Byte Magazine Volume 03 Number 03 - Computer Music Systems

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by any other

micro-computersystem

COMPUTERSTERMINALSPRINTERSSOFTWARE

TAPE SYSTEMS

DISK SYSTEMS

GRAPHICS

PROM PROGRAMMER

MEMORY - 4K, 8K, 16K & 32KPROGRAMMABLE REAL TIME CLOCKCALCULATOR INTERFACEA-DCONVERTER

Write, or circle our reader reply number for a catalog describing our complete line of computer hardwareand software.

NOW AVAILABLE IN BOTH KIT AND ASSEMBLED FORM.

SOUTHWEST TECHNICAL PRODUCTS CORPORATION

219 W. RHAPSODY

SAN ANTONIO, TEXAS 78216

Circle 113 on inquiry card.

Now we can announce it-

the multi-disk driveSystem Three Computer

A fast Z80 microcomputer with up to 512 kilo-bytes of RAM, 4 disk drives and 1 megabyteof disk storage—with CRT terminal and fastprinter. Even an optional PROM programmer.Strong software support, too, like FORTRANIV, Extended BASIC, and Macro Assembler.

PROFESSIONAL GRADE—FOR PROFESSIONALS

Chances are you've already heardthat there is a Cromemco SystemThree Computer. We've proudly pre-viewed it at WESCON on the WestCoast and NYPC on the East Coast.

But you also know Cromemco. Wedon't announce until we're ready toship.

Now we're ready.

And what a computer we've gotfor you.

It does it all.

It's a complete system—processor,CRT terminal, line printer.

First,it's fast—1 microsecond nom-inal execution time and 250 nano-second cycle time.

Its equally fast RAM memory islarge and enormously expandable—32 kilobytes expandable to 512 kilo-bytes. No danger of obsolescencefrom inadequate RAM capacity.

THE ONLY MICROCOMPUTEROFFERING 4 DISK DRIVES

Further, the System Three comeswith two disk drives to give you 512kilobytes of disk storage. Soft-sectored IBM format. Optionally, youcan have four drives with 1 mega-byte of storage.

There's disk protection, too, sincein the LOCK position disks can't beejected while they are running.

21-SLOT MOTHERBOARD

This new CS-3 is a computer thatwon't be outdated soon. It has a 21-card-slot slide-out motherboard andan S-100 bus so that you can plug inall sorts of support circuitry. Theheavy-duty 30-amp power supply caneasily handle all this.

BROAD S-100 SUPPORT

The S-100 is the bus that Cro-memco so strongly supports withover a dozen plug-in circuits ranging

from analog I/O to high-speed RAMmemory with our bank-select feature.

TRULY POWERFUL SOFTWARE

You have to have software. AndCromemco is far in front there, too.Our FORTRAN IV, for example, isequal to the FORTRAN compilerson large mainframes. Further, it (andour other software) is low-priced.

Our 16K Z80 BASIC is one of thefastest and most capable. Full 14-digit precision.

There's also our Z80 Macro As-sembler and Linking Loader. UsesZ80 mnemonics. Allows referencingFORTRAN common blocks.

CRT TERMINAL AND PRINTER

The CS-3 terminal has 80-characterlines and a 24-line page with lineand page editing.

Note the separate numeric keypadand cursor keypad.

The printer is fast—180 charactersper second; 132-column lines.

SEE AT YOUR DEALER

You have to see the CS-3 to fullyappreciate it and its low prices start-ing at $5990 in the rack mount ver-sion.

See it at your local dealer shownon the other side of this page. Hehas a demo to show you.

He also has brochures giving youdetails.

You know the CS-3 is going to bea sensation.

Better contact your dealer now.

Q

Cromemco

Circle 34 on inquiry card.

see next |\page \?

BYTE March 1978 1

MORE ABOUT THE SYSTEM THREE...

For office situations new SystemThree can be provided with walnutfloor cabinet. Metal bench cabinetalso available. Unit is normallyrack-mount style.

System Three front panel swingsopen and 21-slot motherboard/card cage slides forward for easyinsertion of extra circuit boards.

Retainer bar secures circuit cardsfirmly in sockets.

Optional panel PROM program-mer has two sockets to facilitateduplicating PROM content.

SEE YOUR LOCALSYSTEM THREE DEALER

PHOENIX, AZ

BYTE SHOP OF ARIZONA

24 West Camelback

•LITTLE ROCK, AR

COMPUTER PRODUCTS UNLTD.2412 So. Broadway

•CARSON, CA

SUNSHINE COMPUTER CO.20710 S. Leapwood Ave.

•CITRUS HEIGHTS, CABYTE SHOP OF SACRAMENTO6041 Greenback Ln.

•LOOMIS.CA

KINGMONT ENTERPRISES INC.9900 King Road

•SAN MATEO, CACOMPUTER TERMINAL309 So. San Mateo Drive

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RECREATIONAL COMPUTERS1324 South Mary

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COMPUTER COMPONENTS5848 Sepulveda Blvd.

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ATLANTA COMPUTER MART5091-B BufordHwy.

•HAIKU, MAUI, HICAPACITY, INC.P.O. Box A

•HONOLULU, HICOMPACT COMPUTERSP.O. Box 10096

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MICROCOMPUTER ENTERPRISES741 Kumakahi PI.

•SCHAUMBURG.ILDATA DOMAIN1612 E. Algonquin Road

•BLOOMINGTON, INDATA DOMAIN406 So. College Avenue

•FORT WAYNE, INDATA DOMAIN2805 E. State Blvd.

•PIKESVILLE, MDMODULAR SYSTEMS, INC.4005 Seven Mile Lane

•ROCKVILLE, MDCOMPUTER WORKSHOP1776 East lefferson

•BURLINGTON, MATHE COMPUTER STORE120 Cambridge Street

EDINA.MN

COMPUTER DEPOT3515 W. 70th St.

•ISELIN.NJ

COMPUTER MART OF NEW JERSEY501 Route #27

•EGGERTSVILLE, NYCORSON COMPUTER CORP.3834 Main Street

•HOLLIS, NY

SYNCHRO SOUND ENTERPRISES193-25 Jamaica Ave.

•CINCINNATI, OHDATA DOMAIN7694 Camargo Rd.

•DAYTON, OHDATA DOMAIN1932 Brown St.

•COLUMBIA, SC

BYTE SHOP OF COLUMBIA2018 Green Street

•NASHVILLE, TNSURYACORP.5755 Nolensvillc Rd.

CORPUS CHRISTI.TX

MICRO SYSTEMS SERVICES, INC.

5301 Everhart, Space H

•DALLAS, TXCOMPUSHOP211 Keystone Pk, 13933 North Central

•HOUSTON, TXELECTROTEX2300 Richmond Ave.

•HOUSTON, TX

MICROCOMPUTER ORIGIN STORE1853 Richmond Ave.

•MADISON, Wl

THE MADISON COMPUTER STORE1863 Monroe St.

HUNTINGDON, CAMBS, ENGLAND

COMART LTD

39 Gordon Rd.-Little Paxton

•WEDEL (HOLSTEIN), GERMANYDIGITRONIC COMPUTER SYSTEM GmbHBei der Doppeleiche 3-5

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Cromemco

Specialists in computers and peripherals

2400 CHARLESTON RO., FOUNTAIN VIEW, CA 94043 • (415) 964-7400

BYTE March 1978

Circle 34 on inquiry card.

In the Queue

BUI March 1978Volume 3 Number 3

84178185

8

18

56

74

114

152

166

168

174

186

Foreground

PROGRAM YOUR NEXT EROM IN BASIC

Memory—CiarciaINTERFACING THE SYKES OEM FLOPPY DISK KIT TO A COMPUTER

Hardware—HughesGET ON AT THE RIGHT ADDRESS

Hardware—Ho/man

Background

A TWO COMPUTER MUSIC SYSTEM

Music Hardware—Critchfield-Dwyer-LedererAN APPLE TO BYTE

Product Description—HelmersTHE MICROCOMPUTER AND THE PIPE ORGAN

Music Software—RaskinTHE BRAINS OF MEN AND MACHINES: How the Brain Analyzes Output

Robotics— KentUSER'S REPORT: THE PET 2001

Product Description—FylstraCIE NET: A DESIGN FOR A NETWORK

Personal Computing Networks—WilberMICROCHESS 1.5 VERSUS DARK HORSE

Chess—JenningsTAKE A COURSE IN MICROPROGRAMMING

Course Description—Mi/ianCONTROLLING THE REAL WORLD

Applica tions—OlsonTHE INTELLIGENT MEMORY BLOCK

System Design —Castleman

Nucleus

In "!"his BYTE

Don't Ignore the High End. . .or My Search for Manuscript Editing Paradise

Some Enticing Advance Words

Letters

BYTE's Bits

BYTE's Bugs

Book Reviews

Technical Forum: The Altair (S-100) Bus Forum: PCC 77

Programming Quickies

Clubs, Newsletters

4

6

6

14

27, 15146110148170172

194,204,214 What's New?222 Classified Ads

224 BOMB

224 Reader Service

BYTE is published monthly by BYTE Publications Inc. 70 Main St, Peterborough NH 03458. Address all mail except sub-scriptions to above address: phone (603) 924-7217. Address all editorial correspondence to the editor at the above address.Unacceptable manuscripts will be returned if accompanied by sufficient first class postage. Not responsible for lost manu-scripts or photos. Opinions expressed by the authors are not necessarily those of BYTE. Address all subscriptions, change ofaddress. Form 3579, and fulfillment complaints to BYTE Subscriptions, PO Box 590, Martinsville NJ 08836. Second classpostage paid at Peterborough NH 03458 and at additional mailing offices-USPS Publication No. 102410. Canadian secondclass registration No. 9321. Subscriptions are S15 for one year, $27 for two years, and $39 for three years in the USA and itspossessions. In Canada and Mexico, $17.50 for one year. S32 for two years, and $46.50 for three years. $25 for a one yearsubscription by surface mail worldwide. Air delivery to selected areas at additional rates available upon request. $25 for a oneyear subscription by air delivery to Europe. Single copy price is $2.00 in the USA and its possessions, $2.40 in Canada andMexico, $3.50 in Europe, and $4.00 elsewhere. Foreign subscriptions and sales should be remitted in United States funds.Printed in United States of America. Each separate contribution to this issue and the issue as a collective work copyright ©1978 by BYTE Publication Inc. All rights reserved.

PUBLISHER

Virginia Peschke Londner

EDITOR IN CHIEF

Carl T Helmers | r

PRODUCTION MANAGER

Jnclilh Havey

ADVERTISING DIRECTOR

Debra Boudrieau

CIRCULATION MANAGER

Gregory Spitzfadcn

EDITORS

Christopher P Morgan

Blaise W Liffick

CO-OP EDITORS

Raymond Cote

Scott Morrow

PRODUCTION EDITORS

Karen Gregory

David William Hayward

Nancy Salmon

ADVERTISING ASSISTANTS

Moreen Bardsley

Jill Callihan

Laura A Hanson

PRODUCTION ASSISTANT

Cheryl Hurd

CIRCULATION ASSISTANTS

Patricia Clark

Pamela R Heaslip

DEALER SALES

Ginnie F Boudricau

TRAFFIC MANAGERS

Thomas Harvey

EdmondC Kelly Jr

ART

Stephen Kruse

Wai Chiu Li

Dorothy Shamonsky

Ellen Shamonsky

RECEPTIONIST

Jacqueline Earnshaw

CLUBS AND NEWSLETTERS

David Wozmak

DRAFTING

Douglas Glen

Stephen Kruse

Lynn Malo

Bill Morcllo

TYPOGRAPHY

Goodway Graphics

PHOTOGRAPHY

Ed Crabtrcc

PRINTING

Rumford Press

NEW PRODUCTS EDITOR

Daniel Fylstra

ASSOCIATES

Walter Banks

Steve Ciarcia

David Fylstra

Portia Isaacson

BITS INC

Dennis Bliem

Floyd W Rehling

Jim Travisano

Ronald Wilzke

Jeremy Yousl

ADVERTISING SALES REPRESENTATIVES

EAST. MIDWEST

Hajar Associates Inc

17 Durant St

West Roxbury MA 02132

(617)325-5380

100 W Chicago AveChicago IL 60610(312)337-8008

WEST, SOUTHWESTBuckley/Boris Associates Inc912 South Barrington, Suite 202Los Angeles CA 90O49(213)826-4621

DISTRIBUTORSEASTERN CANADARS-232 Distribution Company186 Queen StW, Suite 232Toronto ONTARIO

WESTERN CANADAKitronic Ltd26236 26th Av RR 5AldergroveBC VOX 1A0

BYTE March 1978

About the Cover...

This month, Robert Tinney hascreated an oil painting on the theme of"Organs of Computers." Two articlesin this issue concern the prospect ofusing a personal computer system forthe editing and playing of music usingpipe organs under electronic control, aprospect which is emphasized by thetypical small system in place of theorganist. A grand pipe organ facadeand red carpet emphasize the regalnature of this king of instruments —with its new servant the small com-puter.

The Soloworks lab at the Universityof Pittsburgh has been conductingexperiments with computers for sometime. One of their areas of interestis computer music. Jeffrey Lederer,Tom Dwyer and Margot Critchfieldof that organization describe theirexperiments with pipe organs and anew high level music language calledMUSIC in A Two Compute MusicSystem. Page 8

The Apple II is one of several ex-amples of fully assembled "appliance"computers available coast to coast offthe shelf in computer stores. ReadAn Apple to Byte for a user's rea-sons to this product, and an exampleof a simple "color sketchpad" appli-cation implemented on the Apple II.

Page 18

In This EITI

If you don't know your Rauschep-feife from your Holtzregal, perhapsThe Microcomputer and the PipeOrgan by Jef Raskin can help. Thearticle introduces readers to pipe organtechnology and gives valuable adviceto the enterprising experimenter whowants to experiment with programmedpassacaglias on a Grossemischung.

Page 56

The study of biological neural com-puters is an important input tothought and design of robotic systems.This issue contains Ernest W Kent'sthird article in a series on The Brainsof Men and Machines. This install-ment, How the Brain Analyzes Input,gives essential background informationon the organization and operation ofsensory processing in the nervoussystems of mammals such as man.

Page 74

Would you like to do your ownEROM programming, but don't knowhow to begin? Read Steve Ciarcia'sProgram Your Next EROM in BASIC.You'll find an inexpensive circuit forprogramming and erasing these usefuldevices. Page 84

We have seen advance publicityand claims about the PET 2001 byCommodore for some time now.In this issue, Dan Fylstra reportson the realities of The PET 2001which arrived at his door October 111977. Page 714

In part 2 of his 3 part series onCIE Net: A Design for a Network ofCommunity Information Exchanges,

Mike Wilber presents the detailed pro-tocols designed for various types ofmessages between users and betweenintelligent nodes of the network itself.

Page 152

Readers of the January 1978 BYTEmay recall Dark Horse, one of thecomputer program contenders for theWorld Computer Chess Championship.This month, Peter Jennings' Micro-chess program makes a valiant effortto beat the favorite in Microchess 1.5versus Dark Horse. Page 166

Have you ever thought you mightlike to Take a Course in Micropro-gramming? Richard Mac Millan giveshis reactions upon taking such a coursefrom the Wintek Corporation. Hisinformation may help you decide ifthe course you think you might like totake is just what you had in mind.

Page 168

A really useful microcomputershould be able to control the environ-ment around it. To do this it must becapable of controlling electronic de-vices which are not TTL compatible.Hank Olson describes several ways ofdoing this in Controlling the RealWorld. Page 174

A mass storage system is essentialto the truly usable personal computer.One option for obtaining mass storageis presented in this issue by PhilHughes' article Interfacing the SykesOEM Floppy Disk Kit to a PersonalComputer. Page 178

With the cost of microprocessorsso low, the barriers to a multiprocessorcapability go down. Rather thanadding a memory region to yoursystem, why not consider the conceptof adding a combined memory andmicroprocessor subsystem. With anappropriate multiport memory regionand control logic, Ken R Castleman'sThe Intelligent Memory Block is a veryreal possibility for the homebrewerwith higher thruput as a goal. Page 186

BYTE March 1978

WAN

^s

««*

&VGIX:

\

-> DESCRIPTION:-

— Lower Case MNumeric Pad H Protect Node

^Tabbing J* Auto Repeat M15 Baud Rates

XDual Intensity MKux. Port — Addr. Cursor

*24 Line x 80 Char, -r Optional Printer Port & Block Mode

SOBOC IQ 120 is the most wanted terminal on the market

For information concerning the REWARD contact---

165 FREEDOM AVE., ANAHEIM.CA 92801(CHNOLOGY, INC. 714-392-3860 / 800-854-0147 M$\

Circle 11 2 on inquiry card.

BYTE March 1978 5

Editorial

Don't Ignore the High End

.or My Search for Manuscript Editing Paradise

by Carl Helmers

In this issue, we have included the firsttwo of four users' reviews of fully assembledand tested self-contained computers. Theselection criterion is that the "typical user"(in two cases Dan Fylstra, one case DennisBarbour, and one case myself) was able topurchase an off-the-shelf computer of thelow end "appliance" variety. These machinesrepresent a significant technological achieve-ment in the form of a fairly inexpensivecomputer with a high level language (BASIC)and limited mass storage facility in the formof audio or modified audio cassette tape. Intheir class of price and performance circaDecember 1 1977, these "appliance" com-puters represent perhaps the ultimate wehave seen to date.

As time goes on, I'll update the ultimate,but that is not my purpose in this essay.

There is a utilitarian class of personal com-puter products which I have used most inmy homebrew system. I refer of course tothe high end of performance in small com-puter systems, the system with perhaps 16 Kto 32 K memory, single or dual full sizefloppy disks, terminal device, and all theaccoutrements of what we used to know as"minicomputers" but now within the pricerange of the family that can afford an $8000car. My attention was turned to this classof machine recently when I began shoppingaround for some equipment and softwareto automate several aspects of the manu-script preparation process which I and myassociates in the editorial department per-form daily at BYTE.

Continued on page 136

Some Enticing Advance Words

Photo 7.

Turtles are coming. In mid November1977, Dan Hillis of the LOGO project atMassachusetts Institute of Technology calledBYTE and posed one of those questionswhich have only one answer. "Would readersof BYTE magazine be interested in aninexpensive kit version of the famous LOGOproject turtle robots?" Dan outlined on thephone the idea of a kit with a target price of$250, and suggested that I take a trip to theMIT Al (artificial intelligence) Laboratoryto take a look at his prototypes. I wasdelighted to accept the invitation, whichincluded a heady tour of some of the pro-jects at the Al laboratory and the Archi-

tecture Machine project's advanced colorvideo display technology.

The turtle is not yet ready for market,but it is getting close, as can be seen byphoto 1 which I took while lying prone onthe floor of the laboratory as Dan put theprototype through its paces. The idea is toproduce a rugged and childproof motionoutput device with tail drag plotting capa-bilities provided by a ball point pen con-trolled by solenoid. In the past turtle robotshave proved to be excellent devices forteaching children programming concepts,both in simulations on screens, and asmechanically mobile output peripherals.The intent is to make the new turtle pro-duct virtually indestructible with Lexanplastic housing and wheels, and ruggedmechanical and electronic innards. Dandemonstrated some of this indestructibilitywith a prototype sans housing by droppingit from a height of about two meters ontothe carpeted floor of the laboratory.

Of course a turtle is not all hardware, soversions of the LOGO language adaptedto personal computer architectures will berequired. Dan and his associates (all quiteyoung) at MIT have formed a companywhich intends to introduce turtles muchmore formally sometime in early 1978.We'll expect to keep readers informed ofthis exciting prospect as it develops andgets closer to production."

BYTE March 1978

I

THE EQUINOX SYSTEM

en you put it together, it's really together. I

Some people build personal computers for the love of building. The Equinox Systemis for people who build for the love of computing.You put it together. And it's really together.

ming station featuring ultra-convenient octal keyboard and dfgital LED readout.

There are low-cost 4K and 8K memories. All your interfacing comes in one kit. EvenEQU/ATE™and BASIC-EQ™ languages on easy-loading cassettes.

It's all together now. It's all S-100 compatible. And it's upward-compatible with newEquinox™equipment, software and systems coming in the months ahead.

See the Equinox System™ at your local computer shop. Call toll-free to 800-648-5311(BAC/MC accepted). Or write Equina* .Division. Parasitic Engineering, P.O. Box 6314,Albany, California 94706. THE E0WINO3WSTEM™ All together now.

Circle 90 on i

tf •■**<

A Two Computer Music System

Photo 1: The authors' overall system with graphics terminal on the left andthe disk drive and two computers on top of the organ console. The woodenpipes at top right are the flute rank; the metal pipes are a viola rank. The stoptablets for selecting ranks and harmonics can be seen just above the topkeyboard.

The music system described here startedout a few years ago as a project in theSoloworks Lab. The idea was to put togethera "manipulable" system that allowed stu-dents to work with the powerful mathemati-cal idea of synthesis. We felt that mathematicsand science students should be able toexperience firsthand what could be done bysuperimposing components that workedtogether to synthesize some bigger concept.

Real, full-blown professional musicseemed like an ideal metaphor for workingwith this "superimposition" principle. It'seasy for a student to see that a musicalperformance is really a multitude of small,discrete events working in perfect synchro-nism. But it's even easier to sense that theresultant whole is greater than the sum ofits parts. In fact, the "whole" can be ahuman experience of quite thrilling pro-portions.

The system that evolved has met this goalvery well. Students of varied backgroundsare able (and motivated) to work patientlywith complex scores, making the final per-formance a proof of the power of the princi-ple of superimposition.

But a funny thing happened on the wayto this goal. The total system began to lookmore and more like a "micro" computerscience curriculum. The documentation thatevolved began to contain much of the jargonthat permeates computing, but this seemedto be easier to take when interpreted in termsof the friendlier worlds of music and art.

In writing this condensed description ofthe system, we therefore decided to leavethe jargon in. Our purpose is to not onlydescribe the music system but to suggestthat interesting new approaches to teachingcomputer science might be developed alongsimilar lines. There is equally good promisefor teaching computer science subject matterin terms of visual art. Abstract games areanother fruitful area. It's probably no coinci-dence that all these examples illustrate thekind of computing most people would call"fun." There's undoubtedly a deep educa-tional lesson lurking here, but that's anothersubject.

BYTE March 1978

Why a Pipe Organ?

The system described here is generalenough to apply to a variety of musicalinstruments. It was implemented with asmall pipe organ because this illustratesthe general kind of performance ensembleused by composers who write orchestralworks. A pipe organ has several sets of pipescalled ranks, each set having a distinctivetonal characteristic called timbre. The ranksare selected by pressing switches called stoptablets, so that an organist is able to controlan entire "orchestra" of sounds by usingdifferent stop settings. Further, since mostpipe organs have several keyboards (oftenincluding one for the feet), the ranks can beplayed independently. Thus both chorded(several notes played simultaneously) andcontrapuntal (independent melody linesplayed simultaneously) music can be playedon one or more keyboards.

The organ is also the original "syntheticmusic" instrument. This is because a per-former can add harmonics to fundamentaltones by pressing suitable stop tablets. Whenthe stop tablet marked "8 foot flute" ispressed, one gets flutelike sounds, in thenormal register (where A=440 Hz). (Thephrase "8 foot" comes from the fact thatthe largest pipe in the rank is eight feet high.)But when the stop marked "4 foot flute" ispressed, everything sounds an octave higher.If both stops are activated, we then havea sound rich in second harmonics. Tradi-tional organs have stops labeled "8 foot,""4 foot," "2 2/3 foot," "2 foot," etc.However, the stop settings in the computersystem described here are software generated,so any harmonic can be specified (of coursethere are only a finite number of pipesavailable for playing these harmonics).

Overview of the System

The Music System uses two microcompu-ters (an Altair 8800b system and an Intellec8/MOD 80), a small pipe organ, and aMagnavox plasma display graphics terminal.Figure 1 shows how these components areinterconnected.

In addition to the hardware, there arethree software packages. The first is agraphics music editor that allows a com-poser to "draw" his score on a graphicsdisplay terminal. The editor converts thegraphic representation of the score intoa MUSIC language program. The programmay also be created and edited using a stan-dard text editor, in which case an alphanu-meric terminal can be used. Either type ofeditor is run on the master system. TheMUSIC language programs can be saved on adiskette as files.

Before a MUSIC language program can beplayed, it must be "compiled." Our compileris a program that accepts MUSIC languageprograms as input, and outputs an annotatedlisting of the MUSIC language program alongwith error messages and an "object" pro-gram . The object program consists of instruc-

10TERMINALS

MASTER COMPUTER(ALTAIR 8800)

CURRENT LOOPINTERFACE

SLAVE COMPUTER(INTELLEC 8)

128 TTLOUTPUTS

TTL TO POWER INTERFACE

Jeffrey H Lederer

Tom Dwyer

Margot Critchfield

Project Solo

University of Pittsburgh

Pittsburgh PA 15260

DISKETTESTORAGE

Q00Q0QQQ

PIPE (OR KEYBOARD)SOLENOIDS

Figure I: Hardware components of the authors' computerized organ musicsystem. This design requires one TTL output line for each pipe to becontrolled.

BYTE March 1978

9

GRAPHICSTERMINAL

Figure 2: Software blockdiagram of the computerorgan music system.

COMPOSER

MUSICLANGUAGESOURCEFILE

OBJECTFILE

MASTER

PERFORMANCE

PROGRAM

_L_

SLAVE

PERFORMANCE

PROGRAM

PIPEORGAN

ALPHANUMERICTERMINAL

SOURCELISTINGWITH ERRORMESSAGES

2400 BPS LINE

Photo 2: A set of solenoids used to automaticallyplay the keys. Since this setup plays the keys directly,it could be easily adapted to any standard keyboardinstrument including harpsichord and piano.

tions which are easily interpreted by theslave computer. The compiler runs on themaster computer.

The object program is "played" usingboth computers. First, the object programis transferred from the master to the slavecomputer. The slave computer executesthe object program in order to drive thepipe organ. A pair of programs (one oneach computer) controls the transfer ofthe object program and its execution.Figure 2 shows the relationship betweensoftware components.

System Hardware

The slave microcomputer is an Intellec8/MOD 80 with 8 K bytes of programmablememory, 2 K bytes of read only memorycontaining a system monitor program,256 bytes of programmable read onlymemory that contains the second perfor-mance program, 16 latching output ports,and a serial bidirectional IO port. Eachlatching port is eight bits wide, with eachbit dedicated, to controlling a pipe valveof the organ. Thus, 16 X 8 = 128 pipescan be controlled. The interface betweeneach pipe and its controlling port is a Darling-ton switching transistor connected as shownin figure 3.

The master computer is an Altair 8800bwith 60 K bytes of memory, two diskettedrives and two serial ports. One serial portis used as the console line and is connectedto a Magnavox plasma graphics terminal.This terminal has a plasma display with 512by 512 dots. A character generator is used todisplay 32 lines of 64 characters; the charac-ters can be either a set of standard ASCIIcharacters or a user loaded set (musicalsymbols in our case). The terminal has avector generator and dot addressability.Sections of the screen can be selectivelyerased and written. The graphics terminalis optional, and there is no reason whyother lower cost graphics displays couldn'tbe used if appropriate changes in softwarewere made. The Intecolor 8001 might beparticularly appropriate since different colorscould be used to distinguish voices in poly-phonic music.

The second serial line connects the Altairto the Intellec over a 2400 bps current loop.A special interface had to be built to isolatethe two active current loops. The schematicis shown in figure 4.

10

BYTE March 1978

TARBELL SETS STANDARDS

For Hobbyists and Systems Developers

Sales to thousands of hobbyists over the past two years have proven the Tarbell CassetteInterface to be a microcomputer industry standard. Tarbell Electronics continues research anddevelopment to produce new and efficient components to fill hobbyists' changing needs.

TARBELLCASSETTE INTERFACE

• Plugs directly into your IMSAI or ALTAIR*

• Fastest transfer rate: 187 (standard) to 540 bytes/second

• Extremely Reliable—Phase encoded (self-clocking)

• 4 Extra Status Lines, 4 Extra Control Lines

• 37-page manual included

• Device Code Selectable by DIP-switch

• Capable of Generating Kansas City tapes also

• No modification required on audio cassette recorder

• Complete kit $120, Assembled $175, Manual $4

TARBELL FLOPPY DISC INTERFACE

• Plugs directly into your IMSAI orALTAIR* and handles up to 4standard single drives in daisy-chain.

• Operates at standard 250K bitsper second on normal disc formatcapacity of 243K bytes.

• Works with modified CP/MOperating System and BASIC-ECompiler.

• Hardware includes 4 extra ICslots, built-in phantom bootstrapand on-board crystal clock. UsesWD 1771 LSI Chip.

• 6-month warranty and extensivedocumentation. ^ ... , _.. _ ,

• PRICE Compatible Disc Drives

Kit $190 Assembled $265 Ask about our disc drives priced as low as $525.

For fast, off the shelf delivery, all Tarbell Electronics products may be purchased from computer store dealersacross the country. Or write Tarbell Electronics direct for complete information.

'ALTAIR is a trademark/tradename of M1TS, Inc.

C-J f&M/Jf// A 2°62° Soutn Leopwood Avenue, Suite Pr\tj^^^^y Carson, California 90746

:roncs <2i3> 538-4251

Circle 121 on inquiry card. byte March 1978 11

H2VDC

MANUALKEY

SOLENOID

COIL

IN PIPE

MJ IOOO

JT

^-"»

FROM

, . INTELLEC

<_]TTL

OUTPUTPORT

Figure 3: Interface between an organ pipe solenoid and a computer outputbit. One such circuit is needed for each pipe to be controlled in this design.The solenoid in each pipe opens a valve that admits air to the pipe.

4N28

-o

CURRENTLOOP OUT

■o

Figure 4: Interface used to isolate the two 2400 bps active current loopswhich send information back and forth between the master and slavecomputers.

MUSIC Language

MUSIC is a high level music notationlanguage that uses the standard 64 charac-ter'ASCII character set. A MUSIC languageprogram consists of one or more statements;each statement is a single line in length (seefigure 5 and listing 1).

There are three types of statements inthis language: command, data, and commentstatements. Comment statements, whichbegin with two asterisks, may be placedanywhere in the program; they are ignoredby the compiler.

The command statements consist of asingle asterisk followed by the commandmnemonic and the command's parameters.The commands in this language are dividedinto three categories: delimiter commands,repeat commands, and context commands.

The delimiter commands separate mea-sures (BAR), parts of measures (CHANGE),and mark the end of the last measure of theprogram (END). The parameters of the firsttwo commands, when used, set a temporarytime signature for a measure.

The repeat commands control the repeti-tion of sections of the score. The limits ofa repeated section are bracketed by HEADand TAIL commands. When necessary, eachseparate ending of a repeated section starts

with an ENDING command, and sections ofa score between SIGN commands can beskipped the second time through a repeatedsection. Repeated sections can be nestedwithin each other.

The context commands are used tochange the condition under which the notesof the program are compiled. These com-mands set the key signature (KEY), timesignature (TIME) and metronome settingwith or without accelerandos and ritards(TEMPO). A special context command(STOPS) controls the number of voicesallowed in each measure and the stop(timbre) settings for each voice.

The notes for a MUSIC language programare placed in the data statements. Each datastatement consists of one or more events;each event is separated from the previousevent by a semicolon. An event is a note,chord, glissando, tremolo or rest. The notescan be played with different articulations(staccato, legato, or normal). [See theglossary at the end of this article.] Each datastatement contains the events to be per-formed by one voice during a single measureor fraction of a measure.

A normal measure of music consists ofa starting BAR command followed by zeroor more context commands and one datastatement for each active voice. When acontext change occurs inside a measure,the form of that measure is slightly different.In this case the measure starts with a BARcommand, zero or more context commandsand one data statement for each voice. Thesedata statements contain those events thatoccur before the context change. Followingthe data statements is a CHANGE command,one or more context commands and onedata statement for each voice. These latterdata statements contain the events thatoccur after the context change. Repeatcommands may be intermixed with thecontext commands of a measure.

The voices in each measure are performedconcurrently. Each voice is assigned a groupof stop settings. Each stop setting takes anote, displaces it a set amount of tones,and assigns that new pitch to a given rankof pipes. Multiple stop settings for a voicewill generate multiple pitches for each notein an event. These pitches are played simul-taneously. The number of voices and theirstop settings are controlled by the STOPScommand.

This all sounds pretty complicated, butnew users quickly get proficient with thelanguage. Having all the features of musicalnotation available has proven to be well worththe extra complexity.

Continued on page 48

12

BYTE March 1978

^our experiencewith personal computers

is going to openan unlimited career at TL

TI is into personal computersin a big way, and that means aground floor opportunity isgoing to be open for you, thepersonal computing innovator.You'll be joining the undis-puted world leader in creatingnew products and markets forconsumer electronics with thecompany that invented thecalculator on a chip. And it's allgoing to happen in TI's newManagement and TechnologyCenter for Consumer Productsin Lubbock, Texas. Located inthe high, dry, and cool plainsof West Texas, Lubbock isabout halfway between Dallasand Albuquerque. It is thehome of Texas Tech University.You are just a few hours' drivefrom skiing in Taos, or touringand shopping in Juarez,Mexico.

Make your career opportuni-ties in the following areas:

Personal ComputerProduct Marketing Manager

Responsible for establishingdistribution channels forpersonal computer products,developing advertising andsales promotion programs,training, quoting and providingmarket requirements for newproducts and software.Requires BS in EE, math,physics or Computer Science.MBA preferred. Minimum of5 years' experience in con-sumer sales or marketingrelated to desk programmablecalculators, minicomputer

systems, microcomputersystems, or small businesssystems.

Systems Programmers

Outstanding opportunities —design, code, integrate anddebug operating systemmodules, including deviceservice routines, self-testdiagnostics, and system utili-ties. Requires BSEE or Com-puter Science plus minimum of3 years in assembly program-ming with some high levellanguage experience.

Digital Design Engineers

Opportunity to design anddevelop digital subsystems formajor new products. Projectswill require design-to-costdiscipline with internal andexternal component vendors,vendors of peripheral devicesand making trade-offs of hard-ware and software. RequiresBSEE with 2 years' experience.Prefer experience in design ofbubble and/or flexible diskcomputer memory subsystems.

Product Design Engineer

Responsibility for mechani-cal design on major new per-sonal computer products.Interface with electrical designengineers, software develop-ment personnel, marketing,purchasing, planning and allareas involved in taking aproduct from concept throughinitial production. RequiresBSME with a minimum of

3 years' experience in designor closely related field.Knowledge of plastic toolingpreferred.

Application Software Specialist

Total responsibility fordevelopment of complete appli-cation packages for specificbusiness sectors and profes-sionals. Specifications, design,coding, program check-out anddocumentation for personalcomputer systems. RequiresBA or BS in math or ComputerScience or BBA with data pro-cessing major with 2-3 years'experience. Program in highlevel language on mini, micro,or business computer systems.

Marketing Support Engineers

Project responsibility forfuture product service directionconcerning existing as well asfuture products. Develop andmaintain total service programfor personal computer systemsand field testing/check-out.Requires BSEE or equivalentwith at least 3 years' experi-ence with programmable deskcalculators, minicomputer sys-tems, microcomputer systems,small business systems,or product servicemanagement. , 1 o

Send your resume inconfidence to: Bill Toomey/P. O. Box 10508, M.S. 5807,Dept. B / Lubbock, TX 79408.

Circle 126 on inquiry card.

Texas Instruments

INCORPORATED

An equal opportunity employer M/F

BYTE March 1978

13

NETWORKING WITH TELEPHONES?

Dave Caulkins' Personal ComputerNetwork (PCNET), in September 1977BYTE, sounds like a great idea, for thosewho live in the Palo Alto CA area; butuntil PCNET goes national or semi-national there is a method available (on asmaller scale) to computer users rightnow: Northwestern Bell's Direct DialConferencing. Using DDC, up to sixcomputers can exchange data usingstandard Touch-Tone telephones andmodems. For complete instructionsand to see if DDC is available in yourarea contact your local NorthwesternBell business office. There is only oneproblem with using DDC, it costs $.50per minute. That can add up to quite alot in a short amount of time, if you'renot careful!

Another way to do the same thing ata fraction of the cost is by using anothergadget that Ma Bell provides, Three WayCalling. You can get Three Way Calling(if it's available in your area) simply byasking for it and paying about $2.50 permonth additional on your phone bill.With Three Way Calling you and twofriends can exchange data without acostly per minute charge. The number ofcomputers you can interface togethermight be increased by the use of ThreeWay Calling by more than one of thepersons involved. I have not had theopportunity to try this, so I can'tguarantee anything. Perhaps there is nolimit to how far you can go.

Steve Hughes

4410 Douglas Av S

Golden Valley MN 55416

BACKLIGHTING VIA PHOTOCOPY

With all of the comments that I haveseen about the advantages of using back-lighting for reading PAPERBYTES, itis rather suprising that I have not seenthe following suggestion for accom-plishing it without wasting magazinespace: let those readers who wish to usethe backlighting method photocopy theappropriate pages. The photocopiescould then be read by backlighting asthey would only be printed on one side.Obviously, though, the photocopieswould have to be of the highest quality.From what I have seen of the coin oper-ated machines and home type machines,they would not be of sufficient quality,

but that obtained at copying centersprobably would be.

I will admit that I have not tried thisidea, primarily because my system is notyet operational. However, I think it isan idea well worth trying.

Clark Jones

225 Pennsylvania NE Apt H

Albuquerque NM 87108

Fred Merkowitz of Micro-ScanAssociates, Natick MA, reports that hisfront side scanner works just fine withphotocopies of bar codes, sometimestried through several generations ofrecopying just to see what would hap-pen. Backlighting is just not needed withan appropriate scanner.

COMMENTS ON PROGRAMMINGAND DESIGN STYLE

I would like to thank David AHiggins for his article "Structured Pro-gram Design" (October 1977 BYTE,page 146); however, I found that hispresentation lacked clarity. There area large number of reasons why "top-down" structured programming becamepopular. I feel that Mr Higgins has mis-applied his design technique, in thesame way he feels top-down program-ming was misapplied to design.

The Warnier-Orr diagrams approachto design should, I feel, be followed(and augmented) by the top-downapproach to programming. What happenswhen a design technique is applieddirectly to coding is shown clearly byMr Higgins' own programming example!He claims that the resultant code is easyto read and understand. I stipulate thatthis is only true if the programmerworking on it has the original Warnier-Orr diagram it was coded from. Thissame argument applies to his next twopoints as well. A program is easy tochange and maintain only if the programlogic flow is immediately evident. If wewere to draw lines between all of MrHiggins' GOSUBs and their destinations,we would end up with another bowl ofcold spaghetti! Again, the documen-tation he has consists mainly of a titleremark at the head of each subroutine,which serves only to relate each sub-routine to a bracket in the Warnier-Orrdiagram.

Continued on page 128

\bur

Sol dealer

has it.

AZ: Tempe: Byte Shop, 813 N. Scottsdale.(602)894-1129; Phoenix: E}yte Shop, 12654 N.28th, (602)942-7300; Tucson: Byte Shop. 2612E, Broadway, (602)327-4579. CA: Berkeley:Byte Shop, 1514 University, (415)845-6366; CitrusHeights: Byte Shop, 6041 Greenback, (916)961-2983; Costa Mesa: Computer Center. 1913Harbor, (714)646-0221; Hayward: ByteShop, 1122 "B" St., (415)537-2983; Lawndale:Byte Shop. 16508 Hawthorne, (213)371-2421;Orange: Computer Mart, 633-B W. Katella, (714)633-1222; Pasadena: Byte Shop, 496 S. Lake,(213)684-3311; Sacramento: Micro-ComputerApplication Systems, 2322 Capitol, (916)443-4944; San Francisco: Byte Shop, 321 Pacific,(415)421-8686; San Jose: Byte Shop, 2626Union, (408)377-4685; San Rafael: Byte Shop,509 Francisco, (415)457-9311; Tarzana: ByteShop, 18423 Ventura, (213)343-3919; WalnutCreek: Byte Shop. 2989 N. Main, (415)933-6252.CO: Boulder: Byte Shop, 3101 Walnut. (303)449-6233. FL: Ft. Lauderdale: Byte Shop. 1044E. Oakland Pk., (305)561-2983; Miami: ByteShop, 7825 Bird, (305)264-2983; Tampa:Microcomputer Systems, 144 So. Dale Mabry,(813)879-4301. GA: Atlanta: Computer Mart,5091-B Buford, (404)455-0647. IL:Champaign:Computer Co., 318 N. Neil, (217)359-5883;Numbers Racket. 62314 S. Wright, (217)352-5435;Evanston: itty bitty machine co. 1322 Chicago,(312)328-6800; Lombard: itty bitty machine co,42 W. Roosevelt, (312)620-5808. IN:Bloomington: Data Domain, 406S. College, (812)334-3607; Indianapolis: Data Domain, 7027N. Michigan, (317)251-3139. IA: Davenport:Computer Store, 4128 Brady, (319)386-3330.KY: Louisville: Data Domain, 3028 Hunsinger,(502)456-5242. Ml: Ann Arbor: ComputerStore, 310 E. Washington, (313)995-7616; Troy:General Computer Store, 2011 Livernois, (313)362-0022. MN: Minneapolis: Computer Depot,3515 W 70th, (612)927-5601. NJ: Hoboken:Computer Works, 20 Hudson PL, (201)420-1644;Iselin: Computer Mart, 501 Rt. 27, (201 )283-0600.NY: New York: Computer Mart, 118 Madison,(212)686-7923; White Plains: Computer Corner.200 Hamilton, (914)949-3282. NC: Raleigh:ROMs 'N' RAMs, Crabtree Valley Mall. (919)781-0003. OH: Columbus: Byte Shop, 2432Chester. (614)486-7761; Dayton: ComputerMart, 2665 S. Dixie, (513)296-1248. OR:Beaverton: Byte Shop, 3482 SW Cedar Hills,(503)644-2686; Eugene: Real Oregon ComputerCo., 205 W. 10th, (503)484-1040; Portland:Byte Shop, 2033 SW 4th Ave., (503)223-3496.Rl: Warwick: Computer Power, M24 Airport Mall,1800 Post Rd„ (401)738-4477. SC: Columbia:Byte Shop, 2018 Green, (803)771-7824. TN:Kingsport: Microproducts & Systems. 2307 E.Center, (615)245-8081. TX: Arlington:Computer Port, 926 N. Collins. (817)469-1502;Houston: Computertex, 2300 Richmond,(713)526-3456; Interactive Computers, 7646'/2Dashwood, (713)772-5257; Lubbock:Neighborhood Computer Store. 4902-34th St.,(806)797-1468; Richardson: Micro Store.634 So. Central Expwy., (214)231-1096. VA:McLean: Computer Systems Store, 1984Chain Bridge, (703)821-8333; Virginia Beach:Home Computer Center, 2927 Va. BeachBlvd., (804)340-1977. WA: Bellevue: Byte Shop,14701 NE 20th, (206)746-0651; Seattle: RetailComputer Store, 410 NE 72nd. (206)524-4101.Wl: Madison: Computer Store, 1863 Monroe,(608)255-5552; Milwaukee: Computer Store,6916 W North, (414)259-9140. D.C.:Georgetown Computer Store, 3286 M St. NW(203)362-2127. CANADA: Ottawa, Ont:Trintronics, 160 Elgin, (613)236-7767; Toronto,Ont: Computer Mart, 1543 Bayview. (416)484-9708; First Canadian Computer Store, 44Eglinton Ave. W, (416)482-8080; ComputerPlace, 186 Queen St. W.. (416)598-0262;Vancouver, B.C.: Basic Computer Group. 1438E. 8th, (604)736-7474; Pacific ComputerStore. 4509 Rupert, (604)438-3282.

Processor

14

BYTE March 1978

Circle 98 on inquiry card.

Seven points

to consider

before

you buy your

small computer.

In this magazine, alone, there are probably a dozenads for small computers. New companies are breakingground like spring flowers.

How, then, do you determine which computer offers thefeatures you need most... at the price you can afford?

We'd like to propose seven basic questions to help youmake an intelligent decision.

IHow complete is thecomputer system?W Many buyers of small computers are in for a rudeawakening when they have to spend additional moneyfor interfaces.

The Sol-20 Terminal Computer was the first completesmall computer system. Everything you need to makeit work is included in the basic package.

2 Is powerful systemsoftware available?W It won't do if your system is "tongue-tied'.'Processor Technology Corporation has devotedmore effort to the development of software than any othersmall computer maker. Our latest offering is the firstfully implemented disk operating system for a smallcomputer: PTDOS. It contains over 40 major commands,several languages and numerous utilities. Our highlevel languages include Extended BASIC, Assembler,FORTRANf FOCAL and PILOT*

3 Is the system easyto expand?W More and more computer owners areexpanding their small computers to handle business andother specialized requirements.

The largest Sol system can handle 64K bytes of RAMmemory and operate with a three megabyte on-linedisk memory. Sol systems use the S-100 Bus. So you canuse a wide variety of hardware.

'Available soon.

Circle 98 on inquiry card.

Processor

4 Is the computerwell-engineered?W Our Sol systems are the most conservativelyrated and ruggedly built in the industry, period. Inaddition we designed them with you, the user, in mind;Sols are easy to build and a joy to operate.

5 Does it have provenreliability?W What is the track record? There are over5,000 Sol systems in the field. Our track record for reliableperformance is unparalleled in the small computer field.

6

Does it have goodfactory support?

A computer is a complex piece of hardware.So you want to be sure it is backed up with completemanuals, drawings and a factory support team that cares.

Processor Technology offers the most extensivedocumentation of any small computer manufacturer. Andwe maintain a patient, competent telephone staff toanswer your questions.

7 Are maintenance andservice people accessible?Where are they located?Processor Technology has maintenance and servicepeople in over 50 cities around the U.S.

As you continue turning the pages, see how we stack upto the other computers in this magazine. If we'vesucceeded in whetting your appetite, see your Sol dealeror write for information on the complete family ofSol computers.

Processor Technology Corporation, Box B,7100 Johnson Industrial Drive, Pleasanton, CA 94566.(415) 829-2600.

Diogy

BYTE March 1978

15

Introducing Apple II.

t

mM-HBO******"

The home computer that s readyto work, play and grow with you.

Clear the kitchen table. Bring in the colorT.V. Plug in your new Apple Hf and connectany standard cassette recorder/player. Nowyou're ready for an evening of discovery inthe new world of personal computers.

Only Apple II makes it that easy. It's acomplete, ready to use computer—not a kit.At $1298, it includes features you won't findon other personal computers costing twice as

much.

Features such as video graphics in 15 colors.And a built-in memory capacity of 8K bytesROM and 4K bytes RAM -with room for lotsmore. But you don't even need to know aRAM from a ROM to use and enjoy Apple II.It's the first personal computer with a fastversion of BASIC—the English-like pro-gramming language—permanently built in.That means you can begin running yourApple II the first evening, entering your owninstructions and watching them work, even ifyou've had no previous computer experience.

