Byte Magazine Volume 02 Number 05 - Interfacing

This book was produced in EPUB format by the Internet Archive.

The book pages were scanned and converted to EPUB format automatically. This process relies on optical character recognition, and is somewhat susceptible to errors. The book may not offer the correct reading sequence, and there may be weird characters, non-words, and incorrect guesses at structure. Some page numbers and headers or footers may remain from the scanned page. The process which identifies images might have found stray marks on the page which are not actually images from the book. The hidden page numbering which may be available to your ereader corresponds to the numbered pages in the print edition, but is not an exact match; page numbers will increment at the same rate as the corresponding print edition, but we may have started numbering before the print book's visible page numbers. The Internet Archive is working to improve the scanning process and resulting books, but in the meantime, we hope that this book will be useful to you.

The Internet Archive was founded in 1996 to build an Internet library and to promote universal access to all knowledge. The Archive's purposes include offering permanent access for researchers, historians, scholars, people with disabilities, and the general public to historical collections that exist in digital format. The Internet Archive includes texts, audio, moving images, and software as well as archived web pages, and provides specialized services for information access for the blind and other persons with disabilities.

Created with abbyy2epub (v.1.7.0)

Old Fashion MLGD

in the

Our 6800 computer system repre-sents the best value available today,with no sacrifice in performance.

I would like to explain why this istrue. The most basic reason is thatthe 6800 is a simpler, more elegantmachine. The 6800 architecture ismemory oriented rather than busoriented as are the older 8008, 8080and Z-80 type processors. This is animportant difference. It results in acomputer that is far easier to programon the more basic machine languageand assembly language levels. It alsoresults in a far simpler bus structure.The 6800 uses the SS-50 bus whichhas only half the connections neededin the old S-100 (IMSAI/MITS) bussystem. If you don't think this makesa difference, take a look at the motherboards used in both systems—com-pare them. The SS-50 system haswide, low impedance 0.1 lines withgood heavy, easily replaced Molexconnectors. The S-100 bus, on theother hand, has a very fine hair-likelines that must be small enough topass between pins on a 100 contactedge connector. I'll give you oneguess which is the most reliable andnoise free. As for cost—well any of

BSffii 68DO 85SS-

you who have purchased extra con-nectorsfor your S-1 00 machines knowwhat kind of money this can runinto. The 6800 is supplied with a_Hmother board connectors. No extras,or options like memory, or con-nectors for the mother board areneeded in our 6800 system.

The 6800 is not beautiful, but "OhBoy" is it functional. That plainblack box is strong and it has anannodized finish. This is the hardest,toughest finish you can put on alu-minum. Most others use paint, orother less expensive finishes. The6800 does not have a pretty frontpanel with lights and multicolor swit-ches. This is because the lights andswitches are not only expensive, andunnecessary, but also a great big painto use. We don't crank up the 6800;we use an electric starter—a monitorROM called Mikbug. He automatical-ly does all the loading for you with-out any time wasting switch flopping.So in the 6800 system you don't buysomething expensive (the console)that you will probably want to stopusing as soon as you can get yourhands on a PROM board and a goodmonitor.

Tradition

That's another thing. Mikbug® is astandard Motorola part. It is used inmany systems and supported by theMotorola software library in additionto our own extensive collection ofprograms. It is not an orphan likemany monitor systems that are uni-que to the manufacturer using themand which can only run software pro-vided by that manufacturer. Checkthe program articles in Byte, Interfaceand Kilobaud. You will find that al-most all 6800 programs are writtenfor systems using a Mikbug® monitor.Guess how useful these are if youhave some off-brand monitor in yourcomputer.

The 6800 will never win any beautyprizes. It is like the Model "T" andthe DC-3 not pretty, but beautifulin function. It is simple, easy to useand maintain and does its job inthe most reliable and economical waypossible. What more could you want?

Mikbug ® is a registered trademarkof Motorola Inc.

(§©©©

Computer System

with serial interface and 4,096 wordsof memory $395.00

□ Enclosed is $395 for my SwTPC Computer Kit □ Send Data

□ or BAC #

□ or MC Ex Date

ADDRESS

CITY STATE. ZIP

Southwest Technical Products Corp., Box 32040, San Antonio, Texas 78284

Meet the most powerfuljjlC system available for dedicated work.

Yet it's only $595:

Here's the muscle you've been telling us you wanted:a powerful Cromemco microcomputer in a style and pricerange ideal for your dedicated computer jobs—ideal forindustrial, business, instrumentation and similar applica-tions.

It's the new Cromemco Z-2 Computer System. Here'ssome of what you get in the Z-2 for only $595:

• The industry's fastest ,uP board (Cromemco's highlyregarded 4 MHz, 250-nanosecond cycle time board).

• The power and convenience of the well-known Z-80MP.

• A power supply you won't believe ( + 8V @ 30A,+ 18V and — 18V @ 15A — ample power for addi-tional peripherals such as floppy disk drives).

• A full-length shielded motherboard with 21 card slots.

• Power-on-jump circuitry to begin automatic programexecution when power is turned on.

• S-100 bus.

• Standard rack-mount style construction.

• All-metal chassis and dust case.

• 110-or 220-volt operation.

DEDICATED APPLICATIONS

The new Z-2 is specifically designed as a powerful buteconomical dedicated computer for systems work. Noticethat the front panel is entirely free of controls or switchesof any kind. That makes the Z-2 vir-tually tamper-proof. No accidentalprogram changes or surprise mem-ory erasures.

FASTEST, MOSTPOWERFUL fiC

Cromemco's microcom-puters are the fastest andmost powerful available.They use the Z-80 mi-croprocessor which is

widely regarded as the standard of the future. So you'rein the technical fore with the Z-2.

BROAD SOFTWARE/PERIPHERALS SUPPORT

Since the Z-2 uses the Z-80, your present 8080 soft-ware can be used with the Z-2. Also, Cromemco offersbroad software support including a monitor, assembler,and a BASIC interpreter.

The Z-2 uses the S-100 bus which is supported by theperipherals of dozens of manufacturers. Naturally, allCromemco peripherals such as our 7-channel A/D andD/A converter, our well-known BYTESAVER with itsbuilt-in PROM programmer, our color graphics interface,etc., will also plug into the S-100 bus.

LOW, LOW PRICE

You'll be impressed with the Z-2's low price, technicalexcellence and quality. So see it right away at yourcomputer store—or order directly from the factory.

Z-2 COMPUTER SYSTEM KIT (MODEL Z-2K) (includes4 MHz ji.? card, full-length 21-card-slot motherboard,power supply, one card socket and card-guide set, andfront panel; for rack mounting) $595.

Z-2 COMPUTER SYSTEM ASSEMBLED (MODEL Z-2W)(includes the above as well as ail 21 sockets and cardguides and a cooling fan; for rack mounting )... $995.

TV DAZZLER

T

To makeyour computer

more useful-

a wide choice of

memory, I/O, CPU

Your computer's usefulness de-pends on the capability of its CPU,memories, and I/O interfaces, right?

So here's a broad line of trulyuseful computer products that letsyou do interesting things with yourCromemco Z-1 and Z-2 computers.And with your S-100-compatible Al-tairs and IMSAIs, too.

CPU

• Z-80 MICROPROCESSOR CARD.The most advanced /xP card avail-able. Forms the heart of our Z-1and Z-2 systems. Also a direct re-placement for Altair/IMSAI CPUs.Has 4-MHz clock rate and the powerof the Z-80 fxP chip. Kit (Model ZPU-K): $295. Assembled (Model ZPU-W): $395.

MEMORIES

• 16K RAM. The fastest available.Also has bank-select feature. Kit(Model 16KZ-K): $495. Assembled(Model 16KZ-W): $795.

• 4K RAM. Bank-select allows ex-pansion to 8 banks of 64K byteseach. Kit (Model 4KZ-K): $195. As-sembled (Model 4KZ-W): $295.

• THE BYTESAVER —an 8K capa-city PROM card with integral pro-

grammer. Uses high-speed 2708 eras-able PROMs. A must for all com-puters. Will load 8K BASIC into RAMin less than a second. Kit (ModelBSK-0): $145. Assembled (ModelBSW-0): $245.

• 16K CAPACITY PROM CARD. Ca-pacity for up to 16K of high-speed2708 erasable PROM. Kit (Model16KPR-K): $145. Assembled (Model16KPR-W): $245.

I/O INTERFACES

• FAST 7-CHANNEL DIGITAL-ANALOG I/O. Extremely usefulboard with 7 A/D channels and 7D/A channels. Also one 8-bit par-allel I/O channel. Kit (Model D +7A-K): $145. Assembled (Model D+ 7A-W): $245.

• TV DAZZLER. Color graphics in-terface. Lets you use color TV as full-color graphics terminal. Kit (ModelCGI-K): $215. Assembled (ModelCGI-W): $350.

• DIGITAL INTERFACE (OUR NEWTU-ART). Interfaces with teletype,CRT terminals, line printers, etc. Hasnot one but two serial I/O ports andtwo 8-bit parallel I/O ports as wellas 10 on-board interval timers. Kit

(Model TRT-K): $195. Assembled(Model TRT-W): $295.• JOYSTICK. A console that letsyou input physical position data withabove Model D + 7 A/D card. Forgames, process control, etc. Con-tains speaker for sound effects. Kit(Model JS-1-K): $65. Assembled(Model JS-1-W): $95.

PROFESSIONAL QUALITY

You get first-class quality withCromemco.

Here are actual quotes from ar-ticles by independent experts: "TheCromemco boards are absolutelybeautiful" . . . "The BYTESAVER istremendous" . . . "Construction ofCromemco I/O and joystick are out-standing" . . . "Cromemco periph-erals ran with no trouble whatso-ever."

Everyone agrees. Cromemco istops.

STORES/MAIL

So count on Cromemco. Lookinto these Cromemco products atyour store. Or order by mail fromthe factory.

We wish you pleasure and suc-cess with your computer.

Q CromemcoincorporatedSpecialists in computers and peripherals2432 CHARLESTON RD., MOUNTAIN VIEW, CA 94043

(415)964-7400

In the Queue

KITE MAY 1977

Volume 2Number 5

1734566298132136

26507684

Foreground

A CATALOG OF LIBERATING HOME COMPUTER CONCEPTS

Speculations—LauTHE APPLE-II

System Description—WozniakINTERFACING WITH AN ANALOG WORLD-Part 1

Peripherals—CarrWHAT'S IN A FLOATING POINT PACKAGE?

Software—LinkerA GUIDE TO BAUDOT MACHINES: Part 2

Interfaces-McNattALL THIS JUST TO PRINT A QUOTATION MARK?

Software—Chapman8080 PROGRAMMING NOTES

Software—Krystosek-McCarty

Background

ARTIFICIAL INTELLIGENCE, AN EVOLUTIONARY IDEA: Part 1

Software—WimbleCOME UPSTAIRS AND BE RESPECTABLE

Hardware—CiarciaUSING A KEYBOARD ROM

Hardware—BrehmIMPLEMENTING THE TINY ASSEMBLER

Software—Emmerichs

Nucleus

4

6

10

46,121, 14368, 142116,127,152117120

In This BYTESurveying the FieldLettersWhat's New?Technical ForumBYTE's BitsNew ASCI I StandardsClassified Ads

128 BYTE'S Bugs

145 Solution to 8080 Bug in the Stack

145 Answer to Bar Code Puzzle

146 Book Reviews148 Ask BYTE

156 Clubs, Newsletters

176 BOMB

176 Reader Service

BYTE is published monthly by BYTE Publications Inc. 70 Main St, Peterborough NH 03458.

Address all mail except subscriptions to above address; phone (603) 924-7217. Address all

editorial correspondence to the editor at the above address. Unacceptable manuscripts will be

returned if accompanied by sufficient first class postage. Not responsible for lost manuscripts or

photos. Opinions expressed by the authors are not necessarily those of BYTE. Address all

subscriptions, change of address, Form 3579, and fulfillment complaints to BYTE

Subscriptions, PO Box 361, Arlington MA 02174; phone (617) 646-4329.

Second class postage paid at Peterborough NH 03458 and at additional mailing offices.

Subscriptions are $12 for one year, $22 for two years, and $32 for three years in the USA and

its possessions. Add $5.50 per year for subscriptions to Canada and Mexico. For air delivery to

western Europe, and for surface delivery worldwide, $25 for a one year subscription only.

Worldwide air delivery available at additional rates upon request.

Single copy price is $1.50 in the USA and its possessions, $2 in Canada and Mexico, and $3

elsewhere.

Foreign subscriptions and sales should be remitted in United States funds. Printed in United

States of America. Entire contents copyright © 1977 by BYTE Publications Inc. All rights

reserved.

PUBLISHERS

Virginia Peschke

Manfred Peschke

EDITOR IN CHIEF

Carl T Helmers Jr

PRODUCTION MANAGER

Judith Havey

CIRCULATION MANAGER

Manfred Peschke

ASSISTANT PUBLISHER

Debra Boudrieau

EDITOR

Christopher P Morgan

CO-OP EDITOR

Scott Morrow

PRODUCTION EDITOR

Karen Gregory

EDITORIAL ASSISTANT

Carol Nyland

SUBSCRIPTIONS

Kimberly Barbour

Cheryl Hurd

Deborah R Luhrs

DEALER SALES

Ginnie F Boudrieau

ADVERTISING

Elizabeth Alpaugh

Debra Boudrieau

Virginia Peschke

CLUBS, PAPERBYTES

Peter Travisano

TRAFFIC MANAGERS

WaiChiu Li

Gregory Spitzfaden

ART

Noreen Bardsley

Mary Jane Frohlich

Ellen Shamonsky

SPECIAL PRODUCTS

Susan Pearne

Floyd Rehling

DRAFTING

Lynn Malo

Bill Morello

Stephen Kruse

TYPOGRAPHY

Custom Marketing Resources Inc

Goodway Graphics

PHOTOGRAPHY

Ed Crabtree

PRINTING

The George Banta Company

Custom Marketing Resources Inc

EDITORIAL CONSULTANT

Daniel Fylstra

ASSOCIATES

Bob Baker

Walter Banks

Steve Ciarcia

David Fylstra

Portia Isaacson

Harold A Mauch

AFFILIATE PUBLISHER

Southeast Asian Editions

John Bannister

= y

"""A

XX

£s

^'""tf/%/%, g^B^LfHuniuiiiiinnniiininiiniiiiniiiiuiiiiiiiiiniii

InThis

j^

S ^^

page 84

Ideas and imagination are theinputs to creative uses of computers.Ted M Lau has set down some of histhoughts on potential personalizeduses of computers in his Catalog ofLiberating Home Computer Concepts.Some of his suggestions can be imple-mented with present technology.Some will have to await further de-velopment. In either case the prospectsare exciting.

Artificial intelligence has intriguedpeople for many years. The possibilitythat computers may be able to "thinkon their own" is one of the recurringthemes of science fiction. Artificialintelligence is starting to pervade re-ality, not the super thinking beasts offiction, but the machines that performtasks normally thought to require in-telligence. In his article, Artificial In-telligence, an Evolutionary Idea,Michael Wimble describes one type ofartificial intelligence technique whichreaders may find quite useful.

What does it take to make acomputer system complete to thepoint of plugging it into the wall,plugging it into a color television, andturning it on? Stephen Wozniak ofApple Computer describes the designof such a system in his productdescription article on the Apple-!I.

BITE

Now that you have your micro-processor up and running you surelywant to parade it before some of yourfriends and relatives. Your clutteredbasement or garage workshop, how-ever, may not be the best place todemonstrate your brainchild. In hisarticle, Come Upstairs and Be Respect-able, Steve Garcia describes his solu-tion to this dilemma by installing aremote keyboard and video monitor inhis den. This arrangement is great forparties and other gatherings since thevital components of the processor can-not be subjected to the whims of someunknowledgeable person.

Joseph | Carr, in his first of a twopart article on Interfacing With anAnalog World, gives us an insight intotransducers and some of the problemsof processing their outputs into signalswhich can be digiti/ed by an analog todigital converter.

Adding floating point calculationabilities to your microprocessor canrepresent a quantum leap forward inperformance. The floating point func-tions discussed by Sheldon Linker inhis article, What's in a Floating PointPackage?, will allow you lo performaddition, subtraction, multiplicationand division with extremely large orsmall numbers, using software exclu-sively.

How can you convert one of thosesurplus keyboards without encodersinto a usable text input? Find out byreading Bob Brehm's Using a Key-board ROM.

About the Cover

Birgit Quednau, a student of bio-medical technique at the university inGiessen, Germany, who is interested insmall computer systems and batik,combined both fascinations to pro-duce this month's cover, anotherwinning entry in BYTE's ComputerArt Contest.

jack Emmerichs' Tiny Assemblerpresentation is completed in thesecond part of his article in this issue:Implementing the Tiny Assembler.Readers will find a discussion of struc-tured code details for a 6800 as well ascomplete object code and sufficientinformation to get Tiny Assembler6800 up and running in any machinewith MIKBUG and at least 4 K ofmemory starting at address 0000.

Last month Michael S McNatl de-scribed the various types of Baudotteleprinters that are available on thesurplus market today. This month hedescribes various ways in which thesedevices can be interfaced to a micro-processor using both hardware andsoftware techniques in his article, AGuide to Baudot Machines: Part 2,Interfacing Techniques.

Using someone else's interpreter orcompiler is the normal mode of opera-tion for anyone contemplating a highlevel language. But with any com-plicated piece of software, usesometimes requires a bit of ingenuityon the part of the user as DavidChapman points out in his descrip-tion of a nil in many a BASIC inter-preter. Turn lo All This Just to Printa Quotation Mark? You'll also finda short glossary including some veryimportant terms in the world ofapplications software.

The 8080 microprocessor generallyperforms operations using 8 bit words.There are, however, several ways inwhich 16 bit words can be manipu-lated on the 8080. In the article, 8080Programming Notes, John McCartyand Paul Krystosek elucidate on 16 bitdata manipulation.

"A mess of parts doth not a computer make"

ANON

' 4«

,,,.'ill...MMM.I.

Undoubtedly anon was talkingabout some of today's PC computers.Exciting as they may be, most of themgive you a few surprises you really don'tneed.

Fbr example you have the board allwired, and suddenly it occurs to you,"Where's the TV interface?"

Surprise! (The TV interface is extraand costs $200 plus.)

"And the keyboard interface —where's that?"

Surprise! (Add another $185 extra.)

"How about an audio cassette inter-face so you can store and enter low costprograms and large amounts of data?"

Surprise! (Add $175 more.)

"And what about software?"

Surprise! (Each program will costyou $20 plus.)

See what we mean?

The new Sol PC Terminal Com-puter. It's a complete kit, hardware,software and no surprises for $475.

It's the first small computer con-ceived as part of a total system.

Not only do you get everything youneed, but our systems approach is moreeconomical, too. The $475 kit (fully as-

sembled and tested, $745) includes all ofthe following as standard features:

Video display interface.

Keyboard interface.

Audio cassette interface.

8080 microprocessor.

512 eight bit bytes of PROM on

a plug-in personality module.

2048 eight-bit words of RAM.

A 1024 character video display

generator.

Serial and parallel interfaces for

connection to external devices and

an edge connector for memory

expansion.

Optional extras include a powersupply, video monitor, ASCII keyboard,walnut case, floppy disk system, highspeed paper tape reader, PROM pro-grammer, and color graphics interface.We also have a library of low cost soft-ware that's the best and most extensivein the industry.

In short, you get a complete,powerful, small computer and smartterminal that's fully expandable to a largerSol system, as your requirements grow.

Surprises are great at Christmas-time. But when you're opening the box

of your new computer kit, you wanteverything you need to be there.

And with Sol, it is.

To order or to get more informa-tion write Processor Technology, 6200Hollis St., Box B, Emeryville, CA 94608.(415) 652-8080.

rifii^^^s

The

Sol PC Terminal

Computer

Editorial

Surveying the Field

By Carl Helmers

Who Uses Personal Computers?

In the fall of 1976 Mike O'Brian, who is asecond year student in the MBA program ofthe Tuck School at Dartmouth College,approached us with the idea of doing areader survey of BYTE's circulation as anindependent study project. For those amongour readers who contemplate starting amagazine (or any other business for thatmatter) you should be aware of one fact:

Table I: An estimate of the total dollar volume to date of memory andprocessor sales at the retail level, based upon a typical current price of $42per 1024 bytes of memory installed, 78,000 current demonstrated enthusiastsreading BYTE magazine, and an extrapolated total of 26,100 operatingcomputer systems with greater than 1024 bytes of memory.

Installed DollarMemory Percentage Extrapolated Volume Range

Range Count (1448 base) Installed Count (@ $42/1024 bytes)

1 K-2 K 59 4.1% 3200 $ .13Mto$ .27M

3 K-4 K 62 4.3% 3300 $ .42M to $ .55M

5 K-8 K 80 5.5% 4300 $ .90M to $ 1.45M

9K-12K 71 4.9% 3800 $ 1.44Mto$ 1.92M

13K-16K 70 4.9% 3800 $ 2.08M to $ 2.56M

17 K-24 K 62 4.3% 3300 $ 2.36M to $ 3.33M

25 K-32 K 41 2.8% 2200 $ 2.31 M to $ 2.96M

33 K-65 K 31 2.1% 1700 $ 2.36M to $ 4.64M

66 K and up 9 0.6% 500 $ 1,39M to $ 1.39M*

Total owners of operating computer systems

with 1 K or more bytes of programmable

memory 26,100 $13.4M to $1 9.1 M

Allowing a conservative range of $1000 to$1500 for processor, video interface, key-board and other peripherals at the retail level $26.1 M to $39.2M

Estimated total dollar volume to date $39.5M to $58.3M

'We have no upper bound on this range, so the lower bound is used for these estimates.

Table 2: Experience with the machine language or assembly language of

specific computers or classes of computers. Percentages calculated on a 1448response base.

Category Counts Percent

Any large computer 739 51%

Any minicomputer 849 59%

Motorola 6800 338 23%

MOS Technology 6502 163 11%

Intel 8080 607 42%

Zilog Z-80 114 8%

Intersil IM6100 67 5%

Digital Equipment L8I-11 185 13%

RCA 1802 59 4%

Signetics 2650 35 2%

National PACE 62 4%

There are so many things to be done whichare never anticipated until you get into theproject that priorities have to be made andvarious "neat" ideas put off on occasion.This reader survey task is one such "neat"thing to do from our point of view, but oflower priority than such obvious high pri-ority items as preparing the magazine once amonth, attending to circulation matters, etc.As a result, the idea had languished. WhenMike made his suggestion that we fund themailing and printing and administrative costswith he himself providing the statisticalanalysis and data reduction for his coursework through facilities at Dartmouth, theresponse was somewhat predictable: We nowhad a way to do a survey.

The results of this survey are now avail-able, and I feel that readers may be inter-ested in learning just what we found, insummary form. (A more complete paperdiscussing these results in more detail waspresented by me at the IEEE Electro 77show in New York City, April 19 1977.) I'veheard numerous rumors and conjecturesfrom various sources concerning both thenumber of computer systems already sold,the number of people involved, and the typeof people involved. But a conjecture basedon a personal assessment of the marketplacecan sometimes be no better than an arbitraryassertion. One way to change such assertionsinto a better estimate of reality is to makeempirical measurements of the data such aswe have performed. With this spirit ofmeasurement and observation, Mike and Iset out to design and implement a survey ofthe readers of BYTE, circa October-November 1976.

The basic idea of a survey is to choose asubset of the total population of readers,then mail them a detailed questionnaire tocharacterize various aspects of their partici-pation in the field of personal computing.Then, since we presume that the sampledpopulation is typical of the total population,we can generalize the results to the entire setof BYTE readers. Mike and I designed a 4page detailed questionnaire covering numer-ous aspects of the personal computing field,which was sent to an "every nth" sample ofthe BYTE circulation list as it stood the firstweek of October 1976. By selecting onlythose subscribers who had paid in full, andapplying an every nth name algorithm, weprinted a list of 2163 subscribers who wouldreceive the survey. The survey questionnaire,

a prepaid postal reply envelope, and a coverletter were sent to each of these readers. Thecover letter also contained an entry blankfor an incentive contest with five life sub-scriptions to BYTE awarded.

The survey forms were kept separatefrom the entry blanks to preserve anonymityof the respondents, and the forms were sentto Mike at Dartmouth to be keystroked andanalyzed. The response rate to this surveywas nothing short of fantastic, according toMike's marketing advisors at Dartmouth.1448 of the 2163 people surveyed returnedforms by the November 13 1976 deadline.This is a 67% response.

There are numerous ways to describecharacteristics of individuals, based on vari-ous biological, educational and economicfactors. One parameter which is of interestin passing is the question of sex. It isfashionable in this era to minimize differ-ences in interests, tastes (and therefore,capabilities) among people based on bio-logical gender. Popular illusions to the con-trary, it is an observed data point in oursurvey that 99% of the computer enthusiastsare male, 1% female. (These percentages arebased on those who answered the questions;those who ignored the question were at the1% level also.) This draws no conclusionsconcerning the reasons for the skew relativeto the total population distribution amonghuman beings on this planet, but it is aninteresting point of fact.

Another question often asked is that ofeducational level. What kind of intellectualcapabilities are demonstrated by those whoget into the computer passion as readers ofBYTE and practitioners of these arts? Weasked readers what was the highest level offormal education attained or actively inprogress. The following table summarizes theresponses found:

High school

11%

Junior college

15%

Bachelor's degree

41%

Master's degree

22%

PhD

9%

MDor DDS

2%

No answer to query

1%

This shows a definite concentration ofpeople with a significantly high educationalbackground, which of course is consistentwith the economic question "What is yourincome?" which obtained the followingresults:

$ 0to$10k

8%

$10k to $ 15k

19%

$ 15k to $20k

22%

$20k to $25k

16%

cing an 8k ramhat gives yout more versatility-lot less money!

The new MB6A "Blue Board" is compatible with Altair,IMSAI and other S-100 bus systems.

Look at these features:

• Low power—500 NS access—no wait cycle.

• DIP switch selection of memory protect increments(256, 512, 1k, 2k, 4k, or 8k).

• Provision for battery back up.

• Plus Tl low profile sockets, gold-plated edgeconnectors, solder masked, first line parts andguaranteed for 90 days.

$265.00 in easy-to-assemble kit form Includes completedocumentation and assembly instructions. $325.00 assembled.

The MB6A is available off-the-shelf through your computerhobbyist stores or direct, along with our other fine productsincluding processor, memory, I/O, mother and extender boards.

r~N J[)(P^r^[nrT~l A Diviaionof Solid State Music

2102A Walsh AvenueSanta Clara, CA 95050Telephone (408) 246-2707

LVe're the blue boards.

THE PERFECT MICROCOMPUTER

VECTOR 1

W^6,WlCmt

fe/ECCO^

■ ■

i

It's a two touch affair

VECTOR 1 is based on the 8080A Microprocessor and S-100 Bus -EASY TO ASSEMBLE, EASY TO ACCESSORIZE. EASY TO BUY AND VERY EASY TO OPERATE.

cuo=* (raphc inc.

717 LAKEFIELD ROAD, SUITE FWESTLAKE VILLAGE, CA 91361 • (805) 497-0733

$25k to $30k$30k and up

15%19%

The median income of this sample is $20kper annum, leading to the conclusion thatcomputer hackers tend to be fairly well offeconomically.

What Have People Invested So Far?

Buying a computer system is in somerespects like buying a house or a car. It is along term capital investment by the indi-vidual, but it does have characteristics unlikethe house or the car in its relative freedomfrom maintenance due to its preponderanceof integrated circuits. In designing the sur-vey, we made one mistake in the form'slayout which prevented an easy tabulationof answers in the "How much have youspent on X?" category where X is some itemlike a floppy disk, main frame, terminal, etc.But we did get useful data on a key itemwhich enables us to deduce a lower limit ontotal sales of computer products to date.This item is the number of bytes of memorycontained in systems. We found that 35% ofthe readers had operating computer systems,based on one question. Correlating the re-sponses to the question "How much mem-ory do you have in thousands (K) of bytes?"

Table 3: Language and programming experience and intentions. Allpercentages based on 1448 respondents.

Frq

Occ

Lit

Frq = frequent use, currently.

Occ = occasional use, or past use frequently.

Lit = literacy = Frq + Occ (ie: know language).

Int = intend to learn language.

None = no interest in language.

Excl = exclusions, did not answer question.

with those readers who had operating com-puter systems, we found the distribution oftable 1. This table also contains an extrapo-lated figure based upon the February 1 1977BYTE circulation of 78,000 readers, and anestimated dollar volume of sales of memory

Int

None

Excl

Machine Language

26%

40%

66%

14%

17%

3%

Assembly Language

31%

34%

65%

18%

13%

3%

BASIC

21%

38%

59%

25%

14%

2%

FORTRAN

26%

43%

69%

11%

18%

2%

PL/I

6%

13%

19%

19%

54%

8%

ALGOL

3%

13%

16%

10%

66%

8%

COBOL

8%

15%

23%

11%

58%

8%

APL

3%

10%

13%

20%

59%

8%

RPG

2%

8%

10%

9%

73%

8%

Ded Appl Lang

12%

19%

31%

12%

48%

9%

Definitions:

Continued on page 155

IN WIRE-WRAPPING (ojc) HAS THE LINE..

HOBBY-WRAP-30 wire-wrapping, stripping, unwrapping tool for awg 30 (-025 square post)

NOSTALGIA OF COMPUTING

The letter from Don Nyre in yourFebruary 1977 issue suggesting that wedo more to preserve our computerheritage by preserving antique computersand publishing more articles on com-puter nostalgia and antique computerscaught my eye. We here at WesternWashington State College are doing ourbit (?) to preserve our computer heritageby still running an IBM 7090 and canni-balizing a 7094 for parts. Yours truly cuthis eye teeth on a Royal McBee LGP-30and was weaned to an IBM 650 and fromthence to an IBM 704 in graduateschool.

Our 7090 is interfaced to our IBM360/40, which is interfaced to one ofour Interdala 7/32 minicomputers,which will shortly be interfaced to aMITS 680b. I suppose we should com-plete the circle by having the 680b pushthe START button on the 7090 console.In Seattle 709 and 7090 equipment isstill the basis of Herb Burke's PugetSound Computer Service. Interestedreaders are invited to ship their spareIBM 700 and 7000 series computers toHerb, COD. I am sure he will appreciateit.

Keep up the good work with BYTE.

Melvin Davidson

Curator, Computer Museum

Western Washington State College

Bellingham WA 98225

ANYONE HAVE A 6800 APL?

Include me in your list of BYTEreaders interested in the APL program-ming language. I would gladly buy up aproduct that made it possible to runAPL programs on my 6800 system.

Jay Voral

279 Twinlakes Dr

Sunnyvale CA 94086

ATTENTION AUTHORS:INFORMATION NEEDED

I wish your magazine and others likeit would give more coverage to com-mercial equipment and software, andhow those can be interfaced with thehome market products you primarilyfocus on. The reason is that much ofwhat you do cover appears to be usefulfor the same applications businesses and

professional institutions use their com-puters for, but at astonishingly lowercosts. Yet it remains puzzling how thishome market equipment can be usedwith commercial products.

For example, the IBM 5100 desk topcomputer appears equivalent in capacityto the Altair and similar systems for thehome; yet I, at least, find no mention ofit in BYTE. /See BYTE December 1975for a new product item on the IBM5100... CH/ At the same time, verysophisticated software is marketed forthe IBM 5 100, such as applicationspackages in APL. Can any of that soft-ware be used by the amateur computerowner?

Another example is cassette re-corders. I use some remote terminals fortimesharing for which there are cassetterecorders typically costing $3,000. Theseare the only recorders the terminal sup-pliers provide for their terminals. Is thereany way all those cassette devicescovered in BYTE can be used with thecommercial grade remote terminals,which are themselves special purposemicroprocessors (eg: GE Terminettes)?

A related example is modems. Youhave covered a variety of remote tapedata transceiver devices, but never men-tion specifically what kind is required tooperate by telephone a commercial time-sharing facility as opposed to a user'sown custom designed system.

George Lyons

280 Henderson St

Jersey City NJ 07302

API. in micro/and is alive and well;we know of several interpreters presentlyunder development, and we are pre-paring a number of articles on thesubject of implementing and using APL.With an APL interpreter for an 8080,6800, 9900 or other processor, it will bepossible to run public domain APLapplications puckages, of course allowingfor detail differences between inter-preters whicli will always exist. Yout-other queries might make good startingpoints for articles; so, author's take note.

ADDENDUMS TO THE F8 REVIEW

I would like to make a few additionsto the article on the Fairchild F8 (Febru-ary 1977, page 88). As correctly pointedout by Mr Baker, the 3851 programstorage unit (PSU) is rather expensive for

the hobbyist. But Fairchild now makes a3861 peripheral input output (PIO) chip.The PIO is identical to the PSU except itdoes not contain the 1 K of ROM. Fiveversions of the 3861 are available, eachmask programmed svith different IO portaddresses and interrupt vectors. Thischip allows for adding IO ports to asystem without adding more ROM. A3861 is about half the price of a 3851.Thus using a 3850, I to 4 3861s, a 3852DMI or 3853 SMI and PROM or pro-grammable memory, one can build acomplete system without having a 3851mask programmed. We have done thathere in a number of projects with muchsuccess.

Fairchild also makes a 3851 pro-grammed with a debug program (calledFairbug) and some Teletype IO sub-routines (part number 3851 A). Fairbugallows one to read and write memoryand the 64 scratchpad registers and loadand dump programs, as well as execute aprogram. The IO subroutines do all theserializing and timing in software. Twobits of an IO port on the 3851 A are usedfor serial input and serial output respec-tively. Two other bits are used to selectthe bps rate (110 or 300). This makes itvery easy to hook up a terminal to theF8. No UART or bps rate generator isneeded.

I think you are publishing an excel-lent magazine. Each month BYTE getsbigger and the articles get better. I'minterested in both hardware and softwareand you have a very good mix of both.I'm glad to hear that you will be runninga series of articles on building a com-puter using the 6502. I have been usingthis processor in my home system sinceit first came out. I believe it has one ofthe best instruction sets of the availableprocessors. I hope your articles willgenerate more interest in the 6502 so wecan build up a large library of softwarefor it.

Jeffry L Parker

Fairchild Systems Tech

1 725 Technology Dr

San Jose CA 95110

STANDARD TAPE INTERFACES?

A lot of data which would be inter-esting to process with amateur com-puters is distributed at cost by thefederal government in machine proc-essible form (such as the populationcensus). However, the data comes onhalf inch tape for mounting on a large-scale system. Is there any way to readthese tapes into an Altair size system?

Jacob Schmidt

310 E 83 St

New York NY 10021

Yes: Build a controller to interface asurplus 7 or 9 track tape drive. This is adoable project which has already beensuccessfully tackled by advanced home-brewers. Eventually we should see suchcontrollers available on the market asspecially items; however, the cost of 7 or

10

The POLY 88

Microcomputer

System

PolyMorphic Systems now offers the complete, assembled, per-sonal computer system—the POLY 88 System 16. A full 16K sys-tem with high speed video display, alphanumeric keyboard, andcassette program storage. A BASIC software packageproviding the most advanced features available in thepersonal computing market. Features like PLOT and TIME, which utilizeour video graphics and real-time clock. Others like VERIFY, so that you know your tape isgood before you load another. Or input type-ahead so you can tell your program to runwhile the tape is still loading (it stores up to 64 characters of commands or question responses to be executed). All theseplus a complete package of scientific functions, formatting options, and string capabilities. With the POLY 88 System 16you can amaze your timesharing friends the very first night!

PolyMorphic Systems 11K BASIC

Size: 11K bytes

Scientific Functions: Sine, cosine, log, exponential, square root, random number, x to they power.

Formatted Output • Multi-line Function Definition • String Manipulation and StringFunctions • Real-Time Clock • Point-Plotting on Video Display • Array dimensionslimited by memory • Cassette Save and Load of Names Programs • Multiple State-ments per Line • Renumber • Memory Load and Store • 8080 Input and Output • IfThen Else • Input type-ahead.Commands: RUN, LIST, SCR, CLEAR, REN, CONT.

Statements: LET, IF, THEN, ELSE, FOR. NEXT, GOTO, ON. EXIT, STOP, END, REM,READ, DATA. RESTORE, INPUT, GOSUB, RETURN, PRINT, POKE, OUT.Built in Functions: FREE, ABS. SGN, INT. LEN, CHR$, VAL, STR$, ASC, SIN, COS, RND,LOG. TIME. WAIT, EXP, SORT. CALL, PEEK, INP, PLOT.

Systems Available. The POLY 88 is available in either kit or assembled form. It is suggest-ed that kits be attempted only be persons familiar with digital circuitry. The following are twoof the systems available.

System 2: is a kit consisting of the POLY 88 chassis, CPU, video circuit card, and cassetteinterface. Requires keyboard, TV monitor, and cassette recorder for operation. $690System 16: consists of an assembled and tested System 2 with 16K of memory, keyboard,TV monitor, cassette recorder. 11K BASIC and Assembler on cassette tapes. $1995.

Prices and Specifications subject to change without notice.California residents add 6% sales tax.

PolyMorphicSystems

460 Ward Drive Santa Barbara,Ca. 93111 (805) 967-2351

9 track IBM compatible drives is fairlyhigh unless purchased via a surplushouse.

6800 REGISTER TRANSFERS,CLARIFIED

Many readers must have spotted thegoof in my letter, December 1976 BYTE,about the 6800. TAB and TBA do allowexchange between the two accumulators,and it is the X register that only com-municates with A and B via memory. Asthe owner of a 6800 system, perhapsyou should have spotted this! /Maybe,but I can give the ultimate cop-out andsay facetiously that it was your letter,after all. But the point is valid of course- and I do use TBA and TAB whenevernecessary on my 6800 . . CH/

H T Gordon

641 Paloma Av

Oakland CA 94610

PS: My disparaging comments on theIM6100 were based entirely on chapter12 of volume 2 of the Osborne Asso-ciates book. Until then 1 knew nothingof the inner operation of the PDP-8except that (through a FORTRAN com-piler) it works fine. That this primitivehardware should survive (entirely on itsaccumulated software) was quite ashock! The Osborne book is a treasuryof information on design. You shouldrun an article on the profound dif-ferences among micros, and betweenminis and micros, to educate yourreaders who lack the time or backgroundto plough through the Osborne book.

Old software eventually dies, butusually when the machines which use ithave been scrapped. For example, notmany people must be using theFORTRAN compiler for the SP/RAS-65computer I saw auctioned in Cambridge

MA in 1973 (or was it 1974?) for $85(not bad for an 8 K 24 bit minicomputerprocessor in working condition,optimized with floating point for num-ber crunching). As a second example,there are still very real programs still inoperation on machines which could add,subtract, multiply, print, read cards, etc.I refer to all those old monster IBMtabulating equipments such as the 407,etc, which use plugboard programmingto create algorithms of a simple order.Why throw out a working machine if itdoesn't cost an amount approachinginfinity to maintain it?

MEETING THE ECONOMICSOF STUDENTS

My main purpose in writing thisletter is to voice a student's point ofview. I feel that my view is represen-tative of a number of college and highschool students involved in computingacross the country. Basically, I am of theopinion that we have been passed overby the industry. First of all, one mustrealize the limited budgets available tostudents. There are many powerful sys-tems in existence but these are often tooexpensive for a student of meagerearnings to afford. No matter how youslice it, a function software developmentsystem (processor 4 K bytes program-mable memory minimum, PROM moni-tor, video display, cassette 10 and pack-aging) costs well over $700, a conserva-tive approximation. Students like myselfdon't have the money. Now I'm notsaying that someone should offer asystem like the one above for $200,since that would be ridiculous; my realcomplaint is that I have not seen a lowcost alternative system which is designedwith the following idea in mind: Moststudents have access to a dial up time-sharing system, and could thus use aterminal of sorts that can be kept at

home or in the dorm. So why not designthe terminal with a processor in it, sothat we can expand the terminal into acomplete system a little bit at a time,while still using the thing as a terminalfor the timesharing service? Basically, itwould be like a Processor TechnologySOL, but without the extra memory,cassette interface and the attractive butprobably expensive case. If it were pos-sible to make such a minimal terminal ata price around the $350 to $450 range,while retaining the ability to expandupwards, I think there would be a largemarket among students such as myself.There are great numbers of studentsthroughout the nation who are capableof writing some excellent software forsmall systems, but have not even tried toget into this type of computing becauseof the cost involved.

Tony Aiuto19 Old Field LnGreat Neck NY

For the person with a tight budget,the single board computers and com-puter kits such as KIM-i, JOLT, the newMotorola 6800 evaluation kit, or theIntersil Intercept jr (to name just a few)provide the least expensive starting point(minus timesharing options). All are ex-pandable upwards but come sans videodisplay, modem or keyboard. Or, if afinished high level language system iswhat you want, go to a department storeand evaluate a programmable calculator.Alas, no video display in calculators, buttoward the end of this year we canexpect to see some interesting portablecomputing products which are variantsof calculators scaled upwards (perhapswith video outputs) at prices in thecalculator range which you can afford.

And then, of course, if you're astudent at a college, there is the old triedand true method of locating a professor,selling him or her on the idea of getting

MULTIPLE DATA RATE INTERFACING FOR YOUR CASSETTE AND RS-232 TERMINAL

the CI-812

The Only S-100 Interface H

You May Ever Need

On one card, you get dependable "KC-standard"/biphase encoded cassette inter-facing at 30, 60, 1 20, or 240 bytes persecond, and full-duplex RS-232 data ex-change at 300- to 9600-baud. Kit, includ-ing instruction manual, only $89.95*.

* Assembled and tested,$119.95. Add 5% forshipping. Texas resi-dents add 5% sales tax. PerCom 'peripherals for personal computing'BAC/MC available.

PERCOM DATA COMPANY, INC.

4021 WINDSOR • GARLAND. TEXAS 75042

12

Complete Control.

Introducing IMSAI8048 Single Board Control Computer.

Complete Control System

Intel developed the world's first singlechip microcomputer. IMSAI has built thesystem to put it to work. Instantly!

Presenting the IMSAI Single BoardControl Computer. A complete program-mable computer and hardware controlsystem on an 8'';" x 10" board.

Just plug in the power source (a 5Vpower supply or a 6V battery will do), andyou can be controlling your homeenvironment today!

The Chip Designed for Control

Intel designed the 8048/8748 single chipmicrocomputer with one thought in mind.Complete control. Everything you need isthere: CPU. RAM. IK ROM/EROM. I/O.timer/counter, interrupts . . . the works.

The Board That Implements It Instantly

There's a 24 pad hexadecimal keyboardand 9-digit LED hex display already onboard. So you can start controlling thecoffeepot and the sprinklers the minute youget the IMSAI home. Without addinganything but the connecting wires.

You can run almost any peripheralavailable. Not to mention the kids' electrictrain. The IMSAI Control Computer is

RS232 compatible. There are 12 quasi-bidirectional I/O lines with handshaking,and 14 more regular I/O lines, 5 heavy dutyrelays, and Teletype and audio cassetteinterfaces. All on one board.

There's already an extra IK of RAM onboard, plus sockets for another IK ofRAM and 2K of ROM/EROM. Still needmore memory? The IMSAI 8048 allowsexpansion up to 64K of RAM off board.

Ultimately, the only limit to this systemis your imagination.

Now, that's control.

For instant control, use the coupon provided.

GENTLEMEN:

I warn insiam control!

□ Send ROM Computer Kit S249*

□ Send EROM Computer KiiS399

□ Send assembled ROM Computer S299*^ Send assembled EROM Computer S499

□ Send 5V power supply S99*June delivery.

Cheek/MO enclosed. Ami. S

Charge my: fj BAC fj M/C

. Exp. Dale

[J Send more information.Name

Address_Cily

State/Zip

m

IMSAI Manufacturing Corporation14860 Wicks Blvd.San Leandro, CA 94577(415) 483-2093TWX 910-366-7287

you and your school into personal com-puting studies, and having the schoolmake the investment for you. This ap-proach has been done by undergraduateand graduate students with minicom-puters (and lately, microcomputers) foryears.

COVER KUDOS

It is truly refreshing to be remindedthat art in America is not confined tomuseums. The choice of cover art for theJanuary 1977 BYTE is a credit to youreditorial staff. My highest praise goes outto Mr Tinney for his insight and wellpresented message. There is one smallproblem, however: All those people likeme who removed the cover for framingare left with no protection for the firstpages of the magazine.

Stuart Beatty

1424 34th St NW

Canton OH 44709

Magazines have often inspired excel-

Are You Interested in LimitedEdition Reprints of BYTE Covers?

We have received a significantnumber of requests for reprints ofBYTE covers in full size poster form.However, the number is not sufficientto cover preparation and handling (aswell as a bit of extra remuneration tothe artists) at typical poster prices inthe $2 to $5 range.

As a way of satisfying the de-mand for covers, we would like to seeif there is reader interest in limitededition printings of covers (withoutthe BYTE logo or lettering which isapplied in the reduced magazine formof the paintings). A limited edition isdefined as a run of n < 100 prints,approved by the artist, signed andnumbered by the artist, and accom-panied by a notarized affidavitcertifying the limited quantity andposition in the run. Such sales wouldbe conducted as an auction, with thelowest numbers going to the highestbidders, ranked by the price bid. Aminimum acceptable bid would beannounced when the auction sale isannounced.

If you are interested in bidding onsuch prints, let us know by sending apostcard listing the covers you'd liketo see reprinted (by month and year),and the price range in which youwould intend to bid in such an auc-tion. Address the card to:

Cover Print SurveyBYTE Publications70 Main StPeterborough NH 03458

If we get enough response to war-rant such reprints, we'll announceselections in a future issue and solicitbids. ■

lent artwork, a practice which we atBYTE want to encourage. A classicexample is the work that artist Max fieldParrish performed early in his careerillustrating magazine covers and storiesearly in this century. For those unfa-miliar with the man, Maxfield Parrishhad a unique and aesthetically pleasingstyle of painting which will probablyclass him among the great romanticartists of all time. When I first askedRobert Tinney to execute covers forB YTE (which were constrained to thecartoon format of early BYTES by ourproduction means, not Robert's choice),I used Maxfield Parrish as represented ina book by Coy Ludwig as one of themental models to be considered. TheJanuary cover was Robert's idea andcame out quite well.

COVER REPRINT INTEREST

Please let me know whether the frontcover of February 1977 BYTE, or forthat matter, any other of the computerart you publish, is going to be madeavailable in poster-like form.

Richard H Delp

19703 Gary Av

Sunnyvale CA 94086

We have available presently one coverreprint poster: the July 1976 painting byRobert Tinney in its original form,which costs $2.95 postpaid. Order itthrough BITS (see advertisements inthis issue).

FOR YOUR CANADIAN READERS'INFORMATION

Our store, The Computer Place,officially opened November 15 1976.Before that date, during renovations,we were selling micros and peripheralson an appointment basis only. Wedeliver from stock and we do not sellwhat we can't back up.

Our store in Toronto is the largestin Canada; it includes a service andrepair facility of 1400 square feet,salesroom of 900 square feet, generaloffices of 600 square feet, and storagefacilities of 1 000 square feet.

We maintain a minimum of twosystems up for customers to work with.Additionally, we have two bench markdual floppy systems up and running:one a Processor Technology Hellios IIbased system, the other an iCOM withIBM formatting.

Our product lines include TDL,IMSAI, Processor Technology, EMAIndustries, North Star, Cromemco,iCOM, Volker Craig and Cybernexterminals, Centronics printers, Sanyomonitors, and OAE paper tape readers.We are also handling used equipment.

We are the exclusive Canadian distrib-utors for National Multiplex, SealsElectronics, and Scientific Research (the

Continued on page 10514

BUY YOURCOMPUCOLOR8001FROM THESEDEALERS.

ARIZONA

Phoenix:

Phoenix Byte Shop West12654 N. 281 h Dr.

(602)942-7300

Tempe:

lempe Byte Shop East813N.Scot(sdaleRd.

(602)894-1129

Tucson:

Byte Shop of Tucson2612 E.Broadway

(602)327-4579

CALIFORNIA

Lawndalc:

Byte Shop of Lawndale16508 Hawthorne Blvd.

(213)371-2421

Orange:

Computer Mart of Los Angeles625 W. Katella. No. 10

(714)633-1222

San Diego:

'Hie Computer Center8205 Ronson Rd.

(714)292-5302

San Francisco:

The Comptiter Store1093 Mission St.

(415)431-0640

San Jose:

Amco Electronics414 S. Bascom Ave.

(408) 998-2828

San Jose:

Byte Shop

155 Blossom Hill Rd.

(408) 226-8383

Van Nuys:

Computer Components5848 Sepulveda Blvd.

(213)786-7411

CONNECTICUT

Windsor Locks:

The Comptiter Store63 S. Main St.

(203)627-0188

FLORIDA

Coral Gables:

Sunny Computer Stores1238A S.Dixie Hwy.

(305)661-6042

Tampa:

Microcomputer Systems144 S. Dale Mabry Hwy.

(813)879-4301

GEORGIA

Atlanta:

Atlanta Computer Mart5091-BBuFordHwy.

(404)455-0647

HAWAII

Honolulu:

Compact ComputersP.O. Box 1(X)96

(808)373-2751

ILLINOIS

Champaign:

The Numbers Racket518 E.Green St.

(217)352-5435

Evanston:

Illy Billy Machine1316 Chicago Ave.

(312)328-6800

Park Ridge:

Chicago Computer Store157'lhlcoll Rd., Hwy. 62

(312)823-2388

INDIANA

Indianapolis:

Home Computer Shop10447 Chris Dr.

(317)894-3319

MARYLAND

Rockvillc:

Computer Workshop. Inc.5709 Frederick Ave.

(301)468-0455

MASSACHUSETTS

Burlington:

The Compulcr Store120 Cambridge St.

(617)272-8770

MICHIGAN

Iroy:

General Computer Company2017 Livemois

(313)362-0022

MINNESOTA

Minneapolis:

Cost Reduction Services3142 Hennepin Ave. So.

(612)822-2119

MISSOURI

Kansas City:

Computer Workshop of Kansas Citv6903 Blair Rd.

(816)741-5055

NEW JERSEY

Iselin:

The Computer Mart501 Route 27

(201)283-0600

NEW YORK

East Meadow:

The Comptiter Marl of Long Island2070 Front St.

(516)794-0510

New York:

[fie Compulcr Mart314 5th Ave.

(212)279-1048

OHIO

Columbus:

Compulervision894 W. Broad St.

(614)228-2477

SOUTH CAROLINA

Columbia:

Bvte Shop2018 Greene Si.

(803)771-7824

TEXAS

Houston:

Communications Center7231 Fondren

(713)774-9526

Richardson:

The Micro Store

634 S. Central Expressway

(214)231-1096

WASHINGTON

Seattle:

Retail Compulcr Store410 NE 72nd St.

(206)524-4101

WISCONSIN

Beloit:

Austin Computers1835 Northgale

(608) 365-6096

Watertown:

General lYecision Fled ionics207 Rhine Si.

(414)261-8148

Comi

ration

NOW $2750.AMERICA'S LOWEST-PRICEDPERSONAL COMPUTER SYSTEMWITH COLOR VECTOR GRAPHICS.

By taking advantage of thenew technologies available tothe industry today, we've con-sistently been able to give youone of the best prices on themarket. Now because of greatresponse, we can give you thebest price. You can now buythe Compucolor 8001 for thereduced price of $2750. A com-plete stand-alone system withexpanded graphics softwarefor plotting points, vectors andbargraphs on a 160 x 192addressable grid —in color.Eight independent backgroundand foreground colors.

The Compucolor 8001 hasan Intel 8080 CPU, 341/0ports and a color display withan effective band width of 75MHZ compared to 5 MHZ forstandard TV sets. In fact theCompucolor is the only totallyintegrated system on the mar-ket which includes a colordisplay. You can also have spe-cial options for the Compucolor8001 right now, including: MiniDisk Drives for extra memory,light pens and a variety ofspecial keyboard features.BASIC 8001 Is Easy To Learn.Compucolor's BASIC 8001 is

a conversational programminglanguage which uses English-type statements and familiarmathematical notations. It'ssimple to learn and easy to use,too. Especially when it comesto intricate manipulations orexpressing problems moreefficiently. The BASIC 8001Interpreter runs in ROM mem-ory and includes 26 statementtypes, 18 mathematical func-tions, 9 string functions and 7command types for executing,loading, saving, erasing, con-tinuing, clearing or listing theprogram currently in core.Expandable Memory To 64K.The Compucolor 8001 has UKbytes of non-destructible read-only memory which handlesthe CPU and CRT operatingsystems as well as BASIC8001. Sockets are in place foran additional 2IK of EPROM/MROM memory. The RandomAccess Main Memory has 8Kbytes for screen refresh andscratch pad, 8K bytes for userworkspace and room for 16Kbytes of additional user work-space. The Compucolor alsocomes complete with a conve-nient mass storage device,

Floppy Tape Memory. It's an8-track continuous loop tapesystem, with a Baud rate of4800 and an extra storagecapacity of up to 1024K bytesper tape.

Color Graphics At

Alphanumeric Black AndWhite Prices.That's what we're becomingfamous for, and thanks to thetremendous response to theCompucolor 8001, we've beenable to reduce our price evenlower —to $2750. Look overour dealer listing on the adja-cent page for the dealer nearestyou.Then drop by for a dem-onstration. And while you'rechecking out the Compucolor8001, check out your dealer'sfinancing plan. He can help youturn a good deal into a gooddeal more.

Compucolor Corporation,P.O. Box 569, Norcross,Georgia 30091.

Compucolor Corporation

(S5&

The Small Computer

Twenty-five years ago a computer as powerful as thenew Processor Technology Sol-20 priced out at a cool million.

Now for only $995 in kit form or $1495 fullyassembled and tested you can have your own small computerwith perhaps even more power. It comes in a package about thesize of a typewriter. And there's nothing like it on the markettoday. Not from IBM, Burroughs, DEC, HP or anybody else!

It fills a new role

If you're an engineer, scientist or businessman, theSol-20 can help you solve many or all of your design problems,help you quantify research, and handle the books too. For notmuch more than the price of a good calculator, you can have highlevel computer power.

Use it in the office, lab, plant or home

Sol-20 is a smart terminal for distributed processing.Sol-20 is a stand alone computer for data collection, handlingand analysis. Sol-20 is a text editor. In fact, Sol-20 is the keyelement of a full fledged computer system including hardware,software and peripheral gear. It's a computer system with akeyboard, extra memory, I/O interfaces, factory backup, servicenotes, users group.

It's a computer you can take home after hours to playor create sophisticated games, do your personal books and taxes,and a whole host of other tasks.

Those of you who are familiar with small computerswill recognize what an advance the Sol-20 is.

Sol-20 offers all these features as standard:

8080 microprocessor—1024 character video displaycircuitry — control PROM memory —1024 words of static low-power RAM —1024 words of preprogrammed PROM—built-incassette interface capable of controlling two recorders at 1200bits per second — both parallel and serial standardized interfaceconnectors — a complete power supply including ultra quietfan — a beautiful case with solid walnut sides — software whichincludes a preprogrammed PROM personality module and a datacassette with BASIC-5 language plus two sophisticated computervideo games — the ability to work with all S-100 bus products.

Full expansion capability

Tailor the Sol-20 system to your applications with ourcomplete line of peripheral products. These include the videomonitor, audio cassette and digital tape systems, dual floppydisc system, expansion memories, and interfaces.

Write for our new 22 page catalog.

Get all the details.

Processor Technology, Box B, 6200 Hollis St.,Emeryville, CA 94608. (415) 652-8080.

Ifiife^^gy

A Catalogof Liberating Home Computer Concepts

Ted M Lau1219 Pioneer DrSt Louis MO 63132

Unlike commercially developed systems, home growncomputer systems are not required to justify themselvesdirectly in terms of dollars and cents, which means thathome grown systems can be put to a wide variety of uses,from whimsical games for pure enjoyment to public servicesfor helping people, uses that are certainly worthwhile butwhose worth cannot be quantified. I suspect the computerhobby will continue to address itself to a broader range ofapplications even after prepackaged consumer orientedsystems have filled the marketplace in the next few years.

But like all powerful technologies, home computersshould not be allowed to wander into any applications forwhich they seem suited, but should be guided by humanvalues. Technology is often called "value free," meaning itis neither good nor bad of itself, but by virtue of the effectsof its applications. To be "good," humankind (representedby each individual) must first define its will, and only thenhow technology can serve it.

Presented here is a catalog of home computer applica-tions that serve the goal of "human liberation" as Ipersonally envision it. Many of the applications listed canbe found in other sources, but many well known applica-tions are omitted. I have attempted only to include enoughexamples to illustrate the concepts underpinning eachcategory so that the reader will be able to use the catalog togenerate new applications of his or her own. Along the wayI briefly introduce some thoughts of Marshall McLuhan, themedia guru, but interested readers should consult a libraryfor a fuller treatment.

In brief my message is: Home computers should serveyour values. If you don't value war games, don't put themon your computer. I value "human liberation" and here'show I see home computers aiding that endeavor. Butwhether you agree with my vision or not is incidental. Usethis catalog as an example. Go to it: Define your ownvalues, and then define how the computer might help.

A. LEISURE TIME LIBERATION1. Games

a. The computer as game board or game recorder:The game participants input their moves, the

computer updates the game status display(s), andkeeps move records.

1) Go, Stratego, Risk, Avalon-Hill games (ingeneral, games with complex boards): Using agraphics display device to represent board andtoken position, and a keyboard or panel forinput of moves.

2) Speed chess: Using a wired chessboard as aninput device, the computer senses each player'smove, keeps the clocks, and prints a list ofmoves at completion of the game. A movenumber display allows the players to addadditional time periods if both players satisfythe first period requirements (rather thanhaving the game end when one player's timeexpires. This is a variation that stresses speedybut not quality play).

b. The computer as kibitzer: One participant inputsall moves, and is aided in playing by advice fromthe computer.

1) Chess: The computer advises of threats orpotential threats against your pieces, eg: forks,skewers, checks, discoveries. Let two players,each with computerized kibitzer, compete witheach other for accuracy, time, etc.

2) Blackjack (and games of chance): The com-puter advises whether to stay or hit, and howmuch to bet. Many statistically based blackjacksystems exist, some in print, waiting to bealgorithmatized.' (Imagine the impact on LasVegas of hordes of gambling crazed peopleequipped with wristwatch-sized kibitzers of thisvariety. Or imagine the sales potential of such aone chip blackjack calculator!)

c. The computer as opponent: The player inputs amove, and the computer responds with its own.An example is HEX PAWN by Robert Wier [page36, November 1975 BYTE], where the computerlearns to play better through experience.

How about dominoes, backgammon, go-moku(five in a row), hex, football, checkers? The

17

computer could be made into an extremely skillfulplayer in these games, and a difficult opponent tobeat. Games that are not soluble are best.

Or get your computers together for a computertournament, with no human players at all. TheFirst Annual World Computer Chess Tournamentwas held during the summer of 1975.

2. Simulations

a. The computer as an analog: The player inputsinitial parameters, and optionally changes theparameters during the simulation. The computeroutputs the values of variables that are describedby a logical or mathematical model.

Familiar examples are LIFE (cell colonygrowth), LEM (lunar landing), and ROADRACE.

1) Patient work-up: The computer simulates aperson with an illness by responding to ques-tions posed by a medical student. The studenttries to deduce the illness (make a diagnosis) byrecognizing a pattern of symptoms.

2) Environment: Human and animal populationdynamics, pollutant flow up the food chain,nuclear reactor dynamics, automobile fueleconomy — all can be simulated. (Simulationshackers beware, though: are you creating anaccurate model or did you overlooksomething?^)

3. Toys

a. The computer as plaything: The infant inputsactions, and the computer responds playfully.

1) Crib entertainer: The baby strikes crib objects(sensors), and the computer outputs funnynoises, blinks lights, motivates other objects,etc.

b. The computer as robot: The computer motivatesitself around an environment, and optionallyperforms work.

Examples are the maze-running mechanical ratwhich learns, the object-avoiding turtle, the house-maid robot, the barmaid robot, and the billiardplayer.

1) Piano player (not to be confused with playerpiano): Robot sits on the bench, reads thenotes, and plays the piano. (Or why make ithumanoid at all? Simply mount controls toeach key.)Using the computer for fun avoids consuming ready-made leisure time activities. As opposed to TV ping pong,home computers are general purpose and do not comeequipped with software ready for action. Computer playersmust first decide how to spend their leisure, and then mustcreate the means for playing, or purchase software for thepurpose. As much or more enjoyment, experience andlearning occurs during the creating as during the playing.

B. MEDIA LIBERATION1. Translation

a. The computer as Seeing Eye dog: Inputs from theenvironment are translated by the computer intooutputs in a different sensory mode. These out-puts serve as substitute inputs for the user.1) Printed text to spoken word for the blind: A

very sophisticated minicomputer based productwas recently announced for this purpose. Vocalanalysis, computer-generated vocalization, andtext recognition are reasonable goals for ad-vanced home computer technicians. Othertranslations for the blind include spatial per-ception to sound and spatial perception tovibration.

2) Touch, shorthand, or sign to speech for themute,b. The computer as linguistic translator: Inputs in

one language are translated and output in another

language.

1) Cross assemblers: Assuming the computerhobby remains linguistically diversified, transla-tors will be valuable tools for the promoting offree software exchange of programs in thepublic domain.

2) Human language translation: Most experts havebeen disappointed with results of computerizedtranslators, except when the context is specific,as in technical journals. Their experience doesnot eliminate the possible benefits of limitedcapacity English to Spanish translation ma-chines in government offices and elementaryschools in many parts of the US.

2. Interpretation

a. The computer as mass media bodyguard: Semanticinputs to the computer are interpreted and outputas information whose meanings differ from thoseof the inputs.

1) Political "doublespeak" interpreter:-' Takeswritten or spoken text and turns buzzwordsinto their suppressed, connotative, or impliedmeanings. Easy computer program, but whodefines the dictionary of doublespeak terms?

2) TV commercial replacer: The computer senseswhen a commercial message comes on the airand substitutes a viewer-chosen display such asa game, art graphics, trivia quiz, silence, etc.

3) Remote lie detector: The computer measuresthe stress evidenced in the vocal, facial, andmanneristic expressions of the person deliveringa TV speech, and outputs its findings to theviewer/''

3. Condensation

a. The computer as library card catalog: The com-puter stores an index to media events.

1) Phonograph recording, cassette, magazineindex: by subject, author, keyword. Computercould scan year-end index to magazine articlesfor input. Books and records could have coversscanned.

2) Public library book search network: User inputssearch argument and receives list of matchingtitles.

b. The computer as media monitor: The computerscans many media channels and stores either entireor condensed media events whose contents matchthe interests input by the user. The user thenretrieves the stored events.

1) Entire verbal events: The computer stores all

18

Print \bur Heart Out.

With help from the Digital Group, naturally.

Now, that small computer system you own or have beenconsidering for personal or business use suddenly be-comes a lot more usable—with the addition of a full-sizeimpact printer from the Digital Group. A printer designedfor small computers that need big output (like yours).

With the Digital Group printer, you can print your heartout...and it won't cost an arm and a leg. The DigitalGroup printer is available for less than $500. That'sright—$500.

Just look at these specifications:

• Fast—120 characters per second

• 96 characters per line

• 12 characters per inch horizontal

• 6 lines per inch

• Makes up to 4 copies simultaneously

• Character set and pitch variable under softwarecontrol—double width characters, etc.

• 5 x 7 character matrix

• Ribbon has built-in re-inkers for a life of10,000,000 characters

• Paper can be either a standard 8V2-inch roll, fanfoldor cut page

• Interfaces to 8-bit parallel ports

There are lots of capabilities and outstanding features of theDigital Group printer... and (as always) the best news isour price. Kit prices start as low as $495 for the printer andinterface card. It simply can't be beat.

Find out all the facts about the Digital Group printer now.Just fill in the coupon below or give us a call for the details.We think you'll find a place for our printer in your system...and in your heart.

jBM](po^

J

P.O. Box 6528

Denver, Colorado 80206

(303) 777-7133

Quick. I want to print my heart out.

Send me all the details on your full-size impact printer.

Name.

Address .

City/State/Zip_

Please print.

CENTER-MARGIN

PRE-

ELECTRIC

MEDIA

POINT-TO-POINT

ELECTRICMEDIA

Figure I: Communications Structures. McLuhan identifies two major classes of communications structures: center-margin, andpoint to point. The center margin structure at left is typical of pre-electric forms of media such as newspapers or books, in whichinformation flaws from the center to the periphery of the network. A point to point structure, as at right, typifies the manyelectronic forms of media such as the telephone network, ham radio, CB radio, etc. Due to political and economic factors, thecommunications structure of some of the electronic media such as commercial radio and television more resembles thecenter-margin case. But with more and more home computers, with sophisticated network terminal capabilities, the typicalhome communications mode will shift increasingly towards the point to point case.

TV broadcasts from all channels on video tapes,then reviews each segment for keywords, andspools off only those in which a certain level ofkeyword density occurs. Similar processing forAP Teletype wire, police, shortwave, and hambands, etc.

2) Summarized verbal events: The computer moni-tors all radio or TV newscasts and prints asummary of nonredundant news items.

3) Music monitor: The computer monitors allstereo (or quad) FM broadcasts, identifiessingers and groups by comparing to stored vocalprofiles, and tapes tracks of desired artists if theevent does not already exist in the library! (Achallenging application perhaps, but a good wayto build a personal music collection!)

4. Alternate Media

a. The computer' as a public bulletin board: Thecomputer stores messages from individuals toother individuals or to the public. Users input,search for, browse through, and retrieve storedmessages at remote, publicly accessible terminals.

1) Carpool data base: Riders wanted, rides neededby destination and departure time are matchedvia a public computer network.

2) People skill resources data base: People offeringskills and services match with those needingtraining, services, etc. A public access computernetwork was set up in Berkeley and was usedfor the above two, and many other, purposes.The network needs a scheme for categorizing

the messages and message searches, as with

classified ads in newspapers.3) Interactive computerized "singles club" and

dating service,b. The computer as encoder or decoder: The com-puter encodes or decodes alphanumeric messagesfor transmission or reception over communicationschannel.

1) Telemetry bands: Computer-receiver com-bination detects and decodes scientific data inbroadcasts from satellites and space probes.

2) Amateur broadcast bands: The computer inter-faces between operator and transmitter andreceiver for Morse CW encoding and decodingto alphanumeric, or enciphering and deci-phering of private secrecy codes.

Using the computer as an interface to the mass mediaopens the possibility of liberating the individual frominformation overload caused by multichannel disseminationof largely redundant data. For example, almost all newsstories on TV, radio, and in newspapers (excluding localstories) come from the two wire services, ie: are the samebasic set of stories endlessly replicated. Increasing informa-tion processing power at the receiver will allow sampling ofmore diversified sources of news (or use of the gained freetime in other ways).

Diversification also implies decentralization, sincespeedier information throughput (such as the personalizedcomputer allows by enhancing both the broadcast andreception of data) on more numerous channels (say, cableTV or radio bands) will help transform our center margin

20

See Sol Systems at your dealer

ARIZONA

Byte Shop Tempe813 N. Scottsdale Rd.Tempe. AZ 85281

Byte Shop Phoenix12654 N. 28th Dr.Phoenix, AZ 85029

Byte Shop Tucson2612 E. BroadwayTucson. AZ 85716

CALIFORNIA

Bits "N Bytes

679 S. State College Blvd.

Fullerton, CA 92631

The Byte Shop1514 University Ave.Berkeley. CA 94703

The Byte Shop2626 Union Ave.Campbell, CA 95124

Byte Shop Computer Store6041 Greenback LaneCitrus Heights, CA 95610

Computer Center1913 Harbor Blvd.Costa Mesa, CA 92627

The Byte Shop

16508 Hawthorne Blvd.

Lawndale, CA 90260

The Byte Shop1063 El Camino RealMountain View. CA 94040

The Computer Mart624WestKatella#10Orange, CA 92667

The Byte Shop2227 El Camino RealPalo Alto, CA 94306

Byte Shop

496 South Lake Ave.

Pasadena, CA 91101

The Computer Storeof San Francisco1093 Mission StreetSan Francisco, CA 94103

Byte Shop

321 Pacific Ave.

San Francisco, CA 94111

The Computer Room124H Blossom Hill Rd.San Jose, CA 95123

The Byte Shop509 Francisco Blvd.San Rafael, CA 94901

The Byte Shop3400 El Camino RealSanta Clara, CA 95051

The Byte Shop2989 North Main St.Walnut Creek, CA 94596

Byte Shop

14300 Beach Blvd.

Westminster, CA 92683

RecreationalComputer Centers1324 South Mary Ave.Sunnyvale, CA 94087

COLORADO

Byte Shop2040 30th St.Boulder, CO 80301

FLORIDA

Byte Shop of Miami7825 Bird RoadMiami, FL 33155

MicrocomputerSystems Inc.

144 So. Dale Mabry Hwy.Tampa, FL 33609

Sunny Computer StoresUniversity Shopping Center1238A S.Dixie Hwy.Coral Gables, FL 33146

GEORGIA

Atlanta Computer Mart5091-B Buford Hwy.Atlanta, GA 30340

ILLINOIS

The Numbers Racket518 East Green St.Champaign, IL 61820

ilty bitty machine co.1316 Chicago Ave.Evanston, IL 60201

itty bitty machine co.42 West RooseveltLombard. IL 60148

INDIANA

The Data Domain406 So. College Ave.Bloomington, IN 47401

The Data Domain219 West ColumbiaWest Lafayette, IN 47905

The Data Domain7027 N. Michigan Rd.Indianapolis, IN 46268

KENTUCKY

The Data Domain3028 Hunsinger LaneLouisville, KY 40220

MICHIGAN

The Computer Storeof Ann Arbor310 East WashingtonAnn Arbor, MI 48104

General Computer Store2011 LivernoisTroy, MI 48084

Computer Mart of Royal Oak1800 W. 14 Mile Rd.Royal Oak, MI 48073

NEW JERSEY

The Computer Martof New Jersey501 Route 27Iselin, NJ 08830

Hoboken Computer WorksNo. 20 Hudson PlaceHoboken, NJ 07030

NEW YORK

Audio Design Electronics487 Broadway, Ste. 512New York, NY 10013

The Computer Corner200 Hamilton Ave.White Plains, NY 10601

The Computer Mart

of Long Island

2072 Front Street

East Meadow, L.I. NY 11554

The Computer Martof New York314 Fifth Ave.New York, NY 10001

Synchro Sound Enterprises193-25 Jamaica Ave.Hollis, NY 11423

OREGON

The Real Oregon

Computer Co.

205 West 10th Ave.

Eugene, OR 97401

Byte Shop Computer Store

2033 S.W 4th Ave.

Portland, OR 97201

Byte Shop Computer Store3482 S.W. Cedar Hills Blvd.Beaverton, OR 97005

OKLAHOMA

High Technology

1020 West Wilshire Blvd.

Oklahoma City, OK 73116

RHODE ISLANDComputer Power, Inc.M24 Airport Mall1800 Post Rd.Warwick, RI 02886

SOUTH CAROLINAByte Shop2018 Green StreetColumbia, SC 29205

TEXAS

The Micro Store

634 So. Central Expressway

Richardson, TX 75080

Computertex

2300 Richmond Ave.

Houston, TX 77098

Interactive Computers

7646 Dashwood Rd.

Houston, TX 77036

WASHINGTON

Byte Shop Computer Store

14701 N.E. 20th Ave.

Bellevue, WA 98007

The Retail Computer Store

410 N.E. 72nd

Seattle, WA 98115

WASHINGTON. D.C. AreaMedia Reactions Inc.11303 South Shore Dr.Reston, VA 22090

WISCONSINThe MilwaukeeComputer Store6916 W. North Ave.Milwaukee, WI 53213

CANADA

The Computer Place186 Queen St. WestToronto, Ontario M5V 1Z1Trinlronics160 Elgin St.Place Bell CanadaOttawa, Ontario K2P 2C4First CanadianComputer Store Ltd.44 Eglinton Ave. WestToronto, Ontario M4R 1A1Pacific Computer Store4509-11 Rupert St.Vancouver, B.C. V5R 2J4

Processor Technology, 6200 B Hollis Street, Emeryville, CA 94608, Phone (415) 652-8080

2 b. ART OBJECT AS

ALIEN INTELLIGENCE

2a. MICROPROCESSOR-BASED ART OBJECTS

11

l

11

AFFECTORS

OR

DISPLAY

"11

1

1

MPU

( OBSERV

1 \

1

RECEPTORS

l_

Figure 2a: A system diagram of art object components andart object to observer interaction. The interaction isidentical to any computerized environment such as gaming,CAI, etc, except that the art object attempts to expose theclever operations of the computer rather than to pursuesome functional purpose.

communication structure into a point to point structure (asprophesied by McLuhan^ and represented in figure I).

C. ARTISTIC LIBERATION

Artists will be among the first to exploit the capabilitiesof low cost microprocessor-based systems. John Whitney,for example, proposes to use MPUs to help create abstractanimated TV graphics, a form he pioneered prior to thedays of inexpensive processors." Since most artists alreadyknow how they would use computers, I shall not attempt acomprehensive listing here. While I suspect that most art isliberating in some sense or other, I will restrict myself toapplications that illustrate McLuhan's idea that art is ananti-environment which exposes the usually invisible effectsof media on us (see figure 2a).

1. Self Exposure

a. The computer as an alien intelligence: Data inputsand program commands arc input to thecomputer-driven artwork through means notreadily apparent to the participant. The artworktransforms the data according to a program anddisplays. The participant attempts to deduce thetransformations and program commands by vary-ing the supposed inputs. In other words, theartwork is a black box whose inner logic theviewer attempts to deduce (see figure 2b).

1) Proximity synthesizer (theramin): The distanceof the observer's body parts from hiddensensors determines pitch, fillers, noise, ampli-tude, waveform, etc. Observer explores theobject's surface. How the sensors determine thesound depends upon a Boolean concatenationof variables, eg: hand close to sensor I ANDfoot close to sensor 2 yields white noise, etc.

2) Eavesdropper: The pattern of lights displayedchanges through time, but different types ofchanges arc initiated upon detection of vocalkeywords in the viewing room.

b. The computer as a Skinner box: The computerrewards certain behaviors of the viewer. Theviewer may deduce that he is in a Skinner box foroperant conditioning. (Sec figure 2c and theliterature of B F Skinner.')

INPUTS-VARIABLES ORPROGRAM COMMANDS

Figure 2b: The art object as an alienintelligence. In this conception, theobject interprets inputs as data andprogram commands. Data is thentransformed by the artwork and sentback out. The transformation is acomplicated (but designed) functionof past commands and data.

2c. ART OBJECT ASSKINNER BOX

I. STIMULUS3.REWARD

2. RESPONSE

Figure 2c: Another way of viewing theart object is as a stimulus-responseprogram. The complications and vari-ations involved in a big program canmake the object quite interesting in-deed.

1) Arms above head behavioral goal: Video inputsof the viewer are displayed back to the viewer.The computer analyzes the viewer's hand posi-tions: the higher the viewer raises his hands, theclearer his displayed self image becomes, until,overhead, the viewer can clearly sec his ownimage. Random movements will be rewarded atfirst, such as raising a handbag onto theshoulder or adjusting eyeglasses.

2) Touching: If viewers touch each other, artworkdispenses a souvenir (penny, slogan button,raffle ticket).

The purpose of these computer driven artworks is toreveal to a large viewing public in graphic, intriguing,enjoyable ways, the sophistication and capabilities ofcomputerized environments. Even for the public fortunateenough to interface with computers via CRT in museums,libraries, and schools, the computer remains transparentand hidden. These art objects can be designed to expose thecomputer's workings.

22

XEL3I

New books... for everyone who's intotheir own computer. Programs.Fun. Games. Languages. Excitement.

SCELBAL, the new microcomputer languagethat's simpler than machine language.

Scientific ELementary BAsic Language for "8008"/"8080"systems. A complete, illustrated program book. Routines.Techniques. Source Listings. Flow Charts. And more.Took several years to develop. Now yours for many yearsto come. First time that intimate details of higher levellanguage has been offered for such a low price. Only $49!You get 5 Commands: SCR, LIST, RUN, SAVE, LOAD.14 Statements: REM, LET, IF .. . THEN, GOTO, FOR withSTEP, END, INPUT, PRINT, NEXT, GOSUB, RETURN andoptional DIM. 7 Functions: INT, SGN, ABS, SQR, RND,CHR, TAB. And, it runs in 8K and more. Here's all thedata needed to customize a high level language for yoursystem ... at a fraction of the cost!

A complete language for"8008'7"8080" systemsincluding source listings,routines, (low charts andmore!

Order your copy today! Getstarted advancing your system!

SCELBAL SUPPLEMENTS...

SCELBAL has taken off so fast, two special supple-ments had to be printed. First, there's Extended MathFunctions: SIN, COS, LOG (BASE E), EXP (BASE E)and ATN . . . only $5.00 ppd. The second supplement,String Handling Capabilities, includes the numericfunctions LEN and ASC. It sells for only $10 ppd.

Cook up mouthwatering programsfor your "8080" or "6800"!

Delectable "how to" facts,including descriptions of"8080" or "6800" instructionsets. How to manipulatestacks. Flow charts. Sourcelistings. General pur-pose routines formultiple precisionoperation. Program-ming time delays forreal time applications.

Order your copiesStart cookin'! Bon

Random number generators.And more. You even get float-ing point arithmetic routines!Input/output processing forbasic I/O programmingthrough interrupt processing.And so much more, we can'tlist it all here. Scelbi'sSoftware Gourmet Guidesand Cookbooks for"8080"or "6800". (Specify!)

today! $Q95Appetite. «7 each ppd.

/^illAW Microcomputer Outer

\Wpllrl,#V¥ Space War Games ...

Captain your own starship on an inter-gallacticjourney to adventure. Meet alien ships in realisticcombat. Plan a painstaking journey filled withbattles, refueling problems, weaponry, warpfactors and more—all against your "8008"/"8080"or "6800" computer. Either complete book, writtenin machine language for 4K memory, is anongoing, ever-changing interstellar adventure,including source listings, flow charts, routines andmuch more. Choose your copy today. Blast offto high adventure in outer space!

Order either GALAXY today! $

14

95

each ppd.

Prices shown for North American customers.Master Charge. Postal and Bank Money Orderspreferred. Personal checks delay shippingup to 4 weeks. Pricing, specifications,availability subject to change without notice.

ICE LEI COMPUTERCONSULTING

Scelbi Books are availablein many fine Computer Stores.

Post Office Box 133 PP STNMilford, CT 06460

D. EDUCATIONAL LIBERATION

The problem educators and psychologists have identifiedas the main barrier to nationwide adoption of CAI(interactive Computer Assisted Instruction) is the high costof hardware; but with the development of inexpensiveprocessors, this barrier will be overcome. The benefits ofCAI are well documented: More pupils master the materialin less time than with conventional teaching techniques.With hardware costs decreasing, the most costly componentof CAI will be software development, so if you want to doCAI, get together early with other developers on softwarestandards so that course material can be shared. A CAIsoftware network is a must.

Educational liberation as a computer application meansevery technique in this catalog. What follows is a more orless traditional listing of CAI categories, given withoutexamples. Interested readers can pursue CAI in periodicalsbeginning with Educational Technology.

1. Drill and Practice

a. The computer as drill instructor: The computerpresents no new material (new material would betaught in a traditional way), but would test andreinforce learning through repetitious questioning,correcting wrong answers and accepting correctanswers.

2. Tutorial

a. The computer as lecturer: In "linear" fashion, thecomputer presents new material to the learner andperiodically asks questions, but the speed ordirection of presentation is not modified by thecorrectness or incorrectness of the answers.

b. The computer as absent minded professor: In this"intrinsic" or "branching" mode, the computeralters its presentation depending upon the appro-priateness of the previous answer only.

c. The computer as tutor: In "adaptive" mode, thecomputer alters its presentation based upon theprevious pattern of student responses and focusesin on weaknesses, or skips over familiar material,etc. This is the most difficult form to create.

3. Games and Simulations

4. Problem Solving

a. The computer as a computing machine: The

i student uses the computer as an aid in solving a

problem by inputting an arithmetic or algebraic

expression, or by writing a computer program

directing the computer to solve the problem.

5. Dialogue

a. The computer as Socrates: The computer presentslarge bodies of information, and optionally queriesthe student or is queried by the student. Thecomputer analyzes the student's remarks and leadsthe student to an understanding of his ownweaknesses, need for additional study, or satis-factory comprehension, etc.

6. Discovery Learning

a. The computer as a land of exploration: Thecomputer offers a structured informational en-vironment and the tools for its exploration. Thestudent directs his/her own exploratory efforts.1) Hypertext: See Ted Nelson's Computer Lib."CAI promises to break down the lock step approach to

learning wherein all learners, grouped by age instead of byaptitude or achievement, learn the same material at thesame pace. But this promise may cause problems theexperts don't foresee: CAI threatens the traditional roleand authority of teachers, threatens the institutional role ofpublic schools as keeper, babysitter and socializer ofchildren, threatens the modern routine of family lifeordered around a nine month, full time involvement byoffering children the possibility of learning at homewhenever they please. CAI still has a large mass of societalinertia to overcome.

E. COMMUNITY LIBERATION

"Community" can be any geographically localized groupof people who have interests, problems, goals, and concernsabout their lives and locality in common. One family or oneblock can be a community, or a city, but in general I amthinking of a neighborhood — with a traditional history,perhaps a distinct ethnic background, traditional localbusiness and industry, topographic boundaries, and so on.

The problem communities face in our day and age is thatthey have been gobbled up by the cities, and have lost thewherewithal to exercise control over factors and decisionsaffecting their existence, issues such as housing, transpor-tation, health care, zoning, schools, and so forth.9 Thissection proposes how inexpensive computer technologymight be used to benefit community development in termsof gaining two potent resources: economic power andpolitical power.

1. Economic Power

a. The computer as a service for sale: Many wellknown applications could be sold to customers ona per use basis, where the clients do not need fulltime dedicated systems of their own.

1) Mailing list address labels.

2) Small business accounting and billing.

Once a local business or agency is paying forits computer with these services, it couldperform additional services on a free or nominalfee basis of the sort listed in previous sections.

3) Social service and health care referral andfollowup system.

4) Part time job match service.

b. The computer as hardware for sale: The neighbor-hood computer store has already arrived, withyour friendly local retailer selling microprocessorhardware and related services.

1) PROM programming services.

2) Hardware maintenance service.

3) Low cost peripheral manufacture.

c. The computer as software for sale: People who areunable to travel or do heavy work (as mainte-nance, service, or manufacturing operations mightrequire) could develop software, for which therewill be increasing demand. System software likemonitors, compilers, access methods, and sort-merge utilities; common subroutines like mathe-matical functions; and application packages couldbe developed and sold. Some corporate names I'dlike to see:

Continued on page 162

24

435/278

MICRO-PROCESSORAPPLICATIONSMANUAL

by Motorola,Inc.

Pub. price,Club price,

$28.50$22.50

&M

769/29X

THE

INFORMATIONSYSTEMSHANDBOOK

by F. W.McFarlan andR. L. Nolan

Pub. price, $30.00Club price, $22.50

769/338ASSEMBLERLANGUAGE WITHASSIST

by R. Overbeekand W.Sirgletary

Pub. price, $14.95Club price, $11.95

770/271

BUCHSBAUM'S

COMPLETE

HANDBOOK OF

PRACTICAL

ELECTRONIC

REFERENCE

DATA

by W. H.

Buchsbaum

Pub. price, $17.95Club price, $13.50

191/59X

BASICS OF DATACOMMUNI-CATIONS

Edited by H. R.Karp

Pub. price, $19.50Club price, $15.95

768/641

MINICOMPUTERSYSTEMS

Organizationand Programming(PDP-11)by R. H.Eckhouse

Pub. price, $15.95Club price, $12.50

introductory oilerto now members of the

COMPUTER PROFESSIONALS'BOOK CLUB

any one

of these greatprofessional books

forjjjonly

values upto $30.00

Special $1.89 bonus book comes to youwith your first club selection

Be sure to consider these books as well—

[vMkTEB

767/246

A COMPUTERPERSPECTIVE

by C. Eamesand R. Eames

Pub. price, $15.00Club price, $12.75

768/943

FORTRAN IVPROGRAMMING

by V. T. DockPub. price, $8.95Club price, $7.60

394/555

OPERATINGSYSTEMS

by S. E.

Madnick andJ. J. Donovan

Pub. price, $19.50Club price, $14.25

399/107INTRODUCTIONTO

MATHEMATICALTHEORY OFCOMPUTATIONby Z. MannaPub. price, $22.00Club price, $16.50

768/455

ASSEMBLY LEVELPROGRAMMINGFOR SMALLCOMPUTERS

by W. WellerPub. price, $14,95Club price, $12.50

768/498

DIGITAL SYSTEM

DESIGN

AUTOMATION

Languages,Simulation andData Base

by M. A. BreuerPub. price, $18.95Club price, $15.95

768/749

MICRO-PROCESSOR/MICRO-PROGRAMMINGHANDBOOKby B. WardPub. price, $9.95Club price, $8.45

769/32X

YOUR COMPUTERAND THE LAW

by R. Bigelowand S. Nycum

Pub. price, $18.95Club price, $15.75

768/773THE DESIGNOF AN

OPTIMIZINGCOMPILER

by W. Wulf,R. K. Johnson,C. B. Weinstock,S. O. Hobbsand C. M.Geschke

Pub. price, $13.50Club price, $10.95

768/528

DATA

PROCESSING

SYSTEMS

ANALYSIS AND

DESIGN

by R. J. Condon

Pub. price, $13.50

Club price, $10.75

save time and money

by joining McGraw-Hill's new

COMPUTER PROFESSIONALS'BOOKCLUB

SI

THIS new professional club is designed to meet your day-to-day on-the-jobneeds by providing practical books in your field on a regular basis at belowpublisher prices. If you're missing out on important technical literature—iftoday's high cost of reading curbs the growth of your library—here's the solutionto your problem.

