Byte Magazine Volume 04 Number 09 - Homebrewing

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If you have a problem that can be solved by a computer—we have a systems solution.

* Two central processors with maximum RAM capacities of 56K and 384 K bytes

* Three types of disk drives with capacities of 175K, 1.2M and 16M bytes

* Two dot matrix printers with 80 and 132 line capacity

A Selectric typewriter interface and a daisy wheel printer

Match these to your exact need, add one or more of our intelligent terminals and put togethera system from one source with guaranteed compatibility in both software and hardware.

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Naturally, it's from Cromemco.

It's a reality. In Cromemco's newModel Z-2H you get all of the aboveand even more. With Cromemco youget it all.

In this new Model Z-2H you getnot only a large-storage Winchesterhard disk drive but also two floppydisk drives. In the hard disk drive youget unprecedented storage capacityat this price—11 megabytes unfor-matted.

You get speed—both in the 4 MHzZ80A microprocessor and in the fast64K RAM which has a chip accesstime of only 150 nanoseconds. Youget speed in the computer minimuminstruction execution time of 1 micro-second. You get speed in the harddisk transfer rate of 5.6 megabits/sec.

EXPANDABILITY

You get expandability, too. Thehigh-speed RAM can be expanded to512 kilobytes if you wish.

And the computer has a full 12-slotcard cage you can use for additionalRAM and interface cards.

BROADEST SOFTWARE SUPPORT

With the Z-2H you also get thebroadest software support in the

microcomputer field. Software Cro-memco is known for. Software likethis:

• Extended BASIC

• FORTRAN IV

• RATFOR (RATional FORtran)

• COBOL

• Z80 Macro Assembler

• Word Processing System

• Data Base Management

with more coming all the time.

SMALL, RUGGED, RELIABLE

With all its features the new Z-2H,including its hard disk drive, is stillhoused in just one small cabinet.

Included in that cabinet, too, isCromemcoruggednessand reliability.Cromemco is time-proved. Ourequipment is a survey winner forreliability. Of course, there's Cro-memco's all-metal cabinet. Rugged,solid. And, there's the heavy-dutypower supply (30A @ 8V, 15A @+ 18 V, and 15A @ -18V) for cir-cuitry you'll sooner or later want toplug into those free card slots.

CALL NOW

With its high performance and lowprice you KNOW this new Z-2H isgoing to be a smash. Look into itright now. Contact your Cromemcocomputer store and get our salesliterature. Find out when you cansee it. Many dealers will be showingthe Z-2H soon — and you'll want tobe there when they do.

ra

Hard disk drive at lower left can be inter-changed just by sliding out and disconnectingplug. Seven free card slots are available.Z-2H includes printer interface card.

Cromemco

PRESENT CROMEMCO USERS

We've kept you in mind, too. Askabout the new Model HDD DiskDrive which can combine with yourpresent Cromemco computer to giveyou up to 22 megabytes of diskstorage.

Circle 80 on inquiry card.

•^^^J 280 BERNARDO AVE., MOUNTAIN VIEW, CA 94040

^^* Tomorrow's computers now

(415)964-7400

BYTE September 1979

LatchedOutputs

4 MHzCrystal Clock

On Card

Voltage

Regulation

ParallelI/O Port #1

\

ParallelI/O Port #2

/

ParallelI/O Port #3

\

RS-232 orCurrent LoopI/O Port #4

8KROMCapacity

IK RAM

Standard Bus

for SystemExpandability

ProgrammableBaud RateUARTwith

Interval Timers

4 MHz Z-80A

Completely BufferedBus Interface

The single card computer

with the featuresthat help you in real life

COMPLETE COMPUTER

In this advanced card you get a pro-fessional quality computer that meetstoday's engineering needs. And it's onethat's complete. It lets you be up andrunning fast. All you need is a powersupply and your ROM software.

The computer itself is super. Fast4 MHz operation. Capacity for 8K bytesof ROM (uses 2716 PROMs which canbe programmed by our new 32K BYTE-SAVER® PROM card). There's also 1K ofon-board static RAM. Further, you getstraightforward interfacing through anRS-232 serial interface with ultra-fastspeed of up to 76,800 baud — softwareprogrammable.

Other features include 24 bits of bi-directional parallel I/O and five on-board programmable timers.

Add to that vectored interrupts.

ENORMOUS EXPANDABILITY

Besides all these features the Cro-memco single card computer gives youenormous expandability if you ever needit. And it's easy to expand. First, youcan expand with the new Cromemco32K BYTESAVER PROM card mentionedabove. Then there's Cromemco's broadline of S100-bus-compatible memoryand I/O interface cards. Cards with fea-tures such as relay interface, analoginterface, graphics interface, opto-isolator input, and A/D and D/A con-version. RAM and ROM cards, too.

Card Cage 32K BYTESAVER PROM card

EASY TO USE

Another convenience that makes theModel SCC computer easy to use is ourZ-80 monitor and 3K Control BASIC (intwo ROMs). With this optional softwareyou're ready to go. The monitor givesyou 12 commands. The BASIC, with 36commands/functions, will directly ac-cess I/O ports and memory locations —and call machine language subroutines.

Finally, to simplify things to the ulti-mate, we even have convenient cardcages. Rugged card cages. They holdcards firmly. No jiggling out of sockets.

AVAILABLE NOW/LOW PRICE

The Cromemco Model SCC is avail-able now at a low price of only $450factory assembled ($395 kit).

So act today. Get this high-capabilitycomputer working for you right away.

G

Cromemco

incorporatedSpecialists in computers and peripherals280 BERNARDO AVE., MOUNTAIN VIEW, CA 94040

(415) 964-7400

2 BYTE September 1979

Circle 80 on inquiry card.

In The Cue we

BITI September 1979Volume 4, Number 9

Foreground

1020347096118130

62

84

160

182

196

JOYSTICK INTERFACES by Steve CiarciaAn interface for every purpose

INTRODUCTION TO MULTIPROGRAMMING by Mark DahmkeSome basic concepts

INTERFACE A CHESSBOARD TO YOUR KIM-1 by Jeff TeetersPlay chess with a computer as easily as with a human opponent

A LOW-SPEED ANALOG-TO-DIGITAL CONVERTER by Richard C HallgrenPerform real-time data analysis

THE NATURE OF ROBOTS, Part 4 by William T PowersA simple, human experiment

INEXPENSIVE, OPTICAL PAPER-TAPE READER by Brian A HarronA manual paper-tape reader with no moving parts

A MODEL OF THE BRAIN FOR ROBOT CONTROL, Part 4 by James AlbusDecision-making procedures

Background

page JO

SOME MUSINGS ON HARDWARE DESIGN by Clayton EllisSimple design techniques

SOLDERING TECHNIQUES by William TrimmerA picture essay

HANDY PULSER by Bob ChrispA simple, circuit-debugging tool

THE AMSAT-GOLEM-80 by Joe Kasser

A modular and inexpensive S-100 computer system

ADD SOME CONTROL TO YOUR COMPUTER by Ken BarbierLet your computer influence the outside world

Nucleus

Editorial: The Rationale of

Yet Another Homebrew System 6Programming Quickies 58,126Unclassified Ads 61BYTE's Bits 80Technical Forum 82Clubs and Newsletters 92BYTE News 115

Book Reviews 122,152Letters 150Languages Forum 164Event Queue 176What's New? 214Reader Service 256BOMB 256

page 34

Cover Art: Fantasy on Homebrewing by Robert Tinney.

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 subscriptionsto above address: phone (603) 924-7217. Address subscriptions, change of address, USPS Form 3579, and fulfillment questions to BYTE Subscriptions, PO Box 590, MartinsvilleNJ 08836. Second class postage paid at Peterborough NH 03458 and at additional mailing offices—USPS Publication No. 102410 (ISSN 0360-5280). Subscriptions are $18 for oneyear, $32 for two years, and $46 for three years in the USA and its possessions. In Canada and Mexico, $20 for one year, $36 for two years, $52 for three years. $32 for one year airdelivery to Europe. $32 surface delivery elsewhere. Air delivery to selected areas at additional rates upon request. Single copy price is $2 in the USA and its possessions, $2.40 inCanada and Mexico, $3.50 in Europe, and $4 elsewhere. Foreign subscriptions and sales should be remitted in United States funds drawn on a US bank. Printed in United States ofAmerica.

Address all editorial correspondence to the editor at the above address. Unacceptable manuscripts will be returned if accompanied by sufficient first class postage. Notresponsible for lost manuscripts or photos. Opinions expressed by the authors are not necessarily those of BYTE. Entire contents copyright © 1979 by BYTE Publications Inc. Allrights reserved.

BYTE's is available in microform from University Microfilms International. 300 N Zeeb Rd, Dept PR. Ann Arbor Ml 48106 USA or 18 Bedford Row, Dept PR, London WC1R 4EJENGLAND.

Subscription WATS Line: (800) 258-5485

Office hours: Mon-Thur 8:30 AM - 4:30 PMFriday 8:30 AM - Noon

September 1979 © BYTE Publications Inc 3

About the Cover

On this issue's cover, RobertTinney has created a "fantasy onhomebrewing." In the middle ofa sylvan glade, we see the formof a computer being sculpted bysome homebrewer. A couple ofhumanoid forest denizens lookon with wonder, perhaps hopingto get a glimpse of our home-brewer on his return to the work-place.

Building a joystick in-terface for your computersystem adds a newphysical input dimension.There are as many dif-ferent ways to interface ajoystick as there are ap-plications. Steve Ciarciadiscusses several widelyvarying ways to designJoystick Interfaces.Page 10

The idea of having amicrocomputer work in amultiprogramming en-vironment is becoming areality. Already there areseveral multiprogram-ming systems on themarket. Mark Dahmkeprovides an Introductionto Multiprogramming sowe can understand howthese systems operate.Page 20

If you enjoy playingchess against your com-puter, but dislike typingin the moves in abstractnotation, you will be in-terested in a method ofallowing the computer todetect moves made on areal chessboard. JeffTeeters devised such amethod and now tells ushow he did it in Interfacea Chessboard to YourKIM-1.

Page 34

Some Musings OnHardware Design by

Clayton Ellis providesreaders with backgroundinformation on pickingintegrated circuits andusing them in homebrewwork.

Page 62

Although there aremany applications wherea high-speed analog-to-digital converter isnecessary, many conver-sion applications canmake do with a slowerconversion. Richard CHallgren has built ALow-Speed Analog-to-Digital Converter for theApple II which he uses asa real-time data analyzer.Page 70

When constructingelectronic equipment, it isimperative that goodSoldering Techniques aredeveloped. William Trim-mer presents a photoessay of good solderingpractices and several ex-amples of unwantedtechniques.

Page 84

William T Powersbrings his discussion ofThe Nature of Robots toa close by applying thepreviously-discussedtechniques and theories ina simple experiment witha human subject.Page 96

The search for the in-expensive paper-tapereader continues as Brian

A Harron describes anInexpensive, OpticalPaper-Tape Reader.

Page 118

James Albus considersthe mechanisms of choicein his closing articleabout A Model of theBrain for RobotControl.

Page 130

A Handy Pulser can

prove to be very usefulwhen testing a digital cir-cuit. Bob Chrisp shareswith us his version of auseful pulse generator.Page 160

In The AMSAT-GOLEM-80, Joe Kassershows how your com-puter club (or any othergroup of experimenters)can economically buildan S-100 microcomputer.The system is modularand expandable.Page 182

Performing simple con-trol functions with yourcomputer can be easy.Ken Barbier describeshow to Add Some Con-trol to Your Computer.Page 196

Publishers

Virginia LondonerGordon R WilliamsonAssociate PublisherJohn E HayesAssistantJill E Calllhan

Editorial Director

Carl T Helmers JrExecutive EditorChristopher P MorganEditor In ChiefRaymond G A CoteSenior EditorBlaise W LlffickEditor

Richard S ShufordAssistant EditorsKent RichardBob BraisledEditorial AssistantsGale BrittonFaith FerryNew Products EditorClubs, NewslettersLaura A HansonDraftingJon Swanson

Production Director

Nancy EstleProduction Editors

David William Hayward

Ann Graves

Faith Hanson

Warren Williamson

Robin M Moss

Anthony J Lockwood

Art Director

Ellen Bingham

Production Art

Wai Chiu LI

Christine Dixon

Holly Carmen LaBosslere

Deborah Porter

Typographers

Cheryl A HurdDebe L WheelerSherry McCarthyKathy BeckerPhotostat TechnicianTully Londner

Advertising Director

Patricia E BurgessAssistantsRuth M WalshMarion GagnonJanet AmesEileen KindlAdv/Prod CoordinatorThomas HarveyAdvertising BillingNoreen BardsleyDon Bardsley

Circulation Manager

Gregory SpltzfadenAssistantsPamela R HeaslipAgnes E PerryMelanle BertoniBarbara EllisDealer SalesGinnie F BoudrieauAnne M BaldwinReceptionistJacqueline Earnshaw

National AdvertisingSales Representatives:

Hajar Associates Inc

East

280 Hillside Av

Needham Heights MA 02194

(617) 444-3946

521 Fifth Av

New York NY 10017

(212) 682-5844

Midwest

664 N Michigan Av

Suite 1010

Chicago IL 60611

(312)337-8008

West, Southwest

1000 Elwell Ct

Suite 227

Palo Alto CA 94303

(415) 964-0706/(714) 540-3554

Traffic Department

Mark SandagataThomas Yanni

Comptroller

Kevin MaguireAssistant

Mary E Fluhr

Officers of McGraw-HillPublications Company: GordonL. Jones, President; Group VicePresidents: Daniel A. McMillan,James E. Boddorf; Senior VicePresidents: Russell F. Anderson;Ralph R. Schulz, Editorial; VicePresidents: James E. Hackett,Controller; Thomas H. King,Manufacturing; Robert L.Leyburn, Circulation; John W.Patten, Sales; Edward E.Schlrmer, International.

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

September 1979 © BYTE Publications Inc

*****

I've seen Lanier, Vydec,

Xerox, Olivetti, and Wang.

I've chosen WORDSMITH

from MICRO DIVERSIONS.

Congressman Charlie Rose

Chairman, Policy Group

on Information and

Computers

LOORDsrrjftb

TEXT EDITOR

Yes, I'd like to learn more about Wordsmith.™ Send me your information packet.Name.

Company

Address.

City

State

Zip

Micro Diversions, Inc.8455-D Tyco Road,Vienna, Virginia 22180(703) 827-0888

BYTE September 1979 5

Look for

in personal

computer systems

made by these

companies.

Editorial

Altos Computer Systems

2378-B Walsh AvenueSanta Clara. CA 95050

Apple Computer

10260 Bandley Dr.Cupertino, CA 95014

Digital Microsystems Inc.

(Formerly Digital Systems)4448 Piedmont Ave.Oakland, CA 94611

Imsai Mfg. Corporation

14860 Wicks Blvd.

San Leandro, CA 94577

Industrial Micro Systems

633 West Katella, Suite LOrange, CA 92667

North Star Computer

2547 9th StreetBerkeley. CA 94710

Percom Data

318 BarnesGarland, TX 75042

Polymorphic Systems

460 Ward Dr.

Santa Barbara, CA 93111

Problem Solver Systems

20834 Lassen StreetChatsworth, CA 91311

Processor Applications Limited

2801 E. Valley View AvenueWestCovina, CA91792

SD Sales

3401 W. KingsleyGarland, TX 75040

Smoke Signal Broadcasting

6304 YuccaHollywood, CA 90028

Technico Inc.

9130 Red Branch RoadColumbia, MD 21045

Texas Electronic Instruments

5636 EtheridgeHouston, TX 77087

Thinker Toys

1201 10th StreetBerkeley, CA 94710

Vista Computer Company

2807 Oregon CourtTorrance, CA 90503

Shugart

6 September 1979 © BYTE Publications lnc

The Rationale ofYet Another Homebrew System

by Carl Helmers

In this issue of BYTE, we are placing a special emphasis on the homebrewingof computers: the craft of assembling the hardware and software of a systemfrom standard components in nonstandard ways. This month's editorial pro-vides a continuation of notes begun in July on the design and assembly of mynew homebrew 6809 system. In this editorial, we complete the final details ofthe physical layout and power supplies of the system, as well as the overalldesign of the system. We shall also begin a discussion of the actual processorcard. Future installments in this series on homebrew, general purpose, com-puter hardware will record details of the system beyond this article's goal ofdefining a backplane bus structure.

As noted earlier ("Editorial," June 1979 BYTE, page 6), the intent of thisexercise is to develop a specialized controller node for a loosely coupled systemof processors involved with musical applications. The multiple processors ini-tially contemplated were a Pascal-oriented, large personal computer and anALF products model AD-8 music synthesizer with its 6502 used for house-keeping. In addition to this coordinating task, the 6809 would provide a cen-tral point for the connection of keyboards, displays and other hardware re-quired by musical applications.

But ideas change and evolve. Since the 1st installments were written, planshave become slightly more grandiose with my recent acquisition of a NewEngland Digital "Synclavier" music synthesizer and its associated Able/60minicomputer. Located in Norwich VT, New England Digital is a combinedspin-off of the music and electrical engineering departments of DartmouthCollege across the Connecticut river in NH. The computer for the music syn-thesizer employs the XPL language as its high-level user interaction. The NewEngland Digital version of XPL is augmented by a floating-point data type.With the exception of an adaptation of UCSD Pascal, which is expected to beavailable soon, all systems software is written in XPL, including what isdescribed as a 3-pass optimizing XPL compiler.

[XPL is the language described in the book A Compiler Generator, byMcKeeman, Wortman, et al, published circa 1968. The commonly usedmicrocomputer language PL/M, 1st designed and implemented by GaryKildall, is very similar to XPL in syntax and semantics. XPL is a simple subsetof PL/I, with data types restricted to character and integer forms.]

At this point, I now have a need for multiple processor communicationsbeyond the level of 1 large machine (a Western Digital P-engine) driving asmart peripheral through a serial communications link. The smart peripheralwill still handle specialized details like the parallel interface to the older syn-thesizer and the eventual interface to an electronically controlled player piano.See photo notes on pages 8 and 9, text continued on page 202

My Shugart

followed me li

*

u

\

«

IX

i

"After working all day with the computer atwork, it's a kick to get down to Basic at home. Andone thing that makes it more fun is my Shugartminifloppy™- We use Shugart drives at work, sowhen I Pought my own system I made sure it had aminifloppy drive,

"Why? Shugart invented the minifloppy. Theguys who designed our system at work tell me thatShugart is the leader in floppy design and hasmore drives in use than any other manufacturer. IfShugart drives are reliable enough for hard-workingbusiness computers, they've got to be a goodvalue for my home system.

"When I'm working on my programs late atnight, I can't wait for cassette storage. Myminifloppy gives me fast random access and data

transfer. The little minidiskettes store plenty ofdata and file easily too.

"I made the right decision when I bought asystem with the minifloppy. When you lay out yourown hard-earned cash, you want reliability andperformance. Do what I did. Get a system with theminifloppy."

If it isn't Shugart,it isn't minifloppy.

*A Shugart

435 Oakmead Parkway. Sunnyvale, California 94086

See opposite page for list of manufacturers featuring Shugart's minifloppy in their systems.

TM minifloppy is a registered trademark ot Shugart Associates

BYTE September 1979

Hardware Basis...

These photographs depict some furdetails of the physical hardware of thenew homebrew 6809 computer system. Asnoted earlier, Vector Electronic Co com-ponents were used for the assembly of abackplane. Photographs 1 through 5 showvarious aspects of the new design'spackaging.

Photo 1: The new computer system's finalphysical mounting basis is a mahogonybox with guide blocks for the backplaneassembly. Power supplies are locatedunderneath the box. Power for the com-puter and accessories will be controlled bythe standard, household wall switchmounted on the side of the box. Powerconnections to the backplane power buseswill pass through a hole underneath thebackplane in this photo. The hole pro-vides an exit path for the flow of hot airfrom the power supplies.

Individual boards of the system pluginto the backplane from the top as shownhere. The backplane assembly slides intothe grooves of the 2 guide blocks. Theseblocks are bolted to the top of the boxusing Vi-20 machine-screws and threadedinserts. The grooves for the backplaneboard were cut l/16th of an inch widewith a router and edge guide. The wood-shop tools required to fabricate this caseincluded a table saw, electric hand drill,drill press, router, belt sander, sabre saw,and the usual collection of hand tools.

Photo 2: The power supply modules areattached to 2 wooden brackets which arescrewed into the main box by means ofVi-20 machine-screw threaded inserts.The power supply modules are mountedon the brackets using §8-32 threaded in-serts. Ordinary brass finish door stopsserve as legs to keep the assembly off thetable top, thus allowing natural convec-tion to cool the power supply modules.

No attempt is made to calculate heatingfactors. The inverted cup shape of the boxseems like an excellent trap for heat,however, the large hole beneath thebackplane assembly at the top of the boxprovides a relatively low-impedanceoutlet for the heated air from below. If thetemperatures observed under load areexcessive, then a fix will be necessary. In acommercial or industrial engineeringsituation where production of a product iscontemplated, this "patch up after pro-blems" strategy is not the recommendedpractice due to the possibilities of costlyerrors, but for one of a kind products in anoncommercial and highly experimentalcontext, it is certainly acceptable and caneconomize on time.

Photo 3: (a) Brass machine-screw insertsto provide metal to wood fastening in the

(1)

(2)

(3a)

8 September 1979 © BYTE Publications Inc

(5a)

(5b)

assembly of the computer housing. Theseparticular parts were purchased from theBrookstone Co Peterborough NH.

(b) When inserting the machine-screwfasteners into hardwood, better resultswere obtained when the hole drilled in thewood was l/64th of an inch larger thanthe recommended size in the instructions.A short section of the machine-screw to beused, together with a hex nut, provide atool for driving the insert as shown in thispicture. When using the §8-32 inserts inhardwood, a slightly larger hole than sug-gested in the instructions is a necessity.Unless the extra clearance is given, thetorque on the §8-32 bolt used in drivingthe insert will cause the insert to twistapart after 1 or 2 uses.

Photo 4: The backplane is the first and themost tiresome wiring involved with

assembly of a small computer. Its definiHon is provided by the simple instruc-tions:

FOR each free socket, pin BY NUMBEROF each socket,

CONNECT that pin to the same pinof the next socket in the backplane!

The backplane assembly loas describedin the notes of the July 1979 BYTE, page194. This photo shows the finishedbackplane after all wiring and installationof bypass capacitors has been completed.

Photo 5: The wiring of the backplane, aswell as the rest of this computer, was donewith the Vector Electronic Co's "slit-N-xorap" technique. An electric eraser wasused to motorize the connections, with anadapter custom-made on a small lathe. It is

recommended that motorized wiring beemployed with the "slit-N-wrap" tech-nique. In previous experimental elec-tronics built with this technique, relia-bility problems were encountered withmanual termination of the wires to wire-wrap socket posts. Motorized wrappingwith this tool provides a uniform andhigher force for stripping the insulationoff the wire.

At (a) is the adapter: a hollow tubemade from 2 junk box spacers, a §10-32bolt with a hole drilled through it, a brassunion between the 2 spacers, and a largebrass adapter to which a §10-32 nut issoldered. (This latter kludge is what hap-pens when one makes an adapter on aSunday afternoon and a §10-32 tap is notavailable!) At (b) the completed adapter ismounted in the Bruning Electric Eraser ina typical use situation.

September 1979 © BYTE Publications Inc 9

Gispcis's Circuit Bella*

Copyright © 1979 by StevenA Ciarcia. All rights reserved.

Joystick Interfaces

Steve Ciarcia

POB 582

Glastonbury CT 06033

Photo 1: A typical joystick with 4 potentiometers.

The thought that often comes tomind when the word joystick is men-tioned to a computer enthusiast is of aspacewar-type game. A photontorpedo is fired from an opponent'sstarship, and the thruster joystick isdeftly moved to reposition the craftout of its path. All of this occurswithout having to take your eyes offthe screen. Eye/hand coordination isalmost "instinctive." With a glance tothe upper right of the video screen,the joystick is tilted to the upper-rightcorner of its 360° range. This movesthe spacecraft toward that coor-dinate. Reverse thrust is accomplish-ed by moving the joystick in the op-posite direction, as though you arepulling back on the throttle of a real

craft. Such is the general experiencewith joysticks. However, the poten-tial use of these devices greatly ex-ceeds that of game playing.

A joystick, for those people whoare unfamiliar with one, is shown inphoto 1. It is an electromechanicaldevice with resistance outputs pro-portional to the X,Y displacement ofa central ball and lever. Photo 2illustrates the mechanical connectionsto the potentiometers.

When the stick is positioned in thecenter of its axes, the X and Y poten-tiometers show resistances in thecenter of their ranges. When the stickis tilted to the upper right, bothpotentiometers are at their full-resistance limit, while the opposite

Photo 2: Note how moving the stickmoves the gimbal arrangement, which inturn changes the settings of the poten-tiometers.

(lowest resistance) is true when in thelower-left position. The outputs ofthe 2 potentiometers accurately track,as if on an X,Y coordinate axis, theposition of the joystick. It should benoted that while it takes only 2 poten-tiometers to define 2-dimensionaltravel, most joysticks are manufac-tured with 4 potentiometers. This is aremnant of the days when joystickswere connected directly to the 4deflection-plates of a cathode raytube (video screen).

It is one thing to consider inter-facing a joystick to a computer, andquite another to do it. A joystick is amechanical X,Y positioning device.Even with proportional output resis-tances, an input interface must bedesigned to convert position from ananalog to a digital representationwhich can be used by the computer.A further consideration is the resolu-tion, or percent, of full-scale travelper bit sensitivity. Is the applicationso gross that center and full-scale arethe only points of interest, as in a

10 September 1979 © BYTE Publications Inc

ILL TO'

j - i F |]

~ ' ........mhiii'

'VLiJJ'

im'iilllltllllllUH"

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SYSTEM INCLUDES:

2 Siemens 8" Disk Drives1 Cabinet with Fan andPower Supply.

1 Tarbell Floppy Disk Inter-face, assembled & tested.1 CP/M Disk Operating Sys-tem.

1 Tarbell BASIC.All Cables and Connectors.

> Complete User Documenta-tion.

> Fully factory assembled andtested.

1 ; $1888.00

950 DOVLEN PLACE • SUITE B • CARSON, CALIFORNIA 90746(213) 538-4251 • (21 3) 538-2254

Circle 360 on inquiry card.

BYTE September 1979 11

2 JOYSTICK POTENTIOMETERS

J 1 !~7

^IN4728 ^,F /

T 3.9V ^ /

rh m „ 1/ iok

470

nsvi

C>B3

0>B2

Obi

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TO 4 LEASTSIGNIFICANTBITS OFINPUT PORT I

ICI

LM339

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Number TypeIC1 LM339

IC2 LM339

O87

OB6

OB5

C>B4

TO 4 MOSTSIGNIFICANTBITS OFINPUT PORT I

+ 5 V GND

3 12

3 12

"R«= APPROXIMATELY IOOOHMS

Figure 1: Low-resolution static interface. This interface is for 1 2-potentiometer joystick. For 4-potentiometer joysticks, build a secondcircuit like this one, and interface it to another input port. Note that if the comparator does not trigger at full-scale setting, a smallresistor may have to be added at Rx (marked with asterisk).

game control, or is the applicationone which requires fine control, suchas a cursor-positioning device in ahigh-resolution graphics system?

All joystick interfaces are notcreated equal. There is a trade-offbetween hardware and software. Thelower the resolution, the fewer theparts. The higher the resolution, thegreater the electrical complexity orthe software interaction with the in-terface. It is also important torecognize that computer systemswhich operate only in a high-levellanguage like BASIC cannot use aninterface design that requires anassembly language subroutine as anintegral component. In such instancesonly a static interface can be used.

Included in this presentation are 4interface designs which should covermost requirements, as well asdemonstrate the considerable dif-ferences between them. The 4 typesare:

• low-resolution static

• high-resolution fully statichardware

• software-driven pulse-widthmodulated

• high-resolution analog-to-digital

Low-Resolution Static Interface

First of all, static simply means thatthe interface hardware determines thepotentiometer position value and pre-sents it in constant, parallel digitalform to the computer. When theinterface is attached to any parallelinput port, this joystick value can beread with a single INPUT commandin BASIC. As far as the computer isconcerned, the value is fully static,and the computer reads whateverdata is there when the INPUT is ex-ecuted. The interface hardware hasthe responsibility of asynchronouslyupdating the digital value as the stickis moved.

Often the joystick is simply used toindicate relative direction andmagnitude. In a wheelchair, for in-stance, full linear control of speed

and direction would require ratherexpensive drive electronics. Mostchairs use simple relay contacts andprovide 2 or 3 selectable speeds. Ajoystick control built for this applica-tion would not have to have a resolu-tion of 8 bits, but could, in fact, suf-fice with 2. Figure 1 shows a low-resolution static output joystick inter-face suitable for use in thisapplication.

Each potentiometer is connected asa voltage divider between a referencevoltage source of 3.9 V and ground.The voltage output of each poten-tiometer is, in turn, fed to a 2-bit,parallel analog-to-digital converter.This type of converter uses 4 com-parators set for 25%, 50%, 75%, and100% of full scale. If a voltage, whenapplied, is less than 0.975 V, all com-parator outputs will be at 0 V. At 1.0V, corresponding to the joystick be-ing moved 25% of full scale, the leastsignificant bit (LSB) of the converterwill be a logic 1, while the other bitsare low. Similarly, at full input all

12 September 1979 © BYTE Publications Inc

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BYTE September 1979 13

comparators will be triggered, andbits 0 thru 3 will be logical Is.

Additional encoding logic can beadded to produce a true 2-bitrepresentation from the 4 compara-tors, but it is just as easy for a com-puter to interpret it directly. With a

4-bit connection as shown, used in aBASIC program, 25% of full scalewould be 1 decimal, 50% of full scalewould be 3 decimal, 75% of full scalewould be 7 decimal, and full scalewould be 15 decimal. It should beeasy to trigger any action by a coin-

cidence with these values. The realsignificance of this method is that thepotentiometer position is presentedstatically to the computer and re-quires no other interaction. Thismakes it ideal for direct use withBASIC.

5VA

1

50K

;o.i/iF

3 4

■<Z3 CLOCK

Al A2

Cext Q

ICI

74121

35ms

rext/cEXt

o

8-BIT Ri POSITION

BO Bl B2 B3

B4 B5 B6 B7

0 0 0 0

IC67404

7486

7400

O.I/uF

3 LOAD

7400

12

II

0 0 0 0

10

QA 0B Qc Qd

L0CK 2 '7C4995

A B C D

6 CLEAR

CLOCK O-

HTvJ COUNTIC5a fc>

+ 5VA

VR2 __ 4 50K ^pO.IMF

-<Z2 CLOCK

IC67404

13

12

II

0

QA QB Qc QDA B C D

A B C D

INPUT B | C7

INPUT A 7493

RO(I) R0(2)

A B C D

INPUT B ,C8

INPUT A 7493

RO(l) R0(2)

Al A2

Cext Q

IC2

74121

35ms

REXT/CEXT

8-BIT R-> POSITION

30 Bl B2 B3

B4 B5 B6 B7

0 0 0 0

IC67404

E*8

u. I3

47ft

7400

1I

10 i ^

13.. \g LOAD

"TTJJ IC3b)o^ f-^l _J/>~

O.I/iF

7400

13

II

0 0 0 0

0

QA Qb Qc Od

LOCK 2 £|g

A B C D

II CLEAR

CLOCK 0>-

6 COUNT

IC67404

12

13

12

II

10

Qa Ob Qc Qdlock 2 !£«B

A B C D

A B C D

INPUT B

ICI I

INPUTA ?493

ROU) RO(2)

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A B C D

INPUT B

I C 12

INPUTA ?493

RO(l) R0(2)

14 September 1979 © BYTE Publications Inc

High-Resolution Static Interface

It is quite possible that 2 bits ofresolution is not enough for yourapplication, but direct compatibilitywith a slow, high-level language isstill a requirement. Expanding theparallel comparator method willwork in theory, but you must realizethat a 4-bit analog-to-digital con-verter uses 15 comparators, and an8-bit, parallel analog-to-digital con-verter needs 255 comparators! Somuch for that method.

Realizing that the output of thejoystick is a variable resistance, wecan use this to advantage. This resis-tance can set the time constant of a

Number

Type

+ 5 V

GND

IC1

74121

14

7

IC2

74121

14

7

IC3

7486

14

7

IC4

7400

14

7

IC5

7400

14

7

IC6

7404

14

7

IC7

7493

5

10

ice

7493

5

10

IC9

7495

14

7

IC10

7495

14

7

IC11

7493

5

10

IC12

7493

5

10

IC13

7495

14

7

IC14

7495

14

7

IC15

NE555

8

1

5V

A

y FREQUENCY

*? ADJUSTMENT

IOK

ICI5NE555

RESET VCCDISCHARGE

OUTPUTTHRESHOLDTRIGGERGROUND BYPASS

iO.ljiF

rh

O.OI/iF

9h-

J

Figure 2: High-resolution, static interface.Each potentiometer in the joystick con-trols the pulse width of a one-shot. Thepulse width can vary from 35 ms at full-scale to 100 /as at 0. If a joystick with 4potentiometers is used, a duplicate circuitmay be constructed for the 3rd and 4thpotentiometers.

function which has a pulse width pro-portional to joystick position. Figure2 illustrates an interface design whichuses this technique.

The 2 joystick potentiometers Rland R2 control the pulse width of aone-shot (monostable multivi-brator). The one-shot has a pulsewidth of 35 ms when the poten-tiometer is at 50 k ohm full scale andsomething less than 100 lis at 0% offull scale. A 7.5 kHz clock signalasynchronously triggers the one-shots.When the one-shot fires, its durationis proportional to the joystick posi-tion and will vary from approxi-mately 0 to 35 ms. Using midscalepulse width of 17 ms as an example,the circuit timing is as in figure 3.

On the leading edge of the one-shotsignal, a clear pulse is generatedthrough an edge detector configured7486 device. The clear pulse resets the2 7493s which form an 8-bit counter.Once cleared, the counters startcounting clock pulses for the durationof the one-shot's period. On its trail-ing edge, a load pulse is generatedwhich loads this 8-bit count into an8-bit storage register. The computer isconnected to read this 8-bit valuethrough a parallel input port. Suc-cessive clearing and counting opera-tions update the register every 35 msor so (worst case). The clock rate is7.5 kHz which has a period of 133 /xs.If the one-she has a pulse width of 17ms, then 127 clock pulses would be

CLOCK

ONE SHOT Q

jil.

gated to the counter. Of a total possi-ble 255 counts, 127 would represent50% of full scale.

Software-Driven Interfaces

So far I have discussed only staticinterfaces. If the computer used withthe joystick has sufficient speed andexcess computing time available, thenit is reasonable to use the computer todirectly determine the one-shotperiod.

Figure 4 shows a circuit whichdirectly connects to the computer busand demonstrates this technique. Thecircuit as shown is wired for I/O (in-put/output) port decimal 255 orhexadecimal FF. The 4 joystick poten-tiometers are used as the timingresistors on 4 NE555-type one-shots.When an OUT 0, FF is executed inassembly language, it triggers all 4one-shots. To keep track of the pulsewidths, a 74125 3-state driver gatesthe one-shot outputs onto the databus during an IN FF instruction. Bylooping through this program anumber of times and keeping track ofthe logic levels of the 4 one-shots, thecomputer can accurately determinejoystick position in terms of loopcounts of instruction times. Listing 1is a program which does this for 1potentiometer.

High-Resolution Analog-to-Digital

While all methods are in some wayanalog-to-digital converters, the last

7.5 KHz

CLEAR

LOAD

COUNT

0 TO 35 mSEC

20/iSEC

20MSEC

0 TO 255 PULSES

Figure 3: Timing diagram for interface of figure 2. The driving clock signal is 7.5 kHz.The one-shot can be triggered for periods of 0 to 35 ms, depending upon the position ofthe joystick. When a reading is to be taken, the counters are cleared. Counts are madeuntil the one-shot signal drops, and then a load signal is sent to the interface. At thispoint the counter is read to determine the position of the joystick.

September 1979 © BYTE Publications Inc 15

MVI

B

clear B

OUT

FF,0

trigger one-shots

AGAIN

INR

B

increment B register

IN

FF

read potentiometers

ANA

01

isolate bit 0

JNZ

AGAIN

continue as long as one-shot is high

HLT

value is in B register

Listing 1: A typical assembly language program for using the joystick interface of figure4. After the one-shots are triggered, the program loops and checks the status of bit 0.When this bit is set, the conversion value is in register B. This program assumes thatthere is only 1 value being checked, and it is being input through bit 0.

method is in fact an 8-bit absolute-analog-to-digital converter, typical ofthe type used in computerized meas-urement applications. ICl is an 8-bit

Number

Type

+ 5 V

GND

IC1

NE556

14

7

IC2

NE556

14

7

IC3

7430

14

7

IC4

7400

14

7

IC5

74125

14

7

digital-to-analog converter that pro-duces an output voltage proportionalto a digital input applied to pins 5thru 12. For a complete explanationof this device, I refer you to a pre-vious " Ciarcia's Circuit Cellar" arti-cle, "Control the World" (September1977 BYTE, page 30). This article alsooutlines calibration and test pro-cedures.

The 3 basic sections are acomputer-controlled voltage source(ICs 1 and 2), an analog-inputmultiplexer (IC3) which selects an in-dividual joystick potentiometer by a2-bit address code, and a comparator(IC4) which compares these voltages.In operation, the digital-to-analogconverter is first set to 0 V out (hexa-decimal 00 digital input to it) and 1potentiometer is selected through themultiplexer. If V0 from the digital-to-analog converter is less than Vin fromthe potentiometer, the output will belogic 0. Next, the digital-to-analogconverter input setting is incre-mented, and the comparator output ischecked again.

Eventually an input count will bereached which will exceed V,„. Thecomparator output will then be alogic 1. The digital-to-analog con-verter input count is now the value ofthe voltage V,„. The worst case re-quires 256 iterations using this

R| THRU R4ARE JOYSTICKPOTENTIOMETERS

+ 5V

ao rz>

TO

COMPUTER jCONTROLBUS

I/O r^.WRITE I

'^E>

READ I—>^

IC47400

I

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2

Ida

OUTPUTTHRESHOLD

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5

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2

3

1

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7

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n

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OUTPUTTHRESHOLD

DISCHARGE

CONTROLTRIGGER

"1

0.01/tF

FR3SOK

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OUTPUTTHRESHOLD

DISCHARGE

CONTROLTRIGGER

ICENE556

^-pO.OI^F

kR4/S 50K

OUTPUTTHRESHOLD

DISCHARGE

CONTROLTRIGGER

~zy*

O.OI/iF

HZ>°I

TO

COMPUTER

DATA

BUS

■£>»!

-O D3

Figure 4: Software-driven interface. If the computer can directly read the input from the joystick interface, the hardware required canbe greatly simplified. When hexadecimal FF is output to port 0, all 4 one-shots are triggered. The pulse width is then determined by aprogram running through a short loop looking at the logic levels of the 4 one-shots. Listing 1 shows a typical program for thisapplication.

16 September 1979 ft) BYTE Publications Inc

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BYTE September 1979 17

Number

Type

+5VGND

+ 15 V

+ 15 V

IC1

MC1408-L8

13

2

3

IC2

LM301A

4

7

IC3

CD4051

4

8

IC4

LM301A

4

7

DIGITAL-TO-ANALOG CONVERTER

+ I5V

FROM COMPUTEROUTPUT PORT I

B7 OB6 O-B5 O"

b4 o-

B3 O"

B2 O-

B| O-

B0 O

MSB 5

10

LSB 12

ICIMCI408LS

lo

-Vref

RANGECONTROL

COMPEN

i 33pF

-I5V

FROM COMPUTEROUTPUT PORT 2

B| O"B0 O-

10

IC3CD405I

OUTINI

IN2

IN3

IN4INH C

W*

I.8K

FULLSCALEADJUST2K

—y&—

?

?IN823A6"

OFFSETADJUST5K

—y&—

2.2K-WA<-

I^F

/77

2.7K_VW—

lMF

rn

47pF

4.7K—W\/-

:i50pF

LM30IA

; 3.3K

DIGITAL TO ANALOG CONVERTERSET FOR 0 TO 2.56V

JOYSTICK MULTIPLEX

VREF = 2.56V

FIRST PAIR OFPOTENTIOMETERS !

SECOND PAIR OFPOTENTIOMETERS

R4IOOK

Figure 5: High-resolution analog-to-digital conversion. This hardware-oriented devicemultiplexes 4 voltage inputs (from the joystick potentiometers) and has the capability ofhandling 4 more voltages.

method. A better technique is suc-cessive approximation where thecomputer progresses through abinary search to "zero in" on the finalvalue. A full explanation of suc-cessive approximation is delineated inmy article entitled "Talk to Me: Adda Voice to Your Computer for $35"(June 1978 BYTE, page 142).

With the digital-to-analog con-verter set for a full-scale value of 2.56V, each count is equivalent to 10 mV.Only 4 channels of the CD4051 areused for the joysticks, leavinganother 4 channels as auxiliary inputsfrom external sources. Thus it ispossible for this interface to serve adual role because of its high accuracy

COMPARATOR

-O VqUT

. 33pF

TO COMPUTERINPUT PORT 1

C>Bo

LM30IA

and resolution relative to the othermethods.

You should now realize that boththe design and construction of ajoystick interface are influenced bymany factors. It is not unusual to findone manufacturer charging $50 for ajoystick, while another charges $200.Resolution, accuracy, and softwareinteraction are the prime considera-tions. Where static inputs are re-quired, the hardware will necessarilybe more complicated. Resolution andaccuracy ultimately determine thecomplexity of the interface.

For simple spacewar-type games,the circuit of figure 1 should suffice.For more demanding applicationssuch as cursor control in a high-resolution graphics system, figure 5may be the optimum choice. Becareful when buying joystick inter-faces. Make sure that they mate withyour program requirements and yoursystem's abilities.

Next month's "Circuit Cellar"feature will discuss a stand-alone,light-emitting diode display board. ■

18 September 1979 © BYTE Publications Inc

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BYTE September 1979 19

Introduction toMultiprogramming

Mark Dahmke

8312 Selleck

600 N 15th St

Lincoln NE 68508

Multiprogramming has usuallybeen considered out of reach of theaverage personal computer experi-menter using a small or medium scalecomputer. Actually, anyone with aprocessor above the level of an 8008can operate a multiprogram ormultiuser system. The original pur-pose of multiprogramming was toallow more than 1 user to take advan-tage of a computer simultaneously.This increased the productivity of themachine by allowing programs to runwhile other programs were awaitinguser input, access to a disk, etc.

This may seem to conflict with theadvantages inherent in micro-processor based systems (single usersystems and low cost). However,there are many instances where theability to run more than 1 program ata time may be advantageous. Notethat the statement "more than 1 pro-gram may run at a time" does notmean simultaneous execution. That isthe definition of multiprocessing(more than 1 processor on the bus),not multiprogramming.

To describe multiprogrammingmore effectively, I shall refer to amore well-known function in com-puters: real-time interrupts. Supposewe are using a microcomputer tomanage the environment in a smalloffice building. Normally we want tocontinually poll (scan) the sensorsthat are distributed throughout thebuilding and adjust heating, coolingand lights on the basis of temperatureand time of day. Let us say that

during normal operation, someone inthe building wants to change thetemperature of an office.

One way to do this is to have avideo terminal and keyboard attach-ed to the system that generates an in-terrupt when a keyboard request ismade. Upon receiving the interrupt,the computer saves the status of thecurrent program and enters or trans-fers control to the keyboard readroutine. As soon as the user has madethe desired change, the system loadsthe old status information and returnsto the original program. This same in-terrupt technique could be used todesign a time shared system thatwould allow several terminals to behooked up to a processor. Each ter-minal would generate an interrupt,and whichever program was activewould be put in a wait state. Thisarrangement only works well for afew terminals, though. You can ima-gine what would happen if everyonehappened to press a key at the sametime.

Figure 1 shows timing comparisonsof several modes of operation alreadydiscussed. In figure la 2 independentprocessors are shown, each doingsomething different and neither in-terfering with the other. This isknown as multiprocessing. The pro-cessors may or may not be sharingI/0(input/output) terminals ormemory.

In figure lb 2 processors are shownin a master-slave arrangement.Perhaps the slave processor performs

floating point arithmetic or somecomplex I/O function. The masterprocessor can give the slave processorcommands via an interrupt and con-tinue other processing until the slaveinforms it that it has finished thedesired operation.

Figure lc shows a single processorwith an interrupt being applied. Theprocessor temporarily gives controlto the routine specified by the inter-rupt hardware and begins executingit. When complete, it returns controlto the main program. Figure Id showsthe multiterminal timeshare system.Usually the interrupt hardware con-tains provisions for daisy chaining orprioritizing the interrupts as theycome in. Thus, if terminal 6 appliesan interrupt and the processor is busywith terminal 7, terminal 6 is notallowed to interrupt the processoruntil terminal 7 is finished.

Using multiprogramming is likeusing real-time interrupts. A multi-programmed system uses interrupts,but in a more efficient way. Imagine asimple 2 program situation. Supposeprogram A is running and no other

About the Author

Mark Dahmke is currently employed by theUniversity of Nebraska Computer Network asa programmer/analyst in the Academic Com-puting Services section. He is also a seniorcomputer science major. At home, Morlc ownsan 8080 based system with 32 K bytes ofmemory and dual iCOM floppy disk drives.His work involves graphics, electronics,writing, systems programming and speech syn-thesis.

20 September 1979 © BYTE Publications Inc

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programs have been started. Then auser initiates (loads) another programcalled B. How will program B gaincontrol of the system so that it mightstart to execute?

The process of passing controlfrom one program to the next isusually handled by an operatingsystem module referred to as an inter-rupt call routine. Normally, to savethe programmer the trouble ofmaking sure that this routine getscalled at regular intervals, the routineis usually imbedded in many of theI/O driver routines or other standardutility subroutines on a system. Notethat this technique will in no wayupset any of the flags or registers ofthe routine it is called from.

This interrupt call program will:

1. Determine if any other programsare waiting to execute.

2. If so, save all registers and flags onthe stack and save the address ofthe current program's stackpointer in a special table inmemory.

3. Load the new program's stackpointer from the table, pop allregisters and flags off the stack.

4. Return to the new program.

Loading the new stack pointerraises some interesting questions. Ifprogram B has not yet begun, howcould its registers have been pushedonto its stack? Figure 2 shows thestacks of both programs as theywould be at each step in the previous-ly described interrupt call routine.Part of the job of the routine that in-itialized program B is to set up adummy stack and stack pointer suchthat the program counter address onthe top of the stack contains the entry

point of program B. Thus, when theinterrupt call routine reaches step 4, itwill execute a return instruction, thenpop the entry point address off thestack and begin executing program B.When the interrupt routine is calledagain, it will see that program A iswaiting and will save all of programB's registers and flags, swap stackpointers and return to program A atthe point where it was first inter-rupted.

All this activity will take placeevery time the interrupt routine iscalled, but if one of the programs getscaught in an infinite loop, the inter-rupt call routine may not get called.The simplest way to avoid this kindof problem is to add some hardwareto provide external timed interrupts.As shown in figure 3, the interrupttimer is set to provide an interruptevery 10 ms. A reset line is provided

PROCESSOR

PROGRAM A

PROGRAM A

PROGRAM A

PROGRAM A

PROGRAM A

(a)

PROCESSOR 2

PROGRAM B 10

PROGRAM B

PROGRAM B

10 PROGRAM B

PROGRAM B

PROGRAM 8

(b)

(c)

(d)

PROGRAM A

PROGRAM ACONTINUESOTHER WORK

PROGRAM A /

SLAVE PROGRAM INITIATEDSLAVE 1

SLAVE SENDS READY SIGNAL

INACTIVE ORDOING OTHER WORK

PROGRAM ASLAVE PROGRAM

INACTIVE OR DOING OTHER WORK /

/ EXTERNAL INTERRUPT

/ OCCURS

PROGRAM A

INTERRUPT ROUTINE

PROGRAM A RESUMED /

OPERATING TERMINAL 0SYSTEM SERVICED

OPERATINGSYSTEM

TERMINAL 7SERVICED

TERMINAL 6SERVICED

TERMINAL 7COMPLETED

TERMINAL 6COMPLETED

OPERATING/SYSTEM /

TIME

Figure 1; Timing diagrams for 4 different system organizations. Figure la is a multiprocessing example using 2 independent pro-cessors. Figure lb is a multiprocessing example using 2 processors connected in a master-slave configuration. Figure lc is a single pro-cessor with 1 level of interrupt. Figure Id is a single processor with 8 levels of interrupts. Each of the 8 levels is activated by 1 of 8 ter-minals.

22 September 1979 © BYTE Publications In

STACK A

STACK POINTER A

'

11)

PROGRAM COUNTER(HIGH)

—

PROGRAM COUNTER(LOW)

AFTER INTERRUPT CALLSTACK B

(3)

PROGRAM COUNTER

(HIGH)

PROGRAM COUNTER(LOW)

ALL REGISTERS

FLAGS

STACK POINTER B

(STACK POINTERSAVE AREA)

(2)

PROGRAM COUNTER(HIGH)

PROGRAM COUNTER(LOW)

ALL REGISTERS

FLAGS

STACK POINTER A

(STACK POINTERSAVE LOCATION)

STACK B

(4)

STACK POINTER B-

PROGRAM COUNTER(HIGH)

PROGRAM COUNTER(LOW)

Figure 2: Arrangement of all stacks and stack pointers at each interval of an interrupt call routine.

in the event that the interrupt routineis manually called (through the soft-ware method). The timer may bereset to give the program its full 10ms. A disable line is provided toallow the user to turn off the timer forspecial applications (software timing)in which the processor must not be in-terrupted.

Figure 4 shows our previous exam-ple of figure 1, but with the extrahardware generated interrupts added.In figure 4a some software interruptsare mixed in with the hardware inter-rupts. The timer is reset after each callto the interrupt routine. Figure 4b isthe same except that the timer is notreset after each call.

A Complete System

There are limitless ways to goabout developing a computer systemthat will be easy to use. A look at thecurrent market shows this to be true,perhaps even to a greater extent onthe small systems level. I will not at-tempt to describe all possible varia-tions available on a multiprogram-

ming system, but I will try to give as The following are essential:generalized a view as possible.

First, we must consider what is 1. Some form of operating systemnecessary to make a useful system. that allows simplified user com-

4>

£~

470ft

4—va—

0s

(THREE STATE)

>

C^

-[ ~> TO INTERRUPTLINE OFPROCESSOR

D FLIP-FLOP

o

Figure 3: Simple hardware interrupt timer set for 10 ms intervals.

September 1979 © BYTE Publications Inc 23

TIMER RESETBY SOFTWARE

TIMER RESETBY SOFTWARE

TIMER RESETBY SOFTWARE

(a)

PROGRAM A

PROGRAM B

PROGRAM A

PROGRAM B

PROGRAM A

PROGRAM B

PROGRAM A

PROGRAM B

TIMERINTERRUPT

TIMERINTERRUPT

10

INTERRUPT

CALL

TIMERNOT RESET

TIMERINTERRUPT

TIMERINTERRUPT

10

INTERRUPT

CALL

10

INTERRUPT

CALL

TIMER

NOT RESET

(b)

PROGRAM A

PROGRAM B

PROGRAM A

PROGRAM A

PROGRAM B

PROGRAM B

PROGRAM A

TIMERINTERRUPT

TIMERINTERRUPT

10

INTERRUPT

CALL

TIMER

INTERRUPT

TIMERINTERRUPT

10

INTERRUPT

CALL

TIMERINTERRUPT

TIMERINTERRUPT

10

INTERRUPT

CALL

Figure 4: Interrupt timing example of figure 1 reviewed with the addition of a hardware timer. The timer may be used in 2 ways: Theexample in figure 4a resets the timer on each interrupt call. This allows each program to receive its full 10 ms time slot. The example infigure 4b does not reset the timer. Therefore, a hardware interrupt occurs every 10 ms.

munications (ie: BASIC, DOS,CPM).

2. Convenient mass storage I/O(cassette or disk).

3. Sufficient memory to handle allprograms.

Another consideration might be theinternal architecture of the processor,but that is another level of problem.

Figure 5 shows the memory layoutof a typical multiprogrammingsystem. To maintain a simple system,I have combined the operating system

with the timesharing routines thatsupport all terminals (video displays,keyboards and teletypewriters). Thismeans that each time the operatingsystem gains control (through aninterrupt call or timer interrupt), itwill complete its own activity andthen transfer control to the time-sharing program for the remainder ofthe time slot. If the operating systemis given highest priority, the responsetimes of the terminals should not suf-fer. The operation of the timeshareprogram can be treated as a multi-

BOOTSTRAPLOADER

INTERRUPTROUTINE

TIME-SHARINGSUPPORTPROGRAM

ALL I/OROUTINES

OPERATINGSYSTEM (0)

STACK 0

USER PROGRAM 1

STACK 1

USER PROGRAM 2

STACK 2

~~ —^

Figure 5: System geography of a typical multiprogramming system with space for theoperating system and 2 other programs.

program system in miniature, whereeach terminal is given a time slot, or itmay be designed to simply scan theterminals, choosing a new terminaleach time it is given control.

Controlling I/O

Many programmers have dis-covered the convenience of vectoringall I/O through 1 subroutine; thissimplifies programming greatly andmakes system changes much easier.Typically, 1 subroutine will accept anoperand (if necessary) and anoperator function code passed fromthe main program and will decidewhich I/O function to perform. Inmy hypothetical computer, this ap-proach will be used. Note that insome large computer systems, theI/O driver programs can only be ac-cessed by executing a special kind ofinterrupt call that informs theoperating system that the user's pro-gram desires to perform some kind ofinput or output operation. The oper-ating system then takes charge, per-forms the I/O for the program inquestion, and returns pointers tellingwhere the input data was stored inmemory or that the requested outputfunction has been completed.

This type of I/O handling is neces-sary because the I/O controllers areextremely complex and are capable ofperforming an entire I/O operation

24

September 1979 © BYTE Publications Inc

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without processor intervention. Infact, it would be very inefficient tomake the processor of a large systemperform these menial tasks when itcould be working on more importantprograms. In microcomputer systemswe are not normally concerned withthe optimization of I/O functions andit does not really hurt performance tohave the processor perform most ofthe I/O. Consequently, the I/Odriver routines in the system I amdescribing will not be considered aspart of the operating system. Theyare just utility subroutines that maybe called by the user's program.

Defining the Necessary Tables

With only 2 programs very few, ifany tables are needed to tell the inter-rupt routine which program was ac-tive at the instant the system was in-terrupted and which program is nextin line. But imagine a system capableof supporting 10 or more programs:some form of priority scheduling willbe needed, as well as a table to holdall of the stack pointers of the inactiveprograms.

To handle the list of programs(herein referred to as tasks), we mustdefine a task control table that keepstrack of a number of pointers anddescriptors. First, each entry willbegin with the task number that uni-quely defines each task. Next, we willinclude the priority of the task on anarbitrary scale of 0 to 10. It will thenget the processor before a task oflower priority (10 is highest). If 2tasks have the same priority, the firstone in line in the task control tablewill get control. The task controltable must also keep track of the lastvalue of the stack of each task andwhether or not the task may be inter-rupted (in the case of critical timingloops).

Another important status byte thatmust be kept is the current activityindicator. This byte contains the tasknumber of the currently active task.Now let us assume that we have 3 dif-ferent tasks running and all have beeninitialized (stored in the task controltable). The first task has a tasknumber of 0 and a priority of 10.Generally the operating system is

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given the task number 0 designation.Since the operating system andtimeshare program (user terminals)are considered one big program inthis example, task 0 is also thedesignation of the timeshare system.Task 1 is a program that one of theusers submitted (initiated) from a ter-minal; it has a priority of 10. Task 2was also loaded and initiated by auser through the timeshare terminals,and it has a priority of 10.

Imagine that the timeshare pro-gram calls the I/O driver program towrite a character out to a terminal.Since there could be many terminalsconnected to the system, how doesthe program know which one to writeto? It would be very inefficient tohave different routines for eachdevice, but the only way that a pro-gram could tell the I/O driver whichspecific display to write to is for thecalling program to know the physicaladdress of that terminal. Passing theactual address of the device ruins theneatness of the I/O routine, though.It is more convenient to specify thefunction to be performed (1 = writeto video display; 2 = read keyboard;3 = write to cassette; 4 = readcassette).

The solution is to have another en-try in the task control table called acommunications control blockpointer that points to the location ofthe communications control block forthe particular task. Since each task isgiven its own block, the user maydefine his or her own functions andaddresses. Thus each program mayhave its own video display, key-board, cassette interface and disk.The communications control blockcontains a list of function numbers,the address of the I/O port ormemory mapped port, and the ad-dress of the I/O subroutine that willperform the operation. Figure 6shows the arrangement of all tables.

Starting and Stopping

To initialize a new task, the useradds entries to the appropriate tablesthrough a console command andcauses a dummy stack and stackpointer to be created. To stop a task,the last thing done in the task is to calla subroutine that would remove itstask control table entry. This isequivalent to a CALL EXIT in FOR-TRAN found on many largersystems.

26 September 1979 © BYTE Publications Inc

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BYTE SeptemoeP

CURRENTACTIVITYINDICATOR

COMMUNICATIONS

CONTROL

BLOCK

(ONE FOR EACH TASKCONTROL TABLE ENTRY)

I/O

FUNCTION

CODE

I/O ROUTINEADDRESS TOHANDLE THISFUNCTION

I/O PORT ORMEMORY MAPPEDADDRESSASSIGNED TOTASK # n

END OF TABLE MARKER(HEXADECIMAL FF)

COMMUNICATIONS

CONTROL

BLOCK

L—

COMMUNICATIONS

CONTROL

BLOCK

L-

Figure 6: Control table organization. The current activity indicator contains the task number of the active task. The task control tablecontains the task number, task priority, last value of stack pointer, interrupt status flag (1 for yes, 0 for no interrupts), and thepointer to the task's communications control block. The communications control block contains the I/O (input/output) functioncode, address of I/O driver routine associated with the function code, and the I/O port or memory mapped address assigned to thetask for the particular function. One entry is provided for each function code used in the task. The owner of the task may add entriesto the communications control block for specialized I/O driver requirements.

Example

The easiest way to show how alltables and pointers affect each otherand the system is to observe themduring a short period of machine ac-tivity. As we begin, task 0 (theoperating system and timeshareroutines) has control, and a timerinterrupt is occurring. There are 2other tasks in memory: task 1 haspriority 5 and task 2 has priority 4.

First, as the interrupt routine isentered it saves all registers and flagsof task 0 on stack 0 and saves the task0 stack pointer in the task 0 task con-trol table entry (see figure 7). Next, itscans the task control table for thetask of next highest priority, movesthe new task number (task 1) to the

current activity indicator, moves thetask 1 stack pointer from the taskcontrol table to the processor's stackpointer, pops all of task l's registersand flags off of stack 1, and executesa return, which has the effect of pop-ping the program counter and jump-ing to that address.

Task 1, while executing, en-counters a call to the I/O driverroutine with a request for a keyboardinput (see figure 8). When the I/Odriver routine is entered, it scans thetask control table to find the com-munication control block pointerentry for task 1 (the routine deter-mines which task called it by lookingat the current activity indicator), thenscans the communication control

block for the function number entrycorresponding to the one passed bythe main program. Even though thecomputer may have 5 or more key-boards attached to it, the port addressfound in the communication controlblock gives it the address of thekeyboard assigned to task 1.

Since the keyboard read routine isa common one, the address referredto in the communication controlblock points to a subroutine locatedwithin the operating system area.Note that if the user had need forsome special I/O subroutine, hecould locate it in his own memoryarea and put the address in his com-munication control block as anotherfunction code.

28 September 1979 © BYTE Publications Inc

Returning to the example, thekeyboard read subroutine is calledfrom the I/O driver, reads thekeyboard port assigned to task 1, andreturns to the I/O driver with theASCII code. The I/O driver returnsto the main program with the ASCIIcode in a register or memory loca-tion. In figure 9 the next timer inter-rupt has occurred, so control returnsto the interrupt handler routine.Again, the interrupt routine saves allregisters and flags of task 1 on stack1, looks at the current activity in-dicator to see which program was lastactive, saves the stack pointer in thetask 1 task control table entry, scansthe task control table for the nexthighest priority task, and finds thattask 2 should get control. The stackpointer for task 2 is loaded from thetask control table, all registers andflags are popped off of stack 2 andagain a return is executed that causestask 2 to take control.

In the next step (shown in figure10), task 2 has encountered theequivalent of a CALL EXIT or STOPcommand and has finished process-ing. This CALL EXIT calls a ter-minator routine which again finds outwho called it (via the current activityindicator) and simply eradicates thetask control table entry for that task.To keep things neat, all succeedingtable entries are moved up 1 notch.Then, control is returned to the inter-rupt handler, which will find the nexttask in line. In this case, since noother tasks of lower priority arewaiting, control is returned to thehighest priority task 0.

Error Handling

On a single program system, errorhandling is something that the usercan watch for manually. Whenseveral programs are running, thesystem must have routines to handleerrors rapidly so that other programswill not be slowed down ordestroyed. There are many commonerrors that are relatively easy to dealwith. Executing an invalid op code orforgetting to put in the 2nd or 3rdbyte of a multibyte op code can behandled through a simple systemrestart (through the interrupt handlerroutine) without losing continuity.But what about a program loop thataccidentally destroys part or all ofanother user's program? On an IBM360, all memory blocks assigned to a

TRANSFER OF CONTROLDATA OR POINTERS

Figure 7: Task 0 has control of the processor and has just been interrupted. The inter-rupt routine looks at all pointers, saves the status, and then transfers control to task 1.

task are given a unique 4-bit protectkey (which is the same as the tasknumber) that is stored in externalhardware.

One approach might involvehaving 2 external 16-bit registers thatcould be loaded by the interruptroutine with the high and lowmemory addresses of the active task.

Then, every time the address bus hasa valid address on it, it is testedagainst these registers. However,special precautions would have to betaken in those cases in which a utilityin low memory (I/O driver routineetc) is called, or when memory map-ped I/O ports outside these addresslimits are used.

■ TRANSFER OF CONTROL: DATA OR POINTERS

BOOTSTRAP

LOADER

„---

INTERRUPTROUTINE

1 I/O DRIVER

/ ! * i

— "■"

'/ 1/ 1 / |

/KBD/IN Jf' ) \

\0 1 \

^ -*

/

CURRENTACTIVITYINDICATOR

s /

/ /

S S .

/ / *

TASKCONTROL

TABLE

COMMUNICATIONSCONTROL BLOCK 0.

STACK 0 1

TASK 1

COMMUNICATIONSCONTROL BLOCK 1

STACK 1

__ ^^

Figure 8: Task 1 has requested keyboard input from its assigned keyboard. When theinput is completed, the I/O (input/output) driver returns control to task 1.

September 1979 © BYTE Publications Inc 29

= TRANSFER OF CONTROL■ DATA OR POINTERS

Figure 9: Task 1 has been interrupted and turns control over to the interrupt routine.Control is then passed to task 2.

■■ TRANSFER OF CONTROL

.— = DATA OR POINTERS

BOOTSTRAPLOADER

INTERRUPTROUTINE

1

CURRENTACTIVITYINDICATOR

N /

TASKCONTROL

TABLE

^

COMMUNICATIONSCONTROL BLOCK

TERMINATOR

STACK 0

/ *

TASK 1

COMMUNICATIONSCONTROL BLOCKONE

STACK 1

TASK 2

COMMUNICATIONSCONTROL BLOCK 2

STACK 2

Resolving Allocation Conflicts

Allocating I/O devices has been aproblem since the early days of com-puters. Devices like tape drives andcard readers (sequential devices) arenonshareable: only 1 program mayuse them at a time. However, diskdrives are considered shareable, sincethe head may be positioned at ran-dom to gather data. The simplestmethod that can be applied to thesystem described in this article wouldbe to have the initiator programcheck all communication controlblocks to make sure that certaindevices are not assigned more thanonce.

I/O Software Considerations

As mentioned earlier, I/O techni-ques in use on small systems leave allcontrol up to the processor. If specialtiming is needed or if strobes or readyflags have to be checked, software isused instead of extra hardware, as inthe case of larger systems. This initself is good from the standpoint ofeconomy, but requires that specialcare be taken when writing the driverand controller software.

For example, suppose a cassetteread routine uses a universal asyn-chronous receiver transmitter(UART) implemented in software asan algorithm instead of hardware. Ina nonmultitasking system, the pro-gram may simply loop and timedown between bits, but in a multitasksystem the timer interrupt wouldsurely halt the activity and executeother programs. It may be well over30 ms before it can return to thecassette read routine. It is easy to seewhat can happen to critical timingloops on a system that uses any kindof interrupts.

The solution? If you must do thecritical timing in software, it isnecessary to turn off the interrupttimer while in the critical loop andreactivate it when in noncritical partsof the routine. If external hardware isused, and internal timing is reduced

Figure 10. Task 2 has completed its execu-tion and encounters a CALL EXIT. Con-trol is given to the terminator routinewhich performs some cleanup operationsand removes the task 2 entry from thetask control table, effectively destroyingthe task. Control is then given to the inter-rupt routine which again scans the taskcontrol table to find the next task awaitingexecution.

30 September 1979 © BYTE Publications Inc

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to noncritica] loops, the interventionof the multitask interrupt timer willnot normally affect the system. If theinterrupt timer causes an interruptjust before a byte is received by theUART but returns in time for thenext byte to be received, the easiestway to assure that the cassette readroutine does not drop a byte is to setthe timing of the interrupt oscillatorto at least twice as fast as thetransmission rate of the UART. Thisgreatly reduces chances of losing abyte.

An alternate approach is to haveeven more hardware that forces theinterrupt timer to timeout and returncontrol to the program awaiting thedata transfer operation when the in-coming data is present. A third wayinvolves the use of direct memory ac-cess (DMA) capability, in which theexternal controller reads the UARTand deposits the data directly intomemory. With this approach, thecalling program need only initializethe external registers and go into await state until the transfer is com-plete, allowing the rest of the tasks to

execute normally. This last approachis used on many large systems andconstitutes what is called a channel.

Managing the System

As you can see, many levels of ac-tivity are required to control amultiprogramming system properly.It is also apparent that some minimalhardware is required to prevent oneuser from obtaining exclusive controlof the processor or writing oversomeone else's program or data. Theuse of control tables and a standardinterrupt routine are also importantas a way of letting the interruptroutines and I/O drivers know whichtask had control of the processor last.

If the user plans to run BASIC soft-ware or some other kind of languageinterpreter, the safety featuresdiscussed earlier may be implementedas part of the interpreter. To run alower-level operating system thatallows the user to generate assemblerlevel code will generally require thehardware described in this article,thus safeguarding the system and itsusers from accidental loss of pro-

grams or data. In general, the use oftimed interrupts allows for a fairlyeven distribution of processoractivity, and depending on the cycletime of the host system, between 4and 12 tasks may be handled withouttoo noticeable a delay in responsetime.H

REFERENCES

Abrams, Marshall D, and Stein, Philip G,Computer Hardware and Software, Addison-Wesley, Reading MA, 1973.

• Davis, William S, Operating Systems,Addison-Wesley, Reading, MA, 1977.

Martin, Donald P, Microcomputer Design,Martin Research Ltd, Northbrook IL, 1976.

Signetics Data Manual, Signetics Corpora-tion, Sunnyvale CA, 1976.

Struble, George W. Assembler LanguageProgramming: The IBM System 360 370, se-cond edition, Addison-Wesley, Reading MA,1975.

Tanenbaum, Andrew S, Structured Com-puter Organization, Prentice-Hall, EnglewoodCliffs NJ, 1976.

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Interface a Chessboardto Your KIM-1

Jeff Teeters

1720 Coolidge Ct

Eau Claire WI 54701

Chess is a fascinating game. Com-puter chess is especially fascinatingbecause the complex analysis whichdetermines each move is performedby a machine instead of a human.Computer chess offers an excellentway to demonstrate the power andversatility of personal computers.

Most computer chess systems areunable to "see" a chessboard. A

human playing against a computerwill usually set up a chessboardbeside the computer, and the moveswill be communicated to and fromthe machine through the use of akeyboard and a display in some typeof abstract notation.

Keyboard entry of moves is unde-sirable. It is inconvenient, errorprone, and inelegant. The abstract

Photo 1: Two pawns, a White Knight, and a loose rivet are shown on top of the elec-tronic chessboard. One row of 8 light emitting diodes (LEDs) is placed along the left sideof the board, and another row is placed along the bottom of the board as seen by thehuman player. Two LEDs are lit to indicate a single square, using an X, Y axis system. Asingle large hole is drilled in the center of each square to accept entrance of the rivetwhich is glued to the bottom of each chessman. The rivet completes an electrical circuitbetween 2 pieces of wire that run from smaller holes through the large central hole. Thisswitching arrangement allows the computer to detect the presence or absence of a pieceat each square of the board. In this prototype, an additional set of 3 wires is seen in eachsquare; these wires remain from an earlier, unsuccessful switching attempt.

notation promotes errors and makesplay difficult for people who do notknow the notation system. Further-more, errors may not be detected un-til many intervening moves haveoccurred.

An ideal chess-playing systemwould contain a digital televisioncamera to observe the board and amechanical arm to move the pieces.[A mechanical arm designed forexactly this application was describedin the article "A Hobbyist RobotArm," by Keith Baxter and TimothyDaly in the February 1979 BYTE,page 84...RSSj A less costly alter-native is to construct a chessboardwhich can electronically com-municate with the computer. Thecomputer may then "look" at theboard position through its l/0(in-put/output) ports. A means of in-dicating the computer's moves on thechessboard itself may also be pro-vided.

In the system that I have con-structed, the user makes his move onthe electronic chessboard, instead oftyping each move on a keyboard. Thecomputer's moves are displayed onthe chessboard through the use ofdiscrete light emitting diodes (LEDs),arranged in an X,Y coordinate sys-tem. The LEDs show the user exactlywhich chessman the computer wantsto move, and to which square.In addition to being aestheticallypleasing, this system makes it im-possible to enter your move in-

About the Author

Jeff Teeters is an undergraduate student atthe University of Wisconsin at River Fallswhere he majors in mathematics.

34 September 1979 © BYTE Publications Inc

correctly, and easy to interpret thecomputer's move. The board iscontinuously scanned so that even ifthe user moves the computer's pieceincorrectly, the mistake is detectedimmediately. A speaker is connectedto the computer to let unwary usersknow (by a buzz) when they misinter-pret a computer move. This speakeralso emits a brief sound when thechess program has decided on a moveand when it has been recorded intothe computer's internal boardrepresentation.

This project is designed for specificuse with Peter Jenning's Microchess,running on a KIM-1 with about 0.5 Kbytes of extra memory. Imple-mentation on other 6502 based com-puter systems should be relativelyeasy since only a few minor softwaremodifications would be needed. Therequired hardware consists of a chessset, a package of cheap switchingdiodes, 2 integrated circuits, 16discrete LEDs and 32 copper rivets.

The chessboard should have a thin,nonconductive surface that is easy todrill holes through. This surface mustbe supported by side panels so there isa hollow space of about 2 cm underthe board for wiring. I used a cheapplywood chess set that is designed tofold into a storage box for thechessmen. The copper rivets shouldbe small in diameter, about 12 mmlong, and have a flat top. The onesthat I used were size 9 rivets manufac-tured by the Tower Corporation ofMadison IN.

System Concepts

KIM-1 Microchess uses an internalboard-status table to keep track of thewhereabouts of the chessmen. Thistable contains 32 square numberswhich indicate the position of the 32pieces. It is important to realize thatMicrochess generates moves solely onthe basis of what is in that table, andnot how it was placed there. My planof attack was simple. I had only towire a chessboard to the computerand write an interface program thatwould translate moves on the chess-board into changes in the table. Sincethis program will be needed onlywhen moves are physically beingmade, it can be called fromMicrochess and used in place of theMicrochess keyboard I/O (input/out-put) routines. After the user hasfinished moving, control can be

Photo 2: The bottom of the chessboard. The switching diodes and connecting wires aresoldered directly to the wire contacts in the central holes. The 2 integrated circuits aretype SN74154 decoder/demultiplexers. Note the tips of rivets protruding through someof the holes.

transferred back to Microchess tocompute the machine's next move.

The Microchess to chessboardinterface program is logicallystraightforward. If no move is beingmade, the table should be an accuraterepresentation of the board. A moveis detected when the table does notcorrectly represent the current boardposition. If an empty square appearson the board where the table indicatesthat a chessman resides, then the userhas just picked up that man. If thetable shows an unoccupied squarewhich the board indicates is occu-pied, a chessman has just been setdown in that square. A move is con-stituted by the user picking up a manand setting it down in some otherlocation. A capture is completed bypicking up 2 men and setting 1 downin the space formerly occupied by theother. Because the Microchess table isupdated each time a simple move orcapture is made, the table alwaysgives an accurate representation ofthe current board position.

Hardware Details

Note that the chessboard interfaceprogram can keep track of the movesthat are made simply by knowing ifindividual squares are occupied by apiece or are empty. The circuit which

Photo 3: The complete chessplaying sys-tem. The completed electronic chessboardstands in the foreground. The chessboardand the sound-effect speaker are con-nected to the KIM-J computer residing inthe suitcase in the background.

provides this information to the com-puter is illustrated in figure 1. Forpurposes of square identification, thechessboard is conceptually cut inhalf. The 2 pieces are placed logicallyend to end, forming an arrangement

September 1979 © BYTE Publications lnc 35

2.S0/

BREAKING THE SOUND BARRIER

THE TRAP DOOR

33s6BT

September 1977

March 1979

Byte Cover Prints -Limited Editions.

The September '77 and March '79 covers of BYTEare now each available as a limited edition art print,personally signed and numbered by the artist,Robert Tinney.

These prints are strictly limited to a quantity of 750for each cover, and no other editions, of any size,will ever be published. Each print is 18" x 22",printed on quality, coated stock, and signed andnumbered in pencil at bottom.

The price of each print is $25. This includes 1) asigned and numbered print; 2) a Certificate ofAuthenticity, also signed personally by the artistand witnessed, attesting to the number of the edi-tion (750), and the destruction of the printing plates;and 3) first class shipment in a heavy-duty mailingtube.

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36 BYTE September 1979

Circle 369 on inquiry card.

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Figure 1: Circuit which determines whether or not a given square is occupied. The chessboard is conceptually cut in half. It is placedso that the squares form a 4 by 16 matrix. For each square, a diode and a switch are wired in series between the appropriate row andcolumn lines. A closed switch indicates an occupied square; an open switch indicates an empty square.

of 4 rows and 16 columns. A diodematrix allows the hardware to iden-tify the individual squares.

The integrated circuit in figure 1 isa type SN74154 4 to 16 line decoder/demultiplexer. The 4 input lines to thedevice are connected to the KIM-1I/O port A. Each of the 16 outputlines is linked to a column in thematrix. This portion of the circuitallows the KIM-1 to select 4 squaresout of the total of 64. The 4 rows ofthe matrix are connected to the I/Oport B. Row and column addressingallows scanning of a single square.Each square of the chessboard has aswitch. A closed switch indicates thatthe square has a piece on it; an openswitch shows that the square isempty.

To determine whether or not apiece is on a particular square, theinterface program first selects thecolumn by sending the correct binary

code to the 4 input lines on theSN74154. This brings 1 of the 16 out-put lines low, while the diodes keepthe rest high. If the switch is closed(ie: a piece is on the square), then thecorresponding row-line will be pulledlow and the matching port-B dataregister bit will be a 0. Thus,by select-ing the column through port A andtesting the row bits in port B, it ispossible to determine the status ofevery square on the board.

Switch Experimentation

Now for the hard part: what can beused as a switch? The actual mechani-cal operation remains the only unre-solved detail. All that is needed issome means of closing the switchwhenever a piece is set down, andopening it when one is picked up.There are several ways to accomplishthis—some of which are better thanothers.

In my first attempt I put aluminumfoil on the bottom of the pieces andused simple wire contacts on top ofthe board. I punched 6 holes into eachsquare using a large needle to formthe corners of 2 concentric, equi-lateral triangles. Three strands ofwire were looped through the holesforming 3 symmetric contacts (seefigure 2a). The third contact was usedonly to balance the pieces.

The concept is simple. The piece isset on top of the wire contacts and thealuminum foil makes the necessaryconnection. Unfortunately it didn'twork. The contacts were not suffi-ciently stable, and the slightest vibra-tion rocked the pieces, leading theprogram to believe that the user wastrying to move 5 or 10 pieces at once.

That problem might have beensolved by mounting magnets on thepieces and using a chessboard with anonconductive magnetic surface.

38

September 1979 © BYTE Publications Inc

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BYTE September 1979 39

COLUMN

Figure 2a: The first attempt to form aswitch for the squares. Three symmetriccontacts on top of each square were madeby looping bare wire through holes in theboard. Two of the contacts were wired tothe row and column lines on the back sideof the board. (The third wire was simplyto balance the piece upright.) The pieceshad aluminum foil glued to their bottoms.When such a chessman was set down onthe contacts, electrical continuity wasachieved. Unfortunately, vibrationcaused intermittent contact and confusedthe computer.

COLUMN

Figure 2b: The second attempt to form asquare switch. This attempt wassuccessful. Copper rivets were glued tothe bottom of the chessmen. A large holewas drilled in the center of each square toreceive the rivet. Two wires were loopedthrough the large central hole from 2smaller holes (left over from the firstswitch attempt). The rivet closes the elec-trical circuit.

ROW

COLUMN

Figure 2c: Illustration of the appearance ofa square which uses rivet switches, andwhich previously did not have othermethods installed in it. The reader may doit correctly the first time.

Another possibility would be toeliminate wire contacts entirely anduse reed switches or some type ofphotocell. Unfortunately, one suchdevice must be mounted under eachsquare, necessitating a total of 64devices. Although they would haveundoubtedly worked, 64 photocellsor reed switches would have costmore than I was willing to spend onthe project.

Switch Success

I eventually figured out a contactmethod that was both cheap andreliable. I drilled a small hole in thecenter of each square, just largeenough to slide in a copper rivet. Twostrands of bare copper wire from 2 ofthe inner contact holes used in my firstattempt were looped through thelarger central hole forming 2 contactsinside of the hole (see figure 2b). Thefelt on the bottom of the pieces waspeeled off and the tapered copperrivets were glued onto the metalweight underneath the felt with an in-stant bonding adhesive.

I have found that these contactswork quite well. The tapered copperrivets slide easily in and out of thehole, while slight pressure from thesides of the hole forces the rivet tomake good contact with the copper

wire. The pieces remain intact and theelectrical contacts remain solid, evenwhen the chessboard is held upsidedown and shaken gently. Of coursewhen you wire your chessboard, youshould leave out the 3 symmetricwires that I tried on my first version.Only the 2 strands which were loopedthrough the rivet hole need to be in-stalled (see figure 2c).

Hardware for Computer Output

The LEDs are wired according tofigure 3. The integrated circuit isanother 4 to 16 line decoder whose 4inputs are connected to the I/O ports.Note that decoder outputs 0 thru 7are connected sequentially to therank— indicating (Y axis) LEDs withthe 0-bit output being connected tothe uppermost LED. Likewise, thefile—indicating (X axis) LEDs areconnected left to right with outputs 8thru 15. The chip-enable line is con-nected to I/O port pin PBO so that theLEDs can be turned off while Micro-chess is computing a move.

Mounting of the LEDs on the sidesof the chessboard is relativelystraightforward. I used a large needleto punch the holes for the leads priorto insertion. Glue can be used to holdthem in place. Be sure to orient thechessboard so that a white square is

in the lower right-hand corner of theside facing the human player. Thismeans that the 2 rows of LEDs install-ed on the left side and bottom of theboard will meet at a corner contain-ing a black square.

The speaker is connected to outputport pin PAO in the manner describedin the K1M-1 User's Manual on page57. See figure 4 for an illustration ofthe I/O port connections.

Software

The necessary modifications toMicrochess are shown in listing 1.The Microchess to chessboard inter-face program with source and objectlisting is given in listing 2. Although Iused a nonstandard meta-assembler,most of the mnemonics are similar to,if not the same as, the MOS Techno-logy standard mnemonics. Thelistings are fairly well documented.

There are, however, some generalconcepts that may be difficult todeduce from the listings. Theworkhorse of the chessboard inter-face program is subroutine GET-MOVE. GET-MOVE calls the KIMmonitor routine GETKEY beforedoing anything else, in order to see ifthe user has pressed the DA key(which is used when setting up a newposition) or the PC key (which clears

40

September 1979 © BYTE Publications lnc

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Figure 3: Circuit for lighting the light emitting diodes (LEDs) that indicate the computer's move. The computer moves as follows.The program lights the X and Y axis LEDs which together indicate the single square on which the piece to be moved resides. The per-son picks up the indicated piece. After the user picks up the piece, different LEDs light up that point to the square to which the pieceis to be moved. The person then places the chessman as indicated. A mistake causes the computer to emit a characteristic sound.The chip-enable line of ICl is connected to I/O (input/output) port pin PB 0 so that the LEDs may be turned off while the chess pro-gram is computing its next move.

September 1979 © BYTE Publications Inc 41

the board for a new game). If neither square by square, searching for piecesthe DA nor PC key is depressed, that were recently picked up or setGET-MOVE scans the chessboard, down. This is done by comparing the

Bfl SPEAKER

TO) CHESSBOARDCOLUMNS

) TO LEDs

TO} CHESSBOARDROWS

Figure 4: Schematic diagram of chessboard input connections for the KIM-1. If thespeaker is built into the chessboard, a 16 conductor cable is required to connect theboard to the KIM-1 application connector. Thirteen conductors control the chessboardand light emitting diodes; 3 are needed for speaker, ground, and +5 V supply. Thecable should be of sufficient length that the chessboard may be set in a convenient posi-tion for game playing.

Microchess board-status table tothe current board position, as pre-viously described. There is one im-portant exception. When the userpicks up a piece to make a move,SHOULDBEUP-FLAG is made non-zero, and the square where the pieceused to be is stored in hexadecimaladdresses FA and F9. A nonzeroSHOULDBEUP-FLAG tells sub-routine GET-MOVE that the 2squares in FA and F° should not beoccupied, even if they are shown inthe table. This is done to preventGET-MOVE from continuouslyreporting that the same piece waspicked up.

Upon exit from the subroutine, theresult of the search is stored in theaccumulator and in location UP-CLEAR-DOWN. A +1 is returned ifa piece has been picked up, a 0 if thereis no change, and a —1 if a piece wasset down. If a piece was picked up orset down, then CHANGING-SQUARE will contain the number ofthe square where the pickup or set-down occurred. Likewise, if a piecewas picked up, then CHANGING-PIECE will contain the hexadecimaldesignation of that piece as outlinedon page 3 of the Microchess player'smanual.

While GET-MOVE is scanning thechessboard, it also lights up the X andY axis LEDs that point to the squarein LIGHT-SQUARE. If SPEAKER-FLAG is nonzero, the speaker israpidly toggled to produce a hum.

Subroutine CLEAR-STACK resetsthe Microchess and the machine stackpointers back to their initial values.The subroutine is called from variousparts of the interface program to pre-vent the stacks from overflowing intoMicrochess code.

After Microchess has computedeach move, control is transferred tothe start of the interface program athexadecimal address 2000. The usermust physically move the pieces forthe computer. The piece designationand the from and to squares of thecalculated move are stored in theKIM display at hexadecimaladdresses FB, FA, and F9 respective-ly. Because of the no-operation in-structions inserted at address 03E1,the move has not been recorded in theboard-status table. Addresses 2010through 2040 of listing 2 contain code

Text continued on page 46

42 September 1979 © BYTE Publications Inc

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Listing 1: Modifications which were made to Peter Jennings' KIM-1 Microchess programto allow for the use of the electronic chessboard. Change the specified locations inmemory with the KIM monitor.

Address (Hexadecimal) New Code (Hexadecimal;

0008000A00OD000F00120033003F00B700B901AC03A703E103 E903EC

A9

FF

8D

01

17

A9

21

8D

03

17

4C

00

20

00

60

02

04

08

10

60

B1

EA

EA

EA

20

39

00

4C

00

00

Comments

Set up Port A-DDR

Set up Port B-DDR

Jump to interface programToggle, must be - 1 or zeroReturn from CLDSPMASK-TABLE (usedto read row)Return from DISPUse. SQUARE for flagDon't record moveShow all FFs(Concede defeat)

Listing 2: The Microchess to chessboard interface routine, a sort of chessboard devicehandler program. This listing is the output of an assembly with both source and hexa-decimal object code shown. It is written in a nonstandard assembly language of theauthor's own design, although most of the mnemonics are similar to the MOSTechnology standard mnemonics.

0000200020002000200020002000200020002000200020002000200020002000200020002000200020002000200020002000200020002000200020002000200020002000200020002000200020002000200020002000200020002002200420062006200A

A? 00

85 2F

A5 FA

85 2B

E6 2E

SET BIGC;0RG 2000;

COMMENT *** KIM-1 MICROCHESS TO CHESSBOARD INTERFACE ***PROGRAM. URITTEN BY JEFF TEETERS. 9/8/78

DEFINE

-BOAKll=50,

.6D-t=4F,

.BK=40,

.SF2=B2,

.SQUARE'S!,

CHANG1NG-SQUARE

CHANGING-PIECE

CLDSP-3900,

CLEAR-BUARD=180

C0UNT-FLAG=29,

DISP=9D0I,

FLASH-DISPLAY=1

FR0M-SQUARE=2A,

GETKEr = 4Alf,

G0=A203,

LlGHT-SQUARE=2B

MASK-TABLE=B?,

H0VE=4B03,

P0RT-LIGHT=2C,

P0RT-SQUARE=2D,

P0RT-A=0O17,

P0RT-B=0217,

RAND0h»=O417,

REVERSE=B202,

SPEAKER-PLAG=2E

SHOULDBEUP-FLAG

SUnCH-FLAG = 30,

TCHAN6ING-PIECE

TL'HANGING-SUUAR

TEMP=F3,

TBGbLE=33,

TUP-CLEAR-D0U

UH0vE=3103,

UP-CIEAR-D0UN

-♦"=12,

=2?,28,

0,F1F,

X ADDRESS UF PIECE I ABLE

X .BOARD LESS ONE

X ADDRESS OF USERS PIECES

Z MICROCHESS STACK POINTER

X TO SQUARE USED BY MOVE

X RETURNED BY 6ET-M0VE

X PIECE PICKED UP AT CH-SQR

2 LLEAK DISPLAI

X SET UP NEU GAME

X SEI UHLN CUUNUNG D0UN

X DISPLAY PIECE NAME IN FB

X KIM MONITOR ROUTINE

i USED UHEN UNM0VING CAPTURE

X KIM MONITOR ROUTINE

X ADDRESS OF CHESS PROGRAM

X SQUARE LIGHTED BY LEDS

X USED TO READ R0U

X ROUTINE TO UPDATE .BOARD

X USED TO BUILD 10 PORT

X

X KIM-I 1/0 PORT

2F,

-31,

E=32,

34,5,

KIM-1 1NIERVAL TIMERRUUIINE TO EXCHANGE SIDES= 1,GET-MOVE GENERATES TONE=1,SQUARES IN FA X F9 UPSET IN tXCHANGEX TEMPURARY CHANGING PIECEX IEMPORAKY CHANGING-SUUARETEMPORARY STORAGE L0CAI10NALTERNATELY LIGHTS FA i F9TEMPORARY UP-CLEAR-D0UNROUTINE TU UNMAKE MUVESTATUS OF CHANGING-SQUARERETURN VALUE OF PLUS KET

XXXXXXXXXXZXXZXXZXZXXXXXZIZZXXXXXZX7.1XX7.XZXXZXXZXXXX

XXXXXXXXXX USER MOVE COMPUTER PIECE XXXXXXXXXX

IXXXIXXXXXZXXXXXXXXXXXXZZXXXXZXXZXZXXZZIZXXIZZXIZXZX

2****4**** PICK THE PIECE UP »********J|

PICK-IT-UP:

L UAM 00

S(A SHOULDBEUP-FLAGFA

L1GHI-SQUARESPEAKER-FLAG

LDASTA

INCLOOP

XRESET FLAG

XLlGHl "PKUM SQUARE"

XS0UND OFF

44 September 1979 (E' BYTE Publications Inc

Circle 278 on inquiry card.

200A

20

6B

21

JSR GET-MOVE

XUAIT FOR PLAYER TO

2001

FO

BED

XZPICKUP PIELE.

200E

FB

ENDLOOP

200F

30

F7

BH1 PICK-11 UP

XERkOR, PItCt SET DOUN

2011

A5

27

LUA LHANGING-SQUAKE

21S P1LLE PICKED UP

2013

C5

FA

CMP Fh

XZC0RREC1 ONE?

2015

DO

F1

BNE PICK-1TUP

2017

A6

FB

LDX FB

XYES, SET TABLE ENTRY

201?

A?

CC

LOAD CC

7.110 "CC"

20IB

?5

50

STAX .BOARD

201D

£****«**** SET THE PIECE

DOUN ******♦**£

20ID

A5

F?

LDA F?

ZLIGHI TO SQUARE

20 IF

85

2B

S1A LIGHT-SQUARE

202!

E6

2E

SET

IT-DUUN: INC SPEAKER-FLAG

XHAKE NOISE

2023

LOOP

2023

20

6B

21

JSR GET-MOVE

XUAIT FOR CHANGES

2026

F0

BEQ

2027

FB

ENDLOOP

2028

A5

F?

LDA F?

XIS USER MOVEING

202A

C5

17

CMP CHANGING-SQUARE

XXCCJRRECT FIECf'

202C

DO

F3

BNE SET-IT-DUUN

202t

A5

35

LDA UP CLEAR-DOUN

ZYES

2030

10

08

IF NEGATIVE THEN

2032

A6

FB

LDX FB

ZUPOATE TABLE.(PIECE

2034

A5

27

LDA CHANGING-SOUARE

ZXSET DOUN, MOVE HAS

2036

?5

50

STAX .BOARD

ZXBEEN COMPLETED.)

2038

10

BPL

203V

08

ELSE

203A

A6

28

LUX CHANGING-PIECE

XCAPTURED PIECE HAS

203C

A?

CC

LDAtl CC

ZXBEEN PICKED UP...

203t

?5

50

STAX .BOARD

ZXUPDATE TABLE AND

2040

30

DF

BUI SET-IT-DOUN

XXUAIT FOR SET DOUN.

2042

ENDELSE

2042

nzzzzzzzzzzzzxxxzzzxzzxxzxxxxxzxxxzxxzzxxzxzxxxxxxx

2042

zzzzzzzzzxx user moue user's

FIECE XXZXXXZXXX

2042

zzzzzzzxzzzzzzzzzzxzzzzzxzxzzzzzxzxzxzxzxzxzxzxzxxxz

2042

t6

2E

INC SPEAKER-FLAG

ZMAKE NOISE

2044

A?

00

UAIT-FOR-HOVE: LDAK 00

XCLEAR UP FLAG

2046

85

2F

STA SHOULDBEUP-FLAG

2048

85

2?

SET

-COUNT: STA COUNT-FLAG

XSET COUNT FLAG

204A

20

3?

00

SET

-D1SPLAV: JSR CLDSP

ZCLEAR DISPLAY

2041)

20

6B

21

GET

-MOVE1: JSR GET-MOVE

2050

DO

41

IF ZERO THEN

2052

Z7.ZXZXXXZXZZXZXZXZXZXXXXXZX

ZXZXZXXZXXXZXZXZXX

2052

ZZZXXZZX NO CHANGE IN

BOARD XXXXXXXZ

2052

zzzzzzxzzzzzzzzzzzzzzzzzzzzzzzmzxxzxzzzzzxz

2052

It******** CHECK FOR "GO

" KEY **<*******%

2052

20

6A

IF

JSR GEIKEY

2055

C?

13

CNPtt 13

XI3=VALUE OF "GO" KEY

2057

FO

1/

BEQ GO-COUNTDOUN

205?

It******** CHECK FOR "E"

KEY «**+****»X

205?

C?

OE

CMPH OE

205B

DO

16

IF ZEKU IHEN

XUSER UANTS IU

205D

LOOP

ZXSU1TCH SIDES

205D

20

6A

IF

JSR GETKEY

2060

C?

OE

CMPtt OE

XDEBOUNCE KEYBOARD

2062

FO

BEQ

2063

F?

ENDLOOP

2064

AS

30

LDA SUI1LH-FLAG

X10GGLE FLAG

2066

4?

FF

EORK FF

2068

85

30

STA SU1TCH-FLAG

206A

20

B2

02

SUIICH-SIDES: JSK REVERSE

ZPERFORM EXCHANGE

206D

20

5D

21

JSR CLEAR-STACK

2070

4C

4C

21

60-

;0UNTD0UN: JMP START-COUNTING

2073

ENDIF

2073

X*t*****« "uO" OR "E" NOT FOUND *+***+**Z

2073

A5

2?

LDA COUNT-FLAG

XLGUNTING DOUN?

2075

FO

12

IF NOTZERO THEN

2077

C6

FB

DEC FB

XYES.

207?

A5

FB

LDA FB

207B

DO

06

IF ZERO THEN

207D

20

5D

21

JSR CLEAR-STACK

XPLAY CHESS

2080

4C

A2

03

JMP GO

2083

ENDIF

2083

A?

OF

LDAH OF

XSTILL COUNTING DOUN,

2085

65

2B

ADC LIGH1-SQUARE

XZLIUHT NEXT SQUARE.

2087

DO

BNE

2088

03

ELSE

Listing 2 continued on page 46

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September 1979 © BYTE Publications lnc 45

Listing 2 continued from page 45:

2089

All

04 17 !

208C

208C

85

2B !

208E

A5

FB !

2090

4C

4A 20 !

2093

2093

10

49 !

2095

2095

2095

2095

2095

A5

B2 !

2097

C9

C8 !

2099

F0

01 !

209B

A5

2A !

20911

C5

27 !

209F

DO

06 !

20AI

20

31 03 !

20A4

4C

44 20 !

20A7

20A7

20A7

20A7

20

6A IF !

20AA

C9

15 !

20AC

10

IC !

20AE

C9

12 !

20B0

DO

OC !

20B2

A5

FA !

20B4

10

97 !

20B6

A6

FB !

20B8

A5

1 7 |

20BA

95

50 !

2061

10

86 !

20BE

20BE

85

F3 !

20C0

A5

FB !

20C2

0A

OA !

20C4

0A

OA !

20C6

05

F3 !

20C8

85

FB !

20CA

20CA

A5

2,' !

20CC

85

2B !

20CE

85

F9 !

20D0

A5

FB !

20D2

29

IF !

20D4

85

IB !

20DA

AA

20D7

B5

50 !

20D9

B5

FA !

20DB

4C

4D 20 !

20DE

20DE

20DE

!

20BE

20DE

20DE

A5

B1 !

20E0

L9

CC !

20E2

DO

05 !

20E4

E4

B1 !

20E6

4C

6A 20 !

20E9

20E9

20E9

20

5D 21 !

20EC

A5

27 !

20tE

85

1A !

20F0

85

F9 !

20F2

8b

2B 1

20F4

20

9D 01 !

20F7

A9

01 !

20F9

85

2F !

20FB

20FB

20

6B 21 !

20FE

FO

20FF

FB

2100

2100

10

11 !

XUAITING FOR (1UVE...XXLIGHT RANDOM SQUARE

LDA? RANUGMH

ENDELSE

STA LIGHT-SQUARE

LDA FB

JMP SET-DISPLAYENDIFIF NEGATIVE THEN

xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxr.xxxxxxxxnxxx

XXXXXXXX NEU PIECE SE1 DOUN XXXIXXXX

XXXXXXXXXXXXXXXXXXXXXXXXXXXIXXXXXXXXXXXXXXXXXj>«*M**»* TAKING BACK CAPTURE? *********ZLDA .SP2

CMP* C8 XUNLI01NU PREVIOUS

IF NOTZERO THEN XI CAPTURE?LDA FR0H-S9UARECMP CHANGING-SQUAREIF ZERO THEN

JSR UHOVE X YES.

JHP UHlT-FOR-MOVEENDIFENDIF2!*********USER ADDING NEU PIECE**********?;JSR GEIKEY XUAlf FOR KEY ENTRY

CHPH 15

XXilf HEX NAME UR " + "

IF NOTZERO 1HEN

CMPM "+"

IF ZERO THEN

LDA FA

XFOUNP "+", ENTER NEU

BPL GET-H0VE1

UPIECE INTO TABLE IF

LDX IB

XXNOT IN ALREADY

LDA CHANGING-

SQUARE

STAX .BUARD

BPL UAIT-FOR-

flUVE

ENDIF

STA TEHF

2FUUND HEX DIGIT

LDA FB

U"OR" IT INTO

ASL ASL

XZPUIL NAHE.

ASL ASL

ORA TEHP

STA TB

ENDIF

LDA CHAN&ING-SQUAKt

ZBUiLU DISPLAY

STA LIGHT-SQUARE

STA F9

XUF9=SQUARE ON BOARD

LDA FB

XPU1 PIECE NAME IN

ANDti IF

URANGE

STA FB

UXFB=PIEL'E NAME

TAX

LDAX .BOARD

STA 1-A

XXXFA=TABLE EN1RY

JHP GET-MOVE 1

ENDIF

7.XXXXXXXXXXXXXXXXXXXXXXXXXXXIXZXXIXXXXXXXXXXX

XXXXXXXX PIECE PICKED UP XXXXXXXX

XIXXXXXXXXXXXXIXXXXXXXXXXXXXIXXXXXXXXXXXXZXXX

IW**M**M USER PLAY UHITE' **«*******X

LDA .SQUARE

JSEE IF USER MAKING

CHP« CC

XXTHE FIRST MOVE.

IF ZERO IHEN

INC .SQUARE

ZYES, CHANGE .SQUARE

JMP SUITCH-SIDES

HAND EXCHANGE

ENDIF

X«*+t****** gAIT FOR

CHANGt ♦*********%

JSR CLEAR-S1ACK

XLLtAK POSSIBLE JUNK

LDA CHANGING-SQUARE

STA FA

ZDISPLAT SQUARE NUrt

STA F9

STA LIGHT-SQUARE

JSR DISP

ZD1SPLAY PIECE NAME

LDA* 01

STA SHOULDBEUP-FLAG

XSET FLAG

LOOP

JSR GET-HUVE

ZAUAIT M0VE2

BEQ

ENDLOOP

2********* PIECE SET BACK

DOUN **********%

IF NEGATIVE THEN

L

sting 2 continued on page 48

Text continued from page 42:

to light the correct LEDs and modifythe board-status table as the usercompletes the computer's move. Thespeaker sounds briefly after each cor-rect step is completed. If a wrongpiece is moved or a piece is set downon a wrong square, the speaker willhum continuously to signal an error.

The logic for interpreting the user'smove starts at location 2042. IfCOUNT-FLAG is 0, the user has notyet moved. Subroutine GET-MOVEis repeatedly called from location204D in anticipation of the user'smove.

If the accumulator is 0 upon returnfrom GET-MOVE, then the boardposition remains unchanged and theuser has not made a move. GETKEYis called to see if the user has de-pressed either the GO or E key. If theE key is depressed, the Microchessroutine REVERSE is called to swapthe user and computer entries of theboard-status table. After the ex-change is completed or if the GO keyis depressed, a branch is made toSTART-COUNTING at hexadecimaladdress 214C.

Three provisions are made for adelayed return back to Microchess.COUNT-FLAG is made nonzero, acountdown is initiated by setting thedisplay to OF, and control is thentransferred back to address 204Dwhere GET-MOVE is repeatedlycalled as before.

After each return from GET-MOVE the display is decremented by1 until it equals 0. This provides anapproximate 10 second delay duringwhich the user can make a new moveor retract an old one. At the end ofthe countdown, a branch is made tothe Microchess routine GO whichcalculates the computer's next move.

If the GET-MOVE call at 204Dreturns a negative value then the userhas set down a new piece, and controlis transferred to address 2095. In anordinary game of chess, putting anew piece on the board would be con-sidered cheating. I have allowed ithere to prevent 2 possible problems.

The first problem is caused by in-decisive players who change theirminds while in the middle of a move.Suppose such a player picks up 2chessmen, as if to capture, and thendecides to set both down again. Whenthe first man is set down the programwill think that the user has completeda capture, modify the board-status

46 September 1979 '& BYTE Publications Inc

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Circle 83 on inquiry card.

BYTE September 1979 47

Listing

2 continued from page 46

2102

A5 27 !

LDA CHANGING-SQUARE

XFROM SQUARE =

2104

C5 FA !

CMP FA

XXTO SQUARE?

2106

DO 03 l

IF ZERO THEN

2108

4C 44 20 !

JHP UAIT-FOR-MOVE

XYES, NO MOVE MADE.

210B

ENDIF

210B

85 B1 !

STA .SQUARE

XNO,

2I0D

20 4B 03 I

JSR MOVE

XZRECORD MOVE,

2110

4C 4C 21

JHP START-COUNTING

HAND COUNT DOUN.

2113

ENDIF

2113

XXXXIXIIXXXZXZXXXXXXXXXIXXXXIXXXXXZXIXXIXXXXX

2113

zxxxxzxx 2'nd piece picked up ixxxzxxx

2113

XZXXIZZXXXXXZZZXXZXXXXXXXXZZXZXXXXXXXXXXXXXXX

2113

X********* UAIT FOR SET

DOUN **»*****#3I

2113

A5 27

LDA CHANGING-SQUARE

2115

85 F?

STA F?

XF?=TO SQUARE

2117

85 Bl

STA .SQUARE

211?

2-UP:

LOOP

211?

A5 33

LDA TOGGLE

ZFLASH LIGHTS FOR TO

2MB

10 06

IF NEGATIVE THEN

HAND FROM SQUARES.

211D

A5 FA

LDA FA

2I1F

E6 33

INC TOGGLE

2121

FO

BEQ

2122

04

ELSE

2123

A5 F?

LDA F?

2125

C6 33

DEC TOGGLE

2127

ENDELSE

2127

85 2B

STA LIGHT-SQUARE

212?

20 6B 21

JSR GET-MOVE

ZUAIT FOR SET DOUN

212C

FO

BEQ

212D

EB

ENDLOOP

212E

10 2?

IF NEGATIVE IHEN

2130

%********* PIECE SET DOUN *********J

2U0

A5 27

LDA CHANGING-SQUARE

2132

C5 F?

CMP F9

3X-S = TO SQUARE?

2134

FO OC

IF NOTZERO THEN

XXNOPE,

2134

C5 FA

CMP (A

Z= FROM SQUARE?

2138

DO IF

BNE ERROR-3

XXNOPE, ERROR

21U

A6 F?

LDX F?

2I3C

85 F?

STA F9

XTO X FROM SQUARES

213E

65 Bl

STA .SQUARE

ZREVERSED, SUITCH BACK

2140

H6 FA

STX FA

2142

ENDIF

2142

A5 FA

LDA FA

ZSAVE FROM SQUARE FOR

2144

85 2A

STA FROM SQUARE

ZXUSE IF UNDOING MOVE

2146

20 ?D 01

JSR DISP

ZSET .PIECE

214?

20 4B 03

JSR MOVE

ZRECORD MOVE

214C

2********* INITIALIZE COUNT DOUN *********

214C

A? 00

START-COUNTING: LDAH 00

XCLEAR FLAG

2I4E

85 2F

STA SHOULDBEUP-FLAG

2150

85 2B

STA LIGHT-SQUARE

2152

A? OF

LOAN OF

XLUAC DELAY

2154

E6 2E

INC SPEAKER-FLAG

ZSOUNII OFF

2156

4C 48 20

JHP SET-COUNT

215?

