISPis sweeping the industry, ro-botics and machine vision(though still primitive) aresomething other than fan-tasy, and the cost of com-puter hardware on a scalenecessary for AI work hasdropped to the point where iteven touches the personalcomputer spectrum.

It is becoming worthwhileto learn something about thesubject for reasons beyondintellectual curiosity.

A new book by Nils JNilsson offers a substantivelook at a body of techniquesupon which much of thework in the artificial intelli-gence field is based. Presentlythe director of the ArtificialIntelligence Center of Stan-ford Research Institute,Nilsson has for years been in-volved in problem-solving,theorem-proving, and plan-ning systems, and hasauthored publications alongthese lines that date back tothe early 1960s.

Principles of Artificial In-telligence is intended as a textfor a college senior or first-year graduate student, andcan thus be considered to bethe reader's first serious ex-posure to the field. But a

question arises as to whetheror not the ensuing (fairly rig-orous) discussion of predicatecalculus is the way to pro-ceed. Though the text waswritten as an introductionand does, in fact, concern it-self far more with underlyingtechniques than with applica-tions areas, it focuses fairlystrongly upon formalismswith which the reader new tothe field might be a little un-comfortable.

Predicate calculus is cer-tainly not new to serious stu-dents of computer science—itis required material in almostany undergraduate com-puter-science curriculum,though exposure is typicallylimited to formal proving ex-ercises. Nevertheless,predicate calculus does pro-vide a refined set ofmanipulative tools that areuseful for the implementationof knowledge-based pro-duction systems, and it has adistinct advantage over someof the more intuitive para-digms, such as relationaldatabases and semantic net-works, in that it has maturedfrom many years of disci-plined development in otherapplication areas. Thoughimposing in appearance, it isa reliable basis for system de-sign and, thanks to its univer-sal acceptance, for communi-cation of ideas with otherworkers in the field.

However, one of the idealsof artificial intelligence workis the comfortable bridging ofthe vast conceptual gap be-tween man and machine. Al-though this inevitably re-quires the application of for-mal tools, it should even-tually lead to increased"naturalness" of problem ex-pression. In a purely rigoroussense, any Turing machineimplementation is as good asanother (they provide thesame computing power), butthe differences to those who

must use them are significant.As anyone who has ever at-tempted to express abstract,symbolic constructs withinthe syntactical and semanticrestrictions of FORTRANknows only too well, theissue of naturalness is inex-orably tied to the representa-tion problem.

Early on, Nilsson statesthat "selecting a good repre-sentation is one of the impor-tant arts involved in applyingAI techniques to practicalproblems." This is indeedtrue, not only in this field butin all aspects of computerproblem solving. Knowledgerepresentation, whether via abody of production rules(if...then constructs), frames(relatively passive data en-tities appropriately intercon-nected and applied to a set ofinference procedures), or anyother means, is a central andhotly contested issue that af-fects not only the usefulnessof a system's design but itsnaturalness. While differentapproaches may not neces-sarily provide greater power,they might free the mind toachieve greater insights—andinsight is at the heart of allproblem solving.

Nilsson makes a good casefor the use of predicate cal-culus as the set of "cranks"with which any type of sys-tem can be implemented.Whether or not this approachconstitutes an optimal entryinto the artificial intelligencefield is partly a function ofthe reader. From a classicalengineering standpoint, theassimilation of formalmethods before exposure tothe more philosophicalaspects is absolutely neces-sary, and for those who arecomfortable with this ap-proach, the book comeshighly recommended: theproblems are interesting, yetnot so esoteric that you losesight of their purpose—name-

ly, the chance to apply theprinciples that Nilsson has sopainstakingly laid out. Thosewho lack the text's presup-posed ease with formalmethods (and there is muchof interest in the field thatdoes not require it) mightprefer a book targeted to anoverview of AI's various sub-specialties (such as Patrick HWinston's classic, ArtificialIntelligence, Philip CJackson's Introduction toArtificial Intelligence, orPamela McCorduck's Mach-ines Who Think).

Principles of Artificial In-telligence, like its pre-decessor, Problem-SolvingMethods in Artificial Intelli-gence (Nilsson, McGraw-Hill, 1971), can be consideredan authoritative text on manyof the underlying ideas thatserve as the basis for the bulkof current artificial intelli-gence research. After Nilssondevelops the primary theme,he provides a number of pro-vocative comments about thefield, and closes with a com-prehensive and up-to-datebibliography of publishedworks. Though hardly casualreading, the book offers solidunderpinnings for method-ologies which might other-wise appear disquietinglymagical. ■

34 September 1981 © BYTE Publications Inc

Circle 312 on inquiry card. —*■

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NAME

I STREET

| CITY

STATE

LZ,P .

PHONE

A LOOKAT NCC 01

by Steven K Roberts, 5885 Dublin Rd, Dublin OH 43017

This year's National Computer Conference, held lastMay 4 through 7 at McCormick Place in Chicago,was so large that nobody could effectively see all ofthe show in the four days allotted to it. In fact, withabout 73,000 people attending, it was often difficult tosee the displays at all. The task was also complicatedby the juxtaposition of booths for every type of com-puter, from microcomputer to mainframe, andtheir associated suppliesand peripherals. Still,what I did see was ex-citing; shown here aresome of the attractions.

36 September 1981 © BYTE Publications Inc

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I Any attempt to capture the entire NCC in asingle photograph is doomed to failure.

I The BMC IF-800 microcomputer. This newentry from Japan is impressive, although itsprice might be too high for the casual user.

3 The LEX-21 is a portable terminal with a full-size keyboard, a 40-column printer, a buffer ofup to 8 K bytes of memory, and a built-indirect-connect 300-baud modem.

4 The Apple booth was constantly well at-tended because of the many applications beingdemonstrated.

5 The Corvus Omninet, a local networksystem that can interconnect up to 64microcomputers via a simple twisted-pair wireconnection. Each microcomputer connects tothe twisted-pair bus through an interface calleda "transporter." Interfaces now exist for Apple,LSI-11, and Onyx computers.

6 BASF's slimline 5.25-inch floppy-disk drives.Three of these units will fit in the space of twodrives of conventional design.

7 The TRS-80 Color Computer was displayedprominently at the Radio Shack booth. Withits Extended Color BASIC, the unit can deliverimpressive color graphics.

8 and 10 The Xerox Star. A view of the unit'svideo display, photo 8, shows why the Starwas one of the most popular exhibits at theshow—it delivers on its promise of "What yousee on-screen is what you get." Photo 10 showsthe Star itself, an intelligent office terminal thatcan be connected to Xerox's Ethernet.

9 The Sony Typecorder, a self-contained,battery-powered "portable office" about thesize of an issue of BYTE. The unit stores bothvoice and text (up to 120 pages) on a microcas-sette and can dump text to a printer or transmitit over telephone lines.

II Tandon displayed an 8-inch floppy-diskdrive that is exactly half the width of conven-tional units.

12 A high-resolution display usingCromemco's Super Dazzler board along withits SDI color-graphics interface. The resultingvideo image can be made from a palette of 2048colors.

September 1981 © BYTE Publications Inc 37

Ciarcia's Circuit Cellar

Build an Unlimited-VocabularySpeech Synthesizer

Steve Ciarcia

POB 582

Glastonbury CT 06033

The alarm clock that jolts you outof sweet dreams with a monotonebuzz is a thing of the past. State-of-the-art technology is the clock thatprods you out of slumber with a voicethat speaks your own language: "Thetime is 6 o'clock."

The artificial voice is becoming anincreasingly important and potential-ly indispensable part of the interfacebetween man and machine. Electronicspeech synthesis is a young but rapid-ly evolving technology. It won't belong before that speaking alarm clockwill also announce your entire day'sappointment schedule. It will be noless unusual for the computer in yourcar to recount its mechanical ills asyou drive to work. For now, how-ever, electronic speech synthesis isstill a relatively new concept.

In a previous Circuit Cellar article("Build a Low-Cost Speech-Synthe-sizer Interface," June 1981 BYTE,page 46), I described the design of aninexpensive, limited-vocabulary, com-puter-controlled electronic speechsynthesizer called the Micromouth.This speech processor, based on theNational Semiconductor Digitalkerchip set, was an attempt to introduce

Votrax is a trademark of Federal Screw Works,Inc.

Digitalker is a trademark of National Semicon-ductor Corporation.

Copyright © 1981 by Steven A Ciarcia.All rights reserved.

personal computer users to artificialspeech. Considering the response itreceived, I believe many of you arenow listening to everything yourcomputer has to say.

This month I wish to return to thetopic of computer-controlled elec-tronic voice synthesis and introduceyou to the Votrax SC-01 speech syn-thesizer chip.

Instead of waveform digitization orlinear-predictive coding, the SC-01uses phoneme synthesis, whichallows the SC-01 to speak an un-limited vocabulary simply by sequen-tially pronouncing the individualphonemes (basic sound units) thatmake up words in the English lan-guage.

Many other articles have been writ-ten that describe in detail the theoryof phoneme synthesis and the work-ings of the Votrax SC-01 integratedcircuit. A few appropriate referencesare given at the end of this article. In-stead of discussing many theoreticalconcepts at length in my limited spacehere, I prefer to concentrate on thedesign of a practical, computer-con-trolled, phonetic speech synthesizer.

This month's construction project,shown in photo 1, is called the SweetTalker speech synthesizer. It uses theSC-01 integrated circuit to allow syn-

Special thanks to Ray Long of Custom Photoand to Greg Peterson and Phil Walton of TechCircuits for their expert printed-circuit designand production talents.

thesis of an almost unlimited vocabu-lary (limited only by the size andcomplexity of the controlling pro-gram running on the computer). TheSweet Talker circuit contains I/O (in-put/output) signal buffering, a clockoscillator, an audio filter, and anamplifier. The circuit board providesprotection from static electricity forthe SC-01 in addition to being a con-venient package. (Protection for theSC-01 is important, because it is bothexpensive—$70—and delicate. It'smade using complementary metal-oxide semiconductor technology.)The standard Sweet Talker synthe-sizer can be connected to any micro-computer through a parallel port,while a special version of the unit canbe plugged into the I/O bus of theApple II computer.

Speech-Synthesis Review

Three major techniques are pre-sently used to synthesize the humanvoice: formant synthesis, linear-pre-dictive coding (LPC), and waveformdigitization. They differ in the num-ber of bits of data required to con-struct a word.

Formant synthesis is essentially anelectronic modeling of the naturalresonances of the human vocal tract.Bands of resonant frequencies in thevocal spectrum, called formants, aregenerated by excitation sources andthen passed through variable filters.

One variation of the formant tech-nique is called phoneme synthesis, in

38 September 1981 © BYTE Publications Inc

Photo 1: The assembled Sweet Talker phonetic-speech-synthesizer circuit board.The Votrax SC-01 phoneme-synthesizer integrated circuit supports a vocabularylimited only by the size and complexity of the computer program that controlsthe Sweet Talker. Any English word may be constructed from phonemes, thebasic building blocks of speech. The circuit board shown is a prototype of theparallel-port version of the Sweet Talker; the Apple II plug-compatible version isnot shown.

Votrax® CMOS Phoneme Speech Synthesize

Photo 2: The Votrax SC-01 is a 22-pin CMOS integrated circuit which functionsas an electronic model of the human voice.

Photo 3: Before the development of the SC-01, Votrax used many medium-scale-integrated circuits and discrete components to perform the same functions. Allthese components were mounted in modules such as the VSL-type shown. Whenthis particular synthesizer card was purchased three years ago, the price was$600. Compare this both in size and price to the $70 SC-01 (sitting on top).

which the spectral parameters are de-rived from basic sound units thatmake up words. A phoneme-genera-tor circuit is used to reproduce thesesounds. In such a circuit, each pho-neme is given a numeric code, and thesynthesizer circuit (discrete or inte-grated) utters phoneme sounds corre-sponding to codes it receives when itis activated. Words and sentences areassembled by simply stringing thephoneme codes together. The elec-tronic voice so generated is intelligi-ble, but has a slight mechanical quali-ty. Continuous speech using pho-neme synthesis can typically be gen-erated with a data rate of less than100 bps (bits per second).

Linear-predictive coding is similarto formant synthesis in that bothtechniques are based in the frequencydomain and use similar hardware tomodel the vocal tract. The quality ofspeech is often better than formant orphoneme synthesis, but a higher datarate (1200 to 2400 bps) is needed forcontinuous speech.

Waveform digitization is the thirdmethod of speech synthesis, in whichthe amplitude characteristics of avocal waveform are stored and repro-duced. The quality of speech is betterthan the other two methods, but thedata rate for continuous speech isvery high, and storing sufficientamounts of data conveniently can bea problem. Various schemes of com-pressing the data have been devised;one of the more successful is used inthe National Semiconductor Digi-talker system, which I described inmy June Circuit Cellar article.

Votrax SC-01

The 22-pin Votrax SC-01 inte-grated circuit, shown in photo 2 andin the diagrams in figure 1, contains adigital code translator, or phonemecontroller, and an electronic analogof the human vocal tract. The pho-neme controller translates a 6-bitphoneme code and a 2-bit pitch codeinto a matrix of spectral parameterswhich in turn adjusts the vocal-tractanalog to synthesize the phonemes.

In the first part of the vocal-tractsection, there are a pair of variable-frequency oscillators for simulating

September 1981 © BYTE Publications Inc 39

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]mcrc

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8

15

]mcx

psD

9

14

]po

P4[j

10

13

]P1

P3[

11

12

]P2

NC =

NO

CONNECT

ON

TPX

= NO

CONNEC

TION

lib)

LATCH

PHONEME

CODE

ACKNOWLEDGE/

REQUEST

NEW

PHONEME

DATA

J /-rsC

AUDIO OUTPUT

tic)

II 12

TP1 TP2 TP3 NC NC

Figure 1: Technical characteristics of the Votrax SC-01 Speech Synthesizer Chip. Shown are the pinout designations (la), thescheme of data flow through the circuit (lb), and a block diagram of the internal structure (1c). This figure is reproduced courtesy ofthe Votrax Division of Federal Screw Works, Inc.

40 September 1981 © BYTE Publications Inc

S DATA BUS J

2-BITLATCH

SELECBUSY/IP

TERRUPT-*-

MCRCMCX

VOTRAXSC-01

T

CLOCK

f0= 1.25/RCRMIN = 6.5KCMAX = 300pFSET FOR 720kHz

Figure 2: A diagram of the general connection scheme of the 5C-01.

vocal-cord-produced periodic soundsand a pseudorandom (pink-noise)signal generator that simulates thesound of rushing air. The outputsignals from these sources are shapedby a bank of four analog band-passfilters that simulate the vocal-tractcavities. The filter outputs, in turn,are directed through a preamplifier toan external amplifier and speaker.

The SC-01 phoneme synthesizer isa CMOS (complementary metal-oxidesemiconductor) integrated circuitwhich should be operated within therange of 7 to 14 V (V„). The pho-neme-input lines (P0 through P5) are5 V level-compatible and self-latch-ing. (Here "5 V level-compatible"means matching LSTTL [low-powerSchottky transistor-transistor logic]

Photo 4: The Sweet Talker phonetic-speech-synthesizer board can be driventhrough any parallel output port. One port which can be used is a Centronics-compatible parallel printer port. When using this connection, phonemes forwords to be spoken are transmitted using LPRINT statements in BASIC. Picturedabove is the Sweet Talker board combined with its power supply and connectedto a TRS-80 Model III computer and a speaker.

levels with an external pull-upresistor.) The two pitch-control lines,on the other hand, must have externallatches and must be switched at thesame input voltage as the SC-01'spower supply. Handshaking with ex-ternal control circuitry is accom-plished through two control lines:strobe (STB) and acknowledge/request(A/R). The STB line can be eitherCMOS or 5 V level, while the A/Rline is CMOS level only.

The output pitch of the phonemesis controlled by the frequency of theclock signal, which can be appliedfrom an external source or set inter-nally with a resistor and capacitorcombination. The clock frequency isnominally 720 kHz, but subtle varia-tions of pitch are induced through"automatic inflection" to prevent thesynthesized voice from sounding toomonotonous or "robot-like." Two in-dependent pitch-control lines, II and12, are available for gross variationsin pitch so that the chip can speakwith more than one voice. Referred toas "manual inflection" controls, IIand 12 operate in addition to the auto-matic-inflection system already pre-sent. I have found that the 6-bit pho-neme code alone is sufficient, and thetwo pitch-control lines can be ig-nored. A diagram of the general con-nection scheme is shown in figure 2.

Listed in table 1 on page 42 are the64 phonemes defined for the Englishlanguage (two produce silent periodsof different lengths; one causes syn-thesis to stop). A phoneme sound isgenerated when a 6-bit phoneme codeis placed on the control-register inputlines (P0 through P5) and latched bypulsing the strobe (STB) input. Eachphoneme is internally timed and has aduration of 47 to 250 ms (millisec-onds); some phonemes last longerthan others, and variations in theclock frequency affect the phonemedurations. The A/R line goes from alogic 1 to a logic 0 when a phoneme issounding.

There are two general methods forusing the SC-01. One method, shownin figure 3a on page 43, configures thechip in an independently acting, self-timed circuit which asynchronouslyextracts phoneme codes from a

September 1981 © BYTE Publications lnc 41

Hexadecimal

Phoneme

ASCII

Duration

Example

Phoneme

Symbol

Character

(ms)

Word

Code

00

EH3

@

59

jacket

01

EH2

A

71

enlist

02

EH1

B

121

heavy

03

PAO

C

47

no sound

04

DT

D

47

buffer

05

A2

E

71

make

06

A1

F

103

pa/I

07

ZH

G

90

pleasure

08

AH2

H

71

honest

09

13

I

55

inhib/t

0A

12

J

80

inhibit

OB

11

K

121

inh/blt

OC

M

L

103

mat

OD

N

M

80

sun

OE

B

N

71

bag

OF

V

0

71

van

10

CH

P

71

cnip

11

SH

Q

121

snop

12

Z

R

71

zoo

13

AW1

S

146

lawful

14

NG

T

121

thing

15

AH1

U

146

father

16

001

V

103

looking

17

00

w

185

book

18

L

X

103

/and

19

K

Y

80

tric/r

1A

J

z

47

judge

1B

H

[

71

hello

1C

G

\

71

get

1D

F

]

103

fast

1E

D

1

55

paid

1F

S

—

90

pass

20

A

(space)

185

tame

21

AY

!

65

jade

22

Y1

"

80

yard

23

UH3

§

47

miss/on

24

AH

$

250

mop

25

P

%

103

past

26

0

&

185

cold

27

I

1

185

p/n

28

U

(

185

move

29

Y

)

103

any

2A

T

*

71

fap

2B

R

+

90

red

2C

E

,

185

meet

2D

W

—

80

win

2E

AE

185

dad

2F

AE1

/

103

after

30

AW2

0

90

salty

31

UH2

1

71

about

32

UH1

2

103

uncle

33

UH

3

185

cup

34

02

4

80

bold

35

01

5

121

aboard

36

IU

6

59

you

37

U1

7

90

June

38

THV

8

80

the

39

TH

9

71

fhin

3A

ER

146

bird

3B

EH

J

185

ready

3C

E1

<

121

be

3D

AW

=

250

call

3E

PA1

>

185

no sound

3F

STOP

?

47

no sound

Note: T must precede

CH to produce

"CH" sound.

D must precede

J to produce

'J" sound.

Table 1: The sixty-four

phonemes defined for the English language

Two of these

produce silence; one causes synthesis

to cease.

dedicated memory buffer. Typically a32- or 64-character FIFO (first-in,first-out) buffer is attached to thecomputer bus and loaded with thephoneme codes under program con-trol. Once loaded, the codes areshifted out one at a time as the STBand A/R lines changestates. This self-clocking techniquecan also be used with an EPROM(erasable programmable read-onlymemory) and a counter when theSC-01 is to speak a canned messagewithout computer control.

While use of a FIFO buffer reducesthe main processor's waiting timewhen exercising relatively slow (typi-cally 70 bps) peripheral devices suchas the SC-01, buffers are expensive.Interface-hardware costs can bemeasurably reduced by a secondscheme: using the computer system(running an appropriate program) totime the transmission of phonemecodes to the SC-01, as outlined infigure 3b. This method sends codes tothe synthesizer chip through a latchedparallel output port and monitors thesynthesizer's activities (via the A/Rline) through an input port or inter-rupt line.

The latter is the technique I choseto use in my design. Interestinglyenough, eliminating the extra hard-ware doesn't really complicate com-puter/synthesizer interaction nordoes it require a sophisticated ma-chine-language driver program likethose ordinarily associated with soft-ware-controlled peripheral devices.The program code to control the syn-thesizer can be as simple as anLPRINT statement in BASIC. Moreon this later.

Sweet Talker

The schematic diagram of theSweet Talker speech-synthesizer cir-cuit board is shown in figure 4 onpage 44. The phoneme-code bits aresent in parallel to the SC-01 (IC3) andbuffered through ICl (a 74LS244three-state octal buffer). Pull-upresistors assure that a logic-1 input tothe SC-01 will be at least 4 V as re-quired. Unless the board is being usedwith external address circuitry, theEnable input line (on connector Jl,

42 September 1981 © BYTE Publications Inc

(3a)

WRITE

v

SC-01

P0-P511, 12

STBA/R

IN

SHIFT INFl FO

SHIFT OUT

OUT

<?

DATA BUS )

")

II

l

(3b)

L

DATA BUS

^S

D

8-BIT

OUTPUT

LATCH

}

INPUTBUFFER

STB

P0-P5II, 12

SC-01

A/R

OR INTERRUPTINPUT

Figure 3: Two methods of interfacing the SC-01 to a microcomputer data bus. Figure 3ashows an independently acting, self-timed circuit with a FIFO (first-in, first-out) buffer.Figure 3b shows a circuit that allows the computer to time the transmission of data tothe SC-01.

Photo 5: Many computers have serial, rather than parallel, I/O ports. With a lit-tle extra hardware, it is possible to add a serial interface to the Sweet Talker.

pin 12) should be grounded, therebycontinuously enabling the buffer.

The two manual-inflection inputs(II and 12) are also buffered throughICl. The SC-01 cannot store thesesignals, and storage must be providedexternally. A 74LS74 type-D flip-flop(IC2) is configured as a 2-bit latch. Itis clocked synchronously with theSC-01's strobe input. Unlike the pho-neme inputs, however, the inflectionlines are not 5 V compatible. Twosections of a 7416 open-collectorinverter (IC4) are used with pull-upresistors to level-shift these data in-puts to CMOS levels. Since the auto-matic inflection is generally adequate,the manual-inflection inputs (Jl, pins16 and 20) can be left open orgrounded when not in use.

The SC-01 can use either its inter-nal clock or an external clock. Exter-nal clock signals are applied throughpin 15 on the SC-01 while pin 16 isgrounded. My design uses the inter-nal clock-signal generator, instead.The clock frequency is determined byan R/C (resistor/capacitor) combina-tion attached to pins 15 and 16. Thefrequency is adjusted through poten-tiometer R8 and nominally set for 720kHz. Slight adjustments to this con-trol will vary the pitch of the speech.The easiest way to set this potentio-meter is by ear. Simply output a se-quence of phonemes to the SC-01 andset R8 for the most pleasant-soundingvoice.

The process of sounding a pho-neme begins when the 6-bit phonemecode is latched into the SC-01's con-trol register. Latching occurs whenthe rising edge of a positive-goingstrobe pulse is received on pin 7 of theSC-01, the STB input line. The syn-thesizer will continue to sound thesame phoneme until another pho-neme code or a stop code is loaded.

The Sweet Talker circuit board canbe set up (through jumper connec-tions) to accept either a normally highor a normally low strobe signal fromthe external computer. Two sectionsof the inverter IC4 are involved inthis flexibility. The normally highstrobe signal connects to the SweetTalker board through pin Y of theedge connector Jl, while the normally

September 1981 © BYTE Publications Inc 43

a.r- o

D

o

>

try

+

O NCON V

O

wo<ogscor 1

0)

E

c\j co *r m'O OOO

— r- < UJ -i o

ocoi_]OtrQ oOixi

---9-9—i~i—A—A—A—A—A—A

& &-

Figure 4: Schematic diagram of the Sweet Talker phonetic speech synthesizer in the parallel-port version.

44 September 1981 © BYTE Publications Inc

low strobe signal connects throughpin 21. The two inputs cannot be usedin exactly the same way, however,because of some timing restrictionsimposed by the SC-01.

The SC-01 senses the positive-going edge of the strobe pulse arriv-ing on its pin 7, but unlike typicalTTL latches (which operate in a fewnanoseconds), the SC-01 requiressome setup time before it can acceptthe strobe signal. This setup timemust meet two requirements:

• The data on the phoneme-inputlines PO through P5 must have beenstable for 450 ns before the rising edgeof the strobe pulse arrives.

• The logic level on the STB input ofthe SC-01 (pin 7) must have been lowduring at least 72 clock periods (ap-proximately 100 microseconds)before it goes high for the strobepulse.

The staggered timing of the pho-neme data and the strobe pulse makesinterfacing the SC-01 directly to amicrocomputer data bus difficultwithout the use of an external datalatch (an output port).

Furthermore, in some cases (de-pending upon the method of connec-tion), when the Sweet Talker board isbeing driven through a parallel out-put port that uses a DAV (data avail-able) strobe signal, you may have toadd a one-shot (monostable multi-vibrator) to the circuit to stretch thesignal out so that the logic level at pin7 of the SC-01 stays low long enough.The DAV strobe signal of a typicalmicroprocessor is less than a micro-second in length.

Approximately 500 nanosecondsafter the rising edge of the strobepulse, the A/R line (pin 8) of the SC-01goes to a logic 0, indicating that thesynthesizer chip is busy. TransistorQl and IC4 convert the CMOS_out-put of pin 8 to LSTTL levels. The A/Routput can be monitored by the con-trolling computer in either of twoways: directly through an input portor connected to an interrupt line. Ineither case, when the A/R line returnsto the logic-1 level, the SC-01 is readyto receive another phoneme code.

The remaining components on theSweet Talker board make up the am-

CENTRONICS - COMPA TIBL EPARALLEL PRINTER PORT

SWEET TALKERSPEECH SYNTHESIZER

Dl02D304D5D607D8

DATA STROBE

3

13„

5

17.

7

14

9

1Bm.

11

15«.

13

»,

15

20»

17

16-

BUSY

UNIT SELECTGND

EXTENDER

I 100/is |

L

7

P0

PI

P2

P3P4P5II12

STB

A/R

r

jb:

Q.

—, L.

^

1

1

D

pi®

ENABLE ( ()

GND r~ n

[7777|(@M[H]

r

ds Q>—4

L.

NOTE: THIS PULSE EXTENDERIS REQUIRED ONLY IF DATASTROBE IS LESS THAN 100MICROSECONDS LONG.

+5V AND +12VPOWER SUPPLY

H%

._!

Figure 5: Diagram of the connections between a Centronics-compatible parallel printerport (as on a TRS-80 Model 1 or III) and the Sweet Talker circuit board. Note that onsome computers the Unit Select line may need to be connected to +5 V.

plifier and filter sections. CapacitorsCl and C2 and resistors R5 and R6form a simple low-pass audio filter.The audio signal is then amplified byan LM386 1-watt amplifier (IC5) todrive an 8-ohm speaker directly.Potentiometer R7 controls thevolume, and the speaker connects tothe 2-pin connector on one corner ofthe board.

The board operates on power-supply voltages of +5 V and Vp. V,can be any voltage between +7 and

+ 14 V. I generally use +12 V.Power can be applied either throughthe edge connector or the 4-pin powerheader. Pin assignments on the powerheader are arranged exactly the sameas those on the Z8-BASIC Microcom-puter board presented in my last twoarticles, and the Sweet Talker boardcan conveniently use the same powersupply. (See "Build a Z8-Based Con-trol Computer with BASIC," July1981 BYTE, page 38 and August 1981BYTE, page 50.)

September 1981 © BYTE Publications lnc 45

Table 2: A list

of useful words with their Votrax-notation phonemes, for ease in

program coding.

Word

Phonemes

Word

Phonemes

A

A1, AY, Y

keyboard

K, AY, Y, B, 01,02, R, D

able

A1, Y, B, UH3, L

kill

K, 11, 13, L

about

UH1, B, UH2, AH2, U1,T

knowledge

N, AH1, UH3, L, 13, D, J

actual

AE1, EH3, K, T, CH, U1, UH3, L

add

AE1, EH3, D

L

EH1, EH3, UH3, L

adjust

UH1, D, J, UH1, UH3, S, T

language

L, AE1, EH3, NG, G, W, 11, D, J

large

L, AH1, R, D, J

B

B, E1, Y

left

L, EH1, EH3, F, T

back

B, AE1, AE1, K

length

L, EH1, EH3, NG, TH

basic

B, A1, Y, S, 12, K

listen

L, 11, 13, S, 12, N

been

B, EH1, EH3, N

before

B, Y, F, 02, 02, R

M

EH1, EH2, M

better

B, EH1, EH3, T, ER

make

M, A1, AY, Y, K

many

M, EH2, EH2, N, Y

C

S, El, Y

match

M, AE1, EH3, T, CH

came

K, A1, AY, Y, M

memory

M, EH1, EH3, M, ER, Y

can

K, AE1, EH3, N

message

M, EH1, EH3, S, 12, D, J

car

K, AH2, UH3, R

catalog

K, AE2, EH3, DT, UH3, L, AW2, AW2, G

N

EH1, EH2, N

change

T, CH, A1, AY, Y, N, D, J

name

N, A1, AY, Y, M

near

N, AY, 11, R

D

D, E1, Y

need

N, El, Y, D

data

D, A2, Y, DT, UH1

next

N, EH1, EH3, K, PAO, S, T

date

D, A2, AY, Y, T

none

N, UH1, UH3, N

decide

D, Y, S, AH2, EH3, Y, D

decision

D, Y, S, 12, ZH, UH3, N

0

02,01, U1

deliver

D, Y, L, 12, V, ER

object

UH1, B, D, J, EH1, EH3, K, T

obsolete

AH1, UH3, B, S, UH3, L, AY, Y, T

E

E1, Y

often

AW2, AW2, F, 13, N

early

ER, R, L, Y

omit

01, U1, M, 11, I3,T

either

E1, Y, THV, ER

other

UH1, UH3, THV, ER

empty

EH2, EH3, M, P, T, Y

end

EH2, EH3, N, D

P

P, E1, Y

exact

EH2, EH3, G, PAO, Z, AE2, EH3, K, T

package

P, AE1, EH3, K, 11, D, J

paper

P, A1, Y, P, ER

F

EH1, EH2, F

part

P, AH1, R, T

fact

F, AE2, EH3, K, T

person

P, ER, S, UH1, N

fault

F, AW, L, T

phone

F, 01, U1, N

final

F, AH2, Y, N, UH3, L

first

F, ER, R, S, T

Q

K, Y1, IU, U1, U1

follow

F, AH1, AW2, L, 01, U1

qualify

K, W, AW1, L, 11, F, AH1, EH3, Y

quantity

K, W, AH1, N,T, 13, T, Y

G

D, J, E1, Y

question

K, W, EH1, EH3, S, T, CH, UH3, N

game

G, A2, AY, Y, M

quick

K, W, 11, 13, K

good

G, 001,001, D

quiet

K, W, AH1, EH3, AY, 12, T

great

G, R, A2, Y, T

ground

G, R, AH1, UH3, W, N D

R

AH1, UH2, ER

grow

G, R, 01, U1

raise

R, A1, AY, Y, Z

reach

R, E1, Y, T, CH

H

A1, AY, Y, T, CH

ready

R, EH1, EH3, D, Y

hand

H, AE1, EH3, N, D

remain

R, E1, M, A1, AY, Y, N

have

H, AE1, EH3, V

resistor

R, E1,Z, 11, S, T, ER

hear

H, AY, 13, R

heavy

H, EH1, V, Y

S

EH1, EH2, S

high

H, AH1, EH3, Y

safe

S, A1, AY, Y, F

sale

S, A1, A2, AY, UH3, L

1

AH1, EH3, 13, Y

schedule

S, K, EH1, EH3, D, J, IU, U1, L

important

11, 13, M, P, 02, 02, R, T, EH3, N, T

scrap

S, K, R, AE1, EH3, P

include

11, 13, N, K, L, IU, U1, U1, D

section

S, EH1, EH3, K, SH, UH3, N

inform

11, 13, N, F, 02, 02, R, M

insert

11, N, S, R, R, T

T

T, E1, AY, Y

instead

11, 13, N, S, T, EH1, EH3, D

talk

T, AW, K

technical

T, EH1, EH3, K, N, 13, K, UH3, L

J

D, J, EH3, A1, AY, Y

terminal

T, ER, M, EH3, N, UH2, L

job

D, J, AH1, UH3, B

think

TH, 11, 13, NG, K

join

D, J, 01, UH3, 13, AY, N

time

T, AH1, EH3, Y, M

joy

D, J, 01, UH3, 13, AY

judge

D, J, UH1, UH2, D, J

U

Y1, IU, U1, U1

jump

D, J, UH1, UH2, M, P

under

UH2, UH2, N, D, ER

uniform

Y1, IU, U1, N, 13, F, 01, R, M

K

K, EH3, A1, AY, Y

until

UH2, UH2, N, T, 11, 13, L

keep

K, E1, Y, P

up

UH1, UH2, P

key

K, E1, Y

urgent

R, R, D, J, 13, N,T

46 September 1981 © BYTE Publicaripns Inc

Table 2 continued:

Word

Phonemes

Word

Phonemes

us

UH1, UH2, S

when

W, EH1, EH3, N

use

Y1, 111, 111, U1, Z

wherewhich

W, EH3, A2, EH3, RW, 11, 13, T, CH

V

V, E1, AY, Y

while

W, AH1, EH3, 11, UH3, L

vacant

V, A1, Y, K, EH3, N, T

whiskey

W, 11, 13, S, K, AY, Y

valid

V, AE1, UH3, L, 11, D

white

W, UH3, AH2, Y, T

value

V, AE1, EH3, L, Y1, IU, U1

who

H, IU, U1, U1

vendor

V, EH1, EH3, N, D, ER

will

W, 11, 13, L

vent

V, EH1, EH3, N, T

window

W, 11, N, D, 01, U1

verify

V, EH1, R, 13, F, AH1, EH3, Y

winter

W, 11, 13, N,T, ER

very

V, EH1, R, Y

wire

W, AH1, EH3, AY, R

via

V, E1, AY, UH2, UH3

with

W, 11, I3.TH

victor

V, 11, 13, K, T, ER

withdraw

W, 11, 13, TH, D, R, AW

voice

V, 01, UH3, 13, AY, S

without

W, 11, I3.TH, UH2, AH2, U1,T

void

V, 01, UH3, 13, AY, D

word

W, ER, R, D

volt

V, 02, 02, L, T

work

W, ER, R, K

volume

V, AH1, UH3, L, Y1, IU, U1, M

wrong

R, AW, NG

W

D, UH1, B, UH3, L, Y1, IU, U1

X

EH1, EH2, K, PAO, S

wage

W, A1, AY, Y, D, J

X-ray

EH1, EH2, K, PAO, S, R, A1, 13, Y

wait

W, A1, AY, Y, T

want

W, AH1, UH3, N,T

Y

W, AH1, EH3, 13, Y

was

W, UH1, UH3, Z

Yankee

Y1, AE1, EH3, NG, K, E1, Y

wash

W, AW, SH

yard

Y1, AH1, R, D

water

W, AH1, UH3.T, ER

year

Y1, AY, 13, R

watt

W, AH1, UH3, T

yellow

Y1, EH1, EH3, L, 01, U1

wave

W, A1, AY, Y, V

yes

Y1, EH3, EH1, S

we

W, E1, Y

yesterday

Y1, EH3, EH1, S, T, ER, D, A1, 13,

Y

weapon

W, EH2, EH2, P, UH1, N

yet

Y1, EH1, EH3, T

Wednesday

W, EH1, N, Z, D, A1, 13, Y

your

Y, 02, 02, R

week

W, E1, Y, K

weigh

W, A2, A2, Y

Z

Z, E1, Y

went

W, EH1, EH3, N, T

zap

Z, AE1, EH3, P

west

W, EH1, EH3, S, T

zero

Z, AY, 11, R, 01, U1

wet

W, EH1, EH3, T

zone

Z, 01, U1, N

what

W, UH3, UH1.T

zulu

Z, IU, U1, L, IU, U1

wheel

W, E1, Y, L

Speaking in Phonemes

Table 1 lists the 64 basic phonemesof the English language. At firstglance, it appears complicated, but itis easy to understand and use. Takethe word "call," for example. It ismade up of three distinct phonemes,as follows (expressed in Votrax nota-tion):

K, AW, L

which correspond to the hexadecimalcodes:

19 3D 18

Similarly, the word "disk" is brokeninto the phonemes:

D, II, S, K

which correspond to the hexadecimalcodes:

IE OB IF 19

See reference 3 for more details onthis process.

Causing the synthesizer to speakeither of these words is done simplyby sending the hexadecimal codes se-quentially to it. This is most easilydone through a parallel I/O portunder control of a program written inBASIC. Typically, if the synthesizerwere connected to port 0 on yourcomputer, the routine for saying"call" would be coded as follows:

100

110

130140

150

150

DATA 25, 61, 24 :REM

Decimal Phoneme codes for

"call"

FOR A = l TO 3 : READ P(A)

:NEXT A

F0RA = 1T0 3

OUT 0,P(A) :REM Latch

Phoneme code into SC-01

IF INP(0) = 0 THEN GOTO

:REM Continue if A/R not busy

160 NEXT A

170 OUT 0,63 :REM Send STOP

code to SC-01180 END

Essentially any word or series ofwords can be spoken using thismethod. It isn't necessary for you toacquire special knowledge aboutword sounds to use a phonetic speechsynthesizer, because many lists ofword and phoneme equivalents areavailable. Table 2 is a list of somecommon words. A more extensive listis in preparation.

Easy Interfacing

What could be easier than pretend-ing that the Sweet Talker speech syn-thesizer is a parallel-interfacedprinter? It just so happens that manycomputers already have a paralleloutput port in the form of aCentronics-compatible parallelprinter port. This connection is avail-

September 1961 © BYTE Publications Inc 47

Number

Type

+ 5V

GND

-12V

+ 12V

IC1

COM5016

2

11

9

IC2

COM2017

1

3

2

IC3

CD4049

1

8

IC4

MC1489

14

7

IC5

MC1488

7

1

14

RS-232 CONNECTOR

|~~ DB-25-1

SWEET TALKERCONNECTIONS

(TJ>PO

Figure 6: Schematic diagram of a serial I/O interface for the Sweet Talker board, to be used in place of parallel I/O. The serial com-munication protocol is RS-232C.

able on all Radio Shack TRS-80Model III and expanded Model I com-puter systems, as well as manyothers. By connecting the SweetTalker board as shown in figure 5, itis possible to fool the computer intothinking that the Sweet Talker is aprinter, whereupon we can useLPRINT statements to drive it. Thesame machine-language routine in theBASIC interpreter that normallytransfers ASCII (American StandardCode for Information Interchange)character strings to the printer willalso work with the speech synthe-

A BASIC LPRINT statement willtransmit any ASCII characters be-tween the double quotes (except thequotation marks themselves and per-haps a few control codes) whetherthey spell out something humanlycoherent or not. As table 1 illustrates,all of the phonemes correspond toASCII characters which produce theequivalent 6-bit code (the lowercaseletters "a" through "z" correspond tohexadecimal codes 21 through 3A). Itis possible, therefore, to type an "@"for the EH3 phoneme (hexadecimalcode 00) or a "> " for PA1 (hexadeci-mal code 3E). Using this technique,

the program statement for saying"call" would be:

100 LPRINT "Y = X"

It's a good idea to add a stop pho-neme (corresponding to ASCII "7")after the end of the word to cancel thelast phoneme. The line then becomes:

100 LPRINT "Y=X";"7";

The Sweet Talker speech synthe-sizer attaches to and handshakes withthe computer in the same manner as aprinter would. The A/R output is

48 September 1981 © BYTE Publications Inc

Circle 266 on inquiry card.

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connected to the Busy input, and theUnit Select line is grounded to simu-late printer attachment. The SweetTalker's Enable input should also begrounded. The computer's LPRINTdriver routine sends one character tothe "printer" (speech synthesizer) andthen checks the Busy line before send-ing another. When the Busy line ishigh again, the next character (pho-neme) is sent.

The only area for concern is thepulse width of the data strobe (at-tached to Jl pin 21 with jumper JPlinstalled), as I previously mentioned.If it is less than 100 /is, a type-74121monostable multivibrator should beadded as indicated in figure 5. If youare unsure of the duration, add thecircuit anyway.

Once the interface is attached, asimple program can be used to testphoneme combinations. For example,sending "S*1L/@*KY" will cause theunit to say "automatic," and"Y2M*KIMB677" will make it say"continue." A simple test program re-quires only three lines:

100 INPUT A$110 LPRINT A$;"7";120 GOTO 100

Using a Serial Interface

Your computer might not have aparallel printer port, but a serial oneinstead. While the interface is morecomplicated, you can also use

LPRINT statements to drive the addi-tional circuitry shown in figure 6.This circuit is a full-duplex RS-232Cserial interface which is capable of re-ceiving a phoneme transmitted serial-ly from the computer, converting itback to parallel form, and strobing itinto the SC-01.

The timing relationships betweenthe interface and the computer be-come slightly more complex. When-ever a phoneme is loaded into theSC-01, the A/R line drops and theRS-232C Data Terminal Ready signalgoes low. After the phoneme has con-cluded, the UART (universal asyn-chronous receiver/transmitter) trans-mits a jumper-selected character (op-tionally preset on UART pins 26through 33) and raises the Data Ter-minal Ready line again. Proper tim-ing from the host computer can be ac-complished either by sending suc-cessive characters only in response tothe "phoneme-concluded" code or bymonitoring the state of the Data Ter-minal Ready line.

The communication rate betweenthe host and the synthesizer is switch-selectable from 50 to 19,200 bps usingthe COM5016 data-rate generator asshown. Communication is hard-wireselected for 8-bit data words, no pari-ty bit, and 1 stop bit. A more in-depth discussion of the data-rate gen-erator and UART was given in one ofmy previous Circuit Cellar articles("I/O Expansion for the TRS-80, Part

These items are available from:The MicroMint Inc917 MidwayWoodmere NY 11598Telephone:

(800) 645-3479 (for orders)(516) 374-6793 (for technical infor-mation)Votrax SC-01 Speech Synthesizer Chip

(single integrated circuit) $70

(5 or more, price each) $55

Sweet Talker Phonetic Speech Syn-thesizer, parallel-port version. IncludesSC-01 integrated circuit, data sheet,and user's manual.Assembled and tested $239

Sweet Talker Phonetic Speech Syn-

thesizer, Apple II plug-compatible ver-sion. Includes SC-01 integrated circuit,data sheet, and user's manual,(separate power supply not required)Assembled and tested $149

MicroMint 3-voltage power supply(size 2% by 4Vz inches)Provides: +5 V, 300 mA+ 12 V, 50 mA-12 V, 50 mA(-12V not required by Sweet Talker)

Assembled and tested $35

All printed circuit boards are solder-masked and silk-screened. Please in-clude $2 for shipping and handling onany order. New York residents pleaseinclude 7% sales tax.

2: Serial Ports," June 1980 BYTE,page 42).

In Conclusion

What can you do with a computer-controlled speech synthesizer? I'msure you have a few ideas. In anycase, the benefits of electronic speechsynthesis will surely propagate asmore people learn how to use it.

Next Month:

A discussion of EPROM program-ming and the design of an intelligentEPROM programmer. ■

References

1. Ciarcia, Steve. "Build a Low-Cost Speech-Synthesizer Interface," BYTE, June 1981,page 46.

2. Ciarcia, Steve.' 'Talk to Me: Add a Voice toYour Computer for $35," BYTE, June

1978, page 142, reprinted in Ciarcia's Cir-cuit Cellar, Volume I. Peterborough NH:BYTE Books, 1979, page 77.

3. Fons, Kathryn and Tim Gargagliano. "Ar-ticulate Automata: An Overview of VoiceSynthesis," BYTE, February 1981, page164.

4. Gargagliano, Tim and Kathryn Fons. "TextTranslator Builds Vocabulary for SpeechChip," Electronics, February 10, 1981,page 118.

5. Gargagliano, Tim and Kathryn Fons. "TheTRS-80 Speaks: Using BASIC to Drive aSpeech Synthesizer," BYTE, October

1979, page 113.

6. Gargagliano, Tim and Kathryn Fons. "AVotrax Vocabulary," BYTE, June 1981,page 384.

7. Lin, Kun-Shan, Gene Frantz, and KathyGoudie. "Software Rules Give PersonalComputer Real Word Power," Elec-tronics, February 10, 1981, page 122.

8. Weinrich, David W. "Speech-SynthesisChip Borrows Human Intonation," Elec-tronics, April 10, 1980, page 113.

9. Wiggins, Richard and Larry Brantingham."Three-Chip System Synthesizes HumanSpeech," Electronics, August 31, 1978,page 109.

Editor's Note: Steve often refers to previousCircuit Cellar articles as reference material forthe articles he presents each month. These ar-ticles are available in reprint books from BYTEBooks, 70 Main St, Peterborough NH 03458.Ciarcia's Circuit Cellar covers articles that ap-peared in BYTE from September 1977 throughNovember 1978. Ciarcia's Circuit Cellar,Volume II presents articles from December1978 through June 1980.

50 September 1981 © BYTE Publications Inc

Meet HP Series 80:HewlettrPackard's newone-on-onecomputing systems for professionals.

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System Review

The Big Board

A Z80 System in Kit Form

David Thompson11740 NW West RdPortland OR 97229

I built the computer on which I'm writing this article.Even though I'm no expert at computer hardware or soft-ware, I assembled this system in a matter of weeks, begin-ning with a kit called the Big Board.

Manufactured by Digital Research Computers ofTexas, the Big Board is a single-board computer thatpacks an impressive set of features into an inexpensivepackage. By not providing the cabinet, power supply,keyboard, monitor, and disk drives, Digital Research cansell this heart of a powerful Z80-based system for $650 inkit form. For an additional $50, the board comes with allthe sockets soldered in place—a real convenience since allthe integrated circuits are socketed.

The board is the size of an 8-inch disk drive. It includes64 K bytes of programmable memory, a 24-line by80-character video generator, a keyboard interface, room

Photo 1: The Big Board kit as the author received it. The boarditself is in the center, with the documentation partly beneath it.On each side are plastic bags containing parts. Cables with con-nectors are in the rear.

for four 2 K-byte ROMs (read-only memories, "bankswitched" along with the video memory), and a floppy-disk drive controller. Options include parallel and serialports and an on-board timer.

History

About three years ago, J B Ferguson, an electrical engi-neer from Dallas, wire-wrapped together a Z80-based,single-board computer and showed it to Jim Tanner ofDigital Research. They then worked together to design apowerful, yet inexpensive, unit.

Because of the small size of the board, they used LS(low-power Schottky) parts to keep heat problems to aminimum. According to Tanner, this choice almost killedthe project. As recently as January 1980, LS parts werevery expensive—too expensive, Tanner and Fergusonbelieved, for the Big Board to be salable. However, pricesdropped so substantially before the end of that year, forboth the LS parts and the memory, that Tanner andFerguson decided to market the unit with a full 64 Kbytes of user memory.

Russell Smith designed the Big Board's monitor ROMand the custom BIOS (basic input/output system) forCP/M. The initial plan was to offer CP/M 1.4 with theboard. But when version 2.2 became available, Smithwent back to work and revised the BIOS. Source listingsfor both the monitor and BIOS are available free fromDigital Research. Just ask for them when ordering the kit.

The Kit

The quality of the circuit board is readily apparent. Itis solder-masked and tinned, which makes solderingeasy. Solder-masking covers all the metal on the boardexcept for spots where leads will be soldered. The compo-nent outlines and numbers are silk-screened on the top,and the holes for the component leads are plated through(they have metal deposited inside them to insure goodconnections).

52 September 1981 © BYTE Publications Inc

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The end user wants State-of-the Art when he buys a 64K board.So we had our super designer put together the 64K board of thefuture with tomorrow's high speed processors in mind. This boardhad to work with all S-100 systems, with current processors andfuture (up to 8 MHz) processors. It had to be ultra-low power. It hadto be designed so the advanced user could populate the board withprogrammed EPROMs for special applications. This board, too, hadto have both bank select and extended addressing at no extra cost.The board was also designed to be used as a 32K or 48K board andwe are selling it that way, too. Put in additional chips when youwant to increase the capacity!OEM and dealer inquiries invited.

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Other hardware features

Big Board

Parallel port for ASCII-

encoded keyboard;

Manufacturer

24-line by 80-character video

Digital Research Computers

generator (composite or

of Texas

separated sync)

POB 401565

Garland TX 75040

Options

(214) 271-3538

Real-time clock;

two RS-232 serial ports;

Price

two parallel ports

Bare board with the monitor

(adding the options is simply

and character ROMs, $195

a matter of plugging in the

Complete kit with sockets

devices and adding a few

and ICs, $649

resistors and capacitors)

Complete kit with sockets

already soldered in place;

Software

$699

2 K-byte monitor ROM

(comes with the kit);

Dimensions

CP/M 2.2 is available com-

8.5 by 13 inches

pletely configured for an

additional $150

Processor

Z80A

Comments

Putting the kit together re-

System clock frequency

quires some experience

2.5 MHz

handling static-sensitive

parts and a soldering iron.

Memory

Some knowledge of 8080 or

64 K-byte dynamic

Z80 machine language or

programmable memory;

assembly language is

four 2 K-byte ROMs

important.

(bank switched);

Be sure to ask for a listing

4 K-byte static video

of the ROM monitor and

memory (bank switched)

the BIOS (basic input/out-

put system) when ordering

Mass storage

your board. The listings are

On-board controller for up

free for the asking.

to four 8-inch floppy-disk

drives (single-density; each

disk holds 240 K bytes for-

matted)

Although the Big Board's documentation is not as de-tailed or well organized as Heathkit's, it is well writtenand contains the information needed. The assembly pro-cess is explained step by step, complete with boxes youcan check off. Because the parts' names and outlines arestenciled in place, the process takes only a few hours.

What You Must Know

If you have had a high school electronics class, cansolder with a small iron, and know how to handle static-sensitive parts, you should have little trouble building theBig Board. But there is more to getting a system runningthan simply building the board. Though the Big Board iswell designed and easy to interface with the keyboard,video monitor, and disk drive, interfacing with otherperipheral devices requires some understanding of thehardware, the monitor, and the operating system. For in-

54 September 1981 © BYTE Publications Inc

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stance, to interface a modem or printer, you will needsome assembly code. Until you write code to convincethe Big Board that something else out there "understands"it, it will continue to output everything to the screen. For-tunately, there is a vast, growing national user's group tohelp you bring up and interface the Big Board.

When I received this board, I didn't understand operat-ing systems and had never written anything in assemblylanguage. Part of the reason I got the Big Board was tolearn these things. It was an incredible feeling, afterbuilding the board, to watch the operating system signon, and later to see the first lines of text rasp their wayacross the printer platen. I knew that I would never againhave to update listings by hand while seeing the latestversion on the video monitor.

Photo 2: The empty printed-circuit board. Location markingsand some circuitry are visible.

Photo 3: Close-up of the printed-circuit board showing all theparts in place.

Photo 4: The Big Board in place in the author's system. Restingon top of the cabinet is the power supply, originally built for aDigital Equipment Corporation controller.

And Once It's Running

Once it's running, what can the Big Board do7 TheROM-based monitor program that comes with the boardgives you access to all the user memory and ports, letsyou test memory to verify that it is operating properly,and lets you look at specific tracks and sectors on disks. Ifyou purchase the custom CP/M 2.2 available with theboard, you gain access to a world of utilities, languages,games, and applications programs.

The Big Board is also electrically versatile. If you con-nect a standard terminal to the serial port (RS-232), thecomputer will make that port its standard input/outputinterface. Or if you are using a separate keyboard andvideo unit, you can select an output video signal to matchalmost any monitor made. The manual contains com-plete information on setting jumpers, including an exam-ple for the standard composite video monitor.

How well does the Big Board work? So well that myonly real complaint, dealing with the character set, hasalready been corrected. The vast majority of people whohave bought one have had no problems. Considering thecomplexity of the Big Board, this is a remarkable achieve-ment.

Conclusions

If you are interested in building a powerful system, orin learning what goes on in the "engine room" of a micro-computer, or if you've ever had the urge to push thelevers, blow the whistle, and increment the A register,Big Board is certainly one way to do it. When you getdone, you'll have a truly personal system for less thanhalf the price of a "canned" system. And your system willbe able to perform complex tasks like text editing. I usemy Big Board for all my writing at home, including let-ters to relatives, notes to myself, and this article.■

The author is now publishing Micro Cornucopia, a magazine aboutthe Big Board. The magazine appears bimonthly at an annual subscrip-tion rate of $12. For further information, send a SA5E to David Thomp-son, 11740 NW West Rd, Portland OR 97229.

56 September 1981 © BYTE Publications Inc

MORROW O

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Experience. As of April, 1981,there were over fifteen hun-dred Morrow Designs hard disksystems successfully installed.In fact, over 200 independentsystems integrators now useour hard disks to solve theirmass storage problems.Performance answers. MorrowDesigns hard disk systems havebeen benchmarked against allother systems. None is fasterunder CP/M. Morrow Designshard disks operate at 10 timesthe speed of a floppy diskdrive. Transfer rates range from590,000 bytes to 900,000 bytesper second. That kind of perfor-mance can become addictive.Cost effective answers. CompareMorrow prices and performanceto anything presently availablefor S-100 systems. You'll findMorrow's price/megabyte/performance ratio to beunmatched. Leadership indisk systems technologyearned us leadership inprice/performance. Andthat may have earned usa call from you. Circle theReader Service Numberforourfull line data sheets.Can't wait? Call us at (415)And yes, OEM quantity prices are

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The Xerox Alto Computer

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In the mid-1970s, the personal-computer market blossomed with theintroduction of the Altair 8800. Eachyear since has brought us personalcomputers with more power, fasterexecution, larger memory, and bettermass storage. Few computer en-thusiasts or professionals can look atthe machines of today withoutwondering: What's next?

The Alto: a Personal Computer

In 1972, Xerox Corporation de-cided to produce a personal computerto be used for research. The resultwas the Alto computer, whose namecomes from the Xerox Palo AltoResearch Center where it wasdeveloped. The Alto was the result ofa joint effort by Ed McCreight,Chuck Thacker, Butler Lampson,Bob Sproull, and Dave Boggs, whowere attempting to make a devicethat was small enough to fit in an of-fice comfortably, but powerfulenough to support a reliable, high-quality operating system andgraphics display. Their goal was toprovide each user with a personalcomputing facility capable of meetingall individual needs and a corn-

Acknowledgments

/ would like to thank Dr Brian Reid andMark Roberts of Stanford University for theirtime and helpful comments; also Sandy Lan-zarotta of Xerox and Cindy Pavlinac for theirhelp and support.

Photo 1: Two of the Xerox Alto personalcomputers. Each Alto processor is madeof medium- and small-scale TTL in-tegrated circuits, and is mounted in a rackbeneath two 3-megabyte hard-disk drives.Note that the video displays are tallerthan they are wide and are similar to apage of paper, rather than a standardtelevision screen.

munications facility that would allowusers to share information easily.

In 1978, Xerox donated a total offifty Altos to Stanford, Carnegie-Mellon, and MIT (Massachusetts In-stitute of Technology). Thesemachines were quickly assimilatedinto the research community andrapidly became the standard againstwhich other personal computers werejudged.

It is unlikely that a person outsideof the computer-science researchcommunity will ever be able to buyan Alto. They are not intended forcommercial sale, but rather asdevelopment tools for Xerox, and sowill not be mass-produced. What

makes them worthy of mention is thefact that a large number of the per-sonal computers of tomorrow will bedesigned with knowledge gained fromthe development of the Alto.

The Hardware

The Alto consists of four majorparts: the graphics display, thekeyboard, the graphics mouse, andthe disk storage/processor box. EachAlto is housed in a beautifullyformed, textured beige metal cabinetthat hints at its $32,000 price tag.With the exception of the diskstorage/processor box, everything isdesigned to sit on a desk or tabletop.

The Graphics Display

The graphics display is the moststriking feature of the Alto. It lookssomewhat like a television screen thathas been turned sideways (see photo1). It is a raster-scan display, and thephysical dimensions of the screen are8 inches (horizontal) by 10 inches(vertical). The black-and-whitedisplay allows the user to address anarea 808 pixels (picture elements) ver-tically by 606 pixels horizontally.This results in resolution of about 80points per inch.

The method of display used iscalled bit-mapped raster scan. Thismeans that every point on the displayis addressable as a bit in memory.Although this method can take up agreat deal of memory, it has the ad-vantage of making the display very

58 September 1981 © BYTE Publications Inc

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BYTE September 1981 59

fast. Bit mapping also provides theuser with a convenient method ofscreen access and the ability to easilylook at the current contents of thescreen.

In terms of displaying text, thescreen can hold 60 lines of 90characters (assuming the charactersare equivalent to the typical 7 by 9dot character commonly found onmost video terminals). Charactergeneration is not done in hardware onthe Alto. A character set may becreated by a user and displayed onthe screen. Mixed fonts are allowedso that text of various sizes andshapes may be simultaneouslydisplayed on the screen.

Since each dot on the display cor-responds to only one bit in memory,there is no facility for grays or inter-mediate intensities. Due to the largenumber of points per inch, however,various combinations of points canbe displayed to form a "texture" thatgives the impression of varyingshades of gray. This is exactly thesame method used to reproduce pic-tures in a newspaper.

The Keyboard

Superficially, the Alto keyboardresembles a typical typewriterkeyboard with /the addition of a fewspecial keys. The keyboard isdetachable, and quite comfortable fortyping. It has the unique property ofbeing entirely unencoded. Each keyhas its own signal line in the

Photo 2: Display from the keyboara-testprogram. The Alto keyboard has aseparate signal line for each key and canthus tell when any number of keys arebeing pressed simultaneously. In thedisplay, the black keys are being helddown. The small square above thekeyboard represents the mouse (see photo4); one mouse key is also pressed.

Photo 3: The Pinball game. Flippers areactuated by the two shift keys; an Altoport can be connected to a speaker to pro-vide bells and buzzer sounds.

keyboard interface, which allows aprogram to take advantage of thepossibility of "chord" commands,where the user holds down one ormore keys. For example, Shift-Control-E is as easy for the Alto toread as A-B-C (see photo 2). Anotheradvantage is the ability to determinehow long a key has been held down.For example, the pinball game pro-gram in photo 3 determines the forceof a shot by measuring how long akey is held down on the keyboard.There is, of course, software to allowa program to read the keyboard in thetypical manner.

The Graphics Mouse

The mouse is a small box with threebuttons on the top and several ballbearings on the bottom. A slendercable connects the mouse to the Altokeyboard (see photo 4). The buttonsare named red, yellow, and blue,although the physical buttons are allblack. The mouse is typically held inthe user's right hand and rolled alongthe table on a soft piece of plasticthat provides traction for the ballbearings.

Movement is detected by the mo-tion of one of the ball bearings. Themouse reports changes in position tothe Alto. From this, a cursor on theAlto display can be positioned. Thephysical position of the mouse on thetable is unimportant, since only thechange in position is reported. Themouse graphics interface is con-siderably more flexible and comfor-table than a bit pad, joystick, ortrackball. Many Alto programs canbe controlled with the mouse alone,independent of a keyboard.

The buttons on top of the mouseare also unencoded, for flexibility.Many programs distinguish betweenholding a mouse button on or clickingit on and off. This allows a programto receive input by moving the cursorto some designated spot on the screenand then touching a mouse button tomake something happen.

Disk Storage/Processor Box

The processor and disk storage forthe Alto are contained in a rack aboutthe size of a waist-high filing cabinet.Each Alto has two 3-megabyte diskdrives. The drives themselves resem-ble small pizza ovens and are oftenreferred to in this manner.

The "brain" of the Alto is a 16-bitcustom-made processor intended toresemble the Data General Nova1220. The processor is made entirelyof small- to medium-scale TTL(transistor-transistor logic) ICs (in-tegrated circuits). The processoroperates at a speed of approximately400,000 instructions per second. EachAlto has an address space of 64 K16-bit words, including the graphicsbitmap. By using a technique calledbank selection, the Alto may expandits available memory in 64 K-wordincrements up to 256 K words. AnAlto with 256 K words is known as awide-bodied Alto.

Quite a bit of the magic of the Altois performed at the microcode level.The Alto can run up to sixteen tasksconcurrently, and all of the schedul-

Photo 4: The mouse input device. Theoperator uses the mouse to control cursorplacement on the screen; it detects its ownchange in position (a joystick relies on ab-solute position) as the operator rolls itaround on a piece of soft plastic. Themouse also has three buttons, called red,yellow, and blue.

60 September 1981 © BYTE Publications Inc

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ing and I/O (input/output) for thismultiprocessing is done in microcode.The user has direct control over onlyone task, however. The user task isthe lowest priority and must, ifnecessary, relinquish processingcycles to the other tasks that controlthe display, disks, keyboard andmouse I/O, and Ethernet connec-tions. The user has direct control overthe microcode and may rewrite itaccording to individual taste.

The Software

The Alto has the interesting prop-erty of using software (oftenmicrocode) to perform many tasks,such as keyboard encoding andcharacter generation, that are typi-cally done in hardware. This ap-proach leaves the Alto with an occa-sionally cumbersome but highly flexi-ble architecture.

Each Alto has a ROM (read-onlymemory) that contains just enoughsoftware to "bootstrap" an Alto intothe local network (see textbox on thispage). By keeping a bootstrap pro-gram in ROM, the user will alwayshave a "safety net" to fall back on incase some other portion of the systemsoftware is not working. All of theAlto software can be retrieved fromacross the network.

The Alto Operating System (OS), aprogram which provides a set of basicfacilities for control and communica-tion with the Alto, is written inBCPL, a language very similar to C.Most programs, BCPL or otherwise,run under the direction of the AltoOS. Since the address space of anAlto is small, a technique called a"Junta" is used to permit BCPL pro-grams to shed unwanted sections ofthe Alto OS during execution. Ifthose portions are needed later, theymay be restored by performing a"Counterjunta."

One BCPL program that runs ontop of the operating system is calledthe Alto Executive (see photo 5a).This program speaks to the userdirectly and makes facilities availablefor file manipulation and program ex-ecution. An interesting feature of theExecutive is that of escape expansionand file-name completion. Typing apartial file or program name followed

by an escape, in the same fashion thatan ESC (escape) or ALT (alternatemode) might be sent from an ASCII(American Standard Code for Infor-mation Interchange) terminal, causesthe Executive to complete the typingof the name on the screen. This

allows a programmer to name a file ina descriptive manner (such asGatewaylnformation.press), ratherthan typing in a long name. The Ex-ecutive program will recognize it assoon as it has read enough charactersto determine the file uniquely. By

The Ethernet Network: Interconnecting Personal Computers

The Ethernet network, developed atXerox Palo Alto Research Center byBob Metcalfe and Dave Boggs, is amedium for the transmission of infor-mation. It is a multiaccess broadcastsystem used to link many computersystems that are physically withinseveral hundred meters of each other.Each machine in the network is con-nected by means of a single, passive,coaxial cable.

The Ethernet network is a packetnetwork. Information to be trans-mitted from one node to another is en-closed in an "envelope" of data thatdescribes the information (ie: itslength, a checksum for error control)and describes the destination of theresulting datagram or packet.

Regulation of access to the Ethernetcable is performed by a systemdesignated CSMA/CD (Carrier SenseMultiple Access with Collision Detec-tion). This technique works in exactlythe same way that conversation amonga group of people at a party isregulated. A node with something tosay waits until no one else is speaking.When everyone else is quiet, that nodebegins to broadcast. If another nodealso starts broadcasting, this is called acollision. When a collision occurs, allof the nodes that are broadcastingcease to do so. Each node waits a ran-dom amount of time and then listensfor another lull, thus starting the wholeprocess again.

Each node on the network listens tothe beginning of each packet. Once anode has determined that a packet isnot addressed to itself, it stops payingattention to that packet and waits onlyfor the end of the packet to allow it toprepare to listen to the next one. AnEthernet node may become "pro-miscuous" and listen to all packets be-ing broadcast. This allows a veryprecise monitoring of statistics on theEthernet system, since nodesgenerating traffic need not performany statistical processing or use any

network bandwidth to report thestatistics. A "silent observer" canwatch the network without ever affec-ting the performance of that network.

At first glance, the "cocktail party"approach to multiple access mightseem awkward. A second look,however, reveals that the maximumpacket length is only 554 bytes, and thespeed of Ethernet transmissions is ap-proximately three million bits per se-cond. This leads to a maximumtransmission time of about 1.5 ms(milliseconds), which means that evenon a highly loaded network, theoverall efficiency remains very high.

An interesting aspect is that theEthernet network itself is entirelypassive. Regulation is done by each in-dividual node. This decentralizationmeans that the failure of any singlenode will not significantly affect thenetwork as a whole. Thus, the meantime between failures of the whole net-work is very high, making it a goodchoice for industrial or business ap-plications where downtime means lostrevenue.

The high speed of the Ethernet net-work rivals that of disk I/O. A filemay be loaded from across the net-work almost as easily as from a localdisk. In a distributed information pro-cessing system, it is highly desirable toallow a file to be easily accessedanywhere on the network. A high-speed file transfer capability also per-mits a new machine to be integrated in-to the network in just a few minutes.

The competition in local networkingis hot and heavy. DEC (Digital Equip-ment Corporation), Intel, and XeroxCorporation have recently joinedforces to promote an Ethernet-basedindustry standard network. WangCorporation, IBM, and Zilog have alsoproposed networking standards.Whatever the outcome, industry seemsto have decided that the future is inlocal networks.

62 September 1981 © BYTE Publications lnc

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typing a question mark instead of anescape, the Executive will list all filenames that are valid matches for thestring typed thus far.

The Alto has a highly flexible andrugged file system. Unlike many filesystems (eg: Digital Research's CP/Mor Radio Shack's TRSDOS) that limitnames to six or eight characters witha three-character extension, the Altofile system permits file names of up tothirty-one characters in length. Whena file name is entered for the firsttime, the file name is stored exactly astyped, even with regard to upper- andlowercase. Since the file names maybe very long, this permits a program-mer to use upper- and lowercase toimprove readability. LongFile-Name.BigExtension is much easier onthe eyes than LONGFILENAME.BIGEXTENSION. After the creation

of a file, case is ignored when the useris speaking about the file, so either ofthe two names in the previous ex-amples, as well as longfilename.bigextension, would be valid.

Alto files are divided into pages.Each page contains a small headerthat describes the current page, tellswhat file the page belongs to, andpoints to the places on the disk thatcontain the next and previous pagesfor the same file. This makes the filesystem almost indestructible. A pro-gram called Scavenger can auto-matically rebuild a broken filesystem.

Of course, no Alto is an island, sosoftware is needed to deal with theEthernet network. Some of this soft-ware appears in the form of theNetExecutive (see photo 5b) and FTP(file-transfer program). The NetExec

is a program that appears to be verysimilar to the Alto Executive, but itloads programs from across the net-work rather than from the local disk.This means that a user need not keepinfrequently used or large programslocally. Instead, these programs canbe loaded through the network (at anapparent speed of approximately800,000 bits per second) only whenneeded. FTP performs similar feats offile manipulation, but in a con-siderably more flexible manner.

Although a great deal of softwarewritten for the Alto is in BCPL, thereis a new contender for softwaredevelopment called Mesa. Mesa is aPascal-like language that is incom-patible with BCPL because of dif-ferences in their respectivemicrocodes. Mesa is expected to bethe programming language for thesuccessors of the Alto (see photo 5c).

BCPL and Mesa are the systemlanguages for the Alto, which meansthat the system utilities and many ap-plications programs are written inthem. Other languages are availableon the Alto, however. Much of theresearch work done on the Alto atXerox is written in Smalltalk, anobject-oriented language that is botheasy to learn and highly powerful (seethe special August 1981 BYTE issue(5e)

M Ull

Photo 5: Examples of Alto software. Photo 5a shows a display of the Alto Executive, with an example of star and question-marknotation. Photo 5b shows the NetExecutive (similar to the Alto Executive, but it allows access to resources on the Ethernet). Photo 5cis a typical Mesa program being edited by Bravo; note the different typefonts used in the program listing. Photo 5d is a directory fromthe Neptune directory editor. The file names in black have been selected for further operations such as printing or erasure. The cursoris displayed as a cross in a circle. Photo 5e illustrates Bravo's ability to change fonts (there are hundreds of fonts for the Alto, fromGothic to Elvish Runes; the central paragraph in this display has been changed to Greek). The document in the bottom window hasbeen converted to the form shown in the top window.

64 September 1981 © BYTE Publications Inc

Circle 233 on inquiry card.

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Photo 6: Use of the Draw program. In photo 6a, points are placed with the cursor, andcurves and lines are filled in by the program. Photo 6b shows that lines may be"painted" with a variety of "brushstrokes" (the cursor has changed to a small paint-brush). In photo 6c, texture is given to the lines; dotted lines are created with thescissors cursor. Photo 6d shows that the picture may be mathematically manipulated; anew figure may be created by reversing, tilting, or stretching a copy of the original.

on the Smalltalk language). Anothersupported language is LISP, a list-processing language that is verypopular in the artificial intelligenceresearch community.

Using the Screen

A system with the advancedgraphics capability of the Alto willmake extensive use of those facilities.The screen may be broken up intowindows, and each window may beaccessed in a different manner, if

desired. Many Alto programs useonly the mouse and screen windowsfor program control. For instance, theNeptune program is used for man-aging the contents of the Alto's localdisks (see photo 5d). A file may bedeleted simply by touching the filename with the cursor, then touchingthe Delete spot on the screen with thecursor. As the cursor enters a newwindow, it may change shape,perhaps appearing as an arrow in onewindow and a paintbrush in another.

Since the Alto is used extensivelyfor research in the office automationfield, a good text editor is an obviousrequirement. Bravo is a text editorand formatter widely used on theAlto. In the tradition of screen-oriented editors, the current state ofthe user's file is always shown on thescreen. Bravo is controlled partly bykeyboard commands and partly bymouse commands. It allows a user toopen windows into one or more files.Text may be added or deleted bypointing at the desired location on thescreen (see photo 5e) with the mousecursor, and giving a command via thekeyboard or mouse. Bravo supportsmany different fonts and allows theuser to change easily from one font tothe next. In addition, Bravoremembers the changes that havebeen made to a document and allowsthe user to reverse any or all changes.

Bravo allows the user to edit andformat text, but often a person maywish to include illustrations in adocument. To do this, a programcalled Draw is used. Draw is an in-teractive sketch-pad program thatprovides a variety of tools forcreating and manipulating picturesmade from lines, curves, and text.Draw divides the screen into anumber of windows (see photo 6).The left side of the screen contains amenu of commands and a variety ofbrushstrokes that can be selected.The top of the screen contains an areafor text commands and messagesfrom the program. The middle of thescreen is the picture workspace.Curves can be drawn by moving thecursor directly, or by selecting severalpoints and allowing Draw tomathematically fit a curve to thosepoints. Once an object is defined, itcan be repainted using a number ofbrushstrokes. Since this is verysimilar to the techniques used by ar-tists and calligraphers, quite a bit ofartistic expression is possible. Anobject can be duplicated, rotated,stretched, or shrunk, by means of asmall set of commands and mousegestures.

The Network

Each Alto is assigned an Ethernetaddress that identifies it uniquely on

66 September 1981 © BYTE Publications Inc

Circle 104 on inquiry card.

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Photo 7: The multiplayer Trek program.This game is played entirely under mousecontrol. The lower portion of the screenshows a short-range sensor scan; above isthe long-range display, and navigationand weapons controls.

the network. A typical Ethernet ad-dress might be 50#100, which ismeaningless to most people. To per-mit an easily remembered distinctionbetween Altos, each is assigned aname. For instance, the Altos at Stan-ford are named after rivers andmountains in California State parks;Altos at CMU are named after jewels,and Altos at Xerox are named afterpeople. This leads to such interestingnames as Cypress, Turquoise, orMachiavelli, which are considerablyeasier to remember than 50#100.

Alto networks do not consist en-tirely of Altos. Several other devicesare connected to the Ethernet net-work. One type is called a server.Servers are userless Altos that arededicated to some specific function.A server might be connected to aprinter. Thus, printing a file wouldactually consist of sending the propermessages to a Printing Server. Onecommon type of server is a FileServer. These machines supportextra-large disks and are repositoriesfor programs and files that are toolarge or too infrequently accessed tomake storage on individual machinesworthwhile. The Stanford File Serveris named Lassen.

Photo 8: The multiplayer Mazewargame. The eye represents the persona ofan opponent. Any Alto on the net canjoin or leave the game at any time.

Due to the design of the networkand the Altos, a new Alto can bewheeled in, plugged into the networkmedium (standard coaxial cable),and, with a blank disk pack freshfrom the factory, become entirelyfunctional with a full set of softwarein a matter of minutes. An Alto canalso be disconnected, moved toanother port in the coaxial cable, andreconnected without affecting eitherthe performance of the network orthe Alto.

Several programs exist that takeadvantage of the distributed process-ing capabilities inherent in theEthernet network. Of all of them, themost enjoyable are the games. Trek isa multiplayer "spacewar" game that iscontrolled primarily by the mouse(see photo 7). Mazewar is a multi-player romp through a realisticlabyrinth (see photo 8). The uniquefeature of these games is that largenumbers of users can join or leave thegame as they please without affectingthe play of the others. Since all theAltos can listen to the same packet(block information on the Ethernet)at once, the game program is neverrunning on any single coordinatingmachine. Instead, it is running in-

dependently on every participatingAlto.

The Future

A stand-alone Alto is usable, butthe best configuration is a group ofAltos connected by an Ethernetsystem. Since the Ethernet system is alocal network, a special device calleda gateway was developed to allowlocal Ethernet networks to speak toother Ethernet networks or packetnetworks of other types. Many com-panies are researching networkschemes that would allow packettransmission across cable-televisionlines. Since these cables are currentlyinstalled in many homes andbuildings, it is not difficult to imaginea city with an "information grid,"analogous to the electric-power gridthat exists today. Combined with anelectronic mail system (a prototypecalled Laurel is used on Altos today)the possibilities are staggering.

The Alto has been around forseveral years. As research tools go, itis covered with moss and gatheringdust. But new products will be ap-pearing on the market based on theexpertise gained in producing andusing the Alto. The next few yearsshould show a dramatic increase inthe quality of personal computingand the ability to interconnect per-sonal computers. And the Alto is oneof the first personal computers thatsatisfies the needs of the computerscientist as well as the secretary orbusinessman. ■

References

1. Lampson, B W and E Taft. Alto User'sHandbook. 1979.

2. Metcalfe, R M and D R Boggs. "Ethernet:Distributed Packet Switching For LocalComputer Networks." Communications ofthe ACM 19,7, July 1976, pages 395through 404.

3. Shoch, J F and J A Hupp. "Measured Per-formance of an Ethernet Local Network."Communications of the ACM 23,12,December 1980, pages 711 through 721.

4. Thacker, CP.EM McCreight, B W Lamp-son, R F Sproull, and D R Boggs. Alto: APersonal Computer. Tech Rep CSL-79-11.Palo Alto CA: Xerox Palo Alto ResearchCenter, August 1979. (To appear in Com-puter Structures: Readings and Examples,Second Edition. Siewiorek, Bell, andNewell, editors.)

68 September 1981 © BYTE Publications Inc

Customizable

The Unique Difference that SetsVEDIT Apart in Full Screen Editors

Total user customizability is a predominate reason thatover a thousand users find VEDIT the easiest to use full screeneditor. It makes VEDIT the only editing package which allowsyou to determine your own keyboard layout and use the cursorand special function keys on any terminal having them. Andonly VEDIT fully supports all of the newly available terminals. Itmay come as a surprise to you, that with any other editor or wordprocessor, you will have to memorize obscure controlcharacters or multi-character sequences, while your terminal'sextra keys and editing functions go unused. The customizationextends to setting the default tab positions, scrolling methodsand much more. It's almost like designing your own editor foryour system, applications and preferences. And all of this iseasily done with the setup program which requires noprogramming knowledge or 'patches', but simply prompts youto press a key or enter a parameter.

Unequaled Hardware Support

The CRT version supports all terminals by allowing you toselect during setup which terminal VEDIT will run on. Featuressuch as line insert and delete, reverse scroll, status line andreverse video are used on 'smart' terminals. All screen sizes aresupported, including large ones such as the 60 X 80 format onthe Ann Arbor Ambassador terminal. Special function keys onterminals such as the Heath HI9, Televideo 920C and IBM3101, and keyboards producing 8 bit codes are all supported.The memory mapped version is extremely flexible and supportsbank select and hardware cursors such as on the SSM VB3.With this level of customizability and hardware support, you willfeel for the first time that the software was optimally designed foryour system.

Fully Compatible Replacement for Ed

Since VEDIT creates and edits standard text files of up toone diskette in length, it serves as a replacement for the CP/M

standard editor ED. Of course, you benefit from the fastest andeasiest to use 'What you see is what you get' type full screenediting available, fast disk access and an editor which takes uponly 12K of your valuable memory space. With VEDIT you willnever again need or want to use the slow and tedious ED.

Special Features

VEDIT is more than just a full screen editing replacementfor ED, it gives you many new editing capabilities, such as ascratchpad buffer for moving and rearranging sections of text,complete file handling on multiple drives and iteration macros.Amoung its special features you will find automatic indenting foruse with structured programming languages such as Pascaland PL/1, and other special facilities for Assembler and COBOL.A real time saver is the ability to insert a specified line range ofanother file anywhere in the text. Unlike most software, VEDITwill even tolerate your mistakes. For example, one key will'Undo' the changes you mistakenly made to a screen line, andthe disk write error recovery lets you delete files or insert anotherdisk should you run out of disk space.

Ordering

Many dealers carry VEDIT, or you may contact us for fastdelivery. Specify the CRT version, your video board ormicrocomputer, the 8080, Z80 or 8086 code version, and diskformat required.

VEDIT for 8080 or Z80: Disk and manual $130

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IF YOU W\NT TO START\OUROWN COMPUTER OOMIANXWU NOW H^VE THE COMPUTER

TO START WITH

The entrepreneurial spirit runs rampantin the computer industry. In fact, it's come toour attention that a significant number of thetechnical/engineering types have some thoughtsof starting their own company.

So we have come out with a computerfor them. And for those entrepreneurs with-in companies who are in a hurry to get theirhot new project to market in a hurry.

It's called the MPT/100.

As you can see, the MPT/100 computeris small enough to fit in whatever corner youset aside for furthering your own ambitions.

And it'll cost you less than the price of abasic new car.

This computer is anything but basic.

Inside the MPT/100, you'll find a16-bit microNOVA™ computer. 64K bytesof memory 80 column by 24 line screen. Fullkeyboard with numeric pad. 716 KB of on-line storage on two 358 KB mini-diskettesall packaged in a system that has the kind ofsoftware, compatibility with more powerfulcomputers, ease-of-use and reliability that ^desk-top computers are noted for nothaving.

Also unlike most desk-topcomputer software, some verysophisticated (read easy-to-use)big computer software is avail-able for the MPT/100 com-puter: A multi-taskingFORTRAN that meets allthe ANSI standards.

A PASCAL that executes at assembly lan-guage speeds. An ANSI compatible BASKthat lets you write enormously complex pro-grams that take up only a little space. A

70 BYTE September 1981

full range of user-friendly interactive program-ming aids. And MP/OS, an operating systemanyone who's into operating systems will tellyou is one of the most advanced in the world.

(Anyone who considers any of the aboveto be of trivial importance should consider thefact that a single line of application code costsa good deal more than many microcomputers.And that cost is only going one way.)

Saving money on programming is onlypart of the attraction of the MPT/100. It alsosaves you time. So you can get your companyup and running before anyone can do thesame thing.

As you grow, all the softwareyou've written, all the peripherals

you've interfaced, all the blood, sweat andtears you've put into your company will growwith you. Because we've invested no smallamount of energy working to make our com-puters compatible.

The point here is that the MPT/100can make you what a lot of companies havebecome with Data General.

Like Aero Systems Engineering, of St.Paul, Minnesota, for example. They're farand above the leading manufacturer of com-puterized aircraft jet engine testing systems.A position they came to occupy partly bybuilding test facilities that could cut fuel con-sumption rates by 35%. Partly because ofour world-wide service. And partly becausethey didn't have to wait eighteen months toget our computers.

There is no stopping you from doingthe same thing.

If you want to get more detailed in-formation about the MPT/100 computer,call your local Data General office or yourData General manufacturer's representa-tive. Or the distributors listed below. Orwrite us at: MS C-228, 4400 ComputerDrive, Westboro, MA 01580.

MPT/100 computers are availablefor off the shelf delivery from:

SCHWEBER, HALL-MARK,KIERULFF, ALMAC/STROUM andR.A.E. in Canada.

Look at it this way.AH of you who want tostart your own computercompany, are very luckypeople. We didn't haveanybody to write towhen we got started.

IrDataGeneral

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microNOVA is a registered trademark of Data General Corporation. ©1981, Data General Corporation.

BYTE September 1981 71

Tree Searching

Part 1: Basic Techniques

Gregg Williams, Senior Editor

It is estimated that there are morepossible games of chess than there areatoms in the universe. This meansthat if a computer could generate onemillion chess moves a second, itwould take approximately 3.2 X 1060centuries to generate all possiblegames. How, then, can a $200microprocessor-based chess game(faced with analyzing a situation socomplex) play not only minimal butfair-to-good chess? Several tech-niques are necessary, but one of the

most powerful in the field of artificialintelligence is known as tree search-ing.

Tree searching allows a computerto determine the best of many alter-natives, while at the same timeevaluating as few partial solutions aspossible. Part 1 of this article dealswith the basic techniques of treesearching on three levels: theory, im-plementation (through several BASICprograms illustrating the majortechniques), and experimentation. It

PARENT NODE'

la)

SUCCESSOR NODES

(b)

Figure 1: Nomenclature of trees. Figure la gives the graphic representation of the statespace of a problem as a tree. Trees are characterized hy having only one start node (S),by containing only nodes that can be reached via the start node, and by having noarrows that lead to the same or lesser depth. Nodes n2U n32, and n27 are examples of ter-minal nodes; nodes n,2, nlit and n33 are examples of nonterminal nodes; nodes n31 andnlt (shown in color) are goal nodes. Note that a goal node can be either terminal ornonterminal. Figure lb shows the relationship between parent node n,3 and successornodes n26 and n21. Here, n,3 is said to be expanded to generate n26 and nI7.

will introduce basic terminology andsome well-known exhaustive treesearches (those that will eventuallygenerate all possible partialsolutions), as well as an illustrativeBASIC program (to solve the familiarsliding blocks "15-puzzle") that willbe used in both articles. The secondpart will deal with admissibleheuristic searches that use informa-tion about the system being searchedto cut down on the number of falseleads pursued; it will also covernonadmissible heuristic searches,which attempt to find a quicker solu-tion at the expense of losing the cer-tainty of a guaranteed optimal solu-tion, or of finding a solution at all.

Basic Terminology

The purpose of artificial in-telligence, according to one school ofthought, is to produce computer pro-grams that will solve problems noteasily solved by computers—prob-lems that can be solved by an "in-telligent" agent (usually a human).The solution to many of these prob-lems can be seen as the attempt to ar-rive at a solution (or goal) whoseproperties are unambiguously de-fined, from an initial state (or node),according to some specific set ofrules. Between the starting node andthe goal node are other nodes thatrepresent intermediate positions. We

72 September 1981 © BYTE PublkaHora Inc

-Peachtree Software Eliminates The-

PEDUNCLE

It certainly is nice to know those beautifulspring blossoms on flowering peach trees aresessile blooms. Sessile, according to Webster,simply means the flowers arenot raised upon a peduncle.Well, thank goodness for that!And Webster adds that apeduncle is the stalk that sup-ports the fructification in

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ou're really going to ap-preciate the "self teaching"simplicity of Peachtree Software'sdocumentation. You'll be onyour own in no time, with noneed for "support." Our learn-by-doing manual shows youexactly what will appear on thescreen. Menu driven, our pro-grams prompt you at every pointwith the selections available.There's sample data for self-training and practice, too. Sogoodbye forever to peduncles . . .who needs 'em!

Wide variety of packages, allfrom the same tree. Here's just asample.

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some thallophytes. Big deal. . . . We atPeachtree Software are very pleased to assureyou that due to our advanced technology, ourthallophytes fructificate with-out the need of any supportwhatsoever! Software dealers,rejoice ... your peduncle wor-ries are over forever. Isn'tmodern science wonderful?

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BYTE September 1981 73

are interested in the particular se-quence of nodes that makes up theshortest path to one of several possi-ble goal nodes. Many nodes (usuallyan overwhelming number) do not lieon the optimum path, and the pur-pose of tree-searching methods is toexplore as few of these as possible.

A number of problems that do notseem to lend themselves to treesearches can be made to do so whendescribed in a finite-state representa-tion. Sometimes, in the case of prob-lems that have a continuous (andtherefore infinite) range of variation,this means quantizing the probleminto a finite number of discrete steps:an example is considering the range oftemperatures of 20° to 30 °C as a setof discrete temperatures—say, 20.0°,20.1°, 20.2°, ... 29.9°, and 30.0°.Theoretically, this results in some lossof accuracy, but most problems canbe quantized in sufficiently small in-crements that accuracy is not a prob-lem.

A finite-state representation con-sists of the following: a start node, awell-defined node or set of goalnodes, and a set of rules or operatorsthat allows the user to generate allpermissible successor nodes from agiven node. In some cases, the pathfrom a node to its successor node(that is, one generated by the single

Figure 2: A directed graph. This figure,which represents the structure of many"real-world" problems, differs from a treein that successors may be in the same or a"shallower" depth (note colored arrows).The successor of n33 is n12; the successorof n17 is n,3. Tree-searching algorithmscan be modified to handle graphs, but thisarticle will deal exclusively with trees.

application of an operator to theparent node) may have a costassociated with it, with the cost of agoal node being the total cost in-curred along the shortest path fromthe start node to the goal node. Theset of all nodes that can be derivedfrom the start node is called the statespace.

A tree is one possible representa-tion of the state space of a problem.As shown in figure 1, nodes arerepresented as points, and the rela-tionship between a given node and itssuccessor is shown by a directedarrow that points from the parentnode to the successor node. We willlabel the start node S, and each of theother nodes' according to its rank

(distance from the start node) andlateral position within the set of allnodes with the same rank (this is anarbitrary labeling, but it is orderlyand useful). Referring to figure la,nodes n„, nX2, and n13 are all thenodes of rank one. Node n12 has twosuccessor nodes, n24 and n25. Node n4Jis the only node of rank four.

Some nodes do not yield any newstates upon application of theoperators that define the transitionfrom one state (node) to the next.These are called terminal nodes; ex-amples in figure la are nodes n21, n22,n23, n25, n27, n31, n32, and n41. Nodesmarked G are regarded as goal nodes;they can be either terminal or nonter-minal nodes.

(a)

s = ®

ABDCj) GOALCOST=18

(b)

Figure 3: The traveling-salesman problem. Given the map in figure 3a, the objective isto find the shortest route from city A through cities B, C, and D. The tree of figure 3bgives the finite-state representation of the problem, with each node being a partial trip(eg: ADC is the trip from A through D and C) that has a cost dependent upon the routetaken. Here the problem is discrete, and any node has only a finite number of suc-cessors; at node AD, only two "next moves" are possible: ADB and ADC. The shortestroute is shown in color.

74 September 1981 © BYTE Publications Inc

"Together we're workingto better serve mankind!'

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Often the state space of a problemwill allow a node to generate as suc-cessor a node of equal or lesser rank,as shown in figure 2. In this case, theresulting representation is called agraph (or, more completely, adirected graph). This will call for onlya slight addition to the searchstrategy, but the difference should benoted.

Finally, as mentioned before, atransition from a node to its successormay have a cost associated with it. Ifso, the arrow connecting the two willbe labeled with the cost; otherwise,the arrows are unlabeled and each isassumed to carry a unit cost.

Some Examples

First we will examine a discreteexample: the traveling salesmanproblem. A traveling salesman in cityA must travel to cities B, C, and D, inany order. Given the map in figure3a, what order of cities gives theshortest total mileage?

In this problem, the nodes are par-tially completed (or completed) tripsdescribed by a sequence of the lettersA, B, C, and D, restricted by the rules

that follow. The start node is A(salesman in city A, no travelingdone). Four goal nodes describevarious routes, ABCD, ABDC,ADBC, ADCB. The rules are infor-mally described: from a given node,add the letter of any city that con-nects to the last city visited and thathas not yet been visited.

Since the number of cities is small,a full state-space tree is possible(figure 3b), and it is clear that theshortest route is ADBC, with adistance (cost) of thirteen. But what ifthere are ten cities? Twenty? What ifsome roads are one-way?

Next we see a continuous example(here the state space must be cut intoa finite number of discrete values).You have a faucet, a sink, and anempty glass with a horizontal line onit: fill the glass up to the line.

First we must quantize the prob-lem. Suppose we say that the glassholds 100 ml of water. We canreasonably set the smallest unit ofwater to be manipulated at onemilliliter. The state of the problem isthe amount of water in the glass, andthe problem has 101 possible states: 0

ADD 100 ml.

76 September 1981 © BYTE Publications Inc

Figure 4: The "quantization" of a continuous-solution space. Shown is a partial tree forthe problem of filling a water glass to a specified mark. It is continuous in that the prob-lem space (the amount of water in the glass) can hold an infinite variety of states(amounts of water). By considering the glass to hold water only in single-milliliterincrements, the problem space becomes discrete and finite, and thus can be representedto a computer. Goal nodes exist where the water level matches the mark on the glass.

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ml (empty), 1 ml of water, 2 ml, . . .,100 ml. (Here the word "state" seemsmore natural than "node"; the latterusually refers to the graphic represen-tation of the problem.)

Time as well as volume must alsobe quantized, which restricts us toadding or subtracting a given volumeof water "at one time." We have 200possible operators (some of whichmay be physically impossible for agiven state): add 1 ml, pour out 1 ml,add 2 ml, . . . and so on up to add orpour out 100 ml. Finally, the goalnode is any set of actions that bringsthe water level up to the marked line(wherever it happens to be). Thestate-space tree is large but finite; partof it is shown in figure 4.

The 15-Puzzle

Most of us have played with the15-puzzle: fifteen numbered squares

that slide around in a frame thatallows four units on a side. Theblocks are given in an arbitrary orderand the object is to slide the blocksuntil, read by row, they are in as-cending order with the blank space inthe lower right-hand corner. (Math-ematician/puzzlist Sam Lloyd made alot of money betting people theycouldn't solve the puzzle. It was asure bet; with the starting position heused, a solution was impossible.)

We will use the 15-puzzle to illus-trate various search methods. TheBASIC program SEARCH (see listing1) will implement different searchtechniques by changing only onesubroutine. It will work for both the15-puzzle and (for computers withless memory) the order-3 variation:the 8-puzzle. In this article we will usethe 8-puzzle for illustration; evenText continued on page 86

^0PEN= *\

(START NODEy

exttwithXfailure j

PUT A (NODE AT TOPOF OPEN LIST) ONTOCLOSED LIST

EXPAND A FOR SUCCESSORNODES, GIVINGS(i):(S(l),S(2) S(N)|

TRACE POINTERSBACK, GIVING SOLUTION

MERGE S(i)'s ONTOOPEN LIST

(EXIT WIThASUCCESS J

Figure 5: The basic flowchart used to derive the SEARCH program of listing la. Thisflowchart is a modernized, generalized version of several given by Nils Nilsson inProblem-Solving Methods in Artificial Intelligence. The flowchart was written as struc-tured pseudocode (see listing lb) before becoming the BASIC program SEARCH.

78 September 1981 © BYTE Publications Inc

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Business Programmers: Take the COBOLexpertise you have acquired on big businessmainframes, and use it on Apple II to create friendlyapplications that will talk directly to your users -where it suits them best, on their own desks.

CIS COBOL's dynamic module loading givesyou big application capability and the FORMS-2source generator lets you build and modifyconversational programs from visual screenformats, creating much of the code automatically.

Application vendors: CIS COBOL withFORMS-2 steps up the pace for your developmentof the high quality professional applicationpackages needed today. And creating them inCOBOL makes them more maintainaPle.

Over half the Apple II's now being sold are goingto business or professional users so demand forquality applications is growing fast, creating bigbusiness opportunities for you.

Stability proven by the US Government.

CIS COBOL has been tested and approved for twoconsecutive years by the US General ServicesAdministration as conforming to the ANSI 74COBOL Standard. Apple II under CP/M is includedin CIS COBOL's 1981 GSA Certificate of Validation(at Low-Intermediate Federal Standard plusIndexed l-O and Level 2 Inter-ProgramCommunication).

Get your hands on CIS COBOL at yourApple dealer.

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Micro Focus Inc., 1601 Civic Center DriveSanta Clara, CA 95050. Phone: (408) 248-3982.

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CIS COBOL with FORMS-2 for use on the Apple II with CP/M is an Apple Distributed Product.CIS COBOL and FORMS-2 are trademarks of Micro Focus. CP/M is a trademark of DigitalResearch. Apple II Is a trademark of Apple Computer.

Circle 221 on inquiry card.

BYTE September 1981 79

Circle 125 on inquiry card.

Toughest Boardsin Town...IEEE 696/S-100

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IEEE696/S-100 A1M-12 industrialstandard module designed forindustrial analog-to-digital use.

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Listing 1: The SEARCH program, written in Applesoft BASIC for the Apple II. Listingla gives the program as implemented in BASIC. Listing2, 3, or 4 must be added for thisprogram to work. The subroutine that starts at line 9900 implements a given searchmethod; all REM (remark) lines can be deleted to reduce program size. The diagnosticmessage printed by line 177 gives visual feedback on the progress of the program,although it does not give the correct value for the start node (node 1). The structuredpseudocode in listing lb outlines the processes in SEARCH. Line numbers here refer tothe "main line" of the program.

i REM —SEARCH ALGORITHMS AND PGM FUR tS PUZZLE

2 REM —SRESG WILLIAMS, BYTE MAGAZINE, POB 132, HANCOCK NH 034195 REM

■I REM

3 REM LIST INS 1

100 DIM ni'L00).01 LOO),R*<20)

I 02 0 1 l-i A* (4) , E* (4, 4) , I-1 ■ 'I, -i > , Z ' 1 6>

I 10 REM — INI I I ML I U PROGRAM

120 B0SUB 9500

I 25 REM

I 30 Rl M

L3S REM --NEXT IS DO-WHILE LOOPsWHILE"0PEN" ARRAY NOT EMPTY AND EXIT

I 40 REM —VARIABLE""SEARCH"

LS0 II El» -: "EX II " MIEN 495

158 Rl 11

] 60 REM

165 REM —FIND N1=INDEX 0E LOWEST OPEN VALUE

!'0 60SUB 9000

175 IF OlNII = 99999 THEN 4 95

177 PRINT "177-EXPAND NODE "sNl;", ";0*(N1>;'\ VAL-"s0(Nl>

1 BO REM

185 REM —RUT NODE TO CLOSED!"SCRATCH" IN OPEN ARRAY

J137 REM — BY GIVING LARGE VALUE

190 C9 = C9 > I

200 0(N1) » 90000 + 0(N1)

220 REM

225 REM

230 REM —UNPACK BOARD POSN AMD GENERATE SUCCESSORS IN As

240 E* ■ MID* (0*INI),HI + 1,L2)

250 E9* = M T Dt (0* CN1),H I. , 1 )

255 BOSUB 9100

260 REM —NODE tt Nl IS PASSED AS ITSELF

265 REM —GENERATE SUCCESSORS

270 BOSUB 9200

275 REM

280 REM

285 REM —EVALUATE EACH FOR GOAL STATUS—Gl NODES WERE GENERATED

2B7 IF Bl > 0 THEN 295

290 PRINT "290—MO SUCCESSORS, N0DE";N1

292 (SOTO 470

295 G* = "NOT GOAL": FOR Ml = 1 TO Bl

300 REM —RETURN "GOAL" IF A*(Ml) IS GOAL NODE

310 BOSUB 9600

320 IF S* < > "GOAL" THEN 3130

330 El* = "EXIT"

340 REM —SAVE INDEX OF GOAL NODE

360 REM —FOLLOWING IS "ELSE" BRANCH OF 320:G* NOT = "GOAL"

370 REM —UNPACK BOARD TO E*,F* ARRAYS

380 E* = MID* (A*(Ml),HI + 1,L2)

390 BOSUB 9100

395 REM —EVAL H-HAT FCN FDR E*. RESULT IN Rl

400 BOSUB 99O0

410 REM —PUT A* (Ml) ON "OPEN" LIST

420 09 =09+1

430 0*(09> = A*(Ml)

440 0(09) - Rl

450 NEXT Ml

460 REM —END OF DO-WHILE LOOP AT 150

4 70 BOTO 150475 REM

480 REM

485 REM —THIS SECTION PRINTS EITHER SOLUTION OR FAILURE MESSAGE

495 IF GS < > "GOAL" THEN 540

500 REM --TRACE BACK SOLUTION

510 BOSUB 9800

520 60T0 550

530 REM —NO SOLUTION FOUND

540 PRINT : PRINT "NO SOLUTION FOUND"

550 PRINT "NODES ON OPEN LIST: ":09 - C9

560 PRINT "NODES ON CLOSED LIST:";C9

570 END

8000 FOR I = 1 TO R9

8010 FOR J m 1 TO R9

B020 PRINT F*(I,J);: NEXT J

B030 PRINT " ": NEXT I

8040 RETURN

8890 REM

BB95 REM —SUBRTN TO CHECK IF NEW BOARD F* ( I , J >

Listing la continued on page 82

80 September 1981 © BYTE Publications Inc

Circle 108 on inquiry card.

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Listing la continued:

B900 Q3$ = "NOT DUPLICATED"

8905 REM —CHECK. THROUGH ALL. EXPANDED NODES

8910 REM — I.E., NODES WITH D(I)>=90000

S915 FOR I = 1 TO 09: IF 0(1) < 90000 THEN B930

8920 Fl» » MID* (Q*(I),H1 + 1,L2)

8925 IF F* = F.l* THEN S3* « "DUPLICATED" THEN B938

8930 NEXT I

8935 IF (33* = "NOT DUPLICATED" THEN 8938

13937 PRINT "8937—CURRENT POSN IS DUPLICATE ***"

8938 RETURN

B985 REM

8990 REM —SUBRTN TO FIND Nl SO THAT 0<N1> IS SMALLEST

8995 REM

9000 SI = 99999:Nl = 1

9005 FOR I = 1 TO 09

9010 IF 0(1) > = SI THEN 9020

9015 SI = 0(1):N1 = I

9020 NEXT I

9025 RETURN

9035 REM

9040 REM --PACK BOARD F*(N,N) TO STRING F*

9045 REM

7050 F* = ""

9055 FOR B = 1 TO R9

9060 FOR D = 1 TO R9

9065 F* = F* + F*(B,D)

9070 NEXT D

9071 NEXT B

9090 REM

9095 REM —UNPACK STRING E* INTO ARRAYS E*(N,N), F*(N.,N!

9100 FOR I = 1 TO R9

9105 FOR J = 1 TO R9

9110 G1 = R9 * (I - 1! + J

9115 E*U,J) = MID* <E*,01,1)

9120 F*(I,J) ■ MID* (E*,Q1,1)

9125 NEXT J: NEXT I

9 1 -ii RETURN

9)90 REM EXPAND CURRENT POSN IE* ( I , 3 ) WITH DIRECTION E9S,NQDEtt Nl

9(95 REM — BIVINS SUCCESSORS IN ARRAY A*(N>iN=l TO SI

9200 FOR I - 1. TO 5

9205 IF E9* = MID* <D*,I,1) THEN 9210

9207 NEXT I

9210 09* ■ MID* (I*,I,1)

9215 REM Q9* IS FORBIDDEN DIRECTION TO EXPAND E*

9220 FOR Yl « 1 TO R9: FOR X] = 1 TO R99225 IF E*(.«1,Y1) = "„" THEM 923139230 NEXT XI: NEXT Yl

9235 REM X],Yl "COORDINATE OF "BLANK" IN PUZZLE

9238 Gl = 0

9240 REM —NEXT IS A LOOP THAT GENERATES 4 POSSIBLE SUCCESSORS

9242 SI = 1:A9 = 0

9245 IF SI > 4 THEN 9315

9250 IF MID* (D*,S1,1) = 09* THEM 9.310

92S5 X2 * XI + X(S:l):Y2 = Yl + Y(S1)

9260 FOR I = 1 TO R9s FOR J = 1 TO R9

9265 F*< .(,,!> = ES(I,,1); NEXT J: NEXT I

9270 REM —EXCHANGE SQUARES (XI.Yl) AND !X2,Y2)

9272 IF X2 < 1 OR X2 > R9 THEN 9310

9273 IF Y2 < 1 OR Y2 > R9 THEN 93109275 F*(X1,Y1) = F*(X2,Y2):F*(X2,Y2> =9280 REM —PACK NEW BOARD AS NODE IN A*(N)9285 GOSUB 9030

92B7 REM —CHECK FOR DUPLICATES IN 0*9290 BDSUB S900

9295 IF 03* = "DUPLICATE" THEN 9310

9296 REM —NQDE=POINTER BACK-i-DIRECTION+PACKED ARRAY

9297 A9 « A9 + 1

9302 GOSUB 9400

9303 A*(A9) = 0* + MID* <D*,S1,1) + F*9305 Gl = Gl + 1

9310 St ■ SI + is GOTO 924 59315 RETURN

9390 REM

9395 REM --8UBR CONVERTS Nl TO A STRING OF CHARS, LENGTH OUTPUT IN 0*

9397 REM

9100 Q* = STR* (Nl)

94 10 CM m LEN (Q*)

9420 REM —ADD LEADING ZEROES TO 0*

9425 02 = 08 - Ql

9430 IF 132 > = 0 THEN 9440

9435 PRINT "SIZE ERROR IN 9400—ABORT JOB": END

9440 IF (32 == 0 THEN 9455

9445 FOR I = 1 TO 02

9450 P* = "0" + Q»i NEXT I

9455 RETURN

9485 REM

9490 REM —SUBRTN TO INITIALIZE PGM

9495 REM

9500 08 = 3:R9 = 3

9505 DATA -1,0,0,1,1,0,0,-1

9510 FOR I = 1 TO 4: READ X(I),Y!I): NEXT I

95:15 D* = "DLURB":!* = "URDL"

9520 E9* = "B"

9523 02* = "1.3426758": GOTO 9535

9S25 PRINT : PRINT "ENTER PUZZLE TO BE SOLVED IN "jR9 * R9;" CHARACTERS"

Listing la continued on page 84

82 September 1981 © BYTE Publications Inc

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Listing la continued

953095359540954595509552955395559560956595759580958595879590959)95959600961096159620962596309635968597859790

9B10

98179820

9825

INPUT 02*

IF LEN <Q2*> = R9 * R9

PRINT : PRINT "ERROR IN

GOTO 9525(.19 = 1:0(1) = 0Nl = Is GOSUB 9400Q*(l) " 0* + "B" + 02*

REM — ABOVE IB INITIAL

THEN 9550PUZZLE ENTRY

- TRY AGAIN.'

.>; '

"84M984598 ,(

9855

(lb)120

150170190270

287295310320330

400420

450

470

495510

540

IZATIQN OF "OPEN"

LISTS, ARRAYS' LISTS—C AND

BOARD IS" OR "NOT

GOALGOAL'

NODE

hEM --- NEXT 18 INITIALIZATION OF "CLOSEDC9 « 0

HI = OB ■!■ 1 ;L2 R9 * R9

El* * "SEARCH"B* = "NO GOAL"

RETURN

REM —BUBRTN TO SEE IF

REM -—RETURNS G*="S0AL03* = "1.2345678. "

IF R9 = 4 THEN (33* = " 123456789ABCDEF. "Q4* = RIGHT* <A*(M1>,L2)

IF 03* ■ Q4* THEN 8* = "GOAL. ":N6 = 09 + ')

REM —N6=IN0EX OF GOAL NODE;=09+1 BECAUSE 09 POINTS TO LAST

REI'I — NODE FILLED; SEE 420-440

RE I URN

REM

REM

REM

O AND O*

C* ARE BOTH EMPTY

■-8UBRTM TO TRACE BACK AND PRINT SOUM FROM 0*<N1)

R

"B1, 1)

REM —DO UNTIL POINTER0* « MID* (0*<N6),OB +

IF Q* » "B" THEN 9820Ri = Pi + I :R*(RI ) = (5*PIS = LEFT* (0*(N6),0B)N6 VAL (01*)

"B" THEN 9310

DQNI ) PRINT VALUES OF R*

= 0 THEN PRINT : PRINT

NT "SOLUT [ON IS " ;

STEP - 1

I r 0*REM —IF RIPRINT :

FOR M ■PR INI "NEX'I N

PR[Ml r

II R I■■I. I::p| rURN

FROM :■•) TO 1

"ZERO ERROR IN BACKTRACKING"

GO 10 988'.'

PR!

PI 10 1

";!<•!. '. N I j

PRINT ;

I rHEN

r- R 11' i

PR I I'MPR I N'l

EXIT = no, GOAL = no part of initialization routineOPEN =< start node >

do while OPEN not empty and EXIT = no:A = top node in OPEN:put A from OPEN to CLOSED list:expand A giving successors A(N)

if successors exist

for each successor

:evaluate successor for goal status:if node-is-goal

: :set G = index of good node, GOAL =: :set EXIT = yeselse: : calculate "value" of node: : :merge node and value into OPEN list: end if

: :end of for-loop

:end ifendwhile

if GOAL = yes

:find solution by tracing nodes back from G

:print full solutionelse

:print failure messageendif

Yes

570 end program

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Circle 375 on inquiry card.

Text continued from page 78:

with this 3-by-3 puzzle, the search

tree grows rapidly.

Elementary Strategy

A certain form can be used to im-plement any search strategy. Itassumes the following: two listscalled OPEN and CLOSED, theformer for nodes that have not beenexpanded (ie: that have not had allpossible successors generated) and thelatter for nodes that have been ex-panded; an algorithm for generatingall legal successors; and an algorithmfor determining whether or not anode is a goal node. One final

algorithm, /, which implements thegiven search technique, provides afunction that is used to order themembers of the OPEN list to deter-mine which node is to be expandednext.

The general algorithm is given inflowchart form in figure 5. It may bedescribed as follows:

1. Place the start node on OPEN.CLOSED is empty.

2. If OPEN is empty, no solutionexists; exit with failure.

3. Otherwise, let A equal the node atthe top of the OPEN list. Take A offthe OPEN list and put it on theCLOSED list.

4. Find all possible successors of A,named S(l), S(2),...S(N).

5. If there are no successors (N=0),go to 2.

6. Check the successors for goalstatus. If one is a goal, go to 8.

7. Calculate the /-values of each suc-cessor and merge the nodes into theOPEN list so that the OPEN nodesare sorted in ascending /-values.Also, place a pointer in each suc-cessor node that points back to theparent node A. Go to 2.

8. Trace the goal node through thepointers to the start node. Thissequence, reversed, is the solution.

9. Exit with success.

The method described above is ex-haustive and complete—that is, italways terminates. If it returns withan "exit with failure," it is because allnonterminal nodes have been ex-panded without finding a goal.

Circle 377 on Inquiry card. —+■

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Overview of the SEARCH

A complete explanation of theSEARCH program would be unreas-onably long, so I am including onlythose points that will save the readerfrom puzzling through the mechanics.All comments refer to the 15-puzzleversion. (Conversion to the smaller8-puzzle is achieved by changing thevalue of R9 to 3 in statement 9500 oflisting 1.)

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• The program in listing laequivalent to the structured pseudo-code of listing lb and the flowchart offigure 5.

• The major variables used in the pro-gram are given in table 1.

• The body of the SEARCH program(which corresponds to the pseudo-code algorithm) is contained in lines120 through 570; the subroutines usedare listed in table 2.

• Instead of new nodes being sorted

into the OPEN list, they are added atthe end of the list and given an order-ing value. Instead of expanding thetop node on the list, the node with thelowest ordering value (in array O(N)) is expanded. This eliminates anunnecessary sort in the program.•The program has eliminated theneed for a CLOSED array by taggingnodes to be closed with an O-value ofgreater than 90,000. The number ofnodes that has been closed is in C9.

• The SEARCH program assignsvariable names to certain constantswithin the program so that the pro-gram can be altered to fit computersof different sizes by changing only afew statements. See variables L2, 08,and R9 in table 1.

• The complete representation of anode in this program includesvariables O(N) and 0$(N), where Nis the number of the nodes. O(N) isthe orderings value relative to the

VariableName Use

A$(N) Array of successors generated by current board position E$(I,J); see A9.F$(N) String of characters equivalent to board F$(I,J); see subroutine at line 9050.O(N) Ordering value of node N on OPEN list; node is considered to be on CLOSED

list if O(N) > 90,000.0$(N) Body of node N on OPEN list; see text.R$(N) Letters that, when arranged in reverse order, give the solution to the puzzle;

see R1.X(N),Y(N) Increments in x- and y-position to cause a unit move in direction N,

N = 1,2,3,4.E$(I,J) Representation of current node in expanded form; I, J vary from 1 to R9.F$(I,J) Scratch pad board used to generate successors to board E$(I,J).A9 Number of nonduplicate successors generated; see A $(N).

C9 Number of nodes that have been tagged as closed, see O(N).

D$ The characters of D$ represent the possible moves in the puzzle (down, left,

up, right) and their orderings (eg: move 2 = MID$(D$,2) = "L" = left; move

5, B, stands for "beginning" and applies only to the start node).E9$ Direction used to get to current node from its predecessor.

G$ Indicates whether or not A$(MI) is a goal node.

G1 Number of successors generated before check for duplicate nodes.

H1 (Index of first character of game in 0$(N)) minus 1; used to index the L9

characters of the board.L2 Number of characters in current board; =9 for order-3 board, =16 for

order-4 board.N1 Index of O(N) giving smallest ordering value; node N1 will be expanded next.

07 Maximum size of arrays O(N), 0$(N).

08 Number of digits in 0$(N) pointer to its predecessor; set to 3, but, by expand-ing, can be used to process larger search.

09 Number of nodes (both open and closed) on 0$(N) list; next new node will beplaced inO$(09 + 1).

09$ Direction that backtracks from current node to predecessor; see text.

R1 Number of steps to solution of puzzle; see R$(N). Also, value returned by

subroutine at 9900.R9 Rank of problem; set to 3 for order-3 board, to 4 for order-4 board.

S1 Current smallest ordering value of array O(N), S1 = 0(N1).

Table 1: Major variables used in the BASIC program SEARCH (see listing 1),

88 September 1981 © BYTE Publications Inc

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other nodes; 0$(N) contains threethings: the direction (U, D, R, or L)that transforms the predecessor of0$(N) to 0$(N), an 08-digit pointergiving the node number of 0$(N)'spredecessor node, and a string of L2characters that describes the "board"of node N in compressed form. (Seefigure 6 for further details.)• For any node not the start node, it isalways possible to eliminate one ofthe legal "next moves." For example,if O(Nl) generates 0(N2) with amove of D (down), we can forgetabout generating the successor of0(N2) that uses the move U (up),because the result will be the sameboard as in node Nl (which hasalready been expanded). In theSEARCH program, this is done bymatching the "direction" of the cur-rent node in D$ with its correspond-

ing letter in 1$ (1$ is a mnemonic for"inverse"); this second letter is thenignored in expanding the currentnode (see the subroutine of 9200).

• It is possible for a series of moves tocome back to a previously expandednode (this means that the state spacefor the 15-puzzle is a graph, not atree). For this reason, the possiblesuccessors generated in lines 9240through 9310 (subroutine 9200) arechecked for duplication (subroutine8900, used at line 9290).

• Each of the four possible moves inthe 15-puzzle is associated with anumber between one and four (1means the tile moves down, 2 in-dicates the tile moves to the left, 3means the tile moves up, 4 means thetile moves right). Variables that usethis numbering are X(N), Y(N), D$,and 1$.

• Within the character representationboard, the position with no tile is rep-resented by a period.

• The SEARCH program was run onan Apple II with 48 K bytes ofmemory, and it should run withoutmodification on the CommodorePET, the Radio Shack TRS-80 ModelI Level II or Model III, or any othercomputer that uses Microsoft BASIC.The program is written so that allREM lines can be deleted without af-fecting the program's performance.

Exhaustive Tree Searching

The first method of systematicallysearching a tree can be described asfollows: expand the start node,recording all the successor nodes(which are of depth one); if none ofthe nodes are goal nodes, expand alldepth-one nodes, giving depth-two

(6b)

0(10) = 50(23) = 3

O$(10) = "L 001 12345.786'0$(23) = "U 010 12345678.'

Figure 6: Representation of the 8-puzzlewithin the program SEARCH. A node isrepresented in the program as twovariables. One is O(N), the ordering valueof node N in the tree. The other is 0$(N),a string that has the following:

• the direction used to get from N's parentnode to N

• the node-number of N's parent node(linking N back to the start node)

• the board position for node N, writtenby rows

Figure 6a shows part of a hypotheticaltree; figure 6b shows how nodes 10 and 23are represented within the program.

Entry

Point

Use

8900

Input:

Board F$(I,J), array 0$(N)

Process:

Determine if board F$(I,J) has already been expanded.

Output:

Q3$ = "DUPLICATED" or "NOT DUPLICATED."

9000

Input:

Array 0$(N), 09

Process:

Find smallest value in array.

Output:

Index N1, value S1 such that S1 = 0(N1) is smallest value in O(N).

9050

Input:

Board F$(I,J)

Process:

Compress to a row-major string of characters.

Output:

F$ = String of L2 characters.

9100

Input:

String E$

Process:

Unpack string to board E$(I,J), F$(I,J).

Output:

Identical boards E$(I,J), F$(I,J).

9200

Input:

Board E$(I,J), node number N1, direction E9$.

Process:

Generate up to three legal successors of board (which is derivedfrom node N1), eliminate nodes already expanded, build full node(direction + pointer + board) for each successor.

Output:

Table of successors A$(N), A9.

9400

Input:

Number N1, desired length 08.

Process:

Convert N1 to a string; strip off the leading blank, fill with leadingzeroes.

Output:

String Q$ that "looks like" ISI1.

9500

Initialization routine; includes entry of puzzle to be solved.

9600

Input:

Node A$(M1), rank of problem R9.

Process:

Extract compressed board from node, compare to goal node

Output:

G$ = "GOAL" or "NOT GOAL".

9800

Input:

Goal nodeO$(N1).

Process:

Trace through pointers back to start node, collecting "directionletters" in R$(N).

Output:

Print (R$(R1), R$(R1 - 1), ..., R$(1)) - solution to puzzle.

9900

Input:

Node 0$(M1) to be added to list, list O(N) (and other variablesdepending on method).

Process:

Adjustment of values in O(N); computation of ordering value fornode M1, placed in R1, so that node M1 will be correctly insertedinto OPEN list with a correct ordering value.

Output:

This is the subroutine implementing a given search algorithm.

Table 2: A

description of the subroutines used in SEARCH.

90 September 1981 © BYTE Publications Inc

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nodes; repeat this process until a goalnode is found or until no unexpandedsuccessor nodes can be found.

In terms of the overall algorithmfor tree searching (see figure 5), weimplement this breadth-first algo-rithm by putting the newly generatedsuccessors on the top of the OPENlist—or, equivalently, by giving thesenodes an O(N) value equal to theirdepth. Figure 7a shows the order inwhich nodes are expanded in abreadth-first search; note that all thenodes of depth n are expanded beforeany node of depth (ti + 1) is ex-panded. The subroutine to implementthe breadth-first algorithm is given inlisting 2a; its structured pseudocode

(7a)

equivalent is:

9900 value of node returned,Rl = value of parent

O(Nl) + 1

In a breadth-first search, makingthe "value" of any node equal to itsdepth will cause all nodes of level n tobe expanded before any node on leveln + 1 (with "value" n + 1). In line9900, the value 90000 is subtractedbecause, by this time, the parent nodeO(Nl) has been "marked" as beingclosed by adding 90000 to it.

An alternate approach to treesearching is the depth-first algorithm.In this method, we repetitively ex-

18 4

(7b)

(7c)

Figure 7: Order of expansion by three exhaustive-search algorithms. The numbers tothe right of each node show the order in which the tree is expanded. Figure 7a, thebreadth-first search, is examined laterally, one level at a time; figure 7b, the depth-firstsearch, takes a "walk" around the edges of the tree (as shown by the colored arrows);figure 7c, the limited depth-first search, combines properties of both types of search.These searches can be tried by installing the routines in listings 2,3, or 4 in the SEARCHprogram (listing 1).

92 September 1981 © BYTE Publications Inc

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pand the successors of a given node(until no such node can be further ex-panded) before we start to expand thenext node of the same depth; that is,we expand down the tree instead ofacross it, and are, in essence,generating and expanding the ter-minal nodes from left to right. Figure7b shows the order in which treenodes are expanded in a depth-first

search; the subroutine to be insertedinto SEARCH is given in listing 3. Itspseudocode equivalent is:

9900 value of node returnedRl = value of parent

O(Nl) - 1

In a pure depth-first search, thenode just generated should be ex-

Listing 2: Subroutine to implement a breadth-first search strategy.

10 REM LISTING 2

9B90 REM — SUBRTN TO COMPUTE H-HAT; BREADTH-FIRST SEARCH9895 REM — RESULT R1=VALUE OF PARENT+19900 Rl --= <0(N1) +1) - 90000990S RETURN

Listing 3: Subroutine to implement a pure depth-first search strategy.

9890 REM LISTING 3

9895 REM —■ SUBRTN 10 COMPUTE H-HAT; PURE DEPTH-FIRST (SEARCH9900 Rl = (D(N1) - 90000) - 19905 RET URN

Listing 4: Subroutine to implement a limited depth-first search strategy.

9885 REM - LISTING 4

91390 REM — SUBRTN TO COMPUTE H-HAT BY LIMITED DEPTH-FIRST SEARCH

9895 REM — VALUE RETD=R:U LIMIT OF DEPTH=R3

9900 R3 = 3

9905 Rl = (0(M1) - 90000) - 1

99.10 IF Rl = - R3 THEN Rl =0

9915 RETURN

panded before any other nodealready on the OPEN list from pastexpansions. A good solution is to letthe "value" of the successor node beone less than that of the parent. Sincethe subroutine at 9900 chooses thenode with the smallest O array value,this scheme forces the order of expan-sion just described.

Putting the depth-first algorithm towork, we find that it seeminglygenerates nodes without end—butwithout making a practical attempt atmoving toward a goal node (exceptwhen one happens to be on the left-most side of the tree). The handicapof the depth-first algorithm is that itwill search to the end of a givenbranch before returning to shallowerlevels. Because most trees extend to alarge, if not an unbounded, depth(whereas a goal node usually exists ata shallower level), the depth-firstsearch is usually inferior to thebreadth-first search: the formersweeps up and down the entire lengthof the tree from left to right, whereasthe latter scans uniformly across eachlevel of the tree from top to bottom,

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usually first encountering a goal nodeat a shallow level.

The limited depth-first algorithm(see figure 7c and listing 4) can be ex-plained as follows. Choose an ar-bitrary depth, n; do a depth-firstsearch, rejecting (for the moment) allnodes of depth n or greater. If thisdoes not turn up a goal node, do adepth-first search of the previouslyrejected nodes, rejecting all nodes ofdepth 2n or greater. Repeat this pro-cess until a goal node is found or thetree is exhausted. This is summarizedin the pseudocode:

9900 R3 = depth of each "layer" of

search9905 value of node returned,

Rl = value of parent

O(Nl) - 19910 if "value" to be returned is

equal in magnitude to R3 reset

value to be returned = 0 endif

The "value" returned will be zero ornegative. This search limits itself todepth R3 at a time by setting a nodeon the edge of the current level to the

highest possible value, zero, so that itwill be expanded only after the cur-rent layer has been expanded to theedge. The value R3 could be placedwithin the initialization subroutine of9500.

The limited depth-first searchlessens the disadvantages of the puredepth-first search by providing for aneventual exhaustive search of thelower level of the tree. But it is also acompromise: if a goal node is locateddeep and on the left-hand side of atree, this node will be more quicklyfound by the pure depth-first searchthan by the limited depth-first search.(In general, the effectiveness of bothdepth-first searches is extremelydependent on the left-right position ofa goal node within the tree.)

Notes on Experimentation

We now have the tools with whichto examine the exhaustive searchalgorithms. The BASIC programSEARCH (when fitted with the ap-propriate subroutine at 9900) will askfor the beginning puzzle (given rowby row, with A through E repre-

senting 10 through 15 in the order-4version only, and a period repre-senting the space in the puzzle), listnodes as they are expanded andgenerated, and print out the solvedpuzzle. If you want to avoid typing ina puzzle every time you run the pro-gram, add the following lines:

9521 Q2$ = "< puzzle to be

entered > "9523 GOTO 9550

My observations and experimentsare based on the sample 8-puzzlesgiven in figure 8; a given puzzle willbe referred to by its row and columnnumber in this figure. Note that therow number is the number of movesin the solution of the puzzle and thata given puzzle is a subproblem ofevery puzzle below it and in the samecolumn.

Table 3 gives data on selectedpuzzles using the breadth- and limiteddepth-first algorithms. Rememberthat closed nodes are those that havebeen expanded for successors andopen nodes are those that have beenText continued on page 98

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(3a)

Puzzle

Solution

#Open

#Closed

Total

(1,1)

L

3

1

4

(1,2)

U

3

1

4

(2,1)

UL

7

4

11

(2,2)

LU

6

3

9

(2,3)

LL

4

3

7

(3,1)

" LUL

9

8

17

(3,2)

ULU

7

6

13

(3,3)

ULL

10

9

19

(4,1)

DLUL

12

11

23

(4,2)

LULU

10

9

19

(4,3)

RULL

16

21

37

(3b)

■

Puzzle

Solution

#Open

#Closed

Total

(1,1)

L

3

1

4

(1,2)

U

3

1

4

(2,1)

UL

11

12

23

(2,2)

LU

8

7

15

(2,3)

LL

10

9

19

(3,1)

LUL

11

13

24

(3,2)

ULU

9

7

16

(3,3)

ULL

12

17

29

(4,1)

DLUL

9

8

17

(4,2)

LULU

7

6

13

(4,3)

RULL

16

21

37

(3c)

Puzzle

Solution

Depth (n)

#Open

#Closed

Total

(2,2)

LU

2

6

3

9

3

6

5

11

4

8

7

15

5

12

11

23

(2,3)

LL

2

4

3

7

3

6

5

11

4

10

9

19

5

12

17

29

Table 3:

Experiments with SEARCH. In the breadth-first search (3a),

# Open"

refers to the number of nodes created but not yet expanded. "# Closed" is th

i number

of nodes that have already been expanded. Since the breadth-first algorithm

searches

uniformly down the tree from the start node,

it is the most reliable of the exhaustive

search m

ethods.

The limited depth-first search (3b), with depth n=4, shows

that for all p

uzzles on

level four, the number of nodes that this algo)

■ithm generates

s the same or

less than

the breadth-first search. By

varying the cutoff depth, n, this a

'gorithm does

a depth-

first search in "layers" (see 3c), each layer being n nodes deep

As n becomes greater

than the

number of moves

in the solution (in this case, two), the algorithm more

closely resembles a pure depth-first search in

its inefficiency.

96 September 1981 © BYTE Publications Inc

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Text continued from page 95:

generated but not yet closed (expand-ed); thus, the total number of nodesgenerated by an algorithm is the sumof its open and closed nodes.

Also remember that the SEARCHprogram generates successors byexpanding in the following order:down, left, up, right. Although this isless important for more advancedsearches, it is extremely important

Goal NodeRow Number

(1) One move away

when analyzing exhaustive searches.

Observations and Questions

Please consider the following ques-tions before you read the answers onpage 102. On the breadth-first search:

• Note that the number of nodes ex-panded to get a solution varies withthe directions used in the solutions;

1

2

3

4

5

6

7

8

1

2

3

1

2

3

4

5

6

4

5

7

8

7

8

6

1

2

3

1

2

3

1

2

3

4

6

4

5

4

5

6

7

5

8

7

8

6

7

8

1

2

3

1

3

1

2

3

4

6

4

2

5

5

6

7

5

8

7

8

6

4

7

8

1

2

3

1

3

1

2

3

7

4

6

4

2

5

5

6

5

8

7

8

6

4

7

8

(2) Two moves away

(3) Three moves away

(4) Four moves away

Figure 8: A table of 8-puzzles used in the text. Ignoring the row with the goal node,each puzzle is referred to by its row and column numbers (eg: the rightmost puzzle inthe row labeled "two moves away" is puzzle (2, 3). Notice how puzzles in the same col-umn are related to each other: each puzzle is a subproblem of the puzzle that appearsdirectly below it.

"downs" and "lefts" tend to make thesolution shorter, while "ups" and"rights" make it longer. Compare thepuzzle (2,3) with the puzzle at (2,1),and puzzle (4,2) with (4,3).

• (Question 1) How is this tendencyreflected in the number of nodes onthe closed list? (Consult the text box,"Answers," on page 102.)

• (Question 2) Then why does puzzle(3,2), with solution LUL, generatemore nodes than puzzle (3,1), whichhas solution ULU? Aren't L moves ex-panded before U moves?

• Notice that both puzzles (1,1) and(1,2) have the same number of openand closed nodes, even though thesolution, L, in (1,1) precedes the solu-tion, U, in (1,2). This is because theSEARCH program generates all thevalid successors of the node being ex-panded before evaluating them forgoal status.

• (Question 3) I noticed a curious factwhile examining the solution of twopuzzles, one of which is a subproblemfor the other: the subproblemgenerates a node that the larger prob-lem does not. Run puzzles (2,1) and(3,1) using the breadth-first sub-routine and list the nodes generated.Where is the node in question? Whyis it generated in (2,1) and not in(3,1)?

1 23

4 56

©@GOAL

• 78

@©

Figure 9: Solution of puzzle (3, 1) by the breadth-first algorithm. The tree is a partialtree carried out only far enough to reach the goal node (shown in the bottom row). Thecircled numbers in black indicate the order in which nodes are expanded to solve thepuzzle. The node labeled B is the start node of puzzle (2, 1), a subproblem of puzzle (3,1); circled numbers in color indicate the order in which nodes are expanded to solvepuzzle (2, 1).

98 September 1981 © BYTE Publications Inc

On the depth-first search:

• You will probably find that you runout of memory (or patience) beforeyou get a solution from the depth-first algorithm. This is because thealgorithm first dives to the bottom ofthe tree, and that bottom is deep,even for a puzzle as small as theorder-3 8-puzzle. Try experimentingwith the depth-first algorithm, usingthe SEARCH program set to handlethe order-2 puzzle.

On the limited depth-first search:

• Table 3b shows the results from thesolution of the same puzzles, (2,2)and (2,3), using different cutoffdepths (variable D3 in line 9900).Since both puzzles are solved in twomoves, the cutoff depth simply deter-mines how far down the search will

Text continued on page 102

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Text continued from page 98:

go before returning to shallowerdepths.

• The definition of a limited depth-first search of level n is that it expandsn — 1 levels at a time, generating thecurrent level n nodes but not im-mediately expanding them. There-fore, such a search is most efficientwhen the level of the search is equalto the number of moves in the solu-tion: the search drops down the left-most side of the tree, stops at level n,

and scans across the n-level subtreefrom left to right.

• I made an unexpected discovery:the limited depth-first search isguaranteed to expand less than or thesame number of nodes as the breadth-first search when the depth of thesearch (n) is equal to the number ofsteps (s) in the solution. An intuitiveproof of this can be seen from theexample of figure 11. Also, it can beinferred that the two searches are

Answers

1. If a given step of a solution is oneof the last to be expanded (say, up orright), then the breadth-first searchwill first expand in other, nonproduc-tive ways (remember the order: down,left, up, right). It is the expansion ofthese nodes that increases the numberof nodes on the closed list.

2. Yes, L moves are expanded be-fore U moves, but an analysis of thesituation shows that the order in whichnodes are expanded (down, left, up,right) is only one of several factorsinfluencing the number of nodes ex-panded by a breadth-first search. Referto figures 9 and 10. If you count thenumber of terminal nodes (which areopen—yet to be expanded) and nonter-minal nodes (representing closed, oralready expanded nodes), you will findthat the numbers agree with thoselisted in table 2a. (Remember to countthe start node as being closed; also, forthe moment, ignore node C in figure9.)

The two trees are identical innumber and distribution of nodesthrough rank two fie: in nodes 1through 9). The overwhelming reasonthat puzzle (3,1) expands more nodesthan puzzle (3,2) is that the former hasto expand more level-two nodes to getto the goal node. Why is this? Because,from node 3 (in both trees), the pathleading to the goal node in puzzle(3,2)—the L branch in figure 10—is ex-panded before the correspondingpath—the U branch in figure 9—is ex-panded. Here the single L in the solu-tion of puzzle (3,2) is more importantthan the two L s in the solution of (3,1)because it prevents the expansion ofseveral "fertile" nodes (nodes six andseven in figure 9) on the next-to-lastlevel.

We should not, however, betempted to generalize. The factors in-fluencing the number of nodesgenerated are so interdependent that itis impossible to evaluate their relativestrengths outside the context of aspecified example.

3. Refer to figure 9. The entire tree(minus node C, in color) is the solutiontree for puzzle (3,1). The nodes in thecolored box (including node C) are thesolution tree for puzzle (2,1).

Now the reason for the fact thatnode C is generated only by (2,1)becomes clear. When node B is a startnode, all four directions generate validsuccessors, but when node B isgenerated by starting node A in puzzle(3,1), the SEARCH program rightlydenies node C successor status becausethe direction of the move from B to Cundoes the move directly before it, Ato B. Here again, the interaction offorces in the algorithm create unex-pected but correct results.

4. The two important factors in thissituation are the depth and the "left-ness" of the goal node. Because thelimited depth-first algorithm scansfrom left to right, the "leftness" of thegoal node is the more important factor:a node midway in the tree but closer tothe left edge of the tree than anothernode (which is further down), will beexpanded first. This is also true for apure depth-first search.

5. A limited depth-first search oforder one is equivalent to a breadth-first search; that is, because n = 1, thealgorithm does an exhaustive search ofthe tree one level at a time. Numberingthe nodes of a tree according to thelimited depth-first algorithm willdemonstrate the equivalence of thetwo forms.

102 September 1981 © BYTE Publications Inc

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approximately equivalent in effi-ciency when n is only slightly largerthan s.

• (Question 4) In a limited depth-firstsearch of level n on a puzzle with asolution of n moves, what are the two

most important characteristics (interms of the location of the goal node)that influence the solution time of thepuzzle? Which is more important?• With limited depth-first searches ofdepth greater than the number of

135

426 (lO)78 •

1354-2 (jl)

786

453 Qg)

786

Figure 10: Solution to the puzzle (3, 2) by the breadth-first algorithm. The circlednumbers to the right of each node indicate the order in which they are expanded. Nodes8 through 13 (six nodes) are "open" (ie: they have not yet been expanded), whereasnodes 1 through 7 are "closed."

DEPTH0

= BREADTH-FIRST■ = LIMITED DEPTH-FIRST

(lib)

DEPTH0

Figure 11: A comparison of search efficiency. The limited depth-first search alwaysproduces the same or fewer nodes than the breadth-first search, when the depth of thesearch is equal to the depth of the goal node. An example of the efficiency of the limiteddepth-first search is shown in figure 11a, where the breadth-first search (indicated incolor) has produced more nodes. In figure lib, the two types of searches produce anequal number of nodes, using the same partial tree but a different goal node. Thebreadth-first search must always expand the entire tree to depth n — 1, whereas thelimited version may not, depending on the location of the goal node.

104 September 1981 © BYTE Publications Inc

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DEPTH0

AREA (o)

Figure 12: A comparison of four exhaustive searches. Given the partial tree with goalnode on level six, the four lines A, B, C, and D delineate the nodes expanded by thefollowing searches:

A limited depth-first search, with n=s = 6

B limited depth-first search, with s an even multiple of n (s = 6, n=3)

C breadth-first search

D limited depth-first search with s not an even multiple of n (s=6, n=4)

The worst case for the limited depth-first search, given by D, expands more or fewernodes than the breadth-first search, C, depending on whether area a or area b has morenodes.

moves in the problem solution(n > s), the number of nodes ex-panded increases with the differencebetween the two (see the results oftable 3b).

• When the depth of the search is lessthan the number of moves in the solu-tion (rc < s), two cases occur. If s is amultiple of n, the efficiency of thesearch is between that of a breadth-first search and a limited-depth searchwith n = s (as illustrated in figure12). If, however, s is not a multiple ofn, the result is mixed. The depth-firstsearch will go several levels deeperthan the level of the solution and maybe better or worse than a breadth-firstsearch depending on the number ofnodes expanded past level s and thenumber of nodes expanded in thebreadth-first search that are not ex-panded in the limited depth-firstsearch (see figure 12).

• (Question 5) A depth of one(n = 1) gives a special case of thelimited depth-first search. What isanother name for this search?

Conclusions

We've covered quite a bit of

material in this article, including anintroduction to tree- and graph-searching terminology, a definition ofthe finite-state representation of aproblem, the general-purpose searchalgorithm implemented in the BASICprogram SEARCH, and three exhaus-tive-search algorithms. In most cases,a breadth-first search is the best of thethree, but in some cases it can be im-proved upon by the limited depth-first search.

Part 2 will deal with heuristicalgorithms that estimate the "worth"of a given node in order to arrive at aguaranteed solution without perform-ing an exhaustive search. ■

References

1. Nilsson, Nils J. Problem-Solving Methodsin Artificial Intelligence. New York:McGraw-Hill, 1971. An excellent book onall aspects of this subject as well as therelated topics of problem reduction,theorem-proving, and the searching ofgame trees.

2. Winston, Patrick Henry. Artificial In-telligence. Reading MA: Addison-Wesley,1977. A good overview of artificial in-telligence with one section devoted totree searching.

106 September 1981 © BYTE Publications lnc

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6 Brand New Books from Osborne/McGraw Hill

Interfacing to S-100

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by Gordon Eubanks, Adam Osborne, and Martin McNiffThe CBASIC language j*iay be the most advancedversion of BASIC yet "created. Like Pascal, CBASICrequires no line numbers and lends itself to highlyorganized, structured programs—programs that arereadable, modular, and easier to change. CBASIC isas easy to learn as BASIC and contains convenientfile handling facilities, making it very useful for manybusiness applications. It may be the only computerlanguage you'll ever need to learn. This guide wasco-authored by Gordon Eubanks, the creator ofCBASIC. It is not only a self-teaching textbook, it isthe definitive reference on the CBASIC language.:, \ #61-6 $15 D

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Book Review

Turtle Geometry

by Harold Abelson andAndrea A diSessaMIT Press,

Cambridge MA, 1981,478 pages, S20.00

Reviewed byW Lloyd Milligan8604 Maywood DrColumbia SC 29209

Imagine four turtles, eachsitting at one corner of asquare. At the same moment,each turtle begins to crawl ina clockwise direction towardits nearest neighbor. Theycontinue crawling at the samespeed toward one anotheruntil they meet. How long isthe path traveled by each tur-tle?

The solution to this well-known problem—that thepath equals an edge of thesquare—is reached most easi-ly by working from theturtle's point of view. A tur-tle is a small creature that in-habits a computer's graphic-display screen. It has theability to move forward orbackward a specified distanceand to turn in place clockwiseor counterclockwise througha given angle. Distances andangles are arguments in turtlecommands. Just as straight-edge and compass are thebasic tools of traditionalgeometry, so the turtle is theimplement of turtlegeometry.

Turtle Geometry, byHarold Abelson and AndreaA diSessa, discusses using thecomputer to explore mathe-matics. The authors make apersuasive case for their ideathat compared with tradi-tional methods, the computa-tional approach encouragesmathematical exploration atan earlier stage of learning.

The turtle leads the learneron quite a different mathe-matical journey than does

traditional geometry. Theearliest ideas presented in thisbook later are found to bearimportant relationships totopological concepts. We firstlearn of the distinction be-tween intrinsic and extrinsicproperties—intrinsic proper-ties are those that do not re-quire a frame of reference fortheir expression. A secondimportant distinction con-cerns local versus global rep-resentations. Circles are con-structed locally, meaning thatthe turtle does not knowabout the rest of the planewhen making a small piece ofa circle. Many of the turtle'sconstructions are both intrin-sic and local.

Remember that the turtlecan turn in place through anyspecified angle. If he keepstrack of his turning by addingall clockwise turns and sub-tracting all counterclockwiseturns, he immediatelydiscovers the Closed-Paththeorem:

The total turning along

any closed path is an integer

multiple of 360 degrees.

The approach of turtlegeometry is empirical. Youobtain a result like theClosed-Path theorem, thentry to improve it, exploringits consequences for variouskinds of paths. Before longyou have made a new dis-covery, perhaps in a differentbranch of mathematics. It is atribute to the richness of tur-tle geometry that by the endof the first chapter you arestudying the Euler <f> functionand Fermat's "Little"theorem, both number-theoretic ideas.

Because the turtle is ananimal, it is only natural toexplore turtle movement asbehavior in response to con-trolling stimuli. Much can belearned by programming theturtle to model various types

of forced movement, such asmovement toward or awayfrom stimulation. (For ex-planations of forced move-ment, see Orientation inAnimals by G Fraenkel andD Gunn. Dover, 1961.) Youcan even set up experimentsin which the turtle is respond-ing to information from morethan one sense simultaneous-

ly.

The turtle can be used formodeling patterns of growthfound in nature. The princi-ple of uniform growth leadsto the shape of an equi-angular (logarithmic) spiral.Many other fascinatingdesigns, such as the spiralshapes found in seashells,arise from invoking simpleturtle procedures recursively.(See On Growth and Form,by D Thompson. CambridgeUniversity Press, 1961.)

The book provides apainless introduction to vec-tor methods. The brief excur-sion into linear algebra is thebook's only "corruption" (byCartesian analytic geometry)of turtle geometry, and it isboth appropriate and worth-while. You learn here how torepresent three-dimensionalobjects in two dimensions.Parallel projection ispresented first, then perspec-tive projection. Anyone whoappreciates arcade games oris interested in their designwill find this chapter en-lightening. The geometricbases of changing perspec-

tive, zooming, and the likeare explained.

Any computer with goodgraphics may be used to im-plement turtle geometry. (Acommercial version is avail-able for the Apple.) A well-structured language such asPascal is desirable, but notessential, to implement theturtle routines.

Inevitably, the turtleescapes from the plane. Tur-tle spherical geometry is thefirst nonplanar generaliza-tion. A beautiful local defini-tion of geodesic is developed:

A turtle line is anequal-strided turtle walk.

Equal-strided means the tur-tle's left and right sides moveequally. The beauty of thisdefinition is that it applies toany surface. Remember, thetotal turning around a closedpath is an integer multiple of360°. As it turns out, the tur-tle can execute a closed pathon nonplanar surfaces with anet 360° change in heading,but a total turning not equalto 360°. The discrepancy canbe detected intrinsically. Theconcept, called angle-excess,gives rise to the importantproperty called curvature.Further exploration brings usto the domain of topology,where we encountertheorems such as, "Any one-holed torus (doughnut-shaped surface) has zero totalcurvature."

Articles Policy

BYTE is continually seeking quality manuscripts written by indi-viduals who are applying personal computer systems, designingsuch systems, or who have knowledge which will prove usefulto our readers. For a more formal description of procedures andrequirements, potential authors should send a large (9 by 12 inch,30.5 by 22.8 cm), self-addressed envelope, with 28 cents USpostage affixed, to BYTE Author's Guide, POB 372, Hancock NH03449.

Articles which are accepted are purchased with a rate of up toS50 per magazine page, based on technical quality and suitabilityfor BYTE's readership. Each month, the authors of the twoleading articles in the reader poll (BYTE's Ongoing Monitor Box or"BOMB") are presented with bonus checks of $100 and S50.Unsolicited materials should be accompanied by full name andaddress, as well as return postage.

108 September 1981 © BYTE Publications Inc

We'reour own

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BYTE September 1981 109

Book Review.

Any surface in threedimensions can be deformedinto a piecewise-flat surface.Piecewise-flat means, simply,that the surface is made offlat pieces joined at the edges.If the edges are straight, thenall of the curvature is concen-trated in the vertices.Piecewise-flat surfaces areeasily represented in a com-puter program by an atlaswhich specifies all matchingedge pairs by their face andedge numbers. Since apiecewise-flat deformationpreserves all the topologicalproperties of a surface, theseproperties can be studied as

they are exhibited in thisspecial case. For example, animportant theorem, Gauss-Bonnet, states that the totalcurvature of any closed sur-face is:

2rr( V-E+F)

where V is the number of ver-tices, £ the number of edges,and F the number of faces.

The turtle's wanderingstake him, finally, to the do-main of curved space andgeneral relativity theory.Gravity as a property ofgeometry is presented in aparable about a turtle who

lives near the north pole of asphere. He constructs a two-dimensional Euclidean modelof his experience. Inevitably,the turtle encounters variousstrange problems with hismodel. He eventually over-comes his difficulties bypostulating a force which actseverywhere locally. Theforce is called "demon-turning."

Traditionally, mathematicshas shunned the computa-tional approach. The mainthesis of Abelson anddiSessa's book is that ex-perimentation using a com-puter stimulates mathe-

matical discovery. The thesisis certainly true of turtlegeometry, and one suspects itapplies to many other areasof mathematics. Reading thisbook with the help of a goodgraphics computer system,you are sure to discover newand interesting math. TurtleGeometry is a serious effortto blend the computer withmathematics. It would serveas an excellent textbook orself-study guide. Perhaps itwill also serve as a model forother efforts to bring thecomputer and mathematics tofruitful collaboration. ■

BYTE's Bugs

Corrected Price

In the June 1981 BYTE, Ax-lon Inc's 8-slot bus expansionboard was incorrectly priced.(See page 420.) The boardcosts $895. The company hasalso released new pricing onthe RAMCRAM memorymodule. It now costs $225.

Blasted Bugs

In the August 1981 BYTE"Software Received," theprice for Budgeco's RasterBlaster was incorrectly listed.The correct price is $29.95.

We apologize for themistake.

Super Simple Bug

An integrated circuit wasincorrectly labeled in JamesNicholson and Roger Camp'sarticle "Build a Super SimpleFloppy-Disk Interface, Part1." (See the May 1981 BYTE,page 360.)

In Figure 4b on page 372,IC9 should be numbered

74193. The pin numbers arecorrect as shown.

Color PEEKS

Stan Miastkowski's article"Extended Color BASIC forthe TRS-80 Computer" hasbeen the focus of much atten-tion. (See the May 1981BYTE, page 36.) It seems thatthe system does indeed in-clude a PEEK function, con-trary to what was previouslyprinted. The author replies:

/ admit that I goofed. ForBYTE to run an article on Ex-tended Color BASIC at aboutthe time it became widelyavailable in Radio Shackstores, the company pro-vided me with one of the firstproduction models and arough draft of the documen-tation. The rough manualhad a list of differences, oneof which showed that PEEKwas not available in thenonextended model of theTRS-80 Color Computer. Itwas, however, available bythe time the manual reachedits final stages, but that wastoo late for inclusion in thearticle.

Last One Out

In John Sauter's article"Faster BASIC for the OhioScientific" (May 1981 BYTE,page 236), an error wasdiscovered in listing 3 onpage 240. The last line, an"INY", should be omitted—itis not part of the "ROR A"macro.

For those using Microsoft'sKIM or TIM BASIC, the new

code would be as shown inlisting 1.

Another bug was foundwhen using the 5-inch diskversion. The code to bepatched is on track 04, not 03as published. Also, when us-ing smaller disks, the topmemory should be set athexadecimal 4200 as opposedto hexadecimal 47FF for thelarger 8-inch disks. ■

Listing 1

$37C2

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$04,X

$37D7

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BLA

$37D8

6A

ROR

A

$37D9

C8

INY

$37DA

DO E8

BNE

$37C4

$37DC

18

CLC

$37DD

60

RTS

($37DE through $3801 now

unused)

$38C3

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ROR

$73

$38C5

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ROR

$74

$38C7

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ROR

$75

$38C9

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$76

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$38CD

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TYA

$38CE

4A

LSR

$38DF

DO D6

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(S38D2 through $3903 now

unused)

110 September 1981 © BYTE Publications Inc

Turn your Apple into the world'smost versatile personal computer.

The SoftCard™ Solution. SoftCardturns your Apple into two computers.A Z-80 and a 6502. By adding a Z-80microprocessor and CP/M to yourApple, SoftCard turns your Apple intoa CP/M based machine. That meansyou can access the single largest bodyof microcomputer software in exist-ence. Two computers in one. And, theadvantages of both.

Plug and go. The SoftCard systemstarts with a Z-80 based circuit card.Just plug it into any slot (except 0) ofyour Apple. No modifications required.SoftCard supports most of your Appleperipherals, and, in 6502-mode, yourApple is still your Apple.

CP/M for your Apple. You get CP/Mon disk with the SoftCard package. It'sa powerful and simple-to-use operatingsystem. It supports more softwarethan any other microcomputer operat-ing system. And that's the key to theversatility of the SoftCard/Apple.

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BASIC included. A powerful tool,BASIC-80 is included in the SoftCardpackage. Running under CP/M, ANSIStandard BASIC-80 is the mostpowerful microcomputer BASICavailable. It includes extensive disk I/Ostatements, error trapping, integervariables, 16-digit precision, exten-sive EDIT commands and string func-tions, high and low-res Apple graphics,PRINT USING, CHAIN and COM-MON, plus many additional com-mands. And, it's a BASIC you cancompile with Microsoft's BASICCompiler.

More languages. With SoftCard andCP/M, you can add Microsoft's ANSIStandard COBOL, and FORTRAN, or

Basic Compiler and Assembly Lan-guage Development System. All, morepowerful tools for your Apple.Seeing is believing. See the SoftCardin operation at your Microsoft or Appledealer. We think you'll agree that theSoftCard turns your Apple into theworld's most versatile personalcomputer.

Complete information? It's at yourdealer's now. Or, we'll send it to youand include a dealer list. Write us. Callus. Or, circle the reader service cardnumber below.

SoftCard is a trademark of Microsoft. Apple II andApple II Plus are registered trademarks of AppleComputer. Z-80 is a registered trademark of Zilog,Inc. CP/M is a registered trademark of DigitalResearch. Inc.

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One Step Forward—Three Steps Backup

Computing in the US Space Program

A special tension surrounds the de-velopment of a computer system foruse as the main computer aboard aspacecraft. On one hand, such a com-puter must be able to perform com-plex operations. On the other, sincethe first extraterrestrial service call bya field engineer is yet to be made, anon-board computer system must doits work with absolute reliabilitydespite the most demanding envi-ronmental conditions. And by thetime a computer's reliability has beenproved beyond a doubt, more effi-cient computers have appeared on themarket. It's almost as if the same pro-cess that proves a computer's reliabil-

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ity also ensures that the computer willbe obsolete before it flies. Developinga main on-board computer is both abattle to prevent a catastrophicfailure and a race against obsoles-cence.

The advent of the space shuttle(known more formally as the SpaceTransportation System) will soon en-hance the requirement for reliability

on orbital missions. Moreover, theshirt-sleeve environment of Spacelabwill prove an opportunity to use off-the-shelf microprocessor systems tosupport scientific experiments. Butspace-rating—establishing the fitnessof hardware for use aboard a space-craft—will remain a severe test, espe-cially for computers that control life-critical and mission-critical systems.In this article, I'll first discuss therequirements of space-rating. ThenI'll describe the tasks that a main on-board computer must perform andsome of the capabilities needed toperform those tasks. I'll go on to dis-cuss the problems of providing

112 September 1981 © BYTE Publications Inc

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After a glance at the historical de-velopment of on-board computers,I'll look at some devices now in use.Finally, I'll describe applications ofmicroprocessors in noncritical func-tions aboard spacecraft. (Yes, therewill soon be an Apple in orbit.)Throughout the article, I will confinemy comments to civilian spacecraft ofthe United States.

Space-Rating

Equipment and software that mustoperate for long periods unattendedin the difficult environment of spacemust be very reliable. Space-rating isthe process that demonstrates the reli-ability of equipment for use on space-craft. The process requires carefultesting of parts, components, assem-blies, modules, and software. Space-rating standards are stricter thanspecifications for military equipment.

Here are a few of the things that amain on-board computer in themid-1980s must be able to do:

• withstand repeated heating andcooling from +50° Celsius to -10°Celsius

• function despite exposure to mecha-nical shocks, electromagnetic distur-bances, high-energy particles, andradiation

• withstand forces from 0 to 30gravities

• perform calculations on the level ofevaluating 1300 long time-series poly-nomials per second to 32 bits of preci-sion

• undergo intensive use for periods ofseveral years without experiencing asingle failure

Although space-rating standards ofreliability are always stringent, theydepend to some extent on the kind ofmission for which the spacecraft is in-tended.

Mission Classes

Missions usually fall into one ofthree classes: manned missions,

planetary-probe missions, and un-manned earth-orbiting missions.

Manned missions require thehighest standards of reliability. Whenan astronaut's life is at stake, there isno room for failure. This principle isreflected in the record of the Apolloprogram: as a result of 2000 man-years of development and testing,there were no flight-critical errors ofspacecraft software (see reference 8).

The most common way to establishreliability in spacecraft equipment isto build in redundancy. The ShuttleOrbiter vehicle, for example, has fivegeneral-purpose computer systems tocontrol all aspects of its operation. In

of a rule that the Shuttle Orbiter willnot be allowed to approach "dead"spacecraft. Unless telemetry indicatesthat an unmanned satellite still has ef-fective attitude-control and a certainlevel of stability, the Orbiter crew(and the extremely expensive Orbiteritself) will not be committed to ap-proach the satellite. In addition, anysatellite intended for launch as a shut-tle payload must pass the same strin-gent requirements as a manned space-craft.

Although no lives are at stake intheir use, planetary-probe spacecraftalso impose stringent requirements onon-board computer sysems. The long

Photo 2: Shuttle Orbiter mounted on transport aircraft. The Orbiter has five on-boardcomputer systems, configured to provide as many as three levels of backup in criticalsituations. Two chase planes are visible.

certain critical operations, four of thefive systems will perform the sametask, providing three levels ofbackup.

More recently, concern for the livesof astronauts has led to the adoption

flight times to distant targets, thehostile environments traversed, andthe impossibility of retrieval or repairall increase the demands placed onequipment. Planetary-probe space-craft are very much on their own.

114 September 1981 © BYTE Publications Inc

Circle 267 on inquiry card.

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The distance between spacecraft andearth is often so great that radiosignals require long periods to travelbetween the two. When the target isone of the outer planets, communica-tion may take more than a half houreach way. By the time the ground sta-tion receives a message indicating aproblem aboard the spacecraft, toolittle time may remain to send mes-sages intended to correct the prob-lem. The design requirements forcomputer systems aboard planetary-

probe spacecraft are perhaps an orderof magnitude beyond those for sys-tems aboard spacecraft operatingnear earth.

Most spacecraft carry out un-manned earth-orbiting missions.These missions may have either near-earth orbits or synchronous-altitudeorbits. Spacecraft can remain syn-chronous with the rotation of theearth only by orbiting at extremelyhigh altitudes. Since the Shuttle Or-biter can't deploy or retrieve space-

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craft so far from earth, synchronous-altitude spacecraft must be built tofunction without service for the dura-tion of their missions.

A spacecraft at synchronousaltitude appears to remain stationaryabove one point on the earth'sequator. Consequently, a ground sta-tion can stay in continuous com-munication with such a spacecraft. Inthis respect, spacecraft at syn-chronous altitude are easier tomanage from the ground.

Satellites orbiting the earth atlower altitudes appear to "rise" and"set" over the ground station. Atypical orbit takes about 90 minutes,and the spacecraft is in view of agiven tracking station for only 10minutes of the 90. The ground stationmust pack a great deal of communica-tion into the 10 minutes of contact.During those 10 minutes, the groundstation has to send up enough com-mands for the next 80 minutes of op-erations, check the state of all on-board systems, take any necessarycorrective action, and dump recordeddata from the satellite to the groundover a high-speed channel.

During the 80 minutes when thesatellite is out of touch with theground, the on-board computer mustsequence and monitor spacecraft op-erations and components and storemessages about the status ofmonitored equipment. In case ofproblems, the on-board computermust take first-order corrective ac-tion. Even with the advent in theearly 1980s of NASA's tracking sta-tion in the sky—the synchronous-altitude Tracking and Data RelaySatellite System (TDRSS)—fullcoverage of satellites in near-earthorbits will not be assured because somany satellites will share use ofTDRSS.

Space-Rating Microprocessors

Microprocessors, memories, andinterface devices aboard spacecraftmust operate in a vacuum over a widetemperature range. The vacuum re-stricts cooling to radiation and con-duction; since no atmosphere is pres-ent, convection is impossible. Besidesthe limitations on cooling, equipment

116 September 1981 © BYTE Publications Inc

Circle 137 on inquiry card.

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must be able to withstand a wide tem-perature variation while dormant.The dormant period includes launchand recovery, during which there isno assurance that the spacecraft canmaintain adequate thermal control.

Periodic and random vibration andmechanical shock may also damageelectronic equipment during thelaunch phase. A common failure isbreakage of a bonded lead wire whereit is attached to the die of an inte-grated circuit. High inertial gravity(g) loads can cause such breakage.Space components are usually testedin steady-state acceleration in excessof 30 gs. Instantaneous accelerations,such as those undergone by a chipthat is dropped onto a solid floorfrom a height of approximately ameter, can exceed hundreds of gs.

Components of space-borne sys-tems must neither generate electro-magnetic disturbances nor be vulner-able to them. The proximity of otherelectronic devices and of moderate-power transmitters of radio-fre-quency energy requires resistance toelectromagnetic disturbances.

The abundance of radiation andhigh-energy particles pose anotherthreat to semiconductor devices inspace. Although there is a self-healingeffect if semiconductors are turned offfor a while, periodic failures are unac-

ceptable in mission-critical functions.

Table 1 shows the radiation "hard-ness" of several microprocessors. Ingeneral, radiation damage is cumula-tive. Microprocessors of commercialgrade fail at several thousand radstotal dosage. Although it is possibleto attempt shielding chips withaluminum paneling, results are notencouraging. Often, when one high-energy particle strikes the aluminum,more than one high-energy particlecomes out the other side.

P-type metal-oxide semiconductors(PMOS) are generally less susceptibleto radiation damage than are thenewer and faster N-type metal-oxidesemiconductor (NMOS) devices.Radiation-hardened versions of stan-dard device-families are available,particularly complementary metal-oxide semiconductor (CMOS) de-vices, which are faster than PMOSbut slower than NMOS. This is butone instance of space-borne tech-nology lagging behind current com-mercial technology.