The Computer Professionals' Book Club was organized for you, to provide aneconomical reading program that cannot fail to be of value. Administered bythe McGraw-Hill Book Company, all books are chosen by qualified editors andconsultants. Their understanding of the standards and values of the literature inyour field guarantees the appropriateness of the selections.

How the Club operates: Every month you receive free of charge The ComputerProfessionals' Book Club Bulletin. This announces and describes the Club'sfeatured book of the month as well as alternate selections available at specialmembers' prices. If you want to examine the Club's feature of the month, you donothing. If you prefer one of the alternate selections—or if you want no book atall—you notify the Club by returning the card enclosed with each Bulletin.

As a Club Member, you agree only to the purchase of four books (includingyour first selection) over a two-year period. Considering the many books publishedannually, there will surely be at least four you would want to own anyway. Byjoining the club, you save both money and the trouble of searching for the bestbooks.

MAIL THIS COUPON TODAY

COMPUTER PRGFESSIONALS/Book Club

P.O. Box 582 Princeton Road, Hightstown, New Jersey 08520

Please enroll me as a member and send me the two books indicated. I am toreceive the bonus book at the introductory price of $1.89 plus my first selection,plus tax, postage and handling. If not completely satisfied, I may return the bookswithin 10 days and request that my membership be cancelled. If I keep the books,I agree (o take a minimum of Ihree additional books during the next two years atspecial Club prices (guaranteed 15% discount, often more). I will receive theClub bulletin 12 times a year. If I want to examine the featured selection, I needlake no action. It will be shipped automatically. If, however, I want an alternateselection—or no book at all—I simply notify the Club by returning the convenientcard always enclosed. I will always have a minimum of 10 days in which to returnthe card and you will credit my account fully, including postage, if this is not thecase. Membership in the Club is continuous but cancellable by me at any timeafter the four-book purchase requirement has been filled. This order subject toacceptance by McGraw-Hill. Orders from outside the continental U.S. must beprepaid. Company, business, or institutional tax exemption status is not applicableto purchases made through individual Club memberships. All prices subject tochange without notice. Oiler good tor new members only.

Write Code # of $1.89 bonus Write Code # of

book selection here first selection here

NAME.

ADDRESS.CITY

STATE.

_2IP_

EXTRA SAVINGS: Remit in full with your order, plus any local and statetax, and McGraw-Hill will pay all postage and handling charges.

P39186

Artificial Intelligence,An Evolutionary Idea

Part 1: An Overview

Michael Wimble6026 Underwood AvCedar Rapids IA 52404

Artificial intelligence is a subject that hasfascinated people the world over for manyyears, but with the introduction of thecomputer this fascination is becoming areality. I do not mean the intelligencedepicted in so many science fiction booksand sensational movies, but rather the slowand methodical application of computers toperform tasks formerly thought to requireintelligence. To attempt lo even brieflydescribe the areas and techniques of artificialintelligence research would certainly occupyseveral text books. The small computer usercan, however, enter this exciting field andperform personal research and experimentsby using the technique described in thisarticle.

The technique is called "Artificial Intel-ligence Through Simulated Evolution" andits early use and implementation is describedvery well by Fogel, Owens and Walsh in theirbook of the same name, published by JohnWiley and Sons, New York, 1966. I havechosen the technique for several reasons:

1. It can be simple to implement.

2. It is a powerful technique.

3. It is readily programmable on anysmall general purpose system.

4. It gives the user a quick and simpleintroduction to the realm of artificialintelligence.

The criterion just listed represent only thelow end of application of this technique.Indeed some versions of programs using thistechnique perform very sophisticated func-

tions using hundreds of hours of time onlarge computers . . . and even involve the useof artificial intelligence to analyze and op-timize the very artificial intelligence process.

The Simulated Evolution TechniqueWhat It Can Do

Before describing in detail the logic andtheory of the simulated evolution technique,let us look at some early uses which are bothinteresting and will probably also be theinitial uses of the personal computer. Thetechnique is basically a goal directed patternrecognizer. That is, it performs some taskwhose success is dependent on the formationand recognition of patterns. The goal givento early programs was usually to predictsome future event based upon past experi-ence, although some other uses were in theareas of correlation analysis, image enhance-ment and feature extraction.

One example of an early use, which wasmore to debug the program than anythingelse, was to predict prime numbers. Thecomputer was asked whether or not the nextnumber was a prime. It then replied with ayes or no, and was told whether or not ithad predicted correctly. The computer thenremembered this historical data and lookedfor patterns to be used in future predictions.

To show that this technique is not justsome heuristic or statistical method, let'slook at a slightly different but more interest-ing case, that of predicting earthquakes. Inthe prime number example, the goal wassimply to predict whether or not the nextnumber was prime. It was given a very

26

Subsystem "B" makes thecomputer you already havework almost as well asa new Sol-20.

Add it now, and for a limited timewe'll throw in a new module with 2048bytes of preprogrammed PROM or ROMand 1024 bytes of RAM memory free!

Processor Technology s Subsystem "B"puts together the major system elements you needto get your Altair or IMSAI up and running.

You get both RAM and PROM memory,parallel, serial, cassette and video display inter-faces, and software. Software includes a boot-strap loader program so you can load anyProcessor Technology CUTS (''Byte/KansasCity") 1200 BAUD cassette tapes. Standardizedsubroutines in ROM, similar to those in a Solpersonality module, are used by many ProcessorTechnology software packages to improveprogram efficiency. You'll find you rarely need totouch your front panel switches. With ourSubsystem "B" you are up and running as soonas you turn on the power.

Three subsystems are available, dependingon your memory requirements. Each Subsystem"B" includes five S-100 bus compatible modulesas listed below. Each is dependent upon our newGPM module (GPM = General Purpose Memory)which provides 1024 bytes of low power staticRAM and 2048 bytes of preprogrammed ROM orEPROM as well as space for up to 8192 bytesmore of ROM or 2708 type EPROM. The GPMmodule accepts the new ROM version of our wellknownALS-8 Editor/Assembler software package.

With Subsystem "B" you have guaranteedcompatibility with all Processor Technologysoftware and hardware products.

Subsystem Model

B70

B110

B190

Total memoryprovided (bytes)

7168

11264

19456

Display I/O

VDM-1

VDM-1

VDM-1

Parallel, Serial I/O

3P+S

3P+S

3P+S

Tape Cassette I/O

CUTS

CUTS

CUTS

Memory

4KRA

8KRA

16KRA

Price

$594

$730

$964

NOTE: The GPM module with both RAM and PROM

is included FREE in all the above subsystems. The GPM kit

is S129 if purchased separately.

The ALS-8/ROM chip set is $159. SIM-1 & TXT-2/ROMadd-on set is S60 and requires both GPM and ALS-8/ROM.

I want Subsystem "B" to get my Altair orIMSAI up and running.

□ Enclosed is a check for S_

California residents add 6% sales tax.No shipping charge.

□ Mastercharge #

(include Interbank No. andexpiration date)

□ Send more information

Name

I want:

□ B70 at S594

□ B110 at $730

□ B190 at $964

Address.City

. State-

Zip.

Corporation "*^ #

6200 Hollis Street, Box BEmeryville. CA 94608 (415) 652-8080

simple "sense of values" that said making agood prediction was good and making a badprediction was bad. By altering this sense ofvalues, we change the goal.

For earthquake prediction, the goal is asfollows:

• Predict when an earthquake will nextoccur.

• To make a good prediction is verygood and to make a bad prediction isvery bad.

• It is better, however, to predict a falsealarm than to miss an actualearthquake.

Now let's compare the performance of theprogram when given the two different goals.

In the case of prime number prediction,after about the seventh observation theprogram realized that no multiple of twowas prime. After about the seventeenthobservation, the program realized that nomultiple of three was prime. Unfortunately,as the numbers get larger the occurrence ofprimes becomes less frequent, at least for thefirst few hundred numbers. So the programrapidly settled into predicting that the nextnumber will not be a prime, which isstatistically very good.

In the case of earthquake prediction andusing the same data as with the primenumber case (ie: the occurrence of a primenumber is the occurrence of an earthquake),the program acted in a much more sophisti-cated manner. In fact, a correct earthquakeprediction was almost never missed, al-though 10% to 20% of its predictions werefalse alarms.

Finally, let's examine what is perhaps themost fascinating use of the technique: pre-dicting people. One version of the programwas set up as a game. Its goal was to predictwhich thing the opponent was going to donext. The opponent, a human player, wasallowed to do one of two things, such assay true or false. The game was played inreal time and was thus competitive. The goalof the opponent was to be unpredictable.Each time the computer correctly predictedthe opponent I scored a win for the com-puter, otherwise it was a win for theopponent.

The opponent was free to chose anystrategy as long as he was unaided. That is,he could not use random number generatorsor tables or other such aids. He might, forinstance, choose to be as random as possibleright from the start or he might try to use aparticular pattern until he felt the computerhad discovered it and then to use a differentpattern.

One would think that if a person could

make one of two choices, and he/she madechoices purely randomly, then the best onecould correctly predict him/her would be50% of the time. This is true. In practice,however, an unaided human cannot performrandom actions; there is always some patternor at least a bias. Moreover, it seems that aperson in a competitive situation tries tofind the pattern of his/her opponent and tothen develop an antipattern pattern. Oneproof of this, in fact, is the performance ofthe computer. When played against severaldifferent players and requiring at least ahundred predictions before the opponentcould end the game, the computer success-fully predicted the opponent 55% to 85% ofthe time, depending upon the opponent.Typically, 65% of its predictions werecorrect.

The Simulated Evolution TechniqueAn Overview

I will now explain the general functioningof the program, first by analogy and then byactual detail. The analogy may be shockingto some, but bear in mind that it is only ananalogy. I use it because, although it istechnically inaccurate, it helps make theprocess clear and it provides some laymantype concepts and explanations for theactual mathematical processes that occur.

As the name of the technique implies, theprocess involves creating an "organism"which then undergoes evolution. The or-ganism has a survival instinct, and to surviveit must successfully and continually achievea goal. If at any time it fails, it is made toproduce mutated offspring, each slightlydifferent than the parent. These offspringalong with the parent are then compared todetermine which one is best able to achievethe goal, usually based upon historical data.The one best organism is then kept as a newparent and all the rest are destroyed. Thenew parent now survives until the next timeit fails to achieve the goal.

What we then have is the simulation ofthousands of years of evolution in a matterof minutes on the computer. Each organismhas several basic facilities to aid in achievingits goal. It has an .awareness of the goal via amatrix of values which serves both as theevolutionary selection criterion and as asense of values or judgments. It is able tointeract with the environment as in the caseof predicting the environment. Finally, it hasa memory. Some programs allow unlimitedmemory while others may somehow restrictwhat can be remembered. Some programseven allow the organism to choose by itselfwhat it wishes to remember.The importance of memory is well illus-

28

ORDER FORM

KIT

[Write in each box the quantity of each part required]

Kl"

ras

fflOKL.

i,.SErli_S.H

ASSEMBLED4KROM I I

8KSC-Z 1 |

68KSC I I

8KSC I I

ASSEMBLY AND OPERATING MANUAL $4.00

ASSEMBLED16KSC IWWC

88 EXT \ZZ68EXT-S I I

KIT ASSEMBLED

I I 68EXT-LI | 68WWC [

1 BBUC I

NAME.

PLEASE PRINT OR TYPE

ADDRESS.CITY

.STATE.

ZIP.

SEND CHECK • MONEY ORDER • CODS ACCEPTED • CREDIT CARDS

SEALS ELECTRONICS, INCP.O. BOX 11651KNOXVILLE, TN 37919

MOST ORDERS SHIPPED WITHIN 10 WORKING DAYS

I I I II I I ILLULLL

JJLL

II l M I l l I l l l l l l I I

;.-l

JJ!

4KR0M

[READ ONLY MEMORY]

I Will accept up to 16 ea. 1702-A or 5203 EProm Providing up to 4096words of non-volatile memory for Boot Loads to Complete Programs.Programming Available at Factory for $3.00 per EProm when accom-panied by binary formated tape.

I Each 1702-A has its own Vgg clocked for Low Power Consumption.

I Will work with the weakest power supply based S-100 buss computer.

I Switched Selected Address in 4K Blocks.

I Switch selected wait states so that even the slowest 1702-A can workin your system. 0-8 wait states.Solder Masked on both sides of PC Board.

I Component Screened on Component Side of PC Board.

Kit Price: . . $119.00 Assembled Price: . . .$179.00

68KSC

[STATIC MEMORY CARD]

■ 8192 Words of Static Memory

■ Access Time: 500 nsec. (250 nsec on request!

■ Memory Chip 91L02 APC

■ Battery Standby

■ Address Selected 8 Ea. SPST Dip Switch

■ Low Power

■ All Lines Buffered.

■ Ail IC'swith sockets

■ Solder Masked on both sides of PC Board.

Kit Price:

8KSC-Z

$269.00

Assembled Price:

.$359.00

[STATIC MEMORY CARD]

■ ALTAIR®IMSAI®and S-100 buss compatible.

■ Access Time: 250 nsec max.

■ Zilog Speed Compatible up to 4 mhz.

■ Memory Chip: 2102LHPC or 2102-2

■ Battery Standby: >1.5 to 4 volts<

■ Address Select: 8 ea. Spst. Dip Switch.

■ Wait States: None

■ Current Reg.: Less than 200 ma per 1K

■ All Address, Control, and Data out lines fully buffered.

■ All IC's supplied with IC Sockets

■ Solder Masked on Both Front and Back of P.C. Board .

Kit Price: . . $295.00

OTHER SEALS ELECTRONIC PARTS AVAILABLEItem No. Description Kit Price Assembled Price

8KSC 8K Static Memory Card 500 nsec $269.00 $369.00

WWC Wire Wrap Card $ 37.50 $ 47.50

88 EXT 88 Extender Card $ 29.00 $ 38.00

68 Ext-S Extender Card (Small) otcswc,*-....... $ 19.00 $ 25.00

68Ext-L Extender Card (Large) swrTCw»cm.„.,,p »■,«» $29.00 $39.00

68 WWC Wire Wrap Card $35.00 $45.00

BBUC Battery Back-Up Card $ 55.00 $ 68.00

ORDER DELIVERY: FROM STOCK TO 10 DAYS

Assembled Price: . . .$395.00

.SEflLS^-

ELECTRONICS.INC.

TELEPHONE # 615/693-8655

trated by Fogel and his co-authors (page 1):

The distinction between knowledge andintelligence became clear; knowledgebeing the useful information stored with-in the individual, and intelligence beingthe ability of the individual to utilize thisstored information in some worthwhile(goal directed) manner.

These characteristics: goal direction, en-vironmental interaction and memory, whencoupled with one other facet, are responsiblefor the program's "intelligent" behavior. Thesingle most important characteristic of theprogram is that it is self-organizing. It startsout with no preconceived notions. Theprogrammer's own experiences are not re-flected in the programmed organism. Theprogram is not limited to performing only afew particular goals. What does occur is thatthe program is given a goal and the organismalters itself, changing its own makeup inaccordance with its own judgment and ex-perience, always becoming better able toachieve the goal. The goal can be any of awide variety of goals, prediction being onlyone of the simpler goals. The goal can evenchange while the program is running and theorganism will alter itself to meet this newgoal. With this in mind, consider Fogel'soffering of a definition of intelligence (page2):

More carefully stated, intelligence can beviewed as the ability of any decisionmaking entity to achieve a degree ofsuccess in seeking a wide variety of goalsunder a wide variety of environments.

There are few restrictions on the programother than those explicitly or implicitlygiven by the programmer. The restrictionswithin which the programmer must operateare as follows:

1. The amount of computer memoryavailable determines the maximumpossible sophistication of the program.

2. The programmer will usually placelimitations on the evolution process sothat it will stop after some timeperiod. Thus it will not take hours ordays to make the next response.

3. The organism can recognize only afixed number of input observationtypes. For the game described in part2 of this article, the number is two.The amount of computer memoryrequired is related to the square of thisnumber and so seldom is greater than16.

4. The organism can make only a fixednumber of output response types. For

the game to be described the numberis two and is the same as the inputobservation types (ie: the output is aprediction of the next input).5. The program operates sequentially. Itmakes a response, receives feedbackwhich it uses to judge the "goodness"of its previous response, and reorga-nizes itself to make the next response.

The Simulated Evolution TechniqueDetailed Representation

The actual program uses what is called astate space mathematical model. The modelconsists of a set of five elements thus:

s},{l|,{0},{T},f}

where:

•jS Ms a set of states

■jljis a set of input symbols (inputalphabet)

jOfis a set of output symbols (outputalphabet)

JTJ is a set of transitions

f is the current state

The brackets " J >" denote sets, a notion oftenfound in mathematical texts.

As an example, figure 1 represents ahypothetical model for a stock investor. Thecurrent state, f, is state X. The model says:The model is at state X and if the marketprice of the stock goes up (symbol U) thenthe investor will sell a block of the stock(symbol S) and go to state Y; otherwise ifthe market goes down (symbol D) then theinvestor will buy a block of the stock(symbol B) and go to state Z. This isrepresented in figure 1 as:

u/s

Assume that the market had gone up inthe previous example, the current statewould now be Y and if the market price ofthe stock were to now go down the modelsays that the investor would buy a block ofstock and remain at slate Y. In figure 1 thisis represented by:

D/B

30

PRIME RADIX

PRESENTSTHE

WE DO IT WITH MIRRORS!

(and some very sophisticated state-of-the-art memory design)

65,536 BYTES

Your dream can be a reality with the Prime Radix Corporation's64Ktm memory system at a very cost-effective price. Andbecause it is a standalone memory system, you've got theadvantage of greater flexibility not ordinarily available fromadd-in memory. Some of the features are:

• The 64Ktm is fully buffered, presenting one TTL load to thememory bus.

• The 64Ktm is digital group bus and ALTAIRtm buscompatible When ordering, you must specify the busarchitecture. A plugcard and cable will be furnished for theparticular bus architecture you specify.

• The minimum complement of memory is 40K BYTES, withstarting address locations at OK, 8K, 16K, or 24K.

• The 64Ktm comes assembled and tested with its own powersupply, attractively housed in an aluminum cabinet, ready toplug into your system.

• Psuedo-static operation: on board refresh clock-generatorprovides processor independent refresh with no wait states.The 300NS worst case access time enhances high speedoperation.

• Power/fail detection circuitry and battery backup willprovide non-volatile memory (batteries are optional at extracost).

LIST PRICE IS AS FOLLOWS:

40K 48K 56K 64K

S1490.00 $1580.00 $1670.00 $1750.00

Delivery will be made in the same sequence as orders arereceived. Please allow 3 to 6 weeks for delivery. Masterchargeand BankAmericard are accepted.

PRIME RADIX • P O Box 11245 • Denver Colorado 80211 • (303) 573-5942^01^33^5630

□ DIGITAL GROUP BUS

□ ALTAIRtm BUSD 64K @ $1750.00

□ 56K @ $1670.00

□ 48K @ $1580.00

□ 40K @ $1490.00

PRIME RADIX

COMPUTER SYNTHESIS

Print Name

lake checks or money orders payable to:

PRIME RADIX. INC.P.O. Box 11245Denver. Colorado 80211(303) 573-5942 or 433-5630

Credit Card Number

Address

City

State

Zip

□ Check or MO. enclosed

□ Charge BACD Charge MC

(Please No C.O.D.'s or P.O.'s)

4 Numbers Above Name (MC)Good Thru

Signature

J

31

u/s

S) ■ {X,Y,z||}-{U.D)

°h (b.s)

T) > (SEE TEXT}

f = x

Figure I: Hypotheticalstate space model of astock investor. The lettercodes U and P stand forthe up and down fluctua-tions of the stock marketprices. The letters B and Sstand for the buying andselling of stock. The set Tis the set of all the transi-tions of the model.

For our pictorial representation of a statespace model we have a set of states which isrepresented by the circles. The set of transi-tions is represented by the arrows. Alongsideof each transition arrow is a pair of symbolsseparated by a slash. The symbol to the leftof the slash is a symbol from the inputalphabet and says that if the model iscurrently at the state connected to the tailof the arrow and this input symbol occurs,then this transition is to be taken. Thesymbol to the right of the slash is a symbolfrom the output alphabet and says that ifthis transition is taken, as per the previousstatement, then this symbol is to be outputand the new current state is the stateconnected to the head of the arrow.

State Space and Evolution

Given a state space model, we now lookat the evolution process. There are five basicways we can change the model; we can:

1. Add a new state (change theset JS} ).

2. Remove an existing state (change theset |s|).

3. Change (repoint) a transition (changethe set |t| ).

4. Change the current state (change f).

5. Change an output symbol for atransition.

Changing an input symbol is not allowed.Every state must have exactly as manytransitions projecting from it as there arepossible input symbols. Thus when at aparticular state there is a valid response forevery valid input.

Note that the set of input and outputsymbols cannot be changed during the runof a program. Technically there are ways ofallowing this change but the programmingbecomes highly complex, so we assume thatall possible observance types and all possibledesired response types are known when theprogram begins, fin programming, as in

physics or math, this is what is called a"simplifying assumption. "J

Also, change type five is really notsomething that needs to be done randomly.There is a technique called deterministicoptimization that assures that the outputresponses are the best possible for a givenmodel. There is, however, a desirable changewhich can replace change type five and willbe explained at the end of the next section.

The State Space Modelas an Intelligent Organism

There are some interesting properties ofthe state space models that get developed viathis simulated evolution. The first is thetolerance to noise. Also, the model is able torepair damage to itself. Finally, if the modelis knocked out of synchronism with theenvironment it quickly locks back intosynchronism.

When the model is given the goal to find apattern, it may be constrained by the pro-grammer or may have decided on the basisof previous inputs that the pattern for whichit is searching is a simple pattern. Theenvironment may then contain high levels ofrandom signals (noise) but the model willautomatically ignore these random elements,deciding that their pattern is too complex. Itwill then lock onto the underlying patternedsignal and thus remove it cleanly from thenoise.

If the model is suddenly damaged, such asby loss of power in a memory module, oreven by programmed destruction of a stateor a transition, the model tends to "heal"itself as new data is collected. It just sohappens that the model is always striving tobe a perfect representation of the environ-ment. If this representation is changed,equivalent, say, to a person losing a leg, thenthe evolution process will tend to restore thedamage to regain that optimum representa-tion.

A common problem that does exist fromthis method of artificial intelligence is theloss of synchronism with the environment.What may be an otherwise perfect modelmay consistently yield incorrect predictionssimply because it started out at the wrongstate. Fortunately, as with the other prob-lem types, the model has a tendency to lockitself back in synchronism with the environ-ment. Since, however, this problem canoccur for so many reasons, we opt toprovide an evolutionary function to speedup this lock. We then replace the old changetype five with a new type, "advance thecurrent state ahead by one state." We are

Continued on page 44

32

HOW CAN YOU MAKE YOURZ80 SYSTEM RIVAL THE EXPENSIVEPROFESSIONAL MINI-SYSTEMS?

# BY ORDERING TDL's ADVANCED_ INTEGRATED SYSTEM SOFTWARE.

• TODAY.

••...•

;;:«;««*.

.V.". .-••• ••;V*iM*t«»i«

ALL TDL SOFTWARE IS RELOCATABLE.

THE ZAPPLEMONITOR

The versatile Zapple Monitor maximizes theuser's system executive control. All I/O driv-ers for all TDL software are contained in theMonitor; once the Monitor is modified toyour I/O configuration all other TDL softwareis immediately compatible with your systemmaking your total system setup extremelysimple.

Trie Monitor supports a CRT, teletype andaudio cassette as well as providing exception-ally powerful hardware and software debug-ging capability. It's modular organization alsoallows other user provided I/O drivers to be'tacked on' at the end to handle any form ofI/O your system may demand. The Monitor's27 commands occupy only 2K of core. A de-scription of the command set requires morespace than available here.

Coupled with TDL's other software, yoursystem attains the highest level system integ-ration available for a micro-processor. $25

THE RELOCATINGMACRO ASSEMBLER

Here is the most sophisticated program-ming tool yet developed for a micro-processor. It is without equal in terms ofnumber of functions, scope of capabilitiesand usefulness.

• It generates a fully relocatable object code.

* It has complete macro generation and infi-nite nesting of macros capability.

TDL's ingenious Z80 opcode set has as asubset the same opcodes as the 8080. Whereother Z80 functions resemble 8080 functions,the TDL mnemonics are logically derived forease of learning. Where our Z80 opcodeshave no 8080 parallel, we generally use Zilogopcodes. Your current 8080 source can bereassembled with only nominal text editing.

$50

ZAPPLEBASIC

The most complete and innovative HK Basicinterpreter written. Highly compatible withother Basics. Unique Features include:

TRACE: Allows switching among variousline numbers during execution.

SWITCH: Allows switching among variousI/O devices either in the program or from thekeyboard.

RENUMBER: Allows upward or downwardrenumbering of the numbered line state-ments.

LVAR: Lists program variables and theirvalues on your command.

LLVAR: Same as LVAR, but outputs the in-formation to your hardcopy device.

EDIT: A unique feature in an 8K Basic. Al-lows you to change the internal structure of aline with the 'delete' command.

ZAPPLE BASIC is unique versatile andpowerful and up to 20% faster than compara-ble Basics. $50

TEXT OUTPUTPROCESSOR

TDL's general purpose word processor forthe Z80. Used in conjunction with the TEXTEDITOR and MONITOR, it occupies 3K ofcore and provides powerful word-processingcapability.

TDL's TOP features automatic paging, con-catenation and justification, as well as manyother formatting functions.

Straightforward entry of the Processor'snumerous commands directly into the textputs you in total control. The output from theEditor is then run through the Processor toproduce output exactly as you have com-manded.

Imagination alone limits the possible appli-cations of this word-processor. $50

SUPERBASIC

Our powerful new 12K Basic Interpreter hasall the features of Zapple 8K Basic, plus theseadditions, and many others:

• Allows eleven digit precision including allbuilt-in functions as well as SIN andARCTAN.

■ Multi-line recursive user defined functions.

■ Sophisticated editing and program loading.

■ Statements may be tabbed horizontallyand/or spread over successive lines.

• AUTO inserts line numbers automaticallyinto your program.

• A PRINT USING statement is includedwhich allows the format to be specified as toeither a string or a statement number.

■ EXCHANGE interchanges the values of twovariables at high speed.

■ LOADGO allows one program to call in andto execute another program.

■ CALL allows you to call resident assemblylanguage subroutines with any number ofnumeric arguments.

SUPER-BASIC does much more and qual-ifies as the finest Basic available for micro-processors. $95

THE ZAPPLETEXT EDITOR

This omnipotent tool gives you the ability tocreate or to change assembly language pro-grams and to facilitate general word process-ing.

Text lines and characters may be located,inserted, deleted or changed at will in eitherforward or backward directions via a movableinternal pointer.

Control may be effected by 24 alpha nu-meric commands which may be strung to-gether in macro-like statements yieldingsuperlative editing capability. $35

PACKAGE A - THE BASIC & SUPERBASIC PACKAGE: Consists of the Zapple Monitor, Zapple

Text Editor, Macro Assembler, The Text Output Processor and either"8K Basic @ $ 169

or Super Basic @ $ 199

PACKAGE B - THE WORD-PROCESSING PACKAGE: Consists of the Zapple Monitor, the Text

Output Processor and the Zapple Text Editor $

PACKAGE C - THE SOFTWARE DEVELOPMENT PACKAGE: Consists of the Zapple Monitor,

Zapple Text Editor and the Relocating Macro-Assembler $

All TDL Software is supplied on paper tape in relocatable hex format along with TDL's com-prehensive User's Guides and Manual. Write for prices on disk or cassette media.

ORDERING INFORMATION: Send check, money order or BankAmericard, Master Chargecurrent number and expiration date. Shipment is usually made via UPS or UPS Blue Label.Specify other arrangements if you wish. Prepaid orders are shipped postpaid.

Contact us for hardware systems as well.Distribution Rights Available.

TECHNICAL

DESIGN

LABS

RESEARCH PARK BLDG H 1101 STATE ROADPRINCETON. NEW JERSEY 08540 (609) 921-0321

85

85

System Description

Photo 1.' A color test chartshowing the 15 shades ofhue available from theApple-11 as presented on atypical commercial colorset, using one of severalRF modulators availableon the market. The AppleBASIC program used togenerate this color isshown in the text portionof this split screen(graphics and text)display.

The Apple-H

Stephen Wozniak

Apple Computer Co

20863 Stevens Creek Blvd B3-C

Cupertino CA 95014

To me, a personal computer should besmall, reliable, convenient to use and inex-pensive.

The Apple-I, my first video orientedsingle board computer, was designed late in1975 and sold by word of mouth through-out California and later nationwide throughretail computer stores. I think that theApple-I computer was the first microproces-sor system product on the market to com-pletely integrate the display generation cir-cuitry, microprocessor, memory and powersupply on the same board. This meant thatits owner could run the Apple BASICinterpreter with no additional electronicsother than a keyboard and video monitor.The Apple-I video computer board wasoriginally intended as a television terminalproduct which could also operate in a standalone mode without much in the way ofmemory, although it did have a processor,

space for 8 K bytes of 4 K dynamic memorychips, and its shared video generation anddynamic memory refresh logic. Apple-I wassold as a completely assembled and testedprocessor board with a price under $700 atthe retail level.

The latest result of my design activities isthe Apple-I I which is the main subject ofthis system description article. The Apple-I Ibuilds upon this idea by providing a com-puter with more memory capability, a readonly memory (ROM) BASIC interpreter,color video graphics as well as point graphicsand character graphics, and extended sys-tems software.

Integral Graphics

A key part of the Apple-I I design is anintegral video display generator which di-rectly accesses the system's programmable

34

memory. Screen formatting and cursor con-trols are realized in my design in the form ofabout 200 bytes of read only memory whicharc built into the Apple-ll's mask pro-grammed 8 K bytes of read only memory. AI K byte segment of the processor's mainmemory is dedicated to the display gener-ator, although it is also accessible to pro-grams. The display transfer rate is the time ittakes to fully define the contents of thissegment of memory, and averages about1000 characters per second, limited pri-

marily by the software scrolling routines inthe system read only memory.

Since the Applc-ll incorporates this dis-play generator as a part of its design, its textmode becomes the terminal for the system.The display has 24 rows of 40 charactersdisplayed on an ordinary black and white orcolor television screen. Each character in theApple-I I design is a 5 by 7 dot matrix, so thepresent version of the system only imple-ments upper case characters of the 6 bitASCII subset, as well as the usual numbers

VIDEO GENERATOR / MEMORY / PROCESSOR TIMING AND CONTROL

VIDEO

GEN. ADDR*

PROCESSOR I ADDR*

4>| , ROW ORCOLUMN SELECT

ADDRESS

PROGRAMMABLEMEMORY

(4K TO 48K BYTES)

?s

"ROW AND COLUMNADDRESSES

PROCESSOR

I

MEMORYDATA

IN

BIDIRECTIONAL SYSTEM BUS

MEMORYJ DATA OUT

"MUX" = MULTIPLEXER

VIDEO MODE CONTROL

TIMING:

6502 PROCESSOR'S♦ l CLOCK SHOWINGWHEN AND BY WHOMMEMORY IS ACCESSED

* - li

PHASESHIFTER

CHARACTERGENERATOR

^ SERIALIZER

\ r

VIDEO ACCESSAND MEMORYREFRESH

PROCESSORACCESS ANDPROGRAMEXECUTION

COLORGENERATOR

J SERIALIZER

SERIAL

VIDEO

(GRAPHICS)

\

SERIAL

VIDEO

(CHAR)

COLORVIDEO

SIGNAL

SOFTWARECONTROLLEDVIDEO MUX

EIA

VIDEO

OUT

I

Figure 7 / A block diagram of the Apple-I I display generator. The generator sneaks in to memory on the externally unused phaseof the 6502 processor's 2 phase clock. The output of the memory is processed (after a I clock cycle delay) to produce a netvideo output through a software controlled video multiplexer. The three major modes of operation are:

Color graphics, in which each 4 bit nybble of the byte is treated as a color definition code by the color generator.

Character generation in which the 8 bit code is processed with a read only memory to generate a dot matrix pattern whichis serialized and sent to the video multiplexer.

Black-white point graphics in which the 8 bit word from memory is used to control the contents of a segment of a 280 by160 point grid.

The timing diagram shows how the basic I [is processor cycle period is split up into a video memory cycle and a microprocessormemory cycle. Since the processor is engaged in internal housekeeping operations during the first (high level) half of a $7period, this segment of time can be used by the video generator to sneak into memory. Since all of memory is continuouslybeing scanned by the low order bits out of video generator, the entire 48 K byte field (maximum) of dynamic memory isrefreshed by the video portion of the cycle. (Refreshing of dynamic memory means scanning through all possible low orderaddresses to recharge the internal memory capacitors of the chips.)

35

THE BASIC

SOFT

JBRARY ^bRxRv x^

lU

»»OW*

The "HOW-TO-DO IT"Books for the "DO-IT" Person

Available NOW! ! ! at most computer stores

* #

ARIZONAByte Shop of Phoenix-WestPhoenix, AZ 80529(602) 942-7300

Byte Shop of PhoenixTempe, AZ 84281(602) 894-1129

Desert Data Computer StorePOB 1334Tucson, AZ 85702Gary Miller & Bud Ward

CALIFORNIAByte Shop of LawndaleLawndale, CA 90260(213) 371-2421

The Computer StoreSanta Monica, CA 90401(213) 451-0713

A-VID ElectronicsLong Beach, CA 90806(213)426-5526

Byte Shop of PasadenaPasadena, CA91101(213) 684-3311

Byte Shop of TarzanaTarzana, CA 91356(213) 343-3919

Byte Shop/Thousand OaksThousand Oaks, CA 91360(805) 497-9595

Computer ComponentsVan Nuys, CA 91411(213) 786-7411

People's Computer ShopSherman Oaks, CA 91423(213) 789-7514

Upland Computer LabsUpland, CA 91786(714) 981-1503

Byte Shop of San DiegoSan Diego, CA9211117141 565-8008

Byte Shop of WestminsterWestminster, CA 92683(714) 894-9131

The Computer MartOrange, CA 92667(714) 633-1222

Byte Shop of Santa BarbaraSanta Barbara, CA 93101(805) 966-2557

Byte Shop of San Fernando

Valley

Tarzana, CA 93156

1213) 343-3919

Byte Shop of Fresno4131 E. McKinley AveFresno, CA 93703

Byte Shop of Mountain ViewMt. View, CA 94040(415)969-5464

Byte Shops, Inc.Sunnyvale, CA 94086(408) 734-9000

Byte Shop of Palo AltoPalo Alto, CA 94306(415) 327-8080

Byte Shop of San MateoSan Mateo, CA 94430(415) 341-4200

Byte Shop of HaywardHayward, CA 945411415) 537-BYTE

The Computer ShackSan Leandro, CA 94577(4151895-9363

Byte Shop of Diablo ValleyWalnut Creek, CA 94596(415) 933-6252

Byte Shop of BerkeleyBerkeley, CA 94703(415) 845-6366

Byte Shop of San RafaelSan Rafael, CA 94901(415)457-9311

Byte Shop of Santa ClaraSanta Clara, CA 95051(408) 249-4221Byte Shop of San JoseSan Jose, CA 95123(408) 226-8383

Byte Shop of CampbellSan Jose, CA 95124(408) 377-4685

Byte Shop of SacramentoCitrus Heights, CA 95610(916) 726-2557

Computerworld Stores1309 Court StreetRedding, CA 96001William J. Fraser

COLORADOByte Shop/Arapahoe Co.Englewood, CO 80110(303) 761-6232

CONNECTICUTThe Computer Store63 South Main StreetWindsor Locks, CT 06096

FLORIDA

Williams Radio& TV, Inc.Jacksonville, FL 32206(904) 354-5460

Byte Shop of Cocoa BeachCocoa Beach, FL 32931(305) 784-1881

Computer Hut

Miami Lakes, FL 33014

(305) 821-2667

Micro Computer Systems &

Sales

Pompano Beach, FL 33068

(305) 972-6093

The Computer HutDenver, CO 80202(303) 573-4895

Byte Shop of BoulderBoulder, CO 80301(303) 449-6233

Byte Shop of MiamiMiami, FL33155(305) 264-BYTE

Micro Computer Systems IncTampa. FL 33609(8131 879-4301

ILLINOISAmerican MicroprocessorEquipment & Supply Corp.Prairie View, IL 60069(312) 634-0076

INDIANAGraham ElectronicsIndianapolis, IN 46204(317) 634-8202

The Home Computer StoreIndianapolis, IN 46204(317) 894-3319

The Data DomainBloomington, IN 47401(812) 334-3607

Computer SpecialistsW. Lafayette, IN 47906(317) 743-1711

KENTUCKYThe Data DomainLexington, KY 40502(606) 233-3346

MARYLANDComputer WorkshopRockville, MD 20852(301) 468-0465

Science Education Ext. Corp.Potomac, MD 20854(301) 299-9506

MASSACHUSETTSComputer Mart, Inc.Waltham, MA 02154(617) 899-4540

Computer WarehouseBoston, MA 02215(617) 261-2701

MINNESOTAByte Shop of EaganEagan, MN 55121(612)452-1841

MISSOURIComputer Systems Center ofSt. Louis Inc.Chesterfield, MO 63071(3141 576-5020

Computer WorkshopKansas City, MO 64152(816) 741-5055

NEW HAMPSHIREComputer Mart of NHNashua, NH 03060(6031 883-2386

Microcomputers Inc.Nashua, NH 030601603)889-1646

NEW JERSEYHoboken Computer WorksHoboken, NJ 07030(201)420-1644

The Computer Mart ofNew Jersey501 Route 27Iselin, NJ 08830

NEW YORKThe Computer Mart ofNew York

New York, NY 10001(2121 279-1048

Synchro-Sound EnterprisesHollis, NY 11423(212) 468-7067

Computer Mart of Long

Island

East Meadow, NY 11554

(516) 79400

(516) 794-0510

Byte Shop of LevittownLevittown, NY 11756(516) 731-81 16

New YorkMini Micro MartSyracuse, NY 13203(315) 422-4467

OHIO

Digital DesignCincinnati, OH 45243(513) 561-6733

OKLAHOMAHigh TechnologyOklahoma City, OK 73116(405) 842-2021

OREGONByte Shop of BeavertonBeaverton, OR 97005(503) 644-2686

Byte Shop of PortlandPortland, OR 97201(503) 223-3496

PENNSYLVANIAByte Shop of Bryn MawrBryn Mawr, PA 190101215)525-7712

Personal Computer Corp.Frazer, PA 19355(215) 647-8460

RHODE ISLANDComputer Power Inc.Warwick, Rl 02886(401) 738-4477

SOUTH CAROLINAByte Shop of ColumbiaColumbia, SC 29205(803) 771-7824

TENNESSEEByte TronicsNashville, TN 37203(6151329-1979

Micro Computer SystemsKnoxville, TN 379221615] 966-9849

TEXAS

Micro StoreRichardson, TX 75080(214) 231-1096

K.A. ElectronicsDallas, TX 75247(214) 634-7870

ElectrotexHouston, TX 77006(713) 526-3456

Altair Computer CenterHouston, TX 770361713) 780-8981

Interactive ComputersHouston. TX 77036(713) 781-2703

The Computer ShopVanguard Systems6B12 San PedroSan Antonio, TX 78216

Southwest Technical

Products Corp.

POB 32040

San Antonio, TX 78216

Gary Kay

UTAHByte Shop/Salt Lake City216 S. State St.Salt Lake City, UT84111Bob Bollinder

VIRGINIAShire EnterprisesRichmond, VA 23222(804) 321-4560

Virginia Computer HobbiesUnlimited

Richmond, VA 23235(804) 276-5056

WASHINGTONAlmac/Strom ElectronicsSeattle, WA 98108(206) 763-2300

WISCONSINThe Milwaukee ComputerStore

Milwaukee, Wl 53213(414) 259-9140)

Microcomp

Fond Du Lac, Wl 54935

(414) 922-2515

CANADATrintronicsToronto, OntarioCanada M5V 1Z1(416) 598-0262

Byte Shop of VancouverVancouver 9 B.C.(604) 736-7221

The Pacific Computer StoreVancouver, B.C. V6R 2J4(604) 438-Data

JAPANByte Shop of Tokyo2-9-9 StotdandaChiyodaka, TokyoKiyotake Ikeda

WARE

LIBRARY

This LIBRARY is a complete do it yourself kit. Knowledge of programming not required. EASY to read and USE

Written in compatible BASIC immediately executablecomputer with at least 4K, NO other peripherals needed.

in ANY

This Library is the most comprehensive work of its kind to date.There are other software books on the market but they arededicated to computer games. The intention of this work is to allowthe average individual the capability to easily perform useful andproductive tasks with a computer. All of the programs containedwithin this Library have been thoroughly tested and executed onseveral systems. Included with each program is a description of theprogram, a list of potential users, instructions for execution andpossible limitations that may arise when running it on varioussystems. Listed in the limitation section is the amount of memorythat is required to store and execute the program.

VOLUME I

BookkeepingGamesPictures ....

$24.95

VOLUME II

Math & EngineeringPlotting & StatBasic Statement Def

$24.95

Each program's source code is listed in full detail. These source codelistings are not reduced in size but are shown full size for increasedreadability. Almost every program is self instructing and promptsthe user with all required running data. Immediately following thesource code listing for most of the programs is a sample executedrun of the program.

The entire Library is 1100 pages long, chocked full of programsource code, instructions, conversions, memory requirements,examples and much more. ALL are written in compatible BASICexecutable in 4K MITS, SPHERE, IMS, SWTPC, PDP, etc. BASICcompilers available for 8080 & 6800 under $10 elsewhere.

This Library is destined to become one of the reference bibles forthe small computer field, due to its versatility and uniqueness andthe ease of operation of the programs it contains. These volumes aredeductible as a business expense when purchased by a company.Send your remittance for prompt delivery, while supplies last.Volume discounts are available to qualified dealers.

VOLUME III

Advanced Business

Billing

Inventory

Payroll

$39.95

VOLUME IV

General Purpose $9.95

VOLUME V

Experimenter $9.95

FUTURE ADDITION TO THE "BASIC SOFTWARE LIBRARY"

Volume VI (A Complete Business System - S49.95) General Ledger System - Taxes, Pyrl,W-2's, Inventory, Depr., Financial Statements, etc. AVAILABLE MID SUMMER

©

Add $1.50 per volume for postage and handling.

SCIENTIFIC RESEARCH

1712-B FARMINGTON COURT

CROFTON MD 21114

Phone Orders call (800) 638-9194

Information and Maryland Residents Call (3011-721-1148

Photo 2: This series of photos showsthe steps in writing an animatedBASIC game using the Apple-// com-puter's BASIC interpreter. This se-quence highlights the process ofwriting a paddle versus "wall" gamewhere the object of play is to knockbricks out of the wall and eventuallyget the ball to go all the way through.This game is similar to many seen inamusement parks and arcades, and istypical of the kind of game which canbe implemented with Apple-/1's BA-SIC software. Using the split screengraphics and text display mode, theBASIC statements are shown at thebottom of each picture.

Photo 2a: The first step in any game isto generate the uniform color back-ground for the action of the game.Here we use a blue field.

and graphics available in standard charactergenerator read only memory parts. Assumingthat the video display is the currentlyassigned system output device, the display isaccessed through our system software inread only memory by using a subroutinecalled COUT which adds text to the screenusing an automatic scrolling technique. Thisis typical of the many read only memoryroutines which I've incorporated into theROM to provide complex features withrelatively simple user interfaces. Anotherexample of such a software feature is a userdefinable scrolling window. This means thatthe user of the system can pick any of fourcoordinates defining any rectangular subsetof the viewing area of the video screen as thecurrent scrolling zone. The remainder of thedisplay will remain frozen and data in thewindow will scroll normally when COUT isaccessed. This is a most useful feature: Forexample, the user can set up a game back-ground or instruction menu in one part ofthe screen while using the remainder of thescreen for scrolling the variable data.

In the text mode, each character positionmay be displayed in normal (white characteron black background) or inverse, or flashingmodes. This information is specified by thehigh order bits of each character stored inthe display memory. The cursor position, forexample, is indicated by forcing the charac-ter at the cursor location to be in theflashing mode with inverse video.

User application programs may switch thedisplay mode from character to color graph-ics with a single instruction, dividing thescreen instantly into a patchwork of con-trollable color on a grid of 40 horizontallocations by 48 vertical locations. Each cellin the grid may be one of 15 colors, andsoftware built into the system read onlymemory can be used to define the color of

Photo 2b: Then we must add a liberaldose of obstacles and field pieces tomake the problem interesting. For thisgame, the major obstacle is a brickwall of orangish (color 13) and green-ish (color 12) bricks. Later on, sincewe can look at the contents of thescreen directly, the game algorithmwill be manipulating these bricks.

any point as set by X and Y coordinateinteger values. Photo 1 shows a color scalefor the 15 colors possible, and a simpleBASIC program which generated the display.Here the scrolling window features are usedto set the color graphics mode in the fixedportion of the screen (above) and set thetext mode of operation in the scrollingportion (below). This mixed mode providesa 40 by 40 color graphics grid plus four linesof scrolling text at the bottom of the screen.A routine in the system read only memoryselects this mode and sets up the scrollingwindow corresponding to the text portion.I've found this mode especially useful toBASIC programmers who can write anima-tion games like Pong while holding a tradi-tional BASIC conversation in the text regionof the screen. This split screen mode ofviewing is used for all the color graphics ofphoto 2 as well.

The same display memory region that isused for the text display is used for the colorgraphics. System software routines suppliedin the read only memory of the processorallow users to simply clear the display, selectcolors, plot points, draw horizontal andvertical lines, and sense the color valuespresently at specified screen positions. I liketo think of these system software subrou-tines as enhancements to the 6502 instruc-tion set for the purposes of display control.

High resolution graphics is the remainingApple-ll display mode. This mode of displayis set up by system software routines whichare delivered with the computer, but are notbuilt into the system read only memory.(Even with 8 l< bytes for the read onlymemory space, there sometimes isn't enough

38

Photo 2c: Next, we must of courseadd a paddle, here created with adeeper yellowish orange (color 9) hue.

Photo 2d: Then, since no video courtgame is complete without a ball wemust add a square "ball" to theprogram, and set up some of theparameters of its motion.

room to fit all the needed features.) In thehigh resolution mode, 8 K bytes of mainmemory store the data for a display of280 horizontal dot positions by 192 verticaldot positions; so to allow enough room forsome BASIC software to play games withthis mode the system requires at least 12 Kof memory. If a color television is used withthis high resolution mode, the availablecolors are black, white, violet and green. Amixed mode with 160 rows of 280 dots plusfour lines of scrolling text can also be set up.Applications of the high resolution graphicsmodes include game boards, mazes, maps,plots and histograms, user definable char-acter sets, and games like Space War in itsoriginal animation graphics versions.

Some Details

All the Apple-ll video modes work iden-tically, using a common clock timing chainwhich is shared by the processor, memoryrefresh and video generation logic. Duringeach microprocessor clock cycle's $-| clockpulse, an address is specified by the videocircuits and directed to the programmablememory of the system through the addressmultiplexor (MUX) of figure I. Display datais received by the three forms of video datagenerators toward the end of the <J>2 pulse,and this data is then latched for use duringthe entire next clock cycle. Since all thisaction occurs during the <J>i pulse whichlasts 500 ns, the video generator is able totake over the access to the memory at a timewhen the 6502 processor is busy withinternal housekeeping and processing opera-tions which leave the data bus free. Duringthe $2 pulse, when the processor takescommand of the bus, the programmablememory of the system is used by theexecuting program as if the video generator

didn't exist at all. Because the integrateddisplay design uses this direct memory accesstechnique without stealing processor cycles,it is possible to program accurate and pre-dictable timing loops in software as if noDMA were present in the system.

Memory

It is alleged in the Santa Clara (Silicon)Valley that the microprocessor was inventedto sell programmable and read only memorychips. It certainly has been the case that onemicroprocessor in the past would oftensupport hundreds of memory chips, buttimes change. Technology has sincebestowed upon us the 4 K bit and 16 K bitdynamic programmable memory chips.

Apple-ll was designed to operate with the16 pin dynamic programmable memoryparts, which come in 4 K and 16 K versionswhich are (with some subtleties) pin for pincompatible.

The Applc-ll board is supplied withsockets for three blocks of memory, each ofwhich may be configured to use either 4 Kor 16 K dynamic programmable memoryparts, with intermixing allowed. This meansthat if you were to purchase an Apple with4 K bytes of memory and later want to add16 K bytes, there is no need to scrap the 4 Kchips.

Dynamic memories have one designcharacteristic which is not present in thesimpler (but more expensive) static memo-ries. This is the fact that they use capacitivestorage elements built into the chips whichmust be periodically recharged ("re-freshed") to prevent the information fromdisappearing.

One of the elegant simplificationsprovided by a system such as the Apple-llwith its built-in display is the fact thatrefreshing the entire memory address

Photo 2e: Finally, the laststeps in finesse are thescore displays and relatedcaptions which completethe game. This game iscontrolled by using one ofthe analog inputs of theApple-ll to determine theindex of the current loca-tion of the paddle, so thatby twisting the pot thepaddle is moved; thespeaker output is used togenerate a sound burstwhen the ball hits the pad-dle or wall.

39

(a)

(b)

>LIST

5 DSP APPLE10 FOR 1=1 TO 1020 IF I>5 THEN 4038 APPLET GOTO 5840 APPLE=180+I50 NEXT I68 PRINT "DONE"■ END

>RUN

#38 APPLE=1#30 APPLE=2#30 APPLE=3#38 APPLE=4#30 APPLE=5#40 APPLE=106#40 APPLE=107#48 APPLE=108#40 APPLE=109#48 APPLE=118

>LIST

10 FOR I2A TF I>30 APPLE48 APPLE50 NEXT68 PRINT

>RUN

-I' GOTO 50

DONE

>TRACE

>RUN

#10 #20 #36#30 #50 #10#10 #20 #40#40 #50 #10#60 DONE

>

#50 #10 #20 #30 #58 #10#20 #38 #50 #16 #28 #30#50 #10 #20 #40 #59 #10#20 #40 #50 #10 #20 #40

#20#50#20#58

>■

Photo 3: Two examples of the Apple BASIC interpreter, in the form of programs with several lines of execution results, (a) Theinterpreter has a symbolic trace feature which allows dumping of named variables whenever a change occurs. This simpleprogram illustrates this "DSP" command with a simple computational program, (b) A similar debugging feature of SteveWozniak's Apple BASIC interpreter is a method of running the interpreter with a statement number trace, by giving a TRACEcommand instead of RUN in the command mode of the interpreter. This enables one to fairly quickly debug a BASIC programby examining its effect on variables or its course of evolution through statement numbers.

space of dynamic memory chips is inherentin the operation of the video display genera-tor. On successive pulses of the video dis-play, it cycles through all the low orderaddresses of the memories as the memory isscanned to generate the video image. Butscanning through the addresses within themaximum allowable time is the algorithmused to accomplish the required refreshingof the memories; so with this video genera-tor integral to the computer, refreshing ofthe memories happens to come for free andis totally transparent to the user with noextended, missing or delayed cycles. Thischaracteristic is sometimes called "hiddenrefresh."

Standard Peripherals

I designed the Applc-ll to come with a setof standard peripherals, in order to fit myconcept of a personal computer. In additionto the video display, color graphics and highresolution graphics, this design includes akeyboard interface, audio cassette interface,four analog game paddle inputs (for usersupplied potentiometers which vary a re-sistance which the processor measures),three switch inputs, four 1 bit annunciatoroutputs, and even an audio output to aspeaker. Also part of the Apple-ll design isan 8 slot motherboard for IO which has afully buffered bus, prioritized interrupts,two prioritized direct memory access (DMA)schemes, and address decoding at the indivi-

dual slots so that multiple bit address de-coders are not required on peripheral boards.

The Apple-ll cassette interface is simple,fast, and I think most reliable. The datatransfer rate averages over 180 bytes persecond, and the recording scheme is com-patible with the interface used with theApple-I. This tape recording method can beused with any inexpensive recorder, but aswith any such use of audio media only highquality tapes should be used in order toavoid problems due to dropouts from pooroxide coatings on the tapes. In the Appleaudio cassette interface, timing is performedby software which is referenced to thesystem clock. A zero bit is defined as a fullcycle of a 2000 Hz signal (500^s long), whilea one bit is defined as a full cycle of a1000 Hz signal (1 ms long). While reading data,full cycles are sampled, never half cycles, amethod which tends to provide immunity toDC offset and other forms of distortion. Allthe cassette management routines are avail-able to user programs as subroutine callsfrom assembly language directly, or throughhooks in the BASIC interpreter.

The Apple-ll analog game control paddlecircuits are based upon inexpensive timerchips of the 555 type. I've used a quad timerof this type, called the 553, as shown infigure 2. To read the value of resistance onthe paddle's potentiometer, the timer isstrobed under software control using rou-tines in the system read only memory. The

40

(a)

(b)

*F788L

F788-

F9

4C CF

SBC

$CF4C,Y

F703-

F6

B5

INC

*B5,X

F7>

35-

80

BRK

¥?\

S&-

rv. t

88

STA

$88

F7i

38-

§5

81

LDA

$81 , X

F7i

3h-

85

01

STA

tM

F7i

ik-

f.d

RTS

F7i

3D-

A5

08

LDA

±00

F7@F-

95

00

STA

400 ■ «

F711-

A5

81

LDA

$01

F713-

qs

81

STA

$01, X

F715-

6 a

RTS

F71S-

A3

80

LDA

#$88

F718-

85

81

STA

$01

F71A-

85

ID

STA

$1D

F71C-

Hi

00

LDA

(.$&&,%)

F71E-

85

00

STA

$00

F728-

F6

80

INC

$88,X

F722-

D8

02

BNE

$F726

w~

F6

81

INC

$81, X

Photo 4: Far from being limited to interpretive integer BASIC, the Apple-ll includes some powerful debugging and softwaredevelopment aids at the machine language level. Here at (a) is an example of its dissassembler mode of operation, invoked by theL command following an address in hexadecimal. A corresponding nonsymbolic assembler program will perform transformationsin the other direction from text sources. Here at (b) is an example of the instruction trace command, which allows a machinelanguage program to be followed mnemonically via dynamic disassembly, with register and condition code contents indicatedafter each instruction.

input routine then enters a loop whichcounts the length of the timer output pulse,which is a function of the paddle potentiom-eter's setting. To prevent endless loops if awire breaks, the paddle scan routines exit atthe maximum count of 255. The resolutionof the loop is 12 ms per count.

One memory address is dedicated to theaudio output port which drives a speaker.When this memory location is referencedfrom a program, with either a read or a writeoperation, the speaker drive line is toggled.Generating tones requires continuousspeaker toggling by this method, at anaudible rate. The cassette output port worksin a similar (toggle) fashion to generateaudio tones for the tape. The annunciatoroutputs each have two corresponding ad-dresses, with one used to set the output andthe second used to clear the outputs. Switch,paddle and cassette inputs place their dataon the system bus in the sign bit positionwhen their corresponding addresses are refer-enced; this choice of wiring enables softwareto test the state of the bit directly with aconditional branch instruction of the 6502processor.

Apple BASIC

Apple-ll comes with an Apple BASICinterpreter in the mask programmed readonly memories of the system. There is noneed to load it off tape, nor to dedicate any

programmable memory for it. It's alwaysthere and it is impossible to accidentallyclobber it. This BASIC is essentially similarto any BASIC with the exceptions that itonly implements 16 bit fixed point arithme-tic. It also features some unique languageextensions to take advantage of the Apple-llhardware features such as color graphics andto provide conveniences in the form ofdebugging aids. It is intended primarily forgames and educational uses.

A monitor command puts you intoBASIC mode, which is indicated on thescreen by a prompt character, " >".Memory limits for BASIC source programsand data are set automatically at the time ofentry, but these limits may be varied by usercommands. While in BASIC mode, state-ments are entered on the current systeminput device, which is normally the key-board.

Apple-ll BASIC is implemented as atranslator-interpreter combination. When aline is read from the input device, thetranslator analyzes it and generates a moreefficient internal language facsimile. Syntaxerrors are detected at this time. The "nouns"of this internal language are variable names,integer constants (preconverted to binary forexecution speed enhancement), and stringconstants. The "verbs" are 1 byte tokenssubstituted for keywords, operators anddelimiters. Because the translator dis-tinguishes syntax, different verbs are as-

41

ONE SECTION, 553 QUAD TIMER

FROM I BITOUTPUT PORT "

ONESHOT

TRIGGER OUT

CONTROL

m

Lv

_T0 I BIT"INPUT PORT

USER SUPPLIEDVARIABLE RESISTANCE

o-

-y&r-

REAL WORLD

<D!C^

Figure 2: How to make a I bit measurement of an analog parameter forgames (or perhaps we should say "2bit"). Basically, a 555 style timingelement is set up so that it can be triggered by a i bit output port. Aftertriggering the oneshot, the processor enters a timing loop continuously testingthe I bit input port until the end of the oneshot's cycle, which is controlledby the game parameter potentiometer. The result is an integer countdeveloped by the timing loop which gives a measure of how long the oneshotpulse lasted, and hence a measure of the position of the input potentiometer.Apple-// implements four of these resistance measuring ports (which haveplenty of accuracy for game contexts with graphics display feedback but arehardly not to be interpreted as having any absolute accuracy independent ofhand-eye coordination).

signed to different usages of the samesymbol. For example, three distinct verbsrepresent the word PRINT, depending onwhether it is immediately followed by astring source, an arithmetic expression ornothing. Thus this distinction need not bemade at execution time. For each verb thereexists a subroutine to perform that specificaction. Listing a program actually involvesdecompiling the internal language back toBASIC source code. Those statements withline numbers are stored as part of the userprogram, while those without line numbersare executed immediately. If desired, theApple BASIC interpreter's editing functionscan be set to generate line numbers auto-matically. Although some commands arevalid only for immediate execution andothers only for programmed execution, mostcan be employed in both ways. In theBASIC source programs, multiple statementsmay reside on the same line, separated bycolons (':').

BASIC language statements are stored inuser memory as they are accepted andvariables are allocated space the first timethey are encountered during immediate orprogrammed execution. When a programterminates, whether by completion, inter-ruption or error conditions, all variables arepreserved. Programs may be interrupted inexecution by typing an ASCII control C; it isthen possible to examine and modify a few

Author's Note

So as not to slight theirefforts, I would like tothank Allen Baum fororiginating the Apple-//debug software, DougKraul for helpful sugges-tions on the 10 structure,and Randy Wigginton andChris Espinosa for manylong and late hours testingthe Apple BASIC. . .. SW

variables in immediate mode, then continueexecution at the point of interruption bytyping the CONtinue command. BASIC pro-vides the line number of the statement as thepoint of interruption when this sequence isused. The entire variable space is cleared tozero when BASIC is initialized by the CLRcommand, and prior to executing the RUNcommand. (It is possible to carry variablesfrom one program to another, but to initiatethe second program a GOTO command mustbe used instead of RUN in order to overridethe automatic clear at the beginning ofexecution of a new program.)

The interpreter consists of a standardexpression evaluator and a symbol tableroutine for allocating variable storage similarto those described by Prof Maurer in his 2part series in the February and March 1976issues of BYTE. As statements are scanned,nouns and verbs are encountered. Variablenames result in calls to the symbol tableroutine which pushes address and lengthinformation on the noun stack (operandstack). Constants are pushed directly ontothis stack. Verbs are pushed onto the verbstack (operator stack) after popping andexecuting any verbs of greater priority. Averb is executed by cailing its associatedsubroutine. Tables define priorities and rou-tine entry addresses for all verbs. Keywordssuch as THEN or STEP, and delimiters suchas commas and parentheses, are dealt withjust as though they were arithmetic opera-tors. Verb routines obtain their argumentsfrom the noun stack. Because verbs such asparentheses tend sometimes to be of low,and other times of high priority, each verb isactually assigned two priorities (left hand-right hand). One represents its tendency toforce execution of other verbs, the secondits tendency to be executed.

Interactive Monitor

The entry into BASIC, as well as otheruser oriented features of the Apple-ll, isprovided by an interactive keyboard monitorwhich serves as an aid to writing anddebugging machine language programs forthe 6502 processor of the system. The userenters commands from the keyboard speci-fying data and address parameters in hexa-decimal. Multiple commands are permittedon the same line and editing features facili-tate error correction. I completely wrote anddebugged Apple BASIC using the monitor asmy only software development tool. It wasof course the first hand assembled program Iwrote for the system. In addition to thedirect monitor commands, a number ofsubroutines were included in the Apple-ll'smask programmed system read only memory

42

Sweet Sixteen Calling Sequence:

20 89 F6

JSRSWEET16

(leave 6502direct execution)

SWEET 16OP CODES

6502

SWEET16 CODE

RETURN

OP CODE

(reenter direct

6502 execution)

SWEET16 OP CODES (16 Bit Operands, 2's Complement Arithmetic)

Op

Instr

Op

Code

Length

Description

Code Length

00

1

Return to 6502 mode

_

01

2

Branch always

1R 3

02

2

Branch no carry

2R 1

03

2

Branch on carry

3R 1

04

2

Branch on positive

4R 1

05

2

Branch on negative

5R 1

06

2

Branch if equal

6R 1

07

2

Branch not equal

7R 1

08

2

Branch on negative 1

8R 1

09

2

Branch not negative 1

9R 1

0A

1

Break to monitor

AR 1

0B

1

No operation

BR 1

0C

1

No operation

CR 1

0D

1

No operation

DR 1

0E

1

No operation

ER 1

OF

1

No operation

FR 1

Description

R^2 byte constant (Load register immediate)

ACC-R

ACC-R

ACC-@R, R<-R+1

ACC->@R, R-R + 1

ACC<-@R double

ACC-'@R double

R<-R-1, ACC<-@R (pop)

R*-R-1, ACC-*@R

ACCM3R (pop) double

COMPARE ACC to R

ACC-ACC+R

ACC<-ACC-R

R^-R + 1

R<-R—1

Notes.

1. All branches are followed by a 1 byte relative displacement. Works identically to6502 branches.

2. Only ADD, SUB and COMPARE can set carry.

3. Notation:

R = a 16 bit "register" operand designation, one of 16 labelled 0 to 15

(decimal), 0 to F (hexadecimal).ACC = register operand R0.@R = indirect reference, using the register R as the pointer.

_ f <" assignment of values.

4. Length of instructions:

Branches are always two bytes: op code followed by relative displacement.Load register immediate (1R) is three bytes: the hexadecimal op code 10

to 1 F followed by the 2 byte literal value of a 16 bit number.All other instructions are one byte in length.

The Apple-11 monitor readonly memory also containsan interpreter programcalled SWEET/6 whichcan be used from machinelanguage programs to im-plement 16 bit arithmeticoperations. This facilitycan prove quite useful, forexample, in calculating ad-dresses, and serves as anextension of the instruc-tion set of the 6502 whichis reached by the JSRS WEETI6 escape sequencein code.

to provide easy access to hardware features.These arc the service routines which are usedby the monitor, as well as BASIC and anyuser routines you care to code.

The Story of Sweet Sixteen

While writing Apple BASIC, I ran into theproblem of manipulating the 16 bit pointerdata and its arithmetic in an 8 bit machine.

My solution to this problem of handling16 bit data, notably pointers, with an 8 bitmicroprocessor was to implement a non-existent 16 bit processor in software, inter-preter fashion, which I refer to asSWEET16.

SWEET! 6 contains sixteen internal 16 bitregisters, actually the first 32 bytes in mainmemory, labelled R0 through R15. R0 isdefined as the accumulator, RI5 as theprogram counter, and R14 as a status reg-ister. R13 stores the result of all COM-PARE operations for branch testing. The

user accesses SWEET16 with a subroutinecall to hexadecimal address F689. Bytesstored after the subroutine call are thereafterinterpreted and executed by SWEET16. Oneof SWEET16's commands returns the userback to 6502 mode, even restoring theoriginal register contents.

Implemented in only 300 bytes of code,SWEET16 has a very simple instruction settailored to operations such as memorymoves and stack manipulation. Most opcodes are only one byte long, but since sheruns approximately ten times slower thanequivalent 6502 code, SWEET16 should beemployed only when code is at a premiumor execution speed is not. As an example ofher usefulness, I have estimated that aboutI K bytes could be weeded out of my 5 Kbyte Apple-ll BASIC interpreter with noobservable performance degradation byselectively applying SWEET16."

43

Continued from page 32

Current

State

input Observation

A

B

C

output:

output:

output:

response A

response B

response C

R

new current

new current

new current

state: R

state: R

state: R

output:

output:

output:

response A

response B

response C

S

new current

new current

new current

state: S

state: S

state: S

output:

output:

output:

response A

response B

response C

T

new current

new current

new current

state: T

state: T

state: T

Figure 2: State spacemodel in matrix represen-tation. The model can bedescribed by an n by mmatrix. The number ofstates in the model is nand the number of inputtypes is m. Each elementdescribes the output re-sponse and the new cur-rent state to which thenext move is made.

current state = S

Byte

0,12,3

(n-1) *2,(n-1) *2+1

Use

State 1State 2

State n

now complete in the definition of themutation types desired in our evolutionsimulation.

The State Space Model

and Its Computer Representation

We now have sufficient knowledge tobegin examining the computer implementa-tion of this artificial intelligence by simu-lated evolution. Although the discussion willtend to be general, the emphasis is on usingthe technique as a two symbol patternrecognition game. This game would thenallow the computer programmer to experi-ment on his/her own system with predictingprimes, earthquakes, people or any of thevirtually limitless areas of pattern recogni-tion and feature extraction. Those program-mers with a more extensive background inmathematics and automata theory and withlarger computer facilities at their disposalmay want to attempt more sophisticatedprograms with many symbol pattern recogni-tion, advanced evolutionary techniques, oreven using the intelligence of the program toimprove upon the intelligence process.

The most important design decision for

Bit Use

0 Output response type:on is response type 1off is response type 0

1—7 New current state.

Table I: The representation that is used in the computer model for the 2symbol pattern recognition. Table la is the memory al local ion for the matrix.Each state has two bytes with which to work. Each byte is broken into twosections as shown in table lb. Bit I is used to signify the output responsetype, either response 0 or I. The remaining seven bits are used to indicate thenew current state.

the program is the representation method ofthe model. Figure 2 shows that the modelcan be represented as an n by m matrixwhere n is the number of states in the modeland m is the number of input types. Eachclement on the matrix consists of two piecesof information, a symbol to output and thenext current state. Thus, if the model iscurrently at state S and input symbol type Boccurs, then row S and column B of thematrix defines the output response and thenext current state.

Al least five other pieces of informationmust also be maintained for the model,namely the first state, second state, thecurrent state, value and the number of statescurrently in the model. The current state isused to derive the model's next response.The first state, second state and value areused by the evolution process when themodel must be driven by historical data, aswhen determining which of the offspringduring mutation is the best. The number ofstates currently in the machine is also usedby the mutation or evolution routines, aswill be seen later.

Table I details a workable representationof a two symbol pattern recognition modelfor a small computer. Each clement in the nby m matrix consists of two bytes. One bytefor each possible transition. For both bytes,the high order bit determines the outputsymbol. For example, high order bit oncould mean "next number is prime," or "anearthquake will occur next," or "the op-ponent will next say true." High order bitoff would of course mean the opposite. Theother seven bits in the byte contain therelative number of the next current state,state numbers ranging from 0 to 127. De-coding the model to make a prediction is

44

FRANKLIN ELECTRIC Co.

altair - IMSAI - S-100 BUSPLUG COMPATIBLE

Check these features ...

ACCESS TIME - 450ns No wait states

FULLY BUFFERED - for BUS reliability

LOW POWER CHIPS - for long life and low power drain

MEMORY WRITE PROTECT - Hardware, 2K segments

POWER REGULATION - 4 Regulators for reliability

ADDRESS SELECT-1K boundaries- Dip. Switch

LED MEMORY SELECT INDICATOR - Visual Check

LED MEMORY PROTECT INDICATOR - Visual Check

BATTERY BACKUP PROVISION - Saves memory during power failure

OUTPUT DISABLE — Switch selectable for transparent loader application

P.C. BOARD — Quality G10 material with solder mask both sides and silkscreen

SOFTWARE - Diagnostic provided

To Order

Price

NameCny _

AddressState

_Zip

Enclosed is S

Check □ Money Order □

KIT - With IC Sockets S239

KIT - Without Sockets S225

Solder chips directly to PCB

ASSEMBLED - With Sockets S295

ASSEMBLED - Without Sockets S280

Bill my BankAmencard □: Master Charge □: Card No.

Exp. Date Interbank No.

Signature

Handling and Postage S2.50. California Residents add 6% sales tax.

FE

FRANKLIN ELECTRIC Co.

733 LAKEFIELD ROAD

WESTLAKE VILLAGE. CA 91361

(805) 497-7755 A

easily done on most microprocessors and atypical sequence of instructions would be:

into

5a

Load current state numberaccumulator.

Shift left one place (equivalent tomultiplying by 2).Add input symbol type (a 0 or a 1).The result of step 3 is the relativenumber from the beginning of themodel of the byte representing thetransition to be taken. Load thisrelative byte into the accumulator.If high order bit is on, then theresponse (prediction) is type 1.

5b. If high order bit is off, then theresponse is type 0.

6. "AND" accumulator with hexadeci-mal 7F; the result is the new cur-rent state.

Part 1 of this article has described thegeneral overall workings of the simulatedevolution technique. Using the knowledgethus far presented, the reader is prepared towrite his/her own artificial intelligence pro-gram for predicting earthquakes, primes oreven people. Next month this discussionwill continue with a description of the im-plementation of a predictive game withwhich the readers can experiment."

The

®.

fabulous Phi-Deck familyof 5 cassette transports

UnCl©r$1UU in quantities of 10

Featuring:

• Die-cast frames

• Remote controllable

• Precise, fast headengage/disengage

• Quick braking

• FF/rewind 120 ips

• Speed ranges from.4 to 20 ips

Electronic packages and mag heads for most applicationsFor application in:

1.

Micro processing

7.

Security/automatic warning

2.

Data

systems

recording/logging/storage

8.

Test applications

3.

Programming

9.

Audio visual/education

4.

Instrumentation

10.

Telephone interconnect

5.

Industrial Control

11.

Hi-Fi

6.

RS232 Data storage

12.

Point of sale

aTHplel A Division of the Economy Co. bA4605 N. Stiles P.O. Box 25308J Oklahoma City, Oklahoma 73125 (405) 521-9000

□ I am interested in application no

□ Have Representative call □ Send application notes

Name

Company Name.

Address

City.

.Title

. State.

Phone Number.

Zip.

45

Whafs

A New Low for Paper Tape Reader Prices

Personal use review byDaniel FylstraHamilton Hall C 23Harvard Business SchoolBoston MA 02163

Now you can add a paper tape readerto your personal computer for only$32,50. The new RAECO TPR-1 is a"pull through" type optical paper tapereader using normal ambient light and nomoving parts. A machined tape guidemakes it relatively easy to pull tapesmoothly through the unit. Although thereader works best with opaque (black)paper tape, it can be used with a littlecare to read the buff-colored tape

designed for mechanical readers. Theunit is easily interfaced to any processorthrough an 8 bit parallel IO port, with aREADY (or READY ) signal to indicatethe presence of valid data. Since the unithas three-state output buffers controlledby a separate ENABLE line, it theoreti-cally could be connected directly to adata bus.

The TPR-1 was below my pricethreshold for a paper tape capability, soI ordered one for use with my KIM-1.RAECO gave me unusually promptservice, less than one week, during thebusy Christmas season. Instructionssupplied with the TPR-1 were clear andcomplete, and in less than two hours Ihad connected the unit to my system.After carefully positioning the desk lampI was using as a light source, I subjectedthe TPR-1 to the paper tape reader "acidtest," loading Tom Pittman's TinyBASIC, a fairly lengthy program, from abuff-colored, fan-folded paper tape. Sureenough, I was able to load the programwith only one retry after a checksumerror.

RAECO has done an excellent job ofbringing a paper tape reader capability tothe personal computing user at a newlow price. The RAECO TPR-1, as-sembled and tested, $32.50 (optionalcase, as pictured, $5 extra), fromRAECO, Box 14, Readville MA 02137."

nun

-%S;B Series

■£l*9"al logic

RCA Has Just Published a New ProductGuide to Its CMOS-B Series ofIntegrated Circuits

A 24 page product guide, COS-278F,COS/MOS-B Series, The new standard inCMOS digital logic, is now available fromRCA Solid State Division. The bookletdescribes RCA's B series of COS/MOShigh-voltage integrated circuits. All Bseries devices are tested to voltages ashigh as 22 V and have an absolutemaximum DC supply voltage rating of20 V. The comparable rating for thetraditional A series is 15 V.

The product guide contains a descrip-tion of the features and benefits of the Bseries, function classification chart, func-tion selection chart, standardized staticelectrical characteristics, and functiondiagrams for 120 B series types, includ-ing buffered and unbuffered versions.Special information on seven standardtiming circuits is also included. Copies ofthe COS-278F may be obtained bywriting to RCA Solid State Division,POB 3200, Somerville Nj 08876.-

Zilog'sZ-80Aat4 MHz

At its new manufacturing facility inCupertino CA, Zilog announced themanufacture of the Z-80A microproces-sor on February 24 1977. The Z-80A isa faster microprocessor than the Z-80and is pin and software compatible withthe Z-80. The Z-80A has a standardclock rate of 4 MHz which is madepossible by a new technology developedby Zilog. Single quantity prices quotedat the press conference were $65 for theceramic package, and $59 for the plasticpackage. The Z-80A will become Zilog'sstandard microprocessor. However, thepresent Z-80 at a clock rate of 2.5 MHzwill be continued at a reduced price.

According to Zilog, the Z-80A isconsidered to be the fastest standardmicroprocessor. Its instruction cycle is 1US, and its throughput is 60% above thethroughput of the Z-80. It becameavailable in production quantities in lateMarch, 1977. For more informationwrite to Zilog, 10460 Bubb Rd,Cupertino CA 95014, (408) 446-4666."

Want Megabyte Megalomania?

Here is an inexpensive way to achievea 32 megabyte mass storage system foruse in filing lots of data. The product isthe Model 5200 Carousel tape cartridgesystem by National Computer Systems,4401 W 76th St, Minneapolis MN 55435.What does inexpensive mean? In thiscontext, it means that $3215 (in quan-tities of 50) purchases you a singleCarousel engineered for use with mini-computers or microcomputers, using abuilt-in dual microprocessor formatterwhich provides interfacing disciplines,handles housekeeping functions for thestorage device, and reduces the usercomputer's driving software require-ments to command information and datatransfer.

This machine is designed for unat-tended operation. All the mechanicaloperations of indexing the cartridge posi-tions, loading, processing data and un-loading are done automatically. Thismeans that data can be copied, filessorted, information updated and reports

46

INTRODUCING THE COMPLETECHALLENGER SYSTEM.

a

OSI's DREAM MACHINEis a totally integrated computer system.

Imagine a system complete with terminal, CPU, memory,floppy disk, software, and all the little necessities to make itwork together immediately. Now imagine this complete systemavailable not only fully assembled, but priced much lower thananyone else's kit. What you are dreaming of is OSI's "new"Challenger System!

In the configuration shown above, the Challenger includeseverything an end user needs for a complete small computersystem. All you add is 110 VAC power and a desk to put it on.

This fully-assembled system includes:

HARDWARE:

OSI Challenger 65 with 16K RAM, serial interface, systemmonitor PROM, and floppy disk bootstrap PROM.

OSI Challenger single drive floppy disk formatted for 250Kbytes storage per diskette surface.

Stand-alone terminal and Sanyo monitor for 16 lines of 64characters at 2400 baud (other terminal options are available).

And all interconnecting cables!

SOFTWARE:

2 diskettes containing over 100,000 bytes of software in-cluding OSI's powerful Disk Operating System with variablelength sectors. 6502 DISK BASED RESIDENT ASSEMBLER/EDITOR! A totally interactive Assembler/Editor which as-sembles up to 600 lines a minute and is completely compatiblewith MOS Technology's Cross Assembler format. This programalso contains a powerful disk-based line editor with commandsfor general text editing. OSI'S EXTENDED MONITOR: A power-ful machine language debugging and utilities package includinga Disassembler which is format compatible with the Assembler!OSI 6502 8K BASIC FOR DISK BY MICROSOFT: This powerfulBASIC has all the features of Altair™ 8K BASIC for the 8080plus higher speed and disk storage. And it comes completewith a BASIC program library.

DOCUMENTATION AND SUPPORT:

We include over 600 pages of hardware, software, program-ming, and operation manuals. The Challenger is based on thewell-proven OSI 400 system. The over 2,000 OSI 400s andChallengers now in use assure continuing hardware and soft-ware support for this system for years to come!

EXPANDABILITY:

The Challenger System can now be expanded to 192K ofRAM and 16K of I/O and ROM. There are over 13 accessoryboards including A/D, D/A, parallel and serial I/O, cassetteinterfaces, a dual drive floppy, a video graphics display, severalRAM and PROM boards, and multiple-processor configurations.

APPLICATIONS:

The Challenger system is complete, fully assembled andconfigured so that the Disk Operating System can be bootedin immediately on system power-up. Even a relatively inex-perienced operator can have a complex BASIC program on-linejust seconds after the system is turned on. The ease of use,high reliability, and large library of standard BASIC applica-tions programs make the OSI Challenger System the firstpractical and affordable small computer system for smallbusiness, educational institutions, labs, and the personalcomputerist.

PRICES:

Challenger System, complete as stated above with terminaland monitor

$2599°°

As above without terminal. Specify RS-232 or 20ma loopand baud rate $209900

IMPORTANT NOTE:

One of the most important features of the Challenger Systemis that it is not really "new". OSI has been delivering the basiccircuitry of the Challenger since November 1975 and the floppydisk since June 1976. The only thing new is the total integrationof the components as a complete, simple to use, fully-assem-bled, small computer system.

For more free information and the address of the OSIComputer Dealer or representative in your area, write to:OSI; Dept. S; Hiram, Ohio 44234 or enclose $1.00 for the fullOSI catalog which contains kits from $134 and fully assembledcomputers from $439.

I

Ohio Scientific Instruments

11679 Hayden Street, Dept. S, Hiram, Ohio 44234

spooled without operator intervention.Put this device together with an LSI-11,DEC'S timesharing operating systems,multiple terminal ports, and a school orbusiness will have a very inexpensivedata processing system with lots ofusable mass storage. Usable in this casemeans 8000 bytes per second data trans-fer rate to the 3M style cartridges, searchspeed of 120 inches per second (3.1meters per second) and rewind speed of180 inches per second (4.6 meters persecond). This translates (assuming a 300foot (91 meter) 3M cartridge tape capac-ity) into a maximum access time of 20seconds for any given cartridge, assumingthat you are at the last block on thatcartridge and you have to rewind to getto the first block. Indexing from car-tridge to cartridge takes 4.25 seconds, somaking the assumption that we canindex in either direction, the worst caseaccess time to a given block would be:

Rewind from last block, present cartricStep eight times 4.25 x 8 =Search forward to last block, new cartr

disks and the whole works. The singlequantity price of this Carousel drive willmost likely fit within the "conceivable"personal computing budget of the highlevel management person such as thisfellow (or owner of a small business withpotential commercial applications).

But more important, to those of uswho have far more limited budgets, isthe inspiration provided by this conceptof the multiple cartridge mechanism.Why not do the same thing with Philipscassettes for less money, perhaps withfewer units of the media? Or evenconsider a simpler mechanism with fewercartridges used by the personal computerexperimenter on a lower budget? Justthe very concept of a 3M drive with the1/4 inch tape cartridges is enough toexcite the personal user, since it providesthe potential for 2 million bytes percartridge, electronically controllablewith fast access to any block."

idge

Does This Have Any Relevanceto the Individual?

Yes and no. Yes, in the fact that forsome individuals, the price is well withinbudget. We all know of people who havefull fledged minicomputer systems astheir personal computers. One exampleis a data processing vice president of alarge East Coast bank who has aPDP-11/40 in his home with hard surface

20 seconds (1 80 ips, 300 feet)

34 seconds

30 seconds (1 20 ips, 300 feet)

84 seconds

Expansion of Capacity

Latest word from Texas Instrumentsin Dallas is announcement of an increasein the programmable memory and datacapacity of the SR-60 desk top calcu-lator. This machine is now available withup to 5760 steps of programming with430 data registers — almost enough

capacity to wonder whether or not it isreally a calculator as opposed to a fullfledged computer. For all that capacityin the new form, you'll pay a bithowever: $3,31 5 is the total price for anSR-60 equipped with that many programsteps and data registers. Texas Instru-ments calculator products are availablefrom many department stores and simi-lar retail outlets, or you can forwardinquiries to Texas Instruments Inc, In-quiry Answering Service, POB 5012,MS 308, Dallas TX 75222, attention:SR-60 Memory Addition."

TARGET

Altair Program Library entry#5-3-764 is a game called TARGET byGeorge W Rompot, which uses the Proc-essor Technology VDM-1 video displaymonitor to play a simulated shootinggallery operation with a "gunship,""missile" and "target" moving about thescreen. The program is written in 8080machine code. The target moves at 5lines per second up and down the rightedge of the machine, and the missilemoves across the center of the screen at120 character positions per second; themissile is fired in response to a keyboardinput of any character. The skill requiredis represented by the need to "lead" thetarget. The MITS game comes in theform of 9 pages of documentation in-cluding 5 pages of commented programlisting in octal for this 197 byte programand a 13 byte screen initializationroutine."

Let's talk about a Real Bargain

It's the Typewriter/Terminal from AJ

We have hundreds of ready-for-lease, or

ready-for-sale terminals that have

been refurbished and repriced

to make them a truly

outstanding

bargain.

Use it as a typewriter!

Our AJ 841 features the heavy duty Selectric IBM mechanism to give

you fast, dependable operation day after day. Use it in the office. Use

it at home. At our price, it's an economical typewriter.

Use it as a terminal!

The 841 incorporates our own SELECTRONICmechanism that turns it into one of the most usefuland reliable computer terminals on the market.Thousands are in operation today. Your choiceof EBCD or Correspondence Codes, with APLas an option. It will interface with almostany IBM computer.If you can use an efficient, low costcomputer terminal, here's your chanceto get one for about the price of a goodtypewriter alone.

If you're interested, call AJ Marketingat 408-263-8520, Extension 280,or write for more details.

ANDERSON

521 Charcot Avenue ■ San Jose, CA 95131 • (408) 263-8520

EASTERN REGION/Hackensack. N.J. (201) 488-2525 ■ CENTRAL REGION/Northbrook (Chicago). 111. (312) 498-4220

IMSAI Presents:

The 3 fori Slot Saver

A Masterpiece in I/O Engineering.

Save

money and ex-pand your computer.The IMSAI Multiple Input/Output board contains five ports •combining the most commonly used I/Ointerfaces. This compact, sophisticated boardreplaces two or three older-type boards at lower costwhile making more slots available for new applica-tions. The IMSAI MIO, like the IMSAI 8080. dem-onstrates that fine engineering can be aestheticallybeautiful as well as solidly practical.

USEFUL AND EASY TO USE.

The IMSAI MIO is inexpensive and easy to install. It'sthe most advanced I/O board available, adding qual-ity, convenience and value to your computer. With theIMSAI MIO you can control a keyboard, printer, 2tape cassettes and a teletype/CRT simultaneously.

Consider these important "useability" features:

1. Easy to assemble components — all boardidentities are silk-screened.

2. Safe soldering — the entire board is soldermasked for quick, fast assembly.

3. Fast, flexible configuration — options areselected with solderless wire strapping.

4. Easy testing and tuning—pre-recorded testroutines on tape cassette.

5. Best of all — everything is explained incomprehensive, understandable documen-tation.

TOTAL FLEXIBILITY

A control port, serial channel, 2 parallel I/O ports anda two-tape cassette interface provide all the versatilityyou need in an I/O board. The IMSAI MIO's flexibleaddressing and control features assure compatibilitywith non-IMSAI 8080 software. Tape cassette applica-tions are enhanced through inclusion of the Byte/Lancaster and Tarbell recording modes.

ORDER NOW—SHIPPING NOW

The IMSAI MIO is available for immediate delivery.$195 in kit; $350 assembled. Write or call for more in-formation. Specifications and feature product bulletinavailable on request. Send $1 for complete catalog ofIMSAI products.

Prices: USA Domestic. Subject to change without notice.

IMSAI

IMSAI Manufacturing Corporation

14860 Wicks Blvd.San Leandro, CA 94577(415)483-2093TWX 910 366-7287

Come Upstairs

PAofo 7: 7?;e Remote Re-ceiver Assembly. This isonly one of the circuitlayouts possible. Place-ment of parts is notcrucial. The receiver isbuilt so that it can beplugged directly into themicroprocessor's mainboard.

Photo 2: The Remote Transmitter Assembly. The transmitter also needs apower supply, contained within this box, for both itself and the keyboard.With a stylish cabinet such as this, you can be proud to display your newestaddition to your friends.

Steve Ciarcia

POB 582

Glastonbury CT 06033

For those of you who remember aboutWalt and Ralph in "Having a Private AffairWith Your Computer" [April 1977 issue ofBYTE], I suppose I can say that with friendslike that I am not in any great need ofenemies. What may have appeared as a losingsituation on my part did have some benefi-cial side effects — namely, the remote ter-minal which I installed in my den to accom-modate the comings and goings of peopleusing my system.