The familiar typewriter-style keyboardmakes communication easy. And your pro-grams and data can be stored on (and re-trieved from) audio cassettes, using the built-in cassette interface, so you can swap withother Apple II users.This and other peri-pherals—optional equipment on most per-sonal computers, at hundreds of dollars extracost—are built into Apple II. And it'sdesigned to keep up with changing technol-ogy, to expand easily whenever you need it to.

As an educational tool, Apple II is a soundinvestment.You can program it to tutor yourchildren in mostany subject, such

history or math. But the biggest benefit—nomatter how you use Apple II—is that you andyour family increase your familiarity with thecomputer itself. The more you experimentwith it, the more you discover about itspotential.

Start by playing PONG. Then invent yourown games using the input keyboard, gamepaddles and built-in speaker. As you experi-ment you'll acquire new programming skillswhich will open up new ways to use yourApple II. You'll learn to "paint" dazzling colordisplays using the unique color graphics com-mands in Apple BASIC, and write programsto create beautiful kaleidoscopic designs.As you master Apple BASIC, you'llbe able to organize, index andstore data on household fi-nances, income tax,recipes, and record col-lections. You can learn tochart your biorhythms,balance your checking ac-count, even control your homeenvironment. Apple II will go asfar as your imagination can take it.Best of all, Apple II is designed to growwith you. As your skill and experience withcomputing increase, you may want to addnew Apple peripherals. For example, a re-fined, more sophisticated BASIC language isbeing developed for advanced scientific and

mathematicalapplications.And in addi-tion to thebuilt-inaudio, videoand gameinterfaces,there'sroom foreight plug-inoptions such as a prototyping board for ex-perimenting with interfaces to other equip-ment; a serial board for connecting teletype,printer and other terminals; a parallel inter-face for communicating with a printer oranother computer; an EPROM board for stor-ing programs permanently; and a modemboard communications interface, or a floppydisk interface with software and completeoperating system. And there are many moreoptions to come, because Apple II wasdesigned from the beginning to accommo-date increased power and capability as yourrequirements change.

If you'd like to see for yourselfhow easy it is to use and enjoyApple II, visit your local dealer for ademonstration and a copy of ourdetailed brochure. Or write Apple

Apple II™ is a completely self-containedcomputer system with BASIC in ROM,color graphics, ASCII keyboard, light-weight, efficient switching power supplyand molded case. It is supplied withBASIC in ROM, up to 48K bytes ofRAM, and with cassette tape, video andgame I/O interfaces built-in. Also in-cluded are two game paddles and ademonstration cassette.

SPECIFICATIONS

• Microprocessor: 6502 (1 MHz).

• Video Display: Memory mapped, 5

modes—all Software-selectable:

• Text—40 characters/line, 24 linesupper case.

• Color graphics—40h x 48v, 15 colors

• High-resolution graphics—280hx192v; black, white, violet, green(16K RAM minimum required)

• Both graphics modes can be selectedto include 4 lines of text at the bottomof the display area.

• Completely transparent memoryaccess. All color generation donedigitally.

• Memory: up to 48K bytes on-boardRAM (4K supplied)

• Uses either 4K or new 16K dynamicmemory chips

• Up to 12K ROM (8K supplied)

• Software

■ Fast extended Integer BASIC inROM with color graphics commands

■ Extensive monitor in ROM•I/O

• 1500 bps cassette interface

• 8-slot motherboard

■ Apple game I/O connector

• ASCII keyboard po_rt_

• Speaker

• Compositevideooutput j

Apple II is also ^R

available in board-onlyform for the do-it-yourself hobbyist. Hasall of the features of the Apple II system,but does not include case, keyboard,power supply or game paddles. $798.

PONG is a trademark of Atari Inc.*Apple II plugs into any standard TV usingan inexpensive modulator (not supplied).

Computer Inc., 20863 Stevens Creek Blvd.,Cupertino, California 95014.FULL PAGE DEALER AD ON PAGE 119.

tipple computer inc.

Circle 5 on inquiry card.

Ml -

1

^HHHHIHI

IB

MMfT MM COLOHn

An Apple to Byte

Carl Helmers, Editor

It has been a little over a year sinceI first became aware of the prototype ofthe Apple II computer on a visit to PaloAlto CA in November of 1976. At the timeI first viewed the Apple II prototype, itwas little more than a wire wrapped proofof concept in a homebrew masonite box.In the year since my first exposure to themachine Apple II has become what I con-sider to be one of the best examples of theconcept of the complete "appliance" com-puter. This variety of computer is sold asa finished product off the shelves of theretailer's shop or by mail from the manu-facturer's warehouse. In late October of1977, I took delivery on an Apple II with16 K bytes of programmable user memory.After removing it from its shipping box,I connected it to a color television withthe cables and radio frequency modulatorsupplied, and also connected it to an inex-pensive tape recorder with an "index"counter to keep track of position. I wasable to turn on power and begin using thecomputer within five minutes of receipt.After one session in my basement labora-

Photo 7: A concoction of color resembling abyrd. This color doodle was produced usinga homebrew joystick plugged into the AppleII's game 10 connector, and a BASICprogram to implement interactive drawingon the television screen. The photograph wasmade using I/75th second exposure andASA 200 Kodachrome slide film in a 35mmcamera with macro lens mounted on atripod. All the color photographs in thisarticle were taken using this setup.

tory wiring up some joystick hardwareusing Apple II's documentation as a guide,and after about three evenings of hackingwith the built-in ROM BASIC interpreter,I was able to produce a program for a colorsketchpad to provide an illustration ofsome of the potentials of such small com-puters for use in artistic contexts. WhileI treat the Apple II as one of the neatest"proofs of concept" of the idea of thepersonal computer yet to become avail-able, it is by no means the only one on themarket, so readers should judge for them-selves with respect to their own values andpreferences.

The potential for producing graphics likephoto 1 illustrates why I became intoxi-cated with the Apple II concept from thefirst word of its existence. With a personalinterest in the uses of computers for artistic

One User's Review of the Apple II

18

BYTE March 1978

The AJ 841 I/O.

A completely

refurbished IBM Selectric

Terminal with built-in ASCII

interface. Just $995.

FEATURES:

• ASCII code.

• 14.9 characters per second printout.

• Special introductory price —$995(regularly $1,195), 75% discount fromoriginal price of new unit.

• Parallel Interface(connector to 3P+ S included)

• Order direct fromfactory j

• Documentation Iincluded.

30-day warranty —parts and labor.

High quality

Selectric

printing.

, ■ ■'■■'■''"'

HOW TO ORDER ANAJ 841 I/O TERMINAL

1. Make cashier's check or money orderpayable to:

ANDERSON JACOBSON, INC.

Address your reduest to:Personal Computer TerminalANDERSON JACOBSON. INC,521 Charcot AvenueSan Jose, CA 95131

2. Upon written notification, pick up yourterminal at the AJ service officelocated in one of the above cities.Allow six to eight weeks for delivery.

3. A final check of your unit will be madeat the local AJ service office at time ofpickup.

4. For warranty or repair service, returnunit to designated service location.

5. Available in U.S. only.

• Reliable, heavy duty Selectricmechanism.

• Off-line use as typewriter.

AJ 841 WARRANTY AND SERVICEIS AVAILABLE IN THEFOLLOWING CITIES:

Los Angeles/CincinnatiPhiladelphia / DetroitHackensack / DallasColumbus / HoustonCleveland/AtlantaSan Jose/ChicagoBoston /New YorkWashington, DC.

For furtherinformation call(408) 263-8520

ANDERSONJACOBSON

Anderson Jacobson, Inc., 521 Charcot AvenueSan Jose. California 05131

CUP AND MAIL WITH ORDER

Number of units.

@ $995 each

Sales tax at delivery location

Shipping and handling $35each [excluding San Jose)

TOTAL

NAME.

ADDRESS .

CITY.

. STATE .

.ZIP.

PHONE I

Circle 4 on inquiry card.

BYTE March 1978

19

Photo 2: The Apple II in a typical use setting. The television is fairly far awayfrom the computer itself in order to minimize interference and hashgenerated by the logic circuitry. An inexpensive cassette recorder withturns counter is used to provide mass storage for programs.

purposes, I knew that in principle I shouldbe able to create something like photo 1.Later in this account, I will present thedetail design of software which will enablethe Apple II user to doodle as I did. Imake no claims to great artistic genius, butthe ability to do this sort of doodling, aswell as much more serious computing in autilitarian mode of operation, is what thepersonal computer is all about. Apple IIis a self-contained package which talks toa color television set owned by its user,an audio cassette recorder supplied by theuser, two control paddles supplied by themanufacturer, and a "kluge harp" styleaudible annunciator which can be pro-grammed to play music or make a varietyof noises. Much of the detail of the systemdesign of the Apple II has already beenpresented in these pages in the form of anarticle by its designer, Stephen Wozniak,which appeared in the May 1977 BYTEon page 34. This article will survey thereactions I have had to using this systemin the four weeks or so following itsarrival.

Externals

The physical appearance of the Apple IIin its normal usage context is illustrated inphoto 2. The package in which the system iscontained is a high strength injection moldedplastic material with a metal bottom plate.The plastic parts are painted an off-whiteivory color. The three piece case consists

of a body with a door on the top for accessto the internal works and peripheral sockets.The case is almost empty when the Apple IIarrives, and when carrying the computeraround in its optional leatherette bag mycommon practice has been to take the coveroff and insert various paraphernalia cushionedby foam plastic to avoid damaging the circuitboards. (If I had any peripherals plugged intothe 10 bus of the machine, this would notnecessarily be a good idea.) When zipped upin its carrying bag, the Apple II looks likean overgrown pocket calculator. I have takenthis computer in its case to friends' homesand with me on trips by airplane (where itfits under the seat as "carry on" luggage). Ifthe destination of one's travels has a colortelevision, and a miniature cassette recorderis packed with the Apple II, then this com-puter can be considered to be truly portableand adds but one bag to the normal comple-ment of travel luggage.

While the case is elegantly styled, as canbe seen from photo 2, there are two minorproblems related to the mechanical designof this case. The problems relate to the topof the case and how it fits into the mainbody of the computer. One problem is thefact that the adhesion between the paint ofthe case and the plastic is not strong enoughto keep the fasteners in place. After Iopened the top a few times both fastenersbroke loose. The second mechanical designglitch is the fact that if the cover is movedmore than about 5 or 10° from horizontalbefore it is slid out from under the frontedge of the case, a leverage effect will tendto extract the keyboard from its moorings.

A usable configuration of the Apple II asemphasized in photo 2 is made up of thecomputer, a color television, and a cassetterecorder. The standard game paddles whichcome with the system allow interactivegraphic applications. The use of a colortelevision is highly recommended, althougha black and white set will certainly work, atthe expense of one of the unique featuresof Apple II, its color display.

There are two methods of sending videodata to the television set from the Apple.The best option, which is often used bycomputer stores to show off the system, isuse of direct video. However, stock colortelevisions or color monitors with directvideo entry are rare and expensive. A lesssatisfactory but quite workable methodis the use of a radio frequency modulatorto generate a television "station" on channel3, with connection via the antenna terminalsand an FCC approved antenna isolationswitch which mounts on the back of the set.This method of driving the television is the

20

BYTE March 1978

C-KXX)

THE FIRST TV CAMERA DESIGNED FOR

COMPUTER INTERFACE

SUPERB RESOLUTION—

Observe minute detail with resolution over1000 TV lines.

VIRTUALLY DISTORTION-FREE—

Image is accurate, linear from center of screen to outeredge with less than 0.2% distortion.

STABLE—

Less than 0.05% drift per 24 hours, less than 0.2% from10° C to 40° C.

PLUS ALL LINES NEEDED FORDIGITAL AND ANALOGCOMPUTER INTERFACE

THIS UNIT IS "INSTRUMENT QUALITY"—NOT A VIDEO SYSTEM FORENTERTAINMENT VIEWING

APPLICATIONS:

MEDICAL

Tissue analysis

Blood analysis

Neurological—X-Y movement analysis

Optical Instrument data analysis

Other analysis of visual data

INDUSTRIAL

Aerial photography analysis—crop areas,

insect infestationIR Analysis—detect forest fires, direct robot

firefightersBottle inspection—using polarized lightDimension analysis and control, area

measurement, displacement measurementPrinted pattern analysis and controlMissile trackingUNIVERSITYAnalysis of any visual information that can be

measured through variation in light intensityMedical researchPhysics researchLaser technology

Circle 50 on inquiry card.

HAMAMATSU CORP. • 120 WOOD AVENUE • MIDDLESEX, NEW JERSEY 08846 • (201) 469-6640

BYTE March 1978 21

Photo 3: Removing the cover and looking straight down into the unit, themajor internal subassemblies can be seen. At the left is the proprietaryswitching power supply unit; at the right along the bottom of the cabinet isthe main processor board, with room for 48 K bytes of programmable usermemory (using 16 K memory parts) and an 8 slot 10 bus used to interconnectperipherals. At the right toward the rear of the cabinet (top of photo) is theRF modulator used to drive the television on channel 3. The keyboard can beseen toward the lower edge of the photo.

one used in all the photographs and listingsaccompanying this article.

The main problem with direct RF entryas a method is the tendency of the televisionset's tuner to pick up RF hash from the digi-tal logic of the computer, a problem whichwas quite severe in my experience, using aPanasonic color television. The degree ofinterference is dependent upon the exactpositioning of the cable, the television andthe computer relative to its various powerand peripheral cables. The problem can beminimized, as shown by the fact that in thelistings and photos of this article 1 was able

to get a clear picture; but I do not recom-mend use of a Panasonic television likemine with the Apple II. (Steve Jobs of AppleComputer suggests use of several models ofSony television sets due to superior RFshielding relative to the Panasonic set I used.)If you purchase an Apple II and a colortelevision for it, I highly recommend testingthe TV and computer combination prior tosettling on a particular television. Some com-puter stores will convert TV sets to directvideo entry, so this provides another option.

Internals

Photo 3 shows the Apple II 's interiorwith the cover removed from the case. Thecomputer is entirely contained on one largeprinted circuit board on the bottom of thecase. At the left is a large metal box contain-ing the switching regulated power supply.The printed circuit board of the keyboardassembly can be seen protruding past the lipat the front edge of the case (bottom of thephotograph). Also seen in this picture is ahomemade cable running from the game 10connector of the processor board to thejoystick box which I built for use with thecolor sketchpad program to be described.At the top right in this photograph can beseen the RF modulator unit which plugsdirectly into the main board of the compu-ter. Note that the RF cables contain largetoroidal ferrite coil forms with severalturns of the cables around them. These areused to minimize (but in my experiencewith the Panasonic television never totallyeliminate) RF hash interference in the tele-vision set when the RF modulator techniqueof video data entry is used.

The Apple II provides a decoded set ofeight 10 sockets which also feature all theprocessor bus signals. At the time the AppleII was delivered to me no peripherals wereavailable which used this bus, but I havesince seen several advertisements for prod-ucts to plug into the Apple 11 bus and theApple Computer Company is working onperipherals to extend the power of themachine. This bus is completely docu-mented and should work out well for theadvanced experimenter.

The Apple hardware includes two fairlygamey peripherals for use in family enter-tainment situations. One such peripheralis a pair of game 10 paddles consistingof an analog input lever and pushbuttonswitch for each channel. A second suchperipheral is the annunciator output whichin addition to sounding the "bell" charac-ter of ASCII can be programmed by theuser with arbitrary pitches, as a sort ofmusic synthesizer.

22

BYTE March 1978

HORIZQ

£

THE COMPLETE COMPUTER

LookToThe North Star HORIZON Computer.

HORIZON™— a complete, high-performance microprocessorsystem with integrated floppy disk memory. HORIZON isattractive, professionally engineered, and ideal for business,educational and personal applications.

To begin programming in extended BASIC, merely add a CRTor hard-copy terminal. HORIZON-1 includes a Z80A processor,16K RAM, minifloppy™ disk and 12-slot S-100 motherboardwith serial terminal interface —all standard equipment.

WHAT ABOUT PERFORMANCE?

The Z80A processor operates at 4MHZ — double the power ofthe 8080. And our 16K RAM board lets the Z80A execute atfull speed. HORIZON can load or save a 10K byte disk programin less than 2 seconds. Each diskette can store 90K bytes.

AND SOFTWARE, TOO

HORIZON includes the North Star Disk Operating System andfull extended BASIC on diskette ready at power-on. Our BASIC,now in widespread use, has everything desired in a BASIC, in-cluding sequential and random disk files, formatted output, apowerful line editor, strings, machine language CALL and more.

EXPAND YOUR HORIZON

Also available —Hardware floating point board (FPB); addi-tional 16K memory boards with parity option. Add a seconddisk drive and you have HORIZON-2. Economical serial andparallel I/O ports may be installed on the motherboard. Manywidely available S-100 bus peripheral boards can be added toHORIZON.

QUALITY AT THE RIGHT PRICE

HORIZON processor board, RAM, FPB and MICRO DISK SYS-TEM can be bought separately for either Z80 or 8080 S-100 bussystems.

HORIZON-1 $1599 kit; $1899 assembled.

HORIZON-2 $1999 kit; $2349 assembled.

16K RAM —$399 kit; $459 assembled; Parity option $39 kit; $59assembled. FPB $259 kit; $359 assembled. Z80 board $199 kit;$259 assembled. Prices subject to change. HORIZON offeredin choice of wood or blue metal cover at no extra charge.

Write for free color catalogue or visit your local computer store.

North Star * Computers

2547 Ninth Street • Berkeley, California 94710 • (415) 549-0858

Circle 83 on inquiry card.

BYTE March 1978

23

Table I: Summary ofthe Apple II 5 K BASICInterpreter.

The Processor

As documented by its designer StephenWozniak in the May 1977 BYTE, the designof the Apple II system uses the 6502 pro-cessor created by MOS Technology and nowavailable from several sources. The designhas a certain elegance which comes from asimple combination of the video displaygeneration, dynamic memory refresh andprocessor clock timing based on a single

Variables: Names may be from 1 to 100 characters in length. Data type is numeric unlessname is followed by the character "$".

Numeric Variables: May be arrayed up to the limits of available memory with DIM state-ment. Precision is 16 bits,signed two's complement representation with range -32768to+32767.

String Variables: DIM statement sets length other than default, from 1 to 255 charactersper string.

Speed: Executes the loop 100 FOR 1=1 TO 10000,110 NEXT I in about 14 seconds.

Statements:

.TO ...STEP

CALL

DIM

DSP

END

FOR ..

GOSUB

GOTO

IF ...THEN ...

INPUT

IN#

LET ... = (LET optional)

LIST

Graphic Statements:

COLOR=GR

Operators:

+

NOT

t (exponentiate)

*

/MOD

NEXT

NO DSP

NO TRACE

POKE

POP

PRINT

PR#

REM

RETURN

TAB

TEXT

TRACE

VTAB

HLINPLOTVLIN

#or <>

<

>

<=

>=

AND

OR

PEEKRNDSCRNSGN

Functions:

ABSASCLENPDL

Other features:

Branch addresses in GOSUB and GOTO and CALL can be any arbitrary numericexpression which results in a positive value. Legal line numbers are the positiveintegers 1 to 32767.

Documentation includes several PEEK and POKE strategies to access hardware suchas speaker, paddle pushbutton switch inputs, etc.

Other Features: Interpreter Control

AUTO LOAD

CLR LOMEM

CON (or control C) MAN

DEL NEW

DSP NO DSP

HIMEM NO TRACE

GOTO RUN

GR SAVE

LIST TEXT

TRACE

crystal oscillator. I'll not repeat the detailshere, but simply summarize: the two phasenature of the 6502 clock is such that theprocessor turns itself off with respect to theoutside world during one phase, and accessesmemory during the other phase. By usingthe phase unused by the processor for accessof memory by the video display generationlogic, there is never any conflict betweenthe display and the processor's access ofmemory. As a side effect, since the displaygenerator is always cycling through thelow order address bits of the dynamicmemory content of the machine, the dy-namic memory refresh requirements are metby this regular access of memory for displaypurposes.

The memory address space of the AppleII is partitioned into three major segments.The region from addresses hexadecimal 0to BFFF (48 K bytes) is reserved for pro-grammable user memory, implemented withdynamic memory parts. The region fromD000 hexadecimal to FFFF hexadecimalis reserved for systems software in read onlymemory, and IO ports are found in theCOOOtoCFFF region.

The user memory region can have anycombination of three 4 K or 16 K byteregions depending upon which memorychips one plugs into three sets of eightsockets. Thus the Apple II can be had with4K, 8 K, 12 K, 16 K, 20 K, 24 K, 32 K,36 K or 48 K bytes of memory at theuser's option. For full use of the capa-bilities of the machine I would not rec-ommend purchasing less than 16 K bytesof memory.

The read only memory regions covera total of 12 K bytes in the address space,starting at D000 and extending throughFFFF. In the versions of Apple II currentlybeing delivered, four 2 K byte read onlymemory parts are plugged into addressesE000 through FFFF, giving a total of 8 Kbytes of systems software and leaving two2 K byte sockets unused. The presentROM load includes 5 K for the integerBASIC interpreter, 1 K for miscellaneousutility routines, and 2 K for the systemmonitor program.

Systems Software

As with all the self contained "complete"computer systems, Apple II is ready andwilling to act as a personal computer ser-vant as soon as the power is turned on andthe "reset" button on the keyboard ispushed. This capability for instant use isachieved by the systems software contained

Continued on page 30

24

BYTE March T 978

■■■■■H

Hie Computer for the Professional

Whether you are a manager, scientist, educator, lawyer,

accountant or medical professional, the System 8813 will

make you more productive in your profession. It can keep

track of your receivables, project future sales, evaluate

investment opportunities, or collect data in the laboratory.

Use the System 8813 to develop reports, analyze and store

lists and schedules, or to teach others about computers.

It is easily used by novices and experts alike.

Reliable hardware and sophisticated software makethis system a useful tool. Several software packages areincluded with the machine: an advanced disk operatingsystem supporting a powerful BASIC language inter-preter, easy to use text editor, assembler and other systemutilities. Prices for complete systems start at $3250.

See it at your local computer store or contact us at460 Ward Dr., Santa Barbara, CA 93111, (805) 967-0468.

PolyMorphicSystems

BYTE March 1978

25

New iCOMAttache

A serious small system for practical computing

Tinker-time is over for many small-computer users. You're ready formore powerful, more professionalequipment—to replace earlykluged systems, or for easiercomputer ownership.

We're ready too. With Attache—handsomely produced by iCOM9pros, strengthened by our PertecComputer Corporation family ties.Already first in Microperipherals,®we've expanded our industrycommitment, to provide completeturnkey systems backed by PCC'sfull technical resources.

Take Attache seriously.

At last a no-nonsense desktopcomputer: highly advanced, butyou don't have to be an engineer torun it. And flexible enough forapplication versatility.

Heavy-duty powered, Attache'sS-100 bus mainframe offers 10-slot accommodations. For 8080microprocessor, video, andturnkey monitor boards, for full64-character ASCII keyboard.With room to spare for user options:plug in 16K memory, cassetteinterface (KCACR), I/O, processcontrol, and/or iCOM floppy diskinterface cards.

With serious software support.

Attache software options takeadvantage of iCOM's solid expe-rience: field-proven FDOS-lirDisk Operating System; relocatableassembly language developmentsystem; and DEBBrthe Disk-Extended BASIC by iCOM.

iCOM: right, from the start.

Now the most-trusted name inMicroperipherals can satisfy yourtotal system requirements. Witha serious computer worthlooking into today at your localcomputer store.

Products of !£■« Pertec Computer Corporation

20630 Nordhoff Street, Chatsworth. CA 91311.Telephone: (213) 998-1800. TWX: (910) 494-2093.

Built and backed by Pertec Computer Corporation, (world's leading independent producer ol computer peripheral equipment and distributed processing and data entry systems).

26

BYTE March 1978

© 1978, iCOM* is a registered trademark of Porlec Compuler Corporation

Circle 94 on inquiry card.

VISIT YOUR NEARESTMITS DEALER

ARIZONA:

Altiar Computer Center

4941 East 29th Street

Tucson. AZ 85711

602/748-7363

Contact: Armand Sperduti

Southwest Micro-Systems, Inc.

3815 North Third Street

Phoenix, AZ

602/957-3738

Contact: Darryl C. Goebel

ARKANSAS:

JFK Electronics

3702 JFK Blvd.

No. Little Rock, AK 72116

501/753-1414

Contact: George Luijet

CALIFORNIA:

Computer Kits

1044 University Avenue

Berkeley, CA 94710

405/845-5300

Contact: Pete Roberts

The Computer Store

820 Broadway

Santa Monica. CA 90401

213/451-0713

Contact: Dick Heiser

COLORADO:

Gateway Electronics of St. Louis

2839 West 44th Avenue

Denver, CO 80211

303/458-5444

Contact: George Mensik

Sound-Tronix

900 Ninth Avenue

Greeley, CO 90861

303/356-1588

Contact: Ronald Schuster

(have two other locations

in Colorado)

FLORIDA:

Altair Computer Center of Miami,

Inc.

Opa Locka Airport

Miami, FL 33166

305/688-0569

S.E. Micro-Data Corporation

6020 South Orange Blossom Trail,

Suite 602

Orlando, FL 32807

GEORGIA:

The Computer Systemcenter

3330 Piedmont Road, N.E.

Atlanta. GA 30305

404/231-1691

Contact: Rich Stafford, Lou Darby

ILLINOIS:

Chicago Computer Store517 Talcott RoadPark Ridge, IL 60068312/823-2388Contact: Lou Van EperenChicago Computer Store4919 "B" North Sheridan RoadPeoria, IL 61614309/692-7704

INDIANA:

Indianapolis Office Machines6433 East Washington AvenueIndianapolis, Indiana317/353-9315

KANSAS:

Advanced Micro Systems, Inc.7751 EnglandOverland Park, KS913/649-2347Contact: Phil Bouldin

KENTUCKY:

The Computer Store

Suite 5

Municipal Parking Bldg.

Charleston. West VA 25301

304/845-1360

Contact: Steven C. Payne

MICHIGAN:

The Computer Store of Detroit

505-507 West 11 Mile Road

Madison Heights, Ml 48071

313/545-2225

Contact: Pete Blond

The Computer Store of Ann Arbor

310 East Washington Street

Ann Arbor, Ml 48104

313/995-7616

Contact: Pete Blond

MINNESOTA:

The Computer Room3938 Beau D'Rue DriveEagan, MN 55122612/452-2567Contact: Roger Hensen

MISSOURI:

Gateway Electronics of St. Louis

8123-25 Page Blvd.

St. Louis, MO 63130

314/427-6116

Contact: Lou Elkins

NEBRASKA:

Altair Computer Center

611 North 27th Street

Lincoln, NE 68503

402/474-2800

Contact: Steve Conover

NEW MEXICO:

Computer Shack

3120 San Mateo N.E.

Albuquergue, NM 87110

505/883-8282

Contact: Pete Conner

NEW YORK:

The Computer Store of New York

55 West 39th Street

New York, NY 10018

212/221-1404

The Computer Store

269 Osborne Road

Albany, NY 12211

518/459-6140

Contact: Charlie Olds

NORTH CAROLINA:

Computer Stores of Carolina1808 East Independence Blvd.Charlotte. NC 28205704/334-0242Contact: Grey Hodges

OHIO:

Altair Computer Center

5252 North Dixie Drive

Dayton, OH 45414

513/274-1149

Contact: John & Judy Potter

The Computer Store of Toledo

8 Hillwyck Street

Toledo, OH 43615

Southern Medical Clinic

3700 South Parsons Avenue

Columbus, OH 43207

614/497-1366

Contact: Dr. Robert Bertani

OKLAHOMA:

Altair Computer Center110 The Annex5345 East 41st StreetTulsa, OK 74135918/664-4564Contact: Ray Koons

OREGON:

Altair Computer Center8105 S.W. Nimbus AvenueBeaverton, OR 97005503/644-2314Contact: Dick Landon

PENNSYLVANIA:

Microcomputer Systems Inc.243 West Chocolate RoadHershey, PA 17033717/533-5880Contact: Walter HiesterFive H Corporation740 Huntersrun RoadPottstown, PA 19464Contact: Michael HegedusTEXAS:

Swift Computers, Inc.

Suite 206

3208 Beltline Road

Dallas, TX 75234

Contact: Carl Swift

Swift Computers, Inc.

Fort Worth, TX

214/241-4088

Contact: Carl Swift

Burcon, Inc.

5750 Bintliff Drive

Suite 206

Houston, TX 77036

713/780-8981

Contact: Bob Burnett, Mike Conley

Computronics

5415 25th Street

Lubbock, TX 79407

806/797-4495

UTAH:

Microcosm Incorporated

534 West 9460

South Sandy, UT 84070

801/566-1322

Contact: John D. Anderton

VIRGINIA:

Computers-To-Go

1905 Westmoreland Street

Richmond, VA 23230

804/355-5773

Contact: Becky Willis

Microsystems Computer

Corporation

Century Mall-Crystal City

2341 South Jefferson Davis

Highway

Arlington, VA

703/569-1110

Contact: Russ & Gloria Banks

Megabyte Computer Association

700 Stoney Point, Suite 7

Newtown Road

Norfolk, VA 23502

WASHINGTON:

Altair Computer Center8105 S.W. Nimbus AvenueBeaverton, OR 97005503/644-2314 .Contact: Dick Landon

WEST VIRGINIA:

The Computer Store

Municipal Parking Bldg.

Suite 5

Charleston. West VA 25301

304/345-1360

Contact: Stephen C. Payne

WISCONSIN:

Chicago Computer Store285 West Northland AvenueAppleton, Wl 54911414/731-9559

BYTE's Bits

How the BOMB Breaks

What do BOMB ratings mean? We'lllet readers figure this out, since readersjudge the articles on a personally sub-jective scale from O to 10. Let X; bethe total of all ratings by all BOMB cardsfor article j. What we do is execute thefollowing procedure:

Mean:

Standard

5f=(,2Xi)/n

1=1

,)=n .

a=SQRT(JS (Xj-X)2)Deviation ,•=-]

Then the "figure of merit" for a givenarticle j is given by the expression:

Figure of Merit: f = (Xj - X) / a

It is clear that f is determined by thereaders who send in filled out BOMBcards."

Attention 6502 Users. . .

Micro, the 6502 Journal is the nameof a new publication put out by RobertTripp (published bimonthly, $6 perannum, by The Computerist, 8 FourthLn, South Chelmsford MA 01824). Wejust received the second issue of thisphoto-offset publication, and the con-tents should please all users of Apple-ll,KIM-1, OSI, PET 2001 and othermachines with 6502 Central processorchips. The second issue was 30 pageslong and contained 12 items listed in itstable of contents, along with advertise-ments of ten companies specializing inthe 6502 marketplace the publicationaddresses. The $6 spent on a subscrip-tion to Micro will be well worthit. . .CH"

Detroit ACM Seminars To BeHeld in April

The Metropolitan Detroit Chapter ofACM announces its Sixth Annual Pro-fessional Development Seminars to beheld on Tuesday and Thursday eveningsduring April at the Lawrence Institute ofTechnology which is accessible byexpressway (I-96) from most of South-eastern Michigan.

Topics and instructors include: struc-tured programming, Michael Marcotty;computer networks, Eric Aupperle; database management systems, Alan Merten,James Fry and Toby Teorey; operatingsystems, Ronald Srodawa; computergraphics, John Dill; and design validationof real time microprocessor software,Ronald Temple.

For a program brochure, write ACM,POB 1091, Warren Ml 48090."

BYTE March 1978

27

The all newmnemonics

^V

k

revised 2nd Edition...with industry standard...has just arrived! Plus, a special bonus!

Scelbi has done it again. Here isthe great book that lets you cookup appetizing, hot programs foryour own '8080'. And, now,it's been completely revised, andrepublished, to reflect the latestindustry standard mnemonics.This tasty delight of all newsecond generation software foryour '8080' is chock full of mouthwatering applications to satisfythe most fussy palate. It's amouthwatering delight.

Over 200 pages. Chock fullof action, facts.

You'll devour the contents ofthis action-packed, information-stuffed book. Gobble up practical'how to' facts. The description ofthe '8080' instruction set. How tomanipulate the '8080' stack. Flowcharts and source listings. Generalpurpose routines for multipleprecision operation. Programmingtime delays for real time applica-tions. Random number generators.And many, many more basicprogramming functions you cansink your teeth into.

Three versions now available.

That's right. Now there arethree versions of this great book.The DeLuxe Hardcover edition,a must for any library, is only$14.95. The new heavy-duty Vinylcovered edition, for the hardworking, heavy computer user, isonly $12.95. The same facts arepacked into an economical paper-back edition for a low, low $10.95.

Floating Point ArithmeticRoutines.

The new 2nd edition of thefamous Scelbi Cook Book evenincludes completely assembled

Scelbi

. J3B080"Software

gourmet guide

floating point arithmetic programs(worth the price of the bookalone!) .. . plus input/outputprocessing for your basic I/Oprogramming through interruptprocessing. There are code andnumeric conversion routines. Realtime programming. Search andsort routines. And too manyhnger-lickin' goodies to mentionhere.

'8085' users will find a fountainof champagne facts in here too.

SPECIAL BONUS OFFER!

'8080' Pocket Guide Bonusoffer.

If you act right now you canown Scelbi's equally famous '8080'Programmer's Pocket Guide, acompact, pocket-size, instantreference that explains the in-struction set in detail (duplicatesChapter 1 of the Cook Book),giving both octal and hexadecimalcodes. It normally sells for $2.95.Order your copy of Scelbi "8080"Software Gourmet Guide & CookBook now, and the Pocket Guideis yours for only $2.00!

Don't delay. Order your copytoday.

You've heard about this greatbook. Here's your chance to ownthe updated, current edition inone of three versions to fit yourbudget. It's everything the com-puter chef needs. And, you can'tbeat the price ... or the bonusoffer. Order your copy today.Scelbi's "8080" Software GourmetGuide & Cook Book. Write toScelbi Computer Consulting, Inc.;P.O. Box 133 PP STN,Milford, CT 06460.

Act now and you canScelbi's popular '8080'grammer's Pocket Guide.compact book, 3"x41/2",

ownPro-Thisslips

into your pocket, so you cancarry it with you everywhere,t's an ever-ready instant ref-erence for operation of your'8080'. It explains the instruc-tion set in painstaking detail,and gives both octal and hexa-decimal codes. This valuablebook regularly sells everywherefor $2.95. If you order your 2ndEdition Cook Book now, youcan also purchase the Pocket Guidefor a low, low $2.00. Do it now!

Price shown lor North American customers. MasterCharge, Postal and Bank Money Orders preferred.

Personal checks delay shipping up to 4 weeks.

specifications, availability subject tochange without notice. SCELBI Books are available

Pricing,

in many fine Computer Stores. IMPORTANT! In-clude 75< postage/handling for each Itemdelivered by U.S. Mail Book Rate; or S2 for eachitem shipped First Class or via UPS.

DeLuxe Hardcover Edition, now only $14.95Durable Vinyl covered Edition, now $12.95Economical Paperback Edition, now $10.95

Circle 100 on inquiry card.

Continued from page 24

in the 8 K byte read only memory. Onreset, the system monitor program is en-tered, with an asterisk (*) returned to thevideo display as a prompting character.The functions available from this programinclude hexadecimal manipulations of mem-ory contents: displaying memory, changingmemory contents, moving blocks from placeto place in memory, comparing blocks inmemory, reading or writing memory blocksto tape. At a slightly higher level, there isa "mini-assembler" which does operationcode lookup and branch address calcula-tion, and a disassembler which inverts theoperation of the assembler. The monitoralso includes provisions for machine lan-guage tracing of programs, single stepexecution of machine language programs,and hexadecimal arithmetic of additionand subtraction. This software providesthe basis for effective low level use of the6502 processor, and in fact was used byApple ll's designer Stephen Wozniak asone of the key software development toolsin implementation of the 5 K Apple BASICinterpreter which makes up the remainderof the 8 K software in read only memory.

The 5 K Apple BASIC interpreter isentered from the system monitor throughuse of a "control B" command followed

Table 2: Summary of Apple II features.

Processor: 6502 running at 1.023 MHz

User Memory Capacity: Three banks of eight 4 K or 16 K dynamic memory parts4 K, 8 K, 12 K, 16 K, 20 K, 24 K, 32 K, 36 K or 48 K bytes

Read Only Memory Capacity:

12 K bytes using 2 K by 8 bit ROM parts, 8 K installed

Standard Peripherals:

Two game paddles (one switch, one variable analog input per paddle)

Programmable annunciator

ASCII keyboardAudio tape mass storage (approximately 1500 bps)NTSC color video generation for primary display

Optional:

RF modulator for video coupling to standard television

Expansion Capabilities:

Eight IO connectors with 50 pins:Full address bus (16 pins)Full data bus (8 pins)Timing signalsDMA signalsDevice select signals

Software:

System monitor (2 K bytes, ROM)

Utility routines (1 K bytes, ROM)

Integer BASIC interpreter (5 K bytes, ROM)

Full extended BASIC (Applesoft, loaded from tape, requires 16 K user memory)

Applications software examples including games, accounting, etc

by a carriage return. This sequence resultsin the 5 K BASIC interpreter's promptof an angle bracket (>). The 5 K inter-preter built into the Apple II is an integerBASIC with 16 bit precision and a signedtwo's complement number representation.Table 1 summarizes the characteristics ofthis BASIC. Built into the language are anumber of extensions which are used tocontrol special hardware and the graphicsof the Apple II color display. These exten-sions include the commands GR, TEXT,PDL (read a control paddle), SCRN (extractthe current color of a point on the screen),COLOR=, PLOT, VLIN (draw verticalline) and HLIN (draw horizontal line).Using this 5 K BASIC I was able to imple-ment the color sketchpad program shownin the listings of this article, in about threeevenings of experimentation which mostlyconcerned defining just what the programmust do.

The 5 K BASIC interpreter which is builtinto the Apple is all that is needed for imple-mentation of most types of interactivegames involving color graphics and reactiontimes on the part of the user. But the 5 KBASIC, even given its string capabilities,is not what one would want to use to doa simulation of a physical system or cal-culate quantities other than integers.

As an answer to the need for an extendedBASIC as a language for the Apple II,there is the "Applesoft" extended BASICinterpreter which can be used in systemswith 16 K bytes of memory or more. Thename "Applesoft" is a cross between thesource of the interpreter, the Microsoftcompany, and a gross pun ("applesauce").This interpreter is nearly identical to theMicrosoft extended BASIC interpreterswhich have been made available for a num-ber of personal computer products. Thepeople at Apple have hacked the interpreterto include a few variations on the standardversion which address the color displayhardware. The only relative novelty of thishack is that in order to get graphics exten-sions, they had to sacrifice two statements:LET and REM. Thus, on initialization ofApplesoft, the user is given the option ofhaving LET and REM but no built-ingraphics primitives, or having graphics butno LET and REM statements. Since LETis totally optional in assignments, its lossis hardly felt; but the lack of remarks maybe felt by self-documenting code puristswho want to use the graphics mode ofApplesoft. Of course not having the primi-tives does not prevent use of the graphicshardware, since like all Microsoft inter-preters, Applesoft has PEEK and POKE

30

BYTE March 1978

OUR STARPERFORMERSFORTHES-100BU

Meet The North Star Family

THE NORTH STAR S-100 FAMILY—four high perform-ance products at attractive low prices. Our boards aredesigned for use in the North Star HORIZON computerand other S-100 bus computers using 8080 or Z80 proces-sors. Visit your computer store for a demonstration, orwrite for our free color catalog.

16K RAM BOARD

No other S-100 bus memory can match the performanceof the North Star 16K RAM at any price. This low-powerboard has been designed to work at full speed (no waitstates), even at 4MHz with both Z80 and 8080 systems.Memory refresh is invisible to the processor, bank switch-ing is provided and addressability is switch selectable intwo 8K sections. Best of all, a parity check option is avail-able. Kit: $399. Assembled: $459. Parity Option — kit:$39. Assembled: $59.

MICRO DISK SYSTEM

The North Star MDS is a complete floppy disk system withall hardware and software needed to add floppy diskmemory and a powerful disk BASIC to S-100 bus com-puters. The North Star MDS is widely considered one ofthe best designed and most complete S-100 bus products

available. The MDS includes the S-100 interface boardwith on-board PROM for system startup, Shugart mini-floppy disk drive, cabling and connectors, and DOS andBASIC software on diskette. Kit: $699. Assembled: $799.Additional drive — Kit: $400. Assembled: $450. SingleDrive Cabinet: $39. Optional Power Supply: $39.

Z80A PROCESSOR BOARD

The North Star ZPB brings the full speed, 4MHz Z80Amicroprocessor to the S-100 bus. Execution is more thantwice the speed of an 8080, and the ZPB operates in sys-tems both with and without front panels. The ZPB in-cludes vectored interrupts, auto-jump startup, and spacefor 1K of on-board EPROM. Kit: $199. Assembled: $259.EPROM Option — kit: $49. Assembled: $69.

HARDWARE FLOATING POINT BOARD

If you do number crunching, then this board is for you.The FPB performs high-speed floating point add, subtract,multiply and divide with selectable precision up to 14decimal digits. Arithmetic is up to 50 times faster than8080 software, and BASIC programs can execute up to10 times faster. A version of North Star BASIC is included.Kit: $259. Assembled: $359. Prices subject to change.

Circle 83 on inquiry card.

North Star * Computers

2547 Ninth Street • Berkeley, California 94710 • (415) 549-0858

BYTE March 1978

31

Photo 4: An example ofthe high resolutiongraphics hardware of theApple II is provided bythis photo. Although fournominal colors are avail-able, this photo illustrateshow some subtleties ofcolor can be obtained bytaking advantage of thedistortions inherent in thetelevision set when mani-pulating controls. Thisdemonstration is one ofseveral options availablein the high resolutiongraphics demonstrationprogram of Apple II.

primitives and all hardware addresses aredocumented in the Apple II.

The Applesoft interpreter is loaded fromits cassette tape using the LOAD commandof the 5 K interpreter. It takes about oneminute and 30 seconds to do this load,which results in what 5 K BASIC thinksis a really big application program, but whatis in effect the object text of the new inter-preter plus a 5 K BASIC program whichpresents an interactive setup sequence.After loading this pseudo 5 K BASIC text,the user types RUN, and the interactivesetup sequence is entered. This sequenceincludes the option to display a summaryof Applesoft BASIC commands which isalso available on a reference card. Afterthe setup sequence, the Applesoft inter-preter is entered, as indicated by a rightsquare bracket prompt character (]). With a16 K Apple II system, the user gets themessage "5615 BYTES FREE" at theconclusion of the setup sequence.

Running the same rather incompletebenchmark as is found in table 1, I foundthat the Applesoft interpreter running inan Apple II took 12 seconds for 10000iterations of a null loop.

Tape Mass Storage

The Apple II tape mass storage systemaccomplishes its purposes of storing and

recovering files of data. I have proven thisto my own satisfaction by using the sys-tem. For both the 5 K BASIC and ApplesoftBASIC, SAVE and LOAD operations featurea "beep" from the Apple ll's annunciatorfollowing the leader at the beginning of thefile, and at the end of the operation. Thereis no such audible feedback when using thetape with system monitor commands.

It is the user's responsibility with theApple II tape system to keep track of fileson a piece of paper or in a log book. Thesoftware of the tape system does not includeany naming of files in file headers. It alsodoes not include any "verify" commandfor those of us who would like to make surethat a file is properly written before pullingthe plug and closing down at the end of anevening's programming.

The act of loading a file involves the userpositioning the tape just past the start ofthe leader tone for the file, issuing theproper command up to the point of thecarriage return which completes the com-mand line, then simultaneously starting therecorder and hitting the carriage return key.

High Resolution Graphics Software?

The one item of systems software whichhas been promised but not yet (December

Continued on page 35

32

BYTE March 1978

The difference is value.Take a look at our low-costmicrocomputer's heavy dutycabinet. Even with the coverremoved, it maintains its rigidstructural integrity. But wedon't stop there. Quality builtVector Graphic products, fromboards and kits to completesystems — such as ourMemorite turn-key text editorshown below — beat allcompetitors in mechanical,thermal and electrical design.

Based on an 8080Amicroprocessor and the S-100bus structure, Vector Graphicmicrocomputers are compatible(with the exception of minor I/Opatches) with all of the current8080A software.

If you're designing smallbusiness systems, text editors,control equipment, games oreven microprocessordevelopment, it will pay you tolook into our low costmicrocomputers and interfaceboards, kits or assembled.

Rush me details today.

Yes, I'm interested in:

□ Systems □ Boards, kits orassembled □ Microcomputers

Name

Firm

Phone

Address

City/State/Zip

Vector Graphic Inc.,790 Hampshire Rd., WestlakeVillage, C A 91361 (805) 497-6853

rcH graphic inc.

"1

Sold and serviced nationally.

Vector Graphic's microcomputer:What's in it for you?

Word processing systems for $7,950 — features normally found in systems costing twice as much.Circle 100 on inquiry card.

BYTE March 1978 33

why the last busis the best bus

If you want to be better, youhave to be willing to makechanges. So, when we starteddesigning our H8 Computerback in 1975, we put aside a lotof pre-conceptions to design abetter computer. For instance,instead of slavishly adoptingan inferior bus as a "standard,"we designed our own. Weused fifty fully-buffered linesbecause that's all we reallyneeded with the H8's built-insystems controller. The result?Clean signals, minimumnoise and great expansioncapabilities.

Next, we picked a male/fe-male connector. Not only is itless expensive than edge con-nectors, our tests show it'salso more reliable I And be-cause it costs less, every H8motherboard includes all theconnectors you need for ex-pansion. There's nothing extrato buy.

The connectors are mountedon the right side of the cabinetat an angle so the boards tiltback. That gives us a couple ofsignificant advantages. First,it allows the boards to belarger without requiring ataller cabinet. So our circuitboard layout is more open,which makes the boardseasier to build - even if you'venever built a kit before. Sec-ond, the angled mountingprovides easy accessibility toall the components on the faceof the boards without an ex-tender. (Many times an exten-

der alters the transmissioncharacteristics of the bus,which masks the problemyou're trying to solve or evencauses new ones.)

And we plan to support the H8bus. In the future you can ex-pect to see many new andexciting accessories for the H8bus like higher density, lowerpower memories and a varietyof unique I/O interfaces.

We're very happy with our bus,and we think you will be, too.

Who minds being different...as long as you're better.

_ HeathkitCompute

Heathkit Catalog

rTwrffSS

■ Read about nearly

■ 400 money-saving,A fun-to-build:aa» electronic kits.

00-

1 Use coupon to send for

-*" f vour mail order catalog

or bring coupon to a

~^jg&M Heathkit Electronic

Center for your catalog.

Schlumberger

Heath Company, Dept. 334-390Benton Harbor, Ml 49022

Please send me my FREE Catalog. I am not on your mailing list.

Name-

City.

CP-138

L

34 BYTE March 1978

_ State_2ip_

AVAILABLE LOCALLY ATHEATHKIT ELECTRONIC CENTERS

(Units of Schlumberger ProductsCorporation) Retail prices on someproducts may be slightly higher.