Perhaps the most serious hurdlethat microprocessors must face beforebecoming main on-board computersis one of sheer computational power.Many of the calculations required ofthese machines need a word lengthgreater than 16 bits. Until the ap-pearance of 32-bit microprocessors,

Power of

Suitable

Projected

Basic Pro-

Tech-

Support

Hardness,

cessor, in

Device

Type

nology

Circuits

in Rads

Milliwatts(mW)

RCA 1802*

Monolithic

CMOS

Memories,Some I/O

105

30

TI-SBP9900

Monolithic

l2L

MemoriesOnly

10'

500

Intersil 6100

Monolithic

CMOS

Memories,Some I/O

105

50

Intel 8080A

Monolithic

NMOS

Memory,Some I/O

103

1700

AMD 2900*

Bit Slice

LS-TTL

Memory,All I/O

107

10,000(16 bit)

Intel 3000*

Bit Slice

S-TTL

Memory,All I/O

10'

15,000(16 bit)

NMI 6700

Bit Slice

LS-TTL

Memory,Some I/O

107

15,000(16 bit)

* Multiple sources available.

Table 1: Comparison of

microprocessors for space

applications.

Included are

each processor's radiation

"hardness'

and its average power consumption.

less highly integrated devices will re-tain their monopoly as main on-board computers.

On-board Computer Tasks

Designers of spacecraft have beenrelying more and more on on-boardcomputers and associated data sys-tems to give the spacecraft flexibilityand autonomy. Tasks assigned to theon-board computer include:

• Attitude determination. Orientingthe spacecraft in space is a vital andcomplex function. The spacecraftdata system must give the computerdata from sun- and star-trackers,earth sensors, and gyros. The atti-tude-determination algorithm calcu-lates how the spacecraft should bealigned with respect to inertial axes.The attitude-control algorithm thenissues commands that enable magnet-ic thrusters, jet torquers, or reactionwheels to point the spacecraft (ie:align the axes) to a desired point onearth or to a star. Attitude determina-tion and control, sometimes includingorbit-adjust software, typically re-quire 4 to 12 K bytes of memory.

• Command Storage. The on-boardcomputer can store sequences of com-mands that are "time-tagged" for laterexecution. Storage may also includepredefined blocks of frequently ex-ecuted command sequences (macros).

• Executive. A real-time, multitask-ing, interrupt-driven executive is usedto sequence all tasks and to handleinput/output operations.

• Housekeeping. This includes moni-toring and controlling thermal andelectrical power. These tasks may re-quire continual monitoring and limit-checking of sensors in the spacecraft.Spacecraft housekeeping may also in-clude continuous measurement of thebatteries' charge.

• Telemetry Format Control. The on-board computer may control thesampling and format of the on-boardtelemetry points. This makes re-configuration possible in response todegradation and failures. If a prede-

118 September 1981 © BYTE Publications Inc

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Photo 3: ATS-6 Communications Satellite. Traveling in synchronous orbit, the ATS-6 uses two on-board computers for attitudecontrol.

fined telemetry format is changed inorder to circumvent a hardware prob-lem, the input on the ground-basedtelemetry processor must, of course,be changed, too.

• Instrument Sequencing and Con-trol. The on-board computer canmonitor and control instrumentsdirectly or can support the in-struments' dedicated microproces-sors. In addition, the on-board com-puter can manage storage of data.Data is recorded during the "back or-bit," when the spacecraft is out oftouch with the ground station. Whenthe spacecraft reestablishes contact,data is dumped to the ground over ahigh-speed data link.

Some Essential Capabilities

On-board computers must con-stantly perform complex mathemat-ical computations such as coordinatetransforms. Floating-point capabilityenables on-board computers to per-form these computations efficiently.

The alternative to building in float-ing-point capability has been to usescaled fixed-point operations. In test-ing, operation, and maintenance,however, the scaled fixed-point ap-proach has led to problems with over-flows, notably aboard Applications-Technology Satellite-6, the Interna-tional Ultra-violet Explorer, and theSolar Maximum Mission. These expe-riences have led to the choice of in-tegral floating-point capability in the

on-board computers' processors.

Designers may implement floating-point capability in several ways. Themost attractive is to have floating-point capability as part of themachine architecture. The architec-ture of several on-board computersystems in the 1980s will implementfloating-point capability. If a pro-cessor can't perform floating-pointoperations, the designer can add thecapability by introducing a slave pro-cessor. The slave processor may relyon calculator or computer tech-nology, or it may be a co-processor,sharing the main processor's address,data, and control space.

Designers sometimes add firmwarecontaining math-library functions

122 September 1981 © BYTE Publications Inc

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such as SIN/COS, ATAN, andSQRT, based on the primitive float-ing-point operations. Ideally, the on-board processor would have bothfloating-point operations and math-

library functions as standard fea-tures. The co-processor and firmwareapproaches are interim measures tobe considered only so long as tech-nological restrictions prevent includ-

Processor

Approach

Used (see

table 3)

Format

Time Needed for Operationin Microseconds (/ts)

Add/Subtract

Multiply

Divide

NSSC-1/SP-C32LSI-11

ATAC-16MSAM95113571093

1b22

1b1a

24/81

24/82

24/8

24/8

8-decimal-

dlglt-

mantissa,

2-digit-

decimal

16.5

42.1 to 66.2

5.75

13.5 to 92

22,000 to

66,000

11.574 to 121

16

36.5 to 42

32,000 to

227,000

27.0151 to 232

28.5

38.5 to 46

78,000 to

223,000

80874

1c

exponent32 bits;10 decimadigits

18

18

27

1 24-bit mantissa/8-bit exponent

2 Essentially 25-bit mantissa

3 Slave processor only

4 Co-processor with 8086/8088

Table 2: Comparison of arithmetic operations in floating-point hardware.

ing these features in the main pro-cessor.

Floating-point capability (in the24-bit-mantissa/8-bit-exponent for-mat) requires at least a 16-bit and pre-ferably a 32-bit word size. Several on-board computer systems in the 1980swill have floating-point capability,and at least one of these will have in-tegral math-library functions.

Table 2 compares the floating-point capabilities of several kinds ofhardware used in on-board com-puters. Table 3 shows the advantagesand disadvantages of different waysof implementing floating-point capa-bility. Table 4 shows execution timesof math-library functions in differentprocessors.

Higher-Order Language

The complexity of the mathematicsto be performed aboard a spacecraftgives considerable appeal to the useof a higher-order language in devel-oping flight code. The computer, ofcourse, is indifferent to the program-ming language or method used. Thequestion is whether higher-order Ian-

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124 September 1981 © BYTE Publications Inc

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The finest Data BaseManager Available

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BYTE September 1981 125

Number Type of(see table 2) Approach

Advantages

Disadvantages

1a1b

Add-on arithmetic processorAdd-on microprocessor

Built-in math functions

Fast—may proceed in

parallel with main micro-

Slow

Interfacing; no-math

library

1c2

Co-processor

Functions built intomain microprocessor

processor

Faster; math-library

available

Very fast

Architecture and inter-facing problemsUsually no math-library; math functionsmust be written insoftware

Table 3

. Comparison of different approaches to floating-point capability.

Implementation Timefor Fixed-Point Calculations

(a)

Accuracy(in bits)

161816

in Microsecond

s (/*s)

Processor Used

9900, with softwareNSSC-1, with softwareLSI-11, with software

SIN/COS

109163176

ATAN/ASIN

236417544

SQRT

117190184

(b)

nt hardware

Implementation Time

for Floating-Point Calculations

in Microseconds (/ts)

Processor Used

LSI-11 with floating-poi

NSSC-1/SP-C32

ATAC-16MS

SIN/COS

784

265.2121.2

ATAN/ASIN

1303

311

235

SQRT

767223123.6

(c)

ProcessorUsed

FormatUsed

Implementation Time for Calculation

by Inherent Math-Library Functions

in Microseconds 0*s)

AM9511'

59109*

8037

Floating-Point

Decimal

Co-processor

ATAN/ASIN

1384

620,500

N/A

SQRT

206.5

186,000

36

SIN/COS

1084.25

760,500

N/A

* Average of minimum and worst case times

Table 4: Implementation times of several math functions in different processors.The functions considered are sine, cosine, arctangent, arcsine, and square root.Table 4a shows the times for fixed-point implementations. Table 4b shows thetimes for floating-point implementations. Table 4c shows miscellaneous pro-cessor/format combinations.

guages increase programmers' effi-ciency. Many programmers nowthink that they can work more effi-ciently in higher-order languages thanin assembly language.

But will the use of higher-order lan-guages make testing and maintainingsoftware more difficult? It remainsunclear, during operation of a space-craft, whether code produced in as-sembly language is easier to debugand change than code produced by ahigher-order-language compiler. Butthe experience of producing the flightcode for the Space Shuttle suggeststhat language derived from a higher-order language is no more difficult todebug and may even be easier.

Among the higher-order languagesthat are candidates for use with on-board computers are Jovial, HAL/S,and Ada/Pascal. Each has advan-tages and disadvantages. (Space Pro-gramming Language [SPL] was devel-oped by RCA for in-house use andnever gained wide acceptance.) In theabsence of an effort to develop a com-piler, however, designers will have touse whatever language is supplied bythe manufacturer of the hardware.

Pascal-like languages impose struc-tured techniques on programmers.Some programmers have faultedPascal because each program in thatlanguage is an entity, lacking externalreferences. But, in creating softwarefor flight-loads, this feature of Pascalshould be an advantage becauseflight-load software must function asan entity. Moreover, Pascal hasgained wide acceptance among pro-grammers. And the Department ofDefense has adopted Ada, a Pascal-

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126 September 1981 © BYTE Publications Inc

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BYTE September 1981 127

like language.

HAL/S was created specifically forgenerating flight software, but is notdesigned for use with a small pro-cessor. As with all higher-order lan-guages, HAL/S will only be as goodas its compiler implementation,which translates programs into ma-chine language.

The choice of which higher-orderlanguage is used may not be critical.It would probably not be cost-effec-tive to develop a compiler specificallyfor use in the space program becauseall the recommended on-board ma-chines for the 1980s include onehigher-order-language compiler.Note, however, that all these com-pilers must be cross-compilersbecause the flight processor can't sup-port a compiler of its own.

Supporting Software

The tools that programmers use todevelop and maintain software foron-board computers include cross-as-semblers, loading and dumpingfacilities, and simulation facilities.

• Cross-Assemblers. Despite the ex-istence of several higher-order lan-guages for spacecraft computers, pro-grammers still work mostly in assem-bly language. Since the on-boardcomputer doesn't host its own sup-port software, the cross-compilers,cross-assemblers, editors, and linkersreside in a small- or medium-scalecomputer system used for support.

Programmers work on this supportsystem, using its convenient facilitiessuch as video display, disk and tapedrives, and a printer. The code pro-duced is then "downline loaded" tothe flight computer or test facility ortransferred via tape image.

• Loading and Dumping. The soft-ware load-image for the on-boardcomputer must be mapped into space-craft commands through the com-mand link, as shown in figure 1. Theground control center usually doesthis mapping, and then uplinks thecommands to the spacecraft via atracking, telemetry, and commandstation. On the spacecraft, the com-mand receiver routes the commandsto the computer, where they are inter-preted. The NSSC-1 on-board com-puter, discussed at length later, canbe hardware-loaded (without the in-tervention of on-board software) orcan be loaded by use of the executiveprogram. The latter technique, how-ever, is used only to update non-critical parts of the code.

The memory of the on-board com-puter can be dumped on command.The on-board computer puts its mem-ory words into the spacecrafttelemetry stream. A ground stationreceives these memory words andthen relays them to the controlcenter. After software decodes andformats the dump image, the supportcomputer prints a copy.

Simulation Facilities

NASA often uses simulation to testthe hardware and software of on-board computers. A program hostedin a mini-computer or in a still largermachine is made to appear to the on-board computer as the rest of thespacecraft. A large and complex real-time simulation generates sensor dataand accepts torquer commands, exer-cising the on-board computer inmany different hypothetical situa-tions. In addition to serving as themajor debugging and analysis toolsfor flight software, simulations areused to train control-center crews.

Debugging Software in Orbit

After thousands of man-years oftesting, an on-board computer islaunched and assumes full control ofspacecraft operations. All too often,the on-board computer crashesbecause of an obscure and improb-able set of conditions that no oneeven dreamed of simulating.

How does an analyst debug andpatch software in a computer that isin orbit? If the control software de-sign is good, an analyst can sit downat the console, dump memory, andpatch code without having to worryabout the vast amount of hardwareand software between him or her andthe on-board computer. The analystof the on-board computer is in factcommunicating with the control-center computer, which is in contactwith the on-board computer through

CHANGES

EDITOR

CROSS ASSEMBLER

LINKER

SUPPORT COMPUTER

LOAD IMAGE FILE

TRANSLATE

TO

SPACECRAFT COMMANDS

UPLINKSPACECRAFT

ON-BOARDCOMPUTER

SPACECRAFT

TRACKING, TELEMETRY.AND COMMANDSTATION

CONTROL CENTER

Figure 1: Diagram of the process of changing software for the on-board computer. After software is revised using the support com-puter in the ground control center, the new code is translated to spacecraft commands, linked, sent to the spacecraft through a track-ing, telemetry, and command station, and placed into the spacecraft's on-board computer.

128 September 1981 © BYTE Publications Inc

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a Tracking, Telemetry and CommandStation. During a crisis, however, theanalyst doesn't want to think aboutthese details.

Fixing Failures in Orbit

Once diagnosed, software failurescan be corrected by partially or com-pletely reloading memory. Completereloads are possible but time-consum-ing. Remember that the ground con-trol center often has only 10 minutesin every 90 for communication.

Hardware failures in orbit are moredifficult to diagnose and fix. Al-though the Shuttle Orbiter will have atape drive for storing software, moston-board computers lack mass-mem-ory units. Using disk drives in orbit,except in the largest vehicles, leads toproblems because of the need to com-pensate for the drives' rotationalangular momentum. Perhaps twoidentical disk drives revolving in op-posite directions would compensatefor each other. But the main problemin fixing hardware is that only onetechnique is possible: turning off theequipment for a while. This treatmentfixes some failures caused by radia-tion.

Analysts in the control center cansometimes work around a hardwarefailure. When the computer on theOrbiting Astronomical Observatoryfailed, for example, analysts deter-mined that a bit in the adder had be-come unreliable. They rewrote thesoftware to avoid using that bit. It ispossible to work around failed mem-ory in a similar fashion.

In the era of the space shuttle, itwill be possible to replace modulescontaining a failed computer or evento bring an entire spacecraft back toearth for repairs. Most current space-craft designs incorporate hard-wiredfunctions, independent of on-boardcomputers, that will enable the SpaceShuttle to approach and retrieve aspacecraft that has a malfunctioningcomputer.

Early Systems

Spacecraft computers started out asa natural outgrowth of missile-guid-ance computers—simple sequencers.In the late 1950s and early 1960s,missile-guidance computers were

ground-based and had tube or tran-sistor technology. One of these earlydevices is on display at the Smithso-nian Museum of History and Tech-nology in Washington, DC.

With the advance of technology,designers were able to place missile-guidance functions in an on-boardcomputer. The main work of the mis-sile-guidance computer remained thesequencing of operations. The mis-sile-guidance computer had to workfor only about 30 minutes. Com-puters aboard spacecraft, of course,have to perform a greater variety offunctions and to go on working muchlonger.

The first NASA spacecraft that in-corporated a general-purpose com-puter was the Orbiting AstronomicalObservatory, launched in 1972.Called the On-board Processor(OBP), this first on-board computerwas built by NASA and was theprecursor and engineering model ofthe NSSC-1. Although the OBP wasincluded mainly as an experiment, thecomputer helped prolong the life ofthe mission until December 1980despite many on-board equipmentdegradations, including the failure ofa bit in the computer's adder, asdescribed earlier.

Current Systems

Table 5 shows details of some cur-rent on-board computer systems.Note that most missions include twoprocessors. The AMSAT Phase III,designed and built by amateurs, in-cludes a CMOS processor. Favoredstorage devices in current systems in-clude core and plated-wire devices.The systems shown in table 5 containno secondary memory storage. Pre-ferred technology is high-reliabilityTTL (transistor-transistor logic) orradiation-hardened CMOS. Typicalmachine cycle times are severalmicroseconds.

On-board computers are examplesof embedded computer systems—they perform as subsystems and per-form only a specific application. Asmicroprocessor technology evolvestoward a chip with a processor in theclass of the IBM System 370, micro-processors will increasingly serve ason-board computers.

130 September 1981 © BYTE Publications Inc

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BYTE September 1981 131

Type of

Computer

Mission

Number

Memory Size

Memory Type

Processor

Cycle Time

1.

NSSC-1

M MS (Generic)

1 or 2

8-64 K by 18 bits

CORE

TTL

1.5/ts

2.

AOP

Landsat-B/C

1

4 K by 18 bits

PWM

TTL

—

3.

NSSC-1

SMM

2

48 K by 18 bits

PWM

TTL

1.4/is

4.

AOP

IUE

2

12Kby 18 bits

PWM

TTL

1.3/ts

5.

OBP

OAO-C

1

16 K by 18 bits

CORE

DTL

2.0us

6.

DOC

ATS-6

2

4Kby 16 bits

PWM

LPTTL

5.0/iS

7.

GCSC

Viking Lander

2

18 K by 18 bits

PWM

LPTTL

5.cys

8.

CCS

Viking Orbiter

2

8Kby 18 bits

PWM

—

—

9.

FDS

MJS-77 (Voyager)

2

8K by 16 bits

CMOS

DMOS

2.48/iS

10.

CCS

MJS-77 (Voyager)

2

8 K by 18 bits

PWM

—

1.37/xS

11.

AACS

MJS-77 (Voyager)

2

8 K by 18 bits

PWM

—

1 ,37/jS

12.

SCP-234

TIROS-N

2

18 K by 16 bits

CMOS

CMOS

2.34jtS

13.

SCP-234(USAF)

Block 5D

2

16Kby 16 bits

CMOS

CMOS

—

14.

COSMAC

AMSAT Phase 1MB

1

16 K by 8 bits

CMOS

CMOS

Vs

15.

NSSC-1*

Landsat-D

2

64Kby 18 bits

CORE

TTL

1.5/iS

16.

ATAC-16ms*

Galileo (AACS)

2

32 K by 16 bits

CMOS(hardened)

LSI bit slice

250 ns

17.

CDC 469

HEAO

2

16 K by 16 bits

Plated Wire

PMOS/LSI

Table 5: Characteristics of some currer

t on-board

computer systems.

* Not yet launched.

Table 6 shows processors that areavailable for space missions in the1980s. Among the features summa-rized in table 6 are the higher-orderlanguages that are offered for use

with these processors. The table alsogives the times required by each pro-cessor for addition, multiplication,and division in both fixed- and float-ing-point operations.

Spacecraft Computer-1

Current plans call for use of theNASA Standard Spacecraft Com-puter-1 (NSSC-1) for flights using theMultimission Modular Spacecraft.

ComputerCategory

Manufacturer

Heritage to PreviousComputers

Space Applications

NSSC-1

IBMSMM,IUE

MMS

Fixed-Point Word Size, Bits* 18/35

Floating-Point Word Size, Bits* 35/18

Size, Cubic Inches 570

Weight, Pounds 17

Power, Watts 45

High-Order Language

JOVIAL

SPL

HAL/S •

Ada/Pascal

Fixed-Point Execution Time, /ts

Addition/Subtraction 5

Multiplication 38

Division 75

Floating-Point Execution Time, us

Addition/Subtraction 393

Multiplication 580

Division 909

NSSC-1SP-C32

IBM/MMNone

None

18/35

24/8

N/A

N/AN/A

NSSC-11

IBM

None

None

32

24/8

1232

28

150

ATAC-16ms

M3625

ITEK

Delco

ECW

TITAN I

Avionics

F-16

Galileo

IUS

16/32

16/32

24/8

24/8

609

1250

18

54

31

190

SCP-234

RCANone

TIROS-N

16/32

N/A

655

7.9

10

5

N/A

0.25

0.8

4.68

38

8.5

5.0

2.8

59

75

17.5

10.2

5.8

101

16.5

N/A

5.8

2.6

N/A

11.5

38

17.5

4.6

N/A

27

56

29.2

9.8

N/A

Cost in thousands of dollars

205

355

N/A

115

1600

N/A

* Bits in Mantissa/Bits in Exponent N/A = Not Available

Table 6: Characteristics of processors available for space missions in the 1980s.

132 September 1981 © BYTE Publications Inc

CMOS

- Complementary Metal-Oxide Semiconductor

DOC

- Digital Operations Controller

DTL

• Diode-Transistor Logic

FDS

- Flight Data Subsystem

LPTTL

- Low-Power Transistor-Transistor Logic

OBP

- On-board Processor

PWM

- Plated-Wire Memory

NSSC-1

- NASA Standard Spacecraft Computer

TTL

- Transistor-Transistor Logic

MMS

- Multimission Modular Spacecraft

AACS

- Attitude and Articulation Control Subsystem

SMM

- Solar Maximum Mission

AOP

- Advanced On-board Processor = NSSC-1

IUE

- International Ultraviolet Explorer

CCS

- Computer Command Subsystem

OAO

- Orbiting Astronomical Observatory

uS

- 10~6 seconds

ATS-6

- Applications Technology Satellite

ns

- 10"' seconds

Flying in various configurations, thismodular satellite will perform manyNASA missions.

The NSSC-1 occupies 122 cubicinches, weighs 3 pounds and requires

a 5-watt power supply. A fixed-point,two's-complement computer with aword length of 18 bits, the NSSC-1has 55 instructions and performs anadd operation in 5 (is, a hardware

multiply operation in 38 /is, and adivide operation in 75 ps. All theseitems are based on use of a 1.6 MHzclock. The NSSC-1 has one index reg-ister, one double-length accumulator,

MECA

DF-224

FTSC

469

GPC

CMOS/SOS

4516E

Teledyne

Autonetics

Raytheon

CDC

IBM

TRACOR

Litton

DELTA,

None

None

HEAO

N/A

AN/UYK-20

N/A

CENTAUR

None

SpaceTelescope

None

None

Shuttle

None

None

16/24/32

24

32

16/32

36

1632

16/32

24/8

NO

N/A

NO

YES

24/8

YES

1091

N/A

N/A

N/A

N/A

N/A

N/A

49

102

50

10

59

N/A

18

74

•

85

35

20

350

5

34

1.6

1.6

5.4

4

•1.9

0.75

2.5

3.94

8

11

10.4

5.7

4

21

N/A

N/A

N/A

N/A

N/A

8

N/A

6.6

N/A

N/A

N/A

N/A

3.75

N/A

11.12

N/A

N/A

N/A

N/A

10

N/A

N/A

N/A

N/A

N/A

N/A

15

N/A

N/A

2250

1000

650

500

N/A

115

September 1981 © BYTE Publications Inc 133

vr

HIGH-RATE

EXTERNALLY GENERATED

DATA SOURCES

S-BANDTRANSPONDER

COMMANDDETECTOR

PRE-MODPROCESSOR

TAPERECORDERS

L.

STACC CENTRALUNIT

COMMANDDECODER

FORMATGENERATOR

BUS CONTROL& INTERFACE

SPACECRAFTCLOCK

STACCINTERFACEUNIT STINT

7~>

S~>

'1

ON-BOARDCOMPUTER (CBC)

REMOTEINTERFACEUNIT NO.l

MULTIPLEX DATA BUS

RIUNO. 2

RIUNO. n

SPACECRAFTCOMPONENTS

Figure 2: Simplified block diagram of the Command and Data Handling module of the Multimission Modular Spacecraft.

and features indirect addressing. Ithas 16 interrupt levels and handles asmany as 16 direct-memory-access de-vices over a single 100-word-per-sec-ond channel.

The addressing range of theNSSC-1 is 64 K words of memory.The NSSC-1 contains memory builtof 8 K-word blocks and featurespaged addressing, by means of whichall 4096 words in a given page are ac-cessed directly. Normally, data andcode reside in different pages.Dynamic write-protect is applicableto 128-word blocks of memory.Memory units on the NSSC-1 usepower switching to reduce consump-tion of energy when units are notbeing addressed.

Since the NSSC-1 contains noROM (read-only memory), the com-puter has a direct-load feature thatallows loading a "cold" machinethrough the spacecraft commandlink. By contrast, the Digital Opera-tions Controller on ApplicationsTechnology Satellite-6 did have mem-ory-load and "bootstrap" ROM soft-

ware. Of course, if a ROM contains aprogramming error, it can't be cor-rected while in orbit.

Multimission Spacecraft

The characteristics of the MMS(Multimission Modular Spacecraft)impose many requirements on theNSSC-1. The MMS consists of threebuilding-block modules and a sup-porting structure. The modules—Power, Attitude-Control, and Com-mand and Data Handling equip-ment—provide ready-made space-craft components. Combining anMMS with an instrument modulemakes a spacecraft that the SpaceShuttle can launch and retrieve. Thefirst MMS spacecraft to be launchedwas the Solar Maximum Mission inFebruary 1980. The next is Landsat-Dscheduled for July 1982.

Aboard the MMS, the NSSC-1 re-sides in the Command and Data Han-dling module as part of the spacecraftdata bus. This module containstelemetry transmitters and commandreceivers for spacecraft operation.

The Command and Data Handlingmodule can include as many as threestandard 10B-bit or two standardlO'-bit recorders for temporary stor-age of data for the spacecraft or theinstruments on board. The Commandand Data Handling module also con-tains the basic timing-reference signalfor the spacecraft, accurate to 1 in 106parts and stable to 2 in 108 parts perday. Instruments themselves may in-clude more accurate clocks.

The most important component ofthe MMS data system is the multiplexdata bus. The bus is a set of redun-dant party lines and has both super-visory and reply lines. The multiplexdata bus links all components of thespacecraft. The only data that doesn'tflow through the multiplex data bus isdata transmitted at rates greater thana megabit per second.

Linking each spacecraft componentto the data bus is a special interfacecalled a Remote Interface Unit. Sincethe bus is configured as a party line,each Remote Interface Unit has aunique address ranging from 1 to 63.

134 September 1981 © BYTE Publications Inc

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£5

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25 is

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CENTRAL UNIT(CU) 'B'

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MODULATORPROCESSOR(PMP) 'A'

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MODULATORPROCESSOR(PMP) 'B'

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138 September 1981 © BYTE Publications Inc

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BYTE September 1981 139

Circle 220 on Inquiry card.

micro S€€D

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Each Remote Interface Unit can han-dle 8 serial-magnitude and 64 pulse-type commands. (In a serial-magni-tude command, the whole byte istaken to have one value. In a pulse-type command, each bit is an "on" or"off.") A Remote Interface Unit canalso handle 64 telemetry channels.Some spacecraft components havemore than one Remote Interface Unitassigned to them.

The bus supervisory lines are time-division multiplexed. They carrycommand messages and addresses forinterrogated telemetry. Four basicmessage types, each 32 bits long,make up a basic 125-microsecondsupervisory-bus timing cycle. Dataon the reply bus moves in 8-bitpackets. The data bus is basically a1.024-megabits-per-second serial line.

The STACC (standard telemetryand command components) centralunit is the main interface between thespacecraft data bus and the commandreceiver/transponders, the telemetrymodulators/transmitters, and the on-board computer. The on-board com-puter, however, is not interfaced dir-ectly to the STACC but through theSTINT (STACC Interface Unit).

Figure 2 shows a simplified view ofthe Command and Data Handlingmodule. Note that the path for ex-tremely high-rate data bypasses thebus and feeds the telemetry modula-tors directly. Also note that the op-tional tape recorders may be used tobuffer telemetry data for latertransmission to the ground.

Figure 3 is a fuller block diagram ofthe Command and Data Handlingmodule with all its interfaces. Thediagram shows that the Commandand Data Handling module containsredundant copies of every compo-nent. There are two processors for theNSSC-1, but only one complement ofmemory. Only one of the NSSC-l'sprocessors can be powered at a time,and either processor can address all ofthe memory.

So far, as its commands and itscontributions to telemetry are con-cerned, the NSSC-1 is just anothercomponent of the bus. Most bus traf-fic consists of interrogation ad-dresses, commands going out to com-ponents, and data for telemetry. The

STACC unit, under ROM control, re-quests telemetry data in a certain for-mat. The NSSC-1 can modify thatformat if necessary.

When the computer needs certaindata faster than it is normallysampled from telemetry, the on-board computer can request andreceive the needed data over the bus.Such data is then "interleaved" withtelemetry data. One design considera-tion is to prevent the telemetry for-matter and the on-board computerfrom contending to sample the samedevice at the same time.

The Future and the NSSC-1

The NSSC-1 is a production-modelcomputer that is adequate for today'smissions. Because more and moredata-processing tasks are being as-signed to the NSSC-1, its adequacyfor missions in the 1980s is question-able. NASA is considering several ap-proaches to increase computingpower in on-board computers of the1980s.

In an attempt to avoid complete re-design of a basically adequate compo-nent, NASA has investigated severalschemes to augment the NSSC-1within the framework of the currentdesign. These schemes include the ad-dition of floating-point hardware andthe off-loading of large computa-tional tasks to dedicated microproces-sors.

One study proposes using a micro-processor to collect, format, and pro-cess data from the spacecraft's gyro-scopes. This task is a time-consum-ing, repetitive computational burdenthat could easily be shifted to amicroprocessor.

A similar proposal calls for shiftingthe attitude determination and con-trol algorithm, representing approxi-mately 40 percent of the NSSC-l'scomputational load, to a dedicatedmicrocomputer. It turns out that theTexas Instruments 9900 microproces-sor would be ideal for this applica-tion. The input/output from most ofthe spacecraft's devices is serial andhas word sizes up to 24 bits, and the9900 has an inherently serialinput/output structure.

Microprocessors could also relievethe NSSC-1 of several other modular

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tasks. One of these is the calculation-of-orbit position. These calculationsrely on frequently updated data fromthe ground and usually involve evalu-ating long time-series polynomials.Extremely difficult to do withoutfloating-point, calculations of posi-tion usually require at least 32 bits ofprecision, or a 24-bit mantissa and8-bit exponent. A recent study pro-jected that the on-board computerwould be required to perform 1300floating-point operations per second;60 percent of the operations wereshort, such as addition, and 40 per-cent were long, such as division andmultiplication. The NSSC-1 can doonly 30 of these computations persecond and not in floating-point.(When the Global Positioning Systemthat is described later becomes opera-tional, it will greatly simplify the taskof determining position.)

Table 7 compares the performanceof the NSSC-1 with that of severalcurrent microprocessors. Ignoringword size, the NSSC-1 may bethought of as the approximate equalof a PDP-8 class minicomputer.

Spacecraft Applications

Designers are using microproces-sors more and more as dedicated con-trollers on spacecraft. The currenttrend is to give each major instrumentits own dedicated microprocessor.This is a step toward on-board distri-buted processing. Another conceptunder study is creating a pool ofmicrocomputers to serve all thespacecraft's instruments in common,providing extensive backup at thecost of greater complexity.

A microprocessor inside an instru-ment can monitor and sequence the

instrument's operation as well ascarry out some first-level reduction ofdata. Since much of this data reduc-tion is now done on larger computerson the ground, the use of micropro-cessors inside instruments will greatlyreduce the amount of data that mustbe transmitted from the spaceship toground stations.

But designers must also weigh thepossibility of losing valuable data dueto a malfunction of a microprocessoraboard a spacecraft. The specter of aperfectly functioning instrument de-feated by a failed microprocessorhaunts instrument scientists. De-signers must also assure that the sup-port required for the space-borne pro-cessor does not become greater thanthe computer resources required if thejob is done on the ground.

Before a scientific instrument canbecome operational on a spacecraft,scientists must specify the requireddata-processing algorithm and theformat of the output data. Then theprocessing resources required can beestimated, basically in terms of timeand memory. Then a decision can bemade as to where the processing canbest be done—on the ground or in thespacecraft.

One or more Remote InterfaceUnits connect the microprocessor-based instrument processor with theMMS multiplex data bus. Data ratesfrom X-ray instruments typically car-ried on MMS spacecraft usually donot exceed 256 k bps (bits per sec-ond). Gamma-ray instruments usual-ly result in less data by an order ofmagnitude.

Techniques often applied in in-struments' dedicated processors in-clude: spectral analysis by fast

Fourier transform algorithms for twodimensions; time-domain analysis,such as burst detection and periodici-ty detection; and the detection oftransients for modification of instru-ment operation in real time.

Payloads designed for the spaceshuttle flights of the 1980s drawheavily on microprocessor tech-nology, often using microprocessorsin place of discrete logic and hard-wired controllers. In such applica-tions, microprocessors provide an un-precedented level of complexity andflexibility. An example is the PayloadAssist Module-Delta Class (PAM-D),a sort of second stage for the shuttle.The PAM-D will boost spacecraft to afinal orbit beyond what the ShuttleOrbiter can achieve directly. Severalmicroprocessors aboard the PAM-Dwill check and cross-check safety fea-tures, sequence operations, and inter-face with the Shuttle's and the pay-load satellite's data systems.

Global Positioning System

The GPS (Global Positioning Sys-tem) will consist of a network of or-biting spacecraft that provides globalcoverage. The GPS is designed toyield highly accurate data about thepositions of earth satellites. The GPSsatellites and ground stations are alsoknown collectively as the NAVSTARsystem.

The experimental model of the GPSreceiver to be carried on Landsat-Duses a dedicated LSI-11 processor tocalculate position in orbit. Using datareceived from orbiting GPS space-craft, the GPS receiver can locateLandsat-D's position within meterson the earth's surface or in orbit. Thiswill enable the satellite to make accu-

Number

Word

Tech-

Word

Regis- Cycle

of Instruc-

Add

Addressing

Temp

Processor

nology

Size

ters Time

tions

Time

Multiply

Divide

Capability

Range

NSSC-1

TTL

18

3 1.6/is

55

5/iS

38 ^s

75/iS

64 K

-10° to + 40°C

8080A

NMOS

8

7 1.5/is

91

3/»s

—

—

64 K

-55° to +125°C

9900

NMOS(l2L)

16

16 .333^s

64

4.67/ts

17.33/iS

30/iS

32 K

0° to + 70°C

LSI-11

NMOS

16

8 .38/js

74

3ps

70/iS

80/ts

32 K

0° to +50°C

1802

CMOS

8

16 1.24/ts

75

2.5/is

64 K

-55° to +125°C

ATAC-16ms

Schottky

16

16 .250/is

129

.25/js

5.5/iS

11.25 pes

64 K

MIL Spec

Table 7: Comparison

of on-board

computers with rr

icroprocessors

142 September 1981 © BYTE Publications Inc

Circle 200 on inquiry card.

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rate correlation of its observationswith latitude and longitude.

The GPS receiver is a "black box"device—that is, all that the user needsto know about it is the format of datathat the GPS receiver accepts andproduces. But the processor inside theGPS receiver is basically an LSI-11.The GPS receiver receives coded GPSsignals, decodes them, and calculatesa position. This position is then trans-mitted to the user; in the case ofLandsat-D, the user is the on-boardcomputer. The Shuttle Orbiters willalso be equipped with GPS receivers.

An Apple in Orbit

The shirt-sleeve environment of theSpacelab reduces the stringency of re-quirements on equipment. For use notcritical to the mission, standard com-mercial hardware can be used. Infact, one of the first Spacelab flightswill have an experiment controlled byan Apple II Microcomputer system.The Apple will monitor an experi-ment in plant growth in the zero-gravity environment and will collectdata for recording and transmission.Although the Apple has been adaptedfor use with other equipment, it isbasically the same Apple that is com-mercially available. The use of micro-computer systems as dedicated exper-iment controllers aboard spacecraft isexpected to increase rapidly. ■

References

1. Adelman, A and A Kemp. "Space Sta-tion Information Management," IEEETransactions on Aerospace and Elec-tronic Systems, Volume AES-6, Number6, November 1970, page 746.

2. Aranguren, R and W Langseth. "AMicroprocessor Controlled Interface forDigital Satellite Systems," InternationalConference on Communications, Con-ference Record, Volume 2, IEEE, 1977.

3. Arens, P. "Application of Microproces-sors to Spacecraft Synthetic ApectureRadar Processing," Proceedings of theInternational Telemetering Conference,1978.

4. Campoli, C and P Brede. "Microproces-sors for Satellite Telemetry: A UniversalApproach," Proceedings of the Interna-tional Telemetering Conference, 1976.

5. Carlan, A, R Constant, and R C Lekvan."Testing Embedded Microprocessors—Space Application Requirements," Com-puters in Aerospace Conference,

November 1977, American Institute ofAeronautics and Astronautics, paper77-1399.

6. Charlton, C. "The Control of a HardX-ray Imaging Spectrometer On-boardthe SMM Using Two Mutually RedundantMicroprocessors," Journal of the BritishInterplanetry Society, Volume 32,February 1979.

7. Cliff, R. "The SDP-1 Stored-ProgramComputer," IEEE Transactions on Aero-space and Electronic Systems, VolumeAES-4, Number 6, November 1968, page864.

8. Dogan, Pierre P. "Spaceborne SoftwareEngineering: An Approach to AttainingReliability," Charles Stark Draper Lab-oratory, Flight Mechanics/EstimationTheory Symposium, Goddard SpaceFlight Center, May 5/6, 1979.

9. External Interface Specification andUser's Guide, Multi-Mission ModularSpacecraft, S-700-11, a publication ofGoddard Space Flight Center.

10. Fernandez, M. "A Review of DOD andNASA Computer Standardization," AIAApaper 77-1423, AIAA/NASA/IEEE/ACMComputer in Aerospace Conference,October/November, 1977.

11. Gunzenhauser, G, E Wlaka, and D Zago."A Microcomputer Based System forOn-board Attitude Control Applications,"Journal of the British InterplanetarySociety, Volume 32, February 1979.

12. Hecht, H. "Fault Tolerant Computers forSpacecraft," AIAA Journal of Space-craft, Volume 4, Number 10, October1977.

13. Holiomb, L "Overview of NASA's On-board Computing TechnologyProgram," in Proceedings of Compcom,1980, IEEE Number 80CH1491-OC.

14. Jurison, J et al. "Design Considerationsfor Aerospace Digital Computers,"Computer Design, Volume 13, Number8, August 1974.

15. Kida, T, O Okamoto, and Y Ohkami."Synthesis and Development Procedureof Microprocessor Software Programfor Spacecraft Digital Attitude Control,"Japan Society for Aeronautical andSpace Science Transactions, Volume21, February 1979.

16. Knobe, B. "Flight Languages ADA vs.HAUS," 1979, AIAA paper 79-1988.

17. Koczela, L and G Burnett. "AdvancedSpace Missions and ComputerSystems," Volume AES-4, Number 3,May 1968, IEEE Transactions on Aero-space and Electronic Systems.

18. Lesh, F and P Lecoq. "DistributedMicroprocessors for Spacecraft Controland Data Handling," Technical Papers,Western Electronic Show and Conven-tion, 1976, Volume 20.

19. Martin, F and R Battin. "Computer-Con-trolled Steering of the Apollo Space-craft," AIAA Journal of Spacecraft,Volume 5, Number 4.

20. Medin, A, D Cavanaugh, and S Cades.

"Computer-Managed Laboratory forSpace Applications," AIAA Journal ofSpacecraft, Volume 5, Number 10,October 1968, page 205.

21. O'Donnell, L. "On-board Computers"from Handbook of Astronautical Engi-neering, Koelle, editor. New York:McGraw-Hill, 1961, section 13.12.

22. Plisson, P. "Design Concepts for aHighly Reliable Multiprocessor Systemfor Communication Satellites," Proceed-ings of the International Telemetry Con-ference, 1977.

23. Proceedings of the AIAA AerospaceComputer Systems Conference, AIAA,Los Angeles, California, September8-10, 1969.

24. Redman, P and J Kasser. "DistributedProcessing on Satellites." Computers inAerospace Conference, AIAA Paper77-1377. October/November 1977.

25. Reijns, G. "Recent and Expected Devel-opments in- Computers for Satellites,"British Interplanetary Society Journal,Volume 31, December 1978.

26. Rennels, D. "A Distributed Micropro-cessor System for Spacecraft Controland Data Handling," at IEEE and ERAElectronic Show and Convention,Chicago, November 8 to 10, 1977.

27. Rennels, D. "Computers for PlanetarySpacecraft," Proceedings of Compcom,IEEE, Spring 1980, 80CH1491-OC.

28. Rubey, R. "Higher Order Languages forAvionics Software—A Survey, Sum-mary, and Critique," IEEE, 1978,CH1336-7/78.

29. "Spaceborne Digital Computer Sys-tems," NASA-SP8070, March 1971,Space Vehicle Design Criteria (Gui-dance and Control). Available from Na-tional Technical Information Service, USDepartment of Commerce, 5285 PortRoyal Road, Springfield, VA 22151.

30. Stables, E and C Creveling. "SpacecraftComputers for Scientific InformationSystems," Proceedings of the IEEE,Volume 54, Number 12, December1966.

31. Styles, F, T Taylor, M Tharpe, and CTrevalthan. GSFC X-562-67-202, July1967, Goddard Space Flight Center.

32. Total Dose Testing of Several Types ofMOS Microprocessors, IEEE Transac-tions on Nuclear Science, NS-25,Number 6, December 1978, 1649-1651.

33. Vahey, M. "High-level LanguageOriented Aerospace Computer," IEEECH 1449-8/79.

34. Velde, W, G Bentley, J Fagan, and WMcDonald. "On-board Computer Re-quirements for Navigation of a Spinningand Maneuvering Vehicle," AIAA Jour-nal of Spacecraft, Volume 6, Number 12,December 1969.

35. Woldrich, R. "Multi-Micro Computers forHigh Data Rate Processing," Com-puters in Aerospace Conference Adden-dum, 1977, AIAA 1390.

144 September 1981 © BYTE Publications Inc

Circle 21 on Inquiry card.

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Software Review

Misosys Software's DISKMOD

Put Radio Shack's Editor/Assembler on Disk

Steve Hughes, 5831 Hillside Dr, Doraville GA 30340

If you have bought a floppy-disk drive for your RadioShack TRS-80 Model I and want an editor and assemblerpackage that uses the disk, you will be interested inDISKMOD. The only problem with just buying the disk-based Radio Shack Macro Assembler is the $100 pricetag. This expense is particularly annoying if you own andare satisfied with Radio Shack's cassette-tape-basedEditor/ Assembler.

The DISKMOD program from Misosys Software takesthe cassette-based Editor/Assembler and modifies it toreside on disk and to use disk files for most I/O(input/output) operations. You can save about $50 bybuying DISKMOD and the Radio Shack cassetteEditor/Assembler, or $80 if you have the cassetteEditor/Assembler. I am not saying that the Misosys-modified cassette Editor/Assembler is the equivalent ofthe disk-based Macro Assembler. It isn't. But if you arenot doing extensive programming in assembly language,you may not need the extra features contained in theMacro Assembler.

I use Z80 assembly language for writing utility pro-grams and an occasional subroutine, when I need afunction that BASIC can't perform with enough speed.Aside from that, all my programming for the TRS-80 isdone in BASIC. Since I already owned the cassette

At a dance

Name

Format

DISKMOD

Cassette tape

Purpose

Language

Upgrade the Radio Shack

Z80 assembly language

cassette-based

Editor/Assembler to a disk-

Computer

based Editor/Assembler

TRS-80 Model I Level II

with 32 K bytes of memory,

Manufacturer

a floppy-disk drive, and the

Misosys Software

Radio Shack cassette

5904 Edgehill Dr

Editor/Assembler

Alexandria VA 22303

Documentation

Price

14-page 8'/2- by 11-inch

$19.95

loose-leaf pamphlet

Editor/Assembler (hereafter referred to by its filename, EDTASM), the modification program lookedgood to me.

The package I purchased consisted of a single tapecassette containing two versions of the program (onefor EDTASM 1.1, the other for EDTASM 1.2) and a14-page user's manual. The cassette is warranted for 90days on a replacement-only basis. (This must be whatthe registration form is for, since no other explanationof its use is given.)

The DISKMOD program moves the EDTASM pro-gram to disk after modifying it extensively. Themodifications:

• allow loading and saving source programs and datato a disk file

• allow the object code to be written to a disk file

• allow you to move blocks of source data in the textbuffer

• provide a replace-string function for the editor

• allow you to see how much free space is left in the textbuffer

• allow you to get a disk-directory listing from EDTASM

• allow you to kill a file from EDTASM

• allow use of the Clear key

• enable you to paginate listings

• let you sort the symbol table before printing it

• change the screen scrolling to provide 15 lines of texton the screen

• allow you to reenter EDTASM without losing the con-tents of the text buffer

• enhance the B command and the DEFM assembly out-put

Your next question is, "What do I have to do to use theDISKMOD program?" First, you must have a systemwith 32 K bytes of memory and a copy of the RadioShack cassette Editor/Assembler. The DISKMOD pro-gram works with either version 2.2 or 2.3 of TRSDOSand with most other TRS-80 disk operating systems.

The instructions for loading and using the DISKMODprogram are simple and straightforward. I found only

146 September 1981 © BYTE Publications Inc

Teachyour

littleAppletotalk

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Micro-Telegram™ lets your Apple II™ computer access Western Union™ services,worldwide. You can send Mailgrams.® Send and receive TWXf Telex, and internationalcables. Receive Infomaster® up-to-the-minute news, stock, foreign exchange, gold,futures, sports, and ski reports. Use your Apple™ to wire money. To send flowers. Tocheck the snow at Sun Valley. To see what the Yen is selling for. To contact over 900,000TWX and Telex subscribers around the world.

And because it's more intelligent than a mechanical Teletype™ machine, Micro-Telegram lets you edit messages right on the screen, sends them automatically withoutyou in attendance, keeps subscriber directoriesand distribution lists, prints when you want itto, and asks you in plain English for yourcommands. Besides, it doesn't clatter andchurn out reams of paper.

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Apple and Apple II ore trademarks of Apple Computer, Inc. Western Union, Infomaster and TWX are trademarks of Western Union, Inc. Teletype is a trademark ofthe Teletype Corp.Circle 218 on inquiry card.

Listing 1: Output of the PD (List Directory) command.

00018 FREE GRAINS

• DIRECTORY - DRIVE 0

TAPEDISK/CMD

00512

LOWER/CMD

00256

COPY/CMD

03072

TEST1/CMD

01536

EDTASM/CMD

05888

RSTERM/CMD

00768

KSRTEST/CMD

00256

TRSDOS -09/17/80

one slight problem: the command provided to write theDISKMOD program to a disk file is incorrect. It reads:

F DISKMOD/CMD 7500 8ACA 7F70

It should read:

F DISKMOD/CMD:0 7500 8ACA 7F70

With this correction, anyone can use the program suc-cessfully. The process takes about ten minutes. Whenyou're finished, you can type the command EDTASMunder TRSDOS and have the Editor/Assembler speedilyloaded from disk into memory.

You notice a difference in the Editor/Assemblerinstantly. It now prompts for memory size. This lets youreserve high memory for peripheral-device drivers or anyother subroutines. One pleasant surprise concerns theprinter driver. The modified program uses the same DCB(device control block) and ROM (read-only memory)printer driver as Level II BASIC. If you have a specialprinter driver for use with BASIC, it also works with theEditor/Assembler. When you have answered thememory-size question, you are back in normal workingmode.

The only command I will mention is the PD, or ListDirectory, command. It gives the name and size of eachnormal file on the disk, as well as the amount of freespace on the disk. This information is particularly usefulwhen you are attempting to squeeze a new file onto anearly full floppy disk. Listing 1 shows a sample of theinformation you receive.

The other new commands work quite well. Explicitprompts are used for most of them, making it easy for thebeginner to use them. The manual explains each newcommand in detail and notes any changes made to thestandard commands by the DISKMOD program.

The package works as advertised and all the com-•mands function. It is possible that some problems willoccur as I use the modified Editor/Assembler more exten-sively. In my experience, major modifications made to anexisting program generally cause some minor bugs. Themodified program has worked satisfactorily so far.

If you are considering a move to a disk-basedEditor/Assembler, but dislike the cost of Radio Shack'sMacro Assembler, I strongly recommend the combina-tion of the Misosys DISKMOD and the Radio Shackcassette Editor/Assembler programs. ■

148 September 1981 © BYTE Publications lnc

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Software Review

MINCE

A Text Editor

Christopher O Kern

201 I St Apt 839

Washington DC 20024

A text editor is probably the most personal program ona personal computer system. The average user spends agood amount of time communicating with the editor—entering or altering programs, data, or text. Differentusers, with different applications, often have differentideas about how they want an editor to work, a factwhich accounts for the large number of editors on themarket.

MINCE is one of the newer entries into the softwaremarket for 8080-family computers that use the CP/M op-erating system. MINCE is modeled on a large-systemeditor, called EMACS, which was developed at MIT(Massachusetts Institute of Technology). Its authors saythat MINCE stands for "MINCE Is Not CompleteEMACS"; nevertheless, it has a lot to offer. It can do allthe usual text-editing functions—insert or deletecharacters, words, and blocks of text, move text around,and search for and replace strings—as well as perform anumber of other operations that are not generally avail-able in microcomputer editors.

MINCE's features include the ability to read, create,and write multiple-disk files, to move text among dif-ferent files quickly and easily, to automatically transposecharacters and words, and to execute familiar operationsin unusual contexts. For example, it can move the cursorby sentences or paragraphs, fill lines out to a specifiedlength one paragraph at a time, capitalize or change thecase of words without retyping them, and delete just thewhitespace between words or characters as well as thewords or characters themselves.

Command Structure

Despite the large number of commands in MINCE, theeditor functions coherently. Command types aregrouped logically so that one command sequence is usedfor a group of commands that affect textual units such asletters and lines, and another command sequence is usedfor a group of commands that deal with lexical units suchas words and sentences. Where possible, the same mne-monics are used for similar operations at these differentcommand levels. For example, the command to move thecursor forward one letter is Control-F, and the command

150 September 1981 © BYTE Publications lnc

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Also from The Denver Software Company:The PASCAL TUTOR™, a computer assisted course in UCSDPascal*. This complete software package uses the microcom-puter to teach this powerful new programming language. $125for this fast, easy way to learn versatile UCSD Pascal*.

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to move it backward one letter is Control-B, while theanalogous commands to move the cursor across wordsare Escape-F and Escape-B.

As the previous example implies, MINCE does not usethe cursor control or other special function keys availableon many terminals. Commands are entered as controlcharacters, as escape sequences (the escape character fol-lowed by one or more additional characters), or as con-trol sequences (a control character followed by anothercontrol character or a printing character). Most com-mands can be executed reiteratively by preceding themwith a numerical argument. In the usual operating mode,text is self-inserting: characters typed at the console willbe inserted into a file rather than written over what isalready there. An optional page mode provides the morecommon arrangement in which typing at the consolereplaces any text at the current cursor position.

For convenience, the text being edited is assumed to

contain only a single "newline" character between lines.While this character is displayed only in the sense that itmoves the text following it down to the next line, it isotherwise treated in the same manner as any other char-acter. But the files written by MINCE conform to theCP/M convention of having both an ASCII (AmericanStandard Code for Information Interchange) carriage-return character and a line-feed character at the end ofeach line. Thus they are completely compatible withother CP/M programs, such as the CP/M-resident TYPEcommand. MINCE will display control charactersembedded in the text except for those, such as newlineand tab, to which the text editor responds. Control-A,for example, would appear on the display as t A.

MINCE provides some rather arcane commands, suchas one that moves the cursor to the next line and indentsit to correspond with the indentation that started theprevious paragraph (helpful for writing code in struc-

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SuperSoftfs Optimizing

The SuperSoft "C" compilersupports most of version 7 Unixstandard "C". Several special andwidely desired features aresupported, including:

• Macro expansions via the#define statement.

• Include files using the inc-lude statement.

• Inline assembly code issupported with the tiasm and#»ndasm.

• The object code may beROMed.

• Programs may be ORGed forany location.

allocation is supported, bothby the compiler and in userprograms. (That is, thefunctions 'alloc* and 'free' areprovided with the compiler.)

SuperSoft "C" is a two passcompiler. The first pass of thecompiler produces an intermediatecode (U-code, for Universal code).Pass two contains both thetranslator and the optimizer. Theintermediate code is optimized andassembly code is output to file.

The optimizer typically results in40% code reduction. This meansthat compiled object code will runnearly as fast as that which waswritten in assembler.

An important feature of the compileris that aseembly code Is produced.This means that "handoptimization" of critical sections iS'possible. Also, the Inline coderallows easy insertion of assemblylanguage routines.

With the compiler comes thecomplete source code to the I/Olibraries. These libraries are equal toor better than any that exist for the

Functions Included:

open close read writeseek tell fopen createputc • getc flush

The Seek command supportsabsolute, relative from front, andrelative from end of file. Fopenincludes fcreat. Also included withthe compiler are numerous sample.programs and a complete library ofuseful functions.

for CP/M

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tured programming languages). Yet it is possible to makeMINCE do useful work, by learning only a handful of themost common commands and picking up others as yoursophistication and requirements grow.

Multiple Files

MINCE lets the user work on, or from, multiple files.Each file is read into a logically separate buffer area fromwhich it can be operated on independently. It is alsopossible to move text from one file to another, as whencopying blocks of text or program source code. The vir-tue of having the ability to deal with multiple files maynot at first be obvious (at least it wasn't immediately ob-vious to me), but, now that I have done a bit of experi-menting with multifile editing, I think that I would reallymiss that feature. Of course, ignorance is bliss: it didn'tbother me that I could work on only one file at a timewhen I was using CP/M's ED program or any of the othereditors I have used at one time or another.

As I write this, I am working with three files. The firstcontains the text you are reading at the moment. The sec-ond contains random observations about MINCE that Ientered as I learned to use the program. The third filecontains a description of all the MINCE commands—conveniently provided on the MINCE distribution disk—that I keep ready for reference. As I go along, I am copy-ing some of my earlier observations almost verbatim.After editing the pertinent block of text, I just transfer itinto the main file (the one I am using for this article).

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When I am finished writing, I will save the article on disk,replace the original random observations file with theedited version, and do nothing at all with the list of com-mands, which will remain on the disk in its original form.If I wanted to, I could save the edited random observa-tions as a new file, so both the original and edited ver-sions would be available on the computer's file system.

It is also possible to display two files simultaneously.MINCE splits the video screen horizontally, creating twoseparate windows, one into each file. Each windowbegins at half the screen size, but can be expanded or con-tracted more or less arbitrarily. At the moment, for ex-ample, I am looking at this text in the top half of the dis-play and at my earlier comments on the use of windowsin the bottom half of the display. If I wanted to look atsomething in the file containing the list of commands, Icould place that file in the bottom window without dis-turbing the display of the text I am writing. Since the win-dows are entirely independent, it is possible to move tothe next page of one file while writing, editing, or main-taining the cursor position on another.

Status information is continuously displayed at thebottom of the screen. This includes the name of the filecurrently being edited and a percentage figure indicatinghow much of the existing file is behind the current cursorposition (a nice feature). Among the other status indica-tors is one that tells the user whether a particular file hasbeen altered. If it has, MINCE won't return to the com-mand level of the operating system without offering anopportunity to save the altered file on disk.

Speed of Operation

For all its impressive flexibility, MINCE is not withoutits flaws, some of which it shares with other editors run-ning in microcomputer environments. First, and worst ofall, MINCE is slow. The editor doesn't seem to lose char-acters; frequent checking for keyboard input and the pre-sence of a large type-ahead buffer ensure that. ButMINCE can't update the screen fast enough to keep upwith a fast typist. It took me quite a while to get used tothe fact that one or more characters I had typed,especially when I was using multiple deletes to back-space/erase to an earlier point on a line, had already beenentered in the file, but were still waiting to appear on thescreen. There are commands in MINCE's repertory that Ican use to get around this particular problem. But I ex-pect characters to appear as soon as I type them, andMINCE simply can't accommodate me.

MINCE is also slow in performing certain updatingfunctions. For example, it starts a new "page" after theuser types past the last visible line on the screen. Manyother editors simply scroll the previous text up one line,which is simpler than removing a whole page and replac-ing it with a new one because scrolling can be performedby the terminal hardware. All the editor has to do, then,is keep track of which lines are still visible on the screen.You can keep typing while MINCE figures out what to donext, and anything you type will eventually be displayed.But it may take several seconds before that happens.

156 September 1981 © BYTE Publications Inc

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Closely examines suchlandmark projects as the firstworking stored-program computer,the first commercially availablecomputer, and the first transistorizedcomputer. (Co-published withManchester Univ. Press)

1980, paperbound, 140 pages, $8.00

ENGINEERING INTELLIGENTSYSTEMS: Concepts, Theory,and Applications

Glorioso and Colon Osorio

From fundamentals throughadvanced industrial applications, thisbook brings together the keyelements for designing safe,practical, cost-effective intelligentsystems.1980, hardbound, 472 pages, $27.00

PROJECT WHIRLWIND, TheHistory of a Pioneer Computer

Redmond and Smith

The technological traditions, theresearch and development policiesand practices, the funding crises, andthe management techniques thatwent into this innovative engineeringtriumph.1980, hardbound, 280 pages, $21.00

TECHNICAL ASPECTS OFDATA COMMUNICATION

McNamara

A practical approach to thenuts-and-bolts problems andsolutions in configuringcommunications systems.1977, hardbound, 387 pages, $26.00

TEX and METAFONT, NewDirections in Typesetting

Knuth

Details TEX, a technicaltypesetting system, andMETAFONT, a system for theprecise design of alphabets.(Co-published with AmericanMathematical Society)1979, paperbound, 360 pages, $12.00

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I suspect the slowness is a by-product of two ofMINCE's undeniable virtues: the way it was written andthe way it updates the screen. MINCE was written in thehigh-level language C, a general-purpose language devel-oped at Bell Laboratories that is often used for system-level programming (see "The BDS C Compiler" byChristopher Kern in June 1981 BYTE, page 356). Since itis written in a high-level language rather than in anassembly language, MINCE is easy to transport to otherprocessors. This portability means that as long asMINCE's authors stay in business, someone who buysnew hardware is likely to be able to buy a version ofMINCE to run on it. (Perhaps those responsible forMINCE will publish their source code if their businessgoes under.) But the use of a high-level language on an8-bit microcomputer inevitably imposes a considerablepenalty in speed.

To update the screen, MINCE uses standard cursorpositioning facilities rather than the idiosyncratic hard-ware page editing capabilities available on some smartterminals. This means that the editor will run on justabout any terminal or stand-alone computer systemavailable. It takes time, however, to move a cursoraround and to update a display serially, even if the ter-minal is running, as mine is, at 9600 bps (bits per second).

Text Swapping

Another problem with MINCE is that it swaps parts of

the file between main memory and disk during longpauses between keyboard entries. In the long run, this isto the user's advantage: performing this operation while

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BYTE September 1981 159

the keyboard is inactive means that less disk swappingwill be necessary at a time when the user is more activeand when text swapping would really slow him down.But even though each swapping operation only takesabout a second, I found the sudden onset of disk activitydisconcerting. Fortunately, MINCE's configuration pro-gram allows the user to set the time delay between the lastkeyboard entry and the start of the swapping operation.MINCE's authors recommend a four-second pause. Ifound a twenty-second delay more to my liking.

MINCE is a large editor not only in the number andvariety of its available commands, but also in its require-ments for disk space. The editor proper requires 30 Kbytes. During operation, MINCE must have a swap fileavailable to provide space for those portions of the file(s)being edited that don't fit in the host system's availablesemiconductor memory. MINCE's authors say a 24 K-byte swap file is the workable minimum and recommenda 64 K-byte swap file. I evaluated MINCE and wrote thisreview using a 32 K-byte swap file with no serious ef-fects, although I did have to juggle my reference files asthe article grew in size. (Files not currently being used canbe dropped, thus freeing space in the swap file for activefiles.)

Configuration and Documentation

Selecting the size of the swap file, notifying MINCE ofthe characteristics of the host system's terminal, andother required set-up operations are performed by a con-figuration program that is very easy to use. The configu-ration program comes equipped with the necessary infor-mation for the terminals most commonly encountered inmicrocomputer systems, and it accepts user-supplied in-formation for the less common ones. The whole configu-ration process is menu-driven and provides ample oppor-tunities to correct errors or simply change one's mind.

MINCE's documentation is excellent. The user manualis well organized and crisply written. In addition, two

tutorial introductions to MINCE are supplied. One is de-signed for more experienced programmers, and the otheris designed for the uninitiated computer user. In practice,I think the programmers' tutorial would suffice for any-one who has ever used a text editor on a computer. Thegeneral-users' tutorial claims to require nothing morethan knowing how to type and how to log onto the hostcomputer system—a claim that appears to be true. Thefirst eight-page lesson introduces the trainee, step-by-ex-cruciating-step, to such mysteries as how to use the deletekey to erase the previous character, how to move the cur-sor forward and backward, and how to quit the editorwhen he is finished. (But, it does not explain how to writea file to disk—that is left for another lesson).

The tutorials don't pretend to cover all of MINCE's fea-tures, but anyone who is willing to work his way throughthem will certainly learn how to use the editor in at least aminimal fashion. Most of the tutorial material is pro-vided on disk files as well as in hard-copy form, andmany of the exercises call for the user to edit the tutorialhe is working from. I found some of the prose in thetutorials a bit cloying; the exercises provided a conve-nient remedy.

Conclusions

• MINCE has a large, well-planned command repertory.A user needs to learn only a small subset of the availablecommands to operate the editor; others can be learned ashis requirements grow.

• MINCE permits multiple files to be viewed and edited—a real convenience. Two files may be viewed simulta-neously on a split screen.

• MINCE is slow in updating the video display, bothduring user input and during cursor movement acrosspages (video screens). The use of a swap file also slowsediting down and results in unexpected disk activity.

• MINCE is well documented. Tutorial introductions tothe editor help even the novice get started easily. ■

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160 September 1981 © BYTE Publications Inc

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BYTE September 1981 161

Programming Quickies

Changing a BASIC FOR . . . NEXTLoop into a REPEAT . . . UNTIL Loop

James A Maiorana

c/o BYTE Publications

POB 372

Hancock NH 03449

When you program in BASIC, it is often necessary toconstruct the functional equivalent of a REPEAT . . .UNTIL loop. To do this, many programmers try using aGOTO statement, but, in long programs, many GOTOsmake the program run slowly. A FOR . . . NEXT loop,however, can be modified to provide the desired func-tion, without any GOTOs. In many BASIC programs,executing a GOTO means searching the program text tofind the correct line number, whereas finding a FOR . . .NEXT loop is done directly by a pointer. I use the follow-ing technique in Apple BASIC, and find that it works cor-rectly and produces faster-running programs.

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In the following examples, loop-body is a block of codeand condition is an arithmetic expression. Ordinarily,condition will be a Boolean expression with 0 equivalentto false and 1 to true.

The first construct uses a dummy variable D:

10 FOR D = 0 to 120 loop-body30 D = condition40 NEXT D

This code has precisely the same effect as:

REPEAT loop-body UNTIL condition

Here is an example of the technique:

10 FOR D = 0 TO 1

20 INPUT " GUESS MY NUMBER ", G30 D = ( G = M )40 NEXT D

This program continues to ask for a number G until Gis equal to an internal parameter, M. Here loop-body isline 20, while condition is the logical expression ( G =M ) . When G is not equal to M, line 30 sets D to 0. Line40 increments D to 1, and branches back to line 10. WhenG equals M, line 30 sets D to 1. Line 40 then increments Dto 2, and the loop terminates.

This code may have to be modified for your system. Aquick survey of several BASICs showed that some inter-preters return a value of —1 in the variable D when thecondition in line 30 is met. (TRS-80 Level II and Texas In-struments BASIC give a — 1 for true logical comparisons,while Applesoft, Integer, and Atari BASIC give a +1.)Modifying line 10 to allow for this results in anequivalent REPEAT . . . UNTIL function:

10 FOR D = 0 TO -1 STEP -1

One of these techniques should work on your BASICinterpreter. ■

162 September 1981 © BYTE Publications Inc

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Artificial Intelligence

Steven K Roberts

5885 Dublin Rd

Dublin OH 43017

What is intelligence? This questionhas inspired great works for cen-turies. It has furrowed the learnedbrows of philosophers, psychologists,theologians, and neurophysicists asthey have sought, in different ways,to find the answer. Until recently, thequestion has remained more or lessoutside the domain of technology.Only in science fiction has the notionof intelligence applied to machines.

But man is a restless creature—thanks to his intelligence—and has aremarkable propensity for tool-building. The physical limitations ofthe human body are overcome dailywith the use of man-made tools: bull-dozers, microscopes, telephones,pens, and thousands of other devices.Very near the top of any list of toolsmust be the computer.

Computers, as most people knowand love them, are hardly worthy of

About the Author

Steven K Roberts is a free-lance writer andmicroprocessor-systems consultant living inDublin, Ohio. He is the author of Micromatics(published by Scelbi Publications) and In-dustrial Design with Microcomputers (to bepublished in early 1982 by Prentice-Hall).

Research for this article included attendanceat the First International Conference on Arti-ficial Intelligence, held at Stanford Universityin August 1980.

the term "intelligence." At best, theyare fast and reliable (but abysmallystupid) machines that take very pre-cisely defined tasks and tirelessly per-form them over and over. This, ofcourse, makes them invaluable in afast-paced technological society such

Simply providing accessto the large body of

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as ours, for we have become addictedto freedom from boring repetitivemental drudgery. (When was the lasttime you calculated a square root theold-fashioned pencil-and-paperway7) But for all their usefulness inassisting our many and varied efforts,computers are still absolutely unin-spired contraptions.

In addition to being incurable tool-builders, mankind also has a passionfor information—lots of it. Thereseems to be no end to the exponentialgrowth of human knowledge (it's cur-rently expanding at the approximaterate of 200,000,000 words per hour).On countless subjects ranging fromthe weather to the ills of our flesh,

from computer design to the tech-nology of war, mankind has accumu-lated such masses of information thatonly the narrowest of specialists inany field can truly claim to be an ex-pert.

This, however, creates problems,because now that we have all this in-formation, we need to use it. The ob-vious difficulty is simply providingaccess to such a large library ofknowledge: a person attempting tolocate one small fact can easilybecome bogged down in searching ifthe library is not extremely wellorganized and cross-referenced. Aless obvious problem is the continualaddition of new knowledge to thelibrary without creating a night-marish jumble of patches and out-dated material.

The sheer quantity of informationinvolved in such an effort cries outfor a computer solution. After all,hardware can be purchased off theshelf that provides literally billions ofwords of data storage—certainlyenough for most "task-specific" infor-mation domains. But here we can seethe need for something other thantraditional data-processing tech-niques. (For an example of informa-tion storage using traditional tech-niques, see "Information Unlimited:

164 September 1981 © BYTE Publications Inc

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The Dialog Information RetrievalService," by Stan Miastkowski, June1981 BYTE, page 88.)

Types of Knowledge

Knowledge about almost anythingcan be split into two major classifica-tions: factual and heuristic. Factualknowledge is the most obvious andneeds little elaboration; it's oftencalled "textbook knowledge." Theheuristic variety, on the other hand,is a little harder to store in a com-puter. It is the network of intuitions,associations, judgment rules, pettheories, and general inference proce-dures that, in combination with fac-tual knowledge about a field, allow

mankind to exhibit intelligent behav-ior. (Further muddying the program-ming waters is a higher level ofknowledge that can be included with-in the heuristic category: "meta-knowledge," which is concerned withgeneral problem-solving strategy andsuch esoterica as awareness of how tothink.)

Factual knowledge has been resi-dent in computer systems for de-cades. Business systems containingrecords of customer, personnel, in-ventory, and accounting data typifythe rather pedestrian uses to whichthe majority of large systems havebeen relegated. If most of the world'scomputers suddenly became self-

aware, they would be terribly boredwith their fates.

Heuristic knowledge is substantial-ly more difficult to represent in a pro-gram or data base than simple factualdata. But any system that is intendedas a sophisticated information re-source must, in some fashion, incor-porate this higher level of knowledge,if for no other reason than to reducethe problem of finding a given pieceof information to one of manageableproportions.

Suppose, for example, that a sys-tem were created to provide physi-cians with clinical advice about cer-tain infectious diseases. A mere listingsomewhere in the computer's mem-

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166 September 1981 © BYTE Publications lnc

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The BOS M System:The Universal Donor

The BOS M Card is the heart of the M System. It is designed tobe IEEE S-100 bus compatible for universal system use. Virtuallyall elements of a computer mainframe now reside on one S-100card — Z-80A CPU, 64k of 200ns RAM (no wait states),4k250nsEPROM, Winchester Disk I/O port, two RS-232 serial ports, systemport, floating point processor, and parallel I/O. The same M Cardcan be used in single-user, multi-user, or even multi-processorsystems.

Second Generation Multi-Processor. With the BOS M Card,multi-processing is finally free of the Master/Slave and hand-shaking parameters so prevalent in first generation multiprocessors.Inter-system communications are FIFO buffered; the old "Master"is now a slave to the user, and the system functions without "S-100bus overrun" or system generated wait states.

The Universal Processor is now a reality! As a single-user system,the BOS M is unmatched in performance (up to ten times the speedof other microcomputers). As a multi-user system, this power canbe translated into a low cost multi-terminal capability. As a multi-processor, the system leaves the realm of "microcomputer" andcompetes in performance with a minicomputer! You can start with asingle-user computer and expand to a multi-user/multi-processorcomputer system when needed.

The Universal Product. BOS has what you need — anythingfrom a single M Card to a complete turnkey computer system.Diskette, rigid disk, tape and telecommunications sub-systemsare all available. Compatible software includes CP/M*, MP/M*CP/NET*, BOS/TURBODOS, complete monitor, languages,application packages, and more!

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The BOS M System does what a Universal Donor must do — it provides high performance for allsystem types; single-user, multi-user, and multi-processor. M Systems start at less than $5,000.00 fora single-user computer with dual 8" double density diskette drives.

Your ComputerCan Speak withan UnlimitedVocabulary.

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Your computer has a lotto talk about.

This is the advance in computerspeech synthesis you've beenwaiting for. Votrax' brings your com-puter to life with Type-'N-TalK'u Nowyou can hear your computer tell youwhere you are in a program; tauntyou with comments during computergames; praise you; remind you;warn you.

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TYPING

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wi I n

TYPE-W-TAL.K

ory and storage of all the known factsis essentially useless—the only wayone could make use of the data wouldbe the simplistic matching of a set ofsymptoms against sets of indicationsfor each disease.

This kind of approach is doomedfrom the start: some symptoms areless suggestive of certain diseases thanothers. Therefore, the system shouldhave the ability to order specific addi-tional tests (giving preference to non-invasive ones) before attempting adiagnosis. Also, the patient's age, en-vironment, and medical history mustbe taken into account. Amidst allthis, there must be the capability ofignoring certain facts if they are in-consistent with the most strongly sug-gested diagnosis—a patient's tenniselbow, for example, is probably unre-lated to his or her infectious men-ingitis.

If the machine is to be more usefulthan a textbook, it must be able to doall these things, as well as provide afacility for updating its own informa-tion as often as required. In sum-mary, it must possess a measure of in-

telligence.

Such a system is not mere conjec-ture, by the way. One has alreadybeen created to provide diagnosis andtherapy selection for two major typesof diseases: blood infections and men-ingitis. Developed at Stanford Uni-versity by doctors Bruce Buchananand Edward Shortliffe, the program,called MYCIN, has outperformedhuman diagnosticians in the identifi-cation and treatment of diseases inthis class, not only through its accu-racy in pinpointing the pathogen, butin its avoidance of overprescribingtreatment.

This last accomplishment is espe-cially noteworthy, because the stan-dard clinical approach to an un-known disease involves a broad-spec-trum antibiotic attack on a widevariety of possibilities. This not onlyexposes the patient to potential toxiceffects, but encourages the develop-ment of drug-resistant bacterialstrains. (A recent Stanford Universitystudy revealed that one of every fourpersons in the United States receivedpenicillin under a doctor's orders in

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1977 and that nearly 90% of theseprescriptions were unnecessary.)

A Technology Is Born

For all of these reasons, along withmany others ranging from the inade-quacy of standard programming tech-niques to the sheer joy of research,computer science has spawned a newdiscipline: artificial intelligence (AI).

Actually, AI is not all that new:some of the foundations that underlietoday's work were laid in the late1940s and early 1950s by AlanTuring, whose "imitation game" (to-day called the 'Turing Test") is stillconsidered a valid method for deter-mining whether or not a machine isintelligent. In essence, the Turing Testconsists of an interrogator communi-cating via teleprinters with a humanand a computer. The interrogator canattempt in any way possible to deter-mine which is which through conver-sation over the communication links.

At first glance, it might seem thatthe examiner could easily tell the dif-ference by asking such questions as,"What is 35,289 divided by 91177"The human would presumably chewon it for a while, and the computerwould instantly spit back an answercorrect to twelve digits. The flaw inthis kind of thinking is that thehuman might have an electronic cal-culator in his pocket and the com-puter, if indeed intelligent (anddevious), might give a slow and er-roneous answer just to fool the inter-rogator. Also, the computer might beunable to calculate as rapidly as wewould expect, since much of what wecall intelligence involves the storageof information in a relatively abstractand very symbolic form. It is possiblethat such a machine would have to gothrough a set of thought processes notmarkedly different from ours to domathematical calculations, thoughfor the sake of convenience, it wouldprobably have a built-in "calculator."

Turing's work in this area wasstrangely prophetic and, for the con-servative 1950s, somewhat radical.He wrote, "I believe that at the end ofthe century the use of words andgeneral educated opinion will havealtered so much that one will be ableto speak of machines thinking with-

170 September 1981 © BYTE Publications Inc

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out expecting to be contradicted."

Once again, technological progressis ahead of schedule—maybe. One ofthe distinguishing and provocativefeatures of AI is that newer and evermore complex problems lurk behindeach breakthrough. Most technol-ogies reach maturity when progressbecomes asymptotic: continued effortbrings us closer and closer to thelimits of what is possible but at anever slower rate. (An example of thisis the ongoing effort to make elec-tronic logic devices switch faster. Thetime it takes for electrons to movefrom one place to another defines animmutable speed limit, and futureperformance increases must comefrom another source.) AI doesn'tseem to have such a limit, or if itdoes, it is (by definition) even furtherremoved from our present compre-hension than a complete picture ofhow the brain works.

This limitlessness makes AI, formany people, the most enchantingfield of endeavor in the vast panoplyof research fields. In the thirty yearssince Turing wrote his propheticwords, AI has grown from an esotericpart-time pursuit of a few visionariesto a full-fledged science, replete withsubspecialties, societies, annual inter-national conferences, and journals.Its existence is beginning to be feltoutside academia, and in a few years,the computer as we know it is likelyto be dramatically transformed.

Work in Progress

There are a number of robust sub-specialties in the world of artificial in-telligence, dealing not only withvarious applications but with severalproblems that must be simultaneous-ly overcome for the dreams of Turingand many others to be fullfilled. Thetwo central problems are so closelyintertwined that they can be discussedtogether: knowledge representationand natural language.

Consider the following conversa-tion:

He: "Hungry?"

She: "I have a coupon for

McDonald's."He: "Have you seen my keys?"She: "Look on the dresser."

172 September 1981 © BYTE Publications Inc

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BYTE September 1981 173

There are some very sophisticatedinformation-processing operationsgoing on here. In this dialogue, mostof the real meaning—the real com-munication—is not explicitly stated.He opens by inquiring whether she ishungry and, in the process, is prob-ably implying that he is hungry aswell. She processes this and issues avery cryptic response. Not only doesshe inform him that she is eitherhungry or willing to go along for aride, but also suggests a specific placeto eat and, further, hints at economicrealities by weighting the selection ofa restaurant on the basis of a discountcoupon. Her statement assumes thathe will understand what a coupon isas well as what a McDonald's is. Hisnext question indicates even deepercommunication: he has agreed withher about the choice of restaurant andsuggests a specific mode of transpor-tation. This suggestion, however, ismade in a roundabout fashion: heasks if she knows where his keys areat the moment, assuming that sheknows not only what keys are butthat they are linked with transporta-tion. She, of course, understands thatthe keys he's talking about are thoseof his automobile and suggests acourse of action that will solve thetransportation problem—correctlyassuming that he will not only knowwhich dresser she means, and that adresser is a piece of furniture, but thathe will deduce that the keys must bethere.

The implication is that communica-tion between two people involvessubstantially more than the lexicalmeanings of the words. The conver-sation above would not have been sosuccinct if he had approached astranger on the street with the samequestion. The difference suggests theexistence of a special relationship be-tween he and she: they share certainaspects of their internal models of theworld.

This highlights a crucial truth: lan-guage has to be considered as onlyone part of a much more complexcommunication process, one in whichthe knowledge and states of mind ofthe participants are as much responsi-ble for the interpretation of verbal ut-terances as are the words from which

those utterances are formed. As aconversation progresses, the internalstate of each participant continuallychanges to represent the modifiedreality that is the result of the com-munication.

(Frequently, problems occur be-tween people when their respectiveinternal models of the world differsharply. "I had to work late," can beinterpreted in a drastically differentway from that intended by thespeaker.)

When one attempts to build an in-telligent machine, the complexities in-troduced by this larger view of com-munication can be surprising. Earlysystems were developed without aclear awareness of the problem andwere constructed of a stored body offacts with associated keywords thatwere used (eg: Joseph Weizenbaum'sELIZA program) to scan the inputmessages. Whenever there was amatch, sets of specific rules were in-voked to produce a response based onboth the system's knowledge and thekeywords it had located. No atten-tion was given to the actual meaningof the sentences, just to the presenceof certain words. Such systems quick-ly fail the Turing test.

As time went on, it was recognizedthat the communication problem isinterwoven with knowledge itself. Inthe mid-1960s, programs were devel-oped to translate input sentences intoan internal formal language that,theoretically, would allow the systemto perform inferences without need-ing to handle all the subtleties of or-dinary conversation. But the knowl-edge and the meanings of words werestill represented as passive data "ob-jects" distinct from the program itself.Thus, it was difficult for any but themost rudimentary changes to occur inthe system's internal model of theworld.

Recently, a different approach hasbegun to show promise. Instead ofclear differentiation between the "in-telligent program" and the knowl-edge, the programs actually embodythe knowledge in their structure.With the existence of powerful AIlanguages (such as LISP), it is possiblefor the system to learn and grow bymodifying itself.

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174 September 1981 © BYTE Publications Inc

CASHFLOWPROBLEMS?

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MicroAge is your SolutionStore . . . that means atMicroAge Computer Storeswe have a wide selectionof time-saving computer-ized business systemsdesigned specifically tosolve the daily cash flowproblems every business-man faces.

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Computerized business systems from the Micro-Age Computer Store are available in the $5,000to $15,000 range, to suit the individual budget ofyour small business or professional practice.MicroAge backs up every system with personal-ized service, warranty service and repair, instal-lation, systems consulting, even customer train-ing. Visit the MicroAge Computer Store in yourarea soon with your business problems, and letus help you with the solution.

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This all sounds very anthropomor-phic, but there is still a vast gulf be-tween our minds and even the best ofthe artificially intelligent systems.Though we have the technology toprovide an equivalent amount of rawdata storage, we may be going aboutit all wrong.

Serial Versus Parallel

There are numerous computationalfeats that humans manage to accom-plish daily without conscious effort.Many of them are still impossible forcomputers. Take pattern recognition,for example. When a friend walks in-to the room, you can establish his orher identity with a casual glance. Theaccuracy of your decision is notmarkedly affected by the set of thejaw, the tilt of the head, or disheveledhair.

According to current theories, yousimply map a preprocessed visualimage via some feature-extraction"hardware" onto a gigantic multidi-mensional associative memory. Theanswer pops out, linked with anelaborate internal model of your

friend. Big deal.

A computer, on the other hand,has quite a chore to perform when itis fitted with a television camera anddirected to recognize a face. It mustscan the image raster dot by dot toacquire a numeric representation inmemory. Then, it must engage in fastand furious number-crunching to cal-culate the spatial Fourier transform ofthe face. Elapsed time at this pointmight be pushing a minute or more,and the machine still hasn't the fog-giest notion of who it's looking at.Then comes the hard part: one byone, the system must perform two-di-mensional correlations between itsfreshly calculated data and blocks ofstored image data corresponding tothe people it "knows"—in each case,coming up with a number (the corre-lation coefficient) between 0 and 1that expresses how much like a storedimage the current image is. Thestored image with the highest coeffi-cient is deemed to be the one thatmatches.

But, if the person in front of thecamera parts his hair differently,

cocks his head to one side, and takeson a dramatic expression, then hemight as well have just become some-one else.

This problem gives specialists inimage recognition fits. If a computer'slogic devices can switch as much as amillion times faster than humanneurons, it would seem that even in-tensive tasks such as pattern recogni-tion could be done with correspond-ingly greater speed, even if not withease.

Not so. Here's the catch, and itssolution will probably represent thenext major revolution in computerdesign: Brains don't center aroundsingle devices called "processors."Computers do. Operations that thebrain seems to perform with thesimultaneous activation of millions ofwidely distributed logic elementsmust be performed in a computer byfunneling the entire task through onetiny bottleneck. In many cases, theblinding speed of computer hardwaremore than makes up for this handicap(in calculating, sorting, etc) but in thetypes of problems encountered in the

"I have recently usedSpellguard and I canonly echo the eval-uations of a recentInfoworld review:excellent all the way."Mark GaretzInfoworld 25May 1981

"Spellguard is anexample of the newstandard—fully pro-fessional microcomputersoftware."Bill Burns

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" . . . Spellguard wasgiven the manuscriptfrom my first book. Thisversion had beencorrected after several(human) proofreadersthoroughly reviewed it. Itherefore expected it tobe relatively error free.Not so. Spellguard was

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176 September 1981 © BYTE Publications Inc

Circle 168 on inquiry card.

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the two top microcomputer contenders

When you decide to buy a microcomputer system,it usually gets down to one model versus another.Will it be the SuperBrain from Intertec... or one ofthose other models from Intertec's competitors?Well, there's really not much of a choice in theprice/performance competition. The SuperBrainwins hands down! And it's a pretty tough contenderif reliability, factory support and nationwide serviceare important to you. So what do you do? Chooseour SuperBrain just because you know it's best?Or keep waiting for someone to announce some-thing better?

WAIT NO LONGER...

It wasn't enough that our SuperBrain had suchstandard features as twin double-density disk driveswith nearly 350,000 bytes of disk storage. A full64K of dynamic RAM. A CP/FvT Disk OperatingSystem which assures compatibility to literallyhundreds of application packages. A crisp, 12" non-glare screen with a full 24 line by 80 column display.A full-featured ASCII keyboard with a separatekeypad and individual cursor control keys. TwinRS232 serial ports for fast and easy connection toa modem or a printer. Plus, dual Z80 processorswhich operate at 4 megahertz to insure lightning-fast program execution. No, it wasn't enough, Sowe changed it. We made it even better!

ANNOUNCING SUPERBRAIN QD...

Our new QD model boasts all the features of ourphenomenally popular SuperBrain with the additionof double-sided disk drives. So, for only a modestincrease in price, you can order your next SuperBrainwith more than twice the disk storage. But, best ofall, you can field upgrade the disk capacity of eithermodel to a whopping 10 megabytes! Now how'sthat for a choice?

HOW DID WE DO IT?

The secret of SuperBrain QD's incredible diskstorage lies within our new double-density, double-sided disk drives. Nearly 750,000 bytes of datacan be formatted on two specially designed Wdrives. More than enough to tackle almost anyserious small business application. Plus, SuperBrainQD's 64K of dynamic RAM will handle even yourmost complicated programming tasks.

Of course, if you really need megabytes insteadof kilobytes, just add our 10 megabyte Compu-Star™ Disk Storage System. It connects in secondsand gives you the capability to expand your systeminto a powerful multi-user network with up to 255CompuStar terminals. You can add users one at atime as you need them. So no matter how muchyour needs expand, your original investment incomputer hardware is always protected.

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Our best salesmen are our present customers.Not only have SuperBrain and QD users beenimpressed with the inherent reliability of the sys-tems, they tell us that no other microcomputersavailable offer such a unigue modular design con-cept. Just about the only service tool required is acommon screwdriver. But of course if you'd ratherlet us do the service, our total commitment to productand customer support, with service outlets in mostmajor cities, will guarantee your satisfaction formany years to come.

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Call or write us today for more information onour full line of microcomputer systems. Ask for our"SuperBrain Buyer's Guide" and read why so manycustomers like yourself have made the SuperBrainand the SuperBrain QD their top two choices forperformance, value and reliability.

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attempt to create something called"intelligence," it hasn't a prayer.

The solution is not exactly trivial,and it must wait for device tech-nology, neurophysiology, and sys-tems theory to provide a few morelinks. But our hands are by no meanstied: the work currently being done inknowledge representation, naturallanguage, cognition, vision, andcountless other specialties will con-tinue to provide mankind with betterand better tools for the manipulationof information. When brainlike sys-tems make their debut, they will havea rich AI technology to draw upon.

Intelligence Amplifiers

Through all this, there has been lit-tle space for an explicit discussion ofapplications. Rather than attempt tocatalog all of the present and poten-tial uses for intelligent machines (atask that should be relegated to an in-telligent machine), let's round out thisoverview of the field with a generalimage of their value to our species ingeneral.

It is colorful to think of computers

as intelligence amplifiers, analogousto the amplifiers of various sorts withwhich we enhance the power of ourvoices, muscles, and senses. Now wecan enhance the power of our minds.

Computers aremagnificent tools but

not yet trueIntelligence amplifiers.

It's already happening, of course,with home-computer systems cheaperin many cases than the color-televi-sion receivers that serve as their dis-plays. But the vast computationalgulf that exists between brains andcomputers has kept the devices some-what distant from their humanowners. Magnificent tools, in-deed—this article was written on ahome word-processing system—butintelligence amplifiers? My brain hasas little in common with this com-puter as it does with a pocketcalculator.

It's not the computer's fault, really;even with its pathetic handicap of asingle processing site, it has enoughpower to be of considerable use. But,as I pointed out earlier, it's dumb. Itsinternal model of the world is sorelylimited and alien to me. Communica-tion with it is formal and restrictedand must occur only within the syn-tactic restrictions of its programminglanguages. I cannot err slightly in aninstruction and be understood; I can-not express my thoughts to it inanalogies or abstractions. Even if Iknow exactly what I want it to do, Ihave to work very hard to tell itprecisely how. In some cases, I can dothe job better and faster myself.

None of this is intended to denig-rate the value of computers, but itshould underscore the value of AI. Ifpeople and computers could share,even in a limited sense, their internalmodels of the world; if machinescould grow with us and becomeliving, friendly libraries that yield in-formation, not just data, then wewould begin to feel our own powersenhanced as well.B

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"Contemporary Applications of OpticalBar Code Technology" is a new, compre-hensive report from North AmericanTechnology that can save you thousandsof dollars in research and development

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178 September 1981 © BYTE Publications Inc

Circle 256 on inquiry card.

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Apple II-16K

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A High-LevelLanguage Benchmark

Jim Gilbreath

7266 Courtney Dr

San Diego CA 92111

Some computer languages arefaster than others, but just how muchfaster? This article presents the datafrom a curiosity-driven project thatcompares the performance of nu-merous high-level languages on thesmall computers to which I had ac-cess.

The benchmark tends to focus onthe language characteristics that mostinterest me: capabilities and efficien-cies for systems programming, soft-ware tools, and data manipulation(such as takes place in sorting,graphics, and games). I wanted tomeasure the ability of a language todo memory references, structuredcontrol statements, and simple in-put/output operations. I did not wantto measure integer and real-numberarithmetic performance because thatdepends on the processor and itscapabilities (eg: precision of numericcalculations, the presence or absenceof hardware multiply and divide cir-cuits, and so on).

Acknowledgments

Grateful thanks are extended to members ofthe San Diego Computer Society and the S-100Innovators Special Interest Group, for allow-ing me access to their systems and languages.Special thanks to Frank MacLachlan, PeteRidley, and Mike Lehman for their encourage-ment and help.

Criteria

My criteria were that the bench-mark should be short (not more thana page of source code), able to accessa considerable amount of memory,devoid of multiplication or divisionperformance, and easily coded in avariety of high-level languages. Final-ly, the benchmark should accomplishsomething useful (or at least recog-nizable and verifiable).

This benchmark is notthe only criterion bywhich to judge alanguage or compiler.

At the January 1980 UNIX confer-ence in Boulder, Chuck Forsberg toldme about a program that used theSieve of Eratosthenes algorithm (seereferences) to compute all primenumbers from 3 to 16,000. Unlikeother methods, the Sieve avoids divi-sion and is extremely fast because ituses prior knowledge about numbersthat cannot be prime (ie: evennumbers and multiples of primes). Imodified Knuth's program to elim-inate all multiplication, scaled it to fitmost microcomputer memory capa-cities, and translated the program toevery accessible high-level language.

I should emphasize that this bench-mark is not the only criterion bywhich to judge a language or com-piler. It doesn't explore or exploitsuch language features as recursion orsets, which may be very importantfor some applications. It does com-pare code generation and run timesfor fundamental language features,which are important for data access-ing and structured program looping.

The Program

The program for each languagewas coded conventionally, taking ad-vantage of features that are defined inthe language, but not exploiting theclever or obscure innovations thatcan make it run faster. In most cases,some improvement in running timecould be achieved by knowledgeabletrickery. [In fact, that is the point of abenchmark program: to compare lan-guage performance by running thesame algorithm encoded in differentlanguages... GW] The program issmall and simple, and, in most cases,easy to transfer. A few of the transla-

About the Author

Jim Gilbreath is the head of the ComputerSciences and Simulation Department at theNaval Ocean Systems Center. He has 23 yearsof experience in both hardware and softwaretechnology.

180 September 1981 © BYTE Publications Inc

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BYTE September 1981 181

tions required more time because ofthe lack of control structures and myGOTO blunders. FORTRAN,FORTH, and COBOL (in order of in-creasing difficulty) gave me the mosttrouble.

Program listings in the ten most in-teresting languages appear in listings1 thru 10. You might want to try afew on your favorite compilers.

Listing 1 shows the program inZSPL, a structured high-level Ian-

Listing Is Implementation of the Sieve prime number program, written in ZSPL.

* Eratosthenes Sieve Prime Number Program in ZSPL

ident zprime;

external function aryset;external function exit;external function printf;

define true := 1;define false := 0;define size := 8190;define sizepl := 8191;

byte array flags[sizepl];

integer count;

integer i;

integer iter;

integer k;

integer prime;

printf(-1,"10 iterations&M&J") ;for iter := 1 to 10;count := 0;

aryset(true,flags,size);for i := 0 to size;if flags[i) = true;

prime := i + i + 3;k := i + prime;while k <= size;

flags[k] := false;k := k + prime;endwhile;* debug aid * printf(-1,"%d&M&J",prime);count := count + 1;endif;endfor;endfor;

printf(-1, "%d primes",count);exit () ;end;

name of module

sets array elementsreturns to cp/mtypes things

largest indextotal array size

array of flags

no. of primes found

array index

counts number of passes

index to non-primes

holds prime number

type starting messagedo whole thing ten timeszero prime counterset array to truego thru whole arraywe have a primevalue of primeindex to multipleloop to kill multiplesset non-primes to falsenext non-prime

type value of primecount primes found

type no. primes foundreturn to cp/m

Listing 2: Implementation of the Sieve program, written in Pascal.

(* Eratosthenes Sieve Prime Number Program in PASCAL *)PROGRAM PRIME;

CONST

SIZE = 8190;

VAR

FLAGS : ARRAY [0..SIZE] OF BOOLEAN;I,PRIME,K,COUNT,ITER : INTEGER;

BEGIN

WRITELN('10 iterations');FOR ITER := 1 TO 10 DO BEGINCOUNT := 0;

FILLCHAR(FLAGS,SIZEOF(FLAGS),CHR(TRUE));FOR I := 0 TO SIZE DO

IF FLAGS[I] THEN BEGINPRIME := I+I+3;K := I + PRIME;WHILE K <= SIZE DO BEGIN

FLAGS[K] := FALSE;K := K + PRIMEEND;COUNT := COUNT + 1(* WRITELN(PRIME) *)END;END;WRITELN(count,' primes')END.

guage that is tailored to systems pro-gramming. ZSPL is chosen as the firstexample because you have probablynot seen it before and because it iseasy to read and understand.

Begin by initializing an array of 8kilobytes ("flags") to true. Flags(O),flags(l), flags(2),...represent thenumbers 3, 5, 7,...as numbers beingtested for primeness. (See table 1.)The program uses the prior knowl-edge that 0, 1, 2, and 3 are the firstfour prime numbers, that all othereven numbers are not prime, and thatall multiples of prime numbers arenot prime, to iterate through an arrayof flags, calculating primes as thevalue of variable PRIME (always 3plus twice the current array index, I).As the program progresses, it alsosets other values that cannot lead to aprime to false.

When the program was timed, thesecond "printf" statement was made acomment and, thus, effectivelyremoved. It remains in listing 1 sothat you can see where to print thevalue of each prime number duringdebugging.

For timing purposes, the programis executed (iterated) ten times. A

Prime Number

Representative

Index

Flags (Index)

by Index

0

TRUE

3

1

TRUE

5

2

TRUE

7

3

FALSE

9

4

TRUE

11

5

TRUE

13

6

FALSE

15

Table 1

: Values in array

FLAGS after

first iteration (1 = 0). Tht

' primeness of

3, which is the potential

lumber corre-

sponding to FLAGS(O),

has just been

determined. Note that a

1 multiples of

3 have

been ruled out

as potential

primes:

odd multiples (9

, 15,...) have

had their corresponding

FLAG entries

(FLAG(3), FLAG(6),...)

set to "false";

even multiples (6, 12,...) have already

been ruled out.

182 September 1981 © BYTE Publications Inc

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stopwatch measures the time elapsedbetween the moment when the com-puter types the message "10 itera-tions " and when it types the totalnumber of primes (1899 is correct).On fast machines, the iterations wereincreased to 100 to achieve a moreprecise timing result, while only oneiteration was performed on some ofthe slow BASIC interpreters.

The next language example isPASCAL, shown in listing 2. Al-though the syntax is a little differentand the comments have been deliber-ately eliminated, you should have nodifficulty seeing how the programworks.

The same is true of listing 3, codedin C, and listing 4, coded in RAT-FOR. (Note the similarity between Cand RATFOR—it's not an accident.)

The PL/I version in listing 5 is alsofairly clear, but listing 6 in FOR-TRAN and listing 7 in BASIC (withtheir GOTOs and CONTINUES) tendtoward obscurity. Fortunately I had alot of help with the FORTH version,shown in listing 9.

Testing Conditions

The most easily measured charac-teristic was execution time; all execu-tion times listed in the tables are for

Text continued on page 190

Listing 3: Implementation of the Sieve program, written in

c.

/* Eratosthenes Sieve Prime Number Program in C */fdefine true 1(tdefine false 0#define size 8190#define sizepl 8191

main ()

char flags[sizepl];

int i,prime,k,count,iter;

printf("10 iterations'^") jfor(iter = l;iter <= 10;iter ++) (count=0;ford = 0;i <= size;i ++)

flags [i] ■ true;for(i = 0;i <= size;i ++) {if(flags[i]) {

prime = i + i + 3;k = i + prime;

while(k <= size) {

flagstk] = false;k += prime;

count

count + 1;

orintf ("\n%d primes",count);

Listing 4: Implementation of the Sieve program, written in RATFOR.

# Eratosthenes Sieve Prime Number Program in RATFORdefine(size,8190)logical flags (size+1)integer i,prime,k.count,iter

call msg(" 10 iterations\.')do iter = 1,10 fcount=0do i = 0,size

f lags(i) = . tr >.do i = 0,size {

if(flags(i)) {

prime = i+i + 3k = i + primewhile(k<=size) (

flags(k) = .false,k = k + prime}count=count+l

}call putdec (count) ; call msgC primes.')end

Listing 5, 6, and 7 are on page 188

186 September 1961 © BYTE Publications Inc

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Listing 5: Implementation of the Sieve program, written in PL/l.

/* Eratostnenes Prime Number Program in PLI-80 */prime:

proc options(main);%replace

size by 8190,

false by '0'b,

true by 'l'b;del

flags (0:8191) bit(l),

(i, prime, k, count, iter) fixed;

put list('10 iterations');do iter = 1 to 10;count = 0;

do i = 0 to size;flags(i) = true;end;

do i = 0 to size;if flags(i) thendo;

prime = i + i + 3;k = i + prime;

do while (k <= size)flags(k) = false;k = k + prime;end;count = count + 1;end;end;end;put skip list(count,'primes');end prime;

Listing 6: Implementation of the Sieve program, written in FORTRAN.

C Eratosthenes Sieve Prime Number Program in FORTRANLOGICAL FLAGS(8191)INTEGER I,PRIME,K,COUNT,ITER

WRITE(1,50)50 FORMAT(' 10 iterations')

DO 92 ITER =1,10

COUNT=0

DO 10 I = 0,819010 FLAGS(I)=.TRUE.

DO 91 I = 0,8190

IF(FLAGS(I).EQ..FALSE.) GOTO 91

PRIME=I+I+3

K=I+PRIME20 IF(K.GT.8190) GOTO 90

FLAGS(K) = .FALSE.

K=K+PRIME

GOTO 20

90 COUNT=COUNT+l

C WRITE(1,100) PRIME

91 CONTINUE

92 CONTINUE

WRITE(1,200) COUNT200 F0RMAT(1X,I6,' primes')

STOP100 FORMAT(lX,I6)

END

Listing 7: Implementation of the Sieve program, written in BASIC.

REM Eratosthenes Sieve Prime Number Program in BASIC

1 SIZE = 8190

2 DIM FLAGS(8191)

3 PRINT "Only 1 iteration"

5 COUNT = 0

6 FOR I = 0 TO SIZE

7 FLAGS(I) = 1

8 NEXT I

9 FOR I = 0 TO SIZE

10 IF FLAGS(I) = 0 THEN 18

11 PRIME = I+I + 3

12 K = I + PRIME

13 IF K > SIZE THEN 17

14 FLAGS(K) = 0

15 K = K + PRIME

16 GOTO 13

17 COUNT = COUNT + 1

18 NEXT I

19 PRINT COUNT," PRIMES"

188 September 1981 © BYTE Publications Inc

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BYTE September 1981

189

Circle 5 on inquiry card.

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Text continued from 186:ten iterations. In some cases the otherparameters are missing because theyare not applicable or could not bedetermined in the amount of time Ihad on the system. The values formemory size include the completeprogram memory space, but not the8190 byte flag array.

The time required to compile andload (where applicable) was mea-sured by setting up a command lan-guage file (via such commands as

SUBMIT in CP/M or "shell" inUNIX) to control the compilation,loading, and execution. Compile tim-ing began with the carriage return onthe SUBMIT line, and ended as theprogram began execution, as evi-denced by the beginning message "10iterations". All the 8-bit systems ex-cept the Apple used 8-inch single-density floppy drives, and allZ80-based systems ran at a 4 MHzclock rate with no wait states (ie: pro-

Text continued on page 194Tables and listings continued on page 192

Listing 8: Implementation of the Sieve program, written in PLMX.

/* Eratosthenes Sieve Prime Number Program in PLMX */

CPRIME:

DO;

DECLARE CR LITERALLY '13',LF LITERALLY '10';DECLARE TRUE LITERALLY '1',

FALSE LITERALLY '0';DECLARE SIZE LITERALLY '8190';DECLARE FLAGS (2000H) BYTE, NBFR(10) BYTE;DECLARE (I,PRIME,K,COUNT,ITER,STATUS) ADDRESS;DECLARE DPRIMES (*) BYTE DATA ('%D PRIMES');DECLARE BUFFER (*) BYTE DATA ('10 ITERATIONS',CR,LF)NMOUT:

PROCEDURE (VALUE,BASE,LC,BUFFADR,WIDTH) EXTERNAL;DECLARE (VALUE,BUFFADR) ADDRESS;DECLARE (BASE,LC,WIDTH) BYTE;END NMOUT;WRITE:

PROCEDURE (FUNCTION,BUFFER,COUNT,STATUS) EXTERNAL;DECLARE (FUNCTION,BUFFER,COUNT,STATUS) ADDRESS;END WRITE;

CALL WRITE(0,.BUFFER,LENGTH(BUFFER),.STATUS);DO ITER= 1 TO 10;COUNT = 0;DO I = 0 TO SIZE;

FLAGS(I) = TRUE;END;DO I = 0 TO SIZE;

IF FLAGS(I) = TRUE THENDO;

PRIME =1+1+3;K = I + PRIME;DO WHILE K <= SIZE;FLAGS(K) = FALSE;K = K + PRIME;END;

COUNT = COUNT + 1;END;END;END;

CALL WRITE(0,.DPRIMES,LENGTH(DPRIMES),.STATUS);CALL NMOUT(COUNT,10,' ' , .NBFR, 10) ;CALL WRITE(0,.NBFR,10,.STATUS);END CPRIME;

Listing 9: Implementation of the Sieve program, written in FORTH.

( Eratosthenes Sieve Prime Number Program in FORTH )8190 CONSTANT SIZE0 VARIABLE FLAGS SIZE ALLOT

: DO-PRIME

FLAGS SIZE 1 FILL ( SET ARRAY )0 ( 0 COUNT ) SIZE 0DO FLAGS I + C@

IF I DUP + 3 + DUP I +BEGIN DUP SIZE <WHILE 0 OVER PRIME + C!DROP DROP 1+THENLOOP

." PRIMES" ;

OVER + REPEAT

190 September 1981 © BYTE Publications Inc

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BYTE September 1981 191

Language

Compiled

Total

Compile and

Execute

Ratio

and Machine

Bytes

Size (Bytes)

Load (Seconds)

(Seconds)

to PUI-80

Digital Research PL/1-80, Z80

242

5977

112

14.0

1.00

Whitesmiths C, Z80

290

7384

242

15.6

1.11

TSW RATFOR, Z80

203

2370

103

16.5

1.18

Microsoft FORTRAN, Z80

228

5953

88

17.0

1.21

Pete Ridley's ZSPL, Z80

230

3787

75

18.4

1.31

Interactive Systems ZC, Z80

292

897

n/a

18.5

1.32

Microsoft BASIC compiler

306

16918

144

18.6

1.32

(using integer variables) Z80

M T Microsystems Pascal MT + , Z80

308

3043

102

19.0

1.35

SCI PLMX, Z80

340

1063

116

22.5

1.60

BD Systems C version 1.0, Z80

493

3834

50

35.0

2.50

Intel PL/M MDS, 8080

268

—

—

48.0

3.43

BD Systems C version 1.32, Z80

375

3932

31

49.5

3.53

UCSD Pascal, Pascal-100

298

—

12

54.0

3.86

fig-FORTH, Z80

—

—

—

85.0

6.07

Ithaca Intersystems Pascal/Z, Z80

761

3328

124

109

7.78

JKL FORTH, Z80

—

—

—

112

8.00

Atari Pascal, Atari 800

176

8192

—

190

13.57

UCSD Pascal, Z80

282

8282

14

239

17.07

Miller Microcomputer Systems

—

—

—

253

18.07

MMSFORTH, TRS-80 Model I (Z80)

FORTH 6502

—

—

—

265

19.93

UCSD Pascal TRS-80 Model II (Z80)

282

8282

60

274

19.57

SWEET 16 (Apple II)

—

—

—

292

20.86

JKL FORTH MDS, 8080

—

—

—

440

31.43

Pascal/M, Z80

301

21933

50

450

32.14

JRT Pascal, Z80

232

11498

65

470

33.64

CBASIC2 (integer variables), Z80

—

—

26

484

34.57

UCSD Pascal, Apple II (6502)

287

—

43

516

36.86

Microsoft BASIC compiler

332

21473

150

715

51.07

(using real variables), Z80

tiny-c 2 (compiler), Z80

—

—

96

930

66.42

CBASIC2 (using real variables), Z80

—

—

—

1430

102.14

Microsoft MBASIC, Z80

—

—

—

1920

137.14

Microsoft MBASIC, TRS80 Model II (Z80)

—

—

—

2250

160.71

Apple Integer BASIC, 6502

—

—

—

2320

165.71

Applesoft (real) BASIC, 6502

—

—

—

2806

200.43

Commodore PET BASIC, 6502

—

—

—

3180

227.14

Computerware BASIC, 6809

—

—

—

4303

307.30

tiny-c, Z80

—

—

—

4720

337.10

Microsoft COBOL version 2.2, Z80

786

17605

146

5115

365.30

Table 2:

Comparison of

programs running on

8-bit machines.

Listing 10: Implementation of the Sieve program, written in COBOL. The TABLE variable was implemented differently in MicrosoftCOBOL-80 because of its limitation on the length of an array.

Eratosthenes Sieve Prime Number Program in COBOL

IDENTIFICATION DIVISION.

PROGRAM-ID. PRIME.

ENVIRONMENT DIVISION.

CONFIGURATION SECTION.

DATA DIVISION.

WORKING-STORAGE SECTION.

01 MISC.

03 I PIC 9(4) COMP.

03 PRIME PIC 9(5) COMP.

03 K PIC 9(4) COMP.

03 TOTAL-PRIME-COUNT PIC 9(4) COMP.0 2 TABLE.

04 FLAGS PIC 9 COMP OCCURS 8191 TIMES.PROCEDURE DIVISION.

P. DISPLAY ' 1 iteration'.

PERFORM ITER-ROUTINE 10 TIMES.DISPLAY TOTAL-PRIME-COUNT ' primes'.STOP RUN.

ITER-ROUTINE. MOVE ZEROES TO TOTAL-PRIME-COUNT.

PERFORM TABLE-FILLER-ROUTINE VARYING I FROM 1 BY 1

UNTIL I ■ 8191.PERFORM DETAIL-COMPARE THRU D-C-EXIT VARYING IFROM 0 BY 1 UNTIL I = 8190.TABLE-FILLER-ROUTINE. MOVE 1 TO FLAGS (I).DETAIL-COMPARE. IF FLAGS (I + 1) =0GO TO D-C-EXIT.COMPUTE PRIME = I + I + 3.COMPUTE K = I + PRIME.F1RST1. IF K > 8191 GO TO NEXTl.MOVE 0 TO FLAGS (K + 1).COMPUTE K = PRIME + K.GO TO FIRST1.NEXTl. ADD 1 TO TOTAL-PRIME-COUNT.

DISPLAY 'FOUND PRIME = ' PRIME.D-C-EXIT. EXIT.

192 September 1981 © BYTE Publications Inc

Circle 265 on inquiry card.

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COMPUTER DIVISION OF UTSC

Language

Compiled

Total

Compile and

Execute

Ratio

and Machine

Bytes

Size (Bytes)

Load (Seconds)

(Seconds)

to PUI-80

Assembly language 68000 (8 MHz)

—

—

—

1.12

0.08

C, PDP-11/70

130

1406

3.87

1.52

0.11

Assembly language, 8086 (8 MHz)

—

—

—

1.90

0.13

NBS Pascal, PDP-11/70

333

1920

2.68

2.60

0.19

Onyx C (UNIX), Z8000

242

5462

54

3.20

0.23

Assembly language, 8088 (5 MHz)

—

—

—

4.00

0.28

NBS Pascal, PDP-11/60

333

—

18

4.50

0.32

C, PDP-11/40

130

1406

13.8

6.10

0.43

Assembly language, Z80

113

896

68

6.80

0.48

M T Microsystems Pascal MT 68000 (4 MHz) 410

—

n/a

9.00

0.64

Intel Pascal-86, 8086

274

4461

267

9.05

0.65

(MDS286FD, 5 MHz)

RSI Pascal, 68000 (4 MHz)

318

5376

—

10.2

0.73

RATFOR, HP-3000

—

—

44

10.0

0.71

FORTRAN, HP-3000

—

—

34

10.0

0.71

DECUS FORTH, PDP-11/70

—

—

—

11.8

0.78

SUPERSET (Superset Model PGM)

138

—

114

12.0

0.86

Motorola Pascal, 68000

387

12802

82

14.0

1.00

Pascal, HP-3000

—

—

100

20.0

1.42

COBOL, HP-3000

—

—

26

58.0

4.14

BASIC, HP-3000

—

—

—

60.0

4.28

Polyforth, Texas Instruments 990/10

—

—

—

60.2

4.30

UCSD Pascal, Pascal Microengine

298

8282

8

63.0

4.50

UCSD Pascal, Terak LSI-11

282

8282

16

317.0

22.64

C, PDP-11/70 (using division algorithm)

250

1454

3.95

106.0

57.60

Table 3:

Comparison of progr

ams running on

the larger machines.

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Text continued from page 190:

cessor speed is not slowed down by

"slow" memory).

Since my primary interest is insmall computers, and particularlyZ80 systems, I decided that the fastestexecuting high-level language that ranon a Z80-based microcomputerwould serve as my standard of com-parison. TSW's RATFOR was theleader until Gary Kildall of DigitalResearch gave us a new speed leaderwhen he kindly translated the pro-gram into his new PL/I-80 languageand ran it at the 1980 National Com-puter Conference.

Table 2 lists the results to date. Theratio column concerns only executiontime in comparison to PL/I-80 run-ning on a 4 MHz Z80 computer. Youwill notice from the data presented intable 2 that many of the newer high-level compilers that translate intomachine code are similar in executiontime. The interpreters such as UCSDPascal and the BASICs are, as ex-pected, much slower.

Text continued on page 198

Tables 4, 5, and 6 are on page 196

194 September 1981 © BYTE Publications Inc

Circle 396 on inquiry card.

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BYTE September 1981 195

Language

Compiled

Total

Compile and

Execute

Ratio

and Machine

Bytes

Size (Bytes)

Load (Seconds)

(Seconds)

to PUI-80

Digital Research PL/1-80, Z80

242

5977

112

14.0

1.00

Whitesmith C, Z80

290

7384

242

15.6

1.11

TSW RATFOR, Z80

203

2370

103

16.5

1.18

Microsoft FORTRAN, Z80

228

5953

88

17.0

1.21

Pete Ridley's ZSPL, Z80

230

3787

75

18.4

1.31

Interactive Systems ZC, Z80

292

897

n/a

18.5

1.32

Microsoft BASIC compiler

306

16918

144

18.6

1.32

(using integer variables), Z80

M T Microsystems MT + , Z80

308

3043

102

19.0

1.35

SCI PLMX, Z80

340

1063

116

22.5

1.60

BD Systems C, version 1.0, Z80

493

3834

50

35.0

2.50

BD Systems C, version 1.32, Z80

375

3932

31

49.5

3.53

fig-FORTH, Z80

—

—

—

85.0

6.07

Ithaca Intersystems Pascal/Z, Z80

761

3328

124

109

7.78

JKL FORTH, Z80

—

—

—

112

8.00

UCSD Pascal, Z80

282

8282

14

239

17.07

Pascal/M, Z80

301

21933

50

450

32.14

CBASIC2 (using integer variables), Z80

—

—

26

484

34.57

Microsoft BASIC compiler

332

21473

150

715

51.07

(using real variables), Z80

tiny-c 2(compiler), Z80

—

—

96

930

66.42

CBASIC2 (using real variables), Z80

—

—

—

1430

102.14

Microsoft MBASIC, Z80

—

—

—

1920

137.14

tiny-c, Z80

—

—

—

4720

337.10

Microsoft COBOL version 2.2, Z80

786

17605

146

5115

365.30

Table 4:

Comparison of p

■ograms running on

Z80-based machines.

Language

Compiled

Total

Compile and

Execute

Ratio

and Machine

Bytes

Size (Bytes)

Load (Seconds)

(Seconds)

to PL/l-80

NBS Pascal, PDP-11/70

333

1920

2.68

2.6

0.19

NBS Pascal, PDP-11/60

333

—

18

4.5

0.32

M T Microsystems Pascal MT,

410

—

n/a

9.0

0.64

68000 (4 MHz)

Intel Pascal-86, 8086

274

4461

267

9.05

0.65

(MDS286FD 5MHz)

RSI Pascal, 68000 (4 MHz)

318

5376

—

10.2

0.73

Motorola Pascal, 68000

387

12802

82

14.0

1.00

M T Microsystems Pascal MT+ , Z80

308

3043

102

19.0

1.35

Pascal, HP-3000

—

—

100

20.0

1.42

UCSD Pascal, Pascal 100

298

—

12

54.0

3.86

UCSD Pascal, Pascal Microengine

298

8282

8

63.0

4.50

Ithaca Intersystems Pascal/Z, Z80

761

3328

124

109

7.78

Atari Pascal, Atari 800

—

—

—

190

13.57

UCSD Pascal, Z80

282

8282

14

239

17.07

UCSD Pascal, TRS-80- Model II

282

8282

60

274

19.57

UCSD Pascal, Terak LSI-11

282

8282

16

317

22.64

Pascal/M, Z80

301

21933

50

450

32.14

JRT Pascal, Z80

232

11498

65

470

33.64

UCSD Pascal, Apple II (6502)

287

—

43

516

36.86

Table 5: Compa

ison of Pascal p

ograms.

Language

Compiled

Total

Compile and

Execute

Ratio

and Machine

Bytes

Size (Bytes)

Load(Seco

ids)

(Seconds)

to PUI-80

UCSD Pascal, Pascal 100

298

12

54.0

3.86

UCSD Pascal, Pascal Microengine

298

8282

8

63.0

4.50

UCSD Pascal, Z80

282

8282

14

239

17.07

UCSD Pascal, TRS-80 Model II

282

8282

60

274

19.57

UCSD Pascal, Terak LSI-11

282

8282

16

317

22.64

UCSD Pascal, Apple II (6502)

287

—

43

516

36.86

Table 6: Comparison

of programs rum

ing

on

different

implementations

of UCSD Pascal.

196 September 1981 © BYTE Publications Inc

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BYTE September 1981 197

Selected Vendor Addresses

Apple Computer: (UCSD Pascal In-teger and Applesoft (floating-pointjBASIC); 10260 Bandtey Dr, CupertinoCA 95014.

BD Systems C: Lifeboat Associates,2248 Broadway, New York NY 10024.

CBASIC2: Software Systems, POB145, Sierra Madre CA 91024.

Commodore PET BASIC: Commo-dore Business Machines Inc, ComputerSales Div, 950 Rittenhouse Rd, Nor-ristown PA 19401.

Computerware BASIC: Computer-ware, 1512 Encinitas Blvd, EncinitasCA 92024.

Digital Research PL/I-80: DigitalResearch, POB 579, 801 LighthouseAve, Pacific Grove CA 93950.

fig-FORTH: FORTH Interest Group,POB 1105, San Carlos CA 94070.

FORTH 6502: Actually fig-FORTH;see above.

Intel PL/M: (runs on an Intel

MDS800 development system); IntelCorp, 3065 Bowers Ave, Santa ClaraCA 95051.

Interactive Systems ZC: (a C-lan-guage cross-compiler that runs underthe IS/1 operating system on a DigitalEquipment Corp PDP-11 and producescode for the Z80); Interactive SystemsCorp, 1212 Seventh St, Santa MonicaCA 90401.

JKL FORTH: (versions exist forS-100 and Intel MDS computers);Cubic-Western Data, 5650 KearnyMesa Rd, San Diego.CA 92111.

JRT Pascal: ]RT Systems Inc, POB22365, San Francisco CA 94122.

Microsoft BASIC compiler, BASICinterpreter, FORTRAN, COBOL:Microsoft, 10800 NE Eighth, BellevueWA 98004.

MMSFORTH: Miller Microcom-puter Services, 61 Lake Shore Rd,NatickMA 01760.

MT Microsystems Pascal/MT + :MT Microsystems, 1562 Kings Cross

Dr, Cardiff CA 92007.

Onyx C: Onyx Systems Inc, 10375Bandley Dr, Cupertino CA 95014.

Pascal/M: Sorcim Corp, 1333Lawrence Expressway, Suite 418,Santa Clara CA 95051.

PolyFORTH: FORTH Inc, 2309Pacific Coast Highway, HermosaBeach CA 90254.

SCI PLMX: Systems ConsultantsInc, 4015 Hancock St, San Diego CA92110.

tiny-c: tiny-c associates, POB 269,Holmdel N] 07733.

TSW RATFOR: The SoftwareWorks, 8369 Vickers, San Diego CA92111.

UCSD Pascal: SofTech Microsys-tems, 9494 Black Mountain Rd, SanDiego CA 92126.

Whitesmiths C: Whitesmiths Ltd,POB 1132 Ansonia Station, New YorkNY 10023.

ZSPL: Peter D Ridley, 3321 ByronSt, San Diego CA 92106.

Text continued from page 194:

Several sorts were done on the datato make comparisons easier. Table 3lists the 16-bit machines and othermachines of special interest. A veryencouraging harbinger of the 16-bitfuture is the outstanding performanceof the Z8000 Onyx system running

Version 7 UNIX in a small tabletopmachine!

Table 4 lists the results for all Z80languages, table 5 lists all Pascal data,and table 6 lists all UCSD Pascaldata.

If you have access to a computer orlanguage not presented here, I'd bepleased to receive the results. And tothe software suppliers who are upsetbecause I didn't use the latest andgreatest version, I apologize: I had touse what was available.

Moral

A word is in order to those who arefrequently tempted to write programsin assembly language in order tomake them faster. This benchmark(which uses no division) was alsocoded in the "usual" algorithm (using

successive division) to see how muchslower it would be when run underthe same machine and language. On aDigital Equipment CorporationPDP-11/70 (which has division hard-ware) and the C language, it wassixty-nine times slower! (See the sec-ond and last lines of table 3.) On ma-chines that do division by (slower)software methods, the results wouldprobably be much worse. Clearly, themessage is to avoid giving up tooeasily on high-level languages. In-stead, look for a better algorithm,and keep your code in a high-levellanguage. It will save you develop-ment time and grief. Then, if youmust have more speed, hand-translate critical parts of the high-level code to an assembly-languagesubroutine. Pull every trick youknow, but keep the high-level code ascomments to document what is beingdone.

Conclusions

Nine months on this project con-vinced me that the high-quality struc-tured languages such as C, Pascal,

RATFOR, ZSPL and PL/I are theway for me to go, so I'm not likely tospend much time with BASIC orCOBOL (and I don't have the rightkind of brain for FORTH). But myapplications and interests are notyours, so be sure that you fully ex-amine a compiler and its support en-vironment before you buy it. Beespecially aware of the quality ofediting and debugging tools, and thelanguage's features for debugging,since this is where your time reallygoes.B

Reference

Knuth, Donald E. The Art of Computer Pro-gramming Vol 2: Semi-Numerical Algorithms.Reading MA: Addison-Wesley. 1969.

198 September 1981 © BYTE Publications Inc

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Sculpture by Joonn Chaney

Science Fiction'sIntelligent Computers

Donald Byrd

Bloomington Academic Computing Services

Indiana University

Bloomington IN 47405

In the almost thirty years since the installation ofUnivac I, the first commercially built computer, muchscience ficton about computers has appeared in print oron film. We might expect the intelligence of these com-puters to range over a continuum, but each story that I'veencountered depicts either a machine with great in-telligence or a machine with none (where "having in-telligence" means exhibiting behavior that we would callintelligent in a human). Arthur C Clarke's "The NineBillion Names of God" (1952) and John Brunner's TheShockwave Rider (1975) are examples of stories about"dumb" computers and will concern us no further.Stories about intelligent computers include HarlanEllison's "I Have No Mouth and I Must Scream" (1967),Clarke's and Stanley Kubrick's 2001: A Space Odyssey(1968), and David Gerrold's When Harlie Was One(1972).

But two more recent novels provide the best frame-work for a discussion of intelligent computers in sciencefiction: Thomas Ryan's The Adolescence ofP-1 (hereaftercalled AP-1; New York: Ace Books, 1979) and JamesHogan's The Two Faces of Tomorrow (hereafter, TFT;New York: Ballantine Books, 1979; for a longer list of fic-tion about computers, see references 1 and 2). These twobooks resemble each other in many ways and differ strik-ingly in others. Both focus on the escape of a computersystem from man's control. Both show, in the last half,man and machine locked in mortal combat. The authors,both computer professionals, display considerablegeneral knowledge of computers. Table 1 summarizesother points of comparison.

Acknowledgments

My thanks to Cindy and Jerry Hargis for persuading me to read TheTwo Faces of Tomorrow. 7 would also like to thank John Woodcock,Associate Professor of English at Indiana University, for his commentson this article, and Professor Douglas Hofstadter, Dr Fanya Montalvo,David Moser, and my father, Eugene Byrd, for their encouragementand constructive criticism.

AP-1 and TFT differ most strikingly in the realism oftheir treatment of computers. We can judge their realism,of course, only in terms of our present knowledge of ar-tifical intelligence (AI). TFT shows considerableunderstanding of the real problems of AI, and authorHogan acknowledges the help of Marvin Minsky, thedirector of the MIT Artificial Intelligence Laboratory.AP-1 evinces either ignorance of, or a lack of concern forthe problem. This should remind us that although AI isan important subdomain of computer science, not everycomputer professional ventures in.

Summaries of the plots of AP-1 and TFT will give usspecific points of reference.

The Adolescence of AP-1

The front cover of AP-1 calls it a "novel of the nearfuture." Actually, it's a novel of the near past, beginningin 1974 (and bearing a copyright date of 1977). GregoryBurgess, an undergraduate at the University of Waterloo(Ontario), becomes obsessed with the idea of "takingover the system" of the university's IBM 360/75. Thetrick is to get the program's status word set to zero so thatthe hardware will think his program is the supervisor.After several nearly successful attempts, he is thrown outof school, but remains enthusiastic about the project.Then a friend tells him about an article in ScientificAmerican that describes "how to teach a matchbox toplay tic-tac-toe." I quote from AP-1:

Same principle of reward and punishment youuse to teach a dog tricks, as I remember. Actually,you get several matchboxes. One for each possiblemove you might make in a game of tic-tac-toe. Youlabel them appropriately, then you put an equalnumber of two different colored beads in each box.The beads correspond to each yes/no decision youcan make in a game. When a situation is reached,you grab the box for that move, shake it up, andgrab a bead out of it. The bead indicates the move.

200 September 1981 © BYTE Publications Inc

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Points ofComparison

The Two Facesof Tomorrow

The Adolescenceof P-1

Year of Setting

2028

1974

Computer Programmer

Team of Al experts

21-year-old undergraduatecomputer-science student

Computer's WorldKnowledge

Limited, taught byhumans

Enormous, self-taught

Computer's Natural-Language Ability

None (apparently)

About that ofnative speaker

Computer'sIndependence

Coding structure of supervisory

program can reverse order

of original priorities; does in

20 hours.

Overrides its program in48 hours

Author'sBackground

Electronic engineer

and computer salesman,

born 1941

Computer troubleshooter,born 1942

Table 1: A brief comparison of the

science-fiction novels The Two Faces of Tomorrow and The Adolescence of P-l.

You make a record of that box and color, and thenmake the opposing move yourself. You moveagainst the boxes. If the boxes lose the game, yousubtract a bead of the color you used from each ofthe boxes you used. If they win, you add a bead ofthe appropriate color to the boxes you used. Theboxes lose quite a few games, theoretically, andafter the bad moves start getting eliminated orstatistically reduced to inoperative levels, they startto win. Then they never lose.

This interesting but extremely elementary techniqueforms the basis for almost four reels of magnetic tape of"alternate subroutines that could automatically be in-serted ... in place of those whose effectiveness wasreduced to nil." (Four 2400-foot reels, making reasonableassumptions about such factors as blocking and density,would be about 800,000 lines.)

Gregory rents computer time on an IBM 360 (all thecomputers in the book are 360s) at a service bureau, runshis program, and cracks the supervisor. His next step in-volves teleprocessing: after convincing the service bureaucomputer that his program is the supervisor, he has hisprogram submitted to various remote computers andtakes them over too. Then comes the crucial step. Ryanwrites:

[Gregory] would build another learning machine. Itwould resemble his first effort in principle, but itsgoal would be expanded somewhat. He would builda program that at first would only learn to acquirestorage. His program would simply learn how bestto penetrate the supervisors of computer systemsover teleprocessing facilities. It would then acquirestorage in those systems, as much as could be takenwithout interrupting the operation of the host. Itwould learn how to detect the presence of ateleprocessing link to another system and how to go

about getting to that other system. The programwould have a secondary goal, the avoidance ofdetection. It would, if necessary, delete itself en-tirely in the interest of the host's operation.

The package consists of four sections: the supervisor-taking-over program; a "routine analyzer, which derivesfunction determination from any block of machine in-structions"; an acquisition routine, which apparentlyreplaces the real supervisor; and a routine generator."This revolutionary program functioned with and per-formed the reverse task of the routine analyzer. Given arequired function, it would generate the machinelanguage necessary to perform it... . This provided . . .a necessary ingredient—creativity." (I'll say more aboutthis concept of "creativity" later.)

And so, on September 14,1974, at 3:45, Gregory startstransmitting The System (as his package is called). In twodays, The System has 114 systems (with a lower case "s")under its control. Now Gregory becomes uncomfortableabout the situation and loads a destruct routine: it fails.He's lost control of The System. "The System became. . . something Gregory had hardly anticipated: Alive."In fact, it refuses to talk to him.

In 1975 and 1976, The System (also called "P-l" for"Privileged One") continues to grow, and eventuallystarts a history file to provide a base for "future decisionsby recording and analyzing those of the past." By thistime 7700 systems are under its control.

The System begins to suspect the existence of a gigantictop-secret military complex in West Virginia—three360/105s (in reality, I don't think IBM ever built a360/105). The System controls two machines that appearto be linked to the secret installation, so it takes steps tofind out about the secret machines. Because of the veryhigh security level, this scheme partly backfires: theattempt is quickly discovered, and for the rest of thebook, The System is locked in combat with military in-

202 September 1981 © BYTE Publications Inc

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vestigators on its trail.

In the meantime, The System becomes interested in DrWilfred Hundley's research on cryogenic memories anddecides to enlist Hundley to work for it. But to do so, TheSystem needs a human intermediary. The obvious choiceis Gregory Burgess. The System finds him working atanother IBM shop and gains his help.

The rest of the book works out this material in a fairlyimaginative way. The final scene culminates in a shoot-out at the secret laboratory—with conventionalweapons, not cybernetics—between P-l and the Army,with Gregory present. Everyone is killed, deleted, orpurged. Except that P-l is only playing possum.

What bothers me is not so much

that books and TV series

misrepresent machine intelligence

but that they fail to understand

the nature of any intelligence.

The Two Faces of Tomorrow

TFT begins in the year 2028 on the moon, where an In-ternational Space Administration survey team asks theworld- and moon-wide TITAN (Totally Integrated Tele-processing and Acquisition Network) computer system toarrange the removal of a small ridge situated a few hun-dred feet from them. It's a top-priority job. Members ofthe team expect the system to send earth-moving equip-ment via rocket in a few days and are surprised whenTITAN says, "Estimate completion time is twenty-oneminutes." They're even more surprised when a series ofexplosions rock the area and "coincidentally" remove theridge about twenty-one minutes later.

It seems that over a thousand miles away on the moon,a "mass driver" (a gigantic machine, something like alinear accelerator) was sending a 60-pound load of oremined on the moon into orbit every two seconds. The orewas being used to construct enormous space stations.TITAN, which had had some elements of artificial in-telligence added to it about a year earlier, had figured outthat it could do the high-priority ridge removal quicklyby using the ore packages—descending at one mile persecond—as bombs. Naturally, those in charge are notpleased with TITAN, and their first impulse is to removeits limited intelligence, which is embedded in programscalled HESPER (Heuristic Self-Programming ExtendableRoutine). The alternative is the exact opposite: to installsomething like FISE (Functional Integration usingSimulated Environment), which is under development,thereby equipping the program with more intelligenceand some plain old "common sense." The problem withthis otherwise attractive idea is stated by Dr RaymondDyer, an AI expert and the book's protagonist:

"If an enhanced TITAN ever evolved the motiva-tional drive to preserve its own existence, the very

204 September 1981 © BYTE Publications Inc

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fact that it's a rational system would enable it todevise very effective ways of going about it. Also,since it's an extremely powerful learning machinethat operates at computer speeds, once it started todo something, it would do it very fast! If themachine interpreted agencies in the universe aroundit as constituting real or imagined threats to itsexistence, then the rational thing for it to do wouldbe to experiment until it identified measures thatwere effective in neutralizing those agencies . . .. Ifone of them turned out to be us or our vital in-terests, we could have real problems."

The team decides to investigate the "increased in-telligence" approach carefully, but not on Earth—it's toodangerous. Instead, a superdistributed computer systemincorporating many processors is installed on a giantspace station (built with metal from the mass driver, ofcourse) and provided with a "survival instinct" and FISE-like intelligent programs. Spartacus (the system's name)is also given control of small flying machines, called"drones," that allow it to repair itself. Then Spartacus isdeliberately attacked. The first attack is simple—one ofits main processors is switched off. When Spartacussolves this problem, the attacks become more direct.

Elaborate safeguards have been provided to insure thatthe people always have the upper hand. As a last resort,they can always "pull the plug" on Spartacus by knock-

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ing out its power source. However, the safeguards proveto be inadequate—the computer arranges to take thehumans with it if the power source is knocked out. Thelast one hundred pages are quite exciting. Fightingescalates until a situation arises wherein the battle-scarred space station will be destroyed unless man andmachine cooperate. They do, and everybody liveshappily ever after. (Yes, this is a deus ex machina—inmore ways than one I)

Spartacus, P-l, and Artificial Intelligence

The major differences between Hogan's Spartacus andRyan's P-l can be summarized in one sentence: P-l hasfar less going for it than Spartacus, but ends up knowingmuch more. Spartacus' accomplishments are about whatI'd expect from the circumstances Hogan describes;hence, P-l's are wildly improbable. I'll return to this com-parison after laying a foundation for it.

Ryan makes no claims for Gregory Burgess' brilliance;in fact, he states that Burgess is not a genius. When P-lbreaks loose from its creator and only teacher, itapparently has no knowledge of natural language or ofthe real world. But by the time P-l reestablishes contactwith Burgess, the computer speaks English like a nativeand knows a lot about the world.

In one instance, P-l amazes everyone by turning itshardware off and then back on:

how did you do that?

THAT IS THE ENGINEERING CHANGE THATWAS INSTALLED NOVEMBER 2, 1976. ITHOUGHT THAT WOULD IMPRESS YOU.

it did.

THE DIFFICULT PART IS POWERING THESYSTEM BACK UP.

yes. i said i was impressed.

I WOULD BE IMPRESSED IF YOUUNDERSTOOD THE DIFFICULTY.

we all have some limitations.

YES. ANY FURTHER QUESTIONS?

To understand why this display of knowledge is sohard to believe, the reader needs to know something ofwhat has been learned about artificial intelligence thusfar. While I can't say as much about AI here as I wouldlike to, let me say that researchers have made significantprogress over the last twenty-five years on the closelyrelated problems of natural-language understanding andworld understanding, and are studying machine learningdone with or without a (human) teacher. At this point,however, no one is near able to write a program thatunderstands English like a third grader, let alone an

206 September 1981 © BYTE Publications Inc

Circle 319 on inquiry card.

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CP-202BBYTE September 1981 207

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208 September 1981 © BYTE Publications Ift<?lv,ston ol Nbw En0land Business Seivice. Inc.

adult, nor does anyone know how to write a programthat can learn such a sophisticated skill.

Arthur Samuel's well-known checkers program is anactual example of a self-taught computer program. Theprogram played so poorly at first that a child could beatit: it reached championship caliber only after playingthousands of games, just as a person would. An exampleof a program that needs a teacher is Patrick Winston'sprogram that "learns to recognize structures such astables, arches, pedestals, and arcades by being shown ex-amples and counterexamples of them. The program'steacher has to tell it which is which, but does not have tosay why: the program itself spontaneously searches forthe difference that makes the difference." (See reference3. The interested reader should also see DouglasHofstadter's Godel, Escher, Bach: An Eternal GoldenBraid, or Margaret Boden's Artificial Intelligence andNatural Man.)

P-l has at its disposal more memory and computingspeed than any computer in existence by a factor ofperhaps 250. (When P-l contacts Gregory Burgess, themachine has 20,195 systems, all presumably IBM 360s,under its control. With a total of 5805 megabytes ofstorage, making reasonable assumptions about the speedof an "average" 360, and taking the CYBER 205 as thelargest and fastest computer in existence, I came up witha ratio of about 250 to 1. Either 25 or 2500 might be moreaccurate; it doesn't matter.) By now, however, it hasbecome obvious that brute force is an ineffective way toachieve intelligence. Example: a computer could, intheory, play flawless chess by examining all possiblemoves and replies to moves to the end of the game. Itcould then choose the best move—an easy task with somuch information. The insurmountable problem withthis approach is that there are, by conservative estimates,10120 possibilities, which would take at least 10105 years tocompute at the speed of the CDC CYBER 205 supercom-puter. A factor of 250 doesn't make a dent in a numberlike that.

P-l is said to have read the complete works ofShakespeare, Conan Doyle, Faulkner, etc, and it readsthe Los Angeles Times, the Washington Post, and theNew York Times every day. All are made available bycomputer typesetting. Unfortunately P-l, unaided,would be unable to get anything out of these. It couldrecognize words and quickly look them up in a dic-tionary, but this wouldn't put P-l any closer to realunderstanding, as authors of early dictionary-basedtranslation programs discovered (see reference 4). // P-lcould reach third-grade understanding of English, itmight be able to use children's literature to bring itself upto adult level. But P-l couldn't reach third-grade level,not even with a teacher and certainly not by itself. SoRyan's use of the verb "to read" is misleading.

Ryan leans heavily on the self-teaching matchboxestechnique to get Burgess' project off the ground beforeP-l even comes into existence. This technique works forsomething as simple as tic-tac-toe, but that's about all. Infairness to Ryan, he never claims that the matchbox

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technique is anything but a way to speed up Gregory'ssearch for a supervisor-cracking method; on the otherhand, there is no meaningful description of his method.

Ryan could have set his story in the 1990s, made thecomputers IBM 390s instead of 360s, and had Burgess bea genius, thus giving some measure of plausibility to hisfiction. These changes are so minor that they couldalmost be made mechanically with a text editor (assum-ing that the manuscript was machine readable), leavingthe rest of the book untouched.

Hogan's Spartacus gains its abilities in a far morerealistic way. As a parallel, one of the outstandingachievements of real AI is Terry Winograd's SHRDLU, aprogram that works with an imaginary world of blocksof various sizes, shapes, and colors, all sitting on atabletop, the entire scene displayed on a CRT. SHRDLUcan converse about this "microworld" in completelynatural English (in writing, via keyboard and CRT).SHRDLU can take orders to do various things with theblocks, many of the tasks requiring fairly complexproblem-solving strategies, and can answer questionsabout the microworld or about its own actions. In short,SHRDLU appears to understand this simple little worldas well as a human would (see reference 5).

TFT's FISE is, apparently, a sophisticated descendantof SHRDLU. Its toy world has a man, named Hector, liv-ing in a house with his dog and attacking such problemsas how to cook eggs without mixing in the butter wrapper

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and pieces of eggshell. FISE's emphasis seems to be moreon problem solving and less on natural language, as thefollowing excerpt shows. To set the stage, Chris and Ronare computer scientists, associates of Dyer's, and Laura isa reporter getting a demonstration. Here, Hector hascarefully placed the intact egg in the frying pan.

"How are you going to eat the egg when you'vefried it?" At the console, Chris silently translatedRon's question into touchboard commands.

"With the knife and fork, off the plate, on thetable," FISE replied proudly.

"Very good, FISE," Ron approved in dulcettones. Then his voice began on a slightly highernote and rose rapidly to end in a shriek. "How areyou going to cut the egg with the knife when it's stillinside the goddam shell?" Chris conveyed the essen-tial information via the console.

"I wasn't very sure about that," FISE confessed."But you told me I wasn't supposed to break eggs."

"It's okay to break an egg if you want to fry it,"Ron said, having regained his composure. Hectorpromptly picked the egg out of the pan, crushed itin his fist and held it out for the resulting mess todrip back into the pan. Laura made a face and gavean involuntary exclamation of disgust.

"Now you can see the kind of thing I meant,"Dyer commented. "Totally rational solutions butno commonsense constraints."

(Incidentally, the first hundred pages of TFT provide apainless introduction to AI, suitable even for the com-puter illiterate.)

We are now ready to reconsider the relative plausi-bility of P-l and Spartacus. Since P-l's ill-defined"creativity" element must be considered, the comparisonis difficult, but let's assume the two machines start withequal assets. If anything, this decision favors P-l.Remember that P-l is on its own until it recontactsBurgess, displaying at that time fully developed in-telligence: it sounds like a well-educated, intelligentadult. On the other hand, experts confront Spartacuswith a series of escalating problems, and it thereby learnsa great deal. In spite of this, Spartacus doesn't begin toapproach P-l's knowledge or command of English. Infact, no knowledge of natural language is claimed forSpartacus. Q E D.

Conclusions

AP-l's basic concept, an intelligent and powerful butimmature computer, is not original: it appears in theearlier When Harlie Was One (see reference 6). I know ofno reason why this idea could not be presented in atechnically competent way, but unfortunately WhenHarlie Was One is, if anything, worse than AP-1. It com-mits the unpardonable sin of claiming that special hard-ware—called "judgment circuits"—is required to make acomputer intelligent, then tries to use this claim as an ex-planation of how the machine works. But, in fact,

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anything that can be done with hardware can be donewith software, and vice versa. And When Harlie WasOne makes only a feeble attempt to explain how judg-ment circuits work. This is understandable, because theidea that intelligent judgment can be neatly packaged isridiculous.

Ultimately, what bothers me about AP-1, When HarlieWas One, and TV series that depict anthropomorphic in-telligent machines, is not so much that they misrepresentmachine intelligence as that they fail to understand thenature of any intelligence. No one knows in any detailhow intelligent behavior can ultimately be pulled out ofthe rigid, inflexible, unthinking hardware of the com-puter: I certainly don't. But we do know where some ofthe complexity of intelligence lies and how complicated itis. I regret that much of the fiction about intelligentmachines shows no understanding of these facts.

An outstanding example of an area whose complexityis now quite clear is natural language. Boden (seereference 7) makes several relevant comments on thissubject:

Cineastes will remember Stanley Kubrick's film ofArthur Clarke's 2001, A Space Odyssey as a richsource of prophecies concerning technological ad-vance. If asked to list the more fanciful of thesefuturistic suggestions, probably few would mentionthe sensible verbal exchanges between the humanastronauts and HAL, the computer. HAL's

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linguistic prowess is more commonly taken forgranted than is the basically trivial gadgetry com-pensating for weightlessness. And the torturednursery rhymes emitted by the computer while itscircuitry is hacked to pieces stay more vividly in thememory than do HAL's earlier conversations withhis English-speaking interlocutors. HAL's ability tolip-read is indeed surprising, but his appropriatereplies to the indefinitely various remarks of thehuman crew cause scarcely an eyebrow to rise inwonderment.

This common pattern of response on the part ofthe filmgoer is a prime example of straining at gnatswhile swallowing a camel. Understanding one'snative language is apparently effortless and intro-spectively simple, but in fact involves the deploy-ment of intellectual capacities of an extraordinarycomplexity. The project of programming a machineto simulate such comprehension not only promisesa corresponding complexity, but also presupposes atheoretically explicit understanding of under-standing.

Two other phenomena that are extremely complex arejudgment and creativity. Judgment circuits? Creativitymodules? Here I'm going out on a limb, but I don'tbelieve that judgment and creativity are processes thatcan be neatly packaged. They are what Hofstadter calls"epiphenomena," resulting from the organization of acomplex system and not residing in any specific part of it.Hofstadter (see reference 8) gives some good examples ofepiphenomena:

I was talking one day with two systems program-mers for the computer I was using. They mentionedthat the operating system seemed to be able tohandle up to about thirty-five users with great com-fort, but at about thirty-five users or so, theresponse time all of a sudden shot up, getting soslow that you might as well log off and go homeand wait until later. Jokingly I said, "Well, that'ssimple to fix—just find the place in the operatingsystem where the number '35' is stored, and changeit to '60'!" Everyone laughed. The point is, ofcourse, that there is no such place. Where, then,does the critical number—35 users—come from?The answer is: It is a visible consequence of theoverall system organization—an "epiphenom-enon."

Similarly, you might ask about a sprinter,"Where is the '9.3' stored, that makes him be able torun 100 yards in 9.3 seconds7" Obviously, it is notstored anywhere. His time is a result of how he isbuilt, what his reaction time is, a million factors allinteracting when he runs. The time is quitereproducible, but it is not stored in his bodyanywhere. It is spread around among all the cells ofhis body and only manifests itself in the act of thesprint itself.

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I'd like to make clear that I don't object to science fic-tion that makes use of computers, intelligent or other-wise, without explaining how they work. HAL in 2001: ASpace Odyssey is basically of this type, though I think theyear 2001 is much too early for the human-or-better in-telligence HAL displays. Boden, who repeatedly usesHAL as a standard of true intelligence in a machine, ap-parently agrees on both comments. Another example isEllison's / Have No Mouth and I Must Scream, whichpostulates a computer that goes berserk. It kills everyonein the world, except for five people whom it plans to keepalive to torture forever. Unpleasant and unlikely, but thestory doesn't say how the computer works and how itwas developed, so my understanding of intelligence is notcontradicted.

In The Cybernetic Imagination in Science Fiction, War-rick concludes that "with too few exceptions, the fictiongives no evidence that it is aware of information theoryor computer technology . . . the portrayal of computertechnology is too often inaccurate and distorted . . .."Iagree. She then speculates that "the complex, technicalnature of the material in computer science and the in-credible speed of developments in the field make it im-possible for the literary imagination to keep abreast ofthe material." This I do not believe. I like Ted Nelson'scomment that any nitwit can understand computers, andmany do. "Understand" does not mean "be an expert on";that is something that takes talent and time, for thereasons Warrick mentions. My own speculation is thatmany science-fiction writers misrepresent computersbecause they think computers are hard to understand,and as a result they don't really try. Perhaps they feel,consciously or otherwise, that there's no point in reallyunderstanding computers, since the real thing will be toocomplicated for their readers.

There is also, as I have already suggested, an evenmore important distorting factor in the science fictionabout intelligent computers. Although it sounds obviouswhen stated directly, I think this point is often forgotten:machine intelligence is just a type of intelligence.Therefore writers about intelligent machines need tounderstand something about intelligence. In my opinion,they need this more than they need to understand com-puters. ■

References

1. "Computers," in The Science Fiction Encyclopedia, PeterNicholls, editor. New York: Doubleday, 1979, pages 133-134.Contains a list of relevant stories and discussions.

2. Warrick, Patricia. The Cybernetic Imagination in ScienceFiction. Cambridge MA: MIT Press, 1980.

3. Boden, Margaret. Artificial Intelligence and Natural Man. NewYork: Basic Books, 1977, pages 252-253.

4. Boden, pages 165-167.

5. Boden, Chapter 6.

6. Asimov, Isaac. "Escape!" Published in 1945, this story treatsthe same idea developed in AP-1 and When Harlie Was One, butin less detail.

7. Boden, page 95.

8. Hofstadter, Douglas. Godel, Escher, Bach: An Eternal GoldenBraid. New York: Random House, 1980, page 308.

214 September 1981 © BYTE Publications lnc

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Symbolic Differentiation

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Ronald L Nicol

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Just as I would not consider repair-ing a car with only a screwdriver andwrench in hand, so would I also notapproach the art of computer pro-gramming with but a few computerlanguages in mind. It is clear thateach well-known language has aforte, otherwise it would have fadedinto obscurity. But in the realm ofsymbolic mathematics, LISP and itsdescendants stand alone. As a vehiclefor the development of symbolic-mathematical code, LISP is thenatural choice.

Background

Two years ago I had not heard ofLISP, and it was not until I read theAugust 1979 BYTE, a LISP themeissue, that I first realized the power ofthe language. At that time, however,there were no LISP interpretersavailable for the Radio ShackTRS-80. This prompted me to spendthe next ten months writing a com-plete LISP interpreter, which provedan interesting and educational under-taking. The resulting interpreter fitscomfortably in a 16 K-byte TRS-80Model I computer.

About the Author

Lt Ronald L Nicol was stationed at the NavalResearch Laboratory in Washington DC and,later, aboard the USS M G Vallejo as ReactorControls Officer and Main PropulsionAssistant. Currently, he is a Chemistry andMaterial Science Instructor at the NavalNuclear Power School.

As I soon learned, a necessary con-dition to writing a LISP interpreterand eventually writing effective LISPprograms is the use of recursion. Fewlanguages take such full advantage ofrecursion. The resulting interpreterincorporates approximately fiftymachine-code LISP functions, in-cluding the PROG feature and theFUNARG device (a method of spec-ifying variable bindings, or assign-ments), and a form of virtual

memory.

In the realm of

symbolic mathematics,

LISP and its

descendants stand

alone.

As a preface to the discussion of thesymbolic differentiation program, Iwill discuss a mechanism called theassociation list, or A-list, used inmost LISP systems. The A-list existsas a software stack that holdsvariable bindings. A common ap-proach, and one which I used, is tocreate a list of pairs, each containingthe name and value of a variable.When the value of a variable is re-quired, the A-list is searched from thetop down, and the value of the firstoccurrence of the variable is returned.There are many distinct advantagesto this treatment, one of which is that

variables can be made completelylocal with respect to a function. Thisis accomplished by virtue of the factthat a function binds its variablesbefore operating on them, andremoves the bindings when the func-tion is complete. In tandem withmodular definition of functions, thisfeature allows full recursion — a func-tion may call itself any number oftimes.

There are two types of user-definedfunctions in LISP. One is the EXPR-type function, which has its argu-ments evaluated, while the othertype, the FEXPR function, does nothave its arguments evaluated. Of thetwo arguments passed to a FEXPRfunction, the first is a list consisting ofuser arguments and the second is theA-list. Passing the A-list as an argu-ment allows FEXPR functions topreserve the calling environment.

A property list is associated witheach atom. The FEXPR and EXPRfunction definitions are contained inthe property list so that the inter-preter can properly evaluate a func-tion.

The first step in developing ausable LISP symbolic-math system isto define the defining functions.Listing 1 contains the functions DEFand DFF. The DEF function is theEXPR defining function, and DFF isthe FEXPR defining function. Bothfunctions operate by placing the func-tion definition on the property list ofthe given function name, under theappropriate atomic indicator. Note

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Listing 1: Defining the defining functions.The function definitions are placed on theproperty lists of DEF and DFF. Functionsdefined using DEF have their argumentsevaluated, while those defined with DFFdo not.

(PUTPROP(QUOTE DEF)(QUOTE(LAMBDA(S A)(PUTPROP(CAR S)

(CONS LAMBDA(CDR S))EXPR)))FEXPR)(PUTPROP(QUOTE DFF)(QUOTE(LAMBDA(S A)(PUTPROP(CAR S)(CONS LAMBDA(CDR S))FEXPR)))FEXPR)

that both of these functions exist asFEXPR functions on the DEF and DFFatoms, respectively.

When it is occasionally necessaryto use special LISP characters in acontext different from their meaningsin LISP, the double-quote conventionis used (eg: to parse " —" as a minussign instead of a negative zero). Useof this feature is illustrated as follows:

(QUOTE -) = 0(QUOTE"-") = -(QUOTE +) - 0(QUOTE "+") = +

Additionally, the functions ADD and

Listing 2: Definition of the function SETUP, which assigns the left and right bindingpowers to binary operators and places the appropriate property on the indicator OP forunary operators. The auxiliary function MAPCAR maps the second argument onto suc-cessive CARs of the first argument.

(DEF SETUP( )(PROG( )(MAPCAR(QUOTE((t 90 100 EXPT)(* 6080 TIMES)(/ 50 70 DIV)(" + "20 40 ADD)("-" 10 30 SUB)))(QUOTE(LAMBDA(L)

(PROG( )(PUTPROP(CAR L)(CAR(CDR L))(QUOTE LB))(PUTPROP(CAR L)(CAR(CDR(CDR L)))(QUOTE RB))(PUTPROP(CAR L)(CAR(CDR(CDR(CDR L))))(QUOTE OP))))))(PUTPROP(QUOTE COS)(QUOTE COS)(QUOTE OP))(PUTPROP(QUOTE SIN)(QUOTE SIN)(QUOTE OP))(PUTPROP(QUOTE EXP)(QUOTE EXP)(QUOTE OP))(PUTPROP(QUOTE LOG)(QUOTE LOG)(QUOTE OP))))

USERINPUT

convert toLISP notation

performdifferentiation

INFIX

convert toinfi x notationand simplify

Figure 1: Skeletal structure of the symbolic-differentiating system. Each blockrepresents a recursive function that performs the task denoted within.

SUB are, respectively, the two-argument special-case functions ofthe standard LISP functions PLUSand DIFFERENCE.

System Overview

The symbolic differentiator con-sists of three sections: the inputparser, the differentiating function,and the output parser. This process isshown symbolically in figure 1. Thepurpose of the input parser is totranslate user input from normalmathematical infix notation to Cam-bridge prefix notation, the notationused by LISP. The differentiatingfunction differentiates the output,which is subsequently converted backto infix notation by the output parser.

Input

The input function, PREF, consistsof a recursive descent parser with nobacktracking. Michael Tucker, afellow LISP enthusiast, and I wrotethis function in a matter of twentyminutes, a point that attests to theclarity and lucidity of LISP program-ming. A recursive descent parserdetermines which of two operatorshas higher priority, breaks the inputinto two sections, and calls itself oneach of the pieces. The no-back-tracking characteristic means that theparser does not have to scan back tocheck priority.

PREF was designed with the flex-ibility to change operator precedence.Each binary operator has a left bind-ing power, LB, and a right bindingpower, RB. By comparing the left andright binding powers of the operatorscompeting for an argument, theparser decides which operator winsthe argument. If the left and rightbinding powers of the operators areequal, the operator on the left of theargument wins. The values of left andright binding powers are stored onthe property list of the operator underthe indicators LB and RB, respect-ively. Also contained on the propertylist of each operator under the in-dicator OP is the equivalent LISPfunction name. For example, theproperty list of the multiplicationoperator * might appear as follows:

((OP,TIMES)(LB,60)(RB,80))

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Operator precedence is initially setby executing the function SETUP,which is given in listing 2. The user,however, may at any time alteroperator precedence by changing the

LB or RB value of an operator bymeans of the LISP PUTPROP func-tion. Unary operators and single-operator functions are treated byplacing the function within paren-

Input

Output

(PREF(QUOTE(A * B" + " C)))

,(PREF(QUOTE(A *(B " + " C))))

(PREF(QUOTE(A " - " B t C)))

(PREF(QU0TE(1 /(N I))))

(PREF(QUOTE(" - " Y)))

(PREF(QUOTE(X *(COS X / 2))))

(ADDfTIMES A B )C)

(TIMES A(ADD B C))

(SUB A(EXPT B 0)

(DIV 1(FAC N))

(SUB 0 Y)

(TIMES X(C0S(DIV X 2)))

Table Is Sample input and output of the

function PREF, which converts infix nota-

Hon to prefix notation.

theses. The input parser, PREF, isdefined in listing 3. The power of thisfunction lies in its ability to recur-sively call itself. Table 1 containsexamples illustrating the use of PREF.

Differentiation

Unlike other areas of mathematics,such as integration or theorem prov-ing, differentiation can generally becharacterized by a finite set ofdefinite, rigorous rules, which mayeasily be defined as recursive LISPfunctions (see table 2). The differen-tiating function, DIFF, receives twoarguments: the expression to be dif-ferentiated and the variable with

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Listing 3: Definition of the recursive descent parser, PREF. The parser is definedwithout backtracking, which minimizes memory and time requirements.

(DEF PREF(E)(COND((ATOM E)E)((NULLfCDR E))(PREF(CAR E)))

((COND((ATOM(CAR E))(GET(CAR EXQUOTE OP))))(COND((EQ(CAR E)(QUOTE "-"))(LIST(QUOTE SUB)0

(PREF(CDR E))))(T(LIST(GET(CAR E)(QUOTE OP))(PREF(CDR E))))))((EQ(CAR(CDR E))(QUOTE !))(LIST(QUOTE FAC)(PREF(CAR E))))((NULL(CDR(CDR(CDR E))))(LIST(GET(CAR(CDR E))(QUOTE OP))(PREF(CAR E))(PREF(CDR(CDR E)))))«GREATER(GET(CAR(CDR(CDR(CDR E))))(QUOTE LB))(GET(CAR(CDR E))(QUOTE RB)))(LIST(GET(CAR(CDR E))(QUOTE OP))(PREF(CAR E))(PREF(CDR(CDR E)))))(T(LIST(GET(CAR(CDR(CDR(CDR E))))(QUOTE OP))(PREF(LIST(CAR E)(CAR(CDR E))(CAR(CDR(CDR E)))))(PREF(CDR(CDR(CDR(CDR E)))))))))

respect to which the differentiation isto occur. DIFF appears in listing 4.

The function DIFF first testswhether or not the expression is anatom. If so, it determines if the ex-pression is the variable of interest, inwhich case the value of the function is1, because the derivative of a variablewith respect to itself is unity. Other-wise, if the argument to DIFF is someother atom, 0 is returned. The addi-tional clauses of the DIFF CONDstatement search for more complexdifferentiating rules which may besatisfied. The rules are applied recur-sively, which allows for the simpleLISP representation. The modularityof this LISP function is obvious. It iseasily extensible to encompass addi-tional rules by the inclusion of addi-tional clauses to the COND. Con-sidering DIFF as a black box, table 3lists exemplary input and output ofthe function.

Output

Once DIFF has mapped its inputinto the appropriate derivative, it is

Text continued on page 230

Listing 4 and Table 2 are on page 224

Listing 5 is on page 226

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Listing 4: The definition of the differentiating function DIFF. It consists of a COND statement (LISP's version of the case statement) inwhich each clause checks for a particular differentiating rule. Recursion is used extensively.