This remote terminal is nothing morethan a serial data link incorporating a univer-sal asynchronous receiver-transmitter(UART) attached to a keyboard and acoaxial extension cable for a direct plug-inmonitor. Any computer system which canbe directly operated by a keyboard can beconverted for remote input exactly as I willdescribe. The components are readily avail-able and total cost should be less than $30.

The major application for a remote inter-face is to be able to describe and demon-strate your computer without having toclean up your shop before letting people inor worrying about what they'll touch. Often,when I have large parties, I will put aKingdom game on the computer and letpeople play to their hearts' content in theden. Obviously, trying to do this in thebasement where the computer is locatedwould require constant attendance. All itwould take is one drunk to lean on theprocessor card, or say, "What does this do?",as he flips the memory clear switch. I willhave to admit though that what had origi-nally started as a purely defensively initiateddesign has become an enjoyable addition tomy system. If just writing software, I'll do itupstairs now, with the family, rather thanappearing to isolate myself in the cellarevery night, getting moldy, as my wife says.

A simplified block diagram of this remoteterminal link is illustrated in figure 1. Forthe keyboard inputs to the computer bothtransmitter and receiver interfaces utilize aninteresting device called a universal asyn-

50

and Be Respectable

chronous receiver-transmitter. The internalstructure of this device consists of a separateparallel to serial transmitter and serial toparallel receiver joined by common program-ming pins. What this means, in fact, is that thetwo sections can be used independentlyprovided they adhere to the same bit formatwhich is selectable through the wiring of thedevice.

The transmission from the den to thebasement is done asynchronously and in onedirection only. As far as the computer isconcerned, this input device appears as anyother parallel input such as a keyboard. Theother part of the system is a monitor todisplay computer generated video. Themonitor in the den uses direct video signalsand is attached to the video display elec-tronics through a 200 foot coaxial cable, andthus does not require the computer to re-spond via the serial line.

Actual data transmission to the computerfollows an asynchronous serial format illus-trated in figure 2. When no data is being

transmitted, the data line is sitting at a markor 1 level waiting for a key pressed strobefrom the keyboard. A key pressed strobe is a1 to 5 ms positive pulse indicating that akeyboard key has been pressed and that anASCII code of that key is available fortransmission. This key pressed strobe, whichis attached to the data strobe of the inter-face, causes the ASCII data to be loaded intoa parallel storage buffer, and starts thetransmission cycle. The serial output willthen make a transition from a logical 1 to 0.This start bit transition indicates the begin-ning of a serially transmitted word. Fol-lowing the start bit, up to eight bits of datafollow, each data bit taking 16 clockperiods. At the conclusion of the data bits,parity and stop bits are generated by theinterface to signify the end of transmission.If another key is pressed, the process willrepeat itself. On the receiving end, thereceiver section of the UART is con-tinuously monitoring the serial input linesfor the start bit. Upon its occurrence the

-TWISTED PAIR CABLE-

Figure 1: A simplifiedblock diagram of the re-mote transmitter and re-ceiver circuit. With a1760 Hz oscillator drivingthe circuit, a datatransmission rate of110 bps will be attained.Although the exact fre-quency is not important,the two oscillators must beaccurate in respect to eachother or the circuit willnot function correctly.

+ 5V

KEY PRESSED

BOBl82B3B4B5B6

KEYBOARD

J"L

+ 5V

L

+5V

-I2V

LINEDRIVER

5VL_f

-*f

LINERECEIVER

SERIAL DATA

_ SO

DS

BDI

B02

BD3

BD4

BD5

BD6

BD7

-I2vl_?

INTERFACE

INTERFACE

5VSERIAL DATA

RDAVRD7RD6RD5RD4RD3RD2ROIRCP

+5V

1760HzOSCILLATOR

•12V

l3v

LOCAL POWERSUPPLY

^V

1760 HzOSCILLATOR

f >

LOCAL

VIDEO

MONITOR

COAXIAL

-# — —>

o o o

CABLE

+5V

-I2V

COMPUTERPOWERSUPPLY

87B685B4B3B2BlBO

/MICROPROCESSOR

8 BIT PARALLELINPUT PORT

t

VIDEO

DISPLAY

GENERATOR

-MICROPROCESSOR

51

Figure 2: Diagram illustrat-ing how asynchronousdata is transmitted, A startbit is defined as a transi-tion from logical I to 0.The eight data bits arethen transmitted with theleast significant bit beingtransmitted first and themost significant bit beingtransmitted last. A paritybit is then sent followedby two stop bits. With theAY-5-1013, the parity bitcan be omitted completelyand there is a choice ofone or two stop bits fol-lowing the transmitteddata.

START DATA I DATA2DATA3 DATA4DATA5 DATA 6 DATA7DATA8 PARITY STOP I STOP2 START DATA I| I I I 1 | I l I I

!LS B

,MSB

_l_

TIME'S ARROW

eight bits of data are slipped into a registerand the parity checked. At the completionof the serial entry, an output signifying dataavailable is set which can be used as an inputstrobe to the computer. The interface willnot process additional serial inputs unlessthe data available flag is acknowledged andthe data available reset line is strobed.Actual transmission can include or excludeparity, have one or two stop bits, and datacan be in 5 to 8 bit words. These options arepin selectable.

Table 1 is a pin function description forthe AY-5-1013.

There are obviously many more function-al inputs and outputs than are necessary forthis limited application. We will purposelyselect only those which are absolutely neces-sary to minimize hardware and softwarelogic. The keyboard has a 7 bit ASCIIoutput code so a 7 bit word length is chosenby a binary 10 code on pins 37 and 38respectively. Two stop bits provide for amore reliable transmission by allowing moretime between transmitted words. Two stopbits arc selected by tying pin 36 to +5 V.Parity is nice, but unless you arc going to dosomething about it, it's a waste of time. At

A

>33K

i'lOK

IOK

-Wv—

T7^1 * I

lO^F

RESET VCCDISCHAR6E

IC3NE555 OUTPUT

THRESHOLD

TRIGGER GND

I

^v

..OUF*

* MYLAR OR

POLYCARBONATE

Figure 3: A schematic dia-gram of the receiver inter-face for the remote key-board. This section can bebuilt on a vector card andinstalled in the computer'smainframe. All resistorsare 714 W and all resis-tances are measured inohms.

£

ICI

ROI

DATA

AVAILABLE

AY-5-1013

110 bps, failures will be rare and in manyhours of operation I have not yet received abad character transmission. Parity iseliminated by tying pin 35 to +5 V.

Both transmitter and receiver interfacesutilize an NE555 oscillator to provide theclock frequency (see figures 3 and 4 forschematics). For a 110 bps serial rate, thisfrequency is set for 1760 Hz and must bemaintained within 1%. For this reason onlymylar or polycarbonate capacitors should beused. This transmission rate can be muchhigher, possibly reaching a rate of 20 or 30thousand bits per second. But we must berealistic: 110 bps is 10 characters a second,which is beyond the typing capabilities ofmost sane individuals. Building a 9600 bitper second data link to a keyboard is absurd.The lower the data rate, the fewer problemsyou will encounter in the long run.

Construction of the receiver and transmit-ter boards is straightforward and wiring isnot critical. The unit in the den requires a+5 V and -12 V power supply and an ap-propriate case. Most new keyboards require+5 V for operation and the interface powersupply should be made large enough toaccommodate both.

All my keyboards have cables with 11 pin"octal type" sockets [electron tube socketsand plugs similar to those of the large

RESET

DATA

AVAILABLE

I-5V

C>B7 DATA READY

X

^lOOpF

DM8820 RECEIVER (SND5I82)

OUTPUT

STROBE

RESPONSE

IC2 RT

DM8820 ^ir.oi

t

FROM

j>oooooocx::; remote

SITE

52

"octal" tubes J, so I naturally used the samereceptacle on this transmitter box. The cableand connector can be any convenient type,and the keyboard will probably pull lessthan 200 mA. The only other connection isthe twisted pair wire to the receiver board

and this should be some easy disconnect likean RCA jack or two banana jacks, as I used.The receiver construction is equallysimplistic and its proximity to the computereliminates the necessity for building addi-tional power supplies. When a character is

Pin

Number

12345-12

16

17

36

37-38

Name

VCC power supplyVGG power supplyVDD power supplyReceived Data EnableReceived Data Bits

13 Parity Error

14 Framing Error1 5 Over Run

Status Word Enable

Receiver Clock

24 End of Character

25 Serial Output

26-33 Data Bit Inputs

34 Control Strobe

35 No parity

Number ofStop Bits

Number of bitsper character

39 Odd or even parity

select

Symbol

VCCVGGVDDRDERD8-RD1

PE

FEOR

SWE

RCP

18

Reset Data Available

RDAV

19

Data Available

DAV

20

Serial Input

SI

21

External Reset

XR

22

Transmitter Buffer

TBMT

Empty

23

Data Strobe

DS

EOC

SO

BD1-BD8CS

NP

TSBNB2.NB1

40

Transmitter Clock

EPS

TCP

Function

+5 V power supply.— 12 V power supply,ground.

logic 0 places the received data onto the output lines,eight data output lines. Received characters are rightjustified; the least significant bit always appears onRD1. These lines have three state drivers enabled bya low level on the RDE line.

goes to logic 1 if received character parity does notagree with selected parity. Three state output enabledby SWE.

goes to logic 1 if the received character has no validstop bit. Three state output enabled by SWE.goes to logic 1 if previously received character was notread before present character is transferred to receiverholding register. Three state output enabled by SWE.logic 0 on this line places status word bitsPE,FE,OR,DAV,TBMT onto the output lines. Threestate outputs.

contains clock whose frequency is 16 times the desiredreceiver data rate.

logic 0 will reset the data available line,goes to logic 1 when an entire character has been re-ceived and transferred to the receiver holding register.Three state output.

accepts the serial bit input stream. A logic 1 to logic 0transition is required for initiation of data reception,resets shift registers. Sets SO,EOC,TBMT to logic 1.Resets DAV and error flags to logic 0. Clears inputdata buffer. Tied to logic 0 when not in use.transmitter buffer empty flag goes to logic 1 whendata bits holding register may be loaded with anothercharacter. Three state output enabled by SWE.strobe on this line will enter data bits into the databits holding register. Initial data transmission is initi-ated by the rising edge of DS. Data must be stableduring entire strobe.

goes to logic 1 each time a full character is trans-mitted. It remains at this level until the start oftransmission of the next character.

serially, by bit, provides the entire transmitted charac-ter. It will remain at logic 1 when no data is beingtransmitted.

eight data bit input lines.

logic 1 enters the control bits EPS, NB1, NB2, TSB,NP into control bits holding register. Line can bestrobed or hard wired to logic 1 level,logic 1 will eliminate the parity bit from the trans-mitted and received character. Stop bits immediatelyfollow the last data bit. If not used, must be tied tologic 0.

selects the number of stop bits, 1 or 2, to be appendedimmediately after the parity bit. A logic 0 will insertone stop bit and a logic 1 will insert two stop bits,two leads internally decoded to select five, six, seven,eight data bits per character.

NB2 NB1 Bits per character0 0 5

0 1 6

1 0 71 1 8

determines type of parity appended immediately afterdata bits. Logic 0 inserts odd parity, logic 1 insertseven parity.

contains a clock whose frequency is 16 times thedesired transmitter data rate.

Table 1: A summary ofthe pins and functiondescription of theA Y-5-W13 universal asyn-chronous receiver andtransmitter.

53

■ 33K

IOK

IOK

5V6

1—rV" r

RESET VCCDISCHARGE

OUTPUTTHRESHOLDTRIGGER GND

I-5V

;.oimf*

rft

* MYLAR ORPOLYCARBONATE

X7

C7E555

IC5AY-5-IOI3

<TJ KEY PRESSED

Figure 4: The transmittersection of the remote key-board interface. This as-sembly will have its ownpower supply that allowsit to stand alone at a re-mote area. All resistors are114 W and all resistancesare measured in ohms.

) FROM KEYBOARD

iZXXXX'.To

COMPUTER

received, the data available line goes high.This signal is delayed and inverted and usedto reset the data available line. The result ofthis circuitry is that the data available linewill remain high only for the duration of thetime delay set by the resistor and capacitorat the input of the CMOS inverter. If yoursystem will not accept a 1 0 ms data readystrobe, then dispose of the CMOS gate andreset pin 18 via a computer output strobe orsome other synchronized means.

The last point of discussion is the linedriver and receiver. RS232C seems to be thestandard, but this would require a plus andminus 12 to 15 V power supply for thedrivers and receivers. The limits of mostmicroprocessor power supplies are usuallywithin +12 V and -12 V. Let's be practicalfor a moment. We aren't stretching a 1 milecable along an arc welding line at an auto-mobile plant (as occasionally happens whenworking with industrial automation as I dofor a living). What we have is I 00 to 200 feetof twisted pair in a relatively low noiseenvironment. RS232C is for industrial en-vironments, and is not necessary for thisapplication. 5 V line drivers are quite accept-able in this application, and a 7440 NAND

Table 2: Power pin assign-ments for the receiver andtransmitter of figures 3and 4.

IC

Number

Type

+ 5 V

GND

-12 V

1

AY-5-1013

1

3

2

2

DM8820

14

7

3

NE555

8

1

4

4009

16

8

5

AY-5-1013

1

3

2

6

DM8830

14

7

7

NE555

8

1

gate could be used as an appropriate driver.A somewhat preferred approach is to use5 V differential drivers and receivers such asthe DM8820 and DM8830. These NationalSemiconductor (or their Texas Instrumentsequivalents SW75182 and SW75183) devicesmay not be available everywhere. ATexas Instruments 75107 and 75110 com-bination with the appropriate pin numberschanged can be used instead.

Construction is straightforward, andcheckout is a simple go or no go test. Makesure that all voltages are correct and that thekeyboard inputs to the interface operatecorrectly. It is a good idea to use a fre-quency counter to set the 1760 Hz on boththe transmitter and receiver cards. If thefrequencies are not within a few percent ofeach other, it will not work.

Attach a 1 or 2 foot twisted pair leadbetween the two units, plug in the keyboard,and remove the CMOS inverter from thereceiver card. To display the received dataword, either connect the receiver output to acomputer parallel input port and write aprogram to scan and display it, or attachsome sort of LED buffer and driver kluge todisplay the output.

When a key is pressed on the keyboard,the ASCII code for that key should appearat the receiver output. Momentarily ground-ing the data available reset line will allowanother character to be received. When thisphase is accomplished, insert the 4009,string your 200 feet of twisted pair cable,hook your monitor up with 200 feet ofcoax, and start plinking away."

54

Two Bytes Ape Better Than One

W'

W 0?

*#

/

Ml

TEXASINSTRUMENTS

TMS 990016BIT

^i'™;*'

MICROPROCESSOR

CONT CONl^ T GND. ADRS PWR\ DATA #1 »P

2K BYTEPROM

2K BYTESTy-E-PROM

RS232C

or20 MA, LOOP

8 VECTOREDINTERRUPTS

1 CHIPCLOCK

TMS2708E-PROMPROGRAMMER

FREE YOURSELF FROM THE ONE BYTE WORLD. MOVE UP TO THE TWO BYTE TEXAS INSTRUMENTS TMS-990016-BIT MICROPROCESSOR — WITH OUR — "SUPER STARTER SYSTEM" — TEC-9900-SS. SHOWN ABOVE, FEATURESHARDWARE MULTIPLY AND DIVIDE, 69 MINI-COMPUTER INSTRUCTIONS, 7 ADDRESSING MODES, EXPANDABLETO A FULL 65K BYTES; MONITOR, TMS 9900 CPU, RAM, P-ROM, E-PROM, PROGRAMMER ALL ON ONE P-CBOARD BASIC OPERATING SYSTEM AS LOW AS $299 UNASSEMBLED $399 ASSEMBLED AND TESTEDEXPLICIT MANUAL INCLUDED OR AVAILABLE SEPARATELY AT $35, TO LEARN MORE . . .JUST TEAR OFFA PIECE OF THIS AD, PIN TO YOUR LETTERHEAD & RETURN TO TECHNICO OR CALL OUR HOTLINE 1-800/638-2893TO RECEIVE FREE INFO-PACKAGE. —DESIGN & TECH SUPPORT BY ROSSE CORP.

TECHNICO

INCORPORATED

9130 Red Branch Rd.

Columbia, Md. 21045

301-596-4100

THE TECHNOLOGY LEADER INELECTRONICS DISTRIBUTION

Joseph J Carr

Bioelectronics Laboratory

The George Washington University Medical Center

901 23rd St NW

Washington DC 20037

Interfacing With an

The jobs which a computer can performrequire some method for interfacing with theoutside world. Most of us are familiar withthe requirements and abilities of the manydigital peripherals, but lack any practicalinsight into the use of analog 10 signals. Tomany, especially those oriented toward soft-ware, doing anything in the analog worldseems like an anachronistic art form, or froma technical point of view, a lot like trying toskin an amoeba. However, the analog worldexists, and some means must be provided forinterfacing the computer with it. Since mostdevices and machines in our world areanalog, this will extend your computerhorizons more than you may appreciate. Soif you want to put your machine to the taskof some really serious work, the time hascome to learn about some of the require-ments of analog electronics.

Several problems present themselves inthis area. We must understand something ofthe measurement of physical and electricalparameters from the real world, amplifica-tion and signal processing, analog readoutdevices, and conversions from analog todigital or vice versa.

Transducers

A transducer is any device which trans-forms a measurement of a parameter fromone form to another for purposes of mea-surement or control. We will modify thisdefinition a little to also specify that, for our

purposes, the parameters we measure areconverted to electrical signals. We will alsoconsider devices which are merely electrodesto pick up existing potentials, as in bio-medical applications, and also those whichwill only produce a switch contact closure ifcertain conditions are met. An example ofthe latter is the thermostat in your home.

Transducers are available for almost anytype of physical parameter or phenomena.Assorted manufacturers offer devices thatwill produce an output voltage that isproportional to physical parameters such asforce, strain, pressure, temperature, light,position, flow or a host of other variables.

The function of a transducer leads us tounderstanding just what we mean by analogelectronics. Most people will tell you that ananalog signal is one which is constantlyvarying, as opposed to digital signals whichmay have but two states. A more reasonabledefinition also takes into account that thevoltage or current input to the circuit is anelectrical analog of some physical parameterbeing measured. In this case, the wordanalog is related to analogous.

The number of different types of trans-ducers prevents us from being too specific inthis context, so we won't even try except topoint out that most transducers which youwill encounter will be resistive and have aWheatstone bridge circuit such as is shown infigure 1. The voltage, E, must be regulated inorder to prevent variations in the excitation

56

Figure I: A basic resistive transducer in Wheatstone bridge form. The circuitproduces an output voltage that follows the relationship:

E„

R2

R4

Rl + R2 R3 + R4

The excitation voltage E is usually between 0 V and 10 V for most commonforms of transducers. It may be either AC or DC, but DC types may be pre-ferred for simplicity.

Analog World

potential from showing up as artifacts in thetransducer output signal. I have used LM309and 7805 three terminal integrated circuitregulators for this function with goodsuccess.

Determining the Resistors forthe Right Job

In most transducers of the class which weare considering, resistors Rl through R4 willchange resistance with changes in the appliedparameter being measured. Although sometransducers, notably temperature types, willhave only one or two resistors of theWheatstone circuit variable, most will allowall four to vary with the applied stimulus.Those resistors which do not vary are fixed,of course.

The nature of the resistors in the bridgewill depend totally on the type of phe-nomena or parameter being used to stimu-late the transducer. Thermistors, forexample, are appropriate if it is tempera-ture that is being measured. Piezo-resistivestrain gauge elements, on the other hand,may be more appropriate for measurementof force, pressure and so forth. A simplelinear taper potentiometer may be used tomeasure position. For the casual designerwith but moderate requirements, the onlyspecifications of real interest are such itemsas the maximum and minimum range, line-arity and sensitivity.

The range is the maximum and minimumvalues of the applied parameter which can beaccommodated. A pressure transducer, forexample, might be specified over a rangeof -100 Torr to +400 Torr (1 Torr = 1 mmHg). It is necessary to know just whatthe manufacturer of the transducer meanswhen range specs are given. The figuresquoted might be destruction points or theymight be the range over which other specs,such as linearity and sensitivity, are guaran-teed. In either case, though, the range limitsshould not be exceeded.

Desirable Qualities

Linearity is a measure of how well thetransducer output follows variations in theapplied parameter. This is usually quoted asa percentage of either full scale, or some testpoint, at which the device is calibrated.Linearity can be thought of as a measure ofhow good the transducer is — in otherwords, how analogous the output voltage isto the input stimulus. You will find that, ingeneral, linearity can be expensive; thehigher the cost, the better the linearity.

Sensitivity is one specification of primaryinterest to the instrument designer. Onemethod for denoting this specification is interms of transducer output voltage per unitof applied stimulus per volt of excitationpotential. This might be stated as:

S = X /iV/V/unit stimulus

57

Figure 2: The basic figure for a 741 operational amplifier with power con-nected. The inverting terminal (—) produces an output signal that is 180 outof phase with the input voltage. The noninverting input terminal (+) producesan output that is in phase with the input. It should be noted that the pinoutsshown are for the 8 pin dual in line (DIP) and metal can packages. This par-ticular circuit also comes in dual in line packages with two or four amplifiersections sharing common power supply pins.

A pressure transducer, for example, might berated at a sensitivity of 1 00 ,uV/V/10 Torr.Assuming the common excitation potentialof 5 V DC, this tells us to expect an outputvoltage of:

100/iV/V/10Torrx5 V

50 nVTorr

A pressure of 100 Torr, then, will produce avoltage of:

50 ^VTorr

x 100 Torr = 5000 ji/V, or 5 mV

Analog Signal Processing

The processing of analog signals is onearea where analog and digital buffs arefrequently at dissonance with each other. Tobe sure, many of the functions of analogsignal processing can be done equally well ineither field. In some areas there may be aclear bias in favor of either analog or digitalapproaches.

The normal signal processing functionsmay be considered to be amplification,filtering, compression and so forth. Amplifi-cation seemingly becomes easy in softwarebecause it is merely necessary to multiplythe input voltage, represented by a digitalword, by some constant called the amplifi-cation factor. This is less easy than mayappear at first blush because the input mightbe too low to take full advantage of theanalog to digital converter's range.

Filtering is an area where software signalprocessing has really come into its own. Infact, it is possible to design a software filterthat is a lot better than all but the mostcostly hardware analog filters. The problemcomes in trying to implement the softwarefilter in a limited amount of memory. Onsystems with a small amount of memorycapacity, say less than 1 K bytes, the hard-ware filter might be more useful.

Another aspect of signal processing is thederivation of parameters. For simplicity ofhardware design it is sometimes easier tomeasure one parameter than another. Withthis in mind, the actual electronics can oftenbe kept simple prior to the analog to digitalconversions. It is often possible to usesoftware to do unit conversions and com-pute derived parameters from related, buteasier to measure, parameters.

o OUTPUT

NON-INVERTING •

INPUT

Amplifiers

A computer will want to see an input inthe form of a digital signal flag or an n bitword. Since the analog instrument may onlyproduce a voltage or current level thispresents a problem. In that event a suitableconverter is required. It must be noted,though, that many modern digital instru-ments used in science and engineering, es-pecially those with digital readout, willprovide rear panel digital output, usually inBCD (binary coded decimal) form.

Most common analog to digital convertersaccept full scale input signals over a limitedrange, for example, between ±5V, 0 to+ 10 V, or 0 to +5 V. The typical transducer,on the other hand, may want to output onlya few millivolts or less, a level that may wellbe in the noise as far as the analog to digitalconverter is concerned. In such cases, itwould be necessary to provide intermediateamplification.

Although numerous approaches to ampli-fication exist, the integrated circuit opera-tional amplifier is probably most applicableby the largest number. In fact, many smallcomputer systems already have the ±12Vpower supplies usable for operational ampli-fier chips. In most of the applications whichyou will find, the familiar 741 type opera-tional amplifier is probably the best bet. Itcomes in several package styles and has twoendearing qualities: It is forgiving of novicedesigners and it is quite inexpensive, typi-cally less than $1.

It is obvious in the limited context of thisarticle that I cannot fully describe either theoperational amplifier in its glory, or even thefull spectrum of its uses. For those inter-ested let me refer you to my book Op-AmpCircuit Design and Applications (Tab Books#787). For this present discussion we shalllimit ourselves to the basic rules governingoperational amplifier circuits of use to you.

The symbol for the basic operationalamplifier can be seen in figure 2. Note thatthere are two different power terminals andthat neither is normally grounded. Althoughyou will see some circuits in which one

58

Figure 3: This circuit is a simple invertingamplifier. It will produce an output voltageaccording to the relationship:

-out

-A x £/,

The voltage gain factor A is equal to theratio Rf/R/n. There are restrictions on thevalue of this ratio which must be met inorder for the operational amplifier tofunction properly (see text).

E IN

E OUT

PIN NUMBERS SHOWNFOR 8-PIN DIP OR8-PIN METAL CAN

ftl

power terminal is grounded, in normaloperation a symmetric dual power supply isused. The +V terminal is always connectedto a supply that is more positive than the—V terminal however the circuit is con-figured. Symmetric potentials appropriatefor most operational amplifier integratedcircuits now available range between ± 4 Vand ±15V. Certain special or premiumdevices extend the limits on each end by acouple of volts.

Simple Inverting Gain Follower

An ideal operational amplifier wouldallow universal application with any gainfactor (see figure 3), but real operationalamplifiers impose certain constraints on thedesigner. For example, it is not wise to allowthe value of R|n to drop below 5 to 10 timesthe impedance of the transducer or otherdriving source. A transducer might, forexample, have an effective impedance (resis-tance) of 100 ohms. In this case, theminimum acceptable value for Rjn would be1000 ohms. Similarly, other transducerswith higher effective impedance woulddemand higher input impedances of thefollowing amplifier.

Problems of another sort will show up ifthe value of Rf is greater than 2 megohms,or so. This is especially true if operationalamplifiers of the low cost 741 family areused. In general, then:

1.

Rjn should be at least 10 times the

effective impedance of the drivingsource.2. Rf should be less than a couple ofmegohms unless high grade operationalamplifiers are used.

A further rule that is not strictly neces-sary, but seems to make things a little easier,is to avoid trying to get too much gain outof a single stage. Try to limit the gain in anysingle stage to some figure in the "under200" range. If greater gain is required, go toan additional stage. Operational amplifiersare cheap, in most cases, so it can bepenny-wise and pound-foolish to try to getall your gain out of one.

Noninverting Followers

The noninverting operational amplifierfollower (see figure 4) provides an outputthat is in phase with the input signal. It alsoprovides a much higher input impedance.

The input impedance of an invertingfollower is limited by the value of inputresistor Rjn. The noninverting follower, onthe other hand, has an extremely high inputimpedance. If a premium operational ampli-fier integrated circuit is selected, then it maywell be over 1 megohm. This is high enoughto be useful with almost any imaginabledriving source with a voltage output. Onlycertain high output impedance current trans-ducer sources would require higher amplifierinput impedance.

Differential Amplifiers

A differential amplifier will produce anoutput voltage proportional to the differ-

Figure 4: A noninverting amplifier. With the input signal applied to the non-inverting (+) terminal, the output polarity will be the same as the input. Theoutput voltage can be taken as the sum of the voltage drops across R/n andRf if the voltage across the operational amplifier Vac is taken as zero. Thus,the voltage gain A follows the relationship:

A =

Eout Rf+Ri

-in

R

in

59

Figure 5: This is the basic diagram for a differential input amplifier. It isbasically a combination of inverting and noninverting amplifiers. The outputvoltage will be:

Eout=f-(E1-E2)

This is provided that Rj = R2 and Rj = R4. Because this circuit tends toreject signals common to both input lines it is used to minimize interferencepicked up in wires connecting the transducer and its electronics.

encc between the two potentials referencedto ground as seen by the inverting andnoninverting inputs. Almost all commercialoperational amplifiers can also be used asdifferential amplifiers.

Figure 5 shows one type of differentialamplifier that offers the economy of re-quiring but one operational amplifier.

This amplifier will serve nicely wherecompactness is required and both moderategains (less than 500) and relatively low inputimpedance can be tolerated. Even the lowly741 will serve nicely in this circuit. Highergains and higher input impedances are pos-sible with higher grade operational amplifierssuch as the 725.

Another approach to higher gain andmuch higher input impedance which stilluses operational amplifiers of moderate costis the instrumentation amplifier of figure 6.

Operational amplifiers A'l to A3 can be741 devices in many cases, but it is con-sidered wise to use premium quality ampli-fiers for A'l and A2 in even moderatelycritical applications. The 1456 is a goodchoice in these cases, while the 725 orseveral equivalents are best in tight cases.

Resistor R8 is a multiple turn poten-

tiometer used as the common mode rejec-tion control. The ideal differential amplifierwill only respond to a differential voltagebetween the two inputs. Unbalances anderrors in real operational amplifier circuits,though, make it possible for the amplifier torespond to a common-mode voltage which isshared by both inputs. R8 is adjusted to nullthe output voltage under conditions whereboth inputs are tied together and a signal ofseveral volts is applied to their commonjunction.

Some Comments on Practical Circuits

Any of the circuits shown in this articlemay be made workable by almost anybuilder with even moderate electronic assem-bly skills. It is only necessary to follow therules that are given. It must be noted,though, that a lot more is possible withoperational amplifiers, but would requiresomewhat greater design acumen. The rulescan be violated by the sophisticated designerbecause they are selected to be the "mosttrue for the biggest number." Next month,I'll continue with a discussion of somepractical applications of operationalamplifiers."

R8 (CMR ADJ)

100 Rl 2000

R2- R3R4-R5R6-R7+R8

Figure 6: This circuit can be described ascombining the simple differential amplifierof figure 5 and two copies of the noninvert-ing gain follower of figure 4. The voltagegain A is given by:

A

7 + K •

2xR2\ lR6\-W) X \R4)

This equation assumes that R2 is equal toR3, R4 is equal to R5, and R6 is equal tothe sum (Rl + R8j. Also, it is wise to keepRl between 100 and 2000 ohms in mostcases with contemporary operational ampli-fier integrated circuits.

60

Peripheral Vision

impacts

your computer.

WITH A

FULL-SIZE,

LOW-COSt

IMPACT

PRINTER.

Until now, the hobbyist and small businessman have had one major problem in assemblinga reasonably price microprocessor system with the capabilities found in the more costlycomputers. It was impossible to find a high-quality, high-output printer for hard copy needs atan affordable price.

Peripheral Vision has come up with a solution.

We are offering a full-size impact printer designed for microprocessors—and it comeswith a mini price. Kit prices start as low as $495 for the printer and interface card. And that won'timpact your pocketbook.

Peripheral Vision's printer is loaded with capabilities. Take a look:

• It's fast—120 characters per second

• 96 characters per line, 12 characters per inch horizontal, 6 lines per inch

• Makes up to 4 copies simultaneously

• Character set and pitch variable under software control

• 5 x 7 character matrix

• Ribbon has built-in re-inkers for a life of 10,000,000 characters

• Paper can be either a standard 81/2-inch roll, fanfold or cut page

• Interfaces to 8-bit parallel ports

Just remember, Peripheral Vision is committed to helping you get along with your computer.The new printer we are offering is another example. It is high quality, low in cost and willdefinitely impact your system.

Write or call now to find out how to impact your computer.

p

p

i<r>

0(M^

P.O. Box 6267 Denver, Colorado 80206 (303) 777-4292

What's in a

Floating Point Package?

Sheldon Linker

3514 Boelter Hall

UCLA

Los Angeles CA 90024

Byte 1

If you have been using computers for anylength of time, or have used a calculator,you know the value of floating point num-bers. In this article, I will endeavor to showhow floating point works and how to use it.

Initially, you must understand the repre-sentation of real numbers. In the decimalsystem, a real number may have a sign, adecimal point, digits to the left or right ofthe decimal point, and an exponent. Thegeneral form is commonly referred to asscientific notation. This form is:

±N.NNNNNNX10±MM

where N.NNNNNN is the "mantissa" andMM is the "exponent." Unfortunately,decimal numbers are hard to deal with, evenwith the decimal add or adjust instructionsof some microprocessors. There are somesimplifications that can be made withoutserious loss of precision:

Byte 2

Byte 3

Byte 4

Exponent Mantissa

Exponent Sign

Mantissa Sign

Example: The value of hexadecimal 013243F7is hexadecimal 0.3243F7 X 161or hexadecimal 3.243F7or decimal 3.141593

Figure I: Details how the floating point number may be stored in memory. Inthis format the first byte contains the exponent, the sign for the exponent,and the sign for the mantissa. Bytes two, three and four contain the mantissaof the number in absolute value form, with 24 bits of precision.

1. It is easier to handle the numbers if allof the digits are on the same side ofthe decimal point. This simplifies theshifting used to "normalize" resultsafter a multiply or divide instruction.The decimal form of this is:

+.NNNNNNNX10±MM

2. The exponent base should, for sim-plicity of programming, be a power of2. Assuming that a 6 bit (excludingsign) exponent is to be used, table 1helps in selecting the base by givingthe magnitude range (in decimal) for a6 bit positive exponent.

For the sake of conformity to manyexisting floating point packages, you shouldeither use a base of 2 or 16. A base of 2 givessomewhat limited dynamic range; so for therest of the article, I will use base 16. Thedynamic range is defined as the differencebetween the high decimal value of theexponent and the low value. This reducesthe generalized form to a more specific case.

t.NNNNNNNXieiMM.

Another consideration is storage. So far, Ihave 6 bits allocated to the exponent, 1 bitfor the sign of the exponent, 1 bit for thesign of the mantissa, and some amount forthe mantissa itself. As one byte has alreadybeen used, another three would work outnicely. 24 bits gives a precision of 24Xlog2or 7.22 digits of accuracy (which is treatedas 7 for formatting purposes).

Taking all of the above into account, wenow have the real number stored as infigure 1. [This 4 byte format is similar to theformat used in an IBM 360 or 370 for singleprecision floating point.]

We now come to what you've beenwaiting for: arithmetic. Addition and sub-traction are the easiest, so I'll start withthem. In the algorithms I'll present, additionand subtraction are simplest when using only

62

positive terms; so the substitutions shown intable 2 can be made. Vertical bars denoteabsolute value as in |X| signifying the ab-solute value of X.

Table 2 actually boils down to a series ofadditions, subtractions and sign inversions.A flowchart of this process is given infigure 2.

When adding or subtracting, the first stepis to determine whether a number is nega-tive. When the first byte of a floating pointnumber is negative, then the entire numberis negative.

The second step is to change the sign of anumber. This is done by adding or exclusiveorring a hexadecimal 80 to the first byte ofthe number in this format.

You may notice that in the flowcharts Itook no action to take the absolute value ofeither the A or B terms. This is because themantissa bytes are actually in absolute valueform.

You are now ready for the next step inaddition or subtraction. Before the numberscan be used together, the exponents mustmatch. This is done by incrementing thesmaller exponent until it equals the largerexponent, while at the same time dividingthe corresponding mantissa by 16. The largerexponent becomes the exponent of theanswer up to this point. When comparing

Base

2

4

81632

Maximum Value

(Base raised to

64th power)

1.84 X 1019

3.40 X 1038

6.28 X 1057

1.16 X 1077

2.14 X 1096

Original Equation

Use

A+B A»0 B>0

A+B

A+B A>0 B<0

A- IBI

A+B A<0 B»0

B- IAI

A+B A<0 B<0

-(IAI +

IBI

A-B A»0B»0

A-B

A-B AJ*0 B<0

A + IBI

A-B A<OB>0

-(IAI +

B)

A-B A<0B<0

—(IBI —

IAI

Table I: A summary ofthe dynamic ranges, dif-ference between the low-est and highest expressablenumbers, of several dif-ferent bases. The bases areall powers of two sincethese are the easiest tohandle on a computer. Therange of the number isdetermined by assumingan exponent of 6 bits,excluding the sign.

Table 2: Substitutions thatmay be made when addingor subtracting. This tablereduces to a series of addi-tions, subtractions and in-versions which are per-formed by the routine offigure 2.

wdd-subtract)

CALL A0D2

YES

CALL SUB2

CALL ADD2

^

L

ANS=-ANS

Figure 2: Flowchart for aroutine which will manipu-late the two values to beadded or subtracted ac-cording to the rules sum-marised in table 2.

( RETURN J

63

FIX UP

DIVIDE

MANTISSA OFANSWER BY 16

INCREMENTEXPONENT OFANSWER

I

( RETURN J

Figure 4: This additionroutine adds the two num-bers and then checks ifthere has beep an overflowinto bit 25. If this condi-tion exists, the mantissa isdivided by decimal 16 andthe exponent is incre-mented by one, thus givinga 24 bit answer.

INCREMENTEXPONENTOF B

DIVIDE

MANTISSA OFB BY 16

"\ RETURN )

INCREMENTEXPONENTOF A

DIVIDE

MANTISSA OFA BY 16

Figure 3: The FIXUP routine manipulates the exponents of the two numbersso that they are equal. This is a prime consideration for subtraction andaddition routines.

one exponent to another, you must keep inmind that the exponent occupies only theright 7 bits of the byte. To convert it to astandard signed number, you have to extendthe sign by doing a shift left followed by anarithmetic shift right. Finally, you are aboutready to do the actual addition or subtrac-tion, but so that nothing is lost, you musttreat the mantissas as 32 bit fields. Aflowchart for the whole alignment step isshown in figure 3.

After the addition or subtraction youmay have a 25 bit number, taking intoconsideration the carry of the 24 bit man-tissas. If you do, divide it by 16 and add 1 tothe exponent of the answer, as shown infigure 4. If the exponent of the answer isnow 64, then you have the condition knownas overflow. This is usually considered asevere error and warrants slopping the pro-gram, or substituting a "default" value.

Alter the subtract, you may be left with anegative number or zero. If you are left witha negative value, set the sign indicator bit ofthe answer to I and change the sign of thedifference, as shown in figure 5. There is afinal step shown in figure 6, after the sub-traction called normalization. If the mantissaof the answer is less than hexadecimal

0.100000, multiply it by 16 and subtract 1from the exponent of the answer.

If the exponent is less than or equal to—64, you have a condition known as under-flow. The underflow condition is considereda minor error, and the accepted response isto set the answer to zero, print a warningmessage, and continue execution of theprogram.

Continue normalizing until the mantissais at least hexadecimal 0.100000.

To avoid the error of coming up with ananswer of —0, apply this simple test: If thefirst 16 bits of the answer equals hexa-decimal 8000, then the real answer is zero.Also, be sure to assemble the exponent intothe final answer along with the sign and themantissa.

After mastering addition and subtraction,we now forge onward to multiplication. Astheory tells us:

(AX16B) (CX16D) = ACX16B+D.

This makes things extremely simple. Stepone is to multiply the two 24 bit mantissastogether, giving a48 bit result. Don't scream!You probably already have a method of mul-tiplying two 8 bit numbers, giving a 16 bitresult. The method of multiplying and sum-

64

f SUB 2 J

CALLFIXUP

SUBTRACTB-A

CHANGESIGN OFMANTISSA

SET NEGATIVEBIT OFANSWER

CALLNORMAL

( RETURN 1

CALLNORMAL

f RETURN )

ming for a 48 bit answer is shown in figure 7.After carrying out the nine 8 by 8 multipliesshown, sum vertically. Throw away bytes Kand L of the result since they won't show upin the answer. Step two is to normalize bytesG, H, I and J. Bytes G, H and I now becomethe mantissa of the answer. Step three is tofind the sign of the answer. Since table 3applies to both multiplication and division,the exclusive or function can be used onbytes A and B to find the sign of the answer.Step four is to find the exponent. Separatethe exponents, as in the FIXUP routineflowcharted in figure 3, and add themtogether along with the exponent given bythe normalization process. Check for over-flow and underflow.

The rule for division is stated as:(AXI6B) * (CXI6D) = A^DX16B-D.

This is similar to multiplication, exceptthat the exponents are subtracted, alongwith the difference that you divide themantissas instead of multiplying. To multi-ply, you took two 24 bit numbers and got a48 bit product. To divide, you take a 48 bitdividend and a 24 bit divisor, giving a 48 bit

( normal J

" Figure 5: This subtractionroutine subtracts twonumbers and then de-termines the sign of theanswer. If the sign is posi-tive the answer is nor-malized and the number isthen returned to the call-ing program. If the answeris negative a positive num-ber is sent to the normali-zation routine and thenthe sign of the number isset negative before beingreturned to the callingroutine.

UNDERFLOWERROR

YES

ANSWER= 0

3

DECREMENTEXPONENTOF ANSWER

( RETURN J

Figure 6: This is a normalization routine for the floating point format used inthis article. The answer is set up so that the mantissa is hexadecimal 0.100000to hexadecimal .FFFFFF. This is accomplished by multiplying the mantissaby decimal 16 and then incrementing the exponent until the high nybble ofthe mantissa is from hexadecimal I to 16.

□ be

d

e

f

C X f

b x f

b x e

c x d

b x d

a x d

0 i

0 I

0 I 0

0 I 0

II

0 0

a h i j k

Figure 7: A summary of the method of multiplying two 24 bit mantissas toattain a 48 bit mantissa result. After the summation, the low order K and Lbytes may be discarded as they will not show up in the final answer.

65

Table 3: A summary ofthe sign of the answergiven the sign of the num-bers used in a multiplica-tion or division.

Signs

A»0 B»0A»0 B<0A<0 B»0A<0 B<0

Sign ofAnswer

( divide J

SET UP DIVI-DEND, DIVISOR,QUOTIENT, ANDHOLD REGISTERS

( RETURN \_\_ ERROR J~

YES / DIVISOR

DOUBLE DIVISOR

AND

HOLD REGISTERS

Figure 8: A division rou-tine for floating pointnumbers. This routinestarts with a 48 bit divi-dend and a 24 bit divisorto arrive at a 48 bit quo-tient. The routine thennormalizes the answer be-fore returning it to thecalling program.

SUBTRACTDIVISOR FROMDIVIDEND

ADD HOLDREGISTER TOQUOTIENT

HALVE DIVISORAND HOLDREGISTER

CALLNORMAL

( RETURN J

quotient. Unfortunately, there is no way tochain partial quotients together as can bedone with partial products. As you read thedescription of 48 bit division, please refer tofigure 8.

First, you must set up four 48 bit fields:the dividend, the divisor, the quotient andthe hold register. Second, set the 24 highorder bits of the 48 bit dividend to the 24bit dividend and the 24 low order bits tozero. Third, set the high order 24 bits of the48 bit divisor to the 24 bit divisor and thelow order 24 bits to zero. Then, set thequotient to zero and the hold register to I.

Now that the numbers are set up, nor-malize the divisor by multiplying it by 2until the high order bit is on. Every time thedivisor is doubled, the hold register is alsodoubled. Notice that if the divisor is zero, itwill never get normalized; so it's a good ideato indicate an error condition and abort theprogram if this is the case.

The next step is the repeated subtraction:If the dividend is greater than or equal to thedivisor then subtract the divisor from thedividend and add the hold register to thequotient. Then divide the divisor and thehold register by 2. If the hold register is stillnonzero, then keep performing the repeatedsubtraction. This leaves only the normaliza-tion and sign operations, as in multipli-cation.

This completes the summary of basicfloating point operations needed to do cal-culations in scientific notation. There areother formats which can be used, with moreor less precision, using BCD coding for themantissa and exponent, etc. The generalsteps required are all very similar. Otheritems which are useful to have, but which Ihave not covered here, include conversionroutines for input and output, and transcen-dental function evaluations. But even if youcan't calculate a sine or a cosine, and don'thave a flexible FORTRAN style formattingoutput, the basic calculations of addition,subtraction, multiplication and division canprove a useful adjunct to your software."

66

SOFTWARE

HARDWARE

Disk Operating System *Device management andexecutive scheduling *Directoried file manage-ment system *Sequential and indexed randomfile structure *Full support of all languages,utilities, and peripherals.

FORTRAN IV

ANSI FORTRAN compiler *Double precisionreal and complex arithmetic *Non zero basedarrays *reentrant subroutines *Random fileI/O *ISA process control, real time, and multi-tasking extensions *Chaining, swapping, and over-lays *Commercial subroutine package.

MACRO ASSEMBLER

Relocatable code generation *Macros *Dynamicinstruction definitions Conditional assembly.

EDITOR

Character or line oriented *String operationsfor search, search and replace *Store and exe-cute command strings *Multiple files openconcurrently.

Micro NOVA® 16 bit processor *Real time clock*Hardware multiply and divide *Power fail autorestart *8K bytes RAM *9 slot chassis withfront panel and power supply, (optional 18 slotchassis)

ASYNCHRONOUS SERIAL INTERFACE

Strap selectable data, parity, and stop bits*Modem control signals *Data rate strappablefrom 50 to 19,200 baud *EIA-RS232C or 20mainterface.

DEBUG ROM

Examine, deposit, control of memory and inter-nal CPU registers and status *Breakpointsfor monitoring running programs *Auto programload.

DISK

2 diskette drives per controller *315K bytesper diskette *31.5K bytes per second transferrate.

EXPANSION

Memory expansion in 8K and 16K byte incrementsup to 64K bytes *General purpose interfacesfor custom applications *9 slot I/O expansionchassis.

DISK SYSTEM

*CPU with 40K bytes RAM *Dual diskette *Asynchronous serial interface*CRT terminal *Debug ROM *DOS *FORTRAN IV *Macro Assembler *Editor*Utilities and support programs *Complete documentation set. $8400

Other systems available from $2700All hardware is fully assembled and tested.Support is available from service centersaround the country. Prices and specificationssubject to change without notice.

rra

If you are serious about computing, call or writetoday. BPI Inc., 2205 East Broadway, Suite 6,Tucson, Arizona 85719 (602) 326-6975

TechnicalFopum

The 8080 High Level

Language Project ofPeter Skye, Continued

Peter Skye, Chief Engineer

Watermark Inc

10700 Ventura Blvd

N Hollywood CA 91604

(213) 980-9490

In the August issue (see page 12), youpublished my letter about writing a highlevel language compiler for use on a micro-computer. I got quite a bit of response tothis project, and I'd like to fill your readersin on what is going on.

First Item

The following languages were mentionedas possibilities for a new compiler, withPL/I the overwhelming favorite. In orderof preference: PL/I, FORTRAN, BASIC,SNOBOL, PASCAL, COBOL, RPG,

Figure 7: Character set, in logical groupings. Where more than one version ofa symbol is in common usage, all are shown.

1) blank, 0-9, A-Z, a-z

2) Greek alphabet (upper and lower case). Must include

| £ summation symbol

II multiplication symbol

for APL

7T pi

3) ., : ; I ? ( )| } [ ]

APLsy

mbols

4) +

6) +

I

7)

$$$

-

+

r

£ct

- APL negative symbol

L

%

**#*

\

#

X

T

□

b musical flat symbol

j-

1

a

@

1

I

o

\

V

0

"

i

§

degrees symbol

&£

•

e

*-

A

• •

®®®

t

V

c

V

~*

<

D

A

\

>

r\

$

■

<

w

4

:. therefore symbol

>

II

=

/ integral symbol

"I

5) A combinatory symbol

FORMAC, TRAC, C, APL. ALGOL was notmentioned.

I chose an expanded PL/I (which I amexuberantly and unabashedly calling PL-SKYE) for the following reasons:

1. PL/I includes all of FORTRAN,BASIC, and ALGOL.

2. The main attraction of SNOBOL is afew string handling functions. Thesehave been incorporated into PL-SKYE.

3. PL/I includes all of COBOL, althoughthe format and syntax of COBOL isdifferent from PL/I.

4. RPG is a very simple language. RPGprograms are very easily rewritten inPL/I.

5. Only one person mentioned APL.Since APL's "thing" is the power in itsassignment statement, I have includedthe APL operators in PL-SKYE. Ques-tion: APL operators have no hierarchy,whereas PL/I operators do. What hier-archy should be implemented? (I havemade all the APL operators the same.)Come on, APL fans, write me thistime!

6. Format ability has been included inPL-SKYE.

7. I am unfamiliar with PASCAL, TRAC,and C, but the few people who men-tioned these languages didn't mentionanything they could do that PL/Icouldn't do.

Second Item

See figure 1 for the proposed characterset for PL-SKYE. This character set is largerthan those in common use, although nothingout of the ordinary for a textbook. Whichbrings up some questions:

I. Are there any symbols that I haveforgotten?

68

A STORY IN THREE ACTS

A P T I ' °ur story be9lns with the ACT'1hUI t ' terminal — the world's first Af-fordable Computer Terminal. The ACT-I isan exceptionally practical interface betweenman and machine for any computer systemwhich communicates over a serial ASCII link.Whether querying a microprocessor basedsystem or time-sharing on a major computernet, the ACT-I is the most economical meth-od of alphanumeric communication at datarates from 110 baud all the way to 9600 baud.The ACT-I video computer terminal managesa 1024 character display memory organizedas 16 lines of 64 characters chosen from thestandard upper case ASCII set. Receipt ofmore than 64 characters on a line or the 'CR'code initiates a scroll operation. The entirescreen may be locally cleared at any time bydepressing the 'CLEAR' key.

I/O SPECIFICATIONS

(JUMPER SELECTABLE):

DATA RATE: 110, 300, 600, 1200, 2400,4800, 9500 BAUD

PARITY: odd, even, or none

STOP BITS: 1 or 2

LOGIC LEVELS: RS232, TTL,or 20 ma loop

PRICE: $400

Jnm 71 Not to be upstaged by its excit-■IW ■ V ' ing predecessors, the ACT-IIIperforms with state of the art elegance andversatility. The ACT-III includes switchselectable display formats: 24 lines of 80characters; 48 lines of 40 characters; or 96lines of 20 characters. Transmission is alsoswitch selectable between three modes:character, line or page at a time mode. ThePRINT key sends the contents of the 1920character display memory out an RS232Cprinter port at rates up to 9600 baud. Foroptimum efficiency, trailing spaces on anydisplay line are excluded from transmissionand of course the printer rate is indepen-dently switch selectable.

Full cursor control, direct cursor addres-sing, protected data fields, and video inver-sion are all standard encodeable functions.Convenience features such as a videomonitor AC power outlet and a switch toinitiate a comprehensive terminal self test areavailable on the cabinet rear. The ACT-III isthe most complete video terminal available ata price far below that of the competition,smart and dumb alike.PRICE: $700.

APT? "The plot thickens. For remote

It U ■ M ' communication to a central pro-cessor MICRO-TERM introduces the ACT-II.The ACT-II includes all of the desirablefeatures of the ACT-I with the important ad-dition of an integral originate —only 300 baudmodem and acoustic coupler for a standardtelephone handset. The ACT-II (withoutmonitor) slips easily into a briefcase (4x 14x 11)and readily commutes with you.

The ACT-II's modem features 5 stages ofactive filtering as well as one passive stageto achieve the lowest possible error ratesdespite the noises present on Ma Bell's lines.

Want true CPU power for low cost? Inves-tigate the time-sharing systems in your area;the ACT-II can be your key to the tremen-dous libraries of debugged, documented,software which are available on these dial-up systems.

PRICE: $550.

GENERAL INFORMATION

All MICRO-TERM products are fully assembled, tested and guaranteed for 90 days.

The MICRO-TERM product line is available from stock at discriminating computer

stores or may be purchased directly from the factory (30-45 day delivery). Prices are F.O.B.

St. Louis, Mo. excluding video monitors. Optional high resolution video monitors are available

from the factory beginning at $125.00.

BankAmericard and Master Charge accepted.

Mj-

MICRO-TERM INC.

RO. BOX 93B7

ST. LOUIS, MO 63117

2. Is there any standard for bit represen-tations on these characters (IBMers,please check your "green cards" 'cause1 lost mine)? [Use ASCII. .. CH|

3. How hard will it be to implementthese characters on 5 by 7 dot matrixdisplays and printers?

Again, I'd appreciate your responses, espe-cially from manufacturers concerning #3.

Third Item

(Machine Language, Pie in the Skye)

One of the most common requests wasfor the ability to have in line "assembly lan-guage" statements. I have made the valuejudgement not to do this, for the followingreasons:

1. All of the examples of things "youcouldn't do" really can be done inPL/I, by using the built-in functions,iSUB capability, and list processing.And programming is faster this way,because you get accurate diagnostics.

2. In a properly designed high level lan-guage, there should be a function orkeyword to do the thing you're try-ing to accomplish, without having togo to assembly language. PL-SKYEwill be updated, just like the diction-ary, so that it will indeed do every-thing. (And it isn't "too big!") [Goodluck. . . CH]

3. If you put in statements which restrictyou to a certain processor, your pro-grams are not going to be compatibleon any other system. Listen, folks,processor independence is where it'sat. PL-SKYE will be written com-pletely in PL-SKYE. I had to add afew extra keywords to the language toaccomplish this, but that's what you'resupposed to do when you write abetter compiler.

Fourth Item

Relocatable code was mentioned severaltimes. Yes, PL-SKYE has this. Nobody men-tioned it, but relocatable code makes iteasier to get into a multiprogramming envi-ronment (play Star Trek, Pong, and cooksupper all at once!?), and allows concepts ofmodular programming and linkage editingnot possible otherwise.

Fifth Item

As to which processor to write for, peoplementioned the 6800, 8080, Z-80, and Micro-nova. Although my original intentions werefor a Z-80 system with floppy disk, I nowplan on having code for the other processorsas well. And, you won't have to have disk.

Sixth Item

Many people want the compiler's andprogram's 10 to be independent of someparticular peripheral device. It sounds likethey really want the IBM Operating System,which I'm not opposed to at all. But they'llhave to wait; that kind of code doesn'tbelong in a compiler. You'll have to compileyour 10 either directly to a peripheral, orthrough an IBM type of Data Control Block(DCB). How about somebody else writing agood OS (Operating System)? In PL-SKYE?

Seventh Item

Status of PL-SKYE? The original (pre-BYTE letter) version has had two majormodifications: The input token routine hasbeen expanded to accept APL operators, andthe code generation logic has been expandedto handle DECLARE statements internal tocontained blocks. I think the easiest way todistribute PL-SKYE will be on a phonographrecord, which you will play through yourRS 232. Any comments on this idea? | Whynot bar codes?. . . CH] ■

More Comments on PDP-8s(Or, "Over the Hill" Means"Worth Looking At")

I write this in response to the letters ofMr Simmons and Mr Gordon, regarding theviability of the PDP-8 as a computer for thehome hacker ["A Salute to the PDP-8 andFarewell" BYTE #74, page 138; "Commentson Design Evolution" BYTE #76, page 50/.In evaluating any computer for possible use,several factors are always present, such asprice, size, power consumption, reliability,software and so forth. Every user will havedifferent criteria; I would like to offer some

comparisons, based on a set of criteria thatmight be of interest to the home user, thatshow the PDP-8 in a much more favorablelight than either Mr Simmons or Mr Gordonshow.

Price: PDP-8s, 8/ls, 8/Ls are now avail-able on the used computer market for $750to $1200. These are for assembled, standalone units with 4 K of core memory,Teletype interface, etc. The PCM-1 2 is avail-able, as a kit, for about $1000 for the sameequipment (although with semiconductormemory). These prices arc very close to

70

XililcDiA P^EiEnUi

The SOROC10120

CURSOR CONTROL. Forespace, back-space, up, down, new line, return, home,tab, PLUS ABSOLUTE CURSOR AD-DRESSING.

TRANSMISSION MODES. Conversation(half and full Duolex) PLUS BLOCKMODE — transmit a page at a time.

FIELD PROTECTION. Any part of thedisplay can be "protected" to preventovertyping. Protected fields are displayedat reduced intensity.

EDITING. Clear screen, typeover, abso-lute cursor addressing, erase to end ofpage, erase to end of line, erase to endof field.

DISPLAY FORMAT. 24 lines by 80 char-acters (1,920 characters).

CHARACTER SET. 96 characters total.Upper and lower case ASC11.

KEYBOARD. 73 keys including numerickey pad.

REPEAT KEY. 1 5 cps repeat action.

DATA RATES. Thumbwheel selectablefrom 75 to 19,200 baud.

SCREEN. 12 inch rectangular CRTphosphor.

P4

SPECIAL INTRODUCTORY PRICING

Kit $995.00 Assembled $ 1,295.00

(Price includes block mode, lower case and 24line options.)

IMSAI + Z-80

XIMEDIA is offering a special price on an IMSAII-8080 with a TDL ZPU Z-80 board instead of thestandard 8080 cpu.

The system includes:IMSAI I-8080 without cpu board. 22 slot motherboard with 22 pre-soldered connectors and cardguides; cooling fan.

Price:

Kit

Assembled

$999.00

$ 1,295.00

XIMEDIA OFFERS A FULL RANGE OF PRODUCTS FORTHE PERSONAL COMPUTER ENTHUSIAST AND THESMALL SYSTEM DESIGNER. LET US QUOTE ON ALLYOUR HARDWARE AND SOFTWARE NEEDS.

OUR RETAIL STORE - THE COMPUTER ISTxm - IS NOWOPEN IN SAN FRANCISCO. CALL US FOR DIRECTIONS.

Selectric Terminals

$1,200.00

AT LAST!

An ASCII coded Selectric terminalwith a RS232-C interface.

Call or write us today for details.

XililEDiA

1290 24th Avenue . San Francisco, CA 94122

(415)566-7472. Please call collect!

California residents add 6% sales tax. Please allow 3 weeks for delivery.

those of unassembled Altair 8800 or IMSAI8080 machines with similar equipment.

Software: No contest - the PDP-8 hasmore, software available than any othermachine in the mini or microcomputer class:two disk monitor systems, a real time systemwith batch mode, four assemblers, threeeditors, a variety of FORTRAN systems,DIBOL, FOCAL, several BASIC systems,and numerous special purpose packages.

Speed: This may come as a surprise, butthe PDP-8 is up to twice as fast as the 8080aand 6800 in many applications. The PDP-8will execute a 12 bit memory to accumu-lator add in 3.0 /is; the 8080a does theequivalent with 8 bits in 3.5 /is, at 2 MHz.The PDP-8 is thus processing data at 1.75times the rate of the 8080a for this re-stricted example. Granted, the comparisonof two machines for throughput rate isdifficult, but any other example, includingassorted test routines, will show the PDP-8to be the equal or better than the 8080a, orother microprocessors. While the IM6100,operating at 4 MHz, is slightly slower thanthe 8080a, the high speed IM6100A operatesas fast as a PDP-8/E, giving a speed of 2.5 /isfor the above mentioned instruction ex-ample. The IM6100A thus operates at a ratecomparable to the 4 MHz version of theZ-80 microprocessor.

Architecture: The PDP-8 is repeatedlycalled a primitive machine, and both MrSimmons and Mr Gordon make much ofcomparing it to the 8080a, among others.But consider these facts: The PDP-8 has trueindirect addressing; the 8080a and 6800 donot. The "cute" auto index registers, con-trary to Mr Simmons' feelings, are quitepowerful, and are used in virtually all soft-ware for the PDP-8 to good advantage. Thestatement that "... no program is reallyquite sure they are not used by some otherprogram ..." makes little sense. The micro-programmed instructions, while confusing atfirst, allow the PDP-8 to do some operationsin one instruction that take several in a8080a or 6800. For example, the skipinstructions allow testing up to three con-ditions at once, something which would takethree jump instructions in a 8080a. ThePDP-8 and 8/I have optional hardware multi-ply/divide. The IM6100, while not availablewith this option, can implement a vectoredpriority interrupt structure with the PIEchips that are made for this device. Thepaging structure of the memory is a nui-sance, and the subroutine linkage is incon-venient; however, since all PDP-8s have corememory, the fact that read only memory orprogrammable read only memory cannot beused is less of a problem than with the new

microprocessors, which generally use semi-conductor memory. Note that this is nottrue for an IM6100 based machine, andsome form of external storage is required inthis case.

Power consumption: This is a very realconsideration, since most home hackers canill afford the extra cost of running a powerhungry machine. Here, the PDP-8 is at adefinite loss; a PDP-8 uses about 500 W, an8/I or 8/L about 300. This is over twicewhat a typical 8080a based system uses.However, the IM6100 is a CMOS device, anda machine based on it would use less powerthan other micro machines.

Interfacing: Here again, the PDP-8 is insecond place. Without building a specialinterface, all the new Altair bus products areunavailable to a surplus PDP-8 user. On theother hand, numerous surplus devices areavailable for interfacing to the PDP-8.

Memory: A fully expanded PDP-8 mem-ory holds 32,768 12 bit words. This isequivalent to 75% of a fully expanded 8080aor 6800 memory, in terms of raw storage.While not as much as the new machines'capacity, this is still quite a large amount,and adequate for nearly any application.

I would like to offer some final thoughtson word length and design obsolescence. Inwhat holy book is it written that a computermust operate on multiples of 8 bits? The 12bit word of the PDP-8 makes it more adeptat multiple precision arithmetic; the 8080aand 6800 are more comfortable with char-acter oriented data. To offer some per-spective, the IBM 360/370 series works on 8bit characters, while the CDC 6600/7600uses 60 bit words for fast arithmetic. TheIBM 1620 used 6 bit characters for storage;both Mr Simmons and Mr Gordon will findthat, historically, word length has had littleto do with the relative merit of a computerdesign. As far as design obsolescence goes, adesign becomes obsolete when its price toperformance ratio no longer competes wellwith other designs. It is interesting to notethat Digital Equipment is selling more ofthose "old war-horse" PDP-8 computerstoday than ever before; obviously it is nicelymeeting the needs of someone -- a clearindication its price to performance is stillquite competitive. I submit that, on the basisof all this, the PDP-8 and IM6100 are bothworth considering by the home hacker forhis or her system. This "over the hill"machine, as well as the IM6100, will prob-ably be around, and quite useful at that, forseveral more years.

Ronald B Howes Jr

5753 Emerson Av S

Minneapolis MM 55419"

72

ANNOUNCING THREE

NEW BREAKTHROUGHS

INSOLDERLESS

BREADBOARDING.

Whether you design or build circuitsfor fun or for profit, you owe it toyourself to discover how fast andeasy CSC solderless breadboardingcan be. Now, more than ever. Be-cause of three new breakthroughsin breadboard design. And our newEXPERI MENTOR™ sockets**thatmake the most of them.1. Price Who says a quality bread-board has to be expensive? For aslittle as $9.95, CSC's EXPERIMEN-TOR sockets let you design, as-semble and modify circuits as fastas you can push in—or pull out-component leads. On a ruggedone-piece socket with 550 solder-less tie-points (94 five-point termi-nals and two 40-point bus strips).

Sockets lock together, snap apart tohandle any size circuit with ease.

But don't let the low price foolyou: EXPERIMENTOR sockets areprecision-molded of durable, abra-sion-resistant material, and featureCSC's non-corrosive, prestressednickel-silver contacts for positiveconnections and longer life. Allcontacts are identified, too.. .withmolded-in designations for easiercircuit assembly and diagramming.

2. Compatibility esc

EXPERIMENTOR sockets end the"big-chip blues'.' They're the onlyones with full fan-out capabilities formicroprocessors and other largerDIP'S, as well as 4-16-pin units. EX-

PERIMENTOR 600's 6/10" centeris ideal for microprocessor's, clockchips, RAM's, ROM's, PROM's, etc.While EXPERIMENTOR 300's small-er 3/10" center is perfect for smallerDIP's. Both units, of course, accepttransistors, LED's, resistors, capaci-tors, pot's-virtually all types of com-ponents with plug-in ease. As wellas #22-30 solid hook-up wire forinterconnections. Eliminating heatand lead damage to expensive com-ponents. And saving you moremoney, on carts.

Mix or match both models; arrangethem vertically or horizontally.

3. Flexibility with esc ex-peri mentor sockets, you canarrange your breadboard to suityour circuit... instead of vice versa.An exclusive snap-together inter-

locking system lets you instantlyconnect them. Vertically or hori-zontally. So you can mix or match3/10 and 6/10" centers...expand-ing or contracting to meet yourrequirements.

CSC EXPERIMENTOR socketscan be used alone, or mounted onany convenient flat surface, thanksto molded-in mounting holes andvinyl insulation backing that pre-vents shorts. You can mount themwith 4-40 flat-head screws from thefront, or 6-32 self-tapping screws,from the rear. But however you usethem, EXPERIMENTOR sockets arean unbeatable way to build and testtwice the projects in halt the time.

EXPERlMENTORfi

eogmillHllS

il!l)llllli!l!HH!

Both models feature 94 five-point

terminals (vertical lines) and two

■18 point bus strips (one strip shown).

WHY WAIT? CSC EXPERIMEN-TOR sockets are available now fromyour CSC dealer, or by phone fromCSC, at $9.95* for the 300 and$10.95* for the 600. Call 203-624-3103 (East Coast) or 415-421-8872(West Coast) — major credit cardsare accepted.

•Manufacturer's suggested list price.

Prices subiect tochange without notice.

U S Pat No D235.554

CONTINENTAL SPECIALTIES CORPORATION

44 Kendall Street. Box 1942, New Haven. Ct 06509

203-624-3103/TWX: 710-465-1227

West Coast office: Box 7809, San Francisco, CA 94119

415-421-8872/TWX: 910-372-7992

synchro-sound enterprises

"THE COMPUTER PEOPLE"

" IN STOCK "

NEW LEAR SIEGLER ADM - 3A KIT

FULL ADDRESSABLE CURSOR

CHARACTER GENERATION

5x7 dot matrix.

DISPLAY FORMAT

Standard: 1920 characters, displayed in 24 lines of

80 characters per line.

CHARACTER SET

Standard: 64 ASCII characters, displayed as upper

case, plus punctuation and control.

COMMUNICATIONS RATES

75, 110, 150, 300, 600, 1200, 1800, 2400, 4800,

9600, 19,200 baud (switch selectable).

IMSAI 8080 MICROCOMPUTERPOWERFUL • EASY TO USE • LOW COST

$619.95/22 SLOT MOTHER BOARD849.95/WITH Z-80 CPU

COMPUTER INTERFACES

EIA standard RS232C and 20 mA current-loop

(switch selectable).

DATA ENTRY

New data enters on bottom line of screen; line feed

causes upward scrolling of entire display with

top-of-page overflow. Automatic new line switch

selectable, end-of-line audible tone.

ADM-3A KIT $ 895.00

ADM-3A ASSEMBLED 1099.95

LOWER CASE OPTION 89.00

FOLLOWING ITEMS IN STOCK TDL, OAE,PROCESSOR TECH., SWTP, APPLE, HAYDEN,TARBELL, IMSAI, LEAR SIEGLER, OKIDATA,DEC, JAVELIN, TELETYPE ASR-33, TRW.

SPECIAL 9" JAVELIN HIGH RESOLUTIONVIDEO MONITOR $159.95

*****************

* 2708 EPROM $59.95 *

* Set of seven $350.00 *

*****************

DECwriter II

($1099.00)

OKIDATAMODEL 110

110CPS DOT MATRIX LINE PRINTER

FRICTION FEED*

TRACTOR FEED

RS 232C SERIAL INTERFACE

$1099.00

1229.00

250.00

■K -K * *

•K*-K*+:**+c-»:+:*-fc+:*

MOST ITEMS IN STOCK FOR SAME DAYSHIPPING. FULL MODERN REPAIR FA-CILITIES ON PREMISES-WE SERVICEWHAT WE SELL.

synchro-sound enterprises

$1769.95

Features

132 column printing

30CPS

Full Keyboard

Tractor Feed

NEW COMMERCIAL QUALITY KEYBOARD

The Model SS-1 Communications Terminal is anon-contact capacitive keyboard with a guaranteedlife of over 100,000,000 operations.FEATURES

• MOS/LSI Encoder with high reliability and lowpower consumption

• n Key Roll Over which eliminates operator errorand increases thruput

• Hysteresis for tease proof operation

• Solid State performance at mechanical switchprices

• Tactile Feedback at the operate point

• ASR-33 Array with four mode encoding

193-25 Jamaica Ave., Jamaica, NY 11423Phone (212)468-7067

HOURS 9 - 4 DAI LY + SATURDAY

BANKAMERICARD MASTER CHARGE

VISIT OUR NEW SHOWROOM

WORKING UNITS ON DISPLAY

KEYBOARD KIT $ 79.95

ENCLOSURE 39.95

(WITH NUMERIC CUTOUT)

NUMERIC PAD 29.95

COMPLETE KIT (with pad) 139.95

ASSEMBLED UNIT (with pad) 189.95

Pholo I: The author'ssurplus keyboard,mounted in its case withthe keyboard encoderROM circuit, repeat keyand LED monitor featuresdiscussed in this article.

Using a Keyboard ROM

Bob Brehm1095 Sherman AvMenlo Park CA 94025

The keyboard encoder read only memoryhas become more plentiful in the experi-menters' market recently. This versatiledevice can be used to generate the lull ASCIIcharacter set thus allowing the hobbyist toeasily and economically convert unencodedor non-ASCII keyboards to ASCII. Thisarticle presents both the logic theory and ageneral description of one such encoder, theSMC KR2376 MOS keyboard ROM, so you

will know how it works as well as thefeatures that are available. Addition of arepeat key and LED code readouts are alsoshown and explained. After reading this, youshould be able to take any keyboard, strip itof unknown encoding and convert it to anASCII keyboard for use with yourcomputer.

The SMC KR2376 is a 40 pin MOSkeyboard encoder read only memory with

Si

Photo 2: The keyboardencoder and related cir-cuitry is mounted on per-forated board on the backside of the keyboard as-sembly. The maze of wiresin this picture is the resultof creating the keyboardmatrix by hand wiring allcross points.

76

YO Yl Y2 Y3 Y4 Y5 Y6 Y7 YB Y9 YIO

PARITY OUTPUT £~J>

06 D5 D4 D3 02 Dl DO

DATA OUTPUTS TOMICROCOMPUTER

TYPICAL SWITCH CROSS POINT

* Rl (680 Kfl), CI (. 001 fit) PROVIDE 1.5 mS DELAY

**R2(IOOKni,C2 (50pF) PROVIDE 50 KHzCLOCK FREQUENCY

Figure I: The internal organization of a typical keyboard encoder ROM array. The ring counters are a logic design elementwhich generates a one of "n" output which changes each time a clock pulse is received. Thus, picking one of the 8 X outputrows with one ring counter, and listening to one of the II Y input columns through a comparator addressed by the other ringcounter, the device can select a unique cross point of the matrix. The ring counter outputs also address the ROM array, so thatstopping the clocks when a key is found depressed allows the ROM to decode the ASCII output for the key contact.

all the logic necessary to encode single polesingle throw keyboard switches into ASCIIcode. This integrated circuit featuresTTL/DTL or MOS compatible outputs, 2key rollover, N key lockout, self-containedoscillator, a delay network to eliminate theeffect of contact bounce, and static chargeprotection of all inputs and outputs! Inaddition external control is provided forselection of output polarity and even or oddparity generation. With prices ranging from$6 to $20, depending on source, all thesefeatures are quite a bargain.

The logic design of this ROM is easilyunderstood if you look at the internalstructure and outside world connectionsshown in figure 1.

The KR2376 contains a 2376 bit ROM,an 8 stage ring counter, an 11 stage ringcounter, an 11 bit comparator, an oscillatorcircuit, an externally controllable delay net-work for eliminating the effect of contactbounce, and output drivers compatible withTTL, DTL or MOS logic families.

The ROM portion of the chip is a 264 by9 bit memory arranged into three 88 word

If

r)| ;|j>;ryi

Hiiii

Photo 3: The LED monitor assembly is alsoconstructed on perforated board, thenmounted to the keyboard assembly. A cor-responding hole in the cabinet was cut sothat the LEDs are visible when the keyboardis being used (see photo I).

77

Table I: Mode Selection Logic.

Shift Key

Control Key

Mode

(pin

4)

(pin 5)

Normal

(N)

0

0

Shift

(S)

1

0

Control

(C)

0

1

Invalid

1

1

where:

0 = 0 volts input to the pin in question

1 = 5 volts input to the pin in question

Yo

Y1

Y2

Y3

Y4

Y5

Y6

Y7

Y8

Y9

Y10

SUBLFSUB

t

tt

EMHTEM

■K-*

'

<—

DC1

DC1DC1

S1S1S1

FSFFFS

DLENULDLE

ETBBELETB

NSC

NAKENQNAK

/?

NUL

>

NUL

'<

NUL

mMCR

nNSO

b

B

STX

V

VSYN

c

C

ETX

X

X

CAN

z

ZSUB

NSC

---,

^,

■v.

^,

\,

%

^

■-*,

{[

ESC

ULULUS

LFLFLF

P

P

DLE

\

ULULUL

CRCRCR

BSBS

BS

UNUN

UN

+++

NSC

8

(

NUL

9)EM

000

SUB

CR

}

GS

RS

\FS

DELDELDEL

VTVTVT

SYNACKSYN

NSC

—^»—

—i»_

-v

—:=»—

—:*—

*SUB

}]GS

NULNULNUL

DELDELDEL

+±±

STXSTXSTX

RSRSRS

ETXETXETX

SPSPSP

EOTEOTEOT

NSC

+ESC

1

LFF

kKVT

J

JLF

h

HBS

g

GBell

fFACK

d

D

EOT

s

S

DC3

a

A

SOH

FFFFFF

NSC

\,

^,

•v.

\,

\,

s,

\@

NUL

0

0SI

i1HT

u

U

NAK

y

YEM

t

T

DC4

r

R

DC2

e

E

ENQ

w

W

ETB

q

QDC1

@

NSC

^.

^»

—a.—

^

—i»—

%

"~.

^»

N

%

•-.

7ETB

6

&SYN

5

%

NAK

4

$

DC4

3

#DC3

2DC2

1!

DC1

{

t

ESC

DEL

ULUS

ESCESCESC

BSBSBS

NSC

^»—

^»

—^»—

i»—

>»

*•»

—^»—

N = NORMAL

S = SHIFT

C = CONTROL

Figure 2: Key switches hooked up to the author's keyboard encoder. Thischart shows the ASCII codes available in the KR2376 ST ROM, and thewiring of switches within the matrix in the author's case. An ASCII codechart (see figure 6) can be used to verify the switch wiring by looking at bitpatterns using the LED indicators described in figure 5.

by 9 bit groups. The appropriate level (+5 V)on the shift and control inputs select one ofthe three 88 word groups. Each of the 88individual words in a selected group areaddressed by the two ring counters. Con-sequently the ROM address is formed bycombining the shift and control inputs withthe two ring counters.

The external outputs of the 8 stage ringcounter and the 11 bit comparator are wiredto the keyboard to form an XY matrix withthe 88 (or less if full ASCII is not needed)keyboard switches as the cross points. In thestandby condition, when no key is de-pressed, the two ring counters are clockedand sequentially address both the ROM andthe key switch array. The absence of a dataready output indicates that the data outputsare not valid at this time. (They are actuallyall ones if positive logic is used, or all zerosif negative logic is selected.)

When a key is closed a single path iscompleted between one output of the 8stage ring counter (pins XO thru X7) and oneinput of the 11 bit comparator (pins YO thruY10). After a number of clock cycles, acondition will occur where a level on theselected path to the comparator matches alevel on the corresponding comparator inputfrom the 11 stage ring counter. When thisevent takes place, the comparator generatesa signal to the clock control and to the dataready output via the externally controlleddelay network. The clock control stops theclock to both the 8 and 11 bit ring countersand the data output bits (DO to D6) stabilize

Table 2: Some Control Codes. Most key-boards do not have enough keys to generateall 88 possible cross points of the matrixshown in figure 2. As a result, certain con-trol mode overlaps are used. The following isa table of the control functions which wereimplemented in the author's version of thekeyboard encoder. To get these ASCIIcodes, press the indicated letter or key andthe "CTRL" key simultaneously.

Key Combination

ASCII Code

Ctrl C

ETX

Ctrl B

STX

Ctrl +

ESC

Ctrl G

BEL

Ctrl D

EOT

Ctrl L

FF

Ctrl J

LF

Ctrl M

CR

Ctrl H

BS

78

OUTPUT TOKEYBOARD MATRIX

INPUT FROMKEYBOARD MATRIX

X2 X3 X4 X5 X6 X7 YO Yl Y2 Y3 Y4 Y5 Y6 Y7 Y8 Y9 YIO

40 |39 |3B |37 J36 |35 \l,4 \$3 \i2 |si |30 |29 |28 |27 \z6 |25 |24 |g3 |22 Igl

ICI

SMC KR2576

Rl

.' ,- IOOK50pF

^1

Q

PARITY

u u A A A A 6

D6 D5 D4 D3 D2 Dl DO

T

4

-I2V

DATA DATA

OUTPUTS ^EADY

CONTROL

* 5V

^7

CONTROL(KEYBOARD)+ 5V-^o *

SHIFT ( KEYBOARD)

S2

DATA _NEG JINVERT 2

-, POS

"2 o— 1

S80K J,+5V

")f-

!H*

C2.001

Figure 3: Specific wiring diagram for the keyboard encoder. This diagram shows the major partof a parallel keyboard interface, the encoder itself.

with the ASCII code of the depressed key.When DO to D6 are stable a valid signal isindicated on the data ready output pin. Thedata outputs remain stable until the key isreleased.

An additional feature provides for ex-ternal polarity control of the data outputs.Parity invert provides polarity control of theparity output while the data (and dataready) invert input provides for polaritycontrol of the data outputs D0-D6 and thedata ready output. Both of these features arevery useful depending upon your computerrequirements for odd or even parity andpositive or negative data outputs.

The above general description shouldprovide you with enough knowledge tounderstand a practical implementation ofthe read only memory in a typical surpluskeyboard. The trick is to remove the originalencoder and to wire up the new, docu-mented encoder, using figure I as a model.

Implementation

The keyboard described is an "UltronicVideomatic 7000" which was purchasedfrom John Meshna for about $35. While Iused this specific surplus board, any key-board which uses SPST switches can beadapted to a new encoder. Do not attempt

to use "Hall effect," capacitive sensing orother "no switch" keyboards with thismethod. This keyboard has a nice metallicenclosure which helps shield the read onlymemory and its associated circuitry fromnoise. The diode board that came with theunit was discarded to make room for theROM board and the LED monitoringreadouts.

My keyboard had all switches soldered toa circuit board with one side of each switchcommon to ground. It was necessary tobreak the foil pattern and hook the switchesup in a manner consistent with the ROMrequirements. Many newer keyboards al-ready have their switches wired properly forthis ROM and need not be changed. The XYmatrix wiring chart for the full ASCIIcharacter set is shown in figure 2. To wireyour own keyboard, connect one side of allswitches of each Yj column together; eg: forY4 I connected together one side of theswitches for M, =, H, Y, #. The other side ofthe switches go to the Xj row buses which goto the appropriate pins on the ROM.

Each Xj and Yj switch can generate threedifferent codes depending upon the voltagespresent on the STROBE (S) and CONTROL(C) inputs. Mode selection logic is shown intable 1.

79

As can be seen from figure 2 there existseveral redundant keys whose codes may begenerated by enabling the control code ofother keys. This characteristic is very usefulif you don't have a full 88 key keyboard(the usual case). Actual keys implementedon my keyboard are shown as small switchesin figure 2. Several of these keys and theircontrol functions are shown in table 2.

The pin diagram of the KR2376 is shownin figure 3 along with the circuitry tocontrol the "function pins" of the ROM inaddition to the delay and oscillator com-ponents. On my keyboard the parity selectand data invert switches are placed on therear of the enclosure.

So far we have shown how to hook upthe switches on the keyboard to the ROMand provide selectable parity and data out-put. It is now time to describe severaladditional features that enhance the opera-tion and use of the keyboard in the personalcomputer system.

Circuit Enhancements

You can enhance the usefulness of yourkeyboard with the addition of a repeat key,selectable strobe output circuitry and anLED code readout circuit. Each of these

improvements makes your keyboard moreversatile and allows it to be connected tocomputers with varying input requirements.

Repeat Function

The basic idea behind the repeat functionis to pulse the data ready signal while theASCII outputs remain stable. Since thecomputer reads a keyboard input every timethe data ready line changes from its steadystate, the computer will accept the samecharacter many times if we pulse this signal.An easy and economical way to implementthis function is to use a 555 timer and a7400 NAND gate as shown in figure 4. Thetimer operates at approximately 10 Hz or 10characters per second. Closure of the repeatswitch allows IC3b output to change at a 10Hz rate. The ROM data ready output is aconstant +5 V (using positive logic) when akey is depressed. Therefore the data ready(IC3c output) is gated at a 10 Hz rate whenthe repeat switch is closed. Since we haveonly used three gates of the 7400 we can usethe remaining gate to implement a dataready invert function useful if a positivegoing strobe is required with positive logic.Additional combinations can be made withnegative logic. To use the repeat function

DATA READY.rPINI6 OF LROM

(POSITIVE LOGIC)

9 l(I IC3C I

^r

IC3 ■ 7400PIN 14 - + 5VPIN 7- GND

IC2555

")f

C4I

4,8

R4470K

• R5I470K

+ 5VJ

■ C3' IDISC

NOTE-DATA READY OUTPUTSSHOWN FOR POSITIVE LOGIC

S3 DATA READY POLARITY SELECT

N> < I DATA READY

Figure 4: Adding a repeat key. The logic required to add a "repeat" function to the keyboardconsists of a 555 oscillator and gating under the control of the repeat key switch. This circuitalso provides for either normal or inverted forms of the data ready line output. A key is"repeated" by making the normal steady state output of the keyboard encoder's data ready lineoscillate at about a 10 Hz rate.

80

Dl O-

DZ\Z>-

03 O-

FROM DATAOUTPUTS

04 \Z>-

D5C>—

06 O-

parityQ>-

POWER CONNECTIONS

IC TYPE + 5V GND

IC4 7400 14 7

IC5 7400 14 7

ri—V

l 2 IC4a b^

2 IC4d lo-IC5o \>-

HI IC5c lO-

-<i lC5d Y>—

LED 0

N

LEO 20-—-

LED 3

-©=

.ED 5

/

/

'■&

R6

I50H (8)1/4 W-AM

R7—W^-

R8

-Wr

R9

RIO—VW-

Rll

-vw-

RI2—"WV-

/* RI3

WAr-

Figure 5: Keyboard monitor LED display circuit. Adding two 7400 NANDpackages, 8 resistorsand 8 LED indicators provides an invaluable debugging tool for checking out the keyboardmatrix wiring — and a fascinating display once the wiring is pronounced error free. Check outeach key in normal, shifted and control modes using the standard ASCII code chart of figure 6.

just press the desired alphanumeric key andthen the repeal key until the desired numberof letters are transmitted.

LED Code Display

This option is by no means necessary butis very useful to check out the operation ofthe keyboard as well as have a ready sourcefor determining the ASCII code of anykeyboard character. The circuit diagram isshown in figure 5.

When any input to the 7400 NAND gategoes high it forces the output low whichgrounds the LED causing it to light. Duringstandby using positive logic all inputs will behigh and consequently all LEDs will be lit.Negative logic will cause them to be extin-guished in standby. The LEDs are arrangedon the keyboard such that the rightmostLED represents the least significant bit (DO)and the leftmost LED represents the paritybit. Using positive logic the ASCII code forany depressed key will be shown on theLEDs as a lit LED for a 1 and a dark LEDfor a 0. The opposite is true for negativelogic. It is very interesting to watch theparity bit change as the code changes. Witheven parity you should always have an even

number of LEDs lit and with odd parity anodd number should be lit.

Final Checkout

Final checkout should determine whetherthe proper ASCII code is present on theLEDs (thus the output), whether the shift,control, parity select, data ready select, anddata invert options function properly, andwhether the repeat function actually pulsesthe strobe signal.

Code checkout is easy if you refer tothe ASCII code chart given in figure 6. Allkeys that you have implemented shouldshow their codes on the LEDs. (In the eventyou didn't install the LED readouts, avoltmeter at every bit will show the logiclevels. Individual bit measuring for 264codes is very tedious and since the cost ofthe LED readout unit is only about $3 it ishighly recommended that this feature bebuilt for test purposes if not actually in-stalled.) Try all keys in the normal (lowercase ASCII letters and numbers), shift(upper case ASCII and shift characters) andthe control mode. Press each key severaltimes to make sure the code is repeated onthe LEDs. In my case I found that for

81

Figure 6: USA Standard for Information Exchange (ASCII), code chart. The physicalarrangement of key tops on your particular keyboard switch array may vary, but thecorrespondence between a given code and a given graphic symbol should follow this chart forASCII character exchange purposes.

T

HexF

ypi8 biadecorm

:al

t

imal

at

7

1 1_

6 5 4

i i i

3 2 10

0

HIGHRDER

1

LOW

ORDER

0

~""""~\^^ High Order Bits 6,5,4

000

001

010

011

100

101

110

111

Low Order Bits "^

~^^^^ Hex 1

HexO^---^^

0

1

2

3

4

5

6

7

3

2

1

0

0

0

0

0

0

NUL

DLE

SP

0

@

P

P

0

0

0

1

1

SOH

DC1

"!*■

1

A

Q

a

q

0

0

1

0

2

STX

DC2

■•

2

B

R

b

r

0

0

1

1

3

ETX

DC3

#

3

C

S

c

s

0

1

0

0

4

EOT

DC4

$

4

D

T

d

t

0

1

0

1

5

ENQ

NAK

%

5

E

U

e

u

0

1

1

0

6

ACK

SYN

&

6

F

V

f

V

0

1

1

1

7

BEL

ETB

•

7

G

w

g

w

0

0

0

8

BS

CAN

(

8

H

X

h

X

0

0

1

9

HT

EM

)

9

I

Y

i

V

0

1

0

A

LF

SUB

J

z

i

2

0

1

1

B

VT

ESC

+

K

[

k

{

1

0

0

C

FF

FS

,

<

L

\

I

I

I

1

0

1

D

CR

GS

-

=

(VI

]

m

}

1

1

0

E

SO

RS

>

N

1

n

1

1

1

F

SI

US

.

