Byte Magazine Volume 06 Number 03 - Programming Methods

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50 to 38,400 baud operation — programmable

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8212 — twelve-inch diagnonal screen or 8209 — nine-inch diagnonal screen

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And our micros have some disk drives AS WELL AS (c) 8-inch outstanding advantages.

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UNEQUALLED SOFTWARE SUPPORT

OK. That was one point.

Here's another: our stunning selection of software support. Cromemeo is the only micro manufacturer to produce both single-user and multi-user multitasking computers with software like this:

The competition will always sing the praises of their little single board computers. But from how on they'll be doing it falsetto.

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CDOS (a CP/M®* -like operating

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RPG-II (IBM-compatible)

COBOL

BASIC

FORTRAN IV

RATFOR

LISP

C

Macro Assembler

APPLICATION SOFTWARE

Word Processing System Data-Base Management General Ledger Accounts Receivable Accounts Payable Inventory

All of this is available now with more coming all the time.

So there you are, D.G.

You can see why we know our microcomputers will stand the test.

Cromemeo eagerly accepts the challenge.

* CP/M is a registered trademark of Digital Research.

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Tomorrow's Computers Today

280 BERNARDO AVE. MOUNTAIN VIEW, CA 94043 (415) 964-7400 • TWX 910-379-6988

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BYTE March 1981

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Get the professional color

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Here's a color display that has everything: professional-level resolution, enormous color range, easy software, NTSC conformance, and low price.

Basically, this new Cromemco Model SOI* is a two-board interface that plugs into any Cromemco computer.

The SDI then maps computer display memory content onto a convenient color monitor to give high-quality, highresolution displays (756 H x 482 V pixels).

When we say the SDI results in a highquality professional display, we mean you can't get higher resolution than this system offers in an NTSC-conforming display.

The resolution surpasses that of a color TV picture.

BASIC/FORTRAN programming

Besides its high resolution and low price, the new SDI lets you control with optional Cromemco software packages that use simple BASIC- and FORTRANlike commands.

Pick any of 16 colors (from a 4096-color palette) with instructions like DEFCLR (c, R, G, B). Or obtain a circle of specified size, location, and color with XCIRC (x, y, r, c).

•U.S. Pat. No. 4121283

Model 5DI High-Resolution Color Graphics Interface

HIGH RESOLUTION

The SDI's high resolution gives a professional-quality display that strictly meets NTSC requirements. You get 756 pixels on every visible line of the NTSC standard display of 482 image lines. Vertical line spacing is 1 pixel.

To achieve the high-quality display, a separate output signal is produced for each of the three component colors (red, green, blue). This yields a sharper image than is possible using an NTSC-composite video signal and color TV set. Full image quality is readily realized with our highquality RGB Monitor or any conventional red/green/blue monitor common in TV work.

Model SDI plugs into Z-2M 11-mcgabyte

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DISPLAY MEMORY

Along with the SDI we also offer an optional fast and novel two-port memory that gives independent high-speed access to the computer memory. The two-port memory stores one full display, permitting fast computer operation even during display.

CONTACT YOUR REP NOW

The Model SDI has been used in scientific work, engineering, business, TV, color graphics, and other areas. It's a good example of how Cromemco keeps computers in the field up to date, since it turns any Cromemco computer into an up-to-date color display computer.

The SDI has still more features that you should be informed about. So contact your Cromemco representative now and see all that the SDI will do for you.

ra

Cromemco

^^^^M 280 BERNARDO AVE., MOUNTAIN VIEW, CA 94043 • (415)964-7400

^^^ Tomorrow's computers today

Circle 1 on inquiry card.

In The Queue

Volume 6, Number 3

March 1981

Features

20 Structured Programming and

Structured Flowcharts by Gregg Williams

A technique that makes programs easier to write, understand, fix, and change.

36 Build the Disk-80: Memory Expansion and Floppy-Disk Control by

Steve Garcia / Steve discusses how to use dynamic memory and floppy-disk-controller integrated circuits and presents a design that incorporates them.

54 Three-Dimensional Computer

Graphics, Part 1 by Franklin C Crow / Ways to display solid objects with the removal of hidden lines and surfaces.

132 What Is Good Documentation?

by Jim Howard / How to write clear and effective documentation.

166 A Beginner's Guide to Spectral

Analysis, Part 2 by Mark Zimmermann

Images can be transformed into holograms via Fourier transforms.

262 A Simple Approach to Data

Smoothing by Fred Ruckdeschel and Janice A Krinsky / The techniques described here can aid in the interpretation of data taken from realworld situations.

300 The New Literacy: Programming

Languages as Languages by Jon Handel

BASIC, ALGOL, and APL are compared to the English language.

317 Computer Music: A Design

Tutorial by Thomas P Orlofsky / A modest amount of theory provides the background for building a simple program-controlled digital tone generator.

Reviews

84 The Micro Matrix Photopoint Light

Pen by Stephen B Gray

90 What's Inside Radio Shack's Color Computer? by Tim Ahrens, Jack Browne, and Hunter Scales

Nucleus

6 Editorial: Is This Really Necessary? 12 Letters 152, 333 Programming Quickies: Computing the

Determinant of a Matrix: Constellation I: An

Astronomy Program 155 Languages Forum: A Coding Sheet for FORTH 164, 314, 316 BYTE's Bits 216, 224, 234 Technical Forum: DATALINE; Addition

and Subtraction: The 1802 Versus the Z80; Build

a Simple Video Switch 230 Desk-Top Wonders: Hunt the Wumpus with

YourHP-41C 236 System Notes: Software Addressing Modes for

the 8080 242 BYTELINES 248 Software Received 252 Books Received 254 Ask BYTE 308 Event Queue 315 Clubs and Newsletters 337 What's New?

382 Unclassified Ads

383 BOMB, BOMB Results

384 Reader Service

SITE

Page 34

Page 54

Page 132

Page 317

March 1981 © BYTE Publications Inc 3

m

Editor in Chief Christopher Morgan

Technical Editors

Richard S Shuford, Gregg Williams;

Curtis P Feigel; Harold Nelson;

Stan Miastkowski; Kevin Cohan; Bruce Roberts.

Charles Freiberg. New Products Editor;

Steve Ciarcia. Mark Dahmke.

Consulting Editors;

Jon Swanson. Draftsman

Copy Editors

Richard Friedman, Chief; Faith Hanson; Warren Williamson; Robin M Moss; Anthony J Lockwood; Ann Graves

Assistants

Faith Ferry; Debe Wheeler; Karen A Cilley;

Production

Nancy Estle. Director. Christine Dixon. Asst Director; Wai Chiu Li; Holly Carmen LaBossiere; Deborah Porter. Sherry McCarthy. Chief Typographer. Debi Fredericks; Donna Sweeney. Valerie Horn

Advertising

Thomas Harvey. Director; Ruth M Walsh; Marion Gagnon; Barbara J Greene; Rob Hannings

Circulation

Gregory Spitzfaden. Manager; Andrew Jackson, Asst Manager; Agnes E Perry; Barbara Vamum; Louise Menegus; Bill Watson; Dealer Sales: Melanie Bertoni

Marketing

Jill E Callihan. Special Projects; Laura Hanson

Controller's Office

Daniel Rodngues. Controller; Mary E Fluhr. Asst Controller; Karen Burgess; Jeanne Cilley

Traffic

Mark Sandagata; N Scott Gagnon

Receptionist

Jacgueline Earnshaw

Publishers

Virginia Londoner; Gordon R Williamson; John E Hayes. Associate Publisher. Cheryl A Hurd. Publisher's Assistant

Officers of McGraw-Hill Publications Company: Paul F McPherson. President; Executive Vice Presidents: James E Boddorf, Gene W Simpson. Group Vice President: Daniel A McMillan; Senior Vice President-Editorial: Ralph R Schulz; Vice Presidents; Kemp Anderson, Business Systems Development; Stephen C Croft. Manufacturing; Robert B Doll. Circulation; James E Hackett. Controller; William H Hammond. Communications; Eric B Herr, Planning and Development, John W Patten, Sales; Edward E Schirmer. International.

Officers of the Corporation: Harold W McGraw Jr. President. Chief Executive Officer and Chairman of the Board; Robert F Landes. Senior Vice President and Secretary; Ralph J Webb, Treasurer.

In This Issue

Do you have trouble making all the pieces fall in place when you are writing a new program? Robert Tinney's cover this month symbolizes the theme of programming methods. But the symbolism is only pictorial— the process of designing and putting a new program together is often much harder than assembling an intricate jigsaw puzzle. This issue includes several articles on different aspects of programming and design: "What Is Good Documentation?" by Jim Howard; "Structured Programming and Structured Flowcharts" and the editorial, "Is This Really Necessary?", both by Editor Gregg Williams; "A Coding Sheet for FORTH," by John O Bumgarner; and "A Simple Approach to Data Smoothing," by Fred Ruckdeschel and Janice A Krinsky.

BYTE is published monthly by BYTE Publications Inc. 70 Main St. Peterborough NH 03458. a wholly-owned subsidiary of McGraw-Hill. Inc. Address all mail except subscriptions to above address: phone (603) 924-9281. Address subscriptions, change of address. USPS Form 3579, and fulfillment questions to BYTE Subscriptions. POB 590. Martinsville NJ 08836. Controlled circulation postage paid at Waseca. Minnesota 56093 - USPS Publication No. 528890 [ISSN 0360-5280) Canadian second class registration number 9321. Subscriptions are S19 for one year, S34 for two years, and S49 for three years in the USA and its possessions. In Canada and Mexico. S2I for one year, S38 for two years, S55 for three years. S43 for one year air delivery to Europe. S35 surface delivery elsewhere. Air delivery to selected areas at additional rates upon request. Single copy price is S2.50 in the USA and its possessions, S2.95 in Canada and Mexico. S4.00 in Europe, and S4.50 elsewhere. Foreign subscriptions and sales should be remitted in United States funds drawn on a US bank. Printed in United States of America.

Address all editorial correspondence to the editor at BYTE, POB 372, Hancock NH 03449. 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 Entire contents copyright © 1981 by BYTE Publications Inc. All rights reserved. Where necessary, permission is granted by the copyright owner for libraries and others registered with the Copyright Clearance Center (CCC) to photocopy any article herein for the base fee of SI 00 per copy of the article or item plus 25 cents per page. Payment should be sent directly to the CCC, 21 Congress St. Salem MA 01970. Copying done for other than personal or internal reference use without the permission of McGraw-Hill is prohibited. Requests for special permission or bulk orders should be addressed to the publisher.

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March 1981 © BYTE Publications Inc

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ELECTRONIC DESIGN, 1981 Technology Forcast

MICROANGELO

HIGH RESOLUTION GRAPHICS SINGLE BOARD COMPUTER

512 x 480 resolution black and white and vivid color displays

RS-170 composite or direcl. drive output

Local or external sync generation

4Mhz Z80 microprocessor

60 hertz realtime clock

8 level interrupt tie-in

IEEE SI00 bus compatible

Screenware™ Pak I

A 4K byte operating system resident in PROM on MicroAngelo™. Pak I emulates an 85 character by 40 line graphics terminal and provides over 40 graphics commands. Provisions exist for user defined character sets and directly callable user extensions to Screenware™ Pak I.

Screenware™ Pak II

An optional software superset of Pak I which adds circle generation, polygon flood, programmable split screen for separate graphics and terminal I/O, relative coordinates, faster vector and character plotting, a macro facility, full UCSD Pascal compatibility, and more.

Light pen interface

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The new MicroAngelo™ Palette board treats from 2 to 8 MicroAngelos as "bit planes" at a full 512 x 480 resolution. Up to 256 colors may be chosen from 16.8 million through the programmable color lookup table. Overlays, bit plane precedence, fade-in, fade-out, gray levels, blinking bit plane, and a highly visual color editor are standard.

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Editorial

Is This Really Necessary? A First Look at Design Techniques

Gregg Williams, Editor

Complete the following sentence:

When I start programming, the first thing I do is .

Some people draw flowcharts. A few adventuresome—usually foolhardy —souls type in lines of BASIC directly on their computers. Most of us start by scribbling and sketching on sheets of paper. However, is that enough? Perhaps so, if you're writing for yourself; but if anything important is at stake—time, money, or reputation—you probably need to spend more time designing.

In this editorial, I'll show you what design is, why you need it, and how it works. I'll also present some new design tools (of which there are more and more every day), a design example, and a sampling of good books on design and programming. I promise to stay as far away from the concept of "structured programming" as possible. Much has been written about it elsewhere. I want to concentrate on what happens before you start programming.

What Is Design?

Webster's New Collegiate Dictionary defines design, the verb, as "to conceive and plan." As a noun, a design is "a preliminary sketch showing the main features of something to be executed." In terms of programming, design becomes proportionately more important depending on the size of the problem: We speak of program design when we write a game program for ourselves, project design when we design and write an accounting system on an existing computer at work, and system design when we draft a proposal for a hardware/software combination that will implement a given set of requirements for a data base system. (Actually, "system design" is used in the literature to describe the design of anything larger than one program; but I wanted to make a distinction between project design and system design because of the widely varying amounts of work they require.)

In designing and writing programs, I've found that the point dividing system design from program design is the point at which I have specified the function of the program and its use of computer resources (eg: are records stored on disk in a random-access file and called as needed, or are they read into memory before any processing is done?). After this point, I am designing the program (usually a fairly straightforward—though nontrivial—process). Before this point, I'm making certain critical decisions that strongly influence the requirements and performance of the proposed implementation of the program. In this sense, such decisions will often need to be made even when I'm designing and writing a single program. I can then see that both system design and program design have enough in common so I can eliminate the modifier and speak simply of design. I can safely say then that design is concerned with making a set of performance-related decisions and specifying the program(s) that implement them.

(An integral part of design, of course, is documentation. Documentation of the overall design should be followed by documentation of the program design and its implementation. The finished documentation package, which should clarify both the organization of the system/project/program and the details of

March 1981 © BYTE Publications Inc

1* ^ ,

jadstron?^

«

For reliable data storage, you can't beat Shugart's

Minifl

yy M Raymoncj Schlitzer, Owner— Computerland, San Francisco

"I sell systems my customers can depend on.Thars why most of the personal and small business computer systems sold here feature Minifloppy disk drives. I know from experience I can rely on the Minifloppy"

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TM—Minifloppy is a trademark of Shugart Associates.

have been installed.The Minifloppy looks small—but it stores a lot of data. 250 kilobytes on one side, or up to 500 kilobytes in the double-sided model. Thart about 50 pages of printed information on a single-sided Minidiskette, and twice that on the double-sided version.You'll have plenty of storage capacity for your programs, letters, forms, or ledger entries. And you find your data fast, too, because the Minifloppy is a random access device

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No matter what problem you're solving with your computer system, you can rely on Shugart's Minifloppy for data storage. We're known as the Headstrong company for good reason. We're Headstrong about reliability, quality, and value. Ask your dealer. He knows us.

Rely on the Headstrong Company.

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Editorial

the program(s) involved, will be of immense help to you, or anyone else, during debugging, testing, and maintenance.)

To put the role of design in perspective let's look at the lifespan of a medium-sized system:

• (System) Design: This is the step I talk about in most of this article. It includes finding out what the problem is, devising alternative schemes to solve it, deciding on the one that (you think) will result in the "best" implementation, and filling in the design details with regard to the items that go into the system (input), the manipulations made on these items (process), and the results that are generated by the system (output). By the end of this process, you will have divided the entire system into programs and specified the input, process (what, not how), and output of each one.

• Program Design: This is where structured programming is used. You know what the program is supposed to do and what computer resources are to be used; now you must fill in the details of how its objectives are to be accomplished. It is commonly accepted that the best way to design a program is to repeatedly break the task to be accomplished into subtasks, until each subtask is simple enough to be programmed in the language you are using. Note that the design process ends without your having written any lines of computer code. In this step, you are simply filling in the details of what the program is to do without worrying about the particular syntax of the computer language you will use. (There are numerous design notations to help in this process. The two I like most are structured pseudocode, described below, and structured flowcharts, which is described in my article, "Structured Programming and Structured Flowcharts," on page 20 of this issue.)

• Coding: This is what most people call "programming," even though they are referring to the entire design/ coding process. Coding is the specific act of translating a program design into the particular syntax of the computer language you are using (often called the target language). The more detailed the design is, the more coding becomes a rote task. The completeness of the design is determined by several factors. These are: how well you think you know the application being programmed and the computer language used, how important it is to get the program right the first time, and how many surprises (mostly of the "oops, I forgot to..." kind) you can tolerate during

Articles Policy

BYTE is continually seeking quality manuscripts written by individuals who are applying personal computer systems, designing such systems, or who have knowledge which will prove useful to our readers. For a more formal description of procedures and requirements, potential authors should send a large |9 by 12 inch, 30.5 by 22.8 cm), self-addressed envelope, with 2B cents US postage affixed, to BYTE Author's Guide, POB 372, Hancock NH 03449.

Articles which are accepted are purchased with a rate of up to S50 per magazine page, based on technical quality and suitability for BYTE's readership. Each month, the authors of the two leading articles in the reader poll |BYTE's Ongoing Monitor Box or "BOMB") are presented with bonus checks of SI00 and S50. Unsolicited materials should be accompanied by full name and address, as well as return postage.

PASCAL/Z ™- Q.E.D.

Ithaca Intersystems PASCAL/Z is the most powerful CP/M™ compatible Z-80™ Pascal compiler ever . . . and here's why:

PASCAL/Z generates true Z-80 native code — ROMable and re-entrant — 5-1 OX faster than P-code interpreters; permits separate compilation; supports Direct File Access and variable length STRINGs; utilizes fast one-pass recursive descent organization; the macro-assembler generates relocatable object modules; and much, much more.

Complete package includes compiler, macro-assembler, linker/loader and source for the full library on one disk; with free copy of Jensen/Wirth book and complete documentation. Only $395.00.

IT'S DEMONSTRABLE! Don't just take our word for it. Ask for a demonstration of these features and more today at Computerland® and other full-service computer stores.

Ithaca Intersystems Inc., 1650 Hanshaw Road

P.O. Bo» 91, Ithaca, N.Y. 14850. Phone (607) 257-0190

Computerland is a registered trademark of Computerland Corporation.

CP/M and Z-80 are trademarks of Digital Research Corp. and Zilog, Inc. respectively.

PASCAL/Z and InterSystems are trademarks of Ithaca Intersystems Inc.

8 March 1981 © BYTE Publications Inc

Circle 5 on inquiry card.

Intersystems

Micros for bigger ideas.

The InterSystems

price-performance-reliability story

now has three versions

While everyone's been busy trying to convince you that large buses housed in strong metal boxes will guarantee versatility and ward off obsolescence, we've been busy with something better. Solving the real problem with the first line of computer products built from the ground up to conform to the new IEEE S-100 Bus Standard. Offering you extra versatility in 8-bit applications today. And a full 16 bits tomorrow.

We call our new line Series II. And even if you don't need the full 24-bit address for up to 16 megabytes (!) of memory right now, they're something to think about. Because of all the performance, flexibility and economy

they offer. Whether you're looking at one of our three mainframes, at a new mainframe, expanding your present one or upgrading your system with an eye to the future. (Series II boards are compatible with most existing S-100 systems and all IEEE S-100 Standard cards as other manufacturers get around to building them.)

Consider some of the features: Reliable operation to 4MHz and beyond. Full compatibility with 8- and 16-bit CPUs, peripherals and other devices. Eight levels of prioritized interrupts. Up to 16 individually-addressable DMA devices, with IEEE Standard overlapped operation. User-selectable functions addressed by DIPswitch or jumpers, eliminating soldering. And that's just for openers.

The best part is that all this heady stuff is available now\ In our advanced processor —a full IEEE Bus Master featuring Memory Map addressing to a full megabyte. Our fast, flexible 16K Static RAM and 64K Dynamic RAM boards. An incredibly versatile and

economical 2-serial, 4-parallel Multiple I/O board. Our 6-serial I/O board. Our Double-Density High-Speed Disk Controller. And what is undoubtedly the most flexible front panel in the business. Everything you need for a complete IEEE S-100 system. Available separately, or all together in your choice of DPS-1 mainframe styles.

Whatever your needs, why dump your money into obsolete products labelled "IEEE timing compatible" or other words people use to make up for a lack of product. See the future now, at your Intersystems dealer or call/ write for our new catalog. We'll tell you all about Series II and the new IEEE S-100 Bus we helped pioneer. Because it doesn't make sense to buy yesterday's products when tomorrow's are already here.

Ithaca Intersystems Inc.,

1650 Hanshaw Road/RO. Box 91,

Ithaca, NY 14850

607-257-0190/TWX: 510 255 4346

Micros for bigger ideas.

/

BYTE March 1981

Editorial.

coding. In most informal situations (ie: when you're not programming for hire), a sketchy design provides an acceptable compromise between no design and a rigorous design.

Figure 1: A pie chart giving average percentages for activities within the process of designing, writing, and testing a program. The chart does not include maintenance of the program, which is estimated to take twice as much time as design, writing, and testing.

(Let your computer play psychiatrist!)

ANALIZA is a program which simulates a conversation with a psychiatrist. You are the patient, the computer becomes the doctor.

ANALIZA is based on the famous "Eliza" program from MIT some years back, but has been greatly enhanced. It provides both entertainment as well as an interesting example of Artificial Intelligence. Below is a sample:

Patient: I have feelings of paranoia

Computer: Does it please you to have feelings of paranoia?

Patient: No it bothers me

Computer: Then why have feelings of paranoia?

ANALIZA is a match for anyone.

Requires: 48K CP/M, CBASIC2 Cost: $35.00

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CPIM REGISTERED TRADEMARK DIGITAL RESEARCH

• Testing and Debugging: This section is actually two intertwined processes—testing, the search for errors (both syntactic and logical), and debugging, the elimination of those errors. Most programmers estimate that this process can take as much time as both designing and coding. The results in figure 1 (by M V Zelkowitz in " Perspectives on Software Engineering," ACM Computing Surveys, June 1978, page 198) support this conclusion. The amount of needed debugging and testing greatly increases depending on the program's size and importance. It decreases with the amount of design and structured programming carried out before the coding. In a multiprogram system, programs are first tested and debugged (labeled "module test" in figure 1), then the entire system is tested and debugged (labeled "integration test" in figure 1).

• Maintenance: This section applies mostly to large programs for personal use and systems that are used in a work environment. Maintenance runs the gamut from fixing the occasional (or not-so-occasional) bug, to adding new features, or to moving a system of programs to an entirely new computer system. It's been estimated that maintenance occupies up to 90 percent of a (professional) programmer's time. Fortunately, most personal computer users don't have to carry this burden.

Why Designing Is Necessary

Whether we like it or not adventures begin only when something unexpected happens. In fantasy, adventures are always positive and exciting; in real life and in programming, they are usually unwanted, inconvenient, and sometimes costly or dangerous. Only short personal programs can squeeze by without some basic design work behind them. If the program gets longer, or if you are writing for somebody else (either friends or employers), you probably can't afford a programming "adventure." Remember that the design process includes finding and making decisions that influence the quality of a program or system. In other words, the more important it is to write the best program, the more design you need to do.

Here are some reasons that argue strongly in favor of well-thought-out design:

• Limited resources (eg: not enough computer memory or disk space, or a slow system response time)

• Time/money constraints (ie: the need to complete a program or system within deadline and under budget)

• The need for increased reliability

• The need for program stability and flexibility in the face of long-term maintenance

In addition to contributing to the quality and reliability of a program, design also contributes to your mental health as a programmer—you usually save time when you design; you eliminate all-night emergency programming marathons; the process of testing and debugging is shorter and less nerve-racking; and you're less likely to have your program "crash" at an embarrassing or crucial moment.

Some Popular Excuses, and Rebuttals

"I don't know where to start": Read some of the books

Text continued on page 200

10 March 1981 © BYTE Publications Inc

Circle 7 on inquiry card.

Make the Apple II* a powerful IEEE -488 Controller in a snap.

Just plug the SSM A488 board into any Apple II* expansion slot for a low-cost,

full-featured instrumentation interface. SSM gives the Apple II the power and versatility of a $9,000 IEEE-488 controller. At a fraction of the price. Our board converts the Apple II into a truly sophisticated controller that programs and controls up to 15 different instruments connected together on the 488 bus.

We make programming easy. The 68488 chip, designed by Motorola, forms the heart of our A488. We back this chip with powerful on-board firmware to give you system control via simple string commands. The only software you need is easy-to-program Applesoft* Basic. To develop special purpose firmware, simply replace our PROM with a RAM. With the A488, bus communications operate at top speed—without depending on software loops for timing. And like the more expensive IEEE-488 controllers, this system interfaces with more than 1200 instruments and peripherals.

Suitable for OEMs as well as end users. Whether you make test/measurement systems for sale, or simply for yourself, the SSM/Apple combo gives you top performance. As your costs. Call your local dealer or SSM today for complete details.

IEEE-488 bus cable

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Industrial grade circuit board

PROM firmware for powerful user interface 68488 IEEE-488 controller chip

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SSM's A488 board expands the Apple II to a high-performance IEEE-488 controller.

' Registered trademarks of Apple Computer Inc.

SSM Microcomputer Products, Inc.

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Letters

On Technical Writing

I enjoyed Chris Morgan's editorial on technical writing ("What's Wrong with Technical Writing Today?" December 1980 BYTE, page 6), but there is a sad exception to his first law: Academics can benefit from not writing clearly. I suggest a paper by J S Armstrong in the April 1980 Interfaces, published by The Institute of Management Sciences.

Armstrong, from the Wharton School, found that material more difficult to read was rated higher in research competence. "Management scientists gain prestige by unintelligible writing." My wife, an academic biologist, and I have seen similar hypotheses about academic publishing in computer science. {Communications of the ACM may be a perfect example.)

Since such "news" would only undermine the effort you folks are making at BYTE, you must keep all this a secret.

Gerald Ruderman Management Decision Systems Inc 300 Third Ave Waltham MA 02154

In the December 1980 editorial, Chris Morgan says that "Jargon isn't intrinsically bad...."

Ha! I caught you. Jargon is intrinsically bad; it may be necessary sometimes — an evil necessity—but it's always bad. I've often wondered if those who edited BYTE were in favor of jargon. Now I know.

Like many aspects of our society, jargon has two purposes: an obvious one, and a hidden, unadmitted one. The obvious purpose is to save space, as Mr Morgan pointed out. The hidden one is to exclude outsiders from the circle of the insiders.

To use jargon in explaining the workings of a particular product would be justifiable in a manual directed toward sophisticated, knowledgeable professionals, if the product were released in a specific, well-known context. An example is all the funny words people familiar with IBM equipment always use. Such an approach in a journal like BYTE is entirely inappropriate.

The distinctive difference between BYTE and some of its less successful

Introducing

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competitors is that many BYTE articles, even though written in jargon, try to explain something, while too many articles in other magazines use jargon purely for the purpose of mystifying.

Jargon may have many purposes, but the rapid, effective spread of information is not one of them. If you really wish to communicate ideas, write in English—or some common human language.

The balance of Mr Morgan's editorial was actually quite to the point. I'd like to add, "DON'T use big concepts when small ones will do."

James Gregor Owen 14 Ocean Dr Freeville NY 13068

The December editorial apparently struck a nerve among readers, judging from the comments we received. Mr Owen raises a point I did not cover: the "high priesthood" syndrome that arises when a writer sets out to impress and mystify through jargon. At BYTE, we wage a (not always successful) battle against this philosophy, and hope that our readers will continue to tell us when we go astray. I'd also like to thank the editors at General DataComm Industries Inc, Danbury, Connecticut, and several other readers who caught some minor gaucheries in my editorial. Oh, the irony of it....CM

Intel's Educational Products

As the manager of Intel Corporation's Educational Products Group I would like to thank BYTE for suggesting our company as a source for blemished components. Steve Ciarcia's reply to an "Ask BYTE" letter has generated a large response from students and educators. (See "Quick and Cheap," December 1980 BYTE, page 320.) In order to help BYTE's readers to more fully benefit from our program, I would like to bring some additional information to their attention.

The Educational Products Group has the responsibility for the administration of the component kit program. To avoid delays of up to 4 weeks, all inquiries should be directed to us, not the product manager.

We no longer offer an 8080-based kit;

12

March 1981 © BYTE Publications Inc

Circle 8 on inquiry card.

Circle 9 on inquiry card.

Edison had over 1,800 patents in his name, but you can be just as inventive

with an Apple.

Apple is the company with the brightest ideas in hardware and software and the best support — so you can be as creative with a personal computer system as Edison was with the incandescent bulb.

How Apple grows with you.

With Apple's reliable product family, the possibilities of creating your own system are endless. Have expansion capabilities of 4 or 8 accessory slots with your choice of system.

Expand memory to 64K bytes or 128K bytes. Add an A to D conversion board. Plug into time sharing, news and electronic mail services. Use an IEEE 488 bus to monitor lab instruments. Add 4 or 6 disk drives — the 5lA" 143K bytes, high-speed, low-cost drive that's the most popular on the market.

Apple speaks many languages.

Since more than 100 companies create software for Apple, you'll have the most extensive library in the personal

computer world. Want to write your own programs? Apple is fluent in BASIC, Pascal, FORTRAN, PILOT and 6502 assembly language.

There's even a series of utility programs called the DOS Tool Kit that not only lets you design high-resolution graphic displays, but lets you work wonders with creative animation.

More illuminating experiences in store.

You won't want to miss all the Apple products being introduced at your computer store all the time. Don't let

A history pass you by. Visit your nearest .^fejEfe. Apple dealer or call 800-538-9696. In California, 800-662-9238. Or write: ^ Apple Computer, 10260 Bandley Drive, ^ Cupertino, CA 95014.

cippkz computer inc.

Letters ..1.—.———————

instead we offer a broad line of kits based upon the 8085, 8048, 8086, and 8088 microprocessors. The 8086 and 8088 kits include a serial monitor. Kit prices range from $35 up to $90, and each contains enough components to construct a minimum system.

Intel is in the process of expanding the program, and we publish a quarterly magazine to let prospective members of the academic community know of these developments.

Please contact us if you would like more information on how we can help you. Our telephone number is (408) 987-5020.

Steven A Lapham

Manager, Educational Products

Intel Corporation

3065 Bowers Ave

Santa Clara CA 95051

Intertec Responds to Criticism

In response to Mr Phillip Lemmons's letter (see "Superb Brain," October 1980 BYTE, page 22), I would like to make the following observation. We at Intertec disagree with his analysis of the situation and feel that clearing up the facts

would be a benefit to Intertec and our users alike.

Everyone must realize that nothing remains static in the computer industry. New ideas constantly emerge, resulting in a stream of new developments. The continual upgrading of technology, and the subsequent evolution of computer software and hardware, is the basis of high technology as all of us know it today. As responsible manufacturers, we feel obliged to pass on these technological advancements to our users.

As improvements are added to our products, we offer our previous customers, whenever feasible, an upgrade option at nominal cost. If the modification cannot be accomplished with a simple EPROM change, for instance, we still feel a responsibility to offer some kind of solution to our customers.

Such is the case with Mr Lemmons's "$1500 enhancement." The modifications to which he refers involved changing the whole unit: processor module, power supply assembly, disk drives, etc. In January 1980, the SuperBrain was modified to offer even more capabilities than our advertisements claim. Therefore, had Mr Lemmons purchased this enhancement, he would, in effect, have

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Olddata Microline 80 599.00

Diablo 630 2495.00

MISC HARDWARE

Expansion in TRS80(Olt) 249.00

Novation D-Cat Modern 166.00

I t>l< Memory Kit 41.99

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Printer Cable for above . ... 49.00

ISO 2 Isolator 54.00

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Scotch-box 10-514 27.00

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OPERATING SYSTEMS

NEWDOS by APPARAT INC 49.00

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MMS FORTH DISKETTE PRIMER 79.95

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Free enhancements and upgrades to registered owners lor the cost ol media and mailing 30 day Iree telephone support User reference on request Fully Interactive Accounting Package. General Ledger,

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Complete Package (requires 3 or 4 drives) 5475.00

Individual Moduleslrequires 1 or 3 drives) 51 25.00

Inventory II (requires 2 or 3 drives) $ 99.00

Mailing List Name 6. Address II

(requires 2 drives) $129.00

Intelligent Terminal System ST 80 III 5 1 50.00

TheEleclnc Pencil f torn Michael Shrayer 5150.00

file Management System $ 49.00

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received a completely new unit for $1500—half the end-user cost for the same unit.

As for the software problem Mr Lemmons referred to, we are confident that an EPROM update costing $100 would have taken care of his problems. Mr Klein of Information Engineering sold it to him for $150. Admittedly, Mr Lemmons may have received this update a little sooner than he would have had he purchased directly from the factory; nevertheless, the EPROM is available from us.

For an end-user price of $2995 for our basic SuperBrain model, we think (and we have thousands of testimonials from happy SuperBrain users to support this) that Intertec offers the best price/performance ratio in the industry.

If any other BYTE readers have problems similar to Mr Lemmons's, please call our Product Services department at (803) 798-9100. Our staff of application engineers will be glad to assist you in any way possible.

At Intertec, the customer has always been (and still is) our main concern. Our phenomenal growth in recent years would not have been possible if we did not hold steadfastly to this simple management principle. We hope Mr Lemmons (and any others who may be dissatisfied with us) will understand our point of view and give us a chance to demonstrate the sincerity of all of our customer-support programs.

Denise Stevens

Marketing Communications Manager

Intertec Data Systems

2300 Broad River Rd

Columbia SC 29210

Hurray for muSIMP

I recently purchased muSIMP/ muMATH for my Radio Shack TRS-80 Model I, so I was interested in Gregg Williams's review in the November 1980 BYTE. (See 'The muSIMP/ muMATH-79 Symbolic Math System," page 324.) The version I purchased is the small, inexpensive TRS-80 version, which does not include the trace, array, and matrix packages.

While the discussion of muMATH was complete, I was disappointed that Mr Williams only touched briefly on the capabilities of the underlying muSIMP language used to implement muMATH. The introduction of a low-cost version (or any version) of LISP for the TRS-80 should be marked as a major development. muSIMP is a close cousin of LISP, and, in this light, muMATH is seen as a powerful illustration of its capabilities. The impressive achievements of muMath

14

March 1981 © BYTE Publications Inc

Circle 10 on inquiry card.

Introducing the COLOR CONNECTION

Plug A TRS-80* Color Computer into the World of System-50" Computing.

Now you can expand Tandy's exciting new TRS80* Color Computer using proven System-50 products. Expansion possibilities are limitless. And expansion is easy. Plug one end of the COLOR CONNECTION into the Program Pak* connector of the Color Computer. Plug the other end into a System-50 bus motherboard. Now add the functions you want, selecting from an inventory of standard modules manufactured by competent, long-established firms — from the inventory of solid performers, like Percom Data Company.

Mini-disk storage — today!

Available off-the-shelf for your extended system is Percom's fieldproven LFD mini-disk system. The first choice of knowledgeable 680X computerists since 1977, Percom LFD mini-disk systems come complete, ready to plug in and run. File storage capacities range from 102 Kbytes for a one-drive LFD-400™ system to almost 0.6 Mbyte for a three-drive LFD- 800™ system.

Get serious!

For serious computing like word processing add the Percom ELECTRIC WINDOW™. This memory-mapped video display card features instant display updating, softwaredefined full display formatting — up to 80 characters by 24 lines, an extendable character generator that generates fullyformed upper and lower case characters, and more. The ELECTRIC WINDOW provides either composite or separate sync-video output, and interfaces a standard black-&white video display monitor.

System Requirements

The COLOR CONNECTION interfaces a TRS-80* Color Computer to a System50 bus motherboard. Power for the COLOR CONNECTION is obtained from the computer. Power for the extended bus cards must be provided by an external source, such as Percom's System-50 Power Supply. The COLOR CONNECTION provides for disabling the computer internal memory at 8-Kbyte boundaries to prevent contention with external memory.

The COLOR CONNECTION $99.95

Beyond 16K

Another option is incremental memory expansion. Add 8-, 16- or 24-Kbytes of static RAM with our M24SS card; 16-, 32- or 48-Kbytes of dynamic RAM with our M48DSS card. The COLOR CONNECTION prevents contention between internal computer memory and external memory.

The right motherboard

Fast mini-disk storage, full-format alphanumerics and memory add-on are obvious expansion possibilities. The optional Percom System-50 Motherboard allows you to consider the less obvious. This seven-slot motherboard not only can be self-extended, but also can be extended with our 30-pin I/O motherboard. The richness of readily available peripheral interface cards provides an uncommon degree of expansion flexibility.

The System-50 (SS-50) bus community. With a TRS-80* Color Computer and the COLOR CONNECTION, it's your world. Enjoy!

Quality Percom products are available at Percom dealers nationwide. Call toll-free, 1-800-527 1592. for the address of your nearest dealer, or to order direct from Percom.

PRICES AND SPECIFICATIONS SUBJECT TO CHANGE WITHOUT NOTICE. PRICES DO NOT INCLUDE SHIPPING AND HANDLING.

™ trademark of Percom Data Company. Inc.

* trademark of Tandy Radio Shack Corporation which has no relationship to Percom Data Company.

PERCOM DATA COMPANY, INC.

211 N. KIRBY GARLAND. TEXAS 75042 C214) 272-3421

Circle 11 on inquiry card.

Letters _^^—__

have overwhelmed the fact that muSIMP is a general language suitable for more than symbolic mathematics applications. The differences between muSIMP and LISP are mostly at the user interface. The input syntax and the output format have been altered to provide a congenial environment for symbolic mathematics, but internally muSIMP is LISP with only a few minor alterations (which could well be regarded as improvements over the original). These alterations are summarized in "LISP-Based Symbolic Math Systems" by David R Stoutemyer, which appeared in the BYTE LISP issue of August 1979, page 176.

At $75 (plus another $20 for the complete reference manual) muSIMP for the TRS-80 is a great bargain. Yet Microsoft's ads have pushed muMATH with only a passing reference to muSIMP's close relationship to LISP.

The documentation that comes with the TRS-80 version of muSIMP/ muMATH does not include a number of important muSIMP functions. For example, the functions related to property lists are not even mentioned. Propertydriven functions are a major component of muMATH's power and extensibility. The TRS-80 owner who wants to explore the power of muSIMP definitely

needs to purchase the full reference manual to supplement the material that accompanies the package.

The full reference manual is impressive. It includes listings of on-line tutorials apparently available with the larger CP/M version. Unfortunately, it does not specifically address the system environment of the reduced TRS-80 package. A number of system functions are not included (SAVE, LOAD, OBLIST). While the manual is extremely useful to the TRS-80 owner, it would be even more useful if it included a summary of the differences between the full CP/M version and the reduced TRS-80 version.

In short, for the TRS-80 owner who is interested in experimenting with artificial intelligence projects, muSIMP alone is worth the price of the muSIMP/ muMATH package.

John R Goldin 66 Brownell St New Haven CT 06511

BYTE Saluted

I am a career Army officer. After five years of assignments outside of the data

processing field, I have returned to that arena; however, the landscape has changed. It is covered with new technology, methods, technical terms, and jargon.

I want the world to know how useful BYTE is in overcoming the insecure feeling of operating in this new landscape. Particularly noteworthy and helpful is BYTE's editorial policy of parenthetically explaining all jargon and technical terms. While other trade journals seem to take delight in obscurity, BYTE consistently targets on clarity. I hope other publications will follow BYTE's lead. It's needed.

Keep up the good work, BYTE!

James H Powers

Lieutenant Colonel, US Army

Director, ADP (Automatic Data Processing)

Support Division US Army War College Carlisle Barracks PA 17013

Self-Replicating Code

I would like to point out the shortest self-replicating program I know of. It is written in Microsoft BASIC, as found in the Commodore PET (also known as the

A REFURBISHED "SELECTRIC" ASCII TERMINAL FOR THE SMALL BUSINESSMAN OR SERIOUS HOBBYIST

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16

March 1981 © BYTE Publications Inc

Circle 12 on inquiry card.

Circle 13 on Inquiry card.

ew muscle

tor Heathk it

Now with new CPI

new

8-inch disk system for millions more bytes.

The Heathkit All-in-One Computer now has space for 64K of addressable RAM, so you can run bigger, more complex programs.

And our new CP/M""' Operating System (Standard ORG-0, Version 2.2) makes thousands of CP/M programs available to you. Heathkit systems can run more, do more, store more than ever before. A new 8-inch double-sided, double-density disk system, with over 1 million bytes per drive, is now available for Heathkit H-89 and H-8 Computers. The new 8-inch disk system features soft-sectored disks for IBM'"' compatibility. It's capable of operating in standard IBM 3740 format. And the 8-inch sys

VISIT YOUR HEATHKIT STORE

Heathkit products are displayed, , —

sold and serviced at Heathkit

Electronic Centers*, located in

major cities throughout the U.S.

and Canada. See your white

pages for the store nearest you.

"Units of Veritcchnology Electronics Corporation, in the U.S.

tern can be used in conjunction with 51/4-inch systems. For compatibility with the rest of the industry, Heathkit Computers may just be the most flexible systems you can buy.

All Heathkit computers and peripherals are available in money-saving, easy-to-build kit form —or completely assembled and factory tested. All are supported by the best documentation in the business and by 62 service centers throughout the U.S. and Canada. You're never out in the cold. For complete details and prices on Heathkit computers, peripherals and software, write today for the latest Heathkit Catalog or visit your Jtikif I nearby Heathkit Electronic Center*.

*"" Send for FREE catalog

Write to Heath Company, Dept. 334-754, Benton Harbor, Ml 49022

In Canada, contact Heath Co., 1480 Dundas St. E., Mississauga, Ontario L4X 2R7

Heathkit

IBM is a registered trademark of International Business Machines Corporation. CP/M is a trademark of Digital Research, Inc.

Circle 14 on inquiry card.

THE

UfilVERSf

~ AT YOUR:^*

FINGERTIPS

TellStar

for the Apple It

Choose a'date, time, and place on Earth and let TellStar display the Stars, Planets, Sun, Moon and fascinating Stellar Objects in High Resolution Graphics. _

With interactive commands,' TellStar enables yo'u to easily locate andMdentify stellar objects. Right Ascension, Declination, > Azimuth, EleVation, Rise and Set Times are presented adjusted for precession. Planetary data is calculated using Kepler's equations. Constellations are drawn before your eyes. Print High Resolution Graphics displays on a Silentype. Scientific data can be printed on any printer.

A Calculation Utility is provided for equatorial, ecliptic, horizontal, and precession conversions.

TellStar Level I on disk $39.95 Northern Hemisphere Star Tables

TellStar Level II on disk $79.95 Comprehensive 47 page manual Northern Hemisphere Star Tables Southern Hemisphere Star Tables Messier Object Star Tables

Visit your local computer store for demonstration orwriteformore information.

Address. City

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Information Unlimited Software, Inc.

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TellStar is a trademark of Scharf Software Services.

Apple is a trademark of Apple Computers. Inc.

Letters,

CBM 2001). It relies on the fact that PET BASIC sees all commands the same way. In many BASICs, you can write a 1-line instruction without a line number and it will be executed when entered. But PET BASIC also allows commands like RUN or LOAD to be inserted into a program with a line number, like any instruction. The program is:

1LIST

Because of the compact storing of code in the PET's memory, the program takes up only 2 bytes, one for the line number, and one for the PET's internal representation of LIST (the space between is provided by the subroutine that controls the printout of integers).

I'm currently in the 9th grade, and am fluent in BASIC. I intend to learn Pascal when the school library gets the book it just ordered.

William Sommerfeld 3 Mary Ln Greenvale NY 11548

Printers Challenged

For some months now, I have been searching for a printer that meets all of my needs, and have met with little success. I have lost hope of finding what I want by looking at magazine advertisements, visiting computer stores, and circling numbers on reader-service cards. I would like to issue this challenge:

If any printer manufactuer or distributor has a machine that fits all (and I mean all) of the requirements listed below, I will buy it, pure and simple.

• It must have some form of letterquality printing. A fast, low-quality mode and a slow, high-quality mode would be fine. ("Letter-quality," as far as I am concerned, means lowercase letters with descenders.)

• It must be able to handle both singlesheet and fanfold paper (with either pin or tractor feed).

• It must have graphics capability. I can write the graphics software if I must, but the graphics must be real, not block graphics or plotting of Xs.

• It must have at least some minor forms control. Even a simple top-of-page for 11-inch paper would be sufficient.

• I must have some convenient way to get the printer fixed when it breaks. I live in Brooklyn; a service center any

where in the New York City metropolitan area would be fine.

• The printer should cost $1000 or less. The highest I am willing to go, including tax, shipping, and all the options I need, is $1200.

Are all these requirements unreasonable? I don't think so. There are a number of printers advertised in BYTE that miss by only one or two points. For example, MPI's 88G printer does not have lowercase descenders and the closest place 1 could have it repaired is in Ridgewood, New Jersey; otherwise, I would have purchased it right away. The Centronics 737 has no graphics (no Centronics I know of does). Okidata's Slimline cannot handle single sheets, while their Microline has no descenders and only block graphics. The Base2 prints in dark-blue ink and can't handle single sheets either, neither can the Anadex GraphicsPLUS... and so on.

I suppose printer manufacturers have their own reasons for not including this capability or that feature in their printers, but I have a pretty good reason for wanting the features I want. I don't do just one thing with my computer, I do a whole range of things, from business writing to hobbies to simulations to music synthesis. I refuse to invest in another printer that does not help me use my computer to its greatest potential.

Bill Seligman 667 Rugby Rd Brooklyn NY 11230

Run Down

Being a Hewlett-Packard fan and owning an HP-41C, I was anxious to read Bruce D Carbrey's review of the calculator in the December 1980 BYTE. (See "A Pocket Computer? Sizing up the HP-41C," page 244.) I feel that the review was quite good and that all of Mr Carbrey's judgments were fair and realistic, especially when comparing it with Texas Instruments' TI-59.

However, I must disagree with one of Mr Carbrey's observations. He said that the typical life-span of the nonrechargeable size-N batteries is 1 to 2 months. I have had my calculator for 13 months, and I have used it a good deal during that time. Only a week ago did it become necessary to replace the original set of batteries.

Fred W Scheifele 108 Shelly Ln Delran NJ 08075 ■

18 March 1981 © BYTE Publications Inc

Circle 15 on inquiry card.

Mountain Computer makes

more peripherals for

the Apple Computer

than Anybody.

and ... a place to put them

INTROLX-10

software package. Home security with random scheduler. Power usage accounting package for home energy cost control. No wiring required.

APPLE CLOCK

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i

Interrupts -peration of two programs simultaneously. Battery back-up. ' .001% accuracy. Onboard i from BASICs. Supports

SUPERTALKER SD200

room, or sound effec as well as output is ui

grams. I/O capability npted inputs. Use output for ,. announcements in a controlrams. Easy to use because input lecial software operating system.

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Structured Programming and Structured Flowcharts

Gregg Williams, Editor

BYTE

POB 372

Hancock NH 03449

Structured programming — that phrase, unfamiliar to me and, I assume, to most people several years ago—is now endowed with such magical powers that most books on programming include it somewhere in their titles.

But what is structured programming? Most of us feel that it is probably good for us, like getting regular exercise or brushing our teeth after each meal. You may also think it's too complicated (not true), that it slows down programming (wrong, it usually speeds it up), or that it cannot be done unless your computer runs a language like Pascal or ALGOL (wrong again).

Simply put, structured programming is a set of techniques that makes programs easier to write, easier to understand, easier to fix, and easier to change. These techniques are simple and general and can be adapted to any computer language that has a goto statement — that includes BASIC, assembly language, FORTRAN, and COBOL. The purpose of this article is to show you a new form of notation that will help you write structured programs. But first, let's review structured programming.

The Elements of Structured Programming

A structured program is like a set of notes written in outline form. The headings accompanied by Roman numerals—I, II, III, and so on—provide the overall organization. Each Roman numeral topic is broken into several component topics (A, B, and C, for example) and each of these is subdivided further (1, 2, 3, ...) and further (a, b, c, ...) as needed. Table 1

shows a problem and its solution written in this outline form.

The above example demonstrates a process known as decomposition: breaking a task (problem) into its subtasks. This process represents the most important concept in structured programming, ie: that a problem can be solved by repeatedly breaking it into subproblems, until every subproblem can be solved. If you plan this decomposition before you try to write it out in the narrow, precise, and time-consuming syntax of the target language (ie: the programming language you use to solve the problem), you will have a better chance of getting your program right the first time.

It has been

mathematically proven

that any program can

be written using three

basic constructs.

But how do you decide which way to break the problem into subproblems? Common sense helps. Ask yourself, "What sequence of actions and decisions would I have to make if I were doing this without a computer?"

The rest of the answer comes from the literature of structured programming. It has been mathematically proven that any program can be written using three basic patterns, called programming constructs (or simply constructs): sequence, if...then...else, and while...do. The first construct, sequence, gives you the basic capa

bility of breaking a task into a set of subtasks that accomplish the main task when executed sequentially.

The second construct, if...then... else, performs one of two subtasks, depending on the truth or falsity of a stated condition. An everyday example of this construct is given in the following sentence: "If it is raining outside, I will take my umbrella with me; if it is not, I will leave the umbrella at home."

The third and least familiar construct, while...do, is actually a generalized do-loop that repeats a set of actions (called the body of the loop) while a stated condition is true. You use this construct when making iced tea from a mix: "As long as (while) the mix is not completely dissolved, I will continue to stir it."

If you combine lines of code in the three ways described above, the resulting program is said to be structured. In most languages (BASIC, for example) you will still use goto statements, but they will be restricted to carrying your program to specific points, ie: the beginnings and ends of tasks or subtasks. Each module (subtask) in a structured program has a property known as "one-in, one-out"; that is, there is only one entrance and one exit from these modules, and no module will ever jump into the middle of another one. Instead of being like a plate of spaghetti, a program is more like a string of pearls (with each pearl containing another, smaller string of pearls, and so on); each module has a definite and unchanging position on the string. When such regularity can be counted on, existing modules can be changed or deleted, and entirely new modules can be add

20 March 1981 © BYTE Publications lnc

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Structured Programming: A Qualification

About a year ago, I thought that structured programming was the ultimate tool in the analysis, design, and implementation of a computer program. I had read several books on the subject, browsed through a great many more, and successfully applied the techniques to real-world problems. Many books spoke of structured design, but I saw the concept as simply the same structured programming tools applied to the earlier process of program design—that is, of transforming a situation to be solved into a set of programs that will accomplish the task. I was more wrong than right.

Through my experience with a particular programming project, I suddenly recognized a major point that I had formerly not comprehended: that structured programming does not encompass the entire process of programming. The

process of programming begins with some sort of description or specification of the program to be w ritten. With small programs (the kind we spend most of our lives writing), this is usually enough. But as the problem gets bigger (and perhaps more ill-defined), more and more crucial design decisions must be made before you divide the problem into programs.

I also learned that certain design decisions within a given program are overlooked by the main ideas of structured programming. Structured programming is a literalminded discipline that deals exclusively with the orderly disassembly of a problem into the series of program statements that solves it., It does this while assuming several givens: the overall algorithm to be used (eg: bubble sort or heapsort), the data structures used (eg: linked lists, arrays, or binary trees), and implementation details (eg: sequential or ran

dom-access files, the packing of one or two characters per byte). These details, which may have a tremendous effect on the quality of the program (in such aspects as size, speed, readability, and maintainability), are factors that are evaluated and weighed in the design process.

The purpose of these paragraphs is two-fold: first, to affirm that the techniques described in this article can make a significant improvement in your skills as a programmer and that they are sufficient for many programs; and, second, to emphasize that the quality of a program can often be greatly improved by attention to the design decisions that are made in the early stages of analyzing the program design. I am including a list of particularly helpful books and articles in the references at the end of this article.

ed without problems caused by unexpected module interaction.

That is the theory of structured programming—now for putting it into practice. Figures 1 thru 3 show the three constructs (sequence, if... then...else, and while...do) in standard flowchart form and as BASIC code. (For a more detailed look at writing structured programs in BASIC, see 'Applied Structured Programming," listed in the references. This article appears in an anthology that contains several other good articles on program decomposition—

sometimes called top-down design or programming by stepwise refinement—and structured programming.)

The Origins of a New Notation

When I got my first job as a commercial programmer, I realized that I was going to have to write longer programs than I had previously written. This prompted me to adapt structured programming techniques to my work in BASIC, COBOL, and RPG II. (As it turned out, my longest program was a 35-page COBOL program that grew to 75 pages without going

Problem: Given a numeric array V with N elements, find the largest element, MAXV, and its index, MAXINDEX. These variables are related as follows:

• 1 < MAXINDEX < N

• MAXV = V (MAXINDEX)

• MAXV is the largest value in V(1), V(2),...V(N).

Table 1: A problem and its solution in outline form. The common outline form used for summarizing a body of material can also be used to give structure to the emerging design of a program. Table la gives a statement of the problem and table lb gives its solution in outline form.

Solution:

I. Set problem up:

A. Set MAXVAL = -9x 102°

B. Set MAXINDEX = 0

C. Set INDEX = 1

II. Find largest element:

A. Set up a loop that increments the variable INDEX from the beginning to the end of the array V. For each valueof INDEX:

1. Compare the current array value ( V

(INDEX)) to MAXVAL:

a. if MAXVAL is equal or larger, do nothing;

b. if MAXVAL is smaller, replace MAXVAL with the current array value and MAXINDEX with the current index (the value of INDEX).

III. Print the largest element(MAXVAL)and its index (MAXINDEX).

out of control. I could not have done this without the rigorous use of structured programming techniques.)

As my programs grew larger, I became dissatisfied with the methods I used to plan my programs. Conventional flowcharts obscured the structure of my programs. Nassi-Schneiderman charts and Warnier-Orr diagrams were unsatisfactory for other reasons.

The best solution offered in structured programming texts was structured pseudocode, an informally written Pascal-like "program" that uses terse English phrases to describe the program. Listing 1 shows the structured pseudocode for the program outlined in table lb. I used structured pseudocode extensively to outline programs but found that the details of the resulting pseudocode often obscured the overall design of the program.

In retrospect, I can see that I wanted a design notation that could do the following:

• Completely describe the algorithm to be programmed

• Provide overview and detailed documentation that was easy to read

• Not need to be redrawn every time

Text continued on page 26

22 March 1981 © BYTE Publications Inc

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Listing 1: A structured pseudocode solution of the FINDMAX problem given in the text and in table 1, Structured pseudocode is a terse, informal, Pascal-like program that helps the user design a program before writing it in a formal programming language.

Program FINDMAX:

Initialize system variables (MAXV = -9 x 102°, MAXINDEX = 0, INDEX = 1)

While INDEX < N

find value of current array element ( CURRV = V (INDEX) );

if current array element (CURRV) > maximum element so far (MAXV) new maximum element = current element new maximum index = current index ( MAXINDEX = INDEX )

endif

increment INDEX by 1 endwhile

print MAXV, MAXINDEX (end of program)

Listing 2: A BASIC implementation of the FINDMAX problem from table 1. In this program, the variable MAXINDEX has been shortened to MINDEX to distinguish it from the variable MAXV. This program is written in TRS-80 Model I Level II BASIC, and it will run on other computers that use Microsoft BASIC.

lOO 110 120 130 140 150 160 170 180 1 90 200 210 220 230 240 250 260 270 280 290 300 310 320 330 340 350 360 370 380 390 400 410 420 430 440 450 460 470 480 490 500 510 520 530 5 40 550 560 570 760 770 780 790 800 810 B20 830 B40

REM

REM REM REM REM

REM REM

PROCSRAI'I FINDMAX

THIS PROGRAM TAKES AN ARRAY OF NUMBERS, V, AND FINDS THE LARGEST ELEMENT, MAXV, AND ITS INDEX,, MAXINDEX, SUCH THAT:

MAXV = V (MAXINDEX)

(FOR THE PURPOSES OF ILLUSTRATION, WE WILL ASSUME THAT THE DATA IS ALREADY IN THE ARRAY V.)

REM ===========

DIM V(12 > GOSUB 800: REM REM

MAIN PROGRAM

-NOT PART OF ALGORITHM IN FIGURE 6; THIS SUBROUTINE ENTERS DATA INTO ARRAY V

REM

BOX 1: INITIALIZATION ROUTINE

MAXV = -9 * 10[20 MINDEX = 0 INDEX = 1

REM

BOX 2: FIND LARGEST VALUE

REM — (BEGINNING OF WHILE...DO LOOP) IF INDEX > N THEN 520 CURRV = V (INDEX)

IF CURRV < MAXV THEN 440

MAXV = CURRV: REM (THIS PART EXECUTED IF FALSE)

MINDEX = INDEX

INDEX = INDEX + 1

REM — (JUMP TO BEGINNING OF WHILE...DO LOOP) GOTO 370

REM

BOX

PRINT FINAL VALUES

PRINT:

PRINT

PRINT

PRINT "THE LARGEST VALUE IN THE V ARRAY IS: V<"; MINDEX ; ") = "; MAXV

END

REM ============== END OF MAIN PROGRAM

REM SUBROUTINE TO FILL V ARRAY

DATA 12: REM — (NUMBER OF ITEMS TO BE READ IN)

DATA 1, 15, -28, 3.24, -17.92, 0, 5, 1, 0, 21.4,

RE«D N

FOR 1=1 TO N: READ V(I): NEXT I

RETURN

-205, 17

24

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Text continued from page 22:

a change was made in the flowchart

• Use a minimum of unfamiliar notation

• Be visually pleasing

This structured flowchart notation, which I developed over a period of several years, meets these criteria.

Basic Constructs in Structured Flowcharting

According to the tenets of struc

(a)

SUBTASK 1

tured programming, any program can be expressed as a combination of four basic building blocks. These are sequence, if...then...else, while...do, and decomposition. (The first three constructs, described in '""'ventional flowcharts in figures la thru 3a, are given in structured flowcharts in figures 4a, 4b, and 4c, respectively.) The sequence construct (figure 4a) is identical for both conventional and structured flowcharts; however, a later construct, decomposition, will distinguish the structured flowchart sequence construct from its conventional counterpart.

SUBTASK 2

(b)

SUBTASK 3

100 (BASIC statement for subtask 1) 110 (BASIC statement lor subtask 2) 120 (BASIC statement for subtask 3)

Figure 1: Sequence as a control structure. Figure la shows how a linear sequence of subtasks is drawn using conventional flowchart notation. Figure lb shows the equivalent sequence as a series of BASIC lines.

(a)

^condition) .>

Tf

SUBTASK DONE IF CONDITION IS FALSE

SUBTASK DONE IF CONDITION IS TRUE

'

\

'

(b)

(a) CONVENTIONAL

100 IF (condition) THEN 200 120 (BASIC statements for subtask done if condition is false)

190 GOTO 300

200 (BASIC statements for subtask done if condition is true)

299 (last statement of "true" subtask)

300 (first statement of next construct)

Figure 2: The if...then...else construct as a control structure. Figure 2a shows the conventional notation for this construct, while figure 2b shows the BASIC equivalent.

26 March 1981 © BYTE Publications lnc

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(a) CONVENTIONAL

(b)

100 IF (opposite of condition) THEN 300 110 (BASIC statements for body of loop, done if condition is true)

299 GOTO 100

300 (first statement of next construct)

Figure 3: The while...do loop as a control structure. Figure 3a shows the while...do loop in conventional flowchart notation. Figure 3b shows the equivalent loop in BASIC code.

SUBTASK 1

SUBTASK 2

SUBTASK 3

to

SUBTASK DONE IF CONDITION IS TRUE

SUBTASK DONE IF CONDITION IS FALSE

(b)

WHILE (CONDITION)

(c)

BODY OF LOOP

Figure 4: The basic structured flowchart notations. Figure 4a shows the structured flowchart notation for a sequence of tasks; it is equivalent to the flowchart of figure la. Figure 4b shows the structured flowchart notation for the if...then...else construct (equivalent to figure 2a); note that it is the placement of the letters T and F (for true and false) that determines the conditions under which a given subtask is performed. Figure 4c shows the structured flowchart notation for the while...do construct (equivalent to figure 3a); the diagonal line leading down indicates that the condition (in the hexagon) is performed before the body of the loop.

The if,.. then... else construct is fairly straightforward in the conventional flowchart (figure 2a). In the structured flowchart version (figure 4b), the boxes to be performed are to the right of the decision diamond, with the understanding that only one of the two boxes will be performed based on the value of the condition in the diamond. If the "else" side of the

construct is not needed, the box labeled F is eliminated. In this case, if the condition does not evaluate to true, no action is performed, and control continues with the next construct following the decision diamond.

The notation for the while...do construct is not as easily derived. The conventional flowchart cannot directly express this kind of loop; it must

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1601 Orangewood Ave. / Orange, Calif. 92668 (714) 633-4460 TWX / TELEX: 678 401 TAB IRIN

TASK X

SUBTASK

1

SUBTASK

2

\T

jT IF

SUBTASK 3a

'F

SUBTASK 3b

/ WHILE \ B>Y

X

*

SUBTASK 4

SUBTASK

5

Figure 5: Example of the subdivision of a task. A central rule of structured flowcharts is that any box can be broken into multiple boxes that represent the necessary subtasks. Here, task X is broken into five subtasks executed in top-to-bottom order. Subtasks 1, 2, and 5 are simple subtasks. Subtask 3 is an if...then...else construct. Subtask 4 is a while...do loop.

listed in the hexagon is true. The condition is performed first (denoted by the position of the hexagon being spatially above the box being performed); this allows the possibility of the body of the loop being performed zero times if the condition is initially false.

The fourth and pivotal construct of this programming notation, decomposition, can best be stated as a rule: any box representing a task can be broken into multiple boxes that represent the necessary subtasks. The subtasks may be rectangular boxes that represent simple tasks, or they may be any other valid structured flowchart construct (if ...then...else, while...do, etc). They are written top to bottom in the order of performance, with the line denoting program flow entering each subtask box from its top and exiting from the bottom.

Figure 5 illustrates the above construct. Task X is composed of five subtasks performed in numeric sequence. Tasks 1, 2, and 5 are simple subtasks. Subtask 3 is an if...then... else construct that allows either subtask 3a or subtask 3b to be per

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30

March 1981 © BYTE Publications Inc

Circle 21 on inquiry card.

I.tlill Iq atari

'•••J

Atari & A

ilc" softwa:

A financial VP in Massachusetts is cutting the time it takes to prepare month-end reports from three days to three hours.

A California company is replacing most of its time-share computer service with a personal computer and VisiCalc, saving at least $30,000 the first year.

Thousands of other personal computer users are also sold on how VisiCalc is increasing their productivity. Besides saving time and money, they're simplifying their work and getting more information that helps them make better decisions. A typical user reaction comes from a New York dentist:

"VisiCalc has become an integral part of my business''

VisiCalc displays an "electronic worksheet" that auto matically calculates nearly any number problem in finance, business management, marketing, sales, engineering and other areas. The huge worksheet is like a blank ledger sheet or matrix. You input problems by typing in titles, headings and your numbers. Where you need calculations, type in simple formulas (+,—, X, -=-) or insert built-in functions such as net present value and averaging. As quickly as you type it in, VisiCalc calculates and displays the results.

"I am extremely impressed with VisiCalc's capability, flexibility and orderly presentation of instructions!'

So writes the director of a NewYork corporation. He appreciates VisiCalc's powerful recalculation feature. Change any number in your model and instantly all numbers affected by that change are recalculated and new results are displayed. You can ask "What if.. X', analyzing

Commodore is a registered trademark of Commodore Business Machines Inc., Atari is a registered trademark of Atari Inc., Apple is a registered trademark of Apple Computer Inc.

more alternatives and forecasting more outcomes. It really increases your decision-making batting average!

When you finish, you can print a copy of the worksheet just as it appears on the screen and/or save it on diskette.

"I like VisiCalc's ease of use'.'

That response comes from a Utah businessman using VisiCalc for production forecasts, financial report ratio analysis and job cost estimating. Ease of use is VisiCalc's best-liked feature. It's designed for a non-programmer, and has an extensive, easyto-understand instruction manual.

Users also like solving a wide variety of problems with VisiCalc . . . and solving them their way. VisiCalc can even justify the cost of a personal computer, according to a New Hampshire financial analyst:

"VisiCalc is paying for itself over and over."

VisiCalc is available for 32k Commodore PET/CBM, Atari 800 and Apple disk systems. VisiCalc is written by Software Arts, Inc.

See VisiCalc at your Personal Software dealer. For your dealer's name, call Personal Software Inc. at 408-745-7841, or write 1330 Bordeaux Drive, Sunnyvale, CA 94086:

While there, see our other Productivity Series software: Desktop Plan and CCA Data Management System. They're like time on your hands and money in the bank.

Circle 22 on Inquiry card.

formed. Subtask 4 is performed as long as the condition within the hexagon (B>Y) is true. Of course, any subtask box may be further divided into its component subtasks.

Since any box can be broken into component subtasks, you can now see how this notation is used to design a program. The boxes in the leftmost column give the overall design of the program; boxes are then expanded to the right as each box (task) is divided into boxes representing the appropriate combination of subtasks. As a result, you can scan any one of several of the leftmost column of boxes for an overview of varying depths of the program design, or you can study the implementation of any major or minor subtask by concentrating on only the boxes and control structures growing to the right of the given subtask.

An Example

The following

example will il

( FINDMAXj

lustrate the process of developing a program using structured flowcharts. Using the example of table la, suppose you are given an array of N numbers, V(l), V(2),...V(N), and have to find the index value MAXINDEX such that the largest value in the V array is MAXV = V(MAXINDEX). The entire structured flowchart for this problem is given in figure 6.

Cover the right three-fourths of the flowchart so that only the subtasks numbered 1, 2, and 3 are visible. This is what the "first pass" of the flowcharting effort should look like. Subtask 1 is the initialization of the problem. Subtask 2 is the determination of MAXINDEX and MAXV. Subtask 3 is the printing of these two values. Since the task in subtask 3 is simple enough to be directly accomplished in the target language (for example, BASIC), it need not be subdivided.

Subtasks 1 and 2 are developed concurrently. Subtask 2 is basically a loop that examines V(l), V(2),...V(N) in turn, keeping the appropriate values for MAXV and MAXINDEX for the I elements encountered thus

INITIALIZATION

1.1

MAXV--S1Q'

1.2

MAXINDEX = 0

1.3

INDEX = 1

FIND LARGEST VALUE MAXV AND ITS INDEX MAXINDEX

2.1

WHILE INDEX <N

2.1.1

far. The values of MAXV, MAXINDEX, and INDEX must be set (as is done in subtasks 1.1, 1.2, and 1.3). Note that this loop could have been done more easily using a do-loop; other optimizations could also have been made, but this example is given for the purposes of illustration only.

The main work for each element is done as subtask 2.1.2: if the current V element being examined (ie:CURRV) is greater than the maximum V element so far, MAXV and MAXINDEX are set to the current array and index values, respectively. These subtasks, numbered 2.1.2.1 and 2.1.2.2, are performed only when the relationship given in the diamond of 2.1.2 is true.

Once the structured flowchart has reached the level of detail shown in figure 6, most of the design considerations have been conceived and perfected; it is then a simple task to translate the program into BASIC (see listing 2) or any other generalpurpose computer language. The benefits are more pronounced when used with a larger program. If a structured flowchart is subdivided to the right until each box represents a task that can be directly coded in the target language, you will catch most of the "oops, I forgot to..." insertions and changes that programmers generally think of after they have started coding the program.

Other Control Structures

Although the three constructs discussed so far are sufficient for writing any program, it is not always convenient to use only these constructs. Other control structures can be devised for the convenience of the programmer. For example, boxes 1.3,

CDRRV- V(INDEX)

2.1.2

PRINT MAXV, MAXINDEX

2.1.3

f END J

2.1.2.1

MAXV--CURRY

2.1.2.2

INDEX = INDEX + 1

MAXINDEX --INDEX

Figure 6: Structured flowchart for program F1NDMAX. Given an array V with N elements, the problem is to find the largest element, MAXV, and its index within the V array, MAXINDEX. The numbers above each box give the sequence and level of that box in relation to the entire problem. For example, box 1 can be broken into three subtask boxes: 1.1, 1.2, and 1,3.

32

March 1981 © BYTE Publications lnc

Circle 23 on Inquiry card.

Distributed CP/M processing. Up to 16 users each with independent CPU and memory.

*VJ!

'•I*

How to tell if it's a White Computer.

(Users 2 through 16 — multiuser expansion with high performance through distributed processing.)

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Look for independent 6 MHz Z80B-based User Modules with 64Rof RAM memory, each module with a port to the user term inal capable of handl ing baud rates of up to 38K under program selection. Look for high-speed block data transfers from user modules to the Global Processor for disk storage. That way, CP/M programs run independently for each user. Fast. And each users's station acts just like the fastest standalone system — no delays, no waiting for other users.

Look for a Z80-based Global Processor for disk and tape I/O that transfers data from disk to user modules at the data transfer rate of the peripheral device. And a controller that handles as many as 8

SMD disk drives for up to 528 megabytes of hard disk storage, plus up to four 8" floppies, plus optional streaming tape backup.

And look for a Z80-based General I/O Processor that supports up to eight printers — with 64K bytes of independent buffer memory.

That's part of how you tell if it's a White Computer. There's a lot more. Here's a number and address for more information.

CP/M is a registered trademark of Digital Reseach.

Z80, Z80A, Z80B are registered trademarks of Zilog Corporation.

White Computer Company A 1876 Industrial Way Redwood City, California 94063 A 415 364 7570

2.1, and 2.1.3 in figure 6 can be replaced by a control structure that is available in most programming languages—a do-loop that varies INDEX from 1 to N. An example of the notation I have devised for this is given in figure 7a; the body of the loop is performed according to the parameters given in the hexagon.

Another well-known control structure is the repeat...until loop, shown in figure 7b. The position of the body

of the loop, above and to the right of its associated hexagon, is meant to signify that the body of the loop is performed before the condition is tested. Although the meaning of this notation does not implicitly follow from its form, it was chosen for its simplicity and consistency with the notation already developed.

Other constructs come to mind: a case structure, an unconditional goto, and two controlled gotos—the restart

FOR I = 1 TO 10

BODY OF LOOP

BODY OF DO-LOOP

I UNTIL V(CONDITION)

(a I

lb)

Figure 7: Structured flowchart notation for a do-loop and a repeat. ..until loop. In the do-loop, figure 7a, the hexagon contains all pertinent information defining the loop, and in the form most comfortable to the user. In the repeat...until loop, figure 7b, the notation is interpreted as showing the body of the loop being executed before the condition is tested. In both cases, the box representing the body of the loop can be expanded to the right, into its component subtasks.

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(restart the innermost containing loop) and the exit (go to the first task after the innermost containing loop). Although I have used some of these constructs for quite some time, they are not presented here because I am not yet satisfied with the notations I have developed for them. In any case, structured flowcharts are meant to be a personal notation—you should add to and modify these constructs to fit your needs.

Conclusions

I have found structured flowcharts helpful in designing programs. The notation is obviously intended for weakly structured languages (like BASIC), as its utility decreases when the structure of the target language increases.

The notation is, at the moment, informal, and it should stay that way. It should be extended and modified in whatever way seems useful to you. In particular, you should use additional notation for special features of the target language (eg: global and local variables, use of a stack of intermediate computation) when applicable. If the structured flowchart is to be read by another person, however, you should define all the structures used in terms of their equivalent unstructured (conventional) flowcharts.

If the final structured flowchart is to be redrawn, you should do so with clarity in mind. Place only those boxes that help explain the overall design with the main flowchart; leave the implementation details to subordinate flowcharts.

I hope you will find this notation useful. I would appreciate your suggestions, criticism, and comments. ■

References

1. Page-Jones, Meillir. The Practical Guide to Structured Systems Design. New York: Yourdon Press, 1980.

2. Ross, D T, J B Goodenough, C A Irvine. "Software Engineering: Process, Principles, and Goals." Computer. Institute of Electrical and Electronics Engineers (IEEE), May 1975. Also Tutorial on Software Design Techniques, Third Edition, P Freeman and A I Wasserman, editors. Long Beach CA: IEEE Computer Society, 1980.

3. Williams, G. "Applied Structured Programming." Program Design, Blaise Liffick, editor. Peterborough NH: BYTE Books, 1978.

4. Classics in Software Engineering, E N Yourdon, editor. New York: Yourdon Press, 1979.

34

March 1981 © BYTE Publications Inc

Circle 24 on inquiry card.

TRS-80* Model I Computer Owners .

Double-density storage, It's really here!

Here at Percom. And your authorized Percom dealers.

And double-density storage is here in a big way. Because now you can choose from three different levels of mini-disk systems — all double-density rated.

And get the storage that precisely meets your application needs.

Not to mention the service and quality that's made Percom the industry leader.

1

ISK)

Although rated for double-density operation, all levels of Percom drives work equally well in singledensity applications.

You can operate these drives in ordinary singledensity format using TRSDOS*, Percom OS-80™ or any other single-density operating system.

Or, you can add a Percom DOUBLER™ to your Tandy Expansion Interface and store data and programs in either single- or double-density format.

Under double-density operation, you can store as much as 350 Kbytes of formatted data — depending on the drive model — on one side of a five-inch minidiskette. That's four times the capacity of standard 35-track Model I minidisks, almost 100 Kbytes more than the capacity of the eight-inch IBM 3740 format!

Available in 1-, 2- and 3-drive configurations in all three model lines, Percom burned-in, fullytested drives start at only $399.

TFD-40™ Drives

TFD-40 Drives store 180 Kbytes (double-density) or 102 Kbytes (single-density) of formatted data on one side of a 40-track minidiskette. Although economically priced, TFD-40 drives receive the same full Percom quality control measures as TFD-100 and TFD-200 drives.

TFD-100™ Drives

TFD-100 drives are "flippy" drives. You store twice the data per minidiskette by using both sides of the disk. TFD-100 drives store 180 Kbytes (doubledensity) or 102 Kbytes (single-density) per side. Under double-density operation, you can store a 70page document on one minidiskette.

TFD-200™ Drives

TFD-200 drives store 350 Kbytes (double-density) or 197 Kbytes (single-density) on one side of a minidiskette. By comparison, 3740-formatted eight-inch disks store only 256 Kbytes. Enormous on-line storage capacity in a 5" drive, plus proven Percom reliability. That's what you get in a TFD-200.

The DOUBLER™ — This proprietary adapter for the TRS-80* Model I computer packs approximately twice the data on a disk track.

Depending on the type of drive, you can store up to four times as much data — 350 Kbytes — on one side of a ^felt"* ™W"* minidiskette as you can store using a Tandy standard Model I computer drive.

Easy to install, the DOUBLER merely plugs into the disk controller chip socket of your Expansion Interface. No rewiring. No trace cutting.

And because the DOUBLER reads, writes and formats either single- or double-density disks, you can continue to run all of your single-density software, then switch to double-density operation at any convenient time.

Included with the PC card adapter is a TRSDOS*compatible double-density disk operating system, called DBLDOS™, plus a CONVERT utility that converts files and programs from single- to double-density or double- to single-density format.

Each DOUBLER also includes an on-card highperformance data separator circuit which ensures reliable disk read operation.

The DOUBLER works with standard 35-, 40-, 77- and 80-track drives rated for double-density operation.

Note. Opening the Expansion Interface to install the DOUBLER may void Tandy's limited 90-day warranty.

Free software patch with drive purchase. This software patch, called PATCH PAK,,M upgrades TRSDOS* for singledensity operation with improved 40- and 77-track drives.

Quality Percom products are available at authorized dealers. Call toll free 1-800-527-1592 for the address of your nearest dealer or to order directly from Percom. In Canada call 519-824-7041.

tm , Ir. r^ A i Prices and specifications subject to change without notice,

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PEACOM

trademark of Tandy Radio Shack Corporation which has no relationship to Percom Data Company

PERCOM DATA COMPANY, INC.

211 N KIRBY ■ GARLAND TX ■ 75042 1214)272-3431

Circle 25 on inquiry card.

Ciarcia's Circuit Cellar

Build the Disk-80

Memory Expansion and Floppy-Disk Control

Steve Ciarcia

POB 582

Glastonbury CT 06033

The term "memory expansion" no longer causes the same pained expression among computer owners as it did a few years ago. Back in the "Model T" days of personal computing, it was a major undertaking, often the largest expense of setting up a personal computer system. At that time, volatile memory integrated circuits contained only a fraction of the capacity of those available today, and mass storage often consisted of slow audio cassettes.

Back in 1975, if you were adding 32 K bytes of memory to your computer you would probably have used 256 type-2102A 1 K by 1-bit static memory chips. These cost between $2 and $5 each, and you probably would have needed a power supply larger and heavier than the computer. Believe it or not, the 2102A was a major improvement over the previous type-1101 memories (256 by 1-bit static devices). It would have taken 1024 (1 K) of the type-1101 components to make 32 K bytes.

Since that time, memory technology has progressed by leaps and bounds, and the cost per bit has dropped considerably. Many computer manufacturers now use dynamic

rather than static memory. The result is much higher density, lower system cost, and easier after-market memory expansion on most computers.

The 64 K-byte personal computer system is more common than you would imagine. Adding another 16 or 32 K bytes of memory these days simply means plugging a few (8 or 16) integrated circuits into a memoryexpansion unit or motherboard. Usually the standard power supply suffices.

Even with these advantages, using

Photo 1: The Disk-80 mounted in its enclosure and attached to the TRS-80 Model 1 computer. The Disk-80 is about half the size of the Radio Shack TRS-80 Expansion Interface.

dynamic memory is not quite as simple as it sounds. There are considerable differences between static and dynamic memory. Most people know relatively little about designing a dynamic-memory system, and even professional designers are intimidated by having to deal with multiplexing addresses, selecting bus drivers, sequencing activation of power supplies, and decoupling and noise. I don't expect that reading this article will make you into an authority on dynamic memory, but perhaps you will at least have a better understanding of it.

Mass-storage technology has also progressed during this same period. Displacing the audio cassette as the exclusive medium, the floppy disk and Winchester-technology hard disk have become the de facto storage standards.

For some time I have wanted to present articles on dynamic-memory and disk-controller integrated circuits. I have delayed chiefly because I generally prefer to present my articles as usable applications.

The three largest-selling personal computers, the Radio Shack TRS-80, the Apple II, and the Commodore

36

March 1981 © BYTE Publications Inc

Photo 2: The Disk-80 printed-circuit board (circuit of figure 2). The red cable connects to the expansion connector on the TRS-80 keyboard/processor module. The 34-pin edge connector above the red cable is a 5-inch floppy-disk drive interface connector. The sixteen integrated circuits lined against the left side of the board are 32 K bytes' worth of type-4116 16 K-bit dynamic memory devices.

PET, use 16 K-bit dynamic-memory chips. Only the TRS-80 Model I requires the user to add extra memory via an external module, the TRS-80 Expansion Interface. (The TRS-80 Model 111 does not.)

This month's hardware project, the Disk-80, is an expansion interface for use with the TRS-80 Model I that expands the user memory and provides for the attachment and control of floppy-disk drives. Dynamic memory and a specialized floppy-disk-drive controller are used. Although this project was designed for use with the TRS-80 Model I, the elements of the systems and the principles involved are applicable to any personal computer.

What's Inside the Disk-80?

The Disk-80, shown in photo 1, is completely hardware- and softwarecompatible with the TRS-80 Model I and includes hardware enhancements for increased reliability. Readers familiar with the TRS-80 Expansion Interface will note that the Disk-80 is

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

considerably smaller.

The keyboard/processor module of the TRS-80 Model I system is a singleboard computer with memorymapped video display and keyboard. The only provision for I/O (input/output) in the basic configuration is an I/O port for an audiocassette recorder and a single-bit relay line for control of the recorder motor. Any user-memory expansion beyond 16 K bytes and any printer or disk I/O must be handled externally. The unit sold by Tandy/Radio Shack to perform these functions is called the TRS-80 Expansion Interface.

Figure 1 is a block diagram of the Disk-80. It attaches to the keyboard/processor unit through the 40-pin TRS-BUS connector and provides the following functions: 32 K-byte user-memory expansion, Centronics-compatible parallel printer port (full 8 bits), real-time clock, four-drive 5-inch floppy-disk controller, external data separator (used in reading floppy disks), buffered TRS-BUS connection to other peripheral devices, and power supply.

The three major functional sections are as follows:

• Memory-expansion section, which accommodates up to 32 K bytes of dynamic memory;

• Four-drive 5-inch floppy-disk controller; and

• Parallel printer port.

The activities of these sections are coordinated through a common address decoder.

The Disk-80 system is divided into two circuit boards. The main board, shown in photo 2 and outlined schematically in figures 2a, 2b, and 2c, contains everything except the power supply and the printer port. The other board, referred to as the power-supply/printer-interface board, is shown in photo 3 on page 45.

Disk-80 Addressing

The disk controller, printer, and real-time clock are addressed as memory-mapped parallel I/O ports through IC28, a 74LS155 decoder. Eight strobe signals are produced to decode memory addresses within the range of hexadecimal 37E0 to 37EC (only six of these are used in the Disk-80) to coordinate these peripherals. Their functions are shown

March 1981 © BYTE Publications Inc

37

POWER-SUPPLY/PRINTER-INTERFACE BOARD

POWER SUPPLY

(TO ALL SECTIONS)

B-BIT LATCH

AND

B-BIT INPUT BUFFER

~N

36-PIN PRINTER-PORT EDGE CONNECTOR

DISK-BO BOARD

ADDRESS

BUS

BUFFERS

ADDRESS DECODER (TO ALL SECTIONS)

DATA BUS BUFFERS

FLOPPY- DISK CONTROLLER CHIP

REAL-TIME CLOCK

32 K-BYTE EXPANSION MEMORY

CLOCK GENERATOR

HARDWARE

DATA

SEPARATOR

LINE DRIVERS

LINE RECEIVERS

J"

•\

34-PIN

FLOPPY-DISK DRIVE EDGE CONNECTOR

Figure 1: Block diagram of the Disk-80 expansion interface for the Radio Shack TRS-80 Model I.

Elements of the

systems presented and

the principles involved

are applicable to any

personal computer.

in table 1 on page 44.

IC26, an eight-input NAND gate, and IC27, a 74LS139 decoder, function as memory-bank decoders. They produce two strobe signals. One, designated 32 K (or informally, 32 K enable), is the active-low enable strobe for expansion memory between hexadecimal addresses 8000 and BFFF. The second strobe, 48 K (or 48 K enable), controls the bank of memory between C000 and FFFF.

Operation of Dynamic Memory

When designing memory systems,

it is necessary to understand both the components and the computer system. In the past, the most popular dynamic memory components were MK4096- and MK4027-type 4 K by 1-bit devices. Today the standard memory component in personal computers is the MK4116. (More recently, maximum density has increased to 64 K bits per chip. Unfortunately, these parts are expensive, about $70 each, and are not yet generally used in personal computers.)

The 4116 is a 16 K-bit dynamic memory device. The 14 address bits required to specify one of the 16,384 cell locations that each store a single bit of data are multiplexed into seven shared pins. The timing of the signals presented to these pins is shown in figure 3 on page 45.

During execution of a Z80 memory-read or memory-write instruction, a 16-bit address is present on the processor's address bus. If the memory address is between hexa

decimal 8000 and FFFF, the processor will try to find the addressed memory devices in the Disk-80's memoryexpansion section. Decoding address lines A14 and A15 determines whether the location is in the 32 K or the 48 K memory range and enables the appropriate bank. The remaining 14 bits are multiplexed directly into the eight 4116s (one 4116 is used for each bit of the addressed byte location).

IC20 and IC21, 74LS157 quad 2-to1-line multiplexers, apply the first 7 row-address bits to each 4116 when the MUX (multiplex) and RAS (row-address strobe) signals are low. This latches the row address into the 4116. Next, the MUX signal goes high, applying the 7 column-address bits to the 4116, and CAS (columnaddress strobe) goes low. At the conclusion of this sequence, data is either written into or read from the 4116

Text continued on page 44

38

March 1981 © BYTE Publications Inc

RIBBON-CABLE 40-PIN

CONNECTOR

TO J2 +5V

HZ>32K

Figure 2a: Schematic diagram of the address-decoding and buffering section of the Disk-80. Figure notes are found in the text box on page 44.

March 1981 © BYTE Publications Inc

39

AO'OAl'OA2'C>A3'C^

A7'0AS'O

A9'C~ AIO'O

11

14

1Y

2Y

3Y

4Y IC21 * IB 74LS157

2B 3B 4B G

Rl 47fl

(TYPICAL FOR 4) 0

12

-Wr —Wv_VW

+5V

IC19

MRAS

-^AO IC1 7 4116

-*■ Al

"5 A2

12

10

13

15

* * [l |8 |9 |l6

A3

A4 A5 A6 WR RAS CAS OUT

IN

U f,VK 47fl

—Wi—

14

* *

12

11

10,

13 3

15

li Is [g lis

IC9 4116

A0 Al A2 A3 A4 A5 A6 WR RAS ■CAS OUT

IN

14

Figure 2b: The memory-expansion section of the Disk-80 module. See notes on page 44.

40 March 19S1 © BYTE Publications Ihc

* *

I 8 9 IE

* *

Ills Is

+12V*

5 7 6 12

11 10 13 3 4 15

IC2 4116

OUT IN

16

12

11

10

13

* *

1 8 9 16

IC3 4116

OUT IN

* *

Ji|s |g lis

_5 _7 _6 J2

_n

10

J3 _3 _4 15

IC10 4116

OUT IN

11

10

* * 1 8 9 16

IC4 4116

OUT IN

* *

Jilejg I is

ICll 4116

14

14

|i e I9 lie

10

13

IC5 4116

OUT IN

14

* * |l |e I9 |l6

IC12 4116

OUT IN

14

10

13

15

1 8 9 16

IC6 4116

OUT IN

* *

1 8 9 16

IC13 4116

OUT IN

14

10

13

IC7 4116

OUT IN

* * 1 8 9 16

IC14 4116

OUT IN

14

-5V

12

15

C67, ,100/iF

-M

C70 10/iF

ic8

4116

OUT IN

1 8 9 16

IC15 4116

OUT IN

rh

5V* A

■C68 'lOO^F

rh

16

* * 1 8 9 16

IC16 4116

14

March 1981 © BYTE Publications Inc 41

RIBBON-CABLE PC CONNECTOR

40 PINS J2

"1

D7[2(5>

D6[U>

D5[5£>

D4|l8>

D3|26>

D2|H>

Dl|2^>

D0|1^—

INT<2U

I

C9 68pF

SYSRES[2>

O I I

6~

DO Dl D2 D3 D4 D5 D6 D7

0 0 ft 0 0 0 0

£

I~TC 41 1 I 74LS367 1

1s*1 r

► 5V

IR27 J4.7K

IC39 *

.74LS240

IS*

16

^J^

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^

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^

$>

IB

znfczz

_l

3-«^

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^

^

I »

4<p

J^ja.

IC40 74LS24

<L*_J

I 10 'llll

-O37E0RD

I -M | 12 ^13 I

CRY2Stt Ua» J 'DHt—I

—L-(

IC44 * QD

74LS90 R0(1)

R0(2)

A R9I1)

BDIN R9I2)

QA

M2

10

El 204

E2 104

IC45 cki

CD4 518 CK1

RST1

RST2 CK2

10

El 204

E2 104

IC46 CK1

CD4 518

RST1

RST2 CK2

14

m

a Hze T 4.7K

I vw e

tR28 J4.7K

CLOCK 0

IC4 7a *

74LS74 D 0

11

jt:

Jk.

CLOCK

IC48b 74LS74

37E0RD[^>

10

X

IC48o 74LS74

CLOCK

11

39

JT

. ALL OTHER

UNDESIGNATED \PINS CONNECTED /DIRECTLY TO J3 I EXCEPT AS NOTED

N/C = NO CONNECTION

37ECRDl3>37ECWRH

DISK-CONTROLLER, CLOCK-GENERATOR, AND COMPUTER-INTERFACE SECTION

Al'O" AO'O

DAL7

DAL 5

DAL 3

DAL2

NTRQ

IC42 * INS1771D-1

DISK CONTROLLER

MR RE WE Al AO

Figure 2c: Schematic diagram of the disk-controller, clock-generator, keyboard/processor-module-interface, external-data-separator, and disk-drive-interface sections of the Disk-80 expansion module. See figure notes on page 44.

42 March 1981 © BYTE Publications Inc

►5V

C4 100MF

HLT RDY

STEP DIREC

WG WD

EXT CLOCK

DATA XTDS

IC42 DISK CONTROLLER

WPRT

Tp

TROO 3PM

TEST

WF

DINT

14

37E0WRO

f5V t

R24

4.7K

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r

^

. Rll I91K

Jl

15

CEXT

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IB

IC330 74LS123

13

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D30^

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13

37E0WR^>

IC31 74LS20

32

<Li

15

I 1

fr*

IC29 7416

34-PIN

DISK DRIVE BUS

CONNECTOR

CLR 4D

3D

2D

ID

CLOCK

IC32 * 74LS175

40 30 2Q

10 40 3Q 2Q 1Q

15

$£> MOTOR ON

14

L

■[32> DS3 ■|14> DS2 M> DS1 ■(10> DSO

30

IC30 !

7416 !

"N>

26

IC36 4 ^d3_

IC36 74LS04

^<F

IC35 74LS00

<Dn

C 7 ri ?

\°°'F 6 2K

10 12

IC37a 74LS74

CLOCK C

IC380 * 74LS74

CLOCK Q

C

11

10

IC38b 74LS74

CLOCK

13

IC36 74LS04

Wfe

18

22

-i-M^-—^

lR22 >4.7K

f5V

DATA-SEPARATOR AND DISK-INTERFACE SECTION

IC50 74LS14

March 1981 © BYTE Publications Inc 43

Text continued from page 38:

depending upon the polarity of the Write Enable input. In turn, the Read Enable line controls the direction of data flow through the memory data buffers, IC17 and IC18, 74LS244 non-inverting octal buffers.

The MUX, CAS, and RAS signals are generated within the TRS-80 keyboard /processor module in a 3-bit shift register. Figure 4 on page 46 illustrates, in simplified logic, the derivation of these signals.

At the beginning of each read or write cycle, the Z80 microprocessor's MREQ (memory request) line is pulled low. The MREQ signal is also used by the TRS-80 as the RAS signal. The RD and WR (negativelogic read-enable and write-enable) lines are logically ORed to feed the CLR (clear) inputs and the D input of FF1, the first flip-flop in the 3-bit shift register. When either RD or WR goes low, a logic 1 is loaded into FFl at the occurrence of the rising edge of the 10.6445 MHz master clock pulse. On the next clock pulse, the logic 1 is shifted into FF2, the second flip-flop, of which the Q output controls the MUX signal. The next clock pulse shifts the logic 1 into flip-flop FF3. The inverted Q output of FF3 is the CAS signal to memory. When theRD or WR line goes high again, the three flip-flops are cleared and the

Notes

1. On IC1 thru IC16 (the 4116 components) the +5 V lead on each IC should have one decoupling capacitor. One decoupling capacitor should be on every other chip for the +12 V and —5 V leads, for a total of thirtytwo decoupling capacitors. Careful placement of decoupling capacitors is absolutely critical to proper operation.

2. All other places where decoupling capacitors are required are denoted by an asterisk (*) on the diagram.

3. All capacitors are 12 V ceramic disk type unless otherwise noted.

4. All resistors are 1/4 W 5% tolerance carbon-film type unless otherwise noted.

address multiplexers are reset.

It is easy to see that multiplexing the addreses is fairly simple, especially when the signals needed are available on the 40-pin TRS-BUS connector.

Interestingly enough, Radio Shack did not use these signals in late

production TRS-80 Expansion Interfaces. Because some of the signal pulses are very short in duration (about 200 ns) and susceptible to noise, the early-production Expansion Interfaces had to have a buffered cable to eliminate memory errors. Eventually, this arrangement was

Write Strobes

37E0 — disk-drive select (1 ot 4)

37E4 — not used

37E8 — printer data out

37EC — set disk-controller registers

Read Strobes 37E0 — read real-time clock/reset interrupt 37E4 — not used 37E8 — read printer status 37EC — read disk-controller registers

Table 1: Hexadecimal memory-mapped addresses of registers used by the Disk-80 to coordinate the disk-drive controller, the printer interface, and the real-time clock.

IC N

umber

Type

+ 5V

GND +12V -5V

1 thru 16

4116 (200 ns)

9

16

8 1

17

74LS244

20

10

18

74LS244

20

10

19

74LS32

14

7

20

74LS157

16

8

21

74LS157

16

8

22

74LS00 •

14

7

23

74LS14

14

7

24

74LS244

20

10

25

74LS244

20

10

26

74LS30

14

7

27

74LS139

16

8

28

74LS155

16

8

29

7416

14

7

30

7416

14

7

31

74LS20

14

7

32

74LS175

16

8

33

74LS123

16

8

34

74LS123

16

8

35

74LS00

14

7

36

74LS04

14

7

37

74LS74

14

7

38

74LS74

14

7

39

74LS240

20

10

40

74LS240

20

10

41

74LS367

16

8

42

INS1771D-1

21

20

40 1

43

CD4049

1

8

44

74LS90

5

10

45

CD4518

16

8

46

CD4518

16

8

47

74LS74

14

7

48

74LS74

14

7

49

74LS00

14

7

50

74LS14

14

7

51

Table 2: List of integrated circuits and power-win

ng requirements for the Disk-80,

excluding those integrated circuits found on the

optional

power-supply/ print er

interface circuit board.

The entity marked IC51 on

the schematic diagram is really a

connector for

the 14-conductor ribbon

cable running between the power-supply/

printer-interface board and the disk-cor

troller board.

44

March 1981 © BYTE Publications Inc

replaced with a circuit in the Expansion Interface that derives the MUX and CAS signals by sending RAS through a delay line. Of the three original signals, only the RAS signal, which has the longest pulse duration, is used.

If cable lengths are kept to a minimum and proper signal termination is employed, there is no good reason why any signal available from the keyboard/processor module should not be used. The Disk-80 uses a combination of active termination and Schmitt-trigger inputs to guarantee reception of all available signals.

Memory Refreshing

So far you have heard only the good things about dynamic memory. One of the less desirable characteristics is called memory refreshing. Unlike static memory, which stores data in active bistable circuits composed of three transistors, the dynamic 4116 stores its Is and Os in single-transistor cells that simulate capacitors. As from a capacitor, the electrical charge that represents a bit slowly drains off unless it is "refreshed." Refreshing is accomplished by addressing ail memory cells (or a required minimum of them) on a regular basis.

The 4116 is a RAS-only-refresh device. Instead of addressing all 16,384 bit-cell locations, only the 128

rows are cycled. This type of

refreshing uses only the RAS signal and is achieved in less time than methods that use both row and column addressing. Because the MUX and CAS pulses are not used, the memory is not enabled, and the refreshing does not interfere with other system operations. However, all 128 rows must be addressed at least every 2 ms to avoid loss of data.

Refresh circuits are generally binary counters that generate sequential addresses which are applied to the memory chips. The Z80 processor includes a built-in 8-bit RAS-only refresh register. During the decoding and execution of an instruction op code, the 7 bits of the refresh register contents are placed on the low-order lines of the address bus, and the MREQ line is strobed. In effect, the Z80 accomplishes "hidden refresh" as it executes its normal program. For more information on this capability, I refer you to the Zilog

Z80-CPU Technical Manual.

Sequencing the Power Supply and Decoupling

Unfortunately, in addition to refreshing dynamic memory, a designer has to be concerned about sequencing the turning on of the

ov

+ 5V

OV + 5V

OV + 5V

Dqut

Figure 3: RAS, CAS, and MUX timing diagram for 4116-type 16-pin dynamicmemory integrated circuit. A 14-bit address (16,384 by 1) is multiplexed into seven address pins. When MUX and RAS are low, the row-address bits are read into the 4116. Later, when MUX is high and CAS goes low, the column bits are read into the 4116, activating the data output for that memory cell.

power supplies. While some brands of type-4116 memory devices are more tolerant than others, the following rule must be applied: the —5 V supply (VBb) must be applied to the 4116 before the +12 V supply (VDD), and the —5 V supply must remain on until the +12 V supply has been removed. The +5 V (VCc) supply is less critical, but it is best to turn it on and off synchronously with the +12 V supply. Many dynamicmemory components have been destroyed by designers not adhering to these rules.

Supplying Power

Power-supply sequencing is important because many power supplies overshoot their rated voltages when they are turned on. If VBB ( — 5 V) is not turned on and VDD (+12 V) overshoots to more than +15 V, the chip will blow. Applying VBB first provides an extra margin to prevent device destruction. Also, VBB must never go positive with respect to any other input.

The Disk-80 power supply, shown in photo 3 with the optional printer interface, meets these requirements. It is designed such that the time constants of the various sections produce a phased start-up and shutdown. This sequential operation is primarily achieved by use of filter components

Photo 3: The Disk-80 power supply with the parallel printer interface. The power supply provides 1 A at +5 V, 400 mA at +12 V, and 50 mA at — 5 V, and is designed for use with dynamic memories such as the 4116 that require sequenced application of power.

March 1981 © BYTE Publications Inc 45

TRS-80 KEYBOARD/PROCESSOR UNIT

0

AO

A}

A2

A3

A7

A8

A9

A10

Z80 PROCESSOR

A4

A5

A6

All A12 A13

EQUIVALENT OF "OR" GATE

10.6445[3>—<

MHz

CLOCK

3-BIT

SHIFT REGISTER

D 0

FF1 74LS74

CLOCK

CLR

D 0

FF2 74LS74

CLOCK

CLR

FF3 74LS74

CLOCK Q CLR

EXPANSION INTERFACE UNIT

1Y

2Y

74LS157

1A

2A

3A

4A

IB

2B

3B 4Y

4B S

3Y

ADDRESS MULTIPLEXER

1A 2A 3A

IB 2B 3B

1Y

74LS157 2Y

3Y

MK4116 A0/A7

A1/A8

A2/A9

A3/A10

A4/A11

A5/A12 D0UT

A6/A13

WR

RAS CAS

J

1

-5V

(16K BY 3 BIT)

.DATA OUT

Figure 4: Simplified schematic diagram of the internal circuitry of the TRS-80 Model I showing the derivation of the memory-refresh logic.

that are matched to the transformer impedance. Also, because I have designed it around a transformer with specific secondary voltages, the Disk-80 power supply is very efficient and produces relatively little heat. It is designed as a separate circuit board, allowing it to be used with any project requiring power for dynamic memory. It easily powers the full fifty-four-chip Disk-80, including 32 K bytes of memory.

A Centronics-compatible parallel printer port can be optionally built on the power-supply board. A schematic diagram of this port was printed in my previous article, "I/O Expansion for the TRS-80, Part 2: Serial Ports," BYTE, June 1980, page 42.

Finally, techniques of properly distributing power and decoupling transient noise voltages must be ad

dressed. Correct layout of the components in the Disk-80 is critical. The 4116s can generate high-current transients when in operation. Resulting voltage spikes can cause data loss unless the voltage transients are minimized by properly placed decoupling capacitors (a capacitor, usually a ceramic disk type with a value of 0.01 *iF to 0.1 /i¥ attached between power and ground).

Some suggestions that are of particular concern in the memory area of the circuit board:

• Decouple the VBB and VDD supply lines on every other chip.

• Distribute larger capacitors around the board to reduce supply-voltage droop.

• Decouple Vcc every few chips. •Keep signal lines short.

Real-Time Clock

To be compatible with TRS-80 hardware, the Disk-80 contains a real-time clock. It provides an interrupt to the Z80 at a rate of 40 times a second (every 25 ms). When the NMI (nonmaskable interrupt) is enabled, the clock-produced interrupts cause the Z80 to transfer control to a specific ROM (read-only memory) address (the interrupt vector). Unless there is a user-supplied routine to be executed, the Z80 simply returns from the interrupt sequence and continues where it left off. Various disk operating systems for the TRS-80 use an interrupt-servicing routine called in this manner to increment a time-ofday clock or event timer.

Five-Inch Floppy-Disk Controller

The Disk-80 uses an LSI (large

46 March 1981 © BYTE Publications Inc

TO DISKCONTROLLER CHIP SEPARATED

XLOCK

74LS04

EXTERNAL DATA SEPARATOR

74LS00

I-5V

EXTERNAL^—I CLOCK ^—r

-<

DATA

<^-<3

SEPARATED DATA

+ 5V

\

^y^y1

FALSE CLOCK WINDOW GENERATOR

^h

5.4/iS 74LS123

■>■

-)h

H5V

400ns

74LS123

-<&

FLOPPY-DISK DRIVE

-<CDread DATA

74LS14

~2

► 5V J

+ 5V

L

DATA-WINDOW GENERATOR

-vyt

74LS74

74LS00

->T>,

CLOCK 0 C

CLOCK Q C

74LS74

CLOCK 0 C

3-BIT COUNTER

Figure 5: Simplified schematic diagram of a 5-inch floppy-disk external data separator. The internal data separator of the FD1771 is not recommended for use in such applications. This circuit can be added to any existing TRS-80 Expansion Interface (which does not have an external data separator) to improve performance.

scale integration) floppy-diskcontroller integrated circuit. This one component performs the following functions: encoding, decoding, pattern recognition, serial-to-parallel and parallel-to-serial conversion, CRC- (cyclic redundancy check) character generation, and control of the disk-drive mechanism.

Floppy-disk controllers are available from a number of manufacturers in both single- and doubledensity versions. Since practically all TRS-80 Model I disk software is stored in single density, the Disk-80 uses a Western Digital FD1771-B01 single-density disk-controller integrated circuit. This component is second-sourced by National Semiconductor as the INS1771D-1.

The standard single-density 5-inch floppy-disk drive stores 110 K unformatted bytes per disk distributed on thirty-five tracks (some drives can use

forty or more tracks). Using a softsectored format like that used in the IBM 3740 Data-Entry System, each track is divided into 16 sectors storing 128 bytes each. The total amount of data that can be stored on a disk is a function of the disk operating system and the number of tracks per disk supported by the drive itself.

The 5-inch floppy disk is rotated by a DC motor at a speed of 300 rpm. An 8-inch floppy-disk drive contains an AC synchronous motor, which spins the disk at 360 rpm. The bit density of the data is the same, but, due to the differences in rotational speed and disk diameter, the 5-inch drive transfers data at 125 kbps (thousand bits per second) as compared to the 8-inch drive's rate of 250 kbps. The 5-inch drive's lower data rate makes programmed I/O a practical transfer method. Programmed data transfer through

specific registers requires less complex hardware than DMA (direct memory access) transfer.

Drive selection is handled by IC32, a 74LS175 4-bit register, and IC33a, a 74LS123 one-shot (monostable multivibrator). Only one drive is selected at a time, and the drive motors are turned off between disk accesses. To address a particular drive, a one-of-four drive code is loaded into IC32 through the memory-mapped register at hexadecimal address 37E0. This action starts a 5-second "motor-on" timer, which is activated whenever a drive is selected. It also activates the Head Load Time (HLT) control line on the FD1771. The software takes into account the 1 second required for the motor to come up to speed and the 80 ms required for head loading. Unless another access is made to this same drive, the motor will shut off

March 1981 © BYTE Publications Inc 47

The following items are available postpaid in the US from:

The MicroMint Inc 917 Midway Woodmere NY 11598 (516) 374-6793

Item

Ordering Description

Price

Disk-80 blank circuit board (containing no components)

Disk-80 PCB

$48

Power-supply/printerinterface blank board

PWR/P1 PCB

$16

Power-supply only blank board

PWR PCB

$12

INS1771D-1 disk controller chip with manual

INS1771D-1

$24

16 K bytes (8 chips) of memory: 4116s, 200 ns

16 K MEM

$40

prime units

Power supply complete kit: PC board and parts (add $15 for printer port and parts)

PWR Kit

$38

Disk-80 complete kit: case, power supply, printer port, cable and 16 K memory

Disk-80 Kit

$275

Disk-80 expansion interface: completely assembled and tested with 16 K bytes of memory and printer port

Disk-80 Assembled

$379.95

All printed-circuit boards are solder-masked and silkscreened and come with assembly instructions. Various other components and kits are also available. Call or write for a complete price list.

New York residents please add 7% sales tax.

Photo 4: External-data-separator section of the Disk-80 board. An external data separator is recommended when using the FD1771 disk controller with the 5-inch floppy disks. This circuit (shown in figure 5) can also be added to the Radio Shack TRS-80 Expansion Interface to improve performance. After setting the adjustment potentiometers, use nail polish as shown to lock their positions.

after 5 seconds.

The Z80 bus structure makes it relatively easy to use a floppy-disk system. All data, commands, and control for the FD1771 are handled through conventional memoryreference instructions. Eight memorymapped ports (four in and four out) handle all the communication between the Z80 and the FD1771. The range of addresses is hexadecimal 37EC to 37EF.

The Z80 controls the FD1771 through eleven commands, which are divided into four groups:

Type I —Commands that move the read/write head: Restore, Seek, Step, Step-in, Step-out.

Type II —Commands that read and write data: Read sector, Write sector.

Type III—Commands that perform status checking and formatting: Read address, Read track, Write track.

Type IV—Force-interrupt command.

An address map of Type I, II, and III FD1771 register-access functions is shown in table 3 on page 50. The commands and data are communicated to the FD1771 by setting the appropriate logic levels on address lines A0 and Al (pins 5 and 6 on the _FD1771) and strobing either the RE (read-enable) or WE (writeenable) inputs (pins 4 and 2).

Many disk-control commands require a parameter such as a track or sector address. This data must first be loaded into the appropriate register in the FD1771. To send a track address, for example, the 8-bit track address is loaded into the Z80's accumulator, and a store-accumulator [LD (HL), A] instruction to the track-register port at address 37ED is executed.

Of the FDl771's sixteen control

48

March 1981 © BYTE Publications Inc

Circle 26 on inquiry card.

baZic is written entirely in Z80® code—baZic runs as much as 30% faster than North Star8 BASIC. The greater execution speed is significantly advantageous forhea\y number crunching, multiuser and multitasking operations.

baZic has all the features of North Star BASIC— and then some. baZic, with minor exceptions, is 100% compatible with existing North Star BASIC programs. Our new baZic runs under all Micro Mike's timesharing and hard disk operating so tware, including JOEDOS/JOESHARE/ HDSHARE and 5SHARE.

CHECK THESE FEATURES AT YOUR COMPUTER DEALER:

■ Takes full advantage of the Z80 instruction set

■ Can be used on any Z80-based microcomputer operating under North StarTJQS or CP/M® (CP/M versions available early '81)

■ Supports North Star floating point board for even faster execution of compute intensive programs

■ Makes Multiuser systems with floppy disks more practical

■ Improves performance of Multiuser Hard Disk systems

■ baZic adds functions to assist in screen formatting, as well as features to simplify programming, e.g. APPEND command/ statement, ON GOSUB, cursor-addressable PRINT, etc.

■ baZic, as shipped, includes 8,10,12 and 14 digit precisions, including both software and hardware floating point versions

■ baZic is now included with Micro Mike's operating system software and applications programs

Dealers and OEM's: Special Discounts Available

For complete information, contact your North Star dealer or send $1 to Micro Mike's for complete technical presentation.

gNorth Star Computers. Inc.

"ZiloH, Inc.

^Digital Research, Inc.

JMAfee a

Micro Mike's Inc.

905 S. Buchanan, Amarillo, Texas 79101

806-372-3633

[ardfact:

>150 package makes your Horizon execute programs up to 30% faster!

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lines, seven interface directly to the disk drive through drivers and receivers (type-7416 and 74LS14 components). The Write Data line transmits the digitized serial composite data to be written on the floppy disk. The Write Gate line enables the actual writing process. The Index input transmits the pulse from the index-hole photodetector that indicates the beginning of a track, and the Write Protect line tells the controller when a writeprotected disk has been inserted into the drive. The Track 00 line is activated when the read/write head is positioned over track 00 (the outermost track) of the disk's surface. The Direction Select line defines the direction in which the head will move when the Step line is pulsed. Each pulse moves the head one track.

An External Data Separator Is the Best Insurance

As previously mentioned, the 5-inch floppy-disk drive transfers data at 125 kbps, while an 8-inch drive transfers at 250 kbps. The difference in data rates affects the data separator's timing values as well as the clock rate used by the controller chip. The 5-inch drive requires a 1 MHz clock, while a standard 8-inch drive uses a 2 MHz clock.

Data received from the drive's electronic circuitry is a multiplexed combination of data and clock pulses. The FDl771's internal data separator can separate the data and clock bits, but use of the FDl771's internal data separator is not recommended where high reliability is required. An external data separator must be added to maintain a soft-error rate better than 1 in 10s.

The internal separator operates from the 1 MHz system clock, which is not synchronous with the clock pulses of the disk data. Due to mechanical variations and other factors, sometimes a bit of data can arrive at the FD1771 at a point in time "outside the data window," that is, when the controller is not expecting it.

[Editor's Note: For a more detailed explanation of the importance of the data window, see "Interface a FloppyDisk Drive to an 8080A-Based Computer" by John Hoeppner in the May 1980 issue of BYTE, page 72....RSS] The nonsynchronous data window's 1 ins (microsecond) resolution can

Hexadecimal Memory-Mapped

37EC 37ED 37EF 37EF

A1

0 0 1 1

A0

0 1 0

1

37EC Read Enable

Status Register Track Register Sector Register Data Register

37EC

Write Enable

Command Register Track Register Sector Register Data Register

Table 3: Memory-mapped addresses used by the Disk-80 to communicate with the FD1771 or INS1771 floppy-disk-controller integrated circuit. The FD1771 interacts with the Z80 processor by memory-reference instructions, not by DMA. The FD1771 can execute eleven high-level function commands.

MISSING CLOCK PULSES

SERIAL DATA

DATA WINDOW (6Ms ONE-SHOT)

FALSE CLOCK PULSE GENERATOR <5.4,is ONE-SHOT)

SEPARATED DATA

i n p

n^rnL^nL^

L

n

U L

1_

i

1

"1"

Figure 6: Timing diagram illustrating the operation of the external data separator shown in figure 5 on page 47. Clock pulses are denoted by the letter C, data pulses by the letter D.

move with respect to a data bit's arrival by enough that the data bit can actually fall outside the data window. This would be interpreted as an error.

To help eliminate what has been a major problem for TRS-80 Model I disk users, the Disk-80 includes an external data separator. Neither the Radio Shack TRS-80 Expansion Interface nor the LNW Research System Expansion Board has an external data separator. Figures 5 and 6 illustrate the circuitry and function of the Disk-80's external data separator.

The external data separator places a 400 ns (nanosecond) one-shot on the Read Data line from the drive. This arrangement reduces the Read Data input pulse width from 1.2 (is to 400 ns. When configured for external clock and data separation, the FD1771 requires pulse widths between 300 and 700 ns. The narrower the pulse width, the better the data separator's resolution.

To produce the separator's data window, a 6 fts one-shot is triggered by the leading edge of the clock pulse. Since the time between clock pulses is

8 (is, a data bit is expected within 4 fis after the clock pulse's leading edge. The extra 2 (is allow for shifts in the phase of the data or clock bits. This is all that is required to satisfy any potential timing problems. However, since we also have to be IBM 3740 compatible, more is required.

The IBM 3740 format creates a unique addressing mark by dropping three clock pulses during the addressmark clock pattern. To produce data windows during missing clock-pulse intervals, a false clock pulse is generated with a 5.4 (is one-shot. If the 5.4 (is one-shot times out past the expected instant of the next clock pulse, its own pulse's trailing edge triggers the other (6 /is) one-shot, generating a data window.

A 3-bit counter distinguishes between missing clock pulses and address marks. If the data separator is already in phase, it is constantly reset by the separated clock output. When the separator encounters the address mark, the counter is incremented by a pulse on the separated data line. On the occurrence of the fourth missing

50

March 1981 © BYTE Publications Inc

The

Brains of Men

and Machines

by Ernest W. Kent

When the "Brains of Men and Machines" series of articles originally appeared in BYTE magazine, the response was immediate and enthusiastic. Now Ernest W. Kent has expanded his ideas about the brain into a full-length book.

As researchers begin to unravel the mysteries of the brain's chemical, electrical, and synaptic circuitry, their findings are becoming immediately applicable to advances in robotic behavior and computer design. The Brains of Men and Machines "dissects" the brain to provide new insights into computer design and artificial intelligence.

It is one of the rare books that transcends disciplinary boundaries. In it the ever increasing relationship between man and machine is freshly examined — a relationship, Professor Kent concludes, that is today being reexamined in the light of man's own neurological self-image.

T T , no . Call TOLL FREE: 800-258-5420

Hardcover 304 pages or Mail To:

ktitiIj! 70 Main SL

BLIIirya Peterborough, NH 03458

ISBN #0-07.034123-0

Price 115.95

Please remit in U.S. funds or draw on a U.S. Bank

Please send □

. copies of

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m

clock pulse, the data window is reset. The separator becomes in-phase again on the next true clock pulse.

Photo 4 shows the location of the false-clock and data-window adjustment potentiometers, R20 and R21, on the Disk-80 circuit board. These are the only user adjustments in the unit. The best method for setting them is to use an oscilloscope and a pulse source. With only IC34 inserted in the board and the +5 V supply on, apply a 50 to 100 kHz clock pulse first to IC34's pin 1. With a scope probe on pin 4, adjust R20 until the one-shot period is 5.4 /is. A similar clock signal is applied to pin 9 of

IC34: that section should be set for a period of 6.0 /ts by turning R21.

In Conclusion

The TRS-80 Model I may no longer be on the minds of the marketing moguls at Tandy Corporation, but the hundreds of thousands of Model I owners will want to keep using it. Now that you know what is inside an expansion interface, you could build one, if necessary.

Correctly assembling an expansion interface from the circuit diagrams of figure 2 is more than just making all the right connections, however. Layout, decoupling, and power

You can extend the usefulness and data entry speed of your TRS-80 by giving it the graphics and menu capabilities of the Bit Pad One digitizer.

With the Bit Pad and proper software, you can generate schematic diagrams; describe sales curves to your computer; enter alphanumeric information by merely touching printed letters on a menu, orenterorderor

inventory information by merely checking boxes on printed forms,

Bit Pad One, complete with stylus, specially designed plug-in TRS-80 interface and power supply cost just slightly over $1,000.

If you don't have a digitizer, you are restricting your TRS-80's abilities. We'll gladly send you a list of distributors who have the Bit Pad One.

^^ mr "cotporalKHi

tttftfrtHi 35 Brentwood Avenue, Fairfield, CT 06430, (203) 384-1344

Now, Bit Pad One™ digitizer makes it easy to add graphics capability to your TRS-80!

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3

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distribution are probably the most critical factors to be considered.

I had to be aware of these same considerations while I was designing the Disk-80, and I had a dilemma when it came time to build the prototype I do for every Circuit Cellar article. The Disk-80 uses fifty-four integrated circuits and 120 resistors and capacitors. The placement of these components is as important, in many cases, as the inclusion of the component.

To eliminate major troubleshooting headaches and make it easier for others to construct this interface, I went straight from my schematic diagram to a printedcircuit board, without breadboarding or wire-wrapping. Besides making it easier for me, the result is an elimination of the concern that experimenters would have about the placement of components and decoupling capacitors and the routing of signal lines. The printed-circuit boards are available from The MicroMint, at the address given in the text box on page 48. The schematic diagram of the power supply is not provided here because the correct sequential application of the voltages depends on the use of the exact transformer and components I specified; the circuit may not work with substitute components. If you really want a schematic diagram and a parts list for the power supply, send a stamped, self-addressed envelope to The MicroMint.

I hope that many of you will take this opportunity to build your own expansion interfaces. ■

Next Month:

Build a low-cost logic analyzer.

References

1. Z80CPU Technical Manual. Zilog Inc, 10460 Bubb Rd, Cupertino CA 95014, 1977.

2. Hoeppner, John. "Interface a FloppyDisk Drive to an 8080A-Based Computer." BYTE, May 1980, page 72.

Editor's Note: Steve often refers to previous Circuit Cellar articles as reference material for the articles he presents each month. These articles are available in reprint books from BYTE Books, 70 Main St, Peterborough NH 03458. Ciarcia's Circuit Cellar covers articles appearing in BYTE from September 1977 thru November 1978. Ciarcia's Circuit Cellar, Volume 11 presents articles from December 1978 thru June 1980.

52

March 1981 © BYTE Publications Inc

Circle 28 on inquiry card.

New iSBX Multimodule boards

Intel introduces a whole new dimension in configuring single board computer systems.

Intel pioneered the concept of flexible microcomputer system design in 1976, with our family of iSBC™ single-board computers interfaced via the Multibus™ system bus—presently accepted as the industry standard.

Now we've extended this wellaccepted concept to board-level design: A new generation of Multimodule boards interface to iSBCs via the new iSBX bus. So now you have a second design option. You can expand systems in large increments with Multibus boards. Or in smaller, more economical increments with Multimodules.

The key to configuration flexibility

The iSBX bus—the first physical/ electrical interface for direct onboard expansion of iSBC systems— assures compatibility between these systems and the emerging Multimodule product line.

Present on all future Intel single-board computers, the iSBX bus saves design time and space, and facilitates fast, easy upgrading. System performance is

New Multimodules and iSBX Bus-compatible iSBCs

I DJOOOOOQOM 0 J

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iSBC 80/24 Single Board Computer

8085A-2 based microcomputer operating at 4.8 MHz (2.4 MHz optional); two iSBX bus connectors; 48 programmable I/O lines; one USART; three programmable timers; programmable interrupt Controller; capacity for 4K-8K bytes RAM; up to 16K EPROM

D Dnona

ISBX 311 Analog Input Multimodule

8 or 16 input channels, voltage protected; 12-bit resolution; ±20 mV to 5V lull scale; 20 kHz samples/sec: compatible with iCS 910 Signal Conditioning Termination Panel

■u)'l

ISBX 328 Analog Output Multimodule 8 channels of analog output; voltage or 4-20 ma current loop; 12-bit resolution; compatible with iCS 910 Screw Termination Panel

HI eF

ISBX 331 Fixed/Floating Point Math Multimodule

Fixed point single- (16-bit) and double(32-bit) precision arithmetic; floating point single- (32-bit) precision functions; floating-to-fixed and fixed-tofloating point conversions: transcendental functions

111 eH

ISBX 332 Floating Point Math

Multimodule

Single- (32-bit) and double- (64-bit)

precision arithmetic; compatible with

proposed IEEE format and existing

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also improved because Multimodules tie directly to the iSBC internal bus. Connection to the iSBX bus is made with a set of rugged connectors— one on the iSBC board, the other on the Multimodule itself.

The new Multimodule family

Multimodules represent a whole new family of plug-in expansion boards. They allow you to add a variety of special performance features to your existing iSBC system. Currently available add-ons are shown below. Soon you'll also be able to add other Multimodules for IEEE 488 GPIB control, communications, peripheral interfaces — and more.

With those modules you can now respond

quickly

to new applications opportunities. Examples? For data acquisition from thermocouples and strain gauges, simply plug in the iSBX 311. For 4-20 ma current loop control, use the iSBX 328. In laboratory control applications, instead of an independent math processor, now you can choose the more

Circle 29 on inquiry card.

economical iSBX 331 or 332 math modules.

Three Multimodule-compatible iSBC boards

Intel's 8-bit iSBC 80/10B, 80/24 and 88/40 single-board computers are the first of many iSBCs to offer iSBX Multimodule expansion iSBX 960-5 connector capabilities. The

first two are improved versions of widely used iSBC boards. (See table).

Custom tailoring, too

For users who want to design their own Multimodule boards, Intel offers iSBX 960-5 connectors. When used in conjunction with the iSBX specifications, this set of connectors lets you create modular boards that meet your own unique requirements.

Available from Intel today are the first six iSBX Multimodules and three iSBX-compatible iSBCs. For further information, or to order, return this coupon or call your local

ntel sales office or distributor. Or

contact Intel at the address below.

int^T delivers solutions.

Europe: Intel International, Brussels, Belgium. Japan: Intel Japan, Tokyo. United States and Canadian distributors: Alliance, Almac/ Stroum, Arrow Electronics, Avnet Electronics, Component Specialties, Hamilton/Avnet, Hamilton/Electro Sales, Harvey, Industrial Components. Pioneer, LA.Varah, Wyle Distribution Group, Zentronics.

Please send information on:

□ iSBX Multimodules D iSBC 80/10B D iSBC 80/24 □ Configuration Guide

□ Other

D Please have a Sales Representative call.

Name

Title/Organization .

Add ress

City/State/Zip_ Phone

Intel Corporation, 3065 Bovvers Avenue, Santa Clara, CA 95051. Telephone (408) 987-8080.

Three-Dimensional Computer

Graphics, Part 1

Franklin C Crow

Department of Computer and Information Science

Ohio State University

2036 Neil Ave Mall

Columbus OH 43210

The process of generating computer representations of three-dimensional structures has been pretty thoroughly worked out over the past fifteen years. Several books on computer graphics describe the necessary steps and commercial graphic software has been available for some time. Recently, three-dimensional graphic software has been made available even to those using microcomputers for personal or recreational purposes.

The software necessary for producing representations of simple shapes is not terribly complicated. In this article, I will try to lay out a few fundamental algorithms that can form the core of a three-dimensional graphics package. However, in order to make sense of these algorithms, considerable explanation will be necessary.

To generate an image of a three-dimensional shape, we have to have a computer-readable representation of the shape. (I will describe a couple of ways to represent shapes.) Then the data for the shape must be transformed to conform to the view of the shape that would be seen from a given point. The data must then be further transformed to fit the shape to the limits of a display surface (video display or plotter). Finally, those parts of the shape that are hidden from view, either because they exceed the limits of the display or because they are hidden by other parts of the shape, must be eliminated.

Getting the Data

The first decision to be made when generating threedimensional data for input to a graphics system is which coordinate system to use. A right-handed Cartesian system is most often used. Standing at the origin of such a

system, the x axis would go to the right, the y axis straight ahead, and the z axis straight up. If we think in terms of a small area of the earth, x would measure longitude (east positive, west negative), y latitude, and z altitude.

Points in this space can be defined as a trio of numbers giving x, y, and z coordinates. A three-dimensional drawing of an object can then be considered a set of lines connecting points in space. An object can be described by listing all its points in the order in which we would draw them. We can then draw the object by "following the dots."

However, we rarely see drawings that are made without ever lifting pencil from paper, so we should add an indicator wherever we move to a point without drawing a line. Thus one format for describing objects consists of a list of sets of numbers. Each set contains three numbers describing a position in space and a command to draw a line to that position or just move to that position without drawing a line, a total of three numbers and a character. An example of this format can be seen in figure la, with the associated data given in table la. The Pascal procedures given in listing 1 (on page 70) read and display objects defined in this format.

This format is fine if we just want to make drawings of objects that appear to be constructed of straight pieces of wire. To represent a solid object, we have to define a surface enclosing the object and therefore need another format. Surfaces are most easily represented if we define them as sets of faces, or polygons.

To define objects made of polygons, we must list the polygons individually. This can be done by listing the coordinates of each vertex (point) of the polygon in clockwise order (as seen from outside the object) around the periphery of the polygon. It is important that all polygons be described consistently since the clockwise order is useful for calculations determining which side of a polygon is facing the viewer.

Photo 1: High-resolution display of solid three-dimensional ob- Photo 2: Low-resolution display of the same objects as in photo jects defined as sets of polygons. 1.

54 March 1981 © BYTE Publications lnc

Circle 30 on inquiry card.

Multi-User

UniFLEX is the first full capability multi-user operating system available for microprocessors. Designed for the 6809 and 68000, it offers its users a very friendly computing environment. After a user 'logs-in' with his user name and password, any of the system programs may be run at will. One user may run the text editor while another runs BASIC and still another runs the C compiler. Each user operates in his own system environment, unaware of other user activity. The total number of users is only restricted by the resources and efficiency of the hardware in use.

Suppor

The design of UniFLEX, with its hierarchical file system and device independent I/O, allows the creation of a variety of complex support programs. There is currently a wide variety of software available and under development. Included in this list is a Text Processing System for word processing functions, BASIC interpreter and precompiler for general programming and educational use, native C and Pascal compilers for more advanced programming, sort/merge for business applications, and a variety ordebug packages. The standard system includes a text editor, assembler, and about forty utility programs. UniFLEX for 6809 is sold with a single CPU license and one years maintenance for $450.00. Additional yearly maintenance is available for $100.00. OEM licenses are also available.

FLEX

TM

Multi-Tasking

UniFLEX is a true multi-tasking operating system. Not only may several users run different programs, but one user may run several programs at a time. For example, a compilation of one file could be initiated while simultaneously making changes to another file using the text editor. New tasks are generated in the system by the 'fork operation. Tasks may be run in the background or 'locked' in main memory to assist critical response times. Intertask communication is also supported through the 'pipe' mechanism.

UniFLEX is offered for the advanced microprocessor systems. FLEX, the industry standard for 6800 and 6809 systems, is offered for smaller, single user systems. A full line of FLEX support software and OEM licenses are also available.

Box 2570, West Lafayette, IN 47906 (317) 463-2502 Telex 276143

""UniFLEX and FLEX are trademarks of Technical Systems Consultants, Inc.

A solid object is customarily defined as a group of adjoining polygons. Since neighboring polygons share vertices along common borders, objects can be more compactly defined by first listing all the vertices belonging to the object and then listing polygons by the numbers of the vertices they use. An example of this sort of format is seen in figure lb, with data in table lb. The procedures in listing 2 read and display objects as a set of polygons.

Now that we know how to read and display objects, where do we get the data describing the objects? The simplest way is to dream it up. After all, much of the joy of computer graphics lies in creating imaginary worlds. Take a piece of graph paper and draw front and side views of an object you'd like to represent. Then measure the vertices of the object by counting squares from some point of origin on the paper. The front view will give you the x and z coordinates, and the side view will give you the y coordinate (see figure 2).

People who are involved in creating three-dimensional graphics generally build software to aid in designing objects. For example, a program to generate surfaces of revolution is relatively easy to write. Then shapes such as wine glasses and vases are easy to make. A surface of revolution can be defined by a sequence of points follow

Photo 3: Removal of hidden surfaces can be clearly observed in this display generated on a custom graphics display unit connected to a Digital Equipment VAX 11/780.

Photo 4: Transformation of a scene due to a change in the location of the eyepoint as well as transformation of the objects within the scene. Compare with photo 3.

ing a path up one side of the surface. The points then sweep out a surface by rotating about a central axis. Surfaces of revolution are widely used in computer imagery. More advanced techniques make use of high-speed interactive graphics terminals (costing $20,000 to $150,000) in conjunction with elaborate software to define and modify shapes. See the papers by Crow and Parent (listed among the suggested readings at the end of this article) for examples of this approach to data gathering.

Defining a View of Some Objects

Once data describing an object is available, it is time to figure out how to look at it. In the real world, when we look at an object, what we see is determined by our viewpoint and the position of the object. How can we emulate this in an imaginary world?

We want the choice of viewing an object from any viewpoint. Therefore we must have an algorithm that will move the vertices of the object to the proper position, given a particular viewpoint. The input to this algorithm consists of two points in space: the position from which we are looking and the position at which we are looking. I will refer to these as the eyepoint and the center of interest, respectively.

In order to understand how such an algorithm works, we need to know more about how to move objects about in an imaginary world. So far I have defined an object within its own space or frame of reference. Now we would like to arrange a number of objects in a scene, each in a different position and orientation.

Changing the position of an object is relatively simple. Using the longitude, latitude, altitude model of space, we can move an object east by simply adding some positive number to the x coordinates of all its vertices. To move an object north, we add some positive number to all its y coordinates. To move an object up or down, we change all its z coordinates. This process is called translation.

Similarly, to change the size of an object we multiply all its coordinates by the same number. This is called scaling. To make an object twice as large in every dimension, we multiply all coordinates of every vertex by two. Thus, changing the position or size of an object is relatively straightforward. Rotating an object or combining successive operations, however, requires more sophisticated techniques.

Objects can be moved about quite elegantly using techniques provided by matrix algebra. We devise a sort of template that is filled in to provide the operation desired. Filled templates, called transformation matrices, can then be combined to provide complicated operations.

A template, or matrix, consists of sixteen positions (four rows by four columns). Numbers loaded into a matrix are combined with vertex coordinates to yield updated coordinates by matrix multiplication. The first column of the matrix affects only the x coordinate and therefore contains all the numbers that define the updated x coordinate. The second column treats the y coordinate similarly, and the third column handles the z coordinate. The fourth column is for completeness, to make things more elegant. It also allows us to pull some fancy tricks such as finding the inverse of a transformation. I won't use the fourth column in this article, however.

A vertex is "transformed" by the matrix as follows: To get the new x coordinate, the old x coordinate is

56 March 1981 © BYTE Publications Inc

Don't play games with your company's money.

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We call it VIP. The Vector Intelligent Partner. And with a price of just $3695, you can't get more computer for your money.

VIP has all the assets and none of the liabilities of other entry level systems. It starts off with a lot more disk capacity. It has the same computational power, uses the same software as our larger systems, and can be upgraded at any time. So you avoid the expense of new hardware and software when you outgrow your current system.

You'll beabletodo low cost word processing, mail list sorting, database management and accounting. You can even do software development.

VIP is perfect for salesmen, real estate brokers, insurance agents, small business owners and corporate department heads. Because at Vector, improvingyourbusinessisthe best way to improve our business.

For information contact Vector, 31364 Via Colinas, Westlake Village, CA 91362. Or call 213/991-2302.

Economy Sized Computers

Circle 31 on inquiry card.

BYTE March 1981

57

la

lb

M

1.0

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d

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-1 .0

.00

d

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-1.0

1 .0

d

1.0

-1 .0

1 .u

d

1.0

1 .0

1.0

d

1 .0

1 .0

-1.0

d

1 .0

-1.0

-1.0

d

1.0

-1.0

1 .0

M

-t.o

-1.0

.00

d

-1 .0

-.00

1 .0

d

-1 .0

1 .0

1 .0

d

-1.0

1.0

-1.0

j

u

A

- 1 . V

-1.0

-1 .0

M

-1.0

-.00

1.0

d

-.00

-'1.0

1.0

M

-1.0

1 .0

-1.0

d

1.0

1 .0

-1.0

H

1.0

1 .0

1.0

d

-1.0

1.0

1 .0

10

7

1 .0

-1 .0

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1.0

-1 .0

-1.0

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(NufiF'ts NuriFuivs.) -1.0 -1.0 1.0 .00 1 .0 1 .0

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i .0

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i

4 9

10

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10

Table 1: Data for an object defined as a set of lines (table la) and for an object defined as a set of polygons (table lb). In table la, the "m" and "d" in the first column mean "move to" or "draw to" the point with x, y, and z coordinates as given in the next three columns, respectively. In table lb, the first line gives the number of points (10) and polygons (7) in the shape. The next 10 lines give the point number (1 thru 10) and the x, y, and z coordinates of the point. The last seven rows describe the seven polygons: the first number gives the number of points making up that polygon, and the rest of the numbers on that line give the point numbers (as described by the point description lines) that make up the polygon. Both tables la and lb describe the shape shown in figure lb.

(1,1,1)

Figure 1: Three-dimensional object displayed as a set of straight lines defined by 10 points (figure la) and a set of polygons defined by using the same points (figure lb). See table 1 for associated data.

multiplied by the top number in the first column, then added to the product of the old y coordinate and the second number in the first column. The sum is then added to the product of the old z coordinate and the third number in the first column. Finally, the whole thing is added to the bottom number in the first column. The new y coordinate can be obtained by combining the second column and the old vertex coordinates in the same way. Similarly, the new z coordinate is produced using the third column. The Pascal procedure in listing 3 (on page 70) transforms a vertex.

Under the rules stated above, the bottom row of the matrix holds numbers that translate the object. A number at the bottom of the first column is added to all x coordinates to move an object east or west. Similarly, numbers at the bottom of the second and third columns affect the y and z coordinates. To scale objects, we enter the scaling factor along the top-left-to-bottom-right diagonal of the matrix. The top-left number in the matrix is multiplied by the old x coordinate to yield the new x coordinate. Similarly, the second number in the second column multiplies the y coordinate and the third number in the third column multiplies the z coordinate.

Rather than trying to explain rotations in the limited space here, I will simply illustrate how to fill in the matrix. Trying a few examples by hand should convince you that rotations work. Simple rotations are those that rotate an object about one of the axes of our space. For instance, to rotate an object about the z axis by an angle A, use the following matrix:

cos(A)

sin(A)

0

0

sin(A)

cos(A)

0

0

0

0

1

0

0

0

0

1

Note that this matrix leaves the z coordinate unchanged, which is what we would expect from a rotation about the z axis. Furthermore, a rotation through a zero angle leaves everything unchanged since the cosine of zero is 1 and the sine of zero is 0.

I always use the convention that a positive rotation occurs in a counterclockwise direction looking in the negative direction along the axis about which you are rotating. This means that if the thumb of your right hand is pointed in the same direction as that axis, your fingers will curl in the direction of positive rotation. Keeping

58 March 1981 © BYTE Publications Inc

TH 7TT

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IF YOU CAN FIND A LOWER PRICE IN THIS MAGAZINE ON ANY OF THE ITEMS LISTED BELOW, DEDUCT 3% FROM OUR COMPETITOR'S PRICE, THAT'S OUR PRICEl (BUT IF YOU DON'T SEE IT. CALL FOR A PRICE—WE WILL BEAT EVERYBODY!)

S-100 HARDWARE APPLE HARDWARE

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Floppy Disk Controller (Model

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4 Port Serial I/O (Model

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Z-80 CPU (Model 2810) $249

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SD Systems Versa Floppy $279

Expando RAM $CALL

Microsoft Z-80 Soltcard $259

SSMAIO $165

SYMTEC Apple Light Pen $219

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Centronics Printer Interface (Model 7728) . .$99 MOUNTAIN HARDWARE:

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INTROL/X-10 $180

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MUS1CSYSTEM $499

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Lobo Drive $CALL

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•FREE shipping on all orders over $20. Visa and Master Cat ly answer any questions on all of our hardware, software, handling charges when arriving at never undersold price

d accepted. All never undersold offers good as supply lasts. Please add 2.00 for all COD orders. Please call for items not listed. We gladand supply needs. Quanitily discounts available. School purchase orders accepted. Please remember to figure competitors shipping and

Circle 32 on inquiry card.