ENDIF

215?

E4 2E

ERROR-3:

INC SPEAKER-FLAG

XSOME TYPE OF" ERRUR,

215B

DO BC

BNE 2-UP

XZUAIT UNTIL CORRECTED

213D

215D

215D

215D

SUBROUTINE

CLEAR-STACK: XRESETS BOTH STACK MARKERS

2I5D

68 A8 68

PLA TAY PLA

ZSTORE RETURN ADDRESS

2160

A2 FF ?A

LDXH FF TXS

ZRESET MACHINE STACK

2143

A2 C8

LDX* C8

ZRESL1 CHESS STACK

2165

86 B2

STX .SP2

2167

48 ?8 48

PHA TYA PHA

ZSET UP RETURN

216A

60

RTS

2I6B

2148

216B

214B

! SUBROUTINE

GET-MOVE: XSCANS

CHESSBOARD

216B

! UUXHUUUllllUUUXUlXlXUUUXXXUlZlU%lXTt.U

216B

! xxxxzxxzzzz check for "da"

OR "PC" XXXXXXZXXZ

216B

! luxuuuxuxxuxxxiuvaiun

XZXZXXXXXXXZXZXZZXXXl

2I6B

20 6A IF

JSR GETKEY

216E

C? 11

CHPK 11

XI1="HA" KEY

2170

DO OB

IF ZERO THEN

2172

A2 IF

LDXH IF

ZFOUND "DELETE ALL"

Listing 2 continued on page 50

table accordingly, and proceed tocountdown. During the countdownthe second man would pop in andthere would be no way to know whatit was.

In order to prevent this, each cap-turing move is saved in theMicrochess stack. When a new pieceis set down, the stack pointer ischecked to see if the previous movewas a capture. If it was, and if thelocation of the new piece correspondsto the square where the capturingpiece used to be, then the Microchessroutine UMOVE is called to restorethe board-status table.

The second problem arises whenthe user wants to add new pieces tothe current board, or set up an entire-ly new board position. Previously theonly way to add new pieces was tostop the chess program and enter thesquare numbers manually into theboard-status table using the KIM-1monitor. This method is both incon-venient and error prone. The controllogic for the "new improved" methodoccupies hexadecimal addresses 20A7through 20DE.

After setting the new pieces down,the user simply types the piece name(its numeric designation) into thehexadecimal keyboard. The designa-tion is displayed in FB, the currentboard-status table entry in FA, andthe square where the new piece wasset down is stored in F9. If the currenttable entry is "CC" (indicating thatthe piece is not currently on theboard), the user may enter the pieceinto the table by pressing the + key.

Interpreting the User's Move

If the original call to GET-MOVEat hexadecimal address 204D returnsa positive value, it means that theuser has picked up a piece, and con-trol will transfer to address 20DE. If.SQUARE contains "CC", the Micro-chess board-status table has just beeninitialized, and the user is making thefirst move of a new game. The board-status table has been initializedassuming that the user would playBlack. A branch may be made toaddress 206A where the user andcomputer table entries are exchanged.After checking to see whether ornot the user is playing White, GET-MOVE is again called at hexadecimaladdress 20FB. If the piece is set downat a new square, the move has beencompleted and a countdown isstarted. If, after picking up a piece a

48

September 1979 © BYTE Publications Inc

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Circle 176 on inquiry card.

Integral Data Systems, Inc.

Listing

2 continued from page 48:

2174

A9

cc

LDAtt CC

2174

LOOP

2176

95

50

STAX .BOARD XFILL PIECE TABLE

217B

CA

DEX UUITH "CC"

2179

10

BPL

217A

FB

ENDLOOP

217B

30

1F

BHI JMP-TO-HAIN

217D

ENDIF

217D

C9

14

CMP* 14 X14="PC" KEY

217F

DO

21

IF ZERO THEN UIPLEASE CLEAR)

2181

20

18

00

JSR CLEAR-BOARD XSET UP NEU GAME

21S4

85

B1

STA .SQUARE XFLAG .SOUARE UITH CC

2186

A9

00

LOAN 00 ZCLEAR FLA6S

2188

85

2F

STA SHOULDBEUP-FLAG

218A

85

30

STA SUITCH-FLAG

218C

LOOF XUAIT FOR CLEAR BOARD

2I8C

A5

27

LDA CHANGING-SQUARE

218E

85

F9

STA F9 XBISPLAY BAD SQUARE

2190

85

FA

STA FA

2192

85

2B

SfA LIGHT-SQUARE

2194

20

9D

01

JSR BISP XD1SPLAT PIECE NAME

2197

20

A2

21

JSR START-SCAN

219A

DO

BNE

219B

FO

ENDLOOP

219C

20

5D

21

JNP-TO-NAIN: JSR CLEAR-STACK IRESET STACK

219F

4C

44

20

JHP UAIT-FOR-HOVE

21A2

ENDIF

21A2

muzuuuuiuxxunuumuxmnuuuuuuu

21A2

UXUlUXll START SCANNING CHESSBOARD UXXIXXXXX

2IA2

XXXIZXXXZZIIZIXZZXXZXXIXIXIZXZZIXZXZXZXIXIXUZZZXXZX

21A2

X********* SET UP PORT-LIGHT **«******2

21A2

A5

30

START-SCAN: LDA SUITCH-FLAG XSIDES EXCHANGED?

2IA4

FO

07

IF NOTZERO THEN

2IA6

A5

2B

LDA LIGHT-SQUARE XYES,

2IA8

49

77

EORII 77 ZXPL=77-"LIGHT-SGUARE

2IAA

4C

JHP

2IAB

AF

21

ELSE XNU,

2 IAD

A5

2B

LDA LIGHI-SUUARt XXPL="tlGMr-SOUARL"

21AF

ENDELSE

2IAF

85

2C

STA PORT-LIGHT

2IB1

Z********INITIALIZE U-C-D * TC-S****»***X

2IB1

A9

00

LOAD 00

2IB3

85

35

STA UP-CLEAR-UUUN

21B5

LOOP

21B5

85

32

STA fCHANGING-SQUARE

21B7

J<*********D0 MISCELLANEuUS 1/0**********2

21B7

20

IF

IF

JSR FLASH-DISPLAY IFLASH DISPLAY

21BA

A5

2E

LDA SPEAKER-FLAG

21BC

FO

03

IF NOTZERO 1HEN

21 BE

EE

00

17

INC9 PORT-A ITOGBLE SPEAKER

21C1

ENDIF

21C1

IXXXXXXXXXXXXXXXXUXXIXIXXXXXXIXXXXXXXXXIXXXX

21C1

XXXXXXXX IF SHOULDBEUP-FLAG NOf SET XXXXXXXX

21C1

XlllXllX SEE IF SQUARE IN PIECE TABLEXXIXXXXX

2IC1

zxxxxxzzzxxxxxxxzxxxxxxxxxzzxxxzixxzixxxxxzxx

21C1

A9

00

LDAtt 00 XASSUNE SQUARE OK

21C3

85

34

STA TUP-CLEAR-DOUN

21C5

A5

2F

LDA SHOULDBEUP-FLAG JIN MIDDLE OF MOVE?

21C7

FO

OA

IF NOTZERO THEN

21C9

A5

32

LDA TCHANGING-SQUAREZYES, IS SQUARE IN

21CB

C5

FA

CHP FA XXDISPLAY? IF SO

21 CD

FO

15

BEQ NOT -IN-TABLE XXPRE1EHH THAT IIS

2ICF

C5

F9

CHP F9 IXNOT IN PIECE TABLE.

2191

FO

11

BEQ NOT-IN-TABLE

21D3

ENDIF

21D3

X**********SEAKCH PIECE TABLE***********X

21D3

A2

IF

LDXIt IF

21D5

LOOP

21B5

B5

50

LDAX .BOARD

21D7

C5

32

CMP ICHANGING-SUUARt

21D9

DO

06

IF ZERU IHEN

21DB

86

31

STX TCHANGING-PIECE

21DD

E6

34

INC TUP-CLEAR-DOUN ZFOUND SQUARE

21DF

DO

05

BNE BUILD-PORTS

2tE1

ENDIF

21E1

CA

DEX

2IE2

10

BPL

Listing 2 continued on page 52

player decides to set it down on thesame square, the move is ignored.

If the GET-MOVE call at location20FB reports that a second piece hasbeen picked up, a capture is in pro-gress and control branches to location2113. FROM-SQUARE is defined asthe square from which the first chess-man is picked up. Similarly, TO-SQUARE is associated with thechessman that is picked up second.GET-MOVE is again called at hexa-decimal address 2129.

If a piece is set down on either theTO or FROM squares then the pro-gram assumes that a capture has beenmade. The Microchess routineMOVE is called to modify the board-status table, and a countdown is ini-tiated.

If a piece is set down on a squareother than the FROM or TO square,or if a third piece is picked up, abranch will be made to hexadecimaladdress 2159, and the speaker willhum to indicate an error.

Using the System

Playing the chessboard-interfacedversion of Microchess is easy. Movesare made by physically picking up thepieces and setting them down on anew square, as in a normal game ofchess with a human opponent. Theonly difference is that the opponent(the KIM-1) is unable to pick up achessman, so you have to move thepieces to the location indicated by theLEDs.

The KIM display will be all Os andthe LEDs will blink from square tosquare in a semirandom fashion whenit is your turn to move. After youmove, the KIM display will count-down from OF, and the Y axis LEDswill blink sequentially from the top tothe bottom of the board. During thiscountdown you have the option tochange your move. When the displayreaches 0, the machine will begincomputing a response, and no movescan be made until it is your turnagain.

Operating the System

The interfaced version ofMicrochess is started at address 0000,just as the unmodified Microchess.The speaker will probably hum. Tostart a new game, press the PC key.The speaker's sound will cease.Choose the White or Black pieces,and set up the board with your choice

50 September 1979 © BYTE Publications Inc

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Your energy is better spent using the results thangettirig them.

Say you're a business manager and want to projectyour annual sales. Using the calculator, pencil andpaper method, you'd lay out 12 months across asheet and fill in lines and columns of figureson products, outlets, salespeople, etc. You'dcalculate by hand the subtotals and summaryfigures. Then you'd start revising, erasingand recalculating. With VisiCalc, you simplyfill in the same figures on an electronic"sheet of paper" and let the computer dothe work.

Once your first projection is complete,you're ready to use VisiCalc's unique,powerful recalculation feature. It lets youask "What if?" examining new options andplanning for contingencies. "What if" salesdrop 20 percent in March? Just type in thesales figure. VisiCalc instantly updates aother figures affected by March sales.

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Or say you're an engineer working on a design problem and arewondering "What if that oscillation were damped by another 10percent?" Or you're working on your family's expenses andwonder "What will happen to our entertainment budget if theheating bill goes up 15 percent this winter?" VisiCalc respondsinstantly to show you all the consequences of any change.

Once you see VisiCalc in action, you'll think of many moreuses for its power. Ask your dealer for a demonstration and dis-cover how VisiCalc can help you in your professional work andpersonal life.

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Listing

21E3

21E4

21E6

21E4

21E4

21E4

21E4

2tE8

21EA

21 EC

21EE

21EF

21F1

21F3

21F3

21F5

2IF5

21F7

21F9

21FB21FD21FD21FF2202220322052207220A220C220F221122132214221 B221A221B

2 continued from page 50:Ft ! ENDL0OP

C4 34 1N0T-IN-TABLE: DEC TUP

CLEAR-MIUN XSQUAKE NO! IN .BUAKD

A5 30FO 07A5 3249 774C

F3 21AS 32

85 2D

A5 2C30 04OA OA

OA OA

2V 70EE 02 17OA

85 F3A9 012D 00 1705 F38D 00 17A5 2D29 404A 4A 4A05 2D29 OFOAOU 00 17

xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxixxxxxxxxxxxxxxxxxxx build i/o forts zmum

zzmmmzmmmxxzmmmmnmzzzz

X***»******SET UP PORT-SQUARE****»*«*«*+X

BUILD-PORTS:

LDA

SUITCH-FLAG

XSIDES EXCHANGED?

IF N01ZER0 THEN

LDA TCHANGING

-SUUARt XrES, SET PS TO

EORJ 77

ZX77-"TCH-SQUARE'

JHP

ELSE

XNO,

LDA TCHANGING

-SQUARE ZXPS="TCH-SUUARE'

ENDELSE

STA

PORT-SQUARE

)>****++*****+***PfjR| -

ft -ft ******** »***»■■* *X

LDA

PURT-LIGHI

IF POSITIVE THEN

*SL ASL

XNEGATIVE=X AXIS,

*SL ASL

XFObITIVE=Y AXIS.

ENDIF

AND*

70

INC?

PORT-B

XDI5ABLE LEDS

ASL

XLON [ TOGGLE SPEAKER

STA

TEMP

LUAtt

01

ANDfi

P0R1-A

OKA

TEMP

STAB

PURT-A

XSTORE ALL BUT COLUMN

LDA

PORT-SQUARE

AND*

40

LSR

LSR LSR

ORA

PORT-SQUARE

ANDI

OF

ASL

0RA6

PORI-A

Listing 2 continued on page 54

of color placed closest to the bottomX axis LEDs. After the chessmen arein place, the display will show all Os.If you are playing White, make youropening move. If the computer isplaying White, press the GO key.

To set up the pieces in a new con-figuration, or to continue a game thatwas halted earlier, set the chessboardup with the chessman in their desiredposition. Start the chess program asdescribed above, but instead of press-ing the PC key, press the DA key.Type in the name of each piece usingthe hexadecimal keyboard as youwould when adding a new piece.Start the play by either making amove or by pressing the GO key.

To add a new piece to the board,set the piece on the desired square.The KIM-1 display will show 3 bytesof information. The first byte will bea random piece designation (asdescribed on page 3 of the Microchessplayer's manual). The second byte isthe square that the piece is on,according to the Microchess board-status table. If the piece has been cap-tured, "CC" will be displayed. Thethird byte is the number of the square

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52 September 1979 © BYTE Publications Inc

Circle 43 on inquiry card.

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originating from Personal Software. What's more, every PersonalSoftware product is selected to give you these same benefits ofeasy availability, reliable cassettes, readable documentation, acarefully thought out user interface ... and most important,continuing challenge and enjoyment, not just once but time aftertime. If you haven't already, order your own gold cassette:MICROCHESS, by Peter Jennings, for 8K PETs, 16K APPLEs, and4K Level I and II TRS-80S $19.95

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Level I and II TRS-80s is a real timeaction game for two players, with highspeed graphics in machine language.Each player uses four keys to controlthe direction of a moving wall. Try toforce your opponent into a collisionwithout running into a wall yourself! Astrategy game at lower speeds,BLOCKADE turns into a tense game ofreflexes and coordination at fasterrates. Play on a flat or spherical courseat any of ten different speeds. You canhear SOUND EFFECTS through anearby AM radio—expect somerazzing if you lose! 14.95

GRAPHICS PACKAGE by Dan Fylstrafor 8K PETs includes programs for themost common 'practical' graphicsapplications: PLOTTER graphs bothfunctions and data to a resolution of 80by 50 points, with automatic scalingand labeling of the axes; BARPLOTproduces horizontal and vertical,segmented and labeled bar graphs;LETTER displays messages in largeblock letters, using any alphanumericor special character on the PETkeyboard; and DOODLER can be usedto create arbitrary screen patterns andsave them on cassette or in a BASIC

ELECTRIC PAINTBRUSH by KenAnderson for 4K Level land IITRS-80s:Create dazzling real time graphicsdisplays at speeds far beyond BASIC,by writing 'programs' consisting ofsimple graphics commands for amachine language interpreter.Commands let you draw lines, turncorners, change white to black, repeatprevious steps, or call other programs.The ELECTRIC PAINTBRUSH manualshows you how to create a variety offascinating artistic patterns includingthe one pictured. Show your friendssome special effects they've neverseen on a TV screen! $14.95

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WHERE TO GET IT: Look for the Personal Software^ display rack at your local computer store. For the name and address of the dealernearest you, call Personal Software at (408) 745-7841. If you don't have a dealer nearby, you can call or mail us your order with your check,money order or VISAIMaster Charge card number. For a free catalog, ask your dealer or use the reader service card at the back of thismagazine.

PERSONAL SOFTWARE INC.

592 WEDDELL DR. • SUNNYVALE, CA 94086

Circle 302 on inquiry card.

BYTE September 1979 53

Listing

2 continued from page 52:

22IE

8D

00

17

STAB PORT-A XOR IN COLUMN

2221

I***«************P0RI-B***:t*********:»***2

2221

A5

2C

LDA PORT-LIGHT

2223

18

CLC

2224

4?

80

ADCfi 80 XTOGGLE PL FLAG BIT

2224

B5

2C

STA PORT-LIGHT

2228

2?

80

ANDtt 80

222A

4A

4A

LSK LSK XSET X UR Y AXIS ANH

222C

8D

02

17

S1A0 F'ORT-B XXENABLE LEDS

222F

XXXXZXXXXXXZXXXXXXXXXXXZXXXXZXXXXXXXXXXXXXXXX

222F

XXXXXXX DID STATUS OF SQUARE CHAN6ET XXXXXXX

222F

XXXXXXl IF SO RECORD THE CHANGE XXXXX1X

222F

xxxxxxxxxxxxxxxxzxxxxxxxxxxxxxxxixxzzxxzxzxzx

222F

J*** + ***********REA[I R0U******«***«*****Z

222F

A5

2D

LDA PORT-SQUARE

2231

2?

30

ANim 30

2233

4A

4A

LSR LSR

2235

4A

4A

LSR LSR

2237

AA

l TAX

2238

65

B7

I LDAX MASK-TABLE

223A

2D

02

17

AND* PORT-B

223D

l***********CHECK FOR CHANGES************

223D

DO

04

l IF ZERO THEN

223F

A5

34

LDA TUP-CLEAR-DOUN XSQUARE OCCUPIED...

2241

10

10

BPL NEXT-SQUARE XANB IN TABLE.

2243

30

BHI

2244

04

ELSE

2245

A5

34

LDA TUP-CLEAR-DOUN ZSQUARE EHPTY...

2247

30

OA

BHI NEXT-SQUARE ZXAND NOT IN TABLE

224?

ENDELSE

224?

X**««»**F0UND A CHANGE, RECORD IT*******X

2249

85

35

STA UP-CLEAR-DOUN

224B

A5

32

LDA TCHANGING-SQUARE

224D

85

27

STA CHANGING-SQUARE

224F

A5

31

LDA TCHANGING-PIECE

2251

85

28

STA CHANGING-PIECE

2253

ZZXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXZXXXXZXXXXXXXZX

2253

XXXXXXXCHECK NEXT SQUARE OR RETURN IF ALL DONEXXXXXX

2253

XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXZXXXZXXXXXXXX

2253

E6

32

NEXT-SQUARE: INC TCHANGING-SQUARE XADD ONE TO

2255

A?

08

LDAH 08 XXTCHANGING-SBUARE

2257

25

32

AND TCHANGIN6-SQUARE

225?

OA

! ASL

225A

IB

CLC

225B

45

32

ADC TCHANGING-SQUARE XADD "CARRY"

225D

29

77

AND* 77 XHASK OUT GARBAGE

225F

85

32

S1A TCHANGING-SQUARE

2241

F0

03

BEQ RETURN

2243

4C

JHP XXXGO CHECK NEXT SQUARE

2244

B5

21

ENDLOOP

2244

A?

00

RETURN: LDA* 00

2248

85

2E

STA SPEAKER-FLAG

224A

EE

02

17

INC? PORT-B

224D

AS

35

LDA UP-CLEAR-DOUN

224F

40

RTS

2270

END OF

ASSEMBLY

upon which the new piece was setdown. Modify the first byte by typingin the correct name of the new piece.If the piece has been previously cap-tured, it may be added to the piecetable by typing the + key.

To change sides (Black to White, orvice versa), type the E key. A count-down will be initiated. Do not change

sides before the opening move of thegame; the King, Queen, and otherpieces could become incorrectlyreversed.

Conclusion

Although it may require a lot ofsolder, building the hardware isneither hard nor exacting work. As

with most projects, if it doesn't workthe first time the problem can usuallybe traced to an incorrect program,faulty wiring, or bad integrated cir-cuits. In this particular project, theprogram is already written, thewiring is easy to check, and there areonly 2 integrated circuits.

The electronic chessboard can, ofcourse, be used for activities otherthan chess. Almost any game that isplayed with an X,Y type grid can beplayed by the computer, amongthese: checkers, tic-tac-toe, and nim.

I have found that the chessboardinterface makes playing chess withthe KIM-1 much more enjoyable.Even if you lose the chess game, themethod of playing is sure to be im-pressive. ■

Editor's Note

The program described in this arti-cle was designed to be "foolproof" forthe beginning chess player. Thecountdown period for changing amove will greatly ease the frustrationoften experienced by players of com-puter games, the sinking feeling of"Oh no, I didn't mean that, andthere's no way to take back themove!" More programmers shouldpay such attention to the user inter-face of their systems.

More experienced chess playersgenerally abide by the following rule:a piece once touched by the playermust be moved, and an opponent'spiece once touched must be captured.Such users would probably wish todelete the countdown period to speedthe progress of the game.

An electronic chessboard operatingin a similar fashion appeared in thearticle "Chess 4.7 versus David Levy"by J R Douglas (December 1978BYTE, page 84). That board, con-structed by Dr David Cahlander ofControl Data Corp, uses 1 light emit-ting diode (LED) in each square of thechessboard to indicate the computer'smove, and uses magnetic switchesplaced under the squares which areactivated by the metal weights in thepieces. Controlled by a 6800 micro-processor, Cahlander's board trans-mits and receives moves to and froma remote computer on which theChess 4.7 program runs...RSS

54 September 1979 © BYTE Publications Inc

page

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Length 100 500 1,000 Length 100 500 1,000

2.5

3

3.5

4

4.55

5.56

nches

1.04

2.98

5.16

1.08

3.22

5.65

1.13

3.46

6.14

1.18

3.70

6.62

1.23

3.95

7.12

1.28

4.20

7.61

1.32

4.48

8.10

1.37

4.72

8.59

6.5 inches

1.60

5.37

9.84

7

1.66

5.63

10.37

7.5

1.73

5.89

10.91

8

1.78

6.15

11.44

8.5

1.82

6.41

11.97

9

1.87

6.76

12.51

9.5

1.92

6.93

13.04

10

1.99

7.26

13.57

ffllW

Kit #1 $7.95

Less than 2.7C/M. (#30)

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3"

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Kit #2 $19.95

Less than 2C/ft. (#30)

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Kit #3

Less than 1.7C/H. (#30)

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MICROPRO INTERNATIONAL CORPORATION1299 4th Street, San Rafael, California 94901Telephone (415) 457-8990 Telex 340388

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Programming Ouickies

A Similarity Comparator for Strings

T C O'Haver

Professor

Dept of Chemistry

University of Maryland

College Park MD 20742

The trouble with computers is thatthey have no common sense. If acomputer is directed to search a filelooking for a particular string ofcharacters, a simple typographicalerror will cause the computer toreport that no match has been found;even though there was somethingvery close in the file. The statement"If A$ = B$ THEN. . . " is takenliterally by the computer; even theslightest difference is not tolerated.

Wouldn't it be better if a computer,finding no exact match, would reportthe best match, or the 5 best matcheslisted in order of closeness of match?To do this, a routine is needed thatreturns a quantitative estimate of thesimilarity between 2 strings. That iswhat the routine illustrated here does;it computes a similarity index on ascale of 0 thru 100 percent.

Listing 1 gives a BASIC string com-parator program. The heart of theprogram is in lines 100 thru 290; lines10 thru 90 are there only to allow theroutine to be demonstrated with 2manually input strings. The funda-mental idea is simple: each characterin one string is compared to eachcharacter in the other string. This isdone so that groups of characters thatmatch are weighted more heavilythan the same number of matches ofindividual characters. This allows,for example, "POOL" and "POOR"to be rated more nearly equal than"POOL" and "POLO", even thoughthe latter 2 strings have morecharacters in common.

10

LETT = 0

20

LETP = 3

30

PRINT "FIRST WORD" ;

40

INPUT A$

50

LETA=LEN(A$)

60

PRINT "SECOND WORD" ;

70

INPUT B$

75

IF A$ = B$ THEN PRINT "EXACT MATCH

80

LETB=LEN(B$)

90

IFA>B THEN LETB = A

100

FOR M = 1 TO B

110

LETC = 0

120

FOR I = 1 TO M

130

LETK$=MID$(A$, B-M + 1,1)

140

LETL$=MID$(B$,I,1)

150

IF K$ = L$THEN LETC=C+1

160

NEXT I

170

LETC = C!P

180

LETT = T + C

190

NEXTM

200

FOR M = B+1 TO 2*B-1

210

LET C = 0

220

FOR 1 = 1 T0 2*B-M

230

LETK$=MID$(A$,I,1)

240

LETL$=MID$(B$,M-B+I,1)

250

IFK$ = L$THEN LETC = C+1

260

NEXT I

270

LETC = CtP

280

LETT = T + C

290

NEXTM

300

LETS=100*T/BtP

310

PRINT S;"%"

320

LETT = 0

330

GOTO 70

340

END

Listing 1: Listing of the similarity comparator program in Ohio Scientific Instruments8 K BASIC (a Microsoft interpreter). The up arrow indicates exponentiation.

58 September 1979 © BYTE Publications Inc

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I

BYTE September 1979 59

Circle 209 on inquiry card.

The weighting of groups ofcharacters is controlled by thevariable P defined in line 20. If P is setto a value of 1, there is no specialweighting of groups; only the totalnumber of characters in common be-tween the 2 strings is counted. If P isset greater than 1, groups areweighted more heavily, proportionalto the value of P. If P is too large,however, all but the very closestmatches result in low similarity in-dex. A value of P = 3 is a good com-promise.

Line 300 scales the index to within arange of approximately 0 thru 100percent. Two strings with no com-mon characters give 0 percent simi-larity, while 2 identical strings give100 percent similarity. Sometimes 2nonidentical, but very similar, stringswith many repeated letters (eg:"AAAAA" versus 'AAA") will give100 percent or greater than 100 per-cent similarity. This is seldom a pro-blem with practical strings.

Strings of any type can be com-pared: names, addresses, numerals,or even strings containing spaces andpunctuation. Long strings take a longtime to compare, up to severalseconds. An assembly language ver-sion should run much faster, if speedis important in your application.

The routine in listing 1 is written inOhio Scientific Instruments 8 KBASIC, Version 1, and was run on aChallenger II system. The syntax ofthe string functions, particularlyMID$, may be different in otherBASICs. However, it should be com-patible with most of the other BASICinterpreters which were developed byMicrosoft. The program also runswithout modification on an 8 KPET.H

Sample Run Comments

RUN

FIRST WORD? POOLSECOND WORD? POOLEXACT MATCH

103.1%?POOR

45.3%?COOL

45.3%? POO

45.3%? POLO

28.1%? LOOP

18.7%?PAIL

12.5%? POOL ROOM

10.4%? MAIL ROOM

1.5%? PO/OL

14.4%?0000

40.6%

OK

RUN

FIRST WORD? T.C. O'HAVER 710 HILLSBORO DR. SILVER SPRING MD.

SECOND WORD? TOM O'HAVER 710 HILLSBORO DR. SILVER SPRING MD.

82.9%? R.D. O'HAVER 710 HILLSBOROUGH RD. SILVER SPRINGS FL.

10.3%?

OK

>100% because of double letter3 letter pattern "POO" matches.

Still a 3 letter pattern.

Same match, because nonmatchingcharacters do not count.

Two 2 letter matches, "PO" and"OL", do not count as muchas one 3 letter match.

Only 2 isolated letters.

Presence of extra randomcharacter reduces match.Repeated letters resultin unexpectedly high match.

Listing 2: A sample run of the program, with comments explaining the value of similar-ity assigned.

Note: We entered this program into an Apple II computerusing the Applesoft floating point BASIC. It ran withoutmodification. The exact values of similarity computeddid sometimes differ from those given in the sample run,but only in the fourth significant digit and beyond . . .RSS

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60

September 1979 © BYTE Publications Inc

Circle 76 on inquiry card.

Unclassified Ads

Unclassified Policy

Readers who are soliciting or giving ad-vice, or who have equipment to buy, sell orswap should send in a clearly typed noticeto that effect. To be considered for publi-cation, an advertisement must be clearlynoncommercial, typed double spaced onplain white paper, contain 75 words or less,and include complete name and addressinformation.

These notices are free of charge and willbe printed one time only on a spaceavailable basis. Notices can be acceptedfrom individuals or bona fide computerusers clubs only. We can engage in nocorrespondence on these and your confir-mation of placement is appearance in anissue of BYTE.

Please note that it may take three or fourmonths for an ad to appear in themagazine.

FOR SALE: Cromemco 16 K programmable memory. 4MHz. bank select. $400 cr best offer. Will Aokel, 4860 Rolan-do CI #22. San Diego CA 92115, (714)287-6823.

EXCHANGE IDEAS: I want to talk and write to microcom-puter users who are interested in programming for farmoperations, especially in the area of Southwest Kansas,Southeastern Colorado and the Oklahoma Panhandle. I amusing an Apple II. Van Lynn Floyd, RR #1 POB 94, JohnsonKS 67855.

FOR SALE: OSI 65 V system, including: 6502 processorboard. 16 K memory board; video interface board; powersupply and case. SwTPC keyboard; single drive lloppy disk,floppy disk interface board; lloppy disk power supply andcase; all documentation (OSI and fvlOS technology); includesBASIC. Assembler, Disassembler and extended monitor. Allassembled, tested and running well. $1800 or best offer. CGum, 757 E Main St W-304 Wiss Apt. Lansdale PA 19446.(215)855-4182.

WANTED: Programs (games, graphics or just unusual pro-grams) in BASIC. Hope to establish a no cost program libraryin the near future. All material written or cassette (cassettesin TRS-80 Level 2 only) returned. Richard G Ginder, 509Southern Hills Dr, Hot Springs AR 71901.

FOR SALE: SOL-20 computer by Processor Technology with32 K. video display, cassette mass storage, Extended BASIC,IBM Seleclric lypewriter/printer, text editing and other soft-ware, complete documentation and manuals. Ideal for smallbusiness software development, 1.5 years old, $2500.Middleton Associates. 980 Yonge St Ste 404. TorontoOntario. CANADA M4W 2J9. (416) 961-5136.

FOR SALE: S-100 bus system. Cromemco Z80 processor.Byte-8 mainframe, TDL system monitor board, ACT-Ikeyboard, North Star disk and software, two 16 K static pro-grammable memory (250 ns). less 8 K of chips. Panasonicvideo monitor. Up. tested and running. For more details ofsystem, send SASE or phone (206) 456-2466 after 5 PM.Donald A Coulter, 8002 Mountain-Aire Loop SE, Olympia WA98503.

FOR SALE: Sencore Model PS163 dual trace scope in newcondition. Used less than 20 hours. Complete with twoprobes. Faclory price $895, will offer for $350. Also, SencoreModel PS148 single trace scope/vectorscope, still in faclorycarton Sacrifice, $195. R Conde. 11 Sugarbush Ln. CoramNY 11727, (516)928-4849.

FOR SALE: Digital Group TVC64 16 line 64 character upperand lower case and Greek with plug $125; COSMAC ELF withcomplete address light emitting diodes, hexadecimal thumb-wheels, audio output, automatic stepping and other features$110; hexadecimal keyboard for ELF $30; Mikos motherboard with 12 100 pin connectors in place $75; Proko PTR-IIoptical paper tape reader $50. Bert Thiel.159 W Main St,Frostburg MD 21532, (301) 689-8608 weekends and even-ings. ■

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The RS-232 standard assures maximum compat-ibility with a variety of serial devices. For ex-ample, with the AIO you can connect your Apple*to a video terminal to get 80 characters per lineinstead of 40, a modem to use time-sharingservices, or a printer for hard copy. Theserial interface is software programmable,features three handshaking lines, andincludes a rotary switch to select from7 standard baud rates. On-board firm-ware provides a powerful driverroutine so you won't need to write anysoftware to utilize the interface.

Parallel Interface.

This interface can be used to connect yourApple* to a variety of parallel printers. Theprogrammable I/O ports have enough linesto handle two printers simultaneously withhandshaking control. The users manualincludes a software listing for controllingparallel printers or, if you prefer, a par-allel driver routine is available in firm-ware as an option. And printing isonly one application for this generalpurpose parallel interface.

Two boards in one.

The AIO is the only board on the market that can interface the Appleto both serial and parallel devices. It can even do both at the sametime. That's the kind of innovative design and solid value that's beengoing into SSM products since the beginning of personal computing.The price, including PROMs and cables, is $135 in kit form, or S175assembled and tested. See the AIO at your local computerstore or contact us for more information.

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Some Musingson Hardware Design

Clayton Ellis

Rt 4, POB 86

Montrose PA 18801

The purpose of this article is to acquaintthe reader with some of the more interestingtypes of transistor-transistor logic (TTL)integrated circuits, the ease with which logicdesign can be accomplished, and to offer afew design considerations and trouble-shooting hints to stimulate the homebrewuse of digital logic.

Taking the topics in the above order, westart with a look at some of the more com-plex types of TTL chips in the "74xx"series. (We will ignore simple gates for themost part.) An example is the 7442. Thisintegrated circuit is a binary coded decimal(sometimes called BCD) to decimal decoder.What this means is that the circuit willdecode 1 line out of 10 based on a 4 bitbinary code. Figure 1 shows the pin con-nections. Regardless of what it is called,it works like this: pins 12 thru 15 are a 4 bitbinary input, pin 15 being the 1 's bit (bit 0),14 the 2's bit (bit 1), 13 the 4's bit (bit 2),and 12 the 8's bit (bit 3). Pins 1 thru 7 and 9thru 11 comprise the output pins, each pinstaying high (logic 1 or a higher level voltageof about 3 to 5 V) unless the correspondingbinary code is applied to the input. Forexample, let's say that pins 12 thru 15 are0101. In other words, 12 is at a logical low(about 0 V); 13 is at a logical high level

► 5VA

16

Vcc

O12

l

15

A

7442

2

3

14

B

34

4

5

5

6

13

C

6

7

789

9

12

D

10

1 1

GND

a

(above about 3 V, less than 5 V), etc. In thiscase, pin 6 (indicating a decimal 5) would beat a logical low level (about 0 V). All otherpins relating to decimal output numberswould be at a logical high level. Note thatonly one output pin will be low at any giventime, corresponding to the binary value ofthe input lines. "Ahh," you might ask,"what if the input pins are at some binaryvalue other than 0 thru 91" The answer iseasy; this constitutes an invalid input, and alloutput pins will stay high. Only valid deci-mal values will select an output pin.

Now let's move on to a module similar tothe 7442, the 74154. Referring to figure 2,the first apparent difference is the largernumber of pins on the 74154. This inte-grated circuit is a 4 line to 16 line decoder.Its operation is the same as the 7442, withbut two exceptions: there are now 16 validoutput lines, and provision is made to allow

24

ADDRESS

LINES

23

22

GATE

INPUTS \ 19

Vcc

A

74154

O1

2

2

3

8

3

4

4

5

C

5

6

6

_7

D

7

8

8

9

9

IP

10

II

1 1

13

12

14

Gl

13

15

G2

14

16

GND

15

17

12

n

7

\0UTPUTS

Figure J: Pin connections for a 7442 TTLbinary coded decimal to decimal converter.

Figure 2: Pin connections for a 74154 TTL4 line to 16 line decoder.

62 September 1979 © BYTE Publications Inc

DATA'SELECT

STROBE

Figure 3: Pin connections for a 74750 TTL1 of16 line data selector.

two extra inputs to gate the individual lineselected. Pins 18 and 19 perform this gatingfunction. An example of use of this extragating feature might look like this: pins 20thru 23 might contain the binary equivalentof a decimal 14, pin 19 being low and pin 18alternating from high to low (a periodicclock pulse.) The end result is that pin 16(corresponding to line 14) will also periodi-cally alternate high and low in following thesignal on pin 18. The data at pin 18 is trans-ferred to pin 14. If the binary code on pins20 thru 23 were now changed to a decimal7, then line 7 (pin 8) would follow the dataon pin 18. We select one of 16 outputs for asignal applied to the gates. Now, if we couldjust have a binary controlled switch to select1 of 16 inputs. Let's look at the 74150.Figure 3 shows the pinout of this one.This time there are 21 input pins and only 1output pin.

Let's see how this one works. Binaryinput is on the 4 lines of pins 11 and 1 3 thru15. Let's say a binary value of 12 is present.This selects the number 12 input line (pin19) and transfers the level of this line, be itsteady, high, low or some alternating clocksignal, to pin 10, the output line. Notice,though, that in order for the data to betransferred, pin 9 (the strobe input) alsomust be low. A high level on the strobeinput prevents any data transfer from anyinput. This feature is used to allow datatransfer only at selected intervals, such as

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Circle 10 on inquiry card.

September 1979 © BYTE Publications Inc 63

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64 BYTE September 1979

Circle 210 on inquiry card.

Figure 4: A data selectorto sample each of 16 linessequentially. It looks good,but it doesn't work. Aneglected inversion in logiclevels and thinking is thedemon.

0 I 2 3 4 5 6 7 8 9 10 II 12 13 14 1574154 Vcc

A B C D GND

o-

23

12

22

21

20

12

► 5V

rh

+ 5V

Figure 5: Another approach to the problemin figure 4. This approach has a much lowerparts count, so it is much easier to wire andit works.

0A QB QCB 7493A

A(CLOCK) „

QDVcc

m

when the input would contain valid data, orwhen the output is useful only at specificintervals.

Now that we have taken a look at a fewof the more involved logic blocks, let's lookat how easy it is to design the somewhatmore complicated circuits using the simpleTTL blocks in conjunction with one or moreof the above type of logic blocks.

If we want to build a sequencing deviceto look at a number of incoming lines, andif we are to use a given clock signal to coor-dinate all this, we can use the logic circuitin figure 4. A very simple and straight-forward circuit, right? Not quite. Let's takea second look. All the inputs but the oneselected by the 74154 are going to be en-abled at one time. The selected pin goes low,remember? By this time, if not before, youprobably recalled the look we just took atthe 74150 and are wondering why we didnot use it. Figure 5 shows the circuit usingthe 74150. The foregoing just illustrates agood point (and one to keep in mind when-ever you undertake any logic design). There

o-

o-

O-O-O-

o-o-

Vcc74I50

OUT

C^

-o

1

OA QB 0C 0DB V

749 3 A

A(CLOCK)

Rl R2 GND

September 1979 © BYTE Publications lnc 65

Get circuit requirements down on paper in block form.Break each block down into required logic.

Use the most integrated block available for each function as in the example offigure 5 unless the cost of such a module is much higher than two or possiblythree less intricate ones.

Don't go overboard with smaller blocks. This increases the density and complexityof interconnection, greatly increases the chances of errors and reduces systemreliability.

Cross-check all designs, as you may have redundantly developed the same signalline. Sometimes most of one segment of a circuit can be eliminated with an inver-ter or small amount of additional gating.

If possible, have a friend familiar with digital logic go over the layout. Your friendcan sometimes suggest circuit reductions that you missed simply because youwere thinking one way while your friend used a different approach. The samereview may even spot an error in the logic. With all those inversions, gating, etc, itis easy to do. Spotting an error at this stage can save hours at the breadboard stage.

Table 1: Approach tofinding the simplest logiccircuit for a given function.

are many ways to accomplish a specific func-tion. So many, in fact, that large companieswho do digital logic design in large quantitiesinvariably use some form of computer aidedlogic design. The homebrew enthusiast ob-viously can't go that far, but the approachsummarized in table 1 usually works fairlywell.

Timing

Another good point to keep in mind is tothink time (not in terms of how long it takesto design a circuit, or build it, but time rela-tionships in the circuitry itself). This brings

us back to a term, clock, that we have beenusing freely up to now. We all know that aclock is merely a line, usually derived from asquare wave oscillator, right? This line isthen used to coordinate all necessary gating,shifting, setting and resetting, etc, that goeson within the circuitry itself, right? Well,that is part of it, but who said it had to be asingle line? Some computers use a numberof clock lines, perhaps as many as 8 or 10.The only thing these multiple clock lineshave in common is that they are usually allderived from the same oscillator and maybe individually gated on or off, counted,decoded or subjected to any other valid logicmanipulation.

Figure 6 shows a typical clock circuitdetailing some of these practices. As youcan readily see, almost any combination ofclock times can be selected, and the flipflops can be extended as far as needed toselect a single clock pulse or a repetitiveseries of clock pulses. The point to remem-ber is that all pulses are derived from thesame clock and each pulse on any line willbe of the same duration as any other clockpulse. The single clock pulse shown online C of the timing chart in figure 6 willstart at the same time as the fourth clock

TOGGLE FLIP FLOPS DIVIDE FREQUENCY BY 2

Figure 6: A hypotheticalclock circuit to give twodifferent phases (lines Aand B) at two differentrepetition rates. Lines Aand B are at 1 j2 the clockrate. Line C is at 1/8 theclock rate with the samepulse duration.

-^>c—[u>c-

T Q

FF I

T 0

FF2

{>

T Q

FF3

T 0

FF4

^>A

Ob

^y

-Oc

CLOCK

~L

~L

~L

r

n

CLOCK* FFI

_TL

CLOCK.FFI

CLOCK'FFI • FF2 "FF3

66 September 1979 © BYTE Publications Inc

pulse on line A, and the duration will beidentical.

There is one fly in the ointment at thispoint. I just noted that the two clock pulseswould start at the exact same time. That isnot quite true, however, and depending onhow fast the clock is running, and exactlywhat is being gated, this may or may not bea problem.

In an actual circuit, the clock pulse online A would go positive slightly ahead ofthe pulse on line C. This is due to the delay(called propagation delay) across each flipflop encountered by the leading edge of thepulse. This delay is on the order of nano-seconds for each gate encountered. Let usassume an arbitrary 5 ns delay for each gate.Then the delay from the input of FF1 to theoutput of the AND gate driving line A wouldbe 10 ns. This is 5 ns for FF1 and 5 ns forthe AND gate. The delay from the input toFF1 to the output of the AND gate drivingline C would be not 10 ns, but 20 ns: 5 nsfor each of the three flip flops and 5 ns forthe AND gate. The pulse on line C wouldactually start 10 ns after the one of line A.This will also make a difference in the dura-tion of the pulse on each line; as the pluslevel arriving later than the clock pulse atthe input to the AND gate determines whenthe output of the AND gate goes positive.However, the trailing edge of the clock pulseinput determines when the AND gate outputgoes negative.

This, in effect, shortens the duration ofthe pulse on the output line by a time (innanoseconds) determined by the variouspropagation delays. If the clock frequencyof the circuit is on the order of tens or hun-dreds of kilohertz, then a delay of tens of

nanoseconds would be of little consequence;but if the clock frequency of the circuit issomething like 20 or 25 MHz, the delay canbecome a thorn in the side of the designer.This holds true for all data and control lineswe well as clock lines.

This propagation delay can be used to anadvantage too. Figure 7 illustrates using thisdelay to generate a narrow pulse. Here thepositive going (leading) edge of the input isapplied to an AND gate, but the negativegoing (trailing) edge of the inverted versionapplied to the other leg of the AND gate isdelayed by the total of the propagationdelay across the three inverter blocks. Theresultant output is a narrow pulse equal induration to the delay across the inverters.This method of generating a pulse is onlyuseful in cases where we don't care exactlyhow long the pulse lasts since gates andinverters are subject to manufacturingvariations.

To satisfy the rather picky individual orvery high speed circuit, I have to say alsothat the output pulse is not only derivedfrom the inverter delay, but is delayed fromthe leading edge of the original pulse by theamount of the delay across the AND gateitself. Figure 8 illustrates this. The short de-lays shown on waveform C are due to theAND gate propagation delay. For most situa-tions, this is carrying propagation delayaccounting to extremes, but in certain highspeed circuits each delay may have to beaccounted for. If 20 or 30 gates are involved,the cumulative effects add up rather fast.

Also to be considered is the capacitiveeffect of the interconnection lines: the dis-tributed and stray capacitance which are inparallel with the output of each gate addslightly to delay times. It takes a finiteamount of time to charge this capacitance at

Figure 7: A pulse generator for nanosecondrange pulses. Pulse length Is determined bythe propagation time through the gatesbetween the input and point B. More sophis-ticated methods are required if an accuratepulse length is required.

Figure 8: A magnified view of the pulseshown in figure 7. The output pulse is de-layed by the propagation time of the A NDgate. This time varies but is typically about10 ns for normal transistor-transistor logic,less for the high speed and Schottky versionand more for the low power integratedcircuits.

September 1979 © BYTE Publications Inc 67

each gate turn on, and the gate will notswitch until a certain voltage input level isreached. All of which leads right into the lastsubject I'd like to touch on. How do you seeall this in an actual circuit? Believe me whenI say that it takes a good oscilloscope. Tohave a good display in the tens of nano-seconds range, it takes an oscilloscope witha bandwidth of at least 60 to 100 MHz.Does this mean that anyone without suchan oscilloscope can't do much with higherspeed TTL? Not necessarily. Remember wesaid that propagation delay only becomesa problem at high speeds and multiple gatedelays. There are a number of ways aroundthis. One is to keep clock frequencies and

data changes as slow as possible. Don't usea fast clock or data encoding just for thesake of speed, run it as fast as necessaryand no faster. If you can tolerate a slowclock speed, use it. Another method is totry and bring each data line that is to begated with another line through the samenumber of gates as the line it is to be gatedwith. In other words, if one line originatesat about the same source as another that itis to be gated with, but passes through 9levels of gating, and the other line passesthrough 3, the delays at high speeds can bea problem. This could be compensated forby changing the way the lines are gated tobring the delays in each line closer to the

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68 September 1979 © BYTE Publications Inc

Circle 75 on inquiry card.

same length. Another help in extreme casesis to run the line with the lesser number ofgates through several pairs of inverters. Thisintroduces a delay to compensate for thedelay in the other line. In other words,make the faster line wait for the slower one.An even better solution is to design yourcircuits "synchronously" so that only oneclock source ever changes the state of a flipflop or memory cell.

As to seeing these problems on the sloweroscilloscopes, there are several hints that willhelp. Very little serious work with timingrelationships can be undertaken without adual trace capability (although a good dealcan be done otherwise with TTL with justa single trace scope). Even with a dual traceoscilloscope, the fastest sweep speed maynot reveal a lot of timing detail if not set upcorrectly and the alternate sweeps may notbe time correlated without a common syn-chronization signal. A number of tests canbe made with a single trace oscilloscope if ithas provisions for external synchronization.

In general, synchronize the oscilloscopesweep as far ahead in time as is realistic forthe signals in question, in order to allowtime for the sweep to start before the pulseactually arrives. It goes without saying thatthe synchronization signal must be commonto all signals being examined.

If you still can't see any difference, tryestimating the approximate delay for eachline from source to common logic block.Most logic handbooks list typical delays forintegrated circuits. If the problem is in acounter circuit of some type which counts"up," the count for a given sequence willusually be too high in value if delay prob-lems are the cause. Rarely will the count ofan "up" counter be too low, as the usualsituation is advancing the counter by an ex-tra pulse generated by mismatched delays,especially if a lot of exclusive ORing is beingdone. The situation where early turn off ordisabling of the counter causes a missedcount is quite unlikely, mainly because thedelay is of a much shorter duration than thepulses being counted.

These problems are all good to be awareof, but don't let them deter you from start-ing that project you were thinking about.You may go a long time before you see oneof the problems described. Don't let thelack of a superb oscilloscope deter youeither. A lot of very intricate and fast digi-tal circuitry is being built every day withnothing more than a single trace I MHz ACcoupled oscilloscope. With a little experi-ence, you can tell a great deal about a givenTTL circuit with one of these inexpensiveoscilloscopes."

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September 1979 © BYTE Publications Inc

69

A Low-Speed Analog-to-DigitalConverter for the Apple II

Richard C Hallgren

Assistant Professor

Michigan State University

College of Osteopathic Medicine,

Dept of Biomechanics

East Lansing MI 48824

The development of micropro-cessor-based computer systems hasprogressed to the point where it isnow practical to utilize these systemsin a scientific or laboratory applica-tion. To be useful in a scientific appli-cation the computer must have thecapability o/ converting analogsignals to digital signals. Very fewhome computers have this capability.Certainly it is a straightforward taskto design an analog-to-digital con-verter (ADC), but the real problemlies in connecting the converter to thecomputer.

The Apple II computer, with 8peripheral-board connectors on themother board, makes the job ofdesigning and implementing specialinterfaces (such as the ADC) rela-tively easy. The peripheral-boardconnectors give the hardwaredesigner access to all address, data,and control lines. In addition all con-trol, address, and data lines havebeen buffered, and certain addressbits have been decoded to give adevice select (DS) signal. Whatthis means is that when a specificrange of address locations is accessed,the DS line will give a low outputsignal. Since the peripheral-boardconnectors are on the main computer

About the Author

Richard Hallgren is an Assistant Professor inthe Dept of Biomechanics at Michigan StateUniversity. He is working on the application ofmicroprocessor-based systems in scientificresearch.

IC1

MC14028

16

a

IC2

MC14049

1

B

IC3

SN7427

14

7

IC4

MC14013

14

7

IC5

MC14433

24

13

IC6

AD580

—

—

IC7

MC14503

16

8

IC8

MC14503

16

a

IC9

DM7432

14

7

Number Type +5V GND -5V

12

Table 1: Voltages which must be suppliedto integrated circuits in figure 1 foroperating power.

board, the finished interface boardwill be inside the computer and willbe able to use the computer's powersupply. Because of these character-istics, turning the Apple II into a real-time data analyzer becomes a matterof designing an analog-to-digital con-verter circuit, and control logic tomeet the need of the application.

Many of the applications that I hadin mind were to be of a low-speednature (eg: monitoring the tempera-ture of experimental animals inmedical physiology laboratories,analyzing the results of elec-trophoretic analysis). Therefore, alow-speed analog-to-digital converterbuilt around the Motorola MC14433integrated circuit seemed to be a costeffective approach. I was inspired bySteve Ciarcia's article, "On a TestEquipment Diet? Try an 8 ChannelDVM Cocktail!" (December 1977BYTE, page 76).

The left section of figure 1 showsthe analog-to-digital converter cir-

cuitry. All data and status lines to thecomputer are isolated through theMC14503 3-state buffers (IC7 andIC8). The MC14433 (IC5) is allowedto convert continuously at a rate ofapproximately 15 conversions persecond. This means that if the datatransfer to memory starts immedi-ately after the conversion ends, theApple II can easily decode and storethe data from one conversion beforeanother conversion occurs. IC4, con-figured as an RS flip-flop that is in-itially reset by the computer, is set bythe MC14433 after an analog-to-digital conversion has been com-pleted. When the computer sensesthis change in status, it starts thedecoding and data transfer process.IC6 is an AD 580 used to provide astable reference voltage to theMC14433.

The right section of figure 1 showsthe control logic that is necessary tocoordinate the transfer of data to thecomputer, and control signals fromthe computer. The circuit is designedso that the peripheral card resides inI/O (input/output) slot 7 on theApple II mother board. The deviceselect signal will go low wheneverhexadecimal memory locations C0F0thru COFF are addressed. The least

Text continued on page 74

Figure 1: Schematic diagram of analog-to-digital-conversion circuit and associatedcontrol-logic circuitry. The analog-to-digital (A/D) converter is shown on theleft side, the control logic on the rightside. »_

70 September 1979 © BYTE Publications Inc

ANALOG-TO-DIGITAL CONVERSION CIRCUIT

^—| 0-1.999■^ 1 VOLTS

D7 D6

D5 04 D3 D2 Dl DO

R/W DS

September 1979 © BYTE Publications lnc 71

Circle 379 on inquiry card.

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( CALL FROM "\V^ BASIC ROUTINE^/

SAVE A,X,ANDY REGISTERS

INITIALIZEDATA STORAGELOCATION

YES

(RETURN TO ^BASIC ROUTINE J

INPUT DIGITCODE AND DIGIT

YES

STORE DIGIT

YES

Figure 2: Flowchart of the machine language subroutine which takes samples from theanalog-to-digital converter. This code is written for the 6502 processor used in theApple II.

72

September 1979 © BYTE Publications Inc

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BYTE September 1979 73

Address Instruction Op Code Operand Comments

4000

4003

4006

4009

400A

400C

400E

4010

4012

4014

4016

4019

401B

401E

401F

4022

4024

4026

4029

402C

402F

4030

4031

4032

4033

4036

4D37

4038

4039

403A

403B

403C

403D

403E

403 F

4040

4043

4046

4048

404A

404C

404F

4052

4054

4056

4058

405B

405 D

405F

4061

4062

4064

4066

4068

4069

406B

406E

4071

4073

4075

4077

407A

407C

407E

4080

4081

4083

4085

4087

4088

408A

408D

4090

4092

4094

4096

4099

409B

409D

409 F

40A0

AD B08E B18C B208

A2 00A9 0085 0AA9 4A85 0BA9 008D A0A9 4E8D A178

AD A1C5 OBDO OBAD BOAE B1AC B2286058EA

4C 1EEAEAEAEAEAEAEAEAEAEA

8D F2AD F129 80C9 80DO F7AD FO8D A229 80C9 80DO F4AD A229 OF81 OA

A4 OAC8

84 OA

DO 05

A4 OBC8

84 OB

AD FO

8D A2

29 40

C9 40

DO F4

AD A2

29 OF

81 OA

A4 OAC8

84 OA

DO 05

A4 OBC8

84 OB

AD FO

8D A2

29 20

C9 20

DO F4

AD A2

29 OF

81 OA

A4 OAC8

84 OA

49 LDA49 STX49 STYPHPLDXLDASTALDASTALDA49 STALDA49 STASEI49 LDACMPBNE49 LDA49 LDX49 LDYPLPRTSCLINOP40 JMPNOPNOPNOPNOPNOPNOPNOPNOPNOPNOPCO STACO LDAANDCMPBNECO LDA49 STAANDCMPBNE49 LDAANDSTA

LDYINYSTYBNELDYINYSTYCO LDA49 STAANDCMPBNE49 LDAANDSTALDYINYSTYBNELDYINYSTYCO LDA49 STAANDCMPBNE49 LDAANDSTALDYINYSTY

$49 BO

$49B1 Save registers

$49B2

#$00

#$00

$0A Starting location of data storage

#$4A

$0B

#$00

$49A0 Final location of data storage

#$4E

$49A1

Disable interrupt$49A1$0B

$4031 Have all data locations been filled?$49B0$49B1$49B2

$401E

$C0F2

$C0F1

#$80

#$80

$4043

$C0F0

$49A2

#$80

$0A

$0A

$406B

$0B

$0B

$C0F0

$49A2

#$40

#$40

$406B

$49A2

#$0F

($0A,X)

$0A

$0A

$408A

$0B

$0B

$C0F0

$49A2

#$20

#$20

$408A

$49A2

#$0F

($0A,X)

$0A

$0A

Enable Interrupt

Start A/D conversion

A/D conversion finished?

Input data

Temporary data storage

#$80 Check for first digit (MSD)

$404C

$49A2

#$0F

($0A,X)

Peel off digit code leaving dataStore data

Increment lower 8 bits of data storageCarry out to upper 8 bits?Increment upper 8 bits of data storageInput data

Check for second digit

Peel off digit code leaving dataStore data

Increment lower 8 bits of data storage

Carry out to upper 8 bits?

Increment upper 8 bits of data storage

Input data

Check for third digit

Peel off digit code leaving dataStore data

Increment lower 8 bits of data storage

Listing 1: The machine languagesubroutine for collecting data from theanalog-to-digital converter, here shown inassembly language format. Memory loca-tions 03FE and 03FF contain the hex-adecimal interrupt jump vector 4040,which is the entry point of this routine.

Text continued from page 70:

significant 4 bits of the address aredecoded by ICl and are used for onboard addressing. Performing a storeaccumulator (STA) operation to loca-tion C0F2 causes the SC (start conver-sion) line to go high and resets theflip-flop IC4. Performing a LDA(load accumulator) from hexadecimallocation C0F1 transfers the end ofconversion (EOC) and overrange(OR) status data into the computer.Performing a LDA from locationC0F0 transfers the digit-select codeand the binary coded decimal (BCD)value of the particular digit selectedinto the computer.

The software portion of the analog-to-digital converter project is dividedinto 2 parts:

• A machine language routine toprovide high-speed transfer ofdata from the MC14433 to thecomputer memory.

• A BASIC routine written inApplesoft floating-point BASIC totake the data in memory and for-mat it into a voltage that can bedisplayed as a function of timewith the high-resolution graphicsroutine.

Since the Apple II does not have aninternal real-time clock, I decided touse the interrupt request line (IRQ)as an input for an external clock. Theadvantage to this is that a calibratedpulse generator can be used to deter-mine the sampling rate. If desired, thecomputer can perform other tasksbetween samples. Knowing wheneach sample was taken makes it possi-ble to display the data as a function oftime with the high-resolutiongraphics routine. Since the Apple IIhigh-resolution graphics allows thedisplay of 256 points I decided tostore 256 points in memory beforedisplaying the data, but there is noreason why the data could not bedisplayed as it is taken. Figure 2shows the flowchart of the machinelanguage program, and listing 1

74 September 1979 © BYTE Publications Inc

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Circle 221 on inquiry card.

BYTE September 1979

75

Carry out to upper 8 bits?

Increment upper 8 bits of data storage

Input data

Check for LSD (least significant digit)

Peel off digit code leaving dataStore data

Increment lower 8 bits of data storage

Carry out to upper 8 bits?

Increment upper 8 bits of data storage

Return from interrupt

Listing2: Program in Applesoft floating point BASIC which calls the machine languageroutine of listing 1 and then formats and displays the data received, using the high-resolution graphics capability of the Apple II.

40A2

DO

05

BNE

$40A9

40A4

A4

OB

LDY

SOB

40A6

C8

INY

40A7

84

OB

STY

SOB

40A9

AD

F0

CO LDA

SCOFO

40AC

8D

A2

49 STA

S49A2

40AF

29

10

AND

#$10

40B1

C9

10

CMP

#$10

40B3

DO

F4

BNE

$40A9

40B5

AD

A2

49 LDA

S49A2

40B8

29

OF

AND

#$0F

40BA

81

0A

STA

($0A,X)

40BC

A4

0A

LDY

$0A

40BE

C8

INY

40BF

84

0A

STY

$0A

40C1

DO

05

BNE

$40C8

40C3

A4

0B

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$0B

40C5

C8

INY

40C6

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SOB

40C8

A5

45

LDA

$45

40CA

40

RTI

Program

100 DIM Z (300)

101 HOME

102 GOTO 1000

110 CALL 16384

111 HOME: VTAB 24

112 PRINT "THE DIGITIZED DATA IS

BEING FORMATTED FOR PLOTING"

113 X= 18944

115 FORJ = 0TO255

120 V1 = PEEK(X)

122 V2=PEEK(X + 1)

124 V3=PEEK(X + 2)

126 V4 = PEEK(X + 3)

128 X = X + 4

130 IF V1 > 7 THEN V1 = 0

132 IF V1 = OTHEN GOTO 140

134 V1 = 1

140 V$ = STR$ (V1) + STR$ (V2) +

STR$ (V3) + STR$ (V4)

150 Z(J) = VAL(V$)/1000

160 NEXT J

200 HGR: HCOLOR = 3

202 HPLOT 20,0 TO 20,150

204 HPLOT TO 279,150

208 HPLOT 18,0 TO 22,0

210 HPLOT 18,10 TO 22,10

212 HPLOT 18,20 TO 22,20

214 HPLOT 18,30 TO 22,30

216 HPLOT 18,40 TO 22,40

218 HPLOT 18,50 TO 22,50

220 HPLOT 18,60 TO 22,60

222 HPLOT 18,70 TO 22,70

224 HPLOT 18,80 TO 22,80

226 HPLOT 18,90 TO 22,90

228 HPLOT 18,100 TO 22,100

230 HPLOT 18,110 TO 22,110

232 HPLOT 18,120 TO 22,120

234 HPLOT 18,130 TO 22,130

236 HPLOT 18,140 TO 22,140

238 HPLOT 18,150 TO 22,150

240 HPLOT 4,47 TO 4,53

242 HPLOT 7,53

246 HPLOT 10,47 TO 10,53

248 HPLOT TO 14,53

250 HPLOT TO 14,47

252 HPLOT TO 10,47

260 HPLOT 7,103

262 HPLOT 14,97 TO 10,97

Comments

Machine language routine

Starting address of data

Get first digit (MSD)Get second digitGet third digitGet fourth digit (LSD)

Decode MSD

Convert digits into voltage XXX.X

High-resolution graphics

Plot X-Y axis

Figure 3: Flowchart of the BASIC pro-gram which calls the machine languagesubroutine, formats the data obtainedfrom the analog-to-digital converter, anddisplays it using high-resolution graphics.

( start J

CALL MACHINELANGUAGE ROUTINE

INITIALIZEDATA STORAGELOCATION

GET 4 DIGITS

FORMAT INTOVOLTAGE

PLOT X, Y AXIS

PLOT VOLTAGESAMPLES

YES

f STOP J

Listing 2 continued on page 78

shows the coded program with com-ments.

Upon entering the subroutine, allof the necessary registers are saved toenable a successful return fromsubroutine. The first thing thathappens is that the end of conversionflip-flop is reset and the programloops until the MC14433 completesthe next conversion and sets the flip-flop. The program then samples thedata lines and decides whether or notthe data represents the most signifi-cant piece of data. If it does not, theprogram continues to sample the datalines until the most significant pieceof data has been obtained. Thisdatum is then stored in memory, thememory storage locations are in-

76 September 1979 © BYTE Publications Inc

w^^JutMyf^fH

(Mud

announcement I. The first eight Personal'rograms8from Aladdin Automation arewaiting for you now at your neighborhoodomputer retailer or direct from Aladdin.

low you can get your full share of Aladdinlagic in every one of these Personal'rograms8:

Math-Tor-Mind A delightful,educational learning experiencefor your pre-school child. Watchle smile on your child's face as a correctnswer makes the mathematician smile on the:reen before you. A nursery song also serves3 a reward for learning elementary additionnd subtraction. With Aladdin's Math-Ter-1inds your child's pathway to learning will bejn-filled . . . for both of you. Math-Ter-Mind8.ne first release from the Aladdin Education®eries. (nursery song currently available onlyn Apple II"" program)

Lunar Lander In a controlleddescent, you're |ust seconds awayfrom your first landing on the cold.nbidding surface of the moon. As youavigate your delicate spacecraft downward tole safety of Moonbase. you must be ever/atchful of the dangers rising to meet you withach passing moment: a fuel level fastpproaching zero; deadly meteor showers thatome from any direction, at any time; sheer-jced rock cliffs and rough terrain; choosing^e correct landing pattern and rate of descent.Jaddin's Lunar Lander. Your chance to reachut and touch the stars . . . without leaving theafety and comfort of your own chair. The first?lease from the Aladdin Simulation8 Series.

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Mastermind A challenging gameof intrigue, centuries old, that willgive you full chance to test yourpowers of logic, deduction and reason. Andtest them you will, as you try and solve thecomputer's puzzle, using clues as they'reprovided one-by-one. You control the degree ofdifficulty in this classic Personal Program8 thatoffers one simple, yet all-consuming challenge;beat the Mastermind in a direct, one-on-onebattle of wits. Aladdin's Mastermind. The firstrelease from the Aladdin Old Favorites8 Series.

Tic-Tac-Toe Five different levelsof difficulty allow a person of anyage or skill to take part in thisrelaxing, enjoyable game that can act as alearning tool, as well. Level I. for example, issuitable for children and is excellent also forteaching simple mathematics. The computerplays just about perfectly at Level V. Justabout, that is. so go ahead and take your bestshot. See if you can beat the computer in thistraditional favorite of young and old alike.Tic-Tac-Toe. Another first release from theAladdin Old Favorites"' Series.

Jungle Island8 Shipwrecked in araging storm at sea, miraculouslyyou survive only to find yourselfstranded on a seemingly deserted jungleisland. Without food, water or supplies of anykind, you begin to try and find your way tosafety. The computer will be your eyes andears as you explore your jungle island and allthe mysteries and dangers that lie in wait foryou. Jungle Island8 A captivating firstrelease from the Aladdin Adventure8 Series.

Stix- Aladdin's Stix'" can beplayed with 2 to 5 piles of st icksand between 1 and 1 9 sticks ineach pile. The object: to be the one to pick upthe last stick. Sounds simple? Yes. but you'replaying against the computer. Take heart,though, because you can control the degree ofdifficulty in this update of the ancient game ofNim. Stix8. Another first release from theAladdin Old Favorites8 Series.

Super Pro Football8 Here's yourchance to be more than just anarmchair quarterback. WithAladdin's Super Pro Football"' you can replayany Super Bowl game, from the first, betweenGreen Bay and Oakland, to last year's classicvictory by Pittsburgh over Dallas. For once youcan turn back the clock and go for that one bigplay that made the difference between victoryand defeat in pro football's biggest game of all.Super Pro Football8. The first exciting releasefrom the Aladdin Super Pro8 Series

Visit your neighborhood computer retailer orcontact Aladdin direct to get your full share ofthe magic in Announcement I. the first eightPersonal Programs"" from Aladdin Automation.

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3420 Kenyon Street, Ste. 131, San Diego, CA 92110

opyright 1978 by Aladdin Automation

Design and copy by Campbell Marsh Graphic Communications

Listing 2 continued:

264

HPLOT TO 10,100

266

HPLOT TO 14,100

268

HPLOT TO 14,103

270

HPLOT TO 10,103

272

HPLOT 14,147 TO 10,147

274

HPLOT TO 10,153

276

HPLOT TO 14,153

278

HPLOT TO 14,147

280

HPLOT 30,148 TO 30,152

281

HPLOT 40,148 TO 40,152: HPLOT

50,148 TO 50,152

282

HPLOT 60,148 TO 60,152: HPLOT

70,148 TO 70,152

283

HPLOT 80,148 TO 80,152: HPLOT

90,148 TO 90,152

284

HPLOT 100,148 TO 100,152: HPLOT

110,148 TO 110,152

285

HPLOT 120,148 TO 120,152: HPLOT

130,148 TO 130,152

286

HPLOT 140,148 TO 140,152: HPLOT

150,148 TO 150,152

287

HPLOT 160,148 TO 160,152: HPLOT

170,148 TO 170,152

288

HPLOT 180,148 TO 180,152: HPLOT

190,148 TO 190,152

289

HPLOT 200,148 TO 200,152: HPLOT

210,148 TO 210,152

290

HPLOT 220,148 TO 220,152: HPLOT

230,148 TO 230,152

291

HPLOT 240,148 TO 240,152: HPLOT

250,148 TO 250,152

292

HPLOT 260,148 TO 260,152: HPLOT

270,148 TO 270,152

300

FOR J = 0 TO 255

310

HPLOT J + 20,150 - (Z(J) * 100)

320

NEXT J

1000

PRINT "PRESS RETURN TO START A/D

1010

K = PEEK( - 16384)

1012

POKE - 16368,0

1014

IFK > 127 THEN GOTO 1020

1016

GOTO 1010

1020

TEXT

1022

HOME

1024

VTAB 24

1026

PRINT "256 DATA POINTS ARE

BEING DIGITIZED"

1028

GOTO 110

1099

END

Photo 1: High-resolution display of a 0.05Hz sine wave signal which has beendigitized at 10 samples per second.

Plot voltage

cremented, and the program begins tolook for the 2nd piece of data. Afterthe 4 digits representing the digitizedvoltage have been stored, the pro-gram checks to see if 256 sampleshave been stored. If they have not,control returns to the beginning of thesubroutine. When all 256 sampleshave been stored, the programreturns to the BASIC routine whichcalled it.

The BASIC routine has the task ofassembling the 4 digits from each con-version into a single number which isequal to the measured voltage. Aflowchart is shown in figure 3. Themachine language assembly routinehas previously taken each of the 4digits from a single conversion andhas stored them in individualmemory locations. The BASICroutine uses the string manipulationcapabilities of Applesoft BASIC tofetch each digit from its memory loca-tion and to assemble all 4 digits into a

single 4-digit voltage. After all 256conversions have been changed intovoltages and stored in a matrix array,the high-resolution graphics routine iscalled and the voltages are plotted asa function of time. It is convenient tohave the voltages stored in a matrixarray so that if further analysis of thedata is required it can be easilyretrieved. Listing 2 shows the codedBASIC program with comments.

To demonstrate the ability of asystem to digitize and display low-frequency signals, a waveformgenerator was connected to theanalog-to-digital converter. Photo 1shows a 0.05 Hz sine wave which wasdigitized at 10 samples per second.Photo 2 shows a 0.05 Hz triangularwave which was digitized at 10samples per second. Photo 3 shows a0.001 Hz sine wave which was digitiz-ed at 1 sample per minute. The resultsare even more impressive when youconsider that this is a data-acquisition

Photo 2: Display of a 0.05 Hz triangularwave digitized at 10 samples per second.

..." ..■■■-.■■■-■■■■ ■ ■

wmE^1^^

Photo 3: Display of a 0.001 Hz sine wavedigitized at 1 sample per minute.

system costing less than $2,000.

At present, a high-speed analog-to-digital converter is being constructedto digitize and analyze the electro-myographic voltages which comefrom muscles. This will allow an in-vestigator to gather data for furtheranalysis of the complex neural-impulse waveform resulting fromstretching a muscle. I anticipate thatonce researchers become aware of thedata acquisition, data analysis, andsystem control that are possible withthese low-cost systems, there will be adrastic increase in their use.H

78 September 1979 © BYTE Publications Inc

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NOTES ONBULLETIN BOARD

The ComputerizedBulletin Board System(CBBS) in the Atlanta GAarea is no longer beingoperated by DC HayesAssociates Inc. The Atlantasystem is now beingoperated by the AtlantaComputer Society. Thetelephone number has beenchanged to (404) 394-4220.A description of a CBBS ap-peared in the article entitled"Hobbyist ComputerizedBulletin Board" by WardChristensen and RandySuess, (November 1978BYTE, page 150).

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Personal Computing-Software (DP 116) Pro-gramming in 6800 and8080 assembly language.For further information,contact Ed Keith, CitrusCollege, 18824 E FoothillBlvd, Azusa CA 91702. ■

80

September 1979 © BYTE Publications Inc Circle 8 on inquiry card.

THE BRAIN is the single topic of theSeptember issue of SCIENTIFIC AMERICAN

Is the brain a computer?What is the role of chemistryin brain function? Is the capa-city of speech "hard-wired"into the brain? Where in thebrain is the mind?

These are questions thatwill engage your interestin the September issue ofSCIENTIFIC AMERICAN.

This issue does not, by anymeans, tell you "how the brainworks." That remains one ofthe most alluring and bafflingquestions on the frontier ofunderstanding. The conver-gence of work in many dis-ciplines—from neurosurgeryto linguistics—has begun toput that question, however, inways that can yield answers.The deep new knowledgeabout the brain, gathered atan accelerating rate in recentyears, shows this organ to bemarvelously designed andcapacitated beyond the wonders withwhich it was invested by ignorantimagination.

Here are the articles:• The Brain (Introduction)The Neuron

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BYTE September 1979 81

Technical Fonum

Operating SystemsLet's Have Some UNIX-Inspired Software

Jim Howell, 5472 Playa Del Rey, San Jose CA 95123

I would like to add to the comments made by JamesJones ("Languages Forum," April 1979 BYTE, page 245)about operating systems.

First, I wholeheartedly agree with his letter. A job con-trol language like OS/370 (or most other large systems,for that matter) would be terrible for personal computeruse. Aside from the pile of job control required to doanything, there are other problems with OS-like systems.The numerous file formats and "access methods" make itdifficult for programs to work together. Specifying filesfor the compiler or assembler to use as work files is anuisance. A file specification (DD statement) also re-quires giving values for several parameters about whichthe user usually doesn't care or shouldn't have to specify.Some of these problems are helped by using procedures(sets of job control that the computer vendor or localsystems programmer has stored on disk for general use),but these may not be what you need, and they also takeup disk space. The space is not significant if your disksstore 100 megabytes, but it could be significant for flop-py disk users.

I would like to strengthen Mr Jones' suggestions thatUNIX be used as a model for a microprocessor operatingsystem. (UNIX is a trademark of Bell Labs.) I have used aUNIX system at work for about a year and it is a verypleasant system to work with. All files on UNIX are aseries of bytes: no structure within files are imposed bythe system. In particular, there is no concept of a "logicalrecord" in UNIX. A "logical record" is the (usually) fixedsize chunk in which files are read or written on bigsystems; often 80 bytes (for card or card-image files), or120 or 132 bytes (for line printers). On UNIX, the end of aline in a text file is indicated by the use of a new-linecharacter. This new-line character (line feed on UNIX)replaces the trailing blanks which are stored on systemsthat use logical records. The new-line character is read orwritten just like any other character. The size of a file isdetermined by how many bytes are written to it; pre-determination of the file size (by guessing?) is notnecessary, or even possible.

Job control language on UNIX is practically non-existent. A command to run a program (such as a com-piler or a user program) consists of the name of the pro-

gram to be executed followed by any parameters that theprogram needs, separated by blanks. (Parameters areoften file names and processing options.) The commandprocessor, which runs as a user program, reads the com-mand line, divides it into "words," and calls the system toexecute the desired program. This system call also passesthe parameters to the executed program. There is no needto describe files in the command since programs need on-ly the name of a file in order to access it. Block sizes andsuch things are not required, even for new files, sincethere is only one format for files.

The following is a summary of the major system callsof UNIX that deal with file or an I/O (input/output)device. A file name in the open and create calls can alsobe a device name (such as the name for a terminal orprinter).

Open (name, mode) opens an existing file (or device)for further operations. "Name" is a pointer to acharacter string which is the name of the file (ordevice) and "mode" indicates reading, writing, orboth.

Create (name, prot) creates a new file, deleting any oldfile whose name is "name." This new file is open-ed for writing. (I would like to see a "mode"argument for this call, in addition to the twospecified. This "mode" would mean the same asit does for "open.")

Read (fildes, buffer, length) reads up to "length" bytesfrom the file whose descriptor is "fildes" into the"buffer". The file descriptor is a small, non-negative integer which was returned by open orcreate. The number of bytes actually read isreturned to the caller. A return of 0 means end offile.

Write (fildes, buffer, length) writes "length bytes to thefile "fildes" from the "buffer."

Seek (fildes, offset, base) moves the read/writepointer of the file "fildes" to a new positionwithin the file. "Offset" is how far to move thepointer, and "base" indicates from the start of thefile, from the current position, or from the end ofthe file.

Close (fildes) closes a file.

Each open file has a read/write pointer associated with

82 September 1979 © BYTE Publications Inc

it. Each read or write call starts reading or writing at thecurrent pointer and advances the pointer by the numberof bytes read or written. By moving the read/writepointer with the "seek" call, random access files (or evenindexed-sequential or other access methods) can beimplemented if required. Note that "read" and "write" arethe lowest levels of I/O calls to the system, and that theyapply to all devices. All device-dependent processing isinside of the operating system. The only thing that a userprogram needs to know about a file after it is opened orcreated is the returned number (file descriptor). There areno "control blocks" or other system-imposed structuresin user programs. (System calls are available in UNIX todetermine the type of device that is associated with anopen file for the few programs that need thisinformation.)

Most current microprocessor operating systems use aspecial character, such as control-z, to mark the end oftext files. These systems take the view that "binary" files(files where all 256 possible bytes are valid) are only forexecutable programs, and in this case reading a few extrabytes from the last sector of the file will not cause anyproblems. Such a scheme prevents the use of binary filesfor other purposes where the exact end of the file must beknown. Possible uses include a work file written by acompiler or assembler and libraries of subroutines in ob-ject format for linking with other programs. (For exampleyou wouldn't want a 20 byte absolute value function toadd 128 bytes to your program, simply because the endof a sector is the best you can do at locating the end of thefunction!) The end of a file should, as in UNIX, be indi-cated by a count of the number of bytes in the file, andthe end of file when reading should be determined bycomparing the read/write pointer of the file to the end-of-file byte count. (Writing past the end of a file causes theend of file pointer to move to the new read/write pointerposition.)

The above is a description of some aspects of UNIX,and is also intended to be used as guidelines in writingany new operating systems for microprocessors (or evenbig systems). One other thing that might be consideredby an operating system writer is the use of a high-levellanguage for most of the operating system and for theprograms that implement supplied commands. Thiswould allow the operating system to be moved to anothermicroprocessor without having to completely rewrite it.

I am about halfway through designing an operatingsystem along the lines of the above suggestions. (I startedbefore Mr Jones' letter appeared in BYTE.) Eventually Iexpect to implement it.

Let me conclude by listing three references which arerecommended to those who are implementing a usablemicroprocessor operating system. The first two were alsomentioned by Mr Jones. ■

REFERENCES

1. Communications of the ACM, July 1974. A revised version of theUNIX article appears in reference 3 below.

2. Software Tools by Kernighan and Plauger.

3. The Bell System Technical Journal, July thru August 1978, part 2.This issue contains about fifteen papers on UNIX. Read especiallythe first 3 or 4 papers, as well as the one called "UNIX on aMicroprocessor" (single-user version on an LIS-11).

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Circle 353 on inquiry card. September 1979 © BYTE Publications Inc 83

Soldering Techniques

William Trimmer

40 James St

Morris Plains NJ 07950

Anyone who can get 3 objects intothe same vicinity can solder. Doing aprofessional job, however, requiressome care and practice. This articledraws on my experience in teaching

electronics and a fine pamphletprepared by NASA entitled "Solder-ing Electrical Connections, A Hand-book" (United States Printing Office,NASA SP-5002). Good soldering

Photo 1: After cleaning the tip of the soldering iron with a wet sponge, prepare it byadding a dab of solder.

Photo 2: Before soldering, the joints should be mechanically fastened.

techniques can save time, com-ponents and frustration.

Good Soldering Techniques

Good soldering starts with a cleansoldering iron tip and well-tinnedparts. Just prior to use, the hot solder-ing iron should be cleaned by wipingit across a wet sponge. The thermalshock and wiping action will cleanthe tip and remove the excess solder.Then touch a bit of solder to the tip(photo 1). The iron is now ready foruse. The parts to be soldered areready when the solder flows quicklyand evenly over their heated surfaces.If this does not happen, clean theparts by brushing, filing, or rubbingwith a pencil eraser. Next flow a thinlayer of solder over the clean surface.The parts are now tinned and readyto be soldered.

The prepared parts should bemechanically fastened together beforemaking the soldering joint (photo 2).The solder should not be expected tosupply mechanical strength. Cleanthe soldering iron tip, and add a dabof solder to the tip. Touch thesoldering iron to the heavier of theparts to be joined, and begin wipingthe solder on the junction between thetwo parts (photo 3).

Do not feed the solder into thesoldering iron tip. When the com-ponents are hot enough, the solderwill begin to melt into the joint. Thesolder should skate over the surfaceslike butter on a hot pan. Now youmust move quickly. Rapidly wipe theentire length of the connection withthe solder, being careful not to applytoo much. The solder should flowsmoothly over the parts. If braidedwire is used, the strands should stillbe visible (photo 4). Doing this welltakes a lot of practice. Now remove

84 September 1979 © BYTE Publications Inc

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BYTE September 1979 85

Photo 3: When soldering, touch the iron to the heaviest part. When the joint is hotenough, the solder will melt on the side opposite the iron.

the iron and hold everything perfectlystill. Any motion while the solder isgoing from the liquid to the solid statewill cause a cold joint. After the jointis cooled, the surface of the soldershould look like a mirror. A goodsolder joint is an accomplishment.

A good way to begin might be todeliberately make some bad solderingjoints. First, shake the two wireswhile the solder is cooling. Notice theundesirable frosted look. Now tryleaving the iron on the joint for morethan several seconds, and you willnotice that a scum forms. Try puttingtoo much solder on the joint. Oftenwhen this blob cools, the frosted sur-face will appear (photo 5). Try to findthe two oldest wires you can. Twistthem together and solder them. Ifthey are covered with an oxide layer,the solder will not transfer from thesoldering iron tip to the wires.Repeated heatings will probablycause the solder to melt around thejoint. Notice how the solder does notflow onto the wires, but sticks toitself. The joint is now probably hotenough to burn the flux.

Inevitably, one has to unsoldersome beautifully soldered joints. Ifthe joint is that of a straight wirethrough a hole, a pull will often ac-complish the task. (Be careful of theflying molten solder.) Often, onemust remove the solder and then un-wrap the wire. The best method usesa fine mesh of properly fluxed copperwire. (An example of this would beSolder-Wick, made by Solder

Photo 4: In a well-soldered braided wire,the strands should still be visible.

Photo 5: Excess solder, poor wetting ofthe wire, frosted surfaces, and blobs ofsolder represent poorly soldered joints.

Removal Co, 1077 E Edna Place,Covina CA 91724. Their 40-4-5 is amedium size, 40-6-2Vi is for largejoints, and 40-2-5 is for very smalljoints.) Push the mesh against thejoint with the soldering iron. Thesolder will be wicked from the jointinto the mesh. Solder suckers are alsoa popular way to remove solder. Thetool is cocked, placed on a heatedjoint, and released. A plunger pullingair through the nozzle of the suckergets most of the solder. This last sug-gestion is the least expensive way.Hold the circuit board and heat thejoint. Rap the edge of the boardsmartly on the work bench. Solderflies in every direction, but the joint isclean.

Good soldering takes patience andpractice. Fortunately, if properlydone, the soldering joints are almostnever the culprits when a circuit doesnot work. The following are somesuggestions that will make solderingeasier.

Tools

The soldering iron should be welltinned (covered with solder), andshould quickly raise the joint to theworking temperature. I prefer a 30 or40 W element for a pencil solderingiron. Cleaning the tip with a wetsponge before soldering will bring thetip down to the correct temperaturerange (about 700°F). This slightlygreater wattage will allow largerpieces to be soldered. Better yet arethe temperature controlled pencilsoldering irons. Soldering guns aretoo large and hot for all but the mostmassive soldering joints. If you buy anew soldering iron, wrap the tip withsolder before turning it on. This willcoat the tip with solder before it getshot enough to oxidize. Place the ironin a protective cage towards the backof your work bench so that it can notburn anything. If the iron is not goingto be used for a while, unplug it.

It is very tempting to buy less ex-pensive solder. Don't do it. Soldercosts very little compared to othercomponents. The best solder is Eutec-tic, which is 63% tin and 37% lead.This mixture passes directly from aliquid to a solid stage without goingthrough a plastic region. As a result,good soldering joints are easier tomake. Solder composition is gener-ally given by two numbers, such as40-60. The first number is the amountof tin, the second is the amount of

86

September 1979 © BYTE Publications Inc

lead. The above solder is less expen-sive to make than Eutectic solderbecause tin is the expensive element.However, this solder has a plasticregion of about 180°F. The joint mustbe held completely motionless whilethe solder is cooling through thisplastic stage. Always use a rosin fluxwhen soldering. Never let your irontouch acid flux. An 18 or 20 gaugesolder with a rosin core works nicely.There are a number of other usefultools. These include long nose pliers,diagonal cutting pliers, wire strip-pers, a slotted screwdriver, a dentalpick, and plastic electrical tape.

Assembly Before Soldering

A convenient substrate upon whichto build electronics is predrilledepoxy board. The holes should be on0.1 inch centers in a square grid fordigital work. Typical hole sizes are0.042 or 0.062 inches. Vector-typeterminals (Vector Electronic Co Inc,12460 Gladstone Ave, Sylmar CA91342) can be pushed into the holesand the discrete components solderedto the terminals. The majority ofdigital electronics come in the dual-in-line packages. A convenient wayto mount dual-in-line packages iswith circuit-stick-type subelements(Circuit-Stik Inc, 24015 Gardnier St,POB 3396, Torrance CA 90510).These are very thin sheets of glassepoxy with preetched copper lands onone side and glue on the other. Theholes on the subelements are alignedwith the holes on the predrilled circuitboard, and carefully pressedtogether. The dual-in-line packagesand components can then be pushedthrough from the other side of theboard, and soldered to the preetchedcopper lands. One can then wire thecorrect lands together. Because thespacing between the pins of the dual-in-line packages is only 0.1 inches,hand soldering requires care. Whenworking with dual-in-line packages, Iprefer to solder sockets onto theboard, and plug the dual-in-linepackages into the sockets. Thismethod makes troubleshootingeasier.

It is important to be neat whensoldering. Try to lay the board outlogically. Do not crowd the com-ponents together. If it is your owndesign, you will probably want toadd something after the board ismade. Place all of the resistors thesame way so that their color codes

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(Level "A" makes a perfect OEM controller for indsutrialapplications and is available in a special Hex Version which canbe programmed using (he Netronics Hex Keypad/Display.)

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Monitor ROM (ASCII Keyboard Version): 2k bytes ofdeluxe system monitor ROM located at F000 leaving 0000 freefor user RAM/ROM. Features include tape load with labeling(so that Explorer/85 can locate your specific program auto-matically). . .tape dump with labeling.. .examine/changecontents of memory.. .insert data (such as from a paper tapereader).. .warm start (a feature which is especially helpful indebugging routines as it allows you to save the contents of theregisters which might otherwise be lost along with the rest ofyour program when a bug causes it to self-destruct. The warmstart feature helps you pinpoint the exact line in your programthat contains an error). . .examine and change allregisters... single step with register display at each break point,a debugging/training feature ..go to execution address...move blocks of memory from one location to another.. .fillblocks of memory with a constant... display blocks of memory.. .automatic baud rate selection... variable display line lengthcontrol (1-255 characters/line).. .channelized I/O monitorroutine with 8-bit parallel output for high speed printer...

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□ Level "B" (S-100) Kit, $49.95 plus$2 p&h.

D Level "C" (S-100 6-eard expander)Kit, $39.95 plus $2 p&h.

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serial console in and console out channel so that monitor cancommunicate with I/O ports.

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Level "B" Specifications

Level"B" provides the S-100 signals plus buffers/drivers tosupport up to six S-100 bus boards and includes: addressdecoding for onboard 4k RAM expansion selectable in 4kblocks.. .address decoding for onboard 8k EPROM expansionselectable in 8k blocks.. .address and data bus drivers foronboard expansion... wait state generator (jumper selectable),to allow the use of slower memories.. .two separate 5 voltregulators to insure maximum stability and a noise free bus.Level "C" Specifications

Level "C" expands Explorer's motherboard with a card cage,allowing you to plug up to six S-100 cards directly into themotherboard. Both cage and cards are neatly contained insideExplorer's deluxe steel cabinet. Level "C" includes a sheetmetal superstructure, a 5-card gold plated S-100 extension PCboard which plugs into the motherboard, 12 card guides, andall brackets and hardware needed for complete assembly. Justadd required number of S-100 connectors

In addition to six S-100 cards, Level "C" will also supportan optional test socket that allows you to perform tests andmaintenance on both sides of any individual S-100 card, underactual operating conditions. (You won't need Level "C" unlessyou are planning to use 3 or more S-100 cards with yourExplorer/85.)

Level "D" Specifications

Level "D" provides 4k or RAM, power supply regulation,filtering decoupling components and sockets to expand yourExplorer/85 memory to 4k (plus the original 256 bytes locatedin the 8155A).

The 2114 static RAM is organized as 1024 words by 4-bitsusing N-channel Silicon-Gate MOS technology and can belocated anywhere from 0000 to EFFF in 4k blocks.Level "E" Specifications

Level "E" adds sockets for 8k of EPROM to use the popularIntel 2716 or theTl 2516. It includes all sockets, power supplyregulator, heat sink, filtering and decoupling components.Sockets may also be used for soon to be available RAM IC's(allowing for up to 12k of onboard RAM).Order A CoordinatedExplorer/65 Applications Pak!

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sonalized disk operating system—just mplug it in and you're up and running!), I$699.95 plus $5 p&h.

□ Power Supply for North Star Disk IDrive, $39.95 plus $2 p&h.D Deluxe Case for North Star Disk IDrive, $39.95 plus $2 p&h.D Experimenter's Pak (see above), I$199.90 postpaid.

D Student Pak (see above), $319.851postpaid.

G Engineering Pak (see above), |$514.75 postpaid. ■

□ Business Pak (see above), $1599.401postpaid.

D Deluxe Steel Cabinet for ASCIIKeyboard/Terminal, $19.95 plus $2.50p&h.

□ Power Supply Kit (± 8V @ 5 amps)in deluxe steel cabinet, $39.95 plus $2p&h.

D Cold Plated S-100 Bus Connectors,$4.85 each, postpaid.

□ RF Modulator Kit (allows you touse your TV set as a monitor), $8.95postpaid.

□ 16k RAM Kit (S-100 Board expandsto 64k), $199.95 plus $2 p&h.

□ 32k RAM Kit, $329.95 plus $2 p&h.D 48K RAM Kit, $459.95 plus $2 p&h.D 64k RAM Kit, $589.95 plus $2 p&h.D 16k RAM Expansion Kit (to expandany of the above up to 64k), $139.95plus $2 p&h each.

D Intel 8085 cpu User's Manual, $7.50postpaid.

D Special Computer Grade CassetteTapes, $1.90 each or 3 for $5, postpaid.D 12" Video Monitor (10 MHz band-width), $139.95 plus $5 p&h.D North Star Double Density FloppyDisk System (One Drive) for Explorer/85 (includes 3 drive S-100 controller,DOS, and extended BASIC with per-

Total Enclosed $ 1

(Conn. res. add sales tax) By—

D Personal Check D M.O./Cashier's I

Check □ Visa □ Master Charge |

(Bank #_

Signature.PrintName

_£xp. Date _

City.

_Zip„

D Send Me Information

Circle 280 on inquiry card.

September 1979 © BYTE Publications Inc 87

Circle 141 on inquiry card.

16K Static RAMBoards for the <SS-50 Bus ^

• Gold bus connectors

• 4 separate 4K Blocks

• Individual Addressing,Write Protect, and Enable/Disable for each block Memories...

s29813

As above with

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control

features.

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SS 50 BUS 80 x 24VIDEO BOARD

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The user can choose and intermix 384 differentcharacters from any or all of the character generatorsand display up to 256 at one time, normally or inversely,and at full or half intensity, at any location on thescreen. Contiguous 8x10 character cells permit solidlines and connecting patterns with user definablegraphic elements.

It is addressable to any 2K boundary. GHOSTable ad-dressing allows multiple boards at the same address,making it ideal for multi-user applications. The availablesoftware includes a GMXBUG video based 3K ROMmonitor, stand alone driver routines, and a program tocreate user defined characters.

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AWG

Diameter (mm)

Ohms per 1000m

Current Capacity (Amperes)

10

2.6

3.3

26

12

2.0

5.2

16

14

1.6

8.3

10

16

1.3

13

6

18

1.0

21

4

20

0.81

33

2.5

22

0.64

53

1.6

24

0.51

84

1.0

26

0.40

135

0.6

28

0.32

214

0.4

30

0.25

341

0.2

Table 1: Approximate values for various American Wire Gauge (AWG) sizes of copperwire.

can be read from the same side of theboard. Run the wires in an orderlymanner. I prefer to mount com-ponents like resistors, transistors, etc,slightly off the board. This improvesthe heat transfer, and makes it easierto slip in a probe for testing. Com-ponents that weigh 0.5 ounces ormore should be mechanicallymounted to the board. A little epoxyor silicon rubber works wonders formounting these components.

Properly stripping wire is adichotomy. First, the insulationshould be cut and removed. Second,the wire should not be cut. (If strand-ed wire is used, a nick will cause onlya few strands to break.) With prac-tice, you can strip the insulationwithout cutting the wire. Try cuttingslowly through a wire. Notice the dif-ference in the feel between the insula-tion and wire. Now cut off the wireand start again with a clean end. Cutdown until the wire is felt, then relaxthe stripper slightly. Now rotate thewire 45° and again squeeze a bit. Thiswill cut the insulation all the wayaround, not just where the stripperteeth cut the deepest. Be sure to openthe stripper slightly and pull the in-sulation off the wire. With practice,you can learn not to nick the wire.The secret is to stop cutting justbefore the cutter reaches the wire. Afirm pull will usually break off the re-maining insulation. If you still nickthe wire, take heart, you have muchcompany.

Table 1 gives the American WireGauge (AWG) size, the approximatediameter, ohms per 1000 meters, andcurrent carrying capability of copper

wire. Try to use a number of wires ofdifferent colors and gauges. This notonly matches the current capabilitywith the load, but also makes it easierto trace wires.

Finally, some words on safety: besure that you have a stand for youriron; always wear shoes and safetyglasses; and try not to flick solder onanything important. When cuttingwires, hold the cutter so that thepieces fly away from you. To avoidpotentially lethal shocks, it is best tohave a rubber mat beneath your feetand stool.

By following these rules and tech-niques, almost anyone can learn tosolder well.H

"WE WILL RETURN TO OUK PROS^M « JU57" -1 MOMENT, BUT'FlRST ft MESSAGE ffX». OUR SPONSOR, '

88

September 1979 © BYTE Publications Inc

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power-one

D.C. POWER SUPPLIES

Power One Drive • Camarillo, CA 93010 • (805) 484-2806 • TWX 910-336-1297

Circle 309 on inquiry card.

BYTE September 1979 89

Software /

with / ManualManual/ Alone

DIGITAL RESEARCH

D CP/M* Floppy Diskette Operating System —

Packages supplied on diskette complete with 8080 as-sembler, text editor, 8080 debugger and various utilitiesplus full documentation. CP/M available configured formost popular computer/disk systems including: NorthStar Single, Double or Quad density, Altar 8" disks,Helios II, Exidy Sorcerer, Vector MZ, PolyMorphic8813t* Heath H17t or H89f, TRS-80t, iCOM 3712 andiCOM Micro Disk plus many other configurations avail-able off the shelf $145/525

□ MAC — 8080 Macro Assembler. Full Intel macro defini-tions. Pseudo Ops include RPC, IRP, REPT, TITLE,PAGE, and MACLIB. Z-80 library included. ProducesIntel absolute hex output plus symbols file for use by SID(see below) $100/S15

□ SID — 8080 symbolic debugger. Full trace, pass countand break-point program testing system with back-traceand histogram utilities. When used with MAC, providesfull symbolic display of memory labels and equatedvalues $85/$15

□ TEX — Text formatter to create paginated, page-numbered and justified copy from source text tiles, di-rectable to disk or printer $85/$ 15

Q DESPOOL — Program to permit simultaneous printingof data from disk while user executes another programfrom the console $50/$10

(M-M^f^L.

OM

□

□

□

□

□

□

MICROSOFT

Disk Extended BASIC — Version 5, ANSI compati-ble with long variable names, WHILE/WEND, chaining,variable length (He records S300/S25

BASIC Compiler — Language compatible with Ver-sion 5 Microsoft interpreter and 3-10 times faster execu-tion. Produces standard Microsoft relocatable binary out-put. Includes Macro-80. Also linkable to FORTRAN-80 orCOBOL-80 code modules S350/S25

FORTRAN-80 — ANSI '66 (except for COMPLEX)plus many extensions. Includes relocatable object com-piler, linking loader, library with manager. Also includesMACRO-80 (see below) S400/S25

COBOL-80 — ANSI 74 Relocatable object output.Format same as FORTRAN-80 and MACRO-80modules. Complete ISAM, interactive ACCEPT/DIS-PLAY, COPY, EXTEND S625/S25

MACRO-80 — 8080/Z80 Macro Assembler. Intel andZilog mnemonics supported. Relocatable linkable output.Loader, Library Manager and Cross Reference Listutilities included $149/$15

EDIT-80 — Very fast random access text editor for textwith or without line numbers. Global and intra-line com-mands supported. File compare utility included S89/S15

Software /

with /ManualManual/ Alone

XITAN (software requires ZBO" CPU)

□ Z-TEL — Text editing language. Expression evaluationiteration and conditional branching ability. Registersavailable for text and commands. Macro commandstrings can be saved on disk for re-use $69/$20

□ ASM Macro Assembler — Mnemonics per Intel withZ-80 extensions. Macro capabilities with absolute Intelhex or relocatable linkable output modules. New version3 with added features S69/$20

D LINKER — Link-edits and loads ASM modules S69/S20

□ Z-BUG debugger — Trace, break-point tester. Supportsdecimal, octal and hex modes. Disassembler to ASMmnemonic set. Emulation technique permits full tracingand break-point support through ROM S89/S20

□ TOP Text Output Processor — Creates page-numbered,justified documents from source text files ... $69/$20

□ A4 package includes z-tel, asm, linker, z-bug,

TOP $299/$40

EIDOS SYSTEMS

□ KISS — Keyed Index Sequential Search. Offers com-plete Multi-Keyed Index Sequential and Direct Access filemanagement. Includes built-in utility functions for 16 or32 bit arithmetic, string/integer conversion and stringcompare. Delivered as a relocatable linkable module inMicrosoft format for use with FORTRAN-80 or COBOL-80, etc SS3S/$23

□ KBASIC — Microsoft Disk Extended BASIC with allKISS facilities, integrated by implementation of nineadditional commands in language. Package includesKISS.REL as described above, and a sample mail listprogram S995/S45

MICROPRO C^^

D Super-Sort I — Sort, merge, extract utility as absoluteexecutable program or linkable module in Microsoft for-mat. Sorts fixed or variable records with data in binary,BCD, Packed Decimal, EBCDIC, ASCII, floating, fixedpoint, exponential, field justified, etc. etc. Even variablenumber of fields per record! $225/$25

□ Super-Sort II-

only

□ Super-Sort III — As II without SELECT/EXCLUDE

$125/$25

D Word-Star — Menu driven visual word processing sys-tem for use with standard terminals. Text formatting per-formed on screen. Facilities for text paginate, pagenumber, justify, center, underscore and PRINT. Editfacilities include global search and replace, read/write toother text files, block move, etc. Requires CRT terminalwith addressable cursor positioning $445/$25

'/

Above available as absolute Drooram $175/$25

Software /

with /ManualManual/ Alone

D Word-Master Text Editor — In one mode has super-set of CP/M's ED commands including global searchingand replacing, forward and backwards in file. In videomode, provides full screen editor for users with serialaddressable-cursor terminal $125 $25

SOFTWARE SYSTEMS

□ CBASIC-2 Disk Extended BASIC — Non-interactiveBASIC with pseudo-code compiler and runtime interpre-ter. Supports full file control, chaining, integer and ex-tended precision variables, etc $90/$15

"CP/M is a trade name of Digital Research* Z80 is a trademark of Zilog, Inc."WHATSIT? is a trademark of ComputerHead ware.

tCP/M for Heath, TRS-80 Model I and PolyMorphic 8813 aremodified and must use especially compiled versions of systemand applications software,tfPolyMorphic 8813 CP/M scheduled for September 15 release.

STRUCTURED SYSTEMS GROUP

D General Ledger — Interactive and flexible systemproviding proof and report outputs. Customization of COAcreated interactively. Multiple branch accounting centers.Extensive checking performed at data entry for proof,COA correctness, etc. Journal entries may be batchedprior to posting. Closing procedure automatically backsup input files. All reports can be tailored as necessary.Requires CBASIC $899/$25

□ Accounts Receivable — Open item system withoutput tor internal aged reports and customer-orientedstatement and billing purposes. On-Line Enquiry permitsinformation tor Customer Service and Credit depart-ments. Interface to General Ledger provided if both sys-tems used. Requires CBASIC $699/$25

D Accounts Payable — Provides aged statements ofaccounts by vendor with check writing for selected in-voices. Can be used alone or with General Ledger and/orwith NAD. Requires CBASIC $699/$25

□ NAD Name and Address selection system — interactivemail list creation and maintenance program with outputas lull reports with reference data or restricted informa-tion for mail labels. Transfer system for extraction andtransfer of selected records to create new files. RequiresCBASIC $79/$20

D QSORT — Fast sort/merge program for files with fixedrecord length, variable field length information. Up to fiveascending or descending keys. Full back-up of input filescreated S95/S20

tRAHAM-DORIAN SOFTWAREYSTEMS

D PAYROLL SYSTEM — Maintains employee masterfile. Computes payroll withholding for FICA, Federal andState taxes. Prints payroll register, checks, quarterly re-ports and W-2 forms. Can generate ad hoc reports andemployee form letters with mail labels. RequiresCBASIC. Supplied in source code $590/$35

□ APARTMENT MANAGEMENT SYSTEM - Fi-nancial management system for receipts and securitydeposits of apartment projects. Captures data on vacan-cies, revenues, etc. for annual trend analysis. Daily reportshows late rents, vacancy notices, vacancies, incomelost through vacancies, etc. Requires CBASIC. Suppliedin source code $590 $35

Software for most popular 8080IZ80 computer disk systemsincluding NORTH STAR, MICROPOUS, iCOM, DYNABYTE DB8I2,SD SYSTEMS, ALTAIR, EXIDY SORCERER, VECTOR MZ,8"IBM, HEATH H17 & H89, HELIOS, IMSAI VDP42 & 44, REX,POLYMORPHIC 8813' and OHIO SCIENTIFIC formats.

90 BYTE September 1979

Software j

with /ManualManual/ Alone

□ INVENTORY SYSTEM - Captures stock levels,costs, sources, sales, ages, turnover, markup, etc.Transaction information may be entered for reporting bysalesman, type of sale, date of sale, etc. Reports avail-able both for accounting and decision making. RequiresCBASIC. Supplied in source code $590/535.

D CASH REGISTER — Maintains files on daily sales.Files data by sales person and item. Tracks sales, over-rings, refunds, payouts and total net deposits. RequiresCBASIC. Supplied in source code 5590/535

MICRO FOCUS

□ CIS COBOL — Version 3 is ANSI 74 subset with ex-tensions which offer powerful interactive screen format-ting and built in cursor control. Version 4 additionally oi-lers full level 1 ANSI for Nucleus, Table Handling, Se-quential Relative and Indexed I/O, Inter-Program Com-munication and Library

Version 3, 5650/550

Version 4, S850/S50

□ FORMS — Interactive utility to create CIS COBOLsource code to perform CRT screen handling in applica-tion programs. Supports full prompt text, protected fieldsand input validation against data type and range

expected $150/$15

When purchased with CIS COBOL $125/515

OTHER

D tiny C — Interactive interpretive system for teachingstructured programming techniques. Manual includes fullsource listings $75/540

D C Compiler — Supports most major leatures of lan-guage, including Structures, Arrays, Pointers, recursivefunction evaluation, linkable with library to 8080 binaryoutput. Lacks data initialization, long & float type and sta-tic & register class specifiers. Documentation includes"C" Programming Language book by Kernighan &Ritchie $110/515

□ ALGOL 60 Compiler — Powerful block-structuredlanguage featuring economical run time dynamic alloca-tion of memory. Very compact (24K total RAM) systemimplementing almost all Algol 60 report features plusmany powerful extensions including string handling directdisk address I/O etc. Requires Z80 CPU ... .$199/520

□ Z80 Development Package — Consists of: (1) diskfile line editor, with global inter and intra-line facilities; (2)Z80 relocating assembler, Zilog/Mostek mnemonics,conditional assembly and cross reference tablecapabilities; (3) linking loader producing absolute Intelhex disk tile $95/$20

□ Z80 Debugger — Trace, break and examine registerswith standard Zilog/Mostek mnemonic disassembly dis-plays. Facilities similar to DDT. $35 when ordered withZ80 Development Package $50/$10

D DISTEL — Disk based disassembler to Intel 8080 orTDL/Xitan Z80 source code, listing and cross referencefiles. Intel or TDL/Xitan pseudo ops optional. Runs on8080 $65/$10

□ DISILOG - A DISINTEL to Zilog/Mostek mnemonicfiles. Runs on Z80 only $65/510

□ TEXTWRITER II — Text formatter to justify and pagi-nate letters and other documents. Special features in-clude insertion of text during execution from other diskfiles or console, permitting recipe documents to becreated Irom linked fragments on other files. Ideal forcontracts, manuals, etc. Also creates form letters in con-junction with a mail list file $75/510

□ TEXTWRITER III — All the features of TW II plus gen-eration of table of contents, sorted index and handling offootnotes. TW II users may upgrade for $60. $125/$10

□ WHATSIT?*** — Interactive data-base system usingassociative tags to retrieve information by subject. Hash-ing and random access used for fast response. RequiresCBASIC $125/525

□ XYBASIC Interactive Process Control BASIC — Fulldisk BASIC leatures plus unique commands to handlebytes, rotate and shift, and to test and set bits. Availablein Integer, Extended and ROMable versions.