/

I

?

O

-

0

DEL

The following table gives expansions of the multiple letter mnemonic functions in the chart.

Bit 7 is ignored in 8 bitprocessors.

NUL

Null

VT

Vertical Tab

SYN

SYNchronous idle

SOH

Start Of Heading

FF

Form Feed

ETB

End Transmission Block

SIX

Start of TeXt

CR

Carriage Return

CAN

CANcel

EIX

End of TeXt

SO

Shift Out

EM

End of Medium

bOI

End Of Transmission

SI

Shift In

SUB

SUBstitute

ENQ

ENQuiry

DLE

Data Link Escape

ESC

ESCape

ACK

ACKnowledge

DC1

1

FS

File Separator

BEL

BELI

DC2

( Peripheral

GS

Group Separator

BS

Back Space

DC3

I control

RS

Record Separator

HT

Horizontal Tab

DC4

)

US

Unit Separator

LF

Line Feed

NAKSP

Negative AcKnowledgeSpace

DEL

DELete (rubout)

certain letters I would get multiple codes.This problem was traced to having several Xjlines hooked together or Yj lines hookedtogether. After correcting these errors thekeyboard functioned properly. Voltagesshould not exceed +5 V for input on pin Ior -12 V on pin 18 of the ROM. Totalpower consumption is 200 mW for theROM, 265 mW for the TTL ICs, and1333 mW for the LEDs.

Interfacing the keyboard to your com-puter should be easy if a parallel input portis available. Simply connect the DO to D6inputs, the parity line and the data readyline to the input port using the appropriatelogic level as required by your computer.

If you have a serial input port available

for your keyboard, a parallel to serial con-verter is necessary. You can use half of aUART as discussed in Don Lancaster's excel-lent article "Serial Interface" in the Septem-ber 1975 issue of BYTE [page 22]. Thisstrategy, however, leaves half of the UARTunused. A more reasonable approach forserial interface is to use the Teletype trans-mitter circuit which is described in full detailin Don Lancaster's TTL Cookbook pub-lished by Howard W Sams, Indianapolis IN,and available from BITS Inc.

Building an ASCII encoded keyboardusing the KR2376 ROM is easy and eco-nomical, and, in addition, provides a fullcharacter set usually found only in expensivekeyboard logic assemblies."

82

Your microcomputer is only as good

as its memory

£>#■

„ •> .„.6 DISK ' MEMO* •

Your m icro-computer is...in a mannerof speaking...capable of think-ing. The amount

of information you can store, combinedwith the access speed, determines thebottom line capability of your microcomputer.

The Midwest Scientific Instruments' FD-8 FloppyDisk Memory System will enable you to get themost out of your microcomputer. . .6800 or 8080.We have the most complete 6800 disk operatingsystem available today, which interfaces to anymicrocomputer via a single PIA chip.

When used with the MSI FDOS OperatingSystem.. .included with purchase. . .the FD-8gives your microcomputer a level of performancewhich can only be matched by larger computers.

You can have program save and load withnamed, variable length, password protectedfiles at three levels: object code files, source codefiles, and BASIC files.

It has disk routines which can be used easily by

I muni MBI

g-jUl 6800 S9-T- I-"""

low level assembler lan-guage programs as well ashigh level BASIC programs.The coresident assem-bler/editor saves and loadssource files from disk,assembles and stores objectcode on disk, and creates assemblylistings on a high speed printer.You get a full ANSI standard BASIC inter-preter* with program load and save, from disk aswell as tape, with both random and sequentialdisk data files. BASIC also has multi-l/O portcapability under software control.

And all you need do to access any of thesefunctions is type the appropriate commands onyour terminal.The FD-8 is complete, including all power sup-plies, cabinet, cables, software, manuals, anddocumentation.

You can order the FD-8 as a kit for $1,150.00,or wired and tested for $1,395.00.

Visit one of our dealers for a demonstration,or send for our free Catalog of MSI products.

American MicroprocessorsEquipment & Supply Corp.Chicagoland Airport, P.O. Box 515Prairie View, Illinois 60069(312)634-0076

Microcomputer Systems, Inc.144 South Dale Mabry AvenueTampa, Florida 33609(813) 879-4301

Micro Store

634 South Central ExpresswayRichardson, Texas 75080(214) 231-1096

Vanguard Systems Corporation6812 San PedroSan Antonio, Texas 78216(512) 828-0553

A-Vid Electronics Company1655 East 28th StreetLong Beach, California 90806(213) 426-5526

Electronics for Yachting1525 South East 16th StreetFt. Lauderdale, Florida 33316(305) 525-3478TWX 510-955-9484

High Technology1020 West Wilshire Blvd.Oklahoma City, Oklahoma 73116(405) 842-2021

Computer Workshop174 Ifield RoadLondon EnglandSW10 9AG01-373-8571

MSI is a dealer for Southwest Technical Prod220 West Cedar • Olathe, Kansas 66061

THicUvett Scientific

f)K4t>lU(KeHt6

220 West Cedar • Olathe, Kansas 66061 • 913/764-3273TWX 910 749 6403 (MSI OLAT)

nnnnnnnnnnnnnnnnnnnDDDDDn

□ Before I forget. . .send me your catalog □

n Name □

□ O

□ Address p

□ □

a Citv □

D State Zip □

D BY577 Ll

DDDnnnnnnnnnnnnnDDDDDDDDn

*MSI BASIC is an additional $65.00

ucts • Mastercharge & BankAmericard Orders accepted• 913/764-3273 • TWX 910 749 6403 (MSI OLAT)

Implementing

Jack Emmerichs8465 N 51st

Brown Deer Wl 53223

the TinyAssembler

Listing 1: The external address table. This series of jumps is the sole interfaceto the outside world from Tiny Assembler 6800. As originally written,terminal oriented 10 is done with these five external references to MIKBUG,Motorola's Monitor Program.

EXTtHNAL AunHESS TAOLE

( U 790}

7E

El

1)1

CHHOUT

JMP

4E1U1

(0793!

7E

El

AC

CHHIN

JMP

SE1AC

(1)796)

J6

heaout

PSHA

(0797)

HO

Ell

67

JSP.

iE067

(079A)

J2

PULA

<079B)

7E

EO

6B

JMP

SE06P,

(079t)

7E

Ell

CC

BLMIUT

JMP

*E0CC

(07A1)

7t

EO

7E

STHOUt

JMP

S.E07E

Notes on External Linkages

If MIKBUG is used (for example, in a Southwest TechnicalProducts machine, or an expanded version of one of Motorola'sdevelopment board kits) then this code should be used as is. If youinterface to your own custom monitor, this code must be replacedby references to equivalent routines as follows:

CHROUT: The contents of the accumulator, treated as an ASCII

character, are dumped on the output device.CHRIN: The contents of the accumulator are defined by an

ASCII code obtained from the input device.HEXOUT: The contents of accumulator A are dumped to the

output device as two hexadecimal encoded ASCII digits.BLKOUT: A blank is dumped on the output device.STROUT: A string, terminated by an EOT (hexadecimal 04) code

is dumped on the output device. The index register points to

the string on entry, and is updated during the operation.

When all the functional requirements forTiny Assembler had been described in a wellstructured format, the final structural net-work of the program was realized, as given atthe end of last month's introduction to thisprogram. Combining figure 3 of page 66,April 1977 BYTE, with detailed tabledefinitions, I was at long last ready to beginactual coding of the assembler itself.

Coding the Program

I was immediately confronted with twoproblems. First, I did not yet have anassembler to work with. Second, I had noM6800 machine available! I therefore de-cided to start by writing a cross assembler inPL/I. This would let me find and correctany logical bugs in the assembler's design. Itwould also provide an assembler capable ofproducing the final M6800 version of thedeveloped program.

Because structured design techniques arelanguage independent, no redesign wasnecessary for the development of the crossassembler. (In fact, assemblers written in8080 or Z-80 code could be developed justas easily.) During testing of this program,several minor logical errors were corrected,and an operational design was availablefor the final version of the program. In a veryreal sense, the assembler was used to writeand debug itself.

The next step was to translate eachfunction from the PL/I code to M6800assembler code. As each block of code wasdeveloped, it was added to existing functionsand run through the cross assembler to catchany errors and to find the length of thegenerated code. Final debugging of eachfunction had to be postponed until a ma-chine was available. The code was basicallydeveloped in a top down manner startingwith the mainline and working down thehierarchy of functions. However, the orderof listing different parts of the program was

84

M6800 Structured Code

Conventions

General Structure

M6800 Implementation

IF

F (test condition) THEN

IF

TST

CONDITION

THEN

(then processing)

BNE

ELSE

ELSE

ELSE

** *

| then processing

(else processing)

* * *

ENDIF

BRA

ENDIF

ELSE

* * -x-

I else processing

* * #

ENDIF

* * *

1 continue

** *

set initial cond)

* SET INITIAL COND

DO WHILE (condition)

DO

TST

CONDITION

DO

(do group)

BNE

ENDDO

WHILE

(may change cond)

#* *

/ do group processing

ENDDO

** *

** *

BRA

DO

ENDDO

* * *

■X- * *

set initial cond)

* SET INITIAL COND

00 UNTIL (condition)

DO

■X- -X- *

)

DO

(do group)

* # *

> do group processing

UNTIL

(may change cond)

* * *

)

ENDDO

ENDDO

TST

BNE

* * *

* * #

CONDITIONDO

JSR

SELECT

I

\ general case structure:

JMP

ENDSELECT

SELECT

LDX

#CASETABL

LOOP

JSR

NXTCASE Calculate condition

SELECT (based on case)

TST

CONDITION

CASE (condition 1)

BEQ

EXECUTE

(process 1)

INX

CASE (condition 2)

INX

(process 2)

BRA

LOOP Move to next CASE

CASE (condition 3)(process 3)

EXECUTE

JSR

X Execute CASE

RTS

Return from select

ENDSELECT

*

CASETBL

BRA

CASE1 \

CASE2 } Table of CASE Conditi

CASE3 J

"he case structure, recoded using

BRA

ons

he DO UNTIL to check case:

BRA

CASE

*

SELECT

(point to first case)

CASE1

* * #

* * *

> First CASE procedure

DO UNTIL (selected condition)

CASE2

RTS

J

(advance to next case)ENDDO

* * #

> Second CASE procedure

(execute case pointed to)

RTS

;

ENDSELECT

CASE3ENDSELECT

* * *RTS

* * *#* *

**#

\ Third CASE procedure\ continue

Table 1: The general programming structures shown in the table above have been implemented as shown in the right handcolumn where *** represents the particular code which is executed within these control structures.

influenced by the one pass design of theassembler. All data declarations, output text,tables, and commonly called subroutineswere placed at the front of the listing toreduce the number of forward references.The program mainline follows the sectioncontaining common subroutines.

While the M6800 has a very powerfulinstruction set, it cannot directly supportthe functions shown in the pseudocode used

in the listings given as examples. Therefore,control functions such as DO, THEN, ELSE,UNTIL, WHILE and CASE need to beperformed by in line routines of M6800instructions. Table 1 shows some of thecommon functional structures with theirassociated assembly language routines. Thebasic structures of these in line routines will

Text continued on page 92

85

Table 2: Hexadecimal object code. This table contains the complete object code of TinyAssembler 6800, assembled at an origin of 0000 hexadecimal in memory address space. Thisversion can be used if necessary to load Tiny Assembler 6800 by hand. This type was set bymachine from the same data which was used to create the bar code listings of figure 7. Note,however, that to make this version readable, fixed length lines were used (as opposed to variablelength lines in figure I).

Address

1

Data

000(1

7E

07

A4

00

20

00

00

00

00

20

20

20

00

00

00

00

0010

00

00

2A

20

20

20

00

OD

00

04

00

OD

00

00

00

00

0020

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00.10

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

0040

5 8

20

20

20

OD

00

00

2A

2A

2A

20

45

52

52

4F

52

0050

20

2D

20

00

OA

00

00

20

04

OD

OA

OA

OA

OA

00

00

0060

4C

4F

43

4E

20

42

31

20

42

32

20

42

33

20

OA

OA

00 7 0

00

00

04

OD

00

00

12

04

OD

OA

OA

OA

00

00

2A

2A

0080

2A

20

^^

4E

52

45

5 3

4F

4C

5 6

45

44

20

49

54

45

0090

4D

5 3

3 A

OD

OA

00

00

04

OD

OA

00

00

2A

2A

2A

20

' 00A0

5 3

59

4D

42

4F

4C

53

2C

20

53

4F

52

54

3F

OD

OA

oo no

OA

00

04

00

00

20

20

20

00

00

00

00

00

00

00

00

ooco

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

001)0

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

ooi;o

oo

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

001-0

00

00

06

06

1 1

17

08

IF

04

23

03

26

03

00

00

00

0 100

00

29

03

2C

02

00

00

2E

04

00

00

32

02

34

02

36

0 110

02

00

00

38

0 5

3D

OA

47

07

00

00

00

00

4E

01

00

0 1 20

00

00

00

00

00

42

41

IB

50

44

43

89

10

44

44

8B

0 1 JO

10

4F

44

84

10

5 3

4C

48

30

53

5 2

47

30

43

43

24

0140

40

43

53

25

40

45

5 1

27

40

47

45

2C

40

47

54

2E

015 0

40

48

49

22

40

49

54

85

10

4C

4 5

2F

40

4C

53

23

0 1 60

40

4C

54

2D

40

4D

49

2B

40

4E

45

26

40

50

4C

2A

0170

40

5 2

4 1

20

40

53

52

8D

40

5 6

43

28

40

56

5 3

29

0 180

40

42

41

I |

50

4C

43

OC

50

4C

49

OE

50

4C

52

4F

0 10 0

JO

4C

5 6

OA

50

4D

50

81

10

4F

4D

43

30

50

58

8C

0 1 AO

1 1

41

41

19

50

45

43

4 A

30

4 5

5 3

34

50

45

5 8

09

o i no

50

4E

44

00

EO

41-

5 2

88

10

51

55

00

FO

43

42

01

0 1 CO

FO

43

43

02

FO

44

42

03

FO

4E

43

4C

30

4E

53

31

oi no

50

4F.

58

08

50

4D

5D

4E

3 I

53

52

8D

31

44

41

86

0 1 to

10

44

5 3

8E

1 1

44

5 8

CE

1 1

53

5 2

44

30

45

47

40

0 1 10

30

4F

50

01

50

52

4 1

8A

10

52

47

04

FO

53

48

36

0200

00

5 5

4C

3 2

00

4D

42

05

FO

4F

4C

49

30

4F

52

46

02 10

30

54

49

3B

50

54

5 3

39

50

42

41

10

50

42

43

82

0220

10

4 5

43

OD

50

45

49

OF

50

45

56

OB

50

54

41

87

02 JO

20

54

5 3

8F

21

54

58

CF

21

55

42

80

10

57

49

3F

0240

50

41

42

16

50

41

50

06

50

42

41

17

50

50

41

07

0250

50

5 3

54

4D

30

53

58

30

50

58

5 3

35

50

41

49

3E

0260

50

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

0270

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

0280

00

00

00

00

00

00

00

00

00

00

oo

00

00

00

00

00

0290

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

0 7A0

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

0 2 BO

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

0 2C0

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

02 DO

00

00

00

00

00

00

00

00

00

00

00

00

00

00

01

01

0 21:0

01

01

39

00

00

00

00

00

00

00

00

00

00

00

00

00

07 KO

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

0710

7E

El

Dl

7E

El

AC

36

BD

EO

67

32

7E

EO

6B

7E

EO

07A0

CC

7E

EO

7E

BD

02

Dl

CE

02

61

6F

00

08

8C

07

8F

071)0

26

F8

86

39

B7

02

Dl:

CE

00

B8

DF

2A

7F

00

1C

7F

07CO

00

31

CE

07

B7

FF

AO

48

8E

AO

7F

CE

00

59

DD

07

0 7 DO

A!

mi

09

2 A

BD

OF

5A

7E

EO

E3

CE

00

B8

86

3E

BD

071-10

07

90

BD

07

93

81

21

26

08

8C

00

B8

27

F4

09

20

0 7F0

Fl

A7

00

91

IB

26

01

39

8C

00

FO

27

E5

81

20

2B

0800

El

81

5F

22

DD

08

20

DA

DF

24

DE

2A

96

17

91

IB

0810

26

14

7D

00

31

27

03

BD

08

B2

86

01

97

31

BD

07

0820

DA

CE

00

B8

DF

2A

A6

00

97

17

08

DF

2A

DE

24

39

08J0

96

17

91

OA

27

01

39

BD

08

08

20

F6

Dl-

OA

DF

05

0840

DF

07

CE

00

05

D6

17

Dl

OA

27

ID

Dl

IB

27

19

CI

0850

2B

27

15

CI

2D

27

I 1

CI

2C

27

OD

E7

00

8C

00

08

0860

27

01

08

111)

08

08

20

DD

39

97

53

DF

20

CE

00

44

08 70

BD

07

Al

DE

20

7C

00

03

39

7D

00

03

23

01

39

96

0880

16

D6

31

CI

01

27

19

CI

02

26

07

97

B6

7C

00

31

0890

20

IA

CI

03

26

07

97

B7

7C

00

31

20

OF

DD

08

B2

O8A0

DE

2F

Dl

B3

96

16

97

B5

86

02

97

31

DE

2F

08

DF

0 8 BO

2F

39

DF

24

CE

00

73

BD

07

A!

CE

75

30

6D

00

09

08C0

26

FB

86

01

BD

07

90

96

B3

BD

07

96

96

B4.

BD

07

0 8 DO

96

C6

01

CE

00

B5

Dl

31

2B

17

26

OA

86

01

111)

07

08E0

90

86

14

BD

07

90

ni)

07

9E

BD

07

9E

BD

07

9E

20

08F0

08

BD

07

9E

A6

00

BD

07

96

08

5C

CI

04

26

D7

96

0900

31

81

04

26

OA

86

01

BD

07

90

86

14

HI)

07

90

BD

09 10

07

9E

DE

2F

DF

BJ

DE

24

86

OA

III)

07

90

96

OA

97

0920

B5

97

B6

97

B7

86

01

97

31

39

CE

00

04

D6

OA

7F

09JO

00

03

7F

00

3F

E7

00

08

8C

00

OA

26

F8

96

IB

97

0940

17

BD

08

08

91

IB

27

E2

81

2A

27

DE

91

OA

27

09

09 Ml

BD

08

3C

7C

00

26

BD

OD

IB

BD

08

30

91

IB

27

3D

0960

BD

08

3C

86

02

97

19

BD

09

DD

86

04

97

19

7D

00

09 70

03

22

B7

96

18

81

OE

26

04

BD

08

1)2

39

D6

2E

81

09 8 0

OF

26

05

BD

OE

DB

20

15

BD

08

30

81

23

26

05

97

0990

04

BD

08

08

BD

08

30

BD

09

A3

BD

OA

CA

BD

OE

15

0 9 At)

7E

09

2A

Dl

2A

96

17

81

58

26

IE

A 6

00

91

OA

27

09 BO

OE

91

IB

27

OA

8 1

2B

27

06

81

2D

27

02

20

OA

86

O9C0

58

97

04

86

30

97

17

20

1 3

A6

00

08

91

OA

27

OC

0 9 DO

91

IB

27

08

8 1

2C

26

Fl

A6

00

97

04

39

96

05

81

09F0

41

2C

06

86

41

BD

08

69

39

81

5A

2F

06

86

41

BD

09i 0

08

69

39

84

IF

4A

48

CE

00

Fl

4D

27

04

08

4A

20

0A0 0

F9

E6

01

D7

29

E6

00

4F

5 8

49

58

49

CE

01

25

DF

OA 1 0

3D

DB

3E

99

3D

D7

3E

97

3D

CE

00

06

DF

32

7D

00

OA2 0

29

26

06

86

42

BD

08

69

39

DE

3D

DF

34

BD

OA

A5

0A3 0

7D

00

1 1

23

09

BD

OA

4E

7D

00

1 I

23

01

39

08

08

0A4O

08

08

DF

3D

CE

00

06

DF

32

7A

00

29

20

DO

A6

02

Address

0A5 0

97

2E

A6

03

16

C4

OF

D7

ID

44

44

44

44

97

18

D6

OA6 0

08

Dl

OA

26

OB

7D

00

ID

22

3A

81

02

23

33

20

34

0A7 0

81

03

22

2D

7D

00

ID

22

28

CI

41

27

19

CI

42

26

0A80

20

D6

2E

-ID

26

06

CB

01

D7

2E

20

OA

81

03

27

02

OA90

CB

30

CB

10

D7

2E

4C

85

02

26

09

86

05

97

18

20

OAAO

03

7F

00

1 1

39

36

DF

20

9F

38

7F

00

1 1

96

19

97

OABO

3C

DE

32

9E

34

34

32

Al

00

26

09

08

7A

00

3C

26

OACO

F5

7C

00

1 1

Dl:

20

9E

38

32

39

96

18

D6

2E

81

03

OADO

23

OF

D7

16

BD

08

79

96

18

81

04

26

03

BD

OB

05

OAEO

39

96

04

81

23

26

04

BD

OB

4F

39

81

58

26

06

CB

OAI-0

20

BD

OB

8B

39

91

OA

26

06

CB

10

BD

OB

9D

39

86

OBOO

44

BD

08

69

39

BD

OB

D5

7D

00

3F

23

08

96

OD

97

OBIO

16

BD

08

79

39

CE

00

2F

96

OC

D6

OD

EO

01

A2

00

OB20

CO

01

92

2C

D7

16

BD

OB

2F

01

01

BD

08

79

39

91

0B30

2C

27

06

81

FF

27

02

20

04

98

16

2A

1 1

86

47

BD

0B4 0

08

69

DE

2F

7D

oo

IE

22

01

09

DF

2F

DF

B3

3 9

96

0B50

18

81

01

27

06

86

43

DD

08

69

39

37

BD

OB

D5

33

0B60

D7

16

BD

08

79

96

05

81

27

27

04

BD

OB

77

39

96

0B70

06

97

16

Dl)

08

79

39

7D

00

ID

23

07

96

OC

97

16

0B80

BD

08

79

96

OD

97

16

BD

08

79

39

37

BD

OB

D5

33

0B90

D7

16

BD

08

79

96

OD

97

16

BD

08

79

39

37

BD

OB

OBAO

D5

33

7F

00

3C

7D

00

OC

26

OD

7D

00

3F

22

08

96

OBBO

18

81

03

27

02

20

05

CB

20

7C

00

3C

D7

16

DD

08

OBCO

79

7D

00

3C

27

07

D6

OC

D7

16

BD

08

79

D6

OD

D7

OBDO

16

BD

08

79

39

7F

00

26

BD

OC

2D

BD

OC

IA

96

17

OBEO

81

2B

27

05

81

2D

27

01

39

97

09

DE

OC

DF

OE

BD

OBFO

08

08

BD

OC

2D

BD

OC

IA

96

09

81

2B

27

OE

96

OF

OCOO

90

OD

97

OD

96

OE

92

OC

97

OC

20

D2

96

OF

9B

OD

0C10

97

OD

96

OE

99

OC

97

OC

20

C4

7D

00

03

22

OD

7D

0C20

00

IF

22

08

7D

00

10

23

03

BD

OD

IB

39

7C

00

10

OCJO

7C

00

IF

7F

00

OC

7F

00

OD

96

17

81

24

26

OA

BD

0C40

08

08

BD

08

3C

BD

OC

DD

39

7F

00

IF

81

26

26

03

0C5 0

BD

08

08

Dl)

08

3C

CE

00

05

A6

00

91

OA

27

08

81

0C60

30

2B

3D

81

39

22

39

91

OA

27

31

8C

00

09

27

2C

0C70

8 5

30

26

06

86

4 A

BD

08

69

39

84

OF

A7

00

C6

09

0C80

D7

3C

D6

OD

96

OC

DB

OD

99

OC

7A

00

3C

26

F7

EB

0C90

00

99

2C

D7

OD

97

OC

08

A6

00

20

CB

7F

00

10

39

OCAO

CE

00

40

DF

32

CE

00

05

DF

34

BD

OA

A5

7D

00

1 1

OCBO

23

OA

DE

2C

DF

05

DF

07

7F

00

10

39

CE

00

12

DF

OCCO

32

CE

00

05

DF

34

BD

OA

A5

7D

00

1 1

23

OE

Dl:

2F

OCDO

96

18

81

04

26

01

09

DF

OC

7F

00

10

39

CE

00

05

OCEO

A6

00

91

OA

27

34

8C

00

09

27

2F

81

30

2B

06

81

OCFO

46

22

02

20

06

86

4A

BD

08

69

39

81

41

2B

02

8B

ODOO

09

84

OF

A7

00

96

OC

D6

OD

58

49

58

49

58

49

58

ODIO

49

EB

00

D7

OD

97

OC

08

20

C6

39

96

05

81

27

26

01)20

01

39

81

40

22

06

86

4B

BD

08

69

39

CE

02

DF

C6

0D30

01

CI

C9

26

06

86

45

Dl)

08

69

39

Dl-

34

DF

3A

CE

0D40

00

05

DF

32

BD

OA

A5

7D

00

1 1

23

2C

DE

3A

7D

00

0D50

26

22

OC

EE

04

DF

OC

9C

2C

26

03

BD

OD

B3

39

EE

0D60

04

9C

2C

27

06

86

46

BD

08

69

39

BD

OD

95

7C

00

0D70

IE

DE

3A

EE

04

DF

OC

39

DE

3A

6D

00

26

OC

BD

OD

0D8O

95

7D

00

26

22

03

BD

OD

B3

39

DE

3A

08

08

08

08

OD90

08

08

5C

20

9C

DE

3A

9F

38

9E

05

AF

00

9E

07

AF

ODAO

02

7D

00

26

23

06

9E

2F

AF

04

DF

27

EE

04

DF

OC

ODBO

9E

38

39

86

01

7F

00

3C

CE

02

61

81

19

2F

06

86

ODCO

49

BD

08

69

39

81

19

26

08

86

48

DD

08

69

7F

00

ODDO

03

E6

00

26

06

E6

01

26

02

20

OE

4C

08

08

08

08

ODEO

08

D6

3C

CB

05

D7

3C

20

D2

96

04

81

58

26

02

6A

ODFO

04

81

23

26

07

7D

00

ID

22

02

6A

04

96

18

81

04

OEOO

26

02

6C

04

9F

38

9E

3A

AF

00

9E

2F

31

AF

02

9E

0E10

38

7C

00

3F

39

7D

00

IE

22

01

39

86

01

CE

02

61

0E20

DF

22

7D

00

03

22

07

81

19

2F

04

7F

00

IE

39

36

0E3 0

7D

00

1C

23

05

1)1)

OE

A9

20

61

DE

22

A6

00

E6

01

0E4O

91

27

26

57

Dl

28

26

53

DE

2F

DF

36

BD

08

B2

DE

0E50

22

EE

02

DF

2F

DE

22

6D

04

2B

OB

26

14

DE

27

E6

0E60

04

D7

16

BD

08

79

DE

27

E6

05

D7

16

BD

08

79

20

0E70

IA

DE

27

A6

04

E6

05

CE

00

2F

EO

01

A2

00

DE

2F

0E80

09

DF

2F

D7

16

BD

OB

2F

BD

08

79

DE

36

Dl-

2F

DE

OE90

22

6F

00

6F

01

6F

02

6F

03

6F

04

Dl

22

08

08

OS

OEAO

08

08

DF

22

32

4C

7E

OE

22

DE

22

E6

00

26

05

E6

OEBO

01

26

01

39

EE

00

86

04

97

3C

A6

00

DD

07

90

08

OECO

7A

00

2C

26

F5

BD

07

9E

Dl:

22

A6

02

BD

07

96

A6

OEDO

03

DD

07

96

CE

00

93

BD

07

Al

39

CE

OF

4E

5D

27

OEEO

05

08

08

5A

20

F8

BD

08

30

AD

00

39

BD

OB

D5

9F

OEFO

38

9E

OC

DE

27

AF

04

9F

B3

9E

38

39

7F

00

ID

20

OFOO

06

7F

00

ID

7C

00

ID

BD

OB

D5

DD

OB

77

96

17

81

OF 10

2C

27

01

39

BD

08

08

20

EE

BD

OB

D5

96

OD

97

3C

0F2O

26

01

39

BD

08

08

97

16

BD

08

79

7A

00

3C

20

FO

0F3O

BD

OB

D5

DE

OC

DF

2F

DF

B3

39

DE

2F

DF

B3

BD

OB

0F40

D5

96

30

D6

2F

9B

OD

D9

OC

97

30

D7

2F

39

20

9C

OF50

20

AA

'20

C5

20

AB

20

D8

20

EO

CE

00

78

BD

07

A!

0F60

CE

00

6E

BD

07

Al

7C

00

IC

86

01

97

IE

BD

OE

15

0F70

BD

OF

79

86

OA

BD

C7

90

39

CE

00

98

BD

07

Al

BD

0F8O

07

93

81

59

26

03

BD

OF

C8

CE

02

DF

86

05

97

3C

0F9 0

DF

20

CE

00

93

BD

07

Al

DE

20

86

04

97

IA

A6

00

OFAO

27

25

BD

07

90

08

7A

00

IA

26

F3

BD

07

9E

A6

00

OFBO

BD

07

96

08

A6

00

BD

07

96

08

BD

07

9E

BD

07

9E

OFCO

7A

00

3C

26

D5

20

C5

39

CE

02

DF

7F

00

1 1

20

12

OFDO

C6

06

A6

00

Al

06

2D

06

26

1 2

08

5A

20

F4

08

5A

OFEO

26

FC

6D

06

26

EA

7D

00

1 1

26

DD

39

D7

IA

D7

1 1

OFFO

A6

00

E6

06

A7

06

E7

00

08

7A

00

IA

26

F2

20

E2

86

Notes on Memory to Memory Operation(Personal use notes by Carl Helmers)

As used in my homebrew 6800 system atB YTE, Jack Emmerichs' assembler is set formemory to memory operation without anysource input or object file output peripheraloperations at all. During the assembly pro-cess, the only normal 10 operation is outputof the listing to my Asciscope terminal at2400 bps. This form of operation is ex-tremely fust, and would be even faster if itwere not limited much of the time by thedata rate of the listing to the terminal. Thespeed is attained by use of large regions ofmemory instead of peripherals. At thiswriting, my 6S00 is equipped with a littlemore than 24 K bytes of working mainmemory which is allocated to the softwaredevelopment process in the first 2S K ofmemory address space as follows:

0000-OOFF Scratchpad direct address-ing region used by all pro-grams (like registers on abig machine).0100-OFFF 10 Device Address

Allocations.1000-IFFF Write protected program-mable memory for the In-teractive Manipulator Pro-gram (monitor, 10 rou-tines, text editor).2000-2FFF Assembler object file out-put built from 2000 up-ward, assembly time stackbuilt from 2FFF down-ward.3000-5FFF Source string text area pre-pared by IMP's editor.6000-60FJ Master initialization copyof directly addressedscratchpad memorycontents.60F2-6FFF Tiny Assembler 6S00 re-located by hand.In memory to memory operation, thepatches include programmed simulations ofthe nonexistent parts of 10, as well asa memory loader program which is patchedinto an appropriate part of the assembler toget data prior to conversion into externalform.

An Input Simulator

The normal CHRIN input routine of theM IK BUG monitor, or other similar systemssoftware, simply returns the next characterfrom the terminal device, which might be aTeletype, video terminal, etc. For memoryto memory operation this is accomplishedby use of a pointer variable and a routine

which fetches the next byte and incrementsthe pointer. If the pointer exceeds a maxi-mum value, the assembly is terminated withan error message, so my program assumesthat the end of the assembly will be sig-nalled by an END statement prior to run-ning out of data in the text string. End of line• to the assembler is indicated by the sameASCII carriage return (hexadecimal value D)which marks the end of line for the texteditor. The input simulator I use is illu-strated in listing 5; this routine also assumesthat initialization of the assembly sets thepointer named IPTR equal to the beginningaddress of the text buffer. It also is used toecho the original source listing of the as-sembly to the logical output devices. Thisalways includes the 2400 bps video ter-minal, but might also include my Teletypewhen I need a hard copy listing and set anappropriate monitor flag.

The Output Simulator

Output for the character images of theobject code of a line of assembled text arehandled exactly as in MIKBUG using rou-tines that accomplish the same purpose. Thedata goes to a terminal or Teletype hardcopy device in human readable form but isnot stored in machine readable form asassumed by jack. However, I wanted to beable to load the memory region from 2000to 2FFF with data generated by the as-sembler, rather than record the characterformat data on tape and later load it with aprogram such as that supplied by Jack inlisting 4.

Thus using the source listing of theassembler, I identified the location in theprogram (the beginning of WRITE) at whichall data for a given byte of memory is readyin binary form, then patched in the loader oflisting 6. This loader is patched into theassembler's WRITE routine, using codeshown by comments at the end of listing 6.This loader has been designed to calculate apointer into the output buffer area with thevalue 2000+X where X is the present outputprogram counter value minus the startingprogram counter value for the assembly.This technique works well provided that thestarting program counter can be properlyset. This is accomplished by setting thestarting program counter to an initial valueof FFFF during initialization, then making arequirement that the first statement of theassembly reference the starting address ofthe object code. This requirement is met bymaking the first statement of each assemblybe an ORG statement defining the startinglocation of the program being assembled.

87

Figure 1: Barcode representation of Tiny Assembler 6800. This figure, spread over several pages, contains the complete barcoderepresentation of Tiny Assembler 6800, version 3. The copy was sent to BYTE using Kansas City (BYTE) Standard tape format,and was processed by Walter Banks and his associates at the University of Waterloo to prepare the code in the form seen here.Table 2 was prepared from the same data using a different program for the Photon phototypesetter. The bar code text here usesvariable length records in the frame format described earlier in BYTE. This format is repeated here, along with the object codeformat, for reference by those individuals experimenting with bar code input techniques:

StandardFormat

Specific

DataFormat

Sync character, binary 10010110

Frame checksum (arithmetic sum of all bytes in frame ignoring carry)

Relative record identification, 8 bit ascending integer

Length of frame, "n "

Data of frame, total of "n " bytes, as follows:

• High order address for first byte of data

• Low order address for first byte of data

• "n-2" bytes of data loaded beginning at address of first byte of data

These records are absolute binary data, an image of the Tiny Assembler 6800 beginning at location 0000 and extending tolocation OFFF in memory address space. An extended segment of null (hexadecimal 00) data in the table area of the assembler isskipped, so not every byte in the assembler is found in this bar code representation (the same applies to table 2).

Listing 2: The main procedure loop of Tiny Assembler 6800. The assembly beginsby calling an optional subroutine, assumed to exist at the start of the symbol tableregion of memory, to perform user initialization. As assembled and presented in this article, thesubroutine is a dummy procedure represented by an RTS (hexadecimal 39) at location 02DE.The JSR STBL-I (hexadecimal BD 02 DE at location 7A4)-is the main entry point of theassembler. It can also be patched to a permanent initialization routine outside the assembler ifthe user's machine has more memory than the 4 K assumed by this program.

After user initialization, the symbol table is cleared. If the symbol table was present with atransient user initialization routine-starting at location 02DE, this routine is replaced by adummy return instruction for the second and subsequent invocations of the assemblerfollowing a load of the code.

Location ENTRY is the normal "continue assembly" entry point for the program. Ifassembling line by line, it is possible to invoke the assembler for one or more lines, issue anEND pseudooperation to terminate the assembly. Then it is possible to continue operation byreturning to ENTRY from your monitor (this listing assumes Motorola's MIKBUG). Note thatit is not safe to do such an END operation if there are any unresolved references, unless symboltable sorting is suppressed.

Overhead of interfacing Tiny Assembler to the Motorola MIKBUG monitor is part of theinitialization that precedes the call to CMD, the main assembly procedure. After an ENDpseudooperation, control returns from CMD, EOJ is called to perform housekeeping operations,and MIKBUG is reentered at $EOE3 (hexadecimal).

This listing and listing 7 were produced using the PL/I cross assembler version of TinyAssembler 6800.

Note: In order to interfacethis program to a nonMIK-BUG monitor, the details ofthe stack initialization at loca-tions 07C2 to 07C8 may needto be changed. In the earlierversion 2 of Tiny Assemblerused at BYTE, for example,the stack was initialized to fallat the end of the 4 K byteregion in which the assemblerwas located. In the newer ver-sion 3, adapted to use atBYTE, we initialize the stackpointer to the end of theoutput buffer area of memory.

407A4)

BD

02

DE 1

(0001)

07

A*

1

(07AM

CE

02

61 1

iU7AA)

6F

00

1

«07AC)

08

1

(CI7AD)

BC

07

BF 1

(07BOI

26

m

1

<07B2)

86

J9

I

4U7U'.)

H7

02

DE 11

(07B7I

CE

00

11

B8 1

(078A1

UF

2A

1

«07ac>

7F

00

1C 1

(07BFI

IF

00

31 1

407C2I

CE

07

B7 |

(07C5I

FF

A0

4B |

<U7C8>

BE

A0

7F |

«07CH>

CE

00

5<) 1

407CE)

BO

07

Al 1

(07011

HO

00

00 |

«0704)

BD

00

00 1

*07D7)

7E

to

E3 1

MAIN PHOCEDURE LOOPJSH STBL-1 EXECUTE OSFR ROUTINES

LDX *FTBL

CLH A

INX

CPX »STBL*l200

HNE CLH1

LOAA »*3<J

STAA STBL-1

clear the Symbol iable and ihe

FORWAHD JljMP TABLB

BLOCK FURTHER

EXECUTION OF UStR PROCS

THIS 15 THE CONTINUE ENTRY POINT

LDX

STX

#BUF1NXCHAP

CLH EOJFL

CLH P_POS

LDX WENTHY

STX SA04R

LOS *SA07F

LDX wriEADR

JSH STHOUT

JSP CMD

JSH EOJ

JMP SE0E3

INITIALIZE

INCOMING CHARACTER POINTERCLEAR FLAGq

LOAD SECONBAHY iNIHX POINT FOR MIKBUG MONITOR

LOAD STACK PUIMTbU FOR MIKBUG MONITOR*RITE OUTREADINGMAIN PROCEDURE LOOP - CALL PWOC-COMMAN05CALL END Of JOBJUMP TO MONITOR MAINLINE

000041MO008041*000004200•••000042100090422000004230000042«0

000042^0000042*00080*2100000428"00904290009043000000431000S043JU0090433"009043*000IO43|00090434"00004320009043*00090439000004490009044*0000044^0009044JO000044400090441(000904490

88

Figure I, part 1:

r

START HERE, SCAN DOWN PAGE FRAME IDENTIFICATIONS

0 1 2 3 1 5 6 7 8 9 10 tl 12 13 1.1 15 16 17 18 19 20 21 22 23 24 25 20 27 23 29 30 31 32 33 34 35 36 37 38 39 40

4t 42 43 44

^SSSSS3S|SSSSSSSSS3SSSS3SSS = = = = = = = = = = = = = =

89

Figure 1, purl 2:

^-SCAN DOWN PAGE FRAME IDEMTI FICATIONS

46 46 47 48 43 50 51 52 53 64 55 66 57 58 59 60 61 62 63 64 65 66 67 68 89 70 71 I? 13 /'I 75 76 77 78 79 80 31 32 33 84 85 80 B'l 88 89

90

Figure 1, part 3:

r

SCAN DOWN PAGE

FRAME IDENTIFICATIONS

90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 I 10 11 1 112 113 1 14 1 1 5 116 1 1 7 118 119 120 121 122 123 124 125 I2G 127 128 129 130 131132 133 134

91

Text continued from page 85

be similar from one microprocessor machinelanguage to another even though specificinstructions will differ. Like pseudocode,they can be combined into extremely com-plex procedures. One special structure is not

shown in table I: the code to handleexternal program linkages.

External linkage can be handled in twoways. One is to equate the name of anexternal symbol to an address and use itthroughout the program. This will generatethe absolute address of the external symbol

Table 3: Error messages from Tiny Assembler 6800. The format of labels, operation codes andoperands of Tiny Assembler 6S00 is a subset of the full Motorola Assembler specification.These error messages indicate conditions which Tiny Assembler could not handle; those con-ditions which are noted as "terminal" tend to propagate through the rest of the assemblygenerating additional errors. Error codes are single letters, listed here with some explanation.

ERROR A

Verb does not start with an alphabetic charac-ter. A verb is an operation code or pseudoopera-tion of the assembly language. This error can resultfrom a prior error, or from mistyping source data.

ERROR B

Verb not in table. This is the primary indicationof an invalid mnemonic operation code.

ERROR C

Verb does not allow immediate addressing. Anattempt was made to use immediate addressing(signified by a '#' character immediately precedingthe operand) with an operation that has noimmediate mode. For example.

ASR

=00 PS

would generate this message.

ERROR D

Invalid verb modifier.

ERROR E

Symbol table overflow. This is a terminal error,in the sense that code following a symbol tableoverflow can have spurious errors. To recover, theprogram being assembled should be partitioned sothat a smaller number of symbols is required inassembling each part. Note that the capacity ofTiny Assembler 6800 is 200 symbols in thisversion.

ERROR F

Label already in use. The following are severalsets of duplicate labels (as interpreted by TinyAssembler 6800):

In Label Field

THINKS

THIS

THIMBLES

AOUT1XAOUT2XAOUT3X

In Symbol Table

THIS

AOUX

three characters and last character must be unique.ERROR G

Relative branch greater than 128 locationsaway. This error occurs if the target of a branchinstruction is too far away for a signed 8 bitdisplacement from the present location countervalue. This can usually be fixed by using a jumpinstruction. For example, if

BMI

TARG

While symbols can be arbitrarily long, the first

gives error G, then it might replaced by thecomplementary condition and a jump as follows

BPL DUM1

JMP TARG

DUM1 *•• continue code ***

ERROR H

Forward reference table full. This is a warningmessage that indicates imminent collapse of anassembly if another reference to an undefinedsymbol is found prior to the resolution of anypreviously unresolved reference. Tiny Assembler6800 has a table of 25 unresolved forwardreferences maximum.

ERROR I

Forward reference table overflow. This is theterminal message that indicates an attempt toexceed 25 unresolved forward references. Afterthis error is noted, there will typically be numerousspurious error messages. Eliminate forward refer-ences to undefined labels to cure this problem. Oneway to eliminate an unresolved forward referenceis to define the data or code involved prior to itsfirst reference.

ERROR J

Invalid character in hexadecimal or decimalnumber. Only two types of numeric constant areallowed by Tiny Assembler 6800: up to fourdecimal digits, or a dollar sign ($) characterfollowed by up to four hexadecimal digits.

ERROR K

Invalid symbol. A symbol in the label field ofan operation begins with a number, or an invalidcharacter is detected in a symbol.

92

for each instruction which references it. Abetter way is to create a table of linkages toexternal symbols and have all references gothrough the table. In this way, only onestatement must be changed if the location ofan external symbol should change. If allreferences are in the form of subroutinecalls, a simple jump statement can be used totransfer control from the table to the ex-ternal location. In this assembler, all calls tothe monitor's 10 routines go through thetable shown in listing I.

The CASE statement is somewhat morecomplex. The pseudocode for CASE isshown in table 1 in two forms. The pseudo-code can be broken clown into two func-tions: calculate the CASE conditions, and

Listing 3: Symbol table allocations. The $01 code at 02DE is a NOPinstruction which gets replaced by a $39 to block further attempts atinitialization after the assembler has cleared the symbol table. A dummytransient initialization routine of three NOPs and an R.TS illustrates how suchcode would be entered into the assembler's source; in a real situation, onewould assemble the initialization routine separately and then move the codein on top of the existing assembly code of this dummy.

<0<?0t)♦02UF)

(02UF)

01

<02E0)

01

402E1)

01

(OdE^l

39

4078FI

<07«F)

00

SYMBUL TABLF

FCb 101

RMB 0

LABEL NAME

CHAR 14)

LABEL ADUR

CHAR <<i)

NOP

SPACE FUR

NOP

USER DEFINED

NOP

ROUTINES

HTb

OPta bTBL»120C

SET FOR dOt!

FCB 100

TABLE STOP B

Listing 4: An example of a ioader program. This loader is based on the functional structure shown in the first part of this article,and is one of several listings accompanying this article which show how Tiny Assembler 6800 works.

LOCN Bl B2 B3

0000

0000

0000

0000

0000

0000

0000

0000

0000 7E

0F79

0F79

0F79 7E

0F7C 7E

0F7F 7E

QF82 7E

0F85 7E

0F88

***************************f ASSEMBLER DIHECTEI LOADER

***************************EXTERNAL REFERENCES

EO E3E0 47EO 5 5El ACEO 7E

0F880F88

000 D000A00040F88 OD0F8B 000F8C 200F8F 4 70F92 04OF93 OD0F96 000F97 200F9A 4E0F9C 040F9D ODOFAO 000FA1 ao0FA4 44OFA7 48OFAA 20OFAD 52OFSO 040FB1OFB10FB10FB10FB1

0FB1 CE 00

0001 OF Bl0FB4 6F 000FB6 8C OF0FB9 27 00OF LB 08OFBC 20 f6OF BE CEOFBA 030FC1 BD

>BEGIN

>BUG

>INADDK

> INHEX

> INCHAR

> PUT SIP.

>CR>LF»EOT> PROMPT

42 4549 4E

OA 00

42 4120 4341 524 5 524F 52

ORGJMPORG

EQUJMPJMPJMPJMPJMP

EQUEQUEQUFCB

FCC

0

CLE AhSOF79

* LABEL BEGINING

£E0E3 MONITOR MAINLIN

$E047 ADDRESS IN

SE055 HEX BYTE IN

SE1AC CHARACTER IN

SE07E PUT STRING OUT

****************** .* + * + *** +

GENERAL DECLARES

****************** ********

SD DEFINE CONTROL

SA CHARACTERS

CR'LFj

DEFINE. OUTPUT STRINGS

- FCB EOT

•DONE FCB CHiLF*

> FCB EOT

>EBHMS<3 FCB CR'LFi

FCC 15, RAD CHAR ERROR

FCB EOT

OF 8 8OF 85

*

START

LOADER

**** *

******

********

******************

CLEAR

LDX

#0

BLANK OUT FIRST

LOOP

CLR

X

OF MEMORY

CPX

#BEG IN

EXCEPT LOADER

HEQ

GO

1NX

BRA

LOOP

GO

LDX

•PROMPT WRITE OUT

JSR

PUTSTR

PROMPT STRING

0FC4

BD

OF

82

>FNDADR

JSR

INCHAR

READ NEXT CHARACTER

0FC7

81

00

>

CMPA

#0

IF END Oh TAPE THEN

0FC9

27

00

>

BEQ

EOJ

GO TO END PROC

OFCB

81

2H

>

CMPA

* ' (

IP NOT '< ' THEN

OFCD

26

F5

>

BNE

FN DA PR

TRY NEXT CHAR

OFCF

BD

OF

70

>

JSR

IiNADDR

ELSE READ START ADDR IN

0FD2

BD

OF

82

>NXTBYT

JSR

INCHAR

REAP NEXT CHAR

0FD5

81

29

>

CMPA

* ' )

IF END, OF BLOCK THEN

OFD7

27

KB

>

BEU

FNDADH

GO FIND NEXT BLOCK

0FD9

81

20

>

CMPA

* SgQ

IF NOT A BLANK THFTN

OFDB

26

00

>

PNF

ERROR

DO TO ERROR PROC

OF DP

BD

OF

7F

>

JSR

INHEX

REAP NEXT CHAR INTO 'A'

OFEO

E6

00

>

L DA B

X

LOAD CURRENT VALUE INTO

0FE2

IB

>

ABA

ADD 'A' AND 'R'

OFE3

A7

00

>

5TAA

X

STORE ANSWER IN MEMORY

OFE5

24

00

>

BCC

COUNT

If- CARRY THEN

0FE7

09

>

LEX

INCREMENT HIGH OR] ER

0FE8

6C

00

>

INC

X

OFEA

08

>

I NX

OFEB

08

>COUNT

I NX

SET IX FOR NEXT PYTF

0FE6

04

OFEC

20

E4

>

BRA

NXTHYT

LOOK FOR NEXT CHAR IN B

OFEE

>

OFEE

>

OFEE

> * * * * * *

* * * *

*******

***********************

Or HE

> *

ERROR

ROUTINE *

OF EE

>,*****

************

*»,*********.**********

QFEK

CE

OP

<JD

>ERROR

LDX

#ERHMSG

PUT OUT ERROR M5G

OP DC

1 1

OF F 1

Bb

Or

H-j

>

JSR

PUTSTR.

Orf-4

VE

OF

79

>

JMP

PUG

RETURN TO MONITOR

OFF/

> * * * * ¥ f

*** *

* ******* * ** ***************** * *

Of F 7

>*

END OF

JOB R.OUTINE *

0FF7

>***********

*******

t**********************

OF F 7

CE

Of-

93

> El) .J

L DX

BDONE

PUT OUT FINISH MSG

OFCA

2C

DM* A

BD

OF

85

>

JSR

PUTSTH

OFFD

7E

OF

7 9

>

JMP

HUG

RETURN TO MONITOR

1000

>*

1000

> *

1000

■■>

END

*** UNRESOLVED ITEMS

HEGN

0 F 7 9

BUG

0 F 7 9

CLER

0FR1

GOUT

OFEB

CR 0 00

DONE

0 F 9 3

EOJ

0 F F 7

EOT

0004

ERRG

OF >]

errr of;:

KNDR

OF C4

GO

OFRE

INAR

0 F 7 I;

INCH

0 F 8 a

IN-IX OF 7

LF

OOOA

LOO?

0 FP 4

N < T T

OF pa

PHOT

0P«8

PUTT OF*

93

Listing 5: The input simulator routine. This routine, coiled exactly like theequivalent routine of MIKBUG, simulates an input operation by fetching thenext byte of text from the text area. This byte is written to the terminaldevice to echo the progress of the assembly. The character string outputsequence referenced on input overrun error is designed to use a string whichterminates with hexadecimal FF. For users of the equivalent STROUTroutine of MIKBUG, replace the last character of the message string withhexadecimal 04.

LOCN20002000

aooo

200020002000200020002000

aooo

200020002000200000F400F2200020002000FFFF200020002000200010410020OOFCOOFF0007OOOD200020002000

aoooaooa2004aoo6aoo7

200A200C

aooE

200F

aoioaoi3

2011201520162016201620082019

aoiBaoiE

CE> ORG 12000

>* ORIGIN CHOSEN TO EASE RELOCATION BY USERS OK LISTING>*

>« MEMORY TO MEMORY ASSEMBLY INPUT ROUTINE>» FOR USE WITH JACK EMMERICHS'>« "TINY ASSEMBLER 6800" PROGRAM

>» WRITTEN BY CARL HELMEHS CIRCA NOVEMBER 15 1976

>* ORIGINAL VERSION HAND ASSEMBLED

>» THIS VERSION EDITED AND ASSEMBLED FEBRUARY 11 1977

>» AS ILLUSTRATION FOR JACK EMMERICHS' ARTICLE

>* IN MAY 1977 BYTE- ••

>*

>* EQUATES OF VARIABLES

>TEMX EQU 1F4 TEMPORARY INDEX SAVE AREA

>IPTR EQU 1F2 POINTER TO INPUT TEXT AREA

>» ASSEMBLER PATCH FOR OUTPUT TO TERMINAL>OUTC EQU SFFFF [REPLACE WITH ACTUAL VALUED

IMP6800 MONITOR EQUATES

FUR STRING OUTPUT PACKAGE DATA

>PSTR EQU>TXTX EQU>CLEA EQU>STOP EQU>BELL EQU>CR EQU

11011ISOSFCSFF

17ID

PUT STRING ROUTINE

PUT STRING POINTER INPUT ARGUMENT

PSTR CLEAR SCREEN COMMAND

PSTR END UF STRING COMMAND

ASCII BELL

ASCII CARRIAGE RETURN

EXECUTABLE CODE OF NXCH "NEXT CHARACTER" ROUTINE

DF F4DE Fa

A6 00

08

SC 5F FF

a 7 00

DF F2

36

37

BD FF FF

33

3a

39

>NXCH STX TEMX

> LDX IPTR

> LDAA O.X

> INX

> CPX

> BEQ

> STX

> PSHA

> PSHB

> J5R

> PULB

> PULA

> RTS

#15FFF

OOPS

IPTR

A l« tIPTH [GET NEXT INPUT CHARACTER]

IPTR I" IPTR ♦ 1)

IF IPTR ■ 15FFF THEN

COOPS WE HAVE AN ERROR]

PRINT THE CHARACTER

>* ERROR DISASTERCE 00 00 >OOPS LDX #UOPM

NORMAL RETURN

X I- [ADDRESS OF MESSAGE]

DF ao

BD 10 1120 FE

2080 FC

2023 07

2017 20

2025 49

2028 55

202B 42

302E 46

ao3i ao

2034 452037 55a03A OD203B 07203E OD204!

07 ODOD20

4E 50

54 20

55 4645 534F 56

sa sa

4E 20

OD 07

0 7 FF

STX TXTX TXTX I- ADDRESS OF MESSAGE

JSR PSTR PRINT MESSAGE [IMP MONITOR HUUTINE)

■GAGA BRA GAGA RUN AMUCK IN CONTROLLED LOOP TILL RESET

•OOPM FCB CLEA»BELL#CR-BELL#CR

FCC aa.INPUT BUFFER UVERRUN I

FCB BELL,CR,BELL.CR.BELL,STOPEND

UNRESOLVED ITEMSl

*** SYMBOLSl

BELL 0007 CLEA OOFC CR OOOD GAGA ao1E IPTR 00K2

NXCH 2000 UOPM 2020 OOPS 2016 OUTC FFFF PSTR 1041

STOP OOFF TEMX 00F4 TXTX 0020

then execute the proper case procedure. Intable I, the second form of the CASEconstruct and the detailed code shows thisrestructuring. The implementation of thisstructure resembles a computed GO TO, andis shown in detail in table 1. Unlike acomputed GO TO, however, there is onlyone logical exit from the routine. This is a

return from subroutine (RTS) instructionalthe end of the select procedure. In theassembler, the CASE structure is used toselect which procedure is to be executed forassembler directives. In our model CASE oftable 1, a branch around the structure isshown for completeness; this is not neces-sarily required in all cases.

During the process of translating eachfunction into assembler code, it was notdifficult to follow the coding techniquesdeveloped above. Control logic is not com-plex because control instructions generallyfall into two simple categories. First, withina given function there are almost alwaysbranch instructions which arc limited inrange from —128 to +127 bytes relative tothe location of the next instruction. Eachfunction is usually compact enough to fitwithin this range. Second, between functionscontrol instructions are always subroutinecalls. The only way for one function toaffect another is through a jump to sub-routine, or by changing values in programvariables or machine registers. This makesthe program very easy to understand andmodify. /Proven in practice here at BYTEwhere Jack's assembler has been undergoinga bit of customization. /

Trying It On a Real Machine

The problem of machine access was fi-nally solved by my friendly local MilwaukeeComputer Store which donated the use of ademonstrator Southwest Technical ProductsM6800 for debugging the final version of theassembler. The final phase of the projectcould now begin.

The main line and 10 modules were de-bugged first so that the program couldcommunicate with the user. Functions weretested in the same top down order used indesign. Once a function worked properly itwas almost never necessary to make furthercorrections based on the testing of lowerlevel modules. Listing 2 shows the main lineprocedure of the assembler, with some com-ments on its operation. Listing 3 shows thesymbol table allocations with comments ontransient user initialization performed bycode in the symbol table area.

Examples of how the assembler works areshown in listings 4, 5 and 6. Listing 4 is aloader program based in part on the func-tional description in pseudocode developedearlier and shown in listing 5 of part 1 ofthis article. The style of this loader reflectsits use as an example of assembler sourcecode more than its possible use as anefficient, compact loader. Listings 5 and 6supplied by Carl Helmets are examples ofwhat can be done to adapt the assemblyprogram.

94

Listing 6: An object file output simulator. This routine, which is patched into the assembler's WRITE routine of hexadecimallocation 8B2 (68B2 in BYTE's relocated version), is used to directly load the output of the assembler into the output bufferstarting at location 2000. A starting address pointer is initialized in BASE by the first address generated in the assembly, and allother addresses are calculated by subtracting the starting address pointer from the current address then adding the origin of theoutput buffer. The load routine results in a memory image of the final program out of the assembler, complete with all patchesand fixups required by the one pass nature of the assembler. After an assembly, the MOVE routines of the monitor used atBYTE relocate the program at its intended position in memory. No loader or linkage editor is used in this system, and absolutetext is all it produces; relocation of programs is done by reassembly with a different ORG value at the start of the text.[Note . . .This memory loader routine assumes that the output area of the assembly is cleared by initialization prior to entryinto the assembler. If this is not done, change locations 203A and 203B to NOP instructions (hexadecimal 01). In either form,this routine will not calculate undefined forward reference expressions properly. For an example of the correct code for theundefined forward reference expression special case, see locations FEO to FEB of Jack's loader program in listing 4. . . . CH]

Summary and Reflection

What has been presented here as achronological listing of project activities wasin fact accomplished with a fair amount ofoverlap. For example, a complete descrip-tion of the Motorola M6800 language wasnot available to me until after the crossassembler was partially completed. Finaltable optimization was not achieved untilafter a version of the program was opera-tional on the M6800 machine. Ideas came uplate in development which could increasecapacity or decrease overhead. In all suchcases, the structured format of the programallowed modifications to be easily incor-porated into existing code.

There are several possible modificationsthat arc loo major to be incorporated intothe initial version of this assembler andwhich fall outside of the original specifica-tions. These can be considered for futureprojects or may suggest still other modifica-tions to some readers.

For example, the biggest constraint uponthe use of a small assembler is the small sizeof the symbol table. One way to overcomethis problem is to be able to delete a symbolwhen it is no longer needed and reuse thetable space. A good way to do this is toimplement a BEGIN statement. This wouldpush the location of the most recent symboladded to the table onto a table stack. Allsymbols defined below this point wouldbelong to this BEGIN block. An ENDstatement would pull the top location offthe table stack and delete all symbols belowbut not including this location. If there wereno items in the table stack, end of programwould be signaled. The nesting level ofBEGIN blocks is only limited by the tablestack size. This is similar to the way BEGINand PROCEDURE structures work in PL/Iand should be quite easy to implement in asequentially searched symbol table.

If more memory were available, thisassembler could be combined with an editor

LOCN20002000200020002000200020002000200020002000200020002000200020002000200020002000200020000031OOFC200000F600B500B300F4OOFE2000200020002002200420072009200B200D200F20 1 120 132015200820172019201B201D201F202120232025202720292028202E20302032203420362038203A203C203E203F2041204320332044204520472049202A204C204F204F204F204F204F204F204F

• ORG 12000

>* MEMORY TO MEMORY ASSEMBLY LOADER

>» MODIFICATION FOR JACK EMMERICHS' "TINY ASSEMBLER"

>* PATCHED INTO WRITE ROUTINE DUMP DATA TO

>* LOCATION 2000-2FFF FOR LATER MOVEMENT TO FINAL LOC

>* BASE MUST BE INITIALIZED TO "FFFF" PRIOR TO ENTRY

>* WRITTEN BY CARL HELMERS. DECEMBER 9 1976 AS UPDATE

>* TO ORIGINAL MUD CIRCA NOVEMBER 15 1976

>*

>» VERSION OF FEBRUARY 14 1977 ASSEMBLED FOR JACK EMMERICHS

>* MAY 1977 BYTE ARTICLE TO ILLUSTRATE ADAPTATION.

»« EQUATES TO ASSEMBLER VARIABLES ADJUSTED FOR VERSION

>* 3 ASSEMBLY OF "TINY ASSEMBLER 6800"

>* ORG TO LOCATION S2000 TO EASE RELOCATION ...>* ACTUAL LOCATION IS INSIDE IMP6800 MONITOR BUT>• IT'S EASIER TO HAND RELOCATE IF LOW ORDER ZEKOS>* ARE FORCED INTO ADDRESSES

>* TAPE #200A LOC 188 FILE-LOADER

>PP0S EQU S31 ASSEMBLER PRINT POSITION

>BASE EQU SFC CURRENT BASE ADDRESS/ FFFF INITIALLY

=■» NOTE! ASSEMBLIES MUST START WITH "ORG" TO SET BASE

>PTR EQU SF6 OUTPUT POINTER. 2000-2FFF RANGE

>BYT1 EQU 1B5 ASSEMBLER'S OUTPUT STRING ADDRESS

>OUTA EQU SB3 ASSEMBLER'S CURRENT OUTPUT ADDRESS

>TEMX EQU JF4 TEMPORARY SAVE AREA

>ISX3 EQU SFE REALLOCATION OF ASSEMBLER VARIABLE TO AVOID

>* MONITOR CONFLICT

DF FE

DE FC

8C FF FF

26 00

96 84

80 00

9 7 FD

96 B382 209 7 FC9 6 B4OC

90 FD

97 F796 B392 FC9 7 F69 6 F780 FF96 F682 2F24 00

CE 00 B5

C6 01

Dl 31

2C 00

A6 00

DF F4

DE F6

AB 00

A7 00

08

DF F6

DE F4

08

OF

5C

CI 04

26 E7

CE 00 73

IE

7E 68 B7

>LDER STX ISX3

> LDX BASECPX #SFfFF

» BNE NORL

> LDAA OUTA+1

> SUBA *0

> STAA BASE+1

> LDAA OUTA

> SBCA #S20

> STAA BASE>N0RL LDAA OUTA+1

SUBA

> STAA

> LDAA5BCASTAA

> LDAA

> SUBA

> LDAA

> SBCA- 8CC

> LDX

> LDAB>LDR1 CMPB

> BGE

> LDAA

> STX

> LDX

> ADDA

> STAA

> I NX

> STX

> LDX1NX

BASE+1

PTR+1

OUTA

BASE

PTR

PTR+1

*SFF

PTR

#$2F

NOLO

#BYT1

»1

PPOS

LDR2

O.X

TEMX

PTR

O.X

O.X

PTRTEMX

SAVE INDEX AS IN ORIGINAL CODE

IS BASE EQUAL TO NULL INITlALIZATIUN?IF NOT THEN GO TO NORMAL EXECUTIONELSE COMPUTE A BASE ADDRESS

BASE » OUTA - 12000

CALCULATE OUTPUT BUFFER ADDRESS

PTR ■ OUTA - BASE

- OUTA(N) - 0UTA<0)

>LDR2

INCB

CMPB #4

BNE LDR1

■NOLO LDX #S73

IS PTR LESS THAN S2FFF?

IF NOT THEN DO NUT WRITE DATA AT ALLPOINT TO ASSEMBLER OUTPUT STRINGSIMULATION OF ORIGINAL OUTPUT

COMBINE NEW DATA WITH OLDPOINT TO NEXT OUTPUT BYTEPREPARE FOR ITERATIUN

SET INDEX AS IN ORIGINAL CODE

JMP S68B7 JUMP BACK Tu ASSEMBLER AFTER PATCHTHE FOLLOWING ABSOLUTE CODE IS PATCHED INTO THEASSEMBLER AT ITS LOCATION STARTING AT ADDHESS 6000..6882 7E XX XX WRITE JMP LDEH

CNOTE XX XX IS ACTUAL ADDHESS 01- LDEH.

NOT DUMMY 2000 OSED FUR THIS ASSEMBLY ONLY I

END

UNRESOLVED ITEMSl

BASE OOFC BYT1 00B5 ISX3 OOFE LDEH 2000 LDH1 2030LDR2 2043 NOLO 2049 NORL 2015 OUTA 00B3 PPOS 0031PTR 00F6 TEMX 00F4

95

Listing 7: A muitifaceted sample of various features with comments. Thecomments in this assembly refer to features of the assembler; the actual codeis arbitrary and is not intended as a coherent program. Errors iisled in table 3are illustrated at the end of the assembly.

LOCN Bl BS B2

0000

0000

0000

0 100

0003

0100 8E 00 00

0103 FE 00 00

0106 C6 030108 96 OA010A Al 02010C 27 000tOE 090 1 OF 5 A0 110 2 6 K60112 Al 000 1 14 3E

0115 BD 00 00

0 10D 07

01 IB0118

011R B6 01 0001 IB 7F. 01 15DUE 16

0116 01 IE

011F BA 00 00

0 122 39

0 123

0 1 2D

0 10 1 0 1 2D

0 12E 80

0 120 0 1 2E

0 12F

0 12F

012F in 00 04

0 132 20 32

0 134

0 134

0 1 34

0 134

0 134 49 54 4b

0 13 7 4IJ 5 3

0 139 0 1 34

0 104 0 1 39

0 1 3B

0 1 3B

0 13B 8 6 20

*** ERROR - A

013D

*** ERRUR - B

0 13 Li

*** ERROR - C

0 1 3 0

*** ERROR - I)

013D

*** EHROR - K

013D

»** EKHUR - G

0 1 3D 20

*** ERRUH - J

013D

**+ ERROR - U

OHO J

00 FF

0 13D 96 00

0 13F

+** ERRUR - K

013F

*** ERROR - K

0 13F

0 13F B6 yf Fl

0142 B6 00 00

0 145

0145

0 145

0 145

0145 7E 00 00

014H

>* SAMP

ORG 256

■CUNT EQU 43

■STRT LDS #STAK

LUX ADDR

LDAB ICUNT

•BACK LDAA 10

CMPA 2*X

BEQ FUND

DEX

DECB

BNE BACK

CMPA X

UAI

-FUND JSR SRTN

L E ILLUSTRATES WITH COMMENTS

DEFAULT IS A DECIMAL NUMBER"&" INDICATES DECIMAL/ TOOA FORWARD REFERENCEANOTHER FORWARD REFERENCEIMMEDIATE ADDRESSIN IF "#"DIRECT ADDRESSING IF <= 2S5 ($INDEXED ADDRESSINGRELATIVE C BRANCH) ADDRESS!NUIMPLIED ADDRESSINGACCUMULATUR ADDRESSING

DEFAULT U OFFSET INDEXED ADDR-

WAII FUR INTERRUPT

JUMP TO SUBRUUTINE CCALL)

CNOTE hUHWAHU REFERENCE IS RESULTED HERE ANDPATCHED INTO EARLIER BRANCH-]

LDAA STRT

UMP hUND-SRTN TAB

ORAA BYTERTS

RMB 10

•STAK RMB 1

•BYTE FCB 180

EXTENDED ADDRESSING

JUMP UNCONDITIONAL

THESE ARE COMMENTS --

rURWAHD KEF* EXTENDED ADDK-

RESEHVE 10 BYTES MEMuRYSTAK NUW RESOLVED

J-URM CONSTANT BYTE>"S" FuR

•DATA•ADDR

CNOTE RESOLUTION OF EXTENDED ADDRESS*AND BACKWARD PATCH-.. JSl0w4.-32.S32 FORM SEVERAL CONSTANT BYTES.

WITH NULL INDICATED BY ".."; NOTE USE Ut- "4" FUH HEXADECIMAL* AND UNLY ONE SPACE Al START U> LINE . FIRSTCHARACTER IS "*" >Uri COMMENT* " " FOR UNLABELLED LINEAND ALPHANUMERIC i- UR SYMBOL DEFINITION.1-CC 5..ITEMS fURM 5 CHARACTER STRING

FDB DATA

•* NUW SUME ERRURS

LDAA #10!I$20•LDAA 5

LDA AjS

STAA *DATA

STAA 5.W

•DATA FCB 10

BRA SFFKF

LDAA lfiFF

•I TErt EQU SOOKX

J-UKM 2 BYTE ADDRESS

UjE Uf "lM AS DELETE CHAK*

LEADING BLANK MISSING

"A" SEPARATE FROM "LDA"IMMEDIATE ADDRESS IMPOSSIBLE"tf" SHOULD Bt "X"DUPLICATE LABEL (SYMBULJBRANCH UUT Uh RANGE.INVALID DECIMAL CONSTANTINVALID HEXADECIMAL CONSTANJCURRECTIUN TU ERRUH

EQU SFHLDAANULL OPERAND FIELD ABUVE EQUATED TU £EKu

LDAA % 10 10 MUTURULA'S BINARY NUT SUPPORTED

LDAA H3

MUTURULA'S OCTAL NUl SUPPORTED

LDAA STHT+2-DATA+S23 VALID EXPRES^IUN

LDAA STRT/2-DATA*S23 INVALID EXPRESSIONCNUTE: INVALID EXPRESSlUN RESULTS IN BAD DATA. NUMESSAGE AND SEVERAL SPURIOUS ENTRIES IN SYMBOLTABLE J

JMP UNDEFINED 1-URWARD REFERENCE LEFT UNRESOLVED AT

END

UNRESOLVED ITEMS!

STR2DAT3UNDD

ADDR 0139 BACK 0108 BYTE 0I2E CUNT 0003 DAT3 0000DATA 0134 FUND 0115 ITEM OOFF LDAA 01 3D SRTN 01 IESTAK 012D STR2 0000 STRT 0100 UNDD 0000

lo produce an assembling editor. Theeditor's insert, find, delete and modify func-tions in addition to an assembling functionand a reasonably sized source file bufferwould provide quite a nice program develop-ment package using about the same amountof memory required by most otherassemblers.

In a large system, the assembler could bereassembled for a higher memory locationand then used to load the developed objectcode directly into available lower memorylocations. This would eliminate many of the10 timing considerations mentioned lastmonth and the need for a loader program.

While the current package can handlelarge and complex programs (such as itself)and could be developed into even greaterthings, it is initially intended to meet moremodest requirements. As a Tiny Assembler itis well suited for small programs that can beentered by hand or from fairly short inputtapes on a Teletype. It is an excellent toolfor the interactive development of func-tional blocks for a large structured program.Different methods of coding a given processcan be tried to allow the user Lo examine thegenerated code. Changes can be made aserrors are flagged or new ideas come up bysimply backing up the program counter andrecoding. (Here the loader must replace whatis in memory rather than add to it, orchanges will be added to errors.) Finally, ifyour 6800 based machine only has 4 K ofmemory, this is probably the only assemblerthat you can use at all."

Adapting Tiny Assembler 6800

The size of the source listing (over 40pages) for Tiny Assembler 6800 prevents usfrom presenting the listing in the pages ofBYTE. Since a source listing and moredetailed user notes arc items which shouldbe available to anyone seriously interested inmodifying or extending this software, we aremaking available a PAPERBYTES book byJack Emmerichs, entitled Tiny Assembler6800. This book contains a reprint of thetwo articles by Jack which have appeared inBYTE, plus additional user manual materialsand the complete source listing of TinyAssembler 6800 (along with object code incross assembly format).

This assembler is a valuable programmingaid for systems with limited memorycapacity which can free you from thedrudgery of machine language. The bookwill be available soon. For ordering informa-tion and price, watch for ads in upcomingissues of BYTE.

96

\6

top vcilueAprofes/ionali/m

Computer Shack stores areexciting, enjoyable placesto visit. From the strikinginterior decor to the fun andchallenge of the GAMEROOM, you'll find ComputerShack stores a completelynew computer shoppingexperience.

You can count on ComputerShack stores for total profes-sional support whether yourneeds are those of a com-puter hobbyist, education,science or business user. Theskilled, management-trainedstaff offers knowledgeableservice, expert maintenance,and software guidance.

quality product/

At Computer Shack storesthe emphasis is on qualityproducts. Featured are thefinest in microcomputers,interfaces and peripherals,including the full IMSAI line.Every store is completelystocked with tools, booksand a complete line ofaccessories.

NOW OPEN

2 DeHart St., Morristown, NJ 07960

(201) 539-407722680 Foothill Blvd., Hayward, CA 94542

(415] 538-80806840 la Cienega Blvd.,

Inglewood, CA 90302 (213) 776-8080

COMING SOONMISSION VIEGO, CATUSTIN, CASAN DIEGO, CA

beginner/welcomed

Do you want to get startedwith microcomputers? Areyou seeking expert guidanceon computers, peripherals,software? The place to visitis your nearest ComputerShack.

Watch your local newspaperfor Computer Shack open-ings. Each store features amonthly Sales Special.

1922 Republic AvenueSan Leandro, CA. 94577(415)895-9363Franchise OpportunitiesAvailable

Last month author Mike McNatt described a number of Baudot typeteleprinters that are available on the surplus market today. Let's assume thatyou have since rushed out in the intervening period and acquired your ownBaudot teleprinter. To use it with your system, some method must be devisedto enable communication between the processor and the serial Baudot device,Mike's topic in this second part of a 3 part series.

A Guide

Michael S McNatt4658 E 57 StTulsa OK 74135

To use a Baudot page printer or keyboardwith your computer system, some methodmust be devised to enable communicationsbetween the processor and the serial Baudotdevice. Traditionally, these interfacemethods have been classified as either soft-ware or hardware. Both methods seem tohave supporters who are radically convincedthat the method they've chosen is the best.Strictly speaking, none of the Baudot ma-chine interface methods can be called purelysoftware or purely hardware; they all liesomewhere in between. However, the hard-ware code converter obviously requires theleast amount of new software generation.

Hardware Interfaces, Code Converters

The chief advantage of these converters isthat they allow the use of Baudot machineswith computer software which is written toinput and output exclusively in ASCII code.This is a major factor when you considerthat much of the microcomputer softwareavailable is written with ASCII IO. Figure 1illustrates the use of these converters, whichconsist of circuitry to (a) convert the parallelASCII code from the processor data bus intoserial Baudot code for use with page printersor paper tape perforators or (b) convert theserial Baudot output from a keyboard ortape reader into parallel ASCII code forpresentation to the processor data bus.

When using hardware conversion fromASCII to Baudot, a handshaking arrange-ment is used whereby the Baudot machinetells the processor when it is ready to accepta character. Parallel ASCII data generated bythe program's output routine is then strobedinto the converter via a load pulse from theprocessor.

The converter's ready line changes logiclevels, indicating that it is in a busy slate.During this state, the processor stands bywhile the converter

1. generates a figures or letters shiftcharacter if required,

2. converts the shift character into serialpulses which are sent to the Baudotmachine,

3. converts the parallel ASCII characterjust loaded into an equivalent parallelBaudot character via a programmableread only memory lookup table, and

4. converts this new Baudot characterinto serial pulses which are sent to theBaudot machine.

The converter's ready line then changesback to its original state, indicating that it isready to accept another character.

A variation of this approach which maynot require busy and ready handshaking isto use a long, serial shift register buffer. Thiswould in effect compensate for speed dif-

98

MICROPROCESSOR10 PORTS 8 BITPARALLEL ASCII

ASCIIKEYBOARD

VIDEOTERMINAL

SERIAL BAUDOT TOPARALLEL ASCII

PARALLEL ASCIITO SERIAL BAUDOT

^

/-'

, r

,

. i

i

CODE CONVERTORS

''

BAUDOTKEYBOARD

BAUDOT

PAGE PRINTER

PAPER TAPEREADER

PAPER TAPEPUNCH

I i

HIGH VOLTAGELOOP SUPPLY

Figure 1: The block dia-gram describing the use ofhardware code convertersinterfaced with amicroprocessor.

to Baudot Machines:

Part 2, Interfacing Techniques

ferences in an ASCII 110 bps serial outputand the slower 45 to 75 bps rates of theBaudot machines. Since most interface mes-sages are less than one line of 88 charactersin length, one line of shift register bufferingmay suffice; see reference 22, volume 2, #1,January 1976, page 9.

When using hardware conversion fromBaudot to ASCII, serial pulses from theBaudot machine are loaded into a shiftregister and presented as five parallel linesrepresenting one character to another readonly memory lookup table. Circuitry in theconverter keeps track of whether the char-acter has been preceded by a letters orfigures code, and presents this informationto the read only memory as a sixth inputline. When the parallel ASCII output fromthis memory is ready, the converter gen-erates a data ready pulse, during which theprocessor loads in the ASCII character. Thisconversion operates in a manner similar tothat of a standard ASCII keyboard whichgenerates a strobe or ready pulse after eachkeystroke, indicating that the character maybe loaded into the processor.

Circuits for accomplishing these conver-sions have been published, (references 11,

11a, 15, 16, and 21) and are available asprinted circuit board assemblies from severalof the companies listed in a separate boxlabelled "Sources of Baudot Hardware." Ref-erences 9 and 10 present parallel to parallelcode conversion circuits which require anadditional UART or similar circuitry toobtain serial data for, or from, the Baudotmachine.

Software Interfaces

In the purists' software approach, oneroutine is used to construct the serial Baudotcode for output, and another routine is usedto decipher the incoming Baudot code forinput to the operating program. Routinesused to accomplish these functions are some-times referred to as timed software, since thebit timing of each character, 60 wpm, 100wpm, etc, is derived from software timingloops. For example, to derive the precise22.0 ms pulse periods required for 60 wordsper minute operation, a set of instructionswhich requires 12.7 ms to execute would berepeated 1,732 times for each bit of serialdata.

The hardware requirement is held to anabsolute minimum in both the input and

99

output interfaces. The processor serial out-put interface can be a simple two transistorcircuit, optoisolator or relay which opensand closes the teleprinter's current loop.

Several comments observed in the RTTYJournal (September 1973, page 13, for exam-ple) indicate that a Motorola MOC 1000optical coupler has been used successfully up

GLOSSARY OF TELETYPE TERMS

AFSK: Audio Frequency Shift Keying; see Fre-quency Shift Keyer.

ASR: Automatic Send and Receive. Refers to ateleprinter system which includes a page printer, akeyboard, a paper tape punch and a paper tapereader.

Chad, Chadless: A classification of paper tapepunch machines, referring to whether the chad orsmall paper circles remain as a part of (chadless) orare completely removed from the punched tape. Aquote: "The chadless tape does not wind well,takes up more space when wound and occasionallywill not read correctly if the little tabs of paper getstuck back in the holes." (Dan Nolan, RTTYJournal, February 1976, page 17.) However, thesepotential problems may be insignificant if a parti-cular chadless machine is priced right.

Clutch: A term used to denote that current iscontinuously flowing in the Teletype loop supply,uninterrupted by any data input. The clutch ormarking state is used to prevent the machine fromrunning open and producing nothing but mechan-ical clatter.

Converter, Terminal Unit (TU), or Demodulator: A

radioteletype (RTTY) term which indicates adevice that accepts the two audio tones, represen-ting mark and space, from the output of a receiverand converts them into current loop pulses fordisplaying characters on a page printer.

CR and LF: Carriage Return and Line Feed.

Demodulator: See Converter.

Frequency Shift Keyer, FSK: A radio Teletypeterm which indicates a device that converts thecurrent loop pulses from a keyboard or paper tapereader into audio tones. An amateur radio trans-mitter then converts these tones to radio wavessuitable for communications use.

Governor Motor: A nonsynchronous teleprintermotor, the speed of which is normally adjustedmechanically by viewing white strobe dots on therotating assembly through a slit shutter tuningfork. Some hams have built speed controls forthese machines, enabling electrical adjustmentfrom 60 to over 100 words per minute.

KSR: Keyboard Send and Receive. Refers to ateleprinter system which includes a page printerand a keyboard only.

Ham: A radio amateur.

Loop Supply: A DC power supply used to driveteleprinter selector magnets; capable of supplying20 or more commonly 60 mA at 130 to 260 VDC.Below 130 V, loop time constants can causedifficulty. Western Union telegraph loops usuallywork with 260 V.

Mark or "Closed Loop": A condition of steadycurrent flow in the teleprinter loop; see clutch.

MARS: The Military Affiliate Radio System,whereby civilian amateur radio operators, hams,assist the armed forces with message communica-tions, at the same time acquiring valuable trainingin military communications procedures. MARS isoperated jointly by the Navy, Air Force and Army.

PaperTapes: The narrow 0.375 in (0.953 cm) tapeis usually gum backed and is used with a stripprinter which just types messages on narrow tape.Western Union attaches strips of this tape to paperin their telegram operations. The wide 0.6875 inch(1.746 cm) tape is used with typing reperforators,chadless, and nontyping reperforators, chad type,which punch holes in the tape.

Perforator: A unit which can punch tape from anattached Baudot keyboard input only because theperforator operates from mechanical linkages tothis keyboard. Cannot punch tapes from an exter-nal current interrupting source.

Reperforator: Derived from receiving perforator.This unit can receive serial Baudot paperpunchingmessages from both the keyboard and an externalcurrent loop interrupter.

RO: Read Only. Refers to a teleprinter systemwhich includes a page printer only.

RTTY: Radioteletype: A form of amateur radiocommunications which uses teleprinter machinesfor transmitting and receiving messages via radiowaves.

Space or Open Loop: A condition of no currentflow in the teleprinter loop.

Stunt Box: A mechanical teleprinter attachmentwhich performs certain nonprinting functions orstunts. These may include turning on a light,switching from nonprint to print, automatic car-riage return and line feed, vertical and horizontaltabulation, backspace, two color ribbon, etc. Theseare rather complicated. Rube Goldberg contrap-tions, and are difficult to service.

Synchronous Motor: A motor which rotatessynchronously at a constant speed which is directlyproportional to the AC line frequency.

Terminal Unit, TU: See Converter.

Transmitter Distributor, TD, or Tape Reader: A

machine which senses the characters punched intoa paper tape and sends them automatically at aconstant speed over a teleprinter loop circuit.

Typing Reperforator or Tape Punch: A machinewhich punches Baudot coded chadless holes into apaper tape and prints the associated charactersright on the tape.

WPM: Words Per Minute.

100

to 130VDC in this application. The serialinput interface is an equally simple mini-mum component count circuit (see refer-ences 13 and 14).

There are two ways to input and outputthe serial Baudot data with this softwareapproach:

1. Use operating software which inputsand outputs Baudot directly, as in theBaudot Monitor and Editor programslisted in reference 20.

2. Use operating software which nor-mally uses ASCII input and output.However, provide additional code con-version lookup table software (see

"Sources of Baudot Software" below)and modify the original ASCII pro-grams to call these code conversionroutines. Therefore, serial Baudot isinput and output at the processor IOport. Obviously, if the programs are inread only memory and not program-mable read only memory, they cannotbe modified to take vectors to thesoftware conversion routines.Both approaches require the use of thetimed software described earlier.

An In Between Interface

Another processor to Baudot machine in-terface method might be called a hybrid ap-

SOURCES OF BAUDOT SOFTWARE

SOURCES OF BAUDOT HARDWARE

1. MITS, 2540 Alamo SE, Albuquerque NM87106. Selected programs from the AltairSoftware Library:

(a) =728752 by J R Scott, $2, 36 byte programtranslates some Baudot character codes toASCII equivalent.

(b) ---5-24-762 by Walter King, $2, 50 byteprogram loads object code from 5 levelpaper tape.

(c) =5-24-765 by Walter King, $2, 71 byteprogram punches 5 level object tapes whichcan be read by =5-24-762.

(d) =6-18-761 by James B Hansen, 215 byteprogram, title: ASCII to Baudot TranslateRoutine.

(e) =6-22-761 by Jim Wiggins, (1) 106 byteprogram, title: Tape Load — Octal TLQ, (2)186 byte program, title: Tape Dump —Octal TDQ, for Baudot Teletypes.

The prices shown assume membership, $10 peryear, in the Altair User's Club. An interestingnote is that MITS is accepting no more Baudotcode converter or Baudot paper tape punch andload programs into their library because it isoverstocked with these types of programs.

2. M6800 User's Group Library, Motorola Inc.Microsystems, 3102 N 56th St, Phoenix AZ85018. Reentrant ASCII to Baudot ConverterSubroutine, Astrobaud. Other Baudot relatedprograms may become available. A two yearmembership into this user's group is availablefor $100 or to anyone who submits an entry tothe Program Library.

3. Intel Corp, User's Library, MicrocomputerSystems, 3065 Bowers Av, Santa Clara CA95051. Paper Tape Conversion program in 4040language, converts 5 level paper tape informa-tion to ASCII 8 level paper tape. Other 4040and 8080 Baudot code related programs maybecome available. A one year membership inthe user's group is $100 or is available if aprogram is submitted to the library.

4. The Digital Group Inc, POB 6528, Denver CO80206. Software Package HAM-1, AmateurRadio Ham Cassette for 8080, includes pro-grams to send and receive RTTY Baudot, at60, 66 and 100 wpm; $5 for cassette plusdocumentation.

5. See references 22a, 22b, and 23 of thebibliography.

1. Processor Technology, 2465 Fourth St,Berkeley CA 94710. 3P + S IO Module, $125kit, $165 assembled, Altair/IMSAI plug com-patible. Includes serial IO ports under softwarecontrol, from 35 to 9600 bps for use with olderBaudot machines.

2. HAL Communications Corp, 807 E Green St,POB 365, Urbana IL 61801. MCEM-8080Microcomputer System, $375 assembled. Soft-ware monitor supports ASCII or Baudot code;optoisolator loop current driver and receiver.

3. Mini Micro Mart, 1618 James St, Syracuse NY13203. Code Converter Boards: (1) ParallelASCII to Serial Baudot kit =GPA-B, $34.95,(2) Serial Baudot to Parallel ASCII kit #TVT2540 - BSI, $34.95.

4. MITS, 2450 Alamo SE, Albuquerque NM87106. The Altair 680 microcomputer, $466kit, is listed as having a five level Baudotinterface option, an additional $42.

5. IMSAI, 14860 Wicks Blvd, San Leandro CA94577. Two of the IO boards available fromthis company offer Baudot machine compatibleserial output bps rates.

(DSIO 2-1, $125 kit, 75 bps minimum,compatible with 100 wmp machine such asModel 28s and property geared Klein-schmidts.

(2) MIO, $195 kit, continuously selectable from40 to 9600 asynchronous, compatible with60 wpm, 45 bps, Model 15s as well as allother speeds.

6. Southwest Technical Products Co, 219 W

Rhapsody, San Antonio TX 78216.