ARIZONA: Phoenix, 85017, 2727 W. Indian SchoolRd., Phone: 602-279-6247; CALIFORNIA: Anaheim,92805, 330 E. Ball Rd., Phone: 714-776-9420; ElCerrilo, 94530, 6000 Potrero Ave., Phone: 415-236-8870; Los Angeles, 90007, 2309 S. Flower St.,Phone: 213-749-0261; Pomona, 91767,1555 OrangeGrove Ave. N., Phone: 714-623-3543; RedwoodCity, 94063, 2001 Mlddlefield Rd., Phone: 415-365-8155; Sacramento, 95825,1860 Fulton Ave., Phone:916-486-1575; San Diego (La Mesa, 92041), 8363Center Dr., Phone: 714-461-0110; San Jose (Camp-bell, 95008), 2350 S. Bascom Ave., Phone: 408-377-8920; Woodland Hills, 91364, 22504 VenturaBlvd., Phone: 213-883-0531; COLORADO: Denver,80212, 594C W. 38th Ave., Phone: 303-422-3408;CONNECTICUT: Hartford (Avon, 06001), 395 W.Main St. (Rte. 44), Phone: 203-678-0323; FLORIDA:Miami (Hialeah, 33012), 4705 W. 16th Ave., Phone:305-823-2280; Tampa, 33614, 4019 West Hills-borough Ave., Phone: 813-886-2541; GEORGIA:Atlanta, 30342, 5285 Roswoll Rd., Phone: 404-252-4341; ILLINOIS: Chicago, 60645, 3462-66 W. De-von Ave., Phone: 312-583-3920; Chicago (DownersGrove, 60515), 224 Ogden Ave., Phone: 312-852-1304; INDIANA: Indianapolis, 46220, 2112 E. 62ndSt., Phone: 317-257-4321; KANSAS: Kansas City(Mission, 66202), 5960 Lamar Ave., Phone: 913-362-4486; KENTUCKY: Louisville, 40243, 12401Shelbyville Rd., Phone: 502-245-7811; LOUISIANA:New Orleans (Kenner, 70062), 1900 VeteransMemorial Hwy., Phone: 504-722-6321; MARYLAND:Baltimore, 21234, 1713 E. Joppa Rd., Phone: 301-661-4446; Rockville, 20852, 5542 Nicholson Lane,Phone: 301-881-5420; MASSACHUSETTS: Boston(Peabody, 01960), 242 Andover St., Phone: 617-531-9330; Boston (Wellesley, 02181), 165 Wor-cester Ave. (Rt. 9 just west of Rt. 128), Phone:617-237-1510; MICHIGAN: Detroit, 48219, 18645W. Eight Mile Rd., Phone: 313-535-6480; E. De-troit, 48021, 18149 E. Eight Mile Rd., Phone: 313-772-0416; MINNESOTA: Minneapolis (Hopkins,55343), 101 Shady Oak Rd., Phone: 612-938-6371;MISSOURI: St. Louis (Bridgeton), 63044, 3794McKelvey Rd., Phone: 314-291-1850; NEBRASKA:Omaha, 68134, 9207 Maple St., Phone: 402-391-2071; NEW JERSEY: Fair Lawn, 07410, 35-07Broadway (Rte. 4), Phone: 201-791-6935; Ocean,07712, 1013 State Hwy. 35, Phone: 201-775-1231;NEW YORK: Buffalo (Amherst, 14226), 3476 Sheri-dan Dr., Phone: 716-B35-3090; Jericho, Long Is-land, 11753, 15 Jericho Turnpike, Phone: 516-334-8181; Rochester, 14623, 937 Jefferson Rd., Phone;716-244-5470; White Plains (North White Plains,10603), 7 Reservoir Rd., Phone: 914-761-7690;OHIO: Cincinnati (Woodlawn, 45215), 10133Springfield Pike, Phone: 513-771-8850; Cleveland,44129, 5444 Pearl Rd., Phone: 216-886-2590; Col-umbus, 43229, 2500 Morse Rd., Phone: 614-475-7200; Toledo, 43615, 48 S. Byrne Rd., Phone: 419-537-1887; PENNSYLVANIA: Philadelphia, 19149,6318 Roosevelt Blvd., Phone: 215-288-0180; Fraier(Chester Co.), 19355, 630 Lancaster Pike (Rt. 30),Phone: 215-647-5555; Pittsburgh, 15235, 3482 Wm.Penn Hwy., Phone: 412-824-3564; RHODE ISLAND:Providence (Warwick, 02886), 558 GreenwichAve., Phone: 401-738-5150; TEXAS: Dallas, 75201,2715 Ross Ave., Phone: 214-826-4053; Houston,77027, 3705 Westheimer, Phone: 713-623-2090;VIRGINIA: Alexandria, 22303, 6201 RichmondHwy., Phone: 703-765-5515; Norfolk (VirginiaBeach, 23455), 1055 Independence Blvd., Phone:804-460-0997; WASHINGTON: Seattle, 98121, 2221Third Ave., Phone: 206-682-2172; WISCONSIN:Milwaukee, 53216, 5215 W. Fond du Lac, Phone:414-873-8250.

Circle 52 on inquiry card.

Continued from page 32

1977) delivered to me in a documented formis the "high resolution" graphics softwarepackage. This is perhaps the best attributeof the Apple II's unique color graphicsorientation; its potential is shown by a"high resolution demo" program whichI was able to get from the company, includ-ing a number of graphic whizbangs selectedfrom a list of choices. Perhaps the bestin my opinion is something called the"Spirograph," a constantly changing colorgraphic implementation of a mandala.The illustration of photo 4 is taken fromone state of this program's execution ap-proximately six hours into its evolutionone evening. The program uses a randomnumber generator which appears trulyrandom (unrepeatable upon reloading fromthe same tape) to control the course ofthe pattern. The price of the graphicsroutines is listed as $10.

Applications Software

A mixed bag of user oriented software isavailable with Apple as a means of demon-strating the system. This includes a numberof tapes with games using the display andpaddles, a "Checkbook-Home Management"package, an excellent 16 K Star Trek gamewhich I have used on my system severaltimes, etc. Typical prices are around $10per tape, with four tapes currently listedin the catalog sheet. Users can expect moreofferings as time goes on. It is these appli-cations programs, games and graphic whiz-bangs, which provide the greatest value tome when demonstrating the concept of apersonal computer to friends.

Documentation

Aside from having a well designed hard-ware configuration, the Apple II is nothidden from the user who wants to figureout what is in his computer. The "prelimi-nary" documentation which I have on theApple 11 consists of a loose leaf file bound ina report folder which has proved anythingbut preliminary in terms of completenessand usefulness. Its contents are not exces-sively verbose, but all the essentials arepresent: the specification of the syntax ofthe 5 K BASIC, how to access systemssoftware hooks from BASIC, the completeaddress space map of the hardware, and neatcomprehensive drawings of all of the sys-tem's electronics. When it came time for meto wire up a version of the game paddles inthe form of my own joystick hack, I wasable to turn to a page of the manual con-taining a specification of all the signals onthe 16 pin game IO connector. This manual

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JOYSTICK ASSEMBLY

lOOKO

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REMOTE JOYSTICK CONTROL BOX

s,

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16 PIN DUAL IN LINEPLUG TO JI4 OF APPLE U

Figure I: Wiring of the joystick control box and cable. The box is shown inphoto 5. The cable used was made up of separate #18 stranded wires, twistedafter all interconnection to the plug had been completed.

is not a tutorial on how the computer works,but it does contain all the informationneeded for the experienced experimenter toadd custom hardware to the system. A"final" version of the manual is in prepara-tion according to the Apple Computer Co,but this preliminary manual is completeenough to stand on its own.

The only items where I found documen-tation somewhat scanty were the ApplesoftBASIC interpreter (documentation limitedto a reference card quoting the initializationtexts on how to use it), and the lack ofdocumentation of high resolution graphicsto date.

Using the Apple 11: A Color SketchpadProgram and Joystick

As a means of trying out the Apple IIsystem and its documentation, I seta goal of

Continued on page 40

BYTE March 1978

35

Basic systems forpersonal computing

If you are just getting into personal computing and are looking for a starter system,you have two choices: a computer kit with RAM memory only or a fully assembled computerwith BASIC-in-ROM. From reading this magazine and talking to computer buffs it should beobvious that it is desirable to have a computer capable of communicating in the programminglanguage BASIC. This language allows you to instruct the computer in English-like phrasesand to use any of the thousands of standard programs written in BASIC (there are probablyseveral in this magazine).

If you purchase a (RAM-only) computer kit you will have to buy additional RAM (4K to8K), a terminal, and cassette interface for a total cost of about $1000 to run BASIC after you getthe kit together and working. Your reward for this endeavor will be a wait of about 15 minutesevery time you turn the computer on just to load BASIC into the machine!

Your other alternative is a BASIC-in-ROM computer. These machines have BASICbuilt in so that it is there whenever the computer is turned on. BASIC-in-ROM computers arealso usually fully assembled and cost far less than the RAM-only kits because they are mass-produced by the thousands.

But, you must be careful when selecting a BASIC-in-ROM computer. Some modelsdo not have full-feature BASIC. Instead they have Tiny BASIC or 4K BASIC which cannot runmost of the standard BASIC programs available. Still others have other shortcomings such asa small calculator-style keyboard which makes program entry difficult, or most important,lack of expansion capability, preventing the computer from growing with you.

Ohio Scientific offers you a line of expandable computers with full-feature 8KBASIC-in-ROM. They all come fully assembled and tested, but give you the option ofeconomizing by supplying the simple things — power supply, keyboard and TV, if desired, sothat you get the most computer power for your dollar.

Compare Ohio Scientific^ $298 BASIC-in-ROM Model 500 Board (1MHz clock),which has our Version 3.3 BASIC, against other small computers, as in the independent article"BASIC Timing Comparisons" (Kilobaud, Oct. 1977, p. 23). In this test, the Model 500 excelledover all our personal computing competitors, and was second in performance only to ourChallenger disk systems, compared against twenty-eight other computer systems. And theModel 500 is our lowest-cost machine! Our larger models are even more dramatic in a com-parison with any competitive models.

Having the fastest full-feature BASIC ROMs certainly isn't the only criterionnecessary for a superior computer system, but it sure helps. Ohio Scientific offers all the otherfeatures necessary, including a full line of computer accessories complete with 15 accessoryboards available in over 40 configurations. Many Ohio Scientific accessories are so innovativethat no one else in the industry has them — such as dual port memory boards, multi-processing CPU's and big disks.

Ohio Scientific has other unique features for the personal computerist. For in-stance, there is Ohio Scientific's Small Systems Journal, published bi-monthly, a fullmagazine aimed specifically at the owners of Ohio Scientific computers. If you are looking fora personal computer, be sure to look carefully at Ohio Scientific. We think you will find that wehave the system for you.

Model 500 Board

A full 8K BASIC-in-ROM computer on a board. This unitcontains a 6502 microprocessor with our powerful 8KBASIC-in-ROM, 4K of RAM memory, and a serial portwhich can be jumpered for 20ma current loop or RS-232.The board can be plugged into any standard OSI-backplane and expanded by our full line of accessoryboards. The user must simply supply +5Vand -9V powerand the serial terminal to be up and running in BASIC.$298.00

Super Kit

An ideal starter computer system. The Super Kit includesa Model 500 CPU Board with 8K BASIC in ROM, CPU, and4Kof RAM, full buffering for expansion, an eight-slot back-plane board, and a Model 440 Video I/O Board. Model 440provides full CRT functions when connected to a videomonitor or modified television set and a standard ASCIIkeyboard. The user must simply provide +5V and -9Vpower, an ASCII keyboard, and a modified television set ormonitor to have a full computer system with 8K BASIC-in-ROM, 4K user space and a CRT terminal with scrolling.$398.00

Challenger n*P

Our very popular fully packaged BASIC-in-ROM computer.Challenger IIP contains the Model 500 CPU Board with 4Kof RAM, our new 540 32x64 character video display,keyboard and complete audio cassette interface. The unitalso has internal power supplies and a four-slot backplanewith two open slots for expansion. The user has only toconnect a monitor or modified television set to its output,and he is ready to program in BASIC. To store programsand data files, he needs only to connect a conventionalaudio cassette recorder to the built-in audio cassette in-terface. The unit is fully assembled and ready to go.$598.00

Challenger II Disk Systems

The ultimate in personal computing offered by OhioScientific is the Challenger II system with single- or dual-drive full-sized floppy disk. Each floppy stores 250,000characters. The Challenger II is available as a videosystem with keyboard so that all the user needs is a televi-sion or monitor for operation; or as a serial version wherethe user must supply his own terminal. Challenger II disksystems automatically load in BASIC and now have an ex-tensive library of high-performance programs. The pro-grams are ideal for the advanced hobbyist, educationalusers, industrial development and small business applica-tions. Challenger II disk systems are very economical. Forinstance, a 16K disk system with 250,000 bytes of diskstorage starts at under $2000.00

11679 Hayden • Hiram, Ohio 44234

For more information contact an Ohio Scientificdealer or send $1 for our 64-page buyers' guide.

BYTE March 1978

37

The Challenger in

System

When considering cost effective computers for small business applications, theprospective buyer really has only a few choices: Ohio Scientific's factory-assembled fully in-tegrated computer systems, or the multitude of "pot-luck" 100 systems.

First consider the 100 system. It is a computer system defined as a collection.ofS-100 components. It is offered by computer stores and systems houses who mix CPU boards,memory boards, cases, mini-floppies, full-size floppies and numerous software packagesfrom many different vendors. In many cases the components even vary from system tosystem. Unfortunately, what is often used in a computer system is simply what the computerdealer has on hand at the moment. This may include off-brand or obsolete boards, amongother things.

The end user of these pot-luck 100 systems may experience dissatisfaction with thesystem. First of all, all S-100 products are NOT compatible with each other, as is commonlyassumed. The same is true for hardware products, and most certainly for software products.So although the user may be able to get one or more software packages from the dealer alongwith the computer system, it can be a battle from there on converting software to run on hiscomputer.

The second problem is service. If the customer moves or the dealer goes out ofbusiness, the customer is out of luck because virtually no one will service computer systemsof mixed origin. The computer system might even have been built from kits since most S-100manufacturers offer their products in kit form. Several charge outrageous prices for assem-bled products. And then there is future expansion — this can be difficult because all S-100products are not created equal or compatible!

We could go on with this horror story, but let us take a more positive approach andlook at the other alternative — the factory-integrated computer system. Ohio Scientificmanufactures a full line of computers and accessories which are not compatible with S-100equipment, but are fully compatible with our full line of expansion accessories. All of oursystems-level equipment has always been available only in fully assembled form. When youbuy an OSI small business system from a dealer, you are assured of buying a standard com-puter system that was factory assembled and tested. You can be assured of getting servicefrom any of Ohio Scientific's dealers and direct from the factory, now and in the future,whether you stay in your present location or move across the country.

A standardized system means standard software. You can order any of OhioScientific's library of diskettes, put them in your disk drive, and your system will performimmediately. And you can make use of our large dealer-generated software library which runson all Ohio Scientific disk systems. Finally, regardless of the possible pitfalls with other com-puter systems, Ohio Scientific's Challenger II and Challenger III business systems stand ontheir own, based on ultra-high performance and impressive performance/cost ratio. Lookcarefully at the specifications of the Challenger III system on the following page. Compare theadvantages of a factory-integrated and supported computer system with those of a computersystem of mixed origin. We think you will agree Ohio Scientific is the only sensible choice incost-effective small business computing.

• Designed for small business computing.

• Uses the 510 triple processor CPU Board, runs 6502,6800, 8080 and Z-80 programs.

• Available with up to 1 Megabyte of RAM memory; highreliability static RAM is standard; low-cost dynamic RAMis optional.

• Single- or dual-drive floppy disks store 250,000characters per surface — 3 to 4 times the storage of mini-floppies.

• Supports our ultra-fast 6-digit BASIC (see "BASIC Tim-ing Comparisons," Kilobaud, Oct. 1977, p. 23, where OhioScientific out-benchmarks all of our competitors) and ournew super-fast 9-digit business BASIC.

• Powerful operating systems support all standard I/Oports including multiple terminals, line printers, videodisplay and disk.

• Disk supports: sequential, random and index sequentialfiles.

• Applications software, including:

WP-1, a powerful disk-based Word Processor.

DMS, a unique data-base management system whichsupports continuous disk addressing of up to 250,000characters per file.

Complete business packages including AccountsReceivable, Accounts Payable, Ledger, Payroll, Inventoryand Taxes.

• Two factory-supported terminal options and two factory-supported line-printer options.

• Optional 74-Megabyte hard disk for $6000. Reel-to-reelmag tape coming soon.

• Optional 16-user operating system with time share anddistributed processing capabilities.

• Optional rack mounting and rack enclosures.

• Leasing programs and maintenance contracts availablethrough many dealers. Optional nationwide field servicecoming soon.

•Challenger III systems have extremely highperformance-to-cost ratios. For example, a system com-plete with triple processor CPU, 32K bytes of static RAM, aserial I/O port, dual drive floppy disks (500K bytes of on-line storage), fully assembled, plus DOS, BASIC and ademonstration program library costs $3481 fully assem-bled.

• The same system complete with a deluxe upper-lowercase x-y addressable CRT terminal, 65-line-a-minute trac-tor feed line printer and an applications software librarysells for about $6000, or rents for a little over$200 a monthon a three-year lease!

DEALERS

The Abacus

Niies Ret

Berrien Springs. Ml 49103

1616(429-303'!

American MicroprocessorsEquipment & Supply Corp.

20 N Milwaukee AvePrarieview. IL G0069(312) 6340076

Computer Mart ol New York118 Madison AveNew York. NY 10010(212)686-7923

Compuler Place

RD#4

Box 910

Joplin M0 64801

1417) 781-1986

Computer PowerP 0 Box 28193Snn [lingo, CA 921281714) 746-0064

Computer Shop (Alrcom)2W Norfolk St

Cambridge. MA 02139'■617)661'2670

REPRESENTATIVES

Delaware Microsystems92 E Mam Si #1Newark CE 19711(302) 738-3700

Great Lakes Photo. Inc.

5001 Eastman RdMidland. Ml 48640(517)631-5461

H/B Compulers217 Easi Mam SiChariotlesvifie. VA 22903(804| 295-1975

MicrocompP 0 Box 1221Fond-Du-Uc, Wl 54935(414)922-2515

Microcomputer Workshop234 Tennyson TerrWilliamsville, NY 14221[716) 632-8270

Micro Computer World313 Michigan N EGrand Rapids. Ml 49503(616)451-8972

Small Computer Systems4450 Trimly AvenueSalt Lake City UT 84120(801) 967-7635

Abacus Data

P0 Box 276

Oil City. PA 16301

Associates Consultants

33 Ogden Ave

East Williston, NY 11596

(516) 746-1079

BRAG Microcomputers

19 Camondge SI

Rochester, NY 14607

1716)442-5861

Byte Shop

2432 Chesler Lane

ColumOus. OH 43221

(614)486-7761

Computer Business

P.O. Box 171

LaPorte. IN 46350

(219) 362-5812

Custom Computer Systems. I

1823 Lowry Ave.. Norlh

Minneapolis. MN 55411

(612] 588-3944

Johnson Computer

P 0 Box 523

Medina, OH 44256

(216)725-4560

Omega Computing. Ltd.

Box 220 Station P

Toronto. Oni M5S 2S7

(416)425-9200

Pan Atlantic Computer Systems, GmbH

6! Darmstadt

Frankfurterslrasse 78

West Germany

(08102) 3206

Secom Systems

541-1 New Peach Tree Rd

ChamDIee. GA 30341

(404)934-3272

Small Computer Systems

3140 Wadalae Ave

Honolulu HI 96816

(808) 732-5246

Systems Engineering Enterprises

Suite 307

1749 RockviHe Pike

P-ockville. MD 20852

(301) 468-1822

Tek-Aids. Inc.. 1513 Cram Si" Evanston. IL 60202

(312) 328-0110

Total Data Systems

125 Fairway Lane

Fort Collins. CO 80521

(303) 482-6215

Tricomp, Inc.

18 Alameda Square

Denver. CO 80223

(303) 935-1100

Yingco. Inc.

2 World Trade Cnlr

Penthouse 107th Floor

New York. NY 10048

(212)775-1184

11679 Hayden • Hiram, Ohio 44234

For more information contact an Ohio Scientificdealer or the factory. Be sure to specify your interestin business systems.

BYTE March 1978

39

Photo 5: The joystick box which was implemented in order to create thecolor sketchpad application of listing 1. The cabinet is a gourmet plasticfood container obtained at a retail outlet. The box is wired according tofigure 1, which was created using the Apple II documentation.

Continued from page 35

implementing a version of what was called a"Cybernetic Crayon" by Thomas Dwyer,Leon Sweer and Margot Critchfield in anarticle we published in November 1976. Thefirst requirement was that of creating a joy-stick input to replace the separate controlpaddles which are standard from the manu-facturer of Apple II. Then with the joystickbox tested and working, I would create soft-ware which would use the joystick and theApple II keyboard to create color doodleswithin the 40 by 40 matrix of the televisionscreen in the low resolution graphics modeof operation.

The creation of a joystick box with theApple II is a simple matter of wiring. Themanual lists the complete set of signals avail-able at the game IO connector, a 16 pin dualin line socket located near the rear of themain board of the computer. The wiring isgiven in figure 1, showing the essentials oftwo resistance measurements inputs (PDL(O)and PDL(1) in 5 K BASIC) and three switchinputs. The actual box which I created isshown in photo 5. The joystick, which waspurchased from James Electronics, has four100 K potentiometers, of which only twoare used, one on each axis. The switcheswere pushbuttons removed from an archaicsurplus digital test jig (circa 1960 technol-ogy). The entire device was mounted in thebottom of a gourmet food container which Ipurchased retail at a shopping mall for thispurpose. (I actually had to buy a matched

set of three food containers for about $10,of which one was the right size.) The largehole for the lever of the joystick was drilledfirst, after which holes for the four #4-40mounting screws were carefully located anddrilled. (Use of a transparent containerhelped immensely here.) Wiring according tofigure 1 was done point to point aftermounting the push button switches.

Making a Program.. .

The wiring of the actual control box wasderived directly from the documentationwhich came with the Apple II (although itrequired some knowledge of the way a 555style timer is used to measure a resistance bycontrolling the width of a pulse (see May1977 BYTE, page 42, figure 2)). In a similarway, the hook for use of the resistancemeasurements as controls of a program isbuilt into the 5 K integer BASIC which ispart of the Apple II. This hook is the built infunction PDL(x) where x is an integer from0 to 3 corresponding to the four possiblepaddles which may be used. In the case ofthe paddle box of figure 1, only PDL(0) andPDL(1) will give any externally variablevalue when referenced. It is one thing toread the cursor value for a display fromthese inputs, but it is quite another to use it,as I found.

My first attempt was to use the integervalue from 0 to 255 returned by PDL(n) as adirect cursor control for the position of anaction being performed on the screen. Theonly problem here was that when I normal-ized the values to a range of 0 to 39 appro-priate for the 40 by 40 matrix of points ofthe Apple II, the characteristics of mypotentiometers prevented fine control ofwhich point on the screen was addressed(certain points proved totally unadddres-sable). My second attempt was to use atabular transfer function to convert observedvalue to a 0 to 39 coordinate value. Afterthis did not work well, as a final expedient Ithen reduced the joystick inputs to the logi-cal equivalent of a set of four single polesingle throw switches which would input aneffective "velocity" value of -1,0or+1 foreach axis of motion of the joystick. Once Ihad an effective way of input for the cursormotion commands defined by the joystick, Icould begin to design a program to allowdefinition of color values, and depositing ofcolors under control of one of the switchinputs of the control box.

The final program, a result of severaliterations, is given in listing 1, photographi-cally reproduced from the screen of mytelevision display. The program begins withsetting of the "graphics" mode with the GR

40

BYTE March 1978

Subsystem B

Each board is a standout.Together, they're a powerhouse.

In the beginning there were boards,thousands of them.

That's how we started in the business.Making memories and interfaces forother people's computers... and makingthem better.

Now that our own Sol has becomethe number one small computer, youmight think we're putting less emphasison our board business.

Not so.

We're just doing more creative thingswith them.

One neat package gets yourcomputer on the air.

For example, we've built SubsystemB, which ties together five ProcessorTechnology modules into a completelyintegrated system that makes otherS-100 Bus computers work almost aswell as our Sol.

Circle 98 on inquiry card.

Subsystem B includes a memorymodule, three input/output modules,a general purpose memory, andappropriate software.

A specialized software programcalled CUTER knits togetheryour computer and its peripherals tocreate an integrated, smoothlyworking system.

It's the fastest, cleanest way to get online, and it costs less than ifyou bought each module separately.

You get your choice of two lowpower, reliable memory modules in 8Kor 16K capacity.

Our VDMT video display module(still S199 in kit) is the industry standarddisplay device with over 6,000 in use.

Our CUTS high speed, low cost(S110 in kit) audio cassette interface isthe most reliable on the market and issupported by our broad line of cassette

software including Extended BASIC,FORTRAN* PILOT* FOCAL andnumerous others.

And our 3P +S input/output moduleoffers a low cost way to handlevirtually all the I/O needs of any S-100Bus compatible computer system.There are close to 10,000 in the field.Price is just $149 in kit.

Yes, we may have become the makerof the Number 1 small computer —the Sol. But we haven't neglected thequality of our board business. Wecan't afford to... because we use manyof them in our own computers.

For our most recent literature andprice list see your dealer or writeProcessor Technology Corporation,Box B, 7100 Johnson Industrial Drive,Pleasanton, CA 94566. (415) 829-2600.

ProcessorTechnology

* Available soon.

Listing 1: The color sketchpad program, implemented in 5 K Apple BASIC.Showing complete lack of form, this program is written by its author withoutREM statements to explain what is going on. See the text of the article fordetailed comments.

:<"j-> THEN 17!

1678 goto teee «.„_

' PRIHT = PRIHT ■■ PRINT

2828 JF^CM OR COI5 THEH 18*8|PI ^?NIg3;0ft?9I= NEXT I

ft ff*-

If pruBHTii^w ™««-«

2528 INPUT T« .,

2530 gqsub gige

ilSS HSt'WwHT - PRINT ■ PRINTTJ&^I*THEH*320O

PLOT Y,X=X=X-1PLOT Y,X=X=X+1PLOT Y»X=Y=Y-1PLOT Y,X=Y=Y+1

8508 PR

851"851853870

8726 OEP8730 GOT874

NEW COLOR'.SCOL

- PEEK <-'

OSIT<128 T

THEN RETURN

POSIT=0 THEN 8800

■ X<0 THEH X«8F X>39 THEH X=39F Y<8 THEH Y=8F Y>39 THEH Yf39F DEPOSIT THEH 9950

L«= SCRtK Y. X ) : BLNKcLNG■1RNIR«=SC0LT Y.Xi URN

statement, after which a loop contained inline 110 clears the screen to black color with40 HLIN function calls to draw horizontallines across the whole screen with the lastcolor value (set by the statement COLOR =0 in line 100). Lines 120 to 190 then initial-ize several variables. X and Y are used by theprogram as the current cursor values, rangingfrom 0 to 39, initially set approximately tothe center of the screen. DEPOSIT and0DEP are flag values used to coordinatewhether or not the cursor leaves a trail ofcolor. SCOL is used temporarily to storecolor values. LNG is the length of the delayloop which controls how fast the cursorblinks, and must be an even number so thatit can be divided by 2. BLINK is the runningcounter for this delay loop. The joystickdead zone limits are defined with a requestto the user, and are the number of statesbetween 0 and 255 at either end of the rangewhich will be considered equivalent to thenonzero velocity values for the cursor. Withentry of the value 100, the calculation of thedead zone gives nonzero velocity if the inputfrom the joystick measurement is 0 to 100,or 155 to 255 in that direction. With thehardware I built for the external controlbox, a dead zone of 100 is a typical usefulvalue; nonlinearities in the potentiometersmake lower values impossible to use, andhigher values make it very difficult to set thejoystick to dead center and stop motion ofthe cursor. The variables ZD and DZ containthe dead zone limits.

The main routine of the color sketchpadprogram is found in the region from lines1000 to 1070 of the listing. This "executive"loop begins with a small loop that scans forkey input from the Apple ll's keyboard. Thecurrent output of the keyboard is obtainedby the magical incantation on line 1000.Two subroutines are called in this scanningloop at lines 1003 and 1005. The keyboardscanning loop waits until a valid key code(greater than 127) is returned from the key-board before decoding a keyboard command.The subroutine at lines 3000 to 3350 blinksthe cursor and reads the paddle, moving thecursor according to the values XX and YYwhich are input when the BLINK count hasreached zero. The subroutines which imple-ment motion are found at lines 6000, 6500,7000, and 7500.

Returning to the main keyboard scan-ning loop, the second subroutine calledwithin this loop is found at lines 8700 to8820, and is responsible for reading the"DEPOSIT" switch, switch #2, and settingappropriate flags to perform the action ofdepositing a color. Eventually, at line 1010a KEY value of an ASCII character code

42 BYTE March 1978

The Ultimate Turn-on

On/off control everywhere-by computer over the AC wiring

Now it's simple and economicalto control AC devices remotely froman S-100 or Apple II computer.Mountain Hardware's new Introl™system delivers on/off commandsover the existing AC lines — so youdon't have to string a foot of wire!

Control at any AC outlet. The

Introl system impresses a code-modulated 50 KHz control signalon the house wiring. Then decodesthe signal at any outlet to switchAC devices on and off. You cancontrol lights, refrigerators, TVs,solenoid valves, sprinklers, burglaralarms—and many other things weleave to your fertile imagination.With the addition of input sensorsto your computer system, you canautomatically control variables suchas temperature and soil moisture.

Here's how it works. You plugin a single AC Controller board atthe computer bus and connect theAC Interface Adapter to any con-venient 115 VAC outlet. The ACController is now connected toaddress as many as 64 channelsremotely. But it's completely isolated

from the 115v power, so there's nochance of short or shock.

At any outlet where you seekcontrol, plug in a Dual Channel ACRemote. Then plug one or twodevices to be controlled into thebox. Every AC remote has twoindependent 500 watt channels.When commanded by the computer,the Dual Channel AC Remote turnsthe devices on and off independ-ently. When polled by the compu-ter, the Dual Channel AC Remotesends a signal back, telling thecomputer the status of each device.Bidirectional communication pro-vides error free operation.

Simple programming. You writeyour control program in BASIC orAssembler language. Software sub-routines for the control programscome with the equipment — alongwith complete documentation. Ifyou have an S-100 computer, youcan program on/off commands atany day and time using our option-al 100,000 day Calendar/ClockBoard. A self contained powersource assures fail safe operation.

Modest prices. The AC Con-troller, for both the S-100 and AppleII computers, costs $149 in kit formor $189 completely assembled andtested. Each Dual Channel ACRemote costs $99 as a kit or $149assembled and tested. Thus, a fullyoperative system in kit form can beyours for as little as $248.

The Calendar/Clock Board forS-100's costs $179 in kit form, $219assembled and tested.

All prices are f .o.b. Ben Lomond,CA. Prices are USA Domestic. Cal-ifornia residents add 6% sales tax.

Where to find it. The Introlsystem can now be found at compu-ter shops throughout the U.S. andCanada. Drop by and ask for a dem-onstration. Mountain Hardware,Inc., may be reached at Box 1133,Ben Lomond, CA 95005. Phone(408)336-2495

_ ACContn dler (Apple)

^04

M

Dual Channel AC Remote

Circle 75 on inquiry card.

&4 Mountain Hardware

AC Controller (S-100)

BYTE March 1978 43

Photo 6: An example ofanother product of thecolor sketchpad program,in this case illustrating atext tag entered by theprogram's "T" commandto identify when and whodid the illustration. Thecomments on the secondline of the text at thebottom refer to an experi-ment with the program'sjoystick dead zone para-meter.

with a high order bit of "1" is detectedin the range 128 to 255, and the innerkeyboard scanning loop temporarily ends.Input of the KEY is acknowledged to thekeyboard by the magical incantation to thehardware of POKE -16368,0 at line 1015.(All this hardware specific information waselicited from the documentation whichcame with the system.) After the KEY hasbeen acknowledged, its value is checkedand one of five command routines is chosenwith a series of IF statements. If none ofthe valid commands is entered, the GOTO1000 at line 1070 continues execution ofthe keyboard scanning loop looking for avalid command.

Turning to the implemented keyboardcommands of this color sketchpad program,the "F" command is used to fill the screenwith an arbitrary color. The details, foundat lines 2000 to 2060, print a message to theuser "FILL SCREEN WITH COLOR="after which the user enters a value from 0to 15 which is range limited by statementsat 2020. (Thus if "F" is hit by mistake,typing an invalid color value outside therange 0 to 15 gets the user back to themain loop without erasing the current

picture.) If a valid color is indicated, thescreen is filled with that color, erasing allprevious work.

The "C" command is used to accessthe routine starting at line 8500 whichprompts the user for a new color valuewhich will be used for drawing. The prompt-ing message from an INPUT statement is"WHAT NEW COLOR?". As in most BASICinterpreters, the question mark comes fromthe INPUT statement's operation and theactual string found in the program has noquestion mark. The user response to thisINPUT statement at line 8500 is a valuelimited to the range 0 to 15 by the assign-ment statement at line 8510 using the MODfunction.

The "T" command is used to input atext tag contained in the string T$. Thistag is typically output by a reference to thesubroutine at line 2600 prior to resumptionof the scanning loop after a command isexecuted. In the example of photo 6 thetext tag was used to identify the date andtime at which the picture was composed,and the "artist" responsible for it.

Finally, the "J" command is used toreset the joystick dead zone limits in the

44 BYTE March 1978

EDP books you can't afford tobe without

THE INFORMATION SYSTEMS HANDBOOK

by F. W. McFarlan and R. L. Nolan769/29X Pub. Pr., $35.00 Club Pr., $25.50

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766/770 Pub. Pr., $19.50 Club Pr., $14.50

DATA PROCESSING DOCUMENTATION

Standards, Procedures and Applications

by W. L. Harper

767/092 Pub. Pr., $24.95 Club Pr., $19.25

INTERACTIVE COMPUTER GRAPHICS

by B. S. Walker, G. R. Grund and

E. A. Drawneck

767/661 Pub. Pr., $14.50 Club Pr., $12.30

MICROPROGRAMMABLE COMPUTERARCHITECTURES

by A. B. Salisbury

768/03X Pub. Pr., $13.50 Club Pr., $11.40

PROGRAMMING LANGUAGESHistory and Fundamentals

by J. E. Sammett

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THE THINKING COMPUTERMind Inside Matter

by B. Raphael

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GETTING INVOLVED WITH YOUR OWNCOMPUTER: A Guide for Beginners

by L Solomon and S. Veit

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by R. R. Singleton and W. Tyndall

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by W. L. Hunter

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APPLYING MICROPROCESSORSNew Hardware, Software, andApplications

Edited by L. Altman and S. E. Scrupski191/603 Pub. Pr., $15.00 Club Pr., $12.50

MICROPROCESSOR APPLICATIONS MANUAL

by Motorola, Inc.

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MICROPROCESSOR/MICROPROGRAMMINGHANDBOOK

by B. Ward

768/749 Pub. Pr., $9.95 Club Pr., $8.45

ELECTRONIC MUSIC CIRCUITGUIDEBOOK

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Circle 64 on inquiry card.

! Coin?"1*

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The Computer Professionals' Book Club was organized for you, to provide an economicalreading program that cannot fail to be of value. Administered by the McGraw-Hill BookCompany, all books are chosen by qualified editors and consultants. Their understandingof the standards and values of the literature in your field guarantees the appropriatenessof the selections.

How the Club operates: Every month you receive free of charge The Computer Profes-sionals' Book Club Bulletin. This announces and describes the Club's featured book of themonth as well as alternate selections available at special members' prices. If you want toexamine the Club's feature of the month, you do nothing. If you prefer one of the alternateselections—or if you want no book at all—you notify the club by returning the card en-closed with each Bulletin.

As a Club Member, you agree only to the purchase of four books (including your firstselection) over a two-year period. Considering the many books published annually, therewill surely be at least four you would want to own anyway. By joining the club, yousave both money and the trouble of searching for the best books.

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institutional tax exemption status is not appliable to pur-chases made through individual Club memberships. All pricessubject to'change without notice. Otter good for new mem-bers only.

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Please enroll me as a member and send me the two booksindicated. I am to receive the bonus book at the intro-ductory price of S1.89 plus my tirst selection, plus tax,postage, and handling. If not completely satisfied, I mayreturn trie books within 10 days and request that my member-ship be cancelled. If I keep the books, I agree to take aminimum of three additional books during the next two yearsat special Club prices (guaranteed 15% discount, oftenmore). I will receive the Club Bulletin 13 times a year. IfI want to examine the featured selection, I need take noaction. It will be shipped automatically. If, however, I wantan alternate selection—or no book at all—I simply notify theClub by returning the convenient card always enclosed. Iwill always have a minimum of 10 days in which to return(he card and you will credit my account fully, includingpostage, if this is not the case. Membership in the club iscontinuous but cancellable by me at any time afler the four-book purchase requirement has been filled. This ordersubject to acceptance by McGraw-Hill. Orders from outsidethe continental U.S. must be prepaid. Company, business, or

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P39330

BYTE March 1978

45

event that the first value entered duringinitialization was inappropriate.

Summary of the Apple II

As noted at the beginning of this review,I was very enthusiastic about the prospectof this machine from the first word of itsexistence. To be sure, there are minorannoyances with this product in its presentstate, like the mechanical problems withrespect to its case and keyboard mounting,and the persistent problems of radio fre-quency interference which I found usingmy particular color television set as the

primary display. But such problems areminor compared to the achievements ofthis design.

Apple II is a well executed exampleof the way a personal "appliance" computershould be made circa 1977. It is suitedfor the relative beginner who knows BASICbut does not know hardware design, as wellas for the advanced hacker who feels noqualms about using the system's docu-mentation to create custom peripheralsfor the system. For the user who wantscolor graphics, the Apple II is the onlypractical choice available in the "appliance"computer class."

BYTEs Eogs

A Flop in the Floppy

The drafting bug has bitten BYTE.The accompanying figure detail (takenfrom figure 1a of David Allen's article,"A Floppy Disk Interface," January1978 BYTE, page 61, right-hand side)contains a number of drafting errorsinadvertently included during the pro-duction of the article. The correctionsare circled. In addition, ICT 8c, a threeinput AND gate, was incorrectly drawnas a NAND gate, and the A1 and A2

Clock Stops

I enjoyed M F Smith's article in theNovember 1977 BYTE on "UsingInterrupts for Real Time Clocks." Hedid a great job in describing how todevelop and use a real time clock. So Iimplemented his program on my AMIPROTO 6800 System, only to find itnot functioning properly in updatingthe clock. After examing the programlisting closer, I found the bug at line29 of your listing on page 53. The indexcompare was only index by 7 into theconstant table, it should be index by8. After I made this change everythingworked."

William W Barncord

Burroughs Corporation

2473 S Memphis Way

Aurora CO 80013

Joystick Gets Stuck

This letter is in reference to "AnInexpensive Joystick Interface," whichappeared in the March 1977 BYTE onpage 88. I'd like to congratulate TomBuschbach on a fine article, but thereseem to be several mistakes in theschematic.

On the MC1408L-8, A1 is the mostsignificant bit. The schematic shows thisconnected to the least significant bit ofthe counter. The eight digital inputs tothe digital to analog converter should bereversed in order to obtain a propersawtooth output.

Also, on IC2, 74193, the count upinput is shown grounded. This must beheld high to enable the count downinput.

I have constructed this circuit using adifferent register chip (8212) and theabove changes, and it works verynicely."

William Lemiszki424 Cambridge StAllston MA 02134

inputs of IC22 should be shown con-nected together. Our thanks to thereaders who spotted these errors, andour apologies to David Allen."

Fractured Factors andWalsh Function Bugs

William Jackson's letter on page 172of the October 1977 BYTE contains twoerrors which can be corrected by re-placing the fourth equation with:

=(y+z)+j(x-z)and the fifth equation with:Where x=(a+b)c.

Regarding the September 1977 arti-cle "Walsh Functions: A Digital FourierSeries": in the third paragraph on page196, one reads "Sin (11.25°) = 0.09802."The proper value is 0.19509. The valuegiven is that appropriate for 11.25/2°.The sums should be, I think, 5.13842,-2.13578, -0.40974 and -1.03218in table 4. The coefficients would thenbe 1, -0.4156, -0.0797 and -0.2009.Also the signs for SAL(7) at the bottomof the table should be PNPNNPNP.What was printed is CAL(7).

If I have not made a mistake, theresistors in table 5 would be unchanged,but shouldn't there be some differencesin the circuit diagram?

J S Lefson

6609 Cote St Luc Rd, Apt 203

Montreal, Quebec

CANADA H4V 169

Dr Jacoby replies:

Mr Lefson is correct that SAL(7)in table 4 is misprinted. This can beeasily seen by comparison to table 3 orby knowing that the SAL functionsthemselves are odd about their centersand even about their I j4 and 3/4 periodpoints, and thus should give identicalvalues to the left and right of center intable 4.

In addition, the values for Sin 78. 75°and Sin 101.25° are incorrect and shouldread 0.98078. I believe that the valuesfor the sums are correct as given as wellas the circuit connections [compare tofigure 3 for SAL(7)]. One point of con-fusion here might be the signs of thecoefficients, since they take into accountthe inverting op amp configuration andthus appear re versed. ■

46

BYTE March 1978

Application Software!

You canbuy softwarefrom anybody -

but ours worksin your system.

We only sell one product,Quality.

We have been in business for over nine years building a reputationfor providing a quality product at nominal prices — NOT what thetraffic will bear. Our software is:

• Versatile — as most programs allow for multiple modes ofoperation.

• Tutorial — as each program is self prompting and leads youthrough the program (most have very detailed instructionscontained right in their source code).

• Comprehensive — as an example our PSD program not onlycomputes Power Spectral Densities but also includes FFT's,Inverse-transforms, Windowing, Sliding Windows, simul-taneous FFT's variable data sizes, etc. and as a last wordour software is:

• Readable — as all of our programs are reproduced full sizefor ease in reading.

• Virtually Machine Independent — these programs are writtenin a subset of Dartmouth Basic but are not oriented for anyone particular system. Just in case your Basic might notuse one of our functions we have included an appendix inVolume V which gives conversion algorithms for 19 differ-ent Basic's; thats right, just look it up and make the sub-stitution for your particular version. If you would like toconvert your favorite program in to Fortran or APL or anyother language, the appendix in Volume II will define thestatements and their parameters as used in our programs.

Over 85% of our programs in the first five volumes will execute inmost 8K Basic's with 16K of free user RAM. If you only have 4KBasic, because of its' lack of string functions only about 60% of ourprograms in Volumes I thru V would be useable, however theyshould execute in only 8K of user RAM.

All of our programs are available on machine readable media. Forthose that have specific needs, we can tailor any of our programs foryou or we can write one to fit your specific needs.

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BYTE March 1978

47

Continued from page 12

> Voice 2 V"3

*BAR*TIME 4,4

*STOPS VIOLA-8,VIOLA-4;FLUTE-8*TEMPO 4,1002L,4C;2N,4C-

.4N,3A,3F;4N,3G,3E,2N,3F,3D*BAR

Listing 1: The musical example of figure 5 written in the MUSIC language. "Normal" meansthat there is to be a slight pause between notes. "Legato " indicates a smooth transition with nogaps.

VOICE I: VIOLA 8',4VOICE 2: FLUTE 8'(M.M. «l - 100 )

Figure 5: An example of how musical notation is represented in the MUSIClanguage.

The Music Editor

An editor is a program that allows a userto easily create and modify files (which ofcourse may be programs). The Music Editoris a program that allows composers to graph-ically create and modify MUSIC languageprograms. The Music Editor is written inAltair Extended BASIC 4.0 and runs on theAltair 8800b system using a Magnavoxplasma display terminal.

At the simplest level, the editor allowsthe user to type in and alter statementslike any text editor. It also permits the userto copy or move blocks of statements. Theeditor verifies the syntax of each statemententered.

At a higher level, the editor can be usedto graphically display and edit data state-ments. When entering this level, the editordraws the staves. If an existing data state-ment is to be altered, the notes of this datastatement are drawn; otherwise the staves

will be empty, awaiting the input of a newdata statement. The user edits a data state-ment by moving a cursor about the stavesand entering commands. Special macro-likecommands permit the user to create andcopy chords, delete events and insert newones. Upon leaving this higher level, a datastatement in MUSIC is derived from thegraphic display of the staves and insertedinto a scratch file. Photo 3 shows what agraphics editing session looks like to theuser.

Object Language

The MUSIC language is compiled intocode for a "make-believe" machine, onewith a simple set of instructions. Thus wecan say that the object language is in pseudo-machine code. Each object language instruc-tion is two 8 bit bytes in length. The firstbyte in each instruction is interpreted as anoperation code (op code); the second byte isused as a data parameter. There are threeclasses of object language instructions: setport, wait, and repeat.

Op codes with values of 0 to 253 areinterpreted as set port instructions. Forexample, 27-3 means turn on the right-mosttwo bits in port 27 (since 3=00000011 inbinary). These instructions cause the databyte to be deposited in the port numbergiven by the op code itself (each latchingport has a unique address). The bit patternof the data byte specifies which pipe valvesattached to that port are to be opened andwhich ones are to be closed. The pipevalves will remain in that state until theyare reset by another set port instruction.

Repeat instructions (op code value of 254)are trapped by the master system. The masterprocessor handles repeats by retransmittingparts of the object program to the slave

48

BYTE March 1978

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BYTE March 1978

49

Photo 3: The authors' Magnavox plasmadisplay terminal during an editing session.Notes and chords can be created or modifiedby moving a cursor to the desired position.Entire musical phrases can be copied ifdesired. Chords or whole measures thatrepeat need be entered only once.

Listing 2a: An exampleof how the program inlisting I is compiled inMUSIC. The first stepis error checking, fol-lowed by the pro-duction of interme-diate code for eachvoice.

Voice 1

48 The note 4C is 48 half tones up from Co

-3000 A legato half note gets a timing of 3000 units

48 This is the second C

—2400 Timing for a normal half note

—600 Pause after a normal half note

Voice 2

45 This is 3A

41 This is 3F

— 1200 Timing for a normal quarter note-300 Pause

43 This is 3G

40 This is 3E

— 1200 Timing for a normal quarter note-300 Pause

41 This is 3F38 This is 3D

—2400 Timing for a normal half note

-600 Pause

14

27

28

255

27

28

255

1

3212 I

48

° }0 I

12

C from Voice 1 on 8 ft violaC from Voice 1 on 4 ft viola

The F-A chord in Voice 2 on 8 ft flute

Wait for 480 ms

Clear the chord in Voice 2

Pause 120 ms (space between chords)The E-G chord in Voice 2 on 8 ft flute

Listing 2b: Here the com-piler combines the voicesin listing 2a to producethe final object code.

processor as specified by the data byte ofthe repeat instruction.

The wait instruction has an op code valueof 255. The second byte of the instructionis interpreted as a nonnegative integer. Thisbyte's value fixes a delay period computedin 10 ms units. For example, 255-60 meanswait 600 ms.