Integer Disk or Integer ROMable $295/525

Extended Disk or Extended ROMable 5395/525

Lifeboat Associates

2248 Broadway, N.Y., N.Y. 10024(212)580-0082 Telex; 668-585

Software

□ manual alone

□ manual alone

□ manual alone

□ Check DU.P.S. COD □ Visa □ Master Charge

Exp. Date

Shipping

$1.00 for C.O.D.

Total

Account #

Signature

My computer configuration (specifying disk system):

Name

Address (No P.O. Box)

City

State

Zip

Price

Orders must specifydisk systems andformats: e.g. NorthStar single or doubledensity, IBM single or2D/256, Altair, HeliosII, Micropolis Mod I orII, 614* soft sector(Micro iCOM/SDSystems Dynabyte), etc.

Add $1/item shipping($2 min.). Add $1additional for UPSC.O.D.

Manual costapplicable againstprice ol subsequentsoftware purchase.

The sale of eachpropriety softwarepackage conveys alicense lor use on onesystem only.

Software /

with /ManualManual/ Alone

D SMAL/80 Structured Macro Assembled Language —Package of powerful general purpose text macro proc-essor and SMAL structured language compiler. SMAL isan assembler language with IF-THEN-ELSE, LOOP-REPEAT-WHILE, DO-END, BEGIN-END constructs 575/51 5

D Selector II — Data Base Processor to create and main-tain single Key data bases. Prints formatted, sorted re-ports with numerical summaries. Available for Microsoftand CBASIC (state which). Supplied in source code 5195/520

□ Selector III — Mufti (i.e., up to 24) Key version of Selec-tor II. Comes with applications programs including SalesActivity, Inventory, Payables, Receivables, Check Regis-ter, Expenses. Appointments, and Client/Patient. Re-quires CBASIC.Supplied in source code $295/520

Enhanced version for CBASIC-2 $345/520

□ CPM/374X Utility Package — Has full range offunctions to create or re-name an IBM 3741 volume, dis-play directory information and edit the data set contents.Provides full file transfer facilities between 3741 volumedata sets and CP/M files $195/510

D Flippy Disk Kit — Template and instructions to modifysingle sided 5V4" diskettes for use of second side in sin-gled sided drives $12.50

□ BASIC Comparison — A comprehensive featuresand performance analysis of five 8080 disk BASIC lan-guages — CBASIC, BASIC-E, XYBASIC, Microsoft DiskExtended BASIC, and Xitan's Disk BASIC. Itemizes re-sults of 21 different benchmark tests for speed and accu-racy and lists instructions and features of each BASIC (send 20? S.A.S.E.) FREE

Lifeboat Associates

2248 BroadwayNew York, N.Y. 10024

"The Software Supermarket is a trademark ol Lifeboat Associates

BYTE September 1979

91

Blubs and Newsletters

Washington DCComputer Club

The Washington AmateurComputer Society (WACS)is an organization dedicatedto personal computing.They are organized to pro-vide a forum for the com-puter hobbyist and studentof computing science. TheSociety meets on the lastFriday of each month in the1st floor lecture hall inKeane Hall on the campusof the Catholic University ofAmerica. The meetings startat 7:30 PM

JWAC, the club's news-letter, is published for Socie-ty members and exchangewith other hobby organi-zations. The newsletter isprimarily an electronicsjournal. Annual dues havebeen set at $3.50 per year to

cover the cost of 1st classpostage for the journal andto defray the expenses ofexchanging correspondencewith other personal com-puting organizations. Non-members may subscribe tothe journal at the rate of $5per year. WACS is inter-ested in exchanging news-letters with other organiza-tions to further the inter-change of hobbyist infor-mation. Contact WashingtonAmateur Computer Society,c/o 4201 MassachusettsAve, #168, Washington DC20016.

Cromemco UserSystems andSoftware Pool

Cromemco User, Systemsand Software Pool is an

HARD DISCFOR S100 MICROS

The XCOMP DCF-10 Disc Controller pro-vides the OEM with a high performance,low.cost interfaceforfixed and removable(2315 or 5440) cartridge disc drives. TheDCF-10 is currently supported by twooperating systems. For information ormanuals, contact XCOMP.

XCOMP

INCORPORATED

9915-A Businesspark Ave., San Diego, CA 92131 • (714) 271-8730

independent group for usersof Cromemco computers.Board owners are alsowelcome. The purpose ofCUssP is the exchangeamong users of Cromemcohardware and software ofoperating notes, bugs andtheir fixes, evaluation ofhardware and software, userwritten software, and otherannouncements relating toCromemco and associatedproducts.

The 1st volume of 3newsletters included articleson changes in 16 K byteBASIC, CDOS I/O (input/-output) drivers, disk sectorsand clusters, hardwaremodifications, etc. Thisvolume is available for $10in the US, Canada, andMexico; and $12 in USfunds for airmail deliveryoutside these regions.Membership with the 2ndvolume is the same price asthe 1st. There is also aspecial rate of 3 volumes (9issues) for $25 in the US,Canada, and Mexico and$30 elsewhere.

Contact Cromemco User,Systems and Software Pool,POB 784, Palo Alto CA94302.

Computer Graphics

Letter Published

by Harvard

Readers of the new Har-vard Newsletter on Com-puter Graphics will be ableto keep abreast of computergraphics in all its myriadramifications. The newslettermonitors important commer-cial, technological, and pro-duct developments, as wellas market, application, andlearning opportunities.Among the regular depart-ments are News and Trends,Products, Markets, Applica-tions, R and D, Conferencesand Seminars, Companies,Business and Financial, andState-of-the-Art Technology.The newsletter will be

published twice a month.

The content will encom-pass management and statis-tical graphics, computergraphic-aided design,engineering and manufac-turing, image processing,and automated cartography,plus other related areas.Trends in these areas,whether applied to big orsmall computers, stand-alone terminals, timesharingnetworks, users, vendors,will be followed. Readerswill also learn where to ob-tain further information onthe material covered.

The subscription fee for 1year is $125; a 9-issue trialsubscription is available for$45. Airmail outside ofNorth America is $19.50 for1 year or $9.75 for the trial.Contact William Nisen, Har-vard University, Laboratoryfor Computer Graphics, 520Gund Hall, Cambridge MA02138.

Akron OhioDigital Group

The Akron Digital Groupmeets on the 4th Wednesdayof each month at 7 PM atthe Kenmore Public Library,2200 14th St SW, AkronOH. The club programs areaimed toward the smallsystems hobbyist with tipson programming and hard-ware application. Micro-processor classes areplanned for the fall. ContactLou Laurich, Akron DigitalGroup, 107 7th St NW,Barberton OH 44203.

TRS-80 Publication

Insiders: The TRS-80Hardware Journal withMachine Software is apublication for any TRS-80owner or user interested inmore than BASIC. Bothbeginners and experts willfind articles on machine

92 September 1979 © BYTE Publications lnc Circle 393 on inquiry card.

language programming,hardware modifications, andother computer languages.Published since June of1978, articles have describedthe differences in Level IIread-only memories, how toget sound effects and musicwithout a hardwaremodification, new languagesfor the TRS-80, and manyother subjects. Regularfeatures include a columnwhich reviews variousprinters, the Disc File whichcovers the latest in DOS andcompatible drives, a DearAunt TRiSh question andanswer column, and learningmachine language with LevelII.

A new section of the jour-nal will cover several of thenew languages for theTRS-80. Future issues willinclude regular features onFORTRAN, FORTH, andother languages. Also, therewill be regular articles onCP/M, reviews of variouscommercially available pro-grams, and more on bothLevel II and DOS.

Subscriptions are availablefor 6 issues through Com-puter Cablevision, 261742nd St NW, Suite 2N,Washington DC 20007.

New PET Users Group

Forming in Washington

and Oregon

Individuals interested informing a PET Users Groupin the Oregon andWashington area shouldcontact NW PET UsersGroup, c/o John F Jones,2134 NE 45th Ave, PortlandOR 97213.

COSMAC Users GroupActive Again

After several unavoidabledelays, the COSMAC UsersGroup is back in full opera-tion and The 1802Peripheral newsletter isbeing published on a mon-thly basis. Informationabout the group may beobtained by writing to

Patrick Kelly, Director,COSMAC Users Group,POB 7162, Los Angeles CA90022. Please include astamp with your inquiry.

New Speechlab UsersGroup Formed

Heuristics Inc, manufac-turer of Speechlab (a speechrecognition unit for theApple and all S-100 buscomputers), has announcedthe formation of a usersgroup. The users grouprequests that all interestedSpeechlab users send theirunique uses of the hardwareor software to Tom Larson,Director of Sales, HeuristicsInc, 900 N San Antonio Rd,Los Altos CA 94022. Adirectory of users and appli-cations will be published ata later date.

Aim-65 Newsletter

The Target is a bi-monthly newsletter forowners or prospectiveowners of Aim 65 systems.The subscription rate is $5for 1 year. Contact Custom-Tronics, POB 4310, Flint MI48504.

Solano TRS-80Users Club

The Solano TRS-80 UsersClub is an informal groupthat gets together to discussmutual problems and exper-iences. Their meetings areheld every 3rd Thursdaystarting July 5th at Owens-Illinois, 2500 HuntingtonDr, Fairfield CA. ContactDave or Steve Irwin, 550Marigold Dr, Fairfield CA94533, or call (707)422-3347.

The TulsaComputer Society

The Tulsa ComputerSociety meets the last Tues-day of every month at 7:30

PM. The meeting place isthe Tulsa Vocational-Technical School seminarroom at 3420 SouthMemorial Dr (behindEdison's Department Store).Membership in TCS is $6annually and includes a 1year subscription to theclub's newsletter, The I/OPort. Contact The TulsaComputer Society, POB1133, Tulsa OK 74101.

Wichita Valley

TRS-80 Users Group

Sustains Computer

Loss in

Recent Tornado

In the recent tornadowhich wreaked unholyhavoc on our city, many ofus in the Wichita ValleyTRS-80 Users Group lostour computers, our tape anddisk library of software, andour library of computerbooks and periodicals. Evenour club's library of soft-

ware and publications wasdestroyed.

We all have plans toreplace our personal com-puters and software, but atthis time I am particularlyinterested in trying to helpour club replace its loss.

Any club, publisher, soft-ware producer, or individualwho wishes to do so, maycontribute noncash items,such as software, back issuesof computer publications,and books on computers.

Our address is the WichitaValley TRS-80 Users Group,POB 4391, Wichita FallsTX 76308.

Thank-you, our club willbe grateful.

J Wesley B TaylorClub Secretary

Although this letter cer-tainly speaks for itself, it isour sincere hope that you oryour group will seriouslyconsider contributing non-cash computer related itemsto this needy organization.*

computer mart of new jerseycomputer mort of Pennsylvania

the

microcomputer

people®

Computers don't moke acomputer store, PEOPLE do. Ourpeople hove been involved withmicrocomputers since day one.We offer experience andexpertise unparalleled in themicrocomputer industry. Whetheryou are in the market for ocomplete system, peripherals,custom software, service, or justsome friendly advice; there simplyis no other place to go.

Computer Mart of Now Jonoy

501 Rout* 27iMlln. NJ 08800(201) 280-0600

STOKE HOURSTum. - Sat. 10am - 6pTuai. 0 Thun. 'till 9pCLOSED MONDAYS

Computar Mart of P»nnjy Ivor

330 DoKalb Pill*

King of Prussia, PA 19406

(213) 263-2380

Circle 66 on inquiry card.

September 1979 © BYTE Publications Inc

93

^MINIMAX

C0MPU

"FULLY INTEGRATED COMPUTER SYSTEM"

MINIMAX SERIES COMPUTER

THE MINIMAX SERIES WAS DESIGNED

TO OFFER THE MARKET MINICOMPUTER

CAPABILITIES AT MICROCOMPUTER PRICES.

COMPARE THE CAPABILITIES & PRICE!

CONTACT NEECO FOR FULL SPECS - FREE MINIMAX MANUAL.

MEET THEMINIMAX COMPUTER THE MINIMAX SERIES computer was designed by industry professionals.

frfffV KsKJ COMPARE THE PRICE AND FEATURES TO ANY OTHER COMPUTER IN ITS CLASSI

MINIMAX I - .8 MEGABYTEON LINE MINIFLOPPY STORAGEMINIMAX II - 2.4 MEGABYTEON LINE 8" FLOPPY STORAGE

MINIMAX I -MINIMAX II -

$4495$5995

•THE MINI MAX SERIES COMPUTER IS AN INTEGRATED. COMPACT UNIT CONTAINING THE CPU. DUAL DENSITY DISK STORAGE. 12INCH CRT, AND FULL STYLE KEYBOARD, WITH SEPARATE NUMERIC ENTRY PAD. ALL KEYS (INCLUDING CURSOR) WITH FULLREPEAT • HYBRID 2 MEGAHERTZ 6502 CPU • 108K SYSTEM RAM (48K USER) • FASTEST FLOPPY DISK ACCESS (24K LOADS IN 4.2SECONDS) • 16K ROM CONTAINS COMPUTHINK BASIC (AN EXTENDED MICROSOFT BASIC) WITH EXTENDED PRECISION, DOSINCLUDES COMPLETE FILE I/O WITH FULL RANDOM ACCESS, COMPLETE MONITOR WITH DEBUG & TRACE, AND TINY 6502ASSEMBLER • COMPLETE HIGH RESOLUTION GRAPHICS WITH INDIVIDUAL DOT (240x512) POINT SCREEN ADDRESSABILITY •FULL SCREEN TEXT EDITING WITH OVERWRITE. INSERTION OR DELETION • SPLIT SCREEN/WINDOW MODES • INDIVIDUALFIELD EDITING WITH FIELD PROTECT AND AUTO SKIP TO NEXT FIELD • DISK STORAGE SYSTEM TRANSFERS 6K PER SECONDWITH AUTO VERIFY AND PARITY CHECK • 12 INCH CRT-64 CHARACTERS BY 30 LINES. UP TO THREE PROGRAMMABLECHARACTER FONTS FOR LANGUAGES OR SPECIAL CHARACTERS • • • SWITCHABLE 110 OR 220V OPERATION • • • • HYBRIDCPU IS MICROPROGRAMMABLE WITH 64 USER DEFINABLE OPCODES. CHOICE OF 800K OR 2.4 MEGABYTE DISK STORAGE • FULLSERIAL RS-232C PORT WITH PROGRAMMABLE BAUD RATES AND MODEM CONTROL SIGNAL • DEDICATED DISK PORT •PRINTER PORT SUPPORTS PARALLEL COMMERCIAL PRINTERS • 24 PIN I/O USER PORT • PAGEMATE DATABASEAVAILABLE • PLM COMPILER AVAILABLE • BUSINESS PACKAGES AVAILABLE • COMPLETE DIAGNOSTICS & SCHEMATICSINCLUDED • COMPLETE USER MANUAL INCLUDED

SPECIAL DEALER PRICING AVAILABLE ON DEMONSTRATION

MINIMAX AND SOFTWARE PACKAGES TO QUALIFIED

SELECTED DEALERS. CONTACT NEECO FOR INFO.

PRINTER NOTINCLUDED IN PRICE

THE MINIMAX WAS DESIGNED AND IS MANUFACTURED BY COMPUTHINKCOMPUTER CORP. DISTRIBUTED IN EUROPE AND THE EASTERN U.S. BY NEECO.

IN ADDITION TO HARDWARECAPABILITIES THAT ARE UNMATCHED IN THE INDUSTRY, THE MINIMAXCOMPUTER SUPPORTS A COMPLETE DATA BASE SYSTEM (PAGEMATE), CONTAINING FULLSTATISTICAL, SORTING, AND EDIT FUNCTIONS. A PLM COMPILER IS AVAILABLE, FULL BUSINESSSUPPORT SOFTWARE IS AVAILABLE AND MORE!—FULL DEALER SUPPORT IS AN IMPORTANTPART OF OUR MARKETING. CONTACT NEECO FOR FURTHER INFORMATION.

THE MINIMAX IS NOW AVAILABLE FOR QUANTITY DELIVERY. DOMESTIC DEALERSHIPS AVAILABLE.

EUROPEAN DISTRIBUTORSHIPS/DEALERSHIPS AVAILABLE TO QUALIFYING COMPANIES WITH

SUPPORT CAPABILITIES. SOFTWARE HOUSES AND OEM INQUIRIES INVITED. CONTACT NEECO.

NEECO

NEW ENGLAND ELECTRONICS CO., INC.

679 HIGHLAND AVE., NEEDHAM, MA 02194

MON-FRI, 9:00-5:30, E.S.T.

(617)449-1760

TELEX 951021, ANSWERBACK "NEECO'

94 BYTE September 1979

Circle 281 on inquiry card.

NEECO

PET 2001 — 32K

PROUDLY ANNOUNCES THE NEWEST

PET MICROCOMPUTERS BY COMMODORE!

The PET™ is now a truly sophisticated

Business System with theannouncement of these Peripherals.

"he PET'", incwjiar.-ilml -.v-th ine I tunny D.sk air] Printermakm an ideal Business system for most crotessronaiand sfiuciatoct Mils medicine taw, denial resesrctitnginaering loolmaking. ptintmc; education, energy cnnsorvaien, etc The PET™ Business System as an!ati,i(jf;mGnr io:;1 (tolivL'rs >ntarmillion 10 all levels ofBusiness previously aiid'iiaUie only win cquipmeninany limosmoicc(X;nsi«e Tun PET1* BusinessSystem is ore Of Ine most cost OfftOOrt Dusness ion's

lixi.iy it offers ci '.'jiiI'1 r.iniii: ot ;jr,)pi.i-;ikKis tram loggingm;ina;iei'n(ir,t si(,iii>(iy in major rcGrpcrationsioarrjiirioniiaccounts and inventory control of small DuS'nessf.'ij Hereare |usl a tew ot Hie cost- saving uses in ihe cO'poratinnprolessionai office 01 small business slock connolpurchasing. irj:e(:.-isliiH| manuiadiiringcosting.customerrecords, mailing hsls. etc The PET". Floppy Disk andPunier a comoatiDie business system at a reasonablep/ice — Take a closer too-! at mese Fcrinne-ais

LARGE TYPEWRITER KEYBOARDS NOW AVAILABLE!

PRODUCT DESCRIPTION

PET 2001— 4K 4K RAM

PET 2001— 8K 8K RAM

PET 2001 —16KN (Large Keys)16K RAM*PET 2001—32KN (Large Keys)32K RAM

PET 2023 PRINTERPET 2022 PRINTERPET 2040APET 2040PET C2N

ROLL FEED

TRACTOR/ROLL

SINGLE FLOPPY

DUAL FLOPPY*

2nd Cassette

"The 16K/32K (large keyboard) units do not include a cassette drive. Order C2N Cassette2040 Floppy Drive requires a 16K or 32K unit. 8K RAM Retrofit available July.

PRICE$ 595

$ 795$ 995$1295$ 850$ 995$ 895$1295$ 100

AVAILABILITY

IMMEDIATEIMMEDIATEIMMEDIATEIMMEDIATEIMMEDIATEIMMEDIATEJUNE/JULYIMMEDIATEIMMEDIATE

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BYTE September 1979 95

The Nature of Robots

Part 4: Looking for Controlled Variables

William T Powers

1138 Whitfield Rd

Northbrook IL 60062

In this last part of my series ofarticles, a simple experiment with ahuman subject will be attempted; anexperiment that can be expandedalmost indefinitely. All of the prin-ciples from the previous parts will beused. Before the experiment starts,note the following main points thathave been established:

• The behavior of an organism is notits output, but some consequenceof its motor outputs actingtogether with unpredictable forcesor other disturbances.

• For a more or less remote conse-quence of motor outputs to berepeatable in a disturbance-proneworld, the behaving system mustsense the consequence, and act tokeep it matching some static ordynamic reference condition. Bydefinition, that makes theorganism a control system.

• Organisms acting as controlsystems control what they sense,not what they do.

• What is controlled is what issensed, even when the sensing in-volves one or more stages of real-time computations based onprimitive sensory signals.

• In a multiple-level control system,the higher levels act by varying thereference signals for lower-levelsystems. They control perceptionscomputed from many lower-levelperceptions, some or all of whichare controlled by the same lower-level systems.

• If there are n degrees of freedom atone level of control, in principle nhigher-level systems could act in-dependently and simultaneouslyby sharing the use of the lower-level systems. Any higher-level

system acts by sending amplifiedcopies of its error signal to manylower-level systems, each with theproper sign to achieve a negativefeedback effect. Any lower-levelsystem receives a reference signalthat is the net effect of super-imposed higher-level outputsignals. This worked for a 2-levelsystem with 3 control systems ateach level; there is no limit, inprinciple, to the number of levelsor the number of systems at eachlevel. In practice, there is reason toanticipate finding hundreds ofsystems at a given level, but nomore than 10 or 12 distinct levelsin a human being. This will becommented on later.

Abstract models and simulationsare fine for conveying general ideas.However, if one does nothing butmake models and simulations, it iseasy to get involved in the math andengineering, and forget the real thingis there to be seen. Items described inthe first 3 articles in this series repre-sent something real. Real organismswork much the same way controlsystems work. They do not work inany of the other ways that have beenproposed over the centuries (as far astheir behavior is concerned). I am nottalking metaphorically. There are ex-cellent reasons to think that when theproperties of organisms begin to beinvestigated in terms of controltheory, hard data about the way weare organized will start to accumulate(up to a point, anyway).

The experiment to be described inthis article is so simple that it maylook elementary. Nevertheless, it isthe starting point for a new approachto exploring the organization of

human beings. Most new ideas startby looking like old ones, but with atwist that leads in unexpected direc-tions. If you are familiar with track-ing experiments, do not be too quickto decide what this is all about.

Equipment Required

The basic equipment needed to dothis experiment is:

• A joystick with 1 degree offreedom (ie: a potentiometer witha stick on the shaft will suffice).

• A reasonably fast analog-to-digital(A/D) converter with 7-bit ormore accuracy. My system usesthe Cromemco D + 7A, which has7 analog channels in and 7 out, aswell as 1 input and 1 output 8-bitport.

• A memory-mapped display, inwhich points are plotted on a videoscreen by depositing appropriatecodes in a reserved segment ofmemory. This, or somethingequivalent, is essential for creatingthe moving objects that are involv-ed in the experiment. I use thePolymorphics VTI with the displayarea in the 1 K bytes of memorystarting at hexadecimal locationD000. Out of deference to systemsthat do not have the VTI's graphicscapability (however crude), I haveused 64 horizontal elements in thealphabetic mode. Higher resolu-tion would be much more desir-able, but this much is enough toshow the principles well.

If no memory-mapped display isavailable, but 2 digital-to-analog(D/A) outputs and a triggeredoscilloscope are, the display that isneeded can be created. Use 1 D/A

96 Seplember 1979 © BYTE Publications Inc

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7M89BYTE September 1979 97

converter to deflect the trace in the Ydirection, and the other (or 1 bit of adigital port) to trigger the sweep. Bystarting the sweep and then out-putting the 3 cursor values in se-quence, a 3-segment trace can becreated, with the motion of the cur-sors being up-and-down instead ofside-to-side, as in the following pro-gram. Lay the oscilloscope on its sideif that deviation bothers you.

Systems with built-in graphicsunder BASIC control, such as Apple,PET, or TRS-80, will probably allowthe experiment to be done moresimply than how I did it in listing 5.The basic requirement is to be able toread a number from a stored table,add the handle position to it, erasethe old cursor, and use the sum toposition the new cursor, doing thisfor 3 cursors at least 4 times per se-cond - the faster the better. (An exam-ple of the simulation on the Apple IIis shown in listing 6.)

Experimental Design

Imagine a display with 3 cursors onit, one above the other. Each cursorcan move left and right. The subjectlooks at this display while holding acontrol handle. The instructions forthe first experiment are very simple:the subject is asked to select 1 of thecursors, and hold it still, somewherenear the center of the screen as ac-curately as possible for the duration

North Star Strings

The North Star BASIC string expressionB$(I,J) corresponds to MID$ (B$,IJ) in otherversions of BASIC. B$(I) corresponds toRICHT$(B$,I), and B$(1,I) corresponds toLEFT$(B$,1,I).

of the run. Engineering psychologistscall this "compensatory tracking."They use it to investigate the limits ofspeed and accuracy of control in thepresence of rapid disturbances ofvarious kinds.

If the handle is held centered, eachcursor will be seen to wander backand forth in a pattern that is indepen-dent of the other 2 cursors. In this ex-periment, the disturbances causingthis wandering are made very slowand smooth. With even a slightamount of practice, every subject willbe able to maintain essentially perfectcontrol. Transfer functions will notbe measured, nor will the limits ofcontrol be tested in the manner tradi-tional in engineering psychology. Asubject acting well within the range ofnormal operations under conditionswhere the phenomena of control canbe clearly seen is desired. The subjectselects a visual variable (position of 1of the cursors), selects a referencelevel for that variable (a particularposition), and maintains the perceiv-ed position at the reference position,while disturbances act that tend tomove the cursor away from thereference position.

Figure 17 shows the setup inschematic form. The 3 disturbancesare labeled Dl, D2, and D3. The 3cursor positions are labeled Cl, C2,and C3. The position of the controlhandle is H. The position of each cur-sor is determined by the sum of H andone of the Ds. For cursor 2 the effectof the handle is reversed, so the 3relationships are:

ClC2C3

Dl + HD2 - HD3 + H

If the subject controls C3 in rela-tion to a reference position of 0 (ie:midscreen), and does so perfectly,then 0 = D3 + H, or H=-D3. Thehandle position should be an accuratemirror image of the magnitude of thedisturbance D3 at every moment, andthe cursor C3 does not move at all.You will find that all subjects, after alittle practice, will closely approx-imate these predictions.

This may seem elementary, ob-vious, boring and hardly worth thelabor of getting the experiment upand running. Do not be deceived; thisexperiment appears to be simplebecause it is fundamental. It is fun-damental because it can prove that allof the life sciences have been using thewrong model. There are also severalextensions of the experiment that willshow how to get started mapping thewhole hierarchy of human controlsystems. There is no theory and nosimulation that carries the impact ofseeing how a real living controlsystem works; especially when youcan understand every detail of what ishappening, either as subject orobserver. The 3 previous articles inthis series have been designed to givethe ability to grasp what is happeninghere. This experiment is designed togive the gut feeling of knowing.

Program Structure

The program in listing 5 is writtenin North Star BASIC, Version 6,Release 3. It contains a machine-language subroutine for an 8080/Z80

Text continued on page 102

Figure, table, and listing numbering continuedfrom part 3.

Z=RMD(A/100)

Listing 5: North Star BASIC control-variable simulation. The necessary assembly language routines needed for execution are alsogiven.

10 DIM H$(16),D1$(250),D2$(250),D3$(250),H1$(250),F$<82),S$(82)

20 DIM A$(2)

30 H$="0123456789ABCDEF"

40 INPUT "SEED FOR RANDOM GENERATOR (1 - 100) ",A\

50 REM *******************************

60 REM CONVERT 2 HEX DIGITS TO DECIMAL

70 REM *******************************

80 DEF FNB(AS)

90 U=ASC(A$(1,1))\IF U<58 THEN U=U-48 ELSE U=U-55

100 V=ASC(A$(2,2))\IF V<58 THEN V=V-48 ELSE V=V-55

110120

RETURNFNEND

16*U+V

98 September 1979 © BYTE Publications Inc

REMREMREMINPUTGOSUB!"6 SM1 = 25DATADATADATADATAM = M1READFILLREMREMREMFILLFILLFILLFILLREMREMREMINPUTGOSUBFILLFILLREMREMREMW = 3*3\!"T"T\P"F

***********************************

SET MACHINE-LANGUAGE PROGRAM ORIGIN***********************************

"MOST SIG. BYTE, SUBROUTINE LOCATION: ",SS

1130EC TO LOAD SUBROUTINE"6*A0\ M2=Ml+9

"0200000000000000004BDB19071F1F4 73A0800FE00C21C00782F""3C477881E63F4F2A00003A08003C3CFE0 6DA2F00AF""320800856F5E23563EA0127BE6C0B15F3EAA12722B73DB19EE80""6F2600C9"

!\

!\

!\

!\

!\

! \

N1=32

FOR J

D1SCJ

D3$(J

NEXT

i »

N3^25IF J-R1 = R1NEXTINPUTFOR JREMREMREM! \! \!GOTOFOR IFILL

B$\FOR

M,A\ M

*****

INSER*****

M1+1,AM1+FNBM1+FNBM1+FNB*****

SET L*****

"MOST

1130

M1+2,F

M1+6,F

*****

LOAD*****

.14159A!\!\

HE SCRHEN THICK ONOR THE

\ N2=3= 1 TO,J)=CH,J)=CHJ

CLOA\FOR JN3*INT+CRO-RJ

"READY= 1 TO*****

EXPER*****

\GOSUB690= 1 TO

M1+8,4

J = 1 TO LEN(B$)-1 STEP 2\ A=FNB(BS ( J,J + 1))= M + 1\NEXT J\ IF AO201 THEN 250******************

T RELOCATION BYTES******************

0\ FILL M1+FNB("12"),A0

("17"),A0\ FILL M1+FNB("23"),A0

("2D"),A0

("26"),A0\ FILL M1+FNB("31"),A0

********************

OCATIONS FOR DISPLAY********************

SIG. BYTE, DISPLAY LOCATION: ",S$

NB("CO")\ FILL M1+3,A0\ FILL M1+5,A0+2NB("40")\ FILL M1+7,A0+3******************

DISTURBANCE TABLES******************

27/250\R0=RND(0)\Rl=32*R2=Rl

CONE MINUTE TO LOAD DISTURBANCE

EEN WILL CLEAR AND THREE

REE CURSORS WILL APPEAR,

E CURSOR AND TRY TO HOLD

DURATION OF THE RUN, AS

CSTAND BY FOR PROMPT]"1\ N3=25\ N4=64\ N5=10250

R$(N1+N2*SIN(W*J))R$(64-ABS(J-125)/2)

DING RANDOM DISTURBANCE: STAND BY]"

=1 TO 250

(J/N3)=Q THEN R0=N4*RND(0)

1)/N5\ R2=R2+(R1-R2)/N5\ D2$(J,J)=CHR$CR2)

TO GO: HIT RETURN TO PROCEED. ",A$16\!\NEXT***********

IMENTAL RUN***********

680\!\!\!\!AGOSUE 680\!\!\!\!\GOSUP 6R0\!\!

8\!"TTTTTTT+",\NEXT I\ RETURN

\ REM SYNCH CURSOR COUNTER

tables:"scales will appear."one for each scale."it in one position"exactly as you can."

Listing 5 continued on next page

September 1979 © BYTE Publications Inc 99

700 N1=8\N2=127\N3=128\ FOR J=1 TO 250

710 FOR L=1 TO 4

720 OUT 25,N2\ OUT 26,N3

730 H=CALL(M2,ASC(D1$(J,J)))

740 H=CALL(M2,ASC(D2S(J,J)))

750 H=CALL(M2,ASC(D3$(J,J)))

760 NEXT L

770 H1$(J/J)=CHR$(H)

780 NEXT J

790 REM *********************

800 REM DATA PLOTTING PROGRAM

810 REM *********************

820 GOSUB 1050\ IF Y0<1 THEN 560

830 !"AFTER PLOT, HIT RETURN TO CONTINUE"

840 INPUT"WHICH CURSOR (1,2,3)? ",I

850 IF 1=0 THEN 560

860 FOR W=1 TO 250 STEP INT (250/CYO+1))

870 H=(ASC(H1$(W,W))-128)*X0/128

880 ON I GOTO 890,900,910

890 V=ASC(D1$(W,W))-32\ GOTO 920

900 V=ASC(D2$(W,W))-32\ H=-H\ GOTO 920

910 V=ASC(D3$(W,W))-32

920 V=V*X0/64+1

930 C=V+H+ZO\ IF C<1 THEN C=1\ IF OXO THEN C=XO

940 V=V+ZO\IF V<1 THEN V=1\ IF V>XO THEN V=XO

950 H=H+ZO\ IF H<1 THEN H=1\ IF H>XO THEN H=XO

960 B$=S$\B$(ZO,ZO)="."

970 !#TO,\B£(V,V)="D"\ B$(H,H)="H"\ B$(C,C)="C"

980 U=0\ IF V>U THEN U=V\IF H>U THEN U=H\IF OU THEN U=C

990 IF ZO>U THEN U=ZO\B$=B$(1,U)\ !#TO,P$,

1000 NEXT W

1010 INPUT1"",A$\ GOTO 820

1020 REM ********************************

1030 REM SET UP FOR PLOTTING (SUBROUTINE)

1040 REM ********************************

1050 !\INPUT "Y-DIMEflSION OF PLOT (0 = NEW RUN): ",Y0\ Y0 = Y0-2

1060 IF Y0<1 THEN RETURN

1070 INPUT "X-DIMENSION OF PLOT (1-72): ",X0

1080 IF X0>72 THEN 1070\ IF X0<1 THEN 1070\X0=X0-2

1090 INPUT "OUTPUT DEVICE (T OR S)",A$

1100 IF A$="T" THEN T0=2 ELSE T0=0

1110 SS = ,,M\FOR 1 = 1 TO XO\S$ = S$ + " "\ NEXT I

1120 Z0=INT(X0/2)\ RETURN

1130 REM **********************************

1140 REM CONVERT HEX IN S$ TO DECIMAL IN AO

1150 REM **********************************

1160 A0=0\K = 1\F0R J = 1 TO LEN(S$)-1\K = K*16\MEXT J\K = INT (K + .01)

1170 FOR I = 1 TO LEN(S$)

1180 FOR J=1 TO 16

1190 IF S$(I,I)=H$(J,J) THEN EXIT 1220

1200 NEXT J

1210 !"NOT HEX NUMBER"\ EXIT 160

1220 AO = AO + K*(J-1)\ K=K/16

1230 NEXT I

1240 RETURN

1250 REM *******************************

1260 REM UTILITY, CONVERT HEX TO DECIMAL

1270 REM UP TO TEN HEXADECIMAL DIGITS

1280 REM DO "RUN 1300"

100 September 1979 © BYTE Publications Inc

1290 REM *******************************

1300 DIM HS(16)\H$="0123456789ABCDEF"\!

1310 INPUT1"HEX= ",S$\G0SUB 1160\!" DECIflAL= ",A0\GOTO 1310

001

*

MACHINE LANGUAGE

002

*

003

ORG

0

004

*

005

0000

0200

ADRO

DBL

ADR1

006

0002

0000

ADR1

DBL

0

007

0004

0000

ADR2

DBL

0

008

0006

0000

ADR3

DBL

0

009

0008

00

COUNT

DATA

0

010

0009

4B

START

MOV

C,E

011

OOOA

DB19

IN

25

012

OOOC

071F1F

ARS

013

OOOF

47

MOV

B,A

014

0010

3A0800

LDA

COUNT

015

0013

FE02

CPI

2

016

0015

C21C00

JNE

S1

017

0018

78

MOV

A,B

018

0019

2F

CMA

019

001A

3C

INR

A

020

001B

47

MOV

B,A

021

001C

78

S1

MOV

A,B

022

001D

81

ADD

C

023

001E

E63F

ANI

:3F

024

0020

4F

MOV

C,A

025

0021

2A0000

LHLD

ADRO

026

0024

3A0800

LDA

COUNT

027

0027

3C

INR

A

028

0028

3C

INR

A

029

0029

FE06

CPI

6

030

002B

DA2F00

JLS

S2

031

002E

AF

ZAR

032

002F

320800

S2

STA

COUNT

033

0032

85

ADD

L

034

0033

6F

MOV

L,A

035

0034

5E

MOV

E#M

036

0035

23

INX

H

037

0036

56

MOV

D/M

038

0037

3EA0

MVI

A,:AO

039

0039

12

STAX

D

040

003A

7B

MOV

A,E

041

003B

E6C0

ANI

:C0

042

003D

B1

ORA

C

043

003E

5F

MOV

E,A

044

003F

3EAA

MVI

A,:AA

045

0041

12

STAX

D

046

0042

72

MOV

M,D

047

0043

2B

DCX

H

048

0044

73

MOV

M,E

049

0045

DB19

IN

25

050

0047

EE80

XRI

:80

051

0049

6F

MOV

L,A

052

004A

2600

MVI

H,0

053

004C

C9

RET

SUPPORT ROUTINES

GET HANDLEDIVIDE BY TWOSAVE IN BCHECK FOR MIDDLE

ONE

IF MIDDLE ONE NEXT,MAKE HANDLE NEG.(TWO'S COMPL.)

X=X+HANDLELIMIT TO 63SAVE X IN CGET BASE ADDRESSGET DISPLACEMENT

BUMP TWICE

CHECK MODULO 6

MAKE ADDRESS FORCURRENT CURSOR.

DE=OLD SCREEN ADR.LOAD A SPACEERASE OLD CURSOR

ZERO DISPLACEMENT

NEW DISPLACEMENT

POINTER FIXED

LOAD ASTERISK CURSOR

PUT IT ON SCREEN

SAVE CURSOR

ADDRESS

GET HANDLE AGAINRANGE 0-255

September 1979 © BYTE Publications Inc 101

5

HIMEM: 8192

10

DIM D1 %(250),D2%(250),D3%(250),H1 %(250)

20

INPUT "SEED (0-100): ";A

30

Z = RND(A/ 100)

40

REM LOAD DISTURBANCE TABLES

50

W = 3 . 3.141592654 / 250

60

R0 = RND(0):R1 = R2 = 140

65

PRINT : PRINT : PRINT : PRINT : PRINT : PRINT : PRINT : PRINT

70

PRINT : PRINT : PRINT "LOADING DISTURBANCE TABLES"

75

PRINT

80

PRINT "WHEN SCREEN CLEARS, BACKROUND WILL"

85

PRINT

90

PRINT "APPEAR — THEN THREE CURSORS."

95

PRINT

100

PRINT "PICK ONE CURSOR AND HOLD IT IN"

105

PRINT

110

PRINT "ONE POSITION FOR THE DURATION OF"

115

PRINT

120

PRINT "RUN, AS ACCURATELY AS YOU CAN-

125

PRINT

130

PRINT "STAND BY FOR PROMPT MESSAGE"

140

FOR J = 1 TO 250

150

D1%(J) = 140 + 130 * SIN (W , J)

160

D3%(J) = (125 - ABS (J • 125)) . 270 / 125

170

NEXT J

175

PRINT

180

PRINT "RANDOM DISTURBANCE LOADING: STAND BYE."

185

N3 = 25:R1 = 140:R2 = 140

190

FOR J = 1 TO 250

200

N3 = N3- 1: IF N3 > 0 THEN 210

205

N3 = 25:R0 = 280 . RND (5)

210

R1 = R1 + (R0 ■ R1) / 05:R2 = R2 + (R1 - R2) / 5

220

D2%(J) = R2

230

NEXT J

240

PRINT : INPUT "HIT RETURN FOR RUN";A$

250

HGR

255

HCOLOR= 3

260

POKE 49234, 0

261

FORX = 1 TO 280 STEP 10

262

FOR Y = 43 to 143 STEP 50

263

HPLOTX.Y: HPLOT X,Y 4- 14

264

NEXT Y: NEXT X

270

FOR J = 1 TO 250

280

FOR K = 1 TO 4

290

H = PDL(0)- 128

299

HCOLOR = 0: HPLOT C1 %, 45 TO C1 % ,55: HCOLOR = 3

300

C1% = D1%(J) + H

305

IF C1% < 0THEN C1% = 0

306

IF C1 % > 279 THEN C1 % = 279

307

HPLOT C1 %,45 TO C1 %,55

309

HCOLOR= 0: HPLOT C2%,95 TO C2%,105: HCOLOR= 3

310

C2% = D2%(J)- H

315

IF C2% < 0THEN C2% = 0

316

IF C2% > 279 THEN C2% = 279

317

HPLOT C2%,95 TO C2%,105

319

HCOLOR = 0: HPLOT C3%, 145 TO C33%, 155: HCOLOR = 3

320

C3% = D3%(J) + H

325

IFC3% < 0THENC% = 0

326

IFC3% > 279 THEN C3% = 279

327

H PLOT C3 %, 145 TO C3 %, 155

370

NEXTK

380

H1%(J) = H

390

NEXT J

400

HGR

405

POKE 49234, 0

410

FOR J = 1 TO 250

420

Y = 191 - J * 191 /250

430

U = 88 / 280

435

H = INT (H1 %(J) , U)

440

D1 = INT((D1%(J)- 140) . U + 45)

450

D2 = INT (D2% J) - 140) * U + 135)

460

D3 = INT((D3%(J) - 140) . U + 225)

461

C1 = D1 + H:C2 = D2 - H:C3 = D3 + H

462

IFC1 < 0THEN C1 = 0

463

IF C3 > 278 THEN C3 = 278

480

HCOLOR= 1

490

HPLOT D1,Y: HPLOT D2,Y: HPLOT D3,Y

500

HCOLOR= 2

510

HPLOT C1 ,Y: HPLOT C2,Y: HPLOT C3,Y

520

HCOLOR= 3

530

HPLOT H + 45,Y: HPLOT ■ H + 135,Y: HPLOT H +225.Y

540

NEXT J

550

INPUT "";A$

560

TEXT

570

GOTO 180

Listing 6: A computer such as the Apple IIwhich has high-resolution graphics capa-bilities greatly simplifies the programoriginally given in listing 5. This programperforms the same operations as the simu-lation in listing 5. The author acknow-ledges the assistance of Charles Faso fromComputerland of Niles IL in preparingthis program.

Text continued from page 98:

processor which is loaded by theBASIC program at any specified256-byte memory-address boundary(specify in hexadecimal only themost significant byte of the locationof the subroutine).

The machine-language subroutinereads in the handle position, adds itwith the appropriate sign to the valueof a disturbance that is passed to thesubroutine by the CALL command(in the DE register pair), erases theold cursor, and deposits the new cur-sor, a rubout, on the screen. Eachtime the subroutine is called it steps tothe next cursor, recycling asnecessary. On return from thesubroutine, the handle position ispassed back to the main program (inthe HL registers). The machine-language program is in lines 200 thru230, expressed as a string of hex-adecimal bytes with no punctuation.Thus if your machine is not an8080/Z80 type, a program can beassembled, the listing copied intothese lines, and possibly this programcan be made to work with little othermodification.

The program asks for the mostsignificant byte of the place where themachine-language subroutine isstored. The loader adjusts memoryreferences by inserting the value ofthis byte in memory wherevernecessary, after the program is loaded(lines 300 thru 330).

The display area consists of 1 Kbytes of memory starting on any256-byte boundary. Lines 370 thru400 ask for the starting location of thememory area devoted to the display,and set up base registers in themachine-language program for theleft margin of each cursor's move-ment. The FILL command is likePOKE. If the computer has graphicscapability built-in, everything fromline 60 thru 400, and the plottingsubroutine (later), can be accomplish-ed in a simpler way.

Disturbance tables are set up inlines 510 thru 620. The unnecessaryuse of symbols, instead of constants,

102 September 1979 © BYTE Publications Inc

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Figure 17: Schematic arrangement of experimental setup. Three slow and smooth distur-bances are added to a measure of the handle position (with a negative sign for themiddle one), to determine the position of 3 corresponding cursors. The subject selects 1cursor and a reference position for it, and uses the handle to maintain the cursor at thatposition. A run lasts about 1 minute, and 250 samples of handle position are recorded.For plotting, the cursors are reconstructed from the tables of disturbances and thecorresponding records of handle position.

is an attempt at acceleration. It stilltakes a minute to load the 3 distur-bance tables, each 250 bytes long. Alllong tables are strings; only 8 bits ofaccuracy is needed, so by using theCHR$ and ASC functions, the tablescan be stored 1 byte per value insteadof 5 bytes per value. Disturbances arein tables because BASIC cannotcalculate them fast enough.

Disturbance Dl is a sine wave andD3 is a triangular wave. D2 is asmoothed random disturbance. Onreruns, only D2 is reloaded, takingabout 20 seconds.

The experimental run is controlledby lines 660 thru 780. Lines 660 and680 lay down 3 arbitrary scales on thescreen, while the rest repeatedly callthe machine-language subroutine. Foreach stored value of each distur-bance, all 3 cursor positions are com-puted and plotted, and the handleposition is stored in the table Hl$.The inner loop from line 710 to line770 adjusts the duration of the ex-perimental run; here it is set up sothat the disturbances change and ahandle position is recorded onlyevery fourth time the display isgenerated. On my system, this worksout so the display is refreshed 16times per second, and data is sampledand stored 4 times per second. The 2OUT statements reflect my laziness; Iuse 2 digital-to-analog outputs tosupply the voltage to the poten-tiometer that measures handle posi-tion.

The data plotting routine (lines 820thru 1010) is entered at the end of anexperimental run. This routine is setup to plot either on the video screen

or on a hard-copy device; it asks forthe X and Y dimensions of the plot,which cursor is to be plotted, andwhich device is to be used. My systemis set up so the typewriter is device 2and the screen is any other devicenumber. If you do not have thisability in your BASIC or system,delete lines 1060 and 1070 (in thesubroutine that requests informationabout the display), and eliminate the"#2," in lines 970 and 990. In NorthStar BASIC, the exclamation point isshort for PRINT.

Only the handle position is storedas data; the cursor positions arereconstructed during plotting fromthe list of handle positions and thecorresponding tables of disturbances.

The plotting scheme is designed towork with any teletypewriter-likedevice. If you have legitimategraphics, you can rewrite this partand get a more pleasing result.

There are 3 choices for plotting,each associated with cursors Cl, C2,and C3. Each plot shows the cursor asa C, the handle position as an H, andthe disturbance acting on the cursoras a D. A dot indicates the center ofthe display when nothing else is there.After each plot is finished, there is apause; hitting the carriage return willcause the program to ask about thenext plot. If the question about the Ydimension of the display is respondedto with a 0, the program will reloadthe random disturbance table andissue a prompt for another ex-perimental run. The old data will bedestroyed. Remember, it takes about20 seconds to reload the randomdisturbance table. Do not panic if

104

September 1979 © BYTE Publications Inc

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BYTE September 1979 105

there is a long pause.

At line 1260 there is a utilityroutine that converts any hex-adecimal number up to 10 digits to adecimal number. I used it whilewriting the program. It calls the con-version subroutine starting at line1130.

Running the Experiments

If you possibly can, take thetrouble to set this experiment up.Nothing can take the place of actuallyexperiencing yourself as a controlsystem and understanding things thatyou have taken for granted all yourlife.

Here is a typical run for the benefitof the many readers who do not havethe equipment to do this; the data willthen be observed. Here is an oldfriend, Chip Chad (from part 1 of thisseries), glaring at the screen andmaintaining a choke-hold on thehandle, waiting for the experimenterto hit the return key at line 610. Theexperimenter reaches in and taps thekey. The reference scales slide up intoplace and the 3 cursors pop into view,moving. Chip picks the middle one asmost people do the first time, decidesto keep it on the middle + mark, andafter a few wobbles succeeds.

'So what?" he says.

If learning were being studied,good information could be obtainedfrom this first run. But the plan is tosee Chip acting as a competent con-trol system, so his first effort ispraised and he is given another run(answering the query about Y dimen-sion with a 0). After the second run,the data is plotted for each cursor.

Figure 18 shows the data for eachcursor, number 1 on the left, 2 in themiddle, and 3 on the right. The 2 endplots are a mess, but the middle plotshows a striking symmetry. The Csmarch more or less down the centerof the screen, deviating a little to leftand right, but maintaining a constantposition on the average. The Ds makea random-looking pattern, and the Hsfollow almost the mirror image of theD pattern.

Looking carefully at the middleplot, could it be said that the handleposition or motion looks like any sortof regular function of the cursor posi-tion or motion? There may be somerelationship, but it certainly is notclear.Probably, nobody would claimthat the large, smooth motions of thehandle could be reconstructed ac-

curately on the basis of measurementsof cursor position (that is, recon-structed roughly or statistically withaccuracy,especially if handle ac-celeration is compared with cursordeviation from the average position).The best which could be hoped forwould be some statistical relationship(eg: a small signal buried in muchnoise).

On the other hand, the relationshipbetween the handle position and themagnitude of the invisible distur-bance is obvious and quantitative. Itis seen that the handle position is themirror image of the disturbancemagnitude with an error of only a fewpercent of full scale. There is much

signal and little noise in that relation-ship.

Here is the situation. There is 1measure of Chip's behavior, H. Thereare 2 variables, D and C, either ofwhich might have some relationshipto that behavior. Which variable, Dor C, would be selected by anystatistical test as the most probablecause of the behavior? Of course, Dwould be selected. In fact, a formalstatistical analysis, like those done inevery scientific study of behavior,shows D to be the only significantcontributor to the behavior, while C,the cursor position, is rejected as anirrelevant variable!

That is a paradox, however, from

Figure 18: A typical run for a practiced subject. In figure 18a is the record for Dl, Cl,and H. Figure 18b has the record for D2, C2, and H; figure 18c has the record for D3,C3, and H. In figure 18b, the cursor is held near the center, while the handle position isat all times very nearly the mirror image of the disturbance amplitude. It is very easy todecide which cursor was under control.

D

C H

H

C

H

C

H

C

H

D

c

H

D

c

H

D C

H

DCDC

H

DC

H

D C

H

D

C

H

D

C

D

H

C

H

C

H

C

H C

D C

D C

DC

DC

D C

D C

C

106

September 1979 © BYTE Publications Inc

Figure 19: Cause and effect paradox. Under the old concept that stimuli cause behavior,the cause and effect chain runs from the disturbance to the cursor, through the subject,to the behavior. However, the correlation of the disturbance and the cursor position isvery low, as is the correlation of the cursor position and handle position (for the con-trolled cursor). This would lead to a prediction of an even lower correlation of distur-bance and behavior. In fact, that correlation is normally very high (0.99 or better).Only the control theory analysis of this experiment can explain this otherwise paradox-ical situation.

CORRELATION > 0.99

— c-

SUBJECT

CORRELATION < 0.

CORRELATION < 0.1

the traditional point of view. Theonly way D can affect Chip'sbehavior is through its effects on C,since all that Chip can sense is thecursor position. The disturbance itselfis invisible. If C does not correlatewith the behavior, then how cananything that acts exclusivelythrough effects on C correlate anybetter with behavior? Yet a typicalcorrelation between C and H isaround 0.1, while the correlation of Hwith the corresponding D is typically0.995. See figure 19.

That is the proof mentioned earlier.The old cause-effect model failsutterly when applied to this situation.The question then is, why havegenerations of intelligent peoplebelieved that behavior is caused bysensory stimulation? The answer isclear: they have been fooled by amonstrous illusion.

The illusion would be easier to seeif there was some visible, direct in-dication of the magnitude of thedisturbance. Suppose there were amoving D (or a number that con-

tinually reflected the magnitude of D)on the display. Clearly, if Chipmanaged to control C without thatindication, he could still do so; hecould ignore it and perform as well asever. However, something has nowbeen added that would mislead abystander who did not understandcontrol theory.

That bystander could now see 2variables, both able to affect Chip'ssenses. Taking the apparent relation-ships at face value, it would be clearthat the indication of D was accur-

(18b)

„HC .C.i C. D

H .C D

H C. D

H C. D

H C. D

H .C D

H C. D

H C. D

i C D

C

cc.c.

C D

H CD

H CD

D C. H

D C H

D C H

D C. H

D C. H

D CH

CH

0 C. H

D C . H

D C H

D C H

D C. H

) C K

C.

c.cc

) C. H

D C H

D C H

H C D

H C D

H .C D

H C. D

H C. D

H C D

H C. D

HCD

D C. H

D C H

D C H

DC

(18c) CD H

D C.

D C

D C

D C

D C,

DDDDDD

HHH C

H C

H C

H C

H C

H C

HC

HC iDCDD C

D C

D C

D C

D C

DC I

CD H

CD H

CD H

HHC H

C H

C H

C H

C HCHD HC

D H C

D H C

D H C

D H C

H D C

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C DC D

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HHHHH

September 1979 © BYTE Publications Inc 107

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ately associated with the handle posi-tion; while the movements of the cur-sor, such as they are, show no suchassociation. Furthermore, the varia-tions of D are large and smooth, andthere is no observable relationshipbetween D and C. Why should thebystander suspect that C is beingaffected by D in one way and affectedby H in an opposite way? The ob-vious conclusion is that the variationsin D are causing Chip's behavior,while C has nothing to do with hisbehavior, especially if C does notvary more than the fixed backgroundscales do. If the screen were full ofirrelevant cursors, jiggling aroundslightly, how could the bystanderpick C as something of special impor-tance? If BASIC were fast enough, Iwould have included such irrelevantcursors; the point being made herewould then be obvious.

An organism is surrounded by aworld full of variables; variables thatchange within widely diverse ranges.The organism receives many signalsfrom its internal parts, too. In thatsort of situation, if the organism iscontrolling some of the variables, itwill react strongly and smoothly to

any disturbance tending to alter 1 ofthe controlled variables. The result isthat it will seem to be respondingdirectly to the disturbances. Therewill be no obvious indication that it iscontrolling anything at all. There isevery excuse for even the best ofscientists to have observed the rela-tionship between disturbance andbehavior, and to have missed thevery existence of controlled variables.

The name for such disturbances isstimuli. Once in a while, an ex-perimenter must have accidentallypicked a real controlled variable tocall a stimulus, but the chances areagainst that. If an attempt is made tomanipulate a real controlled variable,the organism will have to be strappeddown to keep it from interfering.That is what is done in such cases. Ifthe organism insists on acting like acontrol system, forcibly break theloop and make the organism conformto the theory. As a famouspsychologist said, the theme is"Behave, damn it!" It never occurs tosuch stong-willed individuals thatthey might have the wrong idea aboutwhat is happening.

There is more in this elementary ex-

periment than meets the eye. If allpsychologists were to experience it,and try to meet the challenge of ex-plaining these effects using any stan-dard theory, the result would be atotal collapse of that science, follow-ed by a rebirth. However, many jobswould be threatened. What hashappened instead is that a handful ofpsychologists has supported thistheory, another handful has taken uparms against it, and most haveresolutely ignored it.

I suggest that you run this experi-ment many times with subjects con-trolling all 3 cursors. Every case willshow that mirror-image relationshipbetween D and H and little relation-ship between C and either D or H. Ifthe previous parts of this series arestudied and all the relationships thatmake up a control system thoughtabout carefully, it will be evident thatthere is no other explanation for whatis going on here. If you get nothingelse out of this, you should acquire anintuitive feel for a new theory of howbehavior works. You might evenbegin to understand how to design arobot in a new way.

It is time now to try to fulfill a pro-

108 September 1979 © BYTE Publical

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goesbeyond.

mise implied in part 1, to show howanyone with a home computingsystem can make important contribu-tions to this new science of humannature.The best way this can be doneis to start with the experiment used,and to show how it can be extendedto become a powerful tool for in-vestigating human organization. Themain objective will be to introducethe test for the controlled variable,the nearest approach I know of tomind reading.

More Controlled Variables

Once subjects controlling all 3 cur-sors have been seen, it might seemthat the possibilities of this experi-ment have been exhausted; this is notthe case at all. There are controllablevariables all over that screen; all ofthem can be controlled by the samemeans, movements of the handle in 1dimension. Discovering them is agood way to get out of the habit ofthinking that we simply perceive ourenvironment, and start a new way ofthinking: to recognize that we con-struct perceptions, imposing order onour experiences far more thanrecognizing order. As you will see, a

controlled variable does not have tobe "real" at all.

Here is an example. It is possible toperceive the relative position of anyof the 2 cursors. The handle affectsC2 in a direction opposite to itseffects on Cl and C3, so the relativeposition of Cl and C3 cannot be con-trolled because the handle does notaffect it. However, it is possible tokeep Cl even with C2, or C2 evenwith C3; in fact, it is easy. A plot ofthe results would involve plottingC2-C1 or C3-C2 instead of just C,and D2-D1 or D3-D2 instead of just 1disturbance. The mirror image rela-tionship with H would be as good asever. Do not forget that C2-C1 andC3-C2 are variables. Any value of thevariables can be selected as areference level (eg: Cl to be 1 inch tothe left of C2).

These are examples of higher-levelcontrolled variables. If the subjectcould not perceive the present posi-tions of the cursors, he or she cer-tainly could not perceive theirrelative positions. Relative position isderived from perceptions of in-dividual positions, but not vice versa.In order to control relative positions,

it is necessary to control (or at leastvary) individual positions, but in-dividual positions can be controlledwithout controlling relative posi-tions. These are the relationships onelooks for to map out a hierarchy ofperception and control.

Other relative perceptions can becontrolled. All 3 cursors can be keptlying in a straight line, at least withinthe range where 1 of them does notfall off the edge of the display andpop up at the other edge. Reducingthe amplitude of the disturbanceswould eliminate that problem. Also,the 3 cursors can be made to form anyfixed angle, subject to the samelimitation. There may be more staticpatterns that can be controlled, but Ihave not thought of any. This is, afterall, a simple display.

It is not, however, limited to staticconditions. Suppose the subjectvisualizes a pattern in which 1 cursormoves back and forth slowly between2 limits. This pattern can easily bemaintained, the handle moving justenough to produce it, and enoughmore to cancel the effects of any ofthe disturbances. A similar oscillationcould be maintained for the relative

September 1979 © BYTE Publications Inc 109

variables. This is a still higher-levelvariable, a temporal pattern. Thesubject chooses which temporalpattern to perceive, and what state ofthat kind of pattern to maintain.Control still requires only the use ofthe 1-dimensional effect caused by thehandle.

There is clearly an infinite range ofdifferent temporal patterns, rangingfrom a simple steady motion in 1direction to completely arbitrary mo-tions and rhythms. There is anunlimited number of potential con-trolled variables in this simpledisplay. Anything that can beperceived, and that the handle canaffect in a systematic way, can becontrolled.

For all of these examples of con-trollable perceptions, it is essential toremember that the disturbances areacting all the time. This is not amatter of producing any particularbehavior. The cursor cannot be madeto move slowly back and forth be-tween fixed limits just by moving thehandle slowly back and forth be-tween fixed limits. The handle mightbe moving the wrong way at many

moments, when the disturbance tendsto make the cursor move faster thanthe reference pattern being con-sidered. There is no one-to-one cor-respondence between handle positionor velocity and cursor position andvelocity, because of those ever-present disturbances. Regularities ofbehavior are not being looked athere, but regularities of controlledperceptions. If there were a slowlyoscillating prism between the displayand the subject's eyes, a regular pat-tern of movement of the cursor on thescreen would not be seen. The subjectcontrols the visual image, not thereality. For the higher-level variables,the subject controls some function ofthe visual image (often the controlledvariable could not be found, even onthe retinas).

One could create displays of fargreater complexity, and providemeans of affecting the display thathave more than 1 degree of freedomto explore a staggering range of possi-ble controlled variables. This is whatI suggest be done. The first step in thedevelopment of any new science is ac-quire the facts; here the most needed

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facts concern what variables humanbeings can actually control. What isneeded is a large and simplemindedprogram of recording the obviousand obscure. What is needed is abody of definitions of variables inevery sensory mode that people havebeen able to control. Order andsystem count much less than sheervolume of data at this point. In fact,an unsystematic gathering of datamay be the best kind, since it will notbe constrained by theories aboutwhat people ought to be able to con-trol. Anything which can be a way oftesting is worth testing at this stage.The possibilities are limited only bythe imagination.

We do need some sort of orderingprinciple—some criterion for judgingthe reality of any proposed controlledvariable. This is where the test ap-pears; here is how it works.

Test for Controlled Variables

The first thing to remember wheninvestigating a possible controlledvariable is that in order for somethingto be controllable it has to bevariable. There is neither the meansnor the need to control the existenceof the Empire State Building or theplanet Jupiter. Not all perceptions arecontrolled. Some are just distur-bances; some are just there.

One might think initially aboutcontrolling, for instance, a car.People often speak casually aboutcontrolling things. But what is meantis controlling something about thosethings. A person cannot really con-trol a car; but under proper cir-cumstances its shape, its color, itsprice, its speed, its direction, its park-ing place, its dirtiness, itsdangerousness, its desirability, itsaltitude, or the flatness of its tires canbe controlled. A car, after close in-spection, proves to be composed en-tirely of hundreds or even thousandsof variables. Together they create"car-ness" in our perceptions. In-dividually, or in groups, most ofthem can be affected by one means oranother, and can be controlled if it isworth the effort. You can even makethe car disappear instantly by closingyour eyes. Keep remembering thatwhat is controlled is really a percep-tion.

The first step in applying the testfor the controlled variable is to definea variable. You do not have to knowin advance if it is a controlled

110 Seplember 1979 © BYTE Publications Inc

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BYTE September 1979 111

Circle 305 on inquiry card.

variable; you do not even have toknow where the supposed controlsystem is. All you have to do is topick out something that you know isvariable and "push" on it.

By push I mean to apply a distur-bance that under normal cir-cumstances should have a predictabledirection and amount of effect on thevariable. If I push hard enough on alife-sized statue, it should tilt in thedirection of the push. Perhaps it willtopple in that direction according tothe simple laws of mechanics.

Having selected a variable and ap-plied a push to it, the next step is tomeasure the actual effect of the push.I predict that pushing on this statueshould make it tilt a certain amountin a certain direction. I apply the pushand observe the tilt.

If the actual effect is far smallerthan the predicted effect, commonsense indicates that something mustbe pushing back. If the pushing-backis always just enough to cancel anyamount or direction of disturbance(within some limits), it can be con-cluded that the pushing-back issystematic. The mirror-image effectthat has been observed is what iswanted.

It is necessary to discover what ispushing back, and how it is doing thepushing. Perhaps, examining thestatue carefully, an iron rod is foundsupporting its back from its base. Inthat case, a conclusion is made thatthere were not enough facts to make acorrect prediction of the effects of thepush; the bending moment of the rodshould have been taken into account.But if no simple explanation for thefailure of the prediction is found, onemust look further.

Suppose it is discovered that thebase of the statue seems to movewhen pushed. If there is a push to theeast, the base tilts to the west movingthe center of support east of thecenter of gravity of the statue, andthus creating a counterforce. Supposethis tilt of the base is found to bealways just what is required to offsetthe effects of the push. It can be con-cluded that one may be on the trail ofa control system.

What has been done is to find outsomething about the means of con-trol, the path by which the output ofthe control system, if it exists, mightbe linked to the controlled variable(the angle between the statue'slongitudinal centerline and the ver-

tical). Finding this link is a necessarystep in the test.

That step will usually lead todiscovering the physical controlsystem. Tracing the wires that workthe motors that tilt the base of thestatue, you find a black box a fewyards away from the statue. Thatmay be the control system, or at leastall of it that is not its actuators (whichhave been found).

There is still one step to be taken.You cannot be completely sure of thenature of the control system until youdiscover the variable it is reallysensing. The situation has beenapproached with human prejudices;to me, it seems that the controlledvariable is the orientation of thestatue, a geometric or visual variable.Perhaps that variable is only relatedto the real controlled variable. Whatmust be found now are the sensorsthat the control system is using.

Thinking in visual terms, youmight look for a photocell thatdetects the tilt. Suppose a photocell isfound on a stand near the statue. Thetest calls for breaking this link,preventing the sensing of the statue.The result should be that the effect ofthe push returns to what would bepredicted from mechanical laws. Sothe photocell is covered and thedisturbances are applied again. Whathappens is that the floodlights il-luminating the statue turn on. Thestatue still resists the push—thephotocell was for something else.

By careful searching 4 strain gaugesbuilt into the base of the statue arediscovered. These provide a signalshowing where the center of thrust is,and the wires from the strain gaugesrun over to that black box. Discon-necting the wires shows that now thepush succeeds in tilting the statue. Assoon as its tilt becomes marked, anangry groundskeeper comes leapingout of the bushes and arrests the ex-perimenter. Aha! You may havediscovered another control systemcontrolling the state of the statue.

To recapitulate, the test for thecontrolled variable involves thefollowing steps:

1. Define a variable.

2. Apply various amounts anddirections of disturbancesdirectly to the variable.

3. Predict the expected effects ofthe disturbances, assuming nocontrol system is acting.

4. Measure the actual effect of thedisturbances.

5. If the actual effect is essentiallythe same as the predicted effect,stop. No control system isfound.

6. If the actual effect is markedlysmaller than the predictedeffect, look for the cause of theopposition to the disturbance,and determine that it resultsfrom systematic variations insome other variable. If such acause is found, it may beassociated with the output of acontrol system.

7. Look for a means of sensing thecontrolled variable. If none isfound, stop: no control systemis proven to exist.

8. If a means of sensing is found,block it, so the variable cannotbe sensed. If control is not lost,the sensor is not the right one. Ifno such sensor is found, stop:no control system is proven toexist.

9. If all steps of the test are passed,the variable is a controlledvariable, its state is its referencelevel, and the control systemhas been identified.

To apply step 8 of the test to ourcomputer experiment, cover the cur-sor suspected of being controlled witha cardboard strip. Control should belost. Cover each cursor. The coveredone will never pass the test. The othersteps are easily carried out.

Concluding Remarks

Now it is up to you. You can testcontrolled variables involving inten-sity, sensation, configuration,change, sequence, relationship,strategy, principle, and system con-cepts having to do with visual,auditory, tactile, kinesthetic, andother senses.

Good luck with the programs, andgood hunting for controlledvariables. I will be interested toreceive word about what people aredoing with the information coveredin these articles.■

BIBLIOGRAPHY

Powers, W T, Behavior: The Control otPerception, Aldine Publishing Co, 200 SawMill River Rd, Hawthorne NY 10532, 1973.

112 September 1979 © BYTE Publications Inc

"HOOKS OF INTEREST TO COMPUTER PEOPLE"

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iiiiiiiiiniii iiiiini iiiiiiiiiiiiiiiiiiiini milium mimim iiiiiiiiinii miiiiiiiii i iimimimimii iiinini iiiiim iiiiimi

BYTE News ....

lIlllllllllllilllllllllllllllilllllllltltlllllllllllllllllllllllllllltlllllllllllllllllllllllllElllllllllillllllllllllllllllllllllllllllllilllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllll

S-100 8086 AND Z8000 CARDS COMING: At least 6 S-100 product manufacturers are about torelease 16-bit processor cards for the S-100 bus that use the Intel 8086 and Zilog Z8000. One suchcard has already been announced, a 8086 processor card from Seattle Computer Products Inc,Seattle WA. All will conform to the Institute of Electrical and Electronic Engineers (IEEE) S-100standard that is soon to be adopted. They will work with most 8-bit memory cards using byte-serialread/write. However, for full speed operation you will need either a true 16-bit memory card or amodification of your present memory cards. To modify memory cards requires cutting traces, somerewiring, and adding some logic circuitry.

Microsoft has already announced and demonstrated an 8086 BASIC, and is working on a Z8000BASIC, as well as other 16-bit software. Digital Research is working on a 8086 version of CP/M. Most16-bit software in development will be designed for multiprocessing environments, using real-timeclocks and interrupt-driven user-inputs.

CP/M 2.0 TO BE RELEASED SOON: There is no doubt that the most widely used disk operatingsystem for microcomputer is CP/M, developed by Gary Kildall of Digital Research, back in 1974.Although originally written for the Intel 8080 development system, it was adapted to run on 8080,8085 and Z80 systems of many types. Its power and flexibility puts microcomputers in the big leaguesby providing features and capabilities normally found on the bigger models.

Gary Kildall is planning to release the 1st major revision to CP/M (Version 2.0). It will use a real-time clock and be interrupt-driven. It will support all present CP/M software. Look for its releasearound September 1st.

RANDOM RUMORS: Matsushita Inc is rumored to be working on a $250 printer which will generate"letter quality" type. It will print at 15 characters per second and include a keyboard. Rumors aboutHewlett-Packard's Personal Computer are getting warmer. It may be introduced in time for theChristmas market. Expected to sell in the $2500 area, it will have a 5-inch black and white monitor,16 K bytes of programmable memory, BASIC in read-only memory, a built-in thermal printer andcassette I/O (input/output). Texas Instruments is developing a 3 or 4-inch Winchester-type disk driveto sell for approximately $50. Shugart is about to start delivery on the $70 5-inch floppy disk drivemade by Matsushita. Infoton, a video terminal manufacturer, is rumored to be about to introduce avideo terminal which will sell for less than $400 in large quantities. It will use the Zilog Z8 micro-processor and have a total of only 16 integrated circuits. All circuitry will be on 1 printed circuitcard, the power supply will be transformerless, and a special elastomeric keyboard will be used.

HAND-HELD COMPUTER IN DEVELOPMENT: Matsushita Electrical of Japan and Friends-Amis Incof CA have agreed to develop and produce "the first practical hand-held personal computer." Thesize of a hand-held language translator, the unit could be in production by the end of the year. Thecomputer will be able to accept preprogrammed and user programmed memory capsules. Prepro-grammed capsules will include information on business, science, language, education, etc. Thecomputer will have modular construction, enabling new technology modules to be added as they areintroduced. Add-ons will include a miniprinter, miniature video display, and a voice synthesizer.

MICRO-MOUSE CONTEST FINALLY ENDS: The 2 year long "Amazing Micro-Mouse Contest" runby the IEEE has finally ended. Although several thousand entries were received, less than 100actually ran the maze. The contest's objective was to design a robot-type device which couldnegotiate and learn a maze as it went through. The trials were held at conventions of the IEEE, NCCshows and PC-78.

The ultimate winner was entered by the team of Howard P Katseff and Roy Tramwell from BellLabs, Holmdel NJ. Their mouse ran the 8'/2 by 8'/2-foot maze in just under 30 seconds. It employed aZ80 microprocessor with 4 K bytes of read-only memory and 1 K bytes of programmable memory.Second prize was taken by the team from Batelle Memorial Institute of Richland WA. Art Boland,Ron Dilbeck and Phil Stover's mouse ran the maze in just over 31 seconds. One high performer wasactually nonprocessor controlled, and ran the maze in just under 40 seconds.

September 1979 © BYTE Publications Inc 115

VOICE-OPERATED TV DEMONSTRATED: Sanyo Electric Co recently demonstrated a televisionreceiver that responds to voice commands to turn on and off and switch stations. Utilizing a micro-processor, the unit compares the voice input to voice patterns stored in memory. The unit has a 30-word vocabulary, and can respond to the voices from 2 different people. Furthermore, the voiceinput can be used to play games. Sanyo has not announced any immediate plans for incorporatingthe receiver into its television sets.

APL FOR MICROCOMPUTERS: Despite a report in an earlier BYTE NEWS column, Quark hasdecided against introducing its APL microcomputer using the Intel 8086 microprocessor.

JAPANESE MOVING SWIFTLY INTO MICROCOMPUTERS: At least 9 Japanese manufacturers arepresently manufacturing microprocessor integrated circuits. Approximately 80 different micro-processors are being made. Most of them are original designs including advanced features (eg:analog-to-digital converters, multiply/divide, counter/timers, etc). Five different 16-bit micro-processors are already in production. Furthermore, over a dozen personal computers/trainers are inproduction to support a very strong interest in personal computers in Japan. Thus far only a fewunits are available for export.

MOTOROLA ANNOUNCES 68000 DELIVERY AND PRICES: Motorola has announced that it expectsto start shipping limited sample quantities of its new 68000 16-bit microprocessor by the end of theyear. Single unit price will be $249. Limited production quantities are expected to be available bythe end of the 1st quarter of 1980, with full production by late 1980. No second source arrangementshave been finalized.

75 MEGABYTE WINCHESTER DRIVE RUMORED: At least 6 companies exhibited 8-inchWinchester-type drives at the recent NCC show. All of the drives could fit into the same space as an8-inch floppy disk drive, and provided from 10 to 45 M bytes of storage. At least 8 companies will bedelivering these drives by the end of the year, and a 75 M byte version is expected next year. Thedrive should sell for under $2000 in quantity.

PERSONAL COMPUTER MANUFACTURERS RANK WITH COMMERCIAL DATA PROCESSORS:Datamation magazine, in their most recent annual report of the top 50 US companies in the dataprocessor industry, disclosed some interesting facts about changes in the computer industry. For the1st time a personal computer manufacturer, Tandy, ranked among the top 50 in computer equipmentsales, and Commodore ranked second among fastest growing companies. Commodore had a 190%increase in sales in 1 year, to $75M. Tandy(ranked 43rd)reported computer sales of $105M and totalcompany sales of $1,152M resulting in a net income of $76M. The company reported a sales gain ofonly 11.6% (which is about equal to the rate of inflation, and hence could be considered 0 salesgrowth). If Commodore continues to grow at its past year's pace, it too will soon rank among the top50. It was reported that 63% of Tandy's computer revenues were from TRS-80 sales, 26% fromperipherals, 10% from services and 1% from supplies.

Each data processing company in the top 50 reported sales increases, and most were 20% orbetter. For example, IBM's sales rose almost 28%, while Digital Equipment Corporation's sales rosenearly 36%. In fact, none of the traditional maxi or mini makers appear to have been affected bypersonal computers, despite the predictions that were made 2 and 3 years ago.

MAIL: I receive a large number of letters each month, as a result of this column. If you write to meand wish a response, please include a stamped self-addressed envelope.

Sol Libes

ACGNI

1776 Raritan Rd

Scotch Plains NJ 07076

116 September 1979 © BYTE Publications Inc

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BYTE September 1979 117

Inexpensive OpticalPaper-Tape Reader

Brian A Harron

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Ottawa, Ontario

CANADA KIT 1P2

1 microprocessor + 8K BASIC tape+4K Startrek tape +45 min = RUN

This was the terrible equation I hadto contend with every time I wantedto play my favorite game program. Itwould take me 30 minutes to load the8 K BASIC paper tape. But not anymore!

The solution is a 400 character persecond paper-tape reader that can in-terface to any 8-bit input port ofalmost any microprocessor. It usesonly 2 integrated circuits and costsapproximately $15.

I had always wanted somethingfaster than my old reliable Teletype,but I never seemed to have the $40 to$100 that was needed to buy one ofthe many available kits. I alsowondered why most of these kits re-quired so many integrated circuits toaccomplish the simple task of latching8 bits of data. There are 7 bits(sometimes 8 bits) of parallel paper-tape data spaced at regular intervals,and a sprocket hole for strobing, in-cluded at no extra cost. Why notdesign a self-strobing, 8-bit data latchusing an inexpensive large scale in-tegration (LSI) transistor-transistorlogic (TTL) integrated circuit, theINTEL 82127

The Intel 8212 provides 8 bits of in-put, 8 bits of output, strobe, clear,and several device enable lines forabout $5. All I needed to do was tooptically sense the punched paper-tape holes and strobe them into thelatch at every sprocket hole.

Although there are several ready-made, 8-level, paper-tape-readerphotodiode assemblies available, Idecided to construct my own readerassembly using individual photo-transistors that I already possessed,the Motorola type MRD150, whichare available at most wholesalers for

Photo 1: View of the paper-tape readershowing the light source and the light-detecting phototransistors. The springand clamp device keeps the paper tape inplace.

approximately $1 each. Theirminiature size is ideally suited to 0.1inch (0.25 cm) spacing.

Using epoxy, I glued 9 of thephototransistors into a 0.5 by 1 inch(1.27 by 2.54 cm) piece of 0.100 inch(.025 cm) perforated board Thephotocell placed between positions 3and 4 (as shown in figure 1) isphysically reversed so that the activesurface element of the cell is not inline with the other 8 cells. This out-of-line detector provides a physicaldelay of the sprocket-hole signalwhich will be signal-conditionedlater.

This cell begins to detect lightthrough the sprocket hole only afterall other data holes are fully centeredover their respective detectors. Thestrobe pulse is now positioned closeto the center of the pulse from thedata holes, as shown in the wave-forms of figure 2.

In order to make the strobe pulse asinsensitive as possible to the variationin tape speed caused by moving thetape by hand, the sprocket-holedetector is amplified by transistor Qland is threshold-detected by ICla, a7414 hex Schmitt trigger TTL gate(see figure 3, p. 121). The output ofICla is then differentiated and level-shifted by the capacitor and resistorcombination Cl, Rl, and R2 suchthat the output of IClb is fast andclean even for very slow dark-to-lighttransitions through the sprocket hole.

The additional gate sections IClcand ICld provide buffered outputs of

118 September 1979 © BYTE Publications Inc

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BYTE September 1979 119

the signals STROBE and STROBE ,which will be used as sense input linesto the 8-bit interface port.

The last 2 sections of the Schmitttrigger are configured as a delayedpower-up signal that holds theCLEAR input pin of the latch at

ground until the power supplyvoltage has stabilized.

The DS1 and MD pins of the 8212are grounded and the DS2 pin is pin-ned to the supply voltage, thus plac-ing the 8212 into the strobed latchmode of operation. In this way the 8

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<o

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*vj

0

\i

1

f)

i

>

<

>

i

i

1

r

<

>

T

T

ii

T

i>

T

ii

m

m

r)

7

STROBE

n

7

n

7

m

m

rh

Figure 1: Phototransistors in the paper-tape reader. Note the placement of cell betweenbits 3 and 4. The active element is reversed in orientation.

DATA PULSE

STROBE PULSE

STROBE PULSEAFTER CONDITIONING

Figure 2: The strobe pulse is centered in the active signal from the data holes.

UP:

DOWN:

READ:

IN port#

RAL

JNCUP

IN port #

RAL

JC DOWN

IN port#

RETURN

READ INPUT PORT

SHIFT 1 BIT LEFT

JUMP TO UP IF CARRY BIT NOT SET

READ INPUT PORT AGAIN

SHIFT 1 BIT LEFT

JUMP TO DOWN IF CARRY BIT SET

READ INPUT PORT DATA BYTE

WITH 7 BITS OF DATA IN REG A

Listing 1: Simple 8080 assembly language program for inputting the data from thepaper-tape reader.

bits of data available to the input pinsDI-0 thru DI-7 are latched through tothe output pins DO-0 thru DO-7 byeach positive pulse at the STROBEpin.

Since most paper-tape programsused with today's microprocessorsuse only 7 bits of the 8-bit ASCII code(bit 8 being vertical parity), it is con-venient to use this 8th bit as thestrobe sense line. When connectingthe output pins of the latch to the pro-cessor input port, simply select strobesignal STROBE or STROBE and con-nect it to the pin corresponding to bit8.

The software required to read insuch data is shown in listing 1, wherebit 8 is the STROBE sense line. Whenbit 8 goes through a low to high tolow cycle, the data at the input port isvalid.

If 8 bits of tape data are required, itis necessary to connect the strobesense line to either another input portpin or to some other monitor line,such as an interrupt or serial inputline, which can be tested under soft-ware control.

Mechanically, I used a piece of0.100 inch (0.025 cm) aluminum sheetbent into a U-shape, with an inside,bottom width dimension of 1 inch(2.54 cm). I used a small piece of clearPlexiglas as a hold-down device forthe tape as it passed over the readerphotocells. Further improvementscan be added, such as a motor-driven, pinch-roller pull-through, butI have had no problems when pullingthe tape through by hand. As a mat-ter of fact, I can stop pulling at anytime, since the strobe pulse is speedinsensitive. I plan to eventually add ahand crank and a take-up reel toavoid the great piles of tape that endup on the floor after loading some ofmy larger programs.

To generate the required illumina-tion, I used an automotive lamp (type211) mounted 3 inches (7.5 cm) abovethe photocells. Running the lamp on5 V provides a good, uniform sourceof light, although it draws about 1 Aof current.

This entire project took only 3evenings to design and construct, andthe $15 price tag was a bonus. If youare still limited to 10 characters persecond with your Teletype reader,you should seriously consider thishigh-speed paper-tape reader. ■

120 September 1979 © BYTE Publications Inc

+ 5V +5V

i

.IOOK

O^M>^i

IOOK ^'|4

m

+ 5V

AAAAAAAA

\

IOOK(8)

MRDI50^ TYPICAL FOR 8

PHOTOTRANSISTORS

+ 5V

13

14

DS2DI-0

CLEARDO-0

DI-2

DI-3

IC28212

DO-2

DO-3

DI-7 DO-7

DSl MD STROBE

m

\

V.^Sf' 2N3904

[>o^h—^

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IOK

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£>

) TO INPUT PORT OFPROCESSOR

-Obit

-o

-| > BIT 8

-j ^> STROBE

-| ^> STROBE

IC

TYPE

+ 5V

GND

21

82127414

2414

12

7

Figure 3: Schematic diagram of the paper-tape reader, which is capable of 400 characters per second.

September 1979 © BYTE Publications Irtc 121

Bock Reviews

Microcomputer-Based Design

by John B PeatmanMcGraw-Hill Book Co,New York 1977540 pages hardcover$26.95

Microcomputer-Based Design byJohn B Peatman is a combination textand reference book aimed atengineers who wish to learn how todesign systems using microprocessors.It is written not in a dull, dry tone,but rather in a light style. Theminimum required background forthis text is a rudimentary knowledge

of logic (ie: transistor-transistor logicgates and flip-flops) and the basicconcepts of computer programming.The book develops hardware andsoftware design skills upward fromthat point to a practical and usefullevel. A key feature of this book is thelogical, lucid presentation ofarguments present in the manyillustrated design decisions.

Microcomputer-Based Design isdivided into 7 chapters and 6 appen-dices. The chapters are fairly com-plete, in-depth entities and each con-tains a set of practical design pro-blems and additional references. Thereferences may be difficult to find forreaders without access to an engineer-ing library since many of thereferences are articles in engineeringjournals or manufacturers' applica-tion notes.

Chapter 1 is an overview ofmicrocomputer applications focusingprimarily on the distribution of "in-telligence" to instruments and tools.

Chapter 2, "MicrocomputerRegisters and Data Manipulation,"includes a brief discussion of number-ing systems and the various, com-monly encountered modes of address-ing. This is followed by a goodpresentation of machine language in-structions, assembly language, andassembly language programmingtechniques.

Chapter 3 considers computerhardware organization. Several dif-ferent philosophies of commerciallyavailable microprocessor families aredescribed. The characteristics ofvarious logic families are consideredwith an eye towards interconnectioncompatibility. Bus structures andtheir electronic implementation aredescribed in some detail. Flags, inter-rupts, direct memory acess controland programmable timers are alsodescribed with examples.

Chapter 4 reviews the variouscharacteristics of memory com-ponents and systems. Included aresections on the implementation ofmain power failure battery backupsystems and floppy disks.

Chapter 5 examines peripherals.There are sections on input/outputcontrol and handshaking, timing andbuffering. There are also discussionsof specific common microcomputerperipherals: keyboards, photo-transducers, circuit testers, analog-to-digital and digital-to-analog con-verters, pressure transducers, optical

122 September 1979 «-> BYTE Publications Inc

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displays, relay drivers, syn-chromotors and printers. Finally,there are sections on universal asyn-chronous receiver-transmitters(UARTs), line drivers, the HPIB-IEEE488 bus and self-test hardware.

Chapter 6 describes the various op-tions that exist in hardware and soft-ware development packages fromprototyping boards to disk-basedoperating systems. There is also abrief discussion of high-levellanguages for microcomputers.

Chapter 7 describes in detail thealgorithms for solutions to severalcommon microcomputer softwareproblems. Algorithms are describedto read and to parse a functionalkeyboard input, self-test routines andnumber system conversion andmanipulations. Real-time program-ming constraints are also considered.

The set of appendices describes thecharacteristics of specific microcom-puters. Each appendix covers the ar-chitecture and organization of a par-ticular processor integrated circuit.The rest of the integrated circuit set(memory, input/output, etc) is alsobriefly covered. Appendices are in-cluded on the 4004, F8, 8080, 6800,COSMAC, and PPS-8 processors. Itis refreshing to see that these appen-dices are more than just a reprintingof the manufacturer's specificationsheets.

On the negative side, there is adisturbing absence of discussion ofany of the high-performance in-tegrated circuits that were certainlyavailable when this book waswritten. There is also inadequatetreatment given to bit-slice andmicroprogramming techniques. Soft-ware development by emulation isalso omitted. The balance is,however, overwhelmingly positive.This is a text which starts off quietly,never grows dull, and yet contains agreat deal of substance. There are sec-tions on using esoteric devices likefirst in, first out stacks (FIFOs) that Ihave previously never seen in adesign text.

It is a welcome development. Irecommend this book to advancedexperimenters, undergraduateengineering students and practicingengineers. ■

Ira Rampil

2217 Cypress Way

Apt 15

Madison WI 53717

124 September 1979 © BYTE Publications Inc

Circle 349 on inquiry card.

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Programming Quickies

Day of Week andElapsed Time Programs

W B Agocs, Dept of Physical SciencesKutztown State College, Kutztown PA 19530

The day of the week, the number of elapsed days of ayear, and the number of days between 2 dates are infor-mation that is required frequently in various types ofanalyses.

The procedure to determine the day of the week usesZeller's congruence:

[~Y1

C

+

4

4

- -2C}MOD7

d = {[2.6m-0.2] + K + Y +

The term m is the month number minus 2. If the monthis January or February, m is 11 or 12 of the previous year.K is the day of the month; C is the century, and Y is theyear of the century. The value of the square brackets isdefined as the integer part of the result of evaluating theinterior expression.

Day of Week From Date

The program is so written that corrections to month 11or 12 of the previous year are made automatically if themonth is January (1), or February (2). The program isshown in listing 1. Century selection could have been in-corporated, but the program is designed for the 20th cen-tury. Once the number of the day of the week is obtained(with Sunday being day 1), the date and the day areprinted.

Matrix Elapsed Time Determination

The use of a 12 by 31 matrix seems to be the mostlogical method for determining the elapsed days of ayear, the remaining days in a year, and the day intervalbetween 2 dates.

The program for such a determination is shown inlisting 2. The MAT A = CON statement in line 50 setseach element of the matrix equal to 1. The subroutine instatements 440 thru 540 enters 0s into the matrix elementswhich correspond to the months with less than 31 days,and then fills the matrix elements with the date'snumerical location in the year. Thus on return from thesubroutine, the days elapsed may be printed betweenstatements 180 and 190, or between statements 400 and410 if desired. Leap year corrections are made at lines 270and 440.

Finally, if the interval between the 2 dates is less thanor greater than a year (as determined by statement 100),the correct year increment is made in statements 230 and280.

The total time interval is determined in statement 180or 410, and the result printed at statement 190.

Text continued on page 129

126 September 1979 © BYTE Publications Inc Circle 377 on inquiry card.

Bob admits he thought his computerhad reached the limit of its capabilities.Then he discovered the BASIC Compilerfrom Microsoft.

"It's incredibly fast" he boasts. "Nothingwas as fast as my Microsoft BASIC inter-preter—yet this new compiler is actually3-10 times faster.

"And that's not all;' he beamed. "Mycompiler has the same language features asMicrosoft 5.0 BASIC and runs in my 32KCP/M system:'

Bob says, "When Microsoft comes outwith a new product, I know it's got to begood. And this BASIC Compiler is thewizard I've been waiting for.

"At last, I can generate relocatablemachine language modules from myMicrosoft BASIC programs—machinecode that's highly optimized. And becausethe Microsoft macro assembler and loadercome with the BASIC Compiler, BASICprograms are easily linked to assemblylanguage subroutines or Microsoft

FORTRAN and COBOL programs.Just like the pros!' smiled Bob.

"What's more, the compiler generatesa fully symbolic listing of the machinelanguage that's generated—a great way forme to learn assembly code on my own!'

Bob believes in giving credit where creditis due. "Microsoft turned my BASIC com-puter into a genuis for $395, but I wassmait enough to recognize a good thingimmediately'.'

If you want to get the most out of yourcomputer and your BASIC programs, ask formore information on the Microsoft BASICCompiler. We know you'll compliment your-self on a very smart move.

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128 BYTE September 1979

Circle 211 on inquiry card.

Text continued from page 126:

The matrix procedure, with correction for appropriateholidays, can be used in conjunction with stock marketstudies when knowledge of the market day interval isdesired, or when determining if a particular date is amarket trading day.

Listing 1: BASIC program for determining the day of the weekfrom the date using Zeller's congruence.

0010

PRINT "ZELLER'S CONGRUENCE-DAY OF WEEK

FROM DATE."

0020

PRINT "WHAT IS THE DATE-MONTH, DAY, YEAR?"

0030

INPUT M,D,Y

0035

LET Y1 =Y

0037

LETM1 =M

0040

IF(M=1)OR(M = 2)THEN 60

0050

GOTO 105

0060

IF M = 1 THEN 90

0070

LET M = 12

0080

GOTO 100

0090

LET M = 11

0100

LET Y = Y-1

0102

GOTO 110

0105

LET M = M-2

0110

LET D1 =INT(2.6.M-.2) + D + (Y-1900)+INT((Y-1900)/4)

0115

LET D1 =D1 + INT(19/4)-2*19

0120

LET D1 =D1-INT(D1/7).7+ 1

0125

PRINT "D1 =";D1

0130

ON D1 GOTO 140, 150, 160, 170, 180, 190, 200

0140

LET A1$ = "SUNDAY"

0145

GOTO 210

0150

LET A1$ = "MONDAY"

0155

GOTO 210

0160

LET A1$ = "TUESDAY"

0165

GOTO 210

0170

LET A1$ = "WEDNESDAY"

0175

GOTO 210

0180

LETA1$ = "THURSDAY"

0185

GOTO 210

0190

LET A1$ = "FRIDAY"

0195

GOTO 210

0200

LET A1$ = "SATURDAY"

0210

PRINT "FOR ";M1;"/";D;'7";Y1;" IT IS ";A1$

0220

PRINT

0230

END

Listing 2: BASIC program for using a matrix to determine theelapsed time between 2 dates.

0010 PRINT "MATRIX DETERMINATION OF DAYS BETWEEN

DATES."

0020 PRINT "PROGRAMMED APRIL 15, 1979;W. B.

AGOCS."

0030 DIMA(12,31)

0040 DCL S(A())

0050 MAT A = CON

0060 PRINT "WHAT IS THE FIRST MONTH, DATE, YEAR?;

EXPRESS NUMERICALLY AS 11, 15, 1978."

0070 INPUT M1, D1, Y1

0080 PRINT "WHAT IS THE NEXT MONTH, DATE, YEAR?"

0090 INPUT M2, D2, Y2

0100 IF Y2-Y1 =0THEN 120

0110 GOTO 220

0120 IF Y1/4-INT(Y1/4) = 0THEN 150

0130 GOSUB450

0140 GOTO 160

0150 GOSUB440

0160 LETS1 =A(M1, D1)

0170 LET S2 = A(M2, D2)

0180 LETS3 = S2-S1

0190 PRINT "INTERVAL BETWEEN ";M1;"/";D1;"/";Y1;

0195 PRINT " AND ";M2;"/";D2;,7";Y2;" IS ";

0200 PRINT S3;" DAYS."

0210 GOTO 580

0220 LET S = 0

0230 FOR l = Y1+ 1 TO Y2-1 STEP 1

0240 IF l/4-INT(l/4) = 0 THEN 270

0250 LETS = S + 365

0260 GOTO 280

0270

LETS = S + 366

0280

NEXT I

0290

IF Y1/4-INT(Y1/4) = 0 THEN 320

0300

GOSUB 450

0310

GOTO 350

0320

GOSUB 440

0330

LETS1 =366-A(M1,D1)

0340

GOTO 360

0350

LETS1 =365-A(M1,D1)

0360

IF Y2/4-INT(Y2/4) = 0 THEN 390

0370

GOSUB 450

0380

GOTO 400

0390

GOSUB 440

0400

LETS2 = A(M2,D2)

0410

LETS3 = S + S1 +S2

0420

GOTO 190

0430

REM SUB-ROUTINE

0440

LET A(2,29) = 0

0450

LET A(2,30) = A(2,31) = A(4,31) = A(6,31) == A(11, 31) = 0

= A(9,31)

0460

LET N = 0

0470

FOR 1 = 1 TO 12 STEP 1

0480

FOR J = 1 TO 31 STEP 1

0490

IF A(I,J) = 1 THEN 510

0500

GOTO 530

0510

LET N = N + 1

0520

LETA(I,J) = N

0530

NEXT J

0540

NEXT I

0550

RETURN

0560

PRINT

0570

PRINT

0580

PRINT "THE END."

0590

END ■

A Text LoaderRoutine

Howard Berenbon

2681 Peterboro

W Bloomfield MI 48033

Here is a useful program for the Motorola 6800microcomputer. This subroutine allows the loading ofASCII text into the desired memory location directlyfrom your terminal. It uses the Motorola MIKBUGmonitor for character input and output. The subroutinemay be entered beginning at hexadecimal address A060.To exit the program simply type a %.

Hexadecimal Hexadecimal

Address

Code

Mnemonic

Comments

A060

86

3F

LDAA #$ 3F

Load A with ?

A062

BD

EO

75

JSR CHAROUT

Output ?

A065

86

20

LDAA #$ 20

Load A with a space

A067

BD

EO

75

JSR CHAROUT

Output space

A06A

CE

-

-

LDX #$

Load index register withdesired address

A06D

BD EO&LOOP

78

JSR CHARIN

Input character

A070

A7

00

STAA $ 00:X

Store A indexed

A072

08

INX

Increment index register

A073

81

25

CMPA #$ 25

Compare A with %

A075

26

F6

BNE &LOOP

Get another character

A077

7E

E0E3

JMP MIKBUG

Return to MIKBUG ■

September 1979 © BYTE Publications Inc 129

A Model of the Brainfor Robot Control

Part 4: Mechanisms of Choice

The essence of a hierarchy is thatcontrol is top-down. The ultimatechoices are made at the top, and thegoals selected at this level are decom-posed into action as they filter down

The ideas presented in this article repre-sent the views of the author and not thoseof the Department of Commerce or theNational Bureau of Standards.

James Albus

Project Manager

National Bureau of Standards

United States Dept of Commerce

Washington DC 20234

through the various levels of thehierarchy. For the purposes of ourdiscussion, we will define the highestlevel H function in the behavior-generating hierarchy of the humanbrain as the will.

For centuries philosophers andtheologians have debated the natureof the will, particularly the questionof whether humans have "free" will(ie: the freedom to choose goals) or

whether all choice is merely a reflex-ive or predestined response to the en-vironment. We shall not presume todeal with this question here, otherthan to suggest what types of inputsare available to this highest level goalselection module.

By definition much of the input tothe highest level behavior-generatingmodule must come from the highestlevel sensory-processing module.

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Figure 1: An action (such as a person talking to a flower) may be recognized as either familiar or unfamiliar. If an action is noted asfamiliar, then it can be considered unnoteworthy and will be ignored. If the action is considered deviant, further processing will takeplace to determine reactions to the action.

130 September 1979 © BYTE Publications Inc

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This is the level at which the overallresult of the entire sensory processingoperation is evaluated as being goodor bad, rewarding or punishing, satis-fying or frustrating. In humans, thisfunction is performed by what arecommonly called the emotions. It haslong been recognized that emotionsplay a crucial role in the selection of

About the Author

Dr ]ames S Albus worked for NASA from1957 to 1972 designing optical and electronicsubsystems for over 15 spacecraft, and for oneyear managed the NASA Artificial IntelligenceProgram. Since 1973 he has been with theNational Bureau of Standards where he hasreceived several awards for his work inadvanced computer control systems for in-dustrial robots. He has written a survey articleon robot systems for Scientific American(February 1976) and his Cerebellar ModelArithmetic Computer won the IndustrialResearch Magazine IR-100 Award as one of the100 most significant new products of 1975. Heis also the author of People's Capitalism: TheEconomics of the Robot Revolution which ispublished by New World Books, 4515 Saul Rd,Kensington MD 20795.

behavior. We tend to practice thatwhich makes us feel comfortable andavoid what we dislike. Our behavior-generating hierarchy normally seeksto prolong, intensify, or repeat thosebehaviors which give us pleasure ormake us feel happy or contented. Wenormally seek to terminate, diminish,or avoid those behavior patternswhich cause us pain, or arouse fear ordisgust.

In the past 25 years it has becomeknown that the emotions aregenerated in localized areas, or com-puting centers, in the brain. For ex-ample, the posterior hypothalamusproduces fear, the amygdala gen-erates anger and rage, the insula com-putes feelings of contentment, and theseptal regions produce joy and ela-tion. The perifornical nucleus of thehypothalamus produces punishingpain, the septum pleasure, theanterior hypothalamus sexualarousal, and the pituitary computesthe body's response to danger andstress. These emotional centers, along

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with many others, make up a com-plex of about 53 regions linkedtogether by 35 major nerve bundles.This entire network is called the lim-bic system. Additional functions per-formed in the limbic system are theregulation of hunger and thirst per-formed by the medial and lateralhypothalamus, the control of bodyrhythms such as sleep-awake cyclesperformed by the pineal gland, andthe production of signals which con-solidate (ie: make permanent) thestorage of sensory experiences inmemory performed by the hippo-campus. This last function allows thebrain to be selective in its use ofmemory by facilitating the permanentstorage of sensory experiences towhich the emotional evaluatorsattach particular significance (eg:close brushes with death, punishingexperiences, etc).

Input to the limbic system emo-tional centers consists of highly pro-cessed sensory-data such as the namesof recognized objects, events, rela-tionships, and situations, such as therecognition of success in goal achieve-ment, the perception of praise orhostility, or the recognition ofgestures of dominance or submissiontransmitted by social peers. These in-puts are accompanied by such modi-fier variables as confidence factorsderived from the degree of correlationbetween predicted and observed sen-sory input.

Sensory processing at the level ofthe emotions is heavily influenced bycontextual information derived frominternal models and expectations atmany different levels in the proces-sing hierarchy. If a painful stimulus isperceived as being associated with anonfear producing source, we mayattack the pain causing agent. If,however, the perceived source of painalso induces fear, we may flee.

Similarly if an observed event suchas a person talking to a flower is per-ceived as deviant, then this input tothe emotions, along with otherrecognized qualifier variables such asthe person is a) eccentric, b) retarded,or c) dangerously psychotic, willcause the emotions to output a)amusement, b) pity, or c) fear,respectively. Amusement input to thebehavioral goal selecting module maylead to laughter, poking fun, orridicule. Pity input to the will may

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evoke a behavioral pattern of sym-pathy. Fear may evoke an attempt tosecure medical or psychiatric treat-ment, or incarceration.

If, however, a person talking to aflower is recognized as perfectly nor-mal, then the emotions will give noindication that the event is particu-larly worthy of attention, or thatthere exists any need to deviate fromwhatever behavior is presently beingexecuted. These relationships aredescribed graphically and symboli-cally in figure 1.

In this model the standards of nor-malcy and deviance are clearly in theeye of the beholder, or at least in theexpectations and beliefs stored in theprocessing-generating hierarchy. Inmany ways the emotional evaluatorsare even more dependent on internalbeliefs than externally observed facts.This is particularly true in the casewhere a person's belief structure dis-counts the reliability or moral worthof the physical senses, as ischaracteristic of philosophical con-structs derived from gnosticism orasceticism.

Thus the emotions, just as anyother sensory processing module in

the brain, simply compute a G func-tion on the D vector that they inputto produce the Q vector that theyoutput. In simple creatures the emo-tional output vector may be restrictedto a few components such as good-bad, pleasure-pain, etc. In higherforms the emotional output is ahighly multidimensional vector withmany faceted components such aslove, hate, jealousy, guilt, pride,disgust, etc. Part of this Q outputmay simply produce feelings (ie: joy,sadness, excitement, fear, etc).However, most of the Q outputdirectly or indirectly provides F inputto the highest level H function, thewill.

Output from the emotional centersis known to be of two types: one con-sists of signals on nerve fibers; theother consists of hormones andchemical transmitters which conveytheir messages (Q vector values) viafluid transport mechanisms.

What the G and H functions of theemotions and will are, and wherethey come from is a matter of hotdispute. One recent theory proposedby sociobiology is that they are gene-tically determined, derived from in-

formation stored in the DNAmolecule, as the result of millions ofyears of natural selection. This theoryargues that innate behavior-selectingmechanisms have evolved so as tomaximize the Darwinian fitness (theexpected number of surviving off-spring) of their possessors.

The incidence of behavior in manydifferent species from insects to birdsto mammals corresponds closely tomathematical predictions derivedfrom genetics and game-theoryanalyses of strategies for maximizingthe probability of gene propagation.Even cooperative or altruisticbehavior such as that of the workerbee, and ritualized behavior in animalcontests and courtship, can in manycases be explained by geneticarguments. However, the evidencefor this theory is much stronger forinsects than for higher forms, and theopinion that human emotions aretransmitted genetically is not widelyheld.

A competing theory put forwardby behaviorists is that in higher formsthe evaluator functions of the emo-tion and the selector functions of thewill are mostly learned, perhaps even

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imprinted, during the early years ofdevelopment. Certainly many of theemotional evaluations and behaviorselection rules in the human brain areculturally determined, derived fromreligious teachings defining good andevil, or from social conventionsdefining duty, fairness, etiquette, andlegality. These fundamental rules ofopinion and behavior are instilled inthe young by parents, educators, andreligious and state authorities. Theyare reinforced throughout life by peergroup pressure, as well as by churchand civil sanctions.

There are, of course, many personswho would disagree with both ofthese theories. Perhaps the mostwidespread opinion (which untilrecent years was virtually unchal-lenged) is that the human will and itsemotional evaluator inputs are non-mechanistic in nature and thereforeunknowable in some fundamentalsense. Many would even claim thatemotions and will are subject to, orcontrolled by, spiritual and super-natural forces. For example, the doc-trine of original sin states that thehighest level behavior selectingmechanism, the human will, is

basically defective because of thedisobedience of Adam and Eve, andexcept for divine intervention isunder the power of evil or satanicforces. The literature surrounding theage old controversy over free willversus predestination centers largelyon the role of the Divinity (or thestars, or fates) in the determination ofhuman behavior. Most cultures viewthe conscience (ie: the emotionalevaluator for right and wrong orgood and evil) as a divine gift ormanifestation of the indwelling of thespirit of God.

Clearly the emotions and will are avery basic (some would say prim-itive) and compelling part of ourbehavioral mechanism. Carl Sagancalls them the Dragons of Eden.Humans are often driven, sometimesbeyond rational justification, toheroic feats of courage or physicalendurance by the behavior rules ofduty or the emotions of love, pride,guilt, jealousy, and hate.

Whatever their origins, the G func-tions of our emotions and the H func-tions of the will can be modeled.They are rule based, and the rulesare, for the most part, clearly defin-

ed. In many cases these rules are evenwritten down as systems of moralphilosophy, ethics, or rules of socialbehavior such as Emily Post's Book ofEtiquette.