(1) ASCII to Baudot Converter kit, $24.50, PCboard, $4.35. Circuit presented in reference15.

(2) Baudot to ASCII Converter kit, $19.50, PCboard, $4.35. Circuit presented in reference16.

7. Polymorphic Systems, 737 S Kellogg, GoletaCA 93017. A Serial IO Option, $75 kit, can beadded to the Poly-88 microcomputer kit whichprovides a 50 bps minimum IO rate.

8. Ohio Scientific Instruments, OSI, POB 374,Hudson OH 44236. Model 412B Supercard isdesignated for Baudot Terminals, $129 kit,based on MOS Technology 6502 microproces-sor.

9. See reference 1 7.

101

proach, whereby parallel Baudot charactersare generated by the software. These charac-ters are presented to the data bus wherebusy and ready handshaking logic describedin the above hardware interface descriptionis used. In effect, the software performs thecode conversion or parallel 10 function andthe hardware performs the parallel to serialconversion and character bit timingfunctions.

A UART or similar circuit (see reference17) can be used to implement thesefunctions. The whole procedure operates inreverse when the serial Baudot characters areinput to the hardware portion of theinterface and presented in parallel form tothe data bus.

The Interrupt Driven Interface

These old surplus Baudot machines may

of course be interfaced to the processorusing an interrupt scheme, with prioritiesassigned to each Baudot device along withother system peripherals. Interrupt schemesare beyond the scope of this discussion sincethere are so many variations of software andhardware interrupt techniques, and theyvary according to the processor being used.Many, and possibly most, computer hobby-ist systems do not use interrupts at all.Usually in this class of system, either thereare few peripherals being used or the oper-ator has lots of time on his hands to WAITon the peripherals, or both. One examplewould be a system with a keyboard and pageprinter combination operating with monitorand debug programs.

For a system with several 10 devices andvery busy software, setting up an interruptscheme may become a matter of necessity. If

REFERENCES ON BAUDOT TELETYPES

Many of these references, especially the ama-teur radio magazines and books, may be availablefor loan from a friendly ham in your area. Someham operators have been known to hoard all of theissues of some of their type journals, such as HamRadio, CQ, 73, or QST magazines. It should beknown that a similar affliction has been found withmany BYTE readers . . .

1. RTTY Journal, POB 837, Royal Oak Ml48068, 10 issues per year, $.35 per issue.

2. RTTY from A to Z by Durward J Tucker,Corvan Publishing Corp, 1970, 214 pages, $5.Detailed information on operation, mechani-cal characteristics and maintenance of practi-cally all of the older Teletype machines.

3. The Teleprinter Handbook, first edition byD J Goacher and J G Denny, Radio Society ofGreat Britain, 1973, $14.95. Distributed inUS by Ham Radio Books, Greenville NH03048. An engineering textbook covering thetheory and practice of radio teleprinter equip-ment; 30 pages of pictures and wiring dia-grams of Models 15, 19, and a few pages onthe Model 28. Also covered are the design ofpower supplies, demodulators and Teletypetest equipment.

4. Specialized Communications Techniques forthe Radio Amateur, by the American RadioRelay League, 1975, 208 pages, $3. Chapter5: Radioteletype, 70 pages. A condensedoverview of many of the Baudot machines, atable of Teletype Gear numbers for Models14, 1 5 and 28, and many other basics.

5. The New RTTY Handbook by Byron HKretzman, Cowan Publishing Corp, 1962, 191pages, $3.95. Includes a brief history ofBaudot teleprinters and some equipmentdescriptions.

6. RTTY Handbook by Wayne Green, TabBooks, 1972, 320 pages, $6.95. Many basicamateur radio operating circuits such as con-verters, exciters and FSK circuits.

7. Shinsel, Vic: "RTTY Signal Generator," HamRadio Magazine, March 1971, pages 23 to 29.RTL version of RY generator circuit.

8. Dean, J A and Rupley, J P: RCA ApplicationNote ICAN-6267, "Astable and MonostableOscillators Using RCA COS/MOS Digital Inte-grated Circuits," 8 pages.

9. 777e TTL Cookbook by Donald M Lancaster,Howard Sams Inc, pages 152 to 153. Aparallel Baudot to parallel ASCII conversioncircuit is presented which uses 5 ICs including2 PROMs.

10. Ellsworth, Cole: "ASCII to Baudot Con-verter," 73 Magazine, February 1976, pages52 to 57. A 15 IC parallel ASCII to parallelBaudot code converter. Additional UARTcircuit required to obtain serial Baudot forteleprinters.

11. Hutton, Louis I: "Build This Exciting NewTVT," 73 Magazine, March 1976, pages 76 to83. Included is a Teletype current loopBaudot code to parallel ASCII converter fordriving a video terminal display, page 80.

11a. Hutton, Louis I: "Code Converter UsingPROMs," 73 Magazine, May 1976, pages 84 to86. Improved circuit using readily availablePROMs; refers to reference 11.

12. Andreasen, C Warren: "A Versatile TTYGenerator," 73 Magazine, April 1976, pages90 to 91. Circuit is given that counts from00000 to 11111 and converts to serialBaudot, thus generating a pattern of allBaudot letters and figures.

13. Whipple, Dick, and Arnold, John: "A VeryCheap IO - the Model 15," 73 Magazine, May1976, pages 77 to 80. Presents both softwareand hardware interfaces.

14. King, Walter S: "Interfacing the 60 mACurrent Loop," BYTE magazine, August1976, pages 96 to 97.

102

this is the case, information on interruptinterfacing techniques and hardware may beobtained from a variety of references,including microprocessor manufacturers'application literature or any of the excellentprogramming books or publications avail-able (references 23b and 26) which deal withthis subject.

Useful Miscellaneous Items

Cleaning an Old Teletype: In the course ofresearching for this article, I ran across anemployee of a national teleprinter refur-bishing house for Model 28s, 33s, and 35s,who offered some interesting suggestions forcleaning a Model 15. He said that thisprocedure could be followed if one obtainedan extremely dirty teleprinter "fresh" out ofa damp basement. The steps are as follows:

1. Thoroughly clean the machine withhot water. An ideal place for this is ata self-service car wash facility.

2. Force air dry the machine with an airgun from, for instance, one available atthe auto service station with the carwash.

3. Spray all parts with a light lubricantsuch as WD-40.

4. Lubricate as required with oil andgrease. Details of these procedures arecontained in references 1 through 6.Pay particular attention to lubricatingthe felt separating pads, which shouldbe saturated.

One thing I might add is to clean allelectrical contacts, especially the keyboard,after the above sequence. A standard pencileraser rubbed over the contacts until clean isan excellent way to accomplish this.

15. Smith, Roger L: "ASCII to Baudot," RadioElectronics, March 1976, pages 51 to 58.Corrections, April 1976, page 58, and August1976, pages 16 and 22. Hardware codeconverter.

16. Smith, Roger L: "Baudot to ASCII," RadioElectronics, April 1976 pages 57 to 59.Hardware code converter.

17. Pasco, Richard C: "Converter Lets ProcessorDrive Teletypewriter," ELECTRONICS,October 30 1975, pages 97 to 98. Simple 6 ICTTL circuit which accepts 5 or 8 bit paralleldata and converts it to serial current looppulses at any desired bps rate.

18. Reference Data for Radio Engineers, fifthedition, pages 35 to 40, table 24: "MooreARQ Code (Compared with 5 Unit Tele-printer Code)" and pages 35 to 38, table 22:"Timing of Five Unit Start Stop TeleprinterCodes."

19. Whipple, Dick, and Arnold, John: "Inex-pensive Paper Tape Subsystem: Using 5 LevelTape with Computers," 73 Magazine, July1976, pages 145 to 148. Includes listings ofpaper tape read and punch software forTeletype Models 14 and 19.

20. Whipple, Dick, and Arnold, John: "A BaudotMonitor/Editor System . . . program listing forthe 8080," 73 Magazine, August 1976, pages102 to 105. Uses the software IO described inreference 19. Also uses split octal ad-dresses and octal data notations.

21. Guthrie, R David: "ASCII/Baudot with aPROM," 73 Magazine, June 1976, pages 114to 119. Article title is a misnomer — actually aserial Baudot to parallel, or serial, ASCIIhardware code converter circuit is presentedfor any desired data rate.

22. The Computer Hobbyist Group {North Texas}Newsletter, 2377 Dalworth 157, Grand PrairieTX 75050.

(a) Volume 2, #4, April 1976, pages 7 to 13.

Contains listings of ASCII to Baudot andBaudot to ASCII conversion software forboth the 8080 and the 6800 by TomGentry, James Brown, and others on thenewsletter's "conversion committee."

(b) Volume 2, =5, May 1976, pages 7 to 11.Contains a listing of ASCII to Baudotconversion software for the F8 micropro-cessor by Harold A Mauch.

(c) Volume 2, #2, February 1976, "TTYInterfaces" by Harold A Mauch, pages 13to 15.

23. The Computer Hobbyist, POB 295, Cary NC27511. Back issues are $.65 each.

(a) Volume 1, #3, January 1975, pages 19 to21, "Interfacing a 5 Level Teleprinter" bySteve Stallings, software courtesy ofRichard Smith. Contains listings of anASCII to Baudot Translate routine, aTeletype Demo Program which generateslines of ripple pattern on the page printer,and a Baudot Teletype Output Routinewhich accepts Baudot characters andenables outputting in Baudot directly, ifcalled as a subroutine, rather than con-verting from ASCII to Baudot.

(b) Volume 1, #9, February 1976, pages 11 to13, "Interfacing the Altair 8800, Part 2"by Hal Chamberlin. Includes an excellentdiscussion of simple single device hardwareand software interrupts, vectored andpolled interrupts, and an example of akeyboard interface using the interrupttechnique.

24. Teletype Corp, 5555 Touhy Av, Skokie IL60076.

25. Nettles, Walter: "Instructions for HandOperated Typewriter Ribbon ReinkingDevice," reference 1, Volume 12, #6, page 16.

26. How to Use the Nova Minicomputers, by DataGeneral Corp, 1971, Section 2.4 "ProgramInterrupt." Contains a discussion of interruptservicing and priority and programming sugges-tions such as when to use interrupt.

103

Ribbon Renewing: When the black printribbon begins to fade or dry up, additionalink may be applied on the top and bottomof the ribbon to provide many more miles ofheavy duty use from a single roll of ribbon.Also, the printing is much darker and easierto read on both page printers and typingtape reperforators. Inks suitable for thispurpose include stencil ink, stamp pad inkthinned with wood alcohol (methanol), andmimeograph or duplicator ink thinned witheither naptha or turpentine; see reference25. One ham I spoke with bragged of using3-in-l household oil as a thinning agent.Regardless of which type of ink is used,apply new ink sparingly until you get theknack of reinking. Allow at least 24 hoursfor the ink to soak into the ribbon andpartially dry out before using on a printingmachine.

Increasing the Operating Speed of BaudotMachines: There have been many commentsin the hobbyist literature regarding theeffects of increasing the speed of the olderBaudot machines. Of the more popular unitssuch as Models 14, 15, 19 and 28, only theModel 28 and some Model 14s were actually

designed to operate at 100 words per min-ute. The other models were designed forslow speed operation and simply do not holdup well when run faster. Gordon White, the"Surplus Sidelights" columnist for CQ maga-zine, had these comments in CQ, August1971, page 87:

"It is possible to gear the old equip-ment up to turn 100 wpm, but partic-ularly the Model 15 and 19 pageprinters do not last long at 100 speed.The Model 14 typing reperforator willdo a little better, but still hops aroundwhen forced to run at 100 speed. TheModel 14 transmitter distributor ap-pears to serve adequately at 100 wpm,as does the Model 14 nontyping reper-forator, if kept well oiled."The older machines will run at 67 or75 wpm with a gear change ..."

The gear changes referred to are relativelysimple to achieve. Faster gear sets may beobtained from most of the suppliers ofBaudot teleprinters. Also, a full page table ofgear set numbers required for various speedson Model 14s, 15s, and 28s is shown on page111 of reference 4."

• Never Toggle in a BootstrapAgain

• Never Flip Sense SwitchesAgain

• Run Without a Front Panel

• Plug Into Backplane

• Use With Your Own ROM

• Completely Configurable

The Automatic Boot Loader

POWER-START

RMQ Systems' new Altair 8800-compatible POWER-START™ board is supplied with complete documen-tation and configuration information. Components are of the highest commercial quality, including double-sided printed circuit board with solder mask on both sides and silk screened legend, low-profile gold-inlay1C sockets, and gold-plated bus contacts.

POWER-START™ Kit (PS-2K) 165.00 Kit (PS-IK) with ROM 195.00Assembled (PS-2A) 265.00 Assembled (PS-1A) with ROM 295.00

To Order or for More Information:

RMQ Systems

Research G Development Division of

computer kits, inc.

the systems store1044 University Ave., Berkeley, CA 94710 (415) 845-5300

104

Continued from page 14

latter pending successful completion ofour present negotiations).

We carry an extensive library ofperiodicals (including those hard to getBYTE back issues) and texts related tomicro and minicomputers, hardware andsoftware. We have also acquired theassets and inventories of B & B BookService, plus their distribution rights.

Our associate store, Focus Scientificin Ottawa, I 60 Elgin St, (613)236-7767,began selling microcomputers in Decem-ber. It is currently following the growthpattern of our Toronto outlet.

We have been guests on a financialand business show on CITY-TV, and weare going to be doing a radio talk show(The In Toronto Show) on CHUM FM,with host Larry Wilson. We will alsobeing doing a series of television showson the Ontario Educational TelevisionNetwork with host Larry Wilson.

We arc currently negotiating withgroups in London, Ontario, andMontreal, Quebec, for "The ComputerPlace" franchises.

Stephen Pumple

The Computer Place

186 Queen St W

Toronto, Ontario

CANADA M5V 1Z1

BROADCAST AUTOMATION:DOING IT

I read with interest Mr Alvin's let-ter in the February issue about usingan Altair 8800a for program automa-tion. This is entirely feasible. In factHarris Broadcast Products in QuincyIL makes an automation system basedon a microprocessor. It's calledSystem 90.

At KEZK I am implementing acommercial traffic and inventory sys-tem with an Altair 8800a. If thingswork out it will eventually lie in withbookkeeping, but that part is still inthe future. Our system has 32 K bytes ofprogrammable memory, two Phi-Deckswith the Digital Group controller, oneNorth Star mini disk with the Shugartdrive and a PT VDM. Our printer is aDECwriter II. Most commercial businesssystems for broadcast are very expen-sive by comparison. If any other broad-cast people arc working on similar sys-tems I would like to communicate withthem.

Noel M Moss

Chief Engineer, KEZK Radio

1780 S Brentwood Blvd

St Louis MO 63144

BROADCAST AUTOMATION:A VOICE OF EXPERIENCE

I read with interest Mr Alvin's letterin February 1977 BYTE concerning thepossible application of an Altair orsimilar unit for use in a broadcast auto-mation system. As a beginning computer

hobbyist and as the salesman responsiblefor the western area lor Systems Market-ing Company/Sono-Mag Corporation ofBloomington IL. I have the followingcomments.

SMC, the company I work for, is oneof the leading builders of broadcast auto-mation equipment. Seven years ago webrought out our first computer operandsystem, a hard wired ferrtte core mem-ory unit with 2048 user addresses with24 bit words. We called it the DP-1 andare still making and selling it. It has anintegral, fully programmable real timeclock, LED displays, and its functions areprogrammed at a low level using num-bers. It may also be addressed from anexternal Teletype (110 bps) or computerinterface. Originally it sold for $16000and now in a much improved version is$12000. This may seem like "an arm anda leg" to Mr Alvin, but the cost covers allthe following:

1. The computer itself, core mem-ory, all electronic interface, anda mammoth power supply.

2. The clock boards, their program-ming interface.

3. The digital switching hardwarewhich provides a very sophisti-cated unit to control the broad-cast magnetic tape audio units, toprovide the correct responses toexternal human interrupts, and toprovide time code generationand logging ports for the FCCrequired alphanumeric logging.

A second unit, the DP-2, has been

introduced in the past two years. Thisis a 16 bit microprocessor with soft-ware and 2000, 4000, 6000 or 8000user instructions. Included with this unitis another microprocessor controlledreal time clock. Both of these units (DP-1and DP-2) are available with video dis-plays, digital cassette, the possibilityof floppy disks, etc. The DP-2 starts atabout $15000 with all the externalslisted above for the DP-1.

Since we have brought these unitsout we have found out several thingsabout the problem oI station control:

1. The systems are very expensiveto develop, requiring a lot ofexpensive human lime. There-fore they must be able to bemarketed in their original formsfor several years.

2. The level of operation must bevery simple and require little ifany training for the operatorssince radio stations usually cannotpay much. Computer languagesand sophisticated concepts areout.

3. Maintenance must be simple andsupport available since few, ifany, broadcast engineers aretrained in digital operations andsupport. Systems must be as re-dundant as possible and main-tenance is mostly by substitution.

We find more often than not thatradio stations do not supply an engineer

105

MERLIN is the beat ASCII/Graphicsboard now available for the S-100 bus. . . and at an unbelievable price!

Compare these features to any other

video interface:

ft 160H x 100V resolution bit mapping

graphicsft On-board ROM (Monitor/Editor)

optionft 40 characters by 20 lines, character

ROM generated (hardware)ft Keyboard interface (with power)ft Programmable modes and display

formatft Serial I/O port

ft Low power . . . only 600ma at +8Vft Extremely fast (uses DMA)ft Comprehensive User Manual

. . . 200psft American 60HZ or European 50 HZ

operation.

Designed-ln expandability means maxi-mum versitility at minimum cost.Add-on options now available (in kitform) Include:ft Super Dense Graphics

(M320-K) $39

ft Lower case characters

(LC) $25

ft Serlal-to-parallel expansion Kit

(MSEK-K) $45

ft 1500 Baud (software) cassette

interface kit (MCAS-K) $29

ft 2K x 8 Mask ROM; graphics,

cassette, & extended editing

software (MEI) $35

ft 2K x 8 Mask ROM/256 RAM;

MonitorEditorSoftware(MBI) ..$39

The MBI ROM software Is designed toallow turnkey operation and sophisti-cated editing and scrolling.

Ask to see a demonstration of MERLINat your nearest computer store. Manydealers now stock MERLIN and there isnothing like a hands-on demo for reallyevaluating a product. We know you'llbe sold.

MERLIN Kit with Manual $269

MERLIN, assm'd& tested $349

MERLIN User Manual $ 10

For fast information, write us direct!MC and BAC accepted.

MiniTerm Associates, inc.

Bo. 26B Bedtatd. Ma,

1730 16171 648.1200

I

ITM

IIU I CrilMLG

MICROCOMPUTING FOR HOME AND THE SMALL RUSINESSMAN

The professional publication bringing microcomputing technology to the hobbyist, small businessman, educator,engineer and student. Every issue edited to bring technology and people together in the simplest manner.

INTERFACE AGE is packed with

HARDWARE ARTICLES — Product profiles, comparisons,applications, modifications and construction pro-jects.

SOFTWARE ARTICLES — Microcomputer developmentsoftware, short software routines, applicationsoftware, off-line software storage formats, softwarecommunication standards and access to themicrocomputer software depository for all INTER-FACE AGE readers.

TUTORIALS — Fundamentals of micro processors, basics formicrocomputing, professional to technical transitioninformation, understanding software, elementarymath for computing.

• NEW PRODUCTS — Manufacturer profiles and latestproduct releases.

USER COMMUNICATION - UPDATE - devoted toclub and organization announcementsand activities. — LETTERS TO THE

EDITOR — Reader forum for expressionof opinions and feedback on articles andfeatures.

i MICRO-MARKET/FIFO FLEA MARKET - Low cost/nocost advertising for the newmarketeer/garage sale enthusiast.

If you need to know how to get started in microcomputing or need the valuable software onceyour system is completed then INTERFACE AGE is a must for you.

Don't Delay — Subscribe Today!

r

INTERFACE AGE MAGAZINE

"1

P.O. Box 1234Cerritos, CA. 90701

Name.

12 Monthly Issues:

$10 U.S., $12 Can./Mex.,

$18 International

□ CHECK

D MONEY ORDER

Address.

City

Country .

State-

Zip.

I

MAKE CHECK PAYABLE TO: INTERFACE AGE MAGAZINE

AYABLE TO: INTERFACE AGE MAGAZINE

with the simplest scope, logic probe ormeter. Therefore to a trained computertechnician our equipment quite oftenlooks childishly simple. I hope so, sincethat means we have accomplished ourpurpose.

I see no real reason (given an enor-mous amount of free time which you donot value) that a microcomputer adver-tised in BYTE could not be programmed,the digital to analog controls built and theinterface to the other specialized broad-cast playback gear designed and devel-oped. It only took three and half yearsfor us to get everything done on theDP-2 unit to get it on the market.

I don't want in any way to denigrateany ambitions to produce a new anduseful controller for broadcast automa-tion. I think that creativity of any kindis laudable and should be encouraged.But please understand the realities ofwhat you are getting into. The old con-trol unit you are operating with nowprobably cost at least $5000 twentyyears ago. It is not capable of a fiftiethof what the least expensive new com-mercial units can do. To replace thatunit with a new one amortized overfive years with financing would costabout $300 to $350 per month andwould be good for another 20 years.

If you decide to go ahead on yourown, please let me know. Maybe I cankeep you from some of the time-con-suming blind alleys that we sufferedthrough. If you don't, let me hear fromyou anyway.

Pete Charlton

491 Elbow Ct

Weatherford TX 76086

AH PUN, MY WORD

I would just like to say that Icompletely support your position on theforms of humor that Mr Kramer wasobjecting to, though Deborah Luhrs'pun-ch line almost reversed my opinion!I feel that to remove this humor wouldbe to send BYTE a (very) small incre-ment toward the level of the computermagazines over which it presides; afterall, everybody needs a little pun in life.

Seriously, I congratulate you on yourtremendous accomplishments in creatingand improving BYTE; I wish I couldthink of something that needs help, buteach issue seems perfect, yet they keepgetting better. Keep up the good work(and the presses punning).

Richard Zulch

Assistant to the Director

Computer Science Dept

Redwood High School

Larkspur CA 94939

/ always was skeptical when theauthoritarian and pontifical humanitiesteacher I had in my high school statedthe profound truth that "the pun wasthe lowest form of humour. " How couldhe simultaneously say that and expoundon the glories of William Shakespeareand a whole host of later, but not

necessarily greater, punsters in Englishliterature? . . . CH

MORE ON PUNS AND PUNDITS

I agree with Mr Kramer's letter inthe January issue. Oh pun my word I do.Are we not safe in our 'ohms from suchpundits as he criticizes. I am currentlyworking on a plan to punish punstersbefore they make a hash of our memo-ries. IC many possibilities. We shouldmake them use odd addresses such assubmarines, where the subroutine willchip away at their systems; make themqueue for train buffers to ride on asGilbert suggested; RAM them into oldfashioned PROMS; load them intofloppy diskos to pick up a baud para-doxies. Some even call me a punster,GOTO!

All seriousness aside, I haven't evennoticed the puns Mr Kramer complainsof.

I compliment you on a fine maga-zine. I learn something from everyissue, and haven't found a really unin-teresting article yet. Keep up the goodwork. One of these years, time andmoney permitting, I'll have my ownmicrocomputer and will appreciateyou even more.

Robert A Taylor

POB 638

Gate City VA 24251

KUDOS

I have been programming for manyyears—for the government, for privateindustry, on big IBM 370s and nowmicroprocessors; but, I have never pro-grammed for myself. I never really knewwhat personal computing was until Iread your magazine and now I amextremely excited about the prospects.

I am very pleased with the effortyour magazine is making to bring theworld of software to the readers. Youare building a source of reference for theestablished hobbyist, while your articlesare providing a fine base for beginners.Hopefully, with this knowledge, peoplewill realize the computer is not thecomplex social obstacle or menace tothe human race, as was once thought.

Without further adieu, I welcome allyou hobbyists to the wonder world ofsoftware and may it bring you all manyhappy days in return.

Kevin Stumpf

Proprietor

Computing Elements Development

277 Hazel St

Waterloo, Ontario N21 3P1

CANADA

WHERE?

I really enjoyed November's BYTE.The article by Tom Buschbach called"Add This Graphics Display to YourSystem" is the second article in yourmagazine to mention Don Lancaster's

107

SUPER DENSE

GRAPHICS

320 Horizontal by 200 Vertical

Y-#"aXC0S<2lX/b)

••.•1. kM2.BC

IF YOUR COMPUTER • w -CAN'T SMILE <OftPLOT) IT PROBABLYHAS HERLIH DEFICIENCY VANEMIA. \ XXS^y

(EQUATION PLOTTED HITH BASIC)

The MERLIN Super Dense add-on kitprovides maximum resolution at aminimum cost. In fact, MERLIN withSuper Dense has more capabilities thanany other S-100 bus video interface atany price!

Once you've seen 'Super Dense'graphic resolution you'll know there isnothing to compare it to . . . short ofspending over $600 . . . and even thenyou'll not have all of the capabilities ofMERLIN with 'Super Dense'.

Super Dense provides true bit-mapping. Each and every point on thescreen Is controlled directly by a bit inmemory. (Requires 8K of systemmemory.)

ROM character-graphics looked goodfor a while; then came MERLIN'S 160 by100 bit mapping graphics; and now . . .

320 by 200 bit-mapping graphical I!If you're looking for a graphic display,MERLIN with Super Dense Is the bestthere is. And If you hadn't consideredgraphics or thought it was out of yourprice range, consider what you coulddo with 320 H by 200V graphics and foronly $39 extra.

The Super Dense add-on kit to thepopular MERLIN video interface is nowavailable with off-the-shelf delivery.

M320-K, Super Dense Kit $39

M320-A, Super Dense Assm. . .$54See MERLIN ad on previous page.

For information fast, write direct, orsee 'Super Dense' at your nearestcomputer store.

MC and BAC accepted.

MimTerm Associates, inc.

11730 (6171 648-1200

TV Typewriter Cookbook. Do you hap-pen to know where I can purchase thisbook?

Glenn R Johnson

6445 SW 196th Av

Aloha OR 97005

Yes . . . Order it for $9.95 fromBITS. For the address see the advertise-ment in this issue.

JOHN PARKE, M. D.

Mtdical and Surgical Urolog,

Office: 717 A Avrnuc N. B.

Phona 3fiJ ■ -USA Day or NiBr,[

110 I

B

Addrt-

Utnl wiih DtuK Nj.

— Utnl Wuh Drug Namr — / . U-

V.U 36*. st^l YT>V\ iv,fcn"r*

2;

it

*T

H£-<

2Z.T-X L^ (V<- Ht

A THANK YOU FOR TUTORIALS

Because I am a college student, Inever find the time to finish a copy ofBYTE before the next copy arrives inthe mail. That causes some frustrationbut cannot be helped. The real frustra-tion is not understanding many of thearticles that I do have time to read.

My knowledge of computers is limited tothe programming I have done over theyears coding BASIC and FORTRAN,although I do pick up some tasty bitsof information from BYTE. When I findan article such as "The Types and Usesof Direct Access Storage" by Curt Hill,(page 60, January 1977, BYTE] Ipositively salivate! Excellent subject;well presented. Thank you, Mr Hill!I am sure that there are many otherslike me who want lo understand com-puters before diving headfirst into highlydetailed, sophisticated jargon. Pleasecontinue to keep us in mind from timeto time by presenting other articles likethe above mentioned one. Continue toreward potential writers out in BYTEcountry for their contributions. Mostof all, publish! One day, when I havelearned more about computers andperipherals, I will pull out my backissues of BYTE and really appreciatethem.

Michael Craig

POB 895

West Acton MA 01720

On behalf of our readers, we'realways looking for good tutorial articleson subjects in computer science, art andpractice. Your note of appreciation forCurt Hill's article is one of the verypersonal profits to be derived fromwriting such an article.

A GOOD EXPERIENCE

In a new industry, such as the hobbycomputer industry, new companies al-ways seem to pop up overnight. Youkeep hearing stories of problems, delays,corrections, poor documentation, etc. Ieven recently purchased a "burned inand tested" memory board with two ofthe 2102s in their sockets backwards!There are, of course, many supplierstrying hard to establish a good reputa-tion. I would like to share my experiencewith one such company.

Recently I purchased an assembledCL2400 Real Time Clock Board fromComptek in La Canada CA. I called inthe COD order and received it the sameweek. I found the board to be of highquality and professionally assembled. Itwas obviously tested as they even en-closed the TTY printout of the test runon my unit. The documentation wasthorough including software in bothbasic and machine language, explana-tions, instructions, full troubleshootingroutines, parts layout and schematics.

Now time to hook it up lo mymachine. The unit requires one wire tobe installed from the +15 V supply tothe mother board to provide the timingto the clock. It was an easy task thattook less than five minutes. I then firedup my Altair and tried the program butwith no luck. Then I tried the trouble-shooting routines but was still stumped.

6800 OWNERS UNITE!

FREE YOURSELVES FROM THE BONDAGE OF SLOW CASSETTE I/O.

LOUDLY PROCLAIM YOUR SUPERIORITY OVER YOUR 8080 NEIGHBORS

AND THE Z-80 SUBCULTURE. JOIN THE BFD-68 REVOLUTION.

Our Basic Floppy Disc System (BFD-68) must, in all mod-esty, be called superb. It comes completely assembledwith a disc controller that is plug compatible with theSWTPC 6800. The cabinet and power supply are capableof handling 3 Shugart Mini-Floppy Drives. One drive isincluded in the basic system price of $795 and otherdrives may be added easily at any time for $390. Or, youmay save money by ordering a dual or triple drive sys-tem initially. The price for the BFD-68-2 is $1169 and forthe BFD-68-3 triple drive system $1539.

Remembering that we are prone to understatement, wemust say that while the BFD-68 hardware is superb, thesoftware is even better. Our Disc Operating System pro-vides the following advantages over most other systems.

• ANY NUMBER OF FILES MAY BE OPEN (IN USE) ATONETIME

• THE NUMBER OF FILES AND SIZE OF FILES IS LIM-ITED ONLY BY THE SIZE OF THE DISC

• MERGING FILES REQUIRE NO EXTRA DISC SPACE

• NO WAITING FOR THE DISC TO RE-PACK

• LONGER DISC LIFE- MORE EVEN DISC WEAR

NEED A FULL SIZE FLOPPY?

Our P-38-FF is a plug-in interface card to the ICOM FrugalFloppy™. It includes all the features of the P-38-I plus one 2708EPROM containing the ICOM bootstrap software. Just plug theP-38-FF into your SWTPC 6800 and your ICOM into the P-38-FFand you're ready to use the Frugal Floppy and ICOM's 6800 soft-ware package. Price $299.

Our P-38 is an 8K EPROM board containing room for 8 2708's.Or, you may use it to hold up to 7 2708's plus your MotorolaMikbug or Minibug II ROM. The P-38 addressing is switch select-able to any 8K location. Price $179.

The P-38-1 contains all the features of the P-38 plus an interfaceto the Oliver Paper Tape Reader and our EPROM Programmer.Price $229.

The PS-1 Power Supply Kit provides plus and minus 16 voltsrequired for the P-38 series boards. Also, it allows a wiring mod-ification to be made to the 8 volt supply that will increase itsoutput by one volt. Price $24.95.

Our M-16 is a 16K single power supply STATIC RAM memorysystem. The M-16 is fully buffered and requires only half thepower of a similar size system using low power 2102's. With theM-16, you can expand your system to 48K and still have roomleft over for one of our EPROM boards. Price $595.

ALL OUR PRODUCTS EXCEPT THE PS-1 ARE COMPLETELY AS-SEMBLED. AVAILABLE AT MANY SWTPC DEALERS OR FROM USBY MAIL. BANKAMERICARD AND MASTERCHARGE WELCOME.

SMOKE SIGNAL BROADCASTING

P.O. Box 2017, Hollywood, CA 90028

108

A call to California brought a returncall from Ken Finsler of Comptek. Whatevolved was two more calls with Kendoing a long distance check up of mysystem using me at the scope 3,000 milesaway. It resulted in finding a bad 7400that handles the ready line on myprocessor board. Since this was the firstboard that required a wait cycle itshowed up the bad chip that may havebeen faulty from when I built my mainframe.

The real time clock works perfectlynow and does everything promised withease. I offered to repay Ken for thephone bills as it wasn't even their fault,but they refused. Obviously they lostmoney on my sale but they still bentover backwards to make sure I washappy.

It's reassuring and a pleasure to dealwith ,i small company such as Comptekwhich cares about the customer as muchas the "buck." I hope that you can printthis letter so that the people readingyour magazine can share my goodencounter. It seems the least I can do torepay Comptek for their efforts.

Gary Cooper

Vice President

S Lachman and Sons Inc

College Park MD 20740

ON TECHNOLOGICAL TRENDSAND SURPRISES

Your editorial, "Caught by Surprise,"in the December 1976 issue, page 6,makes many pertinent points that someeconomists and certainly Ayn Randlibertarians have been pointing out foryears. Modern day large technical indus-tries as I know them I would placesomewhere between zoos and three ringcircuses with technical creativity andinnovation the least of their concerns.Having been associated with such placesfor long enough that I consider mycomments charitable, I always foundthat you end up with a corrupt, incom-petent bureaucracy whose only goal istheir survival — al whatever the cost.Such environments tend to filter out thebetter people, hound them out, or des-troy them creatively and psychologi-cally. Now, to expect the entrepreneuralact to arise from such shambles is beg-ging the ridiculous.

There have been singular studies donein the very recent past about exactly thissubject. I cite: M F Wolff, "The R and D'Bootleggers': Inventing Against Odds,"IEEE Spectrum, July 1975, pages 38-45;A Shapero, "The Displaced, Uncom-fortable Entrepreneur," PsychologyToday, November 1975, page 83. Tworecent books exist covering the sametopics: R Cornuelle, Demanaging

America, Vintage Books, New York1975; and S L Brown, et al, The Incredi-ble Bread Machine, Ward Ritchie Press,474 S Arroyo Pkwy, Pasadena CA, Octo-ber 1974.

In the broad sense, personal com-puting, and the activists and entre-

preneurs associated with it, have recon-firmed the possibilities in a pluralisticsociety with at least some remnant ofcapitalism. To be in the midst of suchevents says everything is not hopeless —IBM cannot tie Digital down nor Digitalthe smaller guys - even though without adoubt each would like to. What we seegoing on now should provide hope forthe individual.

Richard L Coleman

554 Springs Rd

Bedford MA 01730

REGARDING THEANTI-TECHNOLOGIST MENTALITY

I am writing this, my first letter to aneditor, in response to your December1976 editorial, page 6. In that editorialyou spoke about the growing belief thatAmerica is losing its technological edgeover the rest of the world. I would liketo add my own observations to yours.

At present I am a mathematics majorand work full time at Stanford's LinearAccelerator Center. I have spent thelast 8 years in the electronics industry.But it was not until I reenetered theuniversity environment that I first heardpeople speak out against technology.One has only to sit in on any collegecourse in the humanities to hear thegrowing choir of voices that rave atlength against technical advance. Themost commonly heard complaints are:inhuman, impersonal, unaesthetic, de-structive, etc.

Unfortunately, technologists, physi-cal scientists and mathematicians do notanswer these charges, much of the timebeing completely unaware of them.Compounding this is the fact that theirliterature is not widely disseminated orinviting to the untrained. Rather, it isthe very people who claim technologyto be evil who are more and moregetting their views widely published.

How long can American hold itslead when its young technologists aremade to feel as social criminals? Wheneverywhere they look they sec them-selves portrayed as dupes of a tyran-nical system?

It is not against the government thatwe should fight, but against the growingphilosophy of our age: a philosophy thatcalls for a return to the middle ages. Itis the nature of a culture's philosophythat determines the strength of thatculture. If we, the technologists, give upby default, who will be to blame?

K P Slattery

460 Auburn Way #18

San Jose CA 95129

Appropos your comment is thefollowing quotation from Robert Hein-lein's science fiction novel, The DoorInto Summer.

. . . despite the crapehangers, romanti-cists and anti-intellectuals, the worldsteadily grows better because the humanmind, applying itself to environment,

109

Made possible by the designed-inexpansion capabilities of the impres-sive MERLIN Video Interface.

Aside from general purpose uses, thedesigners at MiniTerm anticipatedGraphics and Graphics games and theproblem of control interfacing. TheMSEK (MERLIN Serial Expansion Kit)provides:

Three parallel Input portsThree parallel output ports

These can be used for interfacingjoysticks or game controllers or parallelI/O devices. And the price can't bebeat! The MSEK mounts inside yourkeyboard and connects to MERLINthrough the keyboard cable.

Also available from MiniTerm is thefirst real raster graphics "Space War"game for the personal/hobby market.

"Space War" gives the user control ofrotation, acceleration, and firing ofmissiles for two space ships. Whenused on the MERLIN video interfacewith 'Super Dense' add-on option (320 x200) the game provides more excite-ment than any BASIC version of "SpaceWar" or any of the standard TV games!

A delux version of "Space War" is alsoavailable which allows selection of shipdynamics to simulate cars, tanks,boats, etc. and allows the user to drawhis own 'ship'.

Space War (SPW) $25

Delux Space War (DSPW) $35

(Add suffix-T forTarbell tape, or-P for

INTEL hex paper tape.)

A complete source listing is availablefor an additional $10 for either game.

Write for full description, or better yet,play a few rounds at your localcomputer store. But be prepared tostay a while. There is likely to be aline and you may become addicted.

MC and BAC accepted.

MiniTerm Associates, inc.

in. JfiS Bedford. Mass 01730 (617) 648-1200

-

END FRONT

PANELFIDDLING...Use a

JUMPSTART

4KRfiM

With a )UMP STfiRT 4K RAM

board in your Altair/IMSAI,the system will jump to anypreset byte of memory afterpower-up or reset. Never tog-gle a jump to your monitor orbootstrap again! Just power-upor hit reset—JUMP STfiRTautomatically transfers con-trol to the selected address.The JUMP STfiRT 4K RAMboard has these standardfeatures:

• 4K 450 ns low power RAM

• fully buffered

• DIP switch address selection

• memory protect with POC

• battery backup connector

• fully socketed

• disabled during INTA

• optional wait state

Prices:

Kit $145

Assembled 190

Call toll-free anytime to

place credit card orders:

800/648 5311

Prepaid mail orders shipped postpaidin USA. California residents add 6%sales tax.

MICROMATION INCORPORATED

524 UNION STREET

SAN FRANCISCO, CA. 94133

415/398-0289

Dealer inquiries invitedCIRCLE NO. 242

makes it better. With hands . . . withtools . . . with horse sense and scienceand engineering.

Most of these long haired belittlerscan't drive a nail nor use a slide rule. I'dlike to invite them into Dr Twitchell'scage and ship them back to the twelfthcentury — and let them enjoy it.

But I am not mad at anybody and Ilike now . . .

The anti-technologist mentality is ananti-people (therefore, inhuman) mental-ity; for the whole reason for technologyin the first place is to seek new ways toimprove and expand the options open topeople. Hyprocrisy is rife when peopleuse the fruits of technology whilecondemning the means of achievingthem.

GETTING BAUD-Y

The term "baud rate" is indeed anabomination. But like "ain't," it is anassimilated abomination. And I'm not sosure it's all wrong.

Here is a line verbatim from Proc-essor Technology's manual for the 3P+SIO module: "The baud rate can be setfrom 35 to 9600 baud." I suppose thewriter could have said, "The baud can beset from 35 to 9600." The originalversion lias some hope of being under-stood by a reader who really didn'tknow what "baud" meant, but thesecond version has little such chance.

It's too bad the term baud hasbecome mysterious. All it means is howmany times per second can you changethe state of the signal line. If the line hastwo possible stales, eg: current or nocurrent, then the signaling rate in baud isthe same as the information rate in bitsper second. If your line has four possiblestates, say four different voltages, theneach state change transmits two bits ofinformation; and so in this case thesignaling rate in baud is only half theinformation rate in bits per second.Simple, ain't it?

Jack Dennon

1157 SE 2nd

Warrenton OR 97146

No, the improved version should havebeen: The data rate can be set from 35to 9600 bps; since as you point out, thetwo are identical for binary states.

APPALLED

I have been reading your excellentpublication for a few months now, and Iam appalled by the amount of obsoleteTTL being used. The most flagrantexample is the 7475 quad D latch (andthe 74100 octal D latch). These circuitsare a poor choice for almost all appli-cations, due to their excessive inputcurrents on both data (2 TTL loads perinput) and clock (2 TTL loads per latchbit, or 4 TTL loads per 7475 clockinput, or 8 TTL loads per 74100 clockinput), and due to the lack of a directclear input. The high input currentsforce the use of buffer gates to drive the

clock inputs, which are the wrongpolarity for TTL decoders anyway. Thelack of a direct clear input means thatperipherals such as tape drives come onflying, and must be idled by software (adirect clear input would permit a simplepower on reset circuit to force the tapedrives to come on idle). This is ridicu-lous; there are many better devicesaround:

1. If you don't need the Q outputs,any presettable counter can beused as a 4 bit latch to get lowinput currents, a direct clearinput, and a load input of theproper polarity for TTL addressdecoders. Examples are:74LS197, 74LS193, 74197,74193, 74192, 74196, etc. Load-able shift registers can also beused, such as 74 95 or 74LS295.The Intel 8212 can be used, as itis an 8 bit latch intended for useas an output port. The 74LS174or 741 74 can be used to get 6 bitsin a 16 pin package; the 174behaves like the 175 discussedbelow, without Q outputs.

2. If you do need the Q outputs, usethe 74LS175 or 74175 quad Dedge triggered flip flop. This haslow input currents (especially theLS version), and has a direct clear.However, the 175 lacks the trans-parent pass through feature of the75. The 75, if the clock is heldhigh, connects its inputs to itsoutputs, and the outputs followthe inputs as long as the clock isheld high. The 175 is an edgetriggered flip flop, not a latch, sothe 175 outputs can change stateonly on the rising edge of theclock. For output port latches,the flip flop works just as well.

To repeat, use the 7475 or 74100only if you need both the D latch (asopposed to D flip flop) function and theQ outputs, and you don't need a directclear function.

Any TTL circuit which does not havepower and ground on the coiner pinsshould be suspected of being obsolete, asit may have been designed before theDIP package was developed, and youshould look for newer circuits whichmay do the same job much better. Notethat many circuits do jobs not hinted atby their names. For example, manypresettable counters and shift registerscan be used as latches. Also, multiplexers(especially the 74LS257 and 74LS258)and decoders can be used to replace logicgate arrays.

The Tl book Designing with TTLIntegrated Circuits is a good introductionto TTL, but it is five years old. Somesections are now obsolete. For example,the section on variable modulus counterswas written before the advent of the74163 fully synchronous counter. The74163 has synchronous load and clearinputs, and can be used to makecounters without the glitches and tran-sient states inherent in counters built

110

around ripple counters like the 7493.

The only real cure Tor software theftis to make the software legally availableat a price comparable to the cost ofmaking an illicit copy, especially sincehobbyists are chronically short ofmoney.

Peter Traneus Anderson

103 N Union St

Burlington VT 05401

PS: Would you like to know some waysof expanding an 8080's instruction set?In a recent issue of Electronics, it isclaimed that some 6800 processors willrepeatedly increment their address lines,in response to a 9D op code. Are thereother hidden instructions in variousprocessors?

The new edition of The TTL DataBook for Design Engineers Is now out,and among other things it documents animpressive improvement in the range ofavailable standard TTL parts from thatsource. [It's now available from ourbook service, BITS Inc],

Regarding use of older parts, there isone main point worth making: I can readthe new TTL data book and drool aboutall the new parts, but as an experimenterI have a lab inventory full of partsacquired over the years, many of whichare quite serviceable if not optimal stateof the art. I don't wire up ALUs withNAND gates, mind you, bat if I need alatch and have a 74100 on hand but nostate of the art version of this part, I'lluse the 74100. An experimenter's lab isnot a production shop. Eventually, theearly 7400 series parts will go the way ofDTL and RTL before them, but apractical attitude dictates that if the partworks, it is TTL and if wiring for thingslike extra clock buffers is not excessivecompared to a newer part, why not useit?

Regarding expansion of instructionsets, it is a neat hack to try out all thevarious unimplemented operation codesand see what happens. However, usingsuch codes should be done with knowl-edge that they may show up in newerversions of the processor implemented indifferent ways. The manufacturers arenot about to be bound to software andhardware compatibility with instructionsthey don't acknowledge to officiallyexist.

SEVERAL VOTES FOR "THEMES"

1 don't often write letters to theeditor, but I just finished reading withsome interest and amusement Mr Eden'sletter in the December issue. I sayamusement because besides having anMSEE I have been an amateur radiooperator for about 25 years and I justgot through reading a similar letter froma ham in a ham magazine. The ham wascomplaining about the inclusion of com-puter articles in an amateur radio maga-zine and using most of the same argu-ments that Mr Eden used.

It should be obvious thai not allcomputer hobbyists are hams and not allhams have any interest in hobby com-puters. There are, however, enough withinterests in both fields to warrant inclu-sion of ham oriented articles in com-puter magazines and computer orientedarticles in the ham literature.

I, for one, am not particularly displayoriented at this time and so did notspend a lot of time with the Novemberdisplay issue. I have, however, more thanmade up for that issue with articles inother issues and certainly would notwant to deprive those who are interestedin displays of the excellent material inthat issue.

To conclude, there are a lot ofdifferent interest groups in this newhobby of ours and I think you are doingan excellent job of presenting material ofinterest to all . . . keep it up.

Bill Hosking W7JSW

8626 E Clarendon

Scottsdalc AZ 85251

AN ORIGINAL HOMEBREWER

I must be one of the original home-brewers. One day in about 1956, havingread a little Norberl Weiner, and havingjust discovered what number base 2 wasall about, I started toying with the ideaof designing a digital computer just forfun. Since I knew nothing of electronics,I settled on the idea of using 4PDTrelays for all logical machine elements. Ifelt that if I got the logical design down,it could always be implemented in moresophisticated hardware later on, on akind of one for one substitution basis.About 6 weeks later, I found myselfsurrounded with literally hundreds ofcircuit diagrams, black box diagrams,tables of nomenclature, and a string ofFs for my term in college.

I actually built (from about 80 pin-ball machine relays) a crude 6 bit adderwhich would occasionally add two num-bers correctly. My machine had a frontpanel that had an astonishing resem-blance to an Altair 680 front panel (in1956!). But behind the front panel,things were in pretty sad shape: totalmemory, two 6 bit words. Total instruc-tion set: A+B, with some tentative pro-visions for A*B. System reliability:about 50% (meaning one righl answer intwo).

Nevertheless, it was for me an im-mense victory. I had, on my own,examined some of the notions essentialto machine operation, such as parallelversus serial data, synchronous versusasynchronous, carry bit propagation, andso on. I had also assimilated some notionof the thousands of man years of hardwork, levels of miniaturization, technicalbreakthroughs, and so on that lay be-tween my machine and a practical scien-tific engineering desktop system. (Iwould guess that the average four func-tion calculator could have been imple-mented in my relay hardware in avolume no larger than, say, your average

111

They can transform a hobby computerinto a professional, useful tool.

But why pay $300 for one? TheMERLIN Video Interface is also a ROMMonitor board. The optional 2K x 8MBI ROM Monitor/Editor is availablefor only $39.

The MERLIN Monitor provides com-mands for turnkey 8080 or Z80operation and program debugging andthe Editor is the best there is. AnyBASIC or user program is compatiblewith the MBI software.

And now MiniTerm introduces theROM/EROM kit so that you can putthe rest of your operating system andgeneral purpose routines in ROM forincreased ease of use and reliability.

Just Look at these features:

ft Power-on jump to any 1K block

ft Holds eight 2708 EROMs

ft Bank select feature

ft S-100 bus compatible

ft Wait state logic

ft Addressable to any 4K block

And it's only $89 in kit form!

So write or buy your operating system— then optimize it for your specificneeds and put it into ROM where it willalways be available and yet changeablewhen necessary.

MiniTerm will also provide 2708s for$40 and will introduce its inexpensive2708 programmer next month.

Once you've had or used a system withgood ROM operating software (Moni-tor, Editor, Relocatable loader) you'llunderstand why ROM boards arebecoming so popular.

But don't spend more for ROM boardswith extra goodies when all you need isa board to hold your ROMs and toprovide power-on jump. Buy theMiniTerm ROM/EAROM kit for only$89.

For more information fast, write direct.

MC and BAC accepted.

MiniTerm Associates, inc.

, 268 Bodfoid Mass 01710 .f.1 ?■ 648 120H

I

..........

Microprocessor

Quay 80MPS.

For serious

hobbyists*

Quay 80MPS is nor designed for thecasual hobbyisr. Only if you're seriousobour your personal compuring,should you find ouf obour Quay80MPS's features, capabiliries, andoprions. Only if you wanr fo break freefrom hobby-class microprocessors andenrer a great new world of sophis-ticated computing experiences,should you get into rhe Quay 80MPS.

Features

D Single PC board, 16 pin dip connectors' (no costly backplane or edge con-nectors.)

D Z-80CPU. 158instruaions, 2.5 MHz clock.

D 4K dynamic RAM. Expands to 16K onboard (Z-80 refreshes w/o loss of thru-put).

□ 1K UVEPROM monitor. Inspea, alter,dump, and toad memory; set break-points; trace and single-step debugging;handles serial I/O.

D 7 additional UVEPROM sockets.

D 4 8-bit parallel I/O ports. Vectored in-terrupt (2 Z-80 PIO's, expands to 4).

D 1 socket for Z-80 4 channel countertimer.

a 1 UART. R5232 & 20 ma interface.

D UVEPROM programmer (2708).

□ Fully buffered address, data andcontrol.

Quay 80MP51s $695, assembled andtested. Send for complete details. Orfor fast action, Call 201-681-8700.

Masrercharge ond DankAmericard accepted. COD with1/3 deposit. NJ. residents odd 5% sales tax. Price doesnot include shipping and handling.

Dealer inquiries invited.

P.O. Box 386, Freehold, NJ. 07728.Phone: 201-681-8700

supermarket.) I resolved lo slay oui ofthe computer business until some otherfellows worked oul the details, and Ireturned to my studies lor an ME.

Well, I guess those other fellows didit. We have at the office a BASICfirmware calculator/computer system(HP 9830) that exceeds my wildesl I9S6dreams, and I'm spoiled rotten . . . nomachine language for this kid. No carddecks for overnight batch on the Cor-porate Monster . . . and the inevitablecore dump in the morning. No more fullmornings wasted trying to get the line upon the time share terminal. Sure, calcula-tor based BASIC systems are slow inprocessing, but they more than make upfor it in programming/debugging timeand ease, plus the fact that every nightof the week has 16 hours of processortime . . . free!

Here's my problem: Our BASIC sys-tems (we have 2) are gelling so popularit's getting very difficult to get keyboardlime or even overnight lime. Is it pos-sible to use the HP 9830 as a terminalfor an 8080 system (or whatever)? Itseems to me lhat there would be a goodmarket for a 9830/8080 interface. TheHP IO goodies - cassette, keyboard,display and printer - could be used toload and unload an 8080 job, and whilethe 8080 is running, the HP could goabout its normal duties. We could doubleour throughput for peril,ips an additional20% cost.

One could even envision several sub-sidiary 8080 processors! Further, withthe output data fed hack to the HP, ourHP peripherals could be used (plotter,paper tape, mass memory ... I told youI was spoiled). Any suggestions?

Ted Tharp

POB 133

Norfolk CT 06058

The only way which < ould probablyhave any semblance of being practicalwould be communication over a serialcommunications line hardwired betweenthe two processors. The combination ofthese particular machines is probably nottoo common, and I would hardly expectHP to engineer an Allair bus interface(or vice versa). It's probably cheaper tobuy another 9830.

ON HUNTING THE FORTRANPTERODACTYL

Reading Mr Lashley's letter inFebruary 1977 BYTE was, for me, amatter of seeing the same old wives'tale one time too many and, therefore,I feel compelled to voice my opinion onthe mailer. To paraphrase, I can onlyconclude that Mr Lashley has beentheorizing too long (and practicing toolittle).

To call FORTRAN a pterodactylis perhaps correct but very misleading ifit is not accompanied with an explana-tion that FORTRAN is archaic in thesense that the English language is archaic.English is so messed up that it is imprac-tical to program a computer to under-

112

stand it directly, yel we hear very fewvoices advocating a wholesale switchto Esperanto. Like English, FORTRANhas become a de facto standard andunless we wish to make like the denizensof Brave New World, severing all lieswith the past, we will have to live with it.

In his letter, Mr Lashley also slatesthat the language one learns first influ-ences later programming el forts. Asbefore, I must insist on setting this state-ment in the proper context. I here is atendency on the part of poorly trainedprogrammers to mistake the languagefor the machine. This is a deficiency onthe part of the person and has nothinglo do with languages, pterodactyl orotherwise. A properly educated pro-grammer has a good understanding ofwhat transpires in a mainframe. Toachieve this understanding il is nolnecessary lo delve into electronics orBoolean algebra, but it is essential tocomprehend the concept of "a copyof the contents of box A is placed inbox B" to such a degree that one cansee how these simple functions can per-form complex tasks.

One should begin programming inFLOWCHART, the universal symboliclanguage, and allow this language tobecome the one that influences laterthoughts and actions. When, after suf-ficient instruction and practice, it be-comes natural to describe a clearlyunderstood sequence ol machine actionswith a symbolic representation ofsquares, diamonds and arrows, the highlevel language used to effect the transla-tion becomes dependent on factorsother than the programmer's personalhangups. For example, if the programat hand involves extensive matrix opera-tions, BASIC or APL can save con-siderable coding time; if financial opera-tions are involved, COBOL might be anatural choice; if universality is impor-tant, FORTRAN might be the only wayto go. In any case, the programmershould never lose sight of the fact that ahigh level language is little more than avehicle to get from concept to finalproduct.

At present, supporting a full blownhigh level language compiler is quite anachievement for a personal computer;supporting several is out of the question.For this reason it is important to makethe best possible selection and to selectsome obscure educational vernacularsuch as PASCAL because it is estheticallymore pleasing, and would leave personalcomputing where il is right now: a lotof hardware with very little software.

Jack Crone, Systems Analyst

USC School of Medicine

Hoffman Research Ctr, Rm 805

2025 Zonal Av

Los Angeles CA 90033

BIT SLICE 360/370 MACHINES?

Is there anyone out in personal com-puting manufacturing land thinking ofhooking up some bit slices and read onlymemory to make a machine which can

run IBM 360/370 instructions? For alow cosl (SI 000) ii may not be possibleto implement all the features of thearchitecture (virtual systems, cache mem-ory, error checking and correction, etc),but then the hobbyist probably wouldnot need to pay for multiple virtual sys-tems, anyway. It should be possible tobuild a cheap 360 emulator to mimic aModel 30 or 40. Have you heard of anyplans to do so?

Tom Koon, industrial engineering

Texasgulf Canada Ltd

POB 2002

Timmins, Ontario CANADA

No; but one acquaintance men-tioned the idea of a generalized 36 bitprocessor board with an expandablelarge system's instruction set, startingat about $2000 or so.

SOME THOUGHTS ON CLUBS

On page 126 of the August BYTE youraised some very thought provoking issuesregarding the functions of regional and localcomputer clubs. You also have asked aquestion which I think all computer buffsshould give some consideration to: What arethe pros and cons of a national homecomputing association and how could itrelate to those of smaller groups? I discussedyour editorial at a meeting of local computerbuffs, Advanced Technology Research Asso-ciates (ATRA), and here are some of theideas we brainstormed:

A. Central Issues, Problems, Trends that allcomputer clubs will have to handle.

1. If small system users are to realize thelull benefits of the powerful yet inex-pensive hardware that manufacturersare promising us, then the number ofsystems and users must increase byhundreds of thousands annually. Thesame applies to software when thecosts of commercially produced pro-grams can be distributed over, say, amillion systems a year.

2. This growth will take place al a limewhen rapid technological change willbe affecting not only computers, binalso other devices that computers canbe linked to: audiovideo systems, Elec-tronic Funds Transfer systems andmany others.

3. The uninformed people who will oftennot understand the freedom potentialsof home systems will often regardcomputers and many computer appli-cations with a high degree of paranoia(witness the controversies in automa-tion and EFT). And even data process-ing professionals with their ownsystems must be able to cope withinvasions of their privacy, softwaretheft, and other new issues raised byadvancing technologies. Thus, bothusers and nonusers can benefit if wecan create environments where theycan dialogue on the problems andopportunities computers present tothem personally.

I. hems No. I through No. 3 seem toargue lor fast growing organizationswhere people can exchange both facts

and opinions rapidly and in greatdetail. Since the volume of newcomerscould greatly outnumber experiencedcomputer buffs, new methods of com-munication, organization, and decisionmaking would need to evolve. The keyword for rapid learning and socializa-tion is dialogue.

B. Functions of Local and Regional Com-puter Groups

1. Obviously, many smaller computerclubs will have the effect ol dispersingrapid growth more evenly. This in turnwill allow traditionally organizedgroups to survive longer. It will alsogive the innovators time to try outnew techniques for opening communi-cations, such as the Homebrew Com-puter Club's "mapping session" whichwas reported in the August BYTEeditorial. Eventually each group willprobably develop its own uniqueapproaches to coping with growth.

2. Club activities will give local groupsvaluable experience not only in com-puters hut also in working together.Larger clubs should probably strive fora greater number and variety of proj-ects so as to keep the work groupssmall. More projects also give moreopportunities for people with differentinterests to find something thatappeals to them.

3. Finally, the larger local groups willprobably start experimenting withinnovative methods of decision makingand group organization. These mayinclude:

a. Revised computer assisted Roberts(Robots?) rules ol order for run-ning committee meetings with verylarge committees.

b. Delphic probe issue definition tech-niques, handled via a conferencenetwork.

c. Matrix analysis or decision treecharts regularly updated by com-puterized text editing programs.These can be used to help under-stand complex and constantlychanging interrelated problems.

d. Sunset rules lor the table of organi-zation and bylaws. After a givennumber of years the group's charter(or related portions of it) wouldhave to be examined and approvedby the group's vole. Otherwise thesunset clause would dissolve itscorporate standing.

I believe that the systems analystsamong local computer buffs will findmany other methods of helping theirorganizations.

C. Functions of a National Home Computerand Small System Users Association

1. Clearinghouse loi exchanging informa-tion on innovative communications,organization and decision making tech-niques developed in local groups.Super 8mm films, role playing, andtransplanted hardware lor demonstra-tions could be used to disperse thesetechniques among other groups.

2. Promote new technologies which showgreat potential for integrating intohome computer systems. The laservideo disk Martin Buchanan discussed

113

Microcomputer

QudydOAl

does much more

with the Z-60.

' ;'"'

I ©uau

'^■f . as. ''te'- 'Mn BMk . 1 ■'■■»-

■3* '

This dynamite new microcomputer -system in a kit moves data lite nothingelse on the market. Run it alone orplug ir into an 5100 bus Altair/IMSAI.For solo performance, all you need is"an unregulated power supply and anI/O device. Plugged in, Quay 80AI is aCPU/ROM, SIO, and RAM'board-runany 5100 compatible device. BUTMORE THAN THAT. Quay 80AI's Z-80CPU opens challenging new areas ofpersonal computing.

Features

"O S100 bus compatible. Plugs in one slot ofyour Affair or IM5AJ.

'□ Z-80 w/2.5 MHz clock.

P 1 K static RAM.

□ 512 byte (ROM) monitor. Comes uprunning. Inspect alter, dump, and loadmemory; set breakpoint; jump to userprogram. Handles serial I/O or keyboardinput, including setting baud rare.

D 4 UVEPROM (2708) sockets.

Q Serial I/O RS-232 and 20 ma Interface.

□ Parallel keyboard input. Accepts stan-dard ASCII keyboard.

□ UVEPROM programmer. Program 2708type UVEPROMs.

D 2 phase clock and sync. Run 5100 com-patible peripherals.

D 158 instructions. All 78 3080 instrucrionsplus 80 new powerful instructions.

D On board voltage regulators.

Quay 80AI in 0 kit is $450; factory as-sembled, $600. Send for completedetails. Or for fast action call 201 ^681-8700.

Masterchorge and OonkAmerlcard accepted. COD with1 /0 deposit. NJ. residents add 5% sales tax. Wee doesnot Include shipping and handling.

Dealer inquiries invited.

P.O. Box 366, Freehold, N.J. 07728Phone: 201-681-8700

ThE COMPUTER RQQM

SMALL COMPUTER SYSTEMS • SOFTWARE • AMATEUR RADIO EQUIPMENT

1455-ASo. 1100E. Salt Lake City, Utah 84105 Phone:801-466-7911

"WE TAKE THEm\m OUT OF THE MICRQ

One Of The Nations LargestFull-Service Computer Stores.

Over 1600 Square Feet Of SalesAnd Service Facilities.

WHEN YOU WRITE FOR OUR CATALOG AND ENCLOSE $1 TOHELP DEFRAY THE COST OF HANDLING AND MAILING,HERE'S WHAT YOU GET:

1. A CERTIFICATE GOOD FOR $2 ON YOUR NEXTPURCHASE

2. the COMPUTER RQQM easy to understand

CATALOG COVERING

I MSA I

THE DIGITAL GROUP

POLYMORPHIC SYSTEMS

SOUTHWEST TECHNICAL PRODUCTS CORPORATION

TECHNICAL DESIGN LABS

ETC.

3. the COMPUTER RQDM -easy guide- to help you

PICK THE RIGHT SYSTEM, PERIPHERALS, COMPONENTS,AND SOFTWARE FOR

THE BEGINNERTHE ADVANCEDTHE EXPERTTHE SMALL BUSINESS

4. A CURRENT LISTING OF PRESENTLY AVAILABLE

SOFTWARE

PUBLICATIONS

PERIPHERALS

5. INFORMATION ON REPAIR SERVICE, LOW COSTCUSTOM PROGRAMMING AND OTHER SPECIAL SERVICES.

AT THE COMPUTER RQQM YOUR WRITTEN QUESTIONSARE HAPPILY RECEIVED AND PROMPTLY ANSWERED

WE ALSO STOCK A COMPLETELINE OF AMATEUR RADIO EQUIPMENT

BANKAMERICARD

.MASTERCHARGE114

in the August BYTE is an excellentexample of a technology thai might liea boon for hobbyists and non-computer users alike //"manufacturersbecome aware of its long range poten-tial. Unfortunately, some observersthink RCA's capacitance disk may beeasier to produce. They also think thevideo playback unit would be lessexpensive due to its use of more "offthe shelf" technology. And, of course,the Japanese are always getting betterwith video tape. Now, if a potentnational group were to gel into thispicture by (a) giving technical adviceto its favorite publication? and (b)publicizing the vast benefits the gen-eral public could reap, we could prob-ably tip the balance. Right now peopleare thinking mainly of recordedmovies - and most potential videodisk manufacturers are busily trying tonail down distribution rights. But withsome good publicity for laser diskslinked lo quadraphonic modular com-puter systems, people may not so!liefor less. Let's go for the moon!

3. Establish standards for new com-mon hardware-software interfaces andratify them by voting. Also, is ASCIIalways going to be the standard com-munication code? ASCII has 7 bits butalready UARTS and USARTS cantransmit 8 bit code. Eventually tech-nological changes will have an impacton the interfaces of millions of com-puter users. While I'm sure BYTE willalways be there to help, a nationalorganization with elected representa-tives will be needed lo assure fairnessto all.

4. Apply political pressure, if necessary,to unreasonable restrictive practices bythe phone company. Home computertechnology is largely an outgrowthfrom telecommunications. Eventuallytimesharing and network techniqueswill combine to place tremendouscomputing power in the hands of theaverage person. Bui already someeducational computing users are com-plaining about the higher costs of MaBell's new SMRTS charge syslem inCalifornia. This may be just thebeginning.

5. Speaking of telecommunications, aNational Home Computer UsersWATTS line for relaying digilal mes-sages from one computer club loanother would be a fantastic service. Itwould also make coordinating activi-ties much easier. When you exceed theline's 4800 baud capacity you couldstart negotiating with commercialcarriers.

D. Pulling It All Together: National Con-ferences and So On

A national conference organized from thegrass roots seems a good move. But if such aconference lakes place the group sponsoringil will have to be one with a great deal oforganizing experience. This raises a lol ofquestions: Will il be a continuing electedbody financed by a membership fee? Will ilrotate from one computer club lo anotherdepending on who wins the bid?

I think thai a volunteer group can prob-ably do some fantastically imaginative things

Youcmuy..

oo

1300

GUMBALL5

3 6K055

of \m

CALENDAR

[WiTrt ?RU

FELT pen TOCrtANSC DAWS]

2\ MUR5 OF

IWLANX OfA5ACUS£5C ABAC)? J

ONE

HALF-YEAR'S

MEMBERSHIP

IN THE IEEE

COMPUTER

SOCIETY

INCLUDING ANAu7bMATiC

TO COMPUTERWAGAZi/Vfi

20,000

DDa 7*0 Tht Fm jMty^wno^ieN up,

WfXf WROWiNG IN A /^ff COFY'oF

M/CfiO/WOC£S£Ofi'S&MiCROCOMrur£X3...

A NEAT LiTTLE COLLECTION OF KEPFiHTS FKOtA COMPUTER.

Organized and introduced by our technical editor, this volume carries a balanced selection ofeverything we've published in COMPUTER about micros over the past two years.

Circle reader service no. 67.Find out why membership in the IEEE Computer Society is one of the best investments you'll ever make.

* Offer expires July 1, 1977.

IEEE COMPUTER SOCIETY

5855 Naples Plaza, Long Beach, CA 90803

COMPLETE

FLOPPY DISK SYSTEM

FOR YOUR ALTAIR/IMSAI

$699

That's right, complete.

The NorthStarMICRO-DISK SYSTEM™ uses the Shugartminifloppy™ disk drive. The controller is an S-100 com-patible PC board with on-board PROM for bootstrap load. Itcan control up to three drives, either with or withoutinterrupts. No DMA is required.

No system is complete without software: we provide thePROM bootstrap, a file-oriented disk operating system (2kbytes), and our powerful extended BASIC with sequentialand random disk file accessing (10k bytes).

Each 5" diameter diskette has 90k data byte capacity.BASIC loads in less than 2 seconds. The drive itself can bemounted inside your computer, and use your existing powersupply (.9 amp at 5V and 1.6 amp at 12V max). Or, if youprefer, we offer a power supply ($39) and enclosure ($39).

Sound unbelievable? See the North Star MICRO-DISKSYSTEM at your local computer store. For a high-performanceBASIC computing system, all you need is an 8080 or Z80computer, 16k of memory, a terminal, and the North StarMICRO-DISK SYSTEM. For additional performance, obtainup to a factor of ten increase in BASIC execution speed byalso ordering the North Star hardware Floating Point Board(FPB-A). Use of the FPB-A also saves about 1k of memory byeliminating software arithmetic routines.

Included: North Star controller kit (highest quality PCboard and components, sockets for all IC's, and power regula-tion for one drive), SA-400 drive (assembled and tested),cabling and connectors, 2 diskettes (one containing file DOSand BASIC), complete hardware and software documentation,and U.S. shipping.

MICRO-DISK SYSTEM ... $699 To place order, send

(ASSEMBLED) $799 check, money order or

ADDITIONAL DRIVES. . . $425 ea. BA °r MC card # with exp.

T date and signature. Uncer-

DISKETTES $4.50 ea. tified checks require 6

FPB-A $359 weeks processing. Calif.

(ASSEMBLED) $499 residents add sales tax.

NORTH STAR COMPUTERS, INC.2465 Fourth StreetBerkeley, CA 94710

with litis kind of conference. If would be agreat way of showing off an intraconferencecommunications network or gaming system,For example. And, if the group organizingthe event took a few hours to learn dictationtechniques, they would contract with a wordprocessing service organization to type alltheir correspondence. All they would haveto do is pick up a telephone, dial a certainnumber and dictate a memo, letter orteletype to an automatic recorder. Trainedstenographers would then type the messagein the desired medium.

At this stage the possibilities are quitenumerous; but I hope that our group hasbeen able to help give a little perspective tothe topic. Speaking for ATRA, I wish tothank you very much for launching thisdiscussion within the pages of BYTE. You'redoing a great service there. Keep up thework.

Frank Stodolka

POB 456

Minneapolis MN 55440

Attending members: Terry Belcher,

David Cargo, John Stanley, Richard Tatge

BYTE'S BARQUE, IDENTIFIED

I would like to comment on the pictureon page 107 of the October issue of BYTE. Iam 99.44% certain the ship is the bark(barque) USCGC EAGLE. I say this since Iam a 1967 graduate of the USCG Academy,and had four summer cruises aboard EAGLEas a cadet. If you get any mote responses tothis picture, it might be interesting to knowhow many other USCG Academy graduatesare BYTE readers.

Clifford ) Appel

6047 Woodminster Cir

Apt #12

Orangevalc CA 95662 ■

BYTE's Bits

Quick and Simple Pot Input Method:

Robert Patton, WS0I, of lesterCenter, Austin TX 78784, notes thepublication of a very simple idea forgetting input from a potentiometer witha microprocessor. The idea appeared inthe March 4 1976 issue of Electronicsmagazine, page 123, and can be sum-marized very simply: Make the timingresistance of an NE555 type timer cir-cuit be a potentiometer, and hook upthe circuit as a triggered oneshot. Thentrigger the pulse with a strobe from thecomputer and measure the length of thepulse with a programmed timing loop.The program watches the output of thetimer through a single bit input port andterminates the loop when the end of thepulse is reached. The count obtained inthe timing loop will be a function oflength of the pulse as set by the variableresistance. ■

116

New ASCII Standards

Twenty five additional controls are beingstandardized for use with the AmericanStandard Code for Information Interchange(ASCI I) in 7 bit and 8 bit environments. Thedraft proposed American National Standardentitled Additional Controls for Use withASCII is out for public comment as BSRX3.64.

The primary thrust of the standard is toencode the control functions needed by thecurrent technology of two-dimensional char-acter imaging input output devices, such ascathode ray tube terminals. The ANSI X3Technical Subcommittee X3L2, Coding andCharacter Sets, has been working on thestandard since 1969.

It is a comprehensive standard whichshould standardize information interchangefor this decade in a manner similar to thatprovided by ASCII in the last decade. Thestandard uses a multiple character structuresimilar to an Escape Sequence to obtain 78distinct functions. Furthermore, it uses auniform method for representing bothnumeric and selective parameters to indicatedimensional quantities and to obtain 88more subfunctions. Finally, 23 modes alterthe interpretation of some of the functions.

The following diverse information inter-change applications are addressed:

1. Interactive terminals of the cathoderay tube type

2. Interactive terminals of the printertype

3. Line printers

4. Microfilm printers

5. Software usage

6. Form filling

7. Composition imaging eg: typeset-ting

8. Word processing

9. Input output devices with auxiliarydevices

10. Buffered and nonbuffered devices.

The types of controls include editingfunctions, formatting, and the specificationand control of input areas, as well as certainstatus setting and interrogation functions,mode selection and typesetting compositionfunctions. The standard does not containany network or data transmission controls.

The standard is open-ended so that morecontrols can be included in future revisions.Furthermore, a conforming implementor isprovided with a means of implementingsome so-called private, nonstandard func-tions as well. As with ASCII, it is notexpected that implementors will implementall of the functions in the standard.

A compatible subset of this dpANS wasapproved in June 1976 by the EuropeanComputer Manufacturers Association(ECMA). It is entitled ECMA-48 AdditionalControls for Character-imaging I/O Devices.

Copies of the 100 page dpANS BSRX3.64 are available from R M Brown,Director of Standards, CBEMA, 1828 LSt NW, Washington DC 20036. Pleaseenclose $3 for each copy. Comments areencouraged and should be returned toCBEMA at the above address before May 281977."

LET YOUR COMPUTER XPRES ITSELF!

Your computer can controllights, burglar alarms,Hi-Fi's, PHASORS;practically anything ifproperly interfaced.

XPRES is a complete interface system. ONE EIGHT BIT PORTOR ONE SERIAL PORT CONTROLS 128 SEPARATE DEVICES.Connect to IMSAI, Altair, or SWTPC; any processor with aneight bit or serial port. Use ISB-01 for serial connection toprocessor.

IMB-01 system mother board, holds five interface boards,complete with connectors. KIT $28.00

IFB-01 interface board, controls two 115 VAC 300 watt cir-cuits. Optically isolated. KIT $38.00

IFB-02 interface board, controls four 3 amp 115 AC/DCcircuits with on-board relays. KIT $58.00

IFB-03 prototype board, build your own interface. Boardincludes XPRES bus decoders. KIT $15.00

IFB-04 interface board, controls 4 small signal AC/DC cir-cuits with reed relays. KIT $36.00

IFB-05 drives 4 IRB-01 remotes (below) with low voltagelines. KIT $29.00

IRB-01 remote 115 VAC 300 watt interface. Build into yourown equip. 2" X 2V2". KIT $17.00

ISB-01 drive XPRES system with a single TTY line, 20 ma.,RS232, or TTL. Plugs into IMB-01. KIT $48.00

Wash, residents add 5.4% tax.

CRC Enqinee

P.O. Box 6263Bellevue, Wa. 98007(206) 885-7038

BankAmericard

117

NOW!!

Z-80 Power for the S-lOObus without getting rid o£

your CPU card

159.95

assembled

\

, *Y»*+-*'«4s4*M<-s*iS» 180-80;

UU 1 £\.\jl\ 1 Lju a leader in low cost, low power ram boards has just announced it's Zj oU — oUpiggy back card. This plug — in board enables you to use your existing 1MSA1, ALT AIR CPU cardand upgrade your system to a Z — 80.

The card design is such that all you do is pull out your 8080 and 8212 chips, plug in the Boardto the 8080 socket itself and the ribbon cable to the 8212.

A system monitor, on paper tape, is included with the board as well as a 280 Manual and Theoryof Operation Manual.

Dutronics will also supply all additional software at no cost, when it becomes availableThe price is $159.95 (assembled) only. OFF THE SHELF.

for more information call or write to:

BYTE OF PHILADELPHIA1345 W. Lancaster Ave.Bryn Mawr, Perm. 19010(215) 525-7712

BYTE OF WESTMINSTER14300 Beach Blvd.Westminster, Ca. 92683(714)894-9131

R.H.S. MARKETING

2233 El Camino Real

Palo Alto, California 94306

BYTE OF PALO ALTO2227 EI CaminoPalo Alto, Ca. 94306(415)327-8080

BYTE OF SANTA CLARA3400 El Camino RealSanta Clara, Ca. 95051(408) 249-4221

(415)321-6639

DEALER INQUIRES INVITED

v

HOBOKEN COMPUTER WORKS20 Hudson PlaceHoboken, N.J. 07030(201 420-1644

BofA & MASTERCHARGE ACCEPTED

16384 BYTES for $485.00

assembled (with sockets) : tested - burned in - guaranteed

.***»

A new high in SlOO bus memory cost effectiveness. Fully assembled(with sockets J, tested, burned—in and guaranteed. 4Kxl dynamicmemory chips (the same ones used by the ton in IBM compatible memory systems) combined with self contained controllogic, yield a memory system with:

• Low power consumption, total board 5 watts.

• Transparent refresh, which means thememory looks static to the outside world.

• No waiting. In fact, xrdy is not even con-nected to the memory.

• Full DMA capability

• Reliable, low level clock and control-signals.

Dynabyte

LJyTlCiuy 16 brings to the S-JOO Bus a state of the art, Indus trial quality memory system.16K on a single board for $485.00, Guaranteed for 1 year.

BYTE OF PASADENA496 So. Laic A ve.Pasadena, Ca. 91109(213) 684-3311

BYTE OF SANTA CLARA3400 LI Camino RealSanta Clara. Ca. 95051(108)219-1221

BYTE OF WALNUT CREEK

2989 N. Main St.

Walnut Creek. Ca. 94596

(415) 933-6252

BYTE OF SAN MATEO

1200 II. Hillsdale Blvd.San Mate,,. Ca. 91403(415) 311-4200

BYTE OF PALO ALTO

2227 1:1 (laminaPalo Alto, Ca. 91300(115)327-8080

for more information call or write to:

R.H.S. MARKETING

2233 El Camino Real

Palo Alto, California 94306

(415)321-6639

DEALER INQUIRES INVITED

BofA & MASTERCHARGE ACCEPTED

Classified Ms

FOR SALE: Two Digital Group 8 K memoryboards, $180 each. Each board has 7 K 21 L02-1and 1 K 2102-1. Presently running on a Z-80system. Send SASE and your check will bereturned if boards are already sold. Tom Rin-gate, 281 1 W 112th St, Bloomington MN 55431.(612) 881-8743.

FOR SALE: Complete wiring diagrams packet forTeletype Model 33ASR TWX with 101C Dataset,S5.50 each postpaid. Model 15 gear sets, 60, 67, 75wpm. Gear sets for Model 28, 35 equipment.Model 28 printers, ASR, KSR, RO, sprocket feed,friction feed. Model 35 8 level ASCII TDs, reper-ferators, page printers. Model 35 type boxes, $40each. Model 32/33 parts and accessories. Model32/33 copyholders, S16 each. Write for full listing.Send SASE to Lawrence R Pfleger, 532 W WilsonSt, #1, Madison Wl 53703.

FOR SALE: HP-55, with recharger, battery pack,safety travel case, soft carrying case, owner'shandbook, quick reference guide, programmingworksheets and name labels, plus security cradle,reserve power pack (less battery) and extra re-charger. Please quote offer; if no reply, outfit hasbeen sold. Write: Frank Scavo, 1811 Court St,Syracuse NY 13208.

MICROAPPLICATIONS: I would like to cor-respond with anyone interested in microap-plications in civil and structural engineering. DavidLavers, Suite 224, 805 5th St SW, Calgary, AlbertaCANADA T2P 1W3.

WANTED: Wish to buy first ten issues of BYTE.Evan H Foreman, POB F, Mobile AL 36601.

FOR SALE: Brand new Honeywell DSU-160 (IBM2311 equivalent) 7.5 MB with full documentation,including SPC-16/40 controller diagrams, $1600.Ampex TM-7, 9 track tape transport, $450 withdocumentation. Roytron 75 cps paper tape punch,$350. TRW 300 cps paper tape reader, $200.Buster Killion, 2773 Winrock Av, Altadena CA91001. (213) 798-2977.

FOR SALE: Assembled IMS UCRI cassette inter-face board, can also be used as 4 bit D to A and

1 bit A to D, $35. Assembled SWTPC TVT CT-Lboard, $12. Tarbell cassette tapes of MINOL 2.2 (a

2 K Tiny BASIC for the 8080, IO patches pro-vided), $4. Erik Mueller, 36 Homestead Ln, Roose-velt NJ 08555. (609) 448-2605.

FOR SALE: Rockwell PPS-8 system, includingCPU, IO, 4 K dynamic programmable memorywith refresh and control, 256 byte scratch pad, businterfaces, clock, and sockets. Over $400 list. Willsell for S200. Ten Signetics 300Z slices, $35.K Tyree, 2182 Coastland Av, San Jose CA 95125.(408) 265-2575 or 744-1290.

WANTED: Microdata Model Micro-400 or Micro-400/10 processor, any condition. Saul Meyer, 1 734Green Valley Rd, Havertown PA 19083.

Readers who have equipment, software or otheritems to buy, sell or swap should send in a clearlytyped notice to that effect. To be considered forpublication, an advertisement should be clearlynoncommercial, typed double spaced on plainwhite paper, and include complete name andaddress information. These notices are free ofcharge and will be printed one time only on a spaceavailable basis. Insertions should be limited to 100words or less. Notices can be accepted fromindividuals or bona fide computer users clubs only.We can engage in no correspondence on these andyour confirmation of placement is appearance inan issue of B YTE.

Please note that it may take three or fourmonths for an ad to appear in the magazine.*

FOR SALE: Innovex Model 210-M (serial #1823)floppy disk drive and one floppy disk withcomplete manual and schematics; Never been used.Same type of drive used in February 1977 BYTEarticle on interfacing a disk to an 8080 system. Willship. $500 or best offer. Mark Becker, 32 OxfordRd, Newton MA 02159. (617} 332-8686 after4 PM.

FOR SALE: Processor Tech 4 K static program-mable memory assembled, works perfectly, meetsall specs, with all documentation, $150. Freeunused paper tape of 5 K BASIC, documentationincluded with 4 K board. Barry Gerber, 720 MorseAv, Placentia CA 92670.

FOR SALE: 1103 1 K x 1 RAM by Intel with inhouse numbers. Each one individually tested withseveral patterns and guaranteed to meet 1103specs. I must sacrifice 280 of these and must sell inone lot. Metal tubes are included to protect thechips during shipping. Think of what you can dowith 35 K of memory! The order could also besplit with a friend. You cannot beat the low priceof $.80 each. I will pay shipping costs. Act quicklyand send a cashiers check or money order only toStephen Marcus, 1284 W Camino Desierto, TucsonAZ 85704.

FOR SALE: Wire wrap boards. These brand new 6by 5Ya inch boards can hold 60 14 pin ICs and canbe easily modified to hold 16 to 40 pin ICs. Thesehigh density boards also have two uncommitedrows to hold discrete parts. Manufactured byAugat and Cannon, they have gold plated pins andare still in their original cartons. Have several ofthese at $15 each. Call Bob Runge at (305)723-6303 or write RR 2 POB 540, Melbourne FL32901.

FOR SALE: Altair 8800 with 1 K memory. As-sembled by experienced builder and in goodcondition. Will pay postage and handling. Firstmoney order for $425 takes it. Dave Norris, POB2672, USAFA CO 80841.

WANTED: I need BYTE !ssues 3, 8 and 9 tocomplete my collection. Send condition of sale toCarl Shirey, 5038 Central Av, Portage IN 46368.

FOR SALE: Seals 4K RAM board. New, as-sembled and run in for a 72 hour check. Features21L02B-1 and 8T97B buffers, complete withschematic. I'll pay US postage. Send certifiedcheck or money order for $155 to J M Church,4307 Mar-Moor Dr, Lansing Ml 48917.

FOR SALE OR TRADE: IBM 2311 disk drive, justoff IBM maintenance, 7.5 MB of storage. Best offergets it. Bill Barrow, 30 Albemarle Av, RichmondVA 23226. (804) 270-2382.

TRADE: Will trade computer programs in BASIC.I have many programs available in HP 2000 C/Fand other versions. Write Bill Seurer, 4249 Brown-dale Av, St Louis Park MN 55416.

FOR SALE: Compucorp Beta 326 microcomputer,complete with software and TTY interface, $995.Assembled SWTPC 1024 terminal with serial inter-face, power supply, computer cursor control, RFmodulator and case, $275. Tl Sr-52, $125. Writefor information to Tony Copplin, POB 3440, NLas Vegas NV 89030.

FOR SALE: MITS parallel IO board (88-PIO) forthe Altair 8800, $80 assembled. Two MITS 4 Kdynamic memory boards (88-4MCD) with edgeconnectors, $200 each, assembled. David Richards,6655 Hill St, El Cerrito CA 94530. (415)529-0759, evenings.

FOR SALE: Teletypes; CDC 2816 typewriter,paper tape punch and reader; CDC 9300 lineprinter; Mohawk Data Sciences 6021 optical cardreader (Soroban ERC-1); Honeywell 404-3 Serial-*rBPS14 9 track, 3/4 inch tape drive; Milgo tapebuffer 1807-1A Smart interface for 24 bit SDS910; TRW graphics display system. Call Bill Palya,120 N Weston, Rensselaer IN. (219) 866-7111.

FOR SALE: Altair 680b, assembled and runninggreat. Best offer over S300. Alan Dahlbom,16 Forest St, Cambridge MA. (617) 492-0676,evenings.

FOR SALE: DECwriter LA36, one year old,$1200.' Brand new PDP-11/03, $1995; with addi-tional 4K memory, $625; total 8 K RS 232Cinterface, $235. List $2855, less 25% net, $2140.Also Modem Omnitek 701B, minimum six for$1000, 160 additional units. Walter D'Ull, 2239Grand Concourse, New York NY 10453. (212)933-0300.

FOR SALE: Floppy disks, $4 each. Computer tape800 bpi, Ampex, Memorex, IBM, $4 a reel.Guaranteed. Trimble, 5835 Herma, San Jose CA95123. (408) 224-0606.

FOR SALE: Altair 8800a CPU board, factoryassembled and tested, never used, $250. JonathanRotenberg, 17 Chestnut St, Boston MA 02108.(617) 227-1399.

FOR SALE: One Altair 8800 computer, new,assembled from kit, but not tested, $439. Also,two Altair 88-4 MCD 4 K dynamic programmablememory boards, $199 each. Contact Bob Stodola,1910 Beachwood Av, St Paul MN 55116.(612) 698-2731.

WANTED: I need six or eight 2708 PROMs(500 ns) at a reasonable price. Other pin compatibletypes are fine if they can be programmed in anIntel machine. Write: Theron Wierenga, 80 WSouthern, Muskegon Ml 49441.

FOR SALE: Issues 1 to 3 and 1 to 5 of BYTE,excellent condition, no clipped coupons. Will sellto highest bidder. Specify issues 1 to 3 or 1 to 5.K Matthews, -117 20041-55A Av, Langley BC,CANADA V3A 5V4.

WANTED: Issue =9 (May 1975) of BYTE maga-zine. G W Hippisley, 112 Kennedy Ln, N SyracuseNY 13212. (315) 458-0940.

TRADE: I have extra copies of BYTE issues 1through 16 and wish to trade for INTERFACEDecember 1975 through June 1976. I will alsobuy these outright. Contact: Robert S Martin,143 Pyne Hall, Princeton University, PrincetonNJ 08540.