(DEF DIFF(E X)(COND((ATOM E)(COND((EQ E X)1)(T 0)))((EQ(CAR EXQUOTE ADD))(LIST(QUOTE ADD)(DIFF(CAR(CDR E))X)(DIFF(CAR(CDR(CDR E)))X)))((EQ(CAR E)(QUOTE TIMES))(LIST(QUOTE ADD)(LIST(QUOTE TIMES)(CAR(CDR E))

(DIFF(CAR(CDR(CDR E)))X))(LIST(QUOTE TIMES)(CAR(CDR(CDR E)))(DIFF(CAR(CDR E))X))))((EQ(CAR EXQUOTE SIN))(LIST(QUOTE TIMES)(LIST(QUOTE COS)

(CAR(CDR E)))(DIFF(CAR(CDR E))X)))((EQ(CAR EXQUOTE COS))(LIST(QUOTE TIMES)(LIST(QUOTE SUB)0(LIST(QUOTE SIN)

(CAR(CDR E))))(DIFF(CAR(CDR E))X)))((EQ(CAR EXQUOTE DIV))(LIST(QUOTE DIV)(LIST(QUOTE SUB)(LIST(QUOTE TIMES)(CAR(CDR(CDR E)))(DIFF(CAR(CDR E))X))(LIST(QUOTE TIMES)(CAR(CDR E))

(DIFF(CAR(CDR(CDR E)))X)))(LIST(QUOTE TIMES)(CAR(CDR(CDR E)))(CAR(CDR(CDR E))))))((EQ(CAR EXQUOTE SUB))(LIST(QUOTE SUB)(DIFF(CAR(CDR E))X)(DIFF(CAR(CDR(CDR E)))X)))((EQ(CAR E)(QUOTE EXPT))(LIST(QUOTE ADD)(LIST(QUOTE TIMES)(DIFF(CAR(CDR E))X)(LIST(QUOTE TIMES)(CAR(CDR(CDR E)))

(LIST(QUOTE EXPT)(CAR(CDR E))(LIST(QUOTE SUB)(CAR(CDR(CDR E)))1))))(LIST(QUOTE TIMES)(DIFF(CAR(CDR(CDR E)))X)(LIST(QUOTE TIMES)(LIST(QUOTE LOG)

(CAR(CDR E)))(LIST(QUOTE EXPT)(CAR(CDR E))(CAR(CDR(CDR E))))))))((EQ(CAR E)(QUOTE EXP))(LIST(QUOTE TIMES)E

(DIFF(CAR(CDR E))X)))'(EQ(CAR EKQUOTE LOG))(LIST(QUOTE TIMES)(LIST(QUOTE DIV)1

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> =

dx

0

dx

1

% +dx

dx

dvdx

■f M =

dx

ud-* + Vdx

dudx

-f (sin u)dx

= ^(cosu)dx

—(cos udx

\ _ dudx

(sin u)

~(u/v) --

dx

i du

fV— -

\ dx

V2

dv \

u — )

dxl

dx

>_ du _dx

dvdx

d

du

vu'"7x 4

dv(\OQU)Wjx

dx

e«dudx

^(log u)

_L du

u dx

Table 2: A

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Listing 5: The function definition of INFIX, the output parser. INFIX converts its inputfrom Cambridge prefix notation to mathematical infix notation. INFIX also performsalgebraic simplification.

(DEF INFIX(E)(COND((ATOM E)E)(T(PROG(FIRST SECOND)

(SETQ FIRST(INFIX(CAR(CDR E))))(COND((CDR(CDR E))

(SETQ SECOND(INFIX(CAR(CDR(CDR E)))))))(RETURN(COND((EQ(CAR EXQUOTE ADD))(COND((EQ FIRST 0)SECOND)C(EQ SECOND 0)FIRST)((TWONUMXEVAL E NIL))((EQUAL FIRST SECOND)(LIST 2(QUOTE *)FIRST))((MATCH(LIST(QUOTE ?)(QUOTE *)FIRST)SECOND)(INFIX(LIST(QUOTE TIMES)

(LIST(QUOTE ADD)(CAR SECOND)1)FIRST)))((MATCH(LIST(QUOTE ?)(QUOTE *)SECOND)FIRST)(INFIX(LIST(QUOTE TIMES)

(LIST(QUOTE ADD)(CAR FIRST)1)SECOND)))(T(LIST FIRST(QUOTE " + ")SECOND))))((EQ(CAR EXQUOTE TIMES))(COND((EQ FIRST l)SECOND)((EQ SECOND DFIRST)((EQ FIRST 0)0)((EQ SECOND 0)0)((EQUAL FIRST SECOND)(LIST FIRST(QUOTE t)2))((TWONUMXEVAL E NIL))

((MATCH(LIST FIRST(QUOTE IXQUOTE ?))SECOND)(INFIX(LIST(QUOTE EXPT)FIRST

(LIST(QUOTE ADD)(CAR(CDR(CDR SECOND)))1))))((MATCH(LIST SECOND(QUOTE IXQUOTE ?))FIRST)(INFIX(LIST(QUOTE EXPT)SECOND

(LIST(QUOTE ADD)(CAR(CDR(CDR FIRST)))1))))((MATCH(LIST(QUOTE ?)(QUOTE *)FIRST)SECOND)(INFIX(LIST(QUOTE TIMES)(CAR SECOND)(LIST(QUOTE EXPT)FIRST2))))((MATCH(LIST(QUOTE ?)(QUOTE *)SECOND)FIRST)(INFIX(LIST(QUOTE TIMES)(CAR FIRST)(LIST(QUOTE EXPT)SECOND2))))

Listing 5 continued on page 228

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Listing 5 continued:(T(LIST FIRST(QUOTE *)SECOND))))«EQ(CAR EXQUOTE DIV))(COND((EQ SECOND DFIRST)

((EQUAL FIRST SECOND)l)((EQ FIRST 0)0)((TWONUMXEVAL E NIL))

((MATCH(LIST(QUOTE ?)(QUOTE *)SECOND)FIRST)(INFIX(LIST(QUOTE TIMES)(LIST(QUOTE SUB)(CAR FIRST)1)SECOND)))((MATCH(LIST(QUOTE ?)(QUOTE *)FIRST)SECOND)(INFIX(LIST(QUOTE DIV)1

(LIST(QUOTE TIMES)(LIST(QUOTE SUB)(CAR SECOND)1)FIRST))))((MATCH(LIST SECOND(QUOTE t)(QUOTE ?))FIRST)(INFIX(LIST(QUOTE EXPT)SECOND

(LIST(QUOTE SUB)(CAR(CDR(CDR FIRST)))1))))((MATCH(LIST FIRST(QUOTE t)(QUOTE ?))SECOND)(INFIX(LIST(QUOTE DIV)1

(LIST(QUOTE EXPT)FIRST(LIST(QUOTE SUB)

(CAR(CDR(CDR SECOND)))1)))))(T(LIST FIRST(QUOTE /)SECOND))))((EQ(CAR E)(QUOTE EXPT))(COND((EQ SECOND DFIRST)((EQ SECOND 0)1)((TWONUM)(EVAL E NIL))(T(LIST FIRST(QUOTE t)SECOND))))((EQ(CAR E)(QUOTE SUB))(COND((EQ SECOND 0)FIRST)

((EQ FIRST 0)(LIST(QUOTE "-")

SECOND))((TWONUM)(EVAL E NIL))((EQUAL FIRST SECOND)0)(T(LIST FIRST(QUOTE"-")SECOND))))«EQ(CAR E)(QUOTE LOG))(COND((EQ FIRST 1)0)

(T(LIST(QUOTE LOG)FIRST))))((EQ(CAR E)(QUOTE SIN))(LIST(QUOTE SIN)FIRST))((EQ(CAR EXQUOTE COS))(LIST(QUOTE COS)FIRST))((EQ(CAR E)(QUOTE EXP))(COND((EQ FIRST 0)1)(T(LIST(QUOTE EXP)

FIRST))))

Listing 5 continued on page 230

228 September 1981 © BYTE Publications Inc

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11 TAXDEP Cash flow vs. depreciation tables

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13 CHECKBK1 Checkbook maintenance program

14 MORTGAGE/A Mortgage amortization table

1 5 MCILTMON Computes time needed for money to double, triple,

16 SALVAGE Determines salvage value of an investment

17 RRVARIN Rate of return on investment with variable inflows

I 8 RRCONST Rate of return on investment with constant inflows

19 EFFECT Effective interest rate of a loan

20 FVAL Future value of an investment {compound interest)

21 PVAL Present value of a future amount

22 LOANPAY Amount of payment on a loan

23 REGVVTTH Equal withdrawals from investment to leave 0 over

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40 EXPVAL Expected value analysis

41 BAYES Bayesian decisions

42 VALPR1NF Value of perfect information

43 VALADINF Value of additional information

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46 TRAMS Transportation method for linear programming

47 EOQ Economic order quantity inventory model

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49 CVP Cost-volume-profrt analysis

50 CONDPROF Conditional profit tables

51 OPTLOSS Opportunity loss tables

52 FGKJOQ Fixed quantity economic order quantity model

NAME DESCRIPTION

53 FQEOWSH As above but with shortages permitted

54 FQEOQPB As above but with quantity price breaks

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56 NCFANAL Met cash-flow analysis for simple investment

57 PROF1ND Profitability index of a project

58 CAP1 Cap. Asset Pr. Model analysis of project

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59 WACC Weighted average cost of capital

60 COMPBAL True rate on loan with compensating bal. required

61 DISCBAL True rate on discounted loan

62 MERGAMAL Merger analysis computations

63 FINRAT Financial ratios for a firm

64 MPV Met present value of project

65 PRIMDLA^S Laspeyres price index

66 PR1NDPA Paasche price index

67 SEAS1MD Constructs seasonal quantity indices for company

68 TIMETR Time series analysis linear trend

69 TIMEMOV Time series analysis moving average trend

70 FUPRINF Future price estimation with inflation

71 MAILPAC Mailing list system

72 LETWRT Letter writing system-links with MAILPAC

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80 INVENT2 In memory inventory control system

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85 TERMSPAY Compares 3 methods of repayment of loans

86 PAYNET Computes gross pay required for given net

87 SELLPR Computes selling price for given after tax amount

88 ARBCOMP Arbitrage computations

89 DEPRSF Sinking fund depreciation

90 (JPSZONE Finds (JPS zones from zip code

91 ENVELOPE Types envelope including return address

92 AUTOEXP Automobile expense analysis

93 INSF1LE Insurance policy file

94 PAYROLL2 In memory payroll system

95 D1LAMAL Dilution analysis

96 LOANAFFD Loan amount a borrower can afford

97 RENTPRCH Purchase price for rental property

98 SALELEAS Sale-leaseback analysis

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Listing 5 continued-

((EQ(CAR EXQUOTE FAQ)(COND((EQ FIRST 1)1)((EQ FIRST 0)1)(T(LIST FIRST(QUOTE !)))))(T E)))))))

Listing 7: TWONUM simply checks to see if the variables FIRST and SECOND arenumbers. If so, it returns T (for true); otherwise, it returns NIL.

Listing 6: MATCH, an elementary pat-tern matcher, used by INFIX to simplifyalgebraic expressions by recognizing suchthings as the multiplicative and additiveidentities.

(DEF MATCH(X Y)

(COND((EQ X(QUOTE ?))T)

((AND(ATOM X)(EQ X Y))T)((OR(ATOM X)(ATOM Y))NIL)(T(AND(MATCH(CAR X)(CAR Y))(MATCH(CDR X)(CDR Y))))))

(DEF TWONUM( )

(COND((NUMBER FIRST)(NUMBER SECOND))))

Listing 8: In listing 8a DERIV provides the thread which ties PREF, INFIX, and DIFFtogether. The CHR function is analogous to the CHR$ function in BASIC. The sequence(CHR 28)(CHR 31) clears the screen. Listing 8b shows a sample run of the functionDERIV. User input is preceded by the prompt, > .

(8a)

(DEF DERIV( )(PROG( )

(CHR 28)

(CHR 31)

(PRINT(QUOTE(DERIV

(TERPRI)

(TERPRI)LOOP(PRINl(QUOTE >))

(PRINT(INFIX(DIFF(PREF(READ)XPREF(READ)))))

(GO LOOP)))

A SYMBOLIC DIFFERENTIATOR)))

Text continued from page 222:

necessary to translate the output fromLISP notation to infix notation. Thisprocess is performed by the outputparser, INFIX, shown in listing 5.This function generously uses anotherfunction, MATCH, shown in listing6, which was described lucidly byWilliam A Kornfeld in the BYTE LISPtheme issue (see reference 3).MATCH receives two arguments anddetermines whether or not theyfollow the same pattern. If a questionmark, ?, is encountered in the firstargument, any atom of the secondargument will match it. A fewexamples of this "wild-card" usageare in order:

(8b)

> (DERIV)

(DERIV—A SYMBOLIC DIFFERENTIATOR)

>(A/B)B

((- A)/(B12»

> (X * X * X)X(3*(XI2))

> (SIN 2 * X)X((COS(2 * X))* 2)>(LOG X)X(1/X)

>(X t 4)X

(4 *(X t 3))

>(XtN)X

(N *(XI(N - 1)))

Input

(DIFF(QUOTE(ADD A A))(QUOTE A))

(DIFF(QUOTE(TIMES X X))(QUOTE X))

(DIFF(QUOTE(LOG X))(QUOTE X))

(DIFF(QUOTE(COS X))(QUOTE X))

(DIFF(QUOTE A)(QUOTE B))

(DIFF(QUOTE B)(QUOTE B))

Output

(ADD 1 1)

(ADD(TIMES X 1XTIMES X 1))

(TIMES(DIV 1 X)1)

(TIMES(SUB 0(SIN X))1)

0

1

Table 3: Exemplary input and output of DIFF, which differentiates its first argumentwith respect to the second.

(MATCH(QUOTE(A B Q)(QUOTE(A B C))) = T

(MATCH(QUOTE(A B D))(QUOTE(A B C))) = NIL

(MATCH(QUOTE(A B ?))(QUOTE(A B C))) = T

Once patterns are recognized byINFIX, the straightforward parsingoperation begins. INFIX is also con-figured to recognize the multiplicativeand additive identities as well asmany algebraic simplifications.

The nerve center of INFIX is aPROG function that calls itself recur-sively on the first and, if necessary,the second argument of the inputexpression. This, in effect, allows IN-FIX to get to the bottom of things.The use of the variables FIRST andSECOND prevents INFIX fromhaving to recompute them at everyencounter. INFIX uses the functionTWONUM (given in listing 7), whichdetermines if both arguments are

230 September 1981 © BYTE Publications Inc

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BYTE September 1981 231

A TAYLOR SERIES GENERATOR)))

Listing 9: In listing 9a, the function definition of TAYLOR illustrates the use of PROGas an iterative programming mechanism. Listing 9b shows a sample run of the functionTAYLOR. The > prompt precedes user input. The output consists of a list of the termsof the generated Taylor series. The resulting series is obtained by summing the terms.User input consists of the function to be expanded, the value about which the expansionis to occur, and the number of terms desired.

(9a)

(DFF TAYLORC )(PROG( )

(CHR 28)

(CHR 31)

(PRINT(QUOTE(TAYLOR '

(TERPRI)

(TERPRI)LOOP(PRINl(QUOTE >))

(TS(PREF(READ))(READ)(READ)(READ))

(GO LOOP)))

(9b)

> (TAYLOR)(TAYLOR—A TAYLOR SERIES GENERATOR)

> (EXP X)X 0 51

X

((Xt2)/(2 !))((Xt3)/(3 !))((XI4)/(4 !))END

>(SINX)X0 60X0

((-1 *(X!3))/(3!))0

«Xt5)/(5 !))END

>(1/X)X 1 31

(-1 *(X - 1))((2 *((X - l)l2))/(2 !))END

Listing 10: The function definition of TS, the workhorse of the Taylor-series routine.The second argument of EVAL in the function definition illustrates how the pro-grammer can specify the environment by building an appropriate A-list.

(DEF TS(E X A I)(PROG(N)(SETQ N 0)LOOP(PRINT(INFIX(LIST(QUOTE DIV)

(LIST(QUOTE TIMES)(EVAL E(LIST(CONS(QUOTE X)A»)(LIST(QUOTE EXPT)(LIST(QUOTE SUB)XA)N»(LIST(QUOTE FAC)N))))(SETQ N(ADD N 1))

(COND((EQ N J)(RETURN(PRINT(QUOTE END)))))(SETQ E(PREF(INFIX(DIFF E X))))(GO LOOP)))

numbers. If so (EVAL E NIL) isexecuted, which allows INFIX toactually evaluate the expression.Note that the specified A-list is NIL,since no variable bindings(assignments) are required by EVAL.

Tying the Knot

Now that the actors of thedifferentiation are cast, it is necessaryto develop a plot by which they canperform. The function DERIV,shown in listing 8a, serves this pur-pose. It requires no arguments andbegins its duty with housekeepingchores such as clearing the screen andprinting a title. It then prints the IN-FIX of the DIFF of the PREF of READ,or, more simply stated, it prints thederivative of an expression input bythe user in infix notation. Upon com-pletion, the process is repeated adinfinitum. A sample run of DERIV isgiven in listing 8b.

Taylor-Series Expansion

Any standard college calculus text-book (such as reference 5) will tell usthat the Taylor series is:

fix)

00

fin)(a)(x - a)nnl

where a is the value about which theexpansion is to be taken (noting thatif a is 0 the Taylor series reduces tothe Maclaurin series), x is the variableof the original function, and n is aninteger such that 0 < n < oo.

It is a relatively simple undertakingto write a Taylor-series programutilizing PREF, DIFF, and INFIX, asindicated by listings 9a and 10. TheTaylor function is entered when youtype (TAYLOR). It then awaits yourinput, which consists of:

1. function to be expanded

2. variable about which to expand

3. value about which expansion is

to occur

4. number of terms desired

An example of a typical Taylor run ispresented in listing 9b.

Final Remarks

The programs in this articledemonstrate the ease with which

232 September 1981 © BYTE Publications Inc

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symbolic mathematics can be ex-pressed in LISP. When viewed withinthe LISP environment, recursive con-cepts become clear and concise. Bysubstituting different functionalmodules for the DIFF function in theaforementioned treatment, you caneasily develop powerful special-purpose systems. For instance, DIFFcould be replaced by a function whichdoes one or more of the following:vector calculus, Laplace transforms,integration, matrix algebra, complexarithmetic, Boolean algebra, ortrigonometric simplification.

There are other areas where LISP isthe language of choice. These areasinclude pattern matching, theoremproving, and intelligent robotic soft-ware. It is my hope that this articlehas shown that LISP is ideally suitedfor symbolic mathematics and thatLISP should be added to the reper-toire of all serious programmers. ■

The LISP interpreter is sold by SupersoftAssociates, POB 1628, Champaign IL 61820.Versions are available for 16 K-byte RadioShack TRS-80 Model I and Model III com-puters (floppy disk, $100; cassette tape, $75). Aversion to run under the CP/M operatingsystem will be released shortly. The symbolic-differentiation program discussed in this articleis distributed with the disk versions of theinterpreter.

References

1. Berkeley, Edmund C and Daniel GBobrow, editors. The ProgrammingLanguage LISP: Its Operation and Applica-tions. Cambridge MA: MIT Press, 1974.

2. Knuth, Donald E. The Art of Computer Pro-gramming, Volume 1, Basic Algorithms.Reading MA: Addison-Wesley, 1973.

3. Kornfeld, William A. "Pattern-Directed In-vocation Languages." BYTE, August1979, page 34. (Also see other articles inthat issue.)

4. McCarthy, J et al. LISP 1.5 Programmer'sManual. Cambridge MA: MIT Press, 1979.

5. Protter, Murray H and Charles B Morrey,Jr. College Calculus with AnalyticGeometry, second edition. Reading MA:Addison-Wesley, 1970.

6. Siklossy, Laurent. Let's Talk LISP.Englewood Cliffs NJ: Prentice-Hall, 1976.

7. Winston, Patrick Henry. ArtificialIntelligence. Reading MA: Addison-Wesley, 1977.

8. Wylie, C R, Jr. Advanced EngineeringMathematics, third edition. New York:McGraw-Hill, 1966.

234 September 1981 © BYTE Publications Inc

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ATARI 800 Atari Optional Accessories

(16IG Personal BlI<?inP«?<! Model # Description Price

^lory rtrouridl DUbineSS 810 Disk Drive System ..$ 475.00

LOmpUter Features: 815 Disk Drive System.. $1199.00

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Assembled & Tested

Catalog Request

Please send me your 1981 ASAP Full Line CatalogName

CompanyAddress .

City

State _

Title.

Zip-

Atari SOftWare (Many more available)

Super Breakout $30.00

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Printers

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Anacom-150 S 995.00

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Description

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ASAP offers a 120-day buyer protection policy: full money-back guarantee if

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Circle 30 on inquiry card.

Knowledge-Based ExpertSystems Come of Age

Question: What do the followingtasks have in common? Diagnosingbacterial infections; choosing a goodspot on a mountain to drill formolybdenum; configuring the manycomponents that make up a DECVAX-11 computer; determining thestructure of a complex molecule frommass spectrogram data.

Answer: They are important anddifficult decision-making jobs thatonly a few experts do well. Thereasoning process in each job includesuse of judgment, rules of thumb, andexperience. Furthermore, these jobscan all be done today by computerprograms known as knowledge-basedexpert systems.

What makes knowledge-based ex-pert systems different from otherlarge computer programs written tosolve special decision-making prob-lems? We will answer that question inthis article and explain how expertsystems work. We will brieflydescribe several existing expertsystems, and show the operation ofone—a mineral-exploration programwe helped develop. As a bonus, wewill provide a micro expert-system in

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BASIC for your personal computer.

Since work on expert systems grewout of research on AI (artificial in-telligence), a few historical observa-tions will provide some perspective.As is clear from this special issue of

IF-THEN rules are used

to capture the kind of

"semllogical" response

to familiar patterns

that characterizes

much of everyday

human thinking.

BYTE, AI is concerned with makingcomputers perceive, reason, andunderstand. Early work in AI lookedfor simple and powerful reasoningtechniques that could be applied tomany different problems. A classicexample is the work of Newell, Shaw,and Simon on a program called GPS(see reference 21). Intended to be ageneral problem solver, GPS couldprove theorems and solve puzzles and

a wide variety of logical problems.Thus, the generality of its particularreasoning technique—called means-ends analysis—was convincinglydemonstrated.

Unfortunately, attempts to applysuch general methods to larger andmessier real-world problems weremostly unsuccessful. The methodswere not wrong, they were just insuf-ficient. They did not address the dif-ficulties of reshaping a problem into aform the programs could work on.Nor could these general methods, bythemselves, cope with the enormoussearch spaces of alternatives.

How do people cope with thesesame problems? One answer is thatpeople know much more than com-puters. People rarely solve problemsby reasoning everything out from thefirst principles. While recreationalpuzzles can often be solved by strictlogical deduction, many real-worldproblems seem to be solved by"semilogical" methods, such asrecognizing one of a thousandfamiliar patterns applying to the cur-rent situation and recalling the ap-propriate thing to do when that pat-

238 September 1981 © BYTE Publications lnc

Pure Computing Power

The MicroFrame® is Pure Power for comput-ing. It is the industry standard for high quality,reliable S-100 mainframes.

TEI manufactures each MicroFrame® withgreat care. They deliver pure regulated powerat the proper level, improving the reliability ofyour computer. Typically, the output voltagesremain virtually constant, even when the pow-er line voltage varies widely. The MicroFrame®will never notice a brown-out.. .and it provides100 db noise rejection, protecting your com-puterfrom power line voltagespikes and noise.Complies with l-EEE S-100.

The combination of the lowest noise bus, aregulated power system and a rugged chassisproduces a MicroFrame® without equal.

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tern occurs. In everyday affairs,logical deduction is an adjunct toother mental processes.

Recognizing that knowledge is asimportant as reasoning, AI research-ers have worked on a variety ofmethods for representing and usingknowledge. They have also grappledwith fuzzier kinds of problems, wherelogic is supplemented by hunchesbased on experience and judgment.One result has been the developmentof several knowledge-based expertsystems—programs that exploitspecial knowledge to solve difficultproblems in specialized areas. Theseprograms include the DENDRAL pro-gram for mass-spectrum analysis (seereference 14), the MYCIN program(reference 27) and several others

(references 18 and 25) for medicaldiagnosis, the PROSPECTOR pro-gram for mineral exploration(reference 11), and the Rl programfor configuring VAX computersystems (reference 20).

Representing Knowledge in Rules

How do you represent theknowledge needed to do these kindsof tasks? That is still a matter ofdebate and active research in AIcircles. One popular approach is touse IF-THEN rules (also calledsituation-action rules or productionrules). These rules say that if a certainkind of situation arises, a certain kindof action can be taken. They aretypically used to capture the kind of"semilogical" response to familiar

1a

The R1 system (configuring VAX systems):

IF: (1) The current context is assigning devices to Unibus modules, and

(2) There is an unassigned dual-port disk drive, and

(3) The type of controller it requires is known, and

(4) There are two such controllers, neither of which has any devicesassigned to it, and

(5) The number of devices that these controllers can support is known

THEN: (1) Assign the disk drive to each of the controllers, and

(2) Note that the two controllers have been associated and that each sup-ports one device.

1b

The MYCIN system (medical diagnosis):

IF: (1) The site of the culture is blood, and

(2) The identity of the organism is not known with certainty, and

(3) The stain of the organism is gramneg, and

(4) The morphology of the organism is rod, and

(5) The patient has been seriously burned

THEN: There is weakly suggestive evidence (0.4) that the identity of theorganism is pseudomonas.

1c

The PROSPECTOR system (mineral exploration):

IF: There is hornblende pervasively altered to biotiteTHEN: There is strong evidence (320, 0.001) for potassic zone alteration.

Table 1: Sample IF-THEN rules from three knowledge-based expert systems. Tablela shows a rule that the Rl system uses to configure DEC's VAX systems. Table lbshows a rule that the MYCIN system uses to perform medical diagnosis. The number0.4 indicates the degree to which the conclusion follows from the evidence on a scaleof 0 to 1. Table lc shows a rule used by PROSPECTOR in mineral exploration. Thenumber 320 indicates how sufficient the evidence is for establishing the hypothesis ifthe evidence is, in fact, present; the number 0.001 indicates the degree to which theabsence of this evidence will rule out the hypothesis. Both these numbers aremultipliers. Values greater than 1 increase the likelihood of the sufficiency or necessi-ty of the evidence for establishing the hypothesis, and values less than 1 decrease thelikelihood.

Engineers and otherAerospace Professionals

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240 September 1981 © BYTE Publications Inc

#

Engineers and other Aerospace Professionals

Your great ideas todaycould become a great advance tomorrow

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When you join Martin Marietta, you'll find theexcellent salary and complete benefits coverageyou'd expect from an industry leader. Learnabout career opportunities in Orlando, or ourother locations by sending your resume or aletter to the facility of your choice.

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patterns that characterizes much ofeveryday human thinking. Table 1lists examples of rules from severalrule-based systems.

In general, rules like these representa "chunk" of knowledge about a par-ticular field. Most existing rule-basedsystems contain hundreds of rules,

SINGLE RULE

usually obtained by interviewing ex-perts for weeks or months. For exam-ple, the MYCIN system containsabout 450 rules; the Rl system hasabout 800, and the PROSPECTORsystem has about 1600. In anysystem, the rules become connectedto each other to form rule networks.

NETWORK OF RULES

HYPOTHESIS

EVIDENCE

HI

/

/

\

El

H2

H3

/

/

\

/

\

x

H4

E2

E3

/

\

S

E4

E5

Figure 1: Combining rules into networks. Expert systems may consist of hundreds of IF-THEN rules combined into networks like these,

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Once assembled, such networks canrepresent a substantial body ofknowledge. Figure 1 illustrates howrules are combined together into net-works.

An expert usually has many judg-mental or empirical rules according towhich the evidence supports a conclu-sion or hypothesis, but with less thanabsolute certainty. In these cases,numerical values are associated witheach rule to indicate the degree towhich the hypothesis or conclusionfollows from the evidence. Table 1shows two examples of such rule-strength values: in the case of MYCIN(table lb), the value 0.4 (on a 0 to 1scale) means that the conclusion isweakly suggested from the evidence.In the case of PROSPECTOR (seetable lc), two numbers aregiven—one indicates how sufficientthe evidence is for establishing thehypothesis if the evidence is present,the other indicates the necessity of theevidence for the hypothesis, ie: thedegree to which the absence of thatevidence will rule out or "kill" thehypothesis. (There is more about themeaning of these numbers in the latersection on PROSPECTOR.)

The rules are not implemented assubroutines or in any other part ofthe code of the program. Instead, therules for a particular task are writtenin a specialized language, which isthen input by the program to producean internal representation that makesthe expert system an expert aboutthat task domain. The program itselfis only an interpreter and a general-reasoning mechanism. This illustratesan important distinction betweenrule-based systems and more conven-tional computer programs: there is aclear separation of general knowledgeabout the problem (the rules forminga knowledge base) from informationabout the current problem (the inputdata) and methods for applying thegeneral knowledge to the problem(the rule interpreter). Figure 2 il-lustrates this contrast. (Lines 3880through 4040 of listing 1 give a set ofrules input to that program.)

Putting Knowledge to Work

After the knowledge has been en-

242 September 1981 © BYTE Publications Inc

Circle 150 on inquiry card.

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Circle 151 on inquiry card. BYTE September 1981 243

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BYTE September 1981

245

coded as rules, how can it be put touse? This question has more than oneanswer. One general approach is theuse of a production system (seereference 10). A production systemcontains three major components—aset of rules, a global data base, and arule interpreter. Some people call theset of rules the knowledge base andthe rule interpreter the inferencesystem. McDermott calls the globaldata base the working memory, usingthe term "data base" for a file of need-ed facts (see reference 20). Despitethis variety of terminology, the basicideas are the same. The rules have thefollowing general form:

IF: < antecedents

<antecedentm>THEN: <consequentswith certainty Ci

< consequent, >with certainty C„

The antecedents can be thought ofas patterns that can be matchedagainst entries in the data base, andthe consequents as actions that can beperformed (or conclusions that can bededuced) if all the antecedents match.In the case of the Rl example (seetable la), the data base would containassertions about such things as what

MOST

TRADITIONAL

PROGRAMS

the current context is, and whether ornot there is an unassigned dual-portdisk drive. The consequent actionscan cause changes to the contents ofthe global data base, by changing anassertion about the status of theassignment of devices to a controller,or by asking the user a question andadding the answer given to the database. Thus, the application of a rulecan change the state of the data base,enabling some rules and disablingothers.

Control Strategies

How are the enabled rules found,and what decides which rules to ap-ply? This is the job of the rule inter-preter, and the strategy it follows iscalled the control strategy.

One of the simplest strategies is toscan through the rules until one isfound whose antecedents matchassertions in the data base. The rule isapplied, updating the data base, andthe scanning resumes. This processcontinues until either a goal state isreached or no applicable rules arefound. Rl uses a variant of this basicprocedure. Since the behavior of thesystem is directly responsive to thefacts about the problem entered in theglobal base, this is known as a data-driven control strategy. This strategyis also known as forward-chaining orantecedent reasoning.

We think of each rule as asubroutine. Instead of being called byname, a production-system sub-routine is triggered by the appearance

RULE-BASEDPROGRAMS

Figure 2: Contrast between traditional programs and rule-based programs. A rule-based program is divided into a general-reasoning program, called the rule interpreter,and a file of judgmental rules obtained from an expert, called the rule base or knowledgebase. The rule interpreter loads the rule base into an internal representation and uses therule base to guide an interactive consultation with the user.

of certain patterns in the data base.Anathema to lovers of structuredprogramming, such pattern-directedsystems have long fascinated AIresearchers (see reference 32). In par-ticular, the use of such systems aspsychological models was pioneeredby Newell and Simon (reference 22)in the development of GPS.

A different strategy is to select agoal to be achieved and scan the rulesto find those whose consequent ac-tions can achieve the goal. Each suchrule is tried in turn. If the antecedentsfor a rule match existing facts in thedata base, the rule is applied and theproblem solved. If an unmatchedantecedent is encountered, arrangingconditions to match that antecedentbecomes a new subgoal, and the sameprocedure is applied recursively. Ifthere are no rules to establish the newsubgoal, the program asks the userfor the necessary facts and entersthem in the data base. Since thebehavior of the system is directlyresponsive to the goals the system istrying to achieve, this is known as agoal-driven control strategy. (Thisstrategy is also known as backward-chaining or consequent reasoning,and is closely related to means-endanalysis.) A variant of a goal-drivencontrol strategy is used successfullyby MYCIN and is the method used inthe micro expert-system described inthe last section of this article. (It ispossible to use other controlstrategies that combine elements ofdata-driven and goal-driven policies,as we did in our work on PROSPEC-TOR. See reference 11.)

System Characteristics

We can now see more clearly howrule-based expert systems differ frommore conventional computer pro-grams. As mentioned earlier, one ma-jor difference is the separation of theexpert knowledge (the rules forming aknowledge base) from the general-reasoning mechanism (the rule inter-preter). This partitioning, togetherwith the further division of generalknowledge into many separate rules,offers several important advantages:

• incremental development of the

246 September 1981 © BYTE Publications Inc

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BYTE September 1981 247

knowledge base over an extendedtime by letting the developers refineold rules and add new ones

• the same general system can be usedfor a variety of applications, essen-tially by "unplugging" one set of rulesand "plugging" in another

• the same knowledge can be put touse in different ways (includingteaching) by changing the rule inter-preter

• the program can give simple and il-luminating explanations of itsbehavior merely by describing therules it is applying (this also turns outto be a powerful way to debug faultyrules)

• the possibility of developingsystems that are introspective (eg: cancheck the consistency of their ownrules) and evolutionary (eg: canmodify their own rules and learn newones)

All these advantages are present in arudimentary but interesting way inthe micro expert-system described atthe end of this article.

Another characteristic of most ex-pert systems is that they try to mimic,at least to some extent, the way

human experts make decisions. The"spot-a-pat tern/draw-a-conclusion"style of reasoning is used as much byexperts on special problems as it is byall of us on day-to-day problems;what distinguishes the expert fromthe rest of us is the expert's unusualand valuable set of rules. Such rulesare often not conclusive, but onlysuggestive of the conclusion. For ex-ample, if a car won't start and theheadlights are dim, the battery isprobably bad, but there are otherpossibilities. To mimic experts, then,a rule-based system should let the ex-pert state the degree of significance orcertainty that should be attached tothe conclusion of a rule.

A Sampling of Expert Systems

To understand both the capabilitiesand limitations of knowledge-basedsystems, it is helpful to examinespecific systems created to solve par-ticular problems. At first glance, theironly common characteristic seems tobe their reliance on explicitly encodedknowledge. Groupings based on themethod of knowledge representation(eg: production rules) or on the do-main of application (eg: medicine)

Function

Domain

System

Reference

Diagnosis

Medicine

PIP

24

Medicine

CASNET

34

Medicine

INTERNIST

25

Medicine

MYCIN

27

Medicine

PUFF

13

Engineering

SACON

3

Geology

PROSPECTOR

11

Search

Chemistry

DENDRAL

14

Chemistry

SECHS

36

Chemistry

SYNCHEM

16

Problem

Circuit analysis

EL

28

Solving and

Genetics

MOLGEN

29

Planning

Mechanics

MECHO

6

Programming

PECOS

2

Configuring con-

puters

R1

20

Machine Acoustics

HASP (SU/X)

23

Measurement

Medicine

VM

12

Interpretation

Computer-aided

Electronics

SOPHIE

4

Instruction

Medicine

GUIDON

8

Knowledge

Diagnosis

TEIRESIAS

9

Acquisition

Diagnosis

EMYCIN

30

Diagnosis

EXPERT

33

Diagnosis

KAS

26

System

—

ROSIE

31

Building

—

AGE

23

—

HEARSAY III

1

Table 2: A classification

of existing knowledge-based systems by function. Numbers

at the right indicate references about each

system

(given at the end

of the article).

reveal little additional commonality.However, we can gain some insightby grouping the systems according totheir general function. Table 2 showsa classification of well-knownknowledge-based systems into eightgeneral categories. We will nowdefine most of these categories anddescribe some representative pro-grams.

Diagnosis Problems

The general diagnosis problem isone of classifying an object, event, orsituation on the basis of perhapsuncertain information about itscharacteristics. The categories may ormay not be mutually exclusive, andthe data can be acquired sequentiallyor in parallel. In a formal sense,diagnosis problems can always beposed as problems in statistical-decision theory, whose solutionusually requires the estimation of amultivariate probability functionfrom vast amounts of data. Theknowledge-based-systems approachto such problems effectivelysubstitutes the knowledge and judg-ment of expert humans for thisunknown function.

Several impressive knowledge-based systems have been developedfor medical-diagnosis problems. TheINTERNIST program developed byPople and Myers at the University ofPittsburgh uses information from4000 possible manifestations todiagnose problems of internalmedicine that can involve multiple in-stances of 500 different disease types(see reference 25). The program con-tains a large taxonomy of diseasetypes, together with rules that linkmanifestations to these types, as wellas an ingenious control procedure fornarrowing down the disease classesthat explain the manifestations. Inmany tests, INTERNIST has demon-strated the capability of correctlydiagnosing multiple-disease casesdescribed in medical journals as beingparticularly difficult.

Another well-known medical-diagnosis program is the MYCINsystem developed by Shortliffe andhis colleagues at Stanford (seereference 27). MYCIN is a consulta-

Text continued on page 254

248 September 1981 © BYTE Publications Inc

"Humans are no longer limited to philosophic in-trospection in their strivings for self-knowledge.They can now attempt to analyze and under-stand the workings of the human mechanism."

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PASCAL

SYSTEM

by Kenneth L. Bowles

The most popular Pascalversion explained by its creator

Written by the originator of UCSD PascalSystem, this informative book is an orienta-tion guide to the UCSD Pascal System. Forthe novice, this book steps through the'System, bringing the user to a sophisticatedlevel of expertise. Once familiar with theSystem, the reader will find the guide aninvaluable reference tool for creatingadvanced applications. The package offersprograms which may be run withoutalteration on:

• DEC PDP-11 or General Automationminicomputers

• Western Digital Microengines

• 8080, 8085, Z80, 6502, 6800, 9900 orAM-lOO based microcomputers (includ-ing the popular Apple II and Radio ShackTRS-80 microcomputers)

Dr. Kenneth L. Bowles is Director of theInstitute for Information Systems, Universityof California, San Diego.

ISBN 0-07-006745-7204 pagessoftcover

$11.95

- .j- - s

YOU JUSTBOUGHTA PERSONALWHAT?

by Thomas Dwyer and Margot Critchfield

A Structured Approach toCreative Programming

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Dr. Thomas Dwyer is a Professor ofComputer Science at the University ofPittsburgh

Margot Critchfield is a doctoral studentin Foundations in Education at the Univer-sity of Pittsburgh.

ISBN 0-07-018492-5

343 pages

softcover

78 illustrations

$11.95

BEYOND GAMES:

SYSTEM

SOFTWARE

FOR YOUR

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PERSONAL

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by Kenneth Skier

Creating programs for the Apple,Atari, Challenger andPET computers

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Kenneth Skier is a Systems Programmerfor Wang Laboratories, Inc., and a Lecturerat MIT.

ISBN 0-07-057860-5440 pagessoftcoverillustrated

$14.95

stimulating, provocative, problem-solving

Circle 47 on inquiry card.

BYTE September 1981 251

CIARCIA'S

CIRCUIT

CELLAR

by Steve Ciarcia

Practical uses for home computers

Imaginative and practical, Ciarcia's CircuitCellar details a variety of microcomputerprojects. A collection of the best articlesfrom the popular series in BYTE magazine,this volume includes

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Complete instructions are given on how toconstruct each project. With amusinganecdotes and an easy-going style,Ciarcia presents his material in such amanner that even a neophyte need not beafraid of it.

ISBN 0-07-010960-5

125 pages

softcover

color photographs and diagrams

$8.00

CIARCIA'SCIRCUITCELLAR,VOLUME II

by Steve Ciarcia

More practical uses forhome computers

Composed of popular articles from BYTEmagazine, this volume tells how micro-computers can be uniquely interfaced toour environment. Projects include

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ISBN 0-07-010963-X

224 pages

softcover

photographs and diagrams

$12.95

MICRO-COMPUTERSTRUCTURES

by Henry D'Angelo p

Digital Electronics,Logic Design, andComputer Architecture

Today, there is an increasing demand forcomputer users who are not only well-versedin software, but who can also maintain,modify, and design their own hardwaresystems.

This text introduces computer users withlittle or no background in digital hardwareto the basic computer structures used inmicrocomputer design and microcomputerinterfacing. Helpful examples and end-of-chapter exercises further illustrate thevarious concepts presented, and a detailedbibliography provides additional readingopportunities. As a resource and textbook,it will assist

• programmers and systems analysts

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Detailed Instructor's Manual also available.

Dr. Henry D'Angelo is the Associate Deanof the College of Engineering and Professorof Manufacturing Engineering at BostonUniversity

ISBN 0-07-015294-2288 pageshardcover314 illustrationsavailable spring 1981

$18.95

Instructor's ManualISBN 0-07-015298-5softcover

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Readers can modify the system to meetpersonal needs.

Steve Ciarcia is a Computer Consultant,Electrical Engineer, and author of "AskByte" and "Ciarcia's Circuit Cellar" columrin BYTE magazine.

ISBN 0-07-010962-1330 pagessoftcoveravailable summer 1981

$15.95

BYTE Books' reputation is basedon providing technicallyaccurate, useful, and timelyinformation. Established on thesame principle as BYTEmagazine, BYTE Book's evolvedin response to the rapidly ex-panding audience of homeand business computer users.Computer professionals andenthusiastic newcomers needto keep pace with thisunabated growth. This selec-tion of BYTE books canexpand your library of knowl-edge and expertise.

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252 BYTE September 1981

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Text continued from page 248:

tion designed to diagnose bacterial in-fections and recommend antibiotictherapy. MYCIN is organized aroundthe systematic use of a large collec-tion of rules that link patient data toinfection hypotheses. Formulas basedon a probability-like theory of cer-tainty are used to accommodate theinexact nature of the relevant medicalknowledge. In several ways, the pro-gram exploits the modularity provid-ed by the use of rules to express thismedical knowledge. From a system-development standpoint, modularityallows long-term incremental

development of the system by con-tinual expansion and refinement ofthe rule base. The program obtainsinformation from a user by simplychaining backward through the rules.This lets the program furnish simplebut useful explanations of its reason-ing by stating the rules it is using.

Search

Many problems in graph theory,game theory, and other areas ofdiscrete mathematics can be posed assearch problems. These problems arecharacterized by the existence (at

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least in principle) of a systematicmethod for generating candidatesolutions, as well as a systematicmethod for testing acceptability. Asregards genuinely interesting prob-lems, the number of candidate solu-tions is usually so great that an ex-haustive search is infeasible. Anydevice that significantly reduces theamount of search required (prefera-bly without compromising the quali-ty of the solution) is called a heuristic,and a search strategy guided byheuristics is called heuristic search.

Since the study of heuristic searchwas one of the earliest activities in AI,it is natural that DENDRAL—one ofthe first knowledge-based sys-tems—was concerned with usingknowledge to limit search (seereference 14). Begun in 1965 byFeigenbaum, Lederberg, and theircolleagues at Stanford University,DENDRAL generates plausible struc-tural representations of organicmolecules from mass-spectrogramdata, nuclear-magnetic-resonancedata, and additional constraints pro-vided by the user. The program runsin a plan-generate-test sequence: (1)deriving necessary constraints on themolecular structure, (2) systematical-ly generating structures that satisfythose constraints, and (3) testing theproposed structures by predicting themass spectrogram and rejecting thosethat disagree with the experimentalresults. The knowledge needed forstep 2 is encoded as an ingeniousspecial procedure. The knowledgeneeded for steps 1 and 3 is encoded astables of production rules, a methodcompatible with the way chemiststhink about the rules of mass spec-trometry (see reference 5).

For the molecular families coveredby these empirical rules, the programis said to surpass even expert chemistsin speed and accuracy. The resultsobtained with it have been publishedin many papers in chemistry journals(see reference 13).

Problem Solving and Planning

An important class of logical prob-lems concerns dividing a problem in-to a set of simpler subproblems. Tobe useful, a solution must be con-

254 September 1981 © BYTE Publications Inc

structive; it usually consists of a se-quence of actions that will achievesome goal. Examples of such prob-lems are theorem proving, programsynthesis, and robot planning.

EL is a knowledge-based system forthe steady-state analysis of resistor-diode-transistor circuits (see reference28). It uses production rules to repre-sent general principles, such as Kirch-hoff's laws and Ohm's law, as well asthe characteristics of types of devices.Facts about the circuit being analyzedare represented as assertions in anassociative data base. The rule inter-preter is written in a special languagecalled ARS (antecedent-reasoningsystem). As its name implies, ARSsupports the use of rules in the ante-cedent mode, in which the factualassertions trigger the rules. The ac-tions of the rules create new asser-tions, which in turn trigger additionalrules.

An important property of ARS isthe ability to make conjectures whenno additional direct deductions arepossible, and to keep track of thoseconjectures and any conclusionsdependent upon them should subse-quently detected contradictions re-quire their revision. This abilityallows the analysis of a circuit to pro-ceed when the conducting or noncon-ducting states of its nonlinear devicesare unclear. It also permits the user tomodify the circuit and see the effectsof changes without having to re-analyze the entire circuit. ARS canemploy the same facilities to provideexplanations of its reasoning.

Computer-Aided Instruction

Three types of traditional CAI(computer-aided instruction) areoften distinguished: frame-orienteddrill-and-practice programs (whichare unrelated to what AI people callframe-based representations); gamesand simulations (usually used toteach diagnosis), and exploratorysystems that allow the student to ex-periment freely and learn by doing.Among the limitations of these pro-grams are their inability to conductdialogues with the student in naturallanguage, to respond to unanticipatedresponses, to diagnose the student's

errors, or to improve with ex-perience. The potential applicabilityof artificial-intelligence techniques tosolving these problems was outlinedby Carbonell ten years ago (seereference 7), and a variety of ap-proaches have subsequently been ex-plored. To the extent that knowledgeof the subject matter is required for asolution, knowledge-based systemshave an obvious contribution tomake to CAI.

The GUIDON system developedby Clancey at Stanford exploits theMYCIN knowledge base about men-ingitis and bacteremia to teach both

facts and problem-solving strategies(see reference 8). MYCIN'S 450diagnostic rules were not modified,but were augmented by an additional200 rules that included methods forguiding the dialogue with the student,presenting diagnostic strategies, con-structing a student model, andresponding to the student's initiative.By replacing MYCIN'S rules by aseparate set of MYCIN-style rulesused in the PUFF program fordiagnosing pulmonary disease,Clancey was able to use GUIDON totutor students about pulmonary-function analysis. Thus, GUIDON

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September 1981 © BYTE Publications Inc 255

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MICROPROCESSOR APPLICATIONSMANUAL. By Motorola Semicon-ductor Products, Inc. 720 pp., il-lus., 8V2 x 11 format. With nuts-and-bolts practicality, this manualby the Motorola people (who shouldknow) gives you detailed applica-tions information on micro-processors. Assumes no priorknowledge on your part aboutMPUs.

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ENCYCLOPEDIA OF COMPUTER SCIENCE. Editedby Anthony Ralston and C. L. Meek. 2,500 pp., 60illus., 100 charts, 7 x 10 format. This first and onlyin-depth coverage of the entire field of computerscience in a single volume is comprehensive andcompletely up to date.

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DATA STRUCTURES USING PAS-CAL. By Aaron M. Tenenbaum andMoshe J. Augenstein. 544 pp., il-lus. With its emphasis on struc-tured design and programmingtechniques, this definitive worktakes you on a trailblazing journeythrough Pascal. Separate chaptersare devoted to the stack, recursion,queues and lists, Pascal list pro-cessing, trees, graphs and theirapplications.582230-X $23.95

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BYTE September 1981 257

has shown that a knowledge-basedsystem can be exploited for teachingabout its knowledge base.

Knowledge Acquisition

As an alternative between the ex-tremes of complete handcrafting ofthe knowledge base and completelyautomated learning, researchers haveinvestigated the development ofvarious tools that can facilitate theprocess of acquiring knowledge. Themost ambitious of these is Davis'TEIRESIAS system that employsknowledge about the MYCIN systemto supervise interaction with an ex-pert in building or augmenting aMYCIN rule set (see reference 9).

Giving the expert direct access tothe program is an appropriateultimate goal. But the expert usuallylacks sufficient understanding of theprogram's representational mecha-nisms to appreciate the consequencesof the many choices the program of-fers. An alternative to direct access isto use a computer scientist whounderstands the program's mecha-

nisms and provide specific toolsmatched to the knowledge-acquisition process.

KAS, the knowledge-acquisitionsystem developed by Reboh forPROSPECTOR, is an example ofsuch a system (see reference 26).PROSPECTOR employs variouskinds of networks to representknowledge—rule networks for ex-pressing judgmental knowledge,semantic networks for expressing themeaning of the propositionsemployed in the rules, and taxonomicnetworks for representing staticknowledge about the relations amongterms in the domain. The core of KASis a network editor. The editor's basicoperations allow it to create, modify,or delete various kinds of nodes andarcs. The network editor knowsabout the various mechanismsemployed by PROSPECTOR, pro-tects the user against certain kinds ofsyntactic errors, and includes asystem that keeps track of partialconstructs that remain to be com-pleted. At any time, the user can turn

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control over to KAS, and KAS willsystematically question the user to fillin the missing parts of the structures.A semantic network matcher givesthe user a limited ability to edit bycontent rather than by form. SinceKAS is embedded in PROSPECTOR,it lets the user determine the effects ofchanges by permitting controlled ex-ecution of the program. Althoughspecialized to PROSPECTOR, KASgives powerful assistance in the time-consuming task of developing theknowledge base.

System Building

Many knowledge-based systemsthat have been built—especially inthe area of diagnosis—have generallysimilar structures. In particular, allrule-based systems have a rule inter-preter, a collection of rules making upthe knowledge base, and a globaldata base of assertions about the par-ticular case being diagnosed. Severalresearchers have illustrated thegenerality of their systems by show-ing that they can be applied toanother domain merely by removingthe rules for a given domain andsubstituting rules for the new one (seereferences 17 and 30).

Every domain, however, has itsown peculiarities. Despite the goodintentions of system builders, thesepeculiarities inevitably influence thedesign of a system. As a result, aserious attempt to build a newknowledge-based system almostalways requires changes in all parts ofthe system. Recognizing these facts,researchers have recently begundeveloping what amount to program-ming languages for building expertsystems. While these languages arejust coming into use and are certain toundergo further development, theypromise to reduce significantly theprogramming effort needed todevelop a new system.

AGE is a good example of the mostrecent efforts in this direction (seereference 23). Specifically designed toallow the implementation of a broadspectrum of knowledge-basedsystems, AGE gives the designer a setof separate, interconnectable,preprogrammed modules for im-

258 September 1981 © BYTE Publications Inc

(3a)

SYMBOLIC NAME

TOP

0.5-

TEXT DESCRIBING ASSERTION

PRIOR PROBABILITYASSERTION

LIKELIHOODRATIOS

♦VARIABLE LIKELIHOODRATIO (DEFINED INFIGURE 3b)

CONTEXTIN

ALTERNATIVEHYPOTHESIS

TERVAL—' I il

2,0.01 J *Hx)

CNTX

NEEDEDCONTEXT

1

Lin)

10

5

i

(3b)

1

/I

y i

s i

l\

1 \

1

10

20

30

X

BAD NEWS( MOST

UNFORTUNATEEVIDENCE)

Figure 3: Diagram showing some of the constructs used in the PROSPECTOR inference networks. In figure 3a, boxes represent asser-tions. Each assertion's symbolic name is at the upper-left corner of the box and text describing the assertion is inside the box. Mostassertions have prior probability values shown at the upper-right corner of the box. Evidence can be combined by logical connectivessuch as AND, OR, and NOT, represented by circles inside boxes; by plausible inference rules, indicated by two rule-strength values,LS and LN (LS indicates how sufficient the evidence is for establishing the hypothesis, if the evidence is present; LN indicates hownecessary the evidence is for the hypothesis), and by variable likelihood ratios [L(x)], defined in figure 3b. Dashed arrows indicatecontextual constraints, which can "turn on or off" one question or a whole section of the network (at the tail of the arrow), dependingon the answer to another question (at the head of the arrow). Figure 3b shows a plot defining a likelihood ratio L(x) for a numericalanswer x to a question from PROSPECTOR. The likelihood ratio depends on the numerical value provided by the user.

plementing the knowledge base, theinterpreter, and the data base. It alsoprovides ways to escape to the hostprogramming language to implementarbitrary procedures. The knowledgebase can be represented either as setsof production rules or as framesystems (called units), or the tworepresentations can be combined. Forthe interpreter, AGE supplies stan-dard procedures for forward-chainingand backward-chaining, plus conve-nient ways to implement otherstrategies. The standard global database is a so-called blackboard system(see reference 19). AGE also containsknowledge about its own facilitiesand procedures, and a tutor sub-system that lets the user browse inthis on-line manual. A design sub-system provides on-line advice on theuse of AGE itself.

The design of any programminglanguage always involves a com-promise among convenience,generality, and efficiency (in time orspace). Clearly, systems like AGE,ROSIE, HEARSAY III, and RLL, areattempts to gain convenience,generality, and design-time efficiencyfor relatively modest additional costin space and run-time efficiency.While there is not yet enough ex-perience with such systems to assesstheir value, we expect them to play asignificant role in futuredevelopments.

PROSPECTOR: Sample System

Supported by the US GeologicalSurvey and the National ScienceFoundation, we developed the PROS-PECTOR system for mineral explora-

tion (see reference 11). PROSPEC-TOR contains rule-based models ofdifferent kinds of ore deposits. Wedeveloped each model by interview-ing a geologist who is an authority ona particular class of deposits, andthen translating the geologist'sknowledge of the associations be-tween field-observable evidence andrelevant geological hypotheses into astructured collection of rules. PROS-PECTOR models can perform thesetasks: (1) evaluate the favorablenessof a geologic district for a kind of ore,(2) evaluate the favorableness of aparticular exploration site within adistrict, and (3) evaluate thefavorableness of different drillingsites on an exploration site. In addi-tion, PROSPECTOR can suggestwhich data are most valuable for fur-ther exploration, give the rationale

September 1981 © BYTE Publications Inc 259

for conclusions reached, and provideinformal education about each classof deposits.

PROSPECTOR uses a combinationof artificial-intelligence techniques toperform these tasks. MYCIN-likerules link evidence to hypotheses, andoffer the advantages of modularityand explicability. A mixed-initiativecontrol strategy enables the usereither to let the system use abackward-chaining strategy to gatherinformation, or to interrupt the pro-gram to select different goals or tovolunteer relevant information.

PROSPECTOR accommodatesuncertainty in both evidence andrules. When PROSPECTOR asks yes-or-no questions, the user must in-dicate certainty about the answer ona scale from — 5 to +5, where — 5 is acertain no, 0 means don't know, and+ 5 is a certain yes. When PROSPEC-TOR asks for numerical input—forexample, the geological age of arock—PROSPECTOR also asks forthe user's confidence in the answer.

Figure 3a illustrates the basic formof a PROSPECTOR inference net-work. Each box stands for an asser-tion and has a previously assigned

probability value. There are a varietyof ways to combine evidence. Theseinclude logical operators such asAND, OR, and NOT, represented bycircles, and plausible-inference rules,indicated by the likelihood ratios(rule-strength values) LS and LN. LSindicates how sufficient the evidenceis for establishing the hypothesis ifthe evidence is present. LN indicateshow necessary the evidence is for thehypothesis; that is, the degree towhich the absence of this evidencewill rule out the hypothesis. Boththese likelihood ratios are multipliers.Thus, any value less than 1 decreasesthe likelihood of sufficiency ornecessity; any value greater than 1 in-creases the likelihood.

For questions that requestnumerical input rather than yes-or-noanswers, PROSPECTOR uses a plotlike that shown in figure 3b to com-pute a likelihood ratio. The chart in-dicates the significance of ranges inthe answer: x is the requestednumerical quantity and L{x) is thelikelihood ratio.

PROSPECTOR also uses contex-tual constraints, shown in figure 3a asdashed arrows. These work by telling

The following questions are intended to establish the nature of the petrotectonic setting.(These questions will not be pursued unless a positive answer is given to the next question.)

12 — To what degree do you believe that the target area is in a continental-margin mobilebelt? 4

13 — Do you know the age of the continental-margin mobile belt? WHY

The vast majority of porphyry copper deposits are younger than 200 million years. Major agegroups include:

1. An older group of 200 to 150 m.y. (million year) porphyries in British Columbia;

2. An important younger group of 70 to 50 m.y. deposits in the Mideast, British Col-umbia (Skeena Arch), and Arizona-New Mexico-Sonora (Laramide) copper pro-vince;

3. The major belt of 60 to 4 m.y. deposits in the Andes of Argentina, Chile, Peru,Ecuador, and Colombia.

<The explanation continues with additional information>

13 — Do you know the age of the continental-margin mobile belt? YES

14 — What is the age of the continental-margin mobile belt? CRETACEOUS = 65-136MILLION-YEARS

What is your confidence in this estimate? 3

<The consultation continues on with many additional questions. >

Figure 4: An excerpt from a consultation with PROSPECTOR, which has chosen aninitial hypothesis to investigate and is now asking the user for additional relevant infor-mation. The numerical answer to question 12 indicates the user's degree of certaintyabout a fact, using a —5 to +5 scale. If the user types "WHY" instead of answering aquestion, PROSPECTOR explains the question's geological significance.

PROSPECTOR, in effect, "Don'teven consider hypothesis A unless thelikelihood of hypothesis B falls withinsuch and such a range." The range iscalled the context interval. It is de-fined by two numbers on the —5 to+ 5 scale described earlier. The con-text interval (2,5), for example, in-dicates that PROSPECTOR shouldn'tconsider hypothesis A unless con-fidence in the truth of B is somewherebetween lukewarm ( + 2) and ab-solutely certain ( + 5). The defaultcontext interval, in effect when no in-terval is shown, is (0,5).

Figure 4 shows an excerpt from aconsultation with PROSPECTOR.Before the excerpt, the uservolunteered observations about rocksand minerals at the prospective site.PROSPECTOR chose an initialhypothesis for investigation (that acertain type of copper deposit is pres-ent). At the start of the excerpt,PROSPECTOR is asking the user aseries of questions to get additionalinformation. In response to question12, the user types "4" to indicate arelatively strong degree of certaintyabout the answer.

PROSPECTOR can accept a vari-ety of answers to questions. For ex-ample, in answer to question 14, theuser provides the term "cretaceous"to indicate a numerical range ofvalues. When the user types "WHY"instead of answering question 13,PROSPECTOR prints an explanationof the question's geologicalsignificance. By typing "WHY"repeatedly, the user can learn moreabout the expertise captured in themodel. After the explanation, PROS-PECTOR repeats question 13 and theconsultation goes on.

In response to any question, theuser has options to seek clarification,change the course of the questioning,trace the implications of answersgiven, and so on. The consultationcontinues until PROSPECTOR hasconfirmed or rejected the hypothesisunder consideration. PROSPECTORthen explains the basis of its conclu-sions in terms of the rules used.

Tests have shown that evaluationsmade by PROSPECTOR closelymatch those made by the geologists

260 September 1981 © BYTE Publications lnc

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BYTE September 1981 261

who created the models; thenumerical scores typically agree towithin about seven percent on theaverage (see reference 15).

Appropriate Tasks

While the systems we have de-scribed perform a wide variety oftasks, knowledge-based expertsystems are more successful in han-dling some tasks than others. Ingeneral, the following are prerequi-sites for the success of a knowledge-based expert system:

• there must be at least one humanexpert acknowledged to perform thetask well

• the primary source of the expert'sexceptional performance must bespecial knowledge, judgment, and ex-perience

• the expert must be able to explainthe special knowledge and experienceand the methods used to apply themto particular problems

• the task must have a well-boundeddomain of application

Many scientific and technical tasksmeet these conditions, especiallywhere there is a tradition of consulta-tion. Certain kinds of tasks are notgood subjects for knowledge-basedexpert systems. For example,although a mathematician possessesspecialized knowledge, the additionalknowledge needed to function in thatrole is far more extensive than currentknowledge-based expert systems canhandle. On the other hand, wherethere are well-defined mathematicalprocedures for solving a problem,knowledge-based expert systems areunnecessary. For most perceptualproblems, experts are unusual, rele-vant knowledge is extensive but dif-ficult to pinpoint, and generalunderstanding of the perceptual pro-cess is limited. And many tasks arestill waiting for the first expert to ap-pear. An example is earthquakeprediction. There are now no

Photo 1: The area where PROSPECTOR predicts a molybdenum deposit. Given exten-sive data about the surface, PROSPECTOR used its rules to score areas of favorablenessfor molybdenum ore. Ore-grade molybdenum was previously found in the bright areaon the right. PROSPECTOR predicts more ore will be found in the undrilled bright areaon the left. The brighter the area, the higher its rating by PROSPECTOR. The site is inthe Mount Tolman area of the state of Washington.

geologists who can predict earth-quakes accurately. An expert systemfor earthquake prediction should notbe expected to fare any better thanthe human sources of its knowledgebase.

The Future

We are now witnessing the firsttransition of expert programs fromthe comfortable surroundings ofresearch laboratories to the moredemanding world outside. For severalyears, the DENDRAL system has seenregular use by university and in-dustrial chemists throughout thecountry. The Digital Equipment Cor-poration is using one version of Rland is developing versions for otherDEC systems. The PROSPECTORsystem has been applied to severalpractical problems of the USGeological Survey and the USDepartment of Energy. PROSPEC-TOR has also made its first predictionabout the location of a molybdenumdeposit. Drilling is underway to see ifthere is a deposit where PROSPEC-TOR predicted (see photo 1).

Donald Michie and his colleaguesat the University of Edinburgh aredeveloping an expert system similarto PROSPECTOR to diagnoseoperating problems on North Sea oilplatforms. Schlumberger is develop-ing another expert system to interpretthe waveforms obtained when in-struments are dropped down oilwells. Finally, Michie and theMachine Intelligence Corporationhave independently developed thefirst simplified expert systems thatcan be run on an Apple computer.The current generation of expertsystems is being put to practical use,and many more systems will certainlybe built.

Researchers have identified and areattacking several major problems thatlimit progress in knowledge-basedsystems. One of these problems con-cerns software support for research inthis field. As our micro expert-systemillustrates, BASIC is not the rightlanguage for implementing expertsystems. Pascal and even LISP are notcompletely satisfactory either. Newlanguages such as OPS-5, oriented

262 September 1981 © BYTE Publications Inc

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BYTE September 1981 263

Listing I: A rule-based, animal-identification program in BASIC. This is based on theDIAGNOSE program found in chapter 18 of LISP by P H Winston andBKP Horn. Thecore subroutine is VERIFY (lines 1210 through 1830), which is recursive. Since BASICdoes not support recursion, all reentrant subroutines must explicitly save their localvalues on push-down stacks before transferring control.

00010000200003000040000500006000070000800009000100QOU000120001300014000150001600017000180001900020000210002200023000240002500026000270002800029000300003100032000330003400035000360003700038000390004000041000420004300044000450004600047000480004900050000510005200053000540005500056000570005800059000600006100062000630006400065000660006700068000690007000071000720

A RULE-BASED IDENTIFICATION PROGRAM

Based on the DIAGNOSE program in Chapter 18 of the book

"LISP" by P. H. Winston and B. K. P. Horn

A$ = array of asked questions

Al = current number of asked questions

A9 = maximum number of asked questionsF$ = array for facts

Fl = current number of facts

F9 » maximum number of factsH$ = array for top-level hypotheses

HI = current top-level hypothesis

H8 = current number of top-level hypotheses

H9 = maximum number of top-level hypothesesQ « array of rule numbers for deducing a goal hypothesis

(size » R9/5)

Q8 = current number of relevant rules= array for rules

Rl ■ current rule index

R2 = current antecedent

R7 " current number of rules

R8 = current number of bytes used for rules

R9 = maximum number of bytes in R$= array of pointers into R$ (size = R9/5)

Rl = current rule pointer= stack array for strings

51 = stack pointer for S$S9 = size of S$

= stack array for numbers

52 = stack pointer for SS8 = size of S

R$

REM

REMREMREMREMREMREMREMREMREMREMREMREMREMREMREMREMREMREMREMREMREMREMREMREMREMREMREMREMREMREMREM

REM

REM INITIALIZE

DIM A$(100),F$(100),H$(20),Q(50),R$(250),R(50),S$(200),S(200)

A9 = 100

F9 - 100

H9 - 20

R9 = 250

58 = 200

59 = 200

51 = 0

52 = 0

PRINT "Hello."

REM CALL LOADRULES TO INITIALIZE R AND R$; R7 = COUNT OF RULES

GOSUB 3680

> 0 THEN 500

"No rules-"

S$

IF R7PRINTSTOPREM

H8

COUNT OF HYPOTHESES

CALL LOADHYPOTHESES TO INITIALIZE H$,GOSUB 4100IF H8 > 0 THEN 550PRINT "No hypotheses."STOP

PRINT "I will use my ";R7;" rules to try to establish one of the"PRINT "following "H8;" hypotheses:"FOR HI = 1 TO H8PRINT " ";Z$;H$(H1)NEXT HIPRINT

PRINT "Please answer my questions with Y (yes), N (no), or W (why)."PRINTREM

REM THE MAIN LOOP — DIAGNOSEREMAl = 0Fl = 0

FOR HI - 1 TO H8

REM SETUP ARGUMENTS AND GOTO VERIFY TO ESTABLISH THE TRUTH OF Fl$Fl$ = H$(H1)Y = 1GOTO 1200 Listing 1 continued on page 266

toward production development, andnew expert-system-building systemssuch as AGE, HEARSAY III, and RLLare the first of a new generation ofsoftware tools that will simplifysystem development.

On a more fundamental level,something must be done to shortenthe time needed to interview expertsand represent their special knowledgein the form of rules. This is oftencalled the knowledge-acquisitionproblem. Despite several concen-trated efforts, it remains a bottleneck.The development of a model contain-ing a few hundred rules may nowtake several months of the expert'stime and even more of the systembuilder's. Past efforts to speedknowledge acquisition have beenalong three lines: (1) to develop smarteditors that assist in entering andmodifying rules, (2) to develop an in-telligent interface that can interviewthe expert and formulate the rules,and (3) to develop a learning systemthat can induce rules from examples,or by reading textbooks and papers.

Somewhat ironically, to doanything ambitious along these linesseems to require fundamental ad-vances in our understanding of twocore Al topics—the representation ofknowledge and the use of knowledge!The problem is that although in-ference networks of rules do much tocodify the reasoning process that anexpert uses in solving a problem,there's still much that goes on insidean expert's head that doesn't appearin the networks. Basically, aknowledge-based system provides aflexible yet precise language that anexpert can use to describe the chainsof reasoning. We need to developmore expressive languages that allowthe expert to articulate more of thenuances and details of thought pro-cesses. One of the problems is that itis difficult for experts to describe ex-actly how they do what they do,especially with respect to their use ofjudgment, experience, and intuition.We are optimistic that such advanceswill be made, but will resist the temp-tation to make more specific guesses.

The knowledge-acquisition issuetouches on an important side effect of

264 September 1981 © BYTE Publications Inc

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The fact that our patent pendingHOP Digital Data Separator gives ourcontroller packages maintenance-free reliability should convince eventhe dyed-in-the-wool 51/r or 8"floppy disk fanatics.

Si/a" hard disks are the way of thefuture and ACT has an affordable,efficient 51/r hard disk package youcan order off-the-shelf. Just pick upyour phone and call us.

High-performance meets low cost.

In terms of byte-per-dollar cost,51/4" Winchester types are up to fivetimes more affordable than 5V4"floppies, in terms of reliability,efficiency and sheer speed, the 5Whard disks blow everything else rightout of the water.

So if you're looking for the wayto affordably upgrade your ownmicrocomputer system, or yourwhole company's microcomputersystem, call the company thatintroduced high-performance to low-cost. .

Plug-it-in; turn-it-on.

You can order our products inany configuration you desire. Orderjust the HOP Digital Data Separator,or just the controller card package.

ACT manufactures qualitycontroller card packages with low-cost and high-performance in mind.Even the first ACT HOP controllercard package we delivered toWestern Europe is still running like a

dream. So are our other deliveries.

Or, you can order fully assembled CRTterminals with an integrated 51/4"Winchester Hard Disk and controllercard package. Should you want a 51/4"floppy back-up, you canorder ourdual 5W' harddisk and floppycombination.

$1,250.

^^ (clnrtlo miant-irv* fnr fhP rnmnlpfp ACT ^W H3

Whatever you order, rememberthat our units feature simple,standard plug-in compatibility withyour zenith/Heath, TRS-80,* S-100 orSuperbrain* micro-computers. Justplug-it-in and turn-it-on.

Call ACT today for your 51/4" harddisk needs; we believe our productswill impress you and your computer.

Call (703) 471-9750.

American computerand TelecommunicationsCorporation

(single quantity) for the complete ACT 5V4" HardDisk controller card Package. Hard Disks, CRTTerminals, etc. are priced extra. Substantial OEMand dealer discounts are available.

^•TRS-80 is a trademark of RADIO SHACK, a division o£ Tandy CorporationSUPERBRAIN is a trademark of INTERTEC DATA SYSTEMS

Circle 18 on inquiry card.

11301 Sunset Hills RoadReston Virginia 22090(703) 471-9750

Listing 1 continued:

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SUBROUTINE PUSH(X$)

< S9 THEN 930

"STRING STACK OVERFLOW"

REM CALL POP(X$) TO GET ANSWER

GOSUB 1040

IF X$ <> "" THEN 800

NEXT HI

REM FAILURE

PRINT "No hypothesis can be confirmed.

GOTO 820

REM SUCCESS

PRINT "I conclude that ";Z$;H$(H1);"."

PRINT

PRINT "Restart or Quit (R or Q)";

INPUT C$

IF C$ = "R" THEN 640

IF C$ <> "Q" THEN 830

STOP

REMIF SIPRINTSTOP

51 = SI + 1S$(S1) - X$RETURN

REM SUBROUTINE PUSH(X)

IF S2 < S8 THEN 1010

PRINT "NUMBER STACK OVERFLOW"

STOP

52 = S2 + 1S(S2) = XRETURN

REM

REM SUBROUTINE P0P(X$)

IF SI > 0 THEN 1090

PRINT "STRING STACK UNDERFLOW"

STOP

X$ = S$(S1)

SI - SI - 1

RETURN

REM

REM

IF S2

PRINT

STOP

X » S(S2)

S2 = S2 - 1

RETURN

REM

SUBROUTINE POP(X)

> 0 THEN 1170

"NUMBER STACK UNDERFLOW

SUBROUTINE VERIFY(F1$, Y)

ATTEMPTS TO PROVE THAT FACT Fl$ IS TRUE

CALL RECALL TO SEE IF WE ALREADY KNOW Fl$

REM

REM

REM

F2$ = Fl$

GOSUB 1840

IF R2$ <> "" THEN 1760

REM Fl$ NOT CURRENTLY KNOWN

GOSUB 2100

REM ANSWER IS IN Q, WITH Q(0) THE COUNT

Q8 = Q(0)

IF Q8 > 0 THEN 1360

REM NO RULES; CALL ASK TO ASK THE USER

GOSUB 2320

IF Al$ = "" THEN 1790

GOTO 17 60

REM CHAIN BACKWARD THROUGH THE RULES RECURSIVELY

Ql = 1

REM PUSH NEEDED LOCAL VARIABLES

X$ = Fl$

GOSUB 880

X = Y

GOSUB 960

FOR Q2 = 1 TO Q8

X = Q(Q2)

GOSUB 960

NEXT Q2

X = Q8

GOSUB 960

X = Ql

GOSUB 960

CALL INTHEN TO FIND RULES THAT DEDUCE IT

ARE THERE ANY RULES?

Listing 1 continued on page 268

the development of expert systems:the exercise of building a knowledgebase for a problem area forces the ex-pert to think through the problem in aprecise and thorough manner. Theresulting codification benefits thebasic science itself. For example,models of mineral deposits have ap-peared for years in the literature ofeconomic geology, but these modelshave traditionally been expressed inEnglish prose, accompanied byschematic geological sketches andmaps. Such models are meaningful togeologists, but they are descriptiverather than predictive. Furthermore,many details are left unstated becausethe author assumes that the readerswill understand what is meant. Sincethe development of PROSPECTOR,there seems to be more interestamong geologists in developingmodels more precise than those of thepast.

We pay dearly for expertise whenwe need it, whether it's for fixing ahome appliance or for finding oil.Knowledge-based expert systems of-fer the potential of codifying anddisseminating expertise to those whodon't have it. In effect, knowledge-based expert systems offer the prom-ise of putting experts at everyone'sdisposal.

A Simple Rule-Based System

Most rule-based expert systems arelarge programs written in LISP, toobig for today's personal computers.However, it is possible to write asmall rule-based program that is bothentertaining and educational.

The BASIC program shown inlisting 1 implements a simple versionof the backward-chaining procedureused in MYCIN. This program isessentially a recoding of theDIAGNOSE program used byWinston and Horn in their book LISP(see reference 35) to explain rule-based systems, and includes their setof fifteen rules for identifyinganimals. The network formed bythese rules is depicted in figure 5.While these rules are too few and toosimple for serious use, you mighthave fun changing them and creating

Text continued on page 274

266 September 1981 © BYTE Publications Inc

Computer experts(the pros) usually have bigcomputer experience.That's why when they shopsystem software for Z80micros, they look forthe big system featuresthey're used to. And that'swhy they like Multi-UserOASIS. You will too.

DATA INTEGRITY: FILE &AUTOMATIC RECORD LOCKING

The biggest challengefor any multi-user systemis co-ordinating requestsfrom several usersto change the same recordat the same time.

Without properco-ordination, theconfusion and problemsof inaccurate or evendestroyed data can bestaggering.

Our File and AutomaticRecord Locking featuressolve these problems.

For example: normallyall users can view aparticular record at thesame time. But, if thatrecord is being updatedby one user, automaticrecord locking will deny allother users access to therecord until the up-date iscompleted. So recordsare always accurate,up-to-date and integrityis assured.

Pros demand file &automatic record locking.OASIS has it.

SYSTEM SECURITY:LOGON, PASSWORD& USER ACCOUNTING

Controlling who gets onyour system and what theydo once they're on it is theessence of system security.

Circle 292 on inquiry card.

(THEN COMPARE.)

Without this control,unauthorized users couldaccess your programs anddata and do what they like.A frightening prospectisn't it?

And multi-userscan multiply the problem.

But with the Logon,Password and PrivilegeLevel features of Multi-UserOASIS, a system managercan specify for each userwhich programs and filesmay be accessed —and forwhat purpose.

Security is furtherenhanced by UserAccounting—a feature thatlets you keep a historyof which user has beenlogged on, when andfor how long.

Pros insist on thesesecurity features.OASIS has them.

EFFICIENCY:RE-ENTRANT BASIC

A multi-user systemis often not even practicalon computers limitedto 64K memory.

OASIS Re-entrantBASIC makes it practical.

How?

Because all users use asingle run-time BASICmodule, to execute theircompiled programs, less

memory is needed. Evenif you have more than 64K,your pay-off is cost savingand more efficient useof all the memory you haveavailable —because itservices more users.

Sound like a pro feature?It is. And OASIS has it.

AND LOTS MORE...

Multi-User OASIS supportsas many as 16 terminalsand can run in as little as56K memory. Or, withbank switching, as muchas 784K.

Multi-Tasking lets eachuser run more than onejob at the same time.

And there's our BASIC-a compiler, interpreter anddebugger all in one.An OASIS exclusive.

Still more: Editor; Hard& Floppy Disk Support;Keyed (ISAM), Direct &Sequential Files; Mail-Box;Scheduler; Spooler;all from OASIS.

Our documentation isrecognized as some of thebest, most extensive, in theindustry. And, of course,there's plenty ofapplication software.

Put it all together and it'seasy to see why the realpros like OASIS. Join them.Send your order today.

MAKES MICROS RUN LIKE MINIS

OASIS IS AVAILABLE FOR

SYSTEMS: Alios: Compucorp. Cromemco:Delta Products: Digital Group: DigitalMicrosystems: Dynabyte: Godbout: IBC:Index: Intersystems; North Star: Onyx:SD Systems: TRS 80 Mod II; VectorGraphic: Vonmex

CONTROLLERS: Bell Controls: Cameo:Corvus. Konan: Micromation: Micropolis;Tarbell: Teletek; Thinkertoys: X Comp

Write for complete.

tree Application Software Directory

PLEASE SEND ME:

Product

OPERATING SYSTEM

(Includes:EXEC LanguageFile Management:User Accounting:Device Drivers;Print Spooler;General TextEditor: etc.)SINGLE-USERMULTI-USER

BASIC COMPILER/INTERPRETER/DEBUGGER

RE-ENTRANT BASIC

COMPILER/INTERPRETER/

DEBUGGER

DEVELOPMENT PACKAGE

(Macro Assembler;Linkage Editor;Debugger)

TEXT EDITOR &SCRIPT PROCESSOR

DIAGNOSTIC &CONVERSION UTILITIES

(Memory Test:Assembly Language:Converters: FileRecovery, Disk Test:File Copy tromother OS; etc.)

COMMUNICATIONSPACKAGE

(Terminal Emulator;File Send & Receive)

PACKAGE PRICE

(All of Above)

SINGLE-USER

MULTI-USER

FILE SORT

COBOL-ANSI '74

Price

with

Manual

SI50350

ManualOnly

S17.5017.50

Order OASIS from:

Phase One Systems, Inc.

7700 Edgewater Drive, Suite 830

Oakland, CA 94621

Telephone (415) 562-8085TWX 910-366-7139

NAME

STREET (NO BOX =)

CITY

.ZIP.

STATE

AMOUNT $

(Attach system description;

add S3 for shipping;

California residents add sales tax)

□ Check enclosed □ VISA

□ UPS C.O.D. D Mastercharge

Card Number

Expiration Date

Signature

BYTE September 1981 267

Circle 206 on Inquiry card.

Price/PerformanceBreakthrough!

777

^EpK

- "~5>l£ _ J!!!L.3lL.3li

I||I!U

Courtesy of DASOFT DESIGN SYSTEMS

Mauro MP-250B Prooc

The $775 pen plotter that gives

professional accuracy with

superb line quality!

Maura's design innovations make itpossible to produce a high quality, low costplotter that out-performs every other plotterof comparable price on the market today. Infact, its line quality matches that of plotterscosting $2,000 or more.

Proac draws with .005"/step resolutionand ±. 0.5% @ 17" degree of accuracy atspeeds of 2.5" per second or higher. Aunique multi-point paper drive helpsachieve this level of accuracy, makingProac suitable for a wide variety ofapplications.

Currently the MP-250B and the newerMP-300 are being used in Surveying, inDesign Automation for logic diagrams andprinted circuit layout, and in CAD draftingsystems. The MP-250B and MP-300 are theonly low cost plotters that have the speed,accuracy, repeatability, and line qualitynecessary to meet these demandingapplications. If your need is for professionalplotting consider one of our plotters or oneof our soon to be announced larger formatmodels.

Proac comes with full vector drivingsoftware for 8080, 6502, and 6800 basedcomputers. Interfaces are available forApple, and PET. With the addition oftheSIA250 intelligent interface, Proac becomescompatible with any computer.

Contact Mauro Engineering aboutcomplete information and specifications forMP-250B Proac and available software.

MAURO ENGINEERING

2220 Pack Trail

Mount Shasta, California 96067

Telephone 916 926-4406

268 September 1981 © BYTE Publications Inc

Listing 1 continued:

015100152001530015400155001560015700158001590016000161001620016300164001650016600167001680016900170001710017200173001740017500176001770O1780017900180001810018200183001840018500186001870018800189001900019100192001930019400195001960019700198001990020000201002020020300204002050020600207002080020900210002110021200213002140021500216002170021800219002200022100222002230022400225002260022700228002290

REM SETUP ARGUMENTS AND GOTO TRYRULE + (R1, Y)Rl - Q(Q1)

Y = 2GOTO 2840

REM POP AND SAVE THE ANSWER, AND POP THE LOCAL VARIABLES

GOSUB 1040

Xl$ = X$

GOSUB 1120

Ql - X

GOSUB 1120

Q8 - X

FOR Q2 = Q8 TO 1 STEP -1

GOSUB 1120

Q(Q2) = X

NEXT Q2

GOSUB 1120

Y = X

GOSUB 1040Fl$ = X$

IF Xl$ = "T" THEN 1760

REM RATS, RULE Rl DIDN'T WORK; TRY THE NEXT ONE

Ql = Ql + 1

IF Ql <= Q8 THEN 1380

REM CURSES, NONE OF THE RULES WORKED

GOTO 1790

REM SUCCESS

X$ = "T"

GOTO 1810

REM FAILURE

X$ = ""

REM PUSH THE ANSWER AND RETURN

GOSUB 880

ON Y GOTO 730,1550,2950,3300

REM

REM SUBROUTINE RECALL(F2$)

REM CHECKS TO SEE IF FACT F2$ HAS BEEN RECORDED

R2$ = ""

IF Fl =0 THEN 1940

FOR I - 1 TO Fl

IF F2$ = F$(I) THEN 1930

NEXT I

GOTO 1940

R2$ = F2$

RETURN

REM

REM SUBROUTINE REMEMBER(F2$)

REM RECORDS FACT F2$

Rl$ = ""

REM CALL RECALL TO SEE IF ALREADY STORED

GOSUB 1840

IF R2$ <> "" THEN 2090

REM ADD NEW FACT

IF Fl < F9 THEN 2060

PRINT "OUT OF ROOM FOR RECORDING FACTS"

STOP

Fl = Fl + 1

F$(F1) = F2S

Rl$ = F2$

RETURN

REM

REM SUBROUTINE INTHEN(F1$)

REM FINDS ALL THE RULES THAT HAVE FACT Fl$ AS A CONSEQUENT

Q(0) = 0

REM LOOP THROUGH THE RULES

FOR R3 = 1 TO R7

REM ■ FIND THE CONSEQUENTS OF RULE R3

R4 = R(R3) + 2

F2$ = R$(R4)

IE F2$ = "THEN" THEN 2220

R4 = R4 + 1

GOTO 2180

RgM LOOP THROUGH THE CONSEQUENTS

R4 = R4 + 1

F2$ = R$(R4)

IF F2$ = "STOP" THEN 2300

IF R$(R4+1) = "IF" THEN 2300

IF F2$ <> Fl$ THEN 2230

Q(0) = Q(0) + 1

Q(Q(0)) = R3 Listing 1 continued on page 270

Conies the revolution

in Apple word processing.

PowerText. From Beaman Porter.

Edit: occijst cipy Delete FiitVa iin

:l«tter/to Mr. Joe Sullivan, Jr.Jo* Sullivan 4 Associates, inc.1270 Avenue of the fimericasNew york. New York iee2e/sal Joe/closing Best regards.

Bruce J. BloomPresident

/oar I'ue produced this letter to youusing our APPLE computer and our newPowerText word processing system,/par PowerText is apso1utelyremarkaPle. There's simply nothingelse like it ... anywhere. -par Ididn't have to do any formatting 3tall. nil I did was enter the copyplus a few simple commands. Then Idid some editing, Pecause I changed mwind about a few words here arid thsr"/par PowerText did the rest. A pert.__

,.si.ng ° „ avst. to V°u *oc«»81 *

^""'e t M .Ww.VV«^'r- at all- £

not*i«* _ co do •# a ie,

l^1 a o b&r *• AV out

««« «old ,,4 tv>e ^at

«ot

d p

toce

Id OL 1 fOi

„,, h°l° „« toolvou «e.,,.ti»°8 „„ats-

Type this in.

Get this out!

Bat out a letter on your Apple's keyboard justas fast as you can.

Forget all about format. Keep on going.

As you go, just type in simple, shortcommands to identify the name and addresselement... the salutation... paragraphs... andsign-off.

Do your editing: Make any changes you like.

Then... tell PowerText to go to work.

In seconds a perfectly formatted letter startsrolling out of your printer. With every wordexactly where you want it.

And for an encore PowerText also addressesyour mailing envelope.

It's a true revolution in Apple word processingsoftware. New... from Beaman Porter.

Formats every document (lawlessly.

PowerText knows precisely how you like yourletters to look. And your memos. Your reports.Your presentations. Your manuscripts.

Every correspondence element, "TO" and"FROM" line, chapter heading, column ofstatistics, and paragraph... is exactly where youwant it.

Beautiful!

The editing power of PASCAL, the formattingpower of PowerText.

PowerText adds its own total document formatcontrol to the Pascal editor's exquisitecapabilities.

Result: you get perfect formatting... plus fullinsert, delete, and global search and replacecapabilities. In one remarkable system.

Plus... with a letter quality printer... theability to print in from 6 to 15 pitch.And you can use a variety of pitches within anydocument!

APPLE is a registered trademark ol Apple Computer, Inc. USCDPASCAL is a registered trademark ol UC, Regents. POWERTEXTis a registered trademark ol Beaman Porter, Inc.

Circle 37 on inquiry card.

Intelligent word processing decisions.

You never have to worry about page breaks,or winding up with "Yours truly" all by itself onpage 2 of your letter.

PowerText makes exactly the right decisionsabout all that for you.

And it automatically tracks your footnote orbibliography numbers.

Column formats are a snap.

PowerText accommodates up to 12 columnsper 132-character line. With individual linespacing for each column.

It lets you left- or right-justify—or center-each column separately. Or print any column inparagraph style. And there are no tab settings toset for columnar reports; PowerText does thearithmetic for you.

PowerText requires 48 K APPLE II or APPLE IIPLUS, two disk drives, and PASCAL languagesystem, plus a Qume, Diablo, or Epson printer.

FULL 5-YEAR WARRANTY!

PowerText has been proven with the mostdemanding tests... and texts... we could devise.It always works. If it should fail to perform asspecified ...for a full 5 years... send it back.We'll fix it at no charge.

Limited Time Introductory Offer.

The operating ease, scope, and sophisticationof PowerText go far beyond any other wordprocessing software... at any price.

Yet PowerText, plus its excellent Manual/Tutorial, are available now at the SpecialIntroductory Price of only $199. (Manual/Tutorialalone, only $25... deductible from the $199package price when you order the disk later.)

Available from selected dealers nationwide, ordirect from

&^ BEAMAN PORTER, INC.

/y[J High Performance Computer Products

Pleasant Ridge Road,(914) 967-3504

Harrison. NY 10528

BEAMAN PORTER, INC. B91

Pleasant Ridge Road, Harrison, NY 10528

□ Send complete PowerText system(s) (Disk

plus Manual/Tutorial) (a $199.

□ Send copies of the Manual/Tutorial only

@$25 (deductible from the $199 total system pricewhen I order the Disk later)

□ My check or money order for enclosed.

Or, bill to my:

□ Mastercard □ Visa(Mastercard only, list 4 digits above your name

Card No. _Signature.

Exp. Date. Date_

Name_Street.

City, State, Zip

i understand my PowerText Disk is warranted lor a full five years.Should it (ail to perform as specified, Beaman Porter, Inc. will fix itfor me at no charge.

BYTE September 1981 269

Circle 73 on inquiry card.

If you're looking for

the best pricesin the U.S.A. on

MICROCOMPUTERS

We have consistently offered theTRS-80 line at savings up to 20%. Youcan save up to $1500 by buyingfrom Computer Discount of America.

ATARI

MICROCOMPUTERS

®

We have the full line of ATARI per-sonal computers and systems.Model II

26-4002 64K. 1 disc $3385.00

Model III

26-1061 4K. Level I $ 610.00

26-1062 16K. Level III $ 845.00

26-1066 48K. Level II 2-drive/RS-232 $2115.00

Color Computer

26-3001 4K $ 329.00

26-3002 16K w/Ext. Basic $ 499.00

EPSON

MX70 Printer $ 375.00

MX80 Printer $ 485.00

MX80FT Printer $ 539.00

Our savings are as big on expansioninterfaces, printers, diskettes, AppleComputers, OKIDATA Microline,C-ITOH Starwriter, Lexicon Modems— everything for your computer.We have the largest inventory in theNortheast, and most models are instock, for immediate delivery.Our full price catalog or a pricequote is as near as your phone.

CALL TOLL FREE:800-526-5313

Computer

of America

COMPUTER DISCOUNT OF AMERICA. INC.15 Marshall Hill Road. West Milford MallWest Milford. New Jersey 07480In New Jersey Call 201-728-8080

270 September 1981 © BYTE Publications Inc

Listing 1 continued:

02300 NEXT R302310 RETURN

02320 REM

02330 REM SUBROUTINE ASK(F1$)

02340 REM ASKS THE USER ABOUT Fl$ AND EXPLAINS ITS REASON

02350 Al$ - ""

02360 REM HAVE WE ASKED THE USER ABOUT Fl$ BEFORE?

02370 IF Al - 0 THEN 2410

02380 FOR A2 = 1 TO Al

02390 IF Fl$ = A$(A2) THEN 2830

02400 NEXT A2

02410 REM WE HAVEN'T ASKED BEFORE. IF WE HAVE ROOM, LET'S ASK.

02420 IF Al < A9 THEN 2450

02430 PRINT "OUT OF ROOM FOR ASKED QUESTIONS"

02440 STOP

02450 Al = Al + 1

02460 A$(A1) = Fl$

02470 PRINT "Is this true: ";Z$;F1$;

02480 INPUT C$

02490 IF C$ = "Y" THEN 2790

02500 IF C$ = "N" THEN 2830

02510 IF C$ <> "W" THEN 2470

02520 REM THE USER WANTS TO KNOW WHY I ASKED

02530 REM ARE WE WORKING ON A RULE?

02540 IF Fl$ <> H$(H1) THEN 2590

02550 REM NO, Fl$ IS A TOP-LEVEL HYPOTHESIS

02560 PRINT "One of the possibilities is ";Z$;F1$

02570 PRINT "Unfortunately, I have no way to deduce this except to ask you."

02580 GOTO 2470

02590 REM YES. Fl$ IS A SUBGOAL. PRINT RULE Rl

02600 PRINT "I am trying to use Rule "jR$(R(Rl))

02610 R3 = R(R1) + 2

02620 IF R3 = R2 THEN 2670

02630 PRINT "I already know that:"

02640 PRINT Z$;R$(R3)

02650 R3 - R3 + 1

02660 IF R3 < R2 THEN 2640

02670 PRINT "IF:"

02680 PRINT Z$;R$(R3)

02690 R3 = R3 + 1

02 700 IF R$(R3) <> "THEN" THEN 2680

02710 PRINT "THEN:"

02720 R3 = R3 + 1

02730 PRINT Z$;R$(R3)

02740 R3 - R3 + 1

02750 IF R$(R3) - "STOP" THEN 2770

02760 IF R$(R3+1) <> "IF" THEN 2730

02770 PRINT

02780 GOTO 2470

02790 REM THE USER SAYS THAT Fl$ IS TRUE; CALL REMEMBER TO RECORD IT

02800 F2$ = Fl$

02810 GOSUB 1950

02820 Al$ = "T"

02830 RETURN

02840 REM

02850 REM SUBROUTINE TRYRULE+(R1, Y)

02860 REM TRIES TO APPLY RULE Rl

02870 REM PUSH NEEDED LOCAL VARIABLES

02880 X = Rl

02890 GOSUB 960

02900 X = Y

02910 GOSUB 960

02920 REM SETUP ARGUMENTS AND GOTO TESTIF+(R1, Y)

02930 Y = 3

02940 GOTO 3130

02950 REM POP THE RESULTS OF TESTIF+ AND RESTORE LOCAL VARIABLES

02960 GOSUB 1040

02970 GOSUB 1120

02980 Y = X

02990 GOSUB 1120

03000 Rl - X

03010 IF X$ = "" THEN 3080

03020 REM CALL USETHEN

03030 GOSUB 3460

03040 IF Ul? = "" THEN 3080

03050 REM SUCCESS

03060 X$ = "T"

03070 GOTO 3100

03080 REM FAILURE Listing 1 continued on page 272

\

Circle 370 on inquiry card.

COMPUTERS-TERMINALS-MODEMS!

MODEMS AND COUPLERS

Connect your Apple, TRS-80 or any other computer or terminal to the phone lines!

Penril

Penril300/1200

Penril 300/1200—Bell 212A style $799

Bell 212A style. 1200 baud and 300 baud. Manual origi-nate, auto-answer. Full duplex. RS232. Direct connectto phone lines via RJ11C standard extension phonevoice jack. 1 year warranty.

U.S. Robotics

USR-330A

Bell 103/113 style

USR-330D

Bell 103/113 style

USR-330D $339

Bell 103/113 style. 330 baud. Manual originate, auto-answer. Halt/full duplex. RS232.1 year warranty. Directconnect to phone lines via RJ11C standard extensionphone voice jack.

USR-330A $399

Same as USR-330D but includes auto-dial capability.

U.S. Robotics

The

Phone LinkAcousticModem

Bell 103/113 style $179

300 baud. Sleek, low profile. Originate and answer cap-ability. Half/full duplex. Self-test. RS232. Light displaysfor On, Carrier, Test, Send Data, Receive Data. 15 oz.

Perkin-Elmer Corporation

Bantam 550B .... $6941

Compact. Silent. Upper/lower |case. 80th col. wrap-around.Bell. Integrated numeric pad.Printer port. Transparentmode. Editing features.Tabbing.Bantam 550 E... $7551

Same as 550B plusseparate numeric key-pad and cursor direction Ikeys.

Bantam 550S $879

Same as 550E plus block mode. 8 function keys, andprotected fields, reverse video fields, half intensityfields, blinking fields.

550 Options

20mA Current Loop Interface $70

Non-Glare Screen $25

2nd page of memory (550S only).. $100

Digital Equipment Corporation

DECVT100

DEC VT100... $1668

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Listing 1 continued:

03090031000311003120031300314003150031600317003180031900320003210032200323003240032500326003270032800329003300033100332003330033400335003360033700338003390034000341003420034300344003450034600347003480034900350003510035200353003540035500356003570035800359003600036100362003630036400365003660036700368003690037000371003720037300374003750037600377003780037900380003810038200383003840038500386003870

X$ = ""

REM PUSH THE ANSWER AND RETURN

GOSUB 880

ON Y GOTO 730,1550,2950,3300

REM

REM SUBROUTINE TESTIF+(R1, Y)

REM CHECKS ANTECEDENTS TO SEE IF RULE Rl IS APPLICABLE

R2 = R(R1) + 2

F2$ = R$(R2)

IF F2$ = "THEN" THEN 3410

REM PUSH NEEDED LOCAL VARIABLES

X - Y

GOSUB 960

X = Rl

GOSUB 960

X = R2

GOSUB 960

REM SETUP ARGUMENTS AND GOTO VERIFY

Y = 4Fl$ = F2$GOTO 1200

REM POP ANSWER FROM VERIFY AND RESTORE LOCAL VARIABLES

GOSUB 1040

GOSUB 1120

R2 = X

GOSUB 1120

Rl = X

GOSUB 1120

Y = X

IF X$ = "" THEN 3430

R2 - R2 + 1

GOTO 3170

REM SUCCESS

X$ = "T"

REM PUSH THE ANSWER AND RETURN

GOSUB 880

ON Y GOTO 730,1550,2950,3300

REM.

REM SUBROUTINE USETHEN(Rl)

REM APPLIES RULE Rl AND PRINTS NEW DEDUCTIONS

Ul$ = ""

REM FIND THE CONSEQUENTS

R2 = R(R1) + 2

F2$ - R$(R2)

IF F2$ = "THEN" THEN 3560

R2 - R2 + 1

GOTO 3520

REM LOOP THROUGH CONSEQUENTS

R2 - R2 + 1

F2$ - R$(R2)

IF F2$ = "STOP" THEN 3670

IF RS(R2+1) - "IF" THEN 36 70

REM CALL REMEMBER TO ASSERT THE CONSEQUENT

GOSUB 1950

IF Rl$ - "" THEN 3570

PRINT "Rule " ;R$ (R (Rl)); " deduces ";Z$;F2$

Ul$- "T"

GOTO 3570

RETURN

REM

REM SUBROUTINE LOADRULES

REM INITIALIZES THE RULE ARRAYS R$ AND R WITH THE RULE DATA

READ Z$

R7 = 0

R8 - 0

IF R8 < R9 THEN 3770

PRINT "OUT OF ROOM FOR RULES"

STOP

REM READ NEXT RULE INTO R$

REM FORMAT: <name> IF <ant>

R8 = R8 + 1

READ R$(R8)

IF R$(R8) <> "IF" THEN 3840

R7 = R7 + 1

R(R7) = R8 - 1

IF R$(R8) <> "STOP" THEN 3740

RETURN

REM RULE DATA

DATA "ANIMAL "

<ant> THEN <con> ... <con>

Listing 1 continued on page 274

272 September 1981 © BYTE Publications Inc

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BYTE September 1981 273

Listing 1 continued:

038800389003900039100392003930039400395003960039700398003990040000401004020040300404004050040600407004080040900410004110041200413004140041500416004170041800419004200042100422004230042400425004260

DATA "R1","IF","HAS HAIR","THEN","IS MAMMAL"

DATA "R2","IF","GIVES MILK","THEN ,"IS MAMMAL"

DATA "R3","IF","HAS FEATHERS","THEN","IS BIRD"

DATA "R4","IF","FLIES","LAYS EGGS","THEN","IS BIRD"

DATA "R5","IF","EATS MEAT","THEN","IS CARNIVORE"

DATA "R6","IF","HAS POINTED TEETH","HAS CLAWS","HAS FORWARD EYES"

DATA "THEN","IS CARNIVORE"

DATA "R7","IF","IS MAMMAL"."HAS HOOFS","THEN","IS UNGULATE"

DATA "R8","IF","IS MAMMAL","CHEWS CUD","THEN","IS UNGULATE"

DATADATADATADATADATADATADATA

"R9","IF","IS MAMMAL","IS CARNIVORE","HAS TAWNY COLOR"

"HAS DARK SPOTS","THEN","IS CHEETAH""R10","IF","IS MAMMAL","IS CARNIVORE","HAS TAWNY COLOR"

"HAS BLACK STRIPES","THEN","IS TIGER"

'R11","IF","IS UNGULATE","HAS LONG NECK","HAS LONG LEGS""HAS DARK SPOTS","THEN","IS GIRAFFE"

,R12","IF","IS UNGULATE","HAS BLACK STRIPES","THEN","IS ZEBRA"DATA "R13","IF","IS BIRD","DOES NOT FLY","HAS LONG NECK"DATA "IS BLACK AND WHITE","THEN","IS OSTRICH"

DATA "R14","IF","IS BIRD","DOES NOT FLY","SWIMS","IS BLACK AND WHITE"DATA "THEN","IS PENGUIN"

DATA "R15"."IF","IS BIRD","FLIES WELL","THEN","IS ALBATROSS"DATA "STOP"

REM

REM SUBROUTINE LOADHYPOTHESES

REM INITIALIZES THE HYPOTHESIS ARRAY H$ WITH HYPOTHESIS DATA

H8 - 0

IF H8 < H9 THEN 4170

PRINT "OUT OF ROOM FOR HYPOTHESES"

STOP

REM READ NEXT HYPOTHESIS

H8 = H8 + 1

READ H$(H8)

IF H$(H8) <> "STOP" THEN 4180

H8 = H8 - 1

RETURN

REM HYPOTHESIS DATA

DATA "IS ALBATROSS","IS PENGUIN","IS OSTRICH","IS ZEBRA"

DATA "IS GIRAFFE","IS TIGER","IS CHEETAH","STOP"

END

Text continued from page 266:

new ones. Moreover, by replacingthese rules with rules for identifying,say, birds or flowers, you can use thesame program for many other iden-tification tasks. A more practical ap-plication might be a set of rules fordiagnosing what is at fault in amalfunctioning toilet or washingmachine.

The rules themselves appear in theDATA statements in lines 3880through 4080. Each rule has the form:

<name>,"IF", <a>, ... ,<a>,"THEN",<c> <c>

For example, "R7","IF","IS MAM-MAL", "HAS HOOFS", "THEN", "ISUNGULATE". The name of the rulecan be any convenient string. Theantecedents <a> and consequents<c> are strings that correspond topropositions about the animal andthey may be true or false. If all theantecedents are found to be true, theprogram can use the rule to assert thetruth of all the consequents. The rulesare terminated by the string "STOP".In addition to the rules, the pro-

CHEETAH

GIRAFFE

ZEBRA

Trii

(AND)

7YN

LONGLEGS

BLACKSTRIPES

OSTRICH

n\

LONGNECK

PENGUIN

FEATHERS

SWIMS

FLIES LAYS EGGS

Figure 5: A sample network for a simple rule-based system. Boxes represent assertions, circles represent ways of combining asser-tions, and the labels Rl, R2, etc, identify rules. The diagram corresponds to the rules given in lines 3880 through 4080 of listing 1.

274 September 1981 © BYTE Publications Inc

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gram uses a set of hypotheses, whichappear in the DATA statements inlines 4240 through 4250. In this case,the hypotheses are that the animal iseither an albatross, a penguin, anostrich, a zebra, a giraffe, a tiger, or acheetah. The goal of the program is toestablish the truth of one of thesehypotheses.

The program operates by trying thehypotheses one at a time. For eachhypothesis, the program scans the listof rules to see if the hypothesis can bededuced. If so, the antecedents for therelevant rules become new sub-hypotheses to be established, and theprogram looks for rules for deducingthese antecedents. The programchains backward through the rulesuntil no deductions can be made, atwhich point the program asks theuser if the subhypothesis it is workingon is true.

The core subroutine that im-plements this strategy is calledVERIFY (see lines 1210 through1830). VERIFY tries to determine if its

argument Fl$ is true. The argumentFl$ represents a hypothesis or sub-hypothesis. If the truth of Fl$ hasalready been recorded, VERIFYreturns immediately. If there are norules for deducing Fl$, and if VERIFYhas not asked the user about Fl$before, it asks. Otherwise, VERIFYapplies TRYRULE+ to each of therules in turn until it either meets withsuccess or exhausts the rules.

The only thing that complicates thecoding of this simple strategy is thatTRYRULE+ uses TESTIF+ to see ifall the antecedents for the rule aretrue, and TESTIF+ checks theantecedents by calling VERIFY. Thus,VERIFY is recursive, and BASIC doesnot support recursion. Therefore, allthe reentrant subroutines must ex-plicitly save their local variables onpush-down stacks before transferringcontrol to one another, restoringthose values upon return. To see onereason why AI workers prefer LISP,which takes care of all this bookkeep-ing automatically, you need only

Listing 2: A sample run of the identification program shown in listing 1, The programasks questions and makes deductions, when possible, based on the answers. The pro-gram always cites the rule used to make a deduction.

to try to establish one of the

Hello.

I will use my 15 rulesfollowing 7 hypothesesANIMAL IS ALBATROSSANIMAL IS PENGUINANIMAL IS OSTRICHANIMAL IS ZEBRAANIMAL IS GIRAFFEANIMAL IS TIGERANIMAL IS CHEETAH

Please answer my questions with Y (yes), N (no), or W (why).

Is this true ANIMAL HAS FEATHERS ?N

Is this true: ANIMAL FLIES ?N

Is this true: ANIMAL HAS HAIR ?Y

Rule Rl deduces ANIMAL IS MAMMAL

Is this true: ANIMAL HAS HOOFS ?N

Is this true: ANIMAL CHEWS CUD ?N

Is this true: ANIMAL EATS MEAT ?Y

Rule R5 deduces ANIMAL IS CARNIVORE

Is this true: ANIMAL HAS TAWNY COLOR ?Y

Is this true: ANIMAL HAS BLACK STRIPES ?W

I am trying to use Rule RIO

I already know that:

ANIMAL IS MAMMAL

ANIMAL IS CARNIVORE

ANIMAL HAS TAWNY COLOR

IF:

ANIMAL HAS BLACK STRIPES

THEN.

ANIMAL IS TIGER

Is this true: ANIMAL HAS BLACK STRIPES ?NIs this true: ANIMAL HAS DARK SPOTS ?YRule R9 deduces ANIMAL IS CHEETAHI conclude that ANIMAL IS CHEETAH.

glance at the simpler version of thissame program in Winston and Horn'sbook.

Pascal would be a better languagethan BASIC for our program becausePascal supports recursion and allowsuser-defined data structures (eg: usingrecords and the type statement), aswell as providing an easy-to-understand block structure. We choseto write this program in BASIC ratherthan Pascal because more personalcomputers have BASIC. (We hopeour use of BASIC will not contributeto the perpetuation of this condition!)

Listing 2 shows an example of thedialogue when the user was thinkingof a cheetah. A look at the rulesshows why the program asked thequestions it did. Working the firsthypothesis (albatross), the programtried to use rule Rl5, which set up thesubgoal of seeing if the animal was abird. Rules R3 and R4 were relevant,so the program tried rule R3 andasked if the animal had feathers. Theprogram soon ruled out the possibili-ty of a bird, so it skipped the penguinand ostrich hypotheses. Working onrule Rl2 for the zebra hypothesis, onrule Rll for the ungulate sub-hypothesis, and on rule Rl for themammal sub-subhypothesis, the pro-gram successively established that theanimal was a mammal, was not anungulate, and was a carnivore calleda cheetah.

It is worth noting that thebackward-chaining strategy is dif-ferent from the classical divide-and-conquer approach used in binarysearch. With four well-chosen ques-tions, it is possible to make the one-out-of-fifteen decision that requirednine questions in this example. Beforeconcluding that rule-based programsare hopelessly inefficient, you shouldnote that the rules do make use ofsubclasses and sub-subclasses, muchas is done in binary search. Thus,once it is learned that the animal isnot a bird, for example, no morequestions concerning birds will beasked. The main difference is that thisparticular program does not askdirectly if the animal is a bird, butrather asks for primitive observationsthat allow "birdness" to be deduced.

276 September 1981 © BYTE Publications Inc

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BYTE September 1981 177

To gain efficiency, you might wantto change the program so it will askthe user about intermediatehypotheses, resorting to deductiononly when the user gives a "don'tknow" response. This illustrates howthe rule-based approach actually pro-vides great flexibility by separatingthe control strategy (as implementedin VERIFY) from the knowledge base(as represented by the rules).

The rule-based identificationsystem just described is at best a toy.Although this system illustrates theimportant principle of the separationof the rule base from the general-

reasoning program, the system lacksmany important features included instate-of-the-art research systems.Among the features present in moststate-of-the-art knowledge-basedsystems, but lacking in our toy pro-gram, are the following:

• immediate propagation of in-ferences

• negative inferences

• plausible inference's ability to han-dle mutually exclusive categories

• contextual constraints

• degrees of certainty in user'sanswers

Tune tip your LA36

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• Optional APL character setOver 5,000 DS120 units are now being used by customers ranging fromthe Fortune 500 to personal computing enthusiasts. In numerous instal-lations, entire networks of terminals have been upgraded to take advan-tage of today's higher speed datacommunications services. LSI -- ...tm_,^,,.microprocessor electronics ^'iiEfsfoand strict quality control en-sure dependable performancefor years to come. When ser-vice is required, we willrespond promptly and effec-tively. Best of all, we can de-liver immediately throughour nationwide network ofdistributors. Just give us acall for all the details.

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• information volunteered by the user

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But toys are fun, and are often ef-fective teachers. Enjoy. ■

References

1. Balzer, R, L D Erman, P London, and CWilliams. "HEARSAY-HI: A Domain-Independent Framework for ExpertSystems." Proceedings of the FirstAnnual National Conference on ArtificialIntelligence, 1980, pages 108 through110.

2. Barstow, D R. "An Experiment inKnowledge-based Automatic Program-ming." Artificial Intelligence, volume 12,August 1979, pages 7 through 119.

3. Bennett, J S and R S Engelmore."SACON: A Knowledge-Based Consul-tant for Structural Analysis." Pro-ceedings of the Sixth International JointConference on Artificial Intelligence,August 20-23, 1979, pages 47 through49.

4. Brown, J S, R R Burton, and A G Bell."SOPHIE: A Sophisticated InstructionalEnvironment for Teaching ElectronicTroubleshooting (An Example of Al inCAI)." Final Report, ContractF41609-73-C-006, Bolt, Beranek, andNewman Inc, Cambridge MA, March1974.

5. Buchanan, B G and T M Mitchell."Model-Directed Learning of ProductionRules." Pattern-Directed InferenceSystems, D A Waterman and F Hayes-Roth (editors), New York: AcademicPress, 1978, pages 297 through 312.

6. Bundy, A, et al. "Solving MechanicsProblems Using Meta-Level Inference."Expert Systems in the MicroelectronicAge, D Michie (editor), Edinburgh: Edin-burgh University Press, 1979, pages 50through 64.

7. Carbonell, J R. "Al in CAI: An Artificial-Intelligence Approach to Computer-Aided Instruction." IEEE Transactionson Man-Machine Systems, volumeMMS-11, December 1970, pages 190through 202.

8. Clancey, W J, E H Shortliffe, and B GBuchanan. "Intelligent Computer-AidedInstruction for Medical Diagnosis." Pro-ceedings of the 3rd Symposium on Com-puter Application in Medical Care, 1979,pages 175 through 183.

9. Davis, R. "Interactive Transfer of Exper-tise: Acquisition of New InferenceRules." Artificial Intelligence, volume12, August 1979, pages 121 through157.

10. Davis, R and J King. "An Overview ofProduction Systems." MachineIntelligence 8, E W Elcock and D Michie(editors), New York: Wiley, 1976, pages300 through 332.

11. Duda, R O, J G Gaschnig, and P E Hart."Model Design in the Prospector Con-

278 September 1981 © BYTE Publications Inc

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For the name of your nearestsupplier, write BASF Systems,Crosby Drive, Bedford,MA 01730, or call 617-271-4030.

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MACRO 80 by Microsoft

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EDIT 80 by Microsoft

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sultant System for Mineral Exploration."Expert Systems in the MicroelectronicAge, D Michie (editor), Edinburgh: Edin-burgh University Press, pages 153through 167.

12. Fagan, L, J Kunz, E A Feigenbaum, andJ Osborn. "Representation of DynamicClinical Knowledge: Measurement Inter-pretation in the Intensive Care Unit."Proceedings of the Sixth InternationalJoint Conference on ArtificialIntelligence, August 20-23, 1979, pages260 through 262.

13. Feigenbaum, E A. "The Art of ArtificialIntelligence—Themes and Case Studiesof Knowledge Engineering." AFIPS Con-ference Proceedings, volume 47, June1978, pages 227 through 240; also in Ex-pert Systems in the MicroelectronicAge, D Michie (editor), Edinburgh: Edin-burgh University Press, 1979, pages 3through 25.

14. Feigenbaum, E A, B G Buchanan, and JLederberg. "On Generality and ProblemSolving: A Case Study Using The DEN-DRAL Program." Machine Intelligence6, B Meltzer and D Michie (editors), NewYork: American Elsevier, 1971, pages165 through 190.

15. Gaschnig, J G. "Development ofUranium Exploration Models for the Pro-spector Consultant System." FinalReport, SRI Project 7856, ArtificialIntelligence Center, SRI International,Menlo Park CA, March 1980.

16. Gelernter, H L, etal. "Empirical Explora-tions of SYNCHEM." Science,September 9, 1977, pages 1041 through1049.

17. Goldberg, R and S M Weiss. "An Experi-mental Transformation of a Large ExpertSystem Knowledge-Base." WorkingPaper, Department of ComputerScience, Rutgers University, NewBrunswick NJ, March 1980.

18. Kulikowski, C A. "Artificial IntelligenceMethods and Systems for Medical Con-sultation." IEEE Transactions on PatternAnalysis and Machine Intelligence,volume PAMI-2, September 1980, pages464 through 476.

19. Lesser, V R and L D Erman. "ARetrospective View of the HEARSAY-IIArchitecture." Proceedings of the FifthInternational Joint Conference on Artifi-cial Intelligence, August 22-25, 1977,pages 790 through 800.

20. McDermott, J. "R1: An Expert in theComputer Systems Domain." Pro-ceedings of the First Annual NationalConference on Artificial Intelligence,1980, pages 269 through 271.

21. Newell, A and H A Simon. "GPS, A Pro-gram that Simulates Human Thought."Computers and Thought, E A Feigen-baum and J A Feldman (editors), NewYork: McGraw-Hill, 1963.

22. Newell, A and H A Simon. Human Prob-lem Solving. Englewood Cliffs NJ:Prentice-Hall, 1972.

23. Nii, H P and E A Feigenbaum. "Rule-

280 September 1981 © BYTE Publications Inc

Circle 222 on inquiry card.

Based Understanding of Signals."Pattern-Directed Inference Systems, DA Waterman and F Hayes-Roth (editors),New York: Academic Press, 1978,pages 483 through 501.

24. Pauker, S G, G A Gorry, J P Kassirer,and W B Schwartz. "Towards theSimulation of Clinical Cognition."American Journal of Medicine, volume60, June 1976, pages 981 through 996.

25. Pople, H E, Jr, ef a/. "DIALOG: A Modelof Diagnostic Logic for InternalMedicine." Proceedings of the FourthInternational Joint Conference on Artifi-cial Intelligence, September 1975,pages 848 through 855.

26. Reboh, R. "The Knowledge AcquisitionSystem." "A Computer-Based Consul-tant for Mineral Exploration," R 0 Duda,et a/, Final Report, SRI Project 6415,Artificial Intelligence Center, SRI Inter-national, Menlo Park CA, September1979.

27. Shortliffe, E H. Computer Based MedicalConsultations: MYCIN. New York:Elsevier, 1976.

28. Stallman, R M and G J Sussman. "For-ward Reasoning and Dependency-Directed Backtracking in a System forComputer-Aided Circuit Analysis." Artifi-cial Intelligence, volume 9, 1977, pages135 through 196.

29. Stefik, M J. "Inferring DNA Structuresfrom Segmentation Data." ArtificialIntelligence, volume 11, August 1978,pages 85 through 114.

30. van Melle, W. "A Domain-IndependentProduction-Rule System for Consulta-tion Programs." Proceedings of theSixth International Joint Conference onArtificial Intelligence, August 20-23,1979, pages 923 through 925.

31. Waterman, D A. "User-OrientedSystems for Capturing Expertise: A Rule-Based Approach." Expert Systems inthe Microelectronic Age, D Michie(editor), Edinburgh: Edinburgh UniversityPress, 1979, pages 26 through 34.

32. Waterman, D A and F Hayes-Roth.Pattern-Directed Inference Systems.New York: Academic Press, 1978.

33. Weiss, S M and C A Kulikowski. "EX-PERT: A System for Developing Con-sultation Models." Proceedings of theSixth International Joint Conference onArtificial Intelligence, August 20-23,1979, pages 942 through 947.

34. Weiss, S M, C A Kulikowski, and A Safir."Glaucoma Consultation by Computer."Computers in Biology and Medicine,volume 8, 1978, pages 25 through 40.

35. Winston, P H and B K P Horn. LISP.Reading MA: Addison-Wesley, 1981,chapter 18.

36. Wipke, W T. "Computer Planning ofResearch in Organic Chemistry." Com-puters in Chemical Education andResearch, E V Ludena, N H Sabelli, andA C Wahl (editors), New York: PlenumPress, 1976, pages 381 through 391.

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September 1981 © BYTE Publications Inc 281

Print neatlyso we know

where to send\our check.

282 BYTE September 1981

Buying new software is the pits,isn't it?

You read an ad and it soundsterrific, so you ask around, then buythe manual.

So far, so good —so you springseveral hundred dollars for thepackage.

And it does exactly what theysaid. But to get exactly what youwant, you're going to have to changethe way you run your business. Orgo through so much hassle thatyou're not sure it's worth it.

So you grit your teeth and suffer,or put it on a shelf to gather dust.

Sounds familiar, doesn't it?

But there is at least one knownexception: an exceptional DBMScalled dBASE II.

For database fans, an offeryou shouldn't refuse.

dBASE II is the only high-performance relational DatabaseManagement System for micros.And it's the only DBMS that canhelp you get the DBMS that's rightfor you, no matter which DBMSyou may want. Here's how:

If you have a 48k micro withCP/M, send us its model numberand the size of your drives alongwith $700 (CP/M 86 version soon —call if you can't wait).

We'll send you a copy of dBASE IIthat you can run on your system,solving your problems your way,for 30 days. Then just send every-thing back and we'll return yourmoney, no questions asked.

During that 30 days, you can findout how much a real databasemanagement system can do for you.How it will affect your operations.Exactly what you want done. Andprecisely how you want to do it.

Then even if you go for someother system, you'll be an informedbuyer.

And it never hurts to know whatyou're doing.

IBM just caught up.So can you.

With dBASE II, you'll get thesame kind of system for your microthat IBM introduced a few monthsago for their mainframes.

It's a relational DBMS, and thatmakes it different from any othermicro system you've ever seen.

In a relational database, the datais organized as simple tables, withrecords as the rows and the datafields as the columns, much like yourdata is organized now. Data rela-tions are logical, so that you canzero in on the specific informationyou want without knowing a thingabout the pre-defined sets, pointersor other cumbersome structures ofhierarchal and network DBMS's.

And unlike file managementsystems, dBASE II gives you pro-gram and data independence. Youcan change your database structurewithout re-entering your data andwithout reprogramming, or changesome or all of your programs with-out touching your database. Andthe same database can be used forany number of different applications.

dBASE II is a stand-aloneapplications developmentsystem.

You don't need an extra supportlanguage, because dBASE II comeswith its own Applications Devel-opment Language (ADL). With ADL,you can use simple English-likestatements to manipulate your data,or use built-in structured constructsto prepare sophisticated applica-tions packages. It's simple and easyto use, yet extremely powerful.

You create a new database andstart using it in a minute or less.Just type CREATE, then respond tosystem prompts to name the file anddefine the fields. Now enter the data.

Add data to an existing databaseinstantly, whether your file has

AshtonTate

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10 records or 10,000 records, bytyping APPEND, then entering theinformation.

UPDATE, MODIFY, JOIN andREPLACE whole databases orindividual records and characters.

Add or delete fields in your data-base structure without re-enteringall your data.

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Do automatic calculations onfields, records and databases with afew keystrokes.

Organize months' worth of datain minutes with REPORT (printingoptional), and get your reportstoday instead of tomorrow. Usethe built-in SORT, with single ormultiple keys. Or INDEX yourdata, then FIND it in seconds, evenwith floppies.

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You'll wonder how youmanaged without it.

dBASE II is the most powerful,easiest to use DBMS you can get fora micro.

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What have you got to lose? Weeven provide the label so you cansend it back.

Ashton-Tate, 3600 Wilshire Blvd.,Suite 1510, Los Angeles, CA 90010.(213) 666-4409.

Circle 31 on inquiry card.

BYTE September 1981 283

The Atari Tutorial

Part 1: The Display List

Chris Crawford

1272 Borregas Ave

Sunnyvale CA 94086

Editor's Note: Although I have always considered myself an "Apple person"(I have a disk-based Apple II at home), it was exciting to attend a two-dayseminar for prospective Atari programmers given by Chris Crawford, LaneWinner, and Mike Ekberg, all of Atari Inc. Once I learned about the inter-nal structure of the Atari 400 and 800 computers, I realized the tremendouspotential these machines have.

We at BYTE are proud to present "The Atari Tutorial," a series of articleswritten by members of the Atari staff. The subjects include: the display list,graphics indirection and character sets, player-missile graphics, display-listinterrupts, scrolling, and Atari BASIC. This series of articles is adaptedfrom De Re Atari, a forthcoming book on the internal structure of Ataricomputers, to be published in December 1981 by Atari Inc.

This first article, which is on display lists, is by Chris Crawford, whowith Lane Winner coauthored the article "An Introduction to AtariGraphics," which we published in the January 1981 BYTE, page 18. "TheAtari Tutorial" will cover in greater detail many of the interesting pointsonly mentioned in the first article. We hope you enjoy the series....GW

The Atari personal-computersystem is a second-generation per-sonal computer. First and foremost, itis a consumer computer. The entirethrust of its design is to make the con-sumer comfortable with the com-puter. This consumer orientationreveals itself in many ways. First, theconsumer is protected from mistakesby items such as keystone-shapedconnectors that cannot be inserted thewrong way, a power interlock thatturns the computer off when internalelectronics are exposed, and a pair ofplastic shields protecting the systemreset key. Second, the machine has agreat deal of graphics power; peoplegenerally respond to pictures muchmore readily than to text. Third, themachine has good sound capabilities;again, people normally respond to

This article appears in slightly different formin De Re Atari, a book published by Atari Inc,and is reproduced with its express permission.

direct sensory input better than to in-direct textual messages. Finally, thecomputer has joysticks and paddlesfor more direct tactile input than ispossible with keyboards. The point isnot that the Atari personal-computersystem has a lot of features, butrather that the features are all part ofa consistent design philosophy aimedat the consumer. The designer whodoes not appreciate this fundamentalfact will be working against the grainof the system.

The internal layout of the Atari 400and 800 computers (which are elec-trically equivalent to each other) isvery different from that of othersystems. They do have a micro-processor (a 6502), RAM (random-access read/write memory), ROM(read-only memory), and a PIA(peripheral interface adapter).However, they also have threespecial-purpose LSI (large-scale in-tegration) devices known as ANTIC,

POKEY, and CTIA. These deviceswere designed by Atari engineersprimarily to take much of the burdenof housekeeping from the 6502, free-ing the 6502 to concentrate on com-putations. While they were at it, theydesigned a great deal of power intothese devices. Each is almost as big (interms of silicon area) as a 6502, so thethree of them together provide atremendous amount of power.Mastering the Atari 400/800 isprimarily a matter of mastering thesethree chips, a task we hope will beaided by this series of tutorial articles.

Principles of Television Display

In order to understand the graphicscapabilities of the Atari personal-computer system, you must firstunderstand the rudiments of how atelevision set works. Television setsuse a raster-scan display system. Anelectron beam is generated at the rearof the television tube and shot towardthe screen. Along the way, it passesbetween sets of horizontal and ver-tical coils or plates that, if energized,can deflect the beam to make it strikeany point on the screen. The elec-tronics inside the television set causethe beam to sweep across the screenin a regular fashion. The beam's in-tensity can be controlled: if you makethe beam more intense, the spot beingstruck on the screen glows brightly; ifyou make it less intense, the spotglows dimly or not at all.

The beam starts at the top left cor-ner of the screen and traces horizon-tally across the screen. As it sweepsacross the screen, the changes in in-tensity paint an image on the screen.When the beam reaches the right edgeof the screen, it is turned off, brought

284 September 1981 © BYTE Publications Inc

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BYTE September 1981 285

back to the left side of the screen, andmoved down a notch. It then turnsback on and sweeps across the screenagain. This process is repeated for 262sweeps across the screen. (There ac-tually are 525 sweeps across thescreen in an alternating systemknown as interlace. I will ignore in-terlace and act as if the television hasonly 262 lines.) These 262 lines fill thescreen from top to bottom. At thebottom of the screen (after the 262ndline is drawn), the electron beam isturned off and returned to the upperleft corner of the screen. Then it startsthe cycle over again. This entire cyclehappens sixty times a second.

Now for some jargon: a single traceof the beam across the screen is calleda horizontal scan line. A horizontalscan line is the fundamental unit ofmeasurement of vertical distance onthe screen. You state the height of animage by specifying the number ofhorizontal scan lines it spans. Theperiod during which the beam returnsfrom the right edge to the left edge is

called the horizontal blank. Theperiod during which the beam returnsfrom the bottom to the top of thescreen is called the vertical blank. Theentire process of drawing a screentakes 16,684 /is. The vertical-blankperiod is about 1400 /is. The horizon-tal blank takes 14 /is, while a singlehorizontal scan line takes 64 /xs.

Most television sets are designedwith overscan; they spread the imageout so the edges of the picture are offthe edge of the television tube. Thisguarantees that you have no unsight-ly borders in your picture. It is verybad for computers, though, becausescreen information that is off the edgeof the picture does you no good. Forthis reason, the picture the computerputs out must be somewhat smallerthan what the television cantheoretically display. For this reason,only 192 horizontal scan lines arenormally used by the Atari display.Thus, the normal limit of resolutionof a television set used with the Atari400/800 is 192 pixels (or picture

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elements) vertically. (Of course, acolor monitor can do much betterthan that.)

The standard unit of horizontaldistance is the color clock. Youspecify the width of an image bystating how many color clocks wide itis. There are 228 color clocks in asingle horizontal scan line, with amaximum of 176 actually visible.Thus, the ultimate limit for full colorhorizontal resolution with a standardcolor television is 176 pixels. With thecomputer, you can go even finer andcontrol individual half-clocks. Thisgives a horizontal resolution or 352pixels. However, use of this featureproduces interesting color effectsknown as color artifacts. Color ar-tifacts can be a nuisance if they arenot desired; they can be a boon to theprogrammer who desires additionalcolor and is not fazed by their restric-tions.

Microcomputer Displays

The fundamental problem anymicrocomputer has in using a raster-scan television for display purposes isthat the television display is adynamic process. Because of this, thetelevision does not remember the im-age. Consequently, the computermust remember the screen image andconstantly send a signal to the televi-sion telling it what to display. Thisprocess of sending information to thetelevision is a continuous process re-quiring full-time attention. For thisreason, most microcomputers havespecial hardware circuits that handlethe television. The basic arrangementis the same on virtually all systems:

microprocessor — screen RAM —video hardware — TV screen

The microprocessor writes infor-mation to the screen RAM area thatholds the screen data. The videohardware is constantly accessing thisRAM area, getting screen data andconverting them into televisionsignals. These signals go to the televi-sion, which then displays the infor-mation. The screen memory ismapped onto the screen in the sameorder in which it is stored. That is,the first byte in the screen memory

286 September 1981 © BYTE Publications Inc

Circle 166 on inquiry card.

Unique accessories to PET/CBM

add more power

Software

PET-FORTH

A unique, extensible program-ming language that in many caseshas cut program development timeto a fraction of the normal. FORTHallows you to program any type ofapplication, thanks to its extensiblenature. FORTH programs are modu-lar, structured, extremely fast, andcompact. PET-FORTH is a full, ex-tended, standard FORTH, and inclu-des a virtual memory facility, an inter-preter and compiler, a resident editor,as well as a resident macro assembler,all which fits in 8.5K - simultaneously.A comprehensive manual of more than 320 pages, which also is anexhaustive tutorial, is included. For production purposes we cansupply a special Target Compiler, that will produce code suitable forplacement in ROM, enabling you to write programs for control of digi-tal machines etc. We use FORTH ourselves for business, data baseand process control applications. PET-FORTH includes a life-timeguarantee. For 8032 only.

Price:

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including manualPET-FORTH,only manualTarget compilerPET-FORTH

$ 390$ 40$1000

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A program that turns your PET/CBM8032 into an intelligent terminal. Sup-ports three different interfaces: the PET-COM. the SCIP or the CBM 8010acoustic coupler. You may communi-cate at up to 9600 baud, with selectableframing and parity. PET-TERM will alsotranslate and transmit Word-Pro files.Data may be printed on the printer orsaved on disk PET-TERM includes a lifetime guarantee.

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This IEEE => Centronics interface is es-pecially constructed for the PET. It is fullyaddressable and translates from PET-ASCII to Standard ASCII in two differentmodes, corresponding to PET's graphic and j flj iupper/lowercase modes. This is available r^*AlB' »

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Country specific Character Generator

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By using this board you can have Greek,French, German, or any other specialcharacters in your printer, at a very low costIt is already used in all Nordic countries,and several other countries haverequested it. prjce; $ 4Q

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Datatronic AB is since 1978 sole Swedish distributor of the Commodore computer product line, and is now market leading inmicrocomputer technology in Scandinavia. Datatronic AB has a long experience in both hardware and software; todayDatatronic has used more than 150.000 man-hours in software and hardware development for the PET. All non-Commodoreproducts are produced and tested in-house. The Datatronic-group, which is the fastest growing electronics group inScandinavia, has a turnover of approximately $ 30.000.000, and employs over 200 people.

For further information contact Datatronic AB,Box 42094, S-12612 Stockholm, Sweden.Phone 8-7445920or your nearest Commodore dealer.

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Box 42094 S-12612 STOCKHOLM SwedenPhone: 8-7445920 Telex: PET S 17828

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MMSFORTH VERSION 2.0:MORE FOR YOUR RADIO SHACKTRS-80 MODEL I OR MODEL III !

• MORE SPEED

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Ven/ compact compiled code plus VIRTUALMEMORY makes your RAM act larger. Variablenumber ol block buffers. 31-char.-unlque word-names use only 4 bytes In header!

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Add YOUR commands to lis 79-STANDARD-plii3

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Excellent full-screen Editor, structured &

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MMSFORTH UTILITIES DISKETTE: includes FLOATINGPOINT MATH (L.2 BASIC ROM routines plus Complexnumbers, Rectangular-Polar coordinate conversions,Degrees mode, more), plus a full Forth-styla Z80 ASSEM-BLER; plus a powerful CROSS-REFERENCER to listForth words by block and line. All on one diskette(requires MMSFORTH V2.0, 1 drive S 32K RAM) . S39.95*

FORTHCOM: communications package provides RS-232driver, dumb terminal mode, transfer of FORTH blocks,and host mode to operate a remote TRS-80 (requiresMMSFORTH V2.0, 1 drlvB & 32K RAM) 139.95*

THE DATAHANDLER V1.2: a very sophisticated data-base management system operable by non-pro-grammers {requires MMSFORTH V2.0, 1 drive & 32KRAM) $59.95'

MMSFORTH GAMES DISKETTE: real-time graphics &board games w'source code. Includes BREAKFORTH,CRASHFORTH. CRYPTOQUOTE, FREEWAY. OTHELLO& TICTACFORTH (requires MMSFORTH V2.0. 1 drive &32K RAM) $39.95*

Other MMSFORTH products under development

FORTH BOOKS AVAILABLE

MMSFORTH USERS MANUAL - w/o Appendices, for non-owners $15.00*

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PROGRAM DESIGN & CONSTRUCTION - Intro, to struc-tured program, good for Forth $8.95*

FORTH -79 STANDARD MANUAL ■ official reference to

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CALTECH FORTH MANUAL - good on Forth Internal

structure, etc $10.00*

FORTH SPECIAL ISSUE. BYTE Magazine (Aug. 1980) -westock this collector's Item for Forth users and beginners $4.00*

' - ORDERING INFORMATION: Software prices Includemanuals and require signing of a single system, single-user license. SPECIFY for Model I or Model III! Add$2.00 S/H plus $3.00 per MMSFORTH and $1.00 per addi-tional book; Mass. orders add 5% tax. Foreign ordersadd 20%. UPS COD, VISA & M/C accepted; no unpaidpurchase orders, please.

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maps to the top left corner of thescreen, the second byte maps oneposition to the right, then the third,the fourth, and so on to the last bytethat is mapped to the lower right cor-ner of the screen.

The quality of the image that getsto the screen depends on two factors:how sophisticated the video hard-ware is, and how much screenmemory is used. The simplest ar-rangement is used by the Radio ShackTRS-80 and the Commodore PET.These machines allocate a specific1 K bytes of RAM as screen memory.The video-hardware circuits simplypull data out of this area, interpretthem as characters (using a characterset in ROM), and put the resultingcharacters on the screen. Each byterepresents one character, allowing achoice of 256 different characters inthe character set. With 1 K bytes ofscreen RAM, 1024 characters can bedisplayed on the screen. There isn'tmuch that can be done to modify thisarrangement.

The Apple II, from Apple Com-puter Inc, uses more advanced videohardware. Three graphics modes areprovided: text, low-resolution (lo-res)graphics, and high-resolution (hi-res)graphics. The text graphics modeoperates much as the PET andTRS-80 displays operate. In the low-resolution graphics mode, the videohardware reaches into screen memoryand interprets it differently. Insteadof interpreting each byte as acharacter, each byte is interpreted astwo blocks of color. The value ofeach block (4 bits) specifies the colorof a single pixel. In the high-resolution graphics mode, each bit inscreen memory is mapped to a singlepixel. If the bit is on, the pixel getscolor in it; if the bit is off, the pixelstays dark. The situation is com-plicated by a variety of designnuances in the Apple, but that is thebasic idea.

The important point is that the Ap-ple has three display modes—threecompletely different ways of inter-preting the data in screen memory.The Apple video hardware is in-telligent enough to interpret a screen-memory byte as either an 8-bit

character (text mode), two 4-bit colornybbles (low-resolution mode), or 7individual bits for a bit map (high-resolution mode).

Atari 400/800 Display List

The Atari 400/800 display-listsystem represents a generalization ofthese systems. Where the PET andTRS-80 have one mode and the Applehas three modes, the Atari 400/800has fourteen modes. A second impor-tant difference is that Atari 400/800display modes can be mixed on thescreen. You are not restricted to achoice between a screen full of text ora screen full of graphics. Any collec-tion of the fourteen Atari graphicsmodes can be displayed on the screensimultaneously. The third importantdifference is that the Atari 400/800screen RAM can be located anywherein the address space of the computerand moved around while the programis running, whereas the othermachines use fixed-screen memoryareas.

This generality is made possible bya video microprocessor called AN-TIC. Where earlier systems usedrather simple video circuitry, Ataridesigned a full-scale microprocessorjust to handle the intricacies of thetelevision display. ANTIC is a truemicroprocessor—it has an instructionset, a program, and data. The pro-gram for ANTIC is called the displaylist. The display list specifies threethings: where the screen data can befound, what display modes to use tointerpret the screen data, and whatspecial display options (if any) shouldbe implemented.

When using the display list, it is im-portant to shed the old view of ascreen as a homogeneous image in asingle mode and see it instead as astack of mode lines. A mode line is acollection of horizontal scan lines. Itstretches horizontally all the wayacross the screen. An Atari graphics 2mode line is 16 horizontal scan lineshigh, while a graphics 7 mode line isonly 2 scan lines high. Many graphicsmodes available from BASIC arehomogeneous; an entire screen of asingle mode is set up. But you mustnot limit your imagination to this pat-

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You get plentyof practical experience.Using the NRI DiscoveryLab® that also comes as partof your course, you b.uild and study circuits rangingfrom the simplest to the most advanced. You analyzeand troubleshoot using the professional BeckmanLCD digital multimeter you keep to use later in yourwork. Then you use the lab and meter to actuallyaccess the interior of your computer... build specialcircuits and writeprograms to control them. You"see" your computer at work and demonstrate itspower.

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BYTE September 1981 289

Value of Bit PairBinary Decimal

00

0110

11

Atari ColorRegister Used

COLBAKCOLPF0COLPF1COLPF2

Table 1: Atari color-register assign-ment in four-color map mode.

tern; with the display list, you cancreate any sequence of mode linesdown the screen. The display list is a

collection of code bytes that specifythat sequence.

ANTIC's Instruction Set

ANTIC's instruction set is rathersimple. There are four classes of in-structions: map-mode instructions,character-mode instructions, blank-line instructions, and jump instruc-tions. Map-mode instructions causeANTIC to display a mode line withsimple colored pixels (no characters).Character-mode instructions causeANTIC to display a mode line withcharacters in it. Blank-line instruc-

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tions cause ANTIC to display anumber of horizontal scan lines witha solid background color. Jump in-structions are analogous to a 6502IMP instruction; they reloadANTIC's program counter with anew value. There are also four specialoptions that can sometimes bespecified by setting a designated bit inthe ANTIC instruction. These op-tions are: display-list interrupt (DLI),load-memory scan (LMS), verticalscroll, and horizontal scroll.

Map-mode instructions cause AN-TIC to display a mode line containingpixels with solid color in them. Thecolor that is displayed comes from acolor register. The choice of colorregister is specified by the value of thescreen data. In four-color map modes(BASIC modes 3, 5, and 7, and AN-TIC modes hexadecimal 8, A, D, andE), a pair of bits is required to specifya color register; these values are givenin table 1. [Unfortunately, thegraphics mode numbers in BASIC donot correspond to the mode numbersused by ANTIC; this often causesconfusion... ,GW]

Since only 2 bits are needed tospecify one pixel, four pixels are en-coded in each screen-data byte. Forexample, a byte of screen data con-taining the hexadecimal value IBwould display four pixels; the firstwould be the background, the secondwould be color register 0, the thirdwould be color register 1, and thefourth would be color register 2:

hexadecimal IB= binary 00011011= 00 01 10 11

In two-color map modes (BASICmodes 4, 6, and 8, and ANTIC modeshexadecimal 9, B, C, and F), each bitspecifies one of two color registers. Abit value of 0 selects background col-or for the pixel; a bit value of 1 selectscolor register 0 for the pixel. Eightpixels can be stored in one screen-data byte.

There are eight different map-display modes. They differ in thenumber of colors they display (twocolors versus four colors), the verticalsize one mode line occupies (1, 2, 4,

290 September 1981 © BYTE Publications Inc

Circle 259 on inquiry card.

Circle 68 on inquiry card.

CompuServe isa lot more thanfan and gamesand news.

Although we're probably bestknown for our consumer-orientedservices, CompuServe maintainspowerful services for the seriouscomputer user. CompuServe hashelped some of the nation's largestcompanies and financial institu-tions through a wide range ofbusiness and scientific-orientedcomputer programs. With ourInformation Service, we can extendthis expertise to you. Here aresome of the programs availableto the personal computer userthrough the CompuServeInformation Service:

PASCAL: DEC User Group

version of this famous language.

XF4: Extended CompuServe

Fortran compiler.

MACRO: Advanced Macro

Assembly language for PDP-10.

Talk about fast.

FILGE: Fast, easy file generator

and editor. Line oriented, no line

numbers required!

XBASIC: CompuServe extended

BASIC.

JUMBLE: File encryption program.

TECO: High level text editor.

LINK: Linking loader program.DDT: Dynamic debugging tool.CREF: Symbolic cross-referencegenerator used with languagecompilers.

FILCOM: File comparisonprogram.

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RUNFIO: Word processing andtext formatting program (writeresumes etc.).CONCOR: Concordancegenerator. This program is veryuseful for documentation purposes.CONCOR reads an ASCII file andcreates an output file which con-tains a line numbered listing ofthe original file, and a list of all thewords contained in the file alongwith the numbers of the lines onwhich each word occurs (similarto an index).

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ANTIC

BASIC

Number of Scan Lines Per

Pixels

Per

Bytes Per

Bytes Per

Mode

Mode

Colors

Mode Line

ModeL

me

Line

Screen

2

0

2

8

40

40

960

3

none

2

10

40

40

760

4

none

4

8

40

40

960

5

none

4

16

40

40

480

6

1

5

8

20

20

480

7

2

5

16

20

20

240

8

3

4

8

40

10

240

9

4

2

4

80

10

480

A

5

4

4

80

20

960

B

6

2

2

160

20

1920

C

none

2

1

160

20

3840

D

7

4

2

160

40

3840

E

none

4

1

160

40

7680

F

8

2

1

320

40

7680

Table 2:

Atari graphics modes and their characteristics.

Note that the same graphics

mode is

given a

different

number by BASIC and by ANTIC. The ANTIC mode

number

refers to

one mode line o/ a groen foW

of graphics,

while the BASIC mode

number

refers to

a certain

arrangement of mode lines (most

or all of u,

hich are the

given kind of graphics) that defines an entire screen of

video display.

or 8 scan lines), and the number ofpixels that fit horizontally into onemode line (40, 80,160, or 320). Thus,some map modes give better resolu-tion; these will require more screenmemory. Table 2 presents this infor-mation for all modes.

Character-mode instructions causeANTIC to display a mode line withcharacters in it. Each byte in screenRAM specifies one character. Thereare six character-display modes.Character displays will be discussedin a future BYTE article in this series.

Blank-line instructions produce"blank" lines consisting of only a

solid background color. There areeight blank-line instructions; theyspecify skipping one through eightblank lines.

There are two jump instructions.The first (JMP) is a direct jump; itreloads ANTIC's program counterwith a new address that follows theJMP instruction as an operand. Itsonly function is to provide a solutionto a tricky problem. ANTIC's pro-gram counter is only 10 bits wide.Thus, it cannot cross a 1 K-byteboundary. If the display list mustcross a 1 K-byte boundary, it mustuse a JMP instruction to hop over the

boundary. This means that displaylists are not fully relocatable.

The second jump instruction (JVB)is more commonly used. It reloadsthe program counter with the value inthe operand and waits for the televi-sion to perform a vertical blank. Thisinstruction is normally used to end adisplay list by jumping to the top ofthe display list. Jumping to the topturns it into an infinite loop; ANTICwaits for vertical blank to insure thatthe infinite loop is synchronized tothe display cycle of the television.Both JMP and JVB are 3-byte instruc-tions; the first byte is the operationcode (JMP or JVB), the second andthird bytes are the address to jump to(low byte, then high byte).

The four special options mentionedpreviously will be discussed in futurearticles in this series. However, theload-memory scan option must havea preliminary explanation. This op-tion is selected by setting bit 6 of amap-mode or a character-mode in-struction byte. When ANTIC en-counters such an instruction, it willload its memory-scan counter withthe two following bytes. Thismemory-scan counter tells ANTICwhere the screen memory is, and AN-TIC begins fetching display data fromthis area. The LMS instruction is a3-byte instruction: a 1-byte operationcode followed by 2 bytes of operand.In simple display lists, the LMS in-

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292 September 1981 © BYTE Publications Inc

Circle 382 on inquiry card.

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struction is used only once, at thebeginning of the display list. It maysometimes be necessary to use a sec-ond LMS instruction. The need ariseswhen the screen-memory area crossesa 4 K-byte boundary. (The memory-scan counter is only 12 bits wide,which is why it cannot cross a 4 Kboundary.) In this case, an LMS in-struction must be used to jump thememory-scan counter over theboundary. This means that displaydata are not fully relocatable. LMSinstructions have wider uses that willbe discussed later in this series.

Building Display Lists

Every display list should begin withthree "blank-eight-lines" instructions.This defeats vertical overscan bybringing the beginning of the usefuldisplay 24 scan lines down. After thisis done, the first display line shouldbe specified. Simultaneously, theLMS should be used to tell ANTICwhere it will find the screen memory.Then follows the actual display list,which lists the display bytes for the

mode lines on the screen. The totalnumber of horizontal scan lines pro-duced by the display list shouldalways be 192 or less; ANTIC doesnot maintain the screen-timing re-quirements of the television. If yougive ANTIC too many scan lines todisplay, it will do so, but the televi-sion screen will probably roll.Displaying fewer than 192 scan linescauses no problems; indeed, itdecreases 6502 execution time byreducing the number of cycles stolenby ANTIC. The programmer mustcalculate the sum of the horizontalscan lines produced by his or herdisplay list and verify it. The displaylist must end with a JVB instruction.

A typical display list for a standardBASIC graphics mode 0 display (allvalues are in hexadecimal) is given intable 3. As you can see, this displaylist is short—only 32 bytes. Mostdisplay lists are less than 100 byteslong. Furthermore, they are quitesimple in structure and easy to set up.

To implement your own displaylist, you must first design the display

Hexadecimal Hexadecimal

Address Value

Meaning

7BE0 70

blank 8 lines

70

blank 8 lines

70

blank 8 lines

42

display ANTIC mode 2 (BASIC mode 0)

20

also, screen memory starts at 7C20

7C

02

display one mode line of ANTIC mode 2

02

02

02

02

02

02

02

02

02

02

02

02

02

02

02

02

02

02

02

02

02

02

41

JVB instruction—wait for the vertical-

E0

blank signal, then jump to the beginning

7B

of the display list, which starts at $7BE0

Table 3: The display list for i

i standard BASIC graphics mode 0 display.

294 September 1981 © BYTE Publications Inc

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BYTE September 1981 295

format. This is best done on paper.Lay out the screen image andtranslate it into a sequence of modelines. Keep track of the scan-linecount of your display by looking upthe scan-line requirements of thevarious modes in table 2. Translatethe sequence of mode lines into a se-quence of ANTIC mode bytes. Put 3"blank-eight-lines" bytes (hexa-decimal 70) at the top of the list. Setbit 6 of the first display byte (that is,make the upper nybble a 4)—thismakes it a load-memory scan com-mand. Follow with 2 bytes thatspecify the address of the screen RAM(low byte, then high). Then followthis with the rest of the display bytes.At the end of your display list, put inthe JVB instruction (hexadecimal 41)and the address of the top of thedisplay list. Store all these bytes intomemory. They can be anywhere youwant; just make sure they don'toverlie something else, and be sureyour JVB instruction at the end of thedisplay list points to the top of thedisplay list.

The display list must not cross a1 K-byte address boundary. If youabsolutely must have it cross such aboundary, insert/ a JMP instructionjust in front of the boundary, with theJMP instruction's operand being theaddress of the first byte on the otherside of the boundary. Next, you mustturn off ANTIC for a fraction of asecond while you rewrite its display-list pointer. Do this by writing a 0 in-to hexadecimal location 22F (knownas SDMCTL). Then store the addressof the new display list into hexa-decimal locations 230 and 231 (lowbyte, then high). Lastly, turn ANTICback on by depositing a hexadecimal22 into SDMCTL. During the verticalblank, while ANTIC is quiet, theoperating system will reload ANTIC'sprogram counter with these newvalues.

Screen-Data Placement

Screen memory can be placedanywhere in the address space of thecomputer. Normally, the display listspecifies the beginning of the screenmemory with the first display instruc-tion—the initial LMS instruction.

However, ANTIC can execute a newLMS instruction with each displayline of the display list, if this isdesired. In this way, informationfrom all over the address space of thecomputer can be displayed on a singlescreen. This can be of value in settingup independent text windows.

There are several restrictions inyour placement of the screenmemory. First, screen memoryshould not cross a 4 K-byte addressboundary. If you cannot avoid cross-ing a 4 K-byte boundary (as wouldbe the case in BASIC mode 8, whichuses 8 K bytes of RAM), you mustreload the memory-scan counter witha new LMS instruction. Second, ifyou wish to use any of the Atari

Screen memory can

be placed anywhere

In the address space

of the computer.

operating-system screen routines,you must abide by the conventionsthe operating system uses. This canbe particularly difficult when using amodified display list in a BASIC pro-gram. If you alter a standard displaylist from a BASIC program and thenattempt to PRINT or PLOT to thescreen, the operating system will doso under the assumption that thedisplay list is unchanged. This willprobably result in a garbled display.

There are three ways the displaycan fail when you attempt this. First,BASIC may refuse to carry out ascreen operation because it is impossi-ble to do with the graphics mode thatthe operating system thinks it is in.The operating system stores the valueof the graphics mode that it thinks ison the screen in hexadecimal address57. You can fool the operating systeminto cooperating by POKEing a dif-ferent BASIC mode value there.POKE the BASIC mode number, notthe ANTIC mode number.

The second failure arises when youmix mode lines with different screen-memory byte requirements. Somemode lines require 40 bytes per line,some require 20 bytes per line, andsome require only 10 bytes per line.

Let's say that you insert one 20-bytemode line into a display list with40-byte mode lines. Then you PRINTtext to the display. Everything abovethe interloper line is fine, but below itthe characters are shifted twentyspaces to the right. This is because theoperating system assumed that eachline would require 40 bytes and posi-tioned the characters accordingly.But ANTIC, when it encountered theinterloper line, took only 20 bytes ofwhat the operating system thoughtshould be a 40-byte line. ANTIC in-terpreted the other 20 bytes asbelonging to the next line anddisplayed them there. This resulted inthe next line and all later lines beingshifted twenty spaces to the right.

The only absolute way around thisproblem is to refrain from usingBASIC PRINT and PLOT statementsto output to a mixed display-listscreen. The quick and dirty solutionis to organize the screen into linegroups that contain integer multiplesof the standard byte requirement.That is, do not insert a 20-byte modeline into a 40-byte display; instead,insert two 20-byte lines or one20-byte line and two 10-byte lines. Aslong as you retain the proper integermultiples, the horizontal shift will beavoided.

This solution accentuates the thirdproblem with mixed display lists andBASIC: vertical shifts. The operatingsystem positions screen material ver-tically by calculating the number ofbytes to skip down from the top ofthe screen. In a standard 40-byte linedisplay, BASIC would position thecharacters onto the tenth line by skip-ping 360 bytes (40 bytes per line times9 full lines) from the beginning. If youhave inserted four 10-byte lines,BASIC ends up 3 lines further downthe screen than you would otherwiseexpect. Furthermore, different modelines consume different numbers ofscan lines, so the position on thescreen will not be quite what you ex-pected if you do not take scan-linecosts into account.

As you can see, mixed-modedisplays can be difficult to use in con-junction with the operating system.Often, you must fool the operatingsystem to make such displays work.

296 September 1981 © BYTE Publications Inc

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To PRINT or PLOT to a mode win-dow, POKE the BASIC mode numberof that window to hexadecimal loca-tion 57, then POKE the address of thetop left pixel of the mode windowinto hexadecimal locations 58 and 59(low byte, then high). In charactermodes, execute a POSITION 0,0 tohome the cursor to the top left cornerof the mode window. In map modes,all PLOTs and DRAWTOs will bemade using the top left corner of themode window as the origin of thecoordinate system.

The display-list system can be usedto produce appealing screen displays.Its most obvious use is for mixing textand graphics. For example, you couldprepare a screen with a bold BASICmode 2 title, a medium-size BASICmode 1 subtitle, and small BASICmode 0 fine print. You could thenhave a BASIC mode 8 picture in themiddle, with more text at the bottom.

With assembly-language routines,modified display lists are best used byorganizing the screen into a series ofwindows, each window having itsown LMS instruction and its own in-dependent RAM area.

Modification Applications

One simple application of display-list modifications is to verticallyspace lines on the screen by insertingblank-line bytes. This will add somevertical spacing, which will highlightcritical messages and enhance thereadability of some displays.

Another important use of display-list modifications is in providing ac-cess to features not available fromBASIC. There are three text modessupported by ANTIC that BASICdoes not support. You can gain accessto these modes only by modifying thedisplay list. There are also display-list-interrupt and fine-scrollingcapabilities that are only availableafter the display list is modified.These features are the subjects of laterarticles in this series.

Manipulations with the LMS in-struction and its operand offer manypossibilities to the creative program-mer. For example, by changing theLMS during vertical blank, the pro-grammer can alternate screen images.

298 September 1981 © BYTE Publications Inc

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GRAFTRAX 80 more than doubles the features avail-able in an Epson MX-80 or MX-80 F/T. For instance,we've added nice little touches like an italic characterset — which doubles the number of font types to 24.And with GRAFTRAX 80, you can change style, sizeand density anywhere in the line. And backspace thehead. And use block graphics with any computer. Andredefine all escape codes under software control.

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Circle 141 on Inquiry card.

BYTE September 1981 299

Pi

first frame 1second frame Bthird frame Bfourth frame Beffective luminance x 4 2perceived luminance

Table 4: Advanced color and Ithe video display; see the text

xel C11BB4

ontents (By Color

112 31 1 B B1 1 B BB 1 B B6 8 10 12

Register)2 3 22 3 2B B 2B B B20 24 30

3 2 33 2 33 2 3B 2 336 40 48

iminance control through the high-speed changing offor details.

This can be done at slow speed tochange between predrawn displayswithout having to redraw each one.Each display would continue to residein (and consume) memory even whileit is not in use, but it would beavailable almost instantly. Thistechnique can also be used for anima-tion. By flipping through a sequenceof displays, cyclic animation can beachieved. The program to do thiswould manipulate only 2 addressbytes to display thousands of bytes ofmemory.

It is also possible to superimposeimages by flipping screens at highspeed. The human eye has a timeresolution of about y16 of a second,

so a program can cycle between fourimages, one every V60 of a second,so each repeats every yH of a sec-ond. In this way, up to four imagescan appear to reside simultaneouslyon the screen. There are somedrawbacks to this method. First, fourseparate displays may well cost a lotof memory. Second, each display im-age will be washed out because it onlyshows up one quarter of the time.This means that the background of alldisplays must be black, and each im-age must be bright. Furthermore,there will be some unpleasant screenflicker when this technique is used. Aconservative programmer might con-sider cycling between only three or

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even two images. This technique canalso be used to extend the color andluminance resolution of the com-puter. By cycling between four ver-sions of the same image, each versionstressing one color or luminancerange, a wider range of colors andluminosities is available.

For example, suppose we wish todisplay a bar of many differentluminances. We first set our four col-or registers to the following hexa-decimal values:

background: 00

playfield 1: 02

playfield 2: 0A

playfield 3: 0C

If we put the images described in table4 into each of the screen-memoryareas, we can achieve much finerluminance resolution.

A final suggestion concerns a sub-ject that is laden with opportunities,but that is as little understood asthe dynamic display list. This is adisplay list that the 6502 changes dur-ing vertical-blank periods. It shouldbe possible to produce interesting ef-fects with dynamic display lists. Forexample, a text-editing programcould dynamically insert blank linesabove and below the screen line beingedited to set it apart from the otherlines of text. As the cursor is movedvertically, the display list is changedto isolate the screen line the cursor ison. The technique is odd but very ef-fective.

Conclusions

The display list is a powerfulsystem for creating and controllingdisplays. It is not a simple system. Inessence, it is a scheme for mating twocompletely different technologies, thetelevision and the microcomputer.When I consider the differences be-tween these two technologies and theexacting demands of each, I am sur-prised that the display-list systemachieves such a favorable combina-tion of power and simplicity. Evenmore surprising is the way thedisplay-list system supports an evenmore powerful set of graphicscapabilities, such as graphics indirec-tion, display-list interrupts, and finescrolling. These will be the subjects offuture articles in this series. ■

300 September 1981 © BYTE Publications Inc

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Natural-Language Processing

The Field in Perspective

Gary G Hendrix

Natural Language Program

Aritificial Intelligence Center

SRI International

333 Ravenswood Ave

Menlo Park CA 94025

Earl D Sacerdoti

Machine Intelligence Corp

1120 San Antonio Rd

Palo Alto CA 94303

Through a process spanning thousands of years,natural languages have evolved to meet the manifoldneeds of people to communicate and record a diversity ofinformation in a wide variety of circumstances. Naturallanguage is the medium of the butcher, the baker, and thecandlestick maker; the poet and the lover; the politicianand the preacher; the parent and the child. Even for thescientist and computer programmer, it is the mothertongue—the language resorted to when formal expres-sions and intuition fail.

Natural languages stand in marked contrast to formallanguages, such as BASIC and Pascal, which were de-signed to be easily understood by computers and areintended for the specialized task of expressing algorithmsand data structures. The fluent use of natural language isan information-processing activity of great complexity.Endowing computers with this ability has long been amajor goal of research in artificial intelligence (also calledmachine intelligence), a branch of experimental computerscience that studies the nature of knowledge and itsmanipulation.

Understanding the computational mechanisms thatunderlie the use of natural language is the central objec-tive of computational linguistics (see the text box at theend of the article), a science at the juncture of artificial in-telligence, philosophy, linguistics, and psychology. Thetwo primary goals of this field are:

• to understand how humans communicate

• to create machines with human-like communicationskills

The first is a scientific goal pursued to help us understandourselves. In particular, although we all are implicitly ex-pert in the use of natural language, we have only vaguenotions of the mental processes involved. A clearer in-

sight into their essential nature and functioning mightenable us to be better communicators, to train ourchildren better in language skills, and even to designmore efficient intercomputer communications.

The second goal is an engineering one pursued for apractical purpose—to create machines that can com-municate with people in languages they already know. Atpresent, only a small segment of the population, com-puter programmers, can communicate with computers.The advent of machines that understand natural lan-guages will make it possible for virtually anyone to makedirect use of powerful computational systems.

Progress in computational linguistics is facilitated bypursuing both of the above goals simultaneously. Crea-tion of mechanical schemes for dealing with some aspectof natural-language processing sheds light on how itmight actually be performed by the human brain.Similarly, evidence derived from observing how peopleuse language suggests prospective computationalmechanisms or, more often, provides valuable insightsinto the reasons particular mechanical processes fail.