An object program consists of a seriesof "frames." Each frame contains zero ormore set port instructions and is terminatedby a wait instruction. A frame is executedby the slave computer by first executing allset port instructions in a frame almostsimultaneously. The set port instructionscause some pipes to be turned on andothers to be turned off. If a particular portis not addressed by any set port instructionduring a frame, this port's pipes remain intheir current state. This new pipe statelasts for the duration given by the frame'swait instruction. At the end of this duration,the next frame's execution begins. Thuseach frame causes a combination of pipesto be played for a set length of time. Anexample of an object program is given inlistings 2a and 2b.

The execution of the object program iscontrolled by two performance programsthat couple the master and the slave compu-ters together. There are two reasons why wedecided to use a pair of computers to handlethe performance of the music: one, thecorrect latching output ports were alreadyavailable on the Intellec, and, two, theslave could handle all the real time demandswhile the master handled the retrieval andloading of "pages" of the score from thediskette. (A page is defined as 256 bytesof object code.)

The slave microcomputer's memory actsas a circular buffer. The master initiates anobject program execution by sending a

50

BYTE March 1978

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The combined hardware/software/lab manual includes10 experiments.

The ROM based speechrecognition program occupies2K bytes of ROM.

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INC

BYTE March 1978

51

header message to the slave. The masterthen waits for a Block Request (BR) message.At the receipt of each BR message, anotherpage (256 bytes) of the object program issent to the slave.

After receiving the header message, theslave sends enough BR messages to fill itsmemory with object code. After receivingenough pages or an end of program instruc-tion, the slave starts executing the objectprogram. After finishing one page of objectcode, the slave sends out a BR message.The next page sent is placed in the spacereleased by the previous page that wasexecuted. The execution of the object pro-gram and the refilling of the buffer pro-ceed concurrently.

After sending the entire object program,the master processor ignores all furtherBlock Request messages. When the slaveexecutes the end of program instruction(which is a WAIT instruction with durationzero), it sends a completion message backto the master processor. The master proc-essor can then inform the user that the slaveis ready to accept another program.

This performance system software consistsof two programs. The "slave" program iswritten in Intel 8080 assembly language.Its machine code representation is storedon read only memory in the slave micro-computer. The "master" performance pro-gram is written in Extended BASIC 4.0 forthe Altair 8800b computer.

The Compiler

The compiler accepts a MUSIC languageprogram and outputs an annotated listingfile. If no errors are detected, an objectprogram is then generated and saved on adiskette as a file. Thus the compiler's workcan be divided into two phases: error check-ing and code generation.

The error checking consists of two typesof operations: syntax verifying and contextchecking. A syntax verifier examines eachstatement to insure that it conforms to therules of the language. For context commandsit checks for correct number and types ofarguments and correct placement of thisstatement in the measure. The repeat com-mand's arguments and placement are checkedand the nesting of these statements is veri-fied. Data statement arguments are checkedfor syntax correctness.

In addition to syntax, the context correct-ness of data statements is checked. Thenumber of data statements in a measuremust equal the number of voices currently

active as declared by the last STOPS com-mand encountered in the program. Theduration of each data statement must equalthe measure duration as declared in thecurrently active time signature. This checkingis a real help to the composer since it handlesall the petty details.

The code generation phase of the compileris divided into four operations: generatingrepeat instructions, handling context com-mands, processing data statements, andcoordinating measures.

Each repeat command causes one objectcode repeat instruction to be generated.Repeat instructions cause all the databetween HEAD and TAIL commands to beused twice.

The context commands serve a functionsimilar to declaration statements in con-ventional computer languages. Their mainfunction is to alter the values of the globalarrays and variables that determine the noteaddress and note timing calculations. A noteaddress is a number that relates a note to apipe, while a timing determines how manymilliseconds the associated notes are to beheld.

The data statement handler processesthe data statements to determine the notesto be played for a particular measure. Eachvoice has its own First-In-First-Out (FIFO)queue for storing information about theevents of the current measure. As eachevent in a voice's data statement is proc-essed, its FIFO queue is filled from the topdown. First the notes of the event, then theduration of the event, and finally the dura-tion of the pause between this event andthe next one are placed on the queue. Atthis stage, note values are stored as integernumbers representing a number of semitonesabove a base pitch, without regard to stopsettings. The durations are computed inbasic time units regardless of the currenttempo setting. The durations are stored asnegative numbers in order to distinguishthem from note values. Figure 6 showsthe general format of a queue for one voice.It represents a sequence of four chords witha rest between the last two.

In this example there is no pause durationbetween events 2 and 3, indicating that event2 is played legato with event 3. Event 4 hasno note values, therefore it isarest.Glissandosand tremolos are treated like event macros.They are translated into a series of eventsby the data statement parser before they areprocessed onto the queue.

After each voice in a measure has been

52

BYTE March 1978

parsed, the voice coordination routine gene-rates the object code using the followingalgorithm:

1. The duration counter for each activevoice is set to 0.

2. The duration counter for each voice isexamined. Those voices with a zeroed dura-tion counter have their top sequence removedfrom their queue for processing. (A sequenceis all the information from the top of thequeue down to and including the first dura-tion of pause found.) The sequence's durationis stored in the voice's duration counter.

3. The voice's bit map is cleared. (The bitmap is an array of bits where one bit is usedto represent the state of one organ pipe.) Aseach note value of a voice's sequence is proc-essed, it is expanded into as many noteaddresses as the number of stop settingsdefined for that voice. Each note addressgenerated causes a particular bit in thevoice's bit map to be set to 1.

4. All the voice bit maps are ORed into amaster bit map.

5. The master bit map is compared to theprevious master bit map.

6. Those output ports whose bit patternhas changed generate set port instructionswith the port's new bit pattern as the databyte of that instruction.

7. To generate the wait instruction, theduration counter for each voice is examinedand the minimum duration is found. Thisminimum duration is subtracted from eachvoice's duration counter.

8. The minimum duration is multipliedby the tempo variable to yield the actualtiming of the object code frame produced. Ifa frame is within an accelerando or ritardpassage, the timing is altered to reflect thegradual change in tempo, the tempo variableis updated, and the duration remaining inthe tempo changing passage is decremented.The final actual timing is used to produce aWAIT object code instruction.

9. The current master bit map is labeledas the previous master bit map.

10. The routine now goes back to step 2if all the queues are not empty; otherwisethe next measure in the MUSIC languageprogram is processed.

The queues should empty simultaneouslysince each voice's data statement shouldhave a duration equal to the one set by the

time signature. (This is checked duringphase 1 of the compiler.)

The above algorithm was designed to com-pile multivoice music efficiently. An impor-tant feature of this algorithm is that itallows more than one voice to share thesame rank of pipes. In addition, it permitsthe user to generate from each note speci-fied many pitches through the stop settingmechanism. Since the stop settings are per-formed through software, a user can trans-pose each note of a voice any number oftones and into any rank of pipes. Listings 2aand 2b show how the above algorithm worksfor the simple two voice example given infigure 5.

Future Plans

While the system described here is notmeant to compete with large dedicated musicresearch systems, it nevertheless has severaladvantages over a number of other computercontrolled music systems. Currently, wehave two ranks of pipes with 64 pipes ineach rank. However, additional ranks ofpipes could easily be added to the system.Each 64 pipe rank requires only eight morelatching output ports. The theoretical limitfor an Intel 8080 based system is over 2000pipes. Microcomputers that use memorymapped IO could conceivably controlhundreds of thousands of pipes.

The system can be extended to othermusical instruments. By using solenoids,any keyboard instrument can be controlledthrough the output ports. Alternatively,the solenoids might be placed inside theinstrument, driving something like the jacksin a harpsichord directly. To play the harpsi-chord along with the organ would just requirethe addition of a harpsichord stop to theMUSIC language.

Electronic synthesizer music is not incor-porated in our system because of the highcost of the special hardware needed, but atleast three low cost analog output boardsdesigned for Altair (S-100) bus microcompu-ters have recently been announced. It seemsreasonable to expect that the MUSIC lang-uage could be applied to these new pieces ofhardware.

The voice concept has some applicationto "synthetic" music composition becauseit allows the user to create new timbres byspecifying nonstandard overtone ranks (eg:

BYTE March 1978

53

chord

chord

chord

5 note \note \note (

i noteI note| noteduration ,

chord

event 1

event 2

event 3

event 4

event 5

Figure 6: The general format of a queue forone voice used in the MUSIC language.

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a 3.1416 foot flute). By assigning dummystop settings to certain voices, the composercan also isolate the effect of these harmonicsduring a test performance.

We are planning to eliminate the need tocompile and save object programs. An assem-bly language version of the compiler is beingwritten that will interpret MUSIC languageprograms in real time. This will be done bysending the bit pattern computed in step 6of the measure coordinating routine to thedesignated output port and use the timevalue generated in step 8 to set an intervaltimer. This new software system will allowa user to interact with a performance. Wealso hope to build a subsystem to capturekeyboard performance and translate it intoa MUSIC language program.

Aside from musical application, the pro-grams written for this system can be usedas a realistic basis for explaining manyimportant concepts of computer sciencein a context that removes much of themystery surrounding computing. In manyways, this could be the most useful contribu-tion of the music system, suggesting as itdoes that the teaching of complex ideashas much to gain from a liaison with thecreative arts."

A Glossary of Some Musical Terms

Accelerando: A direction telling the musician tomake the music gradually faster (increase tempo).

Bar: Vertical line on the musical staff separatingthe measures of music. Sometimes used as asynonym for a measure.

Glissando: A rapid sliding up or down the musicalscale.

Key Signature: The sharps or flats placed after amusical clef to indicate the key.

Legato: A direction telling the musician to playin a smooth and connected manner.

Ritard: A direction telling the musician to makethe music gradually slower (decrease tempo).

Semitone: The interval between two tones in thechromatic (well tempered) scale (ie: the distancebetween Ai> and A is a semitone).

Staccato: In a broken or clipped manner.

Tremolo: Effect produced by the rapid repetitionof a note.

54

BYTE March 1978

Circle 85 on inquiry card.

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Circle 37 on inquiry card.

BYTE March 1978 55

Jef Raskin

POB511

Brisbane CA 94004

The

Microcomputerand thePipe Organ

Photo I: Pipe organ con-sole shown in the home ofthe author's colleague, JimBrennan, who did the cus-tom Installation work. Theconsole was obtained froma church in Pasadena CA.

One night I got a call from a man whohad been wandering through the personalcomputer stores in the area. He was lookingfor a computer to operate his huge pipeorgan. Inevitably, he was given my phonenumber, since I had been going around tothe same stores telling everyone that I wasworking on a controller for my pipe organ.

There are several gimmicky reasons forwanting to attach a computer to an organ.My reason is that the combination can pro-vide the performer with a more flexible,easier to play instrument. And then there areall those gimmicks. As it turns out, using amicrocomputer can be less expensive thanconventional console wiring. Before we getinto the subject too deeply, the "organiza-tion" of the king of instruments should bemade clear.

The performer sits at the console. Theperformer's hands rest on one or more key-boards called manuals. There are usuallyfrom two to four manuals. The feet play ona set of keys placed beneath the bench calledthe pedals. On most organs since the late1800s, the console is separate from the restof the instrument and is connected to it bymeans of electrical cables. As with the com-puter, the console is the "command center"of the instrument. In addition to the key-boards there are a number of other controlson the console that will be discussed later.

Blockflotes and Zimbels

The sounding portion of the organ con-sists of many pipes. Each pipe sounds one

note. There are typically many differentpipes for a given note, each of which has adifferent sound quality or timbre. A set ofpipes, all of similar timbre, one for each keyon a manual, is called a rank. Each rank hasa name, many of which are hallowed bycenturies of use. Some, like diapason (diapay zen) or bourdon describe sounds thatare characteristic of organs and nothing else.Others, such as trompette or blockflote arereminiscent of trumpets and wooden flutes,respectively. Obviously one rank is a min-imum for an organ. (Renaissance portativeorgans had one rank.) A small organ usuallyhas three or four ranks, controlled from twomanuals. The one being installed in myhouse has 26 ranks. A large organ will have70 or more. The organ owned by my friendmentioned above has 140 ranks. That is verylarge, and only a few cathedrals have more.

Each rank has 61 pipes, as there are 61notes on a manual. Thus for a pipe organ ofa 100 ranks there are 6,100 pipes. Each rankis turned off or on by a knob or switchlabelled with the rank's name. These knobsare called stops. (The terms stop and rankare sometimes used interchangeably, but inthis discussion rank will refer to a set ofpipes, and stop to the controlling knob.)

A large organ often has four manuals(named great, swell, choir and echo or posi-tiv) each having 61 keys, a 32 note pedal-board, 100 or so stop knobs, and a fewdozen assorted controls. Thus there areabout 500 controls that the organist mustmanipulate: a complicated instrument,indeed.

56

BYTE March 1978

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Circle 52 on inquiry card.

BYTE March 1978

57

Photo 2: A view of threeranks of organ pipes in theliving room, including aRauschepfeife, left, Holtz-regal, center, and Umbelbass on the right. Eachrank has its own particulartonal color.

Key Decisions

And now we come to the microcomputer.It must keep constant watch on 500switches and control some 6,000 relays, onefor each pipe. It must never miss a switchclosure or release, and must operate thecorrect pipes (sometimes dozens simul-taneously) within 1/20 of a second. Is thiswithin the capabilities of an 8080? As ithappens, it is. But not without a bit oftricky IO design and some swift algorithms.

For completeness, it should be mentionedthat some ranks are not exactly 61 notes."Unified" ranks often have 75 pipes, andsome special ranks have fewer than 61. Butfortunately these exceptions are easilyhandled. The problem is simplified in someorgans (a little) by sets of ranks grouped into"straight" chests. Instead of each pipehaving its own electrically operated valve(a "unit" chest), each rank in the chest hasa valve. Then all notes of the same name(such as all Cs or all F#s) have one valve.This loses some generality, but requiresfewer valves and electrical connections. ForM ranks of N notes each, a "straight" chestrequires M+N valves. A "unit" chest hasMxN valves.

Organs also traditionally have couplers,which operate either within a keyboard orbetween keyboards. An intermanual couplerhas the effect of operating a note on onemanual when you press the correspondingnote on another. (On some old organs bothkeys actually move when you press one ofthem. This may have given rise to "phantomof the opera" stories.) A coupler that works

within a keyboard plays a note typically oneoctave higher or lower than the key you areplaying, but on the same keyboard. Intervalsother than an octave are also available onsome organs.

An organ is also separated into divisions.These have the same names as the manuals:typically, great, swell, choir, echo andpositiv. The pipes played by the pedals formanother division: the pedal division. Eachrank belongs to exactly one division. In thetraditional organ, a manual can play pipesonly in its division. You can couple manualstogether, but it is impossible to play a rankin the swell division from the great manualwithout playing all stops that are pulled inthe swell division from the great manual.This separation into divisions has no musicalbenefits, but is done merely to simplify theconstruction of the switching in the console.By means of a microcomputer, divisions canbe eliminated. The organist can then inde-pendently assign any rank to any keyboard.This is the first of a number of nongimmickimprovements that can be appreciated byany organist.

The switching in the traditional organ isdone by the most incredible collection ofelectrical, mechanical and pneumaticswitches imaginable. That it works at all,being made mostly of slats of wood andstrips of leather with silver wires for con-tacts, seems miraculous. It is not surprising,then, that freedom in interconnection hasbeen restricted in the past.

The wiring from the console to the pipesover distances from ten to over 100 feet

58

BYTE March 1978

1&*"

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asSS**

0s-

,op°:

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Circle 114 on inquiry card.

BYTE March 1978 59

reminds one of a cross between the innardsof a computer before the mother board wasinvented and a telephone company switchingoffice. A major advantage of the computer-ized organ is the elimination of most of thiswiring. In a very large organ, the cost of thecomputer system may be less than the costof the cabling alone.

When an organist plays a piece, it has acharacteristic sound quality produced by ajudiciously selected set of stops being acti-vated. A particular collection of stops iscalled a registration. It is usually desirable tobe able to store such combinations. Thereare a number of buttons called pistons whichrecall combinations of stops. Logicallyenough these collections of stops are calledcombinations or presets. There are often afew fixed presets, and a number of pistonsare provided whose registration the organistcan change at will. Another advantage ofthe computer controlled organ is that manymore presets are available. 4 K bytes ofmemory can store hundreds of differentpresets, more than on any conventionalorgan. This amount of memory costs lessthan one preset done mechanically! Andit's a lot easier to install.

Consider what happens when a single keyis pressed. First, any keys that are coupledto it are also activated on its keyboard aswell as on other keyboards. For each ofthose resultant keys, as well as the originalkey, the applicable stops must be looked up.If there are two couplers and four stopsactivated for each of the three keyboardsinvolved, no less than 12 pipes must sound.When playing a full chord with manycouplers and stops engaged, it is not un-common for 500 pipes to be operatedsimultaneously.

Getting Organized

A number of schemes were concocted fordriving the pipes and reading the keys. Onescheme, which has been used on smallerorgans for computer control, was to haveeach key send out a unique code. Each piperecognizes its own address. The computerwould receive key codes as well as stop andcoupler codes, and compute the appropriatepipe addresses. A decoder at each pipe, aswell as a diode matrix or other encoder forthe console, would be required. Since on alarge organ there are over 2'2 pipes, even a12 bit code would not be long enough.This would mean assembling two 8 bitwords for each pipe. Putting out over 500of these in 1/30 of a second (consideringthe number of steps required in the pro-gram) would have been impossible. Further,the cost for decoders at each pipe is

prohibitive. This ruled out going to a 16 bitcomputer, since it wouldn't help the decoderproblem, and a larger word size seemed tohold few advantages in any other way.

Cost alone ruled out the brute forceapproach of using a very fast computer.Another way to get high data rates from amicrocomputer would be to use directmemory access (DMA) circuitry. With thisscheme one DMA device scans the keyboardcontinuously and enters key depression andrelease information into memory. The mainprocessor (at its own rate) scans the key-board image in memory and constructs a listof pipes to be played or quieted. AnotherDMA scans the list of pipes and controls thepipes accordingly. In essence, three com-puters would share the same memory andwould run asynchronously, each going asfast as conditions allowed. This seemedfeasible, and is necessary for larger organs.But for smaller organs the DMA is notneeded, as will be seen.

Part of the solution lay in hardware. Atone extreme of decoding (as explainedabove), each pipe has its own decoder. Itwould be more efficient for each group of,say, eight pipes to have a decoder which de-tects its code and then accepts the next byteas controlling eight pipes in parallel. The 8bit control byte 10001001 would mean thatthe notes C, E and G are to be played, whileleaving C#, D, D#, F and F# silent. Thiswould reduce the number of decoders by afactor of 8, and then operates eight pipesat a time. This was fast enough in the IOdepartment, but the time required to as-semble the control bytes by masking orrotation was too great. A microcomputerhandles bytes with great efficiency, butmanipulating individual bits takes signi-ficantly more time. A number of algorithmswere considered, but it was apparent thatthey were not suitable.

At the other extreme from a decoder foreach pipe is the idea of having no decoderswhatever. This idea was put forward early inthe design effort, but was discarded as ridic-ulous. In the end it became clear that theidea was not only feasible, but fast andcheap to implement in hardware. It alsomade the software much easier to design. Itworks like this: A very long serial-in/parallel-out shift register is made. It will have at leastone output for each pipe. Using available8 bit shift registers, the 140 rank organ's2000 electrically operated valves requireabout 250 shift registers. (The 7000 pipesrequire only 2000 controlling lines sincemost of them are on straight chests.) Ineffect we build a 2000+ bit shift register,a long "tube" through which 1s and

60 BYTE March 1978

The Dumb Terminallets you put il all together.

With the new/lower-priced Dumb Terminal™ Kit, that is.Pick one up and escape, once and for all, the headachesof scavenged teletypes and jury-rigged TV sets. With justa little time and aptitude, you can have a live and workingDumb Terminal right in your own home, garage, orbusiness. One that lets you get it all out of your system— or into it.

Forget the cheap imitations, with their overblownprice tags and interminable lists of options. Withthe Kit, you can build yourself the same, oldbasic Dumb Terminal that's been selling over1500 units a month. With basic, sensiblefeatures like a bright 12" diagonal screen.Fifty-nine data entry keys. 1920 charactersdisplayed in 24 rows of 80 letters. Plus 33positive action switches that let you activatefunctions like 1 of 11 different baud rates, anRS232C interface, or a 20mA current-loop.And more. Not bad for Dumb

All you need, besides the Kit, issome initiative, and a few basictools — a good soldering iron,wire cutters, needle-nose pliers,and one or two trusty screw-drivers. The Dumb TerminalKit provides you with every-thing else. Including anattractive cabinet, CRTscreen, keyboard, PCboard, and all essential

electronic components. Naturally, you also get illustrated,step-by-step assembly instructions, not to mention aneasy-to-understand operator's manual.

So, if you'd like more input on the Dumb TerminalKit, just fill out the coupon and we'll send you complete,free information.

Oh, and by the way, just by sending in the coupon,you will be made a charter member of the DumbTerminal Fan Club. A select organization that willsend you your own nifty Dumb Terminal FanClub Kit, containing: an official certificateof membership; an autographed photo of theDumb Terminal himself; and a bona fidemembership card to prove irrefutably you're"One of Us'.' (Sorry, limit one kit per person.)And, if you include a trifling $6.00, youcan have your very own Dumb TerminalT-shirt. (No limit at all on these.)

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Os flow in single file. When all the 1s and Os(standing for pipes sounding or silent) reachtheir correct positions, a command (strobe)is sent operating all the pipes at once. If theprocess is to take 1/60 of a second, the shiftregister has to move 2000 bits in that time.But this is a rate of 120,000 bits per second(120 kHz) which is within the capabilitiesof the shift register and the computer buta bit beyond an unaided 8080. Rememberthat these calculations are for a mammothsize organ. Most organs are significantlysmaller and the problems are correspond-ingly easier.

A similar approach is used for the key-boards. There exists a 33 input parallel toserial converter made for electronic organs.Just two of these integrated circuits wouldsuffice to encode an entire manual. The 500

Photo 3: Another view of the organ showing the swell chest and echo chest.

controls could be transmitted serially to thecomputer in 1/200 of a second at 100 kHz.The interface would require fewer than 20"critters." Again, this is for a huge organ.My own home organ would require only tenintegrated circuit chips for its console.

The hardware for a large organ can nowbe summarized. A 500 bit parallel to serialconverter for input, a 2000 bit serial toparallel converter for output, one input portand one output port are required. Each pipealso needs a power transistor to handle the0.5 A at 14 V required by the valves (thisis a typical figure). Some of the larger pipesmight require two stages or a Darlingtonpower transistor, but there is no real diffi-culty in the design. Another side benefitaccrues at this point: Many pipe organs useelectro-pneumatic valves for each large pipe.This is because an all electric valve openstoo suddenly. To solve the problem, thetraditional builders designed the electricalvalve to let air into a small bellows which,in turn, operates the valve that lets air intothe pipe. A pair of resistor-capacitor (RC)networks and a diode in the base circuit ofthe power amplifier for each pipe can givethe desired slow attack and release usuallyobtained by the much more expensive andproblematical pneumatic system. This canamount to savings of over $1000 in a largeorgan. It should be mentioned that someorgan manufacturers have been successfulin making satisfactory all electric valveswith appropriate attack and decay curves.They would not require the RC networks.

Software design was as gradual as thehardware design. There were two break-throughs necessary before it was clear thatthe 8080 could work quickly enough. (Whenthis design was being done, by the way,the Z-80 and other faster processorswere not yet in production.) But the con-straints of the 8080 and the very large organforced a much tighter and more clever designthan would have been developed if we hadhad more powerful computers and a smallerorgan. Given the newer computers, ofcourse, larger and more complex pieces ofequipment can be controlled. Many indus-trial plants have fewer than 200 sensors and2000 elements that need to be operated inreal time. A microcomputer using the tech-niques outlined here could handle them.

The program begins by sweeping in theconsole settings. To save time only one bitper word is used. This wastes 7/8ths of 500words, but memory is cheap. The same trickcan be used in output, eliminating the neces-sity to pack bits into bytes. Thus over onebyte per key and one byte per pipe will besacrificed to gain speed. That amounts to$40 at most in memory costs. It buys us

62

BYTE March 1978

Computer Mainframe System

First in the TEI family... The MCS-112 and 122 Mainframe Systems.

The Base on Which to Build*

The cabinet

A heavy duty, precision formed cabinet of finecraftsmanship. Completely machined andready for assembly The exterior is fin-ished in TEI blue. Vented for mostefficient thermal character-istics. Furnished with allnecessary hardware.

The front panel

The front panel is blankexcept for an indicating ACswitch and a reset switch.However, the chassis and motherboard are designed so that you mayremove the front panel and insert an IMSAIor equivalent-front panel.

Specifications

MCS-112

MCS-122

Dimensions 17Vi Wx12Dx7'/i H

Power +8volt DC 17 amps

Power ±16 volt DC 2 amps

17'AWx19'ADx7'/4H30 amps4 amps

, The motherboard

An S-100 Bus system high quality mother board with 100-pin edge connectors. Compatible with IMSAI, MITS,CROMEMCO, TDL and other S-100 bus configured circuit boards. Plug connections for reset switch. Voltage terminalsare screw type to power supply leads. All card guides are provided. 12 slots for MCS-112 model and 22 slots forMCS-122 model.

Edge connectors

High quality edge connectors factory mounted and wave soldered to eliminate this nuisance foryou. Completely checked out for shorts or open traces. ALL edge connectors furnished, 12 forthe MCS-112 and 22 for the MCS-122. No additional expense when you expand yoursystem.

The power supply

One of a kind ... using a constant voltage transformer (CVT) with a very

high immunity to input line noise ... greater than 100 db rejection.

Line regulation better than ± 1% from an input of 95 to 140 Volt

AC at full load to 85 to 140 Volt AC at three quarter load.

Designed to meet UL-478 specifications (EDP SPECS).

Individual fusing on all input and output voltage

lines. See specifications below for power

ratings.

.The cooling system

A 115 CFM muffin fan with acommercial grade washable filterwill provide clean airflow over allcircuitry

The wiring

All wiring is color coded and ALL isprecut to length with connecting lugsfactory machine applied.

NOW ... TEI puts it all

together for you. Mainframe

systems ( 12 and 22-slot) ...

Floppy and mini-floppy disc drive

systems (single, double and triple) 16K

RAM ... a 8080A CPU with addressable

"jump to" and autostart capability ... 16

Channel A/D and D/A converter ... 3 serial + 3

parallel multiple I/O ... and other supporting boards

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CRT, keyboard, mini-floppy disc and 12-slot mainframe with a

8080A CPU - all housed in one quality aluminum case. All of

these fine products at prices you will like. Watch for them all.

MCS

SPECIAL SYSTEMS GROUP

MICROCOMPUTER SYSTEM

Contact your local TEI Dealer or if you are not near one of our dealers, write or call CMC Marketing Corp direct for more information.

CMC MARKETING CORP5601 Bintliff Suite 515 • Houston, Texas 77036 • Phone: (713) 783-8880

Circle 19 on inquiry card.

BYTE March 1978 63

Photo 4: The main organchamber with portions ofan organ taken from aSacramento church.

speed and simplicity, and it is worth it.While it now seems obvious that this is auseful way to proceed, it somehow tookfour months to find the solution. This isprobably because we are so reluctant towaste memory. A pipe organ costs from$20,000 to whatever you care to spend(a million dollars is not unusual). Thecomputer costs are lost in the small change.For a small organ, the DMA is not evenneeded, and the input and output loops arevery simple:

1. Point to a memory location.

2. Do an input (or output).

3. Move the contents of the accumulatorto that location.

4. Increment the location.

5. Check for done. If not done, do aninput (or output), etc.

The loop can be done on an 8080A at66 kHz. Thus, an entire 20 rank organ canbe updated in less than 0.02 second. TheDMA would do the same algorithm, butat 1 MHz, and would overlap processing.The 8080 with a 2 MHz clock is just fastenough. An 8085 or Z-80 processor wouldbe more than fast enough. Again, rememberthat for a typical home or small churchorgan, the plain old 8080 would have thenecessary speed and that we are discussinga worst case design.

Even with 10 solved, there still remainsthe problem of deciding which pipes are togo on and which to go off. At first this was

a stumbling block in terms of the time itwould take to do the computations. On eachconsole scan, it seemed, a table of couplerswould have to be made up, as well as atable of stops. A key depression, through thecouplers, results in a number of "virtual"key depressions. Since some virtual keys,being higher or lower on the keyboard thanthe original key, will go off the end of akeyboard, they must be deleted from thevirtual key list. The remaining keys thenhave to be processed through the stop listto determine which pipes are to be played.Since the 10 routines take a total of about0.04 seconds already, the processing itselfmust take no more than 0.013 seconds. Justthe checking for out of range virtual keyswould take more time than we can spare.

The easiest solution to the coupler spill-over problem is to include a few extra placesin the shift register on both ends of eachrank. This allows all the ranks to have thesame shift register length whatever theactual number of pipes. The first advan-tage is that out of range virtual key de-pressions need not be checked for, sincethey fall into unused sections of the shiftregister. As with the wasted memory, thecost of the unused shift registers is small.The second advantage is that the electronicsfor every rank, of whatever kind, can bemass-produced. This makes it less expensiveto build, as well as making the softwareeasier to write (aside from merely beingfaster).

64

BYTE March 1978

Why you should buy a digital

multimeter from theleader in digital multimeters.

If you're shopping for your first multi-meter, or moving up to digital fromanalog, there are a few things youshould know.

First, look at more than price. You'llfind, for instance, that the new Fluke8020A DMM offers features you won'tfind on other DMMs at any price. Andit's only $169*

Second, quality pays. Fluke is recog-nized as the leading maker of multi-meters (among other things) with a30-year heritage of quality, excellenceand value that pays off for you in the8020A.

Third, don't under-buy. You may thinkthat a precision S^-digit digital multi-meter is too much instrument for youright now. But considering our rapidlychanging technology, you're going toneed digital yesterday.

If you're just beginning,go digital.

times better than most analog meters.Also, the 8020A's digital performancemeans things like 26 ranges and sevenfunctions. And the tougher your homeprojects get, the more you need the8020A's full-range versatility and ac-curacy. The 8020A has it; analog metersdon't.

Ifyou'reapro.

You already know Fluke. And youprobably own a benchtop-model multi-meter.

Now consider the 8020A: smaller insize, but just as big in capability. Like2000-count resolution and high-lowpower ohms. Autozero and autopolarity.And the 8020A has 3-way protectionagainst overvoltage, overcurrent andtransients to 6000 V!

Nanosiemens?

Conductance To Resistance Conversion

10

q

a

100

1,000

10,000

q-JL

0.1 1 10 100

Conductance (nS) nanosiemens

Why not analog? Because the 8020Ahas 0.25% dc accuracy, and that's ten

Beginner or pro, you'll find the meteryou now have can't measure nanosie-mens. So what? With the 8020A con-ductance function, you can measurethe equivalent of 10,000 megohms innanosiemens. Like capacitor, circuitboard and insulation leakage. And, youcan check transistor gain with a simple,homemade adapter. Only with the 8020A,a 13-oz. heavyweight that goes whereyou go, with confidence.

$169*

Of course, you can pay more. Or less.In fact, you could pay almost as muchfor equally compact but more simplisticmeters, and get far less versatility. And,the 8020A gives you the 'plus' of customCMOS LSI chip design, and a minimumnumber of parts (47 in all). All partsand service available at more than 100Fluke service centers, worldwide. Guar-anteed, for a full year.

Rugged. Reliable. Inexpensive toown and to operate; a simple 9V batteryassures continuous use for up to 200hours.

Where to buy.

Call (800) 426-0361 toll free. Giveus your chargecard number and we'llship one to you the same day. Or, we'lltell you the location of the closestFluke office or distributor for a per-sonal hands-on feel for the best DMMvalue going.

*U.S. price only

Fluke 8020A DMM forHome Electronics Experts: $169

1808-7101Circle 47 on inquiry card.

IFLUKEI

®

BYTE March 1978

65

Photo 5: A rank of chimespipes.

Except to satisfy traditional organists,there is no reason to have intermanualcouplers on a computer controlled pipeorgan. The original reason for includingintermanual couplers was to minimize thelimitations imposed by the separation ofthe pipes into divisions. The computer, bybeing able to assign any rank to any manual(or to the pedals), eliminates the need forthese couplers. They might well be elimi-nated in my own organ.

Another choice to be made is whether torecalculate all the pipes to be played, or justto modify the previous state on each cycle.It was decided to recalculate from scratcheach time to eliminate the possibility ofcumulative error. It also means that keybounce is automatically taken care of. Inthe slight time between updates, an organ

pipe cannot even begin to sound. A spurioussignal for one cycle is effectively ignored.Continuous pipe-on instructions emittedover a period of approximately 0.1 secondor more are required before the slow mech-anical valves can react. The higher pitchedpipes respond quickly, incidentally, and thelow pipes sometimes take nearly a secondto begin playing. Organists learn to com-pensate by playing low notes somewhatearly. Without introducing a constantacross-the-board delay, it does not seempossible to have the computer compensatefor the effect, but it is a place where someexperimentation might be interesting. Ex-perienced organists, of course, might lookaskance at such an innovation, but theyneedn't be told about all of our ideas.

To summarize: A cycle of the com-puter organ system starts by pulling in thestate of the console. The second part of thecycle (yet to be described) calculates thepipes that should be playing, given the stateof the console. The third portion of thecycle sends the pipe commands along theshift register. This process is repeated atleast once every 1 /30 of a second.

A coupler (of whatever kind) is merelya displacement. It is easily calculated be-cause all keyboards and ranks are the samenominal length. Likewise, engaging a stop isalso a displacement of a distance equal tothe difference between the bottom of themanual's image in memory and the bottomof the rank's image in memory. Thus, thesedisplacements or offsets can be simply addedto yield the offset for a combined coupler-stop setting.

An example, with a simplified organ,will demonstrate how the algorithm op-erates. Say there is one manual with ten keysnumbered one through ten. They are readinto memory locations (all numbers will bein base 10 for this discussion) 1001 through1010. The ranks each have ten pipes, andthere are two of them. The first rank isstored in locations 2001 through 2030.The second rank is stored in locations 3001through 3030. Remember that the area setaside for each rank is larger than the actualspace necessary (here three times as large).There are two stop switches, stored in loca-tions 4001 and 4002. There are twocouplers. They are stored in 4003 and 4004.The first couples up five pipes high, thesecond down three pipes low.

When the low order bit in 4001 is on (orhigh), the program adds 2010 to the keyaddress to get the pipe address. When theother stop is on, 3010 is added. If the firstcoupler is on, an additional 5 is added, andthe second coupler subtracts 3 (or adds a

66

BYTE March 1978

Meet the TSCText Handlers!

Text Editing System

This Editor has caused more talk than anyother TSC program. Most users find it hard tobelieve its power. The TSC Text Editing Systemwill allow extreme ease in any text preparation,whether it be an assembler language programor a legal document.

Included are all the usual edit features pluscommands for block move, block copy, tabs,local and global string changes, and overlays.All editor commands can be used as contentoriented commands. The commands mayalso be used in a character, line, or relativeposition fashion and either in a local or globalsense.

Some other unique features include theability to work forward or backwards through afile, restrictive column zone definitions, a de-finable tab fill character, plus many more.

The TSC Text Editing System comes com-plete with assembler language source listingand a very thorough users manual which in-cludes a "Mini-Tutorial" for those wishing to getstarted immediately.

6800SL68-24 Manual and Source Listing $23.50With Cassette 30.45

With Paper Tape 31.50

8080SL80-10 Manual and Source Listing $28.50With Paper Tape 37.50

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Text Processing System

The TSC Text Processing System is by farthe most powerful text formatter available to themicro user. Over 50 commands are providedfor easy paging, margin setting, and spacing.Right, left, right and left, and center justificationmodes are all handled. The TSC Text Proces-sor is actually a formatting language whichallows the creation of macros including vari-ables. All of these features allow for veryefficient footnote handling, special documentpreparation, and form letters.

Other features supported include pagenumbering (either Arabic or Roman Numerals),complete page size control (line length, pagelength, top, bottom, left and right margins, etc.),tabs, conditional formatting control, exact titleplacing, contiguous space and text control, plusmuch, much more.

The Text Processor in conjunction with theText Editor will give your micro the powers ofthe best text processing system available. Thecomplete assembler language source listingand extensive users manual are included.

6800SL68-29 Manual and Source Listing $32.00With Cassette 38.95

With Paper Tape 40.00

8080SL80-11 Manual and Source Listing $32.00With Paper Tape 41.00

8080 SYSTEMSNOW AVAILABLE!

BYTE March 1978

67

Acknowledgements

Certainly at leasthalf of the Ideas ex-pressed in this paperare due to my friendand colleague, DougWyatt. All of the Ideaswere developed in colla-boration with ' him.Thanks are also due toJim Brennan, who ownsthe incredibly large or-gan so often mentionedin and photographedwith this article, andwhose cooperation aridinspiration have beenessential to the project.

negative 3; it is all the same thing). Theaddition is done only once. Say the first stopand the second coupler were operated;then, given a key on at location 1005, toget the proper location to turn the pipe on,one merely adds (2010-3) or 2007 to thekey location (1005+2007)=3012. This isindeed the correct pipe.

The microcomputer gives the useranother option. When a stop and a couplerare operated, one gets both the note givenby the stop and the extra note given by thecoupler. With a computer it would bepossible to give just the note given by thecoupler acting on that stop. Since each stopcan have a whole panoply of couplersattached to it, the number of buttons wouldsoon become unworkable. For completeflexibility, the organist would have to beprovided with a keyboard and display. Onewould play the organ by setting up manyrequired presets with whatever degree offlexibility required, and then the easily hittabs would not activate stops, but wouldbring in the organist's choice of registrations.

In the example above, choosing bothstops and both couplers would necessitatethe addition of six numbers to each keylocation to obtain the pipe location. In theactual implementation, the program would,for each manual, do the following:

1. Scan the list of stops, and make atable of addends.

2. Scan the couplers, and add them toeach stop, extending the list ofaddends.

3. Add the addends to the locations ofthe manual that contain a 1 (meaninga key depression).

4. Turn on the low order bit in theindicated word in the pipe image.

Intermanual couplings look just like anyother kind of coupling. Say that one manualis stored in 1001 through 1010, and anothermanual at 1201 through 1210. Couplingthe first manual to the second merelymeans adding 200 to the locations of thefirst manual. Just which intermanual coup-lers will be allowed must be carefully speci-fied. If anything is allowed, we may get thefollowing cat chasing its tail effect: Manual1 is coupled to manual 2 at the same pitch.Manual 2 is coupled to manual 1, but onekey higher (a semitone or half step higherin musical terminology). Press C on manual1. C gets played on manual 2. This forcesC# on manual 1. But this makes C# playon manual 2. Every key is thus beingplayed. As implied above, though, inter-manual couplings are necessary only onorgans where the pipes are separated into

divisions. In the computer controlled pipeorgan they can and should be eliminated.Everything they can do, and more, can bedone by freely assigning ranks to keyboardsas desired. I am not sure that all organistswill be convinced by this.

Future Fugues

The organ console of the future, as itappears in the light of the computermediated organ, looks like this: The manualsand pedals are built to the usual AGO(American Guild of Organists) standards.These standards are excellent, and permitan organist to travel from one instrumentto another with a minimum of relearning.Instead of the usual arrangement of stops,there are as many rows of stops as there arekeyboards. When a stop is to be assignedto a given keyboard, the button in the rowrepresenting that keyboard, and in thecolumn representing that stop, is pressed.Any particular registration may be cap-tured by pressing the "capture" buttonand, while holding it, operating the chosenpreset button. The stop buttons should,as on conventional organs, move (or lightup) to show what choices have been made.This is not far from conventional practice.

The possibilities in a console screen,with alphanumeric readout, are endless,and would require another article to explore.Similarly, the gimmicks, from very usefulones that record (on a disk or cassette)the performance in terms of keystrokes,to silly ones (for example, connecting thedoorbell to the computer, so that the organplays "Jesu, Joy of Man's Desiring" whena visitor presses the door button) wouldagain take up too much space here.

Summary

The reasons for using a computer in apipe organ are these:

1. Simplification of the wiring of theorgan.

2. Greater reliability than conventionalswitching.

3. Lowered expense in medium andlarge instruments.

4. Much greater control of the instru-ment by the performer.

5. New freedoms in choosing regis-trations.

Nothing, it would seem, is lost by going toa microcomputer, and one could keep ad-vantages 1, 2 and 3 above while keepingthe appearance and operation of the pipeorgan unchanged, in case any organistschoose not to use advantages 4 and 5."

68

BYTE March 1978

LOADED WITH EXTRASAT NO EXTRA COST

Microprocessor controller

Serial RS232C interface

Parallel TTL level interface

Full upper and lower case

ASCII character set (96

characters)

Full 8V2 inch wide paper

Line length of 80 columns at

10 characters per inch

Impact printing

7 x 7 dot matrix

Ordinary paper—roll, fanfold,

or sheet

Serial baud rate to 1200 bits

persecond

Multiple line buffer of 256

characters

Built-in self test mode

Instantaneous print rate to

100 characters per second

Sustained throughput to 50

characters per second

Multiple copies without

adjustment

Reinking ribbon mechanism

Expected ribbon life of 10

million characters

Front panel operator controls

Attractive table top console

Check theimpressivefeatures onIntegral'snewlP-125Impact Printer

onlylp/iJlJ

Complete, ready-to-operate..the first impact printer to offerbig printer performance at amini-printer cost.

Write for complete informationor call (617) 926-1011

IntegralData Systems

V- -f- INC

5 BRIDGE STREETWATERTOW.N, MASS. 02172

. AND FOR VERY LITTLE MORE

Line lengths to 132 columns

Instantaneous print rate to

165 characters per second

Sustained throughput to 80

characters per second

Print densities of 8.3,10,12

and 16.5 characters per inch

Options program selectable

by control codes

Full CRT screen size multiline

buffer (2048 characters)

Special set of graphic symbols

Graphics mode dot plotting

Form feed control

Eight switch selectable form

sizes

Automatic page boundary

skip

Remote printer selection/

deselection

Automatic line feed on

carriage return

IP-225

"The Tractor Impact"

onlyp94y

the pin feed version of the IP-125 with

tractor drive forms control plus all thestandard features of the IP-125.

Circle 56 on inquiry card.

BYTE March 1978

69

wire wrappingcenter

Wire-wrapping, stripping, unwrapping tool forHOBBY WRAP AWG 30 on025 (0,63mm) Square Post.TOOL

Regular Wrap

WSU-30

$6.95

Modified Wrap

WSU-30M

$7.9 5

NEW

WIRE-WRAPPING TOOL

For .025" (0,63mm) sq. post"MODIFIED"wrap, positiveindexing, anti-overwrappingdevice.

for quality electronic parts and tools.

Battery

wire

wrapping

tool

COMPLETE

WITH BITANDSI.KKVI

For AWG 30

BW-630

$34.95*

For AWG 25-28

BW-2628

$39.95*

Bit for AWG 30

BT-30

$3.95

Bit for AWG 26-28

BT-2628

$7.95

^USE"C"S1ZE NI-CAD BATTERIES(NOT INCLUDEO)

WIRE-WRAPPING KITS

Contains: Hobby Wrap Tool WSU-30,(50 ft.) Roll of wirePrestripped wire 1" to 4"lengths (50 wires per package)stripped 1" both ends.

Wire Wrapping Kit. IBIuel

WK-2B

$12 95

Wire Wrapping Kit, lYeriowl

WK-2-Y

$1295

Wire Wrapping KiUWhitel

WK2W

$12.95

Wire Wrapping Kit IRed)

WK-2-R

$1295

ROLLS OF WIRE

Wire for wire-wrapping AWG-30(0.25mm) KYNAR' wire, 50 ft. roll,silver plated, solid conductor,easy stripping.

30 AWG Blue Wire. 5011 Roll

R 308-0050

$1.98

30-AWG Yellow Wire 50ft Roll

R30Y-005O

$198

30 AWG White Wire 50ft Roll

R30W-0050

$198

30-AWG Red Wire. 50ft Roll

R-30R0050

$198

WIRE-WRAPPING KIT

Contains: Hobby Wrap Tool WSU-30,Roll of wire R-30B-0050, (2) 14DIP'S, (2) 16 DIP's and Hobby BoardH-PCB-1.

Wire-Wrapping Kit [wK-3B (Blue)| $16.951

WIRE DISPENSER

■ With 50 ft. Roll of AWG 30KYNAR' wire-wrapping wire.

■ Cuts the wire to length.

■ Strips 1" of insulation.

■ Refillable (For refills, see above)

Blue Wire

WD-30-B

$335

Yellow Wire

WD-30-Y

$3.95

White Wire

WD-30-W

S3.95

Red Wire

WD-30 R

$3.95

WIRE-WRAPPING KIT

Contains: Hobby Wrap Tool WSU-30 M,Wire Dispenser WD-30-B, (2) 14 DIP's,(2) 16 DIP'S, Hobby Board H-PCB-1,DIP/IC Insertion Tool INS-1416 andDIP/IC Extractor Tool EX-1

PRE CUT

PRE STRIPPED WIRE

Wire for wire-wrapping,AWG-30(0.25mm) KYNAR"wire, 50 wires perpackage stripped1" both ends.

3D-AWG blue Wire. 1" Long

30B-50010

$99

30-AWG Yellow Wire. 1" Long

30 Y-50 010

$99

30 AWG White Wire. 1" Lcr.p

30W-50 010

J 99

30-AWG Red Wue 1" Lone

30-R-50-010

$99

30-AWG Blue Wire. 2" Long

30B50020

$107

30AWG Yellow Wire. 2" Long

30 Y 50 020

$107

30 AWG While Wue. 2" LonR

30 W 50-020

$107

30 AWG Red Wue 2" LonR

30 R 50 020

$107

30 AWG Blue Wire, 3" Long

30B50030

$1.16

30-AWG Yellow Wire. 3" LonR

30-Y-5O-O30

$1 16

30 AWG While Wue. T Lone

30 W 50030

$1 16

30 AWG Red Wire. 3" LonR

30 If 50030

$1.16

30 AWG Blue Wire 4" 1 ong

30 B 50-04Q

$123

30 AWG Yellow Wire. 4" LonR

30 -Y 50 040

$1.23

30 AWG While Wire. 4" LonR

30 W 50-040

$123

30 AWG Red Wire. 4" Long

30 R 50 040

$123

30 AWG Blue Wue. 5" Long

30 B 50 050

$1 30

30 AWG Yellow Wue. 5" Long

30 Y-50 050

$1 30

30 AWG White Wue. 5'" Long

30 W 50 050

$130

30 AWG Red Wue. 5" Long

30 R 50 050

$1 30

30 AWG Blue Wire. 6'" Long

30 B 50 060

$1 38

30 AWG Yellow Wire. 6" Long

30 Y-50060

$1 38

30 AWG White Wire.6" Long

30 W 50-060

$138

30 AWG Red Wue. 6" Long

30R-50 060

$1 38

KYNAR PENNWAlT

70 BYTE March 1978

14-16 Pin Dip IC Inserter | INS-1416 | $3.49]

DIP/IC EXTRACTOR TOOL

Extractor Tool

EX-1

$1.49

P C BOARD Tne 4 x 4.5 x 1/16 inch board is made of glass coaled EPOXY Laminateand features solder coated 1 oz. copper pads. The board has provisionfor a 22/44 two sided edge connector, with contacts on standard .156spacing. Edge contacts are non-dedicated for maximum flexibility.