FOR SALE: SWTPC 6800 system, 16 K program-mable memory, additional serial IO board, all ICsin new Tl and Ancrona sockets. All current SWTPCsoftware included, $725. AC-30 and PanasonicAC/DC cassette tape unit. All ICs in new Ancronasockets, $120. All equipment was assembled withcare and is in excellent condition. Louis Schubert,3807 Greenhill Dr, Chamblee GA 30341. (404)457-6842 or (404) 881-8800 ext 383.

FOR SALE: Viatron microprocessor system with73 key keyboard, two cassette drives and inter-faces, 9 inch video monitor and interface, powersupply, cabinet and manuals, $600. ContactB Pelkey, 74 Applegate, Bennington VT 05201.(802) 447-0259.

FOR SALE: Friden Model TM20K714 keyboard-printer with TM20K15 controller and schematics.$300, you pay shipping. Also copies of schematicsfor above controller available for $6 to covercopying and first class shipping. Tim Ahrens, 2200Sorret Tree Ct, Austin TX 78744.

FOR SALE: IMSAI 8080, 8 K IMSAI memory, 22slot mother board, IMSAI audio cassette board.Processor Tech 3P+S interface, Oliver Audio En-gineering OP-80A paper tape reader, plus muchmiscellaneous software, plugs, sockets, etc. All inlike new condition, $899. Ken Schweim, 1709Mary Ln, N Mankato MN 56001. (507) 388-5734.

WANTED: Contact with persons who have aserious personal interest in using a microcomputerfor stock and commodity market investment pur-poses. If covariance is more than just another wordto you, send a brief note of your desires, qualifica-tions and market experience/involvement toJ Williams, 2415 Ansdel Ct, Reston VA 22091.An association is being formed.

FOR SALE: Six used Augat 8170-RG1 13 slotwire wrap rack assemblies, $311 list, sell for $75each; 16 used 8136 R series panels with 60 14 pinsockets, $15 each. Gary Manigian, POB 181, ParkRidge NJ 07656.

120

What's

New?

Monitoring What Goes On in Your Computer

One of the most common desires ofthe personal computer user is theachievement of high quality output atminimum cost. Going through the RFconversion route from a video displaygenerator to a TV set works, but is notnecessarily the best way to achieve ahigh resolution display.

One solution to the problem is a kitof parts and information from a firmcalled Pickles and Trout (after its own-ers) which has just introduced this TVmodification kit. The Pickles and TroutTVM-04 kit is available for $20 and willallow the builder to modify any inexpen-sive commercial television set which usesthe Hitachi SX chassis, turning it into amonitor which accepts standard EIAformat video signals with peak to peakamplitude levels adjustable by selectionof one resistor. The Hitachi SX chassis is

TV MOD KIT

ftBCEffCMMItlOWttllMttY? I1?34567B9 ''lltj-'d

$20

available in several different models oftelevisions including P-03, P-04, P-05,P-08, P-53 and P-63. The example shownin the photograph is a Hitachi P-05portable which sells in typical retail anddiscount houses for $79.95.

As seen in the photograph, the resultis a high resolution product, which willaccept video generator outputs with upto 90 characters per line, more thanadequate for any of the currently mar-keted character display modules.

How To Use It . . .

Since this product must be installedinside the commercial TV, questions ofwarranty and finger pointing apply. Thefirm has answers to such questions in the

<§•

-> o /\ :r> ^*■* ^ n n ^

following recommendation: Purchase theTV set first, use it intensively for about amonth or two of concentrated viewing(if you can stand watching TV for thatlong) to make sure the electronics haspassed your incoming inspection. Thenthere is little likelihood of a manufac-turing problem with the TV set, so youcan safely go ahead with the changes,confident that if it doesn't work youprobably made your own installationerror.

Pickles and Trout are located at POB2276, GoletaCA 93018."

An 8080 with FORTRAN Options

Realistic Controls Corporation hasannounced this new "Z//100 Series" of

HOBBY-WRAPModel BW-630

WIRE WRAPPING TOOL

For AWG 30, .025" (0,63mm) sq. post,"MODIFIED" wrap, positive indexing,anti-overwrapping device

Battery

wrapping

(batteriesnot included)

OINLY ^^ ^» not included)

COMPLETE WITH BITAND SLEEVE

OK MACHINE & TOOL CORPORATION

3455 Conner St., Bronx, NY.10475 / (212) 994-6600 / Telex 125091

tabletop personal FORTRAN machines.According to the company, the threemodels in the Z//I00 series are portable8080 based microcomputer systemswhich are available with a file manage-ment system and an optional FORTRANIV compiler.

All three models are built around an8080 processor. The systems softwareincludes 3 K of PROM and a minimumof 33 K bytes of programmable memory,expandable to 64 K. The systems includean IBM compatible dual diskette drive,offering 512 K bytes of on line storage.A second dual drive can be mounted inthe tabletop cabinet for a total of I MBof on line storage. The diskette drivesfeature voice coil positioning and motor-ized loading and unloading of diskettes.

All the Z//100 systems are availablewith a monitor, a complete file manage-ment system and (at extra cost)FORT//80, the company's previouslyannounced 8080 resident FORTRAN IVcompiler. FORT//80 is a subset of ANSIFORTRAN IV, producing directly ex-ecutable optimized 8080 machine code.FORT//80 (including IBM format float-ing point) requires 11 K bytes of mem-ory. It includes a number of languageextensions which allow the user to takemaximum advantage of the 8080 hard-ware. These include program controlover interrupts and 8080 flags, directFORTRAN addressing of 8080 ports,and the ability to link in line machinecode into a FORTRAN program.

The Z//100-1 is a timesharing re-placement system. Priced at 57995, itincludes 36 K bytes of programmablememory, dual diskette drive and twoEIA RS-232-C serial communicationschannels. One channel can be orderedwith a 20 mA current loop interface fora Teletype. According to the company,this system is designed to allow users to

merely unplug their terminal from theiracoustic coupler, plug it into theZ//I00-I and begin developing applica-tion programs using FORTRAN as a highlevel language.

The Z//100-2, priced at $8995, in-cludes 34 K bytes of programmablememory, dual diskette drive, and a 60character per second bidirectional lineprimer (80 column friction feed stand-ard; I 32 column tractor feed optional)and keyboard.

The top of the line Z//100-3, pricedat $9795, includes 33 K bytes of pro-grammable memory, dual diskette drive,a 1920 character CRT display and key-board, and an RS-232-C serial commu-nications channel. An optional 300 linesper minute line printer, either 80 columnfriction feed or 132 column tractor feed,is supported by this configuration.

The FORTRAN compiler,FORT//80, is available with any of theabove Z//100 configurations, priced at$750.

Delivery is quoted as 30 days afterreceipt of order. Realistic Controls Cor-poration is located at 3530 WarrensvilleCenter Rd, Cleveland OH 44122."

An Advanced IntelligentTerminal System

Bitech Inc, 1440 S Stale CollegeBlvd, Building 6, Anaheim CA 92806,has sent along this photo of their newbrainchild: the Micro-2000 Series Dis-tributed Data Processing System. This isa self-contained operator oriented proc-essor which contains a video display with24 lines of 85 characters, a standardtypewriter keyboard with auxiliarynumeric key pad and function keys, anddual floppy disk drives seen at either sideof the display screen in this photo of theproduct.

122

Now.

THE PERFECT MICROCOMPUTER

VECUCR1

DEALERS

NORTHEAST

Computer Mart of N.Y., Inc.

314 Fifth Avenue

New York, N.Y. 10001

212-279-1048

Computer Mart of Long

island

2072 Front Street

East Meadow, N.Y. 11554

516-794-0510

Computer Mart of N.J.

501 Route 27

Iselin, New Jersey

201-283-0600

The Computer Mart

1097 Lexington

Waltham, Mass. 02154

617-899-4540

Byte Shop

1025 W. Lancaster Ave.

Bryn Mawr, Pa. 19010

215-525-7712

Personal Computer Corp.

Frazer Mall

Frazer, Pa. 19355

215-647-8460

Computer Workshop

5709 Frederick Avenue

Rockville, Maryland 20852

301-468-0455

Hoboken Computer Wks.

20 Hudson Place

Hoboken, N.J. 07030

201-420-1644

Audio Design Electronics

487 Broadway, Suite 512

New York, N.Y. 10013

212-226-2038

SOUTHEAST

Byte Shop

2018 Greene StreetColumbia, South Carolina803-771-7824

MIDWEST

Data Domain-ThePersonal Computer Stores

406 S. College Avenue

Bloomington, In. 47401

812-334-3607

7027 Michigan Road

Indianapolis, In. 46268

317-251-3139

219 Columbia

W. LafAyette, In. 47905

(itty bitty machine co., inc.)

1316 Chicago Avenue

Evanston, Illinois 60201

312-328-6800

42 W. Roosevelt

Lombard, Illinois 60148

506Vi Euclid Avenue

Lexington, Kentucky

606-233-3346

3028 Hunsinger Lane

Louisville, Kentucky 40220

502-456-5242

2221 E.Capitol

Shorewood, Wi. 53211

414-961-2430

Digital Design

7694 Camargo Rd. Madiera

Cincinnati, Ohio 45243

513-561-6733

The Micro Store

634 S. Central Expressway

Richardson, Texas 75080

214-231-1096

NORTHWEST

Byte Shop

2626 Union Avenue

San Jose, California

408-377-4685

Kentucky Fried Computers

2465 Fourth Street

Berkeley, Ca. 94710

415-549-0858

Ximedia

1251 25th Avenue

San Francisco. Ca. 94122

415-566-7472

Affordable Computer Store

3400 El CaminoReal

Santa Clara, Ca. 95051

408-249-5834

Computer Shack

1922 Republic Avenue

San Leandro, Ca. 94577

SOUTHWEST

Byte Shop of Westminster

14300 Beach Boulevard

Westminster, Ca. 92683

714-894-9131

Byte Shop

18424 Ventura Boulevard

Tarzana, Ca. 91356

213-343-3919

Byte Shop

Palm Plaza

Thousand Oaks, Ca. 91360

805-497-9595

Computer Playground

6789 Westminster Ave.

Westminster, Ca. 92683

714-898-8330

Byte Shop

496 S. Lake Avenue

Pasadena, Ca. 91101

213-684-3311

Upland Computer Labs

75 E. 9th Street

Upland, Ca. 91786

714-981-1503

Sunshine Computer Co.

20710 S. Leapwood Ave.

Carson, Ca. 90746

213-327-2118

Byte Shop of Tempe

813 N. Scoltsdale Road

Tempe, Arizona 85281

602-894-1129

Byte ShopTuscon

2612 E. Broadway

Tuscon, Arizona 85716

Byte Shop Phoenix

12654 N.28th Drive

Phoenix, Arizona 85029

602-942-7300

Bits & Bytes Computer

Shop

6819 C N. 21st Avenue

Phoenix, Arizona 85015

602-993-3622

OH g=*aphc inc.

717 LAKEFIELD RD., • SUITE FWESTLAKE VILLAGE, CA 91361

Not Affiliated With Vector General

A Hardware Simulator That'sthe Real Thing

The disk controller of the Micro-2000 has an interesting feature in its useof a 16 K byte memory buffer whichallows a full track of a standard sizefloppy disk to be transferred with asingle track reference.

This processor can be ordered withmain memory of from 16 K to 64 Kbytes, and the press release mentionsthat "the Micro-2000 will support a fullrange of peripherals such as fixed headdisks, character and line printers, 3M

cartridges and 7 or 9 track tapes, as wellas asynchronous communications at 75to 9600 bps."

The Micro-2000 is said to have acomplete BASIC language interpreter aswell as a disk operating system whichsupports sequential or random accessfiles with fixed or variable length rec-ords. An applications package orientedto business people is part of the productofferings, and delivery is quoted as 60days."

How do you get the function of a hotnew processor chip without completelyreplacing the existing processor card ofyour machine? RHS Marketing, 2233 ElCamino Real, Palo Alto CA 94306, hassent along this picture of a new Z-80conversion kit for Altair, IMSAI andsimilar .processor cards. How does itwork? This card functionally duplicatesthe external world signals of an 8080and its associated 8212 chip, interfacingthrough the sockets in which your pre-vious 8080 and 8212 circuits had beenmounted. The card is mounted "piggyback" on the original processor card,with a direct connection of the Z-80card to the original 8080 socket, and acable connection to the original 8212socket. The price of this card is quoted

YOU'LL SAY...

Vector g^aphc

WHY OUR MEMORY SHOULD RE YOUR MEMORY

1. Quality 2. Delivery 3. Price

Access Time: 450 ns - no wait statesCurrent Requirement: + 5 to + 10V at 1.6A worstcase, 1.35A typicalMemory Chips: Prime components plus two

extrasAddress Lines: Fully bufferedMemory Protect: Hardware 8KPower Regulators: 4 ea. 7805

Address Select: Dip switch accessable fromtop of board. No need toremove board to relocateOutput Disable: Permits use with transparentloaderBoard: Quality G-10 material withsolder mask both sides.Pre-tested for etch bridges.

Order your 8K RAM kit for only $265.00 +6% Cal.sales tax +3% hndlg. $350assmbld., both incl. sockets

P.O. BOX 4784

THOUSAND OAKS, CA 91359

TEL:(213) 889-9809

CCtt G3APHC inc.

123

as $159.95 in the press release wereceived, and delivery is quoted as "offthe shelf.""

Intercept This General Purpose System

Intersil Inc, has announced a newfloppy disk program development sys-

tem, 6970-1FDOS, for use with its"Intercept" IM6 I 00 CMOS microproces-sor prototyping system. This is an in-dustrial system which looks like a DECPDP-8 with disk.

The purpose of the 6970-1 FDOS is toprovide rapid software development forsystems using the IM6100 CMOS. Thedisk version uses the 4096 words ofmemory provided with the Interceptsystem and an ASCII terminal, such asTeletype ASR33 or equivalent.

The 6970-IFDOS consists of twointerfaced floppy disk drive mechanismswith all electronics, power supplies andcables necessary to add more than 4 mil-lion bits of on line mass storage to theIntercept prototyping system.

All components are packaged in onecovered enclosure which can be rack ortabletop mounted, and plugs into Inter-cept. It provides IBM 3740 compatiblemedia with multiple sources, and is fullysoftware compatible with the DEC RX8flexible disk system for the PDP-8/Eminicomputer.

The software components of theproduct include a file system, a key-board monitor, a text editor, an assem-bler, binary loader, octal debugger, highlevel language interpreter, and numerousutility programs. The entire programdevelopment syslem is available fromIntersil distributors. Price for the 6970-IFDOS floppy disk operating system is$5100. Intersil is located at 10900 NTantau Av, Cupertino CA 95014."

Want UV Light Sourcesfor Erasing EROMs?

What's the Inverse of a Clockwise Wrap?A Counter Clockwise Unwrap at theOther End of the Shaft

The Vector Electronic Co, 12460Gladstone Av, Sylmar CA 91342, hasjust come up with this latest variation ontheir battery operated cordless wirewraptool: the PI60-9 wrapping and un-wrapping tool, which when mounted inthe P160-4R cordless motor unit givesthe user both a power wrapping head(photo at right) and a power unwrappinghead. This little bit of creativity costs$18.40. It can be used by itself formanual operation, or in conjunctionwith the P160-4R power tool whichcosts $45.68. It is designed to take up lothree wrap levels of wire from 26 AWG

lo #30 AWG in si/e. The unwrappingend features a spring loaded sleeve thatretains and ejects the wire after removal,controlling the loose ends so you don'tdrop said loose ends among your wirewrapped circuits causing some randomlogic connections or worse."

Microprogramming - The Gory Details(Serious Homebrewers Take Note)

The Microprogramming Handbook byJohn R Mick and Jim Brick of AdvanceMicro Devices has just been madeavailable. Its price is $5 and it is availablefrom AMD direct (address 901 Thomp-son Place, Sunnyvale CA 94086) or fromyour friendly local distributor. Here iswhat it contains:

• A tutorial introduction to theBipolar Microprocessor concept (atrue microprogrammed machineas opposed to a tiny generalpurpose machine implementedwith LSI). This introductioncovers the idea of a micropro-gram, the concept of a controlmemory, organization of a con-trol memory, branching withinmicrosequences, overlapping in-struction fetch with execution, atypical system design for a micro-programmed CPU, etc.

• A typical computer architectureimplemented with the set of con-trol chips available from AMD.Examples of the microprogramassembler available from AMD.

• Specifications of the AMD 2900series parts.

• The high point: The complete

This handheld UV wand, availablefrom Ultra-Violet Products Inc, 5100Walnut Grove Av, San Gabriel CA91778, is but one of the black lightproducts available from this firm. Sendfor their brochure and price list onproducts which include various forms oflamps and stands, protective goggles, etc.This particular lamp was originallydesigned for use in the ultraviolet curingof certain industrial adhesives. Storesand clubs with EROM programmingservices will find this wand and similarproducts of the firm attractive for use inthe erasure of previously programmed1702A, 2704, 2708 and other EROMparts."

1

wiring diagram of a high perform-ance microprogrammed 16 bitmachine implemented with theAMD parts, contained in twoD size prints. Software hackerscan wire starting from this model,substitute programmable memoryfor the n bit by 4096 word mem-ory shown and use your old

124

microprocessor system to definecontrol memory through a "backdoor" and examine the resultswhile developing your fun newcomputer architecture.

All in all, The MicroprogrammingHandbook will make a valuable startingpoint for anyone seriously interested inusing the high speed contemporarybipolar chips to make a custom machinedesign - or an emulator of existingmachines for that matter."

Programmable Calculators at Work

Texas Instruments supplied this pic-ture dramatizing the use of the SR-S2programmable calculator's library of39 navigation programs for skippers andsailors who use celestial and coastalnavigation techniques, as well as oceansailing and sailboat racing tactical strate-gies. The price of the programs as apackage is $44.95, and the DC to DCconverter needed to run the calculator inthe field from mobile supplies of 12 VDC costs $12.95. Information requestsshould be forwarded to Texas Instru-ments Inc, Inquiry Answering Service,POB 5012, M/S 308, attention: SR-52NAC PAK, Dallas TX 75222.■

Forget About Multiple Output PowerSupplies for Your Homebrew 8080 . . .

The new DC to DC converter whichhas been designed specifically for usewith microprocessors and microproces-sor related integrated circuits has beenannounced by Reliability Inc of HoustonTX.

Model 3W 5 R12-5 is a high perfor-mance power source, providing highlyregulated +1 2 V at 200 mA and -5 V at100 mA from a 5 VDC input. Thesevoltages just happen to be the powersupply voltages required by an 8080processor in addition to the 5 V used byTTL circuitry. The outputs are said to befully short circuit protected and free ofdamaging turn on and turn off over-shoots.

The unit has low ripple and noise

(I mV RMS) and 0.02% line and loadregulation. Input to output isolation is300 V and operating temperature rangeis -25°C to + 70°C. Package size is 2.0 by2.0 by 0.40 inches. All units areencapsulated in black finished coppercases.

Availability is from stock for evalua-tion quantities and four weeks ARO forproduction quantities. For a bulletingiving full specifications and for pricing,write or call Bob Miller, Reliability Inc,5325 Glenmont, Houston TX 77036,(713) 666-3261."

Here's an Interesting Use of an 8080

Teknekron Inc of Berkeley CA hasjust introduced a new programmableinterface board intended lor a traditionalminicomputer, the Data General NOVA

,* MM I MIA

or Eclipse products. The neatness of thislittle concept lies in the fact that you'vesuddenly got a multiprocessor systemwhen you plug one of these CPI-660Aboards into the Data General product.The Teknekron interface board containsan 8080a microprocessor as its controland arithmetic element to permit cus-tomization of the behavior of the inter-face using a command interface disci-pline. Much of the detailed operation ofan interface can be performed by the IOmicroprocessor instead of the host com-puter, thus freeing computing time in

Make the HAL Connection

' 8080A MPU

» 1K Monitor/DebugSoftware in2708 EPROM or2-3624 PROMs

» On board spacefor: 4K ROM(2708),2K RAM(2102A-4)

• 24 lines ofParallel I/O (8255)• Hardware "front

panel" on board

• OptionalAccessories:

^ CRT Terminal

Board, BASIC in

EPROM, Audio

Cassette Interface,

7K RAM Expansion Board/

EPROM Programmer, Power Supply.

• TTY Current Loop or

RS-232C serial I/O (8251)MCEM-8080 from$375 (2-3624 ROM/1K RAM) or$445 as shown (2708 EPROM/2K RAM)

and solve your lab or OEM computer problems

1. Connect to the 24 lines of Parallel I/Oand ASCII or Baudot Serial I/O.

2. Connect to processor bus to add mem-ory expansion board/EPROM program-mer, I/O devices, or our unique CRTTerminal Board.

3. Connect to our power supply or useyour own.

Lab users and OEM's alike will find solu-tions to their computer problems with theMCEM-8080 computer. All essential com-

puter system elements are incorporated inthis fully assembled, tested single-boardcomputer. Some unexpected features ofthe HAL MCEM-8080 are: hardware "frontpanel" which allows setting a breakpointand manual control of the computer; 1KROM Monitor/Debug Software (with usercallable, Intel compatible I/O routines)which greatly simplifies program develop-ment; Parallel and Serial l/Oon the board;and very reasonable prices.

Call or write for further information on the HAL Connection.You'll be glad you did!

HAL COMMUNICATIONS CORP.

Box 365B 807 E. Green Street, Urbana, III. 61801

Telephone (217)367-7373

125

the host computer for better uses likenumber crunching. This is hardly a per-sonal computer product, but thosereaders who are involved in system de-sign and integration may find this prod-uct of interest. Contact Teknekron at211 8 Milvia St, Berkeley CA 94704."

Want an LSI-11 in a Desk?

Digital Equipment Corp gives you theoption to get an LSI-11 with 32 K bytesof programmable memory, 512 K bytesof floppy disk mass storage on two

drives, a VTS2 video terminal and anLAI 80 dot matrix printer. The wholesystem is aimed at the business personand comes with high level languagesoftware of DEC's "DIBOL" language.It's at a business person's price, too,starting at $20,900 for the configurationjust described. But if you're looking foran LSI-11 development system or acomplete and cheap PDP-I 1 system -and you have the money but not ihetime to configure it yourself, then thismight be an attractive option. For thisproduct, write Digital Equipment Corp'sCommercial Products Group (MaynardMA 01754) and ask for information onthe 320 Series of DEC Datasystems."

Here's an Umbilical Cord forYour Microprocessor . . .

AP Products, Box 110, 72 CorwinDr, Painesville OH 44077, has just intro-duced a new Test Clip J umper Assemblywhich is used in conjunction with their40 pin dual in line package test clip as

Here's a Neat Concept — ForHard Surface Disk UsersWith Butterfingers

The "Shockwatch" is an impactrecorder for use on front load diskcartridges. It will change in appearancefrom clear to brilliant red if subjected toa mechanical shock or force greatenough to cause a malfunction of thecartridge. Instructions are clearly shownon the label directing the operator torefrain from using a questionable car-

Here's an Interesting FrontPanel Concept

For those interested in the details ofsingle step operation of software, Elec-tronic Products Associates Inc has justannounced a new feature, called the"Data Catcher," to their Micro-68 line ofprototype development systems. Thisfeature will enable the user to capturethe address and operand after the com-pletion of each machine instruction anddisplay the data on its integral 6 digithexadecimal display. The option ispriced at $14 0 and works with thecompany's "Expanded —68" micro-computer system. This kind of operationis extremely valuable in educational and

shown in this photograph. The jumperconnects the lest clip to a test system viaa 40 wire flat cable. AP gives several ter-mination options to the test equipmentmanufacturer who would use this item:no termination, double row 0.1 inch(0.254 cm) matrix socket connector,card edge connector, printed circuit con-nector, dual in line plug connector, etc.This product's intended use is as theumbilical cord connecting an automatictesting device to a 40 pin package in thesystem under test. The test clip is con-nected directly to the package in thesystem under lest, and the contacts onthe test clip are routed to Ihe cor-responding wires on the cable. The testclip jumper and 12 inches (30.5 cm) ofribbon cable ending in a 40 pin doublerow 0.1 inch matrix socket connector asshown here cost $13.88 in quantities of10; to this must be added the TC-40 testclip itself which costs $21 in quantitiesof 10. AP will cut the ribbon cableoptionally to any length desired,rounded to the nearest half inch incre-ment, presumably with a variation inprice which is a function of length.*

tridge. According to the press release,the Burroughs Corporation has adoptedthe Shockwatch for use on all B9385-3disk cartridges.

It is intended to eliminate down timeand prevent head crashes, job reruns,data loss, and the general reduction inoperating efficiency which accompaniesthese occurrences. Information is avail-able from Media Recovery Inc, Box 867,Graham TX 76046.■

learning situations, as well as when de-bugging or checking out small segmentsof production program code which mustbe highly optimized. For further infor-mation, contact Electronic ProductAssociates Inc at 1157 Vega St, SanDiego CA 921 10.■

The OPUS/ONE Language . . . Continued

Administrative Systems Inc, 222 Mil-waukee, Suite 102, Denver CO 80206,has just forwarded us a copy of theUser's Manual for the OPUS/ONElanguage. This manual accompanied apress release which updates the terms ofthe product offering (see page 96 ofDecember 1976 BYTE) and announcesthree Altair compatible versions of thelanguage. This interpretive compilerproduct gives the user a high levellanguage facility which is comparable inmany respects to ALGOL or FOR-TRAN, yet retains the simplicity ofinteractive BASIC. The new Altaircompatible versions are expected to bereleased in the first quarter of 1977(about the time you're reading this), andthe price of the language has beendropped to $99 — with refunds going toall previous purchasers who paid $250 or$300 which was the previously an-nounced price. It is available in thefollowing three MITS Altair compatibleforms:

126

V. SJWPIJi

iOBT PHOGIIAH

lo bin hi r.oi i

SDK

40 UK SI PRIM1 ■30 GCSlff •K1HI f.10 LCOr [. HO 4?

»0 LIN 71 PRINT 'IOO COSH* 'I'KINt

;:

".'.?•* „,

130 LOOt I. ITO !

\on> j

HE

tOI

160 MtUKH 1

ORIGINAL NUMBERS:

. IB4S .B?7| .6?7.4405 .104* .09*.47J0 .7102 .081.0443 .4329 .480

:SI

.4;

10 .34TB .46311' .10?] .744'

3200

3384

sorted mmiCKsi

•OlSt .0164 .0o41 .0443

.4»n .47JB .480? .;?Ba

is!

7i .rio? .;;30

7? .4343 .454B71 .8391 .BBI4

£8

»

3384

BYTEs Eite

Don't Miss the MACC Computerfest 77

777£ following notice was receivedfrom MACC as this issue was going topress . . .

A large flea market will be among theattractions at Computerfest 77, thesecond annual Midwest Regional Com-puter Conference for hobbyist comput-ing. Sponsored by the Midwest Affilia-tion of Computer Clubs, an organizationof amateur computing clubs in ten

•Paper tape form, loaded using a

MITS 2SIO board at ports 0 and

1.

•Audio cassette form, loaded

using a MITS ACR board at ports

6 and 7.

•Floppy disk form, loaded using

the MITS controller at ports 10,

11 and 12.

All three versions use a MITS 2SIOboard or 4PIO board interfaced to anASCII terminal to accomplish initializa-tion using an interactive sequence.Memory requirements are 8 K for thepaper tape and audio cassette forms, and12 K for the floppy disk version.

Whichever form you use, you get alanguage which features multiple preci-sion arithmetic up to 126 decimal digits,strings both as procedure names and as adata type, variable names of unrestrictedlength, up to 255 dimensions to arrays[but who has got enough memoryaddress space to use them all?),numerical or string data types, formatted10 statements and a block structuresimilar to the ALGOL BEGIN . . . ENDblock. To give you an enticing sample ofwhat OPUS/ONE is like, we've repro-duced the sample program from page 85of the OPUS/ONE User's Manual toillustrate its features."

THEFRONTRUNNER

Equinox IOO isthe8080 CPU/S-IOOBus computer kit that's years infront of Altair* and IMSAI in design,function, and front-panel programmingcapability. Equinox IOO is easier to build, easier to program, easier toexpand, in the future and completely debugged right now. After all, it's fromPARASITIC ENGINEERING .the leading supplier of debugging kits for theAltair 8800. Before you invest in any micro-processor kit; discover the newEquinox IOO. At $599, it's clearly the Frontrunner.Write for free specs:

PARASITIC ENGINEERING RO. Box 6314, Albany California 94706

*Altair is a trademark of M.I.TS. Inc. PwSS

127

neighboring states and Canada, theconvention will open on June 10 at theBond Court Hotel in Cleveland OH.Computerfest 77 will be a completeconvention with workshops, manufactur-ers' exhibits, a flea market, seminars andtechnical sessions open to all attendees.MACC is a volunteer, nonprofitorganization. "Our intention is simply tobring together the buyers and the sellers,the hobbyists and the manufacturers,and have some fun doing it," says GaryColeman, president of MACC. The ticketprice is $2 for all activities, includingseminars. MACC is also working onchartering a plane flight to Dallas for theNCC show's activities the week followingthe Computerfest. Additional details onComputerfest 77 and the NCC charterflight are available from Gary Colemanat the Midwest Affiliation of ComputerClubs, POB 83, Cleveland OH 44141."

The Caseof the Missing Trigonometry . . .

Due to an oversight of coordination,the equations accompanying figure 2 ofRobert Grappel'S article on page 34 ofMarch 1977 BYTE were omitted. Thetrigonometry of the model aircraftservo plotter is as follows:

Equations (R = arm length)

(X, Y) = ((Xfl + X(b), (Ye + Ya))

0'

-R SIN (0)= -R SINR SIN (0 -90°) = -R COS (0)

X^ = R COS (0 + 0 -90°) = -R SIN (0 + 0)

BYTEs Bugs

<0 = R SIN (0 + 0 - 90°) = R COS (0 + 0)

Applying the above gives

X = -R (SIN(0) + SIN (0 +0))Y = R ( - COS(0) + COS (0 +0)

There is no unique solution for (0, 0) coordinatesexcept at extremes. ■

SOME NOTES ONANALYSIS OF PLOT ANGLES

Errors in the MIKBUG Roadmap

Thanks to Douglas B Brumm PhD,224 Hecla St, Lake Linden Ml 49945,for pointing out some glitches in theMIKBUG roadmap article, page 96, inthe February 1977 issue. The followingare his findings:

•Table 1, page 98, OUT2H entry:The text should read "Hex byteoutput: The data at the locationpointed to by the X register is sentto the terminal as two hexadecimaldigits."

•The entry point of the print dataroutine is PDATA1. The PDATA2entry should be changed toPDATA1 with address E07E intable 1."

The following letter is self-explana-tory and concerns inverting the calcula-tion shown above.

I am a recent subscriber, and havenow read three issues of your magazine.I have found your articles both informa-tive and practical. I have been involvedwith computers for 16 years and haveobserved a wide range of abilities andattitudes among people in the field. Thesomewhat naive approach frequentlytaken by computer hobbyists oftenenables them to succeed where computerscientists with more classical approacheshave failed.

With reference to figure 2 on page 34,March 1 977, you indicate the need for areiterative calculation to solve for thetaand phi for your servo plotter. Here, youare guilty of assuming that there is no

direct solution when there really is one.The solution may take many forms, butassuming an arcsine function is available,which produces results in degrees from-90 to +90, the following FORTRAN-like statements will be well-behavedexcept at the origin:

RHO=SQRT(X*X+Y*Y)PSI=ASIN (Y/RHO)XI=ASIN (RHO/ (2.0*R) )PHI=180.0-2.0*XITHETA=PSI+XI

Note that 2.0*R may be entered as aconstant or precomputed once in theprogram. Also note that standardFORTRAN would require converting thearcsines from radians to degrees bymultiplying by the constant 180.0/pi.You might also want to leave all theangles in radians, in which case the 180.0would be changed to pi, since the angleswill be rescaled before being output tothe servos anyway.

Theta and phi should be rangechecked to avoid overdriving the servos.There may also be some mechanicalinterference to avoid, depending on thedesign. These interference problems maybe eliminated if the servos are mountedwith their shafts downward. Servo 1would be suspended from a supportanchored to the left or lower left of theorigin. Servo 2 would be suspended fromservo 1's arm. Miniature casters or someother form of support should beprovided at servo 2 and near the pen.

If for some reason it appears desirableto use two arms of different lengths, theangles can still be found in closed form,although the calculation is slightly morecomplicated.

Keep up the good work.

Ronald M Martin, President

Martin Associates

POB Ml124

Ann Arbor Ml 48106.

,___...„«„. _ «_ . _.«»»——.«,»» ■*■** 400 North Washington Street, Suite 200

INTERNATIONAL DATA SYSTEMS, INC. Fans church, Virginia 22046 usa

Telephone (703) 536-7373

S100 Bus Cards (ALTAIR/IMSAI Compatible)

USES

KIT PRICE

88-SPM Clock Module

Your computer keeps time of day regardless ol what program it isexecuting. Applications include event logging, data entry, hamradio, etc.

$9600

88-UFC Frequency Counter Module

Measure frequencies up to 600 MHz Computer can monitormultiple frequencies such as transmit and receive frequency.

$149.00

88-MODEM Originate/Answer MODEM

Use your computer to call other computer systems such as largetimesharing systems Also allows other computer terminals to"dial-up" your computer

$199,00

GENERAL PURPOSE PERIPHERALS

MCTK Morse Code Trainer/Keyer

Hardware/ Software package which allows your computer to teachMorse Code, key your transmitter, and send prestored messages.

$29.00

TSM Temperature Sensing Module

Use it to measure inside and/or outside temperature lor comput-erized climate control systems, elc.

$24.00

DAC8 Eight Bit Digital to Analog Converter

Requires one eight bit output port. Use it to produce computer

$19.00

Terms: Payment with order. Shipment prepaid. Delivery is slock to 30 days. Write or call for detailed product brochures.

128

BITS

TM

— Game Playing With Computers by

Donald D Spencer, published by Hayden.What does it mean to play games using acomputer? Read this book to get anintroduction into numerous recreationaluses of the computer to program and playmathematical and logical games. Topicsinclude numerous mathematical problems,casino games, board games, unusual gam-bling games, and miscellaneous logic games.Numerous BASIC language programs andlistings are included to show details. $16.95.

Scientific Analysis on the Pocket

Calculator by Jon M Smith, published byJohn Wiley & Sons. This book is another ina set of source books for mathematicalanalysis using the contemporary products oftechnology. It is oriented to the pocketcalculator, yet it will provide you withalgorithms and methods useful with anypersonal computer which implements thescientific and analytical functions found ona good pocket calculator. For a morecomplete description, see the book reviewon page 120 of the December 1976 BYTE;or order its 392 pages of detailed technicalinformation and review its use for yourself.S13.75.

mnunroM'

h

Build Your Own Working Robot by

David L Heiserman, published by TabBooks. This book will not tell you how tobuild Robbie, the robot of ForbiddenPlanet, or a classical android of sciencefiction. What it will introduce you to is theproblems of making a robot mobile devicecalled Buster III, using pre-microprocessorTTL integrated circuits for all logicfunctions. It is a must book for backgroundreading, but much of the logic can beextremely simplified using today's micro-processor technology. Use this book as afirst look at these problems from which youcan build further and more elaboratesolutions. Softbound, S5.95.

A Dictionary of Microcomputing by

Philip E Burton. In the opinion of BYTE'seditor, Carl Helmers, "This is one of thebest designed and executed dictionaries ofcomputer related terms yet seen on themarket. It is of particular relevance to thoseindividuals who want a good generalreference to numerous technical terms,broadly covering hardware and softwarefields as currently practiced," This newhardbound edition is part of the GarlandReference Library of Science and Technol-ogy. $12.50.

Software Design for Microprocessors.

This stand alone guide to microprocessorshas been designed by the people at TexasInstruments to convey knowledge to thefirst time user of microprocessors. Thisexcellent source book of computer conceptsbegins with an outline of the basic principlesof the general purpose computer, itsmachine architecture, software, and meth-ods of addressing. It proceeds to discusshow to build software, what is involved indocumenting what you've done once you'vedone it, the mechanics of programming, andspecific examples using the Tl TMS-1000,TMS-8080, TMS-9900 and SBP0400 de-signs. You'll find a thick hardcover text-book filled with over 370 pages of usefulinformation including a comprehensiveglossary of microprocessor terminology,among several other detailed appendices.$12.95.

Send to:

BITS, Inc70 Main StPeterborough NH 03458

Check payment method:

My check is enclosed

Bill my MC No.

Bill my BAC No.

Exp. dateExp. date

Total for all books checkedPostage, 25 cents per book

for books

Grand Total

$$

Name

Address

City

State

_?1P_

Signature

You may photocopy this page if you wish to leave your BYTE intact. Please allow six weeks for delivery.

Digital Computer Fund-amentals by Jefferson C Boyce.The way to a world of learning isthrough books. A great place to start,and to return from time to time, isthe classical textbook. This newbook from Prentice Hall is in-tended as just that. Topics coveredinclude digital computer operation,basic computer circuits and concepts,Boolean algebra, implementing com-puter operations in hardware, com-municating with the computer andrelated issues of coding schemes,detailed discussions of the controlsection, memory functions, arithme-tic and logic functions, input andoutput functions of a classical com-puter, a chapter on computer pro-gramming and a final summarychapter on the details of a typicalminicomputer design interpreted inthe light of the more theoreticalgeneral concepts in the book. Thisbook is excellent background infor-mation for the literate and well readhacker. Order yours today. $15.95hardbound.

Adam Osborne's books An Introductionto Microcomputers, Volumes 1 and 2, are a

concise compendium of the technical detailsof microprocessors at the component(engineering) level. These are the sourcebooks for the system designer who plans toemploy the microprocessor, or the advancedhomebrewer who wants a dash of custom-ization not found in commercial products.

Volume 1 is subtitled "Basic Con-cepts." This is the book which presents aframework of ideas concerning the designand use of small computers implementedwith LSI. Topics include definitions of themicrocomputer, fundamental concepts oflogic and numbering characteristics ofinstruction sets, etc. $7.50.

Volume 2 is a much thicker (895

How to Buy and Use

Minicomputers and Microcomputers

by William Barden. People have oftenasked us where to turn to get anintroductory book about computersfor personal use. One excellent placeto start is How to Buy and UseMinicomputers and Microcomputers,William Barden Jr's instant summaryof the small computer revolution,published by Howard Sams in mid-1976. This is one of the first booksof the "general introduction tocomputers" genre to be publishedwith an emphasis towards the smallcomputer and personal computing asit is being practiced these days, thebook, written for the novice as wellas the expert, surveys the technicaldetails of the field in nine chaptersand 10 appendices. This book is light(but essential) reading for the experi-enced computer person, and worthyof serious, concentrated perusal bythe novice. S9.95.

at4

; HowtaBuyfiUoe

: ..RIMCDKIPUTERBSMRQGDIMTEnS

page) detailed volume which complementsthe information in the first volume. This isthe volume which fills in many of the detailsleft out of the conceptual treatment inVolume 1. Here you'll find 19 detailedchapters on the engineering and logicalspecifications of products made by 16different manufacturers, including in manycases reprints from the manufacturers'documentation as well as new materialsprovided by the author. Published in 1976,it even includes such processors as theMicroNOVA by Data General and the TexasInstruments TMS-9900 as well as the older 8and 16 bit machines. Organization is bydesign type, and where parts of severalmanufacturers were intended for a givenprocessor design such as the 8080, these aregrouped into a single chapter. $12.50

KfttPHWEIZTNEALIM

COMPUTERPOWER

ANDHUMANREASON

f ROM lUIJCMENtTOCAiallATlON

L

^Computer Power And Human

Reason by Joseph Weizenbaum. Thisbook is one which should bepurchased or read for several reasons.If you're presently a programmer bytrade or skill, you'll see a philosophyof computer use and abuse pro-pounded. It's genuinely interesting,and definitely provocative if youreference the storm of letters, coun-ter letters and counter counter letterswhich this book produced in theAssociation for Computing Machin-ery's SIGART newsletters during1976. If you're a novice to the field,the tutorial and explanatory chaptersof this book, which are aimed at thelayman, will serve as an excellentbackground source which is alsoeminently readable This includes anexcellent and low level explanationof what an algorithm is, and howcomputers go about executing effec-tive algorithms. $5.95 softbound.

Send to:

BITS, Inc70 Main StPeterborough NH 03458

Total for all books checkedPostage, 25 cents per book

for books

Grand Total

Check payment method:

My check is enclosed

9K Bill my MC No.

Bill my BAC No.Name

Address

s

City

Exp. date_Exp. date

State

Zip

Sig nature

You may photocopy this page if you wish to leave your BYTE intact. Please allow six weeks for delivery.

A BIT More

When you build a project, you need information. Allyou find in the advertisements for parts are mysteriousnumbers identifying the little beasties... hardly the sortof information which can be used to design a customlogic circuit. You can find out about many of thenumbers by using the information found in these books.No laboratory bench is complete without an accompany-ing library shelf filled with references.

Order these absolutely essential references from Texas Instruments today:

The TTL Data Book for Design Engineers, $4.95, new second edition.

The Linear and Interface Circuits Data Book for Design Engineers, $3.95.

The Semiconductor Memory Data Book for Design Engineers, $2.95.

The Transistor and Diode Data Book for Design Engineers, $4.95.

The Power Semiconductor Handbook for Design Engineers, $3.95.

Understanding Solid State Electronics, $2.95.

The Optoelectronics Data Book for Design Engineers, S2.95.

Designing with TTL Integrated Circuits, edited by Robert L Morris

and John R Miller, published by McGraw-Hill, $26.

The TTL Cookbook by Don Lancaster, published by Howard W

Sams, Indianapolis. Start your quest for data here with Don'stutorial explanations of what makes a TTL logic design tick. 335pages, $8.95.

—Microcomputer Design by Donald P Martin. Edited and publishedby Kerry S Berland, Martin Research. Purchase your copy of thedefinitive source for circuitry and hardware design information onthe 8008 and 8080 computers today. Even Intel, the originator ofthe microprocessor revolution, is hard put to compete with thewealth of information found in Martin Research's new secondedition of Microcomputer Design. This is the book which wasoriginally published as an expensive (but quite practical) engineeringreport in loose leaf form, at about the time the microprocessortechnology was first catching on in the form of the 8008. This 388page second edition of the manual is loaded with detailedinformation on how to build and use computers based on the 8008and 8080. $25.

Send to:

BITS, Inc70 Main StPeterborough NH 03458

Check payment method:

My check is enclosed

Bill my MC No.

Bill my BAC No.

Exp. dateExp. date

Total for all books checkedPostage, 25 cents per book

for books

Grand Total

$

$

Name

Address

City

State

_Z±P_

Signature

You may photocopy this page if you wish to leave your BYTE intact. Please allow six weeks for delivery.

All This Just to Print a Quotation Mark?

David Chapman

Western Reserve Academy

Hudson OH 44236

It is remarkable how much trouble aminor fault in the design of a computersystem can cause. An example that I haverun up against is the virtual impossibility ofprinting a quotation mark in several versionsof BASIC with any degree of efficiency. Theversion of BASIC I presently use is DigitalEquipment Corp's EDUSYSTEM 25 BASIC,but I've found the same nit in several otherBASIC interpreters.

Suppose it is necessary that the followingstring be output:

IN BASIC, THE QUOTATION MARK(") IS A DELIMITER.

On a cursory examination, it may appearthat all that is necessary is:

10 PRINT "IN BASIC, THE QUOTA-TION MARK (") IS A DELIMITER."

There is a problem here, however. Thesecond quote, the one in parentheses, will beinterpreted as indicating the end of the

GLOSSARY

Argument:

The argument or arguments of a

statement or function is the value

or values which it acts upon. For

example, in the expression SIN

(2*X), the argument of the SIN

function is 2*X.

Delimiter:

A delimiter is something, usually

a special character, which tells the

language program where some-

thing begins or ends.

* Idiot proof:

An idiot proof system is one

which not even a genius can mess

up.

* Good guy

A system that is both idiot proof

system:

and easy to use and learn about.

Literal string:

A chunk of text which is to be

used just as it appears in the

program.

*Very important terms . . .

string. The interpreter is then left with theunexecutable:

) IS A DELIMITER."

and types out an error message.

There are a number of ways to get aroundthis problem. One is to substitute singlequotes for double quotes in output stringsand hope that the user will understand thatthey are really double quotes. This is fine forsome things, but not for others, like goodguy systems in which it is assumed that theuser knows absolutely nothing and thatsubstitution would result in confusion.

In this case the programmer finds him/herself confronted with the problem some-times known as delimiting the delimiter. InBASIC, as you may have gathered, thequotation mark is a delimiter: the delimiterfor a literal string; which is to say that itindicates where the string begins and ends.Another example of a BASIC delimiter is thecomma, which is used to separate the argu-ments of functions and of INPUT, READ,DATA and so forth.

The problem is separating delimiters fromthings delimited which look like delimitersbut aren't. One possible solution, unfor-tunately not available in any BASIC imple-mentation that I have seen, is to use twodelimiters for the same function. For exam-ple, in SNOBOL, the two literal stringdelimiters are the single quote and thequotation mark. Hence, using a, similar ploy,our example could be coded as:

'IN BASIC, THE QUOTATIONMARK(") ISA DELIMITER.'

The other possible solution is to use aroundabout method, printing the quote out-side the string. One way of doing this is touse the BASIC CHR$ function. The CHR$function reduces its argument to a binarynumber and then dumps it on the outputdevice. Since the 7 bit ASCII for a quote is0100010, or decimal 34, we can say:

10 PRINT "IN BASIC, THE QUOTA-TION MARK ("; CHR$(34); ") IS ADELIMITER."

132

10 REMARK THIS IS THE PROGRAM WHICH INITIALIZES THE

20 REMARK FILE. IT ONLY NEEDS TO BE RUN ONCE.

30 OPEN "FILE" FOR OUTPUT'THIS DESIGNATES THE OUTPUT FILE.

40 PRINT#, CHRSI34) 'PUT A QUOTE ON THE FILE.

50 CLOSE'CLOSE THE FILE.

Listing la.

10 REMARK THIS IS THE MAIN PROGRAM, WHICH PRINTS THE QUOTE.

20 OPEN "FILE" FOR INPUT

30 LINPUT#,A$ 'THIS SETS A$(1) EQUAL TO A QUOTE.

40 A$=A$(1) ' "A$" IS SHORTER THAN "AS(D".

50 PRINT "IN BASIC, THE QUOTATION MARK ("AS") IS A DELIMITER."

60 REMARK THAT IN LINE 50 THE SPACES AND SEMICOLONS ARE

70 REMARK OMITTED, ALLOWABLE IN THIS BASIC BECAUSE THEY

80 REMARK ARE REDUNDANT DELIMITERS!

Listing lb.

Listing 1: This is the final method needed tooutput a quotation mark using the DECEDUSYSTEM 25 BASIC. The program ofla sets up a file and puts the quotation markin the file. The listing of lb uses the file toactually output the quotation mark. In thisvariant of BASIC, a single apostrophe beginsa comment field on a line, avoiding the needof the word "REMARK" in many cases!

This works, but burns time, lineprinterpaper, core space and finger tips if usedoften. The obvious thing to do would seemto be to assign a string variable the value of aquotation mark, so that such a line as thismight be used:

20 PRINT "IN BASIC, THE QUOTA-TION MARK ("; A$;") IS ADELIMITER."

but this causes the same old problem if oneuses:

10A$=" ""

and furthermore, most BASICs will notallow CHR$ except in PRINT statements.

One way to get around this BASIClimitation is to ask the user to type aquotation mark and input it as a stringvariable at the beginning of the program:

10 PRINT "PLEASE TYPE AQUOTATION MARK (";CHR$(34);")";20 INPUTA$

30 PRINT "IN BASIC, THE QUOTA-TION MARK ("; A$;") IS ADELIMITER."

This, however, is not idiot proof. Toremove, or at least isolate, the idiot from thesystem, we can use a separate program, runonly once, which puts a CHR$(34) onto amass storage file. The main program canthen open the file later and get the quoteback.

This is very devious, but worse is yet tocome. In the BASIC that I use, EDUSYS-TEM 25, it is apparently impossible to inputa quote, from either a file or a keyboard!For some reason known only to the savantsat DEC it is possible to use anotherstatement, called LINPUT, to define thequote. In EDUSYSTEM BASIC, strings arelimited to six characters in length. LINPUT,short for line input, sets up an array inwhich each element but the last is a string of

length six, and in which the last element is astring which contains whatever is left over.Listing I is a final solution in EDU-SYSTEM 25 BASIC. ■

The Moral

All this, just to print a quotation mark!Similar, nitty details are often found in anylarge piece of software — it's in the nature ofthe beasts. Use of a program often requiresadaptability and ingenuity!

SOFTWARE

TEXT EDITING SYSTEM

TSC'S 6800 TEXT EDITING SYSTEM SURPASSES ALLMICRO EDITORS. THE COMPLETE ASSEMBLED SOURCELISTING NOT ONLY INCLUDES THE USUAL EDIT FEA-TURES. BUT ALSO BLOCK MOVES. BLOCK COPIES.OVERLAYS. AN EXTENSIVE CHANGE COMMAND. ANDTABS. JUST TO NAME A FEW. THIS IS THE EDITORFOR THOSE WITH SERIOUS NEEDS. SL68-24 $23.50

6800 8080 6502

8080 GAME PACKAGE I. PD80-1 $19.95

6502 GAME PACKAGE I. PD65-1 $19.95

6800 GAME PACKAGE I. PD68-1 $16.50

6800 COMPLETE SOFTWARE PACK. PD68-3 $35.50

6800 SOURCE LISTINGS

SPACE VOYAGE. SL68-5 $12.00

FLOATING POINT PACKAGE. SL68-4 $6.50MICRO BASIC PLUS. SL68-19 $15.95

PROGRAM OF THE MONTH CLUB

RECEIVE 1 YEAR MEMBERSHIP INCLUDING A MONTHLYNEWSLETTER DESCRIBING TSC'S LATEST SOFTWARERELEASES. UP TO A 15/. DISCOUNT OFFERED ONFEATURED SELECTIONS. POM $2.00

ORDERING INFORMATION

PLEASE INCLUDE 37. POSTAGE. INDIANA RESIDENTSADD 4/ TAX (US FUNDS ONLY). CHECK YOUR LOCALDEALER FOR OUR PRODUCTS. (DEALER INQUIRIESWELCOMED). SEND $.25 FOR A COMPLETE CATALOG.

Tnn TECHNICAL SYSTEMS CONSULTANTS TGI""

I •JLl sox ES7H H. LBFBYETTE INDIHNfl 47906 ' OLl

133

Personal Computing

It's

at the Dallas Convention Center

Big Plans for "Big D"

Innovation and relevance are key words for the 1977 National Computer Conference, thefirst NCC ever held in the Southwest and the year's largest gathering anywhere of dataprocessing users, computer professionals and computer hobbyists. More than 25,000 peo-ple are expected to gather in Dallas for a conference program of more than 100 sessionsand the year's largest display of computer hardware, software, systems and services—plusthe first National Programming Contest and a series of outstanding Professional Seminars.

Largest Computer Exhibits Ever

More than 250 major hardware and software companies will pack more than 1,100 boothsinto the Dallas Convention Center's modern 200,000-square-foot main hall. And addition-al space for the Personal Computing Fair & Exposition is on the next level for a totallyseparate exhibit by commercial producers of Personal Computing hardware and software.For information on exhibiting in either area, please contact Ms. Carol Sturgeon, manager,conference operations, National Computer Conference, 210 Summit Ave., Montvale, N. J.07645,201/391-9810.

Headquarters Hotel

Personal Computing headquarters for the 77NCC will be at the Holiday Inn in downtownDallas. Low-cost housing also will be available at Southern Methodist University. Fill inthe coupon for information about NCC's Deluxe Travel Service, which can take care of allof your travel and housing reservations for you in one neat package. Or, contact 77NCC,c/o American Federation of Information Processing Societies, Inc., 210 Summit Ave.,Montvale, N. J. 07645, 201/391-9810.

For More Information!

To: 77NCCc/o AFIPS210 Summit Ave.

Montvale, N.J. 07645

Yes, I am very interested in the 77NCC and the Personal Computing Fair &Exposition. Please keep me informed about the conference program, exhibitsand all related activities and events, and please send me information about:

I ) Exhibiting my personal computer system

1 1 Exhibiting my company's commercial products/services

[ I Personal Computing Fair & Exposition events

| j The first National Programming Contest

1 ) Professional Seminars

I | NCC's Deluxe Travel Service

| J Low-cost housing at SMU

I I And, I'd like to receive your bi-monthly newsletter, NCC ROUNDUP!

Company/school: _Street address:

City, state, ZIP code:

0)

Goes National

during the 1977 NCC, June 13-16

Personal Computing Fair & Exposition

The fast-growing field of Personal Computing will share the national spotlight in June,when the 77NCC will recognize the dynamic growth and promise of the field with thePersonal Computing Fair & Exposition. In addition to the commercial exhibits of PersonalComputing manufacturers, dynamic displays and demonstrations of non-commercial indi-vidual and group-owned projects will be featured at the Dallas Convention Center. Thesuccess of other hobbyists can give you new ideas for your own systems, "how-to" tipsand dozens of clever solutions to everyone's problems. You might even find a joint-venturepartner with a kindred spirit. More than 100 non-commercial small computing systemsare expected, featuring hardware and/or software implementations, games, recreation,music, art, amateur radio, scientific, miscellaneous and general applications. Prizes andawards will be given in all categories.

Personal Computing Program

Two full days of panel sessions on June 15 and 16 will provide an in-depth look atPersonal Computing: Past, Present and Future; The Future of Retail Computer Stores;Hardware of the Computer "Hobby" Market; and Personal Computing Software. Leadersin the Personal Computing movement will appear on each of the panels to let you knowthe latest developments in the field, point out trends you'll need to be aware of—and an-swer your questions.

Special Interest Sessions

In addition to the panel sessions, special interest groups will be able to gather informallyfor "how-to" programs on building a kit, debugging software, using assembly language,I/O interfaces, cassettes and disks, software standards and so on, into the night. If the spe-cial interest group you want is not organized when you get there, we'll do our best to helpyou get one started!

Hational Club Congress

Is a national personal computing association needed? If it is, what does it do, how does itdo it, and who does it? To find out what's happening—pro and con—club reps from acrossthe nation will gather to exchange ideas and discuss issues related to club activities and pro-grams. Make certain your club sends an official delegate who can speak for you and votevis-a-vis a national organization, establishment of national hard ware/software standards,a national program library and interchange, educational seminars, meetings, ad infinitum.

1977 NATIONAL COMPUTER CONFERENCE

Dallas Convention Center • June 13-16

8080 Programming Notes

Paul Krystosek57 N LincolnLombard IL 60148

John McCarty5412 N Arrow DrPeoria IL 61614

linenumber

1234

label

With a couple of exceptions the 8080microprocessor instruction set primarilyoperates on eight bits at a time. But withsome imagination several 16 bit operationscan be performed by using these exceptions.The basic technique is to use the HL registerpair as an accumulator rather than as anaddress and index register. The simplest 16bit extension is just a different name for theDAD H instruction. The effect of thisoperation can be stated in three ways:

A Add the HL register pair to itself.

B Multiply the HL register pair by

two. (We might rename it M2HL.)

mnemonic

DAD HJNC DONEINX HDONE EQU *

commentary

HL: = HL+HL;

go to DONE if carry is zero;

HL: = HL+1;

first line of routine DONE;

Listing I: Performing a 16 bit rotate left using the HL register pair. TheDAD H instruction will shift the 16 bit number I bit to the left and deter-mine the value for the overflow flag. If the overflow flag is set, then the HLregister pair is incremented by 1.

line

number

label

mnemonic

commentary

1

LXI B,0

BC:=0;

2

LOOP

EQU *

> [main body of loop]

n

INX B

BC: = BC+1;

n+1

LXI H,-

1000

loop to stop at 1000;

n+2

DAD B

HL: = HL+BC;

n+3

JNC LOOP

go to LOOP if carry is zero

Listing 2: An example of setting up a 16 bit counter using the BC registerpair. In this example, a loop will go through 1000 iterations.

C Shift the HL register pair left onebit position. (We might rename itASLHL for "arithmetic shift leftHL")

These three statements are logically equiva-lent. To multiply by greater powers of twojust repeat the operation the required num-ber of times.

So far the DAD H instruction has beenreferred to as an arithmetic shift rather thana rotate. The carry bit is set as in a rotate,but it does not affect the low order bit. Toset up a 16 bit rotate, increment the HLregister pair after the shift if the carry bit isset, as shown in listing 1.

16 bit addition is of course done byusing the DAD B or DAD D instructionswhich exist in the 8080. In such cases, onenumber to be added is first loaded into theHL register pair, and then the other numberis loaded into the BC or DE register pair andadded to the HL register pair. A commonuse for this instruction is in index addresscalculation. A special use for this instructionis in looping and comparing. When setting upa loop using a counter which will have avalue greater than decimal 256, a multipleprecision increment operation using twosingle independent registers can be used.Note that since the INX instruction does notaffect any status bits, it cannot be used byitself as a 16 bit loop control function.

Another approach is shown in listing 2.The —1000 on line n+1 will be stored as atwo's complement number hexadecimalFC18. When adding anything less than dec-imal 1000 in statement n+2 a carry will notresult. Statements n+1, n+2, and n+3 couldbe thought of as "compare the HL registerpair to the BC register pair and jump if the

136

BC register pair is less than the HL registerpair."

If a compare high, low or equal is needed,the procedure could be extended as inlisting 3. A disadvantage of this technique isthat it requires the HL register pair to beloaded with the two's complement of thetarget number. It is probably easier andcertainly takes less execution time if we loadthe two's complement of a constant duringassembly instead of a variable calculatedduring execution.

Another modification of the loop rou-tine, shown in listing 4, can be used whenprocessing or scanning consecutive memory

locations where the end of the loop isdetermined by an address rather than acounter. An example of this is in outpultingto a port from one address to another, aswould be done when writing a block of datato tape, disk, another machine, or whatever.The (—ADR2) on line 7 may look con-fusing; it is just the two's complement of theaddress in question. While it would be slowto hand assemble such a statement, a goodassembler will do the calculation for you. Tohave variable start and end addresses thetwo's complement would have to be cal-culated by subtracting ADR2 from zero, orby a binary complement operation on the 16

linenumber label

12345

mnemonic commentary

LXI H.-1000 HLH-1000);

DAD B HL:=HL+BC;

JNC LOW go to LOW if BC register pair less than 1000;

MOV A,H )ORA L VJZ EQUAL )

HIGH EQU

EQUAL EQU

LOW EQU *

test if HL register pair equals zero;

beginning of routine if BC register pair greaterthan 1000;

beginning of routine if BC register pair equals 1000;

beginning of routine if BC register pair lessthan 1000;

Listing 3: This routine isan extension of the testingused by the routine oflisting 2. Here, the goal isto pick one of threebranch possibilities: lessthan, equal to, or greaterthan. This routine is usedto test register pair BC'srelationship to the integerconstant 1000 usingDADH with HL as a 16bit accumulator.

linenumber

12345678910

label

LOOP

mnemonic

LXI B.ADR1INCTL )

ANISTATUS >JNZ LOOP jLDAX BOUT DATALXI H.-ADR2DAD BINX BJNC LOOP

n

ADR1

EQU *

n+1

DS

n+2

ADR2

EQU *

n+3

CTL

EQU 2

n+4

DATA

EQU CTL+1

n+5

STATUS

EQU80H

line

imber

label

mnemonic

1

LXI B,-1

2

LXI H,1000

3

LOOP

DAD B

4

JNC DONE

commentary

BC:=ADR1;

loop waiting for data ready for output;

A: = BC;output data;HL: = (-ADR2);HL: = HL+BC;BC;=BC+1;

go to LOOP if address in BC register pair lessthan ADR2;

starting address;define storage area;ending address;equate CTL to 2;equate DATA to CTL+1 ;

equate STATUS to bit pattern to be comparedfrom input port;

commentary

BC: = (-1);

HL:=1000;

HL: = HL+BC;

go to DONE if carry equals zero;

JMP LOOP go to LOOP;

DONE EQU

start of routine where the loop exits to when done;137

Listing 4: This routine isbasically the same as list-ing 2 in determining whento exit the loop. The maindifference is that an ad-dress is being used insteadof an incremental or decre-mental counter. This par-ticular routine outputsdata from address ADR1to address ADR2.

Listing 5: Here is a loopwith a 16 bit counterwhich, instead of addingand comparing two num-bers to find when to exit,decrements the loopcounter and checks to seewhen it goes past zero tonegative one.

A Note About "EQU"

Throughout the listings of this article the mnemonic EQU has been usedextensively. The EQU, equate, statement is an assembler instruction or"pseudooperation" rather than a machine instruction. Pseudooperations arecommon assembler features which tell the assembler something about yourprogram or the assembly process but do not necessarily generate machine code.The asterisk (*) or dollar sign ($) (depending on the assembler that is used)indicates "this address." For example:

1) LOOP EQU *

n) JMP LOOP

The effect of statement 1 is to equate the address of the next instruction withthe label LOOP. The value of the address is then stored in the assembler's symboltable. This may seem like a trivial thing to do; but if you wanted to use your texteditor program to add an instruction at the beginning of the loop as a programpatch it can just be put there. Whereas if the label was on the first instruction thatline would have to be changed as well as the new line being inserted. [Of course ifyour text editor is capable of arbitrary insertions this is not a major point.]

Another use of the equate pseudooperation is the following:

1) CTL EQU 2

2) DATA EQU CTL+1

The effect of this would be that whenever CTL is encountered it is replaced bythe value 2. Statement 2 would equate DATA to 3 wherever it is used. The realusefulness of equates is in their ease of change at the assembly language level. Ifthe IO port address is changed, only the equate for CTL would have to bechanged to make the change throughout the program for both CTL and DATAthe next time it is assembled. Table lengths can be handled with a similar ease asshown in the listing below. In this way, if the length of the table is changed, thechange will be made throughout the program the next time it is assembled,providing of course that TLEN is used consistently.

Another handy fact is that if you have used two different spellings for thesame label or variable, one can be equated to the other rather than changing themall to one.

linenumber

123

45

label

TBL

TLEN

mnemonic

'BA' .'CD' I'FE' t

DW 'BA'DW 'DW 'DW 'HG'EQU *-TBL

commentary

define character strings; [misc data fordemonstration]

equates TLEN to the current address —beginning address;

bits followed by a 16 bit incrementoperation.

Yet another application of the doubleadd instruction with two's complementarithmetic is in decrementing a register pairwith an indication of passing zero. The two'scomplement of the number —1 is all 1 bitsregardless of how many bits are in thenumber. The only number which can beadded to —1 without causing a carry is zero.Adding —1 to a number will decrement thatnumber by one and set the carry flag unlessthe number was zero. Using these facts aloop can be set up as in listing 5.

When using this technique, the decrementand check if zero are done at the beginningof the loop as in languages like PL/I ratherthan at the end of the loop as in FORTRAN.The reason for this is that we find out when

the loop goes from zero to —I rather thanwhen it is zero. A disadvantage to thistechnique is that it ties up a register pair tohold the —1 value.

The techniques illustrated here are just afew examples of what one can come up withby using a little imagination and lookingvery closely at exactly what each instructiondoes. They are not the most general tech-niques as far as usefulness in many situa-tions, but used in the right place they cansave a few bytes or microseconds. If nothingelse, these notes have shown ways to useinstructions that may not be immediatelyobvious."

REFERENCE

Intel Corporation: Intel 8080 MicrocomputerSystems Users Manual, September 1975.

138

Here are 10 reasons whyyou should subscribe to

CREA TIVE COMPUTINGtoday.

V

4.5.

J.

Creative Computing will help youdecide which computer is best foryou.

Creative s no-nonsense equipment profiles ami yonwith the facts before you talk to the vendor or dealerWhether you're interested in a microcomputer kit amini terminal, or programmable ca culalor you IIfind the evaluative information you need in CreativeIndeed one wise hardware decision could save youHie cost of a lifetime subscription1

Creative Computing discussescomputer applications in non-technical, understandablelanguage.

Business people who want to know what s going onm the EDP department students who want to learnabout microprocessors, hobbyists looking to makegood use of home computers or anyone concernedabout the effect of the computer on society will hndthese and many, many more mind-expanding topicscovered on the pages of Cieative

Creative Computing covers com-puter education in depth.

After all. that's where we got our start and so wecontinue to present 'our or five major learning,activities every issue If you're a teacher Cieaitvewill save you hours of preparation time if you re astudent, you'll be way ahead of your class withCreative And if you've already graduated you canbone up on what you missed

Creative Computing carries out-standing fiction every issue.

Oneof the best ways of exploring future scenarios ofcomputer usage is through fiction, so Creative seeksOut material from the best authors Isaac AsimovFredenk Pohl. Arthur C Clarke to name just a few aswell as many others who are destined to be the bestof the next generation

Creative Computing's bookreviews are honest and timely.

We re not owned by a big book publisher to whomwe owe loyalty, nor do we depend upon advertisingfor our revenue Hence, not only do our reviews pullno punches, but we also rank order similar booksdike all 34 books on the BASIC language which wereviewed last year] Creative reviews virtually everycomputer book of interest to educators, hobbyistsand general lay people, even including vendormanuals and government pamphlets

An extensive resource section willsave you time and money.

Every issue of Creative carries 40 or more shortresource reviews evaluating periodicals bookletshardware, terminals, couplers, peripherals, softwarepackages, organizations, dealers and much moreEvery entry has a brief description, evaluation, andthe name address, and phone number of thevendor You'll save valuable time seeking out thisinformation, much of which you'd possibly nevercome across

Creative Computing will providehours of mind-expanding enter-tainment, even if you don't have acomputer.

Creative Computing carries 10 or 12 pages of gamesand puzzles every issue Most of the puzzles don'tneed a computer or calculator to solve, some doNaturally the 4 or 5 new computer games (in BasicFortran, anc APL) in every issue require access to acomputer

Creative Computing gives youthings to actually do with a com-puter.

Home computer kit. mini, timesharing terminalwhatever your access to computer power. Creativeprovides thoroughly documented programs withcomplete listings and sample runs that you can usewith minimum effort Games, simulations. CAIcomputer art — whether education or recreation isyour bag. you'll find programs which you can use inCreative

A no-compromise policy ofeditorial excellence means everyissue is of value to you.

We firmly intend to be around a long time and webelieve the way to do that is to publish only materialof the very highest quality We believe our readersare among the most astute, intelligent, and activepeople in the world Ycu can't afford to waste timereading imprecise, opinionated, or wordy articlesand you won t find any in Creative

The price is right — only $21 for 3years.

That same S21 will buy you a pair of Star Trek walkletalkies, six direct dialed 10 minute calls betweenNew York and Boston. 3 tankfulls of gas, or 10cocktails at a Hilton hotel Wouldn't you rather have18 issues of Creative Computing each containingover 85 pages of solid editorial material (includingadvertising over 100 pages per issue) Count theeditorial pages in any other hobbyist or specialinterest magazine and compare it to Creative Anyother l year subscription S8 Lifetime S300.

NO RISK GUARANTEE

You may cancel your subscription at any time forany reason and we will refund the balance without

q"es"°n David H Ahl. Publisher

FOR FASTER RESPONSE

Yo'j can phone your subscription orders to us at(201; 366-5617 Our lines are open from 9 am to4:30pm EST

SUBSCRIPTION ORDER FORM

Type

individual

Institutions

Term

l-Yeai

3-Year

Lifetime

1-Year

3-Yeai

USA

□ S 8:' 21D 300

□ 15

□ 40

Foreign

l; S 10D 27

i! 4001540

D

New Renewal

□ Cash check or M O enclosedBankAmencard Card No.

l Master Charge

Expiration date

□ Please bill me (S1 00 billing fee will be added)Name

Addiess .City

Stale .

.Zip

Send to Creative Computing. Department B

P O Box 789-M Mornstown, NJ 07960

mm

mmm3

Deal

yourself in

Special group rates for\clubs and

organizations traveling frorfivthe West^

Coast and Mid-America contact^ \ \

7 Seas Travel

17220 S. Norwalk Blvd

Cerritos CA 90701

Dawn Corrigan

213-924-8383

Atlantic City, N.J.August 27th-28th

What it's all about!

Software Development

Micro Computers

Hardware Development

Disc Memories

Computer Comparisons

Interfacing

Program Implementation

AMSAT

Computerized Music

Video Terminals

Kit Construction

Printers

Computer Games

Digital Tapes

• Seminars and Technical talks by leading electronic equipment manufacturers

• Major Exhibits from all over the country

• Demonstrations in many areas including Home and Personal Computing

• Door Prizes, Free Literature and Free Mementos

• All this plus Sun and Surf - Fun and Excitement - Relaxation and Leisure

Personal

|^ Computing

Write for FREE TRIP-KIT to PERSONAL COMPUTING 77,Rt 1, Box 242, Mays Landing, New Jersey 08330

77

Consumer Trade Fair

EXHIBITION BOOTHS STILL AVAILABLE - CALL (609) 653-1188

New kidon the

block!

But watch out

he means

business

PERSONALCOMPUTING EXPO

COMES TO NEW YORK FOR BIG BUSINESS

It's a brand new show in the world's biggest economic centerspecifically for manufacturers and buyers who are into personalcomputing. For the first time, this booming field will have a NewYork Coliseum showcase in the major population center in theeast. It is planned as the largest public show of its type in the worldthat will attract enthusiastic buyers from a multi-state area.

WHY NEW YORK?

New York is the economic nerve center of the world. It also isthe world's communications focal point, the one place that will putpersonal computing in a significant spotlight. New York is sur-rounded in depth by people who work in the computer field, bycomputer learning centers, universities, personal computingclubs, and thousands of others whose lives are affected bycomputers.

From this vast potential, Personal Computing Expo will drawthe hard-core hobbyist, the interested student, and, because of ahighly-publicized program of introductory seminars, those whoare attracted and fascinated by computing but have not had expo-sure to the ways and means of becoming personally involved.

SHOW MANAGEMENT

Personal Computing Expo is being produced by H. A. Bruno &Associates, Inc., a firm in the exposition and promotion fieldssince 1923. Highly skilled in the production and promotion ofconsumer and trade shows, the company currently promotes theAmerican Energy Expo, the National Boat Show, Auto Expo/New York. Promotion assistance also is currently rendered to theNational Computer Conference and the Triennial IFIPS Congressin Toronto.

The show producer has promoted successful shows in the NewYork Coliseum every year since the building opened in 1957.Staff personnel are thoroughly familiar with the building, itsservices, management and labor.

EXCITING SEMINARS FROM "BYTE"MAGAZINE

Personal Computing Expo is endorsed by "Byte" magazine,whose staff is developing an exciting series of seminars andlectures for the exposition.

Visitors to the show will be able to attend these meetings free ofcharge. They will hear from lecturers such as Louis E. Frenzeland Carl L. Holder. More importantly, visitors will be able toattend meetings aimed at their proficiency levels, from beginnerthrough intermediate and advanced personal computing.

FOR DETAILED INFORMATION CONTACT:

RALPH IANUZZI, Show ManagerHA. BRUNO & ASSOCIATES, INC.78 E. 56th StreetNew York, N.Y 10022(212) 753-4920

PCE

Endorsed by BYTE Magazine

OCTOBER 28, 29, 30, 1977PERSONAL COMPUTING EXPO • NEW YORK COLISEUM

John F HerbsterHerbster Scientific3233 Mangum Rd, 100Houston TX 77092

TechnicalFopum

Improving Quadratic Rehash

"Making Hash With Tables" by TerryDollhoff/fiVTE, January 7977, page 18] is agood introduction to hash tables. However,quadratic methods for collision avoidance donot have to be complicated or suffer from"half table search." If the table length is apower of 2 and the quadratic increment is 3as in the following simple and fast algorithm,then none of the table will be excluded fromthe search.

I have been using this scheme since about1970 but have never seen it reported in theliterature. Your readers may write to mefor a copy of the proof that it works."

A Quadratic Hash Table

The following algorithm assumes thatthe table length is a power of 2, the tablewords were initialized to VIRGIN, andMASK has a value equal to the table lengthminus 1.

1. Set DEL to 0.

2. Set I to hash code of KEY.

3. LET l = l.AND.MASK (eg: AND Iwith MASK).

4. IF TABLE (l)=VIRGIN then go toNOTFOUND. (Note that TABLE(I)refers to the contents of locationTABLE+I).

5. If TABLE(I)=KEY then go toFOUND.

6. Let DEL=(DEL+3).AND.MASK.

7. If DEL=0 then go to FULL. (Notethat DEL gets back to 0 only afterthe whole table has been searched.)

8. Let (l = l+DEL).AND.MASK.

9. Go to step 4.

On return to the user's program via theNOTFOUND, or FOUND exits, the index, I,will point to the spot for a new table entryor the found entry respectively. The FULLreturn means the KEY was not found andthat the table is full. Note that the valueVIRGIN may not equal any possible valueof KEY.

Yr-

CONFERENCE

MM

of vital interest to all microcomputer enthusiasts:

Build Your Own Computer

a

Saturday, May 14,1977, at the Institution of Electrical Engineers,Savoy Place, London WC2, England. (10;00a.m. - 5:00 p.m.)

j

The following specialists will speak on a wide range ofmicrocomputer related subjects:

^

Conference Chairman: Dr. Chris Evans, Psycholo-gist and computer scientist, author and radio/TVbroadcaster. A specialist in the application of microe-lectronic theory to the human environment, Dr. Evans'topic will be in the area of forecasting the social andhuman impact of microcomputers in the home.

Keynote Speaker: Manfred Peschke, Publisher ofBYTE Magazine. His subject, "Personal Computers inthe United States", will cover computer programming,machine language, and the hardware aspect as itrelates to personal computer enthusiasts.

For full details, including hotel reservations, contact:

Roger Barnes, Online Conferences Ltd.

Cleveland Road, Uxbridge, UB8 2DD

England

Phone: (895) 39262

Dr. Martin Healey of University College, Cardiff,Wales, will give an introductory tutorial outliningterminology and digital electronics followed by a talkon how to build your own computer.

Guy Kewney, computer correspondent forElectronics Weekly, is a keen hobbyist who willdiscuss various kits.

Other speakers: RichardJan Pringle - John McNulty

Monkhouse

IAa

Conference attendance fee:£ 8 - in advance

£ 9-atdoor

=S

JJL

142

What's

New?

Keep Track of Real Time Now

(What Other Kind of Time is There?)

TED, POB 4122, Madison VVI 5371 I,has announced this lillle real time clockaccessory for your personal computer, asmall board with a National Semicon-ductor MM5318N clock chip, interfacedrivers and a trimmable crystal oscilla-tor. The board requires 4 parallel inputlines and 3 parallel output lines (TTLcompatible) and power supplies of +5 Vand +1 2 V. Using pushbuttons, you canset the time and forget about it, es-pecially if you use a battery backup tokeep the oscillator and clock chip run-ning through power failures.

Cambion Patch Cords . . . and Things

Cambion, 445 Concord Av, Cam-bridge MA 02138, has sent us a flier onwhat will probably be a most useful testand prototyping gadget for those whouse wirewrap sockets. The product is aset of different length patch cords whichhave female connectors at each end, forsliding over wirewrap posts which are0.025 inch (0.064 cm) square. These areideal for experimental last minutepatches in complicated wirewrap panels,and will also prove useful for permanentjumpered options which can be quicklychanged. They can only be used forsingle link jumpers, since no provisionhas been made for multiple terminalbuses. They are part of the Cambion XQline of packaged parts for retail sale, aline which computer stores should find agood drawing card. The list price for atypical package of five jumpers with 2, 4or 6 inch (5, 10 or 15 cm) lengths is$8.15. Other lengths and assortmentpackages are also available. For moreinformation on this and other productsin the XQ line, write to Cambion and askfor XQ products pamphlet and the latestprice list. The XQ line ranges fromprecut and stripped wirewrap wire($5.58 per I 00 3 inch [7.5 cm] lengths)to manual wirewrap tool ($3.50) toelectronic terminals, to an experi-

This clock is sold assembled andtested, and comes with a manual andinterface connector. The cost is $39.95plus $.75 postage. When you hook it upto a single 8 bit PIA parallel port (orequivalent) you'll be able to keep trackof the lime of day for household auto-mation, use it as a timer in gameapplications, or even implement suchexotic software as a personal eventscalendar with automatic reminders."

menter's thermoelectric module($19.95) which acts as a solid state heatpump which can be used to cool every-thing from beverages or transistorsdepending on how you apply it."

A New Desk Top Video Computer

Robert Boyer, who is starting a firmcalled Computer Data Systems ofNewark DE, sends this picture of a newproduct they plan to market in the nearfuture. The specifications according tothe press release accompanying this pic-ture include:

• 9 inch high resolution monitor

• 63 key ASCII encoded keyboard

• video display board providing1 6 lines of 32 characters

• I 0 A power supply

• 8080 processor with ROM op-erating system, real time clock,cassette interface

• AlLair compatible bus with 10sockets

• Commercial CRT cabinet withsmoke grey screen and coolingfan.

The press release describes this prod-

SWTP 6800 OWNERS-WE HAVE A CASSETTE I/O FOR YOU!

The CIS-30+ allows you to record and playback data using anordinary cassette recorder at 30, 60 or 120 Bytes/Sec! No Hassle!Your terminal connects to the CIS-30+ which plugs into either theControl (MP-C) or Serial (MP-S) Interface of your SWTP 6800Computer. The CIS-30+ uses the self clocking 'Kansas City'/BiphaseStandard. The CIS-30+ is the FASTEST, MOST RELIABLE CAS-SETTE I/O you can buy for your SWTP 6800 Computer.

PerCom has a Cassette I/O for your computer!Call or Write for complete specifications

Kit - $69.95*

Assembled - $89.95*

(manual included)

* plus 5% f/shipping

PerCom Data Co.

P.O. Box 40598 • Garland, Texas 75042 • (214) 276-1968PerCom — 'peripherals for personal computing'

BAW»*MiRIC>flCTEXAS RESIDENTS ADD 5% SALES TAX

143

uct as "The Versatile CRT," which willbe available in kit form at $995.95 plusshipping. Availability is projected forearly 1977. For more information, con-tact Robert Boyer at Computer DataSystems, English Village Apts, AtramHall #3, Newark DE 197 I l.«

Why Is This Fellow Smiling?

Because he's Pete Roberts, owner ofComputer Kits Inc, the MITS distribu-torship in Berkeley CA, and he's cele-brating the start of his second year inbusiness according to the press releaseaccompanying this picture. He's doingwell enough to be contemplating theopening of three additional stores in theSan Francisco Bay Area to complementhis present store in Berkeley at 1044University Av.»

A Southwest Technical ProductsCoverup, Revealed . . .

Parsec Electronics is now marketingan enclosure kit for the SWTPCCT-1024Terminal System. A two enclosure de-sign is used to give the terminal suitableprotection while retaining the flexibilityof a movable keyboard for the user. Thetwo cases are formed from strong, re-silient ABS plastic and are "color coordi-nated" to blend in with Ihe SVVTPC6800 computer system. The keyboard

enclosure has the cutout and mountingpads for the KBD-5 keyboard and a fullyenclosed bottom. The main case featuresmounting pads for the CT-1024 mainboard, the GT-61 graphics board, theAC-30 cassette interface board and roomfor their power supplies. The kil includesmounting hardware for all circuit boards,a healsink for the power supplies andrubber feet for both enclosures. Formore information contact Parsec at POBA82327, San Diego CA 92138."

BYTE'S FOREIGN SUBSCRIPTIONS

BYTE has more foreign readers than ever before. The magazine has almost doubled in weight, and is expected toincrease further. Also, postal rates have gone up. In view of these increases we need to raise our foreign subscriptionrates effective May 1, 1977:

CANADA and MEXICO: For one, two, or three year subscriptions, add $5.50 per year to the US subscription

rates.

WESTERN EUROPE: For a one year subscription only, add $13 to the US subscription rate (total $25). The

magazines will be shipped by air. Present subscribers in western Europe who wish to convert their subscription

to air delivery, please contact the publisher.

OTHER FOREIGN COUNTRIES: For a one year subscription only, add $13 to the US subscription rate (total

$25). The magazines will be shipped by surface mail from selected distribution centers in the US or abroad.

For additional air rates, please inquire.

We hope that our new distribution routes will expedite the delivery of BYTE. Please let us know of any excessive delaysin the delivery of your issue. Thank you.

BYTE SubscriptionsPO Box 361Arlington MA 02174USA (617) 646-4329

Please remit subscriptionsin U.S. funds. Thank you.

144

Solution and Comments to "An 8080 Bug in the Stack," April

A programmer's reaction is to first checkout SVREG and GTREG to see if the stackis being used improperly or to see if thePUSHs and POPs somehow disturb the orderof saving and restoring registers. This is agood exercise in the use of the 8080 stackinstructions, but reveals nothing.

Almost instinctively, the next trial fix isto change the code to

SUBRX: CALL

CALLRET

SVREG ;SAVEALL

GTREG ;RESTORE ALL AND RETURN

1977 BYTE, page 161:

Now, the two subroutines perform cor-rectly, but it is not clear why until the pro-grammer really digs into the stack manipula-tions. When enough digging is done, it finallyturns out that GTREG expects a returnaddress at the top of the stack, but there isnone if JMP GTREG is used. Instead, thetop of the stack contains the saved contentsof double register D,E and the desired returnaddress is actually buried down in the stackand will not be available until the stackpointer is incremented 8 times (by 4 POPs).

One could also fix GTREG so that it isalways entered with a JMP (and never aCALL), but the way it was originally coded,GTREG must always be entered with aCALL."

Blabberwacky: Answer to Bar Code Puzzle

Here is the answer to the bar code puzzleposed on page 130 of the March 1977 issueof BYTE. We'll have a report on the contestwinner prepared in time for the July issue,after the deadline of March 31 has passed.As this note is written, we have receivedword of two promising designs for readers,one prepared by an associate of ChuckAdams at Texas A&M University, andanother prepared by Fred Merkowitz, whowrote an article on the subject of signalprocessing circuits in the December 1976BYTE [page 77].

'Twas brilliant and the slimy toadsDid go and gander in the wave:All misty were the bluish groves.And the mole runs outraged.

"Beware the Blabberwack, my son!The words that bite, the barbs that catch!Beware the mynah bird, and shunThe frivolous Bendersnitch!"

He took his vicious words in hand:Long time the slanderous foe he soughtSo remained he by the tilting tree,And stood awhile in thought.

And, as in malign thought he stood,The Blabberwack, with eyes of flame,Came whistling through the stately wood,And bluffed as it came!

One, two!, One, two! And through and throughThe vicious blade went crushing-crash!He left it dead, and with its headHe went galloping back.

"And hast thou slain the Blabberwack?Come to my arms, my bouncing boy!O fabulous day! Hoorah! Hooray!"He chortled in his joy.

'Twas brilliant and the slimy toadsDid go and gander in the wave:All misty were the bluish groves.And the mole runs outraged.■

"We may have the surplus

electronics

you need!"

Terminal/KeyboardWith SchematicsS250.00

• CRT Terminals•Assemblies

Tape Drives S800.00

• Peripherals

• Components

Keyboards S40.00 to S60.00(ASCII Encoded)

Equipment Cabinets S45.00 to S60.00(19" With Fan)

Send for a free catalog or callBill Blaney, toll free 800 258-1036

in NH 603-885-3705

iwmi Come to our showroom

VJUI Lav/UL ELECTFUmCSjnC.

10 Flagstone Drive, Hudson, New Hampshire 03051

145

Bock Reviews

Editor's Note: A home-brew content addressableparallel processor designwould make an excellentexperimental topic for anarticle or two (or n), andtutorials on the subjectwould provide excellentmaterials for B YTE,

Content Addressable Parallel Processors byCaxton C Foster, Van Nostrand Rein hold,New York, 7976, 233pages, $11.95.

Do you know anybody named Frank?

— Oh, sure, Frank Smith, you know, . . .

— Stop. How did you know? Let's try afew models:

1. Consider everybody you know, stop-ping when you hit Frank.

2. Perform a binary search on youracquaintances, whom you keep in mind,sorted by first name: perhaps you hit Nancy,then George, then David, Fred, Frank.

3. Mentally compute a hash address on"Frank," plucking him from a linked colli-sion overflow list in an average of 1.37probes.

If you're a computer, that's how youknow, or by some similar method, whetheryou're looking for names, syntactic tokens,transaction numbers, or whatever; that is,you do unless you are a CAPP (see title).

I had heard of and talked about parallelprocessing but had always thought before interms of multiple processors locked intosome sophisticated intercommunicationscheme requiring finicky timed programmingwith all the trimmings. The main revelationin Foster is the simplicity with which truecontent addressability and parallel operationmay be obtained. My main trouble, if I cancall it that, is that although the concepts andtechniques have been around for 20 years(see the preface), CAPPs remain obscure andnot in general use.

Take an ordinary word of memory; add abit to the end; add a couple of gates to eachbit of the word to turn on and off the newbit by comparing the present values of thebits to the information on some data bus.Furthermore, connect the new bit back intothe write enable circuitry, so it can controlthe writing into that word. Now throw away

the address circuitry; you don't need it anymore. Your word can now be addressed byits contents.

To find Frank in your table, put him onthe data bus in the proper field of the wordand activate the compare lines. Bingol Oneinstruction table search. (CAPPs tend tohave long words for obvious reasons.)

Select your favorite algorithm. Replacethe branches with instructions that select theproper words in memory, and in the time ittakes to perform each step in sequence, youcan execute the algorithm on every word ofmemory simultaneously. That's what theparallel processing part of the name means.