High Technology

We make our

competition

obsolete

with Information Master.™

Information Master™ is the sophisticate of software packages, but it also speaks your language. Its uncomplicated Englishspeaking design makes it easy to learn. No programming knowledge is necessary. Put it in your Apple II* and you're ready to go.

High Technology's Information Master organizes and prints everything from mailing lists to stock market data. Specify what records to store, type in the information, and Information Master organizes, calculates, stores and reports. Design your own reports and labels. Information Master is revolutionary in its adaptability and comes with a simple step-by-step instruction manual. Its screen layouts are designed to show you maximum information for easy operation. Information Master is so smart it stops mistakes that our competition lets you make.

If your computer dealer doesn't have Information Master, see one who does.

High Technology's perfect complement to Information Master, Data Master,TOallows you to change your mind months later

without redoing all the work you've already

High Technology, Inc.

Software Products Division P.O. Box B-14665 8001 N. Classen Blvd. Oklahoma City, Okla. 73113 405 840-9900

'Apple II is a trade name o\ Apple Computer. Inc

I I I

I I

I

1 1 1 1

z

FRONT

VIEW

I

SIDE VIEW

I

,

i

•

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1 1

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1 1

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Figure 2: Vertices for objects to be displayed in three dimensions may be measured from front and side views laid out on ordinary graph paper.

track of such things requires a strong sense for visualizing space. When in doubt, I sketch things with pencil and paper.

To rotate about the x axis, use the following matrix:

1 0 0 0

0 cos(A) — sin(A)

0

0 sin(A) cos(A)

0

0 0 0

1

To rotate about the y axis, use the following matrix:

cos(A)

0 sin(A)

0

0 1 0 0

— sin(A)

0 cos(A)

o

0 0 0

1

Combining these fundamental rotations results in even more interesting rotations.

Note that all transformations occur relative to the origin of the given space. Thus, to rotate or scale an object without changing its position, we must first be sure that it is centered on the origin. Therefore, a rotation or scaling "in place" (ie: without changing position) requires a translation to center on the origin, followed by rotation or scaling, then a second translation back to the original position.

Once all the objects in a scene have been transformed to the desired positions and orientations, a view from a given eyepoint in the direction of the object of interest is simulated by an additional transformation that places the object in the desired position and orientation. This simulation can be achieved by combining a few rotation matrices.

In the first step, we move everything so that the eyepoint lies at the origin of the space and the center of interest lies on the y axis, or due north. To do this, we translate the eyepoint to the origin and apply the same matrix to all the other data. The translation matrix is as follows:

1

0

0

0

0

1

0

0

0

0

1

0

ye.X

-Eye.Y

— Eye.Z

1

where Eye.X, Eye.Y, and Eye.Z are the x, y, and z coordinates of the eyepoint.

60 March 1981 © BYTE Publications Inc

Circle 33 on inquiry card.

The Perfect Fit

The Micromodem II data communications system and the Apple II* computer. What better combination to maximize the capabilities of your personal computer!

This popular direct connect modem can transmit data between an Apple II and another Apple II, a terminal, another microcomputer, minicomputer or even a large time-sharing computer anywhere in North America. The Micromodem II has unique automatic dialing and answer capabilities which further increases the communications possibilities between the Apple II and another computerorterminal.

You can send and/or receive messages or data when you are out of your office, home or out of town. Your branch business locations can communicate with each other regarding inventory and other matters over the phone. Or you can communicate with friends across the country. And you can access information utilities like the SOURCE for various business and personal applications.

The Micromodem II consists of two parts. One part includes the printed circuit board which holds the Micromodem II, ROM firmware and the serial interface. The board plugs directly into the Apple II providing all the functions of a serial interface card plus programmable auto dialing and auto answer capabilities. The on-board ROM firmware enables the Micromodem 11 to operate in any of three modes to perform different tasks-terminal mode, remote console and program control mode.

The other part of the Micromodem II datacomm system is a Microcoupler which connects the Micromodem board and Apple II to a telephone line. The Microcoupler gets a dial tone, dials numbers, answers the phone and hangs up when a transmission is over. There are none of the losses or distortions associated with acoustic couplers. The Microcoupler is compatible with any North American standard telephone lines and is FCC-approved for direct connection in the U.S. It works with standard dial phone service or Touch-tone service.

The Micromodem II is completely compatible with Bell 103-type modems. Full and half-duplex operating modes are available as well as speed selectable transmission rates of 110 and 300 bps.

Why not increase your Apple ll's capabilities by outfitting it with the sophisticated Micromodem II data communications system? The Micromodem II is available at retail computer stores nationwide. For the store nearest you, call or write:

©Hayes

Circle 34 on inquiry card.

Hayes Microcomputer Products Inc.

5835 Peachtree Corners East, Norcross, Georgia 30092 (404) 449-8791

*" Micromodem II is a trademark of Hayes Microcomputer Products, Inc.

* Apple II is a registered trademark of Apple Computer Inc.

The Micromodem II can also be used withthe Bell & Howell computer.

The <* &**

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Computer Generated Graphics Made Simple

Zgrass is an exciting user-oriented language developed for real time interactive graphics.

Zgrass software includes a full screen text editor; point, line, box, ellipse, pattern display and fill graphics routines; full math capabilities; full string manipulation and array capabilities; both interpretive and compiled modes of execution.

• The Datamax® UV-1 is the only advanced graphics system featuring the Zgrass language.

• Using much of Bally's® commercial video game electronics, the UV-1 shares the same reputation forruggednessand reliability.

• 64K bytes of memory (16K EPROM, 16K screen RAM, 32K user RAM).

• ZSO microprocessor; floating point math processor; custom video graphics processor; custom input/output processor with 4 A/D converters and 3 channel sound synthesizer.

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A rotation about the z axis can now be used to move the center of interest in a northerly direction. In particular, we move the center of interest into the plane defined by the y and z axes. The angle of rotation is found by passing the center of interest through the eyepoint translation matrix defined above and then applying the following formulas:

cos(A) = Cl.Y/V(Cl.X)2 + (Cl.Y)2 sin(A) = Cl.X/V(Cl.X)2 + (Cl.Y)2

where A is the angle of rotation and Cl.X and Cl.Y are the x and y coordinates of the translated center of interest, respectively (see figure 3).

The process of moving the center of interest onto the y axis is completed by rotating the object about the x axis, using the following formulas:

cos(A) = C2.Y/V(C2D2 + (C2.Z)2 sin(A) i C2.ZA/(C2.Y)2 + (C2.Z)2

where C2.Y and C2.Z are, respectively, the y and z coordinates of the translated and rotated center of interest (see figure 4).

Because all this is done with the intention of displaying the resulting coordinates on a flat surface, one more transformation is called for. It is useful to think about the display surface (video display, plotter, etc) as a space in which the x axis measures width, the y axis height, and the z axis depth. We can place our transformed coordinates into this space by interchanging the y and z axes, using the following matrix:

1

0

0

0

0

0

1

0

0

1

0

0

0

0

0

1

Given coordinates for an eyepoint and a center of interest, we can use the matrix multiply procedure to combine the above operations into a single orientation for displaying a view of the scene. The procedure in listing 4 (on pages 70 and 72) builds such a matrix. We refer to the resulting arrangement of a scene as the eyespace.

Clipping

Once all the data in the scene is transformed to the eyespace, we must decide how much of the scene fits on the display. The display can be thought of as a window into an imaginary world. Things such as the size of the window and our distance from it determine what can and cannot be seen: We can use the edges of the window and the origin of the space (ie: the eyepoint) to define planes that clip parts of polygons not visible through the window (see figure 5).

The clipping window defines the field of vision in much the same way that the film gate and lens in a camera limit the field captured by the film. The window can be defined as a polygon corresponding to the boundaries of the display as we expect to view it. For example, if we are in the habit of looking at a 12-inch video display from a distance of 16 inches or so, the clipping window should be a rectangle about 6 inches high and 8 inches across, located 16 inches from the eyepoint.

Circle 35 on inquiry card.

Circle 36 on inquiry card.

from

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DISCOVERY

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MULTIPROCESSOR

THE World Class Multiprocessor

From Guangzhou. China to Norwich. England. From Banphai. Thailand to Pasadena, California. A proven record of performance and reliability in installations throughout the World makes the DISCOVERY MULTIPROCESSOR the international choice in multiuser microcomputer systems.

WORLD CLASS SOFTWARE WORLD CLASS HARDWARE

Our Distributed Processing Operating System, dpos/2 ", resides in the Service Processor, establishing a CP/Mt environment for each user and managing access to the shared system resources. Multiuser facilities are provided for print spooling, for interprocessor communication and for private, public and shared-update files. Several processors can be employed concurrently by a single user via the enhanced batch submit facilities. And with DISCOVERY all CP/M compatible programs will execute without modification, thus protecting yoursoftware investment.

The ACE 64K Distributed Processing single board Computer, the dpc-180 " gives the DISCOVERY MULTIPROCESSOR its unique architecture. One DPC is dedicated to each user providing exclusive use of the onboard Z-80, 64K ram and serial I/O. Shared storage is provided by an expanded DPC used as the Service Processor. Additional users can be added at any time by simply inserting additional DPC's into the standard S-100 bus— up to 16 in a single chassis!

f CP/M is a registered TM of Digital Research. Inc.

Whatever your requirements, Whatever your language. No matter how you say it — DISCOVERY is THE World Class Multiprocessor.

The ACE DISCOVERY MULTIPROCESSOR dedicates a complete. 64K Z-80 Distributed Processing single board Computer, the dpc-180'" to each user. An expanded DPC coordinates all of the system activities.

Multiuser mainframes with 192K ram start at under $6000. The 64K dpc-180" is priced at $1395. Immediate delivery. A complete line of standard peripherals including a 26M byte hard disk subsystem can be supplied on request. Dealer and OEM inquiries are invited.

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Figure 3: Graphical representation of calculating the rotational angle about the z axis in computing the eyespace matrix.

C2.Z

Figure 4: Graphical representation of calculating a rotation about the x axis.

The first step of the clipping process is to define the planes to be clipped against. Planes can be defined by four numbers, the coefficients of an equation of the following form:

AXx + BXy + CXz + D = 0

We can simplify this equation somewhat since all the planes we are interested in pass through the origin. For all planes passing through the origin, the fourth coefficient, D, equals zero.

Our window can then be characterized by a sequence of sets of three numbers, each set describing one plane. Listing 5 produces the coefficients of the plane equations needed for clipping. Input is assumed to be a polygon. Each clipping plane is determined by three points: the eyepoint and the two endpoints of an edge from the input polygon. This assumes that polygon vertices are taken clockwise as seen from the eyepoint and that a "lefthanded" (width, height, depth) eyespace is used.

Once we have the clipping-plane coefficients, they can be applied to all the vertices of a polygon to find out which lie inside and which lie outside the field of view. The clipping coefficients are applied to a vertex using the following formula in Pascal style:

Distance : =

Vtx.X Vtx.Z

Clp.X Clp.Z

+ Vtx.Y * Clp.Y +

Figure 5: Representation of how a viewing window "clips" portions of polygons lying outside the pyramid defined by the window and the eyepoint.

This operation (known as a vector dot product) yields a distance measure that tells us how far inside or outside the viewable area the vertices lie. Negative numbers indicate that a vertex lies outside, positive numbers that a vertex lies inside. If distances for all clipping planes applied to all vertices of a polygon are positive, it is completely visible. If distances for all vertices and any of the clipping planes arenegative, the polygon is entirely outside the window and thus not visible (assuming the clipping window is convex). If some distances are positive and some are negative, we may have to cut the polygon into inside and outside portions.

The procedure in listing 6 takes a polygon and clips it by a set of plane coefficients stored in a second polygon array. Each plane is tested in turn against each polygon vertex. Vertices lying inside (on the positive side of) a plane are copied to a temporary polygon array. Where two adjacent vertices are found to lie on opposite sides of a plane (ie: D1XD2<0.0, meaning the signs of the distances are different), the intersection point of the clipping plane and the edge connecting the two vertices is copied to the temporary array. When all the vertices of the polygon have been clipped against one plane, the temporary array is copied back into the input array and clipped against the next plane. This process eliminates parts of polygons lying outside an unbounded pyramid emanating from the eyepoint and delimited by the window polygon.

Displaying

Any polygon found to lie within the field of vision must be displayed. An additional transform is necessary to take the coordinates of the eyespace to the coordinates used by the display device, the "screen space." Furthermore, a division is necessary to achieve the appearance of

64 March 1981 © BITE Publications lnc

It's all

relative,

especially

your career.

How far you go in your career is directly related to your own attl ities and ambitions. At the same time, where you work is just as important. Wot all companies are the same. At COMSAT, we pride ourselves on the creative latitude we offer our professionals. We don't stifle imaginations.

We encouiage you to develop new skills and abilities as you work with some of the best people in their respective fields. The opportunities for self-growth and professional fulfillment are virtually unlimited at COMSAT. You'll be involved in some of the most important and exciting projects taking place in the world today, in all areas directly and indirectly related to high technology.

We're the company that pioneered the INTEISATglobal communications system, which today keeps more than 100 nations in touch. And we're constantly exploring and developing new programs and applications for satellite technology.

With every new advance in space technology, COMSAT continues to lead and grow. IbUowing INTEISAT came COMSTAR and M ARISAT, two industry-leading commercial communications systems. COMSAT also is now the U.S. representative to INMARSAT,

the most recent international communications organization providing satellite communications to the maritime community. COMSAT'S latest projects include telecommunications products

manufacturing, integrated CAD/ CAM systems, domestic and global technical and support services, environmental monitoring, satellite-to-home subscription television Additionally, COMSAT laboratories performs supporting research and development in communications satellite technology and related areas.

Our rapid expansion has created numerous career openings in many diversified engineering disciplines including communications, RF system, spacecraft design, mechanical, microwave, sr. transmission systems, manufacturing, sales, test, and modem design, as well as technicianrelated areas and marketing.

We offer excellent salaries and benefits. If you want to know more about us, simply forward your resume, indicating your area of interest. Well be in touch with you promptly. Write to Senior Employment Representative, Department 81-IRC, COMSAT, 950 L'Enfant Haza, S.W., Washington, D.C. 200S4.

AT*

l$0 COMSAT

An Equal Opportunity • Affirmative Action Employer.

BYTE March 1981

65

perspective (ie: objects in the distance should be smaller). This transform can take the form of a scaling matrix as follows:

Scale.X : = DotsAcross * WinDist/WinWidth Scale.Y : = DotsDown * (V3) * WinDist/WinWidth

The matrix is then:

Scale.X

0

0

0

0

Scale.Y

0

0

0

0

1

0

Middl.X

Middl.Y

0

1

In the above transform, DotsAcross is the number of dots across the display, DotsDown the number of lines on the display from top to bottom, WinDist the distance to the window in eyespace, Win Width the width of the window, and Middl.X and Middl.Y are the x and y coordinates of the middle of the display (in screen space, usually DotsAcross/2 and DotsDown/2). The factor (V3) takes into account that the standard video display is V3 as wide as it is high (the aspect ratio). It is assumed that the window has the same proportions as the display.

Nonrectangular windows require a more careful calculation. If the maximum width of the window is less than V3 times the maximum height, another number must be substituted for the window width in the above calculations. That number should be the maximum of the window width and V3 times the window height. Of course, if we use a display with a different aspect ratio, the width of the display divided by its height should replace the V3.

The procedure in listing 7 divides the x and y coordinates of each vertex by its z coordinate to achieve the perspective effect, then applies the transformation to display coordinates directly, rather than using a matrix transformation.

This completes the process of computing an image of objects with all data shown, as though the objects were made of pieces of straight wire. Next, we look at how to achieve the appearance of solid objects capable of hiding each other.

Hidden Faces

There are two methods that allow solid objects to hide parts of themselves or other objects. The first uses the plane equation of each polygon to determine whether or not it lies on the far side of its object. If it does, the polygon is clearly hidden by closer parts of the object. The second uses a clipping procedure similar to the one described earlier to remove parts of faces that are hidden by closer faces.

In everything that follows, polygons are assumed to be convex. Restricting things in this way simplifies the task considerably at a very small increase in the cost of preparing object descriptions.

Earlier in the article, I stressed the importance of taking the vertices of all polygons in a consistent order, usually clockwise as seen from outside the object. Many objects are closed surfaces, meaning that the inside of the object can be seen only by passing through the surface. In fact, if we choose to do so, we can construct all objects as closed surfaces for display purposes.

In any event, if a polygon appears on the screen with its vertices in counterclockwise order, we must be seeing it from the inside. If we are looking at a closed surface from the inside, some other part of the surface must lie between us and the polygon in question. Therefore, when making pictures of solid objects made of closed surfaces, we can immediately reject any polygons appearing in counterclockwise order.

Earlier we used planes for clipping by evaluating the positive or negative distance from a point to the plane. Similarly, when the eyepoint lies on the positive side of the plane of a polygon, the vertices of that polygon appear in clockwise order. When on the negative side, they appear in counterclockwise order. Some of the procedures developed earlier can be used to determine whether or not a polygon "faces the eyepoint."

Three of the vertices of the polygon define a plane. Here we can use the procedure developed earlier for finding a plane defined by two window vertices and the eyepoint. Use the three points to define two lines. If the two lines are treated as direction vectors (subtract one endpoint from the other), the two vectors can be passed to the procedure, which then returns coefficients for a plane parallel to the polygon and passing through the origin. These coefficients, when used in a dot product with one vertex of the polygon, yield a number that tells us on which side of the polygon the eye lies. The function in listing 8 does the job.

If a closed convex surface is being displayed by itself, the above process is adequate to produce the image with only visible faces shown. However, if the surface is not convex, or there is more than one object involved, further procedures are necessary.

Those polygons surviving the clipping procedure and the "eye-facing" test can be sorted by their distance from the eyepoint. We base the sort on the average of the z coordinates of each polygon in turn. If all polygons are roughly the same size, no two polygons intersect each other, and no two polygons lie close to each other in nearly parallel planes, the sort order will allow us to eliminate hidden parts of polygons. Most scenes involving separated, reasonably simple objects will conform to the above conditions.

Since the polygons must be transformed, clipped, and tested for "eye-facing" one by one, it makes sense to use an insertion sort to order the polygons displayed. A list of polygons to be displayed is built by inserting each new polygon description (number of vertices and position in vertex array) in the already sorted list of previous polygons. A binary search can be used to reduce the search time for finding the insertion point. The procedure in listing 9 implements a binary insertion sort. Note that polygon vertices are stored in an array in contiguous groups. The z coordinate of the first element of the group is used to hold the average z coordinate of the polygon for subsequent tests.

Sorting is a major part of nearly all hidden-line and hidden-surface algorithms. For a thorough discussion of sorting and other aspects of hidden-surface algorithms, see the paper by Sutherland and others listed in the suggested readings. Also see the third volume of Donald E Knuth's The Art of Computer Programming for a thorough treatment of sorting in general.

Text continued on page 82

66 March 1981 © BYTE Publications Inc

The best news since CP M... customizable full screen editing

As a serious computer user you spend much of your time editing, whether it be for program development or word processing. Make the best use of your time with the help ofVEDIT, an exceptionally fastand easytouse full screen editor. VED1T is a highly refined and proven editor which is easy enough for novices to learn and use. Yet its unequalled set of features also makes it the choice of computer professionals. And because VED1T is user customizable, it adapts to your keyboard, hardware, applications and preferences.

In VED1T, the screen continuously displays the region of the file being edited, a status line and cursor. Changes are made by first moving the cursor to the text you wish to change. You can then overtype, insert any amount of new text or hit a function key. These changes are immediately reflected on the screen and become the changes to the file.

VED1T has the features you need, including searching, file handling, text move and macros, plus it has many special features. Like an 'CJNDO' key which undoes the changes you mistakenly made to a screen line. And a mode which allows a programmer to enter all textin lower case and let VED1T convert the labels, opcodes and operands, but not the comments, to upper case. The screen writing is almost instantaneous on a memory mapped display or can use your CRT terminal's editing capabilities. Disk access is very fast too, and VEDIT uses less than 12K of memory. The extensive 70 page, clearly written manual has sections for both the beginning and experienced user.

Totally User Customizable

Included is a setup program which allows you to easily customize many parameters in VEDIT, including

the keyboard layout for all cursor and function keys, screen size (up to 70 lines, 200 columns), default tab positions, scrolling methods and much more. This setup program requires no programming knowledge or 'patches', but simply prompts you to press a key or enter a parameter.

The CRT version supports all terminals by allowing you to select during setup which terminal VEDIT will run on. Features such as line insert and delete, reverse scroll and reverse video are used on 'smart' terminals. Special function keys on terminals such as the H19, Televideo 920C and IBM 3101, and keyboards producing 8 bit codes or escape sequences are also supported.

New Features and Support

The new release includes disk write error recovery, indent and undent keys for structured programming, and the ability to insert a specified line range of another file at the cursor position. Versions for MP/M and the Apple 11R SoftCardRare now also available.

Ordering

Specify the CRT version, your video board or microcomputer, the 8080/Z80 or Z80 code version, and disk format required.

Standard Package: Disk and manual $110

Manual: Price refunded with software purchase 15

VISA and MASTER CARD Welcomed. Attractive Dealer Terms.

CP/M and MP/M are registered trademarks of Digital Research, Inc. Apple 11 is a registered trademark of Apple Computer, Inc. SoftCard is a trademark of Microsoft.

North Star • Heath H8/H89 • SuperBrain • Apple 11 SoftCard • Sorcerer • TRS-80 Model I TRS-80 Model 11 • MP/M • Most other CP/MRSystems with CRT or Memory Mapped Displays

CompuView Products Inc.

618 Louise, Ann Arbor, Michigan 48103 • Telephone (313) 996-1299

Circle 38 on inquiry card.

BYTE March 1981

67

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ADM — 3A Industries favorite dumb terminal lor some very smart reasons. ADM — 3A + NEW from Lear Siegler. CALL' IT S HERE! - It is the new Intermediate Terminal from Lear Siegler. Call for details.

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Reader & Printer $845.00 /' •■■"■-. Quad RAMS for the 41-C £ (Equivalent to four Memory Modules all packed into one) $95.00

COMMODORE

COMPUMART has delivered more Commodore computers in the US. than any other dealer. Call us now for low prices and special deals. NEW FOR PET. Visicalc (Need 32K & a disk drive) $199. - Word Pro I. $29.95 Word Pro 2. $99.95 - Word Pro 3. $199.95 - Word Pro 4. $299.95. Educators Take Notell Comma dore has extended its 3 for 2 deal until 6-30-81 This means that any educational institution which buys two Commodore computers will receive a third absolutely FREE. Call our sales department for complete details.

NEW! The PMC-80. The new

computer that's software compatible with the TRS-SO. Level 11 16K at $645.

ACCESSORES FOR PMC - 80 EXP-lOO S-lOO Bus Expander Disk, Printer, RS232 I/O $410.

S-32K S-lOO Bus 32K RAM Board

for EXP-lOO $295.

CAB-40 Cable 12" long ribbon cable

for EXP-lOO $25.

Visit our giant

ANN ARBOR STORE

1250 North Main Street Ann Arbor. Michigan

SEND FOR OUR FREE CATALOG

EXCLUSIVE from CompuMart! Special Oiler. Zenith Color Video Monitor tor $379!

NEW FROM SANYO - Four Great Monitors at Low CompuMart Prices. Sanyo's new line of CRT data display monitors are designed lor the display of alphanumeric or graphic data.

9" Sanyo Monitor $169.

12" Sanyo Monitor $289.

12" Sanyo Monitor with green

screen $299.

13" Sanyo Color Display Monitor

$495.

COMPUMARTs MicroQex 65 System for your AIM Includes Adapter Buffer Module w/4-slot module slack. 8K RAM module, 16K PROM/ROM module. Asynchronous communications Interface, and Power Supply $1,299 Call or writer for our complete Microflex 65 brochure ROCKWELL ATM 65 Our AIM system includes. 4K AIM with BASIC interpreter assembler, Power Supply, Cassette recorder & Enclosure $799.

4K AIM-65 $499.

PL65 High Level Language $125. Paper lor the AIM (roll) $2.50

Rockwell's 4-slot Motherboard (sale) $175.

HP-85

Hewlett-Packard's Personal Computer for Industry. This extremely portable computer features extended BASIC to solve your problems quickly and efficienlly along with an advanced graphics system to enhance communication. HP-85 ACCESSORIES We carry H.P. Peripherals (Disk Drives to Graphics Plotters) Enhancements: (BASIC Training. General Statistics, Financial Decision Math, Linear Programming $95 ea); HP-85 Accessories. (Enhancement ROMs, ROM drawer. Overhead Transparency Kit). Supplies. (Plotter Pens. Tape Cartridges).- Interface Modules (HP-IB Interlace, HP-IB Interconnect Cables, Serial (RS-232C) Interface Module), We can get your every HP peripheral made for the HP-85. CALL FOR COMPLETE DETAILS & SPECS.

COMPUMART exclusive ATARI SPECIALS

ATARI 800 Personal Computer System — Comes with 800 operators Manual. 16K Rany Men^ oiy module, lOk ROM Operating System. Power j Supply. TV Switch^** ,

Box QP

$950.S^

PERIPHERALS

Atari 410 Program Recorder

$89.95

Atari 810 Disk Drive

(SlOO off with purchase) $699.95

NEW Dual Disk double density

$1499.95 825 Printer (Centronics 737)

$995.00 RS232 Interface w/Cable $249.95 NEW! Light Pens $74.95

NEW! Visicale lor Atari $199.00 Educators Take Note. Atari has extended its 3 lor 2 deal until 630-81 Any educational institution that buys two Atari 800's will receive an Atari 400 computer absolutely FREE. Call our sales dept lor complete details.

IMPORTANT ORDERING INFORMATION All orders must include 4% shipping and handling. Mass. residents add 5% sales tax. Michigan residents 4% tor sales tax Phones open trom 8.30 am. to 7:00 p.m., Mon-Fn: 11:00 a.m. to 4:00 p m. Sat. RO's accepted Irom Dun & Bradstreet rated companies - shipment contingent upon receipt ol

signed purchase order. Sale prices valid lor month ol magazine date only - all prices subject to change without notice. Our Ann Arborretail store is open 11:00 a.m. to 7:00 p.m. Tues.-Fri.. 10:00 a.m. to 5:00p.m. Saturdays,

APPLE n

We carry the most complete inventory ol Apple computers, peripherals, and soltware. CALL! Oui Best Selling Apple System Save over S250 on our most popular Apple System. System includes a 48K Apple 11, Apple Disk, DOS3.3, & Controller, and a Sup R. Mod RF Modulator. List S2120.

COMPUMART Sale Price, $1875.

SOFTWARE FROM APPLE

Apple Plot. The perfect graphic

complement lor Visicalc.

S70

Dow Jones News & Quotes

S95

Adventure (Uses 48K)

$35

DOS Tool Kit

S75

Apple Fortran

S200

Tax Planner

$120

FROM PERSONAL software

Visicalc

$149

Desk Top Plan

$99

NEW FROM MUSE

The Voice

$39.95

Super Text $99.00

Address Book

$49.95

Miscellaneous Apple n

Accessoriesi

Easy Writer (80 col. need a

Videx)

$249

Easy Mover

$49

Easy Mailer

$69

NEW from Apple lot the Apple 11,

Dos 3.3 Convert disks to 16 sector iormat lor 23% more storage and taster access $60.

NEW to: the Apple n From MicroSolt

16K RAM Board $195.00

FORTRAN $175.00

COBOL $750.00

Card Reader trom Mountain Hardware $1,195.00

HLRes Dump lor 460 Printer trom the Computer Station $49.95

HARDWARE ACCESSORIES FOR APPLE

Silenlype Printer w/x lace $635 Super Sound Generator (mono) $159 (stereo) $259

Light Pen $249

X-IO Controller (plugs into paddle port) $49 Mountain Computer — Expansion accessories lor your Apple Introl - lO System $289 Super Talker $299 The Music System $545 ROM plus board w/Keyboard filter $199 Clock Calendar $280 16 Channel A to D Converter $350

Apple Expansion Chassis $650 ROM Writer $175

From VIDEXI— Video Term.

80 CoL x 24 line. 7x9 Matrix plug in compatible board lor the Apple n. Price $325 without graphics EPROM With graphics EPROM $350.

S.S.M. Serial 8c Parallel Apple Interlace $225

ABTs Numeric Key Plan $110 Calilornia Microcomputer Keyboard $195

Apple in

Space won't allow us to give you the details and specs on this already lamous new computer. Call our expert sales lorce today lor tuD details - they can answer any questions. We have complete system packages in stock. COMPUMART carries all Apple CI related soltware and hardware. If you need an Apple ffl call COMPUMART now.

Apple III In

Stock Now for Immediate Shipment.

COMPUMART has been serving the computer needs of industry since 1971.

We stock, for immediate shipment, only those products from the finest micro-computer manufacturers.

And any product, except software, can be returned within lO days for a full refund even if you just change your mind,

We also honor all manufacturers' warranties. Our expert technicians will service any product we sell that cannot be better, or faster, serviced by the manufacturer's local service center.

Call us for more information on products, product configuration and service. Our phones are open Monday thru Friday, 830 a.m,to 700 p.m. and Saturday HOO a.m. to 400 p.m.

We have a staff of highly knowledgeable sales people waiting to hear from you, and to help,

Because service is what we're all about.

-^Sss?'

800-343-5504

In Mass. Call 617-491-2700

i-, ■ it/—i i Circle 39 on inquiry card.

^COMPUMART

f65 BENT STREET, DEPT. 114, RO. BOX 568 CAMBRIDGE, MA 02139

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ook what's happened to

HIPL0T

TM

$1,385*

$1,850"

(T: I

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1-1 1

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It's grown into a complete family of quality low cost digital plotters

In just two short years, The HIPL0T has become the most popular digital plotter among small systems users. With a record like that, what can we do for an encore? WE'VE INTRODUCED A COMPLETE LINE OF HIPL0TS...with a model suited for just about every plotting application.

The HIPL0T DMP Series is a new family of digital plotters with both "standard" and "intelligent" models available with surface areas of 81/2" x 11" (DIN A4)and 11" x 17" (DIN A3). For the user needing a basic reliable plotter, we have the "old standard" DMP-2 (81/2" x 11") and the "new standard" DMP-5 (11" x 17"). For those needing a little more capability, there are the DMP-3 (81/2" x 11") and the DMP-6 (11" x 17")-both

TM HIPLOT and DM/PL are Trademarks of Houston Instrument

Yes, they are UL listed!**

microprocessor controlled and providing easy remote positioning of the X and Y axes (perfect for the OEM). For those who want this intelligence plus the convenience of front panel electronic controls, we've provided the DMP-4 (81/2" x 11") and the DMP-7(11" x 17").

The "standard" plotters come complete with an RS-232-C and a parallel interface. The "intelligent" DMP plotters accept data from either an RS-232-C or Centronics data source. For the "standard" plotters, software is available from our ever expanding "Micrographic Users Group." The "intelligent" HIPLOTs use our exclusive DM/PL™ language which mininimizes plot software to a fraction of that normally as

houston instrument

GRAPHICS DIVISION OF

BAUSCH&LOMB

Circle 40 for literature

Circle 41 to have representative call

sociated wth digital plotting.

With the new DMP Series, high quality digital plotting can now be a part of your system. It just doesn't make sense to be without this valuable tool when there is a DMP plotter with the plot size, speed and capabilities that are exactly tailored to your specific needs...and your budget.

Prices for the DMP series range from $1,085* to $1,985*.

For complete information contact Houston Instrument. One Houston Square, Austin, Texas 78753. (512) 837-2820. For rush literature requests, outside Texas call toll free 1-800-531-5205. For technical information ask for operator #5. In Europe contact Houston Instrument, Rochesterlaan 6, 8240 Gistel, Belgium. Telephone 059/27-74-45.

'U.S. suggested retail prices only. ■•□MP 2,3 and 4 UL listed DMP 5, 6 and 7 UL listing pending

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Circle 42 on inquiry card.

STOP PLAYING GAMES

nan

IlllUlKilW

Corvus Transforms the Personal Computer into a Powerful Business Tool.

In business, professional offices, and schools throughout the world, thousands of Corvus intelligent peripherals bring mass storage, increased speed, and multi-user capability to a variety of microcomputers. Current applications include accounts receivable and payable, medical records, mailing lists, inventories, word processing, insurance, mathematics and science, and other large and complex files.

Corvus proven Winchester disk technology provides 10 to 80 million bytes of capacity, fully compatible with your current operating system. This is up to 500 times the capacity of a floppy disk.

The Corvus CONSTELLATION links up to 64 computers in a state-of-the-art multi-processor network. It provides shared mass storage, pipes for inter-computer communication, and system spooling for sharing of peripherals such as printers. Performance far exceeds that of larger and more expensive networks.

Backup data protection and archival storage are provided by the Corvus MIRROR (Patent Pending), a lowcost backup using standard video cassette recorders.

Contact your local Corvus dealer for the full story about these innovative new products. .

r CORVUS SYSTEMS

* 2029 OToole Avenue

'f San Jose, California 95131 (408) 946-7700/TWX 910-338-0226

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74 March 1981 © BYTE Publications lnc

SYNCHRO-SOUND ENTERPRISES ANNOUNCES OUR

NEW MICRO-COMPUTER SYSTEMS CENTER

We are one of the oldest, most experienced, highly dedicated

micro-computer systems houses in the metropolitan New York area...

the ORIGINAL Computer People who KNOW computers and offer

you EVERYTHING you need in small computer systems.

Call, write or stop in ...compare Price, Quality, Delivery, Service and you'41 see why you don't have to look anyplace else!

AAA SYNCHRO-SOUND

\u/ ENTERPRISES, INC. THE COMPUTER

r V 125 MINEOLA AVENUE, PEOPLE ROSLYN HEIGHTS, N.Y. 11577

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VISIT OUR SHOWROOM WORKING MODELS ON DISPLAY

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APPLE SOFTWARE

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Asteroids in Space 19

Autostart ROM Pkg 59

Battleship Commander 19

Bill Budges Space Game Album 39

Bill Budges 3-D Graphics/Tool 39

Bill Budges Trilogy of Games 29

Cashier Retail Mgmt. Sys 199

Checkbook Cassette 19

Contrib. Vols. 1-5 w/man 29

Controller Bus. Pkg 514

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Desktop Plan Sftwe 79

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DOS 3.3 Upgrade 49

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Extender Board 27

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TO ORDER: Phone orders invited using Visa, Mastercard, or hank wire transfers. Visa & MC credit card service charge ol 2%. Mail orders may send charge card number (include expiralion date), cashiers check, money order, or personal check (allow 10 business days forchecks to clear). Please include phone number. Inc'ide 3% ($5.00 minimum) shipping, handling, and insurance in USA. Shipments within Calif, add 6% sales Tax, Foreign orders include 1% handling — shipped freight collect. Foreign orders over S1000 allow 3 weeks extra and include S25 license fee. All equipment Is in factory cartons with the manufactures warranty. Equipment is subject to price change and availability We ship the same day on most orders. No C.O.D.s accepted. Retail store prices differ from mail order prices

(714) 579-0330 • MAIL TO: 1251 broadway, el cajon, ca. 92021

Circle 43 on inquiry card.

fHoTTiWT?^

AUTHORIZED APPLE SALES & » r, , , „ , „ - ■■ ,

SERVICE V K. ^ II II I -^V ./X. A. II

ITIOM

▼

■Kl/ERS

The Byte Covers shown at left are available as Collector Edition Prints. Each full color print is:

• 11" X 14" including a 1W border.

• Part of an edition strictly limited to only 100 prints.

• Personally inspected, signed and numbered by the artist, Robert Tinney.

• Accompanied by a Certificate of Authenticity.

• Carefully packed and shipped first class.

• Priced at $20, plus $3 ($6 overseas) for postage and handling. If Set 1-4 or Set 5-8 is ordered, the price for all 4 prints is only $70.

To order, use the coupon below. Visa or MasterCharge orders may call Toll Free.

i i Pli I tio

Please send me the following Collector Edition Byte Covers and Certificates of Authenticity.

Qty. Cover Amount

#1-7 Bridges ol Konigsberg $20

#2-Fun and Games S20

#3-Homebrew $20

#4-Software Mirage $20

#5-Computer Engineering $20

#6-Total Eclipse $20

#7-Computer Hardware $20

#8-Perspectives $20

No/s 1-4 $70

No.'s 5-8 $70

Post. & hand. ($3 in US , $6 overseas) $

Total

D I have enclosed check or money order

□ Visa D MasterCharge

Card #

Expiration Date

Send my print(s) to: Name

Address.

City

State

-Hip

-800

TOLL

854-,

B*S*"

24

<°°°li2/Ext9lO

Ho"»s*ZTy*

DAYi

■ 910

days

Mail this coupon to:

robert tinney graphics

1864 N. Pamela Dr. Baton Rouge, LA

FOR W^rrT—-^ 7°815

week.

Let Crystal Be Your Guide on the Road to Adventure

I APPLE J

those systems with sound capability, our games have Crystalsonics — a new some truely superlative hires graphics. In fact. Sands of Mars offers 3-D grapr maps of Martian terrain.

cept in tone generation. For Apple and Atari there are

Wi" now serve over 30 countries around the world. Dealership and distributor inquiries are welcome. Special rates are available on larger orders. We have 48 hours delivery to anywhere in the continental United States. We are also looking for experienced programmers and new game software. Our royalty terms are extremely generous. If you have what you consider to be a quality product that you would like to have marketed please give us a call. If you would like to be a member of the Crystal User's Club and be eligible to receive free user contributed software, please submit a program of any type and a $10.00 membership fee. In return you will receive a Crystal Membership Card, a copy of The House of Usher, and a year's subscription to Crystal Vision.

HOUSE OF USHER — Wander through a haunted house. Rooms and LASAR WARS — Crystalsonics - hires graphics - protect the planet

scenery in 15 color lo-res graphics. We offer a $100.00 prize to the first earth from a full scale alien invasion. Over three types of invading craft

person to solve the mystery. Over 200 monsters, objects and perils. and hundreds of approach simulations. The games speaks for itself.

$24.95 $29.95

GALACTIC QUEST — Crystalsonics - hires graphics -the ultimate WORLD WAR III — Crystalsonics-hires graphics-for you war game

space adventure. Vegan warships attack and fire in real time Simula- freaks, this is it! Iran and Irag - nuclear missiles - hires 3 scene bat

tion. Land on and trade with over 64 star systems in 3 galaxies. Allow tlefield - demolition squads - tanks - strategy. Custom designed for two

6-12 hours for play. $29.95 arm chair generals. Save-the world from nuclear holocaust! $29.95

SUMER — Travel back through time to ancient Sumeria in the middle BENEATH THE PYRAMID — Crystalsonics - hires graphics - brand

east. You are given 10 years as king to restore this kingdom to prosper- new! Explore the pyramids and miles of winding secret tunnels beneath

ity. Plant, war, consult the astrologers - very hard to beat! $19.95 them. Enter at the Sphinx and find the hidden treasure chamber. All in

hires with very aggressive monsters and many many perils. To win you must find the golden cat and your way out!!! $29.95

LITTLE CRYSTAL — Especially designed anthology for children from ages 5 to 80. Includes Mr. Music which turns your Apple into an organ of sorts, gunk where two weird monsters shoot it out and many other educational as well as entertaining programs for children. True unique addition for kids who always feel left out of Dad or Mom's computerizing. $39.95

SANDS OF MARS — What we at Crystal believe to be the finest adventure game available to date. In addition to hires graphics and super tone routines where the user's system will support it, this game provides landing simulation, animation, and revolutionary 3-D graphics, it is the ultimate in space adventure and may take several weeks or months to play. It is the Oydessy of the Starship Herman on its maiden flight to Mars. The initial liftoff is animated and paddle controlled. The flight through space is in Hires 3-D Graphics with many animated scenarias. You must land your starship on Mars. It will lack enough fuel and supplies for a return voyage. You must lead your party through hundreds of Hires maps of Martian terrain and subterrainian passages. You then will secure adequate resources for take off, navigate your ship back to earth and attempt a successful touchdown. There is a mystery buried in the ancient city of Lemuria beneath the sands of Mars. We offer a $100.00 prize to the first space gamer to discover it. Good luck! $39.95

For more information you may write or call: Crystal Computer, 12215 Murphy Avenue, San Martin, California 95046

Circle 44 on Inquiry card.

(408)683-0696

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80

March 1981 © BYTE Publications Inc

Circle 45 on Inquiry card.

Suddenly Radio Shack's New TRS-80 Color Computer is

Even Better!

New Extended Color BASIC. Here's an advanced TRS-80 Color Computer that includes a 16K ROM Extended BASIC with advanced graphics, eight brilliant colors, and sound, for an unprecedented low price! You can draw ine lines, circles, rectangles, boxes and more with easy-to-use one-line commands. Four graphic modes with two color sets allow up to 49,152 programmable screen points (pixels). There are 255 separate tones for music or sound effects. All this on a 16K RAM machine (including video memory) loaded with the dynamic features a serious programmer demands. You get a 32x16 screen, multi-character variable names (two significant), editing, tracing, user-definable keys, 255-character string arrays, floating point 9-digit accuracy, and even machine language routines.

Priced at Only $599, the TRS-80 Extended Color BASIC Computer is useful, entertaining and educational. Yet using it can be as simple as plugging in one of Radio Shack's instant-loading Program Paks. Come in and see what's already available. The computer attaches to your TV, or our own $399 TRS-80 Color Video Receiver. For just $24.95, you can add a pair of joysticks which add flexibility to games and video displays. A built-in serial interface lets you attach a printer or a modem. A tutorial Color BASIC instruction manual is included, of course.

More Good News. Extended Color BASIC is also available as an upgrade kit ($99) for the 4K Color Computer (16K RAM required— $119). There's a modest installation charge fa each kit.

New TRS-80 VIDEOTEX Software (with the modem shown below) offers Color Computer owners quick, affordable access to many kinds of information and data services. For example, our exclusive agreement with CompuServe® Information Service gets you local, national and international news, weather and sports from 11 area newspapers and the Associated Press News Service; information on over 32,000 stocks and bonds; an educational reference service; entertainment news and reviews; nationwide Electronic Mail with other users; and much more! You'll also access Dow Jones Information Services for Wall Street news, stock quotes and more.

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491.

Text continued from page 66:

Once the polygons are sorted, we can apply a clipping algorithm in a reversed sense. We will remove any parts of polygons lying inside a closer polygon as seen on the display. Starting with the closest polygon and working outward, each polygon will be clipped by all its predecessors. Remember, keeping things simple will require that polygons be convex. (Nonconvex polygons can always be broken into a set of convex ones.)

In order to use a polygon for clipping, its edges must be converted to clipping planes. Therefore, once any part of a polygon is determined to be visible, the entire polygon is subsequently converted to plane coefficients using the same procedure used earlier to convert the window description for clipping.

Since each polygon edge, once clipped, can be displayed without further treatment, it is easiest to clip each edge individually. This process is not as straightforward as it may seem. A polygon may clip an edge into two parts, each of which must then be subsequently clipped by the remaining polygons. Of course, any of the later polygons may further divide one of the edge fragments. This sort of situation is best handled using recursion. Therefore, the procedure given in listing 10 recursively clips a polygon by all closer polygons and flags visible polygons for use in subsequent clipping. Hidden polygons obviously need not be used to clip more distant polygons.

Conclusion

The preceding procedures provide essentially

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everything needed to display three-dimensional line drawings representing solid objects modeled by polygons. An effort has been made to make the procedures concise. This has been done at the expense of efficiency and sometimes, perhaps, even at the expense of clarity. I have assumed the availability of a display of some kind that can be used to draw lines. Most systems capable of full graphics provide software for generating lines.

In the interests of completeness, Part 2 will present a complete program incorporating the procedures described above. I have been able to use it, somewhat crudely, with a semigraphic terminal (Zenith H-19) and the UCSD Pascal system (see photo 2) and, more satisfyingly, with a 500-line raster display and a Pascal interpreter running under the UNIX operating system (see photos 1, 3, and 4; photos are on pages 54 and 56).

If you have a serious interest in three-dimensional graphics, a full understanding of what has been presented here is heartily recommended. In addition, you should consult the suggested readings listed below for more material. Many people have spent time on the problems discussed in this article and have published useful articles describing other ways to produce computer-generated three-dimensional images.

In addition to line drawing images, much computer graphics is now displayed using the features offered by raster displays. Quite realistic imagery is possible, offering a vast array of possibilities well beyond those described here. There is much work to be done in this area yet, so if you are interested, go to it!B

Acknowledgments

Mary Lieb handled text-editing and formatting chores. Some of the software development and all the higher-resolution computer-generated images were done on equipment supplied in part by the National Science Foundation (equipment grant § MCS 80-06322) and in part by the Ohio State University.

Suggested Reading

Newman, W and R Sproull, Principles of Interactive Computer Graphics, 2nd edition, McGraw-Hill, 1978. The classic text on computer graphics—some consider it difficult, but you must read it if you are serious about the subject.

Rogers, D F and J A Adams, An Introduction to Computer Graphics, McGraw-Hill, 1977. A cookbook approach to the subject with many useful algorithms listed in BASIC.

Giloi, W K, Interactive Computer Graphics, Prentice-Hall, 1978. An introductory textbook with a somewhat different approach than that of the two books above.

Knuth, D E, The Art of Computer Programming: Volume 3, Sorting and Searching, Addison Wesley, 1973. A treasure trove of algorithms and analyses of algorithms—a very important book.

Sutherland, I E, et al, "A Characterization of Ten Hidden-Surface Algorithms," ACM Computing Surveys, March 1974. A very informative explanation of the extant hidden-surface algorithms of the time. Computing Surveys is available in most technical libraries.

Crow, F C, "A System for the Design of Three-Dimensional Objects," Proceedings of the ACM National Conference, 7977. A system for designing three-dimensional shapes involving simple curved surfaces, available from the Association for Computing Machinery, 1133 Avenue of the Americas, New York NY 10036.

Parent, R, "Three-Dimensional Object Synthesis," Proceedings of SIGGRAPH '76, 1976. A more comprehensive system for building three-dimensional objects. See also the proceedings of the annual SIGGRAPH conferences for the last five years or so, which contain papers describing most of the interesting work done in recent years—the best way to keep up with what's going on. Available from the Association for Computing Machinery, listed above.

82

March 1981 © BYTE Publications Inc

Circle 52 on Inquiry card.

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Product Review

The Micro Matrix Photopoint Light Pen

Stephen B Gray, 219 W 81 St, Apt 7C, New York NY 10024

Because it's called a light pen, and because of the way it seems to be used, many people have the incorrect impression that a light pen does something directly to the image on the video screen. In actuality, it's the other way around. A light pen contains a photodiode that detects the movement of a point of light on the video screen, determines the coordinates of that point, and branches to a specified action for that point.

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For example, if you're playing tic-tac-toe, you only have to point the light pen at the square in which you want to place your X. With a scan limited to nine areas on the video screen, the photodiode detects which area you're pointing to and puts an X in that square.

Applications

As hinted above, one of the most popular applications for the light pen is games. Instead of pressing a key, you need only point the pen. This eliminates having to memorize which key does what.

Another popular application is the fast selection of items in a screen menu. Some advanced graphics programs use light pens and menus. A screen may present a selection of shapes along one side, for example. You touch one, then touch the point on the screen where you want the computer to place the shape. Using small menus along the bottom of the screen, you control the size and rotation of the shapes to create complex subjects.

Micro Matrix Photopoint

One of the several light pens on the market for the Radio Shack TRS-80 is the $19.95 Photopoint from Micro Matrix, POB 938, Pacifica CA 94044. (The Photopoint is also available from Quality Software, 6660 Reseda Blvd, Suite 105, Reseda CA 91335.) The documentation notes that "The light pen allows the user to use their CRT as a programmable keyboard where your own BASIC program (or a prepackaged one) can be written to ask questions and the operator just points at the appropriate answer. No more fumbling with keyboards! The Photopoint can be used with any DOS and with any size memory (must be a Level II TRS-80)." Fortunately, the rest of the documentation is not as confusing as that first sentence.

For your $19.95 you receive a light pen that looks like a slender felt-tip pen, with a two-part cable which connects to a 9 V battery and to your recorder. You also receive a cassette with backgammon, tic-tac-toe, Word Sampler, and a light-pen subroutine; documentation containing another game and a listing of the subroutine is also included.

84

March 1981 © BYTE Publications Inc

Circle 46 on inquiry card.

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BYTE March 1981 85

(la)

Photo 1: Three of six demonstration programs included with the Micro Matrix Photopoint light pen: x, y plotting (la), backgammon (lb), and tic-tac-toe (1c). The light pen requires a TRS-80 Level 11 with 16 K bytes of programmable memory.

Using the Photopoint

The pen's miniature plug is connected either to your cassette recorder's auxiliary or microphone jack. When plugged into the auxiliary jack, the pen responds to graphics but not to normal text. When plugged into the microphone jack, the pen is sensitive to both text and graphics (the suggested mode for most uses).

One of the main reasons for Photopoint's comparatively low price is that it uses the amplifier in your tape recorder. To turn on the amplifier, remove any cassette from the recorder; then, while holding in the record interlock pin (at the rear of the cassette compartment), press the RECORD and PLAY buttons simultaneously. The only thing left to do is connect a 9 V battery to the battery- clip, and you're set to go.

After loading the light-pen subroutine, you will see a menu from which you can choose any of six demonstration programs.

The light pen doesn't read instantly; you have to wait for the scan to pass the square you're aiming at, and then a bit longer for the software to react. One good way to get a feel for what is going on is to place a broadcast-band AM radio near the TRS-80 keyboard. You'll hear something like a "dit-dit-dit-un-pah" as the computer recognizes a flashing square. Since it can't "read" a static square, the program flashes the squares in sequence to give the photodiode a target to pick out.

The first two demonstration programs are similar, with a series of eight squares arranged horizontally (in program 1) and vertically (in program 2). When any square is touched by the light pen, the number of the square (1 thru 8) is printed on the screen. The third demonstration program uses the same principle—this time with a series of fifty blocks; the fourth scans eight randomly placed squares; and the fifth (see photo la) plots lines and curves by lighting an asterisk when a pair of squares along the x and y axes are touched.

The backgammon program (see photo lb) allows you to use the light pen to roll the dice, redraw the board, or play a new game. Or, you can move by aiming the light pen at FROM and TO selection squares.

Tic-tac-toe (see photo lc) is played with a large field and double-size characters. You play against the computer, and indicate a square by pointing the pen to the right of the number in that square.

The computer puts an X in the square you select, then an O in the square it selects. The process continues until the computer detects that the game has been won or drawn.

The fourth program on the cassette is Word Sampler. You or the computer enters a sentence. Then you point the light pen at any word, and the computer displays that word above the sentence, starting at the left margin and continuing with further words you select. Thus you can construct a new sentence by rearranging the words of the old one.

The fifth program is called Cube Chase. After you key in eight lines, you point the light pen at a white square on the screen, and the square quickly moves elsewhere.

If you plug the light pen into the auxiliary jack, remove the black plastic plug from the microphone jack, and then whistle or snap your fingers, the cube will change its position on the screen. (This works on my CTR-41, although perhaps not on some other cassette recorders.)

86 March 1981 © BYTE Publications Inc

The first personal computer forunder$200i ^^>

The Sinclair ZX80. A complete computeronly $199.95 plus $5.00 shipping.

Now, for just $199.95, you can get a complete, powerful, full-function computer, matching or surpassing other personal computers costing several times more.

It's the Sinclair ZX80. The computer that "Personal Computer World" gave 5 stars for 'excellent value.'

The ZX80 cuts away computer jargon and mystique. It takes you straight into BASIC, the most common, easy-to-use computer language.

You simply take it out of the box, connect it to your TV, and turn it on. And if you want, you can use an ordinary cassette recorder to store programs. With the manual in your hand, you'll be running programs in an hour. Within a week, you'll be writing complex programs with confidence.

All for under $200.

Sophisticated design makes the ZX80 easy to learn, easy to use.

We've packed the conventional computer onto fewer, more powerful LSI chipsincluding the Z80A microprocessor, the faster version of the famous Z80. This makes the ZX80 the world's first truly portable computer (6W x 8W x Vk" and a mere 12 oz.). The ZX80 also features a touch sensitive, wipe-clean keyboard and a 32-character by 24-line display.

Yet, with all this power, the ZX80 is easy to use, even for beginners.

Your course in computing.

The ZX80 comes complete with its own 128-page guide to computing. The manual is perfect for both novice and expert. For every chapter of theory, there's a chapter of practice. So you learn by doing—not just by reading. It makes learning easy, exciting and enjoyable.

You'll also receive a catalog packed with items that can make your ZX80 even more useful. Including 27 program cassettes, from games and home budgeting for just $6.95, to Sinclair's unique Computer Learning Lab (a workbook, six cassettes with 100 lessons, and two cassettes for storing programs).

ZX80's advanced design features.

Sinclair's 4K integer BASIC has performance features you'd expect only on much larger and more expensive computers. ■ Unique 'one touch'entry. Key words

(RUN, PRINT, LIST, etc.) have their

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and save memory space.

■ Automatic error detection A cursor identifies errors immediately to prevent entering programs with faults.

■ Powerful text editing facilities.

■ Also programmable in machine code.

■ Excellent string handling capability—up to 26 string variables of any length.

■ Graphics, with 22 standard symbols.

■ Built-in random number generator for games and simulations.

Sinclair's BASIC places no arbitrary restrictions on you—with many other flexible features, such as variable names of any length.

And the computer that can do so much for you now will do even more in the future. Options will include expansion of IK user memory to 16K, a plug-in 8K floatingpoint BASIC chip, applications software, and other peripherals.

Order your ZX80 now!

The ZX80 is available only by mail from Sinclair, a leading manufacturer of consumer electronics worldwide.

To order by mail, use the coupon below. But for fastest delivery, order by phone and charge to your Master Charge or VISA. The ZX80 is backed by a 10-day moneyback guarantee, and a 90-day limited warranty

Price includes TV and cassette connectors, AC adaptor, and 128-page manual.

All you need to use your ZX80 is a standard TV (color or black and white). The ZX80 comes complete with connectors that easily hook up to the antenna terminals of your TV. Also included is a connector for a portable cassette recorder, if you choose to store programs. (You use an ordinary blank cassette.)

The ZX80 is a family learning aid. Children lOand above will quickly understand the principles of computing—and have fun learning.

To order call toll free: 800-543-3000.

In Ohio call: 800-582-1364.

Ask for operator #508.

which can be extended by 12 months under Sin- Phones open 24 hours a day, 7 days a week, clair's extended service program for $25.00.

Sinclair Research Ltd., 475 Main St., P.O. Box 3027, Wallingford, CT 06492.

I

• To: Sinclair Research Ltd., 475 Main St., P.O. Box3027, Wallingford, CT 06492.

| Please send me ZX80 personal computer(s) at $199.95 each (US dollars), plus $5

I shipping. (Your ZX80 may be tax deductible.) For Conn, deliveries, add sales tax. Send me Computer Learning Lab(s) at $49.95 each.

I Register me for extended service program(s) at $25.00 each. I enclose a check/money orderpayable to Sinclair Research Ltd. for$

I Name

Address.

■ City

| Occupation.

. State.

. Zip _

-Age.

I

Intended use of ZX80

Have you ever used a computer? D Yes D No Do you own another personal computer? □ Yes D No

tJ

The explanation is simple: The TRS-80 receives its information from the Photopoint light pen through tape port 255. The program makes the recorder think the light pen is a microphone. A sudden change of impedance occurs when a scanning blip of light is detected by the pen's photodiode.

Photo 2: Quick Draw enables use of the light pen to draw or erase figures in a 48 by 64 graphic field. More complex drawing programs may be written but the manual gives no information on how to do this.

MICROSTAT NOW AVAILABLE FOR CP/M*

MICROSTAT, the most powerful statistics package available for microcomputers, is completely file-oriented with a powerful Data Management Subsystem (QMS) that allows you to edit, delete, augment, sort, rank-order, lag and transform (11 transformations, including linear, exponential and log) existing data into new data. After a file is created with DMS, Microstat provides statistical analysis in the following general areas: Descriptive Statistics (mean, sample, and population S.D., variance, etc.). Frequency Distributions (grouped or individual). Hypothesis Testing (mean or proportion). Correlation and Regression Analysis (with support statistics). Non-parametric Tests (Kolmogorov-Smirnov, Wilcoxon, etc.). Probability Distributions (8 of them), Crosstabs and Chi-square, AN OVA (one andtwo way). Factorials, Combinations and Permutations, plus other unique and useful features.

MICROSTAT requires 48K, Microsoft Basic 80 with CP/M and is sent on a single-density 8" Disk. It is also available on 5" diskettes for North Star DOS and Basic (32K and two drives recommended), specify which when ordering. The price for Microstat is $250.00. The user's manual is $15.00 and includes sample data and printouts. We have other business and educational software, call or write:

«H ECOSOFT

P.O. Box 68602

Indianapolis, IN 46268

(317)283-8883

* CP/M is a registered trade mark of Digital Research.

[master charge]

Micro Matrix is also reportedly planning an interface for Sargon II so you can play chess using a light pen. Also planned are a number of chase games.

PENBASIC

For $14.95, Micro Matrix is offering Steve Bjork's PENBASIC, which adds ten new commands to Level II BASIC. Among the most interesting are:

• P = &NOTE(exp) produces a tone on the cassette output with (exp) ranging from 0 (highest pitch) to 255 (lowest pitch).

• P = &PEN PEEK tests to determine if the light pen is pointed at a lighted part of the display.

• P = &PEN performs a full screen search for the pen position. If the pen is not found, a — 1 is returned; if it is found, PRINT @ (position) is returned.

• P = &PEN USING searches for the pen only at the points specified in the expression.

• P = &PEN FOR searches for the pen at the points defined in a one-dimensional integer array.

Using PENBASIC, any of the 1024 locations on the TRS-80 video display can be detected. The four-page PENBASIC manual explains eight of the ten commands and includes brief examples of using them within programs. The manual appears to be written for those with a good knowledge of BASIC. In fact, two of the functions aren't explained at all.

Along with PENBASIC, the demonstration tape contains two programs: Quick Draw and Line of Five.

Quick Draw (see photo 2) enables you to use the light pen to draw and erase figures in a 64 by 48 graphic field. You use related key commands to draw, erase, position the cursor, load and save to and from tape, and end the program. Turning on a square can take several seconds (sometimes longer). Quick Draw is described as a "simple drawing program," which hints that more complex (and, perhaps, faster) programs can be written. The manual gives no clues how to do this.

Line of Five is described as "the first in a series of application programs for PENBASIC." It's a simple game of capturing five squares in a row before the computer does. The computer plays a fairly aggressive game but can be beaten. ,

The Micro Matrix Photopoint light pen and PENBASIC make a useful package for examining light-pen applications. What makes it even more attractive is that the price is the lowest on the market. ■

Why Can't a Light Pen Use the Raster Scan?

The Exidy Sorcerer is probably the only home computer that can use the raster scan, according to Mike Banks, president of Micro Matrix. The Sorcerer uses the microprocessor to control the video and sets up a counter to keep track of the vertical scan. The TRS-80 has no such counter, and thus cannot ask, as the Sorcerer can, "What was the count at the moment I saw the light?" In PENBASIC, when the PEN PEEK command detects a lighted part of the display, it is merely looking to see if the tape-recorder output, at port 255, is high or low.

88

March 1981 © BYTE Publications Inc

Circle 47 on inquiry card.

Circle 48 on inquiry card.

SayAhh...

Our New grafixPLUS™ 80-column printer opens wide for easy servicing.

Introducing the newest members of our grafixPLUS,M family—the DP-9000 Series 80/132 column printers—built on the same tradition of quality printout, solid design and low cost of ownership established by our 132/220 column DP-9500 Series.

A Case for Serviceability

Not that is comes up often, but want to get inside? Simple. Just remove a few screws and the clamshell case swings open exposing all major components. This easy access plus built-in self-test and minimum component count yields an MTTR of onehalf hour. The 9-wire print head replacement's even simpler... two screws and it's out. Without opening the case. And without a service call.

Performance Plus

The DP-9000 Series prints the full ASCII 96 character set, including descenders and underlining, bidirectionally, at up to 200 CPS. Number of columns, can go up to 80 or 132, depending on character density—switch or data source selectable from 10 to 16.7 characters per inch. And all characters can be printed double width. The print head produces razor-sharp characters and high-density graphics with dot resolutions of 72X75 dots/inch under direct data source control. <•

Interface Flexibility

The three ASCII compatible interfaces (parallel, RS-232-C and current loop) are standard, so connecting your computer is usually a matter of plug

it-in and print. Also standard are: a sophisticated communications interface for printer control and full point-to-point communications, DEC PROTOCOL, and a 700 character FIFO buffer. An additional 2K buffer is optional. When you're ready for a printer (or several thousand), look into the grafixPLUS DP-9000 Series from Anadex—you'll find an open and shut case for quality. Contact us today for details, discounts and demonstrations.

...the plus in printers

...close please.

SALES OFFICES: San Jose, CA (408) 247-3933

Fullerton. CA (714) 8710501 • Wakefield, MA (617) 245-9160 • Austin, TX (512) 327-5250

ANADEX, INC. • 9825 DeSoto Avenue • Chatsworth. California 91311. U.S.A. • Telephone: (213) 998-8010 • TW ANADEX, LTD. t Dorna House. Guildford Road • West End. Woking. Surrey GU24 9PW. England • Tel: Chobham (09905) 6333 • Telex: 858762 AN*"

What's Inside Radio Shack's Color Computer?

Tim Ahrens, Jack Browne, Hunter Scales

3501 Ed Bluestein Blvd

Austin TX 78721

The only similarity between Tandy Corporation's new Color Computer and its older brother —the original TRS80 —is the name. Even the microprocessor has been changed. In an apparent breakaway from the Z80, the Color Computer uses the Motorola MC6809E microprocessor as the workhorse of the new silver box. In fact, when we opened the enclosure, we didn't see any semiconductors that weren't made by Motorola.

The Color Computer is totally self-contained—no bulky separate power transformers —and the only cord, the one to the wall socket, has a standard three-prong connector. It can work with any color or black-andwhite television set and has provisions for joysticks, a 1500 bps (bits per second) cassette interface, and an

Number

Device

Part

of Pins

Quantity Number Description

MC6809E

40

1

1

Microprocessor

MC6821

40

2

2, 3

Parallel Interface Adapter

MC6883

40

1

4

Synchronous Address Multiplexer

MC6847

40

1

5

Video Display Generator

MCM68A364

24

2

6, 7

8 K-byte Read-Only Memory

MCM4027

16

8

8 thru

15 4 K-bit Programmable Memory

MC74LS138

16

1

16

3-bit Decoder

MC74LS02

14

1

17

Quad 2-lnput NOR Gate

MC74LS244

20

1

18

Octal Buffer/Line Driver

MC74LS273

20

1

19

8-bit Latch

MC14050B

14

1

20

Hex Noninverting CMOS Buffer

MC14529B

16

1

21

Dual 4-Channel Analog

MC1372

14

1

22

Color-Subcarrier Modulator

MLM339

14

1

23

Quad Voltage Comparator

MC723C

14

1

24

Voltage Regulator

MC78M12

3

1

25

Voltage Regulator

MC79M12

3

1

26

Voltage Regulator

MC79M05

3

1

27

Voltage Regulator

UM1285-8

NA

1

28

ASTEC Video Modulator

Table 1: List of integrated

circuits used in the TRS-80 Color

Computer.

Large-scale integration

reduces the number of

devices necessary to

build

in sophisticated capabilities, and

improves ri

liability.

All circuits used are manufactured by

Motorola.

expansion connector for preprogrammed game cartridges.

Our aim in this article is to expose the insides of the computer and show what makes it run. Using this information, you should be able to expand the Color Computer in a number of ways, with a minimum of expertise. We will also describe the graphics interface so that do-ityourself graphics routines should be a piece of cake.

System Hardware

Taking the cover off is simply a matter of removing seven screws and lifting the lid. Be warned, however, that Tandy takes a dim view of owners fooling around with their hardware. Opening the case voids the warranty on the machine (one of the screws lies under a paper label that gives this warning).

The first surprise is that the entire computer is built on a single printed-circuit board —including the power supply. Most of the digital circuitry lies inside an RFI (radio-frequency interference) shield — this was probably necessary to get FCC (Federal Communications Commission) Type Approval, but it also helps to give a clean display. To get a look at the parts, simply pry off the top of the shield.

There are only twenty-four DIPs (dual in-line packages) in the system and they are all made by Motorola. (The parts list is shown in table 1.) The machine comes stuffed with 4 K-byte memory circuits; but there is a simple way to change these to 16 K-byte devices and a tricky way to get 32 K bytes of on-board memory —more on this later.

While we do not yet have a schematic diagram, the block diagram in figure 1 should be sufficiently detailed to allow a thorough understanding of the system. There are four basic sections:

•the microprocessor

•the video-display circuitry

•the memory

•the other I/O (input/output) devices (keyboard,

cassette, serial port, and joysticks)

The microprocessor is Motorola's advanced 8-bit machine, the MC6809E. It was designed to support today's high-level languages, including the Extended

Text continued on page 96

90 March 1981 © BYTE Publications Inc

IF YOU CAN

miT A MINUTE,

WE CAN S/yE

YOU %i

iii

With the Starwriter™ Daisy Wheel 25 cps printer from C. Itoh.

A business letter, written on a 45 cps word-processing printer, might take about two minutes to print.

With the Starwriter, it might take closer to three.

The typical 45 cps printer retails for about$3,000.

But the Starwriter 25 retails for about $1,895—thus saving you about $1,000.

And therein lies the biggest difference between the Starwriter 25 and the more expensive, daisy wheel printers.

The Starwriter 25 comes complete and ready-to-use, requiring no changes in hardware or software. It uses industry-standard ribbon cartridges, and it's "plug-in" compatible to interface with a

wide variety of systems, to help lower system-integration costs.

Using a 96-character wheel, it produces excellent letter-quality printing on three sharp copies with up to 163 columns, and offers the most precise character-placement available, for outstanding print performance.

C. Itoh's warranty;

3 months on parts and labor, supported by one of the best service organizations in the industry.

'iOOOOFF

Leading Edge Products, Inc., 225 Turnpike Street, Canton, Massachusetts 02021

Dear Leading Edge:

I'd like to know more about the Starwriter, and how spendinga minute can save me a grand. Please send me the name of my nearest dealer.

Name_ Title_

Company.

Street .

State

_Zip_

Phone: Area Code. Number

LEADING EDGE.

Leading Edge Products, Inc., 225 Turnpike Street, Canton, Massachusetts 02021

Dealer inquiries invited. For immediate delivery from the Leading Edge Inventory Bank™ call toll free 1-800-343-6833

In Massachusetts, call collect (617)828-8150. Telex 951-624

BYTE March 1981

91

SuperSoft's

Gallery off CP/M Masierwbrks

£

DIAGNOSTICS I: A system diagnostic package. Tests:

• Memory • CPU (8080/8085/Z80) • Terminal • Disk • Printer To our knowledge the CPU test is the first ot its kind anywhere. Diagnostics I can help you find problems before they become serious. A good set of diagnostic routines are a must in any program library. Minimal requirements: 32K CP/M. Supplied with complete user manual: S75.00 Manual alone: $15.00

DIAGNOSTICS II: The most comprehensive set of CP/M compatible system check-out programs ever assembled. Includes all of Diagnostics I, plus:

• Every test is "submlt"-able

• A complete Splnwrlter/Diablo/Qume test has been added (Serial Interlace only)

• Output may be logged to disk

• Expanded memory test

• Expanded terminal test

• Expanded disk test

Diagnostics II provides the next level In system maintenance. Requires: 32K CP/M Price: $100.00 Manual only: $15.00

t Price: $

KS3E

SYSTEM MAINTENANCE

SUPER-M-LIST: A complete, easy to use mailing list program package. Allows for two names, two addresses, city, state, zip and a three digit code field for added flexibility. Super-M-List can sort on any field and produce mailing labels direct to printer or disk file for later printing or use by other programs. Super-M-List is the perfect companion toTFS. Handles 1981 Zip Codes! Requires: 48K CP/M Supplied with complete user manual: $75.00 manual alone: $10.00

TFS-Ttxl Formatting Syttam: An extremely powerful formatter. More than 50 commands. Supports all major features Including;

• left & right margin justification • user defined macros

• dynamic Insertion from disk file • underlining and backspace TFS lets you make multiple copies of any text. For example: Personalized form letters complete with name, address & other Insertions from a disk file. Text Is not limited to the size of RAM making TFS perfect for reports or any big Job. Text Is entered using CP/M standard editor or most any CP/M compatible editor. Requires: 24K CP/M

Supplied with extensive user manual: $85.00 manual alone: $20.00 Source to TFS In 8080 assembler (can be assembled using standard CP/M assembler) plus user manual: $250.00.

4

TEXT PROCESSING

I

UTILITIES I: A collection of programs that you will find useful and

maybe even necessary In your dally work (we did!).

Includes:

GREP: Searches files for a specilied string

SORT: In core sort of variable length records

CMP: Compare two flies for equality

PRINT: Formatted listings to printer

PG: Lists files to CRT a page at a time

.. . plus more . . , Requires: 24K CP/M Supplied with manual on discette: $60.00

UTILITIES II: Many new programs not available elsewhere. Includes these "file" utilities:

DIFF: Source comparltor

Powerful multlcolumn output formatter Desk calculator Substitute strings in files

.. . plus more . . . Requires: 24K CP/M $60.00 Supplied with manual on discette

UTILITIES

j353&

ANALIZA: An amazingly accurate simulation of a session with a psychiatrist. Better than the famous "ELIZA" program. Enlightening as well as fun. An excellent example of Artificial Intelligence. Requires: 48K CP/M, CBASIC2 Cost: $35.00

ENTERTAINMENT

m

Z8000CROSSASSEMBLER:Supports full ZB000 syntax, segmented and unsegmented mode, full 32-bit arithmetic, hex output, listing output, "downloader". Requires: 56K CP/M $50000 1 year maintenance $300.00 manual alone 5 5000

m\m

zeooo toot I

^J

On line "Help" system provided with every program package.

SuperSoft

First in Software Technology

CPIM REGISTERED TRADEMARK DIGITAL RESEARCH

ft * * * * * 4 * * x x x * * x x x ^ST-JT

SSS FORTRAN: The SSS FORTRAN compiler is fast, efficient, and complete (full 1966 ANSI standard with extensions). The RATFOR compiler compiles into FORTRAN allowing the user to write structured code while retaining the benefits of FORTRAN. The FORTRAN supports many advanced features not found in less complete implementations, including: complex arithmetic, character variables, and functions Complete sequencial and random disk I/O are supported. SSS FORTRAN will compile up to 600 lines per minute! Recursive subroutines with sialic variables are supported. ROMable "COM" files may be generated. SSS RATFOR allows the use of contemporary loop control and structured programming techniques. SSS RATFOR is similar to FORTRAN 77 in that it supports such things as:

• REPEAT...UNTIL • WHILE • IF...THEN...ELSE SSS RATFOR is supplied with source code in FORTRAN and RATFOR. System Requirements & Prices:

SSS FORTRAN requires a 32K CP/M system.

SSS FORTRAN with RATFOR: $325.00

SS FORTRAN alone: $250.00

RATFOR alone: $100.00

(RATFOR sold only with valid SSS FORTRAN license)

STACKWORK'S FORTH: A lull, extended Forth interpreter/compiler produces COMPACT, ROMABLE code. As fast as compiled FORTRAN, as easy to use as interactive BASIC. SELF COMPILING; Includes every line of source code necessary to recompile

itself. EXTENSIBLE: Add functions at will. Z80 or 8080 ASSEMBLER Included. Single license, OEM licensing available. Please specify CPU type: Z60 or 8080 Supplied with extensive user manual and tutorial: $175.00 Documentation alone: $25.00

'TINY' PASCAL II: We still call it 'Tiny' but it's bigger and better than ever! This is the famousChung-Yuen 'Tiny' Pascal with more features added. Features include:

• recursive procedures/functions • integer arithmetic • CASE

• FOR (loop) " sequential disk I/O " 1 dimensional arrays

• IF..THEN...ELSE • WHILE • PEAK & POKE

• READS, WRITE • REPEAT...UNTIL • more

'Tiny' Pascal is fast. Programs execute up to ten times faster than similar BASIC programs. SOURCE TOO! We still distribute source, In 'Tiny' Pascal, on each discette sold. You can even recompile the compiler, add features or Just gain insight Into compiler construction.

Requires; 36K CP/M. Supplied with complete user manual and source on discette: $85.00. Manual alone: $10.00

ag '♦"♦"♦"»"<

PROGRAMMING LANGUAGES

BgggggB

TERM: A complete intercommunications package for linking your computer to other computers. Link either to other CP/M computers or to large timesharing systems. TERM is comparable to other systems but costs less, delivers more and source is provided on discette! With TERM you can send and receive ASCII and Hex files (COM too, with included convertion program) with any other real time communication between users on separate systems as well as acting as timesharing terminal.

• Engage/disengage printer • errorcheckingandauto retry

• terminal mode for timesharing between systems

• conversational mode • send files ■ receive files Requires; 32K CP/M

Supplied with user manual and 8080 source code: $150.00 Manual alone: $15.00

^INTERCOMPUTER COMMUNICATIONS*

ENCODE/DECODE: A complete software security system for CP/M. Encode/Decode Is a sophisticated coding program package which transforms data stored on disk into coded text which is completely unrecognizable. Encode/Decode supports multiple security levels and passwords. A user defined combination (One billion possible) is used to code and decode a file. Uses are unlimited. Below are a few examples:

• data bases • payroll files ■ programs ■ tax records

Encode/Decode is available in two versions:

Encode/Decode I provides a level of security suitable for normal use Encode/Decode II provides enhanced security for the most demanding needs. Encode/Decode I: $50.00 Encode/Decode II: $100.00 manual alone: $15.00

SOFTWARE SECURITY

F=

CP/M Formats: 8" soft sectored, 5" Northstar, 5" Micropolis Mod II, Vector MZ, Superbrain DD/QD All Orders and General Information: SUPERSOFT ASSOCIATES P.O. BOX 1628 CHAMPAIGN, IL 61820 (217) 359-2112

Technical Hot Line: (217) 359-2691 (answered only when technician Is available)

Far East Distribution:

ASR International

3-15-8. NlSHI-SHIMBASHI. MINATO-KU, TOKYO j 105 JAPAN

(031437-5471

SwperSofft's Masterpiece of the Month

,0 to

SSS ANSI *ee STANDARD

rCCTCAN IV

WITH

EArrcc

o,~

P€R CP/M

TOGETHER AT LAST

SSS FORTRAN & RATFOR are the critic's choice!

The SSS FORTRAN compiler is fast, efficient, and complete (full 1966 ANSI standard with extensions). The RATFOR compiler compiles into FORTRAN allowing the user to write structured code while retaining the benefits of FORTRAN, Together they form an incredible team!

SSS FORTRAN Specifics SSS FORTRAN makes full FORTRAN IV available to microcomputers. SSS FORTRAN meets and exceeds the ANS11966 FORTRAN standard. The compiler supports many advanced features not found in less complete implementations, including: complex arithmetic, character variables, and functions. SSS FORTRAN will compile up to 600 lines per minute! Recursive subroutines with static variables are supported. ROMable ".COM" files may be generated.

FEATURES

Code generation: ROMable ".COM" files or intermediate code files (saves disk space). External routines may be called.

Data types: Byte, integer, real, double precision, complex, logical, charac

ter and varying length strings.

Operations: All standard operations plus string comparisons, assignments,

and .XOR.

Constants: Hexadecimal, decimal, and character literals with features to

imbed control characters.

Statements: ANSI 1966 standard with multiple statement lines, state

ments may end with a':'.

Controls: Map. List, and Symbol table output options.

I/O: Read, Write, Append, Rewind, Close, Delete. Rename, Search,

sequencial and Random I/O on disk files. Supports all CP/M devices. The User can add device handlers to use custom I/O devices.

Errors: Over 200 distinct compiler error messages, precision and

illegal instruction warnings during execution.

Interrupts: FORTRAN programs may be interrupted at any time; the stack

pointer is always preserved.

• • PEAXUCING m •

SSS RATFOR RATFOR is a preprocessor that compiles to SSS FORTRAN. SSS RATFOR allows the use of contemporary loop control and structured programing techinques. SSS RATFOR is similar to FORTRAN 77 in that it supports such things as: REPEAT ... UNTIL WHILE IF .. .THEN ... ELSE

Begin End Brackets Macro Defines

SSS RATFOR is supplied with source code. The source code is distributed in both RATFOR and SSS FORTRAN. Not only does this prevent obsolescence, but allows the user to add enhancements as desired.

• •••••••••••

System Requirements & Prices

SSS FORTRAN requires a 32k CP/M system. Z80 only. SSS FORTRAN with RATFOR: $325.00 SSS FORTRAN alone: $250.00

RATFOR alone: $100.00

(Sold only with valid SSS FORTRAN license)

CP/M Formats: 8" soft sectored, 5" Morthstar. 5" Micropolis Mod II. Vector MZ. Superbrain DD/OD

All Orders and General Information:

SUPERSOFT ASSOCIATES

P.O. BOX 1628

CHAMPAIGN, IL 61820

(217)359-2112

Technical Hot Line: (217) 359-2691

(answered only when technician is available)

•CP/M REGISTERED TRADEMARK DIGITAL RESEARCH

SSS FORTRAN is the copyright ot Small Systems Services. Urbana. Illinois

SuperSoft

First in Software Technology

BYTE March 1981

93

Figure 1: Block diagram of the Radio Shack Color Computer. Although a detailed schematic diagram is not available, the connection of the main components can be readily determined. Note that the use of large-scale integrated circuits (the microprocessor, SAM dynamic-memory handler, video-display generator, and parallel port interfaces) means that a minimum number of components is necessary to build this flexible computer.

94 March 1981 © BYTE Publications Inc

Circle 50 on Inquiry card.

NOW CLEANING YOUR OWN

DISKETTE HEADS COULD SAVE

YOU A$40 SERVICE CALL.

AND A LOT MORE.

The recording heads on your diske e drives may be dirty— and that can cause you a lot of grief. There's the serviceman you have to call when the machine doesn't perform. (You know how much service calls cost these days!) There's machine down-time. Idle data entry clerks. All the other delays a cranky machine can cause. And that service call might not even be necessary.

3M solves the problem in seconds—and leaves

your heads "Computer Room Clean".

The Scotch® head-cleaning diskette kit lets you clean the read-write heads on your 8" or 51/4" diskette drives. \n just 30 seconds, without any disassembly, mess or bother, the heads can be completely cleansed of dirt, dust, magnetic oxides-all the things that can get into your machines ©very day. And foul them up.

Just saturate the special white cleaning pad in its jacket with the cleaning solution. Then insert the jacket into the diskette drive and turn it on. Your machine does the rest. The

heads are microscopically cleaned without wear, without abrasion.

This 3M head-cleaning diskette kit has been evaluated and approved by major diskette drive manufacturers. It's the best possible way to clean your heads without service calls or machine teardowns.

At only $1 per cleaningit's the best insurance you can get.

This fast-cleaning new Scotch kit comes with everything you need (including special fluid, applicatortip, cleaning diskettes) to handle up to 30 cleanings. That's only about a dollar a cleaning.

With the Scotch head-cleaning diskette kit, you could save yourself a lot more than just a service call. So try this remarkable kit today. For the name of

A Scotch cleaning diskette shown before use. and after 75 cleanings of recording heads.

the dealer nearest you, call toll

free: 800-328-1300.

(In Minnesota, call collect:

612-736-9625.) Ask for the

Data Recording Products

Division.

(Not yet available tor Burroughs Mini-Disk II, Vydec or 96 TPI Drive)

vssC

1

40

] HALT

NMI [

2

39

]TSC

Frq [

3

38

] LIC

fTrq Q"

4

37

J RESET

BS [

5

36

] AVMA

BA [

6

35

]Q

vccC

7

34

]E

AO [

8

33

]BUSY

Al[

9

32

]r/w

A2[

10

31

]oo

A3[

11

30

]D1

A 4 [

12

29

]02

»U

13

28

]D3

A6 [

14

27

]D4

A7[

15

26

]05

A8[

16

25

]06

A9 [

17

24

]07

AlO [

18

23

]A15

All [

19

22

1A14

A12 [

20

21

]A13

Figure 2: Pin description of Motorola's MC6809E microprocessor. The device has several 16-bit instructions that, coupled with ease of programming and speed, make for a very powerful 8-bit processor.

15

0

X-INDEX REGISTER

Y-INDEX REGISTER

U-USER STACK POINTER

S-HARDWARE STACK POINTER

PC

A

B

V

'

POINTER REGISTERS

PROGRAM COUNTER ACCUMULATORS

Text continued from page 90:

BASICs now available. It has two 16-bit index registers and two 16-bit stack pointers, as well as two 8-bit accumulators that can be used as a double-precision 16-bit accumulator. It supports both positionindependent code (code that can be executed anywhere in memory without reassembly) and reentrant (interruptible) code.

The video display is generated by the Motorola MC6847 VDG (video display generator). This is a 40-pin LSI (large-scale integration) part that reads from Vi K bytes to 6 K bytes of memory, depending on mode, to produce an analog video signal. This signal is fed to the MC1372 color-subcarrier modulator to get composite video, which is then modulated by the ASTEC video modulator to channel 3 or 4.

The Color BASIC interpreter is stored in an 8 K by 8 bit ROM (read-only memory). Its companion, Extended BASIC, comes in another ROM of the same type. The basic machine comes with only the first ROM; the extended ROM costs $99 plus installation.

As mentioned, the computer comes with eight MCM4027 4 K-bit dynamic memory circuits. Tandy will upgrade your system to 16 K bytes by replacing these with MCM4116s (16 K-bit devices) for $119. Or you can buy the system with 16 K bytes and the Extended BASIC ROM for $599.

These memory circuits are controlled and refreshed by a special part, the MC6883 SAM (synchronous address multiplexer). It provides all the signals for the memory and the VDG and also provides the timing signals for the microprocessor.

The other I/O functions are all handled by parallel ports in the form of MC6821 PIAs (peripheral interface adapters). The keyboard is connected to these and is scanned and decoded in software. The serial port and cassette port are both derived from a single parallel line and are selected by software. The optional joysticks are encoded with an A/D (analog-to-digital) converter composed of a resistive-summing network hooked to a 6-bit parallel port and an LM339 comparator.

DP

DIRECT PAGE REGISTER

CC-CONDITION CODE REGISTER

CARRY

OVERFLOW

ZERO

NEGATIVE

IRQ MASK

HALF CARRY

FIRQ MASK

ENTIRE FLAG

Figure 3: Registers available in the 6809. Similar in architecture to the 6800, the 6809 has three extra registers to facilitate memory acesses: a direct page register, a user stack register, and a second index register. The instruction set is also more robust, with the addition of 16-bit add, subtract, and multiply operations.

The MC6809E Microprocessor

The third-generation MC6809E 8-bit microprocessor features several 16-bit operations. This puts it functionally between the 8- and the 16-bit processors. A description of the MC6809E signals appears in figure 2.

The programming model of the MC6809E is shown in figure 3. Three registers were added to the register set of the original MC6800:

•a direct page register •a user stack pointer •a second index register

There are two 8-bit accumulator registers, the A register and the B register, that are used for data manipulation and serve as holding registers for arithmetic calculations. The MC6809E has many 16-bit arithmetic operations, including additions, subtractions, loads, stores, and an 8 bit by 8 bit multiplication. The 16-bit arithmetic operations use both accumulators —with the A register treated

96 March 1981 © BYTE Publications Inc

Circle 51 on Inquiry card.

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Efficient position-independent code

can be written using the

capabilities of the MC6809E.

as the most significant byte. When the A and B registers are concatenated, they are referred to as the D register.

The DP (direct page) register is one of the new registers. Its contents form the high-order byte of the address bus during instructions utilizing the direct addressing mode. This register may be changed to allow direct addressing anywhere in the 64 K-byte memory map, as compared to the MC6800, which allowed direct addressing only in the first 256 bytes of the memory map. Direct addressing uses the immediate byte of the instruction as a 1-byte pointer into a single 256-byte "page" of memory. This shortens instruction execution time because the high-order byte is furnished by the direct page register. MC6800 source code compatibility is ensured because actuation of the RESET line clears the direct page register.

The MC6809E has four 16-bit pointer registers available to the user. The U and S registers support stackoriented instructions such as PSH and PUL. The S register is used as the hardware stack pointer to support interrupts and subroutine calls. The U register gives the designer the capability of maintaining an independent stack.

The other two registers, X and Y, are intended primarily for use as index registers, although special indexing

modes allow them to be used to maintain additional stack areas. All four pointer registers can be used as index registers, allowing indexed addressing, indirect addressing, or indexed indirect addressing. These pointer register capabilities permit the MC6809E to function efficiently as a stack processor, allowing the microprocessor to support graphics, high-level languages, and modular programming techniques.

The microprocessor's program counter, while primarily used by the processor to address the next instruction, may be referenced as an index register, thus allowing addressing relative to the program counter.

The condition code register defines the state of the microprocessor such that conditional branch instructions may be used. The condition code register also allows masking of some of the interrupts.

The register set is manipulated with the 59 instructions shown in table 2. Over 1460 different op codes are available to the programmer if all modes of the instructions are considered. However, only the 59 mnemonics must be remembered when using an assembler.

Efficient PIC (position-independent code) can be written using the capabilities of the MC6809E. The program counter can be used as a pointer to provide offsets within the program. For example, when a portion of PIC is executed, the stack addresses, peripheral addresses, and other addresses may be specified as offsets from the current program counter address.

Other key factors in effective position-independent code writing are the use of long and short relative-branch

Text continued on page 102

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98 March 1961 © BYTE Publications Inc

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Whitesmiths Ltd. offers a variety of licensing arrangements, the simplest being a binary license for use on a single CPU. The full source code is available with internal documentation. Maintenance, training and sublicensing rights may also be obtained.

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Source

Operating

Systems

8080/Z80 CP/M

LSI-11/PDP-11: Idris, Unix, RT11, RSX-ll/M, RSTS/E, IAS

VAX-11

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VMS

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Target Machines

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C: $630 Pascal: $880

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C: $630 Pascal: $880

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C: $1130 Pascal: $1380

C: $1130 Pascal: $1380

C:$630 Pascal: $880

Idris is a trademark of Whitesmiths, Lid I Unix is a trademark of Bell Laboratories I CP/M is a trad cm ark of Digital Research Company ■ VMS, RSX-ll/M, RSTS/E, LSI-11, VAX, are trademnrks of Digital Equipment Corporation I VERSAdos is a trademark of Motorola Corporation

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Circle 75 on inquiry card.

BYTE March 1981 99

Circle 53 on inquiry card. /

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8-BIT OPERATIONS

Mnemonic

Description

ABX

Add B register to X register unsigned.

ADCA, ADCB

Add memory to accumulator with carry.

ADDA, ADDB

Add memory to accumulator.

ANDA, ANDB

AND memory with accumulator.

ANDCC

AND immediate with condition code register.

ASLA, ASLB, ASL

Arithmetic shift left accumulator or memory.

ASRA, ASRB, ARS

Arithmetic shift right accumulator or memory.

BITA, BITB

Bit test memory with accumulator.

CLRA, CLRB, clr

Clear accumulator or memory.

CMPA, CMPB

Compare memory with accumulator.

COMA, COMB, COM

Complement accumulator or memory.

DAA

Decimal Adjust A accumulator.

DECA, DECB, DEC

Decrement accumulator or memory.

EORA, EORB

Exclusive OR memory with accumulator.

EXG R1, R2

Exchange R1 and R2.

INCA, INCB, INC

Increment accumulator or memory.

LDA, LDB

Load accumulator from memory.

LSLA, LSLB, lsl

Logical shift left accumulator or memory.

LSRA, LSRB, LSR

Logical shift right accumulator or memory.

MUL

Unsigned multiply (8 bit by 8 bit = 16 bit).

NEGA, NEGB, NEG

Negate accumulator or memory.

ORA, ORB

OR memory with accumulator.

ORCC

OR immediate with condition code register.

PSHS (register list)

Push register(s) on hardware stack.

PSHU (register list)

Push register(s) on user stack.

PULS (register list)

Pull register(s) from hardware stack.

PULU (register list)

Pull register(s) from user stack.

ROLA, ROLB, ROL

Rotate accumulator or memory left.

RORA, RORB, ROR

Rotate accumulator or memory right.

SBCA, SBCB

Subtract memory from accumulator with borrow.

STA, STB

Store accumulator to memory.

SUBA, SUBB

Subtract memory from accumulator.

TSTA, TSTB, TST

Test accumulator or memory.

TFR R1, R2

Transfer register R1 to register R2.

16-BIT OPERATIONS

Mnemonic

Description

ADDD

Add to D accumulator.

SUBD

Subtract from D accumulator.

LDD

Load D accumulator.

STD

Store D accumulator.

CMPD

Compare D accumulator.

LDX, LDY, LDX, LDU

Load pointer register.

STX, STY, STS, STU

Store printer register.

CMPX, CMPY, CMPU,

CM PS

Compare pointer register.

LEAX, LEAY, LEAS,

LEAU

Load effective address into pointer register.

SEX

Sign extend

TFR register, register

Transfer register to register.

EXG register, register

Exchange register to register.

PSHS (register list)

Push register(s) onto hardware stack.

PSHU (register list)

Push register(s) onto user stack.

PULS (register list)

Pull register(s) from hardware stack.

PULU (register list)

Pull register(s) from user stack.

Table 2: The 6809 instruction set.

100

March 1981 © BYTE Publications Inc

Circle 54 on inquiry card.

INDEXED ADDRESSING MODES

Mnemonic

Description

0, R

Indexed with zero offset.

[0, R]

Indexed with zero offset indirect.

,R +

Autoincrement by 1.

,R+ +

Autoincrement by 2.

l,R++]

Autoincrement by 2 indirect.

,-R

Autodecrement by 1.

, R

Aufodecrement by 2.

[,--R]

Autodecrement by 2 indirect.

n, P

Indexed with signed n as offset (n = 5, 8, or 16 bits).

[n. P]

Indexed with signed n as offset indirect.

A, R

Indexed with accumulator A as offset.

[A, R]

Indexed with accumulator A as offset indirect.

B, R

Indexed with accumulator B as offset.

[B, R]

Indexed with accumulator B as offset indirect.

D, R

Indexed with accumulator D as offset.

[D, R]

Indexed with accumulator D as offset indirect.

NOTE: Ft =

X, Y, U, or S; P = PC, X, Y, U, or S. Brackets indicate indirection. D

means use AB accumulator pair.

6809 RELATIVE SHORT AND LONG BRANCHES

Mnemonic

Description

BCC, LBCC

Branch if carry clear.

BCS, LBCS

Branch if carry set.

BEQ, LBEQ

Branch if equal.

BGE, LBGE

Branch if greater than or equal (signed).

BGT, LBGT

Branch if greater (signed).

BHI, LBHI

Branch if higher (unsigned).

BHS, LBHS

Branch if higher or same (unsigned).

BLE, LBLE

Branch if less than or equal (signed).

BLO, LBLO

Branch if lower (unsigned).

BLS, LBLS

Branch if lower or same (unsigned).

BLT, LBLT

Branch if less than (signed).

BMI, LBMI

Branch if minus.

BNE, LBNE

Branch if not equal.

BPL, LBPL

Branch if plus.

BRA, LBRA

Branch always.

BRN, LBRN

Branch never.

BSR, LBSR

Branch to subroutine.

BVC, LBVC

Branch if overflow clear.

BVS, LBVS

Branch if overflow set.

6809 MISCELLANEOUS INSTRUCTIONS

Mnemonic

Description

CWAI

Clear condition code register bits and wait for interrupt.

NOP

No operation.

JMP

Jump.

JSR

Jump to subroutine.

RTI

Return from interrupt.

RTS

Return from subroutine.

SEX

Sign extend B register into A register.

SWI, SWI2,

SWI3 Software interrupts.

SYNC

Synchronize with interrupt line.

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Text continued from page 98:

instructions and LEA (load effective address) instructions. The relative-branch instructions allow PCR (program counter relative) branching. When an 8-bit offset is used, control may be transferred anywhere within a 256-byte area. A 16-bit offset allows transfer of control anywhere in the entire 64 K-byte address space. The following are examples of the relative-branch instructions:

DECA Decrement A Accumulator

BEQ CAT If A = 0 then go to CAT

(CAT is within ± 128 bytes)

INCA Increment A Accumulator

LBEQ DOG If A = 0 then go to DOG

(DOG is within ± 32,768 bytes)

The LEA instructions work by calculating the effective address of an indexed instruction and storing it in the specified pointer register. This allows the programmer to use all the internal addressing hardware of the microprocessor. Below are some examples of the LEA instructions.

Instruction LEAX 10,X LEAY A,Y LEAX D,Y LEAU -10,U LEAX TABLE,PCR

Operation X + 10 - X

Y + A - Y

Y + D - X U - 10 - U (see text below)

102 March 1981 © BYTE Publications Inc

Note how the registers may be incremented or decremented using the LEA instructions. In addition, registers may be used as offsets, as explained above. The program counter may be used as a pointer register with 8- or 16-bit signed offsets. As in relative addressing, the offset is added to the current contents of the program counter register to create the effective address.

The last example calculates the offset of TABLE and adds it to the current value of the program counter register. This value is then placed in the X register. Tables related to a particular routine will maintain the same relationship after the routine is moved, since addresses are calculated when the code is executed.

Position-independent code is not without disadvantages, the major being that it generally takes 5 to 10 percent more space than nonrelocatable code. In addition, PIC usually takes 5 to 10 percent more time to execute. Typically, PIC would be used for utility programs where the run-time addresses are dynamically determined. This eliminates the need for a linking loader to perform a relocation operation. Common examples of this type of code would be machine-language utilities such as graphic routines and subroutines called by BASIC programs.

The MC6809E has several very interesting hardware features also. Referring to the signal descriptions of figure 2, note that not only does the microprocessor have 16 address lines, 8 data lines, and an R/W (read/write) line, but there are several other control lines. The MC6809E is synchronized to the video-display circuit by the two clock inputs, E and Q. These two clocks control internal operation of the microprocessor. Figure 4 shows typical timing diagrams for bus operations.

Circle 56 on inquiry card. >

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INTEGRATION. The original AR and AP systems had to be changed and recompiled to feed journal entries to GL. Our installation program eliminates this hassle. It simply asks you if you want the systems integrated, and what your special account numbers are.

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Three interrupt control lines, NMI, FIRQ, and IRQ, allow peripherals to request (demand!) support. Each interrupt causes the microprocessor to retrieve a vector from a specific address and use it to begin executing instructions.

The Color Computer uses IRQ (interrupt request) and FIRQ (fast interrupt request) to support real-time clock input (driven by the horizontal and vertical sync signal from the VDG) and to auto-start read-only memory cartridges. The NMI (nonmaskable interrupt) input is reserved for use by the expansion port.

These interrupts function in different manners. The NMI cannot be disabled or postponed under software control and is useful in real-time interrupt-servicing disk transfers. The other two interrupts are maskable under software control. One is "faster" than the other in that a response to an FIRQ saves only the condition code register and the program counter on the stack. The other, IRQ, "stacks" all the registers, as does NMI. Separate interrupts were used for the PIAs (parallel interface adapters) to provide independent vector addresses for the service routines, thereby minimizing the software overhead.

The interrupt vectors in the Color Computer are mapped to the top of the BASIC ROM by the SAM chip. These vectors point to locations in programmable memory starting at address hexadecimal 100. On reset, the BASIC program stores jump instructions in these locations which point to the interrupt-service routines. Each jump call consists of 3 bytes: the jump extended op code (hexadecimal 7E) and the address of the routine. If a particular interrupt is not being used, all 3 bytes of its jump call would contain 00. See table 3 for a map of the interrupt-service addresses.

To define a jump call, program the 3 bytes with the required jump instruction. For example, if the SWI (software interrupt) service routine is located at hexadecimal 8000, the SWI jump call should be loaded with 7E 80 00. The following BASIC program would load the SWI jump call with this vector:

POKE 264,0 POKE 263,128 POKE 262,126

This example program defines the last byte of the jump call first, then the middle byte, then the first byte. This approach is required to prevent interrupt service until the jump call is completely defined. If the jump call was defined by starting with the first byte, an interrupt could be vectored to the wrong address. All interrupt-service routines should end with a hexadecimal 3B (Return from Interrupt op code) to restore the Color Computer to the proper state.

Two other MC6809E input-control signals used by the Color Computer are HALT and RESET. RESET is controlled by the pushbutton switch on the rear right-hand portion of the Color Computer. When the switch is pressed, RESET goes low to initiate a restart routine. The HALT input is connected to the expansion port. When HALT goes low, the MC6809E completes the current instruction, then releases the address, data, and R/W lines to the high-impedance state. This allows another device,

Text continued on page 110

104 March 1981 © BYTE Publications Inc

Circle 87 on inquiry card.

Circle 57 on inquiry card.

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5?

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Figure 4: Timing diagrams for 6809 bus operations. As with the 6800, both memory and peripherals are accessed in the same way and share the same address space. The complete instruction cycle.for reads (figure 4a) and writes (figure 4b) is the same: approximately 1.1 us.

106 March 1981 © BYTE Publications Inc

Circle 27 on inquiry card.

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Circle 59 on inquiry card.

Contents of

Address of

Indirect

Indirect

Interrupt

Routine

Routine

Interrupt

Vector Call Address

Call

Source

(hexadecimal) (hexadecimal) (hexadecimal)

Reset

FFFE

A027

none

direct call to restart

NMI

FFFC

0109

undefined

not used

SWI

FFFA

0106

undefined

not used

IRQ

FFF8

010C

A9B3

Extended

BASIC

uses

894C to

update

real-time

clock.

FIRQ

FFF6

010F

A0F6

SWI2

FFF4

0103

undefined

not used

SWI3

FFF2

0100

undefined

not used

Table 3:

Interrupt vectors for Color

Computer BASIC. At

the reception of an interrupt, control

is transferred to a ser

vice routine via a call to an address stored near the

top of the

64 K address space (occupied by th

e BASIC ROM). The

address points to a 3-byte

jump instruction (loaded into pro

grammable memory when BASIC is initialized); that, in

turn, po

nts to an interrupt-handling

routine.

Bus Available Signal

Bus Status Signal

Machine State

low low high high

low high low high

Normal (running) Synchronize Acknowledge Interrupt Acknowledge Halt/Bus-Grant Acknowledge

Table 4: The four possible machine states. The Bus Available and Bus Status signals can be decoded to detect when the bus is not being used by the processor.

Text continued from page 104:

such as a DMA (direct-memory access) controller, to control the bus.

Since the microprocessor is not halted until completion of the current instruction, the external bus controller has to wait 20 bus cycles before driving the bus. This delay is required because the longest execution time for an MC6809E instruction is 20 cycles for a CWAI instruction (see table 2).

This delay could have been minimized if the BA and BS lines were brought out to the expansion port. BA and BS (Bus Available and Bus Status) indicate one of four machine states. These four states and the BA and BS signal combinations are shown in table 4.

Of the four states, the Halt/Bus-Grant Acknowledge is the only one pertinent to the design of the Color Computer. The Normal state indicates that the microprocessor is executing code. The Synchronize Acknowledge state, which allows the processor to be synchronized to an external event, is not required in the Color Computer. Nor is the Interrupt Acknowledge state, which indicates that vector fetches are occurring.

Four other MC6809E signals were ignored by the Color Computer's designers: TSC, AVMA, BUSY, and LIC. TSC (Three State Control) is used to put the buses into the high-impedance state for cycle-stealing operations.

1

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4

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20

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Figure 5: Pin description of Motorola's MC6847 Video Display Generator. In concert with the Synchronous Address Multiplexer (see figure 6), this device interprets the contents of a block of memory to create a color display (using either an internal character generator or an external one). The output signal is converted to composite video by an MC1372, while a device built of discrete components modulates the signal to radio frequencies for reception on a standard television.

This type of operation is typically used for DMA or dynamic-memory refresh and is not needed in the Color Computer.

AVMA, BUSY, and LIC are intended primarily for use in multiprocessor systems (which the Color Computer is not). AVMA (Advanced Valid Memory Access) is the signal indication that the processor will use the bus during the next cycle. The BUSY output provides the "indivisible" memory indication required for a "test and set" operation (operations of this type are required for efficient multiprocessor support on a common bus). LIC (Last Instruction Cycle) indicates that the first byte of an op code will be latched at the end of the present bus cycle.

The MC6809E was the best choice of the microprocessors available for use when the Color Computer was designed. The external clock inputs allow the microprocessor to be synchronized to the video display to allow interleaved memory accesses. In addition, the power of the MC6809E instruction set allows the efficient graphics drivers supported by the Extended BASIC.

The Video Display and the Memory Controller

The "Color" in Color Computer comes from the MC6847 Video Display Generator. This device can display information stored in memory using a variety of alphanumeric, semigraphic, and graphic modes. To understand how it works, refer to the signal description shown in figure 5. Normally the address lines DA0 thru DA12 would be connected to a block of programmable memory (usually static devices such as MCM2114s) shared with the microprocessor. Depending on the mode selected, the VDG would read the memory and, taking

110 March 1981 © BYTE Publications Inc

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Circle 60 on inquiry card.

BYTE March 1981

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the information off its data lines (DD0 thru DD7), it would format and shift out video information to its companion part (the MC1372 Color Television Modulator) to be transmitted to a TV receiver.

This method of using the part is fine, but it has a few drawbacks. First, there needs to be a way to allow the microprocessor to write its output data to memory. This means that there must be three-state buffers between the microprocessor bus and the VDG bus (and logic to control them). A control pin on the VDG, Memory Select (MS), must be used to put the VDG's address lines in the high-impedance state when the processor accesses the memory.

One side effect of this is that the VDG shift registers will be filled with the data from its data bus as usual, except that the address lines are under the control of the microprocessor, and so the data that gets sent out on the video lines is incorrect. This results in "sparkles" of random color on the TV screen and can be annoying when you are trying to move your TIE fighter out of enemy gunsights!

Second, there is only one block of memory for the VDG to "look" at. In trying to implement computer animation, it would be nice to allow the microprocessor to draw one picture while another is being displayed. Then you would simply swap memory pages and, voila, the horse moves! You can't do this with the system outlined above unless you resort to fancy hardware.

Of course, both of these problems can be overcome. We have seen it done with an entire board full of TTL (transistor-transistor logic) packages but this is expensive and not for the faint of heart. Fortunately, these problems have a solution in the form of another LSI device from—you guessed it—Motorola. The MC6883 SAM (Synchronous Address Multiplexer) is a 40-pin TTL part that marries the MC6809E and the MC6847 to some dynamic programmable memory.

SAM, the Synchronous Address Multiplexer

The little jewel called the SAM should really interest computer experimenters. In the first place, it provides the clock signals needed by the microprocessor. The E and Q clocks are derived from the 14.31818 MHz crystal —they are normally 895 kHz —but this can be changed, as we will see. Secondly, the SAM also provides RAS (rowaddress strobe) and CAS (column-address strobe) signals for dynamic-memory refresh. As anyone who has tried to design a dynamic-memory board can tell you, it isn't easy; and one of the hardest things is deriving RAS and CAS and hiding the refresh cycle from the processor. The SAM does it all and could do it even without a VDG. A complete memory board could be designed around this device even if you didn't want a video display. A signal description of the MC6883 is given in figure 6.

To conserve the number of pins on a dynamic-memory circuit the address is multiplexed in 6-bit pieces (7 bits for 16 K-bit devices). The SAM takes all the microprocessor address lines, multiplexes them to the memory, and controls RAS, CAS, and WE (Write Enable). A typical read cycle is shown in figure 7.

The microprocessor puts out an address to read a location in the dynamic memory. The SAM splits this address into the row address and the column address. First the row address is presented to the memory on the output

112 March 1981 © BYTE Publications lnc

Circle 61 on inquiry card.

Circle 62 on inquiry card.

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Compare Morrow Designs' DISCUS" M26m hard disk systems to any system available for S-100 or Cromemco machines. First, compare features. Then, compare cost per megabyte. The M26 works out to under $200 a megabyte. And the M10 is about half the cost of competing systems.

COMPLETE SUBSYSTEMS.

Both the M10 (8"), and the M26 (14"), are delivered complete with disk controller, cables, fan, powersupply, cabinet and CP/M® operating system. It's your choice: 10 Mb 8" at $3,695 or 26 Mb 14"at $4,995. That's single unit. Quantity prices are available.

BUILDTO FOUR DRIVES.

104 Megabytes with the M26. 40+ megabytes with the M10. Formatted. Additional drives: M26: $4,495. M10: $3,195. Quantity discounts available.

S-100, CROMEMCO AND NORTH STAR*

The M26 and M10 are sealed-media hard disk drives. Both S-100 controllers incorporate intelligence to supervise all data transfers through four I/O ports (command, 2 status and data). Transfers between drives and controllers are transparent to the CPU. The controller can also generate interrupts at the completion of each command ... materially increasing system throughput. Sectors are individually write-protectable for multiuse environments. North Star or Cromemco? Call Micro Mike's, Amarillo, TX, (806) 372-3633 for the software package that allows the M26and M10to run on North Star DOS. MICAH of

■■: ■■ - .

Morrow Designs' 26 megabyte hard disk system: $4,995.

Sausalito, CA, (415)332-4443, offers a CP/M expanded to full Cromemco CDOS compatibility.

AND NOW, MULT-I/O.™

Mult-I/O is an I/O controller that allows multi-terminal and multi-purpose use of S-100 and Cromemcocomputers. Three serial and two parallel output ports. Real time clock. Fully programmable interrupt controller. Designed with daisy-wheel printers in mind. Price: $299 (kit), $349 assembled and tested.

MAKE HARD COMPARISONS.

You'll find that Morrow Designs' hard disk systems offer the best price/ performance ratios available for S-100, Cromemco and North Star computers. See the M26 and M10 hard disk subsystems at your computer dealer. Or, write Morrow Designs. Need information fast? Call us at (415) 524-2101.

Look to Morrow for answers.

MORROW OESIGN5

•CP/M is a trademark of Digital Research Corp. 'Cromemco is a trademark of Cromemco. Inc. "North Star is a trademark of North Star Computers. Inc.

5221 Central Avenue Richmond, CA 94804

\

/

\

/

\

D0-D7

I

VALID DATA

I

MEMORY A0-A7

V INVALID Y

ROW ADDRESS

X

COLUMN ADDRESS

CAS

V

J

RAS

V

/

WE

/

Figure 7: Typical read cycle of 4116-type dynamic memory circuits. To reduce the number of pins required, the memory device interprets the address being accessed as two sets of 7 bits that come at different times over the same set of pins. The memory cells of each device are arranged in an array, and the two sets of bits define a row address and a column address. When a set of address bits is valid, either the CAS (column-address strobe) or the RAS (row-address strobe) signal is sent to latch in the respective portion of the address.

lines ZO thru Z5, and the falling edge of RAS causes the memory to latch this part of the address into internal decoders. The SAM then puts out the column address and drops CAS. This causes the memory device to latch the column address and decodes the location in the internal memory array. The memory's stored data is then put on the data-output lines and through a buffer to the microprocessor.

Now, what about refreshing? Dynamic-memory circuits are made of small capacitor cells and, unless they are refreshed, the charge that represents the stored information will bleed off in a very short time. The memories are constructed such that merely accessing all the row addresses every 2 ms will keep the data alive. Usually this is done with counters that need only count from 0 to 63 (0 to 127 for 16 K-bit devices). The trick is to hide this from the microprocessor.

In the MC6809E, this is possible because the microprocessor needs to access memory only during the time that the E clock is high, so all that must be done is to refresh the memories when E is low. The SAM also does this little chore.

There are two differences between a system that uses 4 K-bit circuits and one that uses 16 K-bit devices. First, the MCM4116 integrated circuits have an extra address line which must be connected to the Z6 output of the SAM. Second, the refresh counters in the SAM must be programmed to put out 128 refresh addresses for the MCM4116s instead of the 64 needed for the MCM4027s.

The SAM has to be programmed to do this. How this is done will be detailed later.

In the Color Computer, the change is simple. There are only two jumpers that need to be switched to select either 4 K-bit or 16 K-bit memory devices. One of these connects the seventh address line, and one is connected to a PIA input line. Upon reset, the BASIC interpreter reads this bit and sets up the SAM for the type of memory indicated. That's all there is to it.

So what does all this have to do with the VDG? Since the VDG needs to be able to read memory to refresh the video screen, the SAM takes care of this, also. The address lines of the VDG are not connected at all in this system. Rather, the SAM is programmed into the same mode as the VDG and duplicates the timing of the VDG's address bus, except that it accesses memory to refresh the VDG during the E low time (so that the VDG accesses are transparent to the microprocessor). Since there is no possibility of a bus fight between the processor and the VDG, there is no need to deny the VDG access to the memory and the screen remains glitchless.

The full timing is shown in figure 8. The SAM usually provides memories with the address needed to access the data for the VDG to output as video. During the active display time (one frame of video) these addresses automatically refresh the memory devices. During the vertical retrace time, the SAM puts out refresh addresses. The microprocessor can access the memory at any time E is high and is therefore not affected.

114 March 1981 © BYTE Publications lnc

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BYTE March 1981

A

/

V

/

A

D0-D7

Y VDG DATA Y

X PROCESSOR Y DATfl A /

OUTPUTS Z0-Z7

W VDG/REF Vf/\/ \l\l\l VALID VOG/REF V V VpROCESSORV V V pb

Aa^dVss ft7wW°A columnTddress A A A"°" *™«^\h\

OCESSOR COLUMN ADDRESS

I

f

A

/

\

V

J

V

[

Figure 8: Diagram of a typical dynamic-memory refresh cycle. The SAM provides every dynamic memory with a signal on each row address, as required, to refresh the data contained within.

The VDG supports one

alphanumeric mode, two

semigraphic modes, and eight full

graphic modes.

Programming the VDG

The VDG has 5 mode-control pins that determine how the address lines behave and how the data that is obtained from the memory is to be interpreted. In this system, these lines are connected to lines PB3 thru PB7 of PIA2. The data-output register for this device is located at address hexadecimal FF22. The microprocessor can write directly to this port to select the VDG mode. In fact, Extended Color BASIC has a statement, PMODE, to do just this.

The VDG has one alphanumeric mode (using its internal character generator or an external one), two semigraphic modes, and eight full-graphic modes. The modes and the way the mode-control pins must be programmed are shown in table 5.

The alphanumeric mode is the one used by BASIC to print on the screen. The VDG sequentially reads 512 bytes from memory for each TV frame. The data is interpreted as character codes, with the first byte corresponding to the top left corner ("home" position). There are 16 rows of 32 characters for a total of 512 characters on the screen. The character code is given in table 6.

Lowercase characters are displayed as inverted (light characters on a dark background). This is done by tying bit 6 (DD6) of the VDG to the INVERT pin. Because this bit is set in all lowercase numbers, they are inverted.

To support the SET and RESET commands in Radio Shack's Level I BASIC, data line DD7 onjhe VDG is connected to the alpha/semigraphic pin (A/S). Whenever

this bit is set, the VDG will interpret the data in the manner shown in table 5, under the semigraphic-4 mode. Instead of displaying a character, a colored block that is divided into four smaller blocks is displayed. The code in the byte read from memory determines which pattern of blocks is shown and what color it is. Using the smaller element within the block as a pixel, this gives a grid of 64 by 32 blocks, which are the dimensions of the SET and RESET commands. The other semigraphic mode is similar to this, but each large block is divided into six blocks (instead of four) and has a choice of two sets of four colors, controlled by the CSS (Color Set Select) pin. (Refer to the semigraphic-6 mode in table 5.)

The remaining eight modes are of the bit-mapped graphic type. They require 1, 1.5, 2, 3, or 6 K bytes of memory, depending on the mode. Basically, the data in memory is interpreted as pixels. In the four-color modes (1-C, 2-C, 3-C, and 6-C), each pixel is represented by 2 bits, selecting one of four colors. The set of colors is selectable by the CSS pin. In the two-color modes (1-R, 2-R, 3-R, and 6-R), each bit is mapped one-to-one on the screen. If the bit is set, the pixel is colored, and if it is not set, the pixel is black. The color set can be changed so the pixel can be either buff or green; color sets are controlled by the CSS pin. The resolution of these modes varies from 64 by 64 to 256 by 192 pixels horizontal and vertical respectively.

To use these graphic modes, you simply program the VDG by writing the mode code into the PIA output register, and write to the "screen memory" addresses. The only problem is that the VDG's address lines are not connected to any memory. As mentioned before, the SAM provides the addresses and the VDG interprets the data from the memory, so the SAM must be programmed to be in the same mode as the VDG in order to get a mean

Text continued on page 120

116

March 1981 © BYTE Publications Inc

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BYTE March 1981

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Hexadecimal

Digit

Low-Order Hexadecimal Digit 0123456789ABCDEF

©ABCDEFGHUJKLMNO PQRSTUVWXYZ[\]t~

0123456789: ;<=>?

@ A B C

D E F G H

U

J K L M N 0

P Q R S

T U V W X

Y

Z [ \ ] I

! " #

$ % & ' (

)

* + ,-■/

0 12 3

4 5 6 7 8

9

: ; < = > ?

Table 6: Codes for the characters stored in the VDG's internal character generator. The lower section contains inverse-video characters, dark characters on a light background.

Text continued from page 116:

ingful display.

Programming the SAM

With a SAM in the system, the memory map is pretty much fixed. The SAM directly decodes the addresses from the processor to access memory, and provides device selects for the rest of the sytem on the SO thru S2 pins. These pins are decoded by a 3-to-8 decoder (74LS138) to get the active-low select signals for the rest of the system. Refer to the memory map shown in figure 9.

The reset vector and interrupt vectors at the top of the map are mapped from hexadecimal FFF2 thru FFFF to BFF2 thru BFFF. This allows these vectors to be stored in the 8 K-byte BASIC ROM beginning at address hexa

decimal A000. The addresses of the two PIAs, the second ROM, and the off-board ROM cartridges are also shown in figure 9.

The block of addresses from hexadecimal FFCO to FFDF are the locations of the SAM registers. The SAM is programmed and its various options selected by writing to these locations. The data is immaterial since the data bus is not connected to the SAM. Each register bit has two unique locations, an even location and an odd one. Writing to the even location will clear the register bit. Writing to the odd location will set the bit. By encoding the bits, and accessing the appropriate locations, the SAM can be programmed.

The memory map in figure 9 shows the modes and the locations associated with each. S stands for set and C for clear in the diagram. The programmable attributes include:

•VDG mode —mode of address lines during VDG refresh

time.

•Display offset —the base address of the memory used by

the VDG is specified here. This is the address of the pixel

in the upper left-hand corner of the screen in graphic

mode. Programmable in Vi K pages.

•Memory size —4 K-bit, 16 K-bit or 64 K-bit dynamic

memories or a full map of static memory and I/O.

•Microprocessor clock rate —can be set for 0.8, 1.8 MHz

or address-dependent rate.

•Page —allows two 32 K-byte memory pages between

hexadecimal 0000 and 7FFF.

The VDG mode bits in the SAM must be programmed to match the mode selected for the VDG on its mode pins. Table 7 shows the correspondence between the SAM and the VDG modes. If the two modes do not agree, interesting results can be obtained. Some of these "mixed" modes include graphics mixed with alphanumerics.

The VDG address offset specifies where the SAM should start the address counters. Figure 10 shows the address sent by the SAM as a function of this offset. This allows the VDG display to be "paged" through memory in 512-byte pages, allowing fast page swapping for animation, etc. On reset, BASIC will set the offset to hexadecimal 400 so all the screen output of the BASIC interpreter is at locations hexadecimal 400 thru 5FF. Try POKEing to these locations to use the alphanumeric and semigraphic modes.

The Extended BASIC supports the higher-resolution

Text continued on page 124

120 March 1981 © BYTE Publications In

Circle 65 on inquiry card.

Introducing

quality print at matrix speed.

rot only $1295!

Until now, word processing output was a slow, expensive proposition. Vbu could pay thousands for a slow, letterquality character printer. Or give up print quality for matrix speed and price.

Butthat was before Paper Tiger'" 460 offered you a better choice.

The new Paper Tiger 460 is the first matrix printer with high-density dot matrix characters plus high speed. At a low price.

The secret? A unique nine-wire, staggered matrix head provides overlapping dots in both horizontal and vertical planes. The result is dense, high-quality characters you'll be proud to show off.

What's more, Paper Tiger 460 gives you a combination of features simply not available on any other printer, at any price. Like bi-directional, logic-seeking printing at speeds in excess of 150 characters per second. Microprocessor electronics, with built-in diag nostics and self-test. Proportional spacing. Automatic text justification. DotPlot'" high

Integral Data Systems stands re.performance printers ideally so printer, the IDS 460, offers feat

Automatic proportional spacing, processing systems, plus the cap resolution of 84 by 84 dots per

Paper Tiger 460 Print Sample

resolution graphics option. RS232 and parallel interfaces. And more.

But its most important feature is high reliability. Paper Tiger 460 is designed to be tough and dependable. It has rugged, stepper-motor head and paper drives. A new rugged ballistic-type print head.

Circle 66 on inquiry card.

And its simple, chassis-mounted cartridge ribbon lasts up to four times longer than cassette or spool ribbons.

Paper Tiger 460 is the one printer that gives your Apple/ TRS-80,*or other small business computer both data processing and word processing output. At a price you can afford. Get your paws on Paper Tiger 460, and join the tens of thousands of satisfied Integral Data Systems users. For the name of the Paper Tiger dealer nearest you. Call us toll-free: 800-258-1386. (In New Hampshire, Alaska, and Hawaii, call (603) 673-9100.) Or, write for complete specifications. Integral Data Systems Inc., Milford, New Hampshire 03055.

■w)) Integral Data Systems, Inc.

*Suggested single-unit U.S. retail price.

t Apple is a trademark of Apple Computer Inc.

tTRS-80 is a trademark of Radio Shack, a division of Tandy Corp.

HE

8 *~~ BITS

KADECIMAL

6809 6809 \DDRESS ADDRESS

S2,S| , So VALUE LABEL DEFINITION

s

f6809 VECTORS?)

-<FFFF

Lffoo

<C000 ■< A000 -<8000

< 4000 -<1000

» » r- \

SAM CONTROL, )^

MEMORY

(USUALLY

R0M2)

(S=3)

7/ 1

FFFF

L.S.*

RESET

s/o ;

FFFE

M.S.

FFFD

L.S.

NMI

FFFC

M.S.

FFFB

L.S.

SWI

FFFA

M.S.

FFF9

L.S.

IRQ

FFF8

M.S.

FFF7

L.S.

fTrq

FFF6

M.S.

FFF5

L.S.

SWI2

FFF4

M.S.

FFF3

L.S.

SWI 3

FFF2

M.S.

FFF1

RESERVED

(FOR FUTURE MPU ENHANCEMENTS)

DO NOT USE!

(S=2)//

FFFO

FFEF

/ /'

1

FFEE

FFED

FFEC

MEMORY

(USUALLY

ROMj)

(S=2)

FFEB

FFEA

FFE9

FFE8

FFE7

FFE6

FFE5

64K STATIC

64K>|

16K >DYNAMIC

4K J

1.8 MHz ONLY

1.8 MHz ONLY

0.9/1.B MHz 1 TRANSPARENT

FFE4

( = 0)

FFE3

FFE2

MEMORY

(USUALLY

ROM0)

(S=l)

FFE1

FFEO

FFDF

S*

TY

MAP

TYPE

FFDE

C

FFDD

S

Ml

MEMORY SIZE

1

1

0

0

FFDC

C

FFDB

S

MO

1

0

1

0

1—0.9 MHz ONLY 1 REFRESH

FFDA

C

I

FFD9

S

Rl

MPU RATE

1

1

0

0

FFD8

C

MEM (S = 0 IF (S = 7 IF

ORY R/W =1) R/W=0)

I ,

FFD7

S

RO

1

0

1

0

FFD6

C

FFD5

S

PI

PAGE #1

\ MPU ADDRESSES FROM 0000 TO 7FFF J APPLY TO PAGE #1 IFPl = 'l'

FFD4

C

FFD3

S

F6

DISPLAY OFFSET

(BINARY)

1

>

FFD2

C

1 ADDRESS OF " UPPER-LE FT-HAND DISPLAY ELEMENT

FFD1

S

F5

' = 0000 + (1/2 K • OFFSET)

FFDO

C

DMA

G6R, G6C

G3R

G3C

G2R

G2C

GIC, GIR

(S»7J /1

FFCF

S

F4

FFCE

C

/ /' / /' / /'

|

FFCD

S

F3

FFCC

C

FFCB

S

F2

FFCA

C

FFC9

S

Fl

FFC8

C

FFC7

s

FO

1—Al AF S4 SK

FFC6

C

\

FFC5

s

V2

VDG MODE

(SAM)

1

1

1

1

0

0

0

0

FFC4

C

FFC3

s

VI

1

1

0

0

1

1

0

0

FFC2

C

FFC1

s

VO

1

0

1

0

1

0

1

0

FFCO

c

FFBF

RESERVED : DO NOT USE!

J REGISTERS OR SPECIAL I/O

FF60

A

FF5F

' EXTERNAL CS l/02

(S-6) /,

FF43

FF42

—

4K

■ 1

'///

FF41

FF40

7/A

FF3F

PIA 1 I/O]

(S=5) /

FF23

FF22

'///

FF21 FF20

'NO TE:

M.S. 2 MOST SIGNIFICANT

///>

FF1F

? PIA 0

l/00 (0.9 MHz)

L.S. s LEAST SIGNIFICANT

V J

r — p

(S^)'//

///

FF03

S = SET BIT 1(ALL BITS ARE CLEARED C = CLEAR BIT J WHEN SAM IS RESET.)

FF02

FF01

///

FFOO

Figure 9: Memory map of the Color Computer address space. The general division of addresses is provided at the left, while the SAM programming registers and the processor-interrupt vectors are expanded at the right.

122 March 1981 © BYTE Publications Inc

4*

A microcompufer for everyone at

a Micro Price

The UlicrofkeJ - a new generation of

miniature computers

A COMPLETE COMPUTER for $149.00 for 1K Kit

The unique

and valuable

components of the MicroAce

The MicroAce is not just another personal computer. Quite apart from its exceptionally low price, the MicroAce has two uniquely advanced components: the powerful BASIC interpreter, and the simple teach yourself BASIC manual.

The unique versatile BASIC interpreter offers remarkable programming advantages:

• Unique 'one-touch' key word entry: the MicroAce eliminates a great deal of tiresome typing. Key words (RUN, PRINT, LIST, etc.) have their own single-key entry.

• Unique syntax check. Only lines with correct syntax are accepted into programs. A cursor identifies errors immediately. This prevents entry of long and complicated programs with faults only discovered when you try to run them.

• Excellent string-handling capability takes up to 26 string variables of any length. All strings can undergo all relational tests (e.g. comparison). The MicroAce also has string input to request a line of text when necessary. Strings do not need to be dimensioned.

• Up to 26 single dimension arrays.

• FOR/NEXT loops nested up 26.

• Variable names of any length.

• BASIC language also handles full Boolean arithmetic, conditional expressions, etc.

• Exceptionally powerful edit facilities, allows modification of existing program lines.

• Randomise function, useful for games and secret codes, as well as more serious applications

• Timer under program control.

PEEK and POKE enable entry of machine code instructions, USR causes jump to a user's machine language sub routine.

• High resolution graphics with 22 standard graphic symbols.

• All characters printable in reverse under program control.

• Lines of unlimited length.

'Excellent value' indeed!

For just $149.00 (including handling charge) you get everything you need to build a personal computer at home... PCB, with IC sockets for all ICs; case; leads for direct connection to a cassette recorder and television (black and white or color); everything!

Yet the MicroAce really is a complete, powerful, full facility computer, matching or surpassing other personal computers at several times the price.

The MicroAce is programmed in BASIC, and you can use it to do quite literally anything, from playing chess to managing a business.

The MicroAce is pleasantly straightforward to assemble, using a fine tipped soldering iron. It immediately proves what a good job you've done: connect it to your TV ... link it to the mains adaptor ... and you're ready to go.

Fewer chips, compact design, volume production-more power per Dollar!

The MicroAce owes its remarkable low price to its remarkable design: the whole system is packed on to fewer, newer, more powerful and advanced LSI chips. A single SUPER ROM, for instance, contains the BASIC interpreter, the character set, operating system, and monitor. And the MicroAce IK byte

Post and Packing FREE (Add 6% Tax for Shipments inside California)

RAM (expandable to 2K on board) is roughly equivalent to 4K bytes in a conventional computer typically storing 100 lines of BASIC. (Key words occupy only a single byte.)

The display shows 32 characters by 24 lines.

And Benchmark tests show that the MicroAce is faster than all other personal computers.

No other personal computer offers this unique combination of high capability and low price.

The MicroAce teach-yourself BASIC manual.

If the features of the BASIC interpreter mean little to you-don't worry. They're all explained in the specially written book free with every kit! The book makes learning easy, exciting and enjoyable, and represents a complete course in BASIC programming-from first principles to complex programs. (Available separately purchase price refunded if you buy a MicroAce later.) A hardware manual is also included with every kit.

The MicroAce Kit:

$149.00 with IK COMPLETE

$169.00 with 2K

Demand for the MicroAce is very high: use the coupon to order today for the earliest possible delivery. AM orders will be despatched in strict rotation. If you are unsuccessful in constructing your kit, we will repair it for a fee of $20.00, post and packing FREE. Of course, you may return your MicroAce as received within 14 days for a full refund. We want you to be satisfied beyond all doubt and we have no doubt that you will be.

Z80 A microprocessoi chip, widely recognised as ihu best ever made.

Sockets lor TV, cassette recorder,

power supply,

SUPER ROM,

mmmmmmmmm mmmmmmmm\

Your MicroAce kit contains...

• Printed circuit board, with IC sockets for all ICs. Complete components set, including all ICs all manufactured by selected world-leading suppliers. New rugged keyboard, touch sensitive, wipe clean. Ready-moulded case. Leads and plugs for connection to domestic TV and cassette recorder. (Programs can be SAVEd and LOADed on to a portable cassette recorder,) Mains adaptor of 600 mA at 9VDC nominal unregulated. FREE course in BASIC programming and user manual.

JOIN THE REVOLUTION - DON'T GET LEFT BEHIND - ORDER YOUR MICROACE NOW!!

Send Check, Money Order or quote your Credit Card No. to: MicroAce 1348 East Edinger, Santa Ana, California, Zip Code 92705. or phone (714) 547 2526 quoting your Credit Card Number.

Quantity

Description

TOTAL

MicroAce Kit 1K

$149.00

MicroAce Kit 2K

$169.00

Manual

$10.00

IK Upgrade Kit

$29.00

Shipmen add 6%

Is inside California TAX

TOTAL

Amex. Diners Check

Money Order Master Charge Visa

I I

_ Nan I Adt | City

Card No..

Exp. Date.

.Zip.

Circle 67 on inquiry card.

BYTE March 1981

123

Synchronous Address

Mode

Video Display Generator Signal

s M

ultiplexer

Signals

GMO

G/A

0

GM2

X

GM1

X

EXT/1

0

CSS

X

v2

v,

Vo

Internal alphanumeric

0

0

0

External alphanumeric

0

X

X

1

X

0

0

0

Semigraphic-4

0

X

X

0

X

0

0

0

Semigraphic-6

0

X

X

1

X

0

0

0

Full graphic 1-C

0

0

0

X

0

0

1

Full graphic 1-R

0

0

1

X

0

0

1

Full graphic 2-C

0

1

0

X

0

1

0

Full graphic 2-R

0

1

1

X

0

1

1

Full graphic 3-C

1

0

0

X

0

0

Full graphic 3-R

1

0

1

X

0

1

Full graphic 6-C

1

1

0

X

1

0

Full graphic 6-R

1

1

1

X

1

0

Direct memory access

X

X

X

X

X

1

1

Table 7: Mode correspondence

between the

SAM an

d the VDG.

A15 A14 A13 A12 All A10 A9 AB A7 A6 A5 A4 A3 A 2 Al AO

<=s

F5

F4

F3

?2

Fl

PO

0

0

0

0

0

0

0

0

0

MSB LSB

Figure 10: Mapping of the video-display refresh address. The SAM uses a 7-bit offset to determine the start of video-display memory. This allows the use of 512-byte "pages" for display refreshing, making it possible to page through memory to create fast animation effects, etc.

Text continued from page 120:

graphics and can also allocate more memory for multiple pages, up to eight. It provides graphic operations, such as LINE, DRAW, and CIRCLE, that are fast enough to allow the programming of real-time games using the joysticks as controllers.

Memory type is self-explanatory. The SAM must be programmed for the type of memory devices used in the system to produce the correct timing signals. If 16 K-bit circuits (MCM4116 or the equivalent) are used, pin 35 can be used for RASl. This is needed to select a second bank of devices to provide 32 K bytes of memory. One way to do this on the Color Computer is to piggyback a second set of eight MCM4116s on top of the existing integrated circuits, paralleling all the pins except for the RAS pin. When this is jumpered to pin 35 on the SAM, the system then has 32 K bytes of user-programmable memory.

The microprocessor clock rate is also programmable. There are three modes, as shown in figure 9. In mode 0, the clock rate is fixed at one-sixteenth the crystal frequency. In this case, that is 895 kHz. Mode 2 gives a fixed rate of one-eighth the crystal frequency, or 1.8 MHz. This can be used with an MC68B09E, a 2 MHz version of the microprocessor. However, there are no memory or VDG addresses output in this mode, so don't use it.

Mode 1 is the most interesting. It gives a dual-rate clock of 895 kHz or 1.8 MHz depending on the address used in the bus cycle. When the processor accesses addresses from hexadecimal 0000 to 7FFF and FF00 to FFlF, the lower rate is used, allowing for slower memory and peripherals. When all other addresses are accessed, the processor runs at 1.8 MHz. Using fast ROMs will almost double the speed of the system because a majority of the microprocessor's memory references are to fetch op

codes. If you want to try this, execute the following BASIC statement:

POKE 65495,0

This will set bit R0 of the microprocessor rate register at location hexadecimal FFD7 and put the SAM into the dual-rate mode. If your microprocessor can run at the higher speed (a pretty good bet), you will see the changing-color cursor flashing about twice as fast as normal. Your BASIC programs will now run about twice as fast, too. There is one problem, though —don't try to use the SOUND, CLOAD, or CSAVE statements in this mode. The PIA used by these statements is at location hexadecimal FF20 and it will probably not run at the higher speed.

The other two registers do not apply to the Color Computer. The Map Type bit chooses a mixed programmable/read-only type of system such as the Color Computer or a fully programmable system such as a disk-based one. The Page bit allows two 32 K-byte pages of memory to be accessed between locations hexadecimal 0000 and 7FFF. This can't be done on this system.

Keyboard Scanning

The keyboard is configured as an 8 by 7 matrix of keys. The Color Computer uses a software routine to encode the keyboard in a manner similar to that of the TRS-80 Model I. This is done by shifting a 0 through the B port of PIA IC8. The B port drives the 8 rows of the keyboard; the 7 columns are connected to the A port of IC8. The A port has internal pull-up resistors that provide a logic 1 level unless a key is depressed. When the shifted 0 occurs on the row of the closed key contact, the low level is passed to port A. By repeating the scanning procedure several times, debounced inputs are recognized.

If you need to monitor the keyboard during a program, a function (INKEYS) is provided. The BASIC statement

A$ = INKEYS

will return a character if a key is closed when the function is called. An example use of this function would be to monitor the keyboard during a 'Tank" game for direction

124

March 1981 © BYTE Publications Inc

Circle 76 on inquiry card.

The largest selection of software from the world's largest software publisher.

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luct

DISK OPERATING SYSTEMS

CP/M CONFIGURED FOR: APPLE II

DIGITAL MICROSYSTEMS FDC3 DURANGOF-85 HEATH H8 AND H89 ICOM MICRO DISK ICOM 3712 ICOM 3812

ICOM 4511/PERTEC D3000 INTEL MDS

MICROPOLIS FLOPPY DISK MITS/ ALTAI R MOSTEKMDX NORTH STAR 0SIC3

PRO-TECH HELIOS TRS-80MODELI TRS-80 MODEL II TRS-80 MODEL III ZENITH Z89 MP/M FOR INTEL MDS.

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CORVUS WITH APPLE II SOFTCARD CORVUS WITH S100 AND TRS-80

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muSIMP NEVADA COBOL PASCAL/M PASCAL/MT PASCAL/MT + PASCAL/Z PL/l-80 SMAL/80 S-BASIC TINYC W'SMITHSC COMPILER XYBASIC

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It used to be that computers would do everything but spell.

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No matter what is on your word processor- a letter, presentation, thesis, manuscript-bad spelling makes a bad impression. Now you can correct spelling errors automatically with a new software system from Lifeboat. Called Microspell, it converts your microprocessor into a spelling proofreader. Microspell scans each word you write and tells you every time it finds a misspelling. Automatically, it will print alternatives, and you select the correct word. Words you're unsure of? Microspell will be your dictionary, too.

Microspell has a basic 20,000 word dictionary, and you can add to it yourself. Add technical words, create auxiliary dictionaries, special expressions, and acronyms.

Complete with full dictionary, all utilities, and a demonstration file, Microspell from Lifeboat costs $249.