The board contains a matrix of .040 in. diameter holes on .100 inchcenters. The component side contains 76 two-hole pads that can accom-modate any DIP size from 6-40 pins, as well as discrete components.Typical density is 18 of 14-Pin or 16-Pin DIP'S. Components may besoldered directly to the board or intermediate sockets may be used forsoldering or wire-wrapping.

Two independent bus systems are provided for voltage and ground onboth sides of the board. In addition, the component side contains 14individual busses running the full length of the board for complete wir-ing flexibility. These busses enable access from edge contacts to distantcomponents. These busses can also serve to augment the voltage orground busses, and may be cut to length for particular applications.

Hobby Board

H-PCB-1 $4.99

\« «$L^r.sk »\

r^^^s^gggj^

PC CARD GUIDES

Card Guides | TR-1 | $1.891

QUANTITY - ONE PAIR (2 pes.)

PC CARD GUIDES & BRACKETS

Ouides & Brackets | TRS-2 | $3.79 [QUANTITY - ONE SET (4 pes.)

PC EDGE CONNECTOR

44 Pin, dual read out, .156" (3,96mm) Contact Spacing, .025" (0,63mm) square wire-wrapping pins.

\ P.C, Edge Connector | CON-1 | $3.49]

P.C.B. TERMINAL STRIPS

e TS strips provide positive screw activated clamp; action, accommodate wire sizes 14-30 AWG (1. 8-0.

— . n?__ ^nF,lr.. nlnl..^ ^r........ f\A O „-."!. /lmm'

solder plated copper,.042 inch (lr

4-Pole

TS- 4

$1.39

8-Pole

TS- 8

$1.89

12-Pole

TS-12

$2.59

:1k

DIP SOCKET

Dual-in-line package, 3 level wire-wrapping, phosphor bronze contact,gold plated pins .025 (0,63mm) sq.,.100 (2,54mm) center spacing.

14 Pin Dip Socket

14 Dip

$0.79

16 Pin Dip Socket

16 Dip

$0.89

RIBBON CABLE ASSEMBLYSINGLE ENDED

With 14 Pin Dip Plug24" Long (609mm)

SE14-24 $3.55

With 16 Pin Dip Plug24" Long (609mm)

SE16-24

$3.75

DIP PLUG WITH COVER

FOR USE WITH RIBBON CABLE

14 Pin Plug& Cover

16 Pin Plug & Cover

14-PLG $1.45

16-PLG $1.59

QUANTITY: 2 PLUGS. 2 COVERS

RIBBON CABLE ASSEMBLYDOUBLE ENDED

With 14 Pin Dip Plug-2" Long

DE 14-2

$3.75

With 14 Pin Dip Plug -4" Long

DE 14-4

$3.85

With 14 Pin Dip Plug-8" Long

DE 14-8

$3.95

With 16 Pin Dip Plug-2" Long

DE 16-2

$4.15

With 16 Pin Dip Plug -4" Long

DE 16-4

$4.25

With 16 Pin Dip Plug -8" Long

DE 16-8

$4.35

ateeafjj

WWT-4

TERMINALS

■ .025 (0,63mm) Square Post

■ 3 Level Wire-Wrapping

■ Gold Plated

Slotted Terminal

WWT-1

$2.98

Single SidedTerminal

WWT-2

$2.98

IC Socket Terminal

WWT-3

$3.98

Double SidedTerminal

WWT-4

$1.98

25 PER PACKAGE

TERMINAL INSERTING TOOL

For inserting WWT-1, WWT-2, WWT-3,and WWT-4 Terminals into .040(1,01mm) Dia. Holes.

INS-l $2.49

WIRE CUT AND STRIP TOOL

Easy to operale .. . place wires (up to 4) in stripping slot withends extending beyond cutter blades ... press tool and pull. . . wire is cut and stripped to proper "wire-wrapping" length.The hardened steel cutting blades and sturdy construction ofthe tool insure long life.

Strip length easily adjustable (or your applications.

DESCRIPTION

MODELNUMBER

ADJUSTABLE

"SHINER" LENGTH

OF STRIPPED WIRE

INCHES TO INCHES

Price

24 ga. Wire Cut and Strip Tool

ST-100-24

IV IX."

$ 8.75

26 ga. Wire Cut and Strip Tool

ST-100-26

IS." 1"(."

$ 8.75

26 ga. Wire Cut and Strip Tool

ST-100-26-875

%" l'/a"

$ 8.75

28 ga. Wire Cut and Strip Tool

ST-100-28

%" l'/a"

$11.50

30 ga. Wire Cut and Strip Tool

ST-100-30

%" l"/a"

$11.50

THE ABOVE LIST OF CUT AND SKIP TOOLS ARE NOT APPLICABLE F0H

TEfl ON INSULATION

MINIMUM ORDER £25 00 SHIPPING CHARGE St 00 N Y. CITY AND STATE RESIDENTS ADD TAX

OK MACHINE & TOOL CORPORATION

3455 Conner St . Bronx. NY 10475B(212) 994-6600BTelex 125091

Circle 84 on inquiry card.

BYTE March 1978

Buy a dumb terminal

the smart way

and save 1/3.

Introducing

Dynabyte's

new Naked

Terminal:

Buying a dumb terminal used to get

pretty expensive. About $ 1,000. But

that was the old, dumb way. Now there

is a new, smart way to add a dumb

terminal to your system. Our Naked

Terminal is $350. Add a keyboard and

video monitor at a total cost of about

$650. You save around $350!

The Naked Terminal does all that a dumbterminal does. Some things it does better.

It displays 80 characters per line by 24 lines. And

it displays it on any screen size: 9, 12, 15 or

whatever size you prefer. The $ 1,000 one

doesn't give you a choice. Both upper and lower

case characters are displayed in a 5 x 7 font.

Although you spend less money you get more

features: half duplex, full duplex, and a block mode

that allows editing before transmission.

You-know-who doesn't have a block mode.

72

The Naked Terminal has addressable cursor. And its

display offers you lots of switch-selectable flexibility:

black-on-white or white-on-black, blinking or

non-blinking underline cursor, and

variable baud rates.

No software support is required. The Naked Terminal

can be configured by dip switch to drop into an

existing system, replacing the serial I/O card and

stand-alone terminal without making any

changes to software.

The Naked Terminal is a complete dumb terminal on an S-100 board. It contains a microprocessor

with its own memory, its own software drivers, and its own internal bus. We built it that way so it won't

take up any of the 64k memory address space of the S-100 bus. Keyboard and video monitor

cables are available at additional cost.

Like all Dynabyte products, the Naked Terminal is completely assembled, socketed, tested andburned in. Dynabyte's guarantee is for a full year - the longest in the industry.

Now isn't the Naked Terminal a smart buy? Learn more about saving 1/3 on a dumb terminal. Askyour local computer retailer. Or write today to Dynabyte, Inc., 4020 Fabian, Palo Alto, CA 94303.

Telephone (415)494-7817. ■^■■■^■^■^■■hih

BYTE March 1978

Now Dynabyte builds three Great Memories

* New! 16k and 32k fully static RAM's. With either 250 ns. or 450 ns. .*' • typical access time. Assembled. Tested. Burned in. Guaranteed.

Like our 16k dynamic RAM. Built as solid as the 4,400 year-old pyramids.

Ancient Egyptians didn't stopwith just one pyramid. The GreatPyramid stands on the PlainofGizeh with two other monumentserected for kings and queens.

Dynabyte didn't stop with one16k dynamic RAM, either. Now ,you can get 16k and 32k fullystatic RAM's that are built with thesame unmatched engineeringability and manufacturing skillthat went into Egypt's wonders ofthe ancient world.

When we say built, we meancompletely built. Assembled,tested and burned in. We don'tleave anything undone. That way,you can buy any Dynabytememory and know that it is backedby a factory guarantee for one fullyear. Kits and semi-kits can'tsay that.

Our 16k static and our 32kstatic are available with either 250ns. or 450 ns. access time. Our250 ns. module is completelycompatible with the 4MHz Z-80Aprocessors. The 450 ns. modulesare compatible with the 8080 andthe faster 3MHz 8085 processors.

The Great 16k StaticMemory. 250 ns., $555.450ns., $525.

• 4k block addressing along 4kboundaries

Circle 41 on inquiry card.

• Bank Select

•' Write Protect with alarm foreach 4k block

• Full Schmitt trigger buffering

• No DMA restrictions

• Completes-100bus com-patibility, including the AlphaMicro and Z-2.

The Great 32K StaticMemory. 250 ns., $995.450ns., $925.

• 4k boundary addressing

• Full Schmitt trigger buffering

• No DMA restrictions

Why Dynabyte doesn'tbuild memory kits

Assembling a kit can be fun;almost anyone can do it.

But how about testing it?Do you have the test programsand equipment? Do you knowwhich memory test programuncovers pattern sensitivity?Or which finds shorted databits but won't find addressdecoder faults?

We do. It's our business. Wehave the 200 MHz oscillo-scopes, the logic analyzers, theburn-in chambers, and the testprograms. We find the bugs,even the subtle ones.

Which lets you concentrateon computing.

* • Conservative thermal design» Completes-100compati-bility, including the AlphaMicro and Z-2.The Great 16k DynamicMemory. $399.

• Highly cost effective

• No wait states

• Transparent refresh

• 16k addressing boundaries

• Widest S-100 mainframe anddisk system compatibility

All of Dynabyte's memoriesmeet rigid industrial grade stand-ards. Design, components, con-struction, testing and perfor-mance. But if a module ever needsrepair, we provide factory servicewith 24 hour turnaround for bothwarranty and non-warranty work.

Ask for the Great Memories byDynabyte at your local computerstore. You can also pick up com-plete product information whileyou're there.

But if you haven't got a localcomputer store, write Dynabyte,Inc., 4020 Fabian, Palo Alto, CA94303. Or telephone (415)494-7817.

Builders of Great Memories

BYTE March 1978 73

Ernest W Kent, Associate ProfessorDept of Psychology

The University of Illinois at Chicago CircleChicago IL 60680

The Brains of Men and Machines

Part 3: How the Brain Analyzes Input

Note: A number of theterms which are used inthis article were definedand discussed in the firstarticle of this series whichappeared in Janurary 1978BYTE, page 11.

Perhaps the most remarkable feat per-formed by organic brains is the resolutionof the flood of data flowing from the sen-sory receptors into conceptually meaningfulelements. It is also one of the most difficulttasks faced by the designer of robot systems.Consider the nature of the informationwhich the brain receives about the visualworld. Patterns of light, of varying wave-length and intensity, are imaged on theretina of the eye by the lens. This illumina-tion results in a barrage of neural impulsesflowing through millions of fibers in theoptic nerve and activating neurons in aportion of the cerebral cortex called theprimary visual cortex. Obviously, ourvisual experience is nothing like this barrageof impulses in axons. We "see" objects,colors, groupings of objects, all interpretedin meaningful terms. Our experience of thevisual world is thus a far different matterfrom the visual stimulus which initiates theexperience. It is not necessary that a robothave "experience" as we do, but it is neces-sary for one to resolve the sensory informa-tion into behaviorally relevant elementsas we do.

To understand the nature of the opera-tions that are being performed, we mustcarefully discriminate between the terms"stimulus" and "sensation." "Stimulus"

refers to the actual physical event thatactivates a receptor. In the case of vision,this would be a ray of light falling on theretina. Since the intensity and wavelengthof this light are determined by propertiesof the physical object which reflects it, andsince there is a fixed relation between thetwo, we often refer to the reflecting objectas the stimulus, with the understanding thatits action as a stimulus depends on theproperties of the light it reflects. "Sensation"on the other hand refers to a property of ourmental experience which results from certainkinds of activation of our receptors. Thereis a close relation between the sensations wehave and the stimuli which produce them.Our senses would be useless if it were not so.However, this close relation often leads usto confuse the two, and this is a great error,because they belong to entirely differentworlds. A stimulus is a physical object; asensation is a mental event.

To clarify the distinction, consider thesensation of the color red. We all know whatwe mean when we say an object "is red," orthat we "see a red object." A moment'sreflection though will demonstrate that,strictly speaking, there can be no such thingas a red object. The object can only possessor not possess the properties necessary toreflect light of a particular wavelength. If an

74

BYTE March 1978

object reflected light of a wavelength whichgave rise to the sensation "red," and we wereto somehow change the wavelength betweenthe object and the eye, the object wouldappear to be of some other color. Can wethen say that "redness" is a property of thelight? No, because the only relevant physicalproperty of the light is its wavelength, andwavelength is not a color. Color is a propertyof your sensation.

Sounds have wavelengths too, and therethe sensation is interpreted as pitch. Wave-length is only a piece of information whichthe brain can interpret as it will. In yourcomputer, you could make an analogy withASCII code. We use particular bit patterns torepresent letters and numbers, but the samebit patterns could just as easily representsomething else. There is nothing thatinherently requires the binary pattern01000001 to be interpreted as A. Similarly,"redness" as an interpretation of a particularwavelength is simply a convention that thebrain uses.

The situation becomes clearer if one goesinto the brain a little further. Sensation isnot a result of activating the retina or theoptic nerve. If the optic nerve is cut, lightfalling on the retina produces no sensation,

even though the retinal neurons and theiraxons in the optic nerve are activated. Atthe same time, however, artificially acti-vating the visual cortex to which the nerveused to project will result in visual sen-sations. It follows that sensation is, or is de-pendent upon, the firing of neurons in thevisual cortex. Yet, after striking the retina,light never reaches the visual cortex. All thatdoes reach it is a pattern of neural activityin the axons of the retinal cells. Informationabout the wavelength of the light strikingthe retina is carried in the optic nerve byplace code. That is, the wavelength informa-tion is carried to the visual cortex in termsof which lines are active. There is certainlynothing that seems intuitively "red" aboutwhich of a set of axons are carrying impulses.Yet, the sensation of "redness" clearlyoccurs at or beyond the cortex, after thatencoding process. If we could somehowchange which set of axons were active be-tween the retina and the cortex, the sensa-tion produced by the light would change.

Sensation = Information Processing

Now if we accept the notion that sensa-tions are mental events that are produced, or

r

WHAT WOULD YOURPERSONAL COMPUTER SAY

IF IT COULD TALK?

GET SPEECH POWER

WITH THE

COMPUTALKER

SPEECH SYNTHESIZER

S-100 BUS

ASSEMBLED CIRCUIT BOARDCOMPLETE WITH SOFTWAREFOR PHONETIC INPUT

CALIF RESIDENTS ADD 6% SALES TAX

430.00

WRITE FOR INFORMATIVE LITERATURE

COMPUTALKER CONSULTANTSP.O. BOX 1951, DEPT. B, SANTA MONICA, CA 90406

ARIZONAByte Shop of AZTempe, (602) 894-1129

CALIFORNIA

A-Vidd Electronics

Long Beach, (213) 598-0444

Byte Shop ot Lawndale

Lawndale. (213) 371-2421

Byte Shop of San Diego

San Diego, (714) 563-8008

Byte Shop of Santa Clara

Santa Clara, (408) 249-4221

Computer Center

Costa Mesa, (714) 646-0221

Computerland of San Diego

San Diego, (714) 560-9912

The Computer Mart

Orange, (714) 633-1222

Computer Playground

Westminster, (714) 898-8330

The Computer Store

Santa Monica. (213) 451-0713

Computer Store of SF

San Francisco, (415) 431-0640

Mission Control

Santa Monica, (213)829-5137

Recreational Computer Centers

Sunnyvale, (408) 735-7480

Westminster Byte Shop

Westminster, (714) 894-9131

Ximedia

San Francisco, (415) 566-7472

GEORGIA

Computer Systemcenter

Atlanta, (404) 231-1691

Dstamart, Inc.

Atlanta

Home Supply Company

Rock HillILLINOIS

The Data Domain of Schaumburg

Schaumburg, (312) 397-8700

INDIANAThe Data DomainBloomington, (812) 334-3607

KANSASMicro-Corn, Inc.Kansas City, (816) 333-8383

MICHIGANComputer Mart of Royal OakRoyal Oak, (313) 576-0900Computer Store of Ann ArborAnn Arbor, (313) 995-7616

NEW JERSEYHoboken Computer WorksHoboken, (201) 420-1644Computer Mart of NJIselin. (201) 283-0600

NEW YORKThe Computer TreeEndwell. (607) 748-1223The Computer StoreNew York, (212) 221-1404

NORTH CAROLINAByte Shop of RaleighRaleigh, (919) 833-0210Computer Stores of Carolina, Inc.Charlotte, (707) 334-0240

OHIO

Digital Design

Cincinnati, (513) 561-6733

OREGONByte ShopPortland, (503) 223-3496

PENNSYLVANIAMarketline SystemsHuntington Valley

SOUTH CAROLINAByte ShopColumbia, (803) 771-7824

TEXASThe Computer StoreHouston, (713) 522-7845

WASHINGTON DC,VIRGINIARoberts Information Services, Inc.

Fairfax, (703) 560-7888

AUSTRALIA:

Carnegie, Sontron Instruments596-7867

AUSTRIA

Vienna, Margreiter GMBH(0222) 96 15 65

CANADA

Toronto. The Computer Place(416) 598-0262TELEX 06-22634

ENGLANDLondon, Compelec Electronics310 Kilburn Highroad

FRANCEParis, Computer BoutiqueTel. 758.62.60Paris, Hugues Gosset15 Rue de Franqueville

GERMANY

Muenster, BASIS MicrocomputerTel. 0 25 01/48 00Munich, Datameg(089) 46 50 66

ISRAELHashsron, Bernard RoizenTel. 48-1269

JAPANTokyo, Byte Shop Sogoh

Chiyoda-ku, Tokyo 10103 (255) 1984Tokyo, Kazuhlko Nlshl(03) 373-3935

Circle 22 on inquiry card.

BYTE March 1978

75

at least determined, by the brain decodingstimulus produced activations of receptorlines according to specified conventions, itbecomes clear that the process of sensationis basically one of information processing.The nature of the conscious "experience"of the processed data is a topic we shall takeup later. For now, our objective will be toexamine the kinds of transformations thebrain imposes on its input data and to askwhy this particular transformation and notsome other is useful to the organism in deal-ing with the environment. The utility ofsuch a pursuit lies in the fact that the mostlikely system for detailed examination ofdistant objects in an artificial robotic systemwill use an image forming system acting on agrid of sensitive transducers. The problemsof information processing in such a systemwill be exactly those that the brain hassolved.

There are about a million light receptiveelements in the retina, and the brain pro-duces a complete analysis of their patternsof illumination about ten times per second.If this were done in a straightforwardmanner, say by examining all the possiblepermutations of a million bits of informa-tion and decoding it against a table ofknown codes, a tenth of a second's worth ofvision would be too big a job even for thebrain to handle in a reasonable time. In fact,it goes to some extremes to cut corners inthis process, and some of its tricks are ofquite general utility. The first step in theprocess is to make a number of decisionsabout what not to look at.

If an area of uniform illumination isbounded by an area of some other degreeof illumination, the information from thecenter of the area is superfluous. That is,if one had a system that could detect onlyboundaries between different illuminationlevels, the center of a uniform boundedarea would not produce a signal. Yet,information about its illumination couldbe accurately reconstructed by simplyextrapolating the illumination level on theinside edge of the boundary clear across tothe next boundary. If the level at the insideedge of the boundary did not hold clearacross the area, that would mean that therehad to be a change, and hence a boundary,somewhere in the middle, and that boundarywould be detected. Any change in illumina-tion constitutes a boundary between alighter and a darker region. Thus, if onlyboundaries can be detected, extrapolation oflevels on either edge of a boundary to thenext boundary reconstructs the whole fieldof illumination.

The reduction in the number of points tobe considered which is achieved by consider-ing only boundaries is quite large. Think ofa square patch of retina 100 receptor ce\\son an edge, illuminated at level A on theright half, and level B on the left. If we hadto examine every element's illumination toarrive at a picture of this pattern, we wouldhave to examine 10,000 elements. If we nowexamine only the ones near the boundarybetween area A and area B, and extrapolatethe rest, we have to examine only about 100elements. In general, the savings go upapproximately as the square of the boundaryof a uniform area.

We will return in a moment to the matterof how the brain locates spatial boundaries,but first mention should be made of thenext shortcut, because their underlyingmechanisms are related. Basically, thissecond trick is to look only at things thatchange. Aside from the fact that changingpatterns of illumination usually imply mov-ing objects, and that these are usuallyimportant items in the sensory world, specialattention to change also has advantages interms of processing time. The situation isreally very similar to the preceding one,except that here we must think of change asrepresenting a temporal boundary betweenillumination levels. If we only attend to anelement when its illumination changes, andif we always know when it does, we cansafely ignore it in the meantime. This isbecause the illumination during the interven-ing period of no change must be at whateverlevel the preceding change brought it to.Thus, it is only necessary to extrapolate thevalue immediately following a change untilthe next change is detected.

The eye is sensitive to two dimensions oflight, intensity and wavelength, which weperceive as brightness and color. We havediscussed the two boundary situations,spatial and temporal, only in terms of bright-ness so far, but the same arguments apply toboundaries of color. Two areas of equalbrightness but different color also must bediscriminated. The same mechanismsactually are applicable to both, since thebrain handles color by providing some re-ceptor elements with differential sensitivityto different wavelengths. For these elements,a change in wavelength effectively is achange in illumination. It will either be froma wavelength to which the element is sensi-tive to one to which it is not, or vice versa.The brain handles the color informationsimply by recognizing the output of theseelements as encoding the wavelength infor-mation, and interprets it as color. The color

76

BYTE March 1978

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BYTE March 1978

77

boundary problem therefore reduces to theintensity boundary problem.

Now let us examine the mechanisms ofboundary detection. The temporal bound-aries, that is, changes in illumination withtime, are responded to selectively by aprocess that is similar in its results to ACcoupling the receptor elements. In fact,AC coupling of analog to digital converterswith an appropriate time constant would bea good way to model the process in a robot.In the brain, it is simply a property of thereceptor neurons themselves, and the detailsneed not concern us. The interesting thingis that the brain uses this same AC coupledcharacteristic of the neural elements todetect both spatial and temporal boundaries.A selective sensitivity to change, or temporalboundaries, is inherent in the AC coupling,but a sensitivity to spatial boundariesrequires some additional mechanism.

We are all aware of course that the eyemoves. We observe it all the time when ourgaze turns from one point of fixation toanother, or when it follows a moving target.In addition to these motions, however, thereis another that is not detectable by ordinarymeans. Even when the eye seems to be atrest, even when you are holding your gazeas intently as possible on a fixed point, thereis still a very fine motion with a frequencyof about 10 Hz. The amplitude of thismotion, which is rather erratic in its direc-tion, is just sufficient to move the retinalimage back and forth over the receptors bya distance equal to a few times the averageseparation between the sensitive elements.Those elements that are near a boundary arethus swept back and forth continuouslyfrom the lighter to darker sides of theboundary at about 10 Hz. This produces inthem a changing signal of the sort to whichthe AC coupled property of the system canrespond. At the same time, their neighborsfurther from the boundary in either thelighter or darker regions to either side arenot moved into a region of different illumi-nation level. Hence, they "see" an unchang-ing input, to which they are insensitive. Thereceptor elements of the eye itself there-fore act as intelligent terminals whichtransmit only information about boundariesand changes to the higher levels, with anenormous savings in amount of input requir-ing attention from more sophisticatedanalyzers.

Now I hear you say, "Yes, but I can seethe insides of uniform areas." True, butremember I said your sensations were anarbitrary decoding of the stimulus informa-tion, and that the information from areasdistant from boundaries was redundant and

could be reconstructed by inference orextrapolation. The experience of "seeing"the inside of the area is simply theexperience of receiving the appropriate codefrom the right set of boundary activatedelements. In the first place, it is relativelyeasy to demonstrate that you cannot seeanything if there is no change. By virtue ofsome clever optics it is possible to stabilizean image on the retina so that it does notmove with respect to the receptor elements,despite the fine motions of the eye. Whenthis is done, the image seems to disappearabout a tenth of a second after it is pre-sented: poof! It is of course still reallythere on the retina, but your AC coupledsystem can't respond. Now, consider a greendisk with a smaller red disk in the center.It is possible to stabilize just one portion ofthis image in the same fashion that westabilized the whole image a moment ago.If we choose to stabilize just the boundarybetween the green outer ring and the redinner disk, it should not be possible for thebrain to detect that boundary. If this isdone, not only do you not see the boundary,you also don't see the inner red disk. Whatdo you see? You see an unbroken greendisk all the way across. In other words, ifno boundary is detected in the middle, thebrain not only doesn't see the red disk, itextrapolates the green all the way acrossfrom one outer boundary to the other.Think about it the next time you rely onthe evidence of your eyes: such evidencemust be interpreted with knowledge of thesystem's characteristics.

The AC coupling is not perfect; there isa "DC leak" around it, but the "changingsignal only" property of the neurons isenhanced at each step in the transmissionprocess, until the cells of the visual cortexare found to have almost no response atall to unchanging uniform illumination ofthe retina. This means that the sensoryexperience of the interiors of uniformregions is simply what is coded for at thecortex by the byte of information on theboundary conditions. It is not a resultof direct translation of retinal illuminationconditions on a point for point basis intoactivation of some set of "experienceneurons." It is important to grasp this idea,because it points up the fundamental simi-larity between the natural brain and theartificial computer. There is no "inner eye"looking out through neural windows. If theencoding process ultimately produces asingle neural line that is activated by, say,the sight of a face, then that line being activeis sufficient for the processing of response tothe face, in man or robot; and at least in us,

78

BYTE March 1978

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79

it is also sufficient for our correlated mentalexperience.

That this is the nature of the encodingprocess for our experiences becomes evenclearer at higher levels of the encodingprocess than those involved in the green andred disk experiment. At some level of theprocess, referred to as "feature extraction,"we arrive at a byte of active lines whichencodes for some complex pattern. Takefor example the repeated patterns of awallpaper covered wall. It seems that even atthis level, the brain continues its policy ofdropping redundant information and carry-ing forward only information on boundaries.If we look at such a wall, we of course seea continuous pattern repeated all the way topattern boundaries such as the ceiling floor,edges of intervening furniture, etc. Nowsuppose we present this same scene to aperson with damage to certain high levels ofthe visual system, having no vision in aparticular small region of the visual field.If his injury is at the right level in thefeature extracting process, he will reportseeing the unbroken wallpaper pattern justas we do, including the region within whichhe is "blind." It can be demonstrated, how-ever, that his experience of the patternin the blind region is due to the fact thatboth he and we are extrapolating thedetected pattern across the intervening spacebetween pattern boundaries. His deficitbecomes apparent when we create aboundary in the pattern within his blindregion. For example, if we inverted a smallpatch of the pattern, it would constitute aboundary in the pattern, and we would notextrapolate across it. If it occurred in hisblind region, however, he would not react tothe pattern boundary and would receive thesame encoded byte of visual informationas before, and claim that he saw an un-broken wallpaper pattern. In an importantsense he is blind, yet he has visual experience.You do the same thing. There is a blind spotin the visual field where the optic nerveleaves the retina. You can make smallobjects disappear by centering them there,but since you can't see boundaries thereeither, your brain normally extrapolatesacross it.

Now we might ask, if the brain is reduc-ing complex features of the visual stimulusto a simple code of one or a few lines, doesthat mean there are things we might nothave feature extractors for, and if so, wouldwe be unable to see them? That is probablyexactly the case. Experiments suggest thatthe visual world of simple creatures likefrogs is quite impoverished. They have somekinds of elementary feature extractors, and

some complex ones for stimuli (eg: bugs)which are important to their behavior, butnowhere near the complex set of featureextractors that a mammal has. In theoryit would be possible to have a unique lineor coded set of lines activated by everypossible combination of activities on theretina, but this would be beyond even thecapacity of the nervous system to generateprocessing elements. Instead, certain deci-sions are made as to what things are impor-tant to see, and decoding for these isprovided. This does not imply that youwould not see anything when looking at anovel stimulus for which you have noappropriate high level extractors. At thefirst level, simple features such as edges,arcs, lines and spots are extracted. Morecomplex features are extracted from com-binations of these. You might be aware onlyof the activity of the low level extractors forlines, edges, etc, and fail to recognize it asan object, or you might fail to discriminateit from objects which were not identical, butdiffered in ways which did not correspondto features you could extract.

As an example, it is possible to fool highlevel extractors by giving them marginaldata. Look at figure 1. About 95 percent ofpeople seeing this picture for the first timeare only able to activate low level extractorsfor patches of bounded light and dark. It isin fact a photograph of the head and upperforequarters of a black and white cow(facing left) against some trees and a fence.Once you know what to look for, you cannudge the "cow extractors" and get anentirely different experience. Indeed, onceyou've seen it, it's difficult to not see it.(Don't panic if you can't; about 5 percentof people never see it.)

Actually, there is probably no "cowextractor" per se, but rather some assem-blage of feature extractors which togetherconstitute a code for "cow." Let's lookhowever at some of the properties whichsuch high level extractors should have. Themost important one is that they should befree of constraints on position, orientation,context, etc. That is, if we had to have aseparate extractor for every position thestimulus might assume in the visual field, wewould need so many elements that theadvantages of the feature extractor approachwould be lost. Next, they should be capableof implementation by learning, so that theavailable processing elements can be bestused to fit the organism's normal visualenvironment. Third, they should not belimited to spatial forms, but should includedetectors for properties such as motion,distance, and other aspects of our visual

80

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experience. These are difficult problems,and we have no good notion of the realnumber or nature of the highest orderextractors in the human visual system.We can examine some of their propertiesby fatiguing the extractors through pro-longed exposure to different types ofstimuli and looking at the effects on ourvisual abilities. In animals, we can followthe process by recording activites of neuronsin the visual system during presentationof stimuli to the eye.

From these latter experiments, we have afairly clear notion of the operation of thelower order extractors, and the processseems easily extensible to higher order

features. To serve as a general example ofthe algorithm, I will describe in detail theprocess by which a feature extractor isformed which can detect a line segment onlyif it is at a particular angle of inclination tothe visual field, but which is location inde-pendent. That is, it does not matter wherethe line is located in the visual field, onlythat it be a line and that it possess a certainangle of inclination. This sort of unit appearsto be one of the typical low level featureextractors of mammalian visual systems.

The basic gating action used is very simi-lar to an AND gate. As we have mentioned,this is one possible mode of action ofneurons, which can be implemented by hav-

Figure I: A white cowwith black ears and nose.The head is turned facingyou, with the side of thehead in shadow. The largewhite area in the lowerright is part of the cow'sleft flank. Before you"see" the cow, all thatappears are white and darkareas. After you "see" thecow, your sensory experi-ence is still the same interms of the stimuli youare receiving, but youranalysis is very different.

BYTE March 1978

81

Figure 2: The generalizedcase of the brain's basicapproach to processing in-put. The two output linesat the top discriminatepatterns of input at thebottom that are verysimilar. In reality, thebrain chooses only someof these possible con-nections to facilitateprocessing.

A B

£lo

ing a number of inputs required to achievefiring threshold. In this case, however, wehave an AND gate with a safety factor. Bythis I mean that firing level is achieved ifsome percentage of the relevant inputs areactive: 100 percent is not required. Thinkof it as an "ALMOST gate." (The brain,unlike our conventional computers, is con-tinually dealing in "best guesses" rather thanprecise solutions, by just this technique.This is why we make mistakes, but it alsoprovides for inductive leaps of enormouspower that are right most of the time.)Connecting a grid of two legged AND gatestogether, as in figure 2, illustrates the basiclogic of the scheme. At the bottom levelwe have a line of receptors. Above theseare several levels of two legged AND gates,culminating in the top level with only twoelements. It is clear that the two top levelelements will discriminate between two

patterns of activation of the bottom rowwhich differ only by one element. Thus,activation of element A encodes the activityof a set of bottom level elements indicatedby bracket A, and element B and bracket Brepresent a different set. If the bottom rowwere retinal receptor elements, A and Bcould be feature extractors for illuminationconditions (A) and (B), which are quitesimilar. It should be apparent that withenough gates and elements, this sort ofgeneral convergence scheme could be em-ployed to extract any feature. This beingimpractical, the brain adds two principleswhich enormously reduce the processingrequired, at the expense of generality. Oncethe set of retinal activation patterns to berecognized has been selected, specificfeature extractors for that pattern are builtfrom the underlying type of logic illustratedin figure 2, but modified by the addition ofprocesses called "selective convergence" and"lateral inhibition." The meaning of theseterms will become clear shortly. At the low-est levels, only a few simple types of featureextractors are implemented and higher levelsbuild progressively on these. To begin with,let us examine the first step in this process.

Within the retina itself, there are severallevels of processing resulting in an outputneuron, a retinal ganglion cell (RGC), whichsends its axon into the optic nerve to enterthe brain. If we record from these RGCneurons, we find that they can be classifiedinto a few basic types depending on thekinds of stimulus to which they maximallyrespond. Figure 3 shows the portions of thevisual field which affect the activity of atypical RGC type, and figure 4 shows theconnections which result in this type of re-sponse. We see that the RGC receives posi-tive synapses from a small group of receptorelements located in a central spot (+ region),and inhibitory synapses from receptorelements in a ring surrounding this spot(-region). Remember that the type ofsynaptic effect is the choice of the receivingneuron, the receptor elements in the "in-hibitory surround" area are free to make

Figure 3: A small area ofthe visual field, showingthe portions which caninfluence the output of asingle retinal ganglion cell(RGC) when illuminated.Some visual neurons actinhibitory (-), others actexcitatory (+).

EXCITATORY CENTER,

LIGHT HERE FACILITATES

RGC FIRING

SMALL AREA OFVISUAL FIELD

INHIBITORY SURROUND,LIGHT HERE SUPPRESSESRGC FIRING

LIGHT HEREHAS NO EFFECT

82

BYTE March 1978

-INTRA-RETINALNEURONS

LIGHT HEREINHIBITS RGC

LIGHT HEREEXCITES RGC

RETINAL GANGLION CELL(RGC)

LIGHT

LIGHT HEREINHIBITS RGC

TO THALAMUSVIA OPTIC NERVE

■RETINAL LIGHTSENSITIVE ELEMENTS

RETINA

facilitatory positive connections with otherRGCs. Now, when the central spot receiveslight, it increases the firing rate of the RGC.When the inhibitory surround is illuminated,it decreases the firing rate of the RGC.(In this and all subsequent descriptions, itis to be taken as understood that we referto the intermittent presentation of thestimulus, either deliberately or throughfine motion of the eye, since the AC coup-ling properties would tend to eliminate theresponse to any maintained stimulus.) Ifthe entire retinal area which affects our RGCis illuminated, the excitatory and inhibitoryeffects tend to cancel. Here as elsewherein the visual system, there is thus littleresponse to diffuse light. Notice that due tothe shape of the inhibitory and excitatoryregions, a line of light just the width of theexcitatory center spot, and crossing the en-tire active area, would fire retinal elementsin both the inhibitory and excitatory re-gions. However, such a stimulus would firethe entire excitatory central region, butwould only fire a small percentage of the

inhibitory elements since it only crosses theinhibitory ring in two spots (see figure 5).The response to a line stimulus crossing thecentral spot would therefore be stronglypositive, although less so than to a stimuluswhich did not touch the inhibitory region.

There are several other basic types ofRGC organization with regard to the sizesand shapes of the retinal areas whose illumi-nation affects them. For example, anothercommon type has the inverse of the type ofreceptive field just considered, that is, aninhibitory center area surrounded by an ex-citatory ring. We shall not pursue these indetail, but pass on further into the brainwith the development of our abstractedinclined line detector. The next way station,the target of the optic nerve, is a nucleusof the thalamus, called the "lateral genic-ulate nucleus." The axons of the RGCsmake synaptic contact with the cells of thisnucleus just as the retinal elements madecontact with the RGCs. If we record fromthese cells while testing for retinal areasthat excite or inhibit them, we find that

Figure 4: The connectionsbetween the retinal ele-ments and the retinalganglion cell (RGC) whichaccount for the patternof sensitivity shown infigure 3. In this view, thepattern of figure 3 wouldbe edge-on as projected onthe retina.

Continued on page 94

AREA WITHIN WHICH

LIGHT INHIBITS RGC

(-)

AREA WITHIN WHICH

LIGHT EXCITES RGC

(+)

CELL OUTSIDERECEPTIVE FIELDOF RGC (NO EFFECT)

BOUNDARY OFBAR OF LIGHTCROSSING RETINALAREA

AREA OF RETINACORRESPONDINGTO AREA OFVISUAL FIELDN FIGURE THREE

Figure 5: An area of theretina corresponding tothe area of the visual fieldin figure 3, showing theretinal elements of figure4 which would be acti-vated by a stimulus con-sisting of a long line oflight.

BYTE March 1978

83

Cispcia'sCircuit

Program Your Next EROM in BASIC

Steve CiarciaPOB 582Glastonbury CT 06033

"Steve, you just gotta help me!" was mynot so usual frantic midafternoon introduc-tion to Jerry. He burst into my office witha manner reminiscent of a storm trooper.The vacuum he created as he rushed towardme around the obstacles in his path causeddisturbed paper work to flutter slowly tothe floor in his wake. He stopped abruptlyat my desk and held the contents of hishand under my nose, hoping to exactan immediate response from me. Beingabruptly summoned and having objectsstuffed in my face is not generally howI like to be approached.

"I hope I'm not disturbing you, Steve,but I need some help." He extended hishand again but knew enough not to stickit in my face. "I accidently blew one of theEROM chips that contains the data ac-quisition software you gave me. We have acomputer club meeting tomorrow nightand I'm supposed to demonstrate my com-puter. I'm just going to look dumb to allthose guys if I don't have a good demon-stration. . ."

I could understand his plight. If Jerrywere to sit down and discuss his problemwith his children, I'm sure his 9 year oldson would describe it as a classic case of peerpressure. Designing control systems forfactories on paper is different from a direct

demonstration of one's capabilities in frontof a knowledgeable group of fellow com-puterists. Jerry was terrified that he wouldbe a flop.

"Hold it Jerry. . . what's the problem?You have a computer. . . I thought youbought an EROM programmer?" I asked,still trying to ascertain the true depth ofhis difficulty. "You have a listing of theEROM contents."

"I've been meaning to get a programmerone of these days, but it costs a fortune.I wouldn't use it enough to justify the ex-pense. I called Bob and he let me look at theassembly listing of an EROM programmer.I brought it along so we could cut anotheron your system. I've never been very goodat assembly language programming. Thelisting of his programmer looks quite in-volved. I'm sure I wouldn't be able to in-corporate it into my operating system bytomorrow night. You just gotta help me,Steve . . . please?"

His pleading was a bit sickening but Icould understand what he was going through."Jerry, why don't you write your ownquick programmer?" I asked. "What do youthink it entails?" The reason for this line ofquestioning wasn't to antagonize or delayhim, but rather to get a handle on what maybe a problem for more people than Jerry.

84

BYTE March 1978

"What do you mean? How to do it?You write an assembly language programthat gets the address and data to the EROMand you hold it there until it's burned in,and step to the next address. But it's allthose program loops to keep track of theaddress, data and timing. I really boughtthis computer to use on BASIC, remember?"

"You've done some extensive BASICprogramming, haven't you? You have acomputer with plenty of parallel input andoutput ports, don't you? Write the EROMprogrammer in the language you understandbest. True, it can be written in assemblylanguage, but it can just as well be writtenin BASIC."

"Huh?" he grunted, still not quite be-lieving me. "What do you mean?"

I felt I had his interest now. I was tellinghim that solving his dilemma need notentail using any more than the canned soft-ware supplied with his system, and that hedidn't have to get involved with the "blackmagic" of assembly language.

"You already said that programming anEROM entailed getting the address and datato the EROM and stepping the addresssequentially. Right?" I said.

"Yes, but BASIC?" he responded.

"Sure, why not BASIC?" I said. "Byusing INP and OUT commands, addressand data can be set, and PEEK and POKEcommands allow the interface data to beread into or from memory." It was im-portant to convince him of the true valueof high level languages. "You have a moni-tor program resident in your system thatcould allow you to just key the EROM datalist into memory somewhere, don't you?"

"Yes, but. . . ."

"No buts! Just write a BASIC prjgramthat transfers this memory table one byte ata time to the read only memory." I felt Iwas really on the move now; I was going to"learn" him something if it killed him.

"Yes, but my BASIC is an interpreter.It runs pretty slowly. It's no match for anassembly language program. Assembly lan-guage loaders can program an EROM in 100seconds; BASIC would be an order ofmagnitude. . . ." It was necessary to inter-rupt him at this point. Jerry was caught upin the old argument of potential versusaccomplishment.

"Jerry, except for the time taken fordata entry and printing, how long do youraverage BASIC programs run?"

"Oh, 5 or 10 minutes I suppose; why?"Jerry was not so curious that he had for-gotten his problem, but his responses hadbecome less acidic.

. C2708| PI219

"And what do you do in between pro-gram runs or when you go upstairs forsupper?" As oblique as my question mayhave seemed, I was driving to a point.

"I leave the computer on, of course, soI don't have to reload the BASIC. Every-body does that. Don't you?" His responsewas reminiscent of a child not sure whetherhe would be reprimanded for raiding thecookie jar or not telling that he raided thecookie jar.

"Jerry, what you just said is that if nooperator interaction is required with thecomputer, execution time is irrelevant.Furthermore, if you started a program likean EROM loader on off peak use periods,you couldn't care less if it took a minute oran hour to run."

"Yes. . .but... well, I guess you're right."He had apparently never thought to useBASIC.

"In conclusion, Jerry, what language areyou best able to program?" I had to becareful I didn't come across too strongly,but it was never too late to learn.

"BASIC, of course. I know how to pro-gram in assembly language, but. . .," hecontinued, still believing that there wassomething wrong about taking a differentapproach to the accepted norm.

"Then program the bloody EROM inBASIC! In fact, I had the same problem afew weeks ago and built the interface boardalready. If you drop over to my house thisevening, I'll show you how it works and giveyou an EROM." The look on Jerry's facewas one of relief, but I was sure he'd even-tually realize I could have answered hisquestion when he first walked in. It was

Photo I: A closeup of a2708 erasable read onlymemory. Visible throughthe transparent quartzwindow are the two banksof FAMOS (Floating gateAvalanche Injection MetalOxide Semiconductor)storage devices. The con-tents of this memory stor-age circuit are erased byexposing the window toultraviolet light.

BYTE March 1978

85

important that he understand what he wastrying to accomplish as well as obtainsatisfactory results.

This seems like an overamplified introduc-tion to a simple construction article, but Ifind it easier to present such topics if Iexplain how I got involved with them.There's no reason that read only memoryprogrammers should remain as black magicto the personal computer enthusiast. Thereare a number of 2708 EROM programmerson the market in the $100 to $150 range.But most of the readers who correspondwith me say they only want to program oneor two for bootstraps and the like. It is forthis reason I'd like to present a $9 EROMloader which, when tied to parallel portssuch as those described in a previous article(November 1977 BYTE, page 10), canprovide this function. Rather than be com-pletely confusing, maybe I ought to startat the beginning.

What Is an EROM?

If you presently own a personal computer,even in its minimum configuration, it con-tains programmable memory. Most likely thememory you own is made of semiconductormemory chips configured as boards with 4 K,8 K, 16 K or more bytes. Programmablememory means that any element can beaddressed and read from or written to (thatis to say, programmed) individually.Addressing is random and is determined byprogram necessity rather than configuration.Any number of electronic elements canfunction as programmable memories. TTL7474 flip flops, bistable relays, corememory, etc, can all function in this manner,but are not necessarily cost effective forpersonal computer applications. Since themajority of programmable memory storagein personal computers is of the semi-conductor type, one major problem iscreated. Semiconductor programmablememory is volatile. When the power isremoved, the data is destroyed.

One solution to the volatility of semicon-ductor programmable memory is to con-figure a certain quantity of the storage asnonvolatile read only memory (ROM).ROMs exhibit the same random addressingcapabilities as volatile programmable mem-ory, but the data stored in them is perma-nent. The required bit patterns are pro-grammed into them during manufacture, orduring a special postmanufacturing pro-cedure, and any time power is applied, thesebit patterns will be the same. Most computersystems containing read only memory usethis vehicle to store bootstrap loaders or

monitor routines that allow ease of systemstartup.

A further extension of the read onlymemory is the programmable read onlymemory, or PROM. When a programmableread only memory comes from a manu-facturer, no program data is stored in thedevice. To use this type of read onlymemory, a special programmer is requiredto alter the internal structure of the chip andimpress specific bit patterns permanentlyinto the addressable memory locations.

It is often desirable to have the non-volatility of ROMs and the read and writecapabilities of semiconductor programmablememories. An effective compromise is theEROM or erasable read only memory. It isused as a read only memory for extendedperiods of time, erased occasionally andreprogrammed as necessary. Erasure isaccomplished by removing the EROMintegrated circuit from the system andexposing the chip (covered by a transpar-ent quartz window) to ultraviolet light. I'lldescribe erasure and programming later.

The erasable read only memory tech-nology used by Intel and most other manu-facturers is a stored charge type calleda FAMOS transistor, for floating gateavalanche Injection metal oxide semi-conductor. It is similar to what is known asa P-channel silicon gate field effect transistorwith the lower, or "floating," gate totallysurrounded by an insulator of silicon dioxide.The 1 or 0 storage value of the FAMOS cellis a function of the charge on the floatinggate. A charged cell will have the oppositestorage output of an uncharged cell. Byapplying a 25 V charging voltage to selec-tively addressed cells, particular bit patternsmaking up the program can be written intothe memory. This charge, because it is sur-rounded by insulating material, can last foryears. When this silicon dioxide insulator isexposed to intense ultraviolet light, itbecomes somewhat conductive. The result iserasure of all programmed information asthe charge leaks away.

There are many erasable read onlymemories on the market: 1702s, 2708s and2716s are the major ones. For the most part,experimenters have moved away from thevery difficult-to-program 1702s toward themore desirable and more easily programmed2708s. An added benefit is the fourfoldincrease in storage capacity of the 2708.The 2716 is the newest version of thiserasable technology on the market, and atthe time of this writing is considerably moreexpensive than the 2708. It is for this reasonthat the methods outlined in this article areused for programming 2708s.

86

BYTE March 1978

Fastest S-100 Dynamic Memory

5Mhz D-32 Dynamic Memory Board

The D-32 is thefastest S-100 memoryboard available.

Highest Speed

The D-32's high speed is basedupon precise control of liming andconservative design. It operates inS-100 bus systems with cycle timingindependent of the bus.