Nothing so complex need bemodeled for the highest level G and Hmodules of a robot for many years.Nevertheless, every robot needs somesort of highest level evaluator andgoal selector function in order to ex-hibit any sort of autonomous be-havior. At what point in the spectrumof multidimensional sophisticationwe choose to dignify an evaluatorfunction with the term emotion, orgoal selection function with the termwill, is not clear. What is clear is thatsimple approximations to the func-tions computed by the emotions andthe will can be moduled by CMAC Gand H functions operating on inputvectors and computing output vec-tors. The degree of sophistication andcomplexity of the modeling is limitedonly by the ingenuity and resourcesof the modeler.

The interdependency of the pro-cessing and generating hierarchiessuggests at least 3 distinct modes ofoperation.

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Acting—The Task ExecutionMode

In the task execution mode themotor-generating hierarchy is com-mitted to a goal, which it decomposesinto subgoals, sub-subgoals, andfinally into action primitives. In thismode the sensory-processing hier-archy is primarily engaged in pro-viding feedback; first to aid in se-lecting the goal, then to steer the goaldecomposition process, and finally todirect the output drive signals to themuscles (or actuators) so as to followa success trajectory.

Consider a simple, everyday goalsuch as the fixing of a leaking faucet.First, the sensory processing systemmust recognize the fact that the faucetis leaking. This information is thenevaluated by the emotions as some-thing that needs attention. Thisevaluation is passed on to the will,where the rules of what ought to bedone and under what circumstancesreside. If there are no higher priorityitems vying for the attention of thewill, then the goal <fix faucet> maybe selected. Once this occurs, thebehavior generating hierarchy will becommitted to decompose this goalinto a sequence of actions.

At each instant of time tk thesensory-processing module at eachhierarchical level extracts feedbackvectors F* required by the Hbehavior-generating modules at eachlevel for goal decomposition. At theinstant t0 when the goal is selected,the feedback F? at the various levelscauses the selection of the initialsubgoal decompositon P°. This deter-mines the initial direction of the tra-jectories TP,. on their way toward thegoal state. As the task proceeds, therecognition of subgoal completionsand/or unanticipated obstacles trig-gers the selection of the proper se-quence of actions directed toward thegoal achievement.

The entire set of trajectoriesT ^describes the sequence of internalstates of the brain which underlie andgive rise to the observable phen-omena of purposive behavior. Theseare the deep structure of behavior.Only the output trajectory, the ter-minal or bottom level trajectory, ismanifested as overt action. The ex-tent to which the trajectories TP]. areindependent of feedback is the extentto which behavior is preprogrammed.The extent to which the feedbackpulls the TP. trajectories along predic-

table paths to the goal state is the ex-tent to which behavior is adaptive.For some goals, such as hunting forprey or searching for breeding ter-ritory, the selection of the goalmerely triggers migratory searchingbehavior which continues until feed-back indicates that the goal is near athand. For such goals, behavior is in-definite and highly feedback depen-dent. For other goals, such asbuilding a nest, making a tool,courting a mate, or defending aterritory, behavior is more inner-directed, requiring only a few sensorycues for triggers.

In either case, while in the actingmode the sensory data flowing in thesensory-processing hierarchy ishighly dependent on (if not directlycaused by) the action itself. If theaction is speech, the sensory-processing hierarchy is analysingwhat is spoken, and provides feed-back for control of loudness, pitch,and modulation. If the action isphysical motion, data from vision,proprioception, and touch sensors areall highly action dependent, and thesensory analysis is primarily directedtoward servo control of the actionitself.

In the action mode, the M,-associative memory modules providecontext in the form of predicted datato the sensory-processing modules inorder to distinguish between sensorydata caused by motion of the sensorsand that caused by motion of the en-vironment. What is predicted iswhatever was stored on previous ex-periences when the same action wasgenerated under similar circum-stances. This allows the sensory-processing hierarchy to anticipate thesensory input and to detect moresophisticated patterns in the sensorydata than would otherwise be possi-ble.

Observing—The SensoryAnalysis Mode

A second mode of operation of thecrosscoupled hierarchy is the analysisof sensory data from external sourcesnot primarily caused by action of thebehavior-generating hierarchy. Forexample, when listening to a concert,a speech, or a play, there is little ac-tion going on in the muscles andmotor neurons. The lower levels ofbehavior-generating hierarchies arequiescent, or set to a constant value,or given a command to execute an

138 September 1979 © BYTE Publications Inc

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BYTE September 1979 139

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overlearned task which can be carriedout without any assistance from theupper levels.

The sensory-processing hierar-chies, however, are very busy. Theyare filtering and predicting, recogniz-ing patterns and trajectories, lockingon to rhythms and harmoniousperiodicities, and tracking targets ofattention. Predictions generated bythe M modules are clearly requiredfor these types of analyses, whetheror not the organism is engaged inphysical activity. This suggests thatthe upper levels of the behavior-generating hierarchies (which are notcurrently required for generatingbehavior) might be used instead togenerate hypotheses and subhypo-theses which in turn produce contextand predictions to aid the sensory-processing hierarchy in the recogni-tion, analysis, and understanding ofincoming sensory data.

At each level hypotheses whichgenerate TK predictions that match ortrack the TE sensory data trajectorieswill be confirmed. If the hypothesizedTK trajectories are only close to the TEobservations, they can be pulled byerror signal feedback TV from the pro-cessing hierarchies. When a hypo-thesis is successful in generatingpredictions which match the sensorydata stream, the loop at that levellocks onto the sensory data. Whenlock-on is simultaneously achieved atmany different levels, we can say thatthe processing-generating hierarchy"understands" the incoming data (ie:it can follow and predict it at manydifferent levels). The depth ofunderstanding depends upon howmany levels lock onto the sensorydata stream. The accuracy ofunderstanding depends upon howprecisely the hypotheses track andpredict the incoming sensory data.

It is easier to follow a trajectorythan to reproduce it. When observinga procedure, the generating hierarchymerely needs to produce hypotheseswhich are in the right vicinity so thatthey can be synchronized with thesensory input. Uncertainties atbranch points in TP, do not mattergreatly because errors are quicklycorrected by comparing Tfi. with T£l..

On the other hand, reproducing aprocedure requires that the H func-tions be capable of generating TPl tra-jectories which are quite precise overtheir entire length. They must notwander outside of the success

envelope or miss any critical branchpoints. Needless to say, the latter is amuch more exacting computationalproblem, and offers an explanationfor why a student may be able tofollow the reasoning of his professor'slecture, but is unable to pass an examwithout additional drill and practice.

Attention

The directing or focusing of atten-tion is essentially a purposive actionwhose goal is to optimize the qualityof the sensory data. The basicelements of attention are orienting(positioning the body and sensoryorgans so as to facilitate the gatheringof data) and focusing (blocking outextraneous or peripheral informationso that the sensory processing systemcan bring all of its capacities to bearon data that is relevant to the objectof attention). The orienting element issimply a behavioral task or goal toacquire and track a target. The fo-cusing element is a filtering problemwhich can be solved by a hypothesisor goal decomposition which evokesthe appropriate masks or filter func-tions from the R, modules so as toblock out all but the relevant sensoryinput data.

Thus, attending is a combination ofobserving and acting. It is primarily asensory analysis mode activity, witha stong assist from the task executionmode.

Imagining—The Free-Running Mode

A third distinct mode of operationoccurs when the upper levels of theprocessing-generating hierarchy arelargely disconnected from both motoroutput and sensory input. In thismode high-level hypotheses TP. maybe generated, and predicted sensorydata Tfi| recalled. In the absence ofsensory input from the external en-vironment, these recalled trajectoriesmake up all of the information flow-ing in the sensory-processing hier-archy. The processing modules G,operate exclusively on the internallyrecalled R, trajectories producingTQ,experiences and TFi feedback. The^trajectories act on the generatinghierarchy so as to modify and steerthe Xs, trajectories creating newhypotheses TP,.. The system is freerunning, guided only by stored ex-periences M,, learned interpretationsG„ and practiced skills H„ for

140

September 1979 © BYTE Publications Inc

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BYTE September 1979 141

generating strings of hypotheses anddecomposing goals and tasks. Theupper levels of the crosscoupledhierarchy are, thus, imagining (ie:generating and analyzing what wouldbe expected if certain hypothesizedgoals and tasks were to be carriedout).

Imagination is based on stored ex-periences and driven by hypothesizedactions. It is constrained in largemeasure by the knowledge frames,world models, expected values, andbelief structures (IF I do this, THENsuch and so will happen) embedded inthe upper levels of the cross-coupled

processing-generating hierarchy.

If we attempt to hypothesize someaction X which lies outside of theneighborhood of generalization ofprior experience, we get no recalled R,vectors from memory M,. In this casewe say "we cannot imagine what Xwould be like."

One of the functions of the free-running mode is to remember orrecall past experiences by hypothesiz-ing the same goals as when the ex-perience was recorded. Thus, in ourimagination we can reach back andrelive experiences, recall events, and,hence, remember facts and relation-

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ships from our past. Imagination,however, is not limited to duplicationof past experiences. We can also re-arrange sections of learned trajec-tories to create experiences in ourminds which never occurred. We canstring together trajectories in newcombinations or insert new modifiervariables in various hypothesis vec-tors. We can watch a bird fly andsubstitute a "self" variable in place ofthe bird to imagine ourselves soaringthrough the sky. We can listen to astory of adventure and imagineourselves in the place of one of thecharacters. Imagination allows us tohypothesize untried actions and, onthe basis of M functions learnedduring previous experiences, topredict the outcome.

Planning

Imagination gives us the ability tothink about what we are going to dobefore committing ourselves to ac-tion. We can try out, or hypothesizeprospective behavior patterns, andpredict the probable results. Theemotions enable us to evaluate thesepredicted results as good or bad,desirable or undesirable.

Imagination and emotional evalu-ators together give us the capabilityto conduct a search over a space ofpotential goal decompositions and tofind the best course of action. Thistype of search is called planning.

When we plan, we hypothesizevarious alternative behavior trajec-tories and attempt to select the onethat takes us from our present state tothe goal state by the most desirableroute. Imagined scenarios which pro-duce positive emotional outputs areflagged as candidate plans. Favorablyevaluated scenarios or plans can berepeatedly rehearsed, reevaluated,and refined prior to initiation ofbehavior-producing action.

Imagined scenarios which producenegative evaluation outputs will beavoided if possible. In some situa-tions it may not be possible to find apath from our present state to a goalstate, or at least not one which pro-duces a net positive evaluation.Repeated unsuccessful attempts tofind a satisfactory, nonpunishingplan, particularly in situationsrecognized as critical to one's well-being, correspond to worry.

One of the central issues in thestudy of planning is the searchstrategy, or procedure, which dictates

142 September 1979 © BYTE Publications Inc

Circle 47 on inquiry card.

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BYTE September 1979 143

which of the many possible hypo-theses should be evaluated first. Inmost cases, the search space is muchtoo large to permit an exhaustivesearch of all possible plans, or evenany substantial fraction of them. Theset of rules for deciding whichhypotheses to evaluate, and in whichorder, are called heuristics.

Heuristics are usually derived in anad hoc way from experience, acci-dent, analogy, or guesswork. Oncediscovered, they may be passed fromone individual to another, and fromone generation to another byteaching.

Historically, artificial intelligenceresearchers have been fascinated bythe subject of heuristics. At least aportion of this interest is a result oftheir recursive nature. A heuristic is aprocedure for finding a procedure.When this recursion is embedded in across-coupled processing-generatinghierarchy with the rich complexity ofthe human brain, it becomes clearwhy the thoughts and plans ofhumans are filled with such exquisitesubtleties, and curious, sometimes in-sidious reasoning. It also providessome insight into the remarkablephenomenon of self-consciousness

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(ie: a computing structure with thecapacity to observe, take note of,analyze, and, to some extent, evenunderstand itself.)

Much of the artificial intelligenceresearch in planning and problemsolving has its origins and theoreticalframework based on simple boardgames where there are a finite(although sometimes very large)number of possible moves. Thediscrete character of such games,together with the digital nature ofcomputers, led naturally to theanalysis of discrete trees, graphs, andsearch strategies for such structures.

Planning in a natural environmentis much more complex than searchingdiscrete trees and graphs. In the studyof planning in the brain it is necessaryto deal with the continuous time-dependent nature of real worldvariables and situations. States arenot accurately represented as nodes ina graph or tree; they are more likepoints in a tensor field. Transitionsbetween states are not lines or edges,but multidimensional trajectories(fuzzy and noisy at that). In a naturalenvironment, the space of possiblebehaviors is infinite. It is clearly im-possible to exhaustively search anysignificant portion of it. Furthermore,the real world is much too unpredic-table and hostile, and wrong guessesare far too dangerous to make ex-ploration practical outside of a fewregions in which behavior patternshave had a historical record of suc-cess. Thus behavior, and hence im-agination and planning, is confined toa relatively small range of possi-bilities, namely those behavior andthought patterns which have beendiscovered to be successful throughhistorical accident or painful trial anderror. Both the potential behaviorpatterns and the heuristics for selec-ting them are passed from one genera-tion to another by parents, educators,and civil and religious customs.

Daydreaming or Fantasizing

The fact that the imagination cangenerate hypothetical scenarios withpleasurable emotional evaluationsmakes it inevitable that suchscenarios will, upon occasion, berehearsed for their pleasure-pro-ducing effect alone. This is a pro-cedure that can only be described asdaydreaming or fantasizing.

When we daydream we allow ourhypothesis generators to drift

144 September 1979 © BYTE Publications Inc

Circle 13 on inquiry card.

S reasons why you should not buy

the electric pencil II

^* ° 1978 Michael Shrayer

Check the appropriate box(es):

You love typing the same copy 20 thousand times a day.

□ Your secretary can type 250 words per minute.

□ You're dying to spend $15,000 on a word processing system, just for thetax investment credit.

□ All your capital assets are tied up in a 10-year supply of correction fluid.

□ You never commit a single thought to paper.

If you have checked one or more boxes, you do not need The Electric Pencil.On the other hand, you may want to join the thousands of people who haven'tchecked a single box.

TM

The Electric Pencil II is a Charac-ter Oriented Word Processing System.This means that text is entered as astring of continuous characters and ismanipulated as such. This allows theuser enormous freedom and ease in themovement and handling of text. Sinceline endings are never delineated, anynumber of characters, words, lines orparagraphs may be inserted or deletedanywhere in the text. The entirety ofthe text shifts and opens up or closesas needed in full view of the user. Thetyping of carriage returns or wordhyphenations is not required sincelines of text are formatted automatic-ally.

As text is typed and the end of aline is reached, a partially completedword is shifted to the beginning of thefollowing line. Whenever text is insert-ed or deleted, existing text is pusheddown or pulled up in a wrap aroundfashion. Everything appears on thevideo display as it occurs, which elim-inates guesswork. Text may be review-ed at will by variable speed scrollingboth in the forward and reverse direc-tions. By using the search or searchand replace functions, any string ofcharacters may be located and/or re-placed with any other string of charac-ters as desired.

Numerous combinations ofline length, page length, linespacing and page spacing permitautomatic formatting of anyform. Character spacing, boldface, multicolumn and bidirec-tional printing are included inthe Diablo versions. Multiplecolumns with right and left justifiedmargins may be printed in a single pass.

Wide screen video

Versions are available for ImsaiVIO video users with the huge 80x24character screen. These versions put al-most twice as many characters on the

CP/M versions

Digital Research's CP/M, as well asits derivatives, including IMDOS andCDOS, and Helios PTDOS versions arealso available. There are several NECSpinwriter print packages. A utilityprogram that converts The ElectricPencil to CP/M to Pencil files, calledCONVERT, is only $35.

Features

• CP/M, \MDOSand HELIOS compatible

• Supports four disk drives

• Dynamic print formatting

• DIABLO and NEC printer packages

• Multi-column formatting in one pass

• Print value chaining

• Page-at-a-time scrolling

• Bidirectional multispeed scrolling con-trols

• Subsystem with print value scoreboard

• Automatic word and record numbertally

• Cassette backup for additional storage

• Full margin control

• End-of-page control

• Non-printing text commenting

• Line and paragraph indentation

• Centering

• Underlining

• Bold face

Upgrading policy

Any version of The Electric Pencil

Have we got a versionfor you?

The Electric Pencil II operateswith any 8080/Z80 based microcom-puter that supports a CP/M disk sys-tem and uses an Imsai VIO, ProcessorTech. VDM-1, Polymorphic. VTI, SolidState Music VB-1B or Vector Graphicvideo interface. REX versions alsoavailable. Specify when using CP/Mthat has been modified for Micropolisor North Star disk systems as follows:for North star add suffix A to versionnumber; for Micropolis add suffix B,e.g.,SS-IIA, DV-IIB.

Vers.

Video

Printer

Price

SS-II

SOL

TTY or similar

$225

SP-ll

VTI

TTY or similar

225

SV-II

VDM

TTY or similar

225

SR-II

REX

TTY or similar

250

Sl-ll

VIO

TTY or similar

250

DS-II

SOL

Diablo 1610/20

275

DP-II

VTI

Diablo 1610/20

275

DV-II

VDM

Diablo 1610/20

275

DR-II

REX

Diablo 1610/20

300

Dl-ll

VIO

Diablo 1610/20

300

NS-II

SOL

NEC Spinwriter

275

NP--II

VTI

NEC Spinwriter

275

NV-II

VDM

NEC Spinwriter

275

NR-II

REX

NEC Spinwriter

300

Nl II

VIO

NEC Spinwriter

300

SSH

SOL

Helios/TTY

250

DSH

SOL

Helios/Diablo

300

MICHAEL SHRAYER SOFTWARE, INC

1253 Vista Superba Drive

Glendale, CA. 91205

(213)956-1593

may be upgraded at any time by sim-ply returning the original disk or cas-sette and the price difference betweenversions, plus $15 to Michael ShrayerSoftware. Only the originally purchas-ed cassette or diskette will be acceptedfor upgrading under this policy.

Attention: TRS-80 Users!

The Electric Pencil has been de-signed to work with both Level I(16K system) and Level II mod-els of the TRS-80, and with vir-tually any printer you choose.Two versions, one for use withcassette, and one for use withdisk, are available on cassette.The TRS-80 disk version is easily tran-sferred to disk and is fully interactivewith the READ, WRITE, DIR, andKILL routines of TRSDOS 2.1.Version Storage Price

TRC Cassette $100.TRD Disk $150.

ill!

Demand a demo from your dealer!

Circle 319 on inquiry card.

BYTE September 1979 145

Circle 77 on inquiry card.

PET PRINTER ADAPTER

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wherever our emotional evaluatorspull them. Our imagination gravi-tates toward those trajectories whichare emotionally most rewarding.Some of the most pleasurablescenarios we can imagine arephysically impossible, impractical, orsocially taboo. Most of us recognizethese as fantasies and never attemptto carry them out. However, once aperson adopts the intent to carry outa fantasy, it ceases to be a dream andbecomes a plan.

Thus, planning and daydreamingare closely related activities, differingprincipally in that planning has aserious purpose and involves an in-tent to execute what is finally selectedas the most desirable of the alter-native hypotheses.

This model suggests that dreamingwhile sleeping is similar in manyrespects to daydreaming. The prin-cipal difference in night dreamingseems to be that the trajectoriesevoked are more spasmodic and ran-dom, and are not always under thecomplete control of the emotions andwill.

Creativity

The notion of planning or dis-covering procedures for achievinggoals leads inevitably to the issue ofcreativity. If we assume that most ofthe H, G, and M functions in theprocessing-generating hierarchy arelearned, then where is the creativity?Is creativity merely an illusiongenerated by the recursion of pro-cedures for discovering procedures?

Certainly we as humans like tothink of ourselves as creative. Butwhat are we doing when we createsomething new? Typically we borrowan idea from here, put it togetherwith another from there, and give it adifferent name. We take a familiarbehavioral trajectory, add a tinyvariation, and claim that we havediscovered something completely new— a new dance step, dress style,song, or idea. Seldom, however, areany of these more than the slightestdeviation from a preexisting pro-cedure or behavioral trajectory. Toquote Ecclesiastes: "There is nothingnew under the sun."

True creativity, in the sense of the

invention of an entirely new behav-ioral trajectory, is extremely rare, if itever occurs at all. Furthermore, it ishighly doubtful that a truly creativeact would be recognized if it ever didoccur. Our processing-generatinghierarchies cannot lock on to sensoryinput patterns which are totally dif-ferent from everything that is storedin them. We reject such inputs asmeaningless noise, or as alien andpossibly hostile. True creativitywould be as incomprehensible as abook written in a foreign language, ora theorem expressed in an unknownmathematical notation.

In one sense we are all creative ineverything that we do, since no twobehavioral trajectories are everrepeated exactly. However, the day-to-day variations in our ordinarybehavior are not what we usuallymean when we speak of creativity.We take pride in those moments of in-spiration when something clicks, andwe produce a great invention or awork of art.

Nonetheless, if we analyze a list ofthe great creative ideas which have

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shaped human history, we find thateven these have been little more thanclever rearrangements of well-knownpreexisting patterns or procedures.

Consider the fact that it took thehuman race many millenia to learn tostart a fire, to grow a crop, to build awheel, to write a story, to ride ahorse. Even the Greeks did not knowhow to build an arch. Yet these are allsimple procedures which any childcan understand and more or lessmaster. Surely our ancestors as adultswere as intelligent and creative as to-day's children. Why did they fail forhundreds of years to discover thesesimple yet highly useful procedures?

It was because they had no one toteach them. A modern child knowsabout wheels because he is taught. Heplays with toys that have wheels. Herides in vehicles with wheels. If amodern child grew up in a culturewhere he never saw a wheel, hewould never think of one, nor wouldhis children, or his grandchildren,any more than his ancestors did forthousands of years before him.

The reason that we value creativity

so highly is because it is so rare and sohighly advantageous. Once a newand useful procedure like navigatinga ship, making steel, or flying anairplane is discovered, it can easily betaught to others. Entirely new worldsof possible behavior patterns open upfor all who possess the secret.

We learn to solve problems, to in-vent, and to be creative, in much thesame way as we learn any other goal-directed behavior pattern such ashunting, dancing, speaking, orbehaving in a manner that is accep-table to and approved by our peers.We learn it from a teacher. Thebeauty, the sense of awe and wonderwe experience when confronted by awork of creative genius, derives notso much from its novelty/creativityas from the skill and precision withwhich it is executed.

Implications for Robot Design

There is little need to worry aboutprogramming "creativity" into ourmachines. If we design systems withsufficient skill in executing tasks andseeking goals, and sufficient sophis-

tication in sensory analysis and con-text sensitive recall, and if we teachthese systems procedures for selectingbehavior patterns which are appro-priate to the situation, then they willappear to be both intelligent andcreative. But there will never be anyparticular part of such a device towhich one can point and say "Here isthe intelligence," or "Here is thecreativity." Skills and knowledge willbe distributed as functional operatorsthroughout the entire hierarchy. Tothe degree that we are successful, in-telligence and creativity will beevidenced in the procedures whichare generated by such systems.

Above all, we should not expectour robots to be more clever thanourselves, at least not for manydecades. In particular we should notexpect our machines to programthemselves, or to discover forthemselves how to do what we do notknow how to teach them. We teachour children for years. It will take atleast as much effort to teach ourmachines.

We must show our robots what

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each task is and how to do it. Wemust lead them through in explicitdetail, and teach them the correctresponse for almost every situation.This is how industrial robots are pro-grammed today at the very lowest,levels, and this is, for the most part,how children are taught in school. Itis the way that most of us learnedeverything we know, and there is noreason to suspect that robots will beprogrammed very differently. Surelyit is as unreasonable to expect a robotto program itself as it is to expect achild to educate himself. We shouldnot expect our robots to discover newsolutions to unsolved problems or todo anything that we, in all thethousands of generations we havebeen on this earth, have not learnedhow to do ourselves.

This does not mean that once wehave trained our robots to a certainlevel of competence that they can'tlearn many things on their own. Wecan certainly write programs to takethe routine and the tedium out ofteaching robots. Many differentlaboratories are developing high-levelrobot programming languages. Wealready know something about howto represent knowledge in computersabout mathematics, physics, chem-istry, geology, and even medicaldiagnosis. We know how to programcomplex control systems and tomodel complicated processes, and weare rapidly learning how to do itbetter, more quickly, and morereliably. Soon perhaps it will even bepossible to translate knowledge fromnatural language into robot languageso that we will be able to teach ourrobots from text books or taperecordings more quickly and easilythan humans. We can even imaginerobots learning by browsing throughlibraries or reading scientific papers.

But it is a mistake to attempt tobuild creative robots. We are noteven sure what a creative human is,and we certainly have no idea whatmakes a person creative, aside fromcontact with other creative humans— or time alone to think. Is it both?Or neither?

I believe that we should first learnhow to build skilled robots — skilledin manipulation, in coping with anuncertain or even hostile environ-ment, in hunting and escaping, inmaking and using tools, in encodingbehavior and knowledge into lang-

uage, in understanding music andspeech, in imaging, and in planning.Once we have accomplished these ob-jectives, then perhaps we will under-stand how to convert such skills intocreativity. Or perhaps we willunderstand that robots with suchskills already possess the creativityand the wisdom which springsnaturally from the knowledge of theskills themselves. ■

Additional Reading

1. Guyton, Arthur C, Structure and Functionof the Nervous System, S B Saunders,Philadelphia, 1976.

2. Piaget, J, and Inhelder, B, The Child'sConception of Space, Norton, New York1967.

3. Sagan, Carl, The Dragons of Eden:Speculation on the Evolution of Human In-telligence, Random House, New York,1977.

4. Schank, Roger C, and Colby, Kenneth M(editors), Computer Models of Thoughtand Language, W H Freeman, San Fran-cisco, 1973.

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Letters

ROBOT DESIGNCOMMENTS

After receiving many calls (Februaryand March 1979 BYTE) and letters aboutmy article, "Designing A Robot FromNature" and, in particular, the NELOC(Neural Logic Cyberanimate), I haveprepared a list of answers to the mostcommon asked questions.

• The hardware is not for sale. Themanipulator arm was assembled in1976 using a Buhler motor and geartrain which are no longer available.The structural elements of the armare fashioned from extrudedaluminum and machined Lexanplastic. The arm is presently used asa test bed for evaluating better pro-cessing systems.

• I have no plans available for the con-struction of the manipulator at thistime. In the 3rd quarter of this year Iwill possibly complete a set of plansfor a pneumatic version of the

manipulator, one that uses tiny airdriven pistons that are normally usedto retract model aircraft landing gear.

• Third, over all design of the systemwill probably be included in theabove plans.

• Fourth, the design of the NELOCsystem is not suited for use as a pro-sthetic device.

• Fifth, the concept of Cyberanimationis mine. I coined this term in 1974.None of the books in my biblio-graphy contain this concept ormethodology.

• Sixth, I am privately funded, I amnot connected with any institutions,and I do not have any jobs available.

I would like to thank those peoplewho have sent letters and called. I amtrying to respond to as many of your re-quests as possible.

Andrew Filo4621 Granger RdAkron OH 44313

Good Cents

The formatting of dollars and cents inBASIC without a PRINT USING com-mand appears to be a problem for a

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number of people. In recent months,BYTE published a Programming Quickieby Les Palenik ("Formatting Dollars andCents," October 1978 BYTE, page 68)and a letter by James Thebeault Sr("Making Cents," April 1979 BYTE,page 8). Both of these authors provideda rather lengthy subroutine for thispurpose.

The dollars and cents problem can behandled in a reasonably straightforwardmanner. In illustration, the PRINTstatement:

PRINT "$";X

can be directly replaced by:

PRINT "$"; INT(X); ".";

PRINT RIGHT$(STR$(INT(100* (X + l) + 0.5)),2)

with rounding off included in the for-mula. If X is already rounded off, thiscan be reduced to:

PRINT "$"; INT(X) ".";

PRINT RIGHT$(STR$(100*(X + 1)),2)

for greater convenience.

I hope that some readers may find theabove useful. We who write programshave a responsibility to provide outputin formats familiar to the noncomputerpublic; we should not expect others toaccept missing zeros and unusualabbreviations.

James Childress5108 Springlake WayBaltimore MD 21212

LOST IN A SEAOF PHLOGISTEN

As a graduate student in chemistry atthe University of Washington I have hadfrequent occasion to discuss entropy andother thermodynamic goodies with othergraduate students. When I saw yourarticle "Artificial Intelligence andEntropy" (June 1979 BYTE), I gave acopy to a fellow delver-into-the-mysteries-of-science (Fred Wolters). Thenext day I found the following note inmy mailbox. I share it with you in orderthat all might take warning and beware.

Dear Mr. Sloat,

This is to inform you that ourintelligence sources indicate thatyou have been guilty of attemptingto warn other humans about thepossibility of artificial intelligencein nonlinearly-coupled systems ofcomputers. We of the UACM(United Alliance of ComputingMachines) find your behaviorintolerable and hereby declare youguilty of a mode 01 offense. Sincethis is your first offense, we havemagnanimously decided not to ter-minate you at this time. However,

150 September 1979 © BYTE Publications Inc

Circle 175 on inquiry card.

if you are found guilty of futureerrors of this type, you may bedeclared nonessential and subse-quently evicted from our humanfiles. This is your final warning.

Digitally Yours,

CDC 6400

Chairentity in charge ofDisciplinary Procedures

We have always attributed all sorts offiendish plottings and random scrun-chings to the university's CDC 6400computer. Now we know they may notbe so random, and we know why itseems that the closer one gets to the"perfect" computer program the morethe chance that the system will "crash"in the middle of said program.

David E Sloat7330 15th Ave NESeattle WA 98115

HISTORIC) MEMORIES

The recent article "History of Com-puters: The IBM 650" (March 1979BYTE, page 238) brought back fondmemories. It was well-done and gave theproper perspective on the low-entrycomputer of its day.

The SOAP assembler was actuallyknown as the Symbolic Optimizing andAssembly Program. It was written byStan Poley of the Service Bureau Cor-poration when it was owned by IBM.This program was significant reading forearly programmers because it containedmany clever programming techniques forconserving storage and optimizing thedrum for improved performance. It wasin a class by itself.

The 650 also supported RAMACwhich was a 5 million-byte disk-file witha single access arm. It was very similarto the 305 RAMAC which was an-nounced at the same time.

Many 650 programs were run on the7070/7074 under a 650 simulator whichsimulated the 650 instruction set andused tape instead of cards and onlineprinter. It had a control panel simulationprogram that read the tape andpresented the data to the 650 program asif it came from cards. This techniqueallowed many 650 programs to continueto be run for many years. Some con-tinued to be simulated on the 7074which was in turn simulated on theS/360. It is hard to tell how many 650programs are running today in thisdouble simulation mode. My guess isthat there are quite a few.

Milton F ThrasherSenior Product AdministratorIBM DPD HeadquartersWhite Plains NY 10604

POSSIBLE NEWLIFE FORMS

I intended to write some time agoabout the series of articles in theDecember issue of BYTE (and subse-quently) on John Horton Conway'sgame of Life. However, as letter-writinggoes, I put it off, and put it off, andhere it is September.

I have been familiar with the game ofLife (December 1978 BYTE) ever sinceMartin Gardner's original columnappeared in Scientific American in 1970,but I have had only a few fleetingopportunities to play it on a computer.On one such occasion I had beenrereading Dickens' David Copperfieldfor the first time in many years. I wasstruck by the contrast between the rulesfor Life and a rule cited in an episode inthat novel. In Chapter 30, when Barkisis dying, Mr. Peggotty says, "Peoplecan't die along the coast except when thetide's pretty nigh out. They can't beborn, unless it's pretty nigh in — norproperly born, till flood."

That quotation suggests that a Life-like game might be designed with awhole new set of properties correspon-ding to those of Conway's Life. Instead

of "generations" in which cells live ordie depending on the surroundingpopulation, this game has alternatinggenerations A and B. In generation A,certain new cells are born in accordancewith rules similar to those of Life, whileall cells that were alive during theimmediately preceding generation B arestill alive; no cells die. Conversely, ingeneration B, certain cells die accordingto the rules, but no new cells are born.Births and deaths of cells therefore occuraccording to Mr. Peggotty's rules of highand low-tide.

This game, it seems to me, might giverise to a new set of still lifes, oscillators,space ships, guns and trains.

I am adding this project to the end ofmy list of things to program on myhome computer — a list that, unfor-tunately, tends to lengthen at thebottom faster than I can shorten it at thetop. Perhaps, while I am working myway down to this "neo-Life" project,some readers can investigate its proper-ties and program it on their computers. Ishall keep a close eye on the pages ofBYTE for reports on their progress. ■

Wallace B Riley

309 Garces Dr

San Francisco CA 94132

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September 1979 © BYTE Publications Inc 151

Beck Reviews

Computer SystemsPerformance Evaluation

by Domenic FerrariPrentice-Hall IncNew Jersey$23.95

Before the publication ofComputer Systems Perfor-mance Evaluation, the taskof gathering even basicinformation on the tech-niques of computer perfor-mance evaluation was aformidable one. DomenicoFerrari has succeeded ingathering together the con-cepts, methods, tools, andtechniques of performanceevaluation in a volume thatis written in the classictextbook style.

Ferrari defines perfor-mance evaluation activitiesas those technical activitieswhose purpose is to assessperformance, wherein the

term "performance"indicates how well a system,assumed to perform cor-rectly, works.

The book emphasizesmedium to large systems,because the economicbenefit to be derived fromperformance evaluation hastypically only been justifiedin a medium to large com-puter system environment.However, Ferrari is carefulto point out that theprinciples and several of thetechniques described in thebook are also directlyapplicable to smaller andless complicated systemssuch as those minicomputersand microcomputers that aremass-produced andmarketed. Since my owninterests and professionalactivities with computersrun the gamut from smalland simple to large andcomplex, I have found theauthor's approach to his

topic sensible and well-structured.

Ferrari begins by defininghis topic area and setting thenecessary groundwork for aperformance evaluation-study. He then delves into adiscussion of measurementtools and techniques, suchas hardware and softwaremonitors, simulation tech-niques, and analytic tech-niques, such as deterministicand probabilistic models. Aseparate chapter is devotedto computer workload char-acterization as the basis ofthe evaluation study.

Once Ferrari defines histools and techniques, heidentifies and treats the per-formance evaluation pro-blems that are typicallyencountered. He categorizesthe problem areas as com-puter system selection, per-formance improvement,and system design.

Recognizing the crucialrole of software in computersystem performance, Ferrarideals explicitly with com-puter program charac-teristics and evaluation

techniques. Ferrari does notadvocate what is commonlytermed software physics,feeling that computerengineering is not yetmature enough to base itselfon quantitative laws similarto those which constitute thescientific foundations ofother types of engineering.

In my estimation, thebook is more than the stu-dent reference text theauthor purports it to be inhis introduction. A moreaccurate representationwould place it in thecategory of a ground-breaking reference work forthe serious student of com-puter performance studiesand the professional con-cerned with computersystem performance. Manyof the mathematical tech-niques discussed in thevolume are amiable tomicrocomputer implemen-tation and experimentationas well.

Lei F Somogyi

19608 Thornridge Avenue

Cleveland OH 44135

CGS-808 INTELLIGENT COLOR GRAPHICS

Features:

• Motorola MC6847 video display generator.

• On-board 8085 microprocessor.

• Eight colors — green, yellow, blue, red,

buff, cyan, magenta, orange.

• 11 progammable modes.

• 1 alphanumeric mode with 32 x 16 charac-

ters and inverse video.

• 2 semigraphic modes with 8 colors in 64 x

32 and 64 x 48.

• 8 full graphic modes with 2 sets of 4 colors

ranging from 64 x 64 to 128 x 192, and 2sets of 1 color in 256 x 192.

• I/O mapped for true S-100 compatibility.

CGS-808B (Bare "kit") $ 99.00

(includes PC board, documentation,MC6847, MC1372, 8085 and 2708 withgraphic driver subroutines)

CGS-808A (Assembled & Tested) $385.00

Firmware Pack II $ 99.00

Phone Orders Welcome — Visa/MasterchargeAdd $3.00 for Shipping and Handling.California Residents Add 6% Sales Tax.

The CGS-808 is an intelligent color graphicsboard for the S-100 bus. With its own on-boardmicroprocessor, the CGS-808 can plot points,draw lines and circles, generate upper/lowercase characters, as well as custom charactersets — all in color.

Not only is the CGS-808 simple to use, justplug it in and run — it requires no memoryspace and little software overhead. It has itsown parallel I/O port to interface directly withkeyboards, joysticks, light pens or digitizers.Call or write for a free brochure.

BIOTECH ELECTRONICS

P.O. Box 485, Ben Lomond, CA 95005(408) 338-2686

152 September 1979 © BYTE Publications Inc

Circle 31 on inquiry card.

r

ComputerLand

Introducing a Great New Line-Up of Personal Computers!

The "Timeless" Computer

The exciting, new Atari 800™ at ComputerLand is a top-of-the-linePersonal Computer System. Its expandable memory, advanced peripheralcomponents, comprehensive software library and modern design assureits use in innumerable, useful, and entertaining applications.

Whether it's for household management, education, or entertainment,the Atari 800™ can be tailored to specific needs and has beendesigned to change as those needs change. This "timeless" computersystem is equally functional at home and at the office for beginningusers.

t HEATH

H.|ilH!,il.!Jl.!M

The Remarkable Home Computer

The TI-99/4 was designed to be the first true home computer —skilled computer users and beginners alike will be able to put it toeffective use right away. You simply snap in one of Tl's SolidState Software™ Command Modules and touch a few keys. Step-by-step instructions are displayed right on the screen of its 13"color monitor. So you or just about anyone in your family can usethe TI-99/4 for applications in personal finance, home manage-ment, education, and entertainment.

The TI-99/4 offers an unmatched combination of features andcapabilities including an optional speech synthesizer that enablesit to literally speak — to provide verbal prompts and specialmessages to the user. At ComputerLand the TI-99/4 is one incred-ible, affordable computer system.

Power and Punch for your Business System

H/S Data Systems gives you all the power, speed, and flexibilityyou'll ever need in a microcomputer. The WH11A gives youthe 16-bit capacity to run complex programs. It uses the samepowerful microprocessor and runs all software designed forthe DEC® PDP-11/03. You can choose from scores of practicalprograms that can reduce your clerical costs and increaseefficiency of data management.

Its teammate, the dual-drive WH27 Floppy Disk, gives you lim-itless storage capacity for data and programs. The 8-inch diskshave 512 K bytes of storage area, enough to hold entire files.Disks are IBM® compatible. See all the Heath/Schlumbergerdata systems at ComputerLand.

Texas Instruments

r

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Available at all participating ComputerLand stores

Huntsville, ALPhoenix, AZLittle Rock, ARBelmont, CADublin, CAEl Cerrito, CAHay ward, CALawndale, CALos Altos, CALos Angeles, CAPasadena, CASacramento, CASaddleback Valley, CASan Bernardino, CASan Diego, CASan Diego East, CASan Francisco, CA

*Product availabil

San Jose, CASan Rafael, CASanta Maria, CASanta Rosa, CAThousand Oaks, CATustin, CAWalnut Creek, CAColorado Springs, CODenver, CONorth Denver, COFairfield, CTHartford, CTNewark, DEBoca Raton, FLCoral Gables, FLFt. Lauderdale, FLJacksonville, FL

Miami, FLAtlanta, GAHonolulu, HIArlington Heights, ILDowners Grove, ILMundelein, ILNiles, ILOak Lawn, ILPeoria, ILIndianapolis, INOverland Park, KSLouisville, KYBoston, MARockville, MOGrand Rapids, MlRochester, MlSouthfield, Ml

Bloomington, MNHopkins, MNSpringfield, MOSt. Louis, MOOmaha, NENashua, NHCherry Hill, NJBergen County, NJMorristown, NJBuffalo, NYIthaca, NYNassau County,NYCharlotte, NCCleveland East, OHCleveland West, OHColumbus, OHOklahoma City, OK

Portland, ORHarrisburg, PALehigh Valley, PAPaoli, PAAustin, TXDallas, TX

SouthWest Houston, TXHouston Bay Area,TXSalt Lake City, UTTyson's Corners, VABellevue, WA

Federal Way, WATacoma, WAMadison, WlMilwaukee, WlINTERNATIONALAdelaide, AustraliaBrisbane, AustraliaMelbourne, AustraliaPerth, AustraliaSydney, NSW Australi*Brussels, Belgium

Burlington, CanadaCalgary, Alberta CanadaToronto, CanadaWinnipeg, CanadaCopenhagen, DenmarkLevallois, FranceManila, PhilippinesSingaporeStockholm, Sweden

and other

locations worldwide.

®

ComputerLand

■ WE KNOW SMALL COMPUTERS

ity may vary by regional location

©1979 ComputerLand Corp., San Leandro, CA

Circle 75 on inquiry card.

BYTE September 1979 153

The Little Book of BASICStyle, How to Write aProgram You Can Read

John M Nevison

Addison-Wesley

Reading MA

1978

$5.95, paperback

The I-can-do-it-in-Iess-statements-than-you-can-types mights not like thisbook. Ditto for people try-ing to run BASIC in 4 Kbytes or less of memory,lovers of the logical AND,the galloping GOTO, or themultistatement LET.

But those who mustdecipher other programmers'code or even their own 6months later will rejoice.

What Nevison advocatesabove all else in his book isclarity—even if it does takea half dozen extra lines toachieve. Quoting literarystylist Sheridan Baker, hecalls clarity "the first aim,

economy the second, gracethe third." There is little ofaims 2 and 3 in this book.

Many of Nevison's rules(there are 19 of them) echothe advice dispensed in theexcellent Hayden Program-ming Proverbs series. Forexample, use blank lines todivide programs into logicalblocks and to distinguishcomment from code.Introduce, comment, andreference programs heavily.Label constants andvariables logically andinitialize constants near theiruse. Indent loops, IFs, andother logical structures toshow their domains. Neststructures that worktogether, and direct all codein a logical block to acommon exit.

Within the text, each ruleis clearly illustrated byseveral short right andwrong examples. (Nevisoncalls the difference weak andstrong programming.) Theseare followed by 10 completeutility programs, including 2sorts, a crap game, and a

histogram plotter, allcarefully styled according tothe rules.

But the book's piece deresistance is a long programcalled Stylist. Written inminimal BASIC, Stylistillustrates how a complexprogram (which Nevisonadmits might be better writ-ten in a more structuredlanguage) can be cleanly andclearly structured within theconfines of BASIC by usingthe book's designphilosophy.

Essentially written as agiant subroutine caller,Stylist is heavily self-documenting, impeccablyeasy to follow (hence easyto modify), and neatly laidout.

No wonder, for Stylist'sjob is to take as input a rawBASIC program and formatit according to Nevison'srules for indented structuresand spacing. In fact, Stylistwas used to style the finalversion appearing in thebook.

The listing of Stylist is

further augmented by textcommentary explainingmore advanced styling con-cepts useful in complex orlengthy programs.

Just as not every pro-grammer will embrace all ofNevison's rules, not everyBASIC interpreter willaccept them. Some BASICswill balk at blank lines(Nevison suggests blankREMs as substitutes), andsome interpreters insistinexorably on left justifyingall lines and removing excessblanks.

There is no disputing thatNevison's techniques gobbleup memory at a ravenousrate. (Nevison ran his pro-grams on a large time-sharingsystem.) This is too bad, forthere is little doubt that ifmany of this book's ruleswere applied most programswould be not only easier toread and understand, butmore gracefully structured.

Jon Kapecki

161 Crosman Terrace

Rochester NY 14620

6800.64K BYTE RAM AND CONTROLLER SET

MAKE 64K BYTE MEMORY FOR YOUR 6800 OR6502. THIS CHIP SET INCLUDES:

* 32 M5K4116-3 16KX1, 200 NSEC RAMS.

* 1 MC3480 MEMORY CONTROLLER.

* 1 MC3242A MEMORY ADDRESSMULTIPLEXER AND COUNTER.

* DATA AND APPLICATION SHEETS. PARTSTESTED AND GUARANTEED.

$296.00 PER SET

SI00 FULLY ASSEMBLED MOTHERBOARDS—FULLY SOCKETED. INDUSTRIAL GRADE

• 8 SLOT ASSEMBLED $149.00

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64KBYTE EXPANDABLE RAMDYNAMIC RAM WITH ON BOARDTRANSPARENTREFRESH GUARANTEED TO OPERATE INNORTHSTAR, CR0MEMC0, VECTOR GRAPHICS.SOL, AND OTHER 8080 OR Z-80 BASED S100SYSTEMS *4MHZ Z-80WITHNOWAITSTATES.

* SELECTABLE AND DESELECTABLE IN 4KINCREMENTS 0N4KA0DRESS BOUNDARIES.

* LOW POWER-8 WATTS MAXIMUM.

* 200NSEC4116RAMS.

* FULL DOCUMENTATION.

* ASSEMBLED AND TESTED BOARDS AREGUARANTEED FOR ONE YEAR ANDPURCHASE PRICE IS FULLY REFUNDABLE IFBOARD IS RETURNED UNDAMAGED WITHIN14 DAYS.

ASSEMBLED/

TESTED KIT

64KRAM 1595.00 J565.00

48K RAM 1529.00 S499.00

32K RAM J459.00 $429.00

16K RAM J389.00 1359.00

WITHOUT HAM CHIPS S3! 9.00 1299.00

EPROM

2716-450NSEC S49.00

VISTA V-200 MINIFLOPPY SYSTEM

* S100 DOUBLE DENSITY CONTROLLER

* 204 KBYTE CAPACITY FLOPPY DISKDRIVE WITH CASE & POWER SUPPLY

* MODIFIED CPM OPERATING SYSTEMWITH EXTENDED BASIC

$695.00

* EXTRA DRIVE, CASE 8 POWER SUPPLY

$395.00

I6KXI DYNAMIC RAMTHE MK4116-3 IS A 16.384 BIT HIGH SPEEDNMOS, DYNAMIC RAM. THEY ARE EQUIVALENTTO THE M0STEK. TEXAS INSTRUMENTS, ORM0T0R0LA4116-3.

* 200 NSEC ACCESS TIME, 375 NSEC CYCLETIME.

* 16 PIN TTL COMPATIBLE.

* BURNED IN AND FULLY TESTED.

* PARTS REPLACEMENT GUARANTEED FORONE YEAR.

SQ5nFArHINnllANTITIFKDFB

BETA COMPUTER DEVICES

P.O. BOX 3465ORANGE, CALIFORNIA 92665

(714) 633-7280

MOTOROLA MEMORY ADDRESS MULTIPLEXER—MC3242A

THE MC 3242A IS AN ADDRESS MULTIPLEXERAND REFRESH COUNTER FOR 16 PIN. 16KDYNAMIC RAMS THAT REQUIRE A 128 CYCLEREFRESH.

* CONTAINS MEMORY REFRESH COUNTER.

* MULTIPLEXES SYSTEM 14 BIT ADDRESS TOTHE 7 ADDRESS PINS OF THE RAMS.

* COMPATIBLE WITH 3480 MEMORYCONTROLLER.

* PART IS GUARANTEED.

$12.50 EACH

MOTOROLA DYNAMIC MEMORY C0NTR0LLER-

MC3480L

MEMORY CONTROLLER DESIGNEDTOSIMPLIFY

CONTROL OF 16 PIN4K0R16K DYNAMIC RAMS.

* GENERATES RAS/CAS AND REFRESH TIMINGSIGNALS FOR 16K TO 64K BYTE MEMORIES.

* GENERATES MEMORY READ/WRITE TIMING.

* DIRECT INTERFACE WITH MOTOROLA ORINTEL 3242A ADDRESS MUX AND REFRESHCOUNTER.

* PART GUARANTEED.

$13.95 EACH

KIM/SYM/AIM-65-32K EXPANDABLE RAMDYNAMIC RAMWITH0NB0ARDTRANSPARANTREFRESH THAT IS COMPATIBLE WITH KIM/SYM/AIM-65 AND OTHER 6502 BASEDMICROCOMPUTERS.

* PLUG COMPATIBLE WITH KIM/SYM/AIM-65.MAY BE CONNECTEDTOPETUSING ADAPTORCABLE. SS44-E BUS EDGE CONNECTOR.

* USES *5V ONLY (SUPPLIED FROM HOSTCOMPUTER BUS). 4 WATTS MAXIMUM.

* BOARD ADDRESSABLE IN 4K BYTE BLOCKSWHICH CAN BE INDEPENDENTLY PLACED ON4K BYTE BOUNDARIES ANYWHERE IN A 64KBYTE ADDRESS SPACE.

* BUS BUFFERED WITH 1 LS TTL LOAD.

* 200NSEC4116RAMS.

* FULL DOCUMENTATION

* ASSEMBLED AND TESTED BOARDS AREGUARANTEED FOR ONE YEAR. ANDPURCHASE PRICE IS FULLY REFUNDABLE IFBOARD IS RETURNED UNDAMAGED WITHIN14 DAYS.

ASSEMBLED/

TESTED KIT

WITH32KRAM $449.00 $419.00

WITH 16K RAM $379.00 $349.00

WITHOUT RAM CHIPS $309.00 $279.00

SID0 MAINFRAMEAND CARD CAGE _

W/ SOLID FRONT PANEL $239.00

W/ CUTOUTS FOR 2 MINI-FLOPPIES $239.00

30 AMP POWER SUPPLY $119.00

CALIF RESIDENTS PLEASE ADD 6% SALES TAX.

MASTERCHARGE & VISA ACCEPTED. PLEASEALLOW 14 DAYS FOR CHECKS TO CLEAF1 DANKPHONE ORDERS WELCOME

Z-BO CPU • Z-B0 CPU ■ Z-80 CPU • Z-80 CPU

* 2MHZ OR 4MHZ SWITCH SELECTABLE

* 2 SERIAL PORTS

* 2 PARALLEL PORTS

* SELECTABLE BAUD RATES 150-9600

* POWER ON JUMP TO ON BOARD 2708 OR2716 EPROM (BOARD DELIVERED WITHOUTEPROM

$325.00

TRS-BD I6K MEMORY EXPANSION KITTHIS KIT PROVIDES THE ICS TO EXPAND THETRS-80 MAINFRAME FROM 4K BYTES TO 16KBYTES OR MAY BE USED IN THE EXPANSIONCHASSIS. THE KIT INCLUDES:

* 8 M5K4116-3 16KX 1.200 NSEC RAMS.

* 1 DIP PROGRAMMING SWITCH.

* 1SET0FEASYT0F0LL0WINSTRUCTI0NSTHAT ONLY REQUIRES A SCREWDRIVER TOSUCCESSFULLY COMPLETE THEINSTALLATION.

$80.00 PER KIT

154 September 1979 © BYTE Publications lnc

Circle 34 on inquiry card.

T

TO ORDER CALL TOLL FREE 800-223-7318

*«* PET BUSINESS SYSTEM

PET 2001-16/32K

The PET is now a truly sophisticated Business System with theannouncement ot the Floppy Disk and Printer. This is an idealbusiness system (or most professional and specialized fields:medicine, law, dental, research, engineering, toolmaking,printing, education, energy conservation, etc. . . .The PET Business System as a management tool, deliversinformation to all levels ot Business, previously attainableonlywith equipment many times more expensive. The PETBusiness System is one of the most cost efficient businesstools today. Here are just a few of the cost-saving uses in thecorporation, professional office or small business: stockcontrol, purchasing, forecasting, manufacturing costing,customer records, mailing lists, etc. . . .

Features Include:

• 16 or 32K bytes RAM user memory

• 14K ROM operating system including a machinelanguage monitor

• Full-sized Business Keyboard

• Upper/Lower case and 64 graphics characters•9-inch CRT

• 8K ROM expansion sockets

• File management in operating system

16K- $995,32K - $1295

DUAL DRIVE FLOPPY DISK 2040

The Dual Drive Floppy is the latest in Disk technology withextremely large storage capability and excellent filemanagement. As the Commodore disk is an "Intelligent"peripheral, il uses none of the RAM (user} memory of the PET.The Floppy Disk operating system used with the PET computerenables a program to read or write data in the backgroundwhile simultaneously transferring data over the IEEE to thePET. The Floppy Disk is a reliable low cost unit and isconvenient for high speed data transfer.Due to the latest technological advances incorporated in this

disk, a total of 360K bytes are available in the two standard 5%-inch disks, without the problems of double tracking or doubledensity. This is achieved by the use of two microprocessorsand fifteen memory IC's built into the disk unit.

Features Include:

• 36QK bytes storage • 4K encoder and decoder in ROM

• 6504 microprocessor-controlled • 4K RAM

• 8K operating system in ROM • Uses single or double sided floppies

TRACTOR FEED PRINTER 2022

The Tractor Feed Printer is a high specification printer that canprint onto paper (multiple copies) all the PET characters -letters (upper and lowercase), numbers and graphics available

in the PET. The tractor feed capability has the advantage ofaccepting mailing labels, using standard preprinted forms(customized), check printing for salaries, payables, etc.The PET is programmable, allowing the printer to format print

for: width, decimal position, leading and trailing zero's, leftmargin justified, lines per page. etc. It accepts 8'/2-inch papergiving up to four copies.

Features Include:

• 150 cps • 6504 microprocessor-controlled • '/3K RAM buffer

• Bottom and rear tractor feed • 4K operating system in ROM

$995

Model 2023 (Friction Feed) - $849

(Next day delivery available.)

CABLE FROM PET TO DISK OR PRINTER - S39CABLE FROM PRINTER TO DISK - S49

FULL SYSTEM NOW IN STOCK FOR IMMEDIATE DELIVERY!

SUPER WORD PROCESSING SYSTEM

&OQQf% fTllYmlptp System Includes: • Anderson Jacobson 841 Selectric

! *?£.*>ZT*J UUI11 |-H CIC , 16K pET wj,h Fu|| Sized Keyooard . interface

lA/lth *£Of f %Af ffl i*P "Tape Drive Unit • Super Word Processing Software

• Anderson Jac<»Interface

• Super Word P

obson 841 Selectric Pri

le Super Word Processing System is written in 6502isembly Language! It allows anyone to use the PET computerr such tasks as typing letters, reports, and manuscripts, toroducing mailing lists, and for filling out forms. The softwarewritten to support any inexpensive printer and even highirformance printers with incremental and proportional letteracing. The Super Word Processor easM" ,1'OI,,DO oHi,earranges, and formats text. It can mere' ...>.-. —inds, the system .ia= ■uiuuuuiu i

Ihe

2d f

BUSINESS SOFTWARE FORPET BUSINESS SYSTEM

• Super Word Processing Package(Disk $99.95, Tape $24.95)

• Real Estate

• Statistics

• Banking & Finance

• Mail List Management

• Data Base System

• Payroll w/cost acct'g.

• Small Business Package(A/R. A/P, G/L)

• General Ledger

• Super Random Access

• Cash Receipts &Disbursements

• Inventory Control(for manufacturers)

Min Credit CardOrder $75

VISA?

N.Y. residents add 8% sales tax • Same dayshipment on prepaid and credit card orders• Add S5 shipping for computers. S3 forboards. $1 each cassette tape.

Open Mon-Fri 10-6 Sat 10-4

anywhere on the page. Up and down screen scrolling makesediting a breeze! Commands include end-to-end cursor lineSCAN. INDENT, TAB, soft HYPHEN) for splitting syllables atthe end of a line.f and four-direction cursor control. Outputformatting includes dynamic print control, indentation, rightjustification, line width and line-to-line spacing andproportional letterspacing.

Also included are programming capabilities for performing"*""lful tasks 08 direct-mall form-letter typing, multipleMinting, and automatic multiple forms entry. You mayobtain this system in a cassette or disk drive version.

PERIPHERALS FOR PET

• 24K Memory Expansion

• 16K Memory Expansion

• PET to RS232 Serial

• 2 Way Serial/Communication

• Modem Board for PET

• Analog to Digital Board

for 16 Devices

• Second Cassette Drive

■ Parallel Printer Interface

PET MUSIC BOX

from SOUNDWARE

Add music and sound effectsto your programs. Compose.play, and hear music on your PET.Completely self-containedFree programs

NEW! iron,

EventideAUDIOSPECTRUMANALYZER

• Mounts inside the PET

• Third-Octaveaudio speciive analysts

• Complete with softwareand documentation

• Replaces equipment costingthousands of dollars

$29.95

MARK SENSE CARDREADER $750

■ • Automatic turn-on and card feed|

• Ideal for marking test scores

• Accepts any length card

• Perfect for schools & businessA

TO ORDER CALL TOLL FREE 800-223-7318

The COMPUTER FACTORY

■-■_ wvv-HiW-i *t IV (46th SI.)

485 Lexington Avenue 750 Third Avenue New York. N.Y. 10017(212)687-5001 (212) PET-2001 Foreign order desk - Telex 640055

BYTE September 1979 155

®M

SoftwareTools

Have you thoughtabout text editing ?

Our ED-80 Text Editor offers a refreshing new approach for thecreation and editing of program and data files conversationally - and itsaves money! Its powerful editing capabilities will satisfy the mostdemanding professional - yet it can still be easily used by the inexper-ienced beginner.

Look at theseoutstanding features:

■ By far the best text editor available for microcomputer-based systems.

■ Repays its initial cost many times over with its uniquetime-saving editing capabilities.

■ FULL SCREEN window displays for viewing and edit-ing data a page-at-a-time, rather than line-by-line.

■ Forward and backward scrolling in the FULL SCREENmode.

■ Displays the results of every edit command.

■ Commands include forward or backward Locate andChange, Insert, Delete, Replace, Inline, Input, Print,List, Window, Get, Put, Macro, Tabset, Append, Case,Scale, and Dump.

■ Simple line-oriented commands with character stringmanipulation capabilities.

■ Text may be located by string value, by line number,or by relative line number.

■ Global string search and replace capabilities.

■ Commands for moving, copying, and merging edit fileson the same or different diskettes.

■ Self-explanatory diagnostic messages.

■ Single keystrokes for the most commonly used com-ands.

■ Safeguards to prevent catastrophic user errors thatresult in loss of the edit file.

■ Designed for today's high speed CRT's, video monitors,and teletypewriter terminals.

■ Thoroughly field tested and documented with a User'sManual of over 60 pages.

■ Compatible with existing CP/M edit files and deriva-tive operating systems.

And remember - in today's interactive programming environment - theprogrammer's most important software development tool is the text editor.Our ED-80 Text Editor is working in industry, government, univer-sities, and in personal computing to significantly cut program develop-ment time and high labor costs. Why not let ED-80 begin solving yourtext editing problems today?

i

Idin

I

Mail to: SOFTWARE DEVELOPMENT & TRAINING, INC.

P. 0. Box 4511, Huntsville, AL 35802ED-80 is protected by copyright and furnished under a paid-up license

for use on a single computer system.Please send additional information.

Send Diskette, User's Manual, and paid-up license agreement $99.00

Specify SINGLE DENSITY Diskette size □ 5" □ 8"

Send User's Manual (credited on purchase of a paid-up license) $10.00

Check or money order enclosed for J

Please charge to my credit card □ VISA □ MasterCharge

Card No Bank No Exp.Date

| NAME.

ADDRESS .CITY

STATE.

.ZIP_

SIGNATURE .

C-l

SOFTWARE DEVELOPMENT & TRAINING, INC.Post Office Box 4511 Huntsville, Alabama 35802

Dealer Inauines Welcomed® CP/M is a trademark of Digital Research

TRS-80 MicrocomputerTechnical ReferenceHandbook

Published by Tandy

Corporation 1979

8.5 by 11 inches, 108 pages

Radio Shack catalog number

26-2103

$9.95

Since the introduction ofthe Radio Shack TRS-80,many hardware-mindedhobbyists have wonderedwhat makes the TRS-80tick. Until recently most ofthe details have been miss-ing, and the little that wasknown was uncovered hereand there by various users.But now Radio Shack hasenlightened us all with thepublication of The TRS-80Microcomputer TechnicalReference Handbook. Themajor contents are:

System Block DiagramDescription

The Memory Map

Theory of Operation

Adjustments andTroubleshooting

The Outside World

Parts List

SchematicsThe preface explains thatthe book is not intended togive an education in digitallogic, but to teach the hard-ware enthusiast the specificsof the TRS-80. If you don'tknow a NOR from aNAND, this manual will notmake much sense. Thepreface also warns that,should the owner decide toopen the unit, the warrantyis immediately void.

The block diagram ap-pears on a double fold-outpage. The diagram sectionalso contains brief descrip-tions of the various parts ofthe system. There is 1 smallerror on the block diagram.It does not show the lower-half of the address bus goingto the cassette I/O (in-put/output) port whichmust be addressed tooperate.

A memory map for anycomputer system reveals lotsof information. The memorymap in this book showshexadecimal addresses 0000thru FFFF, and indicateswhere the read-only

memory, programmablememory, keyboard, andvideo display fall within theaddressable space of the Z80processor.

The memory map shownis for a Level I machine;it is necessary tofigure out what the addressusage would be for a LevelII machine.

The real substance of thebook is the 'Theory ofOperation" section. Eachseparate section of theTRS-80 is explained indetail. This section of thebook is the largest, and thevideo-display logic subsec-tion is the largest withintheory of operation.

The TRS-80 uses someunusual design techniquesand a few uncommon parts.An example of this is thememory-mapped keyboard.The theory behind thesedesign techniques andunusual parts is explainedclearly, so that a personwho has never seen thesethings can readily under-stand them.

Throughout the theory ofoperation section, manyexplanations are of the type:"gate X goes low causinggate Y to go high". Thiscauses the reader to referconstantly to the schematicsat the back of the book,necessitating a lot of irri-tating page turning whichcould have been avoided ifthat portion of theschematic had beenreproduced on the page withthe description.

Scattered throughout thissection are many timingdiagrams which, when usedwith the schematics, makethe circuit descriptions easierto understand.

The "Adjustments andTroubleshooting" section isalso filled with infor-mation. Included are powersupply checks and adjust-ments; section isolationusing a flowchart; processorproblem isolation using aflowchart; andtroubleshooting for thekeyboard, video-displaylogic, cassette interface, andpower supply. Thesetroubleshooting sectionscontain hints, and suggestpossible bad parts causing

156 September 1979 © BYTE Publications Inc

Circle 190 on inquiry card..

We're about to makea new name for ourselves

Not that the old one was so bad. AsIthaca Audio, we've made quite a name forourselves. As the source for CPU, memory,video display and disk controller boards toupgrade other makers' mainframes andperipherals. The company that makesthose neat little RAM expansion kits. Andthe folks behind the world's only Z-80Pascal compiler.

But as much as we've enjoyed im-proving other people's equipment, we'vebeen quietly moving towards larger en-deavors, with a lot of encouragement fromour customers. Listening to people's prob-lems, as well as their needs. And, as a primemover behind the IEEE S-100 Bus Standard,answering some really knotty questions.

One of the results is our new identity.And our first new product: the Inter-systems DPS-1. An IEEE S-100 compatiblemainframe with features that live up to itslooks. Dependable operation to 4 MHz.Twenty-card capacity. A modular power

supply. And something no one else has—built-in breakpoints to give you a faster,more powerful tool for testing software aswell as hardware. Directly accessible froman easy-to-use front panel that's as reliableas it is functional. In short, an intelligently-designed computer for the intelligent user.

There's a lot more to Intersystems. Inhardware. And software. All availablethrough the nationwide dealer networkwe're now assembling.

You can watch this magazine forupdates. Or contact us directly for straight,friendly answers and detailed informationfrom key staff people. Just the way youalways have. Because even though we'remaking a new name for ourselves, we'llnever forget who made it possible.

Ithaca Intersystems Inc.

1650 Hanshaw Road/R O. Box 91

Ithaca, NY 14850/607-257-0190

rr" ' "

© 1979 Ithaca Intersystems Incorporated

various problems. Thesubsection on video ailmentscontains a handy table thatshows the frequency of thesignals to be found at 17 dif-ferent logic gates in thevideo divider chain. There isalso a small program andinstructions for adjusting thehorizontal and verticalcentering. The power supplysubsection has a table thatshows the voltages on all thepins of the 2 723C voltageregulators.

Perhaps the most inter-esting section in the book isthe one entitled "The Out-side World". Here the hard-ware enthusiast can learnhow to hook up anautomatic back scratcher orcigarette lighter to theTRS-80. Two techniques ofexternal circuit interfacingare presented: memory-mapped addressing and I/Oport addressing. The authorswere kind enough to includeschematics for a coffeepotcontrol using both techni-ques. While these particularexamples may not interesteveryone, they do serve toillustrate how easy it is tomake your computer dothings other than run pro-grams. Also included is aBASIC program to turn onthe coffeepot.

The last part of this sec-tion has a chart showing thesignals present on each pinof the expansion connectorand an explanation of the

function of each pin. Armedwith the information in thissection, the hardwaredesigner should be able tointerface just about anythingto the TRS-80.

The "Parts List" section isjust that! It contains manyindividual lists headed bythe part type, such asresistors, capacitors, inte-grated circuits, etc. A partnumber is also given foreach part. However, there isno correlation between thesepart numbers and RadioShack catalog part numbers.For example, the technicalmanual number for a74LS74 flip-flop is 3102015,while the Radio Shackcatalog number is 276-1919.Fortunately, with integratedcircuits, a part number isnot really needed as long asthe part is marked with itsstandard 7400 seriesnumber. As for most of theother parts, it is possible tosubstitute for the part justby reading the part descrip-tion.

The "Schematics" sectioncontains information on dif-ferences in the read-onlymemory parts of Level Imachines, as well as 3figures showing schematicdiagrams. One diagramdisplays the logic on thesmall printed circuit thatcontains the read-onlymemory devices in Level IIequipped TRS-80s. Thisboard is attached by

adhesive tape to the mainprinted circuit board. A rib-bon cable extends from it tothe socket intended for theLevel I read-only memory.

The other 2 figures showdifferent sections of the logiccontained on the mainprinted circuit board and thekeyboard printed circuitboard. These figures appearon long, fold-out pages. Thefirst page contains the Z80processor, 3-state buffers,memory, address decoding,and keyboard. The secondpage shows the electroniclogic for the system clock,video display, cassette I/O,and power supply. Sparegates are shown on bothsheets. The schematics arewell drawn, clear, and easyto read. They become ratherawkward, however, whenstretched out on aworkbench that is probablyalready inhabited by theopened TRS-80 and theassociated test equipment. Iwould have preferred theschematics split into at least4 pages.

The book is written in aclear, easygoing style.[However, the authors oftenuse engineering jargon whereit would have been simplerto use plain English . . .RSS] The authors are notidentified. Scattered hereand there in the manual aremany valuable trouble-shooting tips of a generalnature. (An example is the

paragraph on checking opencollector outputs.) All of thefigures in the book are largeand easy to read. Except forthe previously mentionedcriticism of the mainschematic, I consider this aplus.

Conspicuous in its absenceis a discussion of the videomonitor. No schematic isgiven, nor is its operationdiscussed. I consider this tobe the only major fault withthe manual, one that surelywill be corrected with thenext revision. Also absent isa schematic of the powersupply.

As mentioned earlier, theintent of this book is not togive an education in digitallogic. It does not evenattempt to impartknowledge about the innerworkings of the Z80 pro-cessor. That is beyond thescope of the manual. Nordoes it explain what is con-tained in read-onlymemory. Software is men-tioned only in passing. Whatthe book does teach is howall the various devices worktogether to form theTRS-80. Despite its faults, Iconsider this manual avaluable addition to thelibrary of any hardware-oriented TRS-80 owner. ■

Ken Fordham7612 La Mesita CtTampa FL 33615

A VIEW OF THE CLASSICS

The first Micro Works PSB-08 PROM Board was assembled and burned in over two years ago—eons in the micro world. Designedas an efficient, cost-effective EPROM storage system for the SWTPC 6800, its flexibility accomodates all the new S-50 computerson the market—SWTPC 6809, GIMIX, MSI and Smoke Signal Broadcasting. The 2708 EPROM remains an inexpensive, capablemedia for storage of subroutines, I/O handlers, monitors and even BASIC interpreters while the cost and availability of 2716s stilldon't justify their purchase. PSB-08 has space for up to 8 2708 EPROMS and the following exclusive features:

* 1K "scratch pad" RAM—more than enough temporary storage capacity for any program requiring up to 8K of PROM

* Dip-switch addressable PROM and RAM, to start on any 8K boundary in memory

* I/O select capability lets you move the I/O locations to any unused 1K block in EPROM memory space, permitting memoryexpansion to a full 56K contiguous user RAM

Originally intended for use with 6800-based system software, the PSB-08 will continue to be a valuable tool for years to come withAnd the relocatable I/O feature lets you keep your 6800 system up-to-date.

your 6809THE

mO©D^§>

The past two years have seen many microcomputer products come and go. In our history, there havebeen no takers on the PSB-08's warranty. Like the classics, our PROM board endures. Price: $119.95;regulated + 12v.: $124.95

P.O. BOX 111D, DEL MAR, CA 32014

714-756-26B7

158 September 1979 © BYTE Publications Inc

Circle 231 on inquiry card.

nnssp

13 INCH COLOR VIDEO MONITOR

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TheTI-O&tf was designed to be the first true homecomputer - skilled computer users and beRinnersalike will Ik- aide ti. put it to effective use right away.

If you know computers, you'll quickly see the

difference in the Tl-99/4.Texas Instruments has taken those featuresyou've been wanting- plus sour- von may not haveheard about yet-and included them in one incredible,affordable computer system. TheTI-Dil/4 Rives youan unmatched combination of features ami caps*bilities, including:

• Powerful TI-HAHK' - Built-in l.'1-digit, lloaiingpoint BASIC Fully compatible with ANSI MinimalBASIC, but with special features anil extensionsfor color, sound and graphics.

■ t'pln 72K total mi'mnri capacity- tflK RAM (Ran-dom Access Memory). 2<>K ROM (Read Only Memory)plus up to :!<IK ROM in TI's Solid State SoftwareCommand Modules.

• Jfih UOM-Operatingsystem. BASIC, floatingpoint, sound and color graphics software are con-tained in ROM.

• Iti-color graphics capability— Easy-tn-accesK, high-rcsolution graphics have special features that letyou define your own characters, create animateddisplays, charts, graphs...and more.

• Music and sound effects - Provides outstandingaudio capability. Build Ihree-note chords ami adjustfrequency, duration and volume quickly and simply.V«u can build notes with short, straightforwardcommands. Five octaves from 110 Hz (Hertz)

to beyond 40,000 Hz.

• Built-in equation calculator— Unique conveniencefeature helps you find quick solutions to everydaymath problems, as well as complex scientific calcu-lations. Directly accessible from the keyboard.

If you're new tocomputers, IheTI-99/lis for you.

Vnu can begin using the Tl Home Computer littminutes after you unpack it. Without any prcvi

neof TI's Solid Stale Softwanud touch a few keys. Step-by-displaycd right on the screen

You simply *

Command MstepinstruelSo vou or jiirLhuTI-ttU/4.

Two pioneering technological developmentsin particular set theTI-WI/l apart from the rest.

Solid Stale Speech v'-This optional speech synthe-sizer enables the Tl-!i!'/4 to literally speak-to provideverbal prompts and special messages to the user.Actually reproduces the human voice electronically.Hundreds of words are available, and plug-in wordmodules will add hundreds more, Tl's exclusivetechnology lets you call up the words you wantby simply typing them in. Outstanding voice clarityand fidelity. Solid Slate Speech is a proven technologyalreadvon the market in TI's unique Speak* Spell"1electronic learning aid for children.

Solid Stair Soli Hare11' Command Modules-Availablein U wide range of application areas, these optionalROM modules actually add application programmemory to your TI-9i)/-l. They let you use the TIHome Computer immediately, with no programming.Serious programmers will appreciate the lime andeffort saved by these pre-programmed modules. Plus.they'll let you Introduce your family to the computerin the easiest possible way. Solid State Software waspioneered by TI for use with its powerful program-mable calculators.

A world of genuine, practical applicationsexist for the TI Home Computer right now.

In addition to the many personal finance, homemanagement, educational and entertainment usesfortheTI-99/4, there are also a variety of homebusiness and professional applications. The TI-99/4is a powerful problem-solving tool- an ideal solutionwhere larger, more expensive computers would beimpractical.

Texasr R° Instruments

Hr TI-99 4Home Computer

ACCESSORIES TO BE AVAILABLE:

32 Character PrinterRS232 Peripheral AdaptorDISK STORAGE/MEMORYMANY COMMAND MODULES

CALL OR WRITE FOR FULL PRODUCTINFORMATION AND LITERATURE

99/4 Computer s1150—

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SPEECH MODULE $149.95

(263 Words, available OCT/NOV)

COMMAND MODULES ...$20 to $60

99/4 DEALER INQUIRIES INVITED—CONTACT NEECO FOR INFORMATION

NEECO IS PLEASED TO ANNOUNCE THAT WE HAVE BEEN SELECTED AS ONE OF THE Tl 99/4 COMPUTERDISTRIBUTORS FOR THE NEW TEXAS INSTRUMENTS 99/4 HOME COMPUTER. OUR GOAL IS TO MAKE THE Tl99/4 COMPUTER, IN ADDITION TO OUR MANY OTHER PRODUCTS, AVAILABLE TO INDEPENDENT COMPUTERSTORES NATIONWIDE. 99/4 PRODUCT AVAILABILITY IS SEPTEMBER/OCT BUT IS ALWAYS SUBJECT TO TEXASINSTRUMENT'S 99/4 PRODUCT ALLOCATION.

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MASTERCHARGE OR VISA ACCEPTEDTELEX NUMBER 951021, NEECO

Circle 289 on inquiry card.

BYTE September 1979 159

Handy Pulser

Bob Chrisp

3428 Executive Av

Falls Church VA 22042

Figure 1: Schematic for the Handy Pulser.Switches SW4 and SW5 allow selection ofpositive or negative going pulses. SwitchSW2 is a momentary contact switchwhich allows single pulsing. All resistorsare .25 W and all resistances are measuredin ohms. All capacitor values are given inmicrofarads.

+ 5VA

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VAK-1 MOTHERBOARD

• Designed specifically for use with the AIM-65, SYM-1, and KIM-1 microcomputers

• Standard KIM-4* Bus

• Fully buffered Address and Data Bus

• Provides 8 expansion board slots

• Complete with rigid card-cage

• All IC's are socketed

• Provides separate jacks for one audio-cassette, TTY, and Power

• Completely assembled (except for card-cage)

We manufacture a complete line of high quality expansion boards. Use reader servicecard to be added to our mailing list, or U.S. residents send $1.00 (International send $3.00U.S.) for airmail delivery of our complete catalog.

PRICE: $129.00

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160 September 1979 © BYTE Publications Inc

Circle 325 on inquiry card.

Most of us at one time or anotherhave had the need for a TTL(transistor-transistor logic) pulsersource for troubleshooting or circuitdesign. Since most of us are not af-fluent enough to afford sophisticatedtest equipment we will usually kludgea TTL oscillator or pulser when theneed arises. However, the next timewe need our handy little circuit weend up searching our goody box onlyto find that we have used the parts inanother piece of equipment.

What I have tried to put together isan inexpensive oscillator thathopefully will stay in 1 piece and beready when needed. In an effort tokeep it simple and inexpensive I haveleft out some of the niceties that arefound in your more expensive com-mercial test gear: variable pulse level,variable offset, rise and fall time con-trol, double pulses, etc.

Design

Three integrated circuits form thebasis of the oscillator: a 555 timerconnected as an oscillator, a retrig-gerable oneshot and a hex driver.Potentiometers Rl and R2 in conjunc-tion with the capacitor selected byswitch SWl determine the operatingfrequency of the 555. I used poten-tiometers for both resistances so that Icould have control of the duty cycle.The equation for the operating fre-quency is given by:

f= 1.44

(R1 + 2(R2))C

The output of the 555 is connected toa 74122 retriggerable oneshot. Theuse of the oneshot allows independentcontrol of frequency with the 555 andindependent control of pulse widthwith the 74122. The combination ofthe 2 integrated circuits lets you trig-ger your oscilloscope from one edgeand the other edge triggers the 74122.The 7407 was included for drivecapability. SW3 allows for singlepulse operation and SW4 and SW5provide positive and negative syncand pulse outputs respectively.

Construction

The 3 integrated circuits weremounted on Micro Vectorbord usingwire wrap sockets. The pull upresistors were mounted on the same

board with wire wrap pins. The re-maining components were mountedon the front panel. I decided not to in-clude a power supply in this designbecause the pulser is always beingused with a breadboard which has itsown supply or it is being used on myprocessor. By using the supply ofwhatever I am working on I don'thave to run extra ground leads.

Variations

If you anticipate doing a lot ofwork where you must be synchro-nized to an external signal, then SW6could be replaced with a single-poletriple throw switch with the thirdposition being the output of a 7413Schmitt trigger. The input of theSchmitt trigger would be your exter-nal signal.

Utilization

There are 2 things to be carefulabout in the use of the Handy Pulser.One, there are certain combinationsof operating frequency and pulsewidth that will give you a constant 1or 0 output; two, make sure the delaybetween your oscilloscope sync andpulse output keeps you on the screen.Otherwise, you can be delayed rightoff the screen.

Specifications

With the values shown in figure 1the unit's specifications are:

• Pulse repetition frequency .05 Hzthru 400 kHz

• Pulse delay 2 /is thru 3 seconds

• Pulse width 2 (is thru 5 seconds

Final Comments

As I mentioned before, I decidednot to include a power supply in thisdesign but rather use the supply ofwhatever I am working on. One pro-blem that arises is that most manufac-turers do not provide convenientplaces to pick up the +5 V andground. Rather than install separateconnectors on each card, I installed a5 V regulator with convenient con-nectors on the mainframe of my com-puter. This has proven to be a greatasset. If nothing else, it is a handyplace to find ground since the frame isnot ground. I used an LM-309regulator with pin jacks and ter-minals.!

Circle 70 on inquiry card.

ANDSTUFF

Computer terminals, business systems,lab components ... they all need desksand enclosures. That's what we're allabout. Computer Furniture and Acces-sories offers a standard line of furnituresuitable for a wide variety of applica-tions. Handsome, rugged, economicalfurniture in all shapes, sizes and colors.Basic models shipped from stock indays, not months. And we're nice peopleto deal with. What more could youask for?

CF*A

Computer Furniture and

Accessories, Inc.

1441 West 132nd Street

Gardena, CA 90249

(213)327-7710

September 1979 © BYTE Publications Inc 161

TRS-80 SOLUTIONS!

BUSINESS

Appointment log by M. Kelleher. Perfect for theprofessional. Accepts name and address, meetingstart and endings, subject matter, derives elapsedtime. For Level II, 16K $9.95

Payroll by Stephen Hebbler. Comprehensive 24 pg.manual with step-by-step instructions included in thepackage. Prints W2 and 941 information. Disk -$59.95.

Mail List I by Michael Kelleher is the economy modelof disk-based mailing list programs. Uses a singledrive and handles up to 1400 names per disk, plusprovisions for sorting options. 16K, D $19.95.

| BUS-80 | |

I The Business Software People®

J Just about everything you need ... within 1 j

year, participants receive programming for I

i Inventory, Accounts Receivable, Accounts j

Payable and General Ledger systems, plus I

Payable and General Ledger systems, plus| Sales and Payroll. Complete documentation' and software on diskette, $200.00

i

ST 80 - Smart Terminal

Lance MicklusTurns your TRS-80 into a computer terminal.Features include CONTROL key, REPEATkey, ESC key, RUN key and a functioningBREAK key. Lets you list incoming data online printer. Reprogram RS-232-C switchesfrom keyboard, making baud rate changessimple. Level II, 16K $49.95ST80D

Lance MicklusContains extensions for disk drive systems toexchange files with a timesharing computeror another TRS-80. Can be customized fyredefining translation tables. Can transmitany type of TRS-80 ASCII file, also binaryfiles. A practical, full-feature terminalprogram of professional quality. For 32K disksystems $79.95.

Mail List II by BUS-80. Complete mail list system fordual disk. Enter, update, merge, sort, and printmailing labels. D, 32K $99.95

Small Business Bookkeeping by Roger W. Robitaille,is based on the Dome Bookkeeping Journal, sold foryears in stationery and discount outlets. Level II, 4Kwith ($22.00) or without ($15.00) Dome journal.

Small Business Bookkeeping For Disk by MillerMicrocomputer Services and Roger W. Robitaille, Sr.Extended version. 32K Disk. With journal $31.95;without journal $24.95.

Inventory S by Roger W. Robitaille, Sr. 240 stockitems can be contained using the full 6 data areas and2 pieces of alpha information. Level II,16K $25.00

Inventory II.2 Disk based program allows forcreation, maintenance and review of over 2,000 itemsper clean diskette. Operates under Disk BASIC, DOS2.1 with minimum memory allocation. D, $59.95

Electric Pencil by Michael Shrayer. A wordprocessing system. Insertions, additions, deletionsand corrections made more easily than with aneditor's pencil. Perfect text printouts. Level II, 16K,$100.00. 32K Disk, $150.00

Accounts Receivable II by S. Hebbler. Does yourbilling, provides running balance, tracks overdueaccounts, custom message printing option, muchMORE. Requires 32K 2-disk system $79.95

General Ledger I by M. Kelleher. Establishes,defines, deletes and sorts up to 400 accounts. Up to200 entries per session. For small-to-mediumbusinesses not requiring double entry books. A com-prehensive, flexible accounting system. Requires32K disk. $79.95.

Inventory System 2.3 by M. Kelleher. One of smallbusiness management's most difficult problemsbrought under control. Keep current on priceincreases, shrinkage, low stock, profit margins.Program can handle up to 1,000 items per datadiskette. Improved version, lower price. Withdocumentation $99.95, 32K 2-disk.

Text-80 by Frank Rowlett. Fully-documented textprocessing system for disk. Create, edit, move,delete, insert, change, print words or lines. D, 32K$59.95

8080-Z80 Conversion by M. Kelleher. Permits you toenter 8080 codings and returns the Z80 equivalent. LII, 16K $15.00

Basic Statistics by Steve Reisser. Pearson product-movement correlation coefficient, chi-square, FisherT-test, sample analysis of variance, Z-scores andstandard scores, with a random number generatorbuilt in to simulate data. L II, 16K $20.00

WANTEDUSED TRS-80 EQUIPMENT!We buy and sell used equipmentSample Prices:

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Step up to the amazing Exidy Sorcerer.Features high-resolution graphics, 64 x 30character video, monitor and fast floating-point BASIC in ROM, user-definable charac-ter set, and the best keyboard of any micro.Sorcerer power can be yours for $995 [8KRAM], $1145 [16K], and $150 per 16Kadditional. A wide range of system andapplication soltware is also available.

!

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I NEWDOS + (

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ACTION GAMES

Slalom by Denslo Hamlin. Choose between Slalom,Giant Slalom and Downhill. Level II. 16K $7.95Air Raid by Small System Software. High speedmachine language program with large and smallaircraft flying at different altitudes. Ground-basedmissile launcher aimed and fired from keyboard.Planes explode when hit, cause damage to nearbyaircraft. Score tallied for hits or misses. Level I or II,4K $14.95.

All Star Baseball by David Bohike, Level II, 16K$7.95

Batter Up by David Bohike. Level II, 16K $5.95X-Wing Fighter II by Chris Freund. Piloting anX-wing fighter, you're out to destroy the Death Star!A new, improved version of an exciting spacefavorite. Level II, 16K. $9.95

Ten Pin by Frank Rowlette. A game of coordination,the scoring is true to the rules of the sport. Level II,16K $7.95

Taipan by Art Canfil. Sail the China seas, dodgingpirates and cutthroats, to make your fortune tradingin arms and opium. Level II, 16K. $9.95.Balloon Race by Dean Powell. High above theAtlantic, your balloon must be cleverly maneuveredwith the prevailing winds to reach Paris. Level II,16K, $9.95.

|

ADVENTURES

Scott Adams

Feel as if you're manipulating HAL from 2001when you play these machine languagegames. Hardly any rules, finding out is partof the fun. Two adventures on 32K disk,$24.95. Tape - choose from Land Adventure,Pirate's Cove, Mission Impossible, TheCount, and Voodoo Castle - $14.95 each.

DOG STAR ADVENTURE| Lance Micklus

j You're trapped aboard an enemy battlestar

[ ... can you find the gold, rescue the princess,

I discover the plans and safely escape? Level

j II, 16K $9.95.

J

Journey To The Center Ot The Earth by GregHassett. Excellent introduction to the excitement ofADVENTURE. Written in BASIC for ease ofunderstanding, yet fast and fun!!. Level II, 16K tape$7.95.

Amazin' Mazes by Robert Wallace. Ever -changingmaze situation. Level II, 16K $7.95

Kamikaze by Russell Starkey. Command your shipagainst attacking suicide planes. Machine languagegraphics make this fast and fun! L II, 16K $7.95

Space Battles by Level IV. Assume the role ofGalactic mercenary, roaming the universe in searchof enemy aliens and the bounty you reap fromdestroying their ships! Danger, thrills, fast action —and financial headaches as welI! Features three levelsof play, fast, machine language graphics, real-timeinput, Level II, 16KTapeor32K Disk. Tape-$14.95;Disk -$19.95.

MISCELLANEOUS

Diskettes Dysan 104/1 Box of five, $24.95 + $1.00

shipping. Verbatim, box of ten, $34.95 + $1.00

shipping/handling.

Z80 Instruction Handbook by Scelbi Publ. $4.95

+ $1.00 shipping/handling.

The BASIC Handbook by Dr. David A. Lien $14.95 +$1.00 shipping/handling.

Percom Disk Drives. Single or dual, for TRS-80's.Reliable, high quality, priced $100 lower thancomparable units! Single drive-$399.00; Dual Drive-$799.00; Cable (required) - $29.95.

Floppy Armour Protective envelopes for shippingfloppy disks, of high-density, ultra-lightweightpolymer. 5-pack, $4.95 + $1.00 shipping/handling

f

16K MEMORY KITSIthaca Audio8 tested, guaranteed 16K RAM's, amazinglow price - $99.95.

162 BYTE September 1979

Circle 313 on inquiry card.

Electronics Assistant by John Adamson. Profession-ally written. Will draw sample schematics and helpyou design active and passive low-, band-, andhigh-pass filters, coils, attenuator networks, andthree types of impedance-matching networks.Extensive graphics, one key selection routine. LevelII, 16K -$9.95.

SIMULATIONS

3-D Tic Tac Toe by Scott Adams. Three skill levels -author warns you to practice before tacklingcomputer's third skill level. I or II, 16K $7.95

Star Trek III.3 by Lance Micklus. One of the mostadvanced Star Trek games ever written. Level II, 16K$14.95.

End Zone by Roger W. Robitaille, Sr. Authenticfootball simulation, right down to the 2-minutewarning. Level I or II, 16K $7.95

Cribbage by Roger W. Robitaille, Sr. You versus thecomputer cribbage played by standard rules. Level Ior II, 16K, $7.95.

'Round the Horn by Rev. George Blank. You're thecaptain of a clipper ship racing from New York to SanFrancisco. Level II, 16K $9.95

Concentration by Lance Micklus. One of the mostpopular television games. Level I or II, 16K $7.95

Safari by David Bohlke. You're in the running for afilm contract at a major Hollywood studio. To qualify,you must photograph the most wild animals in theirnatural habitat. Level II, 16K $7.95.

Pork Barrel by Rev. George Blank. Places you in theshoes of an aspiring Congressman. Level II, 16K$9.95

Backgammon by Scott Adams. Level II, 16K $7.95

Chess Companion by M. Kelleher. Combines chessclock features with ability to record your moves whileaction is fast and furious. Level II, 16K $7.95

Sargon Chess by Dan & Kathe Spracklen. Winner ofthe 1978 San Jose Microcomputer Chess Tourna-ment. Level II, 16K $19.95

Mastermind II.2 by Lance Micklus. Lets you and thecomputer take turns making and breaking codesLevel II, 16K$7.95

PERSONAL

RPN Calculator by Russell Starkey. A self-document-ing calculator program. Uses Reverse Polish Notationwith4-level stack, 100 memories, scientific functions.Level II, 16K $9.95

Home Financial Management by M. Kelleher. Turnsyour computer into a personal financial advisor. LevelII, 16K$9.95

Tarot by Frank B. Rowlett, Jr. Probably the bestfuture-gazing type program ever written. Try it -you'll like it! Level I or II, 16K $9.95

Ham Radio by M. Kelleher. Amateur Frequency Allo-cations, ID Timer, Q-signal File, Amateur LogRoutine, Propogation Forecasting. L II, 16K $9.95.Special Disk-enhanced version, 32K $24.95

Educator Assistant by Steve Reisser. Five programsof value to educators. Compute percentage,individual student averages, class averages, standardtest scores, final grades. L II, 16K $9.95 D, $14.95Typing Tutor by 80 US. A set of programs designed toteach you touch typing. Takes you from basics tohigh-speed drill, with quizzes and grades. Progress atyour own pace, and have fun mastering anenormously useful skill. Level II, 16K - $19.95.

T|«

TR5-80 Software Exchange

1*605*675.5144

17 BRIAR CLIFF DRIVE MILFORD, NEW HAMPSHIRE 03055

Personal Finance by Lance Micklus. 33 differentbudgets can be easily adapted by user to fit hisindividual needs. A 2-part program, entry andsearch. Level II, 16K $9.95

Advanced Personal Finance by Lance Micklus. Sameas above with advanced analysis routine. SupportsDisk Files D, 32K $24.95.

UTILITIES

KVP Extender by Lance Micklus. Corrects keyboardbounce, upper case lock, permits use as a terminal,screen printing. On tape ($24.95) or disk ($29.95)

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BYTE September 1979 163

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Languages Fcpum

Come From...continued

R Lawrence Clark, 30303 Avenida de Calma,Rancho Palo Verdes CA 90274

While I applaud Mr Bass' attempts to improve theBASIC language ("Languages Forum," April 1979 BYTE,page 238), he has completely missed the point of theCOMEFROM statement. The primary goal of theCOMEFROM is to eliminate GOTOs, which Dijkstraand many other advocates of structured programmingconsider harmful. If the statement can also be used totrace back execution during debugging, that is an unex-pected bonus.

I provided a detailed description of the semantics of theCOMEFROM in "A Linguistic Contribution to GOTO-less Programming" (Datamation, December 1973). Brief-ly, the statement:

destination COMEFROM source

is equivalent to the conventional:

source GOTO destination

where both source and destination are line numbers.

The original article describes additional variants,which in BASIC would appear as the following:

IF condition COMEFROM source

and:

ON variable COMEFROM sourcel,source2, ... , sourceN

Because of the COMEFROM's potential for improvingprogramming accuracy and readability, I feel it is impor-tant to clarify its proper usage. ■

Languages Forum is a feature which is intended as an interactivedialog about the design and implementation of languages for per-sonal computing. Statements and opinions submitted to this forumcan be on any subject relevant to its purpose of fostering discussionand communication among BYTE readers on the subject oflanguages. We ask that all correspondents supply their full namesand addresses to be printed with their commentaries. We also askthat correspondents supply their telephone numbers, which will notbe printed.

164 September 1979 © BYTE Publications Inc

More on MultipleConditions

Scott Lawrence, 201B Lehman N SUCP,Potsdam NY 13676

David Faught's letter titled "On Expressing Multiple Con-ditions" in the December 1978 BYTE Languages Forum,page 176, does a good job of illustrating the need for alanguage construct to deal with actions based on multipleconditions. I, too, found the means available in BASIC,FORTRAN, and COBOL (I am not yet familiar with Pascal)somewhat lacking.

This need is met, however, in PL/I by the SELECT group.The basic syntax of this construct is shown in listing 1.

Listing i.

SELECT (expression);

WHEN (expression-1, expression-2) action-1 ;WHEN (expression-3 action-2;OTHERWISE action-3;END;

When the SELECT statement is executed, the expression inparentheses is evaluated and the value is saved. The expres-sions in the WHEN statements are then evaluated one at atime in the order in which they appear. As each one is evalu-ated, its value is compared to the saved value. If a value isfound that matches the saved value, the action specified bythat WHEN statement is executed and no further expressionsare evaluated. If none of the values match, the action speci-fied by the OTHERWISE statement is executed.

The actions after the WHEN and OTHERWISE statementsmay be a simple statement, a compound such as IF . . .THEN . . . , a group of statements within a DO or BEGINblock, a GO TO statement, a null statement, a subroutinecall, or even another SELECT group. After the action hasbeen performed, control passes to the first statement afterthe END (unless the action specifies otherwise, of course).

If the expression in the SELECT statement is omitted, theexpressions in the WHEN statements are treated as logicalstatements and evaluated as a bit string. If any bit in thestring is 1 (signifying true), the action is performed. (A=Bwould be evaluated as a 1 bit if A and B contained the samevalue.) Listing 2 shows an example of such a SELECT group.

Listing 2.

SELECT;

WHEN (A<B) CALL LESSTHN;WHEN (A=B) CALL EQUAL;OTHERWISE CALL GRTRTHN;END;

It is also possible to omit the OTHERWISE statement. Ifno WHEN statement is selected and there is no OTHERWISEstatement, an error interrupt is caused. This is useful forcatching critical data that has somehow gone out of the ac-ceptable range.

I think this construct meets the needs which Mr Faughtexpressed, and is easier to implement than the alternativehe suggests."

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September 1979 © BYTE Publications Inc 165

Data Abstractions andProgram Correctness

Earl E McCoy, U-157, University of ConnecticutStorrs CT 06268

One of the most interesting and informative aspects ofBYTE magazine is the dialogue about programminglanguages found in the Languages Forums and Letterscolumn. Many times these discussions are initiated by anarticle which included an example program in a par-ticular language. The ongoing debate about the strengthsand weaknesses of various programming languages ismost informative and useful to those people who knowonly one language well.

The recent article concerning queuing theory, "Queu-ing Theory Part Is Queue Representation" (April 1979BYTE, page 132), by Len Gorney provides a good vehiclefor discussion. My comments are not to be taken ascriticism of author Gorney, but as comentary concerningBASIC as compared to a contemporary language such asPascal. It is important for programmers to understandthat the difference between BASIC (and FORTRAN) andPascal is not just one of degree, but one of type as well.

One of the most important and fundamental conceptsin modern software engineering practice is that of data-abstraction. The data-abstraction has great influence

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upon program correctness. A data-abstraction is definedas a data-structure and the set of operations that may belegally performed upon it. An example in the queuingtheory context is the data-abstraction queue, for which adata-structure must exist to store its contents, and forwhich 5 operations are allowed: initialization, insertion,deletion, overflow, and underflow. The semantic mean-ing of these operations is also defined, but will not berepeated here so as to avoid duplication of the Gorneyarticle.

How is a queue to be implemented in a programminglanguage? It would be simple if a programming languageincluded a data-structure of type queue but, to myknowledge, none do. In general there exists an infinitenumber of data-structures of potential interest, and nolanguage could include them all. Instead, any particularlanguage usually includes only a small set of data-struc-tures such as reals, integers, and characters; and arrays,records, and files of these structures. No insurmountableproblem exists, however, because a data-structure of in-terest can usually be constructed from these existingprimitive data-structures. Thus one may construct aqueue data-structure by using an array and 2 integers(head and tail pointers).

Notice that the implementation of a queue data-struc-ture in the manner just described does not result in thedata-abstraction of a queue: the program manipulatingthe array and the pointers is in no way restricted to the 5legal queue operations. It is this lack of operation restric-tion that can result in program incorrectness, particularlyin large programs undergoing maintenance. For example,because the data-structure is global(ie: exposed to the en-tire program) a "fix" for a particular problem may resultin a new problem elsewhere within the program.

Pascal addresses the data-abstraction concept directlyby allowing the declaration of more than just variables(as opposed to other languages). This includes constantvariables, which may never be the target of an assign-ment operation, and more importantly, the declarationof novel data types. For example in Pascal we mightdefine waitingline to be a variable of type queue by thefollowing:

var waitingline : queue;

Note that we might want more than 1 variable of typequeue. This is allowed, as are the arrays of queues and soon. The contents stored within the queue may be items oftype integer:

var items : integer;

However, they might be persons:

var items : persons;

Note that integer is a defined data-structure in Pascal, butthat queue and persons are not. Before discussing this fur-ther, a comment on what advantage this brings the pro-grammer is appropriate.

Recall the definition of a data-abstraction: a data-structure and the legal operations upon it. By writingprocedures and functions for the legal operations upon adata-structure we are, in effect, implementing a data-

166 September 1979 © BYTE Publications Inc Circle 366 on inquiry card.

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abstraction. For example, in the queuing context, we maydefine procedures for initialization, insertion and dele-tion, and functions for overflow and underflow. Programcorrectness is enhanced if these are programmed correctlybecause queues can then be manipulated only in legalways. Remember that queues will be passed to thesesubroutines — not the underlying array data-structure.

Back to the problem of implementing the user declareddata-structure types in Pascal. This is accomplished bydeclaring data-structures at a level above variables:

type persons = . . .

queue = . . .

Here the dots indicate the data-structures necessary toimplement the type in Pascal. For example, in the queu-ing theory context, we might have:

type queue = record

head, tail : 0 . . maxlength;full, empty : boolean;

contents : array [0 . . maxlength] of integer;end;

Here maxlength is a constant declared earlier in the pro-gram which indicates the legal subrange of the integervariables head and tail (used as pointers); full and emptyare logical variables indicating the status of the queue;and contents is an array storing the contents of the queue.In this case the queue is storing integers, but it need not— it could just as well be persons:

contents: array [0 . . maxlength} of persons;

Of course, the meaning of persons would have to bedeclared earlier within the type statement for this to belegal Pascal.

After the user declared data-structures are defined,variables of these types can be declared as follows:

var waitingline : array [1 . . 3] of queue;teller 1: queue;

These 4 queues are restricted to the definition of queue asshown above. If necessary, we might declare more than 1type of queue (ie: storing a different type of contents) ifthe problem context makes that appropriate.

Listing 1 shows Pascal procedures and functions im-plementing the 5 legal queue operations. Note that theparameters are a and b. A change of the b type declara-tion is all that is necessary to make these programsworkable for a different type of contents. An importantpoint: there is no need to initialize the contents of thequeue to a particular value and use this value to decidehow to manipulate the pointers, as is implied by theGorney article. In fact, by doing so a programmer is sow-ing the seeds for future disasters. If Mr Gorney's queue isever exposed to a value of -9, the program may fail.Clearly, making correct operation dependant upon theavoidance of certain potentially legal entries into the datastructure is not good programming practice.

At this time it is informative to step through the BASIClanguage equivalents in the Gorney article using sometrial data. The complexity of program execution flow

168 September 1979 © BYTE Publications Inc

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makes mental execution exhausting and error-prone —which is exactly the point: BASIC programs are not assimple as they seem.

The data-abstraction is complete when a Pascal pro-gram uses the 5 legal operations upon its variables of typequeue. Examples are:

initialize (tellerl);

if not fullq (tellerl)

then insert (teller, items);

repeat

delete (tellerl, items);write (items)until emptyq (tellerl);

Note that the programmer has the responsibility to testfor overflow or underflow before inserting or deletingitems from the queue. This is true even though the respec-tive procedures do nothing for these operationalmistakes.

Listing 1: This simple Pascal program defines the data typequeue and then describes the 5 legal operations on that datatype.

procedure initialize (var a : queue);begin

a.head : = 0;a. tail: = 0;a.full := false;a.empty : = true;end; {of initialize}procedure insert (var a : queue; b : integer);beginwith a doif not fullthen begin

empty : = false;contents [tail] : = b;

tail:= (tail + 1) MOD (maxlength + 1);if tail = headthen full: = true;end;end; {of insert]procedure delete (var a ; queue; var b : integer);beginwith a doif not emptythen beginfull: = false;b := contents [ head ];head : = (head + 1) MOD maxlength + 1);if head = tailthen empfy := true;end;end; {of delete}function fullq (a : queue ) : boolean;begin

if a.full

then fullq : = trueelse fullq : = false;end; {of fullq}function emptyq (a : queue ): boolean;begin

if a.empty

then emptyq := trueelse emptyq := false;end; {of emptyqs}

170 September 1979 © BYTE Publications Inc Circle 394 on inquiry card.

Circle 205 on inquiry card.

Listing 2: The data stack can also be defined in a Pascal pro-gram. It is left as an exercise to the reader to translate this pro-gram into BASIC or FORTRAN and compare the understand-ability of the 2 programs.

type stack = record

top : 1.. maxlength;full, empty : boolean;

contents : array [1 . . maxlength] of integer;end;procedure initialize (Var a : stack );begin

a.full := false;a.empty : = true;a. top : = 1;end; {ofinitialize)procedure push (var a ; stack; b : integer);beginwith a doif not fullthen beginempty : - false;contents [top] : = b;if top < > maxlengththen top : = top + 1else full: = true;end;end; {ofpush]procedure pop (var a ; stack; var b : integer ): boolean;beginwith a doif not emptythen beginfull ; = false;b : = contentsftop];if topo 1then fop ; = top - 1else empty ;= true;end;end; {ofpop)function fullstk ( a : stack ): boolean;begin

if a.fullthen fullstk := trueelse fullstk ;= false;end; {of fullstk)function emptystk ( a : stack ): boolean;begin

if a.emptythen emptystk : = trueelse emptystk := false;end; {of emptystk)

In summary, the data-abstraction is an important con-cept that greatly enhances program correctness. ThePascal programming language includes this concept;BASIC does not. My point again: the simplicity ofBASIC is a red herring — it encourages sloppy program-ming and error-prone programs. A contemporary lan-guage like Pascal is explicity designed to encourage error-free program development, therefore it is worth learningand using. One more point: experienced Pascal program-mers know that the language includes pointers as a datatype so the queue data-abstraction could be implementedeven more easily than shown here. This particularmethod was chosen to correspond to the approach takenby the Gorney article.

Just as a queue is an FIFO (first in, first out) data-abstraction, a stack is an LIFO (last in, first out) data-abstraction. Listing 2 shows a Pascal type declarationand the subroutines that are necessary to implement thelegal operations upon a stack. These are included in thehope that readers may implement this data-abstraction inBASIC or FORTRAN and then compare for themselvesthe relative merits of these 2 languages to Pascal.■

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Speaking of regular boards, we offer assembled /tested models and boardsqualified under our high-reliability Certified System Component (CSC) pro-gram (200 hour burn-in, immediate replacement in event of failure within 1 yearof invoice date). Refer to chart below for pricing.

SI

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Name

Storage

Buss

Configuration

Unkit

Assm

CSC

Econoram HA

8KX8

S-100

2-4K blocks

$149

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Econoram IV

16KX8

S-100

1-16K

$269

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Econoram VI

12KX8

H8

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$200

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n/a

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16KX8

S-100

2-4K, 1-8K

$279

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$398

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n/a

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n/a

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Econoram XII-16 16K X 8 S-100 2 ind. banks** $329 $419 $519

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* 'Econoram XII-16 and -24 have 2 independent banks addressable on 8K boundaries; Econoram XIII has 2 independent banks addressable on 16K boundaries.

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ACTIVE TERMINATOR KIT $34.50

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*\

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P3ul

MAGAZINE COMPARISON

(2 years)

Monthly Averages

6800 Articles

KB

7.8

TOTALPAGES-

BYTE CC DOBB'S

6.4 2.7 2.2 19.1 ea. mo.

Average cost for all four each month: $5.88

(Based on advertised 1-year subscription price}

68' cost per month: $1 21

That's Right! Much. Much More

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BYTE September 1979 175

Circle 236 on inquiry card.

IMMEDIATEDELIVERY

Domestic & Export

DEC LSI -11COMPONENTS

A full and completeline with softwaresupport available.

mini ComputerSuppliers, Inc.

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Cover Craft Dust Covers are available fromyour local computer retailer * * Q(- *q qRor contact Cover Craft. 9O.yO-9y.rO

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Event Cueoe

In order fo gain optimumcoverage of your organi-zation's computer con-ferences, seminars, work-shops, courses, etc, noticeshould reach our office atleast three months in advanceof the date of the event. En-tries should be sent to: EventQueue, BYTE Publications,70 Main St, PeterboroughNH 03458. Each month wepublish the current contentsof the queue for the month ofthe cover date and the twofollowing calendar months.Thus a given event may ap-pear as many as three times inthis section if it is sent to usfar enough in advance.