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DC 300 DATA CARTRIDGE HEAD CLEANING DISKETTE FLIPPY DISK KIT FLOPPY SAVER

Program names and computer names are generally trademarks or servicemarks of the author or manufacturing company.

All software products have specific requirements forhardware and additional associated software (e.g. operating system or language).

All products are subject to terms and conditions of sale.

Copyright @ 7987 Lifeboat Associates. No portion of this advertisement may be reproduced without prior permission.

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ADDS Multivision

AVL Eagle ... Altair 8800

AllDS

Apple CP/M 13 Sector . Apple CP/M 16 Sector BASFSystem 7100 Blackhawk Micropolis

Mod II

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CDS Versatile 3B

CDS Versatile 4 ... COMPAL-80

CSSN Backup .

Cromemco System 3 . ..

Cromemco Z2D

Delia Systems

Digi-Log Microterm II

Digital Microsystems . A1

Durango F-85 . , , RL

Oynabyte DBB/2 Rl

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Exidy Sorcerer - Lifeboat

CP/M ... .02

Heath H8 - H17/H27disk P4 HealhH89 - LiteboalCP/M P4 Healh H89 * Magnolia

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IMS 5000 RA

IMS 8000 . A1

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8063/8360/8963 A1

Intertec Superbrain DOS 0 1 R7 Interlec Superbrain DOS 0 5 RJ Intertec Superbrain DOS 3 x RK

itertec Superbrain QD KontronPSl-80 MITS 3200-3202 MSD5 25in . Meca Delta-1 5 25 in Micfomalion Micropolis Mod I

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Freedom TRS-80 Model I ■

Micromation TRS-80 Model I

5 25 in

FEC

A1 TRS-80 Model I - Omikron

03 8 in A1

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A1 TRS-80 Model III RU

R3 Vector MZ 02 j

A1 VeclorSyslem 8 Q2

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keys and a "Fire" key. This would allow you to play a 'Tank" game without having a set of joysticks.

This type of converter is accurate to ± Vi the least significant bit, or in this case ±39 mV.

Digital-to-Analog Converter

The D/A (digital-to-analog) converter allows the Color Computer to send analog waveforms. These signals are used for the cassette output, sound to the video modulator, and as a reference signal for A/D (analog-to-digital) conversion.

Six of the eight port A lines are configured as outputs and buffered to drive a resistive adder network for analog signal generation, as shown in figure 11. The resultant analog signal ranges from 0 V to +5 V in 78 mV steps.

PART OF IC4 MC6821P

PA2 PA3 PA4 PA5 PA6 PA7

IC2 MC14050B

'~l

$>

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2 320K WA—i

15

160K -WV\—l

80K -AAA—*

12

40K -AAA—*

20K -VW

10 10K

VA 1

-o

ANALOG OUTPUT

I I

Figure 11: Schematic diagram of the Color Computer's digitalto-analog converter. In a rather simple scheme, the output lines of a parallel port drive a resistive adding network to provide conversion. The resulting analog signals are used for recording on a cassette, providing the video modulator with sound, and also as part of the analog-to-digital converter.

IC4

MC6821

u

:>

DIGITAL TO ANALOG CONVERTER (FIGURE 11)

\ AFMALUt.

/level

FROM JOYSTICKS

C21

1/2 MC14529

Figure 12: Diagram for the analog-to-digital converter circuit. Also used as the joystick interface, this circuit applies the successive-approximation method (see figure 13) to change analog signals to digital form.

Cassette Port

The Color Computer has a cassette port which connects to a low-cost recorder. Motor-control capability is included that allows the cassette recorder to be started or stopped as required. The motor can be turned on and off with the statements MOTOR ON and MOTOR OFF. This allows the user to fast-forward or rewind tapes without having to unplug connections to the Color Computer.

Data is output to the recorder from the D/A converter. If an oscilloscope is connected to the data-output line, pin 5 of the cassette jack, an 800 mV 1500 bps signal will be seen.

When data is loaded from the cassette recorder, the playback signal can be routed to the modulator sound input in a manner that allows you to monitor the cassette signal via the speaker of a television set. This is done with the AUDIO ON and AUDIO OFF statements.

The cassette data-output can be used for an analog output level because the D/A converter can be controlled by a user program. The motor-control relay can be used to control loads up to 6 V DC at 500 mA.

Joystick Interface

Two joystick ports are provided which allow full x,y directional control. Each joystick has a pushbutton for use with games (eg: paddle control for the Pinball game). Each joystick consists of two potentiometers, each connected across +5 V and ground. The wiper of each potentiometer is connected to the input of an analog multiplexer controlled by PIA IC8. The voltage level from each of the four potentiometers is routed to the A/D converter to get a digital value for the position. This value will range between 0 and decimal 63. The JOYSTK(j) function returns the digital value of the joystick position.

Analog voltage levels from the joysticks are digitized using a successive-approximation technique. This is one of the more popular methods of A/D conversion. The 6-bit D/A converter is used in a feedback loop to generate a known analog signal to which the unknown analog joystick input is compared. This technique is not as fast as a flash converter, nor is it as slow as a binary counter.

Figure 12 shows the block diagram for the successiveapproximation converter circuit. Figure 13 shows a flowchart for this approach. The D/A converter inputs are controlled by the microprocessor to form a successive-approximation register. The analog output is compared to the analog joystick input by the MLM339 comparator whose output is monitored by the MC6809E.

At the start of a conversion the MSB (most significant bit) of the D/A converter is turned on by the microprocessor, producing an output equal to half the full-scale value. This output is compared to the analog input and if it is greater than the joystick voltage, the microprocessor turns the MSB off. However, if the D/A output is less than the joystick voltage, the MSB remains on.

Following the trial of the MSB, the next most significant bit is turned on and again the comparison is made

126 March 1981 © BYTE Publications Inc

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BYTE March 1981 127

between the converter's output and the joystick voltage. The same criteria apply and this bit is either kept on or turned off. This procedure of testing each bit continues four more times until the 6 bits of the D/A converter have been set to the proper level.

Once the conversion is complete the microprocessor reads the joystick output by reading port A of PIA IC4. The internal structure of port A allows a read of the port to sample the output logic levels. Now the Color Computer has the digital value for the joystick voltage. The time necessary to do this conversion is constant and does not vary with the analog voltage level.

Note that the Color Computer has an on-board A/D converter that accepts a signal between +5 V and ground and can digitize it with less than a 40 mV error. This means you can use the appropriate joystick inputs to monitor various analog voltages. The switch inputs are connected to the PIA (the left switch to IC8 pin 3, PAl; and the right switch to IC8 pin 2, PAO). You can write a progam to monitor these bits for use with external devices. Figure 14 shows the connectors for the joysticks (which are not shown in the TRS-80 Color Computer Operation Manual).

usable.

Expansion Port

The expansion port provides the capability to interface almost anything to the Color Computer. Table 8 lists the pins and their functions. Note that the entire address bus is brought out. There is also a decode-defeat pin which disables the 74LS138 that decodes ROMs and peripherals. This allows the expansion port to redefine the memory map. For instance, a flip-flop could be toggled to remove the BASIC and Extended BASIC ROMs from the memory map and replace them with programmable memory. A disk-controller board could also contain 48 K bytes of memory to fill the system from address hexadecimal 0000 to FF60.

The Vector Graphic company makes a wire-wrap prototype board (part number 4609) that fits the expansion connector of the Color Computer. This allows you to build your own peripheral boards. We are working on an interface to the General Instrument "Cricket" sound generator. The output from this circuit can be routed to the video modulator through a pin on the expansion connector. If you want, you can also build your own game

RS-232 Interface

An RS-232 interface is also provided. This allows you to connect all manner of devices to the Color Computer. The standard RS-232 Transmit Data, Receive Data, and Carrier Detect signals are provided. This is the fundamental signal subset used by most devices. Tandy sells an off-the-shelf line of printers and a modem that are readily

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START SUCCESSIVE APPROXIMATION ROU

TING/

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-J

SET BIT I OF D/A INPUTS

RESET BIT I OF D/A INPUTS

1 = 1-1

READ IC4 PORT A (AND SHIFT RIGHT TWO BITS) FOR DIGITAL LEVEL

c

END

D

Figure 13: Flowchart of the successive-approximation algorithm used by the Color Computer.

128

March 1981 © BYTE Publications In

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CONNECTED TO +5V THROUGH 100JI RESISTOR

Figure 14: Pin designations of the Color Computer joystick connectors. The connectors will mate with a standard 5-pin DIN plug, and any signal within the A/D converter's range may be monitored under program control.

Expansion Port Pin

Description

pin

function

pin

function

1

-12 V

2

+ 12 V

3

HALT

4

Nonmaskable Interrupt

5

RESET

6

E

7

Q

8

CB1 of IC4

9

+ 5 V

10

DO

11

D1

12

D2

13

D3

14

D4

15

D5

16

D6 R/W

17

D7

18

19

AO

20

A1

21

A2

22

A3

23

A4

24

A5

25

A6

26

A7

27

A8

28

A9

29

A10

30

A11

31

A12

32

C000 thru FEFF

33

Ground

34

Ground

35

Analog In

36

FF40thru FF5F, CS

37

A13

38

A14

39

A15

40

Decode Defeat

Table 8

Signals ava

table

at the expansion port.

cartridges. If you want them to auto-start like the Tandy cartridges, connect pins 7 and 8 together. This runs the Q clock into the CB1 input of PI A IC4, causing an FIRQ interrupt. The FIRQ interrupt-service routine jumps to hexadecimal C000 and starts execution. There is also a device select on pin 32 that is decoded from hexadecimal C000 to FEFF.

Summary

We have tried to completely describe the architecture of the Color Computer and deduce the reasoning behind the design trade-offs. Tandy certainly is to be complimented on the amount of "bang for the buck" —every part is fully used and several innovative design ideas are evident. We believe that the Color Computer has the capability to surpass the Model I in sales.

In a later article we will take a detailed look at the Extended BASIC and discuss its capabilities. We are currently implementing several popular video games in BASIC. Once the algorithms are proven, we plan to convert them to machine language to increase the speed, although with the power of the Extended BASIC we may not have to.B

Circle 70 on inquiry card.

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'VisiCalc i s a trademark of Personal Software, inc. CP/M and MAC are trademarks of Digital Research, Inc. The CP/M Users Group is not affiliated with Digital Research. T/MAKER is a trademark of P. Roizen.

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BYTE March 1981

131

What Is Good Documentation?

Jim Howard

150 Ramona Place

Camarillo CA 93010

As more and more people discover the joys of owning a microprocessor the need for good documentation will continue to grow. Information will be needed at all levels, from detailed hardware and software documentation to descriptions of which buttons to push to play your favorite game.

Who will provide this information? The simple answer is that those who know will tell those who don't know. It sounds simple, but it's not. Everywhere, complaints are made about documentation—"inadequate," "erroneous," "over my head," "bad or nonexistent," and so on. All too often, companies market excellent systems with poor or sketchy documentation, resulting in unhappy customers and unsatisfactory sales.

It's a common mistake to believe that because somebody is an expert in a subject, he can explain it to others. For example, it's assumed that a professor who knows a subject inside and out can pass on this information to students. However, whether he can or cannot depends on something else besides his knowledge of the subject. It depends on his ability to put himself in the place of the users, the students, to begin where they are,

using their language and their knowledge level. (Of course, if there is a failure to communicate, it is the students who fail, not the professor!)

The microprocessor industry is a classic example of the communication problem. Aside from a few shining lights, microprocessor literature suffers from a bad case of "the jargons." The problem was not as serious while the technology was being pursued by only a few hobbyists, who like to work things out for themselves. Now

Aside from a few

shining lights,

microprocessor

literature suffers from

a bad case of "the

jargons."

that the public is becoming involved in large numbers, the information must adapt to the customer, not the other way around.

Many could undoubtedly do a better job of communicating if they followed a few principles. But doing

this requires conscious dedication. And, of course, it requires principles. Those principles are what this article is about.

To translate the jargon of the expert into terms meaningful to the rest of the world, we need an interpreter. Such an interpreter is similar to the compiler or interpreter used in computers, which translates the source language into one the machine understands. In both cases, the source language is provided by the computer expert. The machine is the user in one case, the public in the other.

Information Design

The interpreter we require can best be referred to as information design. This term is better than the common term "technical writing," in that it indicates what really is required—conscious, step-by-step design. Writing is just one aspect of presenting understandable information. In fact, technical writing is similar to writing code for a computer program. If the planning and structure are sound, the writing almost takes care of itself.

There are many aspects of information design, not all of which can be

• Content defines the breadth and depth of the material in a document, and is best specified by a topic diagram. Consistency and uniformity of treatment are revealed by such a diagram: One topic should not be treated in great detail and others of equal importance hardly mentioned. The breadth and depth should fit users' needs—all relevant material included, no unnecessary redundancies, and sufficient detail to allow users to understand the explanation or perform the job.

• Organization gives shape and

Information Design Principles

direction. The users always know where they are, where they have been, and where they are going. Indexes and headings make the organization visible to users, so that information is located easily and quickly. Material is grouped and sequenced to flow logically and naturally from one topic to another. A top-down approach is used, to provide an overall structure before confusing users with details. Introductions and summaries tie pieces together both forward and backward, and reinforce for long-term memory.

• Format makes the information understandable through language and illustrations. Language speaks to one half of the brain—the verbal, linear side. Simple vocabulary and short, direct sentences make for ease of understanding. Illustrations speak to the other half of the brain—the nonverbal, spatial side. Illustrations are most effective when they are near the relevant text and are keyed to it through call-outs and highlights. Working together, words and illustrations present the whole "picture" as neither can alone.

132 March 1981 © BYTE Publications lnc

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covered here. What is necessary is that a few key principles are made clear.

The basic objective of information design is usability. Whatever the user intends to do—write a program, assemble a piece of hardware, learn how a system works—the documentation must serve this purpose.

Although this may sound trivial, if you're writing a technical document, it's surprising how easy it is to lose sight of this overall requirement after page 1. The presentation can become an ego trip without your realizing it. On the other hand, it's hard to go

wrong if you consistently keep the usability objective in mind.

How do we determine if a document is usable? Whatever the type of document—operator's manual, maintenance procedure, reference manual, training program—it has some purpose. Its purpose may be to explain a concept, describe the operation of a piece of equipment, or guide a person through an assembly procedure.

To be usable, the document must take the users from a state of incomplete knowledge about some subject to a condition of more complete knowledge. If it's a procedure, the in

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formation must guide the users through the task. In any case, the document must take them from "here" to "there."

That's what information design does: It starts where the users are and builds step by step. The information designer first asks who the users are. Then he puts himself in their place and asks, "What will they understand, with their experience? What is their technical knowledge and vocabulary? How can they best be helped?"

Next, he builds step by step. He breaks up complicated subjects into simpler parts. He leads the users gradually into new territory, helping them make their own discoveries. With each step their confidence grows and they want to learn and do more. At the end, the users know they have succeeded—and, therefore, so has the information designer.

The Elements of Information Design

If we are going to start where the users are and build step by step, we need a plan of action. We need to decide:

• what information to include in the document

• how to organize it

• how to present it so it's understandable

We'll discuss these aspects under the headings of Content, Organization, and Format.

Content

The content of a document is the specific technical material contained in it. This should be carefully defined by boundary lines set down by the information designer.

Content really has two aspects: what information is included (breadth) and what is its level of detail (depth). A simple example will illustrate the important difference between breadth and depth: An operator's manual for a computer system might tell you to "remove and replace the printer's print wheel as necessary." The subject of print wheel replacement is thus "covered" in the manual; that is, in terms of breadth, it is part of the content. However, the lack of "how to" details may make this information of little use to many

Circle 73 on inquiry card.

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printer users. Thus the proper depth of information is not part of the content.

A good tool to help a writer of documentation analyze breadth and

depth is a topic diagram (figure 1), which is an arrangement of topics in boxes at different levels, with lines joining related topics. It serves a purpose similar to that of an outline, but

BREADTH

SUBJECT OR

PROJECT

INTRODUCTION

TOPIC 1

TOPIC 2

1.1

1.2

1.3

2.1

2.2

Figure 1: A topic diagram is a useful tool for determining the breadth, depth and consistency of a piece of writing. Although similar in content to an outline, the topic diagram provides a clearer visual check on how topics are handled. As shown, topics 1 and 2 are major topics at the same level. Neither is a subtopic of the other and both will be treated equally when the writing is done. Subtopics represent breakdowns of each major topic. As additional topics and subtopics are added the diagram can extend downward and to the left and right.

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provides an easier visual check on such elements as breadth, depth, and consistency of treatment.

In figure 1, topics 1 and 2 are major topics at the same level in the diagram. They might be two major components of a system, or groups of software, or procedures. Neither is a subtopic of the other and they will be treated equally in the presentation.

Subtopics are shown under each major topic: 1.1, 1.2, 1.3 under topic 1, and 2.1 and 2.2 under topic 2. These represent breakdowns of each major topic. The diagram can continue on down to further depths of subdivision and can also be extended to the left and right as additional topics are added at a given level.

We can see that the breadth of the topic diagram, particularly at the major topic level, tends to indicate the breadth of content. The depth of the diagram indicates the depth of content. While this should not be considered an infallible guide, it is useful in preliminary planning.

Another use of a topic diagram is that it gives an idea of consistency of coverage. A glance at figure 1 will tell the writer if topics at the same level are being treated with some consistency in how they are subdivided, or if one topic is being pursued to greater levels of detail than others. Without such a guide, it's easy to cover one topic in great detail and give other topics at the same level only token treatment or overlook them completely.

Definition of content is as important for what is not included as for what is. Many technical documents include irrelevant information. This can be particularly annoying in procedural documents, when users are trying to accomplish an exacting task. They want to get on with it, but are continually being interrupted with extraneous remarks that belong in some other part of the document or should be left out entirely.

Figure 2 shows a topic diagram for this article. As you can see, in addition to defining content, such a diagram shows a preliminary organization or structure.

Organization

To proceed step by step, we need to know where we are going and a route to get there. In other words, we need structure, or organization. Informa

138 March 1981 © BYTE Publications Inc

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BYTE March 1981

139

disordered ping list, everything

tion must be grouped, sequenced, and related in order to be understood. Otherwise, it is merely a jumble of facts or ideas—a "shopIf we had to learn by rote memory from shopping lists, we'd be in big trouble. Once a good structure is established, all kinds of details can be hung on it and they will be understood and remembered.

Organization is also what makes information in a document easily accessible. Accessibility depends on both the overall structure of the document and how this structure is made visible to the user through indexing and headings. If information is organized properly, the user will be able to turn quickly to the information he wants. Once there, he will be able to continue with a minimum of routing to other parts of the document.

The importance of structure or organization can be illustrated by a very simple example—a telephone book. Have you ever stopped to think how useless a telephone book would be if the names were listed randomly rather than alphabetically? The important aspects of structure or organization include indexing and headings, grouping and sequencing, routing, and introductions and reviews.

Indexing and Headings

Indexing and headings are the means by which the organization of the document is made easily visible to users. A writer may actually have a good organization, but if it is not clear to users, it will not really have served its purpose.

Indexing as used here includes both the standard type of index found at the end of a document and the table of contents. The index should be set up with the idea that users will sometimes look for items alphabetically, as in a dictionary. Many items that are too small or too specific to be included in the table of contents are made accessible with a good index.

Often a table of contents can be usefully constructed in two parts: an overall table in front and more detailed tables with each major section of the document. This avoids an unwieldy table up front. Figure 3 provides an example of a two-part table of contents. The main table (on the left in the figure) would appear in the front of the document. Each major section would start with its own table of contents (on the right in figure 3) showing the more detailed headings and subheadings in the section.

A consistent set of headings serves to make information accessible. Headings also help users remember

WHAT IS GOOD

DOCUMENTATION

?

INFORMATION DESIGN

ELEMENTS OF INFORMATION DESIGN

CONTENT

ORGANIZATION

FORMAT

SUMMARY

Figure 2: A topic diagram written for this article.

140 March 1981 © BYTE Publications Inc

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where they are, which is just as important. Thus high-level headings should be repeated frequently, for example as a running head at the top of each page. Having the relevant headings always in front of the user makes the structure visible, and details are then assimilated more easily.

Grouping and Sequencing

The overall organization of the document is established by how the content material is grouped and sequenced. Again, the topic diagram is

useful during the planning stages in making visible the planned organization of the document.

Whether the document is procedural or descriptive, grouping of the topics should be based on a logical pattern and the relevance of different items. For example, procedural tasks normally performed together (such as the various steps required to start up a computer system) should be grouped together. In a system description, the individual descriptions of system components

CONTENTS LIST OF FIGURES LIST OF TABLES

1. INTRODUCTION

2. SYSTEM COMPONENTS

3. SYSTEM OPERATION

4. COMMUNICATIONS

2. SYSTEM COMPONENTS

2.1 CENTRAL PROCESSING UNIT

CONTROL PANEL MICROPROCESSOR DIRECT MEMORY ACCESS

2.2 DISK DRIVES

DRIVE CONTROLS NUMBER OF DRIVES DRIVE COMBINATIONS

2.3 VIDEO TERMINAL

DISPLAY SCREEN KEYBOARD

Figure 3: An example of a two-part table of contents. By using an overall table in the front of the document, and a more detailed table later, an initial unwieldy table is avoided where a user would be subjected to unwanted detail.

LONG-TERM MEMORY

SHORT-TERM MEMORY

Figure 4: Summaries and long-term memory. In the human brain, memory is divided into short-term memory and long-term memory. Although the capacity of long-term memory is large, all information must first pass through a short-term memory. When writing, the inclusion of summaries, reviews, and question-and-answer sections is an effective way of passing information into long-term memory.

would normally be grouped together, as in the example table of contents shown in figure 3.

Sequencing is one of the most critical parts of the structure. The user is being led step by step from the known to the unknown, from the simple to the complex. Here the topdown structuring principle frequently used in writing computer programs also applies. The sequence should begin at the top and give the readers the big picture before engulfing them with details. It is not unusual to begin reading a document and find yourself up to your ears in technical details before you really know what's going on.

Most equipment operations and human activities have a natural or normal sequence that should be preserved in the documentation. For example, you normally gather together all the tools and supplies required for an activity before starting; therefore, this information should logically precede the activity description. It is disconcerting to have to stop in the middle of a task and run to the hardware store to buy some item.

Routing

Once you start using a document it is inconvenient to have to refer to other parts of the document, or to other documents. The more often you are routed, and the more pages you have to thumb through to get there, the less useful the document. On the other hand, if all information is repeated at each point of need, a bulky document can result. Obviously, judgment is required in weighing these trade-offs. For example, you wouldn't want to tell a user how to solder a particular type of joint every time it came up—you would set aside a special section for this purpose. However, if a safety precaution applies to a number of different tasks in the document, it is better to accept the redundancy and repeat the precaution.

Introductions and Reviews

A general rule is to prepare users for what is coming and to remind them of where they have been. Proceeding through a document, users may forget where they are, forget what has gone before—and decide they didn't really want to learn this anyway. Information should be

142 March 1981 © BYTE Publications Inc

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designed to help users relate backward and forward and recognize and retain key points along the way.

Further, readers need introductory instructions to help them find and use information. For example, the numbering schemes for tasks or illustrations, the use of safety symbols, notes, cautions, and warnings, and the treatment of information about tools and supplies should be briefly explained. If these instructions are backed up by consistent information presentation (see Format section), users will quickly learn what to expect, no matter where they are in the document.

Simple reviews at key points reinforce information and help users re

tain it in memory. Human memory, to put it simply, consists of two parts, "short-term" and "long-term." Whereas capacity is very limited in STM (short-term memory), the capacity of LTM (long-term memory) is large indeed. The catch is that information can get to LTM only through STM. Summaries and reviews and question-and-answer sessions are effective ways of establishing information firmly in LTM. This important concept is illustrated in figure 4.

Format

Format usually has the rather narrow meaning of "physical layout of the page."Here the term is meant also

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The general rule is that language and illustrations should work together. Each is an effective way of presenting certain kinds of information, and relatively ineffective for other kinds. When combined properly, they form a powerful presentation technique.

People will readily admit that pictures can do things that words cannot and vice versa. And yet it is surprising how often we find ourselves reading words, words, words, when a visual or two would have helped the presentation considerably. Many ideas become clearer with an illustra

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BYTE March 1981

145

tion, and some kinds of information can hardly be communicated at all without one. If you want to tell someone what something looks like, show a diagram or a photograph.

It is known that the left and right sides of the brain are quite different. For most people, the left side is dominant and works mostly with linear, sequential logic (like a computer). It is also the verbal side and controls language.

The right side specializes in images, music, pictures—it deals in spatial and visual concepts, in contrast to the linear, verbal left brain. Schools, with their traditional emphasis on verbal skills, have tended to neglect the right side of the brain. People who are less adept with their left brain have suffered as a result. Einstein, for example, was a poor student in language, but had a great ability to visualize (see figure 5).

The ideal combination is words and pictures working together, each doing what it does best. In a procedure, for example, words can tell readers what to do and how to do it; pictures can tell them what it looks

^BpW'* V LEFT HALF (WORDS)

V

f |V x

Figure 5: The left and right sides of the human brain are very different. In most humans, the left side, which works mostly with linear and sequential logic, is dominant. The left side also controls verbal communications. The right side of the brain deals in spatial, visual, and more holistic concepts. One of the best ways of imparting information to the reader is through a combination of both words and pictures, thus enabling the reader to use both sides of the brain.

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146 March 1981 © BYTE Publications Inc

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like and where it is. For descriptive material, words and diagrams will do a good job of explaining and describing, provided they are working together. When you decide to use pictures to communicate with readers, follow the flow through step by step. Don't be content with offering an occasional "amazement diagram" and a "see figure so-and-so." You can perhaps wake up the right half of the reader's brain this way, but to get it working with the left half as a unit—whole-brain learning—make the words and pictures work together.

Here are some guidelines on how to do this, discussed under the following headings: keying text to illustrations, positioning text and illustrations, and limiting information density.

Keying Text to Illustrations

The mutual reinforcement of text and illustrations can be strengthened by keying the text to the illustration. This can be done by a liberal use of highlights and call-outs, which are "talked to" in the text.

For complicated diagrams, an indexing system can be used. An example of this common technique is shown in figure 6. Three parts of an electrical unit are designated A, B, and C in the picture on the right. These same letters are used in the text on the left to refer to these specific parts. This method can be used with fairly complex diagrams without confusing the reader. The alphabetical or numerical symbols take up little room on the diagram and can be ordered

(for example, clockwise in figure 6) to make it easy to locate any symbol.

Highlights and call-outs help the user zero in on the main items of interest in a picture. A heavy outline or shading or color, together with a callout of the item of interest, can make the text and illustration mutually support each other and help the user relate illustration to text.

Consistent, standard nomenclature should be used in linking text to illustration, and indeed throughout the document. Information becomes less accessible and less understandable if the same item is referred to by different names.

Positioning Text and Illustrations

Because the text and related pictures should work together, they should be positioned close together. Ideally, the user should be able to work back and forth between text and illustration without having to turn a page. While this ideal is sometimes impractical, it is usually possible to keep the illustration close to the relevant text. For important, frequently referenced figures, foldouts are sometimes the answer.

Limiting Information Density

Information is like food. If readers eat too fast, or too much at one time, they get indigestion. If information is presented too fast or in too large doses, readers will get confused. This is because of the limited capacity of short-term memory. Therefore, like food, information must be broken up into "bite-size" pieces to be digestible.

Figure 6: Keying text to illustrations. The mutual reinforcement of text and illustrations (as shown in figure 5) can be strengthened by keying the text to the illustrations through the use of highlights and call-outs which are "talked to" in the text.

148

March 1981 © BYTE Publications Inc

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Good format does this.

Language should be simple and direct. Only words the reader understands should be used, with new words explained as they are introduced. Explanations are easier to read and understand if sentences are short and simple, and if words have few syllables.

Illustrations should not be cluttered with unnecessary information. If they are too "busy," pictures become con

(7a)

fusing and are less useful. To avoid a profusion of details, illustrations can be used in a progression from simple to more complex. This is related to top-down sequencing. An initial overall figure can give the "big picture," which is easy to understand and serves as a beginning structure for proceeding to more detailed illustrations. In forming such progressions, it's important to preserve the relative locations of the parts of

v.

DATA BUS

n

nrai

MEMORY

T>

ADDRESS BUS

CONTROL LINES

0

I )"° Bus

^1/0 BUS

•CONTROL

(7b)

whatever is being pictured. For example, if a simple block diagram of a microprocessor leads off the series, subsequent more detailed diagrams and schematics should show the various parts of the blocks in the same relative positions as the original block. An example is shown in figure 7. Note that the lower detailed diagram preserves the relative positions, established by the upper figure, of the major parts of the system.

Earlier we said that microprocessor literature is suffering from a bad case of "the jargons." However, you'll see by now that there is much more to good documentation than avoiding jargon. You probably have had the experience of reading something and finding that it was very difficult to follow, even though you seemed to understand all the words. In this case, the author managed to avoid technical terminology but failed in other important areas. Good technical documentation requires a highly disciplined approach, and that approach is provided by information design. Those who adopt a go-asyou-please approach may score a success now and then, but it will be by accident. They have no way of knowing whether they have really reached their audience. In many cases they have not.B

RESTART

TSC

RES

til

VMA R/W

IRQ

VMA 02

T^S

A10

All

A12

ROM

CS CS CS CS

AO-9

A7

A8

A9

A10

L2.

R/W

CS

CS

CS

CS

CS

AO-6

ADDRESS BUS

A12

• CSO

A13

« CS1

A1A

RES

PIO

CS2

E R/W

IRQA IRQB

c

^)P0RT A 3 PORT B

Figure 7: To avoid reader confusion, illustrations should be used in a progression from less detail to more. An initial block diagram (7a) can give the overall picture before going into greater detail (7b). When forming these progressions, it's important to keep parts in the same relative positions.

150 March 1981 © BYTE Publications Inc

Circle 85 on inquiry card.

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Programming Quickies

Computing the Determinant of a Matrix

Brian Flynn, 1704 Drewlaine Dr, Vienna VA 22180

Matrix inversion is often used in solving sets of simultaneous equations and in performing multiple linear-regression analysis. But what determines whether or not a matrix can be inverted? The answer is its determinant does. More specifically, if the determinant of a matrix is 0, the matrix is singular and can't be inverted.

A Radio Shack Level II BASIC program for calculating the determinant of a matrix is presented here. The algorithm uses the upper-triangular technique and switches rows, when necessary, to insure that the determinant is always calculated, within the limits of the computing capability of the TRS-80 Model I.

A matrix is a rectangular array of numbers or variables (usually displayed in brackets). A square matrix is twodimensional with as many rows as columns. A characteristic of a square matrix is its determinant. Determinants are defined only for square matrices, just as only square matrices are invertible. Unlike a matrix, a determinant is written as an unbracketed, single number—a lone, lorn creature such as 5, 0.03, or —1. The symbol for a determinant is sometimes det, but more often two parallel vertical lines: | |. (This latter symbol is also used for absolute value. The circumstance in which | | appears determines whether it means absolute value or determinant.)

It's relatively easy to calculate a second-order determinant, that is, the determinant of a second-order (2 by 2) matrix: tally the product of the principal diagonal elements and subtract from this the product of the off diagonal elements. The principal diagonal is the imaginary line segment running from the "northwest" corner to the "southeast" corner of the matrix. The off diagonal, on the other hand, is the one which connects the "northeast" and "southwest" corners. The process of calculating a second-order determinant is illustrated in table 1.

Tallying a third-order (3 by 3) determinant is a bit more difficult than tallying one of the second order. If the elements of the matrix are not too unwieldy, however, the calculation can still be made by hand without much trouble. This is shown in table 2. But for matrices of order four and higher, the business of determining the

°11 a22 - al2°2l

2 • 9-5-3 • 18-15-3

Table 1: The general method for evaluating a 2 by 2 matrix and an example. The elements of the principal or major diagonal are multiplied (aua22), as are the elements of the off or minor diagonal (a12a21). Then the product of the off diagonal is subtracted from the product of the principal diagonal.

' °11 °22033+012023°31 ♦°13°32021

- on o32o23 -012O21O33 -013022031

5 2 4 1 3 7

6 9 9

-5-3- 5-8

9+27-2

7-6 1-9

+ 4-8 -4-3

Table 2: The method for evaluating a third-order determinant is an extension of the method used for second-order determinants. Note that plus signs are associated with the three products formed by solid lines, and minus signs are associated with the three products formed by dashed lines.

152 March 1981 © BYTE Publications Inc

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BYTE March 1981

153

Programming Quickies

determinant can get really complicated. Indeed, calculating a fourth-order determinant one time by hand, using the popular Laplace expansion, is usually sufficient to elicit the plea, "Isn't there an easier way?"

Fortunately, there is. The upper-triangular method is a straightforward, computer-compatible technique for tallying a determinant of any order. The process, illustrated in table 3, is in two steps:

• Transform the matrix so all of the elements below the principal diagonal are Os, using elementary row operations. Anticipate division by 0, and switch rows of the matrix to avoid it.

• Calculate the product of all elements along the transformed principal diagonal. This product is the determinant.

If you ever determine to determine the determinant of a matrix, I hope you find the upper-triangular method useful.!

STEP 1.TRANSFORM THE ELEMENTS OF THE LOWER TRIANGLE INTO

0s: TRANSFORM THE 8 INTO 0 BY MULTIPLYING THE ELEMENTS OF ROW #1 BY-2 THEN ADDING THEM TO THE CORRESPONDING ELEMENTS OF ROW #2.

4 0

©

TRANSFORM THE CIRCLED 2 INTO 0 BY ADDING ROW #1 TO ROW #3.

3

-5 4.5

TRANSFORM THE 8 INTO 0. IF THE ABOVE PATTERN WERE FOLLOWED.-8/0 TIMES ROW #2 WOULD BE ADDED TO ROW #3. TO AVOID DIVISION BY 0, SWITCH ROWS 2 AND3. THIS CHANGES THE ARITHMETIC SIGN OF THE DETERMINANT (LINE 4060 OF THE PROGRAM ).

4.5 -5

STEP 1 IS NOW FINISHED SINCE THE ELEMENTS OF THE LOWER TRIANGLE ARE ALL 0s.

STEP 2. TALLY THE PRODUCT OF ALL ELEMENTS ALONG THE PRINCIPAL DIAGONAL.

DETERMINANT= - [4-8-(-5)] =160

Table 3: The upper-triangular method f or evaluating higherorder determinants consists of two steps: first, transform the elements of the lower triangle into 0s, then find the product of the principal diagonal.

Listing 1: The program for determining the determinant of a matrix.

10 REM CALCULATING THE DETERMINANT OF A

MATRIX

20 REM UPPER TRIANGULAR METHOD

30 REM BRIAN I. FLYNN; FALL 1980

40 REM MOD 1: INITIALIZE & ENTER DATA

50 GOSUB 1000

60 REM MOD 2: CALCULATE DETERMINANT

70 GOSUB 2000

80 REM MOD 3: PRINT DETERMINANT

90 GOSUB 3000

100 GOTO 9999

1000 REM MODULE 1

1010 REM VARIABLES 1020 REM C = USED IN TRANSFORMING

MATRIX 1030 REM DT = DETERMINANT

1040 REM HOLD = USED IN SWITCHING ROWS

1050 REM K = ORDER OF THE MATRIX

1060 REM SIGN = + 1 OR - 1

1070 REM X = MATRIX

1080 REM INITIALIZE

1090 DEFDBL C,D,H,X:SIGN = 1:DT = 1:CLS

1100 PRINT "THIS PROGRAM COMPUTES THE

DETERMINANT OF A MATRIX." 1110 PRINT:INPUT "HOW MANY ROWS (COLUMNS)

ARE IN YOUR MATRIX";K 1120 DIMX(K.K)

1130 REM ENTER DATA 1140 FOR 1=1 TO K

1150 CLS:PRINT "PLEASE ENTER DATA."

1160 PRINF'ROW f';I;":"

1170 FORJ=lTOK

1180 PRINT'OOL r';J:INPUT X(I,I)

1190 NEXT J,I

1200 RETURN

2000 REM MODULE 2

2010 REM CHECK FOR 1ST-ORDER DETERMINANT 2020 IF K= 1 THEN DT = X(l,l):GOTO 2180

2030 REM FILL LOWER TRIANGLE WITH 0 s 2040 FORL=lTOK-l

2050 FORI = LTOK-l

2060 REM AVOID DIVISION BY 0

2070 IF X(L,L) = 0 THEN GOSUB 4000

2080 IF DT = 0 THEN 2180

2090 C = X(I+1,L)/X(L,L)

2100 FORJ=lTOK

2110 X(I+1,J) = X(I+1,J)-X(L,J)*C

2120 NEXT J,I,L

2130 REM TALLY PRODUCT OF PRINCIPAL DIAGONAL

ELEMENTS 2140 FOR 1=1 TO K

2150 DT = DT*X(I, I)

2160 NEXT I

2170 DT = DT-SIGN

2180 RETURN

3000 REM MODULE 3 3010 PRINT"DETERMINANT = ";DT

3020 RETURN

4000 REM SUBROUTINE: SWITCH ROWS 4010 FORM = L+lTOK

4020 IF X(M,L) = 0 THEN 4070

4030 FOR Q = 1 TO K

4040 HOLD = X(L,Q):X(L,Q) = X(M,Q):X(M,Q) = HOLD

4050 NEXT Q

4060 SIGN = -SIGN.-GOTO4100

4070 NEXT M

4080 REM DETERMINANT = 0

4090 DT = 0

4100 RETURN

9999 END

154 March 1981 © BYTE Publications Inc

Languages Forum

A Coding Sheet for FORTH

John O Bumgarner, 17370 Hawkins La Morgan Hill CA 95037

FORTH is a new programming language to most people, and, while it has many advantages over other languages, it does have an unconventional appearance. FORTH is not an intrinsically difficult language, but the unfamiliar appearance, the use of a last-in-first-out stack for parameter passing, and a unique approach to problem solving require you to reorient your thinking a bit.

When I was learning FORTH, I often used to stop and sketch the appearance of the parameter stack as I defined a "word" (portion of a program) to help me get everything in place at the right time. It helped me, the novice FORTH programmer, to have a graphic representation of what the parameter stack looked like at each step. Later, I needed to document programs, so I expanded my sketchy method and made a proper FORTH-style coding sheet that provided the graphic parameter-stack representation.

The need for documentation never

seems to go away, so I still use the

coding sheet regularly.

Now, while I rarely need help visualizing the stack, the need for documentation never seems to go away, and so I still use the coding sheet regularly. It has occurred to me that other FORTH programmers, new or otherwise, would find it useful too.

The coding sheet is shown full-sized in figure 1 and is meant to be copied for use by the reader. The form is deliberately simple to make it as flexible as possible. I have tried to strike a balance between the size of the spaces for words, the size of the spaces for stack items, and the number of stack items.

In actual practice, eight stack items on the form are sufficient because most FORTH words do not manipulate the stack outside of the range of the normal stack operators (which work from three to six words deep). In fact, a rule of thumb for good FORTH programming dictates that, if you get in a situation with the parameter stack that cannot be handled by normal stack operators, you are doing something wrong. You should stop and examine your methods to see how you can avoid the problem. In my experience, this is true; a better way results from a little thought, and it usually is simpler, to boot!

The space for words used in the definition is left a bit wide, as it is common to put short phrases on one line. This not only saves space but also allows frequently used short phrases such as fetching from or storing to a

Text continued on page 162

SUPERBRAIN

ANDCOMPUSTAR

USERS'GROUP

Your users' group is here at last! We are Super • Star International, an independent, world-wide users' group for Intertec Data Systems' SUPERBRAIN* and COMPUSTAR* computers.

Our monthly magazine SUPER •STAR will fulfill all your computing desires. When you join our group, you will enjoy the latest: technical information, tips for beginners, special business uses, equipment reviews, the Intertec story — the people, ideas, and machines behind your computer. In every issue you'll get a free program, industry news, and software reviews.

Plus, we want your programs for our Software Supermarket, where all members can buy programs at affordable prices.

We will investigate all the accessories you have always wanted, test them, and offer them for sale at reduced prices.

With our group buying power we'll give you discounts on commercial software. And that's not all. We'll find group rates for car rentals, hotels, gifts, and more.

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Yearly membership fee is $50.00 U.S., $58.00 Canada, $74.00 Europe and So. America, $81.00 Australia.

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Not affiliated with Intertec Data Systems. 'Superbrain and Compustar are the trademarks of Intertec Data Systems.

March 1981 © BYTE Publications Inc 155

Languages Forum.

DATE

LOCATION

WORD

WRITER

VOCABULARY

STACK

TOP

WORDS

J.O.B.80

Figure 1: A coding sheet for FORTH used to show the effect of words in a FORTH definition on the parameter stack.

156 March 1981 © BYTE Publications Inc

Languages Forum.

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"able 1: An example using the FORTH coding sheet. In this example and that of table 2, FORTH words or phrases are listed in th ightmost column, reading from top to bottom. The stack area on the same line represents zero or more parameters on th arameter stack after the word or phrase has been executed; the rightmost entry in the stack area is always the top-of-stack, wit ntries below it on the stack listed to the left. A dash represents an empty stack. "T/F" represents a flag of either true (nonzer lalue) or false {zero value) pushed to top-of-stack as the result of some comparison operation. Arrows represent the flow of cor rol due to either a loop construct or the outcome of an IF construct. Note that, in the definition of { 7DELETE }, the stack exit he definition with two values on the stack if the comparison made evaluates as false, but only one value if the comparison is trui tee listing 1 for details.

e e h

0

s

y

GET A HEAD START ON TOMORROW WITH THE SOFTWARE THAT'S GOING PLACES. THE UCSDp-SYSTEM:"

JULIE ERW1N, Director of Marketing, SofTech Microsystems

UCSD p-System and UCSD Pascal are trademarks of the Regents of the University of California. LSI11 is a trademark of Digital Equipment Corp.

Our microcomputer software system's going places for good reasons:

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We offer a total development and execution environment, from operating system and cross assemblers to screen editor.

We run on most major microprocessors today: Z80, 8080, 8085, 6502, 6800, 6809, 9900 and LSI-li:M And because the UCSD p-System's portable, you can be sure that what you invest in software today is a good investment in tomorrow.

We're going places and gaining in popularity with microcomputer manufacturers, applications developers, and demanding end users. Get a head start on tomorrow by working with a company that knows how to develop professional quality software, and that's committed to delivering it.

Our system's available for distribution licensing or for single-copy sales. With Pascal, it costs $350... with FORTRAN, $400... and with both languages, $550. Documentation sets are $50. Phone orders are welcome, and Visa and Master Card orders are accepted. Write or call for more details.

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Circle 88 on inquiry card.

BYTE March 1981

157

Why is the 88G Printer the new industry

leader?

QUALITY

The attractive, durable 88G casework is formed from impact-resistant, flameretardant Styron. Microprocessor controlled stepper motors provide precision control over print head and paper positioning. Computer quality tractors position paper for readability and are fully adjustable to accommodate varying paper widths.

MICROPROCESSOR CONTROLLED INTERFACE

The microprocessor array provides the intelligence for a dual RS232 serial and a Centronics® type parallel interface. Both inputs are fully buffered to allow the 88G to receive data and print simultaneously. A IK character buffer is standard with a 2K buffer available as an option.

The short line thruput of the 88G has been increased by incorporation of a Quick Cancel feature that fully utilizes the bidirectional/unidirectional printing capabilities. Built-in diagnostic and self-test capabilities allow the user to easily pinpoint system problems and a Power On confidence test verifies operational status of the printer each time power is applied

VERSATILITY

The 88G prints a full upper and lower case 96 character ASCII set with a crisp, clear 7x7 matrix in 80, 96, or 132 column formats. For text processing and correspondence applications, an 11x7, 80 column serif style matrix can be selected by switch or software command. The dual tractor/pressure-feed paper drive system allows the user to choose either pin-feed, roll, or single sheet papers up to 9.5 inches wide.

Complete forms control allows the 88G to be quickly configured for printing single or multiple-ply invoices, purchase orders, checks, or any type of preprinted form. Optional paper roll holders and single sheet feeders can be quickly attached.

The wide use range of the 88G makes it the perfect companion for business systems, data processing, RO teleprinter and terminal printer applications.

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A high-resolution, dot-addressable graphics option can be added for applications requiring plotting, printing of screen graphics, drawings, illustrations, etc. Single dot print resolution greatly extends the usefulness of the graphics capability. Selection of one of the four horizontal dot densities available customizes the graphic printout, and alphanumerics can easily be included for titling of graphs and illustrations.

LONG LIFE RIBBON CARTRIDGE

Ribbon difficulties are minimized through use of a continuous loop cartridge with a five million character life. It is easily changed without opening the case, and without any complicated or messy threading operations.

PRICE

Every detail is directed toward providing a heavy-duty, commercial quality printer for only $749.00. No other printer on the market today can provide its quality, features and performance at a comparable price. The 88G is an obvious industry leader.

.1 registered trademark of the Centronics IXito Computer Corp.

Micro Peripherals, Inc.

4426 South Century Drive Salt Lake City, Utah 84107 Phone (801) 263-3081

Circle 89 on inquiry card.

Languages Forum.

£? APR. 80

DATE WRITER

i* //.

COUA/TE#_

LOCATION

WORD

VOCABULARY

STACK

TOP

r

iefc?

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u^Utoi

—

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another

one

—

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nte of -V

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WKtH

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niuw

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)

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loop

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WORDS

1 o \/Atf/Afr£E ME6-ATiv/e

o VAfclAljLe NON-WfC

; ^oofj-r&^

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1

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Table 2: Another example using the FORTH coding sheet. See listing 1 for details.

160 March 1981 © BYTE Publications Inc

Solution\s6Jlu-shun\n[ME,fr.MFsfr.L solution-] la: An answer to a problem.

At last there's a microcomputer designed to solve your business' problems? not create new ones. In delivery for close to three years, the MicroDaSys Millie™ is a proven hardware design that now comes with the fantastic SoftwareHows™ DBI Accounting Solutionware™you've seen advertised -- a $2500 dollar value alone! This is one computer that's complete when you buy it, right down to the best applications software available. There are no "required options". And we've got all the best features: Z-80, 64K, CP/M1 , dual double density 8" floppies for 1MB on line storage, 82x24 CRT with special features, IBM format keyboard with numeric pad, NEC 55cps letter quality printer, S-100 bus. Also, Millie is supported by a nationwide rep network and one of the best service contracts in the iDusiness. And Millie is price competitive with much smaller computers. Why settle for less than the best? Call or write today for flyers and manuals. You'll be glad you did.

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Rgq.tm, Digital Research

Languages Forum.

Listing 1: A block of FORTH code. The FORTH words EXPECT sheets in tables 1 and 2.

7DELETE ] , and COUNTER are explained on the coding

0 ( Character and data input words) 1

2 ( EXPECT accepts n ch's putting them at given address)

3 ( Use: address n EXPECT )

4 : EXPECT 0 DO KEY OVER I + C! LOOP DROP ;

5 HEX ( change base to HEX for the following word)

6 ( 7DELETE returns only T if given ch. is a DEL )

7 ( otherwise it returns the given ch. and a F on the top)

8 : 7DELETE 7F OVER = DUP IF SWAP DROP THEN ;

9 DECIMAL

10 0 VARIABLE NEGATIVE 0 VARIABLE NON-NEG

11 ( COUNTER counts the number of negative and non-negative)

12 ( numbers and exits if given a zero. FETCH supplies §'s)

13 : COUNTER 0 NEGATIVE ! 0 NON-NEG ! BEGIN

14 FETCH DUP 0 < IF 1 NEGATIVE +! ELSE 1 NON-NEG +!

15 THEN 0= UNTIL ;

Text continued from page 155:

variable to read better. Such condensed definitions are also useful to keep as documentation. (See table 2.)

[Editor's note: I have used John's sheet and found it very helpful in the design and documentation of FORTH words. I like to indent my entries in the "WORDS" column to show if...then...else constructs and loops. I have also been working with a similar diagram that allows a line to run across the long dimension on a page; this gives me more room for indenting FORTH words and documenting what they do....GW]

Listing 1 is an example of a typical FORTH block of code. If it were part of a bigger listing, there would be

three such blocks on one page and the page would be called a triad. If you wanted to see this block or edit it at your terminal, you would type { 123 LIST }. [The braces are not part of the FORTH phrase, but are the standard BYTE delimiters that isolate FORTH words that include punctuation and FORTH phrases from the surrounding text. ...GW]

The FORTH coding sheets show the detailed structure of each of the three words defined in block 123. The coding sheets in tables 1 and 2 show the words in great detail.

I hope that this coding sheet is of use to fellow FORTH enthusiasts. It certainly helped me learn FORTH, and allows me to produce clear documentation. ■

?? Micros aren't just for games anymore.. AARDVARK gets down to brass TAX.**

AARDVARK SOFTWARE takes home computer use one practical step further with "Personal Tax," a federal income tax program designed specifically for horfie use.

"Personal Tax" was developed by CPA's and computer professionals. It will calculate Federal Forms 1040 and 4726, as well as schedules A, B, G and TC. The program features multiple entries for a variety of inputs (e.g. wages, dividends and charitable contributions). An indexed instruction manual and easy-to-follow input forms are included.

"Personal Tax" computes quickly and accurately, then displays or prints the totals automatically (using a standard printer inter

face). You simply copy the totals onto your IRS forms.

This spring, use your microcomputer to simplify your taxes and file with confidence! You won't have to spend half of your refund either. The "Personal Tax" program is very affordable at only $75.

"Personal Tax" will run on: Apple ll,TRS-80 Models I and II, and OSI. Additionally, under CP/M, the program will run on VectorGraphics, North Star and Cromemco.

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AARDVARK SOFTWARE IIMC

The Microcomputer Peoplefor Professionals

783 NORTH WATER STREET MILWAUKEE WISCONSIN 53202 414/289-9988

162

March 1981 © BYTE Publications lnc

Circle 91 on inquiry card.

EXCITING NEWS FOR INVESTORS WITH TRS-80 32K DISK-BASED SYSTEMS!

Standard & Poor's proudly announces

STOCKPAK, a unique software and data system

to help you meet your investment goals like a Wall Street professional.

STOCKPAK not only delivers a "stand-alone" Portfolio Management System but also gives you the software for Standard &. Poor's monthly Common Stock Data Service (available to TRS-80 owners on a subscription basis). With STOCKPAK and the Data Service you command one of the most powerful and versatile investment tools available.

Here's How STOCKPAK Will Help You:

A 900 COMPANY DATA BASE SERVICE

Monthly Data Service subscribers receive a diskette containing 30 vital financial items on 900 of the most widely traded stocks (S&P "500" and 400 NYSE, ASE and OTC issues). Accompanying this monthly diskette is an Investor's Newsletter highlighting important financial news and investment strategies, with suggestions for maximizing the usefulness of the system.

STOCKPAK SELECTION SYSTEM

The heart of STOCKPAK is a powerful, analytical stock selection tool which enables investors to choose stocks which meet their investment criteria. For example, you may wish to select only those oil and gas stocks with price/earnings ratios of less than 7 and yields of 6% or more. Once a group of stocks has been selected, you can store it as a separate data file for continuing use.

PORTFOLIO MANAGEMENT SYSTEM

REPORT WRITER

You can define the report formats you would like to see on those stocks meeting your investment objectives. Hundreds of calculations and ratios that you define can be sorted, averaged or totalled, and displayed on video screen or optional printer.

Now you can effectively evaluate and manage your own stock portfolio of up to 100 securities with as many as 30 transactions for each. You can record "buy" and "sell" transactions, price and dividend information and stock splits for instant retrieval, for record keeping and tax purposes. You can measure actual performance or create hypothetical situations to help you make "buy" or "sell" decisions.

HOW TO ORDER STOCKPAK

STOCKPAK is designed exclusively for TRS-80 users with 32K business systems with two mini-disk drives. You can obtain the basic software and sample Data Base, plus a comprehensive User's Manual from your local Radio Shack Store for only $49.95. The STOCKPAK Monthly Data Updating Service can be ordered directly from Standard & Poor's for $200 annually, or from the order form provided in the basic package you purchase from Radio Shack.

s/i

Standard & Poor's Corporation

25 BROADWAY, NEW YORK, NY 10004 (212) 248-3994/3374

Circle 92 on Inquiry card.

BYTE March 1981 163

BYTE's Bits

IEEE Committee Studies Terminals

Today's computer terminals talk, walk, listen, feel, and see. Terminal technology embraces the sciences of computers, electronics, human factors, acoustics, optics, and mechanics. The Communications Society of the IEEE (Institute of Electrical and Electronics

Engineers) has formed a Terminals Committee to focus on the science of communications terminals. The committee will complement the data-communications, computer-communications, and transmission-systems committees' activities by sponsoring workshops on special topics and by writing standards.

Technological advances have added video and game

terminals, and robots, to the ranks of terminal devices. Other areas of interest are the telecommunications networks for voice and data plus long-distance private networks, local area networks, instrumentation, and data bases. Terminals can be electrically, acoustically, or optically connected to these networks.

The first sessions sponsored by the Terminals

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Committee will be held at the 1981 International Communications Conference this June. Papers will be read on recent advances in terminals and the impact of communications systems on terminals. Topics being considered for the 1981 and 1982 workshops include office-automation terminals, graphics communications, plus speech-processing and game terminals. For more information, contact Fritz Froehlich, Bell Laboratories, Rm 1D622, Holmdel NJ 07733, (201) 949-4990.

Computer Camp

If your child is between the ages of 10 and 18, he or she can spend part of this summer learning about computers and programming and still enjoy summer camp activities. The National Computer Camp will be held in Moodus, Connecticut, July 19 thru 24 and July 26 thru 31. Children at all levels of computer experience are invited. Contact Michael Zabinski, 382 Hitching Post Dr, Orange CT 06477, (203) 795-9069.

TEXNET—Network for TI-99/4 Users

Texas Instruments and Source Telecomputing Corporation have developed a home-information and communications service for TI-99/4 users. TEXNET is a subscription service available over telephone lines coupled to the home computer through a modem. It offers the services of The Source information utility plus a text-to-speech capability, which allows users to hear messages typed on the keyboard or transmitted over the TEXNET system. For more information on TEXNET and the TI-99/4 computer, contact Texas Instruments Inc, Consumer Relations, POB 53, Lubbock TX 79408, (800) 858-4565; in Texas (800) 858-4279. ■

164 March 1981 © BYTE Publications Inc

Circle 93 on inquiry card.

This

printer

costs less

than $450.

Beat that...

if you can.

Epson

This is the Epson MX-70. The lowest priced dot matrix printer you can buy. Now, that in itself should make it very attractive to a lot of people. But you ain't heard the half of it.

To begin with, the MX-70 has a lot more in common with our now-famous MX-80 than just the name. Like unequalled Epson reliability. And technological breakthroughs like the world's first disposable print head. But frankly, the MX-80 packs a lot more power than some people need. So we built the MX-70 to be a no-frills printer. At a no-frills price.

But the MX-70 is still a great little printer. We give you 80CPS unidirectional printing. Top-of-form recognition. Programmable line feed and form lengths. Plain paper printing. An easy-to-read 5x7 matrix. Self test. And an adjustable tractor feed.

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So now you've got a choice. You want more power and extra functions, you buy the MX-80. You want a basic little printer that prints, and keeps on printing, you buy the MX-70. They're both at your dealer now.

But at this price, you'd better hurry.

EPSON

EPSON AMERICA, INC.

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Circle 94 on inquiry card.

BYTE March 1981

165

A Beginner's Guide to Spectral Analysis, Part 2

Mark Zimmermann

9410 Woodland Dr

Silver Spring MD 20910

In Part 1 of this article, I introduced some of the ideas behind the Fourier transform in one dimension. Here, I will try to extend those ideas to twodimensional space. I will introduce a few of the many uses of two-dimensional spectral analysis, with particular emphasis on image processing. The main computer program that accompanies this article (see listing 1) is a 6502 assembly-language program that performs a two-dimensional transformation on a 25- by 40-pixel image. The program is specifically adapted to run on the Commodore PET microcomputer with 8 K bytes of programmable memory, but it should be a reasonably straightforward process to modify the code to work on other comparable machines. Several floating-point arithmetic routines are used from the PET's BASIC ROM (read-only memory); a table is included that describes what each routine does, so that it may be replaced by your own arithmetical procedures if necessary.

Components of Waves

As you will recall, the whole notion of Fourier, or spectral, analysis is to take a signal that is, for example, a function of time, and resolve it into its components (ie: the various frequencies that make up the whole). A chord played on a piano may produce a sound that is very complicated when plotted on an oscilloscope screen, but when the chord is Fourier analyzed, the individual notes (component frequencies) stand out.

It is mathematically possible to express any reasonable function as a sum of sines and cosines of various frequencies. The mathematical recipe for finding how much of each sine and cosine went into making the original signal is a fairly simple process that is discussed in many books (see references on page 198). Instead of going into the math here, however, I'd rather discuss the "feel" of Fourier transforming, with the objective of helping you develop some instincts about what a transform should look like and what it means.

Any reasonable

function may be

expressed as a sum of

sines and cosines of

various frequencies.

Figure 1 on page 168 shows several pairs of graphs. In each pair, the graph on the left represents a function of time. It could be showing, for instance, the difference between normal atmospheric pressure and the instantaneous pressure in a passing sound wave.

The graph on the right shows the Fourier transform (a function of frequency) of the graph on the left. It plots the amount of the components needed at each frequency to make the left-hand graph. The amount of sine wave is shown as a dashed line; the

amount of cosine wave is a solid line. The horizontal axis runs from zero frequency (where it's intercepted by the vertical axis) to high frequencies. If the amount graphed on the right goes negative, it simply means that the original signal needs to have some amount of the function —sine or — cosine added to it. In other words, the original signal contained some sine waves that were 180° out-ofphase with the standard sine wave (so there's nothing special or mysterious about having a negative amount of a given frequency component).

What kind of insights can you get by examining the graphs in figure 1? First, it's clear that any function of time which is symmetric with respect to the t = 0 (vertical) axis is made up only of cosine waves, and any function that is asymmetric with respect to t = 0 is made of only sines. Every cosine wave is symmetric about the origin of time, so a sum of cosines should certainly be symmetric; every sine wave is asymmetric. A function that is neither perfectly symmetric nor perfectly asymmetric requires both sines and cosines in its constituent frequencies.

A second fact which becomes apparent from a study of figure 1 is that functions of time which have some net area (area between the curve and the horizontal axis) always have some amount of component with zero frequency plotted in their transforms. A zero-frequency wave doesn't wave at all; it's a constant number as time goes by, like cosine(O). Contrariwise,

166 March 1981 © BYTE Publications Inc

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BYTE March 1981

(la)

(lb)

t-0 TIME—*

(le)

UO TIME—*

(lg)^

/

A

t

0

TIME

\ /

FREQUENCY »

Figure 1: Graphs on the right (functions of frequency) plot Fourier transforms for the specific functions on the left (functions of time), indicating the amount of each component frequency present in the original. Abrupt changes with respect to time (figures la thru Id) are reflected in the transforms by the presence of higher-frequency energy. Graphs of functions exhibiting periodicity (figures le thru Ih) produce peaks centered on the frequency of this oscillation in the associated transform.

if a function of time has no net area, if it is positive just as much as it is negative, then its Fourier transform has no zero-frequency component. This component, in fact, is just the average value of that signal.

Let's examine several specific pairs of graphs. The transform of a square pulse (figure la) contains a number of low-frequency cosines (to build up the area under the pulse and create the flat-topped sections which obviously change little with time), but in addition, a fair amount of highfrequency cosine energy is required to make the square pulse. A triangular pulse of the same area has similar low-frequency requirements, but needs fewer higher-frequency waves (see figure lb). A Gaussian (bellshaped) curve requires very little high-frequency contribution to make its smooth function of time (see figure lc).

This correlation between "abruptness" and high frequencies in the Fourier transform is, in fact, quite general. Functions that change abruptly with time, like the square wave, or that have a lot of fine detail (the sharp edges), are not composed only of low-frequency, slowly changing waves; the jumps require a lot of high frequencies to define them. As a square wave becomes narrower and narrower, more and more high frequencies are necessary: a falling body's thud, if replayed at a high enough speed, can sound like an abrupt gunshot. Signals that don't have sudden jumps, like those represented in the triangular graph, can be made using fewer highfrequency components, but the sharp corners where the slope of the triangle's sides changes still require high-frequency sinusoids. Smooth curves like the Gaussian, where there isn't much detail, require the least amount of high frequencies.

Finally, look at the graphs in figures le thru lh. The functions of time (on the left) all show some sort of periodic behavior. Their transforms all reveal this by a peak at or near the frequency of oscillation. The more cycles of oscillation that the temporal function goes through, the sharper the peak in frequency space. This effect is not just mathematical—you can hear it. A heavily damped bell that rings for very few cycles produces an abrupt note

168 March 1981 © BYTE Publications Inc

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BYTE March 1981 169

Listing 1: The 6502 machine-language program 2DFT performs two-dimensional Fourier transform of images on the Commodore PET's video display. SINTAB is a table of sin (x) for x = 0, it/20, 2ir/20,..., thru 19ir/20, in PET floating-point notation (5 bytes per number). Numbers may be scaled up or down for normalization; one good choice is to divide each sine by the square root of 32. ROWSXFRMD is a table of transformed rows from the screen, beginning with row 0, frequency 0, real (cosine) transform, then row 0, frequency 0, imaginary (sine) transform, then row 0, frequency 1, real transform, then imaginary, and so on, ending with row 24, frequency 20, imaginary transform.

;enter here to transform rows of screen data ;do 24+1 rows (all of them)

;point to bottom row pf screen

.point to bottom of answer area for storage

:DONE = RTS instruction, to return to BASIC control

DOROWS:

LDA

#18

STA

ROWCOUNT

LDA

#C0

STA

ROWO

LDA

#83

STA

R0W0+1

LDA

#FB

STA

ANSO

LDA

#1F

STA

ANSO+1

L00P1:

JSR

ROWTRANSFORM

DEC

ROWCOUNT

BMI

DONE

SEC

LDA

ROWO

SBC

ins

STA

ROWO

BCS

OVER1

DEC

ROWO+1

0VER1:

JMP

LOOP1

DONE:

RTS

ROWTRANSFORM:

LDA

#64

L00P2:

STA

FREQ

LDA

#C3

STA

POINT

JSR

ONEFREQ

JSR

STOREIT

LDA

#91

STA

POINT

JSR

ONEFREQ

JSR

STOREIT

LDA

FREQ

SEC

SBC

#5

BPL

L00P2

RTS

STORE IT:

LDX

ANSO

LDY

ANSO+1

JSR

DAA6

LDA

ANSO

SEC

SBC

#5

STA

ANSO

BCS

OVER2

DEC

ANSO+1

OVER 2:

RTS

ONEFREQ:

LDA

#27

STA

COLNUM

LDX

#5

LDA

#0

L00P3:

STA DEX

MYACC-l.X

BNE

LOOP3

TOP:

LDY

COLNUM

LDA

(ROWO),Y

TAY

LDA

#0

JSR

D278

LDY

#STABPG

LDA

POINT

JSR

D8FD

LDY

#0

LDA

#MYACC

JSR

D73C

LDY

#0

LDX

#MYACC

JSR

DAA6

DEC

COLNUM

BMI

DONE

LDA

POINT

SEC

SBC

FREQ

BCS

OVER3

ADC

#C8

0VER3:

STA

POINT

JMP

TOP

;back up to prior row (40 elements/row)

;number in FREQ is 5 times frequency (5 bytes/number) ; initially set to maximum frequency...count down to 0

,set pointer for sine (imaginary part) transform

;set pointer for cosine (real) transform

;decrement frequency being analyzed for ;do all frequencies 0-20 inclusive

;setup for PET utility subroutine ;store P at X+256Y

;move answer pointer back to a free space

;set column counter to maximum = 39

;MYACC is 5 adjacent page zero.locations ;clear them out here

;get screen character at current row & column

;convert integer 256A+Y to floating in P

;point to page of sine table

,256STABPG+POINT points to a sine to be multiplied in

;(sine)*P is calculated and stored in P

;point to MYACC, my accumulator's 5 bytes ;(MYACC)+P is put into P

;(P) gets rounded & transferred to 256Y+X (my ace.) :quit when all columns done

;move pointer a distance FREQ through table ;work modulo 200, to stay on table

Listing 1 continued on page 174

without a well-defined musical pitch. A tuning fork that rings for thousands of cycles makes a clear, precise tone.

Contemplation of some graphs of Fourier-transform function-pairs can lead to a number of other useful insights. The illustrations in figure 1 were adapted from Ron Bracewell's excellent book, The Fourier Transform and Its Applications (see references), which is worth looking at for further inspiration.

Adding a Dimension

Many signals, like sound, or light from a star, are essentially one-dimensional, and the techniques discussed above and in the earlier part of this article are immediately applicable to them. But there are other, extremely interesting signals which are two, three, or more dimensional when they arrive. Rather simple extensions of the concepts involved in one-dimensional spectral analysis will allow multidimensional signals to be transformed, analyzed, and manipulated. Ill discuss the two-dimensional case because problems with more dimensions can be attacked by completely analogous methods.

What function does a two-dimensional Fourier transform serve? For one thing, it can help solve many three-dimensional problems which have translational symmetry; that is, problems in which one of the three spatial dimensions can be trivially factored out. An obvious example is a system like a coaxial cable, or a cylindrical waveguide, where everything looks the same as you move along the length of the device. Two-dimensional Fourier transforms can give the electrical characteristics of such systems. To some extent, problems involving thin layers like the Earth's atmosphere can be dealt with using two-dimensional transforms.

If that were all, a few people might play around with two-dimensional spectral analysis, but it wouldn't be a huge industry. However, there's another class of problems that are of overpowering interest. These problems are in the field of imaging, or remote sensing. Ever since evolution came up with the first rudimentary eye-spots, creatures have been using electromagnetic radiation to probe their environments. With the development of lenses that form a two

Text continued on page 178

170

March 19B1 © BYTE Publications lnc

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APPLE II or APPLE II PLUS, 16K min $239.00 (#19-85)

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174 March 1981 © BYTE Publications lnc

Listing 1 continued:

D0C0LS: LDA

#14

STA

C0LNUM

L00P4: LDA

#3C

STA

FREQ

JSR

FTC6.D

DEC

COLNUM

BPL

L00P4

RTS

FTC&D: LDA

COLNUM

CLC

ADC

#D3

STA

RDISP

LDA

#83

STA

RDISP+1

LDA

#13

SEC

SBC

COLNUM

STA

LDISP

LDA

#80

STA

LDISP+1

LDA

COLNUM

ASL

A

STA

ADRS

ASL

A

ASL

A

ADC

ADRS

ADC

#2E

STA

STASH

LOOP 5: STA

ADRS

LDA

#1F

STA

ADRS+1

LDA

#91

STA

POINT

JSR

COLXFRM

LDX

#5

L00P6: LDA

MYACC-l.X

STA

C0SACC-1.X

DEX

BNE

L00P6

LDA

#1F

STA

ADRS+1

LDA

STASH

CLC

ADC

#5

STA

ADRS

LDA

#C3

STA

POINT

JSR

COLXFRM

LDY

m

LDA

It COSACC

JSR

D95E

JSR

D728

JSR

DADE

LDA

#0

STA

SGNCOMPR

LDA

B0

JSR

D900

LDY

#0

LDX

# COSACC

JSR

DAA6

LDA

#LF

STA

ADRS+1

LDA

STASH

STA

ADRS

LDA

#C3

STA

POINT

JSR

COLXFRM

LDX

#5

1.00P7: LDA

MYACC-l.X

STA

SINACC-1,X

DEX

HNF.

LOOP 7

LDA

#1F

STA

ADRS+1

LDA

STASH

CLC

ADC

#5

STA

ADRS

LDA

#91

STA

POINT

JSR

COLXFRM

LDY

ItO

LDA

if SINACC

JSR

D73C

JSR

DADE

LDA

#0

STA

SGNCOMPR

;enter here to transform and display 20';2 columns

j60/5 = 12 is maximum frequency which can be shown ;begin at 12 and do frequencies through -12 ;fourier transform column &. display

;when finished, go back to BASIC control

jpoint to screen address of right-hand column to ;be displayed (zero at center)

;point to left-hand display column

;(column 20 is only displayed on right...see below)

;temporary storage for multiplication 10*C0LNUM

;now we have 10-C0LNUM

;and now accumulator points to low byte of the real

;part of the last R0WSXFRMD table entry for this column

;high part of end of R0WSXFRMD table address in 8K PET

;pointer set for cosine transform of real part of data ireturns answer in MYACC and in P

; transfer answer to COSACC on page zero, 5 bytes

;reset data pointer before doing sine transform ;stash holds result of low byte address calculation

;add 5 to get to point to imaginary part of data ;there is never a carry

;point setup for sine transform of imag. data

;transfer COSACC to S

;calculate S-P and leave result in P

;copy P to S

;set sign comparison (address BE) to + ;must call PET subroutine with (B0) in A ;(P)*(S)=(P)**2 is calculated and left in P

;transfer P to COSACC

jpoint to real data again

;setup for sine transform of real data

; transfer answer to SINACC on page zero

jpoint to imaginary data ;and do cosine transform

;add (SINACC) -+-(P) and store in P ;copy P to S

Listing 1 continued on page 176 Circle 101 on inquiry card. »

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Listing 1 continued:

LDA

BO

JSR

D900

LDY

#0

LDA

#COSACC

JSR

D73C

JSR

DE24

LDA

BO

CMP

#89

BCS

LIMITER

JSR

D0A7

LDA

BA

JMP

OVERLTD

LIMITER:

LDA

#FF

OVERLTD:

LDY

#0

STA

(RDISP),Y

TAX

LDA

RDISP

SEC

SBC

#28

STA

RDISP

BCS

0VER4

DEC

RDISP+1

0VER4:

LDA

COLNUH

CMP

#14

BEQ

0VER5

TXA

STA

(LDISP),Y

LDA

LDISP

CLC

ADC

#28

STA

LDISP

BCC

0VER5

INC

LDISP+1

0VER5:

LDA

FREQ

CMP

#C4

BEQ

D0NE2

SEC

SBC

#5

STA

FREQ

LDA

STASH

JMP

LOOP b

D0NE2:

RTS

COLXFRM:

LDA

m

LDX

lib

LOOPS:

STA DEX

MYACC-1,X

BNE

L00P8

LDA

#19

STA

ROWNIJM

L00P9:

LDY

ADRS+1

LDA

ADRS

JSR

DA74

LDY

#STABPG

LDA

POINT

JSR

D8FD

LDY

#0

LDA

#MYACC

JSR

D73C

LDY

#0

LDX

t'MYACC

JSR

DAA6

DEC

ROWNUM

BEQ

DONE2

LDA

POINT

SEC

LDX

FREQ

BMI

NECFREQ

SBC

FREQ

BCS

0VER6

ADC

#C8

0VER6:

STA

POINT

JMP

NXTADR

NECFREQ:

SBC

#C8

CMP

FREQ

BCC

OVER7

SBC

FREQ

JMP

0VER6

0VER7:

LDA

SEC

POINT

SBC

FREQ

JbS

0VER6

NXTADR:

■ LDA SEC

ADRS

SBC

#D2

STA

ADRS

BCS

0VER8

DEC

ADRS+1

0VER8:

JMP

L00P9

;square of P is now in P

;(C0SACC)+(P) is in P

;SQR(P)...now we have fourier amplitude to be plotted!

;must avoid overflow, so check exponent of answer

; take branch if result is bigger than 255 ;convert P to an integer in B3,B4 ;but B3 is zero, by limiting process

^replace overflow by 255

;display it on the screen! ! --£ ir s t, right column

^subtract 40 to point to previous row

;check column number, and don't plot column ;number 20 (no room on screen!)

;plot result in left column here

;add 40 for next row

;see if we've reached frequency of -12 yet...

^decrement frequency

; go back and do it again at new frequency

;clear out MYACC's 5 bytes

;initialize counter of rows

;'transfer column member pointed to by ADRS to P ;point to sine table page

; (sine)1'? in P

; (MYACC)-f(P) in P

; (P) to MYACC

;return when all 25 are done

:musr. handle movement of pointer carefully ;work modulo 200, stay in table

; for FREQ less than zero, this section ;moves pointer while staying within table

;back up 210 to previous column member

176 March 1981 © BYTE Publications Inc

SHORTEN THE JOURNEY TO KNOWLEDGE.

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BYTE March 1981

177

Circle 104 on inquiry card.

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Text continued from page 170:

dimensional image on the retina, remote sensing took a giant step forward.

When conditions are good, the images that develop on photographic plates or inside vidicons (televisioncamera tubes) can be used just as they are. But often, noise or other interference makes the original image low-quality. When astronomers look up, or spy satellites look down, they want to squeeze every possible bit of information out of their sensors, to "milk" every photon. That's one major reason for all the progress in image analysis and two-dimensional signal processing that has been made in the past few decades.

Advantages of transforming a visual image into the frequency domain overcome all the limitations of the photographic medium.

The advantages of transforming a picture into the frequency domain, where the elemenfs of the image that vary periodically are gathered and grouped together, are numerous, just as were the advantages of analyzing a one-dimensional signal in frequency space (as discussed last month in Part 1). By working digitally inside a computer, you overcome all the limitations of the photographic medium. It's easy to enhance or mute contrasts, to intensify edges of objects (high1 spatial frequencies) or to take out distracting large-scale brightness variations (low-spatial frequencies). The wonderful images that come back from NASA's planetary probes are automatically processed by these kinds of techniques before anyone sees them.

If, after all this build-up, you're expecting to hear that the two-dimensional Fourier transform is an arcane, incomprehensible mathematical process, I'm sorry, but I have to disappoint you. To take a two-dimensional transform, you merely need to choose a pair of perpendicular coordinate axes (x and y). First do a onedimensional Fourier transform in the

x direction, and then do a onedimensional transform on the result of that, in the y direction. That's ail there is to it!

The 2DFT Program

The 6502 assembly-language program in listing 1 performs two-dimensional Fourier transforms. The program takes as its input data the contents of the Commodore PET microcomputer's video-display screen: 1000 numbers, arranged in 25 rows of 40 integers, each one in the range 0 thru 255. The results of the transformation are displayed on the screen. Only the amplitude of the transform is shown; all phase information (whether the wave is sine, cosine, or a mixture) is suppressed.

I'd like to take a little time now to describe how the program works, and the choices and compromises I had to make in implementing it. This discussion should help you if you need to adapt 2DFT to run on a different microcomputer, and it should also be a useful starting point for modifications and improvements of my program. After the discussion, 111 return to the uses of the program, the insights that you can achieve by playing around with it, and the fascinating topic of holography, and how to do it with this program.

First, concerning the fundamental algorithm used to do the transforms: as mentioned above, a true two-dimensional Fourier transform results after you perform separate onedimensional transformations on each row of a matrix, and then perform separate one-dimensional transformations on each resulting column of data. 2DFT does that. The routine DOROWS finds the amount of cosine phase necessary at each frequency, as well as the amount of sine. Those numbers are stored in memory for each row. Then, the routine DOCOLS does the same thing for each column of stored half-transformed data, and puts the amplitude of each resulting frequency-space point onto the screen. The amplitude is simply the square root of the sum of the squares of the cosine component and the sine component (like finding the hypotenuse of a right triangle).

To do the one-dimensional row and column transformations, DOROWS and DOCOLS call subroutines ROWTRANSFORM and COL

178 March 1981 © BYTE Publications Inc

Software for the Apple II and Apple II Plus*

ASTEROIDS IN SPACE"

By Bruce Wallace

An exciting space action game! Your space ship is traveling in the middle of a shower of asteroids. Blast the asteroids with lasers, but beware — big asteroids fragment into small asteroids! The Apple game paddles allow you to rotate your space ship, fire its laser gun, and give it thrust to propel it through endless space. From time to time you will encounter an alien space ship whose mission is to destroy you, so you'd better destroy it first! High resolution graphics and sound effects add to the arcade like excitement that this program generates. Runs on any Apple II with at least 32K of RAM and one disk drive.

On Diskette - $19.95

Cassette

FASTGAMMON" By Bob Christiansen. Sound, hi res, color, and musical cartoons have helped make this the most popular backgammon playing game for the Apple II. But don't let these entertaining features fool you — FASTGAMMON plays serious backgammon. Runs on any Apple II with at least 24K of RAM. $19.95 Diskette - $24.95

ASTROAPPLE'" by Bob Male. Your Apple computer becomes your astrologer, generating horoscopes and forecasts based on the computed positions of the heavenly bodies. This program offers a delightful and stimulating way to entertain friends. ASTROAPPLE produces natal horoscopes (birth charts) for each person based on his or her birth data. Any two people may be compared for physical, emotional, and intellectual compatibility. The program is written in Applesoft BASIC with machine language subroutines. It requires either RAM or ROM Applesoft and at least 32K of memory.

Cassette - $14.95 Diskette

$19.95

SSpfe FRACAS" by Stuart Smith.

A fantastic adventure game like no other! Up to eight players can participate in FRACAS at the same time. Journey in the land of FAROPH, searching for hidden treasure while warding off all sorts of unfriendly and dangerous creatures. You and your friends can compete with each other or you can join forces and gang up on the monsters. Your location is presented graphically and sound effects enliven the battles. Save your adventure on diskette or cassette and continue it at some other time. Both integer BASIC and Applesoft versions included. Requires at least 32K of RAM.

Cassette-$19.95 Diskette - $24.95

BENEATH APPLE MANOR'" by Don Worth. Descend beneath Apple Manor into an underground maze of corridors, rooms, and secret passages in quest of rich and powerful treasures. The dungeon complex consists of many floors, each lower level more dangerous than the last. If you can reach the lowest level, you may even find the ultimate object of your quest, the fabled golden apple of Apple Manor. Strategy is extremely important as you deal with a variety of monsters, each with its own characteristics. Written in integer BASIC with machine language subroutines. Requires integer BASIC and at least 16K of RAM on cassette or 32K of RAM on diskette.

Cassette - $14.95 Diskette

$19.95

BATTLESHIP COMMANDER" by Erik Kilk and Matthew Jew.

A game of strategy. You and the computer each start out by positioning five ships of different sizes on a ten by ten grid. Then the shooting starts. Place your volleys skillfully — a combination of logic and luck are required to beat the computer. Cartoons show the ships sinking and announce the winner. Sound effects and flashing lights also add to the enioyment of the game. Both Applesoft and integer BASIC versions a re included. Requires at least 32K of RAM.

Cassette - $14.95 Diskette - $19.95

BABBLE" by Don Worth. Have fun with this unique software. You write a story, entering it as a BABBLE program. As you write the story you specify certain words to be selected by the computer or entered from the keyboard at execution time. Run the program and watch BABBLE convert your story into an often hilarious collection of incongruities. The ways in which BABBLE can entertain you are limited only to your imagination. You can compose an impressive political speech or write poetry. You can plan a dinner menu. You can even form images on the screen or compose musical tunes with the help of BABBLE. The cassette version requires at least 16K of RAM and the diskette version requires at least 32K of RAM. BABBLE is written in machine language and runs on any Apple II computer.

Cassette - $19.95 Diskette

My SISTER'S pencil anftp,pE.NCR LOVES YOUR ANTEATER, AND THE CP.ABGRASS IS ATTACKING THE FRIENDLY1 MATADOR.

BABBLE

$24.95

LINKER by Don Worth.

Turn your Apple II or Apple II Plus into a powerful and productive software development machine with this superb linking loader/editor package. LINKER does the following and much more:

• Dynamically loads and relocates suitably prepared machine language programs anywhere in RAM.

• Combines a main program with subroutines. You can assemble a subroutine once and then use it with as many main programs as you wish.

• Produces a map of all loaded routines, giving their location and the total length of the resulting module.

• Contains a library of subroutines including binary multiplication and division, print text strings, delay, tone generator, and random number generator.

Linker works with virtually any assembler for the Apple II. Requires 32K of RAM and one disk drive.

Diskette - $49.95 Manual Only - $19.95

QUflLny SOFTW71R6

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Now exclusive distributors for products from The Software Factory, Newhall, California *Apple II and Apple II Plus are trademarks of Apple Computer. Inc

WHERE TO GET IT: Call us at (213) 344-6599 forthe name of the Quality Software dealer nearest you. If necessary you may order directly from us. Mastercard and Visa cardholders may place orders by telephone. Or mail your check or bankcard number to Quality Software, 6660 Reseda Blvd., Suite 105, Reseda, CA 91335. California residents add 6% sales tax. SHIPPING CHARGES: Within North America orders must include $1.50 for first class shipping and handling. Outside North America the charge for airmail shipping and handling is $5.00. Pay in U.S. currency.

Circle 105 on inquiry card.

BYTE March 1981

179

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BYTE March 1981 181

XFRM, respectively. These simply use the old, classical, straightforward method of calculating a Fourier transform—no fast-Fourier-transform subtleties!

I've avoided talking about the mathematical mechanism for moving from ordinary space to the frequency domain in these articles so far, because there are ample technical references which explain such matters in great detail, and because the calculation tends to get in the way of the real substance of the subject, especially in an introduction such as this one. Here, let me just say that the transforms are accomplished by multiply

ing each row (or column) element by a sinusoidally varying factor, and adding up the results of those multiplications at each frequency. To find out how much cosine phase at frequency / is in a given row, multiply each row element r(x) by cos(27r/;c) and sum those products for the whole length of the row. The amount of sine wave is found by multiplying r(x) by sin(27r/;c) and summing those results. You can unite the cosines and sines into a set of complex numbers, with the cosines making the real parts and the sines the imaginary parts. Then, usual complex-number algebra helps keep track of how to add and subtract

S

B8 B9 BA BB BC BD BE BF

P

BO B1 B2 B3 B4 B5

Contents exponent + 80 fractions MSB frac. byte 2 frac. byte 3 fraction LSB. sign

sign comparison roundoff byte

S = e 82 AD

F8 54 59 00 FF 00

P= -ir/2 81 C9 OF DA A2 FF

Note: +,-,*,/, and 1 must be called with S in B8 thru BD, sign comparison set to (B5) XOR (BD), and (B0) in A

Constants in floating (merged sign) notation:

E024

DDE3

E01A

CDBC

E01F

'I.

■Klz

IT

2w

0000 USR(P)

CED6 SORP

CED9 S AND P

D264 FRE(P)

D285 POS(P)

D349 STR$

D5C4 CHR$

D5D8 LEFTS

D604 RIGHTS

D60F MIDS

D654 LEN

D663 ASC

D685 VAL

D6E6 PEEK

D728 S - P

D73C JSR D95E, then S + P

D73F S + P

D7AC normalize P

D8BF LOG(P)

D8FD JSR D95E, then S * P

D900 S * P

D95E [A + 100Y]— S, separating sign, set sign comparison, return with (B0) in A

D9E4 S/P

DA74 [A + 100YJ-P, separating sign

DAA6 roundoff(P)-[X + 100Y], merging sign

DACE S-P

DADE P-S, with rounding

DAE1 P—S, without rounding

DAED roundoff(P)

DAFD SGN(P)-A

DB0B SGN(P)

DB2A ABS(P)

DB9E INT(P)

DE24 SQR(P)

DE2E S I P

DEA0 EXP(P)

DF45 RND(P)

DF9E COS(P)

DFA5 SIN(P)

DFEE TAN(P)

E048 ATN(P)

Conversions: D0A7 P-integer in B3,B4 [100B3 + B4] D278 integer in A,Y [100A + Y] - P

Table 1: Entry points for Commodore PET ROM functions, including floating-point subroutines that are utilized directly by the author's program.

components during the transformation process.

None of this is anything for a nonmathematically inclined person to worry about; it's just a recipe for the machine to follow in order to crank out the answers. There's no more need to follow the details of the process than there is to follow the details of how your pocket calculator computes exponentials or logarithms. In ten or twenty years, as the power of computers grows and their cost shrinks, there will probably be singlekeyword instructions to perform Fourier transforms, just as most machines now have EXP and LOG routines available. Some people will still work with the nitty-gritty, lowlevel algorithms and procedures, just as some engineers work with individual transistors today. But most human work will be done using higher-level languages, where it's easier to invent new concepts and prove theorems. Machines will handle the low-level dirty work.

Besides the specific algorithm I chose to use, some other important decisions went into the design of 2DFT. First, to avoid all danger of arithmetic overflow and underflow, I use floating-point procedures except at the final stage where the results of the transformation are displayed. At that point, the floating numbers are converted into fixed-point integers and any results greater than 255 are truncated to equal 255. (There are never any negative results because the square root of the sum of the squares is always positive or zero.)

To save program space and avoid the headaches of writing my own routines, I call the floating-point procedures in the PET's BASIC ROM. Table 1 is a list of hexadecimal addresses of the entry points to these routines, and includes short descriptions of what each routine does and how to call it. (Driven by my need for machine-language floating-point capabilities, I found the locations of these subprograms, and I don't think that there can be anything wrong with PET owners using the subroutines in their programs, as I've done. I should also note, however, that Commodore and Microsoft may change the addresses given in table 1 in future production of PETs and other machines.)

A second important choice that was made in the design of 2DFT was

182 March 1981 © BYTE Publications Inc

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BYTE March 1981

183

to use the same scales for the horizontal and vertical axes in the Fourier transform. This is not as obvious a choice as it might seem. Because the video display screen isn't square, it might seem to be better to squeeze the vertical scale, so that as many high frequencies could be plotted in the vertical direction as are plotted horizontally. The resulting distortion would be perfectly acceptable math

ematically, but it would make the pictures harder to look at and might be responsible for some mistaken notions on the part of naive viewers. Additionally, choosing different scales for horizontal and vertical transformations would require the use of a different set of sines and cosines for each dimension.

I chose instead to make the scales in the frequency domain equal. The re

Listing 2: This program calls 2DFTand helps translate its results to a form more easily viewed by a human. A picture can be drawn on the screen, using the usual cursorcontrol characters. Hitting the exclamation-mark key turns the picture into a form that 2DFT can read, where each cell has in it a number (from 0 thru 255) proportional to the magnitude of the image at that cell. The quote key turns the numbers back into a "density plot" where the brightness of each cell is proportional to its magnitude.

5 REM»*POKE 135,6 BEFORE RUNNING TO PROTECT MACHINE-LANGUAGE 2DFT PROGRAM

10 DATA 32, 58,59 ,103, 106,118,225.,245,244,229,160:F0R 1-1 TO 10:READ Gt: NEXT

20 TPINT "HIT -RETURN- TO TRANSFORM SCREEN"

30 PRINT " -QUOTES- TO MAKE DENSITY PLOT"

40 PRINT " - ! - TO TURN DENSITY TO NUMBERS"

100 GET AS:IF AS""" GOTO 100

110 I-ASC(AS ):IF 1-13 GOTO 200

120 IF I'34 GOTO 600

130 IF 1-33 GOTO 900

140 PRINT AS;:GOTO 100

200 FYS(1536):SYS(1713 ):GOTO 100

BOO FOR 1-32768 TO 33767:A=PEEK( I ):POKE I,Gt(A/2 5 ) :

900 FOR 1=32768 TO 33767:A-PEEK(I):B=l0:FOR J=0 TO

910 NEXT:POKE I,25«B:NEXT:GOTO 100

020 REM"POKE 135,32 WHEN FINISHED TO REGAIN ACCESSIBILITY TO ALL MEMORY

:NEXT:GOTO 100

:IF A-G1,(J) THEN B=J:J =

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quired sines and cosines are stored in a table (on PET memory page STABPG, in listing 1); a pointer moves through the table, allowing the transformation subroutines to read off the trigonometric functions with a minimum amount of computational overhead. The effect of making the scales equal in both directions is that instead of using a 25- by 40-pixel (picture-element) screen, the program is really transforming a 40 by 40 image. The extra 15 rows are presumed to be filled with zeroes before every transformation. After transforming, the high frequencies that fall outside the bounds of the video screen are not calculated. (This is not a devastating loss; as you may have heard, you can cut off and throw away part of a hologram and still reconstruct the whole original image from the remaining fragment. The only cost is a loss of resolution and sharpness in the reconstructed image. More on this later.)

The third significant choice I made in writing 2DFT was to display the amplitude of the Fourier transform: the square root of the sum of the squares of the sine and cosine components. A photographic plate has a sensitivity that is proportional to the light energy which falls in any given area. Taking the square root adds mathematical complexity and computational time to the transformation process. On the other hand, the square-root operation makes it a lot easier to look at and interpret the transform results on the video screen. It prevents almost all overflows because any number between 0 and 65,535 is mapped into the range 0 to 255 automatically. The cost in time is an additional 10% or so, which is acceptable for the benefits that result. Finally, the nonlinearity of the square root turns out not to interfere much with the holographic process, in my experiments.

The video-character generator used in the PET is capable of storing a number between 0 and 255 in each of the thousand screen locations, but for human viewing, this kind of a display isn't very good. In the BASIC driver program which calls and controls 2DFT, I've included short routines to convert the screen contents to and from a "density plot," where each pixel on the display is filled with a character with brightness propor

184

March 1981 © BYTE Publications Inc

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Photo 1: Photo la shows a simple image of low-frequency components present along the length of the stripes. Perpendicular to the stripes, strong periodicity occurs at frequencies that are multiples of the spacing frequency. The resulting transform is shown in photo lb.

tional to the number formerly stored in that cell (see listing 2). The densityplot display uses only eleven distinct symbols, so it's as if the 8 bits stored in each screen location have been truncated to about 3Vz bits. The loss of precision is not severe, and the density plots are much easier to look at and understand than the raw data.

Experimenting with 2DFT

As I have implemented it, the 2DFT program takes about 4 minutes to do a single complete two-dimensional Fourier transform of the contents of the PET's screen and display the results. (It runs faster if the input data contains many zeroes, since the floating-point multiplication routine in the PET knows how to multiply by zero quite rapidly!) The columns of the answers are plotted as soon as they are calculated. After a computation, 5250 bytes of PET memory are left containing the results of the row transformations in floating-point notation (5 bytes per number). Because the input data was a set of strictly real numbers, fifty of the sine components are always exactly zero (two zeroes per row), and so there are

1000 independent numbers in memory—precisely as many independent numbers as there were cells on the screen. This is not coincidental; the Fourier-transformation process "conserves information," so it had to turn out that way.

For your first experiments, and to confirm that the program is working correctly, I recommend that you transform simple pictures. A good test is a picture made up of parallel stripes (see photo 1). The picture, like a picket fence, has only low-frequency components present in the direction along the length of the stripes. Perpendicular to the stripes, there is a strong periodicity, at frequencies which are multiples of the fundamental spacing frequency. Logically, the transform should be a series of bright spots running along a line perpendicular to the original stripes.

Another good test is to transform a sharp spike—a picture with only one cell illuminated. Such a sharp point is made up of equal amounts of sine waves at all frequencies and in all directions. Thus, the result of transforming a spike should be a

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BYTE March 1981

187

screen with equal intensities in every cell.

One of the first things that you should discover when experimenting with 2DFT is that the absolute location of a picture on the screen doesn't matter. Shifting a picture changes the phases of the sines and cosines that go into making that image, but it does not change the amplitude of the frequency spectrum of that picture. Because only the amplitude and not the phase is displayed, two pictures which differ only by some shift should give the same transforms. (This insensitivity to shifts is one reason for the usefulness of Fourier transforms in pattern-recognition problems!)

Another thing to notice about 2DFT is the relative overall intensity of a picture and its transform. This intensity, of course, is somewhat arbitrary, since by multiplying each element of the transform's sine table by some constant, the whole transformed picture gets multiplied by the square of that constant. (The constant shows up squared because the sine table is used two times, once to transform the rows and once for the columns.)

If none of the transformed image was lost because of the nonsquare screen, it would be possible to adjust the constant that multiplies the sine table so that the sum of the squares of the pixels before a transform equals

the sum of the squares after transforming. The multipler is 1/SQR(L), where L is the length of a side of the square screen.

In my implementation of 2DFT, I tried multiplying every element of the sine table by 1/SQR(32) and have found it to work well. Thirty-two is a reasonable mean value between the length of a row and the length of a column. The exact choice of the constant isn't critical unless you want to be able to read off quantative mathematical transformation results. For experimental purposes, any value that keeps the picture elements from growing too bright or too dim is acceptable.

An obvious quality of the transfor

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mations produced by 2DFT is that they are symmetric about a cell near the center of the video screen. The cell around which everything seems to revolve is the (0,0) cell, the center of the frequency domain. It contains the sum of all of the cells in the untransformed picture multiplied by any factors that were chosen for the sine table. It's also the cell which is most likely to suffer from an overflow problem because all of the pixels in each original image were positive numbers and add together to make a large zero-frequency total. (2DFT displays overflows as a character of maximum brightness, for the number 255.) The rest of the transformed image is symmetric

about the central cell, in the sense that each cell contains the same number as the cell an equal distance away on the opposite side of the middle.

This follows mathematically from the fact that the original image was entirely real, with no imaginary (complex-number) part. You can think of it as just a convention, if you like; to avoid sharp edges which might cut off parts of a picture, we have plotted "negative frequencies" as if they had the same energy as the corresponding positive frequencies.

It works out then that you can think of the opposite edges of the screen as being joined, so that something moving off the screen at

the right-hand side comes in automatically at the left edge. (Between the top and bottom edges, there are 15 unseen lines, however, in order to make the imaginary screen square.) Because there are an even number of columns, one column on each side of the central (zero) column is not duplicated. That column is plotted as the rightmost one on the screen.

It's a good idea to take some time now to draw pictures on the screen, transform them, and try to develop some instincts about what the transforms tend to look like. Many of the results from one-dimensional Fourier analysis carry over to two dimensions. For example, we noted that an

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All software has specific requirements for proper operation such as computer type, equipment configuration and support software.

Check the following codes for system requirements to be certain yoursystem will accept the software offered.

(A) CP/M version 1.4 or higher.

(B) CP/M version 2.0 or higher.

(C) CBASIC-2.

(D) MBASIC version 4.51.

(E) BASIC-80 version 5.0 or higher.

(F) 48K memory or greater.

(G) 56K memory or greater. (H) 64K memory.

(I) Business system: 48K memory, 200K dual disk drives, cursor addressable terminal, and 132 column printer. (K) Cursor addressable terminal. (L) signed license required for shipment. (O) specify 8080, Z80, or CDOS. (P) giveCP/M serial number. (T) serial port and modem. (Z) Z80CPU.

Choose any of 4 ways to order:

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• Call (203) 853-6880.

• Telex 643-788.

• Dial-up our 24-hour computer (300 baud) (203) 853-0816.

Specify prepaid, C.O.D., Master Charge, or VISA. (Please give credit card number and expiration date.)

Specify disk format: North Star Single or Double, Micropolis Mod I or Mod II; 8" single density, or Ohio Scientific.

Prices do not include shipping and C.O.D. In CT add 7'/;% sales tax.

'Manual price will be credited against later purchase of software.

CP/M is a trademark of Digital Research. Z80 is a trademark of Zilog. Inc. PASCAL/M is a trademark of Sorcim. PASCAL/MT» is a trademark of MT Micro Systems. PEACHTREE is a trademark of Retail Sciences. Inc. S-BASIC is a trademark of Topaz Computing. SELECTOR IV is a trademark of Micro-Ap. Inc.

Copyright • 1981 Westico. Inc.

(2b)

(2c)

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image with very fine detail (sharp spikes or narrow lines) in one dimension requires many high-frequency sinusoidal waves to define it; the same is true for two-dimensional pictures. A picture that repeats only a few times across the screen width will have strong low-frequency components in it (components that show up in frequency space near the central zero-frequency cell), while a picture that repeats many times across the screen will have strong components at the higher frequency of repetition. (In your experiments, don't forget

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that you're not seeing the highest vertical frequencies, which fall outside the screen's height.)

You should realize that even though the program uses horizontal and vertical axes to do the mathematical transform, those axes are artificial and not part of the initial or final picture. So, if you're looking at an image which has strong structure trending along a line from northwest to southeast, feel free to tilt your head and define your own personal axes in such a way as to make the image and its transform easier to think about.

Photo 2: This sequence illustrates some of the properties of the holographic transformations as done by the 2DFT program. Photo 2b is the hologram produced from the simple image in 2a. In 2c, the image is reconstructed from the hologram. Note the mirror duplication of the original image and the spreading of the reference spot due to the cut-off of high vertical frequencies by 2DFTs algorithm. A substantial portion of the hologram is zeroed in photo 2d (indicated by the @ symbol), giving the reconstructed image in photo 2e. This reconstruction is fainter and "noisier" than photo 2c, but no part of the overall image is missing.

Holography and Very-LongBaseline Interferometry

One of the most exciting and valuable developments of technology in the past thirty years has been that of holography. Holograms can store information at densities far greater than normal photography, and with far better immunity to noise and loss of data from scratches, dust, etc on the film. An equally exciting develop

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TXTBOOK/ Formatting software for document preparation, technical and theses presentation, plus mass mailings. You and TXTBOOK are in total control of paginanation, margination, and titling, with choice of several footnote styles, automatic table of contents generation, easy insertion of text from external files, and more. Requires 32K CP/M and CBAS1CZ. Manual $!5/Object $100/Source $200.

FRmFLEX/ Three programs that create a series of fixed and/or editable fields with separate CRT input and printer output formats. Thus, your pesky business forms and unusual tabular formats are filled precisely and automatically with simple linear entry of data! The only system of its kind, with unlimited application FRMFLEX allows complete filled/unfilled forms entry, updating, editing, and creative flexibility. Requires 32K CP/M CBASIC2 and CRT with addressable cursor. Manual $20/Object $175/Source $350.

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190 March 1981 © BYTE Publications Inc

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to begin with, color graphics.

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merit in modern astronomy has been the discovery of what's called verylong-baseline interferometry, or VLBI. In a VLBI observation, radio telescopes thousands of kilometers apart look at the same object. The signals which they receive are combined, and by this combination, give a resolving power equal to that of a single telescope as large as the separation between receivers—a telescope as large as the Earth, in some cases!

Even working at wavelengths very long compared to optical light, VLBI techniques enable astronomers to see objects that are hundreds or thousands of times smaller than the largest optical telescopes can resolve. The vast increase in astronomical information-gathering capability has produced new insights during the last few years concerning the structure of distant galaxies and the early history of the universe.

Both holography and VLBI rely on the same secret: the two-dimensional Fourier transform. Using the 2DFT program presented here, it's easy to make and reconstruct one type of hologram, the "Fourier-transform hologram," which is most useful for storing and retrieving two-dimensional information. (Holograms to record three-dimensional objects work on similar principles. See some of the references for more information.) It's also easy to use this program package to experiment with and learn about some of the interferometry problems that radio astronomers face.

Briefly, the results of a very-longbaseline-interferometry observation consist of a map of the object in the sky—a map not in the usual sense, but of the frequency domain. As the Earth's rotation moves the radiotelescope antennas relative to the stars, the signals that the telescopes receive sample different points in the Fourier-transformed plane. With enough observations, using enough antennas, reasonably complete coverage of this transformed map can be achieved.

The big problem in VLBI is to deduce what the astronomical object looks like before transforming. If information about the relative phases of points in the frequency domain were available, it would be possible to unambiguously invert the observations and produce a picture of the object.

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The secret of

holography and its

sophisticated ability to

retain information is

the two-dimensional

Fourier transform.

Unfortunately, VLBI can't (as of today) produce enough phase information. The astronomers have to look at an image in Fourier-transformed space which contains only amplitude information, just like the image that the 2DFT program produces. In some cases, it's not too hard to guess what the object that produced that transform looked like, but observers often must fall back on model making and try to fit the simplest reasonable approximation they can think of to the data. This is a tough subject, but an important one. A lot of research is going on now in an attempt to find better solutions.

Fourier-transform holography is also a subject for vigorous current research. One reason for the interest is that holograms could possibly provide huge, ultra-fast memories for computer systems. Ordinary microfilm is a very inefficient way to record data. It fails to take advantage of the information-storage ability of highresolution photographic film, and if the bit density is pushed up, the microfilm technique becomes unacceptably vulnerable to film defects, dust particles, etc. Conventional photographic methods are too highly localized for each bit that is written—it's like trying to transmit information over a noisy phone line without a decent error-detection and correction code!

A hologram, on the other hand, shares many of the best properties of sophisticated error-preventing techniques. Each bit of the original record is spread out over the entire holographic image. A speck of dust can't clobber a particular bit; all it can do is add a slight overall noise to the recovered analog signal, and even that noise can be entirely removed by a simple digitizing process. If half of a photograph is cut off and thrown away, half of the picture is lost forever. If half of a hologram is removed, the whole picture is still there! The sharpness of the picture is

reduced, but no particular region is lost at all.

How can a hologram work? Photographic film records only the intensity, not the phase, of the light that hits it. The secret is simple: put a phase reference into the original object that is being holographed! This phase reference is just a bright, pointlike spot in the original. When transformed, the bright spot by itself turns into a constant signal over the whole frequency versus space plane because (as mentioned above) a sharp spike is made up of equal amounts of sinusoids at all frequencies.

This constant background signal provides a reference against which the sines and cosines of the other parts of the original object can interfere, constructively and destructively. The background provides the reference phase; the rest of the Fourier-transformed image adds and subtracts relative to that background, and so an intensity recording (as on a photographic plate) includes enough phase information to allow the original image to be reconstructed.

The reconstruction algorithm is simple: just do another Fourier transform of the hologram to return to ordinary space! Mathematically, if phase information is recorded, the operation of Fourier transforming is its own inverse, like the operation of inverting is for numbers. The reconstructed image comes back twice, symmetrically situated about the central zero-frequency spike, but it's easy to mask off one of the two images if necessary.

The 2DFT program is quite capable of taking simple holograms and reconstructing them. Because the transformation is done on a 40 by 40 grid, but only the central 25 rows of forty elements are kept and displayed, some of the high vertical frequencies in the original image will be lost. (That explains the vertical spreading of some of the reconstructions, especially noticeable in the central region.) It's best not to try to recover images with too much fine detail. If the original is made of lines at least two cells thick, it usually comes back quite recognizably.

Note that the bright pointlike spot that provides the reference phase should be brighter than the rest of the original image being transformed; otherwise, the rest of the image tends to act as a (poor) reference phase for

194 March 1981 © BYTE Publications Inc

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198 March 1981 © BYTE Publications Inc

the bright spot. Also note that some errors come in due to overflow and truncation, as only 8 bits of the hologram are recorded on the display. If you want to, you can turn the holographic display of numbers into a density-plot image for inspection—but the resulting truncation to about 3V2 bits means still more noise in the reconstructed image.

It's quite educational to delete a few points (or a sizable fraction) of the hologram, and still see the entire original picture be reconstructed from the remaining fragment. (It may be desirable to change the density-plotting gray-scale factors in some cases, as the image reconstructed from a partially removed hologram is fainter than the usual result.) These are only a few suggestions — try inventing experiments of your own!

A final word about very-long-baseline interferometry: if it is known that the astronomical object under observation contains a bright, pointlike source in or near itself, it is possible to completely reconstruct a map of the original source. The bright spot acts as a phase reference for the radio astronomers. In fact, what they're reconstructing is just a Fourier-transform hologram—but on a galactic scale!

Further Work

After a program is written, it's always possible (and sometimes profitable) to go back and see how it could have been done differently, and perhaps better. The 2DFT program is no exception; I have several ideas for improvements and modifications, some of which you may wish to try. First, now that I know not to be afraid of cutting off parts of the holographic image, I've wondered whether a 64- by 64-cell transform would be the best step up. Since the dimensions are powers of two, it would be possible to use the fastFourier-transform algorithm and save time by at least a factor of 6 (the logarithm of 64 to the base 2) over the slow method. I also think that it might be worthwhile to use fewer bits during the transform, since overflows haven't been as deadly as I feared before starting the project. Perhaps integer arithmetic with 1 or 2 bytes for the numbers would work; it would certainly save space and time over the 5-byte floating-point meth

ods that are used by the PET's firmware algorithms. (BASIC integer operations on the PET are actually done almost entirely in floating-point arithmetic; the only benefit of integers that I know of is to save memory in large arrays.)

I've seen comments about 1-bit Fourier transforms in some references. If that is a reasonable technique, you could use the Vi-cell graphics capabilities of the PET screen to display 50- by 80-pixel transformed images.

Finally, there must be a better way to find the amplitude of the transformed data than to take the square root of the sum of the squares of the sine and cosine parts. (The PET's floating-point square-root algorithm simply raises the argument to the Vz power, by taking a logarithm, multiplying, and exponentiating. It's not overly fast!) Perhaps a little table lookup could get a fast square root with sufficient accuracy for display purposes.

There are surely other improvements to be made on 2DFT. But as it is, it has provided me with a powerful learning tool. I've developed a more intuitive understanding of holography and the Fourier-transform process than I ever had before...and it's been fun! I hope you enjoy it as much.B

References

1. Beasley, M J. Lasers and Their Applications. Taylor & Francis Ltd, 1976.

2. Bracewell, Ron. The Fourier Transform and Its Applications. New York: McGraw-Hill, 1965.

3. Cathey, W Thomas. Optical Information Processing and Holography. New York: John Wiley & Sons, 1974.

4. Cohen, Marshall H. "High-Resolution Observations of Radio Sources." Annual Reviews of Astronomy and Astrophysics, volume 7, 1969.

5. Collier. Robert J, Christoph B Burckhardt, and Lawrence H Lin. Optical Holography. Academic Press, 1971.

6. DeVelis, John B and George O Reynolds. Theory and Applications of Holography. Reading MA: Addison-Wesley, 1967.

7. Gabor, Dennis. "Holography, 1948-1971." Lecture givenon the acceptanceofthe Nobel Prize in physics, 1971. Reprinted in Laser Devices and Applications, edited by Ivan P Kaminow and Anthony E Siegman, IEEE Press, 1973.

8. Ryle, M. "Radio Telescopes of Large Resolving Power." Lecture given on the acceptance of the Nobel Prize in physics, 1974. Reprinted in Reviews of Modern Physics, volume 47, number 3, July 1975.

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Editorial.

Text continued from page 10:

listed at the end of this editorial.

"It looks like too much trouble": Most of the things you'll need to do are easy and make sense. After a while, they will become so natural that you'll wonder how you ever did without them.

"/ don't have the time to spare—I'm on a tight deadline": You have time to debug, don't you? And you have time to fix that bug that appears six months after you wrote the program. Actually, the techniques of design (which include structured programming during the program design and implementation) take up less time due to decreased time in testing, debugging, and maintenance. In fact, what you're doing is spending more time in design (doing it right) and less time in testing and debugging (finding and fixing what you didn't do right the first time).

"It takes all the fun (or mystery) out of programming": This is a difficult question to answer because there's an element of truth in it. But what do you mean by "fun"7 If you mean surprises or adventure, you're right—there's less of that because you know more of what is going to happen before you start coding; on the other hand, there's less frustrating debugging. There's less exultation when a program finally works—but there's also quite a bit of pride in the knowledge that it will stay working. Proper design takes some of the mystery out of programming. Programming becomes a skill, but it is designing that becomes the art.

Finally, if you are programming for a living, haphazard programming may be "fun," but can you afford such fun? Untraceable bugs and unreliable programs decrease your productivity and your effectiveness. Can you and your company afford that?

Some Design Tools

The following briefly describes three design tools that have been available for at least five years. Data flow diagrams (DFDs) are usually used on large projects, although they can help clarify your thinking on simpler ones. They force you to clarify what information is being manipulated and how it "flows" through the project. On a level of design several steps closer to coding, structure

Figure 2: An example of a data flow diagram (DFD). The circles represent processes (or actions) we are interested in within a system. The boxes represent external systems. The parallel lines represent data files (often called data stores), and the lines represent groupings of data that are transformed by the process.

200

March 1981 © BYTE Publications Inc

Circle 125 on inquiry card.

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Ciarcia's Circuit Cellar

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Volume II features 19 articles, including 14 that were voted by BYTE's readers as the best articles of the month, such as: Build a Computer-Controlled Security System, Communicate On a Light Beam (laser communications), Anyone Know the Real Time? (real-time clocks), The Intel 8086, Add Nonvolatile Memory to Your Computer, Computerize a Home (AC remote control from your computer), A Computer-Controlled Wood Stove, Ease Into 16-Bit Computing (The Intel 8088), and I/O Expansion for the Radio Shack TRS-80: Parallel and Serial Ports.

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Volume I contains a collection of more than a year's worth of the popular series Steve writes for BYTE magazine. Included are six winners of BYTE's On-going Monitor Box (BOMB) award voted by the readers as the best articles of the month: Control the World (a four-channel digital-to-analog converter for controlling appliances and other devices); Memory Mapped I/O; Program Your Next EROM in BASIC; Tune In and Turn On (a computerized wireless AC control system); Talk To Me (add a voice to your computer); and Let Your Fingers Do the Talking (a touch panel for your video display).

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Editorial.

charts are hierarchical models of a system that emphasize the tasks and subtasks to be performed and the data that passes among them. Finally, on the lowest level of design before coding, structured pseudocode is an informal English-like coding that allows you to experiment with implementing the logic of a program without being bothered with the narrow grammar of a particular computer language. Although I'll give an example and a short explanation of each method, you should refer to some of the books described at the end of this editorial for further details.

An example of a data flow diagram is given in figure 2. The circles represent processes we are interested in (actions being performed, not states of the system), and the arrows represent some grouping of data that is being transferred from one activity to another. The rectangular boxes represent other systems that interact with our systems but that are not of interest to us. If the arrows lead out of these boxes, they are called sources; if the arrows lead in, they are called sinks. The two parallel lines represent data files (also called "data stores") that store information for later use; depending on the file, arrows may go in both directions.

Data flow diagrams are usually used in groups, with one diagram representing the interaction of the system with external systems (one circle interacting with several boxes) and each of the other diagrams representing one circle from a "higher" diagram. For example, figure 3a shows an overview DFD of (a simplified version) the in

teraction between the BYTE editorial department and the rest of the world. Figure 3b shows an expansion of the single circle in figure 3a. Further data flow diagrams can be used (if needed) to subdivide a given process.

When a set of DFDs covers several levels, the circles in the subordinate diagram reflect the identity of the parent circle. For example, the processes (circles) in a diagram representing process 1 of figure 3b ("log in and schedule manuscripts") would be numbered 1.1, 1.2, 1.3, and so on; similarly, subordinate processes of 1.3 would be labeled 1.3.1, 1.3.2, 1.3.3, and so on.

A data flow diagram is useful only when it meets certain criteria. Although I can't give all the dos and don'ts, the following points are helpful: First, take care that circles represent meaningful data transformations and arrows represent meaningful collections of data. For example, "read card deck" is not a meaningful transformation, but "classify incoming orders" is.

Second, with one exception, the inputs and outputs to a given diagram must be the same as those for the single process the diagram represents in the next higher diagram. This rule makes sense, and checking diagrams for compliance often alerts you to some data flow you've ignored. The one exception to this rule is that arrows for rejected data on one level are not shown in the next higher level (for example, see "manuscripts with no name or return address" coming out of process 1 in figure 3b); the reason for this convention is to avoid cluttering up the diagrams.

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BYTE March 1981

203

Editorial,

(3a)

NCOMING MANUSCRIPTS

BYTE

EDITORIAL DEPARTMENT 1

FINISHED 1 MANUSCRIPT

AUTHORS

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REJECTED I MANUSCRIPT \ WITH LETTER^

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MANUSCRIPTS WITH PRIMARY EDIT DONE

Figure 3: Overview and detailed data flow diagrams. Figure 3a shows an overview data flow diagram of the interaction of the BYTE editorial office with the rest of the world. Figure 3b is a detailed data flow diagram showing the workings of circle 0 in figure 3a. (The system shown has been simplified for purposes of illustration.)

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BYTE March 1981 205

Editorial.

Third, data flow diagrams should show the logical flow of data, not its physical flow in an existing system—a DFD is not a flowchart. For example, circle 1 in figure 3b should not be labeled "Karen," even though she logs all incoming manuscripts.

In conclusion, the data flow diagram is a planning tool used in the early stages of design. It can clarify the flow of data in either an existing or a proposed system. You'll probably draft many versions of a data flow diagram before you arrive at a satisfactory version—this is a normal and unavoidable consequence of your increased understanding of the system and the improvements you are making in its design.

It's particularly important to use data flow diagrams when you are working for someone other than yourself (for example, a partner or client) because DFDs give you an easily understood document from which the other person can contribute at an early stage in the design process. This early feedback can often prevent costly backtracking in the later stages of system implementation.

The Structure Chart

Structure charts are used later in the design process, when you know what a system (or program) is to do but want to organize the design and interaction of modules. Structure charts can be used to design either a single program or a system of programs; if you are designing a system, a finished structure chart will suggest logical ways in which to group the modules of the system into programs.

In a structure chart (see figure 4), rectangular boxes represent modules that perform a given action. The organization of the modules is determined by the arrows interconnecting them; the one being pointed to is used by the one doing the pointing to carry out its task. The modules communicate in much the same way as people do in a military hierarchy: the higher (calling) modules are organizers, sending orders to the ones below; the lower (called) modules are workers, performing their tasks (often calling modules that they command) and reporting back to their superiors. However, in this situation, it is the data that is transmitted up and down between modules. The structure chart records this movement. The arrow that begins with an outline circle represents data being passed (eg: an employee record, a part number), and an arrow beginning with a filled-in circle represents a logical flag (eg: transaction-valid or invalid-account-number flag).

Figure 5 i s a n example of a structure chart a t work. The task being illustrated (top box) is the writing of an (imaginary) order for a final article payment to a BYTE author. Note that the data can pass both up and down, depending on the situation, but that logical flags almost always pass yes/no-type control information up to a calling module. The vertical lines on the box "get valid article record" (in the second row of figure 5) indicate that it is a library module that can be used as is from an existing library of routines.

A structure chart shows the subdivision of a system into modules, the hierarchy of those modules, and the data that passes among them. It does not imply anything about the method used to implement a module, nor does it imply a left-to-right execution sequence for modules on

the same row. Again, the main benefit of structure charts is the clarity of design they produce. Creating the structure chart forces you to be precise about what needs to be done. Once completed, the structure chart gives you the opportunity to find logical design flaws and to check for overall completeness. As with the data flow diagram, you'll probably write several versions of the structure chart before you get one that will satisfy you; but, in doing so, you'll create a design that will lead to a much better system or program.

Structured Pseudocode

Structured pseudocode is used only after you've passed the boundary from system design to program design. By the time you're ready to use structured pseudocode, you have already specified the function of the program and some of its implementation details. Writing structured pseudocode is like writing a program for an imaginary machine that understands English-like phrases; it is a "test run" for the real thing, coding the actual program in the strict grammar of BASIC, FORTRAN, or some other computer language. Structured pseudocode tells what is to be done, the order it is done in, and how it is done. Once the structured pseudocode has been written, studied, and rewritten to your satisfaction, you can easily code your computer program from the pseudocode.

Listing 1 gives a short example. The hypothetical task is to find the lump-sum payment for an article from a lookup table, given the classification number of the desired article (which is the key field of the lookup table). We'll assume that the lookup table has two fields, a classification number and a payment amount, and that a sequential search of the table is made to find the appropriate line.

Listing 1 shows what's being done more clearly than an equivalent BASIC (or even Pascal) program because it's not concerned with rigorously expressing the algorithm in the narrow (and therefore less meaningful) grammar of the computer language. Still, since the pseudocode follows (or should be written to follow) the style of the target language, writing the actual program is simply a matter of expanding the lines of pseudocodes to take care of all the necessary details. For more information on con

CALLING MODULE

DATA USED JO

• FL

DATA USED

LOGICAL FLAG RETURNED

Figure 4: An example of a structure chart. The boxes represent modules that perform specified actions, with the higher boxes pointing to the subordinate boxes that they use. An arrow with an outline circle represents a grouping of data, while an arrow with a filled circle represents a logical flag that transmits the results of some yes/no-type evaluation.

206 March 1981 © BYTE Publications Inc

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208

BYTE March 1981

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BYTE March 1V81

209

Editorial ____^_—^_^—_

verting structured pseudocode to BASIC, see my article, "Applied Structured Programming," in the book Program Design: Programming Techniques, Volume I (listed at the end of this editorial).

At this point I'd like to break my earlier promise and say a few good words about structured programming, which is the design philosophy behind structured pseudocode. Structured programming asserts that any program can be written as a combination of three programming structures: a sequence of events, one of two events chosen by the value of a condition (the if...then...else construct), and an event repeated as long as a condition is true (the while...do construct). Structured programming goes hand-in-hand with top-down design (also called programming by stepwise refinement), which says that you solve a programming problem by breaking it into subproblems and continually subdivide these subproblems until each one can be easily coded. This process results in manageable, modular programs that are easy to understand, debug, modify, and maintain. The importance of such advantages cannot be overemphasized, especially if you program for a living.

Some Good Books

You will find the following books helpful if you're interested in structured programming, program design, or system design. The first books deal primarily with structured programming and program design, while the latter ones go deeper into long-range design.

Programming Proverbs by Henry F Ledgard (Hayden Book Company, Rochelle Park NJ, 1975): This is a

friendly, but thorough, folk classic on methodical programming. It contains 26 proverbs with examples and some additional material on top-down design, and it can be read and understood by almost everyone with some programming experience. The languages used in the examples are ALGOL 60 and PL/1. The author, along with several coauthors, has tailored the same material for different books that emphasize FORTRAN, COBOL, BASIC, and Pascal. The titles are: FORTRAN (or COBOL or BASIC or Pascal) with Style: Programming Proverbs. All are published by Hayden Book Company.

The Elements of Programming Style, Second Edition by Brian W Kernighan and P J Plauger (McGraw-Hill, New York NY, 1978): Written in the style of Strunk and White's Elements of Style (the English language style book), it is slightly more formal and not as folksy as Programming Proverbs. It covers its material more methodically than Programming Proverbs does.

A Collection of Programming Problems and Techniques, by H A Maurer and M R Williams (Prentice-Hall, Englewood Cliffs NJ, 1972): I've always enjoyed leafing through this book because of all the tidbits of information it possesses. It includes such diverse information as the Ackermann function, algorithms involved with reverse Polish notation, and information on generating magic squares and solving simultaneous equations by the Gauss-Seidel method. An excellent book for problem ideas if you're teaching programming or need a short, nontrivial problem to illustrate a point.

Software Debugging for Microcomputers, by Robert C Bruce (Reston Publishing Co, Reston VA, 1980):

WRITE ARTICLE CHECK ORDER

ARTICLE NUMBER

1REC0RDNOT-FOUNC FLAG

ARTICLE RECORD

CLASSIFICATION- ♦ INVALID FLAG |

GET VALID

ARTICLE

RECORD

CLASSIFICATION NUMBER

LOOKUP TABLE

CALCULATE CHECK AMOUNT FOR LUMP-SUM ARTICLE FROM LOOKUP TABLE

ARTICLE RECORD

CHECK AMOUNT

CALCULATE CHECK AMOUNT FOR PER-PAGE ARTICLE

ARTICLE RECORD

CHECK AMOUNT

WRITE ORDER FOR CHECK

GROSS AMOUNT FOR CHECK

DEDUCT AMOUNT ALREADY PAID

Figure 5: Another example of a structure chart. The (hypothetical) action illustrated is the generation of an order for a check for final payment to a BYTE author for an article. The vertical bars on the first and last boxes in the middle row represent predefined modules that can be used in different situations.

210 March 1981 © BYTE Publications Inc

dBASE II vs. the Bilge Pumps.

by Hal Pawluk

V\fe all know that bilge pumps suck.

And by now, we've found out—the hard way—that a lot of software seems to work the same way.

So I got pretty excited when I ran across dBASE II, an assembly-language relational Database Management System for CP/M. It works! And even a rank beginner like myself got it up and running the first time I sat down with it.

If you're looking for software to deal with your data, too, here are some tips that will help:

Tip #1: Database Management vs. File Handling:

Any list or collection of data is, loosely, a data base, but most of those "data base management" articles in the buzzbooks are really about file handling programs for specific applications. A real Database Management System gives you data and program independence (no reprogramming when data changes), eliminates data duplication and makes it easy to turn data into information.

Tip #2: Assembly Language vs. BASIC:

This one's easy: if you're setting up a DBMS, you're going to be doing a lot of sorting, and Basic sorts are s-l-o-w. Run a benchmark on a Basic system like S*-IV against a relational DBMS like dBASE II and you'll see what I mean. (But watch it: I've also seen one extremely slow assembly-language file management system.)

Tip #3: Relational vs. Hierarchal & Network DBMS.

CODASYL-like hierarchal and network systems, around since the 1960's, are being phased out on the big machines so why get stuck with an old-fashioned system for your micro? A relational DBMS like dBASE II eliminates the predefined sets, pointers and complex data structures of a CODASYL-type DBMS. And you don't need to be a programmer to use it.

dBASE II vs. everything else.

dBASE II really impressed me. Written in assembly language (with no need for a host language), it handles up to 65,000 records (up to 32 fields and 1000 bytes each), stores numeric data as packed strings so there are no roundoff errors, has a superfast multiple-key sort, and supports ISAM based on B* trees.

You can use it interactively with English-like commands (DISPLAY 10 PRODUCTS), or program it (so when you've set up the formats, your secretary can do the work). Its report generator and userdefinable full screen operations mean that you can even use your existing forms.

And if all this makes your mouth water, but you've already got all your data on a disk, that's okay: dBASE II reads your ASCII files and adds the data to its own database.

Right now, I'm using dBASE II with my word processor for budgeting, scheduling and preparing reports for my clients.

Next come job costing, time billing and accounting.

An Unheard-of Money-Back Guarantee.

dBASE II is the first software I've seen with a full money-back guarantee.

To check it out, just send $700 (plus tax in California) to Ashton-Tate, 3600 Wilshire Blvd., Suite 1510, Los Angeles, CA 90010. (213) 666-4409. Test dBASE II doing your jobs on your computer for 30 days. If, for some strange reason, you don't want to keep it, send it back and they'll refund your money.

No questions asked.

They know you don't need your bilge pumped.

AshtonTate

©AshtonTate 1980

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BYTE March 1981

211

Editorial,

Although this book has little to do with structured programming or design, I mention it because of its thorough treatment of debugging techniques. If you're interested in such debugging techniques as forcing, block debugging, snapshots, and patching, you should read this book.

Listing Is Structured pseudocode for a routine to find a value from a lookup table. The lookup table contains two fields, classification-number and check-amount, and this routine finds the appropriate check-amount by matching a given classification number to the classification numbers in the table. A sequential search is used, starting at the top of the table. If a classification-number match is made, the check-amount needed is the check-amount entry in the same line, and the error-flag (for the information of the calling routine) is cleared. If no match is made, check-amount is set to zero and the error-flag is set.

while not-at-end-of-file and match-not-found

compare classification number of current line with classification

number sought

ii the two are equal

check-amount sought is check-amount field in current line eke

add 1 to table-index endil endwhile

ii no-match-found set error-flag eke check-amount = 0 clear error-flag endil return (to calling routine)

Program Design: Programming Techniques, Volume I, edited by Blaise W Liffick (BYTE Books, Peterborough NH, 1978): This book contains new material and articles reprinted from BYTE. Subjects include "Top-Down Modular Programming;" "Some Words About Program Structure" (both by Albert D Hearn); "Applied Structured Programming" (by me); "Decision Tables: How to Plan Your Programs" (by Thomas G Bohon), and several other helpful articles. My only regret is that several articles include what are called "Warnier-Orr diagrams," a program design technique I do not recommend.

A Primer on Structured Program Design, by Gary L Richardson, Charles W Butler, and John D Tomlinson (Petrocelli Books, New York NY, 1980): This book covers structured programming and program design, but it also touches on the larger elements of system design. One nice feature is that it briefly lists several different design tools in order to help you choose the one you like best.

Classics in Software Engineering, edited by Edward Nash Yourdon (Yourdon Press, New York NY, 1979): I cannot say enough good things about this book. It is a compilation of all the pivotal papers in the fields of structured programming (both theory and practice), program and system design, and other related fields. Not only is it extremely convenient to have these articles gathered together, it's also the only way most people will ever see them (since many of the articles appeared in the proceedings of computer conferences as many as 15 years ago). By reading the articles (and the excellent introduc

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BYTE March 1981 213

GET THE

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You want a copy of the exciting software system that's going places. Professionals everywhere are using the UCSD p-System. Now, you can have it. The UCSD p-System offers: a complete software development system, your choice of languages, and a portable system that runs on your microcomputer today and tomorrow. Send in the coupon below and join the pros today. Phone orders accepted with Visa or Master Card.

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My system has: (check only one)

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□ PDP-11 with D RX01 □ RX02 (check one)

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La ^^ <^B M <^» <^» ^^ <^» W <^B <^» MM ^B <^» ^^ M^J

Editorial.

tions to each article, written by Mr Yourdon), you can see how the key ideas in the field formed and grew. The highly theoretical article, "Flow Diagrams, Turing Machines, and Languages with Only Two Formation Rules," by C Bohm and G Jacopini, contains the theoretical rigorous proof that any program can be written using only sequence, choice (if...then...else), and iteration (while...do). Although I don't have the room to list all the articles in this 424-page book (most of which are remarkable in some way), I must mention "The Humble Programmer," by Edsger Dijkstra; "Revolution in Programming: An Overview," by Daniel McCracken, and the monumental "Structured Programming with go to Statements," by Donald Knuth.

The Practical Guide to Structured Systems Design, by Meilir Page-Jones (Yourdon Press, New York NY, 1980): This is a very readable book explaining the latest design techniques. I enjoyed reading it, and I referred to it constantly while writing this editorial. It covers the three techniques discussed above, as well as several I didn't have room for (the concept of a "data dictionary," for one), and it is greatly enhanced by the inclusion of a complete case study of a system designed using the methods given in the book. The book concentrates on the design process and talks only briefly of structured programming and program design. Also, it presents much the same material as the next two books (which come before it chronologically), with a slight reduction in complexity and a slight increase in readability. I recommend that you read this book first.

Structured Analysis and System Specification by Tom DeMarco (Prentice-Hall, Englewood Cliffs NJ, 1979): This book covers much the same material as the preceding book, but it treats the subjects covered more rigorously and a bit more formally. It also addresses the special problem of modeling and designing very large systems that don't yet exist.

Structured Design: Fundamentals of a Discipline of Computer Program and Systems Design, by Edward Yourdon and Larry C Constantine (Prentice-Hall, Englewood Cliffs NJ, 1979): This book is the parent of the two just described (the first publication of this book was in 1975, and the authors of all three books come from the same school of design). Because it was written to describe its design techniqes for the first time, the notation used is a bit cluttered (compared to the streamlined design used in the last two books), but this book is easily the most comprehensive and the most theoretical; it attacks the problem of program design on the broadest level. Particularly important are the ideas of coupling and cohesion among program modules, each of which have separate chapters in the book.

Conclusions

If I had to give you one word to associate with the concept of design, that word would be forethought. Design is forethought—it's as simple as that. Few people would say that they program without forethought, but programming at the keyboard (or with a coding sheet) without design is the same as playing the piano without sheet music— more improvisation than rendition. So the question is no longer, "Is this really necessary?" It's "can you afford not to?"B

214 March 1981 © BYTE Publications Inc

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BYTE March 19B1 215

Technical Forum

DATALINE

Daniel S Hunt, 829 Presidio Dr, Costa Mesa CA 92626

There is a certain pleasure in writing assemblylanguage subroutines for my Microsoft BASIC system; however, the dismal tedium involved in hand-converting object code into BASIC data statements is unmatched.

There are alternatives: one method is to put the object code into a data file and read it into memory for execution by the program. The disadvantage with this method is that one must keep a separate file for what is in essence a subroutine. Besides, the file may be lost in a backup operation or during insouciant copying of the BASIC code to another disk.

My solution for this problem was to write DATALINE. DATALINE is a BASIC program that takes freshly assembled object code and moves it into DATA statements so that the code can be integrated with the BASIC mainline source code.

This program assumes that you are able to move object code into a memory area protected from BASIC. If you do not have the ability to move blocks of object code in this way, the concatenation routine can be joined with an

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algorithm to read a .COM file character by character.

To use DATALINE, load the object code into an area protected from BASIC. The program will prompt you for the load address, length of the program in 64-byte segments, a file name, and a starting line number. It peeks the object code byte by byte and concatenates a string conversion of each byte to a line composed of line number, " DATA ", plus appropriate spaces and commas between each byte value. Eight bytes are put on each data line. The line is filed serially, and it appears to BASIC to be a program file saved in "A" mode. You can merge the data lines with your BASIC program by using the MBASIC MERGE command.

This program includes one of my most used library routines. This is a procedure that takes a hexadecimalvalue input at the keyboard and converts it to decimal representation which can be used in PEEK and POKE statements. As the MBASIC 5.1 interpreter is intolerant of integer overflow, the conversion is to single-precision floating-point base 10, rather than integer. While integer conversion is possible, the extra speed gained in the exercise is not worth the extra code or the increased complexity.

If your BASIC is an older version of Microsoft, merely reduce the length of the variable names where your interpreter rejects one here.

Listing 1: Written in Microsoft BASIC, this short routine takes the drudgery out of writing assembly-language subroutines for BASIC programs. The program rewrites object code as BASIC DATA statements, as shown in listing 2.

MBASIC DATALINE WRITER

Written by Daniel S. Hunt, April 25, 1980 MBASIC 5.1 INTERPRETER / Sol-20

10 REM

100 '

110

120 '

130 '

140 '

150 WIDTH 64

160 PERSE = &HCOD5 : 'SOLOS CLEAR SCREEN CALL

170 CALL PERSE:PRINT:PRINT

180 PRINT "— MACHINE CODE / DATA LINE WRITER —":PRINT

190 INPUT "Enter hex base address of oject code ",HXIN$

200 GOSUB 350 :' CONVERT HEX STRING TO REAL DEC.

210 DBASE = BASETEN

220 INPUT "Routine length in 64-byte segments ".PAGES :

LENGTH = PAGES * 64 230 INPUT "Enter name of data statement file ",DFILE$ 240 OPEN "0",1,DFILE$

250 INPUT "Enter line number of starting data statement ",LNUM 260 LASTBYTE = DBASE + (LENGTH -1) 280 GOSUB 570 :'CREATE DATA LINES 290 CLOSE 310 ' 320 '

330 REM - CONVERTS HEX INPUT STRING TO DECIMAL — 340 '

350 CUME = 0

360 HDATJ = "0123456789ABCDEF" 370 CHARPOS% = LEN(HXINS) 380 FOR 1% = 1 TO LEN(HXIN$) 390 ADDER =0

400 FOR 1% = 1 TO LEN(HDATS)

410 IF MID$(HXIN$,I%,1) = MID$(HDAT$,I%,1)THEN

ADDER = J% - 1 Listing 1 continued on page 218

216 March 1981 © BYTE Publications Inc

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100% Continuous Duty Cycle

High Performance

Low Profile for Desk Top Installation

<s

Low Cost

100 Million Character Print Head

Stylish, Measures 15" wide, 9" deep & 3.5" high

Human-Engineered for Ease of Service

'High-Quotient of performance to cost.

DISTRIBUTOR/DEALER INQUIRIES INVITED

.X. U I r , 11! C. 745 Atlantic Avenue, Boston, MA 02111 • (617) 482-4214

Circle 137 on Inquiry card.

BITE March 19B1 217

Circle 138 on inquiry card.

TOUGHEST BOARDS IN TOWN

FOR S-100's

Monitor and control

in wicked environments.

Want to put your S-100 system to work in the world of computerized monitoring and process control?

Dual Systems has all the boards it takes to do the job in the toughest factory environments. All are designed to function dependably in the real world of industrial control. All operate with Cromemco, North Star and other S-100 systems. A/D board. 12-bit precision. 32 singleended inputs. Or 16 differential inputs. 25 i*.s conversion time. Vectored interrupt. $635. Or $725 with 1 to 1000 gain transducer amplifier. Works with our thermocouple compensation board and our 4-20 mA input boards as well. D/A board. Four independent channels. 12-bit precision Input is binary or 2's complement. Compatible with all existing I/O mapped software. $495. Drives our amplifier board which outputs 4-20 mA. CMOS RAM board. On-board battery back-up preserves data a year. 200 ns read/write time. Runs at 4 MHz. 8K bytes $590.16K bytes $990. CMOS clock board. On-board battery back-up keeps clock running a year. New LSI chip carries date, hours, minutes and seconds. Read or write directly from I/O port. Vectored interrupt. $250.

We also provide complete mainframe systems. OEM and dealer inquiries are invited.

Contact Dual Systems Control Corp., Dept. B, 1825 Eastshore Hwy., Berkeley, CA 94710. Phone (415) 549-3854.

Technical Forum,

Listing 1 continued:

420 430

440

450

460

470

480 490 500 510 520 530 540 550 560 570 580 590 600 610 620 630

640 650 660 670 680 690 700 710 999

NEXT

' { CASE CHARPOS% OF } IF CHARPOS% = 4 THEN

CUME = CUME + (ADDER * 4096) IF CHARPOS% = 3 THEN

CUME = CUME + (ADDER * 256) IF CHARPOS% = 2 THEN

CUME = CUME + (ADDER * 16) IF CHARPOS% = 1 THEN CUME = CUME + ADDER ' { END CASE }

CHARPOS% = CHARPOS% - 1 NEXT

BASETEN = CUME RETURN

-CONVERTS OBIECT CODE TO BASIC DATA LINES

FOR I = DBASE TO LASTBYTE STEP 8 LNUM$ = STRJ(LNUM) + " " DATL$ = LNUMJ + "DATA " FOR J = 0 TO 7

BYTE - PEEK(I + J)

IF I = 7 THEN

BYTES = STRS(BYTE) ELSE BYTE$ = STRS(BYTE)

+ CHR$(44) +

DATL$ = DATL$ + BYTES

NEXT

PRINT DATL$ :' TO CRT

PRINT #1, DATL$ :' TO FILE

LNUM = LNUM + 10 NEXT RETURN END

Listing 2: A "verification run" of DATALINE in a CP/M operating-system environment shows that assembly-language object code is converted into DATA statements for embedding in a BASIC program.