Memory cycle timing is derived from aprecision digital delay line, which isfour times more accurate than othertechniques. Power consumption isminimized by the performance ofdynamic refresh cycles only whenrequired and by timing them with a35khz oscillator. During normalprogram execution, refresh cyclesoccur following instruction fetch (Ml)cycles, and are fully transparent.

Maximum Reliability

The D-32 is as reliable as staticmemory boards, since close attentionhas been paid to the properengineering discipline to maximizereliability. These details include: theuse of molded ceramic bypasscapacitors for superior noiseimmunity, keeping trace lines to theedge connector to a minimum tosuppress noise spikes on the bus,precisely-controlled timing and amulti-layer PC board with internalpower and ground planes for superiornoise immunity.

Expandability

The D-32 has a fully-transparent,dynamic refresh. Each 4096 byteblock is addressable at any 4K pageboundary. Extended addressselection allows expandability to onemegabyte co-resident in the system.

MEMORY READ

REFRESH CYCLES OCCUR TRANSPARENTLYFOLLOWING Ml CYCLE READ ONLY WHENREQUIRED BY INYERNAL REFRESH TIMING CIRCUIT.ACCESS YIME YA= 26 0 nice FROM PSYNC(MAX)

MEMORY TIMING IS PRECISELY CONTROLLED USINO A YAPPED

2S0m0IGITAL DELAY LINE TIMING SHOWN ISFOR T0L>

2PU- 2 RUNNING AY 4i*nl ( Y-CVCLE = 2SOni}

MEMORY WRIYE CYCLES ARE INITIAYEO BY YHC LEAOING

EDGE OF MWRITE PULSE.

MEMORY READ CYCLES BEGIN AY THE LEADING

EDGE OP PSYNC I OR PSYNCOllWHtH SMtMR-l

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Immediate Availability

The D-32 is immediately availableat more than 125 TDL dealersnationwide. They will show you thisfully-assembled, tested and burned inD-32. If your dealer doesn't carry TDLhardware/software products, writeor call:

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609-921-0321

Cable Address: XITAN PRIN • TWX 510-685-9280

TECHNICALDESIGNLABS

Circle 123 on inquiry card.

BYTE March 1978

87

a I3K

~ VW-

,1/xF

IC3

74121Ims

LED * „ +5v

i=aR

cs

PROGD7D6D50403D2DlDO

TT

%H

sg

470fl +iv

m

-<J B7-<5 B6-<!] B5-O B4

$

^Js.

-<i B3-0 B2-<3 Bl-<i BO

OUTPUT) PORT' NO. 16

► IOK

I TYPICAL FOR 8

-Lt>B7-OB6-OB5-OB4-C>B3-0>B2

-Obi-Obo

INPUT> PORT' NO. 16

IC52708

ALTERNATE27V SUPPLY

'I'M'M'K-

-O +27V

tJ_IO^F•35V

-C3> GND

Figure I: A 2708 erasable read only memory reader and programmer. During reading, the 2708 (IC5) receives a 10 bit addresson address lines AO thru A9. The eight bits of data stored at that location will then appear as outputs on lines DO thru D7. Thecircuit is shown attached to three 8 bit output ports and one 8 bit input port of a microcomputer. (The port numbers chosenare peculiar to the author's system and are necessary to fully describe the software interaction.) During programming, bit B6 ofoutput port 18 is set high, which causes the interface to enter the write mode. This signal raises the voltage level on the 2708select pin 20 from a 0 V read enable to a +12 V program mode enable. The eight data output lines now become data inputlines. The program mode signal also gates output port 16 through ICs 1 and 2 to these data input lines and presents the data tobe stored to the 2708. Each 8 bit data byte is then burned in for 100 ms in 1 ms pulses using ICs 3 and 4.

+5 V

-5 V

+12 V

Gnd

IC

Type

Pin

Pin

Pin

Pin

1

74125

14

7

2

74125

14

7

3

74121

14

7

4

7407

14

7

5

2708

24

21

19

12

Notes:

1. All resistors are 1/4 W 5% unless otherwisenoted.

2. Transistor Q1 is rated for VCE = 40 V. Sug-gested type: 2N2222A.

3. Note that IC4 is a 7407. A 7417 should notbe substituted.

4. Programming pulse voltage should be between25 to 27 VDC.

Output Port 18

B6 B7

0 X

1 0

1 _r

Read.

Program mode enabled.

Low to high transition. Initiatesinput byte storage into EROM.

("X" indicates a "don't care" condition.)

Programming a 2708

The 2708 is an ultraviolet erasable readonly memory. It is configured as 1024 singlebyte memory locations (eight bits per byte).Figure 1 illustrates a simple interface thatallows the user to both read and program a2708.

When reading the contents of thememory, a 10 bit address is presented toaddress lines AO thru A9, and the eight bitsof data stored in that location will appearas outputs of the memory on DO thru D7.The interface is attached to three 8 bitoutput ports and one 8 bit input port. 10 bitaddressing is accomplished by using two bitsof port 18 in addition to the eight bits ofport 17. When B7 and B6 of port 18 areat a zero level, the 8 bit stored data is readby input port 16. The port numbers chosenare peculiar to my system. Any four userdefined available parallel IO ports thataccomplish the same functions can be choseninstead, substituting for the ports I used.

Programming is straightforward. B6 ofthe output port 18 is raised to a 1 level to

88

BYTE March 1978

set the interface to the write mode. Thissignal raises the voltage level on the 2708chip select pin 20 from a zero volt readenable to +12 V program mode enable. Theeight data output lines now become eightdata input lines to the memory. The pro-gram mode signal also gates output port 16through a pair of 74125s to these data inputlines and presents the "data to be stored"to the 2708.

According to the manufacturer's specifica-tions for the 2708, it takes 100 seconds tofully program or "burn in" the EROM. Alittle simple division would lead one tobelieve that each address byte should beprogrammed for 100 ms. Yes and no! Eachbyte has a cumulative programming time of100 ms, but it is done in 1 ms pulses. Alladdresses must be cycled through the pro-gram sequence before repeating the pulse ona particular location. In plain English, aseach byte is addressed it is given a 1 msprogram pulse. To accumulate 100 ms perbyte, the program must be repeated 100times. More on this later.

IC3 and two sections of IC4 provide the+25 V program pulse to the 2708. IC3 is setfor a duration of 1 ms and is triggered by alogic 0 to 1 transition at its input. The 2708both sources and sinks current through pro-

gramming pin 18, so a combination ofdevices is necessary rather than a simpleopen collector driver. In the write mode,when CS/WE pin 20 is at +12 V and betweenprogramming pulses, pin 18 has to be pulleddown by an active device because it sourcesa small amount of current. The 1 ms pro-gramming pulse itself is about 30 mA andcannot be easily accommodated withoutemitter follower configured Q1. This pulseshould be between 25 and 27 V at pin 18.Three 9 V transistor radio batteries willsuffice for this application or a commercial24 V, 50 mA power supply can be used.Most supplies can be resistor trimmed toproduce the desired 25 to 27 V.

Using the Interface with BASIC

The logic behind this interface is simple:set an address and read data, or set anaddress and write data. Every EROM pro-grammer I have seen uses an assemblylanguage routine to sequence the operation.This interface is no exception. It will runfaster if controlled in that manner, especiallyif wired to the memory bus for read opera-tions rather than through IO ports. It doesnot have to be controlled through BASIC.

BASIC is the predominent high levellanguage in personal computer use today.

Photo 2: A 2708 pro-grammer built from thecircuit in- figure I. Thisboard uses parallel IOports to set data andaddress.

BYTE March 1978

89

100 REM FIRST WE CLEAR THE OUTPUT AND SET IT

110 REM TO THE READ MODE

130 OUT 18,0

140 FOR N=0TO3

150 FOR M=0 TO 255

155 OUT 17,M :OUT 18,N

160 PRINT "ADDRESS ";

170 NEXT M

180 NEXTN

200 END

(N*256)+M;"=";INP16

Listing 7: A BASIC program used to read the contents of an erasable readonly memory. This program and the programs In listings 2 and 3 were writtenin 8 K Zapple BASIC marketed by Micro Com.

100 OUT 18,0 :REM SET TO READ MODE110 LETX=26000 .REM

114 REM SET X=DECIMAL ADDRESS OF THE

115 REM START OF THE MEMORY TABLE120 FOR N=0TO3

130 FOR M=0TO255

135 OUT 17.M.OUT 18,N

140 POKE X, INP16

150 LETX=X+1

160 NEXTM

170 NEXTN

180 PRINT "TABLE LOADED"

200 END

Listing 2: A BASIC program used to read the contents of a 2708 erasableread only memory and store the data in memory.

90 FORT=1TO100

100 LET A=64 :OUT 18,A :REM64 IS BIT 6 SET

110 REM THIS SETS THE INTERFACE TO THE PROGRAM MODE

120 LETX=26000

130 REM X IS THE START OF THE MEMORY TABLE

140 FOR N=0TO3

150 FOR M=0TO255

155 LETD=PEEKX

160 OUT 17,M : OUT 18,N+A :OUT 16,D

165 REM LINE 160 SETS THE ADDRESS + DATA BYTES

170 OUT 18.N+A+128 :REM 128 IS THE PROGRAM PULSE BIT

180 OUT 18,N+A :REM RESET B7

190 LETX=X+1

200 NEXT M

210 NEXT N

220 LETM=0 :LET N=0

230 NEXTT

240 PRINT "DONE"

250 END

Listing 3: A BASIC program used to program a 2708.

It is only natural for an experimenter pro-ficient in BASIC to consider using thismethod. It is important to remember thatmost BASIC systems use interpreters andwill perform operations very slowlycompared with assembly (machine) languageprograms; but, if fast operation is not aparticular requirement, BASIC can performthe same functions.

Reading the contents of a 2708 is asimple procedure, as shown in listing 1.Obviously, it takes a long time to print the1024 bytes in the memory chip even thoughformatting would speed it up. Anotheroperation which is useful is to read the 2708and load it into memory, such as in the case

of a utility program or interface driver. Theconcept is the same, but the print statementis deleted. The new program, which readsthe EROM and loads it into memory, isshown in listing 2.

Programming the 2708 is no more com-plicated than reading it. There are twosources for the data to be placed in the2708. It can come from a 1 K byte listingpresently resident in memory (such as thatproduced by an assembler), or via keyboardentry. Keyboard entry, while possible, isvery time-consuming and requires that anarray be produced with 1024 variables. Ifkeyboard entry is desirable, it would be farbetter to use an existing resident monitorprogram to load memory directly from thekeyboard and produce a memory-residenttable which is then transferred to the 2708.

The program write pulse timing takesadvantage of the fact that BASIC is slowerthan assembly language. To load a memorywith data, output port 18 bit B6 is set toa logic 1 level. This enables the programpulse generator, IC3, and data input sourcethrough the 74125s. After the address anddata words are sent to the outputs, port18 bit B7 is raised to a logic 1, causing theoneshot to fire. The duration of the pulseis 1 ms. If this were an assembly languageprogram, a timing routine would haveto be used to time out 1 ms before steppinginto the next address and data combination.BASIC takes approximately 5 ms tointerpret and execute each of the commandsused in this program. With such interpreta-tion delays, the program can't possibly over-drive the programming sequence, and there-fore needs no timing loops. As stated earlier,to meet manufacturers' specifications, 1001 ms sequences must be performed. [If youreprogram the algorithm for another lan-guage, or use a BASIC interpreter, makesure the timing is comparable. . .CH/ Sucha program is shown in listing 3.

How About a 2 Minute 2708 Write Cycle?

This program is not very fast, and in fact,takes 30 to 40 minutes to run for the full100 loops. This is fine if you aren't in ahurry, but a better way is to write an intelli-gent programming routine. Yes, the manu-facturer states that to be absolutely sure the2708 is programmed, 100 loops should beexecuted. But, it has been my experiencewith the many 2708s I've programmed usingthis interface, that it takes only one loop.This is not to say that all devices will per-form similarily, but it does lead to someinteresting programming compromises. Elim-inate the FOR and NEXT loop at lines 90and 230 in listing 3. Next, at line 230, insert

90

BYTE March 1978

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Photo 3: An Ultra Violet Products UVS-IIE ultraviolet eraser for 2708s andsimilar erasable read only memories. This unit can hold four circuits at atime on conductive foam inside the tray.

a program that will read the data. After eachcomplete loop, read the 2708 byte by byteand compare it to the source table inmemory. If it is equal, then stop. Program-ming is done. If any one or more bytes donot correspond, return and sequencethrough another complete program cycle. Inmy experience with premium 2708s, I haveyet to require a second loop. This will allowfast temporary writing for program checkout.When the software is finalized, reprogramthe 2708, when time allows, with the fullTOO loops to ensure longevity of the storeddata. While conceptually it may seem morefeasible to rewrite only errant data bytes, inpractice this is not advised.

Erasing an EROM

When 2708s are bought directly from amanufacturer they come completely erased(every byte is hexadecimal FF). If you planto write a 2708 program once and you eitherdon't want to modify it or you don't makemistakes, forget about erasing. The majorityof experimenters will undoubtedly want toreprogram 2708s and similar erasable readonly memories. It then becomes necessaryto know how to erase them. We all knowthat the 2708 is ultraviolet erasable. How-ever, duration, distance from the lightsource, and intensity determine the qualityof the erasure.

People concerned about maintaining

manufacturer's specifications during the pro-gramming sequence should also be advisedof the proper erasing methods. Unlike thetest-read-after-write loop method for pro-gramming, 2708s are usually removed fromthe circuit during erasing. It is thereforeadvisable to perform the procedure correctlyor it will have to be repeated.

The typical 2708 can be erased byexposure to high intensity shortwave ultra-violet light with a wavelength of 2537 A.The recommended integrated dose (ultra-violet intensity X exposure time) is 12.5Watt-seconds per square centimeter(Ws/cm2). The time required to producethis exposure is a function of the ultravioletlight intensity.

Choice of a particular ultraviolet erasershould be equally divided between cost andsafety. A commercial unit not only specifiesits intensity (which allows computation ofexposure time), but also includes some veryimportant interlocks. It is conceivable thatsome homebrew erasers might have impropershielding that can allow the ultraviolet lightto escape or be accidently turned on whilebeing viewed. Such possibilities can lead topermanent eye damage.

One of the most cost effective eraserson the market is the UVS-11E by UltraViolet products in San Gabriel CA. This$59.50 unit is made especially with thehome computer market in mind and includessome very important safety features. Thelamp will not operate unless properly seatedin its holding tray and, if lifted from thetray, will automatically shut off. At thestandard exposure distance of 1 inch(2.54 cm), the UVS-11E produces an inten-sity of 5000 uW per square centimeter(uW/cm2). Exposure time for the 2708 iseasily calculated. Exposure time (Tp):

TE = J/l

where:

J = required erasure density of device,I = incident power density of eraser.

For a 2708 which requires 12.5 Ws/cm.I = 5000uW/cm2,J = 12.5 Ws/cm2,

-r - 12.5

5000 X10"6

2500 seconds;

or

T|r = 41.6 minutes for completeerasure.

92

BYTE March 1978

Circle 11 5 on inquiry card.

In Conclusion

"Well, Jerry, it wasn't all that bad, was it?We got your 2708 programmed with plentyof time to spare and now you know howeasy it is to do it yourself." I sensed he feltrelieved that he didn't have to cancel hisgrand computer expo for the computer clubthat evening.

"Thanks, Steve. I knew that anyone withas much computer junk in his cellar as youhave had to have the solution to my prob-lems. It's so much easier when you'reworking with someone experienced in thesematters."

The temporary glow produced by his firststatement quickly subsided. I got thisstrangely familiar tinge of pain as I startedto recognize the now familiar line. Other co-workers had involved me in computer gam-bling and stock market schemes that turnedinto real fiascos. Rather than argue in mydefense, I just shrugged off the desire to takethe 2708 back from Jerry, throw it on thefloor, and jump on it. How do I get myselfinto these things? Sanity prevailed and Ijust said softly, "We'll see."

Next month: remote AC control."

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Circle 15 on inquiry card.

BYTE March 1978

93

Continued from page 83

Figure 6: The convergencepattern of retinal ganglioncell (RGC) units on athalamic cell, showing thespatial relations of thereceptive fields of theRGCs which project tothe same thalamic cell.

Figure 7: The pattern ofconvergence of thalamiccells onto a corticaloriented line detector(simple field cell). Thespatial relations of thereceptive fields of thethalamic cells which pro-ject to this cell in anexcitatory manner is sochosen that their ownexcitatory regions lie ina straight line.

TO

VISUAL

CORTEX

RECEPTIVE AREAS OFVISUAL FIELD FOR RGCsCONVERGING ONTHALAMIC NEURON

NEURON OFLATERALGENICULATENUCLEUS OFTHALAMUS

they have response patterns rather similarto the RGCs. That is, central spots andoppositely acting surrounding rings, etc.The active fields tend to be somewhatlarger, but it appears that the thalamiccells receive positive inputs from RGCswhose positive centers are close together,so that essentially the same pattern is main-tained. This is illustrated for a typical "on-center, off-surround" thalamic cell in figure6. Actually, at this level there is a great dealof additional processing going on that hasto do with modifications on the basis ofdata returning from the cortical areas towhich the thalamic cells project, and alsodata from other brain regions which haveinput to the visual analysis system. Weshall speak more of these other inputs later,but for now we shall follow our line detectorsystem on to the cortex.

The axons of the thalamic cells makecontact with a class of cortical cells known

OVERLAPPING INHIBITORYSURROUNDS OF SELECTEDTHALAMIC CELLS'RESPONSE FIELDS

as "simple field cells." These cells typicallyrespond preferentially to more complexstimuli, such as lines of light at particularinclinations, and particular locations.Usually, it is found that a column of corticalsimple field cells deals with the analysis ofsome small area of the retinal image, andcontains a large number of such lineanalyzers. Each is responsive to a line at aslightly different angle, but all are concernedwith the same small area. Figure 7 showshow such a line detector can be constructedfrom the output of the thalamic cells. Whatis required is that the thalamic cells whichhave a positive influence on the firing of thecortical simple field cell are selected to beones that have their own circular excitatorycenters in the visual field in a straight lineat some angle to the vertical. If the inputs toour cortical cell are so selected (selectiveconvergence), then the optimal stimulusfor firing it will be a line of light whichpasses through the excitatory central spotsof all the lower echelon thalamic cells'receptive fields. Such a stimulus will producea strong (but sub-maximal) firing in each of

OVERLAPPING EXCITATORYCENTERS OF SELECTEDTHALAMIC CELLS'RESPONSE FIELDS

CORTICAL SIMPLEFIELD CELLFOR ORIENTEDLINE DETECTION

TO HIGHERCORTICAL LEVELS

SMALL AREA OFVISUAL FIELD

REGION COVERED BYOPTIMAL STIMULUSFOR CORTICAL SIMPLEFIELD CELL

SELECTEDTHALAMIC CELLS

94

BYTE March 1978

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BYTE March 1978

95

SMALL AREA OFVISUAL FIELD

EXCITATORY

CENTER OF

ORIENTED

CORTICAL SIMPLE

FIELD LINE

DETECTOR

LINE STIMULIWHICH FAIL TOEXCITE ORIENTEDSIMPLE FIELD CELL

Figure 8: Lines of lightwhich are not optimallyplaced do not activatethe simple field cell sincethey either do not strikesensitive elements, orstrike excitatory andinhibitory areas equally.

INHIBITORYSURROUND OFORIENTED CORTICALSIMPLE FIELDLINE DETECTOR

the thalamic cells since it will intersect someof the inhibitory territory of each, but sucha sub-maximal output from each of them isthe maximal input for the cortical levelcell. Now look what happens if the line isturned at a different angle, or moved to adifferent position as in figure 8. If the angleis not aligned with the line of the "on-centers," one thalamic cell will show apositive response; but the others will not,and may have their inhibitory areas acti-vated. There is thus little input to the corti-cal line detector. If the line is kept at thecorrect angle, but moved to the side, it fallsin all inhibitory territory, or else beyondthe active region altogether. Thus, whileour simple field cell can discriminate angle,it also discriminates location.

The next level of abstraction is reachedwith the so-called "complex field cells" ofthe cortex. A typical example of one ofthese would be a cell of the type we havebeen seeking, one which would respond toa line at a specified angle, located anywherein a large area of the visual field. Such acell is easily constructed if it can OR gatethe outputs of a large number of simple

field cells, all of which respond to a line atthe same angle, but whose specific sensitivelocations with regard to retinal position dif-fer, and are spread over a wide area, asshown in figure 9. Again, certain conver-gence patterns are selectively implemented.In this case the convergence principle isparallelism.

In actuality, the connections are not sostraightforward as I have suggested; there ismuch up and down traffic from thalamus tocortex and back. There is much up anddown traffic between different levels of thecortex as well. The principle however isessentially as illustrated. By continuing thistype of operation, and by combining out-puts of different types of cells, it is clearthat feature extractors of any desired degreeof complexity could be built. Arc detectors,edge detectors and numerous other typesare already available at the simple field celllevel. At the level of more complex featureextractors, which may be in areas of cortexoutside the primary visual cortex, it is verydifficult to determine the effective stimulusfor a cell simply because of the enormousnumber of stimuli that it might respond to.In a monkey brain, for example, a cell hasbeen reported by one researcher whichresponded only to the outline of a hand.It is not necessary for us to specify allthese types of feature extractors for ourpurposes. The particular set that was mostuseful to a human's brain would probablydiffer from the most useful set for a robotbrain. It is sufficient to see the principlesby which the feature extractors can be con-structed. Let us review these.

First, it is clear that not all possiblecombinations of retinal receptor activa-

Figure 9: The ■ develop-ment of a complex fieldcell of the cortex whichresponds to lines at certainangles, but without refer-ence to spatial locationover a large retinal region.

EXCITATORY CENTERS OF SELECTED

SIMPLE FIELD ORIENTED LINE DETECTORS

(SURROUNDS AND OVERLAPS OMITTED

FOR CLARITY).

ONLY THOSE DETECTORS ROUGHLY PARALLEL

TO ONE ANOTHER ARE SHOWN

SMALL AREA OFVISUAL FIELD

AXONS OF SIMPLEFIELD CELLSSELECTED FORPARALLEL ORIENTATION

CORTICAL COMPLEXFIELD CELL FORPOSITION-FREEORIENTED LINEDETECTION

REPRESENTATIVE SIMPLE FIELDLINE DETECTORS COVERING AREAAT LEFT, SHOWING SENSITIVEORIENTATION DIRECTIONS

96

BYTE March 1978

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BYTE March 1978

97

tion are encoded by higher level cells.Rather, some types of features are settledupon as useful building blocks, and theseare encoded by cells upon which the outputsof certain lower level cells converge. Theparticular set of lower level cells is selectedon the basis of the spatial relationship oftheir receptive fields on the retina. Thisis the principle of selective convergence.Look again at figure 2; it is as if we hadabandoned such a generalized system infavor of a more limited but more economicalone by omitting some branches, and bring-ing several more from selected places to-gether at each stage. Second, the responseof the higher echelon cell is frequently finetuned by provision of lateral inhibition.That is, lower echelon cells frequently haveinhibitory projections both to their neigh-bors to either side at the same level, and tothe neighbors of the higher echelon cellto which they send excitatory projections.The arrangement of these inhibitory pro-jections is often chosen to help the celldiscriminate against stimuli which aresimilar enough to the target feature topotentially generate some responding, if notfull responding, in the cell. Thus, in thesimple cortical field cell line detector infigure 8, if the angle of the line were onlyslightly off of the desired angle, it still mightcross the on-centers of several of thethalamic cells which input to the corticalcell, and cause some considerable responsein the cortical cell. It should of course onlyactivate some other angle detector. Thisdifficulty is surmounted by the fact thatin order to cross the first cell's line of on-centers at a small angle, the stimulus wouldalso have to cross a large amount of territorywhich inhibited the thalamic cells' output.(If the angular discrepancy is large of coursethere is little problem.)

The third principle of general relevanceis related to the problem of how much inputwill be required to fire a higher echelon cell.Recall that the neurons are not functioningstrictly as AND or OR gates, in that a cer-tain percentage of inputs active is all that isrequired for firing. This ALMOST gateprinciple is one of enormous power, and weshall have more to say about its applica-tion to intelligence in a later article; but forthe moment look at what happens in thesensory system if we let the percentage ofinputs required for firing be an adjustableparameter. If we required that all the linesbe active as in a conventional AND gate,we would have a perfectly accurate system,like any good conventional computer. Wewould also have a slow and insensitive sys-tem. To get all the inputs properly set up,

we would need to wait for perfect alignmentof the image, probably close up for goodresolution, and have good illumination toavoid any marginal situations. It would beaccurate, but your ancestors would neverhave reached reproductive age if they'dhad to wait on that kind of situation beforedecoding the stimulus as a wolf. On theother hand, if we let the system be sloppyand fire feature extractors when only asmall number of relevant input lines areactive, we will get quick results, with a lotof errors. In particular, we would be unableto make fine discriminations amongst simi-lar stimuli which would activate many linesin common.

This kind of error is easily demonstrated.Briefly flash a picture of a circle with a smallpiece missing on a screen, and your subjectswill report that they saw a complete circle.Only if they get to examine the image longerwill they be able to discriminate the brokencircle from a complete one. Now clearlyboth modes of processing have their uses,and it would be nice to adjust the percentageinput requirements of the ALMOST gates tosuit the task at hand. This is done in thebrain by axons from control regions of thebrain outside the sensory system whichmake diffuse and widespread contact withlarge numbers of sensory processing ele-ments. These inputs carry no specific visualinformation, but by excitatory or inhibitoryaction they can bias the processing elementstowards or away from firing threshold, thusincreasing or decreasing the amount of inputfrom lines carrying specific informationwhich is required before firing occurs. Whenthis process is driven beyond normal limits,as with various drugs, the feature extractorscan De biased so close to firing that littleor even no input is required. The re-sult is a variety of visual distortions andhallucinations.

A fourth point worth noting is that thesystem resembles a pipelining type ofprocessor. As soon as the cells of any eche-lon have fired in response to the currentstate of their inputs, succeeding echelonsbegin dealing with that fact while the earlierechelon begins to respond to the next stateof their inputs. It is not clocked, it just alltrickles through as fast as it can, but thatonly means that some things take longer torecognize than others. There is no need forit all to be processed in lockstepped stageslike a real pipelining system. However, infor-mation can be siphoned off the line at anystage as well as being passed on to the next.If you need to catch a fast moving object,you can respond to information about itsposition, which is encoded fairly early in

98

BYTE March 1978

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BYTE March 1978

99

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the process, without having to wait for adetailed analysis of its surface markingsbased on more extensive processing.

We have emphasized the development ofa particular feature extractor to clarify theprocess involved. The emphasis on selectiveconvergence should not obscure the factthat each lower echelon cell's outputsusually go to many higher echelon cells, notjust one. Further, these outputs may be in-volved in the extraction of entirely differentfeatures at each of the higher echelon cellsto which they project. It is not the case thenthat we have a grand convergence thatstarts with a million bit byte of retinal ele-ments and gates itself down to a few highlevel cells. Rather, we come out the otherend of the process with a "byte" contain-ing even more lines than the input byte.The difference is that the bits in the inputbyte represent the spatial pattern of il-lumination on the retina in a simple pointfor point code. The bits in the output byteof the system each represent the occurrenceor non-occurrence of a complex pattern offeatures in the visual world, and can be usedto directly activate appropriate responses.Thus, the input byte and the output byteof the visual system each contain the samebasic information — the content of the visualworld. However in the output byte the infor-mation is recoded so that the bits each rep-resent highly useful pieces of informationabout the patterns occurring among the in-put bits. Referring again to figure 2, the realsituation would be one in which there wereas many cells at the top of the figure as atthe bottom, with each convergent tree lead-ing to a top level cell containing manyelements in common with other convergenttrees, just as the two shown do.

We have dealt so far only with the proc-essing of spatial patterns of retinal illumina-tion. There are many other things which aredealt with; motion detection by sequentialactivation of retinal elements is one ex-ample. Depth perception by comparison ofthe patterns from the two retina is another.One that deserves special mention here isthe handling of intensity information.This is done in the brain by use of the ana-log information in the cell's "temporalbyte." That is, each line carries one bit inthe "spatial byte" which encodes the exist-ence of some set of conditions at the retinarelated to which cells are activated. Therate of firing of the line encodes, in pulsefrequency analog form, information aboutthe strength of that activation. For lowechelon cells, this is essentially informationabout the intensity of the light falling onthe receptors. At higher echelons in the

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BYTE March 1978

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sensory system, it is information about the"degree of certainty" of the cell in questionwith regard to its identification of a feature.This information derives from both intensityand spatial information, since both higherpulse rates and more lines active will in-crease the firing of the cell. This is an ex-ample of the way in which the brain maycombine digital and analog information in asingle decision process. The nature ofwhat is being encoded by intensity atthe higher levels of the process may bebetter understood by applying the "degreeof certainty" concept to the lowest levels,where the temporal byte represents lightintensity. Obviously the low level elementhas the greatest degree of certainty that itis being illuminated when it is being illumi-nated most strongly. At higher levels,number of inputs and activity of inputs cantrade off with regard to drive on the re-ceiving cell, and this is generally appropriate,because the degree of certainty about theexistence of the feature to be decoded isincreased if there is either a broad agreementamong the inputs, or if the inputs are them-selves "very certain." In general in the brain,"He who yells the loudest has the most tosay." Since cells don't have egos, it works.

In any realistic approach with presentday hardware, this would probably have tobe modeled using a byte of several bits inplace of each single line in the brain. "Whichbyte" would be equivalent to "which axon,"and the bit pattern would carry the infor-mation carried by the temporal byte on theaxon.

Given that the number of conceptualfeatures into which the visual world couldbe subdivided is virtually unlimited, whereasthe number of available bits in the systems'output byte is merely enormous, how doesthe brain decide which features to encode?Some of it, the simplest parts, are un-doubtedly the result of evolutionary selec-tion, hardwired at birth. Much of it howeveris probably developed in response to thetype of visual environment in which the ani-mal grows up. There is evidence, for ex-ample, that if a kitten is exposed to a visualworld containing only vertical lines at acertain period of its development, its visualcortex will be rich in line detectors with anear vertical orientation, and poor in de-tectors for other orientations. Apparentlythis pattern persists throughout later life.It seems similar to a PROM.

Finally, we should mention some typesof nonvisual input to the process that carryvery specific correction information. Trythis experiment. Look across the room whilemoving your head from side to side. Notice

102 BYTE March 1978

Circle 26 on inquiry card.

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BYTE March 1978

103

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that the world seems to stay still, eventhough you are moving its image around onyour retina. Now move the image aroundon the retina in a different way. Place yourfingertip against your lower eyelid andlightly jiggle the eyeball while looking acrossthe room (keep the other eye closed). Noticethat this time the world seems to jumparound as the image is moved about on theretina. Why the difference? In both casesthe image is moving around on the retina.The answer is that movement of the imagecaused by moving the head in the usualmanner is naturally an everyday problem forthe brain in interpreting the visual world.It solves the problem by using feedforwardinformation from the motor nuclei whichcontrol the movement of the head and bodyto correct the interpretation of the relativemotion of image and retina to preciselyallow for the motion as it occurs. Since youdon't usually go around jiggling your eye-ball with your finger (I assume), your brainhas never developed a mechanism to pre-correct for doing so, and you see the mo-tion. There are more subtle nonvisual inputsto the processing too, such as your moti-vations, but these are poorly understoodand beyond the scope of these articles.

Now the hard part. How might we modelsuch a visual system with current digitaltechnology? As a start, let's examine whatwould be required of a "brute force" ap-proach if we didn't care what it cost. Itwould seem the most straightforwardmethod would be to have a set of micro-processors at each echelon modeling theactivity of each of the elements at thatlevel. Since with straight digital techniqueswe would have to code intensity on a byteof several bits length, each lower echeloninput element talking to an upper echelonunit would have to present a byte ratherthan a line. This means (say) eight linesfor each converging step and each lateralinhibition, instead of one. Each processorwould then accept a number of bytes fromelements at a lower level, which it wouldprocess according to a small ROM program,and a number of bytes laterally from itsneighbors, which data would also figure inthe result. The ROM program would deter-mine the type of response of the "cell,"and its output would be a byte on a busthat ran to a number of yet higher echelonprocessors, and laterally to its own neigh-bors. If we really wanted to model thebrain's operation, this would all be con-ducted with handshaking logic and theprocessors would all have their own privateclocks. Each processor would simply con-tinually compute the result of whatever

104

BYTE March 1978

Circle 128 on inquiry card.

OSBORNE &> ASSOCIATES, INC.

The World Leaders In Microprocessor Books

If you want information on microprocessors, begin withthe Osborne books.

PROGRAM BOOKS WRITTEN IN BASIC

Payroll With Cost AccountingAccounts Payable And Accounts

ReceivableGeneral Ledger

These books may be used independently, orimplemented together as a complete ac-counting system. Each contains programlistings, user's manual and thorough docu-mentation. Written in an extended versionof BASIC.#22002 (400 pages), #23002", #24002*

Some Common BASIC Programs

76 short practical programs, most of whichcan be used on any microcomputer with anyversion of BASIC. Complete with programdescriptions, listings, remarks and exam-ples.#21002 (200 pages)

ASSEMBLY LANGUAGE PROGRAMMING

8080A/8085 Assembly LanguageProgramming

6800 Assembly LanguageProgramming

Assembly language primers in the classicalsense, these books treat assembly languageas a means of programming a microcom-puter. Full of simple programming examples.#31003(400 pages), 32003*

8080H/8085

flsscmBLV LHfiGunGe pnoGiifimmifiG

I R. Icvcnthol

AN INTRODUCTION TO MICROCOMPUTERS

* AN iNTiinouunm;

c*

Volume 0 - The Beginner's Book

If you know nothing about computers, thenthis is the book with which to start. It tellswhat computers are all about and describestheir component parts. When you've readthis, you'll be ready for Volume I.#6001 (300 pages)

Volume I — Basic Concepts

The world's best selling computer text de-scribes those characteristics common to allmicroprocessors yet specific to none. Allhardware and programming concepts youwill ever need to know are explained at anelementary level.#2001 (350 pages)

Volume II — Some Real Products(revised June 1977)

Every common microprocessor and all sup-port devices are described. Only data sheetsare copied from manufacturers. Major chipslice products are also discussed.#3001A (1250 pages)

PROGRAMMING FOR LOGIC DESIGN

;' ■■ " •

8080 Programming For Logic Design6800 Programming For Logic DesignZ80 Programming For Logic Design

These books describe the meeting groundof programmers and logic designers; writtenfor both, they provide detailed examples toillustrate effective usage of microprocessorsin traditional digital applications.#4001, #5001, #7001 (300 pages each)

OSBORNE & ASSOCIATES, INC. • P.O. Box 2036 • Berkeley, California 94702

DEPT. 16

6001 Volume 0 — The Beginner's Book

2001 Volume I — Basic Concepts

3001A Volume II —Some Real Products

4001 8080 Programming For Logic Design

5001 6800 Programming For Logic Design

7001 Z80 Programming For Logic Design

31003 8080A/8085 Assembly Language Programming

21002 Some Common BASIC Programs

22002 Payroll With Cost Accounting

PRICE

12.60

QTY

• 6-1/2%, SF Bay Area residents only

• 6%, California residents outside SF Bay Area

• Payment must be enclosed for orders of

10 books or less,

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Please notify me when it is published:

D 23002 Accounts Payable and Accounts Receivable

D 24002 General Ledger

D 32003 6800 Assembly Language Programming

Please send information on:

□ consignmentD dealer discount

□ foreign distributors

F3

Circle 86 on inquiry card.

BYTE March 1978

105

Circle 78 on inquiry card.

H8 &TRS-80

SOFTWARE

ORDER-

DESCRIPTION

MINIMUM

PRICE

CODE

SYSTEM

EACH

HEATHKIT

'H8 SOFTWAREDenton Harbor Basic Games

H8-BG1

BIORYTHM. CHOHPr TEASERf DATUMCRAPSf TRAP. 23-MATCHES> NUMBER

DHB-8K

$10

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H8-BG2

SNARK. REVERSE. STARS. TAXMANFIPFDPf SLOTS, HURKLEi MUGWUMP

Machine Lan^uade Games (Front F'ane

BHB-8KI)

$10

oo

HB-MG1

Manipulation Games

MEM-4K

$10

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H8-MG2

Number Games

MEM-IK

$10

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H8-MG3

Casino Games

MEM-4K

$10

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H8-MG4

Calculator I ClockMachine L3nauaae Programs

MEM-IK

$10

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H8-CODE

Ham Code Practice Program

(Front F'anel % Terminal Versions)

MEM-4KTRM-4K

$10

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HB-KING

Kingdom Game

TRM-4K

$10

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H8-DISM

F'roaTam Disassembler

TRM-4K

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H8-EDUC

Educator-8080 Teaches machineprogramming interactively

TRM-4K

$10

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RADIO SHACK*TRS-80 SOFTWARE

Level One Basic Games and Programs

R8-BG1

BIORYTHMf CHOMP. TEASER- BATUM

L1B-4K

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CRAPSr TRAP, 23-MATCHES. NUMBERRB-BG2 SNARK, REVERSE, STARS, TAXMAN L1B-4K $10.00FIPFOP, SLOTS, HURKLE, MUGWUMP

legend:

DHB-8K

= H8+8K+H9/H36

Uses Benton Harbor Basic

MEM-4K

= HB+4K ONLY

Uses Front F'anel

TRM-4K

= H8+4K+H9/H36

Interactive thru Terminal

L1B-4K

= TRS-80+4K

Uses Level I Basic

Includes I Cassette. Source Listing and User DocumentationTerms! Check. Money Order. BAC/YISA. Master-Chsl - NO CODs!Foreign orders in US funds. plus *i US/Cassette F'ostaaeShipment I In seauence as received by UPS or 1st Class MailDealer Inaui ries Invited* Pros!ram Contributions Sol icitedHighest Royalties Paid

Multi-Micro Media Corp.. P.O. Box 1025

Arv

Cole

80-103A Serial I/O and FSK modem forprofessional and hobby communications.

u

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u

• Completely compatible with your IMSAI, ALTAIR*SOL** or other S-100 microcomputers.Trademarks of *MITS, **Processor Technology

• Designed for use on the dial telephone or TWXnetworks, or 2-wire dedicated lines, meets allFCC regulations when used with a CBT coupler.

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• 90 day warranty and full documentation

PRICES Bare Board and Manual 49.95

Assembled (48 hour burn in) 279.95

Master Charge or Visa accepted.

DC Hayes Assoc.

P.O. Box 9884, Atlanta, Ga. 30319, 404/231-0574

inputs it had available at any instant andoutput the result. When the input from anyof its information sources changed, theoutput would change. With a processor anda ROM to represent each cell, such thingsas the weighting of percentage input froman ALMOST gate action, and the continuousalteration of output on the basis of the out-put of lateral neighbors, are simple. Such asystem would be fast, powerful, and in-credibly expensive. Let's say we opted fora minimal system running off a 64 by 64grid of photosensitive elements. Furtherlet's say we want to keep the ratio of inputto output at each echelon approximatelyunity, so we wind up with about 4,000highest echelon feature extractors. (Notbad; that means the system can recognize4,000 different complex stimuli.) Then let'ssay we want to carry the analysis to a depthof five echelons. (That determines the com-plexity of the stimuli which can be extractedby the highest level. Remember that thebrain only took four echelons to get to thecomplex field cell. Hypercomplex cellscan handle some very advanced extractionproblems.) At this point, however, we aretalking about 20,000 processors. Even at8008 prices, that's not exactly cheap.

Now suppose we try to trade speed forcost. The system just described obviouslyruns much faster than the real brain. A firststep might be to have single processors ateach echelon doing the work of many, evenall, of the 4,000 elements at that echelon.Suppose we could update the output of asingle simulated element in 100 /is. Thatmeans we could do all 4,000 in each echelonin about half a second. That's not too bad;it's still pipelining the processing from eche-lon to echelon, so the system would see apicture updated every half second with a(Vi second x number of echelons) delay be-tween the stimulus event and the finalanalysis. Even if we pulled some informationoff the pipeline early for rapid action,however, it's still too slow for real timework. (If you ever have the equipment athand, try playing catch in a room illu-minated with two per second strobe lightflashes. Anything below ten per second getsdifficult.) Two complexities also appearwhen we try to update the simulated ele-ments of an echelon serially. One is that theprogram for each element is different, whichmakes our ROM a little more complex. Theother is that the output of each elementin the array depends in part on the currentoutput of its neighbors, including the onesyou haven't gotten to yet in the currentpass. With only one pass across the arrayper update, a "lateral lag time" error would

106

BYTE March 1978

Circle 51 on inquiry card.

THE SSB ISOFLOPPY DISCOUNT

5*3-

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Affordable

The tribe at Smoke Signal Broadcasting took ourBFD-68 disk system and scalped the price, butnot the features to create the ABFD-68 (AffordableBasic Floppy Disk). We appreciate the fact thatthe computer hobbyist gave us our start and wehaven't forgotten you.

$649 Assembled

Compare Price. OurSS-50 bus compatible disksystem is $150 less than the assembled price of theleading S-100 disk system. And you can at leastdouble that savings when you buy one of thecomputers manufactured by MSI or SWTPC thatuse the superior 6800 microprocessor.

Programmable

The BFD-68 is well known for its fine software. Thesystem comes with the best disk operating systemavailable and we offer a multitude of other com-patible software products. These include a BASICinterpreter with diskfile handling capability. Bythe way, our DOS now easily handles true randomaccess files as well as sequential. Also, we have asuper fast BASIC compiler for business applica-tions. In addition, a Text Editor, 2 Assemblers, a

Trace Disassembler useful for program debuggingand an Object to Source Code Generator are allstock items available for immediate delivery.A word processor will be available very soon.

Reliable

We delivered ourfirst mini-floppy disk system ayear ago — 6 months ahead of any other 6800based mini system. Thus, we've had twice theexperience in building reliability into the system.Our NEW disk controller was designed using allwe have learned in the past year about systemreliability.

The ABFD-68 contains all the built in reliabilityof our regular BFD-68 plus you save money bysupplying your own cabinet and power supplyforthedisk.

Available

We've shipped literally tons of our BFD-68 disksystem in the past year and have learned to keepour production up with demand. Give us a call andchances are we'll be able to ship you the newABFD-68 from stock and charge it to your MasterCharge or Visa card. Better yet, ask us for the nameof the computer store nearest you that carries ourcomplete line of computer products.

Circle 106 on inquiry card

P.O. Box 20 17, Hollywood, CA 90028 • (2 I 3 ) 462-5652

BYTE March 1978 107

Circle 18 on inquiry card.

MA TR1X PRINTER

•

SIOO Bus Compatable • Inexpensive

•

40 Characters Per Line • Reliable

•

90 Lines Per Minute • Dependable

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Type Fonts — Script - Examples & Instructions

Justification - Generate • Uses Plain Paper

Any 7 Dot Matrix • Kit $375

Symbols or Characters

$426.80 COMPLETE (Assembled)

DISKETTE INTERFACE

•

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•

Uses FD1771 With • Minifloppy Drive $355 each

On-Board Crystal * SA800 Drive $595 each

•

Simple - easy to program • SA801 Drive $610 each

•

Handles up to 4 Drives • IK On-Board PROM and

•

Just Plug in Interface, CP/M Software $100

Hook Up Drive and Run Your Program

VISA • MASTER CHARGE - CHECK - MONEY ORDER

GEORGIA RESIDENTS ADD 4% SALES TAX

CENTURY DATA PRODUCTS, INC.

1758 TULLY CIRCLE NE / ATLANTA, GEORGIA 30329

404/325-7878

THE BETTER BUG TRAP

Altair/IMSAI compatible board catches program bugs andprovides timing for real-time applications.

Four hardware breakpoint addresses. Software breakpointsonly possible at instructions in RAM. Better Bug Trapbreakpoints can be in ROM or RAM, and at data orinstructions in memory, input/output channels, or stacklocations.

Board can stop CPU or interrupt CPU at a breakpoint.

Real-time functions: watchdog timer, real-time clock (fortime of day clock), interval timer.

Sophisticated timesharing made possible!

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All this and more for about the price of a real-time clockboard, but nothing else does the job of the Better Bug Trap.

$180, assembled and tested. 2 manuals plus software. 90 daywarranty. Shipped UPS. Delivery from stock.

jfffiittonitB

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P.O. BOX 12545RALEIGH, NC 27605

be introduced. Correcting this with thesimple expedient of iterative passes takes toolong. Furthermore, you have to carry someinformation in scratch pad. How far do youwant elements to be able to interact later-ally? For most purposes, a few elementsaway might do, but for some tasks such asmotion detectors, the brain converges out-puts from widely separated elements. Lateralinteraction among these is probably bestignored in our hypothetical simple system.Presumably, some optimization could befound in which several processors simulatedeach echelon, each one handling a number ofelements serially.

A different approach to trading speedfor cost would be to have all your availableprocessors simulate the elements of a singleechelon, store the result, switch programsand simulate the next echelon, then thenext, etc. This way you get through eachechelon faster because a complete update ofan echelon is divided among more proc-essors, and fewer elements simulated seriallyper processor means you finish quicker.However, with this scheme you lose thepipelining feature of the system, since a newinput byte has to wait until the last bytegets all the way through before the systemcan start to deal with it by simulatingechelon number one again.

These notions of course do not exhaustthe approaches to the problem, and I didn'tpromise to solve it for you, but they illus-trate some of the kinds of difficulties wecan expect to have to overcome. (Actually,I have some more advanced ideas on thesubject, but you're not going to hear aboutthose until somebody offers me a vicepresidency for Psycho-cybernetic Archi-tecture!) The best approach may well notinvolve replicating the detailed features ofthe brain's processing steps in recoding thesensory input. What does seem worthstudy however is the general logic of theapproach. Specifically, this would includesuch items as: ways of eliminating redundantinformation, the logic of using selectedfeature extractors as building blocks at eachstage of the perceptual process, the elimina-tion at each level of restrictions such asposition on the generality of the featureencoding line, and the use of the ALMOSTgate concept to provide continuouslyvariable levels of stringency in the encodingprocess."

BIBLIOGRAPHY

Hubel, D, "The Visual Cortex of the Brain,"Scientific American, November 1963.

Karner, N (trans). Current Problems in Neurocy-bernetics, Wiley, New York, 1975.

108

BYTE March 1978

Circle 69 on inquiry card.

The Electric Pencil II is a CharacterOriented Word Processing System. Thismeans that text is entered as acontinuous string of characters and ismanipulated as such. This allows theuser enormous freedom and ease in themovement and handling of text. Sincelines are not delineated, any number ofcharacters, words, lines or paragraphsmay be inserted or deleted anywhere inthe text. The entirety of the textshifts and opens up or closes as neededin full view of the user. The typing ofcarriage returns as well as wordhyphenation is not required since linesof text are formatted automatically.

As text is typed in and the end of ascreen line is reached, a partiallycompleted word is shifted to thebeginning of the following line.Whenever text is inserted or deleted,existing text is pushed down or pulledup in a wrap around fashion. Everythingappears on the video display screen asit occurs which eliminates anyguesswork. Text may be reviewed at willby variable speed scrolling both in theforward and reverse directions. By usingthe search or the search and replacefunction, any string of characters maybe located and/or replaced with anyother string of characters as desired.