If you are busy laughing at all the holes inthis architecture and explanation, read thebook; I gave only the most cursory ofexplanations. The CAPP as hardware has, itseems to me, the same advantages that APLhas as a language: the ability to perform insingle operations what would otherwise bemachine time consuming loops, or program-mer time consuming complex algorithms orklugey hacks.

Just to get in some actual criticism, Ifinished chapter 8, on STARAN (the onlycommercially available CAPP), still waitingfor the other shoe to drop. It seemed tocontain all details and no gestalt descriptionsof the machine instructions but no sampleprograms (exception: the add fields instruc-tion's inner loop), nothing about who hasthe things, what they do with them, etc.This is just carping, however; the book is ingeneral well written and contains material ofinterest on every level from hardwarethrough analysis of algorithms to expositionson applications. I recommend you buy, beg,borrow or steal the volume and devour it atyour earliest opportunity.

J Storrs Hall

16 Easton Av

New Brunswick NJ 08901 ■

146

32 K

PERSONAL

MINICOMPUTER

SYSTEMS.

32 KCPU,Two CRT's,And TwoFloppy DiskDrives With262 K BytesEach.

For Details:ABBOTT COMPUTER CO.

57 Gregory StreetMarblehead, MA 01945617-631-8903

8080 Interactive DEBUG

NOW AVAILABLE: A real-time pro-

Sam debugger for all 8080 processors,ebug your code in one-tenth the timeit takes by hand. This is not a simulatorbut a real-time programming aid thatuntil now was only available on mini &macro computers. And it FITS IN 5K!

FEATURES:

*Six I/O modes-Mnemonic, single &double byte numeric, ascii, or dis-placed mnemonic & numeric.

*Four user-defined breakpoints.

*Relocatable to anywhere in memory.

*User-controlled number base—binary,octal, hex; any radix from 2 to 36.

*Commands for displaying & modify-ing all registers-including PSW & SP.

*Search command with masking.

*Block memory move & fill.

*On-line calculator/expression eval'.

*Displacement register for examingrelocatable code.

DEBUG 8080

To Order:

(1) Specify: CUTS cassette $30

or Paper Tape $40

or Manual Alonef $10

or Descriptive brochure $ 1

(2) Your hardware: Altair, Imsai, Sol,...

(3) Send to: - ^^ Timeshare

P.O.Box 2298Berkeley, CA 94702

f refundable on purchase of program

$ r>99

140

NOWHEARTHIS!!

ALPHA DIGITAL SYSTEMS

SELLS IMSAI KITS AND TOTAI INTEGRATED SYSTEMS ASSEMBLEDCHECKED-OUT. AND WARRANTED AT KITPRICES.

TYPICAL SYSTEM» ISffiAI 8080 Computer

* 22 Slot Mother Board

* All Connectors» -IK RAM

* MI° m

*:<CableA .,

* 1 Cable M J.,

* Assembled System Total Slffli-

ALPHA ISPECIAL DOS SYSTEM DEAL (includes!

* IMSAI 8080 Computer

* 22 Slot Mother Bd. with Conn' 16 K RAM (4 4K Boards!

* 90 K Disk (with Controller!

* DECwriter typewriter 80 cps

* DOS-BASIC SoftwareAssembled System Total $8995.

iLess DECwriter) $2495.

Select any kit or system of kits from the IMSAIprice list, order from us and receive theassembled unit for the same price. If you don'thave a price list, drop us a line and we will sendyou one. Terms: Cash with Order ■ Prices in-clude freight. ( NC. Residents Add 4% Sales Tax )

How can ALPHA DIGITAL SYSTEMS do allthis? Its simple. ALPHA DIGITAL WANTS TOBE YOUR COMPUTER COMPANY.

ADC ALPHA DIGITAL SYSTEMS*""'* RT.4BOX171A

BOONE, NC. 28607

(704) 264-7946

Spring into Seasonwith a BYTE T-shirt

At lastl No more wardrobe crises! BYTE T-shirts are here! Now youhave the perfect garb for computer club meetings, Altair Conven-tions, playing Shooting Stars and computer chess. (A pair oftrousers from your own closet is suggested as an addition to theBYTE T-shirt. BITS can't do everything for you.)

BYTE T-shirts are of top quality 100% cotton or cotton-polyester.The original design, by artist Judy Lee Rehling, is silk screened inred on white shirts with blue trim on collars and sleeves, or on blueheather shirts.

The $5.50 price includes postage and handling.

r

Send to:

In unusual cases, processing may exceed 30 days.

BITS, Inc.70 Main St.Peterborough l\IH 03458

Please send me

-extra large.large.medium.small

Total enclosed $

Bill MasterCharge No

Bill BankAmericard No..Name

Address.City

blue heather

white with blue trim and

red letters

T-shirts @ $5.50 each (includespostage and handling)

Exp. Date

Exp. Date

_State_

^Zip-

Signature

All orders must be prepaid

Prices shown are subject to change without notice.

Ask BYTE

CAN I CONVERT PROGRAMS?

I am 13 years old and my dad recentlypurchased a KIM-1 microprocessor. I haveseen a lol of BASIC programs and I wish toknow if there is any way to convert theseprograms to assembly language or, say, MOSTechnology machine code.

Kevin Schnitzius

308 Stockley St

Rehoboth Beach DE 19971

Yes, [here is. It involves silting downwith the program, figuring out what it does,then doing the same things using the ma-chine or assembly language. In many cases,the BASIC version of a program will take upmuch more memory than its machine lan-guage equivalent, hut even so for numerousgames you'll want to have a fair amount ofmemory in the system. The conversion couldbe compiled automatically on a large ma-chine with an appropriate translator programif it were available, but you 'II probably haveto do it the hard way by hund.'

SYSTEMS INFORMATION NEEDED

We need help, more specifically, aneducation! We presently own a PDP-8-E, with20 K, dual DEC tapes and four Teletypes.We need to find a source of clearly writtendirections or information that will allow usto do the following without hiring aspecialist:

1. Choose the right modems which willallow us to move a Teletype aroundthe school and use the school's 2 digitphones (or any phone system).

2. Hook up the modems correctly.

3. Decide whether we can interface aninexpensive floppy disk to the system,how to do it, and what parameters andramifications we must face.

4. Decide whether we can interface otherinexpensive peripherals shown inBYTE to our system.

5. Write handlers for peripherals.

There seems to be too much expense in-volved if we go. through DEC. We have the

The Great

International

Math On Keys

Book

mo meets

From Texas Instruments

Do you need a numerical algorithm for calculating exchangerates in a hotel on a foreign trip? Or figuring thosemysterious "points" when facing the sanctimonious charismaof a banker at mortgage arrangement time? This book is acompendium of simple explanations and step by stepprocedures for accomplishing numerical solutions tonumerous commonly encountered situations in daily life.Each entry is characterized by a statement of the problem,including the elements of theory required, and the keystrokesneeded to solve the problem on an algebraic entry calculator.This is an invaluable sourcebook of information for theperson who is inclined to manipulate numbers. $4.95, plus 35cents postage.

Send now to:

BITS, Inc.

70 Main Street

Peterborough N H 03458

Master Charge andBankAmericard Welcome.

Please allow six weeks for delivery.

programming ability and the mechanicalability, but it ends there.

We would appreciate any help you couldgive us. Thanks for your cooperation.

Richard A Brown

Instructional Computing Director

Minnechaug Regional High School

621 Main St

Wilbraham MA 01095

Would any reader be able to help outRichard in his quest for information? Some-one with familiarity with DEC equipmentand intercom style telephone systems wouldbe best qualified. ■

LINEAR EQUATIONS

In my business I use a commercial time-sharing system to solve a system of 1000nonlinear simultaneous order 36 differenceequations (but with an average of only tenterms in each equation). This requires about30 seconds in a core memory of only 600 Kbytes. Since reading your magazine I havewondered whether this problem could besolved with any of the larger home-sizedcomputers, say 64 K bytes core, somefloppy disks and cassettes, allowing asmuch as 24 hours continuous running forthe job. Would you have any idea whetherthis is possible, assuming all the softwarewere available? (I believe this would requirea kind of software not yet marketed formicrocomputers, something similar to thevirtual memory timesharing system monitorswhich keep most of a job's data on high-speed disks while feeding portions of itinto core and back to disk many times inthe course of the run.)

George Lyons

280 Henderson St

jersey City NJ 07302

Yes, it sounds possible, provided youalways treat subsets of the big array at anygiven time. However, you must note thatseveral large computer operating systemsfeatures may have to be explicitly coded inyour BASIC application program on thetypical small computer. The problem will bequite solvable given a computer with anextended BASIC interpreter and a floppydisk for intermediate storage. Where youused a 600 K region of memory for largearrray storage in the large system case, inthe small system case you incorporateexplicit calls to the disk operating systemto roll data in and out of memory buffers asneeded when referencing subsets of the array.The question of how long it will take de-pends upon your programming strategy,the characteristics of the floating pointpackage in the BASIC interpreter, and thedesign of the floppy disk interface. (Doesit use interrupts and DMA, or does it requirededication of the processor to 10 manage-ment during 10?)

Authors Take Note: Techniques of handlingsuch large arrays in BA SIC with disk facilitieswould make an excellent topic for severalarticles. ■

To Dean Blondefield:

I read in the January issue of BYTE inthe "Ask BYTE" column that you are inter-

estcd in books about robots. I just finishedreading a book entitled Build Your OwnWorking Robot by David L Heiserman,pub-lished by Tab books (Blue Ridge SummitPA 17214). Although I was able to get thecopy I read from the local library, it appearsthat the book can be ordered directly fromthe publisher. The price on the book was$5.95. Ill's also available from BITS./

This is a "how to" book complete withdetailed schematics and parts lists. Eachchapter is a single project which adds an-other feature to an ever growing robot. Thefinal project, which the author dubsBUSTIER III, can follow a predeterminedpath laid out with masking tape or "wander"about "exploring" the environment. It alsohas an override "hunger" control whichcauses it to seek out its "nest" where it willstay until its batteries are recharged. Once ithas "filled itself" it will resume exploring.

Please note that I have not said anythingabout sight, hearing, arms, legs or humanoidcharacteristics. That is not what is meant by"robot" in this book. What is meant is adevice which consists of complex digitallogic (all the circuits are TTL) controlling asimple machine. However, all the basic fea-tures of any robot arc embodied. "Self"control, "self" protection, an ability to sensethe environment, and even a primitive "cry"of "panic" or "hunger" are "programmed"into BUSTER's circuits The underlyingprinciples of control and feedback arethoughtfully applied. The book appears tobe a first. And as such it is an excellentbook.

We need experienced people with mini or micro pro-gramming experience. You must have experience ineither assembly, fortran or basic plus. Experience withRSX-11, RSTS or an other realtime operating systema definite plus (Decnet or Arpanet).

Up to S19 K

APPLICATIONS PROG RAMMERS

COBOL in an IBM OS or DOS environment will openthe door to this prestigious firm in greater Boston.Four day work week and tremendous benefits are partof this outstanding opportunity.

Up to S18 K

SYSTEMS PROGRAMMERS (Large Scale)

Experience in communications, sysgens, OS internalson IBM 370 or PDP 10's are best. Challenging oppor-tunities exist from Massachusetts to California.Call or send resume to: UptoS19K

I or send resume to: upto=>rMi\

digital arts group

^fl j\ Engineering & Software Personnel ConsultantsNine Bedford StreetBurlington, Massachusetts 01803(617)273-2780

Our staff will also be available for consultation Monday

and Wednesday evenings until 8 p.m.

COMPUTERFEST

The Second Annual Midwestern Regional Computer Conference

* Major Attractions *

Flea MarketSeminars

Manufacturers' exhibitsTechnical Sessions

V.

Court Hotel, Cleveland Ohio

June 10, 11, 12

For Additional Information:

Gary Coleman

Midwestern Affiliation of Computer Clubs

PO Box 83

Cleveland OH 44141

P.S. To make life easier we are charteringa jet to Dallas the next weekend.

r

149

/£-~-\\ SALES. EXECUTIVE OFFICES A WAREHOUSE

^/S/A_U fffSCO ELECTRONICS Airport In

dustrial Park / />

irporl and Central Hwys.

. >- flirf.o Zlccttic Sirvict Co. of Pa.

Pcnnsauken. New Jersev 08110

~%dd^

(215) 925-6900 ■

(609) 662-4000

MAIL ORDER SOURCE FOR MOTOROLA

MPU PARTS

PLASTIC MPU FAMILY PARTS

MC6800P 8 Bit MPU

21.95

MC6820P PIA

10.00

MC6850P ACIA

12.00

MC6852P SSDA

17.00

MC6860P Modem

15.00

MC6810AP 128 x 8 RAM

5.00

MC6880P Data Bus Extender

3.60

MC6828P Priority Interrupt Controller

9.60

MC6885P Address Bus Extender

1.95

MEK6800D2 Microcomputer Design

Kit

235.00

Machine language programs can

be entered

thru the

system Keyboard or via a built

in Audio

Cassette

"Kansas City" interface systerr

Hexidecmil LED

displays are provided tor monitoring data an

i address

information

MEC68MIN2 Minibug 2 ROM

75.00

MEC68MIN21 Minibug 2 Listing

25.00

Check our January Ad for additions

MPU System Parts

DATA BOOKS

Linear

3.30

McMos

2.75

Semicondutor Selector

2.20

Bipolar Digital Logic Guide

2.20

MPU LITERATURE

Programming Manual

10.00

Applications Manual

25.00

System Design Data

2.20

Exorciser User Guide

5.50

Data Sheets

.50 ea.

$10.00 minimum order, $2.00 postage & handl

ng 5%

Tax NJ residents. Delivery: stock

to 4 wks.

Money

Order or Cashiers Check only.

TIRED OF THE PARTS ORDERINC

PROBLEM ....

COME TO R E S C O FOR YOUR

M6800 MPU SYSTEM.

21 START-AT-HOMECOMPUTER BUSINESSES

in the shoestring, start-at-home

computer business handbook

CONSULTING ^PROGRAMMING "SOFTWARE PACKAGES »C0MFREELANCE WRITING •SEM INARS •TAPE/D I SC CLEANINGFIELD SERVI CE •SYSTEMS H 0U S E S • L E AS I NG »S U PP L I E SPUBLISHING «TIME BR0KERS •HARDWARE DISTRIBUTORSSALES AGENCIES ^HEADHUNTING ^TEMPORARY SERVICESUSED COMPUTERS »F INDER1 S FEES«SCRAP SUPPLIES 5COMPONENTS «EDP PRODUCTS AND SERVICES FOR HOME

THE EHOSBTSiKB.STARTAT MDME.

computerbusinesshandbook

Plus - hundreds of Ideas onmoonlighting, going full-time,image building, revenue building,bidding, contracts, marketing,professionalism and much more.No career planning tool like Itever published. Order yours rightnow and if you're not completelysatisfied, return it within thirtydays for a full immediate refund.

• 8i X II r ingbound »1 1 3

• $12.00

DRTRSERRCH

incorporated

730 WAUKEGAN ROAD • SUITE 108DEERFIELD. ILLINOIS 60015

Rush copies of "The Shoestring Start-At-Home

Computer Businesses Handbook" right away.

Name/Compa ny

Add res s

City/State/Zi p

LjCheck EnclosedLjBankamericardLZ]Mastercharge

One word of reservation: I did findfrequent minor errors in the diagrams (un-labeled or mislabeled parts and a few blankentries in some tables), but these errors wereall correctable by the reader.

Terry E Weymouth

4702 Beau Bien Ln E

Lisle IL 60532"

ALLEGED MORAL VOID? HARDLY

After settling down and reading theJanuary 1977 "Ask BYTE" columnI page 140], I found myself a bit dis-mayed. As a graduate electrical engineer-ing student, I found your remarks to beaccurate and succinct. Basically, I'mconcerned about the glaring lack ofethical considerations on Blondefield'sand your part.

It has been an unfortunate engineer-ing tradition to say, "If it can be done,let's do it." No questions asked. The bigquestion in engineering (and robotismand artificial intelligence in particular) isusually ignored: "Should we build this?"or "Should computers be given thesetasks?" In the case of robots, one shouldask what fields of human endeavorwould the artificial intelligence of therobot be applied to. Would the robotwhich is mopping the floor also listen toyour problems? (Many people hope so.)The idea here is not to come up with anengineering answer, but to ask which ofthe possible applications would be detri-mental to man. In my opinion, many ofthe future applications of computers, asenvisioned by engineers, are unethical.For instance, Blondefield's naive robotimpossible dream seems to be the tip ofan ethical void.

Computers are being plugged intoapplications left and right without anounce of thought about their adverseimpact on society. Examples are "acomputer in every home," communityinformation centers, and computerpsychiatric counseling. The applicationof computers affects our view of theworld and our fellow man. Their ulti-mate usage may turn out to be quite aninsult. A person who says "I wantrobots" should look a little deeper andface the humanistic and ethicalarguments.

Robert Garner

1795 Stanford Av

Menlo Park CA 94025

Unethical? Detrimental? By whatstandard do you make your evaluations?By any truly human standard of value,computers and robots are highly de-sirable technology: the former for theirautomation of mental drudgery, the lat-ter for their automation of physicaldrudgery. Human beings are the measureof morality, not the current state ofsocial interaction and technology —which can always be improved. A viewof morality which precludes improve-ment in the quality of life of humanbeings is a monster which should havebeen left in the dark ages. ■

150

THECOMPUTER CORNER

Lower Hudson ValleySouthern Connecticut

•IMSAI 8080•POLY-88•Teletype supplies•Full line of magazines

• Processor Tech•Computer Book Service•Magnetic tapes & disks•Brain Games & Puzzles

THE COMPUTER CORNER

White Plains Mall

200 Hamilton Avenue

White Plains, N.Y. 10601

Tel: (914) 949-DATA

Hours:

10-6 Daily & Saturday

10-9 Thursday

PHOENIXBits & Bytes

COMPUTER SHOP

6819-C N. 21st Ave.

Phoenix, Az. 85015

(602) 242-2507

•VECTOR-1 Z-80 Computers

• EPA 6800 Computers

•ACT-1 Terminals

•Full line of magazines & books.

•Z-80 for Vector/Altair/IMSAI

•Tarbell cassette board

•Sanyo 9" monitors

•EPROM burner boards

•8K RAM

•16K RAM

•Video boards 1 6 X 64

PACKAGES - SPECIAL LOW PRICES

* Z-80 with EPROM & 17K RAM is

only $999 (kits)

* 6800 with 8K RAM all I/O

completely assembled $1199

jUC Affordable jJC

YOU'VE SEEN THIS PRINTERATTWICETHE PRICE . . .

NOW ONLY $296.00*

NEW! NOT USED! COMPLETE!

EXPANDOR PRINTER

• Operates at 10 CPS

• Prints 80 positions wide-10 CPI

• Pin feed platen included

• 8 Bit parallel interface included

• 64 Character ASCII code set

P.S. It's compatible with the

PortaCom.)

Cover optional at $29.50

* Pa. residents add 6% sales tax

CHECK...MONEY ORDER...BANK

AMERICARD...MASTERCHARGE

EXPANDOR INCORPORATED

Dept. 111, 612 Beatty Road,

Monroeville, Pa. 15146Telephone: (412) 3730300

7338 Baltimore Ave. Suite 300

College Park, Maryland 20740

JOINT VENTURE

GROUP OEM BUYS

IMSAI made kits h assembled uniis 1E

TEC-9900-SS-UF, 16 bit TI9900 microP,hardware mull & dtv, bullered bus, 20 rna cinterrupts & sockets

TEC-9900-32KB 32K bytes memory

TEC-9900-PP trowet supply

SPHERE kits b assembled units _

RS 232. 8

. $279.00

3649.00

$129.00

_10% OFF LIST

CROMEMCO k.is ft / 1

SANYO IV Monitors

TDLZPU&Z16K .

SEALS Bk bai backup Mem _PERSCI Dual floppy & mtelligen10/0)

SHUGART MINI f LOPPY

10% OFF LIST

10% OFF LIST

10% OFF LIST

10% OFF LIST

ittoiiei 1*2/0 &

$1395.00

$350.00

AMD FACTORY PRIME 1 ESTED lor MIL SID 883C

91L02 500ns.

91 L02 100ns

Z-80mic:roP

Z-80-CTC

_$1.90_$1.99

_$54.00_$15.00_$17.00

80B0 PPI $10.00

81121 OpDfl $2.50

8228 Clock Dover- $5.50

9555 PPI $9.50

ZTOBEpran

9102500 ns9102400ns

Z-80PIO_

_$59.00

8080SCI

8224 Clock Gen8216,26 Dnvei _

9551 PCI

2102680 ns

S1.85

S1.95

_$15.00_$8.00_$20.00_510.00_$4.75_$2.50

$9.50

51.75

ADM-3K ■ CR-1 & addressabteCursor S925.00IUAXIOM 80 col, ifio char/sue printer, parallel

$665 COhst.serial interface S740 OOhsl 10%

Nat. Multiplex Digital Tape recorders b kits 10%

MSI fioppvsb kits 10%

Pennywhistle modem

Tl ■

ASTRAL 2000 k u

i 700"

iodel 743. our

\MVj I

$825.00

OFF LIST. 10% OFF LIST_10% OFF LIST__5% OFF LIST;i 5% OFF LIST_10".: OFF LIST

Send S2 CO lot newsiettet b listsother chips 2900 seres 4K mems etc6 pin sockei ft cap lor memory chip ?bpavmeni 'or discounts, add 4%. mm 4 00:< shipping ft handl tig, orders bulked lo>■owest discount en OEM G/Oup buys

LONG ISLAND

first: > ^^

OPEN

BYTE

Tues. - Fri.

-44HP

11 to 9 |

onLir

Sat. o0

&

10 to 5 Xtb, e<°

We have . . .

IMSAI 8080

SOL

Byt-8

Processor Tech

SWTP MP68

Interfaces

CROMEMCO

Memory Expansion

TDL

Lear Siegler

Poly-88

Floppies

Cassetts

Dec Writers

KITS and ASSEMBLED

BYTE SHOP EAST, INC.

27-21 Hempstead Turnpike

Levittown, Long Island NY.

(516) 731-8116

Two Blocks East of Wantagh Pkwy.

COMPUTER MART

A NEW YEAR, A NEW LOGO, A NEW STORE ! !

Last year we opened the first computer store on theEast Coast. This year we move out of the HobbyStore and into our new Real Systems Showroom andStore. The largest display of up-and-running com-puter equipment. The same friendly help and advice.Plus-all the bits and pieces you can't find elsewhere!Plain and Fancy Software too!

IMSAI, PROCESSOR TECHNOLOGY, SOUTHWEST TECHNICAL PRODUCTS, DIGITAL GROUP,OSI, VECTOR GRAPHICS, ALPHA MICRO TECH-NOLOGY, MSI, CROMEMCO, COMPUCOLOR,POLYMORPHIC SYSTEMS, SOROC TERMINALS,SEALS, TARBELL, MORROW, TDL, NORTHSTAR, QUAY, APPLE, OLIVER, SMOKE SIGNAL,MULLEN, GBC MONITORS, O.K. MACH. CONT.SPEC. VECTOR, E&L INST, and- COMPUTERMART PRODUCTS. More Coming! !Stan Veit -Storekeeper.

COMPUTER MART OF NEW YORK INC.118 MADISON AVE. (ENTER ON 30th ST.)212-686-7923

PRAMMER

by XYBEK

An extraordinary 2k memory boardfor your Altair-bussed computer

* On-board 1702A PROM programmer

* Space for 1792 bytes of read-only memory (seven

1702A EPROMs)

* 256 bytes of RAM

+ Supplied with one 1702A, pre-programmed withstand-alone programming software — no senseswitches are used

*k Supplied with programming power supply

"fr PRAMMER's own on-board clock makes it compatiblewith almost any Altair-bussed system.

~k All read and write sequences are generated via anon-board micro-programmed state machine, thuseliminating all one-shots.

Send me PRAMMER kits ® $189 ea. (Calif, residents

please add sales tax.) BankAmericard & Master Charge O.K.

-Zip-

Call (408) 296-8188 or write to:

XYBEK • P.O.Box 4925 • Stanford, CA 94305

BYTE's Gits

Photo 1: The NECS meeting beganwith Dave Day, president, attendingto formalities (minimal) then intro-ducing the various speakers.

Unbelievable, but It Worked. . .

Demonstration of the Klugehornat an NECS meeting. . .

Notes by C Helmers

I promised Dave Day (newly electedpresident of NECS) that I'd provide aneat electronic music demonstration atan NECS meeting January 12 1977, to

% ■

N 1 ;

!

T1

1

Photo 2: Gary Sawyer of Motorola gave an inform-ative talk about the new Motorola evlauationboard style computer, which comes in kit formwith a new version of their monitor programs,a Kansas City standard tape interface, and the re-mote control interactive paddle shown. It featurescompatibility with larger Motorola developmentsystems, and the ability to expand memorythrough buffers (not supplied, but wired in viathe PC runs). A prototyping area is also presenton the card.

152

be illustrated using my new multichannelorchestral synthesizer which has onlynow begun to arrive at my lab. But whentime for the meeting began approach-ing, it became apparent that the newsynthesizer was not quite going to beready. What could I do?

Well, two weeks before the event,after having finished the 1200 bps audiointerface described in April BYTE, Idecided to go all out and prepare akluge. The result was the "Klugehorn,"a single channel music synthesizerperipheral output device which wassuccessfully demonstrated at the meetingon January 12 1977 when a hastilyconstructed but quite functional musicinterpreter program played the storedscore of most of Scott Joplin's excellentand well known rag, the "Entertainer."(I stopped hand encoding the musicin the middle of the last part of the pieceat 4:30 AM on the morning of themeeting, so completion was put offuntil after the demo.)

At about 3:30 in the afternoon onthe day of the meeting, I went homefrom the office with my assistantsDan Pagan and Scott Morrow to takethe computer apart, put it in boxes,pack the documentation, and head forBurlington MA and the MITRE Cor-poration cafeteria where meetings areheld. Taking one's processor and systemapart for such purposes is a traumaticexperience. Any one of an unknowablenumber of bugs could incubate andcome to life, interfering with the success-ful reconstruction of a working system.Unbelievably, in complete violation ofMurphy's law, the system went backtogether at the MITRE cafeteria, pluggedinto the wall, and worked withoutmajor hitches. (A false read on the tapeinterface was attributed later to tem-perature sensitivities, since during thetrip to the club meeting it was 0°Fahrenheit and there was ample oppor-tunity for the tape drive and media

Photo 3: Will the stupid program load?

to be cooled into its nonoperable range.)Music is an excellent applicationof the microprocessor, and even giventhe limitations of my quick and ad hocdesign for a synthesizer, the full rangeof intelligent real time control wasdemonstrated. The Klugehorn synthe-sizer peripheral uses a read only memorycontrolled divide chain from high fre-quencies, with 9 bit precision in itsapproximation to the well temperedscale. (A 4 bit code addresses the readonly memory and yields the appropriateone of 12 equally tempered notesof an octave.) This divider output thenenters a series of octave dividers selectedby a 3 bit code. The resulting pitch isthen fed to the shift clock of a 40 bitby 6 bit static shift register, via controllogic which also allows the shift registerto be loaded by a parallel PIA outputport of my computer. The six bits outof the shift register are fed to a 6 bitMC1406 waveform DAC which uses avariable reference voltage created by an8 bit MCI 408 envelope DAC directlyconnected to another 8 bit PIA port.The analog processing logic of opera-tional amplifiers is used to create an ACsignal at the output which has an RMSamplitude set by the envelope and awaveform stored in the shift register.Timing of changes in the envelope ampli-tude are handled by an interrupt drivenalgorithm in the processor, which re-sponds to the 4800 Hz clock I nor-mally use for my tape cassette inter-face. A music interpreter of about500 bytes in length drives the system.The only major hitch with this par-ticular design as demonstrated was alack of digitally controlled filters toeliminate the high frequency harmonicsof the square edges which result Fromthe step functions used for the wave-form and envelopes. The result is a very

Photo 4: Ah, sweet success.

Photo 5: Explaining how the Klugehorn works,a short tutorial on last minute breadboardingand its results.

MVM 1024

$225

Microprocessor VideoModule

Sixteen 64-character lines, upper/lower case 128 character font.

Software-controllable reverse video characters.

Full read and write capability for both cursor position and character code.

Interfaces to any microprocessor: 8080, 6800, 6502, etc.

Scrolling, line/character insert/delete, etc. easily done with software.

THE SOPHISTICATED VIDEO MODULEFOR THE ADVANCED EXPERIMENTER

ASSEMBLEDAND TESTED

Write or call for complete literature

Riverside

ELECTRON*: DESIGN INC.

1700 NIAGARA STREET

BUFFALO, N.Y. 14207

716 875-7070

153

Why Wait?

•"-"

y"H

Up; ■ • -

(M|m« mm i

•^4

mmx

■ ■ |8™wff^: -IttflWft ■ i|j*p^^^-^

9^M:

MM*

mm

- rnen^" sMiBt'i^pBi'

3*-l J

-*:

mmlmmtmm.

The Tarbell Cassette Interface

Plugs directly into your IMSAI or ALTAIR*

Fastest transfer rate: 187 (standard) to 540bytes/second

Extremely Reliable — Phase encoded (self-clocking)

4 Extra Status Lines, 4 Extra Control Lines

37-page manual included

Device Code Selectable by DIP-switch

Capable of Generating Kansas City tapesalso

No modification required on audio cassetterecorder

Complete kit $120, Assembled $175, Manual$4

TARBELL ELECTRONICS

20620 S. Leapwood Ave., Suite P, Carson, Ca. 90746(213) 538-4251

California residents please add 6% sales tax"ALTAIR is a trademarWtradename of MITS, INC.

M6800 ADVANCEDSYSTEMS SOFTWARE

RT/68®

1*1/68° is mask-programmed on a 6830 ROM thatreplaces the Mikbug* ROM in your SWTPC 6800,Motorola Evaluation Module, etc. It is a powerful realtime, multiprogramming operating system with manyversatile system functions. RT/68® can support up to 16concurrent programs at 8 priority levels.

MICROWARE has improved the Mikbug* functions,added four more (Dump, Exec, Sys, Bkpt) and made tapeload and punch program-usable. RT/68e is designed soprograms that use Mikbug* I/O don't require changes.

• POWERFUL REAL TIME EXECUTIVE

• 100% SOFTWARE AND HARDWARE COMPATIBLE

• IMPROVED CONSOLE MONITOR

• EXPANDED PROGRAM DEBUGGING FEATURES

• SUPPORTS AUDIO CASSETTE I/O

• COMPREHENSIVE MANUAL INCLUDES SOURCELISTING

• IMMEDIATE DELIVERY

ORDER RT68MR $45.00 ppd.

THE MICROWVRE CORPORATION

RO. BOX 954 Des Moines,Iowa 50304

Write or use reader service card for free brochure.Phone Orders (515) 279-9856

BankAmericard and Mastercharge give all info on card.Mikbug* is a trademark of Motorola, Inc.

flexible synthesis system which canchange timbre in several ways: bychanging waveforms directly, by chang-ing envelope contours, and by changingthe rate at which envelope contoursare evolved. More on this later if andwhen I ever get around to writing anarticle in BYTE on the subject. (AsI write this, a real time music inter-preter for the Klugehorn has alreadybeen completed; it handles two proc-esses, allows waveform or envelopedefinitions, simple arithmetic timbremodifications, subroutines and othergoodies.)"

A Note on Omega

BYTE readers who are building theirown version of the Mini-0 Omega re-ceiver system [described by Ralph Bur-ham, February 1977 BYTE, page 62;March 1977, page 70, and by RichardSalter, April 1977, page 100] may beinterested in joining the InternationalOmega Association which publishesnewsletters and sponsors an annual con-ference for exchange of informationamong users and hardware-softwarebuilders. This year's conference is ex-pected to include a user workshop andprobably will be held this summer on theEast Coast. Write for information to:IOA, POB 2324, 1720 EADS St, Arling-ton VA 22202. Membership in the IOAis open to anyone interested in Omegaand VLF navigation problems for anannual fee of $ I 0.

Another organization of interest tonavigator types is: The Institute ofNavigation, Suite 832, 15th Si NVV,Washington DC 20005.The ION publishesa quarterly journal of the Institute ofNavigation (//ON) on all types of naviga-tional subects including Omega,Loran-C, Satellites, Aircraft, Geodesies,etc. Membership dues for the ION are$15 a year which include a subscriptionto Navigation. Several annual con-ferences are held each year.

Ralph Burhans

EE Dept, Ohio University

Athens OH 45701

Learn About and Take Home a Micro

Wintek has announced the Springschedule for their workshop, "Hands onMicroprocessor Short Course with FreeTake Home Microcomputer." Attendeesreceive a microcomputer to use at theworkshop and take home when theyleave. The take home computer has a6800, programmable memory, parallel10, serial IO, and read only memorywith Fantom-ll (which supports singlestep, break points, etc.) and is fullyexpandable to 65 K. Course schedule isMay 10-12, Lafayette IN; May 24-26,Cleveland/Akron OH; June 7-9, SyracuseNY; and June 21-23, Hackensack NJ.Tuition is $495. Wintek Corp, 902 N 9thSt, Lafayette IN 47904, (317)742-6802."

154

Continued from page 9

products to date based on a "typical" $42per 1024 installed bytes. At the bottom ofthe table is an estimate of the total size ofthe personal computing retail sales to datewhich is between 39.5 million and 58.3million using a conservative estimate ofmainframe and peripherals cost. While we(ie: computer enthusiasts and manufacturerswho serve them) are not yet as big as theauto industry, we've certainly made a re-spectable start for the first 21 months of theindustry's existence (counting the introduc-tion of the Altair as the origin in time,through the survey point of October 1976).This industry is still expanding as more andmore people enter the market both ascustomers and as suppliers.

Some miscellaneous but interesting re-sults from the survey include responses toquestions like "Do you have experience withthe assembly or machine language ofmachine X?", or "What is your experiencewith high level languages?". Table 2 sortsout the answers to the question of specificprocessor familiarity based on the total 1448respondents, and table 3 sorts out theanswers to the question of familiarity withvarious high level languages.

A final result which will be of interest toreaders is the nature of interest in specificapplication goals for small machines. Table 4shows the results, with rankings. Not sur-prisingly, the predominant interest was insoftware development. Why isn't this asurprise? Two reasons come to mind. First isthat software is intrinsically fun and chal-lenging for its own sake (read JosephWeizenbaum's comments on the compulsiveprogrammer, an extreme situation of addic-tion, in his book Computer Power, andHuman Reason). The second reason is thatsoftware development is a characteristic ofany activity which uses the computer.

I expect to perform additional surveys forBYTE in the future, since intellectual andbusiness curiosity demand it; we'll see howthe field evolves in the future, and documentit through this form of statistical measure.But this is enough for now. Copies of theElectro paper are available through the IEEEfor those who want more detailed informa-tion and and discussion of the survey. Thissurvey was probably the first publishedwhich has any direct basis in the actualdemographics of personal computers, sinceits target group comprises the largest knownset of such enthusiasts."

Table 4: Interest in hobby or home applications.

Application Using Intend

Software development 27% 52%

Interactive keyboard games 18.4% 53.3%

Graphics 6.8% 64.7%

Real time control (as in household

automation.) 6% 59%

Personal data bases 8% 54%

Games with analog inputs 3% 53%

Computer design 12% 42%

Educational, excluding games 9.9% 42.3%

Text processing 9.5% 42.3%

Non computer hobby 8% 35%

Serious: Intend + Using

Table 5: Interest in professional and business applications.

Application Using Intend

Mathematical or data analysis 27% 34%

Simulation or models 15% 33%

Professional data base 13% 34%

Text processing 12% 30%

As part of a communications

network 11% 29%

Accounting 8% 31%

Scheduling, planning 6% 27%

Inventory control 6% 26%

Mailing lists 6% 23%

Serious: Intend + Using

Serious

Serious

Rank

79%

1

71.7%

2

71.5%

3

65%

4

62%

5

56%

6

54%

7

52.2%

8

51.8%

9

43%

10

Rank

61%

1

48%

2

47%

3

42%

4

40%

5

39%

6

33%

7

32%

8

29%

9

Practical Microcomputer Programming: The Intel 8080

Here is a comprehensive source of programminginformation for the present or prospective user of the 8080microcomputer, an architecture which appears in the MITSAltair, 8800, Processor Technology SOL, IMSAI 8080,Polymorphics POLY-88, and other popular microcomputersystem products.

After several preliminary chapters, the authors get down topractical details with topics such as moving data, binaryarithmetic operations, multiplication and division, use of thestack pointer, subroutines, arrays and tables, conversions,decimal arithmetic, various IO options, real time clocks andinterrupt driven processes, and debugging techniques. Mostexamples are given in symbolic assembly form, withoccasional listings of assembled code using a ComputerAutomation software development system.

This 306 page hardcover book is well worth its $21.95price and should be in every 8080 or 2-80 user's library.

by W J Weller, A V Shatzel, and H Y Nice

Send now to:

BITS, Inc.70 Main St.Peterborough NH 03458

Master Charge and

BankAmericard Welcome

All orders must be prepaid

Price shown is subject to change without notice.

In unusual cases, processing may exceed 30 days.

155

r

16 K STATIC RAM

For ALTAIR / IMSAI / POLY 88

$459 kit

ASSEMBLED $529

• USES 4K STATIC RAMS-NO REFRESH

• VERY LOW POWER-LESS THAN 1 AMP

• Z80 FAST-200ns ACCESS TIME

• PROVISION FOR BATTERY BACKUP

• LOW PROFILE SOCKETS FOR ALL CHIPS

• EACH 4K ADDRESSABLE TO ANY 4K SLOT

• HARDWARE/SOFTWARE MEMORY PROTECTFOR EACH 4K

• SPECIAL PAGING OPTION ALLOWS UP TO1 MEGABYTE ADDRESSABLE MEMORY

• LOW COST

CONSTRUCTION MANUAL $1.75

PAGING OPTION $9.00

QUANTITY DISCOUNT 5 BOARDS — 5%

10 OR MORE —10%DEALER INQUIRIES INVITED

OMNI SYSTEMS INC.

P.O. BOX 7536, UNIV. STATIONPROVO, UTAH 84602

READER SERVICE NO. 198

MORE POWER TOYOUR ALTAIR*

12 AMPS @8v. (nominal)2 AMPS @ ±16v.

At any line voltage from:

90 to 140 volts.

Installs easily inside any Altair* 8800 or8800a.

Over voltage and over current protected.Conservatively designed and specified.

only $90.00

| postpaid in the U.S.A.California residents add$5.40 sales tax.

PARASITIC ENGINEERING

PO BOX 6314

ALBANY CA 94706

"Altair is a trademark of MITS Inc.

(jlubssndNewsletters

Conducted byPeter Travisano

Utah Computer Association Show

The Utah Computer Association will holdan informational show on Saturday, April30, 1-5 PM at the Fashion Place ShoppingMall, Salt Lake City UT. There is noadmission charge and there will be no selling.The purpose of the show is dissemination ofinformation on personal computing. Clubmembers will be bringing their own systemsfor. discussion and display. For moreinformation call Ernie Dixon, (801)467-9100, between 6 and 9 PM.

Homebrew Computer Club —Mountain View CA

Over the past several months we've fea-tured computer groups which appear to beoutstanding: New England ComputerSociety, Denver Amateur Computer Societyand San Diego Computer Society, to namebut a few. If one can judge a club by itsnewsletter, he/she would easily concludethat Homebrew is as its name implies, aunique and innovative club on the vanguardof the computer hobbyist field. Most of thearticles are thoughtful, technically accurateand written with consideration for thehuman as well as the technical side whenappropriate.

If you're in the market for a new idea ortwo, investigate the Homebrew cassettelibrary or subscribe to their newsletter andtake advantage of the programs they featureevery month. In any case, the HomebrewComputer Club is worth finding out about.Write Homebrew Computer Club, POB 626,Mountain View CA 94042.

Wisconsin Area Computer Society

In looking through the Homebrew News-letter, we came across word of the WisconsinArea Computer Society. According toHomebrew they've been holding meetingsfor the past 12 months and boast a member-ship of over 80 people. They're in theprocess of setting up a software library usingpaper tapes and cassette tapes. A newsletteris also available. For more information write

156

the microcomputer

an introduction toreality

now in Canada

imsaiprocessorcromemco

tdland more

The Computer Place186 Queen St. WToronto M5V 1Z1416-598-0260

Focus Scientific160 Elgin St.Ottawa K2P 2C4613-236-7767

ANNOUNCING

SUFFOLK COUNTY'S

NEW COMPUTER STORE

System Demonstrations, Soft-ware, Peripherals, Periodicals &Service For Hobby, Business &Educational Applications

THE COMPUTER SHOPPE

444 Middle Country Rd.Middle Island, N.Y. 11953

(516) 732-44461.6 miles east of Rt. 112

. '. '. fc '•

AT LAST

Universal cassette interface withlatched input port for keyboard orother use, switch-selectable from600 to over 12,000 baud, digitalcomparator—no adjustments, leveland sync lights, user-selectablesync character, relay controls op-tional for 2 recorders. Hardwaredetection of input level allowssoftware search for files. Altair,IMSAI, Kansas-City, Tarbell com-patible. Manual S4.50, kit $135Assembled $175 optional relays,$16, COD $1.50 Mastercharge/Bankamericard

DAJEN Electronics

7214 Springleaf Ct.

Citrus Heights, Ca. 95610

(916) 723-1050

COMPUTER MARTofNew Hampshire

Dealers for

IMSAI

Technical Design LabsThe Digital Group

Open Monday Thru Sat.

10:00-5:30

Thurs. 'til 9:00

170 Main St.

Nashua NH 03060

(603) 883-2386

Z-80COMPUTER

SYSTEM with Z-80 ProcessorCabinet and S-100 P/C BackplaneControls & Power Supplies, Manuals-Memory, 1/0 options

Kit $299.

ALTAI R/IMSAI/POLY/VECTORSystems & S-100 Modules

Z-80 Processor Board $149.

8080/6800 CPU Board 130.

8080A CPU & RAM/PROM 210.

S-100 Memory Modules4/8/16/64K RAM from 99.

2/4/8/16K PROM from 90.

1K RAM/2KPR0Mprov. 95.

I-O/Communications Mod. 85.

Video Dis'play/KBD Module 180.

3M Cartridge & Interface 290.

Floppy Disc & Interface 599.

COMPUTER SYSTEMS

(313) 779-8700

26401 Harper Ave.

St. Clair Shores, Mich. 48081

WHEN YOU NEED

SOLDER

DUNTON'S

SPECIFY: N0K0R0DE"PC." SOLDER

LET OUR REPUTATION GIVE YOU THAT

EXTRA MARGIN OFSAFETY.

AT FINE ELECTRONICS STORES EVERYWHERE.

MFG. BY:

M. W. DUNTON COMPANY350 KINSLEY AVE. — BOX 6205PROVIDENCE, R. I, 02940401 — 331- 3G00

MULLEN COMPUTER ROARHS

BOX 6214, HAYWARD, CA 94545

RELAY OnoS

ISOLATOR 2

„ CONTROL |

| BOARD $117 »

>5

Cft

>

O

8 fast reed relays respond to an 8 bit word: Feedthe relay associated with its bit a "1" and it closes, give ita "0" and it opens. Also, 8 opto-isolators accept an 8 bitword from the outside world and send it to your com-puter for handshaking or further control purposes.

Especially suited for model railroad, burglar alarm,audio switching, ham radio, music synthesizer, and auto-mated display applications, this board goes whereveryou need a general purpose 1/0 switching gizmo.

We're proud of the design work and quality put intothis applications-oriented peripheral; and with it, youcan take care of that 1/0 gap in your system.

Available in kit form only. California mail orders:add state tax.

2

<

8

I

*4TIBLE •AVAILABLE BY AA>

Confused About

ANSWER!

THE SSP-40

licroprocessor for easy connection

$575

TTYREPLACEMENT? THE SSP-40 ~5» I 9

The SSP-40 contains its own microprocessor for easy connectionto your seriaf port.'

LOW COST BUSINESS SYSTEM? . THEMP-40 "425

The MP-40 connects to your parallel port for ASCII data transfer

MINIMUM COST FOR HOBBYIST? ... THEKP-40KIT "l T 9

The KP-40 KIT contains mechanism and minimum electronics forconnection to your parallel port:

All of our 40 series printers use the same reliable 5x7 impact dot matrix mechanism withup to 40 columns per line on ordinary paper with a print speed of 75 lines/minute.

MASTER CHARGE WELCOME • UTAH RESIDENTS ADD ,5> SALES TAX

SEND FOR FREE LITERATURE

MICROPROCESSOR SYSTEMS AND PERIPHERALS

P.O. BOX 22101 /SALT LAKE CITY/UT. 84122

1801)566-0201

Don Stevens, chairman, Wisconsin AreaComputer Society, POB 159, SheboyganFalls Wl 53085.

Concord NH Computer Society

Good news for hobbyists in central NewHampshire: A computer group is beingformed: the Concord NH Computer Society.For details, contact Bob Vogal, 9 Ridge-wood Dr, Concord NH 03301, or phone(603) 224-9402 between 6 and 8 PM.

Santa Barbara Computer Association

The Santa Barbara Computer Assn has itsown newsletter. The premier issue was re-cently printed and it is a good first effort.Like most computer club publications, itsfocus will be around hardware and softwarereview, interviews with members, meetingannouncements and the like. Future meet-ings will be held the second Wednesday ofeach month at 8 PM in the Goleta Library,500 N Fairview, Goleta CA.

To find out more, get in touch withGlenn McComb (805) 968-3112, home, or(805) 967-4410, office, or write POB 2314,Goleta CA 93018.

A Computer Heathkit Users' Group . . .

... is being formed. For more informationdrop a line to CHUG, c/o Charles Floto,267B Willow St, New Haven CT 06511.

Amateur Computer Group of New Jersey

The Amateur Computer Group of NewJersey is where the action is in the GardenState. Attendance has been well over the100 mark at main meetings and meetings ofspecial interest groups. This is the groupresponsible for the Trenton Computer Fes-tival, among other activities.

If you're a computer buff in the GardenState you might look into Amateur Com-puter Club of New Jersey at UCTI, 1776Raritan Rd, Scotch Plains NJ 07076.

Triangle Computer Club, Raleigh NC

Hobbyists in the Raleigh area may wantto look into the Triangle Amateur ComputerClub. The club meets on the last Sunday ofthe month at Dreyfus Auditorium, located atthe Research Triangle Inst, Research Tri-angle Park, NC. Write Triangle AmateurComputer Club, POB 17523, Raleigh NC27609.

RAMS — Rochester Area MicrocomputerSociety

RAMS has been in existence since April1976, helping members by sponsoring group

158

LILLIPUTE'SCOMPUTER MART, INC.

NEWEST CHICAGOLANDAND MIDWEST DEALER OFI MSA I, SWTPC, APPLE, VEC-TOR 1, TDL, Z-80, TARBELL,SANYO CRTS, KEYBOARDS:WE GOT'EM.

FULL LINE OF IC, Manuals &Books with HARDWARE &SOFTWARE BACK UP & SER-VICE.

ASK US ABOUT THE NEWESTMICROCOMPUTER THE GUL-LIVER 1 at OUR STORE, NOW!

LILLIPUTE'S

4446 OAKTON ST

SKOKIE IL 60076

Phone (312) -674-1383

Ask for ED CURTIS Mgr.

P

0

w 1

SURPLUS

wM 1 u.iiffrdllP P

E

«■ I P

R !

CONTROL DATA

"If L

mm j. y

BARGAIN

* 5V @ 7A - 12V @ 2A+ 12V@2.5A +180 V@ 150 ma+30V @ 200ma (unregulated)-6.2V @ 25ma (no adj. pot)

Brand new. made by CDC (ormicroprocessorterminals. 110VACin, regulated and adjustable DCoutputs. Overvoltage protected +5,-12. Power status signal. Fan.Schematic. Original list $600+.From stock. UPS paid, custom foambox, guaranteed.

$50.00

ELECTRAVALUEINDUSTRIAL

BOX 464

Cedar Knolls. NJ 07927

(201) 267-1117

19" RACK S-100 BUS CARD CAGE

ECT-100 CARD CAGE KIT $100

CARD CAGE / MICROCOMPUTERS

ECT-100-8080 KIT $320

ECT-100-280 KIT $420

8,192x8 BIT STATIC MEMORYEXCEPTIONALLY LOW POWER

f-B B O'DI E IB '''■(■ B B B B B:B'" "

n.mmm

8KM MEMORY BOARD KIT $295PB-1 PROTOTYPING BOARD $28EXT-100 EXTENDER CARD $24

ELECTRONIC CONTROL TECHNOLOGY

P.O. Box 6, Union, New Jersey 07083

SPECIAL PACKAGE DEAL:

TVT-IH SYSTEM (with 4 page capa-bility! includes: Main and MemoryUnits, Screen Read, Manual Cursor,U.A.R.T. and Power Supply, all in kitform (minus keyboard and case): $160.One to a customer. Offer good untilJune 30, 1977.

Construction packet sold separately$2.50. (Kits still sold separately).

ANNOUNCEMENT:

We will now offer postage free shipping(in U.S. only), beginning with ordersfrom Catalog #9 or this ad. Send SASEfor inquiries and a free catalog.

ELECTRONIC

DISCOUNT SALES

138 N. 81st Street

Mesa. Arizona 85207

DISCOUNTS!

IMSAI 8080 KIT $599.

assembled

750.

IMSAI 8080 w/22 slot MB

645.

assembled

795.

RAM 4A-4

125.

assembled

225.

MULTIPLE I/O Board (MIO)

(both Tarbell and Byte modes one serial.

two parallel, one control port)

175.

assembled

275.

EXPM (100 pin w/edge conn

6.50

assembled 11.50

(POLYMORPHIC SYSTEMS)

16x64 CHAR VIDEO BOARD

189.

assembled

229.

BOOKS

101 BASIC COMPUTER GAMES

6.50

FUN & GAMES WITH COMPUTERS (A

BASIC LANGUAGE PRIMER)

5.25

GAMES & PUZZLES

1.20

*write for discount prices on

other

IMSAI products.

*N.C. residents add 3% state sales tax

CDiTIPUTER ELECTfiDriiCS

BOX 339

Cary, N.C. 27511

ET1 CRT

TERMINAL FEATURES

• 24x80 display, with anti-glare screen 8filter

• 12" industrial 15 Mhz monitor

• 90 day warranty (parts & labor. F.O.B.factory)

• 96-hour elevated-temperature operatingQ.C. test

• RS 232 and 20 ma interface

• LF, CR, BS. Local. Rubout, Break, Home &Clear, Tab*, Remote Cursor Placement*,and Scrolling*

• Micro-Processor based, with 63-keykeyboard

'These functions vary with the model selected.

CALL OR WRITE FOR MORE INFORMATION.

ECONOMYTERMINALS

Box 12261

Minneapolis. Minn. 55412|612) 522-1076

computerenterprise/

Your Mail Order Computer Shop...

IMSAI8080 kit with22 slots (limited quantity) $599.00

TDLZ-80ZPU (the one with full software availablenow) 242.00

EdgeConnectorsandguidesforlMSAI each 4.25

EdgeConnectorsanc/guidesforlMSAI 10for 40.00

Seals8kRAMkitwith500nschips 225.00

Seals 8k RAM kit with 250 ns chips 260.00

NorthStarcompleteMicro-DiskSystemkit 599.00

WETAKE

MASTER CHARGE OR BANKAMERICARD

For phone and mail orders...

(Add 4% of TOTAL ORDER for service charge)

TERMS: Shipping charges — $10. per CPU or large units, $1.50 per kit,

$2. minimum perorder.Provided stock is available, we will ship immediately for payment bycashiers check or money order.

Allow 3 weeks for personal checks to clear. New York State residentsadd appropriate sales tax.

PRICES SUBJECTTO CHANGE WITHOUT NOTICE.

Forthebestpricesavailableon:

IMSAI • TDL • NORTHSTAR • POLYMORPHICNATIONALMULTIPLEX • SEALS ELECTRONICS

CALL: (315)637-6208

WRITE: P.O. Box 71 • Fayetteville, N.Y. 13066

comptek. Boards DO Something

Hi

! i 1 1 1 § 1

i i i i i i i

CL2400

Real Time Clock

S98—Kit

S135—Assembled

If your system needs to know what time it is, our CL2400 isthe board for you. The present time in hours, minutes, andseconds is always available for input, and is continuouslyupdated by the highly accurate 60 Hz power line frequency.Need periodic interrupts? The CL2400 can do that, too, at anyof 6 rates. Reference manual with BASIC and assemblylanguage software examples included.

PC3200

Power Control System

PC3232 $299—KitPC3216 $189—KitPC3202 $39.50—Kit

$360—Assm.

$240—Assm.

$52—Assm.

If your system needs on/off control of lights, motors,appliances, etc., our PC3200 System components are foryou. Control boards allow one I/O port to control 32 (PC3232)or 16 (PC3216) external Power Control Units, such as thePC3202 which controls 120 VAC loads to 400 Watts. Opticallyisolated, low voltage, current-limited control lines arestandard in this growing product line.

P.O. Box 516

La Canada, CA 91011

(213) 790-7957

'Real World Electronics'

purchases, a club library, and coordinatingregional computer fests with other areaclubs. A newsletter is also available. RAMS islocated at POB D, Rochester NY 14609.

Southeastern Michigan ComputerOrganization

This Detroit based group has grown sub-stantially. Special interest committees cater-ing to individual members needs have beenestablished. One such group is SIGKIM, asmall group of avid KIM-1 users and other6502 based people. In fact, the group hasworked out well enough to warrant amonthly appendium to the Data Bus. If youare a KIM enthusiast, it might be worthsubscribing just to get that information.Anyway, if you're from the Detroit area, itwould be worth your while to check outSMCO. Write Southeastern Michigan Com-puter Organization, POB 9578, N End Sta-tion, Detroit Ml 48201.

Microprocessor Club of Sidney,Australia

Gary Lynch, a computer buff from downunder, was kind enough to send us a clippingfrom the newspaper, The Australian, whichcarried a story on the initial meeting of theMicroprocessor Club of Sydney.

Apparently, there's plenty of interest incomputers as evidenced by a fine turnout atthis charter meeting. Prospective membersshould contact Kevin Barns, ElectronicsToday, Sydney, AUSTRALIA.

Birmingham AL

Birmingham has its own computer grouppartly due to the Clubs and Newsletterscolumn. Jim Anderson wrote that "as aresult of your relaying my note to contactother enthusiasts in the Birmingham area, Ireceived several phone calls and letters andthe result is the formation of the Birming-ham AL Microprocessor Group."

Meetings are held on the fourth Sundayof the month, with less formal workshopsessions on the second Sunday of the month.At press time there is not a permanentmeeting place, so you'll have to get in touchwith Jim Anderson at 3905 Shannon Ln,Birmingham AL 35213. (205) 879-9630.

Want to Spread the Word AboutYour Club or Organization?

Well, that's what the Club and News-letters column is all about. Put BYTE onyour mailing list or send us a letter, andyou'll substantially increase your club's vis-ability; simple as that. New groups areespecially welcome, m

160

HOUSTON now has a full service

outlet for microcomputers and ac-cessories. Microtex, Inc., located inthe Southwest section of Houston,Texas carries product lines from thefollowing manufacturers.

• I MSA I •LEARSIEGLER

• SWTPCO • NATIONAL MULTIPLEX. TDL .ICOM

For your professional applicationor your own personal system, wecan help furnish all your computerneeds.

Microtex, Inc.

9305 - D Harwin Dr.

Houston, Texas 77036

713-780-7477

k

LOGIC

DESIGN

INC

QUALITY Support forthose who wish to dig deeplyinto digital design.

Breadboarding System, text-book on logic design, andcomplete schematics for anelegant CPU that will run thePDP8 instruction set.. $1095

132 IC's $ 87

TTY Interface $ 20

Memory $26/k

BOX 3991, UNIV. STATION

LARAMIE, WY 82071

(307) 742-7977

Advanced 8K EPROMMemory ModuleDoubles As Programmer

i^rmAMx.

Introducing

PitQROM

I Holds 8K BASIC Pius System Monitori S-100 Bus Compatiblei No Special Software Required-Write toF.PROMsJust Like RAM

• 512 Bytes of Ott-board RAM for Stack or

Scratch Pad< Shipped Witb One 256-Byte RAM and One

512-Byte EPROM pre-programmed with a

System Monitor

COMPLETE KIT 5164

MOUNTAIN HARDWARE

Box 1133B, Ben Lomond, CA 95005

ALDELCO COMPUTER

CENTER

NOW OPEN

Kits, Books, Boards, MagazinesSpecial 2102L1 8 for $17.50. Westock OK Battery Operated WireWrap tool $34.95, OK Hand WireWrap Tool $5.95. 7400 ICs CMOS,Timers PPL's. All kinds of tran-sistors, rectifiers, and diodes.Plus other electronic parts.

ZENERS

IN746 in IN759 ■1D0 Mw <•

a 25

1N4728to1N4 764 t w

CI06HSCR

S65

CA 3028A Oil Amp .

51 50

MPSA14

90

LM301 Op Amp

55

2N3056

LM309K Voli Reg

1 10

MPF102FET

45

L M380N Audio Amp

t 75

7N3904 m 2N3906

NE561BPLL

4.95

40673 RCA FET

1 55

LM709 Mm DIP Op Amp

45

556 Dual 555

1 75

LM741CE T05Op Amp

45

300 Vol! 25 Amp fli

rige

1 50

14 or 16 Pin IC Sockets

30

IN914 IN4148

15 lor 99

VVe havt Wire Wrap Sockets Hid

IN34 1N60 >N64

101

i 99

Wire Wrap Wiro 50 Ice

SI 98

Send stamp for our catalogue.

Open Mon thru Sat 9 AM- 5 PM

Wed till 9PM.

We quote on any device at any quantity. Min.order 96.00, Out of USA send certified checkor money order. Add 5% for shipping.

HIHUBHK

2281B Babylon Tnpk Merrick, N.Y. 11566(516) 378-4555

THE BETTER

BUG TRAP

The Better Bug Trap is anAltair/IMSAI plug-compatibleboard that extends system capa-bilities to facilitate softwaredebugging and real-time proces-sing. Capabilities include intervaltimer, real-time clock, watchdogtimer, processor slowdown, andclock with variable rates. Fourhardware breakpoint addressesallow you to stop processing orgenerate an interrupt at a break-point without modifying exist-ing software. The board servicesits interrupt with a CALLinstruction to ANY memoryaddress you choose. All capabili-ties may be set by software orfront panel. Write for freeliterature.

$180 assembled, tested, com-plete documentation, software.

MICRONICS, INC.

PO Box 3514Greenville, N.C. 27834

MICRO KITS

FROM

MICROTRONICS

BYTE READER-PaperTape ReaderKit $69.95

RS232C Interface Kit forBAUDOT TTYS 29.95

Regulator Kit for Micros5V@3A, ±12@1A 19.95

5V @ ViA Power Supply Kit 9.95

Altair/lmsai Compatible

8K Low Power Ram Kit $249.954K PROM Kit less proms 64.95

Video Display Kit 179.95

Extender Board 7.95

Edge Connectors 5 for 24.95

Shipping & Handling add $2.00

BAC/MC Accepted

CA res. add 6% sales tax.

Also ICs, Sockets, Resistors

and PROM programming.

Write for our FREE CATALOGUE

P.O. Box 7454BMenlo Park, CA 94205

NATION-STATES

GLOBAL-VILLAGE

INDUS-TRIAL

POST-INDUSTRIAL

Figure 3: Structures of Governing. In the traditional "nation state " from time immemorial political authority is concentrated ina strong central government. In Roman times, for example, the mode of communication was paper (papyrus) and mechanicaltransportation (chariot, ships, etc). When the costs of transport are high, the center-margin form of communications is the mostcost effective, minimizing the number of paths required. As technology developed, the cost of communications links hasdeclined. Such items as jet transportation, the automobile and electric communications have stressed the decentralized networkconcept through mass production and lower cost. The result for government might be called the "global village" or even the"network state. "

Continued from page 24

1) Golden Ager's Software Co

2) Folsom Prison Software Development Inc

3) Gray Panther Computer Diagnostics

4) Mother Goose Arithmetic Packages Ltd

d. The computer as a system for sale: Putting it alltogether (software, hardware, application pro-grams, peripherals, maintenance, customer trainingand documentation), the small business groupcould sell turnkey operations to customers withmore intensive data processing requirements.

1) Stock inventory system.

2) Word processing system.

3) Order processing system.

In general, developing the computer as a product couldprovide jobs, economic inputs, and self-supporting com-puter services for the community.

2. Political Power

Marshall McLuhan argues that the speed and capacity ofthe media (both communications and transportation) deter-mines the form and extent of human associations, notablystructures of governing (see figure 3). He contends that thecenter margin form, illustrated by a powerful centralgovernment ruling a large territory, was first actualized inthe Roman Empire through the use of papyrus andchariots, and came to its climax in the modern nation statewith its mechanized transports like tanks and automobiles.He further contends, however, that the electric media"creates centers everywhere. Margins cease to exist on thisplanet."10 More accurate would be to say that centers are

trying to exist everywhere, that the new speeded-up mediaare putting enormous stresses on our "mechanically based"forms of organization to make them compatible withcenters everywhere.

a. The computer as an extension of central govern-ment: It is obvious to many people that, withelectric media, authorities (senators, congressmen,cabinet members, etc) no longer need to belocated in close physical proximity as they arecurrently in DC. Conferences, debates, sharing ofdocuments, even back room confidences could beperformed using audio or visual or facsimiletelecommunications. Such techniques have beendeveloped and are used by corporations withwidely dispersed executives participating.

It is also obvious that citizens no longer need"representatives" sitting in a distant auditorium tovote on their behalf when, through the electricmedia, they could both be informed of the issuesand also vote directly. A "yes" and "no" button ineach of our homes would theoretically allowinstantly tabulated national referendums on issuesthat are now voted upon by only a few hundredindividuals.

I) Local administration of federal programs: Linecosts for data transmission now exceed otherhardware costs, thus discouraging transmissionof data from its source and encouraging theestablishment of local data bases near the

162

Pictured above is the new OP-80AHigh Speed Paper Tape Reader fromOAE This unit has no moving parts,will read punched tape- as fast as youcan pull it through (0-5,000 c.p.s),and costs only $74.50 KIT, $95.00ASSEMBLED & TESTED. It in-cludes a precision optical sensor ar-ray, high speed data buffers, and allrequired handshake logic to interfacewith any uP parallel I/O port.

To order, send check or money order(include $2.50 shipping/handling) toOliver Audio Engineering. 7330Laurel Canyon Blvd.. No. Holly-wood. CA 91605. or call our 24 hr.M/C-B/A order line: (213) 874-6463.

CANADIANS!

Eliminate the Customs Hassles.Save Money and get CanadianWarranties on IMSAI and S-100compatible products.

IMSAI 8080 KIT $ 838.00ASS. $1163.00(Can. Duty & Fed. Tax Included).AUTHORIZED DEALERSend $1.00 for complete IMSAICatalog.

We will develop complete applica-tion systems.Contact us for further information.

RotundraCybernetics

M

Box 1448, Calgary, Alta. T2P 2H9

Phone (403) 283-8076

TWX 610-821-1883

AS LOW AS $8.95 !

- NEV -

^-

H1CH QUALITY

TTTTTTT ¥ V

T ¥ V >T ¥ ¥

' ' 1

MOO -- KITS

1

Id

CONVERT ANY TVTOA HIGH QUALITY MONITOR

TRVM-1 Hi-Resolution $19.95Transformer isolated sets only.

HCVM-1 Hi-Resolution $23.95For EITHER transformer isolatedsets OR "HOT" chassis type sets.

RFVM-1 RF Modulator $8.95Ch.2thru6. Any TV source.

SHIPPINGS HANDLING, ADD $1.

VAMP INC.

P.O. Box 29315

Los Angeles, Calif. 90029

DEALER INQUIRY WELCOME

South Florida

Across from the University of Miami

University Shopping Center1238A South Dixie HighwayCoral Gables, FL 33146(305) 661-6042

Sunny Computer Stores, Inc.

South Florida's First Computer StoreWe Carry:

•IMSAI, COMPUCOLOR, VECTOR,SOUTHWEST, C.S.C., CROMEMCOPROCESSOR TECHNOLOGY,NATIONAL MULTIPLEX,•Books, Magazines, Newspapers•Sockets, IC's, Printers•Digital Cassette Equipment•Debugging Equipment•Full Service FacilitiesWe offer Classes, Friendly Advice andService

Hours: Monday - 1 2 Noon to 9 P.M.Tuesday through Saturday —10 A.M. to 6 P.M.

PROTECT YOUR INVESTMENT

Cover Your Altair/lmsai/SWTPCComputet

Is your computet chassis open andcollecting dust while you plugboards in and out trying new hard-ware configurations?

Our heavy vinyl cover will keepharmful dust and dirt out of yourchassis and protect it from scratchesand bangs. Specify make with order.

$6.25 + .75 Postage and Handling

JOYSTICK KIT

Control: Games; Interactive Graph-ics; Cursor Positioning; ProcessControl. No expensive Analog Inter-face required. Connects directly toone (1) output line and two (2) inputlines.

JOYSTICK KIT (Model QB690)$49.95 + $1.00 postage

Send check or money order to:

QUBED3

P.O. Box 7104

West Trenton, N. J. 08628

THE PROM SETTERREAD/WRITE

1702A and 2708

ALTAIR/IMSAI COMPATIBLE

NO EXTERNAL POWER SUPPLY

LET YOUR COMPUTERDO IT ALL

SOFTWARE INCLUDEDDoubles as an 8 Bit Parallel I/O

KIT COMPLETE $165ASSEMBLED $275

DELIVERY LESS THAN 60 DAYS

SZERLIP ENTERPRISES

1414 W. 259th St.HARBOR CITY, CA. 90710Calif. Res. Add 6% Sales Tax

people the federal program is designed to serve.The. uniformity of computer programs fromone local data base to another ensures theuniform application of the laws governing theadministration of benefits, but avoids the com-plexities, aloofness, and possible privacy issuesof a mammoth centralized data base,b. The computer as a tool for decentralizing govern-ment: While the electric media, including com-puters, can be used to disperse the administrativeand representative functions of central governmentas proposed in E2a above, this is merely throwing20th century gadgetry on top of an 18th centuryform of government. Such proposals are worth-while in themselves, but they do not tap theserious potential of electric media to decentralizedecision-making authority itself.1) Local administration of neighborhood pro-grams: As the authority to make health, educa-tion, welfare, and safety decisions becomestransferred back to the individuals who makeup a neighborhood government (through politi-cal processes outside the scope of this paper 1 1),computer based systems would be used to aidthe administration of these programs. Since thekinds of data to be collected from the recipi-ents, record update and purge policies, and theuses of the data are all controlled by aneighborhood government made up of recipi-ents, privacy abuses would be made as difficultas possible.

F. SUMMARY

A few examples of microprocessor-based applications forenjoyment, education, communication, and artistic andpolitical expression have been given. While these and manysimilar applications will become desirable, and com-mercially consumable products, home grown applicationsthat result from the merging of technology with humanvalues, or a "liberating" philosophy, will continue to havepotentially great impact on the organization of modernlife."

G. NOTES

1. DE Thomsen, "Beating the Game," Creative Computing,January-February 1976, pages 22-23.

2. A recent controversial model of world resource and populationdynamics can be found in The Limits To Growth, D LMeadows, et al, Signet, 1972.

3. E C Berkeley, "Newspeak and Computers: What We DoDepends Upon What We Think," Computers and People, pages6-8, 12, 19.

4. C Johnson, "Span-O-Vision" cartoon, Creative Computing,January-February 1976, page 12.

5. M McLuhan, Understanding Media, McGraw-Hill, 1965.

6. J Whitney, "Further Reflections of a Culture Savage," SCCSInterface, February 1976, pages 22-23.

7. Any introductory psychology book will describe Skinner'smajor findings. For his view that culture is a Skinner box seeBeyond Freedom and Dignity, Knopf, 1 971.

8. T H Nelson, Computer Lib/Dream Machines, 1975. Also "NoMore Teachers' Dirty Looks," Computer Decisions, September1970, pages 16-23.

9. M Kotler, Neighborhood Government, Bobbs-Merrill, 1969.

10. McLuhan, op cit, page 91.

11. Kotler, op cit.

Goodbye, microcomputer, it was fun...

Hello, Minicomputer!

This is the heart of an S-100 buss compatible minicomputersystem. Upgrade your present machine with this board or forma custom system around it using S-100 buss peripherals.

There are a lot of good microcomputers on the market. But that's all they are:microcomputers. Difficult to use. frustrating for program development. Full of blink-ing lights and CPUs that go to sleep when you halt the program.

The Sigma-100 Minicomputer CPU Board (with integral front panel) allows youto gain control over your machine. Run your program, or if you wish, step it at anyrate from 1 to 1000 steps per minute ("Slow Step"). By simply stopping the machine,you may examine and alter processor registers, memory locations, and 1/0 devices--there's special firmware to keep the CPU from going to sleep ("Control Halt"). Youcan monitor all of the above during execution of the program as well. Everything isfront panel controlled by your fingertips through a 12 pad keyboard; octal data readsout on unambiguous 7 segment displays.

At last, a machine where you can examine, alter, and monitor every funtion of theCPU/front panel and its operation in real time. Edit or modify your program whileyou run it. . .think of what this means in terms of extra productivity, reduced frustra-tion, and greater speed.

The implementation matches the concepts, with onboard regulation, sockets thatprevent soldering damage to ICs, low power Schottky ICs that save energy, buffersfor full isolation. . .in other words, quality.

We invite you to send for our flyer, which gives additional details. If you're curioushow we did it, send for the board's documentation package ($5.00).

Available by mail and at many computer stores.Kit form: $250 Assembled/tested: $325

Advanced Microcomputer Products Presents

Prototype Design Equipment

Ilill 1

STJS H 5 !3;f!—* IH—

Micop'oceuoi PrototypingNEW SOCKETS & BUS STRIPSE.Him.mMeoo $10.95

8K RAM BOARD S198.00

ADy

QMPUTER

* MICROPROCESSOR PRODUCTS

MiB'iOWHOMII83SI.B34 i

IS (10 *tO?A

I-j 00 4?011

•in 9I31APC

'600 9M1APC

fi ?*> AMZ40I

•I'll) AMMIM IItl 95 MM500H

I5-9S mmsoiiih i

* IC MARKET PLACE *

IM370T I]IM17UI 11LMJJ7« '.LM174M

LM5S6CN

LM565NLMSfiSHLM703CNLM/09HLMJ09N

now

74DJN740BN

Ml UN

74190N S

741J5N

>a

7419IN J

70

74193N J

74 MSN

74 ISSN

74147N

169

74190N

7414BN

1 79

74197N

1 15

9B

74I99N %

741S4N

74155N

M

809 3N

741S6N

99

8094N

74ISTN

«S

809SN

SPECIALBUY 10OF THE FOLLOWINGAND YOUR PRICE IS . .

AMD 80HOA S19 95

AMD 9111 . 1 10

AMD 9113 2 30

RF MODULATOR MODULE

NEW PRODUCTS

F4702B.wd I1..I. Gen. 15.95

82 m Priority Im 11.95

Z80CPU 49.95

ZHO 3881 PIC 9.95

280 3882 CPC 9.95

I'D 37? Floppy Contmllei 55.00I'D 371 Mag. Tip* Contralto 49.95

APPNouttat 372 Floppy S-86

01 AYS 3550 4K Digit DVM 29.95Gl AY5 3G00 Keyboard Encoder 14.95

Intersil 8038CC Wave Gen 3.50

AY3507 DVMChlp 12.95

1103 2513 Upper«a» B.96

R03 2513 Lowercase 10.95

TMS40GONL 2 IK RAM 3.95

MM09G4K HAM 3.95

1G02B UART 5.50

1883 UART 6.50

AY51D13A UAftl 5.8Q

5101C E IK CMOS RAM G.95

WD 1G71BA«ioi 29.95

WD 1911 Oli-iI Baud Gl^ii 9.95

WD 1771 Floppy Disc Com 71.95

6330-1 2S6BitOC Pram 2.95

6331 1 25G Bit TSProm 2.95

G300 1 IK OCPtorn 3.50

G301 1 IK TSProm 3 50

6305 I 2K OC Prom 9.95

G30G 1 2K TSI'iom 9.95

G340 1 4K OC Prom 18.95

G341 1 4K IS Prom 18 95

G352 1 4K OC Prom 18.95

G353 14K TSProm 18.95

rung ci

"Mrci

inly S9'J.r,0Mii:r()Coil1|)Li[i'r A|l|)lic.only S7.9Sl.rtil B080 Mtcroidiicus

nd li

mpli

7S492N75493N

7S4MN

100 PIECES MIX TAKE 10% DISCOUNT1000 PIECES MIX TAKE 15% DISCOUNT

SL107OC ISS SL1645C BW

SI 1671C ?'Hi SI II.'jOC B7!

SLienc ju'j 5U1BS1C <si

SL1II73C 199 S11I.B0C 17!

DIVIDERS

SPBGDte 475 SPBWIB BBS

SPB90N 16 00 ".PR67/B bSO

SPHbO.31) 14 SO SPS63QB 70 00

SPSeOUl H7b SPHMIR 17 00

SPH607H 17 00 SPHr.J7B 10 On

SPHMlll 17M sPHIiTtB 1SO0

U-llhMII 1H00 '.CIMijr.H 11'.It

SMttU 70 00 M-UhlBH Z7MI

SPBtllrU 22W SPH637B 1800

6800

STARTER SET

8080ASTARTER SET

All shipments first class or UPS

tor shipping and handling. Mm

California Residents add6% ta»

n U S or add 5"u

num otdei $10 00

Foreign add B°*>

DI mrU P.O. BOX 17329 *V • „b1«lWc*

Jr U 1 CJri IRVINE. CALIFORNIA 92713 0„ot«yo

PHONE 1714) 9683665

00

o4*

P

P

I

>*

to

3

00

PP

*

WIREWRAP SOCKETS - GOLD

14 Pin WW 1 level .30

14 Pin WW 2 level .33

11 Pin WW 3 level .37

16 Pin WW! level .31

16 Pin WW 2 level .34

16 Pin WW 3 level .38

18 Pin WW 3 level .60

24 Pin WW 1 level .70

24 Pin WW 2 level .75

24 Pin WW 3 level .85

40 Pin WW 3 level 1.25

EDGE CARD CONNECTORS

IMSA1S100 WW .250" Row Spacing ....

S5.00

IMSA1 S100 ST .250" Row Spacing ....

5.00

Altai

S100 WW Wire Wrap

5.50

Altai

SIOOSTSoldertail

5.25

D-SUBMIN CONNECTORS

RS-23225 Pin Male Part No. DB25P ....

S3.50

RS 23225 Pin Female Part No. DB25S. . . .

3.95

RS-232 Plastic Hood for above

75

no vcm i c Miaoiirocessors TimcbasusCRYSTALS w Games Premlon Crys,al<

Frequency

CSH

Price

Frequency

Case

Price

1.000 MHz

HC6/HC33

4.95

13.000 MHz

HC18

4.95

2.000 MHz

HC6/HC33

5.85

14.31818MHz

HC18

4.95

2.097162MHz

HC6

6.95

18.000 MHz

HC18

4.95

4.000 MHz

HC18

4.95

20.000 MHz

HC18

4.95

5.000 MHz

HC18

4.95

32.000 MHz

HC18

4.95

G.000 MHz

HC18

4.95

lOOKc

HC13

12.95

10.000 MHz

HC18

4.95

3579.45 Kc

2.4576 MHz

HC18

4.955.95

^Exar

* ruNCTionarT,

* tIMING CIRCUITS

XR5SSCP

XR55GCF"KRZSSGCP

XR2J40CP

XHiZIICF

XRS67CP

xnjM67CP

* COMMUNICATION CIRCUITS*

TEHEHOECrjOtRK*

* JUNCTION GENERATORS *

XH7Z0GCP " ■ ■

• OPERATIONAL AMPLIFIERS*

XH4SSBCPXR4136CPXI14Z07CP

2708 PRIME

only $49.95

Build Your Own MONITOR

Now in Stock - NEWM3000 - 100 12-inch display module S229.00

M2000 155 9-inch display module S208.00

•Add S10.00 Shipping

MOTOROLA Exorciser, MEK6800DIand MEK6800D2 Compatible Modules

9601 16 Slot mother board ■ Inc. Conn- S175.00

9602 16 Slot card cage 19" rack mount S 72.009610 Utility Prototyping Board S 36.009615 4K Eprom Module I1702AI S350.009620 Parallel I/O Module S375.009626 8K Static Ram Modulo S350.009650 8 Channel Duplex Ansyn I/O S390.00

All assembled and tested. Not Kits

'-4f MISCELLANY ,^%> ~~

" ™ 4 ELCO VARIPAK 7 11 1 ,

"""'" "~~-—-. 4'si.oo" rr?J» -

Toucurorjt v«

XtYHOASO^

. ...-.'"^'v' '■ ' J """'in''' Onlv S9.9!

Only S3 95

CLOCK CHIPS

TP»

'VARIABLE RESISTORS

CORCOM EMI FILTER

ROTARY SWITCH

■si)4«jH/1™ ,'ijovix: f^~~^

'VAC Qv»yS*M " -i^r.^Vi P-' '

> ngg*******

COMPUTER-WAREHOUSESTORE

DEPT B •58'* COMMONWEALTH AVENUE* BOSTON, MA • 0221 5 • 617-261-2701 • VIS IT US: 9-9 WEEKDAYS; 9-6 SATURDAYS

ONE DAY SHIPMENT

PERIPHERALS FORMICROSYSTEMS

ALLanASR33isand MORE!

RS232 INTERFACE, QUIET OPERATION,10 CPS PRINTER, BUILT-IN PAPERTAPE READER/PUNCH, ELECTRIC TYPE-WRITER KEYBOARD WITH ADDITIONAL10 KEY NUMERIC PAD, YOUR CHOICE OFFRICTION OR SPROCKET FEED, LIGHTEDPLATEN AREA FOR EASY READING,STANDARD PAPER AND TAPE, SUPPORTEDBY OLIVETTI.

TALLY T132...$450+ shipping 150 i»

7 x 8 DOT MATRIX IMPACT

PRINTER HAS A SINGLE i^

LINE DYNAMIC MEMORY AND -\

A UNIVERSAL INTERFACE TO

ACCEPT PARALLEL DATA, FORMS

TO 1^-7/8 IN. WIDE, SIMPLE PRINTING MECHANISM

USES 132 SOLENOID HAMMERS AND TWO STEPPER MOTORS

FOR 100 LPM, 132 COLUMNS, (>h CHARACTERS

SPECIAL DISCOUNTS!

ON KITS & ASSEMBLED UNITS

SAVE UP TO 201 OFF KIT PRICE WHEN A PERIPHERAL ISPURCHASED AT THE SAME TIME.($200 MAXIMUM DISCOUNT)

PERIPHERAL OVER $900 ■■► 20% OFF KIT

PERIPHERAL OVER $250 ■■? 10% OFF KITPERIPHERAL OVER $95 HH^ 5% OFF KIT

+ SHIPPING

$875

165 lb

DIGITRONICS D507.....$95

+400 lbSHIPPING

PAPER TAPE READER, HEAVY DUTY PS, 3 MUFFIN FANS,POWER CONTROL PANEL, CIRCUIT BOARDS, RELAYS IN CABINET

KDI ADTROL AR-21...$95s;,pp?ng

ELECTRO OPTICAL PAPER TAPE READER WITH 110V PS, STEP-PER MOTOR, 250 CHAR/SEC, FAN IN TABLE TOP HOUSING

IBM 731 I/O WRITER $750sh.pp?ng

8i"PLATEN,PINFD,EBCDIC,U/L CASE,DUAL CLR RIBBON,115V

GREEN PHOSPHOR $150VIDEOMONITOR sh^.ng

STANDARD IV P TO P COMPOSITE VIDEO INPUT,16 MHz BAND WIDTH, RASTER SCAN 12x12x13"WITH POWER SUPPLY, VIDEO AMPLIFIER, DRIVING CIRCUITRYVENTILATION MUFFIN FANS, 7x9" HORIZONTAL VIEWING,CAPABLE OF 2b LINES x 80 CHAR., ANTIGLARE i" ETCHEDGRADIENT DENSITY FACE PLATE, P39 GREEN PHOSPHOR, ON/OFF BRIGHTNESS CONTROLS, 115Vac, 60 W ... TRULY ACOMMERCIAL UNIT BUILT TO WORK IN A DEMANDING ENVIRONMENT.

DATAPOINT 3300-200 $475

THERMAL PRINTER

PARALLEL PRINTER WITH ADDITIONAL CIRCUIT

BOARDS TO PROVIDE SERIAL INTERFACE, PRINTS'"

UP TO 30 CPS, 100Vac PS USES WIDELY AVAILABLE

NCR PAPER, 96 CH, ASCII, 80 COL, CRT COMPATIBLE 5x7

DOT MATRIX, SOLID STATE WITH LESS THAN 25 MOVING PARTS.

DATAPOINT CONSOLE PRINTER

$395

+ 285 lb.SHIPPING

MM Iff i HIGHLIGHTS FROM OUR

IV I I *> * WIDE SELECTION

IMSAI 8080 MICROKITS

8080A KIT 5 SLOT $699

8080A KIT 22 SLOT 751

4K MEMORY KIT 139

PIC-8 PRIORITY INTERRUPT 125

SERIAL I/O KIT 125

PROM 1|-512 KIT 165

UCRI-1 KIT 59

CABLE A KIT 18

STANDARD INPUT/OUT INTERFACES.

HANUALS, SOCKET SETS

VIKING 100 PIN, HEAVY DUTY $3.00

SWTPC 6800 $395

•512 BYTES of ROM• RS232 or 20 rnA•SERIAL INTERFACE•*K of RAM

«K MEMORY

MPA U5 MPB

MPC 1)0

MPE 1<I.95

MPM 65

MPP 35

MPS 35

MPMb lit. 50

MPCb, MPSb, MPLb,

CONNECTOR SETS MPU/MEM

CONNECTOR SETS INTERFACE...

"iKBA 5 GT61

AC30 AUDIO INTERFACE

PPllO PRINTER

CT 102*4 TERMINAL KIT

CTP 15.50 CTS

ALL SWTPC UNITS ARE Kl

MPD..MPF..MPMx.MPL-.MPAb.

..$100. . I10.. 35. . 30■ • 35• • 35. 14.50

EACH.

TS

..9.50

..2.50

2

• • 99.79.50.. 250

• • 275•39.95

SHOKE SIGNAL BROADCAST 16k RAH 595

LEAR SIEGLER ADM-3A

W/Cursor Control

•12" CRT

•lli LN X 80 CHAR•RS232 tp

\_^~^ «20 mA LOOP *0/O

SCAMP KIT $99

FROM NATIONAL SEMICONDUCTORKEYBOARD KIT 95

• BUILT UNITS •ICOM MICROFLOPPIES

PLUG COMPATIBLE FOR: j...,

$100 BUS. . .FD2<ll I $1095

SINGLE DRIVE FD2l|02 $ 6^9

I COM FLOPPIES:

FF36-1 FRUGAL $1 195

FF36-2 DUAL FRUGAL 1.395

360-58 BLT;INTFC 8080.. 300S17I POWER SUPPLY ... 250FD360-2-5DUAL SYSTEM... 3000

KIM-16502 $ 2A5

KIM-2 *(K 179

KIM-3 8K 289

MANUALS PACKAGE 15

TARBELL AUDIO CASSETTE KIT 120

INTERSIL INTERCEPT JR. $zei

I 2K RAM 1 <l5

ROM/PROM BOARD lh . 65

YOU ADD MEMORY CHIPS

SERIAL I/O 81.50

AUD I 0 V I SUAL BOARD 125

BOTH UN I VAC AND SINGER BUILT THESEPRINTER MECHANISMS WHICH OPERATE AT30 CPS FROM A ROTATING WHEEL. 65 CHAR.USES STANDARD FORM FEED PAPER. PINWHEELIS INTERCHANGEABLE.

UNIVAC 0769-06 PRINTER MECHANISM ONLY ... $195INCLUDES MOTOR/PRINT WHEEL +SHIPPING 751b

KLEINSCHMIDT 311 $250;h?pp1ng

THIS 30 CH/SEC DRUM PRINTER SITS IN A SOUND-PROOFENCLOSURE. 6*t CHAR, PARALLEL INPUT, 80 CHAR/LN

TECHTRAN4100 $595sh?pMSg

TAPE CASSETTE DRIVE. CAN RUN DIRECTLY FROM TERMINALINDEPENDENT OF CPU. FULL EDIT CAPABILITY.

TO ORDER EQUIPMENT

1.ENCLOSE CHECK FOR FULL PRICE PLUS SHIPPING CHARGES(KITS - ADD $5 IF UNDER $100; $10 IF OVER)BANKAMERICARD 6 MASTERCHARGE ACCEPTEDSEND CARD NUMBER, EXPIRATION DATE, INTERBANK ft2.CLEARLY IDENTIFY SHIPPING ADDRESS3.DESCRIBE ITEM BY MODEL NUMBER

ALL MERCHANDISE WARRANTEED

SEND $1 FOR OUR CATALOG

INCLUDES DESCRIPTIONS OF OUR COMPLETE LINE OFKITS £ UNITS, REVIEWS OF OVER 150 BOOKS, LISTOF NEW 6 SURPLUS PARTS AND ARTICLES -"ALL ABOUT PERSONAL COMPUTERS"

11 =

BILL GODBOUT ELECTRONICSBOX 2355, OAKLAND AIRPORT, CA 94614

TERMS: Add 50c to orders under $10; over $10 add 57. forshipping & handling. BankAmericard®/Mastercharge®: call(415) 562-0636, 24 hours. Cal res add tax. No CODs.