A>asm qtab.aax CP/M ASSEMBLER

VER 1.0

ROUTINE TO INITIALIZE TAB STOPS ON QUME

9000 = 00F8 = 00F9 = 0040 = 0080 = 001B = 0020 = 000D = 000A = 0009 = 0001 = 000F = 000E = 000A =

9000

9000 210000

9003 39

9004 226890

ASEG '*'*' DECLARATIONS *** CACHE EQU

ROUTINE ORIGIN

SERSTAT

SERDAT

SDR

STBE

ESC

SPC

CR

LF

HT

ONE

SI

SO

NUMTBS

EQU EQU EQU EQU EQU EQU EQU EQU EQU EQU EQU EQU EQU

ORG

BEGIN MAIN PROGRAM" NIT:

LXI H.0000H

DAD SP

SHLD OLDSTK

9000H 0F8H 0F9H 40H 80H 27D 32D 13D 10D 09H 01H 15D 14D 10D

CACHE

;ZERO REGISTER SO THAT

;VALUE PASSED TO H = SPC

SETTING

;SAVE OLD STACK POINTER

ADDRESS Listing 2 continued on page 222

218 March 1981 © BYTE Publications Inc

QMEGA "WHOLESALE COMPUTER PRICES"

SALES CO.

DIRECT TO THE PUBLIC

East Coast: 12 Meeting St., Cumberland, RI 02864 West Coast: 3533 Old Conejo Rd., #102, Thousand Oaks, CA 91320

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Atari 850 Interface Module $159 Atari 825 Printer $695

Okidata Microline SO

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704-9 $1250

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703-9 $1550

OMEGA OFFERS THE BEST DELIVERY AND PRICE ON: APPLE • ATARI • TRS-80 Model II • INTERTEC •

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OMEGA sells only quality merchandise to our customers. OMEGA will try to match any current advertised price with similar purchase conditions.

Before you buy anywhere else — be sure to call OMEGA Sales Co.

WEST COAST: 1-805-499-3678 EAST COAST: 1-401-722-1027

OMEGA ships via UPS, truck, or air. COD's. Visa, Mastercharge accepted, with no service charge.

Telex: 952106

Circle 139 on Inquiry card.

BYTE March 1981

and Lightning Fast J

K5

m

■,..

the CompuPro Disc Controller Board is here,

Speed? The CompuPro Disc Controller Board has properly implemented DMA (direct memory access), with arbitration, and fullyconformstoall IEEE696/S-100 specifications. Runs with 6 MHz Z80s* as well as 8080,8085, and 8088 CPUs.

Versatility? Controls single or double sided disc drives, 5" or 8" discs (including 96 track high density minif loppies), single or double density (soft sector).

Reliability? Uses industry-standard, third generation controller chips and the same design excellence that is a part of every CompuPro product.

We weren't going to put out another me-too disc controller board.. .and we didn't.

CompuPro

' - is|S

OAKLAND AIRPORT, CA 94614 (415) 5620636

Call (415) 562-0636, 9 AM to 5 PM PST, for the name of your nearest CompuPro retailer.

220 BYTE March 1981

'Z80 is a trademark of Zilbg

Circle 140 on inquiry card.

TnrcHipfpWspSBiR^P^icffr

High

Performance, High Throughput.

Unlike "all-in-one" computers, CompuPro's modular S-100 systems are amazingly flexible machines that are ideal for high level industrial, commercial, and scientific applications. Full conformance to all IEEE 696/S-100 specifications ensures well integrated systems performance, as well as freedom from obsolescence in the years to come.

All CompuPro products meet the most demanding mechanical and electrical standards, accept the highest possible clock speeds for maximum throughput, and are backed with one of the best- if not the best-warranties in the business (1 year limited warranty on all products, 2 year limited warranty with board exchange program for boards qualified under the Certified System Component program).

When you're looking for a computer, there are lots of choices. But when you need a precision machine that is built for the future as well as the present, the choice narrows down to the most experienced name in the S-100 business: CompuPro.

NEW! COMPUTER ENCLOSURE 2

Introductory price: $795 (specify rack mount or desk top version)

Now it's easy to move up to an expandable S-100 system. . .COMPUTER ENCLOSURE 2 is ready to accept boards the minute it's unpacked. Fused, constant voltage power supply provides +8A at 25 Amps (!), +16V at 3 Amps, and -16V at 3 Amps. Also includes 20 slot shielded/active terminated motherboard, dual AC outlets on rear, heavy-duty line filter, circuit breaker, quiet ventilation fan, reset switch, and black anodized front panel (desktop version includes textured vinyl painted cover). Rack mount version includes slides for easy pull-out from rack frame.

Also available: COMPUTER ENCLOSURE 1. Same as above, but less power supply and motherboard. $289 desktop, $329 rack mount.

SYSTEM SUPPORT 1

MULTIFUNCTION BOARD

$295 Unkit. $395 A/T, $495 CSC

This multi-purpose S-100 board provides your computer with the most needed system support functions - at less cost than buying numerous single function boards. Includes sockets for 4K of extended address EPROM or RAM (2716 pinout), 1 socket with battery backup; crystal controlled month/day/year/time clock with BCD outputs; optional high speed math processor (9511 or 9512); full RS-232 serial port; three 16 bit interval timers (cascade or use independently); two interrupt controllers service 15 levels of interrupts; power fail indicator with provision to switch CMOS memory to battery backup; and comprehensive owner's manual with numerous software examples. Conforms fully to all IEEE 696/S-100 standards.

Want to make your S-100 system more versatile? System Support 1 is the answer. (Add $195 to the above prices for the optional 9512 math processor.)

NEW LOWER PRICE ON 16K MEMORY EXPANSION-8 RAMS/$35

Just what you would expect from the memory leader: top quality, low power, high speed (200 ns) 16K dynamic RAMs, backed up with a 1 year limited warranty. Expand ■ memoryinTRS-80*-l,.|land -III computers (Color model too) as well as machines made by Apple, Exidy, Heath H89, newer PETs, etc. Add $3 for two dip shunts plus TRS-80* conversion instructions. Limited quantity.

S-100 HIGH PERFORMANCE

MOTHERBOARDS

Actively terminated, fully shielded motherboards handle clock speeds up to 10 MHz. Unkits have edge connectors and termination resistors pre-soldered in place for easy assembly.

20 slot motherboard with edge connectors - Unkit $174, A/T $214 12 slot motherboard with edge connectors - Unkit $129, A/T $169 6 slot motherboard with edge connectors - Unkit $89, A/T $129

OTHER S-100 BUS PRODUCTS

Active Terminator Board $34.50 Kit

Memory Manager Board $59 Unkit, $85 A/T, $100 CSC

Mullen Extender Board $59 Kit

Mullen Relay/Opto-lsolator Control Board $129 Kit, $179 A/T

Spectrum color graphics board $299 Unkit, $399 A/T, $499 CSC

2708 EPROM Board (2708s not included) $85 Unkit, $135 A/T, $195 CSC

lnterfacerl(dual RS-232 serial ports) $199 Unkit. $249 A/T, $324 CSC

Interfacer 2 (3 parallel + 1 serial port) $199 Unkit, $249 A/T, $324 CSC

'LEGAL CORNER: ZBOA is a registered trademark of Zilog; TRS-80 is a trademark of the Tandy Corporation; PASCAL/M is a trademark ol Sorcim; CP/M is a registered trademark of Digital Research.

CompuProM

HIGH SPEED S-100 CPU BOARDS

8 BIT CPU Z

Like many others, we claim full conformance to IEEE 696/S-100 specifications; unlike many others, we'll send you the timing specs to prove it. CPU Z includes all standard Z-80A* features along with power on jump, on-board fully maskable interrupts for interrupt-driven systems, selectable automatic wait state insertion, provision for adding up to 8K of on-board EPROM, and 16/24 bit extended addressing. Works with 6 MHz CPUs; supplied with 4 MHz CPU. $225 Unkit, $295 A/T. $395 CSC.

16/8 BIT CPU 8085/88

Theonly board that bridges the 8 bit world of the present and the 16 bit world of the future. By using an 8088CPU (for 16 bit power with a standard 8bit bus) in conjunction with an 8 bit 8085, CPU 8085/88 is downward compatible with 8080/8085 software, upward compatible with 8086/88 software (as well a Intel's coming P-Series), designed for professional-level high speed applications, and capable of accessing 16 megabytes of memory. . .while conforming fully to all IEEE 696/S-100 standards (timing specs available on request).

Looking for a powerful 8 bit CPU board? Looking for a powerful 16 bit CPU board? Then look at CPU 8085/88, the best of both worlds.

Prices: $295 Unkit, $425 A/T (both operate at 5 MHz); $525 CSC (with 5 MHz 8085, 6 MHz 8088). Owner's manual available separately for $5.

8 BIT CPU 8085

This is a single 8 bit processor version of the above board, and may be easily upgraded to full 16 bit operation at a later date. $235 Unkit, $325 A/T, $425 CSC.

SOFTWARE

8088/8086 MONITOR-DEBUGGER: $35

Supplied on single sided, single density, soft-sector 8" disc. CP/M* compatible. Great development tool; mnemonics used in debug conform as closely as possible to current CP/M* DDT mnemonics.

PASCAL/M* FROM SORCIM: $175 COMPLETE

PASCAL - easy to learn, easy to apply - can give a microcomputer with CP/M" more power than many minis. We supply a totally standard Wirth PASCAL/M* 8" diskette and comprehensive manual. Specify Z-80* or 8080/8085 version.

S-100 MEMORIES

CompuPro memories feature fully static design to eliminate dynamic timing problems, full conformance to all IEEE 696/S-100 specifications, high speed operation (4/5 MHz Unkit, 10 MHz A/T and CSC), low power consumption, extensive bypassing, and careful thermal design.

Unkit A/T CSC

8K RAM 2A $159 $189 $239

16K R AM 14 (extended addressing) $279 $349 $429

16K RAM 20-16 (extended addressing and bank select) $319 $399 $479

24K RAM 20-24 (extended addressingand bank select) $429 $539 $629

32K RAM 20-32 (extended addressing and bank select) $559 $699 $799

128K RAM 21-128 (extended addressing) n/a n/a $2795

Most CompuPro products are available In Unkit form, Assembled/Tested, or qualified under the high-reliability Certified System Component (CSC) program (200 hour burn-in, more). Note: Unkits are not Intended for novices, as de-bugging may be required due to problems such as IC infant mortality. Factory service Is available for Unkits at a Hat

service charge.

TERMS: Prices shown do not Include dealer Installation and support services. Cal res add tax. Allow al least 5% shipping; excess refunded. Orders under $15 add $2 handling. VISA® and Mastercard® orders ($25 min) call our 24 hour order desk at (415) 562-0636. Include street address for UPS delivery. Prices are subject to change without notice.

FREE CATALOG: Want more information? Then'send for our free catalog. For fast 1st class delivery, add 41 cents in stamps; foreign orders add $2 (refundable with order).

division of

'ELECTRONICS"*

OAKLAND AIRPORT, CA 94614 (415) 562-0636

COMPUPRO PRODUCTS ARE AVAILABLE AT COMPUTER STORES WORLD-WIDE. . .CALL (415) 563-0636 FOR THE STORE NEAREST YOU.

Circle 141 on inquiry card.

SPECTACULAR OFFERS

BASF "FLEXYDISK"... *'

Superior Quality data .,.

storage medium. ymfl>

Certified and guaranteed | Wj

100% error free. ^*—' ■■

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5Va" or 8" Diskettes 10/$24

5W or 8" Vinyl Storage Pages 10/$5

MAXELL-DISKETTES The best quality diskette money can buy. Approved by Shugart and IBM. Sold only in boxes of 10

5", 1 side $3.30

B", 1-side $4.25

5", 2-side $3.90

8", 2-side $5.60

ALL MAXELL DISKETTES ARE DOUBLE DENSITY

LIBRARY CASE...

3-ring binder album. .

Protects your valuable '

programs on disks

Fully enclosed and

protected on all sides.

Similar to Kas-sette storage box.

Library 3-Ring Binder $6.50

5Va" Mini Kas - sette/10 $2.49

8" Kas-sette/10 $2.99

DISKETTE DRIVE HEAD CLEANING KITS—--— g Prevent head crashes and ^^™™C

insure efficient, errorfree operation.

5Va" or 8" $19.50

SFD CASSETTES

C-10 Cassettes 10/$7

(All cassettes include box & labels) Get 8 cassettes,C-10 sonic and Cassette/8 library album for

only $8.00

(As illustrated)

HARDHOLE

Reinforcing ring of

tough mylar protects

disk from damage

8" Applicator $4 5V<" Applicator $3

50/8" Hardholes $8 SVa" Hardholes $6

VISA • MASTERCHARGE • MONEY ORDERS CERTIFIED CHECK • FOR PERSONAL CHECKS ALLOW TWO WEEKS • CO.D. REQUIRES A 10%

DEPOSIT • CAL. RES. ADD 6% SALES TAX

MIN $2 SHIPPING & HANDLING • MINIMUM

ORDER $10 • SATISFACTION GUARANTEED

OR FULL REFUND

Write for our free catalog

ABM

PRODUCTS

631 B ST.

SAN DIEGO, CA 92101

(714)235-6602

Technical Forum.

Listing 2 continued: 9007 317A90 LXI

MAIN: 900A 215190 LXI

SP.STKTOP

;SET UP LOCAL STACK

H.PMODE ;THIS PUTS QUME IN PROGRAM MODE 900D CD4190 CALL SCAN ;READ SERIES LINE AND SEND

IT

TAB0: ;ACTUAL MESSAGE LOAD BEGINS HERE

9010 B7

9011 1E0A

TAB1: 9013 215790 9016CD4190 9019 216090 901C CD4190

ORA A ;CLEAR FLAGS

MVI E.NUMTBS ;SETS FOR CARRIAGE WIDTH

LXI H.TAB8SP

CALL SCAN

LXI H,SETTAB CALL

A>asm qtab.aaz

CP/M ASSEMBLER — YER 1.0

907A

003H USE FACTOR

END OF ASSEMBLY

A > type qtab.hex

1090000021000039226890317A90215190CD419011 10901000B71E0A215790CD4190216090CD41901DFF 10902000C21390215490CD4190216390CD41903155 109030006890C30000DBF8E680CA3590C979D3F99F 10904000C9B77EFE24C84FCD3590CD3D9023C34196 10905000901B0E241B0F24202020202020202024C1 069060001B31240D0A245F 0090000070

A>ddt qtab.hex SID VERS 1.4 NEXT PC END 9066 9000 677F #g0

A>b:

B> basic dataline

BASIC Rev. 5.1

[CP/M Version]

Copyright 1977, 78, 79, 80 (C) by Microsoft

Created: 14-Jan-80 5595 Bytes free

—MACHINE CODE / DATA LINE WRITER—

Enter hex base address of object code 9000 Routine length in 64-byte segments 2 Enter name of data statement file bytes.dat Enter line number of starting data statement 5000 5000 DATA 33, 0, 0, 57, 34, 104, 144, 49 5010 DATA 122, 144, 33, 81, 144, 205, 65, 144 5020 DATA 183, 30, 10, 33, 87, 144, 205, 65 5030 DATA 144, 33, 96, 144, 205, 65, 144, 29 5040 DATA 194, 19, 144, 33, 84, 144, 205, 65 5050 DATA 144, 33, 99, 144, 205, 65, 144, 49 5060 DATA 104, 144, 195, 0, 0, 219, 248, 230 5070 DATA 128, 202, 53, 144, 201, 121, 211, 249 5080 DATA 201, 183, 126, 254, 36, 200, 79, 205 5090 DATA 53, 144, 205, 61, 144, 35, 195, 65 5100 DATA 144, 27, 14, 36, 27, 15, 36, 32 5110 DATA 32, 32, 32, 32, 32, 32, 32, 36 5120 DATA 27, 49, 36, 13, 10, 36, 0, 0 5130 DATA 0, 0, 0, 0, 0, 0, 0, 0 5140 DATA 0, 0, 0, 0, 0, 0, 0, 0 5150 DATA 0, 0, 0, 0, 0, 0, 0, 0 OkB

222 March 1981 © BYTE Publications Inc

MORE BANG

Qantex Impact Printers

150 Characters Per Second

136 Columns Per Line

The microprocessor controlled Series 6000 is packed with standard features. True lower case descenders and underlining. Bidirectional logic seeking. Built-in test capability. Rugged 400 million character print head. Beautiful 96 character set in a 9x9 matrix. Parallel, or up to 19,200 baud serial interfaces supporting RS-232, X-ON, X-OFF or Current Loop. Full operator controls. Quietized, sleek enclosure to enhance your system. Delivery from stock.

Qantex

Division of North Atlantic Industries

60 Plant Avenue, Hauppauge, N.Y. 11787

(516)582-6060 TWX 510-227-9660

(800) 645-5292

For more information call your local distributor:

ARIZONA Tempe

Qualtech 602-967-4655

LOUISIANA New Orleans

Micro Computer Of New Oreleans 504-885-5883

AUSTRALIA BELGIUM CANADA FAR EAST FRANCE

Sydney Brussels Toronto Hong Kong Equipment Paris

Mitsui Computer Systems Compudata Belgium Computer Markets 5-453870 Gepsi

02-9299921 7205066 416-445-1978 1-554-9742

CALIFORNIA Inglewood

Basic Systems 213-673-4300

MINNESOTA Edina

Integrated Peripherals 612-831-0349

CALIFORNIA San Diego

Basic Systems 714-268-8000

MINNESOTA St. Paul

Vikeland Sales 612-645-4647

CALIFORNIA Santa Clara

Basic Systems 408-727-1800

MISSOURI Independence

Computer Dataco 816-254-3600

ILLINOIS Addison

Engineered Sales 312-832-8425

MISSOURI St. Louis

ESC Sales & Leasing 314-997-1515

GERMANY Munich

Technitron 49(89)692-4141

Distributor inquiries welcome!

Circle 142 on inquiry card.

INDIANA So. Bend

Audio Specialists 219-234-5001

NEW MEXICO Albuquerque

Qualtech 505-255-6100

THE NETHERLANDS

Compudata Benelux B.V. 73-215700

BYTE March 1981 223

Technical Forum

Addition and Subtraction: The 1802 Versus the Z80

Stephen Merrin, 4470 NW Alpha PI, Apt 6, Corvallis OR 97330

Binary arithmetic is inherently simple because it involves only 0s and Is. But recently, while I was trying to understand the instruction sets of two very different microprocessors, the 1802 and the Z80, I became confused when examining addition and subtraction operations. The confusion arose primarily over the notion of "borrow" in subtraction.

When you perform multiple-byte additions and subtractions, instructions like ADD WITH CARRY and SUBTRACT WITH BORROW (CARRY) are needed. In the 1802 User Manual the instruction SUBTRACT MEMORY WITH BORROW is defined as performing the following:

D - M(R(X)) - (NOT DF) - DF,D

Here, 8-bit arithmetic is being performed. DF is the borrow (carry) bit and M(R(X)) and D are 8-bit operands. On the other hand, in the Z80, you have the instruction SBC s, SUBTRACT WITH CARRY, which accomplishes:

A - A - s

CY

This operation involves the 8-bit operands A and s, and CY is the borrow (carry) bit.

If you are a programmer at the assembly- or machinelanguage level, you are aware that ambiguity in the description of the instruction set cannot be tolerated. You need to know such things as: Is the 1802 DF bit 0 or 1 if the result of subtracting two positive numbers is negative? Is the Z80 flag CY 0 or 1 if the result of subtracting two positive numbers is negative? (Oddly enough, even though CY and DF serve the same purpose in both microprocessors, the answer for the 1802 is opposite that of the Z80.)

My objective for this exercise was to explain to myself exactly what was happening at the bit level during these addition and subtraction operations. I also wanted to formulate a simple model of the operation. As it turned out, in the 1802, all addition and subtraction operations are very neatly and cleanly lumped into one category. In the Z80, however, the picture is not so simple. While the Z80 has a large and powerful instruction set which I prefer to that of the 1802, the 1802 has a certain elegant simplicity.

What I wanted to do was to first set up a model for binary addition and subtraction, without reference to any particular processor, then show how the 1802 and Z80 addition and subtraction operations could be inter

preted in terms of my model. I wanted my model to reflect the inherent simplicity that I ascribed to binary arithmetic.

In addition to 8-bit arithmetic operations, the Z80 also allows for 16-bit and even 4-bit operations, the latter being used in BCD (binary-coded decimal) manipulations (the half-carry flag H is the analog of the other carry flag CY). In the 1802, except for incrementing and decrementing the 16-bit registers R(N), all arithmetic operations use 8-bit operands. In my model, I am concerned only with 8-bit operations and how they can be used to implement multiple-byte additions and subtractions.

A unified model for addition and subtraction is possible because a subtraction operation can actually be viewed as an addition operation. Addition and subtraction can be accomplished with the same hardware, provided there are circuits to do complementation.

Let X and Y be 8-bit quantities. Y will denote the one's complement of Y ( Tis again an 8-bit quantity, obtained by replacing each 1 with a 0 and each 0 with a 1). Let c,- and c„ denote 1-bit values, called respectively "carry in" and "carry out." In my general model, all 8-bit additions and subtractions take the form:

X + Y + c,~ c„SUM

Here, SUM is the 8-bit quantity resulting from the addition of X, Y, and c,. If a carry is generated, then c0 = 1; otherwise c„ = 0. This is shown in figure 1.

For single-precision (1-byte) additions and subtractions, c, = 0 for addition and c, = l for subtraction. For multiple-byte operations, cf will take on the value of c„ generated in the last performed operation. The results of an addition or subtraction will be in two's complement form. The 8-bit quantity Y+l (and throw away the carry, if there is one) is the two's complement of Y.

If you wish to add X and Y, you do X+Y+Ci with c,=0; if you wish to compute the difference X—Y, you do X+ Y + Ci with c, = l (ie: add the two's complement of Y to X). Thus, as advertised, both the sum and difference of X and Y can be regarded as taking the form of an addition. The distinction is that, for subtraction, c, has a different value and the one's complement Y is used. Some examples are shown in figure 2.

The following is how multiple-byte sums are done. Suppose we have X = Xm,X„,.,...Xi (an m-byte sequence) and Y=Ym,Ym-u..Yl, where each Xk and Y„ is 8 bits. Let's say that you want to compute the multiple-byte sum X+ Y. You first perform Xi +Yi + c, with c, = 0. Then do

224

March 1981 © BYTE Publications Inc

Let onComptrting be your guide to personal compuf'

Finally* there is a

magazine that __ speaks to the beginner.

onComputing is the new McGrawHill quarterly that tells what's ahead — without talking over your head — in the 1980's with personal computers.

onComputing puts you on target with all the applications that go beyond your imagination.

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□ The list goes on and on in onComputing. If you're a beginner with personal

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onComputing

7B31 onComputing Subscription Dept. P.O. Box 307, Martinsville, NJ 08836

DOMESTIC subscription rate:

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©onComputing, Inc. 1981

Technical Forum

X

Y

+

H

E

SUM

Figure 1: A pictorial model of the addition of X, Y, and c. to give SUM and the carry bit

X2 + Y2 + C, where ct = c0 of the previous sum. And so forth until you finally do Xm + Y„ + c,, with cL = ca resulting from the immediately preceding sum of Xm-t and

Multiple-byte subtractions are similar. Again, suppose X and Y are given as above, but now you want to compute the multiple-byte difference X — Y. First, perform Xi + Y.+c, with c, = l. Next do X2 + Y2 + c, with ct = c0 of the preceding sum; and so on until you finally do X„-f-Ym-r-c, with Ci = c„ resulting from the immediately preceding sum of Xm-t and Ym_i. Notice that X—Y is computed by adding the two's complement of Y to X in a multiple-byte fashion.

Let me summarize the addition/subtraction model I have just presented. Whether you choose to add or subtract, or whether you want multiple-byte or single-byte operations, in all cases the fundamental operation is a sum of the form X+Y+c.-c, SUM.

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X = 5

Y = 6

Find X + Y

00000101

00000110

+ 0

X Y c,

00001011

X + Y

co = 0

X = 5

Y = 6

Find X-Y

00000101

X

11111001

Y

+ 1

c,

11111111

X

c = o

X = 6

Y = 5

Find X-Y

00000110

X

11111010

Y

+ 1

c,

Figure 2: Some examples of a unified model for binary addition and subtraction, c. and i

co are 1-bit values called "carry in" and "carry out." If a carry is generated by the addition of X and Y, then c

' o

= 1; otherwise c0 = o.

00000001 c0= 1

X-Y

The 1802 processor fits this model perfectly. In the 1802, both c, and c„ correspond to the 1-bit register DF. Just before the addition or subtraction operation is performed, DF is the c,. Just after the operation, DF is loaded with c0. (Incidentally, table 1 is a complete list of the 1802 arithmetic operations.) WITH CARRY and WITH BORROW operations take c, to be whatever value that currently resides in DF (ie: c, is determined by ca of the previous operation). Otherwise, as discussed in my model, c, must be 0 for an addition and 1 for a subtraction operation.

Table 1 is important for two reasons. First, it reveals exactly what each operation does. (D + M(R(X)) + DF-DF,D is much clearer than D-M(R(X))-(NOT DF) —DF,D.) Second, it is obvious that, without exception, each addition and subtraction operation has the form X+Y-f-c,— c„,SUM. This last fact is no accident, since (presumably) the same hardware is used for all operations.

In the Z80, the 1-bit carry flag CY serves the same function as the DF flag does in the 1802. In contrast with the 1802, where the DF bit corresponds exactly with the model's c, and c„, there is a distinction in the Z80 between an addition and a subtraction as far as the role of the CY is concerned. Consider this example that points out this distinction. Is the computation 5 — 3 the same as 5+ ( — 3)7 That is, in the Z80, is there any difference in the outcome between the assembly-language sequences (LD A,05 SUB 03) and (LD A,05 ADD FD)7 (FD is the two's complement representation of —3, written in hexadecimal.) While the end result is 02 in A for both computations, the final value of CY is not the same. When you do 5-3, CY = 0. When you do 5 + (-3), CY = 1. If you do analogous operations in the 1802, DF = 1 in both cases. How do you make sense out of all this?

Table 2 describes what occurs within the Z80 in terms of my model. Four classes of operations are shown in the table: add, add with carry, subtract, and subtract with carry. X and Y are arbitrary 8-bit operands within the

226 March 1981 © BYTE Publications Inc

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BYTE March 1981

227

Technical Forum

Operan

ds

Used That Match

Operation

the

Formula:

Operation

Code

X

+

Y

+ c,-c„,SUM

ADD

F4

M(R(X))

+

D

+

0-DF.D

ADD IMMEDIATE

FC

M(R(P))

+

D

+

O-DF.D

ADD WITH CARRY

74

M(R(X))

+

D

+

DF-DF.D

ADD WITH CARRY IMMEDIATE

7C

M(R(P))

+

D

+

DF-DF.D

SUBTRACT D

F5

M(R(X))

+

D

+

1-DF.D

SUBTRACT D IMMEDIATE

FD

M(R(P»

+

D

+

1-DF.D

SUBTRACT D WITH BORROW

75

M(R(X))

+

D

+

DF-DF.D

SUBTRACT D WITH BORROW IMMEDIATE

7D

M(R(P»

+

D

+

DF-DF.D

SUBTRACT MEMORY

F7

D +

M(R(X))

+

1-DF.D

SUBTRACT MEMORY IMMEDIATE

FF

D +

M(R(P»

+

1-DF.D

SUBTRACT MEMORY WITH BORROW

77

D +

M(R(X))

+

DF-DF.D

SUBTRACT MEMORY WITH BORROW IMMEDIATE

7F

D +

M(R(P))

+

DF-DF.D

Table 1: Arithmetic operations

of the 1802 microprocessor

Operation

X + Y

X - Y

performed

X + Y with carry

X - Y with carry

Equivalent

CY-0

CY-0

sequence of

steps taken

C-CY c-CY

C— CY c.-CY

within the

SUM=X + Y + c, SUM=X + Y + c

SUM=X+ Y +c, SUM = X+ Y + c,

Z80 to perform

CY-c„ CY-c„

CY- cT CY- c7

the given

operation

Table 2: Addition and subtraction operations in

the Z80 microprocessor.

No More Puns

From BD Software, available 'through Lifeboat Associates for a measly j145. While this compiler is only a subset of the incredible Unix* C, it is a subset designed to fit comfortably on CP/M systems and be maximally useful for non-number-crunching applications; i.e., thereare no inherent floating point or long variable types. You do get: fast and reasonably short object code, quick '^compilation and linking, powerful hooks into CP/M, plus plenty of docs and ^sample programs. —^r~°0

kTry it and . . . er, ahem

you know.

Unix is 3 trademark ol Bell Laboratories.

CP/M is a trademark ol Digital Research.

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Z80. Notice that the "with carry" operations (ADC, SBC) are distinguished from the others only in that CY is not initially zeroed. The peculiar feature of table 2 (in comparison with table 1) is that, when doing a subtraction, the CY bit is complemented beforehand to obtain c,. Following the operation, c„ is complemented to yield the final value for CY. This explains why 5—3 and 5 +(—3) are not equivalent in the Z80 (as far as the end result of CY is concerned). When the operation performed is a subtraction, CY takes on the complement of c0.

As an illustration of the importance of the above considerations, suppose that you want to compute X—Y (where X and Y are 8-bit positive values). Then you want to branch according to whether the result is negative or positive. In the 1802, DF = 1 means that the result was positive, and a branch is made based on the value of DF. Suppose in the Z80 you wish to branch according to CY (the branching could also be done according to the sign bit; however, there are cases when using CY is more convenient, such as a shift operation that follows a subtraction). The problem is not so straightforward now, because in the Z80, it is crucial to know whether or not X — Y was computed using a subtraction operation. If so, flag CY = 0 means the result was positive. ■

Technical Forum is a feature intended as an interactive dialog on the technology of personal computing. The subject matter is open-ended, and the intent is to foster discussion and communication among readers of BYTE. We ask that all correspondents supply their full names and addresses to be printed with their commentaries. We also ask that correspondents supply their telephone numbers, which will not be printed.

228

March 1981 © BYTE Publications Inc

Circle 145 on inquiry card.

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52

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Are you envious of all the people on your block who have their own microcomputer systems with fancy displays, sound effects, and all sorts of goodies? You needn't feel inferior any more. With the Hewlett-Packard HP41C programmable calculator, you can do all these things by considering the display to be a one-lire video display with 12-character capability. It will prompt you, make different-frequency sounds, and scroll its alphanumeric display.

You have probably played the popular Hunt the Wumpus game (in BASIC) on a microcomputer system. Now, you can hunt him on your HP-41C. This version of Hunt the Wumpus has all the excitement of the big game, including the ability to throw gas cans, get snatched by bats, or fall into a pit. You'll also be warned when the Wumpus, a pit, or bats are near.

The program will easily fit into an unexpanded HP41C. With added memory modules and a bit of ex

perimentation, many refinements are possible.

Playing the Game

After entering the program as shown in listing 1 (on page 232), set the following:

• SIZE 018 (eighteen registers are used)

• FIXO

• Enter the register data as shown in table 1

• ASN WUMP XEQ (assigns program to XEQ key)

• Put HP-41C in USER mode

• Press XEQ

At this point, you will be prompted with "SHOOT?" Enter your choice, YES or NO (you will automatically be in the ALPHA mode), and press RUN. You will be asked which room you wish to enter. Continue until you win or lose. Happy hunting! ■

LSI-11 SYSTEMS FROM ANDROMEDA

Any size you want.

No matter what your LSI-11 system needs are, Andromeda can satisfy them.

For example, the 11/M1 system shown on the right weighs only 14 pounds yet contains 102kb of mini disk storage

(expandable to 389kb), 64kb of RAM, space for up to 16kbof EPROM, 4 serial ports, and the LSI-11/2 CPU. All of this for less than $4000. While the 11/M1 will run the RT-11 operating system, it is best suited fordedicated applications where its small size but large processing power are needed.

Near the other end of the scale is the 11/H23-DDF system shown at the left. The mobile enclosure includes the LSI-11/23 processor, 256kb main memory, 10mb of storage onthedouble density RK-05 cartridge disk and 1.2mb on the double density floppy disks. This system also has 4 serial ports and 7 empty dual width slots for additional interfaces. The $22,500 price includes the video terminal shown, a 150 CPS matrix printer, and the RT-11 operating system.

These are just two examples of the many LSI-11 based systems available from Andromeda. And the standard systems are just starting points; we will provide any combination of pack

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LSI-11. RT-11, and RK-05 are trademarks of the Digital Equipment Corp.

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Prices are domestic U.S.A. only.

230 March 1981 © BYTE Publications Inc

Circle 147 on inquiry card.

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CP/M Is a registered trademark of Digital Research, Inc.

Circle 148 on inquiry card.

BYTE March 1981 231

Circle 149 on inquiry card.

The

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IHgLii/ermore

Ihm DATA SYSTEMS INC. 2050 Research Drive, Livermore, CA 94550

232 March 1981 © BYTE Publications Inc

Desk-Top Wonders.

Register

Contents

Comments

R0

_

Your location, generated randomly

R1

2345 "

R2

158 10

R3

1467

R4

1357

R5

124 10

>

Room layouts, enter these values

R6

3789

in ALPHA mode

R7

3469

R8

269 10

R9

678 10

R10

2589

R11

3

Number of cans of gas, generated by program

R12

seed

Used for random number generation 0<s<1

R13

_

Wumpus position

R14

—

Bat positions (all generated randomly)

R15

—

Pit position

R16

YES

Enter letters in ALPHA mode; used for string comparison

R17

NO

Enter letters in ALPHA mode; used for string comparison

Table 1:

Register data used

in the Hunt the Wumpus game for the HP-41C. A dash

indicates data that varies from game to game. See the text for details on using the

program

Listing 1: Hunt the Wumpus for the HP-41C programmable calculator.

Si*LBL "viUr-lP"

38 X<=Y?

75 'V CANS'

112 GTO 89

82 3

39 GTO 95

76 RVIEH

113*LBL 32

83 STG 11

48 "WUMPUS NEAR'

77 PSE

114 "FELL IH

H4 X£y 9;

41 RVIEH

78 "SHOOT?"

ll 5 RVIEH

95 STG i3

42+LBL 85

79 ARCL 16

116 STOP

86 XEQ "I

43 RCL 14

88 "r-"

117+LBL 13

87 STO 14

44 XEQ 86

81 ARCL 17

118 "TO ROOM:

98 XEQ 91

45 X<=Y?

82 RVIEH

119 ARCL IHD 88

89 STO 15

46 GTO 87

83 PSE

128 AVIEH

18+LBL 93

47 "BATS HEAR"

84 RON

121 PSE

11 XEQ 91

43 RVIEH

85 STOP

122 RTH

12 RCL 13

49*LBL 87

86 ASTO X

123+LBL 86

13 X=Y?

58 RCL 15

87 AOFF

124 1

14 GTG 99

51 XEQ 86

88 RCL 16

125 ST- 11

15 XOY

52 X<=Y?

89 X=Y?

126 XEQ 13

16 STO 69

53 GTO 14

96 GTG 68

127 STOP

17+LBL 89

54 "PIT NEAR"

91 XEQ 13

128 STO 88

18 XEQ 93

55 AVIEH

92 STOP

129 RCL 13

19 GIG 92

56 GTO 14

93 STO 88

136

28 GTG 14

57*LBL 66

94+LBL 84

131 X=8?

2ULBL 91

58 RCL m

95 RCL 88

132 GTO 18

22 RCL 12

59

96 RCL 14

133 RCL 11

23 PI

68 ABS

97

134 X=8?

24 ♦

61 3

98 X=8?

135 GTO 15

25 21

62 RTH

99 GTO 11

136 "HISSED"

26 *

63*LBL 83

188 RCL 88

137 AVIEH

*57 rn,

u rr-.L

64 RCL 89

181 RCL 15

138 GTO 99

28 STG 12

65 "YOU ARE IN ROOM"

162

139+LBL 18

29 19

66 "h HO:"

183 X=8?

148 "GOT Hlh"

36 *

67 ARCL X

184 GTO 12

141 AVIEH

31 IHT

68 RVIEN

185 GTO 69

142 BEEP

32 i

69 PSE

186+LBL 11

143 STOP

33 +

78 PSE

187 XEQ 81

144+LBL 15

34 RTH

71 RTH

188 STO 88

145 "LOST"

35+LBL 92

72*LBL 14

189 "SNATCHED TO."

146 AVIEH

36 RCL 13

72 "GOT"

118 ARCL 88

147 TONE 1

37 XEQ 86

74 ARCL 11

111 RVIEH

148 END

Circle 150 on Inquiry card.

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Technical Forum

Build a Simple Video Switch

Richard C Hallgren, Department of Biomechanics,

College of Osteopathic Medicine, Michigan State University,

East Lansing MI 48824

Although I know that there are many sophisticated ways of building a video switch, I am hard pressed to think of one that is easier to build, as inexpensive, or works as reliably as mine. In the process of building a CAI (computer-aided instruction) system, I needed a logic-controlled device to switch video to a video display at appropriate times. Because I had to transfer the video signal without excessive attenuation, I knew that the switch required a series impedance of less than 50 ohms at 10 MHz.

Motorola Semiconductor manufactures a quad bilateral switch (MC14016B) that is able to transfer frequencies up to 54 MHz, but the series resistance of each switch is in the neighborhood of 300 ohms. As I considered other alternatives, it occurred to me that if I took two of the devices and connected all eight of the switches in parallel, the series impedance would be approximately 37.5 ohms.

Figure 1 shows the schematic diagram of the video switch. Dropping the control line to ground opens the switch, and raising the control line to +5 V closes the

Quad Analog Switch/Quad Multiplexer

• High on/off output voltage ratio — 65 dB typical

• Quiescent current = 0.5 nA/package typical at 5 VDC

• Low crosstalk between switches — 80 dB typical at 1.0 MHz

• Diode protection on all inputs

• Supply voltage range = 3.0 VDC to 18 VDC

• Transmits frequencies up to 54 MHz at 5 VDC

• Linearized transfer characteristics

• Low noise — 12nV/\/Cycle, f > 1 kHz typical

• Pin-for-pin replacement for CD4016, CD4066

Maximum Ratings (voltage referenced to Vss)

Rating

Symbol

Value Unit

DC supply voltage

Vdd

-0.5 to +18 VDC

Input voltage—all inputs

vin

-0.5 to VDD+0.5 VDC

DC current drain per pin

1

10 mADC

Operating temperature range AL device CL/CP device

TA

-55 to + 125 °C - 40 to + 85

Storage temperature range

Tstg

-65 to +150 °C

Table 1: Technical data for th

e MC14016B.

switch. Since the units are bilateral, it doesn't matter which line is the input or output. I have used the switch in this form for over a year, and it has performed so well that there hasn't been a need to replace it with a more elegant design. ■

VIDEO IN/OUT

Ot

VIDEO OUT/IN

o

VIDEO/

CONTROL

GROUND

C^

+ 5V A

MC14016B Nl VCC

01 02 IN2 C2 C3 GROUND

CI C4 IN4

04 03 IN3

10

CONTROL O

MC14016B INI VCC

01

02

IN2

C2

C3

GROUND

CI C4

IN4 04 03

IN3

14

13

Figure 1: Schematic diagram of a simple video switch. The MC14016B integrated circuit is a Quad Analog Switch/Quad Multiplexer manufactured by Motorola Semiconductor.

234 March 1981 © BYTE Publications lnc

DEALERS: By now you know that it takes

SOFTWARE

TO SELL

COMPUTERS

and International Micro Systems can provide you with the largest selection of quality business applications ever developed for the microcomputer industry.

If you are just looking for a G.L., A/P, and Payroll, you can find them in a dozen ads in this magazine. But thers'sa much bigger market for micros out there than that. Where can you find a fully interfaced Wholesale/Retail Distribution System? How about Manufacturing Inventory Control including Production Scheduling & Control. See that one anywhere else? Maybe your market is Medical/Dental and IMS has the full systems there too. You can't sell computers without software and IMS has the finest selection of software available foryou. Each system has been developed by the IMS professional staff and we support what we sell.

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Circle 151 on inquiry card.

BYTE March 1981

235

System Notes

Software Addressing Modes for the 8080

Dragan Bozinovic

25 Wood St Apt 810

Toronto, Ontario M4Y 2P9 Canada

If you have ever had to write a nontrivial program in Intel 8080 assembler, you probably missed the convenience of more sophisticated addressing modes such as indexed, indirect, and relative addressing. You may have also wished that you had an easy way to access data stored below the top of the stack.

Let's briefly review what Intel 8080 hardware offers in the area of addressing, along with suggestions for improvement:

1. Direct addressing: All 3-byte instructions are direct, with the absolute address stored in the last 2 bytes of the instruction. If you do not have a relocating assembler and loader, you must specify absolute starting addresses in your subroutines. This will force you to reassemble them whenever you have to change addresses. It would be convenient to have relative addressing instead, which would specify the displacement (positive or negative) of the referenced address relative to the address of the referencing instruction. Assemblers can easily calculate these displacements for you. All addresses in your subroutine will be independent of its starting location, allowing you to move the object code anywhere in memory. Relative addressing tends to confuse beginners, but they soon find that it is worth the effort to overcome the initial confusion.

2. Implicit addressing: Most instructions can reference the byte pointed to by the "data counter" (register pair HL), while a few accumulator-oriented instructions can use other registers as data counters. A nicer arrangement would be one in which any memory location could serve as a data counter, freeing the processor registers for more useful work. This is where indirect addressing comes in.

3. Stack pointer addressing: You can readily access the last 2 bytes stored in the stack, but if you think about retrieving bytes stored previously you may get a headache.

4. Immediate data: The instruction itself contains the data byte instead of an address.

What can software do to enhance the choice of addressing modes? If you're not overly concerned about execution speed, you may use software routines to create the illusion of having any addressing mode you desire. You will also need a few bytes of programmable (writable) memory.

How does it work? Just CALL the routine implementing the particular addressing mode, followed immediately by the instruction to be executed using that mode. That instruction will not be executed as is, but will provide the operation code and information necessary for EA (effective address) calculation. Instructions that are to be executed by hardware will be formed in programmable memory. After execution, control returns to the instruction following the pseudo-instruction unless it was a successful CALL or JMP. None of the registers are changed unless they are modified by the instruction to be executed.

Listing 1 contains detailed specifications of each routine and its source code. Concerning the programming conventions used, it may be noted that routines were developed using the Intel MAC80 assembler, which has only one location counter ($). To define data storage close to the routines that use it, and still separate it physically into programmable memory, three predefined labels, PROG, DATA, and TEMP, are used to keep track of the addresses.

The basic idea behind the approach described here is that of covering hardware by a layer of software routines, creating an illusion of a machine that is easier to program. In fact, this is the concept behind the creation of a virtual machine. It can be expanded far beyond the basic addressing modes, particularly in the area of I/O (input/output) handling. This approach was developed to hide peripheral devices from the programmer, but the application to addressing modes is likely to be better understood by a wider circle of programmers. ■

Listing 1 and text box on pages 238 and 240.

236 March 1981 © BYTE Publications Inc

Circle 152 on inquiry card.

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TECMAR, INC.

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System Notes

Listing 1: Sophisticated addressing modes may be emulated on an Intel 8080 microprocessor with the use of these subroutines. They are passed values interpreted as pseudo-code, each setting up the proper absolute addresses, freeing the programmer from the bind of limited addressing. Similar routines could easily be developed for other processors.

Location

Object Cods

Label

AODC

AODC

RELAT:

AODC

E3

AODD

FS

AODE

D5

AODF

CD27A1

A0E2

2B

A0E3

2B

A0E4

2B

A0E5

C31DA1

OOOC

LENGTH

A0E8

PROG

A0E8

*

A0E8

SPNDX:

A0E8

E3

A0E9

F5

AOEA

D5

AOEB

EB

AOEC

210600

AOEF

39

AOFO

EB

A0F1

D5

A0F2

C319A1

000D

LENGTH

A0F5

PROG

A0F5

*

A0F5

SPDEX:

A0F5

E3

A0F6

F5

A0F7

D5

A0F8

E5

A0F9

210800

AOFC

39

AOFD

E3

AOFE

CD39A1

A101

El

A102

C31DA1

0010

LENGTH

A105

PROG

A105

INDRX:

A105

E3

A106

F5

A107

D5

Operation

Operand

ORG

PROG

XTHL

PUSH

PSW

PUSH

D

CALL

EMSUB

DCX

H

DCX

H

DCX

H

JMP

EMEND

SET

S-RELAT

SET

$.

ORG

PROG

XTHL

PUSH

PSW

PUSH

D

XCHG

LXI

H,6

DAD

SP

XCHG

PUSH

D

JMP

EMI

SET

S-SPNDX

SET

$

ORG

PROG

XTHL

PUSH

PSW

PUSH

D

PUSH

H

LXI

Hr8

DAD

SP

XTHL

CALL

EMS1B

POP

H

JMP

EMEND

SET

S-SPDEX

SET

$

XTHL

PUSH

PSW

PUSH

D

A108

E5

A109

EB

A10A

5E

A10B

23

A10C

56

A10D

EB

A10E

E3

A10F

C319A1

000D

LENGTH

A112

PROG

A112

'

A112

INDEX:

A112

E3

A113

F5

AIM

D5

A115

D5

A116

C319A1

0007

LENGTH

A119

PROG

A1I9

A119

EMI:

A119

CD27A1

A11C

El

A11D

EMEND:

A11D

19

A11E

22F167

A121

Dl

A122

Fl

A123

El

A124

C3F0B7

A127

EMSUB:

A127

7E

A128

32F0B7

A128

23

A12C

5E

A12D

23

A12E

56

A12F

EMSBR:

A12F

3E

A130

C3

A131

32F387

A134

23

A135

22F4B7

A138

C9

A139

EMS1B:

A139

7E

A13A

32F0B7

A13D

C32FA1

0027

LENGTH

A140

PROG

B7F0

B7F0

EMINS:

B7F3

EMRTN:

B800

B800

DATA

PUSH

H

XCHG

MOV

E,M

INX

H

MOV

D,M

XCHG

XTHL

JMP

EMI

SET

S-INDRX

SET

$

ORG

PROG

XTHL

PUSH

PSW

PUSH

D

PUSH

D

JMP

EMI

SET

S-INDEX

SET

$

ORG

PROG

CALL

EMSUB

POP

H

DAD

D

SHLD

EMINS+ 1

POP

D

POP

PSW

POP

H

JMP

EMINS

MOV

A,M

STA

EMINS

INX

H

MOV

E,M

INX

H

MOV

D,M

DB

03EH

DB

0C3H

STA

EMRTN

INX

H

SHLD

EMRTN+ 1

RET

MOV

A,M

STA

EMINS

JMP

EMSBR

SET

S-EM1

SET

$

ORG

TEMP

DS

3

DS

3

ORG

DATA

SET

$

S2 SORCIM

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the SORCIM Report

the past three years, Sorcim's professionals have scored a string of software successes. These lude:

* PASCAL/M™, a complete implementation of the Wirth PASCAL language that supports the ISO standard.

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In the months to come, Sorcim will introduce additional software tools that will continue our tradition of excellence. If you're not already familiar with our products and services, you should be; write today for a free brochure that shows how Sorcim's cost-effective software lets you unlock the full potential of today's - as well as tomorrow's -. microcomputers.

Those of you who have already had a chance to experience the versatility and trouble-free operation of Sorcim products will be delighted to see what we'll be introducing in the future. Watch for our upcoming ads - there are more software success stories yet to come.

Sorcim is the source for microcomputer software tools.

238 March 1981 © BYTE Publications Inc

Circle 153 on inquiry card.

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Phone: 216/526-0838 / 526-0839 Telex: 241596

Circle 154 on inquiry card.

BYTE March 1981 239

System Notes

Interface Specifications

Family: EMUL

Routines: RELAT, INDEX, INDRX, SPNDX, SPDEX.

Purpose: This family of routines EMULates several addressing modes not implemented by Intel 8080 hardware.

Description: Routines consist of separate CALLable prefixes of code, common subroutine (EMSUB), and final processing routine (EMEND), grouped under the name EMUL (see listing 1). Prefixes of unnecessary routines may be removed. All routines share a common temporary data area defined in EMUL. In this work area two instructions are constructed and executed:

1. Instruction to be emulated

2. Return jump

CALLing interface basic description:

CALL entry-point

op address-parameter

The instruction to be emulated is one of Intel 8080's 3-byte instructions: LDA, ST A, LHLD, SHLD, LXI, JMP's and CALLs. Any other instruction is illegal and will produce incorrect results. Return is made after the emulated instruction (except for JMP and CALL). The instruction is not executed as coded, but serves as an argument to emulation routines. The value expected in the address field of the emulated instruction and the method of forming EA as well as eventual additional parameters are all described for each routine. Some of the routines are redundant and can be simulated by others from this family. Users will have to decide which to use depending on the concern for programming convenience, calling sequence storage requirements, and execution speed. If applicable, alternate ways of accomplishing each effect are given under the description of each routine.

Side Effects: The current stack is used three to four words deep and restored before return. None of the processor registers are changed (including PSW) unless modified by the emulated instruction.

Routine: RELAT

Purpose: This routine is provided to facilitate writing of PIC (position-independent code). It emulates addressing relative to PC (program counter).

Use: // you are writing a module that must be capable of executing anywhere in memory you may reference a label in the same module as follows:

CALL op

RELAT label-S

The displacement label-$ will be added to the content of PC to form the effective address and the instruction will be executed. The only precondition is to have RELAT code or JMP to it on the fixed absolute address known at assembly time.

Routine: INDEX

Purpose: This routine emulates addressing relative to the content of the register pair DE. Effective address is formed as:

EA = (DE) + displacement

Displacement is taken from the address field of the emulated instruction and can be either positive or negative.

Routine: INDRX

Purpose: This routine emulates addressing relative to content of the word pointed to by register pair DE. Effective address is formed as:

EA = ((DE)) + displacement

Calling sequence:

LXI

CALL

D, address INDRX

is equivalent to:

LHLD

XCHG

CALL

address INDEX

Routine: SPNDX

Purpose: Sometimes you may wish to access not the top word o,f the current stack fosing POP, XTHL, or PUSH), but a previously stored word or byte. This may be accomplished by calling this routine if the position of the desired word or byte relative to the top of the stack is known at assembly time. The word that is referenced by POP is accessed using an offset of zero (low byte zero, high byte one). The offset is found in the address field of the instruction to be emulated. It is not and cannot be checked against the current depth of the stack. The SP content is not changed.

Routine: SPDEX

Purpose: This routine has the same purpose as SPNDX, but the offset is found in register pair DE instead of the address field of the following instruction. This permits the offset to be dynamically changed, even if the program is to be ROM (read-only memory) resident. The calling sequence of this routine is different from the general model. It is:

; $ being the current location counter value

LXI

CALL

DB

D,off set

SPDEX

op-code

or equivalent

octal

hex

240 March 1981 © BYTE Publications Inc

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BYTE March 1981

241

BYTELINES

News and Speculation About Personal Computing

Conducted by Sol Libes

•Software Copyright Law Enacted: Congress has passed the Computer Software Copyright Act of 1980. It protects the rights of individuals and companies who develop, sell, and lease computer programs. The law adds computer programs to the list of "writings" in which exclusive rights may be granted for "limited times," which generally is until 50 years after the author's death.

The law gives the author exclusive rights to copy the work and to transfer ownership rights, including sale and leasing arrangements. Piracy is punishable by fines, civil damages, or criminal penalties. Work does not have to be registered with the Copyright Office to be protected; it is protected once it is in "any tangible medium of expression."

Before the passage of this law, the copyright status of computer software was unclear.

■ Irst 68000 System

Introduced: S-100-bus personal-computer users can now step up to the most powerful 16-bit microprocessor—the Motorola MC68000. Management Analysis & Control Inc, 3530 C Street NE, Auburn WA 98002, is the first manufacturer to announce a 68000-based personalcomputer system. Its new processor card will sell for $2095. (That's more than I paid for my entire S-100 cabinet and contents!) As yet, no software has been announced.

iJhugart Offers

5 Megabyte Hard-Disk System For Under S2000: If you're looking for a hard-disk system and

can do some minimal interfacing, you'll be interested in Shugart Associates' special deal, called the "Success Kit." The kit is really an evaluation offer for OEMs considering the design of a Shugart hard-disk drive into their computer systems; however, there are no restrictions on the offer, hence anyone can buy just one Success Kit. For $1950 you can get an SA1002 8-inch, 5-megabyte Winchester-technology drive, an SA1400 intelligent controller, cables, and documentation. The controller provides backup on single- or double-sided floppy-disk drives. For more information, call (800) 824-7888; in California (800) 852-7777 (operator 12).

■ CC Grants Apple and Heath Extensions: The

FCC has granted Apple Computer Inc and Heath Company a 3-month extension on compliance with the January 1, 1981 deadline for RF (radio-frequency) radiation regulations. Each unit now carries a label warning that the equipment can interfere with radio and television reception and that the user is responsible for correcting it.

This is the second extension of the original July 1980 deadline given the companies by the FCC. Both contended that more time was needed to make the necessary product changes.

MtST Plans HomeVideo Data Base: AT&T has disclosed that it is about to begin a year-long test of an electronic telephone directory. The test will involve 700 color-video terminals in homes and businesses throughout Austin, Texas.

The terminals will be connected to telephone lines and used to access whiteand Yellow-Pages listings. Users will also be able to store personal information.

A similar test involving eighty-three participants was conducted earlier in Albany, Texas; it involved black-andwhite terminals. AT&T is conducting anothertestwith the Knight-Ridder Newspaper group, in Coral Cables, Florida. That system includes news reports, home banking, and a home-shopping service.

If these tests are successful, it will be three to four years before the system is widely available.

v apaneie Sales Of USMade Personal Computers Drop Sharply:

Feedback From Fujitsu, a Japanese computer-industry newsletter, reports that the sales of US-made personal computers in that country have dropped sharply. It says that until recently, Tandy/Radio Shack, Commodore, and Apple manufactured over 90% of the 6000 to 7000 personal computers sold monthly in Japan. However, their share of the market has fallen to 20% as Hitachi, NEC (Nippon Electric Company), and Sharp have moved into the manufacture and sale of personal computers.

Apple and Tandy have formed joint ventures with Japanese concerns in an attempt to combat these inroads on US sales. Commodore is reportedly studying a similar move.

vapanese Establishing Foothold In US Personal Computing: The Japanese presence is being felt in the American personal-comput

er market. For example, all 142 Computerland stores will soon carry Japanese personal computers. Computerland is currently negotiating with Casio, NEC, Panasonic, and Hitachi. Several other distributors are flirting with Japanese personal computers. Apple, Tl (Texas Instruments), and Atari appear to be the primary losers of valuable showroom space.

I ermlnals To Replace Phone Directories: The

French government is preparing to launch a bold effort to give every telephone subscriber in France a minivideo terminal. Initially it will provide on-line telephone directories. The terminal will have a 7-to 8-inch diagonal screen with 24 lines of 40 characters each, solidstate keyboard, and a modem to send data at 75 bps (bits per second) and receive at 1200 bps. The PTT (Postal Telephone and Telegraph Authority) expects the terminal to cost $75 to $100. Over the next ten years, the PTT expects to procure more than 30 million terminals at a cost of $3 billion, which it estimates is less than the cost of printed directories and directory-assistance operators.

M.

I ore Hobby Robotics Activities: Add these developments to previously listed sources of robotics information.

The United States Robotics Society, Palo Alto, California, is resuming publication of its ROVOX newsletter. Membership is $20 per year. The Computerworld Store, Van Nuys, California, has published the Robotics Catalog. Also, the International Institute of

242 March 1981 © BYTE Publications Inc

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-sectoi

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BYTE March 1981

243

BYTELINES

Robots in Pelahatchie, Mississippi, has resumed publication of its quarterly newsletter.

w

rlstwatch-Slzed Computer Proposed: Ten

years ago, who would have conceived of the table-top computer or, better yet, the pocket computer? Yet they are realities today. Current dreams envision something much smaller: the November 1980 Computer carried a detailed proposal by Stephen Kearney for a computer to be worn on your wrist. Kearney has overcome the I/O (input/output) problem with a clearly thought out display and keyboard. The LCD (liquid-crystal display) is 27 characters by 8 lines (for a total of 216 characters), with uppercase, lowercase, and special characters, in a space 1 % by 3 inches. The unit has a 9-key keyboard capable of upperand lowercase alphanumerics and special characters. The keyboard measures '/, inch by 2 inches.

w,

hlch Computer Is The Fastest?: Datamation recently conducted a survey to determine which computers are the fastest in production. The measurement used was KOPS (thousands of operations per second). This was felt to be a better measure than MIPS (millions of instructions per second). The top three were: Cray-1 (800,000 KOPS), CDC Cyber 205 (800,000 KOPS), and CDC 7600 (10,000 KOPS). The fastest IBM computer was the IBM 1088 (2X) with 1160 KOPS.

The KOPS rating is determined by measuring how long it takes the computer to execute a prescribed mix of programs; the measurement ignores I/O and operatingsystem considerations. As such, KOPS measures only processor speed and not system speed.

Jmart Wheelchair Shown: The Rehabilita

tion Engineering Center of the Veterans Administration Hospital, Palo Alto, California, has demonstrated a prototype microprocessorcontrolled wheelchair for severely incapacitated persons. Using autofocus ultrasonic-ranging detectors aimed at the head, a person can direct the wheelchair's movements by moving his head. Sensors are included to detect objects in the chair's path and to gauge distance to walls so that the chair can track a wall at a fixed distance. Cruise control is provided so that the user can relax until a change in velocity is wanted. The developers expect this unit to add only $100 to $200 to the cost of a standard wheelchair.

■ lat-Panel Display

Update: There are over 2 million video terminals in use. It's expected that yearly shipments will top the million-unit level by the mid-1980s. However, they have some big disadvantages. They're bulky, they waste a lot of desk space, consume too much power, annoy users with reflected light, and are damaged easily.

More than a dozen companies are developing flatpanel displays. Some are already in production. Most successful are the plasma displays. LCD and ELD (electroluminescent displays) are also being developed.

The Japanese are working on flat-panel displays. Fujitsu, Hitachi, Matsushita, and Seiko Denki have all produced plasma and LCD prototypes. Hycom Corporation, a US subsidiary of Sharp, has developed an ELD for the US Army in portable battlefield terminals. Exxon Corporation, through its Kylex and Electrophoretic Information Display divisions, is also developing flat displays. Kylex is already producing an 8-line LCD panel, and it is rumored that this will soon be expanded.

There is no doubt that by

the end of the decade flatpanel displays will dominate the terminal- and televisiondisplay markets. They will offer low power consumption, high daylight visibility, and the shock resistance necessary to make the true portable computer and intelligent terminal a reality.

^» an A Computer Have Worms7 Several years ago rumor had it that an enterprising computer hacker had gained access to a DOD computer from a remote terminal. Once inside, he entered a program that rewrote its data into all of the computer's memory, destroying the computer's software and data base. In other words, the program was like the shapeless monster from the classic science-fiction thriller, The Blob.

Now, from Xerox's Palo Alto (California) Research Center, comes the "Worm." The Worm is a series of programs that wiggles through a computer network at will, copying itself into inactive systems in the network. The Worm coordinates the operation of all the computer systems in the network. It delegates tasks to unused machines and coordinates the operation of machines in the network. Any complex computations are handled by harnessing multiple processors.

The Worm is still in the experimental stage. As such, it may be the precursor of much more powerful autonomous programs that, like the Blob, could take over and control entire networks.

Vomputer Contest To Aid The Handicapped:

The National Science Foundation, Johns Hopkins University, and Radio Shack have announced a nationwide competition for computer aids for the physically or mentally handicapped. (See "National Search to Aid the Handicapped Through Personal Computers," page 316.) The grand prize is

$10,000, with runner-up prizes of equipment and money. There are several incentives to encourage participation, including separate entry categories for students, amateurs, and professionals. For more information, contact Personal Computers for the Handicapped, Johns Hopkins University, POB 670, Laurel MD 20810.

R.

obot Destroys Itself:

An experimental robot at the University of Florida went out of control, destroying itself before a graduate student could press its cutoff button. The robot's arm was driven into its supporting body, ripping its shoulder off.

#«erox Introduces First Ethernet System: Xerox has been talking about Ethernet for two years, and I have reported on its progress many times. Finally, it has introduced the first system hardware. Called the Xerox System 8000, it allows users to create, file, print, and distribute documents and data to any and all users on the system. It allows many types of office equipment to be linked into an integrated local system via coaxial cable, and the system can be tied in to other external networks.

Without a doubt, many manufacturers will introduce hardware and software interfaces for the Ethernet system. IBM, Wang, Exxon, AT&T, and M/A-COM are working on their own local network systems.

I

BM Opens Retail

Stores: Philadelphia and Baltimore are the sites of IBM's two new storefront sales outlets. Several more are planned.

The stores carry typewriters, copiers, word processors, small-business computers, and supplies. IBM is following in the footsteps of

244 March 1981 © BYTE Publications Inc

TOMORROW'S answers for the H8 TODAY!

DG Electronic Developments provides the only enhancements to put the Heath " H8 ahead TODAY while maintaining its high standards, broad flexibility and high reliability.

DG-80 (Z80" Based CPU)

The DG-80 offers the BEST foundation for the H8 to build on for the future. Compare the DG-80 to your current Heath" 8080 CPU and see the advantages of the DG-80's superior speed and flexibility. The Z80 gives twice the processing speed coupled with twice the instruction set making your H8 a truly professional microsystem. DG-80 aids the efficient writing of utility programs, user routines, sub-routines and use of assemblers.

DG-80 $249. (Documentation only $25.)

DG-FP8/ADP4 (DG80 Front Panel Monitor)

The DG-FP8/ADP4 firmware/hardware package brings the world of standardization to your H8. The FP8/ADP4 allows the full use of currently available "STANDARD" CPM software, with 4 MHz operation. You can still use your HDOS and all its related software, by simply putting a disk in your drive. The DG firmware package gives you use of the full 64K of RAM available on the 64D or 64D5. The FP8/ADP4 firmware also offers many extras including hexadecimal O R split octal display; simplification of register and memory contents display; and the full use of all Z80 registers (more than twice the number of registers in the 8080). Plus, the unique front-panel single-step feature is maintained to aid in software troubleshooting. DG-FP8 $69.95. DG-ADP4 $19.95. Purchased together $79.95.

(Documentation only — source code not included $ 15.)

DG-64D (64K RAM Memory Board)

The DG-64D is THE BEST memory board available for the H8! Along with the DG-80 CPU, the 64D gives a full 64K of addressable memory. Its built-in flexibility ensures future compatibility. Multi-user configurations can be achieved accessing up to eight 64D's on line with the hardware/software bank select features. Memory contents are maintained and protected during extended wait states by asynchronous refresh.

DG-64D priced from $333 (0K) to $529 (64K). (Documentation only $15.)

DG-64D5 (5-Volt Power Supply 64K RAM)

The DG-64D5 memory board offers the ultimate in low power consumption for the H8 computer! The 64D5 is primarily designed for use with the Heath Color Graphics board. In addition to offering ALL of the features of the standard 64D, the 64D5 utilizes single-supply 5-volt-only dynamic RAMs and allows the use of extended wait states.

Priced from $333 (0K) to $799 (64K). (Documentation only $15.)

Chip Sets (8-4517 dynamic RAMS) $ 150.

CP/M (Standard V2.2 Disk Operating System)

The final component for the "STANDARD" H8 system is Digital Research's CP/M " V2.2. Our full line of H8 enhancements in combination with CP/M gives the user unparalleled flexibility and puts thousands of CP/M software programs at your fingertips.

CPM V2.2 $ I 30. (Documentation only $25.)

All products supplied with complete documentation. Please call or write for additional information.

Heath' and H8" are registered trademarks ot Heath Corporation. Benton Harbor. Michigan. CP/M- is the registered trademark of Digital Research ot Pacific Grove. California. Z80 ■ is the registered trademark of Zilog Corporation.

D-E

Ordering Information: Products listed available from DG Electronic Developments Co., P.O. Box 1124. 1827 South Armstrong, Dentson, Tx. 75020. Check, Money Order, VISA or MasterCard accepted. Phone orders (charge only) call (214) 465-7805. No COD's. Freight prepaid. Allow 3 weeks for personal checks to clear. Texas residents add 5%. Foreign orders add 30%. Prices subject to change without notice.

Circle 157 on inquiry card.

BYTE March 1981

245

BYTELINES

DEC, even though DEC closed two of its retail outlets and has put a halt to its retail expansion.

In a related development, Hewlett-Packard has entered into an agreement to sell its HP-1000L smallbusiness computer through ABC Computers Inc's 350 retail outlets.

I rogrammer Fined For Copying Software: A

Mobile County, Alabama, circuit court has fined a programmer $50,000 for copying his former employer's software and using it in a competing business he started. A jury decided that a theft had occurred, even though nothing material was taken. The prosecution maintained that the former employee could not have recreated the identical programs in such a short period of time. The defense said he had done so. The programmer plans to appeal.

I ersonal Computing On Corporate Machines:

Federal auditors discovered over 200 government employees at the Sandia Nuclear Weapons Research Center in Albuquerque, New Mexico, using the facility's Control Data Corporation systems for personal use. Sources report that 456 unauthorized files were located, including several hundred games such as Star Trek and Adventure, as well as poetry, jokes, personal letters, a beer-can collection catalog, and bowling-team rosters. One employee was caught helping local gamblers run a bookmaking operation.

Uoes Computer Crime Pay? It certainly does... according to Paul Nolan, supervisory special agent in the FBI's White Collar Crime Section. He estimates that non-computer-aided embezzlement averages $23,000 per occurrence, while computer-aided embezzle

ment averages $430,000. By the way, bank robbers average only $3000.

w olume Production For 64 K-BIt Memories:

Within two months, suppliers will start shipping the new 64 Kbit programmable memories to manufacturers and distributors. Prices will be in the $25 to $30 range; they'll drop under $20 in July. Fifteen suppliers have announced devices, although some of the specification sheets are tentative.

It's not yet clear when personal-computer manufacturers will start using the 64 K-bit chips in place of 16 K-bit circuits. Many will stick with the 16 K-bit device until the 64 K units show a significant price drop.

Intel has let it be known that its 64 K-bit memories will use redundant bits for increased yield, the same technique used by IBM and Western Electric in their inhouse circuits. Intel uses a "ROM-fuse" technique (an internal programmable readonly-memory) to decode addresses and replace one or more defective cells.

#Tda Status Report: It

is estimated that the DOD (Department of Defense) uses over 500 general-purpose computer languages and that $3 billion is spent each year for software development, whose control is a nightmare. That's what led the DOD to subsidize the Ada language project. The department wants Ada to be its only language.

In 1975, a DOD group undertook the task of evaluating twenty-three existing languages to find a standard language. None were found suitable. In mid-1978, the group invited specification recommendations from around the world and sponsored a competition among seventeen organizations. The Green language (later dubbed Ada),

developed by Cii Honeywell Bull (a French subsidiary of Honeywell), emerged the winner. Initial specifications were released in mid-1979 and refined and completed by mid-1980.

A fully functional Ada compiler for the entire language is expected to be available next year. Many private and educational institutions are currently developing Ada compilers, including Carnegie-Mellon University and the University of Karlsruhe, West Germany. Other schools studying various aspects of Ada include Stanford, Harvard, MIT, and the Universities of Texas, Massachusetts, Southern California, Pennsylvania, York (England), Tokyo, London, and the Technical University of Denmark.

The DOD has requested that the Ada compiler run on the DEC (Digital Equipment Corporation) VAX 11/780 and produce code for the VAX, the DEC PDP-11, and the military AN/GYK-12.

A number of institutions already have "Little Ada" compilers running, and it's likely that we'll see a "Tiny Ada" implementation for 8080/Z80 systems by year's end.

V/hlo Scientific Sold:

Ohio Scientific Inc (OSI), one of the early pioneers in personal-computing systems, has been purchased for an undisclosed sum by M/A-COM Inc of Burlington, Massachusetts. M/A-COM manufactures business communications equipment. OSI had sales of $14.8 million for the 10-month period ending October 1980. Mike Cheiky, OSI founder, will remain as vice-president of development. In all likelihood OSI will move away from personal computing and into the small-business market.

R

andom Rumors:

Apple is rumored to be frantically working on a 16-bit computer system using the

Motorola 68000.... Sony and Canon are about to introduce computers using the Motorola 6809 8-bit microprocessor.... Radio Shack may introduce a disk system for the TRS-80 Color Computer system.... According to insiders, Texas Instruments will soon have a low-cost system and a Viewdata-type terminal. Tl is concerned over Radio Shack's growing domination of the consumer communications market.... Experts predict that Radio Shack will have 40,000 people hooked up to data bases through their equipment by year end....

The Apple III appears to be designed to accept one of the new 5 Va -inch Winchester hard disks in place of its 514-inch floppy-disk drives.... Informed sources say that Zilog is at last shipping fully functional Z8000s. Reportedly, the first four versions had some op codes that did not execute correctly... Sony and Matsushita are expected to introduce portable microcomputer products that fit into your briefcase. They are intended for electronic mail and database access applications. (See "The Panasonic and Quasar Hand-Held Computers," by Gregg Williams and Rick Meyer January 1981 BYTE, page 34.) ...Expect a CP/M-like operating system for Atari's 800 personal computer.... Okidata will unveil a 35 cps overlapping dot-matrix printer for under $1000 at the National Computer Convention in May....

MAIL: I receive a large number of letters each month as a result of this column. If you write to me and wish a response, please include a self-addressed, stamped envelope

Sol Llbes POB 1192 Mountainside NJ 07081

246 March 1981 © BYTE Publications Inc

The Text Solution for APPLE II®

Now APPLE II® Owners Can Solve Text Problems

With VIDEOTERM 80 Column by 24 Line Video Display

Utilizing 7 X 9 Dot Character Matrix

Perhaps the most annoying shortcoming of the Apple II® is its limitation of displaying only 40 columns by 24 lines of text, all in uppercase. At last, Apple II® owners have a reliable, trouble-free answer to their text display problem. VIDEOTERM generates a full 80 columns by 24 lines of text, in upper and lowercase. Twice the number of characters as the standard Apple II® display. And by utilizing a 7 by 9 character matrix, lower case letters have true descenders. But this is only the start.

VIDEOTERM, MANUAL, SWITCHPLATE

VIDEOTERM

Pascal

Other Boards

'; - * in '()* + ,-. /

B123456789:;< = >? f ft B C D E F G HIJ K L H N 0 P 0 R 5 T U V W X Y Z [ \ ] A . 'abcdefjhijklmnD pqrstuvwxyzt i ) * I

7X12 MATRIX 18X80 OPTIONAL

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7X9 MATRIX 24X80 STANDARD

Advanced Hardware Design

Available Options

VIDEOTERM lists BASIC programs, both Integer and Applesoft, using the entire 80 columns. Without splitting keywords. Full editing capabilities are offered using the ESCape key sequences for cursor movement. With provision for stop/start text scrolling utilizing the standard Controls entry. And simultaneous on-screen display of text being printed.

Installation of VIDEOTERM in slot 3 provides Pascal immediate control of the display since Pascal recognizes the board as a standard video display terminal and treats it as such. No changes are needed to Pascal's MISC.INFO or GOTOXY fiies, although customization directions are provided. All cursor control characters are identical to standard Pascal defaults.

The new Microsoft Softcard' is supported. So is the popular D. C. Hayes Micromodem II" , utilizing customized PROM firmware available from VIDEX. The powerful EasyWriter" Professional Word Processing System and other word processors are now compatible with VIDEOTERM. Or use the Mountain Hardware ROMWriter' (or other PROM programmer) to generate your own custom character sets. Naturally, VIDEOTERM conforms to all Apple OEM guidelines, assurance that you will have no conflicts with current or future Apple II' expansion boards.

VIDEOTERM's onboard asynchronous crystal clock ensures flicker-free character display. Only the size of the Pascal Language card, VIDEOTERM utilizes CMOS and low power consumption ICs, ensuring cool, reliable operation. All ICs are fully socketed for easy maintenance. Add to that 2K of on-board RAM, 50 or 60 Hz operation, and provision of power and input connectors for a light pen. Problems are designed out, not in.

The entire display may be altered to inverse video, displaying black characters on a white field PROMs containing alternate character sets and graphic symbols are available from Videx. A switchplate option allows you to use the same video monitor for either the VIDEOTERM or the standard Apple IP display, instantly changing displays by flipping a single toggle switch. The switchplate assembly inserts into one of the rear cut-outs in the Apple IP case so that the toggle switch is readily accessible. And the Videx KEYBOARD ENHANCER can be installed, allowing upper and lower case character entry directly from your Apple IP keyboard.

1K of on-board ROM firmware controls all operation of the VIDEOTERM. No machine language patches are needed for normal VIDEOTERM use.

Characters 7x9 matrix Options 7 x 12 matrix option;

Alternate user definable character set option; Inverse video option.

Firmware Version 2.0 Display

24 x 80 (full descenders)

18 x 80(7 x 12 matrix with full descenders)

Want to know more? Contact your local Apple dealer today for a demonstration. VIDEOTERM is available through your local dealer or direct from Videx in Corvallis, Oregon. Or send for the VIDEOTERM Owners Reference Manual and deduct the amount if you decide to purchase. Upgrade your Apple II* to full terminal capabilities for half the cost of a terminal. VIDEOTERM. At last.

Apple II' is a trademark of Apple Computer Inc. ROMWriter' is a trademark at Mountain Hardware Inc Micromodem II" is a trademark of D. C. Hayes Associaies Soltcard' Is a trademark at Microsoft EasyWrilef is a trademark of Information Unlimited Soltw

> VIDEOTERM includes manual $345

• SWITCHPLATE S 19

■ MANUAL refund withpurchase. 5 19

• 7x12CHARACTERSET $ 39

• MICROMODEM FIRMWARE S 25

APPLE II® OWNERS!

introducing the

KEYBOARD & DISPLAY

ENHANCER

■ PUT THE SHIFT AND SHIFT LOCK BACK WHERE IT BELONGS »SEE REAL UPPER AND lower CASE ON THE SCREEN • ACCESS ALL YOUR KEYBOARD ASCII CHARACTERS

Videx has the perfect companion for your word processor software: the KEYBOARD AND DISPLAY ENHANCER Install the enhancer in your APPLE II and be typing in lower case just like a typewriter. If you want an upper case character, use the SHIFT key or the CTRL keyfor shift lock. Not only that, but you see upper and lower case on the screen as you type. Perfectly compatible with Apple Writer and other word processors like, for example. Super-Text.

If you want to program in BASIC, just put it back into the alpha lock mode; and you have the original keyboard back with a few im

provements. Now you can enter those elusive 9 characters directly from the keyboard, or require the Control key to be pressed with the RESET to prevent accidental resets

KEYBOARD AND DISPLAY

ENHANCER is recommended for use with all revisions of the APPLE II. It includes 6 ICs. and EPROM and dip-switches mounted on a PC board, and a jumper cable. Easy installation, meaning no soldering or cutting traces. Alternate default modes are dip-switch selectable. You can even remap the keyboard, selecting an alternate character set. for custom applications.

PRICE • KDE-700 (REV. 7 or greater) J129.

■ KDE-000 (REV. 6 or less) S129.

Apple 11* is a trademark of Apple Computer. Inc.

VIDEX 897 N.W. Grant Avenue Corvallis, Oregon 97330 Phone (503) 758-0521

Circle 158 on inquiry card.

BYTE March 1981 247

iTSSvEPi

WITH DSC'S 10% CLUB

• YOU CAN BUY HARDWARE, SOFTWARE, AND SUPPLIES AT 10% ABOVE WHOLESALE

• JOIN NOW: $15.00 ANNUAL MEMBERSHIP FEE INCLUDES $10.00 CREDIT TOWARD FIRST PURCHASE AND CATALOG OF PRODUCTS

• TERMS — PREPAYMENT, CASH, CERTIFIED CHECK, M.O., M.C. AND VISA ADD 4%, FOB PHI LA., PA.

• WARRANTIES — ALL EQUIPMENT CARRIES MANUFACTURER'S WARRANTY AND WILL BE SERVICED BY MANUFACTURER OR REPRESENTATIVE

COMPUTERS

Intertec - SuperBrain 32K

SuperBrain64K

SuperBrain QD 64K

Intertube III

Atari - 400 Computer

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815Dual Disk Drive

Applell + Apple II Plus-16K

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48K

Drives- Lobo for Apple-5%" with controller

VRData- 40tk1side

80tk 1side

40 tk 2 side

80tk2side 8" CDC 9404B, Mod II comp. 16K memory

Modems - D-Cat direct connect

Lexicon acoustic

Radio Shack - Mod. I Expansion Interface

Model III 16K

Model MI32Kw/2Drives

ColorComputer4K

ColorComputer 16K

PRINTERS

Centronics-730-1 parallel

730-3 serial

737-1 parallel

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C. Itoh Starwriter25cps parallel SUPPLIES

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D VISA

EXPIRATION DATE

Software Received

SDisk Supply Co. _ SUITE 439, 111S. OLIVE ST. MEDIA, PA 19063 (215)461-5437 ^^Bl

Apple II, PET, and TRS-80

B-l Nuclear Bomber,

historical strategy game for the Apple, PET, and TRS-80. Cassette, $14.95. Avalon Hill Game Company, 4517 Harford Rd, Baltimore MD 21214.

Planet Miners, strategy game for the Apple, PET, and TRS-80 (three versions sold together). Cassette, $14.95. Avalon Hill Game Company (see above).

TRS-80

Disk Editor/Assembler,

line editor and relocatable machine-language assembler for the TRS-80. Floppy disk, $99.95. Radio Shack, 1 Tandy Ctr, Fort Worth TX 76102.

FORTRAN, programming language and utilities for the TRS-80. Floppy disk, $99.95. Radio Shack (see above).

Lost Ship Adventure, Adventure program for the TRS-80. Cassette, $14.95. The Programmer's Guild, POB 66, Peterborough NH 03458.

Profile, general-purpose data base and report writer for the TRS-80. Floppy disk, $79.95. Radio Shack (see above).

Real Estate Volume II, mortgage analysis program for the TRS-80. Cassette, $29.95. Radio Shack (see above).

Scripsit, word-processing package for the TRS-80. Floppy disk, $99.95. Radio Shack (see above).

Standard & Poor's Stockpak and Portfolio Management System, stockanalysis program for the TRS-80. Floppy disk, $49.95. Radio Shack (see above).

Star Trek 4.0, action game for the TRS-80. Cassette, $14.95. The Programmer's Guild (see above).

Superdisk, collection of utility programs for the TRS-80. Floppy disk, $49.95. The Programmer's Guild (see above).

VisiCalc, numerical computation and forecasting tool for the TRS-80. Floppy disk $99.95. Radio Shack (see above).

Texas Instruments 99/4 Early Learning Fun,

educational activity for children for the TI 99/4. Floppy disk, $30. Texas Instruments, 13500 N Central Expy, Dallas TX 75231.

Personal Record Keeping, computer-based filing system for the TI 99/4. Program cartridge, $50. Texas Instruments (see above).

Speech Editor, speech synthesis aid for the TI 99/4. Program cartridge, $45. Texas Instruments (see above).

Other Computers

Nevada COBOL, version of the COBOL language for CP/M systems. Eight-inch floppy disk, $99.95. Ellis Computing, 1480 17th Ave, San Francisco CA 94122.

This is a list of software packages that have been received by BYTE Publications during the past month. The list is correct to the best of our knowledge, but it is not meant to be a full description of the product or the forms in which the product is available. In particular, some packages may be sold, for several machines or in both cassette and floppy-disk format; the product listed here is the version received by BYTE Publications.

This is an all-inclusive list that makes no comment on the quality or usefulness of the software listed. We regret that we cannot review every software package we receive. Instead, this list is meant to be a monthly acknowledgment of these packages and the companies that sent them. Companies sending software packages must include the suggested list price of the packages and (where appropriate) the alternate forms in which they are available.

248 March 1981 © BYTE Publications Inc

Computer experts (the pros) usually have big computer experience. That's why when they shop system software for ZBO micros, they look for the big system features they're used to. And that's why they like Multi-User OASIS. You will too.

DATA INTEGRITY: FILE & AUTOMATIC RECORD LOCKING

The biggest challenge for any multi-user system is co-ordinating requests from several users to change the same record at the same time.

Without proper co-ordination, the confusion and problems of inaccurate or even destroyed data can be staggering.

Our File and Automatic Record Locking features solve these problems.

For example: normally all userscan view a particular record at the same time. But, if that record is being updated by one user, automatic record locking will deny all other users access to the record until the up-date is completed. So records are always accurate, up-to-date and integrity is assured.

Prosdemandfile& automatic record locking. OASIS has it.

SYSTEM SECURITY: LOGON, PASSWORD & USER ACCOUNTING

Controlling who gets on your system and what they do once they're on it is the essence of system security.

(THEN COMPARE.)

Without this control, unauthorized users could access your programs and data and do whatthey like. A frightening prospect isn't it?

And multi-users can multiply the problem.

Butwiththe Logon, Password and Privilege

Level features of Multi-User

OASIS, a system manager can specify for each user which programs and files may be accessed — and for what purpose.

Security is further enhanced by User Accounting —a feature that lets you keep a history of which user has been logged on, when and for how long.

Pros insist on these security features. OASIS has them.

EFFICIENCY: RE-ENTRANT BASIC

A multi-user system is often not even practical on computers limited to 64K memory.

OASIS Re-entrant BASIC makes it practical.

How?

Because all users use a single run-time BASIC module, to execute their compiled programs, less

memory is needed. Even if you have more than 64K, your pay-off is cost saving and more efficient use of all the memory you have available—because it services more users.

Sound like a pro feature? Itis.AndOASIS hasit.

AND LOTS MORE.

Multi-User OASIS supports as many as 16 terminals andean run in as little as 56K memory. Or, with bank switching, as much as 784K.

Multi-Tasking lets each user run more than one jobatthe sametime.

And there's our BASICa compiler, interpreter and debugger all in one. An OASIS exclusive.

Still more: Editor; Hard & Floppy Disk Support: Keyed (ISAM), Direct & Sequential Files: Mail-Box;

Scheduler; Spooler; all from OASIS.

Our documentation is recognized as some of the best, most extensive, in the industry. And, of course, there's plenty of application software.

Put it all together and it's easy to see why the real pros like OASIS. Join them. Send your order today.

OASIS IS AVAILABLE FOR

SYSTEMS: Altos; Compucorp. Cromemco; Delta Producls: Digital Group; Digital Microsystems. Dynabyte Godbout: IBC; Index; Intersyslems; North Star. Onyx; SD Systems; TRS BO Mod II. Vector Graphic. Vorimex

CONTROLLERS: Bell Controls: Cameo Corvus; Konan; Micromation; Micropolis: Tarbell; Teletek; Thinkertoys; X Comp

Wnle (or complete.

Iree Application Software Directory

1 PLEASE SEND ME:

Price

with

Manual

■ Product

Manual

Only

I OPERATING SYSTEM

(Includes:

EXEC Language;

m File Management;

Usei Accounting;

■ Device Drivers;

| Print Soooler;

■ General Text

■ Editor, etc )

1 SINGLE-USER

S150

SI 7.50

| MULTI-USER

350

17 50

■ BASIC COMPILER/

■ INTERPRETER/DEBUGGER

too

1500

' RE-ENTRANT BASIC

■ COMPILER/INTERPRETER/

" DEBUGGER

150

15.00

- DEVELOPMENT PACKAGE

' (Macro Assembler;

_ Linkage Editor;

1 Debugger}

150

25.00

■ TEXT EDITOR S

| SCRIPT PROCESSOR

ISO

15.00

| DIAGNOSTIC &

CONVERSION UTILITIES

| (Memory Test;

Assembly Language;

1 Conveners: File

Recovery: Disk Test;

1 File Copy from

'' otner OS; etc )

100

15.00

m COMMUNICATIONS

■ PACKAGE

; (Terminal Emulalor;

■ File Send S Receive)

too

15.00

■ PACKAGE PRICE

p (All of Above)

SINGLE-U5ER

500

60.00

[1 MULTI-USER

850

6000

I FILE SORT

too

15.00

■ COBOL-ANSI '7«

750

35.00

Order OASIS from:

Phase One Systems, Inc.

7700 Edgewater Drive, Suite 830

Oakland, CA 94621

Telephone (415) 562-8085 TWX 910-366-7139

NAME

STREET (NO BOX =)

CITY

ZIP

STATE

AMOUNTS

{Attach system description;

add S3 for shipping;

California residents add sales tax)

□ Check enclosed D VISA

□ UPS C.O.D. □ Master-charge

Card Number

Expiration Date

Signature

MAKES MICROS RUN LIKE MINIS

Circle 160 on inquiry card.

BYTE March 1981

249

6809 SOFTWARE

uTwrq; i ini]

BY MICROWARE*1

OS-9™ MULTIPROGRAMMING OPERATING SYSTEM

Vm true multitasking, real time operating system for / M timesharing, software development, database, L m process control, and other general applications. This versatile OS runs on almost any 6809-based computer.

■ UNIX™ -like file system with hierarchical directories, byte-addressable random-access files, and full file security. Versatile, easy-to-use input/output system is hardware independent and expandable.

■ Powerful "shell" command interpreter features: I/O redirection, multiple job stream processing, and more. Includes a complete set of utility commands.

■ OS-9 Level Two uses hardware memory management and can address over one megabyte of memory. Also includes pipes and filters for inter-process data transfers.

■ OS-9 Level One runs on systems without memory management hardware having up to 56K memory.

□ OS-9 Level Two $495* □ Level One $195

BASIC09™ PROGRAMMING LANGUAGE SYSTEM

Extended BASIC language compiler/interpreter with integrated text editor and debug package. Runs standard BASIC programs or minimally-modified PASCAL programs.

■ Permits multiple named program modules having local variables and identifiers. Modules are reentrant, position independent and ROMable.

■ Additional control statements for structured programming: IF ... THEN ... ELSE, FOR ... NEXT, REPEAT ... UNTIL, WHILE ... DO, LOOP ... ENDLOOP, EXITIF ... ENDEXIT.

■ Allows user-defined data types and complex data structures. Five built-in data types: byte, integer,

9 digit floating-point, string and boolean.

■ Runs under OS-9'" Level One or Level Two. D$195*

OTHER OS-9™ FAMILY SOFTWARE

■ Stylograph™ Screen-Oriented Word Processor

■ Interactive Assembler ■ Macro Text Editor

■ Interactive Debugger

BASIC09 and OS-9 are trademarks of Microware® and Motorola. UNIX is a trademark of Bell Laboratories.* Most software is available on ROM or diskette in versions for many popular 6809 computers. Contact Microware® for specific availability.

MICROWARG®

Microware Systems Corp., Dept. B2

5835 Grand Avenue, Des Moines, Iowa 50304

(515) 279-8844 • TWX 910-520-2535

Could you pass

this Red Cross

swimming test?

SWIM:

1. Breaststroke -100 Yds.

2. Sidestroke-lOOYds.

3. Crawl stroke-100 Yds.

4. Back crawl —50 Yds.

5. On back (legs only)-50 Yds.

6. Turns (on front, back, side).

7. Surface dive — underwater swim — 20 Ft.

8. Disrobe — float with clothes — 5 mins.

9. Long shallow dive.

10. Running front dive.

11. 10-minute swim.

Anybody who's taken a Red Cross swim course knows how tough it can be. There's a good reason.

We believe drowning is a serious business.

Last year alone, we taught 2,589,203 Americans not to drown—in the seven different swim courses we offer all across the country. (Incidentally, most of the teaching — as with almost everything American Red Cross does — is done by dedicated volunteers.)

A good many of the youngsters not only are learning to keep themselves safe. Thousands upon thousands of them are learning to become lif esavers.

And the life they save — may be your own.

Red Cross counting on you.

A Public Service of This Magazine & The Advertising Council &*«

250

March 1981 © BYTE Publications Inc

Circle 161 on inquiry card.

32K Board Pictured Above

Why Not the Best?

From The Dynamic RAM Company.

2MHz

4MHz

16K—$249

$259

32K—$375

$395

48K—$500

$530

64K—$625

$665

We have now been shipping our 2MHz dynamic RAM boards for over two years. Hundreds of 4MHz boards have been going out every month since early 1979. Our reliability is proven in the thousands of systems which contain our board. Many qualityminded systems houses across the country and overseas are using our boards for their equipment.

Our prices still beat all. Despite rising 16K memory chip prices (at least from reputable suppliers), Central Data continues to give you the best buy in memory today. Nobody offers a board with a capacity of 64K, assembled, tested, and guaranteed for a full year at the price we do.

Circle 162 on inquiry card.

Deselect around PROMs. Our

boards have the important deselect feature which lets you overlap any fixed memory in your system with no interference.

Our features make the board easily used and expanded. You address our boards on 16K boundaries with mini-jumps (small shorting plugs that slide over wirewrap pins) near the top of the board for easy access. If you want to expand your board after you have purchased it, all that you need to do is add memory. We can supply you with expansion packages ($150-2MHz, $1 60-4MHz) which include eight RAMs that you can depend on as well as two mini-jumps for addressing. And of course, our board never generates wait states.

Low power consumption keeps your computer running cool and reliable. The total power consumption of our 16K board is typically less than 4 watts (+8V @ 300ma, +1 6V @ 1 50ma and

-16V @ 20ma). Boards with additional memory typically increase power consumption only 1 watt per 16K!

Standard S-100 Interface. Our board is designed to interface with any standard S-1 00 CPU. All of the timing of the board is independent of the processor chip, and the board is set up for different processors by changing two plugs on the board.

Call or write us today. That will guarantee a fast response with more information on the board. Or make an order — you'll probably have the board in two weeks! If you're interested, also ask for a catalog on our Z8000 16-bit processor board designed for the MULTIBUS. All of these products are available to your local dealer, also.

Central Data Corporation, 713 Edgebrook Drive, PO Box 2530, Station A, Champaign, IL 61820. (217) 359-8010

Central Data

BYTE March 1981

251

Circle 163 on inquiry card.

TERMINALS FROM TRANSNET

DEC

PURCHASE PLAN -12-24 MONTH FULL OWNERSHIP PLAN • 36 MONTH LEASE PLAN

PURCHASE PER MOUTH

DESCRIPTION PRICE 1ZMOS. 24MOS J6MOS,

LA36DECwrllerll $1,695 S16Z S 90 S 61

LA34 OECwrlter IV 1,095 105 58 40

LA34 DECwrller IV Forms Ctrl. .. 1,295 124 68 46

LA120DECwrilerlllKSR 2,295 220 122 83

LA120 DECwrilerllIRO 2,295 220 122 83

VT100CRTDECscope 1,695 162 90 61

VT132 CRT DECscope 2,295 220 122 83

TI745 PortableTerminal 1,595 153 85 58

TI765 Bubble Memory Terminal . 2,595 249 138 93

TI783 Portable KSR, 120 CPS ... 1,745 167 93 63

TI785 Portable KSR, 120 CPS ... 2,395 230 12B 86

TI787 Portable KSR, 120 CPS ... 2,845 273 152 102

TI810RO Printer 1,895 182 102 69

TI820 KSR Printer 2,195 211 117 80

730 DeskTop Printer 715 69 39 26

737 W/P Desk Top Printer 895 86 48 32

704 RS232-C Printer 1,795 172 96 65

6081 High Speed Band Printer .. 5.495 527 293 198

DTB0/1 CRT Terminal 1,695 162 90 61

DT80/1L15"ScreenCRT 2,295 220 122 83

DT60/5APLCRT 2,095 200 112 75

DT80/5L APL15" CRT 2,595 249 138 94

ADM3A CRT Terminal 875 84 47 32

ADM31CRTTerminal 1,450 139 78 53

ADM42 CRT Terminal 2,195 211 117 79

1420 CRT Terminal 945 91 51 34

1500 CRT Terminal 1,095 105 58 40

1552 CRT Terminal 1,295 125 70 48

.,., , .,: _ Letter Quality KSR, 55 CPS 3,395 326 181 123

>" ■ Letter Quality RO, 55 CPS 2,895 278 154 104

2621A CRT Terminal 1,495 144 80 54

2621P CRT Terminal 2,650 255 142 96

FULL OWNERSHIP AFTER 12 OR 24 MONTHS • 10% PURCHASE OPTION AFTER 36 MONTHS ACCESSORIES AND PERIPHERAL EQUIPMENT

ACOUSTIC COUPLERS • MODEMS • THERMAL PAPER • RIBBONS • INTERFACE MODULES • FLOPPV DISK UNITS

OTHER POPULAR TERMINALS, COMPUTER PERIPHERALS AND COMPUTERS AVAILABLE.

TEXAS INSTRUMENTS

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RA NSlYETcorporation

1945 ROUTE 22 ■ UNION, N.J. 07083 • (201) 688-7800

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Books Received

Basic Computer Programs for Business, Volume I, Charles D Sternberg. Rochelle Park NJ: Hayden Book Company Inc, 1980; 25 by 20 cm, 264 pages; softcover, ISBN 0-8104-5162-X, $9.95.

Basic FORTRAN, James S Coan. Rochelle Park NJ: Hayden Book Company Inc, 1980; 15.5 by 23 cm, 248 pages, softcover, ISBN 0-8104-5168-9, $8.95.

Communicating with Microcomputers, Ian H Witten. London, England: Academic Press Inc Ltd, 1980; 15.5 by 23 cm, 164 pages, hardcover, ISBN 0-12-760750-1, $18; softcover, ISBN 0-12-760752-8, $10.50.

Computers and Programming Guide for Scientists and Engineers, second edition, Donald D Spencer. Indianapolis IN: Howard W Sams & Company Inc, 1980; 14 by 22 cm, 463 pages, softcover, ISBN 0-672-21693-0, $15.95.

The Computer in the School: Tutor, Tool, Tutee, Robert Taylor, editor. New York: Teachers College Press, 1980; 15.5 by 23.5 cm, 274 pages, softcover, ISBN 0-8077-2611-7, $14.95.

Computer/Law Journal, Volume II, Number 2, Jay Becker, editor. Los Angeles CA: Center for Computer/Law, 1980; 17.5 by 25.5 cm, 469 pages, softcover, ISSN 0164-8756, $16.

Designs of VMOS Circuits with Experiments, Robert T Stone and Howard M Berlin. Indianapolis IN: Howard W Sams & Company Inc, 1980; 14 by 22 cm, 174 pages, softcover, ISBN 0-672-21686-8, $10.95.

A Guide to FCC Equipment Authorizations, Willmar K Roberts. New Smyrna Beach FL: Willmar

This is a list of books received at BYTE Publications during this past month. Although the list is not meant to be exhaustive, its purpose is to acquaint BYTE readers with recently published titles in computer science and related fields. We regret that we cannot review or comment on all the books we receive; instead, this list is meant to be a monthly acknowledgment of these books and the publishers who sent them.

K Roberts, 4637 Van Kleeck Dr, 1980; 21.5 by 27.5 cm, 142 pages, softcover, ISBN none, $24.50 in North America, $29.50 elsewhere.

Introduction to Pascal, Including UCSD Pascal, Rodney Zaks. Berkeley CA: Sybex, 1980; 18 by 23 cm, 421 pages, softcover, ISBN 0-89588-050-4, $12.95.

Introduction to TRS-80 Level II BASIC and Computer Programming, Michael P Zabinski, PhD. Englewood Cliffs NJ: PrenticeHall Inc, 1980; 22.5 by 29 cm, 186 pages, hardcover ISBN 0-13-499970-3, $14.95; softcover, ISBN 0-13-499962-2, $10.95.

Micromatics, Steven K Roberts. Elmwood CT: Scelbi Publications, 1980; 22 by 29 cm, 190 pages, hardcover, ISBN none, $19.95.

Modern Microprocessor System Design, Daniel R McGlynn. Somerset NJ: John Wiley & Sons, 1980; 22.5 by 29 cm, 295 pages, hardcover, ISBN 0471-06492-0, $21.95.

The Nature of Computation: An Introduction to Computer Science, Ira Pohl and Alan Shaw. Rockville MD: Computer Science Press Inc, 1981; 16 by 23.5 cm, 397 pages, hardcover, ISBN 0-914894-12-9, $16.95.

Owning Your Home Computer, Robert L Perry. New York: Everest House, 1980; 19 by 25.5 cm, 224 pages, softcover, ISBN 0-89696-093-5, $10.95.

Personal Computers Handbook, Walter H Buchsbaum, Sc D. Indianapolis IN: Howard W Sams & Company Inc, 1980; 14 by 22 cm, 286 pages, softcover, ISBN 0-672-21724-4, $11.95. ■

252 March 1981 © BYTH Publications Inc

Circle 164 on inquiry card.

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Circle 165 on inquiry card.

BYTE March 19B1 253

Circle 166 on inquiry card.

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The P&T-488 permits an S-100 computer to operate as a talker, listener, or controller on the IEEE-488 instrumentation bus for less than half the cost of calculator-based systems. Software packages which give access to the 488 bus from high level languages such as BASIC are available for CP/M, North Star DOS /BASIC, and Cromemco CDOS. Or "roll your own" system with the custom system package of assembly language drivers. P&T-488, assembled and tested, + any software package: $450 (domestic USA)

TSoof

Ask BYTE

Conducted by Steve Ciarcia

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Modem Modification

Dear Steve,

I read "A Build-It-Yourself Modem for Under $50" (August 1980 BYTE, page 22) with great interest, as I do so many of your articles. Can the circuitry be modified easily to provide either originate or answer operation at the flick of a switch? From your article, it seems that the only difference between the originate and answer modes is the value of two capacitors in both the modulator and demodulator. If the values of these capacitors are switch-selected, then the modem could be either an originate- or an answer-only unit, as desired.

I have an uneasy feeling about several aspects of this scheme. Since you say that the capacitances are critical, will the switch capacitances cause trouble? Secondly, will the variable potentiometer settings be unique to each mode of operation, thus necessitating separate potentiometers for each switch setting?

It seems much more appealing to get expanded capability by buying a few additional components than by buying another complete set of components for both the modulator and demodulator. Jonathan K Davis

An originate/'answer modem is more complicated

to build than it might seem at first. While, in theory at least, the answer functions can be added to the design by changing a few capacitors and resistors, the logistics of doing this presents a problem. The wires necessary to add these components and connect them through switches act like an antenna. Due to the high impedances in the circuit, it would probably become "swamped" with noise and cease reliable operation.

The only effective way to connect these components is through CMOS (complementary metal-oxide semiconductor) switches such as the 4052 dual l-of-4 analog multiplexer, which are mounted close to the modem board. Separate potentiometer settings for answer and originate modes are necessary as well. If done as a printed circuit, the result is a more complicated and expensive board.

I won't tell you that simply installing components with a switch will not work, but I hesitate to suggest it. Success depends on your construction abilities.

As for the kit mentioned in the article, many experimenters seem to be purchasing two kits at once (they are still available). Apparently they intend to change a few components on the second board to make it "answer."

Also, instead of two speakers and two rubber

In "Ask BYTE," Steve Ciarcia answers questions on any area of microcomputing. The most representative questions received each month will be answered and published. Do you have a nagging problem? Send your inquiry to:

Ask BYTE

c/o Steve Ciarcia

POB 582

Glastonbury CT 06033 If you are a subscriber to The Source, send your questions by electronic mail or chat with Steve (TCE3I7) directly. Due to the high volume of inquiries, personal replies will be given as time permits. Please enclose a self-addressed, stamped envelope, and be sure to include "Ask BYTE" in the address.

254 March 1981 © BYTE Publications Inc

Circle 167 on inquiry card.

CHRISLIN YEARS AHEAD IN MEMORY DESIGN

WE'VE DONE IT AGAIN — State of the Art Multibus® Memory Design. First to offer up to 512K on one board, and CHRISLIN again brings pricing sanity to the memory market. Why pay over $2000 for our competitor's 64K x 8 memory board when we will give you the CI 8086 128K x 9 memory for just $1500 or better yet, the CI-8086 512K x 9 memory module for $4700.

Up to 512K bytes in a single option slot. Available in 64K. 96K, 128K, 256K, or 512K configurations. On board parity generator checker, for both 8 bit or 16 bit systems. Off shelf deliveries.

CI-6800-2 — 16KB to 64KB. Plugs directly into Motorola's EXORciser I or II. Hidden refresh up to 1.5 Mhz. Cycle stealing at 2 Mhz. Addressable in 4K increments with respect to VXA or VUA. On board parity. 64K x 9 $750.00.

IftYt'll •

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CI-S100 — 16KB to 64KB. Transparent hidden refresh. No wait states at 4 Mhz. Compatible with Alpha Micro and all Major 8080, 8085 and Z80 Based S100 Systems. Expandable to 512K bytes thru Bank Selections. 64K x 8 $750.00.

CI-8080 — 16KB to 64KB on a single board. Plugs directly into MDS 800 and SBC 80/10. Addressable in 4K increments up to 64K. 16KB $390.00. 64KB $750.00.

CM 103 — 16KB to 256KB on a single dual height board. Plugs directly into LSI 11/2. H11 or LSI 11 /23. Addressable in 2K word increments up to 256KB. 8Kx 16 $390.00.32Kx 16 $750.00.128K x 18 $2880.00.

CI-6800 — 16KB to 64KB on a single board. On board hidden refresh. Plugs directly into EXORciser I and compatible with Rockwell's System 65. Addressible in 4K increments up to 64K. 16K x 8 $390.00. 64K x 8 $750.00.

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Multibus is a trademark of the Intel Corp. LSI II is a trademark of Digital Equipment Corp. EXORciser is a trademark ot Motorola

Circle 168 on inquiry card. BYTE March 1981 255

Circle 169 on inquiry card.

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Ask BYTE

cushions in the coupler kit, MicroMint is shipping (at no extra cost) a ceramic microphone in place of one speaker. Even though 1 designed the prototype using an 8-ohm speaker as the "mike, " the ceramic unit is far more reliable....Steve

Communications

Dear Steve,

I am working on converting your biphase encoding/decoding circuits to use 8- instead of 4-bit words. (See "Hand-Held Remote Control for Your Computerized Home," July 1980 BYTE, page 22.) This approach looks promising, but I am not sure which communications medium I should use the circuits for. Radio is a possibility, but I really don't like the idea of having its interference. Infrared also looks good, but I am not sure about achieving long-range communications with it. To the best of my knowledge, the same holds true for ultrasonics. Can you suggest a particular system?

Also, in figure 3 of your article, there is a note next to the FSK OUTPUT saying that it can be connected to figure 5's input; however, figure 5 has two inputs labeled audio input modulation, plus and minus. Why? Arthur Allen Gleckler

Any of the systems you list will work. For the most part, ultrasonics and infrared communication are limited to use in one room. If the experience of modelairplane builders is worth anything, 49 MHz radio control may be your best bet. Interference presents less of a problem if you use the "smarts" available with a microprocessor. Perhaps you should require that, for any command to be acted upon, it must be received correctly with a synchronization word before and after the command.

There are many coding schemes that insure you

don't lose data. Rather than sending a single bit, you could send the same bit eight successive times. This makes for slow but reliable reception. Heathkit sells a variety of radio-control equipment that is adaptable to the task.

Finally, in figure 5, the plus (+) lead would be connected to the biphase output of figure 3 and the minus ( — ) lead would be connected to ground....Steve

BSR X-10

Dear Steve,

I read with interest your article "Computerize a Home." (See the January 1980 BYTE, page 28.)

Can you suggest references or other aids for pursuing the option of directly synthesizing the commandconsole waveform and transmitting it directly onto the AC line? This approach may be useful in an application for which I'm developing a product. Jim Konsevich

It so happens that the cover article of the September 1980 issue of Radio Electronics is about the BSR X-10. The article fully describes how to synthesize waveforms for direct injection into the AC line. It also has schematics of the command console and typical receivers. It should be just what you need.

By the way, I wrote the article.... Steve

Reference Needed

Dear Steve,

In your article "Computer-Controlled Security for Your Home" (January 1979 BYTE, page 56) you indicate an MM5369 in figure 4. I cannot find any reference or crossreference for this device. It looks like an interesting unit; where can I get one and who manufactures it? James Bush

256

March 1981 © BYTE Publications lnc

Circle 170 on inquiry card.

SERIAL INTERFACE

(TO/FROM HOST)

RS232C

J2

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THE ZOBEX CPU IS A IEEE STANDARD S-100 MODULE THAT INCORPORATES PROCESSOR, 4 SERIAL AND 3 PARALLEL I/O, REAL-TIME CLOCK, AND PROM FEATURES, ALL ON ONE BOARD. IT IS ADAPTABLE TO WIDE VARIETY OF HOME AND OEM APPLICATIONS. THIS BOARD WILL RUN MODERN INTERRUPT DRIVEN OPERATING SYSTEMS SUCH AS **MP/M, WITH NO EXTERNAL CIRCUITRY.

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*Cromemco, Cromix are trade marks of Cromemco Inc **MP/M is trade mark of Digital Research

BYTE March 1981

257

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— Users share common disk storage and master printer. The master processor handles disk (floppy and hard) access and printing, as well as automatic master printer spooling.

— Each user has a system reset button. If any of the users, whether local or remote (thru MODEM), should "crash", he may reset his CPU by depressing the console break key. Other users will not be affected providing complete autonomy. —Additional features include expandability to 100+ user terminals, interfaces to any ASCII CRT terminal, messages can be passed among users, and multi-level file security and file sharing interlock are provided.

CP/M and MP/M are registered trademarks of Digital Research.

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Ask BYTE

Radio Shack sells the MM5369 as part number 276-1769, for 52.89. Radio Shack calls it an oscillator/ divider. Be aware that the + 12 V and ground-pin connections were listed incorrectly in the powerconnection table. Pin 8 is the ground and pin 2 is + 12 V....Steve

Character Descension

Dear Steve,

I own a Radio Shack TRS-80 Level II with 16 K bytes of memory, and I have installed an uppercase/ lowercase kit.

If you have seen a system with this kit, you probably noticed that the lowercase letters p, q, and y do not descend below the line. Actually, they are the same size as the uppercase letters. This can be irritating. To cure this, the character generator must be changed, but I have yet to find a compatible device to replace the old one. It must have the same characters (graphics, etc) and of course, the new p, q, and y. Please tell me where I can get such a device and its approximate cost? Mark T Cruse

Apparently the device that you want is made by Motorola, but is proprietary to Radio Shack. The standard MCM6670 installed in TRSSOs is only available in quantities of 5000 or greater. There is the preprogrammed MCM6674 that is available, but it is a 5 by 7 matrix. Try ordering a new character generator directly from Radio Shack. I do not see any 5 by 9 dot-matrix 18-pin horizontal-scan character generators in the Motorola data manuals that would be applicable.

I asked a few non-Radio Shack TRS-80 dealers about this, and some expect to eventually carry it. All the new TRSSOs have a revised character generator installed, even though the descenders

cannot be used without the uppercase/lowercase option Steve

Home Control

Dear Steve,

I work in software development for a videotext/ electronic publishing concern. Hardware is not my area of expertise; however, I have done some minimal automation of my home, including a humidity-controlled bathroom fan. I anticipate using a computercontrolled BSR X-10, but mine will be different from yours. (See "Computerize a Home," January 1980 BYTE, page 28.) I plan to have my ultrasonic controller run through the computer to the X-10 unit. I hope to talk to the X-10 unit through an optoisolator that would replace the microphone in the unit.

The same technique can be applied to any remotely controllable consumer device. It avoids the potential conflicts between the various ultrasonic and infrared control methods used in televisions, turntables, cassette decks, and other products. In the future, a videodisk, a Telidon videotex terminal, and an electronic-music library will join the list of controlled devices. There will be an ultrasonic receiver in each room. To complement the computer control, each device will retain its local controls.

I am working on a computer-controllable preamplifier for my stereo, incorporating reed-switch relays and a voltagecontrolled amplifier. Crown has a unit on the market, but it's a little too expensive. The preamplifier will lower its output by 20 dB whenever the telephone or the door is answered, etc.

I hope to stay with a single-board computer for the simple scheduling and control functions, but I have not yet calculated my memory requirements. I'm considering an SD Systems Z80 starter kit with an addi

258

March 1981 © BYTE Publications Inc

Circle 171 on inquiry card.

Why The People Who Know Use

FMS-80

FMS-80, a data base management system, is the most powerful DBM program available to the microcomputer industry. Written in assembly language, it offers these features:

• Operates on CP/Mf MP/M" or CDOS" systems.

• User Definable: Screen formatting with up to 255 screens per data file, report generator, and menus capable of calling other CP/M programs or FMS-80 programs.

• No restrictions to record size other than available RAM memory size.

• Instantaneous data record inquiry on indexed data records.

• Ca])able of selecting on any field or multiple fields with multiple selection criteria (fields do not have to be keyed).

• Mathematical manipulation of numeric data fields (add, subtract, multiply and divide).

• Capable of collecting information from multiple data files and generating a new data file or report.

• All menu driven.

• Callable of abstracting data from other programs written in other languages.

• Available now (off the shelf).

All these capabilities are available with the added plus of ease of programming.

See What Users of FMS-80 Have to Say:

Mike Ketcham, systems consult ant and programmer for Management Information Systems: "FMS-80

allows me the flexibility of quickly creating programs for user applications. It is flexible, in that data can be entered in a form that the secretary recognizes and generates reports that the manager requires. Also, the userdefinable menus allow me to actually generate a menu from which the user can select, creating a true turnkey system!'Tom Niccoli, Partner, Computerland of Phoenix: FMS-80 is flexible enough to acquire data from an application program that was previously written ind allowed me to generate the reports that my customer needed. It closed the deal for me. Considering its capability, FMS-80 is one of the most cost-effective application programs available today."

If you're continuously asked to do applications programming, and you don't have the time to do it in Basic, consider FMS-80. For additional information on FMS-80, contact Systems Plus, 3975 East Bayshore, Palo Alto, CA 94303. Phone (415) 969-7047.

<5s5£>t Systems Plus

/

Mike Kotdiam. Management Information SysU.'tns, BulmonI, CA

"TM nl Digital Research, Pacific Crave, CA "TM of Cromemco, Sunnyvale, CA

Circle 172 on inquiry card.

BYTE March 1981

259

Circle 173 on inquiry card.

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Ask BYTE,

tional memory and I/O (input/output) board. Am I too optimistic?

I plan to loosely couple the control computer to a more general-purpose computer, for advanced scheduling and control functions (perhaps including voice recognition). The generalpurpose machine will be used as a programming terminal for work I do at home; I currently use a TI Silent 700. Whatever I get, it must have good graphics, because I want to use it as a Telidon terminal until the real thing gets to market. Incidentally, why are highspeed modems so expensive?

Putting intelligence into home applicances can make them more useful, as you so aptly demonstrate in your column. Putting that same intelligence behind a handheld controller would offer still more advantages. I've had a lot of fun considering the human engineering aspects of a single hand-held controller wielding so much power. Ian Smith

1 appreciate your activities. I have been attempting a similar effort during

the past year and a half. The BUSY BOX was specifically designed because ! was getting tired of expensive hard-wired AC control. I started out with a singleboard computer, but it has evolved into a 26 K-byte mainframe with sixteen I/O ports and many of the interfaces presented in my articles during the past year. It's quite possible to use a single-board computer, but you may find, as I did, that a larger unit accommodating a combination of assemblylanguage and BASIC programming is necessary. BASIC makes report generation much easier.

I too have been thinking of hand-held master controllers. I have a few designs and will probably have more articles on this subject in the near future. If you get something working in the meantime, let me know.

High-speed modems must pack a lot of information into a limited bandwidth and recover this information, often in noisy environments. The high cost is a function of the increased circuit complexity necessary to accomplish this feat. I wish you luck in your venture. ... Steve ■

And then

there were

none.

The list of already extinct animals grows . . . the great auk, theTexasgray wolf, the Badlands bighorn, the sea mink, the passenger pigeon .. .

What happens if civilization continues to slowly choke out wildlife species by species?

Man cannot live on a planet unfit for animals.

Join an organization that's doing something about preserving our endangered species. Get involved. Write the National Wildlife Federation, Department 105, 1412 16th Street, NW. Washington, ggj^ DC 20036. " It's not too late.

260 March 1981 © BYTE Publications Inc

Circle 174 on inquiry card.

Circle 175 on inquiry card.

" MICROPOLIS- Ml

THIS COULD BE THE START OF SOMETHING SMALL.

At Micropolis, we make a big deal over our small deals, too.

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When you ask us for help, we don't just slap a brochure in your hand, give you a plant tour, and show you out the back door. We actually work with you to get your system to market.

The single fact is, nobody can help systems integrators with

a broader range of high capacity, high performance, high reliability 51/4" floppy and 8" rigid disk products than we can. We offer storage modules, enclosures, power supplies, S-100 & SBC-80 controllers, cables and connectors, interfaces, single & multiuser 8080/Z-80 operating systems & disk BASIC software, documentation and tech training. And we offer as much or as little as you need, from complete sub-systems at the start to OEM drive and controller manufacturing licenses as you grow.

When you deal with Micropolis, you avoid a lot of the expense,

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A Simple Approach to Data Smoothing

Fred Ruckdeschel and Janice A Krinsky

c/o BYTE

POB 372

Hancock NH 03449

Existing trends in data may not be

visible because they are masked by

statistical fluctuations.

The storage and processing of data has become a major activity in modern society. Computers have created an increasing demand for data because of their highly organized storage and retrieval facilities. Computers have also provided a means for rapidly transforming data into a format that emphasizes particular aspects of the underlying information. Data and information as used in this context are not synonymous terms. The word data refers to sets of numbers. Information is the knowledge that may be derived from those numbers.

Data appears in many forms. For example, a person interested in stocks may have a history of daily quotations for a particular company. A businessman may have a weekly sales record for each item in his inventory. A hospital administrator may have a record of emergency admittances. A scientist may have a table of results from a series of experimental measurements. All these types of data, when plotted against time (or another independent variable), may contain information regarding trends. However, existing trends in the data may not be visible because they are masked by statistical fluctuations,

1978

Month

Sales Volume

January

3279

February

2421

March

4864

April

3629

May

3180

June

4744

July

6181

August

3653

September

3418

October

1722

November

1235

December

2408

Table 1: 1978 sales data

for a

hypothetical

company. The

figures indicate that the

produ

ct being

sold has

an obvious

seasonal appeal.

which are often a component of any real-world measurement.

The importance of somehow removing the "noise" (or statistical fluctuation) from the data may be seen by using a simple example. Consider the monthly sales-volume data for a new business or product as shown in table 1. The data clearly indicates that the sales generally peak in the summer, with a slump in late autumn. Plotting the data, as shown in figure 1, demonstrates the basic seasonal nature of the sales volume. If this data were to be used to supply information regarding the number of units that should be ready for sale for July of the next year, several factors would have to be taken into account, the first of which is the "noise" in the data.

As the sales are assumed to have started in January 1978, there is no previous history that can be used to directly measure the noise by a monthly comparison. Thus the noise must be extracted using the data given. If there is no reason to expect sales to be statistically much different during the next year, we can use the smoothed results for 1978 to predict 1979. If the raw data value of 6181 units were prepared for July 1979, there is a chance for that number to be too high, with a corresponding penalty to be paid (eg: bank interest) for maintaining the inventory. Thus, a more realistic estimate is required.

Predicting Future Performance

One approach to obtaining sales estimates is to assume a functional form for the average sales-volume behavior and perform a regression. One mathematical form which might be tried is:

S(t) = A + B X sin{ 2ir(t + t0)/12 }

(1)

where f=l represents January, f = 2 represents February, and so on. A regression using S(t) could be performed that minimizes the sum of the squares of the differences between the true values and the ones eventually calculated using S(t). The regressed coefficients would then be A, B, and f0/ and the desired estimate for July 1979 is then S(7).

There are two practical considerations that make this approach less than ideal for the average businessman. First, though the form of S(t) given above may be appropriate, it is simply a guess. Second, few businessmen have the knowledge, facilities, or inclination for doing

262 March 1981 © BYTE Publications Inc

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Listing 1: Listing of program for data smoothing. This program was written in North Star BASIC, version 6, release 4. To make the software portable to other machines, only a subset of the language was used. In most cases, only the statement delimiters, backslashes, need to be changed to colons, and certain commas changed to semicolons (in print statements) to get this program to operate in other BASICs (in particular, Microsoft BASIC).

1 REM

2 REM

3 REM DATA SMOOTHING PROGRAM

4 REM

5 REM BY F.R. RUCKDESCHEL

6 REM

7 REM

B REM

9 REM

10 DIM B<5»3),C(B,91>,D<70)»E(B)

11 REM DIMENSION OF D,Y AND Yl MAY HAVE

TO

12 REM INCREASED FOR LARGE SETS.

13 DIM U(8).U<8>12)iU(12) iY<70) iYK70)

14 PRINT

15 PRINT

16 PRINT 'DATA SMOOTHER FOR EQUALLY1

17 PRINT "SPACED DATA SETS1

IB PRINT

19 PRINT

20 PRINT "INPUT THE NUMBER OF"

21 PRINT "DATA POINTS IN SET: ",

22 INPUT N4

23 PRINT

24 PRINT "HOU MANY POINTS ARE"

25 PRINT "TO BE AVERAGED OVER! ",

26 INPUT N3

27 PRINT

28 PRINT "WHAT IS THE DESIRED LEVEL"

29 PRINT "OF FIT (1,2,3,4,5)! ",

30 INPUT Nl

31 PRINT

32 PRINT "WHAT IS THE DESIRED"

33 PRINT "DERIVATIVE (0,1,2,3)! ",

34 INPUT N2

35 REM CHECK FOR ERRORS

36 REM DETERMINE TABLE

37 GOSUB 169

38 REM CHECK ERROR CODES

39 GOSUB 193

40 PRINT

41 PRINT

42 IF E=0 THEN GOTO 50

43 PRINT "*** ERROR IN INPUT ***"

44 PRINT " ERROR CODE",E

45 PRINT

46 PRINT "RESTART"

47 PRINT

48 GOTO 20

49 REM IF THIS POINT PASSED, OK

50 PRINT

51 PRINT "INPUT DATA AS PROMPTED!"

52 PRINT

53 FOR K = l TO N4

54 PRINT K>TAB(6)>

55 INPUT Y(K)

5 6 NEXT K

57 REM PLOT ABS VALUE OF DATA

58 PRINT

59 PRINT

60 FOR K=l TO N4

61 D(K)=ABS(YCK ) )

62 NEXT K

A3 REM GO TO PLOTTING SUBROUTINE

64 GOSUB 472

65 REM GOTO SUPERVISOR SUBROUTINE

67 PRINT

68 GOSUB 118

69 REM RESULTS READY FOR DISPLAY

70 PRINT

71 PRINT

72 PRINT "THE SMOOTHED DATA IS! "

73 PRINT

74 FOR K = l TO N4

75 PRINT K,TAB(6>,Y1(K)

such a regression. Thus, a more reasonable method might be to simply "eyeball" a curve through the data (as done by the dashed lines in figure 1). Using the dashed curve, the businessman would plan on having about 4800 units ready in July, instead of 6181.

The eyeballing method shown above has two clear deficiencies. The first obvious shortcoming is the assumption that the data of the next year, 1979, is a continuation of the data of the present year, 1978. This assumption is violated because the slopes of the curve at the January and December end points are not the same. However, this could be corrected graphically by a second freehand curve that would make sure that the tangent lines at January and December are parallel.

The second and more important deficiency is that there is uncertainty whether the smoothed value obtained for July 1979 is statistically correct, coupled with a lack of knowledge as to what the expected error might be. For example, a "better" analysis might show that the estimate is 4900 units with a standard deviation of 700 units. Thus, if 4900 units were on hand, there would be a 50% chance that all the orders could be filled. If 5600 (4900 plus one standard deviation) were available, the probability would become roughly 83%. With this type of information (that is, conclusions about data), the businessman can better plan his inventory.

In the following sections, a very simple technique is presented for data smoothing. This technique is based on the use of tables that are applied to adjust the value of a given data point according to the weighted sum of the values of surrounding data points. The smoothing criterion used is that of least squares, although it is applied in a manner not commonly taught in numerical analysis courses. As we will see, the method is amenable to pencil and paper calculations, but it is much more readily accomplished with a computer. A program to accomplish this, given in listing 1, is written in a nearly universal dialect of BASIC.

An important point is that the utility of the procedure is based on the assumption that the "noise" apparent in figure 1 is truly a random fluctuation independent of the signal (or month). In principle, it is possible for the month-to-month sales volume to be totally deterministic

Text continued on page 276

6000

_

5000 4000

/ x^* / 1 s\ / Is 'v /

-A

K

3000

/'I

2000

s

1000

1

1 1 1 1

i i

Listing 1 continued on page 266

JFMAMJ JASOND

MONTH IN 1978

Figure 1: Chart of sample data used in this article. The data plotted in this chart, drawn in a solid line, represents the sales of a hypothetical company for the months January through December 1978. The broken line is a human-drawn estimate of the ideal numbers that the given data roughly represents.

264 March 1981 © BYTE Publications Inc

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SPELLGUARD is Easy to Use

• proofreading capabilities are mastered in a few minutes.

• comprehensive user's manual contains step-by-step examples of all SPELLGUARD features.

SPELLGUARD is Powerful

• text files to 85 pages (CP/M 1.4), and 2,800 pages (CP/M 2.0). includes a 20,000-word, expandable dictionary.

• contains powerful commands to construct customized dictionaries for special areas, e.g., medicine, real estate, law, insurance, engineering.

SPELLGUARD is Reliable

• thoroughly tested in actual use with free one-year maintenance service.

• 30-day money-back limited warranty.

• includes computer program for software updates and maintenance.

Minimum System Requirements: 8080/85. Z80 CPU with 32K memory: CP/M' 1.4 (dictionaries to

256K bytes), CP/M' 2.0 or later (dictionaries to 4 MB), or CDOS; word processor or text editor

compatible with SPELLGUARD (currently several excellent new CP/M word processors, and

WordStar". WordMaster, Magic Wand:1. Electric Pencil1, and ED).

Trademarks: 'Digital Research (registered). -MicroPro lnt'1 Corp.. 'Small Business Applications.

'Michael Shrayer Software. "'Cromemco.

"Time estimates based on 4Mhz 8085 with 48K memory. CP/M 2.1 double density 8" floppy drive,

10,000-word text file.

The price of SPELLGUARD includes rapid turnaround and delivery by UPS or airmail. Sales will be made only if the purchasers' word processor is compatible with SPELLGUARD. Software license agreement is required.

□ Send me a free, detailed description and latest diskette format availability.

□ Send me SPELLGUARD at $295.00. (Manual and diskette(s). Formats: 8" CP/M single density Shugart compatible, and 5'A" Northstar double.)

□ Send me copies of the

SPELLGUARD manual at $20.00 each. (Airmail, credited toward purchase.)

D Send COD (add $10.00 handling).

California residents add 69c tax.

Add $10.00 for foreign shipment.

Check enclosed for $ .

(Certified check, COD, and money order shipped immediately.)

ORGANIZATION

WORD PROCESSOR

COMPUTER SYSTEM

DISK FORMAT

Checks pay Box 2797.

ayable to ISA . I ', Menlo Park, CA 94025. I

INNOVATIVE SOFTWARE APPLICATIONS

Box 2797, Menlo Park, California 94025 415-326-0805

(Dealer inquiries invited.)

STATE-OF-THE-ART SOFTWARE

Circle 177 on inquiry card.

BYTE March 1981

265

Circle 178 on inquiry card.

i«r<\ system?, ma.

No. P7 Zenith Data Systems Z89F Microcomputer with Z47 8" Dual Disk Drive

ZENITH DATA SYSTEMS LIST OCR PRICE

Z89-FA Microcomputer System $2,895 $2,495

48KB, 5.25' Disk, HDOS Z89-GA Microcomputer System $2,595 $2,259

48KB, HDOS (No Disk)

Z19 CRT Terminal SPECIAL $ 950 $ 795

Z87 Dual 5.25'Disk Unit (200 KB) $1,195 $1,095

Z47-BA Dual 8" Disk Unit (2MB) NEW $3,695 $3,295

CP/M® V.2.2 for Z89 $ 150 $ 140

HDOS Operating System (with BASIC) $ 150 $ 140

Microsoft BASIC V5.1 for CP/M $ 175 $ 160

Microsoft BASIC V5.1 for HDOS $ 150 $ 140

Microsoft FORTRAN $ 195 $ 180

Microsoft COBOL $ 395 $ 350

Word Processing for Z89 $ 395 $ 375

To Order: Send Check or Money Order to: PK Systems, Inc., 113 North

Center, Bloomington, IL 61701 Allow two weeks for personal checks to clear.

For COD Orders, add 5% for handling and service charge. Rush orders, add

$50.00.

Shipping: Freight collect, FOB Bloomington. We ship UPS, air freight, or

motor freight.

PK Systems is an Authorized Zenith Data Systems Dealer and Zenith Service

Center. P^S3B i

5(JC£J£EEiS3 C'M 's a trademark of Digital Research

MULTIPATH TREE

KEY FILE SYSTEM

RUNS ON UCSD*

PASCAL

Locate 1 Key Element in 32,000 + in Under 3 Disk Accesses

Library procedures Allow You To:

INSERT DELETE FIND NEXT RANGE

Optional Procedures For:

CREATE PRINT TREE

One single density 8 inch disk (others available) contains 24 variationsuse the one best suited to your application.

Also available using this key system are high performance business, engineering, system and personal software packages. Write for more information and catalog.

Diskette plus Documentation $90.00

Please specify type of system and version operating system.

KeeSoft, Suite 1351, 10 Milk St. Boston, MA 02108

•TM Univ. Of Calif.

Listing 1 continued:

74 NEXT K

77 PRINT

78 GOSUB 535

79 PRINT *TH

80 PRINT 'BE

81 PRINT "UN

82 PRINT D

83 PRINT

84 GOSUB 535

85 REM PLOT

86 FOR K = l T

87 D(K)--=ABS<

88 NEXT K

89 REM GO TO

90 PRINT

91 PRINT

92 GOSUB 472

93 PRINT 9 4 PRINT 95 PRINT 9 4 END

97 REM *****

98 REM DATA

99 REM VISOR

100 REM IT I

101 REM B,C,

102 REM HAVE

103 REM DIME

104 REM B(

105 REM C< 104 REM D(

107 REM U(

108 REM V(

109 REM U(

110 REM Y<

111 REM Yl

112 REM IT I

113 REM THE

114 REM AVAI

115 REM N

116 REM Y

117 REM THE

118 I=N1

119 J=N2

120 REM THE

121 REM FIRS

122 FOR K=l 12 3 Y 1 ( K ) - 0

124 NEXT K

125 REM DETE

126 GOSUB 16

127 REM DETE

128 GOSUB 19

129 REM ERRO

130 IF E>0 T

131 REM 0BTA

132 REM

133 REM

134 GOSUB 22

135 REM SAVE

136 REM NORM

137 U=U(B(Ii

138 A=(N3-1>

139 V=V(B<If

140 REM GET

141 GOSUB 37

142 REM CREA

143 REM DATA

144 GOSUB 41

145 REM SMOO

146 REM THE

147 REM IS M

148 FOR M^A +

149 GOSUB 43 15 0 Y 1 (M)= D

151 NEXT M

152 REM SHIF

153 GOSUB 45

154 REM RESU

155 REM GET

156 GOSUB 45

157 REM RESU

158 PRINT

E STANDARD DEVIATION" TUEEN THE SMOOTHED AND" SMOOTHED DATA SETS IS".

ABSOLUTE UALUE OF RESULTS 0 N4 Y 1 ( K > )

PLOTTING SUBROUTINE

OOTHER SUPER

UBROUTINE

ASSUMED THAT

U.V.U.Y AND Yl

LREADY BEEN

IONED.

3)

91)

+ 2 * N 3 + 2 )

12)

)

)

4)

ALSO ASSUMED THAT

PUT DATA IS

BLE

N2rN3iN4

)

OGRAM USES I AND J

OUTPUT IS Y1(K >

T INITIALIZE Y1CK)

TO N4

RMINE THE TABLE

9

RMINE IF ERROR

7

R ON E>0

HEN RETURN

IN COEFFICIENTS

U(I)>V(I>J)

C(I.K)

5

THE SYMMETRY AND ALIZING FACTORS J) ) /2

J) , 13-A) UEIGHTS. U(K) 5 TE AUGMENTED

V E C T 0 R . D ( K ) 9

TH THE DATA VECTOR IKK) DATA POSITION POINTER

1 TO N4+A+1 9

T YKM) DOWN

2

LT IS YKM)

STANDARD DEVIATION

9

LT IS D

Listing 1 continued on page 268

266 March 1981 © BYTE Publications Inc

Circle 179 on inquiry card.

MEMORY PRODUCTS FOR THE80'S

16K Byte—Fully Static

8/16 RAM

Designed with the Future in Mind—

Able to use the full 24-bit address bus of the IEEE S-100 Standard for a 16-megabyte address range.

Fully static design eliminates system timing problems. Promotes reliable operation with a wider range of CPU cards and DMA devices.

Easy to integrate into your system. Addressable on 4K boundaries. PHANTOM, extended addressing, 16-bit operation may be switched off if desired.

• Can act as either an 8-bit or 16-bit wide memory. Dynamic bus switching per the IEEE Standard.

• Fast 200 nanosecond memory chips help you keep up with the ever-rising clock speeds of newer CPUs.

• The 8/16 is the only memory board made which is designed to run at full speed with our 16-bit 8Mhz. 8086 CPU card. And, it has plenty of speed to spare.

From Seattle Computer, the Static Memory Experts

Why static memory? First, compatibility. Most S-100 products do not meet the IEEE Standard. Because of their critical timing requirements, dynamic memory boards must often be configured for a particular CPU — a situation that could make future upgrading difficult. Static memories are inherently more versatile.

Second, speed. The access times of static and

dynamic memories are not comparable numbers. Static memories get a substantial head start while dynamic memories wait for a "clock." The IEEE S-100 Standard guarantees this head start is at least 70 nanoseconds. The result: most of today's dynamic memory boards will not run at full speed with tomorrow's (or even today's) faster CPUs. The 8/16 will.

The 8/16 memory card is fully assembled, tested, guaranteed one full year. Suggested retail price: 1 -4, $395; 5-9, $345. Manual only — $3. Overseas purchasers add $15 per board for air shipment.

Circle 180 on inquiry card.

A

y Seattle Computer Products, Inc.

*-*--* 1114 Industry Drive, Seattle, WA. 98188

(206) 575-1830

BYTE March 1981

267

Circle 181 on inquiry card.

wmlmm

Color Computer 4K S310

Pocket Computer $ 199

Model III 16K \ S859

These are just a few of our many fine offers — computers, peripherals, modems, printers, disc drives and an unusual selection of package values. Call TOLL FREE today and check us out for price and warranty.

Pure Radio Shack equipment warranteed 1 al any Radio Shack store or dealer' Factory warrantees on Apple and Atari equipment. Other equipment carries manufacturer's warranty or Computer Plus 180 day extended warranty. Combined warrantees carry Computer Plus 180 daywarranty or original manutacturer'swarranty.

DEALER INQUIRIES ARE INVITED

Prices subject to change without notice.

TRS-80 is a registered trademark ol Tandy Corp.