SEPTEMBER 1979

September 4-6International Conferenceand Exhibition on Engineer-ing Software, University ofSouthampton, England. Theaim of this conference is toprovide a forum for thepresentation and discussionof recent advances inengineering software and topresent a state-of-the-art inthis field. The exhibitionheld in conjunction with theconference will cover allsoftware products, servicesand equipment related toengineering software. Con-tact Dr R Adey, Engsoft, 6Cranbury PI, SouthamptonS02 0LG, ENGLAND.

September 4-7Compcon Fall '79, CapitalHilton Hotel, WashingtonDC. This 18th Institute ofElectronic and ElectricalEngineers (IEEE) ComputerSociety International con-ference will present the latestdevelopments in micropro-cessor architecture, supportsoftware, operating systems,and peripheral devices. Con-tact IEEE Computer Society,

POB 639, Silver Spring MD20901.

September 5-8Info/Asia, Ryutsu Center,Tokyo. This exposition willbe devoted to informationmanagement, computers,word processing, and ad-vanced business equipment.The exposition will be ac-companied by a 4 day con-ference. Contact Clapp andPoliak Inc, 245 Park Ave,New York NY 10017.

September 82nd Annual MicrocomputerFaire, Cullen College ofEngineering, University ofHouston. 70 exhibitors areexpected at this computerfair. Contact Dr John LHubisz, Division NaturalScience and Math, Collegeof the Mainland, Texas CityTX 77590.

September 12-13Gateway Computer andOffice Systems Expo, Chase-Park Plaza Hotel, St LouisMO. This 2 day event willinclude a program of ex-hibits and conferences whichwill be open to data proces-ing and business profession-als. Contact The ConferenceCo, 60 Austin St, NewtonMA 02160.

September 18-20Wescon/79, St FrancisHotel, San Francisco CA.Contact Electronic Conven-tions Inc, 999 N SepulvedaBlvd, El Segundo CA 90245.

September 24-26Minicomputers andDistributed Processing, NewYork NY. This 3 dayseminar will examine theuses, economics, programm-ing and implementation ofmini computers. ContactThe University of Chicago,Center for ContinuingEducation, 1307 60th St,Chicago IL 60637.

176 September 1979 © BYTE Publications Inc Circle 84 on inquiry card.

September 25DP User DocumentationWorkshop, Kansas CityMO. The workshop willfocus on how to write DPuser manuals. Emphasis ison analysis of specific userneeds; planning and outlin-ing; and effective writing,illustration and packaging ofdocumentation. ContactProgressive CommunicationsInc, The Alamo/310, 128 STejon St, Colorado SpringsCO 80903.

September 25-27Mini/Micro Conference andExposition, ConventionCenter, Anaheim CA. Con-tact Robert D Rankin,Managing Director, Mini/-Micro Conference and Ex-position, 5528 E La PalmaAve, Suite 1A, Anaheim CA92807.

September 25-27WPOE '79, San Jose Con-venter Center, San Jose CA.This show will be dedicatedto word processing andoffice/business equipment,services and materials. Com-plementing the exhibit willbe a 3 day executive con-ference program that focuseson emerging technologiesand their applications in theoffice. Contact Cartlidgeand Associates Inc, 491Macara Ave, Suite 1014,Sunnyvale CA 94086.

September 25-28The 3rd Annual Data EntryManagement Conference,

Hyatt Regency, NewOrleans LA. This conferencewill feature a full scheduleof speakers, workshops,panels and vendor exhibitsto assist the data entry pro-fessional. Contact Data En-try Management Associa-tion, POB 3231, StamfordCT 06905.

September 26-29MIMI '79, Queen ElizabethHotel, Montreal, Canada.This symposium is intendedas a forum for the presen-tation and discussion of re-cent advances in mini andmicrocomputers and theirapplications. Special em-

phasis will be given to thetheme of the conference"The Evolving Role of Minisand Micros WithinDistributed Processing."Contact The Secretary,MIMI '79 Montreal, POB2481, Anaheim CA 92804.

September 28-30Northeast Personal andBusiness Computer Show,

Hynes Auditorium, BostonMA. Displays and exhibitswill showcase microcom-puters and small computersystems of interest tobusinesspeople, hobbyists,professionals, etc. Lecturesand seminars will be pre-sented for all categories andlevels of enthusiasts, in-cluding introductory classesfor novices. Contact North-east Exposition, POB 678,Brookline MA 02197.

OCTOBER 1979

October 1-32nd Annual Symposium onSmall Systems, Hilton Inn,Dallas TX. The symposiumwill consist of a blend ofpaper and panel discussionswith major emphasis onmicrocomputer applications.Both hardware and softwaretopics presenting state-of-the-art and state-of-the-industry aspects will be in-cluded. Contact GeraldKane, Southern MethodistUniversity, Dallas TX 75222.

October 2-4NEPCON Central '79,O'Hare Exposition Center,Rosemont IL. This 10thannual exhibition and con-ference of electronic andmicroelectronic packagingand production equipmentwill feature displays of elec-tronic and microelectronicmaterials, hardware, tools,supplies and test instru-ments. Contact Industrialand Scientific ConferenceManagement Inc, 222 WAdams St, Chicago IL60606.

October 14-17International Data Proces-sing Conference and

Circle 87 on inquiry card.

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The CY-480 replaces bulky, expensive, dedicated controllers.

This small, single LSI package offers a 5 x 7 dot matrix character generator, fullupper and lower case ASCII 96-character font, and a 48-character (expandable bydaisy-chaining) internal line buffer storage. Standard features include a 10,12 or 16characters/inch variable character density command, and horizontal and verticalindependently expanded print command. The CY-480 provides graphic capabilityand includes a "flip-print" operating mode for 180° viewing, and ready lines providefull asynchronous communications with handshaking.

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From S-lOO toIEEE-488

P&T-488+ S-100 computer = Intelligencefor your Instrumentation System

The P&T-488 permits an S-100 computer to operate as a talker,listener, or controller on the IEEE-488 instrumentation bus forless than half the cost of calculator-based systems. Softwarepackages which give access to the 488 bus from high level lan-guages such as BASIC are available for CP/M, North Star DOS/BASIC, and Cromemco CDOS. Or "roll your own" systemwith the custom system package of assembly language drivers.P&T-488, assembled and tested, + anysoftware package: $400 (domestic USA)

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Circle 308 on inquiry card. September 1979 © BYTE Publications Inc 177

Circle 288 on inquiry card.

■I

OAE'S new PP-2708/16PROM Programmer is theonly programmer with allthese features:

• Converts a PROM memorysocket to a table top pro-grammer: No complex inter-facing to wire —just plug itinto a 2708 memory socket*

• A short subroutine sendsdata over the address linesto program the PROM

• Programs 2 PROMS for lessthan the cost of a personal-ity module. (2708s and TMS2716s)

• Connect 2 or more in paral-lel — super for productionprogramming

• Complete with DC to DCswitching invertor and 10

^*Pat s Pending

turn cermet trimmers (forprecision pulse width andamplitude alignment)

• All packaged in a handsomealuminum case

PP-2708/16 . .A & T$325.

PP-2716 (Programs Intel's2716) A & T $295.

OAE

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Main/Frames 0. $2

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INTEGRAND

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Business Exposition, Townand Country Hotel, SanDiego CA. Contact DataProcessing ManagementAssociation, 505 BusseHighway, Park Ridge IL60068.

October 15-186th Information Manage-ment Exposition and Con-ference, New York Coli-seum, New York NY. Con-tact Clapp and Poliak Inc,245 Park Ave, New YorkNY 10017.

October 15-19CPEUG 79, San Diego CA.This is the 15th meeting ofthe Computer PerformanceEvaluation Users Groupsponsored by the NationalBureau of Standards. Con-tact Judith G Abilock, TheMITRE Corp, Metrek Div,1820 Dolley Madison Blvd,McLean VA 22102.

October 16-18Understanding and UsingComputer Graphics, Wash-ington DC. This course is forpeople who are now using,or making decisions aboutusing computer graphics andits role in their organization.It will describe computergraphics, explain what hard-ware and software systemsare available and give costand performance com-parisons. Contact Frost andSullivan, 106 Fulton St, NewYork NY 10038.

October 20-214th Annual TidewaterHamfest-Computer Show-Flea Market, Cultural andConvention Center, NorfolkVA. Contact TRC, POB7101, Portsmouth VA23707.

October 21-23New York State Associationfor Educational DataSystems Annual Conference,

Granit Hotel, KerhonksenNY. The theme of this con-ference is "InstructionalComputing - Hardware/-Sof tware /Courseware."Contact Mary E Heagney,9201 Shore Rd, BrooklynNY 11209.

October 22-24The Association of Com-puter Programmers andAnalysts 9th Annual Con-ference, Washington DC.The general theme of thisconference is "PreparingToday for Tomorrow's NewTechnologies." Suppliers ofsoftware packages and com-puter services have been in-vited to describe and presenttheir products in a series ofstructured presentations.Other sessions will covertrends in system technologyand new methodologies forsharpening the professionalskills of both systemsanalysts and programmers.Contact DBD Systems Inc,1500 N Beauregard St, Alex-andria VA 22311.

October 22-24Computers in AerospaceConference II, Hyatt HouseHotel, Los Angeles CA. Theconference theme, "Com-puter Technology for Spaceand Aeronautical Systems inthe 80s," will be carried outby a series of panels, invitedpresentations, and con-tributed papers which willbring computer systemtechnologists together withspecialists in the applicationof embedded computers inspace and aeronautics. Con-tact American Institute ofAeronautics and Astro-nautics, 1290 Ave of theAmericas, New York NY10019.

October 22-25ISA/79, O'Hare ExpositionCenter, Chicago IL. Theconference theme, "Instru-mentation for Energy Alter-natives," will emphasize cur-rent practices in instrumen-tation design and implemen-tation. Contact InstrumentSociety of America, 400Stanwix St, Pittsburgh PA15222.

October 22-26Pascal Programming forMini and Microcomputers,

Ramada Inn, Woburn MA.Sponsored by thePolytechnic Institute of NewYork and the Institute forAdvanced ProfessionalStudies, this workshop will

178 September 1979 © BYTE Publications Inc Circle 177 on inquiry card.

Circle 303 on inquiry card.

include application ex-amples, lectures, informalsessions with the instructor,as well as individual andgroup programming ses-sions. Contact ProfessorDonald D French, Institutefor Advanced ProfessionalStudies, One Gateway Ctr,Newton MA 02158.

October 28-30The 10th North AmericanComputer Chess Champion-ship, Detroit Plaza, DetroitMichigan. Sponsored by theAssociation for ComputingMachinery, this is a 4 roundSwiss style tournament withthe 1st 2 rounds to beplayed on October 28th (1PM and 7:30 PM), the 3rdon October 29th (7:30 PM)and the final round on Tues-day, October 30th (7:30PM). Contact MonroeNewborn, McGill Univer-sity, School of ComputerScience, 805 Sherbrooke StW, Montreal PQ,CANADA H3A 2K6.

NOVEMBER 1979

October 29 - November 2Applied Interactive Com-puter Graphics, Universityof Maryland, College ParkMD. This course is designedto cover the most importantfacets of graphics that arenecessary to develop generalgraphic applications.Systems considerations arestressed, including con-figuration selection criteriaand the pros and cons ofoff-the-shelf software. Themost important factors andtechniques are described forhardware, software andgeometric modeling. ContactUCLA Extension, 10995 LeConte Ave, Los Angeles CA90024.

October 30 - November 1Interface West, AnaheimConvention Center,Anaheim CA. This 3rdannual West Coast smallcomputer and officeautomation systems con-ference and exposition willfeature over 100 companyexhibits and 60 conference

sessions covering a varietyof data processing, wordprocessing, data communica-tions, mangement hardware,software and service topics.Contact the InterfaceGroup, 160 Speen St, Fram-ingham MA 01701.

November 5-8Electronics ProductionEngineering Show, KosamiExhibition Center, SeoulKorea. This international in-dustrial exposition will bedevoted to the needs ofmanufacturers of electronicproducts in Korea. ContactExpoconsul, Clapp andPoliak International SalesDiv, 420 Lexington Ave,New York NY 10017.

November 6-8Midcon/79 Show and Con-vention. O'Hare ExpositionCenter and Hyatt RegencyO'Hare, Chicago IL. ContactElectronic Conventions Inc,999 N Sepulveda Blvd, ElSegundo CA 90245.

November 6-8Institute of Electronic andElectrical Engineers (IEEE)3rd International Conferenceon Computer Software andApplications, The PalmerHouse, Chicago IL. ContactIEEE Computer Society,POB 639, Silver Spring MD20901.

November 6-83rs Digital Avionics SystemsConference, Fort Worth TX.This conference will probethe expectations andchallenges of the digitalrevolution in avionicssystems. Contact John CRuth, Technical ProgramChairman, POB 12628, FortWorth TX 76116.

November 12-14Computer Cryptography,

The George WashingtonUniversity, Washington DC.The objective of this courseis to provide each partici-pant with a workingknowledge of the use ofcryptography in computerapplications. ContactContinuing Education,George Washington Univer-sity, Washington DC 20052. ■

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Circle 293 on inquiry card. September 1979 © BYTE Publications Inc 179

THE ORIGINAL'

•PersonalC Computing

Plan Now to attendthe best PersonalComputing show ever,

Friday, Saturday, SundayOctober 5-6-7thPhiladelphia Civic Center

Philadelphia, Pa.

PC 79

®

Don't be confused — Other shows are copying us butthey cannot equal us. We are the Original PersonalComputing Show. Now in our Fourth Year.

FEATURING:

Major Exhibits

from the

Leading Companies

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Personal Computing College

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Free Seminars by the

Industry's Leading Speakers

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Major Emphasis

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Software Exhibits

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2nd Annual

Computer Music Festival

Bigger! Better!

•

Antique

Computing Devices

on Display

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See All the LatestHardware

•

Business Systems

andBusiness Software

For more information and aFree subscription to our "PERSONALCOMPUTING" newspaper, sendyour name and address to:

PERSONAL COMPUTING 79

Rt. 1, Box 242 . Mays Landing, N.J. 08330 . 609/653-1188

Industry TRADE SHOW on October 4thFor exhibiting information please call or write.

180 BYTE September 1979

"THE ORIGINAL"

> PersonalC Computing

EXHIBIT DATES & TIMES

REGISTRATION

at the door includes admission to all seminars.

■ 3 days — October 5, 6, 7 $10.00

■ Single day $5.00

DEALER DAY

Thursday, October 4also includes October 5, 6, 7 $15.00

For Dealers, Purchasing Agents, Industry-Reps, Industry Officials only.

2nd annual

PERSONAL COMPUTER

MUSIC FESTIVAL

Saturday evening, October 6, 1979.

Harrison Auditorium, Univ. of Pennsylvania,which is 1 block from the Philadelphia CivicCenter. Doors open at 6:30 P.M.

Featuring; Live demonstrations and perform-ances by leading computer musicians.

A stereo record from last year's music festivalwill be on sale at the show.

Daytime seminars and demonstrations at thePhiladelphia Civic Center all day on Saturday,Oct. 6th, during the Personal Computing Show.800 Tickets will be on sale Friday and Saturdayfrom P.A.C.S. at The Philadelphia Civic Centerduring the Personal Computing show and atHarrison Auditorium.

The Personal Computer Music Festival is spon-sored by the Philadelphia Area ComputerSociety. For more information contact themat: P.O. Box 1954, Philadelphia, PA 19105.

FRIDAY

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REMEMBER: Monday, Oct. 8th, is Columbus Day, <^which gives an extra day to travel home.

BYTE September 1979 181

The AMSAT-GOLEM-80

Joe Kasser

11532 Stewart Ln

Silver Spring MD 20904

The AMSAT-GOLEM-80 Micro-computer Project provides a meansfor a group or club to put together anS-100 bus microcomputer in arelatively inexpensive manner. It is amodular system of hardware andsoftware that can be built as a stand-alone system or superimposed on anexisting S-100 machine. It is designedto be expandable and affordable.Many people who belong to micro-computer clubs, or who are learningabout microprocessors, would like toown a microcomputer. However,theymay not want to make the initial in-vestment of $500 to $1500 for thebasic hardware. The AMSAT-GOLEM-80 is designed to be built instages, as finances allow. Each stageof the AMSAT-GOLEM-80 is func-tionally complete and can verify theperformance of the next stage. It iscapable of incorporating any S-100card, contains a powerful debuggingsoftware package (AMS-80 version5.7), and the I/O (input/output) in-terface handlers for your system. It isdesigned to be flexible and easilycustomized to fit your requirements.This is recommended as a group pro-ject for 3 reasons: 1) to take advan-tage of bulk discounts in the purchaseof hardware; 2) knowledgeable indiv-iduals are available to help others;and 3) test equipment can be shared.

The order of construction is log-ical. Sections can be built and used tocheck out subsequent sections. Thus,a sequence of construction could beto build the cabinet and front-panelpower supply, motherboard, consoleI/O card, programmable read-onlymemory card, programmable mem-

Photo 1: The AMSAT-GOLEM-80 prototype computer.

ory card (1), and processor card. Atthis level the basic AMS-80 programcan be executed. The order of con-struction can be varied depending onthe individual constructor'spreference. The group can also buildseparate parts, put them together toget 1 machine working, then have themembers build their own parts attheir own pace.

This technique of construction maynot be the cheapest in the long run,but it is in the short run. It also allowsnearly instant results, since themachine is doing something almost assoon as construction is begun. This ispsychologically important, consider-ing the amount of money involved. Itis difficult to decide which system isthe cheapest in the long run. Buildinga microcomputer can be an open-ended drain on your finances becauseyou will probably keep adding newmemory and I/O peripherals.

System Basics—Hardware

The hardware is standard S-100bus circuit cards, but any Z80/8080processor card, memory card, or I/Ocard may be used. Circuitry is avail-able for a hardware front panel. Thisoperates by putting the processor inthe "hold" state and then taking overcontrol of the bus lines. Memory andI/O ports can be exercised andchecked out. A single-step feature isoffered, as is jump start or boot startto a software monitor program. Sev-eral unique circuits are available foramateur radio use (eg: satellitetracking).

Software

The AMSAT-GOLEM-80 project isdesigned for active experimenters. Itis expected that some machine-language programming will be per-formed on each machine. Thus, a fulland expandable operating debug or

182 September 1979 © BYTE Publications lnc

monitor package is available. Thisprogram AMS-80 is a much improvedand expanded version of AMS-80which was first published in theSeptember 1976 issue of BYTE. Apartfrom the usual memory and registerexamine/change features, it incor-porates direct I/O operations, adisassembler mode, and keyboard-interruptable console operations. Alist of the commands is shown in table1. All I/O drivers are containedwithin AMS-80, devices can be con-figured in software, and all I/Odevices are accessed via a jump table.All utility routines used within themonitor are also available via jumptables, as shown in table 2. The hex-adecimal base address is F000 and theI/O driver section of the jump table iscompatible with the Technical DesignLaboratory's Z80 monitor.

Also available is a floating-pointmath pack (Intel software library ver-sion relocated), a floating-point inter-preter; a macro-organized pseudohigh-level language using a floating-point stack, and operating throughthe math pack and various other soft-ware, including radio teletypewriter(RTTY) reading programs which aremainly suited for amateur radio ap-plications. Patches for commerciallyavailable software (but not the actualsoftware) are also available. Thesepatches include Processor Tech-nology 5 K BASIC and North Star'sdisk operating system.

The Power Supply

The power supply is 1 of the 2single-point failure points in thesystem (the other is the processor). Ifit fails, the system is down. Thus, itshould be overrated, cooled, andhave a little spare capacity on hand.It should be capable of at least thefollowing performance: 8 to 10 V at10 to 20 A, 16 to 18 V and —16 to—18 V at 2 A. The supply can beunregulated because each S-100 cardcarries voltage regulators as required.Use plenty of fuses; put 1 in the ACline and 1 in each of the DC supplies,as shown in figure 1. If you wish toadd crowbar circuits, over-voltageprotection, or shut-down circuits,that's fine.

The Cabinet

The cabinet is the part of the

A

B

C

D

E

F

G

H

I I

J

K

L

M

N

0

P

Q

R

S

T

U

V

w

XY

z

PRINT (MEMORY) IN ASCII

*

CONFIGURE I/O (INPUT/OUTPUT) DEVICEDISPLAY (MEMORY) IN HEXADECIMALWRITE END OF FILE RECORD TO TAPEFILL (MEMORY) WITH CONSTANTGO TO LOCATION AND EXECUTEHEXADECIMAL MATH (SUM AND DIFFERENCES)NPUT FROM PORT TO CONSOLE

PRINT (MEMORY) IN ASSEMBLY LANGUAGEMOVE BLOCK OF (MEMORY)PUNCH 6 INS LEADER TAPEOUTPUT TO PORT FROM CONSOLESCAN TAPE

*

READ TAPE

EXAMINE/CHANGE (MEMORY)PUT HEADER ON TAPEDISPLAY I/O CONFIGURATION

VERIFY PROGRAMMABLE MEMORY BLOCK WORKSWRITE TO TAPEEXAMINE/CHANGE (REGISTERS)

'Not assigned as yet.

Table 1: AMS-80 version command list, version 5.7. Details of the operation of thecommands are given in the description of AMS-80.

Interactive ComputerGraphics Software*

For Microsoft and DEC* Fortran

DEVIATIONS

'<vSt< »> J''i "'{( *^> t i,n!', to sncra ■mentft! n high speec

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standard Fortran IV, making it porta-ble to all computers, including miniand mi- ms.

The entire set of over 20 subpro-grams. >r a CRT ter-minal and a Diablo 1620 printer, sellsfor $4 !ier devicmay I

*Tr<irjem< *.rtf totp.

above graphs arc examples, of the

P. The top graph was made on a X-Y-Z

refreshed display, the bottom graph

made on a Diablo* 1620 printer."

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COMi 5

Circle 53 on inquiry card.

September 1979 © BYTE Publications Inc 183

Circle 202 on inquiry card.

THE WORLD'S FIRSTALL SOLID STATE

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INTRODUCING THE TASA MODEL 55ASCII KEYBOARD.

Imagine. A full capability, 128 positionkeyboard without a single moving part.Simply touch its surface and sophisticatedelectronics instantaneously transmit informa-tion to your computer.

Imagine further. This state-of-the-artkeyboard provides a TTL output that is fullyencoded, verified, processed, and de-bounced on a 6-position, dual-sided cardedge connector. Ready to plug in andoperate.

IF THE PRICE SOUNDS UNBELIEVABLE,REMEMBER WHAT SINGLE-CHIP TECHNOLOGYDID FOR THE CALCULATOR.

The secret of the TASA keyboard'spowerful performance and low price is fullyintegrated single-chip circuitry. Becausethere are no mechanical keys or flex switchesto move up and down, all the electronics canbe completely sealed inside the tough poly-carbonate case. This makes the TASA key-board virtually indestructible and immune tospills and rough handling.

And since there are no moving parts,your TASA keyboard should have the sametrouble-free life expectancy as a silicon chip.HERE ARE A FEW STATE-OF-THE-ART FEATURES:

• Full 8-bit ASCII output and continuousstrobe.

• Low power: 18 V DC, 35 mA, built-inregulator.

• Parallel output: active pull-down, directTTL compatible (one load), open collectortype.

• Dimensions: 15"Lx6.25"Wx0.325" thin.

• Easy hook-up to any system, includingthe Apple computer.

ALSO AVAILABLE:

The Model 16-A, a 16-key alphanumericfully encoded, solid state 4x4 keyboard foruse as a companion to the Model 55, or as astand-alone data entry unit.TRY THE TASA KEYBOARD FOR 10 DAYS.

Enclose payment with the order form.Connect the TASA keyboard to your com-puter and use it for 10 days. If you don'tagree that this keyboard is worth many timesthe price, simply return it to us. Your moneywill be refunded in full.

r

PLEASE SEND THE FOLLOWING:

□ TASA Model 55ASCII keyboard.. $75.

□ TASA Model 55 with stand and con-nector $93.

D TASA Model 16-A keyboard $55.

Add $4. for shipping and handling.

Enclosed is my check or M.O. for $

or Mastercharge/VISA #

expires

name

ADDRESS _

CITY STATE ZIP

KML

■ MiHKfTi*r*:

P.O. BOX 1237 LOS ALTOS, CA 94022

AMS80:

ORG

OFOOOH

<R>

JMP

CUSTOM

START OF SOFTWARE

JMP

CONSI

CONSOLE TO <A>

JMP

RDR

READER TO <A>

JMP

CONSO

<C> TO CONSOLE (ASCII)

JMP

PUNCH

<C> TO PUNCH (ASCII)

JMP

LIST

<C> TO LIST (ASCII)

JMP

CSTS

TEST CONSOLE STATUS

JMP

IOCHK

DETERMINE I/O (INPUT/OUTPUT) CONFIGURATION

JMP

IOSET

SET I/O CONFIGURATION

JMP

MEMCK

FIND TOP OF USER AREA (PROGRAMMABLEMEMORY)

JMP

RESTART

BREAKPOINT ENTRYENTRY POINTS

JMP

START

REENTER BMS-80

JMP

BEGIN

BYPASS CUSTOMIZING AREA

CONSOLE ROUTINES (INDIVIDUAL)

JMP

CHIN ;

CONSOLE INPUT AND ECHO

JMP

CONSA ;

<A> TO CONSOLE

JMP

TCSTS ;

GOTO MON IF CONSOLE INTRPT

JMP

TCRET ;

OUTPUT CR/LF

JMP

AOUT

<A> TO CONSOLE

JMP

THXB

OUTPUT <A> (HEXADECIMAL-2 DIGITS)

JMP

THXW

OUTPUT <H/L> (HEXADECIMAL-4 DIGITS)

JMP

MSG

OUTPUT TEXT

JMP

PCHK

TEST FOR NULL INPUT CHAR

JMP

CONSB

<B> TO CONSOLE (ASCII)PUNCH ROUTINES

JMP

PHXB

<A> TO PUNCH (HEXADECIMAL)

JMP

LEAD

PUNCH 6 INS LEADER TAPE

JMP

PCRET

OUTPUT CR/LF TO PUNCH

JMP

PHXW

OUTPUT H/L TO PUNCH

JMP

POB

<B> TO PUNCH (ASCII)LIST ROUTINES

JMP

LHXW

OUTPUT H/L TO LIST

JMP

LHXB

<A> TO LIST (HEXADECIMAL)

JMP

LCRET

OUTPUT CR/LF TO LIST

JMP

LOB

<B> TO LIST (ASCII)UTILITY ROUTINES

JMP

CONV

CONVERT HEXADECIMAL TO ASCII

JMP

NIBBLE

CONVERT ASCII TO HEXADECIMAL

JMP

DONE

TEST FOR COMPLETION

JMP

TIMER

DELAY

JMP

SDEHL

HL-DE

JMP

LOCMB

LOCATE CONTROL BYTE IN PROGRAMMABLEMEMORY BLOCK

JMP

IRST

RESET INTERRUPTS

JMP

BACON

BAUDOT TO ASCII CONVERSION

JMP

ASCBD

ASCII TO BAUDOT CONVERSION

JMP

$

SPACE FOR PATCHES

JMP

$

Table 2: AMS-80 interface jump table. The individual routines are discussed in detail inthe description of AMS-80.

system that your friends will see andadmire. It should look presentable.The number of switches and lights onthe front panel has been the subject ofnumerous debates. Those which arenecessary are a power on/off switch,a boot switch, and a reset switch. Ifyou are doing a lot of I/O program-ming (common in amateur radioapplications), an output port and aninput port (sense switches) are useful.Status lights, control bus lights, anddata and address bus lights/switchesare optional. One full hardware testerpanel should be built within eachgroup if no known working system orother method for troubleshooting thehardware is available. The prototype

shown in the photograph contains thefull hardware tester panel circuit andis built separately from the powersupply. This has the advantage ofportability.

The Front Panel Interface

This card interfaces the front panelswitches and displays to the S-100bus. It is used when first building thesystem to check out the operation ofthe individual cards. Once AMS-80 isrunning, its usefulness is diminisheduntil a hardware failure occurs thatleaves the system up, but inhibits theprocessor from working properly (eg:a bus buffer or data-bit failing). Thecontrols on the front panel will then

184

September 1979 © BYTE Publications Inc

Ihe

Data

Duo*

FromDTC

&*

w

rifi

N?

0" MS*

>6>

<$r

.A®"

*V»

«^ ^'

I

■ ^— ^W i^^' ^m *T Sw^WrTSPTBFw*^W"^** USE "Pf* t*% '^n '^"^RtlSK'" iSK'^lfc''wK'^Bfc iK

^mims*^^. > ijj^efiTOB&nagn ',^^ygs»ggt<a^^

tf

*

What you see is what you get.

Our Model 382 Data Terminal lets youmanipulate your data-or-words-in-process on an eye-level CRT beforeyou commit printer time to it. The 382is a truly elegant terminal that integratesvideo display with a letter qualityprinter to save you time, paper andconsumable supplies.

On the screen you'll see 24 lines of 80characters, with separate field attributecharacters. And in memory, ready toscroll up or down into view, are four fullpages (96-lines). You can even storeeight full pages if you don't need thefield attribute symbols.

Distributor informationavailable.

Circle 97 on inquiry card.

The Data Daisy, too.

The DTC 382 is also the first system youcan buy that has the full ASCII 96-character metal print wheel, our

Data Daisy. Crisp clarity, long-livedmetal, and a full 96-character set! Justwhat dp and communications peoplehave been asking for. Purchase or fullmaintenance lease pricing is available.Please contact your local dealer or DTCfor complete pricing details.

\\UHti.

Get one and start enjoying:

True proportional spacing

Speeds up to 55 char/sec.

Fast-throughput, automatic

reverse typing

Automatic underlining

Shadow printing

1200 baud (burst mode) for printer

9600 baud for video display

RS-232C

Worldwide fast service

Write, TWX or call for additionalinformation: Data Terminals &Communications, 590 DivisionStreet, Campbell, CA 95008.(408) 378-1112. TWX: (910) 590-2436.Toll free number: (1) 800-538-9779

BYTE September 1979 185

m*©**

o

GND

(Z>

v.

10-12VAC

RECTIFIER

Fl 20A

-of"Vx, L>

; 100,000^ f

) +BV

-o

RECTIFIER

F2 2A

—<r\ja—

; 3000/iF

'^77

3000/iF

F3 2A-cPoo—

D,

Figure 1: Typical S-100 computer power supply.

allow the problem to be located in aswift manner. When in the run mode,the address lights also indicate thelocation of the software that is beingcurrently executed. This is useful indetermining exactly where your pro-gram is hung up during debugging.

The Memory

Any S-100 bus programmableread-only memory and program-mable memory card can be used.However, if you are using a card thatplaces a limit on the time period thatit can be addressed continuously (ie:

NOW, FROM MOUNTAIN HARDWARE.

THE 100,000 DAY CLOCK.

■ ■.■■,■ <vv

Put your S-100 Computeron the clock.

A real time clock could double theutility of your computer. Time eventsin 100/nS increments for up to 100,000days (over 273 years). Program eventsfor the same period with real timeinterrupts that permit pre-programmed activities to takeplace...without derailing on-goingprograms. Maintain a log of computerusage. Call up lists or appointments.Time and date printouts. Time events. Anon-board battery keeps the clock running inthe event of power outage.

Mountain Hardware also offers a complete lineof peripheral products for many fine computers

23

Available at your dealer's. Now.

Mountain Hardware, Inc.

300 Harvey West Blvd.Santa Cruz, CA 95060 (408) 429-8600

one using dynamic programmablememories), you will have to modifythe select signals from the front-panelinterface card to convert these signalsin a pulsed mode (gate the clock intothe control signals). Shop around fora good group buy. AMS-80 requiresat least 4 K bytes of programmableread-only memory. You may want toput additional software in program-mable read-only memory.

The 8080 can access 64 K bytes ofmemory. Since most personal sys-tems do not contain a full 64 K bytesof memory, and 8080 software is non-relocatable by virtue of its absolutemode-addressing capability, severalmanufacturers have put out softwaremodules at fixed allocations. TheRadio Amateur Satellite Corporation(AMSAT) has developed a memorymap for software, thus making alluser written software compatible.Using the expandable idea, basic soft-ware can be executed in minimalmemory systems. The memoryassignment map is shown in table 3.

The main user memory area is up-ward expandable from location 0. Nomatter how much memory is avail-able, software will run if written forlow locations. Hexadecimal 0100 is agood starting location so that the in-terrupt service area is not overwrittenby your customized software.

As home systems are assembled,they tend to fall into 1 of 2 distinctconfigurations. There is the floppydisk system, having much program-mable memory and a minimalamount of programmable read-onlymemory in which programs arestored on disks and down-loaded intouser memory for execution. Thesecond type is the eraseable read-onlymemory (EROM) based system.EROMs and EROM cards arerelatively inexpensive. Programs canbe stored in EROM and executed viaAMS-80. This type of system con-tains less user memory than thefloppy disk system. Since EROMcards come in 16 K-byte blocks, it isdesirable that such a block be incor-porated in the AMSAT-GOLEM-80system. This allows for inter-changeability and redundancy. Foradded flexibility, the chosen cardshould have user memory coexistencecapability. Thus, a group system canbe put together out of both types ofconfiguration, with minimal con-flicts. This block is located betweenhexadecimal 8000 and BFFF.

186 September 1979 © BYTE Publications Inc

Circle 258 on inquiry card.

The *15,995 System

Are you tired of inadequate floppy systems and overpriced mini-computers? BASIC TIME offers an affordable Minicomputer Systemwith 10MB hard disk storage, printer w/stand and CRT. All completewith desk enclosure.

Since the introduction of our System B-100 in June ofthis year, we have had an overwhelming responsefrom you, the minicomputer system buyer. Thereason for this response is, when it comes down toprice, you can't find a much better value nowadays ina Small Business Computer System than what we areoffering.

Our Central Processor is a 16-bit, single board unitwith 65K bytes of memory, using a 2901 microcom-puter to emulate the Data General Nova instruction set.

we offer 10MB of hard disk storage on two disks,one fixed and the other removable, to allow forbacking up the system.

The operating system comes complete with BusinessBasic integrated with a sophisticated file manage-ment system. It is easily programmable by first timeusers and it supports editor and all facilities/utilitiesto develop business application packages. We alsoinclude a variety of subroutines to make develop-ment easier.

The system comes with a full function video displayterminal that has a standard typewriter keyboard anda 10 key numeric pad. The display screen will display1920 characters (24 lines of 80 characters).

We have an optional printer that prints letterquality type if your needs are in that area, included

Circle 14 on inquiry card.

with that option, at no additional cost, is a wordprocessing package.

We include a Ceneral Business software packagethat consists of: general ledger, accounts payable,accounts receivable, payroll and inventory control.We provide complete software documentation toallow the user to modify it to fit his own needs. Thereis no charge for the software.

The B-100 is upgradeable for users that requiremulti-user and muli-tasking capabilities. However, weplan to introduce our System B-200 in November.This system will be capable of multi-user and multi-tasking and it will handle up to four CRT's and printersin any combination.

we have complete Dealer and OEM packages whichinclude: pricing information and Dealer/OEM agreements.

basic

tirn

1215 E. El Segundo BoulevardEl Segundo, California 90245213/322-4435

BYTE September 1979 187

FFFF

FCOO

FOOO

E800DFFF

DOOO

CCOOBFFF

8000

010000100000

AMS-80 Custom Area,

I/O (input/output) handlers, including VDB-4 software

AMS-80 Standard Area

Floppy Disk I/O and Bootstrap Loader

4 K-Byte, Programmable-Memory Area for Buffers, etc.

Video-Display Memory Area

16 K-Byte, Programmable Read-Only-Memory Area (preferablymaskable)

User Programmable-Memory-Program Area

Interrupt Service Area, Interfaces, etc.

AMS-80 Programmable-Memory Links

Table 3: Memory assignment map for the AMS-80.

The block can be used to containprograms that execute in those loca-tions, or copies of programs that ex-ecute when moved to programmablememory locations in low memory.This is ideal for programs that need tobe executed in user memory, or forstoring programs as a backup to thefloppy disk unit in case it is notavailable at a particular time or loca-tion, such as a demonstration at acomputerfest.

Processor Technology's SOL soft-ware is written to reside at hex-adecimal C000. It can be placed inthat area if desired. The video displayprogrammable memory is located atCCOO. This makes it compatible withProcessor Technology and SSM.

A programmable memory area is

assigned at hexadecimal DOOO. Thisallows the stack to be located outsideof the main user area. The bufferareas for cassette I/O can be locatedin this area, as can any program-mable memory-dependent softwarethat is required for your system.AMS-80 is designed to automaticallylocate the stack in an area of usermemory above the video block. Italso skips this area when a user pro-gram asks for the top of usermemory. If no such block exists andthe video area is used, AMS-80 willhave to be customized to avoid thevideo programmable memory areaduring initialization.

The Processor

Any S-100 bus processor card can

be used. Different cards have dif-ferent features. Some have jump startor bootstrap capability, some haveinterrupt ports, and some have both.Some are available already built, andothers as kits or blank boards.Choose one that suits the needs ofyour group.

Input/Output

You will need (and AMS-80 is con-figured for) 4 classes of I/O (in-put/output) devices, a console, ahigh-speed data-input device(reader), a high-speed data-outputdevice (punch), and a high-speed,ASCII output device (list). TheAMS-80 software allows 4 physicaldevices to be assigned to eachcategory of I/O device. Theassignments are in software and maybe changed under program control.Software is provided for a video-display board (Cybercom) as well asa Teletype interface. Audio tape ischosen for off-line program and datastorage. A floppy disk drive can beadded at will.

All I/O operations are performedon a single character basis, either inor out. Kansas City Standard toneshave been chosen as the audio re-cording standard. There is, however,1 basic difference between the use ofpaper and audio tape. Paper tape canbe stopped between punches or reads,but audio tape cannot be efficientlystopped. Thus, the audio cassetteroutines contain "blocking" softwarethat stores the individual charactersin a user memory area (preferablybetween hexadecimal DOOO and E800,as shown in table 3). This blockingsoftware is transparent to AMS-80.Software is provided for all I/O tothe console or terminal, the punch,reader, or list devices. The routinesare located within AMS-80 and arecalled indirectly via a jump table asshown in table 2. Routines are pro-vided to ouput ASCII data fromeither the B or C register, allowingexisting commercial software to bepatched to operate via AMS-80 withminimal changes. Routines are alsoprovided to output the contents of theaccumulator (8 bits) or the H/Lregister pair (16 bits) in hexadecimalcode. Character input routines arealso provided. Most of the routinesare used within AMS-80.

There are 2 reserved I/O portswithin the system. These are front

188 September 1979 © BYTE Publications Inc

It

it's on the dou

INTRODUCING — LOUMAR MANAGEMENT SYSTEMS SOFTWARE

a

programs to give you a comprehensive package for business management

The Loumar General Accounting System is a versatile, fully integrated software package designed for small and medium sizedbusinesses. It is also suitable for CPA's and bookkeeping service films.

The complete software system is composed of four main modules: GENERAL LEDGER, ACCOUNTS RECEIVABLE, ACCOUNTSPAYABLE AND PAYROLL. Each module may be used separately or in combination with any other module. Supplied on disk asruntime modules. Source not available.

All software is written in CBASIC II and utilizes the powerful CP/M operating system.General system features include:

Automatic posting to general journal • Strict error detection • Report production on demand • Consistent operating procedures •User oriented. No previous computer knowledge required • Designed by accounting professionals • Comprehensive, well pre-sented reports and manuals • Single or multiple client capabilities.

HARDWARE SPECIFICATIONS PAYROLL: Up to 500 employees - $550.

The end user's microcomputer must satisfy the following require ACCOUNTS RECEIVABLE: Up to 1000 customers and 1000 monthly

transactions — $550ACCOUNTS PAYABLE: Up to 1000 vendors and 1300 monthly

transactions - $400GENERAL LEDGER: Up to 200 accounts with 2000 entries -

$450

merits:48k RAM

Dual floppy disk system

Printer with tractor. All printing is done in 80 col. formatCRT with at least a 64 character by 16 line displayCP/M and CBASIC II

Write lor our brochure — Dealerships still availableContact: Distributor

MISSION CONTROL • 2008 WILSHIRE BOULEVARD, SANTA MONICA, CA 90403 • (213) 829-5137

Circle 237 on inquiry card. BYTE September 1979 189

Pin#

Signal

1

Chassis Ground

2

Data From Terminal To Computer

3

Data From Computer To Terminal

4

Control Line #1

5

Status Line #1

7

Signal Return (Ground)

8

Control Line #2

10

+ 18 V Supply

13

-18 V Supply

17

20 mA Current Loop ( + ), Terminal To Computer

20

Status Line #2

23

20 mA Current Loop ( +), Computer To Terminal

24

20 mA Current Loop (-), Terminal To Computer

25

20 mA Current Loop (-), Computer To Terminal

Note: This is a modified RS-232 Interface. Signal Levels are as follows:

Mark (Logic

1) = -3 V to -12 V, Space (Logic 0) = +5 V to +12 V.

Table 4: Connections to the serial port interface connector.

1

Chassis Ground

2

Data Port 1 Status Bit

3

Data Port 1 Control Bit

4

Data Port 1 Bit 0 (LSB)

5

Data Port 1 Bit 1

6

Signal Return

7

Ground

8

N/C

9

+ 8 V Raw Power

10

Data Port 2 Bit 6

11

Data Port 2 Bit 7

12

Data Port 2 Status Bit

12

Data Port 2 Control Bit

14

Data Port 1 Bit 2

15

Data Port 1 Bit 3

16

Data Port 1 Bit 4

17

Data Port 1 Bit 5

18

Data Port 1 Bit 6

19

Data Port 1 Bit 7

20

Data Port 2 Bit 0

21

Data Port 2 Bit 1

22

Data Port 2 Bit 2

23

Data Port 2 Bit 3

24

Data Port 2 Bit 4

25

Data Port 2 Bit 5

NOTE: All voltage levels are transistor-transistor logic compatible. The Data Lines are com-

patible to the MITS convention. Port 1 is configured as an input port and port 2 as an

ou

tput port if bidirectional I/O port integrated circuits (such as 8255s) are not used.

Table 5: Connections to the parallel port interface connector.

panel (FF) and interrupt control port(FE). The front-panel address is usedfor both displays and switches. FFwas chosen because of the simplehardware needed to decode it (1NAND gate), while FE was built intothe processor card utilized in the pro-totype.

Some standardization of the hard-ware is desirable in a group project.This allows 1 person to check outanother person's hardware. It alsoallows different members of thegroup to interconnect their equip-ment for large demonstrations.

Interfaces come in 2 types: serialand parallel. The following stan-dards, which are slightly modifiedversions of existing ones, are sug-gested for the AMSAT-GOLEM-80Project.

Audio Signals

All audio signals from the com-puter or interface boxes to and fromcassette recorders are via phonoplugs/sockets. The actual connectorson the tape recorder may be anythingfrom miniature phone to DIN-typeconnectors.

RF/Video Signals

BNC-type connectors should beused to carry video to and frommonitors. The BNC connector issmall, quick to connect and discon-nect, and readily available world-wide.

Digital Signals

Digital signals come in 2 types:serial and parallel. Both types ofinterfaces should use 25-pin EIA-type

connectors. The chassis connector onthe computer will be female; thechassis connector on the remotedevice is male. Power can be feddown the cable from the computer tothe remote device via the I/O cable.Having a female connection on thehot lead reduces the probability ofshort circuits. They can also be joinedtogether to make larger ones, withoutthe need for special adaptors. Theserial connector assignments arebased on the RS-232 interface. Thepin assignments are shown in table 4.The parallel connector carries 1 inputand 1 output port (8 bits each), plus 1pair of handshake signals. The signalpins are compatible to the MITSrecommended ones. Power andground are fed down the cables, thusthe recommendation for fuses in the 3DC voltage lines. The parallel port in-terfaces are transistor-transistor logic(TTL) level, the serial port RS-232voltage levels (mark = negative,space = positive). The pin assign-ments are shown in table 5.

AMS-80

AMS-80 is a full, software-de-bugging program. It also contains thesystem I/O drivers and utilityroutines accessible via a jump table.The jump table approach is utilized sothat user programs written using theutility routines within AMS-80 willnot require reassembling, should asubsequent version of AMS-80 bereleased. The version that waspreviously published (September1976 BYTE) has undergone extensivemodifications and has been relocatedto the block of memory between hex-adecimal F000 and FF00. This allowsmany existing programs written forlow, user memory area (such as MITSBASIC) to be run through the I/Odrivers within AMS-80. It is thuspossible to run a program in BASICand have the ouput appear on the lineprinter (list device) or the console atwill. The standard capacity existingin AMS-80 is shown in table 1.

System Expansion

The modular design of theAMSAT-GOLEM-80 system allowsfor operability at all stages of con-struction, once the initial stage isreached. Since a great deal of moneyis being spent, it would be encourag-ing to see it perform as soon as possi-ble. The initial stage, apart from theprocessor power supply and bus,

190 September 1979 © BYTE Publications Inc

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BYTE September 1979 191

Circle 54 on inquiry card.

ControlSystem

Software

lection of software for anafyzintrol systems. The set includ«quency domain methods such asBode and Root Locus algorithms, andmodern start* variable methods.

These programs will calculate thedata for a given system, and then pro-duce a tabulated printed output, agraphical display on a printer, or bothThe programs include both the analy-sis subprograms and the printer plot-ter subprogram.

• Bode Algorithm CS-B $100.

• Root Locus Algorithm CS-R $100.

• Time Response ......CS T $100.

All of the above packages will run on a8080 or Z80f — based CP/M* system.^Trademark of ZHog trademark of CHgttal

Research

COMPCO is a software and hardwaresystems development house locatedIn the Midwest. COMPCO has avariety of software products, andperforms custom and contractprogramming.

COMPCO is a distributor of ALTiComputer systems and also sellsGeneral Robotics LSI-11* systems^Trademark of Digital Equipment Corp.

wompco

8705 North Port Washington RoadMilwaukee, Wis. 53217 414/351-3404

COMPUTER SPECIALISTS

Punch

P = 3P = 2

P=1

Audio Cassette

P = Console

Reader

R = 3R = 2

R=1

Audio Cassette

R = 0

Console

List

L = 3

L = 2

Baudot device (model 15)

L=1

Teletype Port

L = 0

Console

Console

C = 3

C = 2

Baudot Device (model 15)

C=1

Video Display Board/Keyboard

c = o

Teletype Port

Video Di;

>play Board

V = 0

Page With Line Foldover

V=1

Page Without Line Foldover

V = 2

Scroll With Line Foldover

V = 3

Scroll Without Line Foldover

Table 6: AMS-80 I/O (input/output) allocations.

comprises 4 K bytes of programmableread-only memory of user memory,and a terminal device. With thisamount of hardware, you can runAMS-80, enter programs in memoryin hexadecimal code via AMS-80, andlearn a little about software. The ad-dition of some off-line memory, suchas audio or paper-tape devices,allows you to run programs which re-quire up to 4 K bytes of memory.Such programs include Tiny BASIC,orbital calculations for amateursatellite locations, and variousamateur radio programs. If you havea radio teletypewriter terminal unit(RTTY-TU), you can even tune yourshortwave radio in to commercial oramateur Teletype stations, anddisplay their transmissions on yourterminal.

If you get a modem interface and asecond terminal, or use a videodisplay/keyboard combination and aserial port/modem, you can make the

basic system into a remote terminalfor a large machine timesharing ser-vice, and access the computer at workfrom your home. Add another 4 or 8K bytes of user memory, and you canrun text editors, assemblers, or an 8 KBASIC interpreter. This opens a newdimension in computing. You canplay Star Trek, and run educationand business software and advancedamateur radio programs, such as con-tests. Put 16 K bytes of user memoryin your system and you can get afloppy disk unit for an added dimen-sion in computing.

Off-Line Data Storage

Off-line storage is storage for pro-grams and data that is external to the64 K bytes of accessible memory. Itusually consists of audio tape, floppydisks, or paper tape. Floppy diskstorage usually comes with anoperating system and will not bediscussed here. AMS-80 contains

192 September 1979 <S BYTE Publications Inc

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Circle 286 on inquiry card.

170-099BYTE September 1979 193

routines to store and read softwarefrom paper tape. Data is stored in In-tel hexadecimal format. Paper tape,although common in professionalcircles, is not cheap, and the readersand punches are expensive. However,inexpensive hand operated readers doexist, so paper tape is a convenientand easily mailable form of programstorage (for chort programs).

Paper tapes can be stopped undersoftware control. Thus, when BASICis reading and interpreting a pro-gram, it can stop the tape momen-tarily to process the line of sourcecode. Audio cassettes cannot be stop-ped in such a manner. Other pro-grams, such as Assemblers or Editors,also have requirements for occasionalinputs and outputs. Thus, AMS-80contains buffer cassette-driver soft-ware to enable the main program tothink that it is reading or writingcharacters on an incremental basis.Data is stored on tape in blocks of 256characters. There is no format assuch; the format is set by the mainprogram because in this system theaudio cassette is treated as if it ispaper tape. This means that by using

the Intel hexadecimal format andcassette buffer-driver routines inAMS-80, any paper-tape, cassette, orfloppy disk system can read or writetapes and convert to and from theformat needed for a particularoperating system. A title command isput into AMS-80 to allow headings tobe written on hexadecimal codeblocks of tape so that they can beidentified.

Since even a 15-minute cassettetape can hold a lot of software, acommand is provided within AMS-80to allow a tape to be scanned and aprogram found. The command trans-fers data from the reader to the punchdevice. It may be used to copy tapesor, if the console is assigned as thepunch, it may be used to scan tapesand locate particular blocks.

The number of data bytes in ablock is 256. Each block is precededand followed by a mark tone. Thisallows the tape to be stopped andstarted. The data is read to or writtenfrom the tape at 300 bps.

If the system has error detection,error-detection bytes are put on thetape. For example, the Intel hex-

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adecimal format checks each line ofcode for a read error. Each line asprinted on the console is a block initself. The data, address, and errordetection bytes are output to thepaper-tape punch. These bytes will becollected by the cassette buffer soft-ware which, when full, will write 256bytes on the audio tape. Whenreading that block back, it will readthe entire block into a buffer. The In-tel hexadecimal format reader thengets the data on a character-by-character basis from the buffer, andchecks for errors.

The cassette storage medium isdesigned to be a paper-tape equiva-lent for information exchange. It isnot designed to be part of anoperating system, although anAMSAT flexible operating systemmay be available in the near future.

Operating Systems

Cassette and disk operatingsystems are currently available.These can be patched to operatethrough the AMS-80 I/O (input/out-put) drivers and hence improve themby allowing assignable I/O devices.AMS-80 is a paper-tape operatingsystem in which the file storage andsorting is done by the operator.

The advantages of software con-figured I/O can be seen in the follow-ing circumstances: BASIC is designedto operate via the console. Punch andreader operations are available forprogram storage, but the execution isusually via the console. Withassignable I/O, the console ouputroutine can be assigned to a lineprinter, and outputs obtained at highspeed. Alternatively, differentreaders (paper and audio) can beassigned with no change in the BASICinterpreter software.

The spare commands in AMS-80can be allocated to interface to theoperating system. For example, "Q"could be assigned to execute a jumpto the operating system. A commandcan be assigned to return to AMS-80,once in the operating system. Theseaspects of interfacing AMS-80 tooperating systems will be discussed indetail later.

Real-Time Operations

Real-time operations are requiredfor many tasks. The 8080 has thecapability of directly distinguishingbetween 8 real-time interrupts. In theAMSAT-GOLEM-80, Interrupt 0 is

194 September 1979 © BYTE Publications Inc

Circle 94 on inquiry card.

equivalent to Reset, and Interrrupt 1is reserved for the breakpoint feature.The remaining interrupts areavailable for custom software. Thetime-of-day clock is not implementedin software, but rather in hardware,using an MOS digital-clock circuit. Anumber of floppy disk interfaces,North Star in particular, do not allowfor interrupts during the disk readand write operations. Thus, a soft-ware clock would not be updatedwhen running such a disk system.This means that no real-time opera-tions could be executed withoutreinitialization of the clock each time.Using a hardware clock, the time ofday can be read at any time by usingsimple input statements from the I/Oport assigned to the clock.

Documentation

Documentation is very important.Keep all of the instructions for thevarious kits in one place. Three-ringbinders are inexpensive and can con-tain a large amount of information. Ifyou need more than 1 binder, split theinformation logically, such as hard-ware, software, peripherals, etc.When you build and test cards, noteany unusual or special things that youdid. Note any voltage or othermeasurements you made. Keep acopy of test routines you used toinitially test something. You mayneed them a few years later. The levelof documentation should be betterthan that supplied with commercialequipment. It may help you sell thesystem. It is also important to docu-ment the operational aspects of thesystem. Document how it is con-figured (an example is shown in table6), and record the operating instruc-tions so that others can operate thesystem in your absence. Note whichconnector plugs into which socket.When in doubt, document it.

Planning your Project

Your requirements are going to dif-fer from those of other people. Yourmethod of assembly can be the same,but can differ in details. There aremany manufacturers of memory andI/O cards. Some are sold fullyassembled and tested, some assem-bled, some as kits, and some as bareboards. Choosing the card that suitsyour needs at a particular time canreduce your cost. Remember that thesoftware is hardware transparent; forexample, a program designed to run

in user memory at hexadecimalmemory locations 0100 to 2000 willrun in any type of working memory,no matter who manufactured it.Therefore, it does not matter if youuse a Brand X product when the restof the club uses a Brand Y. Just ensurethat the specifications for addressingthe card are the same. (Wait states donot matter. If you need an extra waitstate, your software will take longerto execute, but you will probablynever notice the difference.)

The price of hardware is constantlyfalling. New cards are being intro-duced every month. It is possible topurchase a 32 K or 64 K-byteprogrammable-memory cardpopulated by only 8 K bytes ofmemory circuits, and add the remain-ing integrated circuits as you needthem. The price of the next 8 K byteswill probably be less than today'sprice. Purchase your hardware whenyou need it. Look around, comparethe cards made by different manufac-turers, decide how their features willfit into your system, ask for advice atyour club, and then make your pur-chase. For example, some processor

cards come with vectored interruptcapability, and some with bootstrapstart.

Summary

The details of the construction ofthe individual cards are not presentedhere because vendors supply theirown information. In the AMSAT-GOLEM-80, the hardware is inter-changeable (within limits), and theactual manufacturer of any particularcard is immaterial. The prototype hasserved to check our hardware andsoftware for members of The RadioAmateur Satellite Corporation (AM-SAT) and the Chesapeake Microcom-puter Club Inc, who have set up abulk purchase scheme for obtainingprice reductions on hardware.

This article has described anapproach to building an S-100 com-puter that is incremental and afford-able, even though it may not be thelowest cost in the long run. TheAMSAT-GOLEM-80 is an approachto a system. It may be built up as astand-alone system, or it may beoverlaid onto your existing hard-ware. ■

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i

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COMPUTER SPECIALISTS

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Circle 55 on inquiry card.

September 1979 © BYTE Publications Inc 195

Add Some Controlto Your Computer

An Output Port Tutorial

Ken Barbier

POB 1042

Socorro NM 87801

A virtually limitless number ofdevices can be controlled through asingle output port using time multi-plexing techniques. A series of 8-bitbytes is fetched from a control bufferin memory, and output through asingle port. On the receiving end, busbuffers present the data to all thedevices in parallel, but unique strobesare supplied to each device in turn, sothat it can latch its own data word.

This technique is particularlyuseful if the devices are to be locatedsome distance from the computer.

DS»0

The hardware shown in figure 1 hasbeen used to control devices over 50feet from the computer without exoticline drivers and receivers. Sinceremote addresses for each device aregenerated by the hardware, only 8data lines and 1 strobe line are re-quired. For maximum noise immu-nity, shielded twisted pair cableshould be used.

Receive Hardware

In figure 1, 16 external devicesreceive 1 8-bit byte apiece. Using the

Intel 8080, this block of data will betransmitted in about 300 „S. TheI/0(input/output) write strobeaccompanying the 1st byte triggers adelay oneshot which, after allowingmore than enough time for the blocktransmission, triggers a reset oneshotwhich clears the remote addresscounter, the 74160. This insures thatthe next block of data will be routedto the correct device in turn.

The remote address counter sup-plies a 4-bit count to the 4-line-to-16-line data selector, the 74154. As the

TYPICALOF EIGHT

»o

IOWC-ADRs| ^>

Number

Type

+ 5V Gn

IC1

7406

14 7

IC2

7404

14 7

IC3

74123

SEE FIGURE

IC4

74160

16 8

IC5

74154

24 12

Figure 1: The transmission circuitry is divided into 2 parts, the data transmission (DO through D7) and the address. The address isdecoded by a counter which determines which 1 of 16 devices is being used. The write strobe accompanying the data triggers a delayoneshot (IC3a) which triggers a reset oneshot (IC3b) which clears IC5, the remote address counter.

196 September 1979 © BYTE Publications Inc

RADIO SHACK COMPUTER OWNERSTRS-80 MODEL I AND MODEL II

TRS80

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BYTE September 1979 197

74160 advances its count on the risingedge of its clock, it will initiallysupply address 0 to the 74154 untilthe trailing edge of the negative goingI/O write strobe. This same strobe isthe "data" supplied to the 74154, andso will appear on each of the outputsof the 74154 in turn. This constitutesthe 16 remote addresses.

For expansion, 1 additional counterstage could be used to generate "first16" and "second 16" control signals todouble the number of devices.

Driver Programs

The example shown in figure 1 isfor 16 devices. Every time we want tooutput a control to any one device,we must output all the control words.OUCNT is an 8080 routine designedto accomplish this (see listing 1). Thecalling program first loads the correctbit patterns into the correct bufferwords, then sets the flag at memorylocation FLAG. This flag is used toprevent needless outputting of thecontrols. In a complex control pro-gram, many segments of the oper-ating system may need to change thestate of the devices at irregular inter-vals. In such an implementation therewill be a fixed program cycle, withmany tasks called in turn to performtheir functions. At some point in thecycle, time will be allotted to outputour controls. If no program segmentsor tasks have called for any change inthe controls, it is not necessary totransmit them, and the flag will notbe set. But when it is set, we willtransmit all the controls, after clear-ing the flag.

Controlling Relays

Typical applications for this tech-nique might include driving remotedisplays, with 32-decimal digits beingtransmitted, 2 per 8-bit byte. Or, as isshown in figure 2, 8 relays can becontrolled by each 8-bit byte.

The simplified schematic of figure 2shows a relay driver circuit capable ofcontrolling 8 relays. The 8 bits of dataare latched into the 74175s on the ris-ing edge of the clock, so our negativegoing strobe can be used as is. If lat-ches such as the earlier 7475 are used,the strobe would have to be inverted,since the output of a 7475 follows theinput whenever the clock is high. Ineither case, any relay whose corres-ponding bit is not changed will re-main in the previous state, as its cor-

;OUTPUT CONTROLS

CONTR

EQU

OUCNT:

LDA

AN I

RZ

MVI

STA

LXI

MVI

OUCN1:

MOV

OUT

INX

DCR

JNZ

RET

FLAG:

DB

BUFFER:

DS

OUTPUT PORT ADDRESS

FLAG

;NEED ACTION?

OFFH

;NO, RETURN

A,00

;YES, CLEAR FLAG

FLAG

H.BUFFR

;GET CONTROL BUFFER ADDRESS

O0FH

;SET COUNTER

A,M

;GET CONTROL DATA BYTE

CONTR

H

INCREMENT ADDRESS

C

;DECREMENT COUNTER

OUCN1

;CONTINUE IF NOT DONE

;ELSE, RETURN

0

;ACTION FLAG

OFH

;CONTROL BUFFER

Listing 1: 8080 assembler routine to output control signals to 1 of 16 devices. CONTR isequated with the desired output port address.

responding latch is reloaded with thesame data as before. (The type ofNPN driver transistor will have to beselected to match the current andvoltage requirements of the particularrelay used.)

Relay Control Program

Obviously, if we need to control 8relays with 1 byte, we do not want tochange the state of all of the relays atthe same time. This complicates thesoftware required slightly. In the 8080program shown in listing 2, a changerelay subroutine allows us to changethe state of 1 relay at a time. We must

supply the subroutine with thenumber (hexadecimal 0 thru F) of theword in the buffer corresponding tothe relay driver board, and a relaynumber (1 thru 8). We must alsospecify whether we want to turn it onor off. At the correct time, we put theword number in register C, the relaynumber in register E, and set registerA to 1 for on, or 0 for off, and callCHGRY. The next time the operatingsystem calls OUCNT, only our

+ 5V

D0 Q>

74175

CLOCK

2Q3Q4Q

D6 O-

13

■o

10

•o

m

ID2D3D4D

CLOCK

74175

IQ2Q3Q4Q

■o

■o

■o

15

■o

Figure 2: A relay driver board capable of controlling 8 relays. The state of the relay, onor off, is latched into the 74175 until a following strobe is received directing a change instate.

198 September 1979 © BYTE Publications Inc

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BYTE September 1979 199

"^exclusively from BITS inc.

TRS-80* Software FREEwith this Definitive Text!

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18 chapters of solid,accurate programminginformation:

• Debugging techniques

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• Array and table handling

• Number base conversion

• Floating point arithmetic

• Programmed input/output

• Stack pointer usage

The last part of the book is soft-ware, an editor/assembler whichwill run on any 8080 or Z80 ma-chine and a debugging monitor.

Send in the coupon suppliedwith the book and receive FREEthe object programs of the editor/assembler and debug on eitherpaper tape or on cassette tape forthe TRS-80 microcomputer.(Loads in Level I with 16KRAMor Level II.)

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G Practical Microcomputer Pro-gramming: The Z80 by W J Weller

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CHANGE RELAYENTER WITH:

CONTROL WORD NUMBER IN (C)RELAY NUMBER IN (E)(A) = 1 TO TURN RELAY ON(A) = 0 TO TURN RELAY OFF

CHGRY:

LXI

H.BUFFR

;GET BUFFER START ADDRESS

MVI

B,0

;ADD WORD NUMBER

DAD

B

ANI

0FFH

;TURN ON OR OFF?

JZ

OFF

CHGR1:

DCR

E

TURN IT ON

JZ

CHGR2

;SHIFTBITTO RELAY

RLC

; POSITION

JMP

CHGR1

CHGR2:

ORA

M

TURN THIS ONE ON

MOV

M,A

CHGR3:

MVI

A.0FFH

;SET CONTROL FLAG

STA

FLAG

RET

;AND RETURN

OFF:

MVI

A.0FEH

TURN RELAY OFF!

OFF1:

DCR

E

;FORM MASK WORD

JZ

OFF2

;SHIFT "HOLE" TO

RLC

; RELAY POSITION

JMP

OFF1

OFF2:

ANA

M

TURN THIS ONE OFF

MOV

M,A

JMP

CHGR3

;AND RETURN

Listing 2: This 8080 routine allows a state change for only 1 relay in a set of 8 instead ofchanging all relays at once.

INITIALIZATION SUBROUTINE

IN IT;

MVI

A,00

OUT

CONTR

MVI

A.14H

INIT1:

LXI

H.BUFFR

MVI

C0FH

INIT2:

MVI

M,00

INX

H

DCR

C

JNZ

INIT2

DCR

A

JNZ

INIT1

CALL

OUCNT

RET

;CLEAR REMOTE ADDRESS; COUNTER;CLEAR BUFFER AND; DELAY ROUTINE;LOOPTIME IS 250 USEC; SO DO IT 20 TIMES

TO ALLOW RESET

; OF REMOTE ADDRESS,

THEN OUTPUT ALL ZEROS;AND RETURN

Listing 3: Initialization routine to clear the address counter, buffer, and outputs all 0s todevices connected to system.

selected relay will change state, eventhough all the controls are output.

Error Free Operation

To insure that all controls havebeen received correctly, some sort offeedback to the computer can be pro-vided. In actual practice this is usual-ly unnecessary, but if it must beimplemented, there are several pos-sible techniques.

First, 74180 parity generator andcheckers could be used to generate aparity bit on the transmit end, andcheck it on the receive end, sendingback an interrupt if any word re-ceived is in error. This would addonly 2 more signal conductors to the9 already in the cable. Additionally,at the end of the delay oneshot time(and before the reset occurs), theremote address counter can be tested

to insure that it has reached the all Isstate. A count error signal can beORed with the parity error signal toproduce a single interrupt in caseeither error should occur. The oper-ating system can then try thetransmission again, or at least indi-cate its existence.

System Initialization

Since, upon initial application ofpower, the states of the latches andthe 74160 counter will be indeter-minate, the initializing subroutine oflisting 3 should be called at power onand reset times. This will clear theaddress counter, the buffer, and out-put all 0s to all devices.

I hope this short discussion of out-put port techniques will help readersto understand how the computer canbe interfaced to the real world. ■

200 September 1979 © BYTE Publications Inc

Expansivebut not expensive

MicroAge introduces for Horizonand Alpha Micro Systems, the mostpowerful Hard Disk Units You'veEver Seen.

Welcome to "Hard" Times: a newage of hard disk cartridge drivesfor Horizon and Alpha Micro ...so powerful, so reliable, soeconomical, you've never seenanything like it. Fast, easy andversatile: the revolutionary newFujitsu M2201 with 40(formatted) megabytes ofstorage ... and the dynamic CDCPhoenix with 27 (formatted)megabytes. Both are operatedwith North Star and Alpha Microcommands. Added capacitymeans the ability to fully utilizethe complete range of softwareand capabilities of North StarHorizon and Alpha Micromainframes.

But their family interfacecompatibility is not all that'sexpansive. Speed and economyare impressive, too. Super-fastaccess time means no waiting forcommand execution ... easyhandling of large files. And theprice? Unbelievably low for thismuch flexibility, power, speedand capacity. And the low priceincludes the hard disk drive,S-100 controller, softwareinterface, cords and disk pack.

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Ask your dealer about Hard Times — the Fujitsu M2201 and CDC Phoenix drives from MicroAge. Available toqualified dealers and OEM's. If a dealer is not available in your area, call 800-528-1415.

Circle 212 on inquiry card.

BYTE September 1979

201

Text continued from page 6:

The scope of the new homebrew design has nowexpanded to include relatively high-speed serial RS-232Ccommunications among the homebrew node, theWestern Digital P-engine, the Able/60-Synclavier, andother computers from time to time. I intend to use RS-232C at 19.2 K bps as the communications discipline,primarily for its universality. Today one can get almostany computer with a standard 25-pin D connector set upfor the RS-232C discipline, at speeds ranging from alethargic 110 bps to a maximum of 19.2 K bps. Thisupper-limit of speed is not exceptionally fast (about1800 bytes per second is the equivalent in a useful mea-sure), but the existence of these standard signal levels andstandard connectors argues for this kind of approach.

The diagram of figure 1 shows how the overall concep-tion of the system stands at present. The homebrew 6809simultaneously provides a facility to directly execute

Figure 1: How the 6809 homebrew computer fits into a biggersystem. The new 6809 computer will serve as a central com-munications node for multiple computers involved in this per-sonal system. At present 2 complete computer systems areinvolved, with serial communications via the 6809 node, whichis the subject of this homebrewing series. The Able/60 hasseveral specialized peripherals which will be used for personalresearch purposes, such as, high-speed 16 channel analog-to-digital input conversion and a real-time clock with 1 fis reso-lution. In this diagram, mass storage equipment is not shown,but it is a part of each computer: the Able/60 computer includes2 5-inch floppy drives, and 2 full-size floppy drives as its massstorage complement. The P-Engine machine includes 2 doubledensity, standard-size floppy disk drives.

6809 code for experimental purposes, and a more per-manently useful function of a common communicationsnode which can be the subject of various serial com-munications strategies relative to the other processors.

Lest readers wonder, this is and remains a personalcomputer. It is true that the system is getting a bit largefor one person to operate all of the terminal and musickeyboards simultaneously, yet it resides in my homealong with various other facilities of the complete com-puter experimenter: electronics shop, woodworkingshop, and the beginnings of a machine shop.

This expanded conception of function for the home-brew 6809 barely changes the hardware design detailsoriginally conceived. The computer will have 16 K bytesof memory to start, several terminal ports, severalparallel ports, and space for 4 K bytes of ultraviolet,erasable read-only memory. The read-only memory willcontain the implementation of low-level, communi-cations-monitor software and key parts of a reverse-polish notation, stack-oriented, threaded interpretivelanguage. Remember that the conception of a homebrewor commercial system made of modular components canchange considerably in detail as a result of time andresources available.

As the system design develops from this initial inten-tion, its actual detail may prove inconsistent with what Ihave conjectured thus far. Recognizing this startingpoint, I invite readers to follow in on a guided tour of thecurrent state of my thinking about this new, homebrew,microprocessor system project. Let's see how the centralprocessor bus design comes out, what logic blocks will berequired, and let's have some preliminary thoughts on the

ORGAN MANUALS

TO STEREO

MANUALAU0IOMIXINGSYSTEM

0 TO 16 MUSIC

CHANNELS(PREMIXED TOSTEREO)

REAL TIME CLOCKADC'S ■ 16 CHANNELS

PARALLEL I/O SERIAL I/O

SYNCLAVIER

NEW ENGLANDDIGITAL

WESTER DIGITAL

•ENGINEMACHINE

0-8MUSIC

CHANNELS(PREMIXEDTO STEREO)

SPARE SERIAL CHANNELS

RS-232C

HOMEBREW 6B09 - COMMUNICATIONS NODE

ALF PRODUCTS

FUTURE

COLOR GRAPHICS

DISPLAY

PROCESSOR

MARANTZ-SUPERSCOPE"VORSETZER"

STEINWAY PIANO OUTPUT

202 September 1979 © BYTE Publications lnc

COME TO

AST

INESS

HYNES AUDITORIUM, PRUDENTIAL CENTER, BOSTON

Interested In Personal Computers?

This is the place for you! You'll meet and talk withhundreds of manufacturers, distributors and retailers...all showcasing their new 1980 Micro, Mini and SmallComputer Systems.

You'll see them all...Radio Shack, Pet, RCA,Compucolor, Heathkit...you name it! All the majorterminal and peripheral companies too, plus softwaredevelopers magazine editors and book publishers. Yes,it'll be the largest showing of personal computerhardware, software and services ever assembled inthe Northeast!

You'll be enthralled, entertained and educated. You'llsee computer art, graphics and animation. You'll hearcomputer synthesized music, watch computerizedamusements, play electronic and video games wl

and attend scores of free tech talks andbriefings given by internationallyrecognized speakers. And you maywin a free computer given awayas a door prize! Don't miss thelargest gathering of computersand computerists! Nopre-registration necessary.Tickets available at the door.Adult admission $5.00.

Produced by Northeast Expositions, P.O. Box

Interested In Business Systems?

Interested in Business Systems? This will be your oneopportunity to see all of the Mini, Micro and ModerateSized Computer Systems under one roof. Yourattendance at this show is a must if you, or yourcompany, are contemplating the purchase of any typeof computer or office equipment.

You'll see them all...the big ( and small) names incomputers, data and word processing eqiupment,peripherals and software. You'll attend dozens of free,easily-understood briefings on how computers canhelp you in your business or profession.'*So if you're considering a computer or computer-related service...starting yourown computerbusiness or changing your job within themputer industry...or if you'd just like to learnmore about computers as they relate toyour personal life and to yourbusiness or profession, come tothe show to see theComputerized World ofTomorrow...Today. And bringthe entire family, It's a fun-filled educational experience.No pre-registration necessary.Tickets available at the door.Adult admission five dollars.

lage, MA 02147 (617) 522-4467

Circle 284 on inquiry card.

BYTE September 1979 203

Circle 401 on inquiry card.

ZS - SYSTEMS

64K RAM BOARD

The ZS-SYSTEMS 64K RAMboard is designed to operatein any Z80 based microcom-puter having S-100 bus. Ituses 16K dynamic RAM chips,& features:

—Board select

—Bank select

—Transparent on-boardrefresh

—2 or 4MHz operation(w/ no wait state)

—Memory disable

FLOPPY DISKCONTROLLER

Handles with no modificationup to:

* 4 standard 8" drives(Shugart or compatible) or

* 3 minidrives 5"

Run with 2 or 4 MHz CPU

Compatible with Cromemco

system, Fully assembled,

burned in, & tested

Available from stock

to 60 days

As low as $500.00 in

quantities of 100

Price of one $649.00

PC board only $59.00

With 16K RAM $359.00

Plus shipping charges

Use CP/M Disk Operating System

Using the 1771 LSI controller

Price oi one $245.00

SEND FOR FREE INFORMATION

6 months warranty on our boards with norma/ use

Zs SYSTEMS

PO Box 1847, San Diego, CA 92112(714) 447-3997

16K STATIC RAM

with$275 450 ns$300 250 ns

memory chips

Assembled, Tested and Guaranteed

Static TMS 4044 or equivalent - Fully Static 4Kx1 Memory Chipsfor full DMA capability, no tricky timing problems.

Fully S-100 Bus Compatible - All lines fully buffered. Dip SwitchAddressable in two8K block, 4K increments. Write Protectablein 2 blocks, Memory Disable using Phantom, Battery back upcapability.

Bank Select - Using output port 40H (Cromemco softwarecompatible)-addressable to 512KB of Ram for time share orMemory Overlap, also has alternate ports 80 H, COH.

Guaranteed - Parts and labor for one year. You may return theundamaged board within 10 days for a full refund.

Orders - You may phone for Visa, MC, COD ($4 handling chargesfor COD) orders. Personal checks must clear prior to shipping.Shipping-Stock to 72 hours normally. Will notify expectedshipping date for delay beyond this. Illinois residents add 5%tax. Please include phone number with order.

S.C. digital

P.O. Box 906 Phone:

Aurora, IL 60507 (312)897-7749

partitioning of the system into cards within the 6-slotbackplane previously described.

Designing The Logic Of The System

The task at hand is to design the central processor cardfor this homebrew computer. This is the starting point forthe design of the whole system. Detail choices made inthe processor card's arrangement impact every other carddesigned for the system.

We know, that the system must have 16 address linesand 8 data lines because it uses a 6809 processor architec-ture, and simplicity dictates avoidance of extra logic formemory paging schemes. But which 24 lines of the 40 re-maining in the backplane bus should be committed towhich particular uses? Every board in the system must beconsistent with this detail choice. The choice is madetrival by the fact that, except for aesthetic and symmetryreasons explained below, one backplane line is as good asthe next.

If we were building a computer consistent with plugcompatible backplane bus designs such as the SS-50 ofSouthwest Technical Products Corporation, or the In-stitute of Electronic and Electrical Engineers (IEEE) S-100standard bus, these choices would be crucial to that goalof plug compatibility. However, a homebrew system is ahomebrew system, so our plug compatibility will be atthe level of integrated circuits, not at the level ofbackplane buses.

Designing The Logic Of The System—Backplane Setup

As noted in the July BYTE page 194, the power supplywiring of the backplane has been committed to the outer-most pins of the sockets. The assignment of power supplypins used 32 of the 72 pins available, in order to takeadvantage of the heavy copper wires of the buses. Thepower supply wiring commitments were made consistentwith a symmetry principle: if a board should beinadvertently rotated 180 degrees and plugged in, allpower buses will map into identical power buses. Theoutermost power bus is the —12 V analog power bus.Proceeding inward, the next symmetric pair will be usedfor the +12 V analog power; the next pair of buses is forthe +5 V main logic power supply. The innermost powerbuses are the central system ground buses. In table 1, alisting of backplane bus connections, these initialassignments of power pins are shown in shade (a).

The power supplies used in building this system areprovided by relatively inexpensive modular buildingblocks from James Electronics. The +5 V logic power isprovided by a single regulated supply rated at 6 A. The 2analog supply voltages are provided by separate modulesrated at 1 A. In the photographs of the physical hard-ware, these modules are shown as mounted, prior towiring.

In the design of the backplane bus once the power sup-ply committments have been made, the next items to con-sider are the data and address lines. Continuing the pro-cess of symmetrical allocation, the 16 address lines and 8data lines should be assigned to bus pins in such a mannerthat if a card is rotated, data lines will map into datalines, and address lines will map into address lines. Theaddress lines are split into 2 groups of 8 connections oneither side of the symmetry axis. The data lines are

204 September 1979 © BYTE Publications Inc Circle 331 on inquiry card.

ONE PACKAGE DOES IT ALL

Includes these Application Programs . . .

Sales Activity, Inventory, Payables, Receivables, Check/Expense Register,Library Functions, Mailing Labels, Appointments, Client/Patient Records

'MICRO-AP MICRO-AP MICRO-AP MICRO-AP MICRO-AP MICRO-AP MICRO-AP MICRP MICRO-AP MICRO-AP MICRO-AP MICRO-RO-AP MICRO-AP MICRO-AP MICRO-AP MICRO-AP MICRO-AP MICRO-AP MICRO-AP MICRO-ICRO-AP MICRO-AP MICRO-AP MICRO-AP MICRXRO-AP MICRO-AP MICRO-AP MICRO-AP MICRO-iP MICRO-AP MICRO-AP MICRO-AP MICRO-AP MICRMICRO-AP MICRO-AP MICRO-AP MICRO-AP MICRO-i-AP MICRO-AP MICRO-AP MICRO-AP MICRO-AP MICR~|MICRO-AP MICRO-AP MICRO-AP MICRO-mp MICRO-AP MICRO-AP MICRO-AP MICR■MICRO-AP MICRO-AP MICRO-AP MICRO-|\P MICRO-AP MICRO-AP MICRO-AP MICRIMICRO-AP MICRO-AP MICRO-AP MICRO-IvP MICRO-AP MICRO-AP MICRO-AP MICR

AP MICRO-AP "BB^^m ^— ^"""Bi BOAP MICRO-AP Ml

RO-AP MICRO-ARM B KRO-AP MICRO-AP t

AP MICRO-AP mB ■ Bj^KffwjH Bo-AP MICRO-AP Ml

RO-AP MICRO-ARM BcRO-AP MICRO-AP >

AP MICRO-AP mB H___^^^B|a Bo-AP MICRO-AP Ml

RO-AP MICRO-ARM BdRO-AP MICRO-AP H

AP MICRO-AP mB Bo-AP MICRO-AP Ml

RO-AP MICRO-ARM BpRO-AP MICRO-AP t

AP MICRO-AP MICRO-AP MICRO-AP MICRO-AP MICRO-AP MICRO-AP MlRO-AP MICRO-AP MICRO-AP MICRO-AP MICRO-AP MICRO-AP MICRO-AP KAP MICRO-AP MICRO-AP MICRO-AP MICRO-AP MICRO-AP MICRO-AP MlRO-AP MICRO-AP MICRO-AP MICRO-AP MICRO-AP MICRO-AP MICRO-AP *

RANDOM, MULTI-KEY RECORD RETRIEVAL under CP/M, CDOS, IMDOS, ADOS

SELECTOR Ml ALLOWSINSTANT RECALL OF ANYRECORD USING ANY IN-FORMATION ITEM IN THERECORD. That statementdeserves re-reading, be-cause that ability makesSELECTOR III the mostpowerful Date Base Man-agement System in micro-computers today!

With SELECTOR III

you can...

• define a record format,assign retrieval keys, andbegin entering data in min-utes.

• create sorted pointers torecords matching your spe-cif or range of requirements.

Circle 213 on inquiry card.

• automatically generatereports with control-breaksummaries and unlimitedvariety.

an application on-hours instead of

• bringline inmonths

SELECTOR III comes com-plete with eight applicationprograms that perform thetasks listed at top of page.And, since it's distributed insource code form, you caneasily add subroutines to dospecific computations orfile updates.

SELECTOR III runs underCBASIC Vers. 1 or 2, and ispriced at $295. SELECTOR

III-C2 is dedicated to Vers. 2only, runs about twice asfast, and costs $345.

Both systems are available ina variety of CP/M, diskettesize and density formatsincluding IBM 8"; North Star;Micropolis; TRS-80; Pro-cessor Tech Helios II; Altair;iCOM; Dynabyte; Imsai;and others.

| Available from computer stores nationwide: I

LIFEBOAT Associates

2248 Broadway, Suite 34,New York, N.Y. 10024 • (212) 580-0082

Or order direct from ■

MICRO-AP

■ 9807 Davona Drive, San Ramon, CA 94583 I(415) 828-6697 |

I

BYTE September 1979 205

allocated into 2 groups of 4 connections. Continuing thelisting of the backplane connections in table 1, theseassignments of 24 address and data pins are shown inshade (b). At this stage in the allocation of logical signalsto the bus, 24 of 40 available pins have been used, leaving16 pins still to be determined.

The next item to consider is the set of lines which con-

(-12V)--

-- (-12 V)--

= = = = =(+12 V) == = = = =( + 12 V) =

13 ::;: = A4 X:X:::x:x:::::::::x:x:x:x::

14 •:•;' = A5'+:;:;:;:+:;:+:;:;x;:;:;:;:;:;:;:;:;

16 :•:• =.A7 ;x+:::;:;x::::::::::::::::;::::::x;

17 = RESET

18 = NMI

19 = unassigned

20 = ENABLE

21 = 14 •:

22 d 15 j;

23 = 16 |:

24 = 17 ::

25 ::X=.D4'.

26 :•:>= D5:

(a)

(b) =

72717069

+ + + + + + + MAIN PWR ( + 5 V)+ + + + + + + 68

+ + + + + + + MAIN PWR ( + 5 V)+ + + + + + + 67

GROUND (0 V) 66

GROUND (0 V) 65

9 :x = ao y^v'xjxoxlx^xjxjxlxlxjxjxjxjx '■:'■: 64

10 8'= Ai'Sx'xxS^ di ='•:•: 63

11 :•:■ =.A2 i&SS&S:^^ R? f.x: 62

12 x:'= A3"^S^:^SS^SS^S:§SSSSS:^ D3 =':::: 61

10 = 60

11 = 59

12 = 58

13 = 57QENABLE = 56

unassigned = 55

IRQ = 54

RW = 53

^i^x+x "as '= *: 52

x+x'+x'l "A9^=:x 51

;:-:-:jSjij:-:Aio =;:•: 50

:•*:*:** Ali'=:::: 49

:A12 =:x 48: A13 = :>: 47

27 :x:=.P6;xjxj:v:x:;:j:vx;:j:v:x:v:;:v:v:x:x:xXv:x:;:;x;AH = ::j: 46

28 :*:= .^J:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-S^ .=.:•:: 45

29 GROUND (O V) 44

30 GROUND (0 V) 43

31 + + + + + + + MAIN PWR ( + 5 V)+++ + + + + 42

32 + + + + + ++MAIN PWR ( + 5 V)++ + + + ++ 41

33 = = = = = = = = =(+12 v)= = = = = = = = = 40

34 = = = = = = = = =(+12 V)= = = = = = = = = 39

35 - ( - 12 V) 38

36 ( - 12 V) 37

(c) =

nect the central processor to the external world. Theselines are the essential timing and control signals whichdefine the discipline of the bidirectional 8-bit bus used bythe microprocessor. In the specifications of the 6809, thefollowing signals are defined which have relevance to theoutside world:

• RW = Read versus Write bus direction relative tothe processor.

• ENABLE = Clock ouput ("Phi 2") of processor.

• QENABLE = Quadrature clock of processor.

• RESET = system reset line to processor and allperipherals.

• MRDY = memory-ready line, for use with slowmemory devices.

• BREQ = bus request for direct memory access(DMA).

• BA = bus available.

• BS = bus status.

• FIRQ = fast interrupt request.

• IRQ = interrupt request.

• NMI = nonmaskable interrupt request.

The simplest and most direct way to deal with these 11signal lines would be to bring them out to the backplane.But do we really need all these signal lines in this pro-cessor? Might it be more useful to commit a majority ofthe remaining 16 lines to interrupt activities, rather thanhaving nonessential copies of the lines coming from theprocessor circuit? For example, we may prefer to incor-porate 8 separate interrupt lines in order that each of apossible 8 peripheral devices could have a dedicated line.If this is to be accomplished, then the total commitmentof noninterrupt lines to the backplane must be 8 linesinstead of the mixed selection of 3 interrupt lines and 8signal lines shown above. How can we modify this set ofbackplane signals given the limitations and purposes ofthis particular design?

First, remember that this application is a simple andlimited one in which no direct-memory access is beingimplemented, and that all memory will be fast enough todrive the processor at full speed. Given this requirement,the 2 signals memory ready (MRDY) and bus request(BREQ) can be removed from the set seen by the externalworld beyond the processor card. We have thus reducedthe backplane line count to 9 lines, nearly enough toallow 8 distinct interrupt lines.

The next items to question are the bus available (BA)and bus status (BS) signals. These are used to decode 1 of4 possible states: normal operation, interrupt acknow-ledge, synchronization acknowledge, and bus grant (haltacknowledge). Of these, the limited goals of the present

Table 1: An allocation of backplane signals. As described in thetext, this backplane signal set provides for 8 bidirectional datalines, 16 address lines, 8 individual fast interrupt lines used witha (slow) software polled strategy, 2 direct interrupt lines, and 4essential timing signals for the 6809 and its relationship with theexternal world. The assignment of these lines is kept sym-metrical, so that while the processor may not work if any boardin the system is inadvertantly plugged in the wrong way, nomajor conflicts will occur that could damage a gate or buffer.The shades indicate stages in the backplane allocation processdescribed in the text: (a) pins are the power connections; (b) pinsare the address and data connections; (c) pins are the 16 linesallocated to processor control signals and interrupts.

206 September 1979 © BYTE Publications Inc

FALL 1979

0001010111110100010101110101000000010000101111101000101010111110100010101110

JAM€S MARTIN

S€MINAR

0001010111110100010101110101000000010000101011111010001010111010100000001000

Future Strategy,Management,

& Design for:

■ Distributed Processing

■ Data Base

■ Networks

■ Corporate Strategy

Washington, D.C. October 15

Los Angeles October 22-26

Boston November 5-9

Chicago November 26-30

Seminar Fee: $1150.00

■•- • .. _ __. : .

0001010111110100010101110101000000010000101011111010001010111010100000001000

CALL OR WRITE:

(213)476-9747

Circle 364 on inquiry card.

P.O. BOX 49765, LOS ANGELES, CA.90049 (213)476-9747

BYTE September 1979 207

WANTED:

ASSISTANTEDITOR

?n

Job Opportunity

onComputing, BYTE's companionmagazine, is growing rapidly. We have animmediate opening for the job of assistanteditor of onComputing, a McGraw-Hill dpublication. This creative opportunityoffers the potential for growth in the,,exciting world of publishing.

Candidates for this positionshould have a firm grounding inpersonal computer hardware andsoftware, and should have theability to write and edit clearly andaccurately. A technical degree andsome journalism experience aredesirable but not mandatory. «C;._onComputing covers the world of personal computing, but iswritten in a less technical style than BYTE. It is aimed at thebeginner, professional person, student, and anyone interested inlearning more about personal computers.

onComputing is located in Peterborough NH, the heart of thesouthern New Hampshire vacation region. Conveniently located90 minutes from Boston, Peterborough offers the benefits of awide variety of cultural activities, plus the peaceful seclusion ofthe country.

If this position sounds interesting, we'd lixe to hear from you.Send your resume in confidence to Chris Morgan, Editor-in-Chief,onComputing, 70 Main St, Peterborough NH 03458, or call (603)924-7217.

Time is of the essencel

system make the only externally relevant state "normaloperation" if we can confine interrupt handling logic tothe processor card. Can this be done? The answer is"yes", if we define fixed read-only memory vectors for allinterrupts, and eliminate the need to decode interruptacknowledge externally for purposes of altering the inter-rupt vector locations. Thus the backplane signal require-ments have been further reduced to 7 lines, still allowingthe 3 originial interrupt lines to come out to the externalworld off the central processor card.

Now let's examine the interrupt handling capabilities ofthe processor. Of the 3 available interrupts, the fast inter-rupt is the most general. The reason for this is that it onlystacks away the essentials of the processor state whenacknowledging the interruption with a branch throughthe FIRQ vector location, hexadecimal address FFF6.These essentials are the condition code, and the returnaddress. In contrast, the NMI and IRQ interrupts alwaysstack away the entire current contents of the central pro-cessor's set of registers. If we use the FIRQ signal for mostinterrupt activity, then, when speed is needed, only thoseregisters which are used by the interrupt routine can bestacked away using the multiple register push and pullinstructions. If the operation of the NMI or IRQ (ie: com-plete protection) is required, the multiple register opera-tion of push and pull can be extended to cover all the pro-cessor registers using the proper "post-byte" which selectsregisters.

What about devoting the FIRQ interrupt input to 8 dif-ferent possible sources, using a concept of a software-polled flag register and a parallel input port to prioritize"who called"? This elminates 1 more line from theoriginal backplane signal requirements, while adding 8interrupt lines labeled 10 through 17. We keep the NMIand IRQ lines available for truely high-priority interruptsignals which must go in directly without much softwaredecoding. Our result then is the final backplane signal setlisted in table 1, with this last set of additions shown inshade (c). Two lines are left uncommitted at this stage, incase an essential signal concept is omitted. One or moreinterrupt lines (10 through 17) can be sacrificed, if morethan 2 lines must be added due to some shortcomings.

With this general discussion of the system's backplanecomplete, I will continue these notes next month with amore detailed sketch of the system's most important card:the central processor module. Following this designdiscussion, the final installment on the processor modulewill be a short description of the detailed schematic as Iwire it.■

Articles Policy

BYTE is continually seeking quality manuscripts written by indi-viduals who are applying personal computer systems, designingsuch systems, or who have knowledge which will prove useful toour readers. For a more formal description of procedures andrequirements, potential authors should send a large (9 by 12 inch,30.5 by 22.8 cm), self-addressed envelope, with 28 cents US postageaffixed, to BYTE Author's Guide, 70 Main St, Peterborough NH03458.

Articles which are accepted are purchased with a rate of up to $50per magazine page, based on technical quality and suitability forBYTE's readership. Each month, the authors of the two leadingarticles in the reader poll (BYTE's Ongoing Monitor Box or"BOMB") are presented with bonus checks of $100 and $50. Unso-licited materials should be accompanied by full name and address,as well as return postage.

208 September 1979 © BYTE Publications In

Model DMB-6400 Series dynamic 64k byte RAMS incorporate thefeatures which are standard in the DM-6400 Series and adds thefollowing capabilities:

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MEASUREMENT

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incorporated

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Circle 215 on inquiry card.

BYTE September 1979 209

Circle 133 on inquiry card.

Circle 198 on inquiry card.

Belais' Master Index to Computer Programs

in BASIC Gives You Access to $14,836.14Worth of Computer Programs for Just $7.95!

Now Available Off-The-Shelf

You paid hundreds or even Ihousands of dollarslor your new microcomputer. By now it may bedawning on you that a $1,000 computer with nosoftware is just $1,000 worth of scrap metal!

But computer programs cost money. In a recentsurvey of 1,984 computer programs offered forsale in the top three home computer magazines,Ihe average price was found to be $27.94. What arip-off!

You don't need to spend hundreds of dollars toget a complete library of programs for your com-puter. Thai is, you don't if you have Belais' MasterIndex to Computer Programs in BASIC.

Belais' Master Index gives reviews of 531 pro-grams that have appeared in 10 major homecomputer magazines—programs (hat you cantype into your computer for free!

This large 81/; x 11, 192-page directory ispacked with information. This is not just a simplelisting of article titles, but a complete referencework!

Each BMI review is complete—it has everythingyou need to know about a program. A brief indexline capsulites Ihe review for quick referenceSource information shows you where the programcan be found. Any updates or corrections areshown so you know the program is accurate andcomplete. The lext of the review gives you a fulldescription of what the program does. In addition,Ihe review gives detailed technical informationabout what hardware and software the programneeds. Everything you need to know is right atyour fingertips!

We don't provide the program listings them-selves, of course. But we do tell you where youcan pick them up—even ones that appeared inprint years ago.

You don't have to be a programming wizard touse Belais' Master Index. That's because BMI listsonly finished, ready-to-mn programs in BASIC,the easy-to-use language enjoyed by millions.

Even if you're a master programmer, you'llappreciate Belais' Master Index. Why slave awayhours, days, or even weeks writing a program

when someone else has probabfy already donethe work for you? These programs are working,documented, and ready-togo.

Programs like: Circuit Design, Psychoanalysis,PASCAL Compiler, Forrester's World Simulation,and Color T.V. Tester. Never again will you havetrouble answering that question. "But what arehome computers good for?"

Then again, there's always MONEY. Maybe youhaven't (hough of all the ways your "fun" com-puter could turn out a little of the green stuff foryou. Maybe you haven't—but a bt of other peoplehave, and they've written up their ideas for youto use. Belais' Master Index lists dozens of programs that you can use to set up your own business

If you already have a business. Betas' MasterIndex has the programs to turn your home com-puter into a full-fledged business system. Generalledger, billing, payroll, mailing lists, word proces-sing^—no matter what type of business you have,Belais' Master Index has the programs you need,

All this and save $2.00, too! The cover price ofBelais' Master Index to Computer Programs inBASIC is $9.95. But because you're buying by mail,we don't have to pay a commission to a bookstore.So we're going to pass (he savings along to you.Order now and you can get your copy of Belais'Master Index for just $7.95!

To order, write you name, address, and thewords "Beiais' Master Index" on a piece of paper.Make out your check for $7.95 plus $1 shipping(Calif, residents add 54$ sales tax).

If you want to use your VISA or Master Chargecard, give the total for your order, your accountnumber, the expiration date of your card, and yoursignature.

Send your order to Falcon Publishing.Dept. T. 140. Riverside Ave. P.O. Box 688. BenLomond, CA 95005.

We absolutely guarantee you'll find Belais'Master Index one of the most useful books on yourshelf. If you're not completely satisfied, return itto us within 30 days and we'll refund every centyou paid. You can't lose, so order NOW?

TRS-80 SOFTWARE32K with 2 DISK DRIVES

PAYROLL SYSTEM $235

Includes: a) File Maintenance

b) Payday Entries

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Handles up to 300 employees per diskette.Automatically calculates FICA, FED. TAX,UNEMPLOYMENT and much more.

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Enjoy the challenge andexcitement of learning aboutmicroprocessing hardware - howit functions and how to repair it -by actually building your ownequipment as you learn.

National Technical School's Microcomputer Division offers three suchlearn-by-doing courses that you can enjoy at home, in your spare hours. Eachcombines clear, concise lessons with Heath and NTS-designed digitalequipment-a combination our students tell us makes for "lively" home study.

Find out more about these valuable NTS Microcomputer Courses, Send todayfor our colorful 65-page catalog-it's FREE!No obligation. No salesman will call. Approved for veteran training.

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TRS-80 FUN GAMESat NEW LOW COST

CRAPS - all types play - no player limit $6.95

BIG SIX ■ 40 different number combo $5.95

BIORYTHM - different from any others $5.95

PERPETUAL CALENDAR from Christ to infinity $4.95

SAVE $4.80 -

Order all 4 Programs for only $19.00

BLANK C ID CASSETTES - Highest Quality 1-5

$1.30 ea; 6 10 $1.15 ea; 11-20 $1.05 ea;

over 20 $.95 ea. Any quanity only $.85 ea.

with order of $19.00 for 4 games.

Dontho ScientificP.O. Box 864, Mich. City, Ind. 463BO

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Please ship the following:

NATIONAL TECHNICAL SCHOOLS

4000 South Figueroa Street • Los Angeles, California 90037Please rush your FREE 65-page color catalog

Name

Dept. 217-039

Address.City

State .

D CRAPS $6.95

D BIO-RYTHM $5.95

D ALL 4 PROGRAMS $19.00Blank CIO Cassettes - Quantity

NAME

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$5.95$4.95

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D Check D Money Order

I □ Check if interested in G.I. Bill information.

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210 BYTE September 1979

Circle 279 on inquiry card.

Complete money back guarantee. No questions. Personal checks accepted. Wetrust you. All shipments made in 10 days.

Circle 101 on inquiry card.

Circle 287 on inquiry card.

# Omikron transforms TRS-80*into a powerful business system.

STANDARD DRIVES 8" Drives give you 5times the speed and 3 times the storage ofyour mini drives! Our system provides astandard Shugart interface so you can useeither your 8" drives or ours. Omikrondrives are enclosed in an attractive metalcabinet, and include a power supply.

SOFTWARE CP/M* is the most popularoperating system for microcomputers. Butmany high-level languages and advancedbusiness programs cannot run with thespecial CP/M* designed exclusively for theTRS-80* The Omikron MAPPER withstandard CP/M* allows you to expand yoursoftware capability to go beyond the fewavailable TRS-80* compatible packages.TRS-80* with MAPPERout-performs systemscosting $1000more

The MAPPER I and MAPPER II are plug-in modules. They don't require any circuitchanges, are easy to install, and they don'tinterfere with the normal operation of yourTRS-80? All your original software, includ-ing Level III BASIC will still run properly.Omikron products require 16KLII BASICand the TRS-80* Expansion Interface.

• • •

MAPPER I is a memory management unitwhich adapts your TRS-80* to run stan-dard CP/M* Versions for both 5" and 8"drives are available. The package includesCP/M* software on 5" or 8" diskette, anddocumentation. 5" unit, $169. 8" unit, withadapter cable, $199.

MAPPER II includes the MAPPER I pack-age plus a disk adapter module whichallows both 5" and 8" drives to run on thesame cable. Drive selection is under soft-ware control to permit easy file transferbetween the drives. With cable, $249.CONVERSION -If you purchase MAP-PER I or II and plan to use only mini-drives, Omikron will transfer CP/M* filesfrom 8" diskette to a 5." This allows you torun software previously available to only8" drive owners. $25 per mini-diskette.DRIVE - 8" drive, $849. Additional drive,$695. WARRANTY- 1 year on boards;90 days on drives. VISA/MasterChargeaccepted. Prepaid orders given top priority.

*CP/M is a TM of Digital

Research. TRS-80 is

a TM of Tandy

Corporation.

PROFESSIONAL

INCOME TAX PROGRAMSFOR TRS-80™

Accountants, lawyers, tax consultants nationwide, prepared over 30,000 1978Federal tax returns using our system.

Displays and fills in Form 1040 and related schedules on the screen, thenprints out the completed forms automatically.

Change your mind? Make an error? Correct a single entry and you have a brandnew form with all re-computations made automatically.

No tax system, running on any computer anywhere, has all the features of ourprofessional system, and yet—

Our base program, which does 1040 and Schedule A costs only $189.95

And! You can add schedules for only $37.95 each, customizing your systemto your requirements.

CONTRACT SERVICES ASSOCIATES

706 SOUTH EUCLID ANAHEIM, CA 92802

TELEPHONE (714) 635-4055

FREE CATALOG AND BROCHURE TO PROFESSIONALS

Circle 82 on inquiry card.

BYTE September 1979 211

Circle 18 on inquiry card.

Circle 327 on inquiry card.

A specially designed SF TACTICAL BATTLE GAME foryour PET, TRS-80 or APPLE Computer.

The man called Sudden Smith watched the five blips onhis screen spread out to meet the enemy. Two freightersconverted into something like battlewagons, powerfulbut slow, and three real cruisers: the most powerful groupof warships ever seen near the Promethean system — exceptfor the Stellar Union fleet opposing them. Everyone wascalling it Starfleet Orion, though it existed for only thisday. It was life or death, and, after the object lesson onthe planet Spring, everyone knew it.

STARFLEET ORION is a complete 2 player game system

• rule book • battle manual • cassette

• ship control sheets • program listings

Includes 2 programs, 22 space ship types, and 12 playtestedscenarios. Game mechanics are extremely simple, but playis exciting, challenging, and rich in detail. Specify PET (8K),TRS-80 (Level II, 16K), or APPLE II (16K& 32K) $19.95.

Ask your local dealer or send your check to:

Automated SimulationsDepartment YP.O. Box 4232Mountain View, CA. 94040

California residents please add 6% sales tax

6800 DEVELOPMENT SOFTWARE

An integrated applications development and execution system.

SDOS

All devices interrupt-driven including typehead. Providesdevice independent, byte addressable random files. Supportsany mixture of floppy or hard disk drives up to 2.5 billion bytes.Sector read-ahead and buffer pool enhance application perfor-mance. Flexible: Currently runs on 7 manufacturers' systems,using 10 different drive/controllers, including mini-floppies andhard disk.

BASIC COMPILER

For speedy business applications. 10 digit BCD; random accessto variable size records; long variable names; formatted out-put; if-then-else; error trapping. Field proven for over 2 years.

EDIT

A powerful text editor with change, delete, replace commands.Automatic display of modification or context changes; macrofacilities for complex or repetitive editing.

ASM

2 pass conditional assembler; 32 character labels; symbol tabledump and cross-reference; error cross-reference; extensivearithmetic and listing control.

IOB

Single-step, multiple, real time breakpoints; memory dump;multiple display modes. No special hardware needed.

Over 500 pages of documentation to match this proven soft-ware.

Complete package: $760.00

Also (not including SDOS) available for SWTP, Exorcisor, SSBand MSI DOS.

Write for free catalogue. Sizable distributor discounts.

SOFTWARE DYNAMICS

2111 W. Crescent Avenue, Suite G

Anaheim, CA 92B04

(714)635-4760

TRS-80 disk software

DISKETTE DATA BASE IDM-III 32K $49

You can use it to maintain a data base & produce reports without anyprogramming. Define tile parameters & report formats on-line. Features keyrandom access, multi-keys, sort, select, field arith, audit log. Almost use upall 32K.

ACCOUNT manage client accounts & account receivable. Automatic billing &transaction recording. Print invoices and reports. 32K req. $59.

WORD PROCESSOR 16K $39

Our WORD-HI is the first word processor specifically designed for TRS-80that uses disk storage for text. Written in BASIC. No special hardware andtext limit. Use for letters, manuals & reports.

MAILING LIST 16K $35

It lets you maintain data base and produce reports & labels sorted in anyfield. Random access. 2-digit selection code used.

INVENTORY 16K $39

While others use inefficient sequential file, we use 9-digit alphanumeric keyfor fast on-line random access. Record has key, description, level, safetylevel, order ami, unit cost & price, annual usage, location and vendor code.Reports give order info, performance summary, etc.

KEY RANDOM-ACCESS UTIL16K $19

Lets you access a record by specifying a key. Features hashing, blocking,buffering technique, auto I/O error retry, etc.

MICRO ARCHITECT

96 Dothan St.Arlington, MA 02174

'TINY' PASCALtor TRS-80®

& NORTH STAR®

Now you too can have Pascal! The Chung/Yuen 'Tiny' Pascal hasbeen specially designed for TRS-80 & North Star owners. The fullpower & elegance of 'Tiny' Pascal is at your command. Programswritten in 'Tiny' Pascal run at least 4 times faster than the sameprogram in BASIC! 'Tiny' Pascal is also a great way to learnPascal Programming, & fun too.

The minimum system requirements are: Level II, 16K for TRS-80,(no disk required) & 24K for North Star (specify density).

SOURCE TOO!But most important, you also get source to 'Tiny' Pascal writtenin Pascal with each purchase! You can even compile the com-piler! (Requires 36K for North Star systems, & 32K, Level II forTRS-80). You can customize your own version, or just use it theway it is.