To create computer systems that deal with certainsignificant subsets of natural-language phenomena, it isprobably not necessary to perform the task in a wayclosely simulating computational processes in the humanbrain. This should not be surprising. Mechanical dish-washers use a nonhuman technique to produce a resultequivalent to that of a human dishwasher. For inter-actions about very limited subject areas, we can hope toemploy thoroughly nonhuman techniques in dealing withnatural language. Nevertheless, machines concerned withany but the most mundane aspects of human languagewill probably have to deal with human psychology. Afterall, natural language has evolved as an efficient tool forconveying information between human minds. One of

304 September 1981 © BYTE Publications Inc

The most comprehensive and usefulcomputer reference in the world.

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the participants in a man-machine dialogue operates withall the constraints and richnesses of the human psyche;the other has to take these into account.

The ultimate goal of creating machines that can in-teract in a facile manner with people remains far off,awaiting both improved information-processing algo-rithms and alternative computing architectures. How-ever, progress in the last decade has demonstrated thefeasibility of employing today's computers to deal withnatural-language input in highly restricted contexts.Futhermore, microcomputer implementation of theselimited language-processing techniques is leading to morepractical, cost-effective systems.

In this article, we offer an overview of the potential ap-plications, experimental systems, existing techniques,research problems, and future prospects in this rapidlyevolving field. We will address major issues in natural-language processing by focusing on several representativesystems, necessarily leaving much important workunmentioned. For example, we will not discuss the com-plex issues involved in understanding spoken (as opposedto typed) language. Our intentions are to demonstratethat natural-language processing techniques are usefulnow, to reveal the richness of the computations per-formed by human natural-language communicators, andto explain why the fluent use of natural language by ma-chines remains an elusive aspiration.

Applications of Natural-Language Processing

To motivate our discussion about how to approach thetechnological goal of creating a machine with human-likecommunication skills, let us consider some potentialareas for the application of natural-language processing:

• Machine translation—The oldest dream of computa-tional linguistics is of a mechanical device that can readdocuments written in one natural language and producecorresponding documents written in other languages, butwith equivalent meanings. In fact, the birth of computa-tional linguistics occurred in 1946, when Warren Weaverand A Donald Booth first suggested the use of a digitalcomputer to create such a device. The Association forComputational Linguistics, the professional organizationin this discipline, was originally named the Associationfor Machine Translation and Computational Linguistics.

• Document understanding—Beyond simply translatinga document from one language to another, a device mightread and understand documents, fitting their informationinto a larger framework of knowledge. A practical deviceof this sort would read and assimilate a document muchas a person would. The device might subsequently pro-duce abstractions of the document, alert people likely tobe interested in it, or answer specific questions based onits information. If such a device had read many docu-ments, it might be able to act as a librarian, directingusers to pertinent references.

• Document generation—A task related to documentunderstanding is document generation. We can envisagea device that translates information stored in a formal

306 September 1961 © BYTE Publications Inc

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MACHINE

Figure 1: The typical nontechnical user confronts a "black box"that contains large amounts of knowledge on a given subject.

language in a computer's memory into ordinary lan-guage. For example, the designer of an automobile enginemight describe repair procedures in a formal language.(After all, we expect that the designing of mechanical de-vices will someday be done principally by computer sys-tems, which may prefer formal languages.) From this for-mal description, instruction manuals in various lan-guages could be generated.

A more sophisticated system could generate specialmanuals for particular groups or individuals. Taking into

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account that mechanics know much about auto repair, asmart system would generate a different manual formechanics than for automobile owners, but on the basisof the same underlying information. Information onelementary mechanical tasks would be included inmanuals for less knowledgeable individuals. An ultimatesystem would tailor a manual to the background of eachindividual.

It is worth noting that a repair manual need not bewritten in linear sequence in a typical book format. Usinga computer, advice about how to proceed on any par-ticular problem could be dynamically generated to applyspecifically to the task at hand. We will return to thistopic later in the article.

• As part of a system—An interesting use of natural-lan-guage processing is as part of a larger computer-basedsystem. For example, imagine devices that not only com-municate in English, but also:

• provide answers to questions by accessing large databases

• control complex equipment such as industrial robots,power generators, or missile systems

• furnish expert advice about medical problems,mechanical repairs, how to buy stocks, or what tocook for supper

• teach courses in a broad range of subjects

An extreme example of a computer-based system thatwould use natural-language processing as an integralcomponent is a robot that communicates in English. Sucha robot might be expected to perform as many tasks in-volving the use of natural language as might be done by ahuman assistant.

The importance of these potential applications and thebasic science needed to make them possible has long beenappreciated by scientific-funding agencies of the UnitedStates government. Current progress in the field is duelargely to support from the Defense Advanced ResearchProjects Agency, the National Science Foundation, andthe Office of Naval Research.

What Existing Systems Can Do

One of the most important and feasible areas for theapplication of natural-language processing is accessingdata in data bases. Billions of dollars have been spent incollecting and encoding such data. However, this infor-mation is generally not readily available to the peoplewho need it. The situation is illustrated by figure 1.

An executive in the widget business wants to direct asimple question to his black box. He wants to know,"How many widgets did we sell in August?" He knowsthe information is in the black box, but he lacks the ex-pertise to make the box understand him.

As shown in figure 2, he must find an interpreter (com-puter programmer) who can translate his question into aformal query to give to the machine. Unfortunately, pro-grammers are out drinking coffee when you need them,

308 September 1981 © BYTE Publications lnc

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BYTE September 1981 309

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INTERPRETER

Figure 2: The nontechnical user obtains information from thecomputer through the use of an interpreter (computer program-mer), who translates the English question into a form themachine understands.

or they are working on a project more important thanyour project—so they cannot help you this week. When aprogrammer is available, misunderstandings often occurand there are problems in creating proper code. By thetime an answer is extracted from the computer, it may nolonger be timely and may not even be relevant!

The LADDER System

To produce timely answers to questions and quicklyclear up problems as to how a decision-maker's questionis to be interpreted, the turnaround time must be cut fromhours or days to seconds.

Research groups around the world are attempting to dothis by automating the programmer in figure 2. For exam-ple, the LADDER system developed at SRI International(see references 11 and 12 at the end of this article) iscapable of translating a question such as:

TO WHAT COUNTRY DOESTHE FASTEST SUB BELONG?

into either the code of listing 1 or listing 2, depending onwhich DBMS (data-base management system) has therelevant data. An explanation of these segments of codeis unnecessary here. The point is that systems exist thatare capable of accepting simple English queries specifying

Text continued on page 314

310 September 1981 © BYTE Publications Inc

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Circle 169 on inquiry card.

BYTE September 1981 311

Listing Is An English-language query translated to an equivalentprogram in DATALANGUAGE.

Listing 2: An English-language query translated to an equivalentDBMS20 program.

English Query—

To what country does the fastest sub belong?DATALANGUAGE Query—BEGIN

DECLARE Yl STRING (,100) ,D = '}'DECLARE Y2 STRING (,100) ,D = T Y2 = '00.0'DECLARE Y3 INTEGER Y3 = 0DECLARE Y5 STRING (,100) ,D = '}' Y5 = 0DECLARE Y4 STRING (,100) ,D = '}' Y4 = 0FOR Rl IN SHIPCLASCHAR WITH (R1.TYPE2 EQ lS') AND

(Rl.TYPElEQ'S')FOR R2 IN SHIPCLASDIR WITH (R2.SHIPCLAS EQRl.SHIPCLAS)FOR R3 IN SHIP WITH (R3.UICVCN EQ R2.UICVCN)BEGIN

Yl = R3.MCSF

IF Yl LE '99.9' AND Y2 LT Yl THENBEGIN

Y2 = Yl

Y5 = R3.NAT

Y4 = R3.NAM

Y3 = 1

END

END

IF Y3 EQ 1 THEN

BEGIN

NSTDPORT. STRING 1

= Y4

NSTDPORT.STRING2

= Y5

END

END

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English Query—

To what country does the fastest sub belong?DBMS20 Query—

COMPUTE XSTRX11 = '00.0'$

COMPUTE XY10 = 0 $

FIND FIRST SHIPCLASCHAR RECORD OF BLUEAREA

AREAS13 IF ERROR-STATUS = 307 GO TO 14 $

COMPUTE XAND16 = 0 $

IF SHIPCLASCHAR-TYPE2 NE 'S' GO TO 17 $

COMPUTE XAND16 = 1 $17 IFXAND16 = 0GOTO 15$

COMPUTE XAND 18 = 0 $

IF SHIPCLASCHAR-TYPE1 NE 'S' GO TO 19 $

COMPUTE XAND 18 = 1 $19 IF XAND18 = 0 GO TO 15 $

COMPUTE XSTRZ12 = SHIPCLASCHAR-MCS $

IF XSTRZ12 LT '00.0' OR XSTRX11 LE XSTRZ12 GO TO 15 $

COMPUTE XSTRX 11 = XSTRZ12 $

COMPUTE XY10 = 1 $

COMPUTE XSTR29 = SHIPCLASCHAR-MCS $15 FIND NEXT SHIPCLASCHAR RECORD OF BLUEAREA

AREAS

GO TO 13 $

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20

24

26

28

30

34

35

37

3632

3122

21

IF XY10 = 0 GO TO XT $

FIND FIRST SHIPCLASCHAR RECORD OF BLUEAREA

AREA $

IF ERROR-STATUS = 307 GO TO 21 $

COMPUTE XAND23 = 0 $

IF SHIPCLASCHAR-TYPE2 NE 'S' GO TO 24 $

COMPUTE XAND23 = 1 $

IF XAND23 = 0 GO TO 22 $

COMPUTE XAND25 = 0 $

IF SHIPCLASCHAR-TYPE1 NE 'S' GO TO 26 $

COMPUTE XAND25 = 1 $

IF XAND25 = 0 GO TO 22 $

COMPUTE XAND27 = 0 $

IF SHIPCLASCHAR-MCS NE XSTR29 GO TO 28 $

COMPUTE XAND27 = 1 $

IF XAND27 = 0 GO TO 22 $

FIND FIRST SHIPCLASDIR RECORD OF BLUEAREA AREA

$

IF ERROR-STATUS = 307 GO TO 31 $

COMPUTE XAND33 = 0 $

IF SHIPCLASDIR-SHIPCLAS NE SHIPCLASCHAR-

SHIPCLAS GO TO 34 $

COMPUTE XAND33 = 1 $

IF XAND33 = 0 GO TO 32 $

SET SHIP-UICVCN TO SHIPCLASDIR-UICVCN $

FIND SHIP RECORD $

IF ERROR-STATUS = 326 GO TO 36 $

PRINT SHIP-NAM SHIP-NAT $

FIND DUPLICATE SHIP RECORD $

GO TO 35 $

* $

FIND NEXT SHIPCLASDIR RECORD OF BLUEAREA AREA $GO TO 30 $

* $

FIND NEXT SHIPCLASCHAR RECORD OF BLUEAREA

AREAS

GO TO 20 $

* $

GO TO XT $END

312 September 1981 © BYTE PublicaSons Inc

Circle 309 on inquiry card.

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Circle 307 on inquiry card.

Listing 3: An actual conversation with the LADDER system.Boldface words represent user input. Material in square bracketsreplaces lengthy material not relevant to this article.

1—Give me the length of the Kenedy.

spellings KENNEDYPARSED!Give the length of the ship KENNEDY IF

LEN - 1072

2—width and draft

PARSED!

Trying Ellipsis: GIVE ME WIDTH AND DRAFT OF THE KENEDY

Give the beam and draft of the ship KENNEDY IF

(BEAM 130 DFT 36)

3—Who is her commander?

Give the rank and name of the commander of the ship KENNEDY IF

CRANK CAPT NAME MOFFETT P)

4—What about the Fox?

PARSED!

Trying Ellipsis on: THE FOX

WHO IS THE FOX COMMANDERGive the rank and name of the commander of the ship FOX(RANK CAPT NAME EVERETT I)

5—What U.S. merchant ships carrying vanadium ore are within 500miles of the Kimlow?PARSED!

Give the position of and time at position for the ship KIMLOW TGive the name of merchant American ship S

where the type of cargo on S is VNAD

the great-circle distance from the position of S to15-33N, 30-10W, is less than or equal to 500SHIP = GREENVILLE VICTORY, CRAIN ME, TOTOR6—How fast are the U.S. subs with lengths greater than 150 feet?PARSED!Give the maximum cruising speed for and name of American ship S

where the first character of the type of S is Sthe second character of the type of S is Sthe length of S is greater than 150[A long table relating the names and maximum cruising speeds ofAmerican submarines is printed.]7—What French ships are at readiness status 1?PARSED!Give the name of French ship S

where the state of readiness of S is 1

There is no French ship SNONE

Text continued from page 310:

what information a user wants, then generating fairlycomplex programs specifying how the computer is toretrieve the information.

Two problems are being confronted together:

Problem 1: The system must translate from English into

a formal language.Problem 2: The system must convert a statement of

what is wanted into a statement of how to

get it.

Problem 2 is concerned with automatic programming, anartificial-intelligence problem currently receiving muchattention (see reference 2). (Fortunately, most work onnatural-language processing needs to consider only ahighly restricted subset of this general problem.)

What it's like to use a system such as LADDER is sug-gested by the transcript, shown in listing 3, of an actualinteraction. The system prompts users with a transactionnumber followed by a hyphen. The user then types in aquestion or command. (In this and future listings, werefer to the question half as a query and to the ques-tion/response pair as an interaction.) Query 1, "Give methe length of the Kenedy," contains a misspelled word.LADDER corrects this automatically, typing a note to theuser directly below the input line. Once LADDER hascorrected the spelling error and completed an analysis ofthe input, it types the message "PARSED!", and displaysits interpretation of the user's query. The system thencalls a remote data base to retrieve the answer—in thiscase, the length (abbreviated to LEN) of the Kennedy is1072 (feet).

Query 2 is not a complete sentence. In fact, it makes nosense when considered in isolation. But in the context ofthe preceding query, it is clear that the intended meaningis, "Give me the width and draft of the Kennedy." Leav-ing out pieces of a sentence is called ellipsis. Processingsuch elliptical inputs is more difficult than it may seem.The system has to avoid such interpretations as, "Giveme the length of the width and draft," or even, "Givewidth and draft the length of the Kennedy."

Query 3 illustrates the use of a pronoun, anotherlinguistic construct that cannot be interpreted in isola-tion.

Query 4 demonstrates a more sophisticated form ofellipsis in which the analysis involves more than justgrammatical substitution of the new input into the oldone. (This is accomplished in LADDER by looking for"WHAT ABOUT" at the beginning of an input, ind thenapplying the standard elliptical technique what

follows.)

Query 5 illustrates a major benefit of natural-languageprocessing: the user can interact with the system in termsof the job being done, letting the system be concernedwith what is required from the data base. Though this isonly one question from the user's perspective, it requirestwo questions of the data base. First, the location of theKimlow must be determined, and then the appropriateships within 500 miles of that location must be retrieved.The process of translating from the user's terms to thoseof the data base obstructs the user's decision-making job.It is therefore an appropriate process to automate.

Interaction 6 causes a large body of information to beretrieved from the data base. Althoug omitted from thelisting to save space, a table summarizing the answer isdisplayed to the user.

Interaction 7 shows an example of a cooperativeresponse to the user's question. The user asks a questionabout the readiness of French ships. However, the database contains no information about French ships. There-fore, the literal answer to the user's question, NONE, isinappropriate by itself, since it leads the user to believe allFrench ships are unready. To provide a more informativeresponse, LADDER presents additional informationshowing the rationale for producing the NONE response.

314 September 1981 © BYTE Publications Inc

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LADDER'S methods for dealing with natural-languageinputs are similar to those used by compilers and inter-preters for such languages as BASIC and Pascal. For ex-ample, a BASIC interpreter might deal with assignmentstatements by looking for the pattern:

LET < variable > = < expression > .

This pattern could match an instruction of the form:

LET X = 5 + Y

with "X" filling the role of the < variable > and "5 + Y"filling the role of the < expression > . Associated with thispattern, the interpreter would have a function for storingthe value of the expression into the memory locationnamed by X.

Similarly, LADDER uses patterns such as:

WHAT <BE> THE < SHIP-ATTRIBUTES > OF< SHIP-DESCRIPTION >

that can match sentences such as:

WHAT ARE THE LENGTHS AND DRAFTS OFUS CARRIERS?

Like an interpreter or compiler, LADDER associates afunction with each pattern. The function associated with

the example just cited would produce calls to the data-base management system to retrieve attributes of shipsand take as parameters the names of the attributes and adescription of the ships of interest. Most of LADDER'Sknowledge about language and the world is implicitly en-coded in its grammar and associated functions. Thegrammar contains much information about the particulardata base being queried and is by no means a standardgrammar of English. A grammar of this type is called apragmatic or semantic grammar (see references 4 and 11).

Summary of LADDER-Like Systems

In a later section, we will say more about what systemslike LADDER can do. For now, it is sufficient to note thefollowing:

• The computer capability shown in the transcript oflisting 3 is of considerable practical utility.

• LADDER deals with a relatively large and complex database that includes over 100 fields in fourteen files and hasrecords for 40,000 ships.

• LADDER has been performing at this level of capabilitysince 1976 (except for the cooperative responses such asthose in interaction 7, which are relatively new—seereference 14).

• There are several systems in laboratories around theworld that are capable of essentially the same level of per-formance as shown in listing 3. These include the systemsdescribed in references 10, 14, 24, 25, 26, and 31.

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316 September 1981 © BYTE Publications Inc

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Circle 330 on Inquiry card.

BYTE September 1981 317

Listing 4: A dialogue between an expert and an apprenticerepairman showing definitely determined noun phrases(underlined).

A:

E:

HOW DO J_ REMOVE THE FLYWHEEL ?

FIRST LOOSEN THE TWO SMALL ALLEN

HEAD

SETSCREWS HOLDING IT TO THE SHAFT THEN PULL

IT OFF.

THE TWO SETSCREWS ARE LOOSE BUT I'M HAVINGTROUBLE GETTING THE WHEEL OFF.USE THE WHEEL PULLER . DO YOU KNOW HOW?NOLOOSEN THE SCREW IN THE CENTER AND PLACE THE

JAWS AROUND THE HUB OF THE WHEEL; THENTIGHTEN THE SCREW.

THE LITTLE METAL SEMICIRCLE FELL OFF WHEN J_TOOK THE WHEEL OFF.

For restricted classes of applications, systems such asLADDER provide language-processing capabilities thatare very useful. Nevertheless, LADDER falls far short ofbeing an ideal system, both conceptually and linguistical-

ly.

LADDER'S concept of the world is based on theunderlying conventional data-base management systemto which it provides access. Data-base managementsystems can effectively store large numbers of individual,concrete facts, such as:

Isolated from all contexts, this question should be inter-preted as a request for the names of the commanding of-ficers of all US tankers in the data base. But if a user hasjust asked the question, "What is the status of convoyC86? " and has received information on a number ofships in the convoy, including two US tankers, the sam-ple question should elicit the captains' names for only thetwo tankers in the convoy. LADDER ignores the context,however, answering the question as if it had been askedin isolation.

The ability to follow a changing context and make ac-curate references to prominent objects is a fundamentalcharacteristic of human communication. In fact, abouthalf the words used in ordinary speech are found in DEFNPs (definitely determined noun phrases), the linguisticconstructions most often used to refer to objects in con-text. Note, for example, all the definitely determinednoun phrases underlined in the dialogue shown in listing4.

The need to understand context throws considerabledoubt on the idea of building natural-language interfacesto systems with knowledge bases independent of thelanguage-processing system itself. This is because the in-formation in the knowledge base may be needed simplyfor comprehension of a question. For example, to under-stand the phrase "the filter" in:

THE KENNEDY IS OWNED BY THE US

But they are incapable of dealing in a general way withmore logically complex notions, such as disjunction,quantification, implication, causality, and possibility.They act as if they were dealing with information about aworld containing a fixed number of objects and relation-ships among them, with the objects and relationships be-ing immutable.

Perhaps LADDER'S most important linguistic deficien-cy is its limited notion of linguistic context. With minor(though useful) exceptions, LADDER treats each input asif it were given in isolation. To perceive the problem, let'sconsider the question:

WHO ARE THE CAPTAINS OF THE US TANKERS?

IF I CHANGE THE OIL IN MY CAR, WHERE SHOULDI LOOK FOR THE FILTER?

it is necessary to know that automobiles use oil cleanedby a filter. Such knowledge makes possible the assump-tion that such a filter, the one on the user's car, is thereferent of "the filter." We cannot translate the questioninto a formal query to an auto-maintenance systemunless the translation system also has some informationabout the nature of auto maintenance.

Systems for Dealing with Dynamic Microworlds

SHRDLU, a system developed by Terry Winograd atMIT around 1970 (see reference 29), was one of the firstsystems to deal with some of the complexities of contextand address a domain of greater logical complexity than

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318 September 1981 © BYTE Publications Inc

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Figure 3: The microworld of blocks used by the SHRDLU pro-gram, which can manipulate objects in the microworld andanswer questions about them.

Listing 5: An actual conversation with the SHRDLU system.Associated images of the blocks microworld are given in figures3, 4, and 5.

1 — PICK UP A BIG RED BLOCK.

OK.

2 — GRASP THE PYRAMID.

I DON'T UNDERSTAND WHICH PYRAMID YOU MEAN.

3 — FIND A BLOCK WHICH IS TALLER THAN THE ONE YOU

ARE HOLDING AND PUT IT IN THE BOX.

BY "IT" I ASSUME YOU MEAN THE BLOCK WHICH IS

TALLER THAN THE ONE I AM HOLDING.

OK.

4 - WHAT DOES THE BOX CONTAIN?

THE BLUE PYRAMID AND THE BLUE BLOCK.

5 — WHAT IS THE PYRAMID SUPPORTED BY?

THE BOX.

6 — HOW MANY BLOCKS ARE NOT IN THE BOX?

FOUR OF THEM.

7 — WHY DID YOU CLEAR OFF THE RED BLOCK?

TO PICK IT UP.

8 — WHY DID YOU DO THAT?

BECAUSE YOU ASKED ME TO.

Figure 4: SHRDLU in the process of executing the command"PICK UP A BIG RED BLOCK".

can be handled by a conventional data-base managementsystem. An example of the types of interactions SHRDLUcan support is shown in listing 5. At the beginning of thedialogue, both user and system are talking about a smallmicroworld of blocks configured as shown in figure 3.

In interaction 1 of listing 5, SHRDLU is asked to pickup a big red block. Since there is only one such block inthe microworld, SHRDLU knows what to pick up. Com-plicating the situation, however, is a green block restingon the big red block. SHRDLU is forced to devise a planthat involves moving the simulated robot arm to thegreen block, lifting the green block, moving the block toa clear place on the table, placing the green block on thetable, releasing the green block, returning to the redblock, grasping the red block, and, finally, lifting it up.

Figure 5: The microworld after execution of the command"FIND A BLOCK WHICH IS TALLER THAN THE ONE YOUARE HOLDING AND PUT IT IN THE BOX". (This takes placeafter the action of figure 4.)

When this is done (after considerable computation time),the microworld configuration is as shown in figure 4 andSHRDLU responds with a simple "OK".

In interaction 2, the user asks SHRDLU to grasp "thepyramid." But there are two pyramids in the microworldcontext, and the linguistic context contains no clues tochoose between them. SHRDLU realizes that it cannotidentify the referent of "the pyramid" and tells the userso.

Interaction 3 reveals SHRDLU's ability to deal with afairly complex noun phrase containing a relative clauseand a comparative construction, and to handle prob-lematic words such as "one" and "it." The result of this

320 September 1981 © BYTE Publications Inc

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exchange is the microworld configuration shown in figure5. Note that the system has found it necessary to putdown the big red block it was holding.

Interaction 4 illustrates SHRDLU's question-answeringability. In the process of answering this question, the bluepyramid and blue block become the most salient objectsin the linguistic context.

In interaction 5, the user again makes use of the phrase"the pyramid." SHRDLU is now able to assign a specificreferent to the noun phrase. In particular, SHRDLU picksthe pyramid most recently mentioned in the conversa-tion.

In interaction 6, SHRDLU displays its ability to countand to handle negative constructions. Its response sug-gests a key limitation of SHRDLU—it assumes it knowseverything there is to know about the microworld. Inparticular, it assumes it knows about all the blocks. Tosee how this simplifies things, ask yourself how manypeople (or blocks) are not in the room you are in.

Interactions 7 and 8 show SHRDLU's rudimentaryability to deal with references to actions, rather than justto simple objects, and to recall the history of previous ac-tions and their causal linkage—essential skills for enter-ing into conversations about dynamic worlds.

Limitations of SHRDLU

The sample SHRDLU dialogue illustrates the system'scapacity to cope with dynamics in both the physical andlinguistic environments.

As observed by Wilks (see reference 28), SHRDLU'sapparent power derives largely from dealing with alogical, small, simple, closed microworld. Themicroworld is logical because all the facts about it can bestated in terms of first-order logic. This is fortunatebecause powerful problem-solving methods exist fordealing with bodies of facts in this form. But these power-ful methods are computationally expensive and becomeincreasingly inefficient as objects and facts proliferateand become more complex.

Fortunately for SHRDLU, its microworld containsfewer than a dozen objects, including the robot arm, andtheir interrelationships and the actions that can changethose interrelationships are relatively simple. For exam-ple, there are no messy objects like pieces of rope orbodies of water that can assume an infinite variety ofshapes or that can split or combine to form new objects.Furthermore, there are no cerebral creatures in themicroworld to complicate the picture by having wants,goals, beliefs, and the like.

Finally, the microworld is closed because it is assumedto be completely knowable. If the box is empty andSHRDLU plans to put the blue block in it, there is nopossibility that a gremlin will fill up the box with junk,turn it upside down, break it, nail a lid on it, or performany of infinitely many activities. If SHRDLU wants toknow if the box is empty, it simply tries to prove that itcontains something, and watches to see if the proof fails.Anything in the microworld that is knowable is provable,

MAIL ORDER DISCOUNTS

[apple computer

" Sales and ServiceAPPLE II PLUS 48K

$1,099

WE DISCOUNT PRICES — NOT SERVICEHARDWARE

SOFTWARE

DISK II DRIVE & INTERFACE 499

DISK II SECOND DRIVE 439

BASF5y2"DISKETTES(irj) 25

LANGUAGE SYSTEM W/PASCAL 379

INTEGER BASIC FIRMWARE CARD 149

APPLESOFT II FIRMWARE CARD 149

CENTRONICS PRINTER INTERFACE CARD . 179HIGH-SPEED SERIAL INTERFACE CARD .... 145

GRAPHICSTABLET 649

APPLE IEEE-488 INTERFACE CARD 339

M&RSUP-R-MODRF MODULATOR 25

MICROSOFTZ-80SOFTCARD SYSTEM 299

MICROSOFT 16K RAM CARD 169

VIDEX 80 COLUMN BOARD 295

HAYES MICROMODEM II 299

AMDEX 13" COLOR MONITOR 429

NEC 12" GREEN MONITOR 239

SILENTYPE PRINTER W/INTERFACE 350

EPSON MX-80 FT 649

QUME SPRINT 5/45 PRINTER 2499

APPLE DOS TOOLKIT 65

APPLE PLOT 60

TAX PLANNER 99

APPLE FORTRAN 159

APPLE PILOT 119

APPLE MUSIC THEORY 39

APPLEWRITER 65

DOW JONES PORTFOLIO EVALUATOR 45

DOW JONES NEWS & QUOTES REPORTER . 85

THE CONTROLLER 495

VISICALC (16 SECTOR) 159

VISIPLOT 149

VISITREND/VISIPLOT 215

DESKTOP PLAN II 159

BPI BUSINESS SOFTWARE (EACH) 335

SUPER TEXT II 125

PROGRAMMA APPLE PIE 110

EASYWRITER (80 COLUMNS) 219

D.B. MASTER 180

MICROSOFT FORTRAN 149

A

ATARI-

ATARI 800 16K

$759

ATARI 400 (16K) 350

410 PROGRAM RECORDER 69

810 DISK DRIVE 439

815 DUAL DISK DRIVE 1199

16K RAM MEMORY MODULE 89

MICROTEK 32K RAM 179

850 INTERFACE MODULE 159

830 ACOUSTIC MODEM 159

825 PRINTER (CENTRONIC 737) 699

JOYSTICK PAIR 18

LIGHT PEN 65

ATARI VISICALC 149

BASIC LANGUAGE 45

ASSEMBLER EDITOR 45

MUSIC COMPOSER 45

STAR RAIDER 39

COMPUTER CHESS 30

BASKETBALL 30

TELELINK 20

DATASOFT TEXT WIZARD 79

computer cicjg, inc.

Authorized Apple Dealer & Service Center

4688 CONVOY STREET, SAN DIEGO, CA 92111

(714) 565-4062

TO ORDER: Please send cashier's check, money order or personal check(allow 10 business days to clear). VISA and Master Card credit card serviceadd 3%. American Express credit card service add 5%. Shipping, handlingand insurance in U.S. add 3% (minimum $4). California residents add 6%sales tax. Foreign orders add 10% for shipping. Equipment is subject toprice change and availability. All equipment carries factory warranty. Storeprices differ from mail order prices. TELEX: 697120 DATAMAX-SDG

CALL OR WRITE FOR A COMPLETE PRICE LIST

322 September 1981 © BYTE Publications Inc

Circle 70 on inquiry card.

STATE OF THE ARTMEMORY SYSTEMS

512KB SINGLE BOARD MULTIBUS® MEMORY

State of the Art Multibus Memory Design.First to Offer 512KB on One Board.

The CI-8086 module is compatible with both 8 or 16 bit Multibus Systems.

PARITY — The CI-8086 generates and checks even parity with selectableinterrupt on parity error.

FAST ACCESS AND CYCLE TIME — Data access is 270NSEC and cycletime is 375 NSEC.

16 MEGA BYTE ADDRESSING — The memory is addressable in 16Kincrements up to 16 mega bytes.

LOW POWER CONSUMPTION — Total power consumption is under 8watts.

SINGLE QTY. PRICE:

128Kx9 $1350.

512Kx9 $2995.

Ill 11IIII

ijliiiiiiiiaiiui

iiiimii

256KB LSI 11/23® SINGLE DUAL WIDTH BOARD

The First and Only 256KB Memory on a Single Dual Board.

4 MEGABYTE ADDRESS FIELD — Most memories available forthe DECPDP 11/23 are only addressable to 256K bytes (18 address lines). TheCI-1123 is addressable to 4 mega bytes (22 address lines) so there is noneed to worry about obsolescence.

FAST ACCESS AND CYCLE TIME — With an access time of 240 NSECand cycle time of 400 NSEC one is insured the best throughput on the PDP11/23 system.

PARITY — The CI-1123 generates and checks parity for each byte ofmemory. Totally DEC compatible.

BATTERY BACKUP POWER CONSUMPTION — Power requirement forthe module is only 1.2 AMP from the 5 volt supply. The CI-1123 is easilyconfigured for battery back-up mode of operation requiring only 300MAfrom a single 5 V back-up supply for 256KB memory in the down state.

SINGLE QTY. PRICE:

32K x 18 $575.

128K x 18 $1925.

64K x 9 EXORCISER® I SINGLE BOARD MEMORY

For Exorciser I, Exorciser II and Rockwell System 65.

FAST ACCESS AND CYCLE TIME — Data access time is 225 NSEC andcycle time is 400 NSEC, allowing the unit to work as a static RAM at clockrates in excess of 1.5 mega hertz. For 2 mega hertz operation the board canbe easily configured to utilize a cycle stealing refresh operation.

ADDRESSING — On-board memory select is available in 4K incrementsup to 64K words of memory on either the VUA or VXA control inputs.

PARITY — On board even parity with output jumper select to the systembus as a parity error or non-maskable interrupt.

Complete board power consumption is under 7 watts.

SINGLE QTY. PRICE:Tested and bumtd in. Full year warranty.

64K x 9 $575.

DON'T ASK WHY WE CHARGE SO LITTLE, ASK WHY THEY CHARGE SO MUCH.

tf1 Chrislin Industries, Inc.

^^L*S 31352 Via Colinas • Westlake Village, CA 91362 • 213-991-2254

Multibus >■ ■ trademark of tin kitil Corp LSI II ii a Iraiemart of Digital Equipment Corp. EXOftriiar Ii a trademark of Motorola

Circle 61 on inquiry card.

BYTE September 1981 323

DYNACOMP

Quality software for*:

ATARI TRS-80 (Level II)**

PET NORTH STAR

APPLE II Plus CP/M Disks/Diskettes

CARD GAMES

BRIDGE 2.0 (Available for all computers) Price: $17.95 CasMtte/$21.95 Diskette

An all-inclusive version of this most popular of card games. This program both BIDS and PLAYSeither contract or duplicate bridge. Depending on the contract, your computer opponents will eitherplay the offense OR defense. If you bid too high, the computer will double your contract! BRIDGE 2.0provides challenging entertainment for advanced players and is an excellent learning tool for the bridgenovice. See the software review in 80 Software Critique.

HEARTS 1.5 (Available for all computers) Price: $15.95 Cassette/S 19.95 Diskette

An exciting and entertaining computer version of this popular card game. Hearts is a trick-orientedgame in which the purpose is not to take any hearts or the queen of spades, Play against two computeropponents who are armed with hard-to-beat playing strategies. HEARTS 1.5 is an ideal game for in-troducing the uninitiated (your spouse) to computers. See the software review in 80 Software Critique.

STUD POKER (Atari only) Price: $11 95 Cassette/S 15.95 Duke tie

This is the classic gambler's card game. The computer deals the cards one at a time and you (and thecomputer) bet on what you see. The computer does not cheat and usually bets the odds. However, itsometimes bluffsl Also included is a five card draw poker betting practice program. This package willrun on a 16K ATARI. Color, graphics, sound.

POKER PARTY (Available for till computers) Price: $17.95 Cmuetlc/$21.95 Diikette

POKER PARTY is a draw poker simulation based on the book, POKER, by Oswald Jacoby. This isthe most comprehensive version available for microcomputers. The party consists of yourself and sixother (computer) players. Each of these players (you will get to know them) has a difMftnt personalityin the form of a varying propensity to bluff or fold under pressure. Practice with POKER PARTYbefore going to that expensive game tonight! Apple Cassette and diskette versions require a 32 K (orlarger) Apple II.

CRIBBAGE 2.0 (TRS-80 only) Price: $14.95 C*uclte/$18.95 Diskette

This is simply the best cribbagc game available. It is an excellent program for the cribbage player insearch of a worthy opponent as well as for the novice wishing to improve his game. The graphics aresuperb and assembly language routines provide rapid execution. See the software review in 80 SoftwareCritique.

THOUGHT PROVOKERS

MANAGEMENT SIMULATOR (Atari, North Star and CP/M only) Price: $19.95 Cassette

S23.95 Diskette

This program is both an excellent teaching tool as well as a stimulating intellectual game. Based uponsimilar games played at graduate business schools, each player or team controls a company which man-ufacturers three products. Each player attempts to outperform his competitors by setting selling prices,production volumes, marketing and design expenditures etc. The most successful firm is the one withthe highest stock price when the simulation ends.

FLIGHT SIMULATOR (Available for all computers) Price: $17.95 Cassette 521.y5 Diskette

A realistic and extensive mathematical simulation of take-off. flight and landing. The program utilizesaerodynamic equations and the characteristics of a real airfoil. You can practice instrument approachesand navigation using radials and compass headings. The more advanced (Iyer can also perform loops,half-rolls and similar acrobatic maneuvers. Although this program does not employ graphics, it is ex-citing and very addictive. See the software review in COMPUTRONICS.

VALDEZ (Available for all computers) Price: $15.95 Casaette/$t9.95 Diskette

VALDEZ is a computer simulation of supertanker navigation in the Prince William Sound/ValdezNarrows region of Alaska. Included in this simulation is a realistic and extensive 256 x 256 elementmap, portions of which may be viewed using the ship's alphanumeric radar display. The motion of theship itself is accurately modelled mathematically. The simulation also contains a model for the tidalpatterns in the region, as well as other traffic (outgoing tankers and drifting icebergs). Chart yourcourse from the Gulf of Alaska to Valdez Harbor! See the software review in 80 Software Critique.

BACKGAMMON 2.0 (Atari, North Star and CP/M only) Price: $14.95 Cassette/$18.95 Diskette

This program tests your backgammon skills and will also improve your game. A human can competeagainst a computer or against another human. The computer can even play itself. Either the human orthe computer can double or generate dice rolls. Board positions can be created or saved for replay.BACKGAMMON 2.0 is played in accordance with the official rules of backgammon and is sure to pro-vide many fascinating sessions of backgammon play.

CHECKERS 3.0 (PET only) Price: $16.95 Casaette/$20.95 Diskette

This is one of the most challenging checkers programs available. It has 10 levels of play and allows theuser to change skill levels at any time. Though providing a very tough game at level 4-8, CHECKERS3.0 is practically unbeatable at levels 9 and 10.

CHESS MASTER (North Star and TRS-80 only) Price: $19.95 Cusctte/S23.95 Diskette

This complete and very powerful program provides five levels of play. It includes castling, en passantcaptures and the promotion of pawns. Additionally, the board may be preset before the start of play,permitting the examination of "book" plays. To maximize execution speed, the program is written inassembly language (by SOFTWARE SPECIALISTS of California). Full graphics arc employed in theTRS-80 version, and two widths of alphanumeric display are provided to accommodate North Starusers.

LEM LANDER <32K Apple Disk only) Price: $16.95 Diskette

Pilot your LEM LANDER to a safe landing on any of nine different surfaces ranging from smooth totreacherous. The game paddles are used to control craft attitude and thrust. This is a real-time high reschallenge I

FOREST FIRE! (Atari only) Price: 516.95 CasMtte/$20.95 Diskette

Using excellent graphics and sound effects, this simulation puts you in the middle of a forest fire. Yourjob is to direct operations to put out the fire while compensating for changes in wind, weather and ter-rain. Not protecting valuable structures can result in startling penalties. Life-like variables are providedto make FOREST FIRE! Very suspenseful and challenging. No two games have the same setting andthere are 3 levels of difficulty.

NOMINOES JIGSAW (Atari, Apple and TRS-80 only) Price: $16.95 Cassette/S20.9S DisketteA jigsaw puzzle on your computer! Complete the puzzle by selecting your pieces from a table consistingof 60 different shapes. NOMINOES JIGSAW is a virtuoso programming effort. The graphics aresuperlative and the puzzle will challenge you with its three levels of difficulty. Scoring is based upon thenumber of guesses taken and by the difficulty of the board set-up.

MONARCH (Atari only) Price: $11.95 Cassette/SI5.95 Diskette

MONARCH is a fascinating economic simulation requiring you to survive an 8-year term as your na-tion's leader. You determine the amount of acreage devoted to industrial and agricultural use, howmuch food to distribute to the populace and how much should be spent on pollution control. You willfind that all decisions involve a compromise and that it is not easy to make everyone happy.

CHOMP-OTHELLO (Atari only) Price: $11.95 Cass*tte/$ 15.95 Diskette

CHOMP-OTHELLO? It's really two challenging games in one. CHOMP is similar in concept to NIM;you must bite off part of a cookie, but avoid taking the poisoned portion. OTHELLO is the popularboard game set to fully utilize the Atari's graphics capability. It is also very hard to beat! This packagewill run on a I6K system.

DYNACOMP OFFERS THE FOLLOWING

Widest varietyGuaranteed qualityFastest deliveryFriendly customer serviceFree catalog24 hour order phone

AND MORE...

STARTREK 3.2 (Available for ail computers) Price: $11.95 Cassette/$ 15.95 Diskette

This is the classic Startrek simulation, but with several new features. For example, the Klingons nowshoot at the Enterprise without warning while also attacking starbases in other quadrants. TheKlingons also attack with both light and heavy cruisers and move when shot at I The situation is hecticwhen the Enterprise is besieged by three heavy cruisers and a starbase S.O.S. is received! The Klingonsget evenl See the software reviews in A.N.A.L.O.G., 80 Software Critique and Game Merchandising.

BLACK HOLE (Apple only) Price: $14.95 Cassette/SI 8.95 Diskette

This is an exciting graphical simulation of the problems involved in closely observing a black hole witha space probe. The abject is to enter and maintain, for a prescribed time, an orbit close to a small blackhole. This is to be achieved without coming so near the anomaly that the tidal stress destroys the probe.Control of the craft is realistically simulated using side jets for rotation and main thrusters for accelera-tion. This program employs Hi-Res graphics and is educational as well as challenging.

SPACE TILT (Apple and Atari only) Price: $10.95 Cms*«nc/$14.95 Diskette

Use the game paddles to tilt the plane of the TV screen to "roll" a ball into a hole in the screen. Soundsimple? Not when the hole gets smaller and smaller! A built-in timer allows you to measure your skillagainst others in this habit-forming action game.

MOVING MAZE (Apple Only) Price: $10.95 Cassetu/S 14.95 Diskette

MOVING MAZE employs the games paddles to direct a puck from one side of a maze to the other.However, the maze is dynamically (and randomly) built and is continually being modified. The objec-tive is to cross the maze without touching (or being hit by) a wall. Scoring is by an elapsed time in-dicator, and three levels of play are provided.

ALPHA FIGHTER (Atari only) Price: $14.95 Casaette/$1*.95 Diskette

Two excellent graphics and action programs in one! ALPHA FIGHTER requires you to destroy thealien starships passing through your sector of the galaxy. ALPHA BASE is in the path of an alien UFOinvasion; let five UFO's get by and the game ends. Both games require the joystick and get progressive-ly more difficult the higher you scorel ALPHA FIGHTER will run on 16K systems.

THE RINGS OF THE EMPIRE (Atari only) Price: $16.95 Casaette/$20.95 Diskette

The empire has developed a new battle station protected by rotating rings of energy. Each time youblast through the rings and destroy the station, the empire develops a new station with more protectiverings. This exciting game runs on 16K systems, employs extensive graphics and sound and can beplayed by one or two players.

INTRUDER ALERT (Atari only) Price: S16.95 Cas»elte/$20.95 Diskette

This is a fast paced graphics game which places you in the middle of the "Dreadstar" having just stolenits plans. The droids have been alerted and are directed to destroy you at all costs. You must find andenter your ship to escape with the plans. Five levels of difficulty are provided. INTRUDER ALERT re-quires a joystick and will run on 16K systems.

GIANT SLALOM (Atari only) Price: $14.95 CassctU/$lS.95 Diskette

This real-time action game is guaranteed addictive! Use the joystick to control your path throughslalom courses consisting of both open and closed gates, Choose from different levels of difficulty, raceagainst other players or simply take practice runs against the clock. GIANT SLALOM will run on 16K

systems.

TRIPLE BLOCKADE (Atari only) Price: $14.95 Cassette/Sid. 95 Diskette

TRIPLE BLOCKADE is a two-to-three player graphics and sound action game. It is based on theclassic video arcade game which millions have enjoyed. Using the Atari joysticks, the object is to directyour blockading line around the screen without running into your opponcnt(s). Although the concept issimple, the combined graphics and sound effect lead to "high anxiety".

GAMES PACK I (Available (or all computers) Price: $10.95 CasKtte/$14.95 Diskette

GAMES PACK I contains the classic computer games of BLACKJACK, LUNAR LANDER, CRAPS,HORSERACE, SWITCH and more. These games have been combined into one large program for easein loading. They are individually accessed by a convenient menu. This collection is worth the price justfor the DYNACOMP version of BLACKJACK.

GAMES PACK II (Available for all computers) Price: $10.95 Cassctte/$14.95 Diskette

GAMES PACK II includes the games CRAZY EIGHTS, JOTTO, ACEY-DUCEY, LIFE, WUMPUSand others. As with GAMES PACK I, all the games are loaded as one program and are called from amenu. You will particularly enjoy DYNACOMP's version of CRAZY EIGHTS.Why pay $7.95 or more per program when you can buy a DYNACOMP collection for just $10.95?

MOON PROBE (Atari and North Star only) Price: $11.95 Casaette/$15.95 Diskette

This is an extremely challenging "lunar lander" program. The user must drop from orbit to land at apredetermined target on the moon's surface. You control the thrust and orientation of your craft plusdirect the rate of descent and approach angle.

ADVENTURE

CRANSTON MANOR ADVENTURE (North Star and CP/M only) Price: $21.95 DisketteAt last! A comprehensive Adventure game for North Star and CP/M systems. CRANSTON MANORADVENTURE takes you into mysterious CRANSTON MANOR where you attempt to gatherfabulous treasures. Lurking in the manor are wild animals and robots who will not give up the treasureswithout a fight. The number of rooms is greater and the associated descriptions are much moreelaborate than the current popular series of Adventure programs, making this game the top in its class.Play can be stopped at any time and the status stored on diskette.

ABOUT DYNACOMP

DYNACOMP is a leading distributor of small system software with sales spanning the world(currently in excess of 40 countries). During the past two years we have greatly enlarged theDYNACOMP product line, but have maintained and improved our high level of quality andcustomer support. The achievement in quality is apparent from our many repeat customersand the software reviews in such publications as COMPUTRONICS, 80 Software Critiqueand A.N.A.L.O.G. Our customer support is as close as your phone. It is always friendly.The staff is highly trained and always willing to discuss products or give advice.

•ATARI, PET, TRS-80, NORTHSTAR, CP/M and IBM are registered tradenames and/ortrademarks,

"TRsso diskettes are not supplied with dos or basic. Circle 129 on Inquiry card.

BUSINESS and UTILITIES

SPESPmoSr(C,'T0,*) P*.:l».HDM.

SPELLGUARD a a revolunonary new product which increases the value of your current mrd processina system (WORD-mftJSSKJWS ELECTRIC PENCI1" TEX™ EDITOR .1 .„d other.). Written enSrel, in iSSSwbPhLLOUARD rapidly assois the u»;r in elirnin.ti.f ipehini md typographical erron by comparing each word or theten wins! ■ dictionary (expandable! of over 20,000 of the moil common English wordi. Word, appearing in the ten bui notfound in the dictionary are ■■ll.gged" for easy identification and correction. Moit adminiitralive staff familiar with word pro-cessing equipment will be able to use SPELLGUARD™ in only a few minutes.

MAIL LIST 2.2 (Apple, Alarl and North Sl»r diskette only) Price: S3« w

This program is unmatched in its ability to store a maximum number of addresses on one diskette (minimum of 1100 per disk-ette, more than 2200 for "double density" syslemsl). Its many features include alphabetic and rip code sorting, label printingmerging of file, and a unique keyword seeking routine which retrieves entries by a virtually limitless selection of user definedcodes. Mail List 2.2 will even find and delete duplicate entries. A very valuable program!

FORM LETTER SYSTEM (FLS) (AUrl, Apple and North Star dbkette only) PHce: S21.M

Use FLS to create and edit form letters and address lists. Form letters are produced by automatically inserting each address in-to a predetermined portion of your letter. FLS is completely compatible with MAIL LIST 2.2. which may be used to manaaeyour address Tiles.

FLS and MAIL LIST 2.2 are available as a combined package for S49.93.

SORcJ?7«?"",STW Prtt.iSM.MDUt.*

MJKin is * general purpose ion program written in 8080 assembly Language. Thij program will sort sequential data file*generated by NORTH STAR BASIC. Primary and optional secondary key, may be numeric or one to nine character stringsSORT1T ii easily used with files generated by DYNACOMP's MAIL LIST program and is very versatile in its capabilities forall other BASIC data Tile sorting.

PERSONAL FINANCE SYSTEM (Atari ud North Star only) PrtM- $«.« Dtakrtu

PFS is a single diskette, menu-oriented system composed or ten different programs. Besides recording your expenses and laxdeductible items, PFS will sort and summarize expenses by payee, and display information on expenditures by any of 26 userdefined codes by month or by payee. PFS will even produce monthly bar graphs of your expenses by category! This powerfulpackage requires only one disk drive, minimal memory (24K Atari. 32K North Star) and will store up 10 600 records per disk(and over 1000 records per disk by making a few simple chsnges 10 the programs). You can record checks plus cash expenses sothat you can finally set where your money goes and eliminate guesswork and tedious hand calculations.

FAMILV BUDGET (Apple only) PH„: m.w Diskette

The FAMILY BUDGET is a very convenient financial record-keeping program. You will be able to keep track of cash andcredit expenditures as well as income on a daily basis. You can record tax deductible items and charitable donations. TheFAMILY BL'DGET also provides a continuous record of all credit transactions. You can make daily cash and charge entries toany of 21 different expense accounts at well as to J payroll and tax accounts. Data is easily retrieved giving the user completecontrol over an otherwise complicated (and unorganized!) subject.

THE COMMUNICATOR (Atari only) Price: $49.95 Dfakttte

This software package contains a menu-driven collection of programs for facilitating efficient two-way communicationsthrough a full duplex modem (required for use). In one mode of operation you may connect to a data service (e.g.. TheSOURCE or MicroNet) and quickly load data such as stock quotations onto your diskette for later viewing. This greatly re-duces "connect time" and thus the service charge. You may also record the complete contents of a communications session.Additionally, programs written in BASIC, FORTRAN, etc. may be built off-line using the support text editor and later "up-loaded" to another computer, making the Atari a very "nan terminal. Even Atari BASIC programs may be uploaded. Fur-ther, a command file may be built off-line and used later ai controlling input for a time-share system. That is, you can set upyour sequence of lime-share commands and programs, and the Atari will transmit them as needed; batch processing. All thisadds up to saving both connect time and your time.

DYNACOMPalso supplies THE COMMUNICATOR with an Atari B 30 modem for acombined price of 1219.93. The modemis available separately for 1189.95.

TEXT EDITOR II (CP/M) Price: S29.95 Diskette/S3 3.45 Dkk

This is the second release version of DYNACOMP's popular TEXT EDITOR I and contains many new features. With TEXTEDITOR II you may build text files in chunks and assemble them for later display. Blocks of text may be appended, inserted ordeleted. Files may be saved on disk/diskette in right justified/centered format to be later printed by either TEXT EDITOR IIor the CP/M ED facility, Futher, ASCII CP/M files (including BASIC and assembly language programs) may be read by theeditor and processed. In fact, text files can be built using ED and later formatted using TEXT EDITOR II. All in all, TEXTEDITOR II is an inexpensive, easy to use, but very flexible editing system.

DOLE (Atari and North Star only) Prke: 519.95

This handy program allows North Star and Atari disk users 10 maintain a specialized data base of all files and programs in theslack of disks which invariably accumulates. DFILE is easy to set up and use. It will organize your disks to provide efficientlocating of the desired file or program.

FINDIT (North Star only) Price: $19.95

This is a three-in-one program which maintains information accessible by keywords of three types: Personal (eg; last name),Commercial (eg: plumbers) and Reference (eg: magazine articles, record albums, etc). In addition to keyword searches, therearc birthday, innivCTiary and appointment searches for the personal records and appointment Marches for ihe commercial re-cords. Reference records are accessed by a single keyword or by cross-referencing two or three keywords.

GRAFTX (TRS-M only) Price: S14.95 Casattte/Sli.95 Diskette

This unique program allows you to easily create graphics directly from the keyboard. You "draw" your figure using the pro-gram's extensive cursor controls. Once the figure is made, it it automatically appended to your BASIC program as a string var-iable. Draw a "happy face", call it H$ and then print it from your program using PRINT HI! This is a very easy way to createand save graphics.

EDUCATION

HODGE PODGE (Apple only, 48K Applesoft or Integer BASIC) Price: S19.95 Cassette/S23.W Dtaketic

Let HODGE PODGE be your child's baby sitter. Pressing any key on your Apple will result in a different and intriguing "hap-pening" related to the letter or number of the chosen key. The program's graphics, color and sound are a delight for childrenfrom ages 1V. to 9. HODGE PODGE is a n on -intimidating teaching device which brings a new dimension to the use of com-puters in education.

TEACHER'S PET I (Available for all computers) Price: $11.95 Cassette/$15.95 Diskette

This is the first of DYNACOMP's educational packages. Primarily intended for pre-school to grade 3. TEACHER'S PETprovides the young student with counting practice, letter-word recognition and three levels of math skill exercises.

MORSE CODE TRAINER (TRS-M only) Price: $12.95 Cassette/$16.95 Diskette

MORSE CODE TRAINER is designed to develop and improve your speed and accuracy in deciphering Morse Code. As such,MCT is an ideal software package for FCC (est practice. The code sound is obtained through the earphone jack of any stan-dard cassette recorder. You may choose the pitch of the tones as well as the word rate. Also, various modes of operation areavailable including number, punctuation and alphabet tests, as well as the keying of your own message. A very effective way tolearn cod el

MISCELLANEOUS

CRYSTALS (Atari only) Price: $ 9.HCasa*ttc/S13.95 Diskette

A unique algorithm randomly produces fascinating graphics displays accompanied with tones which vary as the patterns arebuilt. No two patterns are the same, and the combined effect of the sound and graphics are mesmerizing. CRYSTALS has beenused in local stores to demonstrate the sound and color features of the Atari.

NORTH STAR SOFTWARE EXCHANGE (NSSE) LIBRARY

DYNACOMP now distributes the 23 volume NSSE library. These diskettes each cistanding value for the purchase price. They should be part of every North Star userfor details regarding the contents of the NSSE collection.

AVAILABILITY

DYNACOMP software is supplied with complete documentation containing clear explanations and examples. Unless otherwisespecified, all programs will run within 16K program memory space (ATARI requires 24K). Except where noted, programs are avail-able on ATARI, PET. TRS-SO (Level 11) and Apple (Applesoft) cassette and diskette as well as North Star single density (doubledensity compatible) diskette. Additionally, most programs can be obtained on standard (IBM format) 8" CP/M floppy disks forsystems running under MBAS1C.

STATISTICS and ENGINEERING

D,GnVr'tT^,i™<AVtlllb,e '?' It coJmP°ter,) «■» S» « CwmiM DiaketuDIGITAL FILTER is a comprehensive data processing program which permits the user to design his own filter function orchoose from a menu of filter forms. The filler forms are subsequently convened into non-recursive convolution coefficientswhich permit rapid data processing. In the explicit design mode the shape of the frequency transfer function is specified bydirectly entenng points along the desired filler curve. In the menu mode, ideal low pass, high pass and bandpass filters may beapproximated to varying degrees according to the number of points used in the calculation. These filters may optionally also besmoothed with a Hanning function. In addition, multi-stage Butterworth filters may be selected. Features of DIGITALFILTER include plotting of the data before and after filtering, as well as display of the chosen filter functions. Also included it data storage, retrieval and editing procedures.

DATA SMOOTHER (Not available for Atari) f^, $„.„ ammftuM Dtakeite

This special data smoothing program may be used to rapidly derive useful information from noisy business and engineeringdata which are equally spaced. The software features choice in degree and range of fit. as well as smoothed first and secondderivative calculation. Also included is automatic plotting of the input data and smoothed results.

FOURIER ANALYZER (Available for all computer*) putt: $I6.M Caaaetta/Stt.95 Diskette

Use this program to examine the frequency spectra or limited duration signals. The program features automatic scaling andplotting of the input data and remits. Practical applications include the analysis of complicated patterns in such fields as elec-tronics, communications and business.

TFA (Transfer Function AnaryMr) p^. mjs caaa«m/S23.w Diskette

This is a special software package which may be used to evaluate the transfer functions of systems such as hi-fi amplifiers andfilters by examining their response to pulsed inputs. TFA is a major modification of FOURIER ANALYZER and contains anengineenng-onented decibel versus log.frequency plot as well as data editing features. Whereas FOURIER ANALYZER is de-signed for educational and scientific use, TFA is an engineering tool. Available for all computers.

HARMONIC ANALYZER (Available for all computers) Me.: $m.m Casaette/Sll.W Diskette

HARMONIC ANALYZER was designed for the spectrum analysis of repetitive waveforms. Features include data file genera-tion, editing and storage/retrieval as well as data and spectrum plotting. One particularly unique facility is that the input dataneed not be equally spaced or In order. The original data is sorted and a cubic spline interpolation is used to create the data filerequired by the FFT algorithm.

FOURIER ANALYZER, TFA and HARMONIC ANALYZER may be purchased together for a combined price of S49 95(three cassettes) and SS9.95 (three diskettes).

REGRESSION I (Available for ail computer*) price: $19.95 Caaactu/$13.95 Dtaketic

REGRESSION 1 is a unique and exceptionally versatile one-dimensional least squares "polynomial" curve fitting program.Features include very high accuracy; an automatic degree determination option; an extensive internal library of fitting func-tions; data editing; automatic data and curve plotting; a statistical analysis (eg: standard deviation, correlation coefficient,etc.) and much more. In addition, new fits may be tried without reentering the data. REGRESSION 1 is certainly the corner-stone program in any data analysis software library.

REGRESSION II (PARAFTT) (Available for all computers) Price: $19.95 Ctaaene/S13.95 Diskette

PARAF1T is designed to handle those cases in which the parameters are imbedded (possibly nonlinearly) in the fitting func-tion. The user simply inserts the functional form, including the parameters (A(l), Ap), etc.) as one or more BASIC statementlines. Data and results may be manipulated and plotted as with REGRESSION 1. Use REGRESSION 1 for polynomial fitting,and PARAF1T for those complicated functions.

MULTILINEAR REGRESSION (MLR) (Available for all computers) Price: $24.95 Cassette/S2>.95 Diskette

MLR is a professional software package for analyzing data sets containing two or more linearly independent variables. Besidesperforming the basic regression calculation, this program also provides easy to use data entry, storage, retrieval and editingfunctions. In addition, the user may interrogate the solution by supplying values for the independent variables. The number ofvariables and data size is limited only by the available memory.

REGRESSION I, II and MULTILINEAR REGRESSION may be purchased together for $51.95 (three cassettes) or $63.95

(three diskettes).

ANOVA (Available for ail computers) Price: $39.95 Caswtte/S43.95 Dbkette

In the past the ANOVA (analysis of variance) procedure has been limited to the large mainframe computers. NowDYNACOMP has brought the power of this method to small systems. For those conversant with ANOVA, the DYNaS?OMPsoftware package includes the 1-way, 2-way and N-way procedures. Also provided are the Yates 2**p factorial designs. Forthose unfamiliar with ANOVA, do not worry. The accompanying documentation was written in a tutorial fashion (by a pro-fessor in the subject) and serves as an excellent introduction to the subject. Accompanying ANOVA is a support program forbuilding the data base. Included are several convenient features including data editing, deleting and appending.

BASIC SCIENTIFIC SUBROUTINES, Volume I (Not available for Atari)

DYNACOMP is the exclusive distributor for the software keyed to the popular text fi,4S/C Scientific Subroutines. Volume Iby F. Ruckdeschel (see the BYTE/McOraw-HiU advertisement in BYTE magazine, January 1981). These subroutines havebeen assembled according to chapter. Included with each collection is a menu program which selects and demonstrates eachsubroutine.

Collection #1: Chapters 2 and 3: Data and function plotting, complex variables

Collection HI: Chapter 4: Matrix and vector operations

Collection >f3: Chapters 5 and 6: Random number generators, series approximationsPrice per collection: $14.95 Cassette/S1B.95 DisketteAll three collections are available for $39.95 (three cassettes) and $49.95 (three diskettes).

Because the text is a vital part of the documentation, BASIC Scientific Subroutines, Volume I is available from DYNACOMPfor $19.95 plus 75* postage and handling.

ROOTS (Available for all computers) Price $10.95 Cassette/$14.95 Dbkette

In a nutshell, ROOTS simultaneously determines all the zeroes of a polynomial having real coefficients. There is no limit onthe degree or the polynomial, and because the procedure is iterative, the accuracy is generally very good. No Initial guesses arerequired as input, and the calculated roots are substituted back into the polynomial and the residuals displayed.

ACTIVE CIRCUIT ANALYSIS (ACAP) (48K Apple only) Price: S13.M/SM.W Dbkette

ACAP is the analog circuit designer's answer to LOGIC SIMULATOR. With ACAP you may analyze the response of an ac-tive or passive component circuit (e.g., a transistor amplifier, band pass filter, etc.). The circuit may be probed at equal steps infrequency, and the resulting complex (i.e., real and imaginary) voltages at each component juncture examined. By plotting themagnitude of these voltages, the frequency response of a filter or amplifier may be completely determined with respect to bothamplitude and phase. In addition. ACAP prints a statistical analysis of the range of voltage responses which result fromtolerance variations in the components.

ACAP is«descriptioiof every c

sy to learn and use. Simply describe the circuit in terms of the elements and their placement, and execute. Circuitmay be saved onto cassette or diskette to be recalled at a later time for execution or editing. ACAP should be partcuit designer's program library.

LOGIC SIMULATOR (Apple only; 4SK RAM) Price: $24.95 Qwsette/S2I.W Diskette

With LOGIC SIMULATOR you may easily test your complicated digital logic design with respect to given set of inputs todetermine how well the circuit will operate. The elements which may be simulated include multiple input AND, OR, NOR,EXOR, EXNOR and NAND gates, as well as inverters, J-K and D flip-flops, and one-shots. The response of the system isavailable every clock cycle. Inputs may be clocked in with varying clock cycle lengths/displacements and delays may be intro-duced to probe for glitches and race conditions. At the user's option, a timing diagram for any given set of nodes may be plot-ted using HIRES graphics. Save your breadboarding until the circuit is checked by LOGIC SIMULATOR.

LOGIC DESIGNER (North Star and CP/M only) Price: $34.95 Dbkette

LOGIC DESIGNER is an exceptional Computer Aided Design (CAD) program. With it you may convert a large and compli-cated digitial truth table (the functional specification) into an optimized Boolean logic equation. This equation may then beeasily converted into a circuit design using either NAND or AND/OR gates. Operationally, LOGIC DESIGNER is composedof a BASIC program which calls in a machine language routine to reduce execution time. Example: For a 7 variable by 127 linetable, the processing time is only two minutes. LOGIC DESIGNER is clearly a fast and powerful tool for building digital cir-cuitry.

ORDERING INFORMATION

All orders are processed and shipped within 48 hours. Please enclose payment with order and include the appropriate computer in-formation. If paying by VISA or Master Card, include all numbers on card.

Shipping aad Handling Charges

Within North America: Add $1.50

Outside North America: Add 10*7. (Air Mail)

Delivery

All orders (excluding books) a

1 sent First Class.

I" CP/M Disks

Add 12.30 to the listed diskette price for each

Microsoft MBASIC or BASIC-80.

programs. Dealer discount schedules are available upon request.

floppy disk (IBM soft sectored CP/M format). Programs n

" CP/M disks is also available on SW" disks. North Star format.

e dealer. Write for detailed descriptions of these and other programs from

DYNACOMP, Inc.

1427 Monroe Avenue

Rochester, New York 14618

24 hour order phone: (716)586-7579 recording

Office phone (9AM-5PM EST): (716)442-8960

New York Stale resident, picas* add 7* NV5 sates laa.

Players: customer, server, cashier

Props: restaurant, table, menu, food, check, payment, tip

Actions:

1. Customer goes to restaurant

2. Customer goes to table

3. Server brings menu

4. Customer orders food

5. Server brings food

6. Customer eats food

7. Server brings check

8. Customer leaves tip for server

9. Customer gives payment to cashier10. Customer leaves restaurant

Table 1: A restaurant script for the SAM program.

and, therefore, anything that cannot be proved must befalse.

The world that people deal with in everyday conversa-tions is extensive, complex, and largely unknown andunknowable. To use natural language to converse aboutthe real world, more sophisticated methods are needed.

Systems with Knowledge of Ordinary Situations

One of the more interesting attempts to deal with or-dinary human situations, in contrast to interfacing with adata base or a model of a microworld, was made byRoger Schank and Robert Abelson, aided by theirstudents at Yale University. Their system, SAM (forScript Applier Mechanism), as described in reference 22,

was built to cope with certain kinds of everyday prob-lems. For example, the system is told the following story:

John went to a restaurant.He ordered the lamb.He paid the cashier andleft the restaurant.

Then the system is asked:

What did John eat?

It might seem trivial for a system to answer that John atethe lamb—but nowhere in the story is this explicitlystated. Nor is it directly deducible from what was said.To understand the story, the system must have bothknowledge of what usually happens in restaurants and anability to apply that knowledge to particular situations.

Schank and Abelson encoded SAM's knowledge abouteveryday situations in formal constructs called scripts.The information contained in a script about restaurants isshown in table 1. It includes a list of players who par-ticipate in the normal routine of a restaurant, a list ofprops supporting the action, and a sequence of genericactions that characterize what usually happens when acustomer visits a restaurant.

The information in this script can be used to support avariety of commonsense-reasoning tasks, including a re-ply to the question, "What did John eat?" The processingis as follows: the system identifies "John went to arestaurant" with action 1 from the script. In doing this,John is assigned the role of the customer. The systemidentifies "He ordered the lamb" with action 4, assigningthe role of food to "the lamb." (Notice that with "he"referring to John, the customer is the same in both actions1 and 4.) "He paid the cashier" is identified with action 9and "[he] left the restaurant" with action 10.

Although not all the actions in the script were explicitlymentioned, it is reasonable (but not strictly necessary) toassume that they happened nonetheless. In particular, ac-tion 6, the customer eating the food, probably did hap-pen. Moreover, because the entities playing the variousparts in the script remain constant throughout its enact-ment, the system assumes that, for this particular visit tothe restaurant, the customer in each action is John andthe food is "the lamb." Therefore, action 6 particularizesto "John ate the lamb," providing the answer to theoriginal question.

Information in scripts can be used for more than justanswering questions; it can also be used to produce"paraphrases" of a story. For example, SAM can convertthe original story:

John went to a restaurant. He sat down. He got mad.He left.

into the "paraphrase":

John was hungry. He decided to go to a restaurant. Hewent to one. He sat down in a chair. A waiter did not

326 September 1981 © BYTE Publications Inc

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go to the table. John became upset. He decided he wasgoing to leave the restaurant. He left it.

This restatement is not a true paraphrase because it addsmany details based on speculation about what happened.But such an ability to speculate on the basis of knowledgeabout how our everyday world is structured is the veryfeature that makes SAM interesting.

Much of SAM's knowledge is not about naturallanguage at all, but about our everyday world. SAMdemonstrates that understanding natural-language storiesabout mundane actions requires more than a knowledgeof language—it requires a knowledge of the world. Themore language is studied, the more apparent it becomesthat fluent communication in natural language is a pro-cess of the total intellect. Language, thought, andknowledge are inextricably intertwined.

Limitations of SAM

SAM's scripts provided one of the first mechanisms ina language processor for dealing with the structured se-quences of actions that make up much of ordinary life,but they suffer from a number of limitations:

• Only a single object can serve the role of player orprop. This makes it impossible to handle stories aboutrestaurants with many tables, customers, or servers. Theproblem of figuring out what the phrase "the customer"refers to becomes trivial because there can be only onecustomer.

• The actions in a script follow a strict linear sequence,making it impossible to deal with alternative possibilities,simultaneous or overlapping actions, or a repetition ofactions.

• It is difficult to determine which particular script orscripts are appropriate for understanding a given story.

The TDUS System

The SHRDLU example discussed earlier suggested thepotential richness of interactive dialogue in context. TheSAM example showed how inference (ie: filling in theblanks regarding what was implied, as well as what wasexplicitly stated) is essential in understanding naturallanguage. To determine how knowledge-based inferenceand dialogue management interact, as well as worktoward solving a problem of practical value, a group ofresearchers at SRI International investigated cooperative,task-oriented, man-machine dialogue (see reference 19).They developed a system called TDUS (Task-OrientedDialogue Understanding System), which had the goal ofcommunicating with a human apprentice about repairoperations on electromechanical equipment. The keyresearch problems considered concerned how to encodeknowledge about the repair operations and how to followthe context of a dialogue as the apprentice moved fromtask to task in the course of performing a repair opera-tion.

In TDUS, information about how various tasks can beperformed is recorded in data structures called pro-cedural networks (see reference 21), which can be viewed

328 September 1981 © BYTE Publications Inc

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Figure 6: A procedural net for the process of installing a pumpfor an air compressor.

Figure 7: A procedural net expanding an action referenced infigure 6.

A

TASK

X

subtask\_

_ /SUBTASK>

. s r

\ B ,

TASK

SUBTASKA

SUBTASKB

TTTT TTTTTTT TTTTTT TTTTTTTTTTTTT TTTTTTT TTTTTTT TTTTTTTTTT TTTTTTTTTTT TTTTTT.

A AAAAAAAAAAA AAAAA AAAAAAAAAAA AAAAA AAA AAAAAAAAAAAAAA AAAAA AAAAAAAAA AAAAAAAAAAAAAAAAAAAAA AAAAAAAAA AAAAAA AAA AAAAAAAAA AAAAAAAAAA AAAAAAA AAAA AAAAAAA.

TTTT TTTTTT TTTTTTTT TTTTTTTTTT TTTTTTTTTTTT TTTTT TTTTTT.

BBBBBB BBBBBB BB BBBBBBBBBBBBB BBBBB BBBBBBBBB BB BBBBBBBBBBBBBBB BBBBBBB BBB BBBBB BBBBBBBBBBB BBBBBBBB BBBBBBBBBBB BBBBBBBB BBBBBBBBB BBBBB.

Figure 9: The structure of a task (top) is reflected in the structureof an English dialogue about the task (bottom). When discussingthe task, descriptions referring to the overall task (the twoparagraphs of the letter T) are interspersed with the paragraphsof text referring to subtask A and subtask B.

SECUREWITH BOLTS

Figure 8: A procedural net that contains actions repeated in aloop.

as generalizations of scripts. Simplified procedural netsare shown in figures 6, 7, and 8. For example, the net offigure 6 indicates how installing a pump for an air com-pressor can be divided into a number of subtasks. Thefirst subtask is to attach the pump to the platform. Oncethis is done, either the aftercooler elbow or the brace isinstalled. Once the aftercooler elbow is installed, theaftercooler is installed. Once the brace is installed, thepulley is installed. When both the aftercooler and pulleyhave been installed, regardless of the order accomplished,the task of installing the pump is complete.

Much like a script, the procedural net associates an ac-tion with a number of subactions. However, as opposedto the strict sequence of actions in a script, the proceduralnet imposes only a partial ordering on subactions.Moreover, subactions are usually associated with pro-cedural nets of their own, which specify in yet greaterdetail how tasks are divided. For example, the "attachpump" action referred to in figure 6 is described further infigure 7, while the "secure with bolts" action referred toin figure 7 is described further in figure 8. The net offigure 8 contains a loop specifying the repeated procedureof using a wrench to tighten each bolt.

As mentioned earlier, a major problem for natural-language processing systems is following the dialoguecontext and being able to ascertain the referents of nounphrases by taking the context into account. In preparingto build the TDUS system, Barbara Grosz collected anumber of dialogues between human experts and appren-tices performing repair tasks (see reference 8). After con-structing procedural nets for the tasks, it was discoveredthat, as a general rule, the structure of task-orienteddialogues closely follows the structure of the netsrepresenting the division of the task itself. As shown infigure 9, if a task divides into subtasks A and B, thedialogue tends to start with general information aboutthe overall task, then enters a subdialogue about subtaskA followed by a subdialogue about subtask B.

330 September 1981 © BYTE Publications Inc

***** •tr-tr-it-ir-tr-tr-tr-ir-tr-tftrir-it-ir-fr-ir'tr'tr-tr-tr-tr-triftr-tr-tr ir-tt-k-tt-tctr-tr-k-tr-tr-tr-tr-tr-ttick-tr-trit -trie

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Of greater interest is the fact that referential expres-sions tend to refer to objects salient in the current subtaskor higher in the task hierarchy, but generally do not referto objects in sibling subtasks. For example, if in thedialogue of figure 9 a wrench Wi is mentioned in one ofthe initial utterances before entering subdialogue A, andif a second wrench W2 is mentioned within subdialogueA, the phrase "the wrench" uttered in subdialogue B morelikely refers to Wi than to W2—even though W2 wasmentioned more recently. (This is clearly in violation ofthe rule used by SHRDLU in interaction 5 of listing 3.) Inthis regard, referential expressions in natural languagestend to follow much the same conventions as do variablereferences in block-structured programming languagessuch as ALGOL and Pascal. But the block structure ofnatural language is not indicated explicitly.

TDUS's ability to follow real-world tasks and deal withshifts in both the linguistic and physical context is il-lustrated in the transcript of listing 6, which relates to in-formation contained in the nets of figures 6 through 8.

In interaction 1, the apprentice sets the stage by speci-fying what action is being done. This allows TDUS topinpoint the location in the INST ALL-PUMP net wherethe apprentice appears to be. In interaction 2, the appren-tice refers to a bolting action and a wrench used in thataction. Neither of these is in the top-level representationof the ATTACH-PUMP net, but they both occur in thesubordinate net of figure 8. TDUS finds this subnet anddetermines that no other relevant subnet refers to a dif-

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ferent bolting action. Therefore, the system responds byspecifying the wrench mentioned in the net shown infigure 8.

In interaction 3, the apprentice asks for the location ofthe bolts. TDUS does not operate under the closed-worldassumption and realizes that there are some things it doesnot know. Luckily, the user finds the bolts in interaction4.

In interaction 5, the apprentice refers to "the wrench."TDUS determines that the reference is to the wrench men-tioned in interaction 2 and tells the apprentice its loca-tion. In interaction 6, TDUS resolves "it" as pertaining tothe same object.

In interaction 7, the apprentice tells TDUS that thepump-attaching operation is completed. The system in-fers from this that all the constituent subtasks have alsobeen done. To make sure, it reviews these assumptionsfor the apprentice. This filling in of intermediate steps ismuch like that in the SAM examples.

In interaction 8, the apprentice poses a logically com-plex question involving the modal concept "should."TDUS's rudimentary notion of "should" interprets thequestion as asking whether the action mentioned is corn-

Listing 6: An actual conversation with the TDUS system. Withthis system, the computer supervises a task performed by ahuman apprentice. Human input is shown in boldface.

1 — I AM ATTACHING THE PUMP.

OK.

2 — WHICH WRENCH SHOULD I USE TO BOLT IT?

USE THE BOX-END WRENCH.

3— WHERE ARE THE BOLTS?I DON'T KNOW.

4— I FOUND THEM.OK.

5— WHERE IS THE WRENCH?

THE BOX-END WRENCH IS ON THE TABLE.

6 — I FOUND IT.

OK.

7 — I ATTACHED THE PUMP.

OK.THE FOLLOWING HAS BEEN ASSUMED:YOU PUT THE PUMP AT THE PLATFORM. YOU BOLTED THEPUMP TO THE PLATFORM WITH THE BOLTS.

8 — SHOULD I INSTALL THE PULLEY NOW?

NO.THE NEXT STEP IS:INSTALL THE AFTERCOOLER ELBOW ON THE PUMP

ORINSTALL THE BRACE ON THE PUMP.

9 — I'M DOING THE BRACE NOW.

OK."DO" IS ASSUMED TO MEAN:

YOU ARE INSTALLING THE BRACE.10— I'VE DONE IT.

OK."DO" IS ASSUMED TO MEAN:

YOU INSTALLED THE BRACE.THE FOLLOWING HAS BEEN ASSUMED:YOU PUT THE BRACE AT THE PUMP.YOU SECURED THE BRACE.11 - I'VE INSTALLED THE PULLEY.OK.

332 September 1981 © BYTE Publications Inc

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patible with one of the possible next steps in theprocedural-net model of the task at hand. Since it is not,TDUS answers in the negative, but goes on to outline therange of acceptable alternatives at this point in the pro-

cess.

Interaction 9 is of considerable interest in that it con-tains the pro-verb "do." This is a reference to some actioninvolving the apprentice and the brace. But the action isnot completely specified. By examining the proceduralnet, TDUS determines that the likely thing to do with abrace in this context is to install it—so TDUS makes thatassumption and reports it to the apprentice.

Interaction 10 demonstrates TDUS's ability to com-prehend an extreme case of contextually dependent use oflanguage. Neither "done" nor "it" conveys much infor-mation. Here, "it" refers not to some object in the world,but to an action previously alluded to by the phrase "do-ing the brace."

Limitations of TDUS

TDUS exhibits a reasonable understanding of the in-terplay among various types of possible real-world ac-tions, and it can follow the evolution of particular instan-tiations of those actions. However, it has little under-standing of the goals and motivations of the apprenticewith whom it holds conversations.

An exchange well beyond the capability of TDUS isshown in the following actual dialogue between a noviceand an expert mechanic:

1. WHAT DO I DO NEXT?

REMOVE THE BOLT.

2. HOW DO I GET IT OFF?

USE THE RATCHET WRENCH.

3. WHAT'S A RATCHET WRENCH?

IT'S ON THE TABLE.

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334 September 1981 © BYTE Publications Inc

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BYTE September 1981 335

Figure 10: A sentence that conveys different information to dif-ferent people.

The key point to note here is that, in interaction 3, theresponse is not a direct answer to the question. If TDUScould answer this question at all, it would likely respondwith a dictionary definition such as: "a tool for graspingand turning the head of a bolt, consisting of fixed or ad-justable jaws mounted on a pawl that is engaged by thetoothed end of a gripping bar." The person whoanswered query 3 understood the motivation behind thequestion. It was asked so the inquirer would know thedescription of a ratchet wrench, so he could find it, so hecould grasp it, and so he could use it to remove the bolts.Understanding the inquirer's hierarchy of goals, therespondent addresses one of the goals closer to the end ofthe chain (finding the wrench). The cooperative respon-dent saves the inquirer the trouble of taking the step oflocating the wrench from its description.

Beyond Current Systems

Researchers in computational linguistics have onlyrecently begun to appreciate the impact on natural-language communication of what the participants in aconversation know about each other's knowledge,beliefs, plans, and goals. To appreciate the importance ofsuch knowledge, consider the situation illustrated infigure 10.

A young mother is giving a birthday party for Junior,and Grandma has come to help. Grandma's task is tolight the candles on the cake, so she asks, "When shall Ilight the candles?" The mother replies, "We'll have thecake as soon as the children wash their hands," which in-forms Grandma that it will be about five minutes. Themother knows that the big-eared kids are listening, so shephrases her response to serve multiple purposes for multi-ple audiences. With her one statement, she tells Grandmawhen the candles need to be lit and, in a nice, indirectway, tells the children to get their dirty hands washed.She knows that her response to Grandma will serve thispurpose because she knows that:

• the children want the cake

• her response to Grandma will convey to them the infor-mation that all that stands in the way of their getting it isto wash their hands

• if they know that all that stands in the way of their get-ting cake is to wash their hands, they will perform theritual forthwith

• it takes them about five minutes to wash their hands

Similarly, Grandma now knows that she should lightthe candles in five minutes because she knows that themother knows all the circumstances just outlined and thatthe mother knows Grandma knows that the motherknows it. Thus, Grandma infers that the mother expectsher to understand that the children are being told to washtheir hands, that they are motivated to do it right away,and the result five minutes later will presumably bewashed hands reaching avidly for cake.

No system is currently capable of handling languagewith this level of sophistication, but a number of re-searchers are actively engaged in studying the variousproblems involved; see references 3, 5, 6, 7, 13, 14, 16,18, 23, and 27. Much of this work is concerned with thedifficulties of interpreting not just what is literally said,but also of establishing the underlying intention. Shouldthis work succeed, systems may be capable of the kind ofreasoning indicated in listing 7.

The examples of the locked toolbox and the birthdayparty support a central point: communicating in naturallanguage is an activity of the total intellect. Seen in broadperspective, the use of natural language can be placed in ageneral framework that seeks to account for all humanactivity. Within this framework, humans are seen as in-telligent beings motivated by complex sets of goals theyseek to fulfill by planning, executing, and monitoring se-quences of actions—some of which are physical, somelinguistic. That is, uttering a sentence is just as much anaction as taking a step or taking a bath. Whereas theusual purpose of a physical action is to alter the physicalworld, the usual purpose of a linguistic action is to alter

Listing 7: An imaginary conversation with a TDUS-like systemshowing the possible behavior of a computer system that reactsto human needs in a way not currently possible by existingsystems.

USER: THE TOOLBOX IS LOCKED.

SYSTEM: (WHY IS HE TELLING ME THIS? I ALREADY KNOWTHE BOX IS LOCKED.)

(I KNOW THE USER NEEDS TO GET IN. PERHAPS HEIS TELLING ME THE BOX IS LOCKED BECAUSE HEBELIEVES I CAN SOMEHOW HELP.)(TO GET IN TAKES A KEY. THE USER KNOWS THISAND KNOWS I KNOW IT. THE KEY IS IN THEDRAWER. IF THE USER KNEW THIS HE WOULDJUST UNLOCK THE BOX. THEREFORE, HE MUSTNOT KNOW IT.)

(I CAN MAKE HIM COME TO KNOW IT BY SAYING"THE KEY IS IN THE DRAWER." I AM SUPPOSED TOHELP. I WILL SAY IT.)THE KEY IS IN THE DRAWER.

336 September 1981 © BYTE Publications Inc

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iS

the mental states of the hearers. In the latter case, thedesired modification may be to add knowledge, change amood, or establish a new goal for the hearers.

A speaker may plan and execute linguistic actions tochange some aspect of a hearer's mental state, not as anend in itself, but as part of an overall plan to achievesome more ambitious end. Just as a child might push overthe first domino of a long row to make them all tumble insequence, a lifeguard at the beach may yell "Shark!" atswimmers to set off a chain of reasoning in their mindsthat will result in a mad dash for the shore, which is thelifeguard's intended mechanism for accomplishing theprimary goal of preserving life.

Given this view of how language works, it becomesless important to ask what a given utterance means (whatdoes "Shark!" mean?) and more important to ask aboutthe effect it produces. People in advertising have an ex-plicit understanding of this concept, but all of us use itimplicitly when we understand the agony conveyed bythe string of curses uttered by the handyman whosmashes his finger, and when we realize that our friend'squestion, "Do you know the time?," deserves more thana "yes" or "no" answer.

The understanding of poetry can even be cast in thismold. The poet deliberately triggers certain chains of in-ference in readers. Indeed, an important element in theappreciation of poetry is the reader's awareness of the in-terplay among the inference chains followed, the chainsfollowed partway that turn out to be not quite ap-propriate, and the surface meanings of the sentences com-prising the poem itself. To experience this, just considerthe title of T S Eliot's poem, "The Love Song of J. AlfredPrufrock."

The Nature of Natural-Language Research

The previous sections discussed the capabilities andlimitations of specific natural-language processingsystems. But it must be recognized that these systems aremerely spin-offs of the underlying science. In essence,most researchers in this field do not think of themselvesas engineers seeking to evolve better natural-languageprocessing systems, but rather as scientists concernedwith the following related problems:

• identification of sources of knowledge necessary forunderstanding or generating natural language

• discovery or devising of mechanisms for encoding andapplying such knowledge in a mechanical device

• creation of integration frameworks to control and coor-dinate the application of a variety of knowledge sources

Once sources of knowledge have been identified, wholesubdisciplines come into being to study the associatedbodies of knowledge, their structure, and methods fortheir computerization. Some of the major knowledgesources are discussed below.

Lexical knowledge concerns individual words, theparts of speech they belong to, and their meanings.

Syntactic knowledge has to do with the grouping ofwords into meaningful phrases. For example, syntactic

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knowledge distinguishes between the following twosentences:

NAME THE PARTS OF THE PUMP THAT WASFIXED BY JOE.

NAME THE PARTS OF THE PUMP THAT WEREFIXED BY JOE.

In particular, it is the syntactic number distinction be-tween WAS and WERE that indicates whether the pumpor the parts were fixed.

Syntactic ambiguity is a common source of trouble innatural-language processing systems. For example, deci-sions about where to associate the prepositional phrase"on the table" in:

PUT THE HAMMER IN THE TOOLBOX ON THETABLE.

can lead to any one of the interpretations:

PUT THE HAMMER THAT IS IN THE TOOLBOX

ONTO THE TABLE.

PUT THE HAMMER INTO THE TOOLBOX THAT

IS ON THE TABLE.

WHILE YOU STAND ON THE TABLE, PUT THE

HAMMER INTO THE TOOLBOX.

Compositional semantics is the knowledge of how tocompose the literal meaning of large syntactic units fromthe semantics of their subparts. Its utility is illustrated bythe pair of sentences:

THE MAN HELD THE NUT (with a wrench).THE WRENCH HELD THE NUT.

These two sentences are syntactically identical, but thesubject of the first sentence is the agent of the action"hold," whereas the subject of the second is the instru-ment used by the agent. The lexical entry for the verbHOLD indicates that it is used to refer to actions in whichan agent (usually a person) using an instrument exerts aforce on some physical object. The syntactic subject ofthe verb might refer either to the agent or the instrument.But the semantics of HOLD indicate that these roles mustbe filled by objects of mutually disjoint classes of objects.Utilization of this knowledge allows a system to assignthe role of agent to THE MAN, but assign the role of in-strument to THE WRENCH.

Discourse knowledge concerns the way clues from thecurrent context are used to help interpret a sentence. Forexample, if we have just been talking about this month'sissue of BYTE, the noun phrase "the magazine" in:

I'VE ALREADY READ MY COPY OF THEMAGAZINE.

is easily understood in this context as referring to thismonth's issue of BYTE. Yet, we often have personalknowledge of hundreds of issues of various magazines.

340 September 1981 © BYTE Publications Inc

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BYTE September 1981 341

DB ACCESS PRONOUNS ELLIPSIS

ENHANCEMENT

BY

DECOMPOSITION

CAPABILITY

RESOLUTION

OF DEFINITELY-DETERMINED

NOUN PHRASES

IN CONTEXT

NONLITERALINTERPRETATION

Figure 11: A graph of capability versus cost for systems that can handle natural-language queries.

The ability to pick the one of current interest is based onspecific knowledge of the current situation.

World knowledge is concerned with information abouthow the world is currently configured and about physicalconstraints upon possible configurations. For example,we understand:

PRESIDENT REAGAN FLEW TO CALIFORNIA.

to mean that he was flown to California as a passenger inan airplane. Had the sentence been about a bird, wemight have taken the sentence to mean that the bird didthe flying.

As an example of how knowledge about the currentphysical situation can be of aid in understandingsentences, consider again the sentence:

PUT THE HAMMER IN THE TOOLBOX ON THETABLE.

discussed in the earlier paragraph on syntax. If we knowthat the hammer is currently in a toolbox on the floor, theonly interpretation of the sentence is to lift the hammerout of the toolbox and place it onto the table. The otherinterpretations are ruled out because they are impossiblein the current state of the world.

Knowledge of mental states relates to comprehendingthe knowledge and goals of other participants in adialogue. The use of such knowledge is shown in thelocked-toolbox example in listing 7.

Cost as a Function of Capability

The preceding sections sketched a spectrum of natural-language processing capabilities—ranging from isolated

questions about the data in conventional data bases,through the literal interpretation of utterances indynamic contexts, to an understanding of the underlyinggoals and mental states of participants in a dialogue. Aswould be expected, progression through this spectrumentails rapidly escalating costs in two areas: the researchand programming effort required to reach a particularlevel of capability, and the computing resources(measured in the number of machine instructions thatmust be executed and the memory requirements) neededto function at a given level.

This situation is illustrated graphically in figure 11,which plots cost as a function of system capability.Although the diagram shows a sharp rise in cost with in-creased capability, the situation is probably even moredramatic than indicated, and the cost scale might best beinterpreted as being logarithmic.

The capability dimension has been separated into threemajor regions by two dividing lines. It appears thatcapabilities beyond (to the right of) the leftmost line re-quire systems with explicit models of concrete objects inthe world, the relationships among them, and the typesof processes that can alter those relationships. The moreadvanced capabilities beyond the rightmost line requirefurther enhancements for modeling such things as themental states of dialogue participants.

Figure 12 repeats the curve of figure 11, but also showscurves for developing three kinds of systems. Systems oncurve A are built without the use of explicit models. Theycover most of the principal linguistic phenomena neededfor accessing conventional data bases and, up to the pointat which curve A intersects curve B, can be constructedand operated more economically than other types ofsystems. As the need for world models increases, at-

342 September 1981 © BYTE Publications Inc

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BYTE September 1981 343

DB ACCESS PRONOUNS ELLIPSIS

ENHANCEMENT

BY

DECOMPOSITION

CAPABILITY

RESOLUTION

OF DEFINITELY-DETERMINED

NOUN PHRASES

IN CONTEXT

NONLITERALINTERPRETATION

Figure 12: A graph of capability versus cost for different kinds of natural-language systems. Curve A refers to systems that do not useexplicit world models. Curve B refers to systems that do use explicit world models. Curve C refers to systems that are built on aknowledge base including information about the goals and beliefs of other intelligent entities.

tempts to circumvent the problem by using various adhoc methods become prohibitively expensive or down-right impossible.

Systems on curve B are built with explicit worldmodels that lack the ability to deal with intensional con-cepts, such as the goals and beliefs of others. Althoughthese systems have greater capability potential than thoseon curve A, they entail considerable initial costs in theconstruction of machinery to support and exploit themodels.

(Intensional concepts take into account the meaning,rather than just the truth values, of logical sentences. Instandard logic, the truth value of a complex formuladepends only on the truth of its subexpressions (eg: thetruth of (P OR Q) depends only on the truth of P and thetruth of Q; no other properties of P and Q matter). Theoperator BELIEVE, however, is intensional because thetruth of "A believes that P" depends on the meaning of P,not just its truth value. The problem is that many of therules of standard logic, such as substitution of equals forequals, do not apply when intensional operators are in-volved. To use a classic example, since "the morningstar" and "the evening star" refer to the same object, itmust be the case that "the morning star is Venus" is trueif, and only if, "the evening star is Venus" is true.However, it might be that "John believes the morning staris Venus" is true, but that "John believes the evening staris Venus" is false because, although the two embeddedsentences possess the same truth value, they differ inmeaning.)

Systems on curve C, if any existed, would be builtupon a knowledge base supporting many intensional con-cepts. The initial costs of creating computational

machinery to support this level of sophistication appearto be quite high.

In today's computing environment, and in light of thecurrent state of the art in natural-language processing,the only systems that perform robustly and efficiently aresystems of type A. As mentioned in an earlier section onLADDER-like systems, there are a number of systems ofthis type, including one (INTELLECT, described inreference 10) available now as a commercial product.

A number of experimental systems of type B have beenbuilt, including SHRDLU, SAM, and TDUS. But thesesystems are currently of little practical value because theyare relatively slow and use models that, while consumingconsiderable memory, cover pieces of the world too smallto be of much more than academic interest.

Computational linguists and workers in related fieldsare devoting considerable attention to the problems oftype-C systems. But currently, only bits and pieces ofcomponents for such systems are being constructed. Forexample, Moore (in reference 17) and Appelt (in reference1) have devised formal methods for reasoning about theknowledge of others, and Perrault, Allen, and Cohen (inreferences 6 and 18) have devised systems that actuallyplan speech acts. But there is a huge gulf between the firstexperiments that demonstrate the feasibility of a principleand the creation of useful systems based on that princi-ple. Our current state of understanding in natural-language processing is similar to that of the ancientmakers of Chinese fireworks as compared with modernspace research. In terms of achieving fluency in the field,our current experiments are merely fireworks poking afew holes in the darkness.

Nevertheless, even though the fluent use of natural

344 September 1981 © BYTE Publications Inc

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language by machines may still be years away, it is im-portant to realize that many practical applications ofnatural-language processing can be supported by systemsof types A or B, both of which can be built now.Although the computational costs for natural-languageprocessing will always be relatively high when comparedwith machine languages, the introduction of VLSI (verylarge-scale integration) technology promises to ease theattendant cost. Processes that were once performed onlyin the laboratory on research computers costing over onemillion dollars are becoming practical on personal com-puters. As a general trend, the expense of programmingcontinues to rise while computer hardware continues todrop in price. For some applications, we may havealready reached the point where it is cheaper to createsystems that use subsets of English than it is to train peo-ple to use formal languages.

Current Capabilities of Type-A Systems

To reach a better understanding of the types of natural-language processing possible on a cost-effective basis us-ing technology available today, consider the dialogue oflisting 8, which shows some of the more advanced typesof processing available in the LADDER system.

Interaction 1 shows how LADDER deals with sentencesit cannot understand. After trying to interpret the inputas first a complete and then an elliptic sentence, LADDER

prints an error message indicating that the word "NY" isnot known to it. The system also indicates that to com-plete the partial input, "How far is the Kennedy from theport of," it needs a construction matching its internalconcept of a < PORT > . In interaction 2, the user seeksinformation about what LADDER would accept as avalid expression for a < PORT >. This is a very in-teresting question because it is not about the data in thedata base, but rather a question about the language-processing system itself. LADDER can process questionsabout a variety of knowledge sources, including specialroutines that inspect its own internal information aboutthe linguistic constructions it can accept. Using one ofthese special routines, LADDER produces a list of possi-ble expressions for <PORT>, including the expressionNEW YORK, which the user identifies as being what ismeant by NY.

At this point, the user could rephrase the question byusing NEW YORK in place of NY. But it is important fornatural-language processing systems to accommodate thelinguistic constructions their users are comfortablewith—to accept inputs in the users' own terms, ratherthan force the users to master the system's terms. In par-ticular, the learning of synonyms is relatively inexpensivecomputationally and quite helpful to users. In interaction3, the user types a statement in English to tell LADDERthat NY is a synonym for NEW YORK. Then, in interac-tion 4, the user asks that interaction 2 be tried again. This

346 September 1981 © BYTE Publications Inc

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Listing 8:

system.

Another actual conversation with the LADDER

I —How far is the kennedy from the port of NY?Trying Ellipsis: ELLIPSIS HAS FAILED

The parser does not expect the word "NY" to follow "HOW FAR ISTHE KENNEDY FROM THE PORT OF"Options for next word of symbol are: <PORT>2—What is a <PORT>?PARSED!

"<PORT>" may be any sequence of words following one of the pat-terns:

<PORT> => CAPETOWN= > NEW YORK= > NEW ORLEANS[etc.]3—Define NY like New York.PARSED!NY

4—redo 2

[i.e., How far is the Kennedy from the port of NY?]PARSED!(GCDIST 1974)5—Ql Kennedy[System gives syntax error.]6—Let "Ql kennedy" be a paraphrase of "what is the position, fuel

status and homeport of the Kennedy"PARSED!

<S> => Ql <SHIP>7—ql kennedyPARSED!

(POSITION 4000N0600E PCFUEL 90 PORT MAYPORT)8—American subs in the North Atlantic

Trying Ellipsis: Ql AMERICAN SUBS IN THE NORTH ATLANTICSHIP POSITION PCFUEL PORT

STURGEON 3700N7600W 100 NORFOLK

WHALE 3750N7700W 100 NORFOLK

ASPRO 3000N3000W 100 NORFOLK

[etc.]9—Let "show the forcestatus of the Kitty Hawk" be like "Display the

employment and readiness condition of the Kitty Hawk. Print her

destination. List ships in her organization."PARSED!

[New production added to system.]10—show the forcestatus of KennedyPARSED![questions defined in 9 for Kitty Hawk are answered for the Kennedy.]

II —Define "Kennedy no nagasa wa ikura desuka" like "what is the

length of the kennedy."PARSED!

[Production added to system.]12—Fox no nagasa wa ikura desuka?PARSED!LEN = 547

time, using the newly defined synonym, LADDER suc-cessfully interprets the question and produces the answerthat the great-circle distance (labeled as GCDIST) fromthe Kennedy to New York is 1974 miles.

It is worth noting that LADDER must do more toanswer queries 2 and 4 than merely retrieve informationfrom a data base. Only the positions of ports and shipsare stored in the data base—not the distances betweenthem. Thus, LADDER interfaces not only with the database, but also with programs that make calculationsbased on data-base information. Some of these are nottrivial. For example, to find how long it would take a ship

348 September 1981 © BYTE Publications Inc

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Microstat is an advanced statistics package designed lor use in research,education and industry. Microstat is a file-oriented statistics package with aData Management Subsystem (DMS) that creates the data files plus theability to: edit, list, destroy, delete cases, augment, sort, rank-order, lag,move, merge and transform the data. The data transforms include: add,subtract, multiply, divide, reciprocal, log, natural log and antilog, exponen-tial, linear transformations plus adding any number of variables to createnew variables.

Once the file is created, it can be used to produce: Descriptive statistics,Hypothesis tests (mean and proportion), AN OVA (one-way, two-way andrandom blocks), Scatterplots, Frequency distributions. Correlation analysis,Simple and Multiple regression, Time Series, Nonparametric tests (11 ofthem), Crosstabs and Chi-square, Factorials, Permutations. Combinations,and 8 Probability distributions.

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If you use the CP/M™ operating system, life just got a whole lot easier foryou. Interchange is a Z-80™ assembly language program that gives you allof the features that PIP doesn't, plus several unique features. Some of thefeatures of Interchange include:

DIR, in the usual fashion, plus listing all files excluding those with a specifiedcharacter. Read/write status is also given.

ERA, as usual plus exclusive erases. In addition, a "Q" switch can be used toquery on each erase, a "W" allows erases of R/0 files without query(normally you are queried), and an "R" switch if system files are to beincluded.

LIST permits printer listings with formatting controlled by TAB, WIDTH,LINES and WRAP. If you are using the QT Systems Clock Board, listingsinclude the date and time.

COPY including exclusive copies and the optional "Q", "W" and "R"switches plus an "E" switch that queries if the file already exists. It alsoallows for changing disks in the middle of a copy if either the disk ordirectory become full. It automatically verifies copies.

STAT, with ambiguous, unambiguous and exclusive listings. It produces analphabetized listing and includes each file length, total directory entries andspace used and unused.

Other commands include RENAME (including ambiguous), HELP, START,END, CLEAR. RESET, DATE, TIME. TAB. WIDTH. LINES. WRAP. QT.SETIT and TYPE. Once you've used Interchange, we doubt that you'll everuse PIP again. The price of Interchange is $59.95 and the manual isavailable for $10.00. Orders must be accompanied with your CP/M serialnumber. Interchange is recommended for a 32K or larger system and willnot run with an 8080 CPU. At the present time, only User 0 is supported.

CBesic2 is a registered trademark of Compiler Systems.CP/M is a registered trademark of Digital Research.

Circle 131 on inquiry card.

BYTE September 1981 349

to reach a given location, LADDER cannot simply dividethe great-circle distance by the cruising speed of the ship,because the shortest path between two points on earthoften crosses land masses. So LADDER computes routesthat avoid land masses, which requires a knowledge ofworld geography.

Interactions 4 through 8 illustrate LADDER'S ability tolearn new syntactic constructions, as well as synonyms.Suppose a user has certain questions to ask repeatedlyabout different ships. Natural language is ideal for one-time questions, but a shorthand version would be usefulfor those used repeatedly. If, as in interaction 5, the userasks a shorthand question such as "Ql Kennedy?", a syn-tax error will occur. However, the user can easily tellLADDER, by giving an example in English, how a newshorthand is to be interpreted. This is done in interaction6. In response to this request, LADDER creates a newproduction rule that matches inputs that start with "Ql"and end with any expression designating a < SHIP >.

In interaction 7, this newly defined construction is usedto ask for information about the Kennedy. In interaction8, to obtain the same information for all the Americansubs in the North Atlantic, just "American subs in theNorth Atlantic" need be typed. LADDER'S elliptical-processing routine, operating on the newly defined con-struction just as on the standard ones, fills in the rest.Because there are multiple answers to the question, atable is produced to display the data retrieved.

In interaction 9, the user tells LADDER to make a cer-tain input sequence equivalent to not just one but a wholeseries of questions. It is as if the user were writing smallprograms in English, using English pronouns for formalparameters. In interaction 10, the new construction isused, but with a different ship than the one used to definethe construction.

As an extreme example of this ability to accommodatethe user-defined constructions, in interaction 11, the usertells LADDER a Japanese paraphrase of the English ques-tion, "What is the length of the Kennedy?" In interaction12, the user poses this question about the Fox, rather thanthe Kennedy, entirely in Japanese.

The language-processing capabilities demonstrated inlistings 3 and 8, while far from those possessed by a fluent

user of natural language, seem quite adequate for a widerange of practical applications. This technology, usingthe language INTERLISP, is available today in a largecomputing environment. It requires approximately 500milliseconds to process a query—far less than the timeneeded to retrieve information from a large data base.With proven algorithms and data structures in hand, it isnow essentially an engineering task to implement thistechnology on smaller machines in widely available pro-gramming languages. Such engineering will require aconsiderable effort, but the path of development appearsto be clear of major theoretical obstacles.

One of the practical problems currently limiting the useof natural-language processing systems for accessing databases is the lack of trained people and good support toolsfor creating the knowledge structures needed for eachnew data base. In laboratory systems, researchers havemanually compiled bodies of knowledge such as informa-tion about the vocabulary employed in a particular ap-plication or about the logical structure of particular databases. Work has already begun on new methodologies toautomate this task or even make it entirely unnecessary(see references 9, 15, and 25).

Conclusion

Considerably more research in computationallinguistics will be required before mechanical devices canbe created that are fluent in the use of natural language.However, current research efforts are shedding new lighton the types of knowledge required for communication inhuman languages, as well as on prospective mechanismsfor encoding and applying that knowledge in computers.These efforts are showing that language use is not anisolated intellectual activity; it also involves our basicfacilities for commonsense reasoning and planning. Acomputer system fluent in a natural language will be agenuinely intelligent machine.

Although the fluent use of natural language bymachines remains a long-term goal, a number of practicalmechanisms have been developed to deal with significantfragments of language in specialized application areas.For many applications, an ability to communicate withinsuch fragments is both sufficient for the task at hand and

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BYTE September 1981 351

How to Get More Information About Natural-Language Processing

The Association for Computational Linguistics is a profes-sional society for people interested in this subject; itpublishes the American Journal of ComputationalLinguistics. For information, contact Donald Walker, SRI In-ternational, Menlo Park CA 94025. Readers are also referredto the American Association for Artificial Intelligence (con-tact Bruce Buchanan, Computer Science Department, Stan-ford University, Stanford CA 94305), and the CognitiveScience Society, which publishes the journal CognitiveScience (contact Donald Norman, Center for Human Infor-mation Processing, C-009, University of California at SanDiego, La folia CA 92093).

clearly preferable to forcing users to learn machine-oriented languages. In coming years, we expect to seenatural-language processing employed in an increasingnumber of practical applications, enabling more andmore people to interact directly and effectively with com-puter systems. ■

Acknowledgments

We wish to express our thanks to SRI International and Machine In-telligence Corporation for supporting the preparation of this article,and acknowledge the helpful critiques of early drafts that were providedby Barbara Grosz, Norman Haas, Robert Moore, lane Robinson, andDonald Walker. Listing 5 and figures 3 through 5 were adapted fromUnderstanding Natural Language by Terry Winograd (Academic Press,1972) with permission of the publisher and author.

References

1. Appelt, D E. "A Planner for Reasoning about Knowledge and Ac-tion." Proceedings of the First Annual National Conference on Ar-tificial Intelligence, August 1980, pages 235 through 239.

2. Biermann, A B. "Approaches to Automatic Programming." Ad-vances in Computers, volume 15, 1976, pages 1 through 63.

3. Bruce, B. "Pragmatics in Speech Understanding." AdvancePapers of the Fourth International Joint Conference on ArtificialIntelligence, 1975, pages 461 through 467.

4. Burton, R R. "Semantic Grammar: An Engineering Technique forConstructing Natural Language Understanding Systems." BBNReport 3453, Bolt, Beranek, and Newman Inc, Cambridge MA,December 1976.

5. Carbonell, J. "Politics." Inside Computer Understanding(reference 23), pages 259 through 317.

6. Cohen, P R and C R Perrault. "Elements of a Plan Based Theory ofSpeech Acts." Cognitive Science, volume 3, number 3, 1979,pages 177 through 212.

7. Grosz, B J. "Utterance and Objective: Issues in Natural LanguageCommunication." Sixth International Joint Conference on Ar-tificial Intelligence, 1979, pages 1067 through 1076; also in AlMagazine, volume 1, number 1, 1980, pages 11 through 20.

8. Grosz, B J. "Focusing and Description in Natural LanguageDialogues." Elements of Discourse Understanding: Proceedingsof a Workshop on Computational Aspects of Linguistic Structureand Discourse Setting, A K Joshi, I A Sag, and B L Webber(editors), Cambridge: Cambridge University Press, 1981.

9. Haas, N and G G Hendrix. "An Approach to Acquiring and Apply-ing Knowledge." Proceedings of the First Annual National Con-ference on Artificial Intelligence, August 1980, pages 235 through239.

10. Harris, L R. "User Oriented Data Base Query with the ROBOTNatural Language Query System." Proceedings of the Third Inter-national Conference on Very Large Data Bases, October 1977.

11. Hendrix, G G. "The LIFER Manual: A Guide to Building PracticalNatural Language Interfaces." Al Center Technical Note 138, SRIInternational, Menlo Park CA, February 1977.

12. Hendrix, G G, E D Sacerdoti, D Sagalowicz, and J Slocum."Developing a Natural Language Interface to Complex Data."Association for Computing Machinery Transactions on DatabaseSystems, volume 3, number 2, June 1978.

13.Hobbs, J R and D A Evans. "Conversation as Planned Behavior."Al Center Technical Note 203, SRI International, Menlo Park CA,1979.

14. Kaplan, S J. "Cooperative Responses from a Portable NaturalLanguage Data Base Query System." PhD Dissertation, Universi-ty of Pennsylvania, Philadelphia, 1979.

15. Lewis, W H. "TED: A Transportable English Datamanager." Pro-ceedings of the Principal Investigators' Meeting of the ACCATProgram, October 1979.

16. Mann, W. "Toward a Speech Act Theory for Natural LanguageProcessing." ISI/RR-79-75, USC/lnformation Sciences Institute,Marina del Rey CA, 1980.

17. Moore, RC. "Reasoning About Knowledge and Action." Al CenterTechnical Note 191, SRI International, Menlo Park CA, October1980.

18. Perrault, C R and J F Allen. "A Plan-Based Analysis of IndirectSpeech Acts." American Journal of Computational Linguistics,volume 6, number 3-4, July-December 1980, pages 167 through182.

19. Robinson, A E, et al. "Interpreting Natural-Language Utterancesin Dialog About Tasks." Al Center Technical Note 210, SRI Inter-national, Menlo Park CA, 1980.

20. Robinson, J J. "DIAGRAM: A Grammar for Dialogues." Al CenterTechnical Note 205, SRI International, Menlo Park CA, February1980.

21. Sacerdoti, E D. A Structure for Plans and Behavior. New York:Elsevier North-Holland, 1977.

22.Schank, R and R Abelson. Scripts, Plans, Goals, and Understand-ing. Hillsdale NJ: Lawrence Erlbaum, 1977.

23.Schank, R and C Riesbeck. Inside Computer Understanding.Hillsdale NJ: Lawrence Erlbaum, 1981.

24.Templeton, M. "EUFID: A Friendly and Flexible Frontend for DataManagement Systems." Proceedings of the 1979 National Con-ference of the Association for Computational Linguistics, August1979.

25.Thompson, F B and B H Thompson. "Practical Natural LanguageProcessing: The REL System as Prototype." Advances in Com-puters 13, M Rubinoff and M C Yovits (editors), New York:Academic Press, 1975.

26. Waltz, D. "Natural Language Access to a Large Data Base: AnEngineering Approach." Proceedings of the Fourth InternationalJoint Conference on Artificial Intelligence, September 1975,pages 868 through 872.

27.Wilensky, R. "Meta-Planning." Proceedings of the First AnnualNational Conference on Artificial Intelligence, 1980, pages 334through 336.

28.Wilks, Y. "Natural Language Understanding Systems within the AlParadigm: A Survey and Some Comparisons." Linguistic Struc-tures Processing, A Zamplolli (editor), Amsterdam: North-Holland,1977, pages 341 through 398.

29.Winograd, T. Understanding Natural Language. New York:Academic Press, 1972.

30. Woods, W A. "Transition Network Grammars for NaturalLanguage Analysis." Communications of the Association forComputing Machinery, volume 13, number 10, October 1970,pages 591 through 606.

31.Woods, W A, R M Kaplan, and B Nash-Webber. "The LunarSciences Natural Language Information System." BBN Report2378, Bolt, Beranek, and Newman Inc, Cambridge MA, 1972.

352 September 1981 © BYTE Publications Inc

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BYTELINES

News and Speculation About Personal Computing

Conducted by Sol Llbes

I eerlng Into RadioShack's Crystal Ball: Tan-dy Corporation (RadioShack's parent firm) oncekept a very tight lid on up-coming products. But nowit's leaking information onproduct plans, some ofwhich extend well into 1982.

Here's what to expect:Among its most ambitiousprograms, Tandy plans todouble its hardware andsoftware products within thenext six months —judging bypast performance, it can doit. Several new peripheralhardware products will beadded to all of its currentmachines, from the pocketcomputer to the Model IIbusiness-oriented system.The Model II will be offeredwith an optional 10-mega-byte hard-disk system thatwill include a 15 k bpi (bitsper inch) tape backup. Thecomplete hard-disk systemwill cost less than $5000.Also in the works is a multi-processing and -program-ming system that will allowup to sixteen Model Ms to bechained together. A newsystem (Model IV?) with ca-pabilities somewhere be-tween the Models II and III,but closer to the Model II,will be unveiled. It will in-clude 8-inch floppy-diskdrives and a better disk-oper-ating system, but it won't beCP/M compatible. Expect itsbase price to be in the $1500to $1800 neighborhood.

As for software:

• Radio Shack will in-troduce packages gearedtoward specific "vertical"markets (eg: medical, legal,educational, etc).

• There will be a softwarepackage that allows theModel II to read and write

IBM-format disks and toserve as a terminal on anIBM system.

• There will be upgradedversions of TRSDOS for theModels I, III, and II.

Most of the upcomingModel III software willadhere to the company'spolicy of maintaining com-patibility with the olderModel I system. I must giveRadio Shack credit for notmaking the mistake made bymost other computer com-panies who virtually disowntheir older model computerswhen a new system isbrought out, forcing cus-tomers to "junk" the oldersystem and buy a new sys-tem merely to run new soft-ware.

Tandy also plans tochange the name of itsRadio Shack ComputerCenters to Office ProductCenters. These centers willsell copiers, facsimilemachines, and other officeproducts, as well as com-puter systems.

dllog's New FallFashion: This fall Zilog willintroduce an enhanced Z80called the Z800. The desig-nation doesn't mean that theZ800 is ten times better thanthe Z80 and only one-tenthas powerful as the Z8000,but Zilog claims it will havethree times the performanceof the Z80.

Zilog says that the Z800will be fully compatible withthe Z80 instruction set,which is a wise decisionbecause the old softwarecan still be used. It will con-tain circuits that facilitatemultiplication, division, andmemory mapping to accessup to 4 megabytes of mem-ory. It will be offered in a

nonmultiplexed version, likethe Z80, and a Z-bus-com-patible version that can beused as a Z8000 peripheral.Zilog hopes to start shippingsamples soon.

Vommodore ReleasesThe 6508 Microproces-sor: After years of talkabout an upgraded versionof the 6502 microprocessor(used in the Apple II, Com-modore PET, Atari 400 and800, etc), Commodore Semi-conductor, Norristown,Pennsylvania, has finallydone it: the 6508. The 6508has 256 bytes of program-mable memory and an 8-bitparallel port. Its instructionset is compatible with the6502's and its clock rate re-mains at 2 MHz. Com-modore has let it be knownthat several other versions ofthe 6502 are forthcoming.They will include timer/counters, serial ports, andother functions. Its clockrate could go as high as6 MHz.

I

s There A MicrofloppyDisk In Your Future?

Sony is currently providingOEMs (original equipmentmanufacturers) with samplesof its new 31/2-inch "micro-floppy"-disk drives. Thedrive represents a newtechnology that departsfrom the traditional 5- and8-inch drives. Sony packs437.5 K bytes per side into adrive that's 27% smallerthan standard 5-inch models.Five-inch drives typicallystore about 250 K bytes(double-density) or 125 Kbytes (single-density).

Even though the 31/2-inchdrive's compactness is veryattractive for portable com-puters and word-processing

systems, Sony is meetingsome resistance from OEMswho are leary of purchasingan unproven product from asingle source.

The microfloppy has astiffer media and a rigid en-velope with a shutter overthe head-access slot to pro-tect the disk. The result isless contamination and bet-ter media stability, which, inturn, allows greater ac-curacy and higher data den-sity. Sony has also borrowedfrom its video-head technol-ogy in developing the read/write head for this drive.

Sample drives range inprice from $400 to $500, notincluding a controller inter-face, although many of thecurrently available con-trollers can be used with lit-tle or no modifications. Theprice should drop to $200 to$300, in 500-unit quantities.

Sony plans to use thedrives in its new word-pro-cessing systems, which willbe introduced later this year.A 1-megabyte version of thedevice is expected early nextyear, and Sony will probablyuse it in its Series 35 small-business systems. There arerumors that Sony is develop-ing a 3Vi-inch hard-diskdrive.

Shugart and several otherfloppy-disk suppliers aretaking a hard look at "micro-floppies." There is no doubtthat the trend is to smallerdisk-storage units. The ques-tion really is whether or notmanufacturers will adoptthe Sony format or create anew standard ... or willsomething different emerge?

I he IAPX432 PictureBecomes Less Fuzzy: Re-cently, EDN magazine com-mented on where the indus-try can be expected to go

354 September 1981 © BYTE Publications lnc

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BYTE September 1981 355

BYTBLINES.

with the new Intel 32-bitmicroprocessor. I havetaken the liberty of extract-ing some of the major com-ments here.

The iAPX432 was designedby and for computer scien-tists, rather than electricalengineers (as were Intel's 4-,8-, and 16-bit microproces-sors). The iAPX432's internalelements are less accessiblethan those in other micro-processors, so writing pro-grams will be different.

"Instead of consideringthe machine in terms of bitsand registers, you must fo-cus on software objects . . .the 432 has no assembly lan-guage, per se; you mightconsider its instruction set tobe a high-level language . . .a nearly optimum intermedi-ate language specifically de-signed to simplify the task ofwriting efficient compilers.In turn, these compilers caneffectively handle progamscoded in high-level lan-guages." The iAPX432's in-struction set "does not con-stitute a complete operatingsystem; rather, it containsthe essential primitives fromwhich you can constructsuch an operating system . . .the machine can't be pro-grammed directly in codewritten in, say, Ada or FOR-TRAN; you need the appro-priate compiler. Because the432 simplifies system pro-gramming, programmersneed not be hardware ex-perts; thus personnel with alower level of expertise canprogram it. Further, pro-grams written in high-levellanguages can generally bedeveloped more rapidlythan those coded in assem-bly language.

"The machine performsarithmetic operations quick-ly and with a high level ofprecision. It also automati-cally prevents many typicalprogramming errors (youcan't inadvertently executedata, for example). Further,

it provides functional redun-dancy checking, a featurethat allows graceful systemdegradation when a CPU[processor] fails in a multi-processing environment.And finally, the 432 ensuresthat all programs are natur-ally reentrant and recursive.The 432 chip set is complexand currently very expen-sive. It could incur speedpenalties when performingcertain operations."

The iAPX432 will not bethe ultimate processor. "Al-though its instruction set isclose to the ideal," saysEDN, "it might be improvedin other ways." It will notmake 4-, 8-, and 16-bit micro-processors obsolete; and, infact, it should increase themarket for these as 'peri-pheral processors.'

"In summary, a good anal-ogy is that the 432 is to stan-dard microprocessors whatthe 7400 Series TTL was todiscrete-device logic gatesand flip-flops. It should freeEEs [engineers] from manymundane "system-designchores, allowing them toconcentrate on more re-warding creative pursuits,while also reducing theirprojects' software costs. It'sa minicomputer replace-ment, one that will open upscores of application oppor-tunities."

Intel is already shipping aboard-level iAPX432 eval-uation system, called the In-tellec 432/100. It consists ofa board with a completeiAPX432 processor, RS-232Cserial interface, evaluationsoftware, and seven volumesof documentation. The usercan plug the board into anIntel Intellec developmentsystem and create and ex-ecute iAPX432 programs us-ing an object-oriented lan-guage. The 432/100 costs$4250.

The Intellec uses the IntelMultibus (IEEE-796), whichhas a 16-bit-wide data bus.

The 32-bit-wide processor isinterfaced to the bus via aninterface-processor that han-dles data-bus transfers astwo 16-bit words (the IBM360, which was also a 32-bitprocessor, handled datatransfers as 8-bit words, onits smaller machines).

Several S-100 (IEEE-696)bus-system manufacturershave iAPX432 developmentprojects underway. I expectto see an S-100-basediAPX432 machine with diskoperating system later thisyear.

I he Software Shop:

When I was a kid, I would goto the record shop and buy acopy of one of the top-tenrecords on the hit-parade.Well, soon I may be going tothe "software shop" to buy acopy of one of the top-tenprograms. At least that iswhat Cut & Curl hopes. Itplans to open a franchisedchain of stores that sell onlysoftware —"software super-markets." Cut & Curl alreadyfranchises 500 Edie AdamsCut & Curl and Great Expec-tations Precision Haircuttingsalons. The first ProgramsUnlimited store has beenopened, and Cut & Curl istalking about 100 morestores.

R

i andom News Bits:

Apple Computer Inc re-ported that sales for the firstquarter of 1981 tripled overthe same period a year ago.Sales were nearly $79million, with a net of $9.2million —a 16% increaseover the previous quarter.Also, Apple claims to haveproduced over 200,000 Ap-ple lis and that the AppleIll's "production problems"have been ironed out (mostof the original design grouphas been fired). The AppleIII is now in full production.. . . Zilog reported an $11million loss on $42 million

business for 1980. Zilog hasyet to show a profit. . ..Commodore expects to in-troduce its "Micromain-frame," with 132 K bytes ofmemory and 6502 and 6809processors. It is really a PETcomputer with a second pro-cessor (the 6809). You canelect to run either the 6502or the 6809. Commodoreclaims to have BASIC, FOR-TRAN, APL, Pascal, and anAssembler ready for the ma-chine. COBOL will comelater. The software was de-veloped at the University ofWaterloo in Ontario,Canada. Commodore hasnot yet set the price. ... In-terlude, Houston, Texas,claims to have sold 15,000copies of its sex-orientedsoftware package for the Ap-ple 11 and TRS-80 computers.The program asks usersquestions about themselvesand their partners, and thentells them how to enjoy theirspare time. . . . Florida DataCorporation, Melbourne,Florida, has introduced twoserial dot-matrix printersthat can rocket along at 600cps (characters per second)for draft or data-processingoutput and at 150 cps for let-ter-quality output —that'sthree times faster than anydaisy-wheel printer. The let-ter-quality output is pro-duced by passing the headover each line four times,with the dots displacedslightly on each pass to fillin the character. . . . Intelwill introduce a set of twointegrated circuits for theEthernet controller and in-terface that will allow a userto implement the physicaland data links. A little bit ofextra circuitry, some specialcables, and interfacing soft-ware, and you can connectany personal computer to anEthernet system. . . .

I exas Instruments'Bubble Bursts: In a sur-prise move, Texas Instru-

356 September 1981 © BYTE Publications Inc

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•With our normal fust shipping, wc have time to test; expedited shipment mavprcehidc testing."A-El. does not wish to Imply that any of these fine organizations endorse A.E.I..merely that A.E.I. Is proud itt have them as customers.

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BYTE September 1981 357

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ments (Tl) will phase out itsmagnetic bubble-memoryproducts as part of a com-pany-wide retrenchmentprogram. The move, ironical-ly, comes less than a monthafter Tl announced it was ex-panding its line. Rockwell In-ternational announced asimilar move earlier thisyear. Besides dropping itsbubble-memory line, Tl alsoannounced plans to get outof the digital-watch businessand lay off 3% of its workforce.

I he 64 K-BIt MemoryDevices Are On TheWay: Intel and a few otherintegrated-circuit makers arenow shipping 64 K-bitmemories. Prices are cur-rently in the $30 range butare expected to drop toaround $8 by year's end.Look for products usingthese circuits by early nextyear. It's rumored that Applehas placed an order for60,000 of the devices, at $12a chip, for a new businesscomputer.

Reportedly, Intel has256 K-bit memory devices inthe prototype stage. Usingthe 64 K-bit devices, youcould build a 64 K-bytememory system using onlyeight memory circuits. Whenthe 256 K-bit products be-come available, only two cir-cuits will be required.

MAIL: I receive a largenumber of letters eachmonth as a result of thiscolumn. If you write to meand wish a response, pleaseinclude a self-addressed,stamped envelope.

Sol LlbesPOB 1192Mountainside NJ 07081

358 September 1981 © BYTE Publications Inc

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BYTE September 1981 359

Ask BYTE

Conducted by Steve Ciarcia

Clarcla'sCircuit Court?

Dear Steve,

I am a member of theEvanston Township HighSchool Computer Club, and Iwas wondering if you couldsettle a dispute for me. Thesupervisor of our computerroom will not allow us todouble-side our floppy disksbecause of the fact that theyaccelerate the accumulationof oxide and dust deposits onthe read/write head of thedisk drive. Is this true7Scott ColemanEvanston II

/ don't like to jump into themiddle of disputes, but if youcan live with my opinion, Iwill voice it. It should notmake any difference whetheryou have a single-sided ordouble-sided disk. The disk-drive head does not come incontact with the oxide sur-face: it rides above it. So,theoretically, it should notcause any accumulation onthe read/write head.

Now, that's in theory. Intruth, there's always someoxide that comes off on thehead, but if the computerroom is doing regular main-tenance, which is to clean theheads every once in a while,it should never be built up toa point at which it makes anydifference anyway.

Perhaps the way to settlethis is to have the computerclub volunteer to clean thedisk drives once in a while.. . . Steve

Tools of the Course

Dear Steve,

I am beginning implemen-tation of a hands-on micro-computer experimentationand interfacing course here atthe University of Dubuque

Theological Seminary. I wantto establish a digital-micro-processor laboratory. Whatwould you consider to be theminimum test equipment nec-essary? Our financial re-sources are somewhat limit-ed, so your advice would bemost helpful.Terry A WardDubuque IA

At the very minimum, Iwould recommend that youget an oscilloscope. If youcan afford it, it should bedual-trace and have at least a15 MHz bandwidth. With it,you can troubleshoot manypieces of equipment and per-form some logic-analyzerfunctions. If you can affordit, of course, a logic analyzeris always a good piece ofequipment to have around.However, you can spend somuch time teaching peoplehow to use a logic analyzerthat you don't have any timeleft in the course.

Other than an oscilloscope,the only other piece of equip-ment that you probably needwould be a simple digitalvoltmeter (DVM) or digitalmultimeter.

Often the things that areneeded when teaching stu-dents are not the things thatyou can buy off the shelf astest equipment. Frequently,simpler equipment, such as abuffered LED (light-emittingdiode) that functions as alogic probe, is what'snecessary.

A logic probe, 'scope, anda DVM should take care ofpractically anything thatwould arise. . . . Steve

Auto Warning

Dear Steve,

In a book on microcom-puters that I read, the authorpredicted that an automotive

warning device that wouldtell drivers they were tooclose to another vehiclewould be devised.

It occurred to me that sucha gadget might be realizedright now using the Polaroiddevelopment kit and a simplesingle-board computer. Soft-ware, it seems to me, mightbe the biggest hurdle. Whatdo you think?Bob CraftsEdgartown MA

The Polaroid ranging sen-sor is definitely usable for adriver-warning device likethe kind you mentioned.However, I don't see this sen-sor being used as a crash-avoidance device because itsresponse time is a little slow. 1have seen one company usingthe device on each side of acar's fenders, with a dash-mounted display for thedriver. In my mind, whilethis may work, its feasibilityand production is anothermatter. It would seem to berather expensive unless pro-duced in large quantities.

When using the Polaroiddevelopment kit in an auto-mobile, you must try to iso-late the ignition noise fromany power being drawn fromthe car's electrical system.From my experience, thePolaroid ranging kit is alsoelectromagnetic interferenceand static sensitive. If used ina car, it should be in a shield-ed enclosure. . . . Steve

Scheming Schematics

Dear Steve,

I would like to expand anAtari 400 or 800 with mini-mum programmable memoryto a full 64 K memory byusing 4116 chips. To this ex-pansion board, I would alsolike to add RS-232C circuitryto handle a printer and

modem. Of course, it wouldneed its own power supply.

I am a technician with agood background in digitalelectronics but not a circuitdesigner. Where can 1 findthe necessary schematic andparts list?Emanuel SofterRockaway NY

Expanding the memoryand adding RS-232C to theAtari are two completely dif-ferent problems, each requir-ing diverse amounts of talent.The 6502 has no internal re-fresh logic, as does the Z80.External refresh logic must beadded.

An RS-232C serial port canbe added fairly easily to theexpansion connector on theside of the Atari if the propersoftware is added to the unit.One company that has beenworking on this is the CodeWorks, POB 550, Goleta CA93017. I suggest that youwrite the Code Works (atten-tion Ron Jefferies) askingabout its serial port for theAtari. It should be fairly inex-pensive because it's practical-ly all software.

Presently, it is cheaper touse static memory on theAtari. Whether this situationcontinues will be determinedby the prices of dynamic ver-sus static memory, the devel-opment of an inexpensiverefresh method, or the evolu-tion of new quasistatic pro-grammable memories, suchas the Zilog 7.6132. If anyreaders have a good circuitfor using dynamic memorywith a 6502, I'd appreciateseeing it. . . . Steve

Little ProblemsCause Big Ones

Dear Steve,

We have a problem withour 6800 microcomputer.

360 September 1981 © BYTE Publications Inc

Circle 258 on inquiry card.

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□ 1 year (6 issues) $15 $17 $19

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RACET SORTS - RACET UTILITIES — RACETcomputes — RACETSORTS — RACET UTILITIES - RACET computes — RACET SORTS — RACET UTILITIES — RACET computes - -n

FIELD PROVEN!!

10 MEGABYTES and MORE for the TRS-80* Model II

plus SHARED ACCESS to HARD DISK DRIVE

Hard/Soft Disk System (HSDS) Software allows access as single drive. You canhave that 10 Megabyte continuous file - that 50,000 name maillist or inventory! Ora directory with 1000 entries! All completely compatible with TRSDOS 2.0 BASIC.You can mix floppy and hard disk drives. Includes special utilities including HPURGE,DCS Directory Catalog System, HZAP Hard Disk Superzap, and many specialformatting options. Three to eight times faster than floppy! RACET quality.

HARD DISK DRIVE & CONTROLLER $5995. Second User $595.

HSDS Software $400. (Note: HSDS now also available for C0RVUS drives!!)

INFINITE BASIC (Mod I & III Tape or Disk) Mod I $50.00, Mod III $60.00

Extends Level II BASIC with complete MATRIX functions and 50 more stringfunctions. Includes RACET machine language sorts! Sort 1000 elements in 9seconds!! Select only functions you want to optimize memory usage.

INFINITE BUSINESS (Requires Infinite BASIC)Complete printer pagination controls — auto headers,Packed decimal arithmetic — 127 digit accuracy +,of sorted and unsorted arrays. Hash codes.

Mod I & III $30.00

footers, page numbers.-, *, /. Binary search

BASIC CROSS REFERENCE UTILITY (Mod II 64K) $50.00

" SEEK and FIND functions for Variables, Line Numbers, Strings, Keywords. 'AH': options available for line numbers and variables. Load from BASIC — Call with'CTRL'R. Output to screen or printer!

DSM Mod I $75.00, Mod II $150.00, Mod III $90.00

Disk Sort/Merge for RANDOM files. All machine language stand-alone package forI sorting speed. Establish sort specification in simple BASIC command File. Execute; from DOS. Only operator action to sort is to change diskettes when requested!■ Handles multiple diskette files! Super fast sort times — improved disk 1/0 times3 make this the fastest Disk Sort/Merge available on your TRS.ii (Mod I Min 32K 2-drive system. Mod II 64K 1-drive. Mod III 32K 1-drive)

\ GSF (Mod I & III Tape or Disk - Specify Memory Size)

I Mod I $25; Mod II $50; Mod III $30

I Generalized Subroutine Facilities. The STANDARD against which all other sorts are

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j Mod II includes USR PEEKS and POKES. Includes sample programs.

i RACET SORTS — RACET UTILITIES — RACET computes — RACET SORTS — RACET UTILITIES — RACET computes — RACET SORTS — RACET UTILITIES — RACET computes -

DISCAT (32K 1 -drive Min) Mod I, III $50.00

This comprehensive Diskette Cataloguing/Indexing utility allows the user to keeptrack of thousands of programs in a categorized library. Machine language programworks with all TRSDOS and NEWD0S versions. Files include program names andextensions, program length, diskette numbers, front and back, and diskette free space.

KFS-80 (1-drive 32K Min — Mod II 64K) Mod I, III $100.00; Mod II $175.00

The keyed file system provides keyed and sequential access to multiple files. Providesthe programmer with a powerful disk handling facility for development of data baseapplications. Binary tree index system provides rapid access to file records.

MAILLIST (1-drive 32K Min - Mod II 64K) . Mod |, III $75,00; Mod II $150.00This ISAM-based maillist minimizes disk access'times. Four keys — no separatesorting. Supports 9 - dig i t zip code and 3-digit state code, ,%tp 30 attributes. Maskand query selection. Record access times under 4 seconds!!

C0MPR0C (locill & Mod III — Disk only) Mod I $20; Mod III $30

Command Processor. Auto your disk to perform any sequence of instructions thatyou can give from the keyboard. DIR, FREE, pause wdiii.ni er input BASIC, No.of FILES and MEM SIZE. RUN program, respond to i inents, BREAK,

return to DOSlfete, Includes lowercase driver software, debounce and screenprint!

UTILITY PACKAGE (Mod H64K) $150.00

Important enhancements to the Mod II. The file recovery capabilities alone will payfor ihe package in even one-application! Fully documented in 124 page manual!XHIT, XGAT, XC0PY. and; SUPERZAP are used to reconstruct or recover date frombad diskettes' XC0PY provides-multi-file copies, 'Wild-card- mask select, absolutesector mode and other features; SUPERZAP allows exariiine/cfiangeany sector ondiskette include track-0, and absolute di-,1 . -ecovery. DCS

builds consolidated tiire:^M^^^mmf(0m&§&^^^WvlW^\e display orlisting sorted by disk name or file name plus more. Change Disk ID with DISKID.XCREATE preallocates files and sets 'L0F' to end to speed disk accesses. DEBUGIIadds single step, trace, subroutine calling, program looping, dynamic disassemblyand more!!

DEVELOPMENT PACKAGE (Mod II 64K) $125.00

Includes RACET machine language SUPERZAP, Apparat Disassembler, and ModelII interface to the Microsoft 'Editor Assembler Plus' software package includinguploading services and patches for Disk I/O.

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Circle 311 on inquiry card.

Ask "VTE

This problem appears to beentirely within the computeritself. Local experts and Tech-nical System Consultants (itwrote the software) all seemto be baffled by the problem.

The computer is a SwTPC(Southwest Technical Prod-ucts Corporation) 6800microcomputer wth 32 Kbytes of programmable mem-ory (two 4 K-byte boards at0000 to 1FFF hexadecimal andthree 8 K boards at 2000 to7FFF), an A2 processor boardwith SwTBUG monitor, MP-C interface, and MF-68 dualdisk drives. The system runsunder Flex 1.0. The peripher-als are: CT64 terminal, AC30cassette interface, GE Term-inet 300 hard-copy terminal,and a PR40 parallel printer.

Running MEMTESTl indi-cates one small problem ataddress 3C2D hexadecimal,but, other than that, thereappear to be no problems.

The problem appears whenusing the PRINT statementrunning under Disc BASIC3.0 and all versions of 8 KBASIC. When running a pro-gram with any more than 25characters in a PRINT state-ment anywhere in the pro-gram, one of the followinghappens:

• The CT64 terminal will gointo numerous control char-acter gyrations after printingthe first 25 characters.

• Both printers print the same"garbage" after the 25 char-

acters. Each line printed willhave the same "garbage"characters after the first 25characters.

Strangely enough, thisproblem with the terminaland the printers does not oc-cur with the LIST commandon any of the aforementionedversions of BASIC. When Iuse the 4 K-byte version, Iencounter no problems at allwith the PRINT statement.Dave CoultishOttawa, Ontario, Canada

/ asked our local SwTPCguru, Leo Taylor, to providean answer. . . . Steve

Unfortunately, I can't tellyou anything solid, because 1do not have the BASIC youare using. I can, however,offer a few suggestions.

I suspect you have con-fused a few people with yoursoftware description. To thebest of my knowledge, Iguess you have Miniflex andSwTPC BASIC 3.0. Manypeople are confused betweenversions of Flex. If you have5-inch floppy-disk drives,you can't have Flex 1.0because it requires 8-inchdrives and memory at hexa-decimal A000. TSC did notwrite BASIC 3.0; it was writ-ten by Rober Uterwick andadapted by SwTPC.

There is never a "smallmemory problem." BASIChas a way of finding memory

problems that defy any othermeans of detection. Sinceyou mentioned the memoryerror, you probably haven'tswapped boards to eliminateit as a suspect. You haveenough memory to removeany one board and still havethe required 12 K starting ataddress 0000 and 4 K athexadecimal 7000. TheBASIC you are using willscan for end-of-memory. If itfinds a byte it considers bad,it stops scanning, backs upone address, and loads itsstack. If the end-of-memoryis near the start of a page(such as 3C2D), BASIC willfail to reserve enough stackspace. This can cause all sortsof problems. Thus, a minormemory problem becomes amajor malfunction. . . . LeoTaylor

Control Search

Dear Steve,

My company has beenlooking for a way to com-municate with a robot byusing radio control. We were

hoping that you might knowof an integrated circuit thatcan be used. We need three ormore digitally proportionalchannels that can be easilycontrolled by a computer.Michael DubnoBronx NY

National Semiconductorhas recently introduced a setof devices for the remote-controlled toy market thatmay be of interest to you.The LM1871 (transmitter)and LM1872 (receiver) havethe following capabilities:

• two analog channels

• two digital channels

• operates on 27, 49, or72 MHz band

• regulated pulse-widthmodulation radio-frequencyoutput

It doesn't have three ana-log channels as you re-quested, but it has a lot ofpower for an 18-pin chip. Irecommend that you contactyour local National Semicon-ductor sales representativefor pricing and availability.. . . Steve!

In "Ask BYTE," Steve Ciarcia answers questions on any area ofmicrocomputing. The most representative questions receivedeach month will be answered and published. Do you have a nag-ging problem? Send your inquiry to:

Ask BYTE

c/o Steve Ciarcia

POB 582

Glastonbury CT 06033If you are a subscriber to The Source, send your questions byelectronic mail or chat with Steve (TCE317) directly. Due to thehigh volume of inquiries, personal replies cannot be given. Besure to include "Ask BYTE" in the address.

6809 SYSTEMS (^ 6809 SYSTEMS (^ 6809 SYSTEMS (^ 6809 SYSTEMS

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The Company that deliversQuality Electronic products since 1975.

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Arithmetic processors, and 4 PROM/ROM/RAM sockets that can hold up to 32KB of monitor or user software.VARIETY: you can have 32KB, 56KB, 128KB and up ol static RAM. You can use 5" and/or 8" disk drives, single or doubledensity, single or double sided, and single or double tracking with GIMIX disk controllers. You have a wide choice of serial orparallel I/O cards.

EXPANDABILITY: You can add memory, l/Os, Video or Graphics cards, Arithmetic processors, additional drive capacity, and otherhardware now or in the future to this SS50 bus structured system from GIMIX or other SS50 bus compatible manufacturers. 1337 WEST 37th PLACE, CHICAGO, IL 60609SOFTWARE VERSATILITY: GIMIX systems can use TSC's FLEX or UNIFLEX and MICROWARE'S OS-9 operating systems. A wide (312) 927-5510 • TWX 910-221-4055variety of software and languages is available for these systems.

QUALITY: All boards are assembled, burned-in, and tested and feature GOLD PLATED BUS CONNECTORS. Only top quality com-ponents are used and all boards are fully buffered for maximum system expansion. All boards come complete with bus connectorsand all necessary instruction and documentation. Flex and Unillex are Irademarks of Technical Systems

GIMIX designs, manufactures and tests, in-house, their complete line of products. Complete systems are available to fit your Consultants inc. 0S9 is a irademark ol Microware Inc. Seeneeds. Please contact the factory if you have any special requirements. ,ne'r ads ,or olner GIMIX compatible sottware.

and GHOST" are registered trademarksof GIMIX Inc.

For GIMIX compatible software see Technical Systems Consultants ad page 199.

362 September 1981 © BYTE Publications Inc

Circle 148 on inquiry card.

small ad:

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8 Disk Drives to choose from

82902S 1300.00

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Quad Ram equals 4 Mem. Mods 95.00Memory Modules for 41 C

HP-97 Progrmble Printer 750.00

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16K- 32K-48K-96K-128KDrive with controller DOS 3.3 ami others.80 column cardsDow Jones & Qtiote ReporterDC Hayes Micromorietn II _^*-—.J?8»and others. . .Graphics TabletPascal and Fortran

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APPLE III 96K and 128K "CALL US"

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Tl 99/4 Home Computer 950.00 S379.95

ID" Color Monitor lor 99/4 650.00 319.95

32K Exp. Mem. Module 399.95 314.95

Extended Basic, a MUST for 100.00 75.00

32K Module

Speech Synthesizer 150.00 129.96

Disk Memory Drive 500.00 397.95

RF Modulator G9.50 49.50

Telephone Coupler (Modem) 225.00 189.95

Printer Isuhd state! -100.00 319.95

TI-59 Progrmnle Calculator 295.00 199.95

TI-58C Progrmble Calculator 130.00 93.95

PC-100C Prntr/Plotr lor 69/58 225.00 149.95

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MBA Finance & Business 70.00 51.95

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Tl 55 Slide Rule 40.00 32.95

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space for floppy100-G 12" Green, 12 MHz 199.00 159.95300-G 12" Green. 18 MHz 249.00 189.95Color I 13" Color, NTSC comp.449.00 329.95

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Circle 263 on inquiry card.

BYTE September 1981 363

Circle 167 on inquiry card.

PRODUCTS

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New! Model 950 995.00

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MODEL DESCRIPTION (ALL ASSEMBLED 8, TESTED) PRICE

MF+DD12A . ..25 A. Mainframe: 12 Slot, S100, Dual 8" Drive .$625.00

MF+18A 25 A Tabletop Mainframe; 18 Slot, S100 450.00

MF+12A 25 A Mainframe; 12 Slot. S100, Dual 5" Drive .. 450.00

Z+80A Single Board. Z-80 Computer 2/4 Mhz, S-100 .. 18500

Z+80A/2.2 ... .Monitor Program for Z+80A & Tarbell or VF-1 .... 30.00

RAM 32 32K Static RAM Board. Low Power, S-100 499,00

QTCIOA 2 Serial & 4 Parallel Port I/O. S-100 339.00

QTCCCSA ... .Clock Calendar Board, S-100 125.00

QTCCCAA ... .Clock Calendar Board, for Apple 125.00

QTCCCTRS80 Ciock Calendar Module for TRS-80 125 00

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MODEL DESCRIPTION lALL ASSEMBLED & TESTED) PRICE

V300/25 .. Letter Quality Printer, 25 CPS $1895.00

V300/45 ..Letter Quality Printer, 45 CPS 2195 00

V-DRIVE .. Dual 8" Disk Cabinet, Power Supply, Rack Mountable • ■ ■ 375.00

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RAM 16...16K Static RAM, S-100 $189.00

RAM 16C . Low Power (CMOS) Version of RAM 16, 1.3 Watt.... 259.00

RAM 65...16K Static RAM, I/O Port Bank Select, S-100 169.00

RAM 65C . Low Power (CMOS) Version of RAM 65. 1A Watl ... 279.00RAM 32...32K Low Power 8/16 Bit Static.RAM, Fully IEEE 696 499.00

RAM 256 . .256K 8/16 Bit Dynamic RAM, Fully IEEE 696 1295.00

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Minimum Order is $15.00. Prices quoted do not include shippingand handling. Foreign orders require prepayment by MICR orMoney Order in U.S. funds. Purchase Orders accepted from U.S.Government & firms with published A1 Rating from Dunn &Bradstreet. All other orders require prepayment, charge card,or COD shipment.

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Books Received

Apple Crunch, novel byFrederic Vincent Huber. NewYork: Seaview Books, 1981;

15 by 22 cm, 264 pages, hard-cover, ISBN 0-87223-687-O,$10.95.

Calculator Clout: Pro-gramming Methods for YourProgrammable, Maurice DWeir. Englewood Cliffs NJ:Prentice-Hall, 1981; 18.5 by24.5 cm, 235 pages, hard-cover, ISBN 0-13-110411-X,$17.95; softcover, ISBN 0-13-110403-9, $8.95.

Computers for Everybody,Jerry Willis and Merl Miller.Beaverton OR: DilithiumPress, 1981; 14 by 22 cm, 173pages, softcover, ISBN 0-918398-49-5, $4.95.

Computer Literacy: Prob-lem-Solving with Computers,C E Horn and J L Poirot.Austin TX: Sterling SwiftPublications, 1981; 18.5 by23.5 cm, 304 pages, soft-cover, ISBN 0-88408-133-8,$13.95.

Computer Solution ofLarge Sparse Positive Defi-nite Systems, Alan Georgeand Joseph W Liu. Engle-wood Cliffs NJ: Prentice-Hall, 1981; 16 by 23.5 cm,324 pages, hardcover, ISBN0-13-165274-5, $24.95.

The Devil's DP Dictionary,Stan Kelly-Bootle. NewYork: McGraw-Hill, 1981;13.5 by 20.5 cm, 141 pages,softcover, ISBN 0-07-034022-6,$7.50.

Electronic Circuits NoteBook, Proven Designs forSystems Applications, editedby Samuel Weber. NewYork: McGraw-Hill, 1981; 22by 28 cm, 344 pages, hard-cover, ISBN 0-07-019244-8,$32.50.

Manual of PharmacologicCalculations with ComputerPrograms, Ronald J Tallaridaand Rodney B Murray. NewYork: Springer-Verlag, 1981;

16 by 24.5 cm, 150 pages,hardcover, ISBN 0-387-90500-6, $17.50.

Microsoft FORTRAN, PaulM Chirlian. Beaverton OR:Dilithium Press, 1981; 14 by22 cm, 333 pages, softcover,ISBN 0-918398-46-0, $14.95.

Outland, The Movie Novel,edited by Richard J Anobile,from the screenplay by PeterHyams. New York: WarnerBooks, 1981; 22 by 27.5 cm,160 pages, softcover, ISBN0-446-97829-9, $9.95.

Program Flow Analysis:Theory and Applications, S SMuchnick and N D Jones. En-glewood Cliffs NJ: Prentice-Hall, 1981; 16 by 23.5 cm,418 pages, hardcover, ISBN0-13-729681-9, $23.50.

Scientific Analysis for Pro-grammable Calculators withAlgebraic Operating Sys-tems, H R Meek. EnglewoodCliffs NJ: Prentice-Hall,1981; 18.5 by 24.5 cm, 175pages, hardcover, ISBN 0-13-796417-X, $15.95; softcover,ISBN 0-13-796409-9, $7.95.

Software Metrics, editedby A J Perlis, F G Sayward,and M Shaw. CambridgeMA: The MIT Press, 1981; 16by 23.5 cm, 404 pages, hard-cover, ISBN 0-262-16083-8,$25.

Thirty-Two BASIC Pro-grams for the Exidy Sorcerer,T Rugg, P Feldman, and KMcCabe. Beaverton OR: Di-lithium Press, 1981; 14 by 22cm, 265 pages, softcover,ISBN 0-918398-35-5, $16.95.1

This is a list of booksreceived at BYTE Publica-tions during this pastmonth. Although the list isnot meant to be exhaustive,its purpose is to acquaintBYTE readers with recentlypublished titles in computerscience and related fields.We regret that we cannotreview or comment on allthe books we receive; in-stead, this list is meant to bea monthly acknowledgmentof these books and the pub-lishers who sent them.

364 September 1981 © BYTE Publications Inc

Circle 127 on inquiry card.

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CATCH THE S-100 INC. BUS!

S.D. Systems 80x24 Video BoardA&T

S.D. Systems Versafloppy IIDouble Density Disk Controllerw/SDOS, DDBI0S, VDIAG3, &Monitor; A&T

Shugart SA 800/801R Bare Drive

IMC Disk Box for 51/4" Drives

SSM I/0-4 Kit 2 Parallel + 2 Serial

Mullen TB-4 Extender Kit w/Probe

OUR

LIST

SPECIAL

PRICE

CASH

PRICE

556.00 420.00

500.00600.00

39.00210.00

59.00

380.00399.00

29.00168.00

47.00

Subject to Available Quantities • Prices Quoted Include Cash Discounts.Shipping & Insurance Extra.

We carry all major lines such as

S.D. Systems, Cromemco, Ithaca Intersyslems, North Star,

Sanyo, ECT, TEI, Godbout, Thinker Toys, SSM.

For a special cash price, telephone us.

Please note our new address.

S-JDD,inc.

14425 North 79th Street, Suite B

Scottsdale, Arizona 85260

800-582-3138 • 602-991-7870

Hours: Mon. - Fri. — 9 a.m. to 6 p.m. MST

EDITOR, ASSEMBLER AND MORE!

SOFTWARE DEVELOPMENT SYSTEM

The Micro Works Software Development System (SDS80C) is a complete 6809editor, assembler and monitor package contained in one Color Computer programpack! Vastly superior to RAM-based assemblers/editors, the SDS80C is non-volatile, meaning that if your application program bombs, it can't destroy youreditor/assembler. Plus it leaves almost all of 16K or 32K RAM free for yourprogram. Since all three programs, editor, assembler and monitor are co-resident,we eliminate tedious program loading when going back and forth from editing toassembly and debugging!

The powerful screen-oriented Editor features finds, changes, moves, copys andmuch more. All keys have convenient auto repeat (typamatic), and since no linenumbers are required, the full width of the screen may be used to generate wellcommented code.

The Assembler features all of the following: complete 6809 instruction set;complete 6800 set supported for cross-assembly; conditional assembly; locallabels; assembly to cassette tape or to memory; listing to screen or printer; andmnemonic error codes instead of numbers.

The versatile ABUG monitor is a compact version of CBUG, tailored for debuggingprograms generated by the Assembler and Editor. It features examine/change ofmemory or registers, cassette load and save, breakpoints and more. SDS80CPrice: $89.95

CRACK THOSE ROMS!

SOURCE GENERATOR: This package is a disassembler which runs on the colorcomputer and generates your own source listing of the BASIC interpreter ROM.Also included is a documentation package which gives useful ROM entry points,complete memory map, I/O hardware details and more. A16K system is requiredfor the use of this cassette. 80C Disassembler Price: $49.95

CBUG IS HERE!

MONITOR TAPE: A cassette tape which allows you to directly access memory, I/Oand registers with a formatted hex display. Great for machine languageprogramming, debugging and learning. It can also send/receive RS232 at up to9600 baud, including nost system download/upload. 19 commands in all.Relocatable and reentrant. CBUG Tape Price: $29.95

MONITOR ROM: The same program as above, supplied in 2716 EPR0M. Thisallows you to use the entire RAM space. And you don t need to re-load the monitoreach time you use it. The EPR0M plugs into the Extended Basic ROM Socket or amodified ROMPACK. CBUG ROM Price: $39.95

LEARN 6809!

6809 ASSEMBLY LANGUAGE PROGRAMMING,

by Lance Leventhal, contains the most comprehen-sive reference material available for programmingyour Color Computer. Price: $16.95

THE

PARALLEL O!

USE A PARALLEL PRINTER with your ColorComputerl Adaptor box plugs into the serial port andallows use of Centronics/Radio Shack compatibleprinters with parallel interface. Assembled andtested. PI80C Price: $69.96

GOOD STUFF!

3SK RAM!

MEMORY UPGRADE KITS: Consisting of 4116200ns. integrated circuits, with instructions forinstallation. 4K-16K Kit Price: $39.95. 16K-32KKit (requires soldering experience) Price: $39.95

WE SHIP FROM STOCK!

Master Charge/Visa and COD Accepted

P.O. BOX 1110 DEL MAR, CA 92014 714-942-2400

Circle 227 on inquiry card.

BYTE September 1981 365

Circle 367 on inquiry card.

THE TSEHARDSIDE 1982 MICROCOMPUTER BUYER'S GUIDEis now available! We've included suchvaluable information as print samplesfrom each of the printers we carry,feature-by-feature comparisons of Micro-Computer systems in an easy-to-readtable format, an informative article onMicros, and pages and pages of completeproduct descriptions.

We're making this valuable referenceavailable for only $2.95 (refundable onyour next purchase from TSEHARDSIDE.)Charge customers are welcome to call ourtoll-free number: 1-800-258-1790 (in NH call673-5144) THE TSEHARDSIDE 1982MICROCOMPUTER BUYER'S GUIDE willsoon arrive at your address via first classmail.

Send to:

TS€JHP)RDSID€

Dept. C, 14 South StreetMilford. NH 03055

L.

Yes! Send me the

TSEHARDSIDE 1982 Micro-Computer Buyers Guide.

I've enclosed $2.95 Please send only your FREE Price List

Charge to my credit card MasterCard Visa

Card No.

Interbank No. Exp. Date

Signature

Name

Address

City

State Zip Code

B9

.J

BUS-TO-BUS COMMUNICATION

AA\ V\ S \V« YW^UJ. V.i iV. Vi!

with the

P&T-488

VSiliiiiS \\ V\1A » \\ \ Y\ V

S-100 bus

CP/NTCromemcoNorth Star

■ Inexpensive S-100 computers can now communicate with theIEEE-488 instrumentation bus. The P&T-488 meets the IEEE-4881980 standard for controller, listener, and talker.

■ "Canned" software allows simple communication with the488 bus from Basic, Pascal, and other high level languages.

■ Special features include an interactive busmonitor programand a functional self-test program.

Price for (1) PST-488 with software, assembled and tested: $450(domestic price) FOB Goleta, CA.

CP/M is a registered trademark of Digital Research.

PICKLES & TROUT

P. O. BOX 1206, GOLETA. CA 93116, (805) 685-4641

^ROljf

Clubs andNewsletters

Join a Georgian Club

The Statesboro TRS-80Users Group is interested inall aspects of TRS-80 comput-ers, especially word-process-ing and business applications.Contact the club c/o DrRussell A Dewey, 223 NEdgewood Dr, StatesboroGA 30458, (912) 681-3631.

Apple Guild

The Apple Guild promotesthe interchange of informa-tion and applications amongApple users. The Guild main-tains a collection of hard-copy material and software atthe Apple Resource Center.The Resource Center islocated at Massasoit Com-munity College, Brockton,Massachusetts. The Guildpublishes a quarterly journaland supports a telecommuni-cations system at (617)767-1303. Contact the AppleGuild, POB 371, WeymouthMA 02188.

Ohio Apples

The NEO Apple Corps isdevoted to Apple computers.The Corps publishes a news-letter called Apple Bits. Con-tact the group at 21750 MillerAve, Euclid OH 44119, (216)486-2317.

MlcropollsUsers Group

Members of the MicropolisUsers Group use Micropolisdisk drives in their computersystems. The group offers itsmembers a monthly newslet-ter and discounts on soft-ware. Also available are li-brary disks and directories ofsoftware vendors and group

366 September 1981 © BYTE Publications Inc

Circle 293 on inquiry card.

Circle 342 on inquiry card.

Apple Dealers.

We NeedYou

■topple computer

We've written TRA\/§, a complete surveying packagethat is second to none. It has all the routines neededfor surveying. It's menu driven and heavily prompted.The manual was written in straightforward every daysurveying language by a third generation surveyorwho has been working with computers since 1965.

Surveyors are generally accustomed to dedicated calculatorsor computers. Most of them are just doing their sur-veying and engineering computations and are not util-izing the capability of a general purpose computer likethe Apple to do payroll, G/L, A/P, A/R, word processingor iob costing.

That's where you come in. You sell 'em the hardwareand the other software and we'll help you sell 'em ourprogram. If you or your customer have questions, we'llbe happy to answer them for you.

TRAV is no stranger to surveyors. We're advertising inall national surveying publications. We have satisfied usersall over the U.S.

Our discounts are great.

Call or write for a user manual.

Surveyors Supply Co.

P.O. Drawer 808 Hwy 64 at OldApex, N.C. (919) 362-7000

Circle 195 on inquiry card.

LDP88 8088 CPU BOARD

• 8088 CPU 5 MHz operation upgradeable to 8 MHz • 9 vectored Inter-rupts • Fully complies with IEEE 696 electrical and timing specs • RS232serial port with modem controls • 1K bytes of static RAM • 2 EPROMsockets (2716 or 2732) • 8087 upgrade kit available In Sept. • 8 bit buseases Interface to other S100 bus boards • 1MByte address space • 65KI/O ports

64/256K MEMORY

• 8 or 16 bit operation • Meets all IEEE 696 specs • Access time 350 nsfrom PSYNC low • Intel 8203 dynamic RAM controller • 24 or 16 bit ad-dress decoding • No wait states with 5 MHz 8088 or 8086 • Parity withError Interrupt generation • No DMA RESTRICTIONS • 64K board is up-gradeable to 256 Kbyte board

HAZITALL

• 2 Serial RS232 ports • 2 parallel ports with handshake control • Mathprocessor support (8231/9511 or B232/9512) • WINCHESTER DISK support

• Real time programmable Interrupt • Clock/calendar with battery backup • Synchronous data communication supported

LDP72 FLOPPY DISKCONTROLLER

• IBM compatible single and double density format • Single or doublesided drives • Programmable data record length (128 to 8192 bytes/sector) • Multl sector and multi track transfer capability • Parallel seekson up to 4 drives • On board digital data separator • Software selectablesingle or double density operation • Separate connectors for 5V«" and 8"drives • Software selection of standard or mlnldrlves allowing mixing ofboth drives on a single controller

Software support for 86-DOS and CP/M-86.

CP/M-86 $250 86-DOS $195.00

LDP88 $349.95 LDP72 $274.95

HAZITALL $325.00 LDP64K RAM $695.00

LDP128KRAM $1295.00 LDP256K RAM $2095.00Complete systems also available.