Call TOLL FREE

1-800-343-8124

computer 'plus1

Write for your free catalog

Dept. E

245A Great Road

Littleton. MA 01460

(617)486-3193

178 REM E=l

179 REM E=2

180 REM E=3

181 REM

182 REM E=4

183 REM E=5

184 REM

185 REM E=6

186 REM E = 7

187 REM E=8

Listing 1 continued:

1 J V Ktn V V *(t It *(t It * If * *|C 1^ It 3|t 3|t )(t Jft)((J(t 3(C Jf(

160 REM TABLE DECODE SUBROUTINE

161 REM THERE ARE 8 TABLES OF

162 REM COEFFICIENTS TO BE CHOSEN

163 REM ACCORDING TO THE DEGREE OF

164 REM FIT, I> AND THE DERIVATIVE

165 REM LEVEL, J. THE DECODING

166 REM ARRAY IS B < I , J ) .

167 REM NEW TABLES 12 AND 13

168 REM ARE MOVED TO 5 AND 3

169B(1,0)=5\B(1,1)=3\B(1,2)=0\B<1,3)=0\B<2,0>=1\B(2,1)=3 170B(2,2>=6\B<2,3>=0\B<3,0)=1\B(3,1>=4\B(3,2>=6\B<3,3)=8 171B(4,0>=2\B(4,1)=4\B(4,2>=7\B(4,3)=8\B(5,0)=2\B<5,1>=0 172B(5,2>=7\B<5,3)=0

17 3E<1>=5\E<2)=7\E(3)=3\E(4)=5\E(5)=3\E<6)=5\E(7)=5\E(8>=5

174 RETURN

175 REM ********************

176 REM ERROR CODING SUB.

177 REM E=0 - NO ERROR TOO FEU POINTS TOO MANY POINTS DERIVATIVE > FIT LEVEL

FIT TOO HIGH DERIVATIVE TOO HIGH

TABLE NOT AVAIL. NOT ENOUGH DATA ILLEGAL VALUE

188 REM N1=LEVEL OF FIT

189 REM N2=0RDER OF DERIVATIVE

190 REM N3=N0. OF DATA POINTS

191 REM TO BE AVERAGED

192 REM N4=T0TAL DATA SET SIZE

193 E=0

194 IF B(N1,N2>=0 THEN E=6

195 IF NKO THEN E = 8

196 IF N2>3 THEN E = 5

197 IF N3<3 THEN E>1

198 IF N3:;25 THEN E»2

199 IF N3<E(B(N1,N2>) THEN E-1

200 IF N2>N1. THEN E = 3

201 IF N2<0 THEN E=0

202 IF INT (N3/2)=N3/2 THEN E-B

203 IF N3>N4 THEN E^7 20-1 IF Nl>5 THEN E-A

205 RETURN

206 REM *******************

207 REM COEFFICIENT STORAGE SUB.

208 REM THE WEIGHTS ARE STORED IN

209 REM THE ARRAY C<I , Iw . THE IN

210 REM DEX, Ii REPRESENTS THE

211 REM TABLE NUMBER (1 TO 8).

212 REM THE INDEX, K, REPRESENTS

213 REM THE ELEMENT IN TABLE I.

214 REM THERE ARE UP TO 91 SUCH

215 REM ELEMENTS.

216 REM ALSO STORED ARE THE NORM

217 REM ALIZING FACTORS, V (I, K >,

218 REM WHERE K RANGES FROM 1 TO

219 REM 13. IN ADDITION, THE 3

220 REM SYMMETRY VALUES, U(I>,

221 REM ARE ALSO INCLUDED.

222 REM NOTE THAT TABLES 12 (NOW 5)

223 REM AND 13 (NOW 3) ARE CALCULATED

224 REM ELSEWHERE.

225U(1 )-l\l.l(2)=l\U(3)=-:l \U(4)=-1\UC5) = 1\U(6) = 1\U(7) = 1\U(8)=-1

226V(1,1)=5175\V(1,2)=805\V(J. ,3)=3059\V( 1,4) =2261

2 2 7V (1 ,5>=323\V(1 , 6 ) = :l. 105W (1,7)-143\V< 1 , B ) =429\V (119 ) '=231

228V(l,1.0)=21\V(l,ll)=35\V(2,l) = 3 001.5\V(2,2)-6555

229V(2,3>=260015\V(2,4)=7429\V(2,5}=<U99\Vl2,6)=46189

230V(2,7>=2431\V(2,8)=429\V(2,9)=429\V(2,101=231

231V(4,l) = 1776060\V(4,2) = 197340\V(4,3i=3634092\V(4,4)=255B1.6

232V(4,5)=23256\V(4,6)=334152\V(4,7) = 24024\V(4,8)=:;il4£)

233V(4,9) = 11B8\V(4,10)=252\V(4,1.1. ) = :I2

234V(6,1. )=26910\V(6,2)=17710\V(6,3)=33649\V(6,4)=6783

235V(6,5)=3876\V(6,6)=6188\V(6,7)=1001\V(6,8)=429\V(6,9)=4 62

236V(6,10)=42\V(6,11)=7\V(7,11=4292145\V(7,21=2812095

237V(7,3)=245157\V(7,4)=490314\V(7,5)=4 78686\V(7,6)=2 77134

238V(7,7)=160446\V(7,B)=16731\V<7,9)=4719\V(7,10)=99\V(7,11)=3

239V(8,1)=296010\V(B,2)"32890\V<8,3)=86526\V(8,4)=42636

24 0V(8,51=3876\V(8,61=7 956\V(8,71=572\V(8,81=858\V<8,91=198

241V(8,10)=6\V(8,11)=2

242I-URK = 1T012\V(5,K1=27-2*K\V(3,.1.3-K1=K*<K+11*(2*Kt1 )/3\NEXTK

Listing 1 continued on page 270

268 March 1981 © BYTE Publications Inc

Circle 182 on inquiry card.

Can your

word processor

pass this screen test?

WordStar™ software does*! And does it better than any other word processing system. Not only do you get all the sophisticated features youd expect from the high-priced WP system, with WordStar you have a true screen image of what your printout will look like before you print it!

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displayed and automatically revised on the screen. You can specify enhancements like underlining and boldfacing, and much more.

And WordStars so much easier to learn because of its unique and extensive self-help menus. Every typist in your office can be an instant screen star. Call (415) 457-8990 and ask for a copy of our WordStar demon

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ici@PfO,

INTERNATIONAL CORPORATDN

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"Runs on most Z80/8080/8085 microcomputers with CP/M (TM of Digital Research); 48K, and terminal with addressable cursor

Circle 183 on inquiry card.

^M BC Systems, Inc^

(203) 342-2747

f

«j „_, - VHP "

! ■

1

IJCRTH STAR HORIZON:

4$2275

KRZ-2-32K-D-Factory AS

HRZ-2-32K-Q-Factory ASM$2675

64K DD or Q Also Avail

able

HDS-18-F

.54449

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$ 359

.$ 365

. $ 269

. ? 775

ACC. REC. OR ACC. PAY.

. S 445

.? 350

Medical-Dental SYS....

$2500

EHB> ■■w.w.-.wa jm

COMMODORE (PET):

$1090

2001-32K-BorN Keyboard

16K Also in Stock..

.$859!!!

8032 (80 Column Screen)$1599

2040 Dual Floppy Drive

$1090

8050 Dual Floppy (1MEG)S1599

2022 Tractor Printer..

.$ 749

Word PRO IV

. $ 290

VISICALC

.$ 195

APPLE II PLUS Call For

Price !

$ 849

. $990

ATARI 800

TI 99/4 Console&Monitor.

INTERTEC SUPERBRAIN:

$2595

32K RAM

64K RAM

$2695

PRINTERS

Letter Quality:

NEC 5510 or 5530

$2550

NEC 5520 KSR

.$2950

DIABLO 630

$2390

C.ITOH

.$1690

Dot Matrix:

CENTRONICS 730

$ 599

737-1

$ 799

799

$ 999

EPSON MX-80

$ 599

PAPER TIGER 460G

$1250

BASE II MST

$ 649

DISPLAY TERMINALS

HAZELTINE 1420

$ 949

" " 1500

$ 999

ItJTERTUBE III

$ 775

TELEVIDEO 920C

$ 849

Since 1977 complete sales and

service. Most items in stock.

prices are subject to change.

Visa and Master Charge welcome

Most items shipped by UPS.

MBC Systems, Inc.

Multi Business Computer Systems, Inc.

28 MARLBOROUGH STREET

PORTLAND, CONN. 06480

(203)342-2747 TWX 710-42E

-6345

L M-F 9-6 SAT.9:30-3:0C

A

Listing 1 continued:

243FDRK=1T0.12\V<7»K> = 12*VC7,K)\NEXTK

244C<1.1)=467\C<1>2)=462\C<1.3)=447\C<1>4)=422\C<1>5)=387

245C(1.6)=342\C<1.7)=287\CU»8)*'222\C<1»9)=147\C<1,10>=62

246C<l>ll)=-33\C<l»i2)=-138\C<i»13)=~253\C<l>14)=79\C<l>15>=78

247C<1,16)=75\C<1,17)=70\C<1,18)=63\C<1,19>=54\C<1,20>=43

248C<l>2i)=30\C(l>22)=15\C(1.23)=~2\C<i»24)=-21\C<:l. .25)=~42

249C<1,26>=329\CC1,27>=324\C<1,28)=309\C<1,29)=284\C(1,30>=249

250C(l>31)=204\C(1.32)=149\C<1.33)=84\C(l»34)=9\CU»35>=-76

251C<1.36)=-171\C(1.37)=269\CC1.38)=264\C(1.39)=249

252C(1.40)=224\C(1.41)=189\C(1.42)=144\C(1.43)=89\C(1.44)=24

253C<1.45)=-51.\C<1>46)=-136\C<1.47)=43\C<1»48>=42\C(1>49)=39

254C(1.5 0)=34\C(1.51)=27\C(1.52)=18\C(1.53)=7\C(1.54)=-6

255C<1»55)=-21\CU.56)=167\C(1.57)=162\C(1.58)=147\C<1»59>=122

256C<1.60)=87\C<1.61)=42\CU.62)=-i3\CC1.63)=-78\CCl»64)=25

257C(l,65)=2 4\C<l,66)=21\C<l,67)=16\CU,68)=9\Ctl,69>=0

25BC<1,70>=-11\C<1,71)=89\C(1,72)=84\C<1,73)=69\C(1,74)=44

259C<1.75)=9\C<1.76)=-36\C<1.77) = 59\C<1.78)=>54\C<1»79)=39

260C(1.80)=14\C(1.81)=-21\C<1»82)=7\C(1.B3)=6\C(1.84)=3

261C(1,85)=-2\C(1,86)=17\C(1,87)=12\C<1,88)=-3\C<2,1)=4253

262C(2.2)=4125\C<2,3)=3750\C(2.4)=3155\C(2,5)=2385\C(2,6) = 1503

263C(2,7)=590\CC2,8)=-255\C<2,9)=-915\C<2,10)=-1255

264C(2,11)=-1122\C<2.12)=-345\C<2»13)=1265\C(2»14)=1011

265C(2.15)=975\C(2,16)=B70\C(2,17)=705\C(2,18)=495\C(2,19>=2 61

266C(2,20)=30\C(2,21)=-165\C<2,2 2>=-2 85\C(2,23)=-285

267C(2,24)=-114\C(2,25)=285\C(2,26)=4 4003\C<2,27)=42120

26BC(2,28)=36660\C(2,29)=28190\C(2,30)=17655\C(2,31)=6378

269C<2,32)=~3940\C(2,33)=-11220\C(2,34)=-13005\C<2,35)=-6460

270C(2,36)=11628\C(2,37>=1393\CC2,38)=1320\C(2,39)=1110

271C<2»40)=790\C(2»41)=405\C<2,42)=18\C<2,43)=-290

272C(2,44)=-420\CC2,45)=-255\C(2,46>=340\C<2,47)=883

273C<2,4B)=825\C(2,49)=660\C<2,50)=415\C<2,51)=135

274C(2,52)=-117\C<2,53)=-260\C(2,54)=-195\C<2,55)=195

275C(2,56)=11063\C(2,57)=10125\C(2,58)=7500\C(2,59>=3755

276C<2,60)=-165\C(2,61)=-2937\C<2,62)=-2860\C<2,63)=2145

2 77C<2,64)=677\C(2,65)=600\C(2,66)=390\C(2,67>=110 278C(2,68)=-135\CC2,69)=-198\C(2,70)=110\C(2,71)=143 279C(2,72)=120\C(2,73)=60\C(2,74)=-10\C(2,75)=-45\C(2,76>=18 280C(2,77)=179\C<2,78)=135\C<2,79>=30\C<2,80)=-55\C(2,81)=15 281C(2,82)=131\C<2,83>=75\C<2,84)=-30\C<2,85)=5 282C(4,l)=0\C(4,2)=-8558\C<4,3)=-16649\C<4,4)=-23806 283C<4,5)=-29562\C<4,6)=-33450\C<4,7)=-35003\C<4,8)=-33754 284C(4,9)=-29236\C(4,10)=-20982\C(4,11)=-8525\C<4,12)=8602 285C<4,13)=30866\C<4,14)=0\C<4,15)=-1222\C(4,16)=-2365 286C<4.17>=-3350\C(4,18>=-409B\C(4,19>=-4530\C<4,20>=-4567 287C(4,21)=-4130\C(4,22)=-3140\C<4,23)=-1518\C(4,24)=815 28BC(4,25)=3938\C<4,26>=0\C<4,27)=-29592\C<4,28)=-56881 289C(4,29)=-79564\C(4,30)=-95338\C<4,31)=-101900 290C(4,32)=-96947\C<4,33)=-78176\C(4,34)=-43284\C<4,35)=10032 291C(4,36)=84075\C(4,37)=0\C<4,38)=-2816\C<4,39)=-5363 292C(4,40) = -7372\C(4,41)=-8574\C<4,42)=-8700\C(4,43)=--7481 293C(4,44)=-4648\C(4,45)=6 8\C<4,46)=6936\C<4,47)=0 294C(4,48)=-358\C<4,49)=-67 3\C<4,50)=-902\C<4,51)=-1002 295C(4,52)=-930\C(4,5 3)=-643\C<4,54)=-98\C<4,55)=74B\C(4,56>=0 296C < 4,57 )=-7506\C< 4,58 >=-13843\C< 4,59 )=-.1.7842\C( 4, 60) = -18334 297C(4,61)=-14150\C(4,62)=--4121\C<4,63) = 12922\C(4,64)=0

298C(4,65)=-832\C(4,66)=-1489\C(4,67)=-1796\C(4.68)=-1578

299C(4,69)=-660\C(4,70)=1133\C(4,71)=0\C(4,72)=-296

300C(4,73)=-503\C(4,74)=-532\C(4,75)=-294\C(4,76)=300

3 01C(4,77)=0\C(4,78)=-126\C<4,79)=-193\C(4,80>=-142\C(4,81>=86 302C(4,82)=0\C(4,83)=-58\C(4,84)=-67\C(4,85)=22\C<4,86)=0 303C(4,87)=-8\C(4,88)=l\C(6,l)=-52\C(6,2)=-51\C(6,3)=-48 304C<6,4)=-43\C(6,5)=-36\C(6,6)=-27\C<6,7)=-16\C(6,8)=-3 305C(6,9)=12\C<6,10)=29\C(6,11)=48\C(6,12)=69\C(6,13)=92 306C<6.14>=-44\C<6.15)=-43\C(6.16)=-40\C(6,17)=-35\C<6,18)=-28 307C<6,19)=-19\C(6,20)=-8\C(6.21)=5\C(6,22>=20\C(6.23>=3 7 308C(6,24) = 56\C(6,25)=77\C(6,26)=-110\C(6.. 27)=-107\C<6,28)=-98 309C(6,29)=-83\C(6,30)=-62\C<6,31)=-35\C<6,32>=-2\C16,33>=37 310C(6,34)=82\C<6,35)=133\C(6,36)=190\C<6,37)=-30\C(6,38)=-29 311C:(6,39)=-26\C(6,40)=-21\C(6,41)=-14\C(6,42) = -5\C(6,43)-A 312C<6,44)^19\C(6,45)=34\C(6,46)=51\C(6,47)=-24\C(6,48)=-23 313C:(6,49) = -20\C(6,50)=-15\C(6,51)=-8\C(6,52) = 1\C(6,53)-12 314C(6,54)=25\C(6,55)=40\C(6,56)=-56\C(6r57)=-53\C(6,58)=-44 315C(6,59)=-29\C(6,60)=-8\C(6,61)=19\C(6,62)=52\C(6,63)=91 316C(6,64)=-14\C(6,65)=-13\C(6,66)=-10\C<6,67)=-5\C(6,68)=2 317C<6,69)=ll\C(6,70)=22\C(6,71)--10\C(6,72)=-9\C(6,73)=-6 31BC(6.74)=-1\C(6,75)=6\C(6,76)=15\C(6,77)=-20\C<6,78)=-17 319C(6.79) = -8\C(6,80) = 7\C(6.81)--2B\C(6,82)=-4\C(6,83)=-3 320C(6,84)=0\C(6,85)=5\C(6,86)=-2\C(6,87)=-1\C(6,88)=2 321C(7,1)=-4418 70\C(7,2)=-418011\C(7,3)=-348429\C(7,4)=-239109 322C(7,5)=-100026\C(7,6)=54855\C(7,7)=207579\C(7,8)=336201 323C(7,9)=414786\C<7,10)=413409\C(7,11)=298155\C(7,12)=31119 324C(7,13)=-429594\C<7,14)=-373230\C(7,15)=-349401 325C(7,16)=-280275\C(7,17)=-172935\C(7,18)=-39186 326C:<7,19) = 104445\C(7,20)=236709\C(7,21)=331635\C<7,22) =358530

Listing 1 continued on page 272

270 March 1981 © BYTE Publications Inc

'■:•*■ ■ I %i?: -Jags™ #w£^TS

Great software doesn't have to be hard to find.

Just look for

the Hayden name.

SARGON II (Spracklens) The Champ of champs ". - .an excellent program which will provide a true challenge for many players... Save your money and buy SARGON II..." W Software Critique. 03403. TRS 80 Lei-el 11:03404. Apple II: 03410. OSI C1P: 03440, OSI C4P: 03401. PET: each (ape $29.95. 03408. TRS 80 Level II Disk: 03409. Apple II Disk: 03414. OSI CIP Disk: 03444. OSI C4P Disk: 03484. C8P Disk: each S34.9S

BLACKJACK MASTER: A Simulator Tutor Game (Wazaney) A serious game that performs complex simulations and evaluations of playing and belting strategies 05303. TRS 80 Level II tape. S24 95. 05308. TRS 80 Disk Version. $29 95

REVERSAL (Spracklen)

Winner of the software division of the Firsf Inter

national Man Machine OTHELLO'" Tournament.

this version of the 200-year old game Reversi .features

27 levels of play and high resolution color graphics

07004. APPLE II tape. $29.95: 07009. APPLE II Disk.

S34.9S

APPLESOFT UTILITY PROGRAMS (Gilder) Increase your BASIC programming speed and llexi bility Contains 9 useful subroutines: 1. REM Writer 2. PRINT Writer 3 POKE Writer 4. Hexadecimal Decimal Converter 5 Line Counter 6. Renumber 7. Append 8. Byte Counter 9. Slow List Stop List 03504. Apple II tape. S29.95

ENERGY MISER (SuperSofl Associates) A complete healing cooling analysis program for your home or office that will calculate heat loss or gain due to poor insulation, leaky doors and windows, and more. 05601. PET: 05603. TRS 80 Level II: 05604, Apple //; each tape $24.95: 05609. Apple II Disk Version: 05613. Heathkit/Zenith Disk Version: S29.95

6502 DISASSEMBLER (Slamm) Produce assembly language source files with labeled subroutines and references from programs already in memory. It is compatible with Hayden's ASSEM BLY LANGUAGE DEVELOPMENT SYSTEM. 08609. APPLE II Disk. $34 95

PSEUDODISK (Neuschatz)

This money saving program simulates a disk memory

system for Integer BASIC programs. It allows mulli

pie programs in memory at the same time which

can be run from a catalog 04804, APPLE II tape.

$24.95

L1NE& VARIABLE CROSS REFERENCE GENERATOR (Johnson) Provides a cross refer ence of line numbers and variable names. 07301. PET tape. $16.95

DISK CATALOGER (LeBar) Automaticallymaintainsa cross-reference listing of all your programs, their location by disk number, their function and use. Catalogs, lists and sorts programs 05203. TRS-80 Level II tape. $16.95: 05208. TRS 80 Level II Disk. $21.95

APPLE'" ASSEMBLY LANGUAGE DEVELOPMENT SYSTEM: An Assembler/Editor Formatter (Lutus) Write and modify your machine language programs quickly and easily 04609, Apple 11 Disk Version. $39.95

SUPER APPLE'" BASIC (Lutus) A structured BASIC that compiles into an optimized Applesoft or Integer BASIC program. 05409. Apple II Disk. $39.95

MAILING LIST (Tru Data Software) Lists addresses, prints labels, allows for alterations and deletions, and has the capacity to make duplicate data file disks. Can only be used with version 1.5. 05713. Heath Disk, $49.95

ORDERING INFORMATION

Send me the software checked below. A check or money order is enclosed. 1 understand thai Hayden pays shipping and handling costs and that 1 can return any disk or tape within 10 days if it is defeclive or I am dissatisfied with it for any reason Residents of NJ and CA must add sales tax. Offer good in US only.

D 03401 □ 03414 □ 0450M

D 03403 □ 03440 □ 04504

G 03404 D 03444 □ 045 13

D 03408 D 03484 □ 04509

D 03409 G 03504 □ 04804

G 03410 G 04501 G 0490Q

Book Company, Inc.

50 Essex Street, Rochelle Park, N J 07662

n

on inn

D

OZ404

D

01401

D

02501

D

01403

D

02503

n

01404

n

02601

D

01407

D

02701

D

01413

D

03304

D 05105 D 05108 □ 05203 D 05208 D 05308 D O540'J

D 05603 D 05604 a 05609 D 05613 D 07004 D 07301

D 07809 D 08609 D 5681 8

Name

Add ress

City/Stale/Zip

Name of individual ordering must be filled in.

B 3/81

FINPLAN: A Financial Planning Program for Small Business (Montgomery) Allows you to enter data from a balance sheet into the program, to make assumptions about future growth of business, and to have the computer project results for up to a five year period based on those assumptions. And if you change any data, the program revises all result ing data automatically. The disk version can only be used with TRSDOS Version 2 3. 05103, TRS 80 Leuel II tape, S69.95; 05108. TRS 80 Level II Disk Version, S74.95

DATA MANAGER: A Data Base ManagemenI System and Mailing List (Lutus) Store information on a floppy disk, and retrieve it quickly and easily by specific names, or by category. 04909, Apple 11 Disk Version, $49.95

MCAP: A Microcomputer Circuit Analysis Program (Savon) Performs a linear voltage, impedance, or transfer impedance analysis of an electronic circuit. 04501. PET;04503, TRS-80 Level II; 04504. Apple II; each tape $24.95; 04513. Heathkif Zenith Disk, S29.95

MICROCOMPUTER AIDED DESIGN OF ACTIVE FILTERS (Gilder) Eight programs that simplify the design of active filters and will calculate the component values needed for various bandpass, low-pass, and notch-type filters. 0J40J. PET; 01403, TRS-80 Level II; 01404. Apple 11; 01407. Heath; each tape S16.95; 01413. Healhkit Zenith Disk Version, S21.95

DISK CERTIFIER AND COPIER (Jacc Inc.) A handy utility program that certifiesthe acceptability of blank diskettes and rejects those with flaws. It alsoincludesafast machine language disk copying program that will work on single and dual drive svs\ems.07809. APPLEII Disk. S19 95

SONGS IN THE KEY OF APPLE (Lopatin) Allowsyouto see and hear your favorite tunes, pre programmed tunes or music you create (up to 200 notes, including rests, per musical piece). 03304. Apple II tape. S10.95

HOW TO BUILD A COMPUTER-CONTROLLED ROBOT (Loofbourrow) Contains 5 control programs that consist of: Joystick Control Program; Self Direction Program; Impact Sensor Control Routine; and more. 00100.KIM 1 tape.$14.95 Should be used with text HOW TO BUILD A COMPUTER-CONTROLLED ROBOT, 5681 8. S9.75

Apple is a trademark o I Apple Computer Company, It

and is no/ alfilialpd with Harden Bonk Co"i/)unv. mi'.

Call Toll Free,

24 hours a day,

(1-800-821-3777. ext. 302)* TO CHARGE YOUR ORDER TO Master Card or Visa. Minimum order is $ 10.00; customer pays postage and handling. From Missouri call (1 800 892-7655, ext. 302)

50 Essex Street, Rochelle Park, NJ 07662

Book Company, Inc.

Circle 184 on inquiry card.

BYTE March 1981 271

Circle 185 on inquiry card.

MTI stocks 'em all for faster delivery.

No hidden charges. Prices include delivery.

Ask about our"QED" discounts.

VISA and MasterCard orders accepted.

VIDEO TERMINALS

VT100 DECscope $ 1695

VT132 DECscope 2295

ADM-3A (dumb terminal) •

ADM-3A+ (dumb terminal) •

ADM-31 (2 page bufferl •

ADM-42 (8 page buffer avail.) •

1410 (Hazeltine dumb terminal) 825

1420 (dumb terminal) 895

1421 (Consul 580 & ADM-3A comp.I.... 895

1500 (dumb terminal) 1045

1510 (buffered) _ 1145

1520 (buffered printer portl 1395

1552 (VT-52 compatible] 1350

300 BAUD TELEPRINTERS

LA34-DA DECwriter IV 1045

LA34-AA DECwriter IV 1295

Teletype 4310 1085

Teletype 4320 1225

Diablo 630 RO 2295

Diablo 1640 RO 3085

Diablo 1640 KSR 3285

Diablo 1650 RO 3185

Diablo 1650 KSR 3385

Tl 743 (portable) 1190

Tl 745 (portable/built-in coupler) 1585

Tl 763 (portable/bubble memory) 2690

Tl 765 (port/bubble mem/b-i coupler) . 2895

600 BAUD TELEPRINTERS

Tl 825 RO impact 1565

Tl 825 KSR impact 1645

Tl 825 RO Pkg 1750

Tl 825 KSR Pkg 1895

1200 BAUD TELEPRINTERS LA120AA DECwriter III (formspkg.) . 2410

LA180 DECprinter I 2195

Tl 783 (portable) 1745

Tl 785 (port/built-in couplerl 2395

Tl 787 (port/internal modem) 2845

Tl 810 RO impact 1800

Tl 810 RO Pkg 2047

Tl 820 KSR impact 1895

Tl 820 KSR Pkg 1995

Tl 820 RO 1895

Tl 820 RO Pkg 2047

2400 BAUD

Dataproducts M200 (2400 baud) 2595

DATAPRODUCTS LINE PRINTERS

B300 (300LPM band) 5535

B600 (600LPM band) 6861

2230 (300LPM drum) 7723

2260 (600 LPM drum) 9614

2290 (900LPM drum) 12655

ACOUSTIC COUPLERS

A/J A242-A (300 baud orig.) 242

A/J 247 (300 baud orig.) 315

A/J AD342 (300 baud orig./ans.) 395

A/J 1234 (Vadic compatible) 895

A/J 1245 (300/1200 Bell comp.) 695

MODEMS

GDC 103A3 (300 baud Bell) 395

GDC 202S/T (1200 baud Bell) 565

GDC 212-A (300/1200 baud Bell) 850

A/J 1256 (Vadic compatible) 825

CASSETTE STORAGE SYSTEMS

Techtran816 (store/forward) .1050

Techtran 817 (store/for/speed up) 1295

Techtran818 (editing) 1795

Techtran 822 (dual) 2295

MFE 5000 (editing) 1495

FLOPPY DISK SYSTEMS

Techtran 950 (store/forward) 1395

Techtran 951 (editing) 1995

•Please call for quote.

mti

Applications Specialists & Distributors Great Neck. New York/Cleveland Ohio.

N.Y.: 516/482-3500 & 212/895-7177 800/645-801& Ohio: 216/464-6688

Listing 1

327C(7

328C<7

329C<7

330C(7

331C(7

332C(7

333C(7

334C(7

335C(7

336C<7

337C<7

338C(7

339C<7

340C(7

341C<7

342C<7

343C<7

344C<7

345C(8

346C<8

347C(8

348C(8

349C(8

350C<8

351C(8

352C<8

353C<8

354C(8

355C<8

356C<8

357CC8

358C<8

359C<8

360C<8

361C<8

362C<8

363

364

365

366

367

368

369

370

371

372

373

374

375

376

377

378

379

380

381

382

383

384

385

386

387

388

389

390

391

392

393

394

395

396

397

398

399

continued:

23)=281979\C(7,24)=61845\C(7,25)=-346731\C<7.26)=-42966 27)=-39672\C<7r28)=-30183\C(7.29)=-15678\C<7,30)=1878 31>=19734\C(7,32>=34353\C<7r33)=41412\C<7>34)=35802 35)=11628VC<7.36>= -37791\C<7•37>=- 116820

38>=-105864\C(7r39>=-74601\C<7>40>=-27846\C<7.41)=26376 42>=76830\C<7i43)=109071\C<7»44>=105444\C<7,4 5)=45084 46>=-96084\C(7,47)=-160740\C<7,48)=-141873 49)=-88749\C<7,50>=-11799\C<7,51)=71592\C<7.52)=137085 53>=153387\C(7i54)=82251\C(7i55)=-121524 56)=-137340\C(7/57)=-116577\C(7,58)=-59253 59>=19737\C(7.60)=9556B\C<7i61>=133485\C(7r62)=88803 63)=-93093\C(7r64)=-124740\C<7>65>=-99528 66>=-32043\C(7.67)=53262\C<7.68>=1156 32\C(7i69)=9 8010 70)=-72963\C(7»71)=-22230\C(7>72)=-15912\C(7,73)=l:17 74>=17082\C(7,75)=20358\C<7.76)=-10530\C(7r77>=~12210 78)=-6963\C(7,79)=4983\C(7,80) = 12 24 3\C(7,81)=--4158 82)=-630\C(7,83)=-171\C(7r84)=603\C(7,85)=-117 86>=-90\C(7.87)=48\C<7r88)=-3\C<8rl)=0\C<8r2>=77 3)=149\C(8r4>=211\C<8r5>=258\C(8,6>=285\C<8,7)=287 8)=259\C(8F9)=196\C(8rl0)=93\C<8rll)=-55\C(8,12)=-253 13)=-506\C(8,14)=0\C(B,15)=13\C(8rl6)=25\C(8.17)=35 18)=42\C(8rl9)=45\C(8.20)=43\C(8.21)=35\C(G.22)=20 23)=-3\C(8.24)=-35\C<8,25)=-77\C(8i26)=-0\C<8.27)=54 28)=103\C(8,29)=142\C(8,30)=166\C(8»31)=170\C(8r32)=149 33)=98\C<B.34)=12\C(8,35)=-114\C(8t36)=-285\C(8,37)=0 38)=44\C(8,39)=83\C(8r40)=112\C(8r41)=126\C(8r42)=120 43)=89\C<8.44)=28\C(8f45)=--68\C<8.46)=-204\C<8.47) = 0 48)=7\C(8.49) = 13\C(8,50) = 17\C<8»51) = 18\C(8,52)=-15 53)=7\C(8,54)=-7\C(8.55)=-28\C(8.56)=0\C(8,57)="27 58)=49\C<8.59)=61\C<8.60)=58\C<8.61)=35\C<8,62)=-13 63)=-91\C(8»64)=0\C(8,65)=4\C(8r66)=7\C(8,67)=8 68)=6\C(8i69)=0\C(8,70)=-ll\C(8r7 1)=0\C(8r72)=14 73)=23\C(8.74)=22\C(8r75)=6\C(8r76)=-30\C(8.77)=0 78)=9\C(8>79)=13\C(8,80)=7\C<8i81)=-14\C<8,82)=0 83)=1\C(8,84)=1\C(8>85)=-1\C<8.86>=0\C(B.87)=2 88)=-l RETURN

WEIGHTS SUBROUTINE N3=N0. OF DATA POINTS

TO BE AVERAGED OVER B(ItJ)=THE TABLE NUMBER THE TABLE IS STRUNG OUT STARTING WITH THE 25 POINT SET WHICH, AS IT IS IS SYMMETRICAL* IS REDUCED TO 13 ELEMENTS.

G0SUB 397

G0SUB 407

RETURN

RETURN

B(I B(I:

B(I

B(I:

J)=5 J>=3 J)=5 J) = 3

THEN THEN THEN THEN

REM

REM

REM

REM

REM

REM

REM

REM

REM

REM

IF

IF

IF

IF

L=12

K = l

FOR K1=0 TO L

U(K1)=C(B(I»J).K)

K = K + 1

NEXT Kl

REM TABLE IS READ IN

REM SEQUENCE UNTIL THE

REM RIGHT SET IS FOUND.

IF A=L THEN RETURN

L = L-1

GOTO 381

TABLE 12 (5) SUBROUTINE THIS TABLE IS FOR THE LINEAR LEAST SQUARES SMOOTHING AND IS ONLY A MOVING AVERAGE. K=0 TO 12

REM

REM

REM

REM

REM

FOR

U < K ) = 1

NEXT K

400 RETURN

401 REM ********************

402 REM TABLE 13 (3) SUBROUTINE

403 REM THIS TABLE IS FOR

404 REM LINEAR LEAST SQUARES

405 REM FIRST DERIVATIVE

406 REM SMOOTHING.

407 FOR K=0 TO 12

408 U<K)=-K

409 NEXT K

410 RETURN

411 REM ********************

412 REM DATA VECTOR SUB.

Listing 1 continued on page 274

272 March 1981 © BYTE Publications Inc

KEYS TO PRODUCTIVITY

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esc 1

If you plan, make, use, or buy computer systems or services, you can't afford to miss the upcoming National Computer Conference, McCormick Place, Chicago, May 4-7.

The theme of this year's conference is "Keys to Productivity", how to use computers and computer services to help increase output and control costs.

Come see the latest in new equipment and money-saving techniques at over 300 exhibits. Take your pick of over 100 technical sessions and 21 Professional Development Seminars. Enjoy the Personal Computing Festival, now a part of the main conference. _^

Save time. Save money. Pre-register now for the most dynamic NCC ever. You can:

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(800) 556-688S.

Circle 186 on inquiry card.

BYTE March 19B1 273

Circle 187 on inquiry card.

WORKING OVERTIME

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Payroll, Word Processing, Accounting &

Financial Management, Educational

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Check your Local Dealer or Contact:

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TELEVIDRO 912 $665

TELEVIDEO 920 715

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HAZELTINE 1500 850

PRINTERS

NEC 5510 $2540

NEC 5520 2900

NEC 5530 2520

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o

Listing 1 continued:

413 REM THE INPUT DATAr Y(K)r

414 REM ARE CONVERTED TO A

415 REM DATA VECTOR WHICH IS

416 REM AUGMENTED BY ZEROES ON

417 REM BOTH THE LEFT AND

418 REM RIGHT.

419 FOR K = 0 TO A

420 D(K)=0

421 IKK+N4+A+1>=0

422 NEXT K

423 FOR K = l TO N4

424 IKK + A) = Y(K)

425 NEXT K

426 RETUF.N

427 REM ********************

428 REM CONVOLUTION SUBROUTINE

429 REM THIS ROUTINE SMOOTHS THE

430 REM DATA POINT M USING THE

431 REM SURROUNDING N3 DATA POINTS.

432 REM THE WEIGHTING FUNCTION IS

433 REM U(I>, AND THE DATA IKK").

434 REM THE SYMMETRY IN WEIGHTING

435 REM IS GIVEN IN U.

436 REM THE RESULT IS D.

437 REM .THE RESULT IS NORMALIZED

438 REM USING V.

439 D=0

440 D="D + U(0)*D<M)

441 FOR K-=l TO A

442 D=H+U(K)*(U*D(M+K)+D(M-K))

443 NEXT K

444 D = D/V

445 RETURN

446 REM ********************

447 REM DATA SHIFT SUB.

448 REM THE SHIFTED AND

449 REM SMOOTHED DATA SET

450 REM IS IKK). THE DESIRED

451 REM SMOOTHED SET IS TICK).

452 FOR K==l TO N4

453 Y1(K)=-Y1(K + A)

454 NEXT K

455 RETURN

456 REM ********************

457 REM STANDARD DEVIATION

458 REM SUBROUTINE

459 D*0

460 FOR K=l TO N4

461 D=D+(Y(K)-Y1(K))*(Y(K)-Y1(K))

462 NEXT K

463 D = SQRT(D/(N4-I-.999999) )

464 REM IF YKK) IS A DERIVATIVE

465 REM THEN CALCULATION IS NOT

466 REM APPLICABLE.

467 IF N2>0 THEN D=0

468 RETURN

469 REM ********************

470 REM PLOTTING SUBROUTINE

471 REM SHIFT DATA TO NON-NEGATIVE

472 PRINT

473 PRINT 'INPUT DESIRED PLOT WIDTH. ",

474 INPUT L

475 REM FIND MAX. DATA VALUE

476 C=0

477 FOR K=l TO N4

478 IF C<D(K) THEN C=D(K)

479 NEXT K

480 REM DETERMINE PRINTING SCALE VALUE

481 A=L/C

482 PRINT

483 PRINT

484 PRINT"***** DATA PLOT (SCALED) ******

485 PRINT

486 PRINT

487 PRINT 'MAXIMUM VALUE= ",C

488 FRINT

489 PRINT

490 REM GO TO AXIS PRINT SUBROUTINE

491 GOSUB 519

492 FOR K=l TO N4

493 REM INSERT LINE FEED FOR AUTO SPACING

494 FOR P = l TO (I NT(0.6*L/N4) )

495 PRINT-t■tTAB(L),■!■

496 NEXT P

497 REM LOCATE DATUM POSITION

498 E2 = A*D(K) Listing 2 continued on page 276

274 March 1981 © BYTE Publications Inc

Circle 188 on inquiry card.

CP/M®«*IBM

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Evchangr data files with miisl IBM and DEC. equipment through REFORMATTER disk utilities. With REFORMATTER. you can read and write IBM .-(740 and DEC RT-'l 1 formatted diskettes on your CP/M system. Programs feature bi-directional data transfer and full directory manipulation. ASCII/EBCDIC conversion provided with CP/M--IBM.

Each program 5195.00 from stock. Specif)' CP/M*»IBM or CP/M**I)EC when ordering.

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CIVM* is a regtsttTcd trademark «if Digii;il Research.

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Circle 259 on inquiry card.

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Circle 261 on inquiry card.

REAL TIME

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■ Ideal for home, personal and business computer systems; surveillance monitors ■ 12" diagonal video monitor • Composite video input • Compatible with many computer systems • Solid-state circuitry for a stable G sharp pic lure • Video bandwidth —12 MHz ± 3 DB • Input inv pedance—75 Ohms • Resolution—650 lines Minimum IM Central 80% of CRT; 550 Lines Minimum beyond central80% ofCRTreFEIARS-375 • Dimensions—] 1.375'1 high; 16.250" wide; 11.250" deep (exclude video input connector) • Weight—6.5KG04.3 lbs) net

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Circle 263 on inquiry card.

Circle 264 on inquiry card.

Circle 265 on inquiry card.

Listing 1 continued:

499 REM FORMATTED PRINT

500 IF E2>=1 THEN GOTO 503

501 PRINT-*-,

502 GOTO 506

503 PRINT- ! - ,

504 PRINT TAEKE2) r "* -»

505 IF INT(E2)=L THEN GOTO 507

506 PRINT TAB(L>.-!-,

507 PRINT

508 NEXT K"

509 REM GO TO AXIS PRINT SUBROUTINE

510 GOSUB 519

511 PRINT

512 GOSUB 535

513 PRINT

514 PRINT

515 REM RETURN TO DATA SOURCE PROGRAM

516 RETURN

517 REM *###*###*

518 REM AXIS PLOT

519 FOR K=l TO L/5

520 PRINT'I ,

521 NEXT K

522 PRINT"I-f

523 E4=(K-1)*5+1

524 IF E4=L+1 THEN PRINT

525 IF E4=L+1 THEN GOTO 532

526 E4=E4+1

527 IF E4>=L+1 THEN GOTO 530 52B PRINT--"t

529 GOTO 526

530 PRINT-:"

531 REM RETURN TO MAIN PLOTTING PROGRAM

532 RETURN

534 REM PAUSE

535 PRINT "CONTINUE" ,

536 INPUT R4$

537 PRINT

538 RETURN READY

Text continued from page 264:

(eg: a government contract) so that, depending on the situation, the next year's sales might be either exactly the same or drastically different. Thus data smoothing must be performed using some common sense concerning how to evaluate the results.

The Moving Average

This section presents the basic table-oriented algorithm; the following section provides the mathematical derivation of the table values for the linear leastsquares case. Although the mathematics may appear complicated, especially for the parabolic, cubic, and higher fits, you will find the actual application of the results very simple.

The algorithm is conceptually identical to that of the moving average. In the calculation of the three-point moving average, the data point for the month of interest (using our example from table 1) is replaced by the average Value of that data point and its two surrounding neighbors:

S(t) =

Y(t-1) + Y(t) + Y(t + 1)

(2)

In this notation, S(t) is the smoothed value at position t and Y(t) is the actual datum for position f. If a five-point moving average were used, the corresponding equation would be:

S(t) = Y(t-2) + Y(t-l) + Y(t) + Y(t + l) + Y(t + 2)

TUT TXTTYP"R f^T Of^Tf "PT T 7Q™ PUT TIME AND REMOTE

iflUn l^CIV^l^^f^JV 1LUO CONTROL IN YOUR APPLE II

The THUNDERCLOCK PLUS is two peripheral systems on one card for your APPLE II OR II PLUS. An accurate, reliable, real-time clock/calendar and an interface for the popular BSR X-10 Home Control System.

The THUNDERCLOCK clock/calendar makes accurate time and date available to your programs: month, date, day-of-week, hour, minute, and second, in any of four software selectable formats. On-board batteries keep your THUNDERCLOCK running when your APPLE II is turned off - for up to four years before battery replacement. On-card IK firmware makes reading or setting the time easy from APPLESOFT or INTEGER BASIC, PASCAL, or assembly language programs. And it provides software selectable interrupts at any of three rates: 64, 256, or 2048 interrupts/second.

THE PLUS

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THUNDERCLOCK and your programs can send all 22 BSR X-10 commands so you can

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software package! The THUNDERW ARE SCHEDULER software lets you create schedules to

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includes: SCUTIL- the SCHEDULER utility that lets you make or change a schedule, and SCHED- executes your schedules in

real-time using the THUNDERCLOCK. SCHED runs in the 'background' soyoucanrun other programs in the 'foreground'.

The THUNDERCLOCK PLUS is a SYSTEM for your APPLE II. Supported by intelligent, easy to use firmware, a powerful software package, and good documentation!

Available through your dealer. r„T,K S"*BI"e,? "'?!!,prices!

6 7 THUNDERCLOCK PLUS $139

__, Clock/calendar card with batteries and If Vour dealer doesn't carry the

JSPI user's manual THUNDERCLOCK PLUS:

nsJWb'- -9.1s v ^,K,^-r-^r-.^^„^^,^K, «. ORDER TOLL FREE (VISA/MC) CALL:

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■\fflP. ± X'10 i"^rface, and user's guide THUNDERW ARE INCORPORATED

bsr x-io i. a trademark of bsr (USA) ltd. MANUALS ONLY, each $5 P.O. Box 13322, Oakland, CA 94661

APPLE II is a trademark of APPLE COMPUTER, INC California residents add 6% sales tax

276 March 1981 © BYTE Publications Inc

Circle 189 on inquiry card.

"> - ■ J,v

Fine Software Tools in C

The Toolbox

£*•

list

prints that missing source listing

xref

cross reference C programs

sort

alphabetize by all or part of text

me

col

arrange text in columns on page

■;

print

paginates text for hard copy.

■

and

more

All programs are in portable Whitesmith C xref and list are compatible with the compiler's error listing Title lines on list and print output includes the date on RT-11 systems Source code on 8" floppy and manual available immediately for $45 [tax and shipping included] Specify RT-11 or CP/M format

The Toolsmith

Dept. BYTE

P. O. Box 22511

San Francisco, CA 94122

RT-11 is a trademark of Digital Equipment Corp CP/M is a trademark of Digital Research.

Circle 266 on inquiry card.

MEMORY $10

$5 $14

CMOS RAMS I ~

ALL PRIME QUALITY CHIPS

ORDERING INFORMATION

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Circle 268 on inquiry card.

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Circle 270 o n inquiry card.

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Calif. Residents add 6% Sales Tax Circle 269 on inquiry card.

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Circle 271 on inquiry card.

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?? APPLE*-ITIS ??

Hardware Or Software Problems?

Save time and money by having your own diagnostic disk. Deter mine immediately if you have a hardware problem.

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16 BIT PROCESSING ACOM'S P188

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4151 Middlefield

Palo Alto, CA 94303

(415) 494-7499

Circle 272 on inquiry card.

1978

Th

ree-Point

Five-Point

Month

Sales Volume

Smoothing

Smoothing

(November)

(1235)

(December)

(2408)

January

3279

2703

2842

February

2421

3521

3321

March

4864

3638

3475

April

3629

3891

3768

May

3180

3851

4520

June

4744

4702

4277

July

6181

4859

4235

August

3653

4417

3944

September

3418

2931

3242

October

1722

2125

2487

November

1235

1788

2412

December

2408

2307

2213

(January)

(3279)

(February)

(2421)

Standard Deviation:

719

994

Table 2: 1978 sales with three-poi

nt and five

-point moving

average data

smoothing.

Note tha

extrapolat

ed figures must

be given for

November and D

ecember 1977 and January and

February 1979 in order

for

the

smoothed

versions to be

calculated.

6000

RAW

DATA

5000 1000 3000

■''SV

1>&J

5 POINT AVERAGE—' a = 994

\ /-THREE POINT AVERAGE ~"\i cr = 719

2000

V~^

— —' /

1000

1 1

i

1 1

1 1

JFMAMJ JASOND

MONTH IN 1978

Figure 2: Computation of a smoothed set of data using the moving-average method. The chart shows the raw data (solid line), the smoothed version using a three-point average (the dashed line) and the smoothed version using a five-point average (the dotted line). The Greek letter a indicates the standard deviations for the respective graphs.

Note that the number of points included in the average is odd. This is required to keep the smoothed points from being shifted in phase. Contrast this with the average of the two data points for June and July—the smoothed value would have to be plotted halfway between the two months.

The results of applying the three-point and five-point moving averages to the data shown in table 1 are given in table 2, and the results are plotted in figure 2. The assumption that the pattern will repeat is used to supply the extra data points required at either end of the data set.

This particular example demonstrates several general features of moving-average data smoothing. First, from figure 2, it is apparent that the moving average tends to smooth out extreme fluctuations in the data. Using a fivepoint average instead of a three-point one has a greater effect on limiting the range of variation. However, using a five-point average does not guarantee that a locally smoother curve will result, although the tendency will exist.

Note, for example, the region near May. The five-point average equally weights the values from the two-month periods on either side, which, in this case, contain two peaks (one in March and one in July). Thus, where there is a local minimum in the raw data, the five-point average gives a local maximum. This obvious weakness in the smoothing is due to the implied assumption that the five data points over which the averaging is performed should all be equally weighted; the July value is included with the May value with equal importance, even though the smoothed result is being calculated for May. As we will see later, nonuniform weighting may be used, partially avoiding this problem.

The second feature to note is that the three-point and five-point moving averages naturally give different results. For the smoothed July value, the three-point method gives an average of 4859, with a standard deviation of 719, while the five-point method gives an average of 4235, with a standard deviation of 994.

Which result is correct? The answer is probably neither. However, one result is likely to be more representative of the truth than the other. If reason exists for believing that correlation between monthly results extends only as far as one month on either side of a given month, then the three-month average is likely to be better. (That is, if the sales for the June and August time periods are expected to be the same as those for July, with the only difference being the "noise," then it is reasonable to average these three months, or maybe more. This is the case for, say, a five-month average. However, if the May and September sales are expected to represent a seasonal response different from the response that caused the July sales, then the average should be limited to a span of only three points. Such might be the case if the data in table 1 represented the sales of a seasonal item such as lawn mowers.

The conclusion is that the number of points used in the moving average (3, 5, 7, 9,...) should be dictated by some knowledge of the time frame associated with the underlying customer sales motivation (or, for physicists, the physics; for engineers, the forcing function). The span parameter in the moving-average and the weightedaveraging techniques to be discussed in the next section should generally be chosen based on some idea of the general trends that are the basis of the observed data. With this in mind, the moving-average calculation can then be used to refine the estimate in an intelligent manner. Only in this way can real information be derived from the data.

Least-Squares Data Smoothing

The simple moving-average calculation presented in the previous section is a special case of the general concept of weighted averages, which can be stated mathematically as follows:

S(t)= £ w(i)Y(t+i)/ E w(i)

w(-n)Y(t-n) + ...+w(0)Y(t) + ...+w(n)Y(t + n)

(4)

E w(i)

For the moving-average case we have w(i) = 1 for all i.

278

March 1981 © BYTE Publications Inc

Circle 190 on inquiry card.

Circle 191 on inquiry card.

IEEE-488 To TRS-80* INTERFACE

I

t sciEHTinc mmm munma«

MODEL *aB-80(

Everything needed to add powerful GPIB-488

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11 NEIL DRIVE • OLD BETHPAGE. NEW YORK 11804 TELEPHONE (516) 694-3205

'Trade Mark ol Tandy Corp. There is no affiliation between Scientific Engineering Laboratories and Tandy Corporation or Radio Stiack

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BYTE March 1981

279

Num

ber of Averaging Points

Index/ 25 23 21 19 17 15 13 11 9 7 5 3

12 1

11 1

10 1

9 1

1 1

1

8 1

1 1 1

1

7 1

1111

N

T

6 1 5 1

11111 111111

E G

4 1

3 1

1111111 11111111

E R

2 1

1 1

111111111 1111111111

W

0 1

-1 1

1111111111 1111111111

E

-2 1

111111111

1

-3 1

11111111

G

H

-4 1 -5 1

1111111 1111111

T

-6 1

111111

S

-7 1

11111

-8 1

1111

W(i)

-9 1 -10 1 -11 1 - 12 1

Normalizing factor,

1 1 1

N 25 2

3 21 19 17 15 13 11 9 7 5 3

Table 3: Weighting

coefficient table for the moving-average

method of data smo

othing. This is a trivial case, but it clearly

introduces the table

concept.

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At this point, you should become familiar with the idea of tables of weighting coefficients, which are the w(i) terms in equation 4. Such a tabulation for moving averages is shown in table 3. Although this table is trivial, it demonstrates the concept of integer weighting coefficients as presented in an article by Savitzky and Golay. (See references.) In that article (and here as well), the weighting coefficients, w(i), are integers, and the normalization N is performed after the multiplication/addition sequence:

S(t) =

1_ N

£ w(i)Y(t+i)

(5)

For a given number of averaging points, the coefficients are easily found in the table, the summation performed, and the result then normalized (by dividing by, for the moving-average case, N = 2« + l, the sum of all the w(i)s from w(— n) to w(n)).

For the moving average, it is very obvious how the entries in table 3 were obtained. As an illustrative example, we will now derive the table entries for a linear (as opposed to parabolic, cubic, etc) least-squares smoothing.

Consider a set of data where there are 2n+l elements having coordinates (X, , Y,). Generally, the method of linear least-squares fitting leads to a "best fit" line having the equation:

Y(X) = mX + b

(6)

The "best fit" criterion is to find values for m and b such that the sum of squares, SS, is a minimum:

SS= £ (Y(X-)-Y,-)2

(7)

The case we are considering is a little special in the sense that we are examining least-squares fitting with only an odd number of data points. The index range is not the usual i = l to some positive value, but rather i=— n to i = n.

The analytical solution to the desired parameters, m and b, may be found in any standard statistics text. For example, reference 2 presents the results in a particularly convenient form modified here:

m- E (X- X)(Y- YV2 (X- X)' b=Y-mY

(8) (9)

In this notation, X and Y are simply the averages of X, and Y, :

X = £ Xi/ln+l

V = E Y./2W+1

(10)

(11)

The weighting coefficients we are looking for are implicitly contained in the above equations. This may be seen as follows.

We are interested in replacing the data point Y0 with a "better" one as determined by the least-squares smoothing. This smoothed value is simply:

Y = mX0 + b = mX0 + Y -m X

(12)

280

March 1981 © BYTE Publications Inc

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BYTE March 1981 281

Number o

Averaging Points

Index /

25

23

21

19

17

15

13

11

9

7

5 3

12

12

11

11

11

10

10

10

10

9

9

9

9

9

1

8

8

8

8

8

8

N

7

7

7

7

7

7

7

T

6

6

6

6

6

6

6

6

E

5

5

5

5

5

5

5

5

5

G

4

4

4

4

4

4

4

4

4

4

F

3

3

3

3

3

3

3

3

3

3

3

R

?

2

2

2

2

2

2

2

2

2

2

2

1

1

1

1

1

1

1

1

1

1

1

1 1

W

0

0

0

0

0

0

0

0

0

0

0

0 0

E

-1

-1

-1

-1

-1

-1

- 1

- 1

- 1

-1

-1

-1-1

1

-2

-2

-2

-2

-2

-2

-2

-2

-2

-2

-2

-2

G

-3

-3

-3

-3

-3

-3

-3

-3

-3

-3

-3

H

-4

-4

-4

-4

-4

-4

-4

-4

-4

-4

T

-5

-5

-5

-5

-5

-5

-5

-5

-5

S

-6

-6

-6

-6

-6

-6

-6

-6

-7

-7

-7

-7

-7

-7

-7

-8

-8

-8

-8

-8

-8

-9

-9

-9

-9

-9

-10

- 10

-10

-10

-11

-11

-11

-12

-12

Normalizing

factor,

N

1300

1012

//O

b/0

408

280

182

110

6U

28

10 2

Table 4:

Weig h ting-co efficient

table for linear,

easf

squares, first

derivative data

smoo

thing

. The symmetry arour

rf i =

-0 allows this

table to

be cut

in half when used ir

a computer program.

f RUN J

DIMENSION ARRAYS

INPUT

NO. OF ELEMENTS IN SET AVERAGING RANGE LEVEL TO FIT DERIVATIVE ORDER

DETERMINE TABLE TO BE USED

CHECK FOR INPUT ERRORS

YES /frror\

Since the data points are equally spaced, it does no harm to redefine the X, values. In _p_articular, choose Xi = i. In that case, Xo = 0 and X = 0, giving the smoothed value:

Y= Y = £ Y,/2n+l =

2n + l

EX

(13)

That is, the smoothed value obtained by the linear leastsquares criterion is just the moving average! Thus table 3 gives the weighting coefficients for linear, least-squares data smoothing.

The analysis can be taken yet one more step. If we want the first derivative at Xo = 0 of the function fitted to the 2n + l points centered at X0l we have simply:

INPUT DATA SET

PLOT DATA

SMOOTH DATA SET

DISPLAY SMOOTHED DATA SET

STANDARD DEVIATION (IF APPLICABLE)

PLOT SMOOTHED DATA

f END J

TABLE SUBROUTINE

ERROR CODE SUBROUTINE

PLOTTING SUBROUTINE

SUPERVISOR SUBROUTINE

PLOTTING SUBROUTINE

dY dX

(14)

X = X0

Recalling that X =0 and noting that EX, Y is proportional to X Y , we get:

dY dX

X = X0

L X,V L X*,

(15)

Thus, the nonnormalized integer weighting coefficients for linear, least-squares, first-derivative data smoothing are:

W(i) =

with

(— n < i < n)

n(n + l)(2n + l)

N= £ «2 =

(16) (17)

The last two equations were used to generate table 4.

Two important characteristic features are apparent from table 4. The first is that the normalizing factor, N, is

Figure 3: Flowchart for the least-squares data-smoothing program given in listing 1. See figure 4 for the supervisor subroutine flowchart.

not simply a sum of the weighting factors in the corresponding column. That is true only for the moving average. Second, the table is symmetrical about the i = 0 row. The weighting tables are exactly symmetrical or inversely symmetrical, thus making nearly half the entries redundant. This property may be used to save program space.

Implementing the Algorithm

The algorithm represented by equation (5) may easily be implemented as a computer program that applies the appropriate table depending on the prompted inputs. The flowchart for such a program is shown in figure 3.

The program is laid out in modular (ie: subroutine) form. As shown in figure 3, the basic program flow is to input the smoothing parameters, check for errors in those parameters, and then input the data. The input data is

282

March 1981 © BYTE Publications Inc

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BYTE March 1981

283

then plotted, and control is subsequently passed to a generalized supervisor (or executive) program that performs the desired smoothing by calling in several other subroutines. (See figure 4.) The smoothed results are returned to the main program and are printed out along with the standard deviation between the original and smoothed data. In the case of derivative smoothing, which will be discussed later, the concept of standard deviation is not applicable, and 0 is printed. After the numerical display, the smoothed results are plotted.

The plotting routine properly deals with only nonnegative data. This restriction helps keep the program short and simple. If negative values are encountered, only the absolute values are plotted. This generally does not cause much confusion because the values themselves are also printed. The plot is only a convenience item.

The supervisor subroutine is interesting because it can be called by some other data-gathering program instead of the one outlined in figure 3. It requires the variables given in table 5a as input and returns the values given in table 5b.

Before entering the supervisor, the arrays must have already been dimensioned. The reason for this requirement is that in many BASIC interpreters an array cannot be dimensioned more than once. Since the supervisor subroutine may be called more than once, it therefore cannot contain DIM (dimension) statements.

The complete program is shown in listing 1. As can be seen from the listing, the subroutines indicated in figures 3 and 4 are clearly identified by liberal use of REM (remark) statements.

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(5a)

(5b)

N1: The level of fit (0,1,2,3,4,5).

N2: The order of the derivative (0,1,2,3).

N3: The number of points to be smoothed over

(3,5,7,9,...25). N4: The number of data points. Y(K): The data array.

E: The error code if an improper input was given. Y1(K): The smoothed data (or derivative). D: The standard deviation (if applicable).

Table 5: Variables used in the supervisor subroutine that appears in the flowchart in figure 4. This subroutine is given in lines 98 thru 158 of listing 1.

(main N PROGRAM )

INITIALIZE THE OUTPUT VECTOR,Yl(K)

DETERMINE TABLE TO BE USED

CHECK FOR ERRORS

f RETURN \>

OBTAIN COEFFICIENTS

U = SYMMETRY VALUE V= NORMALIZATION

GET WEIGHTING COEFFICIENTS

CREATE AUGMENTED DATA VECTOR, D (K)

SMOOTH D(K)

EXTRACT Y1(K) FROM D(K)

OBTAIN STANDARD DEVIATION

f RETURN )

TABLE SUBROUTINE

ERROR CODE SUBROUTINE

COEFFICIENT SUBROUTINE

WEIGHTS SUBROUTINE

DATA VECTOR SUBROUTINE

CONVOLUTION SUBROUTINE

SHIFTING SUBROUTINE

STANDARD DEVIATION SUBROUTINE

Figure 4: Flowchart for the supervisor subroutine. The supervisor calls several other subroutines in order to perform the task of data smoothing. Note that the calling program, shown in figure 3, can be entirely replaced by a program that obtains the appropriate inputs and then calls this subroutine.

284 March 1981 © BYTE Publications Inc

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A

M

B(I,J)

N1

C(I.J)

N2

D

N3

D(l)

N4

E

O

E(D

P

E2

R4$

E4

U

I

U(l)

J

V

K

V(I.J)

K1

W(l)

L

Y(l)

Y1(l)

Table 6: A table of variables used

in the subroutines of listing

1. This table is used to prevent du

plication of variable names

when generating a new main

program that uses the

subroutines of listing 1.

Derivative

0 1

2

3

1

Yes Yes

No

No

Level 2

Yes Yes

Yes

No

of 3

Yes Yes

Yes

Yes

Fit 4

Yes Yes

Yes

Yes

5

Yes No

Yes

No

Table 7: Table of perm

itted data-smoothing operations with

the program shown in

listing 1. The derivative/level-of-fit

combinations omitted

were done to

'<eep the

program at a

reasonable length.

The smoothing parameters are stored as explicit arrays. It would have been more efficient to store this information in BASIC data statements. However, the supervisor (and the routines it calls) is meant to be a subroutine, and it is not good programming to use data statements in subroutines that may be called often. For example, if the main program and the subroutine both have data stored that way, how does the subroutine read the appropriate data and restore the data pointer to its proper location after repeated calls? The way the program shown in listing 1 is written, the main program (statements 1 thru 96) can be replaced by a user program without any change in the subroutines. If you want to replace the main program, keep in mind that the subroutines have variables that should not also be employed in the calling program without some caution. The subroutine variables list is shown in table 6.

Using the Program

As presented, the program may be used to smooth data over the range of fits and derivatives shown in table 7. As an example of how the program operates, we will now apply it to the sales-volume example discussed earlier.

Listing 2 shows a sample run in which a parabolic (ie: second level) fit was applied using a five-point average. Note that sixteen data points are necessary to do this, since we require an additional two points on either side of the point of interest. (These points can be deleted later.) The user inputs are underlined. If a "fatal" error in the parameter input sequence had been made, the error

Text continued on page 290

286

March 1981 © BYTE Publications Inc

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Listing 2: Sample run of data smoothing program, using data from table 1. In this listing, user input is underlined.

RUN

DATA SMOOTHER FOR EC1UALLY SPACED DATA SETS

INPUT THE NUMBER OF DATA POINTS IN SET: 716

HOU MANY POINTS ARE

TO DE AVERAGED OVER! ?J

WHAT IS THE DESIRED LEVEL OF FIT (1,2.3.4.5): 72

UHAT IS THE DESIRED DERIVATIVE (0,1.2.3): TO

INPUT DATA AS PROMPTED!

1

71235

n

72408

3

73279

4

7 2 4 21

5

74864

6

73629

7

73180

8

74744

9

76181

10

73653

11

73418

12

71722

13

71235

14

72408

15

73279

16

72421

INPUT DESIRED PLOT UIDTH! 750

***** DATA PLOT (SCALED) *****

MAXIMUM VALUE=

CALCULATING,

THE SMOOTHED DATA IS!

CONTINUE?^

288 March 1981 © BYTE Publications Inc

1

1144

4

2

2509

7429

3

2725

5429

4

3450

3429

5

3883

1714

6

3906

4571

7

3468

6

8

4889

54 2 9

9

5 315

6286

10

451 1

1714

11

2867

3714

12

1912

D

13

14 41

8286

14

2362

1429

15

314 2

,4571

16

2093

,7429

C0NTINUE7Y

THE STANDARD DEVIATION BETWEEN THE SMOOTHED AND UNSMOOTHED DATA SETS IS 589.8642

C0NTINUE7Y

INPUT DESIRED PLOT UIDTH! 750

***** DATA PLOT (SCALED) *****

MAXIMUM VALUED 5315.6286

CONTINUE?

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Error

Code Explanation

0 No Error.

1 Number of data points to be averaged over is too

small.

2 Number of data points to be averaged over is too

large.

3 The order of the derivative is greater than the level

of the fit, which gives a trivial (0) result.

4 The level of fit attempted is too high.

5 The order of the derivative attempted is too high.

6 The particular table required is not available in the

program.

7 There is not enough data to do the smoothing re

quested.

8 An illegal or otherwise out-of-range parameter was

given.

Table 8: Table of error codes returned by a call to the supervisor subroutine.

6000

5000

'"N.

4000

. v/

\

3000

- yT

\

2000

N. /

1000

i i i i i i

A M J J A

MONTH IN 1978

Figure 5: Chart of smoothed sample data using five-point parabolic smoothing. This chart is identical to the one plotted in listing 2.

Text continued from page 286:

would have been indicated according to the code in table 8.

As shown in listing 2, the program prompts for all the inputs. The user can then specify the plotting width for the terminal being used. Note that only absolute values are plotted. The program then performs the smoothing and calculates the standard deviation (when applicable).

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Finally, the routine plots the smoothed data.

The smoothed data for the sales-volume example has been replotted as shown in figure 5. Observe that the first two and last two of the sixteen input values have been discarded. If a seven-point average had been used, three points on either side of the desired results would have been dropped. Comparing figure 5 with figure 2, we see that the five-point parabolic smoothing looks much more "reasonable" than the three-point and five-point linear smoothing. The peak in July is apparent, as well as the dips in May and November. Recalling that the nominal purpose of the example was to better predict the July sales volume, we find the value to be 5316 units, with a standard deviation of 590. We expect that the standard deviation will be lower for the parabolic fit than for the corresponding linear fit, and it is.

Discarding points at the ends of the smoothed data set is necessary. The smoothing at each position uses data on either side. At the extremes of the data set there is missing information. The program supplies values (eg: 0) for this missing data. In general, if the number of data points averaged over is N3, then the number of data points that should be discarded at either end of the data list is (N3-l)/2.

MFJ

Square-Wave Example

We will now look at the results of smoothing a very discontinuous function, the square wave. The purpose is to show the comparative effects of the various levels of fit on "smoothing" an abrupt transition.

290 March 1981 © BYTE Publications Inc

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BYTE March 1981

291

Using a computer, the mechanics of

data smoothing can be made fairly

simple.

To electrical engineers, the multipoint averaging technique presented in this discussion is the equivalent of nonrecursive digital filtering. The way in which the calculation is applied is identical to convolution. According to one of the important theorems of Fourier transform theory, performing a discrete convolution on a "signal" (the data) is the same as frequency filtering. The shape of the frequency filter is simply the discrete Fourier transform of the weighting function.

Thus, every table of weighting coefficients can be converted to a corresponding set of filter coefficients. Usually, in electrical engineering one chooses the frequency filter response and then finds the convolution (ie: weighting) coefficients. In our case, we chose our coefficients according to a least-squares curve-fitting criterion first. However, the idea of frequency filtering is still valid.

The square wave is built of many spatial-frequency components. Filtering out some of the high-frequency components results in a less-than-abrupt square-wave transition. Figure 6a on page 294 shows the square-wave input data that was provided as an example to the program. The square wave is 1 unit high and 18 units wide. For clarity, lines have been drawn between the points plotted by the computer.

Figure 6b shows the effect of applying a linear (first level fit, zeroeth-order derivative) smoothing using nine averaging points. The effect is simple. Applying a parabolic fit leads to a more curious form. (See figure 6c.) The dashed parts of the "curve" indicate negative values. The overshoot effect is called ringing.

Going one step further and applying a quartic (fourthorder polynomial) smoothing, we get figure 6d. Note that the ringing has increased, but the standard deviation between the square wave and the quartic smooth version has decreased relative to the parabolic or linear case. There is more ringing but a better fit. The overshoot effect is related to the Gibbs phenomenon, which is a nonuniform convergence problem in Fourier transform theory.

The square wave may also be used to demonstrate derivative smoothing. (See figures 7a and 7b on page 298.) It might be argued that these curves are not very smooth: however, remember that the unsmoothed derivative is an infinite spike!

Figure 7a calls attention to an important point regarding derivatives. From figure 6b, we might have expected the linear smoothing of the first derivative to be just a step from 0 to 1/9 and back to 0 again, since the linearly smoothed function has a constant slope ramp on one side. However, the result shown in figure 7a resembles a parabola. The reason for the difference is that the derivative is not derived from the smoothed data. Rather, at each data point the derivative of the curve fitted over the nine-point interval surrounding that position is used. This is not the same as the slope between neighboring smoothed data points, a very important conceptual difference.

As you might expect, the situation for the second and third derivatives is even more complicated. Examination of those forms is left to you.

Conclusion

As indicated earlier, the mechanics of data smoothing can be made fairly simple given a computer that can execute the program provided. Running the program is easy. Choosing the appropriate fitting parameters and applying the results is much more difficult. The two main choices for fitting are the averaging range and the level of fit. The averaging range should be chosen based on an idea of the true correlation between the data points. If changes over a range of N3 are not expected, then an averaging range of that size is warranted.

Choosing the level of fit is more difficult. In the salesvolume example, the parabolic fit appeared better than the corresponding linear fit. However, that is a subjective judgment based largely on the feeling that the peak and two major dips observed in the data should appear in the smoothed curve. There is still no replacement for common senselH

REFERENCES

Savitzky A, and M JE Golay. "Smoothing and Differentiation of

Data by Simplified Least Squares Procedures." Analytical

Chemistry, Volume 36, Number 8, July 1964.

Wesolowsky, G 0. Multiple Regression and Analysis of Variance.

New York: Wiley Interscience, 1976.

Weast, R C and S M Selby. Handbook of Tables for Mathematics.

Third Edition. Cleveland OH: Chemical Rubber Company, 1967.

292 March 1981 © BYTE Publications Inc

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Prices f.o.b. L.A. Minimum freight & handling charge -S4.95. In CA. add 6% sales tan. Goods subject to availability. We'll beat any advertised price if competitor has goods on ha CallMon-Sat7AM-6PM. V/SA- Outside CA, toll free 800-421-8045

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MAIL ORDER DISCOUNTS

[apple computer

Sales and Service

APPLE II PLUS 48K

$1,175

APPLE /## CALL FOR PRICES

ACCESSORIES

DISK II DRIVE & CONTROLLER (DOS 3.3) 525

DISK II DRIVE ONLY 445

INTEGERBASIC FIRMWARE CARD 149

APPLESOFT II FIRMWARE CARD 149

M&RSUPRMODRF MODULATOR 30

CENTRONICS PRINTER INTERFACE CARD . .179

HIGHSPEED SERIAL INTERFACE CARD 139

SSM AIO SERIAL/PARALLEL I/O CARD .■ 169

MICROSOFT Z-80 SOFTCARD SYSTEM ... 290 VIDEX 80 COLUMN BOARD

W/GfiAPHICS AND SWITCH 350

HAYES MICROMODEM II 325

SILENTYPE PRINTER W/INT. CARD 535

LANGUAGE SYSTEM W/PASCAL 395

GRAPHICS TABLET 649

LEEDEX 12" B&W MONITOR & CABLE 149

SOFTWARE

APPLE DOSTOOLKIT 65

APPLEPLOT GRAPH & PLOT SYSTEM 60

VISICALC 115

DESKTOP PLAN 79

CCADATA MANAGEMENT B5

THECONTROLLER BUSINESS SYSTEM

APPLE FORTRAN

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BASF 5''t " DISKETTE (10)

VINYL DISKETTE HOLDER PAGE (10).

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TO ORDER: Please phone using VISA, Master Card and American Express. Or send cashier's check, money order or personal check (allow 10 business days to clear). VISA and MC credit card service add 2%. AE credit card service add 5%. Shipping, handling and insurance in U.S. add 3% (minimum $3). California residents add 6% sales tax. Foreign orders add 10% for shipping. Equipment is subject to price change and availability. All equipment carries factory warranty.

computer age. inc.

Authorized Apple Dealer & Service Center 4688 CONVOY ST., SUITE 105, SAN DIEGO, CA 92111 (714) 565-4062

Combine accurate flight characteristics with the best in animation graphics and you'll have SubLOGIC's

A2-FS1 Flight Simulator

for the Apple 11

on cassette or disk!

SubLOGIC's A2-FS1 is the smooth, realistic simulator that gives you a real-time, 3-D, out-of-the-cockpit view of flight. Thanks to fast animation and accurate representation of flight, the non-pilot can now learn basic flight control, including take-offs and landingsl And experienced pilots will recognize how thoroughly they can explore the aircraft's characteristics. Once you've acquired flight proficiency, you can engage in the exciting British Ace 3-D Aerial Battle Game included in the package. Destroy the enemy's fuel depot while evading enemy fighters.

Computer and aviation experts call the A2-FS1 a marvel of modern technology. You'll simply call it fantastic!

Special Features:

• 3 frame-per-second flicker free animation

• Keyboard or joystick input

$

25°°

on cassette, usable on all systems (16Kmemory required)

$

33°

on disk, usable on DOS 3.2, DOS 3.3, or Language System [32K memory required)

See your dealer or order direct. For direct order, include 51.25 and specify UPS or first class mail. Illinois residents add 5% sales tax. Visa and Mastercard accepted.

Present cassette users may send back their cassette (but nor the manual), along with S10 (first class shipping included), and receive the disk version.

LOGIC

Communications Corp. BoxV, Savoy, IL61874 (217)359-8482 Telex: 206995

Circle 218 on inquiry card.

BYTE March 1981

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Figure 6: Smoothing a square wave. The test square wave in figure 6a was smoothed in figures 6b thru 6d using a nine-point average. Figure 6b shows a linear smoothing. Figure 6c shows the results of a parabolic smoothing with a cubic smoothing giving the same results. Figure 6d shows the results of a quartic and quintic smoothing. In all figures, dashed lines denote negative values plotted here as positive. These figures and those of figure 7 were generated using the program given in listing 1.

294 March 1981 © BYTE Publications Inc

Circle 219 on Inquiry card.

Why buy used or obsolete boards, when you can purchase new IEEE standard current designs at

Spectacular Savings!

ALL GODBOUT ELECTRONICS FACTORY ASSEMBLED & TESTED BOARDS

20

%

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We carry the largest variety of S-100 products in the world. For a special cash price please call.

For our 1981 Catalog, please write

Subject to available quantities. Shipping and insurance extra. VISA and Master Charge accepted at no additional charge for orders over $500.00.

S-IDD,inc.

7 White Place

Clark, N.J. 07066

201-382-1318

Hours: Mon.-Fri. 10 a.m. to 6 p.m.

Circle 220 on Inquiry card.

THE FORTH SOURCE

Specializing in printed material for the FORTH language. Send for listing of current material.

Installation Manual $10.00

8080 Listing $10.00

6502 Listing $10.00

6800 Listing $10.00

6809 Listing $10.00

PDP-11 Listing $10.00 more

Using FORTH, Manual $25.00 PDP-11 User's Guide $20.00 Kitt Peak Primer $25.00

more

Dealer Inquiries Invited.

Write for complete listing of FORTH material.

MOUNTAIN VIEW PRESS

PO Box 4656

Mt. View, CA 94040

'■T^^ Anti-Static a ^"^\

Dust Cowers

Protect your computer and accessories.

• Anti-static vinyl helps prevent static from damaging sensitive components and causing faulty operation.

• Double-fold stitching will not rip out and is unmatched for strength and long life.

• Heavy gauge textured vinyl blends with any decor and folds easily for «^^S convenient storage. J

• Over 1000 custom designs gua- J ranteed to fit precisely.

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Yes, there are differences in Dust Covers. Differences which can be vitally important to the proper functioning of your system.

At Cover Craft we've manufactured the highest quality Dust Covers for the electronics industry for more than six years. We've been selected by major equipment manufacturers to make covers for their products. Our covers are in use in every state and in more than 50 countries. We know what it takes!

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c

COVER CRAFT

P.O. BOX 555 • AMHERST, NH 03031 •(603)889-6811

Circle 221 on inquiry card.

BYTE March 1981

295

(6c)

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(6d)

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296 March 1981 © BYTE Publications Inc

Circle 222 on Inquiry card.

Circle 223 on inquiry card.

DISCOUNT PRICES

APPLE II COMPUTERS

16K APPLE II

1089.00

32K APPLE II

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159.00

INTEGER CARD

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525.00

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-»-■«■■»--»- ATTENTION -h--h--h--h

* CENTRONICS 737 *

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-H--H--H--H--H- OWNERS -H--H--H--H--H

Cognitive Systems is proud to announce Justex 3.1 — a sophisticated printer driver designed exclusively for the Centronics model 737 dot matrix printer. Justex 3.1 is a highly optimized Z-80 machine language program occupying only 2k of memory. When combined with existing word processors, it allows full utilization of the 737's many features. These are some of the many features available with this program!

1/2

0) 1, 1 , or 2 spaces between lines like a typewriter

1) Optional right and left justification

2) Adjustable spacing between words

3) Use of the 737's N x 9 seriph character set

4) Sophisticated underline feature

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6) Normal and elongated text on the same page

7) Special columner mode, which allows adjustment of spacing between columns without changing the text

8) Optional line numbering for legal work

9) Full control over print wheel allows two column 'newsletter-style' text to be easily printed

Justex 3.1 is currently available in ready to run form far TRS-80 Mod. I Disk systems using Scripsit for $24,95 with the instruction manual selling for $9.95. Users with other Z-80/ 8080 based computers can purchase the commented source code for $19.95. CP/M users or TRS-80 owners using other word processors are asked to write for more information. This ad was printed using Justex. Readers are invited to circle the reader service # or write directly for more samples.

send check or money order to ... COGNITIVE SYSTEMS 350 Mira Loma Lane Escondido, CA 92025

(Dealer inquiries also welcome.)

D

* TRS-80 & Scripsit TM Tandy Corp. — CP/M TM Digital Research All orders + $2.50 postage/handling - CA residents add & *

Tips For Your Chips

Get the maximum use and enjoyment from your micro with these popular paperbacks

DATA FILE PROGRAMMING IN BASIC

LeRoy Finkel & Jerald R. Brown

With your own microcomputer, minimal knowledge of BASIC, and this easy-to-use guide, you can learn how to use data files to keep track of billings, customer inventory, and expenses, maintain mailing lists, process numerical and statistical information, and much more. Sample programs and lots of practical advice assist you every step of the way. The guide uses the most popular variants of BASIC, TRS-80 BASIC and Microsoft BASIC-80. An extensive appendix covers BASIC for the Northstar computer.

0 471 08333-X March 1981 approx. 320 pp. $9.95 (tent.)

Look lor these and other STGs at your favorite bookstore or computer shop. For

more information, and a complete listing of current and forthcoming STGs, write to Pam Byers, Dept. 7497.

Files, fun, and fancy functions plus practical applications

MORE TRS-80 BASIC™

Don Inman, Ramon Zamora & Bob Albrecht

This exciting new interactive guide to programming in TRS-80 Level II BASIC teaches scores of practical applications— both recreational and educational. You'll get a clear demonstration of different methods to display graphics; files handling techniquesapplied to both cassette and disk files; plus animation, games, and fun. 0 47108010-1 April 1981 approx. 300 pp. $8.95 (tent.)

Gef maximum power from your micro by using assembly language

INTRODUCTION TO 8080/8085

ASSEMBLY LANGUAGE

PROGRAMMING

Judi Fernandez & Ruth Ashley

Use your microcomputer to write fast, sophisticated, complex programs with the help of this guide, the only self-instructional book of its kind. You'll learn what machine language is, how to perform routine operations, input/output, conditional commands, machine language logic, stack routines, and more. Sample programs illustrate every technique and concept.

0 47108009-8 April 1981 approx. 300 pp. $8.95

Wiley Self-Teaching Guides also teach BASIC, COBOL, FORTRAN, Job Control Language, Flowcharting, and other computer skills.

How to perform complex, sophisticated operations with your micro

8080/Z80 ASSEMBLY LANGUAGE Techniques For Improved Programming

Alan R. Miller

Now advanced and intermediate programmers can get the most response their micro is capable of generating with the help of this complete guide to programming the 8080 and Z80 microprocessors. Learn assembly language swiftly and easily by developing a powerful system monitor in a step-by-step, top-down approach. Ten indispensable appendices contain all the necessary material to write 8080 or Z80 assembly language programs. 0 47108124-8 Jan. 1981 approx. 224 pp. $9.95

Implement all functions provided by CP/M with this working tool

USING CP/M»

Judi N. Fernandez & Ruth Ashley

A complete, detailed introduction to the use of the Control Program /Microcomputers software package for maximum capability and efficiency with any hardware.

"A marvelous addition to the CP/M literature... I only wish that I had had the book when I was starting out!"

—Alan R. Miller, New Mexico Tech

& Software Editor, Interface Age

0 47108011-X 1980 243 pp. $8.95

JOHN WILEY & SONS, Inc.

605 Third Avenue New York. NY 10158 In Canada: 22 Worcester Road. Rexdale. Ontario Prices subject to change without notice

Circle 224 on Inquiry card.

BYTE March 1981

297

(7a)

L-1

111

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Figure 7: Least-squares smoothed (nine-point) first derivatives of the square wave shown in figure 6a. Figure 7a shows the result for a linear and a parabolic first-derivative smoothing. (Both are the same.) Figure 7b shows the result for a cubic and quartic firstderivative smoothing.

298 March 19B1 © BYTE Publications lnc

Circle 159 on inquiry card.

At last thcDYNATYPER

TYPEWRITER INTERFACE!™

Turn your electric typewriter into a low cost, high quality hard copy printer. 1 year warranty

DYNATYPER - Rochester Data's patented* Computer/Typewriter Interface is the industry standard for typewriter output.

• 2 minutes to initially install and 5 seconds to remove or replace.

• You do not have to modify your typewriter. All factory war' ranties and maintenance agreements on your typewriter will be

honored.

• Compatible with all power carriage return typewriters having standard U.S. keyboard. The Dynatyper works with Selectrics (model 1) and most non-Selectrics (model 2). Please specify. Typewriterconversion between models takes 2 minutes and the kit (17 plungers) is available for a nominal fee.

• The Dynatyper is compatible with all majorword processing software. (Scripsit, Pencil, Applewriter, Easywriter, Magic Window, Visi-calc CCADBM, Supertext, Write On)

• lnterfacesavailableforTRS-80, APPLE, PET/CBM, OSI, Northstar, HP-85, H-89. Weighs only 3 lbs. Extremely portable.

• Delivery: Stock to two weeks. Price $499 for complete system. F.O.B. Rochester, Domestic. VISA and Master Card accepted. Call Ken Yanicky at 716-244-7804

•Pat. Pending

TM is a registered trademark of Rochester Data

3000 Winton Road South, Rochester, N.Y. 14623

incorporated

Circle 225 on Inquiry card.

NEW TARBELL S-100 CPU/IO BOARD

• Z-80'" will run at 2 or 4 Mhz

• 2 RS-232 Serial I/O ports

■ Powerful Memory Management

• Programmable Timer

• Full masked priority interrupts

• Has everything needed for MP/M"

• 6 month full warranty

Z-80 is a trademark of Zilog Inc.

MP/M is a trademark of Digital Research

950 Dovlen Place, Suite B Carson, CA 90746 Phone (213) 538-4251

From Ballet on Broadway

to Billiards m Dallas...

. . . people are finding unique ways to use the Powerful SciTronics REMOTE CONTROLLER

Whether it's the intricate lighting for a Broadway Ballet or the simple remote lighting of pool tables in a Dallas billiards hall, people are finding out SciTronics Remote Controller can meet their needs.

Here's Why:

0 Controls 256 BSR remote switches—not just 16 0 Hardware driven—requires minimum software 0 No ultrasonic link—prevents erratic operation 0 No BSR command module necessary

Real Time Clock gives Remote Controller an added dimension!

Real Time Clocks are now available to make your remote controller even more powerful. The RTC feature allows for energy consumption scheduling, event scheduling and much more. Your imagination is your only limitation when it comes to the ways which this RC/RTC combination can be used.

Real Time Clocks feature:

0 Lithium battery back-up

0 Crystal controlled accuracy (.002%)

0 Clock generates interrupts (seconds, minutes, hours) for foreground/background operation

0 Complete software in BASIC to Set and Read clock

S-100 CONTROLLER BOARD $159.

S-100 REAL TIME CLOCK BOARD $159.

ENCASED CONTROLLER $184.

(TRS-80, Apple II etc.) ENCASED CONTROLLER & REAL

TIME CLOCK (TRS-80, Apple II etc) $269.

APPLE II CLOCK BOARD $129.

send check SciTronics Inc.

or money 523 s. Clewell St., P.O. Box 5344

order to: Bethlehem, PA 18015

(215) 868-7220 Please list system with which you plan to use peripheral. Master Charge and Visa accepted. PA residents add sales tax. COD'S accepted.

Circle 226 on inquiry card.

BYTE March 1981

299

The New Literacy:

Programming Languages as Languages

"To be a good programmer today is as much a privilege as it was to be a literate man in the sixteenth century."

Andrei Ershov, USSR Academy of Sciences, Novosibirsk University

Many people would declare that Ershov is making an incongruous comparison: he compares the ability to read, a universally desirable trait, with the ability to program a computer, which fewer people deem to be a desirable trait. Stranger still, he compares reading, which is linked with the appreciation of literature and with the artistic use of language, to programming. Programming is the recording of arcane codes that make a computer perform some data manipulation. Such coding seems unconnected with art and language, yet he implies that it is. Consonant with this view, program-coding systems are called languages, but most people would find it difficult to specify any way in which a computer programming system merits the label language.

Some people are, in fact, hostile to the very idea that programming and programming languages have anything at all to do with creativity and language. Sometimes these people are confused between the computer and its human programmer, attributing programming to the computer rather than to human beings.

Programming languages are in fact languages in a meaningful sense of that word: they exhibit some of the complexity of form and function that natural languages do. Computer programming languages are much more than mere coding systems.

It is important that programming languages be recognized by lay people as languages. The ability to pro

Jon Handel

3 Gilmore Ct

Scarsdale NY 10583

gram computers, or at least to understand programming and computers in a general way, is important today, just as literacy was important in the sixteenth century. Those who lack the new literacy—computer literacy—will find increasing difficulty in participating effectively in political, professional, and business life. If you don't know what a computer can do, how can you decide whether we should sell them to the Soviets—or whether you should buy one to help around the house?

What a computer can do is greatly determined by its software—that is, by the programs it executes. The software is expressed in some programming language, and this is the subject to which we now turn.

To explore the nature of programming languages and examine the characteristics of natural language exhibited by programming languages, the term language must first be defined. A reasonable definition is that language consists of a set of symbols, sounds, and/or gestures, and a set of rules according to which these elements may be systematically combined to communicate an indefinite number and variety of thoughts and ideas. Usually, these symbols are combined into subunits called words.

and these words are then combined into sentences.

Notice that the communication effected by a language need not be between people; it may also involve machines. A computer programming language is a language which is most often used for communication with computing machinery. The instrument of communication is a computer program, which is a detailed, step-bystep set of directions for the computer to follow. The purpose of a particular program can be practically anything from printing mathematical tables to controlling oil refineries.

Three computer programs in common languages will be examined. Following this is an examination of the communicative function of programming languages and the grammar of programming languages. The examples presented will show that programming languages are much more than mere coding systems. They exhibit structural patterns and concepts that are both complex and in some ways parallel to patterns and concepts of natural languages.

(The several computer languages discussed in this article represent only a small fraction of the existing languages. Jean Sammet of IBM compiled a list of 167 major languages, noting the existence of numerous dialects of some of these (Communications of the ACM, December 1976, page 655). In an earlier roster (Communications of the ACM, July 1972, page 601), Sammet presented a chronological chart of languages ar

300 March 1981 © BITE Publications Inc

ranged by application area (eg: scientific computation, business data processing, experimental, etc). There are dotted, dashed, single, and double lines on the chart representing evolutionary changes from one language to another, as well as circles, squares, triangles, and three different type styles. The whole effect is that of a collapsed and tangled spiderweb. This complexity reflects the diversity of programming languages in use today.)

My sample programs deal with a specific problem. Imagine a computer user who wishes to calculate the reciprocals of some numbers. The user is sitting at a computer terminal and will use it to type in the numbers to the computer and receive the printout of the reciprocals. The programs illustrated will allow her or him to input a number X and have the computer print out the reciprocal of the number X, which is 1 divided by X. If the number X is 0, instead of printing the result of its computation, the program will print the message "Reciprocal of 0 does not exist."

BASIC Program

Listing 1 shows the reciprocal program coded in the BASIC language. When this program is typed into the computer as shown, and the command RUN is typed, the computer begins executing the program in the order of increasing line numbers. Line 10 instructs the machine to print the message in quotation marks exactly as it is written. The message reminds the user of what he will be expected to do. Line 20 causes the machine to print a question mark at the terminal and wait for the user to type in a number. Since the statement identifies the input as X, whatever number the user types will be placed in the variable X. The program can then use the number by referring to X.

In line 30, the program tests to see if X is equal to 0. If so, the computer does not execute the next statement in numerical order (line 40), but transfers control to line 70, as directed by the IF-THEN statement, and continues from there. Line 70 causes the printout of the message indicating that the reciprocal of 0 does not exist. Line 80, which is executed next, tells the computer that the program is over. The computer stops executing the program, and the user

may restart it and enter a new number, or run a different program altogether.

If X does not equal 0, then the program continues from line 30 on to line 40. Line 40 performs a computation of the reciprocal of X. This value is placed in the variable Y. Subsequent references to Y will use this computed value.

Continuing with the sequence, line 50 prints the numerical value of Y. If the number typed in were 2, then Y

It should be realized that even though programming languages

are used for communication In many

ways, they do not serve the same communicative functions as natural languages.

Programming languages are used for communicating technical procedures In a precise fashion.

would be printed as 0.5. Finally, line 60 causes the computer to stop executing the program. This line has essentially the same effect as the END statement in line 80.

ALGOL Program

Listing 2 shows the reciprocal program written in ALGOL 60. ALGOL 60 was created and formally defined in a report of an international committee which appeared in 1960. ALGOL 60 is important because its syntax was described using a formal notation. (See "An Introduction to BNF" by W D Maurer, BYTE, January 1979, page 116.) A different version of the language, ALGOL 68, appeared eight years later.

When execution begins, the first line of the program in listing 2 serves two distinct functions. The word BEGIN indicates the beginning of a program, and the phrase REAL X,Y declares that variables named X and Y will be used in the program. These two variables are to represent real numbers (ie: numbers that can have a

decimal point and a decimal fraction part, for example, 0.5, 6.2, or 4).

On the next two lines, the PRINT and INPUT directives work in a similar manner to those in the BASIC program, although the syntax is slightly different.

The IF-THEN-ELSE structure on the succeeding lines is different from the IF-THEN encountered in BASIC. The intent is the same, but the structure is more complex. In the ALGOL program, if X is equal to 0, the clause following THEN is executed [PRINT ("RECIPROCAL OF 0 DOES NOT EXIST")]; otherwise, the compound statement following ELSE is executed. This compound statement is composed of the two statements Y:=l/X, which assigns the value of the reciprocal of X to Y, and PRINT(Y), which prints out the value of Y. These two statements are bracketed by the pair of words BEGIN and END. This bracketing allows the two statements to be treated syntactically as a single statement group. If X does not equal 0, it is this compound statement that is executed.

Finally, we encounter the second END statement, which is paired with the BEGIN at the beginning of the program. This indicates the end of the program; execution of the program terminates.

Notice that, in contrast to the BASIC program, the physical layout of the ALGOL program displays its logical structure. The indentation shows the functional grouping of individual statements. This indentation, and the associated BEGINEND delimiters, are used to clarify the structure of ALGOL programs. [Editor's note: Indentation is also used to clarify structure in other languages, such as Pascal. . . . RSS]

Despite the differences between ALGOL and BASIC, one common characteristic of the two languages is that they are both similar to English and conventional algebra in the notation and verbs (eg: PRINT and INPUT) that they use. This similarity is not a characteristic of the language used for the third version of the reciprocal program, which makes extensive use of Greek letters and special symbols.

APL Program

The language of the third

March 1981 © BYTE Publications Inc

301

Circle 227 on inquiry card.

Z8000

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CRT: Dialogue 80'" interactive/edit terminal

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AMPEX Dialogue 80"

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^•k \ MICROCOMPUTER SYSTEMS V \ \ 5710 Drexel, Chicago, IL 60637

Listing 1: Reciprocal-determining program written in the BASIC language.

10 PRINT "INPUT NUMBER FOR RECIPROCAL";

20 INPUT X

30 IF X = 0 THEN GOTO 70

40 LETY=1/X

50 PRINT Y

60 STOP

70 PRINT "RECIPROCAL OF 0 DOES NOT EXIST."

80 END

Listing 2: Reciprocal program written in ALGOL.

BEGIN REAL X,Y;

PRINT ("INPUT NUMBER FOR RECIPROCAL");

INPUT (X);

IF X = 0 THEN

PRINT ("RECIPROCAL OF 0 DOES NOT EXIST.") ELSE

BEGIN

Y:=l/X;

PRINT (Y)

END END

Listing 3: Reciprocal program written as an APL function.

V RECIPROCAL

(1) ' INPUT NUMBER FOR RECIPROCAL'

(2) - (0 = X-D)/5

(3) □ -Y~-r-X

(4) - 0

(5) ' RECIPROCAL OF 0 DOES NOT EXIST.' V

reciprocal program is APL (A Programming Language), which was created by Dr Kenneth Iverson. The keys to its power are conciseness of notation and ability to deal with tables of data (arrays) as easily as with a single number. This conciseness can, however, make even a simple program difficult to read for the uninitiated.

Listing 3 shows our reciprocal routine written in APL. The first line, which is unnumbered, denotes the beginning of an APL function to be named RECIPROCAL. (Programs are called functions in APL. Once a function is entered into the computer, it is executed by typing its name, RECIPROCAL.) Execution proceeds starting with line 1.

Line 1 simply causes the computer to print the text that is within the single quotation marks.

Line 2 illustrates some of the complexity of the APL language. This line

does two separate things. The characters X— □ cause input from the computer terminal to be placed in the variable X for subsequent use. These three characters do the same thing as the seven characters INPUT X (counting the space) do in BASIC.

Continuing on line 2, once X has been assigned the numeric value input from the terminal, the expression 0 = X compares the value, now in X, against 0. If X is equal to 0, the expression produces the logical value 1; if X is not equal to 0, the expression produces the logical value 0.

This logical result of either 0 or 1 is still within the parentheses of line 2. The combination of this value (0 or 1) and the /5 to the right of the parentheses produces either a null vector or the value 5.

The arrow -* at the left of line 2 is followed by the expression in parentheses, whose value is either the null vector or 5. The arrow is known as

302 March 1981 © BYTE Publications Inc

the branch arrow; to branch is to change the order of execution of program statements. The branch arrow does this as the GOTO statement does in BASIC. If the value following the arrow is 5, indicating that X is equal to 0, the arrow causes a branch to line 5. If the value is the null vector, indicating that X is not equal to 0, no branch at all is taken and execution proceeds to line 3 of the function. In summary, line 2 performs the functions of the following two lines from the BASIC version of the program:

20 INPUT X

30 IF X = 0 THEN GOTO 70

Line 3, which should be read from right to left, calculates the reciprocal of X (written in APL as -*-X), places this value in the variable Y, and then prints Y. This line functions as do the lines:

40 LET Y = l/X 50 PRINT Y

in the BASIC program.

Line 4 seems to direct a branch to line 0. Actually, — 0 is an idiom that means branch out of the function entirely—in other words, stop the program.

Finally, line 5, which is only executed if X was found equal to 0 in line 2, directs the computer to print the text in quotation marks. After line 5 is executed, the computer encounters the V symbol, which denotes the end of the program.

Uses of Programming Languages

Programming languages, like all languages, are used for communication in a variety of ways. Two broad classifications are communication between people and machines, and communication between people and people.

The way in which people use programming languages to communicate their desires to computers is selfevident. If the user desires computation of reciprocals, a program is written for this computation in a language understood by the particular computer at the programmer's disposal. It should then be entered into the machine. The aspect of communication is the same for more difficult tasks.

Programming languages are also

used for communication between people. For example, since many programming projects involve more than one person, those involved must communicate. Naturally, much of this communication requires transmission of segments of the program being worked on.

Another example of this type of communication is the publication in professional journals of algorithms expressed by programs. One of the most popular languages for such communication is ALGOL 60. The ALGOL 60 report, by defining a publication language differing slightly from the hardware representation, explicitly recognizes the two facets of programming language communication.

It should be realized that even though programming languages are used for communication in many ways, they do not serve the same communicative function as natural languages. Programming languages are used for communicating technical procedures in a precise fashion. Natural languages are not very well adapted to this type of communication. Indeed, natural languages, when used for communication of detailed instructions, are often augmented with charts, diagrams, pictures, and mathematical expressions.

Grammar and Syntax

The noun of a programming language is the variable, which is conceptually an object or storage cell capable of holding information. The primal variable, seen in the reciprocal programs, can hold only one number. There are two distinct directions in which this concept of variable may be extended: by allowing different types of data to be stored in the variable, or by allowing different amounts of data to be stored.

In most languages, if different types of data are to be stored in different variables, the variables themselves must possess the attribute of data type. This attribute is an identification that a particular variable can be used to store a particular type of data. Consider some of the data types offered by ALGOL 68 as shown in table 1. For example, to declare in an ALGOL 68 program that I and "class size" (a single variable; lowercase and spaces are okay) are to be variables capable of storing an integer; COST, to be capable of storing

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a real number, and NAME, to be capable of storing a character string (such as "John Smith"); the programmer would use the following statements:

INT I, class size; REAL COST; STRING NAME;

The structure of these declarations is:

predicate-adjective subject

with an omitted linking verb. This structure is similar to the English structure:

subject is predicate-adjective

Data types are attributes of variables and are specified in the same way as an attribute of a noun in English. (The parallel is even stronger in Russian, since that language usually omits the linking verb in the present tense.) The names of the data types (INT, REAL, CHAR, STRING, and others) are adjectives in the grammar of ALGOL 68.

In addition to the four data types outlined above, ALGOL 68 offers a number of other data types, each of

which is an extension of the concept of data type in a distinct direction. One class of data type that is of a particular interest is reference-to modes. (Mode means data type.)

Such modes can be viewed simply as the recognition of the difference between nouns and pronouns. A noun, in English, is a symbol for some person, place, or thing. A pronoun is a reference to a particular noun, termed the referent of the pronoun. With this distinction in mind, consider the following sequence of ALGOL 68 statements:

BEGIN INT I,J; I:=2; J: =1+3;

END

This seems simple enough, but consider carefully the statement J: = I + 3. What is being added here? The 3, certainly, is being used as it stands, but the I really is not. The I refers to a number (2 in this case) and it is actually this number that figures in the addition, 2 + 3. The constants 2 and 3 in this program are the nouns and the variables I and J are pronouns.

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The declaration INT I,J is a shorthand: it does not signify that I and J are themselves of type INT, but that they are to refer to objects (ie: numbers) of type INT. The variables themselves are of mode (type) REF INT, meaning reference to integer. REF REAL, REF CHAR, REF STRING, etc are all possible. These different types of reference-to modes are analogous to pronouns of different genders and cases in human languages.

The distinction between variables and the values to which they point may strike you as pointless. Indeed, some languages—BASIC, APL—ignore the distinction. Others — ALGOL 68, Pascal—don't. Like genders and cases in Russian, pointer variables (a more common term than reference-to) can be a pain to learn, but once learned, a subtle and useful tool.

The concept of variable type or mode is only one way in which the concept of variable may be extended. Another extension is to remove the restriction that a variable hold only one item. Such variables must have some internal organization or structure to allow access to subsets of the stored data. One type of structured variable is the array.

In an array, all data items are of the same type (eg: all integers) and are arranged in a regular rectangular pattern. A one-dimensional array is called a vector or list; an example is:

95 78 99

This three-element vector could represent the final examination grades of three students; the first scored a 95, the second a 78, and the third a 99. Though all elements of the vector are integers, the programmer can just as easily work with a vector of real numbers, of characters, or of any particular type. To create this vector of integers for use in an ALGOL 68 program, use the following statements:

[1:3] INT GRADES; GRADES: = (95,78,99);

The first statement declares GRADES to be a vector of integers, the elements of which are numbered from 1 to 3. The second statement assigns to GRADES the three grades 95, 78, and 99. It is clear that a vector is called a one-dimensional array

304

March 1981 © BYTE Publications Inc

because it is an array of numbers that extends in one direction only (mathematically, along one dimension).

An example of a two-dimensional array, or matrix, is:

96 95 98 95 67 83 72 78

97 95 99 99

Each row could correspond to the test grades of a particular student; thus, student number 1 scored a 96 on the first test, a 95 on the second, a 98 on the third, and a 95 on the final exam. A matrix is called a two-dimensional array because it extends along two directions, horizontal and vertical.

Higher-dimensional arrays are also possible, though clumsy to represent on the printed page. It is even possible in ALGOL 68 to have arrays of arrays, arrays of arrays of arrays, and so forth.

The concept of array is analogous to that of plurals in natural languages. At one stroke, a sentence such as Cheshire cats always grin makes a statement about all members of the set of Cheshire cats. Similarly, the expression Y: = GRADES —5 subtracts 5 from all elements of GRADES at once, setting Y equal to (90,73,94).

There is also a parallel between array subscripting and prepositional phrases. Consider again the vector GRADES. To access the first element of GRADES by itself, the subscripts to the elements in GRADES must be assigned. In ALGOL 68, this is written GRADES [1J.

GRADES [1] is the single number 95; it may be printed or used in calculations just like a single variable. The construction [1] may be viewed as a prepositional phrase, the brackets being the preposition, and the 1, its object. The preposition [ ] shows the relationship between the two nouns GRADES and 1. Interestingly, the way GRADES [1] is read aloud reflects this structure: "GRADES sub [meaning subscripted by] one."

Just as a noun cannot communicate much without verbs, a variable is useless without the verbs of programming languages, operators and functions. Operators are the symbols used in mathematics and programming languages to represent arithmetic and other operations. Thus, +, —, and * (multiplication) are all operators. In conventional notation, operators are

placed between their operands (X + Y) if there are two, or in front of them (—X) if there is one.

Functions, on the other hand, precede and enclose their operands. For example, the function SQRT(X) in FORTRAN computes the square root of X. A function can have more than one operand. An example of this is the function MAX(X1, X2, X3, . . .), which selects the largest of its indefinitely many operands. The distinction between functions and operators is fundamentally one of notation; operators will be used in the examples presented here.

Operators change their actions depending on the data types of their operands. For instance, there are differences in the accuracy of addition of real operands and of integer operands, while addition of string operands is actually concatenation (eg: "John" + " Smith" yields "John Smith"). In general, ALGOL 68 actually allows total redefinition of operators based on the data types of their operands.

Operators can also change their actions depending on the structure of their operands. To use an operator with arrays and inhomogeneous structures, ALGOL 68 requires prior definition of the operator's actions, which allows a great deal of flexibility. In contrast to ALGOL 68, the APL language provides definitions such as "the addition of two arrays is the addition of their corresponding elements"; the programmer cannot redefine operators in APL. The PL/I language has a different solution; to add correspondingly named elements in two inhomogeneously structured variables, A and B, one uses:

C=A + B,BYNAME;

The keyword BY NAME functions as an adverb, modifying the + operator.

APL, in addition to functions (such as + and —, which most languages call operators) which act as simple verbs, also has operators, which act as auxiliary verbs. These operators (again, note the special meaning in APL) modify the results of regular functions in a systematic way. For example, + is the familiar addition function. Applied to two vectors, it yields the sum of corresponding elements (eg: 3 4 5 + 689 produces 9 12 14). The reduction operator, /, is an auxiliary verb. Juxtaposed, as +/, these

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two form a new function, "plusreduction," that operates on a single vector and produces the sum of its elements (eg: + /3 4 5 yields 12). The + / function reduces its operand to a single number by addition.

These complex verbs, nouns, adjectives, adverbs, pronouns, and prepositions all fit into equally complex syntactic structures. As with English, there is a range of syntactic complexity; some languages, such as BASIC, have a very simple set of syntactic patterns. Other languages encompass some very complex and powerful syntactic structures.

Probably the simplest syntactic form is that of many BASIC statements, which may be characterized

imperative-verb object

Examples of this form are PRINT X, INPUT Y, and GOTO 200. The object may also be a verbal phrase, as in PRINT X+ Y, in which the verb in the verbal is the + operator.

A few forms of greater complexity are found in BASIC. One of these is the IF-THEN statement, an example of which is:

INT integer

REAL rational number [it may have a fractional component]

CHAR character [a single character only]

STRING string of characters [text string]

Table 1: Data types which may be assigned to variables in the ALGOL 68 language.

IF X = 3 THEN PRINT "X IS EQUAL TO 3."

This is a more complex form than the first for two reasons. First, it uses a conjunction-conjunctive adjective pair, IF and THEN; second, the phrase following THEN can be any BASIC statement. This makes the IFTHEN statement, in the terminology of English grammar, a complex sentence.

Syntactic patterns much more complex than these are found in ALGOL 60 and 68. An example from ALGOL 60 is the statement:

X: =

= 2 + (IF Y = ELSE 6)

1 THEN 3

This statement assigns to X the value 5 (2 + 3) if Y is equal to 1, and the value 8 (2 + 6) if Y is not equal to 1. An IF-THEN-ELSE clause may be

used wherever a noun (ie: numerical or character value) is required by the syntax of ALGOL 60. This freedom is restrictive compared to the rules of ALGOL 68; there, not only IF-THENELSE statements can be used as clauses in place of nouns, but any valid statement can be so used.

Statements and phrases may be combined in ways such as:

k: = (INTi; read(i); i + 1)

This statement declares the variable i to be of type INT, accepts a value for i as input from some device (possibly a computer terminal), calculates the value of i + 1, and finally assigns this value to the variable k. One of the most impressive aspects of ALGOL 68 is that the labyrinthine syntax of the entire language is rigorously defined using a formal notation.

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As has been implicit in the above discussion, the meaning of a statement (English or programming language) is often determined by the meaning of the individual words (such as grin or PRINT) and the syntactic operations which combine them. This is made light of by Lewis Carroll in his poem "Jabberwocky," which begins:

'Twas brillig, and the slithy toves

Did gyre and gimble in the wabe:

All mimsy were the borogoves,

And the mome raths outgrabe.

This verse is amusing because we understand the syntax, while the words, though suggestive, are meaningless.

In the realm of more standard language, there are constructions whose meaning is not simply a composition of individual word meanings. Such expressions are called idioms. A sentence like The FBI kept tabs on Bill's unicorn has nothing to do with actually sticking plastic tabs on a unicorn. And thinking about The cat got his tongue in such literal terms would lead to an anxiety attack.

In programming languages, too, there are idioms. In APL, there are the constructions —, — 0, and —(null vector), all of which are idioms for special types of program branching. In ALGOL 68, there are operators such as +=: (plus and becomes). A+ = :l is equivalent to A = :A + 1, and instructs the computer to take the value of A, add 1 to it, and store the result back into A. These are truly idioms, as their meanings cannot be derived directly from the meanings of their individual elements.

Good examples of expletives may be found in both ALGOL 68 and FORTRAN. In ALGOL 68, the SKIP statement is an expletive; it does nothing and is explicitly undefined. A similar example in FORTRAN is the CONTINUE statement, the execution of which also has no effect. In practice, CONTINUE is used in only one particular context, while SKIP is used in many different contexts.

While idioms, expletives, and syntax in general reveal the similarity between programming languages and natural languages on the level of the word and the sentence, there are also similarities on the level of the paragraph and the document. The paragraph in ALGOL 60 is the block,

which is a sequence of statements beginning with BEGIN and variable declarations (REAL, INTEGER, etc), and ending with END. This is similar to a paragraph of English in several ways. It has a clearly marked beginning and end. It is required to state at the beginning the objects (variables) it will be working with, just as a good paragraph should declare its subject at the beginning. Finally, a good block deals with only one phase of the problem being solved by the program, just as a paragraph should deal with only one aspect of the idea being discussed.

The analogy between programming languages and natural languages at the level of whole documents is seen by comparing computer programs with books. Both usually have titles; some programming languages—APL and Pascal—actually require them. Many books have a dust-jacket blurb or preface to make the book easier to read and use. Good computer programs have comments written into the code for the same purpose.

You may be surprised to find paragraphs, idioms, expletives, and so forth in programming languages, if you have thought of them only as characteristics of natural language. Throughout this discussion, however, we have seen how closely programming languages parallel natural languages. Therefore, the existence of idioms and similar attributes in programming languages is a nearly predictable situation.

Importance of Similarity

Granting that programming languages are languages in the same sense as English or Mandarin, the question that follows is: does this make any difference to working programmers? Yes, it makes a great deal of difference, for it leads to the concept of programming style, with associated benefits.

The concept of programming style follows naturally. Just as English is a tool for which there are different uses and styles, so too are programming languages tools for which there are different uses and styles. Further, just as in English there are some writing styles that are superbly clear and efficient, while others are not, there are some programming styles that are more desirable than others. Aesthetic considerations indicate that a

desirable style is a clear and concise one. But why should this interest the working programmer, who is just interested in doing a job, not in creating a work of art?

Too many programs are written today without consideration for later revisions that may be necessary. It is as though these programs will never be read or changed. The inevitable result of such a programming practice is programs that do need to be patched, altered, and debugged to make them work, and programs that are so incomprehensible that they can be changed to meet future requirements only with great difficulty. Worse, the result may be a program that works 99 times out of 100. On that hundredth time, the program may fail and produce incorrect results that are accepted as true. Or perhaps it will be obvious, as bank accounts are jumbled, an oil refinery burns, or a spacecraft explodes upon launch, that something is indeed amiss with the computer programs in use.

Working programs, programs that can be confidently (and even mathematically) labeled correct, are serious business in a society in which computers are performing more and more functions of ever greater importance. For this and other reasons related to the costs of debugging a poorly written program, structured programming (which advocates a clear and systematic approach to programming) has become popular.

Many programmers still do not write programs that work correctly the first time. There is still much to be done before good programming is nearly universal. However, better programming languages are being developed, more programmers are developing a clear and functional programming style, and more programs work the first time. ■

References

1. Ershov, A P. "Aesthetics and the Human Factor in Programming." Communications of the ACM, July 1972, pages 501 thru 505.

2. Kernighan, B W and P J Plauger. The Elements ot Programming Style. New York: McGraw-Hill, 1974.

3. Ledgard, H F. Programming Proverbs. Rochelle Park NJ: Hayden Book Co, 1975.

4. Naur, P (editor). "Revised Report on the Algorithmic Language ALGOL 60." Communications of the ACM, January 1963, pages 1 thru 17.

March 1981 © BYTE Publications lnc 307

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Model 299B: Dual headed drives, total 3.2 MB unformatted $2,300.

Model 277: Dual 8 inch drives, voice coil positioned, IBM compatible, 1600 K BYTES

per drive, unformatted $1,210.

Slimline cabinet and power for either 277or299 $ 300.

DRIVES Dual 800R Shugarts power supply, cabinet and fan, A & T. $1,250. Qume data track 8, double sided, power supply, fan cabinet, A & T .... $1,650.

MPIB51 ... $265. Shugart $525.

B52 ... $365. B92 $500.

HAZELTINE1500 $925.

1510 $1,030.

S AMPEX DIALOGUE 80 CRT $950.

Removable keyboard, 2 page memory, j (4 optional), block transmit.

CENTRONICS 737 $780.

Same as TRS-80 Model IV

Apple serial/parallel interface . . . $195.

EPSON MX80B $550.

TELEVIDEO SMART CRTs

912 $780. 920

$850.

IMS MEMORY 16 K static $285.

32 K static $585.

64 K Dynamic with parity $950.

TEI MAINFRAMES, S—100

12 slot, table top $500.

22 slot, table top $670.

Rack mounts, add $ 50.

50 Hz, 220 volts, add $ 50.

TARBELL

Double density controller $420.

Cables $ 40.

Complete TARBELL Product Line Available.

3M SCOTCH® Diskettes

Buy the best. 8" or 5" (Model 740 or 744)

One box of ten diskettes $29.

Five boxes, each $26.50

I WE EXPORT:

Overseas Callers:

TWX 710 588 2844

Phone 212 448-6298 or Cable: OWENSASSOC

SEE OUR AD FOR 8" FLOPPY NORTH STAR SUBSYSTEM ON PAGE 28

JOHN D. OWENS

Associates, Inc.

12 Schubert Street Staten Island, New York 10305

212 448-6283

212 448-2913

212 448-6298

data-processing professionals is offered by WPI. For a detailed brochure, write to the Office of Continuing Education, Worcester Polytechnic Institute, Worcester MA 01609, (617) 753-1411, attn: Ms Ginny Bazarian.

March-November

Advanced Data Processing Workshops, Deltak Inc, various cities throughout the US and Canada. These 5-day workshops are aimed at data-processing training managers responsible for the management and administration of data-processing training and involved in planning, monitoring, evaluating, and reporting to upper management on the status of the training. For a schedule of dates and locations, contact Deltak Inc, 1220 Kensington Rd, Oak Brook IL 60521, (312) 920-0700.

March 8-11

TI-MIX 1981, Marriott Hotel, New Orleans LA. This is a conference for Texas Instruments equipment users. Thirty-six sessions consisting of individual presentations, panel discussions, and workshops are planned. Two exhibit rooms featuring the latest computer equipment from Texas Instruments will be open. Contact TI-MIX, M/S 2200, POB 2909, Austin TX 78769, (512) 250-7151.

March 11-13

Business- and PersonalComputer Sales and Exposition and New York Business Show, Madison Square Garden, New York NY. For details, contact Produx 2000 Inc, POB 2000, BalaCynwyd PA 19004, (215) 457-2300.

March 14

The Fourth Annual PACS Computer Games Festival,

LaSalle College Ballroom, Philadelphia PA. This event is sponsored by PACS

308

March 1981 © BYTE Publications Inc

(Philadelphia Area Computer Society) and the LaSalle College Physics Department. Presentations on computer-aided learning will be featured. Contact Stephen A Longo, Physics Department, LaSalle College, Philadelphia PA 19141, (215) 951-1255.

March 17-20

The Fourteenth Annual Simulation Symposium,

Tampa FL. Papers describing digital discrete simulation and other techniques will be read. This symposium is a forum for the exchange of ideas and techniques in computer simulation. Contact Annual Simulation Symposium, POB 22621, Tampa FL 33622.

March 20

Digital Computer Association Annual Meeting,

Pacifica Hotel, 6161 Centinela Blvd, Culver City CA. Cocktails, dinner, and the annual meeting are the features of this gathering. For more information, contact Mary Rich, 731 Bayonne St, El Segundo CA 90245.

March 23-25

Office Automation Conference, Albert Thomas Convention Center, Houston TX. This conference presents seminars on the concepts and the methods behind the latest office technologies and an exhibition of office equipment. Contact Office Automation Conference, POB 9659, Arlington VA 22209, (703) 558-3617.

March 24-27

Printemps Informatique,

Palais des Congres, Paris, France. This is an electronic data-processing exhibition for computer OEMs (original equipment manufacturers). Additional information is available from Kallman Associates, 30 Journal Sq, Jersey City NJ 07306, (201) 653-3304.

March 24-26

The Southwest Semiconductor Exposition, Phoenix

Civic Plaza Convention Center, Phoenix AZ. More than 140 equipment and materials makers will exhibit semiconductor, hybrid, and printed-circuit board production, processing, and test equipment. Contact Cartlidge & Associates Inc, 491 Macara Ave, Suite 1014, Sunnyvale CA 94086, (408) 245-6870.

March 31-April 2

Cincinnati Business Show,

Cincinnati Convention

Exposition Center, Cincinnati OH. Office equipment and services, including automated systems, communications, computers, telephone systems, word processing, data processing, printing equipment, and other office supplies, will be featured. A program of business seminars is also scheduled. Contact Ray G Nemo, 5679 Creek Rd, Cincinnati OH 45242, (513) 531-5959.

April 1981

April 1-2

Communications in the Twenty-First Century, Philip Morris Operations Center, Richmond VA. This conference focuses on technological advances and their economic, political, social, and psychological implications. Elie Abel, Professor of Communications at Stanford University and Lord Briggs, provost of Worcester Col

TELETYPE MODEL 43 INVENTORY SALE

TELETYPE

Model 4320 AAA $ 885.

220V. model with transformer installed

inside cabinet $ 985.

Model 43ASR, 8 level, 1" tape . $2,595. Limited supply of Model 45 available.

TELEBUFFER 43 ASR $945.

Circuit card designed for internal installation in the Model 43 Teletype. Changes the 43 into a buffered send/ receive device, enabling it to function as a Telex without paper tape. Provides from 4K to 16K bytes of internal memory for storage of message. Contents of memory may be edited and manipulated in preparation for transmission. Options include forms control and answer back.

IBM 3101 CRT Model 10 $1,195.

Model 20 $1,395.

Selectric-like. detached keyboard. 9x16 dot matrix. Maintenance contract from IBM only $70 per year

ITHACA INTERSYSTEMS

Full S-100 IF.EE Compatibility! Full 24 address bits. DMA disk controller. SYSTEM 2A includes 20 slot mainframe with front panel, 64K Dynamic RAM. Z80 CPU. 4 MHZ, extended addressing capability. 4 parallel, 2 serial I/O floppy controller. Our discounted price $3,415.

MARINCHIP SYSTEMS M9900 Elegant 16 bit CPU. 5-100 compatible, rnulti user, multi processor operating

. system. BASIC. FORTH, META, PASCAL, Word processor, text editor. CPU kit and software package . $ 550.

Assembled $ 700.

Complete system, 64KB,

twodrives $5,400.

MICROANGELO $2,280.

High resolution graphics system. 15", 22MHZ, green phospher screen, 72 key keyboard; includes complete cabling and software. From SCION. S-100 Graphics card $ 960.

GRAPHICS SOFTWARE

On line, real time, for the M9900 to drive the Microangelo. For use in design of PC board masks, 1C masks and other applications.

CORVUS HARD DRIVES

We are the S-100 CORVUS dealer in the New York area. Demonstrations by appointment. MODEL 11, Hard Disk System. 54,820.

Mirror Backup System $ 715.

Host Multiplexer S 675.

MULTI-BUS

Z-8000 CPU and supporting boards. From Central Data Corp. Complete systems starting at $6,500.

UPGRADE DEC LA 35/36... $750. Increases baud rate to 1200. Microprocessor controlled. Many options available. Enthusiastic user response. Longterm reliability. From DataSouth.

COMPUTER TO COMPUTER COMMUNICATIONS

Enables communications from a micro to a terminal or to another micro, mini or maxi computer. Modes of operation: TERMINAL (your system acts like an intelligent terminal), FILE-TO-FILE. LOCAL (Disk commands), Full/Half Duplex on 8" or 5" disks. COM to COM mode does full CRC 16 error check and retransmits block on error. Object Code $75. Source Code S250.

THE MAX BOX

8" Dual Drive Cabinet complete with power supply and fan. Will hold Qumes, Shugarts or Siemens. Excellent design and engineering - $400.

CAT from NOVATION

Originate/Answerback $175.

CAT-D : $185.

Connects directly to telephone line with a plug-in jack. Eliminates need for acoustic coupler.

WE OFFER A FULL RANGE OF EXPERT CONSULTING SERVICES COVERING ALL AREAS OF COMPUTER APPLICATIONS AND SYSTEMS

JOHN D. OWENS

Associates, Inc. SEE OUR AD ON FACING PAGE

March 1981 © BYTE Publications Inc 309

Circle 229 on Inquiry card.

r

DISK DRIVES

8'

Shugart 801R

Sgi/Sided Dbi/Den

$395.00

Qume Dalatrak 8" dbl sided, dbl density QME-8DS (851R) compatible... $625.00 Pkg of two $1150.00

51/4"

MPI-B51 MPI B-51 $250.00

Sgl Sided Sgi/Dbl Den

Exact Replacement for SA-400

MPI-B52 MPI B-52 $350.00

Dbl Sided, Dbl Den

MPI-B91 MPI B-91 $375.00

Sgl Sided, Dbl Den, 77 tracks

Shugart SA400 SMU-SA400 $250.00

Sgl Sided, Dbi/Den

QT DISK PACKAGES

DDC-88-1 Dbl Den Controller, A&T, two 8" dbl den drives (801 R) CP/M® 2.2 cabinet, power supply & cables SPECIAL $1395.00

DDC-88-2 Two 801R disk drives with cabinet, power supply, fan &

cables $1100.00

DDC-88-22 Two DT-8 Qume drives with cabinet, power supply, fan

& cables $1500.00

DDC-88-3 Cabinet with power supply, fan & cables $250.00

DDC-88-4 Cabinet only $75.00

COMPUTER SYSTEMS IMC. 15620 South Inglewood Ave. Lawndale, California 90260 (213) 970-0952

WE ACCEPT M/C, VISA, AM EXP PLACE ORDERS TOLL FREE

1-800-421-5150

(CONTINENTAL U.S. ONLY)

(EXCEPT CALIFORNIA)

CP/M Is a trademark of Digital Research

FINDING SOLUTIONS

AND BEING COMPETITIVE

IS OUR BUSINESS.

Having problems and looking for a

computer to help solve them?

Are you finding computer dealers

come in one of two ways? Either

Full system support with Full price

or Take it or Leave it with Low

price. At Omega we don't believe

that you should have to make a

choice. Yes, we're in business to sell

products but also, to solve your

problems. Our prices will be the

lowest possible. Our support and

product quality will be second to none. Check out our Mail Order prices in this

ad (our retail prices will be higher). See if you don't agree with our first claim.

For our second claim, call us with your data processing needs and problems.

Better yet, come in and see us. Finding solutions and being competitive is our

business. We never forget either of them.

'apple computer

' Authorized Dealer

APPLE III SCALL

APPLE II "PLUS" 48K $ 1169.95

HEWLET PACKARD 85 or 63 $ CALL

APPLE II ACCESSORIES:

Disk II with controller $ 535.00

Disk II 2nd drive 455.00

Graphics Tablet 665.00

Language System with PASCAL 395 00

Silentype Printer W/Int 526.00

Integer Firmware Card 152.00

Microsoft Z-80 Softcard 259.00

Videx videoterm 80 col Card 279.00

Sanyo 12" Green Monitor 269.00

Supplies:

Scotch Diskettes - Best of Quality! price per box of (10)

744-0, 10. 32 $ 27.00

740-0 SS/SD 0 Sector 31.00

741-0 SS/DD 0 Sector 37.00

743-0 DS/DD No Format 44.00

New Products:

Videx L/C Adapter 110.00

Microsoft 16K RAM Card 169.00

D.C. Hayes Micromodem II 315.00

Novation DCAT Modem 195.00

EPSON MX-80 CALL

Mail Order Terms of Sales: Price based on prepaid orders. NO COD'S. Visa or Master Charge orders add 3% to purchase

Krice. Allow 14 working days for personal and company checks to clear. Order under $100.00 add $3.00 for shipping and andling. All orders (unless specified in ad) within Continential U.S. shipped U.P.S. no charge. APO or out of Continential U.S. write or call for shipping charges. All prices subject to change and all offers subject to withdrawl without notice. CA residents add 6% sales tax.

OMEGA MIQFO 3CMPUTEFS

The Problem Solving Company

3447 Torrance Boulevard • Torrance, California 90503 • (2131 370-9456

lege, Oxford, England, are keynote speakers. For information, contact the Manager of Media Relations, Philip Morris Inc, 100 Park Ave, New York NY 10017.

April 1-3

Assuring Quality in Electronic Data Processing Applications, McCormick Inn Hotel, Chicago IL. The objective of this conference is to explain the methods, tools, and techniques that are valuable in improving the quality of computerized applications. Tutorials cover the areas of quality assurance; managing structured design; and designing, implementing, and enforcing application standards. Contact DPMA Quality Assurance Conference, 12611 Davan Dr, Silver Spring MD 20904, (301) 622-0066.

April 3-5

The Sixth West Coast Computer Faire, Civic Auditorium, San Francisco CA. The Faire, a major personal-computing event, has continually attracted larger and larger numbers of exhibitors and attendees. A full program of talks plus a large display of hardware and software are featured. For more information, contact Computer Faire, 333 Swett Rd, Woodside CA 94062, (415) 851-7075.

April 6-10

Tutorial Week—East, Orlando Marriott Inn, Orlando FL. Tutorials on VLSI (very large-scale integration) and microprocessors and graphics, software-engineering methodology and testing, and distributed computing and networks will be presented. For IEEE members, the cost is $400; for nonmembers, the cost is $475. Contact Tutorial Week—East, POB 639, Silver Spring MD 20901, (301) 439-7007.

April 7-8

Top Secrets '81, Pointe Resort, Phoenix AZ. Honeywell's annual computer security and privacy conference. Many author

310 March 1981 © BYTE Publications Inc

Circle 230 on inquiry card.

ities in the field of data security will discuss the business and legal impact of the latest incidents in computer crime and abuse. The conference fee is $500. Contact the Security Symposium Registrar, Honeywell Information Systems, M/S T-99-4, POB 6000, Phoenix AZ 85005, (800) 528-5343.

April 7-9

Computerized Office Equipment Expo, O'Hare Exposition Center, Rosemont IL. More than 200 exhibitors will feature their office equipment at this show. Executives and administrators from wholesale, retail, commercial, financial, and industrial establishments are invited, along with the general public. Contact Industrial & Scientific Conference Management Inc, 222 W Adams St, Chicago IL 60606, (312) 263-4866.

April 7-9

Electro/81, New York Coliseum and Sheraton Centre Hotel, New York NY. Electro/81 will feature computers and computer-related equipment, plus seminars on components, devices, and materials; computer communications; memories; office automation; speech; and more. Contact Electronic Conventions Inc, 999 N Sepulveda Blvd, Suite 410, El Segundo CA 90245, (800) 421-6816; in California (213) 772-2965.

April 13-16

The Fifteenth International Symposium on Minicomputers and Microcomputers, MIMI '81, Sheraton Hotel, Mexico City, Mexico. The scope of this symposium covers hardware, software, distributed processor architecture, computer networks, telecommunications, real-time applications, education, and more. Contact Ing. Jorge Gil, Academic Secretary, MIMI Symposium, IIMAS-UNAM, Apartado Postal 20-726, Mexico 20 D F, Mexico.

April 26-30

Saudibusiness '81, Riyadh, Saudi Arabia. This show has

System Log

3-/Q £/n. - IW^&^ /)tHu+u j

£/KUot sf£JL/<SUUo( euut

A+f&&*H ^tttek 0* ^&*u^

DIAGNOSTICS \\

Diagnostics II is SuperSoft's expanded Diagnostic package.

Diagnostic II builds upon the highly acclaimed Diagnostics I. It will test each of the five areas of your system:

Memory Terminal Printer CPU Disk

Every test is expanded.

Every test is "submit"-able. A "submit" file is included in the package which "chains" together the programs in Diagnostics II, achieving an effective acceptance test. All output can be directed to a log file for unattended operation, for example over night testing. Terminal test is now generalized for most crt terminals. A quick-test has been added for quick verification of the working of the system.

The memory test is the best one we have encountered. It has new features, including:

• default to the size of the CP/M Transient Program Area (TPA)

• printout of a graphic memory map • burn in test

• bank selection option • memory speed test Diagnostics-ll still includes the only CPU test for 8080/8085/Z80.

A Spinwriter/Diablo/Qume test has been added, which tests for the positioning and control features of the Spinwriter/Diablo/Qume as well as its ASCII printing features. (Serial Interface only)

And, as with all SuperSoft products, a complete online HELP system and user manual is included.

Price: $100.00 (manual only): $15.00

Requires: 32K CP/M

CP/M Formats'. 8" soft sectored, 5" Northstar, 5" Micropolis Mod II, Vector MZ, Superbrain DD/QD

All Orders and General Information:

SUPERSOFT ASSOCIATES

P.O. BOX 1628

CHAMPAIGN, IL 61820

(217) 359-2112

Technical Hot Line: (217) 359-2691

(answered only when technician is available)

CP/M REGISTEREDTRADEMARKDIGTAL RESEARCH

SuperSoft

First in Software Technology

March 1981 © BYTE Publications Inc 311

#11 SOFTWARE

•* new items/new prices.

FANTASTIC PRICE PROTECTION POLICY

We'll match any advertised price on any item that we carry. And if you find a lower price on what you bought within 30 days of buying it, just show us the ad and we'll refund the difference.

It's that simple.

Combine our price protection with the availability of full professional support and our automatic update service and youhavethe Ultimate Software Plan.

It's a convenient, uncomplicated, logical way to get your software.

CP/M users:specify disk systems and formats. Most formats available

£373.

$ 59/S20 $ 59/$20 $ 59/$20 $118/$57

$149/$25 $169/$25

CP/M>

OSBORNE «I General Ledger**. . . Acct Rec/Acct Paytt

Payroll w/Cost#

Buy 2 get 1 free ...

All 3S.CBASIC-2 $199/$71

DIGITAL RESEARCH CP/M 2.2 Northstar

s CP/M 22 Micropolis

*- CP/M 2 2 Durango

F-85 $169/$ 25

CP/M 2.2 Cromemco $189/$25

CP/M (otherversions) Call

PL/l-80 $459/$35

Mac * 85/$ 15

Sid $ 65/$15

Z-Sid S 95/$15

Tex $ 70/$ 15

DeSpool $ 50/$10

MICROSOFT

Basic-80 $294/$30

Basic Compiler $334/$30

Fortran-80 $384/$30

Cobol-80 $574/$30

Macro-80 $144/$20

Edit-80 $ 84/$20

MuSimp/MuMath. ... $224/$25

MuLisp-80 $174/$20

MICRO DATA DASE SYSTEMS HOBS $250/$40

^ MDBS $795/$40

Other. Call

S.O.F.T.W.A.R.E.

MicroTax'}.

Federal individual $749/$50

Federal corporate $249/525

State individual $249/525

TCSt

x- General Ledger $ 79/$25

S Acct Receivable. ....$ 79/$25

S Acct Payable. $ 79/$25

s Payroll $ 79/$25

$269/$99

THIS MONTH S SPECIAL: T.I.M. DBMS JUST $299.

Terrific for inventory, mailings, financial, you-name-it! Menudriven. auto»sort, 32000 records per file, any number of files, and dynamite documentation!

• WordStar/Mail-Merge $434/$85

x" DataStar $279/$60

*• Word-Master $119/540

^ SuperSort I 5199/540

v* SuperSort II S169/S40

^ SuperSort III S119/S40

PEACHTREE'W

General Ledger $399/540

Acct Receivable 5399/540

Acct Payable $399/$40

Payroll $399/$40

Inventory $399/$40

Property Mgt $799/540

C.PA Client Write-up. $799/540 Mailing Address ... S349/S40 STRUCTURED SYSTEMS

GLorARorAP# $747/$25

Payroll* $747/$ 25

Inventory Control* . . .$447/$40

Analyst* $197/$20

Letteright# $167/520

NAD# $ 87/520

QSORT $ 87/$20

GRAHAM-DORIANH

General Ledger* $693/$40

Acct Receivable* ... . $693/$40

Acct Payable* $693/540

Job Costing* $693/540

Payroll* $493/$40

Inventory* .$493/$40

Cash Register* $493/$40

Apartment Mgt* $493/540

MICRO-AP

Selector III-C2* $269/$20

Selector IV* $469/535

x- S-Basic $269/525

WHITESMITHS

"C" Compiler* $600/530

Pascal (incl "C") • $750/545

EIDOS SYSTEMS

Kiss $299/$25

K-Basic. $529/550

ORGANIC SOFTWARE

TextWriter III $111/$20

DateBook $269/$25

SoHo Group

^ MatchMaker .

^ Worksheet.

"OTHER GOODIES"

Tiny C" $ 89/$50

x" Tiny C" Compiler $229/550

CBASIC-2 $ 89/$15

Pascal/Z. $369/$30

s All 4

SUPERSOFT

Forth (8080 or Z80) $129/$25

Diagnostic I $ 49/$20

Other disk software ... less 10%

SOFTWARE WORKS

Adapt $ 69/ na

Ratfor $ 86/ na

COMPUTER PATHWAYS

Pearl (level 1)* $ 99/$25

s Pearl (level 2)# $299/540

i^ Pearl (level 3)* . ,. 5549/565

COMPLETE BUSINESS

SYSTEMS}

^Creator $269/525

• Reporter $169/$20

v* Both $399/$45

MICROPRO x- WordStar $324/$60

Mail/Merge $114/525

* — Special Bonus with »rder J —Requires microsoft BASIC H-Supplied in source code #-Requires CBASIC-2 & — Mfgs Traderr

ORDERS ONLY-CALL TOLL FREE VISA- MASTERCHARGE

1-800-854-2003 ext. 823 • Calif. 1-800-522-1500 ext. 823

add $10 plus additional postage • Add $2 50 postage and handling per each item

$ 97/$20 $177/$20

Pascal/UCSD . $299/$30

Pascal/MT+ $224/$30

Pascal/M $149/$20

NevadaCobol $129/525

x- Raid $229/$25

x- MAGSAM III $129/$25

x- MAGSAM IV $259/$25

x- BSTAM $129/$ 10

FMS-80 $649/545

dBASE II DBMS $629/$50

Condor DBMS . . $599/$30

Vulcan DBMS $469/530

T.I.M. DBMS*. $329/$35

CBS $369/$45

Whatsit? $149/$25

x- Ultra-Sort II $159/525

x- MicroStat $224/$15

String/80 $ 84/$20

x- Vedit. S 99/$ 15

Postmaster $ 149/$20

WordSearch $179/$25

SpellGuard $269/525

Spell Binder $349/$45

x- VTS/80 $489/$65

Magic Wand $299/$45

Electric Pencil II less 15%

CPAids iess 12%

APPLE II

MICROSOFT

Softcard (CP/M) $292

Cobol 5574

PERSONAL SOFTWARE

Visicalc- 5122

CCA Data Mgr ... $ 84

Desktop/Plan $ 84

x* Zork. $ 34

PEACHTREEMlt

General Ledger $224/$40

Acct Receivable $224/$40

Acct Payable $224/$40

Payroll. $224/$40

Inventory $224/$40

MUSE

Super-Text II $127

Other disk software. . less 10% STC (Software Tech.) x-Prof Time 8. Billing $279 Other less 15%

OTHER GOODIES"

x* Data Factory $129

Whatsit?- $129

x-Creator $229

x* LedgerPlus

(GL A/R & A/P) $549

TRS-SO- MODEL II

CP/M 2.2 (P8.T) $159/535

Electric Pencil II less 15%

NORTHSTAR

x- NorthWord. 5299

x» Mail Manager $239

x- Info Manager $369

x* General Ledger $749

x* Acct Receivable $449

x- Acct Payable .$449

Overseas

residents add 6% sales tax • Allow 2 weeks on checks. CO D ok

All items subject to availability

California Prices subject to change without notice

THE DISCOUNT SOFTWARE GROUP

1610 Argyle Ave., Bldg. 102 • Los Angeles, CA90028 • (213)666-7677

been designed for the fastgrowing Saudi Arabian business community. Pavilions by the United States, the United Kingdom, West Germany, France, Italy, and approximately fifteen other countries will be featured. For more information, contact Donald Ryan, Project Manager, Rm 3200, US Department of Commerce, Washington DC 20230, (202) 377-4652.

May 1981

May Z

National Computer Problem-Solving Contest for Junior and Senior High School Students, throughout the US. Small teams of junior and senior high school students will compete for two hours on computer systems to solve five programming problems. Winners will be judged on whether their programs run properly using the test data supplied in the problem, are easy to read, logical, imaginative, and creative.

To receive a copy of the 1981 contest problems, local school directors should contact the University of Wisconsin—Parkside by April 4. Directors must agree to keep the problems confidential until the day of the contest. After that, any organization can use the problems to conduct their own contest. Local contest winners can enter the national and international contest. A national and worldwide ranking will be determined by a team of judges from the University of Wisconsin—Parkside. All interested schools or organizations can share the 1981 contest problems.

For additional information, write Dr Donald T Piele, Associate Professor of Mathematics, University of Wisconsin—Parkside, Kenosha WI 53141.

May 4-7

National Computer Conference, McCormick PI, Chicago IL. Approximately 90,000 people are expected

312 March 1981 © BYTE Publications Inc

Circle 231 on inquiry card.

to attend the National Computer Conference (NCC) this year. The use of robots and artificial intelligence will be among the program sessions at the Personal-Computing Festival during the NCC. For the first time, personalcomputing exhibits will join the rest of the conference in the main exhibit area. Over thirty technical sessions will be held. All major companies will be represented. Contact the American Federation of Information Processing Societies Inc, POB 9658, 1815 N Lynn St, Arlington VA 22209, (703) 558-3617.

May 11-13

The Thirty-First Electronic Components Conference,

Colony Square Hotel, Atlanta GA. Papers on semiconductor-processing technology, optoelectronic devices, manufacturing technology, materials, hybrid microcircuits, discrete components, interconnections, reliability, and connectors will be read. Contact T G Grau, Bell Laboratories, Whippany Rd, Rm 3B-312, Whippany NJ 07981; or Electronics Industries Association, 2001 Eye St NW, Washington DC 20006.