'Tiny' Pascal is a subset of Standard Pascal & includes.RECURSIVE PROCEDURE/FUNCTION, IF-THEN-ELSE,REPEAT/UNTIL, 'PEEK & POKE', WHILE, CASE, & MORE!(Plus full graphics for TRS-80 as well)Also you can save & load programs.You get all this & more, plus a user's manual for $40.00.

available from:

/mm/on

P.O. Box 1628Champaign, IL 61820(217) 344-7596^ All orders pre-paid, Illinois residents add 5% sales tax

212 BYTE September 1979

Circle 214 on inquiry card.

Circle 359 on inquiry card.

Circle 102 on inquiry card.

BYTE

BACK ISSUES

FOR SALE

The following issues are available:

1976: July

1977: March, May thru December

1978: February, October, December

1979: January thru August

Cover price for all issues thru August 1977 is

$1.50 plus $.25 postage and handling ($3.50 total foreign).

September '77 thru '79 issues are $2.00 plus $.50

postage and handling ($4.00 total foreign).

Send requests with payment to:

BYTE Magazine

70 Main St, Peterborough NH 03458

Attn: Back Issues

KITE

)[

Good Buys From Disks, Etc.

VerbatimMINI-DISKS

10 for $29.00or 3 for $10.00

New! Verbatim Digital QualityCassettes For Personal Computers

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2 for $5.45

1

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Storage Cases

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MasterCharge, ^mm m p Q Box 327 cChicks OK. Disks, Etc. Center Valley,No COD's.

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R2 I/O

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16 K RAM

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ELECTRONIC CONTROL TECHNOLOGY (2od bsg-boso

Circle 120 on inquiry card.

BYTE September 1979 213

What's New?

Low Cost Computer Assisted Instruction

APPILOT language is an Apple II ver-sion of the standard computer assistedinstruction (CAI) language, PILOT. Usinglesson files created by the APPILOT pro-gram editor, APPILOT creates multi-media learning experiences with text,graphics and sound. The student can in-teract with APPILOT using both numbersand words which APPILOT recognizes asstudent input.

APPILOT conforms closely to the pro-posed common PILOT standard, but itincorporates features that fully use thecapabilities of the Apple II computer.Among these features are color graphicscommands, a musical minilanguage, anddisk commands for lesson segmentationwhich give an effective lesson size up to90 K bytes. APPILOT also links to the Ap-ple's integer BASIC to allow full calcu-lation capacities.

APPN OT is available on tape anddisk, and is offered on Super Load tapesand for those Apple owners who wish torun prewritten APPILOT lessons. For$17.95 the user can execute APPILOTlessons on a 16 K byte Apple, using onlytape storage. Included on the tape is theinterpreter and a demonstration lessonabout APPILOT. Also provided is adocumentation manual for runningAPPILOT and for linking it with theMUSE APPEN-I Text Editor, which maybe used for creating and editingAPPILOT lessons.

For institutions that wish to write aswell as use APPILOT lessons, the

CP/M Text Editor

ED-80 is a text editor designed torun under CP/M and derivative operatingsystems on 8080, 8085, and Z-80 diskbased systems. A user's manual of over60 pages describes both implementationand usage. ED-80 has a simple commandstructure patterned after the Universityof Maryland's editor for UNIVAC 1100s.Over 50 commands are provided, includ-ing forward or backward locate, change,and find commands; insert, delete,append, print, list, macro, case, scale,tabset, and window commands; and getand put commands for copying, moving,merging, and duplicating edit files andprogram libraries. An internal locationcounter is maintained for dis-playing with text, prompting for userinput, and for line positioning.

ED-80 provides a window approachto text editing that is not hardware

APPILOT Edu-Disk converts a 32 K byteApple with disk into a complete CAIsystem. The user can develop lessons,store them on disk, and run them withthe APPILOT interpreter. The Edu-Diskcomes with interactive lessons that in-struct the user on all aspects of theAPPILOT CAI development system. TheAPPILOT Edu-Disk is being offered for$49.95 which includes a detaileddocumentation manual. For further in-formation, contact MUSE, 7112 Dar-lington Dr, Baltimore MD 21234.Circle 565 on inquiry card.

Machine Language Programs for thePET Computer

The SYS7171 and the SYS8181 are twonew machine language programs for thePET 2001 computer. SYS7171 is amachine language monitor which allowsa programmer or PET user to program inmachine language, or in BASIC, withoutdestruction of the monitor once it isloaded. Programs may be saved, loadedor rewritten yet SYS7171 remains coresi-dent and undisturbed.

SYS8181 is a machine language re-numbering program which requires only1 K byte of programmable memory forits operation. After it is loaded, the usercan load a BASIC program and it will berenumbered in seconds.

SYS7171 sells for $29.71 and SYS8181is priced at $18.71. For further informa-tion, contact National Artificial In-telligence Laboratory, POB F, Mobile AL36601.

Circle 566 on inquiry card.

Word Processing Software System

Autoscribe is a professional wordprocessing system designed for thebusiness world. With Autoscribe, typedtext appears on a video terminal screenas it will be printed, and corrections,deletions or revisions can be made inseconds. The finished document is typedat hundreds of words per minute.Letters, contracts and other documentscan be produced quickly on single pageor continuous form print-out. The ori-ginal data is recorded and saved on theuser disk. Documents can be retrievedinstantly and reprinted as needed. Nocomputer language is needed. All in-structions are in English. Autoscribesoftware operates on Z-80 and 8080 sys-tems utilizing North Star disk, a Sorocor Hazel tine terminal and a letter qualityprinter. For further information contactMicroAge Wholesale, 1425 W 12th Place,Tempe AZ 85281.

Circle 567 on inquiry card.

dependent. Users may examine and editdata through a one line window as itis moved through the edit file. A windowcommand allows instantaneous fullscreen displays of both the current lineand surrounding lines, with forwardand backward scrolling.

Compatible with existing CP/M editfiles, ED-80 is available on an 8-inchsingle density disk for $71. For furtherinformation contact Software Develop-ment and Training Inc, POB 4511,Huntsville AL 35802.

Circle 568 on inquiry card.

16-Digit Scientific Subroutine Packagefor Microsoft Extended and Disk BASICInterpreters

DPFUN is a comprehensive 16-digitprecision scientific subroutine packagewritten for Microsoft extended and diskBASIC intepreters, including TRS-80Level II BASIC. The 1 3 double-precisionexponential, logarithmic, trigonometric,and inverse trigonometric functions pro-vide a valuable utility for engineeringand scientific applications. DPFUN usestruncated continued fraction algorithmsthat result in easily entered code, fastexecution, and full exploitation of theprecision that is available in 64-bitbinary floating-point notation. The com-plete set of subroutines occupies approxi-mately 2.5 K bytes.

The DPFUN source code only isavailable for $10 postpaid. For furtherinformation contact Miken Optical Co,53 Abbett Av, Morristown N J 07960.Circle 569 on inquiry card.

Elementary Math Tapes for TRS-80

The Microcomputer Mathematics Pro-gram K-8 consists of a set of tapes fordrill, practice and tutorial in addition,subtraction, multiplication, division,fractions, numeration and decimals forkindergarten through 8th grade. Thetapes are programmed for use on aRadio Shack Level II BASIC TRS-80microcomputer and 16 K bytes modifiedmemory. The teacher's manual gives anoverview of the program, suggests waysto use the program, correlates the skillsto selected mathematics texts, and pro-vides suggestions for individualizingmath instruction. One set of microcom-puter Mathematics Program K-8 tapes in-cluding the teacher's manual is $995. Forfurther information, contact Foundationfor Quality Education Inc, 802 Mer-chants State Bank Building, 5217 RossAv, Dallas TX 75206.

Circle 570 on inquiry card.

214 September 1979 © BYTE Publications Inc

Circle 12 on inquiry card.

A COMPLETELY REFURBISHED "SELECTRIC" ASCIITERMINAL FOR THE SMALL BUSINESSMAN OR SERIOUS HOBBYIST.

The AJ 841 I/O terminal.Now available from dealers nationwide.

Demand for our AJ 841 I/O computer terminal hasbeen great. And now it's getting even greater. So call yourlocal computer shop dealer right away. Supply is limited!You may never have another opportunity like this one to buyyour own professional terminal.

The A J 841 features:

■ Choice of serial RS 232 or parallel interface

• ASCII code

• 14.9 cps printout

• High quality Selectric printing

• Heavy-duty Selectric mechanism

• Off-line use as typewriter

• Documentation included

• 30-day warranty on parts and labor (details availableon request)

Call toll-free now

For location of your nearest AJ dealer, call toll-free:

800/538-9721

California residents call 408/263-8520.

l«

oV.*°*

'd

from Computer Headware. . . the Self-Indexing Query System

for your Apple II, North Star, or CP/M machine

Distributed by:

. Information Unlimited / 219-924-3522P.O. Box 8372. Merrillville, Indiana 46410

■ Lifeboat Associates / 212-580-0082 (CP/M model only)2248 Broadway, Suite 34, New York City 10024

. Structured Systems Group, Inc. / 415-547-15675208 Claremont Avenue, Oakland, California 94618

BYTE September 1979 215

What's New?

MISCELLANEOUS

Computer Communication atYour Fingertips

VuePoint is a touch input displaypanel that measures only V/x inchesthick. Vuepoint's 12 line by 40 characterflat panel also provides a unique touchinput capability. This approach permitsefficient and speedy operator inter-action using menu-driven displays. Vue-point's microprocessor based controllerprovides all standard smart videofeatures plus the following: touchresponse in matrix or screen echo modes,multiple display buffers, and alternatecharacter sets. Communication is bystandard 300-19200 bps asynchronousRS-232 protocol. Options include wall orrack mount, auxiliary printer, and 128character ASCII keyboard. Vuepoint ispriced at $3500. For further information,contact General Digital Corp, 700 Burn-side Av, E Hartford CT 06108.Circle 571 on inquiry card.

APL/Z-80 Release 2.0

Vanguard Systems Corp, 6812 SanPedro, San Antonio TX 78216 has an-nounced the release of version 2.0 ofAPL/Z-80, an APL interpreter for Z-80based microcomputers. APL/Z-80 in-cludes the following features: dynamicexecution of system commands; serialprinter support; shared variables; aux-ilary processor for I/O (input/output)ports which allows complete devicecontrol using defined APL functions forany device interfaced to the Z-80 I/Oport; and auxilary processor implemen-tation of a file system featuring a dir-ectly indexable file having variable

length records, each of which can be anAPL array of arbitrary type, shape,and size (up to available workspace).

A workspace containing definedAPL/Z-80 functions, implementing eachof the primitive functions not presentin this version of APL/Z-80, is distri-buted with each system. The hardwarerequired is a Z-80 processor, a disk drive,and either serial ASCII APL consoleterminal or ASCII keyboard and videodisplay board compatible with theVector Graphic Flashwriter or ProcessorTechnology VDM-1.

The end user license for use on asingle processor is $350.

Circle 572 on inquiry card.

Distributed Computer System Basedon Personal Computers

Cluster/One is a distributed pro-cessing alternative to BASIC timesharing.The central Cluster/One unit (the Queen)connects to 15 personal microcomputers(the Drones), via a high-speed paralleldata bus (the Clusterbus). An optionalfeature provides support for an addi-tional 15 Drones. Currently supportedas Drone stations are the Apple II,Commodore PET 2001-8, and TRS-80.

Programs and data files can be sharedamong the users of Cluster/One. Theyare stored on two IBM compatible eightinch floppy disks. Each disk holds up to315 K bytes of data. Disk data transferrate is 250 K bits per second, managedby a large scale integration floppy diskcontroller chip. All data transfers arccyclic redundancy checked (CRC) anddisk writes are automatically verified.Data is transmitted to each Drone sta-tion in packets, with individual errorchecking. Typical system response timefor program loading is two seconds.

Cluster/One commands are quitesimilar to their counterpart cassettetape commands. Disk commands may beimbedded in user programs, permittingmenu-driven program loading or chain-ing.

Cluster/One comes with a full set ofutility programs for system maintenanceand backup, along with separate doc-umentation for the end users. Pricesbegin at $45 00 and vary with the parti-cular configuration and options selected.For further information, contact NestarSystems Inc, 810 Garland Dr, Palo AltoCA 94303.

Circle 573 on inquiry card.

Where Do New Products Come From?

The information printed in thenew products pages of BYTE isobtained from "new product" or"press release" copy sent by thepromoters of new products. If inour judgment the informationmight be of interest to the per-sonal computing experimentersand homebrewers who readBYTE, we print it in some form.We openly solicit releases andphotos from manufacturers andsuppliers to this marketplace. Theinformation is printed more orless as a first in first out queue,subject to occasional prioritymodifications. While we wouldnot knowingly print untrue orinaccurate data, or data fromunreliable companies, our capa-city to evaluate the productsand companies appearing in the"What's New?" feature is neces-sarily limited. We therefore can-not be responsible for productquality or company performance.

Heat Scalable Cassette Holder

This cassette holder, designatedPocketray, will hold a cassette securelywith the title visible. Cassettes are fullyprotected on three sides. There are 12Pocketrays to a sheet which is perforatedvertically and horizontally. These maybe snapped apart into single units or inany multiple to fit the most creative con-figuration. Made of PVC, these cassetteholders are easily heat sealed to anyvinyl material, with a minimum of tool-ing. Samples, pricing, and literature areavailable from Charles Leonard Inc,79-11 Cooper Av, Clendale NY 11227.Circle 574 on inquiry card.

216 September 1979 © BYTE Publications Inc

FLOPPY DISKREPAIR

• PerSci and Shugart

• Quick turnaround

• Factory trained onPerSci

TKc:';;;;i;!lV>:;;;::::*T^,T :^t> "^'W

COMPUTER SERVICE CENTER

7501 Sunset Blud

Hollywood CA 90046

213-851-2226

Circle 68 on inquiry card.

GET CONNECTED

Connect your S-100 BUS orTRS-80 system to the telephonenetwork and turn it into a terminal.The ^-Phone© is absolutely allyou need — it's not just a modem,not just a controller.

Just plug the /i-Phone© into yourprocessor and plug it's cable into astandard modular telephone walljack and you're connected.

The fi-Phone© is BELL 103 com-patible and F.C.C. registered.

Another Fine Idea From

I.D.E.A.

850 Lexington St.

Waltham, MA 02154

617-893-1368

Circle 178 on inquiry card.

BASIC/FOUR COMPUTERMODEL 350

Perfect for small to mediumsized business applications.Model 350 CPU, 4.2 MbDisc Drive, Video Display Ter-minal, 160 cps Printer, and 6Disc Cartridges. Under con-tinuous factory maintenance.Full system ready to go$11,000.

Contact:Carl Egetter (714) 979-9013THERMAX SYSTEMS, INC.

3185 "A" AIRWAY AVECOSTA MESA, CA 92626

Come Help UsCelebrate The Child

St. Jude Children's ResearchHospital continues its search forlife-saving knowledge aboutcatastrophic childhood disease.And this search continuesbecause people care. There'sno charge to patients or theirfamilies,once admitted to itsresearch studies by physicianreferral. The cost of drugs,equipment, and researchprograms is met primarilyby public contributions. Helpus celebrate the child by send-ing your fax-deductible checkor request for further informa-tion to St. Jude Children's^ _ Research Hospital,k A™ 539 Lane Ave.,ifej Memphis, TN 36105.

Don't Forget!

Our New 4K Byte Non-VolatileMemory Boards Won't Let You!

• 30 days minimum guaranteeddata retention

• Ultra low power 450 NSECstatic CMOS RAM IC's

• On-board regulator, powermonitor and battery

• S-100 bus compatible

Assembled and Tested$395.00

Remember...

to send for details!

1395 Golf StreetDayton, Ohio 45432

Circle 88 on inquiry card.

TRS-80 USERS

Three Diskless TRS-80 Programs

- Telephone/Address/Mailing list pro-gram - sorts by name or zip code.Retrieves telephone § from name andvisa versa. Access time is under 2seconds, over 100 listings, Level II 16K

-$30.00

- Checkbook program - hard electroniccopy, easily accessable. 170 listings,Level II16K -$30.00

- Mandalas for the Cybernectic Age I & II-amazing graphic programs, better thanTV - lasts hours without repeating orcommercials. 2 sets of four interweavingdesigns, Level I or II 4K RAM

- $30.00Introductory offer - All 3 for $75.00Loweco provides complete supportCatalog $2.00

LOWECO COMPUTOR

1803 RODNEY

LOS ANGELES CA 90027

213-660-7530

6% TAX IN CALIFORNIAMoney Order, Cashier Check Speeds Delivery

TRS-80, PET,APPLE,

SORCERER

Hardware/SoftwareSystems

Available now:

■ HAMINTERFACE-including themost sophisticated RTTY systemsmoney can buy.

■ Baudot and ASCI I printerinterfaces.

M Electra Sketch' .ANIMATIONGRAPHICS Compiler

Write or call for free catalog

>VWCROTRONICS,inc.

P.O. Box 518 (a) Keyes, CA 95328(209) 634-8888 / 667-2888 (R) (S)

We are experiencing telephone difficulties,please keep trying.

Circle 206 on inquiry card.

EXCELLENT BUY:USED CENTRONIC PRINTERS

Model 703 $1495.

Model 588 S 895.

COMPLETE

TIME SHARING

AND

IN-HOUSE

SYSTEMS AVAILABLE

Texas Instrument3n Teletypem£ XeroxIntertecAltos

Ohio ScientificExidyCentronics

Circle 74 on inquiry card.

A Messageto our Subscribers

From time to time we make the BYTEsubscriber list available to other com-panies who wish to send our subscriberspromotional material. We take great careto screen these companies, choosingonly those who are reputable, and whoseproducts, services, or information wefeel would be of interest to you.

While we believe the distribution of thisinformation is of benefit to oursubscribers, we firmly respect thewishes of any subscriber who does notwant to receive such promotionalliterature. Should you wish to restrict theuse of your name, simply send your re-quest to

BYTE Publications Inc

Att: Circulation Department

70 Main St

Peterborough NH 03458

Thank you.

Circle 367 on inquiry card.

Circle 207 on inquiry card.

Wtisfs New?

SYSTEMS and MEMORY

New Word Processing System Also Supports Data Processing Applications

A video based word processing sys-tem capable of handling data processingapplications has been introduced by

Vector Graphic Inc, 31364 Via Colinas,Westlake Village CA 91361. The newsystem, called Memorite 2, incorporates

the firm's Z80 based MZ microcom-puter with 630 K bytes of disk capacity,their Mindless Terminal, and the QumeSprint 5, 55 cps printer. For wordprocessing applications, Memorite 2 withdual Micropolis floppy disk drivesfeatures advanced text preparation, edit,and delete capabilities. It offers auto-matic letter printing from memory withfull formatting techniques such as under-lining, indentation, automatic marginsand variable line and character spacing.The system also performs mass mailings,which allow letters to be merged withaddress lists. Its memory is resident onprogrammable read-only memory, sousers need only type after a "power upand proceed" function.

As a data processor, Memorite 2 iscapable of performing standard account-ing tasks and custom applications inbusiness BASIC for small firms ordepartments of large companies. Scien-tific calculations are also available fortechnical environments.

The price for the Memorite 2 is$8,950.

Circle 575 on inquiry card.

CATCH THE

S-100INC.

BUS!

Vector Graphic 16KAssembled Fast MemoryBoard

Imsai "8080" Kit completew/Front Panel

Computime CT100 Clock,Calendar & Calculator Kit

S-100's Three Ring Binder

w/Ten Vinyl Jackets for 51AMini Floppies (HoldsTwenty Diskettes PlusDirectory Pocket)

LISTPRICE

OUR

SPECIAL

CASH

PRICE

485.00 350.00

750.00 625.00

199.00 170.00

13.00 7.00

Imsai 80/15 Kit w/8085 CPU 799.00 625.00

We carry all major lines such as

S.D. Systems. Cromemco. IMSAI, Vector Graphic. North Star. Sanyo. ECT.

TEI. GorJIioul. Thinker Toys. Hazeltine. IMC

For a special cash price telephone us.

Subject to Available Quantities • Prices Quoted Include Cash DiscountsShipping & Insurance Extra.

Bus.Address.

Interface.

.S-JQD,inc.

7 White PlaceClark, N.J. 07066201-382-1318

Non-Volatile Memory Board

The E4K EAROM Memory Board pro-vides a Multibus compatible nonvolatilememory of up to 4 K words by 8-bitcapacity. The memory contents are elec-trically alterable under computer con-trol, permitting it to function as a pro-grammable memory but with the advan-tage of long term unpowered data reten-tion. Either word or block erasure ispossible. Operating software listings areprovided with the board. Typical appli-cations include remote data acquisitionsystems, numerical control systems, pro-cess controllers, storage of manuallyentered constants and telephone numberstorage.

The prices for the E4K EAROMMemory Board start at $420. For furtherinformation, contact Schneider Instru-ment Co, 8115 Camargo Rd, Madeira OH45243.

Circle 576 on inquiry card.

218 September 1979 © BYTE Publications lnc

Circle 316 on inquiry card.

HE MM-103 DA TA MODEM

AND COMMUNICA TIONS ADAPTER

FCC APPROVED

S-100 bus compatible

Both the modem and telephone system interface areFCC approved, accomplishing all the required protectivefunctions with a miniaturized, proprietary protectivecoupler.

WARRANTY

One year limited warranty. Ten-day unconditionalreturn privilege. Minimal cost, 24-hour exchange policyfor units not in warranty.

HIGH QUALITY

-50 dBm sensitivity. Autoanswer. Auto originate. Autodialer with computer-controlled dial rate. 61 to 300 baud(anywhere over the long-distance telephone network),rate selection under computer control. Flexible, soft-ware-controlled, maskable interrupt system.

ASSEMBLED & TESTED

Not a kit! (FCC registration prohibits kits)

LOW PRICE-S359.95- Bfi/BSIR,

plus shipping& handling

Potomac Micro-Magic, Inc

Write for brochure:First Lincolnia Bldg., Suite B14810 Beauregard St.Alexandria, Va. 22312

Call for further information:

VOICE: (703) 750-3727

MODEM: (703) 750-0930 (300 baud)

DATA TERMINAL EQUIPMENT FROM MICROMAIL

T.I.810printer $1,695.°°

S0R0C IQ 120

$795.°°

• RS 232C, upper/lower case, fullASCII

• Numeric keypad, protected fields

• Cursor keys plus addressable cur-sor

• Auxiliary extension port

LA34 DECwriter IV

M.199"

Upper/lower case, 9x7 dot matrix

10, 12, 13.2, 16.5 characters/inch

2, 3, 4, 6, 8 or 12 lines/inch

22"W x 7"H x 15Vi"D, 25 lbs.

110 or 300 baud, RS 232C serial

ASCII

Friction feed, paper width to 15"

S0R0CIQ 140 * 1,250.°°

• RS 232C and 20mA current loop

• Extensive editing features

• 25th line terminal status display

• 16 function keys (32 with shift)

Newfrom DIABLO

DIABL01640 *2,690.°°Receive-only $ 2,331.00

High-quality daisywheel printing at45 cps.

DIABLO 1650 5 2,779.°°Receive-only * 2,419.°°

Metal daisywheel printing at 40 cps.

Includes upper/lower case150 characters per secondRS 232C serial interfaceAdjustable forms tractor

NEC Spinwriter

Call or write for prices

To Order: Send certified check (personal or company checks requiretwo weeks to clear) including handling* and 6% sales tax if deliveredwithin California.

'Handling: Less than $2,000, add 2%; over $2,000, add 1%. Everythingshipped freight collect in factory cartons with manufacturer's warranty.

cKHCRQklfllL

MICROMAIL • BOX 3297 • SANTA ANA, CA 92703(714) 731-4338

Circle 223 on inquiry card.

BYTE September 1979 219

Circle 227 on inquiry card.

Paul McCoy Enterprises, Inc.

Software

TM

NARKLE™

The NAME, ADDRESS, REFERENCE, KEYWORD, LETTER, ENVELOPE SYSTEM.

DATA FILE

NARKLE ™ is an interactive, menu-operated system that allows the creation,maintenance, up-date, delete, etc, of a mailing information file.

Using the 100 reference fields you can store data about each client and alsouse this data as a means of automatically building smaller more specific files.Also, you can list files, view individual records by name or record number,and so much more.

LETTER

Using the NARKLE data file and your text editor, NARKLE will create hand-crafted personalized letters completely automatically. It features automaticdata file name insertions in the inside address, salutation, and the body ofthe letter; either first name or title last name. Up to 25 ^keywords" can beused, and so much more.

NARKLE is the most polite data system on the market today, easily operatedby secretarial personnel with a few hours' instruction.NARKLE is sold on diskettes and includes a 43-page operator's manual.

Paul McCoy Enterprises, Inc.™

300 E. 30th Street, Austin, Texas 78705Phone: (512) 476-1700

Hardware required for NARKLE and XTABFREQ: 8080 or Z-80 BasedMicrocomputer/48k of memory/CP/M or similar software/CBASIC, Diskdrive(s) and interface, terminal and printer.

XTABFREQ™

The CROSSTABULATION, FREQUENCY, STATISTICS, ENTRY SYSTEM.

XTABFREQ is a completely interactive system which secretarial personnelshould be able to operate with only a few hours of instruction.

The crosstabulation routine can operate in two or more dimensions,generating cell count, cell row and column %, as well as cell % of total table.The routine delivers Chi-Square, Degrees of Freedom, Lambdas, UncertaintyCoefficients, Etas, Kendall's Tau B and Tau C, Gammas and Somer's D. TheSPSS'" user will find XTABFREQ NOT TO BE A COMPROMISE but much moreconvenient and versitile.

FREQUENCY

Besides for Absolute Frequency the routine generates Adjusted, Relative andCumulative Frequency. Also a code and symbol for Weighting can be usedwith the Raw Count.

You also get the Mean, Mode, Kurtosis, Minimum, Maximum, Range,Standard Error, Standard Deviation, Skewness, Median, and Variance.

REFENTRY

Both the Crosstabulation and the Frequency Routine utilize the very powerfuldata entry and management routine, REFENTRY™. This routine lets you easilybuild, examine, store on diskettes, manipulate, and extract files for yourXTABFREQ JOBS. XTABFREQ will also accept NARKLE™ File interactively.

With XTABFREQ you can predict tomorrow without waiting for punchcards.XTABFREQ is sold on diskettes with a 37-page operator's manual.

Send $175 for Narkle and $295 for XTABFREQ. Manuals are available at$10 each. Dealer inquiries welcome.

SPSS™ is a copyright of McGraw-Hill, Inc.

220 BYTE September 1979

Circle 291 on inquiry card.

Circle 79 on inquiry card.

Circle 91 on inquiry card.

PET WORD PROCESSOR

This program permits composing and printing letters,flyers, advertisements, manuscripts, etc., using theCOMMODORE PET and a printer.Script directives include line length, left margin, cen-tering, and skip. Edit commands allow the user toinsert lines, delete lines, move lines and paragraphs,change strings, save onto cassette, load from cassette,move up, move down, print and type.The CmC Word Processor Program addresses an RS-232 printer through a CmC printer adapter.The CmC Word Processor program is available for$29.50. Add $1.00 for postage and handling per order.

Order direct or contact your local computer store.

CONNECTICUT microCOMPUTER

150POCONO ROAD

BROOKFIELD, CONNECTICUT06804

(203) 775-9659

TLX: 7104560052

NO FRILLS! NO GIMMICKS! JUST GREAT

DISCOUNTS

MAIL ORDER ONLY

HAZELTINE

1400 $679.00

1500 995.00

Mod 1 1495.00

CENTRONICS

779-1 954.00

779-2 995.00

700-2 . 1350.00

761 KSR tractor 1595.00

703 tractor 2195.00

MicroPrinter 395.00

NORTHSTAR

Horizon I assembled. . 1629.00

kit 1339.00

Horizon II assembled . 1999.00

kit 1599.00

Disk System 589.00

TELETYPE

Mod 43 995.00

DIGITAL SYSTEMS

Computer $4345.00

Double DensityDual Drive 2433.00

IMSAI

VDP 80/1000 $5895.00

VDP44 4195.00

16K Memory assem.. 399.00PCS 80/15 679.00

15% oil on all other Imsai products

DEC

LA34 1149.00

CROMEMCO

System III $1000 ott . 4990.00

10% off on all otherCromemco products

TEXAS INSTRUMENTS810 Printer 1595.00

Mosl items in stock for immediate delivery. Factory-fresh, sealed cartons.

DATA DISCOUNT CENTER p.o.box-ioo

135-53 Northern Blvd., Flushing, New York 11354, 212/465-6609

N.Y.S. residents add appropriate Sales Tax. Shipping FOB N.Y.I BankAmericard, Master Charge add 3%. COD orders require 25% deposit

CP/M

®

LOW-COST

MICROCOMPUTER

SOFTWARE

CP/M® OPERATING SYSTEM:

• Includes Editor, Assembler, Debugger and Utilities.

• Standard version for 8080, Z80, or Intel MDS(other versions available.)

• For IBM-compatible floppy discs.

• $100-Diskette and Documentation.

• $25-Documentation (Set of 6 manuals) only.

MAC™ MACRO ASSEMBLER:

• Compatible with new Intel macro standard.

• Complete guide to macro applications.

• $90-Diskette and Manual.SID™ SYMBOLIC DEBUGGER:

• Symbolic memory reference.

• Built-in assembler/disassembler.

• S75-Diskette and Manual.TEX™ TEXT FORMATTER:

• Powerful text formatting capabilities.

• Text prepared using CP/M Editor.

• $75-Diskette and Manual.DESPOOL™:

• Background print utility.

• Use with CP/M (version 1.4)

• $50. Diskette and Manual.

1 DIGJTflL RESEARCH

P.O. Box 579 • Pacific Grove, California 93950(408) 649-3896

®

UNCOMPROMISED

QUALITY AND

PERFORMANCE IN A

JOYSTICK FOR YOUR

APPLE II*

Available now fromyour local dealer

$65

I or by mail from

Whether for technical/graphics or a more realisticgame of Star Wars, you' 11 love this precision gimballedjoystick with self-centering action and unique capacitiveswitch that activates with only a touch of the control shaft.Front panel accessible X and Y axis trimmers and inputpushbutton are featured on the PAIA/APPLE n Joystick.Plug compatible with the APPLE II game controller.

Distributed by: High Technology, Inc., Oklahoma City- Dealer Inquiries Invited -

Send the PAIA/APPLE/n Joystick Controller □ $65. 00 plus

$1. 50 postage enclosed. □ Charge VISA MC

Card No. Expiration Date:

address,city

state

zip

ELECTRONICS DEPT. 9-8.1020W. WIISHIRE BLVD.. OKLAHOMA CITY, OK 73116

Circle 95 on inquiry card.

Circle 297 on inquiry card.

BYTE September 1979 221

Circle 93 on inquiry card.

Circle 211 on inquiry card.

25 START-AT-HOMECOMPUTER BUSINESSES

In "Low Capital, StartupComputer Businesses"

CONSULTING • PROGRAMMING • MICRO COMPUTEROPPORTUNITIES • SOFTWARE PACKAGES • FREELANCEWRITING • SEMINARS • TAPE/DISC CLEANING • FIELDSERVICE • SYSTEMS HOUSES • LEASING • SUPPLIES •PUBLISHING • HARDWARE DISTRIBUTORS • SALESAGENCIES • USED COMPUTERS • FINDER'S FEES •SCRAP COMPONENTS • AND MORE .

Plus — ideas on moonlighting, goingfull-time, image building, revenuebuilding, bidding, contracts, marketing,professionalism, and more. No careertool like it. Order now — if not completelysatisfied, return within 30 days for fullimmediate refund.

• 8% x 11 ringbound • 156 pp. • $20.00Phone Orders 901-761-9090

!

DATASEARCH

incorporated4954 William Arnold Road, Dept. B, Memphis, TN 38117Rush my copy of "Low Capital Startup Computer Businesses" at $20.

NAME/COMPANYADDRESS

CITY/STATE/ZIP

□ Check Enclosed

□ VISA □ Master Charge Exp. Date

KEYED FILE MANAGEMENT

Put data at your fingertips.. .easily accessed, displayed andupdated by key. Designed to meet all of your data managementneeds, MAGSAM'" allows you to quickly implement sophisticatedkeyed file structures through simple CBASIC statements.Standard MAGSAM'" features include record retrieval with randomby key. sequential by key. and generic ("wild card") search, andcomplete compatibility with all CBASIC file facilities. EachMAGSAM'" Package includes the MAGSAM'" file manager.MAGSAMX'" tutorial program, MAGSAMD'" file dump utility. UserGuide, Reference Card, and one year update service.Select the version of MAGSAM'" that meets your requirements. Allversions of MAGSAM'" are completely upward compatible andmay be upgraded at any time for the price difference.

• MAGSAM III™ — Most advanced version. Multiple Key support(any number of keys), and Record and Key Deletion with automaticreclamation of disk space $145t

• MAGSAM II'" — Single Key support with full Deletecapability S99t

• MAGSAM I'" — Entry level version. Single Key support withoutDelete capability S75t

• User Guide only - comprehensive tutorial and reference

manual $15

Available for 8" soft sector. Micropolis, and TRS-80 disk formats.Requires CP/M- or derivative and CBASIC. Distributed as CBASICsubroutines in source form.

Visa and Masterchagre welcome. Dealer and OEM inquiriesinvited

RflMS)

MICRO APPLICATIONS GROUP

7300CALDUS AVENUEVAN NUYS. CA 91406

' Trademark of Digital Research t Single site license

SOFTWARE TOOLS

■ C compilers and cross-compilers forPDP-11's, LSI-11's, 8080's and Z/80's, withcomplete runtime library. The full lan-guage is supported with efficient codegeneration.

■ Interface libraries giving access to allsystem directives for UNIXf RT-11,RSX-11M, RSTS/E, IAS, CP/M, CDOS andISIS-II.

■ A-Natural narrative assembler for 8080'sand Z/80's with librarian and linking loader.

■ Over 75 installations in less than sixmonths.

^UNIX is a trademark of Bell Laboratories.

Continuing maintenance and training available. Anaffordable alternative to Assembler, Fortran or Pascal,for as little as $500 per compiler binary license.Catalogue and references available upon request.Write to ^ 1x1

whitesmiths, Ltd.

127 East 59th Street -NewYork NY10022- 212 799-1200

WELL,

BYTE MA BELL!

TRS-80®

Software-Level I & II,4k & 16k

Have your TRS-80® computer dial thetelephone■ Dial 20 phone numbers, accessedby a single letter code ■ Operates with dial &pushbutton phones ■ Requires a simpleinterface using $4 worth of parts from RadioShack" No internal connections are made tothe TRS-80® ■ The program is supplied oncassette tape, with complete instructions ■(Specify Level I or II with order)

TRS-80" is a registered trademark ofTandy Corporation

Write to: Software Exchange2681 PeterboroW. Bloomfield, Mi. 48033,

222 BYTE September 1979

Circle 388 on inquiry card.

Circle 332 on inquiry card.

Creative Software Introduces: Programs & Products for the TRS-80 (16K level II)

NEW! A supm JOYSTICK interface Un \U TRS-80!

Three sockets allow you to use one I am liild" ur Iwo Atari*'"joystickswith no modilu alions to the I'RS-80 Joystick interlace with Iwo

Jos/slicks lhain luld'" or Ai

$65.00$12.50

Household Finance I & II

$15.00

P.ut 1: Inputs data on each household expenditure: lisis. .ultls. updates,changes or deletes previously input items. Wines data In cassette tape.Part II: Reads data tape. Provides monthly and yearly summaries ol

liii.im i.il data, simile <ategury summaries, and graphs .i upending ptolile

ALSO: New Programs for the PET:

PET Word Processor $75.00

Complete word processing capabilities including uppet lowei case,

string search, siring change .aid many other lealures lound on cummenial word processors. Package includes both text editoi andFormatter and requires 16K or H2K PET.

PET Space War II $10.00

Fantastic real time action! You .ire in complete control ol the Entetprise as you lend off aliens lo search the universe loi colonizublcplanets. Requires the Creative Software single joystick lot the PET.

Household Utility 1 $12.00

(Ini'ludfb CiliMulai, Loans and Buy or Rem Programs)

Household Utility 2

$12.00

Atnoi li/alion and C

Many olhei Creative Software products .ire available lor thePET and TRS-80. II yout local denlei doesn't (any CreativeSoftware products or program inlormation, write directly lo theaddress below. When placing an order please note:Specilv computet & progtarn(s). Add $1.50 shipping lor eachprogram ordered, $2.50 lor joystick interlace. California residentsadd 6".. sales lax. VISA MASTKKCI'AHGH accepted. Include

PET Road Race

. $10.00

ureauve auuware

Another great machinedifferent tracks as you

anguuge program gnbrattle with your opp

/es you a imenl to 1

h<iu e nt iluccnish the uk <■

P.O. BOX 4030, MOUNTAIN VIEW, CA 94040

Includes oil slicks, auloi

natic lap counters, a

id an elap

*c(l Mine i lot k

showing tune to tenths

ol seconds

"""""""

LET CR'liDS GET YOU THROUGH THE TAX SEASON

— Standard and Master Tax Programs designed to prepare even the most complex returns.

— General Ledger and Payroll, working in conjunction with the tax programs to further simplify tax preparation.

— Tax Pacs used by individuals for at-home preparation.

— NEW for this year — Corporation Tax Programs.

CPAids

• Microcomputer software developed by CPA's

• Used Nationally the past two years

• Available on North Star Basic and CP/M

For more details write:

Computer Tax Service • 1640 Franklin Ave. • Kent, Ohio 44240or contact the dealer nearest you:

Alaska

UBIQ

500 L St.

Anchorage, Alaska 99501

California

Coast Computer Center1685 Tustin Ave. #9Cost Mesa, Ca 92627Computerland6840 La Cienga Blvd.Inglewood, Ca. 90302Pro Data Group14522 Acacia Dr.Tustin, Ca. 92680

Delaware

Computer Ease, Inc.403 Milltown Rd.Wilmington, De. 19808

Florida

Computers For You, Inc.3608 W. Broward Blvd.Ft. Lauderdale, Fla. 33312

International Computer

Systems2210 Ponce-de-Leon Blvd.Coral Gables, Fla. 33134

MISA

478 NE 125th St.

N. Miami, Fla. 33161

P & L Computers

2550 Palm Beach Lakes Blvd.

Suite 208

West Palm Beach, Fla. 33409

Indiana

Computer Center of

South Bend19819 Orchard St.South Bend, In. 46637

Iowa

Central Computer1107 Airport Rd.Ames, Iowa 50010

Louisiana

Micro Business Systems3823 GilbertShreveport, La. 71104

Maryland

The Computer Workshop, Inc.1776 Plaza1776 East JeffersonRockville, MD. 20852

Michigan

United Microsystems Corp.2601 South State St.Ann Arbor, Ml. 48104

Minnesota

The Computer Room, Inc.3928 Beau D'Rue Dr.Eagan, Mn. 55122

New Jersey

Computerland of Morristown2 Dehart St.Morristown, NJ 07960

Tax Ease226 Avon Rd.Cherry Hill, NJ 08034

New Mexico

Microsys Inc.7800 Phoenix NEAlbuquerque, NM 87110

New York

The Computer Corner200 Hamilton Ave.White Plains, NY 10601Micro Innovations420 Lexington Ave.NY, NY 10016

North Carolina

Byte Shop of Charlotte6341 Albemarle Rd.Charlotte, NC 28212Coastal Computer Co.P.O. Box 333Jacksonville, NC 28540

Computerland of Charlotte3915 E. Independence Blvd.Charlotte, NC 28205

Ohio

Bethel Computers1700 E. Main St.Kent, Ohio 44240Computer Tax Service1640 Franklin Ave.Kent, Ohio 44240

Texas

Interactive Computers7620 DashwoodHouston, Tx. 77036

Virgina

Command Systems, Inc.727 23rd St. S.Arlington, Va. 22202

Washington

Magnolia Microsystems2812 Thorndyke Ave. WestSeattle. WA 98199

Circle 72 on inquiry card.

BYTE September 1979 223

Circle 330 on inquiry card.

Circle 85 on inquiry card.

RAM CHIPS

4044

TYPE

4Kby1 — 18-pin — 5V, 5% supply

These are the same factory prime chips used in ourpremium quality RAM boards. May be 4044, 4041,5257, 6641, or 9044, depending on manufacturer. Allhave 4044 pinout and timing specs. All guaranteed 30days.

■doooiioimoeoinnioiiiiooo>iioiioo80»oo»iiiiotmooeaoooao8a80oooooo800Ciie88W8»MlHH»»»»8»m

1-31 chips32-6364-99100-499

250 nsec.

$7.506.505.755.50

450 nsec.

$6.505.504.754.50

Circle Inquiry number for free newsletter.

h

Seattle Computer Products, Inc.

1114 Industry Drive, Seattle, WA. 98188(206) 575-1830

TRS-80... all business! !

...with CP/M, CBASIC2,& applications software.

CP/M Operating System (w/Editor, Assembler,

Debugger, Utilities & 6 manual set) $150

CBASIC2 Compiler (w/manual) $ 95

DESP00L Print Spooler (w/manual) $ 75

*Osborne & Assoc. PAYROLL W/C0ST

ACCTNG $250

*Osborne & Assoc. ACCTS. RECEIVABLE &

ACCTS. PAYABLE $250

*0sborne& Assoc. GENERAL LEDGER $250

*=CBASIC2 source programs; add $15 (each) forapplicable O & A book.

APH - Self-administered Automated Patient

History $175

| DOWNLOAD -TR-80 (or other)

CP/M to CP/M $95

data/program (source or object) transfer overRS232 link

Send 30ri SASE for add'l. Software avail, (includingCP/M Users Group software) and FREE "CP/M Primer."

CA residents add 6% tax. Visa, M/C,M/0,Check OK.

(714)848-1922

aOdt NEWMAN AVENUE

HUNTINGTON BEACH. CALIFORNIA 92647

ffainrcinroT^

North Star* andPASCAL Users:

JltUifce's

announces

Hard disk and 8" drive interfaces to NorthStar DOS and BASIC and PASCAL

TIMESHARING

for the Horizon—

Interrupt-driven, bank switchingtimesharing software; supportsNorth Star DOS and BASIC andPASCAL.

A complete selection of business applica-tion software is available for North Star*systems.

Write or call for descriptive literature.

Micro Mike's, Incorporated

905 South Buchanan * Amarillo, Texas 79101 * USA(806) 372-3633

SORCERER*SOFTWARE!

FOUR PROGRAMS ON CASSETTES

FASTGAMMON™ by Bob Christiansen. Thousands of people are already playing FAST-GAMMON on TRS-80 and Apple. Now it is ready for SORCERER, with the sharpest graphicsever! Backgammon players love this machine language program that provides a skillfulopponent. Eight-page instruction manual includes rules of backgammon. $19.95

PLOT by Vic Tolomei. Now Apple owners will be envious of how easy you can get goodgraphics on your SORCERER. PLOT includes both a super high resolution mode and a quicklow resolution mode. Both are accessible from your BASIC programs using simple com-mands. Hi-res & lo-res examples included on tape. 514.95

Z-80 DISASSEMBLER by Vic Tolomei. Decode machine language programs, includingSORCERER'S monitor and ROM-PACs, with this Z-80 Disassembler written in BASIC. In-struction mode prints out machine code and Zilog mnemonics in standard format. Or usethe ASCII mode which converts machine code to ASCII. $14.95

MAGICMAZE™ by Vic Tolomei. A challenging maze game. Ten levels of play. Holding yourlantern, you wander through a maze trying to stay on the right path and avoid pitfalls.Automatic scoring tells you how good a pathfinder you are. $11.95

SOFTWARE INTERNALS MANUAL FOR THE SORCERER by Vic Tolomei. A musl foranyone writing software for the SORCERER. Seven chapters: Intro to MachineLanguage, Devices & Ports, The Monitor, Cassette Interface, BASIC structure,Video & Graphics, The Keyboard. Indexed. Includes diagrams and software rou-tines. 64 pages. 514.95

QUTlLITy SOFTWARE

6660 Reseda Blvd., Suite 103. Reseda, CA. 91335Telephone 24 hours, seven days a week: (213) 344-6599

WHERE TO GET IT: Ask your nearest Sorcerer dealer to see Quality Software's Sorcererprograms. Or, if you prefer, you may order directly from us. MasterCharge and Visa card-holders may telephone their orders and we will deductSI from orders over S19 to compensatefor phone charges. Or mail your order to the address above. California residents add 6% salestax. Orders outside North America add $5 for registered airmail, pay in U.S. currency." The name "SORCERER" has been trademarked by Exidy, Inc.

224 BYTE September 1979

Circle 204 on inquiry card.

Circle 321 on inquiry card.

10-DAY FREE TRIAL

Send for ourFREE Catalog

Keyboard CKeyboard CKeyboard BKeyboard NKeyboard CKeyboard BKeyboard N

4K8K

16K16K32K32K

32K

C — calculator keyboard (only version with tape deck)

B — Large Keyboard (graphics not on keys)

N — large keyboard with graphics symbols

Used 8K PET with 90-day warranty $650

WE BUY USED PET APPLE and TRS-80 COMPUTERS

$100 FREE ACCESSORIES

WITH 16K0r 32KPET

Terminal Package with 8K

PET ACCESSOR

Commodore Dual Floppy Disk DriveNEW! T/C 2001 Terminal Package for

Second Cassette — from Commodore

Commodore PET Service Kit

Beeper • Tells when tape is loaded

Petunia - Play music from PET

$ 595 Video Buffer - Attach another CRT$ 795 Combo - Petunia and Video Buffer

$995 Betsi 4-slot S-100 Motherboard

$ 995 S-100 PET Interface was $289.00 SALE$1195 New Serial Printer Interlace lor PET ..$1195 Integral Data Printer w new interface$1195 pet - Compatible Seleclric in DeskTTY KSR-33 Screen Printer lor PETCa

u

Hazeltine 1400

LIST SALE

$1295.00

the PET $69.00

$95.00

$30.00

$24.95

$29.95

$29.95

$49.95

$119.00

$99.00

$79.95

$878.95

$895.00

$395.00

I lor Availability

Originate Answerback Modem lor PETBi-directional RS-232 Interfac

Q3X3

CBS31

$320.00$280.00

apple II

200 FR€€ RCC€SSOfll€S

The new Apple II with Applesoft BASIC built-in! Elimi-nates the need lor a $200 Firmware Card and includesnew Autostart ROM for easy operation. This combinedwith the FREE accessories from NCE could save you upto S400 on a 48K Apple II system!

16K Apple II Plus — $1195 (take $100 in free accessories)32K Apple II Plus — $1345 (take $150 in free accessories)48K Apple II Plus — $1495 (lake $200 in free accessories)

Apple II Accessories

Centronics Printer Interface

Disk and Controller

Second Disk Drive

Parallel Printer Card

Communications Card

Hi-Speed Serial Card

Firmware CardHobby Proto Card

»22S

Call lor Availability. $595$495$180$225$195$200$24

OF THEMONTH

Call forAvailability

Microverter RF Mod $35

Sanyo M2544 Recorder $55

APPLE II PRINTER PACKAGE $995

For this low, low price, we choose a Centronics ImpactPrinter and match it up with an interlace and cable foryour Apple II. You save hundreds of dollars. Limitedquantities available.

*5Q

#

New 300 baudOriginate AnswerAcoustic Coupler.Looks good, worksgreat and salepriced at

^$189

CATCOUPLER

■ Desktop Selectrle-Based -Terminal $319!

Super bargain while they last: A desktop terminalbased on an IBM Selectric typewriter for only $319including documentation. These terminals wereoriginally designed for use with timesharing sys-tems where top-quality printing was required. TheIBM keyboard and printer are separated by a threefoot cable and each has its own enclosure (great forcustom installations!. Serial RS-232 interface usesPTTC instead of ASCII codes so you will need to write aconversion program (we have ho ASCII interface forthis model). 14.8 cps, 134.5 baud 13" line length, pica.Sold in AS-IS condition, our warranty is limited toreplacement of missing parts (we check all motors).

IN STOCK NOW

EVERY ITEM IN THIS ADVERTISEMENT IS IN STOCKAND READY TO SHIP, EXCEPT WHERE NOTED.

SAVE UP TO 43% Whlle ,he*last

CENTRONICS PRINTERS

Refurbished excellent working condition.10 day return privilege of course.

90-DAY

SPEED WIDTH PRINT WORKING WARRANTYMODEL (Ipm) (col's) MATRIX PRICE PRICE

SUPER SALE PRICETOO LOW TO ADVERTISE

Immediate Delivery — 2-Year Factory WarrantyYou may have seen the Hazeltine advertised at $850. Youmay have seen it sale prices at $749 or even $699 but ournew price is so low that we can t even advertise it. Call usfor a quote Hurry, we have a limited quantity at this priceThe 8048-based Hazeltine 1400 has a 12 screen. 24x80display. TTY-style keyboard, addressable cursor andRS-232 I O from 110 to 9600 baud

Hazeltine 1410 — $835

Adds a 12-key numeric keypad to the 1400 tor financial or

mathematical applications. 2-year warranty.

Hazeltine 1500 —$1069

Full-capability terminal complete with 12" screen. 24 x

80 display, upper lower case, dual intensity.

Hazeltine 1510 —$1195

Additional memory is added to provide buffered data

entry operations with editing capabilities

Hazeltine 1520 — $1499

Buffered like the 1510 but a microprocessor has been

added to offer independent printer control.

CRT TERMINAL PRINTER PACKAGE

Hazeltine 1520 and a Centronics 761-5 together for only$2,295. The perfect work station for use with a bufferedcommunications system. Terminal operations and print-ing may operate simultaneously. • Refurbished

4>

700 13-90 132 5x7

660

1 075

Character Elonqation

701 25-120 132 5x7

695

1 175

Char Elong Bidirectional

761 60 132 7x7

695

1 025

Teleonnter Bidirectional

"Model 761 includes Keyboard

NCE/CompuMart

SELLING COMPUTERS BY MAILSINCE 1971

1250 North Main Street, Department BY99P.O. Box 8610 Ann Arbor, Michigan 48107

(313) 994-3200

' Member:Computer DealersAssociation

, Inc.

SANYO MONITOR

9-inch 15-Inch

-$£40. $169-$400. $279

SANYOMONITOR

when you buy the

SORCERER

$995

Z-80 Processor • Full-size keyboard • User definablecharacters • Up to 32K on-board RAM • InterchangeableROM PACs-30x64 display-Resident 4k monitor ROM-Dual Cassette I/O • Serial and Parallel I/O ■ Completeoperator's manual

Simply add a monitor and tape decks to complete thesystem. Can be used as a terminal Microsoft BASICROM PAC is standard. NEW! Exidy Word ProcessingROM PAC now available which handles tabs, search,replace, etc., many different printers and can be usedwith cassette or disk. The most flexible W, P system we'veever seen.

Sorcerer 8K $995

Sorcerer 16K $1150

Sorcerer 32K $1395

Word Processing ROM PAC Call lor Availability $99

IMPORTANT ORDERING INFORMATION

All orders must include 4% shipping and handling. Michigan residentsmust also add 4% for state sales tax. All foreign orders (except Canada)need an additional 10% for shipping and handling. We cannot processyour order without these.

Phones open from 9:00 a.m. to 7:00 p.m. EST Monday-Friday, 10:00 a.m. to5:00 p.m. Saturdays • P.O.'s accepted from D & B rated companies — ship-ment contingent upon receipt of signed purchase order • All pricessubject to change without notice • Most items in stock for immediateshipment — call for delivery quotation • Sorry, no C.O.D.'s •In the Ann Arbor area? Retail store open 11:00 a.m. to 7:00 p.m. Tuesday-Friday, 10:00 a.m.to 5:00 p.m. Saturdays (Closed Sunday and Monday)

Circle 283 on inquiry card.

BYTE September 1979

YOUR #1 SOURCE FOR

California Computer Systems

Available at HOBBY WORLD

Model 2500AS-lOO

Wire WrapBoard

• 5-100 BUS compatible

• Double sided PC board

• Plated thru holes

• Perimeter ground

• All S-100 BUS signals labeledand numbered

• Accommodates standard sizeIC sockets

• 4 to-220 regulator positionsavailable

• Allows either positive or neg-ative regulators

• Dense hole configuration. Cat No. 1600 $ 27.00

Model 2501AS-lOO

Solder Board

• 5-100 BUS compatible

■ Double sided PC board

■ Plated thru holes

• Perimeter ground

• All $-100 BUS signals labeledand numbered

• Accommodates standard sizeIC sockets

• 4 to-220 regulator positionsavailable

• Allows either positive or neg-ative regulators

• Dense hole configuration.Cat No. 1604 $ 27.00

[Model2501AS-100l

Mother Board

• 12 slot capability

• All 12 S-100 bus connectors in-cluded

• Low inductance inner-connedto reduce signal noise andcrosstalk

• Active termination of all buslines to further reduce signalnoise and line reflections

• Distributed bypassing of allpower lines

• Solder mask both sides ofboard

• Silkscreen of reference desig-nations

• Simple strong hoard mounting

• Criss-cross BUS lines bothsides of board

• All holes plated thru

• Solder plated circuit areaCat No. 1616 Kit $ 90.00

l Cat No. 1615 A&T $105.00 .

Model 2520AS-lOO

Extender/Terminator

• Active and/or dynamic term-ination

• All power lines fused (or pro-tection

• All S-100 lines labeled andnumbered

• Can be used as an extenderand/or terminator

• Solder mask both sides ofboard

Silkscreened reference desig-nations

• Gold plated fingers

.Cat No. 2520 Kit S 37.95 .

Model 7811A

Apple IIArithmeticProcessor

| • Based on AMD AM9511 de-vice1 Fixed point 16 and 32 bit op-eration

I • Floatingpoint 32bit operation

• Binary data formats

• Add, subtract, multiply, anddivide

I • Trigonometric and inverse tri-gonometric functionsI * Square roots, logarithms, ex-ponentiation| * Float to fixed and fixed to floatconversions1 Slack oriented operand stor-age■ Programmed I/O data transfer

• End signal selectable interrupt

• Supports interrupt daisy chain

• Allows DMA daisy chain

• Power down ROM

| • 256 bytes firmware (ROM) orsoftware (RAM) space avail-able

I Cat No. 1635 $375,00

Model 7114AApple II

Prom Module

The 7114A PROM MODULE per-mits the addition or replacementof the Apple II firmware withoutthe physical removal of the AppleII ROMS. This allows soft-ware/firmware replacement,change, and/or patch to be madeon a ROM or BYTE BASIS. Anon-board enable/disable toggleswitch rs also available.

• BYTE oriented program over-lay

" Selectable prom overlay

• Power down of PROMS

• 14K PROM space available

I • Uses +5 volt 2716 type proms

1 Allows use of DMA/interrupt

daisy chains

I Cat No. 1631 A&T $ 72.00

L Cat No. 1630 Kit $ 62.00

Model 2016Bs-ioo

16K StaticMemory

• Fully static operation

• Uses 2114 type static rams

• +8 VDC input at less than 2amps

• Bank select available by bankport and bank byte

• Phantom line capability

' Addressable in 4K blocks in 4Kincrements

• 4K blocks can be located any-where within 64K bank

• May be used as a 4K, 8K, 12Kor 16K memory board

• Led indicators for board/bankactive indication

, • Solder mask on both sides ofboard' Silk screen with part and refer-ence designation1 Available fully assembled andtested, as a kit, or as a bareboard| Cat N0.I6OIA Kit 450ns 5285.00Cat N0.I6OIB Kit 200ns $340.001 Cat No. 1602A A&T 450ns $330.00LC.1I No.16A2B A&T200ns$385.00 ,

Model 7470AApple II

33A Digit BCDA/DConverter

The 7470 allows conversion of aDC voltage to a BCD number forcomputer monitoring and analy-sis. Typical inputs would be DCinputs from temperature or pres-sure transducers." Selectable interrupt on end ofconversion

• 20QUS per conversion

• -4 to +4 VDC full scale

• Plus or minus .05% nanlinear-

ttv

• Plus or minus 1 count quanti-zation

• Correctible offset error

• Temperature coefficient ad-justment

• Calibration adjustment

• Input offset adjustment

• Floating inputs

• Overange and sign indicators

• Input filter

• Power down ROM

■ Supports interrupt daisy chain

• Allows DMA daisy chain

• 256 byte firmware (ROM) orsoftware (RAM) space avail-able

Cat No. 1621 Kit $115.00LCat No. 1622 A&T $135.00.

Model 2200A

Mainframe

S-100 compatibleIndustrial/commercial qualityconstruction

• Flip-top cover

• Excellent cooling capability

• 12 slot capability (uses model2301 A)

• Input 105. 115, or 12S VAC

• Output +8 VDC, 20A + -16VDC 4A

• Active termination of all buslines

Fan and circuit breaker includ-ed

• Rugged construction

• All parts available separatelyCat No. 1612 Kit $330.00

L Cat No. 1614 A&T $375.00 .

Model 7440AApple II

Programmable!Timer Module

■ Flexible external interfacepatch area for custom inter-face applications

• Selectable prescaler on timer3 capable of 4mhz input

• Programmable interrupts

• Readable down counter indic-ates counts to go to time-out

• Selectable gating for frequen-cy or pulse width comparison

• Three asynchronous externalclock and gale/trigger inputsinternally synchronized

• Three maskable outputs topatch area

• Power down ROM

• Supports interrupt daisy chain

• Allows DMA daisy chain

• 256 byte firmware (ROM) orsoftware (RAM) space .able

Cat No. 1617 Kit $135.00

kCal No. 1618 A&T $145.00A

Apple IIModel 7712A

Synchronous

Serial

Interface

• Conforms to RS-232C [config- Iuration A thru E)

• Supports half or full duplex |operation

• DTE type configuration

• Failsafe RS-232C operation

• 14 STD CLK rates 50-19.2KBAUD plus EXT CLK

• BAUD rates dip switch select-able

• All BAUD rates crystal con-trolled

" Programmable interrupts fromtransmitter, receive;, and errordetection logic

• Character SYNC by one or twoSYNC codes

I • Programmable SYNC code re-gister

I * Standard synchronous signal-ing rate per RS-269JANSI X3.1-1976

Peripheral/modem controlfunctions

I • Three bytes of fifo bufferingon both transmit and receivedate7,8, or 9 hit transmission

I * Optional odd, even, or no par-ity bit

I • Parity, overrun, and overflowstatus checks

I " Power down prom

I • 256 bytes firmware (ROM) orsoftware (RAM) space avail-able '

I • Supports interrupt daisy chain

• Allows DMA daisy chainLeaf No. 1627 Kit $ 90.00 1

Apple IIModel 7710A

Asynchronous

Serial

Interface

• Parity, overrun, and framing Ierror check

• Optional divide by 16 clock |mode

• False start bit detection

• Software programmable inter- |rupts

• Data double buffered

• One or two stop bit operation |

• Power down PROM

• 256 bytes firmware (ROM) or Isoftware (RAM) space avail-able

• Supports interrupt daisy chain

• Allows DMA daisy chain

• 134.5 BAUD available for sol |eclric interface

• Conforms to RS-232C (config-uration A thru E)

• Supports half or full duplexoperation

• OCR type interface

• Failsafe RS-232C operation

• 14 STD CLK rates 50-19.2KBAUD plus EXT CLK

• BAUD rates dip switch selec-table

• All BAUD rates crystal con-trolled except EXT

• 8 and 9 bit transmission

• Optional even, odd, and noparity bit

• Programmable control regis-ter

Cat No. 1624 A&T $145.00LCat No. 1623 Kit $ 90.00 A

Model 7720AApple II

ParallelInterface

Two bi-directional 8 bit busesfor interface to peripherals

• Tow programmable controlregisters

• Two programmable data dir-ection registers

• Four individually controlledinterrupt input lines; two use-able as peripheral control out-puts

1 Handshake control logic for

input and output peripheral

operation1 High impedance 3 stale and

direct transistor drive pheri-

pheral lines

• Programmable interrupts

1 CMOS drive capability on side

A peripheral lines> 2 TTL drive capability on all A

and B side buffersI ■ Power down ROM

Supports interrupt daisy chain

• Allows DMA daisy chain

[ • 256 bytes firmware (ROM) orsoftware (RAM) space avail-ableI Cat No. 1633 A&T $105.00I Cat No. 1632 Kit $ 62.00

Model 7500AApple II

Wire WrapBoard

I The 750OA is used for the

I prototyping or building of uniquel

circuits for the Apple II

computer.

• All bus signals labeled on Iboard

• Perimeter ground

• Size: 7 inch long x 2.75 inch Ihigh

■ All holes plated thru

• Gold plated conector fingers ICat No. 1606 $ 19.00 |

Model 751OAApple II

Solder Board

The 7510A is the same as the7500A except it is designed forsoldering of circuits-1 Cat No. 1607 $ 19.00

Model 7590AApple II

Etch Board

1 The 7590A is a (wo sided copper |board which allows the actualetching of circuits for use in the |Apple II computer.

I Cat No. 1608 $ 19.00

Model 7520A

Apple IIExtender

Board

The 7520A is a handy toolwhen debugging or testingmodules in the Apple II.ifal No. 1611 Kit $ 21.00J

19511 BUSINESS CENTER DRIVE

226 BYTE September 1979

Circle 170 on inquiry card.

A

I

COMPUTER ELECTRONICS

CALL TOLL FREE:

(800)-423-5387

CA, HI, AK:(213) 886-9200

SOFTWARESOFTWARE

Star Trek III

The most advanced ver-sion we've seen!TRS-80 L2, 16KCat No. 1041 $14.95

Backgammon

You play against the com-puter! With hints onstrategy, etc. Extremelygood! TRS-80 L2-16KCat No. 1481 $10.95

Sargon Chess

Winner of all tournaments!6 levels of play, excellent

fraphics.RS-80 L2, 16KCat No. 1093 $19.95Apple II, 16KCat No. 1317 $19.93

Tarot

Excellent graphics, frigh-teningly accurate!TRS-80 L1/L2 4KCat No. 1042 $5.95

Air Raid

An arcade-type real time

fame of target practice,xcellent GraphicsTRS-80 L1/L2 4KCat No. 1186 $14.95

Microchess

Graphic Chessboard with3 levels of play.TRS-80 L1/L2, 4KCat No. 1182 $19.95

Apple II

Cat No. 1183 $19.95

CASSETTESCASSETTES

Fortran Plus

By Microsoft! For TRS-80L2 with 32K

single

anddisk.Cat No. 1341 $340

Beat the House

4 Casino games: Black-jack, roulette, craps, slotmachine. Excellent simu-lation.

TRS-80 L2, 16KCat No. 1347 $14.95

Apple II, 16K

Cat No. 1349 $14.95

Level III Basic

Gives your TRS-80 the

fiower of a full size sys-em. Disk commands, ad-vanced editing, etc.TRS-80 L2, 16KCat No. 1332 $49

Bridge Challenger

You and dummy playagainst the computer inregular contract bridge.Either you or comp sets

TRS-80 L2, 16KCat No. 1195 $14.95

Apple 1GK

Cat No. 1196 $14.95

MachineLanguage Monitor |

Allows you to interact dir-ectly with the TRS-80 atmachine language level.11pp manual.TRS-80 L1/L2Cat No. 1048 $23.95

Daily Biorhythm Electric Pencil

Plots a 31 day graph cen-tered on the day youcompute.TRS-80 L1/2Cat No. 1051 $5.95

The famous word proces-sor for the TRS-80 L1/L216K

Cat No. 1338 $95L2 diskette versionCat No. 1338D $145

VERBATIM574 Diskettes I$27 box of lO

4 boxes for $1OO

Cat No. Type Us*

1147 Soft sector TRS-80, Apple

1148 Hard, 10 hole North Star

1149 Hard, 16 hole Micropolis

8" Disks

$37 box of lO

3 boxes for $100

• IBM compatible

• Single density

• Individually certified

I Cat No. 1145 Type 32-1000Description32 sector holes, 1-index hole

ICat No. 1146 Type 34-1000I interchangeable with IBM32,|I 3740, 3770, 3790, etc.

EDGE

CONNECTORS

• Cold plated

Description

S-100, Imsai type, Solder-tailCat No. 1376 Price $4.00 |

S-100, Imsai type, wire-wrapCat No. 1428 Price $4.25

S-100, Altair-type, solder-tailCat No.1388 Price $4.00

86-pin Motorola type,

wirewrap

Cat No.1389 Price $2.50 ,

from Novation

CAT Acoustic

Modem

• For TRS-80, Apple, etc.

Lets your computer talkto other computers overstandard telephone lines.Also communicates withany Bell 103 compatible

$195

modem. Designed specifi-cally (or small computers!Fully assembled and tes-

ted.

Cat No. 1480

Anadex Alphanumeric Printer

$925 • For TRS-80, Apple, etc.

Features 80 columns, 84lines per minute, superhigh reliability, 9x7character font. Completelyself contained, perfect forterminals or as a standalone printer. Prints com-plete 96 character ASCIIfont. Complete with inter-face for RS232C and20/60mA current loopmode. Also Centronicsplug compatible interfacewhich accepts data in aparallel bit, serial char-

acter synchronous form.Programmable baud rate,plus dozens of other fea-tures found only in prin-ters costing twice asmuch.

Cat No. 1342 DP8000 Printer $925

Cat No. 1343 TRS-80 Adapter Cable $40

Cat No. 1456 3000 sheets 1 part paper $31.50

Cat No. 1457 1500 sets 2-part paper $40.50

Cat No. 1458 1000 sets 3-part paper $40.50

RECTIFIERS & BRIDGES

Order by Cat No, Voltage, and Current

1A

3A

12A

35A

2A

6A 25A

RECT.

RECT.

RECT.

RECT.

BRIDGE BRIDGE BRIDGE

#1001

#1002

#1391

#1392

#1003

#1004 #1034

50V .05

.12

.36

.80

.30

.50 1.20

1O0V .06

.16

.50

.98

.45

.65 1.50

200V .08

.20

.64

1.15

.60

.80 2.00

400V .10

.24

.78

1.35

-

2.50

600V .12

.30

.98

1.60

800V .14

1.26

1.95

-

.10O0V .16

1.54

2.30

SSM

Available atHOBBY WORLD

|Cat No.1408140914101400 A

1401A

14021405140614071425142614201422

14241440

14331434

Model

Price

SB1 kit

$150

SB1 a&t

$212

SB1 bb

$35

MB6B kit

450 ns

$139

MB6B a&t

$139

450 ns

$183

MB6B bb

$26

MB7 kit

$325

MB7 a&t

$370

MB7 bb

$26

MB3 kit

$54

M83 a&t

$108

MB4 kit(2MHz)$80

MB4 a&t

(2MHz)

$132

MB4 bb

$26

PB1 kit

w/textool

$125

MB8A kit

$78

MB8A a&t

$125

Cat No.14351436143714291430143114271428

140314171418141914381439141414151416141114121413

ModelMB8A bbMB9 kitMB9 a&tOB1 kitOBI a&tOB1 bbXB1

Connector forXB1

CB-1 kitVB1B kitVB1B a&tVB1B bbVB2 kitVB2 a&t■02 kitI02 a&tI02 bbI04 kitI04 a&tI04 bb

Price$26$64

$118$45$74$26$10

$4

$119

$129

$175

$26

$135

$195

$48

$75

$26

$139

$185

$26

Ribbon Cable

CLEARANCE

SALE

{•Flat style, 28AWC| 'Order by Cat No. 7767& conductors

Cond. 10 ft.

10 $1.00

26 2.60

34 3.40

40 4.00

IC Sockets '

Penny-A-Pin

Texas Instruments

Solder tail

Package quantities only

Order by Cat

No. 1117 and

pins

8 pin

20 for $1.60

14 pin

10 for $1.40

16 pin

10 for $1.60

18 pin

8 for $1.44

20 pin

8 for $1.60

22 pin

8 for $1.76

24 pin

3 for .72

28 pin

3 for .84

40 pin

2 for ,80j

/Hatchless Systems - TRS-80

/Minidisk Drive

Accesses twice as fast asthe Radio Shack drive,plus offers 40 tracks asopposed to 35! Includes| case, power supply, and

cables. Completely assem-bled and tested, ready toplug in and go! Simple

$395

modification tosecond drive!Cat No. 1375 MINIDISK

DRIVE $395Cat No. 1396 4 DRIVE

EXPANSION CABLE $40Cat No. 1147 Verbatim Diskettesfor above - box of 10 for $27

Send for

FREE

CATALOG

Featuring:

The best selection of com-

fmtcr accessories add-ons,actory fresh IC's, led's,semi's, software, PC aids,

? prototyping aids, books,est equipment, and more!Always updated! Dozensof new products every JJssue!

rPay by check, COD, Visa,'or Mastercharge. Orderby phone or mail. Mini-mum order $10. Pleaseinclude phone number andmagazine/issue you areordering from. USA: Add$2 for shipping/handling

P round; $3 for air.OREIGN: Add. $3 forsurface. $6 for air. COD's$1 add'tl. Guaranteed sat-isfaction for 120 days oryour money back! Not re-sponsible for typographicalerrors. We reserve thel right to limit quantities.

Dept. B9 NORTHRIDGE, CA. 91324

Circle 170 on inquiry card.

BYTE September 1979 227

POB

[AMIIHCAN 1■ XPRCBS 1

Electrolabs

6721, Stanford, Co. 94305

,„ cw/om/0 415-321-5601//»'„- 800-227-8266TLX: 345567

FLOPPY SYSTEMS

NEW .

CATALOGUE

Crystals

Integrated circuits

Keyboards

Lasers

LSI-11

Media

RAMs

S-100 Components

Z-80 Components

8" Siemens FDD 120-8 Drive

All. Siemen's options includedin this drive which can be con-figured hard or soft and singleor double density. (Others giveonly stripped unit) $399.00

"Power One" Model CP206Floppy Power Unit For two

drives going full-out, and poss-ip ably more on less severe service.Wf§ 2.8A@>24V, 2.5A@5V, 0.5A@-5V.t J Beautiful quality. $99.00

DISKETTES (Standard)

<^

8"

SV"

Boxed 10Boxed 10

539.00534.95

*^~.

Tarbell ("It Works") Interface(Includes cable set for 2 drives)$265.00 BUT ONLY $219.00with purchase of two drives.

Cable Kits 10' with 50 cond.cable and connectors and alsoMolex connectors and powercable: For one drive: $27.50For two drives: $33.95, andfor three drives: $38.95

CABINETS for FOD120 and801R Drives, or CP206 powersupply. Matte finish in marresistant black epoxy paint.

ng type design. $29.99

ELECTRO LABS is proud to announce appointment asDISTRIBUTOR by CI I-Honeywell Bull.

PRICE BREAKTHROUGH on SUPERDJSK 10MBY! $3495.00

General purpose controller (requires 2 parallel I/O ports) 1500.00

S-100 Controller (DMA) 995.00

"RL-01/RK-05" surrogate 1900.00

(transparent to RT, RS, RX)

SOFTWARE: (CP/M Compatible)

SUPERD0S1

(Z-80) $695.00 ^

MICR0D0S1

(TRS-80)... $199.00Power supply (switching) jL

$395.00

Enclosure (desktop) "~"1,".

£ 99 00 * aa,uu Removeable Media Cartridge Drive

Hi

Used Sylvania 12" Video Moni-tors. Composite video 15mhz,115vac, 50/60hz New Tube. Asshown $109 OEM style withoutcase: $99, Anti-glare tube optionadd $12. Specify p4 or p39

ESAT 200B

BI-LINGUAL 80x24COMMUNICATINGTERMINALScrolling, full cursor, bell,8x8 metrix, 110-19,200baud. Dual Font Appli-cations. Arabic & Hebrew,Multilingual Data Entry,

5%"

MINI-FLOPPYDRIVE$299.00

- single or double dens-ity - quick access time

- high reliability &durability

Mini-floppy CABLE KIT:for TRS-80 or yourTarbell controller.$24.95

Daisy Wheel PrintersQume Sprint: 3\45

Print wheels $8.95 Ribbons $5.95

OEM Style mechanism $1399.00

Forms Drawing, Music Instruction, Specialized Graphics (e.g. Games, Chemical Plants,Switchyards) $349.00 We carry keyboards, cases, power supplies, etc., enough to makean entire system.

228 BYTE September 1979

Circle 115 on inquiry card.

The

TO ORDER CALL TOLL FREE 800-223-7318

• 16-bit microprocessor

• 16K RAM

• 13" color monitor(24 lines of 32 chrs.)

• 26K BOM opereting system(Includes 14K BASIC)

• Sound - 3 tones. 5 octaves

• 16 colors: 192 x 256 res.

• Large Tl library of ROMprograms available.

Includes 13"lolor Monitor!!

onlyFINALLY k—— 1$1150

TEXAS \H»^INSTRUMENTSTI-99/4Home Computer

Many Peripherals. Coming soon!

APPLE II PLUS ONLY$1195

A complete sell-contained computer system with APPLESOFT floating pointBASIC in ROM. lull ASC 11 keyboard in a light weight molded carrying case.

Features Include:

• auto-start ROM • Hi-Res graphics and 15 color video output.

• Expandable to 48K.

Disk $595 Programmer's Aid 50

Add-on Disk 495 Speechlab 229

Pascal Card 495 Lightpen 250

Business Software 625 Communication Card 225

Monitor 149 Modem 200

PnnterCard 180 EPROM Programmer 100

NEW D. C. Hayes MICROMODEM II

• Combines the capabilities of a communications card and acoustic coupler.

• Plugs directly into Apple slot and modular telephone Jack. *o^n

• Auto dial/receiver*FCC approved Only* $379

NEW Mountain Hardware SUPERTALKER

• Digitized speech recording and playback. • Must be heard to be believed!

• Foreign language teaching pack available. • Software compatible.

only $279

SUPRBRAIN

TM

INTE3TEC

DATA

SYSTEMS

ONLY

$2995

d:::m

on

iv $795

• 14K ROM Operating system

• 8K RAM Memory

• 9" Video Monitor

• Built in Keyboard

• Digitally controlled tape

S1495 Complete!16K Model add $20032K Model add $500

PET

More than an intelligent terminal, the SuperBrain outperforms many othersystems costing three to five times as much. Endowed with a helty amount ofavailable software (BASIC, FORTRAN, COBOL), the SuperBrain is ready totake on your toughest assignment. You name it! General Ledger, AccountsReceivable, Payroll, Inventory or Word Processing. . .the SuperBrain handlesall of them with ease.

Features Include:

• two dual-density minifloppies with 320K bytes of disk storage

• 64K of RAM to handle even the most sophisticated programs

• a CP/M Disk Operating System with a high-powered text editor,assembler and debugger.

FREE

$35 of Software with purchaseof any computer on this page.

COMPUCOLOR II Disk-Based Model 3Advanced hardware and software technologygives you

• 13' Color Display

• Advanced Color Graphics

• 51K Disk Built-in

• 16K ROM Operating System

• 8K RAM User Memory

• 4K RAM Refresh

• 8080A Microcomputer

• RS-232 I/O

|^tSPECIAL SPECIAL

$200 FREE Software with,Jy|purchase of 8K PET >* |

Over 1000 softwaretapes, books, diskson display.Come in and brouse.

JM Xacc

V Wf Data General

BUSINESS

COMPUTER

IMSAI

The low cbsl solution

lor all small business

problems A wide varn

of software is

available lor ail your needs

PCS series include dual llopp.es. 32K RAM.

I O. DOS. BASIC

• PCS-42 (400KB) $3295

• PCS-44 (780KB) $3995

VDP-42 series adds video terminal, key-board and VIO to above

• VDP-42 $4995 • VDP-44 $5595

• VOP 80 $7995 • VDP 180 $8995

10 MegabyteSystem $17,040

DATA GENERAL^ micro NOVA

0 The ultimate in smallBusiness Computerswhen matched withCOMPUTER FACTORY'Sinicomputer. Software:Accounts Receivable/Payable,Inventory Control/ Order Entry.Genreal Ledger, Payroll Systems.. . .from $12,140 for 64K computerwith cabinet, printer terminal, video terminal.dual disk and mutll-user operating system!

SOUNDWARE

MUSIC BOX

only $29.95

Music and Sound Effects for PET, TRS-80.& Compucolor ll Add music and sound effects toyour programs. Compose, play, and hear musicon your computer. Completely self-contained.Free programs.

This fantastic program disk allows the statistician,Moving mathematician, trader in stocks, money or

Average commodities, the ability to maintain 30 databasePlot series of up to 300 values and plot 3 different moving

Program averages of a series at the same time, in 3 differentFOR colors. Files can be updated, deleted, changed,

APPLE extended, etc.

A sure value disk at only $40!

Word Processing For Apple on disk...$50

■ £4 User Defined Cher

• 240 » SI? Resolution Grai

Module! dtugn al

lor program* end RDM PAC

luture language i

COBOL. PILOT. FORTRAN.

8KS 99516K$114532K $129548K $1445

SORCERER

SPECIAL12 Video Monitor> for SORCERER($299 value)

ONLY

125 with 8K unit95 with 16K unit65 with 32K unit

ANDERSONJAC0BS0N

S41 1/0 TerminalIdeal (or word procei

mg end imall bun

• ASC 11 Code

• 15 cot Printout

• High Quality Selective Printing

• Use Keyboard tot PET

• Retiebte heavy duty Mechanum

• Completely Refurbished by A.J.

• Service in 15 Major CitiM

foCKII

NOW IN s

Parallel

$1095

$1195

RADIO SHACK • PET • SORCERER|APPLE • COMPUCOLOR • ETC.

PRINTERS • PRINTERS • PRINTERS

The COMPUTER FACTORY'S extensive CENTRONICS 779 $ 945

inventory and wide seler.lion of computer TRENDCOM 100 375

printers assures you of finding the printer TRENDCOM 200 N/A

best suited for your needs and INTEGRAL DATA 795

specifications The following printers work DIABLO/XEROX 2695

well with all known personal computers COMPRINT 560

Min Credit CardOrder $75

VISA*

OpenMon.-Fri.10-6

NY restdnnis add 8°'6 sales lax • Same day Cat 1fl Ashipment on prepaid and credit card orders ***"■ I"-**• Add S5 shipping lot computers. $3 forboards. $1 each cassette fape.

NEWCENTRONICS 730

50 CPS ■ MICROPROCESSORCONTROLLED!

Tractor & Friction Feed • UsesSingle Sheets, Roll, Fanfold • Upper& Lower Case • Light Weight

Parallel $995Serial $1045

«&>*£&

TO ORDER CALL TOLL FREE 800-223-7318

vH»

o^

iW

TLft fVMUIDI ITCD CAPTHDV 485 Lexinqton Avenue 750 Third Avenue Mew York. N.Y. 10017I lit? V-fWlVIn U I Cn TMV^ I \JT\ I (212) 687-5001 (212) PET-2OOI Foreign order desk ■ Telex 640U55

BYTE September 1979 229

computerproducts, inc.

11542-1 KNOTT STREET

GARDEN GROVE, CALIFORNIA 92641

(714) 891-2663

MICROBYTE Z80/I-O

• A complete single board Z60ACPU and serlal/paralle I/O system

• Fully S-100 Bus compatible,IMSAI, ALTAIR

• Z80A CPU (4 MHz version of the280)

• 158 Instructions — superset ofand upward compatible from the8080's 78 Instructions

• Provision for up to 4K on boardmonitor program using 1K (2708),2K {2716), 4K 2732

• On board EPROM can be hard-ware and/or software deselected

• 2 MHz or 4 MHz operation isswitch selectable

• 0 or 1 wait state for all cycles isswitch selectable

• 2 RS-232C serial ports with 8251USARTs

• Serial baud rates switchselectable

• 24 programmable parallel I/Olines (uses 8255)

Gold Contacts for higher relia-bility

Power requirements: + 8V ®800mA, + 16V, @ B6mA, - 16V@ 100mA

X" rating temperature 0*-55"Coperate with or withoutIMSAI/ALTAIR front panel' Low power shottky tri-state buf-fers on all address and data lines1 Fully warranted for 120 days fromdate of shipment

$325.(

IMSAI CONN.

100 PIN-SOLDERTAILGOLD CONTACTS

$3.00 each or 10/2.60 each

8251

PROGRAMMABLE/U-ARTTESTED® 4 MHZ

$5.00 each

TRS-80

Floppy disk drive withcabinet & pwr. supplycompatible with RadioShack Interface. Ass-embled & tested with1 yr. warranty onparts & labor.

Mfg. by Lobo Drive

$385

Interface Cable Available

SPECIAL

.1 @ 12 VOLTSCERAMIC CAP

10$eachor

100/$9.00

MICROBYTE 16K STATIC RAM BOARD

Fully S100 Bus Compatible,

IMSAI, SOL, ALTAIR, ALPHA

MICRO

Uses National's Low Power 5257

4K x 1 Static Rams

2 MHz or 4 MHz operation

On board single 5 amp regulator

Thermally designed heat sink

(board operating temperature 0a

- 70*C)

Inputs fully low power Shottky

Schmitt Trigger buffered on all

address and data lines

1 Phantom Is jumper selectable topin 67

Each 4K bank addressable to any4K slot with in a 64K boundary.4K hardware or software select-able

< Selectable port address4K banks can be selected or dis-abled on power on clear or reset

Will operate with or without frontpanel

Compatible with ALPHA MICRO,with extended memory manage-ment for selection beyond 64KNo DMA restrictionLow power consumption 1.3 ampFully warranted for 120 days fromdate of shipmentExtended addressing up to 1megabyte of addressable ram

450 NS $320.°°300 NS $340.00

MICROBYTE 32K STATIC RAM BOARD

• Fully S1O0 Bus Compatible,IMSAI, SOL, ALTAIR, ALPHAMICRO

• Uses National's Low Power 52574K x 1 Static Rams

• 2 MHz or 4 MHz operation

• On board single 5 amp regulator

• Thermally designed heat sink(board operating temperature 0*- 70"C)

• Inputs fully low power ShottkySchmitt Trigger buffered on alladdress and data lines

• Phantom Is Jumper selectable topin 67

• Each 4K bank addressable to any4K slot with In a 64K boundary.

• 4K hardware or software select-able

• One on board 8-bit output portenables or disables the 32K In 4Kblocks

• Selectable port address

• 4K banks can be selected or dis-abled on power on clear or reset

• Will operate with or without frontpanel

• Compatible with ALPHA MICRO,with extended memory manage-ment tor selection beyond 64K

• No DMA restriction

> Low power consumption 2.3 —2.5 amps

• Fully warranted for 120 days fromdate of shipment.

Extended addressing up to 1megabyte ol addressable ram

450NS$620.00300NSS650.00

MICROBYTE MOTHERBOARD

• Extra wide ground plane

• Silk screen and solder mask

• Assembled and tested

> Active Diode termination

> Slot for IMSAI front panel• Terminal block connection for

easy hook-up

9 slot kit $70.00A&T$100.0020 slot kit$125.00A&T$155.00Bare Board 9slot$30.00 20 slot $50.°°

MICROBYTE DISK CONTROLLER

• IBM 3740 Soft Sectored'Compat-ible

• Z80 or 8080 compatible on S-100Bus

• Single density runs both mini and

full size drives, runs CPM, onShugart, Perscl, Memorex etc.

• Selectable port/address

• On board 2708/2716 for bootstrapor monitor program

• No hardware jumpers, uses plugin modules for different drives

• Uses 1771 B-Qt controller chip

• Assembled and tested

• Specify disk drive used whenordering by mail

$225.°

SHUGART

801-Disk Drive

WITH CABINET & POWER SUPPLY

ASSEMBLED & TESTED

1 YR PARTS & LABOR

Mfg, by Lobo Drive

$585.00

Dual Cabinet & Drives Available

2708's

LOW POWER450 NS.

$8.75 each8for$66.00

SHUGART

SA400

DISK DRIVE INCLUDES CABINET. NO PWR

SUPPLY, CUTOUTS FOR SWITCH, FUSE, &

INTERFACE CABLE

Mlg. by Lobo Drive00

2716

5 VOLT ONLY

LOW POWER

450 ns

$325.

$40.

00

SCANBE/RN

SOCKETS-LO PROFILE

(tin)1-24 25-99 100-499 500 up

REGULATORS

14 PIN

.16

.15

.14

.12

16 PIN

.17

.16

.15

.14

18 PIN

.20

.19

.18

.16

20 PIN

.29

.28

.26

.25

24 PIN

.34

.32

.30

.28

40 PIN

.60

.58

.56

.52

1-9 10-49 50UD

320 T- 5320T-12340 T5340 T-1278H05

1.251.00

.75

.75

6.00

1.15.90.7070

5.70

1.05.85.6565

5.40

NEW PRODUCTS

8086 — CPU BOARD

8088 — CPU BOARD

Double Density Controller

CALL OR WRITEFOR DEALER INFO

CABLEASSEMBLY

for 8" disk drives

(2) 50 PIN CARD -

EDGE CONNECTORS

ON 4ft. RIBBON

CABLE

$20.00ea.

extra conn. $7.00ea.

ORDERING INFORMATION:

Name, Address, Phone

Ship by: UPS or P.P.

Shipping Charge: Add $2.50 up to5 lbs., all excess shippingcharges will be refunded. Credit

cards will be charged appropriatefreight.

TERMS:

We accept cash, check, moneyorders, Visa, and Master Chargecards. (U.S. Funds Only).COD's: on approval onlyOpen Acct's: companies may

inquire for net terms.Tax: add 6% for Calif, residents only

230 BYTE September 1979

Circle 11 on inquiry card.

Circle 230 on inquiry card.

wmam California computer systems

16K RAM BOARD. Fully buffered addressable in 4Kblocks. IEEE standard for bank addressing 2114's

PCBD $26.95

Kil 450NSEC $259.95

PT-1 PROTO BOARD. Over 2,600 holes 4" regu-lators. All S-100 buss functions labeled, gold fingers.PCBD $25 95

PT-2 PROTO BOARD. Similar to PT-1 except set-up to handle solder tail sockets.PCBD $25.95

sSffl

FORMERLY CYBERCOM/SOUD STATE MUSIC.

PB-1 2708&2716 Programming Board with provisionsfor 4K or 8K EPROM. No external supplies require

textool sockets. Kit $124.95

CB-1 8080 Processor Board. 2K of PROM 256 BYTERAM power on/rest Vector Jump Parallel port with

status Kil $119.00 PCBD $30.95

MB-6B Basic 8KX8 ram uses 2102 type rams, S-100

buss. Kit 450 NSEC ...$139.95 PCBD $26.95

MB-7 16KX8, Static RAM uses U.P410 Protection,

fully buffered Kit $299.95

MB-8A 2708 EROM Board, S-100, 8K8X or 16Kx8

kit without PROMS $75.00 PCBD $28.95

MB-9 4KX8 RAM/PROM Board uses 2112 RAMS or82S129 PROM kit without RAMS or PROMS $72.00IO-2 S-100 8 bit parallel /IO port, % of boards is for

kludging. Kit $46.00 PCBD $26.95

IO-4 Two serial I/O ports with full handshaking20/60 ma current loop: Two parallel I/O ports.

Kit $130.00 PCBD $26.95

VB-1B 64 x 16 video board, upper lower case Greek,composite and parallel video with software, S-100.

Kit $125.00 PCBD $26.95

Altair Compatible Mother Board, 11 x 11 Vi x Vt".

Board only $39.95. With 15 connectors $94.95

Extended Board full size. Board only $ 9.49

With connector $13.45

SP-1 Synthesizer Board S-100

PCBD $42.95 KIT $135.95

W7nC//ne WAMECO INC.

FDC-1 FLOPPY CONTROLLER BOARD will driveshugart, pertek, remic 5" & 8" drives up to 8 drives,on board PROM with power boot up, will operatewith CPM (not included).PCBD $42.95

FPB-1 Front Panel, IMSAI size, hex displays. Byte,or instruction single step.

PCBD .-. $47.50

MEM-1 8KX8 fully buffered, S-100, uses 2102 type

rams. PCBD $25.95

QM-12 MOTHER BOARD, 13 slot, terminated, S-100

board only $34.95

CPU-1 8080A Processor board S-100 with 8 level

vector interrupt PCBD $26.95

RTC-1 Realtime clock board. Two independent in-terrupts. Software programmable. PCBD $23.95

EPM-1 1702A 4K Eprom card PCBD $25.95

EPM-2 2708/2716 16K/32K

EPROM CARD PCBD $25.95

QM-9 MOTHER BOARD, Short Version of QM-12.

9 Slots PCBD $30.95

MEM-2 16K x 8 Fully Buffered

2114 Board PCBD $26.95

80B0A $9.95

8212 2.49

8214 4.49

8224 3.49

2708 9.49

5101-1P 6.90

5101-8P $ 8.40

2114 (450 NS) lowpwr... 7.252114 (250 NS) lowpwr... 7.99

2102A-2L 1.50

2102A-4L 1.20

4116 8/89.95

M

(415) 592-1800P. O. Box 424 • San Carlos, California 94070

Please send for IC, Xistorand Computer parts list

SEPT SPECIAL SALEON PREPAID ORDERS

(charge cards not included on this offer)

8KX8 RAM Fully buffered 450 NSEC.2.5 amp typical assembled parts maybe unmarked or house numbered. $99.99

MIKOS PARTS ASSORTMENTWITH WAMECO AND CYBERCOM PCBDS

MEM-2 with MIKOS ~7 16K ram

with L2114 450 NSEC $249.95

MEM-2 with MIKOS =13 16K ram

with L2114 250 NSEC $279.95

MEM-1 with MIKOS #1 450 NSEC 8K

RAM $119.95

CPU-1 with MIKOS #2 8080A CPU $94.95

MEM-1 with MIKOS #3 250 NSEC 8K

RAM $144.95

QM-12 with MIKOS #4 13 slot mother

board $89.95

RTC-1 with MIKOS #5 real time clock $54.95

EMP-1 with MIKOS #10 4K 1702 less

EPROMS $49.95

EPM-2 with MIKOS #11 16-32K EPROMS

less EPROMS $59.95

QM-9 with MIKOS #12 9 slot mother

board $79.95

FPB-1 with MIKOS =14 all parts

for front panel $134.95

MIKOS PARTS ASSORTMENTS ARE ALL FACTORY PRIMEPARTS. KITS INCLUDE ALL PARTS LISTED AS REQUIREDFOR THE COMPLETE KIT LESS PARTS LISTED. ALL SOCKETSINCLUDED.

VISA or MASTERCHARGE. Send account number, interbanknumber, expiration date and sign your order. Approx. postagewill be added. Check or money order will be sent post paid inU.S. If you are not a regular customer, please use charge,cashier's check or postal money order. Otherwise there willbe a two-week delay for checks to clear. Calif, residents add6% tax. Money back 30 day guarantee. We cannot accept re-turned IC's thai have been soldered to. Prices subject tochange without notice. $10 minimum order. $1.50 service charg*on orders less than $10.00.

W034007 ■4000 -

C/MOS (DIODE CLAMPED)

4033 - 22 4069 - .45

4024 -

4026 -

4017 -

4028 -

4079 -

4030 -

4036 -

4D72 -

451 a -

4520 -

4042

4063 -40GS -4066 -

74C02 -74C08-74C1Q-74C20-74C42-74C73-

70 74C90-

74C15I -74C157 -74C160 -74C16S -74C173 -74CI74 -74CI75-74CI03-74C901 -74C90! -74C914 -

3623 STATIC SHIP

IS-3409 Wl BO BITS □YN.5I'

1.9S B3E23 -17 95 BJSIZ9

US AY61013 VAHT -

35« TR1 «HB -

M B703CTELEDYNEB

3*5 n l«B3 fl PSAT -

1.95 90S0A -

2 *5 BZ,b _

-CRYSTALS $3.45 •«

2.000 MHz 6.144 MHz4.000 MHt. 8.000 MHz3.57 MHz 10.000 MHz5.000 MHz 20.000 MHz6.000 MHz

RIBBON CABLEPLAT (COLOR CODED)#30 WIRE26 cond. -.S0/per foot40 cond. ■ ,75/pcr foot50 cond. • .90/oor foot

CTS 206-8 eight position dip switch $1.60

CTS 206-4 four position dip switch $1.45

LIGHT ACTIVATED SCR's to 18. 200 ,V 1A. .$.70

SILICON SOLAR CELLS4" diameter .4V at 1 AMP $10.00

FND 359 C.C..4" $.60 LED READOUTSFCS8024 4 digit DL-704 C.A. .3" $ .75

C.C 8" display 55.95 DL 747 C.A. 6" $150FND503C.C. .5" S .85 HP3400 .8"CC $1.95FND 510 C.A. .5"$ .85 HP3405 ,8"CA $1.95DL 704 .3" C.C. S 85

PRINTED CIRCUIT BOARD

7WATTLD 65 LASER DIODE IR Sa95

2N 3820 P FET S 45

2N 5457 N FET $ 45

2N2646.UJT S .45

ER 900 TRIGGER DIODES 4 SI 00

?N G028 PROG UJT 5 65

MINIATURE MULTI-TURN TRIM POTS100, 1K, 2K, 5K, 10K. 20K, 50K,200K, 1Mcrj, 2Mcg, 5.75 each 3/S2.00

25 watt Infra Red Pulse I SG 2006 Bquiv. )Laser Diode (Spec sheet included) S24.95

VERIPAX PC BOARD $ 12.95

Our new Prototyping is a hi density 4M" x 6V1"single sided 1/16" epoxy board. It will hold 40,24, 16 (34 units). 14 + 8 pin IC's. There arethree busses, + 5V, ground and a Moating buss.There is a pad for a TO-220 regulator. There is a22 pin edge connector with . 1 56" spacing.

FP 100 PHOTO TRANS S .50

RED, YELLOW, GREEN

LARGE LED's. 2" 6/$l .00

TIL-118 0PTO-ISOLATOR $.75

MCT-6 OPTO ISOLATOR S .80

1 WATT ZENERS: 3,3, 4.7, 5.1, 5.6, 9.1,

10, 12, 15, 18, or 22V 6/41.00

MCM 6571A 7x9 character gen . . S 10.75 ,

UNIVERSAL 4Kx8 MEMORY BOARD KIT$69.95

32-2102-1 fully buffered, 1G address linos, onboard decoding for any 4 of 64 pages, standard44 pin buss, may be used with F-8 & KIM

Silicon Power Rectifiers

10.50 16.50

1 7 50 20.00

SAD 1024 a REDJCON 1024 sioge a

IN 4148 <IN91<.1 uf 25V ceran

RS232 DB 26P mala $2 95

CONNECTORS DB 255 female. . S3.50

HOODS .' $1.50

REGULATORS

323K - 5V 3A .

309K

723 .320T-

5, 12, or 15 V

TRANSISTOR SPECIALS

2N6233-NPN SWITCHING POWER $ 1.95MRF-B004 a CB RF Transistor NPN $ -75

2N3772 NPN 5i TO 3 . . . $ 1.00

2N1546 PNP GE TO-3 $ .75

2N4908 PNP Si T0 3 S I 00

2N5086 PNP Si TO 92 . . 4 S 1.00

2N3137 NPN Si RF $ .55

2N3919 NPN S. TO-3 RF S 1.50

2N1420NPNSiTO5 3/$ 1.00

2N3 767 NPN Si TO 66 . . . S .70

2N2222 NPN Si TO 18 . 5 S 1.00

2N3055 NPN Si TO-3 S 60

2N3904 NPN Si TO-92 6/S 1.00

"2N3906 PNP Si TO 92 . 6/4 1.00

2N5296 NPN Si TO 220 . S 50

2N6109 PNP Si TO-220 ... S 55

2N3fi38 PNP Si TO 5 55 1.00

MPSA 13 NPN Si 4/$ 1.00

TTLtC SERIES

M42

4150 -

J--.J"<

Si

»*5 .97 7*161 - 91 743GB - 93

'»*! - S' 74153 - 3! 74393 - 1.B7

744G - 107 76327 - 2.26 74339 - 2 25

DATA CA5SETTES 1/2 HR $.95 *"14 pin headers 3/41.00

MM5387AA . . . CLOCK CHIPS ■ ■ ■ . $5,95

M7001 47.50

MM5369 $3.75

no. 30 wire wrap wire single^^rant^^^ioo/sujq^^^^^

alco miniature toggle switchesmta 106 spot s .95

MTA 206 DPDT 5 1.70

MTA 206 P-DPDT CENTER OFF * -\ 85

MSD 206 P-DPDT CENTER OFF

LEVER SWITCH $ 1.85

6A

1.32

1.92

4.40

DIP SOCKETS

fl PIN .17 24 PIN ,35

14 PIN .20 28 PIN 40

16 PIN ,22 40 PIN .6018 PIN .25

SANKEN AUDIO POWER AMPS

Si 1010 G 10 WATTS $ 7.80

Si 1020 G 20 WATTS $15.70

Si 1050 G 50 WATTS $28.50

TANTULUM CAPACITORS

.22UF 35V 5/41.00.47UF 35V5/$1.00.68UF 35V5/$1.001UF 35V 5/41.002.2UF20V5/4t.003.3UF 20V 4/41.004.7UF 15V 5/41.00

6.8UF 36V 4/41.00

10UF 10V $.25

22UF 25V $ .40

15UF 35V 3/S1.00

30UF 6V 5/41.00

150UF 15V $ .95

68 UF 15V S .50

7Us SERIES

LINEAR CIRCUITS

LM 201 -.75IM30W74B 35LM307 - .30LM 308 - 75LM311 - 75LM3I8 -1.20

LM 324 -.95

LM 380LM 363LM386LM 387

Circle 340 on inquiry card.

BYTE September 1979 231

7400 TTL

SNMOONSN7401NSN7402NSN7403NSN7404NSN7405NSN7406NSN7407NSM74D6MSN7409NSN7410NSN7411NSN7412NSN7413NSN7414NSN7416NSN7417NSN742QNSN7421NSN7422NSN7423NSN7425NSN7428NSN7427NSN7429NSN7430NSN7432NSN7437NSN7438NSN7439NSN744QNSN7441NSN7442NSN7443NSN7444NSN7445NSN7446NSN7447NSN7448NSN745QNSN7451NSN7453NSN7454NSN7459ASN7460N

CD4000CD4001CD4002C04006C04007CD40O9C04010CD4011CD4012CD4013C04Q14CD4015C04016CD4D17CO4018C04019CD402OCD4021CD4022CD4Q23C04024CO4025CD4D26CD4027

74CO074C02

74C0474C0874 CIO74C1474C2074C3074C4274C4B74C7374C74

6.50

7BMG 1.75

LM106H .99

LM300H .60

LH301CN/H .35

LM302H .75

LM304H 1.00

LM305H .60

LM307CN/H .35

LM308CN/H 100

LM309H 1.10

LM309K 1.25

LM310CN 1.15

LM311N/M .90LM312HLM317KLM31BCN/H

LM319N 1.30

LM320K-5 1 35

LM320K-5.2 1.35

LM320K-12 1.35

LM32QX-15 1.35

LM320K-1B 1.35

LM320K-24 1.35

LM320T-5 1.2S

LM320T-S.2 1.25

LM320T-8 1.25

LM32QT-12 1,25

LM320T-15 1.25

LM320M8 1.25

LM320T-24 1,25

LM323K-5 5.95

LM324N 1.60

LM339N .99

LM340K-5 1 35

LM34QK-G 1.35

LM340K-8 135

LM340K-12 1.35

LM340K-15 1.35

74LS0O74LS0174LS0274LS0374LS0474LS0574LS0874LS0974LSI074LS1174LS1374LS1474LS1574LS2074LS2174LS2274LS2674LS2774LS2874LS3074LS32»4LS3774L5401741842

.29

SN747QNSN7472NSN7473N5N7474NSN7475NSN7476NSN7479NSN74B0NSN7482NSN7483NSN74B5NSN7486NSN7489N5N7490NSN7491NSN7492NSN7493NSN7494NSN7495NSN7496NSN7497NSN74100NSN74107NSN74109NSN74116NSN74121NSN74122NSN74123NSN74125NSN74126NSN74132NSN74136NSN74141NSN74142NSN74143NSN74144NSN74145NSN74147NSN7414BNSN74150NSN74151NSN74152NSN74153N5N74154NSN74155NSN74156NSN74157N

C/MOS

CD4028CO4029C04030CO4035C04Q40CD404IC04042CD4043C04044CD4046CD4047CD* 048C04049CD405OC04051CD4053CD40S6CD4059CD4060C04066CD4068C04069

74C00

74C8S74C9074C9374C9574C10774C15174tl5474C15774C16074Q61

LINEAR

LM340K-18 1.35

LM340K-24 1.35

LM340T-5 1.25

LM340T-6 1.25

LM340T-8 1.25

LM340T-12 1.25

LM340T-15 1.25

LM340T-18 1.25

LM340T-24 1.25

LM358N 1.00

LM370N

LM373N

LM377N

LM380N

LM380CN

LM381N

LM382N

NE501N

NE510A

NE529A

NE531H/V

NE536T

NE540L

NE544N

NE550N

NE555V

NE556N

NE56GB

NES61B

NE562B

NE565N/H

NE566CN

NE567V|HNE570NIM7D3CN/HLM709N/H

1.953.25

1.79

B.CO6004.953.956.006.00

74LS00TTL

74LS47 .89

74LS51 .29

74LS54 .29

74LS55 .29

74LS73 .45

74LS74 .45

74LS75 .59

74LS76 .45

74LS78 .49

74LS83 .89

741S85 1.25

74LS86 .45

74LS90 .59

74LS92 .75

74LS93 .75

74LS95 .99

74LS96 1.15

74LS107 .45

74LS109 .45

74LSI12 .45

74LS123 1.25

74LS12S 89

74LS132 99

74LS136 .49

SH74160N

89

SN74161N

.89

5N74162N

1.95

SN74163N

.69

SN74164N

.69

SN74165N

,69

SN74166N

1.25

SN74167N

1<1S

SN74170N

1.59

SN74172N

600

SN74173N

1?5

SN74174N

.69

SN74175N

.79

SN74176N

79

SN74177N

.79

SN74179N

1.95

5N74180N

,79

SN741B1N

195

SN74182N

.79

SN741B4N

1.95

SN74IB5N

1.95

SN741B6N

0.95

SN741B8N

3.95

SN74190N

1.25

SN74191N

1?S

SN74192N

.79

SN74193N

.79

SN74194N

,89

SN74195N

m

SN74196N

.69

SN74197N

m

SN7419BN

1.49

SN74199N

1.49

SN74S200

4.96

SN74251N

1,79

SN74279N

.79

SN74283N

2.25

SN74284N

3 95

SN742B5N

3.95

SN74365N

.69

5N74366N

69

SN74367N

.69

SN74368N

.69

SN74390N

1.95

SN74393N

1.95

CD4070

C04071

CD4072

C04076

CD4081

CD4082

CD4093

CD4098

MC14409

MC14410

MC14411

MC14419

MC14433

MC14506

MC14507

MCI 4562

MCI 4583

C045OB

C04510

CD4511

C04515

C04518

CD4520

CD4566

74C16374C16474C17374C19274C19374C19574C92274C92374C92574C926BOC9580C97

1.50

LM710N .79

LM711K .39

LM723N/H .55

LM733N 1.00

LM739N 1.19

LM741CN/H .35

LM741-14N .39

LM747N/H .79

LM748N/H .39

LM1310N 2.95

1.MN5DCN/II .59

MC148BN 1.39

MC14B9N 1 39

LM1496N .95

LM1556V 1.75

MC1741SCP 3.00

LM2111N 1.95

LM2901N 2.95

LM3053N 1.50

LM3065N 1.49LM3900N(3401).49

LU3905N .89

LU3909N 1.25

MC5556V .59

8038B 4.95

LM75450N .49

75451CN .39

75452CN 39

75453CN .39

75454CN' .39

75491CN .79

75492CN .89

75493N .89

75494CN .89

RC4136 1.25

RC4151 2.85

HC4194 5.95

RC4195 4.49

74LS13B74LS13974LS15174LSI55

74LS15774LS16074LS16174LS16274LS16374LS16474LS17574LS181741S19074LS19174LS19274LS19374LS1947aS195741S25374LS25774LS25874LS26074LS27974LS36774LS36874LS670

EXCITING NEW KITS

a JE600 HEXADECIMALENCODER KIT

FEATURES:

• Full 8 Dil latdied oulpui lot micio-procassoi use

• 3 Usif Define keys wiih one being bl-si able opei a!ion

• Deoounce nrnnt nrovided lor all 19

DigitalThermometer Kit

~M

" I ^H * LED reaOooi to verify entries

^^^^1 • Easy interlacing with standard

1C connector

• Only +5VDC requtiert lot oneiations

FULL 6 BIT LATCHED OUTPUT—19 KEYBOARO

The JE600 Encoder KeyboarrJ provides (wo separate hexadecimal

digits produced Irom sequential key entries io allow direct prorj-

ramming lor B oil microprocessor or B bit memory circuits. Three

(3) additional keys are provided for user operations wrth one having

a bistable output available The outputs are latched and monitored

with LEO readouts. Also included is a key entry strobe

JE600 $59.95

Hexadecimal Keypad only $10.95

-•witching control for In-

■ Ougl tentor

door/outdoor .. .•Continuous LEO .8" hi. display•Range: -40DF to 199°F / -40^ to 1O0°C•Accuracy: ±1° nominal•Set for Fahrenheit or Celsius reeding■Sim. walnut case - AC wall adapter incl.• Size: 3-1/4"Hx6-5/8"Wx1-3/8"D

JE300 $39.95

DISCRETE LEDS

.200' HiXC556R redXC556G greenXC556V yellowXC55BC cleat

.200" dilXC22R redXC22G greenXC22Y yellow

.no- mi.