When text is printed, The Electric Pencil II automatically inserts carriagereturns where they are needed. Numerous combinations of line length, page length,line spacing and page spacing allow for any form to be handled. Character spacing,BOLD FACE, multicolumn as well as bidirectional printing are included in the Diabloversions. Right justification gives right-hand margins that are even. Pages may benumbered as well as titled. This entire page (excepting the large titles and logo)was printed by the Diablo version of The Electric Pencil II in one pass.

Now on CP/M

You've probably seenThe Electric Pencil in

action by now. It's themost powerful 80807Z80character oriented wordprocessor on the markettoday. Michael Shrayer isnow proud to present thenew Electric Pencil II.

NEW FEATURES:*** CP/M Compatible *** DiskOperating System Supports Two Disk Drives *** SimpleFile Management *** Quick and Easy Disk Storage andRetrieval *** Dynamic Print Formatting *** MulticolumnPrinting *** Print Value Chaining *** Page-at-a-timeScrolling *** New Bidirectional Multispeed ScrollingControls *** New Subsystem with Print Value Scoreboard*** Automatic Word and Record Number Tally *** CassetteBackup Capability *** Full Margin Control ***End-of-Page Control *** Non-Printing Text Commenting*** Line and Paragraph Indentation ***

Centering, Underlining and BOLD FACE

The Electric Pencil II is now available on CP/M. Standard printer versions $225.

Diablo printer versions $275.

System Hardware MUST include:

8080 or Z-80 Based MicrocomputerPrinter (Diablo Hy-Term, TTY, etc.)Video Display (VDM-1, VTI or SOL)CP/M Supported Disk System or...North Star Mini-Floppy Disk or...Cassette Interface (Tarbell or SOL)

SS

MICHAEL SHRAYER SOFTWARE

3901 Los Feliz BoulevardLos Angeles, CA 90027(213)665-7756

The Electric Pencil I is still available for non CP/H users as follows:

Versions

SS,SV,SPSSN,SVN,SPN

DS,DV,DPDSN,DVN,DPN

Printer

TTY or similarTTY or similarDiablo Hy-TermDiablo Hy-Term

Video Interface/Mass Storage Price

S0L/Cuter,VDM-1/Tarbell,VTI/Tarbell $100.

S0L/NStar,VDM-1/NStar,VTI/NStar $125.

S0L/Cuter,VDM-1/Tarbell,VTI/Tarbell $150.

S0L/NStar,VDM-1/NStar,VTI/NStar $175.

Demand a demo from your dealer!

r

ft

ftft

ft

ft

s

ft

Circle 103 on inquiry card.

BYTE March 1978

109

Our MacroFloppy™goes twice the distance.

For $695.

Introducing the Micropolis MacroFloppy,M:1041 and :1042 disk drive sub-systems. For the S-100/8080/Z-80 bus. Packing 100% more capacity into a5X-inch floppy disk than anyone else. 143K bytes, to be exact. For as littleas $695.

The MacroFloppy:1041 comes with the Micropolis Mod I floppy packagedinside a protective enclosure (without power supply). And includes an S-100controller. Interconnect cable. Micropolis BASIC User's Manual. A diskette con-taining Micropolis BASIC, and a compatible DOS with assembler and editor.The :1041 is even designed to be used either on your desk top, or to be inte-grated right into your S-100 chassis.

The MacroFloppy:1042 comes with everything the :1041 has, and more.Such as d.c. regulators, its own line voltage power supply, and, to top it off,a striking cover. Making it look right at home just about anywhere.

Both MacroFloppy systems are fully assembled, tested, bumed-in, andtested again. For zero start-up pain, and long term reliability. They're alsobacked up by our famous Micropolis factory warranty.

And both systems are priced just right. $695 for the MacroFloppy:1041and $795 for the MacroFloppy:1042.

You really couldn't ask for anything more.

At Micropolis, we have more bytes in store for you.

For a descriptive brochure, in the U.S. call or write MicropolisCorporation, 7959 Deering Avenue, Canoga Park, California 91304. Phone(213)703-1121.

Or better yet, see your local dealer.

?c*-*>

Circle 70 on inquiry card.

MICROPOLIS

More bytes in store for you.

Book Reviews

Chess and Computers by David Levy, Com-puter Sciences Press, Potomac MD, 1976,145 pages. Paperbound, $8.95.

Chess and

Computers

David levy

x

a

If you enjoy playing chess, then youshould thoroughly enjoy Chess and Com-puters by David Levy. This 145 page paper-bound book is loaded with chess gamesplayed by computers. The games arecomputer versus computer and computerversus human. When you settle down withthis book, it would be a good idea to setup your chessboard and play the games. Aswith any good chess book, half the enjoy-ment is found in playing along, duplicatingthe moves in these games, reading thecomments by the author, and adding yourown comments.

The initial chapter recounts two of theearly (1700s) so-called chess playingmachines. The automaton chessplayerdeveloped by Baron von Kempelen is de-tailed with much emphasis placed not onlyon the sham it produced, but also on themechanics of the machine itself. The chessplaying machine of Torres y Quevedo is alsodiscussed in this initial chapter. Althoughthis machine played a king and rook againsta rook endgame, the idea of the tree struc-ture is quite evident in the mechanics ofthe device.

Chapter 2 is entitled "How Computers

110

BYTE March 1978

TM

MetaFloppy

The Micropolis MetaFloppy™ gives you more than four times the capacity ofanyone else's 5^-inch floppy. Because it uses 77 tracks instead of the usual 35.

The field-proven MetaFloopy, with thousands of units delivered, comesin a complete family of models. And, like our MacroFloppy"J family of diskdrives, MetaFloppy is designed for the S-100/8080/Z-80 bus.

For maximum capacity, choose our new MetaFloppy:1054 system Whichactually provides you with more than a million bytes of reliable on-line stor-age. For less money than you'd believe possible.

The MetaFloppy:1054 comes complete with four drives in dual config-uration. A controller. Power supply. Chassis. Enclosure. All cabling. A new BASICsoftware package. And a DOS with assembler and editor. There's even a built-in Autoload ROM to eliminate tiresome button pushing.

If that's more storage than you need right now, try ourMetaFloppy:105S, with 630,000 bytes on-line. Or our Meta-Floppy:1043, with 315,000 bytes on-line. Either way, you canexpand to over a million bytes on-line in easy stages, when youneed to. Or want to.

In other words, if your application keeps growing, we've gotyou covered. With MetaFloppy.

The system that goes beyond the floppy.

For a descriptive brochure, in the U.S. call or write MicropolCorporation, 7959 Deering Avenue, Canoga Park, California 913Phone (213) 703-1121.

Or better yet, see your local dealer.

MICROPOLIS"

More bytes in store for you.

goesbeyond,

Circle 139 on inquiry card.

Play Chess." Needless to say, it requiresa second and third reading. Levy assumesthe reader has a basic knowledge of chessand chess playing by computer. He intro-duces the tree structure and its importanceto game playing by computer. Some of thechess ideas stressed include: center squareoccupation; mobility and quantity ofpieces; and the subtle features which makethe difference between a good and a poorchess player. Any good chess player knowsthat the secret to winning involves theability to look ahead throughout the game.In this way, the player is in a position togauge future game conditions and theirvalues to himself and his opponent. Thecomputer carries this look ahead featureto great lengths. Here is where the treestructure comes into play and Levy includesmany details of this important aspect.

Chapters 3 and 4 are historical in thatthey recount the early and modern eras ofcomputer chess. The early history of com-puter chess dates to before 1960 whilethe modern era brings us up to the mid1970s. Throughout this book, and especiallyin these two chapters, the games played bycomputer are listed. This is the time to get

out your board and play along with thebook. The remarks and the games are wellworth reading twice. As you read and playthe games listed in these two chapters, youcan see that the programs are improvedas they grow in age and wisdom.

There are more interesting games inchapter 5. Since this chapter deals withcomputer chess tournaments, you wouldexpect to see the better games played bycomputer. You won't be disappointed. Thelast two chapters concern themselves withfuture developments in the area of com-puter chess. Levy also takes time to mentionhis bet that no computer program will beable to beat him by 1978.

This book offers something for the chessplayer as well as for the computerist. Thegames are numerous and the remarks aregood. The computer jargon is interestingand nontechnical.

Len Gorney

Box 96 RD 1

Clarks Summit PA 18411"

77?e publisher has just informed us thata second volume of Chess and Computersis due to be published soon.

BYTE March 197S

111

The disk system you want

at a price you didn't expect from a

company that understands systems.

112 BYTE March 1978

THE VISTA*50FLOPPY DISCOUNT

We know that one of the biggest problems inpersonal computing is that you're buying withyour own personal dollars.

That's precisely why you're going to likedoing business with us.

We're Vista Computer Company, the personalcomputer systems brainchild of the business com-puter systems people at Randal Data Systems.

And our V80 Floppy Disk System is a perfectexample of how we're prepared to help you get themost out of your personal computing dollars.

$649 buys you thewhole kit and kaboodle

The $649 you spend on a Vista V80 FloppyDisk System ($749 assembled) gets you every-thing you need:

An 80K byte minifloppy drive (assembled andtested) that can be powered directly by your8080 or Z-80 computer. (Case and powersupply optional.)An I/O cable and asingle card, S100 bus-compatible controller kitthat handles up to fourdrives and includes a PROMfor bootstrap loading (addi-tional drives just $399).VOS, the most advancedmicrocomputer disk operatingsystem available, and ourBASIC-E compiler, designedto work with VOS, all on a

iFJ-T-SB

*9j§ i -m

■^^^m^^-

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: i

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55*»

single diskette. Software functions includeinstantaneous program loading, named dynamicfiles, program editing, assembling, debugging,batch processing, and file copying on back-updiskettes.

All backed by the Vista 90-day warranty, mem-bership in VUE (Vista Users' Exchange), andDataforce, our associated service company with115 locations throughout the country.

Test drive the V80at your local computer store

Drop by your nearest computer store and runthe V80 through its paces. Once you find out whatit can do for you, you'll see that our combinationof high performance and low price is hard to beatand easy to take.

We love to take orders

If you'd like us to ship you a Vista V80 FloppyDisk System, they're available now. Just send us acheck or money order for the amountof purchase, or your BankAmericard/VISA or Master Charge accountnumber with expiration date andauthorized signature. California resi-dents add 6% sales tax. Uncertifiedchecks require six weeks processing.

To place your order, or to obtainfurther information, call or write today.

Vista Computer Company, 2807Oregon Court, Torrance, CA 90503.(213) 320-3880.

Vi/tci

We never forget it's your pocket.

Circle 130 on inquiry card.

BYTE March 1978

113

About the Author

Dan Fylstra Is a graduate of Massachusetts Institute of Technology and asecond year student in the MBA program of Harvard Business School, con-centrating in marketing. His background includes extensive work with highlevel languages including authorship of the PLM/6800 compiler for inter-metrics Inc, and consulting on the HAL/S language and compilers for NASAand the European Space Agency. His equipment now includes a K/M-1, anOS/ system, PET 2001 and Radio Shack TRS-80.

User's Report: The PET 2001

Dan Fylstra22 Weitz St #3Boston MA 02134

Photography by Dan Comly

About a year ago Commodore BusinessMachines Inc, a well-known maker of pocketcalculators, startled everyone in the personalcomputer industry by announcing its PETcomputer, a self-contained unit with key-board, display, cassette drive and built-inBASIC for $495. The announcement wasgreeted with considerable enthusiasm andskepticism, for Commodore obviously wasstretching the state of the art in technology,manufacturing and mass distribution.

Photo I: A view of the Commodore PET, Model 2001. This personal com-puter sells for $595 and includes a keyboard, video display, cassette drive,4 K bytes of programmable memory, and a BASIC interpreter and operatingsystem in 14 K bytes of read only memory.

Now the first PETs have been delivered,and a few computer stores have begunadvertising their availability. The PET'sprice has risen to $595, and in the meantimeother personal computers with comparableprice and performance characteristics havecome on the market. Many people arewondering which computer represents thebest buy in terms of hardware and softwarecapabilities, expandability, availability anddelivery, warranty and service, and softwaresupport. If you are considering purchaseof such an "appliance" computer, thisreview should help you make your owninformed judgments on these issues.

I ordered a PET a few days after thefinished product was shown at the NationalComputer Conference in Dallas TX lastJune, and hence I received one of theearly units (apparently number 17 off theproduction line) without a completeuser manual describing everything thePET can do. By the time this is printeda better user manual should have beenpublished; so bear in mind that this isa preliminary review, written in late October1977, and based on experience with myPET, conversations with Commodore engi-neers at trade shows, and precious littledocumentation. I have not been able totest some of the PET's many features, inparticular the expansion options, due tothe dearth of information from Commodore.For a more complete picture, talk to yourcomputer dealer and, if possible, to otherPET owners before you make a purchasedecision.

General Specifications

Photo 1 illustrates the attractive overallappearance of the Personal Electronic

114

BYTE M.ircli 1978

'K

WhQ LL££jllsff to T^pta ^sfeaoma

a&

MODEL CC-8 $175.00

4800 BAUD CASSETTE RECORDER

An ASYNCHRONOUS NRZ type Recorder with remote motor start/stop. Errorrate 108 at 4800 BAUD. Can be used from 110 to 4800 BAUD into a UART or "BitBanger PIA" -no clocking required. This is not an audio recorder. It takes RS232 orTTL signals from the terminal or computer and gives back the same signals. No audiointerface is used. Motor start/stop is manual or through TTL or RS232 signals.

Tape speed is 3.2'/second nominal; 1.6"/sec. optional. 110 volt, 60 Hz, 5 watts.(220 Volts on special order). Can use high quality audio cassettes (Philips Type) orcertified data cassettes. Can be used in remote locations from a 12 Volt battery.

Recommended for DATA LOGGING, WORD PROCESSING, COMPUTER PRO-GRAM RELOADING and DATA STORAGE. Especially recommended for 6800systems, 6502 systems, 1800 systems and beginners with the 8080 systems. Manualcontrol except for motor start/stop. 6800 or 8080 software for file or record searchingavailable on request with order. Used by major computer manufacturers, Bell Tele-phone and U.S. Government for program reloading and field servicing.

AVAILABILITY - Off the shelf.

expands 6800 CONTROLLER for SWTP

.. .;.-.

IBSp

PROVIDES MONITOR AND TAPE SOFTWARE in EPROM.MIKBUG with 1 K of ADDITIONAL ROM PROGRAM.

This is a complete tape controller for the SWTP 6800 system. Has 3 K of EPROMspace for your own programs. A 1 K ROM (2708) is provided with all tape and moni-tor functions. The ROM program is identical to our extensive 8080 ROM program.

Has one ACIA for one or two tape drives, one USART for an additional Serial portand a 4 bit parallel port for motor control. Will control one or two CC-8 or 3M3Adrives with the software provided. Can be used with other tape drives controllable with4 TTL bits if appropriate software changes are made.

Extra serial port is provided for your use with a second terminal or printer. (RS232,TTL or 20 ma)

The ROM program supplements the MIKBUG program and is entered automaticallyon reset.

availability off the sheif $190.00, Tested & Assmb. ($160.00, Kit)

fc4KfS;*vA-;.«vfr>

2SIO (R) CONTROLLER$190.00 ($160.00 Kit)

PROVIDES MONITOR AND TAPE SOFTWARE in ROM TERMINAL andTAPE PORTS on SAME BOARD CONTROLS ONE or TWO TAPE UNITS(CC-8 or 3M3A)

This is a complete 8080, 8085, or Z80 system controller. It provides the terminalI/O (RS232, 20 mA, or TTL) and the data cartridge I/O, plus the motor controllingparallel I/O latches. Two kilobytes of on board ROM provide turn on and go controlof your Altair or Imsai. NO MORE BOOTSTRAPPING. Loads and Dumps memoryin hex on the terminal, formats tape cartridge files, has word processing and papertape routines. Best of all, it has the search routines to locate files and records bymeans of six, five, and four letter strings. Just type in the file name and the recorderand software do the rest. Can be used in the BiSync (IBM), BiPhase (Phase encoded)or NRZ modes with suitable recorders and interfaces.

This is Revision 7 of this controller. This version features 2708 type EPROM's sothat you can write your own software or relocate it as desired. One 2708 prepro-grammed is supplied with the board. A socket is available for the second ROMallowing up to a full 2K of monitor programs.

Fits all S100 bus computers using 8080 or Z80 MPU's. Requires 2 MHz clockfrom bus. Cannot be used with audio cassettes without an interface. Cassette orcartridge inputs are RS232 level.

AVAILABILITY - Off the shelf.

Z 80 BOARD for SWTP COMPUTER: Now you can use the 8080/Z80 software programs in your SWTP 6800machine. Replaces your MPU board with a Z80 and ROM so that you are up and running with your presentSWTP memory and MPC card. $200 assembled and tested. ($160 kit)

AVAILABLE-November '77.

.-■>.

OVERSEAS: Export Version 220 volt 50 hz. Write factory or: Megatron-Datameg, 8011 Putzbrunn, Munchen, Germany;Nippon Automation5-16-7 Shiba, Minato-Ku, Tokyo, Japan; Hobbydata, PACK 20012, Malmo, Sweden; G. Ashbee, 172 /field Road, London SW 10-9ag: Trin-tronics, Ltd., 186 Queen Street W., Toronto, Ontario, Canada; EBASA, Enrique Barges 17, Barcelona 14, Spain;ARIES, 7, rue Saint Phi/lipe duRoute, 75008 Paris; Microlem 20131, Milano, Italy; Eagle Electric, Capetown, S. Africa.

For U.P.S. delivery, add $3.00 Overseas and air shipments charges collect. N.J. Residents add 5% Sales Tax. WRITE or CALL for furtherinformation. Phone Orders on Master Charge and BankAmericard accepted.

Naticnal Multiplex Corooraticn

___j 3474 Rand Avenue, South Plainfield NJ 07080 Box 288 Phone (201) 561-3600 TWX 710-997-9530

Circle 80 on inquiry card.

BYTE March 1978

115

Photo 2: A close-up of thePET keyboard and cassettedrive. The keyboard is aflat, calculator style unitwith 73 keys. The uppercase shift positions on 64of the keys are occupiedby graphic characters. Atthe right are the cursorcontrol and insert/deletekeys and a numerickeypad.

Transactor, Model 2001 (as it is fancifullycalled). Overall it measures 16.5 inches (41.9cm) wide, 18.5 inches (47 cm) deep and 14inches (35.6 cm) high, and weighs 44 pounds(20 kg). The PET is a lot more portable thanmost computers, but you won't have tocarry it very far before you'll appreciate howheavy an oddly shaped 44 pound packagecan be. On the other hand, all the essentialperipherals are integrated into the unit, andall you need is a wall socket to power upand start typing in BASIC programs.

A powerful BASIC interpreter and anoperating system presently supporting multi-ple external peripherals are built into thePET's 14 K bytes of read only memory. Thebasic PET for $595 includes an additional 4K bytes of programmable memory, whichholds your currently running BASIC pro-gram and data. An expanded model for $795includes 8 K bytes of user memory (themaximum amount of memory inside thestandard cabinet). Thanks to the efficientencoding of BASIC statements (see below),even the basic 4 K unit can hold up to a fewhundred lines of program text.

Since Commodore had acquired MOSTechnology Inc as a captive source of its

calculator chips and other silicon require-ments, the PET is based on the MOS Tech-nology 6502 microprocessor. This may notbe of much significance to the casual usersince the machine is primarily designed tobe programmed in BASIC, but it may makea difference to the experienced hobbyistwho intends to write machine or assemblylanguage programs as well.

Display Screen

The PET includes a 9 inch (22.9 cm) en-closed, black and white, high resolution CRTdisplay which presents 1000 characters, ar-ranged in 25 lines of 40 characters each. Thedisplay is memory mapped (ie: continuouslyread out of a section of programmable mem-ory separate from the BASIC program anddata memory), and is easily controlled fromBASIC using PRINT and POKE statements.(PET owners who have not already done somay want to experiment with direct access,via POKE statements, to the displaymemory, which starts at location 32768.)

Built-in software provides a winking cur-sor and automatic scrolling from the bottomof the display. The cursor can also be moved

116

BYTE March I978

A

o

^

\

& \^*OCESSO« *0P

CP/M™ LOW-COST MICROCOMPUTER SOFTWARE

CP/M™ - Microcomputer Control Program

CP/M7" is a time-tested diskette operatingsystem for Intel 8080 or Zilog Z-80 micro-computers which use up to four IBM-compatible diskette drives. The CP/M diskoperating system, along with its system utilitiesis a proprietary software package which hasoperated in thousands of computer systemsincluding OEM products, industrial applica-tions, as well as microcomputer developmentand personal computing systems. CP/M sup-ports named dynamic files with a powerfulcontext editor for program creation andmodification and includes a fast 8080 assembler,dynamic debugger with a self-contained assem-bler/disassembler, along with various file utili-ties. Optional software includes a macroassembler, symbolic debugger, and various highlevel languages. The resident portion of CP/Moperates in less than 4K bytes, with a minimumusable memory of 16K bytes. Hardware-dependent portions of CP/M are easily adaptedto nearly any 8080 or Z-80 computer systemusing our "CP/M Alteration Guide" whichgives the step-by-step procedure for tailoringCP/M to your specific equipment.

Additional Software: A variety of additional CP/M-compatible software packages are on the market: three different disk BASICsystems are available from Digital Research and independent suppliers, which support both scientific and business applications.Preprogrammed business packages can be purchased from independent suppliers for general ledger, sorting, mailing list, and textprocessing functions. Further, an ANSI Standard FORTRAN compiler is again available through Microsoft, with more high levellanguages coming. Finally, a healthy CP/M user's group has been active for over a year, where you can obtain quality softwareavailable at a very low cost and add your own programs to a community of enthusiastic users. Write us for particulars!

MAC™ - CP/MT" Macro Assembler

MAC, the CP/M macro assembler, is upwardcompatible from our standard assembler as wellas the latest Intel macro assembler. In additionto full expression analysis, MAC allows IF,ENDIF, and ELSE groups for conditionalassembly, MACRO definitions for macrogrouping, IRPC, IRP, and REPT to repeatsource statements during assembly with option-al LOCAL symbols, and MACLIB for macrolibrary access. Macro libraries are included withMAC for assembling Z-80 instructions and forperforming sequential disk input/output. Asymbol table can be selectively written to adiskette file for program debugging using SID.The "Macro Assembler Language Manualand Applications Guide" shows you how toeffectively use macros to define macro-basedlanguages, implement high level control struc-tures, and perform operating system calls usingpredefined input/output macros. The MACmacro assembler occupies a 12K region ofmemory and requires concurrent operationwith CP/M, resulting in a minimum usablememory of about 24K.

SID'" - CP/M'"Symbolic Instruction Debugger

SID is a powerful symbolic debugger forprograms generated in the CP/M environment.Upward compatible from our standard de-bugger, SID uses symbol information producedby MAC for high level reference to memory andinstructions in the program under test. SIDexpands upon the assembler/disassembler,breakpoint, and trace features of our standarddebugger to include symbolic expressions,decoded memory locations by symbol referenceduring trace and display, 8-bit and 16-bit displayand set functions, along with "pass counts" andpermanent breakpoints. SID utility functionsallow you to monitor program "hot spots" aswell as collect traceback information from abreakpoint. In particular, the SID histogramutility shows the relative frequency of executionin various parts of a program under test so thatyou can "fine tune" for most effective execution.SID operates in a 6K region, and requiressymbol information from MAC to use the SIDsymbolic features.

Please send me the following:

□ CP/M™ System Diskette and Documentation (Set of 6manuals) for $100.

□ CP/M™ Documentation (Set of 6 manuals) only for $25.

□ MAC™ Diskette and Manual (CP/M™ Serial No. ) for $90.

□ MAC™ Manual only for $15.

□ SID™ Diskette and Documentation (CP/M™ Serial No. ) for $75.

□ Send more information on CP/M high level languages andoptional packages.

01 DJGJTflL RESEARCH

NOTE: Due to the proprietary nature of CP/M™ software, pleaseenclose your CP/M Serial No. when ordering MAC or SID without theCP/M diskette.

□□D

BankAmericard No.Master Charge No.

Exp. DateExp. Date

Check or M.O. enclosed.California residents add 6% sales tax.

Total amount enclosed

Name

AdHrpss

City

FitMp 7ip

Post Office Box 579 <

• Pacific G

rove,

California 93950

Circle 39 on inquiry card.

BYTE March 1978

117

Photo 3: A simple example of the PET's graphic capabilities. This display wascreated with a series of 23 BASIC PRINT statements. The graphics charactersin each character position run together to form the figures. The playing cardillustrates the use of the reverse field option.

commodore

Radio Shack

PET TRS-80

EITHER WAY... We've got software for you!

Show your friends what your computer can do. Learn programmingtechniques the enjoyable way—by playing and modifying these gameprograms. Just drop in the cassette and save hours of typing time. Allprograms run on 8K PETs and 4K TRSSOs (slightly simplified).

INTRODUCTORY SPECIAL: Play POKER against your computer.Match wits to corner ONE QUEEN on a graphic chessboard. Enrichyour KINGDOM amid wars, famine, earthquakes, assassinations, etc.Test your bravery as a MATADOR in a bullring. Nearly 1000 lines ofBASIC. 33% discount price until March 31 for all four $9.95

STIMULATING SIMULATIONS by Dr. C. W. Engel: Ten originalsimulation games such as Diamond Thief, Monster Chase, LostTreasure and Space Flight, complete with a 64 page illustrated bookgiving flowcharts, listings and suggested modifications .... $14.95

6502 ASSEMBLER IN BASIC (for PET only): Accepts all standard6502 instruction mnemonics, pseudo-ops, and addressing modesplus new TEXT pseudo-op. Evaluates binary, octal, hex, decimal, andcharacter constants, symbols and expressions. Uses PET line numberand cursor editing features for assembler source code. Supportsexecution of assembled programs with keyboard and display I/O.Fully documented and easily understood and modified $24.95

ORDERS: Check, money order or VISA/Master Charge accepted. Weguarantee you functioning programs, readable cassettes and promptdelivery. Our catalog, $1 or free with any cassette, fully documentsthese and other programs and describes our royalty program forsoftware authors. For a FREE flyer, use reader service card, or send aself-addressed stamped envelope for faster service.

Personal Software™

P.O. Box 136-B3, Cambridge, MA 02138VISA/MC telephone orders welcome at (617) 783-0694

in any direction using the cursor control keys(see the keyboard layout shown in photo 2),and the insert/delete key can be used to"push apart" characters on a line to makeroom for changes or to delete charactersand "close up" the space which they formerlyoccupied. These features provide a conven-ient way to modify a BASIC programwithout having to retype entire lines: justlist the lines on the display, use the cursorcontrol and insert/delete keys to makechanges directly on the display, and pressthe return key after each line is satisfactorilymodified. A key is also provided to clear thescreen or to send the cursor to the "home"position (upper left-hand corner).

Character Set

The PET's standard character set includes64 upper case alphabetic, numeric and specialcharacters, and 64 graphic characters, whichare generated by pressing the shift key andone of the regular character keys (see photo2). Each character is formed on the screen inan 8 by 8 dot matrix, and each characterposition on the screen is contiguous to thosearound it, so that graphic characters can berun together to form lines, solid areas andother shapes and figures. Furthermore,a "reverse field" feature, applicable on acharacter by character basis, changes eachwhite dot to black and each black dot towhite. This in effect gives 64 additionalgraphic characters. Any of these characters,including the reverse field and cursor controlcharacters, can be inserted into a BASIClanguage PRINT statement, so that inter-esting graphics effects can be created quiteeasily. A simple example of the PET'sgraphics capabilities is shown in photo 3.In general, the PET's graphics capabilitiesare better adapted for drawing pictures ofthis sort than for plotting mathematicalfunctions.

For the person who is more interested inalphabetic text than in graphics capabilities,the PET provides an upper and lower casecharacter set with a limited number ofgraphic characters. The lower case option,which is applicable to the entire screen atonce, is enabled by means of a POKEstatement which changes the setting of anaddress line on the character generatorread only memory. The effect is to producea lower case letter in place of the graphiccharacter which normally appears when analphabetic key is pressed in upper caseshift. (Yes, you must press the shift keyto get lower case, and omit the shift key toget upper case!) This is illustrated in photo 4.

118

HYTE March 1978

Circle 93 on inquiry card.

Order your Apple II now.

from any one of the following authorized dealers:

Computerland

3020 University Dr. N.W.

Huntsville 539-1200

The Computer Center303 B Poplar PlaceBirmingham 942-8567

ALASKA

The Alpha Corporation100 W. Inf. Airport Rd.Anchorage 279-1316

Team Electronics

Anchorage 276-2923Anchorage 272-4823Fairbanks 456-4157ARIZONAByte ShopTempe 894-1129Phoenix 942-7300Tucson 327-4576CALIFORNIA

A-VIDD Electronics2210 Bellflower RoadLong Beach 598-0444

Byte Shop

Citrus Heights 961-2983Palo Alto 327-8080Pasadena 684-3313San Jose 377-4685San Mateo 341-4200Santa Clara 249-4221Walnut Creek 933-6252ComputerlandElCerrito 233-5010Hayward 538-8080Inglewood 776-8080Mission Viejo 770-0131San Diego 560-9912San Francisco 546-1592Thousand Oaks 495-3554Tustin 544-0542Computer Components5848 Sepulveda Blvd.Van Nuys 786-7411

Computer Country506 E. 1st. St.Tustin 838-4770

Computer Playground

6789 Westminster Avenue

Westminster 898-8330

Computer Store

1093 Mission St.

San Francisco 431-0640

The Computer Store

820 Broadway

Santa Monica 451-0713

Electric Brain

3038 N. Cedar Ave.

Fresno 227-8479

Home Entertainment Emporium

2100 Sepulveda Blvd.

Manhattan Beach 546-2501

Rainbow Computing. Inc.

10723 White Oak

Granada Hills 360-2171

Strawberry Electronics

71 GiennWay #9

Belmont 595-0231

COLORADO

Byte Shop

3464 S. Acoma St.

Englewood 761-6232

Team Electronics

Boulder 447-2368

Colorado Springs 596-5566

Fort Collins 484-7500.

Grand Junction 245-4455

Greeley 356-3800

Longmont 772-7800

Pueblo 545-0703

CONNECTICUT

Computerland

2475 Black Rock Turnpike

Fairfield 374-2227

The Computer Store

63 S. Main St.

Windsor Locks 627-0188

DELAWARE

ComputerlandKirkwood HighwayNewark 738-9656

FLORIDAByte Shop

Ft Lauderdale 561-2983Miami 264-2983GEORGIADataMart, Inc.3001 N. Fulton DriveAtlanta 233-0532

HAWAII

Real Share

190 S. King Street #890

Honolulu 536-1041

ILLINOISComputerland

Arlington Heights 255-6488Niles 967-1714Oaklawn 422-8080

Data Domain1612 E. Algonguin Rd.Shaumburg 397-8700Itty Bitty Machine Company1316 Chicago AvenueEvanston 328-6800Team ElectronicsCarpentersville 428-6474Decatur 877-2774Galesburg 344-1300Moline 797-8261Peoria 692-2720Rock Island 788-9595Rockford 399-2577Schaumburg 882-5864Springfield 525-8637INDIANAThe Data DomainFort Wayne 484-7611Bloomington 334-3607West Lafayette 743-3951Indianapolis 251-3139The Home Computer Center2115 E. 62nd St.Indianapolis 251-6800

IOWA

The Computer Store4128 Brady St.Davenport 386-3330Team ElectronicsAmes 232-7705Bettendorf 355-7013Cedar Rapids 393-8956Davenport 386-2588Dubuque 583-9195Iowa City 338-3681Sioux City 252-4507Sioux City 277-2019Waterloo 235-6507Video Midwest, Inc.2212 Ingersoll Ave.Des Moines 244-1447

KANSAS

Barney & Associates425 N, BroadwayPittsburg 231-1970Team ElectronicsGarden City 276-2911Hutchinson 662-0632Lawrence 841-3775Manhattan 539-4636Salina 827-9361Topeka 267-2200Wichita 685-8826Wichita 942-1415Wichita 682-7559KENTUCKYComputerland813 B. Lyndon LaneLouisville 425-8308The Data DomainLexington 233-3346Louisville 456-5242MARYLANDComputerland16065 Frederick RoadRockville 948-7676Computers, etc.13A Allegheny Ave.Towson 674-4742

MASSACHUSETTS

The Computer Store, Inc.120 Cambridge StreetBurlington 272-8770

MICHIGANTeam Electronics

Escanaba 786-3911Menominee 864-2213

MINNESOTATeam Electronics

Minnetonka 544-7412Edina 920-4817Eden Prairie 941-8901Bemidji 751-7880Willmar 235-2120St. Cloud 253-8326Owatonna 451-7248Hibbing 263-8200Virginia 741-5919St. Anthony 789-4368West St. Paul 451-1765Minneapolis 377-9840St. Paul 227-7223St. Cloud 251-1335Minneapolis 869-3288Minneapolis 378-1185Maplewood 777-3737Mankato 387-7937Eveleth 749-8140St. Paul 636-5147

MISSOURI

Electronic Components, Intl.1306-B South Hwy 63Columbia 443-5225Team ElectronicsBiscavne Mall301 Stadium Blvd.Columbia 445-4496

MONTANA

Computers Made Easy415 MorrowBozeman 586-3065Team ElectronicsGreat Falls 852-3281Missoula 549-4119NEBRASKATeam ElectronicsGrand Island 381-0559Lincoln 435-2959Omaha 397-1666Omaha 333-3100Norfolk 379-1161North Platte 534-4645NEW HAMPSHIREComputermart170 Main StreetNashua 883-2386

NEW JERSEY

Computerland

2 De Hart Street

Morristown 539-4077

Computermart

501 Route 27

Iselin 283-0600

NEW YORK

ComputerlandBuffalo 836-6511Ithaca 277-4888Computer Mart of NY.118 Madison Ave.New York 686-7923

Co-op Electronics9148 Main StreetClarence 634-2193

NORTH CAROLINA

Byte Shop

1213 Hillsborough St.Raleigh 833-0210Computer Room1729 Garden TerraceCharlotte 373-0875Rom's & Ram'sCrabtree Valley MallRaleigh 781-0003

NORTH DAKOTATeam Electronics

Bismarck 223-4546Fargo 282-4562Grand Forks 746-4474Minot 852-3281Williston 572-7631OHIO

Computerland1304 SOM Center Rd.Maylield Heights 461-1200The Data DomainDayton 223-2348Cincinnati 561-6733OKLAHOMABits, Bytes & Micros1186 N. MacArthurBlvd.Oklahoma City 947-5646High Technology1020 W. Wilshire Blvd.Oklahoma City 843-9667

Team Electronics

Norman 329-3456Oklahoma City 634-3357Oklahoma City 848-5573Stillwater 377-2050Tulsa 633-4575Tulsa 252-5751Yokon 373-1994OREGONTeam ElectronicsBend 389-8525Canby 266-2539Salem 364-3278PENNSYLVANIAComputer Mart of PARoute 202King of Prussia 265-2580

SOUTH DAKOTATeam Electronics

Pierre 224-1881Rapid City 343-8363Sioux Falls 336-3730Sioux Falls 339-1421Sioux Falls 339-2237Watertown 886-4725

TEXAS

Byte Shop3211 FondrenHouston 977-0664ComputerlandHouston 997-0909Austin 452-5701Computer Shops, Inc.13933 North CentralDallas 234-3412The Computer Shop6812 San PedroSan Antonio 828-0553

Computer Terminal2101 Myrtle St.El Paso 532-1777TheKA Computer Store1200 Majesty DriveDallas

VIRGINIA

The Comouter Hardware Store818 Franklin St.Alexandria 548-8085Home Computer CenterVirginia Beach 340-1977NewDort News 595-1955Timberville ElectronicsP.O. Box 202Timberville 896-8926

WASHINGTON

Team Electronics423 W. YakimaYakima 453-0313

WASHINGTON, D.C.

Gerogetown Computer Store3286 M. St. N.W.Washington, D.C. 362-2127

WISCONSINTeam Electronics

Eau Claire 834-0328Eau Claire 834-1288Madison 244-1339Milwaukee 461-7600Racine 554-8505Sheboygan 458-8791Greendale 421-4300Rhinelander 369-3900LaCrosse 788-2250Wausau 842-3364Milwaukee 672-7600Janesville 756-3150Manitowoc 684-3393Milwaukee 354-4880Oshkosh 233-7050WYOMINGTeam ElectronicsHilltop Shopping Center207 S. MontanaCasper 235-6691

CANADA

Future Byte

2274 Rockland

Montreal, Que, 731-4638

AUSTRALIA

Computerland52-58 Clarence St.Sydney, NSW 29-3-153

apple computer inc.

"^"^"^ 10260 Bandley Drive

Cupertino, California 95014(408)996-1010

SEE OUR PRODUCT AD ON PAGES 16 AND 17.EURAPPLE

European Operations of Apple Computer, Inc.2031 Byron StreetPalo Alto, CA 94301(415) 964-7020

Circle 5 on inquiry card.

BYTE March 1978

119

Photo 4: An illustration ofupper and lower case letterson the PET. 26 of the64 graphics characters canbe exchanged for lowercase letters by altering anaddress line on the char-acter generator read onlymemory.

Keyboard

A much criticized feature of the PET isthe design of the keyboard itself. It is acalculator style keyboard rather than a truetypewriter keyboard. The keys are smalland flat (about a half inch square and aquarter inch deep). They are tightly packednext to each other and are arranged in verti-cal rows rather than the slanting rows usedon a typewriter keyboard. Although thealphabet follows the usual typewriter layout,the PET keyboard really cannot be used fortouch typing because of the size, depth andspacing of the keys. The keyboard is saidto be reliable and long lasting, but I did findthat the space bar would not register correctlyunless it was pressed squarely in the middle.Certainly the keyboard lowers the cost ofthe unit somewhat, and Commodore pointsout that their keyboard provides a largernumber of keys and hence more graphiccharacters, but it is definitely more difficultto use. As a result many personal computerusers may try to interface a separate type-writer style ASCII keyboard to the PET.

A BASIC program can obtain input ofnumeric quantities and character strings fromthe keyboard using an INPUT statement.But Commodore BASIC also includes a GETstatement, which allows the program to cap-ture each key from the keyboard as it ispressed without the scanning, editing andconversion normally performed by theBASIC system on input. This feature makesit easy to implement interactive keyboardgames.

Cassette Drive

Also built into the PET's cabinet is anaudio cassette recorder, which can be usedfor saving and loading programs and data.This device is hand operated much like anordinary cassette recorder, but the motorcan be started and stopped under softwarecontrol, and the state of the manual switchescan be sensed to a limited extent by soft-ware (yet the PET will still try to save a pro-gram on cassette if you've pushed PLAYinstead of PLAY and RECORD). The cas-sette drive is said to be "modified byCommodore for much higher reliabilityof recording and record retention." Theexact recording method used by the PET isnot yet documented, but it appears tooperate at a speed in the range of 1000 to1400 bits per second. Because all informa-tion is recorded redundantly, the effectivedata transfer rate is about half this much.But the redundant recording enables thePET to detect and correct many recordingerrors. In my experience, data storage on thePET cassette drive has been remarkably re-liable and trouble free.

Operating System

An elegant cassette operating systemin the built-in read only memory supportsnamed tape files of both programs anddata, with file names up to 80 characterslong. A SAVE command writes a programonto a tape cassette, and the thoughtfullyprovided VERIFY command can thenbe used to reread the program from cas-

120

BYTE March 1978

More Than Just Hardware.

When you put the MSI 6800 ComputerSystem together with our FD-8 Floppy DiskMemory, you have the best 6800 hardwarepackage available today.

But to make a computer system work,you need more than just powerful hardware,you need powerful software . . . and MSI haswhat you need.

MSI Disk Extended BASIC Available inBoth Compiler and Interpreter Versions

The new Software Dynamics BASICCompiler is now available from MSI in an FD-8

rT7Tiir^iiu^»»yc77?*w^ir«]iBMn:ihi'sTWr»f?nlcot

business applications.

The Excellent TSC Editor In An FD-8Disk Version

TSC's new text editing system is clearlythe most powerful editor available for anymicrocomputer system. The FD-8 disk versionallows you to edit and assemble long sourcefiles from disk and to place object code on diskas well.

MSI Reverse Assembler

Our Reverse Assembler for the FD-8 allowsdisassembly of object code programs, completewith creation of symbol tables, labels, and equatestatements. The source code is placed on diskwhere it can be edited and reassembled.

Interpretive Debugger

An Interpretive Debugger is now availablefor MSI and SWTP 6800 systems. IDB is themost complete debugging package ever releasedfor 6800 systems.

Hardware and software . . . MSI offers a

new 1978 Catalog and get all the details about

il_ _ ___!____ _ _tl_ _ _ £• _ _ lfPI J a _

Liiese ami many tuner mie moi prouucLs.

THidevett Scientific*)HA&wmeHt4>

220 West Cedar

Olathe, Kansas 66061

(913) 764-3273

TWX 910 749 6403 (MSI OLAT)

TELEX 42525 (MSI A OLAT)

Circle 72 on inquiry card.

BYTE March 1978 121

Data Types:Arrays:

Precision:

Speed:

Statements'.

Operators:

Built-inFunctions:

OtherFeatures:

sette and compare it to the program stillin memory to verify that it was writtensuccessfully. This is an essential featurewhen dealing with audio cassettes, if onlyfor the user's peace of mind. A LOADcommand will search down the tape for anamed program and then load it intomemory. Similarly, a data file, written ontape from BASIC by means of OPEN,PRINT# and CLOSE statements, can besearched for and read by another BASICprogram using OPEN and INPUT#statements.

With a little care, programs can bechained together: a program segment inmemory can automatically load the nextprogram segment from cassette and con-tinue execution. I was able to do this byplacing LOAD and GOTO statements(separated by a colon) on the same BASICline; the old program segment seems to becompletely erased and replaced by thenewly loaded segment, but data values arepreserved.

The PET's built-in operating system is

Real numbers (eg: A), integers (A%) and strings (A$) of up to 73 characters.

Any number of arrays of reals, integers or strings with any number ofdimensions.

Ten significant digits for real numbers.

Executes the loop 10 FOR 1=1 TO 10000, 20 NEXT I in about 15 seconds.

LET

READ

DATA

RESTORE

PRINT

INPUT

GET

/t

ABSINTRNDSGN

SAVELOADVERIFY

GOTC

1

IF .. .

THEN

FOR .

. . TO . . .

STEP

NEXT

GOSUB

RETURN

ON . .

.GOTO

ON . .

.GOSUB

STOP

END

<>

>=

<=

>

<

SIN

FRE

COS

TAB

TAN

SPC

ATN

POS

LOG

Tl

EXP

OPENCLOSE

PRINT*INPUT*GET*

Tl$ST

DIMREMDEF FNRUNCO NTNEWLISTCLR

AND

OR

NOT

LEFT$

RIGHTS

MID$

CHRS

ASC

LEN

VAL

STR$

PEEK

POKE

USR

SYS

WAIT

CMD

Table 1: A brief summary of the features and performance of CommodoreBASIC. The BASIC interpreter was developed for Commodore by MicrosoftInc, Albuquerque NM, designers of the original AI fair BASIC. Accordingto Commodore's engineers, the PET's BASIC actually includes some addi-tional features not documented in the preliminary users' manual, from whichthis information was taken.

capable of handling multiple cassette drivesand apparently other peripheral devicesas well. A second cassette drive interfaceis in fact included in the basic PET.

Commodore BASIC

Table 1 summarizes the features of thepowerful BASIC interpreter built into thePET Commodore BASIC, developed by thefolks at Microsoft who brought you AltairBASIC, features real numbers, integersand strings, multidimensional arrays, a fullset of mathematical functions, and a varietyof extensions for string handling, input andoutput on external peripherals and machinelanguage access.

Commodore claims that the PET's BASICis at least 20 percent faster than othermicrocomputer BASICs, and the tests whichI have run support this claim. In addition,Commodore BASIC is efficient in its useof memory, for it encodes BASIC state-ments as they are entered so that keywordssuch as PRINT and INPUT occupy only onebyte. Another feature which can save timeand memory space, especially when largearrays are involved, is the use of integervariables (which occupy two bytes) in placeof real variables (which require five bytes).Programs are also stored on cassette inencoded form. This speeds up the processof saving and loading programs, but makesit more difficult (especially in the absenceof documentation) to enter BASIC programsfrom an external device such as an ASCIIkeyboard or a paper tape reader, or to writeprograms, such as macroprocessors, whichmust manipulate program text as data.

For readers unfamiliar with Altair BASIC,the PET's character string handling functionsare worth mentioning. LEFT$, RIGHT$ andMID$ are used to extract a substring ofspecified length and position from a charac-ter string. LEN returns the length of a string,and VAL and STR$ convert numeric quan-tities to character string form and vice versa.ASC obtains the internal character code fora given character, and CHR$ converts acharacter code into a single character stringfor handling as such in BASIC.

Machine Language Access

The PET user is not restricted to workingin BASIC, for the PET is designed to supportentry and debugging of machine languageprograms, and even other languages andprogramming environments. The BASIC usercan examine or modify any memory loca-tion with the PEEK and POKE statements,or call a machine language subroutine viathe USR function. Some nonstandard 10devices can be handled with the aid of the

122

BYTE March 1978

WAIT statement, which repetitively tests amemory location (such as a PIA port) untilspecified bits are set. Finally, the SYS com-mand can be used to transfer "completecontrol of the PET" to a machine languagesubsystem previously loaded into memory.According to Commodore's engineers,it is possible to save and load machine lan-guage programs on cassette, and undoubt-edly an assembler in read only memory willbe offered some time in the future. Amachine language monitor, similar to MOSTechnology's TIM, but utilizing the PET'skeyboard and video display, has beendeveloped for the PET. It was originallyintended to reside in the PET's read onlymemory, but was squeezed out by othersoftware and is now loadable from cassette,according to the latest word I've heard.As of this writing, Commodore has notreleased the machine language monitor oncassette, nor any documentation describingits capabilities.

Expansion

One of the nicest aspects of the PET'sdesign is the degree to which expansionprovisions have been built into the basicunit. The main printed circuit board is con-

nected by means of plugs to the keyboard,CRT and built-in cassette. It includes fouredge connectors which reach the outsideworld through openings at the base of thePET's cabinet. These edge connectorsprovide:

1.A second cassette drive interfacewith read, write, motor control andsense lines.

2. An 8 bit programmable 10 port,actually the unused portion of anMOS Technology MCS6522 VersatileInterface Adapter (VIA).