May 14-16

The Tenth ASIS Mid-Year Meeting, Fort Lewis College, Durango CO. The American Society for Information Science's (ASIS) theme for this meeting is "Using Information." Among the topics to be addressed are user studies, decision making, organizational change, government, education, management, access to information, and designing information systems for use. For information, contact ASIS, 1010 16th St NW, Washington DC 20036, (202) 659-3644.

May 17-20

Expo '81, Loew's Anatole Hotel, Dallas TX. Expo '81 is a combination of exhibits and technical sessions. The exhibits cover everything from graphics systems to industrial computer-control systems. The technical ses

CPU's &

SUPPORT

CHIPS

aoaoA

8085A

AMD 2901

8205

8212

8216

B226

8228

8251

8259

8257IAM9517I

Z80A SID - 17.95

8275 - 16.95

FD1791 -3-1.95

RAM'S

4116 3

41162

21L023

2102-4

MK4027-3

MK4096 II

TMS404S-25

MS40SONL

2101 1

21 078)5280

MM5270

MK4008P

ROM's

«001 - 25

4027

Jti?H 3 029 4030 4034 ■JO::")

- .45 4053

4072

10)6

tan

4516 4518 4520 4553 74 CM 74C02 74C04

74CDH

74C20 74C32 74C73

.25 74C76

75 74CB3

175 74CB5 - '

95 74C86

75 74C9Q

75 74C93

1 95 74C151

1.95 74C157 - I

74C163 71CI65 74C173

UART's

AY5 1013 - 3.75

TFH602II - 3.95

AY3-8500 - 1.95

PT14S2B -3 25

INTERFACE & DRIVERS

14BS - 90

1489 - 1.25

B130 - 2.50

8131 - 2.50

6830 - 2.50

6833 - 2.50

6834 - 2.00 8B37 - 2.00 8B3S - 2.00 8T380 - 2.00

2516

253?

6223

82523

82S112

825115

82S123

825126

825129

82S130

82S131

AM9218C

- 29 95

- 3.95

- 2.95

-2.95

- 3.25

- 3.45

- 3.95

SHIFT REGISTERS

MM1402 MM1403 MM1404 MM5013 MM50I6 MM505S MM5056 MM5057 MM5D58 MM5060

PRINTED CIRCUIT BOARD

4" x 6" DOUBLE SIDED

LEADER OSCILLOSCOPES

WE CARRY A FULL LINE OF HIGH

QUALITY, LOW PRICED

OSCILLOSCOPES WITH A TWO YEAR

WARRANTY. COMPARE PRICE

& FEATURES.

LB0517 50 MHz D.T. CAL

DELAY $1950.00

SO-302

BO-308S

3-310A

J507A

3 508A -J 5 V. 3 513

OSCILLOSCOPES 10 MHi.D.T.,3" Compact 20 MHz, D.T . 3" PO'iaule

4MHI.S.T. Rocui Sweti 20MHi. ST.. 5" 20 MHi. D T.,510 MHt, ST.. 5" . 10 MHj, S T. ImV Sens. IOMHi, O T.. lmVSens.

1 790 00 950.00 275.00

495 00 . 645 00 1.530 00 1,100 00

SPECIALS GOOD THRU MARCH 1981

8" DISKETTES HARD SECTOR $1.75,10/516.00

74S00 74S02 74S04 74S05 74S08 74S11 74S15 74S20

74S30 74S32 74S80

74S80 74S112 74S133 74S140 74S153

.40 74S151

.40 74S157

.60 74S158

.90 74S174

.85 74S257

.40 74S25B

.00 74S374

7 WATT LD 65 LASER DIODE IR $8.95

25 wan Infra Red Pulse ISG 2006 equiv.)

Laser Diode (Spec sheet included)

S24.95

2N3S20 P FET $ .45

2N 5457 N FET $ .45

2N2646 UJT S .45

ER 900 TRIGGER DIODES 4/51.00

2N 6028 PROG. UJT 5 .65

TTL REED RELAY - SPST5V20ma $1.00

CLOCK CHIPS

MM5387AA 55.95

MM5314 64.75

MM5316.. $4.95

TANTALUM CAPACITORS

.22UF35V 5/51.00 10UF 10U "s -40

.47UF 35 V 5/51.00 22UF 10V -5 .30

.68UF35V 5/51.00 15UF 16V 3/S1.00

1UF35V 5/51.00 30UF 6V 5/S1 00

2.2UF20V 551.00 33UF 20V 5 .60

3.3UF20V 4/51.00 100UF15V $ .70

4.7UF15V 5/51.00 " " * „

6.8UF35V 3/51.00 150UF15V $ -95

SAIMKEN

AUDIO POWER AMPS

SM010G10WATTS .. $ 7.50 Si 1020 G 20 WATTS .. $11.00 Si 1050 G 50 WATTS .. $25.00 Si 1030 G 30 WATTS. . $13.50

200 PRV 1A LASCR .95

RS232

CONNECTORS

DB25Pmale $3.25

DB25Sfemale ... $4.25 HOODS $1.50

CRYSTALS $3.45 ea.

2.000MH* 6.144MHz

3.000MHz ID.OOOMHj 18.000 MHi 18.432 MHz 20.000 MHi

RIBBON CABLE

FLATICOLOR CODED)

#30WIRE

16cond. - ,40/per lool 40cond. - .75/peifoot 50cond. - .90/per fool

MINIATURE MULTI-TURN TRIM POTS 100.5K, 10K, 20K.250K. ... S.75 each .

NO. 30 WIRE WRAP WIRE SINGLE STRAND

100' 51.40

.LCO MINIATURE TOGGLE SWITCHES

MTA 106 SPOT SI.05

MTA206DPDT S1.70

MTA206P-DPDTCENTROFF 91.85

MSD206PDPDT CENTER OFF LEVER SWITCH SI 85

SCR's

1.5A

6A

35A

110A

100

.45

.60

1.40

?m

.70

an

1.90

9.00

400

1.20

1.40

2.60

12.00

600

1.80

3.60

15.00

TRIAC's

PRV

100

1A

.45

10A

.80

2SA

1.55

200

,!14

1 .HO

2.10

400 600

1.30 2.00

1.90 2.75

3.10 4.30

FP 100 PHOTO TRANS $ .50

RED, YELLOW OR GEEN LARGE LED's. .2" 6/S1.00

RED/GREEN BIPOLAR LED's. S .55

MLED92 R LED S .75

MRD14B PHOTO DARL. XTOR 5 .75

TIL-118 0PTO-ISOLATOR. S .75

IL-50PTO ISOLATOR S .80

1 WATT ZENERS: 3.3.4.7.5.1, 5.6.6.8.8.2,9.1. 10.

12, 15. 18, or 22V 6IS1.00

SFC 3301 - 50 PRV 30A FAST RECOVERY DIODE (35ns) .

$2.25

SILICON POWER RECTIFIERS

PRV

1A

3A

12A

50A

125A

240A

100

.06

.14

.35

.90

.3.70

5.00

200

.07

.20

.40

1.30

4.25

6.50

400

.09

.25

.65

1.50

6.50

9.60

600

.11

.30

.80

2.00

8.50

12.50

SOO

15

.35

1.00

2.50

10.50

16.50

~45 T25 3^00 12.50 20.00

IN4148IIN914). 15/$1.00

.lor .01 u(25V ceramic disc, capts. 16/51.00, 100/55.00

LED READOUTS

FCS 8024-4 digit C.C. 8" display FND503C.C..5" FND 510 C.A. .5" DL-704-.3" C.C. FND 359 L.A. DL-707C.A. .3" DL 747 C.A. .6" HP3400 .8" CA HP3405 .8" CC

$5.95 S .85 S .85 S .85 S .60 $ .75 $1.50 $1.95 $1.95

f -ill iMiilM -■■ TRANSISTOR SPECIALS

2N1303PNPGETO5 . ...

2N1307PNPGCTOS

2N404APNPGMO-5 .. -. 3'S1.00

HEPG6014 - PNPGETO 3 ... S .85

TIP121 - NPNSiSWITCHING ., ..» 35

2N6233 NPN SWITCHING POWER. S1.95

MRF-8004 aCBRFTBANSISTQRNPN. .9 .75

2N3772 NPN SiTO-3. .. SI 00

2N49Q8 PNPSiTO-3. .... 51.00

2N50B6PNPSiTO92 . . 4fS1.00

2N3137NPNSiRF. . . -S .55

2N3919NPN S.T03RF .. .91.50

2N1420NPN Si TO 5 3:91.00

2N3767NPN SiTO-66 S .70

2N2222NPN SiTO 18 .SiSLOO

2N2907 NPN SiTO IB . . .... 4/S1.00

2N305SNPNSiTO3... . .. .5.60

2N3904 NPN Si TO 92 ... 6/91.00

2N3906PNPSiTO92 .. 6JS1.00

2N5236NPNSiTO220 . 2N6109PNPS. TO 220. T1P31BNPNSiTO 220 TIP32BPNPS. TO 220 TlP34PNPSi

7ALS113 - 45

74LSI1A - 55

741.S123 - 75

74LSI25 - 90

7ALSI26 - .90

74LS132 - 60

74LS136 - 80

74LS138 - 75

741S240- 160 74LS24I - 1.60 741.S212 - 1 60 74LS2M- 160 74LS244 - 1 60 74LS245 -2 35 74I.S251 - 1.29 74LS2S3- 1 00 74LS2S? - .90 74LS25B- 90 74LS259 - 1 50 741.S266 - 70 74LS273- 125 74LS279 - .70

74t_S290 - ea

74LS293 - .80 74LS365 - B0 74LS366 74LS36774LS36874LS3J3 74LS375 74LS377- 1. 74LS3&674LS333- 1

LINEAR CIRCUITS

3 - 59 i07 - 30 308-75

LM553 - 2.25

LF355 LI356

LM3I1 LM318

1 25

- 1.35

- 1 $0

- .75

- I.J0

LM3177

LM337

323H5V3A

79HGKC 5Vai5A

REGULATORS

LM1310 - 1.95 LM1B0B - 1.75 LMI810 - 220 LMI889 - 1.95 CA758 - I 75 CA301B- 1.95 CA3MB - 85 CA307B - 1.50 C A 3080 - .95 CA3086 - .35 CA30M - 2.25 NEW0L - 2.50 8038CC - 390 M5596A - 1.50

LM305G 3«0K 12.1 340T 5, 6.

112 . 12V3A 53 95

POSTAGE ADO 10% FOR ORDERS UNDER 520.00 RATES ADD 5% FOR ORDERS BETWEEN $20.00 AND $50.00

ADD 3% FOR ORDERS ABOVE $50.00

TERMS: FOB CAMBRIDGE. MASS. SEND CHECK OR MONEY ORDER. MINIMUM TELEPHONE, C.O.D. PURCHASE ORDER OR CHARGE $2000 MINIMUM MAIL ORDER 55.00.

SEND 5.25 FOR OUR CATALOG FEATURING TRANSISTORS & RECTIFIERS. 145 HAMPSHIRE ST.. CAMBRIDGE. MASS. 02139

SOLID STATE SALES

P.O.BOX74B

SOMERVILLE, MASS. 02143

g TEL. (617)547-7053

WE SHIP OVER 95c/</ OF OUR ORDERS THE DAY WE RECEIVE THEM

TOLL FREE 1-800-343-5230

Circle 232 on Inquiry card.

March 1981 © BYTE Publications Inc 313

CALL TOLL FREE

800-538-5000

CALL US FOR VOLUME QUOTES. ALL MERCHANDISE 100% GUARANTEED. WE WILL BEAT ANY COMPETITORS PRICES. GIVE US A CALL AND WE'LL PROVE IT.

NEC UPD416C-2 [2716-SINGLESUPPLY "

4116-200NS m95EA

8/9.95ea

8/29.95 100/3.45ea J^2708 6.25ea

8/5.95ea

2114L-3 4K STATIC ¥ 21 L02 L«^er

1.29ea

LOW POWER 300 NS

8/29.95 100/3.49ea I 2102

450NS

.99ea

LS SERIES LOOK AT THIS LS PRICING!

74LS00 .32 74LS73 .44 74LS156 .95

74LS251

1.32

74LS01 .28 74LS74 .48 74LS157 .79

74LS253

.89

74LS02 .38 74LS75 .58 74LS158 .82

74LS257

.89

74LS03 .32 74LS76 .50 74LS160 .94

74LS258

.89

74LS04 .35 74LS78 .59 74LS161 .99

74LS259

2.89

74LS05 .28 74LS83 .90 74LS162 .99

74LS260

.68

74LS08 .38 74LS85 1.23 74LS163 .99

74LS266

.68

74LS09 .38 74LS86 .45 74LS164 .99

74LS273

1.69 I

74LS10 .32 74LS90 .70 74LS165 .99

74LS275

3.39

74LS11 .29 74LS92 .82 74LS166 2.40

74LS279

.59

74LS12 .29 74LS93 .71 74LS168 1.79

74LS283

1.03

74LS13 .38 74LS95 1.11 74LS169 1.79

74LS290

1.25

74LS14 .99 74LS96 .86 74LS170 1.89

74LS293

1.89

74LS15 .35 74LS107 .43 74LS173 .82

74LS295

1.09

74LS20 .26 74LS109 .49 74LS174 1.19

74LS298

1.24

74LS21 .30 74LS112 .48 74LS175 1.09

74LS352

1.59

74LS22 .34 74LS113 .48 74LS1B1 2.19

74LS353

1.59

74LS26 .40 74LS114 .55 74LS190 1.15

74LS363

1.39 !,

74LS27 .35 74LS122 .55 74LS191 1.31

74LS365

.99 I:

74LS28 .39 74LS123 .99 74LS192 .88

74LS366

.99

74LS30 .35 74LS125 .99 74LS193 .98

74LS367

.99

74LS32 .39 74LS126 .88 74LS194 1.80

74LS368

.99

74LS33 .54 74LS132 .69 74LS195 1.39

74LS373

1.85

74LS37 .78 74LS136 .58 74LS196 .82

74LS374

1.81

74LS38 .39 74LS138 .79 74LS197 .82

74LS377

1.48

74LS40 .25 74LS139 .79 74LS221 1.28

74LS385

1.90

74LS42 .79 74LS145 1.19 74LS240 1.89

74LS386

.65

74LS47 .78 74LS148 1.39 74LS241 1.89

74LS390

1.90

74LS48 .78 74LS151 .79 74LS242 1.89

74LS393

1.90

74LS51 .35 74LS153 .79 74LS243 1.89

74LS395

1.69

74LS54 .35 74LS154 2.39 74LS244 1.79

74LS670

2.20

74LS55 .32 74LS155 1.19 74LS245 2.89

,

8080 SUPPORT |

M1SC

EPROMS

Ay5-1013 4.99

MM5203AQ 1us

256x8 13.95

8212 2.75

8T97 1.69

MM5204AQ 750ns

512x8 14.95

8214 5.25

1488 1.39

1702A 1us

256x8 4.95

8216 2.75

1489 1.39

2708 450ns

1Kx8 5.95

8224 2.95

8202 34.95

2716 450ns

2Kx8 10.95

8226 3.49 8228 4.95 8238 5.50

3242 16.95

2732 450ns

4K X 8 29.95

PROMS

8251 6.95 !

8253 12.95 ;

74S18B (82S23) OC

32 X

8 4.75

8255 6.50

74S2B7 (82S129) TS

256 X 4 4.75 i

8257 16.95

74S288 (82S123) TS

32 X

8 4.75

8259 14.95

74S387 (82S126) OC

256x4 5.75

8275 49.95

74S471 TS

256 X

8 18.75

8279 15.95

74S472 (82S147) TS

512x

8 18.75

74S474 (82S141) TS

512 X

8 19.95

74S570 (82S130) OC

512x4 7.80

CPU's

74S571 (82S131) TS

512x4 7.80

Z-80 9-95

DIP SWITCHES

LINEAR

Z-B0A 12.95

8080A 3.95 4 Position .99 7 Position 1.09

LM30IV

.34 LM567V1.29

8085A 12.95 I 5 Position 1.02 8 Position 1.14

LM309K1.49 LM723 .49

26

50 12.95 6 Position 1.06

LM311V .64 LM741V .29 LM317T 2.29 LM747 .79

, VOLTAGE REG'S

IC SOCKETS

LM323K4.95 LM1310 1.90 LM324 tn ' **•**'** 1 En

43"LED DISPLAY ■ 7812T 89 7912T "

.'iJ LCU UIOrLHT 7815T 99 7915T , 19

8 PIN 10/1.29 14 PIN 10/1.49 16 PIN 10/1.69

LM339 LM377

.j3 i_ivi i«t it i,«ia

.99 LM1458 .69

2.29 LM1488 1.39

BEAUTIFUL RED ! ™24T -99 ?924T 1.19

7 SEGMENT DISPLAY 1 7805K 1-39 7905K 1"9 i acumcNi uiorLMT« 7812K 1 39 7912k 1.49

18 PIN 10/1.99 20 PIN 10/2.89 22 PIN 10/2.99

LM380

LM555V

LM556

1.29 LM1489 1.39 .39 LM1800 1.99 .69 LM1889 2.49

HP 5082-7760 ! 78L05 .69 79L05 .79

24 PIN 10/2.99

LM565

.99 LM3900 .59

.79 100/.65EA1 78L12 .69 79L12 .79

28 PIN 10/3.99

LM566Vl.4a fc.4c.iv .jy

^ ^^L. 78L15 .69 79L15 ..79

40 PIN 10/4.99

JE

■

VISA*

TERMS: In- j

IR MICRODEVICES, INC.

elude! shippi

2 lor ! lg. $10 '

master charge

1101 South Winchester Blvd. "I""l"",u'

P^w^^J

San Jose, California 95128 Send SASfc for 1 inn v/n »ao complete catalog. Be

y Ar

ja Res. add

6v2% sales tax

408-247-4852 Calif Res add 6% sa,es ,

800-538-5000 niinntilipa anii auhclif nip

ix. We rese

rve the right to limit rer. Prices subject Id

www www www ijuallllllG9 aim autlatliuit'

TidmiliMilti

sions range from tool design, design engineering, and robotics to numerical control. For more information, contact the Numerical Control Society, 519 Zenith Dr, Glenview IL 60025, (312) 297-5010.

May 26-29

The Second Annual Korea International Office Management Exhibition and Conference, Korea Exhibition Center, Seoul, Korea. American, British, Japanese, and Korean exhibitors will attend this conference. Exhibits include computers, facsimile systems, copiers, duplicators, micrographics, and other office equipment and products. Write to Clapp & Poliak, International, 7315 Wisconsin Ave, Washington DC 20014, (301) 657-3090.■

BYTE's Bits

Missing References In Circuit Cellar

Three references were inadvertently omitted from Steve Ciarcia's Circuit Cellar article "Electromagnetic Interference" (January 1981 BYTE, page 48). The following books provide additional reading material for those interested in the topic:

1. Ott, Henry W. Noise Reduction Techniques in Electronic Systems. New York: John Wiley & Sons, 1976.

2. Jones, R W. Electric Control Systems. New York: John Wiley & Sons, 1953.

3. Shadowitz, Albert. Electromagnetic Field. New York: McGraw-Hill Book Company, 1974.

Noise Reduction Techniques in Electronic Systems was reviewed by J N Demas in the September 1980 BYTE, page 311. ■

314

March 1981 © BYTE Publications Inc

Circle 233 on Inquiry card.

Clubs and Newsletters

Atari Club Newsletter

Each month the Atari Computer Enthusiasts News contains news, hints, and assistance for Atari owners and users. Most of the information is supplied by club members, but articles from all interested Atari users are welcomed. Contact the Atari Computer Enthusiasts, 3662 Vine Maple Dr, Eugene OR 97405.

TSUNAMI

The Sorcerer Users Newsletter Around Michigan (TSUNAMI) is a free, bimonthly newsletter for Exidy Sorcerer owners. The editorial focus is on advanced applications in a variety of languages. Recent issues have featured a 7-generation per second Life program and a Paper Tiger screen-printer program. Contact Joseph R Power, 124 Cedar St #5, East Lansing MI 48823, (517) 337-1049.

MENTAT

MENTAT is a brand-new publication probing professional and recreational uses of computers, plus fantasy and role-playing designs, games, and simulations. MENTAT is an Amateur Press Association member. If you are interested in contributing, send a selfaddressed, stamped envelope to Bill Seligman, 667 Rugby Rd, Brooklyn NY 11230.

CPT Users Group Formed

An independent group for CPT word-processing system users has been formed. A quarterly newsletter covering word- and data-processing techniques and applications is published. The newsletter features a pro

gramming and problem clearinghouse, application notes, program reviews, a directory of software and support packages, and general-interest items. The group is not affiliated with the CPT Corporation. Contact Larry Matthews, c/o APB Inc, 919 Lindy Ct, Dayton OH 45415, (513) 890-9593.

Boston Computer Update

The Boston Computer Update is a bimonthly publication from the Boston Computer Society. It is free when you join the society; membership fees are $15 per year. Articles, news reports, and story ideas are welcomed. Members can place

free classified ads for noncommercial items. For further details, contact the society at 3 Center Plz, Boston MA 02108, (617) 227-9178.■

YOU THINK YOU'VE SEEN WORD PROCESSING SOFTWARE?

The

MAGfc WAND "v

Word Processing

System offers you the best features of any system

in the miCrO market Version 1.1 is now available

FEATURES INCLUDE: Full-screen text editor

Simple, control key operation Edit programs as well as text

Assemble, compile or run programs

without modification Files larger than memory

Files up to 256K Library files

Merge part or all of one file with

another Spool printing

Print a file while editing another Easy page formatting

Simple commands set margins, page

length, etc. Override commands at run-time

Give any command from the keyboard as well as in file Variable pitch control

Change pitch in mid-line, even

mid-word Up to 128 user-defined variables

String, numeric or dollar format Form letter generation from external data files

Compatible with both sequential and

fixed-record files Conditional commands

Any command may be conditional Print to disk and/or printer

Save all or part of output on disk Switch from specialty printer to CP/M list device

Print the same file on either specialty

or standard printer

EASE OF OPERATION

With all its power, the MAGIC WAND is remarkably easy to use. This is no accident. The command structure is designed to be flexible and logical so that you can perform basic functions with a minimum of commands.

We have included in the manual a stepby-step instructional program, for the person who has never used a word-processor before. The trainee uses sample files from the system disk and compares his work to simulated screens and printouts.

In addition to the lessons, the manual has a complete documentation of the command structure, special notesfor programmers, an introduction to CP/M for non-programmers and a glossary. The manual is typeset, rather than typewritten, for greater legibility.

We have written the manual in nontechnical English, because we want you to read it. We don't overload you with a bunch of jargon that could confuse even a PhD in Computer Sciences.

We send out newsletters so that users of the MAGIC WAND can learn special applications of the print commands. For example, we might show you how to create a mailing list or set up an index for a file.

In short, we've done everything we can to make thingseasy for you. Because the best software in the world is just a bunch of code if you can't use it.

For more information, call or write:

srcioW business applications, inc.

3220 Louisiana • Suite 205

Houston, Texas 77006

CP'W,...,

713-528-5158

giSWied ir.iciem.uk ot Digiui Res,

Circle 234 on inquiry card.

March 1981 © BYTE Publications Inc 315

BYTE's Bits

Photo 1: Personal computers can give the handicapped access to everyday activities. Here, a Johns Hopkins engineer demonstrates typing on a computer-aid electronic keyboard activated by a chin controller. The Johns Hopkins National Search for Applications of Personal Computing to Aid the Handicapped hopes to uncover similar applications.

All Printer Interface Cables $35.00

(Call for all cable needs)

RS232 CABLES

Male to Male 9' long $24.00

Male to Male 18' long $29.00

Male to Female 9' long $29.00

Male to Female 18' long $34.00

Female to Female 9' long $34.00

Female to Female 18' long $39.00

Male to Open 9' long $18.00

Male to Open 18' long $23.00

Female to Open 9' long $24.00

Female to Open 18' long $29.00 26 Pin Card-edge Connector

to DB25S 18" long $19.00 26 Socket Type Connector

to DB25S 4' long $19.00

Power Cable Kit for Disk Drives comes with AC & DC plug and wire $10.00

Call for prices on all types of connectors

DISK DRIVE SIGNAL CABLES

Single 5%" Drive Cable $24.00

Dual 5W' Drive Cable $29.00

Quad bVt" Drive Cable $34.00

Single 8" Drive Cable $24.00

Dual 8" Drive Cable $32.00

Quad 8" Drive Cable $40.00

Please state type connector: card-edge or socket.

4116 (200 ns)

- 8/$30.00

2708 —

$6.00

2716 (5V) —

$9.00

2732 —

$25.00

2114L3 —

8/$28.00

LAX COMPUTER PRODUCTS

4728 Manhattan Beach Blvd. Lawndale, CA 90260 (213) 542-4505

WE ACCEPT VISA,

MASTER CHARGE AND

AMERICAN EXPRESS

National Search to Aid the Handicapped Through Personal Computers

Johns Hopkins University has announced a national search for ideas and inventions using personal computers and related technology to assist the handicapped. The National Science Foundation and the Radio Shack Division of the Tandy Corporation are cosponsoring the search.

The competition seeks ideas, devices, methods, and computer programs to help handicapped people overcome learning disabilities, employment difficulties, and barriers that prevent adapting to home and community settings. Categories that can be addressed include computer-based aids for the blind, deaf, and mentally retarded; for individuals with learning disabilities, neurological or neuromuscular conditions; and the orthopedically handicapped. One hundred awards will be made, including a $10,000 grand prize, and other prizes consisting of computer equipment and cash. Proceedings describing the winning entries will be published at the end of the contest. All participants will retain commercial rights to their entries.

Entries are being sought from computer specialists, high school and college students, and from all interested people. Orientation meetings are being scheduled at rehabilitation centers throughout the US to bring together potential inventors, handicapped individuals, and professionals in the habilitation/rehabilitation fields.

Contestants must prepare and submit their entries by June 30, 1981. To obtain additional information and a contest application, BYTE urges you to write to Personal Computing to Aid the Handicapped, Johns Hopkins University, POB 670, Laurel MD 20810, (301) 953-7100. ■

316

March 1981 © BYTE Publications Inc

Circle 235 on Inquiry card.

Computer Music: A Design Tutorial

The computational power necessary to synthesize high-quality, polyphonic computer music in real time exceeds the resources of the currently available microprocessors. Despite this discouraging observation, I decided early in the fall of 1978 to design a microprocessor-based music synthesizer. My goal was to discover just how successful I would be with a minimum system constructed from readily available parts. My self-imposed design constraints included an avoidance of special-purpose hardwired logic and an intention to stick with a byte-oriented architecture.

I hesitate to call the results of my efforts a music synthesizer. A more honest description might be a program-controlled, digital tone generator. Specifically, the design generates a predetermined sequence of sinusoidal waveforms in the manner of a player piano. A binary musical score or command program specifies the pitch and duration of each note. Each instruction in the command program selects between approximately 30,000 possible pitches from 0.1 Hz to 3 kHz, and selects between 255 possible dura

About the Author

Tom Orlofsky is an employee of Bell Telephone Laboratories Inc. He works in systems engineering. His hobbies, in addition to application of home computers to music, include tennis, hiking, and skiing.

Thomas P Orlofsky

8 Victoria Dr Eatontown NJ 07724

tions from 10 ms to 2.55 seconds. This relatively fine time and frequency resolution permits quite sophisticated melodic articulations such as the slur, glissando, and vibrato. While the design provides memory for 341 notes or rests, this limitation is by no means essential.

I will begin by discussing the frequency-synthesis method before diving into a more detailed description of the implementation in both hardware and software. Along the way, you will become familiar with the engineering trade-offs inherent in the design of a digital sound system. At the conclusion, some possible improvements and points of departure for your own experiments will be discussed.

Frequency-Synthesis Method

Frequency synthesis is the process of generating an output frequency bearing a mathematical relationship to some reference frequency. Digital synthesis differs from analog synthesis in that the waveform is constructed from a mathematical process rather than from modification of the energy storage of a physical system. Since the digital method is mathe

matical, the quality of the output signal is theoretically unlimited. In practice, however, the transformation from samples to smoothly changing voltages introduces noise that is independent of the precision of the mathematical calculation.

Figure 1 illustrates the method of digital-frequency synthesis used in the design. A complete sine wave is divided into 256 segments. The average amplitude of each segment is measured with 8-bit precision. These measurements, or samples, are stored in consecutive memory locations. Each sample specifies the amplitude of the waveform at a particular phase angle. Consequently, the address of a sample is equivalent to its phase. One way to vary the frequency of the constructed waveform is by varying the rate at which the samples are selected. However, a more practical procedure maintains a constant sampling rate and varies the phase increment between the samples. A larger phase increment has the effect of skipping some of the samples during a pass through the memory.

Observe that the phase of the current sample being selected is formed from the sum of the phase increment and the phase of the previous sample. Only the nine most significant bits of the phase register actually contribute to the address of the current sample. The addition of the phase and phase increment is performed modulo 216, and the overflow is equivalent to a

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Circle 236 on inquiry card.

March 1981 © BYTE Publications Inc 317

.FOR THE APPLE

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PHASE INCREMENT REGISTER

6.5536 k

H, O

>16

U

L2.

16 BIT ADDER

^T

5406 Roblee Dr., Upper Marlboro. MD 20870

PHASE ACCUMULATOR

16-C

LL

ROUNDING

>8

ADDRESS

LA

256x8 SAMPLES

MEMORY

SIN

k = 0,l,..,255

DATA

n

D

SAMPLES TO

DIGITAL-TO-ANALOG

CONVERTER

Figure 1: Conceptual block diagram of the frequency-synthesis method. This scheme will produce one of 32,768 unique frequencies.

phase shift of — 2ir.

As an illustrative exercise, assume a phase increment of 256, and that the addition is performed at a rate of 6.5536 kHz. Under these circumstances, the resultant set of addresses will select every sample once per cycle and produce a constructed waveform of frequency equal to (6.5536 kHz / 256) or 25.6 Hz. Now assume a phase increment of 257. In each cycle through the memory, one sample is skipped. However, one particular sample is skipped only once in 257 cycles. This shows that the second phase increment increases the frequency of the constructed waveform in such a way that the second waveform will complete 257 cycles in the time that the first completed 256 cycles. The new frequency is (6.5536 kHz X 257) / (256 X 256) or 25.7 Hz. This particular choice of sampling rate and register size provides a con

venient frequency resolution of 0.1 Hz.

It is crucial to observe that the sampling rate is fixed and that the amplitude envelope of the selected samples determines the frequency of the constructed waveform. In other words, the average period of the constructed waveform is not constrained to be an integer multiple of the sampling period. This result of sampling theory follows from the elegant properties of sine waves in the frequency domain. Sampling theory also shows that perfect construction of the sine wave is theoretically possible with as few as two samples per cycle.

Critical Design Considerations

At this point, we judge that the sampling rate is by far the most critical design parameter. Increasing

Text continued on page 320

318 March 1981 © BYTE Publications lnc

Photo 1: The author's microprocessor computer music system implemented in a breadboard prototype suitcase. A 2Vi-inch speaker (lower left) provides audio output for demonstrations. Best results were obtained by patching into the power amplifier of a highfidelity receiver.

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March 1981 © BYTE Publications Inc 319

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Text continued from page 318:

the sampling rate increases the audio bandwidth, but the sampling rate is limited by the rate at which the microprocessor system can deliver samples to the output port.

The method of waveform construction adds considerations to the issue of the sampling rate beyond those already mentioned. A digital-toanalog (D/A) converter transforms the samples into discrete voltage levels producing a sine wave with a staircase appearance. A low-pass filter smooths over the discontinuities by removing the so-called sampling harmonics. Unfortunately, a practical filter passes some of the sampling harmonics due to finite attenuation of frequency components in the rejection band. Therefore, the design must sacrifice some of the theoretical bandwidth of the synthesizer to achieve tones that are relatively free of audible distortion. The magnitude of the sacrifice is, of course, a function of your sensitivity to harmonic distortion. If you are to judge harmonic distortion by the advertised specifications of high-fidelity audio equipment, it is quite undesirable.

My choice of sampling at a rate of 6.5536 kHz represents-a compromise. On one hand, the 150 microseconds or so of calculation time allows the microprocessor to execute a nontrivial program, yet the audio bandwidth encompasses the range of the fundamental frequency of most musical instruments. However, on the other hand, much of the bandwidth contains audible harmonic distortion.

Another important design consideration concerns the necessary precision and quantity of the stored samples. The difference between the stored value of a sample and the actual value of the sine function evaluated at the same phase introduces an error into the constructed waveform. This disturbance is known as quantization noise. The quantization noise associated with 256 8-bit samples has an average power that is about one percent of the average power of the sine wave. Therefore, in this particular design, the noise due to quantization is quite inaudible in comparison with the sampling harmonics that sneak through the filter.

Finally, the design must exhibit sufficient resolution between frequencies. You may have noticed in the il

320 March 1981 © BYTE Publications Inc

Circle 238 on inquiry card.

lustrative example that the length of the phase accumulator determined the smallest possible frequency increment. Resolution of 0.1 Hz provides the potential of arbitrary tuning. Two tones 0.1 Hz apart in frequency played simultaneously beat together once every 10 seconds. Such mistuning is imperceptible under normal conditions. Another aspect is the granularity of pitch changes during a glissando. While 0.1 Hz might be sufficient for the casual listener, the granularity is audible under close scrutiny. Unfortunately, increased resolution for fixed-register length is purchased with decreased audio bandwidth, and the bandwidth cannot be spared.

Hardware

Now that the problems facing the designer are in perspective, the hardware design will be described so that you may digest the schematic diagram. Figure 2 provides an overview of the system implementation; figure 3 is the schematic diagram. The hardware is functionally divided between the microprocessor system and the analog signal conditioning. In addition to the Z80 processor, the microprocessor system includes 2 K bytes of erasable programmable read-only memory (EPROM) and two input/output (I/O) devices. An 8212 8-bit I/O port, hardwired into a simple output latch, serves as an interface to the D/A converter. A Z80 counter-timer circuit provides interval timing. The system includes no general-purpose programmable memory. The processor and countertimer circuit serve as depositories for all dynamic information. A simple crystal oscillator generates the system clock signal, and a momentary push button allows the system to be reset. Sufficient device-select logic insures that two devices cannot be simultaneously enabled, regardless of the state of the machine. Finally, the system requires well-regulated external power supplies of +5, +12, and -12 V.

Although the 6 kHz sampling rate is quite demanding from the computational point of view, the rate is quite modest with respect to state-ofthe-art conversion speeds. An inexpensive D/A converter such as the MC1408 proves to be quite sufficient. The active low-pass filter is a secondorder Butterworth-type with a cutoff

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Circle 239 on inquiry card.

March 1981 © BYTE Publications Inc 321

Circle 240 on inquiry card.

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at approximately 3 kHz. If you are interested in maximum tone purity, use a higher-order filter design. The filter output appropriately buffered and attenuated can be patched into the power amplifier section of a typical home audio system. As usual, precautions should be taken to insure signal compatibility. You might want to use a blocking capacitor to trap the DC voltage present in the output during rests.

Software

Now with the hardware out of the

way, I can get down to the heart of system design, the software. The software is functionally divided between the system program and the command program. You can view the system program as a special-purpose operating system that not only performs the frequency synthesis, but also interprets the command program. The command program is essentially a musical score in a form understandable by the system program. Since the command program resides in its own memory device,

Text continued on page 324

Number

Type

+ 5V

GND

-12 V

+ 12 V

IC1

Z80-CPU

11

29

IC2

Z80-CTC

24

5

IC3

2708

24

12

19

IC4

2708

24

12

19

IC5

8212

24

12

IC6

74LS32

14

7

IC7

74LS74

14

7

IC8

74LS04

14

7

IC9

74LS04

14

7

IC10

MC1408

13

2

3

IC11

741

4

7

IC12

741

4

7

IC13

741

4

7

Power Wiring Table for Figure 3

FROM PUS

HBUTTON '

RESET

ZILOG Z80

CENTRAL PROCESSING UNIT

<*> T>

SYSTEM CLOCK

INTERRUPT

8 BIT

OUTPUT

LATCH

c

>n c

ni

$

ADDRESS BUS

0

ZILOG Z80

COUNTER

TIMER

CIRCUIT

L2.

^2.

2K BYTES ERASABLE PROGRAMMABLE READ-ONLY MEMORY

DIGITAL TO

ANALOG

CONVERTER

+ 2

CRYSTAL OSCILLATOR 3.2768 MHz

LOW PASS FILTER

POWER

AMPLIFIER

(EXTERNAL)

<l^ ^r

Figure 2: Functional overview of the hardware organization and signal flow.

322 March 1981 © BYTE Publications Inc

2 <

r^

S " ll

o o u

_J Q u.

-m—♦—^

t^

^ « ■CJ A. O ;* => O '

So_S^, 1 ,, Lfc -.

:n

Q Q Q Q Q Q Q

QQOOOQOQ <<<<

ra

OOOOOOOQ <<«<<<<*t<<

oqqq qqqqoIq

II ° u> > >

♦—wv >t>

Figure 3: Schematic diagram for the microprocessor-controlled music system. The design is self-contained except for power and the final audio-output stage. Efficient use of registers within the primary microprocessor eliminates the need for general-purpose memory.

March 1981 © BYTE Publications lnc 323

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No. 32

ESSEX PUBLISHING CO. oept 2 ^sg

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Order books by number. Send check, money order (U.S $), VISA or Master Charge ». Publisher pays 4th class shipping. For UPS shipping (USA onlyjadd $ 1.00 per book. For Air Mail shipping add $2.50 per book in North America, $5.00 in Europe and South America. $800 elsewhere N.J. residents add 5% sales tax. D No. 10 D No. 16 □ No. 32 D Check enclosed □ Credit card D 4th class □ UPS □ Air

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Hexadecimal Contents Address

System 0000 Program

Device IC4

03FF Command 0400 Program

IC3

07FF

08FF

Nonexistent

FFFF

Table 1: Memory map for of listings 1 and 2.

the software

Text continued from page 322:

you can play a new song by simply substituting one memory chip for another.

Figure 4 provides the algorithmic flow of the system program. Upon reset, the system program initializes registers within the Z80 processor and counter-timer circuit, reads the first command, calculates the first sample, and halts. The remainder of the program, contained entirely within one interrupt-service routine, executes once per sampling period in response to interrupt requests from the counter-timer circuit. As the samples are generated, the counter-timer circuit clicks them off in a down counter. The processor polls the down counter during every sampling period and branches to the new-tone procedure when the counter reaches zero. The new-tone procedure fetches the next command and updates the registers accordingly. When the newtone procedure reaches an end of file, it performs an unconditional branch to the beginning of the command program.

Three bytes make up a command. The system program loads the first byte, the note duration, into the down counter within the countertimer circuit. Bytes 2 and 3 contain the pitch information or phase increment. Observe that a phase increment with a value of zero results in a stream of constant samples, a DC signal or rest.

324 March 1981 © BYTE Publications Inc

Circle 241 on inquiry card.

Hexadecimal Address

Device

00

Counter-Timer

Circuit (CTC)

03

04

Nonexistent

7F 80 81

8212 Latch

Nonexistent

f'f

Table 2: I/O port of figure 3.

map of the hardware

In general, the system program completes the sample calculation with time to spare. However, during the command fetch, the processor delays acknowledgment of the next sample interrupt for a fraction of the sampling period. Basically, the processor steals some extra time for housekeeping. Fortunately, the postponement of one sample among thousands is inaudible. If you are familiar with the Z80, then you should have minimal difficulty in deciphering the details of the system program provided in listing 1.

The command program example shown in listing 2 performs the measure of music pictured in figure 5. A macroassembler facilitates generation of the command program. Userdefined symbols for notes of the equally tempered scale (see text box) and common note durations eliminate the need to edit numbers. A note macroinstruction, which defines the data structure, reduces each command to a single line of code. The programmer can generate the command program quite efficiently by defining nested macroinstructions that specify repeated rhythms or articulations. Nevertheless, the process is quite tedious..

You may wonder why it is necessary to use sixteen bits to distinguish between twenty-four or so pitch symbols. The answer is that it is not strictly necessary, but.immense tonal flexibility can be gained. First of all, you can specify the sliding-note effects mentioned earlier. Second, you are not locked into the equally

Text continued on page 331

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March 1981 © BYTE Publications Inc 325

Circle 243 on inquiry card.

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( START J

INITIALIZE POINTERS WITHIN PROCESSOR AND COUNTER TIMER CIRCUIT(CTC)

SET UP FIRST NOTE FROM COMMAND PROGRAM

&

OUTPUT SAMPLE TO DIGITAL TO ANALOG CONVERTER

POLL TIMER (CTC) FOR CURRENT COUNT

HAS CURRENT NOTE FINISHED r— PLAYING

J

CALCULATE NEXT SAMPLE

YES

SET UP NEXT NOTE FROM COMMAND PROGRAM

I 1

I IS MELODY |_ I FINISHED |

I J

RESET COMMAND PROGRAM COUNTER (DEVICE NOW READY TO REPLAY TUNE)

YES

PROGRAM COUNTER TIMER CIRCUIT WITH NEW DURATION

LOAD PHASE INCREMENT REGISTER WITH NEW INCREMENT

ADVANCE COMMAND PROGRAM COUNTER

CALCULATE NEXT SAMPLE

Figure 4: Flowchart of the system program. The system program, executed in real time, performs the frequency synthesis and interprets the binary musical score contained in the command program.

326

March 1981 © BITE Publications Inc

Listing 1: The system program written in Z80 assembly language. See comment lines for details.

(0003) (0002) (0000) (0000) (0080)

0000 0000 0003 0007 0009 000B 000D OOOF 001 1 0014

210000

DD210004

3E01

ED47

3E00

D300

ED5E

310002

3E57

0002 0003 0004 0005 0006 0007 0008 0009 0010 001 1 0012 0013 0014 0015 0016 0017 0018 0019 0020 0021 0022 0023 0024 0025 0026 0027 0028 0029 0030 0031 0032 0033 0034 0035 0036 0037 0038 0039 004 1 0042 0043 0044 0045 0046 0047 0048 0049 0050 0051 0052 0053 0054 0Q55 0056 0057 0058 0059 0060 0061 0062 0063 0064 0065 0066 0067 0068 0070 0071 0072 0073 0074 0075 0076 0077 0078 0079 0080 0081 0082 0083 0084

****************************************************

TONE SYNTHESIZER SYSTEM PROGRAM

THI CESSOR SYS 2K PROM, 8 AND ANALOG RESIDES t SINUSOIDAL AND DURATI THE COMMAN OF MEMORY. TIONS PROV

INT THE SYSTEM ARE USED T POLLS CH3

PROG

TEM CO

212 US

SIGNA

N THE

SAMPL ON OF D PROG

THE

IDED B

ERRUPT

PROG

0 TIME

FOR A

RAM IS WRITTEN NSISTING OF A Z ED AS AN OUTPUT L CONDITIONING. FIRST IK OF MEM ES AT APPROX. 6 EACH SINUSIOD 0 RAM WHICH RESID SYSTEM PROGRAM Y THE COMMAND P S FROM CHANNEL RAM. CHANNELS

TONE DURATION.

TIME OUT CONDI

FOR 80-CP

LATC

THI

ORY G

KHZ. R TON ES IN EXECU ROGRA 0 OF 2 & 3

THE TION.

WRITTEN BY TOM ORLOFSKY 12-8-78

A Z80 MICRPRO

U, Z80-CTC,

H, 8 BIT DAC,

S PROGRAM WHICH

ENERATES

THE PITCH E IS SELECTED BY

THE SECOND IK TES THE INSTRUCM SEQUENTIALLY. THE CTC DRIVE

OF THE CTC SYSTEM PROGRAM

REGISTER USE: HL: BC: DE: I X: AF' : A :

CTC CHANNEL V CHO:

CH2: CH3:

LIST

CONTAINS THE PHASE CONTAINS THE PHASE INCREMENT CONTAINS THE SAMPLE ADDRESS COMMAND PROGRAM COUNTER

CONTAINS THE CONTROL CODE FOR CTC CH3 CONTAINS THE NEXT SAMPLE WHEN THE CPU IS HALTED E: DETERMINES THE SAMPLING PERIOD (250 T CYCLES)

DEVIDE 3Y TEMPO SCALING FACTOR TIMES NOTE DURATION (CLOCKED BY CH2)

NOGEN

SUPPRESS PRINTING OF MACRO-EXPANSIONS ****************************************************

SYMBOL DEFINITION

**************************************************** CH3 . EQU 03H ;ADDRESS OF CTC CH3 CH2 EQU 02H ;ADDRESS OF CTC CH2 CHO EQU OOH ;ADDRESS OF CTC CHO BASE EQU OH ;DISPLACEMENT FOR IX REG ADD DAC EQU 80H ;ADDRESS OF DAC BUFFERED BY 8212

****************************************************

MACRO DEFINITION THE MACRO FACILITATES EDITING THE SAMPLES

****************************************************

DATA: MACRO II A, Hi , IIC , #D , #E , II? , IIG , IIH

DB «A

DB lit,

DB He

DB HO

DB II?

DB f F

DB IIG

DB IIH MEND ****************************************************

INITIALIZATION PROCEDURE

****************************************************

ORG OH

NIT: LD ML,OH ;INIT PHASE REGISTER

LD IX,40011 ;INIT COMMAND PROGRAM COUNTER

LD A, 1H ;INIT INTERRUPT REGISTER

LD I, A

LD A,OH ;LOAD CTC INTERRUPT VECTOR

OUT CHO,A

IM2 ;INTERRUPT MODE 2

LD SP.020OH;INIT SP TO FAKE STAK

LD A.57H ;INIT CTC CHANNEL 3

Listing 1 continued on page 328

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Listing 1 continued:

0085

***C0NTR0L WORD DESCRIPTION***

0086

BIT 7=0

INTERRUPT DISABLE

0087

6 = 1

COUNTER MODE

0088

5 = 0

DON'T CARE

0089

4 = 1

TRIGGER ON RISING EDGE

0090

3 = 0

DON'T CARE

0091

2 = 1

TIME CONSTANT FOLLOWS

0092

1 = 1

RESET CHANNEL

0093

0 = 1

CONTROL CHANNEL WRITE

0016

08

0094

EX

AF, AF'

SAVE CONTROL WORD

0017

DD7E00

0095

LD

A,(IX+BASE);FETCH FIRST DURATION

001A

08

0096

EX

AF.AF'

GET CONTROL WORD

00 IB

D30 3

0097

OUT

CH3.A

OUTPUT CONTROL WORD

001D

08

0098

EX

AF.AF'

SAVE CONTROL WORD

001E

D303

0099

OUT

CH3.A

OUTPUT TIME CONSTANT

0020

3E57

0100

LD

A, 57H

INIT CTC CH2 SAME

0101

EXCEPT FOR TIME CONSTANT

0022

D302

0 102

OUT

CH2, A

OUTPUT CONTROL WORD

0024

3E40

0103

LD

A.64D

TEMPO SCALING FACTOR

0026

D302

0104

OUT

CH2, A

OUTPUT TIME CONSTANT

0028

DD23

0 105

INC

IX

INCREMENT COMMAND PC

002A

DD4E00

0106

LD

C,(IX+BASE);INIT PHASE INC REG

002D

DD23

0107

INC

IX

INCREMENT COMMAND PC

002F

DD4600

0108

LD

B,(IX+BASE);MOST SIGNIFICANT BYTE

0032

DD23

0109

INC

IX

INCREMENT COMMAND PC

0034

110002

0110

LD

DE,200H

INIT SAMPLE ADDRESS REG

0037

3ED7

0111

LD

A.OD7H

INIT CTC CHO SAME AS CH3

0039

D300

0112

OUT

CHO, A

EXCEPT ENABLE INTERRUPTS

003B

3E7D

0113

LD

A,125D

AND DIFFERENT TIME CONSTANT

003D

D300

01 14

OUT

CHO, A

OUTPUT TIME CONSTANT

003F

1A

0115

LD

A,(DE)

LOAD A WITH FIRST SAMPLE

0040

FB

0 116

EI

ENABLE INTERRUPTS

0041

76

0117 HOLD: HALT

WAIT HERE FOR ALL INTERRUPTS

0119

****************************************************

0120

012 1

INTERRUPT SERVICE ROUTINE

0122

0123

****************************************************

0042

0124

ORG

lOOH

0100

0201

0125

DK

INTRPT

ADDRESS FOR INDIRECT JUMP

01 26

TO INTERRUPT SERVICE ROUTINE

0127

THE INTERRUPT VECTOR PRO

0128

VIDED BY THE CTC POINTS HERE

0102

D380

0129 INTRPT: OUT

DAC , A

OUTPUT SAMPLE TO DAC

0 104

09

0130

ADD

HL.BC

INCREMENT PHASE REK

0131

ROUND OFF UPPER 9 BITS OF

0132

PHASE REG TO 8 BITS AND

0133

USE THESE AS LOWER 8 BITS

01 34

OF SAMPLE ADDRESS

0 105

5C

0135

LD

E,H

0 106

CB7D

0136

BIT

7 ,L

IF 1 THEN ROUND UP

0 108

CA0C01

0137

JP

Z.NEXT

IF 0 THEN ROUND DOWN

010B

1C

0138

INC

E

ROUND UP

010C

DB03

0 139 t

EXT: IN

A.CH3

POLL CTC CHANNEL 3

0 10E

D601

0140

SUB

A, 1H

TEST FOR VALUE 1

0110

CA1701

014 1

JP

Z.NEW

1 MEANS CHANGE TO NEXT TONE

0113

1A

0 142

LD

A,(DE)

CONTINUE PRESENT TONE

0143

LOAD A WITH NEXT SAMPLE

0 1 14

FB

0144

EI

ENABLE INTERRUPTS

0115

ED4D

0145

RETI

RETURN FROM INTERRUPT

0146

***************nEXT TON

PROCEDURE******** ************

0117

DD7E00

0147 1

IEW: LD

A, (IX+BA!

E);FETCH NEW DURATION

01 1A

C600

0148

ADD

A,OH

TEST FOR VALUE 0

0 149

IF ZERO JUMP TO BEGINNING

0150

ELSE CONTINUE SONG

01 1C

C22601

0151 1

'EST: JP

NZ.ANOTH

I

01 IF

DD210004

0 152

LD

IX.400H

COMMAND PROGRAM STARTS 400H

0123

C31701

0153

JP

NEW

0126

08

0154 t

N0THR: EX

AF,AF'

LOAD CTC CH3 WITH NEW DURATION

0 127

D303

0155

OUT

CH3, A

OUTPUT CONTROL WORD

0129

08

0156

EX

A F,AF'

SAVE CONTROL WORD

0 12A

D303

0157

OUT

CH3, A

OUTPUT NEW TIME CONSTANT

01 2C

DD23

0158 0 159

INC

IX

INCREMENT COMMAND PC JPDATE PHASE INCREMENT REG

012E

DD4E00

0160

LD

C, (IX + BA

iE);FETCH LOWER BYTE

0131

DD23

0161

INC

IX

INCREMENT COMMAND PC

0133

DD4600

0162

LD

B, ( IX + BA

iE);FETCH UPPER BYTE

0 136

DD23

0163

INC

IX

INCREMENT COMMAND PC

0138

1A

0164 0165 0166 0167

LD

A,(DE)

LOAD A WITH NEXT SAMPLE (EW PITCH WILL BECOME SFFECTIVE ON THE NEXT >AMPLE

0139

FB

0168

EI

ENABLE INTERRUPTS

0 13A

ED4D

0169 0170 0171

RETI *************

**********

RETURN FROM INTERRUPT *******************************

0172

DEFINE Fi

iKE STAK

0173

0174

SINCE

THERE IS N(

) WRITABLE MEMORY THE CPU

0175

WILL NOT BE ABLE

TO STORE THE RETURN ADDRESS

0176

OF THE

INTERRUPT

:d instruction, it must be

0177

PROVIDED IN READ

ONLY MEMORY.

0178

328 March 1981 © BYTE Publications Inc

Listing 1 continued:

01 79

******************************************************

01 3C

0180

ORG

1FEH

0 IF E 4100

0181

DW

HOLD

;ADDRESS OF

THE HALT

0182

INSTRUCTION

0184

******************************************************

0185

0 186

SINUSOIDAL SAMPLES

0187

256 8 BIT SAMPLES OVER 360 DEGREES

0 188

PRINTING OF THE OBJECT CODE

IS SUPPRESSED

0189

NUMBERS

ARE LISTED IN DECIMAL.

01 90

0191

******************************************************

0200

0192

DATA

128D

131D,134D , 137D

141D

144D

1 47D

150D

0208

020 1

DATA

153D

1 56D,159D,162D

165D

168D

1 71D

1 74D

0210

02 10

DATA

1 7 7D

180D,183D,186D

188D

191D

1 94D

1 96D

0218

0219

DATA

199D

202D,204D,207D

209D

2 12D

214D

2 1 6D

0220

0228

DATA

2 1 9D

221D,223D,225D

227D

229D

231D

233D

0228

0237

DATA

234D

236D,238D,239D

241D

242D

244D

245D

0230

0246

DATA

246D

247D.249D,250D

250D

251D

252D

253D

0238

0255

DATA

254D

254D,255D,255D

255D

255D

255D

255D

0240

0264

DATA

255D

255D,255D,255D

255D

255D

255D

254D

0248

027 3

DATA

254D

253D,252D,2513

250D

250D

249D

247D

0250

0282

DATA

246D

245D,244D.242D

241D

239D

238D

2 36D

0258

0291

DATA

234D

233D,231D,229D

227D

225D

223D

221D

0260

0300

DATA

2 1 9D

216D,2 14D , 212D

209D

207D

2 0 4D.

202D

0268

0309

DATA

199D

196D, 194D , 1 9 ID

1 88D

186D

183D

1 80D

0270

0318

DATA

177D

174D,171D,168D

165D

162D

1 59D

1 56D

0278

0327

DATA

1 53D

150D, 147D, 144D

14 ID

137D

1 34D

1 3 ID

0280

0336

DATA

128D

125D, 122D , 119D

1 15D

1 12D

109D

1 06D

0288

0345

DATA

103D

100D.097D,094D

09 1 D

088D

085D

082D

0290

0354

DATA

079D

076D.073D ,070D

068D

065D

062D

060D

0298

0363

DATA

057D

054D,052D,049D

047D

044D

042D

040D

02A0

0372

DATA

037D

035D,033D,031D

029D

027D

025D

023D

02A8

0381

DATA

022D

020D.018D,0 17D

015D

014D

012D

011D

02B0

0390

1 DATA

0 10D

009D,007D,006D

006D

005D

004D

003D

0 2B8

0399

DATA

002D

002D,001D,001D

001D

OOOD

OOOD

OOOD

02C0

0408

DATA

000D

000D,000D,000D

001D

001D

001D

002D

02C8

04 1 7

DATA

002D

003D.004D,005D

006D

006D

007D

009D

02D0

0426

DATA

0 10D

011D,0 12D,014D

015D

0 17D

0 18D

020D

02D8

0435

DATA

022D

023D.025D,027D

029D

031D

033D

035D

02E0

0444

DATA

037D

040D,042D,044D

047D

049D

052D

054D

02E8

045 3

DATA

057D

060D,062D,065D

068D

070D

073D

076D

02F0

0462

DATA

079D

082D.085D,088D

091D

094D

097D

100D

02F8

047 1

DATA

103D

106D,109D, 1 1 2D

1 1 5D

1 19D

1 22D

1 25D

Listing 2: A command program example making use of a macroassembler. The score of this music is given in figure 5.

(0002) (0004) (0008) (0010) (0020) (0040)

0002 0003 0004 0005 0006 0007 0008 0009 0010 001 1 0012 0013 0014

00 15 0016

001 7 0018 0019 0020 0021 0022 0023 0024 0025 0026 0027 0028 0029 0030 0031 0032 0033 0034 0035 0036 0037 0038 0039

******************************************************

TONE SYNTHESIZER COMMAND PROGRAM EXAMPLE

WRITTEN BY TOM ORLOFSKY 12-8-78

A M S YST TION S YST AN U CONT 1H , 2 AND REST

TEMP

THE

SET

PER

WITH

MODI

SYST

****

THE COMMA USICAL SCORE EM PROGRAM.

AND CAN HAV EM PROGRAM I NCONDITIONAL AIN THE PITC

h, . . .,aoo

VALUE ZERO C

SYMBOLS F ERED SCALE A TRANSLATION AT A TEMPO 0 MINUTE. OTH EXPRESSION S FICATION OF EM PROGRAM. ************

ND PROGRAM IS A REPRESENTATION OF IN OBJECT CODE EXECUTABLE BY THE THE FIRST BYTE IS THE NOTE DURAE VALUE 2H,3H, . . . ,FFH. THE NTERPRETS A ZERO NOTE DURATION AS REPEAT. THE FOLLOWING TWO BYTES H INFORMATION AND CAN HAVE VALUE H. VALUES >800H CAUSE ALIASING AUSES A DC OUTPUT OR APPARENT

OR TWO OCTAVES OF THE EQUALLY

ND COMMON NOTE DURATIONS SIMPLIFY

PROCESS. THE NOTE DURATIONS ARE

F APPROXIMATELY 96 QUARTER NOTES

ER NOTE DURATIONS CAN BE CONSTRUCTED

OTHER TEMPOS REQUIRE THE TEMPO SCALING FACTOR IN THE

*************************************

*****************************************************

SYMBOL DEFINIT ION

*****************************************************

DEFINE NOTE DURATIONS

128 EQU 2D ;128TH NOTE

64 EQU 4D ;64TH NOTE

32 EQU 8D ;32ND NOTE

16 EQU 16D ;16THNOTE

8 EQU 32D ;8TH NOTE

4 EQU 64D JQUARTER NOTE

Listing 2 continued on page 330

Circle 245 on inquiry card.

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Circle 248 on inquiry card.

Listing 2 continued:

(0080) (0 100) (0000)

(0898) (091B) (091B) (09A5) (0A38) (0AD4) (0AD4) (OB79) C0C2 7) (OC27) (0CE0) (0DA4) (OE74) (OE74) (0F50) (1038) (!038) (1130) (1236) (1236) (134B) (1471) ( 1 5A8) ( 1 5A8) (16F1) (1 84F) (184F) (19C1) (1B49) ( 1CE8) (1CE8) ( 1EA0) (2072) (2072)

0000

0000

0000

40

000 1

7 114

0003

0003

04

0004

0000

0006

0006

3C

0007

7 114

0009

0009

04

0 0 0A

0000

oooc

oooc

3C

000D

7 1 14

000F

000F

20

0010

4B1 3

0012

00 12

20

0013

3011

0015

0015

20

0016

500F

0018

0018

20

00 19

A40D

00 IB

001B

40

00 1C

500F

001E

001E

20

001F

0000

0040 0041 0042 0043 0044 0045 0046 0047 0048 0049 0050 0051 0052 0053 0054 0055 0056 0057 0058 0059 0060 0061 0062 0063 0064 0065 0066 0067 0068 0069 0070 0071 0072 0073 0074 0075 0076 0077 0079 0080 0081 0082 0083 0084 D085 0086 0087 0088 0089 0090 0091 0092 0094 0095 0096 0097 0098 0099 0100 0101 0102

0103 +

0104 + 0105

0106 +

0107 + 0108

0109 +

0110 + 0111

0112 +

0113 + 01 14

0115 +

0116 + 0117

0118 +

0119 + 0120

0121 +

0122 + 0123

0124 +

0125 + 0126 0127+ 0128 + 0129

0130 +

0131 + 0132

0133 +

0134 +

. 2 . 1 REST

A0 1

AS01

BF01

B01

CO 1

CS01

DF0 1

D01

DS0 1

EF01

E0 1

F01

FS0 1

GF01

C01

GS0 1

AF01

A0

AS0

BF0

B0

CO

CSO

DF0

DO

DS0

EF0

E0

F0

FS0

GF0

GO

GS0

AF0

EQU EQU EQU

EQU EQU EQU EQU EQU EQU EQU EQU EQU EQU EQU EQU EQU EQU EQU EQU EQU EQU EQU EQU EQU EQU EQU EQU EQU EQU EQU EQU EQU EQU EQU EQU EQU EQU

128D 256D 0D

2200D

2331D

AS0 1

2469D

2616D

2 772D

CSO 1

2937D

31 1 ID

DS01

3296D

3492D

3^001)

FS01

3920D

4 152D

GS0 1

4400D

4662D

AS0

4939D

5233D

5544D

cso

58 73D

6223D

DS0

6593D

6985D

7400D

FS0

7840D

8306D

CSO

;I1ALF NOTE ;WH0LE NOTE

DEFINE P ITCHS

FORM XXNN

XX=L0CATI0N OF THE NOTE

WITHIN THE OCTAVE EXAMPLE: AF=A FLAT

;NN=L0CATI0N OF THE OCTAVE ;EXAMPLE: 0=0CTAVE ;C0NTAINING MIDDLE G ;EXAMPLE: 01=OCTAVE BELOW 0

;C0NVERT TO HZ. BY MULTIPLYING ;B Y 0.1 HZ .

***************************************************

MACRO DEFINITION

MACRO N (NOTE) FACILITATES EDITING OF COMMAND PROGRAMS AND DEFINES THF. DATA STRUCTURE

***************************************************

N: MACRO II TIME, //PITCH

DB //TIME

DW //PITCH

MEND ************************ * ***********************

COMMAND PROGRAM

TRANSLATION OF THE MEASURE OF FIGURE 5

************************************************ ORG on

N .4,CO

DB .4

DW CO

N .6 4,REST

DB .64

D W REST

N .4-.64,CO

DB .4 -.6 4

DW CO

\i . 6 4 , R E S T

DB .64

D W REST

N .4-.64,CO

DB .4-.6 4

DW CO

. 8, B0

DB DM

N

DB

DW

N

DB

DW

N

DB

DW

N

DB DW

0

8, A0

8 AO

8 ,G01

8

01

8.F01

8

0 1

4 ,G01

4

01

8,REST

3 REST

Listing 2 continued on page 331

Text continued from page 325:

tempered scale, but can experiment with other scale temperings. It is necessary to choose between the benefits of such flexibility and the value of considerable data compression possible in a table-lookup approach.

System Enhancements

Once you gain confidence in the methods of music synthesis, you may wish to add features or otherwise improve the system. For instance, you may decide to generate a second melodic line, or voice, using the system. Careful analysis of the instructionexecution cycles in the system described in this article show that sufficient computing time is available to generate a second voice.

The second voice may be synthesized along with the first, using the remaining registers in the control microprocessor and counter-timer microprocessor. As the last step in the synthesis, the separate samples should be summed and then scaled by a factor of 0.5.

Control of dynamics (amplitude) of the music is made possible by the addition of a programmable reference voltage for the signal converter. Four bits (a nybble) may be added to each note specification to select between sixteen possible dynamic levels.

If you are satisfied with the single voice, you may decide to improve the command interpreter instead. A good place to start is to add commands such as change tempo, branch conditionally, and halt.

If you are willing to try distributed processing, you can develop a command interpreter of practically unlimited capability. One microprocessor can be dedicated to the task of note synthesis, while another processor can handle the interpretation of commands and note specifications.

In a system that uses distributed processing, the command processor, unencumbered with calculations of samples, has time to execute complex routines during the intervals between processing of commands. A parallel

#1

uisr'iW

Listing

2 continued:

0021

0135

N

.8

CO

0021

20

0136 +

DB

.8

0022

7 114

0137 +

D'J

CO

0024

0138

N

.8

B0

0024

20

0139 +

DB

.8

0025

4B 13

0140 +

DW

B0

0027

0141

5

.8

CO

0027

20

0142 +

DB

.8

0028

7114

0143 +

DW

CO

002A

00

0144

DB

OH

002B

(0000)

0145

END

Errors

0

system architecture could enable more exact control over individual waveform samples. For example, a parallel processor could modulate the

signal on a sample-by-sample basis, creating attack and decay envelopes or frequency-modulated timbres. As new and more powerful micro

Figure 5: One measure that has been translated into the command program example provided in listing 2.

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Circle 249 on inquiry card.

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processors become available, those of us that synthesize music as a hobby will use them in our circuit designs. And since systems built for hobby use do not have to be compatible with any previous equipment, we are free to use the best ideas currently available.!

Use of equally tempered tuning makes it possible to play music in any diatonic scale on a keyboard instrument without having to change the tuning of the instrument. By international convention, the note A4 (second space on the treble clef) is defined to have the frequency of 440.0 Hz. Since raising a pitch by one octave is the same as doubling the frequency, we can calculate the frequency of A in any octave quite easily by multiplying and dividing by the appropriate power of 2.

In equally tempered tuning, the octave is divided into twelve notes; each pair of adjacent notes is separated by an interval called a semitone. The ratio of frequencies between the adjacent notes is equal to the twelfth root of 2, or

f,« / fk= 2'"2 Using these relationships, it is easy to calculate the frequency of any arbitrary note.

References Hillburn, J L and D E Johnson, Manual of Active Filter Design, McGraw-Hill Book Company, New York, 1973, pages 5 thru 52.

Osborne, A, J Kane, R Rector, and S Jacobson, Z80 Programming for Logic Design, Osborne/McGraw-Hil CA, 1978.

Snell, J, "Design of a Digital Which Will Generate Up to Distortion Sine Waves in Real Time," Computer Music Journal, April 1977, pages 4 thru 24.

Tierney, J, C M Rader, and B Gold, "A Digital Frequency Synthesizer," IEEE Transactions Audio and Electroacoustics, March 1971, pages 43 thru 57. Z80-CPU Technical Manual, Zilog Inc, Cupertino CA, 1977.

Z80 Counter Timer Circuit Technical Manual, Zilog Inc, Cupertino CA, 1977.

Berkeley

Oscillator 256 Low

332

March 1981 © BYTE Publications Inc

Circle 250 on inquiry card.

Programming Quickies

Constellation I: An Astronomy Program

Howard Berenbon, 2681 Peterboro, West Bloomfield M148033

Here is an educational program for those interested in astronomy. It displays ten of the most well-known constellations and gives a multiple-choice test to see if you've been paying attention.

Constellation I (see listing 1) is written in BASIC and will run on many computers, including the Radio Shack TRS-80 Model I Levels I and II and SwJPC 6800. It requires roughly 4 K bytes of memory.

Operation

After running the program, you can review the constellations by entering a 1. You can enter a 0 to take the test. If you choose to review the constellations (highly suggested before taking the test), enter another number from 1 thru 10. For each number entry, a constellation will be displayed using asterisks as stars, along with its name (see listing 2). The constellations may be reviewed in or out of sequence and for any length of time.

When you review the tenth constellation, you again have a choice of taking or not taking the test. Enter a 0 if you are ready. Otherwise, you can continue reviewing.

The test consists of ten multiple-choice questions. A constellation is displayed with four possible answers. Enter the number (1 thru 4) of the name that corresponds to the constellation. The program will advance to the

Text continued on page 335

Listing 1: Constellation I, a program for learning ten constellations. This program requires only 4 K bytes of memory and will run without modification in many BASIC systems.

5 PRINT'CONSTELLATIDN I"

10 PRINT'COPYRIGHT <C> 1979 BY HOWARD BERENB0N'

2 0 PRINT

30 PRINT'THIS PROGRAM DISPLAYS 10 CONSTELLATIONS AND■

35 PRINT'GIVES A MULTIPLE CHOICE TEST . ■

10 PRINT

15 FORI-1TO10

50 A(I)=0

5 5 NEXTI

100 INPUT'l-REUIEW, 0-TEST'iA

110 IFA-OTHEN3000

118 PRINT

;20 PRINT-ENTER *1-10"

125 INPUTE

130 ONBGDT02100r2130r2160r250 0,25 30,2540i260 Or 2630,2660r270 0

200 PRINT-CASSIOPEIA"

220

PRINTTAB<12>>

1 X"

230

PRINTTAB<26>;

■x"

210

PRINT' *

250

PRINTTA6(33>>

1 X"

260

RETURN

300

PRINT'LEO'

320

PRINTTAB(30>!

■ X '

330

PRINT"

310

PRINTTAB(23)i

' X ■

350

PRINT"

360

PRINT' *

370

RETURN

100

PRINT'URSA MAJOR

its

PRINTTAB(32> i

'X ■

120

PRINT

130

PRINT" X

110

PRINT "X

150

RETURN

500

PRINT'CEPHEUS

520

PRINTTAB(21 )!

■x ■

530

PRINT

510

PRINT"

X

550

PRINT

560

PRINTTAB<23>;

■x ■

570

PRINT"

530

PRINT

590

PRINT

600

PRINTTABI21);

■ X ■

610

RETURN

Listing 1 continued on page 334

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Circle 251 on inquiry card.

March 1981 © BYTE Publications Inc 333

Circle 252 on inquiry card.

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RETURN

211)0

GOSUBZ00

2110

GOTO 118

2130

GOSUB30 0

2110

G0T0118

2160

GOSUB100

2170

G0T0118

25 0 0

GOSUE:500

2510

G0T0118

2530

GOSUE:70 0

2510

G0T0118

2540

GOSUB8 0 0

2570

G0T0118

2600

GOSUB900

2610

G0TD118

2630

GOSUBJ.00 0

2410

G0TO118

2660

GOSU61200

2670

G070118

2700

GOSIJB1100

2710

G0T01IK)

3000

P=0

3010

PRINT-MULTIPLE CHOICE TEST*

K '

3020

PRINT'ENTER CORRECT ANSWER (tl

-1)

* *

3030 3010 3050

PRINT

PRINT'D"

GOSUB320

3060

PRINT'(1)

LEO

3070

PRINT"<2>

BOOTES"

3080

PRINT1(3)

LYRA"

3090

PRINT"(1)

LYNX"

3100

GOSUE50 5 0

3110

IFC=1G0SUE

5000!A<1>=10

3130

PRINT'2)■

3150

GOSUB52 0

3170

PRINT Ml)

PROCYON'

3180

PRINT"(2)

AURIGA"

3190

PRINT"(3)

CEPHEUS"

3200

PRINT"(1)

ORION"

3210

GOSUE5050

3220

IFC=3GOSUB5000!A<2>=10

3230

PRINT'3)"

3210

GOSUE1220

3260

PRINT"(1)

LEO"

3270

PRINT"(2)

AURIGA"

3280

PRINT"(3)

GEMINI

3290

PRINT"(1)

HYDRA"

3300

GOSUB5050

3310

IFC=2G0SU

:5000!A(3)=10

3320

PRINT'D"

3310

GOSUE720

Listing 1 continued:

700 PRINT'GEMINI"

720 PRINT" X

730 PRINT

710 PRINT

750 PRINTTABODi "X"

760 PRINT" >

770 PRINT

780 PRINT" *

790 PRINT" *

795 RETURN

BOO PRINT-CORONA BOREALIS"

820 PRINT"

830 PRINT" *

810 PRINT"

850 PRINT"

860 RETURN

900 PRINT-SAGITTARIUS"

920 PRINT" X

930 PRINT"

910 PRINTTAB(IZ)i"*■

950 PRINT

960 PRINT"

970 PRINT"

980 PRINT"

990 RETURN

1000 PRINT'LYRA"

1020 PRINT"

1030 PRINT"

1010 PRINT"

1060 PRINT

1070 PRINT"

1080 PRINT" X"

1090 RETURN

1200 PRINT'AURIGA"

1220 PRINT"

1230 PRINT"

1210 PRINT"

1250 PRINT

1260 PRINT" *

1270 PRINT"

1280 RETURN

1100 PRINT'CYGNUS"

1120 PRINT"

1130 PRINT"

1110 PRINT"

1150 PRINT" »

1170 PRINTTABC29);"X"

1180 PRINTTAB(32);"X"

1190 PRINTTABOS) i "X"

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334 March 1981 © BYTE Publications Ire

Circle 253 on inquiry card.

Circle 254 on Inquiry card.

Listing 1 continued:

3350

PRINT"(l) LEO"

3360

PRINT'CZ) CRUX"

3370

PRINT'(3) CANOPUS1

3380

PRINT'd) GEMINI1

3390

EOSUB5050

3100

IFC=1GOSUB5000SA(1>=10

3110

PRINT'S)1

3<I20

GOSU6220

3110

PRINT'd) AURIGA

3150

PRINT'(2) LYNX'

3140

PRINT'O) CASSIOPEIA'

3170

PRINT'd) LYRA'

3180

GOSUB5050

3190

IFC = 3GOSUE:5000!A(5) = 10

3500

PRINT"41"

3510

GOSUB820

3520

PRINT'd) LEO

3510

PRINT'(2) CYGNUS'

3560

PRINT'O) CORONA BOREALIS'

3570

PRINT'd) CEPHEUS'

3580

GOSLIB5050

3590

IFC = 3GOSUE:5000!A<6)=10

3400

PRINT'7) '

3610

GOSUB1020

3620

PRINT'd) LYRA'

3610

PRINT'(2> LEO'

3650

PRINT'O) ORION'

3660

PRINT'd) CETUS

3670

GOSUB5050

3680

IFC=1GOSUB5000!A(7)=10

3700

PRINT"B>'

3710

GOSUB920

3720

PRINT'd) CRUX'

3710

PRINT'(2) CETUS'

3750

PRINT'O) DRACO

3760

PRINT'(1) SAGITTARIUS'

3770

GOSUB5050

3780

IFC=1GOSUB5000!A(8)=10

3800

PRINT'9)'

3810

G0SUB115

3820

PRINT'd) LYRA'

3810

PRINT'(2) URSA MAJOR'

3850

PRINT'O) CRUX"

3860

PRINT'd) UIRGO"

3870

GOSUB5050

3880

IFC = 2GOSUE:5000:A(9) = 10

39 0 0

PRINT"lO)"

3910

GOSUB1120

3920

PRINT'd) CYGNUS'

3930

PRINT'(2) LEPUS'

3910

PRINT'O) PERSEUS

3950

PRINT'(1) TAURUS'

3960

GOSUB5D50

3970

IFC = 1GOSUE:5000:A<10) = 10

3980

PRINT

3985

PRINT'POINTS PER OUESTION'

3990

PRINT

1000

PRINT-1 = - iAd ) !■ 2 = ";A(2)i'

3=- iAO)

1010

PRINT'6='iA(6)i' 7='iA(7)i'

8=-iA<8>

1020

PRINT

1030

PRINT-SCORE IS JfMP

1010

END

5000

P = Pd0

5005

PRINT-CORRECT

5010

RETURN

5050

iNPUT-d-D ■ ;c

5060

RETURN

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i = -iA<i)i- 5=-;a<5> Listine3: Part of the ten-question test given by Constellation 1.

9=";A(9)»"10="JA(10)

The bottom part of the listing shows the points for each question and the final score.

1-REVIEW. 0-TEST? 0

MULTIPLE CHOICE TEST

ENTER CORRECT ANSWER (*1-1)

Listing 2: A sample run of Constellation 1 showing the review phase.

CASSIOPEIA

(1) LEO

(2) BOOTES

(3) LYRA <t> LYNX (1-1)? 1

ENTER * 1-10

POINTS PER QUESTION

1= 10 2 = 10 3= 10

6= 10 7= 10 B« 10

SCORE IS V. 100 READY

10 10

5= 10 10= 10

ENTER *1-10

10 CYGNUS

1-REVIEW. 0-TEST?

Text continued from page 333:

next question. After all questions are answered, a list of points per question is displayed along with your percent score (see listing 3).

You'll be surprised how much you have learned about the constellations. Next time you are stargazing, keep an eye out for Cassiopeia (it's near Andromeda). You won't have trouble recognizing it, if you have been doing your homework. ■

March 1981 © BYTE Publications Inc 335

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Seven data-shielding improvements mean greater durability and longer data life. These individually certified diskettes feature thicker oxide coating, longer-lasting lubricant, improved liner, superior polishing and more! Meets or exceeds IBM, Shugart, ANSI, ECMA and ISO standards. Buy the best ... buy DATALIFETM.

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10 boxes of 10 . . . (each box)$25.95

8-inch FLOPPIES

Single-Density, FD34-1000 $29.95 Double-Density, FD34 8000 $39.95

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TRS-80 is a TM ol Tandy Corp PLAIN JANE is a TM of MTC. M981 by Metatechnologies Corporation. Inc.

336

BYTE March 1981

Circle 255 on inquiry card.

What's New?

SYSTEMS

CMOS Processor from Motorola

8088-Based Board for the S-100

The CP88 is a 5 MHz 8088-based microprocessor board designed for the S-100-bus system. It features I -megabyte address space, 64 K I/O addresses, an instruction set with full 16-bit mathematics and extensive string-handling capabilities, a 3 K-byte EPROM, provision for 1 K bytes of programmable memory, memory addressing in the top 4 K bytes of address space, and the ability to disable memory space. The memory-access time is 450 ns. The CP88 has switchselectable 5 to 8 MHz clock rates and spare sockets for breadboarding. The CP88 is available as a bare board

only. It comes with documentation for S59.95 from Microfuture, POB 5951, San Jose CA 95150, |408) 249-0560.

Circle 401 on inquiry card

The MC146805E2 is an 8-bit CMOS microprocessor with a set of 61 instructions similar to the MC6800's. There's a set of bit-manipulation instructions to allow any bit in programmable memory or any I/O |input/output) line to be set or cleared with a single instruction. The device requires only 20 mW at 1 MHz and less than 1 mW in the standby mode. The supply-voltage range is 3 to 6 V DC. The unit includes an 8-bit timer with a software-programmable 7-bit prescaler, 112 bytes of programmable memory, and a clock generator. The multiplexed bus has an 8 K-byte addressing range. A 2 K-byte CMOS ROM is available. The processor is priced at S45 in unit quantities. Contact Motorola Semiconductor Products Inc. 3501 Ed Bluestein Blvd, Austin TX 7872 1.

Circle 400 on inquiry card

DTC's Microcomputer

The DTC Micro 210 contains 64 K bytes of programmable memory, a 2 K phantom ROM fread-only memory), an 8085A-2 microprocessor, and four RS-232C asynchronous interface ports. The unit employs two BASF 5-inch floppy-disk drives having 300 K bytes of storage. The operating systems available with the Micro 210 are compatible with DTC's other microcomputers. Single- and multiuser systems are available. Applications software can be written under CP/M, DTC's Multi-User Business BASIC, or DTC's version of Microsoft BASIC. The price for the Micro 210 is S3295 from DTC, 590 Division St, Campbell CA 95008, [408) 378-1112.

Circle 402 on inquiry card

Where Do New Products Items Come From?

The information printed in the new products pages of BYTE is obtained from "new product" or "press release" copy sent by the promoters of new products. If in our judgment the information might be of interestto the personal computing experimenters and homebrewers who read BYTE, we print it in some form. We openly solicit releases and photos from manufacturers and suppliers to this marketplace. The information is printed more or less as a first-in first-out queue, subject to occasional priority modifications. While we would not knowingly print untrue or inaccurate data, or data from unreliable companies, our capacity to evaluate the products and companies appearing in the "What's New?" feature is necessarily limited. We therefore cannot be responsible for product quality or company performance.

March 1981 © BYTE Publicalions Inc 337

What's New?

PERIPHERALS

Music Filter

The Music Sweetener is a low-pass filter designed to enhance Software Affair's Orchestra-80 and other commercial and homebrew D/A (digitalto-analog) converter music synthesizers that do not already have a filter. The unit attenuates the unwanted high-frequency sampling noise better than a stereo system's treble tone

-Music Sive«ener

control. It is designed for use in fourpart music synthesis on most microcomputers. The device is inserted between the music peripheral and the audio amplifier. The Music Sweetener is S39.95, plus S2 shipping, from Newtech Computer Systems Inc. 230 Clinton St, Brooklyn NY J1201, (212)

625-6220. Circle 403 on inquiry card

Apple II Printer

IMP2-Apple is an impact printer designed for the Apple II. It provides lowercase characters, single-command printer functions, and is compatible with the Pascal operating system. Priced at S895, the printer is equipped with friction and tractor feed to handle single sheets, roll paper, and fanfold forms. The unit can print 80, 96, or 132 columns at 1 line per second. The 7 by 7 dot matrix has a standard 96-character ASCII (American Standard Code for Information Interchange) set; special character sets are optional. IMP2Apple can handle user-defined and high-resolution graphics under software control. Contact Axiom Corporation, 5932 San Fernando Rd, Glendale CA 91 202, (213) 245-9244.

Circle 404 on inquiry card

Vision for Your Microcomputer

Microtex Corporation has developed an image-processing subsystem that allows microprocessors to be used in the gray-scale data acquisition from Reticon line-scan and matrix cameras. The Microtex 6400 device acquires 8-bit (256 gray level) data at I or 2.5 MHz, and provides all power, control, and clock signals to the Reticon camera. A board designed for the Digital Equipment Corporation LSI- ? 1 family of microprocessors, the 6400-A has a general-purpose interface for use with many other 16-bit microprocessors. An optional video processor will allow the user to see real-time data from the 256 by 256 matrix camera at approximately 30 frames per second.

The basic 6400 system includes the camera-control logic, an external synchronization input that initiates the scan, an 8-bit A/D (analog-to-digital) converter, 64 K bytes of programmable memory, and the Q-bus interface, which contains all the registers for software control of the subsystem. The 6400-A costs S4595 for the 1 MHz version and S4895 for the 2.5 MHz version. For more information, contact Microtex Corporation 80 Trowbridge St. Cambridge MA 02138, (617) 491-2874.

Circle 405 on inquiry card

»

■

'

■

Circuit-Board Holder

The Model 333 circuit-board holder from PanaVise Products Inc features an 8-position rotating adjustment, indexing at 45° increments, and 6 lock positions in the vertical plane, allowing a 10-inch height adjustment. With cross-bars available up to 30

inches in length, the holder can support circuit boards up to 28 inches wide. Extra arms can be added. It is built onto a pre-drilled cast-iron base for stability and easy mounting. Contact PanaVise Products Inc, 2850 E 29th St, Long Beach CA 90806, (213)

595-7621. Circle 406 on inquiry card

338 March 1981 © BYTE Publications Inc

What's New?

PERIPHERALS

40 and 60 W Switching DC Power Supplies

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I^^JjMk^ pi MaifMriM

Sierracin/Power Systems has developed a series of 40 and 60 W open-frame switching DC power supplies. The 5A and SB series, 40 and 60 W respectively, come in singleand multiple-output versions. The single-output models 5A5 and 5B5 deliver 5 V at 7 A and 12 A at full load. Prices for these models are S45 and S75 respectively. The 40 W multiple-output 5AXMP delivers 5 V at

4 A, ± 12 V at 0.5 A, -5 V at 0.5 A, and + 15 V at 1.0 A for S59. The 60 W multiple-output 5BXMP delivers

5 Vat 7 A, +12 Vat 1.5 A,-12 Vat 0.5 A, and -5 V at 0.25 A for S89. For complete details, contact Sierracin/ Power Systems, 20500 Plummer St, Chatsworth CA 91311, [800) 423-5569; in California (213) 998-9873.

Circle 412 on inquiry card

DIP-85 Printer

The DIP-85 impact printer features a 7 by 7 or 14 by 7 dot matrix, 6 character sizes, 100 cps (characters per second) bidirectional print speed, tractor or friction paper feed, and a ribbon cartridge. It has variable line density and continuous form-length controls. The printer has a high-resolution graphic capability and can provide plotting, video-display graphics, illustrations, and special-effects symbols. The unit has data rates up to 9600 bps, parallel and serial RS-232C ports, and a I K-byte buffer. With a 96-character ASCII (American Standard Code for Information Interchange! set. tne DIP-85 is capable of uppercase and lowercase printing at 80, 96, or 132 characters per line on standard-sized paper. Paper feed is at the rate of 10 lines per second. Operator control includes power, select/ deselect, line feed, top of form, selftest, and variable vertical-tab setting. The DIP-85 is priced at S625 in quantities of 100. For more information, contact DIP Inc. 745 Atlantic Ave, Boston MA 02111, (617) 482-4214.

Circle 413 on inquiry card

*%/>

T?

PRINTERS !! $499.00 Dip 81

(Friction Feed)

• 7x7 DOT MATRIX

mj\

•UPPER/LOWER CASE

g 11 ^§\ I

■BI-DIRECTIONAL PRINTING

■FAN COOLED -lOOc.p.s.

**

€ PROM PROGRAMMER

■ IEEE 696/S-100 CARD PROGRAMS 1K, 2K.4K, 48K PARTS

k 8 SOCKETS ACCEPT PROGRAMMED

...& MUCH MORE

EPROMS or RAMS

■ SWITCH SETTABLE: EXTENDED ADDRESS EXTENDED DEVICE SELECT

/S-100 KLUGE CARD

• ADDRESS BUFFERING-DATA BUS BUFFERING

■ CONTROL LOGIC ■ DEVICE SELECT ETC.

Other models available with tractor

feed, & other options. Write for

complete details. „■!» Ackerman Digital Systems, Inc. C312]530-8992

. y ■;. ■■■..-.■ DOS 110 N. York Rd., Suite 208, Elmhurst, III. 60126

Circle 256 on inquiry card.

March 1981 © BYTE Publications Inc 339

What's New?

PERIPHERALS

Idea Box for Experimenters

jg.- •■.g_i

The Idea Box combines three regulated, low-ripple power supplies; a choice of a solderless breadboard, a pre-etched, pre-drilled printed-circuit board, or a blank foil board. This combination allows easy construction of a prototype or a built-once-only device. The Idea Box is priced from S149.95. The circuit cards and printed-circuit

layout pads are available individually from S4.95 to S44.95. Contact Global Specialties Corporation, 70 Fulton Ter, New Haven CT 06509, [203) 624-3103.

Circle 407 on inquiry card

Interface the Apple II to

Centronics-Type Printers

The Model 7728 Centronics Printer Interface makes the Apple II compatible with printers using Centronicstype parallel interfaces, such as the Okidata Microline 80, the Microtek MT-80P, the MPI88T, and Centronics printers. A 256-byte ROM [read-only memory) provides driver firmware and controls character output to the printer. The 7728 supports the interrupt daisy chain with arbitration logic, including jumper-selectable IRQ gen

eration, and it provides direct-memory-access daisy-chain pass-through. The printer interface includes an 8-bit data output bus, four status inputs, data strobe and acknowledge handshake signals, and a printer-reset signal. The 7728 comes assembled and tested, with documentation, for S119.95. Cables for different printers are available from the manufacturer. Contact California Computer Systems, 250 Caribbean Dr, Sunnyvale CA 94086, (408) 734-5811.

Circle 408 on inquiry card

Five-Inch

Hard-Disk Drive

Tandon Magnetics Corporation has a family of hard-disk drives that can store 3.19 to 11.5 megabytes. The TM 600 family of 5-inch Winchester-type hard-disk drives contains one-, two-, and three-platter models. These drives feature a track-to-track access time of 3 ms and an average access time of 168 ms. Recording density is 7690 bits per inch and rotating speed is 3600 rpm (revolutions per minute). Tandon offers two interfaces, the S and the T versions. The S version is compatible with highercapacity drives, and the T version is compatible with Tandon's TM 100 floppy-disk drives. The T version allows the TM 600 series to run in a

daisy chain with the TM 100-4 floppy-disk drive. This permits 11.5 megabytes of fixed-disk storage in a daisy chain with 3 megabytes of floppydisk storage.

The three-platter TM 603E offers a capacity of 11.5 unformatted megabytes with 230 cylinders. The TM 602E is a two-platter unit offering 7.66 megabytes of storage with 230 cylinders. The two-platter TM 602 model stores 6.38 megabytes, and the TM 603 delivers 9.57 megabytes with three platters. Up to four TM 600s can be daisy-chained on a single bus. The TM 600 family is priced in the S1400 to S1600 range. Contact Tandon Magnetics Corporation, 9333 Oso Ave, Chatsworth CA 91311, (213) 993-6644.

Circle 409 on inquiry card

80 by 24 Video Display for the Apple II

The Full-View 80 is an 80-column by 24-line uppercase and lowercase plug-in video-display card for the Apple li. Under keyboard or program control, Full-View 80 permits user selection of 80- or 40-column graphics on the same monitor. Four character generators are offered. One is a 7 by 9 dot-character font. Two are userprogrammable EPROM (erasable programmable read-only memory) types that contain line-drawing graphics; one has 127 characters and the other 255 characters. The fourth is a 5 by 7 dot matrix to permit 80-column display on low-performance monitors. The Full-View 80 works with Apple Pascal, Microsoft's SoftCard, the Hayes Microcomputer Products Micromodem, the Apple Communications Card, and all Apple peripherals. A 2 K-byte ROM provides keyboard editing, cursor control, tabbing, and scrolling. Seven other keyboard-function keys are provided. The firmware incorporates Pascal and BASIC protocols. A real-time nonmaskable interrupt clock can be software-enabled to permit timing of programs in background mode. A read-screen capability, a blank-screen function, and a light-pen connector with firmware support are provided. When the keyboard is shift-locked, the cursor blinks. The price is S395 from Bit 3 Computer Corporation, 1890 Huron St, St Paul MN 551 13, (612) 926-6997.

Circle 410 on inquiry card

240 Ipm Thermal Printer/Plotter

Printer Systems Corporation's TH 240 is an 80-column thermal printer that prints 240 Ipm (lines per minute). This speed permits copying a 24-line video display in less than 6 seconds. The 240 has an optional plotting mode that produces 70 by 560 dots per inch resolution. The TH 240 is priced at S1395 for the alphanumeric version and S1595 for the alphanumeric-plus-plotting version. For details, contact Printer Systems Corporation, I W Deer Park Rd, Suite 104, Gaithersburg MD 20760. [301)

840-1070. Circle 411 on inquiry card

340 March 1981 © BYTE Publications lnc

What's New?

MISCELLANEOUS

Dual-Output DC Power Supplies

The 200 series dual-output DC power supplies from Power General include thirteen models with outputs of + 5 VDC, + 12 VDC, or ± 15 VDC with output currents from + 50 mA to + 500 mA. Other specifications include: input voltage range 105 to 125 VAC; input frequency 50 to 440 Hz; output-voltage accuracy ± 1%; line regulation +0.05%; load regulation ±0.1%; ripple and noise I mV RMS: transient recoveiy time 50 fis; breakdown voltage 1500 VAC; and an operating temperature range of -25°C to +71°C. Prices range from S49 to SI09. Contact Power General. 152 Will Dr, Canton MA 02021. [617] 828-6216.

Circle 417 on inquiry card

Let This Program Write Your Programs

PEARL Level 3 is an automatic systems generator. PEARL allows you to respond to on-screen menus and prompts to define a desired program. PEARL uses this input to generate error-free source code in BASIC and to produce desired applications software. It can also create complex multiple-file applications programs. The program lets you describe performance requirements, then turn the linear programming over to PEARL. PEARL 3 enables you to create programs for menu selection, file update and edit, reports, editing control data,

file reorganization, and general report writing. It can define and cross-index elements between multiple files within a single system, define reports using data from multiple files, extend the standard program menu, define the interrelationships between data elements in different files, postjournal files to a master file, provide extended report generation, and support multiple index keys for a file. PEARL 3 is priced at S650, PEARL 2 for S350, and PEARL I for S130. PEARL I and 2 are for beginning and intermediate programmers. Contact CPU, POB 12892, Salem OR 97309, [503) 370-8653.

Circle 418 on inquiry card

Mostek Announces a

64 K-Byte Dynamic Programmable Memory

The MK4164 is a series of 64 K-byte programmable memories featuring polysilicon lines instead of diffused bit lines for a 50% signal increase to the sense amplifier. By relocating the bit lines to a different level, the distance between adjacent capacitors is reduced to 3 microns. This space savings permits an increase of the storage-capacitor size to 75% of the total cell area. To increase the density from 16 to 64 K bits, the device uses

512 sense amplifiers. The MK4l64s feature an internal refresh counter. Another refresh feature permits the output to be held valid indefinitely by holding CAS (column address strobe) active low. The series features single + 5 V supply operation, maximum power of 300 mW [20 mW standby|, and 150 ns access time. The MK4164-15 has a 325 ns cycle time. The price for the MK4164-20 in 100-piece lots is S 59.99. For complete details on the MK4164s, contact Mostek Corporation, 1215 W Crosby Rd, Carrollton TX 75006, [214)

323-6000. Circle 419 on inquiry card

Built-in Foreign Languages

The ML-32 multi-language system offers users the ability to select sets of 32 different languages, resident in the system, and display these languages simultaneously on the screen or have them printed. The system offers multilanguage communications in a wordprocessing package. Black-and-white graphics are included with color graphics provided in the CML-32. The ML-32 can interface with any host computer system. The screen displays 34 lines of 80 characters on a highresolution monitor. There are 80 programmable function keys on the keyboard. The system can also utilize floppy-disk drives, cassette tape players, and hard-disk drives. RS232C, IEEE, and IBM 3270 input/output ports are provided. The languages in the system include English, Greek, Arabic, Hebrew, Russian, Japanese, Chinese, German, French, Italian, Welsh, Dutch, Norwegian, Swedish, Turkish, Spanish, Latin, Icelandic, Hungarian, Albanian, Bulgarian, and Portuguese. The price for the ML-32 is SI7,500, and the CML-32 is priced at $26,000. For more information, contact Michael Root at Computer Systems Consultants Inc, 225 Main St, Chelmsford MA01863, (617) 251-8561.

Circle 420 on inquiry card

March 1981 © BYTE Publications Inc 341

What's New?

MISCELLANEOUS

Hayden Books Brochure

Hayden Book Company Inc's new brochure lists books on computer science, electricity and electronics, engineering, mathematics, and other special interests. It is available free upon request from the Hayden Book Company Inc. 50 Essex St, Rochelle Park NJ 07662, (800) 827-3777, ext 302.

Circle 421 on inquiry card

Basic Electricity Course from Heathklt/Zenlth

The EE-3I00 Basic Electricity Course, from Heathkit/Zenith Educational Systems, is designed for the selfstarter. If you wish to expand your knowledge of basic electronics, this course will serve as your introduction to Ohm's Law, power, series and parallel circuits, electromagnetism, types of current, motors, generators, and meters. The course is written in a programmed-instruction format, and includes two audio cassettes. It is costs S29.95. Contact Heathkit/Zenith Educational Systems, Department 350-540. Benton Harbor Ml 49022. (616) 982-3210.

Circle 422 on inquiry card

Graphics Coprocessor Integrated Circuits

EFCIS, a subsidiary of ThomsonCSF, has introduced two graphics devices. The EF 9365 (512 by 512 pixels! and the EF 9366 (5 12 by 256 pixels! graphics processors can directly execute high-level-language descriptors by means of vector-descriptor files. The on-chip vector generator allows a writing speed of more than 500 meters per second on a 51 cm (21-inch) screen. The devices generate all the timing signals required for interfacing with video displays. The circuits contain a 96-character ASCII (American Standard Code for Information Interchange! generator. They also have light-pen registers and controls, three types of interrupt requests, and TTL-LS I/O ports. For additional details, contact EFCIS at 23, rue de Courcelles, B.P.96.08, 75362. Paris. Cedex 08, France.

Circle 423 on inquiry card

High-Speed 16 KByte

ROM Challenges

Bipolar PROMs

Synertek has announced the SY3316 MOS (metal-oxide semiconductor) 2048 by 8 high-speed ROM (read-only memoy) that can replace bipolar PROMs (programmable readonly memories) in many applications. The device features a maximum access time of 80 ns. It is fully compatible with 16 K-byte PROMs. The SY3316 is compatible with TTL (transistor-transistor logic) on all inputs and outputs and operates on a single + 5 V power supply. It includes three-state outputs. The device uses static circuitry and operates asynchronously. The three circuit-selects are mask programmable so that high, low, or undecided active states are possible. Eight ROMs can be connected without needing external decoding. In quantities of 250, the device is priced at S56. For more information, contact Synertek, 3001 Stender Way, Santa Clara CA 95051,

(408) 988-5623. Circle 424 on inquiry card

Intel's EEPROM

Intel Corporation has introduced an electrically erasable programmable read-only memory (EEPROM). The 2816 is a 16 K-bit nonvolatile memoiy that is byte-erasable with an access time of 250 ns. Users can erase, read, and write on the device without removing it from the computer. The 2816 erases and writes by causing electrons to tunnel across a thin layer of silicon dioxide. At 125°C, the 2816 will retain data for at least

20 years. The circuit is fully static and it needs no refreshing. Erasing and writing requires the application of a

21 V pulse for 10 ms. Any of the 2 K bytes of the 2816 can be erased and rewritten in 20 ms. Separate chipenable and output-enable pins permit 2-line control of the unit, which eliminates contention between addresses and data on multiplexed bus lines. It is pin-for-pin compatible with the 2716 ultraviolet EPROM and plug-compatible with 2732 and 2764 EPROMs. The 2816 costs SI20 in 100-piece lots. Contact Intel Corporation, 3065 Bowers Ave, Santa Clara CA 95051. (408) 987-6742.

Circle 425 on inquiry card

Color Computer

from Commodore

VIC 20 (video interface computer) is a color computer priced under S300. It connects to any television set or monitor and provides 5 K bytes of memoiy. VIC 20 features color, sound, programmable function keys, memory expansion to 32 K bytes, PET BASIC, expansion ports, a 22-character by 23-line screen display, highresolution graphics, graphics character set, joystick, paddles, light pen, and plug-in memory and program cartridges. VIC system peripherals include a cassette-tape drive, a floppydisk drive, and a printer. The computer uses the 6502 microprocessor and the VIC (video interface chip), which incorporates programmable memory, ROM (read-only memory), and video-control circuitry on the same integrated circuit. Contact Commodore Business Machines Inc. 950 Rittenhouse Rd, Norristown PA 19403, (215) 666-7950.

Circle 426 on inquiry card

Check Spelling with Spellguard

Spellguard is a program to check spelling in documents prepared with word processors and text editors. A 10,000-word document (20 pages) can be checked for spelling and typographical errors in under one minute. Spelling is checked using a dictionary supplied with the Spellguard package. The dictionary contains the 20,000 most-commonly used words in English and can be expanded. The dictionary size is limited only by disk-file size. One feature of Spellguard is the ability to create multiple dictionaries. Spellguard also contains a self-diagnostic feature for protection. Spellguard works with most CP/M-based word processors, including WordStar, Magic Wand, Electric Pencil, and Spellbinder. The program requires an 8080-, 8085A-, or Z80-based system, at least 32 K bytes of programmable memory, one 8-inch floppy-disk drive, and CP/M 1.4 or a later version. Spellguard has a suggested retail price of S295; a manual is available for S15. Contact Innovative Software Applications, 915 Timothy Ln, Menlo Park CA 94025, (415) 326-0805.

Circle 427 on inquiry card

342 March 1981 © BYTE Publications Inc

What's New?

SOFTWARE

UCSD Pascal for the Sprint 68

Wintek has the UCSD Pascal compiler available for its Sprint 68 microcomputer. The package includes an interactive operating system, Pascal compiler, screen-oriented editor, macroassembler, linker, p-code

interpreter, and a library of utilities. The price for the package is S675 from Wintek Corporation, 1801 South St, Lafayette IN 47905, |317) 742-8428.

Circle 429 on inquiry card

Duel-IU-Drolds

Duel-N-Droids is a sound and graphics game program for the TRS-80 Model I Level II. It features two sword-wielding androids that clash with each other in both practice and tournament duels. Each player controls his androids with four letter keys, causing it to maintain defense, back off, or attack. Each win moves the rank of the player's android up one level on the game scale. In practice duels, the player manually controls one android while the computer controls the other. In tournament duels, the machine controls both androids, using the skills instilled by the player during practice sessions. The program is priced at SI4.95 for cassette versions and S 20.95 on floppy disks. Contact Acorn Software Products Inc, 634 North Carolina Ave SE, Washington DC 20003, (202) 544-4259.

Circle 430 on inquiry card

Alpha Micro FIG-FORTH

Version 3.2 of /jA/FORTH is available for Alpha Micro systems. This version is aligned with the 1978 standard of the FORTH International Standards Team. It allows complete access to Alpha Micro's AMOS operating system. It implements full-length names up to 31 characters, checks code at compile-time with error reporting, and contains string-handling routines and a string-search editor. A FORTH assembler is included. FORTH words |commands) may be created from previously defined words, and even the original words supplied with the system can be redefined. It comes on an AMS format floppy disk and includes all source code, an editor, an assembler, and a string package. It costs S130 from Professional Management Services, 724 Arastradero Rd, Suite 109, Palo Alto CA 94306, |408) 252-2218.

Circle 431 on inquiry card

Apple II Curve Fitter

Curve Fitter allows you to select an appropriate mathematical curve to fit your experimental results. Methods include scaling and transformations, averaging, smoothing, interpolation, least-squares fitting, and interpolation of unknown values from the fitted curve. Using an optional A/D |analog-to-digital) converter, data can be entered directly from instruments. Curve Fitter is compatible with VisiChart. Curve Fitter runs on a 48 K-byte Apple II with Applesoft in ROM |read-only memory). It is available on floppy disk with a 29-page manual for S35. The manual is available separately for 55. Contact Paul K Warme, Interactive Microware Inc, POB 771. State College PA 16801, |8l4) 238-8294.

Circle 428 on inquiry card

UnlFLEX Operating System

UniFLEX is a multitasking, multiuser operating system. Several users can run different programs simultaneously, and one user can run several programs at a time. Users must log in with a password before being permitted to use the system. UniFLEX supports a hierarchical file system allowing file sizes up to I gigabyte |ie: I billion bytes) and disk capacities of over 8 gigabytes. All system I/O is device-independent. Any combination of interrupt-driven devices can be attached to the system. Intertask communication is supported, and task swapping can occur. The basic UniFLEX system includes the operating system, approximately 50 system utilities, a text editor, macroassembler, and system-configuration programs. System maintenance is also available. Software that runs under this system includes a C compiler, Pascal, word processors, a debug package, and BASIC. UniFLEX is available for 6809 and 68000 systems. The price is S450 for the 6809 version. Contact Technical Systems Consultants Inc, POB 2570, 1208 Kent Ave, West Lafayette IN 47906, |3l7) 463-2502.

Circle 432 on inquiry card

March 1981 © BYTE Publications Inc 343

What's New?

SOFTWARE

FORTRAN and COBOL

for the Apple II

with the SoftCard

The Apple II can now have FORTRAN and COBOL thanks to Microsoft Consumer Products. Both languages run under the CP/M operating system and are designed to be used with Microsoft's SoftCard. FORTRAN-80 can compile several hundred statements per minute in a single pass. The FORTRAN compiler creates true Z80 machine code and supports double-precision, integer X4 and integer XI data types. The FORTRAN-80 package includes the

compiler, a linking loader, and a user's manual. It also requires 48 K bytes of memory and a floppy-disk drive. The suggested price is S195.

COBOL-80 includes sequential, line-sequential, relative, and indexedsequential data files. Program chaining with parameter passing allows systems control from within COBOL applications. The program supports String, Unstring, Compute, Search, Perform, and Varying/Until verbs; abbreviated and compound conditions; ASCII (American Standard Code for Information Interchange], packed and binary data formats; run-time assignment of file names; full Copy

facility; and packed-decimal data format. The COBOL-80 package includes the compiler, linking loader, macroassembler, library manager, cross-reference assembler, and documentation. It runs on the Apple II with SoftCard, 48 K bytes of programmable memory, and two disk drives. The suggested price is S750. For complete details, contact Microsoft Consumer Products, 400 108th Ave NE, Suite 200, Bellevue WA 98004, (206) 454-1315.

Circle 433on inquiry card

Remote Batch Terminal Emulator

The Remote Batch Terminal Emulator, RBTE, allows Z80 systems to emulate an IBM 3780. 2780. 2770. 3741, or 2968 remote batch terminal. It provides the ability to transfer data files to and from mainframe computers or other remote batch terminals. Data rates up to 19.2 kbps (thousand bits per second) can be set. IBM bisynchronous protocol, hardware diagnostics, dynamic terminal configuration, on-line communication trace, attended and unattended operation, and user-customization are featured. The RBTE runs under CP/M. OASIS, and other special operating

systems for Z80 microcomputers. It is designed for TRS-80, Cromemco, North Star, Onyx, Gnat, Vector Graphic, Ithaca Intersystems. and other Z80 microcomputer systems. Versions are available for 8086, Z8000. and 68000 microprocessorbased systems. Software to emulate X.25 protocol is also available. The price for the RBTE is S500 for a singleuse license. The operator manual and the programmer manual are available for S25 and SI5, respectively. For complete details, contact Winterhalter and Associates Inc. 3825 Zeeb Rd. Dexter Ml 48130, (313) 665-5582.

Circle 434 on inquiry card

This Program Moves

Files Through VlslCalc

VU #3 is a utility program for Personal Software's calculating and bookkeeping program VisiCalc. VU #3 allows the user to enter data into VisiCalc from any program by inserting data into an array defined by VU #3. The program can transfer data generated from VisiCalc into any of the user's programs through another array as defined in the instructions. VU #3 runs on the Apple II. It is available from Progressive Software. POB 273, Plymouth Meeting PA 19462.

Circle 435 on inquiry card

Wordbank for

the TRS-80 Model II

The Wordbank is a word-processing program for writing letters, reports, manuals, or other documents on a one-time or repetitive basis. Up to 7500 document lines are available; lines may be added, changed, or deleted; page control is user-assigned or automatic; and automatic line numbering and pagination are included. Wordbank requires a TRS-80 Model II with 64 K bytes of programmable memory, one floppy-disk drive, and a printer. Wordbank is available from Taranto and Associates Inc. POB 6073. 121 B Paul Dr. San Rafael CA 94903, (415) 472-2670. for SI49.95.

Circle 436 on inquiry card

Pascal Data Base

Written In UCSD Pascal

The Pascal Database can be used for mailing lists, accounting, inventory,job estimates, sales analysis, and property management. The data base can update, search, and traverse data-base files; sort on multiple fields; and maintain records in several sorted orders. There is user-programmable screen formatting and automatic indexing of information at data entry. Users can define file, record, and field names. Reports can also generated. The Pascal Database for the Apple II costs S400, and it is available from Arizona Computer Systems Inc. POB 125, Jerome AZ 86331. (602) 634-7301.

Circle 437 on inquiry card

General Ledger System for Prodigy Computers

Prodigy Systems has a smallbusiness accounting package with a general-ledger program for its computers. Features include a user-defined chart of accounts, current balances, audit trail, and the ability to produce comparative statements. The system allows users to format their own reports. The reports include account charts, general ledger, trial balance, income statements, balance sheets, and transaction proof listings. The general-ledger system includes accounts receivable, accounts payable, and payroll packages. Contact Prodigy Systems Inc. 497 Lincoln Hwy. Iselin NJ 08830. (201)

283-2000. Circle 438 on inquiry card

344 March 1981 © BYTE Publications Inc

MC/t.

P.O. Box 4430X Santa Clara, CA 95054

ELECTRONICS

INTEGRATED CIRCUITS

Will calls: 2322 Walsh Ave. (408) 988-1640 TWX 910-338-2139 Samedayshipment. First line parts only. Factory tested. Guaranteed money back. Quality IC's and other components at factory prices.

740irnL

740DN

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74LS00 TTL

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74LS14N

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74152BN

74LS30N

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74LS90N

74LS93N

74LS9SN

74LS107N

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74LS132N

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74LS155N

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21141450ns 4.00

4116 200ns 4.50 8,'4116 2Q0ns26.95

MM5262 .40

MM5280 3.00

MM532Q 9.95

MM5330 594

P0411D-3 4.00

PD4UD-4 500

P5101L B.95

4200A 9.95

B2S25 2.90

91L02A 1.50

HD0165-5 6.95

MM57100 4.50

GIAY38500-1 9.95

MCM66751A 9.95

9368 3.50

BBpin edge 4 00

100pm edge 4.SO

100 pin Edge WW 5 25

IC SOCKETS

Solrtef Tin Law Profile FIN tUP PIN 1UP

20 29 40

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56 key ASCII keyboard kil Fully assembled " iy ASCII Kybosrd kil assembled

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CONTINENTAL SPECIALTIES In I to CI Campleie line ot Breadboard lesi equip MAX-100 8 dlgll Freq. CI;. IMS.US

OK WIRE WRAP TOOLS!* HOC*

Poitibiu Multimeter 118.00

CompioK Una ot AP Product* in Hack.

SPECIAL PRODUCTS MM5B65 Stopwatch Timer

with 10 po spec 9 00

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5 11

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KETBOAHD ENCODERS

AY5-2376 S12 SO

AY5 3600 17.95

AY5-91O0 1050

AY5-92O0 '6 50

74C922 5.50

74C923 550

HO0I6S-5 6.95

AY5-9400 10 50 0 Canntdan HS232

OB25P 3.62

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12V 500 ma wall plug 4

12V 1 amp wall plug B 10/15 VACB/1EVAwallpl<ig 9 DISPIAYLEOS

MAN1 CA 270 2

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MAN72/74 CA'CA 300 1

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OL7O7/OL707R CA 300 1

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3.95 8223

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StapwltcriKII 26.95

Aula Clack KM 17.SS

Digital Clack KI1 14.95

■KlIK Eprom Kit Dllt PROMS) SB9.00

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Disciele Componenl Steriei Pick tf.57

PROM Eraser

assembled. 25 PROM capacity $37.50 (with timer $69.50). 6 PROM capacity OSH/V UL version $69.50 (with timer $94.50).

Z80 Microcomputer

16 bitl/O, 2 MHz crock. 2K RAM. ROM Breadboard space. Excellent for control. Bare Board $28.50. Full Kit $99.00. Monitor $20.00. Power Supply Kit $35.00. Tiny Basic $30.00

S-100 Computer Boards

BK Static Godbout Econo IIA Kit 149.00 16K Static Godbout Econo XIV Kit 269.00 24K Static Godbout Econo XX-24 Kit 414.00 32K Static Godbout Econo XX-32 Kit 537.00 16K Dynamic RAM Kit 269.00

32K Dynamic RAM Kit 326.00

64K Dynamic RAM Kit 399.00

Video Interface Kit $139.00

80 IC Update Master Manual $39.00

Comp. ICdataselector, 2700 pg. master reference guide. Over 51.000 cross references. Free update service through 1980. Domestic postage $3.50.

Modem Kit $60.00

State of the art, orig., answer. No tuning necessary. 103 compatible 300 baud. Inexpensive acoustic coupler plans included. Bd. only $17.00.

LRC 70004 Printer $389.00

40/20 column dot matrix impact, std. paper. Interlace all personal computers.

64/40/32/20 version $405.00. Optional cables available.

LRC 7000 printer Interface cable lor Super Ell with software $35.00

NiCad Battery Fixer/Charger Kit

Opens shorted cells that won't hold a charge and then charges them up, all in one kit w/full parts and instructions. $7.95

Rockwell AIM 65 Computer

6502 based single board with full ASCII keyboard and 20 column thermal printer, 20 char, alphanumeric display, ROM monitor, fully expandable. $405.00. 4K version $450.00. 4K Assembler $85.00, 8K Basic Interpreter $100.00.

Special small power supply for AIM65 assem. in frame $54.00. Complete AIM65 in thin briefcase with power supply $499.00. Molded plastic enclosure to fit both AIM65 and power supply $47.50. Special Package Price: 4K AIM, 8K Basic, power supply, cabinet $625.00.

AIM65/KIM/VIM/Super Elf 44 pin expansion board; 3 female and 1 male bus. Board plus 3 connectors $22.95.

60 Hz Crystal Time Base Kit $4.40

Converts digital clocks from AC line frequency to crystal time base. Outstanding accuracy.

Video Modulator Kit $9.95

Convert TV set into a high quality monitor w/o affecting usage. Comp. kit w/full instnje.

Multi-volt Computer Power Supply

8v 5 amp, ±18v .5 amp, 5v 1.5 amp, -5v .5 amp, 12v .5 amp, -12v option. ±5v, ±12v are regulated. Basic Kit $29.95. Kit with chassis and all hardware $43.95. Add $4.00 shipping. Kit of hardware $14.00. Woodgrain case $10.00. $1.50 shipping.

RCA Cosmac 1802 Super Elf Computer $106.95

Compare features before you decide to buy any other computer. There is no other computer on the market today that has all the desirable benefits of the Super Elf for so little money. The Super Elf is a small single board computer that does many big things. It is an excellent computer for training and for learning programming with its machine language and yet it is easily expanded with additional memory, Full Basic, ASCII Keyboards, video character generation, etc.

Before you buy another small computer, see if it includes the following features: ROM monitor; State and Mode displays; Single step; Optional address displays; Power Supply; Audio Amplifier and Speaker; Fully socketed for all IC's; Real cost of in warranty repairs: Full documentation. The Super Ell includes a ROM monitor tor program loading, editing and execution with SINGLE STEP lor program debugging which is not included in others at the same price. With SINGLE STEP you can see the microprocessor chip operating with the unique Quest address and data bus displays belorc, during and alter executing instructions. Also, CPU mode and instruction cycle are decoded and displayed on 6 LED indicators.

An RCA 1861 video graphics chip allows you to connect to your own TV with an inexpensive video modulator to do graphics and games. There is a speaker system included for writing your own music or using many music programs already written. The speaker amplifier may also be used to drive relays for control purposes.

plus load, reset, run, wait, Input, memory protect, monitor select and single step. Large, on board displays provide output and optional high and low address. There is a 44 pin standard connector slot for PC cards and a 50 pin connector slot tor the Quest Super Expansion Board. Power supply and .sockets tor all IC's are included in the price plus a detailed 127 pg. instruction manual which now includes over40 pgs. of software info, including a series of lessons to help get you started and a music program and graphics target game. Many schools and universities are using the Super Elf as a course of study. OEM's use it for training and R&D. Remember, other computers only offer Super Elf features at additional cost or not at all. Compare before you buy. Super Ell Kit $106.95, High address option $8.95, Low address option $9.95. Custom Cabinet with drilled and labelled plexiglass front panel $24.95. All metal Expansion Cabinet, painted and silk screened, with room for 5 S-100 boards and power supply $57.00. NICad Battery Memory Saver Kll$6.95. All kits and options also completely assembled and tested.

Questdata, a software publication for 1602 computer users is available by subscription for $12.00 per 12 issues. Single issues $1.50. Issues 1-12 bound $16.50. Tiny Basic Cassette $10.00, on ROM $38.00, original Elf kit board $14.95. 1802 soltware; Moews Video Graphics $3.50. Games and Music $3.00, Chip 8 Interpreter $5.50.

A 24 key HEX keyboard includes 16 HEX keys

Super Expansion Board with Cassette Interface $89.95

This i s truly a n astounding value! This board has been designed to allow you to decide how you want it optioned. The Super Expansion Board comes with 4K of low power RAM fully addressable anywhere in 64K with built-in memory protect and a cassette Interface. Provisions have been made for all other options on the same board and it fits neatly into the hardwood cabinet alongside the Super Elf The board includes slots for up to 6K ot EPROM (2706. 2756, 2716 or Tl 2716) and is fully socketed. EPROM can be used forthemonitorand Tiny Basic or otherpurposes. A IK Super ROM Monitor $19.95 is available as an on board option in 2708 EPROM which has been preprogrammed with a program loader/ editor and error checking multi file cassette read/write software, (relocatable cassette file) another exclusive from Quest. It includes register save and readout, block move capability and video graphics driver with blinking cursor. Break

Quest Super Basic V5.0

A new enhanced version of Super Basic now available. Quest was the first company worldwide to ship a full size Basic for 1802 Systems. A complete function Super Basic by Ron Cenker including floating point capability with scientific notation (number range ±.17E3"), 32 bit integer ±2 billion; multi dim arrays, string arrays; string manipulation; cas

points can be used with the register save feature to isolate program bugs quickly, then follow with single step. If you have the Super Expansion Board and Super Monitor the monitor is up and running at the push of a button. Other on board options include Parallel Input and Output Ports with lull handshake. They allow easy connection ot an ASCII keyboard to the input port. RS 232 and 20 ma Current Loop for teletype or other device are on board and if you need more memory there are two S-100 slots for static RAM or video boards. Also a 1K Super Monitor version 2 with video driver for full capability display with Tiny Basic and a video interface board. Parallel I/O Ports $9.85, RS 232 $4.50, TTY 20 ma l/F $1.95, S-100 $4.50. A 50 pin connector set with ribbon cable is available at $15.25 for easy connection between the Super Ell and the Super Expansion Board. Power Supply Kit tor the complete system (see Multi-volt Power Supply).

Ohio Scientific Computers

CIP Series 2 $455.00. Like an Apple at less than halt the price! CIPMF Series 2 $1199.00. Minifloppy version with additional RAM/ROM. Complete software and peripherals available. Send for free brochure.

Gremlin Color Video Kit $69.95

32 x 16 alpha/numerics and graphics; up to 8 colors with 6847 chip; 1K RAM at E000. Plugs into Super Elf 44 pin bus. No high res. graphics. On board RF Modulator Kit $4.95

1802 16K Dynamic RAM Kit $149.00 Expandable to 32K. Hidden refresh w/clocks up to 4 MHz w/no wait states. Addl. 16K RAM $63.00 Tiny Basic Extended on Cassette $15.00 (added commands include Stringy, Array, Cassette I/O etc.) S-100 4-Slot Expansion S 9.95 Super Monitor Vl.l Source Listing $15.00

sette I/O; save and load, basic, data and machine language programs; and over 75 statements, functions and operations. New improved faster version including renumber and essentially unlimited variables. Also, an exclusive user expandable command library.

Serial and Parallel I/O included. Super Basic on Cassette $55.00.

Elf II Adapter Kit $24.95

Plugs into Elf II providing Super Elf 44 and 50 pin plus S-100 bus expansion. (With Super Expansion). High and low address displays, state and mode LED's optional $18.00.

Super Color S-100 Video Kit $129.95

Expandable to 256 x 192 high resolution color graphics. 6847 with all display modes computer controlled. Memory mapped. 1K RAM expandable to 6K. S-100 bus 1802,8080,8085, Z80 etc. Dealers: Send lor excellent pricing/margin program.

Editor Assembler $25.00

(Requires minimum nf 4K for E/A plus user source)

1802 Tiny Basic Source listing $19.00

Super Monitor V2.0/2.1 Source Listing $20.00

TERMS: $5.00 min. order U.S. Funds. Calil residents add 6% tax.

$10.00 min. BankAmericard and Master Charge accepted. $1.00 insurance optional. Postage: Add 5%. COD. $10.00 min. order.

FREE: Send lor your copy ol our NEW 1980 QUEST CATALOG. Include 48c stamp.

Circle 81 on Inquiry card.

BYTE March 1981 345

What's New?

PUBLICATIONS

BYTE Books Brings

You Two Books from

Steve Garcia

Ciarcia's Circuit Cellar, Volume II,

is a collection of articles from BYTE. The book tells you about microcomputers and how you can use them in various environments. Construction projects show you how to build a computer-controlled home-security system, computerize home appliances, make an inexpensive joystick, send digital information over a light beam, and explore the Intel 8086 microprocessor system-design kit. Each project is presented in such a way that even beginners should have little trouble making and enjoying these useful devices. Ciarcia's Circuit Cellar, Volume II, costs S11.95. Build Your Own Z80 Computer is for the engineer, computer technician, student, and anyone interested in building his or her own computer. The computer is based on the Zilog ZBO microprocessor. Each computer subsystem (ie: I/O, serial interface, keyboard, memory, etc) is fully explained and supported by proven design and testing information. The board contains a 2 K-byte operating system, serial and parallel ports, hexadecimal display, and audio-cassette mass storage, with expansion to include a video terminal. You can modify this system to meet your individual needs. All required components are readily available and have been selected to allow simple system checkout. This book costs SI5.95. Both books by Steve Ciarcia are published by BYTE Books, 70 Main St, Peterborough NH 03458, |B00) 258-5420; in New Hampshire (603) 924-9281.

Circle 439 on inquiry card

Microcomputer and Minicomputer Supplies

Daily Business Products Inc's 68-page catalog features supplies and accessories for all microcomputers, minicomputers, and word-processing systems. For a free copy, contact Daily Business Products Inc, 464 New York Ave, Huntington NY 11743, (800) 645-5332; in New York (212) 594-8065.

Circle 440 on inquiry card

1981 Radio Shack Catalog

Radio Shack's 1981 catalog is available free at Radio Shack stores and dealers. The catalog features computer and stereo equipment, toys and electronic games, plus parts and accessories for home entertainment, or hobbyists and experimenters. The TRS-80 Pocket Computer, the Color Computer, the Model III system, six new stereo receivers, five cassette tape decks, twelve new telephone products, home-alarm systems, and thirteen new electronic calculators are among the items in the catalog.

Circle 441 on inquiry card

Datapro Directory of Small Computers

This guide is designed to help dataprocessing professionals and managers locate, compare, and evaluate small-computer systems, software, peripherals, services, and the companies that manufacture and distribute them. This directory service is updated monthly. More than 200 microcomputer systems are reported on, with each report giving a summary of current models, memory size, base price, primary uses, popular options, principal applications, and more. The reports have details on hardware specifications, such as the processor used, memory, display, keyboard, direct-access storage, printers, data communications, and I/O electronics. Software information covers languages, operating systems, database-management systems, and applications programs. An applications index, a section on advice and guidelines on purchasing, a listing of over 16,000 companies, and sections on computer concepts, user ratings, and user groups are included. The subscription rate is S330. Each subscription to the Datapro Directory of Small Computers includes two volumes, 12 monthly supplements, 12 monthly newsletters, and use of a telephone-inquiry service. Contact Datapro Research Corporation, 1805 Underwood Blvd, Delran NJ 08075, (609) 764-0100.

Circle 442 on inquiry card

Time-Sharing and

Remote-Computing

Services Report

Details on 117 remote-computing services, including results of a user survey, are available in this report from Datapro Research Corporation. All About Time-Sharing and Remote Computing Services gives you the name of the service, areas currently served, type of computer, number of simultaneous users, conversational and batch terminals supported, programming languages, principal applications, and pricing information. A listing of vendors is included. The report provides a discussion of user benefits and disadvantages, a guide for evaluation and selection of remote-computing services, and an index of application programs and user programming aids. The report is available for S15 per copy from Datapro Research Corporation, 1805 Underwood Blvd, Delran NJ 08075. (609) 764-0100.

Circle 443 on inquiry card

Packaging and

Breadboardlng

Materials Brochure

A brochure from Vector Electronic Company Inc describes 109 electronic packaging and breadboarding products available at electronic and personal-computer component stores. Highlighted are microcomputer interface boards, Vector products, motherboards, cases, tools, wiring terminals, and kits. A price list is included. Contact Vector Electronic Company Inc, 12460 Gladstone Ave, Sylmar CA 91342,(213)365-9661.

Circle 444 on inquiry card

SDK-85 Experiments

The 8085 Microprocessor—Fundamentals and Applications: 76 Control Experiments with the Intel SDK-85, by Dr Howard Boyetis available from MTI, 14 E 8th St, New York NY 10003, (212) 473-4947. Other books from MTI describe hands-on experiments with the 8080, 8085, and 8048 microprocessors.

Circle 445 on inquiry card

346 March 1981 © BYTE Publicalions Inc

A-D & D-A CONVERTER

Z80 MICROCOMPUTER

6522 APPLE II INTERFACE

'it

JBE A-D & D-A Converter can be used with any system having parallel ports

• Interfaces with JBE Parallel I/O Card

• D-A conversion time — 5 jjls • A-D conversion time — 20 fis • Uses JBE 5V power supply • Parallel inputs & outputs include 8 data bits, strobe lines & latches • Analog inputs & outputs are medium impedance 0 to 5 volt range. JmM

79-287

Bare Board $29.95

ASSM. $79.95 Kit $59.95

6502 MICROCOMPUTER

This control computer has: • 1024 bytes RAM (two 2114s) • 2048 bytes EPROM (2716) • Uses one 6522 VIA (comp. doc. incl.) • Interfaceswith JBE Solid State Switches & A-D & D-A Converter «Uses JBE 5V power supply • 2716 EPROM available separately (2716 can be programmed with an Apple II & JBE EPROM Programmer & Parallel Interface) • 50 pin connector included in kit & assm.

80-153

Bare Board $24.95

ASSM. $110.95 Kit$ 89.95

SOLID STATE SWITCH

Your computer can control power to yourl,printer, lights, stereo & any 120VAC appliances up to 720 watts (6 amps at 120VAC). Input 3 to 15VDC • 2-14MA TTL compatible • Isolation — 1500V • Non zero crossing • Comes in 1 or 4 channel version • Includes doc. for interfacing with Dimmer Control.

79-282-1 ASSM. $13.95

Bare Board $6.95 Kit $10.95

79-282-4 ASSM. $49.95

Bare Board $24.95 Kit $39.95

APPLE II DISPLAY BOARD

JBE is announcing a single board dedicated computer designed for control functions. It features: • A Z80 Microprocessor software compatible with the Z80, 8080 & 8085 Microprocessors • Uses a Z80 PIO chip for I/O which has 2 independent 8 bit bidirectional peripheral interface ports with handshake & data transfer control • Uses one 2716 EPROM (2K)& two 2114 RAM memories (1K) 'Single 5V power supply at 300MA req. 'Clock frequency is 2MHz, RC controlled • Board comes with complete doc. • 50 pin connector is included • 2716 EPROM available separately.

10-280 ASSM. $129.9$

Bare Board $29.95 Kit $119.95

DIMMER CONTROL

JBE Dimmer Control features: • 4 channels • 256 brightness levels • Onboard power supply • Four 8 bit parallel input ports 'Interfaces with JBE Solid State Switch & Apple II Parallel Interface.

80-146

Bare Board $25.95

ASSM. $89.95 Kit $79.95

POWER SUPPLIES

• Use wall transformers for safety -•Protected against short circuit and thermal breakdown.

5 VOLT POWER SUPPLY Rated at 5V 500MA • Operates JBE A-D & D-A Converter, Z80 & 6502 Microcomputers, 8085 & 8088 Microcomputers. 80-160 ASSM. $20.95

Bare Board $8.95 Kit $16.95

± 12 VOLT POWER SUPPLY Rated at ± 12V 120MA • Can be used as a single 24V power supply • Ideally suited to OP-AMP experiments. 80-161 ASSM. $22.95

Bare Board $8.95 Kit $18.95

80-144

Bare Board $25.95

ASSM. $49.95 Kit $42.95

• Has run-stop, single step switch • Has 16 address LEDs, 8 data LEDs & 1 RDY LED

• All lines are buffered.

ICS

6502 6522 Z80

Z80 PIO 27165V

$9.95 $9.95 $9.95 $9.95 $19.95

• Interfaces printers, synthesizers, keyboards, JBE A-D & D-A Converter & Solid State Switches • Has handshaking logic, two 6522 VIAs & a 74LS74 for timing. Inputs & outputs are TTL compatible.

79-295 ASSM. $69.95

Bare Board $22.95 Kit $59.95

2716 EPROM PROGRAMMER

JBE 2716 EPROM Programmer was designed ito program 5V 2716 EPROMS • It can also , re«id 2716s. It interfaces to the Apple II using JBE Parallel I/O Card & four ribbon cable connectors • An LED indicates when power is being applied to the EPROM • A textool zero insertion force socket is used for the EPROM • Comes with complete doc. for writing and reading in the Apple II or Apple II + • Cables available separately.

80-244

Bare Board $24.95

ASSM. $49.95 Kit $39.95

BARE BOARDS

APPLE II EXTENDER BOARD

3Va" X 21/z". Price includes 50 pin

Apple Connector.

80-143 $12.95

8085 3 CHIP SYSTEM

State-of-the-art system using an 8085, 8156 & either an 8355; or 8755

• Instruction set 100% upward compatible with 8080A.

Bare Board $24.95

8088 5 CHIP SYSTEM

An 8086 family microcomputer system using an 8088 CPU, 8284, 8155, 8755A & an 8185. Bare Board $29.95

CRT CONTROLLER

This intelligent CRT Controller is based on an 8085A Microprocessor & an 8275 Integrated CRT Controller. It features: • 25 lines, 80 characters/line

• 5x7 dot matrix • Upper case only

• Two 2716s • Serial Interface RS232 & TTL • Baud rates of 110, 150, 300, 600, 1200, 2400, 4800 & 9600

• Keyboard scanning system • Req's. unencoded keyboard • Uses +5V & ± 12V power supplies.

Bare Board $39.95

50 pin connector STD. Dip Jumpers 16 Pin, 2 ft.

$5.95 $4.25

John Bell Eivgiiveeriivg

ALL PRODUCTS ARE AVAILABLE FROM: JOHN BELL ENGINEERING • P.O. BOX 338 DEPT 8 • REDWOOD CITY, CA 94064 • ADD 6% SALES TAX IN CALIFORNIA • ADD 5% SHIPPING & HANDLING

(415)367-1137

BYTE March 1981

347

SNTdldN SN7416N SN7417N SN7420N SN7421N SN7422N SN7423N SN742SN SN7426N SN7427N SN7429N SN7430N SN7432N SN7437N SN743BN SN7439N SN7440N SN7441N SM7442N EN7443N 5N7444N SN7445N SN7446N SM7447W SM744BN SN7450N SN7451N SN7453N SN74S4N SN74S9N SN7460N SN7470N SN7472N SN7473N SM747-1N SN747SN SN7476N SN7479N SN74BON SN74B1N SN7482N EN74B3N EN7485N EN7486N SN74B9N SN7490N SN7491N SN7492N SN7493N SN7494N SN7495N SN7496N

SN74109N SN74116N SN74121N SN74122N

SN741B5N SN741B6N SN74188N SN74190N SN74191N SN74192N SN74193N SN74194N SN74195N SN74196N SN74197N SN74198N SN74I99N SN74221N SN74251N SN74273N SN74279N SN74283N SN74284N SN74285N 5N74290N SN7429BN

2.15

3.90 3.90

CMOS

CD4000

CD4001

CD4002

CD40O6

CD4C07

CD4008

CD4O09

CD4010

CD4011

CD40I2

CD4013

CD4014

CD4015

CD4016

CD4017

CD4018

CD4019

CD4O20

CD4021

CD4022

CD4023

CD4024

CD4025

CD4027

CD4028

CD4029

CD4O30

CD4031

CD4032

CD4034

CD4035

CD4037

CD40.I0

CD4041

CD4042

CD4043

CD4044

CD4046

CD4047

CD 40-18

CD.10.19

CD4050

CD4051

CD4052

CD.1053

CD4055

CD.1056

CD4059

CD4060

CD-1066 ,

CD4069

CD4070

CD4071

CD4072

CD4073

CD4075

CD4076

CD4077

CD4078

CD40B1

CD40B2

CD40B5

CD4089

3 95 2 95 9.95

CD4093 CD4094 CD4098 CD4099

M C14 419

CD4501

CD4502

CD4503

CD4S05

CD4506

CD4507

CD4508

CD4510

CD4511

CD4512

CD4515

CD4516

CD4518

CD4520

CD4555

CD4556

CD4566

74C0D

74C02

74C04

74C08

74C10

74C14

74C20

74C30

74C32

74C42

74C4B

74C73

74C74

74CB5

74CB9

74C90

74C93

74C95

74C107

74C151

74C154

7-1C157

74C160

74C161

74C163

74C16J

74C173

74C174

74C175

74C192

74C193

74CT95

74C922

74C923

MM80C95

f.T.'a0C97

12.95 12.95 12.95 12.95 8.95

2.49 3 5G 2 10 2 39 2.30 2.39 2.39 2.59 2 75 2.75 2 39

ADVANCED

COMPUTER PRODUCTS

74LS78N

74LSB3AN 74LS85N 74LS86N 74LS90N 74LS92N 74LS93N 74LS95N

1LS96N ILS107N ILS109N

ILS12SN ILS126N .LS132N .LS136N ILS138N .LS139N

7.1LS155N 74LS156N 74LS157N 74LS158N 74LS160N 74LS161N 741S162N 74LS163N

74LS24BN

74LS249N

74LE251N

74LS253N

74LS257N

74LS25BN

74LS259N

74LS260N

74LE261N

74LS266N

74LS273N

74LS275N

74LS279N

74LS2S3N

74LS290N

74LS293N

74LS295N

74LS29BN

74LS324N

74LS347N

74LS34BN

74LS352N

74LS353N

74LS363N

74LS365N

74LS366N

74LS367N

74LS368N

74LS373N

74LS374N

74LS375N

74LS377N

74LS385N

74LS386N

74LS390N

74LS393N

74LS395N

74LS399N

74LS424N

74LS668N

74LS670N

81LS95N

81LS96N

LINEAR

LM10SH LM10SAH LM300H LM301CM/H LM304H LM305H LM306H LM307CN;H LM308CN/H LM309K LM310CN LM311D/CN/H LM312H L M 3171 LU318CN/H LM319N/H LM320K XXLM320T-XXLM320H-XXLM323K LM324N LM339N LM340K-XXLU340T-XXLM340H-XXLM344H LM34BN LM35BCN LM360N LM372N LM376N LM377N LU3B0CM/N LM381N LM383T LM36BN LM387N LU390N NE53W/T NE555U NE556N NE561T NE562B NE565N/H NE566HA/ NE567V/H NE592N LM702H LM709N/H LM710N/H LM71 1N/H LM715N LM723N/H LM733N/H LM739N LM741CN/H LM741CN-14 LM747N/H LM748N/H LM760CN LM1310N

M1820N M1850N M1889N M21 UN LM2900N L M 2 9 01N L M 2 917 N CA3013T CA3018T CA3021T CA3023T CA3035T CA3039T CA3046T LM3053N CA3059N CA30eON CA3062N LM3065N CA3080N CA308 1N CA3082N CA3083N CA3086N CA3089N CA3096N CA3097N CA3130T CA3140T CA3146N CA3160T CA3 190N CA3401N MC3423N MC3'I60N SG3524N CA3600N LM3900N LM3905N LM3909N RC4131N BC4136N RC4 15 1N RC4 19-I BC4 195 ULN2001 ULN2003 SN75450N SN75451 N SN75452N SM75453N SN75^154N SN75-191N SN75492N SM75493N SN75494N

3 49

299 2 7 5

2.49 2 49 2 49

3 95 3 95 350

RETAILSTORESOPEN MON-SAT

BECKMAN

Dicnr.il Multimeters

p3 The TECH 300 has n'

-$(C the abcte feaiurts. b

I

^( \ VC-201 Vinyl Carrying Cfl

r^T-A DC-SOP Dclu.r C-irryinri <

y*T \ HV-211 Mitjh V(!lt,it)i> P«,

.' !\ RP-221 RP Probe

""'*i\ Cl-P:U AC Curr-nl Cl.irm.