*****

****#*#***** :

[ MA[E~~

uouuuuuoo

J~

25 PIN RS-232CONNECTORS: sub-mini D type.

Male plug withplastic hood,part ?DB25P S3.95

Female jack,part #DB25S S3.95

JThis is not another painted box, but is equivalent to the fancy!:;^enclosures used for industrial and computer oriented equipment. |:;:Tasteful matte color scheme and extensive use of brushed alum-*oinum add to the beauty. It's shipped knocked down for easy*:;l;drilling, machining, or labelling, and is easily assembled: now;:;:*you can wrap your project up in style. i£

S There are no screws or fasteners to mar

:; the lines of these beautiful enclosures.

;i Has provisions for card guides, connec-

J: tors, etc. on the inside. Available in

J black or computer blue with white front

< panel; shipped unassembled.

i MP5-17-17U 5.51 "H, 17.58"W, 17. 1"D$79.25

:; CVP7-17-17U 7.26"H, I7.58"W, 17.1"D

;l $84. oo

9.01"H, 17.58"W, 21.6"D orsize as I MSA I microcomputer.S96.50

#UP9-1 7-1 7Uexact same

This beautiful, brand new SPDTminiature switch is designedfor PC board mounting [bushingnot threaded). Includes mount-ing frame for extra support.PC MOUNT ORDER #SW-3

ALSO AVAILABLE: Standard min-iature SPOT toggle switch, w/all mounting hardware. $1.15each or 5/$5.00STANDARD ORDER #SW-2

y<4

tils

'jfjii

I

74LS00

SO.36

74 LSI 39 1

38

74LS01

0.36

74LS155 1

38

74LS02

0.36

74LS157 1

25

74LS04

0.42

74LS160 1

85

74LS08

0.3S

74LS161 1

8b

74LS10

0.36

74LS162 1

85

74LS11

0.38

74LS163 1

85

74LS14

1.38

74LS168 1

8/

74LS20

0.56

74LS169 1

8/

74I.S21

0.38

74LS174 1

38

74LS22

0.38

74LS175 1

35

74I.S27

0.38

74LS22I 1

38

74LS30

0.36

74LS240 1

88

74I.S32

0.38

741.S257 1

25

74LS37

0.53

74LS258 1

3o

74LS3S

0.53

74LS273 2

25

74LS42

1.25

74LS2S3 I

20

74LS74

0.56

74LS367 1

00

74LS75

0.85

74LS36S I

00

74LS109

0.60

74I.S377 1

88

74LS124

2.50

74LS37S 1

.iS

741.S125

0.75

S1LS95 1

15

74LS126

0.75

81LS96 1

13

74I.S132

1.50

811.S97 1

13

74LS138

1.38

81LS98 1

15

SEND FOR FREEFLYER t

ECONORAM EC0N0R0M

KIT: $100 HIRED: $130 g Our family of ECONOROM boardsj

:;: ■:■ oiters 3 different capacities ■:

S 4K X 8, S-100 buss compatible j: 0f eraseable ROM... suitable;:

I full feature memory. Guaran- gs for holding any program or 5

j: teed faster than 500 ns, cur- ;i routine you want. Similar to I

I rent draw under 750 mA. ..both | ECONORAM, and also very low ::

| specs over full temp range. S power: 5V@^A, -12V@150 mA. ;i

5 Fully buffered; DIPSWITCH ad- | 2K X 8 BOARD $135 j:

;;; dress selector; sockets inclu- £ 4K X 8 BOARD $180 :■

| ded for all ICs ; uses lo-power S 8K X 8 BOARD '. . $270 :•

| Schottky support ICs: the best | 4K 8080 SOFTWARE BOARD. .. $190 |

:;: combination of value and econ- v |:

I °-v I ALL PRICES ARE FOR KIT FORM J

5A BIG, BRIGHT .5" DIGIT.i* VECTOR'S

i-SHOwN actual size i—»■;:; MCI 1T_W-WRAP" ^~~N'

is Hi $24-50 iH

*■ ■■■ I +2 lbs postage ^^^^^^^^

iSX^rJl/^J^J 3| s~-~^^^ a manual wrap~>

vr-imnn tn nr': / ~^<^^^ P' nq device, which;:

|FND510 COM, ANODE.., »0.95|/ J0C sgppi|es Icsulatid «ir=|

:;:r-Mnrn-7 <tn nr'' I -"^T (\ directly to wrapping posts:;

;;;FND503 com, cathode SO,95|\ fl %J uithout pr;-strippi„g „r PrE-i;

S,n nE r\UC V1UTI tfi Crfi \- */^S cutting. More than one level i

|10 OF ONt KIND »8.MJ::: of brap is rare]y required.5

6 |:| Speed your breadboard i ng time-;:|:=p=| rp=| =^l ii=|i §1 111 |j ?l:|: tremendously with this tool, and:;•:* ^ w^^i^E^ ilPli|/6\rL ^■:-:clon't botner stocking all that pre - st ripped :jl:-'^^!^! ^w/y«^^^' JRd pre-cut wire you would normally require.;:

4%HViWViWWilWWmV

Now you have a choice--specifywrap pins fiI lust rated) or soldertail with .250" row spacIng- For IMSAI andAltair peripherals.Wire wrap part SS-100WW. Solder-tail part K S-100STtS-IUUST is ideal fothe IMSAI motherboar

V^vvvvvvvvvvvvvvvvvvvvvvv

Clow

PROFILE

sockets

WIRE^WRAP

Soldertail, tin plated

14 pin 10/$1.95

16 pin 10/$2.15

18 pin 10/$2.75

20 pin 10/$3.10

22 pin 1.0/$3.50

24 pin 10/$3.60

36 pin 10/$5.50

40 pin 10/$6. 15

3 level, gold plated

14 pin 10/$3.70

16 pin 10/$3.85

18 pin l/$0.75

22 pin 1/$1.50

24 pin 1/$1.00

28 pin 1/$1.25

36 pin 1/$1.35

L36 pin L0/S5.50 36 pin 1/$1.3540 pin 10/$6.15 40 pin 1/$1.75 J

*

^VECTOR!

w This is one of the neatest Altairaccessories we've seen. It acceptsvirtually any size IC package, has apower and ground plane on oppositesides of the board for extra capacitance.Room for *t regulators, 1 heat sink provid-ed with board. By the way, the socketsare shown only for illustration, but theyget the point across that you can stuff a

lot of ICs on here implement your own

memory boards, 1/0 boards, etc.

\ 11

"IF

yilliijii

:!■

I

UNIVERSAL PROTOTYPEBOARD » * » $19.95

BILL GODBOUT ELECTRONICSBOX 2355, OAKLAND AIRPORT, CA 94614

TERMS: Add 504 to orders under$10; Cal res add tax. Place Bank-Americard or Master charge orders viaour 24 hour phone line, (415)562-0636. ALL PRICES ARE INTRO-DUCTORY SPECIAL PRICES TOCELEBRATE THE COMPUTERFA IRE.

8K X 8 Econoram II tm Price is $163.85 - 1/4<tf per bit!

Uniquely configured as 2 separate 4K X 8 blocks (with fully independent protect and address decoding to increaseflexibility), our Econoram II kit features full buffering, guaranteed 450 ns or faster speed (use 1 wait state with Z-80 . . .all necessary logic included on board), plated-through, double-sided Epoxy glass board with gold edge fingers, low profilesockets, on board regulation, and Tri-State outputs that can drive the Altair/IMSAI S-100 Bus or any bidirectional Bus.

We use proven, reliable technology, like static 2102L-1 low power 1K RAMs, and low power Schottky IC's which keepcurrent consumption to an absolute minimum. And there's more — but seeing is believing. If you can't see us at the Faire,send $1.00 to cover costs to "Econoram II Logic Print/Documentation", c/o our address, and you can see the full storyfor yourself. When it comes to memories, we've learned how to push the quality up . . . and the prices down.

MOTHERBOARD: $80.00

Use with the IMSAI machine as an add-on room for ten peripherals, or for starting a stand-alone system. Comes with 10edge connectors — lots of places would charge you the cost of our Motherboard for these alone. Active, regulatedterminations included on-board, minimize the crosstalk, noise, overshoot, and ringing that appear as mysterious gremlins inyour computer's data handling capabilities. And of course, we use an Epoxy glass board, with bypass caps and heavypower traces included. Get yourself one of these, a Morrow's Front Panel, some Econoram It's, and a power supply, andyou're on your way to a powerful system at a really good price.

TR-160B Standard UART IC$5.50 Brand new, prime part.

ft

BILL GODBOUT ELECTRONICSBOX 2355. OAKLAND AIRPORT. CA 94614

A readout blockbuster: FND359 0.4" 7-segment readout,common cathode. Pin-for-pincompatible with FND 70.FIFTY CENTS EACH 10 for$4 or 100 for $35.

ALTAIR OWNERS - finally a goldplated soldertail edge connectorwith 0.140" row to row spacing foruse with Altair Motherboards. Samequality features as our IMSAIMotherboard — compatible edgeconnectors. $6 each 5 for $27.50.

o;'CRYSTALS gT

"* -■ ^ __ THESE FREQUENCIES ONLY ~jbfa"

Part 4 Frequency CasB/Slyle PrTce"

CYIA I 000 MHz HC33U $5.95

CY2A 2 000 MHz HC33 U S5.95

CY3A J 000 MHz HC18U S4 95

CY7A 5.000 MHz HClfl.'U S4 95

CY:?A 10 000 MHz HC18U S4 95

CY'4A 14 31818 MHz HC18U S4 95

CY:9A 18 000 MHz HC18/U S4 95

CYZ2A 20.000 MHz HC18U $4 95

CY30B 32 000 MHz HC18/U S4 95

XR-2206KB Kit S27.95

WAVEFOHM

GENERATORS

iR-205 SS 40

:R-32Q6C? JJ9

iR-220/CP 3 85

XR-2206KA Kit S17.95

STEREO DECODERS*R-1310CP S3 20

"R-1310EP 3 20

ifi-lBOOP 3.20

xR-2557 299

EXAR

MISCELLANEOUSXR-2211CP S6.7

XR-J136 9

IRU68 3B

TIMERS

XH-555CP & 9

KR-320P I 55

\R-556CP 1 65

XR-2556CP 3 20

XR-2240CP 3 25PHASE LOCKED LOOPS

XR-210 5 20

xR-215 6 60

XR-567CP 1 95

XR-567CT 1 70

CONNECTORS

PRINTED CIRCUIT EDGE-CARD

.156 Spacing-Tin-Double Read-OutBifurcated Contacts — Fits 054 to .070 P.C. Cards

15 30 PINS (Soldei Eyelet) S1.95

18*36 PINS [Solder Eyelet) S2.49

22.44 PINS (Soldei Eyelet) S2.95

50 100 i 100 Spacing) PINS (Soldei Eyeiet) S6.95

25 PIN-D SUBMINATURE

DB25P PLUG S3.25

DB25S SOCKET S4.95

m DIGIT DVM KIT

Tins 0-2 VDC 05 per cem digital voltmeter features the Motorola 31 i digitDVM chip set it has a 4' LED display and operates tfom a single -5Vpower supply The unit is provided complete with an miction molded blackpiastre case complete with Bezel An optional power supply is availablewhich fits into the same case as the 0-2V DVM allowing 117 VAC operation.

A. 0-2V DVM with Case $49.95

B. 5V Power Supply $14.95

VECTOR WIRING PENCIL

Vector Wiring Pencil PI 73 consists ol a hand held lealtWrwetgM i under one ounceltool which is used Id guide and wiap insulated wire led oM a sell-contained (BpfflCeaWetioDDm onta component leads 0' terminals installed on ore-punenea P PatternVijCtoraanj Connections Between the wiaonea wire ana noTtnoneni leads pads oiterminals are made try soldering Complete wiin 250 FT ol red wire en en

REPLACEMENT WIRE — BOBBINS FOR WIRING PENCILW36-3-A-Pkg 3 250 tt 35 AWG GREEN S2.40

W36-3-B-Pkg. 3 250 It 36 AWG RED S2.40

W36 3-C-Pkg 3 250 It 36 AWG CLEAR S2.40

W36-3-n-Pkg 3 250 It 36 AWG BLUE S2.40

1/16 VECTOR BOARD

6JPJJ 062*xxP'69PJ-02XXXP6JP4-: Ofi?

m

HEAT SINKS

205-CB

231-.36H680-.75A

u

Beryllium Copper Heal Sink with Black Finish loi TO-5

HEXADECIMAL ENCODER 19-KEY PAD

• ABCDE:

• Return Key

• Optional Key i Period)

• — Key

S10.95 each

63 KEY KEYBOARD

j', koylifiiiolealiiics 63 linen-:li:ilSPS1 keys lui.itiaciiedtoy kino or PC B Avery solidnaed oustic '3 > ■: baseits most amplications

$19.95

HDD165 IE LINE TO FOUR BIT PARALLEL KEYBOARD ENCODER

JOYSTICK

These joysticks feature four *potentiometers, lhat vary re-sistance proportional lo theangle of the stick. Sturdy metalconstruction with plasticscomponents only at the mova-ble joint. Perfect for electronicgames and instrumentation.

*5K Pots $6.95*100K Pots $7.95

MICROPROCESSOR COMPONENTS

821282148216

8224CDP1802

CPU

8 Bit Input/Output

Priority Interrupt Control

Bi-Duectionai Bus Driver

Clock Gcnerator/Ortvet

with user manual

CPUS

Super 6008Super 8008

i02.iD>r.am,r;He. 32 BitHe* 40 BIT512 DynamicI02J DynamicQuai 256 SiTDual 51? BITQuad SO BIT102-1 Static

F,ic

i Jflei;

S19.95 8228 System Contiollei - Bus Drivei S10.95

4.95 MC6800L 8 Bit MPU 35.00

15.95 MC5820L Penph. Interlace Adapter 15.00

6.95 MC6810AP1 128 x 8 Static RAM 6.00

10.95 MC6830L7 1024 x 8 Bit ROM 18.00

3995 Z80 CPU 49.95

StaticStaticDynamic

Stat'fSialic

StaticSiancStaticStan

SialicStaticDynamicPROMS

F.lllHV.

Famtw

2 496.956.95

25'33516

S 9.951095

1702A520362S2382S1J3

r-ts?ar3601

27ca

6301-16330-16331-1

Stain

M

Eprom

Tn-Stale Bipolar

Open Cnllccroi Bipolar

In-Stale Bipolai

3.9534 953 49

SPECIAL REQUESTED ITEMS

MC306IPMC4016P 0MC14583MC1-15G2

CDJ059CD4070

CD4508

CD4515

CD-I 520

UCM6571

MCM6574

MCM6575

35009 95

17 50

19 953.75

10 50

3341

936B

MC140BL7LD110/LD111AY-5-9100951(90

6.95

3 959 95

25.00/561

17 50 oa

1395

electronic 'PENDULUM' CLOCK

■ Unique Electronic Swing' Pendulum

■ Real Furniture Quality

■ Handicralted Unfinished Wood Case

■ Large .7" Hours, and Minutes LED Display

■ Alarm Feature

■ 12 or 24 HQur Mode

■ Time Set Push Buttons

■ Use Module For Easy Assembly

■ Special programed ROM in pendulumfor animated effect!

Dimensions ■ 10%" x 10' 2" x 3V4"

KIT —UNFINISHED* $59.95

ASSEMBLED — STAINED* $69.95

BUGBOOK R

Continuing Education Series

BUGBOOK 11II - Basic concepts olTTL Logic — over 90

experiments S17.00/set

BUGBOOK ll.i - Introduces UART — recommended

tor RTTY enthusiast S5.00/hook

BUGBOOK III - Explores 8080 chip — introduces

Mark 80 Microcomputer SI 5.DO. tjook555 TIMER APPLICATIONS SOURCEBOOK WITHEXPERIMENTS —over 100 design techniques S6.95/bookCMOS-M-OESIGNERS PRIMER AND HANDBOOKa complete CMOS instruction manual S6.00

Introductory Otter — all 6 hooks (worth $49 951SPECIAL ■ S42.95

CONTINENTAL SPECIALTIES

PROTO BOARD 6$15.95

(6" long X A" wide]

Other CS Proto Boards

PROTO CLIPS

14 PIN S4.50

16 PIN 4.75

24 PIN 8_50

DESIGN MATES '

I - Circuit Designer

54.95I - Function Generator

69.95i - RC Bridge

59.95

QT PROTO STRIPS

•fWhi'Wi:'•tttt&fil-

QT typeQT-59SQ1-59BOT--I7S0T-47BOT-35SQT-35BOT-18SQT-I2SQT-8SOT-7S

price12 502 5010 00

Experimenter 300Experimenter 600

$ 9.95S10.S5

S5.00 Minimum Order — U.S. Funds OnlyCalifornia Residents — Add 6% Sales Tax

Spec Sheets - 25c — Send 35t* Stamp for 1977A CatalogDealer Discount Available — Request Pricing

1021-A HOWARD AVE., SAN CARLOS. CA. 94070PHONE ORDERS WELCOME — (415} 592-8097

All Advertised Prices Good Thru May

u»*

tfitt*

PARATRONICS >

LOGIC ANALYZER KIT

■n m fen Popiilai Eleciiomcs

Troubleshoot anytype of digitalsystem includingMicrocomputers.

LA100 KIT S189.0Q

DIGITAL AUTO INSTRUMENT

SEVEN DIFFERENT INSTRUMENTS!

MEETS OR EXCEEDS ORIGINAL AUTOMOTIVE SPECS.

Please specify which one of the seven models you want

when ordering - these do not all come in one unit

Each model must Oc bough! separately

4 TACHOMETER 4?SErS&METER*

1 0-9900 RPM■i 6 or 6 Cyclindei

FUEL LEVEL3 Percentage

Low Fuel indi

BRIGHT YELLOW ORANGE.3" LED DISPLAY!

includes case, bracket and nil comi>one!s — completeNothing else to buy 12 Volt NEG GRDDIMENSIONS 4'.-»4ijAda S'O OO idi required speed t

KIT: S49.95ASSEMBLED: S59.95

DIGITAL STOPWATCH

■ Bright 6 Digit LED Display

. Tunes id 59 minutes 59 59 SKCflffl

• Crystal Controlled Time Base

• Three Stoowatcbes m One

Times Single Event — Split & Taylor

• Size4 5 X2.15 x 90 i4'jouncesi

• Uses 3 Penhie Cells

Kit - S39.95

Assembled — S49.95

Heavy Duty Carry Case S5.95

Stop Watch Chip Only (7205) S19.95

(D Tirneband

DIGITAL ALARM CLOCK $16.95

• 24-Hour Alarm

• "DOZE" Button. 100% Solid State

• Large Red Led Display (.8" high)

• AM/PM Indicator

• Seconds Dispiay at touch ol button \

• SPECIFY BLACK OR IVORY V

QUARTZ DIGITAL AUTO CLOCKOR ELAPSED TIMER!

Elapsed Timer: Hrs, Mins and Sees

12 or 24 Hi Capacity

Simple Reset - Start Pushbutton

Control

Complete kit includes mountinrj biaeket.

case and all components not hint) Use lo

tiny rea1uiesMM531Jcri'f] Large 4 LED s

Accuracy (letter man 2 min per mo internal

Tattery backng. 12 .all noiw.oisi opfalion

Kit: S29.95Assembled: S39.95

CASE ONLY (includes hardware, mounting bracket and Ouzel) S6.50

JE700 CLOCK

Tne JE TOO is a tow cost digital clock outis a very riign quality unit trie unit te.ilures a simulate!] walnut case wiin 01rnensions ol 6 i2'.- il It ulilizes aMAN73 iitgn bngtWess nuaout ana tneMMS3U dock Ghnj

$17.95

DIGITAL CLOCK KIT — 3Vz INCH DIGITS

4 DIGIT KIT 549.95 4 DIGIT ASSEMBLED S59.95

6 DIGIT KIT S69.95 6 DIGIT ASSEMBLED S79.95

This clock features big 3V;" high rjigits for viewing in offices, auditoriums,etc. Each digit is formed by 31 bright 0.2" LED's. The clock operates from117 VAC, has either 12 or 24 hr. operation. The 6 digit version is 27" xVh" Ki%" and the 4 digil is 18" x V/2" x 1V Kits come complete withall components, case and transformer.

Specify 12 or 24 Hour When Ordering

JE803 PROBE

K"»J

I tie Loqic F'ffiJif is a jnil wructi is lor TTie TiOSI parindeswnsibte in trouble shooting logic MmiksITL OTL RTL CMOS ll derives tne power iliceds lo operate directly o'l ol the cncmi underest drawing a scant 10 ml max HusesaMAN]eartout to mdrcate any ol the tallowing States by

tiese symbols iHl-l iLOWt n| PULSE' P rtM *n ft- rj_„ i/;aPrOOSCandetecihignlreauencypulsestD't5MH: H>y.yO rcT MI

nt rj

: '.105 ■■•

■ !.!'

printed circuit board

PL 5V 1A Supply

This is a sraruflri TTL power supply using Hie well knownLM309K legu-iior if, to provide a sniio 1 AMP nl cui rem ai 5volls We iry lo make things easy (or you by provirnnq

fivrriYtnmgymi'ined in niiniMCiiaiii! hicIiiiIiih; iiih liiitilw.in:

**"* S9.95 Per Kit J

7400NTTU

SN7400N

5N7401NSU7402NSN7403NSN7404NSN7405NSN/406NSN7407\SN7406NSN7409NSN7410NSN7411NSN7412NSN7413N5N7414NSN7416NSN7417NSN7420NSN7421NSN7422NSN7423NSN7425NSN7426NSN7427H5N7429NSN7430NSN7432NSN7437NSN7438NSN7439NSN7440NSN7441NSN7442NSN74J3NSN7444NSN7445NSN7446NSN7447NSN7448NSN7450NSN7451NSN7453NSN74S4N

SM7459A

SN7460N

SN7470N

SN7472N

SH7473N

SN7474N

SN7475N

SN7476N'

SN7479N

SN7480N

SN7482N

SN74B3N

SN7485N

SN74B6N

SN74B8W

SN7489N

SN7490N

SN7491N

SN7492N

SN7493N

SN7494N

SN7495N

SN7496N

SN7497N

SN74100fJ

SN74107N

SN74121N'

SN74122M

SN74123N

SN74125N

SN7412EN

SN74132N

5N74136N

SN74141N

SNM142N

SN74143N

SN74144W

SN74145N

SN74147N

SN74148N

SN74150M

SN74151N

SN74153N

.25

3.50

SN74154NSH74155NSN74156NSN74157NSN74I60NSN74161NSN74163NSN74164NSN74165NSN74166NSN74167NSN74170NSN74172NSN74173NSN74174NSM74175NSN74176NSN74177NSN741BONSN74181NSN74182NSN74184NSN74185NSN741B6NSN74187NSN741BBNSN7419DNSN74191NSN74192NSN74193NSN74194NSN74195NSN74196NSN74197NSN74198NSN74199N5N74200NSN74279NSN74251NSN74284NSN742B5NSN74367N

MANY OTHERS AVAILABLE ON REQUEST20% Discount lor 100 Combined 7400's

CD4000CD4001CD4C02CD4CD6CD4007CD4009CD4010C04011CD4012CD-013CO4016C04017CD4019CD4D20CD4022CD4023CD4024CD4Q25CD4027CD4028CD4029CD40jO

.25

mm—

LM301H

LM301CN

LM302H

LM304H

LM305H

LM307CN

LM308H

LM308CN

LM3Q9H

IM309K

LM310CN

LM311H

LM311N

LM31BCN

LM319N

LM320K-5

LM320K-5.2

LM320K-12

LM320K-15

LM32QT-5

LM32QT-5.2

LM320T-8

LM320T-12

LM320T-15

LM320T-18

LM320T-24

LM323K-5

LM324N

LM339N

LM340K-5

LM340K-6

LM340K-B

LM340K-12

LM34DK-I5

LM340K-1B

LM340K-24

LM340T-5

LM340T-6

LM340T-B

LM34GT-12

LM340T-15

LM340M8

LH340T-24

LM350N

LM351CN

CMOS

CD4035 1 65

CD4040 245

CD40J2 190

CD4Q44 1.50

CD4046 2.5!

CD4047 2 75

CD4049 79

CD405D 79

CD4051 2.95

C04053 2 95

C04060 3.25

CD4066 1 75

CD4069 45

CD4071 45

CD4081 -15

C04B11 2.50

CD4518 2 50

MC14566 3 00

74C00N 39

74C02N 55

74C04N74C10N

74C20N

74C30N

74C42N

7JC73N

74C74

74C90N

74C95N

74C107N

-4C151

74C154

74C1S7

74C160

74C161

74C163

74C16-I

74C173

74C193

74C195

MCJ044

MCI 4016

LINEAR

LM370N

LM373N

LM377N

LM380N

IM380CN

LM381M

LM3B2N

NE501K

NE510A

NE531H

NE536T

NE540L

NE550N

NE555V

NE560B

NE561B

NE562B

NE565H

WE565M

NE566CM

ME567H

NE567V

LM703CN

LM709H

LM709N

LM710N

LM711N

LM723H

LM723H

LM733N

LM739N

LM741CH

LM741CN

LM741-14N

LM747H

LM747N

LM748H

LM748N

LM1303N

LM13Q4N

LM1305N

LM1307N

LM1310N

74LS0074LS0?7-1LSG374LS0474LS0574LS0S?4LS«074LS1374LS1474LS2074LS2674LS2774L52B74LS3074LS3274LS4074LS5174LS55

5 74LS00 TTL't

LMI351N 1 6

LMI414N 17

LM1458C 6

LMI496N 9

LM1556V 1 B

LM2M1N 1.9

LM2901N 29

LM3065N 6

LM39Q0N .5

LM3905N 6

LM3909 1.2

LM5556N 1.8

MC555BV 1 0

LM7525N 9

LM7535N 1 2

B038B 4 9

LM75450 A

75451CN .3

75452CN .3

75453CN 3

75454CN 3

75491CN .1

75492CN .B

75494CN 8

RCA LINEAR

CA3013 2 1

CA3023 2.5

CA3035 2.4

CA3039 1.3

CA3046 1 3

CA3059 3!

CA3060 3 2

CA3060 E

CA30B1 2.C

CA3Q82 2.C

CA30B3 1 E

CA30B6 i

CA3089 3.;

CA3091 10;

CA3102 2 i

CA3123 2 1

CA3130 i :

CA3140 1.1

CA3600 1 /

RC4194 B.(

RC4195 3.1

/■i LS18

74LS75

7JLS7f,

74LS83

r4lS83

7JLS86

741S90

74LS92

74LS93

7JL595

74LS96

74LS107

MLSllH

74LSH?

74LS132

74LS13B

MLS 15374 LSI 57"JL516274LS163■*JLS16474LSI7&74LS1B174LS1907JLSI9'741519274 LSI 9374LS1P474LS19574LS25774LS2607JLS27974LS670

MM5309MM5311MM5312MM53KMM5316MM5318CT7001

CLOCK CHIPS

6 Oigi! BCD Outputs Reset PIN

6 Otgn BCD Outputs 12 Di 24 Hour

4 Digit BCD Outputs t PPS Output

6 0igi1. 12 oi 24 Hour 50 or 60 Hj

4 Digit, Alarm. 1 PPS Output

Video Clock Chip. For Use With IMM5841

G Diqil. Calendar. Maim 12 or 24 Hour

DATA HANDBOOKS

Pin-out & Description of 5400 7400 ICS

; Pin-oui Ki DuserifMion of 4000 Sunos ICS

■ Pin our & r-uiiclion.il Description

ALL THREE HANDBOOKS S6.35

S2.95S2.95S2.95

There is only one

nssimm

They can try and copy our ad,

BUTThey can't copy our service!

XC209XC209XC209XC209

XC22XC22XC22XC22SSL-22

GreenOrange

DISCRETE LEDS

XC526

Red

XC526

Green

XC526

Yellow

XC526

Orange

XC526

Clear

XC556XC556XC556XC556

XC556

GreenYellowOrangeClear

Orange 4.51

.085" dla.MV50 - Red ■ 6 Si

SPECIAL * — XC556 Red 100/S8.00 1000/S60.00 — SPECIAL *

DISPLAY LEDS

HT TYPE POLARITY

270 2 95 MAN 3640 Common Caihorje-oiange

30D 4 95 MAN 4710 Common Anode-Red

125 3 1 00 DL701 Common Anode-red x

1B7 1 95 0L704 Common Cat ft Ode

.300 1 25 DL707 Common Anode

300 1 95 MAN 4740 Common Anode-Red

300 1 95 DL741 Common Anode

300 99 dl 747 Common Anode

400 99 DL 750 Common Ciitiout;

300 1.50 DL 33B Common CaiHorjrj

300 99 FND70 Common Caihodo

3011 99 FND5D3 Common Cathode

300 1 75 FND507 Common AnorJe

MAN 1

Common Anode

MAN 2

5 . 7 Dot Matrix

MAN 3

Common Ca'.hoae

MAN 4

Common Cam ode

MAN7

Common Anode

MAN 7G

Common Anode -gieen

MAN 7Y

Common Anoae-vciiow

MAN 52

Common Anode-green

MAN G4

Common Anode-ren

MAN 74

Common CaifiOde

MAW 82

Common Anode-yBltow

MAN B4

Common Cainode-ytilin

MAM 3620

Commnn Anoae -orang

«Sc°i"s ATARI GAME BOARDS

BOARD A— B'i > 16

Over G0ear.li reusaoie ICsMisc Transuto's ResistorsOrodes. Caps. Crystals. Swucn etc

DELUXE BOARD B— IW*

Ovei 100 each itiiisable ICsMisc Trnnisiors. ResistorsDiodes Caps. Crystals. Switcfios LEDS

S6.95 ea.

ONLY 500 EAAVAILABLE

S3.95 ea.

ONLY 500 EAAVAILABLE

NEW AY-3-8500-1 TV GAME CHIP

■■•" ■■)

1 Selectable anglesspeed and bat sue

> Auto o> manual oali service

■ Realism sounds

. 6 Games —tennis. Iiockcy;ioccei sguasn. pulola'[itacuce and two ntle games

28 Lead DThe circuit is intended to he Datteiypowered Minimum numCei orexternal components requiredtor complete system

$24.95

IC SOLDERTAIL— LOW PROFILE (TIN) SOCKETS25-49 50- ""

)8 pin22 pin

16 pinIB pm

24 pin

16 pinM pin

15 SOLDERTAIL STANDARD (TIN)

SOLDERTAIL STANDARD (GOLD)

24 pin28 pin36 pin40 pm

WIRE WRAP SOCKETS (GOLD) LEVEL #3

WIRE WRAP CENTER ^

HOBBY-WRAP TOOL-BW-630

Battery Operated (Size C)Weighs ONLY 11 OuncesWraps 30 AWG Wire pntoStandard DIP Sockets (.025 inch)«. Complete with built-in hit and sleeve

$34.95

(Catteries not 'ncluoedi

WIRE-WRAP KIT — WK-2-WWRAP . STRIP . UNWRAP

• Tool lor 30 AWG Wire

• Roll ol 50 Ft. White or Blue 30 AWG Wire

• 50 pes each 1". 2". 3" & 4" lengthspre-stripped wire.

$11.95

i). Plastic Push Button Switch

-18 AWG Solid Wire - 5" Long' .SO (wide) X .60 (high) >.-27 Tlironil• 8 AMP @ 14 Volt - 1 AMP (i . 10 Volt1-9 10-UpJ-IB8-1 Push On-Push Oil 59 4938-2 Normally Open 59 49

3B-3 Normally ClosM 59 49

i

■ CLIPLITE 8/S1.49

LED MOUNTING SYSTEMuse with XC556 LEDS

IV1INATURE TOGGLE SWITCH

JMT-221 DPDT on/oft/on SI.95

JMT-223 DPDT on/none/on S1.75

JMT-121 SPDT on/off/on S1.50

JMT-123 SPDT onlnone.on S1.25

I

DIP SWITCHES

SPST Slide Action

SI.75 ea.

S1.95 ea.S2.25 ea.

50 PCS. RESISTOR ASSORTMENTS $1.75 PER ASST.

ASST. 1ASST. 2ASST. 3ASST. -5ASST. 5ASST. 6ASST. 7

10 OHM 12 OHM

27 OHM 33 OHM

66 OHM 8? OHM

ISO OHM 220 DHM

470 OHM 560 OHM

1 ?K

1 5K

15 OHM 18 OHM

39 OHM 47 OHM

100 OHM 170OHM

270 OHM HO OHM

U"80 OHM B20 OHM

220K560K

120K330KH?OK

1/4 WATT 5"„ 50 PCS

l/J WATT 5°o 50 PCS.

1/4 WATT 5% 50 PCS.

1/4 WATT 5"= 50 PCS.

1/4 WATT 5"= 50 PCS.

1/4 WATT 5% 50 PCS.

1/4 WATT 5°= 50PCS.

ASST. 8R lncludesResistQrAssortments1-7(350PCS.) §10-95 ea.

S5.U0 Minimum Order — U.S. Funds OnlyCalifornia Residents — Add 6% Sales Tax

Spec Sheels - 2&V — Send 35i' Stamp lor 1977A CatalogDealer Discount Available — Request Pricing

1021-A HOWARD AVE.. SAN CARLOS. CA. 94070

PHONE ORDERS WELCOME — (415) 592-8097

All Advertised Prices Good Thru May

WIRE WRAP TOOL WSU-30WRAP • STRIP . UNWRAP-J5.95

WIRE WRAP WIRE — 30 AWG

25tt.min.S1.25 50lt.S1.95 100ft.S2.95 1000ft S15.00SPECIFY COLOR — White - Yellow - Red - Green - Blue - Black

CUTTER CRIMPER TOOL (CS-8)

• Pher Nose (serrated-jaw)

• Scissors Action Cutting

. 6 Bolt Cutters (4-40. 5-40, 6-32, 8-32,10-32. 10-24)

• Crimp Stations (7mm Auto — 22-20 to12-XO elect.)

• "Up-Front" Wire Cutting

• Scissors Action Stripping (No. 22-20 to No, 10)

• Crimp Stations — insulated (2w-20 to12-10 elect.) CQ _-

Actual Size - 6% length !j>0. OU

Permacel Electrical Tape

3/j"(wtde)X66tt (long) • AM weather • NolimportS1.25 per roll — S9.95 per 10 roll package

nPE

1N7461N751A1N7521N7531N7541N959IN965B1N52321N523J1N52351)02381N4561N45SIN485A1M-1001I (M0021N40031N40Q.1

ZENERS —

VOLTS W

400m400m400m400m400m500m500m500m500m

50 P1V 1 AMP

100 PIV 1 AMP

200 PIV 1 AMP

400 PIV 1 AMP

DIODES —

PRICE TYPE

4 1 00 1N4005

4 t 00 1N4Q06

4,1 00 1N4007

4,1 00 1N360O

J 1 00 1N4148

8 1 00 1N4154

4 1 00 IN4305

28 1N4734

28 IN4735

28 1N4736

28 1N4738

6 1 00 1N4742

6 1 00 IN47-I4

6. TOO IN1183

12.100 1N11B4

12 1 00 1N11B5

12 1 00 IN1186

12 1 00 INI IBS

RECTIFIERS

VOLTS W600 PIV 1 AMP800 PIV 1 AMP

1000 PIV 1 AMP200m

PRICE

10 1 0010 1 00

10m10m

12

15 1*

50 PIV 35 AMP

100 PIV 35 AMP

150 PIV 35 AMP

200 PIV 35 AMP

400 PIV 35 AMP

SCR AND FW BRIDGE RECTIFIERS

C36D I5A @ 400V SCR

C38M 35A @ 2O0V SCR

2N232B 1 6A @ 200V SCR

MDA 980-1 12A @ 50V FW BRIDGE REC

MDA 980-3 12A @ 200V FW BRIDGE REC

MPS A05

mps m

2IJ2!I9A2N2231

3N23692IJ2369A2N24BJ2N2996A2N29U7A2N29252f;30532N30SSMJE30S5MJE)3i52N3.1922N339Q

3ST K)

5.ST CO3S1 00

5 SI COi St DO4 st ogJ St 00

TRANSISTORS

PN3567 3 S! 00

PN356B 4S1 00

PN356H J.'SI 00

2N3701 5 St 00

2N3705 5S1 00 M

!N3706 SSI 00 J

2N370r SSI 00

2N37H iSl 00

2N372J S 65

2N3725 SI 00

2N3903 5 Si DO

2N390A J SI CO

2N3905 i Si 00

2N3936 4 St DC

2N4013 SSrOO

2N4J00

2NW01

IN4.10!

2K4403

2N44Q9

2NS0SB

2N508:

2N50Ba

2NMS9

2N5'29

2-15138

2N5139

2N5209

2N5951

ClOfiBISCfi

2N5-I32

?S1O05 Si 005 Si 00

CAPACITOR

50 VOLT CERAMICOISC CAPACITORS

10-49 50-100

04 .03 .OOVF

CORNER

10-49 50-100

100 pi220 pt470 pi

001ml.0022.0047ml,01ml

1.35V15.35V.22/35V.33>35V47/35V68 35V1 0 35V

.05 04 03 004/ijF OS CM

.05 04 03 01/iF 05 04

.05 .04 03 ,022,-F 06 .05

.05 04 .03 .047^-F 06 05

05 04 035 VF 12 09100 VOLT MYLAR FILM CAPACITORS

12 10 .07 022ml 13 tl

12 10 07 047ml 21 17

.12 10 .07 1ml 27 23

.12 10 .07 .22mf .33 27+ 20% DIPPED TANTALUMS (SOLID] CAPACITORS

.28 23 17 1 5'35V 30 26

28 23 17 2.2 25V 31 27

.28 23 17 3.325V 31 .27

.28 23 17 4.7/25V .32 28

-28 23 17 6.8/2SV 36 .31

28 23 17 10 25V 40 35

,28 23 17 15 25V 63 50

MINIATURE ALUMINUM ELECTROLYTIC CAPACITORS

47/50V1 0/50V

3 3j50V

4 7,25V10/25V10/50V22/25V22.50V47/25V47.50V

l00f25V100/50V220/25V220:50V470,25 V1000'16V2200'16V

Axial Lead

10

.47/25V

47/50V

1.0.-16V

t 0.25V

1.0/5QV4.7/16V4 7/25V4 7.50V10/16V1025VI050V47/50V100/16V100 25V100.50V220,'16V470/25V

Radial Lead

.15

13

computer display terminal

This display terminal has an integral controller, B/W cathode ray tube and keyboard. The system has a serial I/O interfacefor communication and an I/O interface for a printer

DISPLAY (P/N 4802-1095-501) FEATURES:

• 17" B/W CRT

• 41 lines of data

• 52 characters per line

• Characters are generated by a diode matrix "graphic"technique

• 21 special push-buttons wired for a program call up

• Brightness Control

• Self-contained power supply

KEYBOARD (P/N 4802-1115-501) FEATURES:

• Reed switch technology

• 54 data keys

• 28 special keys detachable with cable

LOGIC UNIT (P/N 4802-1157-502) FEATURES:

• 1024 by 6 bit core memory

• Printer I/O interface

• Communication I/O interface

POWER: 115V, 50/60 Hz, 500 Watts

WEIGHT: 210 lbs. (including logic unit, keyboard,display and cables.)

FOB LYNN MASS (you pay shipping)Check with order please.

$180.00

External logic & power pack not shown.

AS IS

55

4 way cursor control, graphics display.

The story: These are unused terminals made for airportticketing & seat assignment. After several years ofstorage they require tinkering to make operable. We havesome hints printed such as cleaning PC fingers. One ofour customers has this tied into his KIM-1, another hashis running with his IMSAI. We have data on this.Should be useable on most common computers. A hellof a deal and all for a paltry $180.00. Don't be left outas many were on our past VIATRON deal. Sold "as is"all sales final.

WITH COMPLETE DOCUMENTATION

c;ir~?~- '•"■■-■ tTMTTM u^jjs.' <i:.;-mb> a

si

uggro WZ

Here is a real deal in a PC module 6x5 sockets (30). Listprice over $50 each, most by AUGAT. Some pre-wired.New, unused boxed, 14 or 16 pin, 5x6 sockets. $15.00each or 2 for $25, state your choice 14 or 16 pin.

IC Sockets, while they last. . .8 Pin 10/$1.00

14 Pin 10/$1.25

16 Pin 10/$1.50

18 Pin 10/$1.75

14 Pin IC connector 10/$1.25

sfie&hMci

WIRE WRAP GUNS

Used wire wrap guns, released dueto factory closure. Various mfgrs,some Ingersol Rand, electric or air.

No collets. State choice.

Cost over $100.00 each

Our price only $15.00 each.

shown actual size

SOLAR CELLS

Designed for the space program, these are the highlyefficient silicon high output cells. Used for poweringequipment, charging batteries. Made by Ion PhysicsCorp. Each with spec sheet.Size .394 x .788" 65 mA, .43 V $1.25 12/$12.00Size .788 x .788" 125 mA, .43 V $1.60 12/$15.00

Please add shipping cost on above. Minimum order $10

FREE CA TALOG SP-9 NOW READYP.O. Box 62, E. Lynn, Massachusetts 01904

A

ADD CALCULATOR FUNCTIONS without adding

more

-^

"7

;

I '

memory to your micro.

The R.G.S. malhmatical function

unit ■

1

uses a calculator chip to

provide floating pc

int add,

sub, mult, |

divide.

og, trig

& power

functions for your

micro.

0*

PC BOARD AND MANL

IAL

S27.00

,,..;':::::': *•"

- r WWCWTpWHCS

---**--*«"-*•...

'- ^_ » ' ' -

HEAVYDUTY

TOP QUALITY

$28

5VDC@ 22A

- -iLlB*''

- ". '

* *„

i$7

• a

*r

POWER

wk

f T**"

TRANSFORMER

#18 VDC

••Vta

|^

FOR

\ &

40V

pcoJ

no

IMSAI/ALTAIR

(Prom programming)!

•eHectrc

nics

INCLUDE APPROX SHIPPING

LIMITED QUANTITY

20 LBS

'

J

the proko

3££££ZS£i* electronics shoppe

positive & negative strobe outputs.

Tlii: nosve

i'5V 1 20

■tal

tax. All ardors positin Ihe U.Q <:in ut"

aid

4jy marsh

St.

1 THE PROKO PAPER TAPE READER: A lully TTL bu«erw

is derived from yout 10 board.., Jusl supply

liqlll soilici

order. Pr

ces subjfici

10 san luis obispo, ca.

93401

■ ■ ■

li.ilier tape It's

(siuily tamp), grab the tape .mil pull!

change w

:o.

805/544-5441

' "hl'->v"h nmrlY ■ i''111,1 '"I

hi [ions and has boih

PTR ■ II KIT S54.00

ASSEMBLED S6B.

* JUST IN:

|

L___

kits by [©] cubercDm

k^J Dujiv,:.,,i,,.| SCLIIISIATI MUSIC

*

4 J

64 X 16 VIDEO BOARD Alta

r plug compatible display

2102AL-4 • FULL SPEED MEMORY (500ns)

4Kx8 Static Memories

32 x 16 or 64 x 16 switch selectable

Composite and

*

*64

Slearly 1/3 less power consumption

of even a21L02A

2.00 EACH 32 FOR 1.80 EACH

* 1

* 1

MB-1 MK-8 board, 1 usee 2102 or eq. PC Board $22 |(NOT FOR S-100 BUSS) |

MB-2 Altair 8800 or IMSAI compatible Switched address

parallel video ports, upper and lower case with software.

Kit $179.95

PC board S35

SP-1 Synthesizer board. Computer controlecl wave

- 1.70

128 FOR 1.60 EACH

and wait cycles. PC Board $25MB-4 Improved MB-2 designed for

forms 9 octaves 1 vrms '/..% distortion includes high

8K "piggy-back" |

language.

82S06

2.00

82S126

3.50

74C200

5.50

without cut

ing traces. PC Board

KIT

$250.

82S07

2.00

82S129

3.50

8573

4.50

Kit 4K .5

usee... $129.95 Kit 8K

.5 usee $199 I

Altair compatable mother board. Room for 15

Donnec-

82S11

2.00

82S130

3.95

8574

5.50

tors 11" x 11W (w/o connectors)

$45

82S12

2.00

82S131

3.95

8575

4.50

MB-3 1702A's Eroms, Altair 8800 & Imsai 8080 compat- |

With 15 connectors $110.00

82S17

2.00

74S206

2.10

8576

4.50

ible Switched address & wait cycles

2K may be ex-.

82S23

2.50

74S412

4.00

8577

3.50

panded to

4K. Kit less Proms $65 2K Kit S145!

Altair extender board (w/o connectors) $9.50

82S123 3.00

8578

4.00

4K Kit $225

With w/w connector $13.50

100 Pin spec WW or Soldertail both

it IMSAI

or SSM

74007401

.1616

74737474

.35.35

7416474165

1.101.10

MB-6 PC Btl

MB-6A8Kx8 Switched address and

S35

wait assignments!

Mother Bd $5.00 ea 10/$44

7402

.21

7475

50

74166

1 25

7403

16

7476

.30

74170

2 10

Memory protection is switchable for 256, 512, 1K, 2K, 4K 1

1702A'EROM

S10.00

7404

.18

7480

.50

74173

1 50

and 8K. 91L02A .5 usee rams, Alta

r 8800 & IMSAI 1

■programming send hex list

5.00

7405

.24

7483

.70

74174

1.95

compatible

With battery power option

AY5-1013UART

$6.95

7406

20

7485

.90

74175

95

Kit $250

Assembled & tested

5290 1

2513 prime spec, upper or

7407

.29

7486

.40

74176

.90

I/O Boards

lowercase

11.00

740874097410741174137414

.25.25.1830.45.70

748974907491749274937494

2.00.45

75.50

50.80

741777417974180741817418274184

.90

90

90

2.50

.951.95

T/0-2 1/0 for 8800, 2 ports, committedother pads for EROMS UART, etc.Kit $47.50 PC Board only

pads for 3 more, 1$25

8080A prime CPU8212primelatch buffer8224 prime clock gen8228 prime sys controller

25.004.005.008.90

7416

.35

7495

.75

74185

2.20

MM5309

8.00 2501B $1.25

1101 1.25

74LS00 .40 74L00

.25

74L78

.90

7417

.35

7496

.90

74190

1.15

MM5312

4.00 2503V 2.00

1103 1.25

74LS01 .50 74L01

.25

74L85

1.40

7420

20

74100

1.00

74191

1 25

MM5313

4.00 2504V 2.00

2101 4.50

74LS02 .40 74L02

.25

74L86

.75

7423

.37

74107

40

74192

90

MM5320

4.95 2505K 2.00

2111-1 4.50

74LS03 .40 74L03

.25

74L89

3.50

7425

30

74109

.90

74193

.90

MM5554

1.90 2507V 1.25

2112 4.50

74LS04 .45 74L04

.30

74L90

1.50

7426

30

74121

40

74194

1.25

MM5556

2.50 2509A 2.00

2602 1.60

74LS05 .45 74L05

.40

74L91

1.50

742774307432

35.25

30

741227412374125

.50.70.60

741957419674197

.751 25

.90

1 MM5055DM8836

1.90 2510A 2.00.60 2511A 2.80

4002-1 7.504002-2 7 50

74LS10 .40 74L0674LS11 .50 74L08

.30

.40

74L9374L95

1.701.70

7437

.27

74126

.60

74198

1.75

DM8837

1.50 2517V 1.25

MM5262 1 00

74LS12 .55 74L09

.40

74L98

2.80

7438

27

74132

1 00

74199

1.75

80C95

1.10 2518B 1.50

7489 2.00

74LS20 .40 74L10

.30

74L123

1.50

7440

.15

74141

1 15

74200

4.95

80C97

1.00 2519B 2.80

74200 4.95

74LS22 .45 74L20

.35

74L154

2.00

7441

.85

74145

1.15

74251

1.75

| 80L97

1.50 2521V 1.50

74S89 3.50

74LS27 .45 74L26

.40

74L164

2.50

7442

60

74147

2.35

74284

4 95

1 81L22

1.50 2522V 2.00

74C89 3 50

74LS30 .40 74L30

.40

74L165

2.50

7443

75

74148

2.00

74285

495

81L23

1.90 2525V 2.80

74L89 3.50

74LS42 1.50 74L32

.45

74L192

1.25

7444

.75

74150

1.00

74365

90

85L51

2.50 2527V 2.80

8223 2.50

74LS55 .40 74L42

1.50

74L193

1.20

7445

.75

74151

80

74367

.75

85L52

2.50 2528V 2.80

8T80 2.50

74LS73 .65 74L51

.35

MC4044

2.25

7446

80

74153

90

74368

90

85L63

1.25 2529V 2.80

8T97 2.00

74LS74 .65 74L54

.45

N8263

3.50

744774487450

7080.25

741547415574156

1.001 001 00

MH0025MH002695H90

2 502 959.95

86L701 86L75

1.50 2532B 2.801.90 2533V 2.80

INTEL8216 4.95

74LS76 .65 74L5574LS151 1.55 74L71

.35.30

N8826DM8131

2.502.50

7451

.25

74157

1 00

1 86L99

3.50 91L02APC 2.55

8214 8.30

74LS174 2.20 74L73

.55

8T16

2.00

7453

25

74160

1 25

1 86L12

.80 32 each 2.40

8251 14.5C

74LS175 1.95 74L74

.55

8T20

2.00

7454

.20

74161

1 00

I8T13

2.50 64 each 2.25

8255 14.5C

74LS192 2.85 74L75

1.20

8T10

2.00

74607470

7472

.20.45.40

7416274163

1 501 00

14881489

1.501.50

For large orders please send money order c

r cash-

MIKOS

iers check to avoid delays in waiting for checks to

:50 Day Guarantee on SSM Products. Kits MB-2. MB-3

Check or money order only. Calif

resident 6%tax.

|2K OR

4K), MB-4. MB-6,

10-2 video board an

j mother

419 Portofino Dr.

All orders postpaid in U.S. All devices tested

prior to

board v,10% in

ith connectors may be cornbiquantities of 10or more. This

ned for a discount ofsupercedes the flier

San Carlos, Ca. 94070

sale. Money back 30 day guarantee. Sorry we can 1not accept returned IC's that have been soldered to. 1

of 13 Sept. 1976.

Please send for xistor. IC

& kit list

S10 min. order. Pricesnotice.

subject

o change

without I

Thinly disguised affiliates of KO Electronics and Surplus, S.L.O., CA 93401

S.D. SALES CO. pO. BOX 28810-Q DALLAS, TEXAS 75228

JUMBO LED CAR CLOCK

Alarm OptionACXFMR -

-$1.50$1.50

THE HOTTEST SELLING KIT WE EVER PRODUCED!

You requested it! Our first D.C. operated clock kit. Professionallyengineered from scratch. Not a makeshift kluge as sold by others.Features:

A. Bowmar Jumbo—.5 inch LED array. r\Jd^^r

B. MOSTEK - 50250 - Super Clock Chip. „.xClf \^^°

C. On board precision crystal time base. ^qO S'

D. 12 or 24 Hr. Real Time Format.

E. Perfect for cars, boats, vans, etc.

F. P.C. Board and all parts (less case) included.

«rV,o

THIS MONTH'S SPECIALSAMD - 8080A $14.95

Z-80 CPU 49.95

82S129 1KPROM 2.50

60 HZ CRYSTAL TIME BASES.D. SALES EXCLUSIVE!

$5.95 ea.

.00

1702A 2K EPROM

We tell it like it is. We could have saidthese were factory new, but here is thestraight scoop. We bought a load ofnew computer gear that containeda quantity of 1702 A's in sockets. Wecarefully removed the parts, verifiedtheir quality, and are offering themon one heck of a deal. First come,first served. Satisfaction guaranteed!U.V. Eraseable. $695 ea 4/$25

2,$A0.<

KIT FEATURES:

A. 60HZ output with accuracy comparable to a digi-tal watch.

B. Directly interfaces with all MOS clock chips.

C. Super low power consumption (1.5 MA typ.)

D. Uses latest MOS 17 stage divider IC.

E. Eliminates forever the problem of AC line glitches.

F. Perfect for cars, boats, campers, or even for port-able clocks at ham field days.

G. Small size; can be used in existing enclosures.Kit includes Crystal, Driver IC, PC board, plus all necessaryparts and specs. At last count — over 20,000 sold!

UP YOUR COMPUTER!21 L02-1 1 K LOW POWER 500 NSSTATIC RAM Time is of the essence!

And so is power. Not only are ourRAM's faster than a speeding bulletbut they are now very low power.We are pleased to offer prime new21L02—1 low power and super fastRAM's. Allows you to STRETCHyour power supply farther and at thesame time keep the wait light off.8 for $12.95

d-ionr- S.D. SALES EXCLUSIVE

$1^.95 MOS 6 DIGIT UP-DOWN COUNTER $12.95

40 PIN DIP. Everything you ever wanted in a counter chip.Features: Direct LED segment drive, single power supply (12VDC TYPE.), six decades up/down, pre-loadable counter,separate pre-loadable compare register with compare out-put, BCD and seven segment outputs, internal scan oscilla-tor, CMOS compatible, leading zero blanking. 1MHZ. countinput frequency. Very limited quantity! WITH DATA SHEET

I

1000 MFDFilter Caps

Rated 35 WVDCUpright style

with PC leads.Most popularvalue for hobby-ists. Compare atup to $1.19 ea.from franchisetype electronicparts stores. S.D.Special 4/$l.

Slide SwitchAssortment

Our best seller.Includes mini-ature and stan-dard sizes; sin-gle and multi-position units.All new, firstname brand. Tryone package andyou'll reordermore! Special12/$ 1.00

RESISTORASSORTMENT

>AW 5% & 10%

PC leads. A good

mix of values.

200/$2.

7400—19c 7411—29c74LS00—49c 7413—50c7402—19c 7416—69c74LS02—49c 7420—19c

7404—19c74L04—29c74S04—44c74LS04-49C7406—29c7408—19c7410—19c

7430—19c7432—34c7437—39c7438—39c7440— 19c7447—85c7448—85c

7451-7453-7473-7474-

19c19c39c-35c

7490—65c 74153—75c74LS90—95c 74154-1.00

74LS74-59C7475—69c7476—35c7480—49c7483—95c7485—95c7486—45c

7492-7493-7495-7496-

■75c-69c-75c-89c

74121-38C74123-65C74132-1.70

74157—75c74161—95c74164-1.1074165-1.1074174—95c74181-2.5074191-1.25

TTL INTEGRATED CIRCUITS

74S138-1.95 74192-1.25

74141-75C 74193-1.00

74195—69c

P.C. LEADDIODES

1N4148/1N914100/$2.001N4002-1A.100 PIV 40/$l.

HEAVY DUTY

Full Wave Bridge

25 AMP 50 PIV

$1.25

Disc CapAssortment

PC leads. Atleast 10 differentvalues. Includes.001, .01, .05,plus other stan-dard values. „

60/$1.00 "23D

$9.95

KIT

P.C. Board - 3.00

AC XFMR - 1.50

Do not confuse with Non-Alarm

kits sold by our competition!

Eliminate the hassle —

avoid the 5314!

SIX DIGIT ALARM CLOCK KIT

We made a fantastic kit even better. Redesigned to take advantage of thelatest advances in I.C. clock technology. Features: Litronix Dual %"displays, Mostek 50250 super clock chip, single I.C. segment driver, SCRdigit drivers. Greatly simplified construction. More reliable and easier tobuild. Kit includes all necessary parts (except case). P.C.B. or XFMRoptional. NEW! WITH JUMBO LED READOUTS!

Motorola SCR

2N4443. 8 AMP 400 PIV.P.C. Leads 3/$-|_

FAIRCHILD-TBA641

4W. Audio power Amp. Just

out! In special heat sink

DIP. One super audio IC.

$1.50 with data

FND-359 -Led Readout

.4 IN. Common Cathode.High effeciency. Has FND-70 PIN OUT. 5gc

OUR CATALOG

is chocked full of rare parts

bargains, deals, RAM or CPU

kits, plus much more. Yours

FREE!

PRICES SHOWN SUBJECT

TO CHANGE WITHOUT

NOTICE.

$15.95

COMPUTER POWER SUPPLY

A very fortunate purchase. One of the best industrial quality REG-ULATED supplies we have seen. High performance, small size.Input is 120 VAC 60 HZ. Has the following regulated outputs:-5VDC@800MA; -15VDC @ 1.25 AMP; -25VDC <a> 180 MA.Sold at a fraction of original cost. Do yourself a favor and orderNOW. We expect a quick sellout.

NEXT MONTH:S.D. will have music for your ears. Watch our ads.

For your Imsai or Altair 8080 Computer:Z-80 CPU Kit - $149. 4K Low Power Ram Kit

$89.95

Terms: Money back guarantee.No COD. Texas residents add5% sales tax. Add 5% of orderfor postage & handling. Or-ders under $10. add 75c.Foreign orders: US fundsonly!

Call your Bankamericard orMaster Charge order in on ourcontinental United Statestoll free Watts:

1-800-527-3460

Texas Residents Call Collect:

214/271-0022

Special Thanks to:

Dennis, Fred, Abe, Bill, Sam,

Hal, Tom, Alex, John, Ely,

and Larry

S.D. SALES CO. ^P. O. BOX 28810 UlDallas, Texas 75228

ORDERS OVER $15.00 - CHOOSE $1.00 FREE MERCHANDISE

F8 EVALUATION BOARD KIT WITH EXPANSION CAPABILITIES

A fantastic bargain for only

20 ma of RS 232 interface64K addressing rangeProgram control timers1K off on board static memory

$99

with the following features:

00 • Built in clock generator

• 64 Byte register

• Built-in priority interrupts

• Documentation

GENERAL PURPOSE COMPUTER POWER SUPPLY KIT

This power supply kit features a high frequency torroid transformer

with switching transistors in order to save space and weight.

115V 60 cycle primary. The outputs with local regulators are + 5V S7Q^^

to 10A, in one amp increments,—5V at 1 A, ± 12V at 1A regulators supplied * **

6 340T-5 supplied.

UNIVERSAL 4K MEMORY BOARD KIT

$74

50

This memoryboard kit can be used with most microcomputers.Some of the outstanding features are:

32-2102-1 static RAM's, 16 address lines, 8 data lines in, 8 datalines out, all buffered. On board decoding for any 4 of 64 pages,standard 44 pin, .156" buss.

4K F8 Basic $25.00

2522STATICSHIFTRE6 S 1.95

2513CHARACTER GEN S 9.95

2518-HEX 32 BITSR $ 3.50

2102-1 1024 BTRAM $ 1 49

5280-4K DYNAMIC RAM $ 6.95

5202A UV PROM S 6.95

MM5203 UV PROM $ 6.95

1 702A UV PROM $ 6.95

5204-4K PROM .' $10.95

MINIATURE MULTI-TURN TRIM POTS100,500. IK. 2K.5K,10K,100K,200K. 1 Meg.

S 75 each 3/S2.00

MULTI-TURN TRIM POTS Similar to Bourns3010 style 3/l6"x5/8,'x1 -1 /4": 50. 100,IK, 10K, 50Kohms

$1.50ea 3/S4.00

LIGHT ACTIVATED SCRs

TO-18, 200V 1A $1.75

TRANSISTOR SPECIALS

2N3585 NPN Si TO-66 S .95

2N3772 NPN Si TO-3 S 1.60

2N456A PNP GE , S .75

2N4908 PNP Si TO-3 S 1.00

2N6056 NPN Si TO-3 Darlirkjion . S 1.70

2N5086 PNP Si TO-92 4/S 1.00

2N4898 PNP TO-66 S .60

2N404 PNP GE TO-5 5/S 1.00

2N3919 NPN S. TO-3 RF S 1.50

MPSA 13 NPN Si TO-92 3/S 1.00

2N3767 NPN Si TO-66 $ .70

2N2222 NPN Si TO-18 5/S 1.00

2N3055 NPN Si TO-3 S .80

2N3904 NPN Si TO-92 5/S 1.00

2N3906 PNP Si TO-92 5/$ 1.00

2N5296 NPN Si TO-220 S .50

2N6109 PNP Si TO-220 $ .55

2N3638 PNP Si TO-5 5/S 1.00

2N65I 7 NPN TO-92 Si 3/$ 1.00

C/MOS (DIODE CLAMPED)

74C02- .22 4015- .95 4029-1.10

74C10- .22 4016- .40 4030- .22

74C193-1.50 4017-1.05 4033-1.50

4001- .22 4018-1.00 4035-1.10

4002- .22 4019- 25 4042- .784006-1.20 4020-1.05 4047-2.004007- .22 4022- .95 4049- .40

4009- .42 4023- .22 4050- .40

4010- .42 4024- .75 4055-1.50

4011- .22 4025- .22 4066- .80

4012- .22 4026-1.25 4071- .22

4013- .40 4027- .40 4076 1.05

4028- .88

MCA-81 OPTICAL LIMIT SWITCH. Si .50

LED READOUTS

FND 500-.5" C.C SI 25

HP 7740.3" C.C S 95

MAN-7-.3" C.A S 95

NS 33-3 din. array $ ;75

DL 747 SI 60

Terms: FOB Cambridge, Mass.Send Check or Money Order.Include PostaOrder $5.00, C._

PRINTED CIRCUIT BOARD

TANTULUM CAPACITORS

4-1/2 x6-1/2" S'NGLBOARD 1/16" thick, iS.50 ea

SIDED EPOXYTetched 5/S2.20

7WATTLD-65.LASERDIODEIR $a95

2N3820PFET $ 45

2N 5457 N FET $ 45

TIS43 UJT $ 35

ER 900TRIGGER DIODES .. 4/?1 002N 6028 PROG. UJT . . . S 65

8 PIN DIP SOCKETS .... S 24

14 PIN DIP SOCKETS $ 25

1G PIN DIP SOCKETS $ 28

18 PIN DIPSOCKETS $ 30

24 O'N DIP SOCKETS $ 40

40 PIN DIPSOCKETS $ GO

VERIPAX PC BOARDriiis hoard is u 1/16" single sided paper epoxyboard, 4Wx6W DRILLED and ETCHEDwhich will hold up to 21 single 14 pin IC'sor 8, 16, or LSI DIP IC's with busses (orr supply connector $4.DO

MV5691 YELLOW-GREEN

BIPOLAR LED S1

FP 100 PHOTO TRANS ... $

RED, YELLOW, GREEN OR

AMBER LARGE LED's . , ea S

MOLEX PINS 100/S1

1000/S710 WATT ZENERS 3.9, 4.7, 5.6, 8.2, 10,12. 15,18. 22, 100. 150 or 200V ea. $.1 WATTZENERS 4.7, 5.6.

18 OR 22V ea. $

MC6860 MODEM CHIP. ... £q

Silicon Power Rectifiers

25

100

.06

.14

200

400'

.0/

.00

.20.25

600

11

.30

R00

1R

.35

.50 1.40

6.50

.70 I ,B0

8.50

.90 2.30

10.50

45 1.10 2.75 12.50

SILICON SOLAR CELLS

2%" diameter.4V at 500 ma. $4.00 / .2V at 200 mils $1

REGULATED MODULARPOWER SUPPLIES

• - 15 VDC AT lOOma

115VAC INPUT S27.95

5VDC AT 1 A. 115VAC INPUT . . . S24.95

12 VDC AT .5 AMP $24 95

_INJJ48_I INjjj 4) . 1575T0D~

Send 25(5 for our catalog featuringTransistors and Rectifiers

jre St.,_ Cambridge, Mass.

22UF 35V 5/S 1.00.47UF 35V 5/S1.00.68UF 35V 5/S1.001UF 35V 5/S 1.002.20UF 20V5/S1.003.3UF 35V 4/S 1.004.7UF 35V 4/S1.00

b.BUF 35V 3/S1.00

22UF 35V S .40

30UF 6V S .40

33UF 35V S .40

47UF 20V 5/S1.00

100UF 35V S 35

150UF 15V S .50

M/001 ALARM CLOCK CHIP. . .

NATIONAL MOS DEVICES

MM1402- 1.75MM1403- 1.75MM1404- 1.75MM5013- 2.50MM5016-2.5OMM5017-2.70MM5055- 2.25MM505G- 2.25

MM5057- 2.25MM5058- 2.75MM5060- 2.75MM50G1- 2.50MM5555- 4.75MM5556- 4.75MM5210- 1-95MM5260- 1.75

7400-7401-7402-7403-7404-7405-7406-7407-7408-7409-7410-7411-7412-7413-7414-7416-7417-7420-7425-7426-7427-7430-7432-7437-7438-7440-7441-7442-

TTL IC SERIES

7445- .70

. S5.75

74151-

7446-7447-7448-7450-7472-7473-7474-7475-7476-7480-7483-7485-7486-7489-1.85

7490- .45

7491- .70

7492- .50

7493- .45

7494- .70

7495- .70

7496- .7074107- .3274121-74123-74125-74126-74132-

.70

.30

.38

.79

74153-

74154- 1,10

74155- .7074157- .7074161- .85

74163- .80

74164- .9574165-1.0574173-1.40

74174- .95

74175- .92

74176- .7574177-7418074181-2.1074190-1.20

74191- 1.20

74192- ,85

74193- .85

74194- .85

74195- .75

74196- .8874257- 1.2574279- .9075324- 1.75

75491- .65

75492- .65

MINIATURE DIPCTS-206-4 Four SPST

SWITCHESswitches

in one

mm id

p package.

SI

.75

CTS 206-8

Eight

SPST

switches

n a

16

pin DIP

pack

age. .

$1

.95

5-8VSPST Miropen, 330 Ohn

ftLCU MINIATURE TOGGLE SWITCHES

MTA 106 SPDT SI .20

MTA 206 DPDT $1.70

SOLID STATE SALES

P.O. BOX 74B

SOMERVILLE, MASS. 02143 TEL. (617) 547-4005

Full Wave Bridges

^RV 2A 6A 25A

200 .7$ fSj 2.QO

400 .05 1Jjp_ 3.00

600 K20 T75; 4.0Q

SANKEN AUDIO POWER AMPS

Si 1010 G 10 WATTS S 7.95

Si 1020 G 20 WATTS $ 15.95

Si 1050 G 50 WATTS $27.95

CCD 110 LINEAR 256 XI BITSELFSCANNING CHARGED COUPLED

DEVICE S65.0Q

CCD 201 - 100 x 100 CHARGECOUPLED DEVICE S99.00

LINEAR CIRCUITS .

LM307-Op. Amp S .30

LM309K 5V 1A REGULATOR .. S .95

723-40+ 40VV REGULATOR . . S .50

301/748-Hi Per. Op. Amp S .31

320T 5.1 2,15, or 24V NEGREG . . $1.25

709C Op. Amp 3 31

78MGS-Pos 5 to 30V. 500 ma reg. SI 35

79MGS-N.;g 5 to 30V, 500 ma reg. SI 35

CA 3047 Hi Pel. Op. Amp $ 95

340T 5. 6. 8, 12, 15, 18, 24V POS

REG. TO-220 si 10

741A or 741C OP AMP $ .31

LM 308 Oper. Amp., Low Power . . S .95

747 - DUAL 741 S .65

556 - DUAL TIMER S1.00

1456 - Oper. Amp S .95

LM 3900-QUAD OP. AMP .... S 49

LM 324 - OUAD 741 SI 50

560 - PHASE LOCK LOOP .... S2 00

561 -PHASE LOCK LOOP .... S2 00

565 - PHASE LOCK LOOP .... * S1 25

566 FUNCTION GEN SI 65

567 - TONE DECODER Si 50

LM 1310N FM STEREO DEMOD. . S2 75

8038 IC VOLTAGE CONT. OSC. . S3 90

LM 370 - AGC SQUELCH AMP. . Si 15

555 - 2ps - 2 HR. TIMER S .45

553 OUAD TIMER $ .45

IL5 (MCT-2) OPTOISOLATOR .. $ .80

1458 DUAL OP AMP S 60

LM 380 - 2W AUDIO AMP $ .95

LM 377 - 2W Sieioo Audio Amp. . S2.50

LM381 - STEREO PREAMP. . . . SI.50

LM 382 - DUAL AUDIO PREAMP SI.50

LM311 - HI PER. COMPARATOR S .90

LM 319 - Dual Hi Speed Comp. . . S1.25

LM 339 - QUAD COMPARATOR S1.50

.70 1.10 1.75

1.10 1.60 2.60

1.70 2.30 3.60

\X>0 V20 2.20

1.50 3.00

WE SHIP OVER 95%

OF OUR ORDERS THE

DAY WE RECEIVE THEM

DIP PLUGS AND COVERS

Use for

mounting diodes, res

store.

jumpers,

etc.

Gold pi

□ ted ports for long weor.

PLUGS

COVER!

1-24 25-49

a

-99

1-24

25-99

Bpin

.46 .39

.32

.10

.09

14 pin

.48 .40

.34

.10

.09

16 pin

.56 .47

.38

.10

.09

24 pin

.79 .72

.65

.15

.13

40 pin

SI.23 SI.08

.93

.25

.22

DIP PLUG INTERCONNECTS

Ideal for use from board to board, remote switches, in test

equipment, lamp panels, etc. Made from gold plated

connectors, color coded ribbon cable, molded plugs.

Very flexible and durable.

To order, make up part number from characteristic and find

price in chart. For instance; S-14P-18 is single ended 14 pin

nterconnect 18 inches in length. Price is SI .72. D-24P-06

s double ended 24 pin, 6 inches in length. Price is $4.55.Quantity pricing is available.

PRICE CHARTSNo Of Pins

SINGLE END

PRESTR1PPED WIRE WRAP WIRE

Highest quality 30 go, Kynar insulated silver plated wire forwrapping. Stripped 1" an both ends. Indicated lengths arelengths of insulated portion. Packed 100 per sturdy plasticvial or 1000 per poly bog. Compare our prices 'M. Availablein Black, Red, Yellow and Green. $tate color desired.

Price per bag of 1000SI 1.84 (*WW30BK-1)$12.80 (*WW30BK-2)S14.80 (#WW30BK-4>S17.60 (rfWW30BK-6)

Length Price per tube of 1001" SI.48 [WW30VC-112" SI.60 (WW30VC-2)4" $1.85(WW30VC-4)6" $2.20 (WW30VC-6)Dealer Inquiry InvitedROLLS OF WIRE SAME AS ABOVE (30 go. KYNAR)100ft Roll in poly bag...$3.45 10 Rolls, mixed $24.00

WIREWRAP I.C. SOCKETS, 3 LEVEL GOLD

14 pin 38? ea, 10 for $3.60 16 pin 42c eo, 10 for S3.90

^

HIGH CURRENT STUD DIODES v

D2131 200V, 25A S .85

D2I35 400V, 25A SI .00

D2138 600V, 25A SI.55

3289 200V, I00A S5.85

Contract Cancellation Specials All Full Spec, NEW!!

SN7490 39c 2N3734 38c 2N3773 SI .75

2N5861 75c 2N4401..5/S1

IN3572 90c 2N4403..5/S!

G.E.D45C5 44$ 2N1557..S1.3950V, 3Amp Epoxy Bridge 79c;

LM320H-I2...S1.29

IN5231A 25c

1N52263 35c

741(mini-dip..3/SI

YOU CAN STORE A WORLD OFDATA ON THE KEY TO TAPERECORDERS FROMTRI-TEK.SHARE A BYTE WITH A FRIEND.

KEY TO MAGNETIC TAPE DATA RECORDERS

Anny is shown operating one of these versatile units which consists of a 1/2" magnetic tape recorder sitting on top ofkeyboard/controller/display module. These units were made by PERTEC, one of the most respected names in data re-cording ond were used to replace punched cord input. They are of late design and recent manufacture. From the op-erators chair, it is just like a key-punch. Instead of data going into cards in Hollerith, it goes onto Mag tope inEBCDIC. They may be used for that purpose or the tape drive can be separated, control and data lines brought outfor use directly on your system. Has internal memory/buffer for 80 or 200 character storage. Display panel indicatescharacter, character number, record number. Read back circuits allows search on record key, editing, duplicating...!These are not obsolete!!! A giant factory closing brings you these at about 5c on the dollar. All units are completeond in good condition. They hove not been functionally tested but have been inspected for damage. All are sold onas is basis. There are national service shops for these units and parts ore available. Hundreds of these units arebeing used right now in business and industry.

Prices are as is (complete and inspected), F.O.B. our warehouse in Rochester, N.Y. and shipped by truck, freightcollect only. Unit weight is approximately 70 lbs. Comes in 7 or 9 track versions. 'Model 4311 has remote datacommunication channel. All units, less tape.

KT-4301-7 7 track data recorder S249.00

KT-4311-7 7 track with remote 5299.00

KT-4301-9 9 track data recorder S329.O0

Operators and maintenance manualsfsold separately only)S20

!•;►

PROFFESSIONAL LOGIC SYMBOL TEMPLATEMIL-STD 806-B (Half Size) $3.25

Fast Signal Diode

115V VR 100mA If. Reverse recovery time Is less than20 nS at 100mA forward! 6 pf cap. Same size as1N914, 1N4148. D600 20/$l

TO-5 Heat Sink. THERMALLOY 2211 B 2-piece black

anodized for maximum heat dissipation. HS221IB* 5/S1SEMlECH S1-2 200V, 1.5A diode. Gold leads.. .12/$].6.8V, 50Watt Zener. Made by Motorola in TO-3cose. Gold plated SI .00

NEW BOOK FROM NATIONAL

MOS LSI. Giant dato book filled with spec and appson large scale MOS circuits from National SemiconductorCorporation Price includes shipping in U.S. only...$4.25Outside U.S., odd postage for 2 lbs.

MCM6571 Full ASCII Character Generator $9.95

DATA BOOKS BY NATIONAL SEMICONDUCTOR

DIGITAL. Covers TTL, DTL, Tri-State, etc S3.95

LINEAR. Covers amplifiers, pre-amps, op-amps... $4.25LINEAR APPLICATIONS VOLUME I. Dozens ofapplication notes and technical briefs covering theuse of op-amps, regulators, phase locked loops and

audio amps , $3.25

LINEAR APPLICATIONS VOLUME II. Takes up whereVolume I left you—All the latest linear devices.Along with Vol I you hove a great source of app-lication data on the most widely used devices as well

as new types just appearing $3.25

CMOS Gates, Flip Flaps, registers, etc $3.00

VOLTAGE REGULATORS. A must for anyone makinga power supply. Complete theory including transform-ers, filters, heat sinks, regulators etc S3.00

MEMORY. Info on MOS and Bipolar memories, RAMS

ROMS. PROMS and decoder/encoders S3.95

INTERFACE. Covers peripheral drivers, level trans-lators, line driver/receivers, memory and clock drivers,

sense amps, display driver and opto-couplers $3.95

SPECIAL FUNCTIONS DATA BOOK. Contains de-toiled information for specifying and applying specialamplifiers, buffers, clock drivers, analog switches and

D/A-A/D converter products..... $3.25

AUDIO HANDBOOK Contains detailed discussions,including complete design particulars, covering manyareas of audio with real world design examples... $3.25

tRi tek, inc.

6522 noRth 43R6 Avenue,

QlenOale. arizoita 85301

phone 602 - 931-6949

We pay surface shipping on all orders over S10 US, $15 foreign in US funds.Please add extra for first class or air mail. Excess will be refunded. Ordersunder SI 0, add $1 handling. Please add 50c insurance. Master charge andBank America cards welcome, (S20 minimum). Telephone orders may be placed10AM to 5:30PM daily, Mon thru Fri. Call 602-931-4528. Check readerservice card or send stamp for our latest flyers packed with new and surpluselectronic components.

Reader Service

To get further information on the products advertised in BYTE, fill out the readerservice card with your name and address. Then circle the appropriate numbers for theadvertisers you select from this list. Add a 9 cent stamp to the card, then drop it in themail. Not only do you gain information, but our advertisers are encouraged to use themarketplace provided by BYTE. This helps us bring you a bigger BYTE.

Reader

Service

Number

PageNumber

232 Abbott Computer Co 147

75 Advanced Microcomputer Products 165

168 Aldelco161

255 Alpha Digital Systems 147

1 73 Anderson Jacobson 48

225 Bay Area Time Share 147

4 BITS Inc 129, 130, 131, 147, 148, 155

149 Bits and Bytes 151

217 BPI 67

227 Byte Shop East Inc 151

126 Cheap Inc 151

127 Comptek 160

38 Compucolor 14, 15

140 Computalker 151161 Computer Corner 151253 Computer Electronics 159143 Computer Enterprises 160244 Computer Kits 104

176 Computer Mart of NH 157

83 Computer Mart of NY, LI 152

156 Computer Place 157

141 Computer Room 114208 Computer Shack 97

246 Computer Shoppe (NY) 157

203 Computer Systems 157

138 Computer Warehouse 166

6 Continental Specialties 73

202 CRC Engineering 117

87 Creative Computing 139

41 Cromemco 1, 2

178 Cybercom 7

185 DAJEN Electronics 157

223 Datasearch 150

Reader

Service Page

Number Number

78 Digital Group 19

210 M W Dunton 157170 ECDCIII

79 Economy Co 45

211 Economy Terminals 159

247 Electravalue 159

47 Electronic Control Technology 159

254 Electronic Discount Sales 159

241 Expandor151

248 Franklin Electronics 459 Godbout 167, 168

* HAL Communications 12567 IEEE 115

12 IMSAI 13, 49

60 Interface Age 106

204 International Data Systems 128

15 James 169, 170

158 Lillipute 159

209 Logic Design Inc 161

* London Conference 142

* MACC 149124 McGraw-Hill 25

18 Meshna171

242 Micromation 110196 Micronics 161

77 Micro-Term 69

188 Microware 154

174 Microtex 161

249 Microtronics 161

119 Midwestern Scientific Inst 83

Reader

Service Page

Number Number

57 Mikos172

112 Miniterm 105, 107, 109, 111

21 MITS CIV

62 Morrow 164

250 Mountain Hardware 16171 mpi 158

171 Mullen 158

* NCC 134, 135

155 North Star Computers 116

40 Ohio Scientific Inst 47

147 OK Tool 9, 121

64 Oliver Audio Eng 163

198 Omni 156

63 Parasitic Eng 127, 156

* PCC77 140

* PerCom Data 12, 143194 Peripheral Vision 61

* Personal Computing Expo 141

* Polymorphic Systems 11213 Prime Radix 31

24 Processor Technology 5, 16, 21, 27

167 Quay112, 113

251 Qubed3 163177 Resco150

219 RHS Marketing 118, 119201 Riverside Electronic 153234 Rotundra Cybernetics 163226 Scelbi 23

* Scientific Research 36, 3727 SD Sales 173

236 Seals 29

169 Smoke Signal Broadcasting 108

59 Solid State Sales 174

29 Southwest Tech CM

164 Sunny Computer Stores 163

96 Synchro-Sound Enterprises 74, 75

205 Szerlip 163

121 Tarbell Electronics 154

82 Technical Design Labs 33

136 Technical Systems Consul 133186 Technico 55

32 Tri-Tek 175

228 VAMP Inc 163

137 Vector Graphic 8, 122, 123154 Worldwide Electronics 145222 Xybek152

220 Ximedia71

ecMe-

EYTE's Ongoing Monitor Box

On BOMB Card,Article No.

ARTICLE

1 Lau: A Catalog of Liberating Home Computer Concepts

2 Wimble: Artificial Intelligence, An Evolutionary Idea: Part 1

3 Wozniak: The Apple-ll

4 Ciarcia: Come Upstairs and Be Respectable

5 Carr: Interfacing with an Analog World—Part 1

6 Linker: What's in a Floating Point Package?

7 Brehm: Using a Keyboard ROM

8 Emmerichs: Implementing the Tiny Assembler

9 McNatt: A Guide to Baudot Machines: Part 2

10 Chapman: All This Just to Print a Quotation Mark?

11 Krystosek-McCarty: 8080 Programming Notes

PAGE

172634505662768498132136

"Reader service inquiries not solicited.Correspond directly with company.

Bombed . . .

The results of the BOMB tabulation forthe month of January have now beenprepared by Greg Spitzfaden. First prizewinner in the contest was Dr Kenneth BWelles, for his article "Build This EconomyFloppy Disk Interface." Second placewinner was "The Digital Cassette Subsystem,Part 1" by Ira Rampil and Jack Breimier.First place winner Welles receives a $100bonus check, and second place winnersRampil and Breimier receive a bonus of$50."

176

Tr>« © )>n-i% n.ertt.A* Jitaltv tmtll

CM net if fi'i|t — |]| t.fftMftt I i 12, ••ftvara-dtf IMH «•* Mtria cfttrKttPi, l f*»m ai 21 •' *lIimi of 19 t* 121 characttri »*r mm, ill ch*a|t»aii

■ o | c I \ o J l, l \

OJLfi. LftLUl **' * k't MttfFfi Vith a 121 > 1*1 t*v*rt

d.ipiav, tacK iflwt'i iMivitaallv itttMlt.

For rtioivT.cn, aaaunt e' tait. »»i «grapnel. Mothmf ea« taveti it.

KeyInto

Maxi-Power <g> Micro-Price

Micromind is an incredibly flexible,complete and expandable, hardware/software, general purpose computersystem. You won't outgrow it.

Hardware includes an 80 key, software-definable keyboard, I/O interface board,6500A-series microprocessor (powerfulenough for advanced computing), a high-detail graphics and character displayprocessor, power supply, rf modulator,and connections for up to 4 tape recordersplus TV or monitor. An interconnect bus

powerful assembler, a debugger, a filesystem, graphic routines, and peripheralhandlers. We also include dynamic graphicgames: Animated Spacewar and Life.ECD's standard Micromind /xM-65supplies 8K bytes of memory. Additional

32K byte expansion boards and a mappingoption give Micromind expandable accessto 64 Megabytes. Utilizing software-controlled I/O channels, Micromind'sadvanced encoding techniques load datafrom ordinary tape recorders at 3200bits per second.

Micromind comes to you ready-to-use,factory assembled and fully tested. Amongmicrocomputers, it has the largest memorycapacity and the fastest storage. You'relooking at the work of the finest displayprocessor on the market. You won't find amicrocomputer with a more powerful CPU.You won't find a computer with amore flexible keyboard. You won't .find anything to

touch it at_*^ $987.54.

permits 15 additional microprocessors,parallel processing and vastly increasedcomputing power.

System software—including ECD's ownnotsoBASIC high level language, onadvanced error-correcting tape cassettes—provides a word processing editor, a

So, quit the kluge scene and key intoMicromind. You'll be a main frame per-former, with all the comforts of home.We're not fooling...this js the cat's fx\

ECD CORP.196 Broadway, Cambridge, Mass. 02139(617)661-4400

€CJ>

Name.

Address.

City/State.

Zip.

□ Fantastic! Check enclosed: $987.54. shipping paid by ecd

□ BankAmericard D Master Charge Mass. Resident add 5% Sales Tax

# Expiration Date

Signature

D Send me your brochure.

Actual unretouched photographs.

*

•

It Comes Naturally WithThe Altair™ 8800b

The Altair 8800b from MITS: the second gen-eration design of the microcomputer thatstarted it all. The mainframe that has the abil-ities everyone is demanding from microcom-puters today:

Expand-ability:

The Altair 8800b power supply and one-piece, 18-slot motherboard allow efficientand easy expandability for memory and I/Ooptions. All Altair PC boards are designed togive you maximum capability/lowest powerusage possible per board. This means thatfor each slot used you get more features andrequire less power, than with any of the "off-brand" Altair-bus-compatible boards.

Whether you buy an entire system up front orchoose to expand gradually, it's easy to getthe configuration you need-with the com-plete family of Altair peripheral equipment,including _

floppy disk, lineprinter, audiocassette recordinterface, A/Dconverter, •

PROM program-mer, serial andpara""'

choice of four different memory boards andmany others.

Reli-ability:

The unique design features of the Altair8800b, which have set the standard for themicrocomputer industry, make it the mostreliable unit of its kind. The Altair 100-pin bus,the now-standard design used by many imi-tators, has been "standard" all along at MITS.The unique Front Panel Interface Board onthe Altair 8800b isolates and filters front panelnoise before it can be transmitted to the bus.The all-new CPU board utilizes the 8080Amicroprocessor, Intel 8224 clock generatorand 8216 bus drivers.

Flex-ability:

Meeting the diversified demands of an ever-fneiteaSirtg" rY\icfbprb6es8oT market requiresflexibility: not just hardware flexibility but

software flexibility as well. MITS software,including the innovative Altair BASIC lan-guage, allows the full potential of the Altair8800b computer to be realized.8K AtlAIR BASIC has facilities for variablelength strings with LEFTS, RIGHTS, and MID$functions, a concatenation operator, andVAL AND STR$ functions to convert betweenstrings, and numbers.

Extended ALTAIR BASIC allows integer, singleand double precision variables, automaticJine numbering and renumbering, user-defined string functions, PRINT USING for for-matted output and a powerful EDIT com-mand for editing program files during or afterentry. Extended statements and commandsinclude IF. . . THEN . . , ELSE, LIST and DELETEprogram lines, SWAP variables and Trace Onand Off for debugging.

Disk ALTAIR BASIC has all the features ofExtended BASIC with the additional capa-bility to maintain sequential- and randomj access disk files. Utilities Ore provided forformatting disks and printing directories.

In all versions of ALTAIR BASIC you get the

ease dnd efficiency of BASIC for the solution

of real world problems.^Package^ |l, an gssembly language develop.-*ment system for the Altair 8800b, includes

system; monitor, text editor, assembler and

debugi j

Afford-ability:

I Prices for the Altair 8800b start atI $840.00 for a kit and $1100.00 for anassembled unit (all documentationincluded).

For a complete listing of prices onall Altair products and a free bro-chure, contact:

MITS, Inc.2450 Alamo S.E.Albuquerque, N.M. 87106

NOTE: Altair is a trademark ol MITS, Inc