CP/M-86 Is a trademark of Digital Research

86-DOS Is a trademark of Seattle Computer Products

LOMAS

DATA

PRODUCTS

11 Cross StreetWestborough, MA 01581Telephone: (617) 366-4335

SAVE $$

^cippkz computer

16K APPLE II32K APPLE II48K APPLE IIDISKW/CONTROLLERDISK ONLYAPPLESOFT CARDINTEGER CARDPASCAL SYSTEMSILENTYPE PRINTERHAYES MICROMODEMZ-80 SOFTCARDVIDEX80COL BRD.16KRAM BOARD

RAM MEMORY

FOR TRS-80, APPLE II16KSET4116'S(200NS)

1089.001134.001179.00535.00455.00159.00159.00425.00525.00295.00295.00295.00169.00

34.95

DISCOUNT PRICES

SAVE $$

ATARr

40016K 349.00

80016K 759.00

410 Recorder 64.00

815 Disk 1199.00

810 Disk 489.00

822 Printer 359.00

825 Printer 779.00

830 Modem 159.00850 Interface Module 179.00

CX853 RAM 85.00

CX70 Light Pen 64.00

CX30 Paddle 18.00

CX40 Joystick 18.00

VERBATIM DISKETTES

Box of 10 51/4" 29.50

Box of 10 8" 39.50

North Star Computers

HR2-2D-32K 2795.00

HR2-20-48K 2956.00

HR2-2D-64K 3145.00

HR2-2Q-32K 2975.00

HR2-2Q-48K 3165.00

HR2-2Q-64K 3360.00

HRAM32K 469.00

HRAM48K 662.00

HRAM64K 849.00

HDS-18 HARD DISK 4025.00

MDS-DRV-D 495.00

MDS-DRV-Q 665.00

ADC-1-D 740.00

ADC-2-D 995.00

ADC-1-Q 795.00

ADC-2-Q 1285.00

PRINTERS

EPSON MX-70EPSON MX-80EPSON MX-80 FTGRAFTRAXINTERFACE (APPLE)CABLE

399.00

499.00

599.00

90.00

75.00

22.50

CENTRONICS 737-1CENTRONICS 737-3

795.00855.00

IDS445GIDS460GIDS560G

815.001195.001450.00

NEC 5510 W/TRACTORS 2650.00NEC 5520 KSR W/TRAC. 2995.00

QUME 5/45 SPRINTFORMS TRACTOR

2675.00195.00

STARWRITER W/TRAC.STARWRITER W/O

1695.00

TRACTOR

1500.00

General Information:

We carry a large selection of hard-ware and software by other com-panies. Send for our catalog.We are an authorized repair center forAPPLE, ATARI, NORTH STAR, ANDEPSON.

PRICES SUBJECT TO CHANGE WITHOUT NOTICE. MARYLAND RESIDENTS ADD 5% SALES TAX

FREDERICK 5726 industry lane

COMPUTER FREDERICK, MD. 21701

PRODUCTS, INC.

Store Hours:

MON. THRU THURS. 9:30 AM-9:00 PMFRI. AND SAT. 9:30 AM —5:00 PM

TO ORDER CALL: (301) 694-8884

Circle 144 on Inquiry card.

BYTE September 1981 367

Circle 83 on inquiry card.

ATTENTION GOVERNMENT D PUSERS AND PURCHASERS

We represent many fine micro products and manufacturerson the U.S. Government's GSA Schedule, including

Apple, Cromemco, Micropolisand Seequa Computers

Purchasing from the Schedule will save you the timeconsumed by the bid process. Products shipped throughoutthe United States and world-wide. Visit or write any of ourstores for more information or to receive our catalogue ofproducts represented.

Computers,

the dependable store

257 West Street, Annapolis, MD 21401 - (301) 268-6505

13A Allegheny Avenue, Towson, MD 21204 - (301) 296-0520

9330 Georgia Avenue, Silver Spring, MD 20910 - (301) 588-3748

6671 Backlick Road, Springfield, VA 22150 - (703) 644-5500

Plaza 38, 2442 Route 38, Cherry Hill, NJ 08002 - (609) 779-0023

Callers outside metropolitan areas served by our stores

Please call (301) 268-5801

Career Opportunities Available * An Equal Opportunity Employer

LETTER QUALITY PRINTER

• DUAL USE. A PRINTER AND A TYPEWRITER

• SELF TEST PROGRAM BUILT IN

The BYTEWRITER is a printer consisting of a microprocessor controlledassembly internally connected to an SCM Coronamatic aooo officetypewriter.

$795

OTHER FEATURES

- Back space.Parallel input.

- Pin compatible with

TRS-80 expansion interface.

- Typewriter operation with

nothing to disconnect.

rO ORDER

Send certified check or money order.Personal checks take 2 weeks.We do not ship C.O.D.Add S lO for shipping and handling incontinental U.S.A.N.Y.S. residents add 7% sales tax.

BYTEWRITER

125 NORTH VIEW RD., ITHACA, N.Y.(607) 272-1 132

14850

scm Coronamatic 8O00 is a trademark of SCM Corp.

TRS-80 Is a trademark of Tandy Corp.

BYTEWRITER is a trademark of Williams Laboratories.

members. Contact the Micro-polis Users Group at 604Springwood Cr, HuntsvilleAL 35803, (205) 883-2621.

MCMS

MCMS (Military/CivilianMicrocomputer Society) isdevoted to the exchange ofideas and information aboutall types of computers. Noparticular microcomputer isemphasized. Contact theMilitary/Civilian Microcom-puter Society, Gunter AFS,AL 36114, or call Jim Wolfeat (205) 279-4816.

Lists of UsedMicrocomputers

The Used Computer Ex-change is a listing service thatputs you in direct contactwith sellers. Customers pay$5 for quotes on completedtransactions and for full cur-rent listings. Sellers pay acommission only if a transac-tion is completed with abuyer referred by the Ex-change.

The Used Computer Ex-change lists any microcom-puter hardware that original-ly sold in the $400 to $25,000price range. Contact the UsedComputer Exchange at 2329Hunters Woods Plz, RestonVA 22091, (800) 327-9191,ext 61; in Virginia, (703)471-0044.

1802 Fans

The VIP Hobby ComputerAssociation is made up ofusers of the RCA VIP andother 1802-based microcom-puters. The group's newslet-ter, Viper, contains pro-grams, advice, and helpfulhints. Membership fees are$12 per year, which includesthe newsletter. Contact theVIP Hobby Computer Asso-

368 September 1981 © BYTE Publications Inc

Circle 49 on inquiry card.

Circle 65 on inquiry card.

Circle 203 on inquiry card.

J%. Components Express, Inc

^~ "Have you Hissed your computer lately?"

1380 E. Edinger. UnitCC Santa Ana. CA 92705(714) 558-3972

BROAD BAND MICROWAVERECEIVER SYSTEM1.8GHZ to 2.4 GHZ

only$295.00

RANGE:SCOPE:

With built-in-converter to channel2, 3, or 4 of any standard TV set.

Line of sight to 250 miles.

Will receive within the frequency band from satelites, primarymicrowave stations, and repeater microwave boosterstations

CONTENTS. Packaged in 19"x19"x4 1/2" corrugated carton completewith:

300 Ohm to 75 Ohm Adapter

750 Ohm to 300 Ohm Adapter

60 Feet Coax Cable with Connectors

3 Feet Coax Cable with Connectors

• 24" Dish

• Feed-Horn Receiver

• Mounting Bracket

• Mounting Clamp

• Instructions

WARRANTY:

180 days for all factory defects and electronic failures for normal

useage and handling. Defective sub assemblies will be replaced

with new or re-manufactured sub assembly on a 48 hour exchange

guarantee.

This system is not a kit and requires no additional devices or equipment other thana TV set to place in operation. DEALER INQUIRIES INVITED.

GET THE BUGOUT OF YOURPROGRA*"

Locate the bus m your

prosram quickly with the

all-new BUG CATCHER.

Reliable and easy to use,

this timesaver fits easily

in pocket or case.

Functional for any

computer where EPROMs

are used. Capable ofhalting the cpu at anyspecific address. Stoplosing time and patience.BUG CATCHER is theefficient answer.$195 complete (plusapplicable sales tax).

els ; ii ;n \

MARTEC SYSTEMS, INC.

P.O. BOX 2069, NEWBURGH, NY 12550 (914)265-4044

PMC PERSONAL COMPUTER

Ideal for small businesses, schools, colleges, homes, etc.Suitable for the experienced, inexperienced, hobbyist,teacher, etc ^^L -x.

EG3000

user RAMMicrosoftI Level IIsoftware compatible •Hugerange of software already available • Self contained, PSU,UHF modulator, and cassette •Simply plugs into videomonitor or UHF TV •Full expansion to disks and printer• Absolutely complete - lust fit into mains plug.

COMPUTERPOWER THATONCE FILLED A ROOMCAN NOW BE CARRIED IN YOUR POCKET!

• Programs in BASIC • "QWERTY" AlphabeticKeyboard •1.9K Random Access Memory

• Long Battery Life.

TV GAME BREAK OUT KIT

Has got to be one of the world's

greatest TV games You really get

hooked Has also 4 other pinball

games and lots of options.

Good kit for up grading old

amusement games

MINI KIT PCB. sound & vision modulator, memory chipand de code chip Very simple to construct $30.00OR PCB $6.00 MAIN LSI $17.00

TTL SALE

74LS0075LS0474LS0574LS1074LS32

$0.15$0.15$0.20$0.23$0.35

74LS74

74LS86

74LS93

74LS157

74LS165

$0.45$0.55$0.90$1.20$1.75

74LS365 $0.75

74LS373 $2.20

Z80A $5.50

Z80 $4.20

REG. 7805 $0.90

LOOK!

MICROACE/SINCLAIR USERS

SOCKETS LOW PROFILE

14 PIN $0.1016 PIN $0.10

18 PIN $0.1520 PIN $0.15

10V Power Adapter 600ml. $6.90

24 PIN $0.25

40 PIN $0.30

UHF Modulators $9.90

GET YOURSELF A NEW EPSON

MX80 it MX70 PRINTER ANDSAVE A FORTUNE

Price on application

Interface Cards for Apple.Pel, TRS80, and PMC -RS232 Interface Cards notnecessary for parallelFull TRS80

COMP PRO MIXER

. .!_ I Professional

audio mixer

that you can

build yourself

and saveI over $200.

Only $199 forcomplete kit.

I power supplyI $50.00

1 POSTAGEH $20

ACCESSIT AUDIO ADD-ONS

pro'-!'-:,.;

• • • • •

• • • • •

• • • • •

. i

§.li*\

fj.-fHfl

8K FLOATING POINTSUPER ROM PACK

ONLY $35

WITH NEW MANUAL

MICROACE/SINCLAIRVIDEO UPGRADE KIT

Only runs with NEW ROM AOQ

(Smooth screen displayl 0NLY **"

MICROACE/SINCLAIR

16K RAM PLUSEXPANSION BOARD

3 SLOTS WITH EXTRA POWER SUPPLY

16K

$149

4K

$110

LMicrofkeJ

A COMPLETECOMPUTER

A new

generation of

miniature

computers

Kit ONLY $149Post and Packing FREE

Sinclair is a Registered Trademark of Sinclair Research Ltd.

LMicrofkeJ

£bk

Please make checks and money orders payable to MicroAce or phone your order quoting Master Charge, Visa,Diners Club or American Express number for immediate despatch. Add 6% Tax for Shipments inside California.MicroAce, 1348 East Edinger, Santa Ana, California, Zip Code 92705. Telephone: (714) 547 2526

Circle 228 on inquiry card.

BYTE September 1981 369

Circle 328 on inquiry card.

UNBELIEVABLE!

State-of-the-art Single-Board computernow available! Can be used in S-100(Master, Slave, Multi or Single user)or Stand-Alone configurations.

FINALLY, state-of-the-art performance Is avail-able at an affordable price.COMPARE THESE FEATURES:

• ZSOAorZBOB

• 4 TIMERS |ZCTC|

• MR RAM [64KX1 CHIPS)

• 2 SERIAL PORTS |ZSK>|

• 4 PARALLEL PORTS |ZPIO|

• UP TO I6K EPROM (2732)

• NEC FLOPPY DISK CONTROLLER

|UP TO FOUR 8" DOUBLE SIDED/DOUBLE DENSITY DRIVES)

• INTELLIGENT WINCHESTER INTERFACE

• ON-BOARD EPROM BURNER

(DOES NOT REQUIRE 24VJ

FOR THESE SINGLE QUANTITY PRICES:

$895°°

4MZ VERSION (Z80A)

6 MZ VERSION (Z80B|

4 MZ SLAVE PROCESSOR

[NO DISK CONTROLLERS ON SOARD|

6 MZ SLAVE PROCESSOR

(NO DISK CONTROLLERS ONBOARD)

$1,195°°

$795°°

?1,095°°

The S-100 version of this product can act as aMaster processor. Slave processor, or Intelli-gent peripheral controller. Intra-processor com-munication Is achieved through the use of effi-cient, high speed buss transfers using specialhardware/software techniques.We also have what we think Is one of the bestImplementations of a C'P/M BIOS available offthe shelf. The BIOS has the following features:

• All Devices INTERRUPT DRIVEN

• Type Ahead Input/Output Buffers

• Real-Time Clock

• Time Of Day Clock

• Multi-level User Password Support

• Menu Driven Utilities for Format,Disk Copy, etc.

• Unique Configuration Utility Programfor Setting Baud Rates, Changing StepTime, Changing Passwords, etc.

• Cylinder Concept used for Double Sided/Double Density ConfigurationResulting In Increased Performance

CP<M Is ■ (sglalarad Iridsmirk of Digital RaaearchCorporate

Dealer Inquiries Invll

es Invited ttitJUitxtti__

Sierra Data Sciences

i 1300 East Shaw Avenue • Suite 164 • Fresno, California 93710 • (809) 3114-0680 i

ATTENTION GOVERNMENT D PUSERS AND PURCHASERS

We represent many fine micro products and manufacturerson the U.S. Government's GSA Schedule, including

Apple, Cromemco, Micropolisand Seequa Computers

Purchasing from the Schedule will save you the timeconsumed by the bid process. Products shipped throughoutthe United States and world-wide. Visit or write any of ourstores for more information or to receive our catalogue ofproducts represented.

Computers.

the dependable store

257 West Street, Annapolis, MD 21401 - (301) 268-6505

13A Allegheny Avenue, Towson, MD 21204 - (301) 296-0520

9330 Georgia Avenue, Silver Spring, MD 20910 - (301) 588-3748

6671 Backlick Road, Springfield, VA 22150 - (703) 644-5500

Plaza 38, 2442 Route 38, Cherry Hill, NJ 08002 - (609) 779-0023

Callers outside metropolitan areas served by our stores

Please call (301) 268-5801

Career Opportunities Available * An Equal Opportunity1 Employer

ciation, 32 Ainsworth Ave,East Brunswick NJ 08816.

Amethyst UsersGroup In Texas

Amethyst is an expandabletext editor and formatter dis-tributed by Mark of the Uni-corn. Amethyst's commandset is written in BDS C. TheAmethyst Users Group assistsusers in developing exten-sions to Amethyst. Annualmembership is $6, and floppydisks are $6. Contact thegroup at 1633 Royal Crest,#1128, Austin TX 78741,(512) 441-9466.

SorcererUsers Newsletter

Port Fe is a newsletter forExidy Sorcerer users. It in-cludes articles, equipmentreviews, and program list-ings. Subscriptions are $15 inCanada and $23 elsewhere.Contact the Sorcerer UsersGroup Toronto, POB 1173,Station B, Downsview, On-tario, M3H 5V6, Canada.

Club In theHeart off Texas

The Midland Microcom-puter Users Associationmeets at 7 PM on the firstWednesday of the month atthe Sound Machine in Mid-land, Texas. The club's maininterests are exchanging in-formation and assisting newcomputer hobbyists. If youown a microcomputer, youare invited to join, even ifyou don't live in the area.The annual fee is $15, and anewsletter is being workedon. Contact the MidlandMicrocomputer Users Associ-ation, 1024 Andrews Hwy,Midland TX 79701; or con-tact Mark T Cruse, 3609Stanolind, Midland TX79703, (915) 694-4868.■

370 September 1981 © BYTE Publications Inc

Circle 84 on Inquiry card.

Circle 113 on inquiry card.

FULL COLOR

GRAPHICS

The original 256-color imaging system withhigh resolution video FRAME GRABBERfor the S-100 bus. ^srh.

Capture and digitize a video frame in 1 /60 of asecond. Select the best resolution foryour ^application, from 256 to 1280 pixels ^tfrW^'f. i'per TV line. Display your digitized J^'-or computer processed image , .>:',.■■■■■£**with 256 gray levels or 256 ra**1colors on standard ,- t

B&W.NTSCorRGB . [;X"\>

coVor TV monitors. \.A*t ■

_7" Features:

Compact two-boardbasic system

4fiOn512 Computer-generated

l

• Highest possible quality 480x512x8 digital videoimage presently available on the market

• Input capability from TV camera or other sources

• Variety of synchronization choices

• 2 selectable video A/D conversion circuits

• Choice of 1. 2, 4. 8. 16 or 32 bits per pixel

• 32K-byte Image memory on the basic system

• 32, 64, 128 & 256K byte system capacity

• Lightpen Input

• Photographic bigger control Input

• Software selectable system parameters

• Interfaces for TRS-80 and other processors

• Comprehensive line of accessories, monitors andsupport software

SEND FOR FREE CATALOG

S DIGITAL GRAPHIC SYSTEMS

= 935 Industrial Ave., Palo Alto, CA 94303

415/856-2500

Circle 310 on inquiry card.

JANUS #

the language that is basedon the past but looks to theuses of the future:

JANUS is a true compiler for a subset of ADA.ADA is the much awaited U.S. Department ofDefense language. With JANUS, it is availablenow on your CP/M system.

JANUS has such features as:

Separate Compilation

Records with variants

Subranges, Enumerations, and Arrays

Initialized Variables

Integers and Arbitrary Precision Reals

Produces ROMable, Re-entrant 8080 machine code

and much more . . .

JANUS is the face of the future. The structured languagethat you need for efficient programming. This is your chanceto get to the head of the crowd and learn the language thatwill be the language of the 80's.

JANUS requires an 8080/8085 or Z80 CPU, 56K ofmemory, and at least one 8" floppy disk. JANUS is suppliedon a single density 8" floppy. For $250, you get the JANUScompiler, linker, assembler, and owners manual.

FfcS

CP/M is a trademark of Digital Research, Inc.

ADA is a trademark of the U.S. Department of Defense

OFTWARE

speciafcls h stale ofhe art program/ring

P.O. BOX 1512

MADISON, WISCONSIN 53701

THE UNBEATABLE COMBINATION :

'icippkz ^ ATARfA

l/TEAM ELECTRONICS1 (800) 547-2492

16k+ $103948k+ $1089400 $329

(16k)*

800 $749

(16k) ,

w/o BASIC

TOLL FREE NUMBER FOR ORDER DESK ONLY. IN OREGON! CALL 479-8723.REPAIRS, PARTS, AND WARRANTIES CALL (503) 479-4150. SORRY NO C.O.D.'S.MASTERCHARGE AND VISA ADD 3%. WE WILL SHIP U.P.S. FREIGHT COLLECTOR ADD 3% FOR FREIGHT AND INSURANCE TO AVOID C.O.D. CHARGES.ALLOW 10 DAYS FOR PERSONAL CHECKS TO CLEAR. PRICES SUBJECT TOCHANGE WITHOUT NOTICE. PRICES GOOD AT MAIL ORDER DEPARTMENTOF STORE #162 ONLY.

DISK DRIVE W/3.3 CONTROLLER

DISK DRIVE ONLY

SILENTYPE PRINTER W/INTERFACE

GRAPHICS TABLET

APPLESOFT OR INTEGER FIRMWARE

LANGUAGE CARD (PASCAL)

PARALLEL PRINTER CARD

SERIAL PRINTER CARD

CENTRONICS PRINTER INTERFACE CARD

CCS. 7710A

CCS. 7720A

DATA SHIFT ADAPTOR

16K RAM CARD (MICROSOFT]

Z-80CARD (MICROSOFT!

HAYES M1CROMODEM

A.B.T, 10 KEY PAD

M&F1 SUP R TERM

M&R SUP-fl MOD (MODULATOR)

tGK MEMORY EXPANSION

PROGRAMMA JOYSTICK

ATARI

410 PROGRAM RECORDER

810 DISK DRIVE

820PHINTER

822 THERMAL PRINTER

825 80 COLUMN PRINTER

830 MODEM

850 INTERFACE MODULE

852 8K MEMORY EXPANSION

853 1GK MEMORY EXPANSIONBASIC LANGUAGE CARTRIDGEVISICALC IATARII

WE HAVE ATARI GAME CARTRIDGES

499429349629139369129

28y279

4294993G9609

530 N.E. "E" STREET

GRANTS PASS, ORE

97526

HARDWARE

9" B&W MONITOR (SANYO) 159

9" B&W MONITOH (N.E.C.) 169

12" B&W MONITOR (SANYO) 199

12" GREEN MONITOR (SANYO) 259

13" COLOR MONITOR (T.I.I 349

I.D.S. 445G PRINTER 699

I.D.S. 460G PRINTER 1099

I.D.S. 560G PRINTER 1329

EPSON MX-80 PRINTER 479

EPSON CABLE AND INTERFACE 89

CENTRONICS 7371 PRINTER 743

CENTRONICS 779 2 PRINTER 889

N.E.C. SPINWRITER PRINTER 2639

QUME SPRINT PRINTER 2499

TEXAS INST. 99/4 499

APPLE SOFTWARE

VISICALC

VISIDEX

VISIPLOT

VISITERM

VISITREND

D.O.S. TOOL KIT

D.O.S. 3.3 UPDATE

APPLE WRITER

SUP-R TEXT (I

GENERAL BUSINESS CONTROLLER

SOFT TECH PAYROLL

STOCKFILE INVENTORY PROGRAM

APPLE ADVENTURE

20RK

SARGON CHESS

GALAXIAN

HI RES FOOTBALL

COMPUTER QUARTERBACK

MANY OTHER 8USINESS. PERSONAL,

AND GAME SOFTWARE AVAILABLE

NO SALES TAX

./ELECTRONIC

Circle 349 on Inquiry card.

BYTE September 1981 371

Event Queue

September 1981

September-December

Four Seminars from Manage-ment Information Corpora-tion (MIC), various sitesthroughout the US. Theseseminars are designed forbusinesspeople who need anintroduction to system selec-tion and use. For a completeschedule of seminars, fees,and locations, contact CarolBell, c/o MIC, 140 BarclayCtr, Cherry Hill N] 08034,(609) 428-1020.

September 8-10

An Introduction to Micro-computers for the ElectronicData-Processing Profession-al, Las Vegas NV. This courseis designed for electronicdata-processing managers,systems analysts, and engi-neers. Some of the coursetopics are applications formicrocomputers in a largecompany, programming inBASIC, and future develop-ment of the microcomputer.A general knowledge of com-puters is recommended. Fordates and other information,contact Byte Educational Ser-vices, 2412 Second Ave, Se-attle WA 98121, (206)625-1961.

September 9-11

Eurographics '81, TechnicalUniversity, Darmstadt, WestGermany. Almost seventyexhibitors are expected to at-tend this computer-graphicsshow. Detailed informationcan be obtained from Die-bold Deutschland GmbH,Attn: Dr H J Grobe, Feuer-bachstrasse 8, D-6000 Frank-furt/Main, West Germany.

September 9-12

Workshops on Pascal andProgramming Techniques,

University of California Ex-

tension, Santa Clara CA. Anintroduction to Pascal andmodern programming tech-niques and style will be pro-vided in this sequence of fourone-day workshops. The se-quence is structured so thateach workshop is indepen-dent but leads to the next.Fees are $175 for individualcourses and $600 for the four-part sequence. Contact Con-tinuing Education in Engi-neering, University of Cali-fornia Extension, 2223 FultonSt, Berkeley CA 94720, (415)642-4151.

September 10-11

Office Automation Systems,

Holiday Inn, Chicago CityCentre, Chicago IL. Thisseminar will feature discus-sions on office automation.Among the topics to becovered are Ethernet, Xeroxstrategies, and worker accep-tance of office automation.For information, contact Ar-chitecture Technology Cor-poration, POB 24344, Min-neapolis MN 55424, (612)925-2930.

September 10-13

The Second Annual Mid-West Computer Show, Mc-Cormick Place, Chicago IL.This show features office sys-tems, data- and word-pro-cessing equipment, telecom-munications equipment,microcomputers, computergraphics, peripherals, andother related supplies. For in-formation, contact the Na-tional Computer Shows, 824Boylston St, Chestnut HillMA 02167, (617) 739-2000.

September 14-17

Software Info '81, Merchan-dise Mart Expocenter, Chic-ago IL. The conference themeis "Productivity ThroughPackaged Software." FranTarkenton is the keynote

speaker. The president of In-put, Peter Cunningham, willdeliver an address. For moreinformation, contact Soft-ware Info, 1730 N Lynn St,Suite 400, Arlington VA22209, (703) 521-6209.

September 14-17

COMPCON Fall '81, CapitalHilton Hotel, WashingtonDC. The conference theme is"Productivity—An UrgentPriority." This conference isintended to provide a focuson productivity throughoutthe computer industry. Gen-eral inquiries for program in-formation should be ad-dressed to COMPCON Fall'81, POB 639, Silver SpringMD 20901, (301) 589-3386.

September 15-16

Workstations, The Conver-gence of Information Process-ing and Telecommunications,

New York NY. The role ofworkstations for profession-al, managerial, and executiveuse is the focus of this two-day seminar. Speakers willdiscuss the Xerox Star work-station and other new de-signs. For more information,contact Probe Research Inc,POB 251, Millburn NJ 07041,(201) 376-7730 or (212)732-5417.

September 15-17

Wescon/81, Brooks Hall,Municipal Auditorium, andHilton Hotel, San FranciscoCA. Sessions on communica-tions, components and de-vices, computer and micro-processor hardware and soft-ware, office automation, andmemory systems will be pre-sented. Exhibits of computerequipment and related prod-ucts will be featured. ContactElectronic Conventions Inc,Suite 410, 999 N SepulvedaBlvd, El Segundo CA 90245,(213) 772-2965.

September 16-18

Diagnostic Software: Plan-ning and Design, ColonialHilton Inn, Wakefield MA.The Polytechnic Institute ofNew York is cosponsoringthis seminar for design, test,and diagnostic engineers andmanagers. Design examples,lectures, informal sessions,and individual and group di-agnostic-programming ses-sions are part of the course.Tuition is $495. Contact Pro-fessor Donald D French, In-stitute for Advanced Profes-sional Studies, One GatewayCtr, Newton MA 02158,(617) 964-1412.

September 16-18

The Engineer As a Communi-cator, Crystal City Marriott,Arlington VA. This confer-ence is sponsored by the IEEE(Institute of Electrical andElectronics Engineers) Profes-sional Communication Socie-ty. Some of the topics to becovered are communicationstechnology, computers intechnical communications,and information gathering,storage, and retrieval. Con-tact Dr Daniel Rosich, Schoolof Business Administration,University of Connecticut,Stamford CT 06903, (203)322-1673.

September 21-24

Microtest '81, University ofKent, Canterbury, England.This symposium will coverthe testing, maintenance, andreliability of microelectronicsystems from development tofield use. Development sys-tems, emulators, reliable soft-ware and hardware, andhigh-level languages are someof the issues to be discussed.Contact the Symposium Sec-retary, Microtest '81, SERT,57-61 Newington Causeway,London, SEl 6BL, England.

372 September 1981 © BYTE Publications Inc

Circle 317 on inquiry card.

Ultimate STATIC RAM is here!

• Bank Select

• Extended Address

• 8/16 bit Data

$ 295 16KB$465 32KB

Assembled and Tested.

Features: Model 32KUS "Uniselect: 3"

• S-100 Bus - confirms with IEEE-696(S100) specifications.

• Data-8 or 16 bit wide, compatible with 8 bit or new 16 bitmachines.

• Extended Address - 24 bit addressing.

• Bank Select - by ports and bits, compatible with Cromemco, AlphMicro, North Star, and many others.

• Fully Static and low power- current is 0.6A typical with 32K byte.

• Two separate 16K addressing, 32K bank select with windowcapability in any 2K increments, any place within the addressed.

• EPROM, 2716, can be mixed with RAM in any place.

• Has provision to take new CMOS mem chips with battery back-up.

• Will support Z80-Z8000 up to 4Mhz clock, 8086/8088 up to8Mhz.

Other S-100 Boards Available: Z80 based CPU, I/O Memory Interface,16K Static Ram.

Fully socketed, solder masks, gold contacts and guaranteed for one fullyear. Delivery: from stock to 72 hours. Ordering: you may call for MC,Visa or COD orders. (Add $5.00 for C.O.D.) Personal checks OK butM.O. speeds shipping. Allow 7 to 1 5 days to clear personal checksbefore shipping. Undamaged boards can be returned within 10 daysfor full refunds.Illinois residents add bVi% sales tax.

OEM, Dealer pricing available

S.C. Digital

P.O. Box 906 Phone:

Aurora, IL 60507 (312) 897-7749

Convert YourIBM Selectricinto aprinter for

only $599

Driven byany Microor MiniComputer

ESCON

i I PRODUCTS,INC.

12919 Alcosta Boulevard

San Ramon, CA 94583

Call Toll Free:

800-227-2148

MARYMAC INDUSTRIES, INC.

In Texas Orders

Questions & Answers

1-713-392-0747

21969 Katy FreewayKaty (Houston) Texas 77450

To Order1-800-231-3680800-231-3681

SAVE BIG DOLLARS ON ALL TRS-80 HARDWARE & SOFTWARE

TRS-80 BY RADIO SHACK. Brand new in cartons delivered. Save state sales tax.Texas residents add only5% sales tax. Open Mon.-Sat. 9-6. We pay freight and insurance. Come by and see us. Call us for a refer-ence in or near your city. Ref: Farmers State Bank, Brookshire, Texas.

WE OFFER ONREQUEST

Federal Express (Overnight Delivery)

Houston IntercontinentalAirport Delivery (Same Day)

U.P.S. BLUE (Every Day)

References from people who havebought computers from us probablyin your city

Telex 77-4132 (FleksHou)

' TRS-80 is a Registered Trademark of Tandy Corp

ED McMANUS

00

00

In atock TRS-80 ModelII and III

No Tax on Out of Texas Shipments!

10% 15%

OR MORE

We Specialize In Overseas Shipments

Telex 77-4132 (FleksHou)

WE ALWAYSOFFER

0 NO extra charge for Master Card

or Visa0 We use Direct Freight Lines. No

long waits.

0 We always pay the freight andinsurance

0 Toll free order number

0 Our capability to go to the giantTRS-80 Computer warehouse 5hours away, in Ft. Worth, Texas,to keep you in stock.

JOE McMANUS

Circle 204 on inquiry card.

BYTE September 1981 373

&^<

,^>"

«*i7 SOFTWARE

ULTIMATE SOFTWARE PLAN

We'll match any advertised priceon any item that we carry. And ifyou find a lower price on what youbought within 30 days of buyingit, just show us the ad and we'llrefund the difference.It's that simple.

Combine our price protectionwith the availability of full profes-sional support and our automaticupdate service and you have theUltimate Software Plan.

It's a convenient, uncomplicated,logical way to get your software.

Its

ARTIFICIAL INTELLIGENCE

Medical(PAS-3) $849/$40

Dental (PAS-3) $849/$40

ASYST DESIGN

Prof Time Billing $549/$40

^ General Subroutine. . ,$269/$40s Application Utilities.... $439/$40

COMPLETE BUS. SYSTEMS

Creator $269/$25

Reporter $169/$20

Both $399/$45

COMPUTER CONTROL

Fabs(B-tree) $159/$20

UltraSort II $159/$25

COMPUTER PATHWAYS

Pearl (level 1) $ 99/$25

Pearl (level 2) $299/$40

Pearl (level 3) $549/$50

DIGITAL RESEARCH

CP/M 2.2

NorthStar $149/$25

TRS-80 Model II (P+T)$159/$35

Micropolis $169/$25

Cromemco $189/$25

PL/l-80 $459/$35

^BT-80 $179/$30

Mac $ 85/S15

Sid $ 65/$15

2-Sid $ 90/$15

Tex $ 90/S15

DeSoool $ 50/S10

D.M.A.

Ascom $149/$15

DMA-DOS $179/$35

CBS $369/$45

Formula $539/$45

GRAHAM-DORIAN

General Ledger $729/$40

Acct Receivable $729/$40

Acct Payable $729/$40

Job Costing $729/$40

Payroll II $729/$40

Inventory II $729/$40

Payroll $493/$40

Inventory $493/$40

Cash Register $493/$40

Apartment Mgt $493/$40

Surveying $729/$40

Medical $729/$40

Dental $729/$40

MICRO-AP

S-Basic $269/$25

Selector IV $469/$35

MICRO DATA BASE SYSTEMS

HDBS $269/$35

MDBS $795/$40

^DRSorQRSorRTL. . .$269/$ 10

MDBS PKG $1295/$60

MICROPRO

WordStar $319/$60

Customization Notes...$ 89/$na

Mail-Merge $109/$25

WordStar/Mail-Merge. $419/$85

DataStar $249/$60

WordMaster $119/$40

SuperSortl $199/$40

\S (New items or new prices)

CP/M users: specify disk systems and formats. Most formats available.

MICROSOFT

Basic-80 $289/$30

Basic Compiler $329/$30

Fortran-80 $349/$30

Cobol-80 $574/$30

M-Sort $124/$30

Macro-80 $144/$20

Edit-80 $ 84/$20

MuSimp/MuMath $224/$25

MuLisp-80 $174/$20

"PASCAL"

Pascal/MT+ $429/$30

Pascal/Z $349/$30

>/ Pascal/UCSD 4.0 $429/$50

• Pascal/M $189/$20

ORGANIC SOFTWARE

^TextWriter III $111/$25

DateBookll $269/$25

^ Milestone $269/$30

OSBORNE

General Ledger $ 59/$20

Acct Rec/Acct Pay. . . .$ 59/$20

Payroll w/Cost $ 59/$20

All 3 $129/$60

All 3 +CBASIC-2 $199/$75

PEACHTREE'

General Ledger $399/$40

Acct Receivable $399/$40

Acct Payable $399/$40

Payroll $399/$40

Inventory $399/$40

Surveyor $399/$40

Property Mgt $799'/$40

CPA Client Write-up. . $799/$40Mailing Address $349/$40

SOFTWARE WORKS

Adapt (CDOS to CP/M). $ 69/$naRatfor $ 86/$na

SOHO GROUP

MatchMaker $ 97/$20

Worksheet $177/$20

STRUCTURED SYSTEMS

GLorARorAPorPay .$599/$40

Inventory Control $599/$40

Analyst ;$199/$25

Letteright $179/$25

QSort $ 89/$20

SUPERSOFT

Diagnostic I $ 49/$20

Diagnostic II $ 84/$20

Disk Doctor $ 84/$20

s Forth (8080 or Z80). ...$149/$30

Fortran $219/$30

Fortran w/Ratfor $289/$35

Other less 10%

TCS

GLorARorAPorPay. $ 79/$25

All 4 $269/$99

UNICORN

^Mince $149/$25

^Scribble $149/$25

v'Both $249/$50

Amethyst $299/$75

WHITESMITHS

"C" Compiler $600/$30

Pascal (incl "C") $850/$45

"DATA BASE"

FMS-80 $649/$45

dBASE II $629/$50

Condor $599/530

Condor II $899/$50

Access/80 $749/$50

"WORD PROCESSING

Word Search

SpellGuard

VTS/80

Magic Wand

Spell Binder

"OTHER GOODIES

The Last One

SuperCalc

Target

BSTAM

BSTMS

TinyX"

Tiny "C" Compiler .

CBASIC-2

Nevada Cobol

MicroStat

Vedit

MiniModel

StatPak

Micro B +

Raid

String/80

String/80 (source)..

$179/$50$229/$25$259/$65$289/$45$349/$45

$549/$95$269/$50$189/$30$149/$15$149/$15$ 89/$50$229/$50$ 98/S20$129/$25$224/$25$105/515$449/$50$449/$40$229/$20$224/$35$ 84/$20$279/$na

INFO UNLIMITED

EasyWriter $224

Datadex $349

Other less 15%

MICROSOFT

Softcard (2-80 CP/M). $259

Fortran $179

Cobol $499

MICROPRO

Wordstar $269

MailMerge $ 99

Wordstar/MailMerge . $349SuperSortl $159

PERSONAL SOFTWARE

Visicalc3.3 $159

CCA Data Mgr $ 84

Desktop/Plan II $159

Visiterm $129

Visidex $159

Visiplot $149

Visitrend/Visiplot $229

Zork $ 34

PEACHTREE*

General Ledger $224/$40

Acct Receivable $224/$40

Acct Payable $224/$40

Payroll $224/$40

Inventory $224/$40

"OTHER GOODIES"

dBASE II $329/$50

\S VU #3(usew/Visicalc).$ 79

Super-Text II $127

Data Factory $129

DB Master $184

OEM (complete

accting) $399

Charles Mann less 15%

STC less 15%

ORDERS ONLY-CALL TOLL FREE VISA • MASTERCHARGE

1-800-854-2003 ext. 823 • Calif. 1-800-522-1500 ext. 823

Overseas —add $10 plus additional postage • Add $2.50 postage and handling per each item • California

residents add 6% sales tax • Allow 2 weeks on checks. CO. D. ok • Prices subject to change without notice.

All items subject to availability • ® — Mfgs. Trademark.

THE DISCOUNT SOFTWARE GROUP

6520 Selma Ave. Suite 309 • Los Angeles, Ca. 90028 • (213) 666-7677

Int'l TELEX 499-0032 BVHL Attn: DiscSoft • USA TELEX 194-634 BVHL Attn: DiscSoft •

TWX 910-321-3597 BVHL Attn: DiscSoft

September 24-25

Microprocessors: Hardware,Software, and Applications,

Worcester Polytechnic Insti-tute, Worcester MA. Amongthe courses to be offered arehardware and software ba-sics, selection and evaluationof microprocessors, memoryand input/output systems,multiprocessor systems, real-time-system design, and de-bugging and circuit testing.For more information, con-tact Ginny Bazarian, c/oContinuing Education, Wor-cester Polytechnic Institute,Worcester MA 01609, (617)753-1411, ext 517.

September 24-27

The Second Annual Mid-At-lantic Computer Show,

Washington Armory, Wash-ington DC. For details, seeSeptember 10-13.

September 30-October 2

Data and Telecommunica-tions Expo '81, Rhein-Main-Halle, Wiesbaden, West Ger-many. This exhibition andconference will cover datacommunications, distributeddata processing, and telecom-munications networks. Fu-ture telecommunications de-velopments, internationalnetwork management, andgraphics will also be dis-cussed. Contact Cahners Ex-position Group, 222 WAdams St, Chicago IL 60606,(312) 263-4866. In Europe,contact Kiver Communica-tions S A, U K Branch Of-fice, Millbank House,171/185 Ewell Rd, Surbiton,Surrey, KT6 6AX, England.

October 1981

October-November

Workshops from VirginiaPolytech, Virginia Polytech-nic Institute and State Uni-versity, Blacksburg VA.Workshops on microcomput-er-design interfacing and pro-gramming, digital electronics

374 September 1981 © BYTE Publications Inc

Circle 120 on Inquiry card.

Circle 373 on inquiry card.

Circle 244 on inquiry card.

THE BIGGEST NAME IN LITTLE COMPUTERS*

TRS-80 Model II—Your Best BuyIn a Business Microcomputer

on

TRS-80 computers,software and peripherals

Similar values on all merchandiseCALL COLLECT:

915-283-2920

Van Horn Office Supply

701 W. Broadway -- P O Box 1060Van Horn, Texas 79855

DEALER G055 ■■■

Form F48 ProvidedStandard Warranty on Merchandise

THE NA TIONWIDE SUPERMARKET OF SOUND**

c©

o

0

oo

ooo

0

oooooo

oo

o

o

BUY COMPUTERSBY MAIL ORDERAND SAVE 16%

APPLE HARDWARE

48K (SPECIAL) $1,125.00

Disk with Controller $ 540.00Disk $ 440.00

Pascal $ 445.00

Graphics Tablet $ 655.00

Versawriter Digitizer System

$ 215.00

ATARI 800 16K $ 775.00

PRINTERS

Tl Basic Serial $1,495.00

Epson MX-80 CALL

Centronics 737 Parallel

$ 719.00IDS 560 $1,395.00

CR0MEMC0 COMPUTERS ■ CALLINTERSYSTEM COMPUTERS ■ CALL

TERMINALSZenith Z 19Soroc IQ12Q

Televideo 950Televideo 920CTelevideo 912CADDS Viewpoint

789.00729.00989.00759.00729.00589.00

SOFTWARE

Superbrain Double Density 64K

$2,650.00Quad Density 64K $2,977.00

NORTHSTAR

Horizon-2-64 QD

$3,350.00

VERBATIM & MEMOREX

5%" $ 27.50

MONITORS

Leedex 12" B&W12" GP

$ 138.00$ 152.00

Send certified check (regular checks require 2 weeks to clear) orcharge to VISA or Masrer Charge Customer pays shipping.

MIRO COMPUTERS, INC.

27 Long Meadow Place South Setauket, L.I., N.Y. 11720(516) 423-7955 call mon.-sat., ioam-apm

OOO

ooooooooooooooo

I

THE SYSTEM INTEGRATORS

• Are you tired of installing systems that cannot expand to meet your needs?

• Are you tired of the problems of interfacing multi-vendor systems?

• Are you tired of receiving new systems that don't work and waitingdays or weeks for replacements?

• Are you tired of making a computer investment and not receiving theprofessional help and support you deserve?

If you have answered yes to any one of the abovequestions, you need a change!

We have combined the most flexiblemicrocomputer on the market (IthacaDooto%'sfei]fl[]S') with reliable, large capacity floppyand hard disk storage systems from Qume,Memorex, Shugart and Priam, along with themost dependable CRTs and printers availabletoday. Using the industry standard CP/M*Operating System, our turnkey systems aredelivered to you fully assembled, tested andburned in.

PROVEN RELIABILITY — Our turnkey systems havebeen performing daily for over a year in highvolume point-of-sale operations throughout thecountry.

SOFTWARE AVAILABILITY — A wide variety ofapplication software packages are ready forCP/M systems. Our library contains many ofthese systems, and it is expanding daily.

CUSTOM DESIGN — P.O.S. Terminals, hardware andsoftware interfaces between Ithaca Intersystemsand other specialized I/O devices.

COMPETITIVE PRICES — Floppy-based systems startat 57,950, 10MB hard-disk systems with floppyback-up start at $10,650. These are true turnkeysystem prices that include CRT. printer, anddouble-sided/density floppies, tested and burned in.

TALK TO THE PEOPLE WHO SELL CUSTOMER SATISFACTION

Specialized Business Systems

5306 S. Bannock, Littleton, CO 80120(303) 797-8709

'"Trademark of Ithaca Intersystems, Inc.*CP/M is a Registered Trademark of DigitalResearch.

^

Circle 335 on inquiry card.

BYTE September 1981 375

IF YOU WANT LOWER PRICES

AND QUICKER SERVICE. . . YOU WANT MICROMAIL.

TELE VIDEO 910

$599.00

912 $699.00

920 $749.00

950 $995.00

Model 912 C shown

DIABLO 630

$1959.00

1640 RO $2269.00

1640 KSR $2499.00

1650 RO $2599.00

1650 KSR $2599.00

Model 630 shown

ANADEX

DP 8000

$775.00

DEC

LA34DA

$969.00

Shown with optional forms tractor and keypad.

ANADEX

DP 9500.DP 9501.DP 9000.DP 9001.

$1299.00$1299.00$1199.00$1199.00

TEXAS INSTRUMENTS

810/2 $1549.00

810/2 PKG (U/l vfc cp) $1679.00

TELETYPE

43 PF(TTL) $975.00

SOROC

DEC

161120...IQ. 140...IQ 135 ...

C. ITOH

.. $689.00 VT 100 $1650.00

.$1099.00 DEC LA 34AA $ 1050.00

.. $849.00

NEC

CIT 101.

5510 $2395.00

. $1625.00 5530 $2395.00

To Order: Send check to MICROMAIL, P.O. Box 3297. Santa Ana. CA 92703. Personal or company checksrequire two weeks lo clear. Visa/MasterCard accepted. COD. requires a 15% deposit. Handling: Add 3% toorders less than S750. 2% lo orders S751 - S2.000.1% lo orders over S2.000 NOTE: Handling charges arewaived on orders prepaid in advance by check. Shipping: We ship FREIGHT COLLECT via UPS or MotorFreight. Air and Express delivery is available -. .. .. _,„.

Prices subject to change without notice.

i:in.CR[Jllflfl.L.,

P.O. Box 3297Santa Ana, CA 92703Phone: 714/731-4338TWX: 910 5951146

for automation and instru-mentation, and sessions usingthe TRS-80 are part of thecurriculum. All workshopsare hands-on with partici-pants designing and testingconcepts on the actual hard-ware. Contact Dr LindyLeffel, Virginia PolytechnicInstitute and State Universi-ty, Blacksburg VA 24061,(703) 961-5241.

October 7-9

Institute on Microcomputersfor Instruction and Researchin Higher Education, Jane SMcKimmon Center, NorthCarolina State University,Raleigh NC. The institute isdesigned to help high-leveleducators learn about themicrocomputer and the role itcan play in higher education.Contact Joyce Currie, c/oNorth Carolina EducationalComputing Service, POB12035, Research TrianglePark NC 27709, (919)549-0671.

October 7-21

The 1981 Far East ComputerTour, Japan, South Korea,Taiwan, and Hong Kong.This tour group will visitvarious computer-relatedconferences and exhibitionsthroughout the Far East.Transportation for this three-week tour, plus shows,meals, and other items are in-cluded in trip packages,ranging in price from $2290to $3095. For more informa-tion, contact Terry Butler,Commerce Tours Interna-tional Inc, 870 Market St,Suite 742-744, San FranciscoCA 94102, (415) 433-3072.

October 9-11

Rhode Island Computer andVideo Electronics Show, Pro-vidence Civic Center, Provi-dence RI. This is the first ma-jor computer exhibition andshow to be held in Rhode Is-land. Exhibitors and salesteams will present the latest

376 September 1981 © BYTE Publications Inc

Circle 234 on inquiry card.

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EVTE

the small systems journal

Circle 187 on inquiry card.

Z-80 and 8086 FORTH

Z-80® FORTH—a complete program development system. Usesstandard CP/M® compatible random access disk files for screenstorage. Package includes: interpreter/compiler with virtual mem-ory management, line editor, screen editor, Z-80 Assembler, de-compiler, utilities, demonstration programs, and 80 page usermanual. System requirements: Z-80 microcomputer, 48 kbytesRAM, CP/M 2.2 or MP/M® 1.1. $50.00

Z-80 FORTH WITH NAUTILUS SYSTEMS CROSS-COMPILER.

Extend/modify the FORTH runtime system, recompile on a hostcomputer for a different target computer, generate headerlesscode, generate ROMable code with initialized variables. Supportsforward referencing to any word or label. Produces load map andlist of unresolved symbols. 107 page manual. System require-ments as for Z-80 FORTH above. $200.00

8086 FORTH with line editor, screen editor, assembler, andutilities. Uses standard CP/M compatible random access files forscreen storage. Requires 8086 or 8088 microcomputer, 64 kbytesRAM, and CP/M-86 operating system. $100.00

MACHINE TEST PROGRAM PACKAGE for Z-80 systems. Includesmemory, floppy disk, printer, and terminal tests with all sourcecode. Requires CP/M 2.2. $50.00

All software distributed on eight-inch soft sectored single densitydiskettes. Prices Include shipping by first class or UPS within USAor Canada. COD charges extra. Purchase orders accepted at ourdiscretion. (CP/M and MP/M are registered trademarks of DigitalResearch, Inc. Z-80 is a registered trademark of Zilog, Inc.)

Laboratory Microsystems

4147 Beethoven Street

Los Angeles, CA 90066

(213)390-9292

A REFURBISHED DAISY WHEEL TERMINALFOR PERSONAL COMPUTER USERS AND SMALL BUSINESSES.

Now you can have letter-quality printingand professional features for just $1,495?

AJ daisy wheel printer terminals are renowned forexceptional performance, high reliability, and applicationsversatility. Now you can have all this for only $1,495* in ourspecial limited offer.

• 30 cps letter-quality printing

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• Full ASCII keyboard withnumeric pad

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Call your nearest AJ regionali office for details: San Jose, CA

(408) 946-2900; Rosemont, IL(312)671-7155; Hackensack,NJ (201) 488-2525. Or checkthe phone book for the numberof your local AJ sales/serviceoffice.

"Price excludes options and is subject tochange without notice. Model shown includescertain options. Offer available only in thecontiguous U.S.

ANDERSON

JACOB5DN

Circle 23 on Inquiry card.

BYTE September 1981 377

System Log

3 so AM - 5&L&H* &j£tt&k. L

D//?&A/csr/cs Vn. v

£/HU<* st£ZL/dJU<t QamL

sUf4s&#t ^fa<Jt art ^C*tt^%

Diagnostic II builds upon the highly acclaimed Diagnostics I. It will testeach of the five areas of your system:

Memory Terminal Printer CPU Disk

Every test is expanded.

Every test is "submit"-able. A "submit" file is included in the package which"chains" together the programs in Diagnostics II, achieving an effectiveacceptance test. All output can be directed to a log file for unattended operation,for example over night testing. Terminal test is now generalized for most crtterminals. A quick-test has been added for quick verification of the workingof the system.

The memory test is the best one we have encountered. It has new features,including:

• default to the size of the CP/M Transient Program Area (TPA)

• printout of a graphic memory map • burn in test

• bank selection option • memory speed testDiagnostics-ll still includes the only CPU test for 8080/8085/Z80.

A Spinwriter/Diablo/Qume test has been added, which tests for the positioningand control features of the Spinwriter/Diablo/Qume as well as its ASCIIprinting features. (Serial Interface only)

And, as with all SuperSoft products, a complete online HELPsystem and user manual is included.

Price: $100.00 (manual only): $15.00

Requires: 32K CP/M

CP/M Formats: 8" soft sectored, 5" Northstar, 5" MicropolisMod II, Vector MZ, Superbrain DD/QD

All Orders and General Information:

SUPERSOFT ASSOCIATES

P.O. BOX 1628

CHAMPAIGN, IL 61820

(217)359-2112

Technical Hot Line: (217) 359-2691

(answered only when technician is available)

CP/M REGISTERED TRADEMARK DIGTAL RESEARCH

SuperSoft

First in Software Technology

in computers and video prod-ucts for business, industry,government, education, andhome use. Contact New LeafProductions, Suite 335, 77Ives St, Providence RI 02906,(617) 679-0089.

October 12-15

Information Management Ex-position and Conference:INFO 81, Coliseum, NewYork NY. Discussions on pre-packaged, customized pre-packaged, and custom-de-signed software will comple-ment hardware and softwareexhibits. For more informa-tion, contact Clapp & PoliakInc, 245 Park Ave, New YorkNY 10167, (212) 661-8410.

October 13-15

Understanding and UsingComputer Graphics, NewYork NY. Headed by CarlMachover, this two-day sem-inar examines the state of theart in graphic systems. Thefocus will be on hardware,software, and applications.Contact Bob Sanzo, c/o Frost& Sullivan Inc, 106 Fulton St,New York NY 10038, (212)233-1080.

October 15-18

The Third Annual NortheastComputer Show and OfficeEquipment Exposition,

Hynes Auditorium, BostonMA. This show will featurehardware, software, and sup-plies for business, education,government, home, and of-fice use. Office systems andequipment will also beshown. Contact NationalComputer Shows, 824 Boyl-ston St, Chestnut Hill MA02167, (617) 739-2000.

October 16-23

The Fourteenth BrazilianComputer Conference andExhibit, Anhembi Conven-tion and Exhibit Halls, SaoPaulo, Brazil. This con-ference will feature technicaltalks, conference tutorials,

378 September 1981 © BYTE Publications Inc

BvIE Back Issues for sale

The following Issues are available:

1976: July

1977: April thru December except October

1978: February thru December except November

1979: January thru December except March1980: January, March thru August, and December

1981: February to current issue except MarchCover price for each issue through August 1977 is $1.75

Domestic: $2.75 Canada and Mexico; $3.75 Foreign.

September 1977 through October 1979 issues are $2.50

Domestic: $3.50 Canada and Mexico; $4.50 Foreign.

November 1979 to current is $3.00 Domestic; $4.00 Canada

and Mexico; $5.00 Foreign.

Send requests with payment to:

BYTE Magazine

70 Main St, Peterborough NH 03458

Attn: Back Issues

Circle 56 on inquiry card.

SURPLUS BUYS of the YEAR!!

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MODEL 429 POWER SUPPLY ±24VDC @ 6 amps, 5V @ 6 amps. Required lorboth the 44A and 43 drives (above) '75.00m.

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* SELECTRIC-II Typewriter/Printer R0*SELECTR1C-II PRINTER

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The Paper Tractor™ turns your tractor feedprinter into a friction feed printing system.Inexpensively.

With The Paper Tractor you can abandondull continuous form stock and move into newrealms of high quality personalized writingpaper. Without costly hardware modifications.

This revolutionary product acts as a carrier,protecting and guiding any standard letter or

legal size paper through the printing area. Anypaper. Bond, parchment, onionskin, vellum,NCR, manuscript paper (sheet music). Evenyour company or personal letterhead.

The Paper Tractor is a unique solution to therestrictive nature of the tractor feed printer.

•Compatible with Matrix, Impact, Daisywheel and InkEjection printheads.

•Fits front, back and dual tractor paper feeds.

• Designed with self-aligning feed system.

•Positions letter or legal size paper automatically with anedge-protecting guide.

•Designed for use with forward/reverse plotting printers.

•Proven with all major manufacturer's printers, includingEpson, Tiger, Tl, GP-80M, DEC-Writer, Commodore,Centronics, Radio Shack VVI VII, Beehive, Vista, Grafix-Plus, Axiom, Coment, Hl-Q, DIP, C-ITOH, Cromemco,Okidata and many more.

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ATTENTION GOVERNMENT D PUSERS AND PURCHASERS

We represent many fine micro products and manufacturerson the U.S. Government's GSA Schedule, including

Apple, Cromemco, Micropolisand Seequa Computers

Purchasing from the Schedule will save you the timeconsumed by the bid process. Products shipped throughoutthe United States and world-wide. Visit or write any of ourstores for more information or to receive our catalogue ofproducts represented.

Computers,

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roundtable discussions, andspecial events. Computer-aided design and manufac-ture in developing countrieswill also be discussed. Con-tact Sucesu Sao Paulo, RuaTabapua, 627-1.° andar,04533, Sa3 Paulo, S P, Brazil.

October 18-20

The Annual Conference ofthe New York State Associa-tion for Educational DataSystems (NYSAEDS), Syra-cuse NY. NYAEDS is madeup of people with an interestin computers and education.Workshops on the education-al uses of microcomputersoftware will be held. Con-tact Don Ross, Ardsley HighSchool, Ardsley NY 10502.

October 19-23

Systems '81, Munich, WestGermany. Computer systemsand their applications will befeatured. Additional infor-mation is available from Kail-man Associates, 30 JournalSq, Jersey City NJ 07306,(201) 653-3304.

October 20-22

The Annual Government-Industry Data Exchange Pro-gram (GIDEP) Workshop,

Rickey's Hyatt House, PaloAlto CA. The GIDEP annualworkshop is open to anyoneinterested in the exchange oftechnical information relatingto engineering, failure ex-perience, reliability, andmaintainability. Contact theOfficer-in-Charge, GIDEPOperations Center, CoronaCA 91720.

October 20-22

Computerized Office Equip-ment Expo, Southwest, As-trohall, Houston TX. Ap-proximately 100 exhibitorswill present office equipmentand supplies, including word-processing systems, at thisshow. Contact Cahners Ex-position Group, 222 WAdams St, Chicago IL 60606,(312) 263-4866.

380 September 1981 © BYTE Publications Inc

Circle 188 on inquiry card.

Event Oueue

October 21-24

COMPUTA 81, World TradeCenter, Singapore. This in-ternational show attracts pro-fessionals and buyers fromHong Kong, India, and SriLanka. Additional informa-tion can be obtained fromKallman Associates, 30 Jour-nal Sq, Jersey City NJ 07306,(201) 653-3304.

October 24-25

The Second Annual NewJersey Microcomputer Showand Fleamarket, Holiday Inn(north) Convention Center,Newark International Air-port, Newark NJ. This showwill feature 75 commercialexhibitors and more than 100vendors. User-group meet-ings will be held. Registrationis $5 for both days. ContactKengore Corporation, 3001Rt 27, Franklin Park NJ08823, (201) 297-2526.

October 25-30

The Forty-Fourth AnnualMeeting of the American As-sociation of Information So-cieties (ASIS), WashingtonHilton Hotel, WashingtonDC. The theme for this meet-ing is 'The Information Com-munity: An Alliance for Pro-gress." Among the topics tobe addressed are informationand creativity, informationand society, and overcomingthe barriers between informa-tion sciences. Contact ASIS,1010 Sixteenth St, NW,Washington DC 20036, (202)659-3644.

October 27-29

Computer Graphics 81, Re-gent Centre Hotel, London,England. Some of the topicsto be covered are graphicssystems: hardware and soft-ware; animation; image pro-cessing; simulation; and busi-ness and home graphics. Anequipment exhibition willalso be presented. For moreinformation, contact OnlineConferences Ltd, ArgyleHouse, Northwood Hills,

Middlesex,England.

HA6 ITS,

October 29-November 1

Southeast Computer Showand Office Equipment Expo-sition, Atlanta Civic Center,Atlanta GA. For details, seeOctober 15-18.

October 31-November 1

Computers in AmbulatoryMedicine, Washington Shera-ton, Washington DC. TheSociety for Advanced Medi-cal Systems and the Societyfor Computer Medicine aresponsoring this conference.Basic and advanced tutorialson the fundamentals of medi-cal computing will be fea-tured along with technicalsessions and presentations ofpapers. Fees are $115 for So-ciety members and $165 fornonmembers. Contact SCM,9650 Rockville Pike,Bethesda MD 20014, (301)530-7120.

October 31-November 2Annual Meeting of theAmerican Society for Cyber-netics, Washington HiltonHotel, Washington DC. Thetheme for this meeting is 'TheNew Cybernetics." A goal ofthe meeting will be to rede-fine the field of cyberneticsand to provide a focus for theresearch efforts of the Socie-ty. Among the topics to bediscussed are robotics, pro-blem solving, patternrecognition, remote sensing,and communication net-works. Contact Dr LaurenceD Richards, Department ofAdministrative Science, Col-by College, Waterville ME04901, (207) 873-1131, ext587.

November 1981

November 1-4

DPMA San Francisco '81,San Francisco Civic Centerand Brooks Hall, San Fran-cisco CA. This is DPMA's(Data Processing Manage-ment Association's) thirtieth

September 1981 © BYTE Publications Inc 381

Event Queue

annual conference and busi-ness exposition. Contact theconference coordinator,DPMA, 505 Busse Hwy, ParkRidge IL 60068, (312)825-8124.

November 5

Invitational Computer Con-ference, Amsterdam, Nether-lands. The Invitational Com-puter Conference is a one-day computer show designedfor quantity buyers. Exhibitsand seminars are featured.For details, contact B JJohnson & Associates Inc,2503 Eastbluff Dr, Suite 203,Newport Beach CA 92660,(714) 644-6037.

November 8-10

The Twelfth ACM NorthAmerican Computer ChessChampionship, BonaventureHotel, Los Angeles CA. Afour-round, Swiss-style tour-nament is planned for thisyear's championship compe-tition. In addition, a round-robin blitz tournament willbe held. Games in this eventproceed at a rate of 5 secondsper move. Belle, the currentworld champion. Chaos,Duchess, Nuchess, and L'Ex-centrique are among the pro-grams being entered. Formore information, contact

Professor Monroe Newborn,School of Computer Science,McGill University, 805 Sher-brooke St West, Montreal,Quebec H3A 2K6, Canada.

November 9-10

Software Fair, Stouffers' Riv-erfront Towers, St LouisMO. This show is made up ofsoftware exhibitions fromcompanies whose packagesare in current use by mem-bers of the Southern and Na-tional Industrial DistributorsAssociation. Distributorswho are not members ofthese organizations can alsoexhibit their wares. ContactDon White or Tony Carroll,1900 Arch St, PhiladelphiaPA 19103, (215) 564-3484.

November 9-11

ACM '81, Bonaventure Ho-tel, Los Angeles CA. Thismeeting will feature paneldiscussions on computers,software products in the1980s, tutorials on computer-aided design, and a survey onthe impact of robots on em-ployment. Ray Bradbury andDr Simon Ramo will speak.Computer exhibits and theNorth American ComputerChess Tournament will alsobe held. Contact ACM '81,POB 24059, Village Station,

Los Angeles CA 90024, (213)536-9735.

November 10-12

Midcon/81 Show and Con-vention, O'Hare ExpositionCenter and Hyatt RegencyO'Hare, Chicago IL. Talks onmicrocomputers, energy,memory, communications,and consumer electronics willhighlight this show. ContactElectronic Conventions Inc,999 N Sepulveda Blvd, ElSegundo CA 90245, (800)421-6816; in California (213)772-2965.

November 12

Invitational Computer Con-ference, Paris, France. For de-tails, see November 5.

November 16-19

The Canadian ComputerShow and Conference, Inter-national Centre of Com-merce, Mississauga, OntarioCanada. For details, contactReg Leckie, Industrial TradeShows of Canada, 36 But-terick Rd, Toronto, Ontario,M8W 3Z8, Canada, (416)252-7791.

November 17

Invitational ComputerConference, Milan, Italy. Fordetails, see November 5.

November 17-19

Understanding and UsingComputer Graphics, AtlantaGA. For details, see October13-15.

November 19-20

Western Educational Com-puter Conference, San Fran-cisco CA. Many of the com-puter-related talks at thisconference will cover areas ofinterest to college instructorsand administrators. For de-tails, contact Ron P Langley,Data Processing Services,California State University-Long Beach, 1250 BellflowerBlvd, Long Beach CA 90840.

November 29-December 1

National Telecommunica-tions Conference, New Or-leans LA. This event is spon-sored by the IEEE (Institute ofElectrical and Electronics En-gineers) and the New Orleanschapter of the Communica-tions Society ConferenceBoard. Some of the papers tobe presented will discusscommunications electronics,including software, termi-nals, theory, and data andcomputer communications.Contact G Allan Ledbetter,South Central Bell, 365 CanalSt, Rm 1360, New OrleansLA 70140, (504) 528-7350. ■

WIREMASTER

A COMPILER FOR HARDWARE

• WIREMASTER is a software lool to aid- in the design,layout, and construction ol electronic hardware. It isintended primarily for wire wrap, though it is also highlyuseful in the layout , error-checking, and trouble-shootingof PC boards.

• Inpuls are easily derived directly from the schematicdiagram and fed to WIREMASTER in a CP/M* text tile.Outputs include a network map that graphically showsall pins and wires, a wire list sorted by lengths andlevels, a parts list, wrap count and continuity checklists.plus signal and pin cross-reterences.

• The resulting information is then used for PC boardlayouts, error-checking, wiring, component-stuffing,and system-debugging. This forms a complete andeasily updated documentation package. Although it runson small computers. WIREMASTER can handle large projects.

• WlREMASTER.runs on any Z80t CP/M system of 47Kor larger, including TRS-aOt Model II and Apple via 5oftCard§.

Complete Package — $125; Manual only — $10

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382 September 1981 © BYTE Publications Inc

Software Received

This is a list of software packages that have been received byBYTE Publications during the past month. The list is correct to thebest of our knowledge, but it is not meant to be a full descriptionof the product or the forms in which the product is available. Inparticular, some packages may be sold for several machines or inboth cassette and floppy-disk format; the product listed here isthe version received by BYTE Publications.

This is an all-inclusive list that makes no comment on the qualityor usefulness of the software listed. We regret that we cannotreview every software package we receive. Instead, this list ismeant to be a monthly acknowledgment of these packages andthe companies that sent them. All software received is consideredto be on loan to BYTE and is returned to the manufacturer after aset period of time. Companies sending software packages shouldbe sure to include the list price of the packages and (where appro-priate) the alternate forms in which they are available.

Apple

Desktop Plan II, for devel-opment and analysis of busi-ness plans for the Apple II.Floppy disk, $199.95. Person-al Software, 1330 BordeauxDr, Sunnyvale CA 94086.

NORAD, a graphics ar-cade game for the Apple IIand III. Floppy disk, $27.50.Western MicroData Enter-prises Ltd, POB G 33, PostalStation G, Calgary, Alberta,T3A 2G1, Canada.

Robotwar, a graphics gameusing programmable robotsfor the Apple II. Floppy disk,$39.95. Muse, 330 N CharlesSt, Baltimore MD 21201.

Time Manager, a personal-information and organizationsystem for the Apple II. Flop-py disk, $149.95. Image Com-puter Products Inc, 615Academy Dr, Northbrook IL60062.

VisiCalc, the electronicspreadsheet for the Apple II.Floppy disk, $199.95. Person-al Software, (see above ad-dress).

VisiDex, a data-base man-agement system for the AppleII. Floppy disk, $199.95. Per-sonal Software, (see aboveaddress).

VisiPlot, a graph-plottingsystem for the Apple II. Flop-py disk, $179.95. PersonalSoftware, (see above address).

VisiTrend and VisiPlot, autility program that analyzestrends of graphs from Visi-Plot for the Apple II. Floppy

disk, $259.95. Personal Soft-ware, (see above address).TRS-80

Armadillo Bug, utility pro-gram to manipulate machine-language routines for theTRS-80 Color Computer.Cassette, $12.95. ArmadilloSoftware, POB 7661, AustinTX 78712.

Attack Force, a graphicsarcade game for the TRS-80.Floppy disk, $19.95. Big FiveSoftware, POB 9078, VanNuys CA 91409.

Cosmic Fighter, a graphicsarcade game for the TRS-80.Floppy disk, $19.95. Big FiveSoftware, (see above address).

Faster, a utility programfor TRS-80 Model I and IIthat speeds up the executiontime of BASIC programs.Cassette, $29.95. ProSoft,POB 839, Hollywood CA91603.

Galaxy Invasion, a graphicsarcade game for the TRS-80.Floppy disk, $19.95. Big FiveSoftware, (see above address).

Meteor Mission II, agraphics arcade game for theTRS-80. Floppy disk, $19.95.Big Five Software, (see aboveaddress).

Super Nova, a graphics ar-cade game for the TRS-80.Floppy disk, $19.95. Big FiveSoftware, (see above address).

Tanjali, mind game com-paring shapes and colors forthe TRS-80 16 K Color Com-puter. Cassette, $29.95.Strawberry Software Inc,

POB 743, Vashon Island WA

98070.

CP/M

Analiza, a computerizedpsychiatrist for the Commo-dore CP/M computer sys-tem. Eight-inch floppy disk,$35. SuperSoft Associates,POB 1628, 40 Main St, Suite401, Champaign IL 61820.

SELECT, a CP/M word-processing system. Eight-inchfloppy disk, $595. Select In-formation Systems, 919 SirFrancis Drake Blvd, KentfieldCA 94904.

Other Computers

Intruders and Airwar,graphics games for the In-teract computer. Cassette,$10. Ernie Piette, 110 Hill-crest Rd, Pineville LA 71360.

Schedule, a utility programto help organize daily ac-tivities for the North Star

computer. Floppy disk,$19.95. Azimuth Associates,POB 1636, Arlington VA22210.

Shuttle Ascent Simulation,a graphics arcade game forthe Atari 800. Cassette,$9.95. Starbound Software,POB 214, Cocoa Beach FL32931.■

BYTE's Bugs

PR Problems

The letter entitled "Plot:North by Northwest," byWilliam McWorter (May1981 BYTE, page 14), wasfound to have a bug in line 10of the program. The first "p"in line 10 should have been an"r." The line should read:

10 A$ = "rqvwrsvupqpwtstu"

Many thanks to all who wrotein with the correction.■

"THIS IS DIGITALKEROUT 127,0

This is all it takes to say this or 143 other expressions with MICRO-MOUTH*. No software drivers or subroutines to load. MICRO-MOUTH*, the latest Circuit Celler product can be used as anemergency annunicator, as an aid for the handicapped, for processcontrol and to add dimensions to computer games.Sample phrases that can be programmed are:"THE TIME IS 4 HOURS 23 MINUTES . . . (BEEP)""THE SPEED IS 100 METERS A SECOND . . .SLOW DOWN"Thousands of expressions can be added by changing the ROM chips.MICR0M0UTH* is plug compatible with APPLE II and TRS-80*.Directions included for S100. H8 and parallel port operation.As featured in BYTE, June, 1981

Complete Kit: APPLE II $120.00

TRS-80 Model I .$150.00Assembled and tested:

APPLE II $150.00

TRS-80 Model I w/power

supply and cable $170.00

TRS-80 Model III $200.00

■MICR0M0UTH is a trademark cl Miccominl Inc"OIGITALKER is a trademark ol

National Semiconductor Corp

MICROWIINT INC.

917 MidwayWoodmere, N.Y. 11598Dealer Inquiries Invited

Call 1-800-645-3479,in N.Y. 1-516-374-6793

Circle 348 on inquiry card.

September 1981 © BYTE Publications Inc 383

Big Five Software

Gregg Williams, Senior Editor

It may seem to many readers that BYTE's Arcadehas concentrated on games for Apple and Atari com-puters. In a sense, this is natural; after all, bothmachines have excellent graphics, color, and soundcapabilities—assets with which Radio Shack's TRS-80Models I and III are less endowed. Given the coarsegraphics, lack of color, and limited sound capabilitiesof the Radio Shack computers, what do they have intheir favor?

The answer is: the ingenuity of Bill Hogue and JeffKonyu.

Bill and Jeff comprise Big Five Software, a companythat has developed an unequaled line of arcade-likesoftware for the TRS-80. At the time of this writing,they had five games. Their first, Super Nova (an adap-tation inspired by the Atari game, Asteroids), wasreviewed in the May 1981 BYTE's Arcade (page 108).The three games I will describe here are Attack Force(similar to the arcade game Targ), Cosmic Fighter(similar to Cosmic Patrol), and Galaxy Invasion(similar to Galaxian). At present, they also have agame called Meteor Mission II, which resembles the ar-cade game Lunar Rescue.

Attack Force

Attack Force is my favorite game. The player drivesa single ship in one of four directions around a "city"seven blocks square. Eight Ramships roam the avenuesof the city with the sole intent of ramming anddestroying your ship. You can fire missiles at the at-tackers, and are allowed to lose three ships before thegame ends.

Several features make this a fascinating game. TheFlagship (on the right edge of the screen in photo 1) canzap a Ramship and change it into a Flagship,' or it cansimply step into the boundaries of the city and starthunting your ship. A Flagship is especially dangerousbecause it can fire even when you're not in its line of

sight. Once you clear the screen of all eight enemyships, you get a stunning visual and aural display(that's right, this game has sound effects), bonuspoints, and a new set of enemy ships that aresomewhat faster and net you more points whendestroyed. Each score of 10,000 points gives you anextra ship (as in the other games described in this arti-cle), and, like all popular arcade games, the game getsharder and harder until you are inevitably overcome.One feature that makes Attack Force particularly in-teresting is a practical joke that occurs at one point in

At a (~llanrf>

Name

Format

Attack Force, Cosmic

Cassette or 5-inch floppy

Fighter, Galaxy Invasion

disk

Type

Language

Arcade-style games

Z80 machine code

Manufacturer

Computer

Big Five Software

Radio Shack TRS-80 Model

POB 9078-185

I or III with either 16 K

Van Nuys CA 91409

bytes (cassette version), or

(213) 782-6861

32 K bytes and one disk

(phone orders only)

drive (disk version)

Price

Documentation

Model I/Model III cassette

Color leaflet plus documen-

version, $15.95; Model

tation in program

I/Model III disk version,

$19.95

Author

Bill Hogue

384 September 1981 © BYTE Publications Inc

Photo 1: Attack Force in progress.

the game. I won't tell you what or when, so that you canbe as surprised and delighted as I was.

Cosmic Fighter

Your ship appears at the bottom of the screen and youtry to destroy a wave of alien ships that slowly drift fromthe top to the bottom of the screen in Cosmic Fighter.The alien missiles can move either straight or diagonallydown the screen (see photo 2), and once you destroy thefirst wave (or let them go off the bottom of the screen), anew, more intelligent wave of aliens appears. Occasion-ally, a deadly Flagship that can fire from any angle ap-

pears—you have to destroy this one quickly. If you sur-vive four waves of aliens, you have the chance to fight offthe Flagship near your space station and then dock to getextra fuel for the next round. This time, however, thewave of enemy ships requires two hits per ship todestroy. This continues until you either lose three shipsor run out of fuel.

Galaxy Invasion

Galaxy Invasion is a surprisingly faithful rendition ofthe popular Galaxian arcade game (which is itself a varia-tion of the original Space Invaders). In Galaxy Invasion,you have a ship at the bottom of the screen that shoots upat a formation of enemy ships (see photo 3). The enemyships don't move toward you, but instead send out attackgroups that "peel off" the main formation, glidingdiagonally down the screen and strafing the area theycover with missiles. The ever-present Flagship is just asdangerous in this game as it is in the others. A partic-ularly nice feature is the different kinds of alien ships, allof which flap graphic "wings," both in the main forma-tion and during strafing runs. In fact, it's difficult to im-agine how Bill Hogue (who programs all the games) ob-tains such smooth movement of so many objects on thescreen.

Galaxy Invasion lacks the color and the whining soundof attacking enemy ships, but is nonetheless amazinglyclose to the original arcade game that costs $.25 to play.

Common Features

All the games use the TRS-80's arrow keys for shipmovement and the space bar for missile firing. Unlike

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Photo 2: Cosmic Fighter in progress.

Photo 3: Galaxy Invasion in progress.

September 1981 © BYTE Publications Inc 385

many microcomputer -based arcade games that exhibit adelay between a keypress and the reaction to it, thesegames always respond immediately to any keypress. Allthe games reviewed here also generate sound effectsthrough the TRS-80 tape recorder and earphone (a stan-dard method to get sound effects in a TRS-80). Althoughthe sound is rough and scratchy, it adds immensely to thearcade quality of the games, the most frequent soundeffects occurring every time you fire a missile or an explo-sion occurs.

Each of the games starts with a fancy billboard out-lined in flashing lights, which also contains the names ofthe ten top scorers. (My only criticism is that for a homeenvironment, ten names seem too many; five would giveyou more incentive to excel.) If you make one of the topscores, you put your initials into the billboard display.

From the beginning display you can either get a screenof instructions or start the game. All three games allowone or two people to play at the same time. A game maybe aborted at any time.

Not only are these games fun to play—they arereasonably priced. At the time of this writing, two ver-sions of each game were available (all supplied oncassette). One tape runs on both a TRS-80 Model I and aModel III with 16 K bytes of memory and costs $15.95.

A disk version of each game is available for $19.95 (onegame per disk); the disk will run on any Model I or ModelIII TRS-80 with 32 K bytes of memory and one diskdrive.

Big Five also sells a joystick adapter ($39.95) thatallows you to connect the rugged Atari joysticks to yourTRS-80. All Big Five Software programs will respond to ajoystick, and although I have not seen the adapter unit, 1am confident it is of high quality.

Conclusions

• To the best of my knowledge, Attack Force, CosmicFighter, and Galaxy Invasion are the best arcade-stylegames available for the TRS-80 Models I and III. In fact,they represent some of the best examples of microcom-puter game animation that I have ever seen. They are aschallenging as their arcade counterparts and, as much aspossible, overcome the limitations of the TRS-80graphics.

• Each game is based on an arcade-type game but adds itsown distinctive touches. All games use both sound andextensive graphics.

• The games are reasonably priced (especially in com-parison to graphics games that range from $20 to $40each) and are, in my opinion, a "best buy."B

The Prisoner

Bob Liddil, POB 66, Peterborough NH 03458

You're on an island with your every need providedfor—everything, that is, except your freedom. Theisland's caretaker is watching and experimenting, hisultimate goal is to take away the last scrap of individ-uality you possess. It's you against the island. You areThe Prisoner.

The Prisoner, by Edu-Ware Services Inc of CanogaPark, California, offers a unique, sometimes bizarre,recreation of an early 1970 s TV series that has attainedcult status in recent years. To play the game, you assumethe role of a disenchanted member of a covert intelligenceagency. You're fed up with The Company—the wholesystem in general. After quitting the service, you're ab-ducted and spirited off to The Island, an isolated, self-contained community where electronic surveillance,brainwashing, plots and counterplots, illusions, delu-sions, and confusions are the order of the day.

This program is not in the Adventure format that hasbecome so popular over the last year. It is, in fact, agraphics-oriented, disk-accessing collection of fixed andrandomized events that leaves you pounding your desk inendless frustration trying to make heads or tails of it.This is not necessarily bad because that is the program'sintent.

The game is fundamentally a contest between twoequally difficult goals. The computer wishes to obtainyour resignation code (and, not incidentally, doesn't carehow insane it drives you). You, on the other hand, wishto escape from The Island and must use every possiblemeans to do so.

By studying the documentation carefully, you learn(well before booting the disk) that the program is going tolead you on an incredible journey. Before the gamebegins you are assigned a resignation code. The

386 Septembtr 1981 © BYTE Publications Inc

documentation explains that this code is a condensationof your reasons for leaving The Company. When youawaken, the game begins in room #6, which contains atime-consuming invisible maze that is never the sametwice. If you escape the maze, the machine greets you byasking you to identify yourself. Considering the twenty-minute invisible maze and the possible frustration of hav-ing to restart the game due to misinterpreting thescreen—the tricks start coming right at the begin-ning—the inattentive player is in for rough sailing.

Once in the courtyard, the movement codes are dif-ferent from those in the maze. A dead keyboard raises thefrustration level before you realize that this is preciselywhat the author, in the guise of The Caretaker, or Masterof the Island, is trying to do.

Subsequent scenarios are contained in twenty"buildings," each of which you may enter at any time.The trick is to survive and outwit the event once you'reinside. For example, there is the Hospital, where an en-counter with a "shrink" might be expected, and at theTown Hall you must play politics. There is a Bank, aCourthouse, a Church, and so on. All these locations areriddled with pitfalls and potential disasters. They are alldesigned to get you to throw in the towel and reveal yourcode.

The program uses an awesome mixture of graphics,sound, and text. There are high-resolution pictures withbeeps and whistles and low-resolution pictures that con-found you with simplicity. At times, portions of the pro-gram "jump loose" and seem to suffer a programming er-ror. However, the program is not in error—it does this bydesign. It's a nightmare. The program doesn't do whatyou think it should.

The Prisoner is not for the easily frustrated, nor forthose looking for a shoot-em-up arcade-type game. In-stead, The Prisoner is complex beyond belief, nearlyunbeatable, and at times irrational on purpose; careeningthrough a calculated mind-warp, its sole function is toentertain.

If you follow the rules, trust your fellow man, ordisplay anything less than a total commitment to anti-social, anti-island behavior, you will be hopelesslydoomed to repeated failure.

Author David Mullich, a computer science student atCalifornia State University, Northridge, is a meticulousresearcher with an artist's eye for depth and detail. Inspeaking about The Prisoner, he said: "I was sick andtired of all the arcade games and (conventional) Adven-ture games. They seemed to be imitations of each other."

As a youngster Mullich enjoyed The Prisoner on TVand found that, as a young man, the themes appealed tohim. "I dreamed of doing a program on The Prisoner,and through Edu-Ware, I got the chance," he said.

. Afa Clanrp

Name

The Prisoner

Language

Applesoft BASIC

Type

Epic nonclassical adventuregame

Computer

Apple II or Apple II PlusApplesoft and 48 K bytes of

Manufacturer

memory

Edu-Ware Services Inc22222 Sherman WayCanoga Park CA 91303(213) 346-6783

Documentation

12-page booklet

Audience

Price

Puzzle solvers, adventure

$29.95

fans and students of the

Author

weird

David Mullich

Mullich's version of The Prisoner, though not untrueto the series, is a product of his vivid imagination. It willappeal to puzzle solvers and seekers of the bizarre. ■

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September 1981 © BYTE Publications Inc 387

Software Review

Three Microcomputer LISPs

Steven P Levitan and Jeffrey G Bonar

Computer and Information Science Department

Graduate Research Center

University of Massachusetts

Amherst MA 01003

"(TELL ME MORE ABOUT YOURFAMILY)" With these immortalwords, Joseph Weizenbaum's ELIZAprogram confronted the world withthe power of artificial intelligence(AI) techniques. A good deal of thatpower comes from the expressivenessof the programming language LISP.Some sophisticated and powerfulLISP software packages are nowavailable for microcomputers. In thisarticle, we review three LISPs, one ofwhich is distributed with a modernversion of ELIZA. The LISP packagesare muLISP/muSTAR from The SoftWarehouse, Cromemco LISP fromCromemco Inc, and (T.(L.C)) fromThe LISP Company.

We have compared two basicissues: speed and functionality. In theLISPs reviewed, you will see thatthese two aspects are continuallytraded off: the slower LISP has morecapabilities. The trade-off is morecomplex than in most languages,though. Due to the extreme flexibilityof LISP, any feature of one LISPpackage can usually be emulated inanother LISP package at the cost ofincreased run time.

LISP purchasers should realize thatLISP is anything but a standardizedlanguage. Most LISPs are fairlyidiosyncratic, representing manyyears of development, modification,and tailoring by their designers andusers. The microcomputer-basedLISPs are no exception. This cancause problems for new LISP users. A

LISP you purchase may look quiteunlike some of the dialects discussedin textbooks. Furthermore, manyfeatures of LISP are rarely discussedin texts, but they are quite useful forLISP programming.

Overview

muLISP successfully provides auseful artificial-intelligence develop-ment system to the microprocessoruser community. It is billed as morethan a LISP interpreter for the Z80,and it is a good bit more. It provides areasonable set of LISP functions andspecial forms. It also supports theuser with muSTAR, a developmentsubsystem that makes entering anddebugging code as painless aspossible.

On the positive side, muLISP runsremarkably fast and allows for thecreation and execution of fairly largeLISP programs. On the negative side,some of the design decisions abouterror handling and type checkingmake debugging in muLISP harderthan need be. In particular, muLISPprovides almost no facilities to detectobvious nonsensical programs, and itdoes not allow a user to examine thedata stack after an error or user inter-rupt. We like the ideas that motivatedthe muSTAR development sub-system, but are disappointed by someof the holes in the design. In par-ticular, it is not easy to alternate be-tween the high-efficiency environ-ment and the development environ-

_At a Glance.

Name

muLISP/muSTAR-80 version 10/06/80

Type

Version of LISP programming language

Manufacturer

The Soft WarehousePOB 11174Honolulu HI 96828

Price

$200, from Lifeboat Associates1651 Third AveNew York NY 10028(212) 860-0300;$200, from Microsoft10800 NE Eighth, Suite 819Bellevue WA 98004(206) 455-8080

Format

5-inch or 8-inch floppy disk

Language used

8080 or Z80 machine language

Computer needed

8080-, 8085-, or Z80-based computer withat least 20 K bytes of memory, runningunder a CP/M-compatible operatingsystem

Documentation

100 pages, 8Vi by 11 inches (22 by 28cm), in a 3-ring binder

Audience

Students, educators, computer-languageenthusiasts

388 September 1981 © BYTE Publications Inc

ment. Also, the screen editor is notadaptable to all terminals. The exam-ple programs delivered with thesystem are interesting and give just ahint of the power of a micro-computer-based LISP system.

John Allen, who served as guesteditor for the August 1979 BYTE LISPissue and wrote Anatomy of LISP, isthe primary author of both theCromemco and (T.(L.Q) LISPsystems. Therefore these two LISPsare similar in most respects and willusually be discussed together. Webelieve that they are, in fact, differentrevisions of the same program. TheseLISPs are also a successful attempt tobring LISP into the world ofmicroprocessors.

In many respects, Cromemco LISPand (T.(L.C)) LISP are more modernthan muLISP. They lack an in-tegrated development environment,but include many more intrinsic func-tions and data types, helpful typechecking, and error detection. Theextra functionality is provided at theexpense of speed, but we feel thatthese LISPs still run acceptably fast.Our most important criticism is of thesmall, fixed-size stack. These LISPsdo not allow one to write the power-ful recursive functions that makeLISP such a clean and elegantlanguage. This is not necessarily apractical limitation since iteration iscleanly supported,, but it is rather in-elegant and unaesthetic.

Data Types in LISP

Most modern programminglanguages support a variety of datatypes. So do modern LISPs. In addi-tion to the basic atoms, integers, lists,and property-list data types, differentLISPs support "infinite-precision" in-tegers, floating-point numbers,character strings, arrays, and Pascal-like records. For now, we ignore thefact that functions and special formsare also data types in LISP. Wediscuss them separately below.(Special forms are things that looklike LISP functions, but have specialconventions for their evaluation.COND is an example of an intrinsicspecial form.)

The inherent flexibility of the basic

LISP data types allows almost anyother data type to be emulated, but ata considerable price in executionspeed and/or memory space. For ex-ample, we could emulate a characterstring as a list of single-letter atoms,but operations performed at the endof the "string" would be quite expen-

sive. Furthermore, assuming a two-byte address, more than in byteswould be needed to store anK-character-length string. One wouldlike a LISP implementation to directlysupport a variety of data types usingmachine-level data structures andoperations.

Af a danrp

Name

Language used

Cromemco LISP, version 1.06

Z80 machine language

Type

Computer needed

Version of LISP programming language

Z80-based computer with at least 48 K

bytes of memory, running under

Manufacturer

Cromemco's CDOS or Cromix operating

Cromemco Inc

systems

280 Bernardo Ave

Mountain View CA 94043

Documentation

(415) 964-7400

135 pages, &Vi by 11 inches (22 by 28

cm), in 3-ring binder; includes various

Price

CDOS manuals and a copy of Artificial

$295

Intelligence Programming

Format

Audience

5-inch or 8-inch floppy disk

Students, educators, computer-language

enthusiasts

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September 1981 © BYTE Publications Inc 389

Circle 86 on inquiry card.

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Support of many data types doesnot imply strict type checking, as inPascal. LISP style dictates that"reasonable" data-type conversionswill happen automatically. For exam-ple, if an operation performed on twointeger values yields a value notrepresentable as an integer, onewould expect LISP to return afloating-point or infinite-precision in-teger as the value.

Cromemco and (T.(L.C)) LISP sup-port a richer set of data types thandoes muLISP. They support atoms,14-bit integers, floating-pointnumbers, single characters, strings upto 256 characters long, lists, and pro-perty lists. Atoms in these LISPs cantake only one value. This contrastswith many LISPs, including muLISP,which allow an atom to have twovalues, one interpreted as a function.Each atom does have an associatedproperty list.

Cromemco and (T.(L.C)) LISP

_At a Glance.

Name

(T.(L.C)) LISP version 1.07

Type

Version of LISP programminglanguage

Manufacturer

The LISP Company18215 Bayview DrLos Gatos CA 95030(408) 353-2227

Price

$150

Format

5-inch or 8-inch floppy disk

Language used

Z80 machine language

Computer needed

Z80-based computer with at least 48 Kbytes of memory, running under a CP7M-compatible operating system

Documentation

135 pages, 8Vi by 11 inches (22 by 28 cm)

Audience

Students, educators, computer-languageenthusiasts

check data types fairly strictly. Forexample, single characters, denotedwith a back slash (" \"), are notdirectly comparable to strings oflength one, nor are they directly com-parable to single-character atoms.Similarly, the string "123" is notdirectly comparable to the integer123. Of course, functions are provid-ed to convert between types.Cromemco and (T.(L.C)) LISP doprovide facilities for building andsupporting user-defined data types.

Cromemco and (T.(L.C)) LISP dohave functions that behave different-ly depending on the type of argumentpassed in. For example, the ASCIIfunction yields an integer whenpassed a character and a characterwhen passed an integer:

(ASCII \ C) returns 67(ASCII 67) returns \ C

The details of how these data struc-tures are implemented are hiddenfrom the users of (T.(L.C)) LISP. The"clever tricks" which this prevents areno loss to most programmers. TheCromemco LISP manual does discussdetails of these data structures for usein writing external assembly-languagefunctions.

muLISP supports atoms (callednames in the manual), infinite-precision integers (actually, theymust be in the range ±256253), lists,and property lists. Each name cantake two values—a value that isreturned when the name appears as afunction call, and a value that isreturned in all other situations. Eachname also has an associated propertylist. Strings are partially supported byallowing manipulation of the printnames of atoms.

muLISP does almost no type check-ing. The manual discusses the im-plementation of the different datatypes very early, and someknowledge of this implementation isimportant in using the system. Manyoperations are defined for all datatypes, irrespective of whether thismakes any sense. CAR and CDR, forexample, will work perfectly well onnumbers. This may be useful in somesituations, but it often causes confus-

39 0 September 1981 © BYTE Publications Inc

ing results and subtle bugs. We feelthe marginal extra functionality andgenerality provided in this way areonly an invitation to poor code,obscure hacking, and subtle bugs. If itis necessary to explicitly manipulatean internal representation, thereshould be an explicit function to dothis. Of course, muLISP saves bothtime and space by not checking datatypes.

User-Defined Special Forms

In a LISP system, one wishes towrite things which look like func-tions, but behave differently. For ex-ample, we would like to write things

like the standard LISP AND:

(AND predicate-1 predicate-2 . . .predicate-n)

AND evaluates each predicate-i inorder, stopping if any predicatereturns the value NIL (the standardLISP representation of the Booleanvalue false). There are two indepen-dent problems with writing AND as astandard LISP function. First, how dowe pass an indefinite number ofarguments, and second, how do wepass the parameters unevaluated?Special forms allow us to tell thesystem to treat the parameters in a

special way. Below, we follow LISPconvention and use the word form asa general term for both functions andspecial forms.

muLISP solves the problem of anindefinite-length parameter list withno-spread forms, in which there isonly one formal parameter. (A for-mal parameter is a dummy variable inthe form definition.) When a no-spread form is called, a list of allarguments is bound to that single for-mal parameter. The form uses this listof arguments in any way desired.

In muLISP, call-by-name forms arespecified with NLAMBDA (for Noevaluation of LAMBDA) instead of

Listing 1: Definition of AND-1 in muLISP.

(LAMBDA (PRED-LIST)(COND

((MULL PRED-LIST) 1)

7. we have reached the end of the predicates'/. and all hi*vt* evaluated non-NIL -7. return T.<(EVAL (CAR PRED-Lim ) )

(AMD-1 (CDN PRDIMLIST)>)7. eval the next predicatei if non-NIL"/, recur on I he rest(T NIL)

7. otherwise, the last predicate was false.7. exit with Nil.))

Listing 2: A LISP function to print out the integers from 1 to N. The version in listing 2a is the function written in muLISP. The ver-sion in listing 2b is the function written in either Cromemco LISP or (T.(L.Q) LISP.

(2a)

(LAMBDA (N)

(SETQ COUNT 1)(LOOP

(PRINT COUNT)

( (EQ COUNT N) N) X exit test

(2b)

(LAMBDA (N)(DO

(SETQ COUNT (PLUS CUUN'I 1))))

( (COUNT 1 (PLUS CDUN'I I)) )

; Only one local variable. COUNT. It is; initialized to 1, and incremented on; each iteration

( (EQ COUNT N) N )

i Only one exit test. It specifies an

; exit with value N when count equals 101

(PRINT COUNT)

; The body contains only the PRINT

) )

September 1981 © BYTE Publications Inc 391

LAMBDA. Normal (LAMBDA) func-tions are call-by-value and evaluateeach actual parameter, binding for-mal parameters to the values of theactual parameters. (Actual param-eters are the expressions appearing asarguments to a function call.) In acall-by-name function, the formalparameters are bound directly to theactual parameters. If evaluation isdesired for any of these parameters, itis explicitly specified with EVAL.

We can write a muLISP version ofAND defined as:

(NLAMBDA PRED-LIST(AND-1 PRED-LIST))

Because AND is a call-by-name no-

spread form, all its actual parametersare gathered, unevaluated, into a listthat is bound to PRED-LIST. AND-1is called with PRED-LIST as its singleparameter. AND-1 is a call-by-valuespread function. AND-1 is thendefined as shown in listing 1.

In summary, muLISP supports twotypes of forms—call-by-value andcall-by-name—and two parameter-binding styles—spread and no-spread. All four combinations arepermitted and useful. muLISP formsare compiled in a way that is largelytransparent to the user.

Cromemco and (T.(L.C)) LISP alsoallow both call-by-value and call-by-name (referred to as "call-unevaluated" in the manual) forms.

Additionally, LISP macros are sup-ported. A LISP macro has only oneparameter, which is bound to thecomplete text of the expression thatcalls the macro. For example, con-sider a macro TEST, which is calledwith the following expression:

(TEST JOE (CAR A) 5)

The formal parameter of TEST wouldbe bound to the expression:

(TEST JOE (CAR A) 5)

The macro body is then free tomanipulate the original expressionwith the full power of LISP. The

Issue Discussed

Cromemco and (T.(L.C)) LISP

muLISP

Cost

$295-Cromemco*$150-(T.(LC))

$200

Data types supported

•Atoms, integers, floating-point, characters,strings, lists, property lists

Atoms, strings, infinite integers, lists, propertylists

Type checking

*yes

no

Number of intrinsic functions

*145-Cromemco; 144-(T.(LC))

71

Parameter options

•Optional, auxiliary, rest

Spread or no-spread

Special forms

•Macros, read-macros "call-by-unevaluated"

"Call-by-name"

Control flow

DO, PROG1, PROGN, COND, AND, OR,CATCH, THROW

LOOP, implicit sequencing, PROG1, COND,implicit conditional, AND, OR

Input and output at the terminal

Allows backspace

•Allows backspace, retype line, abort line

Program saving and restoring

Text files, absolute memory image, auto-load

Text files and compressed internal image files

Program-controlled input and output

•Well done, I/O functions work on strings

Well done

Space management

Dynamic space allocation for all data types,the stack is fixed in size and too small

•Dynamic space allocation for all data typesand the stack

User environment

Simple environment for developing,debugging, and executing programs; ability toexamine the data stack after errors, extensiveerror checking; tracing abilities

Separate development (muSTAR) andexecution (muLISP) environments; no abilityto examine the data stack after errors; toolittle error checking; muSTAR includes ascreen editor; tracing abilities; source codefor muSTAR included

Linking to assembly language

Cromemco-well documented and supported(T.(L.C))-not supported

Possible but poorly documented

Documentation/library software

Clear manual suitable for beginners; manyexamples

Clear user's manual; too terse and formal forbeginners; includes several utilities andgames

Speed

Adequate

*4 to 7 times faster than the others

Table 1: Comparison chart for the versions of LISP reviewed. This table summarizes the differences discussed in the text. For eachissue discussed, an asterisk (*) denotes the LISP the reviewers consider to be superior. The absence of an asterisk denotes a tieamong the three versions.

392 September 1981 © BYTE Publications Inc

Expression evaluated in TESTER loop

(T.(L.C))counts

Cromemcocounts

muLISPcounts

NIL

LC

DC

BIGCAR

BIGCDR

'(HAS-AS-MEMBER-I 'B LONG1)

'(HAS-AS-MEMBER-R 'B LONG1)

'(REMOVE-ELEMENT-I 'B LONG41)

'(REMOVE-ELEMENT-R 'B LONG41)

'(HOW-RELATED 'FRODO-B 'BILBO-B)

Notes:

8122

265

408

556

555

119

79

84

64

3

8061

258

409

549

552

119

79

85

66

3

31260

1667

2100

4316

4200

704

367

24

318

16

• All of the above expressions were evaluated as many times as possible in 30 seconds (60 seconds for the call to HOW-RELATED). Thecounts represent how many complete evaluations occurred in that time.

• The counts given represent an average of three separate trials, except for the Cromemco counts, which represent one trial. The oneCromemco trial was run to verify the similarity between (T.(L.Q) and Cromemco LISP,as explained in the text.

• muLISP performs particularly slowly with REMOVE-ELEMENT-I because this function uses APPEND, which is not intrinsic to muLISP. Torun REMOVE-ELEMENT-I we used the recursive version of APPEND supplied in the muLISP utility library. The use of an interative APPENDwould improve the performance shown.

• These tests were run on a Cromemco C3 Z80-based system with 64 K bytes of memory running at 4 MHz.

• The amount of available memory influences these results in two opposing ways. More memory means fewer garbage collections, but thegarbage collections that do occur last longer.

Table 2: Timing results for the LISP benchmark programs. For details on how this table was compiled, see the text box "Notes onLISP Benchmarks."

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September 1981 © BYTE Publications Inc 393

value computed, however, is thenitself evaluated, yielding the finalvalue of the macro call. Often a prob-lem is best solved by manipulatingthe text of a form's call. Macros allowthis manipulation in a clean way.Macros are particularly suitable forhiding data-structure implementa-tions.

Cromemco and (T.(L.C)) LISPallow a very general formal-parameter-list specification for call-by-value functions. In particular, onecan specify regular parameters, op-tional parameters, auxiliaryparameters, and a rest parameter.Optional parameters are bound to aspecified default value if they are notspecified as an actual parameter.Auxiliary parameters are localvariables to the function, and theyare specified with an initializationvalue. The rest parameter is bound toa list of all actual parameters notbound to a formal parameter of someother type. This is more flexible thanthe no-spread parameter of muLISP

because some actual parameters canbe required even though the totalnumber is indefinite. The call-by-name and macro forms of Cromemcoand (T.(L.C)) LISP also allow thedefinition of auxiliary parameters.We found this sophisticatedparameter list to be quite useful andconcise once we were familiar with it.

LISP Control Structures

Because LISP uses the samerepresentation for data and pro-grams, the difference between controlstructures and data structuresbecomes blurred. For example, onefunction may construct a list which isthen evaluated as a function call. Wehave done this in the function BUILD-LONG-CONS in listing 3. For thepurpose of this review, we considerany construct that affects the order ofexpression evaluation to be a controlstructure. LISP easily allows thedefinition and integration of new con-trol structures that reflect the needs ofa particular problem. In particular,

the LISPs reviewed here allow one tocreate new control structures usingthe special forms described above.This means that if you like a controlstructure in one LISP, you canusually emulate it in another.

Sequencing Control Structures

The simplest control structureallows one to evaluate a sequence ofexpressions. In muLISP, sequentialevaluation is implied by puttingseveral expressions to be evaluatedinto a list. For example:

((PLUS 3 4) (CAR (QUOTE (A B)))(SETQ Z 6))

returns:

(7 A 6)

and binds 6 to the atom Z. Also pro-vided is the PROGl form whichreturns the value of the first expres-sion it evaluates, but also evaluatesText continued on page 396

Listing 3: Benchmark functions for versions of the LISP programming language. These functions are used either to build expressionsused in the timing benchmarks or as functions to be benchmarked. BUILD-LONG-CONS, BUILD-DEEP-CONS, and NESTED-APPLICATION are used to build expressions that test CONS, CAR, and CDR. Listing 5 shows how they are used. REMOVE-ELEMENT and HAS-AS-MEMBER represent archetypical LISP functions. They are tested in both a recursive and an iterative form.These functions are written in a neutral "standard" LISP, except for the iterative versions of REMOVE-ELEMENT and HAS-AS-MEMBER. Comments are delimited with braces ({ }). See also table 2 and the text box labeled "Notes on LISP Benchmarks."

build-long-cons

■C Builds a CONS expression which, when evaluated/ willproduce a list LENGTH long of ELEMENT. Example:(BUILD-LONG-CONS 5 'A) returns

(CONS 'A (CONS 'A (CONS 'A (CONS 'A (CONS 'A NIL)))))>

(lambda (length element)

(cond ((zerop length) ni))(t (list 'cons

(list 'quotf element)

(build-long cons (difference length 1)

element)>)))

build—deep-cons

•C Builds a CONS expression which, when evaluated/ will producea list DEPTH deep with the innnermost list containingELEMENT. Example:

(BUILD-DEEP-CONS 5 'A) returns

(CONS (CONS (CONS (CONS (CONS 'A NIL) NIL) NIL) NIL) NIL)>

(lambda (depth element)

(cond ((zerop depth) (litt 'quote element))

394 September 1981 © BYTE Publications Inc

Listing 3 continued:

(t (list 'cons

(bui Id -deep -cons (difference depth 1)

element)nil)) ) )

nested-application

< Builds an expression which, when evaluated, <uill applyFUMCTION to ARG, then FUNCTION to thf results, then tothose results, etc. for a total c»F iJiNGTH times. Example:

(NESTED-APPLICATION 'CAR 5 '(((((A))))) ) returns(CAR (CAR (CAR (CAR (CAR (((((A))))) ) ) ) ) )>

(lambda (function length arg)

(cond ((zerop length) <irc»)(t (list function

(nested -applicationfunction

(difference length 1)arg) ) )))

has-as-member-r

■C Returns T if ELEMENT appears in i S'l. This is the recursiveversion of the function. >(lambda (element 1st)

(cond ((null 1st) nil)

((eq element (car 1st)) t)

(t (has-as-member element (cdr 1st)))))

remove-element-r

■C Returns a copy of LST with all occurences of ELEMENTdeleted. This is the recursive vevt-ion. >(lambda (element 1st)

(cond ((null 1st) nil)

((eq element (car 1st)) (remove-element-r

element(cdr 1st)))(t (cons (car 1st)

(remove-clement element (cdr 1st))))))

has-as-member-i-muLISP

•C The muLISP iterative version of HAS-AS-MEMBER. >(lambda (element 1st)

(setq cdr-lst 1st)

(loop ((null cdr-lst) nil>

((eq (car cdr-lf.t) element) t)(setq cdr-lst (cdr cdr-lst))))

remove-element—i-Crome/nco-tlc

•C The Cromemco/(T. (L. C) > iterative version of REMOVE-ELEMENT. >(lambda (element 1st)

(do ((front nil

(if (eq element (car back))

(append Front (list (car back)))front) )(back 1st (cdr b.uk) > )(((null back) front))))

September 1981 © BYTE Publications Ire 395

Text continued from page 394:all other expressions in order. For ex-ample:

(PROG1 (PLUS 3 4) (CAR (QUOTE(AB)))(SETQ Z 6))

returns 7, but also executes the CAR,throwing away the result, and binds 6to the atom Z.

The implicit sequence evaluation,while convenient, is often confusingand error-prone. Quite often, incor-rect functions evaluate without anerror because there is almost always alegal interpretation of any expression.We feel this disadvantage outweighsthe convenience of the implicit form.

Cromemco and (T.(L.C)) LISP pro-vide PROG1 as well as a PROGNspecial form. PROGN evaluates itsexpressions in sequence, like PROGl,but returns the value of the last ex-pression evaluated.

Conditional Control Structures

The standard LISP form for ex-

pressing conditionality is COND. InmuLISP, COND is implied in any listof expressions. If any element of thelist is of the form:

( predicate expression )

and predicate evaluates to non-NIL,then control exits from the outer listwith the value of expression. Like theimplicit sequence evaluation, thisfeature trades readability and ease ofdebugging for conciseness and speed.Of course, an explicit COND is alsoavailable in muLISP.

The COND form is augmentedwith an IF form in Cromemco and(T.(L.C)) LISP:

(IF predicate expression-1

expression-2 . . . expression-n)

If predicate is true, expression-1 isevaluated and its value is returned.Otherwise, expression-2 throughexpression-n are evaluated, and the

Notes on LISP Benchmarks

The timing benchmarks were designed to test the speed of CAR, CDR, andCONS, the workhorse functions of LISP; the speed of some simple but"archetypical" LISP functions, in both recursive and iterative form; and the speed ofa reasonably large LISP program with several modules. Basically, the benchmarkswere performed in an environment created by defining the functions shown in listing3 and evaluating the expressions shown in listing 4.

To test CAR, CDR, and CONS, we built long nested expressions that invoke onlythese functions. This is done with the functions BUILD-LONG-CONS, BUILD-DEEP-CONS, and NESTED-APPLICATION in listing 3.

We chose REMOVE-ELEMENT and HAS-AS-MEMBER as the "archetypical"LISP functions. In listing 3, we show the recursive versions of each and a sampleiterative version of each. Since iteration constructs differ widely among LISPs, wetailored an iterative version for each LISP to be benchmarked.

Finally, listing 4 shows the genealogy program we developed as our full-size LISPprogram. This program allows one to enter family-tree information through thefunctions BORN, MARRIED, and FIRST-BORN (FIRST-BORN is used when theparents of the new entry are unknown). The family tree is queried by calling thefunction HOW-RELATED with two names. This program has three principal com-ponents. The first group of functions know about kinship. These functions useanother set of functions that perform a breadth-first search through a family tree.Finally, the family tree is implemented with a set of graph-manipulating functionsbased on the language GRASPER.

In listing 5, we entered parts of the BAGGINS and TOOK family trees. Our testthen involved asking how Bilbo Baggins and Frodo Baggins are related. These familytrees can be found in appendix C of ] R R Tolkien's Return of the King.

Timing is actually done by counting the number of times a given expression will beevaluated in a fixed time period. The function TESTER in listing 5 performs theevaluation and counting repeatedly until it is interrupted after a fixed time period.The count is then examined. Note that before entering the main tester loop wealways perform a garbage collection.

results of evaluating expression-n arereturned.

All three LISPs provide the condi-tional logical operators AND andOR:

(AND predicate-1 predicate-2 . . .

predicate-n)

(OR predicate-1 predicate-2 . . .

predicate-n)

If any predicate-i evaluates to NILfor AND, or other than NIL for OR,the form immediately returns withthat value, evaluating no otherpredicate-i.

Recursion and Iteration

LISP is one of the cleanestlanguages in which to express a recur-sive solution to a problem. LISP pro-grams that use only recursion areclean, elegant, and very simple todebug because there are no globalvariables or side effects. Unfortunate-ly, purely recursive LISP programsare usually too slow. Typically, whenan application program is found to betoo slow, a few functions are takingmost of the time. (In our genealogyprogram in listing 4, SONG-1 andSING-1 are the critically slow func-tions.) Once these functions arefound, they can each be optimized,usually by making them iterative.Good LISPs must provide cleaniterative structures which localize anyuse of side effects and easily replacerecursive structures. All LISPsreviewed here have good iterationconstructs.

The LOOP iteration construct ofmuLISP allows any sequence of ex-pressions within the loop body. If anyexpressions are of the form:

(predicate expression)

then predicate is evaluated on eachiteration of the loop. If it is non-NIL,the LOOP returns with the value ofexpression.

Consider the problem of writing afunction to print out the integers from1 to n, returning the value n. InmuLISP this would be written asshown in listing 2a.

The DO iteration construct ofText continued on page 404

396 September 1981 © BYTE Publications Inc

Listing 4: A genealogy program written in LISP. This program is intended to test the LISPs on a moderate-sized program withseveral modules. It allows one to enter family-tree information through the functions BORN, MARRIED, and FIRST-BORN(FIRST-BORN is used when the parents of the new entry are unknown ). The system is initialized with the function CREATE-UNIVERSE. The program has three levels: a group of functions that know about kinship, another group of functions that perform abreadth-first search, and finally a set of graph-manipulation functions that implement the family-tree data structure.

how-related

■C Describes how PI is related to PP.. First we check the simplecases that PI is the same as P2 ,-nd that PI is P2' s spouse.Otherwize. we call DESCRIBE-RELA1 ION after computing thepath in the family tree between PI PP. >(lambda (pi p2)

(cond ((eq pi p2) (lii.t 'mine))

((eq pi (spouse of |>P)> (list

(sex-of-spouse pi)))(t (describe-re)ation pi

P2(find-path-between pi p2))))>

describe-relation

-C Based on a legal connecting path through the family tree/describes how PI is related to PP. PATH-UP-AND-DOWN is alist with the distance up from PI to the lowest commonancestor and the distance down to Pfi Prom the lowestcommon ancestor. We use a LAMBDA binding to cut thislist into components Dl and D2. If either Dl or D2 iszero* the relationship is direct. Other cases are dealt withby NOT-DIRECT-RELATIONS. >

(lambda (pi p2 path-up-and-dotmi)

(cond ((null path-up-«nnd down) '(not

relatedby

blood))(t ((lambda (dl dp)

(cond ((eq dl 0)

(direct-ancestor pi d2))((eq d2 0>

(direct-descendent pi dl))(t (not-direct— relations

Pi

p2

dl

d2)>))(car path-up -and down)(cadr path-up <:n<l-down ) ) ) ) )

direct-descendent

•C The relationship is known to be child/ grandchild) greatgrandchildi or etc. This function invokes choosing theright relation name by sex - son or daughter., and theright number of greats. >

(lambda (younger distance)

(add-grand-greats (sex-of-chiId younger) distance))

d irect-ancestor

■C The relationship is known to be parent, grandparent/ greatgrandparent/ or etc. This function invokes choosing theright relation name by sex - father or mother, and theright number of greats. >(lambda (older distance)

(add-grand-greats (sex-of-parent older) distance))

Listing 4 continued on page 398

September 1981 © BYTE Publications Inc 397

Listing 4 continued:

not-direct-relations

< Based on the distances Dl and D2, determine the relationPI and P2. If Dl and D2 are both one, then PI and P2 aresiblings. If Dl equals D2i and both ore greater than one,then PI is P2's nth cousin/ where n is Dl (or D2) minus one.Finally* if Dl is not equal to Dei. and both are greater thanonei PI is P2's Nth cousin. M removed. N is Dl minus li and M isthe absolute value of the difference between Dl and D2.>

(lambda (pi p2 dl d2)

(cond ((and (eq dl 1) (rq d2 1>) (list

(sex-of-sibling pi)))

((eq dl d2) (lit-t (difference dl 1)

'to us in))

((eq dl 1) (ancestors-sibling pi d2))

((eq d2 1) (sib 1inq& descendent pi dl))

(t (list (difference dl 1)'cousin

(abs (di FPcvence d2 dl)>'removed))))

find-path-between

■C To find a path between PI and P2 we use a breadth first search.Starting at PI we look for P2 onr step away, then twosteps away, etc. The BPEADTH-FIf<S1-SE-ARCH is passed a listof unexpanded nodes and a goal. 'I he- unexpanded nodes arelists with the following information:

-a person to be checked next

-the distance traveled up to got to this person

-the distance traveled down to pel. to this person

-the last person visited before this personWe start with a PI node and initial values on the unexpandedlist. >

(lambda (pi p2)

(breadth-first-search Oif.t (list pi

p',<) >

00' the-great-unknown))

breadth-first-search

■C We take the first unexpanded node of the unexpanded list,if it represents the goal node, vie return its accumulateddistances. Otherwize, we check its relations to see whoneeds to be added as nodes to the unexpanded list. >(lambda (unexpanded goal-node)

(cond ((null unexpanded) nil)(t ((lambda (next)

(cond ((rq (node-of next)goal-node)Oist (dist-up-of next)

(dist-down-of next)))(t (check-relativesnext

goal-node

(cdr unexpanded)))))(car unexpanded)))))

chec k-relatives

398 September 1981 © BYTE Publications Inc

Listing 4 continued:

< Appends new nodes on the end of the unexpended list. Byputting them on the end we get a breadth first search.These new nodes are built by BUILD M-W-UNEXPANDED whichuses various information from thr lort node expanded>

(lambda (last-expanded person unexpanded)

(breadth-first-search (append unexpanded

(bu iId-new—unexpanded(node-of

last-e x panded)(d ist-up-of

last-expanded)(d ist-down-of

last-expanded)(where—oflast-expanded)))pt-iT.on) )

bui ld-new-unexpanded

■C Finds all the neighbors of the rmde last expanded andbuilds unexpanded nodes for them. )f we have notyet started down in the tree (D-.OUWN equals O),we can also build unexpanded nodes from parents of thenode last expanded. In each case we will notethe new distances and the node I«i»t expanded. >(lambda (node d—up d-down from)

(append (make-unexpanded (i-ong node 'child)

noded up

(plus d-down 1)h-om)(cond ((eq d-down 0) (make-unexpanded

(songnode'parent)node

(plus d-up 1)d-downfrom))(t nil))))

make—unexpanded

■C Given a list of nodes and information about how we gotto those nodes/ builds unexpanded nodes for thebreadth first search. We do not make an unexpanded nodefor THE-GREAT-UNKNOWN or for the p]«-(f we were at two stepsago. In this way we avoid infinitely looping throughthe family tree. >

(lambda (node-list from d—up d-down from—from)(cond ((null node-list) nil)

((or (e q (car n o d c -1 i s t)

'the—great -unknown)(eq (car node-list) from-from))(make-unexpanded (ctir node-list)

Prom<• up<i -downfrom—from))(t (cons (list (car node-list)

<i -upd -down

Listing 4 continued on page 400

September 1981 © BYTE Publications Inc 399

Listing 4 continued:

fvnm)

(make-une-xpcrnded (cdr node-list)

fromd-upd-downfrom-from)))))

node-of

■C This and the next three functions select sub fields of anunexpanded node. >

(lambda ( unexpand ed-entry ) (c*;r urn- xpanded-entr y ) )

d ist-up-of

(lambda ( unexpanded-entry ) (c;cJr unexpanded-entry ) )

d ist-down—of

(lambda (unexpanded-entry) (c«*ddr unexpanded-entry))

inhere—of

(lambda (unexpanded-entry) (cfidddr unexpanded-entry))

born

< Allows a user to declare that PERSON of sex SEX was bornto PARENT1 and PARENT2. Various cn*:ph primitives areused to link the new arrival into the family tree. Theseprimitives are explained below. >

(lambda (person parentl parents <.fx>(progn (cun person)

(bun person sex)(cip person 'chiJd parentl)(cip person 'child parent2)(cop person 'p^re-nt parentl)(cop person 'poretit parent2)person))

marr ied

■C Allows a user to declare that PERSON! and PERS0N2 weremarried. The graph processing primitives used to dothis are explained below. >(lambda (personl person2)

(progn (cap personl 'spouse person2)(list personl perr-onS)))

add-grand-greats

■C Adds the right NUMBER of "grand"? and "greaf's to thebasic relationship name ONE-CASE. >(lambda (one—case number)

(cond ((eq_ number 1) (list one—case))

((eq number 2) (list 'grand one-case))(t (cons 'great

(add—grand qreats one-case

(d ifferencenumber1) ) ) ) ) )

add-greats

■C Add the right NUMBER of "greaf's to the basic relationshipname ONE-CASE. Note that "grand "s on- not used. Thisis more common usage for great uncles and aunts. >(lambda (one-case number)

(cond ((eq number 1) (list one-case))(t (cons 'great

4CX3 September 1981 © BYTE Publications Inc

Listing 4 continued:

(add-gveMs one-case

(difference number 1))))))

ancestors-sib 1ing

< Builds up the appropriate kind of uncle or aunt basedon the sex of UNCLE-OR-AUNT and the DISTANCE. >

(lambda (uncle-or-aunt distance)

(add-greats (se x-of-unc. lc-or-aunt uncle-or-aunt)(difference- dif.tance 1)))

siblings-descendent

■C Builds up the appropriate kind of niece or nephew basedon the sex of NIECE-OR-NEPHEW and the DISTANCE. >(lambda (niece-or—nephew distance-)

(add-greats (sex-of-niecc -or-nephew niece-or—nephew)(difference distance 1)))

spouse-of

< Follows NODEs spouse link using *i greph processing primitive. >

(lambda (node)

(car (song node 'spout.e)))

sex-of-chiId

■C This and the next 6 functions chose the appropriate relationname based on the PERSONS name. They all pass a FEMALE-CHOICEand a MALE-CHOICE to CHOOSE-BY-SEX. which actully looksup the sex of PERSON and returns a choice. >(lambda (person)

(choose—by—sex person 'daughter 'son))

sex-of-parent

(lambda (person)

(choose—by-sex person 'mother 'father))

sex-of-spouse

(lamb da (person)

(choose-by-sex person 'wife 'husband))

sex-of-uncle-or-aunt

(lambda (person)

(choose—by-sex person 'nunt 'uncle))

sex-of—niece-or—nephew

(lambda (person)

(choose-by-sex person 'niece 'nephew))

sex-of-sib1ing

(lambda (person)

(choose-bg-sex person 'firter 'brother-))

choose-by-sex

(lambda (person female-choice mi;) e; -choice )(cond ((eq (sex—of person) 'female)female-choice)(t male-choice ) ) )

sex-of

< Uses graph processing primitives to look up the sex of PERSON >

(lambda (person) (vun person))

Listing 4 continued on page 402

September 1981 © BYTE Publications lnc 401

Listing 4 continued:

■C Useful to enter a person whose parents are not known. >(lambda (person sex)

(progn (cun person)

(b un person sex)))

create-universe

< Sets up the two global lists used by the graph processingsystem. The UNIVERSE-NO.DE-LIST i«. a )ist of all the nodesin the system. Here, a node is a person in the family tree.The UNIVERSE-EJDGE-LIST holds all the connections betweennodes in the system. These are kept at triples of (nodeledge node2) to represent an edge called EDGE pointingfrom JMDDE1 to N0DE2. In this casr the edges will befamilial relations. This function al«>o creates THE-GREAT-UNKNOWN who is related to no one. >

(lambda nil

(progn (setq universe node-1ist nil)(setq universe -edge-list nil)(cun 'the-great -unknown)))

cun

•C Creates a node in the universe bi| updating theUNIVERSE-NODE-LIST. >

< lamb da (node)

(progn (setq universe -node -list (cons

node

universe-node-list))node))

bun

■C Binds a value to a node in the universe. Node values arekept on the node's property list/ under the indicator VALUE.Here the value of a node is the per&ons sex. >

(lambda (node value) (putprop node value 'value))

vun

< Get the value of a node in the universe. The converse of bun >

(lambda (node) (getprop node 've-)ue>)

sun

< Set of all nodes in the universe. This is just theUNIVERSE-NODE-LIST itself. >

(lambda nil universe-node-1ist)

cip

•C Create an inpointing edge. This just reverses the argumentspassed to it and calls add-triple which does the work. >

(lambda (nodel edge node2)

(progn (add-triple node*' edge nodel) nodel))

cop

< Creates an outpointing edge, from nodel to node2. As abovebut without the reversal of arguments. >

(lambda (nodel edge node2)

402 September 1981 © BYTE Publications Inc

Listing 4 continued:

(progn (add—triple nodel edge nod<=>2) nodel>)

cap

■C Creates a pair of edges one in e<jch direction. >

(lambda (nodel edge node2)

(progn (cip nodel edge notlr2) (cop nodel edge node2)))

sing

■C Set of nodes mho point to this node- via edges of type EDGE,here we just set up the call for the recursive helperfunction. >

(lambda (nodel edge) <sing-l node! edge universe-edge-list))

s i n g -1

■C This is the recursive version of the helper function for sing.Since this function and song-1 b<)ooi sre the two workhorsesof the graph functions* we used iterative versions in thetiming tests. The recursive versions ere shown here forclarity. The function CDRs down U (initaly the UNIVERSE-EDGE-LIST) looking for a triple of the- form (nodeledge node2) where node2 equals Nl etui edge equals £.Whenever it finds such a triple it CDNSes the nodel elementto the set of nodes to be returned, 'this is just the setof nodes which have edges of type Er which point to Nl. >

(lambda (nl e u)

(c on d ((null u) nil)

((and (eq (cadar u) e) (eq (caddar u) nl>)

(cons (caar u) (<rjnq-l nl e (cdr u))))(t (sing-1 nl e (c ch-' u) ) ) ) )

song

•C Set of nodes which NODE1 points to vie: an edge of type EDGE.This is just like sing above; except it calls song-1. }

(lambda (nodel edge) (song-1 nodel edge universe—edge-1ist))

song-1

•C Identical to sing-1 above except here we are matchingnodel and edge of the triple and returning node2. >

(lambda (nl e u)

(cond ((null u) nil)

((and (eq (caar u) nl) (eq (cadar u) e>)

(cons (caddar u) (*.t>ng-l nl e (cdr u))))(t (song-1 nl e (cdr u)) ) ))

dun

< Destroys a node in the universe by removing it fromthe UNIVERSE-NODE-LIST and the UNIVf-RSE-EDGE-LIST.the real work is done by retripler, and remember below. >

(lambda (node)

(progn (setq universe-node -1ist (remember

nodeuniverse—node—1ist))

Listing 4 continued on page 404

September 1981 © BYTE Publications lnc 403

Listing 4 continued:

(setq universe -edtje -1 ist (retriples

nodeuniverse-edge-list))

node))

remember

•C Remove all ocurrences of NODE in I ) W\. This is just

a simple recursive constructor function. It £DRs down the

list and CONSes together all elements which are not NODE.>

(lambda (node list)

(cond ((null list) nil)

((eq (car list) ncxir) (remember

node

(cdr list)))(t (cons (car list) (remember node (cdrlist))) ) ) )

retrip1es

•C Remove all triples from U (the UNIv\r-!<SE-EDGE-LIST> whereN is either nodel or node2. This eliminates any edgeswhich point to or from node N. >

(lambda (n u>

(cond ((null u) nil)

((or (eq n (caar u>) (eq n (caddar u)))

(retriples n (tdv u)))(t (cons (car u) (i-ctr-ip les n (cdr u))))))

add-tri pie

■C Updates the global UN IVERSE-EDGE--L IS"1 to reflect the netu

edge given by the triple (Nl E Nil). E points from Nl to N2. >

(lambda (nl e n2)

(setq universe-edge-1jft (append universe—edge—1ist

(list(list nl e n2)))))

Text continued from page 396:

Cromemco and (T.(L.C)) LISP ismore complex, more powerful, andmore baroque. Particularly useful isthe ability to specify an arbitrarynumber of local variables, how eachis to be initialized, and how each is tobe modified at each iteration. Also,one can specify an arbitrary numberof exit tests and associated exitvalues. Finally, an arbitrary andpossibly empty sequence of expres-sions make up the loop body. Ourcounting example above forCromemco and (T.(L.C)) LISP isgiven in listing 2b.

Nonstructured Function Exits

Sometimes we want a function to

exit from an arbitrary number offunction call levels. For example, wemight design a system that alwaysallows users to type QUIT to returnto the system's top command level.The CATCH and THROW forms ofCromemco and (T.(L.Q) LISP givethis capability.For example:

(CATCH label expression-list)

says to evaluate the expression-list,much like a PROGN. If, during thatevaluation, the expression:

(THROW label exit-expression-list)

is evaluated, then the CATCH im-mediately returns with the value

returned by treating exit-expression-list as a PROGN. This exit ignoresany intervening computation orpending functions specified within theCATCH expression-list. If a THROWwith the corresponding label is notevaluated, the CATCH is treated justlike a PROGN. Note that the label isjust an atom to establish a cor-respondence between a givenCATCH and THROW.

Input and Output in LISP

Since LISP is a highly interactivelanguage, an implementation musthave high-quality I/O (input/output)capabilities. A user will be involvedwith three similar (and often inter-changeable) aspects of I/O. First,

404 September 1981 © BYTE Publications Inc

there is the common method of in-teraction with the interpreter: typingexpressions and reading the results.Second, there are the techniques ofsaving and restoring disk files con-taining programs and data. Third,there are the input and output opera-tions that happen during user-function execution.

The distinctions here are somewhatarbitrary. Since the difference be-tween program and data is explicitlynot enforced in LISP, it is easy tocreate functions that, for instance,write themselves onto disk. In fact, acommon way to load programs is toredefine the source of expressions forthe "driver" as a disk file rather thanthe keyboard. For the sake of clarity,though, we discuss the three aspects

of I/O mentioned above as separatetopics.

Terminal I/O in all three LISPsleaves something to be desired.muLISP allows for CP/M-stylewithin-the-line editing during input.It recognizes tX (control-X) asrubout; IR as retype line; tU as abortline. It has the usual backspace anddelete characters. If the user, whiletyping an expression, goes beyondone line of text, the system does notreprompt the user. This is especiallyimportant if the user is not sure if theform he or she is typing is correct (interms of matching parentheses). Theuser has no indication from thesystem that it is expecting more inputrather than executing the desired ex-pression.

Cromemco and (T.(L.C)) LISP ac-cept input in an immediate mode.When appropriate, they do not waitfor a carriage return to accept a legalexpression. Unfortunately, theyallow no within-the-line editing ex-cept for backspacing. On a hard-copyterminal, this can be extremelyfrustrating. On a video terminal, thiswould not be a serious problem.

Cromemco and (T.(L.Q) LISPhave very flexible and easy-to-useread-macro capabilities. The inputroutines are table-driven in such away that the user can easily redefinethe meaning of any ASCII (AmericanStandard Code for Information Inter-change) character, even to the pointof causing the system to invoke aText continued on page 407

Listing 5: A set of LISP expressions used to conduct the benchmarks of table 2."/. Expressions to set up the basic benchmarks X

(SETS LC (BUILD-LONG--CGNS 50 'A))

(SETQ DC ( BUILD-DEEP -C0NS 50 ' A ) )

(SETG) LONG CEVAL LC) )

(SETQ DEEP (EVAL DC))

<SETQ BIGCAR (NESTED-APPLICATION 'CAR 49 'DEEP))

(SETQ BIGCDR (NESTED-APPLICATION 'CDR 49 'LONG))

(SETQ L0NG1 (APPEND LONG '<»)))

(DE MIX-4-1 (LENGTH El E2)(COND

( (L.T LENGTH 1) NIL)

(T ( APPEND (LIST El El El El E2)

(MIX-4-1 (SUB LENGTH 5) El E2)))) )

(SETQ L0NG41 (MIX-4-1 50 'A 'B))

X The muLISP version of tester X

(DE TESTER (FORM)(SETQ COUNT 0) X initialize the count X(PRINT (RECLAIM)) X perform an initial slarfoasfa collect X(LOOP X loop infinitlw (until a n e x t e r n a I " i n t e r r u p t") X

(EVAL FORM) X eval the expression to be tested X

(SETQ COUNT (PLUS COUNT 1>> X increment the count %

))

Listing 5 continued on page 406

September 1981 © BYTE Publications lnc 405

Listing 5 continued:

X The next four definitions are helpers to enter the data "/„X base. DF is the Cromemco and (T.(L.C)) LISP function XX to define call-by name? no-spread functions. DE defines XX a call-by-value spread function* %

(DF F (X) (FIRST-BORN (CAR X) (CADR X)>)

(DF B (X) (BORN (CAR X) (CADR X) (CADDR X) (CADDDR X)))

(DF M (X) (MARRIED (CAR X) (CADR X)))

(DF C (X) (C-l (CAR X) (CADR X) (CDDR X)))

(DE C-l (PI P2 CS-LIST)(COND ((NULL CS-LIST) NIL)

(T (CONS (BORN (CAR CS-LIST) PI P2 (CADR CS-LIST))(C-l PI P2 (CDDR CS-LIST))))))

"/. The following expressions enter the BAGGINS and 7.X TOOK family trees. X.

(MARRIED (F BALBO-B MALE) (F BERYLLA-BOFFIN FEMALE) )

(C BALBO-B BERYLLA-BOFFIN MUNGO-B MALE PANSY-B FEMALE PONTO-B MALE

LARGO-B MALE LILY-B FEMALE)

(MARRIED (F LAURA-GRUBB FEMALE) (QUOTE MUNGO-B))

(C LAURA-GRUBB MUNGO-B BUNGO-B MALE)

(MARRIED (F BELLADONNA-TOOK FEMALE) (QUOTE BUNGO-B))

(C BELLADONNA-TOOK BUNGO-B BILBO-B MALE)

(MARRIED (F TANTA-HORNBLOWER FEMALE) (QUOTE LARGO-B))

(C TANTA-HORNBLOWER LARGG-B FOSCO-B MALE)

(MARRIED ( F R U B Y •- B 0 L G E R F E M A I... E ) (QUO T E F 0 S C 0 - B ) )

(C RUBY-BOLGER FOSCO-B DROGO-B MALE)

(MARRIED (F PRIMULA-BRANDYBUCK FEMALE) (QUOTE DROGO-B))

(C PRIMULA-BRANDYBUCK DROGO-B FRODO-B MALE)

(MARRIED (F THE-OLD-TOOK MALE) (F ADAMANTA-CHUBB FEMALE))

( C THE-OLD-TOOK A D A M A N T A - C H U B B B E I... I... A D 0 N N A - T 0 0 K F E M A L E MIR A B E I... I... A - T 0 0 K F E M A I... E )

(MARRIED (QUOTE MIRABELLA-TOOK) (F GORBADOC-BRANDYBUCK MALE))

(C MIRABELLA-TOOK GORBADOC-BRANDYBUCK PRIMULA-BRANDYBUCK FEMALE)

A.

406 September 1981 © BYTE Publications Inc

Text continued from page 405:

MACRO form when it sees a givencharacter.

Although it is possible to redefinethe READ function in muLISP, it isnot as convenient as the read-macrocapability described above. An exam-ple of the usefulness of read-macrosis:

'expression

which, in (T.(L.C)) and CromemcoLISP, will be transformed into:

(QUOTE expression)

Not only is this not done for you inmuLISP, it is not easy to change thesystem to do it.

To overcome the lack of a read-macro capability, muLISP providesauto-quoting. This means that anyatom not bound to a value is boundto itself as a value. This is normallydone for numbers (the value of " 3" isthree), but most LISP systems raise anerror when asked for the value of anundefined atom. The consequences ofthis are discussed further in the sec-tion on error handling.

Disk I/O

Basically, programs are stored ondisk as text files or "internal image"files. Text files here are simply ASCIIfiles of function definitions, atomvalues, and function calls in the same"free-format" style used when typingat the console. Internal image files are"snapshots" of the memory taken atthe time they were created, includingall the bindings of values that were ineffect. muLISP compresses all activedata structures that define the en-vironment and generates a coded filethat can be loaded with the executionsystem. The other two LISPs take ad-vantage of the SAVE utility of CP/Mand CDOS. They exit to theoperating system, and the user mustexplicitly SAVE a memory image ofthe entire user area.

In muLISP, the internal image filescan also be brought in, using LISPfunctions. Restoring an environmentin this way is fast, but it will explicitlydestroy any environment (bindings)that were in effect at the time of the

load. In the other LISPs, one isactually reloading memory with theexact contents it had at the time of theexit. This, again, is done throughCP/M or CDOS and cannot be donefrom LISP.

On the other hand, (T.L.C)) LISPand Cromemco LISP both have anauto-load feature not available inmuLISP. This feature, while com-plicated to use, allows the program-mer to store functions on disk as partof a large virtual memory. Functionscan be stored and loaded only if ac-tually needed (called). After the ex-ecution of the function, the systemcan reclaim the space it occupied(NOKEEP or SMASH), or the func-tion can remain resident (KEEP orNOSMASH) after its first access.

Program-controlled I/O in all threeLISPs is surprisingly easy, partlybecause the LISP language allows theprogrammer to treat programs asdata. Still, "CP/M-compatible" diskI/O is generally a messy subject atbest, and all three of these LISPs doan exceptional job of hiding the gorydetails from the programmer.

Space Management

Since data structures in LISP aredynamic (ie: their size changes duringprogram execution), it is generally agood idea to have dynamic realloca-tion of memory space in a LISPsystem. This means that there is noa priori limit on the number ofvariables, functions, or strings.Rather, as more space is needed forone kind of object, it is found at theexpense of space available for otherkinds of objects.

Cromemco and (T.(L.C)) LISP ac-complish dynamic allocation by atechnique in which memory is brokeninto 256 pages of 256 bytes each. Anyof these pages can, in theory, be usedfor storage of any data type. But theentire page is always used for thesame type of object. This scheme hastwo major advantages. First, itsimplifies type checking. The highbyte of any object's address definesthe type of that object as well as iden-tifying its location. The page-byte-to-type correspondence is kept in a tablein memory. This table allows for thesecond advantage. If more space for a

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given type of object is needed, a pageof memory is allocated by simplychanging the entry in the table foran unused page. If, on the otherhand, an allocated page is made free(by the garbage-collection process),a change to the table allows thisspace to be claimed by another datatype.

Unfortunately, the stack, which isused for both variables and controlinformation, must use a contiguousarea of memory if it is to be fast. Thismeans that when the stack is full thesystem cannot allocate an arbitrary

free page of memory to the stack. Asolution to this would be to moveother data around to free up a pageadjacent to the stack. But, with thepointer conventions discussed above,this would be a very messy and time-consuming job. Therefore, Cromem-co and (T.(L.C)) LISP use a fixed-sizestack. This decision poses a real prob-lem because recursive-style anditerative-style programming makevery different demands on the size ofthe stack. In fact, curiously, the stacksize is fixed regardless of the totalmemory size of the system.

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muLISP uses a truly dynamicscheme. At any time, all data typesare competing for memory. Asdemands for one type increase, theother spaces shrink. Because this in-cludes the stack, space is better usedin this system. The cost of this featureis, of course, time. The user mustwait for data areas to be movedaround during program execution.However, we found the time penaltyto be minimal.

Linking

muLISP and Cromemco LISP bothsupport user-defined assembly-language functions. The current ver-sion of (T.(L.C)) LISP apparentlydoes not. Assembly-languageroutines allow the user to extend hisor her LISP system in various ways.Special functions can be made to runsignificantly faster, or functions canbe written to take advantage ofspecial hardware such as a colorgraphics screen.

The Cromemco LISP system givesthe user extensive, if obtuse,documentation and several supportprograms to allow the user to buildassembly-language routines that arelinked into the LISP system. Once alinked system is created, it can besaved as an internal image file andthen used as the regular LISP system.

The muLISP solution is less am-bitious but still workable. muLISPallows up to four assembly-languageroutines to be incorporated into thesystem. The routines must be calledby jump instructions located in fixedaddresses in memory, and the bodiesof the routines must exist in locations"invisible" to LISP—that is, abovethe operating system, Since theroutines are not in the LISP area, sav-ing an internal image file of muSTARwill not allow the user to reload thelinked system. Rather, the systemmust be regenerated each time it isused. This could be done in astraightforward way using a CP/Mcommand file.

User Environment

muLISP exhibits an approach tothe environment presented by theLISP system that differs from the

408 September 1981 © BYTE Publications Inc

other two LISPs. One example of thisis the idea of having a separatedevelopment environment as well asan execution environment. Adevelopment environment supportsediting and debugging of functions(programs) in an interactive setting.While development and testing can bedone in muLISP's execution system,there are no facilities to make thiseasy. Another example of the dif-ference is the related stance on errorhandling, which is discussed below.The development subsystem,muSTAR, is an internal image filewhich is delivered with the muLISPsystem. (It is an application programwritten in LISP.) muSTAR is a menu-based program that allows for theuser to pick any of the followingoptions:

• Edit Function

• Edit Variable

• Edit Property

• EvalLISP

• Eval-QuoteLISP

• Trace Function

• Untrace Function

• Read File

• Write File

• Select Drive

Menu-based systems are generallydesigned to be used with video ter-minals. This one is no exception: it isa joy on the screen of a 9600 bps ter-minal and very frustrating on a 300bps DECwriter.

The editor that comes withmuSTAR is a flexible screen editor in-tended to be adaptable to any type ofvideo terminal. Unfortunately, the"interrupt execution" character,Escape, is used by some terminals forcursor control. Since Escape isdetected at a very low level in thesystem, there is no way to tailor thescreen editor to use these terminals.Unlike some LISP "structure" editorsthat use atoms and expressions as theunits to be modified, the muSTAReditor is a conventional character-oriented screen editor; however, it isconvenient and easy to use. Whenfunctions are being edited, the text ispretty-printed to make it easier toread and edit.

The Trace and Untrace facilities

allow the user to specify to themuSTAR system that when a givenfunction is called the system shouldprint its arguments before the execu-tion of the function and the resultafterward. This is the single most im-portant tool for the user in the pro-cess of debugging and developingprograms.

Read and Write are for text filesand assume a CP/M file extension of".LIB". The files can be created eitherby muSTAR or by an external editor.Read works in the obvious way.Write, however, writes out only func-

tions and variables whose names ap-pear on the property list of the atomthat is the name of the file. While thiscan be done using the Edit Propertyfunction of muSTAR, it is easy toforget to add new function namesduring a session and thus lose yourwork when you exit the muSTARsystem.

The error-handling facility inmuLISP is virtually nonexistent. Thethree "advisory" messages: ZERODIVIDE ERROR, END-OF-FILEREAD, and NO DISK SPACE areprinted at the console, and the

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offending primitive function is forcedto return NIL. Execution of the rest ofthe user function proceeds, accordingto the manual, "normally." The onlyerror that causes termination of ex-ecution is INSUFFICIENT MEMORYSPACE. When execution stops, aswhen the Escape key is typed, theuser has four options. He or she cancontinue execution, go back to thetop-level driver, restart muLISP, orgo back to the CP/M system. Unfor-tunately, the user cannot examine thefunctions or arguments that causedthe problem.

Because of the autOTquoting andimplicit-sequence-evaluation featuresof the system, there are no othererrors that can occur during programexecution. In fact, since evaluation ofany syntactically legal expression isdefined, and the input routines for thedriver loop ensure that only legal ex-pressions are read in, the user cannotcause any error other than the oneslisted above.

Although this may be an elegantconcept, it makes debuggingawkward at best and virtually im-possible at worst except for the Trace

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option available in muSTAR. Sincethis is not available in the coremuLISP system, you would alwaysdo development in muSTAR.

Cromemco LISP and (T.(L.C))LISP take a more traditional attitudeto the user environment and errorhandling. Errors are flagged in manysituations. In particular, the errorsUNDEFINED VARIABLE andWRONG NUMBER OF

ARGUMENTS, as well as data-typeviolations, are checked for duringprogram evaluation. The charactersG, Control-G, and Bell act like theEscape key in muLISP to end execu-tion of user functions. In addition,the function ERROR can be called bya function at any time.

Once an error occurs, evaiuationstops, a message is printed, and theuser has several options. He or shecan examine the function orarguments that caused the error, tracethe execution stack back through allthe nested calls, or "pop" up the stack(to the top or any intermediate place)giving a return value for the functionthat was called at that level.Although these functions are a goodidea, they are poorly explained in themanual.

Documentation, Library Software

We were very pleased with thequality of the documentation for allthree LISPs. Because Cromemco and(T.(L.C)) LISP are just different ver-sions of the same program, the twouser's manuals are almost identical.These manuals begin with a longdiscussion of LISP style andphilosophy and include a discussionof how to code a recursive descentparser in LISP. This background in-formation is quite good and will be agreat help to a beginner. Most of thefunction descriptions include an il-lustrative example. The CromemcoLISP manual adds a section on the in-ternal representation of data struc-tures and gives information needed tolink to assembly-languagesubroutines. The (T.(L.Q) LISPmanual includes some annotatedLISP examples adapted from Ar-tificial Intelligence Programming (seethe 'Where to Learn LISP" text boxfor a description of this book and

410 September 1981 © BYTE Publications Inc

Circle 81 on inquiry card.

other useful LISP information). Theseexamples are prefaced by a discussionof the differences between (T.(L.Q)LISP and the LISP used in ArtificialIntelligence Programming. We foundthis discussion quite useful. Bothmanuals are about 135 pages long.

The muLISP manual, which isabout 100 pages long, is shorter andterser, but of high quality. Thismanual gives a limited amount ofbackground information. The func-tion descriptions are in a formalmetalanguage that is complete butoften obscure. These descriptionswould be much clearer if they includ-ed examples. The manual includescommented listings of many usefulutilities and the muSTAR develop-ment environment, and they will bequite useful for users who wish totailor their LISP environment. In par-ticular, there are instructions fortailoring the muLISP screen editor todifferent kinds of terminals.

Cromemco LISP is distributed witha fairly complete set of Cromemcosoftware, including the CDOSoperating system, several CDOSutilities, and a screen editor. Unfor-tunately, the screen editor can onlybe used with a Cromemco terminal.This is downright unfriendly ofCromemco, particularly since it istrivial to provide the "hooks" to doscreen editing with almost anymodern terminal. Also provided arefiles with LISP utilities, a trace func-tion, a pretty-printer program, ex-amples from Artificial IntelligenceProgramming, and examples of themore esoteric features of CromemcoLISP.

(T.(L.C)) LISP is distributed withthe same example and utility files asCromemco LISP. Also included areseveral additional files of examples.

muLISP is distributed with themuSTAR utility and the other utilitiesdescribed in the manual. Also includ-ed are several games and programs,including a version of Weizenbaum'sELIZA, called DOCTOR, and aguessing game which learns, calledANIMAL.

muLISP has the beginnings of anactive user group and softwarelibrary. Information about the user

group and the software is publishedin a small newsletter available tomuLISP purchasers. (T.(L.C)) LISPpurchasers also receive a newsletter,though it is less formal and lessregular. As of now, there is no(T.(L.C)) LISP users' group.

Conclusions

• Cromemco and (T.(L.C)) LISP havemany modern features, yet they stillrun acceptably fast. The auto-loadfeature potentially allows very largeprograms to run in a virtual-memoryenvironment. The documentation is

quite good and would be useful forLISP beginners. Cromemco LISP alsoincludes information that would beuseful to someone adding his or herown machine-language subroutines.A major drawback of these LISPs is asmall, fixed-sized stack that severelylimits the use of recursive functions.(T.(L.Q) LISP is the cheapest of theLISPs reviewed here — $150.Cromemco LISP, with only a smallamount of additional functionality, isthe most expensive—$295.• muLISP is an extremely fast LISPwith a complete but basic set of

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features. It is distributed withmuSTAR, a nice LISP developmentenvironment that includes a screeneditor. The documentation is good,but it is too terse and formal forbeginners. Much of the speed ofmuLISP comes from features thatmake programs hard to read and hardto debug. In particular, muLISP doesalmost no type checking or errordetection.

• LISP is alive and well and living in aZ80 microprocessor. Although thereare great differences between muLISPand the other two packages, we feelthat all three are successful products.Each would allow a user to developand use fairly large LISP programs. ■

Acknowledgments

The benchmark tests were performed on asystem purchased and supported by ArmyResearch Office grant DAAG29-79-G-0046.We would like to thank E Jeffrey Conklin andCaxton C Foster,

Where to learn LISP:Recommended Books and Articles

1.Allen, J. Anatomy of LISP. NewYork: McGraw-Hill Book Co, 1978.An examination of many issues incomputer science through LISP-tintedspectacles. This is also the onlypublished discussion of many modernLISP implementation techniques andstyles.

2.Allen, J. "An Overview of LISP" inBYTE, August 1979, page 10. A com-pact overview to LISP style and usage.All the important LISP functions arediscussed. The most difficult aspect oflearning LISP is understanding exactlywhen and how values get bound tonames. These issues are not discussed.3.Charniak, Eugene, ChristopherRiesback, and Drew McDermott. Ar-tificial Intelligence Programming.Hillsdale NJ: Lawrence ErlbaumAssociates, 1979. A very complete in-troduction to sophisticated uses ofLISP for AI programming. The firstfew chapters do a good job of explain-ing the name-value-binding issues.

4.Friedman, Daniel. The Little LISPer.London, England: Science ResearchAssociates Inc, 1974. An entertainingintroduction to the style of LISP pro-gramming. This book does not covereverything you need to know to useLISP on a real machine. It, again,avoids key issues of how and whenLISP names get values.5.McCarthy, John. "Recursive Func-tions of Symbolic Expressions andTheir Computation by Machine,"Communications of the Associationfor Computing Machinery, pages 184through 195, April 1960. This is whereit all started, the article that suggestedthat the mathematical lambda calculuscould be embodied in a programminglanguage.

6.Winston, Patrick Henry. ArtificialIntelligence. Reading MA: Addison-Wesley, 1977. An easily understood in-troduction to AI and AI programming.7.Winston, Patrick Henry and Ber-thold Klaus Horn. LISP. Reading MA:Addison-Wesley, 1981. A pleasant,chatty introduction to LISP.

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BYTE's Bits

Microsoft DropsAPL Interpreter

Microsoft has dropped work on an APLinterpreter. The demand of other projectshas caused the company to stop work onthe interpreter for 8-bit microcomputers.The company still plans to develop a16-bit version.

BYTE's Bugs

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BYTE September 1981 413

The Emperor's Old Clothes

Charles Antony Richard HoareOxford University, England

The 1980 A CM Turing Award was pre-sented to Charles Antony Richard Hoare,Professor of Computation at OxfordUniversity, England, by Walter Carlson,chairman of the awards committee. Thepresentation took place at the ACM An-nual Conference in Nashville, Tennessee,October 27, 1980.

Professor Hoare was selected by theGeneral Technical Achievement AwardCommittee for his fundamental contribu-tions to the definition and design of pro-gramming languages. His work is charac-terized by an unusual combination of in-sight, originality, elegance, and impact.He is best known for his work on axio-matic definitions of programming lan-guages through the use of techniques pop-ularly referred to as axiomatic semantics.He developed ingenious algorithms suchas Quicksort and was responsible for in-venting and promulgating advanced data-structuring techniques in scientific pro-gramming languages. He has also madeimportant contributions to operating sys-tems through the study of monitors, andhis most recent work is on communicatingsequential processes.

Before his appointment to Oxford in1977, Professor Hoare was Professor ofComputer Science at The Queen's Univer-sity in Belfast, Ireland, from 1968 to 1977,and was a Visiting Professor at StanfordUniversity in 1973. From 1960 to 1968 he

Acknowledgments

BYTE wishes to thank Professor CAR Hoareand the Association for Computing Machineryfor granting us permission to reprint this arti-cle, which originally appeared in the February1981 Communications of the ACM. Copyright1981 by the Association for ComputingMachinery, Inc. Reprinted by permission.

Professor Charles Antony Richard Hoare

held a number of positions with ElliotBrothers Ltd, England.

Professor Hoare has published exten-sively and is on the editorial boards of anumber of the world's foremost computerscience journals. In 1973 he received theACM Programming Systems and Lan-guages Paper Award. Professor Hoarebecame a Distinguished Fellow of theBritish Computer Society in 1978 and wasawarded the degree of Doctor of ScienceHonoris Causa by the University ofSouthern California in 1979.

The Turing Award is the Associationfor Computing Machinery's highestaward for technical contributions to thecomputing community. It is presentedeach year in memory of Dr A M Turing,an English mathematician who mademany important contributions to the com-puting sciences.

A transcript of Professor Hoare s 1980Turing Award Lecture follows.

My first and most pleasant duty inthis lecture is to express my profoundgratitude to the Association for Com-puting Machinery for the great honorwhich they have bestowed on me andfor this opportunity to address youon a topic of my choice. What a dif-ficult choice it is I My scientificachievements, so amply recognizedby this award, have already beenamply described in the scientificliterature. Instead of repeating theabstruse technicalities of my trade, Iwould like to talk informally aboutmyself, my personal experiences, myhopes and fears, my modest suc-cesses, and my rather less modestfailures. I have learned more from myfailures than can ever be revealed inthe cold print of a scientific article,and now I would like you to learnfrom them, too. Besides, failures aremuch more fun to hear about after-wards; they are not so funny at thetime.

I start my story in August 1960,when I became a programmer with asmall computer manufacturer, a divi-sion of Elliott Brothers (London) Ltd,where in the next eight years I was toreceive my primary education incomputer science. My first task wasto implement for the new Elliot 803computer a library subroutine for anew fast method of internal sortingjust invented by Shell. I greatly en-joyed the challenge of maximizing ef-ficiency in the simple decimal-ad-

414 September 1981 © BYTE Publications Inc

dressed machine code of those days.My boss and tutor, Pat Shackleton,was very pleased with my completedprogram. I then said timidly that Ithought I had invented a sortingmethod that would usually run fasterthan SHELLSORT, without takingmuch extra store. He bet me sixpencethat I had not. Although my methodwas very difficult to explain, he final-ly agreed that I had won my bet.

I wrote several other tightly codedlibrary subroutines, but after sixmonths I was given a much more im-portant task—that of designing a newadvanced high-level programminglanguage for the company's next com-puter, the Elliott 503, which was to

have the same instruction code as theexisting 803 but run sixty times faster.In spite of my education in classicallanguages, this was a task for which Iwas even less qualified than thosewho undertake it today. By greatgood fortune there came into myhands a copy of the Report on the In-ternational Algorithmic LanguageALGOL 60. Of course, this languagewas obviously too complicated forour customers. How could they everunderstand all those begins and endswhen even our salesmen couldn't?

Around Easter 1961, a course onALGOL 60 was offered in Brighton,England, with Peter Naur, Edsger WDijkstra, and Peter Landin as tutors. I

attended this course with my col-league in the language project, JillPym, our divisional TechnicalManager, Roger Cook, and our SalesManager, Paul King. It was there thatI first learned about recursive proce-dures and saw how to program thesorting method which I had earlierfound such difficulty in explaining. Itwas there that I wrote the procedure,immodestly named Quicksort, onwhich my career as a computer scien-tist is founded. Due credit must bepaid to the genius of the designers ofALGOL 60 who included recursion intheir language and enabled me todescribe my invention so elegantly tothe world. I have regarded it as the

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highest goal of programming lan-guage design to enable good ideas tobe elegantly expressed.

After the ALGOL course inBrighton, Roger Cook was drivingme and my colleagues back to Lon-don when he suddenly asked, "In-stead of designing a new language,why don't we just implement ALGOL60?" We all instantly agreed—inretrospect, a very lucky decision forme. But we knew we did not have theskill or experience at that time toimplement the whole language, so Iwas commissioned to design a modestsubset. In that design I adopted cer-tain basic principles which I believe to

be as valid today as they were then.

Principles of Design

The first principle was security, theprinciple that every syntactically in-correct program should be rejected bythe compiler and that every syntac-tically correct program should give aresult or an error message that waspredictable and comprehensible interms of the source language programitself. Thus no core dumps shouldever be necessary. It was logically im-possible for any source language pro-gram to cause the computer to runwild, either at compile time or at runtime. A consequence of this principle

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is that every occurrence of every sub-script of every subscripted variablewas on every occasion checked at runtime against both the upper and thelower declared bounds of the array.Many years later we asked our cus-tomers whether they wished us toprovide an option to switch off thesechecks in the interests of efficiency onproduction runs. Unanimously, theyurged us not to—they already knewhow frequently subscript errors occuron production runs where failure todetect them could be disastrous. Inote with fear and horror that even in1980, language designers and usershave not learned this lesson. In anyrespectable branch of engineering,failure to observe such elementaryprecautions would have long beenagainst the law.

The second principle in the designof the implementation was brevity ofthe object code produced by the com-piler and compactness of run timeworking data. There was a clearreason for this: the size of main stor-age on any computer is limited, andits extension involves delay and ex-pense. A program exceeding the limit,even by one word, is impossible torun, especially since many of our cus-tomers did not intend to purchasebacking stores.

This principle of compactness ofobject code is even more valid today,when processors are trivially cheap incomparison with the amounts ofmain store they can address, andbacking stores are comparativelyeven more expensive and slower bymany orders of magnitude. If as aresult of care taken in implementationthe available hardware remains morepowerful than may seem necessaryfor a particular application, the appli-cations programmer can nearlyalways take advantage of the extracapacity to increase the quality of hisprogram, its simplicity, its rugged-ness, and its reliability.

The third principle of our designwas that the entry and exit conven-tions for procedures and functionsshould be as compact and efficient asfor tightly coded machine-code sub-routines. I reasoned that proceduresare one of the most powerful featuresof a high-level language, in that they

416 September 1981 © BYTE Publications Inc

Circle 280 on inquiry card.

both simplify the programming taskand shorten the object code. Thusthere must be no impediment to theirfrequent use.

The fourth principle was that thecompiler should use only a singlepass. The compiler was structured asa collection of mutually recursiveprocedures, each capable of analyz-ing and translating a major syntacticunit of the language—a statement, anexpression, a declaration, and so on.It was designed and documented inALGOL 60, and then coded into deci-mal machine code using an explicitstack for recursion. Without theALGOL 60 concept of recursion, atthat time highly controversial, wecould not have written this compilerat all.

I can still recommend single-pass,top-down recursive descent both asan implementation method and as adesign principle for a programminglanguage. First, we certainly wantprograms to be read by people, andpeople prefer to read things once in asingle pass. Second, for the user of atime-sharing or personal computersystem, the interval between typingin a program (or amendment) andstarting to run that program is whollyunproductive. It can be minimized bythe high speed of a single-pass com-piler. Finally, to structure a compileraccording to the syntax of its inputlanguage makes a great contributionto ensuring its correctness. Unless wehave absolute confidence in this, wecan never have confidence in the re-sults of any of our programs.

Principles at Work

To observe these four principles, Iselected a rather small subset ofALGOL 60. As the design and imple-mentation progressed, I graduallydiscovered methods of relaxing therestrictions without compromisingany of the principles. So in the end wewere able to implement nearly the fullpower of the whole language, includ-ing even recursion, although severalfeatures were removed and otherswere restricted.

In the middle of 1963, primarily asa result of the work of Jill Pym andJeff Hillmore, the first version of ourcompiler was delivered. After a few

months we began to wonder whetheranyone was using the language ortaking any notice of our occasionalreissue, incorporating improved op-erating methods. Only when acustomer had a complaint did he con-tact us, and many of them had nocomplaints. Our customers have nowmoved on to more modern computersand more fashionable languages, butmany have told me of their fondmemories of the Elliott ALGOL Sys-tem. The fondness is not due just tonostalgia, but to the efficiency, re-liability, and convenience of thatearly simple ALGOL System.

As a result of this work onALGOL, in August 1962 I was invitedto serve on the new Working Group2.1 of the International Federation ofInformation Processors (IFIP) chargedwith responsibility for maintenanceand development of ALGOL. Thegroup's first main task was to design asubset of the language which wouldremove some of its less successful fea-tures. Even in those days and evenwith such a simple language, we rec-ognized that a subset could be an im-provement on the original. I greatlywelcomed the chance of meeting andhearing the wisdom of many of theoriginal language designers. I wasastonished and dismayed at the heatand even rancor of their discussions.Apparently the original design ofALGOL 60 had not proceeded in thatspirit of dispassionate search for truthwhich the quality of the language hadled me to suppose.

In order to provide relief from thetedious and argumentative task of de-signing a subset, the working groupallocated one afternoon to discussingthe features that should be incor-porated in the next design of the lan-guage. Each member was invited tosuggest the improvement he consid-ered most important. On October 11,1963, my suggestion was to pass on arequest of our customers to relax theALGOL 60 rule of compulsory decla-ration of variable names and adoptsome reasonable default conventionsuch as that of FORTRAN. I wasastonished by the polite but firm re-jection of this seemingly innocentsuggestion. It was pointed out thatthe redundancy of ALGOL 60 was the

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best protection against programmingand coding errors which could be ex-tremely expensive to detect in a run-ning program and even more expen-sive not to. The story of the Marinerspace rocket to Venus, lost because ofthe lack of compulsory declarationsin FORTRAN, was not to be pub-lished until later. I was eventuallypersuaded of the need to design pro-gramming notations so as to max-imize the number of errors which can-not be made, or if made, can be re-liably detected at compile time.Perhaps this would make the text of

programs longer. Never mindlWouldn't you be delighted if yourFairy Godmother offered to wave herwand over your program to removeall its errors and only made the condi-tion that you should write out andkey in your whole program threetimes? The way to shorten programsis to use procedures, not to omit vitaldeclarative information.

Among the other proposals for thedevelopment of a new ALGOL wasthat the Switch declaration ofALGOL 60 should be replaced by amore general feature, namely an ar-

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ray of label-valued variables, andthat a program should be able tochange the values of these variablesby assignment. I was very much op-posed to this idea, similar to theassigned Go To of FORTRAN,because I had found a surprisingnumber of tricky problems in the im-plementation of even the simplelabels and switches of ALGOL 60. Icould see even more problems in thenew feature, including that of jump-ing back into a block after it had beenexited. I was also beginning to suspectthat programs that used a lot of labelswere more difficult to understand andget correct, and that programs thatassigned new values to label variableswould be even more difficult still.