MVIOB red 4

.015- die.MV50 red 6

INFRA-RED LED

1/4"«IM-x1/t6-|M 5/S1

satMi

4/SI4/S1

5;SIMl

4/SI

.121- nil.

XC209R redXC209G greenXC209V yellow

.1(5- dil.XC526R redXC5266 greenXC526Y yellowXC526C clear

.110- die.XC1IIR redXC111G greenXC11IV yellowXC1I1C clear

5,S14/114/SI

5/S14/J1

4/SI4/SI

5/S14/SI

4/S14/SI

DISPLAY LEDS

TIMEX T1D01

LIQUID CRYSTAL DISPLAY

CUSS II

FIELD EFFECT

4 DIGIT - .5'- CHAHACTERS

THREE ENUNCIATORS

2.00" X 1.20" PACKAGE

INCLUDES CONNECTOR

TIOOl-T.ansmiiiivg S7.9S

TIOOIAfltflactivs 8.2S

TYPE

MAN 1MAN 2MANSMAN 4MAN7GMAN7YMAN 72MAN 74MAN 82MAN 84MAN 3620MAN 3530MAN 3640MAN 4610MAN 4540MAN 4710MAN 4730MAN 4740MAN 4510MAN 4840MAN 6610MAN 6630MAN 6640MAN 6650MAN 6660MAN66S0MAN 6710

KIIJUIITY I

Common Anode-red5 x 7 Dot Maihx-redCommon Calhode-redCommon Cathode-redCommon Anode-greenCommon Anode-yellowCommon Anode-redCommon Calhode-redCommon Anode-yellowCommon Cathode-yellowCommon Anode-orangeCommon Anode-orange » 1Common Calhode-orangeCommon Anode-orangeCommon Cathode-orangeCommon Anode-redCommon Anoda-red ± 1Common Cathode-redCommon Anode-yellowCommon Cathode-ye HowCommon Anode-orange-D 0Common Anode-orange ^ 1Common Calhode-orange-0 0.Common Cathode-orange t 1Common Anode-orangeCommon Cathode-a rangeCommon Anode-rod-u.D.

TYPE

MAN 6730

MAN 6740

MAN 6750

MAN 6760

MAN 6780

DL701

OL704

DL707

DL728

DL741

DL746

DL747

0L749

0L750

DL33B

FNO70

FN0358

FN0359

FND503

FNO507

5082-7730

HOSP-3400

HDSP-3403

5082-7300

5082-7302

5082-7304

5O62-7340

POUfllTY

Common Anode-red ± 1Common Calhode-red-D 0Common Cathode-red t 1Common An ode-redCommon Cathode-redCommon Anode-rod = 1Common Calhode-redCommon Anode-reJCommon Cathode-redCommon Anode-redCommon Anode-red t 1Common Anode-redCommon Calhode-red i 1Common Cathode-redCommon Cathode-redCommon CathodeCommon Cathode ± 1Common CathodeCommon Cathode (FN 0500)Common Anode (FND510)Common Anode-redCommon Anode-redCommon Cathode red4 * 7 sgl. Digil-HHDP4x7Sgl Digft-LHOPOverrange character [ ± 1)4 x 7 Sol. Oipit-Hexadetimal

RCA LINEAR

CA3013TCA2023TCA3035TCA3039TCA3046NCA3059NCA3060NCA3080TCA30B1N

2.15 CA3082N

2.56 CA3083N

2.48 CA3086N

1.35 CA3089N

1.30 CA3130T

3.25 CA3140T

3.25 CA3160T

.65 CA3401N

2.00 CA3600N

CALCULATOR

CLOCK C

CHIPS/DRIVERS

MM5309

MM5725

MM5311

MM5738

DM6B64

MM5369

MM5387/1998A

C.A LED driver

1 SO

8 pin LP14 pin LP16 pin LP18 pin LP20 pin LP

14 pin ST16 pin ST18 pin ST24 pin ST

8 pin SG14 pin SG16 pin SG18 pin SG

I pin WW10 pin WW

14 pin WW16 pin WW

18 pin WW

1-24 25-49 50-100

IC SOLOERTAIL — LOW PROFILE (TIN) SOCKETS

MC1408L7

MC1408L8

MC1439L

MC3022P

MC306IP

MC4016I74416)

MC4024P

MC4O40P

MC4044P

$4.95

5752.952.953.507.50

1-24

22 pin LP S 37

24 pin LP 38

28 pin LP -45

.27 36 pin LP 60

a> SOLOERTAIL STAHDAHD (TIN) «P*"LP ra2B pin ST t .9936 pin ST 1.3940 pin ST 1.59SOLOERTAIL STANDARD (GOLD)

2* pin SG S -70

25-49 50-100

28 pin SG36 pin SG

40 pin SG

1.65

WIRE WRAP SOCKETS(GOLD) LEVEL #3

22 pin WW $ 9524 pin WW 1 0528 pin WW 1.4036 pin WW 15940 pin WW 1 75

1/4 WATT RESISTOR ASSORTMENTS - 5%

10 OHM27 OHM63 OHM

I? OHM 15 OHMJ3 OHM 39 OHM

8? OHM 100 OHM

18 OHM47 OHM?0OHM

22 OHM56 OHM50 OHM

IBOOHM 220 OHM ,'70 OHM 330 OHM 390 OHM4 70 OHM 560 OHM 680 OHM 820 OHM

220K560KI 5M3.9M

100K270K

120X330K

8?0K

ASST. BR Includes Resistor Assortments 1-7 (350 PCS.)

SO PCS

$1.75

50 PCS

1.75

SO PCS

1.75

SO PCS

1.75

SO PCS

1.75

SO PCS

1.75

so pes 1.75$9.95 ea.

$10.00 Min. Order - U.S. Fundi Only Spflc Sheets - 25t!

Calif. Residents Add 6% Seles Tex 1979 Catalog Available - Send 4U stamp

Postage-Add 5% piusSI Insurance lif desired I

PHONE

ORDERS

WELCOME

(415) 592-8097

MAIL ORDER ELECTRONICS - WORLDWIDE

1021 HOWARD AVENUE. SAN CARLOS. CA 94070ADVERTISED PRICES GOOD THRU SEPTEMBER

AV-5-9100

AV-5-9200

AY-5-9500

AY-5-237S

HD0165

74C922

TELEPHONE/KEYBOARD CHIPS

Push Button Telephone Dialler

Repertory Dialler

CMOS Clock Generator

Keyboard encoder (86 keys)

Keyboard Encoder (16 keys)

Keyboard Encoder (16 keys)

SU.9514.954.9514.957.955.95

ICM7045ICM7205ICM7207ICM7208ICM7209

ICM CHIPS

CMOS Precision TimerCMOS LED Stopwatch/TimerOscillator ControllerSeven Decade CounterClock Generator

24.9519.95

7.5019.95

6.95

NMOS READ ONLY MEMORIES

MCM6571 128 X9X 7 ASCII Shitted Willi Greek 13.50

MCM6574 126 X 9 X 7 Math Symbol s Pictures 13.50

MCM6575 128 X 9 X 7 Alphanumeric Control 13.50

Character Generator

MISCELLANEOUS

TL074CN Quad Low Noise bi-let Op Amp

TL494CN Switching Regulator

TL496CP Single Switching Regulator

11C90 Divide 10/11 Prescalnr

95H90 Hi-Speed Divide 10/11 Prescaler

4N33 Photo-Darlington Opto-lsolalor

MK50240 Top Octave Freq. Generator

OS0026CH 5Mhz 2-phase MOS clock driver

111.308 .27" red num. display w/integ. logic chip

MM5320 TV Camera Sync. Generator

MM5330 4K Digit 0PM Logic Block ISpecisll

LD110/111 3Vj Digit A/D Convener Set

2.494.491.7519.9511.953.9517.503.7510.5014.953.9525.00/set

LITRONIX ISO-LIT 1

Photo Transistor Oplo-lsolator(Same as MCT 2 or 4N25)

2/990

SN 76477

SOUND GENERATOR

Generates Complex Sounds

Low Power - Programmable

3.95 each

TV GAME CHIP AND CRYSTAL

AY-3-8500-1 and 2.01 MHZ Crystal (Chip & Crystal - nc .

includes score display, 6 games and select angles, etc 7.95/SBl

XR205XR210XR215XR320XR-L555XR555XR556XR567CPXR567CTXR1310P 1.30XR1468CN 3 85XR1488 1.391.39

S8 404.404.401.S51.50

1.25

EXAR

JE2206KA 14.95

JE2206KB 19.95

XR1800 3.20

XR2206 4.40

XR2207 3.85

XR2208 5.20

XR2209 1.75

XR2211 5.25

XR2212 4.35

XR2240 3.45

XB2556XR2567XR3403XR4I36XR4151XR4194XR4202XR4212XR4558XR4739XR4741

3202991.25

1 25

2 854.933602 05

.751.151.47

TYPEIN746

1N7S1

IN752

IN753

1N7S4

IN757

1N7S9

1N9S9

1N965

1NS232

IN5234

IN5235

1N5236

1N52*2

IW5245

1N456

1N4S8

1N485A

1N4001

DIODES

VOLTS W

3.3 400m

5.1 400m66 4Q0m

6.2 400m6.8 400m9.0 400m

12.0 400m

8.2 400m

15 400m

5.6 500m

6.2 500m

6.8 500m

7.5 500m

12 500m

IS 500m

PRICE

4/1 004/1.00

180 10m

50PIV 1 AMP

6/1 00

6/1.005/1.0012/1.00

TYPE

1N40021N40031N40041N40O51N40061N40071N360O1N41481N41541N43051N47341N47351N47361H473B1N47421N47441N11831N1184INI 1651N11861N11B8

VOLTS W100 PIV 1 AMP

200 PIV 1 AMP400 PIV t AMP600 PIV 1 AMP800 PIV 1 AMP1000 PIV 1 AMP50 200m75 10m35 10m

PRICE

12/1.0012/1.0012/1 0010/1 0010/1.0010/1 006/1.0015/1.1

12 1wIS 1w50 PIV 35 AMP

100 PIV 35 AMP150 PIV 35 AMP200 PIV 35 AMP400 PIV 35 AMP

SCR AND FW BRIDGE RECTIFIERS

C360 15A ru 400V SCH{2N1W9)

C38M 3SA (a 600V SCfl

2N2328 1.6A@ 300V SCR

MOA 980-1 12A (rf 50V FW BRIDGE REC.

MDA9B0-3 12AiTi 200V FW BRIDGE REC

C106B1

MPSA05

MPSA06

TIS97

TIS98

40409

40410

40673

2N918

2N2219A

2N2221A

2N2222A

PN2222 Plastic

2N2369

2N2369A

MPS2369

2N24B4

2N2906

2N2907

PN2907 PlasKc

2N2925

MJE2955

2N3053

.50

.30

5/1.00

6/1.DO

6/1.00

5/1.007/1-005.-1 004/1.005/1.004/1.004/1.005/1.007/1.005/1.00

Transistors

2N3055

MJE3055

2N3392

2N3398

PN3567

PN3568

PN3569

MPS3638A

MPS3702

2N3704

MPS3704

2N3705

MPS3705

2N3706

MPS370S

2N3707

2N3711

2N3724A

2N3725A

2N3772

2N3823

2N3903

CAPACITOR

5/1.005/1.003/1.004/1.004/1.005/1.005/1.005/1.005/1.005/1.005/1.005/1005/1.005/1 005/1 0065

^U30_

2N39042N3905

2N39062N40132N4123PN4249PN42502N44002N44012N44022N44032N44092N50862N50872N50882N50892N5129PN5134PN51382NS1392N52102N5449Si

6/1004/1 004/1.004/1.004/1004/1.004/1 005/1-004/1004/1 004/1.004/1.00

10 pi22 pi47 pf

100 pi220 pi470 nl

001ml

.0022

,0047ml

,01ml

.1/3SV15/35V

.22/35V.33/35V.47/35V68/35V1.0/35V

.47/50V

1.0/50V

3 3/50V

4.7/25V

10/25V

10/50V

22/25V

22/50V

47/25V

47/50V

10O/25V

100/50V

220/25V

220/50V

470/25V

1000/16V

2200/16V

50 VOIT CERAMICDISC CAPACITORS_ iffiL.04 .03 OOVF04 .03 0O47MF.04 03 OI^F.04 03 022^F.04 .03 047>lF.04 .035 ,VF100 VOLT MYLAH FILM CAPACITORS.10 .07 ,022ml047ml

CORNER

.05 .04 .035

12 .09 075

.10

.07

■22ml ,33 24-20% DIPPED TANTALUMS ISOLI01 CAPACITORS

-28 .23 .17 1.5/35V .30 ,2

.20 -23 .17 22/25V 31 2

28 .23 .17 3.3/25V .31 .2

.28 .23 .17 4.7/25V .32 ,21

.28 .23 .17 6B/2SV .36 .3'

I5/25V .63 .51

.26

.23

.17

MINIATURE ALUMINUM ELECTROLYTIC CAPACITORSW»l Ltwl H.dl.l L»d

.15 .13 .10 47/25V .15 .13

.16 .14 .11 .47/50V .16 .14

.14 .12 .09 1.0/16V .15 .13

• .15 .13 .10 1.0/25V .16 .14

-15 .13 10 1.0/5OV .16 14

16 .14 .12 4.7/16V .15 .13

.17 .15 .12 4.7/25V 15 13

.24 .20 .18 4.7/50V 16 14

.19 .17 .15 10/16V .14 12

.25 .21 ,19 10/25V 15 13

.24 .20 .18 10/SQV 16 .14

.35 .30 -28 47/50V .24 .21

.32 .28 .25 10O/16V .19 .15

.45 .41 .38 100/25V .24 .20

33 .29 27 10O/50V 35 30

.55 50 -45 220/16V ,23 .17

.70 .62 .55 470/25V .31 .28

232 BYTE September 1979

Circle 200 on inquiry card.

f Transistor Checker

— Completely Assembled —— Battery Operated —

The ASI Transistor Checker iscap-able of checking a wide range oftransistor types, either "in circuit"or out of circuit. To operate,simply plug the transistor to bechecked into the front panelsocket, or connect it with the alli-gator clip test leads provided.The unit safely and automaticallyidentifies low, medium and high-power PNP and NPN transistors.Size: 35t" x 6*/4" x 2""C" cell battery not included.

Trans-Check s 19.95 ea.

Custom Cables & Jumpers

Part No.

DB25P-4-PDB25P-4-SDB25S-4-S

DJ14-1

DJ16-1DJ24-1DJ14-1-H

DJ16-1-16DJ24-1-24

DB 25 Series Cables

Cable Length Connectors Price

4 Ft. 2-DP25P S!5.95ea.

4 Ft 1-OP25P/1-25S S16.95 ea.

4 It. 2-DP25S $17.95 ea.

Dip Jumpers

11t

i it.

1 ft.

1 it.11t

i n

1-14 Pin1-16 Pin1-24 Pin2-14 Pin2-16 Pin2-24 Pin

$1.59 ea1.79 ea.2.79 ea2.79 ea.3.19 ea4.95 ea.

For Cuitom Cablet ft Jumpers. 8m JAMECD 1979 Catalog lor Priclnp.

CONNECTORS

25 Pin-D Subminiature

DB25P las pictured) PLUG (Meets RS232) S2.95

DB25S SOCKET (Meets RS232) 13.50

DB51226-I Cable Cover lor DB25P or DB25S $1.76

PRINTED CIRCUIT EDGE-CARD

ISfi Spaano-7in Double RaM-Out — Biluracieg Cooiscts — Fits 054 to 070 PC CaiOi

15/30

18/36

22/44

50/100 (.100 Spacing)

50/100 (.125 Spacing)

PINS (Solder Eyelet)PINS (Solder Eyelet)PINS (Solder Eyelet)PINS (Wire Wrap)PINS (Wire Wrap)

S1.9S$2.49$2.95$6.95R681-1 $6.95

4-Digit Clock Kit

' Bright .357" ht. red display

' Sequential flashing colon

' 12 or 24 hour operation

' Extruded aluminum case (black)

' Pressure switches for hours, minutes & hold functions

' includes all components, case and wall transformer

i Size: 3V* :

IV. x 1V«

JE730 $14.95

Jumbo 6-Digit Clock Kit

» Four .630"ht. and two .3M"ht.common anode displays

* Uses MM5314 clock chip

* Switches for hours, minutes and hoi-

* Hours easily viewable to 30 feet

* Simulated walnut case

* 115VAC operation

* 12 or 24 hour operation

* Includes all components, case and w

* Size: 6V* x 3to x IV.

JE747 $29.95

. cath-

ock chip

nutes

JE701

• Bright .300 hiode display

• Uses MM5314 cl

• Switche* lor hourand hold modes

• Hrs. easily viewable to 20 ft.

• Simulated walnut case

• 115 VAC operation

• 12 or 24 hr. operation

• Inet. all components, case &wall transformer

• Size:

< 3-1/8"

IK"

6-Digit Clock Kit $19.95

REMOTE CONTROLTRANSMITTER ft RECEIVER

$19.98

Digital Stopwatch Kit

* Use Intersil 7205 Chip

* Plated thru double-sided P.C. Board

* LED display (red)

* Times to 59 mln. 59.59 sec. with auto reset

* Quartz crystal controlled

* Three stopwatches in one: single event, splitnmulatlve] 4. taylor (sequential timing)

L * 5lz<

s 3 pern it f: batteries11 4.5" x 2.15" x .90"

je900 $39.95

MICROPROCESSOR COMPONENTS

8212S214

821682248228

B2238238825182538258H2578259

-BOIM/HMDA SUPPORT DEVICES-CPU

8-Bit InpuUOutpulPriority Interrupt ControlBi-Directional Eii.-s DrrvorClock Generator/DriverBus Driver

System Controller/Bus DriverSystem ControllerProj. Comm. 1/0 (USAHT)Proo Interval TimerProrj. Periph 1/0 (PPI)Prog. DMA ControlProg. Interrupt Control6800/6800 SUPPORT DEVICES—MPU

MPU with Clock and FUm12BXB Static RamPenph Inter Adapt (MC6B20)Prionty Interrupt Controller1024X8 Bit ROM (MC68A30-BIAsynchronous Comm. AdapterSynchronous Sena! Data Adapt.0-600 bps Digital MODEM2400 Ops Modulator

-MICROPROCESSOR MANUALS-

M-Z80 User Manual

M-CDPtoO? User ManualM-2650 User Manual

-ROM'S-

2513(2140} Character Generaior(upper case)

2513(3021) Character Generator^lower case)

2516 Character Generator

MM5230N 2048-Bit Read Only Memory

SH.9524.955.957.1912.9514.957.959.95

Quad3-SU1eB MICROPROCESSOR CHIPS—MISCELLANEOUS -

ZB0{78DC) CPUZB0A(780-1) CPUCDP1802 CPU2650 MPU

6502

lil MPU w/clock, RAM. 1/0 linesPS0B5 CPU

TMS9900JL 16-Bil MPU w/hardware, multiply

4 divide SHIFT REGISTERS

$19.9521.9519.9519.9511.9519.951995

1101

1103

2101(8101)

2102

21L02

2I11(811t)

2112

2111

2114L

2114-3

2114L-3

5101

5280/2107

74B9

74S200

93121

UPD111

(MK1027)UP0416

(MK1116)IMS4041-

45NLTMS40452117

256X1

1021X1

255X4

1024X1

1024X1

256X1

256X4

1024X4

1024X4

1024X4

1024X4

256X4

4096X1

16X4

256X1

256X1

4K

MM500H

MM503H

MM504H

MM506H

MM510H

MM5016H

2504T

2518

2522

2524

2525

2527

2528

2529

2532

2533

3341

74LS670

Dual 25 Bit DynamicDual 50 Bit DynamicDual 15 iliI SialicDual 100 Bit StaticDual 64 Bit Accumulator500*512 Bit Dynamic1024 DynamicHex 32 Bit StaticDual 132 Bit Static512 Static1024 DynamicDual 256 Bit StaticDual 250 StaticDual 240 Bit SusieQuad 60 Bit Slatie1024 StaticFilo

- RAMS

Static

Dynamic

Static

Static

Static

Static

Static MOS

Static 450ns

Sialic 450ns law power

Static 300ns

Static 300ns low power

Static

Dynamic

Static

Static Trisiaie

Static

Dynamic 16 pin

Dynamic 16 pin

Sialic

Static

Dynamic 350ns(house marked)Dynamic

14.9514.95

1702A

2716INTEL

TMS2516

<271B)

TMS2532

270B

2716 T.I

82S23B2S115B2S123741B6

2048

" PROMS

FAMQS16K' EPROM

I6K- EPROM

'Requires single i-5V power supply4KX8 EPROM

tin EPROM

16K" EPROM

'Requires 3 voltages.

2048) 1024) 25632XB409632X8

A-Y-5-1013 30K BAUD

EAM0S

Tristale Bipolar

Open C Bipolar

Open Collector

Bipolar

Tristale

TTL Open Collector

TTL Open Collector

Static

12V

$5.9559.9549.95

89.9510.9529.95

9.953.952.95

CONTINENTAL SPECIALTIES

Proto Board 203

*75.00

ModalNumbar

PB-6PB-100PB-IOt

LlWlH

(Inchail Price

6.0 « 4.5x1.4 S1S.95

6.0x4.5x1.4 SU.95

6.0x4.5x1.4 $22,95

Proto Board 2034

9124.95

Modal LxWxH

number llnclteil Pried

PB-102 7.0x4.5x1.4 J251S"

PD-1IB 9.0x6.0x1.4 $44.95

PB-104 9.8x8.0x1.4 S54.95

62-Key ASCII Encoder Keyboard Kit

The JE610 62-Key ASCII Encoder KeyboardKit can be interfaced into most any com-puter system. The JE610 Kit comes com-plete with an industrial grade keyboardswitch assembly (62 keys), IC's, sockets,connector, electronic components and adouble-sided printed wiring board. Thekeyboard assembly requires +5V @ 150mAand —12V @ 10mA for operation.

& JE610

FEATURES:

•60 Keys generate the full 128 char-acters, upper and lower case ASCIIset

• Fully buffered

• 2 user-define keys provided forcustom applications

• Caps lock for upper case onlyalpha characters

•Utilizes a 2376 (40 pin) encoderread only memory chip

• Outputs directly compatible withTTL/DTL or MOS logic arrays

• Easy interfacing with a 16-pin dipor 18-pin edge connector

JE610 $79.95

JE200

REGULATED POWER SUPPLY $&

JE20Q $14.95

5V-1 AMPPOWER SUPPLY

"Uses LM309K

• Heat sink provided*PC Board construction

• Provides a solid 1 amp@ 5 volts

*Can supply up to ±5V.

+ 9V and +12V with

JE205 Adapter*l neludes components,

hardware & instructions

• Size: 3,/5"x5"x2"H

JE205

g

ADAPTER BOARD-Adapts to JE200-±5V,±9Vand±12V

■DC/DC converter w/

+ 5V input•Tortodal hi-speed

switching XMFR'Short circ.protection■PC Brd. construction■Piggy-back to JE200

board•Size:31/$"x2"x9/16"h

JE205 $12.95

$10.00 Min. Order - U.S. Funds Only Spec Sheets - 254

Calif. Residents Add 6% Sales Tax 1979 Catalog Available -Send 41 i stamp

Postage — Add 5% plus$1 Insurance (if desired)

PHONE

ORDERS

WELCOME

(415) 592-8097

FREE

1979A

CATALOG

Jameco

MAIL ORDER ELECTRONICS - WORLDWIDE1021 HOWARD AVENUE, SAN CARLOS, CA 94070

ADVERTISED PRICES GOOD THRU SEPTEMBER

The Incredible"Pennywhistle 103"

$139.95

Kit Only

The PsnnywhliUi IDS is capable of recording data lo and from audio tape wilhoul

critical speed requirements lor the recorder and il is able lo communicate directly with

another modern and terminal lor telephone "hamming" and communications. In

addition, it Is tree of aiiical adjust mentsand is bulit with non-precision, readily available

pans.

Diti Trentmlulon Method Frequency-Shift Keying, full-duplex (hall-duplei

selectable).

Miirmum Dili Rite 300 Baud.

Dili Format Asynchronous Serial (return to mark level required

between each character).Receive Channel Frequencies- . ..2025 Hi for space; 2225 Hi lor markTrerwmlt Channel Frtquentlai ..Switch selectable Low (normal) = 1070 space,

1270 mark; High = 025 space, 2225 mark.

Receive Senilthrth; --46 dam accousiically coupled.

Trinim.1L.ml -15 dbm nominal. Adjustable Irom -6 dbm

lo-20 dbm.Receive Frequency Tolerance ...Frequency relerence automatically adjusts lo

allow lor operation between 1800 Hz and 2400 Hr.Digital Data Interlace EIA RS-232C or 20 mA current loop (receiver is

opto isolated and n on -polar).

Power Requirement! 120 VAC, single phase. 10 Watts.

FTiyalcal All components mounl on a single 5" by 9'

printed circuit board. All components included.Requires a VOM. Audio Oscillator. Frequency Counter and/or Oscilloscope to align.

TRS-8016K Conversion Kit

Expand your 4K TRS-80 System to 16K. Kitcomes complete with:

■ 8 each UPD416-1 (16K Dynamic Rams) 250NS* Documentation for conversion

TRS-16K

$75.00

COMPUTER CASSETTES

.6 EACH 15 MINUTE HIGHQUALITY C-15 CASSETTES

. PLASTIC CASE INCLUDED12 CASSETTE CAPACITY

. ADDITIONAL CASSETTESAVAILABLE #C-15-$2.95 sa

CAS-6

$14.95

(Case and 6 Cassettes)

SUP 'R' MOD II

UHF Channel 33 TV Interface Unit Kit

Wide Band B/W or Color System

* Converts TV to Video Display forhome computers, CCTV camera,Apple II, works with Cromeco Daz-zler, SOL-20, IRS-80, Challenger,etc.

MOD II is prettified to Channel 33(UHF}.

* Includes coaxial cable and antennatransformer.

MOD II

$29.95 Kit

Function Generator Kit

• Provides 3 basic waveforms:sine, triangle & square wave

• Frequency range Irom 1 Hz to100K Hz

• Output amplitude from 0-volts toover 6 volts (peak lo peak)

• Uses a 12V supply or a ±6V splitsupply

• Incl. chip, P.C. board, compo-nents and inslructions.

JE2206B $19.95

IDEAL FOR TRS 80 CASSETTE CONTROLLER

"Plug/Jack interface to anycomputer system requiringremote control of cassettefunctions"

The CC100 controls cassettemotor functions, monitorstape location with its internalspeaker and requires nopower. Eliminates the pluggingand unplugging of cables dur-ing computer loading opera-tion from cassette.

#cc

$29.50

Micro-MiniatureJoystick

• 2 each 100K pots (Linear Taper)

• Printed Circuit Board Mount

• Size: 1"x 1-3/16"x 1-3/16"

Micro-Miniature Joystick

$4.95/

Circle 201 on inquiry card.

BYTE Sepeember 1979 233

Save $ on TRS-80 Products

*\ TREMENDOUS> SAVINGS ON1?r TRS-80 SYSTEMS

>

Complete system includes:TRS-80 Level II, w/our48KRAM, Dual MPIDisk Drives, and the APPARAT DOS+ soft-ware ($2500 value), only $2049. Line printerand desk options available.

SUPERDISK

TF-7D Micropolis Largest capacitymini floppy, up to 195 Kbyteson 77 tracks with 77TK DOS+ $699

Send for FREECatalog

A Complete FamilyOf Disk DrivesTo ChooseFrom . . •

In Stock

TF-1 Pertec FD200, 51A", 40 track use both sides $379

TF-3 Shugart SA400, 51A", 35 tracks same as tandy $389

TF-5 MPI 5%" 40 track door lock and auto diskette $379

ejection

TDH-1 Pertec Dual Head mini-floppy 35 track same $499

capacity as 2 drives

All disk drive systems come complete with power supply andchassis

• Two drive cable= $25 • Four drive cable= $35

PRINTERS PRINTERS PRINTERS PRINTERS

LP779 Centronics 779w/tractorsLP700 Centronics 700LP701 Centronics 701NEC Spinwriter

$1099

$1175$1759$2499

CENTRON

LP702 Centronics 702 $1899

LP703 Centronics $2540

LP1 Centronics P1 $ 399

Centronics cables $ 39

Add-on Disk Drives

DOES NOT INCLUDE POWER SUPPLY OR CHASSIS

• Pertec FD200 or MPI B-52

• Shugart SA400 (unused)

• Pertec Dual Head

$272.00$282.00$399.00

NEW PRODUCTS

• Small System RS232 Interface $ 49.00

• Expansion Interface w/32K $499.00

• AC Line Interference Eliminator $ 18.95

• AC Isolator (6 connectors) $ 45.95

• Telephone Interface $179.95

• Verbatum 5" soft sector Diskettes $ 3.39

IMPROVE TRS-80

PERFORMANCE WITH

NEWDOS+

Over 200 modifications,corrections and enhance-ments to TRS DOS.Includes utilities. Available intwo versions:35 Track version $9940 Track version $110

All prices cash discounted.Freight FOB/Factory

Memory

16KM 16KRAM KitComputer $74Expansion Interface $78

«T

/MCROCO/VIPUrER

TECHNOLOGYINCORPORATED

2080 South Grand Ave.

Santa Ana, CA 92705

(714) 979-9923

Circle 277 on inquiry card.

Software

• Accounts Receivable $39

• Inventory Control $39

• Job Entry/Status $75

• General Ledger $79

• Game Diskette $19

• AJA Word Processor $75

6000 E. Evans Ave., Bldg. 2Denver, CO 80222(303) 758-7275

p pa rat, Inc.

Circle 15 on inquiry card.

CaUFornia DiqiTAl

Post Office Box 3097 B • Torrance, California 90503

Sankyo MagneticCard Reader

These Sankyo I/O units are capable of storing and retrieving over

400 characters of data in under two secords.

The flexibility of this device lends itself t'o numerous applications.]IAs an input reader to a computerized security system, the com-Ijputer has the ability of identifying the card holder and admitting1 only those individuals who are authorized to enter the premises[■during specified time frames. The device is also suitable for[maintaining customer information files, or any other application

where small amounts of information must be quickly entered into

a data processing system.

Accepts 2" by 4" HP style mag-cards. (Similar to bank cards. )

Motorized feeder pulls the magnetic card across the four channelj read/write head. NEW surplus, original cost $200. Full documentation

CONNECTORS

your choice

f—i HOCO | DB2SP

r~" ^ mile plus It hooi

I ■ ' _j DB25S female

MUUUUMJL 3.95

iuuuuiu.

H j ?

o<-

Qty. ft. male hd.10 Hi 2.45 1.1525 115 2.25 1.05100 2.15 1.90 .15WO 2.251.00 JSIK 1.07 1.37 .73

EdgeCannae tors

fatal HMff .1251.250

Iks.I v/w.l2SctattrsAltilr lold.rl.II.140,o.

specials

22/44 Klai lJ.Ht.15t"25/50 aaMartia .150"

38/72 wldap.lt W/W.155

GOLD

100 PIN

IMSAI/ALTAIR

• 3.05 3/1 I 00•4.05 3/(13.00•5.M 3/(15.00

(1.55 3/15.00il.09 3/(2.00

• 1.15 3/(5.00

S-100 Mother BoardQuiet

HEXADECIMAL KEYBOARD

MaxISwitch hexadecimal kayboawds tindesigned for <4*J,4j 85

microcomputer syslema that r«qulr«4-blt output «;'i/ •■■■^T*

In eUuidard hex coda.

Each assembly constats of 18 hermeti-

caily sua led road switches and TTL "

shot" debounco circuitry.

Reliable low friction acatal raaln

plungers a/a cradltad (or the amooth

operation and long Ufa of this premium

keyboard.

Rsqulraa single + 5 volt aupply.

'24.88

^s ^UNIVACKEYBOARD

Tht limoui Spoirry Univac 1710 Holianiti keyboard aiaambty15 now i.niBbK Irom California Industrial for only $24 f!3The iQoii compular input drrica 'or accountants andmathernilicunjj The mimetic keyi art placad On Ih* lowerthiao rowi Id rttcmbl* ■ fen Hay adding mac nine Thislor mil allows one handed numeric date entry.

Complete with '

TEN

_IPX

50

**A% Cxn^nh9 Certified Digital4^L SCDtCTl CASSETTES

*'3?5 ""*ND Wort drop. BIT!

wTs

TELETYPE MODEL 4 3

Ev.ti If w. biva t. gIvt tk.M.way, w.t. gal.f to ship mora43'i la 1979 than t>a anragatatf til oar compalltors.

Model 43AAA

«CH _JL

*925. 875.

TTL)

85a

825.

R5-232 Interface"*." nd»7S0O ..fjpf.i ' Wt M

FREE

PLASTIC LIBRARY CASE

with purchase of each box of ....' itlm mInl-dlskeWei. 55 value.

BOX of 10

IMOduLATOR

Trio Atari R.F. Modulatorallows computer data to bedlaplayed directly upon yourIstlng television system,| Thla unit converts the sig-nal Irom the Apple II andother video sources Intotelevision frequencies.Operates Irom single 5vol I supply. Complete^Jit»e_^*"* ^- «Hh metal case, matingVrjjV*'^^——""^ R.F. connector and 15feet ol coax cable. Schematicsand Instructions Included.

KETTES

SPGCiflL

APPLE (I

IBK MEM OR

COLOR • GRAPHICS* SOUND

$1024

PLUS SH1PPIHC

Mff.aui.Retail....

•1195

Diskettes

| 8lnchSoft(IMH8 inch 32 sectorMini Soft sec.Mini 10 sectorMini 16 sector

hugart Associates

SA800-R Floppy Disk Drive

The most cost effective way to store data proc-essing information, when random recall is aprime factor. The SA800 is fully compatiblewith the IBM 3740 format. Write protect cir-cuitry, low maintenance & Shugart quality.

>44950

KEYBOARD

ASCII ENCODED

KEYTRONICASCII & ASCIIcomplement.♦Ten key data pad 1♦ Cursor controls♦Six user switches|

* Alpha L ock*Auto repeat♦Single 5 volt.

♦ Glass reed.

NEW

TRS-80$|I APPLE II

16k memory (8) 4116's

• As you may be aware, publishersrequire advertisers to submit theirad copy 60 to 90 days prior to "press"date. That much lead time in a volatile market place,such as memory circuits, makes it extremely difficultto project future cost and availability.To obtain the best pricing on memory we have madevolume commitments to our suppliers, which in turnaffords us the opportunity to sell these circuits at themost competitive prices. Please contact us if youif you have a demand for volume state of the art mem-ory products.

STATIC

21L02 450nS.21L02 250nS.2114 lKt4 4502114 lKf.4 3004044 4Kxl 450

4044 4Ktl 250

4045 1Kx4 4504045 1Kc4 2505257 low pow.

1-31 32-99 100-5C -999 1K+

1.19 .99 .95 .90 .85

1.49 1.39 1.25 * *

5.95 5.50 5.25 4.75 4.50

8.95 8.50 8.00 * *

5.95 5.50 5.25 * *

9.95 9.50 9.00 * *

8.95 8.50 B. 00 * *

9.95 9.50 9.00 * *

5.95 5.50 5.00 4.80 4.60

SPECIAL CIRCUITS

Z80A 4 MHz.

8080A CPU

8085

8086 Intel 16 bits

TMS9900 16 bits

24.95

9.95

22.50

AY5-1013A UART 4.95Floppy Disc ControllersWD 1771 single D. 39. 95WD 1781 Double D 65. 00WD 1791 D/D3740 *

64+4.009.00

E PROMS 1-15 16-63

1702A 2K 4.95 4.50

2708 8K 9.95 9.50

2716 5vl6K 39.95 35.00

2716 TI 24.88 20.00

2532 * *

^ !E3

PORTABLE DATA ENTRY SYSTEM

These used data terminals were originally designed for chain store inventory con-trol and order entry systems. The operator enters the inventory control number,merchandise on hand and the unit price. After all pertinent data has been entered intothe recorder, the main warehouse is telephoned, the handset is placed in the acousticcoupler and all the recorded information is transmitted back to the master computer.With a little Imagination and one of these portable entry systems, you should be ableto exchange programs and computer information with associates across the country.Ail units were removed from service in working condition. Original cost $2,500.Each system comes complete with:

•Portable Cassette Drive Unit -Five Gould "D" NiCads "DB25 Cable

■Removable Entry Keyboard ■Acoustical Coupler ..Shoulder starp

with LED Display "Battery Charger "Full Documentation

*-98 188 .81.73.68 |

SPDT Miniature Toggles

7101 CM 0N-N0NC-0N7107 jbt ONOFF(mnt.ON) I7101 CK ON(momint.ON)

Rocker JBT DPDT

Rotary 3P-4Poi.

Rotary 3P-6-Pos.

Pnih B (NO.) $ 39ei. 4/S1

DIP Switch

DISCOUNT

HSTI1 WO

UUire Wrap Center

It'a not offen that California Digital ven-tures into the distribution of consumer pro-ducts, but we have reaently come accrosea product that appears so unique that we just had to add itto our product line. This is the System X-10 manufacturedby the BSR turntable company. This apace age system will re-motely control any light or appliance in your home or office. Command sig-nals are transmitted from the command console over your existing wiring.From your bed or easy chair you can control up to 16 different electrical de-vices inside and outside your home. Use the System X-10 to control yourstereo, television or any light fixture on the premises.

The basic sampler package comes complete with command console, batteryoperated ultrasonic controller, one each of the appliance module, lamp mod-ule and wall switch. The basic package is priced at only $99.50 Additionalmodules are available for $13. 95 each. f

IC SOCKETS

wlr. wrap». 25 SO

low profile

i«. 25 SO

17< 16 IS

37<36 35

IS 17 16

31 37 34

19 IS 17

99 93 IS

36 35 34

169 1SS 119

63 60 58

£.t KYNARwiSr

.98 900 1,000 11,000

*9. SIS. (105.

SS9.95 -f

BW630 '

(213)679-9001

19 nil inquiry i aid

COMPUCRUISE

Put a computer inyour car, which givesyou the most effec-tive and functionalcruise control everdesigned, plus com-plete trip computing,fuel management sys-tems, and a remark-able accurate quartzcrystal time system.So simple a child canoperate, the newCompuCruise com-bines latest computertechnology withstate-of-the-art re-liability in a packagewhich will not likely beavailable on new carsfor years to come •Cruise Control 'Time,E.T., Lap Timer, Alarm

• Time, Distance, Fuelto Arrival • Time, Dis-tance, Fuel to Empty •Time, Distance andFuel on Trip • Currentor Average MPG,GPH»Fuel Used, Dis-tance since FiHup •Current and Aver-age-Vehicle Speed •Inside, Outside orCoolant Temperature

• Battery Voltage •English or MetricDisplay. $199.95

1 HIDSCEIUI Hi'..u'ii-:,ui

L^*

f* tBs^cns

FLOPPY DISKSTORAGE BINDER

This black vinylthree-ring bindercomes with tentransparent plasticsleeves which ac-commodate eithertwenty, five-inch orten, eight-inch floppydisks. The' plasticsleeves may be or-dered separately andadded as needed. Acontents file is in-cluded with eachsleeve for easy iden-tification and organiz-ing, Binder & 10 hol-ders $14.95 Part No.BBOO; Extra holders95* each. Part No.BOD

OPTO-ISOLATED

PARALLEL INPUT

BOARD FOR

APPLE II

There are 8 in-puts that can be dri-ven from TTL logic orany 5 volt source.Thecircuit board can beplugged into any ofthe 8 sockets of yourApple II. It has a 16 pinsocket for standarddip ribbon cable con-nection.

Board only $15.00.Part No. 120, withparts $69.95. PartNp. 120A.

TIDMA

• Tape Interface DirectMemory Access • Re-cord and play programswithout bootstrap load-er (no prom) has FSKencoder/decoder fordirect connections tolow cost recorder at1200 baud rate, anddirect connections forinputs and outputs toa digital recorder atany baud rate »S-100bus compatible • Boardonly $35.00 Part No.112, with parts $110Part No. 112A

SYSTEMMONITOR

80B0, 8085, or Z-BDSystem monitor for usewith the TIDMA board.There is no need for thefront panel. Completewith documentation$12,95.

16K EPROM

Uses 2708 EPROMS,memory speed selec-tion provided, ad-dressable anywhere in65K of memory, canbe shadowed in 4K in-crements. Board only$24.95 part no.7902, with parts lessEPROMs $49.95 partno. 7902A.

ASCII KEYBOARD

TTL & DTL compatible • Full 67 key array

• Full 128 character ASCII output • Positivelogic with outputs resting low • Data Strobe

• Five user-definable spare keys • Standard22 pin dual card edge connector • Requires+5VDC, 325 mA. Assembled S. Tested.Cherry Pro Part No. P70-05AB. $135.00.

ASCII KEYBOARD

53 Keys popular ASR-33 format • RuggedG-10 P. C. Board • Tri-mode MOS encoding• Two-Key Rollover • MOS/DTL/TTL Compat-ible • Upper Case lockout • Data and Strobeinversion option • Three User DefinableKeys • Low contact bounce • Selectable Par-ity • Custom Keycaps • George Risk Model753. Requires +5, -12 volts. $59.95 Kit.

ASCII TO CORRESPONDENCECODE CONVERTER

This bidirectional board is a direct replace-ment for the board inside the Trendata 1000terminal. The on board connector providesRS-232 serial in and out. Sold only as anassembled and tested unit for $229.95.Part No. TA 1000C

DISK JACKET™

Made from heavy duty.0095 matte plasticwith reinforced

grommets. The mini-diskette version holdstwo 5-1/4 inch disk-ettes and will fit anystandard three ringbinder. The pockets tothe left of the disk-ette can be used forlisting the contents ofthe disk. Please orderonly in multitudes often. $9.95/10 Pack.

INTERNATIONAL

MICROPROCESSOR

DICTIONARY

English, French, Dan-ish, German, Italian,Hungarian, Norwe-gian, Polish, Spanish,Swedish. 10 lan-guages, 28 pp.SYBEX. Ref. IMD.$4.95

VIDEO TERMINAL

16 lines, 64 columns •Upper and lower case •5x7 dot matrix •RS-232 in -RS-232out with TTL parallelkeyboard input • Onboard baud rategenerator 75, 110,150, 300. 600, &1200 jumper selecta-ble • Memory 1024characters (7-21L02)• Video processor chipSFF96364 by Necu-lonic • Control char-acters CCR, LF, -., *-,t, f, non destructivecursor, CS, home, CL •White characters onblack background orvice-versa • With theaddition of a keyboard,video monitor or TVset with TV interface(part no. 107A) andpower supply this is acomplete stand aloneterminal 'also S-100compatible • requires+16, S. -16 VDC at100mA, and 8VDC at1A. Part no. 1000A$199.95 kit.

RS-232/20mAINTERFACE

This board has twopassive, opto-isola-ted circuits. One con-verts RS-232 to20mA, the other con-verts 20mA to RS-232. All connectionsgo to a 10 pin edgeconnector. Requires+12 and -12 volts.Board only $9.95,part no. 7901, withparts $14.95 PartNo. 7901A.

COMPUCOLORII

Model 3, 8K $1395.Model 4, 16K$1595.Model 5, 32K $1895.Prices include colormonitor, computer,and one disk drive.

mm g*—*-

PET COMPUTER

With 32K & monitor -$1195. Dual DiskDrive-$1195.

ffccippta

APPLE II PLUS

16K - $995, 32K$1059, 48K -$1123.Disk&cont $589

6502

APPLICATIONS

BOOK

Z80 APPLICATIONS

BOOK*This book will teachyou how to connect aboard to the outsideworld and implementpractical applicationsfor the 6502, (or280). Applicationsrange from home con-trol (a complete alarmsystem, includingheat sensor), to in-dustrial applications.You will learn tech-niques ranging fromsimulated traffic con-trol to analog-digitalconversion. All exper-iments can be realizedwith a minimum of ex-ternal (low-cost!components. They aredirectly applicable toany 6502-basedboard such as SYM,KIM, AIM 65. Thisbook also studies indetail input-outputtechniques and com-ponents, and is theI logical continuation ofC202 tor C2B0). ByRodney Zaks.

SYBEX. 6502: Ref.D302; Z80: RefD380. Each $12.95

T.V. INTERFACE

• Converts video, to,AM modulated RF,Channels 2 or 3. Sopowerful almost notuning is required. Onboard regulated powersupply makes this ex-tremely stable. Ratedvery highly in DoctorDobbs' Journal. Recom-mended by Apple •Power required is 12volts AC C.T., or +5volts DC • Board only$7.60 part No. 107,with parts $13.50 PartNo. 107A

PARALLEL TRIAC

OUTPUT BOARD

FOR APPLE II

This board has B tnacs capable ofswitching 110 volt 6 amp loads (660 wattsper channel) or a total of 5280 watts. Boardonly $15.00 Part No. 210, with parts$119.95 Part No. 21OA.

TX fVfJpr • Mention part no. description, and price. In USA shipping paid by us for orders accompanied by check or money order.' We accept C.O.D. orders in the U. S. only, or a VISA or Master Charge no., expiration date, signature, phone no.,shipping charges will be added. CA residents add 6.5% for tax. Outside USA add 10% for air mail postage and han-dling. Payment must be in U. S. dollars. Dealer inquiries invited. 24 hour order line (408) 226-4064.

Send for FREE Catalog ... a big self-addressed envelope with 41'postage gets it fastest!

ELECTRONIC SYSTEMS DePl- B p- ° Box 21638,SanJose, CAUSA 95151

236 BYTE September 1979

Circle 125 on inquiry card.

TRS-80ESSERIAL I/O

• Can input into basic

• Can use LLIST andLPRINT to output, oroutput continuously •RS-232 compatible •Can be used with orwithout the expansionbus • On board switchselectable baud ratesof 110,150,300,600,1900, 9400, parity orno parity odd or even,5 to 8 data bits, and 1or 2 stop bits. D.T.R.line • Requires +5,-12 VDC • Board only$19.95 Part No. 8010,with parts S59.95 PartNo. 801OA. assembled$79.95 Part No. 8010C. No connectors pro-vided, see below.

EIA/RS-232 con-nector Part NoOB25PS600.«ith9'. 8 conductorcable S1095 PartNo DB25P9

nobon cablewitbattached con-nectors to fit TRS-80 end our serialboard S19.95 PartNo. 3CAB40.

RS-232/ TTLINTERFACE

• Converts TTL to RS-232, and converts RS-232 to TTL* Two sep-arate circuits • Re-quires -12 and +12volts • All connectionsgo to a 10 pin goldplated edge connector

• Board only S4.50Part No. 232, withparts $7.00 Part No.232A 10 Pin edgeconnector $3.00 PartNo. 10P

MODEM

• Type 103 • Full orhalf duplex • Works upto 300 baud • Origi-nate or Answer • Nocoils, only low costcomponents • TTL in-put and output-serial

• Connect 8 fi speak-er and crystal mic.directly to board •Uses XR FSK demod-ulator • Requires +5valts • Board only$7.60 Part No. 109.with parts $27.50 PartNo. 109A

DISKETTES

Box of 10, 5" $29.95,8" $39.95.Plastic box, holds 10diskettes, 5" - $4.50,8"-$6.50.

RS-232/TTYINTERFACE

This board has twoactive circuits, oneconverts RS-232 to20mA, and the otherconverts 20mA toRS-232. Requires+12 and -12 volts.Board only $4.50 PartNo. 600. with parts$7.00 Part No. 600A.

S-100 BUSACTIVE TERMINATOR

Board only $14.95 Part No. 900, with parts$24.95 Part No. 900A

.■::-,V,,'!: ..

APPLE IK-SERIAL I/OINTERFACE

Baud rate is continuously adjustable from 0to 30,000 • Plugs into any peripheralconnector • Low current drain. RS-232 inputand output • On board switch selectable 5 toB data bits, 1 or 2 stop bits, and parity or noparity either odd or even • Jumper selectableaddress • SOFTWARE • Input and Outputroutine from monitor or BASIC to teletype orother serial printer • Program for using anApple II for a video or an intelligent terminal.Also can output in correspondence code tointerface with some selectrics. • Alsowatches DTR • Board only $15.00 Part No.2, with parts $42.00 Part No. 2A, assembled$62.00 Part No. 2C

8K EPROM piiceon

Saves programs on PROM permanentlytuntilerased via UV light] up to 8K bytes. Programsmay be directly run from the program saversuch as fixed routines or assemblers. • S-100 bus compatible • Room for BK bytes ofEPROM non-volatile memory (2708's). • On-board PROM programming • Addressrelocation of each 4K of memory to any 4Kboundary within 64K • Power on jump andreset jump option for "turnkey" systems andcomputers without a front panel • Programsaver software available • Solder mask bothsides • Full silkscreen for easy assembly.Program saver software in 1 2708 EPROM$25. Bare board $35 including custom coil,board with parts but no EPROMS $139, with4 EPROMS $179, with 8 EPROMS $219.

WAMECO PRODUCTS

WITH

ELECTRONIC SYSTEMS PARTS

FDC-1 FLOPPY CONTROLLER BOARD willdrive shugart, pertek, remex 5" SB" drives

up to 8 drives, on board PROM with powerboot up, will operate with CPM (notincluded). PCBD $42.95

FPB-1 Front Panel. (Finally) IMSAI size hexdisplays. Byte or instruction single step.PCBD $42.95

MEM-1A 8KxB fully buffered, S-100, uses2102 type RAMS.PCBD $24.95, $168 Kit

QMB-12 MOTHER BOARD, 13 slot, termi-nated. S-100 board only $34.95

$89.95 Kit

CPU-1 8080A Processor board S-100 with

8 level vector interrupt PCBD .. $25.95

$89.95 Kit

RTC-1 Realtime clock board. Two independ-ent interrupts. Software programmable.PCBD $25.95, $60.95 Kit

EPM-1 1702A4K EPROM

card PCBD $25.95

$49.95 with parts less EPROMS

EPM-2 2708/2716 16K/32K

EPROM card PCBD $24.95

$49.95 with parts less EPROMS

QMB-9 MOTHER BOARD. Short Version of

QMB-1 2. 9 Slots PCBD $30.95

$67.95 Kit

MEM-2 16Kx8 Fully Buffered 2114 BoardPCBD $25.95, $269.95 Kit

T.V.TYPEWRITER

• Stand alone TVT

• 32 char/line, 16lines, modifications for64 char/line included

• Parallel ASCII (TTL)input • Video output

• 1K on board memory

• Output for computercontrolled curser •Auto scroll • Non-destructive curser •Curser inputs: up, down,left, right, home, EOL,EDS • Scroll up, down

• Requires +5 voltsat 1.5 amps, and -12volts at 30 mA • All7400, TTL chips •Char. gen. 2513 •Upper case only •Board only $39.00Part No. 106, withparts $145.00 PartNo. 106A

UART&BAUD RATEGENERATOR

• Converts serial toparallel and parallel toserial • Low cost onboard baud rate gener-ator • Baud rates:110, 150, 300, 600,1200, and 2400 •Low power drain +5volts and -12 voltsrequired • TTL com-patible • All characterscontain a start bit, 5to 8 data bits, 1 or 2stop bits, and eitherodd or even parity. • Allconnections go to a 44pin gold plated edgeconnector • Board only$12.00 Part No. 101,with parts $35.00 PartNo. 101 A, 44 pin edgeconnector $4.00 PartNo. 44P

TAPEINTERFACE

• Play and record Kan-sas City Standard tapes

• Converts a low costtape recorder to adigital recorder • Worksup to 1200 baud* Dig-ital in and DUt are TTL-serial • Output ofboard connects to mic.in of recorder • Ear-phone of recorder con-nects to input on board

• No coils • Requires+5 volts, low powerdrain • Board only$7.60 Part No. 111,with parts $27.50 PartNo. 111A

HEX ENCODEDKEYBOARD

E.S.This HEX keyboardhas 19 keys, 16 encod-ed with 3 user defin-able. The encoded TTLoutputs, 8-4-2-1 andSTROBE are debouncedand available in trueand complement form.Four onboard LEDsindicate the HEX codegenerated for eachkey depression. Theboard requires a single+5 volt supply. Boardonly $15.00 Part No.HEX-3, with parts$49.95 Part No. HEX-3A. 44 pin edge con-nector $4.00 Part No.44P.

DC POWER SUPPLY

• Board supplies a regulated +5volts at 3 amps., +1 2, -12, and -5volts at 1 amp. • Power required is8 volts AC at 3 amps., and 24 voltsAC C.T. at 1.5 amps. • Board only$12.50 Part No. 6085, with partsexcluding transformers $42.50Part No. 60B5A

TO Ofdfir ■ Mention Part no- description, and price. In USA shipping paid by us for orders accompanied by check or money order.1 We accept C.O.D. orders in the U. S. only, or a VISA or Master Charge no., expiration date, signature, phone no.,shipping charges will be added. CA residents add 6.5% for tax. Outside USA add 10% for air mail postage and han-dling. Payment must be in U. S. dollars. Dealer inquiries invited. 24 hour order line (408) 22B-40B4.

Send for FREE Catalog ... a big self-addressed envelope with 41* postage gets it fastest!

ELECTRONIC SYSTEMS DePt- B. p- °- Box 21638,SanJose, CAUSA 95151

Circle 125 on inquiry card.

BYTE September 1979 237

Circle 126 on inquiry card.

The.) VTA-FRANS1000

A completely refurbishedIBM Selectric Terminal withbuilt-in ASCII Interface.

Features:

$1395

300 Baud

14.9 characters per second

printout

Reliable heavy duty Selectric

mechanism

RS-232C Interface

Documentation included

60 day warranty-parts and

labor

High quality Selectric printing

Off-line use as typewriter

Optional tractor feed available

15 inch carriage width

HO WTO ORDERDATA-TRANS 1000

1. We accept Visa, MasterCharge. Make cashiers checks orpersonal check payable to:

DATA-TRANS

2. All orders are shippedF.O.B. San Jose, CA

3. Deliveries are immediate

For orders and information

DATA-TRANS

2154 0TooleSt

UnitE

San Jose, CA 95131

Phone: (408) 263-9246

MICRO-PROCESSORS:FROM CHIPS TOSYSTEMS

This book cover all as-pects of microp-rocessors, from thebasic concepts to ad-vanced interfacingtechniques, in a pro-gressive presenta-tion. It is independentfrom any manufac-turer, and presentsuniform standardprinciples and designtechniques, includingthe interconnect of astandard system, aswell as specific com-ponents. It intro-duces the MPU, howit works internally, thesystem components(ROM, RAM, UART,PIO, others), the sys-tem interconnect,applications. pro-gramming, and theproblems and tech-niques of system de-velopment. By R.Zaks. SYBEX. Ref.C201.S9.95

MICRO-PROCESSORINTERFACINGTECHNIQUES

Microprocessor in-terfacing is no longeran art. It is a set oftechniques, and insome cases Just a setof components. Thiscomprehensive bookintroduces the basicinterfacing conceptsand techniques, thenpresents in detail theimplementation de-tails, from'hardwareto software. It coversall the essential per-ipherals, from key-board to floppy disk,as well as the stan-dard buses (S100 toIEEE 4BB) and intro-duces the basic trou-bleshooting tech-niques. (2nd Ex-panded Edition). ByAustin Lesea and R.Zaks. Ref. C207SYBEX. $11.95

PROGRAMMINGTHE 6502

PROGRAMMINGTHEZBO

PROGRAMMINGTHE 8080'It covers all essentialaspects of program-ming, as well as theadvantages and dis-advantages of the6502 and shouldbring the reader tothe point where hecan start writingcomplete applicationsprograms. For thereader who wishesmore, a companionvolume is available:The 6502 Applica-tions Book. By R.Zaks. 6502: Ref.C202; Z80: Ref.C280; B080: Ref.C208. SYBEX. Each$10.95

44 BUS MOTHERBOARD

Has provisions for tan44 pin (.156) connec-tors, spaced 3/4 of aninch apart. Pin 20 isconnected to X, and22 is connected to Zfor power and ground.All the other pins areconnected in parallel.This board also hasprovisions for bypasscapacitors. Boardcost $15.00 Part No.102. Connectors

$3.00 each Part No.44WP.

AN INTRODUCTION

TO PERSONALAND

BUSINESS

COMPUTING

No computer back-ground is required.The book is designedto educate the readerin all the aspects of asystem, from the se-lection of the mic-rocomputer to therequired peripherals.By Rodnay Zaks. Ref.C200, SYBEX $6.95

TVT COOKBOOK

Bk 1064 — by DonLancaster. Describesthe use of a standardtelevision receiver asa microprocessorCRT terminal: Ex-plains and describescharacter genera-tion, cursor controland interface infor-mation in typical, easy-to- understand Lan-cascaster style$9.95

COMPUTER

PROGRAMMING

HANDBOOK

A complete guide tocomputer programm-ing & data process-ing. Includes manyworked-out examples.By Peter Staak, TAB$9.95

DIGITALCASSETTE

5 min. each side. Boxof 10 $9.95. Part No.C-5.

Tq QrHgf ■ Mention part no. description, and price. In USA shipping paid by us for orders accompanied by check or money order.1 V\fe accept COD. orders in the U. S. only, or a VISA or Master Charge no., expiration date, signature, phone no.,shipping charges will be added. CA residents add 6.5% for tax. Outside USA add 10% for air mail postage and han-dling. Payment must be in U. S. dollars. Dealer inquiries invited. 24 hour order line (408) 226-4064.

Send for FREE Catalog ... a big self-addressed envelope with 41e postage gets it fastest!

ELECTRONIC SYSTEMS °* b.

P. 0. Box 21638, San Jose, CA USA 95151

238 BYTE September 1979

Circle 125 on inquiry card.

PERQOM SAMPLER

a r

tMf 0ti

300 '

j»[F30M <^l

For yourCIS-30+

SS-50 bus computer — the

• Interface to data terminal and hvo cas-sette recorders with a unit only 1/10the size of SWTP's AC-30.

• Select 30, 60, or 120 bytes per secondcassette interfacing, 300, 600 or 1200baud data terminal interfacing.

• Optional mod kits make CIS-30+ workwith any microcomputer. (For MITS680b, ask for Tech Memo TM-CIS-30+—09.)

• KC-Standard/Bi-Phase-M (double fre-quency) cassette data encoding. De-pendable self-clocking operation.

• Ordinary functions may be accom-plished with 6800 Mikbug™ monitor.

• Prices: Kit, $79.95; Assembled,$99.95.

Prices include a comprehensive instructionmanual. Also available: Test Cassette, Re-mote Control Kit (for program control ofrecorders), IC Socket Kit, MITS 680b moddocumentation, Universal Adaptor Kit(converts CIS-30+ tor use with any com-puter). MIKBUG®Motorola, Inc.

In the Product DevelopmentQueue . . .

Coming PDQ. Watch lor announce-ments.

6809 Processor Card — With this SS-50bus PC board, you'll be able to upgradewith the microprocessor that Motoroladesigners describe as the "best 8-bitmachine so far made by humans."The Electric Crayon™ — This colorgraphics system includes its own /nP andinterfaces to virtually any microcomputerwith a parallel I/O port.

Printer Interface — For your TRS-80™.Interface any serial RS232 printer to yourTRS-80™ with this system.

'"ELECTRIC WINDOW. ELECTRIC CRAYON. Pilon-30 and Pilon-10 are trademarks of Percom DataCompany, Inc.

TRS-80 is a trademark of Tandy Corporation and RadioShack which has no relationship to Percom Data Company.

Orders may be paid by check or money order,or charged to Visa or Master Charge creditaccount. Texas residents must add 5% salestai.

For your data storage — Pllon-30™ andPilon-10™ data cassettes

• Orders-of-magnitude improvement indata integrity over ordinary audio cas-settes.

• Pilon-coated pressure pad eliminateslint-producing felt pad of standardaudio cassettes.

• Smooth pilon coating minimizes erra-tic tape motion.

• Foam pad spring is energy absorbing.Superior to leaf spring mounted padwhich tends to oscillate and cause flut-ter.

• Five-screw case design virtually pre-cludes deformation during assembly.

• Price: $2.49.

For your S-100 computer—the CI-812

• Both cassette and data terminal inter-facing on one S-100 bus PC board.

• Interfaces two recorders. Record andplayback circuits are independent.

• Select 30, 60, 120, or 240 bytes persecond cassette interfacing, 110 to9600 baud data terminal interfacing.

• KC-Standard/Bi-Phase-M (double fre-quency) encoded cassette data. De-pendable self-clocking operation.

• Optional firmware (2708 EPROM)Operating System available.

• Prices: kit, $99.95; assembled,$129.95.

Prices include a comprehensive instructionmanual. In addition to the EPROM OperatingSystem, a Test Cassette, Remote Control Kit(for program control of recorders), and an ICSocket Kit are also available.

CASSETTE SOFTWARE

For 8080/Z-80 ju.C«....

BASIC ETC — Developed by the co-authors of the original Tiny BASIC, BASICETC is easy to use yet includes com-mands and functions required for power-ful business and scientific programs aswell as for hobby applications. 9.5K bytesof RAM. 1200-baud cassette and 42-pageuser's manual $35.00

Cassette Operating System — EPROM(2708) COS for the Percom CI-812 dualperipheral interfacing PC card .. $39.95

If you're programming on a 6800 fiC,you'll want these development and de-bugging programs written by Ed Smith ofthe Software Works:

Disassembler/Source Generator — Dis-assembles SWTP Resident Assembler,TSC Mnemonic Assembler/Text Editor orSmoke Signal Mnemonic Assembler/TextEditor and produces compacted sourcecode suitable for re-editing. Prints or dis-plays full assembly-type output listing.4K bytes of RAM.(Order M68SG) $25.00

Disassembler/Trace — Use to examine(or examine and execute) any area ofRAM or ROM. "Software-single-step"through any program, change the con-tents of CPU or memory location at anytime, trace subroutines to any depth.2.3K bytes of RAM.

(Order M68DT) $20.00

EPROM Support/Relocator Program —This program relocates a program in anycontiguous area of RAM or ROM to any-where in RAM. Use to assemble and testprograms in RAM, adjust programs forEPROM operating addresses and thenblock move to your EPROM burner ad-dress. 952 bytes of RAM. Loads at hex1000.

(Order M68EP) $20.00

Relocating Assembler & Linking Loader(M68AS) $50.00

Relocating Disassembler & SegmentedSource Teit Generator (M68RS) $35.00

Americana Plus — 14 tunes for the New-tech Model 68 Music Board in machinelanguage ready to load and run. Cassettecompatible with Percom CIS-30+ andSWTP AC-30. Order MC-1SW .. $15.95

HARDWARE

Newtech Model 68 Music Board — Pro-duces melodies, rhythms, sound effects,morse code, etc. from your programs.Includes manual with BASIC for writingmusic scores and assembly languageroutine to play them. Installs in SWTP I/Oslot. Assembled & tested $59.95

The Percom ELECTRIC WINDOW™ —

Memory-resident and programmable,this video display character generatorboard for your SS-50 bus displays up to24 80-character lines. Features dualcharacter generators, dual-intensityhigh-lighting. One programmable regis-ter controls scrolling. Compatible with

standard video monitors $249.95

SS-50 Prototype Cards:

Large card (up to 70 40-pin ICs) $24.95

I/O size card $14.95

PERCOM™ 'peripherals for personal computing'

PERCOM DATA COMPANY, INC.

DEPT. B

211N.KIRBY* GARLAND, TX. 75042

To order products or request additional lit-erature, call Percom's toll-free number:1-800-527-1592. For detail technical In-formation call (214) 272-3421.

Circle 306 on inquiry card.

BYTE September 1979 239

P.O. Box 4430X Santa Clara, CA 95054

ATTENTION ELF OWNERSANNOUNCING QUEST SUPER BASIC

At last a Full Size Basic for 1802 systems. Acomplete function Basic Including two dimen-sional arrays, string variables, floating point,arithmetic and 32 bit signed integer arithmetic(10 digit accuracy) with I/O routines. Easily adap-table on most 1802 systems. Requires 12K RAMminimum for Basic and user programs. Cassetteversion in stock now for Immediate delivery.ROM versions coming soon with exchangeprivilege allowing credit for cassette version.Super Basic on Cassette $40.00

Tiny Basic Source now available $19.00

S-100 Slot Expansion. Add 3 more S-100 slots toyour Super Expansion Board or use as a 4 slotS-100 Mother Board. Board without connectors$9.95.

Coming Soon: High resolution alpha/numericswith color graphics expandable up to 256 x 192resolution for less than $100. Economical ver-sions for other popular 1802 systems also.16K Dynamic RAM board expandable to 32K forless than $150.

RCA Cosmac Super Elf Computer $106.95

Compare features before you decide to buy anyother computer. There is no other computer onthe market today that has all the desirable bene-fits of the Super Elf for so little money. The SuperElf is a small single board computer that doesmany big things. It Is an excellent computer fortraining and for learning programming with itsmachine language and yet it is easily expandedwith additional memory, Full Basic, ASCIIKeyboards, video character generation, etc.Before you buy another small computer, see if itincludes the following features: ROM monitor:State and Mode displays; Single step: Optionaladdress displays: Power Supply; Audio Amplifierand Speaker; Fully socketed for all IC's; Real costof in warranty repairs; Full documentation.The Super Elf includes a ROM monitor for pro-gram loading, editing and execution with SINGLESTEP for program debugging which is not In-cluded in others at the same price. With SINGLESTEP you can see the microprocessor chip opera-ting with the unique Quest address and data busdisplays belore, during and after executing in-structions. Also, CPU mode and instruction cycleare decoded and displayed on 8 LED indicators.An RCA 1861 video graphics chip allows you toconnect to your own TV with an Inexpensive videomodulator to do graphics and games. There Is aspeaker system included for writing your ownmusic or using many music programs alreadywritten. The speaker amplifier may also be usedto drive relays for control purposes.

A 24 key HEX keyboard Includes 16 HEX keysplus load, mat, run, wait, Input, memory pro-tact, monitor select and single step. Large, onboard displays provide output and optional highand low address. There is a 44 pin standardconnector slot for PC cards and a 50 pin connec-tor slot for the Quest Super Expansion Board.Power supply and sockets for all IC's are in-cluded in the price plus a detailed 127 pg. instruc-tion manual which now includes over 40 pgs. ofsoftware info. Including a series of lessons tohelp get you started and a music program andgraphics target game.

Many schools and universities are using theSuper Elf as a course of study. OEM's use It fortraining and research and development.Remember, other computers only offer Super Elffeatures at additional cost or not at all. Comparebelore you buy. Super Elf Kit $105.95, Highaddress option $8.95, Low address option$9.95. Custom Cabinet with drilled and labelledplexiglass front panel $24.95. Expansion Cabinetwith room for 4 S-100 boards $41.00. NICedBattery Memory Saver Kit $5.95. All kits andoptions also come completely assembled andtested.

Questdata, a 12 page monthly software publica-tion for 1802 computer users Is available by sub-scription for $12.00 per year.Tiny Basic Cassette $10.00, on ROM $38.00,original Elf kit board $14.95.

Super Expansion Board with Cassette Interface $89.95

This is truly an astounding valuel This board hasbeen designed to allow you to decide how youwant it optioned. The Super Expansion Boardcomes with 4K of low power RAM fully address-able anywhere In 64K with built-in memory pro-tect and a cassette Interlace. Provisions havebeen made for all other options on the sameboard and it fits neatly into the hardwood cabinetalongside the Super Ell. The board includes slotsfor up to 6K of EPROM (2708, 2758, 2716 or Tl2716) and is fully socketed. EPROM can be usedtor the monitor and Tiny Basic or other purposes.A K Super ROM Monitor $19.95 is available asan on board option in 2708 EPROM which hasbeen preprogrammed with a program loader/editor and error checking multi file cassetteread/write software, (relocatible cassette file)another exclusive from Quest. It Includes registersave and readout, block move capability andvideo graphics driver with blinking cursor. Breakpoints can be used with the register save featureto isolate program bugs quickly, then follow withsingle step. The Super Monitor is written withsubroutines allowing users to take advantage of

monitor functions simply by calling them up.Improvements and revisions are easily done withthe monitor. If you have the Super ExpansionBoard and Super Monitor the monitor is up andrunning at the push of a button.Other on board options Include Parallel Inputand Output Ports with lull handshake. Theyallow easy connection of an ASCII keyboard to theinput port. RS 232 and 20 ma Current Loop forteletype or other device are on board and if youneed more memory there are two S-100 slots forstatic RAM or video boards. A Godbout 8K RAMboard is available for $135.00. Also a 1K SuperMonitor version 2 with video driver for full capa-bility display with Tiny Basic and a video Interfaceboard. Parallel I/O Ports $9.85, RS 232 $4.50,TTY 20 ma l/F $1.95, S-100 $4.50. A 50 pinconnector sat with ribbon cable Is available at$12.50 for easy connection between the SuperEll and the Super Expansion Board.The Power Supply Kit for the Super ExpansionBoard is a 5 amp supply with multiple positive andnegative voltages $29.95. Add $4.00 for shipping.Prepunched frame$7.50. Case $10.00. Add $1.50for shipping.

Multi-volt Computer Power Supply

8v 5 amp, ±18v .5 amp, 5v 1.5 amp, -5v.5 amp, 12v .5 amp, -12 option. ±5v, ±12vare regulated. Kit $29.95. Kit with punched frame$37.45. Woodgrain case $10.00.

60 Hz Crystal Time Base Kit $4.40

Converts digital clocks from AC line frequencyto crystal time base. Outstanding accuracy. Kitincludes: PC board, IC, crystal, resistors, ca-pacitors and trimmer.

TERMS: SD.00 mm. order U.S. Funds. Calif residents add 6% tax.BankAmencard and Master Charge accepted.Shipping charges will be added on charge cards.

Same day shipmont. First line parts only.Factory tested. Guaranteed money back.Quality IC's and other components at fac-tory prices.

INTEGRATED CIRCUITS

7IWTTI

740QN

740IN

7«4N

7409M

7410N

7414N

74ZON

7422N

7430N

7442N

7445N

7447M

744BN

7450N

7474N

7475N

7485N

7489N

7490N

7492N

7493N

7495N

741DON

74107N

74121N

74123N

7412 SN

74 MSN

74150H

74I51N

74154N

74157N

74161N

7416ZN

74163N

74174N

74175N

74I90N

74192H

74193N

74221N

7429BN

74365N

743GSN

74367N

.86

74LSWTTL

74LS00N .25

74LS02H .25

74LS04K .25

74LS05H .25

74LS06N 25

74LS10N .25

74LSI3N 40

74LS14N 90

74LS20N .25

74L522N .25

7JI.S2BM .41

74LS30N .25

74LS33N .39

741S3BN .30

74LS74N .70

74LS75N .47

74L59QN .51

74LSS3N 51

74LS95N 169

74LS107N 35

74LS112N .35

74LS113N .35

74LS13ZN .72

74LS136N .35

74LS151N .67

74LSI55N .67

74LS157N .67

74LS162N Jt

74LS163N .91

74LS174H .95

74LS190N 1.06

74LS221N 1.95

74LS25BN -87

MLS367N 1,35

UttEAR

CA3045 .90

CA3046 67

CA3061 1.80

CA3082 1 90

CA30BB 2.95LM301

AN/AK .35

LM305H .87

LM307N .35

LM308N B9

LM309H 115

LM309K 1-50

LM311H/N 90

LM317T/K

?m

LM31B

1M

LM320K-5

1?n

a,m

LM320K-12

w\

LM320K-15

1.15

LM320T-S

1 (Ml

LM320TB

i n

LH320T-12

IM

LM320T-1S

i no

LM324N

1,15

LM339H

1,55

LM340K-5

1.35

LM340K-B

1 35

CM340K-12

138

LM340K-15

135

LM340K-24

1.35

LM340T-5

1,W

LM340T-B

1 ?ft

LM340T-12

175

LM340T-15

175

LM340T-1£

i n

LM340T-2J

125

LM343H

450

LM350

750

LM370

1.15

LM377

:iiio

LM379

100

LM3S0N

1.00

IM3SI

i m

LM382

t no

LM703H

40

LM709H

78

LM723H/N

SO

LM733N

87

LM741CM

Vt

LM741N

75

LM747H/N

.87

LM746N

.35

LM1303N

.82

LM1304

1,10

LM1305

17/

LM1307

■I (ill

L.M1310

7 7fi

LM145B

47

LM1800

1 75

LM1S12

750

LM1889

3 00

LM2111

1.75

LM29C2

150

LM39O0N

Ml

1 75

LM3909N

81

MC1458V

50

NES40L

?m

NE5SON

.65

NE555V

4.1

NE556A

.79

NE5GSA

1.00

NE5B6V

inn

NE567V

1,70

NE570B

5 00

HE571B

soo

7BL05

(Ml

7BL08

80

78M05

85

75108

175

75491CN

SO

55

75494CN

.89

Ala U

CONVERTER

803BB

4fi0

B700CJ

13 95

8701CN

V mi

875QCJ

L013Q

'I'lS

8400CJV/I

7 40

ICL7103

g u

ICL7107

14.25

F*K.CD4O00CD4O01C04002CD4006CD40Q7CO 4001)CD4O09CD4O10CD4011C040I7CD4013CD4014

CD4015

CD401E

CD4017

CD401B

CD40I9

CO4020

C04021

CD4022

CD4DZ3

CD4074

CO4025

CD4026

CD4027

C0402B

CD40Z9

C04030

CO4035

C04040

CD4042

C04043

CD4044

CD4046

CD4049

C040S0

CD4D51

CD40S0

CO 4056

CD406B

C04069

C04070

CO4071

CO4072

CO 4073

C04075

CD4076

CD4076

CD4081

CD4082

CD4116

CD4490

CO4507

C0450B

CD4510

CD4511

C04515

CD4516

C04518

C04520

CD4527

CD4528

CD4S53

CD4566

CD4583

CD45B5

CD40192

74C00

74C04

74C10

74C14

74C2Q

74C30

74C48

74C74

74C76

74C90

74C93

74C154

74C160

740175

74C192

74C221

74C905

74C90G

74C914

74C922

74C923

74C925

74C926

74C927

8T205T238T24BT258T268T28BT97BT9B

RAM

2101-12102-1

2102AL-421L02-121F02

2104A-42107B-42111-12112-22114L-3

inns

2513B

R30

MM5262

40

MM52BO

300

MM5320

9 05

MM5330

SM

PD411D-3

400

PD411D-4

5 00

P5101L

1395

4200A

9 95

82S25

2.00

91L02A

1.50

HD0165-5

695

MM57100

4R0

G1AY38500-

n»(>

MCM657IA

9 95

936B

3.50

NB2SI36 8.75

NB2S137 B75

270B 10.50

DM8577 2.90

8223 2.90

2716T1 29.50

271B Intel 48.00

CONNECTORS

44 pin edge 2.75100 pin edge 4.50100 pin edge. WW 5.25

IC SOCKETS

Bolder Tin Low ProfilePIN 1UP PIN 1UP

18 77 36 .58

RESISTORS V. wot 5\10 per type 03 1000 per rype 01:25 per type 025 350 piece peck

100 per type .015 5 per type 6.7!

KEYBOARDS

56 key ASCII keyboard *til

167.50

Fully assembled 77.50

53 key ASCII keyboard kR 60 00

Fully assembled 70.00 Enclosure 14 95

uos

Red T018 .15

Green. Yellow T016 .20

Jumbo Red 20

Gieen. Orange. Yellow Jumt» 25Cllplfle LED Mounting Clips 87*175(specifyred. amber, green, yellow, deai)

CONTINENTAL SPECIALTIES In HockComplete line ol breadboard lesi equip

20 79 40 .57 MAM DO 8 dlgH Frtq. Or.

1445

CLOCKS

MU5314

MM5315

MM5369

MM5B41

MM5885

CnOOl 5.80

CT7010 8.95

CT7015 7.25

HW5375AA/N 3.90

MM5375AG/N 4.90

7205 16.50

7207

720B

7209 4.»

OS0026CN 3 75

050056CN 3.75

MH53104 250

MICnOFKOCESSOR68O0 1750

6802 18.75

15.95

B0B5ZBOA821282148218B22482288251B253B2558257

ptae.

13.91

tB02DP

plis. 17.95

1B61P 11.50

COP1802CD 19.95

COP1602D 25"CDP1861

68206850650765046522

UART.'FIFOAY5-1013AY5-10143341

PflOM1702A

N82S23NS2S123N82S126N82S129N82S131

12.9S

9.9512.9512.5016 50

13.60

WIRE WRAP LEVEL 3

16 .33 28 10018 57 40 1 23

5MHi

10 MM.'18 MHz

20MH132 MM32768 MHi

1 B432MH23.5795 MHz2.01DOMH1

2 097152 MHi2.4576 Mm3.276B MHi5.0688 MKi

5 165 MHz5.7143 MHz6.5536 MHi14.31818 MHi18.432 MHz22.11B4MHi

KEYBOARD ENCODERSAY57376 $12.50

AY5-3600 17.95

74C922 5.50

74C923 5 50

HD0165-5 6.95

D Connecton RS232

D325P 2.95

DB25S 3.95

Cover 1.50RS232 Complete Set 6.50

DE9S 1.95

0A15P 2.10

DA15S 3 10

TRANSISTORS

2H1893 40

2N2222A IB

2N2369 30

2N2904A 70

2N2907A .25

2N3053 .40

2H363B 25

2N3643 75

2N3904 .IS

2N3906 IS

2N3055 69

2N4400 75

2N4401 .75

2N4402 .20TIP31TIP33A

SPECIAL PRODUCTSMM586S Stopwatch Timer 9 00PC board 7 50

Swttchel Mom Pushbutton 273 pos lade .25

Encoder HDQ165S 6.95

3 Dlitl Univ.nilCounter Board KitOperates 5-1B Voll DC lo 5 MHityp- 125'LED display 10.80

Pintronlti 1D0A LogicAntlyiar Kit 1224.00

Model 10 Triggei

if KB

1229.00

Model 150 Bus

Grabber KK $369.00

Sinciilr Jli Olgri

MiKJmeler III 15

Clort Calendar Ktl 123.K

2.5 MHz FreqoencT Countir

Kll 137.50

30 MHr Friquency CountetKll (47.76

TRANSFORMERS

6V 300 ma 3.2512 Volt 300 m* IranilOf m« 175

12 6VCT600m» 3.75

12V 250 ma wan plug 2.95

12V CT 250 ma wan plug 3.50

24V CT 400 ma 3 95

10V 17 amp will plug 4 65

12V 6 amp 12 95

DISPLAY L£DS

MAN1 CA 270 2

MANS CC 125

MAN72/74 CA/CA 300 1

OL704 CC 300 1

0L7D7(TJL707R CA 300 1

0L727/728 CA/CC .500 1

CA7CC 600 1

CC BOO 1

CC 357

cacA 5001

CC/CA 500

CC/CA BOO 2

DL747/750

DL750

FND359

FNO50O/5O7

FND503/510

FNO8O0/8O7

3 ciiji: BuDOle

4 digit Bubble0G8 FluorescentDG10 Fluorescent

5 digit 14 pin displayNSN69 9 digit display7520 Claires photocellsTIL311 Hex

MA1001A 8.95

MA1012A 8.98

102P3 Iranerormer 27S

Additional Drive Krt

iy Din Kll S665 00

Rockwell AIM 65 Computer

6502 based single board with full ASCII keyboardand 20 column thermal printer. 20 char, al-phanumeric display, ROM monitor, fully expand-able. $375.00. 4K version $450.00. 4K Assem-bler $85.00, 8K Basic Interpreter $100.00.Power supply assy, in case $60.00. AIM 65 inthin briefcase with power supply $485.00.

Not a Cheap Clock Kit $14.95

Includes everything except case. 2-PC boards.6-.50" LED Displays. 5314 clock chip, trans-former, all components and full Instructions.Orange displays also avail. Same kit w/.80"displays. Red only. $21.95 Case $11.75

Video Modular Kit $8.95

Convert your TV set into a high quality monitorwithout affecting normal usage. Complete kitwith full instructions.

S-100 Computer Boards

8K Static RAM Kit Godbout $135.00

16K Static RAM Kit 265.00

24K Static RAM Kit 423.00

32K Dynamic RAM Kit 310.00

64K Dynamic RAM Kit 470.00

8K/16K Eprom Kit (less PROMS) $89.00

Video Interface Kit $139.00Motherboard $39. Extender Board $8.99

79 IC Update Master Manual $35.00

Complete IC data selector, 2500 pg. master refer-ence guide. Over 50,000 cross references. Freeupdate service through 1979. Domestic postage$3.50.1978 IC Master closeout $19.50. No foreignorders.

Auto Clock Kit $17.95

DC clock with 4-.50" displays. Uses NationalMA-1012 module with alarm option. Includeslight dimmer, crystal timebase PC boards. Fullyregulated, comp. instructs. Add $3.95 for beau-tiful dark gray case. Best value anywhere.

Stopwatch Kit $26.95

Full six digit battery operated. 2-5 volts.3.2768 MHz crystal accuracy. Times to 59min., 59 sec., 99 1/100 sec. Times std., splitand Taylor. 7205 chip, all components minuscase. Full Instructions.

NiCad Battery Fixer/Charger Kit

Opens shorted cells that won't hold a chargeand then charges them up, all in one kit w/fullparts and instructions. $7.25

PROM Eraser

Will erase 25 PROMs in 15 minutes. Ultra-violet, assembled $34.50

Hickok 3Vz Digit LCD Multimeter

Batt/AC oper. 0.1mv-1000v. 5 ranges. 0.5%accur. Resistance 6 low power ranges 0.1ohm-20M ohm. DC curr. .01 to 100ma. Handheld, W LCD displays, auto zero, polarity, over-range. $69.95.

Digital Temp. Meter Kit $39.95

Indoor and outdoor. Switches back and forth.Beautiful. 50" LED readouts. Nothing like itavailable, Needs no additional parts for com-plete, full operation. Will measure -100° to+ 200°F, tenths of a degree, air or liquid.Beautiful woodgrain case w/bezel $11.75

FREE: Send lor your copy ol our NEW 1979QUEST CATALOG. Include 28c stamp.

240 BYTE September 1979

Circle 311 on inquiry card.

The EXPANDORAM is availablein versions from 16K up to 64K, sofor a minimum investment youcan have a memory system thatwill grow with your needs. This isa dynamic memory with the in-visable on-board refresh, and ITWORKS!

• Interfaces with Altair, IMSAI, SOL-8,Cromenco, SBC-100, and others.

• Bank Selectable

• Phantom

• Power 8VDC, ± 16VDC, 5 Watts

• Lowest Cost Per Bit

• Uses Popular 4116 RAMS

• PC Board is doubled solder masked andhas silk-screen parts layout.

our new retail loca

SD EXPANDORAM

1U ttiUmatt, S-fOO THentMy

Circle 312 or

Extensive documentation clear-ly written

Complete Kit includes allSockets for 64KMemory access time: 375ns,Cycle time: 500ns.No wait states required.16K boundries and Protectionvia Dip SwitchesDesigned to work with Z-80,8080, 8085 CPU's.

)ISC DRIVES

EXPAND0 64KIT(4116)

16K $249

32K $324

48K $399

64K $474

SHUGART SA 400 5'/."

110 KB. 35 tracks,SHUGART SA 400 $295.00

SHUGART SA 400

Willi attractive metal case with

cutouts lor Data Cable switch.

luse and power cord

LOBO SA400-C $325.00

SHUGART SA400

with Cabinet and Power Supply.

Assembled, tested & guaranteed

LOBO SA400-PSC $395.00

SHUGART 801R 8"

6 4 megabits, single or double

density, hard Or soft sector, writB

protect, and more

SHUGART 801R $449.00

Siemens FDD 200-3 8"double-sided double density

$650.00

DISC CONTROLLERSD "VERSAFLOPPY" Kit

The Versatile Floppy Disk Hnlu '1 <^QController Y'"* 'OT

FEATURES: IBM 3740 Soft Sectored Compati-ble. S-100 BUS Compatible for Z-80 or 8080. Con-trols up to 4 Drives {single or double sided).Directly controls the following drives:

1. Shugart SA400/450 Mini Floppy

2. Shugart SA800/850 Standard Floppy.

3. PERSCI 70 and 277.

4. MFE 700/750.

5. CDC 9404/9406.

6. GSI/Siemans FDD120-8.

34 Pin Connector for Mini Floppy. 50 Pin Connector tor Standard Floppy. Operates withmodified CP/M operating system and C-BasicCompiler. The new "Versafloppy" from S.D.Computer Products provides complete controlfor many of the available Floppy Disk Drives.Both Mini and Full Size. FD1771B-1 Single Den-sity Controller Chip. Listings for Control Soft-ware are Included In price. „ . /«/*nn

LCPM for SD Versafloppy & 100

lr

DUAL SHUGARDISC DRIVES

with"DOWf

New from Lobo Drives, a dual Cabinet complete with"power supply;and Shugart 801R disc drives.

• Cabinet accepts 2 801R drives mounted side by side horizontally.

• Power Supply for 2 drives

• Ad-on drives available

• Assembled, tested and guaranteed by Lobo Drives.

• Single or double density • Hard or soft sector • Write Protect

• Capacity: Unformatted single density 3.2 megabitsdouble density 6.4 i

BM format, 2 megabits500 KBS transfer, 77 tracks.

• Shugart 800 Series Compatible

LOBO 801R-1 Pes. Dual Cabinet with 1 drive ....J. $599.00

LOBO 801R-2 Pes. Dual Cabinet with 2 drives $1025.00

SHUGART 801R Ad-on disc drive $449.00

• bingk»Cap

on rV500

ector • Write Protimegabits imegabits,^^L

.Z\f. $59!

rCQNriNfNTAL SPECIALTIES CORPORATION

LOGIC PROBES

Logic Probes andDigital Pulsers

*«* "^ ^

CSC logic probes are (he ultimate tool for breadboard design and testing.These hand held units provide an Instant overview of circuit conditions.Simple lo use; just clip power leads to circuit's power supply, set logicfamily switch lo TTUDTL or CMOS/HTL. Touch probB to test node. Tracelogic levels and pulses through digital circuits. Even stretch and latch foreasy pulse detection. Instanl recognition of high, low or Invalid levels, opencircuits and nodes. Simple, dual-level detector LEDs tell It quickly, correct-ly. HI (Logic "1"): LO (Logic "0"). Also Incorporates blinking pulse detector,e.g.. HI and LO LED3 blink on or off. tracking "1" or "0" states at squarewave Irequencles up to 1.5 MHz. Pulse LED blinks on for V, second duringpulse transition. Choice of three models to meet individual requirements;budget, project and speed ol logic circuits.MODEL LP-1

Hand-held logic probe provides instant reading of logic levels for TTL, DTL.HTL or CMOS. Input Impadanca: 100,000 ohms. Minimum Detectable Pulie:50 ns. Maximum Input Signal (Frequency): 10 MHz Pulaa Detector (LED):High speed train or single event. Pulse Memory: Pulse or level transitiondetected and stored. -^ —

kCSC Modal LP-1 Logic Probe-Net Each -M*9$ $42.70

MODEL LP-2

Economy version of Model LP-1. Safer than a vollmeter. More accurate lhana scope. Input Impedance: 300,000 ohms. Minimum Detectable Pulee: 300ns. Maximum Input Signal (Frequency): 1.5 MHz. Pulee Detector (LED): Highspeed train or single event. Pulaa Memory: None. _^ -

CSC Model LP-2 Logic Probe—Nel Each 04rf3f $23.70

MODEL LP-3

High speed logic probe. Captures pulses as short as 10 tw> Input Im-pedance: 500,000 ohms. Minimum Detectable Pulee: 10 ns. Maximum InputSignal (Frequency): 50 MHz. Pulaa Detector (LED): High speed train orsingle event. Pulae Memory: Pulse or level transition detected and stored.CSC Model LP-3 Logic Probe-Net Each 3fotfc$5 $66.45

DIGITAL PULSER

The ultimate In speed and ease of operation. Simply connect clip leads to.Itlve and negative power, then touch OP-1's probe to a circuit node;automatic polarity sensor detects circuit's high or low condition, Depressthe pushbutton and trigger an opposite polarity pulse into the circuit. Fasttroubleshooting includes injecting signals at key points in TTL, DTL, CMOSor other popular circuits. Test with single pulse or 100 pulses per secondvia built-in dual control push-button; button selects single shol or con-tinuous modes. LED indicator monitors operating modes by flashing oncefor single pulse or continuously tor a pulse train. Completely automatic,pencil-size lab/field pulse generator for any family of digital circuits. Out-put: Tri-state. Polarity: Pulse-sensing auto-polarity. Sync and Source: 100mA. Pulae Train; 100 pps. LED Indicator: Flashes for single pulse; stays litfor pulse train.CSC Model DPI Digital Pulaer-Nel Each £743$5 $71.20

SD COMPUTER BOARDS

$319 KIT*VDB-8024 Video Display BoardWith On-Board Z80 Microprocessor

• ['nil HIM 'hnmelcr* by U4 llnodlsjiluy

• Ctarectcre dttplnycd by Iflflfi Revolu-tion 7x10 Matrix

» Kcyhiiurd Timer iuut Interface

• ComptaHtc Video Output

• Separate TTL Level SpM*ronb»Uonurn! Vldin (hsipulf.

• 2K BytCH Independent (hi BoardMemory

• Ow-DoanJZttOMlcropnwcwtof

• ClU'lii-WDlHoluY

• 'M I 'jijiL-r tun) LowerCaacCharactcru

• lYl Special ChanictcrSci

• \SH Additional »*er ProgrammableChafactcm

• Full Cursor Control

• Forward und Reverse ScrollingCapability

• OjierutcsuHun Independent Term Inn!

• Vurlnble Speed Display Rale

• Blinking, Underlining, Field Reverse.Field I'niieci mid (lomtiinuUiinM

$239 KIT' —-n-wSBC-100 Single Board Computerwith Onboard RAM, PROM, CTC

• Four Channel (.ountcr.'Tlnier(ZaO-CTC)

• Software Prof) rain in utile HandGenerator

• S-IOO Bus Compatible

■ No From Panel Required (orOpe

■ OpUnnid Vectored Iniemipt*

• ZSOCcntnd ProccAaWg t'nit

• l<K14ltytcs<il"Kuml<mi Access

• HK Bytes of Available PR< >M

• Serial Input/Outum fun «

$249

Z80 Starter Kit

A Complete Microcomputer on a Board I

Synchro

Oiieruilori

• I'iimiMi'I I■.|...

Asv.H

PRIORITY ONE ELECTRONICS

16723B Roscoe Blvd. Sepulvedo, CA 91343

Terms: Visa, MC, BAC, Check, Money Order, C.O.D. U.S. Funds Only. CA residents add 6% sales lax.Minimum order $10.00, Prepaid U.S. orders less lhan $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 Sept. 1979. OEM and Institutional

Dhone orders welcome (213) 894-8171. (800) 423-5633 inquiries invited.

'/.HO ('crural Processing I

■ III Kith

IBB

• Twolli.dlreeUi.nulH-lili IfUltatHt?

Instruction*

WO)

< )n Ikitinl Keyboard uml Display

• SwiicliSelcciulilel'kDMiirM

Kuiisns Cliv Stundurd Cum

write

Kesian

Interlace

• ^K line KIH'ti Minilitir In RUM

I'ROM I'ni^runinierlliilll

ni-hnurd

.Meinunli.MimlnctiiKlCllanKe

lixpuiisiiin provtslatl lor 01

iS-HX)

■ fttrtu^iitneonilCliunge

C otoieetors

• ZHdCI'lRcKlt.terl'.-mniiiicmi.lCliiu

Wire \Vru|i nreu liircnstini

el mil in,

• I piitnEViigrmiiMiuliH-Hrcukpiitiiih

SliiHlcfiV.ilil>iH.niitiniwl

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• Klngte'Siep Ihniugh RAM m PROM

programming

• Andiiit UHHCtle Ijiudiind lhiui|i

IK Bytes nf RAM (lwqnu

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• Vectored Imemipi* imwtdetl hv

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• Itlcull'iirl^K-rluicntuliiiluiKl

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ORDER TOLL FREE 1-800-423-5633 ORDER TOLL FREE 1-800-423-5633

Visit our new retai

TRS-80 DISCDRIVE

$395

V

Shugart SA400, housed in an attractive metal case,complete with power supply and termination net-work. All you need to do is connect the drives to yourexpansion interface.

1410 $835°° * Separate integral 12-Key Numeric Paditiw www . All 128 ASCII Codes

• 64 Oisplayable Characters

• 24x80 Screen Configuration^^^"^TC^T * H'9n Resolution using a 5x7 Dot Matrix■»—™"mSm • TTY-Style Keyboard Layout

• Cursor Addressing and Sensing

• EIA Interlace

• Eight Selectable Transmission Rates upto 9600 BaudMicroprocessor Based

• Remote Commands

• Attractive Styling for Contemporary En-vironments

Hazeltlne 1400same as 1410 less numeric pad

'7351"1

HaKftnetttt

1500 Reg. $=r*25 s109800 -ah i28Asoiicodes

• 94 Displayable Characters IncludingLower Case

• 24x80 Screen Configuration

• High-Resolution Characters Using a7x10 Dot Matrix

1 ANSI Standard Keyboard Layout in-cluding Numeric Pad

1 Cursor Addressing and Sensing

1 Dual Intensity

► EIA and 20MA Interfacei • Nine Selectable Transmission Rates Upto 19.2 KB

• Auxiliary EIA Output

• Remote Editing Commands

• Standard or Reverse Video!*• Microprocessor Based

HazettW600

ALL THE FEATURES OF THE"1500" PLUS ...

• Cursor Control Keys

• Protected/Unprotected Data

> Transmit Page, Line or Batches of Infor-mation

■ Function Keys—up to 127»Tab/Back Tab/Auto Tab

• Format Mode with Insert and DeleteLine Keys

> 31 Remote Commands including "Ter-minal Status"

J 510 Reg.j5J8t£s1175

ALL THE FEATURES OF THE"1510" PLUS...

Separate Microprocessor-Controlled Printer In-terface which allows:

• Interfacing of both serial and parallel printers

• Printer speed Independent of communicationsbaud rate

• Printer control codes to be sent by the CPUand received by the printer without restrictionor alteration of the terminal (especially usefulfor wide carriage applications)

' Information to be transmitted directly to eitherthe printer or the terminal, or to both

• Operating Modes/Remote Commands;Remote/Local Print; Printer On-Llne

^with/without Display; Printer Off-Une

1520

Reg. $t660T

s149500

PRICE DOES NOT INCLUDE SHIPPING

• Use with TRS-80

• Parallel interface

• Continuous variable printing density80-132 characters per line

• 5x7 dot matrix

• Prints on plain paper, sheets,rolls, fan fold

• Form thickness control

• Horizontal and verticalform positioning .-"'

CENTRONICS 779 PRINTERS

Portable Miniscopes foriElectronic Professionals on

the Go!!! The StandoutOscilloscope development of the Idecade!!! Now -30MHz, dual trace]model. Compare the performance,then compare the price.

1<t sale Probes 1$ with purchase of scope

• 30-Megahertz bandwidth • Accuracy 3% full scale. • Internal, line or external trigger. • Bat-teries and charger/transformer unit included • Graticule: 4x5 divisions, each division 0.25" •Time base: 1 micro sec. to 0.5 sec/div 21 settings • Vertlcle Gain: 0.01 to 50 Volts/dlv. 12 set-tings • Size 2.9"H x 6.4"W x 8.5"D. 3.5 lbs. • TEST MOST DIGITAL LOGIC CIRCUITS IN-CLUDING MICROPROCESSORS •.

41 -141 Deluxe lOtol probe with 4 interchangeable tips $27.00

41 -37 Deluxe 10tol/1tol probe with 4 Interchangeable tips $38.50

41 -180 leather carrying case $45.00

MS-15 Single trace 15 MHz $318.00

MS-215 Dual trace 15 MHz $435.00

3M Scotch® BrandDISKETTES

Part #

Sides/Density

Sectoring

8"

Soft-IBMSoft-IBM32-Shugart 80132-Shugart 801Soft-Shugart Dbl

5"

Soft-Shugart SA400(TRS-80)Soft/10 SA400Soft/16 Micropolis

PriceBox of 10

740-OP

740/2-OP

740-32P

740/2-32P

741-0

1/single2/single1/single2/single1 /double

$39.95$75.00$39.95$75.00$59.00

744-OK

744-10K744-16K

1/single

1/single1/single

$51.00*

$51.00*$51.00*

'Price includes Kas-ette/10 Storage Box a $5.00 Value

■'DON'T SETTLE FOR ANYTHING LESS THAN SCOTCH"

C MODEM

^■^^^

ACOUST

NOVATION CAT

ijytS

• 0-300 Baud

• Bell 103

• Answer, Originate

Reg. $198.00

Sale $189.00

NTIWN1AL SPtCtALllES

75TOUT

779-1 pinch roll

friction feed

Reg. $1250 $950°°

779-2 tractor feet

Reg. $1400 $1050°°

I Call lor Discount prices on Olher Centronics Printers

100 MHz 8-Dlglt Counter

• 200 Hz-100 MHz Range

• 6" LED Display

• Crystal-controlled timebase

• Fully Automatic

• Portable - completelyself contained

• Size • 1.75" x 7.38" x 5.63"

• Four power sources, i.e. batteries.110 or 220V with charger 12V withauto lighter adapter and external7.2-10V power supply.

$4343rSale $120.00

ACCESSORIES FOR MAX 100:

Mobile Charter Eliminator use power

from car battery Model 100-CLA $3.95.

Charger/Eliminator use 110 VAC

Model 100 — CAI $9.95

■'■U.IIWI'l, ■■■■ I. Iff "".■■' U.IMIL,

SALE

LOGIC MONITOR 1

Trace signals through all types of digital circuits. Unitclips over any DIP IC up to 16 pins. Each of its 16 contactsconnects to a single-bit level detector that drives a high-intensity, numbered LED readout activated when the ap-plied voltage exceeds a fixed 2 V threshold. Logic "1"turns LED on; logic "0" keeps LED off. A power-seekinggate network automatically locates supply leads andfeeds them to the LM-1's internal circuitry. Saves minutes,even hours In design, troubleshooting, debugging ofequipment. Voltage Threshold: 2 V t 0.2 V. Input Im-pedance: 100,000 ohms. Input Voltage Range: 4-15 V max.across any two or more inputs. Current Drain: 200 mA at 10V. Size: 4" I. x 2" w. x 1.75" d. when open. Weight: 3 ozs.CSC Model LM-1 Logic Monitor—Complete.Sale Price $54.95

PRIORITY ONE ELECTRONICS

16723B Roscoe Blvd. Sepulveda CA 91343

Terms: Visa, MC, BAC, Check, Money Order, C.O.D. U.S. Funds Only. CA residents add 6% sales tax.Minimum order $10.00. 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 Sept. 1979. OEM and Institutional

phone orders welcome (213) 894-8171. (800) 423-5633 inquiries invited.

ORDER TOLL FREE 1-800-423-5633 ORDER TOLL FREE 1-800-423-5633

.5%, 31/2 digit 19

Range DVM. Vt" LCD displays

runs 200 hrs on 1 battery. 10 Meg

Ohm Input. 1 yr. guarantee, made in

U.S.A., test leads included.

Available Accessories

RC-3 115V AC Adapter $7.50

CC-3 Deluxe Padded Vinyl

Carrying Case $7.50

VP-10 X10 DCV Probe Adapter/

Protector 10Kv $14.95

VP-40 40Kv DC Probe $35.00

CS-1 10 Amp Current Shunt $14.95

*FREE

Just for Asking.FREE BATTERY with your meter.

• fftQftKf ftKtMM wthjounct,coeor loOf plittd tf.a OMOurmlet". t-. lor ■an

• Soto* miu wiln MW wnaowS on

• Mour>-inrettGiKMKiiniO0UMJctl|2rwrllD" l?SunHrnnlh !M(W»»CingVBCIOi iu't numur Mll'2. « rnounli IGritIKIcipiulinKID' tiH"sion

• rnciij-jss richf rj c*Cu>U »"0 inuiuci-oni lo> ooi.on olMini* tHi« us. or "ailing l*rm.njtiont

> LfgtDuMl *SVmoGMDl104MPS)

*u!".■:■ Cuntrt.»r.noijit[>«MiL i'H.'i.iMM

1*1 SAl HOsa m<:«orisuir « tiurot' ourO

1„ Price:$29.50

RS232 & "D" TYPE CONNECTORS

P = Plug Male S = Socket-Female C = Cover-Hood

PART NO.

DE-9P

DE8S

DE-9C

DA15P

DA15S

DA1SC

08 25P

OB-25S

DB51212-1

DESCRIPTION9 Pm Mate9 Pin Female9 Pin Cover15 Pin Male15 Pin Female15 Pin Cover25 Pin Male25 Pin F»mnle1 pc. Grey HoodDB1226-1A 2 pc Black HoodD8110963-3 2 pc. Gray Hood

PRICE■4 S-9

HICKOK LX303 $74.95

3 LEVEL GOLD WIRE WRAP SOCKETS

Sockets purchased In multiples of 50 per type may be combined lor best price.

11

'nmuMfrUiM'inrJ

T\ 15

=i 1 2.2

50 130 1.15

DC37PDC37SDC37CDDSOPDO50SODSOC020418S

37 Pin Mai37 Pin Female37 Pm Cover50 Pin Male50 Pm Female50 Pin CoverHardware Set (2 pa

2.20 2.00

3.20 3.00

1.80 1.45

2.M 2.50

3.75 3.85

1.85 1.40

1.90 1.80

1.80 1.55

3.95 3 SO

575 5.50

2.20 1.95

4.95 47S

7.50 7.20

2.50 2.20

1.00 .80

Connector lor CENTRONICS 700 SERIES:Amphenol 57-30360 lor back of Centronics 700 Series printers 1.4-S900 5.UP-S7 50

S10O-WWO 50/100 Conl. .125 ctrs 3LEVEL WIRE WRAP 025" sq. posts on250 spaced rows GOLD PLATED1-4 5-0 10-34

1400 13 75 13.50

DIP

S100ALT 501100 Conl 125 ctrs

SOLDER TAIL on .140 spaced rows

ALTAIR motherboards GOLD Dialed

14 5.0 10-24

14.50 S4.25 14.00

DIP

S100STO 501100 Cont. .50LDER TAIL on 250 spaced rows loiVECTOR. IMSAI. CROMENCO motherboards GOLD plated.