TECH 300 Digital Multimeter . TECH 310 Digital Multimeter .. TECH 330 Digital Multimeter . VC-201 Vinyl Ciirrymn Case .

e Probe

<*?-' DL-241 Deli TL-242 Spare

HP

r MUSIC MACHINE 9*

mm WITH 9 VOICES!

• NEW Jses taint Slate ul me An LSI Tethnolngy • Rraunts oily tv sfo1(Di9m!Ce5 • Ui« Ihree Ari-8910 5 loprMuce nine voices • PiavsraiiSit censrau.miy iheALFFlcirfl • Alt sHIWKKSWted ■ APPlE'-llmrowtiDie

ASSEMBLED AND TESTED 31 29.95

FLOPPY DISK DRIVES

Tandon TMlOO-l 5'V Di5h Drive ,. . 249 95 MPI B51-5V.4Q tracks . , ,239.95

Shugan SA400-5'.'35 tr;lck5 . . 295.00

Shugait800/801B 8" 475.00

Siemens Shugan Conifiaiibte Model

FDD-120-8D . .... 429 00

PERSCI Model 277 Dual l 19500

WANGO/SIEMENS SV Drive 290.00

MPI B52 S"V Dual. 348.00

WANGO/SIEMENS 2B2 Dual 5"." .... 395 00

WANGO/SIEMENS 82 290.00

MPI 9 1 Double Track Oensily Sinfle Side.

80 Tracks 375.00

MPI 92 Double Track Oensily Double Side.

160 Tracks • ,475 00

SUBCONTINENTAL SPECIALTIES

Model LM-3 40-cliannel Logic Momlor 585 00 Motftl LM-I Logic Monitot . 60 00

Modtl LH-2 Logic Momlor 14700

BHU-IOQ 100 MHz PorTabie Frequency Couniei

. . . 14900

Modtl LP-I Digital Logic Probe. . 50 00

Model LP-Z Economy Logic Probe 38 00

Model LP-3 High Speed Logic Ptobe .. . 7700 Model LPK-1 Logic Probe Kil . 21.95

Model LTC-1. LTC-2 Logical Analysis Kits.. .220/250

a, y Proto Clips

' .^> 11-Pin Clip PC-14 .,. S 41 16-PinCiip PC-16 S 4t

M-PinCl.p PC-24 S 9.50

40-Pjn Clin PC-40 S14 9S

Ptoto Boards

1695 PB-ltW 5400

00 18 00 P8-203 97.00

PB-101 21 00 PB-20HA . 14900

PB-102 25 00 PB-203A-Kil. 129.00

PB-103

SEMICONDUCTORS

SPEAKA*^tV

DIGITALKER"

Speech Synthesis System

Apple® II 16K Apple® II Plus

DISK SYSTEM SPECIAL

Apple II Plusw/48KSupermod Video Modulator Disk II w/Controller Integer Based ROM Card. ACP PRICE $1969.00

$1150

Centronics Printer I/O Applesoft II Firm* Apple Clock Ifitrol X-lG System Introl X-10 Controller All Music Synthesiser 16 Ch Analog Inpul 2 Cb Analog Output. 13-Key Keypad Visi-Calc

S18900 DS55 Dig.-Sector

10.00 Apple Grannies Tab^i

18900 DC Hayes Modem 11

26900 CisMI wConlrtftB 1 Ob ill

17995 oak 11

26995 Pascal Lang System

259.95 Parallel Printer Card

249.95 Communications Card

164.95 BuSinessSottwarePkg

119.95 Cwvjs 10 Megabyte Onve 12500

534900 'nteger ROM Card

67500 I99i

5-00

Prcto Carfl

M 6 R Modulate

Cassette... . ...

16K Upg/arJe Kn 450 00 Desktop Plan 165 00 8" Floppy Conlrciier iB9 00 Hejfisncs Soeecmab 62500 Romplus + Supertaiker Cashier

^?.'.

\appUz///$39Q5

• Aople III Option A: Apple II 96K.

Inlormahon Analyst Package, • APP'e l« Option C: Same as

12" B/W Monitor S3995.00 Option A Plus: Disk II for Apple III.

.Apple III Option B: Same as Siienlyp-Thermal Pr.nter . S4735O0

Option A Plus: Disk 11 (or • TO Sbbslilule 1 2QK Apple III tor

Apple III S4395.00 96K Apple III AddS'150 00

NEW APPLE PRODUCTS

tPPLE FAN**- [ iiT3*-NrwfH

5 Iror

JpW S.1995

a Aople Complplely comwiitue with Pascal S3Z995

1 HAfi WAND1 Heihtetl Packard HEDS-3000 Bar Co*

WeriiCB] la ADKe SI9900

1 'SEC APPLE A/D"' - B Ctiannel A/TJ Interlace corroietely assembled arc! lestea S9950

1 VISTA APPLE AC TRACK DISK ORIVE" Floppy AcH-ar, lor

Apple PA" 8Q TPI S45900

< APPLE FORTRAN" .... . 517500

i APPLE CRYPTEXr la daia encryption and

security S>U900

i B2'A?" GraDhics Interlay Card by 6asc 2 SI5995

' B" Dish Drives tor Appl e.Cwtloller. DOS. Twd S'

dinescaMMard cacle .... SM5D0C i-MlCBOMODEM"-DC Hayes.. .. S3I995

i 'OIGISECTOP1 ConvEHSvifleo input to Hi-Res

S3499S

11 Revision Kil 2D«» (

dli'ig Add Hiatal error C d man al Venito lileei

• ViSiCac Keypa

neysad

!. ESC.

lir.paWli hly S16900

S6500

S55000 i Pefticed S145B0 S0500

Avail Soon 561900

S3J9CC

SS49CC a Coupv-ter Systems AI'PLE Cioc*

S1J-J9 5 Oca-d Iff APPLE CPM 22 I M BASIC

53250C i Mfcrccoducts Keypa

517500

NEW APPLE SOFTWARE

I CTBERSTKIKE- Apple II

i "Bllh BimU"- Hi-Rcs SumialiM ot Western GunlinM

andSkeet Srirolnig Sa.it aultilir as Nasir S2995

5 ■ Afpitui Pinntr PkH;i" S7495

•;■ 'Nev-dds t»i (or ;»-s-j-:.

7 MEWIAPPK Z-60 EPVM Soliware Call lor Price

ON A PLUG-IN CARD.

EXPANSION CHASSIS

A ATARI 800 & 400

Personal Computer System

ATARI 800 $825.OO ATARI 400 $449.00

ATARI BOO Includes: Computer Console. BASIC Lang. Cartridge. Edu> System Master Cartridge, BASIC Language Programming Manual. 800 Opet I w/Notebook. 16K RAM Modulo. Power Supply, TV Switch Box

ot 144 word.. S485.00

Solium- fiOM CirHilm

Ba5ic SX'tVQi

S-asiC Gjh» Progtarrn

9'aru D.ikenti Junius Cntniin

SINGLE BOARD COMPUTER SELECTION GUIDE

rRuCESsofl «cr

ENCLOSURE

Add ?y <J!i

A(J() ^I'lS

PROCESEDR ACP PRICE

Z80 23!! 110

6502 375(1(1

Texas Instruments

99/4 PERSONAL COMPUTER

Superior Color. Music, Sound S Graphics 3, a Powerful Extended Basic- All Buill-ln Now' Special TV. ^

Adapter lets you use your existing T.V. set as a computer display.

INTELLIVISION

ACP LOW PRICE

$259.95

GAME CARTRIDGES

-, CA 95131 • {408) 946-7010

P.O. Box 17329 Irvine, Calif. 92713

Direct Order Lines: (714) 558-8813

(800) 854-8230 or (800) 854-8241

FOR INTERNATIONAL ORDERS: 1310 E. Edlnger (714) 953-0604 SantaAna,CA92705 TWX:910-59S-1565

348 BYTE March 1981

Circle 275 on Inquiry card.

^/PRODUCTS

STATICX /RAM BOARDS

• S-100 32K (uses 2114) I^Tb^

ASSEMBLED Kit (&* P

450ns. 389.00 450ns. 339.00

250ns. 409.00 250ns. 359,00

Bare Board 39,95 Bare Board w/all parts less mem. 99.95

MODEL 2065

64 K DYNAMIC RAM

MODULE $600.00

• CHi^nrftOiEEE PriDCWd S lCO

• SuccDcisiuSfil-iyiJefioilia^s

• OWrairs wiih trillion 80S 0 or a ^

Z-80 MSMS-tOCI system.

on power-on and resel

FLOPPY DISK CONTROLLER S400. ZBO CPU BOARD S300.

■.#

TRS80 ADD-ON

The VISTA V-80 Disk Drive System

Mm for lm Speed. Cipictty. Prlca.

IN Vlitt V-BD mini disk tytltm it S Until filler thin

llii TRS-BO. 23% more iloiigi cipKlty. inri cot* leu.

• Visia oners tl)?K bytes to Raft Shack's 89K That's 13K more Bytes per dnvr.

• The V-BO operates at 12ms versus arjrn; lw TRS-8Q Out drive can operate a! 5ms. but wily 50% or TH5-S0 will ooerjte at that speed. I here lore. Vista haj puipcsiy set the access Sme at 12ms

• Totally compatihle wilh all available disfc operating systems

• Degraded system Increased storage and speed S2B9 OO

VISTA DUALV-BO i

S670.00

THE VISTA V-200 FOR EXIDY

V200 E-20 400

woo E-22 aoo

WOOE-30 SID

ariinq as low as S 11 99.00

limit C»i il:|MI

CifKll Ci-IHinll

i"j';it;

MJJI=W=WI.VJJ=^J-VI.tY

TRS 80 16K-UPGRADE KIT

$49.95 TRS-80/APPLE $49.95

MEMORY EXPANSION KITS.

4116's, 16K (200/250 ns.)

8 pes for $49.95

w/instructions & jumpers

Call For Volume Pricing

* Special: TRS80 Schematic $ 4.95

* Expansion Interface Schematic .. S 4.95

* Expansion interface Connector... 7.95

EXPANDORAM II MEMORY KITS

* Bank Selectable * Uses 4116 200 ns.

• Wnte Protect nug* Power 8VDC. ±16VDC + Phantom «££si * Up to 4 MHz

Expando 64 Kil (4116) Assem. & Tested Add S50. 16K $249.00 48K S435.00 ^32K $289.00 64K S50S.O0

PERScfflSDEL^gT

DISKETTE DRIVE

3.2 Mbytes capacity (unformatted), max. seek time 100MS. ACP Price $2,199.00

rom^i " ~

Pmfcssiona1 Industrial Model

raser

Model UVS-11E $69.95

Holds 4 Eprom'a at a lime.

Backed by 45 years

experience.

ModelS-52T... $265.00

RAM BOARDS SPECIAL

16K AltalrMltB Dynamic RAM Boards Assam. & Tea tod S119.95 Untestod S95.00

16K

154300 '

M?taa )

193900

M

CENTRONICS PRINTER

Model 737

• Centronics complete printer

• The 737 has everything. Check and compare the features.

• New low price $835.00

The Vista V300 Printer

ATTENTION VIDEO HOBBYISTS!!!

* BOX BUILDERS

* USE AS REMOTE TUNER/TIMER

* FULL SCHEMATICS AVAILABLE

* FOR ONLY $5.90! - FREE W/PURCHASE

A Recent Soec.al Purchase Allows UsTo Present The Following

NEW, UNUSED COMPONENTS

From The RCA VDT-201 Vldeocissetle Recorder

I U»n/VHF Turcr Subj5armblyw,lhallkr»l>s

am Video DemcOu'.iror 559.95

? RF MorVa\v *i:nAuJo I VCeo incys

Chunrw 3D.4Duto.il S3B.95

Subtoi.il $123.34

** ' $74.95

re m 95 Call For Volume Discounts

LOW COST FLOPPY DISK SUBSYSTEM

Siemens FDD 120B (2) VISTA Floppy Controller (S- lOOl. Case. Power Supply S Cable. CP/M Disk Operating System Assembled a ToSIOd

Walnut Wood Sides S149B.0O

• CHECK OUR FlOPn DISK PRICING ON THIS PAGE* SAVE S300.00 IS1799.00 VALUE)

WATANABE MIPLOT

IMS STATIC RAM BOARDS

250 ns. 450 ns.

8K Static S209.00 S189.00

16K Sialic S449.00 ' S399.00

32K Sialic S729.00 S629.00

m£- SD SYSTEMS BOARDS

S* TAKE 10% OFF! kit a

SBC 100 Single SBC 200 Single ZBO Slailer Sys'

S285 00 299 00 31900 335 00 325 00 11500

i 34900 399 00 449 00 489.00 429.00 225 00 699500 7995 00

DESCRi S-ngie

Advanced Single BO Comp (68091 16 SlotMolher Board aid Cage

6600 MICROMODULE'" PRICE LIST

MODEL NO DESCRIPTION PRICE

9600A Single Board Micro com pule. S495 00

9609 Advanced Single BO Comp (68091 S9S.00

175 00 7 5 00 100 00 275 00 32500 39 OD 49500 490D 250 00

B Slot Mot

'. Suopiy

9627 9629

9629A 5 £10 9640 9650 9655 96103 96702

Senai-Parailel I/O Modui 16K Sialic; RAM Module 32K Stat.C RAM 450ns 32K Static RAM 200ns

32/32 I/O Module Contact Closure Module UNPOPULATED BOARDS rAiso *

250 o

39500

695 00 895 00 6B00 395 00 395 0 0 550 00 27500 350C0

I 5*,«(..fiM"w.

$189500

BASE II PRINTER

I5/230VAC.50

WITH ALL OPTIONS

EG S799.00

$699.

Z-80/Z-80A/8080 CPU BOARD

2708 included (450ns

* Power on jump * Completely socketed.

• Z-SO Assembled and Tosled

8080AKH

8080A Assembled..

. .S1B5.00 ...S12995 ...S 3495

.S 99.95

■ S1 49.95

S-100 MOTHERBOARD SPECIAL

8 slot expandable w/9 conn.

reg S69.95 NOW $52.95

SIEMEN'S FLOPPY

• Special buy while supply lasts.

• 8" Drive with Double-Density

• 90 Onv Warranty

♦ CHECK OUR FLOPPY DISK PRICING! ON THIS PAGE

SALE

SIEMENS S429.00 SHUGART

ACOUSTIC MODEM

'D'CAT MODEM

NOW AVAILABLE $199.00

Sanyo VM 4509

9"B/W 169.00

Sanyo VM 4212

15" B/W 249.00

Sanyo 6013

13" Color 42900

leede* 12" 149.00

NTEL Data Book

SALE • SYBEX COMPUTER BOOKS • SALE

rheZSO

IneZHOOO me 6502

FIRST TO OFFER PRIME PRODUCTS TO THE HOBBYIST AT FAIR PRICES!

1. PrOVen Quality Factory tested products only.

2. Guaranteed Satisfaction

3. Over $1,000,000.00 Inventory

1981 CATALOG AVAILABLE SOON.

Send $2.00 for your copy of the most complete catalog of computer products. A must for the serious computer user. MICROPROCESSORS

ZB001 16 bit 10 8Mb ., .SIB900 Z8002 16 bit I064K ,. . 149.00 ZBO 10.75

Z80A '* 60

FBI3850I 16.95

2650 .... . . 1895

C01802 1395

B080A . 850

B080A-4MHZ . 19 95

SALE SOBS 14 95

8008-1 . 1495

29°! 990

2901A 1495

29034.on Superette 2995

TMS9900JL 49 95

CP1600 . . , 3995

6502 H.50

65D2A 18 95

IM6100 . ... 29.95

680O 11.75

6800B2.0 MH* 1995

6S02P 17.95

8035 1995

8755 49 95

8748 6995

6809 , 37 95

8086 ... . ., .,,, .69 95

ADVANCED SUPPORT

AM9511 Arith. Processor 17 500

9512 A.itn Processor ... 17500

9513 Univ. Timing ,,.79 95

AM9517 DMA Controller ., 18 95 AM95!9UniversalinterruOI 189 5

Z-80 SUPPORT CHIPS

Z80-PIO 2 5MHI 8.75

ZBOAPIO 40 MHz ., 12.95

ZBO-CTC 25 MHr 8 75

ZBOA-CTC flOMHl.. . 12 95

ZBO-OMA 2.5 MHz 29.95

ZBOA-DMA 4 0 MHz 36 95

Z60-SIO/0 25 MHz.. .,,,. 35 95

Z80ASIO/0 4 0 MHZ 39 40

ZaO-SIO/1 2 5 MHz 3595

Z60A-SIO/1 40MHJ 39.40

Z60SIO/2 25 MHi. .. 35.95

Z60SIO/2 4.0MHz ..... 39.40

8080/8085 SUPPORT

6155/B156 I/O 2495

8755 l/Owith Erjrom 84.95

8202 Dyn Ram Cont 34.95

B205/74S 138 Decoder 3.95

82128 bit l/o 275

8214 Priority int. 5 25

6218 Bus Oliver 2.75

8224 Clock Gen 2.95

B224-4(4MH;) 9 75

8226 Bus D'iver . 3 95

BT26 Bus Dnvei 2 95

8228 Sys Control 5 50

B238SyS. Con! 5.50

8251. Piog. I/O 6 95

B2S3lnt Timer 12.95

8255 Prog I/O . 6 50

8257

.,,j C

825^1 Prog I

6800 SUPPORT CHIPS

6810 128 1 8 Ram. ,. 4.75

6B20 PIA 5.95

6821 PIA .... 650

8834-1 5>2 .8 Eororri . 16.95

6845/HD46505 CRT Cont.. , 39.9 5

6847 Color CRT 49 95

6B50ACIA ... 595

6852 Serial Adapter ,,.,, 5 95

6860 Modem .... . 10 95

6862 Modulalor ,11.95

6871A 1 OMHiOSC..... . .25.35

6d BO Eli-; Di MCB6483 68047

SHIFT REGISTER SALE

2528.. 2529.. 2533 .

6502 SUPPORT CHIPS

6520PIA. , 750

6522 Mult. .... 11.95

6530-002.003.004.005 .. 21.95 6532 . ... 19.95

6551 1995

PROMS

2708 460 ns. 625

2706-8 850 ns . ,,750

1702A . 4 95

2732 ... 74 95

271B-SV 14 95

2716 5V. 12V 19.95

2758-5V 19.95

5203AO ........ ... 13.95

5204AO 1495

IM 5810 . , 3 90

SALE 8223 32i 8 Z.95

62S115 512 . 8(TS1 . 16 95

82S12332 i9 4 90

82S128 256 1 4 4 90

B2S129256 < 4 (TSl 4 90

82S130 512 .4 (OCl 650

82S23 695

" 82S131 14 95

B2S137 14.95

NOTE: WE PROGRAM PROMS

CHARACTER GEN.

2SI3-O01 (5V)Uooer .... 9 50 2513-005 I5I.1) Lower .1095

2513-AOM3 15V) Lower 14 95

Cr.16571 M CM 657'

UARTS/BAUD RATE

COM 5016 ... . .16 95

KEYBOARD ENCODERS

AV5-350O

HD0155 74C922

13,75 13.75 9.95 9 95

STATIC RAMS

21L07 250ns I\t02

2,;;., \&

\ 1 30 1 25

'<?<)

| 1 59 '55 /375 1&5 2 95 2 8')

155

ail4L-8S0ns 146491

5 50

5 50 5 25

4044 450m

EMM420O* EMM440S

9'5 975

■■ 95

AM 03140AM

AMD9130/31

12 95 M95

1 96 175

6518 IK . 1 CMOS

7 95 7 95

'9 95 189

93415

9 95 8 95

TMS4046

11 q<". ,0Qf,

10 50

DYNAMIC RAMS

Seto'84ie~[

4995

f-r.r,

J 95 4 95

3 95 & 75

4 95

52S2 195 64K llDrm

-i

W70 495 RAMS 66Di 5230 4 9 5 ""„ 'X _ 6604 5290 .245$159.9560O7

7 95 1 50

SOCKETS

-Pins

Lo-Pro So Ids

\ WiilWrnc

Laval

:ail

18

19 2"

59

H4

22 26

38

75

1 20

36

1 25

40

60

ZERO INSERTION FORCE

16Pin E550 24 P,n ?7

:-.-.- ■:■"•■

= '■■■.'■■■

FLOPPY DISK I/O

0L7W 3

DL7D7 3

fN0357 3

FND501 5

F-\[!f>i»";;:ii! •■.

I'lGiC'.'.MDi '■

FND503 5 FMD530

FND550 ;ri(j5ijj!!i'.'j:

rNDSa/iBiOi

nP5tM2-73dO

■loc-; .'tlt. "*■;■?.■'■ ?7'n

TIL305

'.i:!i .j:ir-> inn r„\

Ciinun CJBW*

i:rvr.m r.i;i-.:rt' i:...r:-i Cjrrnli'

HL3DB TIL309

XAM306? V. Pi 3 063 >■/.!,!.: = .;

■A\3:ii

WNMM

..r.'nrsi

300 (tet Cornm

300 Grtcn Canm CgT

IC SPECIAL PURCHASE

LF 13508 JFET Analog Mulli 8 t) ICM 7045 Precision StooWatcH CMOS LED Sioowalcti/T.mer . . ICM 7207 Oscillator Controller Seven Decade Counter . .

1433P 3') Digit A/D C

L8211 I B50N Gro

,, p,......

1 95

3;i 00

\M 29O0N Quad Amni LM 2917N Freg to Won Con. 2/1 99

AV-3-3550 4'-.dig,l DMM . 2495

AV-5-3507 40MHz DUM 9 95

MEM 4983 Moslel Smohe DoledO' 1 1 95

27S0B3 2 . BPromnr.^ 56001 2 95

G115M 6 cr.annel MoMel 1 .19

111. N 2003A 7 channotDfivei 99

2101AL-4 1.95

MCM 14 505 84 bit Sialic Ram 8 95

MOC i003(4N2B)Ooio Couoler 3/100

SPX33 Oolo Counier 3/100

IH 5045 CMOS Sw.lch DBST 4.50

VA 3045 Trans Array 125

TR 1402AUADT . . 1 95

MR 1007 Dyn.Mem Stutt Reg 395

5736 Calc. Can Circuit. . 2/199

5763 Calc Con. Circuit '95

531Bl"VCt. Disn Circuit,.,, 4 50

aOBOABBitCPU ... . 495

B2S21 32 i 2 SlaticRAM . 2/1.99

B700 CJ B Sn A/D ... 9 95

27585V-2708 EPROM. .. 1295

MM52BOA/PO 4 11/C2 107/TMS4060/

4K>> Dynamic 22 Pm RAM 1 75

6604/VPD 414/4027/2660/MK 4096/

4K>1 Dynamic 16 Pin 1 95

7520/25 50 LM 3B7 1 25

3302

M323K 4 95

IC1372 895

IM529B-4A/Q 2 95

LM 4558 RC-H38 RC 4131 COM 5027 COM 5037 □ AClOO

3/1 99 2/1 99

VERBATIM DISKETTES

100% CERTIFIED ERROR-FREE!

uPd372 N

1 8" S Minilioopy . 24 95

Floppy 49 95

1781 Dual Floppy 29 95

1791-01 Dual Floppy 3695

jPd765Floooy 49 95

A/D CONVERTERS

1350

8700 B b.l Binary

8701 lObn Binary 8703 8 b.l IS 9400VOH ia Freo Co B7503'i Digit BCD

DACOI D 10 A 5g.

DACOB 99

DAC 100 ,.. 159

TV CHIPS/SOUND

AY38500 1 8 Games B/W 4 9

AY38515 CoiorCon^ener 29

AV38603-1 Roadrace Game 8 9 AV3B6081 WmeoulGame 9 5

AV3B607-1 Shooting Gallery 8 9

AY36910 Sound Generator 129

M&R t.

29 95

2 95

WAVEFORM GEN.

8038 Function Gen 3

MC4024VCO

LM566 VCO , . 1.95

XR2206 Function Generator 5 25

SHIFT REGISTERS

MM500H Dual25 50

MM5056N Dual 256 . ... 2.95

MM5050N Dual 128 2 95

2510A Dual 100 1 95

3351 40 ( 9 F

CTS DIPSWITCHES

CTS206-2 CTS206-4 CTS206-5 CTS206-6

CTS206-7 CTS206B CTS206-9 CTS206-10

CONNECTORS (GOLD)

DB25PIRS232) 3 25

DB25S Female 3 75

Set w/Hood Sale S7 50

22/44 WAV. S,T. KIM 2 95

43/86 WAV S/T. MOT 6 50

50/1COS-1O0 Connector w/w ,4 95

50/100S-100 Connector s/t 3 95

NAKED PC

S-100 Souno Board S34.95

Z-80 CPU/dlhacal .34,95

B080ACPU 34 95

16K Static RAM (21 14> . 29.95 32K Static RAM (2114) .. 39.95

BK Eorom(2708) 24 95

1702 Eprom Board 3000

270B/2716Eorom 34.95

Realtime Clock ..... .34 95

ACPProtoBd (3MConn) 27.95 Vector 6800 Prolo .. . , 2220 VeclorB803 11 slot MB .29 95 ACP Eitender w/Conn.. . 18 95 13 SiotMoiherBoa<d(WMC>3 2 95 9SiotMotherBoard(V,'MCI 29 95 BSIolMoiherlE.pandablel 34 95 Proc-Techi Bare Boards CALL

WMC Fmppy PCS 34 95

COMPUTER SPECIALS

PE1 2001E'ldySorc!

OHTS'

Pascal Microengme 1995 1 IPSt 1620DiabioRO 3295 2 Anade. DP 8000 995

Sanyo9-Mc Sanyo IS" hi

SOCKET SPECIALS

14 Pin W/H-2L 20P.nw/iv2L 16 Pin 5/1 22 Pin s/t

16 Pms/i

S 35 7 5

. . . 15

15

..100/12 00

. 100/1300

Call to: volume otici

Q

RETAIL STORES OPEN MON-SAT

P.O. Box 17329 Irvine, Calif. 92713

Direct Order Lines: (714) 558-8813

(800) 854-8230 or (800) 854-8241

FOREIGN Add 10V. shi andimg COD'sSI B5e<ii

FOR INTERNATIONAL ORDERS: 1310 E. Edlngor (714) 9530604

na,CA92705 TWX:910-595-1565

Circle 275 on Inquiry card.

BYTE March 1981

349

TERMINAL

DATA

CORPORATION

MODEL 1200 RS-232 BI-DIRECTIONAL DATA SPLITTER

available in kit form

Model 1200K gives the terminal or microprocessor user a second interface for a printer, plotter, cassette or tape drive. It operates at any speed & isolates the two outpul devices from each other, while providing 2 RS-232 interfaces from the terminal or microprocessor.

The kit consists of 3 RS-232 connectors, printed circuit board, all necessary components, enclosure, mounting hardware & assembly instructions $69.00

write or call

TERMINAL DATA CORP.

11878 Coakley Cir.

Rockville, MD 2DB52

(301) 881-7655

ATARI, OWNERS

SCREEN PRINT INTERFACE

Obtain hordcopy of any screen image (graphics and / or tent) on elltier a TRENDCOM 2O0 or IDS 440 Paper Tiger printer. Simply artach the supplied parallel printer coble and load the software from cassette (may be transferred to Disk). Obtain a "picture" of the screen on your printer under direct (CTRL?) or program (XIO) control. Works in all graphics / text modes as well as LPRINT and LIST "P" . - _ _

Only $139

Parallel Printer Interlace lor the ATARI 400 / 800

Connects to controller jacks 3&4 works with BASIC/DOS/ ASSEMBLER Three printer connectors available:

ATARI 400 /800 TRENDCOM100 / 200 A4P-1 ABP-1 CENTRONICS 730/737 A4P-2 A8P-2 CENTRONICS 36 PIN* A4P-3 A8P-3

95

69,

CA soles add 6% lax

MC / VISA accepted.

• Fits all other parallel CenlTonics plus Anadex, Base 2,

Epson, Comprint and Microtek. Older by port number,

ATARI is d recognizedtrodemork ot ATARI, Inc.

AMCROTRONICSJnc.®

1125 N. Golden Stale Blvd. / Suite G

Turlock. CA 95380 (A) (209) 667-2888 / 634-8888

Circle 276 on Inquiry card.

Circle 277 on Inquiry card.

for TRS-80 '

CUSTOM SOUND

A progratpablc SOUND GENERATOR for your computer.

Throe voices, e.icli capable of tones from subauili

anuUin"v*.luai" v"U"control,""-* "eyc^^thc

computer or by an internal envelope Boil critter,

All inputs arc latched, enabling the computer to

Trie device is capable of producing three

just octaves) as well as complex sound effects

(siicns, etc). All this at a fraction of the co

t

of comparable units, with the double cable, l«o

units can be "ganged" together to produce six

voices for your computer.

SOUND CCKCRATOK fc IT: (needs only

cable,5VIIC 6 speaker)

S49

two for

S80

CABLE: ritixin cable with PC edge connectors.

or Bx/lCT.

S20

double connector "

J25

SVOC REGULATED POKER SUPPLY :

fully assembled, 1.2 amp, OVP.

S23

comihc soon! SPEECH SYNTHESISER

computer controled phoneme generator

LNIUfttES WELCOME

/©UStom >»««f; «

\leripherals ^/ifS*

Box 8759 Warwick, Rhode bland 02888

" rcgestcrcd trademark, of Tandy Co rp.

Circle 278 on inquiry card.

DISK DRIVES

REMEX

Compatible with lBMand Shugart. Double sided, Double Density

1600 K Bytes.

RFD4000 S595

Double Sided, Double Density

800K Bytes

RFD2000 $395

For fast delivery, send certified checks, money orders or call to arrange direct bank wire transfers. Personal orcompanychecks require two weeks to clear. California Res. add 6% sales tax. Minimum shipping charge $10.00. No C.O.D. Electronic Equipment Unlimited 3845 Birch Street Newport Beach, CA 92660

PH: (714) 540-5231 Pricing and availability subject to change without notice.

SURPLUS ELECTRONICS

ASCII

ASCII

TRS-80* COMPATIBLE, IBM SELECTRIC® BASED I/O TERMINAL

with ASCII conversion installed: $645.00

Many Other Items Available: Tape Drives; Cable; Cassette Drives; Wire; Power Supplies (5 volt 35 amp, others); Displays; Cabinets; Transformers; Heat Sinks; Printers; Components.

Send for Free Catalog

WORLDWIDE ELECTRONICS, INC.

130 Northeastern Blvd.

Nashua, N.H. 03062

Phone orders accepted using VISA or MC

Toll Free 1-800-258-1036

in NH 603-889-7661

'TRS-80 is a trademark of the Radio Shack

Division of Tandy Corporation

Circle 279 on Inquiry card.

Circle 280 on inquiry card.

J and 5 CamputErs

2247 Shetland Road Livermore. Ca.94550

CENTRONIC PRINTER SALE

730-1 $617.00

730-3 SERIAL $654.00

737-1 $760.00

737-3 SERIAL $795.00

SCOTCH DISKETTES

740-0 8 INCH BOX OF 10 132 00

743-0 DOUBLE DENSITY/

DOUBLE SIDED BOX OF 1 0 $58 00

California residents add 6% sales lax Write for free catalogue

Circle 281 on inquiry card.

Special Offer! Limited "Time!

OWNERS 0fTRS-80Tlevelii,I6k

DERBYn

Outstanding game of racing designed by a scientist and statistician. Six mutual probability algorithms precisely coded (not just RNDl. Every race a cliff hanger. Bet to win place, or show; perfectos; trifectos! Photo finishes! Inquiries! Play different odds every race! Can be beaten with a lot of skill. I to 5 players, plus a lout who bets every race using exactly the same handicapping information you have (he will even place O bet for you-for a fee of course). Excellent spot graphics for realistic motion.

CAN YOU BEATtheTOUT

ORDER NOW for one of the most remarkable games you'll ever play. Only $15.00 (check or m.o.) for qual. cassette. Add $.50 postage, handling. FL res. odd 4% tax.

C8A ASSOCIATES, Inc.

RO. Box 23 6 2 Solellite Beoch, FL 32937

(VQ Check Your Options!

Sensors Available:

□ Temperature $ 64,95

□ Relative Humidity $82.95

□ Pressure $ 85.95

□ Magnetic Field S10895

Qlow Sensor $ 99.95

□ Light Level $ 49.95

□ Liquid Level S 78.95

□ LiveOb|ect $ 64.95

These Functions And More Available Off" The Shelf. . ."

systems

*- (602) 299-9831

'P.O. Box 35879 Tucson, Arizona 85740

16-BIT MC68000 CROSS-ASSEMBLER

w,:„En;n FORTRAN IV

hos now beer, added to our line of Hock FORTRAN crois -ossembler: lor Ine populor B fail microprocessors 16809. 6805. 6B0O, 8080/5. MCS6502 CDP1802) All of these emit assembler program* con be run on molt or, lor.,* or imoll computer intern ifiol support! standard FORTRAN IV. Pockages in dude new. exponded user i monuol, printed source lining, ond lDM> r'du

SOURCE MEDIA

CARD DECK PACKAGE !026or029 punch) SI25O0 5250 00 MAGNETIC TAPE PACKAGE (ASCII or

EBCDIC,IdOOor 800 bpi,blocked) $125.00 $250.00

MANUAL 8. LISTING ONLY S 50.00

Ml price! include shipping in the continental USA 10% disc = rde.s. 'Also available: M6800ta M680? Source cade Ire

'COMING SOON-Gois.assemblers in FORTRAN lor rhe i microprocessors: 8086, Z800Q,TM59?00 Send lor our Ire on assemblers, simulator!, ond othersoflware products.

IDM

Intelligent Devices of Mrt.

PO Bo*U538 Minneapolis Mn. 55414 (612) 427-0787 7AM-12Noon

Circle 283 on inquiry card.

Circle 284 on inquiry card.

DIGITAL RESEARCH COMPUTERS

(214)271-3538

32K S-100 EPROM CARD NEW!

Blank PC Board - $34

ASSEMBLED & TESTED ADD $30

SPECIAL: 2716 EPROM's (450 NS) Are $11.95 EA. With Above Kit.

KIT FEATURES: 1- Uses +5V only 2716 (2Kx8) EPROM's.

2. Allows up to 32K of software on line!

3. IEEE S-100 Compatible.

4. Addressable as two independent 16K blocks.

5. Cromemco extended or Northstar bank select.

6. On board wait state circuitry if needed.

7. Any or all EPROM locations can be disabled.

8. Double sided PC board, solder-masked, silk-screened.

9. Gold plated contact fingers.

10. Unselected EPROM's automatically powered down for low power.

11. Fully buffered and bypassed.

12. Easy and quick to assemble.

32K SS-50 RAM

$379

00

KIT

For 2 MHZ Add $10

Blank PC Board $50

For SWTPC 6800 - 6809 Buss

Support IC's

and Caps

$19.95

Complete Socket Set

$21.00

Fully Assembled,

Tested, Burned In

Add $30

At Last! An affordable 32K Static RAM with full 6809 Capability.

FEATURES:

1. Uses proven low power 2114 Static RAMS.

2. Supports SS50C - EXTENDED ADDRESSING.

3. All parts and sockets included.

4. Dip Switch address select as a 32K block.

5. Extended addressing can be disabled.

6. Works with all existing 6800 SS50 systems.

7. Fully bypassed. PC Board is double sided, plated thru, with silk screen.

16K STATIC RAM KIT-S 100 BUSS

16K STATIC RAM SS-50 BUSS

PRICE CUT!

$1999„51T

L)tJ^lM^diifuuu£aJ

7$i I II III 1:1 111 IIP ■

.|i i.i iiWiiiii'■'■.!■«

PRICE CUT!

mm

$195

KIT

Illlilillllillll

S 1 Ml 83 S I I i I 11:1111

KIT FEATURES:

1. Addressable as four separate 4K Blocks.

2. ON BOARD BANK SELECT circuitry. (Cromemco Standard1). Allows up to 512K on line!

3. Uses 2114 (450NS) 4K Static Rams. 4.- ON BOARD SELECTABLE WAIT STATES.

5. Double sided PC Board, with solder mask and silk screened layout. Gold plated contact fingers

6. All address and data lines fully buffered. ASSEMBLED & TESTED-ADD $35

7. Kit includes ALL parts and sockets.

8. PHANTOM is jumpered to PIN 67.

9. LOW POWER: under 1.6 amps TYPICAL from the+8 Volt Buss.

10. Blank PC Board can be populated as any multiple of 4K.

BLANK PC BOARD W/DATA-$33

LOW PROFILE SOCKET SET-$12

SUPPORT IC'S & CAPS-$19.95

FOR SWTPC 6800 BUSS!

OUR#1 SELLING RAM BOARD!

KIT FEATURES:

1. Addressable on 16K Boundaries

2. Uses 2114 Static Ram

3. Fully Bypassed 4 Double sided PC Board. Solder mask

and silk screened layout.

5. All Parts and Sockets included

6. Low Power: Under 1.5 Amps Typical

BLANK PC BOARD—$35 COMPLETE SOCKET SET—$12

SUPPORT IC'S AND CAPS—$19.95

ASSEMBLED AND TESTED - $35

^ STEREO! »w

S-100 SOUND COMPUTER BOARD

COMPLETE KIT! $3495

(WITH DATA MANUAL)

At last, an s-100 Board that unleashes the full power of two unbelie/able General Instruments AY3-8910 NMOS computer sound IC's. Allows you under total computer control to generate an infinite number of special sound effects for games or any other program. Sounds can be called in BASIC, ASSEMBLY LANGUAGE, etc. KIT FEATURES:

* TWO Gl SOUND COMPUTER IC'S.

* FOUR PARALLEL I/O PORTS ON BOARD

* USES ON BOARD AUDIO AMPS OR YOUR STEREO.

* ON BOARD PROTO TYPING AREA.

* ALL SOCKETS, PARTS AND HARDWARE ARE INCLUDED . PC BOARD IS SOLDERMASKED, SILK SCREENED. WITH GOLD CONTACTS.

* EASY, QUICK, AND FUN TO BUILD. WITH FULL INSTRUCTIONS.

* USES PROGRAMMED I/O FOR MAXIMUM SYSTEM FLEXIBILITY. Both Basic and Assembly Language Programming examples are included

SOFTWARE: SCL™ is now available! Our Sound Com mand Lan guage makes writing Sound Effects programs a SNAP! SCL™ also includes routines fo r Register-Examine-Modify. Memory-Examine-Modify, and Play-Memory. SCL™ is available on CP/M* compatible diskette or 270B or 2716. Diskette ■ J24.9S 2708 - S19.95 2716 - S29.9S. Diskette includes the source. EPROM'S are ORG at EOO0H.

BLANK PC

BOARD W/DATA

$31

4K DYNAMIC RAM BLOWOUT!

SAME AS INTEL 2107B!

4K RAMS AT AN UNBELIEVABLE 504 EACH!!!

Prime, new. National Semi., 1979 date coded, full spec, parts. N.S. *MM5280-5N. Same as INTEL 2107B-4, T.I. TMS4060. NEC uPD411. etc. We bought a HUGE QTY. from a West Coast Distributor at truly DISTRESS PRICES! One of the most popular and reliable RAM's ever made. These parts have been used by almost all Major Computer Main Frame Mfg. the world over! Arranged as 4K x 1, 270 NS Access Time. 22 Pin Dip. These units DO NOT use multiplexed addressing, thus making REFRESH and other timing very simple. See INTEL MEMORY DESIGN HANDBOOK for full application notes. The NAT. SEMI. MEMORY DATA BOOK is available at most Radio Shack Stores. Prime units in original factory tubes!

#5280-5N 4096 BITS x 1 270 NS ACCESS

8 FOR $4.95 32 FOR $16

FACTORY CASE (450 PCS) — $180

Sockets Special: 22 Pin Low Profile (With Purchase of 5280's) 8 FOR $1.

COMPUTER PARTS SPECIALS

74LS175- .99 8035 Intel Single Chip CPU 6.95

74LS240 - 1.19 Signetics 2901 4 Bit Slice - 6.95

74LS241 - 1.19 AMD 2903 4 Bit Super Slice - 12.50

74LS244 -1.19 AMD 29705 Dual Port RAM - 8.95

74LS373 - 1.29 Intel 2716-1 (350 NS) - 12.95

NEW! G.I. COMPUTER SOUND CHIP

AY3-8910. As featured in July, 1979 BYTE! A fantastically powerful Sound & Music Generator. Perfect for use with any 8 Bit Microprocessor Contains:3ToneChannels, Noise Generator, 3 Channels ofAmplitude Control. 16 bit Envelope Period Control, 2-8 Bit Parallel I/O. 3 D to A Converters, plus much more! All in one 40 Pin DIP. Super easy interface to the S-100 or other busses. $11.95 PRICE CUT!

SPECIAL OFFER: $14.95 each Add $3 for 60 page Data ManuaL

L

Digital Research Computers

** (OF TEXAS) '

P.O. BOX 401565 » GARLAND, TEXAS 75040 « (214) 271-3538

TERMS: Add $1.50 postage. We pay balance. Orders under $15 add 75C handling. No C.O.D. We accept Visa and MasterCharge. Tex. Res. add 5% Tax. Foreign orders (except Canada) add 20% P & H. Orders over $50, add 85C for insurance.

I

•TRADEMARK OF DIGITAL RESEARCH.

WE ARE NOT ASSOCIATED WITH DIGITAL RESEARCH OF CALIFORNIA. THE SUPPLIERS OF CPM SOFTWARE.

BYTE March 1981 351

Know The Reasons Why

The FORCE-80 is your

"Best Buy."

FORCE-80 The computer protector

• Power dropout protection

• Suppresses transient voltages

• Suppresses RFI

• Disc protection

• Factory warranty

• Satisfaction guaranteed

• Direct from factory

FORCE-80

Only $121.50 plus $5.00 shipping & handling

Check, Mastercharge, Visa accepted (5% discount for cash) ^^^m No C.O.D.'s please JJJ^

P&S Electronics, Inc.

P.O. Box 23014 Dept. B Nashville, TN 37202

Allow 6-8 weeks for delivery. Add 14 days lor personal checks.

STATISTICAL SOFTWARE

The Winchendon Group announces its powerful statistical system which includes a database system, all BASIC transformations, simple statistics, stepwise regression, correlation, crosstabs, factor analysis and more.

Now available for the Apple II + *, 48k with DOS 3.2.1*. $ 1 50, for the complete version.

Write for further information.

P.O. Box 10114 Alexandria, Va. 22310

'Apple 11+ and DOS 3.2.1 are trademarks of the Apple Computer Company

!!!PROGRAMMERS!!!

$ $ $ $

TURN YOUR WILDEST IMAGININGS INTO CASH $SS. WE'RE LOOKING FOR NEW CONCEPTS IN COMPUTER VIDEO GAMES AND WE'RE WILLING TO PAY PROGRAMMERS TOP PRICES FOR ORIGINAL IDEAS. SUBMIT A WORKING PROTOTYPE TO:

MR. DOMINIC SANZO

GAME-A-TROM CORP.

931 WEST MAIN ST.

NEW BRITAIN, CT. 06051

CALL 1-203-223-2760 FOR FURTHER INFORMATION

_GAME

^^T IDEAS WANTED

GAMEA-TRON

Circle 285 on inquiry card.

Circle 286 on inquiry card.

PRINTERS

NtW BASE, MODEL 8SO WTJ799 OUR PRICES 73 S

BASE, MODEL 800B mt stn OUR PRICE SS8S

NEW BASE,/APPLE GRAPHICS

INTERFACE

uiTiittOUR PRICES 140

0KIDATA i> LINE 80 tursMoOUR PRICE $550

•PllASt ADO 3% fOR Sin TO OKDED* SCNDFOK IHI0SMAJI0H ON 0U8 OTHIS PSODUCTUMS

I

TECHNICAL INNOVATIONS P.O. BOX 803 DEPT B2 HILISB0R0, OR 97123

503-648-6423

I

SOFTWARE DESIGN ENGINEER

BSEE/BSCS. minimum 3 years programming experience. Realtime systems programming and software development for electronic switches is a plus. Experience with PASCAL or C or Assembly language required. Call collect or send resume to Kenneth W. Cooper, Harris Corporation, RF Communications Division, 1680 University Avenue, Rochester, NY 14610, (716) 244-5830, EXT 3356.

HARRIS

An Equal Opportunity Employer M/F

siyvvv

MEMOREX

Floppy Discs

Lowest prices. WE WILL NOT BE UNDERSOLD!! Buy any

quantity 1-1000. Visa Mastercharge accepted Call free (800)235-4137 for prices and information. All orders sent postage paid.

PACIFIC EXCHANGES

100 Foothill Blvd. San Luis Obispo. CA 93401. (InCal. call (805)543-1037.)

Circle 287 on inquiry card.

Circle 288 on inquiry card.

Circle 289 on Inquiry card.

Save up to 50%

using our buying power. We buy over three million dollars of computer equipment wholesale per year for clients who range in size from the largest manufacturers to the home hobbyist. Our fee is one fourth of what we save you off the manufacturer's suggested list price, so it is to our advantage to save you money.

THE PURCHASING AGENT

1635 School Street, Suite 101 Moraga, CA 94556 (415) 376-9020

COMPUTERS

c1p series ii - $479.00 our price - $399.00

other OSI discounts available

CALL NOW TOLL FREE

1-800-558-0870

COMPUTERS PLUS, INC.

2749 S. 1DBth St. MILWAUKEE. Wl 53227

[414] 321-1770

IN WISCONSIN

EXOTIC BASIC PROGRAM

BATTLE FOR

GAMMA OMICRON

OUTPOST #1

(a game in the tradition of great

star battles in space)

$2 postage and handling for

listing

* EXTRA BONUS LISTING: *

* LAS VEGAS BINGO PIN-BALL *

* (card simulation) # *************

bonus offer expires March 31, 1981

THE COMPUTER SOCIETY

P.O. BOX 1056 WASHINGTON PARK, IL. 62204

Circle 290 on Inquiry card.

Circle 291 on inquiry card.

Circle 292 on inquiry card.

1858 Evergreen Street,

Duarte, California 91010

^^Ki

Phone 213-357-5005

page

DIGITAL INC. If

INSULATION DISPLACEMENT SOCKETS

RIGHT ANGLE HEADERS

Pins 10 20

26 34 40 50

PC Mounting WtraWrap

IDH10SR .80 IDH10WR 1.75 IDH20SR1.25 IDH20WR 2.75 IDH26SR 1.85 IDH26WR 3.60 IDS34SR 2.15 IDH34WR 4.15 IDH40SR 2.50 IDH40WR 4.90 IDH50SR 3.15 IDH50WR 6.15

EJECTOR EARS .25 EACH

25 PIN "D" CONNECTORS

«-*v

;''<•

Styto Part •

SOLDER STYLE Male DB25P .2-25 Female DB255 3.00 Hood DB25C 1.10

INSULATION DISPLACEMENT Male IDC25P 4.95 Female IDC255 5.25 Hood IDC25C 1.35

CARD EDGE CONNECTORS

Plnj

Part No.

10

IDE10

3.25

20

IDE20

3.50

26

IDE26

4.05

34

IDE34

4.B5

40

IDE40

5.65

50

IDE50

5.90

SOCKETS

Pins

10 20 26

34 40 50

Part No. IDS10

IDS20 IDS26 IDS34 IDS40 IDS50

1.25 2.02 2.65 3.50 4.05 5.06

Stain Sttli.1

.25

.25

.25

.25

.25

.25

Conductors: Solid Color

Color Coded

10 14 16 20 24 26 34 40 50

10 ft.

2.90 3.40 3.70 4.40 5.00 5.40 6.80 7.80 9.50

too It. 17.00 23.80 27.20 34.00 40.80 44.20 57.80 68.00 85.00

10 n.

4.00

5.00

5.60

7.00

8.00

8.60

11.00

13.00

16.00

too II.

30.00

42.00

48.00

60.00

72.00

78.00

102.00

120.00

150.00

CABLE PLUGS

Pins 14 16 24 40

Pait No.

IDP14 1.25

IDP16 1.40

IDP24 IDP40

2.25 3.65

WIRE WRAP WIRE

WIRE KITS

Length 100/Bag

500/Bag 1 K/Bag

Length 100/Bag 500/Bag

1 K/Bag

Kit No. 1

$9.95

Kit No. 3

$32.95

2.5" $1.25 3.0" 1.30 3.5" 1.37 4.0" 1.42 4.5" 1.48 5.0" 1.54 5.5" 1.58 6.0" 1.65

$3.58 $ 6.19 3.86 6.78 4.15 7.37 4.44 7.94 4.74 8.54 5.04 9.13 5.38 9.72 5.66 10.31

6.5" $1.92 $6.44 7.0" 1.99 6.76 7.5" 2.08 7.07 8.0" 2.14 7.38 8.5" 2.18 7.69 9.0" 2.24 8.11 9.5" 2.30 8.32 10.0" 2.39 8.71

$11.81 12.44 13.09 13.73 14.36 15.01 15.65 16.28

250 250 100

3"

3W

4"

100 100 100

4Va"

5" 6"

500 2 '/*• 500 3" 500 3%' 500 4"

500 4%" 500 5" 500 5'/2" 500 6"

Kit No. 2

$24.95

Kit No. 4

$59.95

250 500 500 500 250

2</s"

3"

3'/*"

4"

AW

250 100 250 100 100

5"

5Vi"

6"

6V4"

7"

1000 2%' 1000 3" 1000 3'/a' 1000 4"

1000 4V2" 1000 5" 1000 5" 1000 6"

Kynar precut wire. AH lengths are ov Colors and lengths cannot be mixed tc Red, Blue, Black, Yellow, White, Gre

erall, including 1" strip on each end. r quantity pricing. Choose from colors en, Orange, and Violet.

ORDERING INFORMATION:

• Orders under $25 include $2 handling

• All prepaid orders shipped UPS Ppd.

• Visa, MC & COD's charged shipping.

• All prices good through cover date.

• Most orders shipped same day.

• Byte must be mentioned to get sale price.

Write or call for 1981 catalog

• IC Sockets

• Vector Board & Pins

• Bishop Drafting Aids

• OK Tools

» RN IDC Crimp Connectors

"NEW" WIRE WRAP SOCKETS

FEATURING A SELECTIVE PLATING METHOD THAT WILL SAVE YOU MONEY BY HAVING GOLD ONLY WHERE IT COUNTS.

GOLD PLATED CONTACTS

TIN PLATED TAILS

3 Level closed entry.

RN Side Wipe contact design gives twice the contact area for high reliability.

Size

8

Quantllv/Tube 52

Price ea.* .41

Price/Tube 21.32

14

30

.47

14.10

16

26

.51

13.26

18

23

.70

16.10

20

21

.87

18.27

22

19

.94

17.86

24

17

.96

16.32

28

15

1.25

18.75

40

10

1.70

17.00

•FOB REFERENCE. MUST BE ORDERED IN TUBE QUANTITIES.

Circle 294 on inquiry card.

TOLL FREE ORDERING NUMBER 1-(800)-423-7144

Eleusis and The TI-59

Your TI-59 can now act as God (well, dealer) in the New Eleusis (the card game introduced in the October 1977 Scientific American). The Eleusis-Dealer program randomly chooses a rule then accepts or rejects the cards played.

To obtain magnetic cards for the program, along with documentation, Eleusis instructions, and the latest newsletter, send $6 to

Robert Abbott

Box 1175, General P.O. New York, NY 10116

>*»

Skylcs Electric Works

231 E South Whisman Road Mountain View, CA 94041

"Attention Computer Owners"

If you own a mini or micro... you could be on your way to fantastic riches. Put your computer to a new use by monitoring real estate investments. Set up your own office in your home...never work for the other guy again. It is the most ingenious program ever devised. Make six digits annually.

First time offered. Complete package—$36.00. We pay postage & handling. Send check or M.O. to:

C.B.A.S.

P.O. Box 163 Ontario, OH 44862

Circle 295 on inquiry card.

Circle 296 on Inquiry card.

LETTER QUALITY

DAISY WHEEL PRINTER $2,195.00

* Based on latest version of electronic typewriter by Olivetti, Ltd.

* Use offline as typewriter

* RS232C Interface Standard

* Over 200 words per minute

* 10, 12 &. 15 C.P.I.

* International Type Fonts

* Available Immediately Money order or C.O.D. to:

Vertical Data Systems, Inc

1215 Meyerside Dr., Unit 2A

Mississauga, Ontario, Canada

L5T 1H3

(416)671-1752

A ATARI"

COMPLETE LINE OF ATARI COMPUTER PRODUCTS 20-25% OFF

Atari 800 with I6K $810 Atari 610 Disk Drive. $460

Atari 400 with 8K $399 Atari 410 Cassette Player. $69

Vlsicalc $170 Kurla Graphics Tablet $560

Ramcram 32K Modules (upgrade 400 or 600) $256

ALL ATARI SOFTWARE 20% OFF BIT BUCKET SOFTWARE FOR ATARI: Utilities Disk with Disassembler, Basic Renumberer, Character Generator, Cruncher

Utility (requires 24K) S45

Games: Mastercode, Mr. Simon, City

Bomber (each) $12.95

Hex, Cryptogram,

Flying Saucers (each) $14.95

Any 3 Of above $30.00. (specily disk or cassette)

ALSO: Commodore Pet at Similar Savings PLUS: Centronics, NEC, Zenith, Intertec, and More!

The Bit Bucket

Hardware. Software. Consulting 168 North Beacon Street .P.O. Box 365

Newton Highlands. MA 02161 Phone:(617) 783-3144

EVERY MONTH

BUY, SELL OR TRADE ALL TYPES OF COMPUTER EQUIPMENT AND SOFTWARE (pre-owned and new) among 20,000 readers nationwide in BIG (11x14") pages. Classified ads are only 10' per word and are indexed for easy and fast location. Subscription: $10 a year/12 issues. Money back guarantee. Sample copy, $1.50. campurea SHOPPSR

P.O. Box F-14

Titusville, FL 32780

(305)269-3211

MasterCard or VISA subscription orders only,

call TOLL FREE 1 BOO 528 6050 Ex. 184.

Circle 297on Inquiry card.

Circle 298 on Inquiry card.

Circle 299 on inquiry card.

□ YES I Sign me up as a charter subscriber. Enclosed is my $20.00 for 10 issues. C$24 to Canada. $30 elsewhere.)

D Not sure. Enclosed is $2 for a sample issue.

Circle 300 on Inquiry card.

You may be in danger of spending almost $200 for a so-called FORTH' system that is not interactive!

Timin FORTH has a memory resident editor and a virtual memory subsystem, as well as all the features of true FORTH.

Our heavily advertised f^Sr™]

competitor does not!

Place your order today— (

then go FORTH and conquer!

■InrCP/M IDigit.il K.-M-.ird, ( cir|i ]

Q.'O MITCHELL E. TIMIN

Q O 0 ENGINEERING COMPANY

OO 9575 GENESEE AVENUE- SUITE E2 V\J SAN DIEGO. CALIFORNIA 92121

714-455-9008

Circle 301 on Inquiry card.

MICROPROCESSOR SUPPORT IX.'S 1

WE GUARANTEE FACTORY PRIME PARTS |

We are going to become

the largest supplier of prime

NEC 16Kx1 DYNAMIC RAM 200 N.S.

microprocessor support I.C.'S. We guarantee that our I.C.'S are purchased from manufacturer authorized distributors. This is the only way to deliver prime parts at the lowest

These are prime 4116 's from one of the MOS RAM manufacturers in the world.

best

possible prices. Our committment is to offer the best price and the fastest delivery to our customer. We give many

4i id zuuns 8 for $25.00 32 for 96.00

thanks to our valued customers who have helped us grow.

Only prepaid orders on this special.

8080A CPU

4.95

2708 EPROM 1Kx8 4.95

NEC 1Kx4 STATIC RAM 250 N.S.

8085A CPU

8.95

2716 EPROM 2Kx8 8.95

These

are prime low power static ram's

NEC

8086 CPU

99.95

2732 EPROM 4Kx8 21.00

for the finest in MOS MEMORY.

8088 CPU

44.95

4118 STATIC 1Kx8 15.00

2114L 250ns

Z-80 CPU

10.50

4164 200ns 64Kx1 Call

8 for $25.00 32 for $96.00

Z-80A CPU

12.95

Z80B CPU 21.00

Only prepaid orders on this special.

Z80-P10 7.75

8289 '

19.95

4050 .69

4531

.99

74C925 6.95

74LS107 .45

74LS244

1.95 I l

Z80A-P10 9.75

4000

.35

4051 1.10

4532

1.25

74LS00 .35

74LS109 .45

74LS245

4.95 I !

Z80-CTC 7.75

4001

.35

4052 1.10

4539

.99

74LS01 .28

74LS112 .49

74LS247

1.10 1

Z80ACTC 9.75

4002

.35

4053 1.10

4543

1.99

74LS02 .28

74 LSI 22 .55

74LS248

1.10 1

Z80-DMA 22.25

4006

1.39

4055 3.95

4553

3.50

74LS03 .28

74LS123 1.19

74LS249

1.69 I

Z80A-DMA 27.75

4007

.29

4056 2.95

4555

.75

74LS04 .39

74LS125 1.35

74LS251

1.79 1

Z80-S10/0 24.95

4008

1.39

4059 9.95

4556

.75

74LS05 .28

74 LSI 26 .89

74LS253

.98 1

Z80A-S10/0 29.95

4009

.49

4060 1.39

4581

1.99

74LS08 .39

74LS132 .79

74LS257

.98 1

Z80-S10/1 24.95

4010

.49

4066 .75

4582

1.01

74LS09 .39

74LS136 .59

74LS258

.98 1 ]

Z80A-S10/1 29.95

4011

.35

4068 .35

4584

.55

74LS10 .28

74 LSI 38 .89

74LS259

2.95

Z80-S10/2 24.95

4012

.29

4069 .35

4585

.99

74LS11 .39

74LS139 .89

74LS260

.69

Z80A-S10/2 29.95

4013

.49

4070 .49

4702

9.95

74LS12 .39

74LS145 1.25

74LS261

2.49

3205 3.45

4014

1.39

4071 .35

74C00

.39

74LS13 .47

74LS148 1.49

74LS266

.59

3242 10.00

4015

1.15

4072 .35

74C02

.39

74LS14 1.25

74LS151 .79

74LS273

1.75

8155 11.25

4016

.59

4073 .35

74C04

.39

74LS15 .39

74LS153 .79

74LS275

4.40

8185 29.95

4017

1.19

4075 .35

74C08

.49

74LS20 .26

74LS155 1.19

74LS279

.59

8185-2 39.95

4018

.99

4076 1.29

74C10

.49

74LS21 .38

74LS156 .99

74LS283

1.10

8202 45.00

4019

.49

4078 .35

74C14

1.65

74LS22 .38

74LS157 .99

74LS290

1.29

8205 3.45

4020

1.19

4081 .35

74C20

.39

74LS26 .39

74LS158 .75

74LS293

1.95

8212 2.00

4021

1.19

4082 .35

74C30

.39

74LS27 .39

74LS160 .98

74LS295

1.10

8214 3.95

4022

1.15

4085 1.95

74C32

.99

74LS28 .39

74LS161 1.15

74LS298

1.29

8216 1.85

4023

.38

4086 .79

74C42

1.85

74LS30 .26

74LS162 .98

74LS324

1.75

8224 2.65

4024

.79

4093 .99

74C48

2.39

74LS32 .39

74 LSI 63 .98

74LS347

1.95

8226 1.85

4025

.38

4099 2.25

74C73

.85

74LS37 .79

74LS164 1.19

74LS348

1.95

8228 5.00

4026

2.50

4104 1.99

74C74

.85

74LS38 .39

74LS165 .89

74LS352

1.65

8238 5.45

4027

.65

4501 .39

74C85

2.49

74LS42 .79

74LS166 2.49

74LS353

1.65

8243 4.65

4028

.85

4502 1.65

74C89

4.95

74LS47 .79

74LS170 1.99

74LS363

1.49

8251A 5.55

4029

1.29

4503 .69

74C90

1.85

74LS48 .79

74LS173 .89

74LS365

.99

8253 9.85

4030

.45

4505 8.95

74C93

1.85

74LS51 .26

74LS174 .99

74LS366

.99

8255A 5.40

4031

3.25

4506 .75

74C95

1.85

74LS54 .35

74LS175 .99

74LS367

.73

8255A-5 5.40

4032

2.15

4507 .95

74C107

1.19

74LS55 .35

74LS181 2.20

74LS368

.73

8257 9.25

4033

2.15

4508 3.95

74C151

2.49

74LS73 .45

74LS190 1.15

74LS373

2.75

8257-5 9.25

4034

3.25

4510 1.39

74C154

3.50

74LS74 .59

74LS191 1.15

74LS374

2.75

8259A 7.30

4035

.95

4511 1.39

74C157

2.10

74LS75 .68

74LS192 .98

74LS375

.69

8271 60.00

4037

1.95

4512 1.39

74C160

2.39

74LS76 .45

74LS193 .98

74LS377

1.95

8275 32.95

4040

1.29

4514 3.95

74C161

2.30

74LS78 .65

74LS194 1.15

74LS385

1.95

8279 10.80

4041

1.25

4515 3.95

74163

2.39

74LS83 .99

74LS195 .95

74LS386

.65

8279-5 10.80

4042

.95

4516 1.69

74164

2.39

74LS85 1.19

74LS196 .89

74LS390

1.95

8282 6.70

4043

.85

4519 .99

74173

2.59

74LS86 .45

74LS197 .89

74LS393

1.95

8283 6.70

4044

.85

, 4520 1.39

74174

2.75

74LS90 .75

74LS221 1.49

74LS395

1.70

8284 5.85

4046

1.75

4522 .99

74C175

2.75

74LS92 .75

74LS240 1.95

74LS399

2.95

8286 6.70

4047

1.25

4526 1.15

74C192

2.39

74LS93 .75

I 74LS241 1.90

74LS424

2.95

8287 6.70

4048

.99

4527 1.75

74C193

2.39

74LS95 .88

74LS242 1.95

74LS668

1.75

8288 25.40

4049

.69

4528 .99

74C195

2.39

74LS96 .98

74LS243 1.9 5

74LS670

2.29

! MAIL I P.O. Be

Telephc

ORDERS >x 21432

>ne Order

SHOULD BE SENT TO: Seattle, Washington 98111

5 & Inquiries (206) 453-0792

HANLEY ENGINEERING

RETAIL STORE 1644 116th NORTHEAST

I Minimu

m Order

$10.00 Add $3.00 Shipping

_

BELLEVUE, WASHINGTON 98005

| FOR T

HE Fl

NEST IN MICROPRO*

CESSOR SUPPORT I.C

s

Circle 304 on inquiry card.

BYTE March 1981

355

10,000 WORDS IN 1 MINUTE, PROOFREAD FOR SPELLING

20,000 word user expandable dictionary, easy to use, Requires CP/M* 8080/ Z80 with 32K memory. Compatible w/ Magic Wand*,WordStar*,Electric Pencil* and many others. $269.00

New Crystal-Clear* Operator's Training Manual for Magic Wand* and related CP/M* is designed for the secretary and noncomputerist use. Dual column pages present instructions and explanationson left, drawings, pictures & screen displays on right. Small black circles precede user action steps for clarity and quick future reference. $35.00

Free Crystal-Clear * Operator's Training Manual with Magic Wand * customized for your CPU, terminal, Printer & disk. $299.00

PELICAN PROGRAMS

*Trademark

Pelican Programs 49 Pelican Court, Syosset, N.Y. 11791

SMARTNET

| printer)-—

SATELLITE COMPUTER

HUB COKHITERI

J DISK |

SATELLITE COMPUTER

|terkii:al| features

-Automatic spooling and despooling. -Levels 1-15 of the hub computer are

password protected. -No modifications needed to the BIOS

or XI0S. -Block data transfer with checksum. -Low memory requirements. -Complete source code provided.

REQUIREMENTS

-Hub computer must be running RP/K , -Smartnet requires CP/K* 2.2, 20k of

memory and at least one disk drive. -Dumbnet requires at least 16k of

memory. Disk drives not needed,

PRICE

SMARTNET .5150.00 DUMBNET .1175.00

PURCHASE TOGETHER 3500.00

LIHI-IAR

541 Ingraharn Ave.

Calumet City, IL. 60409

312-868-4866 Ask for Mark

* Trademark of Digital Research.

SUBMINI DPDT DIP RELAY

AROMAT #HB2-DCfiV

jjfefl '6 VDC co"'Flls dip '''-'-■'

h«j -Nofm power 5B0 mW

^^HP . Contacts raled @ 120V

'^Sl.50each i0iorSi3S0

40 PIN RT ANGLE P £ .B .

mum HE

JiJtttt«H*W*l-pHINTED CIRCUIT ^"" RIGHT ANCLE

Jl .50 EACH mount

40 PIN RIBBON CABLE SOCKET CONNECTOR

22/44 EDGE CONNECTOR

TIN SOLDERTAIL .156"x .200'

LARGE QUANTITIES AVAILABLE S1.35each 10tOfS12.50

7-17vdc S.S. BUZZER

CMOS compdlib

$1.25 each

FLAT LEVER HANDLE (/'MINI TOGGLE

SPOT RATED

6 AMPS [SI 125 V /4 - 40 BUSHING

51,00 each

10 lor SB 50

Litronix FRL-4403

FLASHER

A LED

W dillused red lad

^Pwllh built in Mashing unit

ALL CLECTROniCS CORP.

905 S. Vermont Ave. terms

Los Angeles, Calif. 90006 (213)380-8000 Mon.-Fri. Saturday 9 AM -5 PM 10 AM

SEND FOR FREE CATALOG

Quantities Limited Min.OrderSlO.OO Add $2.00 Shipping USA 3 PM • Calif. Res. Add 6% Prompt Shipp'

Circle 305 on inquiry card.

Circle 306 on inquiry card.

Circle 307 on inquiry card.

$94.20*

Single Board Computer

j^isgii.

Mlik|

11111°

"100 piece price, model MCL11

6800 MPU, serial I/O, parallel I/O, RAM, EROM, 44-pin 4VS'-x 6W' PCB

EXPANSION MODULES RAM, ROM, CMOS RAM/battery, analog I/O, serial I/O, parallel I/O, counter/ timer, 488 GPIB, EROM programmer, power tail detect/power on reset

UT|V'l1l7lr I 1801 South Street i ■ k» I I j Ik. Lalayette, IN 47904

SPELLING

eliminated with

SPELLGUARD™

Proofreads 100 pp. per minute with Wordstar or Magicwand.

Spcllguard

Wordstar w/Spellguard

Magicwand w/Spellguard

$295

$325 $585

$275 $510

TPA

1635 School St. Moraga. CA 94557 415) 376-3753

WANTED I

v^*-»

The Blacksburg Group wants to evaluate your software for publication in the Blacksburg Continuing Education Series (Howard W. Sams and Co.) We're interested in circuit design, scientific application and data handling programs, among others. Please send us acopy of your orginia/ software, with documentation for our review. We'll send you a complete author kit. Competitive advances & royalities. All software treated as confidential. Let's see how we can work together.

The Blacksburg Group, Inc., P.O. Box 242, Blacksburg, VA 24060 (703) 951-9030.

Circle 308 on inquiry card.

Circle 309 on inquiry card.

Circle 310 on inquiry card.

LETTER QUALITY

$1600

6 OUTPUT POWER SUPPLY FLOPPY, EPROM, CPU ETC.

1AND NEW NORTH: »3676. seaiei rminaiu 5W3A. 2JV/1 2A. i6W2.e: rifling); 12W0 1A. -24W03A (ooth

Orig used in NCR djuslable, w/OV proi pro!.); -I2V/01A (ad

TERMS: UPS COO- \

•r Ciaige on approval COD • S2. c

ELECTRAVALUE INDUSTRIAL

P.O BOX 157-9 f. S\

MORRIS PLAINS, NJ 07950 C""/T~

201/267-1117

ONE BOARD CP/M SYSTEM!

only $750

Assm., Tested

& Burned-In

for one week

• %Vi by 12 inches

• 10 MHZ 8085 CPU

• 64K HAM

• 3 RS-232 channels

• 8272 Floppy Disk Controller

■ Handles Single/Double Density

• One to Four Drives. 801H or 850R.

Documentation S15.

CP/M Floppy Disk Operating System S150

Check or Money Order

(

nuroconrroll

11744 Westline Industrial Drive

St. Louis. MO 63141

(314)432-1313

)

BELOW DEALERS COST!

NorthSta^

32KDD -2295.00 32K QUAD-2600.00

General Ledgei SB25 00

COD CASH IN ADVANCE-VISA/ MASTER CHARGE'

"ADD t PERCENT ON CHARGE ORDERS

CUSTOM BUSINESS COMPUTERS

103 ATLANTIC AVENUE, LYNBROOK. NEW YORK 11563-1516)867.3340

Circle 311 on inquiry card.

Circle 312 on inquiry card.

16K MEMORY — $24.00

FOR APPLE - TRS-80 - EXIDY

4116 EQUIVALENT

MITSUBISHI4116M58759-20 150ns 8for$ 28.00

NATIONALMM5290N-3 200ns 8for$ 24.00

2114-300ns

NATIONALMM2114N-3L 8for$ 26.00

IMSAI COMPATIBLE PRODUCTS

STILL A GREAT DEAL!

I 8080 ENCLOSURE KIT w/o front panel $ 95.00

(After March 31, 1981 — $115.00)

8015 JUMPSTART FP $ 32.50

8035DUALSA400FP $ 78.50

PS-28D Improved 28A @8V and 3A@ ± 16V power supply for S-100 kit ...$ 95.50

PIO 4-4 4 parallel inputs and outputs $160.00

SIO 2-2 2 serial I/O ports, good to 19,200 baud $175.00

DIO-C/D 2 board disk controller for 8" or 5V*" $350.00

CPM 2.2® For DIO including documentation $175.00

CPA Improved Imsai style front panel works with Z80, etc $225.00

VIO-X Improved video board w/8085 controller, 8275 crt controller, port mapped, on board memory, keyboard port $275.00

MDX Dual SA400 drive enclosure $ 75.00

DE 8 Dual 800R/801R horizontal style enclosure w/power supply and fan$240.00

Ask about documentation, repair service, firmware and software for your system.

component supply,me.

WW

1771 Junction Avenue San Jose, California 95112

(408)295-7171

TERMS: (1) PREPAID Send check or M.O. for merchandise amount only -we pay the shipping. (2) UPS COD or Bankcard orders by phone or mail - shipping charges added. California Residents add 6.5% Sales Tax.

Circle 314 on Inquiry card.

BYTE March 1981

Circle 315 on inquiry card.

SAVE! SAVE! SAVE!

We have discounts, free shipping and a TOLL FREE NUMBER available

Call Us! 800/531-7466

Pan American

TRS-80's

Microcomputers

Electronics

INCORPORATED

Dept. B

1117 Conway, Mission, Texas 78572

TOLL FREE ORDER NUMBER 800/531-7466

Texas & Principal Number 512/581-2765

Telex Number 767339

Radio /hack

AUTHORIZED SAMS (I NTLK

MiutaffCivd

Q)

What should you do if your local computer store doesn't have the products you want?

1) GO CRAZY or 2) GO TO HOBBYWORLD

Hobby world Electronics is the nation's leading supplier of mail order electronics. We have thousands of brand name computer products in stock.

Microsoft Z-80 Softcard *

Doubly the versatility of your Apple 11' with the power ol a Z-80 Microprocessor Fully compatible with all Apple II systems Requires 48K RAM and disk drive In eludes Microsoft BASIC 5.0 Wt. 1 lb Cat No. 269H 4>nn IT 00

Datasoft Mychess

The world champion Microcomputer chess yarne. winner of the Fifth West Coasl Computer [-"aire, can now be enjoyed by Apple II owners. Mychess is the most ad vaneed microcomputer chess yami* available Requires any Apple II, 4HK. disk. Z-80 soflcard and CP M." Wt. b 01

Special Offer: Purchase the Z-80 Softcard from this ad and we'll include Datasoft's Mychess at no extra charge! (a $34.95 value)

$295°

Cal No 2919

$34

95

* Z-80 Softcard is a registered trademark

of Microsoft. Inc. ' Apple is a registered trademark of Apple

Computer ' CP/M is a registered trademark of Digital

Research

HOW TO ORDER: Pay by check. Mastercard, Visa or C.O.D. Charge cards include expiration date and bank no. Add $1.25 add), for C.O.D, Include S2.25 for shipping and handling (J.P.S. ground. Prices valid thru month of issue. Not responsible of typographical errors.

HOBBYWORLD

ELECTRONICS ,INC.

19511 Business Center Dr. Dept. B3

Northridge, CA 91324

Call Toll Free: (800) 423-5387

Local & Outside USA: (213) 886-9200

Free Hobbyworld Catalog

Send for your FREE, 44 page Hobbyworld catalog today! If your local computer store doesn't have something you want, make the right choice . . . Come to Hobbyworld!

Name

Company Address

City.

State.

.Zip.

358 BYTE March 1981

Circle 316 on inquiry card.

VISTA

Your Supermarket

For Add-ons and

1 Peripheral Products

The Vista V80/800/8000

Family Disk Drive System

Full compatible with TRS-80,

Heath/Zenith

120 Day Warranty

40 Track Patch at NO CHARGE

V-80 Single drive system (102K) .... $ 395.00

V-60 Two drive system (204K) $ 770.00

V-600 Single drive, B52 drive (204K) . $ 595.00

V-800-2 Double dirve, B52 drives (408K) $1175.00

V-8000 Single drive, B92 drive (408K) $ 775.00

V-8000-2 Double drive B92 drives (816K) $1450.00

The Vista Model II

Totally Compatible with the TRS-80* Model II

Provides one, two or three drives

Adds up to 1.5 million bytes of on-line

storage

120 day warranty

Does everthing Radio Shack's

expansion system will do. . . for less!

Single drive (non-expandable) Single drive expansion system Two drive expansion system . Three drive expansion system Additional drives alone

$ 900.00 $1000.00 $1550.00 $2100.00 $ 525.00

Vista

V-300 Daisy Wheel Printer

Letter Quality

• Print Wheel — Industry standard 96-character Daisy Wheel (Including the extended-life dual plastic wheels)

• Printable columns (136)

• Proportional, bi-directional printing

• Interface — Industry standard parallel (RS232-C optional)

• Service - Prompt maintenance/service agreements available nationwide

• Warranty - 90 days partsand labor, one year parts only

V-300-25 $1895.00

V-300-45 $2195.00

Tractor Option $ 300.00

Vista V-100 Printer $745.00

9 x 7 dot matrix

125 cps bi-directional print speed

136 column

Industrial quality

Vista Music Machine 9

NEW! Uses latest State of the Art

LSI Technology

Requires only one slot for 9 voices!

Uses three AY3-8910's to produce 9 voices

Plays music generated by the ALF

board

APPLE IIT" compatible

ALF'" software reauired $129.95

Price:

On Drlvei

MPI BS1 40 Track, 'Double

Density 204K .... MPI B52 'Dual Head, Double

Density408K

Siemens FDD 100-5 40 Track Double

Density 204K

Siemens FDD 100-8 8" Single

Sided Drive

Shugart 801R Single Sided Drive ...

Other Products

T.16K RAM upgrade kits $ 49.95

2. NEW DOS 80 .... $149.00

3. LNW 80 (computer board) $ 86.95

4. LNW expansion board ., $ 66.95

5. H.C. Pennington books:

TRS-80 DISK AND OTHER MYSTERIES 5 18.95

E ROSOFT BASIC DECODER AND OTHER MYSTERIES $ 27.95

The Vista V-200 for Exidy

Completely packaged system, tested and ready to plug in

Includes: power supply, two 40 track drives, case, double density controllers, and all cabling and total CP/M'" documentation. Storage capacity from 400K to 1.2 meg. System software-VISTA CP/M Disk Operating System and BASIC-E Compiler recorded on 5%" diskettes Price: Starting as low as

$1199.00

S-100 version as low as $699.00

3448.00 $448.00

The Vista V-1000 Floppy Disk Drive Subsystem

Deluxe chassis with internal slide allows easy access for drive positioning and mounting.

Built to mechanically and electrically accomodate single sided drives, double sided drives — including, the most popular 8-inch Winchesterand Shugart floppy disk drives,, and 8-inch streaming tape cartridge units.

Storage capacity from 0.5 to 40 megabytes

Industrial quality cabinet with die cast

front bezel

Meets all UL and OSHA standards

Additional Savings! Front and rear retma

rail mounts provided at no extra charge

(no external slides)

Desk or rack mountable

Features modular construction with

removable sub-assembly that allows easy

cabinet positioning and mounting

Drives pull out for easy service and

maintenance

Cabinet $ 395.00

Cabinet with (2) single sided drives $1595.00 (Includes power supply and cable) Cabinet with (2) double sided drives $2295.00 (Includes power supply and cable)

232

The Vista Computer Company

1317 E. Edinger Avenue, Santa Ana, California 92705,(714)953-05231

CALL TOLL-FREE 800-854-8017

'TRS-80 is a registered trademark ofRadio Shack, a Tandy Corporation ™ Apple is a registered trademark of Apple Computer Co. '" CP/M is a registered trademark ofDisital Research

Circle 317 on Inquiry card.

BYTE March 1981

359

apple II plu/

With 48Kof memory!

51199

With thepurchase of the APPLE III, select Iromthe below SPECIAL PRICING: /

'Base2 printer..^599' OisklMcont....S85t

Diskll 475"<

Ser.PrinterCd. . /79~'

SupRMod 23"

3wayl/0Selecl.. 33* Video 100 EL. 119" FirmwareCard. 179" JHFtoRCACable.5"

74LS00 .26 74LS155 US

74LS02 .26 74LS158 .75

74LS03 .26 74LS160 .95

74LS04 .26 74LS161

74LS08 .28 74LS162 95

74LS09 .26 74LS163 1.60

74LS10 .26 74LS164 .65

74L'S20 .26 74LS165 .65

74LS21 .28 74LS170 175

74LS22 .26 74LS174 75

74LS26 .49 74LS175 .75

74LS27 .26 74LS190 .75

74LS30 .28 74LS193 95

74LS32 .32 74LS195 95

74LS38 .32 74LS196 85

74LS42 .65 74LS221 1.40

74LS4B .78 74LS240 165

74LS51 .25 74LS241 1.65

74LS54 .35 74LS243 145

74LS74 .38 74LS244 145

74LS75 60 74LS245 2 25

74LS83 44 74LS253 95

74LS85 .95 74LS257 95

74LS86 .95 74LS258 95

74LS90 .69 74LS259 2 85

74LS93 .69 74LS279 .44

74LS107 .45 74LS283 100

74LS112 .38 74LS293 185

74LS113 .48 74LS298 1.20

74LS122 .48 74LS366 95

74LS123 .95 74LS367 .55

74LS126 .69 74LS368 55

74LS138 69 74LS373 1.39

74LS151 .44 74LS374 1.39

kll/oppkllpki,

With 64Kof memory!

51389

nppic imtRPACE cbrdj

cEimtonKi nmnii t tit

communKnnoni ■"*<>**. a uw* m

DUHIICOrtTTKMLIft d.o./.JJ H«

WTHn BAIK nWMBMH m

tvnuorr nmwMH m

MWCAl mnCUOCJ MCHMf 4«4

mmhw pmtnn m

WWTOTVFfOq/HOMV M

i/idec 100

APPLE EXPANSION KIT | 16K Memory Add-On

nHTAtCW ADO-ON Kir INCLUDES IHSTRUCTIOHS

*39°

'125

12'

Ldsdex Corp

COLOR

^Oy/MON|TO|13

EPROMS 270B Ik x 0 5.95 8 FOR 40.00 2716 2k x 8 9.95 single ps. 8 FOR 80.00 2732 4k x 8 24.95 2716 2k x 8 6.95 triple p.s.

^pk deck/cakndaf *12495

On board batteries with one year lite.

UsesMSM5832<xysa/coHroMed

California Computer Systems

MISCELLANEOUS

803 ec

NE555V

7905 .

7908 '

7915

7918

7805

7806

7808 .

7812-'

MC1330AIP

MC1350P

MC1358P

LM380N

NE565N

MC1458P

IS410 SCR

IT410 TRIAC

2.65 .27

1.60 1.15 1.50 1.75 1.25 .50 .95 .95

LOGIC NOIE

KIT

BUY FIVE OR MORc

S16.9S each

CARRY

Titer

COnCORD

COfflPUTCR

componenn

HEATHKfT*

COMPUTER OWNERS

H47 COMPATABLE DISK OPERATING SYSTEM 8"DuatSided,Doubfe Density Intelligent MASTER /SLAVE

BY REMEX

$2450°°

SWITCHES

2114 200ns 3.50

2114L 300ns 3.75

2114L 200ns 4.25

4116 300ns 4.95

1971 SOUTH STATE COLLEGE

ANAHEIM, CALIF. 92806

CHECK OR M 0. NO COD. CAL.RES.AD0 6/

(714)9370637

A0D»1 50 FORFHT.ON ORDERS UNDER *50. 5°/o IF OVER »50.

SN7400N SN7402N SN7404N SN7408N SN7410N SN7412N SN7413N SN7414N SN7416N SN7417N SN7423N SN7425N SN7430N SN743/N SN7438N

20 SN7440N .22 SN7442N .22 SN7443N .24 SN7445N .22 SN7451N

28 SN7454N .35 SN7474N .49 SN7475N .29 SN7482N

29 SN7492N .28 SN7493N

25 SN7495N .23 SN7496N 29 SN74122N 24 SN74136N

MSM5832 $ "7 c

MICROPROCESSOR iHO REAL-TIME CLOCK

The MSM533? is .. monolnn.r maul-gale CMOS ■meg'

ntje addressable 4-tji hours BAY-QF-WEEK

is conirolleO by « tn

22 SN74141N 57 SN74151N 78 SN74153N .78 SN74154N 20 SN74155N 20 SN74157N .32 SN74160N 32 SN74161N 1.05 SN74163N .50 SN74164N .48 SN74165N .60 SN74174N .70 SN74175N .39 SN74180N .95 SN74181N

.651 .651 1251 80l .691 .951 .651 .85 1 .87 I .871 .951

69 I .75 I

1.15l

TRS80 ,

16K MemofyAddfln J

'4395

KIT CONTAINS I DIP SWITCHES! AND DETAILED! INSTRUCTIONS!

SOROC

IQ12tr^6S9

O 0 o

© ® w

No"Glitches'\ Surges Or Interference

IMC MPDTI7 TURNS AN OflONARY OUTLET INTO A CONTROL LED FILTERED POWER SOURCE TOR UP

TOElGHTOeVrCES

S8P°

Dual Trace Oscilloscope

HITACHI 30 MHz

• TV sync-separater circuit

• High-sensitivity 1 mV/div (5MHz)

9 Sweep-time magnifier (10 times)

• Z-axis input (Intensity modulation)

• Signal delay line

• X-Y operation

• Trace Rotation

Model V302B

$995

More sensitive to your input

EPROMS

2708 2716

$4?o

$790

2114L

5375

4116

(200ns) $375

ANCRONA SPECIAL

64K Dynamic RAM

HM4864 $97.00

€

California Computer Systems

32K STATIC HAM MODULE

[ASSEMBLED AND TESTED)

2032A 450ns RAM $710.00

2032B 300ns RAM 79S.O0

2032C 200ns RAM 830.00

B4K DYNAMIC RAM MODULE

(ASSEMBLED AND TESTED) 2065C 200ns RAM. . . . S700.00 16K STATIC RAM MODULE

(ASSEMBLED AND TESTED)

211GA 450ns RAM S349.95

211GB 300ns RAM 389.35

211BC 200ns RAM. . . . 399.95

MAINFRAME 220DA Assy and Tesled S399.95 2200K Complete Kil 349.35

Note: Spec. color-Black, Blue.

Brawn, Office Cream, or Grey. FLOPPY DISK CONTROLLER 2422A Assy£1 Tesled . $400.00 4-Port Serial I/O Interface 2710A Assy&Tesied. . S340.00 Serial/Parallel I/O Interface 2718A Assy6 Tesled. $360.00 4-Port Parelle! I/O Interface 2720A Assy&Tesied. . . $250.

Z-BO" CPU 2810A Assy&Tesied. . S300.00

PROGRAMMABLE TIMER

7440A Assembled and Tested $114.95

PARELLEL INTERFACE

7720A Assy 6 test cable 6 std firmware. $119.95

7720 B Assembled and tested, cable & Centronics- type

firmware included S119.95

STORES 00 NOT ACCEPT MAIL ORDERS

MAILORDER

P.O. BOX 2208Y CULVER CITY. CA90230

PHONE ORDERS (213) 641-4064

Gidei pricing \

ARITHMETIC PROCESSOR

7811B Assembled and tested: CCsoft diskette included (Compatible with Apple II" computers with a disk drive.) $399.95

7SI1C Assembled and tested, CCsoft ROM included (Compatible with Apple II PLUS" compu lers and Apple II" computers with an Applesoft" card) $399.95

Assy & Tesled Less ball.

ASYNCHRONUS

SERIAL

INTERFACE

Assy & tested: cable included . . $159.95

CALENDER/ CLOCK MODULE

SYNCHRONUS

SERIAL

INTERFACE

Assy & tested, cable included . - $179.95

GPIB (IEEE-4BB)

INTERFACE

Assy & tested; cable included . . $300.90

CENTRONICS" PRINTER INTERFACE

7728A Assy Er tested, cable not included. . . $119,95

Quite Portable Very Affordable and Unbelievable

Versatile! the PET computer may

very well be a lifetime investment

• Large Keyboard

• Separate Numeric Pad

• Graphics on Keys

$995

* I 6% *

DISCOUNT COUPON

Bring this 4'01Tl*OINT intooneofourstoresor mail to our Mail Order address shown below

and receive a IO%»IS<OI\T on purchases from this Ad of S1 00.00 or more. Offer I \ l> llll N on Miiri-h ;t I. I !rU I

NAME ...

ADDRESS

CITY STATE

ZIP PHONE NO

Coupons accepted only with full name and address filled m.

VISIT A STORE NEAR YOU TODAY - We stock a large selection of Technical Books, Discrete Components, Integrated Circuits, Test Equipment and Electronic Supplie

ATLANTA

3330 Piedmont Rd. N.E.

Atlanta. GA 30305

(404) 261-7100

CULVER CITY

11080 Jefferson Blvd.

Culver City. CA 90230

|213| 390-3595

HOUSTON

2649 Richmond

Houston. TX 77098

(713) 529-3489

PORTLAND

1125 N.E. 82nd Ave.

Portland. OR 97220

(503) 254-5541

SANTA ANA

1300 E. Edinger Ave

Santa Ana. CA 92705

(714) 547-B424

SUNNYVALE

1054 E. El Camino Real

Sunnyvale. CA 94087

(408) 243-4121

TUCSON

451 8 E. Broadway

Tucson. AZ 8571 1

(602) 881-2348

360

BYTE March 1981

Circle 319 on inquiry card.

THE STAR MODEM

From Livermore Data Systems

RS232 MODEM IEEE 488 MODEM RS232 CCITT IEEE 488 CCITT

SALE $135

SALE $245

$170

$280

STAR Modem is the price performance leader with a full 2 YEAR FACTORY WARRANTY.

WE CARRY THE BLACK APPLE

I BelleHdluell

MAOl ( Xl'UJSIVt LV rOH OF LI >. HOWF LI BY

' qpplc computer inc.

EBS Business System for PET/CBM

Extremely comprehensive package for small business. Fully integrated inventory and accounts receivable system including invoices, packing slips, mail labels, statements, bank deposit slips, and 17 reports. Allows any of 10 standard letters to be merged with customer record info on either a selective or complete file basis. Demo disk and system description available for $3.00.

Piper-Mate Word Processor $29.95

PET/CBM full featured 60 command system by Michael Riley. Uses either tape or disk and any printer. Includes in-text commands, floating cursor, scrolling, etc.

6502

7.45 10/6.95 50/6.55 100/6.15

6502A

8.40

10/7.95 50/7.35 100/6.90

6520 PIA

5.15

10/4.90 50/4.45 100/4.15

6522 VIA

6.45

10/6.10 50/5.75 100/5.45

6532

7.90

10/7.40 50/7.00 100/6.60

2114-L450

3.45 20/3.35 100/3.25

2114-L200

4.15 20/3.95 100/3.75

2716 EPROM (5 volt)

9.90 5/9.45 10/8.90

TMS 2532 EPROfv

23.50

4116-200 lit RAM

8 for 30.00

S-100 Wire Wrap

2.65

KM MM Pascal for PET $75

Subset of standard Pascal with true machine language translator for faster execution. 16 K with tape or disk.

EARL for PET (disk file based) $65

Editor, Assembler, Relocater, Linker to generate relocatable object code.

fuMFORTH-r- for PET/CBM $65

A full-featured FORTH with extensions conforming to Forth Interest Group standards. Includes assembler, string processing capabilities, disk virtual memory multiple dimensioned arrays, floating point and integer processing.

MIPL0T Intelligent Plotter by Watanabe Instruments (Digiplot)

SPECIAL $1145

Has all intelligent functions for producing graphs and drawings including 8 vector and 4 character commands. Solid and broken lines can be specified. Character generator for alpha, numeric, and symbols. Characters can be rotated in 4 orientations, and can be 16 sizes. Coordinate axes drawn by specifying graduation inteival and number of repetitions. Parallel ASCII interface, 11x17 paper.

FLEX-FILE Data Base for CBM/PET $60

Random file handling system with Report Writer and Mail Label Handler. By Michael Riley

DISKS

(write for quantity prices)

SCOTCH (3M) 514" SCOTCH (3M) 8" Maxell 5%" Maxell 8" Disks Verbatim 5V*"

(add 1.00 for Verbatim Verbatim 8" Dbl. Dens. BASF 5%" BASF 8"

Diskette Storage Pages Disk Library Cases

10/2.90 50/2.80 100/2.70 10/2.95 50/2.85 100/2.75 10/4.25 50/4.10 100/3.95 10/4.65 50/4.50 100/4.35 10/2.45 50/2.40 100/2.35 5'A" plastic storage box) 10/3.45 50/3.35 100/3.25 10/2.60 20/2.50 100/2.40 10/2.65 20/2.55 100/2.45 10 for 3.95 8" - 2.85 5%" - 2.15

commodore

CBM-PET SPECIALS

,<<, Up to $235 FREE /^ mirehindlsi with purchase of ^ one of following CBM-PET Itemtl

CASSETTES - AGFA PE-611 PREMIUM

High output, low noise, 5 screw housing, labels. C-10 10/5.65 50/25.00 100/48.00

C-30 10/7.30 50/34.00 100/66.00

All other lengths available. Write for price list.

•

FREE $1795 235 1795 235 795 75 995 150 1295 205 1295 205 795 100 95 12 395 50

4 PART HARMONY MUSIC SYSTEM for PET

Allows you to easily enter, display, edit and play 4 part harmony music. Includes whole notes thru 64ths (with dotted and triplets), tempo change, key signature, transpose, etc. The KL-4M unit includes D toA converter and amplifier (add your own speaker). KL-4M Mmk Burt with VMM Pufrmi $59.90

8032 32K - 80 column CRT

8050 Dual Disk Drive- 1 megabyte

8N Full size graphics keyboard

16K Business or Graphic Keyboard

32K Business or Graphic Keyboard

2040 Dual Disk Drive- 343,000 bytes

2022 Tractor Feed Printer

C2N External Cassette Deck

CBM Voice Synthesizer

WRITE FOR SYSTEM PRICES

♦"EDUCATIONAL DISCOUNTS***

Buy 2 PET/CBM Cimittin, rtcilii 1 FREE

WordPro 3 - 32K CBM, disk, printer WO

WordPro 4 - 8032, disk, printer 255

OZZ Data Base System for CBM 8032 335

VISICALC for PET, ATARI 170

BPI General Ledger, AVP, A/R for PET/CBM 270

Programmers Toolkit - PET ROM Utilities 34.90

2 Meter IEEE to IEEE Cable 43.00

PET Spacemaker Switch 24.90

Dust Cover for PET 6.90

IEEE-Parallel Printer Interface for PET 105

IEEE-RS232 Printer Interface for PET 149

The PET Revealed 17.00

Library of PET Subroutines 17.00

Source Hookup 88

Over 1000 programs and services available.

EPSON MX-80 Printer

$545

STARWRITER Daisy Wheel Printer

$1500

Centronics 737 Printer

$790

NEC Spinwriter - parallel

$2500

XYMEC Hl-Q 1000 Intelligent Daisy Wheel

$2150

Leedex Video 100 12" Monitor

$129

ZENITH DATA SYSTEMS

Zenith Z19 Terminal (factory asm.)

$735

Zenith Z89 with 48K

$2150

SYM-1

$209

SYM BAS-1 BASIC or RAE-1/2 Assembler

$ 85

KTM-2/80 Synertek Video Board

$349

KIM-1 (add $34 for power supply)

$159

Seawell Motherboard - 4K RAM

$195

Seawell 16K Static RAM - KIM, SYM, AIM

$320

A

ATARI 800 $777

All Atari Modules 20% OFF

115 E. Stump Road Montgomeryville, PA 18936

215-699-5826

A B Computers

ATARI EDUCATIONAL PLAN writ, lor d.t.n.

A P Products 15% OFF APHobby-Blox 15% OFF

ALL BOOK and SOFTWARE PRICES DISCOUNTED

The 8086 Book (Osborne) $12.75

Z8000 Assembly Language Programming $10.60

PET Personal Computer Guide (Osborne) $12.75

PET and the IEEE 488 Bus (Osborne) $12.75

6502 Assembly Language (Osborne) $ 9.90

Programming the 6502 (Zaks) $10.45

6502 Applications Book (Zaks) $10.45

6502 Software Cookbook (Scelbi) $ 9.45

CP/M Handbook (w/ M P/M) Zaks $ 11.85

WRITE FOR CATALOG.

Add S1 25 per order for shipping We pay balance of UPS surface charges on all prepaid orders Prices listed are on cash discount basis Regular prices slightly higher

Circle 320 on inquiry card.

BYTE March 1981

361

Circle 321 on inquiry card.

HICKOK DIGITAL MULTIMETERS

MX-333

Model LX303

$6950

V1IZ Tech DMM 3VzDigit LCD Readout

Model WD 747 $"7Q95

Beckman DIGITAL MULTIMETERS

Model TECH 300 1 09 Model TECH 310 140

Model TECH 330

*19995

DIGITAL MULTIMETERS

Model 462 Model 463 £$£2

M9995M6995S» '

Complete with nickelcadmium batteries, AC charger/adapter, test leads

<5ES)

Magnifier Lamp

Precision ground and polished ■ magnification lens

Model LFM-1A *65.

Casio CalculatorCalendar Watclu

Model C-80

$4250

SMB 15 MHz Miniscope

■ Rise time 11.7 nS or less ■ Built-in signal delay line ■ Flat

«1

1. <a

h a Ljjja _ 11

Model 1420

Dual Trace fiu]S„ran9'n9 5 "30 MHz (Triggered Scope

Model 1479A

Digital

Pulsar Probe Model dp-ioo

50 MHz

Pulsar Probe moiici dp so

3V2-Digit 0.1% Digital ~A Capacitance Meter

j Model 3001 *2337^

Function Generator

Model 2001 $-j 5795

Proto Boards

ModeH PB-104 '

Fully assembled

*5995

Logic Monitor

• Automatically

displays static and

dynamic logic •

Workswith DTL, Model LM-1

HTL, TTL. and

CMOS

*5995

.Touch Test 20 Multimeter

~^| A portable/

I bench-type I meter

15 MHz Dual Trace Triggered

SMSigJfA Miniscope

B»^6$[M»J?// Model MS-215

30 MHz Dual Trace Triggered Miniscope Model Ms-230

PK40D

4 Pc Standard Starter Kit • One (1) Slandard Command ConsolE ■ Two |2| Lamp Modules ■ Ore (I) Appliance Module'

PK500 5 Pc Ultrasonic Starter Kit "One (1) Oeluie J, Ultrasonic Command Console ■ One (I) Hand Held Remote *' Unit ■ Two (2) Lamp Modules ■ One (1] Appliance Uml

LM50I Lamp Module $13-95

AM601Applianct Module $13.95 WS7C1 V/ail Switch Modulasi3.9S WS711 Wall Switch Module

withindepencJenl On-Otl power bjllons S15.95

74"

todule

9995

The Timer $5995

Miniature High Fidelity 3-Way Stereo Speakers

*5995

BB1

Model TC201

FIDELITY

Chess Challenger 7 $7995

Model BBC

Sensory Chess Challenger$110.

Voice Sensory

Challenger

$24995

WAHL*

Cordless Soldering Iron $2995

Th&iunaE-Spat

Circuit Tester

Finds faulty components \ quickly and easily

*2995 Model 5800

MURAPHONE Cordless Telephone System

Model $11 fl 300 I • V.

Welter"

WTCPN Controlled Output Soldering Station

Model WTCPN

$5750

Service Master Tool Kit

Soldering Station

VimSupeTGase

Model 70260

$4g95

24995

In-Dash Car Stereos

8-Track AM/FM $CO50,

Model JCS 420 yJ£m |

Cassette AM/FM $575<T

ModelJCS505 *"

Digital Cassette AM/FM $8995

With ClOCk Model JCS 607

Graphic Equalizer

Model GE 5000 $3Q9S

6x9 3-Way $1295 ea.

Speakers ■ 20 oz. magnet Model BP2000-69 TRD

855 Conklin Si. Farmingdale, N.Y. 11735

■ VISA ■ COD

■ Money Order

■ Check

N.Y. Stale residem appropriate sales lax

ADO FOB SHIPPING AND INSURANCE

to! 250.00 S 150

S2M.0CU MO 00 5.00

SOI. nolo 750.00 7 50

751.0010 1000.00 10.00

mil 10DO.00 12.50

COO't Kill

^(800)645-9518

in N.Y. Stale call (516) 752-0050 I

Add-On

Disk Drive

Subsystems

FOr Apple, TRS-80, S-100 Based Computers

Expansion and enhanced capabilities are key words in achieving full utilization of your computer system. Our complete line of LOBO disk drive subsystems are the ideal, cost-effective way to provide the expansion capabilities you need to meet your system growth requirements. All of our subsystems are complete, thoroughly-tested, 100% burned-in, and leature a 1 year 100% parts/labor warranty.

APPLE

3101 Minifloppy, 31011 Minifloppy w/interface card

B101CA One SA800 in cabinet w/power, ODC* Controller, cable and manual B202CA Two SA800 in cabinet w/power, DDC* Controller, cable and manual 5101CA One SAB50 in cabinet w/power, DDC* Controller, cable and manual 5202CA Two SAB50 in cabinet w/power, DDC* Controller, cable and manual 'Double Density Controller

S-100 BASED COMPUTERS

MODEL NO. DESCRIPTION

4101C SA400 in cabinet w/power

6212C Two SA801 in cabinet w/power

5212C Two SAB51 in cabinet w/power

GENERAL

MODEL NO

B212

B212C

5212

5212C

DESCRIPTION

Two SA801 in cabinet

Two SA801 in cabinet w/power

Two SA851 in cabinet

Two SA851 in cabinet w/power

TRS80

MODEL NO DESCRIPTION

4101C SA400 in cabinet w/power

B101C II One SA800 in cabinet w/power lor Mod. I

B202C II Two SA800 in cabinet w/power tor Mod.

C802 Cable for Mod. II

CB05 Cable for TRS80 Minifloppy

MODEL NO

DESCRIPTION

C808

Cable for TRS80 Eight inch Floppy

LX80

Double density expansion interface

RS232

Dual Serial Port Option

16K

16K Byte RAM for LX80 (32KB max

VTOS

4.0 Disk Operating System

INVENTORY CO.,

P.O. Box 185, Santa Yhez,Ca., 93460 (805) 688-8781

362 BYTE March 1981

Circle 322 on inquiry card.

WE WILL NOT BE UNDERSOLD

DISK DRIVES

$314 PRINTERS

40 track, 102K Bytes. Includes power supply and TRS-80* compatible silver enclosure. Ready to plug-in and run the moment you receive it. Can be intermixed with each other and Radio Shack drive on same cable. 90 day warranty. One year on power supply. Available for 220 Vac (50 Hz) operation. External card edge included.

FOR TRS-80*

CCI-100TEAC

CCM00MPI

CCI-280

For Zenith Z89

CCI-189 Z-87

5% ", 40 Track (102K Bytes) for Model I 5'/.", 40Track (102K Bytes) for Model I 5V«", 80 Track (204K Bytes) for Model I

5 V«", 40 Track (102K Bytes) add-on drive Dual 5 Va" add-on drive system

|gk7gaiiIiMtMtM:liM

MAINFRAME, Z-80 CPU, CONTROLLER, RAM, and 2P + 2S CARDS

8" SHUGART SA801R DISK DRIVES

$314

$319 $429

$394 $995

$CALL

$425

DISK OPERATING SYSTEMS

PATCHPAK#4by Percom Data

CP/M® for Model I, Zenith $145 NEWDOS Plus 40track $79

$ 8.95

for Model II, Altos $169 NEWDOS 80 $135

DISKETTES — Box of 10 with plastic library case 5'/i" Scotch $35 Maxell $40 BASF/Verbatim $24

8" Scotch $50 Maxell $55 BASF/Verbatim $36

CLEAR PLASTIC CASE-Holds 50 5% "diskettes $19

$CALL APPLE III-96K $3749

COMPLETE SYSTEMS

ALTOS ACS8000 Computers APPLE II-16K $1075

Call for other Apple products

TRS-80* Model II-64K $3499 • Model III-16K $899 Used TRS-80* Model I Computers, tested and guaranteed $CALL

ZENITH Z89,48K all-in-one computer $2395

ZENITH Z19 $735

TELEVIDEO 920C $748

ATARI 400 $479 ATARI 800 $769

APF Game Only $95 Complete System $489

MATTEL INTELLIVISION $229

$129 $379 $155 $226 $238 $416 $120

MONITORS

LEEDEX

12'

B&W Video 100

ZENITH

13'

Color

SANYO

9'

B&WVM4509

SANYO

12'

B&W DM5012

SANYO

12'

Green Screen DM5112

SANYO

13'

Color DMC6013

APF

9'

B&WTVM-10

TELECOMMUNICATIONS

LIVERMORE STAR MODEM 2-year guarantee UNIVERSAL DATA SYSTEMS UDS-103 D-CAT HARD WIRED DIRECT MODEM AUTO-CAT Auto Answer, Direct Connect Modem

$145 $179 $189 $229

R.O. with Tractor Feed

NEC Spin writer

Letter Quality High Speed Printer

Includes TRS-80* interface software, quick change print fonts, 55 cps, bidirectional, high resolution plotting, graphing, proportional spacing: R.O. $2395 $2595 KSR with Tractor Feed $2895

C.ITOH Starwriter, 25 CPS, daisy wheel printer $1795

C.ITOH Starwriter II, 45 CPS, daisy wheel printer $1995 Letter quality printers. Use up to 15" paper. 1 year warranty on parts. 3 months on labor. Proportional spacing and bidirectional printing. Same as VISTA V300.

EPSON MX-80 $CALL

PAPER TIGER IDS445 Graphics and 2K buffer $699

IDS 460 Bidirectional, 160 cps, graphics and 2K buffer $1050

IDS 560 132 Columns, graphics $1599

ANADEX DP-9500/01 $1345 DP-8000 $849

OKIDATA Microline 80 Friction and pin feed $499

Tractor Feed, friction, and pin feed $625

Microline 82 Bidirectional, friction and pin feed $719

Microline 83 Bidirectional, 120 cps, uses up to 15" paper $995

CENTRONICS

737 Friction & pin feed $780

730 Friction & pin feed $595

779Tractorfeed $969

EATON LRC7000+ 64 columns, plain paper $269

TI-810 Includes TRS-80* software and

Compressed print, vertical form control $1865

16K RAM KITS 2 for $56 $30

200 ns for TRS-80*, Apple II, (specify): Jumpers $2.50

ACCESSORIES

Z-80 SOFTCARD: Your key to software expansion. The plugin Z-80 Softcard transforms your Apple into a Z-80 while keeping all the benefits of the 6502. Comes with CP/M in two disk format, MBASIC and GBASIC, full documentation and utility programs. $339.00

SCOTCH HEAD CLEANING DISKETTE: Cleans drive Read/Write head in 30 seconds; specify5Va "or8". $25.00

FLOPPY SAVER: Protection for center holes of 5Vi" floppy disks. Installation tools and rings for 25 diskettes. $ 11.95

Re-orders of rings only $ 6.95 VIDEX BOARD 80 Column, U/L case conversion card $279.00 CRT FILM: Helps eliminate external glare, 9" RF MODULATOR: Adapts video to TV TRS-80 & OTHER MYSTERIES

NEC SPINWRITER THIMBLE $11.95 RIBBON

CCS CARDS: Parallel or serial printer interface cards RS232: For Radio Shack Interface. DISK-DRIVE EXTENDER CABLES: Fits all mini-disk drives. SIX (6) PRONG ISOLATOR: ISO-2 AC FILTER/6 PRONG POWER STRIP DISK DRIVE CABLES: 2 drive $29.00 4 drive

DUST COVERS: TRS-80/Apple PLASTIC DISKETTE HOLDER: For ring binder, holds 20

COMMUNICATIONS SOFTWARE

CCI-TELNET COMMUNICATIONS PACKAGE:

Communications with mainframes and micros. CP/M

compatible $149.00

$ 29.00 $ 29.00 $ 18.95 $ 6.00 $115.00 $ 84.00 16.95 54.00 39.00 35.00 7.95 8.00

For fast delivery, send certified checks, money orders or call to arrange direct bank wire transfers. Personal or company checks require two to three weeks to clear. All prices are mail order only and are subject to change without notice.

dealer (national/international) inquiries invited Send for FREE Catalogue

TO ORDER CALL TOLL FREE 1-800-343-6522

TWX: 710-348-1796 Massachusetts Residents call 617/242-3361

The CPU SHOP

5 Dexter Row, Dept. B03M

Charlestown, Massachusetts 02129

Hours 10AM-6PM (EST) Mon.-Fri. (Sat. till 5)

Technical Information call 617/242-3361 Massachusetts Residents add 5% Sales Tax Tandy Corporation Trademark/^'Digital Research

l#Ws

VISA'

\&iWC,

Circle 323 on inquiry card.

BYTE March 1981 363

Circle 324 on inquiry card.

ii

CALIFORNIA COMPUTER SYSTEMS

32K RAM BOARD A&T.

450 NSEC . . $579.95, 200 NSEC

$62995

16K RAM A&T.

450 NSEC $255.95. 200 NSEC

S285.95

64K DYNAMIC A&T

200 NSEC . .

S579.95

Z80 PROCESSOR A&T.

S259.00

DISC CONTROLLER

S339.95

APPLE IEEE INSTRUMENTATION INTERFACE

KIT 7490. A&T

S275 00

ARITHMETIC PROCESSOR FOR APPLE 7811A. A&T $342.80

APPLE ASYNCHRONOUS SERIAL INTERFACE 7710A. A&T $137.10

APPLE SYNCHRONOUS SERIAL INTERFACE

7712A. A&T $153.95

ALL OTHER CCS PRODUCTS AVAILABLE

SStTJ

PB-1 2708 & 2716 Programming Board with provisions for 4K or 8K EPROM. No external supplies required. Textool sockets. Kit S 143.00

CB-1A 8080 Processor Board. 2K of PROM 256 BYTE RAM power on/rest Vector Jump Parallel port with status. Kit S146.00 PCBD . ...S31.95

VB-3 80x24 VIDEO BOARD. Graphics included. 4MHZ. Kit $379.95

IO-4 Two serial I/O ports with full handshaking 20/60 ma current loop: Two parallel I/O ports. Kit ...$168.00 PCBD S31.95

VB-IC 64x16 video board, upper lower case Greek composite and parallel video with software. S-100.

Kit S 1-43.00

CB-2 Z80 CPU BOARD. Kit $199.95

AIO APPLE SERIAL/PARALLEL Kit S144.95

ALL OTHER SSM PRODUCTS AVAILABLE

W777C,

inc. WAMECO INC.

MEM-3 32K STATIC RAM 2114 24 bit

addressing $36.95

FDC-1 FLOPPY CONTROLLER BOARD will drive shugart, pertek, remic 5" & 8" drives up to 8 drives, on board PROM with power boot up, will operate

with CPM'" (not included). PCBD $43 95

FPB-1 Front Panel. IMSAI size, hex displays. Bytrj, or instruction single step. PCBD $48 50

QM-12 MOTHER BOARD. 13 slot, terminated, S-100 board only $39 95

CPU-1 B080.A Processor board S-100 with 8 level vector interrupt. PCBD $28 95

RTC-1 Realtime clock board. Two independent interrupts Software programmable. PCBD $25 95

EPM-2 2708/2716 16K-32K EPROM CARD. PCBD $2895

QM-9 MOTHER BOARD. Short Version of QM-12. 9 Slots. PCBD $33 95

MEM-2 16Kx8 Fully Buffered 2114 Board. PCBD $2895

PTB-1 POWER SUPPLY AND TERMINATOR BOARD.

PCBD $28 95

IOB-1 SERIAL AND PARALLEL INTERFACE. 2 parallel, one serial and cassette.

PCBD $28.95

2708 .... $7.50 2114L 450 NSEC $4.99

2716 ..$25.95 2114L 200 NSEC ... $5.99

M

(415) 728-9121 P.O. Box 955 • El Granada, CA 94018

Please send for IC, Xistor and Computer parts list

MARCH SPECIAL SALE ON PREPAID ORDERS

[Charge cards not included on this offer) A & T 8K X 8 RAM BOARD SALE

ON SSM, MB-6B, PCBD $74.95

ON WAMECO MEM-1, PCBD $74.95

450 NSECONDS ASSEMBLED AND TESTED. PART MAY BE REMARKS. 2.5 AMPS TYPICAL. WAMECO PCBD

IOB-1. CPU-1 $24.95 EA.

PTB-1, RTC-1 $22.95 EA.

MIKOS PARTS ASSORTMENT WITH WAMECO AND CYBERCOM PCBDS

MEM-3 less RAM $ 95.95

With 2114L-4 .5350.00

With 2114 L-2 S390.00

CPU-1 with MIKOS =2 8080A CPU $99.95

QM-12 with MIKOS 'A 13 slot mother

board $1 10.95

RTC-1 with MIKOS =5 real time clock $65.95

EPM-2 with MIKOS »11 16-32K EPROMS

less EPROMS $65 95

QM-9 wilh MIKOS M29 slot mother

board $99.95

FPB-1 with MIKOS »14 all parts

for front panel $144.95

MIKOS PARTS ASSORTMENTS ARE ALL FACTORY MARKED PARTS. KITS INCLUDE ALL PARTS LISTED AS REQUIRED FOR THE COMPLETE KIT LESS PARTS LISTED. ALL SOCKETS INCLUDED

LARGE SELECTION OF LS TTL AVAILABLE

PURCHASE S50.00 WORTH OF LS TTL AND GET 10°oCR EDIT TOWARD ADDITIONAL PURCHASES. PREPAID ORDERS ONLY.

VISA or MASTERCHARGE. Send account number, interbank number, expiration date and sign your order. Approx. postage will be added. Chech or money order will be sent post paid in U.S. [I you are not a regular customer, please use charge, cashier's check or postal money order. Otherwise there will be a twoweek delay for checks to clear. Calif, residents add 6% tax. Money back 30-day guarantee. We cannot accept returned IC's that have been soldered to. Prices subject to change without notice. SID minimum order. $1.50 service charge on orders less than 550.00.

BUILD YOUR OWN LOW COST MICRO-COMPUTER

POWER SUPPLIES

FOR S-100 BUS, FLOPPY DISKS, ETC.

POWER TRANSFORMERS (with mounting brackets)

ITEM

USED IN

PRI. WINDING

NO.

KIT NO.

TAPS

Ti

1

0V, 110V, 120V

T2

2

0V,110V, 120V

T3

3

0V, 110V,120V

Tn

4

0V, 110V, 120V

T5

—

0V,110V, 120V

SECONDARY WINDING OUTPUTS 2x8 Vac 2x14 Vac 2x24 Vac

SIZE WxDxH

UNIT PRICE

2X7.5A 2X12.5A 2X9A 2x4A 2x3A

2X2.5A 2X3.5A 2X2.5A (28V, CT) 2x2A

2X2.5A 48V, CT, @3A

POWER SUPPLY KITS (open frame with base plate, 3 hrs. assy, time)

ITEM USED FOR @ +8 Vdc ® - 9 Vdc @ + 16 Vdc @-16 Vdc @ +28 Vdc

3V«"x3%"x3'/," 3y<"x43/i"x3y,"

33/4"x3%"x3'/„" 3"x3"X2V2"

SIZE W X D X J

21.95 27.95 29.95 22.95 14.95

UNIT PRICE

KIT 1 15 CARDS SOURCE 15A

KIT 2 SYSTEM SOURCE 25A

KIT 3 DISK SYSTEM 15A

1A

2.5A 3A 2A

2.5A 3A 2A

4A

12"x5"x47/," 12"x5"x47," 14"x6"x4'/,"

52.95 59.95 67.95

DISK SYSTEM PWR SUPPLY S3 assy. & tested, open frame, size io"(W)x6"(D)x4%"(H) 92.95

UNREGULATED OUTPUTS: +8V@15A, ±16V@3A.

REGULATED OUTPUTS: +5V@3A, -5V@1A, + 24V@4A, SHORTS PROTECT. IDEAL FOR THE SYSTEM WITH 12 SLOTS MAINFRAME & TWO 8" DISK

DRIVES, SUCH AS SHUGART 801R OR SIEMANS FDD 100-8. (OPTION: OVPfor + 5V @ ADD $5.00)

DISK DRIVE POWER SUPPLY "R3" assy. & tested, open frame, size:9"(W)x6%"(D)x4>/,"(H) 67.95

SPECS: +5V @ 5A REGUL, OVP, - 5V @ 1A REG., + 24 @ 5A REG., SHORTS PROTECT. OPTIONS: 1. REPLACE + 24V BY + 12V

2. ADD ± 12V @ 1A, $12.00 MORE. IDEAL FOR 2 SHUGART 801/851 OR SIEMANS FDD 100-8/200-8 DISK DRIVES & ROCKWELL AIM-65. SHIPPING FOR EACH TRANSFORMER: $4.75. FOR EACH POWER SUPPLY: $5.00 IN CALIF. $7.00 IN OTHER STATES. CALIF. RESIDENTS ADD 6% SALES TAX. OEM WELCOME.

MAILING ADDRESS: P.O. BOX 4296 TORRANCE, CA 90510

SUNNY INTERNATIONAL

(TRANSFORMERS MANUFACTURER) (213) 328-2425 MON-SAT 9-6

SHIPPING ADDRESS: 22129V* S. VERMONT AVE\ TORRANCE, CA 90502 !

364

BYTE March 19B1

Circle 325 on Inquiry card.

HOT WINTER PRICES ON PERSONAL COMPUTERS AND COMPONENTS.

Look at this!

,,.

Ohio Scientific Superboard II

$299

• It's the first complete computer system on a board.

• Superboard II uses the ultra powerful 6502 Microprocessor

• 8K Microsoft BASIC-in-ROM

• 4K static RAM on board, expandable to BK

• Full 53-key keyboard, with upper and lower case. Plus user expandability.

• Video interface and audio cassette interface.

The Ohio Scientific Superboard II at $299 — in today's economy — has got to be the best buy by far. It will entertain you with spectacular graphics made possible by its ultra high resolution graphics and super fast BASIC. It will help you in school or industry, as an ultra powerful scientific calculator. Advanced scientific functions and a built-in "immediate" mode allow you to solve complex problems without programming.

The Superboard II can be expanded economically, for business uses, or to remotely control your home appliances and security. Even communicate with other computers.

Read what's been written about Superboard II:

"We heartily recommend Superboard II for the beginner who wants to get into microcomputera with a minimum coat. A real computer with full expandability."

—POPULAR ELECTRONICS, MARCH 1979

"The Superboard II ia an excellent choice for the peraonal computer enthusiast on a budget."

-BYTE, MAY 1979

Look at these easy hardware prices:

610 Board For use with Superboard II and Challenger 1 P.

BK static RAM. Expandable to 24K or 32K system total.

Accepts up to two mini-floppy disk drives. Requires + 5V

@4.5 amps. S 298

Mini-Floppy Disk Drive Includes Ohio Scientific's PICO COS

software and connector cable. Compatible with 610

expander board. Requires + 12V @ 1.5 amps and + 5V @

0.7 amps. [Power supply S. cabinet not included.] 299

630 Board Contact us for important details. 229

AC-3P 12" combination black and white TV/video monitor. 159

4KP 4K RAM chip set. 79

PS-005 5V 4.5 amp power supply for Superboard II. 35

PS-003 12V power supply for mini-floppies. 29

CS-600 Metal case for Superboard II, 610 and 630 board

and two power supplies. [While stock lasts.] 49

CS-900B Metal case for single floppy disk drive and power

supply. [While stock lasts.] 49

AC-12P Wireless remote control system. Includes control console, two lamp modules and two appliance modules, for use with 630 board. 175

AC-17P Home security system. Includes console, fire

detector, window protection devices and door unit for use

with 630 board. 249

C1P Sams C1P Service manual 8

C4P Sams C4P Service manual 16

C3 Sams Challenger III manual 40

Ohio Scientific and independent suppliers offer hundreds of programs for the Superboard II, in cassette and mini-floppy form.

FrBight Policies Allordersof£100ormoreere shipped flight prepaid. Orders of less then SI QQ please add $4.00 to caver shipping costs. Ohio residen s adds.5% Sales Tax.

VISA

€5*

Hours: Call Monday thru Friday. 8:00 AM to 5:00 PM E.O.T. TOLL FREE: 1-800-321-5805

Guaranteed Shipment

Cleveland Consumer Computers 5. Components guarantees shipment of compu er sys ems within 48 hours upon receipt of your order. Our failure to snp within 48 hours ontitlss you to S3 5 of softwsre, FREE.

To Order: Or to get our free catalog CALL 1-800-321-5805 TOLL FREE. Charge your

order to your VISA or MASTER CHARGE account. Ohio residents call: [216] 464-8047. Or write, including your check or money order, to the address listed below.

CLEVELAND CONSUMER COMPUTERS & COMPONENTS

P.O. Box 46627 Cleveland, Ohio 44146

I I I I I

I I I I

I

Onrlian Cnpm> Cleveland consumer

Ul UCI rill lie COMPUTERS & COMPONI

P.O. Box 46627 , COMPONENTS Cleveland, Ohio 44146

D Superboard II $299. D 630 Board SS299.

D 610 Board $298. □ AC-3P 12" B/W Monitor $159.

□ Mini-Floppy Disk Drive $299. D 01P Sams Manual $8.

[Attach separate sheet for other items.]

NAME

ADDRESS:

CITY: PHONE:

STATE:

ZIP:

Payment by: VISA

MASTER CHARGE

MONFY DRDFR

Credit Card Account #

Expires.

.Interbank #[Master Charge]

TOTAL CHARGED OR ENCLOSED $.

. [Ohio Residents add 5.5% Sales Tax]

Orders of less then $100, please add $4.00 to cover shipping costs.

All orders shipped insured UPS unless otherwise requested. FOB Cleveland, Ohio.

Circle 326 on Inquiry card.

BYTE March 1981

365

ok™®®^©!]^©

□ □□

INTRODUCTORY G PRICE ONLY

REGULAR $3250.00 LIST INCLUDING CP/M2.2®

320K

MINI DRIVES SHOWN. 8"

and 554" 10MB HARD DISK OPTIONAL

IMMEDIATE DELIVERY!

1 YEAR PARTS WARRANTY!

(90 DAYS ON DRIVE PACKAGE, KEYBOARD AND LABOR)

ftfjfj. MICR0 SALES

S-100-8

©KH§©K ™i

TERMINAL

• Feather Touch Capacitance Keyboard

• 60 Key Standard ASCII PLUS + Hex Keypad

PLUS + 8 Special Function Keys PLUS + 20 Screen Editing Keys

• SO ROC Type Screen Attribute Set

• Half Intensity

COMPUTER

8SlotS-100

64K Dynamic Ram

4MHZ Z-80

Serial Printer Port (150- 19.2K)

Double Density Disk Controller

Programmable Baud Rate

Programmable Keyboard Set

0

D

DISK STORAGE

• Dual Double Density 5% Single Sided Drives

• DOUBLE SIDED Option

• Double Sided, 77 Track, Option

• Color Matched Enclosure

• Self Contained Power Supply

OPTIONS:

♦ Dual 5%" Double Sided MPI B51 (640K) add $225.00

♦ Dual 5%" Double Sided MPI B91 (1.2MB) add $360.00

♦ Dual 8" SIEMANS FDD120-8 Drives (1MB) add $250.00

♦ Dual 8" QUME Double Sided Drives (2MB) add $625.00

CP/M2.2 is a Registered Trademark of Digital Research Inc.

DEALS □ DEALS □ 0£>US

OUR BUYERS ARE IN

CONTACT WITH EVERY MAJOR

SUPPLIER AND O.E.M.

BUY HERE AT 1000 PIECE

QUANTITY PRICES

ALL MERCHANDISE 100%

GUARANTEED! 15 DAY FULL

CASH REFUND!

WRITE FOR FULL CATALOG!

664 N. MICHIGAN AVE. * SUITE 1010 * CHICAGO, ILLINOIS 60611

CALL TOLL FREE: 1-800-435-9357 * MONDAY thru SATURDAY

(ILLINOIS RESIDENTS CALL: 815-485-4002) * 8:00 a.m. to 6:30p.m.

TERMS: Prepayment - C.O.D. up to $100.00 - M/C, Visa

Please allow personal check to clear before shipment.

JUST HOT STUFF

POWER SUPPLIES

(f you can beat these prices we will be truly amazed. OEM's at 500 lot pay more than this. Call or write for full spec, sheets.

DISK POWER SUPPLIES

PRIAM-SHUGART-CENTURY-MICROPOLIS

+5V@9A |-5V@.8A [+24V@7A ] US-384 189.00

SHUGART-SIEMANS-MPI 5%"

+5V@.5A

+12V@.9A

US-340

33.50

+5V @ 2A

+12V@4A

US-323

56.25

SHUGART-SIEMANS-CDC 8"

+5V@1A

-5V@.5A

+24V@1.5A

US-205

52.50

+5V@2A

-5V@.5A

+24V @> 3A

US-206

69.00

+5V 6> 3A

-5V@.6A

+24V @ 5A

US162

89.00

+5V@1.7A

-5V@>1.5A

+24V @ 2A

US-272

69.00

+5V @ 2A

+ I2V@.4A

-12V<°>.4A

US-HTAA

37.50

TELEVIDEO 912C

SOROCIQ120-$675.00 Televideo 912C- 665.00 Televideo 920C- 720.00 ADDS R 25 - 710.00

Also have920C, SOROC, HAZELTINE, etc. What we don't have is room on this page. Call Toll Free 800 number for prices.

C-ITOH PRINTER

$499.00

Look closely at the

photo and see other

adds in this rag at

$995.00. Perfect units,

warranteed. Only 500 pes. Same story,

manufacturerer had too many.

S-100 CARD EXTENDER

$12.50

(Gold Contacts)

As long as there is a price war, we will fight your battle. Compare at your local Dept. store and buy U$ MICRO.

MEM0REX - VERBATUM - WABASH BASF FLOPPIES

BOX OF 10 ONLY:

5'/."

5%"

5%"

8"

8"

8"

SOFT HARD 10 HARD 16 SOFT 1D SOFT 2D SOFT 2DDS

$2.65 ea? 2.65 ea. 2.65 ea. 3.25 ea. 3.85 ea. 5.00 ea.

3*

SPECIAL OF THE QUARTER SPECIALS OF THE MONTH

S1-MOD (KIT)

$189.00

8®r

Complete S-100 12 Slot Computer. Ample system powerwith regulated power for drives. Excellent for Subsystem or Hobby use. 4 hours to build. (6 conn, inch, less fans)

DUAL DRIVE SUBSYSTEM

$995.00

$195.00 w/no Drives

If this looks like a Lobo Drive System, don't be fooled. Just because it looks like one, works like one, smells like one,

m±=r

2SHUGART801R POWER SUPPLY

and tastes like one (?) doesn't mean it has to cost like onel

EXPANDABLE RAM

*SPECIAL*SPECIAL*SPECIAL*

This is the best all around 64K board you can buy. If after you see it, you don't agree return for full refund. Bank Select by extended address lines or I.O. 40H.

* $389.00 A &T*

S-100 POWER $79.50

Simple Brute Force!

S-100 Power Supply,

30A@ +8V,

6A@>+16V,

6A@>-16V,

PC Board Design.

Z-80 CPU (KIT)

The first time this

world popular CPU

offered in Kit. 2 serial,

3 parallel, CTC, EProm

Z-80 at 4 mhz. Software

buad rate, etc. (less Prom fit cable)

$212.00

12 SLOT MOTHER

We have connectors and power supply too. Start your system with quality components. Terminated.

$22.50

CONNECTORS $2.50 ea.

FANS $14.95

0

These are brand new,

in the box fans. Not

noisey bearing pull outs.

Never again at these low prices!

3-1/8'

4-5/8"

4116s

Expansion 16K Dynamic RAMs for Apple, TRS-80 S-100 systems. T.I., Mostek Intel, Call for manufacturer.

$3.75

200 NS

DIP 80 $399.00

Don't be mislead by this Jg LOW price. This is a rug- Iji ged 100% Duty Cycle ■ 7 by 7 Dot Matrix Printer. MMMMM Brand new, factory warr. I ^—

• RS-232 ADD $65.00 • TRACTOR FEED ADD $70.00

2114s

One of the world's two.

most popular STATIC ., M

RAMs. Factory prime yjr 200 NS

tested units. Sold in lots of 8 only.

FUJITSU, HITACHI, etc.

$3.45

TMS-4044 MM-5257 INTEL 2147

$4.25

250 NS

The other of the world's most popular STATIC RAMs. This one is 4K by 1 organization. Don't buy Gold, buy these, the price won't last!

2716s 2708s

$9.50 (450 NS) $6.95 (450 NS)

Remember when 2716s were $50.00 and hard to get? These units are so beautiful it's hard to part with them. But we will, for a small price. Guaranteed!

SHUGART DRIVE 8" 801R

$395.00

Manufacturer had

too many, buys at 8" 851 R $585.00

1000 piece rate,

sales dropped, so we got'em. Fantastic buy, get

them while they last! Full warranty.

SIEMANS DRIVE

8" 120-8

$375.00

Very Special Price on

these BRAND NEW current production units

Add $10.00 for Extended 1 Year Warrantee!

Circle 327 on inquiry card.

BYTE March 1981

367

I SN7400N I SN7401N I SN7402N

| SN7403N SN7404N SN74Q5N SN7406N SN7407N SN7408N SN74Q9N SN7410N SN7411N SN7412N SN7413N SN7414N SN7416N SN7417N SN7420N SN7421N SN7422N SN7423N SN742SN SN7426N SN7427N 5N7429N SN7430N SN7432N SN7437N 5N743SN SN7439N SN7440N SN7441N 5N7442N SN7443N SN7444N 5N7445N SN7446N SN7447N SN7448N SN7450N SN74S1N SN7453N SN7454N SN74S9A 5N7460N 5N7470N

74LSOO 74LS01 74LS02 74LS03 74LS04 74L505 74LSD8 74LSQ9 74L510 74L511 74LS12 74LS13 74LSI4 74LS15 74LS20 74LS21 74LS22 74LS26 74LS27 74LS2B 74L530 74L532 74LS33 74LS37 74LS3B 74LS40 74LS42 74LS47 74L548 74LS49 74L551 74LSS4 74LS55 74LS73 74LS74 74LS75 74LS76 74LS7B 74L5S3 74LSB5 74LS86 74LS9Q

7400

SN7472N SN7473N SN7474N SN7475N SN7476N SN7479N SN7480N SN74B2N SN7483N SN748SN 5N7486N SN74B9N SN749QN SN7491N SN7492N SN7493N SN7494N SN7495N SN7496N SN7497N SN7410ON SN74107N SN74109N SN74116N SN74121N 5N74122N SN74123N SN74125N SN74126N SN74132N SN74136N 5N74141N SN74142N SN74143N SN74144N SN74145N SN74147N SN7414BN SN741S0N 5N74151N SN74152N SN74153N SN741S4N SN741SSN

3.25 3.49 3.49

SN74156N SN74157N SN74160N SN74161N SN74162N SN74163N 5N74154N SN7416SN SN74166N SN74167N SN74170N SN74172N SN74173N SN74174N SN74175N SN74176N SN74177N SN74179N SN741BON SN741B1N SN741B2N SN741B4N SN7418SN SN7419QN SN74191N SN74192N SN74193N SN74194N SN74195N SN74196N SN74197N SN7419BN SN74199N SN74221N SN742S1N SN74276N 5N74279N SN74283N SN74284N 5N742B5N 5N7436SN SN74366N SN74367N SN74368N SN74390N SN74393N

.59

74LS

74LS92 74LS93 74LS95 74LS96 74LS107 74LS109 74LS112 74LS113 74L5114 74L5122 74L5123 74LS125 74LS126 74LS132 74L5133 74L5136 74LS13B 74LS139 74L5151 74LS153 74L5154 74LS155 74L5156 74LS157 74L5158 74L5160 74L51G1 74LS162 74LS163 74L5164 74L5165 74LS16B 74L5169 74LS170 74LS173 74LS174 74LS175 74L51B1 74LS190 74L5191

74LS192

74LS193

74L5194

74LS195

74LS197

74LS221

74L5240

74LS241

74L5242

74LS243

74L5244

74LS245

74L5247

74LS24B

74L5249

74LS251

74LS2S3

74LS2S7

74L52S8

74LS26Q

74LS266

74LS273

74LS279

74L52B3

74LS290

74L5293

74L529B

74LS3S2

74LS353

74L536S

74LS366

74L5367

74LS3&3

74L5373

74LS374

74LS375

74LS386

74LS393

74LS399

74L5670

S1L595

81LS97

74SOQ .50

74502 .50

74503 .50

74504 .55

74505 .55

74508 .50

74509 .50

74510 .50

74511 .50 74515 .50 74520 .50 74522 .50 74530 .50 74S32 .55 74S40 .55 74551 .50 74S64 .50 745G5 .50 74574 .79 74SS6 .79

745112 .79

745113 .79

745114 .79

• LIMITED A\

74S

745133

745134 74513S 745136 74513B 745139 74S140 745151 745153 745157 745158 745174 745175 745188 745194 745195 74S19G 745240 74S241 745242 745243 AILABILITV

745244 745251 745253

745257 74S258 745260 7452B0 74S2B7* 745268* 745373 745374 745387* 745471* 74S472* 745473* 74S474* 745475* 745570* 745571 * 745572* 745573* 745940 745941 HE5E PROr

2.49 2.49 2.49

19.95 19.95 19.95 21.95 21.95 7.95 7.95 19.95 19.95

CA3013H CA3023H

CA3039H CA3W6N CA3059N CA306QN CA3080H

2.15

CA-LINEAR

CA3081N 2.00

CA3DS2N 2.00

CA3083N 1.60

CA3086N .85

CA30B9N CA3096N CA3130H CA3140H CA3160H CA3401M CA3600N

CD4000 CD4001 CD4002 CD4006 CO4007 CD4009 CD4010 CD4011 CD4012 CD4013 CD4014 CD4015 CD4016 CD4017 CD401B CD4019 CO4020 CD4021 CD4022 CD4023 CD4024 CD4025 CO4026 CD4027 CO402B CD4029 CD4030 CD4035 L CD4O40

CD-CMOS

CD4041 CD4042 CD4043

CD4044 CD4046 CD4047 CD404B CD4049 CD405O CD4051 CO4052 CD4053 CD4056 CD4059 CD40S0 CD4066 CD4068 CD4069 CD4070 CD4071 CD4072 CD4073 CD4075 CD4076 CD4QB1

CO40B2

CD4093

CD409B

CD4506

CD4SQ7

CD4508

CD4510

CD4511

CD4514

CD4515

CD4516

CD451B

CD4519

CD4520

CD4526

CD452B

CD4529

CD4543

CD45G2

CD4S66

CD4583

CD4723

CD4724

MC144W

MC14410

MC14411

MC14412

MC14419

MC 14433

1.29 3.95 2.95

11.95 2.79 2.49

14.95 14.95 14.95 11.95 4.9S 13.95

LITRONIX DISPLAY SALE

MULTI DIGIT REFLECTOR ARRAYS FOR

'■"»-'

&

rOLARITV

nmmm

u»tt«umn

FOHIYAHO VOLT»Gr

IS;:;'

™»

TYP

MIN

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MA.

OL4MJl"2!

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WSL

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2.49 2.49

Sl«™ ti

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■*

J

4.9S 4.9S 2.49

DL41MA|r,dl

,.0

C.C....MPX

IS

3

3*

40

4.9S

MULTI DIGIT REFLECTOR A!

DlZJOQtR.II

M

CC.HPX

ISn JO.g.lDP R>*l

M

.1

W

a

:o

M

.99

OLC 143* (b-i^I

50

C.A MPK

ttHionn

IS

:■..