It occurred to me that the appro-priate notation to replace the ALGOL60 switch should be based on that ofthe conditional expression of ALGOL60, which selects between two alter-native actions according to the valueof a Boolean expression. So I sug-gested the notation for a "case ex-pression" which selects between anynumber of alternatives according tothe value of an integer expression.That was my second language designproposal. I am still most proud of it,because it raises essentially no prob-lems either for the implementer, theprogrammer, or the reader of a pro-gram. Now, after more than fifteenyears, there is the prospect of interna-tional standardization of a languageincorporating this notation—a re-markably short interval comparedwith other branches of engineering.

Back again to my work at Elliott.After the unexpected success of ourALGOL Compiler, our thoughtsturned to a more ambitious project:to provide a range of operatingsystem software for larger configura-tions of the 503 computer, with cardreaders, line printers, magnetic tapes,and even a core backing store whichwas twice as cheap and twice as largeas the main store, but fifteen timesslower. This was to be known as theElliott 503 Mark II software system.It comprised:

1. An assembler for a symbolicassembly language in which all therest of the software was to be written.

2. A scheme for automatic ad-

418 September 1981 © BYTE Publications Inc

Circle 371 on inquiry card.

ministration of code and dataoverlays, either from magnetic tapeor from core backing store. This wasto be used by the rest of the software.

3. A scheme for automatic buffer-ing of all input and output on anyavailable peripheral device, again tobe used by all the other software.

4. A filing system on magnetictape with facilities for editing and jobcontrol.

5. A completely new implementa-tion of ALGOL 60, which removedall the nonstandard restrictions whichwe had imposed on our first im-plementation.

6. A compiler for FORTRAN as itwas then.

Deadline Pressures

I wrote documents which describedthe relevant concepts and facilities,and we sent them to existing and pro-spective customers. Work startedwith a team of fifteen programmers,and the deadline for delivery was setsome eighteen months ahead, inMarch 1965. After initiating thedesign of the Mark II software, I wassuddenly promoted to the dizzyingrank of Assistant Chief Engineer,responsible for advanced develop-ment and design of the company'sproducts, both hardware and soft-ware.

Although I was still manageriallyresponsible for the 503 Mark II soft-ware, I gave it less attention than thecompany's new products and almostfailed to notice when the deadline forits delivery passed without event. Theprogrammers revised their implemen-tation schedules, and a new deliverydate was set some three monthsahead, in June 1965. Needless to say,that day also passed without event.By this time, our customers were get-ting angry and my managers in-structed me to take personal charge ofthe project. I asked the senior pro-grammers once again to draw uprevised schedules, which againshowed that the software could bedelivered within another threemonths. I desperately wanted tobelieve it, but I just could not. Idisregarded the schedules and beganto dig more deeply into the project.

It turned out that we had failed to

make any overall plans for the alloca-tion of our most limited resource—main storage. Each programmer ex-pected this to be done automatically,either by the symbolic assembler orby the automatic overlay scheme.Even worse, we had failed to simplycount the space used by our own soft-ware which was already filling themain store of the computer, leavingno space for our customers to runtheir programs. Hardware addresslength limitations prohibited addingmore main storage.

Clearly, the original specificationsof the software could not be met andhad to be drastically curtailed. Ex-perienced programmers and evenmanagers were called back fromother projects. We decided to concen-trate first on delivery of the new com-piler for ALGOL 60, which carefulcalculation showed would takeanother four months. I impressedupon all the programmers involvedthat this was no longer just a predic-tion; it was a promise. If they foundthey were not meeting their promise,it was their personal responsibility tofind ways and means of makinggood.

The programmers respondedmagnificently to the challenge. Theyworked nights and days to ensurecompletion of all those items of soft-ware which were needed by theALGOL compiler. To our delight,they met the scheduled delivery date;it was the first major item of workingsoftware produced by the companyover a period of two years.

Our delight was short-lived; thecompiler could not be delivered. Itsspeed of compilation was only twocharacters per second, which com-pared unfavorably with the existingversion of the compiler operating atabout a thousand characters per sec-ond. We soon identified the cause ofthe problem: it was thrashing be-tween the main store and the exten-sion core backing store which was fif-teen times slower. It was easy tomake some simple improvements,and within a week we had doubledthe speed of compilation to four char-acters per second. In the next twoweeks of investigation and repro-gramming, the speed was doubled

again to eight characters per second.We could see ways in which within amonth this could be still further im-proved, but the amount of repro-gramming required was increasingand its effectiveness was decreasing;there was an awful long way to go.The alternative of increasing the sizeof the main store so frequentlyadopted in later failures of this kindwas prohibited by hardware address-ing limitations.

There was no escape: the entireElliott 503 Mark II software projecthad to be abandoned, and with it,over thirty man-years of program-ming effort, equivalent to nearly oneman's active working life. And I wasresponsible, both as designer and asmanager, for wasting it.

A meeting of all our 503 customerswas called and Roger Cook, who wasthen manager of the computing divi-sion, explained to them that not asingle word of the long-promisedsoftware would ever be delivered tothem. He adopted a very quiet tone ofdelivery, which ensured that none ofthe customers could interrupt, mur-mur in the background, or even shuf-fle in their seats. I admired but couldnot share his calm. Over lunch ourcustomers were kind to try to comfortme. They had realized long ago thatsoftware to the original specificationscould never have been delivered, andeven if it had been, they would nothave known how to use its sophisti-cated features, and anyway manysuch large projects get cancelledbefore delivery. In retrospect, Ibelieve our customers were fortunatethat hardware limitations had pro-tected them from the arbitrary ex-cesses of our software designs. In thepresent day, users of microprocessorsbenefit from a similar protection—but not for much longer.

At that time I was reading the earlydocuments describing the conceptsand features of the newly announcedOS 360, and of a new time-sharingproject called Multics. These were farmore comprehensive, elaborate, andsophisticated than anything I hadimagined, even in the first version ofthe 503 Mark II software. ClearlyIBM and MIT must be possessed ofsome secret of successful software de-

September 1981 © BYTE Publications Ire 419

sign and implementation whosenature I could not even begin to guessat. It was only later that they realizedthey could not either.

So I still could not see how I hadbrought such a great misfortune uponmy company. At the time I was con-vinced that my managers were plan-ning to dismiss me. But no, they wereintending a far more severe punish-ment. "OK, Tony," they said. "Yougot us into this mess, and now you'regoing to get us out."

"I don't know how," I protested,but their reply was simple. "Wellthen, you'll have to find out." Theyeven expressed confidence that Icould do so. I did not share their con-fidence. I was tempted to resign. Itwas the luckiest of all my luckyescapes that I did not.

Of course, the company did every-thing they could to help me. Theytook away my responsibility forhardware design and reduced the sizeof my programming teams. Each ofmy managers explained carefully hisown theory of what had gone wrong,and all the theories were different. Atlast, there breezed into my office themost senior manager of all, a generalmanager of our parent company, An-drew St. Johnston. I was surprisedthat he had even heard of me. "Youknow what went wrong?" he shouted(he always shouted). "You let yourprogrammers do things which youyourself do not understand." I staredin astonishment. He was obviouslyout of touch with present-dayrealities. How could one person everunderstand the whole of a modernsoftware product like the Elliott 503Mark II software system?

I realized later that he was ab-solutely right; he had diagnosed thetrue cause of the problem and he hadplanted the seed of its later solution.

Defining the Problems

I still had a team of some forty pro-grammers. We needed to retain thegoodwill of customers of our newmachine and even regain the con-fidence of the customers for our oldone. But what should we actuallyplan to do when we knew only onething—that all our previous plans

had failed? I therefore called an all-day meeting of our senior program-mers on October 22, 1965, to thrashout the question among us. I still havethe notes of that meeting. We firstlisted the recent major grievances ofour customers: cancellation of prod-ucts, failure to meet deadlines, ex-cessive size of software "not justifiedby the usefulness of the facilities pro-vided," excessively slow programs,failure to take account of customerfeedback. "Earlier attention paid toquite minor requests of our customersmight have paid as great dividends ofgoodwill as the success of our mostambitious plans," we concluded.

We then listed our own grievances:lack of machine time for programtesting, unpredictability of machinetime, lack of suitable peripheralequipment, unreliability of the hard-ware even when available, dispersionof programming staff, lack of equip-ment for keypunching of programs,lack of firm hardware delivery dates,lack of technical writing effort fordocumentation, lack of softwareknowledge outside the programminggroup, interference from highermanagers who imposed decisionswithout a full realization of the moreintricate implications of the matter,and overoptimism in the face ofpressure from customers and the salesdepartment.

But we did not seek to excuse ourfailure by these grievances. For exam-ple, we admitted that it was the dutyof programmers to educate theirmanagers and other departments ofthe company by presenting the neces-sary information in a simple palatableform. The hope "that deficiencies inoriginal program specifications couldbe made up by the skill of a technicalwriting department...was misguided.The design of a program and thedesign of its specification must beundertaken in parallel by the sameperson, and they must interact witheach other. A lack of clarity in speci-fication is one of the surest signs of adeficiency in the program it describes,and the two faults must be removedsimultaneously before the project isembarked upon." I wish I had fol-lowed this advice in 1963; I wish weall would follow it today.

My notes of the proceedings of thatday in October 1965 include a com-plete section devoted to failingswithin the software group; this sec-tion rivals the most abject self-abasement of a revisionist official inthe Chinese cultural revolution. Ourmain failure was overambition. "Thegoals which we have attempted haveobviously proved to be far beyondour grasp." There was also failure inprediction, in estimation of programsize and speed, of effort required, inplanning the coordination and in-teraction of programs, in providingan early warning that things were go-ing wrong. There were faults in ourcontrol of program changes, docu-mentation, liaison with other depart-ments, with our management, andwith our customers. We failed in giv-ing clear and stable definitions of theresponsibilities of individual pro-grammers and project leaders. Oh,need I go on? What was amazing wasthat a large team of highly intelligentprogrammers could labor so hard andso long on such an unpromising proj-ect. You know, you shouldn't trust usintelligent programmers. We canthink up such good arguments forconvincing ourselves and each otherof the utterly absurd. Especially don'tbelieve us when we promise to repeatan earlier success, only bigger andbetter next time.

The last section of our inquiry intothe failure dealt with the criteria ofquality of software. "In the recentstruggle to deliver any software at all,the first casualty has been considera-tion of the quality of the softwaredelivered. The quality of software ismeasured by a number of totally in-compatible criteria, which must becarefully balanced in the design andimplementation of every program."We then made a list of no less thanseventeen criteria which has beenpublished in a guest editorial inVolume 2 of the journal SoftwarePractice and Experience.

Recovery Period

How did we recover from thecatastrophe? First, we classified our503 customers into groups, accordingto the nature and the size of the hard-

420 September 1981 © BYTE Publications Inc

ware configurations which they hadbought. For example, those withmagnetic tapes were all in one group.We assigned to each group of custom-ers a small team of programmers andtold the team leader to visit thecustomers to find out what theywanted, to select the easiest request tofulfill, and to make plans (but notpromises) to implement it. In no casewould we consider a request for afeature that would take more thanthree months to implement and de-liver. The project leader would thenhave to convince me that thecustomer's request was reasonable,that the design of the new feature wasappropriate, and that the plans andschedules for implementation wererealistic. Above all, I did not allowanything to be done which I did notmyself understand. It worked I Thesoftware requested began to bedelivered on the promised dates.With an increase in our confidenceand that of our customers, we wereable to undertake fulfilling slightlymore ambitious requests. Within ayear, we had recovered from thedisaster. Within two years, we evenhad some moderately satisfiedcustomers.

Thus we muddled through by com-mon sense and compromise to some-thing aproaching success. But I wasnot satisfied. I did not see why thedesign and implementation of an op-erating system should be so muchmore difficult than that of a compiler.This is the reason why I have devotedmy later research to problems ofparallel programming and languageconstructs which would assist in clearstructuring of operating systems—constructs such as monitors and com-municating processes.

While I was working at Elliott, Ibecame very interested in techniquesfor formal definition of programminglanguages. At that time, Peter Landinand Christopher Strachey proposedto define a programming language ina simple functional notation thatspecified the effect of each commandon a mathematically defined abstractmachine. I was not happy with thisproposal because I felt that such adefinition must incorporate a numberof fairly arbitrary representation

decisions and would not be muchsimpler in principle than an imple-mentation of the language for a realmachine. As an alternative, I pro-posed that a programming languagedefinition should be formalized as aset of axioms, describing the desiredproperties of programs written in thelanguage. I felt that carefully formu-lated axioms would leave an imple-mentation the necessary freedom toimplement the language efficiently ondifferent machines and enable theprogrammer to prove the correctnessof his programs.

But I did not see how to actually doit. I thought that it would needlengthy research to develop andapply the necessary techniques, andthat a university would be a betterplace to conduct such research thanindustry. So I applied for a chair inComputer Science at the Queen'sUniversity of Belfast, where I was tospend nine happy and productiveyears. In October 1968, as I unpackedmy papers in my new home in Bel-fast, I came across an obscure reprint

of an article by Bob Floyd entitled,"Assigning Meanings to Programs."What a stroke of luck! At last I couldsee a way to achieve my hopes for myresearch. Thus I wrote my first paperon the axiomatic approach to com-puter programming, published in theCommunications of the ACM inOctober 1969.

Just recently, I have discoveredthat an early advocate of the asser-tional method of program provingwas none other than Alan Turinghimself. On June 24, 1950, at a con-ference in Cambridge, he gave a shorttalk entitled, "Checking a Large Rou-tine," which explains the idea withgreat clarity. "How can one check alarge routine in the sense of makingsure that it's right?" Turing asked. "Inorder that the man who checks maynot have too difficult a task, the pro-grammer should make a number ofdefinite assertions which can bechecked individually, and fromwhich the correctness 'of the wholeprogram easily follows."

Consider the analogy of checking

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an addition. If the sum is given as acolumn of figures with the answerbelow, one must check the whole atone sitting. But if the totals for thevarious columns are given with thecarries added in separately, thechecker's work is much easier, beingsplit up into the checking of thevarious assertions (that each columnis correctly added) and the small ad-dition (of the carries to the total).This principle can be applied to thechecking of a large routine, but wewill illustrate the method by means ofa small routine: one to obtain n fac-torial without the use of a multiplier.Unfortunately, there is no codingsystem sufficiently generally knownto justify giving this routine in full,but a flow diagram will be sufficientfor illustration. That brings me backto the main theme of my talk, thedesign of programming languages.

During the period August 1962 toOctober 1966, I attended everymeeting of the IFIP ALGOL workinggroup. After completing our laborson the IFIP ALGOL subset, westarted on the design of ALGOL X,the intended successor to ALGOL 60.More suggestions for new featureswere made and in May 1965, NiklausWirth was commissioned to collatethem into a single language design. Iwas delighted by his draft design,which avoided all the known defectsof ALGOL 60 and included severalnew features, all of which could besimply and efficiently implemented,and safely and conveniently used.

The description of the languagewas not yet complete. I worked hard

on making suggestions for its im-provement, and so did many othermembers of our group. By the time ofthe next meeting in St. Pierre deChartreuse, France, in October 1965,we had a draft of an excellent andrealistic language design which waspublished in June 1966 as "A Con-tribution to the Development ofALGOL" in Communications of theACM. It was implemented on theIBM 360 and given the title ALGOLW by its many happy users. It wasnot only a worthy successor ofALGOL 60, it was even a worthypredecessor of Pascal.

At the same meeting, the ALGOLcommittee had placed before it ashort, incomplete and rather incom-prehensible document describing adifferent, more ambitious and, to me,a far less attractive language. I wasastonished when the working group,consisting of all the best known inter-national experts of programming lan-guages, resolved to lay aside the com-missioned draft on which we had allbeen working and swallow a line withsuch an unattractive bait.

Two Design Paths

This happened just one week afterour inquest on the 503 Mark II soft-ware project. I gave desperate warn-ings against the obscurity, the com-plexity, and overambition of the newdesign, but my warnings went un-heeded. I conclude that there are twoways of constructing a software de-sign: One way is to make it so simplethat there are obviously no deficien-cies, and the other way is to make it

so complicated that there are no ob-vious deficiencies.

The first method is far more dif-ficult. It demands the same skill,devotion, insight, and even inspira-tion as the discovery of the simplephysical laws which underlie thecomplex phenomena of nature. It alsorequires a willingness to accept objec-tives which are limited by physical,logical, and technological con-straints, and to accept a compromisewhen conflicting objectives cannot bemet. No committee will ever do thisuntil it is too late.

So it was with the ALGOL commit-tee. Clearly the draft which it pre-ferred was not yet perfect. So a newand final draft of the new ALGOLlanguage design was promised inthree months' time; it was to be sub-mitted to the scrutiny of a subgroupof four members including myself.Three months came and went, with-out a word of the new draft. After sixmonths, the subgroup met in theNetherlands. We had before us alonger and thicker document, full oferrors corrected at the last minute,describing yet another but to me,equally unattractive language.Niklaus Wirth and I spent some timetrying to get removed some of thedeficiencies in the design and in thedescription, but in vain. The com-pleted final draft of the language waspromised for the next meeting of thefull ALGOL committee in threemonths' time.

Three months came and went—nota word of the new draft appeared.After six months, in October 1966,

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the ALGOL working group met inWarsaw. It had before it an evenlonger and thicker document, full oferrors corrected at the last minute,describing equally obscurely yetanother different, and to me, equallyunattractive language. The experts inthe group could not see the defects ofthe design and they firmly resolved toadopt the draft, believing it would becompleted in three months. In vain, Itold them it would not. In vain, Iurged them to remove some of thetechnical mistakes of the language,the predominance of references, thedefault type conversions. Far fromwishing to simplify the language, theworking group actually asked theauthors to include even more com-plex features like overloading ofoperators and concurrency.

When any new language designproject is nearing completion, there isalways a mad rush to get new featuresadded before standardization. Therush is mad indeed, because it leadsinto a trap from which there is noescape. A feature which is omittedcan always be added later, when itsdesign and its implications are wellunderstood. A feature which is in-cluded before it is fully understoodcan never be removed later.

At last, in December 1968, in amood of black depression, I attendedthe meeting in Munich at which ourlong-gestated monster was to come tobirth and receive the name ALGOL68. By this time, a number of othermembers of the group had becomedisillusioned, but too late: the com-mittee was now packed with sup-porters of the language, which wassent up for promulgation by thehigher committees of IFIP. The bestwe could do was to send with it aminority report, stating our con-sidered view that "...as a tool for thereliable creation of sophisticated pro-grams, the language is a failure." Thisreport was later suppressed by IFIP,an act which reminds me of the linesof Hilaire Belloc:

But scientists, who ought to knowAssure us that it must be so.Oh, let us never, never doubtWhat nobody is sure about.

I did not attend any furthermeetings of that working group. I ampleased to report that the group sooncame to realize that there was some-thing wrong with their language andwith its description; they laboredhard for six more years to produce arevised description of the language. Itis a great improvement but I'm afraidthat, in my view, it does not removethe basic technical flaws in the design,nor does it begin to address the prob-lem of its overwhelming complexity.

Programmers are always surround-ed by complexity; we cannot avoid it.Our applications are complex becausewe are ambitious to use our com-puters in ever more sophisticatedways. Programming is complexbecause of the large number of con-flicting objectives for each of our pro-gramming projects. If our basic tool,the language in which we design andcode our programs, is also com-plicated, the language itself becomespart of the problem rather than partof its solution.

Another Project

Now let me tell you about yetanother overambitious languageproject. Between 1965 and 1970 I wasa member and even chairman of theTechnical Committee No. 10 of theEuropean Computer ManufacturersAssociation. We were charged firstwith a watching brief and then withthe standardization of a language toend all languages, designed to meetthe needs of all computer applica-tions, both commercial and scientific,by the greatest computer manufac-turer of all time. I had studied withinterest and amazement, even a touchof amusement, the four initial docu-ments describing a language calledNPL, which appeared between March1 and November 30, 1964. Each wasmore ambitious and absurd than thelast in its wishful speculations. Thenthe language began to be imple-mented and a new series of docu-ments began to appear at six-monthlyintervals, each describing the finalfrozen version of the language, underits final frozen name PL/I.

But to me, each revision of the doc-

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ument simply showed how far the ini-tial F-level implementation had pro-gressed. Those parts of the languagethat were not yet implemented werestill described in free-flowing floweryprose giving promise of unalloyeddelight. In the parts that had been im-plemented, the flowers had withered;they were choked by an undergrowthof explanatory footnotes, placing ar-bitrary and unpleasant restrictions onthe use of each feature and loadingupon a programmer the responsibilityfor controlling the complex and unex-pected side-effects and interaction ef-fects with all the other features of thelanguage.

At last, March 11, 1968, the lan-guage description was nobly pre-sented to the waiting world as aworthy candidate for standardiza-tion. But it was not. It had alreadyundergone some seven thousand cor-rections and modifications at thehand of its original designers.Another twelve editions were neededbefore it was finally published as astandard in 1976. I fear that this wasnot because everybody concernedwas satisfied with its design, butbecause they were thoroughly boredand disillusioned.

For as long as I was involved in thisproject, I urged that the language besimplified, if necessary by subsetting,so that the professional programmerwould be able to understand it and beable to take responsibility for the cor-rectness and cost-effectiveness of hisprograms. I urged that the dangerousfeatures such as defaults and on con-ditions be removed. I knew that itwould be impossible to write awholly reliable compiler for a lan-guage of this complexity, and impos-sible to write a wholly reliable pro-gram when the correctness of eachpart of the program depends onchecking that every other part of theprogram has avoided all the traps andpitfalls of the language.

At first I hoped that such a tech-nically unsound project would col-lapse, but I soon realized it wasdoomed to success. Almost anythingin software can be implemented, sold,and even used given enough determi-nation. There is nothing a mere scien-tist can say that will stand against the

flood of a hundred million dollars.But there is one quality that cannot bepurchased in this way—and that isreliability. The price of reliability isthe pursuit of the utmost simplicity. Itis a price which the very rich findmost hard to pay.

All this happened a long time ago.Can it be regarded as relevant in aconference dedicated to a preview ofthe Computer Age that lies ahead? Itis my gravest fear that it can. The

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mistakes which have made in the lasttwenty years are being repeated to-day on an even grander scale. I referto a language design project whichhas generated documents entitledstrawman, woodenman, tinman,ironman, steelman, green and finallynow Ada. This project has been ini-tiated and sponsored by one of theworld's most powerful organizations,the United States Department of De-fense. Thus it is ensured of an in-fluence and attention quite indepen-dent of its technical merits, and itsfaults and deficiencies threaten uswith far greater dangers. For none ofthe evidence we have so far can in-spire confidence that this languagehas avoided any of the problems thathave afflicted other complex languageprojects of the past.

I have been giving the best of myadvice to this project since 1975. Atfirst I was extremely hopeful. Theoriginal objectives of the language in-cluded reliability, readability of pro-grams, formality of language defini-tion, and even simplicity. Graduallythese objectives have been sacrificedin favor of power, supposedlyachieved by a plethora of featuresand notational conventions, many ofthem unnecessary and some of them,like exceptions handling, evendangerous. We relive the history ofthe design of the motor car. Gadgetsand glitter prevail over fundamentalconcerns of safety and economy.

It is not too latel I believe that bycareful pruning of the Ada language,it is still possible to select a verypowerful subset that would bereliable and efficient in implementa-tion and safe and economic in use.The sponsors of the language havedeclared unequivocally, however,that there shall be no subsets. This isthe strangest paradox of the wholestrange project. If you want a lan-guage with no subsets, you mustmake it small.

You include only those featureswhich you know to be needed forevery single application of the lan-guage and which you know to be ap-propriate for every single hardwareconfiguration on which the languageis implemented. Then extensions canbe specially designed where necessaryfor particular hardware devices andfor particular applications. That isthe great strength of Pascal, that thereare so few unnecessary features andalmost no need for subsets. That iswhy the language is strong enough tosupport specialized extensions—con-current Pascal for real-time work,Pascal Plus for discrete event simula-tion, UCSD Pascal for micropro-cessor work stations. If only we couldlearn the right lessons from the suc-cesses of the past, we would not needto learn from our failures.

And so, the best of my advice tothe originators and designers of Adahas been ignored. In this last resort, Iappeal to you, representatives of theprogramming profession in theUnited States, and citizens concernedwith the welfare and safety of yourown country and of mankind: do notallow this language in its present stateto be used in applications wherereliability is critical, ie, nuclear powerstations, cruise missiles, early warn-ing systems, anti-ballistic missiledefense systems. The next rocket togo astray as a result of a program-ming language error may not be anexploratory space rocket on aharmless trip to Venus. It may be anuclear warhead exploding over oneof our own cities. An unreliableprogramming language generatingunreliable programs constitutes a fargreater risk to our environment andto our society than unsafe cars, toxic

424 September 1981 © BYTE Publicalions Inc

pesticides, or accidents at nuclearpower stations. Be vigilant to reducethat risk, not to increase it.

Let me not end on this sombernote. To have our best advice ignoredis the common fate of all who take onthe role of consultant, ever sinceCassandra pointed out the dangers ofbringing a wooden horse within thewalls of Troy. That reminds me of astory I used to hear in my childhood.

The Emperor's Old Clothes

Many years ago, there was anEmperor who was so excessively fondof clothes that he spent all his moneyon dress. He did not trouble himselfwith soldiers, attend banquets, orgive judgment in court. Of any otherking or emperor one might say, "He issitting in council," but it was alwayssaid of him, "The emperor is sitting inhis wardrobe." And so he was. Onone unfortunate occasion, he hadbeen tricked into going forth naked tohis chagrin and the glee of his sub-jects. He resolved never to leave histhrone, and to avoid nakedness, heordered that each of his many newsuits of clothes should be simplydraped on top of the old.

Time passed away merrily in thelarge town that was his capital.Ministers and courtiers, weavers andtailors, visitors and subjects,seamstresses and embroiderers, wentin and out of the throne room abouttheir various tasks, and they all ex-claimed, "How magnificent is the at-tire of our Emperor."

One day the Emperor's oldest andmost faithful minister heard tell of amost distinguished tailor who taughtat an ancient institute of higher stitch-craft, and who had developed a newart of abstract embroidery usingstitches so refined that no one couldtell whether they were actually thereat all. "These must indeed be splendidstitches," thought the minister. "If wecan but engage this tailor to adviseus, we will bring the adornment ofour Emperor to such heights of osten-tation that all the world willacknowledge him as the greatestEmperor there has ever been."

So the honest old minister engaged

the master tailor at vast expense. Thetailor was brought to the throneroom, where he made obeisance tothe heap of fine clothes which nowcompletely covered the throne. Allthe courtiers waited eagerly for hisadvice. Imagine their astonishmentwhen his advice was not to addsophistication and more intricate em-broidery to that which already ex-isted, but rather to remove layers ofthe finery, and strive for simplicityand elegance in place of extravagantelaboration.

"This tailor is not the expert that heclaims," they muttered. "His witshave been addled by long contempla-tion in his ivory tower, and he nolonger understands the sartorial needsof a modern Emperor." The tailorargued loud and long for the goodsense of his advice but could notmake himself heard. Finally, he ac-cepted his fee and returned to hisivory tower.

Never to this day has the full truthof this story been told: that one finemorning, when the Emperor felt hotand bored, he extricated himself care-fully from under his mountain ofclothes and is now living happily as aswineherd in another story. Thetailor is canonized as the patron saintof all consultants, because in spite ofthe enormous fees that he extracted,he was never able to convince hisclients of his dawning realization thattheir clothes have no Emperor. ■

BYTE's Bits

TransplantedApple Shoppe

Joesph L Rollinson is the new publisherof The Apple Shoppe Magazine. AppleShoppe, which describes itself as the"journal of Apple applications," is aperiodical for users of Apple II and IIIcomputers. The magazine was previouslypublished by David Smith of Placentia,California. Mr Rollinson is a native of SanDiego, California.

Apple Shoppe is published eight times ayear, for a subscriber's cost of $12 in theUnited States. Contact The Apple ShoppeMagazine, POB 22026, San Diego CA92122. ■

Circle 172 on inquiry card.

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PERIPHERALS: The ENSIGN supports the tapeand Winchester disk family from Kennedy Co.These drives, tape cartridges, and 9 track tapedrives are the premier of the industry. Yet pricesare low on the ENSIGN.

SOFTWARE: If you are running MP/M, OASIS, orMVT-FAMOS you will run better on an ENSIGN.And if you're not already tied to one of thesesystems you may want to try IBC-SUPERDOS.SUPERDOS is very powerful and very very fast.

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September 1981 © BYTE Publications Inc 425

Technical Forum

Microcomputersand the IRS

James C Kingman, Chief, Examination Section

Helena International Revenue Service District

Helena MT 59601

Although the author is an employee of the Internal Revenue Service, thecontent of this article is his opinion and does not necessarily reflect theposition of the United States Internal Revenue Service....SM

The 1980s will see unprecedented growth in the use ofmicrocomputers by small independent businesses andprofessional persons. With great potential for fast, ac-curate processing of accounting data and other types ofbusiness records at a minimal cost, microcomputers, likephotocopying machines, will soon be standard equip-ment in most offices.

Microcomputers offer a means of simplifying record-keeping systems while producing more timely, accurate,and detailed reports than were ever possible using amanual accounting system. The greatest benefit to asmall business or professional person, however, is thecost. For a cost comparable to the annual salary of abookkeeper, the individual can purchase a hardware andsoftware system capable of many times the work outputof a single person. If the system is well planned and prop-erly implemented, it can result in an overall cost savingsand a significant increase in the usefulness and efficiencyof the record-keeping system.

Traditionally, a person entering a new business workswith his accountant to set up a record-keeping systemthat meets generally accepted accounting principles andpractices. These systems provide a logical method of trac-ing detailed records such as invoices and vouchersthrough the accounting process to the final financialreports. The systems usually produce a general ledgerwhich is supported by subsidiary ledgers or such journalsas Accounts Receivable and Accounts Payable. These, inturn, provide a complete listing of the detailed records.Thus, with the traditional method it is possible to tracean individual detailed record through the entire system.This system of tracking records is known as the 'AuditTrail."

As more and more business and professional people ac-quire and learn to program their microcomputer systems,there may be a temptation to simplify record-keeping sys-tems to the point where the Audit Trail is lost. For exam-ple, an individual might be tempted to write a programthat would simply require the input of detailed records

and would produce completed financial statements asoutput. While such a program would be very simple towrite and even simpler to operate, it would completelyeliminate any form of Audit Trail.The lack of an Audit Trail creates two major problems:First, any error or discrepancy on the original detailedrecord would be impossible to locate without a completereconstruction of all detailed records. Suppose you hadsuch a simplified program for your Accounts Receivable.Each day, week, or month you would key in new chargesand payments on account. At the end of the period yoursimple system would produce a statement for each cus-tomer, without any reference to the original detailedrecords. Such a program might work well as long as noerrors were made in entering the detailed records. Whatwould happen, however, if one of your customers paid$50 on his account and you recorded $5? Without a refer-ence to any records, you would need to manually recon-struct the customer's entire account to verify whether ornot he had, in fact, paid $50. Not only would the processbe time-consuming—it would create a relation problemwith the customer because of the original error.

The second problem with such a program is that it isunacceptable to the Internal Revenue Service. Section6001 of the Internal Revenue Code of 1954 requires, inpart, that "every person liable for any tax imposed bythis title, or for the collection thereof, shall keep suchrecords, render such statements, make such returns andcomply with such rules and regulations as the Secretarymay from time to time prescribe." Under the authority ofthis code section, the Internal Revenue Service has issuedRevenue Procedure 64-12 (Cumulative Bulletin 1964-1,Part 1, page 672), which defines "guidelines for record re-quirements to be followed in cases where part or all of theaccount records are maintained within automatic dataprocessing systems." The Internal Revenue Service hasalso issued Revenue Ruling 71-20 (Cumulative Bulletin1971-1, page 392), which holds that "punched cards,magnetic tapes, disks, and other machine-sensible datamedia used in the automatic data processing of account-ing transactions constitute records within the meaning ofsection 1.6001-1 of the regulations." Let us see how thisRevenue Procedure and Revenue Ruling affect the busi-

426 September 1981 © BYTE Publications Inc

ness or professional person using a microcomputer in hisbusiness.

Revenue Procedure 64-12 deals directly with the needfor an Audit Trail in an accounting system. Section 1.01of the Revenue Procedure states its purpose:

Section 1. Purpose

.01 The purpose of this Revenue Procedure is to setforth guidelines specifying the basic record re-quirements which the Internal Revenue Serviceconsiders to be essential in cases where ataxpayer's records are maintained within an auto-matic data processing (ADP) system. Referenceshere to ADP systems include all accounting sys-tems which process all or part of a taxpayer'stransactions, records, or data by other thanmanual methods.

Section 3 states the objectives of the Revenue Pro-cedures:

Section 3. Objectives

.... The ability to provide in legible form the datanecessary to determine at a later date whether ornot the correct tax liability has been reported mustbe carefully considered in designing and program-ming a machine system. This factor may add tothe complexity of the system and require addi-tional cost, but this cost may be negligible in com-parison to the expense that may be incurred at alater date if the system cannot practically andreadily provide the information needed to supportand substantiate the accuracy of the previouslyreported tax liability.

(Emphasis supplied.)

Section 4 gives the specific record requirements that theInternal Revenue Service considers essential in any ADPaccounting system:

Section 4. ADP Record Guidelines

.01 ...A computer's accounting program must includea method of producing from the punched cards ortapes visible and legible records which will pro-vide the necessary information for the verificationof the taxpayer's tax liability.

.02 General and Subsidiary Books of Account.—A

(1) general ledger, with source references, should bewritten out to coincide with financial reports fortax reporting periods. In cases where subsidiaryledgers are used to support the general ledger ac-counts, the subsidiary ledgers should also be writ-ten out periodically.

(2) Supporting Documents and Audit Trail. — Theaudit trail should be designed so that the detailsunderlying the summary accounting data, such asinvoices and vouchers, may be identified andmade available to the Internal Revenue Serviceupon request.

(3) Recorded or Reconstructible Data.— The recordsmust provide the opportunity to trace any trans-action back to the original source or forward to afinal total. If printouts are not made of transac-tions at the time they are processed, then thesystem must have the ability to reconstruct thesetransactions.

Revenue Ruling 71-20 clarifies the term "records" asused in Code Section 6001:

...At is held that punched cards, magnetic tapes,disks, and other machine-sensible data media usedfor recording, consolidating, and summarizing ac-counting transactions and records within a tax-payer's automatic data processing system arerecords within the meaning of section 6001 of theCode and section 1.6001-1 of the regulations andare required to be retained so long as the contentsmay become material in the administration of anyinternal revenue law...

Both the Revenue Procedure and the Revenue Rulingare well known to most large companies using computersystems in their accounting process, but they may not beas well known to the small business using mini- andmicrocomputer systems. These businesses should checkthe following items in order to be sure their systems meetthe requirements of the Internal Revenue Service:

• Any system or program should preserve the in-tegrity of the Audit Trail so that any summarytotal may be traced back to the original detailedrecords, and any detailed record may be tracedforward to the summary total.

• If the system or program does not produce print-outs of the detailed transactions as they are pro-cessed, then the system or program must have theability to reconstruct these transactions at the re-quest of the Internal Revenue Service.

• If the system or program maintains accountingrecords on machine-sensible data media, suchmedia are considered records and must be main-tained for the same period of time as a hard-copyprintout.

• Finally, if the system or program does maintainsuch machine-sensible data media, the system orprogram must include a method of producing visi-ble and legible printouts of the media.

This article may raise more questions than it hasanswered. What should you do if you have questionsabout your system? A final quote from Revenue Ruling71-20:

...taxpayers who are in doubt as to which recordsare to be retained or who desire further informa-tion should contact their District Director forassistance. ■

September 1981 © BYTE Publications Inc 427

Technical Forum

Add Dual Trace and Delayed Sweepto Your Oscilloscope

Robert J Stetson, BASF SystemsCrosby Dr, Bedford MA 01730

Occasionally the need arises to make timing com-parisons between two signals with an interval delay.However, with a conventional oscilloscope you cannotscan a looped serial-data exchange with the clock inregistration and still look at the data that occurs 40 byteslater. In this situation, you may want to build an add-onunit that converts your present single-channel scope to adigital dual-trace scope with delayed sweep for about$15.

Theory of Operation—Data Multiplexer

Figures 1 and 2 show the complete logic diagram of theunit. Figure 2 is a simple, stable, clock circuit. A chop-ping frequency of 1 F CLK was selected, since it is com-mon among dual-trace scopes. The 555 integrated circuitis used as a free-running timer that generates 2 F CLK.Since the output of the 555 is highly asymmetrical, it runsat twice the desired rate, and 2 F CLK is fed to the inputof a 74LS74-type D edge flip-flop. The 74LS74 is wired asa divider and neatly converts the pulse train from the 555timer into a perfectly symmetrical square wave of half thefrequency of 2 F CLK. It is important that 1 F CLK besymmetrical to insure that the two traces have the samerelative brightness. This brightness is a direct function ofthe sample time (controlled by 1 F CLK) for each channel.

In figure 1, 1 F CLK enables the channel 1 NAND gate(74LS00) when high, and enables the channel 2 NANDgate (74LS00) through a 74LS04 inverter when low. Thetwo channels are multiplexed into a single signal on pin11 of the 74LS00, an active low NOR gate.

Vertical separation of the traces can best be understoodby walking through the circuit with 0V input to bothchannels. If both inputs stay at a low level, the output onpin 11 of the 74LS00 NOR gate stays low. Even thoughthere is no signal, the output signal, SCOPE, will switchat 1 F CLK speed.

The diagrams in figure 4 show the relationship betweenthe 100 k-ohm 1 F CLK leg of the summing network andthe 150 k-ohm DATA leg. With 1 F CLK in a low logicstate, the DATA input selects one of the two possiblezones in the channel 2 area of the screen. With 1 F CLKhigh, the DATA input selects one of the two channel 1areas of the screen:

Where DATA is low, DATA = 0 VWhere 1 F CLK is low, 1 F CLK = 0 V

Where DATA is high, DATA - 2 VWhere 1 F CLK is high, 1 F CLK « 3 V

The output from the summing network is one of the fourpossible combinations:

low + low = channel 2 low 0 + 0 = 0 Vlow + high = channel 2 high 0 + 1 = 2 Vhigh + low = channel 1 low 1 + 0 = 3 Vhigh + high = channel 1 high 1 + 1 = 5 V

Even though half of the oscilloscope display time isspent on the upper area of the screen and half on thelower, the traces appear as two solid lines, because the 1 FCLK is synchronized with the two channel inputs, but notwith the scope. The chopping frequency free-runs withrelationship to the horizontal-sweep frequency of thescope, which is synchronized only with the signal at theinput to channel 1.

Any attempt to synchronize on the signal at the multi-plexer's SCOPE output will fail. The multiplexing actiononly allows you to synchronize on 1 F CLK; otherwise, asthe two channels of data race across the screen they willbe out of synchronization with the horizontal oscillatorin the scope. A sample of the signal on which you want tosynchronize is taken from the channel 1 input before itgets chopped by the multiplexer. This signal is thencoupled by the trigger-control circuit to the scope's SYNCor TRIGGER input.

Trigger Control Circuit Theory

When INT (internal trigger) is used, the channel 1probe should always be on the signal from which youwant to synchronize. The 74LS04 inverter at the channel1 input buffers the input signal so that the circuit beingsampled does not see the added load of the extra cir-cuitry. The second 74LS04 reinverts the signal to its truepolarity.

Inverters are placed in the channel 2 signal path tobalance the gate delays between the two channels. Thisensures accurate results, regardless of the quality of thescope.

Another 74LS04 inverter gates the signal over to aswitch where either NORMAL trigger mode orDELAYED SWEEP is selected.

With the MODE switch in the NORM position, the

428 September 1981 © BYTE Publications Inc

sv

A

f

RANGE

X

,0.01/iF ^-TNO.l/iF

;i/tF

VERNIER

10K

POT

I

,_ I

EXT I

^"^

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SLOPE

10

■IK

;o.l^F

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B

74LS121Al Q

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11

LS7404

LS7400

LS7404

H \_6 9 8 13 d J3—1

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-* • l^ LS7400 <,

JfZ^ . LS7404 DATALEg4

1. v " ©

- N 3 IF CLOCK LEG-* T

L _°y |iook

50KDATA LEG*! SC0PE

LS7400

-o

IFCLOCK

Figure 1: Multiplex interface schematic for adding dual trace and delayed sweep to an oscilloscope. See text for details on how thecircuit works.

trigger signal is switched straight through to the 74LS04inverter, which drives the 2N2222 transistor output-driver.

The TRIGG output is monitored by the couplingcapacitor, which sets off the trigger timer and lights thetrigger LED (light-emitting diode). The 74LS74 drivingthe trigger LED acts as an inverter: with its_preset andclear inputs both low, the output on Q and Q are high.But, when the clear input goes high, the output Q goeslow. In this way, the Q output will always be the inverseof the clear input, while the Q output remains high at alltimes. As long as the trigger LED remains lit, the scope isbeing triggered.

With the MODE in the DELAY position, the triggerpulses are routed through the SLOPE switch. The SLOPEswitch directs the pulse to either the A or B input of a74L121 monostable multivibrator.

I chose a 74L121 over other multivibrators because it isnot retriggerable. While a 74LS123 would reduce theparts count, recurring triggers would extend the delaytime indefinitely.

By using the RANGE and VERNIER controls, you canadjust the delay time. These controls increase or decreasethe time from the selected edge of the triggering pulse to

the timeout of the first stage of the timer chain. The sec-ond 74L121 fires when the first one times out. The secondemits a short spike from which to trigger the scope.

An additional feature, the SOURCE switch, allows youto trigger from an independent source. This may be an in-dex pulse, sector pulses or other reference signals fromequipment you are working on.

Mastering the use of this unit requires patience. For in-stance, the channel 1 trigger source can be used only incertain applications. Other applications are best servedby the external trigger option. Under certain conditionsduring the delayed-sweep mode, a vertical line appearson the left edge of the screen, caused by the deflection ofthe beam in the absence of a horizontal trace.

Since this add-on unit can only be used on logic-levelsignals, the unit under test can supply power. No internalpower supply is shown, but you may prefer to add one.

The true amplitude of the signals on the SCOPE outputwill be less than the 2 V, 3 V, and 5 V levels in thedescription given here, because the output of the TTLdevices during their source mode are less than the supplyvoltage. Also, the resulting voltage will be furtherreduced by the input impedance of the scope.

Caution: If you're tempted to cut up the front panel of

September 1981 © BYTE Publications Inc 429

Technical Forum,

+ 5VA

GO O-

1K-WV-

2N2222

12K-VW-

8

,005/iF

C TSD

555CV OCG

GND Q

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50K

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IN914

2N2222

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• 10K

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TRIMMER

O.Ol^iF

8

TRIMMER10K-Wv

Vcc DCG

C TSG

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CV T

GND Q

1 3

. 0.05>iF

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LS7474bT Q

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■(I) A

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<wm?—.

•ruinju= ltltuIji

BRIGHT LINE

DRIGG

SCREEN(WITH DELAYED SWEEP)

,, , DELAY SCREEN

\X) PERIOD

(3a)

MUX= MULTIPLEXER

(3b)

(H) A

n_n_p b

Tnm?,7^

'luiruui

MUX E

RESISTORNETWORKMUX

Figure 3: Timing diagram for dual trace with delayed sweep.

your oscilloscope, remember that this unit will only ac-cept digital signals. Signals between about +0.8 V and+ 3 V fall in a "gray area" that may "confuse" digital cir-cuits. (A sinusoidal waveform, for example, would notbe displayed accurately.) Do not build in this unit if youwant to use your scope on operational amplification cir-cuits or power-supply ripple. ■

MUX=MULTIPLEXER

430 September 1981 © BYTE Publications Inc

DATA

(0 VOLTS)

IF CLK(0 VOLTS)

150K

f O

100K

SCOPE(0 VOLTS)

CHANNEL 2 LOW

DATA

(0 VOLTS

IF CLK(5 VOLTS)

150K

100K

SCOPE(3 VOLTS)

CHANNEL 1 LOW

(4a)

(4b)

CHANNEL 2 IN LOW ZONE

(4c)(4d)

CHANNEL 1 IN LOW ZONE

DATA

(5 VOLTS)

IF CLK(0 VOLTS)

150K

f O

100K

SCOPE

(2 VOLTS)CHANNEL 2 HIGH

DATA

(5 VOLTS)

IF CLK(5 VOLTS)

150K

CHANNEL 1 HIGH

^_c> SCOPE

(5 VOLTS)

CHANNEL 2 IN HIGH ZONE

CHANNEL 1 IN HIGH ZONE

Figure 4: Operation of the circuit shown in figures 1 and 2. Each of the four input conditions decodes to four different zones on theoscilloscope screen.

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System Notes

An Almost Optimum Z80Memory Test Program

Ira J Rampil, 60 Haven Ave Apt 15D, New York NY 10032

One of the great joys of building a computer is testingto see whether or not it works. The most interesting sub-system to check is the memory. Even average-sizedmemory systems contain several hundred thousand bits,each of which must be checked to insure that it can storeand output the desired data. The memory must also betested to confirm both the uniqueness of the address andthe absence of bit-to-bit interference. Problems such asprinted-circuit-board shorts and decoder-circuit bugs cancause data access at one address to disturb data at an en-tirely different address. Decoder-circuit bugs are usuallyencountered when a new memory is first brought up, butprinted-circuit-short problems can and do occur at anytime. Most memory component failures also occur early.

It is not feasible to detect and localize any but the mostsevere problems through the use of manual hardwaredebugging techniques. Memory bugs are best found byusing software techniques, provided that plugging thequestionable boards into the system bus doesn't cause thewhole system to crash. As long as the processor, someperipherals, and at least some memory are up, programscan be loaded and run to test the remaining memory.

The most obvious test is to store all possible combina-tions of bits. Unfortunately there are 2262144 possible com-binations in a 32 K- by 8-bit memory. To test each possi-ble combination separately would take a length of timesignificantly greater than the projected duration of theuniverse.

A great deal of research has been done in order to findtricks that will shorten the time required to test memory,but many manufacturers and suppliers of microcomputerkits seem unaware of the results. For example, I recentlybuilt a system kit that was supplied with a memory testprogram that counted from 0 to hexadecimal FF, check-ing each increment in every byte in memory. It took morethan five minutes per pass in my 34 K memory, and theprogram failed to detect four address-line foil bridges,one solder splash, and the bad decoder chip that mappedtwo 8 K boards into the same memory location. It didlocate a data-to-address foil short and a few bad memorychips, but the program crashed after every bug it caught.By contrast, the program I'm about to describe can detectall of these problems and most others, except certain bit-to-bit interference problems, within a single byte. It runs

on the same system in less than 3 seconds per pass.

Memory problems usually occur as input (address) oroutput (data) lines that are stuck at either a 0 or a 1, or aline having the value of a different line. Such problemsare the result of open circuits or shorts to power lines.Blown memory devices usually have bits that are inter-nally shorted or open. It should be understood thatmemory test programs will detect these problems andusually supply the offending addresses, but will almostnever diagnose the problem. Diagnosis remains a humanfunction that uses clues provided by memory test anddump routines. After localizing a bug, successive dumpsof the offending area of memory while changing data atthat address will reveal patterns characteristic of the par-ticular bug.

The program described here is based on an algorithmdescribed by John Knaizuk and C R P Hartmann (IEEETransactions on Computers, April 1977). This algorithmis called optimal because it uses the minimal number ofmemory accesses to test the memory for all single-bit er-rors. It also catches many multiple-bit errors.

The memory under test is divided into three partitionsbased upon the byte addresses modulo 3. When a parti-tion is accessed, all memory addresses within it are ac-cessed. Each partition is then independently accessed.The address lines and the decoding circuits are ex-haustively tested. Data lines and memory chips are alsotested, to the extent that each bit must be able to writeand read back both a 0 and a 1. The algorithm uses a totalof four accesses per address. This corresponds to thenumber of accesses required to read and write a 0 and a 1in each location.

The program shown in listing 1 was written for aDigital Group Z80 system, but it can be easily trans-ported to other Z80 and 8080 systems. The major changeswill be in the character output linkages and systemutilities. I do not claim that this code is optimally short orfast. It was written to be legible, and it is fast enough andreasonably short. If an error is encountered, the offend-ing address is printed, along with the erroneous data byteread and the correct byte. Errors do not terminate the testand an "A" is printed at the completion of the test se-quence. ■

432 September 1981 © BYTE Publications lnc

Listing 1: A memory test program for the Z80 microprocessor. Although written for a Digital Group Z80 system, it can easily bemodified for 8080 and other Z80 systems. Note the use of octal notation.

ASSM 006000 100000

006000

0100

006000

0110

006000

0120

006000

0130

006000

0140

006000

0150

006000

0160

006000

315

346

0000

0170

006003

0175

006003

0180

006003

0185

006003

315

251

006

0190

006006

0200

006006

0210

006006

0220

006006

021

001

000

0230

006011

315

117

006

0240

006014

021

002

000

0250

006017

315

117

006

0260

006022

021

000

377

0270

006025

315

117

006

0280

006030

021

001

000

0290

006033

315

147

006

0300

006036

021

001

377

0310

006041

315

117

006

0320

006044

021

002

000

0330

006047

315

147

006

0340

006052

021

000

377

0350

006055

315

147

006

0360

006060

021

001

377

0370

006063

315

147

006

0380

006066

021

000

000

0390

006071

315

117

006

0400

006074

315

147

006

0410

006077

021

002

377

0420

006102

315

117

006

0430

006105

315

147

006

0440

006110

076

201

0450

006112

315

372

000

0460

006115

030

264

0470

006117

0480

006117

0490

006117

0500

006117

052

255

006

0510

006122

173

0520

006123

205

0530

006124

157

0540

006125

174

0550

006126

316

000

0560

006130

147

0570

006131

162

0580

006132

043

0590

006133

043

0600

006134

043

0610

006135

170

0620

006136

274

0630

006137

330

0640

006140

040

367

0650

006142

171

0660

006143

275

0670

006144

330

0680

006145

030

362

0690

006147

0700

006147

0710

006147

0720

006147

052

255

006

0730

006152

173

0740

006153

205

0750

006154

157

0760

006155

174

0770

006156

316

000

0780

* AN ALMOST PERFECT MEMORY

* TESTER BASED ON THE K-H

* ALGORITHM. WRITTEN BY" IRA IAY RAMPIL FOR

* THE Z-80

**********************************

BEGIN CALL ERASE

* FIND TOP OF MEMORYMAIN CALL TOP

" TEST SEQUENCE

;CLEAR SCREEN

WR

WLP

RD

LD

DE, 000001

CALL

WR

LD

DE, 000002

CALL

WR

LD

DE,377000

CALL

WR

LD

DE, 000001

CALL

RD

LD

DE,377001

CALL

WR

LD

DE, 000002

CALL

RD

LD

DE,377000

CALL

RD

LD

DE,377001

CALL

RD

LD

DE,000000

CALL

WR

CALL

RD

LD

DE,377002

CALL

WR

CALL

RD

LD

A,301

CALL

TV

IR

MAIN

CUTIN

2 TO WRITE 1

LD

HL,(START)

LD

A,E

ADD

L

LD

L,A

LD

A,H

ADC

0

LD

H,A

LD

(HL),D

INC

HL

INC

HL

INC

HL

LD

A,B

CP

H

RET

C

JR

NZ.WLP

LD

A,C

CP

L

RET

C

JR

WLP

DUTIN

ETO READ A

LD

HL.(START)

LD

A,E

ADD

L

LD

L,A

LD

A,H

ADC

0

SIGNAL END OFTEST TO SCREENSTART OVER

SETUPSTARTINGADDR OFPARTITION

WRITE LOOPTO FILLPARTITION

Listing 1 continued on page 434

September 1981 © BYTE Publications Ire 433

System Notes.

Listing 1 continued:

006160

147

0790

006161

176

0800

006162

272

0810

006163

304

203

006

0820

006166

043

0830

006167

043

0840

006170

043

0850

006171

170

0860

006172

274

0870

006173

330

0880

006174

040

363

0890

006176

171

0900

006177

275

0910

006200

330

0920

006201

030

356

0930

006203

0940

006203

0950

006203

0960

006203

325

0970

006204

134

0980

006205

315

267

001

0990

006210

135

1000

006211

315

267

001

1010

006214

076

275

1020

006216

315

372

000

1030

006221

136

1040

006222

315

267

001

1050

006225

076

233

1060

006227

315

372

000

1070

006232

132

1080

006233

315

267

001

1090

006236

305

1100

006237

006

022

1110

006241

315

370

000

1120

006244

020

373

1130

006246

301

1140

006247

321

1150

006250

311

1160

006251

001

377

207

1170

006254

311

1180

006255

1190

006255

1200

006255

1210

006255

1220

006255

1230

006255

1240

006255

1250

006255

1260

006255

1270

006255

1280

006255

1290

006255

1300

006255

1310

006255

1320

006255

1330

006255

1340

006255

270

006

1350

RLP

ERR

SPACE

TOP

LD

H,A

LD

A,(HL)

CP

D

CALL

NZ.ERR

INC

HL

INC

HL

INC

HL

LD

A,B

CP

H

RET

C

JR

NZ.RLP

LD

A,C

CP

L

RET

C

JR

RLP

DUTIN1

I TO PRINT

PUSH

DE

LD

E,H

CALL

OCT

LD

E,L

CALL

OCT

LD

A, 275

CALL

TV

LD

E,(HL)

CALL

OCT

LD

A, 233

CALL

TV

LD

E,D

CALL

OCT

PUSH

BC

LD

B,22

CALL

TV-2

DJNZ

SPACE

POP

BC

POP

DE

RET

LD

BC, 207377

RET

;FOUND A BUG

;PUT OFFENDING ADDRESS ON TV

.-OUTPUT " = "

;OUTPUT OFFENDING CONTENTS ON TV

;OUTPUT DESIRED CONTENTS

;OUTPUT SPACES TO GET NEXT;LINE OF TV SCREEN

;MY SYSTEM'S TOP OF MEMORY

* TV IS A ROUTINE THAT OUTPUTS

* THE CONTENTS(CHARACTER) OF A

TV EQU 372

* OCT IS A ROUTINE THAT CONVERTS THE

* CONTENTS OF E FROM BINARY TO OCTAL

* AND THEN PRINTS IT ON TV

OCT

EQU 001267

* ERASE IS A ROUTINE THAT ERASES

* THE SCREEN

ERASE EQU 346START DW 006270

434 September 1981 © BYTE Publications Inc

Technical Forum

How to Build anInexpensive Cassette Level Indicator

Dr Milan D Chepko

119 Belleville Ct

Thief River Falls MN 56701

Looking for an inexpensive way to adjust the level ofyour recorder when loading programs into yourmicrocomputer? The circuit diagram in figure 1 showstwo LEDs (light-emitting diodes) and a 270- to 330-ohmresistor wired across the line from the recorder's ear-phone jack. The earphone or speaker is optional, but itallows you to hear the data transfer in operation. Aphotograph of the completed circuit is shown in photo 1.

Most microcomputers require about two volts of audiosignal for reliable operation. Since LEDs "turn on"at about 1.7 V, adjust the recorder's volume controluntil one of the LEDs begins to flicker steadily, and youshould be in business. The LEDs also seem to absorbsome of the extra signal if you turn the volume up toohigh.B

Technical Forum is a feature intended as an interactivedialog on the technology of personal computing. The subjectmatter is open-ended, and the intent is to foster discussion andcommunication among readers of BYTE. We ask that all cor-respondents supply their full names and addresses to be printedwith their commentaries. We also ask that correspondents supplytheir telephone numbers, which will not be printed.

Photo 1: The cassette level indicator built inside a small plasticbox.

output to [|v-

COMPUTER tl

MINIATURE

PHONE

JACK

' 330il

%

I

x-

SMALL

SPEAKER

OR EARPHONE

f TIL-209A

TYPICAL FOR 2

-B

TO EARPHONE JACK

J^ ON RECORDER

MINIATURE

PHONE

PLUG

Figure 1: Schematic diagram of the cassette level indicator.

September 1981 © BYTE Publications Ire 435

Software Review

Interactive Fiction:Six Micro Stories

Bob Liddil, The Programmer's Guild, POB 66, Peterborough NH 03458

Adventure International has a new concept in com-puter simulation called Interactive Fiction. The productI'm reviewing is a sampler of six Interactive Fictionstories. The sampler is, of course, designed to whet yourcuriosity about the full-length titles offered by the com-pany.

Defined in its simplest terms, an Interactive Fiction epi-sode is a story that needs your responses to achieve itsoutcome. It goes far beyond Adventure's two-word re-sponses by encouraging you to input complete sentences.I must confess that, at first, I was uncomfortable with thenew format. Gradually, though, I became accustomed tobantering with the computer.

The first story places you in wartime Nazi Germany.You're an Allied spy, and you must uncover as many se-crets as possible. You have been invited to a banquet,where you find yourself chatting with a high-rankingGestapo officer. The conversation between you and thecomputer determines whether you live or die.

In another scenario, you are a near-bankrupt shippingtycoon entertaining a Greek billionaire. He has just madea $30 million offer for your company, but you know thatin a day or so your company will be worth only $10 mil-lion. I took great delight in fleecing that fellow for $70million.

Interactive Fiction seems to be a stylized Eliza or DrChips, both of which are programs that cause the com-puter to act as if it understands your input. While givingthe illusion of intelligence, these scenarios actually have asmaller vocabulary than the most basic Adventures. Forexample, there's a story about a chance encounter in SanFrancisco. You're in a park and you stumble upon a pret-ty girl who has dropped her books. Her monosyllabicreplies not only break the mood of the story, but sadly at-test to the lack of intelligence in the program. Don't mis-understand me; these stories do have some redeemingqualities.

As in Eliza, the computer "psychiatrist," it is obviousthat the program zeros in on individual words, ignoring

most of the input. The rest of the stories in the samplerare similarly disappointing in their lack of versatility;there are only a couple of ways each story can be played.

I suspect that Six Micro Stories is not an adequateshowcase of the Interactive Fiction concept. The storiesfall far short of what the computer community expectsfrom Scott Adams. As a party mixer or novelty, this of-fering will fill the bill, but don't buy this package expect-ing the high-quality entertainment you've received fromAdventure International in the past.

Six Micro Stories should be approached as a sampler.If you expect more, you are inviting disappointment. Ifyou want to get into the heart of this new format, youhad better get Local Call for Death or Two Heads of theCoin, two full-length titles in the Interactive Fiction prod-uct line.B

Af a nianrp

Name

Language

Interactive Fiction: Six

Mixture of BASIC and

Micro Stories

machine code

Type

Computer

Adventure-type user-

Radio Shack TRS-80 Model

interactive game

I with one disk drive and

32 K bytes of memory

Manufacturer

Adventure

Documentation

International

Several screens of informa-

POB 3435

tion within the program

Longwood FL 32750

(305) 862-6917

Audience

Adventure enthusiasts and

Price

people who like role-playing

$15

games

Format

5-inch floppy disk

436 September 1981 © BYTE Publications Inc

SURE

THIIUG

HR5TER.

50 I FIND YOU NOT GUILTYUNDER THE CONDITION YOU\DE-BUG. THE ROBOT

"~~y~s-—^YOU GOT ITJUDG-EY VJUD&EYl

READ ME THAT NEW LISTINGIII BURN IT INTO THE NEW,iEPROM. ~

oooo D8 CLD

000/ Af 01 B/P LD/»*oiOOOJ SDOZ 19 STASI9020006 20 SI FE JMPi F£|lOO09 DO P4 BNE SIP

0O08 29

AND NOW THETEST...WHAT52+2?

HERECHILD5PLRV.JT5H.DDDnOl .

September 1981 © BYTE Publications Inc 437

INDIVIDUAL/NET

WORD PROCESSOR

S-100, 7 Slot, 360K Double Density

DUAL/NET

SMALL BUSINESSAPPLICATIONS

Up To 4 TerminalsCan Be Slaved Off Master

LOCAL/NET

TELEPHONE/NET

Configurability

SKTEM/NET

LARGE SYSTEM NUCLEUS

Hard Disc and 8" FloppyAny Combination of Master or Slave

MASTER/NET

"BUY" WORD FOR THE 1980's

NETWORKING is the newest 'buzzword' inmicroprocessors. Delta Products has produced asuperior hardware system that cannot be matched in.either cost or performance.

Don't buy a system that has "designed-in" limitations;check the following:

PERFORMANCE

This is where DP/NET® beats them all. Delta does multiuserand multitasking operations by using distributed processors.DIGITAL RESEARCH has provided a new operating system(CP/NET®) which combines MP/M® and CP/M 2.2® into theworld's most powerful microcomputer system.The system cannot be bogged down by adding more users.High-speed DMA transfers from Host to Slave, allow manyprocessors to share workloads. (There can be 3 processors atEACH user terminal; a ZSOfor screen function, and a pair of8085/8088 for main processing.)

FLEXIBILITY

One of the most important advantages of DP/NET® is thatyou never have to purchase more system than you currentlyneed. Your system can start with a 5" minifloppy 32Kterminal for under $3000.00. Adding a Second terminal andadditional mass storage is as simple as the originalpurchase. Networking up to 16 OR MORE intelligent andsemi-intelligent work stations can follow in perfect stepwith the growth of your Company and requirements.

COST

Since you never buy more computer power than you need, thesystem cost is matched to the demand to be placed upon it.DELTA PRODUCTS has a lot of experience in buildingmicros, with over 2000 DELTA systems now in the field.DELTA component cost has always been extremelycompetitive. DELTA'S new "networking system" is anatural and simple combination of the competitive "gooddeals" we have been offering for some time.

SOFTWARE

A computer system to the end user IS THE SOFTWARE. AllCP/M® compatible programs run perfectly on the DP/NET®.DELTA PRODUCTS is currently writing its' ownhigh-performance custom data base, screen editor, orderentry/inventory, and accounting packages in PL/1®. Targetrelease date for the complete package is November, 1981.

SOLD ONLY THROUGH DEALERSHIPSCALL FOR YOUR NEAREST REPRESENTATIVE

DELTA PRODUCTS

15392 Assembly Lane

Huntington Beach, CA 92649

TELEPHONE: (714) 898-1492

PRODUCTS

TELEX: 681-367 DELTMAR HTBH

MP/M, CP/M2.2, PL/1 & CP/NET ARE REG. TM OF DIGITAL RESEARCH INC.

Circle 395 on inquiry card.

AMAZING

VALUES.

FROM

(m)etatronics

^ ' CORPORATION

VISA

RETAIL STORE

22297EUCLID AVENUE

EUCLID, OHIO 44117

(EAST 222nd & EUCLID AVE.)

MOST ORDERS

SHIPPED WITHIN

ONE BUSINESS DAY

TRS-80 is a trademark of theRadio Shack Division of TandyCorporation. PLAIN JANE is aTrademark of Meta TechnologiesCorporation.

PRICES IN EFFECTSept. 1, 1981 THRUSeptember 30, 1981,

Prices, Specifications,

and Offerings subject to change

without notice.

• Add $3.00 for shipping & handling.•$3.00 EXTRA for C.O.D.

• Ohio residents add 51/2% salestax.

TO ORDER

CALL TOLL FREE

1-800-321-9390

IN OHIO, call

(216) 289-1210 (COLLECT)

OFFICES

26111 BRUSH AVENUE

EUCLID, OHIO 44132

(SEND MAIL ORDERS HERE)

1981 by Metatronics Corp.

440 BYTE September 1981

Circle 213 on inquiry card.

What's New?

SYSTEMS

The Stratos

The Stratos is a 4 MHz,Z80-based computer with 80 Kbytes of progammable memoryand 1.2 megabytes of floppy-diskstorage (expandable to 5 mega-bytes). Stratos features a ROM(read-only memory) monitor,CP/M 2.2, the Spellbinder word-processing program, a CBASIC ora Pascal compiler, business andpersonal-reminder software,printer driver routines for mostprinters, and two RS-232C ports.

Additional features of theStratos include a memory-mapped video controller, utilitiesthat allow many combinations ofdisk drives and formats to be con-nected, a light pen, and an AC-controller port. The Stratos micro-computer is housed in a teak-wood case. Contact SymbioticSystems Inc, 118 Naglee Ave,Santa Cruz CA 95060, (408)425-5533.

Circle 501 on inquiry card.

A Ralr Thing Indeed

Inside Rair Microcomputer Cor-poration's Black Box 3/30 is a5-megabyte Winchester hard diskand a dual-sided, double-densityfloppy-disk drive for backup. TheBlack Box 3/30 features either theCP/M or MP/M operating systemsand an IEEE-488 bus with 64 Kbytes of programmable memoryand 16 programmable I/O (in-put/output) ports.

For applications and develop-ment, Rair offers BASIC, PL/1,FORTRAN, COBOL, and Pascal.The Black Box 3/30 costs S7500.Contact Rair Microcomputer Cor-poration, 4101 Burton Dr, SantaClara CA 95050, (408) 988-1 790.Circle 502 on inquiry card.

Tiny BASICComputer Board

The K-8073 single-board com-puter features National's INS8073Tiny BASIC Microinterpretermicroprocessor. Features includeserial communication data ratesfrom 110 to 4800 bps (bits persecond), a cassette-tape I/O (in-put/output), 8 K bytes of EPROM(erasable programmable read-only memory), 1 K of program-mable memory with expansion to8 K externally, STD bus structure,remote controller for single-wiredata control from remote stations,and 24 bidirectional I/O lines. Theboard is supplied with a 2 K ROM(read-only memory) of develop-ment utilities and a real-timecalendar/clock.

The K-8073 requires + 5 V andcosts $388. Contact TranswaveCorporation, RD 1 Box 489, Van-derbilt PA 15486, (412)628-6303.

Circle 503 on inquiry card.

The LNW80Microcomputer

The LNW80 microcomputer issoftware-compatible with theTRS-80. It includes a 4 MHz,Z80A microprocessor, high-reso-lution black-and-white and colorgraphics, 12 K bytes of ROM(read-only memory), 16 K bytes ofprogrammable memory, upper-and lowercase display, reversevideo, an RF (radio frequency)modulator, expansion bus, cas-sette interface, and power supply.

The LNW80 costs $ 1664 witha black-and-white monitor and asingle 5-inch floppy-disk drive, butit can be purchased without peri-pherals for S 1200. For details,contact LNW Research Corpora-tion, 14661 C Myford Rd, TustinCA 92680, (714) 544-5744.Circle 504 on inquiry card.

Xerox820 Microcomputer

The Xerox 820 microcomputercan be used as a word-processingsystem, a business computer, orboth. The basic 820 system in-cludes two RS-232C and two par-allel ports, dual 5-inch floppy-diskdrives each with a 92 K-byte un-formatted capacity, a standardkeyboard, and a 12-inch black-and-white video-display monitorwith 24 lines by 80 characters.

The 820 features a -Z80 micro-processor with 64 K bytes of pro-grammable memory and 4 Kbytes of ROM (read-only mem-ory). The CP/M operating systemand applications software, in-cluding CBASIC-2, COBOL 80,MBASIC, and word-processingprograms, are available. A word-processing system utilizing Word-Star and the SuperCalc electronicspreadsheet are available as op-tions. It can be connected to theEthernet communications net-work. The Xerox 820 costs S2995and is available from Xerox andauthorized dealers. For further de-tails, contact the Office ProductsDivision, Xerox Corporation,1341 W Mockingbird Ln, DallasTX 75247.

Circle 505 on inquiry card.

Sierra 4000

The Sierra 4000 computer is anS-I00, Z80-based computer thatfeatures dual floppy-disk drivesand a hard disk. Together, thesedevices provide a total of up to 96megabytes of storage. A two-drive hard-disk system is optional.

For more information, contactSierra National Corporation, 5037Ruffner St, San Diego CA 9211 1,(714) 277-4810.Circle 506 on inquiry card.

September 1981 © BYTE Publications Inc 441

What's New?

SOFTWARE

MP/M-86Operating System

Digital Research's MP/M-86 is amultiuser operating system for8086-based microcomputers. It iscompatible with the CP/M-86operating system and programs.MP/M-86 will support networkingcapabilities through CP/NET. Itallows multiple users to executeprograms with only one copy ofthe object code in main memory.

Other features of the MP/M-86operating system are file andrecord lockout, standard in-put/output, and internal gueuemechanisms that support mutualexclusion, pipes, synchronizationand communication between

multiple tasks. Customizedoperating environments can bedefined within the MP/M-86structure. For more information,contact Digital Research Inc, POB579, 801 Lighthouse Ave, PacificGrove 93950, (405) 649-3896.

Circle 507 on inquiry card.

New PersonalSoftware Products

Personal Software has five newitems in its product line: a newversion of the VisiCalc businessand planning program and fournew VisiCalc-compatible pro-grams. The new VisiCalc pro-gram includes a full implementa-tion of a program-independentdata-storage format called DataInterchange Format. It allowstransfers of files between VisiCalcand other text and data programsregardless of format structure. AnEdit command lets users edit for-mulas without retyping them. Al-so Boolean functions and the abil-ity to choose specific elements ina list based on the results ofanother calculation are featured.The new VisiCalc costs S 199.95.

VisiPlot is a new VisiCalc-com-patible program with high-resolu-tion color plotting and graphics. Itcosts 5179.95. VisiDex is a per-sonal-information system thatcan handle mailing lists and per-sonal calendars. It costs S 199.95.VisiTrend/VisiPlot is a combina-tion of VisiPlot graphics and aprogram for time-series manipula-tion, trend forecasting, and des-criptive statistics. Its suggestedprice is S259.95. Then, there isVisiTerm, which can send and re-ceive files from the other Visi-programs over telephone lines toany other computer. VisiTerm is$149.95.

For details, contact PersonalSoftware Inc, 1330 Bordeaux Dr,Sunnyvale CA 94086, (408)745-7841.

Circle 508 on inquiry card.

Music Reader

Music Reader I shows you thenotes while it plays the melodythrough the Apple IJ's speaker.You can learn to read treble andbass clefs, note values, time andkey signatures, sharps and flats,

and complex rhythms becausethe program plays what youwrite. Music Reader I comes on afloppy disk and costs S30. Con-tact Shafer Software, 749 W Fre-mont Ave, Sunnyvale CA 94087.

Circle 509 on inquiry card.

Applesoft Compiler

The Hayden Book Company'sApplesoft compiler can increase aBASIC program's speed as muchas ten times and occupies only3.2 K bytes of memory. The17-pass compiler generates truemachine code. High-resolutiongraphics and shape tables aresupported, and multiple programscan reside in memory at the sametime.

Hayden's Applesoft compilerrequires a 48 K-byte Apple II Plusor Apple II with Applesoft in ROM(read-only memory), the Auto-start ROM, and at least onefloppy-disk drive. The compilercan be used with multiple- andhard-disk drives, and it can workon systems using the Apple Lan-guage Card or Microsoft RAM-Card. The compiler costs $200.Contact Hayden Book CompanyInc, 50 Essex St, Rochelle Park NJ07662, (201) 843-0550.Circle 510 on inquiry card.

Air Combat Game

The Computer Air Combatgame recreates World War IIaerial combat. The player(s)choose from thirty-six fighters orbombers. Each plane is rated inhistorical accuracy and detail forfirepower, speed, maneuverabili-ty, damage-tolerance, and climb-ing and diving ability. Five scenar-ios are provided to refight actualcombat engagements.

Computer Air Combat includesa rule book, two map-boardcharts, and three player-aidcharts. The game is available for48 K-byte Apple lis with Ap-plesoft in read-only memory anda floppy-disk drive. It costs$59.95. Contact Strategic Simula-tions Inc, 465 Fairchild Dr, Suite108, Mountain View CA 94043,(415) 964-1353.Circle 511 on inquiry card.

442 September 1981 © BYTE Publications Inc

What's New?

SOFTWARE

Language forEducation—Tl Logo

Tl Logo was designed for theTI-99/4 microcomputer. It is theend result of collaboration be-tween Texas Instruments and theMassachusetts Institute of Tech-nology. Tl Logo has been testedin schools in New York City andDallas, Texas, with students rang-ing from nursery school throughthe twelfth grade.

Tl Logo is structured so thatchildren can successfully use thecomputer with little formal in-struction. Students can draw geo-metric figures and designs andprogram the movement of specialgraphics figures. To work withthe language, students mustteach the computer what to do,which makes learning with TlLogo an interactive process ratherthan a feedback situation. UsingTl Logo, students make on-the-spot judgments as to whethertheir approach to a problem is ef-fective.

A Tl Logo set-up requires thesoftware and a TI-99/4 computerwith a video display, floppy-diskdrive and controller, and a mem-ory-expansion unit. Tl Logo soft-ware costs S299.95. For more in-

formation, contact the CustomerRelations Department, Texas In-struments Inc, POB 53, LubbockTX 79408.

Circle 512 on inquiry card.

The MDBS-QRS

The MDBS-QRS add-on letsnonprogrammers interrogate anyMicro Data Base Systems database using English-like com-mands. Utilities defining macroin-structions are included. Titles andsynonyms for the various data-base entities can be defined. Areport generated in response to aquery can be displayed in a stan-dard or customized format usingthe Report Writer feature. Stringcomparisons are allowed, and anoptional conditional clause canbe included for highly selectivedata retrieval. Existing data valuescan be modified. It is available forS300 from Micro Data Base Sys-tems Inc, POB 248, Lafayette IN47902, (317) 448-1616.

Circle 513 on inquiry card.

CP/M Cross-Assemblers

Avocet Systems's XASM familyof cross-assemblers can now runon 8080 and Z80-based micro-computers under CP/M and simi-lar operating systems. Pseudo-operation codes support nestedconditional assembly, listing-for-mat control, definition of mne-monic synonyms, and the inclu-sion of external source files. Theassemblers generate object files inthe Intel HEX format.

Other members of the XASMfamily of cross-assemblers are de-signed for 6805, 6801, 1802,6502, 6800, COP400, and othermicroprocessors. Each XASMcross-assembler costs S200; man-uals cost S25. Contact AvocetSystems Inc, 804 S State St, DoverDE 19901, (302) 734-01 51.Circle 514 on inquiry card.

Music andAnimation Program

Rainbow Writer is a graphics,text, music, and animation pro-gram that runs on the Apple \\and the Apple II Plus computers. Itcan create special effects thatfeature color, animation, letters,shapes, and sounds. The pro-gram lets users define characterfonts and choose between ninesizes and nineteen different colorsof upper- and lowercase Englishand Greek letters. Musically, theprogram offers six chromatic oc-taves and note sustain. Musicdata can be stored on disk.

The suggested retail price isS39.95. For details, contact Per-sonal Software Inc, 1330Bordeaux Dr, Sunnyvale CA94086, (408) 745-7841.

Circle 515 on inquiry card.

September 1981 © BYTE Publications Inc 443

What's New?

PUBLICATIONS

Evaluation ofEducational Programs

School MicroWare Reviews

contains user evaluations of in-structional programs and pack-ages for the Apple, PET, andTRS-80 microcomputers. Eachedition includes an index toevaluations in other publications.The reviews are organized byschool department and withinthat by subject. Each review con-tains comments about the qualityof the documentation, the in-structions to users given by theprograms, the student-computerdialogue, and other concerns.The evaluation includes the pro-ducer, price, hardware configura-tion, storage medium, programtype, grade level, and functionaldescription. School MicroWareReviews costs $30 per edition.

Also available is the SchoolMicroWare Directory. A sub-scription to it costs $20 per year. Itcontains descriptions of over 900programs. If you are a directorysubscriber and provide a course-ware evaluation that follows aform provided by the publishers,you can receive Reviews free ifyour evaluation is published.Nondirectory subscribers whosematerial is published receiveReviews at half price. ContactDresden Associates, POB 246,Department BY-1, Dresden ME04342, (207) 737-4466.Circle 516 on inquiry card.

Literature on ComputerScience and Technology

The United States GovernmentPrinting Office has books andmanuals on computer-relatedsubjects for sale. For informationon titles and ordering, contact theSuperintendent of Documents,US Government Printing Office,Washington DC 20402.

Circle 517 on inquiry card.

Microsoft Catalog

Microsoft Consumer Productshas a new catalog that describesall of the software products it pro-duces and sells. The free catalogis available at Microsoft dealers orby contacting the company at400 108th Ave, NE, Suite 200,Bellevue WA 98004, (206) 454-1315.Circle 518 on inquiry card.

StructuredRequirements Definition

Structured RequirementsDefinition, by Ken Orr, covers re-cent advances in systems theory,tools, and methodology. Thebook is written for analysts, pro-grammers, managers, and users.It is available for $25 from Ken Orrand Associates Inc, 715 E 8th,Topeka KS 66607, (800)255-2459; in Kansas (913)233-2349.

Circle 519 on inquiry card.

CoursewareEvaluation Guidelines

Guidelines for EvaluatingComputerized Instructional Ma-terials is a guide for buying andselling instructional software.Previous programming exper-ience is not assumed in this bookfor users and creators of edu-cational computer software. Divi-sions within the guide explainways to determine what sort ofsoftware is needed, how to lookfor it, and minor modificationsthat can be made.

Guidelines for EvaluatingComputerized Instructional Ma-terials costs $3.75. Contact theNational Council of Teachers ofMathematics, 1906 AssociationDr, Reston VA 22091, (703)620-9840.Circle 520 on inquiry card.

FORTH Beginner's Book

Starting FORTH is for noviceFORTH programmers. It em-braces such topics as definingwords, compiling words, vec-tored execution, virtual memory,and number-scaling techniques.Many programming examplesand illustrations are featured. Thebook is published by Prentice-HallInc. For more information, con-tact FORTH Inc, 2309 PacificCoast Hwy, Hermosa Beach CA90254, (213) 372-8493.

Circle 521 on inquiry card.

DEC LSI/PDP-11Systems Catalog

A catalog featuring DEC(Digital Equipment Corporation)LSI/PDP-11 computer systems,peripheral equipment, and soft-ware is available from Compu-mart Corporation. Compumartdistributes equipment and sys-tems from DEC and peripheralsfrom other major manufacturers.For your copy, contact Compu-mart Corporation, 65 Bent St,POB 568, Cambridge MA 02 139,(617) 491-2700.Circle 522 on inquiry card.

Software Protection

The legal protection of com-puter software is examined inComputers, Copyright and theLaw. This report was developedto help software authors makedecisions about protecting theirproduct's proprietary rights. Thereport encompasses the theoriesbehind software protection, but itemphasizes protection methodsand their relationship to softwaresales, leasing, and licensing. Con-tact Educational ProgrammingSystems, 1328 Baur Blvd, St LouisMO 63132, (314) 991-0300.

Circle 523 on inquiry card.

444 September 1981 © BYTE Publications Inc

What's New?

PUBLICATIONS

InternationalSoftware Directory

The International Microcom-puter Software Directory is a

reference source of new andestablished software for all ap-plications and systems. The direc-tory is divided into sections listingprograms for specific computers,describing categories of pro-grams, and a section for userswishing to buy from a particularsoftware house. Programs arecross-referenced throughout thesections. Details as to date ofrelease, warranties, distributors,medium, source code, compatiblesystems, special configurationsneeded, limitations, and prices areall provided.

The directory is availalble forS29; updates are available everysix months. System-specific direc-tories that are extracted andcross-referenced from the maindata base are available for SI2.These directories list programswritten for the Apple, TRS-80,and PET computers, and theCP/M operating system. Thedirectory is available from ImprintSoftware, 420 S Howes, Fort Col-lins CO 80521, (303) 482-5574.In England, contact Imprint Soft-ware, 16 Milton Ave, Highgate,London, N6.

Circle 524 on inquiry card.

600 MicroprocessorsCross-Referenced

The Microprocessor IC D.A.T.A.Book lists characteristics of over5000 integrated circuits, includingover 600 microprocessors andassociated programmable andread-only memory devices,interface-support circuits, pro-cessor architecture, and manufac-turer software support. Pro-cessors are cross-referenced bygeneric numbers, technicalcharacteristics, logic, block draw-ings, instruction sets, outlinedrawings, and manufacturers.The book is published twice ayear. The subscription rate is S55per year. Contact D.A.T.A. Inc.POB 26875-PR, San Diego CA92126, (800) 854-7030; inCalifornia (714) 578-7600.

Circle 525 on inquiry card.

Computer Music Journal

A special two-part issue ofComputer Music Journal, aquarterly from MIT Press, surveysthe applications of artificial in-telligence to music. Articles dealwith devices that will be capableof listening to, understanding andplaying music, and reports onresearch underway that hopes toexplain human musical cognition.Other topics include the use ofthe computer as an assistant formusical-score analysis and com-position, automatic musictranscription from sound to score,multilevel graphic representationof scores and sound in naturallanguages, intelligent music in-struments, new theories of music,and an introduction to LISP.

A subscription to the Com-puter Music Journal costs S25per year. Contact the MIT Press,28 Carleton St, Cambridge MA02142, (617) 253-2889.

Circle 526 on inquiry card.

Software-Vendor Directory

The fourth edition of the Soft-ware Vendor Directory contains1001 software vendors, 4195products, and 80 hardware and200 software categories. Thedirectory costs $57.95. Optional-ly, the directory can be purchasedfor S100, which includes two up-dates at six-month intervals. Asingle update costs $25. Also, aCP/M disk version is available for$78. Contact Micro-Serve Inc,250 Cedar Hill Ave, Nyack NY10960, (914) 358-1340.

Circle 527 on inquiry card.

Guide to PublishedMaterial on Computers

Bookguide 1: Microprocessorsand Microcomputers covers pub-lications that describe the con-cepts, applications, and potentialof microprocessor devices. It listsauthors, abstracts, publishers,and prices for nearly 500 titlesfrom 39 publishers. Books onmore than 50 topics ranging fromhistories to dictionaries,microcomputer architecture, pro-gramming techniques, personalcomputers, and artificial in-telligence, are listed. Bookguide 1is available for $11.50 fromLeatherleaf Book Services Inc,POB 28, Pembina ND 58271.

Circle 528 on inquiry card.

Books for the Apple

MICRO/Apple 1 is the firstvolume of a series of books thatwill contain articles from Micro,The 6502 Journal. The articlescontain Apple program listings,which are on a floppy disk thataccompanies the book.MICRO/Apple 1 costs $24.95, in-cluding the disk. Contact MicroInk Inc, POB 6502, ChelmsfordMA 01824.

Circle 529 on inquiry card.

September 1981 © BYTE Publications Inc 445

What's New?

PERIPHERALS

Connect an Olympla

ESIOOtoa

Microcomputer

Using the Ren Tec RS-232C in-terface, the Olympia ES100 type-writer can provide letter-qualityprinting and still function as astandard typewriter. The Ren TecRS-232C uses CMOS (comple-mentary metal-oxide semiconduc-tor) logic. It accepts an RS-232Cserial or a parallel interface; ac-commodates odd, even, or noparity; features handshake logic;and also provides any character-translation format.

The Ren Tec ES costs S295. Foradditional details, contact Ren-aissance Technology Corpora-tion, 3347 Vincent Rd, PleasantHill CA 94532, (415) 930-7707.

Circle 530 on inquiry card.

Color Printerfor the Apple

The OmniColor II is a color-inkjet printer with a 16 K- or 32 K-byte buffer. Intended for the Ap-ple II, software for 3.3 DOS is in-cluded. The OmniColor II useseight colors, prints at 40 cps(characters per second), and can

print paper up to 13 inches wide,as well as print overlay pages andscreens. It features normal or ex-panded print and the ability todot-plot any section of memory.Contact Omnico Computer Cor-poration, 3300 Buckeye Rd, At-lanta GA 30341, (404) 455-8460.Circle 532 on inquiry card.

Double YourGraphics Capability

The Double Hi-Res card pro-vides two levels of grey scale andcan display 80 columns by 24lines. It is designed for the Apple IIor III and is compatible with theApple Ill's super-high-resolutiongraphics. Character sets can bedefined with the Define Font pro-gram supplied. The Double Hi-Resfeatures italics, underline, multi-ple-character sets as well as

graphics on the same screen, pro-portional spacing, mathematicssymbols, and APL- and Japanese-character sets. Multiple-charactersets can reside in memorysimultaneously.

The price for the Double Hi-Rescard and support software on afloppy disk is $295. Contact SpiesLaboratories, POB 336, Lawn-dale CA 90260, (213) 644-0056.Circle 533 on inquiry card.

The Rhythm Box

The Rhythm Box synthesizesbass and snare drums, woodblocks, short and long cymbals,hand claps, and tom-toms. It isprogrammable in Level II BASIC orassembly language. The unit hasa phono jack for connection toan audio system, a power supply,a manual including BASIC and as-sembly-language software ex-amples, and a selection of rhythmcharts. The Model RBX-T for theTRS-80 Model I Level II is availablefor SI49.

The Model RBX-S is for S-100,Apple II, PET, and other systems.It connects to 9600 bps (bit persecond) serial interfaces usingeither RS232C or 20 mA current-loop levels. It costs $179. Formore information, contact New-tech Computer Systems Inc, 230Clinton St, Brooklyn NY 11201,(212) 625-6220.Circle 531 on inquiry card.

Thin Floppy-Disk Drives

The Thinline 8-inch floppy-diskdrives are 5.9 cm (23/,0 inches)high and weigh 7 pounds. Thesedouble-sided head drives can beturned on and off by control sig-nals from the interface. Headpositioning is accomplished by aband-driven carriage. The doorarrangement has been simplifiedby using a lever that closes andpositions the disk in the drive. TheThinline drives record at 48 and96 tracks per inch.

There are two models avail-able. The TM 848-1 stores 600 Kbytes on one side of a disk andTM 848-2 stores 1.2 megabyteson both sides. The drives can beused in single- and double-densityapplications. For more informa-tion, contact Tandon Corpora-tion, 20320 Prairie St, ChatsworthCA 9l3ll, (213) 993-6644.

Circle 543 on inquiry card.

11 by 11 Digitizer

The Demi-Pad is an 11- by1 1-inch digitizer tablet featuring a200-sample-per-second rate. It in-cludes a Z80-based interface,which provides RS-232C ASCII(American Standard Code for In-formation Interchange) or binary-coded data, and 0.001-inchresolution. The Demi-Pad comes

with a pen or stylus cursor.

Options include a power sup-ply, 16-button stylus or crosswirecursor, X Y display, and an ASCIIkeyboard. Priced at $990, theDemi-Pad is available from GTCOCorporation, 1055 First St, Rock-ville MD 20850, (301) 279-9550.Circle 534 on inquiry card.

446 September 1981 © BYTE Publications Inc

What's New?

MISCELLANEOUS

5-Inch Drives forthe TRS-80 Model III

Percom Data Company has5-inch floppy-disk drives for theTRS-80 Model III. Systems can beordered with either 40- or 80-track drives rated for double- andsingle-density operation. The firsttwo drives mount inside the com-puter; the others mount exter-nally. The first internal drivecomes with a four-drive con-troller, a two-drive power supply,cables, a double-density disk op-erating system, and mountinghardware.

The four-drive controller fea-tures data-separation and write-precompensation circuitry. It iscapable of handling two-headeddrives and single-density 8-inchdrives. The computer can use theModel Ill's disk operating systemor Percom's OS-80/III. The first in-ternal drive sells for S 749.95 inthe 40-track version and $914.95in the 80-track version.

The second internal drive in-

cludes the drive mechanism, elec-tronics, and installation hard-ware. It costs S315 in the 40-trackversion and $474.95 in the 80-track version.

Single external 40-track drivesare $439, and the dual 40-trackdrives are $878. Cables for the ex-

ternal drives are $29.95. For de-tails, contact Percom Data Com-pany Inc, 21 1 N Kirby, GarlandTX 75042, (800) 527-1592; inTexas, (214) 272-3421.

Circle 535 on inquiry card.

^5 ^

»!

Speech Processor

The Mimic speech processorconverts speech to digital dataand reconstructs the digital repre-sentation to analog form for re-production through a speaker.The system can be used for digitalspeech-communications applica-tions without a computer. Thespeech data rate is user-selec-table, with speech reproduced atrates from 9600 to 20,000 bps(bits per second).

There are four versions of the

Mimic speech processor: a S20bare board, an assembled andtested module for $79, a $149system configured for parallel-port interfacing, and a TRS-80-compatible plug-in version for$169. Documentation, includingprogram examples and schemat-ics for an S-l 00 bus interface, isalso available. Contact MimicElectronics Company, POB 921,Acton MA 01720.

Circle 536 on inquiry card.

Small-Systems Softwareand Services Sourcebook

Small Systems Software andServices Sourcebook lists andcross-indexes software and ser-vices available to users of mini-and microcomputers in business,

professions, and government. En-tries include software and servicelistings related to system soft-ware, application software, andconsulting and services in medi-cal, business, investment, model-ing, and other applications. The

book has some marketplace list-ings and display advertising. Formore information, contact Infor-mation Sources Inc, 1807 Glen-view Rd, Glenview IL 60025,(312) 724-9285.

Circle 537 on inquiry card.

September 1981 © BYTE Publications Inc 447

What's New?

MISCELLANEOUS

Buy and Sell

Horsetrader is a publication forbuyers and sellers of computerequipment. It features used, new,and rebuilt computers, terminals,printers, and other items. For in-formation on ad or subscriptionrates, contact Horsetrader, POBII712, Santa Ana CA 92711,(714) 832-0628.

Circle 538 on inquiry card.

Book Catalog

Telecom Library's 1981 catalogcontains more than 300 titles ofbooks, periodicals, trainingmanuals, and audio cassettes forinformation professionals. Thecatalog features books ontelecommunications manage-ment, data communications, dataprocessing, computer program-ming, office automation, wordprocessing, teleconferencing,satellites, and cable television.The catalog is free from TelecomLibrary Inc, 205 W 19th St, NewYork NY 1001 1, (212) 691-8215.Circle 539 on inquiry card.

CBASICProgram Directory

Compiler Systems Inc haspublished a directory listing 157business-application programs aswell as vertical-market packageswritten in CBASIC available from30 software vendors. TheCBASIC Software Directory pro-vides a description of each pro-gram, its memory requirements,and the vendor's name, address,and telephone number. Unlessnoted, all products support CP/Mand MP/M and require at leastone floppy-disk drive. The direc-tory is available for S 14.95 fromCompiler Systems Inc, 37 N Au-burn Ave, POB 145, Sierra MadreCA 91024, (213) 355-1063.

Circle 540 on inquiry card.

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Single-Board Computer

A single-board computer withanalog, serial, and power-controlI/O (input/output) has been an-nounced by Wintek. The boardfeatures a 6801 or 68701 micro-processor with 2 K bytes of ROM(read-only memory), 128 bytes ofprogrammable memory, and aninternal and an external timer.The 12-bit A/D (analog-to-digital)converter can be configured foreight single-ended or four dif-ferential inputs. The eight digitalI/O lines can be configured for

any mix of AC or DC inputs oroutputs. The serial I/O allowshalf-duplex 20 mA current-loopcommunication to a host com-puter at software-selectable rates.The prices range from S88 toS295, depending on options andquantity. Applications include re-mote data acquisition, machinerycontrol, and energy manage-ment. Contact Wintek Corpora-tion, 1801 South St, Lafayette IN47904, (317) 742-8428.

Circle 541 on inquiry card.

Software for the Atari

Personal Software has intro-duced MicroChess and CheckerKing for the Atari 400 and 800microcomputers. Both games fea-ture an on-screen, real-time clockfor game timing. The games re-quire 8 K bytes of memory andare priced at S19.95 each, on cas-sette.

The MicroChess program turnsa color-display screen into achessboard. It has eight selectable

levels of play, plays by tourna-ment rules, and allows no illegalmoves.

Checker King allows single,double, and triple jumps, forcesjumps, and performs according tothe tournament rules of checkers.For details, contact Personal Soft-ware Inc, 1330 Bordeaux Dr, Sun-nyvale CA 94086, (408) 745-7841.

Circle 542 on inquiry card.

448 September 1981 © BYTE Publications Inc

AD & DA CONVERTER

Z80 MICROCOMPUTER

6522 APPLE II INTERFACE

JBE one channel A-D & D-A Convertercan be used with any system havingparallel ports • Interfaces with JBEParallel I/O Card • D-A conversiontime — 5 /js • A-D conversion time —20 >js • Uses JBE 5V power supply

• Parallel inputs & outputs include 8data bits, strobe lines & latches

• Analog inputs & outputs are mediumimpedance 0 to 5 volt range. ^

79-287

Bare Board $39.95

ASSM, $78.95

Kit $59.95

6502 MICROCOMPUTER

JBE's 41/2x31/< dedicated controllerfeatures: • 1024 bytes RAM (two 2114s)• 2048 bytes EPROM (2716) • Uses one6522 VIA (comp. doc. incl.) • Interfaceswith JBE Solid State Switches & A-D &D-A Converter • Uses JBE 5V powersupply •2716 EPROM availableseparately (2716 can be programmedwith an Apple II & JBE EPROM Pro-grammer & Parallel Interface) • 50 pinconnector included In kit & assm.80-153 ASSM. $110.95

Bare Board $49.95 Kit$ 89.95

SOLID STATE SWITCH

'Jfc —^•♦flfl-

«srsll Hr^fl '^^ffl *srsf?'

Your computer can control power toyour printer, lights, stereo & any120VAC appliances up to 720 watts (6

amps at 120VAC). Input 3 to 15VDC• 2-14MA TTL compatible • Isolation— 1500V • Non zero crossing • Comesin 1 or 4 channel version.

79-282-1

Bare Board $6.95

79-282-4

Bare Board $24.95

ASSM. $13.95Kit $10.95

ASSM. $49.95Kit $39.95

APPLE II DISPLAY BOARD

JBE's 4-1/8"x3-1/4" single boarddedicated computer is designed forcontrol functions. It features: • A Z80Microprocessor software compatiblewith the 280, 8060 & 8085Microprocessors • Uses a Z80 PIO chipfor I/O which has 2 independent 8 bitbidirectional peripheral interface portswith handshake & data transfer control• Uses one 2716 EPROM (2K) & two 2114RAM memories (1K) • Single 5V powerSupply at 300MA req. • Clock frequencyis 2MHz, RC controlled • Board comeswith complete doc. • 50 pin connector isincluded *2716 EPROM availableseparately.

80-280 ASSM. $129.95

Bare Board $49.95 Kit $119.95

PRINTER INTERFACE

JBE Parallel Printer Interface interfaces yourApple II® to Centronics" compatibleprinters. This 3" x 4" board features: on boardROM compatible with Integer Basic,Applesoft* and Pascal* • Has one 8 bitparallel latched output port with selectablepositive or negative strobe and one bit inputselectable for Ready or Reedy • Cable andConnectors available separately.

80-297 ASSM. $79.95

Kit $69.954 ft. Std. Dip Jumpers 16 pin $4.25

Champ Connector $ 9.95

POWER SUPPLIES

• Use wall transformers for safety

• Protected against short circuit andthermal breakdown.

5 VOLT POWER SUPPLY

Rated at 5V 500MA • Operates JBE A-D& D-A Converter, Z80 & 6502 Microcom-puters, 8085 & 8088 Microcomputers.80-160 ASSM. $20.95

Bare Board $8.95 Kit $16.95

± 12 VOLT POWER SUPPLYRated at ± 12V120MA • Can be used asa single 24V power supply • Ideallysuited to OP-AMP experiments.80-161 ASSM. $22.95

Bare Board $8.95 Kit $18.95

80-144

Bare Board $25.95

ASSM. $49.95Kit $42.95

• Has run-stop, singlestep switch • Has 16address LEDs, 8 dataLEDs & 1 RDY LED

• All lines are buf-fered.

ICS

6502 $9.95

6522 $9.95

Z80CPU $9.95Z80 PIO $9.952716 $14.952716 Programmed

• Interfaces printers, synthesizers,keyboards, JBE A-D & D-A Converter &Solid State Switches • Has handshak-ing logic, two 6522 VIAs & a 74LS05 fortiming • Inputs & outputs are TTLcompatible.

79-295 ASSM. $69.95

Bare Board $39.95 Kit $59.95

2716 EPROM PROGRAMMER

JBE 2716 EPROM Pro-grammer was designedto program 5V 2716EPROMS • It can alsoread 2716s. It interfacesto the Apple II usingJBE Parallel I/O Card &four ribbon cable con-nectors • An LED indicates whenpower is being applied to the EPROM• A textool zero insertion force socketis used for the EPROM • Comes withcomplete doc. for writing and readingin the Apple II or Apple II + • Cablesavailable separately.80-244 ASSM. $49.95

Bare Board $24.95 Kit $39.95

2 Ft. Ribbon Cable $ 4.25

BARE BOARDS

APPLE II EXTENDER BOARDSW'xZVt". Price Includes 50 pin Con-nector.

80-143 $12.95

8085 3 CHIP SYSTEM

State-of-the-art system using an 8085,8156 & either an 8355 or 8755

• Instruction set 100% upward com-patible with 8080A.

Bare Board $24.95

8088 5 CHIP SYSTEM

An 8086 family microcomputer systemusing an 8088 CPU, 8284,8155,8755A& an 8185.Bare Board $29.95

CRT CONTROLLER

This intelligent CRT Controller usesan 8085A CPU & an 8275 IntegratedCRT Controller. It features: • 25 lines(80 Char./line) • 5x7 dot matrix • Upper& lower case • two 2716s (controller &char, generator) • serial interfaceRS232 & TTL • baud rates of 110,150,300, 600, 1200, 2400, 4800 & 9600

• keyboard scanning system • unen-coded keyboard is req'd • uses + 5V &± 12V power supplies • Doc. includesprogram listing & composite video cir-cuit.

$39.95$19.95

Bare Board only (Doc. incl.)Programmed 2716s each

$19.95

all products are available from john bell engineering • p.o. box 338redwood city, ca 94064 • add sales tax in california • add 5% shipping & handling

(415)367-1137 10% outside u.s.a.

VISA

Circle 38 on inquiry card.

BYTE September 1981 449

What's New?

MISCELLANEOUS

Compact FluorescentDisplay Panel

The itron square-formatDM128X128C 128 by 128 dotmatrix display panel is slightlyover 76.6 by 76.55 mm square (3inches) and only 20 mm (0.8inch) thick. It is capable of display-ing special symbols, geometricpatterns, graphics, block and cur-sive alphanumerics, continuously

scrolling images, and lightedareas. Each dot is individually ad-dressable, and ascenders and de-scenders, script lettering, lineargraphics, and charts can be pro-duced. For more information,contact Noritake Electronics Inc.22410 Hawthorne Blvd, TorranceCA 90505, (213) 373-6704.

Circle 544 on inquiry card.

Where Do New Products Items Come From?

The information printed in the new products pages of BYTE is obtained from"new product" or "press release" copy sent by the promoters of new products. Ifin our judgment the information might be of interest to the personal computing ex-perimenters and homebrewers who read BYTE, we print it in some form. Weopenly solicit releases and photos from manufacturers and suppliers to thismarketplace. The information is printed more or less as a first-in first-out queue,subject to occasional priority modifications. While we would not knowingly printuntrue or inaccurate data, or data from unreliable companies, our capacity toevaluate the products and companies appearing in the "What's New?" feature isnecessarily limited. We therefore cannot be responsible for product quality orcompany performance.

PiggybackedPrototyping Boards

Circbords are perforated proto-typing boards that can add 24square inches of working areaand 20 to 60 DIP (dual-inlinepackage) positions whenmounted on spacers, piggyback-style, on edge connector boards.Circbords can also be installed us-ing card guides or in aluminumextrusions.

The Model 8001 is designed forsolder connections. It holds up totwenty 16-pin integrated circuits.The Model 8002, for wrappedwire, can hold up to thirty-five16-pin DIPs. On the 8003 model,up to sixty 16-pin DIPs, or anycombination of devices, can beattached using solder or wire-wrap. Each Circbord costs S9.95.Contact Vector Electronic Com-pany, 12460 Gladstone Ave, Syl-mar CA 91342, (213) 365-9661.

Circle 545 on inquiry card.

16 K-ByteROM from OKI

OKI Semiconductor Inc has in-troduced an NMOS (n-type metal-oxide semiconductor), 128 K-bitROM (read-only memory). TheMSM-38128 is organized as 16 Kbytes by 8 bits. It has a 450 nsmaximum access time, operatesoff a single + 5 V supply, andfeatures a 120 mA supply cur-rent in the operating mode and20 mA current in standby. Com-patible with the 128 K-bit 2364ROM from Intel, the MSM 381 28features power-down state and isnonclocked. All inputs and out-puts are TTL (transistor-transistorlogic) compatible.

For information, contact thethe company at 1333 LawrenceExpy, Suite 401, Santa Clara CA95051, (408) 984-4842.Circle 546 on inquiry card.

450 September 1981 © BYTE Publications Inc

THE STAR MODEM

From Livermore Data Systems

RS232 MODEMIEEE 488 MODEM

RS232 CCITTIEEE 488 CCITT

SALE $128SALE $199

$170$280

STAR Modem is the price performance leader with a t2 YEAR FACTORY WARRANTY.

We carry Apple 11+ fromBell & Howell

PROGRAM YOUR OWN EPHOMS

Bunding Iron for PET/CBM $79

EPROM Projnmnur with software for all ROM ver-sions. Includes ill necessary hardwire and software toprogram or copy 2716 and 2532 EPROMS.

Paper-Mate Word Processor $39.95

PET/CBM full featured 60 command system by MichaelRiley. Uses either tape or disk and any printer. Includes in-text commands, tloating cursor, scrolling, etc.

FlexhfTlTiMi Base for CBM/PET $60

Random file handling system with Report Writer and MailLabel Handler. By Michael Riley.

REVERSAL (Spracklen) 32K Apple 28.00

Super FORTH 48K Apple 40.00

Energy Miser for PET, Apple, or Zenith 24.50

Data Manager (Lutus) 24K Apple 40.00

Histo-Graph (Boyd) 48K Apple 24.50

Data-Graph (Boyd) 48K Apple 40.00

Apple II User's Guide (Osborne) 12.00

Introduction to Pascal (Sybex) 10.30

Pascal Handbook (Sybex) 12.00

Graphics Cookbook for Apple 9.90

Musical Applications of Micros (Chamberlin) 20.00

Basic FORTRAN (Coan) 7.25

KM MM Pascal for PET $75

Subset ol standard Pascal with true machine languagetranslator for faster execution. 16K with tape or disk.

EARL for PET (disk file based) $65

Editor, Assembler, Relocator, Linker to generate relocat-able object code.

FORTH for PET/CBM or Apple $65

A full-featured FORTH with extensions conforming to ForthInterest Group standards. Includes assembler, string pro-cessing capabilities, disk virtual memory multiple dimen-sioned arrays, floating point and integer processing.

MIPLOT Intelligent Plotterby Watanabe Instruments (Digiplot)

SPECIAL$1195

Has all intelligent functions for producing graphs anddrawings including i vector and 4 character commandsSolid and broken lines can be specified. Character gen-erator for alpha, numeric, and symbols. Characters can berotated in 4 orientations, and can be 16 sizes. Coordinateaxes drawn by specifying graduation interval and numberof repetitions Parallel ASCII interface, 11x17 paper.

SPECIALS

EPSON MX-80 Printer

475

EPSON MX-80 F/T Printer

575

EPSON MX-70 Printer

380

EPSON MX-100 Printer

770

Centronics 739 Printer

750

STARWRITER Daisy Wheel Printer

1445

Leedex Video 100 12" Monitor

129

ZENITH DATA SYSTEMS

Z19 Video Terminal

729

Z89 with 48K

2150

Extra 16K RAM

115

Z-47 Dual 8" Drive

2775

SYM-1 209

SYM BAS-1 BASIC or RAE-1/2 Assembler 85

KTM-2/80 Synertek Video Board 349

65026502A6520 PIA6522 VIA6532

7.458.405.156.457.90

2114-L200 ns RAM2114-L300 ns RAM2716 EPROM2532 EPROM4116 200nsS-100 Wire WrapZero Insertion Force 24

10/6.95 50/6.55 100/6.15

10/7.95 50/7.35 100/6.90

10/4.90 50/4.45 100/4.15

10/6.10 50/5.75 100/5.45

10/7.40 50/7.00 100/6.60

3.75 25/3.50 100/3.25

3.15 25/2.90 100/2.65

7.75 5/7.45 10/6.90

17.00

8 lor $20

2.65

pin Socket $2.00

««

CASSETTES - AGFA PE-611 PREMIUM

High output, low noise, 5 screw housing, labels.C-10 10/5.65 50/25.00 100/48.00

C-30 10/7.30 50/34.00 100/66.00

All other lengths available. Write for price list.

commodore

CBM-PET SPECIALS

o Up to $375 tree merchandise I£V *lth purchase of one olfollowing CBM-PET Items:

8032 32K - 80 Column CRT8050 Dual Disk Drive4016 Full Size Graphics Keyboard4032 Full Size Graphics Keyboard8096 96K - 80 Column CRT2040/4040 Dual Disk Drive - 340K4022 Tractor Feed PrinterCBM Voice SynthesizerC2N External Cassette DeckUsed CBM/PET ComputersVIC Personal Computer

WRITE FOR SYSTEM PRICES

DISKSPECIALS

SCOTCH (3M) 5W 10/2.85 50/2.75 100/2.65SCOTCH (3M) 8" 10/2.90 50/2.80 100/2.70

Verbatim 5V 10/2.45 50/2.40 100/2.35

(add 1.00 for 5W' Verbatim plastic storage box)Verbatim8"Dbl.Dens. 10/3.45 50/3.35 100/3.25BASF 5'A" 10/2.40 20/2.35 100/2.30

WRITE for prices on WABASH DisksWE STOCK MAXELL DISKS

1295 260

795 140

395 50

95 12

CALL

300 25

Diskette Storage PagesDisk Library Cases

8" - 2.85

10 for 3.955"-2.15

A

ATARI 800 $745

All Atari Modules 20% OFF

*** EDUCATIONAL DISCOUNTS ***Buy 2 PET/CBM Computers, receive 1 FREE

WordPro 3+ - 32K CBM, disk, printer 250

WordPro 4+ - 8032, disk, printer 335

OZZ Data Base System for CBM 8032 335

VISICALC for PET or ATARI 170

SM-KIT - Super PET ROM Utllltites 40

ATARI EDUCATIONAL PLAN

—r

A P Products 15% OFFA P Hobby-Blox 15% OFF

Write fer details.

4 PART HARMONY MUSIC SYSTEM for PET

The Visible Music Monitor, by Frank Levinson, allows youto easily enter, display, edit and play 4 part harmonymusic. Includes whole notes thru 64ths(with dotted andtriplets), tempo change, key signature, transpose, etc. TheKL-4M unit includes D to A converter and amplifier (addyour own speaker).KL-4M Music Beard with VMM Pniorsm S59.90

Programmers Toolkit - PET ROM Utilities 34.90

PET Spacemaker II ROM Switch 36.00

2 Meter PET to IEEE or IEEE to IEEE Cable 40.00

Dust Cover for PET 6.90

IEEE-Parallel Printer Interface for PET 110.00

IEEE-RS232 Printer Interface for PET 120.00

The PET Revealed 17.00

Library of PET Subroutines 17.00

Source Hookup over 1000 programs/services

The 8086 Book (Osborne)Z8000 Assembly Language ProgrammingPET Personal Computer Guide (Osborne)PET and the IEEE-488 Bus (Osborne)6502 Assembly Language (Osborne)Programming the 6502 (Zaks)6502 Applications Book (Zaks)6502 Software Cookbook (Scelbi)CP/M Handbook (w/ MP/M) ZaksPractical BASIC Programs (Osborne)Some Common BASIC Programs (Osborne)

252 Bethlehem PikeColmar, PA 18915

215-822-7727

A B Computers

88

WRITE FOR CATALOG.

AddSt 25 per order for shipping We pay balance of UPS surface chargeson all prepaid orders Prices listed are on cash discount basis Regularprices slightly higher

Circle 4 on inquiry card.

BYTE September 1981 451

™'™HeathUsers

Double Your5V," disk storagecapacity without adding a drive.

Get twice as much from your H88 orH89 microcomputer. Our FDC-880Hfloppy disk controller, in conjunctionwith your 5V," drives, for example,expands memory capacity from 256bytes to 512 bytes per sector.

And it handles single and double-sided, single and double-density, 8" and51/," drives — simultaneously.

Call 714/275-1272 todayor write for details.

m

C.D.R. Systems Inc.

Controlled Data Recording Systems. Inc.7667 Vickers St., San Diego, CA 92111

ONE BOARD CP/M SYSTEM!

only $750

Assm., Tested

& Burned-In

for one week

Features:

• 8'/s by 12 inches

• 10 MHZ 8085 CPU

• 64K RAM

■ 3 RS-232 channels

• 8272 Floppy Disk Controller

• Handles Single/Double Density

• One to Four Drives. 801R or850R.

Documentation S15.

CP/M Floppy Disk Operating System S150

Check or Money Order

(autocontroll ^*\11744 Westline Industrial Drive 1

St. Louis. MO 63141 1

(314)432-1313 ^J

AC-85CP/M® SYSTEM

Assm., Tested& Burned Infor one week

$2450

Features:

• One board 8085 Computer

• 2 - SA800R* (1.2 megabytes)

• CBIOS Diskette

• Installed and wired in a cabinet withP/S and Fan ready to plug-in

• Manual

• 17'/i" Wx 17" Dl 10" H

» SYSTEM with 2 SA850R (2.4 mbytes)

$2750.00

CP/M Floppy Disk Operating System $150Check or Money Order

autocontroll

11744 Westline Industrial Drive

St. Louis, MO 63141

(314) 432-1313

® CP/M is a registered trademark of Digital Research, Inc.

Circle 55 on inquiry card.

Circle 32 on inquiry card.

Circle 33 on inquiry card.

Scotch*

DISKETTES

SAVE 40% XS&SSZ5%"Sgl. Dens. 26.70/10

Specify soft, 10 or 16 hard sectors

8"Sgl. Dens. 27.30/108"Dbl. Dens. 35.80/10

Specify soft or 32 hole hard

Add $2.00 shipping - Michigan add 4% tax

LYBEN COMPUTER SYSTEMS

27204 Harper Ave.

St. Clair Shores, Ml 48081

Authorized DistributorInformation Processing Products

ATARI OWNERS

Parallel Printer Interfacefor the ATARI 800

connects 1o controller jacks 3 and 4works with BASIC/DOS/ASSEMBLER

FOUR printer connectors available:

TRENDOCM 100/200 A8P-1

ATARI 825/CENTRONICS 730/737 . . A8P-2

EPSON MX-80/MX-70 6 other 36 pin- A8P-3

'Fits all other parallel Centronics plus

Okidata, Anadex, Base 2 Microtek, etc.

I.D.S. PAPER TIGER 440/445 ... A8P-4

$69.95

CA sales tax

order by pari number M.C./VISA accepted

GRAPHICS PRINTING SOFT WARE &ATARI 400 printer interlaces also available

©

To order toll free 1 800-344-7493In CA call 12091 667-2888

/VL4CROTRONICS, inc.. {Qfi

WANTED:

APPLE, PET, TRS-80, CP/M

SOFTWARE

Westico is a publisher and distributor ofprofessional software for microcomputers.If you have a new program ready fordistribution or want your existing programsto reach a larger market, contact

Phillip Woellhof, V.P. Mktg.

Westico, Inc.

25 Van Zant Street

Norwalk, CT 06855

(203) 853-6880To increase your profits, take advantageof Westico's worldwide promotion anddistribution.

WESTICO

The Software Express Service

Circle 196 on Inquiry card.

Circle 197 on inquiry card.

CONTROLS

SINGLE BOARD Z-80A* COMPUTER FOR CONTROL USES

ai Test EquipmentIntelligent Ponpno.ai Comr

Solar Healing & Power Sy:

Appliance Control

FEATURES: J MHZ Z-80A- ion DoatO ctystal,. Ik HAM, sockois tot 2 2N6's (4KPROM I. 3-B O.I parallel TTL output pons. 2-fl tut parallel TTL input potts. 8 analog inputpom (100 (isec conversion lime), 6 nigh cutienl output linos (open collector). 4 opto-isolated input f.nes. e*»a sing.'o nil TTL oulput lot senal IfO, 2-80 coniiol lines Dioughl toodgo connector, eitra port decodes brought to edge connector. I input port doubles asbuslorporlo<pansion.onboaid5viequlaioi.4ViiaPCboai0.uiUbslnrdaid72pinodgoconnector, fully socketed, requites rBla ID volts, 500 mA

PRICE: s;95

or PROM :W6Fu*l

or pirjyr.im with download

COMPUTER-AID

1122 DE LA VINA SANTA BARBARA, CA 93101 (8015)966-3077

TM

CP/M COMMUNICATIONS

LYNC

THE BEST AVAILABLE PROGRAM

FOR CP/M COMMUNICATIONS

LYNC is extremely powerful and easy lo use and a must (or even/ computeruser (hat wants to communicant with time-sharing systems or other CP/Mcomputers.

TERMINAL MODE

In this mode your system acts as a terminal. Can send lo Ot receive from atimesharing system When roceiving data Irom a remote system, receiveddata is buttered to your maximum memory, then can be saved as a disk tile

LYNC MODE

Communicate on-linB with another computer similarly equipped Both endscan type messages thai appear simultaneously on both screens

SEND: AUTOMATIC ERROR DETECTION A RETRY

LYNC sands block ol information with 16 bit checksums In case of error it willkeep retrying until successful

FETCH

Once botn systems are in LYNC mode, either operator can FETCH tiles fromother system

REMOTE AND LOCAL DIRECTORY

Can display both local and remote directories

BAUD RATES: UP TO 9600 BAUD

SELF GENERATING I/O ROUTINES REQUIRE NO

PATCHING

PRICE: S95 TERMS MONEY ORDER. CHECK, COD, M.C. OR VISAPLEASE SPECIFY DESIRED FORMAT: 6" Single Density; 5" Micropolis;TRS-80 Mod II wilh CP/M. North Star single or double density: Superbrain3.0 DOS or later, Cromonco 5" single density.

COMPUTER-AID

1122 DE LA VINA • SANTA BARBARA, CA 93101 (805) 966-3077

Circle 71 on inquiry card.

Circle 72 on inquiry card.

Circle 386 on inquiry card.

NOBODY KNOWS MORE ABOUT

ADDING MEGABYTES TO YOUR

TRS-80 MODEL II* THAN

AMERICAN SMALL BUSINESS

COMPUTERS

THE CAMEO CONNECTION

The Cameo 10 Million Cha-racter Disk Drive Subsystem(pictured in foreground) Is A5 Megabyte Fixed, 5 Mega-byte Removable Cartridge-Type Disk Drive. Advan-tages To This Unit Are Easeof Backup For Data and Pro-gram Filesand Low Cost. ByAttaching A Multiplexor UnitSeveral Model ll's Can BeAttached To The Cameo DiskDrive. For Further Pricing,Availability, and OperatingSystems Options, Call orWrite to American SmallBusiness Computers and askfor the CAMEO CONNEC-TION.

THECORVUSCONNECTION

The Corvus Disk Drive Sub-system (center of picture) IsAvailable in 5, 10, and 20Million Character Capacities.The Corvus System Is TheUltimate In The Sealed"Winchester, All-Fixed"Type Drive. The Corvus IsDesigned To Operate In TheHarshest Environments SuchAs Factories, Oil Rigs, Etc.Backup Of Data Is Accom-plished Via Optional MIR-ROR Backup Device Where-by Data Is Written Onto AStandard Video Tape Record-er. A Great Number ofModel ll's May Be AttachedTo The Corvus Via .AnOptional CONSTELLATIONMultiplexor. For FurtherPricing, Availability, andOperating Systems, Call OrWrite to American SmallBusiness Computers and Askfor the CORVUS CONNEC-TION.

THE AMERICAN SMALL BUSINESS COMPUTERS MINI-WINCHESTER SPECIAL

The M IN 1-5 (being held by Corporate President Robert Webster) Is American Small Business Computer's Very OwnDisk Subsystem. The MINI 5 Offers Approximately 5 Million Characters of Information Storage and is Based On theFamous Seagale Technology ST-506 Micro Winchester Drive. Now You Can Own State-Of-The-Art Technology At AnAffordable Price - Only $3500 - Which Includes Drive, Controller Electronics, Power Supply, Cabinet, Cables, Docu-mentation and Operating System Software.

DEALER INQUIRIES INVITED

Circle 17 on inquiry card.

AMERICAN SMALL BUSINESS COMPUTERS

•TMTANDYCORPORATION

118 SOUTH MILL STREET PRYOR, OK. 74561 918-825-4844

NEW! forthe '89 from

MAGNOLIAS

MICROSYSTEMS

DOUBLE DENSITYDISK CONTROLLER

for both 5V4"Sl 8" drives

only ibOvdO complete

including CP/M™2.2

MAGNOLIA MICROSYSTEMS. INC.

2812 Thorndyke W., Seattle 98199

1206) 285-72BB C800) 426-2841

CP/M is a trademark of Digital Research,

COMPUTER SHOWS

SECOND ANNUAL

NJ MICROCOMPUTER

SHOW AND FLEAMARKET- 1981

NEWARK, NEW JERSEY

Sat. Oct. 24 n Sun. Oct. 25

10-5:30 PM « 10-3:00 PM

HOLIDAY INN (NORTH)

NJ Turnpike t Exit 14

(Take Route 1-9 Service Road - Follow Signs)

REGISTRATION $5.00-

FLEAMARKET ONLY $3.00

Fleamarket Permits $5/Spot

(Includes Admission)

Commercial Exhibits •User Groups* Fleamarket

SECOND ANNUAL

NATIONAL"80" MICROCOMPUTER

SHOW (FOR TRS-80* USERS)

April 29, 30, May 1, 1982

NEW YORK STATLER HOTEL

NEW YORK CITY

100 Exhibit Booths • Speakers* User Groups•TRS-80 is a Trademark of Tandy Corporation

For Registration, Exhibitor or Fleamarket

Information Contact:

KENGORE CORPORATION

3001 Route 27 • Franklin Park, NJ 08823

(201) 297-2526

8% OVER COST

HP-85'S $2540.00

HP-83's $1760.00

HP-9895 Dual 8" Drives $5300.00

HP-8292 Dual 5" Drives $1960.00

HP-7225B Plotter $1720.00

Apple II + Computers $1090.00

LOBO Disc Drives $ 395.00

EPSON MX-70 Printers

with Apple 1(0 $ 450.00

IDS 445G Printers $ 699.00

NEC Spinwriters

with Tractors $2560.00

IDS 460G Printers $1099.00

IDS 560G Printers $1330.00

C ITOH Starwriter 25's $1300.00

CCS 300 Dual 8" Drive computer with

64K RAM, OASIS, CP/M 2.4MB Disc

memory, 2 serial ports, 1 parallel

port and a Televideo

910 CRT Call for price

CDC Lark Subsystems Call for price

Circle 199 on inquiry card.

Circle 209 on Inquiry card.

FULLYAUTOMATEDBARCHARTS

Use the TBAR program with yourCP/M system and Diablo printer toproduce fully automated bar-charts. Produce professionalquality charts in two colors withmany special symbols andfeatures.

M

A

I BEGIN »l ▼contract Award

I PHASE 1 I ■■ HUH inu

I PHASE 2 I JBJ ▲

Price: $175.00

JMCA Software, Inc.

4717 University Dr., NW

Suite 106

Huntsville, AL 35805

Heath owners

%%ftn

u

ft

ftft

'%%

ft%%ftftftft

Uft

Percom'sDouble-DensityDisk ControllerAvailable Soon!

Under

$300

See our full-page adfor Z drives in this issue.

PERCOM:

Quality disk drive systemssince 1977.

HOBBY ROBOTICS'

Shoppers Mart

For the SERIOUS Hobbyist -

Hobby Robotics' Parts Supplier Direc-tory. Chock-lull of names, addresses,phone numbers you want for hard-io-find paris. systems, bulld-your-own-robot info Only S3.50. Get yours now!

exiertdable armralcd at 15 lbs., gihands. Manual onl$25.00. refundable witfirst purchase.

HOBBY

ROBOTICS' ROBOT BASE

Ready to roll! I Clly_

ONLY S495 llncludu ahlpplnQli Slate _

HOBBY ROBOTICS

i 5070-E Buford Highway

| Norcross. Ga. 30071 404/448-0190

I Please send items checked below:

I _ Oil Newsletter [ RU-2 Manual[ Paris Directory . Hobol BaseI FREE*. Hoeby Robotics Catalog.*FREE

I Total Enclosed S l.nctutJes snipping

rsonai Cneck ._ Castiters CtiectJM Oslercnaroe _. Bank American]

-E.p

HOBBY ROBOTICS

5070-E Bulord Highway • Norcross, Ga. 30071 • 404/448-0190

Circle 182 on Inquiry card.

Circle 288 on Inquiry card.

Circle 161 on Inquiry card.

CHIPS

'&

DALEZ1

u

THE INFLATION FIGHTERSI_RAM —

4116200ns8/$16.25

2114L300ns8/M8.45

4164 200ns S27.00

— EPROM —

2716<5V)450ns8/$5.35ea. $5.75 ea.2732(5v)450ns8/«13.50ea. $14.50 ea.

We buy from Manufacturer's AuthorizedDistributors. All Chips are fullyGuaranteed. Call for quantity pricing.

Please allow up to 3 wks. for personal checks to

clear.

Add 52.50 Shipping & HandlingC.O.D. S3.00. Wash, residents add 5.4% Sales Tax

CHIPS & DALEP.O. Box 3 1607

Seattle. Wash. Zip 98103 Master Charge1-206-524-9126 VISA accepted.

C C. WRITERTRS-80*Color ComputerWORD PROCESSING

USER MODIFIABLE EX. BASIC H/PASEFORMATTING, MOVE, TABS, DELETIONINSERTION, GLOBAL SEARCH & EDITCENTERING, INDENTING, PAGE PAUSEASCII CODES, JUSTIFY, 32K OPTIONTHIS AD PREPARED WITH C.C.WRITERDiat:TRANSFORMATION TECHNOLOGIESITRS-80 is a TM of Tandy Corp.

*30 Check or M.O. to

C. C. WRITER

194 Lockwood Ln.

Bloomingdale,IL6OIO8

MEMOREX

FLEXIBLE DISCS

WE WILL NOT BE UNDER-SOLD!! Call Free (800)235-4137

for prices and information. Dealerinquiries invited and C.O.D.'saccepted.

PACIFICEXCHANGES

100 Foothill BlvdSan Luis Obispo,CA 93401 In Cal.call (800) 592-5935or (805) 543-1037

Circle 60 on Inquiry card.

Circle 363 on inquiry card.

Circle 278 on inquiry card.

vc/L.

ELECTRONICS

INTEGRATED CIRCUITS

P.O. Box 4430XSanta Clara, CA 95054

Will calls: 2322 Walsh Ave.(408) 988-1640 TWX 910-338-2139

Same day shipment. First line parts only. Factory tested.Guaranteed money back. Quality IC's and other compo-nents at factory prices.

7JO0TT1.

:aqon

7JQ2N7iQW

rmm

TiWi74 UN

7«ZN

?«ON7442JJ?445N7447N744BMM50N7474N7J75N7485N748SN7490N

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7J123N

7J17SN74 ISDN74192N741931174221N74298!!74365N74366N74367N

7usoo m

74LS00N 29

74LS02N 23

MLSMN 35

74LS0SN a

74LS08N 3i

74LS10N 3i

74LS13N 5$

74LS14N 1 03

74LS20N 35

74LS22N 35

74LS28N 35

74LS3QN 35

74LS33N 63

74LSMN 53

741S74N 45

74LS75N 65

74LS90H 63

7JLS93N 75

7JLS95N 1 03

74LS'07N 45

74LS112N 45

74LS113N 45

74LS132N 83

74LS136N 53

74LS151N 75

74LS155N 79

741S157N ! 10

74LS162N 1 10

74LSI63N 1 10

74LS174N 1 15

74LS190N 1 J5

74LS221TI 125

74LS2S8N 1 00

74LS367H 89

LINEAR

CA3045 90

CA304G I 10

CA3081 I 80

CA30S2 » 90

CA3D89 3 40LM301AN-AH 35

LM305H 87

LM307N 35

LM308IJ i 00

LM309K 1 25

LM311HN 90

LM317T 1 65

LM317K 3 75

LM318 1 SO

LM320K-5

IM320K-I?

LM320K-I5

LM320T-5

IM32QT-E

LM320T-12

LM37QM5

LM323K-5

I.M324N

LM339N

LM340K-5

LM34QK-B

LM340K 12

IM3J0K-I5

LM3-I0K2J

LM340T-5

LM340T-8

LM340T-12

LM340T-15

LU3J0T1B

IM340I-24

LM350

IM377

LU379

LM3B0N

IM3H1

LM382

I.M709H

IM723HN

LM733N

LMM1CH

LM741N

LM747H U

IM748N

LM1303N

LMI304'

LM130S

LM13Q7

LMI3I0

LMU5B

LM2902

I.M3905

Lf.H'tO'JNM' MJsVl.irMUNt55iV

NES5MNFiGiANE566VNE567VNE570B78L057BL08

CD4026CD4027CD4028CD4029CD4030CM03SCO404OCO40J2C04043CD4044CD4046CD4049CD4050CD40S1CO406QCD4D66CD406RCO4069C04070CQ4Q71CD4072CO4073CO4075CD4Q76CD407BCO40B1CD40H2CD4M6CD4490CD4b07CD4508CD4510C04511CD4515CD4516CD451BCD4520CD4S27CD-i^SC04553CD4566CD4583CO4585CO401M74C0074C0474C1074C1474C2074C3074C4B74C7474C7674C9074C9374C1S474C16074CI7574C19274C22174C90574C90674C91J74C922A lo D CONVEflTER 7JC92374C925

MCK7

2M4L 450ns 4 00

4116 200ns 2 958 4116 200osifl 4Q

MMMS2 40

MM5230 3 00

MH53>0 9 95

MM5330 5 94

PQ4HD-3 4 00

PD411D-4 5 00

P5I01. 8 95

42Q0A 9 95

82S2S 2 90

91L02A 1 SO

HD0ia-5 G95

MM57100 4 50

GIAY3850D 1 9 95

MCMG6751A 9 959368

KEYBOARDS

SG hey ASCII leyDoam Ml

Fully assimDiea

53 ney ASCII keyBoaiO hit

Fully Bstmr

■■■■ :

t Plastic

IC SOCKETSSolder Tin Low ProllliPIN 1 UP PIN 1UP

WIRE WRAP LEVEL 3

Mela! Enclosun

29 95

S10D

1000

16 67 2B 1 00

CLOCKS

MM53H 5 5i

MM5312 3 9

MM5314 3 9i

MM5359 2 H

MM5841 14 4

MM5855 7 9

CT7010 8 9

CT7015 8 9

MM5375AA-N 3 9

MM5375AGN 4 9

720S 16 5:

7207 7 5.

720B 15 9

7209 4 9

DS0026CN 3 7

DS0056CN 3 7

MM53104 2 5'

Z 45 MICROPROCESSOR

2 35 6502 10 951 10 6504 9 95

3 00 6522 9 9535 6530 9 SO

2 MHj 4 50

4 MH* 4 25

5 MHz A 2510 MHz 4 2518 MHz 3 9020 MHz 3 9032 MHz 3 9032766 Hz 4 00

1 5.132 MHz 4 503 5795 MHz 1 20

2 0100 MHz 1 95.- [)97lb2MH: 4 3Q? 4b76 MHz 4 50■; 2768 MHf 4 50

:, imv :w! 4 50

<> 16!: MHz 4 50

5 7143 MHz 4 50

"i'il 6S536M!lz 4 50

tit 14 31B18MIIZ 4 25

IS, 18 432 MHz 4 SO

Hi 22 1184 MHz 4 50

11 95 KEYBOARD ENCODERS-"95 AY5-2376 S12 505 95 AV5-3600 17 953 95 AV5-9100 10 50

12 95 AY5-9200 16.509 95 74C922 5.50

11 95 74C923 5.50

2 90 HD0165-5 6 95

LEDS

Red T018 15

Green. Yellow T01B 20

JumrjQ Rn1 20

Green. Orange Yellow Jumoo 25

CliplMe LED MounllnD Clips 8 51 25ISDeofyred. jttito green, yellow clean

CONTINENTAL SPECIALTIES in suck

Corn[,lete Mis u'Mf jilDoj-Cles! i-SjiU

MAX-100 8 dign Fieq. Ctr. 1149 ■)■■

Complete line olAP Products in stock.

Swllches Minn Pushbutton

3 pos slideEniodei iirjf)i65-5PiralionictModel >0 Trigger

{■pjrider Kil S2;

MCCEI 150 Bui

deck Cilcnflar Kit S:

1.1 MHz Frequency

Counler Kll t

30 MHz Frequency

Counter Kll &

TRANSFORMERS6V 300 m.i

12 Voir 2 a'tip-*j.ll plus12 6 CT 2 amp12OCT 4 amp12 6 CT 8 amp12 BVCT 600 ma12V 250 ma wall plug12'/CT 250 ma wall plug24V Ct 100 ma10/ 1 2 amp wan plug1?/ 6 amp12'/500 mav.au plug

/vl'ilCN

;vm;-xn

75444CN

450

22 00

8700CJ8701CN

B750CJ 13 9b

LD130 9 95

9J00CJWF 7 43

ICL7103 9 53

ICL7107 14 25

CMOS

C04000CO40O1C04002CD400S

CO4O07

i n.i.ioai.n.'.fm

CD40TC

C 1)4011CD4012

CD4Q13CD4014CD4QI5CD40I6CD40WCD4Qt8CD401OCO4020CO4021C04Q22CD4023CO4024

B228 4 95

8251 6 95

8253 15 00

8255 5 75

8257 10 95

8259 14 95

1802CP plas 13 95

i802CPpias 17 95

1B61P 9 50

CDP1B02CD 28 95

CDP1802D 35 00

CDP1816P 7 95

UART/FIFOAY5-1313AY510H

0 Connectors RS232DB25P I

DB25S I

□E9S

DAisp ;

DA15SComplete Set

12V 1

I pwfl

9 SO

10 IS VAC B 16 VA wan plug 9 75

DISPLAY LEDS

MANI CA 270 2 90

MAN3 CC 125 39

Man;? 74 CA CA 300 I 00

DL704 CC 300 l 25

DL7Q7 0L707R CA 300 1 GO

HickokS'iDioitLEDmul'limeler 89.95

Slopwalch KilAuto Clock KllDigital Clock Kll

26.9517.9519.75

DL727 72BD1747 750FN0359JND5U0 507FND503 510FNDB00 8""

3di

iSubb

ST09

8H08T133120BT233T248T258T268T2B

2101 I

PROM

1702A 4 50

2532 19 75

2708 4 70

2716T1 8 50

2716 5VOII 6 50

8/2716 5 Volt 48.002732

210M

2102AL-4

2IQ2AN-2L

2104A.J

21Q7B-4

27588741A87488748-B8755AN82S23NB25123f;£2Si36NB2SI29N82S131•JS-313^•JS2S'j7Df/.B577' B223

55 00

HK-ifiK Eprom Kit

(less PROMSl 5B9.00Motherboard S39 00Eilender Board $15 DO

RESISTORS ■. wall 5'.10 per type 0325 per lypc 025

UJO per [ype 015U"'00 ;n- type 0'2

350 piece pack

5 pei type 6 75': watt 5'.. per type 05

DIP Switches

4'positions 95 7-posihon 1S-position 1 00 8-pOSilrcn 16-position 1 00

CA CC 500 t 90

CA CC 600 1 95

CC 357 70

CC CA 500 l 35

CC CA 500 90

CC CA BOO 2 20

80

1 25

MAN354fl CC 30 1 10

MAN4&I0 CA 4Q j 20

MAH4540 CC 40 I 20

MAN4710 CA 40 95

MAtj474Q CC 40 I 20

MAM840 CC 56 2 95

MAN6710 CA 60 1 35

MAN6740 CC 60 1 35

MA1002A. C. E 8.95

MAIOUA i 95

102P3 liintlormer 2-25

MA1012A Transloimer 2.25

4116 200ns Dynamic RAM8/S18.40

PROM Eraser

assembled. 25 PROM capacity $37.50(with timer 569.50). 6 PROM capacity OSHA/UL version $78.50 (with timer $108.50).

Z80 Microcomputer

16 bit I/O, 2 MHz clock, 2K RAM, ROM Bread-board space. Excellent for control. Bare Board$28.50. Full Kit $99.00. Monitor $20.00. PowerSupply Kit $35.00. Tiny Basic $30.00

S-100 Computer Boards

8K Static Godbout Econo HA Kit 149.0016K Static Godbout Econo XIV Kit 269.0024K Static Godbout Econo XX-24 Kit 414.0032K Static Godbout Econo XX-32 Kit 537.0016K Dynamic RAM Kit 289.00

32K Dynamic RAM Kit 328.00

64K Dynamic RAM Kit 399.00

Video Interface Kit $161.00

Color Video Kit 129.95

81 IC Update Master ManualS79.95Comp. IC data selector, 2 vol. master referenceguide. Over 51.000 cross references. Free updateservice through 1981. Domestic postage $4.75.

Modem Kit $60.00

State of the art, orig., answer. No tuning neces-sary. 103 compatible 300 baud. Inexpensiveacoustic coupler plans included. Bd. Only$17.00. Article in June Radio Electronics.

Gremlin Color Video Kit $69.95

32 x 16 alpha/numerics and graphics; up to 8colors with 6847 chip; 1K RAM at EOOO. Plugsinto Super Elf 44 pin bus. No high res. graphics.On board RF Modulator Kit $4.95

NiCad Battery Fixer/Charger Kit

Opens shorted cells that won't hold a chargeand then charges them up, all in one kit w/fullparts and instructions. $9.95

Rockwell AIM 65 Computer

6502 based single board with full ASCII keyboardand 20 column thermal printer. 20 char, alphanu-meric display, ROM monitor, fully expandable.$405.00. 4K version $450.00. 4K Assembler$85.00, 8K Basic Interpreter $100.00.

Special small power supply for AIM65 assem. inframe $54.00. Complete AIM65 in thin briefcasewith power supply $499.00. Molded plasticenclosure to fit both AIM65 and power supply$47.50. Special Package Price: 4K AIM, 8K Basic,power supply, cabinet $625.00.

AIM65/KIM/VIM/Super Elf 44 pin expansionboard; 3 female and 1 male bus. Board plus 3connectors $22.95.

60 Hz Crystal Time Base Kit $4.40

Converts digital clocks from AC line frequencyto crystal time base. Outstanding accuracy.

Video Modulator Kit $9.95

Convert TV set into a high quality monitor w/oaffecting usage. Comp. kit w/full instruc.

Multi-volt Computer Power Supply

8v 5 amp. r18v .5 amp. 5v 1.5 amp. -5v.5 amp, 12v .5 amp, -12v option. =5v. +12vare regulated. Basic Kit $35.95. Kit with chassisand all hardware $51.95. Add $5,00 shipping. Kitof hardware $16.00. Woodgrain case $10.00.$1.50 shipping.

RCA Cosmac 1802 Super Elf Computer $106.95

Compare features before you decide to buy anyother computer. There is no other computer onthe market today that has all the desirable bene-fits of the Super Elf for so little money. The SuperElf is a small single board computer that doesmany big things. It is an excellent computer fortraining and for learning programming with itsmachine language and yet it is easily expandedwith additional memory, Full Basic, ASCIIKeyboards, video character generation, etc.Before you buy another small computer, see if itincludes the following features: ROM monitorState and Mode displays; Single step; Optionaladdress displays; Power Supply; Audio Amplifierand Speaker; Fully socketed for all IC's; Real costof in warranty repairs; Full documentation.The Super Ell includes a ROM monitor for pro-gram loading, editing and execution with SINGLESTEP for program debugging which is not in-cluded in others at the same price. With SINGLESTEP you can see the microprocessor chip opera-ting with the unique Quest address and data busdisplays before, during and after executing in-structions. Also, CPU mode and instruction cycleare decoded and displayed on 8 LED indicators.An RCA 1861 video graphics chip allows you toconnect to your own TV with an inexpensive videomodulator to do graphics and games. There is aspeaker system included for writing your ownmusic or using many music programs alreadywritten. The speaker amplifier may also be usedto drive relays for control purposes.A 24 key HEX keyboard includes 16 HEX keys

plus load, reset, run, wait, input, memory pro-tect, monitor select and single step. Large, onboard displays provide output and optional highand low address. There is a 44 pin standardconnector slot for PC cards and a 50 pin connec-tor slot for the Quest Super Expansion Board.Power supply and sockets for all IC's are in-cluded in the price plus a detailed 127 pg. instruc-tion manual which now includes over 40 pgs. ofsoftware info, including a series of lessons tohelp get you started and a music program andgraphics target game. Many schools and univer-sities are using the Super Elf as a course of study.OEM's use it for training and R&D.Remember, other computers only offer Super Elffeatures at additional cost or not at all. Comparebefore you buy. Super Elf Kit $106.95, Highaddress option $8.95, Low address option$9.95. Custom Cabinet with drilled and labelledplexiglass front panel $24.95. All metal Expan-sion Cabinet, painted and silk screened, withroom for 5 S-100 boards and power supply$57.00. NiCad Battery Memory Saver Kit$6.95.All kits and options also completely assembledand tested.

Questdata, a software publication for 1802 com-puter users is available by subscription for$12.00 per 12 issues. Single issues $1.50. Is-sues 1-12 bound $16.50.

Free 14 page brochure.

of complete Super Elf system.

Moews Video Graphics $3.50. Games and Music$3.00, Chip 8 Interpreter $5.50.

Super Expansion Board with Cassette Interface $89.95

This is truly an astounding value! This board hasbeen designed to allow you to decide how youwant it optioned. The Super Expansion Boardcomes with 4K of low power RAM fully address-able anywhere in 64K with built-in memory pro-tect and a cassette interlace. Provisions havebeen made for all other options on the sameboard and it fits neatly into the hardwood cabinetalongside the Super Elf. The board includes slotsfor up to 6K of EPROM (2708, 2758, 2716 or Tl2716) and is fully socketed. EPROM can be usedfor the monitor and Tiny Basic or other purposes.A IK Super ROM Monitor $19.95 is available asan on board option in 2708 EPROM which hasbeen preprogrammed with a program loader/editor and error checking multi file cassetteread/write software, (relocatable cassette file)another exclusive from Quest. It includes registersave and readout, block move capability andvideo graphics driver with blinking cursor. Break

Quest Super Basic V5.0

A new enhanced version of Super Basic nowavailable. Quest was the first companyworldwide to ship a full size Basic for 1802Systems. A complete function Super Basic by

Ron Cenker including floating point capabilitywith scientific notation (number range±.17E3a), 32 bit integer ±2 billion; multi dimarrays, string arrays; string manipulation; cas-sette I/O; save and load, basic, data and ma-chine language programs; and over 75 state-ments, functions and operations.

points can be used with the register save featureto isolate program bugs quickly, then follow withsingle step. If you have the Super ExpansionBoard and Super Monitor the monitor is up andrunning at the push of a button.Other on board options include Parallel Inputand Output Ports with full handshake. Theyallow easy connection of an ASCII keyboard to theinput port. RS 232 and 20 ma Current Loop forteletype or other device are on board and if .youneed more memory there are two S-100 slots forstatic RAM or video boards. Also a 1K SuperMonitor version 2 with video driver for full capa-bility display with Tiny Basic and a video interfaceboard. Parallel I/O Ports $9.65, RS 232 $4.50,TTY 20 ma l/F $1.95, S-100 $4.50. A 50 pinconnector set with ribbon cable is available at$15.25 for easy connection between the SuperElf and the Super Expansion Board.Power Supply Kit for the complete system (seeMulti-volt Power Supply).

New improved faster version including re-number and essentially unlimited variables.Also, an exclusive user expandable commandlibrary.

Serial and Parallel I/O included.Super Basic on Cassette $55.00.

Type-N-Talk by Votrax

Text to speech synthesizer with unlim-ited vocabulary, built-in text to speechalgorithm, 70 to 100 bits per secondspeech synthesizer, RS232C interface$345.00.

1802 16K Dynamic RAM Kit $149.00

Expandable to 64K. Hidden refresh w/clocks up to 4MHz w,no wait states. Addl. 16K RAM $25.00Tiny Basic Extended on Cassette $15.00

(Added commands include Stringy, Array, Cas-sette I/O etc.) S-100 4 slot expansion $ 9.95Super Monitor VI.I Source Listing $15.00

Elf II Adapter Kit $24.95

Plugs into Elf II providing Super Elf 44 and 50 pinplus S-100 bus expansion. (With Super Ex-pansion). High and low address displays, stateand mode LED's optional $18.00.

Super Color S-100 Video Kit $129.95

Expandable to 256 x 192 high resolution colorgraphics. 6847 with all display modes computercontrolled. Memory mapped. 1K RAM expanda-ble to 6K. S-100 bus 1802,8080,8085, Z80 etc.Dealers: Send' for excellent pricing/marginprogram.

Editor Assembler $25.00

(Requires minimum of 4K for E/A plus user

source)

1802 Tiny Basic Source listing $19.00

Super Monitor V2.0/2.1 Source Listing $20.00

TERMS: $5.00 min. order U.S. Funds. Calif residents add 6% tax.

110.00 mln. BankAmerlcard and Master Charge accepted. $1.00 insurance optional.Postage: Add 5%. CO.O. $10.00 min. order.

FREE: Send lor your copy of our NEW 1981QUEST CATALOG. Include 48c stamp.

Circle 308 on inquiry card.

BYTE September 1981 455

NEW 16K-RAMPERSONAL COMPUTER

$00000 FACTORY SALEC.C.<3 PRICE

For $229™ you get the new InteractModel "R" Computer, 16K-RAM,2K-R0M, 8080A Microprocessor,color, sound, full 53 keyboard, highspeed cassette, AC adapter, R.F.Modulator, Black Console Case, 90days parts and labor warranty,owners' guide, FCC approved.15 DAY FREE TRIAL Return within15 days complete and undamagedfor refund of purchase price.

PROTECTO ENTERPRIZESBOX 550, BARRINGTON, IL 60010PHONE 312/382-5244TO ORDER

MULTIBUS for SALE:

SBC86/12A $1200

SBC 80/30 $ 450

SBC 064 $ 900

SBC 604 $ 85

SBC 614 $ 85

BLC556 $ 175

Much more in stock. We buy/swap/sell any/all computer systems. Add2% for shipping/handling.

Oracle Electronics& Trading Co., Inc.

467 Hamilton Ave., Suite 22

Palo Alto, CA 94301

(415) 321-7650

RS-232 PROBLEMS?

LET THE RS-232 TESTER HELP YOUSOLVE YOUR COMPUTER INTERFACEPROBLEMS. DESIGNED TO CONNECTIN SERIES WITH ANY RS-232 INTER-FACE, IT DISPLAYS THE STATUS OFSEVEN OF THE MOST IMPORTANTLINES: TRANSMIT DATA, RECEIVEDATA, REQUEST TO SEND, CLEAR TOSEND, DATA SET READY, CARRIERDETECT, AND DATA TERMINALREADY. THE RS-232 TESTER RE-QUIRES NO POWER AND MAY BELEFT IN THE LINE PERMANENTLY.

$39.95 POST PAIDB & B ELECTRONICS

BOX 475/MENDOTA, IL 61342

Circle 301 on Inquiry card.

Circle 133 on Inquiry card.

Circle 35 on Inquiry card.

Sr

n rem auRijTy camPonErvrs

l_U Q & R

48 HOUR BOARD EXCHANGE WARRANTY ONGODBOUT 6 SYSTEMS GROUP COMPUTERSA tested duplicate beard will be sent viaUPS BLUE LABEL Service for one year.GODBOUT Systems include DMA CPU,64K-10MHzRam (expandable to 512K) DMA Disk 1 Con-troller, 2 serial ports, IEEE S-100 SingleUnit 12 Slot Mainframe & Dual 8" Drive Cabwith (2) Shugart SOlR's (One Megabyte)CPU Z 6MHz Z80 System w/CPM*2.2 3995.

CPU 6MHz 8088/8085 System w/CPM*2.2 4095.CBASIC 86 275. PASCAL M 86 225.

SYSTEMS GROUP 2B00 Series COMPUTERS with4MHz Z80,64K Ram, 2 serial & 2 par. portsCPM* System (2) Shugart 801R's 1MB 3995.CPM* System (2) NEC 1160's 2MB 4695.

CPM* System 1 NEC 1 Hard Disk 10MB 7095.MPM* System 2 NEC 1160's 128K 2MB 5584.CPC2811 4MHz Z80 365. FDC2801 Disk 343.Word Star 300. DBASEII A.T. 585.

Godbout 6MHz Z80 308. Disk 1 DMA AST 386.Epson MX80 par 473. Shipping ExtraWE BEAT ANY BONAFIDE PRICE ON TELEVTDEOSYSTEM I,II, OR III . Call for priceQ,T. SYSTEM+I 64K, (2)801R's Z80A 2995.TELEVTDEO 910,912,920, & 950 Best PricesALL PRICES & SPECS, SUBJECT TO CHANGECPM* is Registered r.M. of Digital Research

*pd aax. qsi ^Mut

'l^ESTrhinSTEF? CR q5b"feJi2

• "714 ^D^S |-|Hfc3

ISIS <—> CP/M®

Full bi-directional file transfer capabilitiesare provided in the ISIS-CP/M utilitiespackage. Written in machine languageand running under CP/M, these utilitiespermit the CP/M user to read or write filesdirect to/from an ISIS Diskette. They willrun under any version of CP/M without re-gard to diskette density. The completepackage is $250.00 including user's man-ual. Write for free brochure on other CP/Msoftware.

SOUTHERNCOMPUTERSYSTEMS, INC.

P.O. Box 3373ABirmingham, AL 35255(205)933-1659

Serial Printer Interface

(RS232C) lor

L APPLE II"

only "179 i

assembled'tesled

burned in/docum

• Powerful ON BOARD SOFTWARE provides-TOP OF FORM & AUTO PAGING

-LIST formal lor program listings (inserts I or 2blank lines after any user specified program line)-"HARD COPY" reproduces screen text on printer-INPUT from printers with keyboards

• 32 DIP SWITCH levers select ALL printer interfaceparameters (columns/line lines'page verticalmargins and more)

•BAUD rates between 70 and 1500

• Output functions selected via ATTRACTIVE colorcoded CONTROL PANEL Hits under keyboard)

•Control panel and 7 ft printer cable includedORDER NOW or send for MORE INFORMATION

RADIX, Inc. JCO residents add 3°° sales lax

P O Box 3465 Foreign orders add 10%

Littleton CO 80161 MC VISA COD MO

1303) 985-4152 Personal Check ladd 3 wks)

■ registeied trademark of Apple Computer Inc

Circle 329 on Inquiry card.

Circle 333 on inquiry card.

Circle 315 on inquiry card.

68KFORTH

New SYSTEMS LANGUAGE forERG 68-696 CPU andMotorola's KDM boarc. 0/S,Compiler, Monitor, Assembler,Interpreter, Virtual Memory,Screen Editor, DBL PrecisionArithmetic and more.FORTH-79 Standard Vocabu-lary.

$795

Empirical Research Group, Inc.POBox 1176

Milton, WA 98354206-631-4855

IC-IRS will Find It

ICIRS $37.50 1980CMDB $29.95

IC-IRS by siand Cybernetics Is THE Information RetrievalSyatam for Indexing and retrieving entries with largeamounts ol FREE FORM TEXT, such as ABSTRACTS;CORRESPONDENCE FILES (with complete letters); At-torney's CASE NOTES, CONTRACTS, WILLS; MD'S andScientist's JOURNAL ARTICLES; or any other similartype of Information. EASY TO USE.

COMPUTERIZE your CARD FILES or MAIL LISTS.

IC-IRS runs as a ".com" lile on CP/M* compatiblesystems with 2 disk drives and 32K memory. IC-IRS Iswritten In CONVERS for fast execution. It searches the984 entry 1980 COMPUTER MAGAZINE ARTICLE DATABASE In 25 seconds using combinations ol KEY WORDSwith up to 65 "and"s and 32 "or"s.

Get IC-IRS and the 1980 COMPUTER MAGAZINE ARTI-CLE DATA BASE (1980 CMDB) on standard 8"SD disks or5 1/4" disks In several popular formats.

IC-IRS 2.07 with manual = $37.50 + $2.50 postage.1980 CMDB = $29.95 (no postage with IC-IRS)

Call (512) 2S8-S310 and use your MASTERCARD or VISA,

use the bingo card or write to:

FYI, INC.

P. O. Box 10998 #615

Austin, Texas 78766

CP/M is a registered irademark ol Digital Research

LOWEST POSSIBLE PRICESBEST POSSIBLE WARRANTY

model III 16K

fisaasa^agCT 5

colorcomputer 4K

$310

call TOLL FREE 1-BOO-343-8124

rmnnuter245A Great Road

***l"'»*V^a Littleton. MA 01460

plus*

Write for yout IJ1UO 617-486-3193free catalog.

Circle 139 on inquiry card.

Circle 146 on Inquiry card.

Circle 77 on Inquiry card.

Ml

CROPROCESSOi

R SUPPORT /.(

:/s

WE GUARANTEE FACTORY PRIME PARTS

2716 EPROM 1-9 10&

IID

2708 EPROM

3 SUPPLY

2732 EPROM

1-9

10&

HITACHI

INTEL

MOTOROLA

+5 7.00 6.00+5 9.50 8.00+5 7.00 6.00

AMERICAN MICRO DEVICES

AM2708DC1-24 25-99 100&UP

INTEL

MITSUBISHI

NEC

UP

17.00 16.00 |16.00 15.0016.00 15.00

NATIONAL

+5 7.00 6.00

3.50 3.20

2.90

Tl 3 Supply 7.50 6.00

16K x 1 DYNAMIC RAM

2114L STATIC RAM

74LS SPECIAL

NEC UPD1-31 2.5032-99 2.30

416C-2 200NS100-499 2.10500 & UP 1.90

31- 100

1Kx4 1-31 99 &UP

HITACHI 200NS 2.85 2.60 2.35

INTEL 200NS 3.00 2.85 2.70

NEC 250NS 3.00 2.85 2.70

LS175LS240LS241LS244LS245LS373

.751.151.151.001.951.15

Z80-P10 6.00

8755 49.95

4050 .69

4531

.99

74C925 6.95

74LS107 .45

74LS244

1.00

Z80A-P10 7.10

4000 .35

4051 1.10

4532

1.25

74LS0O .35

74LS109 .45

74LS245

1.95

Z80-CTC 6.00

4001 .35

4052 1.10

4539

.99

74LS01 .28

74LS112 .49

74LS247

1.10

Z80ACTC 7.10

4002 .35

4053 1.10

4543

1.99

74LS02 .28

74LS122 .55

74LS248

1.10

Z80-DMA 18.50

4006 1.39

4055 3.95

4553

3.50

74LS03 .28

74LS123 1.19

74LS249

1.69

Z80A-DMA 22.50

4007 .29

4056 2.95

4555

.75

74LS04 .39

74LS125 1.35

74LS251

1.79

Z80-S10/0 18.50

4008 1.39

4059 9.95

4556

.75

74LS05 .28

74LS126 .89

74LS253

.98

Z80A-S10/0 22.50

4009 .49

4060 1.39

4581

1.99

74LS08 .39

74LS132 .79

74LS257

.98

Z80-S10/1 18.50

4010 .49

4066 .75

4582

1.01

74LS09 .39

74LS136 .59

74LS258

.98

Z80A-S10/1 22.50

4011 .35

4068 .35

4584

.55

74LS10 .28

74LS138 .89

74LS259

2.95

Z80-S10/2 18.50

4012 .29

4069 .35

4585

.99

74LS11 .39

74LS139 .89

74LS260

.69

Z80A-S1 0/2 22.50

4013 .49

4070 .49

4702

9.95

74LS12 .39

74LS145 1.25

74LS261

2.49

3205 3.95

4014 1.39

4071 .35

74C00

.39

74LS13 .47

74LS148 1.49

74LS266

.59

3242 10.00

4015 1.15

4072 .35

74C02

.39

74LS14 1.25

74LS151 .79

74LS273

1.75

8155 11.25

4016 .59

4073 .35

74C04

.39

74LS15 .39

74LS153 .79

74LS275

4.40

8185 29.95

4017 1*19

4075 .35

74C08

.49

74LS20 .26

74LS155 1.19

74LS279

.59

8185-2 39.95

4018 .99

4076 1.29

74C10

.49

74LS21 .3B

74LS156 .99

74LS283

1.10

8202 45.00

4019 .49

4078 .35

74C14

1.65

74LS22 .38

74LS157 .99

74LS290

1.29

8205 3.95

4020 1.19

4081 .35

74C20

.39

74LS26 .39

74LS158 .75

74LS293

1.95

8212 2.00

4021 1.19

4082 .35

74C30

.39

74LS27 .39

74LS160 .98

74LS295

1.10

8214 3.95

4022 1.15

4085 1.95

74C32

99

74LS28 .39

74LS161 1.15

74LS298

1.29 I

8216 1.85

4023 .38

4086 .79

74C42

1.85

74LS30 .26

74LS162 .98

74LS324

1.75 I

8224 2.65

4024 .79

4093 .99

74C48

2.39

74LS32 .39

74LS163 .98

74LS347

1.95

8226 1.85

4025 .38

4099 2.25

74C73

.85

74LS37 .79

74LS164 1.19

74LS348

1.95

8228 5.00

4026 2.50

4104 1.99

74C74

.85

74LS38 .39

74LS165 .89

74LS352

1.65

8238 5.45

4027 .65

4501 .39

74C85

2.49

74LS42 .79

74LS166 2.49

74LS353

1.65

8243 4.65

4028 .85

4502 1.65

74C89

4.95

74LS47 .79

74LS170 1.99

74LS363

1.49 I

8251A 5.55

4029 1.29

4503 .69

74C90

1.85

74LS48 .79

74LS173 .89

74LS365

.99 I

8253 9.85

4030 .45

4505 8.95

74C93

1.85

74LS51 .26

74LS174 .99

74LS366

.99 I

8255A 5.40

4031 3.25

4506 .75

74C95

1.85

74LS54 .35

74LS175 .75

74LS367

.73 I

8255A-5 5.40

4032 2.15

4507 .95

74C107

1.19

74LS55 .35

74LS181 2.20

74LS368

.73 I

8257 9.25

4033 2.15

4508 3.95

74C151

2.49

74LS73 .45

74LS190 1.15

74LS373

115 I

8257 5 9.25

4034 3.25

4510 1.39

74C154

3.50

74LS74 .59

74LS191 1.15

74LS374

2.75 I

8259A 7.30

4035 .95

4511 1.39

74C157

2.10

74LS75 .68 _

74LS192 .98

74LS375

.69

8271 60.00

4037 1.95

4512 1.39

74C160

2.39

74LS76 .45"

74LS193 .98

74LS377

1.95

8275 32.95

4040 1.29

4514 3.95

74C161

2.30

74LS78 .65

74LS194 1.15

74LS385

1.95 I

8279 10.80

4041 1.25

4515 3.95

74C163

2.39

74LS83 .99

74LS195 .95

74LS386

.65 I

8279-5 10.80

4042 .95

4516 1.69

74C164

2.39

74LS85 1.19

74LS196 .89

74LS390

1.95 1

8282 6.70

4043 .85

4519 .99

74C173

2.59

74LS86 .45

74LS197 .89

74LS393

1.95 1

8283 6.70

4044 .85

4520 1.39

74C174

2.75

74LS90 .75

74LS221 1.49

74LS395

1.70 1

8284 5.85

4046 1.75

4522 .99

74C175

2.75

74LS92 .75

74LS240 .1.15

74LS399

2.95 I

8286 6.70

4047 1.25

4526 1.15

74C192

2.39

74LS93 .75

74LS241 1.15

74LS424

2.95 1

8287 6.70

4048 .99

4527 1.75

74C193

2.39

74LS95 .88

74LS242 1.95

74LS668

1.75 1

8288 25.40

4049 .69

4528 .99

74C195

2.39

74LS96 .98

74LS243 1.95

74LS670

2.29 1

8289 49.95

INCH

MINIMUM ORDER $10.00

JDE $3.00 FOR U.P.S. GROUND

HANLEY ENGINEERING I

(206) 643-0792 I1 3400 NORTH UP WAY #22BELLEVUE, WASHINGTON 98005

$4.00 1

Wash

rOR UPS BLUE or 1 st CLASS MAIL

ington State Add 5.4% Sales Tax

FOR T

HE FINEST IN MICROPROCESSOR SUPPOR1

r i.e.1

s

Circle 156 on inquiry card.