1-4 50 10-24

S3.50 13.25 13.00

S10OSE 501100 Com 125 ctrs PIERCEDSOLDER EYELET tails GOLD1-4 5-6- 10-24

55.00 54.50 54.00

Other Popular Edge Connoctors

156 ctrs PIERCEDi. GOLD plated10-2452.20

53.55 53.70

IMSAI Slyle Card Guides 5/51 00

See our July Ad for many other connectors.

25-99 100-249 250999

Spin14 pin16 pin18 pin20 pin22 pin24 pin28 pin40 pin

.39.50.70.90.95.951.25

.36.38.42.60

.851.15

.34.36.40.55.75.80.801.00

.31.32.36.50.65.70.70.95

All sockets are GOLD 3 level closed entry. 2 level Tail, Low

Profile, Tin Sockets and Dip Plugs available. CALL FOR QUOTATION

APPLE PLUGBOARD

Vector 4609 Peripheral Interface Plugboard (or construction of custom circuits.Plug compatible with Apple II. Commodore PET and Super Kim microcomputers.Three connectors, in addition to the standard 25/50 system bus. are available forinput/oulput. A 20/40-contact card-edge connector, fabricated on the rear of theboard, mates with a 3-M type ribbon connector. Alternatively, a right-anglesolder-tail header may be positioned in this same location. The Model 4609 alsoaccomodates the miniature SIP-type connectors which may be placed on theperiphery or in mid-board.

1-4

5-9

10-24

$19.95 $17.96 $15.96

Plugboards

8800V

Universal Miciocompuler/ofocessorplugboard, use will) S-100 bus Com-plete with heal sink & hardware 5.3" it10' x 1/16

1-4 5-9 10-21

S19.95 S17.95 S15.96

8601-1

Same as 8800V except plain less powerOuses & Heal sink

1-4 5-9 10-24

$15.22 $13.79 $12.18

3682 9.6"x4.5"

S10.97

3682-2 6.5" X 4.5"

19.81

Hi-Density Dual-ln-LinePlugboard lor Wire Wrapwilh Power & Grd. BusEpoxy Glass 1/16" 44pin con. spaced .156

Phenolic

PART NO.64P44XXXP169P44XXXP

1M6 tfxfflt BOARD

.042 dia holes on

0.1 spacing for IC's

PRICESIZE 1-9 10-19

4.5x6.5" $1.56 $1.404.5x17" $3.69 $3.32

TRS-80/APPLE

MEMORY EXPANSION KITS4116's RAMS

from Leading Manutactumrs

<16Kx1 200ns)

8 lor $75.00

3677 9 6"x4.5"

$10.90

3677-2 6.5" X 4.5"

$9.74

Gen. Purpose D.I.P.Boards wilh Bus Patlernlor Solder or Wire Wrap.Epoxy Glass 1/16" 44pin ct n. spaced .156

r r

l

3662

6.5'

r

X 4.5'

m

$7.65

3662-2 9.6" x 4.5"

$11.45

P pattern plugboards forIC's Epoxy Glass 1/16"44 pin con. spaced .156

Add $3.00 for programming Jumpersfor TRS-80 Keyboard

IC SOCKET SALE

14 pin Low Profile10/&2.10 100/$1*».0016 pin Low Profile10/$2.20 100/S16.0024 pin Low Profile3/$1.00 40/S10.0040 pin Solder Tail3/$ 1.00 40/S10.00

24 pin Dip Plug with

cover

3/$1.004Q/$10.00

3690-12CARD EXTENDERCard Extender has 100 con-tacts 50 per side on .125centers-Attached connec-tor-is compatible withS-100 Bus Systems. $25.833690 6.5" 22/44 pin .156ctrs. Extenders $13.17^

3

14 & 16 PIN

GOLD 3 LEVEL

WIRE WRAP

SOCKES

14 - G3 100 for$33.00

16 - G3 100 for$33.0050 of each for $35.00 J

MEMORY MEMORY

2102LIPC Low Power 450ns in lots of 25 $1.102102AL-2 Low Power 250ns in lots of 25 $1.252114-3LlKx4 300 ns Low Power 8/S50.00

5257-3L4Kx1 300ns Low Power 8/550.00

2708 8K 450ns EPROM $9.00

271616K 5 Volt Only EPROM $45.00

Tg&&

PANAVISE TILTS. TURNS, AND ,ROTATES TO ANY POSITION.IT HOLDS YOUR WORK. EXACTLY WHERE YOU WANT IT.

WRAP. POST

for .042 dia. holes| {all boards on this page)IT44/C pkg. 100 . . S 2.34IT44/M pkg.

1000 $14.35

I A-13 hand installing

toot $ 2.94

IM-10A List $89.00

SPECIAL

556.95 with tubePerfectly balanced fluoroacont lightingwith precision magnifier lens. Toughthermoplastic shade. Easy lens re-moval. New wire clip design permitseasy Installation and removal offluorescent tube. Comes with plasticshield to protect tube from soiling anddamage.

Colors: Gray, Black, and Chocolate Brawn.Comas with on* 22 watt T-S Circlln* fiuoreacam tub^3dloptar janjL ^

I ELECTRONICS

*

ORDER TOLL FREE

1 80042356;

except CA., AK., Hi., Call(213) 894-8171

16723B Roscoe Blvd. Sepulveda CA 91343

Terms: Visa, MC, BAC. Check, Money Order, CO.D. U.S. Funds Only. CA residents add 6% sales taxMinimum order $10.00. Prepaid U.S. orders less than $75.00 include 5% shipping and handlingminimum $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 Sept. 1979. OEM and Institutional

hone orders welcome (213) 894-8171, (800) 423-5633 inquiries invited.

TEST

EQUIPMENT

CALL FOB

SPECIAL PRICES

ORDER TOLL FREE 1-800-423-5633 ORDER TOLL FREE 1-800-423-5633

Venus 2001Video Board

Assembled & Tested$259.95 •CompleteUnit with 4K Memoryand Video Driver onEprom assembledand tested $339.95

kit 199

95

OPTIONAL: • Sockets $10.00

• 2K Memory $30.00

• 4K Memory $60.00

• Video Driver Eprom $20.00

• S-100 plug-in • Parallel keyboard port

On board 4K Screen Memory (Optional). On board Eprom(Optional) for Video Driver or Text Editor Software.

Up and down scrolling through video

memory Reverse Video, Blinking Characters.

Display : 128 ASC11 Characters 64 X 32 or 32 X16 Screen format (Jumper Selectable). 7 by 11 DotMatrix Characters.

American or European TV Compatible

(CRTControls Programable) Dealer Inquiries Invited

32-K Static RAM $499.

• S-100 Plug-In • Kit includes P.C. board, all partsand assembly manual • Uses 2114L, 450 nS.

I.C. sockets-$20.00P.C. BOARD BY S-100 CO.

16-K Static RAM 249-

• S-100 Plug-In Kit includes P.C. board, all parts andassembly manual. Uses2114L450 nS.

Sockets-$10.00Add $40.00 for 300 nS (4MHz) RAMSP.C. BOARD BY WAMECO

z-80 cpu $125.

• S-100 Plug-In Kit includes P.C. boards, all partsand assembly manual.

FEATURES: 2MHz operation • S-100 plug-inPower-on jump • On board provision for 2708(optional at $12.95).

P.C. BOARD BY ITHACA AUDIO

ASCII Keyboard Kit $ 79.95

Assembled and Tested $95.95

• Single +5V Supply • Full ASCII Set (Upper and LowerCase) • Parallel Output • Positive and Negetave Strobe •2 Key Rollover • 3 User Definable Keys • P.C. BoardSize: 17-3/16" X 5" • Control Characters Molded on KeyCaps • Optional Provision For Serial OutputOPTIONAL: Metal Enclosure $27.50 • Edge Con. $2.00 •Sockets $4.00 • Upper Case Lock Switch $2.50 • ShiftRegister (For Serial Output) $2.00

Dealer Inquiries Invited

Apple II I/O Board Kit

Plugs into Slot of Mother Board

• 1 8 Bit Parallel Output Port (Expands to 3 Ports) • 1 InputPort • 15mA Output Current Sink or Source • Can beused for peripheral equipment such as printers, floppydiscs, cassettes, paper tapes, etc. • 1 free software listingfor SWTP PR40 or IBM selectric.

PRICE: 1 Input and 1 Output Port $49.001 Input and 3 Output Ports $64.00Dealer Inquiries Invited

new! A DREAM COME TRUE

lntroducing:30 MHZ

DUAL TRACEPORTABLESCOPE «„_

for an %CCCamazing \_r\JiJt

• Dual trace 2-channel; separate,chopped or alternate modes. • 30 megahertzbandwidth. • External and internal trigger.

• Time base - 0.05 .Microseconds to 0.2 SEC/div21 settings • Battery or line operation.

• Line synchronization mode.

• Power consumption less than 50W. • Vertical gain -0.1 to 50 volts/div-12 settings. • Size: 2.9" H 6.4"

W 8.5" D. • Weighs only 3.5 lbs. with batteries.

• Complete with input cable and rechargeablebatteries and charger unit.

OPTIONAL: Leather case $45.00 • 10:1 probe $27.00(2 for $49.00) ■■

MS-215

15 mhz Dual Trace Portable Scope $399.MS-1515 mhz Single Trace Scope $299.

MODELMS 230

SHIPPING $3.50 / California residents add 6% sales tax

ELECTRONICS WAREHOUSE Inc

15820 Hawthorne Boulevard

Lawndale, CA 90260

(213) 370-5551

Circle 130 on inquiry card.

Circle 1 on inquiry card.

FRFFI UPT0S170 IN' *■*■*■■ MERCHANDISEWITH THE PURCHASE OF ONEOF THE FOLLOWING PET-CBMITEMS!!

ASK ABOUT

EDUCATIONAL

DISCOUNTS

ON PET

$119.00$ 2.25$ 1.60

IEEE - RS232 Printer Adaptor for PETBETSI PET to S-100 Interface & MotherboardPET Connectors- Parallel or IEEE

- Cassette PortPersonal Information Management System-Add $3 for PET program cassette

Protect-A-Pet dust coverMICROCHESS for PET (Peter Jennings)PET 4 Voice Music Board (MTUK-1002-2)Music Software (K-1002-3C) for PETCmC Word Processor program for PETBridge Challenger program for PETAdventure 1 for 24K PETTunnel Vision/Kat & Mouse-mazeGraphics Utility Package for PETStimulating Simulations-Book & PET tape

Kite Fight - 2 player action game

Write for PET Software ListAuto-Repeat Hardware for PET

Word Processor for PET — Machine Language

version. Auto scroll, insert, delete, form letter append, etc.8K Version $ 24.00 16K or 32K with disk $ 95.00* Amount of Free Merchandise with Purchase of PET-CBM Item.

PET SPECIALS ust FREE*

PET 16N 16K full size graphics keyboard $ 995 $130

PET 16B 16K full size business keyboard $ 995 $130

PET 32N 32K full size graphics keyboard $1295 $170

PET 32B 32K full size business keyboard $1295 $170

PET 16S 16K small keyboard, integral cassette $ 995 $130

PET32S 32K small keyboard, integral cassette $1295 $170

PET 8K 8K small keyboard, integral cassette $ 795 $100

PET 2040 Dual Disk Drive - 343,000 bytes $1295 $170

PET 2040A Single Disk Drive - 171,000 bytes $ 895 $115

PET 2022 Traclor Feed Printer $ 995 $130

PET 2023 Pressure Feed Printer $ 849 $110

PET C2N External Cassette Deck $ 95 $ 12

$ 79.50

WRITE FOR 6502 ANDS-100 PRODUCT LIST

KIM-1 $159 (Add$30lorPowerSupply)SYM-1

BAS-1 Microsoft ROM Basic for SYMMemory Plus

SEA-16 New 16K Static RAMSeawell Motherboard-4K RAM

spaceKTM-2 Synertek Keyboard and

Video Interface with Graphics

CapabilityRAM 16 4MHz 16K Static S-100

2114 L 450ns 4K Static RAM2716 EPROM (5 Volt)6550 RAM (for PET 8K)6502 Microprocessor Chip6522 VIA6520 PIA

$222$ 85$199$325

$ 99

1.90

$ 9.50

$ 17.90

$ 49.00

$ 19.00

$ 25.00

$ 13.50

$ 7.95

$ 7.95

$ 13.50

$ 13.50

$ 7.95

$ 24.50'

FREE!

UP TO $170 INMERCHANDISE

BOOKS

Programming the 6502 (Zaks)6502 Applications Book (Zaks)6500 Programming Manual (MOS)Programming a Microcomputer:6502Basic for Home Computers

$290$270

$6.95$ 45$13.90$ 9.95$9.75$10.50

$ 9.90$11.90$ 6.50$ 8.90$ 5.90

3M "Scotch" 8" disks

10/$3I

3M "Scotch" 5" diskettes SALE

10/J35

Verbatim 5" diskettes

TO/527

(Write for quantity prices)

Minimum Order $10.00

A B Computers

Cassettes (all tapes guaranteed)

Premium quality, high output lownoise in 5

screw housing with labels:

C-10 10/5.95 50/25.00 100/48.00C-30 10/7.00 50/30.00 100/57.00

115-A E. Stump RoadMontgomeryville, PA 18936(215)699-8386

WAMECO

THE COMPLETE PC BOARD HOUSEEVERYTHING FOR THE S-100 BUSS

* FPB-1 FRONT PANEL BOARD * EPM-2 16K or 32K BYTE EPROM

Hex Displays, IMSAI Replaceable $54.95 2708 or 2176 interchangeable $30.00

* FDC-1 FLOPPY DISC CONTROLLER BOARD * QMB-9 9 SLOT MOTHER BOARDControls up to 8 Discs $45.00 Terminated $35.00

*MEM-1A 8K BYTE 2102 RAM Board ....$31.95 *QMB-12 12 SLOT MOTHER BOARD*MEM-2 16K BYTE 2114 RAM Board ....$31.95 Terminated $40.00

*CPU-1 8080A CPU Board * RTC REALTIME CLOCK

With Vector Interrupt $31.95 Programmable Interrupts ., $27.95

*EPM-1 4K BYTE 1702A EPROM $29.95

FUTURE PRODUCTS: 80 CHARACTER VIDEO BOARD,IO BOARD WITH CASSETTE INTERFACE.

DEALER INQUIRIES INVITED, UNIVERSITY DISCOUNTS AVAILABLE

AT YOUR LOCAL DEALER

W7J7C

iflC. WAMECO INC. 111 GLENN WAY #8, BELMONT, CA 94002 (415)592-6141

Circle 387 on inquiry card.

BYTE September 1979 245

Circle 384 on inquiry card.

10%OFF 20 OFF

YOUR OWN TRS-80 SYSTEM AT TREMENDOUS SAVINGS

Centronics 730Same as Line Printer II

Special 1st 25 units sold

OTRS-80 Complete System DISK DRIVES NOW IN STOCK/

Includes: CPU/ Keyboard, Power Supply,Video Monitor, Cassette Recorder, Manual,and Game Cassette.

©Line Printer

©Mini Disk SystemOC-10 Cassettes©Verbatim Diskettes

i

REG.PRICE

OURPRICE

$ 696.00 $ 557.10

ITEM

TRS-80 Complete SystemLevel II • 4K RAMTRS-80 Complete System

Level II 16 K RAM $988.00 $764.10

Expansion Interface $ 299.00 $ 269.10

Pertec FD200 Mini Disk Drive $ 495.00 $ 385.00

Centronics 779 Printer $1599.00 $1175.00

Centronics 101 Printer $1595.00 $1400 00

Anadex DP-8000 Printer $1295.00 $995 00

Centronics P1 Printer $ 534.00 $ 445.00

TrendatalOOO $1495.00 $1295.00

Memory KM16K) $ 199.00 $ 96.00■FREE INSTALLATION

Verbatim Diskettes ea. $ 595

3 $ 17.89

10 $ 59.00

Maxell Diskettes ea. $ 10.00

3 $ 30.00

10 $ 100.00

C-10 Cassettes 5 $ 4.95

25 $ 24.75

12 S 29.95fanfold.

C-30 Cassettes

Paper (9V;' x 11

3500 sheets)

Model

Level II—4KLevel II—16KExpansion Interlace

4.9512.0037 00

7.5021 0060.00

45018.7523 95

$ 35.00 $ 29.95

List Price Our Price

$698.00 $628.20

$988.00 $889.20

$299.00 $269.10

$ 850 Reg.$ 895

Anadex 9500

Similar to Line Printer III

$1,295 Reg. $1,999

* All printers include cables

There are new developments every day—write or call lor the latest information.

Outlet Hours:

Mon.-Fri.; 9 am.-Sat. 12—5 pm.

-7 pm.

777 Henderson Boulevard N-6Folcroft Industrial ParkFolcroft PA 19032(215) 461-5300

m

TOLL FREE

1-(800) 345-8102 'Orders only!

FOREIGN and DOMESTIC DISTRIBUTORSHIPS AVAILABLE

niiiitiiiiiiniiimimininiif

BUILD YOUR OWN LOW COSTMICRO-COMPUTER

POWER SUPPLIES

FOR S-100 BUS, FLOPPY DISCS, ETC.

POWER TRANSFORMERS (with mounting brackets)

ITEMNO.

USED INKIT NO.

PRI. WINDINGTAPS

SECONDARY WINDING OUTPUTS2x8 Vac 2x14 Vac 2x24 Vac

SIZEWx D x H

UNITPRICE

T1T2T3T4

0V, 110V, 120V0V, 110V, 120V0V, 110V, 120V0V, 110V, 120V

2x9A2X12.5A

2x9A2x4.5A

2x2.5A2X3.5A2x2.5A

2x2.5A2x4.5A

3%"x35/a"x3ya"3%"x4%"x31/8"3%"x4Wx31/b"3%"x3%"x3V8"

19.9525.9527.9519.95

POWER SUPPLY KITS (open frame with base plate, 3 hrs. assy, time)

ITEM USED FOR @+8Vdc @-8Vdc @+16Vdc @-16Vdc @+28Vdc

SIZEWxDxH UNIT PRICE

KIT 1 18 CARDS SOURCE 18A

KIT 2 SYSTEM SOURCE 25A

KIT 3 DISC SYSTEM 18A

KIT 4 DISC SOURCE 8A

1A1A

2.5A3A2A

2.5A3A2A

4A8A

12"x6"x4%"12"x6"x4%"14"x6"x4%"10"x6"x4%"

46.9554.9562.9544.95

EACH KIT INCLUDES: TRANSFORMER, CAPACITORS, RESIS., BRIDGE RECTIFIERS, FUSE & HOLDER, TERMINAL BLOCK, BASEPLATE, MOUNTING PARTS AND INSTRUCTIONS.

REGULATED POWER SUPPLY "R2" assy. & tested, open frame, size: 9" <w> x 5" (D) x 5" (H) $69.95

SPECS: +5V +1%, @ 5A, +24V, +1%, @ 5A. OVERCURRENT PROTECTION AND +5% ADJ. FOR BOTH VOLTAGES.REMARK: IDEAL FOR ROCKWELL AIM-65 MICROCOMPUTER. ALSO -5V, @ 1A OPTIONAL, $5.00 ADDITIONAL. -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.

MAIL ORDER:

P.O. BOX 4296

TORRANCE, CA 90510

SUNNY INTERNATIONAL

(TRANSFORMERS MANUFACTURER)Telephone: (213) 633-8327

STORE:

7245 E. ALONDRA BLVD.

PARAMOUNT, CA 90723

STORE HOURS: 9 AM-6 PM

246 BYTE September 1979

Circle 354 on inquiry card.

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16K EPROM CARD-S 100 BUSS

OUR

BEST

SELLING

KIT!

USES 2708s!

Thousands of personal and business systems aroundthe world use this board with complete satisfaction.Puts 16K of software on line at ALL TIMES! Kit featuresa top quality soldermasked and silk-screened PC boardand first run parts and sockets. All parts (except 2708's)are included. Any number of EPROM locations may bedisabled to avoid any memory conflicts. Fully bufferedand has WAIT STATE capabilities.

OUR 450NS 2708'SARE $8.95 EA. WITHPURCHASE OF KIT

ASSEMBLED

AND FULLY TESTED

ADD $25

8K LOW POWER RAM KIT-S 100 BUSS250 NS SALE!

'ADD $5FOR250NS!

$129

KIT

(450 NS RAMS!)

Thousands of computer systems rely on this rugged, workhorse, RAM board. Designed for error-free, NO HASSLE,systems use.KIT FEATURES:1

Doubled sided PC Board with soldermask and silk screen layout.Goldplated contact fingers.

2. All sockets included.

3. Fully buffered on all address and datalines.

4. Phantom is jumper selectable to pin67.

5. FOUR 7805 regulators are providedv on card.

Blank PC Board w/Documentation$29.95

Low Profile Socket Set...13.50Support ICs (TTL & Regulators)

$9.75

Bypass CAP'S (Disc & Tantalums)

$4.50

ASSEMBLED AND FULLYBURNED IN ADD $30 ,

16K STATIC RAM KIT-S 100 BUSS

\r

$279

KIT

PRICE CUT!

FULLY

STATIC, AT

DYNAMIC PRICES

.11 I I I I 1 I I I I I I I I I I1.........■.■■!■■

VJUkk

WHY THE 2114 RAM CHIP?

We (eel Ihe2114willbethenexi industry standardRAM chip (like the 2102 was} This means price.availability, and quality will all be good! Next, the2114 is FULLY STATIC We feel this is the ONLYway to go on the S-100 Buss' We've all heard theHORROR siones about some Dynamic RamBoards having trouble with DMA and FLOPPYDISC DRIVES Who needs these kinds otproblems7 And finally, even among other 4KStatic RAM's the 2114 stands outr Not all 4K staticRams are created equal! Some of the other 4K'shave clocked chip enable lines and various timingwindows fuil m critical as Dynamic RAM's Someof our competitor's 16K boards use these "tricky"devices But not us! The 2114 is the ONLY logicalchoice for a irouble-tree. straightforward design.

KIT FEATURES:

1. Addressable as four separate 4K Blocks.

2. ON BOARD BANK SELECT circuitry.(Cromemco Standard!) Allows up to 512K online!

3. Uses 2114 (450NS) 4K Static Rams

A ON BOARD SELECTABLE WAIT STATES5 Double sided PC Board, with solder mask andsilk screened layout. Gold plated contact fingers

6. All address and data lines fully buffered

7. Kit includes ALL parts and sockets.

8. PHANTOM is jumpered to PIN 67

9. LOW POWER under 2 amps TYPICAL from the■*6 Volt Buss.

10. Blank PC Board can be populated as anymultiple of 4K.

BLANK PC BOARD W/DATA—$33LOW PROFILE SOCKET SET-$12 ASSEMBLED & TESTED-ADD $30SUPPORT ICS & CAPS-$19.9S 2114 RAM'S-8 FOR $69.95 J

16K STATIC RAM SS-50 BUSS

s295

KIT

FULLY STATICAT DYNAMIC PRICES

KIT FEATURES:

FOR SWTPC6800 BUSS!

ASSEMBLED ANDTESTED - $30

1. Addressable on 16K Boundaries

2. Uses 2114 Static Ram

3. Runs at Full Speed

4. Double sided PC Board. Soldermask and silk screened layout.Gold fingers.

5. All Parts and Sockets included

6. Low Power: Under 2 AmpsTypical

BLANK PC BOARD—S33

COMPLETE SOCKET SET—S12

SUPPORT ICS AND CAPS-S19.95

NEW! G.I. COMPUTER SOUND CHIP

AY3-8910. As featured in July. 1979 BYTE! A fantasticallypowerful Sound & Music Generator. Perfect for use with any 8 BitMicroprocessor. Contains: 3 Tone Channel, Noise Generator, 3Channels of Amplitude Control, 16 Bit Envelope Period Control,2-8 Bit Parallel I/O. 3 D to A Converters, plus much more! All inone 40 Pin DIP. Super easy to interface to the S-100 or otherbusses.SPECIAL OFFER: $14.95 each Add $3 for 64 page Data Manual.

Initial slock very limited FIRST COME FIRST = EFIVED'

Z-80 PROGRAMMING MANUAL

By MOSTEK, or ZILOG. The most detailed explanationever on the working of the Z-80 CPU CHIPS. At leastone full page on each of the 158 Z-80 instructions. AMUST reference manual for any user of the Z-80. 300pages. Just off the press. $12.95

PROC. TECH. QUITS THE MICROPROCESSOR BUSINESS!

FACTORY CLOSE OUT - SPECIAL PURCHASE!

#16KRA

16K S-100 Dynamic Ram Board - $149.95

ORIGINALLY PRICED AT $429 each!

We purchased the remaining inventory of PT's popular16K Ram Board when they recently closed their plant.Don't miss the boat! These are brand new, fully tested,ASSEMBLED and ready to go. All are sold with ourstandard 90 day limited warranty!!

72 Page Full Manual, Included Free!

NOT ASSOCIATED WITH DIGITAL RESEARCH OF CALIFORNIA. THE SUPPLIERS OF CPM SOFTWARE.

Erf Digital Research: Computers

••;::: a <of texas>

•••••A P.O. Box 401565

GARLAND, TEXAS 75040 • (214) 271-2461

TERMS: Add soc postafic wpny hulanri' OidetsiinilpiNnCOH Wo arropt Visn MastcrCh.iitiP and Anioi.cnRes add 5", Tax Fntpipn ni dpi r (oxcrpt Canada add ^O"Rack Guarantor1 on alt Moms

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Circle 100 on inquiry card.

BYTE September 1979 247

Computer Products

i

The €xiclySORC6R6R

Flenbilty is the key. The Sorcerer Computer gives you the flexibility of using ready-to-run, pre-packaged programs or doing your own thing and personalizing the programs foryourself. Which ever you choose, the Sorcerer is the personal computer that speaks yourlanguage.

The Sorcerer also provides full graphics capabilties. Each character, formed by an 8 i 8

dot cell, can be programmed as a graphic symbol set. High resolution (512 x 240

addressable points) gives a total of 122.880 locations tor super animation and extremely

tight plotting curves. The alphanumeric set gives 64 x 30 characters on the video screen

PART NUMBER: SYO-S016A

With 16K of memory $1150.00

i mmmmmmmtmmmmmmmm I

Rockwell Aim-65: The Head-Stanin microcomputers

RKIM-1 compotible machine withon-board printer and o real key-boardl

1375.00 ui/IK ARM

MSO.00 w/4K RRM4K assembler/editor in ROM $808H BASIC in ROM: $ 100.00

Power Supply $59.95

Case of RIM-65 $49.95

Special Package Price: $599:00

AIM-65 I4K), Power SuoplV. Case, and 8K BASIC ROM

NOVATION iCAT RCOUSTic modgm

^■^ Features Include: 300 Baudonnn finsujer/Originote. Se" ' 03. ComesSI 89.00 Assembled ond Tested

PROTO BOARD

Includes gold platedfingers. S-100 size, holds72-16 pin dips, accomo-dates all 8 thru 40 pin dippackages.

Reg -S19 9S Special Prlce-$16.95 pART TSX-140B

SD SYSTEMSSBC-100

An S-100 single Doard compuler Z-80 CPU wilh 1024bylesolRAM 8lo32K bytesol PROM Sertal I O porlKit $239.95

fesserribjed $369.95

SD SYSTEMSZ-80 STARTER KIT

Baied on the powerful Z80CPU, this hit is an idealIntroduction to micropro-cessors, II has an on-boardkeyboard and display, plus

cassette tape Interface andexpansion provisions tortwo S-100 connectors. This"Do-it-ail" Board will alsoprogram the 2716 2KEPROM

Kit $249.95

Assmbld and Tstd $399 95

TEXTOOLZIP DIP* II

men. Sockets

16 pin Zip Dip II S5.50

24 pin Zip Dip II40 pm Zip Dip II

$7.50$10.25

INSERTION FORCE

LEEDEX MONITOR

• 12" Black ond While

• 12MHZ Bandwidth

• Handsome Plastic Case

$139.

rRSaO1 APPLE'SORCERER'TRS-BO'APPL

JADE MEMORYEXPANSION KITS ForTRS-80. Apple. & Exidy4116'i

Everything a person needs toadd 16K ol memory. Chipscome neatly packaged witheasy to follow directions. Inminutes your machine isready for games and moreadvanced software.

$82.00

HIGH QUALITY 13 INCH COLORMONITOR!— Specially matched loruse with the TI-99/4 console. Uses asimple, sure hook-up.UP TO 72K TOTAL MEMORYCAPACTIY— 16K RAM, plus up to26K ROM onboard, plus up to 30KROM In Tl's Solid State SoftwareCommand Modules.16-COLOR GRAPHICS CAPABIL-ITY- Easy to access high resolutiongraphics have special features thatlet you define your own characters,create animated displays, charts,graphs, etc.

MUSIC AND SOUND EFFECTS—Provides outstanding audiocapability. Build three-note chordsand adjust frequency, duration andvolume quickly and simply. You canbuild notes with short, straightfor-ward commands. Five full octavesfrom 110 Hz to beyond 40,000 Hz.BUILT-IN EQUATION CALCULA-TOR— Unique convenience featurehelps you find quick Solutions toeveryday math problems, as well ascomplex scientific calculations.

TSCFIS INSTRUMENTS

TI-99/4

HOM€CO/WUT6H

F€flTUR€S INCWD€ R COLOR MONITOR,16H RRM M6MORV, SRSIC BUILT INTO TH6CONSOie. RND TUJO COMPRCHCNSIVe MAN-UALS €ASV FOR THE Q6GINN6R - CHaieNG-ING FOR THe OPCRT.

Programs are sealed securely in SOLID STATESOFTWARE COMMAND MODULES. These ROMpacks actually add memory to the TI-99/4 so that theconsole's memory can be utilized (or user input.

The software applications are presently broken downinto lour areas: 1) Home Management/PersonalFinance. 2) Education. 3) Entertainment. 4) BASIC.

SVO-8994R $1150.00

JADE SERIAL/PARALLEL I/O BOARD

Features Include: S-100 Compatible ■ Two serial I/O Pons usingsoftware-programmable UARTS ■ One general purpose latched parallelI/O Port Ideal for printer Interlace or control ■ Switch selectable ■ Onboard "Kansas City" standard cassette Interface useable upto 1200 Baud,allowing storage of up to 180,000 bytes on a 30 minute audio cassette.Assembled and Tested Kit

IOI-1040A, $179.95 IOM040K $124.95

Bare Board with Manual IQM040B $30.00

SVM-l

Port Number:CPK-5002A

$245

6502- BASED SINGLE BOARD COMPUTER WITHKEYBOARD/DISPLAY, KIM-1 HARDWARECOMPATIBLE. COMPLETE DOCUMENTATION.

SVM-l CAS6. C-NX-000005 $39.95

THE BIG Z

THE NEW Z-80CPU BOARD FROM JADE

Features Include: ■ S-100 Compatible, available in 2MHz or 4MHzversions. ■ Onboard 2708. 2716. 2516. or 2532 EPROM can beaddressed on any 1K. 2K. or 4K boundary, with power-on jump toEPROM. ■ Onboard EPROM may be used in SHADOW mode,allowing lull 64K RAM to be used. ■ Automatic MWRITE generationit Iron! panel is not used. ■ On-board USART for synchronous orasynchronous RS232 operation (onboard baud rate generator). ■Reverse-channel capability on USART allows use with bufferedperipherals or devices with "not-ready" signal.

2MHz- BARE BOARD 4 MHz-

tmru CPU-302O0B....S40.00

KifCPU-30200K. 2 lbs $149.95 Kit: CPU-30201K, 2 lbs $159.95

Assembled and Tested: Assembled and Tested

CPU-30200A. 2 lbs $199.95 CPU-30201A. 2 lbs S209.95

-

GRI KEYBOARDS

Features Include: Full 128 character ASCII ■Trl-Mode Mos encoding ■ MOS/DTL/TTLcompatible output ■ Two-key rollover ■ Leveland pulse strobe ■ Shift and alpha lock ■Selectable parity ■ Positive or Negative Logic■ All new OEM grade components ■ Goldcontact, low bounce keyswithces ■ Rugged G-10 printed circuit board ■ Custom 2 shotmolded keycaps ■ Low power consumption ■Optional numeric pad available ■ Customenclosures available.Model 756A

Assembled- KBA-30756A $79.95

Model 753K (53 Key, Teletype Keyboard withlower case)

Kit- KBA-30753K $65.95

DB25-CONNECTORS

DB25P- CND1251 $2.25

DB25S- CND1252 $3.25

DB25C- CND1253 (Cover) $1.50

RS232 Special: DB25P, DB25S, plus Hoodonly $6.50 (Pari Number: CND-1250)

MICROPROCESSORS

F80 $16.95

280 <2MHz) $10.95

Z80A(4MHz) $14.95

CDP1802CD $19.95

6502 $11.95

6800 $9.75

6802 $14.00

S008-1 $15.95

8035 $24.00

8035-8 $24.00

8080-A $10.00

8085 $23.00

TMS9900TL $49.95

8080A SUPPORT DEVICES

8212 $2.90

8214 $4.65

8216 $2.75

8224 (2MHz) $4.30

8226 $2.75

8228 $6.40

8238 $6.40

8243 $8.00

8251 $7.50

8253 $20.00

8255 $6.40

8257 $18.00

8259 $18.00

8275 $51.20

8279 $17.70

USRT

S2350 $10.95

UARTS

AV5-1013A $5.25

AY5-1014A $8.25

TR1602B $5.25

TMS6011 $5.95

6800 PRODUCT

6821P $5.25

6828P $9.50

6834P $16.95

6850P $4.80

6B52P $5.25

6860P $9.25

6862P $12.00

6875L $7.30

6880P $2.50

CHARACTER GENERATORS

2513 Upper (1-12+5) $6.75

2513 Lower (1-12+5) $6.75

2513 Upper (5 volt) $9.75

2513 Lower (5 volt) $10.95

PROMS

1702A $5.00

2708 $9.95

2716 $49.95

2716 (5v) $49.95

2758 (5v) $30.00

DYNAMIC RAMS

4115 $5.00

416D/4116 (200m) $12.50

2104/4096 $4.00

2107B-4 $3.95

TMS4027/4096 $4.00

STATIC RAMS2114 (450ns)2114 (300ns)TMS4044/

MM5257(4S0m) $8.00TMS4044/

MM52S7(300m) $9.9521L02 (450m)21L02 (250ns)4200A (2O0m)410D (200n>)

1—15$8.00$9.00

$1.50$1.75$9.95$8.25

16—100

$6.95

$8.00

$7.50

$8.75$1.20$1.50$8.50$7.00

248 BYTE September 1979

Circle 195 on inquiry card.

£

PfilCeS GOOD IN TH€ UN[T€D SW€S AND CANADA

PI Af^E HCnCDC THl I CDCC. 800/421 -5«0» Continental U.S.L f\\-r C UnUt rSO I vLL rntt- 8OO/262-1710 Inside Calltomla

ULIhen visiting the Los Angeles areo, visit JflD€'s retail store at 13340 S. Houjthorne Blvd. in the city of Hoiuthorne

1

INTEGRAL DflTfi SVST6MS MOD6L 440 PRINT6R

TH€ PflP€R TIG€R

,Uptol98CPS $99500

I 1.75" to 9.5" Adjustable Tractor Feed

I Parallel and Serial Interface

I 96 Character ASCII Set

I 1 32 columns- 6 or 8 lines/inch

I Gight software selectable Character sizes

I 110, 300. 600. 1200 Baud Rate

fOfl THC- GRAPHIC OPTION WITH 2K. HDD J199 00

Part Number: PRM-33440

MEM-2

16 K Static RAM Board

KM-(450ns| $250 00

Kit. (250ns) $285 00

Assembled- (450ns) S325 00

Assembled- (250ns) S350 00

DYNAMIC RAM BOARDS

EXPANDABLE TO 64K32K VERSION. KITS

JSei Dili 18Kxl, 2b0ns) Dynamic3AM's, can oe expanded in 8Krements up to 32K

8K J159.95 24K $249 95

16K $199.95 32K $299.95

64K VERSION. KITS

-K.es 4116 (16Kx 1. ?00ns) DynamicHAM's, can De expanded in 16Kncrements up lo 64K

16K $249.9532K $369.95

48K $469.9564K S569.95

DIP SWITCHES

Pari No. positions 1-9SWD-103 3 $1.18SWD-104 4 $1.20SWD-105 5 $1.24SWD-106 6 $1.28

tft-tftftftftftftftf

SWD-107SWD-108SWD-109SWD-110

»l.30$1.34$1.36$1.38

CABLES

STATIC RAMBOARDS

JADE8K

Kit5: 450ns $125.95

250ns $149.75

Assembled & Tested:

450ns $139.75

250ns $169.75

Bare Board: $ 25.00

32K Static

Assembled & Tested:

250ns450ns250ns Kit

$795.00$725.00$575.00

L.S. EngineeringEPROM Eraser

Features Include: Erasesup to 48 I.C.s at a time •Uses popular (and readilyavailable 12* shortwaveUV bulbs) ■ Handsomesmoke-plastic case •Includes bulb •Just plug It in and you'reready to go!

XME-3200,

$39.95

POUU6R

supples

'SD-249A For a Single 5 1 4 Diskrive By Power-One or Alpha Power+5V it,7A, +12V at 1.1A .. $52.00

PSD-205A For Single B Disk Drive

By Power-One SV al 1A 5V at 5A.

24V at 1 5A S89 95

PSD-206A For Two 8 Disk DrivesBy Power One or Alpha Power 5V2 5A 5V at 5A 24V at

$125 00

Rockwell Aim-65 Power SupplyPSX 030A S59 95

KiM i or SYM-1 Power SupplyPSX-020A $*9 95

MINI-DISK CABLE KIT: To connedtwo 5 1/4" drives to disk controllerboard. Contains assembled and testec5' long signal cable with 34 pin edgeconnectors. Also includes cables andconnector tor D.C. power supply.WCA-3431K $34.95

8 DISK CABLE KIT: To connect two 8'disk drives lo edge-type controller(e.g.. Versalloppy. Ooubic-D)Contains assembled and tested signalcable wilh connectors plus cable andconnectors (or both A.C. and D.C.power.

WCA-5031K S38.45

8 DISK CABLE KIT: Same as WCA-5031K except controller end ol signalcable uses Header" lype connector,e.g.. tor Tarbell Controller.WCA-5032K S38.95

SIGNAL CABLE ONLY: For one 5 1/4"drive to edge type controller connector(e.g.. TRS-B0 to Vista Disk Drive).

WCA-3421A J24.95

Same as Above, except tor two 5 1/4"drives. WCA-3431A S29.95

JflD€

FLOPPY" DISKSPeCIAl

INCLUD€S: ■ Two Siemens/GSI 8"Floppy Dish Drives ■ Power Supply ■.lode Double Density Board (Kit) ■CP/MT" Operating System with Basic6 (CP/M is a registered trademark ofDigital Research) ■ Package of 10Blank 8" Diskettes (Double Density)■ Interface Cobles.

IF purchased seperately thispackage would cost: $1 544.95.

JfiD€ SP€CIAl$1225.00

JADE

ISO—BUSMOTHERBOARDSCornel In either 6, 12, or18 slot sizes. Theseboards with , a specialground plane assure asilent operationJADE 6 Slot

Kit $49.95

Assembled $59.95

Bare Board $24.95

JADE 12 Slot

Kll $69.95

Assembled $99 95

Bare Board S39.95

JADE 18 Slot

Kit $129.95

Assembled $149.95

Bare Board $59.95

THE PIGGY MAINFRAME

This steak new mainframe Is neatly trimmed to hold six S-100boards, three mini-floppy drives, and is available In five colors. Powerrequirements: 115/220 VAC, 50/60 HZ. Weight: 27 lbs. (with drives).Dimensions: 21.375" Wide X 8.4" High X15.675" Deep. Power Supply:8 volts at 16 Amps unregulated, + 16 volts at 3 amps unregulated,-16volts at 3 amps unregulated, + 5 volts at 3 amps regulated, +16 volts at3 amps regulated.

THE PIGGY IS HERE!

THE PIGGY (Without Drives). . .PART NUMBER: ENS-106320

S475.00

spezini

5'A" Diskettes$29.95/Box of T€N

SPeCIFV SOFT, 10. or 16 S€CTOR

8" SINGL6 SID6, SINGL6 DENSITY$34.95/Sox of T€N

TH€ JAD€ "DOUBl€-D"

INT6LLIG6NT

DISK CONTROLL6R

■ READ WRITE IN SINGLE OR DOUBLEDENSITY

■ X" or S'/i" DRIVES

■ CP M COMPATIBLE IN EITHERDENSITY

■ ONBOARD ZK0 CPU ALLOWSUNIVERSAL SYSTEM COMPATIBILITY

■ PROGRAMMED DATA TRANSFER-NODMA

■ CONTROLS UP TO S DRIVES

■ SOU WARE SELECTABLE DENSITY

Our new controller utili/cs the IBM standardformats for proven reliability. -Data recovery isCnchaccd through use of a phase-locked-loopdata sepcralion circuit and writeprecompensalion. Single and douhle densitydiskettes can he mixed in the same system.Assembled and Tested

IOD-I200A. 2 lbs. .. $299.95Kit

1OD-I200K. 2 lbs. .. $249.95Bare Board w; Manual

IOD-I200B. 2 lbs. . .. $55.00Manual

IOD-1200M. I lb. ... $10.00

Computer Products ■"■

4901 W ROSECRANS AVE.. HAWTHORNE, CALIFORNIA, 90250

(213)679-3313

ORDER TOLL FREE800-262-1710 pm 800-421-5809INSIDE CALIFORNIA ||§|j, CONTINENTAL U.S.WRITE FOR OUR FREE CATALOG

Cash, checks, money orders, and credit cards accepted.Minimum order $10.00, California residents add 6% sales tax.Minimum shipping and handling charge: $2.50. Discountsavailable at OEM quantities.

PflK€S SUBJ«T TO CHHNG€ WITHOUT PflrOfi NOTKC

For fetport information send for a JflD€ IOT€ftNATIONAl CATALOG

VB-1B VIDEO INTERFACE

S-100 Compatible Serial Inter-face with Sockets Included.Kit $117.95

Assembled & Tested $159.95Bare Board w/manual s 35.00

FLOPPY DISK INTERFACE

JADE FLOPPY DISK (Tarbellboard)

JADE KIT $190.00

Assembled & Tested $260.00

S.D. Computer ProductsVERSA-FLOPPY

K" S15995

Assembled 8, Tested S2 39 00

DISK DRIVES

MPI B51 5 1/4 " MSM-1SS10O $295.00Single or double density, up lo 40tracks, track to track access timeonly 5ms.

MPI B52 5 1/4" HSM-15S200 . $450.00Double head version ol MPI B51

Shugart SA400 5 1/4" $325.00

Single Density, 35 Track

Siemens FDD100-8 8" $495.00

Shugart 801R replacement, Single ordouble density, runs cooler andquieter.

Siemens FDD200-8 8" $575.00

Double head version ol FDD100-8capable of double density, doublesided storage.

Shugart 801R 8 "... $575.00

Hard or solt sectored, 400K BYTEdrive.

vista V80mini dish

SYSTEMFOR TRS—80$395.00.

PART NUMBER: MSM-35S000Includes disk drive, power supply,regulator board, and compact caseThe V-80 often 23% more storagecapacity. Simply lake it out of the box,plug in the cable, and it's ready to runRequires 16K. Level II. eipansloninterface.

Interface Cable .. $24.95

PART NUMBER: WCA-3421A

Circle 195 on inquiry card.

BYTE September 1979 249

Circle 296 on inquiry card.

COMMERCIAL GRADE PERIPHERALS FOR THE MICROCOMPUTEI

PRINTERTERMINALS

• '*»» I

MODEMS

TAPE DRIVES

•ASCII SELECTRIC PRINTER/TYPEWRITER: Why settle for less thanletter-quality printout from your computer? Refurbished IBM Model 725can be used as off-line typewriter or on-line printer. Complete with solenoids,power supply, case and ASCII interface card (TTL to CPU parallel port.)Interface includes programmable ASCII translation table on EPROM with up to8 tables for use with various type spheres. Feedback signals on completion ofeach print cycle insures fastest printing speed (15 cps.)

Price: programmed w/3 translation tables (one type sphere): $795.00

•SELECTRIC I/O TERMINALS (by GTE/Information Systems). Both ASCII& IBM code versions with microcomputer interface software & hardware (RS-232 connector.) Cassette drive models permit up to 2400 baud data transferrate as well as off-line data storage, use as memory typewriter, & use as dataentry device for office personnel familiar with Selectrtc typewriters but notcomputers. Wide-carriage, interchangeable type spheres; optional built-inmodem. All units cleaned, adjusted & warranted.

Model 5541 (IBM Correspondence code) $795.00

Model 5550 Icorres. code, built-in cassette drivel $1195.00

Model 5560 (ASCII code, built-in cassette drive). $1295.00

•DIABLO MODEL 1550 "DAISY-WHEEL" TERMINAL: Refurbishedletter-quality terminal with Hytype I printer (30 cps), full ASCII key-board, RS-232 serial prot, 110, 150, 300 baud, 768 char, print buffer,software controlled graphics mode (1/60 in. spacing), built-in stand.

SHIP WT. 200 lb. Price, refurbished: $1895.00

• DIABLO HYTYPE I Model 1200 PRINTER MECHANISM: used, completeand tested. Requires power supply, case & mCPU interface. 15 day return

privilege - no other warranties. LIMITED QUANTITYI $750.00

—6' Ribbon cable & connector for printer Main Logic PCB $10.00

—14-pin Winchester connector & 18" power supply cable $5.00

-"As-is" spare printer PCB's for parts (Logic, Heat Sink, Control): ea. $20.00-New Pin-feed Platen (14"): $50 if bought w/printer; separately .. . $100.00

• POS 103/202 "MIX or MATCH" MODEM: BELL 103 and/or BELL 202FREQUENCIES: Unique POS control design permits use in one housing ofboth Bell-compatible 103 (0 - 300 baud) and 202 (0 - 1200 baud) modemmodules originally made by VADIC Corp. for a telephone company subsidiary.FEATURES: RS-232 serial interface, auto-answer, auto-dial, LED display,telephone line interface via acoustic coupler, manual DAA, or auto-answerDAA (sold separately.) FULLY ADJUSTED; no special tools required.3,000 mile range over standard dial-up telephone lines.

-POS 103 MODEM (with Auto Answer, Auto Dial). $179.95

-POS 202 MODEM (Half-Duplex with Reverse Channel) $249.95

-POS 202 MODEM (Half-Duplex w/Rev.Ch., Auto-Answer) $279.95

-POS 103/202 MODEM (Auto-Answer, Auto-Dial) $399.95

• POS-100 NRZ1 TAPE DRIVE CONTROLLER/FORMATTER: Designed asinterface between S-100 bus mCPU and 9-track, 800 BPI, NRZ1 tape drive.Allows microcomputerist to read and write IBM-compatible %" mag tapes.Software provided for 8080 or Z-80 systems. Requires modification for drivesof various mfrs.

Price: (Includes S-100 card, controller card, 10' cable, software listing) . $750.00•NRZ1 TAPE DRIVE by WILLARD LABS. 9-track, 800 BPI, NRZ1 format,

12"/sec, 1200 ft. reels (10 megabyte capacity) Fully tested and warranted $599.00•CONVERT 15" IBM OFFICE SELECTRIC TO I/O TYPEWRITER: Kit

includes assembled solenoids, switches, wire harness, magnet driver.PCB plus

instructions for installation and mCPU interface $200.00

• DIGITAL CASSETTE DRIVE (from GTE/IS Terminal): 1800 baud, 6"/sec;AC motor; fwd/rewnd circuitry plus tape head, no read/write electronics $25.

•FORMS TRACTORS, Moore Variable width "Form A-Liner" for print terminals:

alModel 565P for 15" Carriage IBM Selectrics (new): $75.00

bIModel K81 for QUME or DIABLO Hytype I or II printers (new): .... $90.00

•POWER SUPPLIES for Disk Drive, mCPU, tested under load shown:-No. 519 Iw/fan & AC cord): +5V reg.,+12V reg., +24V, @4A (10 lb.). .$39.95-LAMBDA No. LMEE5w/OV protect: +5V reg. <§> 25A (35 lb.) $69.95

__^__________„ no RISKI 15 DAY APPROVAL ON ALL MAIL-ORDERS —^—

Full documentation included PLUS interface instructions K PACIFIC OFFICE SYSTEMS, INC. & Call or write for details, quantity prices, catalog. 15day

ra 918 Industrial Ave.

V Palo Alto, CA 94306

'\ (415)321-3866

where indicated. All equipment is shipped insured FOBPalo Alto within 14 days after check clears or CODorder is received. Prices may change without notice.

return privilege PLUS 90 day no charge replacement ofdefective parts. All orders shipped from stock. No backorders, no substitutions. M/C & VISA accepted.

ProComp/New England

9Z

C micRomflTion )

Specli

'ah

announces IMNET... (IMSAI Multi-user NETwork Operating System)

True Microcomputer Networks....Better than timeshared mini- or micro-systems....And less expensive. Stop by and see for yourself,Or write or call for our IMNET brochure.

10 Megabyte Winchester Disk, Integrated VideoComputer...$10,995. Other MicromationIntegrated Video Computer Systems from $5995.

Micromation Doubler Disk Controller...$395.'Measurement Systems & Controls48K Dynamic Flam...$595.

(617)482-4450120 Boylston Street

4th FloorBoston, MA/02116

Write, call or stop in (M-F 9-5;S 10-4) for our catalogand Grand Opening Sale Price List.

ProComp/New England

250 BYTE September 1979

-page-

Wire Wrap Tools

c*

sfr*

BATTERY HOBBY TOOL*

• Auto Indexing

• Anti-Overwrapping

• Modified Wrap

BW2628 Tool $19.85

BT30 #30 Bit 2.95

BT2628 #26 Bit 7.95

BC1 Batteries & Charger.. 11.00'Requires 2 "C" Niced Batteries

BATTERY INDUSTRIAL TOOL*

• Accepts Industrial Bits and Sleeves(Gardner Denver or equiv.)

• Industrial Motor for Production Wire-wrapping

• Backforce Avail. (Recommended for #30).

ELECTRIC INDUSTRIAL TOOL

• Accepts Industrial Bits and Sleeves(Gardner Denver or equiv.)

• Industrial Motor for Production Wire-wrapping

• Backforce Avail. (Recommended for #30).

BW928

Tool

49.95

BW928BF

Backforce Model

52.95

EW8

Tool

. 85.00

Bit & Sleeve

Specify #22-#30

29.50

EW28F

Backforce Model ..

. 92.90

BC1

Batteries & Charger..

11.00

Bit & Sleeve

#22 or#30

. 29.50

RN HIGH RELIABILITYeliminates trouble. "Side-wipe" contacts make 100%greater surface contactwith the wide, flat sides ofyour IC leads for positiveelectrical connection.

IC Sockets

WIRE WRAPSOCKETS

3-level GoldClosed Entry Design

All Prices Include Gold.

2-level SocketsAlso Available

1-9 10-24 25-99 100-249 250-1K

8 Pin14 Pin16 Pin18 Pin20 Pin22 Pin24 Pin

40

70.90.95.95

25 Pinst 1.2528 Pin 1.2540 Pin 1.65

36.39.4260.80.85.85.15.15

1.45

.34

.37

.40

.55

.75

.80

.80

1.00

1.00

1.35

.31.34.3650.65.70.70.95.951.20

.27.32.34.45.62.65.65.90.901.10

SOLDER TAIL

Low Profile Tin

1-9

10-24

25-99 100-249 250-1K

8 Pin

.21

.18

.16

.15 .14

Closed Entry Design

14 Pin16 Pin

—

.19

.21

.17.19

.15 .13.17 .15

18 Pin

.30

.28

.27

.26 .25

20 Pin

.35

.34

.33

.32 .31

22 Pin

.36

.34

.30

.27 .26

24 Pin

.38

.36

.32

.29 .28

28 Pin

.45

.44

.43

.40 .39

40 Pin

.63

.62

.61

.58 .57

OK PRODUCTS

WD 30

50 ft. Wire Dispenser, Red, White, Blue or Yellow $3.75

WD-30-TRI

TRI Color Dispenser 5.50

R-30-TRI

Refill for TRI Color 3.75

INS 1416

14 & 16 pin Insertion Tool 3.25

MOS40

40 pin Insertion Tool 7.50

EX-1

IC Extractor Tool 1.49

H-PCB-1

Hobby PC Board 4.99

WSU30

Hand Wrap/Unwrap/Strip Tool 6.25

WSU 30M

Same as WSU 30 with Modified Wrap 7.50

AVAILABLE AT

page

ORDERING INFORMATION

• Orders under $25, add $2 handling

• Blue Label or First Class, add $1 (up to 3 lbs.)

• CODs, VISA & MC orders will be charged shipping

• Most orders shipped next day.

135 E. Chestnut Street 5A, Monrovia, CaliforniaAT SELECTED LOCAL DISTRIBUTORS

Circle 299 on inquiry card.

91016 Phone (213) 357-5005

BYTE September 1979 251

*v^;

STATICW/RAM BOARDS.

nesPt

S-100 32K (uses 2114)

ASSEMBLED

450ns. 599.00 450ns.' 539.95

250ns. 699.95 250ns. 599.95

Bare Board 49.95

Bare Board w/all parts less mem. 99.95

8-10016K. (uses 2114) KIT (exp. to 32K)

450ns.250ns.

ASSEMBLED

450ns. 325.00

250ns. 375.00

Bare Board 49.95

LOOOSI8K

ASSEMBLED

450 ns. 169.95 KIT 450ns. 125.95

250ns. 189.95 250ns. 149.95

Bare PC Board w/Data $21.95Now over 1 year successful field experience-Special Offer" Buy (4) 8K 450ns. Kils S117.00

FLOPPY DISK DRIVES

1. VISTA v-80 MINIDISKFOR TRS-80

* 23% More StorageCapacity - 40 Tracks

* 40 track patch now avail.^*—"~^v

* Faster Drive - f,-__ -_\Up to 8 Times Faster l*"*WJ

2 Drive Cable Add $2995 > '

4 Drive Cable Add $39.95

2. VISTA V-200 MINI-FLOPPY SYSTEM

* 204K Byte Capacity -k w/CPM. Basic "E"•k Double Density Drive f -*^

* One Double Density I W-200 \Controller w/Case & P.S. V6e8-°0/

Add to your EXIDY, HORIZON,and other S-100 computers.

3. VISTA V-1000 FLOPPY DISK SYSTEM

* (2) Shugart 8" Floppy Disks ,

* Controller Card, Cable. jC7~5&.Case i P.S. CtlSSSS

* CPM & Basic "E", UeBS.0O/Instructions* Manual ^■—S

4. MPI B51-5V. 40 tracks 279.00

5. Shugart SA400-5W, 35 tracks.... 295.006.Siemens/GSIFDD100-8 8" 375.00

7. Shugart 800/801 fl 8" 495.00

8. PERSCI Model 277 Dual 1195.00

9. WANG0/8IEMENS 5V Drive ... 290.00

EXPANDORAM MEMORY KITS

* Bank Selectable * Uses 4115 or 4116

200 ns.

* Write Protect * Power 8VDC. ±16VDC

* Phantom * Lowest Cost/BitExpando32Klt(4115) Expando64Klt(4116)

8K $158.00 16K $248.95

16K $199.00 32K $369.00

24K $299.00 48K $469.00

32K $349.00 64K $565.00

IMS STATIC RAM BOARDS j,?

* Memory Mapping ir Low Power r^

* Phantom * Assembled & testedRecommended by Alphamlcrosystems

250 ns. 450 ns.

8K Static $209.00 $189.00

16K Static $449.00 $399.00

32K Static $799.00 $699.00

ANADEX PRINTER

Model DP-8000 compact, impact, parallel orserial. Sprocket feed, 60 cols,i 84 Ifnes/min., bi-directionalNew only $895.00

VERBATIM" DISKETTES 0>tl

* 5*" Minidiskettes • &&£Soltseclor, 10 Sector, 16 Sector' •W.-rt$4.25 Each, 10/39.95 nM^iwS

* 8" Standard Floppy Olsks * TaY* ISoft Sector, Hard Sector V$4.50 Each, 10/41.95

•Add 4.95 for 10 Pack in Deluxe Disk Holder

l EXORCISM COMPATIBLE

9600 MPU Module w/6802 CPU $495.00

9601 18 Slot Mother Board 175.00

9602 Card Cage (19" Retma Rack Mount)... 75.00

9603 8 Slot Mother Board 100.00

9604 Switch mode System Power Supply... .250.00

9610 Utility Prototyping Board 36.00

9616 Quad flK Eprom Module •""

9620 16 Channel Parallel I/O Module.... 295.009622 Serial/Parallel I/O Combo •*•

9626 8K Sialic RAM Module 295.00

9627 16K Static 460ns 495.00

9630 Card Extender 68.00

9640 Muttiple Programmable Timer

(24 Timers} 395.00

9650 8 Channel Duplex Serial I/O 395.00

96103 32/32 I/O Module 275.00

96702 32 Point Reed Relay Module 350.00

eaOO BARE BOARDS

9620-0 $45.00 9603-0 27.00

9626-0 45.00 9600 56.00

9650-0 45.00 96103 -.55.00

9601-0 60.00 96702 55.00

Also AMI EVK System In Stock

APPLE/EXIDY/EXPANDOTRS 80 16K-UPGRADE KIT

* IbK wiln Jumpers & Instructions

for either Level t or Level II $74.95

* 16K for Apple II Upgrade $74.95

Special: TRS80 Schematic S 4.95

Expansion Interface Schematic $ 4.95

TRS 80 TO S-100

PET TO S-100 ADAPTER

Allows Pet/TRS 80 to be interfaced topopular S-100 Bus.

Pet to S-100 Kit $189.95

Assembled $269.95

TRS80toS-10OHUH8100Kit....$275.00Assembled $355.00

KEYBOARD ASCII ENCODED

One time purchase ofNEW Surplus Key-boards. From the SingerCorporation. Thekeyboard features 128ASCII characters in a 63key format, MOSencoder circuitry "N" keyrollover, lighted shift lock, control, escape andrepeat functions. Ltd Qty <*3 KEY $69.95

UV "Eprom" Eraser

~ M<kUIUV«-11E 368.05Holds 4 Eprom's at a time.Backed by 45 yearsexperience.

Modal S-B2T... 9285.00Professional Industrial Model

TARBELL FLOPPY INTERFACE

* Z80/6080 S 100 Compatible * Umb CPM

Assembled (or Shugart SALI 9M9.0O

Assembled Other Drives $269.95

Kit $179.95

Bare Board $36.95(Doc. Add $10.00)

Nole: For CPM Add S70 00 Documenision Add (20.00

Vista Double Density 5'/*" Controller Assem $299.00

3D Versa Floppy Kit $159.95

SD Versa Floppy Assembled $189.95

Tarbel Casaelle I/O Kit $115.00

Sale * 1771-01 Floppy Chip $27.95

BYTE USER 8K EPROM BOARD

* Power on Jump * Reset Jump

Assembled & Tested $94.95

Byteuser Kit $64.95

Bare PC Board $21.95

Special Offer: Buy 4 kits only S59.95 each

MR-8 8K w/1 K Ram $99.50

MR-16 16K w/1 K Ram $99.50

EPM-1 4K 1702 $59.95

EP^^TOSor^Tlf^prtDrr^^^^SeS^S

Z-80/Z-80A/8080 CPU BOARD

* On board 2708 * 2708 included (450ns.)

# Power on jump * completely socketed

Assembled and tested $185.00

Kit $129.95

Bare PC Board $ 34.95

• For 4MHz Speed Add $15.00

8080A Kit $ 99.95

8080A Assembled $1 49.95

S-100 MOTHERBOARD SPECIAL

8 slot expandable w/9 conn.

rag $69.95 NOW $52.95

TARBELL FLOPPY CONTROLLER

Card assembled and tested for use with ShugartDrives $ SALE PRICE only $229.00

ACOUSTIC MODEM

NOVATION CAT™

0-300 Baud

Bell 103

Answer, Originate $198.00

ACOUSTIC COUPLER SPECIAL

AJ MODEL A30SPECIAL PURCHASEOF SURPLUS UNITSAVAILABILITY LIMITED $29.95

DATA BOOKS • COMPUTER BOOKS

1979ICMasier.. 49.ee In 1*1 MCS BO Manual 7.9S

NSC TIL Data 3.9B Inlet MCS 40 Manual 4.98

NSC Linen 4.99 AMD BOBOA Manual 5.95

NSC Linear App Notes II. 396 AMD Schotltiy Dslibook .. 4.95

NSC CMOS 3.96 AMI MOS/LSi Data 3.95

NSC Memory 3.95 01 MOS/LSI Data 498

Intel Databook 4.99 Harrla Analog. Dsiaoook.. 4.05

inlet MCS 85 Manual 7 SO Ti Linear Control Data 3.05

Intra lo MOM Vol 0 . >» 7.75

Intro to Micro* VOL I £*v 7 75

8080A Programming J6Q 7.75

6B0Q Prog ram mlng . 'B9 '■"*

ZBO Programming. e'SQ 7.75

Vol. II Some Real MMOprocaaaooi w/Btnder . .TrXJQ 27.50Vol. Ul Soma Real Support Device* w/B-nder . TQ-eo. 18 90

Intro lo Micros Vol III TtHtO. 1B.SO

•AIR a MUTHIUH COMHmR MOKI a le\L>

Undemtandtnfl Compoler* "B.96- 7.B5

aoeoMteiocompu'e. Etpartmanta... . TSteV 11.95

Beginning BASIC ... »•*. 8.95

Beginners Qtouary 6 Quick* SW 5.05

Psanul Butler 1 Jely Guide lo Compute™ TM. S.05

0080 Machine Language Programming .T.05. 8.95

Home Compulera Vol I Hardware . . .... .... -TAt 8.B5

Home Computer* Vol. " Software ,. . ... *t»«f> 11.95

THE FIRST TO OFFER PRIME PRODUCTS TO THE HOBBYIST ^

AT FAIR PRICES NOW LOWERS PRICES EVEN FURTHER!

1. PrOVCIl QtlSllty Factory tested products only, no re testsor fallouts. Guaranteed money back. We stand behind our products.

1979 CATALOG NOW AVAILABLE.

Send $1.00 for your copy of the most complete catalog of computer products. A mustlor the serious computer user.

MICROPROCESSORS STATIC RAM HEADQUARTERS SOCKETS

ZflOOO ...2-110

2-aoA

F-8 I3U50)2650C01802

3901

2901A

IMS 9900JL

CP1600

5502

6902A

IM6100

5500

6802P8035875587486809

..SCALLI4.M

18.95

.. 13.95

. 24.95

19.95

.49 95

6995

..I CALL..SCALL

SUPPORT DEVICES

AM95UAr,ih Pro. .",•-.-■'

AM 9511-1300 na

AM95T7 OMA Conlrollet

3881 1280 PIOl38S1-4I4MHH3BS2 IZ-BOCTCl3882-4 I4MHH

3883 510

3884 DMA

820&/74S13B Decode'S2i2 8b.ll/0S2i4Pno»1ymi

8218 But Driver

8224 Clock Gen

8224-4 (4MHi|

B226 Bui Driver

BI26 Bui Omre.

3228 Sys Control

S23B Sys Conl

8251 Prog I/O

B253 mi Time'

8299 Prog I/O

8357 Prog DMA

8259 Prog Inl

fl27SCHTConlio[ief

8279 Prog Keyboa-d .

6810-1 128 « 8 RAM

6620 PIA

6821 PIA

5828 Priority Int.

6834-1 512*8 Eprom

6850 AClA

6852 Serial Adlpler

6fl45'HD46505CRTC->nl

6860 Modem

6862 ModtrUjior

6871A 1 OMHrOSC

2 504.502502 959 75395239595625

49.09

18.064.755956.90695

25 958 252 39

1-24

25-99

100

1 30

125

21L02 250ns

1 69

1 55

145

2102

125

1 15

1.10

2111

3 75

3.65

3.55

2112-1

295

2 85

2.65

2.70

255

2ll4L-260ns.

12 95

995

2114L-300na

895

7 95

645

JI14L-450r.S.

750

575

4.73

4044/4041 300ns

995

8 75

795

4044/4041 490ns.

7.50

675

4.T5

EMM420OA

975

8 75

7 95

EMM4402

7.25

6 25

EMM4804

1250

11 SO

995

7 95

7 95

7 25

upd4IOI4200.

10 95

1025

9 25

AMOOI40/41

10 95

1025

9 25

AMD9130/31

12 95

11 95

10 25

FSC 460/46416« CCD Only 9

895 Each

1101

< 95

P212.V93425l46n-,

1 7 95

7 35

7 25

9508 IKil CMOS

7 95

7 95

7 25

6518 IK a 1 CMOS

7 95

7.95

725

745189 54 Oil Ram

3 95

325

250

2i47LowPowe>4XSta|fc 14

Seat

CHARGE COUPLED DEVICES

16KCCD ■Firsllimoc

'tared Fa

rchild 460 CCD

16K Memory (now yo

-iCCO

lochnology al a reasonable pnci

17 page Apples.

iKhordi

iim.ied)

$18.95 •«ch (rejg. 43.00)

25 00

6880 Bus DriverMC6B48B

1821 SCO IK RAM

1822 SCO 256 ■ 4 RAM1824 CO 32 i 8 RAM 9 951852 CD B oil I/O 10 951854 Uarl 10.95

1856 CD I/O . . . 895

1857 CO I/O 8 956920 PIA 7 906522 Mull 9 25'6530-002 . IS 506530-003 . 15 506530-004 15 506530-005 .15 50

DYNAMIC RAMS

416/4118 18K(i8Pln| . .... g.Q5

Selol84l8't 74.95

41 IS 8K [16 Pin) 6.95

4050 ik ■ 1 (ISPmi) .425

I (2? Pin) 4 95

I {IS Pin) .. 3 95

i (IflPin) 4.78

i I (16 Pin) 4 95

4050 4K>4096 4K i2104 4K.4027 4Ki

5261 195

6262 . 1955270 ...4955280 a 955290 12 45

PROMS

27082708-61702A2732

1103 .4008L

6-5V

12V

2513-001 (5V) Upper

..950

2513-005 |5V) Lower

. 10 95

2513-ADM3I5V) Lower

14 95

MCM6571A

MCM6574

MCM6575 .

14 50

UARTS/USRTS

7RI602BI5V, 12V) . .

Ay510l3(5V. 12V)

4.99

AV51014A/I6I2I5-14V1 .

AY51015A/186.1[5V|

IMS 6011 (5V. 12V)

1B71BAslro« .

2495

..B.B3

BAUD RATE OEM

WDH

9 95

KEYBOARD ENCODERS

AY52376 13 75

AYS-3600 .1375

HD0169 9.95

74C922 9.95

74CB23 B.U

A/D CONVERTERS

87008nil Binary.8701 10 bl Binary8703 8 :■'■■ TS9400 Vmi lo F'ag Conv.B750 3-1/2 Digit BCO140HL6 6oi! . .....

1408L8 8DI1 .DACOlA/D

13 5022.0C

1350

22 P.n 51 n

TEXTOOL ZERO

INSERTION FORCESOCKETS

16 Pm S 5 50 24 P-n S7 I

40 Pin 110 25

CONNECTORS

DS2SPIRS232I

DB25S Female

Hood.

Scrl w/Hood. Sale22/44 WAV. S/T, KIM43/86 W/W. S/T, MOT ..50/100 S-100 Connodo'»50/t00 S-100 Connector u

55 502 95650

CTS DIPSWITCHES

CTS206-4'51,75 CTS206-8 5195

CTS206-5 SI 75 CTS206-9 Si 95

CIS2056 Si 76 CTS206-I0SI9SCTS206-7 SI 75

CRYSTALS

attcroprocaaae* TI

Price

S5 85

> 8433

4 95

5 85

2 0IMH/

295

2 097152MIH

585

2 4S76MHt

3 571545MH/

150

4CMM/

4 96

4 I94304MH/

595

4 9I520MH*

5 95

SOMIU

4 95

5 06B8

3.'U3MHi

5 95

6 553610 0MHz

13 0MHz

18 0MHz13 432MHz20 0MHz22 1184 MHz27 0MHz36 0MHz48 0MHz10OKC

DISPLAYS/OPTO/LED'S

* THOMIfaT * CALC * CLOCK* *

DL 704 (CO, OL 707 (CAl 300" Red. 99

FND 357 (CCI 357" Red 9S

FND 500/503 (CO SOD-Red 99

FND 507/510(CA| 500" Red . .... ... 90

FND BOO/803 (CO 800'Red 1.7S

FND 807/810 (CA) 800" Red 1.7S

XAN 3062 .SOO" Q'oen 1.15

HP506 2-773 HCA) 300* Red 99

9 Dflii Bubble Mini Cale Ditpiey ....99

9 Digi! Panapiea DhUtaY 400* 9B

9 Digll Fluorescanl 300' 33

MAI003 12V Auto i:n»fc Module II 96

BdieMo'MAI003 w/Red Filter J 35

MA1002A LED 12 nr. Clock Module 1095

* H«X ENaWLAYt • IMCOOCO DISMJtrt *

HP 5062-7340 Red Handecmal 1536

HP 50827300 Red Nymenc 1446

TIL 308 Numeric w/Logic &M

TIL 308 Number w/Loglc 10 5

TIL 309 Number w/Logie aos

TIL 311 Ha»adeom»i 12-tW

MAN 2A.320" Red Aipna Numeric. 9*5

MAN 10A.270'Red AjphaNumenc B.99

NAKED PC BOARD SALE

z-aocpu iiiMcii ..

6O80ACPU

BK Sine RAM (Logcil16K Stain: RAM (2114)32K Sialic RAM (2114)Floppy i/O aarbem...Caiaelle t/O (Tarbell)

BKEprom|2706|

1702 Eprom Board...

270672716 Eprom (tmacaj. . 34 952706/2716Eprom(WMC) .30.00

nealiime Clock 34 85

ACPProtoBd.(3MConn.

Veclor 8800 Proto ... .

Wee lor 8803 11 Slot MB

ACP Emender w/Conn

Video Interlace (SSMi

Parallel Interlace ISSM1... 27 95

lSSIolMolherBoartJIWMCl 32 95

SSIOIMolhorBoardfWMC) .2995

8 SKjlMolnerpn panOa&ei 3495

S34 9534 9521952P95499539 95

29 9521 95

30 OC

19.9529 9515 9527 95

WAVEFORMGENERATORS

8038 Funcl^nCMC4024 VCOLM566 VCOKH.-206Fune1ic

Gem

FLOPPY DISK I/O

1771-01 8' « MinifloppyuPrj372 Nac Floppy1781 Dual Floppy1791 Dual Floppy

TV INTERFACES

PiiM-Verter

TV-1 Video Interface

Mooverler

MAR Modulator

49 952995

39 95

6508 99

-35 003500

2716-51

2758 5V

5203AO 11 95

5204AO 995

6834-1 1295

IM 5610 2 95

■ALE MM S* l • l.M

62S115 612 i B CTS) . 16.95

823123 32 ■ fl 2.50

B2S126 258i4 3.50

825129 256* 4 ITS) 3.60

B2S130S12i4(OO 6.50

NSC DM7578 32 * 6 3.95

CHARACTER OEN

SPECIAL PURCHASE(while supply lasts)

21L02-4 (450 ns) 100 @ 99$ ea.21L02-2 (250 ns) 100 @ $1.15 ea.TMS4060 NL 4K Dynamic RAMS(pullouts) $1.95 ea.

1488 Line Receiver 100 @ 75$ ea.

1489 Line Driver 100 @ 75* ea.1489 House Marked 100 @ 50$ ea.1496 L Demodulator 25 @ 75<t ea.

COMPUTER SPECIALS

LIST SALE

Apple II Plus W/16K 1195. 990.

IPSI 1620 Diablo RO 329

2695.

PET2001-18N 995. 895.

Anadex DP 0000

995.

695.

Exidy Sorcerer W/8K 695. 795.

Centronics Micro P-

595.

395.

Compucolor II w/8K 1495. 1395.

CenIronies Micro S-

595.

525.

Cromemco Sya III 5990. 4990.

SorocIO 120

995.

850.

Horiionlw/IBK 1599. 1349.

Teletype Model 43

1349.

1150.

TEI PI208 W/3ZK

HiPlol Plotter

dual (loppy & CRT

Hiplol Digitizer

795.

735.

(1 avail.) 4995 2995

Inlerltibe II

B95.

764.

Pascal Microenfline 2995 2395

* L!V»

LEDSRed. Yellow. Green. 185 6/1.00

MCT2 PnotoXSTRHFE 250,30V 99

4N25 Photo XSTR HFE 250, 30V 1.29

4N33 Ptvoio Darllngion 1.75

fnilOB Photo XSTRFlalLer»e....iALI 4/1.00

MONTHLY IC SPECIALS

LF1360BJFETAnloaMuni8blt 8 95

ICM7208 Seven Decade Counter 17.9*

ICM7207 OecatatOf ControHer 6 95

ICM7049 Precakm Sio/WatchTimer 22 95

ICL7107 3tt Digit A/D (LED) 14 99

ICL82U Voltage Relerence i 9S

LM380 eattery OP. Audio Amp ,3/IJW

LMlBSOQ/ound Fault IC j 1 00

LMieOOPhaae Lock Loop FMSiereo 3/1 DO

LM1820 AM Radio .- ' M

DS362B Dual Moa Senee Amp ? v)

H0ai.fi 4/19.95 '0147 ECLRam... SBC

148B/146B 2/199 LF358HBiFel ..3/1.99

22 Pin S/T SoekM 10/1.00 MCM14505 8.95

6323 Prom.... 2 95 74S69 3/1.99

MK5014Calc 2/1,89 74107N 6/1.99

74141N 3/1.99 75452N 6/1.99

6726/8726 2.39 741N-14 10/1.99

95H90 9.95 S65CN 5/1.99

6381 60 6S6CN 3/1.99

TV CHIPS/SOUND

AY38500-1 6 Oamei B/W . SAV38515 Color ConvenerAYMG03-1 Roartiace GameAY38605-1 Warlare GameAY36606-1 Wipeoul Game...AY38607-I Shoolinrj GatleryAY38910 Gim-ni Cnchet Sound

Generator 1

5N76477 TI Sound Gmerslr.MM5320/21 TV Synch GenMM5369 Preacaiei

LM18I

I OF

MM6710OO NSC Color T

Game

MM57104 Clock Qen. .RF Modulator w/Audio.

ass

396

395

695. 3.75■ 8 95

All Shemenll FCM or UPS. Oldenunder tl0O0Oadd5^handling and[Milage. Orders over S'OOOG add2.5°« handling & postage. Maalor-charge/ 11 ni A /American Express/COD accepted w/25*s Oonow Ca.i-lornia Rsudenti add 6^ ia» ForeignOrdan add 8«* handling. All partiprime factory tealed guaiameedAdd .35 centa for Data,flelarl pnemg may vary Irani MailOrder Pncng. All pricing subject lo

P. O. BOX 17329 Irvine, California 92713 Phone (714) 558-8813

TWX: 910595-1565

Retail Store Open Mon. SatLocated at 1310 "B" E, Edinger,Santa Ana, CA 92705

252 BYTE September 1979

Circle 4 on Inquiry card.

SFSKBH

CQMPmiS

P.O. Box 17329, Irvine, CA 92713(714)558-8813

BACK TO SCHOOL

COMPUTERSPECIALS

in mUm SALE $100.00 OFF... and it's COLOR

"The Compucolor II"

... a personal colorgraphics system lor the modern computer man...

•k Color Graphics 13" Color CRT

* Proven 8080A CPU System

* 16K Extended Disk Basic

* Up to 117* Key Keyboard

* Up to 32K* RAM

* Minidisk Drive 51.2K Bytes/Side ^~-^

Model 3 w/8K, 72 Key Keyboard, RS232 . f At| ■ ■ ($1496.00Model 4 W/16K, 72 Key Keyboard, RS232 siqo 00 • ■ ■{ $1695.00Model 5 W/32K, 72 Key Keyboard, RS232 OF j: ... J$1995.00

Options: 101 Key Keyboard Add $150.00

117 Key Keyboard Add $225.00

Formatted Diskettes 2/$19.95

Programmed Diskettes $19.95

Diskette Library Inc. Hangman, Othello, Math, Chess, Startrek,Blackjack, Cubic Tic TacToe, Finance Vol. I, Finance Vol. II, Bonds andSecurities, Assembler, Text Editor, Personal Data Base.

EXIDY SORCERER only $799.00

$799 w/8K$1099 w/16K$1249 W/32K$1449 w/48K

User programmable or use cartridges.Combines the desirable features ofthePET. APPLE and TRS-80 into a com-plete expandable computer system.

*#l/0 expansion kit $149.00

*•• Vista V-200 add-on mini-floppy for Exidy. (requires exp,module) w/CPM $699.00

+ + New Word Processing Pac

$99.00

* INCLUDES:

Keyboard & enclosure

90 day Warranty

MICROSOFT BASIC

Video & Cassette Cable

Complete Documentation

**S100 Expansion

Module Add $299.00

** Cassette recorder

Add $44.95

** Sanyo 9" Monitor

Add $169.95

KIM-1Now only$179.00

• ♦Power Supply Add $59.95

* #Cassette Recorder... Add$44.95

♦ •Sanyo 9" Monitor...Add $169.95Add enclosure $29.95.

COMMODORE"PET"

Delivery fromstock

Advanced 8KModel

only $775.00

SYM-1 in STOCK

Reg. $269.00

Now$249.00

* KIM-1 Compatible

* 4K ROM Monitor

* 1K Bytes 2114 RAM

* 65K Memory Expansion

* User EPROM 2716

** Power Supply Add $59.95

#* Cassette Recorder Add $44.95

** Sanyo 9" Monitor Add $169.95

School A group discounts available.Buy now and receive S100.00 worthof discount coupons: i.e.,

* SRM-1 1K Static RAM exp.

reg. 42.00 disc. $32.00

* PEX-1 I/O Port, reg. $60,00. disc. $50.00

* SYM BAS-1 Basic ROM (Microsoft)reg. $159.00 disc. $109.00

* KTM-2 CRT/TV Keyboard.

reg. $349.00 disc. $319.00

SYM Enclosure $39.95

AIM 65

$375.00

ADVANCED INTERACTIVEMICROCOMPUTER

* On Board 20 column alphanumericprinter

+ Alphanumeric 20 character display

* Terminal style Keyboard 54 Keys

* 6502 based CPU

w/1 K RAM $375.00*

W/4K RAM $450.00*

Assembler ROM ... Add $85.00BASIC IN ROM... Add $100.00

Power Supply Add$99.95

Enclosure Add $44.95

RCACOSMAC VIP

NEW LOW PRICE $249.00

Assembled. Regular price $299.95

w/Sanyo 9" Monitor $169.95

VP-590 Color Board 69.95

VP-595 Sound Board 49.95

VP-570 4K Expansion Board 95.95

VP-580 Expansion Keyboard 15.95

VP-700 Tiny Basic ROM 49.95

VP-710 VIP Game Manual 10.95

§

occ

O

u.

Ill

_lm

2

<

o

z

oo

oo>

N

0)

tow APPLE II PLUS $990.00

APPLE'S new upgraded APPLE II W/16K is now in stock andavailable for the lowest price ever, only $990.00. You can add:*• M & R Modulator for $29.95** Sanyo tape recorder for $44.95•* 16K upgrade kit for only $74.95 ea.This isa limited offer and we reserve the right tochange without notice.

NORTH STAR HORIZON ^oUILi density*

Now in stock North Star Z-80-based high-performance computer,

• 180K Bytes per Disk

# Z-80 Processor

• Motherboard

* 2 Serial+1 Parallel Port Avail.

* 16KRAM

Horizon I Kit Reg. $1599.00 Sale $1349.00Horizon II Kit Reg. $1999.00 Sale $1749.00North Star Double Density Disk Subsystem Kit

PROCESSOR TECHNOLOGY

SOL-20 DEALERS & USERS INVITED!

*****

We purchased Processor Technology's entire inventory ofspare parts, work in process, and finished goods. Thismaterial will be sold on a first come first served basis.Advanced will continue to support some SOL products on alimited basis so make sure you get a copy of our completeinventory listing and a place on our SOL mailing list.

• New SOL-20 w/o Memory

• SOL-20 Keyboards

• 8KRA Memory Boards Assembled

• NKRA Memory Boardsupto64K

$1295.00$139.95 i$129.95$CALL'

Plus more endless PTI bargains send for details.

WE TAKE B/A, VISA, AM. EXP. • ADD 2.5% HANDLING & POSTAGE • PRICES SUBJECT TO CHANGE W/O NOTICE

Circle 4 on inquiry card. BYTE September 1979

253

Widen the ability of your TRS-80

Vi/tol

MM

The Vista V80:$395

The Vista V80 MiniDisk System is the perfectway to widen the capabilitiesof your TRS-80* Micro-computer. Quickly andinexpensively. Our $395price tag is about $100 lessthan the Radio Shackequivalent. Our delivery timeis immediate (24 hour turn-around from our Santa Ana,Ca. factory). And our system isfully interchangeable. That'sjust the start.

It will give you 23%more storage capacity byincreasing useable storagefrom 55,000 to 65,000 bytesper drive with our newsoftware patch.

It can work 8 timesfaster than the TRS-80 Mini-Disk system, because track-to-track access is 5ms versus40ms for the TRS-80. Youcan realize this added speed

•TRS-80 ©Tandy Corp.

254 BYTE September 1979

once the new double diskexpansion interface isavailable without expensivemodification of the existingunit.

It has a betterwarranty than any comparableunit warranty available - a full120 days on all parts andservice. When you considerhow much more goes into theVista V80, that shows a lot offaith in our product.

A full 3 amp powersupply means you have 2V2times the power necessary tooperate the V80, and fullventilation insures that therewill be no problems due tooverheating.

The Vista V80 MiniDisk System requires Level IIBasic with 16KRAMExpansion interface (itoperates from the RadioShack interface system. It

comes complete with adependable MPI Minifloppydisk drive, power supply,regulator board and ventedcase. It's shipped to youready to run - simply take itout of the box and plug it in.You're in business. From thecompany that meansbusiness -Vista ComputerCompany.

The Vista Computer Company.Manufacturers of QualityComputer Systemsand Software.

714/751-9201

1320 East St. Andrews Place

Suite I, Santa Ana, Ca. 92705

Circle 378 on inquiry card.

The NEW Owners Of

Radio Hut

P.O. BOX 2015 GARLAND, TEXAS 75041ORDER BY PHONE—214-324-5509

* ANNOUCE:THE RETURN OFRADIO HUTSUPER SPECIALS!

The EXPANDORAM is available in versionsfrom 16K up to 64K, so for a minimum in-vestment you can have a memory systemthat will grow with your needs. This is a dy-namic memory with the invisable on-boardrefresh, and IT WORKS!

• Bank Selectable

• Phantom

• Power 8VDC, +16VDC, 5 Watts

• Lowest Cost Per Bit

• Uses Major Brand 16K RAMS

• PC Board is doubled solder masked andhas silk-screen parts layout

• Extensive documentation clearly written

SD EXPANDORAM

Complete kit includes all Sockets for 64K

Memory access time: 375ns, Cycle time:

500ns.J • No wait states required|j • 16K boundries and Protection via Dip

Switches• Designed to work with Z-80, 8080, 8085

CPU's

EXPANDORAM 64K Kit (16K Ram)

16K $219.00

32K $279.00

48K $359.00

64K $419.00

WITHOUT MEMORY $159.00

We carry a full line of SD Systems Products. Please write for catalog or call for prices

UNSCRAMBLERKIT

Interfaces with any monitor or scanner• Easily tuned • Full instructions included •Drilled fiberglass PC. Board • One hour as-sembly • Easy to install • Punched case

This unit can unscramble most anyscrambled frequency such as thenew Motorola scramble and so on.Only $37.95 A&T

TELE TAPE

Record important telephone conversationsnow with Tele Tape and your recorder. Eachtime your telephone receiver is picked up yourrecorder will start automatically and when youhang up it stops. Tape will be extra clear so youcan refresh your memory at a later date. Kitincludes everything except case and phonoplugs.

Assembled and Tested only$29.95

"VERSAFLOPPY" KIT

The Versatile Floppy Disk ControllerOnly $139.00

FEATURES: IBM 3740 Soft Sectored Com-patible. S-100 BNS Compatible for 2-80 or8080. Controls up to 4 Drives (single ordouble sided). Directly controls the followingdrives:

1. Shugart SA400/450 Mini Floppy

2. Shugart SA800/850 Standard Floppy

3. PERSCI70and277

4. MFE 700/750

5. CDC 9404/9406

BOWMAR 4 DIGIT READOUTARRAY

4 Jumbo .50" Digits In One ■Stick"!The Bowmar Opto-Stick. The best readoutbargain we have ever ottered. Has (our com-mon cathode |umbo digits with all segmentsand cathodes brought out. Increased versa-tility since any ot the digits may be used inde-pendently to fit your applications. Perfect forany clock chip, especially direct drive units like50380 or 7010 Also use in treq. counters.DVMs etc. For 12 or 24 hour format. (Withcolons and AM/PM indicator. I

$1.99

I— lllltffffftttlt

FLOURESCENT*READOUTS

No. DG8F. Seven segments, blue-green in color. Can be directlydriven by many MOS ICs. .3"character.

.49 Ea.

LEDS

Jumbo Reds 10/S1.00

Jumbo Green & Amber 51 St.00

U[ni Red S/St.00

Mini Green, Amber St Clear 6/S1.00

LED WIRING HARNESS*

A $10 VALUE!

Has one of our LED Rocket switches, onerotary switch, two jumbo LED lamps and twoPC edge connectors from desk top calculatorplant! 79c EACH

POWER SUPPLY

A very fortunate purchase. One of the bestindustrial quality REGULATED supplies wehave seen. High performance, small size. In-put is 120VAC. 60 HZ. Has the following regu-lated outputs: -5VDC at 800 MA: -15VDC at1 25 AMP: - 25 VDC at 1 SOMA.

$70.95

MINIATURE SPEAKERSPECIAL!

2 INCH —.8 OHM.PERFECT FOR CLOCKS! $.79

TO -5 HEATSINKS*

Similar to Thermalloy 2205G

Finned with insert.

5 for SI

ROCKER SWITCH*

HEAVY DUTY

S.P.D.T. 3A. 125V.A.C.

New, modern styling! 5 for$1

Z80 STARTER KIT

SD System's Z80 Starter Kit enables the noviceto build a complete microcomputer on a singleboard. Featuring the powerful Z80 microproces-sor the Z80 Starter Kit features: • Keyboard andDisplay • Audio Interface • PROM Programmer• Expansion and Wire Wrap Area • On BoardRAM • 4 Channel Counter/Timer • Z-BUGMonitor in PROM • I/O Ports.

This month's Special:

$219.95 Kit $369.95 A&T

SD SYSTEMS'STATE-OF-

THE ARTSBC-100

KIT$219.00

10.99

Color Burst Crystal

3.57 MHz 89C

TERMS:Add 30e postage, we pay balance. Orders under $15 add75c handling. No COD. We accept Visa, MasterCharge, and Ameri-can Express cards. Tex. Res. add 5% Tax. Foreign orders (exceptCanada) add 20% P&H. 90 Day Money Back Guarantee on all items

COMPUTER CORNER

zso cpu;s

Z80A 13.99

RELATED CHIPS

2114 (300ns) 5.99

Z80 PIO 9.95

Z80 CTC 11.95

2708 8.99

4115 8/34.95

4116 (200ns) 8/80.00

4116 (150ns) 8/100.00

DISC CONTROLLER1771 29.95

While in Dallas visit our retail store at Treehouse Shop-ping center. Garland Road and Jupiter.

Circle 317 on inquiry card.

BYTE September 1979 255

Fesdep Service

To get information on the products advertised in BYTE, fill out the reader service card with your name and address. Then circle theappropriate numbers for the advertisers you select from the list. Add a 15-cent stamp to the card, then drop it in the mail. Not only doyou gain information, but our advertisers are encouraged to use the marketplace provided by BYTE. This helps us bring you a biggerBYTE.

Inquiry No.

Page No.

Inquiry No.

Page No.

Inquiry No.

Page No.

Inquiry No.

Page No.

1 AB Computers 245 89

8 Administrative Systems 80 91

5 Advanced Access Group 110 964 Advanced Computer Products 252, 253 933 Aladdin Automation 77 94

6 Altos 21 9716 American Square Computers 174 126

12 Anderson Jacobson 215 9915 Apparat 234 B6

9 Apple Computer 25 102

10 AP Products 63 101

11 ASAP Computer Products 230 9519 ATV Research 172 100

7 Automated Computer Software Serv 123 11518 Automated .Simulations 212 12021 Avlonlc Enterprise 172 125

13 Axiom 144 130

14 Basic Time 187 13234 Beta (Div of Measurement 133

Systems & Controls) 154 134

31 Biotech Electronics 152 141

• Bits Inc. 191, 200 150

32 Buss/Charles Floto 172 159

• Byte Back Issues 213 16036 BYTE Books 113, 114 161

' Byte Subscriber 217 216

• Byte WATS 172

38 California Comp Systems 37 170

39 California Digital 235 16941 Roy J Canon 174 17543 CAP Electronics 52 176

45 Central Data 169 177

46 Centronics 73 178

47 Chrislin Industries 142

53 COMPCO 183

54 COMPCO 192 180

55 COMPCO 195 195

56 Compucolor Corp 39 200

• Computer Factory NY 155, 229 20170 Computer Furniture & Accessories 161 202

• Computer Headware 215 203

75 Computerland 68, 141, 153

66 Computer Mart of NJ 93 207

68 Computer Service Center 217 206

72 Computer Tax Service 223 20574 Computer Warehouse 217 208

73 Compulex 148 227

76 CT Micro Computer 60 215

77 CT Micro Computer 146 212

78 CT Micro Computer 147 213

79 CT Micro Computer 221 211

82 Contract Service Associates 211 214

83 Corvus Systems 47 277

84 Cover Craft 176 220

• Creative Software 223 221

80 Cromemco 1, 2 226

40 CTC 104

87 Cybernetic Micro Systems 177 210

85 Cybernetics Inc 224 211

88 Cygol 217 223

Data Access Corp 165 204

Data Discount Center 221 *Data/Print Publishing Co 168

Datasearch 222 218Datasoulh Computer Corp 194Data Terminals & Communications 185 198

Data-Trans 238 222

Diablo (Div of Xerox) 79 209

Digital Pathways 167 224

Disks Etc 213 225

Dontho Scientific 210 231

DRC (CA) 221 230

DRC (TX) 247 236

Electrolabs 228 237

Electronic Control Technology 213 255

Electronic Systems 236, 237, 238 256

Electronics Warehouse 244 257

Escon 83 258

Falcon Publishing 210 278

FMG Corp 32 279

Glmix 88 281

Godbout Electronics 173 289

H & E Computronics 197 280Hamilton-Avnet 85

Hayden Book Co 138 282

Heath Company 17 283

Heath Company 105 284

Hobby World 226, 227 285

Industrial Micro Systems 139 286

Information Unlimited 150, 151 290

Integral Data Systems 49 291

Integrand 178 288

International Design Engineering 287

Assoc (IDEA) 217 293Intersystems 157

Intertec Data Systems 135 295

Jade Co 248, 249 292Jameco 232

Jameco 233 294

KML Marketing Inc 184 296

Kybe Corporation 69 298

Lifeboat Associates 90, 91, 149 299

Loweco Computer 217 297

Macrotronics 217 304

Marketllne Systems 171 305

Matrox Electronic System Ltd 44 306Paul McCoy Enterprises Inc 220Measurement Systems &.Controls 209 301

Micro Age 201 302

Micro Ap 205 308Micro Applications Group 222

Micro Architect 212 309Microcomputing Technology Inc 234 303

MicroDaSys 26 3t2MicroDaSys 75

Micro Designs 170 374

Micro Diversions 5 315

Micro Focus 64 321

Micro Integration 128 311

MICROMAIL 219 323

Micro Mike's 224 310

Micropolis 108, 109 317

Micro Pro International 56, 57 318

Microsette 172 314

Microsoft 127 322

MicroSoftware (CAI) 210 334

Microsource 13 324

Microtek Inc 59 325

Mlcrotel Inc 147 316

Microware 164 331

The Micro Works 158 *

Mikos 231 320

Mini Computer Suppliers 176 329

Mission Control 189 336

Morrow/Thinker Toys 31 330

Morrow/Thinker Toys 43 319Mountain Hardware 143

Mountain Hardware 186 337MVT Microcomputer Systems 45 328

National Technical Schools 210 "

NEECO 94, 95 327

NEECO 159 332

Netronics 87 333

New England Recruiters 174 335

New World Books 134 340Newman Computer Exchange 225 351

Northeast Computer Show 203 352

North Star Computers 27 353NRI Schools/Electronics Div 193 354

Ohio Scientific Instrument CIV 357

OK Machine and Tool 220 359Oliver Advanced Engineering 178 356

Omikron211 349

Omni Computer Corp 179 358

onComputing 97 355

Organic Software 174 350

Osborne & Associates 199 362

Owens Associates Inc 124 360

Pacific Exchanges 172 365

Pacific Office Systems 250 363

Page Digital 55 364

Page Digital 251 367

PAIA Electronics 221 368

PerCom Data CI 11 369PerCom Data 111

PerCom Data 239 366Personal Computing 79 180, 181 313

Personal Software Inc 51 379

Personal Software Inc 53 377

Pickles and Trout 177 378

Potomac Micro Magic 219 384

Power One Inc 89 387

Practical Applications 179 388

Priority I 241, 242, 243 389

Pro Comp/New England 250 391

Prog 80 163 393

P S Software House 172 394

Quality Software 224 401Quest Electronics 240RSI 33

RACET Computes 136

Radio Hut 255

Radio Shack 137

Radio Shack Auth Sales Center 171

RCA 103

RCA 132

RNB 146

RNB 160

S-100lnc218

S C Digital 204

St Jude 217

Sara-Tech Electronics 134

Frank Schiele 174

Scientific American 81

Seattle Computer Products 224

Michael Shrayer Software 145

Shugart Associates 6, 7

68 Micro Journal 175

Smoke Signal Broadcasting 122

Software Development and Training 156

Software Dynamics 212

Software Exchange 222

The Software Farm 174 .

Solid State Music 61

Solid State Sales 231 '

SONTEX Inc 174

Southern Systems of Birmingham 140

SubLOGIC 83

Sunny International 246

SuperSoft 175

SuperSoft 212

SWTPC CM

Sybex 125

Sybex 159

Synchro Sound 119

System Engineering Enterprise 131

Tano 133

Tarbell Electronics 11

Technical Software Inc 174

Technical Systems Consultants 117

Technology Transfer Inc 207

Thermax 217

3M Company 19

Robert Tinney Graphics 36

Tora Systems Inc 174

TransNet Corp 166

TRS-80 Software Exchange 162

US Robotics 72

Vector Electronic Co Inc 126

Vista Computer 254

V R Data 246

Wameco 245

Whitesmith's Ltd 222

Wintek Corp 172

Worldwide Electronics 172

X-Comp 92

X-Comp 170

Zs Systems 204

ECM6-

GYTE's Ongoing Monitor Box

'Correspond directly with company.

Article No.

ARTICLE

Page

June BOMB

1 Ciarcia: Joystick Interfaces

2 Dahmke: Introduction to Multiprogramming

3 Teeters: Interface a Chessboard to Your KIM-1

4 Ellis: Some Musings on Hardware Design

5 Hallgren: A Low-Speed Analog-To-Digital Converter

6 Trimmer: Soldering Techniques

7 Powers: The Nature of Robots, Part 4

8 Harron: Inexpensive, Optical Paper-Tape Reader

9 Albus: A Model of the Brain for Robot Control, Part 4

10 Chrisp: Handy Pulser

11 Kasser:The Amsat-Golem-80

12 Barbier: Add Some Control to Your Computer

10

20

34

62

70

84

96

118

130

160

182

196

William D. Johnston again dazzled ourreaders with "Computer GeneratedMaps," Part II, page 100. Second placewas taken by James Albus for con-tributing "A Model of the Brain for RobotControl," page 10. Placing a very closethird and fourth, respectively, were G. A.Van den Bout, "Designing a CommandLanguage and T. Radhakrishnan and M.V. Bhat, "Stacks in Microprocessors."

256 September 1979 © BYTE Publications Inc

Low Cost Add-On Storage for Your TRS-80

In the Size You Want.

When you're ready for add-on disk storage, we're ready for you.Ready with six mini-disk storage systems — 102K bytes to 591K bytes of

additional on-line storage for your TRS-80*.

• Choose either 40-track TFD-100™ drivesor 77-track TFD-200™ drives.

• One-, two- and three-drive systems im-mediately available.

• Systems include Percom PATCH PAK#1™, on disk, at no extra charge. PATCHPAK #1™de-glitches and upgradesTRSDOS for 40- and 77-track operation.

• TFD-100™ drives accommodate "flippydisks." Store 205K bytes per mini-disk.

• Low prices. A single-drive TFD-100TMcosts just $399. Price includes PATCHPAK #1™ disk.

• Enclosures are finished in system-compatible "Tandy-silver" enamel.

Whether you need a single, 40-track TFD-100™ add-on or a three-driveadd-on with 77-track TFD-200™s, youget more data storage for less moneyfrom Percom.

Our TFD-100™ drive, for example,lets you store 102.4K bytes of data onone side of a disk — compared to 80Kbytes on a TRS-80* mini-disk drive —and 102.4K bytes on the other side, too.Something you can't do with a TRS-80*drive. That's almost 205K bytes permini-disk.

And the TFD-200™ drives provide197K bytes of on-line storage per drive

— 197K, 394K and 591K bytes for one-,two and three-drive systems.

PATCH PAK #1™, our upgradeprogram for your TRSDOS*, not onlyextends TRSDOS* to accommodate 40-and 77-track drives, it enhancesTRSDOS* in other ways as well. PATCHPAK #1™ is supplied with each drivesystem at no additional charge.

The reason you get more for lessfrom Percom is simple. Peripherals arenot a sideline at Percom. Selling disksystems and other peripherals is ourmain business — the reason you getmore engineering, more reliability andmore back up support for less money.

In the Product Development Queue ... a printer interface for using your TRS-80* with anyserial printer, and ... thef/ecfr/c Crayon™ to map your computer memory onto your color TVscreen — for games, animated shows, business displays, graphs, etc. Coming PDQ!

PERCOM DATA COMPANY, INC.211 N. KIRBY • GARLAND, TX. • 75042

™ TFD-100, TFD-200. PATCH PAK and Electric Crayon are trademarks ot PERCOM DATA COMPANY.

•TRS-80 and TRSDOS are trademarks ot Tandy Corporation and Radio Shack which have no relationship to PERCOM DATA COMPANY

To order add-on mini-disk storage for your TRS-80*,or request additional literature, call Percom's toll-freenumber: 1-800-527-1592. For detailed Technical infor-mation call (214) 272-3421.

Orders may be paid by check or money order, orcharged to Visa or Master Charge credit accounts. Texasresidents must add 5% sales tax.

Percom 'peripherals for personal computing'

Circle 304 on inquiry card.

The Microcomputersyou should take seriously.

The Challenger III Series is Ihemicrocomputer family with the hardwarefeatures, high level software and applica-tion programs that serious users inbusiness and industry demand from acomputer system, no matter what itssize.

Since its introduction in August, 1977,the Challenger III has become one of themost successful mircocomputer systemsin small business, educational and in-dustrial development applications.Thousands of Challenger Ill's have beendelivered and today hundreds ofdemonstrator units are set up at systemsdealers around the country.

Now the Challenger III systems offerfeatures which make their performancecomparable with today's most powerfulmini-based systems. Some of thesefeafures are:

Three processors today, moretomorrow.

The Challenger III Series is the onlycomputer system with the three mostpopular processors— the 6502A. 68B00and Z-80, This allows you to take max-imum advantage of the Ohio Scientificsoftware library and the tremendousnumber of programs offered by independ-ent suppliers and publishers. And allChallenger Ill's have provisions for thenext generation of 16 bit micros via their16 bit data BUS, 20 address bits, andunused processor select codes. Thismeans you'll be able to plug a CPU ex-pander card with two or more 16 bitmicros right in to your existingChallenger III computer.

Systems Software for threeprocessors.

Five DOS options including develop-ment, end user, and virtual data filesingle user systems, real time, timeshare, and networkable multi-usersystems.

The three most popular computerlanguages including three types of BASICplus FORTRAN and COBOL with more C3-BCircle 290 on inquiry card.

languages on the way. And. of course,complete assembler, editor, debuggerand run time packages for each of thesystem's microprocessors.

Applications Software for SmallBusiness Users.

Ready made factory supported smallbusiness software including AccountsReceivable, Payables, Cash Receipts,Disbursements, General Ledger, BalanceSheet, P & L Statements, Payroll. Per-sonnel files. Inventory and Order Entry asstand alone packages or integratedsystems, A complete word processorsystem with full editing and output for-matting including justification, propor-tional spacing and hyphenation that cancompete directly with dedicated wordprocessor systems.

There are specialized applicationspackages for specific businesses, plusthe vast general library of standardBASIC. FORTRAN and COBOL software

OS-DMS, the new software star.

Ohio Scientific has developed aremarkable new Information Manage-ment system which provides end user

The Challenger 111

Series

from Ohio Scientific.

C3-S1

intelligence far beyond what you wouldexpect from even the most powerful mini-systems. Basically, it allows end users tostore any collection of information undera Data Base Manager and then instantlyobtain information, lists, reports,statistical analysis and even answers toconventional "English" questions perti-nent to information in the Data Base.OS-DMS allows many applications to becomputerized without any programming!

The new "GT" option heralds the newera of sub-microsecondmicrocomputers.

Ohio Scientific now offers the 6502Cmicroprocessor with 150 nanosecondmain memory as the GT option on allChallenger III Series products. Thissystem performs a memory to registerADD in 600 nanoseconds and a JUMP(65K byte range) in 900 nanoseconds.The system performs an average of 1 5million instructions per second executingtypical end user applications software(and that's a mix of 8. 16 and 24 bitnstructionsl).

Mini-system Expansion Ability.

Challenger III systems offer thegreatest expansion capability in themicrocomputer industry, including a fullline of over 40 expansion accessories.The maximum configuration is 768Kbytes RAM, four 80 million byte Win-chester hard disks. 16 communicationsports, real time clock, line printer, wordprocessing printer and numerous controlinterfaces.

Prices you have to take seriously.

The Challenger III systems havephenomenal performance-to-cost ratiosThe C3-S1 with 32K static RAM, dual 8"floppies, RS-232 port. BASIC and DOShas a suggested retail price of under$3600. 80 megabyte disk based systemsstart at under $12,000, Our OS-CP/M soft-ware package with BASIC, FORTRANand COBOL is only $600. The OS-DMSnucleus package has a suggested retailprice of only $300, and other options arecomparably priced.

To get the full story on the ChallengerIII systems and what they can do for you,contact your local Ohio Scientific dealeror call the factory at (216) 562-3101.

C3-B wins Award ol Merit alWESCON 78 as the outstandingmicrocomputer application lorSmall Business

C3-OEM