35

' 15

1.49

OL4SMIHMI

W

C.CMPX

>Sq4D*lD.F.H.|ni

s

5

10

17

10

30

2.49

DLSMdlHHI

50

cawra

IStt SOHpl DP Righl

e

5

10

1.7

10

30

2.95

01«» IXMI

Uj

C* MPX

'>, i, [j.(,. n " H vi

8

&

10

17

ID

30

2.S3

MWflM

10

c^im

J Sn a d»i o p B,oh.

US

U

,0

34

40

30

3.99

DISCRETE LEDS

XC556R .200" red

XC556G .200" green

XC556V .200" yellov

XC556C .200" clear

XC22R .200" red

XC22G .200" green

XC22Y .200" yellov

B/H

4/11 4/11

4/11

S/Sl 4/11 4/11 4/11

MV50 .085" red

XC209R .125" red

XC209G .125" green

XC209Y .125" yellow

XC526R .185" red

XC526G .185" green

XC526Y .IBS" yellow

XC526C -IBS" clear

6/11

s/ii

4/$l 4/11 5/S1 4/J1 4/11 4/11

XC111R .190" red S/Jl

XCU1G .190" green 4/J1

XC111Y ;I90" yellow 4/J1

XC1I1C .190" clear 4/11

^

RL-2 . .S.39ea.or3/$1.00

C.A. —

Type MAN 1 MAN 2 MAN 3 MAN 52 MAN 54 MAN 71 MAN 72 MAN 74 MAN82 MAN 84 MAN 3620 MAN 3630 MAN 3640 MAN 4610 MAN 6610 MAN 6630 MAN 6G40 MAN 6650 MAN 6660 MAN 6710 MAN 6750 MAN 6780 DLD304 OLD307 DLGSO0

Polarity C.A.—red 5x7 D.M.—red C.C.-red C.A.— green C.C.—green C.A.—red C.A.—red C.C.-red C.A.-yellow C.C.—yellow C.A.—orange C.A.— orange ± 1 C.C.—orange C.A.—orange C.A.— orange— DD C.A.-orange ± 1 C.C.—orange—DD C.C.—orange i 1 C. A.— orange C.A.—red—DD C.C.-red ± 1 C.C.-red C.C.—orange C.A.—orange CO—green

DISPLAY LE0S "-«™

Type

DLG507

DL704

DL707

DL72B

DL741

DL746

DL747

DL750

DLDS47

DLO850

DL33B

FND358

FND359

FND503

FND507

HDSP-3401

HDSP-3403

SOB2-77S1

5OB2-7760

50B2-730O

5032-7302

5082-7304

4N28

LIT-1

MOC3010

Polarity

C.A.— green .5

C.C.-red .3

C.A.—red .31

C.C.-red .5

C.A.—red .6

C.A.—red t l .6

C.A.—red .6

C.C.-red .6

C.A.—orange .8

C.C.—orange .8

C.C.-red .1

C.C. t 1 .3

C.C. .3

C.C. (FNDSOO) .5

C.A. (FNDS10) .5

C.A.—red .8

C.C.-red .B

C.A.,R.H.D.—red .4

C.C.R.H.D.—red .4

4x7sgl.dlg. RHD .6

4x7sgl.dlg. LHD ,6

Overnge.char.Ul) .6 Photo XslstorOpto-l Photo Xslstor Opto-I Optically Isoi.TrlacD

22.00 22.00 19.95

POTENTIOMETERS

$2.95 each

vieets Mll-R-94

RV4NAY SD

102A

IK

RV4NAY SD

502A

5K

RV4NAY SD

103A

10K

RV4NAY SD

253A

25K

RV4NAY 5D

M3A

SDK

RV4NAY SD

I04A

100K

RV4NAY SD

105A

lMeg

LOW PROFILE

(TIN) SOCKETS

8 Pin LP 14 pin LP 16 pin LP IB pin LP 20 pin LP 22 pin LP 24 pin LP 2B pin LP 36 pin LP 40 Pin LP

SOLDERTAIL (GOLD) STANDARD

8 pin 5G 14 pin SG 16 pin SG 18 pin SG 24 Pin SG 2B pin SG 36 pin SG 40 pin 5G

$1.35 each

3/4 Wan @) 70°C 1 5 turn pot. Linear taper. Printed circuit mount.

Part No. Pai

830P-50ohm S30P-100ohm _830P-SOOohm 830P-1K B30P-2K

E£j|jte

830P- 5K 83OP-10K B3OP-20K S30P-50K

83OP-1O0K B30P-200K B3QP-5O0K 830P-lMeg

SOLDERTAIL

STANDARD (TIN)

14 pin ST 16 pin ST IB pin ST 24 pin ST 28 pin ST 36 pin ST 40 Pin ST

WIRE WRAP SOCKETS (GOLD) LEVEL #3

S pin

WW

.59

10 pin

WW

.69

14 plr

WW

.79

16 pin

WW

-B5

18 pin

WW

.99

20Pin

WW

1.19

22 pin

WW

1.49

24 pin

WW

1.39

2B pin

WW

1.69

36 Pin

WW

2.19

40 pin

WW

2.29

1/4 WATT RESISTOR ASSORTMENTS -5%

ASST. 1

Sea.

10 Ohm 27 Ohm

12 Ohn

3.1 On

15 Ohm

39 Ohm

18 Dhm 47 Ohm

22 Ohm

56 Ohm

50 pes.

$1.95

ASST.2

5ea.

68 Ohm 180 Ohm

82 Ohn 220 Ohn

l 100 Ohm 270Ohm

120 Ohm 330 Ohm

ISO Ohm 390 Ohm

50pcs.

$1.95

ASST. 3

5ea.

470 Ohm 560 Ohm 680 Ohm 820 Ohm 1.2K 1.5K UK 2.2K

IK 2.7K

50 pes.

$1.95

ASST. 4

Sea.

3.3K

8.2K

3.9K

10K

4.7K 12K

S.6K 15K

6.BK 18K

50 pes.

$1.95

ASST. 5

5ea.

22K 56 K

27K

6SK

33K 82K

39K

10OK

47K 120K

50 pes.

$1.95

ASST. 6

Sea.

150K 390K

iaoK

470K

220K

560K

270K

680K

330K

S20K

50 pes.

$1.95

ASST. 7

5ea.

1M 2.7M

1.2M 3.3M

1.5M 3.9M

l.SM 4.7M

2.2M 5.6M

50 pes,

$1.95

ASST. 8 R

Includes Resistor Assts. 1-7 (350 pes.)

$10.95 ea.

$10.00 Min. Order - U.S. Funds Only Calif. Residents Add 6% Sales Tax Postage-Add5%plusSl Insurance

ameco

ELECTRONICS

Spec Sheets- 25rf

Send 41d Postage for your

FREE 1981 JAMECO CATALOG

PHONE

ORDERS

WELCOME

(415) 592-8097

MAIL ORDER ELECTRONICS - WORLDWIDE

1355 SHOREWAY ROAD, BELMONT, CA 94002

PRICES SUBJECT TO CHANGE

Part No.

7045IPI

JWSCV/KIt*

7106CPL

7106EV/KH*

7107CPL

71Q7EV/Klt*

7116CPL

7117CPL

7201IDR

7205IPG

726 EV/Kit*

7206CJPE

7206CEV/KU'

7207 A IPD

7207AEV/Kit'

7303IPI

7209IPA

7215IPG

721SEV/Kit*

7216AIJI

7216CIJI

7216 DIP I

72171 Jl

7218CIJI

7224 [PL

7226AIJL

7226AEV/KU

7240IJE

7242IJA

72S0UE

7260IJE

7555 IP A

7556IPD

7611BCPA

7612BCPA

7621BCPA

7631CCPE

7641CCPD

7642CCPD

7660CPA

S069CCQ

8211CPA

8212CPA

• INT

DtMlRli^DlL

Puncti

CMOS Precision Timer Stopwatch Chip, XTL 3Vl Digit A/D (LCD Drive) IC, Circuit Board, Display 3Vi Digit A/D (LED Drive) IC, Circuit Board. Display 3W Digit A/D LCD OtS. HLI 3Vz Digit A/D LED Dis.

attery ^

sit I

oicato

alor

Price

14,95 22.95 16.95 34.95 15.95

2i.«

18.95 17.95 2.25 12.95 19.95 5.15 9.95

Tone Generator Chip, XTL

Dscillator Controller

Freq. Counter Chlo, XTL

Seven Decade Counter

Clock Generator

4 Func. CMOS Stopwatch CKT

4 Func. Stopwatch Chip, XTL 8-Diglt Univ. Counter C.A. S-Dlglt Freq. Counter C.A. 8-Diglt Freq. Counter C.C. 4-Diglt LED Up/Down Counter 8-Dlglt Univ. LED Drive LCD4V1Dlglt UpCounterDRI 8-Digtt Univ. counter

5 Function Counter Chip, XTL CMDS Bin Prog. Timer/Counter CMOS DWIde-Dy-256 RC Timer CMDS BCD Prog. Timer/Counter CMOS BCD Prog. Timer/Counter CMDS555Timer (8'plnJ CMDS 556 Timer £14 pin) CMDS Op Amp Comparator 5MV 2.25 CMOS Op Amp Ext. Cmvr. 5MV 2.95 CMOS Dual Op Amp Comp. SMV 3.95 CMOS Trl Op Amp Comp. 10MV 5.35 CMOS Quad Op Amp Comp. 10MV 7.50 CMDS Quad Op Amp Comp. 10MV 7.50 Voltage Converter 2.95 SOppm Band—GAP Volt Rel. Diode 2.50 Volt Ref/lndicator 2.50 Volt Ref/lndlcator 2.50

ERSIL'S EVALUATION KITS

26.95 21.95 12.95 10.95 11.25 31.95 74.95 4.95

2.20

74C0Q

74C02 74CW 74C0S 74C10 74C14 74C20 74C30 74C42 74C4B 74C/3 74C74 74CB5 74C86 74C89 74C90 74C93 74C95

.39

74C

74C106

74C107 74C151 74CI54 74C157 74C160 74C161 74C162 74C163 74C164 74C173 74C174 74C175 74C192 74C193

2.95 3.95 2.25

74C195 74C221

74C240 74C244 74C373 74C374

74C901 74C903 74C911 74C912 74C915 74C917 74C922 74C923 74C92S 74C926 S0C95 B0C97

2.25 2.25 2.49 2.59

.79

LH0002CN

LM10CLH

LM11CLH

LH0070-OH

TL071CP

TL072CP

TL074CN

LH0082CD

TL082CP

TLD84CN

LH0094CD

LM300H

LM301CN

LM302H

LM304H

LM30SH

LM307CN

LM30BCN

LM309H

LM309K

LM310CN

LM311H

LM312H

LM317MP

LM317T

LM317K

LM318CN

LM319N

LM320K-5

LM320K-12

LM320K-15

LM320T-5

LM320T-12

LM320T-15

LM323K-5

LM324N

LM329DZ

LM331N

LM334Z

LM33SZ

LM336Z

LM337T

LM337MP

LM33BK

LM339N

LM340K-5

LM340K-12

LM340K-15

4.50 4.75 6.05 .79 1.39 2.49 35.80

LINEAR

LM340T-5

LM34QT-12

LM340T-15

LM341P-5

LM341P-12

LM341P-15

LM342P-5

LM342P-12

LM342P-15

LM348N

LM3S0K

LF3S1N

LF353N

LF35SN

LF356N

LM35BN

LM359N

LM370N

LM373N

LM377N

LM3B0N

LM3B1N

LM382N

LM384M

LM3S6N-3

LM387N

LM389N

LM392N

LF39BN

LM399H

TL494CN

TL496CP

NE510A

NE529A

NE531H

NE536H

NE540H

NE544N

NE550A

NE555V

LM5S6N

NE564N

LM565M

LM566CN

LM567V

6.00 4.95 3.95

4.95

NE570N

LM702H

LM703CN .89

LM709N .29

LM710N .79

LM711N .79

LM723N .69

LM733N 1.00

LM739N 1.19

LM741CN .35

MC1741SCG 3.00

LM747N .79

LM74BN .59

LM10i4N

LM1310N

LM1458CN

LM1488N

LM14B9N

LM1496N

LM1556V

LM1B00N

LM1877N-9

LM1889N

LM1896N

LM2O02T

LM2B77P

LM2878P

LM2896P-1

LM3189N

LM3900N .69

LM3905CN 1.25

LM3909N 1.15

LM3914N

LM3915N

LM3916N

RC4136N

RC4151NB

RC4194TK 5.95

RC419STK 5.49

KB442B

KB4429

LM4500A

ICLS038B

LM13080N

LM1360ON

7513SN

75450N

75451CN

2.75

2.95 3.25 3.20

2.05 2.25 2.25 2.95

3.95 3.95 3,95 1.25 3.95

4.25 5.95 3.25 4.95 1.29 1.49

CAPACITOR CORNER

50 VOLT CERAMIC DISC CAPACITORS

10 pf 22 P( 47 pf 100 pf 220 Pf 470 Pi

19 10-99 100 +

.06 .06 .05 .06 .06 .05

.004 7uF

,0UiF

.Q22J1F

-047uF

■IMF

1-9 10-99 100*

.09 .07 .06

100 VOLT MYLAR FILM CAPACITORS

.OOlmf ,12 .10 .07 I .022mf .13 .11 .0B

.D022mf .12 .10 .07 .047mf .21 .17 .13

.0Q47mf .12 .10 .07 .lmf .27 .23 .17

,01mf .12 .10 .07 I .22mf .33 .27 .22

+20% DIPPED TANTALUMS (Solid) CAPACITORS

1/35V .15/35V .Z2/3SV

.33/35V .47/35V

.6B/35V 1.0/3SV

1.S/3SV 2.2/35V 3.3/2SV 4.7/HV 6.8/2SV 15/25V 22/6V

.63 .56 .45

MINI. ALUMINUM ELECTROLYTIC CAPACITORS

.47/50V

1.0/50V

3.3/50V

4.7/25V

10/25V

10/50V

22/25V

22/50V

47/25V

47/50V

100/25V

lOO.'SOV

2M/25V

220/50V

470/25V

10O0/16V

2200/16V

Axial Lead

.47/25V

.47/SOV 1.0/16V 1.0/25V 1.0/SOV 4.7/16V 4.7/25V 4.7/50V 10/16V 10/25V 10/50V 47/SOV 100/16V 100/25V 100/50V 220/16V 470/25V

368

BYTE March 1981

Circle 328 on inquiry card.

AaSLoorClock Modules

12VDC

AUTOMOTIVE/

INSTRUMENT

CLOCK

APPLICATIONS:

* In-dash au toclocks ■ After-market auto/

RV clocks

• Aircraft-marina elks

Features: Bright 0.3" green display. Internal crystal timebase, t 0.5 sec/day accur. Auto, display brightness control logic. Display color filterable to blue, blue-green, green fit yellow. Complete—just add switches and lens.

MA 1003 Module $16.95

MA 1023.7" Low Cost Digital LED Clock Module 8.95

MA1026 .7"Dig.LED Alarm Clock/Thermometer 18.95

MA5036 .3" Low Cost Digital LED Clock/TimBr 6.95

MA1002 .5" LED Display Dig. Clock fit XforrriBr 9.95

'2 National Semiconductor

RAM SALE

MM5290N-4 (mk4H6/upd416) . - $4.95 each

16K DYNAMIC RAM (250NS)

(8 EACH S39.95) (100 EACH S<J50.00/lot)

MM5290J-2 (MK4H6/UPD416) . . $6.95 each

16K DYNAMIC RAM (150NS)

(8 EACH S49.95) (100 EACH S550.00/lot)

MM5298J-3A $3.25 each

MM2114-3 $5.95 each

MM2114L-3 $6.25 each

4K STATIC RAM (LOW POWER 300NS) (8 EACH S44.95) (100 EACH Sd75,00/lot)

EPROM Erasing Lamp

• Erases 2708, 2716, 1702A, 5203Q, 5204Q, etc.

• Erases up to 4 chips within 20 minutes.

• Maintains constant exposure distance of one inch.

• Special conductive foam linereliminates static build-up.

• Built-in safety lock to prevent U V exposure.

• Compact - only 7-5/8" x 2-7/8" x 2"

■ Complete with holding tray for 4 chips.

UVS-11E $79.95

Jumbo 6-Digit Clock Kit

• Four.630"ht. and two .300"ht. common anode displays

• Uses MM5314 clock chip

• Switches for hours, minutes and hold functions

• Hours easily viewable to 30 feet ■ Simulated walnut case

• 115VAC operation

• 12 or 24 hour operation

• Includes all components, case and wall transformer

• Size: 6%" x 3-1/8" x 1%"

JE747 $29.95

6-Digit Clock Kit

• Bright .300 ht. □ de display

•Uses MM5314 cl

• Switches for ho and hold modes

• Simulated walnut

• 115 VAC operatic

• 12 or 2d hr. opera

able to 20 ft.

JE701 $19.95

Regulated Power Supply

Uses LM309K. Heat sink ^fc-. \

provided. PC board con- — struction. Provides a solid 1 amp @ 5 volts. Can supply up to ±5V, *9V and ± 12V with JE205 Adapter. Includes components, hardware and instructions. Size: 3'/a" x 5" x 2"H

JE200 $14.95

ADAPTER BOARD - Adapts to JE200±5V, ±9Vand ±12V

DC/DC converter with +5V input. Toriodal hispeed switching XFMR. Short circuit protection. PC board construction. Piggy-back to JE 200 board. Size: 3W x 2" x 9/16"H

. JE205 $12.95

MICROPROCESSOR COMPONENTS

DPKSt

- 6800/6800 SUPPORT DEVICES

P8085 CPU

INSB900 CPU-;

TMSWMJL MPU

.-.;,vw.

flMMlH 1M50&H

■ SHIFT REGISTERS

DATA ACQUISITION

-DATA ACQUISITION (CONTINUED)

?M«4 Static

I DM ■) Sialic

lOMx] Static

Ettx* Static

256x4 Static MOS

10M>4 Sialic 450m

1024x4 Sialic 450ns Low Power

IcWOmlhcui

IrUBI.) 16k Dy J0»»] I 2Wx4 S

UPD4H/MK4027 «K Dynamic 16-pin TMS40444SNL 4K Static TMS404S 1024x4 Stalk

PROMS/EPROMS

SK EPROM

NMOS READ ONLY MEMORIES

MCM66J10P ITBxSxl ASCII Smilea w/Qieeb

MCM66JJ0P 12S*9x/ Math SymDol & Pictures

WCM667S0P 128x9x7 Aloha. Control Char. Con.

MICROPROCESSOR MANUALS"

- SPECIAL FUNCTION

COP402N COM02MN

HSeg.VAC Flgor. Driver (JO-Oin pki

TELEPHONE/KEYBOARD CHIPS

DESIGNERS'SERIES Blank Desk-Top Electronic Enclosures

High strength epoxy molded end pieces in mocha brown finish.

Sliding rear/bottom panel for service and component accessibility.

Top / bottom panels .080 thk alum. Alodine type 120D finish {gold tint color) for best paint adhesion after modification.

Vented top and bottom panels for cooling efficiency. Rigid construction provides unlimited applications.

CONSTRUCTION:

The "DTE" Blank Desk Top Electronic Enclosuresare designed to blend and complement today's modern computer equipment and can beused in both industrial and home. The end pieces are precision molded with an internal slot (all around) to accept both top and bottom panels. The panels are then fastened to V thick tabs inside the end pieces to provide maximum rigidity to the enclosure. For ease of equipment servicing, the rear/ bottom panel slides back on slotted tracks while the rest of the enclosure remains intact. Different panel widths may be used while maintaining a common profile outline. The molded end pieces can also be painted to match any panel color scheme.

Enclosure Model No.

Panel Width

PRICE

1 DTE-8

8.00"

$29.95

DTE-11

10.65"

$32.95

! DTE-14

14.00"

$34.95

S10.00 Min. Order - U.S. Funds Only Calif. Residents Add 6% Sales Tax Postage—Add 5%plusSl Insurance

Spec Sheets - 25c1

Send 414 Postage for your

FREE 1981 JAMECO CATALOG

PHONE

ORDERS

WELCOME

(415)592-8097

MAIL ORDER ELECTRONICS - WORLDWIDE

1355 SHOREIAIAY ROAD, BELMONT. CA 94002

PRICES SUBJECT TO CHANGE

JOYSTICKS

I JVC-40

JS-5K 5K Linear Taper Pots S5.25

JS-100K 100K Linear Taper Pots $4.95

JVC-40 40K (2) Video Controller in case . . . S5.95

AC and DC Wall Transformers

Pan No. Input Output Price

AC 250 1l7V/60Hz 12 VAC 250mA S3.95

AC 500 117V/60Hz 12 VAC 500mA S4.95

AC1000 117V/60Hz 12 VAC 1 amp S5.95

DV9200 1l7V/60Hz 9 VDC 200mA S3.25

DC 900 120V/60Ht 9 VDC 500mA S3.95

CONNECTORS

w "

DB25P D-Subminiature Plug $2.95

DB25S D-Subminiature Socket S3.50

DB51226 Cover for DB25P/S $1.75

22/44SE P.C. Edge (22/44 Pin) $2.95

UG88/U BNC Plug $1.79

UG89/U BNC Jack $3.79

UG175/U UHF Adapter $ .49

S0239 UHF Panel Recp $1.29

PL258 UHF Adapter $1.60

PL259 UHF Plug $1.60

UG260/U BNC Plug $1.79

UG1094/U BMC Bulkhead Recp $1.29

TRS-80 16K Conversion Kit

Expand your 4K TRS-80 System t o 16K. Kit comas complete with:

*8ea.MM5290(UPD416/4l16)16K Dyn. RamsCNS}

* Documentation for Conversion

TRS-16K2 -isons $49.95

TRS-16K4 -250IMS $39.95

JE610 ASCII Encoded Keyboard Kit

Si

The JE610 ASCII Keyboard Kit can be interfaced into most any computer system. The kit comes complete with an industrial grade keyboard switch assembly (62-keys). IC's, sockets, connector, electronic components and a double-sided printed wiring board. The keyboard assembly requires +5V <S> 150mA and -12V @ 10 mA lor operation. Features: 60 keys generate the 126 characters, upper and lower case ASCII set. Fully buffered. Two user-define keys provided for custom applications. Caps lock for uppercase-only alpha characters. Utilizes a 2376 (40-pin) encoder read-only memory chip. Outputs directly compatible with TTL/DTL or MOS logic arrays. Easy interfacing with a 16-pin dip or 18-pin edge connector. Size: 3&"H x 14VS"W x B»"D

JE610/DTE-AK (a5 pictured above).. .$124.95

11-j- in iy-^ 63-Key Keyboard, PC Board, a -,-. -._ JE610 Kit & Components (nocase) S 79.95

K62 62-Key Keyboard (Keyboard only) . . .$ 34.95

DTE-AK (case only-3ft-Hxll"Wx8'.VD)$ 49.95

JE600 Hexadecimal Encoder Kit

FULL 8-BIT LATCHED OUTPUT 19-KEY KEYBOARD

The JE500 Encoder Keyboard Kit provides two separate hexadecimal digits produced from sequential key entries to allow direct programming for 8-bit microprocessor or B-bit memory circuits. Three additional keys are provided for user operations with one having a bistable output available. The outputs are latched and monitored with 9 LEO readouts. Also included isa key entry strobe. Features: Full 8 bit latched output for microprocessor use. Three user-define keys with one being bistable operation. Debounce circuit provided for all 19 keys. 9 LED readouts to verify entries. Easy interfacing with standard 16-pin IC connector. Only +5VDC required for operation. Size; 3fc"H x 8V1"W x BX"D

JE600/DTE-HK (.« pictured above) ... .$99.95

irrcnn \f ■* 19-Key Hexadec. Keyboard, r>rr»r»r

JE600 Kit PC Board aCmnnts. [no case) . .$59.95

K19 19-Key Keyboard (Keyboard only) .... $14.95

DTE-HK (case only -3ft"HX«»"W««»."D) $44.95 .

Circle 328 on inquiry card.

BYTE March 1981

369

<T

COMPUTER SYSTEMS IMC.

15620 South lnglewood Avenue I.awndale. California 90260 <21.i> 970-0952

PLACE ORDERS TOLL FREE

1-800-421-5150

(CONTINENTAL U.S. ONLY)

(EXCEPT CALIFORNIA)

Retail Store Open

10:00 A.M. to 6:00 P.M.

Daily Except Sunday

QT CATALOG NOW AVAILABLE

The QT System+ is designed for both businessmen and engineers in accordance with latest IEEE standards. Among other functions, it can be used for accounting and word processing, as well as a variety of scientific applications. The system will soon be available with MP/M® to allow multi-user, multi-tasking operations. This means,forexample, that an engineer could be working on scientific applications in the lab while an accountant is writing payroll checks in .the office. QT also offers a full line of

QT SYSTEM +

business and applications software, ranging from a business package to word processing.

Technical specifications: 4MHz Z-80A CPU • Dbl-sided, dbl-den. 5'A" & 8" floppy disk controller (handles both drives simultaneously) • Includes televideo terminal • Two 8" dbl-den., sgl. or dual sided disk drives, expandable to 4 floppy drives • CP/M® 2.2 included • 64K RAM, expandable peryour requirements • Comes complete in single mainframe •

EPROM/ROM in any combination to 8K • Two RS232C serial I/O ports • Two parallel I/O ports • Hard disk compatible • Real time clock • Std. 2K monitor program & disk routines included on ROM • Power-on/Reset jump to monitor program • 2716 (5V) EPROM programmer (software incl. on monitor ROM; ext. 25.5V @ 50ma req.) • Uses Z-80A CPU •vectored interrupts • Assembled, tested & burned in at factory • Documentation included.

SYSTEM + I (1MB+)

SYSTEM + II (2MB+)

SYS+SS Computer System with 8" Single Sided Drives (801R) without Terminal

A&T (6 slot) $3495.00

A&T (8 Slot) $3595.00

A&T (12 slot) $3695.00

With Terminal Add $900.00

MINI-SYSTEM + I (V2MB+)

Computer System with 5'A" Single Sided Drives (uses B-51 Disk Drives) No Terminal

A&T (6 slot) $2495.00

A&T (8 slot) $2595.00

A&T (12 slot) $2695.00

SYS+DS Computer System with 8" Dual-Sided Drives (Qume DT-8) without Terminal

A&T (6 Slot) $4195.00

A&T (8 slot) $4295.00

A&T (12 slot) $4395.00

With Terminal Add $900.00

MINI-SYSTEM + II (1MB+)

Computer System with 5V'«" Double Sided Drives (uses B-52 Disk Drives) No Terminal

A&T (6 slot) $2795.00

A&T (8 slot) $2895.00

A

A&T (12 slot) $2995.00

J

S-100 PRODUCTS

PARTS

Double Density - Cal Comp Sys

5V." or 8" disk controller with Iree CP/M 2.2 CCS-2422A A&T $374.95

SALE SBC-100-SD Systems

2.5 MHz 280 CPU with serial & parallel I/O ports

SDS-SBC100K Kit $280.00

SDS-SBC100AT A&T $350.00

SBC-200 - SD Systems

4 MHz Z60 CPU with serial & parallel I/O ports

SDS-SBC200K Kit $348.00

SDS-SBC200AT A&T $408.00

SM-E

CB2 - S.S.M.

2 or 4 MHz switchable Z80 CPU with RAM, ROM & I/O

SSM-CB2K Kit $200.00

SSM-CB2AT A&T $275.00

2810 Z-80 CPU - C«l Comp Sys

2 or 4 MHz Z80A CPU w/serial I/O port

CCS-2810 A&T $275.00

Expando RAM II - SD Systems

4 MHz RAM board expandable Irom 16K to 256K

SDS-RAM216K 16K kit $289.95

SDS-RAM216AT 16K A&T $339.95

SDS-RAM232K 32K kit $329.95

SDS-RAM232AT 32K A&T $379.95

SDS-RAM248K 48K kit $369.95

SDS-RAM248AT 46K A&T $419.95

SDS-RAM264K 64K kit $409.95

SDS-RAM264K 64K A&T $459.95

PROM-100 - SD Systems

2708, 2716, 2732, 2758 & 2516 EPROM programmer

SDS-PROM-100K kit $220.00

SDS-PROM-100AT A&T $275.00

ITHACA AUDIO REV 2.0 Z-80 BD

Bare Board $35.00 each

10 for $300.00 A

SEALS ELECTRONICS 32K STATIC BD

Uses TMS-4044 or 5257L $35.00 each

I/0-4 - S.S.M.

2 serial I/O ports plus 2 parallel I/O ports

SSM-I04K kit $179.95

SSM-I04AT A&T $259.95

SSM-I04BB Bare board $ 35.00

Versatloppy II - SD Systems

New double density controller lor both 8" & 5W

SDS-VF2K kit $385.00

SDS-VF2AT A&.T $450.00

VDB-8024 - SD Systems

80 x 24 I/O mapped video board with keyboard I/O

SDS-VDBK kit $406.00

SDS-VDBAT A&T $475.00

VB3 - S.S.M.

80 x 24 x 48 memory mapped with graphics

SSM-VB3-4mhzK kit, 4 MHz $399.95

SSM-VB3-4mhzAT A&T, 4 MHz $464.95

SSM-VB3-4mhzUPG 80 x 48 upgrade, 4 MHz .. $ 89.00

T1 Active Terminator

SSM-T1K kit $ 34.00

SSM-T1AT A&T $ 64.00

VB2 I/O Mapped Video Interface

SSM-VB2K kit $160.00

SSM-VB2AT A&T $210.00

XB1 Extender Board

SSM-XB1K kit (with Connector) $ 22.00

SSM-XB1AT Assembled & tested $ 30.00

Z-80 STARTER KIT - SD Systems

2-80 computer with RAM, ROM, I/O & keyboard

SDS-Z80K kit $374.00

SDS-Z80AT A&T $454.00

QT MEMORY EXPANSION KITS

TRS-80» APPLE•EXIDY

4116 200 ns 8 for $32.00

2716 (5V-450 ns) $ 9.00

2716 (5 & 12V-450 ns) $ 9.00

2732 (5V) $40.00

2114L 300 ns 8 for $36.00

100 - $3.50 ea.

.A.

y^z

MICROPROCESSORS

Z80 (2MHz) ... $10.95 Z80A (4MHz) . . $12.95

6502 $11.25

6800 $12.50

6802 $18.00

8035 $20.00

8080A $ 3.50

8085A $20.00

8086-4 $60.00

8088 $60.00

8748 $60.00

TMS 9900 JL . . $29.95

8080A SUPPORT

8212 $ 3.50

8214 $ 4.50

8216 $ 2.95

8224 $ 4.00

8228 $ 6.00

8238 $ 6.00

8243 $ 5.00

8251 $ 7.00

8253 $19.00

8253-5 $20.25

8255 $ 6.25

8257 $17.95

8257-5 $19.00

8259 $19.95

8275 $69.95

8279 $17.50

8279-5 $18.00

8295 $16.50

KEYBOARD CHIPS

AY5-2376 $13.75

AY5-3600 $13.75

BAUD RATE GENERATORS

MC14411 ... $11.00 1.8432 XTAL ...$ 4.95

DISK CONTROLLER

1771B01 $24.95

17B1A01ICER) $37.95

EPROMS

1702A $ 4.95

2708 $ 6.25

2516 (5V) $18.00

2716 (5V) .... $13.50 2716 (5 & 12V) $13.50

2758 $19.95

2532 $55.00

2732 $55.00

USRT S2350 $ 7.95

MISCELLANEOUS OTHER COMPONENTS

N8T20 $ 3.25

N8T26 $ 2.50

N8T97 $ 2.00

N8T98 $ 2.00

1488 $ 1.25

1489 $ 1.25

D3205 $ 3.00

D3242 $14.00

P3404 $ 6.75

TMS5501 $19.00

DM8131 $ 3.00

UARTS

TR1602B $ 4.50

AY5-1013A $ 4.50

CHARACTER GENERATORS

2513 $10.95

UP CASE (5&12V) 2513 $10.95

LWR CASE (5&12V) 2513 $ 9.75

UP CASE (5V) 2513 $10.95

LWR CASE (5V)

6800 PRODUCTS

6802P $18.00

6821P $ 5.25

6840P $18.25

6845P $22.00

6850P $ 4.80

6860P $11.55

6875P $ 7.40

SBC+2/4 SINGLE BOARD COMPUTER

Features: 1K RAM (which can be located at any 1K boundary) plus one each Parallel and Serial I/O parts on board • Power on jump to on-board EPROM (2708 or 2716) • EPROM addressable on any 1K or 2K boundary 'Full 64K use of RAM allowed in shadow mode • Programmable Baud rate selection, 110-9600 • 2 or 4MHz switch selectable • DMA capability allows MWRTsignal generation on CPU board or elsewhere in system under DM A logic or front panel control • Two programmable timers available for use by programs run with the SBC+2/4 (timer output and controls available at parallel I/O connector; parallel input and output ports available for use on CPU board).

Bare Board $ 60.00

Kit $190.00

A&T $295.00

J

Z+80 CPU

Features: Power on jump toon-board EPROM (2708, 2716 or 2732) • EPROM addressed on any 1K or 2K boundary; also shadow mode allows full 64K use of RAM • On-board USART for Synchronous or Asynchronous RS-232 Operation (Serial I/O port) • Programmable Baud rate selection, 110-9600 • Switch selectable 2 or 4 MHz • MWRITE signal generated if used without front panel • Front panel compatible.

Bare Board $ 50.00

Kit $150.00

A&T $210.00

J

CLOCK/CALENDAR+ FOR APPLE II, S-100 OR TRS-80

Features: Date/Month/Year • Day of week • 24 hour time or 12 hour (a.m./p.m.) selectable • Leap year (perpetual calendar) • 4 interval interrupt timer; 1024Hz (approx. 1 millisec), 1 sec, 1 min., 1 hr. • On-board battery backup • Simple time and date setting • Simple software interface • Time advance protection while reading.

S-100 or Apple TRS-80

A&T $150.00 A&T Only ... $150.00

Kit $100.00

Bare Bd $ 60.00

SMART PROTO BOARD+

Features: Wire-wrap or solder sockets • Accepts all std. sockets — .30" & 60" center • Allows grid distributed power • Three voltage regulators • Kluge area for discretes, ext. drives • Two bus bars for ± voltages — int. & ext. • Accepts std. edge connector on .1" center • K it includes 3 regulators/3 heat sinks/ filter capacitors/2 bus bars/Manual.

Bare Board $ 35.00

Kit $ 60.00

QT PRODUCTS

EXPANDABLE+ REV II DYNAMIC MEMORY BOARD

Features: Runs at 4MHz • 3242 refresh controller with delay line • Four layer PC board insures quiet operation • Supports 16K, 32K, 48K or 64K of memory • 24 IEEE-specified address lines • Optional M1 wait state allows error free operation with faster processors • Optional Phantom disable • Uses Z-80 or onboard refresh signal • Bank on/off signal selected by industry standard I/O port 40 (Hex) • Convenient DIP switch selection of data bus bits determines bank in use • 3 watts low power consumption • Convenient LED indication of bank in use.

Definitely works with Cromemco and North Star.

Bare Board $ 75.00

KIT A&T

No RAM .... $230.00 16K $350.00

16K $280.00 32K $450.00

32K $360.00 48K $575.00

48K $480.00 64K $675.00

64K $525.00

RAM+16

Features: S-100,16Kx8 bitstatic RAM • 2or4 MHz* Uses 2114 1K x 4 static RAM chip* 4K step addressable • 1K increment memory protection, from bottom board address up or top down • Deactivates up to six 1K board segments to create "holes" for other devices • DIP switch selectable wait states • Phantom line DIP switch • Eight bank select lines expandable to Vi million byte system • Data, address and control lines all input buffered • Ignores I/O commands at board address.

Bare Board $ 35.00

4Mhz Kit $180.00

4Mhz A&T $210.00

WATCH FOR THE FOLLOWING NEW BDS:

• 4 Port Serial Bd (FEB)

• E-PROM Programmer (MAR)

• Floppy bisk Controller (APR)

• Hard Disk Controller (MAY)

• Color Video Bd (JUN)

V

I/0+ INDUSTRIAL GRADE I/O BD

Has two serial Sync/Async ports (RS-232, current loop or TTL) with individual Xtal controlled programmable baudrate generators • Four 8-bit Parallel ports; one latched input port and otherthree can be programmed in combinations of input, output or bidirectional • Also, has three 16-bit Programmable Timers and an 8-level Programmable Interrupt Controller w/Auto restart (8080/ Z80) • Other features include; on-board clock divisor for timers, completely socketed, wire wrap posts for easy port configuration plus more.

Bare Board $ 70.00

Kit $200.00

A&T $375.00

SILENCE+ MOTHERBOARDS

These motherboards are among the quietest on the market. A unique grounding matrix — with each line completely surrounded by ground shielding — eliminates need for termination and gives high crosstalk rejection • They're customer-proven, without crosstalk sometimes operating at 14MHz • A LED power indicator helps eliminate zapped circuits • IEEE S-100 std. compatible, available with 6, 8, 12,18 or 22 slots • (The 22 slot board fits Imsai chassis and has slot for front panel.)

6 Slot

Bare Board $ 25.00

Kit $ 40.00

A&T $ 50.00

8 Slot

Bare Board $ 27.00

Kit $ 55.00

A&T $ 70.00

12 Slot

Bare Board $ 30.00

Kit $ 70.00

A&T $ 90.00

18 Slot

Bare Board $ 50.00

Kit $100.00

A&T $140.00

r QT MAINFRAMES . }

57." Disk Mainframe with 18A Pw MF+MD12 (12 slot M/B)

r Sup $500.00 $450.00 $400.00

$450.00 $500.00 $600.00

MF+MD6 (6 slot M/B)

MF+MD w/0 M/B

QT. Mainframe MF+12 (12 slot M/B)

MF+18 (18 slot M/B)

I MF+22 (22 slot M/B)

MAINFRAME+ DISK DRIVE

Includes cabinet, 30 amp power supply, IEEE S-100 compatible 6, 8 or 12 slot motherboard and dual 8" disk drive with disk drive power supply.

MF+DD6 $625.00

MF+DD8 $650.00

MF+DD12 $675.00

DDC-8 SINGLE 8" DISK CABINET

Accepts one 8" disk drive (Shugart, Remex, PerSci, Siemens, etc.) • Fan cooled, with data cable and AC line filter to eliminate EMI • Operates from 100-125 VAC/200-250VAC at 50-60HZ • Disk drive NOT included. DDC+8 $175.00

COMPUTER SYSTEMS INC.

15620 South Inglewood Avenue Lawndale, California 90260 (2U) 970-0952

PLACE ORDERS TOLL FREE

1-800-421-5150

(CONTINENTAL U.S. ONLY)

(EXCEPT CALIFORNIA)

Apple is a trademark of Apple Computer, Inc. CP/M and MP/M are trademarks ol Digital Research. TRS-80 is a trademark of Radio Shack.

Circle 329 on inquiry card.

TERMS OF SALE: Cash, checks, money orders, credit cards accepted. Also C.O.D. orders under $100.00. Minimum order $10.00. California residents add 6% sales tax. Minimum shipping and handling charge $3.00. Prices subject to change without notice. International sales in American dollars only. .^^_

VISA

l^^g

SALE SALE SALE

Disk Drives

JADE's new dual disk sub-assemblies include: Handsome metal cabinet with proportionally balanced air flow system, rugged dual drive power supply, cooling fan. cable kit, lighted power switch, approved fuse assembly, line cord. Never* Mar rubber feet, and all necessary hardware to mount 2-8" disk drives ■ it's all American made, guaranteed for six months, and it's in stock! Dual 8" Sub-Assembly Cabinet

END-000421 Cabinet kit $225.00

END-000420 Bare cabinet $59.95

Single sided, double density disk drive sub-system END-000423 Kit w/2 8" drives .... $975.00 END-000424 A & T w/2 8" drives $1195.00

Double sided, double density disk drive subsystem END-000426 kit w/2 8" drives .... $1495.00 END-000427 A & T w/2 8" drives $1695.00

JADE DISK PACKAGE

Double density controller, two 8" double density floppy disk drives, CP/M2,2 (confiffured for controller), hardware and software manuals, boot PROM, cabinet, power supply, fan, & cables Special package price $1395.00

8" Disk Drive Sale

Highly reliable double density floppy disk drives Shutfart 801 R single sided, double density

MSF-10801R SA-801R $425.00

Special Sale Price 2 for $790.00

Siemens FDDlOO-BDIi single sided, double density

MSF-201120 f, mo warranty $385.00

Special sale price 2 for $750.00

Real Double-Sided Drives

8" Double-Sided Double-Density Sale

* Shugart SA-H51R double-Hided, double-density *

* only $625.00 ca 2 for $1100.00 *

MFE M701 8" double-sided, double-density driues only $526 ea 2 for $1040.00

Qume Data Track 8 double-sided, double-density drives only $575.00 2 for $1100.00

Printers

~ CENTRONICS 737^1

.9 x N dot matrix, letter quality, proportional spacing

PRM-15737 Parallel $795.00

With interface for Apple $895.00

MX-80 - Epson

1112 column, II x 9 dot matrix, multiple fonts

PRM-27080 Save $100.00 $545.00

Interface for Apple $110.00

SPINWRITER- NEC

ti5 cps. bi-directional, letter quality printer with deluxe

tractor mechanism, both parallel and serial interfaces on

board, 16K buffer, ribbon, print thimble, graphics, micro

space justification, data cable, and self test/diagnostic

ROM.

PRD-55511 without WK buffer ... $2795.00

PRD-55512 with 16K buffer $2895.00

S-100 Systems

S-100 SYSTEM - Calif Computer Sys

Complete S-100 system including 12 slot mainframe. 4 MHz Z-80 CPU. S4K RAM memory, double density disk controller. RS-2.12 cable. 8" & 5W'disk drive cables. Cl'/M 2.2, manuals, auto boot ROM. completely assembled & tested.

2210A Integrated & tested $1995.00

2210B Not integrated $1795.00

S-100 Memory

64K RAM - Calif Computer Sys

4 MHz bank port / bank byte selectable, extended addressing. ItiK hank selectable. PHANTOM line allows memory overlay, 8(18(1 / Z-80 / front panel compatible. MEM-64565A A & T $449.95

MEMORY BANK -Jade

; Mil;. IKKK S-IOtl, hunk selectable. 8 or Iti bit

MKM-99730B Bur,' hoard $55.00

M KM-99730K Kit. no NAM $219.95

MKM-1073OK WK kit $2 19.95

M KM-3273 1 K H2K hit $289.95

MKM-48732K -IHK hit $324.95

MKM-0I733K (UK kit $359.95

Assembled & tested add $50.00

EXFANDORAM II - S I) Systems

/ Mlh RAM hoard expandable from WK to ■JtfKK

MKM- 1 6630K ItiK kit $275.95

MKM-32631 K :i2K Id! $295.95

M KM-I8632K -IKK kit $315.95

MKM-HHJ.I3K (iIK kit $335.95

Assembled & tested add $50.00

32K STATIC RAM - Jade

:>. or I Mlh expanilahle static RAM board tttte.i :U I II.'s

MKM-I(> 151K /(IK I MHz kit $ 109.95

MKM-32 1 5 1 K -I2K I MHz kit $299.95

Assetlihiecl & tested add $50.00

16K STATIC RAM - Cal Comp Sys

2 or 4 MHz IKK static RAM board, IEEE S-lilt), bank selectable. Phantom capability, addressable in 4K blinks MEM-16160A 1SK 2 MHz A & T ... $286.95 MEM-16162A 1GK 4 MHz A & T ... $289.95 MEM-16160B Bare board $50.00

PB-1 -S.S.M.

271)8. 2710 HPROM board with built-in programmer

MEM-99510K Kit $154.95

MEM-99510A A&T $229.95

PROM-100 - SD Systems

271)8. 27lti. 27112. 2758. & 2,5/6 EPROM programmer

MEM-99520K Kit $219.95

MEM-99520A Jade A & T $269.95

S-100 Video

VB-3 - S.S.M.

HO characters x 24 liiws expandable toHO.x 48 for a full pay.e of text, upper & lower case,2,'~)6 user defined symbols, HiOx 192 f.raphics matrix, memory mapped, has hey board input.

IOV-1095K 4 MHz kit $375.00

IOV-1095A 4 MHz A&T $450.00

IOV-1096K 80 x 48 upgrade $39.95

VIDEO BOARD -Jade

64 characters x 16 lines, 7 x ,9 dot matrix.f till upper/lower case ASCII character set, numbers, symbols, and t>reek tetters, normal/reverse/blinking video, S-100.

IOV-1050K Kit $99.95

IOV-1050A A&T $125.00

IOV-1050B Bare board $19.95

S-100 CPU

2810 Z-80* CPU - Cal Comp Sys

2 -I MHz Z-80A* CPUmi 111 RS-232C serial I Oport and onboard MOSS 2.2 monitor PROM. front panel compatible. CPU-30400A A&T $269.95

THE BIG Z* - Jade

2 or 4 MHz su-itcltablc Z-80* CPU with serial I/O. accomodates 2708. 2716. or27.!2 EPROM. baud rates from

7r> to Willi)

CPU-30201K Kit $145.00

CPU-30201A A&T $199.00

CPU-30200B Bare board $35.00

CB-2 Z-80 CPU - S.S.M.

2or 4 MHz Z-8II CPU board with provision foruptoHKaf ROM or -IK of RAM on board, extended addressing. IEEE S 11)0. front panel compatible. CPU-30300A A & T $229.95

SBC-200 - SD Systems

■/ MHz Z-80* CPU with serial & parallel I/O ports, up to8K of onboard PROM, software programmable baud rate generator. IK of onboard RAM. Z-8II CTC.

CPC-30200K Kit $339.95

CPC-30200A Jade A&T $399.95

S-100 Disk Controller

DOUBLE DENSITY - Cal Comp Sys

h'/i" and 8" disk controller, single or double density, with onboard boot loader ROM. and free CP/M 2.2* and manual set. IOD-1300A A&T $369.95

DOUBLE-D -Jade

Bon hie density controller with the insi d e track.on-boar d Z8I1A*. printer port. IEEE S-ttlt). can function on an interrupt driven buss

IOD-1200K Kit $299.95

IOD-1200A 8" A & T $389.95

1OD-1205A 5>/t" A & T $389.95

IOD-1200B Bare board $65.00

VERSAFLOPPY II - SD Systems

New double density controller for both 8" & 5'/i"

IOD-1160K Kit $379.95

IOD-1160A Jade A & T $439.95

Motherboards

ISO-BUS - Jade

Silent, simple, and on sale ■ a better motherboard

6 Slot (51/." x 8'A")

MBS-061B Bare board $19.95

MBS-061K Kit $39.95

MBS-061A A&T $49.95

12 Slot (•>'/," x 8-Vx")

MBS-121B Bare board $29.95

M BS-121 K Kit $69.95

MBS-121A A&T $89.95

18 Slot (H1/." x 8V«")

MBS-181B Bare board $49.95

MBS-181K Kit $99.95

MBS-181A A&T $139.95

Card Cages

S-100 CARD CAGE - Jade

Metal cage with card guides & fan mntintin/.'.

KNX- 1 0600 I Six slot $29.95

S-100 CARD CAGE - Vector

HI" ruck iiinlinlolilr. adjustable, holds :>.! curds

VCT-C'CK 1 00 Armdizvd Al $49.95

SALE SALE SALE

S-100 I/O

S.P.I.C. -Jade

Our new I/O card with 2 SIO's, 4 CTC's. and 1 PIO IOI-1045K 2 CTC's, 1 SIO, 1 PIO .. $199.00

IOI-1045A A & T $259.00

IOI-1046K 4 CTC's, 2 SIO's, 1 PIO $259.00

IOI-1046A A & T $319.00

IO1-1045B Bare board w/ manual ...$59.95 1OI-1045D Manual only $20.00

1/0-4 - S.S.M.

2 serial IIO parts plus 2 parallel I/O parts

IOr-1010K Kit $179.95

IOI-1010A A &T $249.95

1OI-1010B Bare board $35.00

TERMINATOR - S.S.M. Active terminator far S-100 has

TSX-195K Kit $29.95

TSX-195A A & T $54.95

TSX-195B Bare board $22.95

S-100 EXTENDER - Cal Comp Sys

Put those problem hoards (the ones you probably bought from one of our competitors) within easy reach. TSX-160A A & T $37.95

S-100 PROTO BOARD - Jade

Universal design, plated thru hales, gold fingers TSX-140B Bare board $24.95

TERMINATOR & EXTENDER - CCS.

Can he used as hath an S-100 extender and terminator TSX-150K Kit $43.95

Diskettes

DISKETTES - Jade

Bargain prices an magnificent magnetic media rr/\" single sided, single density, box of 10

MMD-5110103 Soft sector $27.95

MMD-5111003 10 sector $27.95

MMD-5111603 16 sector $27.95

5'/i" double sided, double density, box of 10

MMD-5220103 Soft sector $39.95

8" single sided, single density, box of 10

MMD-8110103 Soft sector $33.95

8" single sided, double density, box of 10

MMD-8120103 Soft sector $39.95

8" double sided, double density, box of 10

MMD-8220103 Soft sector $49.95

Video Monitors

9" B & W MONITOR - A.P.F.

High quality, high resolution video monitor VDM-750900 9" monitor $159.95

13" COLOR MONITOR - Zenith

The hi res color you've been promising yourself VDC-201301 $449.00

12" GREEN SCREEN - NEC

20 MHz. P.'il phosphor video monitor with audio, exceptionally high resolution ■ A fantastic monitor at a very reasonable price VDM-651200 12" monitor $259.95

Mainframes

MAINFRAME - Cal Comp Sys

I2slat SIOO mainframe with 20 amp power supply

ENC-112105 Kit $359.95

ENC-112106 A & T $419.95

DISK MAINFRAME - NNC

Holds 2 8" drives and an 8 slot SIOO system. Attractive metal cabinet with 8 slat mallierboard, powcr supply, f an, key switch, and other professional features ENS-112320 with 30 amp p.s $699.95

Accessories-Apple/TRS-80

16K MEMORY UPGRADE

Add UiKaf RAM to your TltS-80. Apple, or Exidy in just minutes. We've sold thousands of these 10K RAM upgrades which include t he appropriate memory chips (as specified by the manufacturer), all necessary jumper blocks, foolproof instructions, and our 1 year guarantee.

MEX-16100K TRS-HO kit $29.00

MEX-16101K Apple kit $29.00

M EX-16102K Exidy kit $29.00

DISK DRIVE for APPLE

o'/i" dish drive with controller for your Apple

MSM-12310C with controller $499.95

MSM-123101 wlout controller $375.00

DISK DRIVES forTRS-80

23% more storage, 8 times faster, 40 track with free patch. 120 day warranty, includes case,power supply, and cable MSM-12410C Saue $125.00 .'.'.' $299.95

DOS 3.3 UPGRADE - Apple

Upgrade your old DOS to t he improved ,'1.,'f IOD-2233A Complete kit $64.95

APPLE STICK - Micromate

Joy slick with puts for Apple II SYA-1510A A &T $35.95

Z-80* CARD for APPLE

Z-SO* CPU card with CP/M2.2 for your Apple CPX-30800A A & T $279.95

AIO -S.S.M.

Parallel & serial interface for your Apple

1O1-2050K Kit $155.95

IO1-2050A A & T $194.95

PRINTER INTERFACE - CCS.

Centronics type 1/Ocard w/ firmware IOI-2041A A & T $99.95

APPLE CLOCK - Cal Comp Sys

Real time clock le battery back-up 1OK-2100A A & T $109.95

Modems

•••••••••••••••••••••••••

LEX-ll MODEM - Lexicon

A rval star! :W(I baud, answer/originate, US 'JI12C

IOM-5511A Best buy .'.'.' $128.00

•••••••••••••••••••••••••

NOVATION CAT

300 baud, answer/originate acoustic modem IOM-5200A I year warranty $179.00

D-CAT 1100 baud, direct connect modem IOM-5201A Special sale price $189.00

AUTO-CAT Auto answer origiate. direct connect IOM-5230A Special sale price $239.95

MICROMODEM - D.C Hayes

Aula answer dial modem card for Apple or SIOO

IOM-2010A Apple modem $349.95

IOM-1100A S-100 modem $375.00

MICRONET MODEM - Micromate

Direct connect with extra features - a best buy IOM-2020A Best Apple modem $275.00

* Z-80. Z-80A, and the letter Z are recognized trademarks of Zilog, Inc. *C1VM is a registered trademark of Digital Research Corp. "CBASIC is a trademark of Compiler Systems, Inc.

Circle 330 on Inquiry card.

Single Board Computers

AIM-65 - Rockwell

(J502 computer with alphanumeric display, printer, & keyboard, and complete instructional manuals

CPK-50165 IK AIM $374.95

CPK-50465 4K AIM $449.95

SFK-74600008E SK BASIC ROM ...$99.95 SFK-64600004E 4K assembler ROM $84.95

PSX-030A Power supply $64.95

E NX-000002 Enclosure $49.95

-IK AIM. UK BASIC, power supply. & enclosure Special package price $625.00

Z-80* STARTER KIT - SD Systems

Complete Z-80* computer with RAM. ROM. I/O, display.

keyboard, manual, and kluge area.

CPS-30010K

CPS-30010A J

ade A & T $459.95

MICROPROCESS

OILS

10.95 12.95 1 1.50 11.95 17.95 :19.95 2-1.00 6.59 15.95 59.95

r

9.50 1 1.50

9.50 1-1.95 211.50

I'ROMS

2708 -1311ns

Ill for St.90 em 2716 ISLIu

. 6.25

6302

11.95 11.95

10 for- S8.90 <M

25;a 5v

0809

39.95

2732 &•

39.95

2758 ;>!' . .

8U85

87-18

RAMS 21UI2 2 MHz

. 1.25

:1881 PIO

211j02A / MHi

. 1.50

:l881-4 PIO1 MHz

3882-1 CIV I Mill. iWcVA SIO

. 4.25

4161 frlK xl

5257 2 Mllz

5257A I MHz ....

59.95 . 6.75

3 l(UK) . 1.95

5.25 8.25 . 5.25 5.95 9.00

. 7.25

MK1H8 . .

MAUD UATK CKNKKATOK MC1441I

SUPPORT DKVICKS

1.84:1 Mllz xtal ...

UARTS

8214

.. 4.65

AY5-101.1A

8216

.. 2.95

AY3-1014A

TK1602B

TMS601I

8224-4

8226

8228

8S18

. 5.75

4 95 4.95

SWH)

SUPPORT

8250

8251

14.95

11.95

22.50

18.75

1.80

5.79

7.40

«S 00

(S828P

8:25:1 ....

8255

8257

8275

8279

68188 P

PLACE ORDERS TOLL FREE

Continental U.S.

800-421-5500

Inside California

800-262-1710

For Technical Inquiries or Customer Service call

213-973-7707

Computer Products

4901 W. Rosecrans, Hawthorne, Ca 90250

TERMS OF SALE: Cash, checks, credit curds, or I I'lirchn.st Orders from qualified firms and institutions. ■ Minimum order $15,00. California residents add fi}U tax. ■ Minimum shipping and handling charge IfcUJO Pricing = and availability subject to change without notice.

CaMFornja DiqiTAl

Post Office Box 3097 B • Torrance, California 90503

FREE PLASTIC LIBRARY CASE INCLUDED WITH THE PURCHASE OF EVERY BOX OF DISKETTES

labeled lor California Digital by one of ii respected prot.'uccrs ol magnetic medi skeite la certified double density at -10 To insure extended media life each dis

MMD-CDS(OUIlO)

2495

(■ I. BOX

Ten boxes $22.75

MINIDISKETTES

One hundred boxes $21.50

Scotch 74-)IO)llO)(lG} 831.

EIGHT INCH Scotch

box 10 bx

Dysan box 10 bx. .MUX box 10 bx

Single side/slui;le den. 740-0

535. $33.

3740/1 S49. S47. 3060 S-.S. $-:3,

Single aide/dim bio den. 741-0

45. 43.

Single side/33 suet or 740-32

35. 33.

Double side/ double D. 743-0

65. 59.

na. 3115 49. 45.

SCOTCH brand head cleaning k

It. $24.85

i\IMA-CK{5)(8> please specify 5 1/4 8"

PrlceB available on request for

: tape, cart

ridges, diskpacks, volumn diskettes.

MEMORY

TRS-80 • APPLE II

16k memory (8) 4116's

Installation is simple. Anyone who has ever changed a spark plug should be able <. to up-grade his microcomputer. How can California Digital offer these memory up-grade sets at 25% below our competition? Simple, we buy in volume, wholesale to dealers and sell the balance directly to owners of personal microsystems. These 16K dynamic memory circuits are factory prime and unconditionally guaranteed for one full year, NOW, before you change your mind, pick up the telephone and order your up-grade memory from California Digital. Add S3 for TRS80 jumpers.

1K+

4.75 4.50

STATIC

1

31

32

-99

100-5C

21L02 450nS.

1

19

99

21L02 250nS.

1

49

1

39

2114 1KX4 450

5

95

5

50

5

25

2114 1KX4 300

8

95

8

50

a

00

4044 4tetl 450

5

95

5

5 0

5

25

4044 4Kxl 250

9

95

9

50

9

00

4045 1Kx4 450

B

95

8

50

8

00

4045 1KX4 250

9

95

9

50

9

00

5257 lowpow.

5

95

5

50

5

00

2716 EPRQM

We have slashed price in an effort to reduce our over stocked inventory. These are single five volt EPROMs manufactured by one of the Worlds largest producers | of semiconductors. All are first quality prime devices. Ceramic 450 nS.

UItr/vVioIet PnoducTs UVS11-E

UV EPR0M ERASER

With purchase of FORTY

2716 EPROM's

*//rvalue

Jra'1

NEW

from

Shugart Technology

SURPL

Megabyte Hard Disk Drive

Packaged in the same physical size as the industry standard 5 1/4" minifloppy disk drive. The micro-Winchester stores thirty times as much data (6.38 megabytes unformatted), accesses data twice as fast (170 milliseconds) and transfers data twenty times faster (5.0 megabits per second. )

The ST506 is factory sealed to protect the media from environmental contaminates. Requires only DC voltage. Dual California Digital 5 1/4" enclosure, ST506 drive and power supply.

Shugart Associates SA400 removable media disk drive for above package, add: S-100 & Apple controller scheduled for spring release.

H500 *300

%/5-Sh

ugart Associates

801/ R Disk Drive

Shugart B01/H with CP 206 po\

15 lbs

supply, muffin cxtinu piete in aual enclosure witn au tne necessary harness! Documentation included. 30 pounds. M5D- 1801 Same as above but with two Shugart B01R disk di-lvcn. 50 pounds. MSD-2H01

Disk drive cable. G feet 50 conductor with edno card c at both ends. WCA-G50S $25.00 ExpoctJ^isk drives. 220V. 50Mlli add S50.00 per disk drlvi

♦795 U195

The new BSR timer runs your home jus

like clockwork. Turn*

on lamps and

appliances while your awav from home.

Completely compatible

istlng System X-10 devices.

HSR Timer eight channel 565.00

Appliance Module 5

0 W. SI3.95

Master control console 34.95

Lamp Module 300 V

Ultrasonic Controller 19.D5

NEW full control wa

1 switch 14.50

Rotron Wisper Fan *1477

115 VAC. 7 Watts WB2A1 Factory fresh Muffin fans NOT pull-outs, EMF-4M

ONHECTOIiS

mumma*

El

22°

GOLD KUC.l. CUNM ClOKS

•«*«rrap IT™*

l-Rel. .isr i-Rel. WAV

.156" Centers (standard)

22/44 KJn. Eyelet 2.50 2.:

36/72 Digital Croup S/T S.B5 5.;

36/72 Digital Croup W/W S.60 6.:

■13/86 Motorola G80D5/T 6.60 6.:

43/86 Kioto.6800 WAV 7.00 6.!

LNTECK.1TED CIRCUIT SOCKETS

1.50 1.35

I),mS female JJA hood 2/r" JJB2SP male UBZSS female

DUSOF mole 5.5 DL150S female 9.4 UDaOhood 2/P2.6

3.10 2.50

RIBBON CABLE CONNECTORS

17/34 5" disk 4.85 4.15 3.S5 20/40 TRS-80 5.65 5.05 4.70 25/50 B" disk 5.90 5.15 4.90

VISA

mmmmmm

. merchandise sold by California Digital is premium grade, inds $2.00; each additional add $.40 ipping. Excess will be refunded, lifornia residents add 6% sales tax. COD's discouraged, "in accounts extended to state supported educational institus and companies with a "Strong Dun & Bradstreet. "

it.

Split

3

18v-^ S-IOO

POWER

^-" 22V. ct % 24V disk

£Z15Vf 15V.

f~Fan

upable of supporting ; and T»Q I2.000/J0\;

SUPPLY KIT

$

59

tifiers five computer Er; Im.irv transformer UlO/2 1 30 Amp S-10O system al

ach Bi.000 UF/15V-. 3-5.00'

□ATA INPUT TERMINAL

CMC division of Hie Pert as originally deslgnt gnetfe tape.

PORTABLE DATA ENTRY SYSTEM

lll'-Sf

sed data terminals were originally designed for retail store order en! terns. The operator enters tfas Inventory control number, merchandise 01 d and the unit price. After all pertinent data has been entered, the main v se is telephoned. Hie handset Is placed in the acoustic coupler an all the n ded Information is transmitted back the master computer. :h system includes: Casselte drive unit: Removable hex keyboard with LED I display; Five Gould "D"N"iCads with charger; AcoustLcal coupler and DB25 cab ed from service In working condition. Original cost over S2.51

Regulated

Power Supply

5volt5amp

$1195

This USED surplus power Ripply was removed Pass transistor regulation outputs five volts at ; Suitable for TTL hubby applications. SPC-PS1

■oni working ■ ■ j :i;i:

J59 Sankyo Magnetic Card Transport

a single 2x4" HP style mapic-tle date card. Motorized mech:mi;mi pulll tin: magnetic card across the four channel road/writ head in under two seconds. Ideal for any data processing application where sin; amounis of information must be randomly retrieved. Original cos*, over $200.(H Documentation and sample card included. Ne<

WESTERN UNION

ENCLOSURE

vernal Technology. The exacl purpose of the product is still a mys:rrv but ;r;e enclosure Is ieoiily sjited for an S-100 molhc board with shielded power supply Removable hood and plexlglaa front make this enclosure an attractive home for any hobby prothi' New surplus in factory boxes s: 22/44 edge connectors; DB 25S

101/

TOLL FREE ORDER LINE

800)421-5041

TECHNICAL & CALIFORNIA

213679-9001

CaMForni'a DiqiTAl

Post Off if 3 Box 3097 B • Torrance, California 90503

MEMOREX MEMOREX 1 ^ MEMOREX -MEMOREX

SUPER BUY

IBM direct price '1295

CALIFORNIA DIGITAL

discount price

$11OC immediate

IKK) deliver

j5cftpdaaaiaQQDQ|

NEW

from INTEGRAL DATA

Paper Tiger

GRAPHICS '1150

NjE"C Spin writer 551QP/I

*279

The word processing quality Spii.wrili.-r prints at speeds uplo Sj char aclers per second. The Model 3510 I'/S is supplied with bolh parallel and HS-232 serial Inter faciei k- Also included is (he tractor teed mec anism. along With prim t him tile ,lid riiibola. I'ilN-a.iiepS TO lbs.

Keyboard <KSil) Model 5520 P/S available 3299',. PRN-5520 PS 75 lbs.

JEC V-300

®Word Processing

DaisyWheel Printer

*1595

Finally a 25 cliara. 1/120" lit

d Diablo brand (nterchangal 1 8085 CPU microprocessor conlroil nector. Shipping 58 lbs. PRV-300.

TELETYPE MODEL 43

4320 KEYBOARD MODELS

TTL serial output AAA $ 995

RS232 serial AAK 1050

Friction 80 column AAE 1100

Friction 80 RS232 AAL 1195

Bell 103 Modem AAB 1495

nsr

EPSON

MX-80 *495

The MX-tlO idiSvll 110 char:t second dot matrix printer, feed n:uch;inism adjusts to accept Ven . ..or. Requires.' Eight bit" arallel interfacing I'RE-.MXSi 17 Lb.

CEnTRonics 730 $595 737 $750

Botli the Centronics 730 and the 73? are cap: standard office letterhead or pin feed contfni.

matrix print liead. Parallel interfacing. Add S65 RS232. PRC-730P (S). PRC-737P (S) 17 lbs.

HEWLETT PACKARD

2650

HP

plete. low cost portable con-.pi system. This self contained p includes CPU. keyboard, prin Cltr display ;ind cassette (ape SVS-lll'S;. 30 lis.

26 Megabyte Hard Disk Drive

from

George Morrows

Thinker Toys

$

omruller £343

AMPEX

DIALOGUE 80 CRT TERMINAL

s995

BMC

VI MONITOR

$259

mposil video input make the EMC

, tit..'' resolution 12' display. nipact pljstic enclosure assures that llii> UMC monitor is a rugged nvwhere instrument. lor added p rs-ii.-eiic.il the unit Is ftuiLppt:d with o'vable st.iokednod-cl.ire n lexU'lns icrtvn. VP.M-BMC III lbs.

direct connect

MODEM

Direct cinnucl modems elimL-latt: loss of inf orma-.ioi associated with acoustic modems. Choose cither oft

The Universal Data Systems I03L.P is snitch selects Inate modes, Fully Bell 10:1 compatible. Directly c

prosimity 10 A.C.iiowur reoupUclc. MOU-103L11

Your Choice

*169

V/SA

t of ihs new "Heir modular handsets, ideal f.

All merchandise sold by California Digital is premium grade.. Shipping: First five pounds $2.00; each additional add $.40 Foreign orders 10% shipping. Excess will be refunded. California residents add 6% sales tax. COD's discouraged.'' Open accounts extended to state supported educational institutions and companies with a "Strong Dun & Bradstrect. " Warehouse: 15608 Inglewood Blvd. Visitors by appointment.

Circle 321 on.inquiry card.

ACCESSORIES FOR THE

COMPUTER

CALIFORNIA COMPUTElt SVSTEMS Arithmetic Processor 7811 B/C S31

12 K PROM Calendcr/C Parallel Int Profii

lat. back-up 742-t lei Interface 7720A ■amablc Timer 7740A g/Digital converter T-170A

MICROSOFT PRODUCTS Apple to 2-80 CPU card D.C. H.AYF.S PRODUCTS IMiciomodem for Apple COMPUTER STOP PRODUCTS Double Vision / BO Column Video INTERACTIVE STRUCTURES IB Channel A/D card A10/2

MOUNTAEi COMPUTER PRODUC

Intro X-10 system for BSR

Intro X-10 card otflv

16 channel AD/DA B bit

Apple Clock battery back-up

Sipertalker SD200

ROW Plus with filter

ROM Wrilor/Prograr.imer

APPLE BRAND PRODUCTS

Apple Language card

Floppy disk with controller

r\pple pai

lei t

SSM MJCROCOMPUTE

S-IOO BOARDS

Assembled • Tested • Burned in

GODBOUT/COMPUPRO Dual 8088/8085 16 bit CPU Z-SO CPU 2

licit A

1 32K (Alpha MiC :olor graphics be

Spectrum color gra Intcrfacer 11 I/O c SEATTLE COMPUTER PRODUCTS 80B6 16 bit CPU 2 card set/88 dos S9S CALIFORNIA COMPUTER SYSTEMS S-100 Mainframe 22O0A 329

Disk controller/2. 2 CPM 2-122 329

Z-80 CPU 4MFIzD;i1A 2810A 250

DIGITAL RESEARCH

32K 2716 EPROMboard 99

EPROMS for above 2716 16 rcq. 13 CALIFORNIA DATA CORPORATION A/D board 16 channel 12 bits QT COMPUTER SVSTEMS

MORROW/ THINKER TOYS Multiboard "HEW" Daisy wheel p real time clock, power on jump, program interrupt cont'l 3P/3S Switchboard Interface -1P/2S Disk Jockey I disk controller Disk Jockey II double density SD SALES PROM-100 programmer

MULLEN PRODUCTS Extender board/Logic probe I Relay Opto/control board D.C. HAYES PRODUCTS Mlcromodem S-100 FCC reo AIITEC ELECTRONICS Wire Wrap prolo board WW/1 General Purpose proto GP /1< CALCFORNIA DIGITAL 8086 CPU 4K on board static

TELETEK

SINGLE BOARD COMPUTER FLOPPY DISK CONTROLLER

The l'DC-1 features the 2-80 CPU along .Vith the NEC 765 lloppy disk controller. The boartl suppor-.a both Singh; or double densltv :. 1/4 or 0" dish drives. Two serial <-l3-»600ud) ami iwo parallel |>Oi'tS add to the flexibility of this single board computer.

anil potential for conlrolliiie a Winchester li.inl disk tlri liltion of an EXUTIKtl ^"' volt power Supply lie Telctek mus capable otprogramini; 2716 t;p»tUlS.

7:.:." -;

:;$695

S-100 Mother Board $35

Quiet Suss

8803-18 18 slot IMSAI

TOLL FREE ORDER LINE

(800)421-5041

TECHNICAL & CALIFORNIA

(213)679-9001

IMAGINE THE 8 INCH FLOPPY

315K BYTES PER SIDE ON 5 1/4" OF COURSE! Micropolis, the worlds largest manufacturer of high density 51/4" disk drives, has been doing it for years. And reliably at that! I II

An ordinary 5 1/4" floppy provides, just 35/tracks per side.. and stores only 70K bytes. This is not nearly enough for anything useful, so instead, Micropolis uses 77 tracks per side. Each track is then formatted with 16 sectors (hard) at 256bytes per sector yielding an impressive 315K bytes per side.

Micropolis drives have a larger capacity than many 8" disk drives, though it only occupies the space of a 5 1/4" floppy. The 315K byte capacity is roughly 4 times the capacity ol a standard 5 1/4" drive. This is what we call QUAD DENSITY.

To achieve the high density capability, you may think Mcropolis had to sacrifice speed or reliability. NOT SO! The track to track access time is only 30us with a high speed data transfer rate of 250,000 bits per second.

By creating this high density format, Micropolis is able to keep your initial subsystem costs to a minimum. Your cost is less than S.002 per byte. Thais a BIG VALUE in a small package.

MICROPOLIS disk subsystems are expandable to keep up with your ever increasing needs. Up to four drives/heads may be daisy-chained on one S400 controller board With all four drives/heads in operation, you have access to over 1.2 MEGABYTES ol on-line storage.

WITH MICROPOLIS, complete means COMPLETE. Each subsystem comes complete with controller interlace, cable, and software. The software includes the MDOS operating system, extended basic, assembler and editor. Everything you need to get "On Line" in one complete package,

MCROPOLIS provides total integration which means they control everything from beginning to end, The result is a better drive lor you, backed by a full 120 day factory guarantee,

Anyone can cut price by cutting out capacity or valuable features: But there'smo-long term advantage in it. Not for the user, Or-the builder. „**"!-' 7~." . ~"~L

"MICROPOLIS takes" a better approach, even though it's harder, using advanced design to provide more capability while alsclowering cost. - -•-

For example, most 51/4-inch floppy disks cut costs by using a cheap, less accurate plastic cam or cam follower to position the read/write head. Most 8-inch floppy disks use a better approach, with a rolled steel lead'screw for this function.

We go them one better and use an all-steel system, with a precision-ground steel lead screw and steel follower. It costs more but gives us greater storage capacity with lower cost per thousand bytes. Not so incidentally, our steel construction (compared to plastic) significantly increases reliability, too. There's even a built-in File Protect feature that prevents accidental loss of valuable data. (A file protected diskette cannot be written on.)

Heat can cause numerous read and write errors that can become hazardous to your data. The major heat producing power supply components are mounted to a large heat sink, external to the cabinet by the power switch and fuse (located at the rear of the cabinet). This design is to assure that the drive components are kept as cool as possible to assure reliable data recovery.

MICROPOLIS has a reputation lor getting along with most everybody, Compatability is not a problem with MICROPOLIS. Their disk drives and/or subsystems can be easily integrated into systems such as Polymorphic, Cromemco, CCS, Ithica Intersystems, Godbout. Northstar, Jade Big Z, QT SBC 2/4, and many others. Many OEM manufacturers rely on MICROPOLIS to get the job done efficiently. Companies like Commodore, Exidy. Harris, and Vector Graphics to name just a lew. Years from now, you can look back with a secure feeling knowing you made the best choice, MICROPOLIS. '•

CAPACITY OF AN IN 5 1/4" FORMAT

THIS

/Vt#C"'/<C'?l*C Jl.l*i

NOT THIS

minim, ,

Because of our incredible purchasing power, PRIORITY ONE ELECTRONICS is able to buy MICROPOLIS disk drives by the thousands and receive special pricing. That special pricing we receive is passed on to you in the form of tremendously discounted prices. Now all that remains is for you to take advantage of this truly incredible buy.

DESCRIPTION

S-100 SUBSYSTEMS

MCP MCP MCP MCP MCP MCP

■1053-4 ■1053-2 ■1043-2 ■1041-2 •1042-1 ■1041-1

1.2 MB 2 HEAD DUAL

630 KB DUAL

315 KB SINGLE

315 KB SINGLE, NO PS

143 KB SINGLE

143 KB SINGLE, NO PS

$2605.00 $1895.00 $1145.00 $1045.00 $795.00 $695.00

SALE PRICE

$1395.00 $995.00 $695.00 $639.00 $625.00 $595.00

COMPLETE W/S-100 CONTROLLER, CABLES, MANUALS AND MICROPOLIS MDOS AND BASIC

ADD-ON DRIVES

MCP MCP MCP MCP MCP

■1033-2 •1023-2 ■1021-2 •1022-1 ■1021-1

630 KB DUAL

315 KB SINGLE

315 KB SINGLE. NO PS

143 KB SINGLE

143 KB SINGLE, NO PS

$1395.00 $645.00 $545.00 $545.00 $445.00

$895.00 $495.00 $475.00 $375.00 $360.00

REQUIRES ACCESSORY ADD-ON CABLES

GOOD NEWS FOR TRS-80* OWNERS

We now have a complete line of TRS-80* Model 1 compatible MICROPOLIS add on drives in matching colors. These drives simply plug into the expansion interface via a disc data cable.

197K BYTES PEE SIDE FOR YOUR TRS-80*, that's easy! Just order a 77 track add on drive and the New DOS-80 operating system. Among the many features of New DOS-80, is its ability to control any mix of 35, 40, or 77 track drives on the same cable.

TRS-80® DISK DRIVES

MCP-1027-1 MCP-1037-1 MCP-1027-2 MCP-1037-2

35 TRACK SINGLE 35 TRACK DUAL 77 TRACK SINGLE 77 TRACK DUAL

$545.00 $1195.00

$645.00 $1395.00

ACCESSORIES

PR1-34CEEE-2 PR1-34CEEE-4

NEW DOS/80 TRS-80"

35 Ihru 77 SUPPLIED

TRACK OPERATING 35 TRACK

SYSTEM $149.00

Two Drive Data Cable Four Drive Data Cable

GOODTHRU MARCH 1981

$279.95 $695.00 $439.00 $795.00

ON

77 TRACK

$159.00

$29.95 $39.95

THIS COULD BE THE START OF SOMETHING SMALL.

1-800-423-5633 PRIORITY ONE ELECTRONICS (213)894-8171

16723 B ROSCOE BLVD. • SEPULVEDA, CA. 91343

Terms: Visa. MC BAC, Check, Money Order, U.S. Funds Only. CA residents add 6% sales tax, Minimum order $15.00 Prepaid U.S. orders less than $75.00 include 5% shipping and handling. MINIMUM $2.50. Excess refunded. Just in case ... please include your phone no. Prices subject to change without notice. We will do our best to maintain prices thru March 1981. •SOCKET and CONNECTOR prices based on GOLD, not exceeding $700 per oz.

'Sale Prices are lor prepaid orders only. Credit card orders will be charged appropriale freight

'TRS-80 is a rectislered trademark of Tandy Corn

Circle 322 on inquiry card

S-100 HEADQUARTERS

THE DUAL PROCESSOR BOARD IS HERE!

GBT161 8085 CPU BOARD GBT1612 8085/8088 CPU BOARD

• 8088 & 8085A CPU

• S-100 IEEE COMPATIBLE

• SWITCHABLE CPU'S

• 5 MHZ OR 2 MHZ SWITCHABLE

• POWER ON JUMP TO ANY 256 BYTE BOUNDARY

• POWER ON JUMP CAN BE DISABLED

• CPU CAN JUMP ON POWER ON ONLY OR POWER ON AND RESET.

• 24 BIT EXTENDED ADDRESSING

• IMSAI FRONT PANEL COMPATIBLE

• AVAILABLE WITH 8085A ONLY

BOARD WITH B085 ONLY

List Price Our Price GBT161A Assembled & Tesled $325.00 S305.00

BOARD WITH 8085 & 8088

GBT1612A Assembled & Tesled $42500

S399.00

ENHANCED Z80 S-100 CPU BOARD

GBT160 Z80 CPU

• 4-6 MHz Z80 CPU

■ IEEE S-100 Bus Compalible

■ On Board Prom Sockets For Up To 8K Prom

• Power On Jump Start To Any 256Byte Boundary

• On Board Memory Manager For Direct Addressing For Up To 16 M-Byles

■ Fully Maskable Vectored interrupts

• Wait Stale Generation For All Machine Cycles

■ Bypassing Of All Supply Line To Suppress Transients

• All IC's Are Socketed

List Price

GBT160U Unkil

GBT160A Assembled & Tested

SPECTRUM S-100 COLOR GRAPHICS BOARD

• Uses the MC6B47 LSI IC

• Uses 1372 color encoded/generator

• Alphanumeric/graphics in 8 colors

• Ultra dense 256 x 192 lull graphics

• 8K bytes, on-board low power RAM

• One lull duplex parallel 1/0 port with attention, enable & strobe bits with powerfor running joysticks, keyboards, etc.

• A parallel port for graphics mode control

• Board may be used as a 4MHz RAM for program storage

LIST PRICE OUR PRICE

GBT144U GBT144A

UNKIT A&T

S399.0D

GBT2D SUBL0GIC UNIVERSAL GRAPHICS INTERPRETER SOFTWARE

S299.00 S349.0D

$35.00

INTERFACER I

Our 1/0 board gives you inparalleled flexibility and operating convenience. We include suchteatures as:

• 2 independently addressable serial ports (dip switch selectable addresses)

• Real LSI Hardware UARTs lor minimum CPU housekeeping

• RS232C, current loop (20mA). & TTL signals on both ports

• Precision, crystal-controlled Baud rates up to 19.1 KBaud (Individually dip switch selectable)

• Transmit & receive interrupts on both channels, jumperable to any vectored interrupt line

• Industry standard RS232 level converters with five RS232 handshaking lines per port

• Optically isolated current loop with provisions for both onboard & olf-board current sources

• UART parameters, interrupt enables. & RS232handshaking lines are software programmable with power-on hardware default to customer specified hard-wired set tings for maximum flexibility

• Port connectors mate directly to ribbon cable & DB25connectors in standard pinouts

• RS232 lines will conform to either master or slave configurations

• Board gives full feature operation with both 2 & 4 MHz systems

• Low power consumption:+8V@450mA; +16V@ 150m A; -16V @ 70mA max.

• No software initialization required for board operation, although board parameters may be altered by software

LIST PRICE OUR PRICE GBT133U UNKIT S199.G0

GBT133A AST $249.00 S219.00

INTERFACER II 3PTS

• 1 independently addressable serial port

• RS232C: 20mA current loop, & TTL signals

• Precision cry st a I controlled Baud rate generator

• Up to 19.2K Baud

• Transmit and receive interrupts, jumperable to and vectored interrupt line

• Five RS232 handshaking lines

• Optically isolated current loop

• 3 parallel I/O

• Utilizes LSTTL octal latches for latched I/O data with 24mA drive current

• Enable & strobe bits on each port (each with selectable polarity)

• Interrupts for each input port

• Separate 25 pin connector with power (or each channel and a status port for interrupt mask & port status

LIST PRICE OUR PRICE

ECONOROM 2708

Has provisions for wait states for 4MHz operations. Configured as four 4K blocks—each independently addressable and disabable. Power-on jump. Does NOT include 2708s. Includes all support chips, sockets, regulators, heat sinks, etc. Sold in UNKIT form only. Shipping Weight 2 lbs. GBT125U Unkit S85.00

;.M

Afrit

Order No. GBT129A32

CONORAM XA32K RAM

Reg. $689.00

Sale Priced $429.00

' 4MHz with Z80

■ 5MHz with 8085 • Assembled and Tested ' S-100 Compatible

■ Fully Static ' 24 Bit Extended

Addressing

Static S-100 Memory

32K ECONORAMXX

32K Bank Select. IEEE S-100 compatible. Features one 32K block that can be addressed on 4K boundaries. Compatible with the IEEE proposed standard of 24 address lines as well as all currently used bank select configurations. Any or all of the eight 4 K byte blocks may be disabled to create as many windows in memory to avoid any system memory conflicts.

List Price Our Price

GBT164A16 16K RAM A&T $399.00 S329.00

GBT164A24 24K RAM A&T $539.00 S455.00

GBT164A32 32K RAM A&T $699.00 $569.00

8K ECONORAM HA

We realize that this may not look like the 8K. Econoram II board you've known and loved for so many years; however, at Godbout, good things don't come to an end —they just get better! Our NEW 8K Econoram HA board retains all the best selling features of the old Econoram II PLUS is now 4 MHz STANDARD —still static—with ultra low power consumption. S-100 compatible. Single supply required—guaranteed maximum current under 900mA. Typical boards draw 700 to 800mA. Phantom feature is included on the new Econoram MA & is switch selectable. Orgai itzed as two 4K independently addressable blocks. Includes switched WRITE protect —block & board disable. Also, has provision for memory management. Shipping Weight 2 ,bs- Lisf Price Our Price

GBT139U Unkit S159.00

GBT139A A&T S189.00 S179.00

PRIORITY ONE ELECTRONICS

16723 B ROSCOE BLVD. • SEPULVEDA, CA. 91343

Terms: Visa. MC. BAC, Check, Money Order. U.S. Funds Only. CA residents add 6% sales tax Minimum order $15.00 Prepaid U.S. orders less than $75.00 include 5% shipping and handling. MINIMUM $2.50. Excess refunded. Just in case ... please include your phone no. Prices subject to change without notice. We will do our best to maintain prices thru March 1981. •SOCKET and CONNECTOR prices based on GOLD, not exceeding $700 per oz.

'Sale Prices are for prepaid orders only. Credit card orders will be charged appropriate freight

ECONORAM XIV

16Kx8forS-100. Addressable on any 4K boundary Direct addressing on up to 24 address lines. Fully meets IEEE S-100 buss specs. Low power, hi-speed static memory. Operates up to 5 MHz with newest 8085/8086/8088 CPUs. Can be used with 8080, Z80. 8085, 8086. 8088, Z8000, etc.

List Price Our Price

GBT143U Unkit S279.00

GBT143AA&T $349.00 $299.00

ORDER TOLL FREE 1-800-423-5633 ORDER TOLL FREE 1-800-423-5633

BITS & PIECES

TRS-80/APPLE

MEMORY EXPANSION KITS c 4116's RAMS

A/ from Leading Manufacturers (Eft. #

4^ (16Kx1 20Qns) W

/8 for *2900 <

ADD S3.00 FOR PROGRAMMING JUMPERS FOR TRS-80 KEYBOARD

4116's 100 pes & UP $3.00 each 1000 pes & UP $2.75 each

2114-3L

I4096 BIT (1024x4) 300ns I LOW POWER STATIC RAM

8/s3000

100 + s300

5257-3L

(TMS 4044)

4096x1 300ns

| LOW POWER STATIC RAM

8/s5000

100 pes. + s475

2716

450ns 5 Volt only 16 K EPR0M

s1195 each or 10/s8500

2708

450ns 8K EPR0M

s850 each or 8/s5400

2732

450ns 5 Volt only 32 K EPR0M 8x4K

$25.00 8/M60.00

ZERO INSERTION FORCE TEST SOCKETS

II"'^-

\"

1

1-9 10-24 25-99

2IP-160IP S5.50 5.35 4.95

ZIP-24DIP S7.50 7.25 6.95

ZIP-40DIP S10.25 9.85 9.50

3 LEVEL GOLD WIRE WRAP SOCKETS PRICE*

-•-■• S»K,

DIP SWITCHES SPST

PART ND. NO. Of POSITIONS |-9

PRICE 1024

25-99

DIP-SW4 DIP-SW5 DIP-SW6 0IPSW7 DIPSW8 DIP-SW9 OIPSWIO

SI. 50 S1.B0

SI.70 SI.80 S2.00 S2.25

S2.50

SI.40 SI.49 SI.59 SI.66 SI.86 S2.I0 S2.33

S1.28 SI.36 SI.45 SI.53 SI.70 SI.92 S2.I2

^.Shugort

ISA801R SALE

/

SHU-SA801R

2 OR MORE

395

$410°

00

ea.

Capacity

Single Density

Double Density

Unformatted

Per Disk

3.2 megabits

6.4 megabits

Per Track

41 7 kilobits

83.4 kilobits

IBM Format

Per Disk

2.0 megabits

n/a

Per Track

26.6 kilobits

n/a

Transfer Rate

250 kilobits/se

c. 500 kilobits/sec.

Latency (average)

83 ms

83 ms

Access Time

Track to Track

8 ms

8 ms

Average

260 ms

260 ms

Setting Time

8 ms

8 ms

Head Load Time

35 ms

35 ms

CT/M

vi

*sum2.*Z

; SI CCS2422A FLOPPY DISK CONTROLLER ,_

WITH CP/M VERSION 2.2 $375.00

LIST $400.00

SALE

IEEE S-100 COMPATIBLE SINGLE/DOUBLE DENSITY 5'.'78" DISK DRIVES SINGLE/DOUBLE HEADED ASSEMBLED & TESTED

' ;; V

Aferbatim

Pari No.

VRB-MD 525-01 VR8-MD 525-10 VRB-NID 525-16 VRB-MD 577-01 VRB-MD 577-16 VR8-F032-1000 VRB;F034-1000

Sectoring

Soft Sector Hard to Sector Hard 1G Sector Sott Sector Hard 1G Sector Hard Seclor Solt Sector

Application

TRS-80 Apple North Star Micropolis 77 Track Cert 77 Track Cert Sliugart 801R IBM 3740

S29 S29 S29 S48 S48 S37 S37

MODEI

$129.00]

THE STAR

MODEM

from LIVERMO

FEATURE

FITS GTE HANDSETS!

2 YEAR WARRANTY

EXCLUSIVE ACOUSTIC CHAMBERS

The exclusive triple seal of Livermore s new flat mounted cups locks the handset into the acoustic chamber yielding superior acoustic isolation and mechanical cushioning. Designed to adapt to most common handsets used throughout the world, the STAR offers the utmost in flexibility and transmission reliability.

Specifications:

■ Data Rate: 0 to 300 baud

• Compatibility: Bell 103 and 113; CCITT

■ Frequency Stability: ±0.3 percent. Crystal controlled

• Receiver Sensitivity: -50 dBm ON, -53 dBm OFF

• Modulation: Frequency shiftkeyed (FSK)

■ Carrier Detect Delay: 1.2 seconds ON; 120 msec OFF

■ EIA Terminal Interface: Compatible with RS 232 specifications

■ Teletype Interface: 20 milliampere current loop

■ Optional Interfaces: IEEE 488; TTL; TTY 43

• International (CCITT) frequencies available

• Switches: Originate/Off/Answer: Full Duplex/Test/Half Duplex

• Indicators: Transmit Data, Receive Data. Carrier Ready, Test

• Power: Supplied by 24 VAC/150 MA UL/CSA listed wallmount transformer Input 115 VAC. 2.5 watts. (A 220 VAC. 50 Hz adaptor is available upon request.)

• Dimensions: 10" x 4" x 2"

■ Weight: 1.74 lbs. (3 lbs shipping weight including AC adaptor.)

■ Warranty: Two years on parts and labor, excluding the AC adaptor which carries the manufacturer's warranty

List SALE

Price PRICE

S19900 S129.00

S19900 S129.00

$229.00 S209.00

$395.00 $249.00

S465.00 S388.00

Part No Description

LIV-STAR RS232,TTL Modem

LIV-STAR20M RS232, 20MA Current Loop

LIV-STAR-V21 CCITT European Standard

LIV-IEEE IEEE 488 Standand

LIV-IEEE-V21 IEEE 488. CCITT Standard

CABLES

Part No. Description -^H |^ Price

CND-RS2328F RS232 8 Cond 8 ft 7WTT. . S19.95

LIV-I2I IEEE to IEEE 2 Meter .» $59.95

LIV-I2PET IEEE to Pet 2 Meter S59.95

PROTECT YOUR INVESTMENT PROTECT YOUR DATA WITH

<*^

ISDBflR

GOF-IBAR46

♦/

)95

LIST PRICE S799 SALE PRICE S3995

GOLD S-100 CONNECTORS

PRIORITY ONE distributes the Tl S-100 Card Edge

Connectors at tremendous volume for prices

others only wish they could duplicate.

SOLDER TAIL PRICE 10-24 25-99 100-249

TI-S100STCT 3.20 2.90 2.50 2.20

WIRE WRAP PRICE

Part No. 1-9 10-24 25-99 100-249

TI-S100WWG 4.00 3.75 3.50 3.25

PRIORITY ONE ELECTRONICS

16723 B ROSCOE BLVD. • SEPULVEDA, CA. 91343

Terms: Visa, MC. BAC. Check. Money Order, U.S. Funds Only CA residents add 6% sales tax. Minimum order $15.00 Prepaid U.S. orders less than $75.00 include 5% shipping and handling. MINIMUM $2.50. Excess refunded. Just in case ... please include your phone no. Prices subject lo change without notice. We will do our best to maintain prices thru March 1981. •SOCKET and CONNECTOR prices based on GOLD, nol exceeding $700 per oz. 'Sale Prices are fcr prepaid orders only Credit card orders will be charged appropriate freight

lA

ORDER TOLL FREE 1-800-423-5633 ORDER TOLL FREE 1-800-423-5633

Circle 323 on Inquiry card.

Best Prices and Delivery^

I

SU;: , tIN byfntertec

Selt contained computer with duat disks and two RS232C ports. Complete with CP.'M' 2.2 and BASIC.

32K Double Density, List $2995 .

64K Double Density, List $3345 $2883

64K Upgraded to Quad Density w/ Special MiniMicroMart Warranty SPECIAL $3395

VIDEO TERMINALS

/VflrV EMULATOR (Intertec), List $895$ 749 NEW INTERTUBE IIIList $895 . . ONLY $ 749 SOROC 120, List $995 SPECIAL $ 729

1Q140, List $1495 SPECIAL $1149

PERKIN-ELMER 550, List $997 $ 799

with anti-glare screen, $1027 $ 829

HAZELTINE 1410, List $900 $ 749

1420 $ 849

1500, List $1225 $ 879

1510, List $1395 $1089

1520, List $1650 $1389

LEAR SIEGLER ADM3A, Assembled $ 849

TELEVIDEO 912C, List $950 $ 789

920C. List $1030 $ 849

950C, List $1195 NEW $1039

PRINTERS

ANADEX DP-8000 $ 849

DP-9500, List $1650 $1399

DP-9501, List $1650 $1399

PAPER TIGER IDS-445, List $995 $ 695

w/graphics op., incl. buffer, $1195 .. $ 789

PAPER TIGER IDS-460, List 1149

PAPER TIGER IDS-460G List 1199

NEW IDS PAPERTIGER460 . List 1295 11149 NEW IDS PAPERTIGER 460G List $1394 {1199

NEC Spinwriters Call for Price

TELETYPE 43 KSR $1087

CENTRONICS 730-1 parallel interface . . NEW LOW $ 649 737 parallel interface . SUPER VALUE $ 829 779 w/Tractor, List $1350 $1049

703 w/Tractor, VFU, List $2975 $1695

704 w/Tractor, VFU, List $2350 $1595

Tl 810 Basic, List $1895 $1695

810/serial & Centronics-style

parallel interface, List $1940 $1735

810 w/full ASCII (U/LC), Vertical Forms Control, Compressed Print . . $1895

Tl 820 KSR, List $2165 $1835

Tl 745 w/full ASCII, List $1695 $1399

COMPRINT 912 w/parallel interface . . $ 559

912 w/serial interface, List $699 $ 589

AXIOM IMP I $ 699

MICROTEK, List $750 $ 675

OKIDATA Microline 80, List $949 $599

Tractor Feed Option $109

RS232 Serial Interface $ 99

NORTH STAR HORIZON"

HORIZON 1 ASSEMBLED it TESTED

32K, Double Density, List $2695 .... $2279 32K, Quad Density, List $2995 $2539

HORIZON 2 ASSEMBLED & TESTED

32K, Double Density, List $3095 $2619

32K, Quad Density, List $3595 ... $3049

48K, Double Density, List $3590 $3039

48K, Quad Density, List $4090 $3469

64K, Double Density, List $3830 $3239

64K, Quad Density, List $4330 $3669

FLOPPY DISK SYSTEMS

NORTH STAR MDS-A Assembled, List $899 SPECIAL $ 719

MORROW THINKER TOYS" Discus 2D,

List $1199 OUR PRICE % 998*

Discus 2D, dual-drive. List $1994 $1694*

Discus 2+ 2, A&T, List $1549 $1319*

Dual Discus 2 + 2, A&T, List $2748 . . . $2335* •Now includes CP/M- 2.2

Prom Programers

SSM PB1 Kit List $1 25 $106

SSM PB1 A&TList$190 $161

SD Computer Prom 100 Kit$236 $201

SD Computer Prom 100A&T List $311 . . $264

FLOPPY DISK CONTROLLER BOARDS

NORTH STAR, DD,

Assembled, List $499

MORROW Disk Jockey 1, A&T ($213)

Disk Jockey 2D, A&T, List $479

SD Versafloppy 1, Kit, List $284

Versafloppy II, DD Kit, List$413

Versafloppy II, DD, A&T, List $507 . . . DELTA double density A&T ($385) . . CONDUCTOR, double density A&T INTERSYSTEMS FDC-2, A&T, $495 MICROMATION Doubler, DD, A&T TARBELL Floppy Disk Interface Kit .

double density, A&T, List $495 ....

$399 $189 $429 $239 $349 $429 $345 $269 $439 $429 $199 $444

:

ESCON CONVERSION FOR IBM SELECTRIC

Complete w/microprocessor controller qnd power supply Factory built. User installs solenoid assembly or it can be done at Escon factory at nominal cost. Parallel (TRS-80, Sorcerer, etc.), $575 $514

RS232 Standard Serial, List $599 534

IEEb-'t88 (for PET), List $660 584

TRS-80 Cable 25

CALIFORNIA COMPUTER SYSTEMS

Z80 CPU BOARDS List $299 $269

DISK CONTROLLER 2422 List $399 $359

16K Static, A&T, List $349.95 $259

32K STATIC List $71 0 $599

64K DYNAMIC BOARD List$699 $589

CPU BOARDS

(assembled unless noieoi NORTH STAR Z80A (ZPB-A/A), $299 $254 CROMEMCO 4 MHz (ZPU-W), List $395 $335

4 MHz (SCC-W), List $450 $382

INTERSYSTEMS (formerly Ithaca Audio) new Series II Z-80, 4 MHz. List $395 . $349

SSM CB1 8080 A&T List $252 $214

CBIAKit, List $183 $156

CB2 Z-80, A&T, List $344 $289

CB2 Kit, List $60 $221

DELTA Z-80, with I/O $289

SD SBC-100, List 413 $349

SBC-100 Kit, List $341 $289

SBC-200, List $471 $399

SBC-200 Kit, List $373 $317

MEMORY BOARDS

32K SD ExpandoRAM Kit

! I

CALL FOR PRICES

NORTH STAR 16K Dynamic RAM Board,

A&T (RAM-16-A/A), List $499 $420

32K A&T (RAM-32/A), List $739 $620

CROMEMCO 16KZ-W, List $49b $419

64KZ W, List $1795 $1269

MEASUREMENT SYSTEMS & CONTROLS

(Guaranteed performance, incl. labor/parts 1 yr) DM6400 64K Board w/all 64K, $795 . . . $659

DM4800 with 48K, List $695 $650

DM3200 with 32K, List $595 $509

DMB6400 64K Board w/all 64K $859

DMB4800 with 48K $789

MORROW SuperRAM - all static, all A&T

16K, 4 MHz or 2 MHz, List $349 $299

32K, 4 MHz, List $699 . $629

16K Memory Master, List $399 $339

24K Memory Master, List $549 $465

INTERSYSTEMS (formerly Ithaca Audio)

8K Static 2 MHz, A&T, List $165 $149

8K Static 4 MHz, A&T, List $195 $176

16K Static 2 MHz, A&T, List $475 $427

16K Static 4 MHz, A&T, List $495 ..... $445 64K Dynamic, List $995 $895

CALIFORNIA COMPUTER

16K Static, A&T, List $349.95 $259

VIDEO BOARDS

I/O Mapped SD COMPUTER VDB-8024, kit, List$437 .369

Assembled, List $556 $469

XITEX SCT-100K, Kit ONLY $169.95

SCT-100A Assembled $189.95

SSM VB2 I/O, Kit, List $199 $169*

Assembled & Tested, List $269 $229*

Memory Mapped SSM VB1C, 16x64, Kit, List $179 $152*

Assembled & Tested, List $242 $206 *

SSM VB3, 80-Char.,4MHz,Kit, List$425 . . $359*

4 MHz, A&T, List $499 $424

INTERSYSTEMS, lbxt>4, A&T, List $1bb $149 *Subject to change.

NEW CROMEMCO 16FDC

DISK CONTROLLER

List $595 OUR PRICE

SHIPPING AND INSURANCE: Add $2.50 (or boards, $6 for Selectric Convener or Floppy Disk Drives, $7.50 for Floppy Disk Systems, $15 for Horizon SHIPPED FREIGHT COLLECT; SupeiBram, Centronics

and T.I printers. Contact us for shipping information on other terminals and printers.

Above prices reflect a 2% cash discount (order prepaid prior to shipment) Add 2% to prices lor credit card orders. C.O.D.'s. etc. Prices are subject to change and offers subject to withdrawal without notice.

- WRITE FOR FREE CATALOG

Circle 324 on inquiry card.

MiniMicroMart, Inc.

1618 James Street, Syracuse NY 13203 (315)422 4467 TWX 710-541-0431

Terminals anH Printers!

mm ^tmmW mm mm mm mm mm Bm mm mwwmm mm m*mmW fo^f m m ^mm mm mm JSb mm mm mmm ^tmlm^ mm ^9mm^ mm

TELEVIDEO TVI-912C

SOROC

TI-810

in inn niiiiiiiu wvvww

mum wwww

Mtmftv

Upper and lower case, 15 baud rates: 75 to 19,000 baud, dual intensity, 24 x 80 character display, 12 x 10 resolution. Numeric pad. Programmable reversible video, auxiliary port, self-test mode, protect mode, block mode, tabbing, addressable cursor. Microprocessor controlled, programmable underline, line and character insert/delete. "C" version features typewriter-style keyboard. List $950

OUR PRICES?6a 920C (with 11 function keys, 6 edit keys and 2 transmission mode keys, List $1030

ONLY $849

New 950C $1195 $1039

Intertec

EMULATOR

Software compatible with a Soroc IQ-120, Hazeltine 1500, ADM-3A or DEC VT-52. Features block mode transmission and printer port; 12" anti-glare screen; 18-key numeric keypad; full cursor control. List $895

NEW INTERTUBE III

List $995 12" display, 24 x 80 format, 18-key numeric keypad, 128 upper/lower case ASCII characters. Reverse video, blinking, complete cursor addressing and control. Special user defined control function keys, protected and unprotected fields. Line insert/delete and character insert/delete editing, eleven special line drawing symbols.

IQ-120

List $995

-140 List $1495

afCi<iAl. ? l I-*:!

HAZEi™e

1500

1410 w/numeric keypad, List $900 $749

1420 w/lower case and numeric pad 849

1510, List $1395 1089

1520, List $1650 1389

Terminal/Keyboard as well as

RO Printer Only models available.

CALL FOR PRICES!

PRINTERS

NEW 730-1, parallel, friction, tractor . . $649 NEW 730-3 RS-232 friction, tractor . . . .$699 NEW 737-1 parallel, friction, tractor.... $829 NEW 737-3 RS-232 friction, tractor . . . .$899 779-2 w/ tractor (Same as TRS-80 Line

Printer I), List $1350 $849

704-11 parallel 180 cps $1698

704-9 RS232 serial version, $2350 . . $1595

TI-810 Basic Unit, $1895 .

TI-810 w/full ASCII (Lower case), vertical

forms control, and compressed print . $1795 TI-745 Complete printing terminal with acoustic coupler, List $1695 ....

RNRD6X

DP9500/DP9501 PRINTCRS

DP-9500, List $1650 $1349

DP-9501, List $1650 $1349

OKIDATA Microline80

Tractor Feed Option $109

Serial interface $ 99

AXIOM IMP I $699

COMPRINT 912 w/parallel interf. $559 912 w/serial interface. List $699 $589

MICROTEK. List $750 $675

NEW MODELS.'.'.'

DP9500 $1349

DP9501 $1349

^% M. ■"* HP* P^§ *W*U tf"% f~ 9% *

i E

IDS-445 Paper Tiger, $695

w/graphics option, incl. buffer, $1194 . . $789

TRS-80 cable $45

NEW IDS PAPERTIGER 460List $1295 . $1099 NEW IDS PAPERTIGER 460G List $1394 $1149

NEW IDS 460

QUALITY PRINTING AT MATRIX

SPEEO-LOGIC SEEKING

PROPORTIONAL SPACING

w/aufo text justification

Above prices reflect a 2% cash discount (order prepaid prior to shipment). Add 2% to prices for credit card orders, C.O.D.'s, etc. Prices are f.o.b. shipping point. Prices are subject to change and offers subject to withdrawal without notice. WRITE FOR FREE CATALOG.

MiniMicroMart, In

1618 James Street, Syracuse NY 13203 (315) 422-4467 TWX 710-541-0431

Circle 325 on Inquiry card.

VISA'

Smtm

Unclassified Ads

UNCLASSIFIED POLICY: Readers who are soliciting or giving advice, or who have equipment to buy, sell or swap should send in a clearly typed notice to that effect. To be considered for publication, an advertisement must be clearly noncommercial, typed double spaced on plain white paper, contain 75 words or less, and include complete name and address information.

These notices are free of charge and will be printed one time only on a space available basis. Notices can be accepted from individuals or bona fide computer users clubs only. We can engage in no correspondence on these and your confirmation of placement is appearance in an issue of BYTE.

Please note that it may take three or four months for an ad to appear in the magazine.

FOR SALE: Two cassette interfaces: Tarbel I; $75, Da Jen; $120. Seven 8 K static programmable memory boards; $90 each. Expandorom 2708/16 (less PROMs); $50. Two SSM 4 K 1708 boards; $35 each. 8-Inch single disk drive cabinet with power supply which will run two drives, Shugart Siemans compatible; $175. PTC VDM-1 video driver board; $150. Ail working and assembled. Ail S-100 bus. Dick Drain, 6730 Alter Rd, Dayton OH 45424, (513) 233-8055.

FOR SALE: S-100 and other items; Cromemco: ZPU processor board, 8 K Bytesaver, 16 K programmable memory, PRI printer interface, D + 7A analogue I/O. IMSAI: card cage and 28 A supply, 16 K programmable memory board, 32 K programmable memory board, MIO multiple I/O, VIO-C video with all read-only memories. TDL: 16 K programmable memory Z16. OAE paper-tape reader. Radio Shack keyboard. Keytronlc capacitive keyboard. Ail items like new and guaranteed working. Very reasonable prices. Bob Waber, 2590 #14 E Michigan, Ypsilanti Ml 48197,(313)484-1826.

WANTED: Assembly/Applesoft graphics programs, game programs, subroutines. All welcome for experiments with graphics. Stamps for interesting responses. Alan M Leder, 246 Lenox Ave, Paterson NJ 07502.

FOR SALE: Used S-100 boards: TDL Z80 processor board; $100, Scitronlcs control board; $100, MITS parallel I/O board (one port); $50, 8080 processor; $80. Paul Jacobs, 5201 E 3rd St, Tucson AZ 85711, (602) 795-2366.

NEEDED: Information, kit, schematics, or advice for adapting CP/M or equivalent operating system to the Intel SBC 80/10. Goal Is to run Pascal on the 80/10. Also, have DEC LA-36 for trade or sale. Scott Nlntzel, 3843 Granada Ln N, Oakdale MN 55109, (612) 770-6926.

FOR SALE: Pen plotter: Houston Instruments HIPLOT (tm) plotter. Uses 8 by 11 paper. Has serial and parallel interfaces. Perfect shape; $900. (New price is $1100.) Will ship COD. Harold Hedelman, 1020 Triphammer Rd, Ithaca NY 14853,(607)256-4880.

FOR SALE: Jade Z80 processor boar'd, 4 MHz, assembled and tested, unused, $140; GRI keyboard #753 (5 V), $50. K B Clark, 158 Creel, Palm Bay FL 32905, (305) 725-5130.

WANTED: Radio Shack expansion interface with or without RS-232C board. 0 K or 16 K memory. Marc Gedert, 619 W Broadway, Maumee OH 43537, (419) 893-0544.

WANTED: Need SwTPC MP-A or MP-A2 processor card or similar for S-50 bus. Prefer to have operating card, but will consider one that needs repair if necessary. (US Post Office domestic rates, $0.15 letters) George Keim, POB 160, Yap Island GU 96910.

FOR SALE: Used and unused hardware and software for TRS-80 Model I and CP/M systems. Send SASE for complete list. R Lee, 25 Amaryllis Ave, Waterbury CT 06710.

FOR SALE: Two EXECuport portable terminals: 10 thru 30 cps, 80-column printer modems. Both parallel and serial I/O ports for use as printer. See ad on page 217 of the March 1980 BYTE for details. Both units in good working condition. Will ship UPS COD, no risk, pay on delivery. Model #300-5375, #320-$475. Warren V Bell, 1604 N Smith St, Spokane WA 99207, (509) 534-8088 evenings.

WANTED: Apple, Pascal, and dual disks are the base of our research project to develop automated tools for high-level software and systems design architecture. Based on the Design by Objectives methods. We seek contact with hard-working colleagues prepared to contribute to development. MARK I system exists. Tom Glib and Lech Krzanik, Box 102, N-1411 Kolbotn, Norway.

FOR SALE: CAT-100 video digitizer with frame capture, full instructions, CP/M software, and source listing. It is a two-board system for S-100 bus and includes 32 K of programmable memory with full video and software I/O capability. It has sixteen levels of gray scale or sixteen colors arranged as 240 lines of 256 pixels. $1600 invested. $950/offer. John Underwood, 1171 NE 72nd, Portland OR 97213, (503) 252-7394.

FOR SALE: Ithaca Audio Z80 processor. 2.5 MHz with power on jump and selectable wait states, 2708 not included; $99. Vector 8803 motherboard with active termination and three S-100 connectors; $35. Roy Ortiz, 265 Beech St #21, Hackensack NJ 07601, (201) 488-5405.

The Sight of Music

Digital Harmony

by John Whitney

BYTE BOOKS is pleased to offer DIGITAL HARMONY a

major new work by John Whitney, a pioneer of the special effects technology used in STAR WARS and 2001: A SPACE

ODYSSEY. His book explores the special union of music and computer graphics, and expands the frontier between sight and sound, synthesizing the two to create a new art form. Whitney tells how it's done, provides a thorough theoretical background, and includes listings and programs for those interested in joining in the discovery of this new art form. DIGITAL HARMONY lays the foundation for audio-visual art made possible by microcomputers. It is must reading for all art, music and home computer enthusiasts.

Illustrated in Color.

Please remit in U.S. funds or draw on a U.S. Bank Please send G

copies of

Digital Harmony

Name

Title

Company

Street City

State/Province

Code

D Bill Visa D Bill Master Charge Card No.

F*n Rate

Add 75« per book to cover postage and handling.

KM*

Call TOLL FREE: 800-258-5420 or Mail To:

70 Main Street. Peterborough. N H 034S8

FOR SALE OR TRADE: Current model Mlnlterm portable computer. BASIC,6800 programming, resident debugger and editor, 32 K programmable memory, built-in microcassette (60 K storage), acoustic coupler, and serial interface. Also has all the features of a portable printing terminal. Disk system available. Other features too numerous to list. Will supply information. Sells new for $5000; will sell for $2500 or trade for 48 K Apple II with two disks and Pascal or similar system. Bob Edison, 215 Newton St, Waltham MA 02154, (617) 891-5618.

SWAP:KIM-1 microcomputerwith manuals, barely used, for a pair of Acoustic Research AR-3 speakers (not AR3a). Will pay shipping both ways. C Lee, 1021 Merritt Dr, Tallahassee FL 32301, (904) 878-1983.

FOR SALE: S-100 compatible, 16-bit 8088 single-board computer; all documents included. Never been used. Original cost of $400, will sell for$300. Trung Dae Lieu, Box 292,303 Stadium PI, Syracuse NY 13210.

FOR SALE: Two Pertec disk drives and controller. The drives worth $5000 when new; I will take $1500 or best offer. Both of the drives need some work. Comes complete with power supply, multiplexer boards, 8-Inch DOS disk, and complete documentation. (MCI—if wanted.) Will work on various microprocessors. Heinan Landa, 12109 Greenleaf Ave, Potomac MD 20854, (301) 279-9356.

FOR SALE: Computer Mart PME1 32 K memory board, which lifts an 8 K PET to a full 40 K. 8 K of this is addressable through machine language only. The PME1 board installs entirely inside the PET. I used it lightly for three months. Cost $750; asking $350. Philip Restagno, 2910 DeWitt PI, Bronx NY 10469, (212) 231 -2753.

FOR SALE: Back issues of BYTE, postpaid. Also, want 1975 and 1976 issues of BYTE. P Gray, 1505 NW 124th Ave, Portland OR 97229, (503)641-2747.

FOR SALE: Centronics P-1 printer, parallel, with cable; $250. SwTPC CT-64 terminal; $250. Hitachi 9-inch monitor; $75. SwTPC AC-30 tape controller; $75. All include manuals. Send 10% for COD, ppd orders sent ppd. Charles Shilling, 2003 Fair Meadow, Arlington TX 76012, (817)461-2239.

FOR TRADE: Want to swap cassette programs for TRS-80 Level II. Games, educational, and mathematics. No business programs. Send cassette with your address. Bob Trent, POB 298, Hardinsburg KY 40143.

FOR SALE: TRS-80 disk drive. Less than six hours use. Includes cable. $225. K J Morrison, 10513 Si Iverdale Way NW, Silverdale WA 98383.

FOR SALE OR TRADE: Assembler for 8080/85. Runs under North Star DOS V5.0. Written in BASIC, creates object file in North Star format. Included are source creator/editor and file dump programs (also in BASIC). Requires one minifloppy drive plus 32 K. Cost: $25; manual only: $5. W T Shaw, 13521 Blenheim Rd N, Phoenix MD 21131, (301) 667-4800.

USED COMPUTERS: Send information on microcomputers you or a friend have sold—make, model, configuration, month sold, price. I'll send a summary of other people's prices in return. Bruce Lynch, 2905 Blue Robin, Herndon VA 22071.

FOR SALE: ESCON Universal Interphase RS-232 for IBM Selectric II typewriter. B K Parekh, (406)365-3393.

FOR SALE: Novation Model 4202B modem, 1200 bps, originate/auto-answer, direct connect, 2-wire dial-up or 4-wire; $496. Philip Nunn, 201 Netherfield, Comstock Park Ml 49321, (616)361-8681.

FOR SALE: Heath H-9 video terminal expertly assembled, in very good condition; $200. Also, YAESU FR-101, FL-101 with converter boards, filters, clock, and all documentation in English; $900. Mint condition. Mark Miller, 9573 Walley Ave, Philadelphia PA 19115, (215) 698-1905.

FOR SALE: Apple graphics tablet, cost $795, sell $600. Mountain Hardware 388 day clock, cost $199, sell $140. Mountain Hardware Romplus with keyboard filter, cost $169, sell $125. Above items in like new condition and were used less than three hours each. Will be shipped in original cartons with all documentation. Earl A Loobey, FSI/POB 487, Fairbanks AK 99701.

FOR SALE: Digital Group microcomputer. Z80 and 6800 processors, 50 K memory, sixteen parallel ports, front panel, 16 by 64 video display, Marantz tape deck, keyboard, Sanyo monitor, Maxi-BASIC, Super Games, FigFORTH documentation, plus much more software and full hardware documentation. Complete system $2000or best offer. Dennis Ruffer,423 Garfield St, Kalamazoo Ml 49001, (616)381-8747.

FREE PROGRAMS: As a high school science teacher using a 16 K Apple II Plus, I have had difficulty in locating programs for class use. Since commercial programs are expensive and often not suited for use with high school students, I have written several programs in Applesoft BASIC for use in my physical science, biology, and chemistry classes. If anyone is interested in obtaining a copy of one of these programs, please send me a SASE and I will send you a complimentary copy. William R Ground, J L Mann High School, 61 Isbell Ln, Greenville SC 29607.

FOR SALE: Heath H-11 system, LSI-11 with 40 K bytes memory, CRDS double-density floppies, H-10 paper-tape reader/punch, serial and parallel interfaces.$6400 value, asking $4800. Add $650 for factory-assembled H-19 terminal. Jeff Goldberg c/o CRDS, 4 Tech Cir, Natick MA 01760, (617)655-1800.

FOR SALE: Apple II DOS 3.3 upgrade kit, including readonly memories, disks, and manual; $35. Joel Buckley, 1212 Broadway, Hanover PA 17331.

FOR SALE: Heathkit ET-3400 and program for same. Good condition. Will sell to the best offer. Ralph Swearingen, 7213 Loras Ln, Wonder Lake IL 60097, (815) 653-7821.

BOMB

BYTE's Ongoing Monitor Box

Article #

1

Page 20

36

3

54

4

84

5

90

6

132

7

166

8

262

9

300

10

317

Article

Structured Programming and Structured

Flowcharts

Build the Disk-80: Memory Expansion and

Floppy-Disk Control

Three-Dimensional Computer Graphics, Part 1

The Micro Matrix Photopoint Light Pen

What's Inside Radio Shack's Color Computer?

What Is Good Documentation?

A Beginner's Guide to Spectral Analysis, Part 2

A Simple Approach to Data Smoothing

The New Literacy: Programming Languages as

Languages

Computer Music: A Design Tutorial

Author(s)

Williams

Ciarcia

Crow

Gray

Ahrens, Browne,

and Scales

Howard

Zimmermann

Ruckdeschel and

Krinsky

Handel Orlofsky

FOR SALE: North Star disk controller board. Singledensity, excellent condition. Selling due to an upgrade on my present system. Lots of software, including North Star DOS and BASIC, CP/M, assemblers, games, and lots more. Will run Pascal, FORTRAN, ALGOL, C, and many others. Asking $250. Mark Sauerwald, 7872 Caminito Huerta, San Diego CA 92122, (714) 453-1206.

FOR SALE: North Star controller and software (fifty diskettes); $350. Eprom board, holds sixteen 2708s;$60. Rack-mountable Integrand cabinet; $120. Vector elevenslots motherboard with connectors; $50. TDL processor; $100. TDL monitor board; $150. TDL cassette software (Assembler, 12 K BASIC, Text Editor, text output processor); $200. Mohammad Mandurah, POB 4272, Stanford CA 94305, (415) 328-3959.

WANTED: Apple II with at least 32 K memory and disk drive. Prefer dual-disk drive. All replies will be answered. Send complete name, address, and phone. Scott Emmons, 1225 Nord Ave #166, Chico CA 95926, (916) 893-5311.

WANTED: Data for Processor Technology GPM-1 board (9 K read-only memory, 1 K programmable memory). Also require for S-100 bus, a cassette UO prom programmer and disk controller, any make. Consider anything from bare board with data, to working. Please state price required. Larry Dass, 4, Nancevallon, Brea, Camborne, Cornwall, England, phone 0209 714475.

FOR SALE: Heathkit H-14 printer ready to connect to Heathkit, Zenith, or North Star Horizon computer. Features include RS-232 interface, uppercase/lowercase, up to 132 columns wide, adjustable tractor feed to 9.5 inches wide, maximum 165 cps print speed. Unit is in perfect condition. Full documentation and original carton included; $575. Brian Stotesbery, 2544 Second Ave S, Minneapolis MN 55404, (612) 872-0804.

SWAP: TRS-80 machine language and BASIC programs, Level II and Disk BASIC. Send your list of programs to trade, and I'll send mine. Steven Kliewe, 9005 Vickery Rd, Tacoma WA 98446.

FOR SALE: Hewlett-Packard 608D VHF signal generator. Like new, $350. Also, eight computer power supplies, four chart recorders, pulse generator, square-wave generator. W L Pierce, 703 23rd St S, Arlington VA 22202, (703) 525-3223.

WANTED: Processor board for SwTPC 6800 computer. Garth Fisher, Department of Industrial Technology, Walla Walla College, College Place WA 99324.

Opinions and Games Win December BOMB

Computer games of all kinds caught our readers' fancy. Jerry Pournelle's popular User's Column won first place in the December 1980 BOMB; this time, Jerry wrote about "BASIC, Computer Languages, and Computer Adventures." P David Lebling's article "Zork and the Future of Computerized Fantasy Simulations" captured second. The next three places went to "Multimachine Games" (Ken Wasserman and Tim Stryker), "On the Road to Adventure" (Bob Liddil), and "Pirate's Adventure" (Scott Adams).

March 1981 © BYTE Publications Inc 383

Reader Service

Inquiry No.

Page No.

63

91

320

141 256 272

36

82 275 307

32 263 123 148

48 319

12 192 147

244 116 131 268

311 188 199 150

115 298 310 128

16 321 202 248 296 162 117 168

17 326 223

39 217 206 100

120 238

181

299

292

43

243

291 59

227 38

318 59 42

221 64

323

1

44

312

278

35

18 251

57 118

97 157 130

61 166 156

72

19

137 231

250 138

210 329 176

Aardvark Software Inc 117

Aardvark Software Inc 162

AB Computers 361

Abbott, Robert 354

ABM Products 222

Ackerman Digital 339

ACOM Electronics 277

Action Computer 63

Adaptive Data & Energy Sys 146

Advanced Comp Prod 348, 349

ALL Electronics 356

Alpha Byte Storage 59

Alpha Omega Comp Sys 275

Am Micro Prod Inc 198

American Square Comp 231

Anadex 89

Ancrona 360

Anderson Jacobson 16

Anderson Jacobson 279

Andromeda Systems Inc 230

Apple Computer 13

Applied Analytics 318

Artec Electronics 328

ASAP 187

Ashton-Tate 211

Atlantis Computerized Serv 277

ATV Research 354

autocontrol Inc 356

Automated Equip Inc 274

Automated Equip Inc 283

BASF Systems 233

John Bell Engineering 347

Beta Comp Devices 186

Bit Bucket, The 354

Blacksburg Grp Inc, The 356

Bower-Stewart & Assoc 204

BYTE Books 51, 201, 382

C & A Associates 350

Calif Comp Systems 21

Calif Digital 374, 375

Cambridge Develop Labs 285

Cawthon Scientific Grp 330

CBAS 354

Central Data 251

Cexec Inc 190

Chrislin Industries 255

C. ITOH Electronics Inc 23

Clev Con Comp & Compnts 365

Cognitive Systems 297

CompuMart 68, 69

Computer Age Inc 293

Computer Case Co 287

Computer Disc of Am 174

Computer Factory, The 115

Computer Furn & Access 194

Computer Marketing Corp 320

Computer Plus 268

Comp Prof Book Club 208, 209

Computer Shopper 354

Computer Society 352

Computer Specialties 76, 77

Computer Tech Inc 326

Computer Warehouse 85

Computers Plus Inc 352

Computers R Us 108, 109

Computex 302

Compuview Products Inc 67

Concord Comp Components 360

Consumer Computers 108, 109

Corvus Systems 73

Cover Craft 295

CPI 119

CPU Shop, The 363

Cromemco 1, 2

Crystal Computer 79

Custom Business Comp 356

Custom Peripherals 350

Cybernetics Inc 98

Data Discount Center 327

Datamax 62

Data Safe Products 24

Datasouth Computer Corp 333

Decision Master 105

Delta Products 191

Denver Software Co, The 171

DG Electronics 245

Diablo (Div of Xerox) 207

Digiac Corp 112

Digital Graphic Systems 254

Digital Marketing 243

Digital Pathways 133

Digital Research 25

Digital Research Computers 351

DIP Inc 217

Discount Sftw Grp, The 312

Disk Supply Co 248

DMA 332

Dual System Control Corp 218

DWP277

Dymarc Industries 289

Dynabyte C III

Dynacomp Inc 263

Inquiry No.

Page No.

47 Ecosoft 88

104 Edmund Scientific 178

" Electravalue Industrial 356

132 Electronic Control Tech 212

279 Electronic Equip Unltd 350

191 Electronic Specialists 279

213 Ellis Computing 291

94 Epson America Inc 165

69 Escon 128

20 ESP Comp Resources Inc 26

241 Essex Publishing Co 324

80 Exatron Inc 143

240 Faircom 322

198 Farnsworth Comp Center 283

260 Feith Software 275

51 John Fluke Mfg Co 97

321 Fordham 362

222 Frederick Comp Prod 297

* Game-A-Tron 352

79 General DataComm Ind 139

78 GNT Automatic Inc 138

140 Godbout Electronics 220, 221

10 Mark Gordon Computers 14

122 H & EComputronics 196, 197

165 H & EComputronics 253

304 Hanley Engineering 355

288 Harris Corp 352

184 Hayden Book Co Inc 271

34 Hayes Microcomp Prod Inc 61

207 Hayes Microcomp Prod Inc 287

121 Hazeltine Corp 195

13 Heath Company 17 74 Hewlett-Packard 135

33 High Technology Inc 60

316 Hobby world Electronics 358

40 Houston Instruments 71

41 Houston Instruments 71 284 IDM 350

* Illinois Comp Mart Inc 275 68 IMS International 127

14 Info Unltd Software 18 177 Innovative Sftw Appl 265

66 Integral Data Sys 121

169 Integrand 256

29 Intel 53

201 Intelligent Control Sys 285

151 International Microsystems 235

56 Intertec Data Systems 103

204 Ipex Int'l Inc 286

5 Ithaca Intersystems 8

6 Ithaca Intersystems 9 281 J & S Computers 350

330 Jade Computer Prod372, 373

328 Jameco Electronics 368, 369

233 JDR MICRODEVICES314

322 JR Inventory Control 362 179 KeeSoft 266

" Konan Corp 145

164 Lax Computer Products 252

235 Lax Computer Products 316

* Leading Edge Products 91

76 Lifeboat 125 145 Lifeboat 228 174 Lifeboat 260

* Lifelines 131 306 Lin mar 356

149 Livermore Data Sys Inc 232

203 LNW Research 285

71 Lobo Drives Int'l 136

77 Lobo Drives Int'l 137 46 Lomas Data Prod 84

163 McClintock Corp 252

277 Macrotronics Inc 350

187 Mann, Charles & Assoc 274

194 Marymac Industries Inc 281 200 Mattel Inc 284

183 MBC Systems Inc 270

* Meas Sys & Controls 29, 129 255 Meta Technologies Corp 336 212 MFJ Enterprises Inc 290

85 Micro Age Computer Store 151

195 Micro Architect 281

215 Micro Business World 291

* Micro Comp Discount Co 304 245 Micro Comp Store, The 329

96 Micro Data Base Sys 169

155 Micro Management Sys 241

26 Micro Mikes 49

Inquiry No.

Page No.

182

265

237

67

107

106

90

249

242

173

175

257

161

324

53

196

324

325

62

15

89

185

220

70

183 186 136 95

52 330

60 216 230 126 139 228

197 83 84

171

285 264 247 289 294 315 3 300 305 11 25 109 110 111 112 113 114 133 22 160 167 178 93 73 322 323 253 270 239 267 246 290 283 229 329 142 261 105 154 81 258

Micro Pro International 269

Micro Products Unltd 275

Micro Works, The 319

MicroAce 123

MicroByte 183

Microcomp Tech Inc 180, 181

MicroDaSys 161

Microhouse 331

Micromail 325

MICROMATE ELECT 260

MicropolisCorp 261

MicroTech Exports 275

Microware Sys Corp 250

Mikos 364

Miller Microcomputer Serv 100

Mini Computer Suppliers 281

Mini Micro Mart 380

Mini Micro Mart 381

Morrow Designs 113

Mountain Computer Inc 19

mpi 159

MT MicroSYSTEMS83

MTI Inc 272

Mt. View Press 295

MUSYS 130

Multi Business Comp Sys 270

NCC '81 273

NCE Supply Corp 216

NEECO 167

Netronics 303, 305

Noesis Computing Co 317

NRI Schools 193

Ohio Data Products Corp 82

Ohio Scientific Instr C IV

OK Machine & Tool 111

OlympicSalesCo 293

Omega Micro Computers 310

Omega Research 202

Omega Sales Co 219

Omikron 306

onComputing 225

Optimal Technology 283

Orange Micro 147

Osborne/McGraw-Hill 148, 149

OSM Computer 258

Owens Associates 28, 308, 309

P & S Electronics 352

Pace Age Tech 275

Pacific Exchanges 330

Pacific Exchanges 352

Page Digital 353

Pan American Elec 358

PCD Systems Inc 6

PC Newsletter, The 354

Pelican Programs 356

Percom Data 15

Percom Data 35

Percom Data 185

Percom Data 185

Percom Data 185

Percom Data 185

Percom Data 185

Percom Data 185

Personal Micro Computers 213

Personal Software 31

Phase One Systems 249

Pickles & Trout 254

pk systems inc 266

Potomac Micro Magic 164

Power One Inc 134

Priority One 376, 377

Priority One 378, 379

Professional Business Sftw 334

Professional Comp Store 277

Prometheus Products Inc 321

Purchasing Agent, The 277

Purchasing Agent, The 330

Purchasing Agent, The 352

Q Systems 350

QT Computer Systems 310

QT Computer Systems 370, 371

Qantex 223

Quality Computer Parts 275

Quality Software 179

Quasar Data Products 239

Quest 345

Quintrex Inc 275

R & B Computer Systems 12

Inquiry No.

Page No.

211 209

45

119 108 252 159 21 219 103 271 190 2 226

180

295 259 234

54

88 134 102 232 153 205 144 328 129 7

92 208 218

28 325

172 225

30 287 152 276 4 254

50 189 301 309 170 266 143

24 327 146 269

87

31 297 135 158

86 317

23 75 125 193 224 308 65 286 280 314 101

Racet Computes 289

Radgo Sales Co 289

Radio Shack 81

Rainbow Computing 258

RCA Solid State 192

REI Sales Co 184

RNB Enterprises 334

Rochester Data 299

S & M Systems 30

S-100 Inc 295

Howard W SamsCo 177

SC Digital 277

Scientific Eng Labs 279

Scion Corp 5

SciTronics Inc 299

Scottsdale Systems 144

Seattle Computer Prod 267

Shugart 7

Silverman Assoc 291

Sinclair Research 87

Skyles Electr Works 354

Sluder 275

Small Business Appl 315

Snapp Inc 101

Softech Microsystems 157

Softech Microsystems 214

Software Toolworks, The 176

Solid State Sales 313

Sorcim 238

Sorrento Valley Assoc 286

Southern Semiconductors 227

Southwest Tech Prod Corp Cll

Spectrum Software 205

SSM 11

Standard & Poors 163

Street Electronics 287

SubLOGIC 293

Summagraphics 52

Sunny Int'l 364

SuperSoft 10, 92, 93, 102, 311

Super Star Int'l Corp 155

Sybex 107

Synchro Sound 75, 292

Systems Plus 259

Tarbell Electronics 299

Tech Sys Consultants (TSC) 55

Technical Innovations 352

TecMar Inc 237

Terminal Data Sys 350

Texas Instruments 27

3G Company 335

3M Company 95

Thunderware 276

Mitchell E Timin Eng Co 354

TPA 356

TNW Corp 256

Toolsmith, The 277

TransNET 226

TSE/Hardside 172

TSE/Hardside 173

United Software of Am 140, 141

Urban Software Corp 34

US Micro Sales 366, 367

US Robotics 229

Vamp 277

VAN DATA 104

Vector Graphics 57

Vertical Data 354

VictorData 215

Videx 247

Vista Computer Co 153

Vista Computer Co 359

Westico Inc 188, 189

White Computer Sys 33

Whitesmith's Ltd 99

CJ Wigglesworth Software 200

Wild Hare Comp Sys 280

John Wiley & Sons 297

Wintek Corp 356

Winterhalter & Assoc 120

Winchendon Group, The 352

Worldwide Electronics 350

WW Component Supply Inc 357

Xerox 175

XPS Inc 277

Zobex 257

To get further information on the products advertised in BYTE, fill out the reader service card with your name and address. Then circle the appropriate numbers for the advertisers you select from the list. Add a 15<ent stamp to the card, then drop it in the mail. Not only do you gain information, but our advertisers are encouraged to use the marketplace provided by BYTE. This helps us bring you a bigger BYTE. The index is provided as an additional service by the publisher, who assumes no liability for errors or omissions. 'Correspond directly wjth company.

384

March 1981 © BYTE Publications Inc

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No one has a broader line of micro-based business computers than Dynabyte. Memory to 400KB. Mini-floppies, eight inch floppies, Winchesters and cartridge module hard disks; capacity from 630KB to 96MB. Satisfy all your clients' needs with Dynabyte. Start small, expand the system as computing needs grow, with modular add-ons from Dynabyte. With complete software and hardware compatibility across the entire line.

But expandable memory and the broad range of storage capacities are only part of the DYNABYTE DIFFERENCE. How about multiple terminals? Foreground/background? With Dynabyte you can have up to eight partitions, driven from up to eight terminals. And each terminal can have its own spooler; or all can share a system spooler. How about up to sixteen printers, and they don't require any partition space either. The DYNABYTE DIFFERENCE.

Our operating systems are the standard CP/M™ for single user sites and Dynabyte-enhanced MP/M™ for multiple user sites. As a seller of business systems you already have a whole library of applications

software. So to help protect your software investment we offer COBOL and BASIC and FORTRAN and PASCAL and PL/1. ' \

Or you can use BUSINESS MANAGER!" Dynabyte's fully integrated accounting system. Menu driven, well documented, easy to install; it fits the needs of most wholesalers and distributors as is.

With no direct sales outlets, we are totally committed to our resellers. We don't compete with them. We support them with full service others only promise. Another DYNABYTE DIFFERENCE.

If you're tired of only promises from your computer suppliers; if you're losing sales because of price or limited storage capacity, or lack of modular expansion capability, call Dynabyte. Ask about the DYNABYTE DIFFERENCE. Ask about our advertising and lead referral programs. Ask about our warranty program.'You'll be surprised.

Call our toll-free hotline: (800) 227-8300.' In California (415) 329-8021. Dynabyte, 115 Independence Drive, Menlo Park, California 94025. Call or write today for the DYNABYTE. DIFFERENCE. ,'

CpSeJ*Man,

CP/M

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Digital

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Ohio Scientific: The leader in Winchester based microcomputers.

Ohio Scientific produced the first large capacity fixed media hard disk (Winchester) based microcomputers in 1977. Since then we have shipped more of these systems than the rest of the microcomputer industry combined.

Family Features

All standard C3 features including:

• 3-processor CPU with 6502, Z80 and 6800

• .7MIPS6502A •48K static RAM

• Dual 8" floppies

• Free standing rack for direct expansion capabilities

• 17-slot OSI 48 line BUS architecture for large system expansion

• Directly accepts up to 8 users with currently available memory boards, more with higher density boards in the future

• Directly expandable for use as Network data bases

• Slide-mounted subassemblies, removable side panels and locking rear door for easy expansions and service.

C3A

The floppy only rack based C3 for users who anticipate expansion to hard disk, multi-user and/or networking in the future. Under $7000.

C3B

The world's most powerful microcomputer (when GT equipped). Features the highly advanced and extensively field proven OKIDATA 3306 Winchester disk.

Features

• System boots from floppies or hard disk on power up

• 74 megabytes end user workspace under OS-65U, 80 megabytes unformatted

• Ultra-high performance disk 74 millisec worst case access 38 millisec average

10 millisec access on cylinder (215K user workspace) 8 megabits per second transfer rate

• Simple on/off disk operation with elaborate internal protection from improper temperature, line voltage and controller failures

• Features spindle brake and designated head landing areas for much longer operational life than the newer low-cost Winchesters

• Highly advanced OS-65U operating system: Multiple level pass word security Multiple operating systems on disk

Ultra-high speed "FIND" command for high speed string searches (Associative Access)

Upward compatible with multi-user and network systems with full file, peripheral and communications arbitration between users

• Available factory configured for up to 8 users and network data base operation

• Expandable to CP/M operation by adding 4K (CM-2 memory) Under $14,000

C3C

A medium performance Winchester disk based system

which provides the ideal cost/performance ratio in typical

small business applications. The C3-C uses the Shugart

SA4008 29 megabyte Winchester disk.

Performance specifications, hardware configuration and

software is identical to the C3-B with the following

exceptions:

• 23 megabytes of end user workspace under OS-65U

• 29 megabytes unformatted capacity

• Medium performance Winchester 240 millisec worst case access 87 millisec average access

10 millisec access on cylinder (110K user workspace)

• Simple on/off disk operation Under $11,000

Ohio Scientific has a new OEM program that is easy to start with, and provides generous discounts for quantity purchases.

For literature and the name of your local dealer, CALL 1-800-321-6850 TOLL FREE.

1333 SOUTH CHILLICOTHE ROAD AURORA, OH 44202 • [21 6] 831-5600

Circle 355 on inquiry card.