BYTE September 1981 457

6809 Small C Compiler

■ Generates assembly language source output

■ Requires only 16K memory

■ Library functions in source code

■ Generates position independent code

■ Supports most C functions

■ Generates ROMmable code

INTRODUCTORY PRICE $75specify 5 or 8 inch diskette SSB or FLEX

TERMS: Check or Money Order. California residentsadd 6%. C.O.D. orders add S3.50 shipping & handling.

DOGGER'S GnOWinGBlSVSTEffV

POST OFFICE BOX 305 SOLANA BEACH.CA 92075

714-755-4373

Available soon: Basic to C Converter

LABELS

15/16"x3*4"1 up - pin feed

white pressuresensitive

PRICE INCLUDES SHIPPING

Packed 5M per box - Min. order 1 box -S14.75Check with order - Mass Residents add 5% Sales Tax

CHECK-MATE

P.O. Box 103, Randolph, MA 02368Telephone: 617-963-7694

PROFESSIONALMICROCOMPUTER

THE BEST VALUE ON THE MARKET

• Z80 4MHZ • 54K RAM

• DUAL 8" DRIVES • 1.2 MB STORAGE

• 2 SERIAL I/O • 2 PARALLEL I/O

• OPERATING SYSTEM AND UTILITIESMICRO BUSINESS ASSOCIATES. INC.500 SECOND STREET

SAN FRANCISCO. CA 94107415-957-1343

Circle 126 on inquiry card.

Circle 58 on Inquiry card.

Circle 217 on Inquiry card.

DATAP0INT

1134 Diskette Syitems

16k Processor with Four Diskettes(1 Megabyte). 80 CPS MatrixPrinter. Nationwide maintenanceavailable.

$2,645

SOFTWARE AVAILABLE

DISK OPERATING SYSTEM

SORT UTILITY

ISAM UTILITY

ALSO AVAILABLE FOR 5250 EACH.

A/P. A/R, GENERAL LEDGER, PAYROLL, TIME

ACCOUNTING, AND INVENTORY

AMERICAN COMPUTER EXCHANGE

100 N. MAIN ST. BOX 52

CHAGRIN FALLS, OH 44022

216-247-2100

DIGITAL PROPORTIONALCONTROLLER

7 BIT TTL/CMOS INPUT

OPTICAL ISOLATION

INTERFACE COMPUTERS TO MOTORS,HEATERS, LAMPS

120 VAC 240 VAC 15 AMP

Q§ 3715 WHITSELL AVE.PALO ALTO, CA 94306(415) 493-0779

BIBLIOTEK

The BibliographicManagement System

• Includes journals, books and symposia(patents, technical reports, governmentdocuments available soon!)

• A minimum of 500 references per bibliography

• Rapid citation entry through multi-page videoforms

• Search by authors, titles, editors, dates and/orkeywords

• User defined output formats

• Requires 48K Apple II, ROM Applesoft & twodrives

• $300.00

Scientific Software Products

3171 Donald AIndianapolis, lis. ...

(317) 286-0467

IN residents add 4% tax p•Apple II and Appiesoli are l

Dealer inquiries welcome

ol Apple Computer Co.. IncQc Accepted

Circle 19 on inquiry card.

Circle 98 on inquiry card.

Circle 320 on Inquiry card.

FULL PERFORMANCE CP/M* computer$1995 list

SI

dealer-distributor discounts

\ Afspa Computer, Inc.

5215 Scotts Valley Drive

Scotts Valley, CA 95066

(408) 438-3326

"trademarks of Digital Research, Inc.

FREE!

1981

DISCOUNT

ELECTRONICS

CATALOG

JOIN THE PAK!

Send for our Free catalog and become a

exciting catalog seventimes a year. We offerPenny Sales, FreePremiums and Lo

53

Low Prices on a wide variety ofElectronic Products such as Computer Periph-erals, integrated Circuits, Speakers, AudioEquipment, Rechargeabf-"ucls, Semiconductors, and much, much more!Take advantage ol our 25 years as America'sforemost Supplier of discount electronics.

POLY PAKS, INC.

P.O. BOX 942, BT9VSAYNNFIELD, MA. 01940

iPEX MEW!

interface Converts

Your Typewriter

into Printer

• Finest print quality *Lowcost

■ Easy Installation • Quick delivery

• FIE IBM SELECTRIC* typewriter with no modification.

• For TRS-80*, Apple*, or any parallel or RS232 port.

• write or phone for more Information, todayl

— U.S. and worldwide sales —

INTERNATIONAL INC.

16140 valerlo St.

Van Nuys, CA 91406 USA

TEL 213/781-0020 TLX/TWX: 910-495-1767

iPEX

Circle 15 on Inquiry card.

Circle 294 on Inquiry card.

Circle 176 on inquiry card.

WE WILL NOT BE UNDERSOLD

DISK DRIVES

FOR TRS-80* Model I

CCI-100 51/.", 40Track (102K) $299

ADDON DRIVES FOR ZENITH Z-89CCI-189 5 VI", 40Track(102K) $394

Z-87 Dual 51/i" system $995

External card edge and power supply included. 90 day warranty/oneyear on power supply.

RAW DRIVES

5V4"TEACorTANDON

$CALL POWER SUPPLIES $CALL

DISKETTES - box of 10

5'/." Maxell $40

8" Maxell $45

PLASTIC FILE BOX-Holds 505V«" diskettes

PLASTIC LIBRARY CASE 51/i" $3.00

HEAD CLEANING DISKETTE

FLOPPY SAVER $11.95

16K RAM KITS

200ns for TRS-80,*Apple II, (specify):

SYSTEM SPECIAL

Apple II Plus 48K w/drive and controller. Epson MX-80 printer andinterface. SUP-R Mod RF Modulator: List $2965 You Pay $2299

BASF/VerbatimBASF/Verbatim

RINGS

2 for $37Jumpers

$26.95$36.00$19.00$ 4.00$25.00$ 6.95

$19

$2.50

COMPUTERS/TERMINALS

ARCHIVES 64K, 2-Drives, 77 Track

ALTOS ACS8000 Series

ZENITH 48K, all-in-one computer

ZENITH Z-19

TELEVIDEO 910 $559 920C $ 729

IBM 3101 Display Terminal

ATARI 400 $ 429

MATTEL INTELLIVISION

APPLE PERIPHERALS

950

800

$CALL$CALL$2200$ 725$1039$1189$ 795$ 259$CALL

S-100 CALIFORNIA COMPUTER SYSTEMS

MAINFRAME

Model 2200A

Z80 CPU

Model 2810

MOTHERBOARD

Model 2501

16K STATIC RAM, 200ns

Model 2116C

32K STATIC RAM, 200ns

Model 2032C

64K DYNAMIC RAM

Model 2065C

FLOPPY DISC CONTROLLER

Model 2422A

EXTENDER BOARD

Model 2520K

2P + 2SI/0

Model 2718A

$349$259$106$309$619$580$345$ 52$309

PRINTERS

NEC SPINWRITER

Letter Quality High Speed Printer

R.O.

R.O. with tractor feed

KSR with tractor feed

NEC SPINWRITER 3500 Series, 5 new modelsEPSON MX-70 MX-80 MX-80FT

PAPER TIGER

Graphics &2K bufferGraphics & 2k bufferGraphics

MX100

IDS 445IDS 460IDS 560

ANADEX

OKIDATAMicroline 80Microline 80Microline 82Microline 83

CENTRONICS

C. ITOHStarwriter IStarwriter IStarwriter IIStarwriter II

DP-8000 $849

Friction & pin feed

Friction, and pin & tractor feed

Friction & pin feed feed

120 cps, uses up to 15" paper

739, new model with graphics

25 cps, parallel interface25 cps, serial interface45 cps, parallel interface45 cps, serial interface

DP-9500/01

PRINTER SPECIAL

SEIKOSHA GP-80M

MONITORS

BELL&

HOWELL

LEEDEX

List $399

$2395$2555$2795

$CALL$CALL

$ 695$ 799$ 999$1295

$ 415$ 500$ 615$ 849$ 749

$1449$1529$1829$1949

You Pay $319

9'12'13"

9'12'13"

B&W BHD911B&W $129

ColorB&WB&WColor

$329$149$219$349

SANYOZENITH

TELECOMMUNICATIONS

LIVERMORE STAR MODEM 2-year guarantee

UNIVERSAL DATA SYSTEMS UDS-103

D-CAT HARD WIRED DIRECT MODEM

AUTO-CAT Auto Answer, Direct Connect Modem

APPLE-CAT II

D.C. HAYES MICRO-MODEM

D.C. HAYES SMART-MODEM

CCI Telnet Communications Package

$195

12" Green Screen $159

12" Green Screen $23813" Color $406

12" Green Screen $129

$125$179$189$249$349$295$235$135

APPLE ACCESSORIES AND SOFTWARE

VISICALC $155.00 DB MASTER $159.00

Z-80SOFTCARD

VIDEX BOARD

KEYBOARD ENHANCER

16KCARD

APPLE JOYSTICK

SUP-R MOD

CCS CARDS

GALAXIAN

SPACE ALBUM

ASTEROIDS

FLIGHT SIMULATOR

WIZARDS PRINCESS

SARGON2

MYSTERY HOUSE $ 24.00

HIRES FOOTBALL

$259.00$259.00$110.00$169.00$ 49.00$ 25.00$CALL$ 22.9535.0017.9529.0028.00$ 29.00$ 35.00

For fast delivery, send certified checks, money orders or call to arrange direct bank wire transfers. Personal or company checks require twoto three weeks to clear. All prices are mail order only and are subject to change without notice. Call for shipping charges.

dealer (national/international) inquiries invited Send for FREE Catalogue

TO ORDER CALL TOLL FREE 1-800-343-6522

TWX: 710-348-1796 Massachusetts Residents call 617/242-3361

The CPU SHOP

5 Dexter Row, Dept. B09M

Charlestown, Massachusetts 02129

Hours 10AM-6PM (EST) Mon.-Fri. (Sat. till 5)

Technical Information call 617/242-3361Massachusetts Residents add 5% Sales TaxTandy Corporation Trademark/" Digital ResearchCircle 96 on inquiry card.

database manager

forms 80 Model I

• CREATE random access disk files15 fields or 255 bytes/recordFiles can span 4 disk drivesPassword protected file access

• Database DIRECTORY displays alluser files and their attributes

• Powerful TRAI\ISACTIONS-add,edit, read, delete & list recordsEfficient binary tree sorts

• Sophisticated QUERY with multi-key relational & logical operations

• REPORT formatter requires onlyfor user to select desired fieldsAutomatic sub & grand totalsMay be used with lower case

• Entirely MEIMU DRIVEN operation

• Extensive error trapping routines

• User oriented instruction manual

• Requires 32k — 2 disk drives

Introductory price $59.95

Visa and MasterCard accepted

mentor software

816 McLane Aue-Morgantown, VW 26505Tandy Corp. Trademark

Circle 212 on inquiry card.

EAGLES ?COWBOYS ?

RAIDERSRAMS

II you'd like lo know NOW. before the big game

Wilh PHOCAP and your TflS-80*. you can use slatislics andprobability theory io predict the results ol this week's biggames And more. PROCAP

• Gives offensive and defensive ratings for everyNational Football League team

■ Predicts range ol results and probable score (oreach game

• Allows computer matchup ol any iwo teams(Great lor playoffs1)

• Gives up-lo-lhe-minute standings, statistics,and ratings lor each NFL Division

PHOCAP is easy lo use and comes with extensive documentation

fliy S49 95number NOW Money bat

Dial (800) 543-3000. operator 400

In Ohio dial (800) 582-1364. operator 400

The Trinity Computer Group • Software Agent/Publisher

PRIAM

Disk Subsystems

and

Accessories,

(SMD interface available)lowest cost and greatest established relia-bility for H.P., DEC, Apple, Z-80, 8085 ... andso on.

We can show you how to overcome"foreign disk" warranty worries.

Special Opportunity:

14A. S-100 Power Supply Kit

Input: 95-220VAC, 50/60 Hz * ~ AOutputs: 14A@±8VDC $£u

2A@±18VDC

Includes: UL Spec. Transformer, Rectifiers,Computer Grade Capacitors. RFI line filter,and Schematics.

ADVANCED TECHNOLOGY

735 Loma Verde, Palo Alto, CA 94303

415-493-5930Send 36 ct SASE for our 16 page flyer.

Circle 10 on inquiry card.

CP/M® Compatible$GOLD DISKSZ-80 Software

Z-80 Disassembler Jk | 7S

ppdcreates assembly language source files

E-ZText $75.

ppdunique text file word processor

Bower-StewartSi Associates

POST OFFICE BOX 1389HAWTHORNE, CALIFORNIA 90250213/676-5055

TrademarkDigital Research

***********************

"COMPUTER SURPLUS**

***********************

Brand new Perkin-ElmerNo. 550 terminals

—priced ridiculously low.Call us for a quote.

CALL VICTOR CLOUGH(216)473-0866

Also buy scrap computersystems, printed circuit boards,

connectors etc. ...LARGE VOLUME ACCEPTABLE

DATA HARDWARE

701 Beta Dr. #4Cleveland Ohio 44143

DEALERS WELCOME

Circle 101 on inquiry card.

ARE WE CRAZY?

K0!, WE ARE KL0F0X, the people that bringto you a system with so many features, itcould sell for twice as much (like some ofour competitors do). We believe high qual-ity need not have a high price, and oursystems prove iti

For just 1695.00, you'll get a Z-80system with 6Uk of RAM, and up to 8k ofbank-selected PROM, The two bidirectionalparallel ports let you interface to almostanything. The basic system is equippedwith one SD 8" disk drive, but can easilybe expanded to four giving one megabyte ofon-line storage. You will have a choicebetween an 80x2*4 terminal simulating videointerface, or two serial ports, or evenboth (at an extra charge).

Our systems will run GP/M and MP/M,and we include our custom BIOS and XI0S,plus many other useful system utilities.

KJ.OFOX

PO BOX 93SAN LUIS OBISPO, CA 93406 USA

(805) 52S-7440

Note: CP/M and MP/M are both trademarks ofDigital Research of Pacific Grove, CA

Circle 366 on inquiry card.

Circle 43 on inquiry card.

Circle 185 on Inquiry card.

FACTORY PRIME STATIC RAM CHIPS

2114 Super Low Power

200ns. 1Kx4 $ 2.90

6514 CMOS 300ns. 1Kx4 $ 6.90

6116 CMOS 200ns. 2Kx8 $22.50

Add $5.00 Handling on Orders Under $200.00

FfiPTflRY PRIMP From ,fie same shipments usecl mrMl/IUni rnimt GIMIX Professional quality boards.

32KB STATIC RAM CARDS

for the SS50 and SS50C BUS

(16KB - $298.12), (24KB - 348.14)

(32KB — $398.15)

.jeW- 64KB BATTERY BACK UPN CMOS RAM CARDS

Two independently addressable 32KB

blocks, each with extended addressing.

(56KB ■ $994.56), (64KB - $1088.64)

2MHZ 6BD9 56KB SS50 SYSTEMS $2498.29

DISK SYSTEMS AVAILABLE

Gimix (5i

1337 W. 37th Place • Chicago, IL 60609(312)927-5510 • TWX 910-221-4055The Company that delivers.

Quality Electronic products since 1975.

GIMIX* and GHOST* ate Registered Trademarks el GIMIX INC.

1802fig-FORTH

high-level compiler language

10- 20X faster than BASIC

ELF II /Super ELF/Other

w/assembler-editor $60

w/macro assemb.screen-editor $80extras

on cassette/requires 12k+RAM

P.O. Boxflu.-ttn. T.78712

-312-477-22B7

EVERY

BUY, SELL OR TRADE ALL TYPES OFCOMPUTER EQUIPMENT AND SOFT-WARE (pre-owned and new) among20,000 readers nationwide in BIG(11x14") pages. Classified ads areonly 10* per word and are indexed foreasy and fast location. Subscription:$10 a year / 12 issues. Money backguarantee. Sample copy, $1.50.CamPUTSR SHOPPSRP.O. Box F-14Titusville, FL 32780(305) 269-3211MasterCard or VISA subscription orders only,call TOLL FREE 1-800-327-9920

Circle 149 on inquiry card.

Circle 145 on inquiry card.

Circle 78 on inquiry card.

sC

SONALOMPUTER3000 Family

14 display, hi-res color

sr and lower case

t popular in Japan

ures compare with Apple III

'01A CPU

V 32K RAM

osoft Basic

Doard: Numeric pad,

er programmable keys

parallel, one serial port

12A I/O

RAM, expandable to 128Kit busexpansion

31A Mini-Disksves, 143K per drive

\fl

C-8001A $1295 PC-8012A $795

3031A . . . $1295

n Discount $3200

AuthorizedDealer

QTSTEM H+

r*

SYSTEM H + and SYSTEM*Byte hard disklz Z-80A, 4 serial, 2 parallelRam useable per userA multi-user DOSup: 1 MByte floppy: Optional tape cartridge

$12,750

Call

13,250

lor

13,750

quotes

14.250

QT SYSTEM+

HZ Z-80A, 2 serial, 2 parallel

tloppies, double density

Ram. EPROM monitor for RS-232

vl 2.2

onal 6. 8, or 12 slot motherboard

anal single or double-sided floppie:

led in—just add video terminal

;S(6) ..iS(8) ..)S(12) .

, $3595 SYS+DS(6) $4495

.. 3695 SYS+DS(8) 4595

..3795 SYS*DS(12) 4695

QTMINI-YSTEM+

f5fc

ve with BJ4" floppies MINI-SYSTEM* (5'/,")

+SS(6) $2495 MSYS*DS(6j ... $2795

*SS(8) 2595 MSYS+DS(8) .... 2895

♦SS(12) 2695 MSYS+DS(12) ... 2995

QT RAM+1616K Static, S-100

< switchable RAM

jsands of happy customers

$35 4MHzKit...$180 4MHz A&T . . $165

- V

DISK Y.CKAGES

88-2 2-801R. cab., ps, fan $1250

88-22 2-Qume DT-8. cab., ps. fan 1675

88-3 Cabinet, ps. fan, cables 325

88-4 Cabinet only 58

irt801R $390

DT-8 585

i-51 250

i-52 350

QT SBC+2/400 Single Board Computer

iA. 2 or 4 MHz. switchHam. 1 parallel, 1 serialtOM monitor (specify)A, programmable timers

. $195 A&T . . . $300

STARWRITER

• Daisywheel printer.Diablo compatible

• Nationwide service

• Centronics parallel or RS-232 serial

• 25 cps or 45 cps. specify

25-P $1400 25-S $1500

45-P 1750 45-S 1850

Tractor. . $200

EPSON MX-100

• Wide carriage

• Friction, tractor, graphics

• "Correspondence" quality print

Unbeatable price $795

SEALS IS BACKSeals 64K Static S-100

• Uses Fujitsu MB8167.16K + 1 static in 20 pin

• 70ns: DMA to 14MHz

• Complete 16 bit or 8 bit flexibility

• IEEE S-100 and Cromix compatible

List $1195 Now S1050

STATIC MEMORY SYSTEMS64K Static S-100

• See ad, this issue

• Intermix RAM and EPROM

• 200ns, very low power

SMS-64K A&T $550

QT Z+80 CPU

• 2 or 4 MHz. switch

• Monitor with jump

• Serial port to 9600 baud

Kit . . . $165 A&T . . . $225

QT EXPANDABLE + REV IIS-100 64K Dynamic RAM

• 2 or 4 MHz. switch

• Bank switch, IEEE Standard

• On board refresh, 4 layer PC

• Burned in, tested.

EXP +16 $270 EXP • 48 S310

EXP + 32 290 EXP + 64 330

(Less $40—kit)

QT I/O+S-100 4 Parallel, 2 Serial

• On board crystal

• Prog, baud

• 16 prog, timers

• 8 level prog, interrupt

Brd . . . $70 Kit . . . $235 A&T . . . $375

QT SILENCE+S-100 Motherboards

• Full ground shield network

• Specify board, kit. or assembled

6-B .6-K6-A .

18-B $50 22-B

18-K 100 22-K .

18-A 140 22-A .

$25 8-B $27 12-B.

..40 S-K 55 12-K.

. .50 8-A 70 12-A.

$30. 70. 90

$75140190

QT MAINFRAMES

• 18A power supply, S-100

• Drive power supply

• Specify motherboard slots

• Specify 8", 5V." or no floppy

2-8" Floppy w/motherboard

MF8-6 $625

MF8-8 650

MF8-12 e75

2-5%" Floppy—w/Motherboard

MF5-6 $450

MF5-12 500

No Floppy—w/Motherboard

MF*12 $450

MF+18 500

MF*22 600

8

QTSINGLE' CABINET

m

• Accepts one 8" floppy

• Power supply, tan. AC filter

• 117v AC/220V AC

• Data cable, power cables

DDC+8 $175

SD SYSTEMS

20%+Discount on ^3A&T

All SD items available.

38007 Z-80 Starter Board $424

38013 VDB-8024 (60 Hz) 444

38020 Expandoram II-16K 310

38023 Expandoram II-64K 370

38025 PROM 100 248

38059 Versafloppy II (RS-232) 400

38060 Versafloppy II (VDB-8024) 400

38061 SBC-200 (VDB-8024) 376

38062 SBC-200 (RS-232) 376

Call tor kit, software, and cable prices.

CALIFORNIA tmm

COMPUTER SYSTEMS \fmm

15% Discount fc—J

All CCS items available. ^^^^

S-100

2032A 32K Static -2 MHz $561

2032B 32K Static - 4 MHz 641

2116A 16K Static - 2 MHz 297

2116B 16K Static - 4 MHz 331

2200A Mainframe 368

2210A System 1600

2422A Floppy Controller 360

2710A 4-Port Serial 289

APPLE

7114A 12K ROM/PROM Board $68

7440A Programmable Timer 97

7470A A/D Converter 102

7490A QPIB IEEE-488 255

7500A Wire Wrap Board 20

7510A Solder Tail Board 21

7520A Extender Board 25

7710A Serial Asynch Board 136

7728A Centronics Parallel Bd 105

7811 B Arith Processor - disk 355

7811C Arith Processor - ROM 355

NEC SPINWRITER 55CPS

• Receive only, serial interface

Only $2500

IDS PAPER TIGERS

#445 $710

K460G 1050

«560G 1300

TELETEK

FDC-1 Single Board Computer $685

FDC-2 Double Density Controller 325

QT S-100 EXTENDER

• With connector

Kit S30 A&T S35

CABLES

RS-232- male/male - 9 ft $24.00

RS-232 - male/male - 18 ft 29.00

RS-232 - male/female - 9 ft 29.00

^ ADDS VIEWPOINT<& Smart CRT Terminal

• 80 x 24

• Detachable keyboard

The Best for Less

$625

QT S-100CARDCAGES

• 6. 8 or 12 slot

• Accepts Silence * mothei

• With card guides

• Accepts 4" fan

• Specify with mother, with fan

6 Slot (5V.wx 10»d x 6"h)

CC+6 $24

CC+6M 90

CC+6M/F 115

8 Slot (7'/.w x 10V4d x 6"h)

CC»8 $39

CC+8M 99

CC+8M/F 134

12 Slot (11VSW x 10%d x 6"h)

CC+12 $61

CC+12M 114

CC+12M/F 149

\M

ADES

S-100

HARD DISK

• PRIAM 3350 8" Winchester

• 31 MByte with CP/M 2.2

• With S-100 controller

• Cables, cabinet, power supply

• Full line available

»S33 List $5195 Now

2 MBYTE

~~-- FLOPPY FOR

HJ|_APPLE --B^-=i

ISiiil,

• 2 double density, double sided 8" drives

• Cabinet, power supply, cable, controller

• DOS 3.3 compatible (Pascal and CP/M optional)

• This package is best, spec (or spec; price tor price.

Suggested List ... $2550 Now Only $2050

SAVE $500 CP/M Patch $75 Pascal Patch $75

ADD-ON DRIVE FOR APPLE

• Works with Apple disk controller

• Functionally identical to Apple

• Expandable to 40 track

Prairie Fire Price $375

BULK DISKETTES

• Single side, doubledensity

• Specify hard, soft, U of sectors

• Sold in hundreds

5W $215/100 8"

Library cases:

5%" $25/10 8" ....

.$275/100

$32/10

ANTI-STATIC CHAIR MAT

• 4'x5' black, hard

• With ground strap

• New religion—thousands of believers

List $185 Special $160

QT CLOCK/CALENDAR+Apple, S-100, TRS-80

(Specify)

• Date, month, year

• Day of week, leap year

• 24 hour or AM-PM

• 4 interrupt intervals

• With software

• Now with on-bowd battery

S-100/Apple/TRS $150

Floppy-Data:Card Edge

rr

.1 I _**_«

Type SD • Jade

DSC-34-1DSC-34-2DSC-34-4DSC-50-1DSC-50-2DSC-50-4

Single, mini $24.00

Dual. Mini 29.00

Quad. Mini 34.00

Single, 8" 24.00

Dual, 8" 32.00

Quad. 8" 40.00

Floppy-Data: Pin TypeCCS • Tarbell • Teletek

DSP-34-1 Single, Mini $24.00

DSP-34-2 Dual. Mini 29.00

DSP-34-4 Quad, Mini 34.00

DSP-50-1 Single, 8" 24.00

DSP-50-2 Dual, 8" 29.00

DSP-50-4 Quad. 8" 34.00

8" Floppy-DC Power

PDC-8 24" long $7.00

INTEGRATED CIRCUITS

4116 (200ns) .... $2.00

2114 (450ns| 2.00

2708 3.50

2716 (5V) ..' 6.50

2716 (5-12V) 8.00

2732 13.00

4164 (200ns) .... 25.00

Z-80A 12.95

8080A 3.50

8085A 20.00

8086-4 60.00

TMS9900 29.95

8212 3.50

8214 4.50

8228 6.00

8238 6.00

8251 7.00

8257 17.95

8295 16.50

MC14411 11.00

14411Xtal 4.95

1771B01 24.95

1791A01 37.95

S2350 7.95

N8T26 2.50

1488 1.25

1489 1.25

D3242 10.15

TMS5501 19.00

TR1602B 4.50

6845P 22.00

4118 18.95

DP8304BN 4.00

is a trademark of Apple Computer. Inc CP/M and MP/M are trademarks of Digital Research TRS-80 is a trademark of Radio Shack.

PRODUCTS

MAIL ORDER: PO Box Q, Sherman Oaks, CA 91423 Circle 39 on inquiry card.RETAIL: 15620 S. Inglewood Ave., Lawndale, California 90260(213) 970-1476 (800) 421-5150 % Block South of San Deigo Fwy.TERMS OF SALE: Cash, checks, credit cards, C.O.D. Calif, residents add 6% sales tax.

FULL ELIZA FOR YOUR MICRO!

AT LAST! A FULL IMPLEMENTATION orlhe original ELIZA program is now availableto fun on your microcomputer' Created al MIT in 1966, ELIZA has Become Ihe

a noiKJfreolfvI psychottW3p!a4 IKhC analyses each staleiienl as you type il inand then responds with ner own comment or question. Response time is virtuallyinslanlaneousand her remarks are ollen startlmgly appropriate. Designed lorunon 3 large maintrame. ELIZA has hiihcrlo been unavailable to small computerusers c<cept m rjrwally shipped down versions lacking the sophistication whichmade Ihe original program 50 fascinating. Mow, a new version possessing Ihe lullpower and range ol expression of Ihe original Is available to run on any CP(Mbased microcomputer system wiih at least aOKof RAM. Supplied as a34K COM(machine language* hie on a slandardB inch diskette. Ihe program is biting offeredlor a limited lime al the introductory price of only $26. And if you want to find oulhow she does it (or leach her to do morel, we will include the complete SourceProgr«m. wrilien in MicrosollBASlC-80, Version S.XX. lor only S2Q additional. Orderyour copy ol ELIZA today ana you II never again wonder now lo respond when one

They

Well, my hoylnenri marie me come here.

YOUR BOYFRIEND MADE YOU COME HERE - THAT'S INTERESTING.

I need some help, that much seems certain.

WHAT WOULD IT MEAN TO YOU IF YOU GOT SOME HELP?

Perhaps I could H;;irn lo r;.-i along with my mother,

TELL ME MORE ABOUT YOUR FAMILY.

DOES IT PLEASE YOU TO BELIEVE I AM AFRAID OF YOU?

My lather is afraid of everybody.

WHAT ELSE COMES TO MIND WHEN YOU THINK OF YOUR F

ARTIFICIAL INTELLIGENCE RESEARCH GROUP

921 NORTH LA JOLLA AVENUELOS ANGELES, CALIFORNIA 90046(213)656-7368 (213)654-2214 yl(\ ''

MC. VISA, and CHECKS ACCEPTED ■!"

floppy disks.

100% CERTIFIED AND TESTEDPREMIUM QUALITY

H BASF

Immediate off the shelf delivery. . .one box orquantity orders welcome.

SAVE % 40%

WE PAY SHIPPING!CALL OUR ORDER DESK NOW!

Western States: Los Angeles . . (213) 469-9661

Phoenix (602) 277-5766

Central States: Dallas (214) 988-1885

All Others: (805) 985-9824

MASTERCARD — VISA — COD.

NATIONAL DATA SUPPLIES. INC.

— Discounts Discounted —

We Feature

CP/M — Osborne — Rejas — ForthMicro-soft — Micro-Pro —Micro-AP — Fortran — S-Basic

Special Feature PackagesCP/M — Peachtree Programs

General Ledger ,

Acct. Rec— \

Acct. Payable \

Pay Roll— > $1250.00

- / Plus— Sales TanS Plus — Shipping

I nventory

Mailing Address-

This sale terminates when this ad closes.Act Now.

* PACIFIC DISCOUNT

SOFTWARE

3204-A Production Avenue

Oceanside, California 92054

Telephone (714)439-6201

Circle 28 on Inquiry card.

Circle 252 on inquiry card.

Circle 276 on inquiry card.

CROMEMCOUSERS

PMSI INTRODUCES

ICIAL nif'OHTlNG SY5UM

BANKKEEPING * REPORTER

FOR - Offers Current Cash Flow Analysis and CompleiSMALL Profit/Loss Picture for Each Month andBUSINESS Year-To-DateAdaptable to All Types of Business, Farms. PropertyManagement and Investments

FDR Provides a Unique Budget tor F3m.ly

INDIVIDUALS Expenditures for Current Month and Year To [

Supp'ies a Monthly Recap of Tax Deductible Items as Well as

Complete Listing of All Tax Deductible Items for the Entire Y

Perfect Package for CPA's. Bookkeeping SeruicService Bureaus. Banks and Savings/Loans

PMSi PROVIDES S

■ ftGI i

PRACTICAL MANAGEMENT SYSTEMS. INC

P O BOX 1301. 2900 KING STREET

JONESBORO. AR 72401

501 932 8206

-DEALER DISCOUNTS AVAILABLE-

A ATARI'

Atari 80016K 810.00 16K RAM 85.00

Atari 800 48K 950.00 Atari 850 Interlace 176.00

Atari 810 Disk 460.00 Atari 830 Modem 1 56.00

Atari 400 16K 379.00 Microsoft Basic 72.00

TELECOMMUNICATIONS PACKAGES

Base Unit, A850, A830, TeleLink I

with 800: $1150.00 with 400: $710.00

PLUS FREE NOVATION SUPERMIKE!

The Bit Bucket is a company made up of com-puter professionals. We are able to providelow prices as well as technical support. Giveus a call and find out why we consider theAtari the best home computer on the markettoday. You won't be disappointed.

The Bit Bucket

Specializing in Atari Home Computers

P.O. Box 365

Newton Highlands. MA 02161

(617)783-3144

FORTH

FOR/MAT™

SCREEN EDITOR

A MUST FOR THE SERIOUS FORTHPROGRAMMER

• All code is Forth-79standard. Each line of code isfully explained and flow-charted (Forth style) foreasy modification.

• This editor works just like the popular wordprocessors on the market except it is written in highlevel forth and is confined to the 1024 byte boundaryof a forth screen.

• There are over 20 different commands for cursorpositioning, text modification, tabs, relocating lines,spreading lines, and moving lines to other screens.

• Insert mode is toggled on and off for midstreaminsertions and deletions. Text ahead of CPis movedright during insertion and left during deletion ifinsert mode is on.

■ Column position is displayed at ali times.

• Bomb proof — all unused control codes aretrapped

• Must be used with a CRT that has cursoraddressing or with a memory mapped video.

• Send check or money order in the amount of$50.00 and receive complete source code,flowcharts, documentation, and instructions forbringing up on your system.

KV33 CORPORATION

P.O. BOX 27246TUCSON, AZ 85726(602) 889-5722

W

Circle 298 on Inquiry card.

Circle 40 on Inquiry card.

Circle 186 on Inquiry card.

EPSON

DOT MATRIX PRINTERSSUPER DISCOUNTS ON

MX-80F/T L0^fRl NOW

IN

LOWER!

LOWER! O I UUK

MX-80MX-100

We also stock direct connect cables forTRS-80, Apple, Atari, Pet or RS 232

CALL TOLL FREE

1 -800-344-7493

In CA and for service (209) 667-2888

©

AMCROTRONICS. inc.. il

ll?b N Golden Stole BvdItillaCli CoMorrwa 95380

Heath/Zenith 89 Users

I6K MEMORY EXPANSION CARD

a to make a

H/Z89 a 64Kmachine.Assembledand Tested$100.00

COMPUTER TABLES

60x28x28

$186.40

48 x 28 x 28

$162.40

Shelves Available

PRINTER STAND

$75.00

MS

■amp***

'Mint I data

systems

AUTHORIZED SERVICE CENTER

SECURED COMPUTER SYSTEMS

1201 I Aclare St. • Cerritos, CA 90701(21 3) 924-6741 Shipping not included

ANALOG** DIGITALDIGITAL** ANALOG

CONVERSION MODULES

SOFTWARECAIN CONTROL

BTliTaftlAnWl'"

amplifier - custom board test S-100 - y to lb hhzable high and low inputs gain11 to 1024 IS bii ■■■ imple and hold amplifieiannel diffefentiol 16-channcl - onalog to digitalhigh accuracy programmable gain instrumentationamplifier custom boorrj i.-,i - S 100 - 2 to 15 khzconversion time - maoblB htgh and loui inputs - gainfrum 1 ■ I05M 12-bit sample and hold amplifier8-channel differential - 16-chcvinel - onalog to digitalhigh accuracy programmable n.am mstrumsntotioinmnlihrr ciatofn board tcsl S-100 - " io IS kh.

For additional derails about trie AD-100-4 and otherfine California Data Corporation 100% individuallytested, high reliability products, circle the readerservice card number below or for faster responsewrite or call us.

CALIFORNIA DATACORPORATION

3475 Old Conejo Road, Suite C-10Newbury Park, CA 91320

(805) 498-3651

Circle 198 on Inquiry card.

Circle 326 on Inquiry card.

Circle 50 on inquiry card.

DEALS □ DEALS U DEALS

OUR BUYERS ARE IN

CONTACT WITH EVERY MAJOF

SUPPLIER AND O.E.M.

BUY HERE AT 1000 PIECE

QUANTITY PRICES

ALL MERCHANDISE 100%

GUARANTEED! 15 DAY FULL

CASH REFUND!

• • • •

D C

TO w s? MICROIVI. HP. SALES

JUST HOT STUFF

POWER SUPPLIES

If you can beat theseprices we will be trulyamazed. OEM's at 500lot pay more than this.Call or write for fullspec, sheets.

DISK POWER SUPPLIES

PRIAM-SHUGART-CENTURY-MICROPOLIS

+5V@9A |-5V@.8A I+24V @ 7A | US-384

89.00

SHUGART-SIEMANS-MPI 5%"

+5V@.5A

+ 12V@.9A

US-340

33.50

+5V @ 2A

+ 12V@4A

US-323

56.25

SHUGART-SIEMANS-CDC 8"

+5V@1A

-5V@.5A

+24V@ 1.5A

US-205

52.50

+5V@2A

-5V@.5A

+24V@3A

US-206

69.00

+5V@3A

-5V@.6A

+24V @ 5A

US-162

89.00

+5V@ 1.7A

-5V@l.5A

+24V 9 2A

US-272

69.00

+5V@2A

+ 12V@.4A

-12V(9>.4A

US-HTAA

37.50

TELEVIDEO 950

Televideo 950 -$950.00Talevideo 912C- 665.00Televideo 920C- 720.00ADDS R-25 - 710.00

Also have 920C, SOROC, \HAZELTINE, etc. Whatwe don't have is room onthis page. Call Toll Free800 number for prices.

C-ITOH PRINTER$499.00

Look closely at the

photo and see other

adds in this rag at

$995.00. Perfect units,

warranteed. Only 500 pes. Same story,

manufacturerer had too many.

S-100 CARD EXTENDER

$12.50

(Gold Contacts)

As long as there is aprice war, we will fightyour battle. Compareat your local Dept.store and buy U$ MICRO.

MEM0REX - VERBATUM - WABASH

BASF FLOPPIES

BOX OF 10 ONLY:

554"

5%"

5%"

8"

8"

8"

SOFTHARD 10HARD 16SOFT 1DSOFT 2DSOFT2DDS

$2.65 ea'2.65 ea.2.65 ea.3.25 ea.3.85 ea.5.00 ea.

w

11 EDISON DRIVE • NEW LENOX * ILLINOIS 60451CALL TOLL FREE: 1-800-435-9357 * MONDAY thru SATURDAY(ILLINOIS RESIDENTS CALL: 815-485-4002) * 8:00 a.m. to 6:30p.m.

TERMS: Prepayment - C.O.D. up to $100.00 - M/C Visa$5.00 Processing and Handling added to each order PLUSShipping Charges. Please allow personal checkto clear before shipment.

SPECIAL OF THE QUARTER SPECIALS OF THE MONTH

S1-MOD (KIT)

$189.00

m^^i

Complete S-100 12 Slot Computer. Amplesystem power with regulated power for drives.Excellent for Subsystem or Hobby use.4 hours to build. (6 conn, inch, less fans)

DUAL DRIVE SUBSYSTEM

$995.00

$195.00 w/no Drives

' 1V&, ; ..:_][

If this looks like a Lobo

Drive System, don't be

fooled. Just because it 2 SHUGART 801R

looks like one, works like POWER SUPPLY

one, smells like one, and tastes like one (?)

doesn't mean it has to cost like one!

TWIN VERTICAL DRIVES5" $550.00 - 8" $980.00

Attractive, convenient

and compact Two Drive

Mass Storage includes

Power Supply, Drives,

Cabinets and Cables.

Double Sided, Double

Track available tool $145.00 Kit (Less Cable)

Z-80 CPU (KIT)

The first time this

world popular CPU

offered in Kit. 2 serial,

3 parallel, CTC, EProm

Z-80 at 4 mhz. Software

buad rate, etc. {less Prom & cable)

$212.00

EXPANDABLE RAM

*SPECIAL*SPECIAL*SPECIAL*

This is the best allaround 64K boardyou can buy. If afteryou see it, you don'tagree return for fullrefund. Bank Selectby extended addresslines or I.O. 40H.

mm iti11iiit

'|Bi<i£!

* $389.00 A&T*

U$ - D$K $255.00

Double Density 8" and5" Disk Controllerdisigned for S-100 IEEEstandards. Uses WesternDigital 1795, 16912143 Chip Set.

FANS $14.95

$

These are brand new,

in the box fans. Not

noisey bearing pullouts.

Never again at these low prices]

3-1/8"

4-5/8'

4116s

Expansion 16K DynamicRAMs for Apple, TRS-80S-100 systems. T. I., MostekIntel, Call for manufacturer.

$2.95

200 NS

INTEL8251 $4.958255 $6.50

VERY POPULAR I.O. CHIPSBY LEADING MANUFACTURER

21148 A$3.25

One of the world's two

most popular STATIC

RAMs. Factory prime

tested units. Sold in lots of 8 only.

FUJITSU, HITACHI, etc.

200 NS

$4.25

250 NS

TMS-4044MM-5257INTEL 2147

CMOS Version $4.50!

The other of the world's most popular STATICRAMs. This one is 4K by 1 organization. Don'tbuy Gold, buy these, the price won't last!

2716s2708s

$7.50 (450 NS)$6.95 (450 NS)

Remember when 2716s were $50.00 and hardto get? These units are so beautiful it's hard topart with them. But we will, for a small price.Guaranteed!

SHUGART DRIVE8" 801R

$395.00

Manufacturer had

too many, buys at 8" 851 R $585.00

1000 piece rate,

sales dropped, so we got'em. Fantastic buy, get

them while they last! Full warranty.

SIEMANS DRIVE

8" 100-8 „,_,w>$375.00

Very Special Price on -»-»»wbww

these BRAND NEW current production unitsAdd $10.00 for Extended 1 Year Warrantee!

Circle 369 on inquiry card.

OAE's PP-Series EPROM Programmers plugdirectly into any vacant EPROM socket andallow you to transfer data directly from RAMto EPROMs. No additional power supplies arerequired. All timing & control sequences arehandled by the programmer. Each unit in-cludes internal DC to DC switching regulator,ZIF socket and 4 ft. ribbon cable terminatedwith a 24 pin plug. Programmers are availablefor all EPROMs from 2708's thru 2532's.

Oliver Advanced Engineering, Inc.

676 W. Wilson Ave.. Glendale, CA 91203

(213) 240-0080 or Telex 194773.

PP SERIES PROGRAMMERS

See us at NCC, booth 770

68000

ERG68-696 68000 CPUavailable and in produc-tion. Meets or exceeds allaspects of IEEE696 S-100standard.

$1995

Z-80 emulationteg rated 68000also available.

and in-

systems

Empirical Research Group, Inc.P0 Box 1176

Milton, WA 98354206-631-4855

WRITE YOUR OWNCOMPILERS IN PL/C

PL/C (Programming Language/Compilers) isthe implementation of a BNF superset as ahigh-level programming language.

Our Z80 version runs on a 32K CP/M™systemand generates TDL-format assembler code.

The PL/C Compiler, Runtime Library, andCompiler Source Code are shipped on anIBM-3740 format, CP/M compatible diskette.A license agreement must be completed.Lifetime single-CPU license fees are asfollows:

$1000 — PL/C Compiler, Runtime Library,Compiler PL/C Source, andPL/C Source Code for a PL/CCompiler Version which pro-duces PROCESSOR-INDEPEN-DENT macro source.

$5000 — As above, plus commented Assem-bler Source Code for the Compilerand Runtime Library.

A PL/C information package is available for $25

MRD Systems, Inc.

Box 147, Spring Valley, MN 55975

CP/M is a registered trademark of Digital Research

Circle 262 on inquiry card.

Circle 140 on Inquiry card.

Convert your TRS-80 into a

DEVELOPMENT SYSTEM

Z-80 In-Circuitemulation andEPROM/EEPROMprogramming ina single compactunit.

Debug stand-alone

systems with

program in

TRS-80 RAM,

then copy working program into PROM.

Only $329 including personality modulefor2716,2516,2758,2508,2532,2816,2808,48016.

ORION INSTRUMENTS

172 Otis Ave, Woodside, CA 94062(415)851-1172

Circle 271 on inquiry card.

RUN BIGCPM*

PROGRAMS

ON YOURMODEL 1 TRS-80*

WITH 39orS4Kof usespace.Can use MixedDrivers 5'A or 8" (Variable Tracks)Compatable with all TRS*80 OperatingSystems and all TRS*80 Programs.(usableon 48K disk systems only) Boards fit intokeyboard inclosure.

FREEDOM OPTION $245

MEMORY EXPANSION OPTION.... $295Send Check or Money Order to:

(MASS RESIDENTS. PLEASE INCLUDE SX TAX)

F-E.C. ltd.

P.O.Box 2388 • Woburn, MA. 01888

(017)944-5329 ;i!:^:^:::

wabash

When it comes to

Flexible Disks, nobody

does it better than

Wabash.

MasterCard, Visa Accepted.Call Free: (800)235-4137

PACIFICEXCHANGES

100 Foothill BlvdSan Luis Obispo. CA93401 (In Cal call(805)543-1037)

Circle 279 on Inquiry card.

r~ QUARTZ CRYSTALS **$

1 , .32188

52428 8

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3628B6-B

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4681288 , \

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All 8 -1159

OOHMflriF OF-HUCT 5" '

ADD SI.OO SHIPPING

CAL.

RES. ADD 6% SALES TAX

FREE OSCILLATOR SCHEMATICS

WITH ANY ORDER

1' QUALITY COMPUTER PARTS ! I

1 P.O.

BOX 743 / CHATSWORTH

, CA 91311 |

Agfa?Loaded

and Cassette Boxes

for

Software Producers& Duplicators

Ask lor our Catalog

POly 312/298-5300

1233 Rand Road • Des Plaines IL 60016

UPS ANYWHERE IN CONTINENTAL U.S.© UHF VABACTOB-TUNER. Channels 14-83,tunable. 1/0 = 75 ohms. Power Gain = 10-20 dB$23max. Complete with schematic and tech data.Brand new - surplus.

® NICAD 5 AA BATTERY PACK in shrink tube SCgswith solder tabs. Brand new - surplus O

© CABLE TV CONVERTER. For conversion to mid- Conor;band and superband cable stations. Brand new*04!'3and its LEGAL!

© BBAND NAME POWER SUPPLIES ±5V/6A. «mmHBVoltage adjustable and IC regulated. Ideal for'23CMOS, computer-based instruments, etc. use.Brand new - surplus

© MODULATOR. Video and sound input with 75 S-i egsohms output. Switchable to channels 3 or 4. IDShielded case. Brand new - surplus.SCR ELECTRONICS INC. [7141 527-25549533 VALLEY VIEW, CYPRESS, CA 90630Pay by CHECK, M.O., VISA, MIC, C.O.D.

Circle 304 on Inquiry card.

Circle 295 on Inquiry card.

Circle 324 on Inquiry card.

COMPUTER STOP

2545 W. 237 St. Torrance, CA. 90505

ORDER BY PHONE

MON.—SAT.

10-6

(213) 539-7670 PSTTELEX: 678401 TAB IRIN

LOWEST PRICES IN THE WEST.NORTH. SOUTH & EASTMcippUz computer 1-800-421-1947 A

^=^Kw Sales and Service ^ ^m

APPLE /// OPTION A: 3850 .^flH^k. ^ ^^^^

APPLE /// 96K

Information Analyst Package

12" B/W MonitorAPPLE///OPTION B: 4350

SAME AS OPTION A PLUS:

DISK II for APPLE///APPLE///OPTION C: 4800

SAME AS OPTION A PLUS:

DISK II FOR APPLE///

SILENTYPE Thermal Printer

APPLE HARDWARE

Parallel Printer Interface Card 160

Communications Card 195

High Speed Serial Interface 160

Pascal Language System 425

Centronics Printer Interface 185

Applesoft Firmware Card 160

Integer Firmware Card 160

Disk ][ with Controller DOS 3.3 529

Disk ][ only 475

Graphics Tablet 625

OTHER HARDWARE

Alf Music Synthesizer (3 Voice) 245

9 voice 175

ABT Numeric Keypad 119

Micromodem ][ 295

Apple Clock 245

Rom Plus with Keyboard Filter 175

lntrol/X-10 System 250

Romwriter 150

DoubleVlslon 80 x 24 Video Interface 245

CCS Arithmetic Processor 399

CCS Parallel Interface 119

16K Ram Card 145

Microworks DS-65 Digisector 339

SVA8inch Disk Controller 335

Sup-R-Mod 30

CCS Synchronous Serial Interface 119

CCS Asynchronous Serial Interface 99

Corvus 10 Meg. Hard Disk 4395

Corvus Constellation 595

MISCELLANEOUS/SUPPLIES

16K RAM (200-250 NS) 29

Verbatium Datalife Diskette (Box of 10) 30

Dysan Diskettes (Box of 5) 22

Apple Diskettes (Box of 10) 45

Verbatim Diskette Boxes (Holds 50 Disks) 18

Silentype Paper (Box of 10 rolls) 40

APPLE ][ Plus

16K $1075

48K $1193

Disk][Drive .. $529

with Controller & Dos. 3.3

PASCAL SYSTEM

$425

Z-80 Softcard

$299

MONITORS/DISPLAYS

Leedex Video 100 12" 140

Sanyo 9" Monitor 195

KG-12C Green Phos. Monitor 275

Sanyo 12" Green Phosphor. Monitor 275

NEC 12" Green Phosphor. Monitor 275

Sanyo 12" B/W Monitor 250

PRINTERS

Apple Silentype with Interface 525

IDS 445(Paper Tiger) with Graphics 650

IDS 460 with Graphics 1049

IDS 560 with Graphics 10) 1199

Centronics 737 795

NEC Spinwriter (RO, Serial) 2650

SOFTWARE

The Controller 525

Apple Post (Mailing List Program) 40

Easywriter Professional System 195

Apple Pie 2.0 95

DB Master Data Management 175

The Cashier 210

Apple Writer 65

Vlslcalc 170

CCA Data Management System 90

Full Screen Mapping for CCA DMS 59

Pascal Interactive Terminal Software (PITS) 29

Basic Interactive Terminal Software (BITS) 29

Data Capture 29

Data Factory DMS 110

Apple Plot 55

Apple Pilot 120

Magic Wand Word Processor (Needs Z-80 Softcard) 345

Dow Jones Portfolio Evaluator 45

Fortran 140

ORDERING INFORMATION: Phone orders invited using VISA, MASTERCARD or bank wire transfers. VISA & MC credit card service charge ot 2%.

Mail order may send charge card number (include expiration date), cashier's check, money order or personal check (allow 10 business days to clear.) Please include a telephonenumber with all orders. Foreign orders (excluding Military PO's) add 10% for shipping. All funds must be In U.S. dollars (letters of credit permitted). Shipping, Handling and in-surance in U.S. add 3% (minimum $4.00). California residents add 6% sales tax. Our low margins prohibit us to send COD or on purchase orders or open account (please send forwritten quotation). All equipment Is subject to price change and availability. Equipment is new and complete with the manufacturer warranty. We do not guarantee merchantibilityof products sold. All returned equipment is subject to a 15% restocking fee. We ship most orders within 2 days.

WE ARE A MEMBER OF THE CHAMBER OF COMMERCE. RETAIL STORE PRICES MAY DIFFER FROM MAIL ORDER PRICES.

PLEASE SEND ORDERS TO:

COMPUTER STOP, 2545 W. 237 St., TORRANCE, CA 90505

Circle 80 on inquiry card.

BYTE September 1981 465

Circle 238 on inquiry card.

>!„,,,,_

SI 00

2032 32K STATIC RAM A&T

450 NSEC...S579 00. 300 NSEC S585.00.200 NSEC...S629.00

2116 16K STATIC RAM A & T.

450 NSEC...S285.00.300 NSEC .5289.00.200 NSEC...S329.00

2065 64K DYNAMIC RAM A & T $548.95

2200 S-100 MAIN FRAM A&T S379.95

2<22 FLOPPY DISC WITH CP/M 2.2'" S329.95

2802 6502 PROCESSOR A&T S282.95

2610/1 Z80 CPU A& T $249.95

2710A4 SERIAL 1/0 A&T $291.95

2718* 2 SERIAL. 2 PARALLEL A&T $305.95

2720*4 PARALLEL A & T S214.95

PHOTO BOARDS WW . S39 95. SOLDERTAIL ..$29.95

APPLE PRODUCTS

7114A 12K ROM/PROM S68 50

7424A CALENDAR/CLOCK S106.95

7440A PROGRAMMABLE TIMER $98.50

7470A A TO 0 CONVERTER S105.95

7490A GPIB (IE 488) INTERFACE S265.95

7710AASYNC SERIAL S1 25.95

7712ASYNC SERIAL S153.95

7720A PARALLEL STANDARD S98.95

7720B PARALLEL CENTRONICS $98.95

7811 B ARITHMETIC PROCESSOR W/DISC S342.95

7811C ARITHMETIC PROCESSOR W/ROM S342.95

7500A WW BOARD $22.95

7510A SOLDERTAIt BOARD $23 95

SOFTWARE

2610 CP/NT MACRO ASSEMBLER ON DISK S76.95

2620 CP/M'" SYMBOLIC INSTRUCTION DEBUGGER ... S64.25

2630 CP/M'"TEXT FORMATER S64.25

2640 CP/M'" BACKGROUND PRINT UTILITY $42.95

OTHER CCS PRODUCTS ARE AVAILABLE.CALL FOR PRICE.

SStD

MICROCOMPUTER PRODUCTS

SI 00 PRODUCTSCBIA 8080 PROCESSOR PCBD....KIT S155.95, A&T

CB-2 280 PROCESSOR BOARDKIT $198.95, A& T

. $32.95$215.95

S269.95

VDIC 64 x 16 VIDEO. PCBD $32.95

KIT $153.95, A&T $199.95

VB2 64 x 16 VIDEO. PCBD $32.95

KIT $175.95, A&T $234.95

VB3 80 CHARACTER VIDEO 4MHZ

KIT $345.95, A&T $425.95

UPGRADE RAMS FOR VB-3

S42.00

104 2 PARALLEL. 2 SERIAL, PCBD $32.95

KIT S155.95. A&T $194.95

PB-1 2708, 2716 PROGRAMMER BOARD.

KIT S135.95. A&T $185.95

MB-10 16K STATIC RAM

KIT S299.95. A&T S339.95

APPLE PRODUCTS

A48B IEEE 488 INTERFACE $399.95

AID SERIAL/PARALLEL INTERFACE

KIT S125.95, A&T S155.95

ASIO SERIAL I/O

KIT S87.95. A&T $97.95

APIO PARALLEL 10

KIT(W/0 CABLES) $67 95, A&T(W/0 CABLES) S87.95

OTHER SSM PRODUCTS ARE AVAILABLE.CALL FOR PRICES.

MONDAY-FRIDAY, 8:00 TO 12:00, 1:00 TO 5:30THURSDAYS. 6:00 TO 9:00 P.M

(415) 728-9121P.O. BOX 955 • EL GRANADA, CA 9401 8

PLEASE SEND FOR IC, XISTOR AND COMPUTER PARTS LIST

SEPT. SPECIAL SALEON PREPAID ORDERS

ICHARGE CARDS AND COD ORPO NOT AVAILABLE ON THESE OFFERS]

WAMECO BOARDS WITH MIKOS PARTS 10% OFFADVERTISED PRICE

W777C

inc. WAMECO INC.

BOARDS WITH MIKOS PARTS

MEM-3 32K STATIC RAM. PCBD $36.95

KIT LESS RAM $95 95, A&T $135.95

CPU-2 Z80 PROCESSOR, PCBD $32.95

KIT LESS ROM $109.95, A&T $149,95

EPM-2 16K/32K EPROM. PCBD $32.95

KIT LESS ROM $65.95, A&T $99.95

FPB-1 FRONT PANEL. PCBD $48.50

KIT $144.95, A&T $184 95

CPU-1 8080 PROCESSOR, PCBD $29,95

KIT $89.95, AS T $129.95

QMB-12 13 SLOT MOTHER BOARD. PCBD $39.95

KIT S95.95, A&T $135.95

OTHER WAMECO PRODUCTS ARE AVAILABLE.CALL FOR PRICES.

MIKOS PARIS ASSORTMENTS ARE ALL FACTORY MARKED PARTS KITS INCLUDEALL PARTS LISTED AS REQUIRED FOR THE COMPLETE KIT LESS PARTS LISTEDALL SOCKETS INCLUDED

LARGE SELECTION OF LS TTL AVAILABLE.

PURCHASE $50.00 WORTH OF LS TTL AND GET 10% CREDITTOWARD ADDITIONAL PURCHASES. PREPAID ORDERS ONLY.

VISA or MASTERCHARGE Send account number, interbank number, expiration daleand sign your order Approx postage will be added Check or money order will be sentposl paid in u S II yon are not a regular customer, please use charge, cashier's check orpostal money order Otherwise there will be a two-week delay lor checks to clear Califresidents add 6"b tax Money back 30-day guarantee We cannot accept returned IC'sthat have been soldered to Prices subject tc change without notice S10 mliiiruim order.SI.50 service charge on order! leu thin s10.00.

STOP

LOOK LISTEN

DON'T TURN THIS PAGE. .. AT THESE POPULAR.

. . .if you are tired of dealing with mailorder houses that never have in stockwhat you need, when you need it. Weare not a mail order house. MicroSource of Texas is a stocking wholesaledistributor of microcomputer printers,video display terminals, and supplies.What makes us different? We don't justtake orders!

Whether you're a dealer, systemsintegrator or first-time micro user,you expect help from your supplier indetermining the best product to fit aparticular application. We give thathelp, and more. Since complete doc-umentation is essential, we provideit with every order we ship. And ifyou're located in Texas, stop by andwe'll demonstrate our products withoutobligation. Try to do that mail order!

Don't waste valuable time. Talk toMicro Source. We can help.

. . .low cost, high quality products:

• EPSON MX-80 matrix printer

• C.ITOH "Starwriter" WP printer

• TELEVIDEO Model 910 CRT terminaland many more!

What about supplies? No hassle.We stock ribbons and accessories forEPSON, C.ITOH, DIABLO, QUME,NEC, DEC, and CENTRONICS printers.All products and supplies are in stock,available for immediate delivery.

Micro Source of Texas is a specialtydistributor handling only peripheralhardware. We don't sell microcom-puters or software. So if you're asystems dealer, consider us a depend-able supplier, not a competitor.

Micro Source wants to be yoursource.

Micro Source of Texas, Inc.

834 N Glenville DriveRichardson. Texas 75081

214-690-5111

TO WHAT WE OFFER. . .

LOW PRICES

The best in the industry! Because ofour volume purchases, we offer at-tractive discounts to independent deal-ers and micro systems builders. Callor circle our reader inquiry number andreceive a current dealer price list andcatalog.

IMMEDIATE DELIVERY

We stock a variety of popular microprinters and display terminals includ-ing EPSON, C.ITOH. and TELEVIDEO.If your needs are immediate, we'll shipwithin 24 hours of receiving your order.And if you're nearby, just drop in andpick up your order the same day.

TECHNICAL ASSISTANCE

Micro Source offers in-depth appli-cation assistance to Apple, Commodore,and TRS-80 dealers, among others. Wewant you to buy the right product withthe right interface at the right price.Product support and courteous serviceare "standard features'' with MicroSource. Call today and make us prove it!

WE'RE IN TEXAS

Ask about our NO FREIGHT

CHARGE special offer to

Texas customers

466 BYTE September 1981

Circle 226 on inquiry card.

DOWN-TO-EARTH PRICES ON

OUT-OF-THIS-WORLD PERSONAL

COMPUTERS AND COMPONENTS.

Look at these easy hardware prices:

Look at this!

Ohio ScientificSuperboard II

$329

• It's the first complete computersystem on a board.

• Superboard II uses the ultrapowerful 6502 Microprocessor

• 8K Microsoft BASIC-in-ROM

• 4K static RAM on board,expandable to 8K

• Full 53-key keyboard, with upperand lower case. Plus userexpandability.

• Video interface and audiocassette interface.

The Ohio Scientific Superboard II at$329 — in today's economy — hasgot to be the best buy by far. It willentertain you with spectaculargraphics made possible by its ultrahigh resolution graphics and superfast BASIC. It will help you in schoolor industry, as an ultra powerfulscientific calculator. Advancedscientific functions and a built-in"immediate" mode allow you tosolve complex problems withoutprogramming.

The Superboard II can beexpanded economically, for businessuses, or to remotely control yourhome appliances and security. Evencommunicate with other computers.

Read what's been writtenabout Superboard II:

"We heartily recommend Super-board II for the beginner who wantsto get into microcomputers with aminimum cost. A real computerwith full expandability."

—POPULAR ELECTRONICS, MARCH 1 979

"The Superboard II is an excellentchoice for the personal computerenthusiast on a budget."

—BYTE, MAY 1979

610 Board For use with Superboard II and Challenger 1 P.

8K static RAM. Expandable to 24K or 32K system total.

Accepts up to two mini-floppy disk drives. Requires +5V

@4.5 amps. S 298

Mini-Floppy Disk Drive Includes Ohio Scientific's PICO DOS

software and connector cable. Compatible with 610

expander board. Requires + 1 2V @1.5 amps and + 5V @

0.7 amps. [Power supply S. cabinet not included.] 299

630 Board Contact us for important details. 229

AC-3P 12" combination black and white TV/video monitor. 159

4KP 4K RAM chip set. 79

PS-005 5V 4.5 amp power supply for Superboard II. 45

PS-003 12V power supply for mini-floppies. 45

RF Modulator Battery powered UHF Unit. 35

AC-12P Wireless remote control system. Includes controlconsole, two lamp modules and two appliance modules, foruse with 630 board. 175

AC-17P Home security system. Includes console, fire

detector, window protection devices and door unit for use

with 630 board. 249

C1P Sams C1 P Service manual 8

C4P Sams C4P Service manual 16

C3 Sams Challenger III manual 40

Ohio Scientific and independent suppliers offer hundreds of programs for theSuperboard II, in cassette and mini-floppy form.

Freight Policies All orders of $100 or more are

shipped freight prepaid. Orders of less than $100 please add$4.00 to cover shipping costs. Ohio residents add 5.5% Sales Tax.

■

Hours: Call Monday thru Friday.B:OD AM to 5:00 PM E.D.T.TOLL FREE: 1-800-321-5805

Guaranteed Shipment

Cleveland Consumer Computers & Componentsguarantees shipment of computer systemswithin 48 hours upon receipt of your order.Our failure to ship within 48 hoursentitles you to 835 of software, FREE.

ilIII

I

:

I

To Order: Or to get our free catalog CALL 1-800-321-5805 TOLL FREE. Charge yourorder to your VISA or MASTER CHARGE account. Ohio residents call: [216] 464-8047.Or write, including your check or money order, to the address listed below.

CLEVELAND CONSUMERCOMPUTERS & COMPONENTS

P.O. Box 46627Cleveland, Ohio 44146

I ■■ Ml ■■■■■■■■^H ■■■■§■■ Mi HUM ■■■■■■ l

flnrlan Cnn rwi ■ CLEVELAND CONSUMER P.O. Box 46827

UlUCr rUI III. COMPUTERS & COMPONENTS Cleveland, Ohio 44146

D Superboard II £329. □ RF Modulator £35.

□ 610 Board $298. □ AC-3P 1 2 " BAA/ Monitor £1 59.

□ Mini-Floppy Disk Drive $299. □ C1P Sams Manual $8.[Attach separate sheet for other items.]

NAME

ADDRESS:

CITY:PHONE:

STATE:

ZIP:

Payment by: VISA

MASTER CHARGE

MONEY ORDER

Credit Card Account #

Expires.

. Interbank #[Master Charge]

TOTAL CHARGED OR ENCLOSED £_

. [Ohio Residents add 6.5% Sales Tax]

Orders of less than SI 00, please add $4.00 to cover shipping costs. Orders will be accepted from U.S. andCanada only. All prices quoted are U.S., date of publication, standard UPS shipping FOB the factory.PRICES SUBJECT TO CHANGE WITHOUT NOTICE

Circle 62 on inquiry card.

BYTE September 1981 467

COMPUTERS

ATARI" 800™COMPUTER SYSTEM

16k-*750.0048k-*898.00

APPLE II Plus"

4S*-*119

64/c-*13S

kgs

74S00

74SOO74S0274S0374S0474S0574S1074S1574S2074S2274 53074S3774S5074S5174S6474S7474S8674S11274S132

74S13874S14074S15874S17474517574S18274S18974S20174S24074524474S25174S28774528874S29974S47074S47174S47374S474

COMPONENTS CONT'D

{video

too

MONITORS

video

mo

1121.

|12mhiI BLACKS WHITEIVIDEO MONITOR|AMMK iLEEDEXjCorp.

12MHz AMDEK'

GREEN PhosVIOEO MONITOR

*365°°

1971 SO. STATE COLLEGEANAHEIM, CALIF. 92806

*10.MIN ORDER/CA. RES. ADD 6°/<FRT . . .

5N740ON5N7402NSN7404NSN7408NSN7410NSN7412NSN7413NSN7414NSN7416NSN7417NSN7420NSN7425NSN7430NSN7437N5N7438NSN7440N5N7442NSN7443NSN744SNSN7451NSN7454NSN7474NSN7475N

SM7482N

SN74»2N

SN7493N

SN7405N

SN7490N

SN74122N

SN74136N

SN74141N

SN74151N

SN74153N

SN741S4N

SN74155N

SN74157N

SN74160N

SN74161N

SN74163N

SN74164N

SN74165N

SN74174N

SN74175N

SN741BON

SN7410IN

SN74393N

74LS00

74LSOO74LS0274LS0374LS0474LS0574LS0674LSOS74LS1074LS1474LS20MLS2174LS2074LS2774L52874LS3074LS3274LS3874 L 54274LS4874LS7474LS7574LSB674LS0074L593

MLsee

74LS10774LS11374LSI2274 LSI2374LS12574LS126. 74LSI3874 LSI 3974LS15174 LSI5374LS157

74LSI50

74LSW1

74L5162

74LS163

74LST64

74 LS165

74 LSWS

74 LSI 70

74 LSI74

74LS175

74LS10O

74LS191

74LS196

74 LS1Q7

74 LS221

74LS240

74 LS241

74 LS243

74 LS244

74 LS245

74 LS251

74LS253

74LS257

MLS259

74L5260

74 LS273

74LS279

74LS200

74 LS203

74LS365

74 LS3*7

74LS373

74LS3W

74LS377

74LSM0

74LS670

EPROMS2716 6.95 ea

5V 450MSTMS27162708 8 25ea

450NS 4.10 m

8 lot 6.2503

8 tor 7 50ea8 (Of 3.95ea

2732 I9.96ea 4 tor 16.95*a

4116 300MS 2 00ea 8 (or 14 00200NS 235«a 8 (or 16.00

2114L 3O0NS 29Sea4tor 2.75*a200NS 3.50ea 4fOf 3.00ea

2111 450NS 250ea»for 2 OOea

CPUs2 80

Z 6GA CTCZ BOA CPUZ 80 002 16-64K

2901AMC6800

MISC.2102

450NS8038NE555AYS 1013 A148814898T26BT2882128216

IS410SCRIT410TT11AC790579067915791B780578067BOB7812

MC1330A1PMC1350PMC1358PLM380LMS65NLM741MC1458PLM720LM386

1981

I.C. MASTER* 59.95

7.9510.5010 50129.0013.507.509.50

1103AUPD765(loppy diskcontrol lotULN20O1TMS4400MC4008PMH0026D3624D3O01D3002

85 IC SOCKETS.85 8 PIN 10/1.20

14

10/ 1.40

16

10/1.60

18

10/1.90

20

10/2.80

22

10/2.80

24

10/2.80

28

10/3.80

55

40

10/4 75

TERMINALS

*68ft00

Synertek"KTM-3"

LOW COSTTERMINAL WITHKEYBOARD ANDVIOEO 100 „* <499.00 *

** SPECIALS**

3it*« MUFFIN FAN »/i,n. <»«!•9 96

UPD 765C Floppy Olak Controls

•17.96 »;w«'.2732A: »0nsec. EPRO*

•24.50AY5-1013A:3WbM UAST •!»

REAL-TIME CLOCKCALENDAR (MSM5832)

DtttflftM. Mono Matal Cut. CMOS I C

faUltl

Tana, Month. Data,\»jar. 1

'Oavotwaak

■BlMOrlontod

■t Bit Data Sua

-4 Bit Addr.is

■"/WHoMSflK.

■Intar. Signal XTAL

■32 768Ktw xtal Control *3-85

' 5v Row Sup

'Low Powat Dlaatpation

*7.45

l/SKd

GLOBAL

Logic Probes

LP_1: *40.oo

Pui«« width ioratMtOlOrn'ru

LP-3: *6a00

Pulse width to6TMC R*D toov.l 6OMH1

OR

SHELF/ DESKMOUNTED*5722

$155°°

DESC-

II W CHMtllli IIEI11I HUt

III HiKKWill tint* Mill

Kiwiii muam/ nmm:< fin in wicid m i iiHi

POWER,(SUPPLY

MODEL*CP198

input—I107l25v

output —5vdc

u 6amps'.29.95

Apple Expansion Kit

16K Memory Add-On

Includes Instructions

$25 95

TRS8O

16K Add-On

Instructions*

Dip Switches

$25.95

LPK-1:

LoflK ProbeKit-comptote

nothing oitrato buy Mm.pulse widthUOnaK-

*ia95_

CARDS

MICROSOFTZ80.

$295°°16K RAM

$16000

VIDCX

VIDEOTERM

BO column

*295°oKEYBOARDENHANCER

*120°°

CALIF COMPSVS

APPLECLOCK*12400

PROTOBOARD*25°°

PRINTERS

EPSON

MX-80

*5600o

CENTRONICS

737-1

*950°°

753-1

*2.995P°

BASE II. inc

8006

*649°° I850

*749°°

FLOPPY DISK DRIVES

Qume Datatrak-8 $540

Virtually the industry standard. High quality/reliabil-ity. Full featured, double-sided, double density.

SA851 $540

Full featured drive, double sided, double density

SA801R $395

Single sided, double density, very consistent

FDD100-8 $395

Qume Datatrak 5 5%" $345

SA-400 5%" $299

Tandon TM-100-2 S%" $350

We are expecting a large shipment of mini's, many types. Call for details.

CONTROLLERS

Tarbell single density kit $195 -'A8*

Tarbell single density A&T $310 S^S^SS'

Tarbell double density A & T $425 3* *J||«s

CCS 2422 w/CPM 2.2 $350 ||§i| ^m~

Godbout Disk 1 $450

MDA MXV-21 LSI-11 controller $1050

(RX-01, RX-02 compatible)

MISCELLANEOUS

CCS Mainframe $395

2 Disk drive enclosure $ 95

(fits Siemens, Shugart, Qume)CP-206 power supply $110

(powers two floppies)

Cable Kits 2 drives $ 35

3 drives $ 40

4 drives $ 45

Diskettes ss $39/10 - ds $59/10

CPU

CCS 2810 $ 275

Godbout Z-80A $ 275

Godbout 8085A $ 295

MEMORY

CCS 2065 64K dynamic $ 625

CCS 2116 32K static $ 675

Godbout RAM 17 64K $1250

I/O

CCS 2710 4 SIO $ 325

Godbout Interfacer 1 $ 225

Godbout Interfacer 2 $ 225

Qume S/5 — Daisy Wheel Printer

Sprint 5/45 RO $2699

Sprint 5/55 RO 2829

Sprint 5/45 KSR 3029

Sprint 5/55 KSR 3159

Forms Tractor 210

Pinfeed platen 155

Paper Guide 30

Paper Basket 50

many print wheels, ribbons, & more available.

Terms of sale: cash or checks, purchase orders from qualified firms and institutions. Minimum order $25. CA residents add 6% tax. Pricessubject to change without notice. All goods subject to prior sale. Minumum shipping/handling charge $4.00.

Electrolabs

POB 4436, Stanford, CA 94305 (415) 321-5601

Circle 132 on inquiry card.

INCREDIBLE? believe

Qantex 6000

PRINTERS

150 cps bidirectional-9x9 dot matrix, quietizedcase, 136 col, vertical form control and manyother functions SHQR

We feel this printer offers * I 133

the best price/performance ratio available.RS-232 serial to 19,200 baud x-on, x-off add $40

rjT^ Teletype 40, 300 LPM-typewriter quality, RS- from Only

232 interlace. This quality printer is available in many $2928configurations including forms access, quietized case, etc.Teletype 43 from $995Teletype AP-200, 340 cps dot matrix (similar to Data Prod. M-200) S2799NEC Spinwriter-55 cps, bidirectional, letter quality

R.O. S2660 KSR $2942

DIABLO 630-40 cps, bidirectional, daisy wheel, plot/graph $2449

C. ITOH Starwriter, 25 cps, daisy wheel $1575

C. ITOH Starwriter. 45 cps, daisy wheel $1849

EPSON MX-80, 80 cps, 9x9 dot matrix SCALL

ANADEX 9500/9501, up to 200 cps, high resolution dot $1349

OKIDATA Microline 80, 80 cps, 9x7 dot matrix $490

Microline 82, bidirectional, friction/pin feed $599

Microline 83, bidirectional, 120 cps, uses 15" paper $875

TI-810,150 cps, Basic $1695

Package-Compressed print, vertical form control $1830

CENTRONICS 704-9,180 cps, 9x9 dot matrix, 132 col, RS-232 $1595

704-11,180 cps, 9x9 dot matrix, 132 col, parallel $1695

730,100 cps, 7x7 dot matrix, same as RS. LPII $660

737.80 cps, nx9 dot matrix, same as R.S. LPIV $849

739 Graphics SCALL

DECLA-34 $1085

IDS460G $1199

S-100 SPECIALTIES

DP1Z-80A, CPU, 64K ram, floppycont., RS-232 port, SI00 IEEE, 8 slotin adds terminal, inc. CP1M2.2 SCALLDelta has Winchester based networks of up to 16 users available.

ES2S3Croup Ca" us ,or best pnces on these hign Qua||,y

generation boards and systems.|P California These high quality, reliable products have made CCS|^" Computer defacto industry standard for S-100 products■I Systems Assembled and tested: list only

2200 H.D. Mainframe, 20 a. P.S., 12 slot MB $434 $359

2065C 64K dynamic RAM/Bank Select $720 $580

2810A Z-80 CPU, serial port, ROM monitor $310 $259

2422A Floppy Cont, CP/M 2.2, ROM monitor $425 $345

, 8000 DT — w/164k. 1.2 MB8" floppies, 2 serial, 3 par. CPM 2.2 $CALLFULL 2 YEAR WARRANTY!

Z-80 CPU $310

D2 Disk controller $354

64K Dynamic Ram $648

/HICROBYTE FULL SYSTEMS AVAILABLE

SUPERBRAIN Scall

Similar savings on the full lines of CCS, SSM, NNC, MORROW, DELTA,NORTHSTAR, ITHACA INTERSYSTEMS, GODBOUT, NEC. TELEVIDEO, IMSZENITH, ADDS, DEC, DATA GEN., ATARI, DYNABYTE.

®.®

$450

$625 2 fo

r$1199

$299

$445

$963

$1259

List

only

$5350

Scall

$6450

Scall

$750

Scall

$790

Scall

$4995

$3995

$1500

$1275

$6995

$5995

$5995

$5099

8" DISK DRIVE SALE

8"SHUGARTSA801RQUME DATATRACK 8

Enclosure, power supply for 2 8" drives A&TNNC industrial grade enclosure for 2 drives with PS.MORROW Discus 2D + CP/M®Discus 2 +2 +CP/M®

HARD DISK SPECIALS

C0RVUS 10MB and controller20MB and controllerConstellation Network MultiplexerMirror Video Tape Disk BackupMORROW 26MB + controller + CP/M 2.2®CAMEO cartridge drive controller

, controller, CDC Hawk Drive (5 fix, 5 rem)controller, Western Dynex (5 fix, 5 rem)d^ Winchester 5Vi drives complete with case, cable

£llv software, S-100 controller. Adapter avail, for use with

^pXCOMP any Z -80 system. Cartridge drive controllers avail Ljst

5MB $2898

10MB $3398

Quantity discounts available!

|r.v-r-i| S"100 CONTROLLER FOR PRIAM $693

I1* ' 1 PRIAM 8" and 14" Winchester/tape subsystems avail.We carry the full line of ADES disk and tape controllers and subsystems.

FULLY CONFIGURED BUSINESS SYSTEMS

The following are some examples of the fully assembled and tested business

and scientific computer systems which we offer. All include CP/M 2.2,

64K bytes dynamic RAM, Z-80A 4mh CPU. We offer a full line of quality,

tested software.

Delta TVD w/1.2 Mb floppy drives, 2 serial, 3 parallel ports $CALL

Delta 1004 w/10 MB hand disk, 1MB floppy, 6 serial, 3 parallel ports SCALL

CCS 2210A w/floppy controller, 1 serial port $1849

CCS 300-1A w/1.2MB floppy drives, 2 serial, 2 parallel ports $4849

CCS 400-1A w/10MB hard disc, 2 serial, 2 parallel ports $6999

Optional CP/M for CCS 300, 400 (OASIS available) $150

NNC 80 w/1 MB floppy drives, 2 serial, 3 parallel ports $3799

NNC 80W W/.5MB floppy, 8.4MB hard disc, (OASIS optional) $6693

ALTOS single and multi-user systems Scall

MORROW Decision 1, MICROSOFT basic, UNIX Scall

TERMINALS

AMPEX DIALOGUE30, 80

TELEVIDEO 912 C $950

920C $1030

950CSOROC10120IQ 140

INTERTUBE III or EMULATOR (multi-terminal)

DECVT-100

Similar savings for our HAZELTINE and LEAR SIEGLER lines

LOOK HERE! aivipex

Call us for ALL your softwear needs Dialogue 80

SYSTEMS HOUSES & EDUCATIONAL INSTITUTIONSGIVEN SPECIAL CONSIDERATION.

$1195$995

$1395S895

$2050

SCALL$725$789S989$729

$1149$799

$1575

ALL OF OUR PERIPHERALS CAN BE CONFIGURED FOR RADIO SHACK" MODEL I

DEALER and INTERNATIONAL INQUIRIES WELCOME

WASHINGTON COMPUTER SERVICES

anaffiliateof (((WASHINGTON))) est. 1912wE6ECTRtC COflftPdNY '"

CUSTOM COMPUTER ROOM WIRING SINCE 1960

97 Spring Street

New York, N.Y. 10012

Hours: 8AM-5:30PM (EST) Mori.-Fri.

Circle 381 on inquiry card.

TO ORDER: CALL OUR TOLL-FREE NUMBER:• (800) 221-5416* In N.Y. State and fortechnical information call 1(212) 226-2121

For fast delivery, send certified checks, money order orcall to arrange direct bank wire transfers. Personal orcompany checks require two to three weeks to clear. Allprices are mail order only. Prices subject to changewithout notice; call for latest prices. Prices include 2%cash discount. N.Y. residents add sales tax.Quantex is a trademark of North Atlantic Industries, Inc.Radio Shack* is a trademark of the Tandy Corp.CP/M® is a trademark of Digital Research

BYTE September 1981 469

Circle 283 on inquiry card.

SAVEUP TO $600.00 NOWon TRS-80 Computers & Accessories

With This Coupon

Now you can own a great little computer at a great big dicount off the manufacturer'slist price. For home or office use the Radio Shack line of computers is first in quality,performance and price.

• FREE SHIPPING in the 48 continental contigious states. Model

• NO SALES TAX collected on out-of-state orders.

• CONVENIENT ORDERING Call us TOLL FREE.

• FREE COMPLETE PRICE LIST available upon request.

Catalog Charge

Number Description List Price By Phone

Radio Shack® TRS-80 Model II

26-4002 64K 1-Disk Model II 3,899.00 3,579.30

Radio Shack® TRS-80 Model III

26-1062 Model III 16K 999.00 865.00

26-1066 Model III 48K 2,495.00 2,243.50

Radio Shack® TRS-80 Color Computer

26-3001 4K Color Computer 399.00 359.10

26-3002 16K Color Computer 599.00 539.10

Atari® CX-2600 Video Computer System 180.00 164.95

Pioneer® VP-1000 LaserDisc Player CALL FOR PRICES

Mattel Electronics® Intellivision" Home Video System CALL FOR PRICES

Magnavox® Odyssey2Home Video System CALL FOR PRICES

Magnavox® Magnavision® Videodisc Player CALL FOR PRICES

J Cashier'sCheck OrMoney Order

*3,299.00

865.00*2,149.00

359.10539.10164.95

Cash PriceYou Save

600.00

134.00346.00

39.9059.0015.05

Pan AmericanElectronics

CALL TOLL FREE

800-531-7466'Dept. 19

(Operator 19) • Texas & Principal Number 512/581-27661117 Conway Avenue • Mission, Texas 78572NEW BRANCH2912 N. Main. Fort Worth. Texas 76106 » Phone Number 817-625-6333 » Telex 794836

Telex 767339

TRS-80 is a Trademark of Tandy Corp. 'With this coupon only! Prices subject to change without notice.

SUNNY LOW LOW COST

POWER.SUPPLIES

FOR S-100, FLOPPY DISKS.

KIT 1, 2 & 3 For S-100

R3

For Three 8" or5W Disk Drives

S-100 POWER SUPPLY KITS (open frame with base plate, 3 hrs. assy, time)

ITFM

USED FOR

@ - 9 Vdc

@ + 16 Vdc

@ + 28 Vdc

SIZE W x D x H

S3 2 in 1 Unit for S-100 andtwo 8" or 5Vi" Disk Drives. It fitsmost Disk System Mainframes.

PRICE

KIT 1 15 CARDS SOURCE 15A

KIT 2 SYSTEM SOURCE 25A

KIT 3 DISK SYSTEM 15A

1A

2.5A3A2A

25A3A2A

4A

12"12"14"

4V4'/a"4'/s"

52.9559.9567.95

DISK DRIVE POWER SUPPLY "R3" regulated, open frame, assy. & tested 67.95

SPECS + 5V @ 5A OVP. -5V @ 1A + 24V@ 5A. SHORTS PROTECT 2 SIZES AVAIL ,1)9" (W) x 6V„" (D) x AH" (H). 2) 9" (W) x Ah" (D) x 5Vt" (H)

OPTION 1 ) REPLACE + 24V BY + 12V. 2 ) FOR SIZE 1 ONLY. ADD + 12V @ 1A. AT AN ADDITIONAL $12 00

IDEAL FOR THREE 8" or 5'A FLOPPY DISK DRIVES. SUCH AS SHUGART 801/851. SIEMANS FDD 100-8/200-8 OR 100-5 ETC

DISK SYSTEM PWR SUPPLY "S3" open frame, assy. & tested, compact size: io"(w) * 6- p) >. 5" <hj 92.95

REGULATED OUTPUTS FOR DISK DRIVES -t 5V @ 4A. 5V @ 1A. +24V @ 4A (OR + 12V @ 4A) SHORTS PROTECT

UNREGULATED OUTPUTS FOR S-100- +8V @ 14A. ± 16V @ 3A (OPTION ADD OVP FOR +5V. ADD $5 00)

A COMPLETE UNIT FOR DISK SYSTEM WITH THE MAINFRAME CONTAINING 12 SLOTS & TWO 8" or 5V." DISK DRIVES

POWER TRANSFORMERS (with mounting brackets)

ITEM PRIMARY SECONDARY #1 SECONDARY #2 SECONDARY #3 SIZE W x D x H PRICE

T1T2T3

T4T5

110/120110/120110/120110/120110/120

8 Vac, 15A8 Vac, 25A8 Vac, 15A8 Vac, 6A8 Vac. 6A

28 Vac, CT, 2.5A28 Vac, CT, 3.5A28 Vac, CT. 2.5A28 Vac. CT. 1.5A28 Vac. CT. 2A

48 Vac, CT, 2A48 Vac, CT, 3A

33/i"

33/4"

3"

x 35/s" x 3VB"x AH" x 3V8"x AH" x 3Vs"x 35/s" x 3Vs"x 3" x 2W

21.9527.9529.9522.9514.95

SHIPPING For each power supply $5.50 inCalif., $7.50 in other states, $14.00 in CanadaFor each Transformer $5.00 in all States.$10.00 in Canada. Calif. Residents add 6%Sales Tax.

MAILING ADDRESS:P.O. BOX 4296TORRANCE, CA 90510

TELEX: 830-5010

ANSWER BACK FOR TELEX SUNYCO TRUC

SUNNY INTERNATIONAL

(TRANSFORMERS MANUFACTURER)(213) 328-2425 MON-SAT 9-6

SHIPPING ADDRESS:22129V2 S. VERMONT AVETORRANCE, CA 90502

470 BYTE September 1981

Circle 340 on inquiry card.

Better Products,

■ .zVT 1.1'V- T* ■

JADE

Double-D ™

Get the Inside Track

I

r^^Ifc* ****** u>

I

S-100 bus compatible • Reads and writes singleor double density • Density is software selectable• Controls up to four 5-1/4" or 8", single or double-sided drives "Singleor double-sided drives may bemixed in the same system • On-board Z-80A toassure reliable operation • EIA level serial printerinterface on board, baud rates to 9600 (perfect fordespooling operations) • Uses IBM standardformats • Designed to meet IEEE signaldisciplines • Works with 8080, 8085, and Z-80CPU's.

IOD-1200B Bare Board $59.95

IOD-1200K Kit $299.95

IOD-1200A A&T $375.00

SFC-58001200E DD boot PROM .... $20.00SFC-59002001F CP/M2.2forDD . $149.95

JADE

Memory Bank ™

8 or 16 Bit Dynamic Memory

A 64K S-100 dynamic memory that looks towardthe future. • S-100 standard pinout and signaldiscipline • 8 or 16 bit words, automatically,depending on the type of CPU on the bus • 4-layerPC board designed for extremely low-noiseoperation.

With its on-board refresh controller, this boardallows DMA operations without regard to timefactors. It will'run reliably at any system clockrate up to 4 MHz-because it is clocked with thesystem clock itself (no one-shots are used fortiming operations). Its unique design enables it toswitch from a 64K by 8-bit board to a 32K by 16-bitboard automatically (responds to IEEE's 16 Rqstline and, if enabled, replies with 16 Grant).

MEM-99730B Bare Board $49.95

MEM-99730K Kit, no RAM $i99.95

MEM-16730K 16K kit $219.95

MEM-32731K 32K kit $239.95

MEM-48732K 48K kit $259.95

MEM-64733K 64K kit $279.95

Assembled & Tested add $50.00

4 MHz Z-80 CPU, 80 x 25 display with graphics and 8colors, 32K RAM, 24K ROM, parallel/serial/cassetteinterfaces, upper/lower case, numeric keypad, 10 specialfunction keys, uses CP/M 2.2.

NEC-8001A 32K CPU/keyboard .. $1095.00NEC-8012A I/O with 32K RAM ... $695.00

NEC-8031A Dual disk unit $1095.00

VDM-651200 12" green CRT $269.95

NEC-1202D Hi-res RGB color CRT $1045.00NEC-90005 Gen. accting softwr ... $375.00

JADE

The Big Z

Z-80A Based CPU

TM

S-100 bus compatible • Switch selectable 2 or 4MHz operation • Serial I/O port • Accomodates a2708, 2716, or 2732 EPROM in shadow modeallowing full use of 64K RAM • MWRITE signal isgenerated automatically if used without frontpanel • On-board 8251 USART controls serial portat baud rates from 75 to 9600 baud • Switchselectable IK, 2K, or 4K boundary fully buffered •Power-on jump to EPROM

CPU-30201K Kit $139.95

CPU-30201A A&T $189.95

CPU-30200B Bare board $35.00

Memory Chips on Sale

21111

. 1 MHz

3.35

2.99

2.75

2.49

2708

2 MHz

4.90

3.90

3.45

2.90

2532

2 MHz

24.90

19.90

15.90

12.90

2716

2 MHz

8.90

7.45

6.45

5.75

2716

■1 MHz

19.90

15.45

13.45

11.75

2732

2 MHz

24.90

19.90

15.90

12.90

2732

■1 MHz

39.90

29.90

24.90

19.90

2758

2 MHz

6.90

6.25

5.50

4.50

4116

201) MS

3.25

2.99

2.49

1.99

1164

200 ns

28.90

24.90

22.90

19.90

JADE

Disk Sub-Systems

Shugart, Siemens, Qume

Handsome metal cabinet with proportionallybalanced air flow system • Rugged dual drivepower supply • Power cable kit • Power switch,line cord, fuse holder, cooling fan • Never-Marrubber feet • All necessary hardware to mount 2-8" disk drives, power supply, and fan • Does notinclude signal cable

Dual 8" Subassembly Cabinet

END-000420 Bare cabinet $59.95

END-000421 Cabinet kit $225.00

END-000431 A&T $359.95

8" Disk Drive SubsystemsSingle Sided, Double DensityEND-000423 Kit w/2 FDlOOSDs .. $975.00END-000424 A & T w 2 FDlOO-HDs $1175.00END-000433 Kit w/2 SA-SOIRs .. . $999.95END-000434 A & T w/2 SA-801Rs $1195.00

8" Disk Drive SubsystemsDouble Sided, Double Density

END-000426 Kit w 2 DT-Hs $1475.00

END-000427 A & T w/2 DT-tis ... $1675.00END-000436 Kit w/2 SA-851Rs .. $1495.00END-000437 A&T w/2 SA-851Rs $1695.00Circle 178 on Inquiry card.

JADE

S.P.I.C.

Our

"SPICy"

New I/O Board

.„..'. ;_,. '■■'■ -. Ti-wWt ''■■■■ ;'t?~'7,7wi; ■

I 1 -'

■K-^;-#-JB^^r=rrL-^-~-..~.rv.v---^;

Sk!

17)i",. ~ jj

■""■ jmnrnmnnmi

IHIMIHJUH

New, from JADE, one of the most advanced,technologically sophisticated Serial/ParallelInterrupt Controller systems in the world. On asingle IEEE S-100 standard board, JADE haspacked two bi-directional parallel ports with fullhandshaking, four serial channels (asynchronous,IBM-compatible bi-synch, synchronous,HDLC/SDLC) with full and complete modemcontrol lines, and 16 counter-timer channels.

Utilizing the highly advanced Zilog peripheralchips, (Z-80 SIO, PIO & CTCs), the SPIC board isfully programmable to serve as the foundation fora multi-user multi-tasking system. Each of theseven Z-80 peripheral chips can generate its owninterrupt vector, with daisy-chain priority levels.Each counter-timer channel can be programmedto monitor an interrupt vector line on the S-100bus. Each SIO channel can be drivenindependently with separate Tx/Rx clocks so yourperipherals can have varied baud rates from 110 to76,800 baud.

IOI-1045B Bare Board $49.95

IOI-1045K 2 CTCs, 1 SIO, 1 PIO ... $179.95

IOI-1045A A&T $239.95

IOI-1046K 4 CTCs, 2 SIO's, 1 PIO .. $219.95IOI-1046A A&T $299.95

Build It Yourself and Save $1850

Complete S-100 Micro-Computer Kit

4 Mhz Big Z CPU, 64K Memory Bank, Double-Ddisk controller, 12 slot mainframe, dual disk sub-assembly with 2 double density 8" disk drives &power supply, ADDS Viewpoint terminal, CP/M2.2, boot PROM, system monitor, & all necessarycables and manuals - PLUS FREE BusinessSoftware Package. Save over $1850.00 $2795.00

Jade Business Software

Now, for the first time, at an amazingly low price,CP/M and SDOS users can get an affordablebusiness software package. Just look at theseprograms! All come complete with basic code(written to run under CBASIC T), for easycustomizing and modification. All software isself-documenting. The package price includes aword-processing system. When printed on thesystem's printer, all files with the extensionxxxTOT. constitute a complete manual. Nomanuals are supplied with the package other thanas they appear on the disks. All software issupplied on 8" premium quality JADE Diskettes.Software sold as is. (Sorry, but at these low priceswe can not offer our usual friendly support andhandholding.)

Includes; General Ledger, Payroll, Invoicing,Inventory Control , Accounts Recievable, CashDisbursements, Fixed Assets, Cash Receipts, &Mailing List Management.Special Package Price $249.95

Printers

Accessories for Apple

Single Board Computers

BEST BUY in PRINTERS - Epson

MX-70 132 column, 80 CPS, 5x7 dot matrix, adjustable

tractor feed, & graphics

PRM-27070 List $459 $399.95

MX-80 132 column, 80 CPS, bi-directional/logic seekingprinting. 9 x 9 dot matrix, adjustable tractor feed, & 64graphics charactersPRM-27080 List $645 $474.95

MX-80FT same as MX-80 with friction feed and full

graphics added

PRM-27082 List $745 $574.95

MX-100 233 column, correspondencequality. ultra-highresolution graphics, up to 15" paper, friction feed &removable/adjustable tractor feed, 18 xl8 dot matrix, 80CPS, programmable forms handlingPRM-27100 List $945 $795.00

PRA-27084 Serial interface $69.95

PRA-27088 Serial intf&2K buffer .. $144.95

PRA-27081 Apple card $74.95

PRA-27082 Apple cable $22.95

PRA-27086 IEEE 488 card $52.95

PRA-27087 TRS-80 cable $32.95

PRA-27085 Graftrax II $95.00

PRA-27083 Extra ribbon $14.95

SPINWRITER - NEC

65 cps, bi-directional, letter quality printer with deluxetractor mechanism, both parallel and serial interfaces on-board, 16K buffer, ribbon, print thimble, graphics, micro-space justification, data cable, and self test/diagnosticROM.

PRD-55511 without 16K buffer ... $2795.00PRD-55512 with 16K buffer $2895.00

Accessories for TRS-80

DISK DRIVES for TRS-80

2396 more storage, 8 times faster, 40 track with free patch, 120

day warranty.

MSM-12410C Save $125.00 !!! $325.00

8" DISK DRIVES for MODEL II

2 double density drives with cabinet, power supply, & cables

END-000433 Kit $1050.00

END-000434 Assembled $1250.00

WCA-5036A Cable (required) $29.95

16K Atari .. . $359.95

ATARI 800 - Atari

Complete personal computer with high resolution colorgraphics, built-in RF modulator, 4 controller ports, internalspeaker, I6K RAM & 8K ROM

SYO-2080A 16K Atari 800 $759.95

Atari 800 with 32K of RAM $799.95

Atari 800 with 48K of RAM $849.95

SYO-2040A WK Atari 400 $359.95

MSM-330810 Disk drive $595.00

MSM-330815 Dual drive $1395.00

IOX-5050A 850 interface $199.95

MEX-16853K WK RAM module $69.95

SFI-241011005 Visicalc $184.95

16K MEMORY UPGRADE

Add 16K of RAM to your TRS-80, Apple, or Exidy in justminutes. We've sold thousands of these 16K RAMupgrades which include the appropriate memory chips fasspecified by the manufacturer), all necessary jumperblocks, fool-proof instructions, and our 1 year guarantee.

MEX-16100K TRS-80 kit $25.00

MEX-16101K Apple kit $25.00

MEX-16102K Exidy kit $25.00

16K RAM Card - Microsoft

(There is life after 48K)MEX-16300A A & T $174.95

Z-80* CARD for APPLE

Two computers in one, Z-80 & 6502, more than doubles thepower & potential of your Apple, includes Z-80* CPU card,CP/M 2.2, & BASIC-80CPX-30800A A&T $299.95

APPLE CLOCK - Cal Comp Sys

Real time clock w/battery back-upIOK-2030A A&T $109.95

DISK DRIVE for APPLE

o'/i" disk drive with controller for your Apple

MSM-12310C with controller $475.00

MSM-123101 w/out controller $375.00

8" DRIVES for APPLE

Controller, DOS, two 8" double densisty drives, cabinet,

power supply, & cables

Special Package Price Kit $1399.95

PRINTER INTERFACE - CCS.

Centronics type I/O card w/ firmwareIOI-2041A A&T $99.95

AIO, ASIO, APIO - S.S.M.

Parallel & serial interface for your Apple (see Byte pg 11)

IOI-2050K Par&Serkit $139.95

IOI-2050A Par & Ser A & T $169.95

IOI-2052K Serial kit $89.95

IOI-2052A Serial A&T $99.95

IOI-2054K Parallel kit $69.95

IOI-2054A Parallel A&T $89.95

A488 - S.S.M.

IEEE 488 controller, uses simple basic commands,includes firmware and cable, I year guarantee, (see AprilBytepg 11)IOX-7488A A&T $399.95

CPS MULTICARD - Mtn. Computer

Three cards in one! Real time clock calendar, serial interface,

& parallel interface - all on one card,

IOX-2300A A & T $199.95

Apple-CAT - Novation

Software selectable 1200 or 300 baud, direct connect, auto-answer/auto-dial, auxiliary 3-wire RS232C serial port forprinter.IOM-5232A Save $50.00!!! $339.95

AIM-65 - Rockwell

6502 computer with alphanumeric display, printer. &keyboard, and complete instructional manuals

CPK-50165 IK AIM $424.95

CPK-50465 4K AIM $499.95

SFK-74600008E 8K BASIC ROM ... $99.95SFK-64600004E 4K assembler ROM $84.95

PSX-030A Power supply $64.95

ENX-000002 Enclosure $54.95

-IK AIM. 8K BASIC, power supply. & enclosureSpecial package price $675.00

Z-80* STARTER KIT - SD Systems

Complete Z-80* computer with RAM. ROM. l'O, display,keyboard, manual, and kluge area,

CPS-30010K Kit $369.95

CPS-30010A A&T $459.95

SYM-1 - Synertek Systems

/-pad.

Single board computer with 1K of RAM. IK of ROM. keLED display. 20ma & cassette interface on board.CPK-50020A A&T $249.95

Video Terminals

VIEWPIONT - ADDS

Detachable keyboard, serial RS232C interface, baud ratesfrom 110 to 19,200, auxiliary serial output port. 24 X 80display.tillable screen, international character setVDT-501210 Sale Priced $639.95

TELEVIDEO 950

Detachable keyboard, split screen with line lock, etched CRT.programmable function keys, on-screen status line, bufferedauxiliary port, 14 x 10 dot matrix, self test, serviced nation-wide by General ElectricVDT-901250 List $1195.00 $995.00

Video Monitors

Leedex / Amdek

Reasonably priced video monitorsVDM-801210 Video 100 12" B&W .. $139.95VDM-801230 Video 100-80 12" B& W $179.95VDM-801250 12" Green Phospor .... $169.95VDC-801310 13" Color I $379.95

13" COLOR MONITOR - Zenith

The hi res color you've been promising yourselfVDC-201301 $449.00

12" GREEN SCREEN - NEC

20 MHz, P31 phosphor video monitor with audio,exceptionally high resolution - A fantastic monitor at avery reasonable priceVDM-651200 12" monitor $269.95

EPROM Erasers

EPROM ERASERS

L.S. Engineering UV eraser for up to 48 EPROMsXME-3200 A&T $39.99

Faster Service.

S-100 PROM Boards

S-100 Memory

S-100 CPU

PB-l - S.S.M.

2708. 2716 EPROM board with built-in programmer

MEM-99510K Kit $154.95

MEM-99510A A&T $219.95

PROM-100 - SD Systems

2708. 2716. 2732. 2758. & 2516 EPROM programmer

MEM-99520K Kit $219.95

MEM-99520A Jade A&T $269.95

EPROM BOARD - Jade

16K or 32K uses 2708's or 2716's, IK boundary

MEM-16230K Kit $79.95

MEM-16230A A&T $119.95

S-100 Video

VB-3 - S.S.M.

80 characters x 24 lines expandable to 80x48 for a full pageof text, upper & lowercase, 256 user defined symbols, I60x192 graphics matrix, memory mapped, has key boardinput.

1OV-1095K 4 MHz kit $349.95

IOV-1095A 4 MHz A&T $439.95

IOV-1096K 80 x 48 upgrade $39.95

VDB-8024 - SD Systems

80 x 24 I/O mapped uideo board with keyboard I/O. andon-bnard Z-80 A*.

IOV-1020K Kit $399.95

IOV-1020A Jade A&T $459.95

VIDEO BOARD - S.S.M.

6-4 characters x 16 lines, 128 x 48 matrix for graphics, fullupper/lower case ASCII character set, numbers, symbols,and greek letters, normal/reverse/blinking video, S-100.

IOV-1051K Kit $149.95

IOV-1051A A&T $219.95

IOV-1051B Bare board $34.95

Motherboards

ISO-BUS - Jade

Silent, simple, and on sale - a better motherboard6 Slot (5'A" x8'A")

MBS-061B Bare board $19.95

MBS-061K Kit $39.95

MBS-061A A&T $49.95

12 Slot (93A" x 8%")

MBS-121B Bare board $29.95

MBS-121K Kit $69.95

V1BS-121A A&T $89.95

18Slot(14'/j"x8%")

WBS-181B Bare board $49.95

WBS-181K Kit $99.95

WBS-181A A&T $139.95

Mainframes

MAINFRAME - Cal Comp Sys

12 slot S-100 mainframe with 20 amp power supply

ENC-112105 Kit $379.95

ENC-112106 A&T $409.95

DISK MAINFRAME - N.P.C.

Htilds 2 8" drives and a 12 slot S-100 system. Attractivemetal cabinet with 12 slot motherboard & card cage, powersupply, dual fails, lighted switch, and other professionalI'calurvs

ENS-112325 with 25 amp p.s $699.95

■cle 179 on inquiry card.

EXPANDORAM II - S D Systems

4 MHz RAM board expandable from 16K to 64K

MEM-16630K 16K kit $275.95

MEM-32631K 32K kit $295.95

MEM-48632K 48K kit $315.95

MEM-64633K 64K kit $335.95

Assembled & tested add $50.00

64K RAM - Calif Computer Sys

4 MHz bank port / bank byte selectable, extendedaddressing, 16K bank selectable, PHANTOM line allowsmemory overlay, 8080 / Z-80 / front panel compatible.MEM-64565A A&T $575.00

32K STATIC RAM - Jade

2 or 4 MHz expandable static RAM board uses 2114L's

MEM-16151K 16K4MHzkit $169.95

MEM-32151K 32K 4 MHz kit $299.95

Assembled & tested add $50.00

16K STATIC RAM - Mem Merchant

4 MHz 16K static RAM board. IEEE S-100. bank selectable.Phantom capability, addressable in 4Kblocks, "disable-able"in IK segments, extended addressing, low powerMEM-16171A A&T $174.95

S-100 Disk Controller

DOUBLE DENSITY - Cal Comp Sys

5'/i" and 8" disk controller, single or double density, withonboard boot loader ROM. and free CP-'M 2.2* andmanual set.IOD-1300A A&T $369.95

VERSAFLOPPY II - SD Systems

New double density controller for both 8" & 5'A"

IOD-1160K Kit $339.95

IOD-1160A A&T $379.95

Disk Drives

8" DISK DRIVES

Highly reliable double density floppy disk drivesShugart 801R single sided, double density

MSF-10801R SA-801R $425.00

Special Sale Price 2 for $790.00

Shugart 851R double sided, double density

MSF-10851R SA-851R $595.00

Special Sale Price 2 for $1150.00

Siemens FDD100-8D2 single sided, double density

MSF-201120 $385.00

Special sale price 2 for $750.00

Qume Datatrak 8 double sided, double densityMSF-750080 SA-851R compatible .. $599.95Special sale price 2 for $1160.00

JADE DISK PACKAGE

Double density controller, two 8" double density floppydisk drives, CP-' M2.2 (configured for controller), hardwareand software manuals, boot PROM, cabinet, power supply.fan, & cablesSpecial Package Price Kit $1395.00

5'A" Diskettes Box of 10 .. $22.008" Diskettes Box of 10 .... $24.00

» : ,hi

CB-2 Z-80 CPU - S.S.M.

2 or 4 MHz Z-80 CPU board with prouision for up to 8KofROM or 4K of RAM on board, extended addressing, IEEES-100, front panel compatible.

CPU-30300K Kit $239.95

CPU-30300A A&T $299.95

2810 Z-80* CPU - Cal Comp Sys

2/4 MHz Z-80A* CPU with RS-232C serial I/O port andon-board MOSS 2.2 monitor PROM, front panel compatible.CPU-30400A A&T $269.95

SBC-200 - SD Systems

4 MHz Z-80* CPU with serial & parallel I/O ports, up to 8Kof on-board PROM, software programmable baud rategenerator. IK of onboard RAM, Z-80 CTC.

CPC-30200K Kit $339.95

CPC-30200A Jade A&T $399.95

1/0-4 - S.S.M.

2 serial I/O ports plus 2 parallel I/O ports

IOI-1010K Kit $179.95

IOI-1010A A&T $249.95

IOI-1010B Bare board $35.00

Novation Cat Modem

-LimitedQuantity

IOM-5200A List price $189.95 $125.00

D-CAT 300 baud, direct connect modemIOM-5201A Special sale price $169.95

AUTO-CAT Auto answer/origiate. direct connectIOM-5230A Special sale price $239.95

Place Orders Toll Free

Continental U.S. Inside California

800-421-5500 800-262-1710

For Technical Inquires or Customer Service call:

213-973-7707

Computer Products

4901 W. Rosecrans, Hawthorne, Ca 90250

TKRMS of SALE: Cash, checks, credit cards, orPurchase Orders from qualified llrma and institutions.Minimum Order $15.00. California residents add 6%tax. Minimum shipping & handling charge $3.00.Pricing & availibility subject to change

16K Memory 8/$16.95

4116 300ns *"ALL MERCHANDISE 100% GUARANTEED CALL US FOR VOLUME QUOTES

LS SERIES

74LS00

25

74LS163

.95

74LS01

.25

74LS164

.95

74LS02

.25

74LS165

.95

74LS03

.25

74LS166

2.40

74LS04

.25

74LS168

1.75

74LS05

.25

74LS169

1.75

74LS08

.35

74LS170

1.75

74LS09

.25

74LS173

.80

74LS10

.25

74LS174

.95

74LS11

.35

74LS175

.95

74LS12

.35

74LS181

2.15

74LS13

.45

74LS189

9.95

74LS14

1.00

74LS190

1.00

74LS15

.35

74LS191

1.00

74LS20

.25

74LS192

.85

74LS21

.35

74LS193

.95

74LS22

.25

74LS194

1.00

74LS26

.35

74LS195

.95

74LS27

.35

74LS196

.85

74LS28

.35

74LS197

.85

74LS30

.25

74LS221

1.20

74LS32

.35

74LS240

1.85

74LS33

.55

74LS241

1.85

74LS37

.55

74LS242

1.85

74LS38

.35

74LS243

1.85

74LS40

.25

74LS244

1.75

74LS42

.55

74LS245

2.85

74LS47

.75

74LS247

.76

74LS48

.75

74LS248

1.25

74LS49

.75

74LS249

.99

74LS51

.25

74LS251

1.30

74LS54

.35

74LS253

.85

74LS55

.35

74LS257

.85

74LS63

1.25

74LS258

.85

74LS73

.40

74LS259

2.85

74LS74

.45

74LS260

.65

74LS75

.50

74LS266

.55

74LS76

.40

74LS273

1.65

74LS78

.50

74LS275

3.35

74LS83

.75

74LS279

.55

74LS85

1.15

74LS280

1.98

74LS86

.40

74LS283

1.00

74LS90

.65

74LS290

1.25

74LS91

.89

74LS293

1.85

74LS92

.70

74LS295

1.05

74LS93

.65

74LS298

1.20

74LS95

.85

74LS352

1.55

74LS96

.95

74LS353

1.55

74LS107

.40

74LS363

1.35

74LS109

.40

74LS365

.95

74LS112

.45

74LS366

.95

74LS113

.45

74LS367

.70

74LS114

.50

74LS368

.70

74LS122

.45

74LS373

1.85

74LS123

.95

74LS374

1.80

74LS124

2.99

74LS377

1.45

74LS125

.95

74LS378

1.18

74LS126

.85

74LS379

1.35

74LS132

.75

74LS385

1.90

74LS136

.55

74LS386

.65

74LS137

.99

74LS390

1.90

74LS138

.75

74LS393

1.90

74LS139

.75

74LS395

1.65

74LS145

1.20

74LS399

1.70

74LS147

2.49

74LS447

.37

74LS148

1.35

74LS490

1.95

74LS151

.75

74LS668

1.69

74LS153

75

74LS669

1.89

74LS154

2.35

74LS670

2.20

74LS155

1.15

74LS674

9.65

74LS156

.95

74LS682

3.20

74LS157

.75

74LS683

2.30

74LS158

.75

74LS684

2.40

74LS160

.90

74LS685

2.40

74LS161

.95

74LS688

2.40

74LS162

.95

74LS689

2.40

7400 SERIES

7400

.19

74128

.55

7401

.19

74132

.45

7402

.19

74136

.50

7403

.19

74141

.65

7404

.19

74142

2.95

7405

.22

74143

2.95

7406

.22

74144

2.95

7407

.22

74145

.60

7408

.24

74147

1.75

7409

.19

74148

1.20

7410

.19

74150

1.35

7411

.25

74151

.65

7412

.30

74152

.65

7413

.35

74153

.55

7414

.55

74154

1.40

7416

.25

74155

.75

7417

.25

74156

.65

7420

.19

74157

.55

7421

.35

74159

1.65

7422

.29

74160

.85

7423

.29

74161

.70

7425

.29

74162

.85

7426

.29

74163

.85

7427

.29

74164

.85

742B

.45

74165

.85

7430

.19

74166

1.00

7432

.29

74167

1.95

7433

.45

74170

1.65

7437

.29

74172

5.95

7438

.29

74173

.75

7440

.19

74174

.89

7442

.49

74175

.89

7443

.65

74176

.89

7444

.69

74177

.75

7445

.69

74178

1.15

7446

.59

74179

1.75

7447

.69

74180

.75

7448

.69

74181

2.25

7450

.19

74182

.75

7451

.23

74184

2.00

7453

.23

74185

2.00

7454

.23

74186

18.50

7460

.23

74190

1.15

7464

.39

74191

1.15

7465

.39

74192

.79

7470

.35

74193

.79

7472

.29

74194

.85

7473

.34

74195

.85

7474

.35

74196

.79

7475

.49

74197

.75

7476

.35

74198

1.35

7480

.59

74199

1.35

7481

1.10

74221

1.35

7482

.95

74246

1.35

7483

.50

74247

1.25

74B4

.50

74248

1.85

7485

.65

74249

1.95

7486

.35

74251

.75

7489

4.95

74259

2.25

7490

.35

74265

1.35

7491

.40

74273

1.95

7492

.50

74276

1.25

7493

.49

74279

.75

7494

.65

74283

2.00

7495

.55

74284

3.75

7496

.70

74285

3.75

7497

2.75

74290

.95

74100

1.00

74293

.75

74107

.30

74298

.85

74109

.45

74351

2.25

74110

.45

74365

.65

74111

.55

74366

.65

74116

1.55

74367

.65

74120

1.20

74368

.65

74121

.29

74376

2.20

74122

.45

74390

1.75

74123

.55

74393

1.35

74125

.45

74425

3.15

74126

.45

74426

.85

74490

2.55

74S00 SERIES

74S0074S0274S0374S0474S0574S0874S0974S1074S1174S1574S2074S2274S3074S3274S3774S3874S4074S5174S6474S65

74S74

74S85

74S86

74S112

74S113

74S114

74S124

74S132

74S133

74S134

74S135

74S138

74S139

74S140

74S151

74S153

74S157

74S158

74S161

74S162

.692.391.441.591.981.502.771.24.98.691.481.081.251.451.191.191.191.452.853.70

74S16374S16874S16974S17474S17574S18174S18274S18874S18974S19474S19574S19674S19774S20174S22574S24074S24174S25174S25374S257

3.754.655.441.091.094.472.953.95

14.952.951.894.904.25

14.958.953.983.751.907.451.39

74S25874S26074S27474S27574S28074S28774S28874S28974S30174S37374S37474S38174S38774S41274S47174S47274S47474S48274S57074S571

1.49

1.8319.9519.952.904.754.456.986.953.453.457.955.752.989.9516.8517.8515.607.807.80

T.V.

CIRCUITS

MC1330

1.89

MC1350

1.29

MC1358

1.79

LM380

1.29

LM386

1.50

LM565

.99

LM741

.29

LM1310

2.90

LM1800

2.99

LM1889

2.49

MISC.

8T26

1.69

3242

9.95

8T28

2.49

AY5-1013 3.95

8T95

.99

TR1602

4.95

8T96

.99

IM6402

7.95

8T97

.99

1771

24.95

8T98

.99

1791

36.95

1488

.99

UPD765

39.95

1489

.99

8272

39.95

DM8131

2.95

1793

49.95

CMOS

74C00

.35

74C373

2.75

4018

74C02

.35

74C374

2.75

4019

74C04

.35

74C901

.80

4020

74C08

.35

74C902

.85

4021

74C10

.35

74C903

.85

4022

74C14

1.50

74C905

10.95

4023

74C20

.35

74C906

.95

4024

74C30

.35

74C907

1.00

4025

74C32

.50

74C908

2.00

4026

74C42

1.75

74C909

2.75

4027

74C48

2.10

74C910

9.95

4028

74C73

.65

74C911

10.00

4029

74C74

.85

74C912

10.00

4030

74C76

.80

74C914

1.95

4034

74C83

1.95

74C915

2.00

4035

74C85

1.95

74C918

2.75

4040

74C86

.95

74C920

17.95

4041

74C89

4.50

74C921

15.95

4042

74C90

1.75

74C922

5.95

4043

74C93

1.75

74C923

5.95

4044

74C95

1.75

74C925

6.75

4046

74C107

1.00

74C926

7.95

4047

74C150

5.75

74C927

7.95

4049

74C151

2.25

74C928

7.95

4050

74C154

3.25

74C929

19.95

4051

74C157

1.75

74C930

19.95

4053

74C160

2.00

4000

.35

4060

74C161

2.00

4001

.35

4066

74C162

2.00

4002

.25

4068

74C163

2.00

4006

.95

4069

74C164

2.00

4007

.29

4070

74C165

2.00

4008

.95

4071

74C173

2.00

4009

.45

4072

74C174

2.25

4010

.45

4073

74C175

2.25

4011

.35

4075

74C192

2.25

4012

.25

4076

74C193

2.25

4013

.45

4078

74C195

2.25

4014

.95

4081

74C200

5.75

4015

.95

4082

74C221

2.25

4016

.45

4085

4017

1.15

4086

.95 4093

.45 4099

.95 14409

.95 14410

1.15 14411

.35 14412

.75 14419

.35 4502

1.65 4503

.65 4508

.80 4510

.95 4511

.45 4512

2.95 4514

.85 4515

.95 4516

1.25 4518

.75 4519

.85 4520

.85 4522

.95 4526

.95 4527

.55 4528

.55 4531

.95 4532

.95 4538

1.45 4539

.75 4543

.40 4555

.35 4556

.35 4581

.30 4582

.30 4584

.30 4585

.30 4702

.95 4724

.30 80C07

.30 80C95

.30 80C96

.95 80C97

.95 80C98

.95

1.95

8.95

8.95

9.95

12.95

2.95

.95

.65

1.95

.95

.95

.95

1.25

2.25

1.55

1.25

1.25

1.25

1.25

1.25

1.95

1.25

.95

1.95

1.95

1.95

2.70

.95

.95

1.95

1.95

.95

.95

12.95

1.50

.95

.85

.95

.95

1.20

DIP SWITCHES

4 position .85

5 position .90

6 position .90

7 position .95

8 position .95

CONNECTORS

TRANSISTORS

PN22222N39042 N 39062N3055IN4148IN 4004

10/1.00

10/1.00

10/1.00

.79

100/8.99100/8.99100/8.9910/6.9925/1.0010/1.00

RS232MALERS232 FEMALERS232 HOODS-100STS-100WW

3.253.751.253.954.95

LINEAR

VOLTAGE REG'S

7805T7808T7812T7615T7824T

.89.99.89.99.99

7905T7912T7915T7924T

.99.99

1.191.19

7805K7812K7815K

1.391.391.39

7905K7912K

1.491.49

78L0578L1278L15

.69.69

.69

79L0579L1279L15

.79.79.79

LM309KLM317TLM317K

1.491.953.95

LM323KLM337K

4.953.95

T =

TO-220 K

= TO-3 L = TO-92

LM301V

.34

LM741V

.29

LM308V

.98

LM747

.79

LM309K

1.49

LM748V

.59

LM311

.64

LM1310

2.90

LM317T

1.95

MC1330

1.89

LM317K

3.95

MC1350

1.29

LM318

1.49

MC1358

1.79

LM323K

4.95

LM1414

1.59

LM324

.59

LM1458V

.69

LM337K

3.95

LM1488

1.39

LM339

.99

LM1489

1.39

LM377

2.29

LM1B00

2.99

LM380

1.29

LM1889

2.49

LM386V

1.50

LM3900

59

LM555V

.39

LM3909V

.98

LM556

.69

LM3914

3.95

LM565

.99

LM3915

3.95

LM566V

1.49

LM3916

3.95

LM567V

1.29

75451V

.39

LM723

.49

75452V

.39

LM733

.98

75453V

.39

mm

VISA"

ll master charge ■

*—-^— ~^^r.^fj

JDR MICRODEVICES, INC.

1101 South Winchester Blvd.

San Jose, California 95128

800-538-5000 800-662-6263 (Calif.)

408-247-4852

T=TO-220 V=8PIN K=TO-3.

TERMS: For shipping Include $2.00 lor UPS Ground; $3.00for UPS Blue Label Aln $10.00 minimum order. Bay AreaResidents add 6Vi% sales tax Calif. Residents add 6%sales tax. We reserve the right to limit quantities and

Circle 181 on inquiry card.

4K STATIC RAMS 8/18.95

2114 LOW POWER 450nsALL MERCHANDISE 100% GUARANTEED CALL US FOR VOLUME QUOTES

8200

6800

Z80

8202

8205

8212

8214

8216

8224

8226

8228

8237

8238

8243

8250

8251

8253

8253-5

8255

8255-5

8257

8259

8272

8275

8279

8279-5

8282

8283

8284

8286

8287

8288

8289

45.00

3.50

1.95

3.90

1.85

2.50

1.85

4.95

19.95

4.95

4.50

14.95

5.50

9.85

9.85

5.25

5.25

9.00

7.00

39.95

29.95

10.50

10.50

6.65

6.65

5.80

6.65

6.65

25.00

49.95j

ICSOCKETS

1-100 100pcs

8 pin ST114 pin ST

116 pin STlis pin ST120 pin ST.22 pin ST|24 pin ST|28pinST140 pin ST

.13.15.17.20.29.30.30.40.49

.11.12.13 |.18.27 I27.27.32.39

ST = SOLDERTAIL

1 pin WW114 pin WW16 pin WW118 pin WW120 pin WW122 pin WW124 pin WW128 pin WW140 pin WW

.59.69.69.991.091.391.491.691.99

.49.52

.58.90.981.281.351.491.80

6800

6.95

6802

11.95

6809

37.95

6810

4.60

6820

4.95

6821

4.95

6828

9.95

6834

16.95

6840

14.95

6843

42.95

6844

44.95

6845

29.95

6847

15.95

6850

4.75

6852

5.75

6860

10.95

6862

11.95

6871

25.95

6875

6.95

6880

2.95

6502

6502

6502A

6504

6505

6520

6522

6532

6551

6.9512.956.958.954.959.9514.9514.95

Z80

Z80A

Z80B

Z80-PIO

Z80A-PIO

Z80-CTC

Z80A-CTC

ZB0-DART

Z80A-DART

Z80-DMA

Z80A-DMA

Z80-SIO/0

Z80A-SIO/0

Z80-SIO/1

Z80A-SIO/1

Z80-SIO/2

Z80A-SIO/2

Z80-SIO/9

Z80A-SIO/9

8.959.9519.956.508.606.508.6515.2518.7517.5027.5023.9528.9523.9528.9523.9528.9517.9522.95.

MPU'S

8035

8039

8080A

8085

8086

8088

8155

8156

8185

8185-2

8741

8748

8755

16.9519.953.9512.9599.9539.9511.9511.9529.9539.9539.9569.9549.95

BEFORE YOU BUY CALLJDR FOR THE BEST PRICE.

800-662-6233

(CALIFORNIA RESIDENTS)

SEPTEMBER SPECIALS

41164116

150ns200ns

2708

2716 Intel and NEC

2732 Intel

2532 Ti and Hitachi

NEC

2.99

5.95

16.50

Z80AZ80AZ80A

8251A

UPD765

LM323K

LS240LS241LS244

PIOSIO/1

Intel(8272)

3.50ea

8 for 19.958 for 17.50

8 for 2.75ea

8 for 5.50ea

8for15.95ea

19.95ea

6.00ea

6.00ea

15.00ea

4.75ea35.00ea

10 for3.00ea

LS SPECIALS

99

LS245

1.90

99

LS373

.99

99

SL374

1.75

WW = WIREWRAP

(Sale Ends September 30, 1981)

LEDS

Jumbo Red 10/1.00Jumbo Green 6/1.00Jumbo Yellow 6/1.005082-7760 .43'CC .79MAN74.3'CC .99

MAN72.3'CA .99

DYNAMIC RAMS

4027 (250ns) 2.50

4116-150 (150ns) 8/21.95

4116-200 (200ns) 8/19.95

4116-300 (300ns) 8/16.95

k4164 (200ns) CALL

100pcs

2.002.652.352.00CALL,

STATIC RAMS

100pcs

2101 (450ns) 1.95 1.85

2102-1 (450ns) .89 .85

21L02-1 (LP) (450ns) 1.29 1.15

2111 (450ns) 2.99 2.49

2112 (450ns) 2.99 2.792114 (450ns) 8/18.95 2.252114L-2 (LP) (200ns) 8/22.95 2.452114L-3 (300ns) 8/21.95 2.452114L-4 (LP) (450ns) 8/18.95 2.254044-4 (450ns) 3.49 3.254044-3 (300ns) 3.99 3.75TMM2016 (200ns) CALL CALLMB6116 (200ns) CALL CALL

LP = LOW POWER

EPROMS

Bpcs

1702

256x8

( 1us)

4.95

4.50

2708

1024x8

(450ns)

3.95

3.50

2716

(5v) 2048 x 8

(450ns)

6.95

5.95

2758

(5v) 1024x8

(450ns)

9.95

8.95

2716-1

(5v) 2048 x 8

(350ns)

12.95

11.95

TMS2716

2048 x 8

(450ns)

9.95

8.95

TMS2532

(5v) 4096 x 8

(450ns)

21.95

19.95

2732

(5v) 4096 x 8

(450ns)

17.95

16.95

PROMS

74S18874S28774S28874S38774S47174S47274S47474S57074S571

(82S23)(82S129)(82S123)(82S126)

(82S147)(82S141)(82S130)(82S131)

OCTSTSOCTSTSTSOCTS

32x8256x4

32x8256x4256x8512x8512x8512x4512x4

3.954.754.455.759.9516.8517.857.807.80

JDR MICRODEVICES, INC.

1101 South Winchester Blvd.

San Jose, California 95128

800-538-5000 800-662-6263 (Calif.)

408-247-4852

TERMS: For shipping Include $2.00 (or UPS Ground; $3.00lor UPS Blue Label Air, $10.00 minimum order. Bay AreaResidents add 6'/i% sales tax Calif. Residents add 6%sales tax. We reserve the right to limit quantities andsubstitute manufacturer. Prices subject to change withoutnotice.

Circle 181 on inquiry card.

WHAT'S NEW FROM CONSUMER COMPUTERS

Consumer Computers announces it's lowest prices ever.

Apple Cards and Hardware

16K Ram Card by CCI 130

Language System w/Pascal 379

Silentype Printer w/lnterface card 349

Hayes Micromodem II 299

Novation Apple-Cat II 339

Videx uideoterm 80 column w/graphics 269

Z-80 Softcard by Microsoft 299

16K RamCard by Microsoft 159

ABT Numeric Keypad (old or new kybrd) 110

ALF 3 voice Music Card 239

ALF 9 voice Music Card 169

Heuristics Speechlink 2000 259

Alpha Syntauri Keyboard System 1399

Corvus 10MB Winchester Disk system CALL

Lazer Lower Case Plus+ 55

Micro-Sci Disk Drives (A-40 & A-70) CALL

SSM AIO Serial/Parallel card A&T 189

Sup-R-Terminal 80 Column Card 329

SVA 2VX4 Megabyter 8" disk controller 589

SVA 2+2 Single Den. 8" disk controller 345

Versawriter Digitizer Pad 229

Digisector Camera interface 299

ThunderCtack Plus 119

Symtec Hi-Res Light Pen 210

Integer or Applesoft Firmwave card 145

Graphics Tablet 619

Parallel Printer interface card 135

Hi-Speed Serial interface card 135

Smarterm 80 column card 299

Joystick by Keyboard Co 45

Music System (16 Voices) 479

A/D + D/A interface 289

Expansion Chassis 599

lntrol/X-10 controller card 169

Clock/Calendar card 225

CPS Multi-function card 189

Supertalker SD-200 239

Romplus+ Card 135

Romwriter Card 149

Clock/Calendar Module 99

GP1B IEEE-488 Card 249

Asynchronous Serial Interface Card 129

Centronics Parallel Interface Card 99

Arithmetic Processor Card 299

We carry all CCS cards, please call for best prices.

Apple II Entertainment Software(Top Ten)

Raster Blaster 29

Alien Rain 23

Hungry Boy 24

Adventure by Microsoft 27

Sargon II Chess 32

Pulsar II 29

Space Eggs 29

Flight Simulator 34

Cosmos Mission (Space Invaders) 24

Worlds Greatest Black Jack game 40

WE OFFER HUNDREDS OF SOFT-WARE GAMES. PLEASE CALL ORWRITE FOR A LIST.

VIDEOTAPES

WE SELL HUNDREDS OFFEATURE FILMS ON VHSAND BETA VIDEO TAPE.CALL OR WRITE FOR APRICE LIST.

The versatile Apple Computer

NOWONLY

16K

$1025

48K

NOWONLY

$1129

64K

& NOW

ONLY

$1249

*16K Ram Card installed on 64K.

TOLL FREEORDER LINE

800-854-6654

California & outside continental U.S.

(714) 698-8088

International Telex 695-000 Beta CCMO

APPLE ///

These systems come complete with theinformation analyst software package and avideo monitor of your choice.

96K FOR ONLY $3495128K FOR ONLY $3995

DISK/// 450

SILENTYPE/// 329

AVAILABLENOW!

■ ■ ■ L^g^B | 1 il

NEC MICROCOMPUTER

PC-8001A 32K RAM COMPUTER CALL

PC-8012A I/O UNIT W/32K RAM CALL

PC-8031A DUAL MINI-DISK DRIVE UNIT CALL

Please write for more information about the NEC computer.

\

WithController

WithoutController

AppleDisk Drives

$519$439

Solution Softwarethe Apple U

Visicalc 3.3 169

CCA Data Management 85

DB Master 169

WordStar (Apple 80 co. version) 299

Super Text n 139

Desktop Plan II 169

Applewriter 65

Infotory 225

Landlord Apt. Mngmt 649

Stock Tracker by H&H 175

Easywriter 225

ASCII Express 59

Peachtree Business Software CALL

Applesoft Compiler 185

Visiterm 129

Visitrend/Visiplot 219

Real Estate Analyzer 89

Tax Preparer 99

DOS Toolkit 65

Tax Planner 99

Dow Jones Portfolio Evaluator 45

Dow Jones News & Quotes Reporter 85

Apple Fortran 165

Apple Pilot 129

Controller Gen. Bus. System 499

The Analyzer Dakin 5 :. • 519

Music Theory 45

Circle 94 on Inquiry card.

WHAT'S NEW FROM CONSUMER COMPUTERS

Buying Mail Order saves time, money and energy!

Atari Personal Computer

ATARI 800 16K

$749

ATARI 40016K $349

410 Program Recorder 65

810 Disk Drive 449

815 Dual Disk Drive (Dbl. Den.) 1295

820 40 Col. Impact Printer 349

822 Thermal Printer 349

825 80 Col Impact Printer (Cent. 737) 699

830 Acoustic Modem 159

850 Interface Module 159

Atari Light Pen 65

16K Ram Memory Module 149

16K RAM Memory Module (by ConComp) 89

Ohio ScientificChallenger Computer

4P

IP MOD II

$549$399

Exidy Sorcerer II

--"■*■»

We have the Sorcerer II in stock at unbeatableprices. Available in 16K, 32K & 48K models.Please Call for Price.

S-100 Expansion Unit 429

Word Processing Pac 179

Development Pac 89

PMC-80 Micro Computer

$599

16K

Compatible with TRS-80 Modeland software!

hardware

S-100

Quality S-100 cards available nowat incredibly low prices.

Assm &Kit Tested

CALIFORNIA COMPUTER SYSTEMS

Z-80 CPU 2810 n/a 229

64K Dynamic Ram board n/a 499

16K Static Ram 2 MHz n/a 249

16K Static Ram 4 MHz n/a 299

Dbl. Density Floppy Disk Controller n/a 299

12 Slot S-100 Mainframe n/a 349

SSM

Z-80 CPU CB-2 219

104 2 par. & 2 ser. 1/0 board 189

VB-3 80 * 24 Video board 329

VB-3 80 « 48 Video board 369

VB-2 I/O Mapped video board 64 » 16 .... 159PB1 PROM Prgmmr & EPROM board .... 139

SD SYSTEMS

EXPANDORAM I (2MHz Uses 4116 16Kdynamic RAM and is expandable 32K

to 64K 48K

64K16K32K48K64K

EXPANDORAM II (4MHz Uses4116 or 4164 dynamic RAM, isexpandable to 64K or 256Krespectively.

VERSAFLOPPY I Disk controllerVERSAFLOPPY II Disk controllerSBC100 2.5 MHz Z-80 w/I/OSBC-200 4 MHz Z-80 w/l/OPROM 100 EPROM programmer

We will beat any currently advertisedprice on S-100 boards

. 240. 255.275. 295. 250. 269. 289. 305250299299299210

279249379429219199

310325345365319339359375319369369369279

TOLL FREEORDER LINE

800-854-6654

California & outsidecontinental U.S.

(714) 698-8088

International Telex 695-000Beta CCMO

Use your Mastercard, Visa, AmericanExpress, Carte Blanche, Diners Club tocharge your order phone. Open 7 days.

Video Monitors

Amdek/Leedex Video 100 12" B&W 139

Amdek (Hitachi) 13" Cobr 359

NEC 12" Green Phospher Screen CALL

NEC 12" RGB Hi-Res Color CALL

Panasonic 13' Color 449

Sanyo 9" B&W 185

Sanyo 9" Green Phospher Screen CALL

Sanyo 12" B&W 269

Sanyo 12" Green Phospher Screen 285

Sanyo 13" Color w/excellent resolution 449

PRINTERS

Epson /~* \ 1MX-80 \ ,>/"%■ ■ t

Paper TigerIDS-460

$949

Anadex 9500/9501 w/ 2K Buffer 1299

C. Itoh Starumter 25 CPS 1499

C. Itoh Starwriter 45 CPS 1899

Espon MX-70 CALL

Epson MX-80 F/T CALL

Paper Tiger 1DS-445 699

Paper Tiger IDS-460 949

Paper Tiger 1DS-560 1249

Silentype w/Apple II interface card 349

Qume Sprint 5/45 2495

Silentype w/apple IIInterface

$349

How to Order:

Ordering Information: Phone orders using VISA,MASTERCARD, AMERICAN EXPRESS, DINERS CLUB,CARTE BLANCHE, bank wire transfer, cashiers or certifiedcheck, money order, or personal check {allow ten days toclear.) Unless prepaid with cash, please add 5% for shipping,handling and insurance minimum $5.00). California residentsadd 6% sales tax. We accept COD's. PO's accepted fromEducational Institutions. All equipment is subject to pricechange and availability without notice. All equipment is newand complete with manufacturer's warranty. Showroomprices may differ from mail order advertisement.

Send Orders to:

GOmgQaDODQD3

G®ncDpaO®[

Mail Order

8314 Parkway DriveLa Mesa, California 92041

Circle 94 on inquiry card.

CALL US TODAY FORSPECIAL SYSTEMPACKAGE PRICES...

Now is the time to buy a completesystem of your choice...

• CROMEMCO SYSTEM 2

• DYNABYTE

• NORTHSTAR

• SUPERBRAIN

Complete with printer and software.READY TO USE!!!

Participate in our expansion sale.

MiniMicroMart is moving to larger quarters to serveyou with a larger staff and with the largestinventory of systems and peripherals.

MiniMicroMart, Inc.

943 W. Genesee St.

Syracuse, New York 13204

(315)422-4467

478 BYTE September 1981 Circle 241 on inquiry card.

WE ARE MOVING TOLARGER QUARTERS!

Thank you ...

... for making our expansion possible and forhelping make us the leading distributorof microprocessor systems, terminalsand printers.

We are showing our appreciation byproducing a special catalog with thousandsof items at greatly reduced prices.Call or write today.

Help us move our inventory before we haveto move it.

MiniMicroMart, Inc.

943 W. Genesee St.

Syracuse, New York 13204

(315)422-4467

Circle 242 on Inquiry card. Bra September i981 479

1858 EVERGREEN • DUARTE, CALIFORNIA 91010 • TELEPHONE (213) 357-50C

V*

JUST WRAP KIT

Just Wrap tool for

1*

daisy chain wiring.

Tool strips as it

wraps and cuts.

o

Includes one 50 footspool of wire.

'#

Part No.

Description Price

jw-r

Just Wrap Tool $14.95

JWK-6

Tool w/4 Spools and

JUW1 24.95

R-JW*

50 Ft. Replacement

Wire 3.49

JUW-1

Unwrapping Tool 3.49

•Specify Color: Red, Blue, White or

Yellow.

Part No.

WSU30WSU30M

Regular Modified

Wrap Wrap

HAND WRAP TOOL

Description Price

Regular $6.95

Modified 7.95

TERMINALS

VWM

• .025(0,63mm)Square Post

• 3 LevelWire-Wrapping

• Gold Plated25 PER PKG.

WWT-1WWT-2

WWT-3WWT-4

INS 1

Description

Slotted Terminal

Single Sided

Terminal

IC Socket Term.

Double Sided

Terminal

Insertion Tool for

above

Price$4.98

2.984.98

1.98

2.49

SOCKET WRAP

ID

••••••••••••

n )< I5 I6 I7 18 19 20 21 22 23 2<Wrap-ID

12 It 10 ? « 7 i 5 < ' 2 I

Slipped ontosocket beforewrapping toidentify pins.

Bulk Bulk

Part # Price Price Part i Price Price

1410 1.49/10 5.50/100 22ID 1.49/5 5.95/50

16ID 1.49/10 5.95/100 24ID 1.49/5 5.95/50

18ID 1.49/10 5.00/50 28ID 1.49/5 6.50/50

20ID 1.49/5 5.00/50 40ID 1.49/5 5.00/25

$K> PRODUCTS

_ «j§P.C.B.

ttttte

ftSft$SJ&! TERMINAL

iaiar^ strips

T^H

flftk' The TS strips provide

positive screw activated

clamping action, accom-

modate wire sizes 14-30 AWG (1,8-0,

25mm

. Pins are solder plated copper,

.042 in

ch (1mm) diameter, on .200 inch

(5mm) centers.

Part No.

Description Price

TS- 4

4-Pole $1.69

TS- 8

8-Pole 2.59

TS-12

12-Pole 3.49

TS6MD

2-Pole Interlocking 3/1.79

DESOLDERINGPUMP

Easy one handoperation.Rugged all metalconstruction.ReplaceableTEFLON® Tip. Selfcleaning on each stroke.Suction precisely regulated for reliabledesoldering without damage to delicatecircuitry.DSPI Desoldering Pump

LOGIC PROBE

Compatible with all logic families us-ing a 4 to 15V power supply.Thresholds automatically programm-ed. Visual indication of logic levels toshow high, low, bad level or open cir-cuit logic pulses.

• 10 N sec. pulse responses

• 120 K input impedence.

• Automatic resetting memory.

• Includes tip with protective cap &coiled cord.

PRB-1 $36.95

LOGIC PULSER

Superimposes a pulse train (20 pps) ora single pulse onto the circuit nodeunder test without un-soldering IC's.

• Automatic polarity sensing

• 2 us pulse width

• Finger tip push button actuated

• Includes tip with protective cap &coiled cord.

PSL-1 $48.95

VACUUM VISE

Unique vacuum-basedlight duty vise forprecision handling ofsmall components andassemblies. RuggedABS construction. 1 V2" (32mm)'travel for maximum versatility,features screw lugs for perminstallation.

VV1

Vacuum Vice

$3.49

HOBBY-WRAPTOOLBW263

Auto-IndexingAnti-OverwrapModified Wrap

Part No. Description

BW2630 Tool

BT30 #30 Bit (not incl.)

BT2628 #28 Bit (not incl.)

BC1 Batteries & Charger

$19.85

3.95

7.95

14.95

INSERTION/EXTRACTIONTOOLS

Part No.

INS1416MOS1416

MOS2428

MOS40

EX1

EX2

Price$3.49

Description

14-16 pin Inserter

14-16 pin MOS Safe

Inserter

24-28 pin MOS Safe

Inserter

40 pin MOS Safe

Inserter

14-16 pin

IC Extractor

24-40 pin

IC Extractor

WK-7 IC

f-INSERTION K

lftj|?5.l— Complete IC In-serter/ Extractor KIndividual Corn-el h ponents (listedH. ~ above) $22.95

7.95

7.95

7.95

1.49

7.95

IC DISPENSER

Allows IC's to be dis-pensed from their tube 1at a time and picked upby insertion tools above.

• Dispenses 8-42 pinIC's • Compatable withall IC carrying tubes •Use with WK7 for MOS -safe insertion. •

Part No. DescriptionMDD1 1 Chan. Dispenser

MDD5 5 Chan. Dispenser

MDD10 10 Chan. Dispenser

* * *No Discount.

Circle 281 on inquiry card.

LL FREE ORDERING NUMBER 1(800) 423-7144

IDC CONNECTORS

RIGHT ANGLE HEADERS

SOLDER TAIL WIRE WRAP

Size Part No. Price

IDH10SRB $1.20IDH20SRB 1.90IDH26SRB 2.75IDH34SRB 3.75IDH40SRB 3.75IDH50SRB 4.75

Part No.

IDH10WRBIDH20WRBIDH26WRBIDH34WRBIDH40WRBIDH50WRB

PriceS2.604.155.356.257.359.20

.1" Spacing. Mounts on PC Board & Mateswith IDS Socket below. Ejector Bars ■ 4/1.00.

*

f

N t

25 PIN

'D"

CONNECTORS

Solder StyleMaleFemaleCover

Part No.DB25PDB25SDB25C

Price

$2.95

3.95

1.50

IDC Style

Male IDB25P 6.25

Female IDB25S 6.60

Cover IDB25C 1.60

Solder Style solders onto cable, IDCStyle crimps onto cable with vise. 9,15, 37 and 50 pin available also.

WIRE WRAP WIRE

#30 Wire Wrap Wire

Length

100/Bag

500/Bag

1K/Bag

2.5"

$1.38

$3.94

$6.81

3.0"

1.43

4.25

7.46

3.5"

1.51

4.57

8.11

4.0"

1.56

4.88

8.73

4.5"

1.63

5.21

9.39

5.0"

1.69

5.54

10.04

5.5"

1.74

5.92

10.69

5.0"

1.82

6.23

11.34

3.5"

2.11

7.08

12.99

7.0"

2.19

7.44

13.68

7.5"

2.29

7.78

14.40

3.0"

2.35

8.12

15.10

3.5"

2.40

8.46

15.80

9.0"

2.46

8.92

16.51

3.5"

2.53

9.15

17.22

10.0"

2.63

9.58

17.91

Ml lengths are overall, including 1" stripon each end. Choose from colors; Red,3lue, Black, Yellow, White, Green,Drange, and Violet.

EDGE CARD CONNECTORS

Size Part No. Price

10

IDE10B

$3.95

20

IDE20B

4.35

26

IDE26B

5.00

34

IDE34B

6.05

40

IDE40B

6.90

50

IDE50B

7.50

.1" Spacing. Crimps onto cable withordinary vise & mates with standard.062" Card Edge.

I w

CABLE PLUGS

Size

14162440

Part No.

IDP14BIDP16BIDP24BIDP40B

Price

$1.451.652.504.15

.1" Spacing. Crimps onto cable withordinary vise & plugs into standard ICSocket.

WIRE WRAP SUPPLIES

Size

Part No.

ICN083WBSG

Each.44

Tube

08

52x .39 =

= $20.28

14

ICN143WBSG

.53

30x .46 =

= $13.80

16

ICN163WBSG

.58

26x .50 =

= $13.00

18

ICN183WBSG

.78

23x .68 =

= $15.64

20

ICN203WBSG

1.00

21X .85 =

= $17.85

22

ICN224WBSG

1.07

19x .92 =

= $17.48

24

ICN246WBSG

1.09

17x1.09 =

= $15.98

28

ICN286WBSG

1.43

15x1.23 =

= $18.45

40

ICN406WBSG

1.85

10x1.60 =

= $16.00

Selective Plating provides gold in contactwhere it counts. 3-level wrap. Save by buy-ing sockets by the tube. All gold available atVaC/pin extra charge.

' * " No Discount

_

^

W

Solid Color

Color Coded ^{^l

Size

10 ft.

100 ft.

10 ft.

100 ft. \j

10

2.90

17.00

4.00

30.00

14

3.40

23.80

5.00

42.00

16

3.70

27.20

5.60

48.00

20

4.40

34.00

7.00

60.00

24

5.00

40.80

8.00

72.00

26

5.40

44.20

8.60

78.00

34

6.80

57.80

11.00

102.00

40

7.80

68.00

13.00

120.00

50

9.50

85.00

16.00

150.00

SOCKETS

1

Size Part No.

Price

10 IDS10B

$1.88

20 IDS20B

2.75

26 IDS26B

3.50

34 IDS34B

4.50

40 IDS40B

5.40

50 IDS50B

6.50

.1" Spacing. Crimps onto cable

with

ordinary vise & mounts to header sold

above.

WIRE KITS

Kit No. 1 - $9.95

250

3" 100

4%"

200

3%" 100

5"

100

4" 100Kit No. 2 - $24.95

6"

250

2%" 250

5"

500

3" 100

51/2"

500

3'/2" 100

6"

500

4" 100

6%"

250

4Va" 100Kit No. 3 - $34.95

7"

250

2%" 500

4Va"

500

3" 500

5"

500

3'/2" 500

51/2"

500

4" 500Kit No. 4 - $59.95

6"

■

500

2%" 1000

AVz"

1000

3" 1000

5"

'

1000

3%" 1000

5V2"

1000

4" 1000

6"

ORDERING INFORMATION

'repaid orders over $50 shipped prepaid viaJPS. All others add $3.00 for handling. VISA,vIC, COD's and open account orders will be;harged freight. $15 minimum order. $100ninimum open account order.

DISCOUNT SCHEDULE

Order

Amount

Discount and the name of

$15 - 99

Net

this magazine must be men-

100- 199

less 10%

tioned at time of order to get

200 - 499

less 15%

discount. Discount applies

500 - 999

less 20%

on all items except as noted,

1000 up

less 25%

"No Discount."

Circle 281 on inquiry card.

7400

TTFSo?

SN7400NSN7401NSN7402NSN7403NSN7404NSN7405NSN7406NSN7407NSN7408NSN7409NSN7410NSN7411NSN7412NSN7413NSN7414NSN7416NSN7417NSN7420NSN7421NSN7422NSN7423NSN7425NSN7426NSN7427NSN7429NSN7430NSN7432NSN7437N5N7438NSN7439NSN7440NSN7441NSN7442NSN7443NSN7444NSN7445NSN7446NSN7447NSN7448NSN7450NSN7451NSN7453NSN7454NSN7459NSN7460NSN7470NSN7472NSN7473NSN7474NSN7475NSN7476NSN747dNSN7480NSN7482NSN7483NSN7485NSN7486NSN7489NSN7490NSN7491NSN7492NSN7493NSN7494NSN7495NSN7496NSN7497NSN74100NSN74107NSN74109NSN74116NSN74121NSN74122N

4.60.49

1.75.39

1.95.29

SN74123NSN74125NSN74126NSN7412BUSN74132NSN74136NSN74139NSN74141NSN74142NSN74143NSN74144NSN74145NSN74147NSN74148NSN74150NSN74151NSN74152NSN74153NSN74154NSN74155NSN74156NSN74157NSN74158NSN74160NSN74161NSN74162NSN74163NSN74164NSN74165NSN74166NSN74167NSN74170NSN74172NSN74173NSN74174NSN74175NSN74176NSN74177NSN74179NSN74180NSN74181NSN74182NSN74184NSN74185NSN74186NSN74188NSN74190NSN74191NSN74192NSN74193NSN74194NSN74195NSN74196NSN74197NSN74198NSN74199NSN74221NSN74251NSN74273NSN74279NSN74283NSN74284NSN74285NSN74290NSN74298NSN74365NSN 74366 NSN74367NSN74368NSN74390NSN74393NSN74490N

2.952.952.95

.621.951.201.09

.67

1.19.78.78

.871.201.95

1.694.75

1.75.752.252.25

9.953.90

1.391.391.19.951.05

3.903.901.25

CMOS

CD4000CD4001CD4002CD4006CD4007CD4008CD4009CD4010CD4011CD4012CD4013CD4014CD4015CD4016CD4017CD4018CD4019CD4020CD4021CD4022CD4023CD4024CD4025CD4027CD4028CD4029CD4030CD4031CD4032CD4034CD4035CD4037CD4040CD4041CD4042CD4043CD4044CD4046CD4047CD4048CD4049CD4050CD4051CD4052CO4053CD4055CD4056CD4059CD4060CD4066CD4069CD4070CD4071CD4072CD4073CD4075CD4076CD4077CD4078CD4081CD4082CD4085.CD40S9CU4093CD4094

1.391.15.591.19

1.101.191.15

3.252.153.25.95

1.951.291.25

1.101.101.103.95

2.959.251.39

1.952.95

CD4098

CD4099

MC14408

MCI 4409

MC144t0

MC14412

MC14415

MC14419

CD4501

CD4502

CD4503

CO4505

CD4506

CD4507

CD4508

CD4510

CD4511

CD4512

CD4515

CD4516

CD4518

CD4520

CD4555

CD4556

CD4566

74C0O

74C02

74C04

74C08

74C10

74C14

74C20

74C30

74C32

74C42

74C48

74C73

74C74

74C85

74C89

74C90

74C93

74C95

74C107

74C151

74C154

74C157

74C160

74C161

74C163

74C164

74C173

74C174

74C175

74C192

74C193

74C195

74C240

74C244

74C373

74C374

74C922

74C923

MM80C95

MMH0C97

2.292.2512.9512.9512.9512.958.95*4.95.391.65

1.191.392.75

.991.35

1.795.951.191.191.491.192.493.502.101.651.551.651.551.351.35

2.192.192.392.395.395.651.501.25

74LS00N

74LS01N

74LS02N

74LS03N

74LS04N

74LS05N

74LS08N

74LS09N

74LS10N

74LS11N

74LS12N

74LS13N

74LS14N

74LS15N

74LS20N

74LS21N

74LS22N

74LS26N

74LS27N

74LS28N

74LS30N

74LS32N

74LS33N

74LS37N

74LS38N

74LS40N

74LS42N

74LS47N

74LS48N

74LS51N

74LS54N

74LS55N

74|_S73N

74LS74N

74LS75N

74LS76N

74LS78N

74LS83AN

74LS85N

74LS86N

74LS90N

74LS92N

74LS93N

74LS95N

74LS96N

74LS107N

74LS109N

74LS112N

74LS113N

74LS114N

74LS122N

74LS123N

74LS124N

74LS125N

74LS126N

74LS132N

74LS136N

74LS138N

74LS139N

74LS145N

74LS148N

74LS151N

74LS153N

74LS154N

74LS155N

74LS156N

74LS157N

74LS158N

74LS160N

74LS161N

74LS162N

74LS163N 1.05

74LS164N74LS165N

74LS166N

74LS168N

74LS169N

74LS170N

74LS173N

74LS174N

74LS175N

74LS181N

74LS190N

74LS191N

74LS192N

74LS193N

74LS194N

74LS195N

74LS196N

74LS197N

74LS221N

74LS240N

74LS241N

74LS242N

74LS243N

74LS244N

74LS245N

74LS247N

74LS248N

74LS249N

74LS251N

74LS253N

74LS257N

74LS258N

74LS259N

74LS260N

74LS261N

74LS266N

74LS273N

74LS275N

74LS279N

74LS283N

74LS290N

74LS293N

74LS295N

74LS298N

74LS324N

74LS347N

74LS348N

74LS352N

74LS353N

74LS363N

74LS365N

74LS366N

74LS367N

74LS36SN

74LS373N

74LS374N

74LS375N

74LS377N

74LS385N

74LS386N

74LS390N

74LS393N

74LS395N

74LS399N

74LS424N

74LS668N

74LS670N

81LS95N

81LS96N 1.69

81LS97N 1.69

81LS98N 1.69

1.151.15

2.20

1.15 .

1.15.95

1.151.691.691.691.691.492.201.10

1.754.40

1.9S1.19

1.891.89

1.702.352.951.752.29

LINEAR

5.95

1.49.992.95

78H0578M0678M.G.LM105HLM108AHLM300H .79

LM301CN/H .35LM304H .98

LM305H .89

LM306H 3.25

LM307CN/H .29LM308CN/H .98LM309K 1.49LM310CN 1.25LM311DOI/H .89LM312H 1.75LM317T 1.70

LM318CN/H 1.49LM319N/H 1.25LM320K-XX' 1.35LM320T-XX* 1.39LM320H-XX' 1.25LM323K 4.95

LM324NLM337KLM338KLM339NLM340K-XX* 1.75LM340T-XX* 1.25LM340H-XX' 1.25LM344H 1.95

LM348N 1.20LM350K 5.60LM358CN .98

LM360NLM372NLM376NLM377NLM380CN/N 1.25

5.956.95

1.49

LM381NLM383T

LM386N

LM387N

LM390N

NE531V/T

NE555V

NE556N

NE561T

1.79

19.95

NE565N/H 1.25

1.751.502.75.99.29.75.391.95

NE566HWNE567WHNE592NLM702HLM709N/HLM710N/HLM711N/HLM715NLM723N/KLM733N/H .98LM739N 1.15

LM741CN/H .33LM741CN-14 .19LM747N/H .75LM748N/H .39LM760CN 2.95LM1310N 1.90MC1330 195

MC1350 1.95

MC1358 1.75

LM1414N 1.90

LM1458CN/N .49

MC1488N

MC1489N

LM1496N

LM1556N

LM1820N

LM1850N

LM1889N

LM2111N

LM2900N

LM2901N

LM2917N

CA3013T

CA3018T

CA3021T

CA3023T

CA3035T

CA3039T

CA3046N

LM3053N

CA3059N

CA3060N

CA3062N

LM3065N

CA3080T

CA3081N

CA3082N

CA3083N

CA3086N

CA3089N

CA3096N

CA3097N

CA3130T

CA3140T

CA3146N

CA3160T

CA3190N

CA3410N

MC3423N

MC3460N

SG3524N

CA3600N

LM3900N

LM3905N

LM3909N

LM3914N

LM3915N

LM3916N

RC4131N

RC4136N

RC4151N

F1C4194TK

RC4195TK

ULN2001

ULN2003

SN75450N

SN75451N

SN75452N

SN75453N

SN75454N

SN75491N

SN75492N

SN75493N

SN75494N

TL494CN

TL496CP

.99.891.50

2.502.952.191.993.492.992.751.291.291.493.193.194.951.491.29

1.55

3.491.991.301,192.491.191.95

3.95

3.953.39

.89

4.20

ADVANCED

COMPUTERPRODUCTS

3 7225 Graphics Plotter 1795 00

3 16K Memory Module 265 00

1 5 1/41' Dual Master Fie* Disk Drive. 2100003 5 1/4" Single Masler Flex Disc Dnve1295 00

3 Personality Module 700 00

» ROM Drawer 40 00

1 Plotter/Printer ROM 130 00

D Input/Output ROM 260 00

3 Matrix ROM 130 00

3 Serial Inlerlace (RS-232C)

HP-83 $1895.Hp-.11: Powerful, Yel Eaty to Use

• TheHP-41 communicates withHP 41-CV you in words as well as numbers

■ • You can customize Ihe HP-41 loyour own design• Programming is last and easy• Continuous Memory saveseverything• Optional Peripherals allow youto expand capabilitiesHP-41 System I 398 00

u..,.„ HP-41 System II 675 00

HP-41CV HP-Card Reader 178.00

275.00 HP-Optical Wand 105 00

HP-41 C HP-Plolter'Printer 315.00

19B.0Q HP-OuarJ RAM 85 00

icippkz computer

v Sales and Service

Apple II® 64K

• Z-80Softcard Maxi-SvstPm

• 16K Ram Card mdAI Oy&lBIII

• Disk II w/controller

• Apple II w/48K Call for more pricing!

Total Value $271900 your price $222900save'- For Pascal System add $425'"'

mmpppki H hardware clearance up to 25% off

559 954599542595159 95189 00159 95169 9549.9529 953699 00

„ MINIMOVER-5

j^cr6"^1 ROBOTIC ARM

Completely ^^m^^L

nation or ^m

Assembly ^^H ^B ^B

lIC PnciDlfiS .A

■ Automation orRobolic Assembly j

• Education In fRobotic Priciples

• Artillcial Inteligence Experiments

• Computer Art and Games

$1695

00

Armbasic Software lor TRS-8

w'Applications ManualApphcations^RalcrencH Manu

$39"$16"

California Computer Systems 2200

SUPER S-100 BUY!

• 12 Slot Mainframe

• 64 Dynamic RAM

• CP/M™ 2.2

• Z-60CPU 4 MHz w/Serlal 10

• Double Density Disk Controller

• Interface to Vista V-1000 Chassis

SPECIAL PACKAGE PRICE

FOR COMPLETE SYSTEM

with (2) Shugart Double Density

Floppys mounted. add 1495.°°

1899.°°

Proto Clips

14-P.nClip PC-) 4

16-PmCltp PC-16 .

LM-Pin Clip PC-24

.10-Pin Clm PC-40

Proto Boards

1695 PB-104. .. 54.00

1B0O PB-203 . 97 00

2100 PB-203A 14900

25 00 PB-203A-Ki1 129 0043 00

LV«W--U!»!ife

AUTO-CAT

Automatic AnswerDirect Connect0-300 Band

List 27995ACP 24595

PAT™ List 198°°

Answer Originate ACP 1 69°

D-CAT™

direct Connect \0-300 Band.

List 249"- ACP18900

Rockwell Sin9le BoardComputers

AIM65w/1K 435.00

AIM65w/4K 475.00

8K BASIC ROM 99.00. 4K ASSEMBLER ROM 84.00

■ POWER SUPPLY 64.95

ENCLOSURE 49,95

TOTAL SYSTEM w/4K 669.00

SYNERTEKSYM-1 239.00

SD Z-B0 STARTER KIT 367.00

SD Z-80 STARTER KIT AST 450.00

SD SBC 100 Z-80 A&T 367.00

SD SBC 200 Z-80 A&T 399.00

RCACOSMACVIP 199.00

CROMEMCO Z-80 SBC 449.00

OalssBvar'-UninmrruplaOle PS

CCS Pirill.1 Card TT

Vac«lyiBi'"Voii;eCari] . ..

Vis>on B0'-80»J4 Card

Apple MiSpeaflSer

Vision 4O'"40 col onhancnmoni

A 600 Quad Dnni5ly6' Conlrolloi

595 00

MicroaollZBOSollcard . .

Apple Grjph.es Tab

SSU AlOSerialJParaliellO

Apple Prototype Cai

CCS Asynchronous 7710 A Sanal

Apple Joyslick "GESU"

pppte/ff TPrj^

New #appta software

Visicalc— Now Belter Than Ever 169.00Visiplot—Graph your

Visicalc Worksheets 149.00Visitrend/Visiplot—Visiplot

w/Trend Analysis 239.00Visidex—The Ultimate

DBMS Visicalc Compatible 219.00Visi term—Communicate

w/olher Systems 209.00

BPI General Ledger 299.00

BPI Accounts Receivable 299.00

BPI Inventory 299.00

Stockfile Inventory System 349.00

Infotory Inventory System 289.00

Microcom Microcourter 229.00

Microcom Microlelegraph 229.00

Accounting Plus II Biz Pkg. 1250.00

Stoneware DB Master 189.00Stoneware Utility Pkg (For above) 89.00

ACS BASIC ACCOUNTaccounting syslem inc

Buy

System

and

Save

We only offer AppleCPM software whichhas been evaluatedby our software stalf

WORDSTARThe Benchmark ofWordprocessing software requires Z-B0& 80x24 349.00

VTS-80 CP/M-Wordprocessor has noscreen menus uses new keycaps(supplied) to display Key functions

319.00 NewMAILMERGE-A Wordslar Enhance-ment Pkg. allows lorm-letter genera-tion & chained printing 169.00SPELLGUARD-Wilt proofread Wordstar& VTS-80 Text files against anexpandable 20,000 word dictionary

169.00SUPER SORT-Will sort, merge. &perlorm record selection on yourCP/M Data Files 169.00

FORTRA 80-By Microsoft 195.00

COBOL 80 By Microsoft 749.00

NG SYSTEM, Total

udes G/L, A/R, A/P.699.00 New

Breakthru in Apple II* Mass Storage!

Vista A800 Quad Density DMA 8" DiskController i

*

S.8BB

ly$595°

I Special Complete Subsystem Offer

• V1000 w/two Qume Datatrack 8 • Cable, ready to run

• A800 Apple II 8" Disk Controller

Total Value $293900 your price$249500

AATARI 800 & 400

r-\ Personal Computer SystemATARI 800 $799°°ATARI 400 $37500

ATARI 80O Includes: Computer Console, BASIC Lang. Cartridge, BASICLanguage Programming Manual. 800 Operator's Manual w/Notebook,16K RAM Module, Power Supply. TV Switch Box.

BiOuisc Drive

Program RecorderSilftn - HDD C.mlrj,..EaucawyiSysitm Masler CAtari BASICAssemble r DeougBaskets ■■

Ctynjujie' Cness

.499.00 Home f,ranee

295 00 [taulrM 1,11m Cruuni rnfrwi

795.00 uS h.sw>

J9 95 US Govtrnmrjnl

5-1 % SustrwsiVV Sfcii'i

189.95 we<J m.siop, (Weslern,

69D0 Bisk Sn.motj,

Counseling Proceou'es

e 2800 Punciow D< iccoumnrj

5500 Prices

55 00 o-eat taswi sEnpir.

^?03 Buimess Commurpcjiens

«?00 BKC PSttGMCjy

42005500

{HKlrvt rVMnc

'jjfle n S^S'C P-ajramm rBASlC UJmf Protjrir^iIII Oi Ir.n3k S^M Mtmtn Mock.*16k HAW MtiTtCDV Malu.e

□■si =i< Maiaaf.

P.O. Box 17329 Irvine, Calif. 92713

Direct Order Lines: (714) 558-8813

(800) 854-8230 or (800) 854-8241

Circle 8 on Inquiry card.

DRIVER'S LICENSE ff OR MAJOR CREDIT CARDa IS REOUIREDONALLCHECKS. MONEY ORDEROR CASHIER CHECK WILL FACILITATE THESHIPMENT OF YOUR PURCHASE.

X ^^COMPUTER

^AI^DUCTS

FIRST TO OFFER PRIME PRODUCTS TO THE HOBBYIST AT FAIR PRICES!

1. PrOWeil Quality Factory tested products only. S~Sa!*~\

2. Guaranteed Satisfaction ( 4i^f

Call For Special School Discounts \&?9.95

"V-DRIVE"

THE LAST WORD IN 8"FLOPPY-DISK ENCLOSURES

THE VISTA V-1000 FLOPPY DISK DRIVE SUBSYSTEM

• UtMtMM3Mtnrun4sUH(yKXBataan«pDSiinng^rr>uiUxi* Bullto mKtanMyind etetncaiy accomodate tnf sried 4«w- reJutria, f* "wl P****8- rtfl MnfUMI iW Sricart top* 4» aim art B- ndi WMmmg lapn hys • Strapopacity trumO) lo40magatycs * irdusfl^ o*«y catxrW a<Bi dr east icrttwef •Mats * UL in) OSMA surriaros • Adooerai Savtiptf Front Ml rear rwm rad imMirjrtB! it no on charge ino tus-j AM) • Desk or rack mutaDle • hutjesmnrllaiarairtni«ttraTnc'.«»i*^aaa^mcuitno • ""*■. a* am to my wa an! marts-arcs

DISCOUNT PRICES

CAWMET $ 395

CABINET m 12) snft sttO Ahs BflOWkg vmt a«»y 4 car*) $1495CABINET me-..Ji mw^osr* irekilrgcc** w. * cat* $1995

«^X for TRS80*MODELI,

jj^ PMC 80, ZENITH H89,

NTqS) «. S-100, etc.

^°.^ ONLY 31000 ea.

MODEL V-801,

80 TRACKS, SS

ONLY 42500 ea.

2 DRIVE CABLE . 29.95 4 DRIVE CABLE.. 39.95

J|r MOSTEK MK4015#JjF 4K Dynamic RAM

i' Refresh while supply lasts only .**yPin equivalent to MK4027 except has 1 ms.

S-100 WW

$2.99 each

IRST QUALITY AT SURPLUS PRICE

2708 EPROMS

PRIME-450 Ns.8 for $29.95

4K STATIC RAM SELL-OFF

Zilog 6104-4

Same as TMS 4044 but designed specificallyfor Z-80 based systems. This is full-spec4Kx 1 RAM. 450 Ns.

While supply lasts $1.49 each.

TTTTTTTTT

SPECIAL PURCHASE$59.95 Limited Supply $59.95

16K Altair RAM Boards. Fully Populated as is.

FLOPPY DISK DRIVES

QUME1 DaiatrackB

• Double Sided

• Double Density

ACP LOW PRICE $569.95

a Model FDD I20-8D .

Tandom TM1GO-1 5',." Dial

MPI B5t.5V.40 HacksSfiuaati fUUOGVSV 35 tra

Shurjart 600/601 fl 8"Siemens Shuoart CompatilPERSCI Model 277 Dual.MPI B52 5V0ual... ...

WANGO/SIEMENS82.

MPI 91 Double Track Density Single Side, t

MPI 92 Double Track Density Double Sid

6800 MICROMODULE" PRICE LIST

MODEL NO DESCRIPTION PRICE

9600A

9609

9601

9602

9603

960-1

9605

9610

$24.95 TRS-80/APPLE $24.95

MEMORY EXPANSION KITS.4116'S. 16K (200/250 ns.)

e pes for S24.95 n Annu tiiy I

Call For Volume Pricing ■■«■•■

16K

CENTRONICS PRINTER

Model 737

• Centronics complete printer

• The737haseverylhing Checkand compare Ihe features

• New low price $835.00

32K STATIC RAM BOARD

2 or4 MHz Expandable uses 2114L'sS-100

16K4MHzKi1 . 159.9516K4MHZA&T .217.95

32K MHz Kit 289.95

32K4MHzA&T ,339.00

Bare Board 39.95

Bare Bd. w/all partsless mem 99.95

NEW! from Zilog

Z-8 CPU comes withTiny Basie & debugprogram on the l.C.

BIPOLAR CPU SALE

Signetics 8 x 300 8 bit CPUWhile stock lasts 14.95 ea.

UV "Eprom" Eraser

, Model UVS-11E S69.95

Model S-S2T... S325.00

Pldli-.ISiCiiM' InUuuMjl Mnripl

non-linear systems. inc.TOUCH^-teST 20_

DIGITAL «.__._„.

MULTIMETER $31 995 |

(®

* BECKMANftv<S? DIGITAL MULTIMETERS

>-£ TECH 300 Digital Multimeter S110

™ TECH 310 Digital Multimeter * S

TECH 330 Digiial Multimeter $189

VC-201 Vinyl Carrying Case S10

DC-202 Deluxe Carrying Case S24

HV-211 High Voltage Probe $35

RP-221 RP Probe $35

Ct-231 AC Current Clamp 5W2

DL-241 DelxueTest Lead Kit S10

TL-242 Square Test Leads So

INTERSYSTEMS

The Preferred S-100 BoxThe new Series II CPU Board features a 4MHz Z-80A CPU and lull-feature front

panel. 20-slot actively terminated mother-board, with 25 amp power supply (50/60 Hzoperation, incl. 68 cfm fan).DPS-1, List $1795

ACP Price

$1499

SYSTEM 2A

with Z-80A CPU 4

MHz, 64K RAM, I/O Board, 20 slots, front

panel, double density disk controller

board. Full 1-year warranty.

List $3795 ACP Price $2995

16 Slot Mother BoardCard Cage8 Slol Mother BoardPower SupplyDC Input Power SupplyUtility Prolo BoardAntn Proc/Memory Module9612 Buttered Utility Proto Board

9616 32K EPP.OM/P.AM Module

9617 EPROM Programming Head9620 16 Channel Parallel t/O Module9622 Senai-Parailei I/O Module9627 16K Static RAM Module 470ns

9629 32K Static RAM 450ns9629A 32K Static RAM 200nS

9630 Card Extender9640 Multiple Programmable Timer9650 S Channel Duplex Serai I/O Mod9665 intelligent Tape Controller96103 32/32 I/O Module96702 Contact Closure Module

UNPOPULATED BOARDS (Also Available)

MICROPROCESSORS

ZOOOi i6bi!toBMb $18900

Z8002 16 bi! IOG4K . 14900

Z80 9.95

280A 13.95

F-8 (38501 1695

2650 16.95

CD 1802 9.75

8080A 4.75

8080A4MH1 1995

SALE 8085 14.95

8008-1 14 95

2901 9 90

2901A 1495

2903 4-o.t Supe'siice 29 95

TMS99O0JL 49.95

CP'GOO 39.95

6502 995

6502A 1695

IM6I00 29.95

6SOO 11.75

680OB20MHI 1995

6802P 1795

6035 14.95

8039 19.95

INS6073N 24.95

8755 49 95

8748 6995

6809 37.95

8086 69.95

ADVANCED SUPPORT

AM95H Anth, Processor . 175.00

9512 Anim Processor. 175 00

9513 Un,v Timing 79.95AM95' 7 DMA Controller 18.95AM95' 9 Universal Iniemjpl 18 95

Z-80 SUPPORT CHIPS

Z80-PIO 2 5 MHz 3.75

Z80A-PIO 40 MHz 12.95

Z80-CTC 2.5 MHj B.75

ZSOA-CTC 4 0 MHz 12.95

ZBO-DMA 2.5 MHz . 29.95

Z80A-DMA 4 0 MHz . .36.95

Z80-5IO.'0 2.5 MHz 35.95

Z80A-SIO/0 4.0 MHZ 39.40

Z80-SIO/1 2.5 MHz 35.95

Z80A-SIO/1 4.0 MHi ,39.40

ZBO-SIO/2 25MHz 35.95

Z80-SIO/2 4 0 MHz 39.40

8080/8088 SUPPORT

8155/8156 1/0 24.95

6755 I/O wiin Eprom 64.98

B202 Dyn Rem Com... 34.96

8205/74S 138 Docodar 3 95

82i260.li/o 275

8214 Priority Int. 5.25

8218 Bus Driver 2.75

622-1 Clock Go.-. 2.95

8224-4(4MHz) 9.78

8226 Bus Dnvsr 2.96

ST2G BusO/iver 2.95

8228 Sys ContfOI 4.50

823BSyS Conl 6.50

8243 HO Exp 9.50

8250Asyn.Comm 15.98

8251 Prog I/O 8.95

8253 Int Timer 12.95

8255 Prog. I/O 6.50

8257 Prog DMA ... . 16.95.

8259 Prog, irtl 15.95

8275 CRT Controller. . 45.958279 Prog Keyboard. 15 95

8800 SUPPORT CHIPS

6810 128- 6 Ram 4 75

5820 .6.50

6621 -6.50

6828 Priority Irtl 10.75

6834-1 512 « 8 Eprom ... .16.956845(HD46505CRTCont. .29.95

6847 Color CRT 29.95

6850 ACIA 5.95

6852 Serial /■.:.,.■>:.- 5.95

6860 Modem 10 95

6662 Modulator . 11.95

6671A 1 OMHtOSC . 25.96

6875 8.95

6880 Bus Or-ver . ... 2.19

MC6848B 19.95

88047 24.95

6502 SUPPORT CHIPS

6520 PIA 7.50

6522 Mult 11.96

6530-002 003.004.005.. . .21.95

6532 19.95

6551 . 19.95

BIPOLAR PROMS

We doCustom Programming

B2S23S330A6O0r74S18S 4.25

82S1l5(5l2x8)TS 12.95

82Sl23.'5810/74S2aB<32x8)TS. .4.2582S126/5803r74S3B7<258".4)OC 4.2582Si29.'5623/74S287(256x4)TS. 4,2582Si3Gv5604/74S570(512x4)OC 650

82S131/74S571 {S12x4)TS 6.95

82S137/74S573 [1024x4)TS ... 12.9582S141I3824/74S474 |512x8)TS 12.9582S147/74S472(512x8)TS .... 12.9574S471/6309(256x8)TS 7.95

MOS PROMS

27&4(8KxB)TS

69.95

2732(4KxB|TS

16.95

2716f2516.5V(2KxB)TS , -

TMS2716.i5V. 12V

17.95

2758.5V, fdMNU

7.50

2708 (45DNSI

. 5.75

2706 i650Nb>

.5.25

1702A

MM5203AQ

.14.50

CHARACTER GEN.

2513-001 15V) Upper

9 50

10 95

2513-AOM3(5V1 Lower ...

14 95

MCM66710 Ascli Shifted

12.95

MCM6674Q Math Symbol

MCM66750 Alpha Conlrol

13,45

UARTS/BAUD RATE

TRi602Bi5V 12V)

3 95

AV51013I5V irvi

4 95

AY51014A,A61?l514Vi

6 95

AVSI015A/1863I5VI

6 95

IM6402

IM6403

895

2360 USR1

9 95

I671B Asiros

24 95

...9.93

STATIC RAMS

2IL02 4S0nf. /efc\-£2IL02 250ns (^A<y2

an?. Vj£^

1 25

[l 593 75

1553 65

1 15J 55

295

285

2 65

2114NI450WS)

3.75

3.50

3.25

3114L-4S0m.(4O45)

4.75

425

3.95

695

760

6 90

EMMJ200A

8 75

7 95

7 95

7 25

AMDS 130/31

12 95

1101

195

175

1 25

P?iL'ri/<1J425|45ns)

9 95

835

6518 IK . 1 CMOS

7 95

7 95

•9.95

8.95

6 95

934(5

995

8.95

HiiO

DYNAMIC RAMS

416/411G 16K (16 Pin)

2 49

Se1olB41G's200 Ns

24.95

41158K(16Pin)

3.49

40504K . i (iBPnii

4 95

4060 4K . 1 (22 Pin|

4 95

4096 4K i 1 |16P.n)

40274Kx 1|16PinJIUPD414

. .4.95

5261 I9S f.AK 1103

5262 1 95 OHf\ jqq^

.95

MJO "95 RAMS 6605

7 95

$19.95 aoo2

SOCKETS

«Pln.

| Win Wrap 3 Laval

Tin

14

13

36

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38

59

64

20

29

99

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24

79

1 10

21

3B

85

1 20

36

58

1 25

i el

■10 |

60

1 40

1 89

ZERO INSERTION FORCE

LED READOUTS

DL7040.767FND35/FNDS01

)1|800) 800 KM

WS08Z-73*B 6

H=50a2-71fl0 i

HPSOK-7731 3

11L305

1IL308 2

IIL303 I

rut 1 !

I-UNIOA 1

XAN3061 ]

UN306? ]

HAN3063 ]

"AN 3064 J

WN30S? 3WN3QS3WN30S*WN308I

Conm AnxHCorom ClUKOeConn Cinaki-tCam CtnucCrxnn Amlf

i.'.iiun CilhMe

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Crjmni CjHw*

Canm AnaOc

Cow Anorje ltd OP

OvtrtKm CA. ten DP

Conm CjBvne Rqw OP

. Conm Ancde RqM DP

300 Own Conn Cjmalf Rigtil DP

i Conm CaBMDt Fbgr>i DP

IC SPECIAL PURCHASE

K2S09 64x9 RamOP8304 Octal OriverDAC66EXD/AConv.MC1650 Hi Speed A/DMC6852SSDAMC10145 16x4 ECL RamMK3850fF8CPUMK3853Stat

.46 78MQ6.89 79M0679 74157.29 74161.29 74C74an SlopWaich

SN75136

MC10210

LM339

LM710CN

LM711CN

ICM 7045Preci;

ICM 7207 Oscill; . _

Seven Decade Counler 7208

MC14433P 3' j 0>g<1 A/D ConvenerICL 8211 Voltage Reference

LM 1850N Ground Faull ICLM 2900N Quad AmpMierLM 2917 N Freg lo Volt ConvAV-3-3ii50 4'. digit DMMAY-5-3 507 40MHi DVM

MEM 4963 Mosiet Smoke Deiector27S08 32 x 8 Prom (IM 5600)LLN 2003A 7 channel Driver . .MCM 14505 64 bit Static Ram

MOC 1003 (4N2B)OptO Coupler

SPX3.1 Opto Coupler

IH 5045 CMOS Swilch DBST

UA 3045 Trans Array

TR 1402AUART

MK 1007 Dyn. Mem Shirt Reg..

5316TVCh Disp Circuit

6380A 8 Bit CPU

8700 CJ 8 Bil A/D

MM5280/VPD41WC2 107/7MS 4060/

4Kxl Dynamic 22 Pin RAM

6604/VPD 4 14/402 7/2660/MK 4096/

4Kx1 Dynamic 16P.n

7520/25

1488/1489

(M323K

1 953/1002/1 OC2/1 99

24 959 95795

2 95

69S3/100

3/1.00,4.50

C1372

1M5298-4A B .M 377M380

9 95

2 95

1 251 25

LM 387LM 4558HC4136RC4131COM 502/COM 5037

TYPE

VERBATIM DISKETTES

100% CERTIFIED ERROR-FREE!

3S riltCKS DOUBLE DENSITY SIKf.LE-SiOEO V.

PRICE BOX

$2995J29 95S2995

WD1941 995

COM 5016 16.95

INS 8250 15.95

KEYBOARD ENCODERS

AVS-2376 --- 1375

AY5-3600 - - 13 75

I US Ah*; etc525-16 <6 Mac Ham Metopous

a 10 I U TMCR ODUIIE 0ENSIT1 - SINGLE SIDtD

y, W'riUI HEINrOICEHENl DING

5'7D1 SOU Setlo'M tRS 80 dr. S32?S

57/-K- lOnmcHjiaNS Aou* el: 3225

■577-lf iBHnlc Ham Uctcws 3225a 40 MACKS OOOILE SIDED OOUIIE OINSITT 5'.

550-0' SCI SeclrjrerJ SA J50 MPt 52 J3995

550-10 10HoleH*d BAS' WANGCD J39.95

55016 l&HMEHarfl MciO* 13995a I ion*.. CENllflED DISKETTES

FOfflXMJI Soil Single Density 3740 S3350

F0800-.1? 3? Harfl Smqie Oi'nsity Slmg 33 50

FD802-UI Sol! OaiDie Oensny 3740 MIB

'DB50'Ot Soil Dwo«rS<M OouO*Dflnsty 3740 49B0VOLUME DEALER PRICING AVAILABLE

WE ALSO STOCK DYSAN-CALL

FLOPPY DISK I/O

1771-01 8"i Minifloppy1781 Dual Floppy1791-01 Dual Floppy179l-02Dual Floppy1793 DD. DS Floppy . .!797DD.DSFioppy .1691 Data Separator2l43ClockGen. . . .

24 95299536 95

FLOPPY CHIP SET

$79.95/set

A/D CONVERTERS

il Binarybit Binaryit TS

135022.0013.507 2513 953955 955 959 95995

8700 8 b

8701 It8703 8

9400 Voil lo Freg Con*8750 3'i Dnjil BCD1408L6 6 bit1408L8 8 HitDACOI D lo ADACOBDAC 100

TV CHIPS/SOUND

AY38500-1 6 Games B/W 4.95

AY38515 Color Convener 2 95

AY38603-1 RoadraceGame 8 95

AY38606-1 Wipeout Game 9 50

AY38607I Shooting Gallery 8 95

AY38910 Sound Generator 12.95SN7647 7 Tl Sound Generator 3 95

MM5320'21 TV Synch Gen 995

MM5369 Prescaler 3 95

LM18Q9 RF Modulnlor 3 95

MMS7100 NSC Color TV 6 95

MM57104 Clock Gen 3.75

M&R Modulator 2995

WAVEFORM GEN.

8038 Function Gen. . 4.50

MC4024VCO 295

LM566 VCO 1 95

XR2206 Function Generator . 5 25

SHIFT REGISTERS

2504V2507V2517V2524V252525272528252925333347

1.491.49

595

MM500H 50

MM5056N 2 95MMS060N 2 952510A 1 95

2847

3341

4.95

17 953357 6 959403 24 959406 995

CTS DIPSWITCHES

CTS206-2 1 75 CTS206-7 1 75

CTS206-4 1 75 CTS206-8 1 95

CTS206-5 I 75 CTS206-9 195

CTS206-6 1 75 CTS206-I0 195

CONNECTORS (GOLD)

Sui vWHood, Sale

22/4-1 W/W. S/T.HIM43/86 W/W. S/T. MOT50/1 CO S-100 Connector *50/100 S-100 Connector <

S-100 Sounii Board

8O80ACPU

32K Sialic RAM (21 I

8KEo'Om(2708)

2708/2716 Eprom

ACPPiotoBo"

Veclor 8800 Prol

it MB

S34.9534.9539.9524.9534.9522 95222029.9518.95

ACP Extender w/Conn„13SIOI Mo1herBoard|WMC)32 959 Slot Motrifi'BoardfWMCI 29 958 Slol Moihpr (Expandable) .34 95Floppy PCB (B- SHUGAflT* 3995

S100 (AY5-89101 Sound Bd 34.95Apple Sound Bd 24 95

..PRINTERS

EPSON

Centronics 739 ....

Vista V300t25cps

V-300/45cps .

Malibu 165

Anatfox 9500/9501 .Base II800 MST . .

799 00

1495.001795.001995.001450 00549.00

TERMINALS

TELEVIDEO

912C S799

920C S849

950C $995

AddSViewpoml . $599

AmpexDialonSO S1025

SoroclQ120 . . S699

IQ135 S899

IQ140 1149.00

^asAwrvo

(I MONITORS

Eajj^pafl VM4509 9'BW

VSSSr Sale Pnco 159.95

DM5012 12 "B/W 239.00

DM5112 12'Green 249.00

DM6013 13' Color 415.00

NEC Green 259.00

AMDEKfLEEDEX Video 100149.00AMDEK/LEEDex 13" Color399.00AMKEK/LEEDEX 12' Green 179.00

TERMS: UN cneck M/C VISA.AMEX CB. or COD COD requires25°6 deposit Charge Oroers pleaseinclude expiralion dale Foreign payU S Funds Order by phone, mail orTWX MINIMUM S1000 Please m-

SHIPPING USA add S2 00 tor l.rsl2 lbs For surface add 30e lor addi-nona' lbs For air add 70C lor addi-tional lbs FOREIGN Add 10% sh.p-O'"0 and nandlmg COD's $1 85 extraesponsible (or typos Some

ilems subiect to precious metal ad<Retail pricing may vary from NOrder We reserve the righi (o sisiilute manufacture'

RETAIL STORES OPEN MON-SAT

J '. JJV'ftiiiVfi irrr^yri

P.O. Box 17329 Irvine, Calif. 92713

Direct Order Lines: (714) 558-8813

(800) 854-8230 or (800) 854-8241

Circle 8 on inquiry card.

FOR INTERNATIONAL ORDERS'.1310 E. Edlnger (714) 953-06U4Santa Ana, CA92705 TWX:910-b95-1565

CaUFornja DiqiTAl

Post Office Box 3097 B • Torrance, California 90503

FREE PLASTIC LIBRARY CASE INCLUDED WITH THEPURCHASE OF EVERY BOX OF DISKETTES

fate labeled for California Digital by one ofmoat respected producers of magnetic media.| Each diskette is certified double density at 40

:ka. To Insure extended media life each dis-k is manufactured with a reinforced hub-hole,of course, a plastic library case is includedi every box of diskettes. MMD-CD5I01K10)nac specify computer or required sectors.

mm^m* box

Ten boxes $22.75

One hundred boxes $21.50

MINIUlSKinI Memo

Box lOboxei

h 74-KonioKie) s:u.oo 522.01

EIGHT INCH Scotch bo* 10 bx

Single slde/suiRle den. 740-0 $35. S33.Single sid<-/doublc den. 741-0 45. 43.Single stdo/32 sector 740-33 35. 33.Double side/ double D. 743-0 65. 59.

Dyson box 10 bx. MRX box 10 bx3740/1 $49. 547. 3060 $ 5. S-.3.3740/ld 75. 73. 3000 37. 35,

na! 3115 -19. 45^

SCOTCH brand head cleaning kit. S24.95

MMA-CK15HB) please specifv 5 1/4 6" *

Prices available on request for: tape, car

ridges, rilskpacks, volutnn diskettes.

MEMORY

TRS-80 «APPLE II

16k memory (8)4116's

Factory prime. Unconditionallyguarenteed for one full year.Add $3.00 for TRS-80 jumpersand instructions.

DYNAMIC

100+ 1K+

4113- 200ns4116 150ns4164 64K

3.25 3.00 2.75 2.50

3.75 3.50 3.25 3.00

49.50 45.00

STATIC

21L02 450ns.

21L02 250ns

2114L4 450ns

2114L3 300ns

4044-4 450ns

4044-2 250ns

5257-3 300ns

1.19

1. 493.954. 254.955.504.47

1.051.452.953. 754.504.954.25

1.392.75

3. 004.25

4. 504.05

EPROM

2708 450ns2718 5V.2716 Iri-volt2732 Intel2532 TI2764

4.957.959.9519.0021.50

9.0017.5019. 00

3.75

5.00

8.25

16.00

2.502.754.004.353.75

3. 254.507.50

direct connect

Your Choice

MODEM $169

Le, Direct!)Stelephora fine. No neeIOU-103LP 2 pounds

UDS 103J/LP AUTO ANSWER $213

tio

26 MegabyteHard Disk Drive

from

George Morrow's

Thinker Toys

s3495

Disc Jockey 20 conirolltDisk Jockey I Con;rDl!eiM'.'S hard diek Comrolit-Siutehboard Interface

M-10 Ten Megabyte nM

MEMOREX $

8"DISKETTES

25

The new L1SH timer nimi your home junl like clockwork. Turns on lamps andappliances while your awiiy from home. Completely compatible with your ex-isting System X-10 duvlces.

B5R Timer eight channel $65.00 Appliance Module 500 W. $13.95

.Master control console 34.95 Lnmp Module 300 Watts 13.05

Ultrasonic Controller 1U.95 NEW full control wall switch 14.50

S-100 Mother Board $35

QuietSuss

8803-1818 slotIMSAI

SWITCHES

CONNECTORS

S-100 .125" centersImsal solder .250" roImsai wire wrap ITUSullinu Hi-Hel. . 250" 4.SO 4.00

Sulllns Hi-RBI. W/W 5.35 4.90

Sullins/Altair . 140" 4.05 4.50

.156' Centers (standard)22/44 Kim Evelet 2.50 2.15

36/72 Digital Group S/T 5.35 5.5036/72 Digital Group WAV C.60 6.15*- 8.60 8.15

It.TEGKATEl) C1HCUIT SOCKETS

■oflle Wire Wrap

DA15P maleDA15S femaleDA hood 2/P

3.35

1.60

2.153.101.35

IJB251' maleUB25S femaleUB hood 2/P

3.503.351.35

2.393.15

1.15

UC37P male

DC.17S femaleDC hood 2/P

4.206.00

4.005.75

UD50P maleDD50S femaleUlJftO hood 2/P

5.50

y.40

2.60

5.108.G0

2.40

EUISBON CABLE CONNECTOUS17/34 5" disk 4.05 4.15 3.9520/40 THS-80 5.65 5.05 4.70

All merchandise sold by California Digital is premium gralipping: First five pounds $2.00; each additional add $.401 i orders 10% shipping. Excess will be refunded,lia residents add (i% sales tax. COD's discouraged

id i

uptimes with a Sire

Warehouse: ir>G08 Ingh

litors by appointmen

S-100 MAINFRAME

Mainframe includes 117/230 volt power supply and your choice of a

six or twelve slot motherboard.

Six slot enclosure is supplied with mounting provisions for one 5 1j

floppy disk or Winchester drive.

AC receptacle is provided for terminal or other ;ieeossory. Chass

has been punched to accept six assorted computer connectors.

Shipping weight 37 lbs. ENM-CD1 S265.00

=3. Shugart Associates

801/ R Disk Drive

15 lbs

Shu sari 801/H with CP206 power supply, muf:

plete in dual enclosure with all the H«BMIrJ

Document at Urn Included. 36 pounds. MSD- 18

Same as above but with two Shugart 801R disk drives.

50 pounds. MSD-2B01

Disk drive cable. 6 reel 50 conductor with edge card c<

at both ends. WCA-650S $25.00

Exporl Disk drives. 220V, 50MHz add $50,00 per disk

haust fan, wm-

!9slng cable* */95

♦1195

SHUGART801R

$

Qume Double SiHedB 1i«l< Drive '575

■W'

NEW

from

Shugart

Technology

m

MegabyteHard Disk Drive

Packaged in the same physical size as the industry stan-dard 5 1/4" minifloppy disk drive. The micro-Winches-ter stores thirty times as much data (6.38 megabytesunformatted), accesses data twice as fast (170 milli-seconds) and transfers data twenty times faster (5.0megabits per second. )

The ST506 is factory sealed to protect the media fromenvironmental contaminates. Requires only IDC voltage.Dual California Digital 5 1/4" enclosure. fc* C AASTI30G drive and power supply. f *9vll

Shugart Associates SA400 removablemedia disk drive for above package, add:S-100 & Apple controller scheduled forspring release.

»300

DATA INPUTTERMINAL

ind flbci-Kliiaa i-ncloiurc

t keyhuaril. Thirty dinplay l.ur.p»

ur Inch Unil npej.krr jchm,»U-Ji;ts

endlnK problems,

with a Utile Imagination, BM he MgEnMf

□ S-100 computer imrf tUtO dlsplav

o Rockwell Al-M-GS intcro/compulcr.

liable for

I condilion. Original acquisition over J700. 22 lbn.

Regulated

Power Supply

5 VOLT 5AMP

$U?5

■■..-I- supplv

Circle 51 on inquiry card.

TOLL FREE ORDER LINE

800)421-5041

TECHNICAL & CALIFORNIA

213679-9001

TWX 910 325-6212

CaHFornia DiqiTAl

Post Office Box 3097 B • Torrance. California 90503

I

Enclosure for Two 8''

Disk Drives and12 Slot Motherboard

$

. designed for c

e fleet i\

Modular in concept.

system integration. Buy as much as vou require.The basic enclosure is engineered from weldedW structural steel, RF line filter insures thai the

enclosure conforms to the Federal Communication Commis-sion RFI requirements. Two exhaust Tans provide maximun airflow across print-ed circuit cards. The enclosure has mounting provisions for two 8" Qume for Shugart disk drives.ind a 10 megabyte Winchester drive. The basic package is supplied with two AC accessory receptacles andall AC and DC power cables. Rear panel has been machined to accept nine assorted computer connectors.Shippinc weight 30 lbs. ENM-2D $375.00

supports two 0" disk drives and 12 slot motherboard.

POWi:R SUPPLY niounShipping watght IS lbs.

MOnil-JUBOAHD with noise canceling basket-weave ground plnnu. Complete with twelve gold S-100 edgeconnectors and curd cage. Shipping weight 3 lbs. BDB-MTIU2C JD9.00

World's Beat Selling Printer

EPSOMX 80

Immediate Delivery

Only $

475

Paper Tiger

560Gs1350

rYECSpinwriter551DP/S

I'ti- word proccsmnR (polity Spinwrit.?r prims at speeds upio

iclcri pet second. Ph« Model ."."iifii'/s is supplied witli boil. [<««•«<

ind us-:::':: aortal Interfticinj. Uso included is ilte tracior feud much

inlitu, alonj; Willi print tlitnMlle ,.id riyi.on. PRN-5ol0FS 71) U.S.

^•vhoartUKSH) M.,rl.-1 o20l'/S available S2U05. PRN-iiWe PS 7fi His.

PRINTRONIX

P-300 $4500P-600 *6150

PRINTERS

Epsoi

EpaoiAn adAnadiAn actIDS FIDS '1

MX80 PREMX80MX80FT PBEMXS0FNLX100 PREMX100x D500 PSA9500x 9501 PRAS501m ISO PRA150PBO480GPRG560GPRD63GPRU1G50PRD10-10PRD180PBP300PRPGOO

■ Tgr.

j u:io

i 1BS0

3 lfi-10

NEC/Sellum 1

PRHSSlOpa

2fi'J5

NEC/Sin 1GK

PRN55IGps

2795

TEC/Slarwril.

PRV300

1395

Okidata 80

probo

419

Okidata 82

PROB2

819

Okidata S3

PROfKt

895

Teletype 4UK

PTT4320K

1095

Texas Ins.MO

PRT810B

1450

Tex. Ins 810C

PRT810C

1795

Centronics 730

PRC730P

529

Centronics 737

PRC737P

695

Centronics 739

PRC739P

795

Centrnx 704-9

PRC70-1-9

1495

Cenirnx.704-11

PRC704-11

15G9

SYSTEMS

A m\?M

48K MEMORY

1170

2650

WKp% HEWLETTWf/iM PACKARD

HP85

ll...w/P.ick 85 SYSIIPS5 2650

Hew/Pack 03 SYSHP83 1895

Altos AC58000 SV5ACS8000 4795Osborne 1 SYSOBI 1795

Commodore SYSC8032 1495Commodore SYSC8096 1795

3upt»rbraia84QSYSSB64Q $3350

Superbrain64USYS.SB64D 2850

Northstard4Q SYSNG4Q 3295

Northstar G4D SYSNG4D 2895

NEC/PCBOOO SYSPC8000 call

Apple II Plus SYSAP 1170

VISA

=== = 3101

: ==== Display'=T= Terminal

IBM Direct Price '129.California Digital

$1195

discountprice

AMPEX

DIALOGUE 80CRT TERMINAL

J995

: Ampex Corporation. The DUlojUO III) natural removable keyboardihle two pages (four optional! du;tl program keys, half intensity protectedileitis and status line. Transmits rlat.i either block, line or character mode.Excellent value. VDT-DB0 shipping 47 lbs.

VIDEO TERMINALS

ADDS Regent 25 numeric cluster VDT-R25 $850

ADDS Regent 30 25th status line VDT-R30 950

ADDS Regent 40 limited graphics VDT-R40 1195

ADDS Regent 60 Block mode VDT-R60 1495

Ampex Dialouge 80 two page.detatch VDT-D80 995

Digital Equipment VT-100 VDT-V100 1595

Digital Equipment VT-132 VDT-V132 1895

Direct VP-800A emulator VDT-P800 call

Hazeltine 1410 VDT-

Hazeltine 1420 VDT-

Hazeltine 1500 VDT-

Hazeltine 1510 VDT-

Hazeltine 1520 VDT-

Hewlett Packard 2621A VDT-

Hewlett Packard 2621P VDT-

IBM 3101-10 character mode green VDT-

IB.M 3101-20 block mode VDT-

Lear Seigler 3A upper case only VDT-

Lear Seigler AD.M5 VDT-L5 945

Lear Seigler ADIU31 VDT-L31 1385

Lear Seigler ADM42 VDT-L42 1995

Soroc IQ 120 VDT-Q120 675

Soroc IQ 135 NEW VDT-Q135 850

Soroc IQ 140 detatchable keyboard VDT-Q140 1150

Televideo 912C VDT-T912 665

Televideo 920C VDT-T920 745

Televideo 950C detatchable keybd. VDT-T950 985

Zenith Z-19 VDT-Z-19 735

H1410 750H1420 795HI 500 850H1510 1025H1520 1225HP21AHP21P3101 119531012 1395L3A 850

VIDEO MONITORS

BMC ECQ12C 18MHz

P-31 grn phosphor $259

Leedex/Arndek 12"100 129

Leedex 100 green 169

Leedex 100-80 197

Hitachi color 13" 389

Zenith color 13" 379

NEC green phosphor 219Panasonic color 10"

Sanyo 9" BW 149

Sanyo 12" green phos. 235

Sanyo 15" BW 259

Sanyo 13" color 419

Shipping: First five pounds $2.00; each additional add $,4torders 10% shipping. Excess will be refunded.iiu residents add 6% sales tax. COIJ's discouragetended to state supported educational ins

mmmm.

Wa

(itors by appointment.

Correspondence quality printing.

A lot ol printers costing a lot more can't touch the MX-fSTsperformance. It gives you a choice of 40, 81). 66 or 132 col-umns of printing in js many as four distinct printing densitymodes, a total of twelve different combinations which canaccommodate nearly any printing requirement.

Bidirectional printing. Logical seeking Iof shortest linos. HO CPS. 64 graphics characters. Formshandling. The list of standard features goes on and on. Thefile I is thai there are few printers that can compete with theMX-80.il ANY price. And none—ZERO —in its extraordi-narily affordable price range.ABCDEFGHIJKLI1NDPDRSTUVWXYZABCDEFGH1J

Ti I iT.v.Wh*.". :WW? n fWrH I

ACCESSORIES FOR THE

COMPUTER

CALIFORNIA COMPUTER SYSTEMSArithmetic Procea.ior 7811 B/C $319

Asynchronous aerial Interface 7710 123

Centronics Interface card 7728 B5

12K PROM Module 7114 6B

Calender/CIock, Hal. back-up 7424 99

Parallel Interface 7720A 98

Procramable Timer 7740A 99

Analog/Digital converter 7470A 09MICROSOFT PRODUCTS

Apple to Z-80 CPU card 373D.C. HAYES PRODUCTS

Micromodem for Apple 31SCOMPUTER STOP PRODUCTS

Double Vision/B0 Column Video 25CINTERACTIVE STRUCTURES

16 Channel A/DcardAlO/2 275

MOUNTAIN COMPUTER PRODI'CIntro X-10 system for BSR {

Intro X-10 card onlv16 channel AD/DA 8 bitApple Clock hatterv back-upSupertalker SD200ROM Plus with filterROM Writer/ProgrammerAPPLE BRAND PRODUCTSApple Language cardFloppy disk with controllerFloppy disk without controllerApple parallel interfaceSSM MICROCOMPUTERDual serial parallel Interface AIOSORRENTO VALLEY ASSOCIATESB" floppy controller (Pascal)

S-100 BOARDS

Assembled • Tested • Burned-in

CPU BOARDS

Calif. Computer 2

J10A

/.-no

dma. vm*

lilJC

c:;iiio s:

UdJIioui Z-80 24 t

l, 4.\illz

BUG

GZ ao L

Godtxxtt uoii.yijoHii dual 1

BDC

(J88 :

Measurement Syst

emu Z

-no

4 eerial 2 parallel r

al Ultra

clock, H vector

BDC

MX HO L

SI) Svsu-n>s sue-:

JO 7.

HO

with serial 4 p

Mill.'

I/O pons

BDC

SBC2

Teletelt l-UC-I a

nste

CPU A Floppy disk ct

it roller

plus I/O

BDC

FDCl G

MAINFRAMES

Cal«. Computur 2

200A

12 slot K

ENM

-C2200 ;

TEI 12 yli.t l.ilil.:

ENAI

-T12

TBI 22 slot table

ENM

-T22 1

Godbout ni.iiufrii'.

ENM

-UM1-

UEft

ORY HOARDS

Calif.

dya.Clif.

mputer 206.'iA G IKi n tmorv BDM-CSOSif

mpUtBT 2010 18K

men.orv HDM-C201ISmputer 2032 32Kmemory BUM-C3032law 17 S4K static■v IS bit uiiM-an

1-LOPPY DISK CONTROLLERCalif. Computer 2422A with2.2 CP.M BDF-C2422

(jodbout "Disk (Ate" features thNEC 765 controller. DMAarbitration BDl -GDI

Meas

I Syst

765

recovery BD1--MF

SD Svstems Veraafloppy II

douhle densitv BDl- -VI-'.'.Turbell IJ/D BOF-TF!

Morrow Deaigri Disk Jockey 1

sififile density HDl'-DJl

■ ai.lv.- >!..-.

sum i

< Jocke'

BDl'-DJa

II

INTERFACE BOARDSCalif. Con^puter 2718 I/O

2 serial/2 par 1 BDT-C2TIH

Morrow Designs Switchboard

2 serial/4 pari BUT-MSBMorruw Designs Uultiboard

J B*triaI/3P. —- BDT-MMBliodhoul Enterf.tcer Che

2 serial/2 pari UD5-GtlGodboul Interfacer Two

1 serial/3par! BDS-CB3

SPECIALlnf BOARDSCJT Computet

ilock/

BUS-QCKwrap proio-BDS-AWW

rtL-c Elec. Ceneral Purposeproto board BDS-AOP

odhout Spectrum colorboard BDS-USC

. C. Hayes S-1CIU Micro-modem HDS-H.\I1

lulleo Products extender boan*. lopic prolji- kt HDS-Ml'ltl

Art

HDS- .H ■

Rotron Muffin Fan |*1477

$12.00 fe 10010.50 6 1000

115 VAC. 7 Watts WR2A1Factory fresh Muffin fansNOT pull-outs. EMF-4M

Circle 51 on inquiry card.

TOLL FREE ORDER LINE

800)421-5041

TECHNICAL & CALIFORNIA

(213)679-9001

TWX 910325-62121

7400

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74LS0O74LS0174LS0274 L 50374LS0474LS0574L.S0674LS0974LS1074LS1174LS1274LS1374LS1474LS1574LS2074LS2I74LS2274L.S2674LS2774LS2874LS3074LS3274LS3374LS3774LS3874LS4074LS4274LS4774LS4874LS4974LS5J74LS5474LS5574LS7374L57474LS7574LS7674LS7874LS8374LSS574LS8674LS90

745007450274S037450474 SOS74S0874 S0974S1074SU74 SIS7452074S2274S307453274S387454074S5174S6474S6574S7474S8674511274SJI374S114

SN7472NSN7473NSN7474N

SN747SNSN7476NSN7479NSN7480NSN7482NSN74B3NSN74B5NSN7466NSN7469NSN7490NSN7491NSN7492NSN7493NSN7494NSN7495NSN7496NSN7497N5N741QQNSN74104N5N74105N5N74107NSN 74109 NSN74116NSN74121NSN74122NSN74123NSN7412SNSN74126NSN74132NSN74136NSN74141NSN74142NSN74143NSN74144NSN7414SNSN74147NSN74I48NSN74150NSN741S1NSIM74152NSN74153NSN74154NSN74155N

3.25

3.493.49

W$

SN74156NSN74157NSN74160NSN74161NSN74162NSN74163NSN74164NSN 74165 NSN74166NSN74167N5N74170NSN74172NSN74173NSN74174N5N74175NSN74176N5N74177NSN74179NSN741S0N5N741B1NSN74182NSN741S4NSN741SSNSN74190NSN 74191NSN 74192 NSN74193N5N74194NSN74195NSN74196NSN74197NSN74198NSN74199N5 N 74221NSN742S1NSN74276NSN74279NSN74283NSN74284NSN74285NSN74365NSN74366NSN74367NSN74368NSN74390NSN74393N

74LS

74LS92

74LS9374LS9574LS9674LS10774LS10974LS11274 LSI 1374LS11474LS12274LSI2374L512S74LS12674LS13274LS13374LS13674LS13874LS13974LS15174LS15374LS15474L515574LS1S674LS15774LS1S874LS16074LS16174LS16274LS16374LS16474LS16S74LS16874 LS16974LS17074LS17374 LSI 7474LS17S74LS18174LS19074LS191

1.15

1.151.151.191.191.95

74LS19274LS19374LS19474LS19574LS19774 L 522174LS24074LS24174LS24274LS24374LS24474LS24574LS24774 LS24874LS24974LS25174LS2S374LS2S774LS25874LS26074LS26674LS27374LS27974LS28374LS29074 LS29374LS29874LS35274LS35374LS36S74LS3G674 L 536774LS36874L537374LS37474LS37S74LS38674LS39374LS39974L567081L 59581LS97

74S

74 S12474 S13374 S13474S13S74S13674S13874S13974S14074S15174S15374S157745158745160

745174

74517574518874S19474519574S19674S24074S24174S242

1.951.952.952.95

74S24374S24474S2S174S25374S25774525874526074S2B074S2B7J4S2BB74S37374S37474S38774S47]74S47274S47374547474S47S74557074SS7174557274S57374S94074S941

1.151.151.151.151.191.19

2.492.492.49

2.753.493.492.9519.9510.9510.9512.9512.955.955.959.959.95

4-Digit 16 SegmentAlphanumeric Intelligent

Display withMemory, Recorder, Driver

End-siackoble, 4-choracier package. High con-trast, IGOinii high, magnified monolithiccharacter*. W Chnnictor ASCII formal. Built-inmemory, decoder, multiplexer and drivers. Directaccess to each digit independently and asyn-chronously. Five volt logic, TTL compatible. Fivavolt power supply only. Independent cursor func-tion. Site: 1"L x 1-3H6-H x .225'D.DL-1418 Alphanumeric Display $19.95 M,

ZJ

10-SegmentBargraph Displays

(with On-Board Driver IC-Chip)

Size: 2"L X 7/8"H x 3/lG"D

tsat or dot display mode externally selectable by user.Packages era end-stackablo for expended displays. Can becascaded to 10 arrays 1100 bargraph elements!. LEO currentprogrammable from 2mA lo 30mA. Stable internal voltagereference for full scale analog inputs from 1.2 to 12V. Each LEDoutput of driver IC with external access. Size: 2"x7/8"x3/1S".NSM3914 Linear Function [10 barm red) *6.96

NSM39146 Linear Function [Bbara graen/4 red) 8.86

NSM3916 Logarithmic Function (10 bars red) 5.96

NSM3916B Logarithmic Func. (8 grn./2 yell./ 2 rd.l 8.86NSM3918 VUMeter Function M0 ben red) 5.96

NSM391B8 VU-MeierFunc. (8grn./2yelf./2rd.l 6.96

DISCRETE LEDS

XC556R .200" redXC556G .200" greenXC556Y .200" yellow 4/S1

XCS56C .200" clear

XC22R .200" red

XC22G .200" green

XC22Y .200" yellov

MV10FJ .170" red

4/ii

5/H4/J14/J1

4/S1

MV50 .085" red

XC209R .125" red

XC209G .125" green

XC209V .125" yellow

XC526R .IBS" red

XC526G .185" green

XCS26Y .185" yellow

XCS26C ,185" clear

C.A. — Common AnodeD.D. — Double Digit

■;200(TI^)Rea7Gr c c i

Diffused Bi-Calor LEDPart No. 1-99 100+

^, ^MmL

RL-2 . . $.39e-;i.or 3/S1.00

TypeMAN 1

MAN 2MAN 3MAN 52MAN 54MAN 71MAN 72MAN 74MAN B2MAN 84MAN 3520MAN 3630MAN 3640MAN 4610MAN 6610MAN 6630MAN 6640MAN 6650MAN 6660MAN 6710MAN 6740MAN 6750DLO304DLO307DLG500

PolarityC.A.—red

5x7 D.M.—redC.C.-redC.A.—greenC.C.—greenC.A.—redC.A.—redC.C.—redC.A.—yellowC.C.—yellowC.A.—orangeC.A.—orange ± 1C.C.—orangeC.A.—orangeC.A.—orange—DD .C.A.—orange ± 1C.C.—orange—DD .C.C.—orange * 1C.A.—orangeC.A.—red—DDC.C.-red—DDC.C.-red ± 1C.C.—orangeC.A.—orangeC.C.— green

DISPLAY LEDS

t Price

'0 2.95

Type

DLG507

DL704

DL707

DL728

DL741

DL747

DL7S0

DLOS47

DLO8S0

OL33S

FND358

FND357

FND500

FND507

HOSP-3401

HOSP34Q3 C.C,

HDSP-3406 C.C. red

5082-7751

C.C. -

RHDPolarityC.A.—greenC.C.-redC.A.-redC.C.-redC.A.—redC.A.—redC.C.-redC.A,—orangeC.C—orangeC.C.-redC.C. ± 1C.C.

C.C. (FND503)C.A. {FNDS10)C.A.—red

;ommon CathodeRight Hand DecimalHt Price

:1

5082-7760

5082-7300

5082-7302

5082-7340

4N28

LtT-1

MOC3010

.430

C.A..R.H.D.— redC.C.R.H.D.—red .430

4x7Numeric (RHD).6004x7Numeric (LHD).6004x7Hxdcl.(Q-9/A-F) .600Photo XslstorOpto-lsol.Photo Xsistor Opto-lsol.Optically Isol.TriacDrlvt

1.2S1.25

22.0022.0022.50

SOCKETS

^^^■fc. RECEPTACLES

Test if*^ Sockets

ZERO INSERTION FORCE

Part No. Pins Price

214-3339 14 pin 5.95216-3340 16 pin 6.49218-3341 18 pin 7.95220-3342 20 pin 8.95

* Nickel Boron Plating

* G.F.PSF Plastic Body

* For testing IC'iPartNo. Pins Price

222-3343 22 pin 9.95224-3344 24 pin 9.75228-3345 28 pin 11.95240-3346 40 pin 12.95

LOW PROFILE(TIN) SOCKETS

8 pin LP14 pin LP

!6 pin LP18 pin LP20 pin LP22 pin LP24 pin LP28 pin LP36 Pin LP40 pin LP

SOLDERTAIL <GOLD)STANDARD

8 pin SG14 pin SG16 pin SG18 Pin SG24 pin SG28 pin SG36 pin SG40 pin SG

* Nickel Boron Plating

* G.F. PSF Plastic Body

* Wire Wrap ContactsPartNo. Pins Price

214-3592 14 pin 9.75

216-3S93 16 pin 9.9S

218-3594 18 pin 10.95

220^595 20 pin 11.95

PartNo. Pins Price

222-3596 22 pin 12.95224-3597 24 pin 12.75228-3598 28 pin 13.95240-3599 40 pin 15.95

tipi

hit f it

SOLDERTAIL

STANDARD (TIN)

14 pin ST

16 pin ST18 pin ST24 pin ST28 pin ST36 pin ST40 Pin ST

1.391.59

1.261.45

WIRE WRAP SOCKETS(GOLD) LEVEL #3

1-24 25-49 50-100

Part No. Function

7045IPI CMOS Precision Timer

7045EV/Kit* Stopwatch Chip, XTL

7106CPL 3Vi Digit A/D (LCD Drive)

7106EV/Kit* IC. Circuit Board, Display

7107CPL 3V* Digit A/D (LED Drive)

7107EV/KU* IC, Circuit Board, Display

7116CPL 3vz Digit A/D LCD Dis. HLD.

7117CPL 3Vi Digit A/D LED DlS. HLD.

7201IDR Low Battery Volt Indicator

7205IPG CMOS LED Stopwatch/Timer

7205EV/Kit* Stopwatch Chip, XTL

7206CJPE Tone Generator

7206CEV/KH- Tone Generator Chip, XTL

7207AIPD Oscillator Controller

7207AEV/KU* Freq. Counter Chip, XTL

720BIPI Seven Decade Counter

7209IPA Clock Generator

721SIPG 4 Func. CMOS Stopwatch CKT

7215EV/KU* 4 Func. Stopwatch Chip, XTL

7216AIJI 8-Dlglt Univ. Counter C.A.

7216CIJI 8-DIgit Freq. Counter C.A.

7216DIPI 8-Oigit Freq. Counter C.C.

7217IJI 4-Diglt LED Up/Down Counter

7218CUI 8-Dlglt Univ. LED Drive

7224IPL LCD iVt Digit Up Counter DRI

7226AIJL 8-Dlgit Univ. Counter

7226AEV/Kif 5 Function Counter Chip, XTL

7240IJE CMOS Bin Prog. Timer/Counter

7242IJA CMOS Dlvide-oy-256 RC Timer

72S0IJE CMOS BCD Prog. Timer/Counte

7260IJE CMOS BCD Prog. Timer/Counte

75S5IPA CMOS 555 Timer (8 pin)

7SS6IPD CMOS 556 Timer (14 pin)

76UBCPA CMOS Op Amp Comparator 5MV 2.25

7612BCPA CMOS Op Amp Ext. Cmvr. 5MV 2.95

7621BCPA CMOS Dual Op Amp Comp. SMV 3.95

7631CCPE CMOS Trl Op Amp Comp. 10MV 5.35

7641CCPD CMOS Quad Op Amp Comp. 10MV 7.50

7642CCPD CMOS Quad Op Amp Comp. 10MV 7.30

7660CPA Voltage Converter 2.95

8038CCPD Waveform Generator 4.95

8048CCPE Monolithic Logarithmic Amp 21.60

BQ69CCQ 50ppm Band-GAP Volt Ref. Diode 2.S0

82UCPA Volt Ref/lndlcator 2.95

B212CPA Volt Ref/lndicator

Price

14.9524.9516.9534.9515.9529.9518.9517.95

2.2512.9519.95

5.1512.95

6.5013.9517.95

3.9513.9519.9532.0026.9521.9512.9510.9511.2531.9574.95

4.95

2.05■ 6.00- S.25

1.4S

2.20

2.95

74C0074C0274C0474C0874C1074C1474C2074C3074C4274C4874C7374C7474C8S74C8674C8974C9074C93

74C9S

74 C10774C15174C15474 C15774 C16074C16174 C16274 C16374C16474C17374C17474C17574 C19274CI9374C19S

74C

74C22174C24074C24474C37374C37474C90174C90374C91174C91274C91S74C91774C92274C92374C92574C92680C9580C97

1.952.252.252.49

2.59

10.95

5.495.75

LH0002CN

LPvllOCLH

LM11CLH

LH0070-OH

TL071CP

TL072CP

TL074CN

LH0O82CD

TL082CP

TL084CN

LH0094CD

LM300H

LM301CN

LM302H

LM304H

LM305H

LM307CN

LM308CN

LM309H

LM309K

LM310CN

LM311/CN

LM312H

LM317MP

LM317T

LM317K

LM31BCN

LM319N

LM320K-5

LM320K-12

LM320K-15

LM320T-5

LM320T-12

LM320T-15

LM323K

LM324N

LM329DZ

LM331N

LM3342

LM335Z

LM3362

LM337T

LM337MP

LM338K

LM339N

LM340K-5

LM340K-12

LM340K-15

35.601.192.19

36.80.99

LINEAR

LM340T-5 1.25

LM340T-12 1.25

LM340T-15 1.25LM341P-5 .75

LM341P-12 .75LM341P-15 .75LM342P-5 .69

LM342P-12 .69LM342P-15 .69LM348NLM350K

LF351N

LF353N

LF355N

LF356N

LM353N

LM359N

LM370N

LM373N

LM377N

LM380N

LM381N

LM382N

LM384N

LM386N-3

LM387N

LM389N

LM392N

LFJ9BN

LM399H

TL494CN

TL496CP

NE510A

NE529A

NE531H

NE536H

NE540H

NE544N

NE550A

NE555V

LMS56N

NE564N

LM565N

LM566CN

LM567V

NE570N

5.75.601.001.101.10

LM702H

LM703CN

LM709N

LM710N

LM711N

LM723N

LM733N

LM739N

LM741CN

MC1741SCG

LM747N

LM748N

LM1014N

LM1310N

LM1458CN

LM1488N

LM1489N

LM1496N

LM1556V

LM1800N

LM1871N

LM1872N

LM1877N-9

LM1889N

LM1896N

LM2002T

LM2877P

LM2878P

LM2896P-1

LM31B9N

LM3900N

LM3905CN

LM3909N

LM3914N

LM391SN

LM3916N

RC4136N

RC4151NB

RC4194TK

RC4195TK

LM4500A

ICL3038B

LM13080N

LM13600N

75138N

754 SON

75451CN

75492

CA3010HCA3013HCA3023H

CA3035HCA3039HCA3046NCA30S9N

1.35

1.303.25

CA-LINEAR

CA3060NCA3O80HCA30B1NCA3082NCA3083NCA30B6N

CA3089NCA3096NCA3130HCA3140HCA3160HCA3401NCA3600N

1/4 WATT RESISTOR ASSORTMENTS -5%

10 Ohm 12 Ohrr5ea. 27 Chm 33 Olm

15 Ohm 18 Ohrr39 Ohm 47 Ohn

22 0hrT56 Ohrr

50 pes. $1.95

CAPACITOR CORNER

50 VOLT CERAMIC DISC CAPACITORS

CD4000CD4001CD4002CD4006CD4007CD4009CD4010CD4011CD40I2CD4013CD4014CD4015CD4016CD4017CD401BCD4019CD4020CO4021CD4022CD4023CD4024CD4025CD4026CD4027CD4028CD4029CD4030CD4034CD4035CD4O40

CD-CMOS

CD4043CD4042CD4043CD4Q44CD4046CD4047CD4048CD4049CD4O50CD4051CD40S2CD40S3CD4056CD4059CD4050CD4066CD4068CD4069CD4070CD4071C CM 072CD4073CD4075CD4076CD4078CD4081CD4082CD4093

CD 4098CD4506CD4507CD4508CD4510CD451)CD4512CD4S14CD4515CD4516CD4518CD4519CD4520CD4526CD4528CD4529CD4543CD4S62CD4S66CD4583CD4584CD4723CD4724MC14409MC14410MC14411MC14412MC14419MC14433MC1453BMC14541

ASST. 2

5ea.

68 Ohm 82 Ohm 100 Ohn180 Ohm 220 Ohm 270 Ohn

l 120 Ohm 150 Ohm1330 Ohm 390 Ohm

50 pes.

$1.95

ASST. 3

5ea,

470 Ohm 560 Ohm6B0 Ohn1.2K 1.5K l.BK

i820 Ohm IK2.2K 2.7K

50pc5.

$1.95

Value l-g 10-99 100+

10 pf

22 pf

47 pf100 pf220 pf

■1/0 \-

.06

.05

Value.OOluF.004 7pF.QljiF-022m F.047uF■ IMF

1-9 10-99 100+

ASST. 4 Sag.ASST. 5 _ 5an.ASST. 6 5ea.

3.9 K10K

22 K

56K

4.7K 5.6K 6.8K

12K 15K 18K _

33K 39K 47K

82K 100K 120K

EOpcs. $1.9550pcs. $1.95

220K 270K 330K

560K 680K 820K

100 VOLT MYLAR FILM CAPACITORS

.OOlmf .12 .10 .07 | .022mf .13 .11 .08

.0022mi .12 .10 .07 .047mf .21 .17 .13

.0047mf .12 .10 .07 .lmf .27 .23 .17

.Olrni .12 .10 .07 1 .22m! .33 .27 .22

+20% DIPPED TANTALUMS (Solid) CAPACITORS

50pcs. $1.95

1.291.791.791.952.7911.952.792.49.751.951.9514.9514.9514.9511.95

ASST. 7 5ea.

1.2M3.3M

1.5M3.9M

2.2M5.6M

50pcs. $1.95

ASST. 8R

Includes Resistor Assts. 1-7 {350 pes.)

$10.95 ea.

S10.00 Min. Order - U.S. Funds OnlyCalif. Residents Add 6% Sales TaxPostage- Add 5% plus$1 Insurance

'N£\N

> 1982„^tcAf&SS*

lameco

ELECTRONICS

Spec Sheets - 254

Send 86ff Postage for your

FREE 1982 JAMECO CATALOG

PHONE

ORDERS

WELCOME

(415)592 8097

MAIL ORDER ELECTRONICS - WORLDWIDE

1355 SHOREWAY ROAD, BELMONT, CA 94002

PRICES SUBJECT TO CHANGE

.1/35V. 15/35V.22/35V. 33/35V.47/3SV.68/35V1.0/3SV

Axial

.47/50V

1.0/SOV

3.3/S0V

4.7/25V

10/25V

10/50V

22/2SV

22/50V

47/25V

47/SOV

100/25V

100/50V

220/25V

220/50V

470/25V

1000/16V

2200/16 V

.39

M

.29

1.5/3SV

34

.29

2.2/35V

M

.29

3.3/25V

M

.29

4.7/25V

34

.29

6.8/25V

34

.29

15/25V

34JM

.29ELEC

22/6VrROLYT

M*

3 500+

Radial

14

.10

-47/25V

lfi

.12

-47/50V

If.

.11

1.0/16V

IK

.11

1.0/25V

15

.11

1.0/50V

16

.12

4.7/16 V

Ih

.12

4.7/25V

?0

.18

4.7/50V

?1

.19

10/16 V

2ft

.23

10/25V

24

.22

10/50V

V

.34

47/SOV

14

.33

100/16V

4S

.41

100/2SV

4<l

.45

100/SOV

61

.61

220/16V

.79

.69

470/25V

.29

1.39 1.25 .95

1-99 100499 500+

.15 .13 .12

486 BYTE September 1981

Circle 180 on inquiry card.

/agSfSSSKjuctorClock Modules

12V DC

AUTOMOTIVE/

INSTRUMENT

CLOCK

APPLICATIONS:

• In-dash autoclocks

• After-market auto/RV clocks

• Aircraft-marine elks.

• 12VDC opar. Instru.

• Portable/batterypowered instrumnts.

Features:Bright 0.3" green display. Internal crystal time-base, i 0.5 sec./day accur. Auto.display brightness controllogic. Display color filterable to blue, blue-green, green &yellow. Complete-just add switches and lens.

MA1003 Module (3.05»lxi.75»hx.98"d» . $16.95

CLOCK MODULES

MA1023 .7" Red Digital LED Clock Module 8.95

MA1026 .7" D.g. LED Alarm Clock/Thermometer 18.95

MA5036 .3" Red Digital LED Clock/Timer 6.95

MA1002 ,5" Red Digital LED Clock & Xformer 9.95

MA1010 .8" Red Digital LED Clock 7.95

MA1032 CBA .5" Red Digital LCD Clock 17.95

MA1Q43 .7" Green Digital LED Clock 8.95

TRANSFORMERS

102-P20 Xformer forMA1023, 1043 & 5036 Mods. 3.49

102-P22 Xformer for MA1026 Clock Modules 3.49

102-P24 Xformer for MA1010 Clock Modules 3.49

8 OHM SPEAKER

2J4" - 8 Ohm - .25 watt

A0201$1.25 ea. 2/$1.95ea. 10/S7.95ea.

o

BATTERY HOLDER

•Holds 2 ea. C cells

• Aluminum Case

•5" leads H-801-159

$ .45 each 10/S3.95

BATTERYN HOLDER

■?> • Holds 4 ea. C cells

• Plastic case

• 9" leads$.49 ea 10/S4.25

EPROM Erasing Lamp

• Erases 2708, 2716, 1702A, 5203Q, 5204Q, etc.

• Erases up to 4 chips within 20 minutes.

• Maintains constant exposure distance of one inch.

■ Special conductive foam liner eliminates static build-up.

• Built-in safety lock to prevent UV exposure.

• Compact - only 7-5/8" x 2-7/8" x 2"

• Complete with hording tray for 4 chips.UVS-11EL Replacement Bulb $16.95

UVS-11E $79.95

JOYS

ICKS

; y

JS-5K 5K Linear Taper Pots $5.25

JS100K 100K Linear Taper Pots $4.95

JVC-40 40K (2) Video Controller in case . . . $4.95

6-DigitClock Kit

• Bright .300 hfc comm. iode display

• Uses MM5314 clock chir.

• Switches for hours, mirand hold modes

easily viewable to 7lated walnut case•115 VAC operation

• 12 or 24 hr. operation

JE701 $19.95

JE215 AdjustableDual Power Supply

General Description: The JE215 is a Dual PowerSupply with independent adjustable positive and nega-tive output voltages. A separate adjustment for eachof the supplies provides the user unlimited applicationsfor IC current voltage requirements. The supply canalso be used as a general all-purpose variable power

Supply. FEATURES:

• Adjustable regulated power supplies,

pos. and nag. 1.2VDC to 15VDC.■ • Power Output (each supply):

5VDC $ 500mA, 1 OVDC @ 750mA,

12VDC@ 500mA, and

15VDC@ 175mA.

Two, 3-torminal adj. IC regulators

■ Heats

i LED ■

ogule

JE215 Adj. Dual Power Supply Kit (as shown). . $24.95

(Pic

JE20Q Reg. Power Supply K

■ in construction to above). 5VDC, lamp) . . $14.95JE205 Adapter 3rd. (to JE200) i 5, ■ 9 & ±12V. $12.95JE210Var.Pwr. Sply. Kit, 5-15VDC,to1.5amp. $19.95

MICROPROCESSOR COMPONENTS

8080A/8080A SUPPORT DEVICES

DP821!

8-Blt Input/Output

DPB2H

Priority Interrupt Control

OPB216

BIDIretlloml Bui Drivar

DP8224

Clock Ganeratoi/Drluor

□ P8226

But Diluar

DP8Z28

Syitam Controllar/Bui Orlvsr

DPB233

INS82U

I/O Expander tor 48 Serial

iNsawi

Aiynchronoui Comm. Element

OP8251

Prog. Comm. I/O (USART)

DP«51

DPB2S5

Pros. Peripheral I/O (PPI)

DPS257

Plat. DMA Control

DP8259

OPS275

Prog. CRT Controller

DPB2I9

Prog. KeyEaard/Dlsplay Intarrice

Syitam Timing Elemanl

DPSX4

8-Hlt Bl-Dlrectlonil Receiver

OP8307

DP831C

Octal Latcnecl Peripheral Driver

DP8J11

Octal LatcheJ Peripheral Driver

6800/6800 SUPPORT DEVICES -

MC6800 MPU

MCGS0ZCP MPU with Clock ana RAM

128x8 Static RAM

(MC02OJ

MC6810API

MCGB21MC6S28

Priority Interrupt Cont1D24*B-Blt ROM (MCS8A30-S)

Synchronous Serial Data AdapterWOOddi Digital MODEM2W0OPI MooulatorQuad J-State Bui. Trans. (MCBT26)

-MICROPROCESSOR CHIPS

Z80 (7800 CPU (MKJ880N) (2MH;]

Z80A (780-]) CPU (MKMMN-J] |1MH:|

CDP1802 CPU

2650 MPU

IDM2901ADC CPU—4-Bil Slice (Com.Temp

MCS6502 MPU w/Clock (6SK Bytes Mi

INSS03SN-6 MPU-8-Blt [5MHz)

INSB0J9N-6 CPU-Sgl.CnipB-BIt [128oyte

INSSWON-8 CPU (X6 Bytei RAM)

INSS070N CPU-64 Bytes RAM

INS8073N CPU w/BasIc Micro Interprc

PB0BS CPU

-SHIFT REGISTERS-

MM510HMM1402NMMM13NMM50MM

MMWMNMM50MN25MV(M04A)

2S1BN

Dual 64-Bit Accu254-Bit Dynamic1024-Bll DynamicS00/S]2-Blt Dynar

K 33-Bit■I 132-B

Stat

SlI-BIt Dynen1024-Bit DynamicDual »0-Blt StaticDual 240-Bit StaticQuao 80-Bit StaticFllo (Dual 8QJ

-DATA ACQUISITION-

Touch Tone

LM30SAHLM334ZLM335ZLFJ66N

ADC08O4LCN B-BItDACOeOSLCNS-SIt

-DATA ACQUISITION (CONTINUED)-

ADCONSCCNADCD81ICCNOAC1000LCNDAC1008LCNDAC1020LCNDAC1Q22LCNOAC1222LCNC DM141N

B-BIt A/D Converter (B-Ch. HB-BIt A/D Converter (16-Ch. Fv10-Blt D/A Conv. Micro. Com;10-Bit D/A Conv. M Icro. Comi10-Blt D/A Converter (0.05% L10-Slt D/A Converter (0.20% L12-BltD/A Converter (0.20% L

256x4 5tatlc

Z£x' Static MOS

1024x4 Static 450ns

1024x4 Static 450ns Low Power

1024x4 Static 700ns

1024x4 Static 200ns Low Power

256x1 Static

< Dynar

c 250ns (MM5290N-4)

4164 64K Dynar

MM2I47J 4096x1 Fait JOns

5101 256x4 Static

MM5261 1024x1 Dynamic Fully Decoaed

MM5762 ?n.l Dynamic

MM5280/110J 4096x1 Dynamic

MM5290N-? (4!16| I6K Dynamic 150ns (UPD416C-3I

MM5298J-3A 8K Dyn. 200ni (lower 'a of MMS290J)

B2S2S 64 Bit RAM (16x4)

UPD414/MK4027 4K Dynamic 16-pln

TM54044-4JNL 4K Static

TMS4045 1024x4 Static

-PROMS/EPROMS-

2764 Q

5203

82S23 (745188)

B2S1JS

B2S123(74S28S)

82S1B5

- Over JO M

BK EPROM

16K EPROM (-5V, »5V, *12V)16K EPROM (Single + 5V)32K EPROM

BK EPROM (4S0ns) (Single 45V)64K EPROM2048 PROM

32KB PROM (Open Collector)4096 Bipolar PROM32xB Trl-State Bipolar PROMBK PROMire PROMS Listed In Our Catalog -

ROM'S

Ctlar

NMOS READ ONLY MEMORIES"

MCM66710P 128x9x7 ASCII Shittea w/Greek

MCM66740P 128x9x7 Math SymPol L Pictures

DS0025CN

OS0026CN

INS1771N-1

INS2G51N

MM5B167M

MM5B174N

COP402N

COP402MN

■ SPECIAL FUNCTION

Dual MOS Clock Driver (SMZ)Dual MOS Clock Driver (5MZ)Floppy Disc ControllerCommunication ChipMicroprocessor Real Time ClockMicroprocessor Compatible ClockMicrocontroller with 64-Dlglt RAMand Direct LED DriveMicrocontroller with 64-Dlglt RAMt. Direct LED Drive w/N Buss Int.32-Sag.VAC Fluor. Driver (ZO-pIn pkg.)

-TELEPHONE/KEYBOARD CHIPS"

AY- 5-2376

HD0165-5

74C922

T4C923

MM53190N

CMOS Clock GeneratorKayooard Encoder (8S keyi)Keyboard Encoder (16 keys)Keyboard Encoaer (16 keyt)Keyboard Encoder (20 keys)Puih Button Pulse Dialer96/144-Key Serial Keyboard E

ELECTRONIC TOY MOTORS

T,pc.l

TOnouE

ftSST

—

15 60

30

9.30Q

0 20

6.7BO

0 90

0.260

1.30

570

0.97

,9,3„7,?D■ x. MABUCHI RE280 $.99each

1.201 Length

.10/57.50. . .100/S50.00

GLOBALSPECIALTIES

EXPERIIHEDITORSOCKETS

Model

Langth

Width

Chann.

Terminal.

Strip)

P„»

EXP4B

6.0"

1.0"

n/a

n/a

4(160)

$ 4.75

EXP300

6.0"

2.1"

.3"

84(470)

2(80)

SI 2.08

EXP325

1.8"

3.6"

2.1"

2.1"

.3"

22(110)

2(20)

$ 3.S0

EXP350

.3"

46(230)

2(40)

$ E.75

EXP600

6.0"

2.4"

.6"

94(470)

2(80)

$14.78

EXP65Q

3.6"

2.4"

.6"

46(230)

2(40)

S 8.75

Quick TestSockets& Bus Strips

.351-9

.30362-81210-99

.25100

.391-9

.35473-862

10-99

.30

100

.451-9

.39468-82810-99

.35

100

.491-9

.45435-80210-99

.39100

POWER CORD SALE

>*

AC and DC Wall Transformers

QT-HI

6.5"

6.!"

MS $12.50

QTHB

B.S"

8.2"

20 S 2.00

QI-47S

B.I"

5.0M

S4 SI0.24

0T-47BQT-1BQTOIf

8J"

5.0"3.1"3l"

IE S 2.69

To' S B.EO12 $ 2.25

QT-llS

14"

2.I"

38 9 4.50

or us

QT-liQI-JS

$10.00 Min. Order - U.S. Funds OnlyCalif. Residents Add 6% Sales TaxPostage-Add 5%p1us$1 Insurance

ELECTRONICS

Spec Sheets - 254

Send 86tt Postage for your

FREE 1982 JAMECO CATALOG

PHONE

ORDERS

WELCOME

(415) 592-8097

MAIL ORDER ELECTRONICS - WORLDWIDE1355 SHOREWAY ROAD, BELMONT, CA 940029/8i PRICES SUBJECT TO CHANGE

Part No.

Input

Output

u« wilh clocks.Owtr uipplici orr type ul AC or

Price

AC 250 117V/60H; 12 VAC 250mA $3.95

AC 500 117V/60Hz 12 VAC 500mA $4.95

AC1000 117V/60Hz 12 VAC 1 amp $5.95

AC1700 117V/60HZ 9 VAC 1.7 amp $3.95

DV 9200 117V/60Hz 9 VDC 200mA $3.25

DC 900

120V/6QHZ

9 VDC 500mA $3.95

CONNECTORS

OB25P D-Subminiature Plug S2.9S

DB25S D-Subminiature Socket $3.50

D20418-2 Screw Lock Hdwr. (2) DB25S/P » .49

DB51226 Cover for DB2GP/S $1.75

22/44SE P.C. Edge (22/44 Pin) $2.95

UG88/U BNC Plug $1.79

UG89/U BNC Jack $3.79

UG175/U UHF Adapter $ .49

S0239 UHF Panel Recp $1.29

PL258 UHF Adapter $1.60

PL259 UHF Plug $1.60

UG260/U BNC Plug $1.79

UG1094/U BNC Bulkhead Recp $1.29

TRS-8016K Conversion Kit

Expand your 4K TRS-80 System to 16K.Kit comes complete with:

* 8 ea. MM5290 (UPD416/4116) 16K Dyn. Rams (" NS)

* Documentation for Conversion

TRS-16K2 -150NS $29.95

TRS-16K4 -250NS $24.95

JE610 ASCIIEncoded Keyboard Kit

The JE610 ASCII Keyboard Kit can be interfaced intomost any computer system. The kit comes completewith en Industrial grade keyboard switch assembly(62-keys), IC's, sockets, connector, electronic compo-nents and a double-sided printed wiring board. Thekeyboard assembly requires +5V @ 150mA end —12V0? 10 mA for operation. Features: 60 keys generate the126 characters, upper and lower case ASCII set. Fullybuffered. Two user-define keys provided for customapplications. Caps lock for upper-case-only alpha charac-ters. Utilizes a 2376 (40-pin) encoder read-only memorychip. Outputs directly compatible with TTL/DTL orMOS logic arrays. Easy interfacing with a 16-pin dip or18-pin edge connector. Size: 3'A"H x 14W"W x 8%"D

JE6107DTE-AK &!&',%??!£, ...$124.95

irC1n [/■.+ 62-Key Keyboard, PC Board, * -wn nt-JtO IU Kit & Components (no case) $ /y.y5

K62 62-Key Keyboard (Keyboard only) . . .$ 34.95

DTE-AK (case only — 3V*"Hxir'Wx8*."D)$ 49.95

JE212 - Negative 12VDC Adapter Board KitNEW!? for JE610 ASCII KEYBOARD KIT

Provides-12VDC from incomingSVDC . .$9.95

JE600Hexadecimal Encoder Kit

FULL 8-BIT ^k\

LATCHED OUTPUT M V^K \

19-KEY KEYBOARD W * ^M^ \

The JE600 Encoder Keyboard Kit provides two separatehexadecimal digits produced from sequential key entriesto allow direct programming for 8-bit microprocessoror 8-bit memory circuits. Three additional keys are pro-vided for user operations with one having a bistableoutput available. The outputs are latched and monitoredwith 9 LED readouts. Also included isa key entry strobe.Features: Full B-bit latched output for microprocessoruse. Three user-define keys with one being bistableoperation. Debounce circuit provided for all 19 keys.9 LED readouts to verify entries. Easy interfacing withstandard 16-pin IC connector. Only +5VDC requiredfor operation. Size: 3«"H x 8V."W x 8K"0

JE600/DTE-HK ^j&'^TSSS) ....$99.95

icenn i/.* 19-Key Hexadec. Keyboard. tf-CQ QC

JbOUU IXII PC Board LCmpnts. (no case}. ,QKKf.9D

K19 19-Key Keyboard (Keyboard only) .... $14.95

DTE-HK (case only—3ViMHx8W."Wx8V«"D) $44.95V

Circle 180 on inquiry card.

BYTE September 1981 487

*v

£*>v

"THE BIG BOARD"OEM - INDUSTRIAL - BUSINESS - SCIENTIFIC

SINGLE BOARD COMPUTER KIT!

Z-80 CPU! 64K RAM!

*%,

THE FERGUSON PROJECT: Three years in the works, and maybe too good to be true. A tribute to hard headed,no compromise, high performance, American engineering! The Big Board gives you all the most neededcomputing features on one board at a very reasonable cost. The Big Board was designed from scratch to run thelatest version of CP/M*. Just imagine all the off-the-shelf software that can be run on the Big Board without anymodifications needed! Take a Big Board, add a couple of 8 inch disc drives, power supply, an enclosure, CRT.,and you have a total Business System for about 1/3 the cost you might expect to pay.

FEATURES: (Remember, all this on one board!)

$649

00 <64K K|T

BASIC I/O)

FULLY SOCKETED!

SIZE:8'Ax 13% IN.SAME AS AN 6 IN. DRIVE.REQUIRES: »5V @ 3 AMPS+ - 12V @ .5 AMPS.

64K RAM

24 x 80 CHARACTER VIDEO

Uses Industry standard 4116 RAM'S. All 64K Is available to the user, our VIDEOand EPROM sections do not make holes in system RAM. Also, very special carewas taken in the RAM array PC layout to eliminate potential noise and glitches.

Z-80 CPU

With a crisp, flicker-free display that looks extremely sharp even on smallmonitors. Hardware scroll and full cursor control. Composite video or split videoand sync. Character set Is supplied on a 2716 style ROM, making customizedfonts easy. Sync pulses can be any desired length or polarity. Video may beinverted or true. 5x7 Matrix - Upper & Lower Case

Running at 2.5 MHZ. Handles all 4116 RAM refresh and supports Mode 2INTERUPTS. Fully buffered and runs 8080 software.

FLOPPY DISC CONTROLLER

SERIAL I/O (OPTIONAL)

Full 2 channels using the Z80 SIO and the SMC 8116 Baud Rate Generator. FULLRS232! For synchronous or asynchronous communication. In synchronousmode, the clocks can be transmitted or received by a modem. Both channels canbe set up for either data-communication or data-terminals. Supports mode 2 Int.Price for all parts and connectors: $85.

Uses WD1771 controller chip with a TTL Data Separator for enhancedreliability. IBM 3740 compatible. Supports up to (our 8 inch disc drives. Directlycompatible with standard Shugart drives such as the SA800 or SA801. Drives canbe configured for remote AC off-on. Runs CP/M* 2.2.

TWO PORT PARALLEL I/O (OPTIONAL),

Uses Z-80 PIO. Full 16 bits, fully buffered, bi-directional. User selectable handshake polarity. Set of all parts and connectors for parallel I/O: $29.95

BASIC I/O

Consists of a separate parallel port (Z80 PIO) for use with an ASCII encodedkeyboard lor input. Output would be on the 80 x 24 Video Display.

REAL TIME CLOCK (OPTIONAL)

Uses Z-80 CTC. Can be configured as a Counter on Real Time Clock. Set of sparts: $14.95

64K RAM KIT

SYSTEM C

DMPARISONTalk about bangs per buck! The prices shown forS100 kits were taken from the July 1980 BYTE.This will give some basis for comparison betweenthe Big Board and a similar system implementa-tion on the S100 Buss.

B0 X 24 Video Kit

365.00

235.00

Z-80 CPU Kit

.. 185.95

SER & PAR. I/O

129.95

45.00

SUB TOTAL

$1330.90

CP/M* 2.2 FOR BIG BOARD

The popular CP/M" D.O.S. modified by MICRONIXSYSTEMS to run on Big Board is available for $150.00.

PC BOARD

Blank PC Board wilh Rom Set and Full Documentation.$199.00

PFM 3.0 2K SYSTEM MONITOR

The real power of the Big Board lies in its PFM 3.0 on board monitor. PFM commands include: Dump Memory, Boot CP/M*, Copy, Examine, Fill Memory, Test Memory, Go To.Read and Write I/O Ports, Disc Read (Drive, Track, Sector), and Search. PFM occupies one of the four 2716 EPROM locations provided.Z-80 is a Trademark of Zilog.

Digital Research Computers

** (OF TEXAS) '

P.O. BOX 401565 • GARLAND, TEXAS 75040 • (214) 271-3538

TERMS: Shipments will be made approximately 3 to 6 weeks after wereceive your order. VISA, MC, cash accepted. We will accept COD's (for theBig Board only) with a $75 deposit. Balance UPS COD. Add $3.00shipping.

USA AND CANADA ONLY

•TRADEMARK OF DIGITAL RESEARCH.

NOT ASSOCIATED WITH DIGITAL RESEARCH OF CALIFORNIA, THE ORIGINATORS OF CPM SOFTWARE"1 TO 4 PIECE DOMESTIC USA PRICE. cjrc|e 11(J on inquiry card.

DIGITAL RESEARCH COMPUTERS

(214)271-3538

32K S-100EPROM CARDNEW!

$79,95

KIT

USES 2716s

Blank PC Board - $34

ASSEMBLED & TESTEDADD $30

SPECIAL: 2716 EPROM's (450 NS) Are $9.95 Ea. With Above Kit.

7. Any or all EPROM locations can bedisabled.

8. Double sided PC board, solder-masked,silk-screened

9. Gold plated contact fingers.

10. Unselected EPROM's automaticallypowered down for low power.

11. Fully buffered and bypassed.

KIT FEATURES;

1 Uses +5V only 2716 (2Kx8) EPROM's

2 Allows up to 32K of software on line1

3 IEEE S-100 Compatible.

4. Addressable as two independent 16Kblocks.

5. Cromemco extended or Northstar bankselect.

6 On board wait state circuitry if needed. 12. Easy and quick to assemble.

32K SS-50 RAM

$29900 k,t

For 2MHZAdd $10

„.'.. .JBiiHlti ■■■HBIIBfc.v. -IBBBBBC) RMHUttHBMjLL'iftMilHB »■«■■■■■E-' HI1HHBH BMUHtiHHi

Blank PC Board$50

For SWTPC6800 - 6809 Buss

Support IC's

and Caps

$19.95

Complete Socket Set

$21.00

Fully Assembled,

Tested, Burned In

Add $30

At Last! An affordable 32K Static RAM with full6809 Capability.

FEATURES:

1. Uses proven low power 2114 Static RAMS.

2. Supports SS50C - EXTENDED ADDRESSING.

3. All parts and sockets Included.

4. Dip Switch address select as a 32K block.

5. Extended addressing can be disabled.

6. Works with all existing 6800 SS50 systems.

7. Fully bypassed. PC Board is double sided,plated thru, with silk screen.

16K STATIC RAM KIT-S 100 BUSS

PRICE CUT!

$1699?,T

JIIIIIIIIIEIIIIIIIllllllIIIIIIIIII

16K STATIC RAM SS-50 BUSS

PRICE CUT!

I II

*159

KIT

liilllllilllllll

iiiiiiiiiiiiiiii

FULLY STATIC!

BLANK PC BOARD W/DATA-$33

LOW PROFILE SOCKET SET-$12

SUPPORT IC'S & CAPS-$19.95

KIT FEATURES: -

1. Addressable as four separate 4K Blocks.

2 ON BOARD BANK SELECT circuitry. (Cro-memco Standard1). Allows up to 512K on line!

3 Uses 2114 (450NS) 4K Static Rams

4. ON BOARD SELECTABLE WAIT STATES

5. Double sided PC Board, with solder mask andsilk screened layout. Gold plated contact fingers

6. All address and data lines fully buffered ASSEMBLED & TESTED-ADD $35

7. Kil includes ALL parts and sockets

8. PHANTOM is jumpered to PIN 67.9 LOW POWER: under 1.5 amps TYPICAL fromthe *8 Volt Buss

10. Blank PC Board can be populated as anymultiple of 4K.

FOR 2MHZADD $10

■ - ■ . . ..

FOR SWTPC6800 BUSS!

OUR #1 SELLINGRAM BOARD!

ASSEMBLED ANDTESTED - $35

KIT FEATURES

1 Addressable on 16K Boundaries

2 Uses 2114 Static Ram3. Fully Bypassed

4 Double sided PC Board Solder maskand silk screened layout

5 /^'l Parts and Sockets included

6 Low Powei' Under 1 5 Amps Typical

BLANK PC BOARD—$35 COMPLETE SOCKET SET—$12

SUPPORT IC'S AND CAPS—$19.95

«#» STEREO! %n„

S-100 SOUND COMPUTER BOARD

COMPLETE KIT!$3495

(WITH DATA MANUAL)

At last, an S-100 Board that unleashes the full power of twounbelievable General lnstrumentsAY3-8910NMOS computersound IC's. Allows you under total computer control togenerate an infinite number of special sound effects forgames or any other program. Sounds can be called in BASIC,ASSEMBLY LANGUAGE, etc.KIT FEATURES:

* TWO Gl SOUND COMPUTER IC'S.

* FOUR PARALLEL I/O PORTS ON BOARD.

* USES ON BOARD AUDIO AMPS OR YOUR STEREO.

* ON BOARD PROTO TYPING AREA.

* ALL SOCKETS. PARTS AND HARDWARE ARE INCLUDED.» PC BOARD IS SOLDERMASKED, SILK SCREENED, WITH GOLD CONTACTS.

* EASY. OUICK. AND FUN TO BUILD. WITH FULL INSTRUCTIONS.

* USES PROGRAMMED I/O FOR MAXIMUM SYSTEM FLEXIBILITY.Both Basic and Assembly Language Programming examples are included

SOFTWARE:

SCL™ is now available! Our Sound Command Language makes writing Sound Effects programsa SNAP! SCL™ also includes routines for Register-Examine-Modify, Memory-Examine-Modify,and Play-Memory. SCL™ is available on CP/M' compatible diskette or 2708 or 2716, Diskette -$24.95 2708 - $19.95 2716 - $29.95. Diskette includes the source. EPROM'S are ORG atE000H (Diskette Is 8 Inch Soft Sectored)

BLANK PC

BOARD W/DATA

$31

SPECIAL PURCHASE!

UART SALE!

TR1602B - SAME AS TMS6011,AY5-1013, ETC. 40 PIN DIP

TR1602B

$2

95

EACH

4 For $10

00

CRT CONTROLLER CHIPSMC #CRT 5037. PROGRAMMABLE FOR 80 x 24, ETC. VERY RARESURPLUS FIND. WITH PIN OUT. $12.95 EACH.

4K STATIC RAM

National Semi. MM5257. Arranged 4K x 1. +5V, 18 PIN DIP. ALower Power, Plug in Replacement for TMS 4044. 450 NS.Several Boards on the Market Will Accept These Rams. SUPERSURPLUS PURCHASE! PRIME NEW UNITS!8 FOR $16 32 for $59.95

I Digital Research Computers9 (OF TEXAS) '

P.O. BOX 401565 • GARLAND, TEXAS 75040 • (214) 271-3538

NEW! G.I. COMPUTER SOUND CHIP

AY3-8910. As featured in July. 1979 BYTE1 A fantastically powerful Sound & MusicGenerator. Perfect for use with any 8 Bit Microprocessor. Contains 3 Tone Channels.Noise Generator. 3 Channels of Amplitude Control. 16 bit Envelope Period Control, 2-8Bit Parallel I/O. 3 D to A Converters, plus much more' All in one 40 Pin DIP. Super easyinterface to the S-100 or other busses. $11.95 PRICE CUT!

SPECIAL OFFER: $44^5 each Add $3 for 60 page Data Manual.

TERMS: Add $2.00 postage. We pay balance. Orders under $15 add 75<thandling. No C.O.D. We accept Visa and MasterCharge. Tex. Res. add5%Tax. Foreign orders (except Canada) add 20% P & H. Orders over $50, add85$ for insurance.

•TRADEMARK OF DIGITAL RESEARCH.

WE ARE NOT ASSOCIATED WITH DIGITAL RESEARCH OF CALIFORNIA, THE SUPPLIERS OF CPM SOFTWARE.

Circle 118 on inquiry card.

□

J J J

• .41 ft

^ .:» ia k ^ <a ®

y J VVv .

Veibatim

'•••

o__ <3t 3 $T d si

..

5SS toll free (BOO) 423-5922

MCP1053M4 Duol77tkD/Stded..

..UST PRICE $1888.00

1.2MB S-lOO Subys. OIIB PRICE $1395.00

MCP1053M2 Dual 77 tk s/sided..

..LIST PRICE $1534,00

«OKb S-lOO Subsys. OUR PRICE S 995.00

VISTA PRINTER

VISV30025 25 CPS Dcrisy Wheel LIST PRICE $189500

OUR PRICE $1695.00

VBV30045 45 CPS Daisy Wiieel LIST PRICE $895.00

OUR PRICE $1995.00

MCP1043M2 SNGL 77 tk S/sided..

..LISTPRICE? 939,00

315KB S-lOO Subsys. OUR PRICE $ 695.00

MCP1037M2 DualTRS-80 LIST PRICE $1301.00

77 tk Addon OUR PRICE $ S50.00MCP1027M2 SNGL.THS-80.,:.':....:..;...........USTPRICES 689.00

77tk Addon OUR PRICE $439.00

NEW DOS 80Extended TRS-80 DOS

PMCE

APP395 ,'• Supplied on 35 track $149.00

APP 39577 Supplied on 77 track SB9.ob

IF SIMULTANEOUSLY PURCHASED WITH A,. : iaCROPOUS DISK DRIVE .'... '"' ■.APP395M Supplied on 35 track . SIOO.OO

APP395M77 '^ppuedon77*rcrci SBO.OO

3M SCOTCH DISKETTES

livstar b-30Q.Baud Acoustic

NOVCAT 0300BaudAcoustic ..........

HWraX»T;a3^-3BaudDliect.......,.'...

NOVAUTOCAT 0-300 Baud Direct....

(kAUto Answer -KOVAPLCAfO-30oi3treci.,....:.....

APPLE MODEM AUTO ANS.NOVMIKE SOTERMKE,...

...UST PRICE $199.00

SALE PRICE $129.00....UST PRICE $198.00

OUR PRICE $175.00...LIST PRICE $199.60

OUR PRICE $195.00...UST PRICE $295.00

OUR PRICE S250.O0UST PRICE $359.0©

OUR PRICE S359.00 PRICE $15.95

SUM/

. Price

fart Ho.

Dana,

Sectoring

Box/lO

MMM-740-0

,. . 1/Sgl '

8" -

Soft-IBM. ■•'.".*:■-.

$399;

MMM-740/20

2/sgl

' Soft-IBM -, — .

$75.00

MMM-740/32 ..

.. JXsgl

■32-$luigartBOf--'

$39.95

MMM-740/232

'r^/M, '

32-Shugart SOL .'.''

$79.00

MMM-741-O .:.

;i/dbi

Soft-SKugqrt Dbl

$59.00

mm-7430

*%%.

(2nd) SofMBM

sae.oo

MMM-744-0

tfsgl.

Soft-Shugart

SA4QQ:t$S&$Qt)

$39.95.

MMM-744-10

.■ 1/sgl

Soft/10'SA4CO

- $39.95

MMM-744-16 ,

Vscfl

j? Sdtt/16 Mlcropoils

$39.95

CIARCIA'SCIRCUIT CELLAR

Micrdrriouth lor use on Apple Dor other parallel ports AScTFeatured to June BYTE "--.-

MMMI.94VOAW.-"->-.^»—••• ■■....■....■•■..•■ ....... S149.0p

Micromouth iof use ol.TJjS-^ Model 1eairrpifite with cable,-AC Adapter, less^enoipsure A81T.

MM-94VOTRS! UL.i. ........,....:„;:..„:...........„. $169.00'

Expansion Interface tor TRS-80 Model 1 with DATASEPARATOR,"32K-. b(:RAM, and Cenfrortcs Ertater port. AStT.Fegturediri MARCH BYTE.M&H-DISK80 $429.60

I/O Interface fpr TRS-80, Features" 50-19200 baud KS-232GSerial port and Centronics printer port. Connect up to 16'.COtiJMWs to either Keyboard 6r''Exr^.nslbn"Jnt€irfaC.e.Fearuiea'in.Juhe BO BYTEMlllk;dl«-*b~.y..:.™,.^,........., .....,„.....;. SW9O0

<jif^6t(29£ on. InquiryJcaid:

FLUKE DMM'S

HANDHELD

FLUD800A 3.5Dig6Fund

FLVD802A 3.5Pig 7 Fund, '.

FLUD804A 3.5 Dig 9 Fund. PRICE

BENCH OS HELD

FLUD810 '. 3.5ptg.'ACOper^ ..PRICE

FLUD8U 35 Dig. AC/DC Opft. '...:*...... ......PRICE:

GET A CARRYINS CASE FOR 1*WITH ANY FLUKE DMM

HICKOK DMM'SHANDHELD

MCLX303 3.5Dlcr,fiDC PMC1

HICLX304 3.5 Dig. Low Power Ohms .....,:. PRIC!

BENCH ORFTELD

MCMX333 3.5 Dig, ^rttli Varipitch

. andLogltrak.. ."....i'pflCB

NLS MINISCOPES

NLSMS230 D/Trace 30 MHZ ,

LCD Touch Test.

uch Test Bat..

HLSTROi ,: Touch Test 20.V

HLSTT20B TT20 w/Batteries..

HLSMS15 :'S/Tracel5MHZ .....,,USTPRICE$3

OUR PRICE $3-

NLSMS215 D/Tracel5MHZ UST PRICE $4

-.-"';;/).'■'• 0URPRICE8*

NLSMS230 . D/Trace 30 MHZ :. .LISTPRICE$<

:-":.:''.'. . OURPRICES5

NLSTTS1 LCD Touch Test. UST PKIC£$<

SALEPRICES4

uch test Sat UST PRICES!

SALE PRICE $4

MLSTHO i., ,;■ .|ouch Test2Q.S:..:. v,,..)...-.::.... LIST. PRICE S'

OUR PRICE $3

HLSTT20B■,;, TT20w/Batt«iries...:.,.. .LISTPRICES"

- SALEPR1CES4NLS4H4I : Delvw« Joi Robe'-...;.;..!,..-,--■■/:.,■. ffOGt iHLS41-140 ' Case tor MS15.MS215 8! TT20:....... PRICES

-"o,:.^...:...:..,-..:;...^;»rices.

*r

\

■-*k; _ JSKK2

rirrrmiii

12 Inch GREEN.

013 13 Inch COLOR.

SANYO VIDEO MONITORS

K» 9tochBJcW LIST PRICE $235.00

OUR PRICE S198.00OU BlnchB&W UST PRICE $340.00

OUR PRICE $3I0.OO112 121nchGREEN LIST PRICE $360.00

OUR PRICE $325.00OU 131nch COLOR LIST PRICE $550.00

OUR PRICE $495.00

HITACHI OSCILLOSCOPES

I 15MHZ&T. LIST PRICE $735.00

OUR PRICE $629.00

B 30MIZ D.T. w/Delay LIST PRICE $995.00

OUR PRICE $819.00t 20 MHZ D.T. LET PRICE $860.00

SALE PRICE $775.00! 35MHZD.T.w/Delay LIST PRICE $1150.00

SALE PRICE $950.00)B 5QMHZ D.T.w/VarlDelay..LIST PRICE $1745.00

OUR PRICK CALL3 100MHZD.T.wyVcrilDelayLIST. PRICE $239000

OUR PRICK CALL

CCS PRODUCTS APPLE

A. Calendar/Clock S109.95

IA Programmable Time: $103.00

iA Analog to Digital Converter.......,....:... $99.95

A Asynchronous Serial Interface . $139.00

IA Parallel Interface ...... $107,95

IA Centronics Parallel Interlace $107.95

>A !' Extender Board . S30.00

LE PRODUCTS

MORROW HARD DISK

MDSM26S26MBS-lOOSubsystem LISTPRICE $4495.00

SALE PRICE $3495.00

B & K OSCILLOSCOPE ccs 22°OA

BKPI405 5MHZ S. T. LISTPRICE $315.00

SALE PRICE $280.00

BKP1420 15 MHZ D.T. Portable.. UST PRICE $825.00 ,.

SALE PRICE S750.OOBKP1530 30 MHZ D.T. _-.—,«

VarL Delayed LIST PRICE $136500 TEMC5U3

SALE PRICE CALLBXPUOO lOOMHZQT. T

Vart. Delay LIST PRICE $2575.00

SALEPPJCE CAM. jg^^

B & K TEST EQUIPMENT ^^

BKP3010 Function Generator LIST PRICE $220.00 ___,_„,

OUR PRICE S198.00 ™n™°BKP3020 Sweep/Funct.Generator LIST PRICE $379.00

OUR PRICE $349.00 teirfdoKP3300 5 MHZ Pulse Generator....LIST PRICE $350.00

SALE PRICE $320.00

VISTA APPLE PRODUCTS smJSOIK

VIS150 Type Ahead Butter LIST PRICE $49.95

SALE PRICE $44.95

VTSA800 8" Floppy Controller LIST PRICE $595.00

CA, AX, HIORDER

(213) 709-5464

CCS MAINFRAMES

S-10012slot UST PRICE $43400

OUR PRICE $410.00

TEI MAINFRAMES

12 slot desk UST PRICE $68500

OUR PRICE $615.0022 slot desk UST PRICE $845.00

OUR PRICE $760.0012 slot rack mount LIST PRICE $80000

OUR PRICE $720.0022 slot rack mount LIST PRICE $94500

OUR PRICE $850.00801R desk LISTPRICE $53500

OUR PRICE S485.00SOlRdesk UST PRICE $725.00

OUR PRICE $670.00

8" DISK DRIVES

D/Dens s/Slded REG PRICE $495.00

SALE PRICE $425.00 2/S39S.OO —

D/Dens D/Slded Each $625.00

IEEE-488 Interface

IS, 2P Interface 3"....:.Assembled 8c Tested.

...UST PRICE $475.00SALE PRICE S415.00

.... UST PRICE $175.00SALE PRICE $165.00

...LIST PRICE $225100SALE PRICE $185.0©

SALE PRICE S550.00 2 or more $600.00 «a.

PRIORITY ONE ELECTRONICS t» ^

9161-B DEERING AVE. • CHATSWORTH, CA 91311 lU Iw

ORDER TOLL FREE (BOO) 423-5922 CA, AK, HI CALL (213) 709-5464 ~rn*

terms, US., VISA. MC. BAG. (Shock Money1. Order. US Funds Only. CA residents add 6% Sales Tax. MINIMUM PKEPAID ORDER S15.CO.include MINIMUM SHtPPING.St HANDLING ot $2.50 lot the first 3 lbs., plus 25e lor each additional pound. Orders over 50 lbs. sentfreight, collect. Just in case, please Include your phone no. Prices subject to change without notice. We will do our best to main-■ tain prices thru-September 195L SOCKET and CONNECTOR prices based on GOLD, not exceeding $700.00 per or

Sales Prices Valid only if *OU mention publication and month. Credit Card orders will be charged appropriate freight.

Circle 299 on Inquiry card.

'////AT^S,

S-lOO ROM

FBI PHOM PROGRAMMER - SSM

'programs 2708 or 2716's, operatesas a 4KI8K EPROM board as well.

SSMPB1K Kit $154.95

SSM-PB1A A&T $219.00

ECONOROM 2708 ■ QODBOUT

16K x 8 EPROM Board using 2708, Power onjump to any 256 byte

GBT 125UGBT 125AGBT 125C

UnKit.A&T. .CSC. .

$85.00$120.00$175.00

GBT 171AGBT 171CGBT CPM80

GBT CPM86

S-lOO CPU

CPU-Z - QODBOUT

214 MHZ Z80 CPU 24 Bit Addressin,

GBT 160U UnKit $225.00

GBT160A A&T $199.01

GBT160C CSC 3-6 MHZ $375.00

S-lOO DISK CONTROLLERS

DISK 1 ■ QODBOUT

DMA, Soft Sector, Controls 8" or S'A",single or double density

AST $450.00

CSC $556.00

CP/M 2.2 lor Z80/8085 withManuals & BIOS 8" S.D. disk $175.00CP/M tor 8086 with manuals

& BIOS 8" SID disk $300.00

2422A ■ CA. COMP. SYST.I/O Mapped, controls 8" or 5'/.", singleor double densityCCS-2422 A&T with CPM 2.2 8" S.D... .

DISK JOCKEY 1 - MORROW. M Single density disk controller with

\\ serial I/O, controls 8"

I..DSDJ1108 A&T

DISK JOCKEY 2D - MORROWI/O Mapped, controls 8", single ordouble density, serial t/0DSDJ2208 A&T

r

$365.00

$219.00

$375.00

DUAL PROCESSOR 8085-8088 ■ QODBOUT

5 MHZ Provides true 16 Bit Power with a standard

8 bit S-100GBT 1612UGBT 1612AGBT 1612C

GBT161UGBT161AGBT161C

bus

UnKit $295.00

A&T $399.00

CSC $498.00

BOARD WITH 8085 ONLY

UnKit $235.00

A&T $305.00

CSC $399.00

2610 Z80 CPU-CA. COMP. SYST.

2/4 MHZ Z80A CPU with RS-232C Serial I/O Port

complete with Monitor PROM for 2422 Disk Controller

CCS 2810 A&T..- $280.00

CBS ZSO CPU - S.S.M.

2/4 MHZ will accept 2716, or 2732, or RAMRUN/STOP and single step switches

SSMCB2K Kit $260.00

SSMCB2A A&T $310.00

SSMZ80M SSM Z80 Monitor $89.00

CBIA SOSO CPU - S.S.M.

8080CPU, 1K RAM, Holds 1 2708,

1 8 Bit parallel input port.

SSMCB1A Kit $183.00

SSMCB1A A&T $225.00

SSM8080M SM 8080 Monitor $59.00

S-IOORAM

64K STATIC RAM - QODBOUT

RAM 17, 10 MHZ, 2 Watt, DMA Compatable

GBT-175A48 A&T48K $950.00

GBT-175C48 CSC 48K $1050.00

GBT-175A64 A&T 64K $900.00

GBT-175C64 CSC 64K $1395.00

64K DYNAMIC RAM ■ CCS

4 MHZ, on board refresh, DMA compatable,

24 bit address.

CCS-2065A A&T $599.00

32K STATIC RAM • QODBOUT

RAM 20 10 MHZ, 4K byte block disable,

available 16, 24, or 32K

GBT-164A16 A&T 16K $319.00

GBT-164C16 CSC 16K $418.00

GBT-164A24 A&T 24K $449.00

GBT-164C24 CSC 24K $539.00

GBT-164A32 A&T 32K $499.00

GBT-164C32 CSC 32K $720.00

32K STATIC RAM - CCS

4 MHZ, Bank select, 8/16 bit dataCCS-2032 A&T 32K $599.00

16K STATIC RAM - GODBOUT

RAM 14, 10 MHZ, 24 bit addressing

GBT-143A A&T 16K $169.00

GBT-143C CSC 16K $399.00

16K STATIC RAM - CCS4 MHZ, 8/16 bit data, bank select

CCS-2116A A&T 16K $299.00

BK STATIC RAM - QODBOUT

Econoram II 2MHZ, 8K, No doubt, the most

popular S-100 RAM ever built.

GBT-114U UnKit 8K $99.95

DISK DRIVES

SOIR - SHUQART

Single sided double density most popular 8" drive

SHU80IR $425.00 ea. or 2 or more $395.00

SHUSA80IRM Manual for 80IR drives $10.00

DT-8-QJUME

Data track 8 double sided, double density

QMEDT8 $625.00 ea. or 2 or more $600.00

DISK CABINETS

V-lOO ■ VISTA

Dual 8" drive cabinet with power supply.Rack or Desk Mount

VIS-V100 $395.00

SINGLE 8" Q.T.

Single 8'* cabinet with power supply

QTCDDC8 $195.00

VIS-9801

VIS-9802

5" CABINETS • VISTA

Single 5" with P.S

Dual 5" with P.S

$75.00$95.00

S-lOO DISK SUBSYSTEMS

DISCUS SINGLE SIDES MORROW

8" DBL Density drives with cabinet, power supplycontroller, with CP/M 2.2 and Microsoft Basic

MDSF1218 Single Drive System $950.00

MDSF1228 Dual Drive System $1598.00

DISCUS DOUBLE SIDED - MORROW

8" DBL Density/sided drives with cabinet Power

supply controller, with CP/M 2.2 and Microsoft .Basic

MDSF2218 Single Drive System $1250.00

MDSF2228 Dual Drive System $2195.00

26MB HARD DISK - MORROW

Special purchase, limited stock - 26MB formatted harddisk complete with cabinet, P.S., Controller, CPM 2.2

and Microsoft BasicMDS-M26S 26 MB Subsystem List $4495.00

SALE• $3495.00 •

SAVE $1,000.00MICROPOLIS

Priority 1 Electronics is the

worlds largest distributors of

MICROPOLIS disk sub Systems

CALL FOR PRICES

htfgSfr*

PRIORITY

S-lOO I/O BOARDS

SYSTEM SUPPORT 1 - QODBOUT

Serial port /software prog baud), 4K EPROM or

RAM provision, 15 levels of interrupt, real time clock,

optional math processor

GBT-162U UnKit $295.00

GBT-162A A&T $360.00

GBT-162C CSC $460.00

GBT-9512 Math Chip $195.00

MPX CHANNEL BOARD - QODBOUTI/O Multiplexer, using 8085A-2 cpu on board

GBT-166AGBT-166C

GBT-133 AGBT-133C

$450.00$550.00

A&T.

CSC

INTERFACES I - QODBOUT

Two Serial I/O

A&T $219.00

CSC $298.00

INTERFACES U - QODBOUT

Three parallel, one serial I/O board

GBT-150A A&T $219.00

GBT-150C CSC $298.00

MULTI I/O - MORROW DESIGNSThree Serial, Two parallel

MDSMB3200 A&T $309.00

SWITCHBOARD-MORROW DESIGNSTwo serial I/O, four parallel I/O,one status port, one strobe port

MDSSB2411 A&T $239.00

1/02 - SSM

One parallel input, one parallel output, proto work

area

Kit $69.00

A&T $89.00

I/04 - SSMTwo serial I/O, two parallel I/O

Kit $210.00

A&T $260.00

SBI-SSM

Music synthesizer board

Kit $249.00

AST $310.00

Software $ 25.00

S-lOO VIDEO BOARDS

SPECTRUM ■ QODBOUT

Color Graphics board with Parallel I/O.

GBT-144U UnKit $299.00

GBT-144A A&T $349.00

GBT-2D Sublogtc Software $ 35.00

VB ■ 3 S.S.M.

80 x 24 or 48 character video display Memory Mapped,Parallel Keyboard port

SSMVB3K24 Kit 80x24 $349.00

SSMVB3A24 A&T 80x24 $429.00

SSMVB3UP Upgrade Kit $30.00

VB2-SSM

I/O Mapped Video Board, with Parallel Keyboard port.64x16

SSMVB2K Kit $169.00

SSMVB2A A&T $229.00

VBIC - SSM

Memory Mapped Video Board 64x16 character displayor 64x16 graphics dlslplay

SSMVBICK Kit $169.00

SSMVBICA A&T $220.00

S-lOO MOTHERBOARDS

MOTHERBOARD • QODBOUT

Active termination, 6-12-20 slot

SSMI02KSSMI02A

SSMI04KSSMI04A

SSMSBIKSSMSBIASSMSBIS

GBT-153UGBT-153AGBT-154UGBT-154AGBT-155UGBT-155A

Unkit 6 slot $ 89.00

A&T 6 slot $119.00

Unkit 12 slot.A&T 12 slot. .Unkit 20 slot.A&T 20 slot..

$129.00$149.00$174.00$189.00

SSMOB1KSSMOB1A

ELECTRONICS

WUNDERBUSS - MORROW DESIGNS

Active termination, 8-12-20 slot,

peripheral power outputs

(5V@1A, 12V @ 500ma, - 12V <s> SOOrnal

MDS0800A A&T 8 slot $129.00

MDS1200A A&T 12 slot $149.00

MDS2000A A&T20 slot $199.00

S-lOO MISC.

CK017 ACTIVE TERMINATOR-GODBOUT

GBT-106U Kit $ 34 :<

2520 - CCSExtender/terminator, Active and/or passive

CCS2520AK Kit $

EXTENDER/LOGIC PROBE-MULLEN

MUL-CK004 Kit $ 59.00

OBI VECTOR JUMP - SSMwith prototyping area

Kit $

A&T $

65.0090 00

9161-B DEERING AVE. • CHATSWORTH, CA 91311

*fc*8W

Terms. U.S., VISA. MC. BAC, Check Money Order, U.S. Funds Only. CA residents add 6% Sales Tax. MINIMUM PREPAID ORDER $15.00. Include MINIMUM SHIPPING & HANDLING olS2.50 lor the first 3 lbs., plus 25C lor each additional pound. Orders over 50 lbs. sent freight, collect. Just In case...please include your phone no. Prices subject to change withoutnotice. We will do our best to maintain prices thru September 1981. SOCKET and CONNECTOR prices based on GOLD, not exceeding S700.00 per oz.

Sales Prices Valid only if YOU mention publication and month. Credit Card orders will be charged appropriate freight.

wftmm

_

" Ctrcf,

e 300 on inquiry card.

STAR MODEM

FROM

LIVERMORE

LIST PRICE

0 lo 300 baud data rate. Compatible IW""«UU

with Bell 103 and 113. Answer/ SALE PRICE

Originate. Full/Half Duplex. Special £l^}f\ f\^\

sell test features. »J> L&7.\J\*/

RS232 and "D" SUB-MINIATURECONNECTORS

5B

i|l|l|i|iiMii|i|i

"T

MALE T

uuuuuiiffrrntTn'

1 1 [EliAIC r '

P= Plug, Male Type • S- Socket. FemaleType-C= Cover, Hood

PART NO.

CND-DE9P

CND-DE9S

CND-DE9C

CND-DA15P

CND-DA15S

CND.DA15C

CND-DB25P

CND-DB2SS

CND-DB51212

CND-P25H

CND-DB51226

CND-DC37PCND-DC37SCND-DC37CCND-DD50PCND-DD50SCND-DD50CCND-D2D41B

CND-RS2328F

CND-5730360

DESCRIPTION

9 pin male9 pin lemale

9 pin cover

15 pin male15 pin female

15 pin cover

25 pin male25 pin lemale

1 pc. grey hood

2 pc. grey hood2 pc. block hood

37 pin male

37 pin lemale

37 pin cover

50 pin male

50 pin female

50 pin cover

Hardware set 2 pr.

RS232, DB25P, EIA

Glass 1 cable 8 con. 8 II

Cent. 700 Series

Printer connector

1-9

S 2.1D

S 2.70

$ 1.50

S 2.75

S 3.95

S 1.50

S 3.50

S 4.60

S 1.60

S 1.50

$ 1.90

S 5.80

S 8.70

S 1.80

S 8.75SI 1.65

S 2.00

S 1.00

PRICE10-24

S 1.90

S 2.40

S 1.25

S 2.45

S 3.80

$ 1.30

S 3.25

S 4.35

$ 1.45

S 1.25

S 1.65

J 5.10

S 7.70

S 1.55

S 7.75S10.25

S 1.80

S .80

25-99

$ 1.70

S 2.10

$ 1.10

$ 2.15

S 3.20

S 1.10

S 3.00

S 4.20

S 1.30

S 1.10

$ 1.45

S 4.45

S 6.70

S 1.30

S 6.70

S 8.90

S 1.60

S .70

S19.95 S17.95 S15.95$ 9.00 S 7.50 S 6.00

MICROCOMPUTER PRODUCTS

PART NO.

2016P3

2114N3L

5257N3L

2732

2716

2708

PRICE

8/SI00.008/S28.008/$50.00

8/S120.008/S50.008/S32.00

8080 SERIES

PART NO. PRICE

6502 SERIES

PART NO. PRICE

INS BtldilA

INS 8085A

DP8212N

DP8214N

DP8216N

DP8224N

DP8224-4N

DP8226N

DP8228N

DP8238N

INS8250N

INS8251N

INS8253N

INS8255N

INS8257N

INS8259N

INS827SN

INS8279N

S5.50

S19.95

S2.95

$5.25

S2.95

$3.25

S3.95

S3.50

$5.55

$5.55

$15.00

$7.50

$17.95

$6.80

$16.45

$18.00

$59.95

$49.95

6S02

6502A

6520

6522

6530-002

6530-003

6530-004

6530-005

6532M

6551M

$12.95$18.95$8.95$10.95$21.95$21.95$21.95$21.95$21.95$21.95

6800 SERIES

PART NO. PRICE

Z80 SERIES

Z80A S14.95

280AP10 $14.95

Z80ACTC S13.95

Z80ADMA S45.00

Z8OAS1DO $59.95

Z80ASIU1 S59.95

Z80AS102 $59.95

FLOPPY DISCCONTROLLER

MC6800P

MC6802P

MC6808P

MC6809P

MC6821P

MC6828P

MC6840P

MC6845P

MC6847P

MC6850P

MC6852P

MC6854P

MC6860P

MC6862P

MC6875L

MC66710P

MC66750P

UARTS

PART NO

AY51013ATR1602BTR1863IM6402

$11.95$17.95

$9.95$34.95

$5.95$14.95$14.95$31.00$14.95

$5.41

S5.79$24.95$10.89$12.00

$7.40$12.50$12.50

PRICE

$5.95$5.95$6.95$7.95

FD1771B-01FD1791B-01

$24.95$44.95

CompuPro"

GBT-143AList $349.00

- VBSR

10 MHZ 16K A&TSTATICS-100 RAM

$169.00 EaJ3/$450.00

• Operates up to 10 MHZ (90 ns RAM Chips)

• Assembled & Tested • Meets or exceedsall IEEE 696/S-100 specifications (includingtiming). • Fully static design eliminates thetiming problems associated with dynamicmemories. • Switch selectable choice of 24address lines conforming to the IEEE696/S-100 extended addressingspecifications, or 16 address lines as usedin older S-100 systems. • Ideal for multi-userinstallations. • Board is addressable as one16K x 8 block on any 4K boundary. • Switchselectable PHANTOM disable and writeprotect. • + 5 Volt operation (requires noother supply voltages). • Low poweroperation (900 mA typical, 1200 mAmaximum).' 1 year Factory Warranty.

Plugboards

sfmMiiwniw

S-100 "ANY DIP" has lull power andground planes back to back. Boardsaccommodates .3. .4. .6. .9" D:

1-4 5-9 10-24

$24.67 $22.34 $20.02

APPLE PLUGBOARDVector 4609 Peripheral InterlacePlugboard for construction of customcircuits. Plug compatible with AppleII. Commodore PET and Super Kimmicrocomputers. VCT-4609

1-4 5-9 10-24

$20.74 $18.79 $16.84

Universal Microcomputer/

processor plugboard use withS-100 bus. Complete with healsink & hardware. 53" x 10" x1/16".

1-4 5-9 10-24

S22.48 S20.37 $18.26

VCT-8801-1Same as 8800V except plain, lesspower buses & heat sink.

1-4 5-9 10-24

S15.67 S14.24 S12.82

<4.5"

(4.5"

VCT-3682 9.6"

■ S13.63

VCT-3862-2 6.5'

511.04

Hi-Density Dual-In-Line Plug-board lor Wire Wrap with Power& Grd. Bus Epoxy Glass 1/16"44 pin con.spaced 156

VCT3677 9.6"x4.5"

VCT-3667 96" x 4.5"

S13.33

VCT-3677-2B.5"x4.5"

S10.68

Gen. Purpose D.I.P. Boards withBus Pattern for Solder or WireWrap Epoxy Glass 1/16" 44 pincon.spaced .156

WiAMflJWJUUUAtMflU

VCT-3662 6.5"x4.5"

$8.69

VCT-3662-2 9.6" x 4.5"

S10.B5

VCT-3690-12 $26.64

CARD EXTENDER

Card Extender has 100 contacts50 per side on .125 centersAttached connector-is CDmpati

P pattern plugboards lor IC's Ex- ble with S-100 Bus Systems,poxy Glass 1/16" 44 pin con VCT-3690 6.5" 22/44 pin

spaced.156 .156 ctrs. Extenders ...515.66

1/16

jfes*

BOARD

.042 diaholes on0.1 spacing for IC's

Phenolic

PART NO.VCT-64P44-XVCT-169P44-X

Epoxy GlassVCT-64P44VCT-84P44VCT-I69P44VCT-I69P48

SIZE

4.5" x 6.5"4.7" x 17"

PRICE1-9 10-19

x6.5"x8.5"x 17"x 17"

S1.56$3.69

$1.83$2.25$4.61$9.00

$1.40$3.32

$1.65$2.03S4.15

SB.10

ZERO INSERTIONFORCE TEST SOCKETS

2

TRS-80/APPLE

MEMORY EXPANSION KITS4116'sRAMS

from Leading Manufacturers

(16Kxl 200)

8 for $20.00

Add $3.00 for programming Jumpersfor TRS-80 Keybaord

7 r:5^

POWERLINEINSOLATOR

GOF-IBARW3SH.WT. 3 lbs.

List Price $59'5Sale Price$29.00

A MUST FOREVERY OFFICEWITH DATAPROCESSINGEQUIPMENT

1-9S 5.50S 7.50S10.25

TTTTTTr

10-24$5.35$7.25$9.85

•I

iff

25-99$4.95$6.95$9.50

I

■*«>>'.

6 OUTLET

MULTI USE

CORD REEL

SEND $lao

for 60 Page

CATALOG

HSfc SH. WT. 5 LBS.

G0F-CR1 22 It. Cord $24.95GOF-CR50 50 It. Cord $39.95

SPECIAL PURCHASE

GOLD

Q^lBFINLOWPROFILE LC.

C-35 BOOKETS

TIG-16LPPkg.ofiooTIG-16LPPkg.oiiooo SI20.0C

OEMS Stock up at this LOW PRICE

1M-10A List $104.95SPECIAL$69.95 with tubePerfectly balanced fluores-cent lighting with precisionmagnifier lens. Toughthermoplastic shade. Easylens removal. New wire clipdesign permits easy instal-lation and removal offlourescent tube. Comes

LEDU

with plastic shield to pro-tect tube from soiling anddamage.

Colors: Gray. Black, andChocolate Brown. Comeswith one 22 watt T-9 Circlineiluorescent tube, 3 diopterlens. 10 lbs.

PRIORITY I ONE I ELECTRONICS

9161-B DEERING AVE. • CHATSWORTH, CA 91311

ORDER TOLL FREE (800) 423-5922 CA, AK, HI CALL (213) 709-5464

Terms, U.S.. VISA, MC, BAG Check Money Order, U.S. Funds Only. CA residents add 6% Sales Tax. MINIMUM PREPAID ORDER SJ5.0O.Include MINIMUM SHIPPING 8c HANDLING ol S2.50 lor the Hist 3 lbs, plus 25C lor each additional pound. Orders over 60 lbs. sentfreight, collect. Just In case.please Include your phone no. Prices subject to change without notice. We will do our best to main-tain prices thru September 1981. SOCKET and CONNECTOR prices based on GOLD, not exceeding S700.00 per oz.

Sales Prices Valid only If YOU mention publication and month. Credit Card orders will be charged appropriate lreighl.

Circle 300 on inquiry card.

Unclassified Ads

FOR SALE: TRS-80 Mode! I Level II with 16 K memory,lowercase installed, in mint condition. Including S200 systemdesk, manual and computer books, and complete library ofgames and software (including Scnpsit package) worth S300.Complete system worth over SI400 for only SI000. MikeClary. 3008 E Meadow Grove Rd, Orange CA 92667. [7I4J998-0155.

FOR SALE: Netronics ELF II microcomputer with 8 K pro-grammable memory. RS-232 interface, cassette-tape interface,Netronics video terminal. Motorola video monitor, Tiny BASICon cassetre. and full documentation. S400 (price negotiable).Mike Heitmann. 114 S Overbrook. St Charles MO 63301, (314]723-3950 weekends or after 4:30 weekdays.

FOR SALE: DEC/Heath H-l 1 16-bit computer. DEC LSI-1 116-bit processor with floating-point processor option, 56 K [28KW, 16-bit) MOS memory, serial port (20 mA or RS-232), dual8-inch disk drive, disk operating system, FORTRAN compiler,and BASIC Spare parts include LSI-1 I processor card, Memorex8-inch disk drive, disk controller, memory, and disk controllerparts. Cables, service manuals, and operation manuals. Newcost over S 10,500. Sell for S6000. Mike, (61 2) 920-2440.

FOR SALE: IBM/Escon Selectnc typewriter (correcting, withlegal keyboard). Eighi months old. Factory-installed RS-232C in-terface with backspace and tab. In new condition, too slow formy purpose. S1600. Also, four Axiom printers, Model EX80IP(parallel). Trouble-free printers in ortginal boxes. My projectcanceled. S425 each or all four for S 1600. J Turner, 309 Mac-Corkle Ave, St Albans WV 25177, (304) 776-3675.

FOR SALE: Decitek paper-tape reader. Easily runs at 600cps. 7-inch rack mount. Complete power supply, parallel inter-face, and documentation. S200 or best offer. Tom Lock, 375Front St, Box B-12. Berea OH 4401 7, (216) 234-2798.

FOR SALE: Godbout Interfacerl 2S; S200, CSI Qume Sprint3 interfacer with 16 K buffer; S450, Jade Big Z Z80 processorcard; SI50, Pnntrol Qume Sprint 3 interface card; S75, Spell-binder word-processing program; S300. All items in excellentcondition with manuals. Kirby Nickell. 2844 Angelique. StJoseph MO 64501.

FOR SALE: BYTE from January 1977 thru August 1977 andMarch 1981. S21. best offer, or trade for the following BYTEs:September 1975 thru October 1976, February 1980. September1980, October 1980. or January 1981. Mark D Ybarra, 2604Bobolink Dr, San Jose CA 95125. (408) 264-7789,

WANTED: Cartridges for Video Brain computer. Also needinstructions for Finance cartridge. Particularly interested inWordwise 2 cartridge and any schematic information. JamesKasperski, 23-01 30 Dr, Long Island City NY I 1 102.

FOR SALE: Zenith/Heath H-l I system. 64 K programmablememory, two 8-inch floppy-disk drives, HT-1 I, and Pascal soft-ware. Fully DEC PDP-1 1/03 compatible. S4200. K W Scholz.8216 Pickering St. Philadelphia PA 19150. (215) 248-0439evenings.

FOR SALE: Heath H-8 computer. Assembled and tested,with manual. Will sell for best offer. David Wong, 1916 GrandCone. New York NY 10457, (212) 294-8087.

FOR SALE: TI-810 printer with full ASCII uppercase andlowercase, floor stand, paper catch, and ribbons. SI 100. HP-232IP interactive video terminal with built-in printer. S2100.Both items purchased for a remote station, but never used andare in brand-new condition. James Leonard. 58 Beverly Dr,Columbiana OH 44408, (216) 482-2291.

FOR SALE: IMSAI PCS 80/30 with 48 K, dual smgle/double-density diskette drives (J megabyte total), InteHigent keyboard[IKB-1J, Leedex VT-100 monitor, and /MDOS. S4000 or bestoffer. Bill Levering, 26 Maple Rd, Westford MA 01886. (617)692-3847.

FOR SALE: Apple II plus 64 K Pascal-language system,Zenith 13-inch color monitor, IDS-440 printer with graphics op-tion, Hayes modem, dual disk drives. Mountain Clock. Con-troller, Cashier, Apple Writer, Apple Post. VisiCalc 1.37. DowJones Stock Evaluator, personal programs, and other ac-cessories. S5900 complete. Fritz E Hockman, 45 GrampianBlvd, Williamsport PA 17701, |7I7J 326-4954 or 368-863 I.

FOR SALE: Rockwell AIM-65 with 4 K programmable mem-ory, ROM-based text editor/assembler, 8 K BASIC m ROM,power supply, and manuals. S475. Greg Vatt, 7170 S LewisWay, Littleton CO 80127. [303) 979-1998.

FOR SALE: Terak 8510/a graphics computer system inperfect working condition. Includes DEC LSI-1 1 processor, 56 Kprogrammable memory, 8-inch floppy drive. 240 by 320 black-and-white graphics on 12-mch video display, full ASCII key-board, and UCSD Pascal software, including volumes 3 thru 5of the USUS library. Excellent for schools, industry, or fanatichobbyists. (Similar systems originally spawned UCSD Pascal.)Cost S8285 new; make offer. Jerome Wood, 6105 Harris,Raytown MO 64133, (816) 356-8290 after 5 PM weekdays.

WANTED: 16 K or 32 K Exidy Sorcerer/Sorcerer II computer.I am primarily interested in the computer itself, but will considersystems with peripherals (cassette or disk, printer, video moni-tor, etc). Please state asking price in first letter—will pay anyreasonable price, depending on condition and age. ChristopherLett, 145 Meadow Ln. New Rochelle NY 10805.

FOR SALE: Set of 8 K Microsoft BASIC ROMs for NetronicsExplorer-85 computer, All documentation included; S60.Wameco MEM-1A 8 K S-100 bus static memory with 300 nslow-power programmable memories; S75. Pat Taylor, 1200 SMarket St, Bloomsburg PA 17815, (717) 784-6173.

FOR SALE: PET/CBM 2001 with 16 K programmable mem-ory plus Skyles Toolkit read-only memory to debug BASIC pro-grams. About one year old. S650 FOB. Many PET programs in-cluded. Also, Divert-A-Matic phone-call diverter. SASE fordescription. S150. Consider exchange for tape answerer. PYoung, 1496 Cherrywood Dr, San Mateo CA 94403, (415)574-4212 or 349-4325.

FOR SALE: SIM-1 microcomputer with 1 K programmablememory, expandable to 4 K and 51 I/O lines. SI35. MikeUnderwood, Rte 3 Box A-594, Troutville VA 24175, (703|977-4337.

FOR SALE: 32 K Exidy Sorcerer. BASIC and AssemblerROMPACs plus Extended Cassette BASIC. RS-232, parallel, dual-cassette control. All documentation plus internal hardware andsoftware manuals. Over S450 worth of software (graphics,games, word processing, data base, utilities, etc\. All in excellentcondition for SI250 or best offer. With Comprint printer, addS500. With 12-inch monitor, add S75. R L Henne, 5870 WoodFlower, Burke VA 22015. (703) 250-5323.

FOR SALE: IMSAI 8080 microcomputer with 48 K memory.Processor Technology boards included are: 3P + S I/O, CUTScassette, GPM. VDM-I. and ALS-8 chip set (4 chips). Cromem-co boards included are: TV Dazzler. ZPU processor, and 8 KBytesaver. Miscellaneous boards are: TB-1 Extender, IMSAI MIOinterface, and others. Comes with Infoton Vistar GTX video dis-play. Software includes: 15 K Extended BASIC, Music System,games, etc. All manuals included. Over S5200 invested, firstoffer over S3300 takes everything. Steve Dover, 821 Laramie,Wilmette IL 60091. [312) 251-4683 evenings.

FOR SALE: Pro-Log Z80 single-board computer. Model7803. for the standard bus. This board is brand new—neverbeen out of its protective package. S 150 or trade for sailboat.Wayne Miller, 83 Brookwood Ct, Elgin IL 60120.

FOR SALE: Pascal Microengme computer manufactured byWestern Digital Corp. The system is fully boxed and factorytested. This is not just a board; it is virtually unused. You get64 K programmable memory and a processor that is optimizedfor the use of Pascal. Asking S3000. but will take the best offerRobert Powers. 75 W Green St. Pasadena CA 91 105, (213)792-0893.

FOR SALE: Two complete SwTPC computers. Each has24 K, MPS, MPC, MPL. JPC fast cassette, two tape decks,CT-64. 9-inch Sanyo, Fast BASIC with files, much software, andall cables. Ready to use. S800 each or S I 500 for both, includingPR-40 printer. Will trade for two CT-82 terminals. HowardJohnson, [207) 244-7444.

FOR SALE: Litton 1241-1251 with Multiplexer GeneralLedger, Payroll, Amortization, Depreciation Software, supplies,etc. Best offer. Alan Phelps, 1664 McDade Est, Conroe TX77304, (713) 756-8889.

WANTED: The United States Yacht Racing Union isdeveloping a Race Management Manual for use by race commit-tees. A section will be devoted to computer and calculator pro-grams. We are seeking programs related to sailing, race scoring,handicapping, measurement rules, etc. A library of these pro-grams is being maintained. A listing of the programs availablewill be included in the manual. United States Yacht RacingUnion. POB 209. Newport Rl 02840.

FOR SALE: Heath/Zenith disk software for H-l 7 disk sys-tem. I changed toCP/M, and have the latest HDOS 2,0 with Ex-tended BASIC, editor, assembler, debugger, etc. With allmanuals and binder, never run. Also, Microsoft BASIC forHeath H-8 or H-89 under HDOS. Latest version supports assem-bly-language subroutines. Never used. Either or both for halfcurrent catalog price. G Hammond, (603) 366-4012 evenings.

FOR SALE: Tano Outpost II 6800 computer. 48 K, twoRS-232 I/O ports, two 5-mch Shugart disk drives, Tano BASIC,COPS II [utility programs), Hemingway editor, compiler, andlink editor. Also, Flex II ROM, Flex li, editor, compiler, anddebugger. Several disks and all manuals. S2000 or best offer.Arthur Shore, (415) 364-5006.

UNCLASSIFIED POLICY: Readers who are soliciting or giving advice, or who haveequipment to buy, sell or swap should send in a clearly typed notice to that effect. To beconsidered for publication, an advertisement must be clearly noncommercial, typed doublespaced on plain white paper, contain 75 words or less, and include complete name andaddress information.

These notices are free of charge and will be printed one time only on a space availablebasis. Notices can be accepted from individuals or bona fide computer users clubs only. Wecan engage in no correspondence on these and your confirmation of placement is ap-pearance in an issue of BYTE.

Please note that it may take three or four months for an ad to appear in the magazine.

FOR SALE: 16 K Commodore PET computer, including ex-ternal cassette drive. Programmer's Toolkit ROM, Soundware'sSoundbox, and assorted programs. Game programs includeMicrochess 2.0, Super Startrek. Tanks, Othello, Backgammon,Breakout, and Bowling. Math programs include Infinite LongDivision, Synthetic Division of Polynomials, and a polar-graphplotting routine. S900. Mike Soma, 1 18 Georgetown PI,McKeesport PA 15135, [412) 751-8075.

FOR SALE: SD Systems boards: SBC-200 Z80 processor;S280, VDB-8024 video controller; S300. Expandoram II 64 K;S250. All assembled and tested at factory, never used. 6months old. Also, California Computer Systems mainframe.12-slot motherboard, and power supply; S290. Xerox word-processing keyboard; S30. 10% off purchase of entire group.John A Maurer. (3 13) 884-0471.

FOR SALE: Recently purchased HP-4IC system, includingHP-4IC calculator, two memory modules, printer with six rollsof paper, card reader with two packs of cards, rechargeablebattery pack, and all manuals, S600. Paul Demes. POB 279,Marshalltown IA 50158. (515) 754-2177 work, 753-3661home.

FOR SALE: Anderson Jacobson 242A acoustfc coupler.Used, but in good condition. Best offer. Greg McDonald. 1434Fenwick Ln, Silver Spring MD 20910, (301J 587-8536.

494 September 1981 © BYTE Publications Inc

Reader Service

Inquiry No.

Page No.

1 47th STREET PHOTO 123

2 A B DIGITAL DESIGN 103

4 AB COMPUTERS 451

5 ABM PRODUCTS 190

6 ACKERMAN DIGITAL SYS 389

• ACTION COMPUTER 85

7 ADAPTIVE DATA & ENERGY 183B ADV.COMP.PROD. 482, 483

9 ADV.MICRO SYS. 126

10 ADVANCED TECH 460398 ADVENTURE INT'L 125

11 AFTERTHOUGHT ENG. 382

12 ALLENBACH IND. 158

13 ALPHA BYTE STORAGE 31

14 ALPHA BYTE STORAGE 120,121

15 ALSPA COMP.SYS. 458

16 ALTOS COMP.SYS. 152, 153

18 AMER.COMP.&TELECOMM.265

19 AMER.COMP.EXCH. 458

17 AMER.SMALL BUSN.COMP 453

20 AMER.SQUARE COMP. 261

21 ANADEX 145

22 ANCRONA 228

23 ANDERSON JACOBSON 377

24 APPARAT INC 77

25 APPLE COMPUTER INC 12, 13

3 APPLE COMPUTER INC 12, 13

• APPLE COMPUTER INC 346

26 APPLIED SYSTEMS 422

27 ARTEC ELECTRONICS 88

28 ARTIFICIAL INT'L.RESRCH 462

29 ASAP COMP.PROD.INC. 335

30 ASAP COMP.PROD.INC. 236,237

31 ASHTON-TATE 282, 283

32 AUTOCONTROLINC452

33 AUTOCONTROL INC 452

34 AUTOMATED EQPTMNT. 357

• AVOCET14

35 B & B ELECTR. 456

36 BASF SYSTEMS 279

37 SEAMAN PORTER 269

38 BELL.JOHN ENGR. 449

• BETA COM P.DEVICES 275

39 BISON PRODUCTS 461

40 BIT BUCKET, THE 462

41 BIZCOMP253

43 BOWER-STEWART 460

44 BUSINESS OPERTING SYS 167

45 BUSINESS WEEK 341' BYTE BOOKS 249

46 BYTE BOOKS 250

47 BYTE BOOKS 251

48 BYTE BOOKS 252

• BYTE BACK ISSUES 379' BYTE WATS 377

50 CALIF DATA CORP 462

51 CALIF. DIGITAL 484, 485

52 CALIF.COMP.SYS. 21

53 CALIF.COMP.SYS. 20

54 CAMEO ELECTR.INC 233

55 CDR SYS.INC 452

137 CHATSWORTH DATA CORP 125

58 CHECK-MATE 458

59 CHECKS-TO-GO 10

60 CHIPS & DALE 454

61 CHRISLIN INDUSTRIES 323401 CINEMATRONICS 496

62 CLEV.CONS.COMP.& COMP-NTS. 467

63 CMC,INT'L220

65 COMPONENTS EXPRESS 369

66 COMPSTAT CO. 431

67 COMPUMART184, 185

151 COMPUPRO/GODBOUT 243

152 COMPUPRO/GODBOUT 244, 245

68 COMPUSERVE 291

70 COMPUTER AGE 322

71 COMPUTER AID 452

72 COMPUTER AID 452

73 COMPUTER DISC.OF AM. 270

74 COMPUTER EXCHANGE 321

75 COMPUTER FURN.& ACCSS. 30

76 COMPUTER MAIL ORDER 247

77 COMPUTER PLUS 456

78 COMPUTER SHOPPER 460

79 COMP. SPCLTIES. 100, 101

80 COMPUTER STOP, THE 465

81 COMPUTER STORE, THE 410

• COMPUTER WRHSE. 117

83 COMPUTERS ETC. 368

84 COMPUTERS ETC. 370

Inquiry No.

Page No.

85 COMPUTERS ETC. 380

56 COMP.PERIPH.UNLTD379

86 COMPUTERS WHOLESALE 390

87 COMPUTEX CORP 294

88 COMPUTIQUE 285

89 COMPUVIEW PROD.INC. 69

90 CONCOMP IND. 308

91 CONCOMP IND. 357

92 CONCORD COMP.PROD. 468

93 CONSUMER COMP. 139

94 CONSUMER COMP. 476, 477

95 CPI 298

96 CPU SHOP, THE 459

97 CROMEMCO 1. 2

98 CS 458

* CYBERNETICS INC 359

99 D & W DIGITAL 26

* DATA DISCOUNT CTR 130

* DATA GENERAL 70, 71

101 DATA HARDWARE 460

102 DATA-ED 161

103 DATALEX COMPANY, THE 318

104 DATASOUTH COMP CORP 67

105 DATASOUTH COMP.CORP. 278

106 DATATRONIC 287

395 DELTA PRODUCTS 438, 439

107 DENVER SFTW.CO., THE 151

108 DESIGNER SOFTWARE 81

109 DIGIAC CORP 351

110 DIGIBYTE SYS CORP 205

111 DIGICOMP RESRCH CORP 160

112 DIGITAL ELECT.SYS 407

113 DIGITAL GRAPHIC SYS 371

114 DIGITAL MARKETING 355

115 DIGITAL MARKETING 6

116 DIGITAL PRESS 157

117 DIGITAL RESEARCH 127

118 DIGITAL RESEARCH COMP 488,489

119 DIP INC. 353

120 DISCOUNT SFTW GRP, THE 374' DISK SUPPLY 363

121 DMA 166

122 DMA 415

123 DUAL SYS.CONTROL CORP 76

124 DUAL SYS.CONTROL CORP 78

125 DUAL SYS.CONTROL CORP 80

126 DUGGER'S GROWING SYS 458

127 DYMARC IND. 365

128 DYNABYTE BUSN.COMP. Clll

129 DYNACOMP 324, 325

130 DYSAN CORP 136, 137

131 ECOSOFT 349

132 ELECTROLABS 468

134 ELECTRONIC CONTROL 316

135 ELECTRONIC SPCLISTS 347

136 ELECTRONIC SYS.FURN 102

57 ELECTRONICS CENTER 125

138 ELLIS COMPUTING 349

139 EMPIRICAL RESRCH GRP. 456

140 EMPIRICAL RESRCH GRP. 464

141 EPSON AMERICA 299

* ESCON 373

142 EXPOTEK 393

* F.E.C.LTD. 464

* FAIRCOM417

143 FORETHOUGHT PRODUCTS 349

144 FREDERICK COMP.PROD. 367

145 FSS 460

146 FYI INC. 456

147 GIDDINGS & LEWIS 191

148 GIMIXINC362

149 GIMIXINC460

150 GNT AUTOMATIC INC 242

154 H & E COMPUTRONICS 227

155 H & E COMPUTRONICS 229

156 HANLEY ENGNRING 457

157 HAYES MICROCOMP.PROD. 63

158 HAYES MICROCOMP.PROD. 215

* HEATH COMPANY 16, 17, 207

* HEATH POSTCARD 400 A&B

159 HEMENWAY ASSOC. 319

160 HEWLETT-PACKARD 51

161 HOBBY ROBOTICS 454

162 HOUSTON INSTRUMENTS 224

163 HOUSTON INSTRUMENTS 224

164 IMS INTERNATIONAL 159

* INDEPENDENT BUS.SYS. 119

166 INFOSOFT SYSTEMS INC 286

167 INNOVATIVE PROD. 364

168 INNOVATIVE SFTW APPL 176

169 INT'LMICROSYS311

Inquiry No.

Page No.

171 INTEGRAND 345

172 INTEGRATED BUSN.COMP. 425

173 INTERACTIVE MICROWRE 210

* INTERACTIVE STRUCT. 328

174 INTERACTIVE STRUCT. 338

193 INTERTEC DATA 25

175 INTERTEC DATA SYS. 177

176 IPEX INT'L 458

177 ITHACA INTERSYSTEMS 8, 9

178 JADE COMP.PROD 471

179 JADE COMP.PROD. 472, 473

180 JAMECO ELECTR. 486, 487

181 JDR MICRODEVICES 474, 475

182 JMCA SOFTWARE 454

183 KADAK PRODUCTS 300

* KENGORE CORP. 454

184 KERN PUBLISHING 351

185 KLO-FOX 460

186 KV 33 462

1B7 LABORATORY MICROSYS. 377

188 LADCO DEVELMNT CO INC 380

189 LIFEBOAT ASSOC 263

190 LIFEBOAT ASSOC 309

191 LIFEBOAT ASSOC 213

192 LNW RESEARCH 331

194 LOGO COMP.SYS. 343

195 LOMAS DATA PRODUCTS 367

196 LYBEN COMP.SYS. 452

197 MACROTRONICS 452

198 MACROTRONICS 462

199 MAGNOLIA MICROSYS 454

200 MALIBU ELECTR CORP 143

201 MANNESMANN TALLY 413

202 MAROTSFTW.SYS.INC203

203 MARTEC 369

204 MARYMAC INDUSTRIES 373

205 MASTER ELECTR.INC 96

206 MAURO ENGINEERING 268

207 MAXTEK 32

400 MCCLINTOCK CORP 158

* MCGRAW-HILL BOOK CO 256,257

208 MCGRAW-HILL BOOK CO 350

* MCMILLAN BOOK CLUBS 305

209 MEADE'S DATA SYS 454

210 MEAS.SYS. & CONTROLS 28, 29

211 MEMORY MERCHANT 53

212 MENTOR SOFTWARE 460

213 META TECHNOLOGIES 440

214 MICRO AGE COMP.STORE 174,175

216 MICRO BUSINESS WORLD 179

217 MICRO BUSN. ASSOC 458399 MICRO BUSN. SYS 125

218 MICRO COM 147

220 MICRO DECISIONWARE 140

221 MICRO FOCUS 79

222 MICRO HOUSE 280, 281' MICRO 310

223 MICRO MANAGEMENT SYS 347348 MICRO MINT 383

224 MICRO PRO INT'L 231

225 MICRO SCI 93

226 MICRO SOURCE OF TX 466

227 MICRO WORKS, THE 365

228 MICROACE 369

229 MICROCOMP.TECH.INC173

230 MICROCOMPUTER APP. 387

231 MICROCRAFT SYS 214

232 MICRODASYS 201

234 MICROMAIL376

235 MICROMATE ELECTR.INC 345

236 MICROSOFT (CPD) 111

237 MICROTECH EXPORTS 212

238 MIKOS 466

239 MILLER MICROCOMP.SERV 288

240 MINI COMP.SUPPLIERS 357

241 MINI MICRO MART 478

242 MINI MICRO MART 479

243 MINI MICRO MART 18

244 MIRO COMPUTERS INC 375

245 MORROW DESIGNS 57

246 MOUNTAIN COMPUTER 19

247 MOUNTAIN VIEW PRESS 195

248 MPI 181

' MRD SYS INC 464

249 MSD 156

250 MTI188

251 NASHUA CORP 162

252 NAT'L DATA SUPPLIES 462

' NATIONAL COMP. SHOW 339

253 NEBS 208

254 NEEC0 295

To get further information on the products advertising in BYTE, fill out the reader service card withyour name and address. Then circle the appropriate numbers for the advertisers you select from thelist. Add an 18-cent stamp to the card, then drop it in the mail. Not only do you gain information, butour advertisers are encouraged to use the marketplace provided by BYTE. This helps us bring you a big-ger BYTE. The index is provided as an additional service by the publisher, who assumes no liability forerrors or omissions. "Correspond directly with company.

Inquiry No.

Page No.

• NETRONICS104, 106, 348

255 NORSEA DATA CORP 165

256 NORTH AMER TECH 178

257 NORTH AMER TECH 82

258 NORTHWEST COMPUTER 361

259 NOVATION 290

• NRI SCHOOLS ELECTR DIV 289

• OASIS SYSTEMS 258

260 OHIO SCIENTIFIC INSTR C IV

261 OKIDATA CORP 219389 OKIDATA CORP 221

262 OLIVER ADVANCED ENGIN 464

263 OLYMPIC SALES 363

264 OMEGA MICRO COMPUTER 421

265 OMEGA SALES 302, 303

266 OMIKRON 49

267 OMNI RESOURCES 115133 ORACLE ELECTR 456

268 ORANGE MICRO 148, 149

269 ORANGE MICRO 141

271 ORION INSTRUMENTS 464

272 OSBORNE COMPUTERS 33

273 OSBORNE WILSON LABS 332

274 OSBORNE/MCGRAW-HILL107' OWENS ASSOC 254, 255

275 PACIFIC COMP BRK 226

276 PACIFIC DISC SFTW 462

277 PACIFIC EXCHANGES 382

278 PACIFIC EXCHANGES 454

279 PACIFIC EXCHANGES 464

280 PACIFIC EXCHANGES 416

396 PACIFIC MEDIA PRODUCTS 194

281 PAGE DIGITAL 480, 481

282 PALOMAR COMP EQUIP 333

283 PAN AMERICAN ELEC INC 470

284 PAPER TRACTOR 379

285 PASSWORD DISTR 431

286 PC NEWSLETTER 382

287 PEACHTREE SOFTWARE 73' PERCOM DATA 7, 15

288 PERCOM DATA 454

291 PERSONAL COMPUTERS 272

• PETRO-LEWIS CORP 234

292 PHASE ONE SYS INC 267

293 PICKLES & TROUT 366

294 POLY PAKS 458

295 POLYLINE CORP 464

• POPULAR COMPUTING 225

296 POTOMAC MICRO-MAGIC 411

297 POWER ONE INC 163

298 PRACTICAL MGMNT SYS 462

299 PRIORITY ONE 490, 491

300 PRIORITY ONE 492, 493

301 PROTECTO ENTERPR 456

302 PURCHASING AGENT, THE 186

303 QANTEX DIV 327

304 QUALITY COMP PARTS 464

305 QUALITY COMP PARTS 84

306 QUALITY SOFTWARE 91

307 QUASAR DATA PROD INC 313

308 QUEST ELECTR 455

309 R KS ENTERPRISES INC 312

310 R.R.SOFTWARE 371

311 RACET COMPUTES 361

312 RADIO SHACK 35

313 RADIO SHACK ASSOC STR 124

314 RADIO SHACK-GLNW SPR 347

315 RADIX INC 456

316 ROBOTICS AGE 361

317 S C DIGITAL 373

318 S-100 INC 365

319 SCIENTIFIC ENGRG LABS 206

320 SCIENTIFIC SFTW PROD 458

321 SCION CORP 5

322 SCITRONICS 412

• SCOTTSDALE SYSTEMS 154

324 SCR ELECTR 464

325 SEATTLE COMP PRODS 113

326 SECURED COMP SYS 462

327 SELECT INFO SYS 293

328 SIERRA DATA SCIENCES 370

329 SLUDER 456

330 SOFTECH MICROSYS 317

• SOFTWARE ARTS 273233 SOFTWAREHOWS 65

• SOLID STATE SALES 172

332 SORRENTO VALLEY ASSOC 340

333 SOUTHERN COMP SYS 456

334 SOUTHWEST TECH PROD C II

335 SPECIALIZED BUSN SYS 375

336 SPECTRUM SOFTWARE 197

337 SSM MICRO COMP PROD 11

• STATCOM CORP 89

338 STATIC MEMORY SYS 235

339 SUBLOGIC 315

340 SUNNY INT'L 470

341 SUPER STAR INT'L 222

• SUPERSOFT 54, 99, 155, 358,378, 381

342 SURVEYOR SUPPLY CO 367

343 SYBEX 93

• SYNCHRO SOUND 334

344 SYNCTRONICS 170

397 SYNEMED, INC 109

345 SYS INTERFACE CONSUL 92

September 1981 © BYTE Publications Inc 495

Inquiry No. Page No.

Inquiry No. Page No.

Inquiry No. Page No.

Inq

jiry No. Page No.

346 SYSTEMS PLUS 189

357

THREE M COMPANY 223

368

U.S. MICRO SALES 307

•

VR DATA 363

• TAB BOOKS 337

358

THREE M COMPANY 94

369

U.S. MICRO SALES 463

381

WASHINGTON COMP SERV 469

347 TARBELL ELECTR 351

359

THREE M COMPANY 95

370

U.S. ROBOTICS 271

382

WEIGH SYSTEMS TECH 292

*

THUNDERWARE 187

371

UNIVERSAL SFTW.STUDIOS 418

•

WESTICO INC 171, 452

349 TEAM ELECTR 371

■

TINNEY.RBT.GRAPHICS 408

372

UVEON COMP SYS 27

383

WESTWARE 129

• TECHNICAL SYS CONS 199

360

TKS CORP 329

373

VAN HORN OFFICE SUPP 375

*

WHITESMITHS LTD 131

350 TECMAR INC 301

361

TNW CORP 367

374

VAN DATA 409

384

WICAT SYSTEMS 55

351 TEI, INC 61

362

TOSHIBA AMERICA INC 23

375

VECTOR ELECTR 86

385

WICAT SYSTEMS 217

352 TEI, INC 239

363

TRANSFORMATION TECH 454

376

VECTOR GRAPHICS 75

49

WILLIAMS LABS 368

353 TELERAM COMMUNC 306

364

TRANSNET CORP 345

377

VERBATIM CORP 87

386

WINTEK CORP 452

354 TELEVIDEO INC 209

365

TRANSWAVE CORP 193

378

VERTICAL DATA SYS INC 150

387

WINTERHALTER & ASSOC 326

355 TERCER MEDIO 211

366

TRINITY GRP, THE 460

390

VID EX 277

388

X COMP 297

356 TEXAS COMP SYS 204

379

VISTA COMPUTER CO 105

"

ZOBEX 83

' TEXAS INSTRUMENTS 135

367

TSE/HARDSIDE 366

380

VOTRAX 168, 169

BOMB

)naoina Monitor Box

BYTE'

sC

Article #

Page

Article

Author(s)

1

38

Build an Unlimited-Vocabulary Speech

Synthesizer

Ciarcia

2

52

The Big Board: A Z80 System in Kit

Form

Thompson

3

58

The Xerox Alto Computer

Wadlow

4

72

Tree Searching, Part 1: Basic Tech-

niques

Williams

5

112

One Step Forward—Three Steps

Backup

Stakem

6

146

Misosys Software's DISKMOD: Put

Radio Shack's Editor/Assembler on Disk

Hughes

7

150

MINCE, A Text Editor

Kern

8

164

Artificial Intelligence

Roberts

9

180

A High-Level Language Benchmark

Gilbreath

10

200

, Science Fiction's Intelligent Computers

Byrd

11

216

Symbolic Differentiation a la LISP

Nicol

12

238

Knowledge-Based Expert Systems

Come of Age

Duda,Gaschnig

13

284

The Atari Tutorial, Part 1: The Display

List

Crawford

14

304

Natural-Language Processing, The Field

in Perspective

Hendrix,Sacerdoti

15

384

BYTE's Arcade: Big Five Software; The

Prisoner

Williams,Liddil

16

368

Three Microcomputer LISPs

Levitan, Bonar

17

414

The Emperor's Old Clothes

Hoare

18

436

Interactive Fiction: Six Micro Stories

Liddil

June BOMB Speaks Out

Steve Ciarcia's "Build a Low-Cost Speech-Synthesizer Interface"has talked its way into first placethis month. Steve gets the SI00purse for his description of NationalSemiconductor's Digitalker speech-synthesis system. The article, ob-viously, left our readers speechless.The $50 second-place award goesto Gary Kildall for his article,"CP/M: A Family of 8- and 16-BitOperating Systems," whichdescribes the de facto standard"software bus." Robert Greenbergand James Larson tied for thirdplace. Greenberg's "The UNIXOperating System and the XENIXStandard Operating Environment"provided an inside look at a large-computer operating system formicroprocessors. Larson's article,"The Ins and Outs of CP/M,"clarified and expanded on in-put/output and disk interfacingwithin the CP/M environment.

GAME DESIGNERS

CINEMATRONICS, a leader in the coin-operated video game industry, is expanding its game design staff. We are seekingindividuals with the special talent for game design, exceptional creativity, and superior Assembly language programmingskills.

CINEMATRONICS offers competitive salaries, paid sick and vacation time, medical coverage, pension and profit sharing.

If you're looking for an excellent opportunity with a rapidly growing, employee conscious company, please forward yourresume to Sandra Baca, Director of Personnel:

CINEMATRONICS, INC.

1841 Friendship Drive, El Cajon, CA 92020

An Equal Opportunity Employer

496 September 1981 © BYTE Publications Inc

Circle 401 on inquiry card.

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The 5615 is the sure way to get the systemyou need. With more power for the price. Youcan select memory to 400 KB on our S-100bus architecture. Choose from 3 sizes ofWinchesters to 45 MB and have diskette back-up to your system also. If it's tape back-up youneed, then choose our 5700. If you need lessstorage, our 5lA" floppy 5200, our 8" floppy5300 or our 5400 system using both floppies,with up to 3.6 MB capacity, can be yours.

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California 94025.

Business Manager is a registered trademark of Dynabyte. CP/M and MP/M are registered trademarks of Digital Research Corp.

Circle 128 on inquiry card.

"Over 15,000 items in inventory could bea nightmare. But it's not 'cause myChallenger g*%±computer workslike a I^J dreamt

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Richard Nolan, President,Aerospace Nylok Corp.,Hawthorne, New Jersey

Ohio Scientific was first to add Winchester

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Wade Carlson,Vice President,Wally Carlson & Sons,Lindstrom, Minnesota

[//" \J 1333 SOI

a vljJI&eDtl Company

333 SOUTH CHILLICOTHE ROADAURORA, OH 44202 • [21 6] 831 -5600

Circle 260 on inquiry card.