3. An instrument interface obeying thediscipline of the IEEE 488-1975standard.

4. The microprocessor's address, dataand control buses.

Provision for expansion is built into thePET's read only memory operating systemas well. The second cassette drive and theIEEE 488 instrument interface appear tobe fully supported by BASIC through theOPEN, CLOSE, PRINT*, INPUT#, GET#and CMD statements. Use of the VIA portand the address, data and control buses mayrequire some machine language program-ming, although much could be done withthe PEEK, POKE and WAIT statements

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BYTL March 1978

123

Photo 5: The PET props open for easy service access. Besides the mainprinted circuit board, the unit contains a TV chassis type circuit board and athird board in the cassette recorder.

in BASIC. Special programming could alsotake advantage of the VIA's peculiar serial10 capability. And theoretically, one couldunplug the built-in keyboard from themain printed circuit board and plug inanother keyboard and logic interface.Again, Commodore to date has not pro-vided documentation of any of the expan-sion options, and I have not been able totest these features. But I did see the PETdriving a programmable oscilloscope in ademonstration at a trade show last summer.For those interested, the IEEE 488 interfacestandard documentation can be obtainedfrom the IEEE Service Center, 445 HoesLn, Piscataway NJ 08854, (201) 981-0060.

Application Software

No application programs were suppliedwith the PET I received, not even a demon-stration cassette which I had requested.But many of the first PETs off the produc-tion line are being delivered to people whohave purchased one with the idea of develop-ing generally useful application programs.Commodore plans to reproduce and sellapplication programs through its dealers,offering royalties to the software developers.

And if the PET follows the pattern of otherpersonal computers, additional systems andapplication software are likely to be offeredby independents as well. Many applicationprograms in BASIC can be found in booksand in the files of large scale computersystems. Some of these programs are copy-righted and most will require some modifica-tion to fit the features of CommodoreBASIC, but far less effort should be requiredto adapt such existing programs than towrite the programs from scratch.

The PET has considerable potential inschools and universities, and it appears thatmany of the currently active software devel-opers are especially interested in educationalapplications. I would not be surprised tosee the PET show up in classrooms and uni-versity computer centers across the country,taking the load off game program burdenedtimesharing systems, and spurring newcourses and educational research projects.

Availability and Delivery

Initially Commodore followed a policyof "cash now, delivery later" which meant,in my case, delivery on October 11 1977 ofa PET which I paid for in late June. This wasnominally within Commodore's contractualobligation to deliver in 90 days. This situ-ation should change, however, as Commo-dore builds up its manufacturing volumeand works off the backlog of initial orders.As this is written, I have heard that a fewdealers have demonstration units on displayin their stores, and at least one dealer hasbegun accepting orders on credit cards.Someday you may be able to buy a PETat your local computer store and carry ithome, but until then you should probablybase your plans and expectations on "worstcase" estimates of delivery time.

Warranty and Service

Service has always been a problem inthe personal computer industry. It repre-sents an even bigger problem for Commo-dore, since the PET will be distributedthrough calculator dealers as well as com-puter stores, to ordinary consumers as wellas to computer hobbyists. Commodore'sapproach to the problem has been to designthe unit to be serviced as easily as possible.

The PET cabinet props open for easyaccess, as shown in photo 5. The entireunit contains only three individually re-placeable printed circuit boards. The mainboard can be snapped out and returnedto the factory or replaced by a Commodoredealer. A 1 K byte diagnostic routine is in-cluded in the PET's read only memory,

124

BYTE March 1978

Problems for Computer Solution by

Steve Rogowski, Teacher Edition. A collec-tion of mathematical problems designedto stimulate thought and encourage researchby students towards the goal of a finalsolution. The subjects range from arithmeticthrough calculus and on to problems thathave yet to be resolved. An analysis of eachproblem provides ideas on logical approa-ches to a solution, and a sample programdemonstrates one possible final solution.$9.95.

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Cauchon. People are always looking fordetails of applications for the computer. Itis one thing to say "gee whiz wouldn't it benice if. . ." but such thoughts are but thestimulus to action. One result of a "geewhiz" idea is a series of educational andtutorial BASIC programs for use by teachersof chemistry, invented by Paul A Cauchonand published by Educomp Corporation.This book contains a collection of tutorial,simulation and problem generation pro-grams which can be employed to advantageby teachers in high schools or collegeswherever a BASIC facility is available. Ifyou're a chemistry professor or teacher bytrade, or just a hobbyist interested inchemistry, this book will prove to be aninvaluable tutorial aid. S9.95.

Take a Byteof APL

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The Underground Buying Guide, by

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BYTE March 1978

125

Photo 6: The PET receivedby the author was de-livered with several faultymemory chips, which ledto a variety of strangeeffects in BASIC asillustrated by this photo.The statement numbered20464 was not typed bythe user, and the state-ment numbered 4120 waslisted twice by the LISTcommand. After the badmemory chips were re-placed, these symptomsdisappeared.

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so that with special test equipment thisboard is "self-diagnosing." The secondboard, for the CRT display, is virtuallyidentical to the same section of a chassis in aconventional TV set. The third board, forthe cassette drive, is similar to the circuitboard found in an ordinary audio cassetterecorder.

Commodore believes that the PET couldbe serviced by a TV repairman equippedwith a brief service manual. It is not yetclear, however, just how or whether TVrepairmen might be licensed to repair PETsunder warranty. Presumably experiencedcomputer hobbyists could read the servicemanual and diagnose problems with theirown PETs, requesting replacement partsfrom the factory, but how Commodoremight react to this possibility is an openquestion. Of course, there is always the pro-blem of latent bugs in the read only memorysoftware, which a TV repairman might havesome trouble diagnosing. Seriously, the onlyrealistic approach to handling softwareproblems is for hobbyists and PET dealers todocument carefully with examples anyanomalous behavior of their PETs, referringthe information back to the software deve-lopers.

At present, however, PETs are beingserviced only at Commodore's headquartersin Palo Alto CA. The user must arrange toship the unit to Palo Alto and must beprepared to wait up to eight weeks for thePET to be fixed.

126

BYTE March 1978

Circle 25 on inquiry card.

Photo 7: The CommodorePET 2001 is an eminentlyusable machine, as is illus-trated by this display of a6502 assembler written inthe machine's version ofthe BASIC language. Thisassembler was originallywritten in FORTRAN foruse on large systems, andimplementing it in BASICwas a relatively mechanicaljob of translating state-ments and typing theminto the PET.

Although eventually Commodore mayhave a nationwide service network for thePET, my informal service experience withthe early unit which I received has beenquite similar to that reported by owners ofother personal computers. I was unluckyenough to receive a unit with three badmemory chips which caused a variety ofstrange effects such as those illustrated inphoto 6. For several weeks after I receivedthe PET I was unable to get anyone atCommodore on the phone and was left tofend for myself. I suspected a memoryproblem, but my memory test programswritten in BASIC apparently were notexhaustive enough to locate the faults.Finally John Feagans, one of the designersof the PET, called me, quickly diagnosed theproblem and mailed me a machine languagememory diagnostic program and some re-placement memory chips. With these aids Iwas able to find and replace the defectivechips in a couple of hours.

Conclusion

The PET may well be an "appliance"computer, suitable for the most casualcomputer user or, with appropriate appli-cation software, for the average consumer.But it is also a powerful tool in the hands ofan experienced computer hobbyist. Theoptions and flexibility built into the PET,ranging from string handling and machinelanguage access to the second cassette inter-

face and the IEEE 488 bus, make it quitesuitable for expansion and enhancement. Asa small illustration, despite the problems Ihave had with my PET, I have been able todebug and put into use several thousandlines worth of BASIC programs. Amongthese is a 6502 assembler written in BASIC,a program of about 700 lines which Iorginally wrote in FORTRAN for use on anIBM 360 and a DECsystem 10.

For the casual user, the PET is a verylow cost computer which can be program-med easily in BASIC, for use in schools, forplaying games and for fairly complex calcu-lations in engineering, statistics and the like.A better keyboard, a disk and a reliableprinter would make it suitable for somebusiness applications. In fact, Commodore issaid to be considering development of a PETII computer which would incorporate severalof these features. Whether the PET evolvesinto a general-purpose computer witha variety of programming systems andperipherals will depend on Commodore'sfuture moves and on the activity of PETowners.

The PET is far from the only alternativein the marketplace today, but it is a strongcontender. If you are contemplating apurchase, you would do well to compare itsfeatures against other offerings, talk toowners of the PET and other computers, andthink about what you really want from apersonal computer. I hope that this reviewarticle will help you in your evaluation."

BYTE March 1978

127

Continued from page 14

In conclusion, I would like to saythat his last point, that his program islogically correct, is valid. Inasmuch asthe purpose of designing before program-ming is to produce a logically correctsolution to a problem, Mr Higgins hasdone well, but he should have stoppedthere. From there on, top-down struc-tured programming should have takenover.

Douglas Drury

31 Brookmount Rd

Toronto, Ontario

CANADA

A COMMENT ON C FORTHE DEC 10

In his article "C: A Language forMicroprocessors?" in October 1977BYTE, J Gregory Madden mentionsrumors about a C compiler for theDEC-10. I would like to direct hisattention to a technical report fromMIT. That report is MAC TR-149, "APortable Compiler for the Language C"by Alan Snyder, May 1975. The com-piler described in this report exists onthe PDP-10 and HIS-6000 compilers.

Paul Dietz

Dept of Computer Science

Cornell University

Ithaca NY 14850

WAIT AND C?

The article "C: A Language forMicroprocessors?" by J Gregory Madden(October 1977 BYTE, page 130) was inmost respects a well-written tutorialrevealing the overall flavor of the lan-guage. However, as one of the imple-mentors of a new C compiler for theDEC PDP-11, I would like to correctseveral important inaccuracies in thearticle.

Contrary to what is said on page 132,column 2, the method for changing thevalue of a variable in the calling functionis not an "explicit exception to the callby value rule," but rather employs apointer argument.

Structures may not appear as argu-ments or the returned value of a func-tion as claimed on page 136, column, 2;but pointers to structures may so appear.

In the structure declaration on page136, column 2, the initialization sectionshould appear after the structure-name,not before it.

This reader was also momentarilyconfused by the use of "equivalence"on page 134 to mean assignment of anew value to a variable (eg: x = x+1).

Mr Madden's astute judgment thatthe C language is appropriate for micro-processors will soon be vindicated. Weat Yourdon have just completed a Ccompiler and suitable documentationfor the DEC PDP-11 running underDEC'S RSX-11 operating system, and weanticipate offering an Intel 8080 versionin early 1978. It will soon be transplant-

ed to other DEC systems, includingRT-11 for LSl-lls. What should alsomake Mr Madden happy is that C com-pilers from Yourdon are implementedin the C language and produce optimizedsource code in assembler language forthe host machine!

Carroll Zahn

Senior Staff Consultant

Yourdon Inc

1133 Av of the Americas

New York NY 10036

ALARMING SYSTEMS?

In reply to M Barlow's letter inNovember 1977 BYTE, a UniversalAlarm Annunciator is available fromS & T Systems. The basic annunciatorsystem consists of a microprocessorbased controller with 96 optically iso-lated inputs. Alarm indications aredisplayed on a video monitor with asmany as 14 alarm indications displayedat any one time.

Options available include a dualdrive floppy disk for storing actionprocedures, a printer to produce a hardcopy record of activities, and a papertape reader for loading alarm messages.

The system with the disk option sellsfor less than $14,000. More informationcan be obtained from S & T Systems,1302 Fawn St, Tullahoma TN 37388.

]oe B Thompson

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COMMENTS ON APL AND OTHERTOPICS-FROM MALAYSIA

I am one of your new readers. Everytime I savour your many fine articles, Ihave only one regret, that I did notdiscover your magazine earlier.

I have been following the interest inAPL as evidenced by other readers'letters. Might I venture a few of myopinions on the matter?

As for the matter of binary repre-sentation, I believe that the ASCIIcode has one spare bit. This wouldallow up to 128 additional characters.(Or have they been assigned functionsI don't know of?) An extra "shift"key would control this eighth bitdirectly, allowing the use of existingkeyboard encoders. I think that usingthis bit for cursor indication on someterminals is sheer waste.

I may be wrong, but wouldn't an8 K EROM like the 2708 suffice todecode all characters unique to APLfor the video display? It could be con-figured as 64 by 16 by 8 (characterby row by column). I count 48 specialcharacters including overstrikes, withroom for more. Once a standard hasbeen established and demand rises, thena mask programmed version is not toofar off. This shouldn't set the hobbyistback more than $25, perhaps less, nowthat the nonerasable plastic versions arein the pipeline. I am neglecting "burn-

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BYTE March 1978

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BYTE March 1978 129

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Bit Pad is the newest product from Summagraphics, the leadingproducer of professional digitizers. 11 has a small 11-inch active area anda small $555 price tag. But the list of applications is as big as yourimagination.

Better than a joystick or keyboard for entering graphic information,it converts any point on a page, any vector, any distance into its digitalequivalents. It's also a menu for data entry. You assign a value, or aninstruction to any location on the pad. At the touch of a stylus, it'sentered into your system.

Who can use it7 Anyone from the educator and the engineer to thehobbyist and the computer games enthusiast. The data structure isbyte oriented for easy compatibility with small computers, so you canadd a power supply stand-alone display cross-hair cursor and manyother options.

$1,000.00 creativity prize. You can also add $1,000.00 to yourbank account as a reward for your inventiveness. Just write an articleon an original Bit Pad application and submit it to any nationalsmall-computer periodical. I f the editors publish it - and the decisionis solely theirs -Summagraphics will pay you $1,000.00. ContactSummagraphics for rules concerning this offer.

lAummadiaphicd

** ' corporation

35 Brentwood Ave., Box 781, Fairfield, CT 06430Phone(203) 384-1344. TELEX 96-4348

ing" the PROM which is the labour oflove anyway.

But whatever the final concensus,please let us have uniformity for thecommon good. Each setting up his or herown standard would only hinder theadvancement of this lovely languageon micros, not to mention problemsof information interchange, etc.

I must confess that I am not praisingAPL from experience; I have access onlyto FORTRAN and BASIC. But fromwhat I have learnt of it, I can't wait toget my hands on an APL terminal.Hassling with array manipulation inFORTRAN is really frustrating.

Keep up the good work!

Philip Yap Sue-Ken

4 Pesiaran Syed Putra

Kuala Lumpur 08-06 W MALAYSIA

MATHEMATICS SURVEYBY A READER

In the personal computer magazinesI have read, I have not seen any refer-ence to the practical role of mathematicsin computing. Since I have had eightyears experience in teaching collegemathematics, and held an advanced de-gree in that subject, I find myself curiousabout this aspect. To do really well, doyou need to know any more than how topunch the buttons on a cheap handcalculator?

This is not a question about whatyou need to get started: obviously allyou need to get started is patience (lotsof it), hard work and a willingness tolearn. But does mathematics have a placein the growth and development of thehobbyist, and if so, how much of whatkind? Are there specific situations wheremath was or would have been a big help?I am not limiting things to subjects ofthe traditional curriculum, but includethings like binary arithmetic, Booleanalgebra, model theory, statistics, etc.

In short, I am attempting to find outwhat hobbyists are doing (or not doing)with mathematics. I am preparing aquestionnaire, which not only has a fewquestions but leaves a generous amountof space for comment on what is, whatought to be, or even on how stupid it isto fill out a questionnaire! I welcomeany kind of response, including insults,so long as they are in good taste.

Bennett Sawey

318 N Maple St #16

Truth or Consequences NM 87901

/ would wager that you will findmathematical concepts high on the listof "practical theory" embraced by manyusers of personal computers. . .CH

A COMMENT. . .

On page 174 of October 1977 BYTE,you pose the problem of determiningwhether two numbers A and B are nearlyequal, to within some small rangeDELTA. You further specify that the

130

BYTE March 1978

Circle 117 on inquiry card.

language in use has no absolute function,and then offer the horrendous solution:

IF ( (A-B)<0

and (A-B)>DELTA)or ( (A-B)>0

and(A-B)<DELTA)THEN

A much simpler solution is:

IF (A-B)<DELTA

and (B-A)<DELTATHEN

or the equivalent:

IF B>(A-DELTA)

and B<(A+DELTA)THEN

However, even shorter is:

IF (A-B)t2<DELTA2THEN

where DELTA2 is DELTA squared.

Incidentally, in floating point sys-tems you never need an absolute valuefunction if you have a square rootfunction, since SQRT(A*A) will obtainABS(A). The ABS function is a con-venience, and in some systems may beless susceptible to roundoff.

H Bradford Thompson

Dept of Chemistry

The University of Toledo

Toledo OH 43606

But is your proposal any less a kluge?Extracting a square root — even with thebest algorithm - has got to be a muchmore obscure calculation than the directone given.

KOMPUUTAR UPDATESFROM DAVID BRADER

I have received questions from BYTEreaders regarding my November 1977article on "Kompuutar." Some of thequestions are general enough to have apublished reply for those who thoughtabout writing but as yet have not.

About the 8 K byte dynamicmemory. . . .The design is complete, butduring debug I found that the $1 bargainchips I bought were not all functional.The board requires 16 IMS4060 orsimiliar chips, but only two have workedso far. Until I can afford to purchase 16new (rather than used) memory chips,the project is halted. The design appearsto function as intended but I will notpublish or give out information until it iscompletely tested. I can say this much:

1. It is an 8 K dynamic memorysystem that is self-contained onone 4.5 by 6.5 inch (11.4 by 16.5cm) vector card.

2. It refreshes itself invisibly to therest of Kompuutar.

3. It uses +5 VDC, +12 VDC, and-5 VDC.

4. It uses 4 l< by one 22 pin TMS-4060 memories or similiar.

5. The cost (wire wrap model) with

new chips is $180.

I have been asked about printed cir-cuits for Kompuutar. I did a cost anal-ysis of the system as designed (roughly$750 with 8 K of memory and a surplusmultivoltage power supply), and thena time estimate for the printed circuitartwork. The results caused me to decideagainst putting out the effort for Kom-puutar in its present form. I am con-sidering some modifications to thedesign which will be upward compatible.

If these work out over the next fewmonths, I will reconsider committingKompuutar to printed circuit boards.

Readers have frequently asked aboutsoftware. The TIM chip has many sub-routines which can be tapped if you arecoding in assembly language. A 2.2 Kbyte Tiny BASIC is available fromMicrocomputer Associates in Santa ClaraCA. Other software is advertised inpublications such as BYTE.

Talking about TIM, people askedwhat will interface to it. Any ASCIIserial input, ASCII serial output, orASCII parallel input devices, such as:a Teletype ASR-33, HP 2644A terminal,

We've gathered the family to show you why

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It took more than guts and a little luck toforge a position of leadership. We'renumber 1 because you get more whenyou buy PERCOM™. The reason, simply,is experience. Every product describedin this ad is based on nearly 10 years ofcrucial involvement in the design andmanufacture of computer peripheralsthat use cassettes for mass storage.

Experience. It's why we developed amore reliable data cassette for homecomputing. Why our interfacing unitsprovide both cassette and data terminalinterfacing. Why you get the fastest,most reliable cassette data rates fromPERCOM™. Experience. It's f/ie reasonfor PERCOM™.

For your SS-50 bus computer — (heCIS-30 +

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■ 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.)

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Prices include a comprehensive instructionmanual. Also available: Test Cassette, Re-mote Control Kit (tor program control ofrecorders). IC Socket Kit, MITS 680b moddocumentation. Universal Adaptor Kit(converts CIS-30+ for use with any COm-PUterl MIKBUG® Motorola, Inc.

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• Both cassette and data terminal inter-facing on one S-100 bus PC board.

• Interlaces 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, S99.95; 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.

PERCOM™ 'peripherals for personal computing'

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■ Foam pad spring is energy absorbing.Superior to leaf spring mounted padwhich tends to oscillate and cause flut-ter.

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PERCOM1" products may be purchasedfrom home computer dealers nation-wide, or may be ordered direct from thefactory.*

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PERCOM DATA COMPANY, INC.

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Phone:(214)276-1968

Circle 91 on inquiry card.

BYTE March 1978

131

Circle 10 on inquiry card.

PCC'S

Reference Book

of Personal

and Home Computing

Ever try to find the addresses of some manufacturers of, say,tape cassette or floppy disk interfaces for micros? Frustrat-ing, isn't it? Well PCC has done something about it. Thisbook lists hundreds of companies and stores selling hardware,software, and services. Survey articles on software, hardware,kits, applications and the future for the experienced and thenot-so-experienced user of micros. Also included in this edi-tion are bibliographies for further reference, book reviews,and an index of the articles from the major hobbyist maga-zines. All for the low price of $5.95, plus 50 cents postage.

Available through:

BITS, Inc.70 Main StreetPeterborough l\IH 03458

Master Charge andBankAmericard Welcome.

In unusual cases, processing may exceed 30 days.

A Collection of Programming Problems and Techniques, by H A

Maurer & M R Williams. Here's a book that presents you with pro-blems! Nearly 400 of them, in fact: problems in games like chess,bridge, and NIM; practical problems such as applications of the lawof sines, Cramer's rule for solving simultaneous equations, andapplications of Latin squares to problems in probability; and moreadvanced computer science topics such as the use of Backus-Naurform. One quarter of the book is devoted to an appendix that givesstymied readers hints on how to proceed with solutions to the pro-blems. The most valuable feature of the book, though, is its carefuland thorough explanation of the use of algorithms to solve pro-blems. No dyed-in-the-wool programmer or experimenter will beable to read this book for very long before trying to solve thetantalizing and well-presented problems. $13.95, plus 50 centspostage.

BITS Inc70 Main StPeterborough IMH 03458

Use coupon on page 147, writingin this books name.

a homebrew television keyboard ter-minal, high speed paper tape reader,etc, etc. . . .

Having worked in the digital elec-tronics area for several years, I took itfor granted that anyone could get theparts that I could. I goofed! I havegotten letters requesting names ofsources for some of the parts used inKompuutar. This has caused two thingsto happen. One, I have tried to find asource for the "special" parts required.Two, I have tried to substitute moreavailable parts in the design.

Two substitutions were decided on.The HP hexadecimal LED displays(HP 5082-7340) are replaced with TlL311 hexadecimal LED displays whichare available and cost less. The Intel3624-4 PROM is replaced by the Intel2704 EROM. This second substitutionimpacts the power supply requirementsand backplane wiring. With these twosubstitutions, I found that Jade Com-pany of Lawndale CA (see advertisementin November 1977 BYTE, page 243) cansupply all the ICs required, plus programthe Intel 2704. I am sure other com-panies can also supply these items andrecommend shopping around for thebest prices.

The changes to the backplane andmodifications to wiring, due to thesubstitutions, are available. For theseand a helpful hints package, send $2to the address below, to cover the costof Xerox and mailing.

David Brader

Kompuutar Works Ink

POB 483

Electric City WA 99123

ON COMPUTERS AND DNA

Have you ever seen a computer re-produce itself? Well, neither have I, andthat is the crucial difference betweenmisapplication of computer technologyand recombinant DNA research. If acomputer gets out of the laboratory, itjust sits there. If an organism gets outof the laboratory, it might just decideto have progeny, and if those progenyare pathogenic and can thrive, we'rein trouble, big trouble. That's whereinlies the challenge of recombinant DNA.It's the only science that can implementitself without intervention of engineer-ing. Think on that. That's where thethreat is.

I'm writing in response, of course,to the letter by Mark Bizer in theDecember 1977 BYTE.

B J Luberoff PhD

Editor, Chemtech

The American Chemical Society

48 Maple St

Summit NJ 07901

Now That You Bring Up the Subject:

Politically, banning research in agiven area will only drive the search fortruth underground, witness a long seriesof historical martyrs to the under-

132

BYTE March 1978

Circle 10 on inquiry card.

standing of Nature starting with thePrometheus legend. The real dangers areunknown, in the same way that thedangers of atomic energy were unknownsome 50 years or more in the past. Butthe potential benefits of genetic en-gineering make the risk we'll worth thechallenge. . .CH

RAMBLING RUMORS ABOUT Tl

Recently, in San Diego CA, by one ofthose rare coincidences, I happened tofall into conversation with a person whointroduced himself as a member of TexasInstruments' design section for pocketcalculators. He has read BYTE from dayone and was familiar with all Tl matterstherein, including my letter about theSR-51 working on the PC-1 OOA printer.

It was a mellow evening and a pity Idid not have a tape recorder and was notmore alert in my questions to him. Asfor the SR-51 on the printer, some workand some do not. He said the SR-51 Awas primarily a repackaged SR-51 forcosmetic reasons. The printer itself hasvery little intelligence except for a char-acter generator. The decision of what toprint and where is a function of the cal-culator that is mounted on the printer.

As many of us know, the printer hasvery few moving parts: essentially astepper motor that advances the rubberdrive wheel for paper movement. Theprinter mechanism can be thought of asa single horizontal row of dots, althoughthe row is actually staggered to aid inheat dissipation. Internal timing in thePC-1 OOA compensates for the staggereddot positions. The stepper steps severaltimes in order to work through one printline.

Q: Can the PC-IOOA be made into aportable printer to work off batteriesaway from a power socket?A: Not likely because of the high currentpulses required for its operation. Thepaper used in the PC-1 OOA was purpose-ly chosen to be insensitive for greaterpermanence. Note the cautions con-cerning sunlight and fluorescent lightfor some papers. Since the paper isinsensitive, much greater heat is re-quired. An incidental feature of the highheat is that the print head tends to stayclean when compared with other papers.

The answer to many of my questionswas, "Tl is a very aggressive companywith the desire to make lots of moneyby filling the needs of the marketplace.When the bonafide need for a new pro-duct arises, if it is in Tl's area of exper-tise, Tl will be there, front and center,"for example:

Q: What will Tl do to enter the personal

computer area?

A: It is a very aggressive company. . . .

One interesting tidbit from our longdiscussion is the fact that Tl has used thesame chip set in most of their recentpocket calculators of every sort. The

processor in their new TI-59 is the sameas was used in the old SR-50, and eventhe SR-50 was not the first use. Thefirmware and the firmware chips havevaried greatly, and it is basically thefirmware that determines overt func-tions and operations. When I askedwhy the TI-59 cannot compute a fac-torial, he said, "Oh, it can computea factorial, but we needed the buttonfor something else. The factorial is inthe ROM of the chip, but you can'tget at it."

Q: Will there be hidden gold on the

TI-59?

A: Probably not. We worked our butts

off to insure that all features are overt

and well-documented. The TI-59 offers

much more than the SR-52, hidden gold

and all.

Q: Could you have given the T/-57 morethan a mere 50 program steps?A: Easily, but once again that was amarketing decision. More than 50 wouldhave helped to compete, but it would

Can you tell ourpreviously-ownedExecuport 300'$

from our new ones?

(No fair,peeking at the price.)

Now you can buy a great refurbished Execuport 300 portable ter-minal, at a fraction of the price of a new one.

These units have been rebuilt to "like-new" standards; are coveredby our standard one-year warranty, and offer the same, solid, de-pendable performance you expect from an Execuport 300, but may-be couldn't afford before.

For more information call Charles Kaplan, Computer TransceiverSystems Inc., East 66 Midland Avenue, Paramus, NJ ^tPKFII07652.(201)261-6800. " I1 SHI

Only $1795. (You peeked!)

Circle 32 on inquiry card.

BYTE March 1978

133

have then also impacted the TI-58 andother Tl calculators. In the total picture,including future pricing strategy, 50 pro-gram steps seemed right. The TI-5 7 ispriced such that students can buy acalculator good enough for engineering

use. The TI-57 does not suffer in com-parisons until it is compared with cal-culators costing much more.

Q: Can you confirm the rumor that thecalculator division of Tl will eventually

IT TALKS777e following unusual note appeared in our "in" basket on a "birth announcement'style greeting card.

fSFTETR. \0 morJTHSOF HARD lASoRj X /AM

Pleased td apmoo/ocje

THE 6>BTH OP A BoOroCJuk

^A<cW £=goo; Kmakf

CAMC AtivlE (?)TDOrV7#.r/W TERMINAL HAD M/4NY

PeTecTS A^o wasAlmost asocteX) —BcT M^s — W\TH -theMiKAc4.es of ncxje^/0

TECMMOUO&Y -THe•SASY TALKS A^O

iSlbs:'io"oz.

WEIGHT [_-—--_>

B0RN T0 Fr<rA^i<T>i<S.e^oyA

Best Re&a^DSj KorpOP THE Puof u30<?\<.

d7u«JiDt'fe>^

HOBBYISTS! ENGINEERS! TECHNICIANS! STUDENTS!

Write and run machine language programs at home, display video graphicson your TV set and design microprocessor circuits — the very first night- even if you've never used a computer before!

RCA COSMAC microprocessor/mini-computer

SPECIFICATIONS

ELF II features an RCA COSMACCOS/MOS 8-bit microprocessor ad-dressable to 64k bytes with DMA, in-terrupt, 16 registers, ALU, 256 byteRAM, full hex keyboard, two digit hexoutput display, 5 slot plug-in expansionbus, stable crystal clock for timing pur-poses and a double-sided plated-throughPC board plus RCA 1861 video IC todisplay any segment of memory on avideo monitor or TV screen.

Use ELF II to ... PLAY GAMES usingyour TV for a video display ...CREATEGRAPHICS pictures, alphanumer-ics, animated effects ... learn how toDESIGN CIRCUITS using amicroprocessor ... the possibilitiesare infinite!

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ELF II explodes into a giant when youplug the GIANT BOARD"1 into ELF'sexpansion bus. This powerful board in-cludes cassette I/O, RS 232-C/TTY, 8-bit P I/O and system monitor/editor...meaning your ELF II is now theheart of a full-size system with unlimitedcomputing power! S39.95 kit. $2 p&h.

• 4k Static RAM addressable to any 4kpage to 64k. $89.95 kit. $3 p&h.

• Prototype (Kluge) Board accepts up to32 I.C.'s of various si7.es. $17.00 kit. 51p&h.

• Expansion Power Supply. $34.95 kit.S2 p&h.

• Gold plated 86-pin connector. $5.70postpaid.

Coming Soon! wwvwsa'wv

Tiny Basic

ASCII KEYBOARD • CONTROLLERBOARD • D-A, A-D CONVERTER •CABINET

3.13 Litchfield Road, New Milford.Yes! / want to ran programs athome and have enclosed:D $99.95 plus $3 p&h for RCACOSMAC ELF II kit. Featuredin POPULAR ELECTROMCS.Includes all components pluseverything you need to writeand run machine language pro-grams plus the new Pixie chipthat lets you display videographics on your TV screen. De-signed to give engineers practicein computer programming andmicroprocessor circuit design,ELF II is also perfect for collegeand college-bound students (whomust understand computers forany engineering, scientific orbusiness career). Easy instruc-tions get you started right away,even if you've never used a com-puter before!

As your need for computingpower grows, five card expan-sion bus Cless connectors) allowsmemory expansion, program de-bugger/monitor, cassette I/O, Ato D and D to A converters.ASCII keyboard inputs.

CT 06776 Phone (203) 354-9375controllers, etc. (soon to beavailable as kits). Manual in-cludes instructions for assembly,testing, programming, videographics and games plus howyou can gel ELF II User's Clubbulletins. Kit can be assembledin a single evening and you'llstill have time to run programs,including games, video graphics,controllers, etc., before going tobed! □ $4.95 for 1.5 amp 6.3VAC power supply, required forELF II kit. □ $5.00 for RCA1H02 User's Manual.G I want mine wired and testedwith the power transformer andRCA 1802 User's Manual for$149.95 plus $3 p&h.Conn. res. add sales tax.

NAM E

ADDRESS

CITY

STATE_

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□ Send info on other kits!

PROM, ASCII keyboard inputs. Dealer Inquiries Invited

be as large as all other Tl divisions put

together?

A: Tl is a very aggressive company. . . .

Q: Shall we have another round of

drinks?

A: You arc in very aggressive company

YES.

San Diego is seldom foggy, but it gotfoggy that night.

Webb Simmons

1559 Alcala PI

San Diego CA 92111

ON SOFTWARE PROTECTION

Mr Mirsich, in his "Opinion on Soft-ware and Patentability, 1977," Novem-ber 1977 BYTE, page 162, is short-sighted in placing reliance on the law oftrade secrets to protect "software"inventions.

The major use of microprocessorswill be not in personal computers, butrather as logic replacements. Trade secretlaw will generally offer no protectionagainst legitimate reverse engineering.

Consider, for example, a washingmachine which, as a result of a new andnonobvious cycle sequence, provides animprovement over the prior art. Insteadof implementing the new control withconventional logic, a microprocessormay be used instead. There is absolutelyno reason why the new method of wash-ing clothes, ie: the new machine cyclesequence, cannot or should not be pro-tected by a patent. On the other hand,there is no way to "hide" the inventiononce it is embodied in the machine,and thus the law of trade secrets offersno hope for protection.

As for "software packages" sold inthe form of tape cassettes, for example,it is true that patent protection isprobably not available. But the law oftrade secrets will be of equally littleuse. It is copyright protection whichwill probably be the best approach insuch cases.

Michael I Rackman

Gottlieb, Rackman & Reisman

260 Madison Av

New York NY 10016

At BYTE, we put all our softwareeggs in the copyright basket.

AUDIO CASSETTE COURSESWANTED

Should you know of any institutionor company offering microcomputer/microprocessor instruction on audiocassettes, please let us know.

Richard A Polacsek, MD

Director, Welch Medical Library

Johns Hopkins University

1900 E Monument St

Baltimore MD 21205

Can any readers supply this infor-mation?'

134

BYTE March 1978

Circle 82 on inquiry card.

Let's Get Personalin Anaheim

June 6-8,1978

A rewarding personal experience is in store for youJune 6-8 at the NCC 78 Personal Computing Festival...the most comprehensive personal computingevent everheld. The Festival, a separate feature of the NationalComputer Conference, will include approximately 30program sessions, commercial exhibits of consumercomputing products and services, plus a contest andexhibit of microprocessor systems and applications. AllFestival activities will take place in the Disneyland HotelComplex, just a few minutes from the Anaheim Con-vention Center, site of this year's NCC.

Plan now to attend the big, new NCC 78 PersonalComputing Festival. The program will include specialpaper, panel, and tutorial sessions on such topics asspeech synthesis and recognition, computerized musicsystems, hardware and software design, computergraphics, and small business systems. All papers will bepublished in a softbound volume, Festival Digest 78,which will be available during NCC.

Festival exhibits will provide an extensive display ofcommercial offerings by organizations serving the per-sonal computing field. More than 100 companies, occu-pying over 175 booths, will display systems, compo-nents, terminals, software, kits,disc and tape cassettes,relevant publications, and related hobby items.

Rounding out the Festival will be a contest featuringmicroprocessor systems, devices, and applicationsranging from home-brew DOS and graphics terminalsto educational applications and computer games. Prizeswill be awarded for thebest exhibits.

Don't miss the year's most exciting personal comput-ing event. For more information, return the coupon orcall AFIPS at 201/391-9810.

□ Please keep me up-to-date on Festival plans andactivities.

□ My company is interested in exhibiting at the Festival.

□ Please send me information on the special NCCTravel Service.

Name

CompanyStreet

Division.

.State.

.Zip.

NCC 78Personal ComputingFestival

c/o AFIPS, 210 Summit AvenueMontvale, N.J. 07645telephone: 201/391-9810

Circle 81 on inquiry card.

BYTE March 1978 135

Circle 35 on inquiry card.

21 START-AT-HOMECOMPUTER BUSINESSES

in the shoestring, start-at-home

computer business handbook

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Plus - - hundreds of ideas onmoonlighting, going full-time,image building, revenue buildingbidding, contracts, marketing,professionalism, and much more.No career planning tool like itever published. Order now and ifyou're not completely satisfied,send it back within 30 days fora full and immediate refund.

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(801) 364-2411

Continued from page 6

The urge to solve the problem of auto-mated editing tools with a small system hasbeen growing within me for some time. Priorto starting this publication, I had often usedthe text editor of IBM's TSO software inpreparation and testing of programs and jobcontrol in a large system timesharing en-vironment. Earlier I had some experiencewith a more sophisticated editor, TECO on aDEC PDP-6. As a result of this experience,I dreamed of the possibility of a multiplewindow display, upper and lower casegraphics, and lots of characters. Since then,as I found myself getting into word pushingwith a vengeance as a daily way of life, theneed for a practical approach to automatedediting of manuscripts has become moreimportant. I have seen examples of what afast computer and good software can do indemonstrations of some automated editingtools used with PDP-10 hardware at Stan-ford Research Institute (now known as SRIInternational). Recently I have seen similarexamples at Massachusetts Institute ofTechnology's Artificial Intelligence Labor-atory. Ah, the frustration mounts! Whenwould I find the time or money to duplicatesuch tools?

In many respects, I feel like the prover-bial "shoemaker's child," running around"barefoot" with respect to the very tech-nology about which I am most concerned.To be sure, I am a little hypocritical when Imake this comment, for I do have a quitecomplete experimental laboratory in mybasement: it currently has a loose federationof four different microcomputer systemstalking to each other with programmed IOthrough parallel ports, each system special-izing in a particular phase of the musiccontrol problems I spend my spare timeupon. But this homebrew system is not aproduction tool for daily use in the office.Its status is anything but frozen, and as Iexperiment with the system it begins toresemble a bar of butter on a hot summerday. I am loath to use it as a productiontool, for its very charter as a test bed forexperiments is inconsistent with using itfor regular work. Our present conceptof automation in the editorial office hasconsisted of an IBM Correcting Selectric IItypewriter on each editor's desk, thebest electromechanical system, but farshort of a computer text editing system.

Knowing full well that my personalhomebrew system had limitations, I starteda process of defining the requirements of aproduction text editing system which wouldfit my needs at the office and would beconsistent with a "low" price tag using pro-

136

BYTE March 1978

Circle 76 on inquiry card.

ducts drawn from the small systems field.It is in this activity of defining an editingsystem with as much standard hardware andsoftware as I could get, that I found myselfexamining that class of complete systemscharacterized by extensive system software,extensive memory, video displays and massstorage on floppy disks. The activity ofspecifying such an editing system is the ex-tent to which I have carried the search as ofthis writing in early December 1977. During1978 I hope to see a practical fulfillmentof this concept in one system. The resultwill not come up to the level of what I haveseen at SRI in the way of high resolutiondisplays and interactive text manipulationconcepts, but I expect to get a workableand .useful approximation at a price whichI can afford. The requirements of theminimum system which will meet presentgoals are fairly simple to state:

• The editing software must have asophisticated programmable natureallowing definition and execution ofmacrooperations (with multiple levels ofconditional execution).

• The editing hardware and softwaremust support upper and lower case videodisplays with enough capacity to allowmultiple simultaneous "windows" ofinformation about the article file beingedited. Initially, a command languageoriented to an ASCII keyboard willsuffice for interaction.

• The editing system must supportsoftware of a good floppy disk oper-ating system with all the usual utilities,a macroassembler and one or morecompilers.

• The editing system must read, convert,edit, reconvert and write IBM compatibleEBCDIC text files on floppy disk media.

These requirements are based upon what Ithink I can get within the constraints ofprice (under $8000 to $10000 per system)and little or no software development orengineering design time on the part of my-self and my associates at BYTE. Let'sexplore some of the reasons why these fea-tures might be important.

Programmable Editing. ..

As a individual thoroughly schooled inthe uses and abuses of algorithms, one ofmy dearest wishes is to be able to specifyprocedures for the alteration of manuscripttext, rather than mere "find" or "find andreplace" or "delete" as found in most crudecharacter oriented text editor programs.

IDS

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88-MODEM: A complete serial I/O port and an Originate/Answer MODEM on anSt 00 bus compatible board. The 88-MODEM features automatic auto-dialer (notsoftware timed), operates at any software selected baud rate between 66 and 600baud, has separate 8-pole transmit and receive active fitters, and all functions aresoftware selected The 88-MODEM provides communication to -58 dbm and is intendedfor use with either a CBS (1001D) or CBT Data Access Arrangement for connectionto the telephone system. The kit price is $245.00.

88-UFC UNIVERSAL FREQUENCY COUNTER: The 88-UFC is an S100 compatiblefrequency and period measurement module. The 88-UFC has four software selectedinputs. Frequency measurement to above 600MHz and period measurement to 1 /10thmicrosecond are standard The counter provides nine digits of readout and is pricedat $179.00 in kit form.

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Circle 58 on inquiry card.

BYTE March 1978

137

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BYTl. is continually seeking qualitymanuscripts written by individuals whoare applying personal computer systems,designing such systems, or who haveknowledge which will prove useful toour readers. For a more formal descrip-tion of procedures and requirements,potential authors should send u self-addressed, stamped envelope to BYTEAuthors' Guide, 70 Main St, Peter-borough NH 03458.

Articles which are accepted arepurchased with a rale ot up to $50 permagazine page, based on technicalquality and suitability for BYTE'sreadership. Each month, the authorsof the two leading articles in the readerpoll (BYTE's Ongoing Monitor Box or"BOMB "J are presented with bonuschecks of tWO and $50. Unsolicitedmaterials should be accompanied by fullname and address, as well as returnpostage. ■

<inch-expression><jnch-units>

<jnch-cm-expression><metric-inches^>

As noted earlier, I was spoiled at one time inmy life when I had about six months ex-posure to Digital Equipment Corporation'sTECO text editor on a PDP-6 at the Uni-versity of Rochester, Rochester NY. Thattaste was enough to convey the power of aneditor in which I could compose conditionaltext alteration procedures, and execute themin real time to edit my files. (The files I wasediting were a number of FORTRAN pro-grams for )ohn Conway's game of Life,implemented at the expense of my gradesas a physics graduate student.)

For those unfamiliar with TECO, which isstill used in a number of forms on DigitalEquipment Corporation's computers, all Ican say is that it is addictive. I had no suchfeelings for the IBM TSO editor which I usedlater in my experiences, or for the quicklyimplemented and quite crude text editorI have since written for my homebrewsystem. The TECO l used six years ago hasprobably evolved considerably since I usedit, but that one taste was enough to leave mein love with the method.

The idea of programmable characteroriented text editing language is simple: theability to program use of primitives forscanning text in search of matches to asyntax pattern, and conditionally modifythe text based on local context. A classicexample with which I deal all the time ata manual level is the case of a decimalnumber followed by zero or "n" blanks,then a double quote mark ("), or one ormore variations of the abbreviations, and fullspellings of the singular or plural form ofthe English language word "inch." InBackus-Naur form, this syntax might benoted:

<number> <blanks> <jnch-units>

inchesI in

inch

The object of the macro to be composed forthis case is recognition of this syntax orapproximations of it, and replacing eachinstance with a standard representation ofthe measurement which includes metricequivalents calculated from the originalEnglish measurement. Ignoring the semanticsof the transformation, the resulting syntaxshould be:

<number> <blank> <inch-units> <jmetric-inches>( <CnurnbeL> cm )

This "inches to centimeters" transformation

138 BYTE March 1978

is the prototype of a number of similaroperations which convert any one of theusual English system units to metric withintext. At present I do this manually with apocket calculator featuring metric conver-sions, and a blue pencil for recording theresults. With some ingenuity, a text editorof the sort 1 am looking for can probablyhandle most such conversions semiauto-matically with interactive approval of theresults during execution of the macro.

As frosting on the whole macro textediting capability, it would be most usefulto record a library of symbolically refer-enced procedures such as "inches to centi-meters" as they are developed, so that theycan be called as needed through a simplesequence in the text editing commandlanguage. This may not be achievablethrough standard software which is usedhonoring the principle of "no softwaredevelopment" on my part.

Capacious Upper and LowerCase Displays. ..

An editing system for manuscript ma-terials without upper and lower case faci-lities is a contradiction in terms as far asI am concerned. One can certainly put upwith upper case only text editing hardwarein the context of any one of a number ofexisting high level languages and assemblers.But this absence of upper and lower casecapabilities in such systems' software andhardware is an archiac carry-over from theearlier days of data processing and com-puting, when keypunches and Teletypesdominated the technology. The job of

manuscript editing is impossible withouta full upper and lower case capability. Injudging articles for the magazine, I oftenwill not accept a manuscript from anauthor which is typed upper case only,unless one or more exceptional conditionsexist.

The use of video displays rather than hardcopy is also crucial. I have no intention ofwaiting for a slow mechanism and creatingmounds of waste paper as a result of theediting process. To be sure, hard copy willbe used, but only in the form of a confir-mation printout of the original state of thefile supplied after the act of keying a manu-script to disk, and possibly as a final reviewof the results of the technical editing. Anelectronic display is essential to allow quick-ly scanning and examining details of textwithout the speed limitations of mechanicaldisplays. The displays must be capaciousalso, since a mere 12 lines by 80 characters,or 16 lines by 80 characters, does not givea big enough field.

The ideal goal, which I have seen in thesystems at the artificial intelligence labora-tories mentioned earlier, is at least one fullpage of text, where a "full page" meansperhaps 50 to 60 lines of text. This is therough equivalent of the capacity of a page ofsingle spaced typewritten copy. This capa-city is then allocated to multiple logicalwindows on the data using the sytems soft-ware of the text editor. Such a display doesnot exist in any inexpensive practical formfor the small system field, although it can ofcourse be simulated. There are several Altair(S-100) bus products on the market whichput up 24 or 25 line displays of 80 char-

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BYTE March 1978

139

acters; so if I purchase two such boards andtwo video monitors side by side vertically(or horizontally), I can come close to thatdesign goal using standard off-the-shelfcomponents.

The concept of assigning logical "win-dows" on the file's data is essential. In eacharticle I edit, I have numerous categories ofinformation which are logically separate,though related by belonging to the sameentity. There is always the main body oftext of the article; there is the captions listwith subcategories based on the type ofillustrative material being captioned; there isalways a set of summary information such asthe author's name, "about the author," theauthor's address, etc. There are sometimesadditional optional materials such as glossa-ries, boxes of text which are auxiliary argu-ments not part of the main text, etc. Oftenit is necessary to scan one such logicalsubset of the article while retaining asegment of another such subset in view.For example, when checking a glossaryitem, the main text might be scannedwhile the glossary is maintained on thedisplay. Or, when making a change ofphrasing to clarify an author's point, theoriginal text should remain on displaywhile the modification is being made, justas I can always see the original text whenI make pencil corrections in the manualmethod of editing. The ability to allocatemultiple windows pointing to the samedata set is only effective when the displayarea is big enough so that each windowis of nontrivial size.

IBM Compatible Media. . .

The requirement of IBM compatiblefloppy disk media is the only one which isdriven by an external consideration specificto the context of BYTE publications. Ifthe editing software were being used by anindividual in an isolated situation, theremight not be a need for either IBM compati-bility or full size floppy disks. But here atBYTE we have an existing system of pro-duction which employs equipment thatis supplied by IBM which uses floppy diskmedia for temporary storage of manuscriptinformation during the typesetting andproduction process which happens afterthe technical editing of articles. The cleanestinterface to this existing system is to havethe input keying operations performed priorto the technical editing, then physicallytransport one floppy disk along with thesource documents of the article to theeditorial offices. After the technical editis completed, the floppy disk is then re-turned to the production department along

140 BYTE March 1978

Circle 20 on inquiry card.

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with the source documents, with all tech-nical changes effected by the technicaleditors, rather than transcribed by pro-duction editors from penciled or typedcorrections to a printed manuscript.

An Approach to SelectingSuch a System's Hardware

With this rough functional description ofwhat I want, how do I go about convertingthe idea into a working system with off-the-shelf hardware and software? This questionis what caused me to begin a process ofexamining some of the more completeproduct offerings by various manufacturerswhich had the potential for meeting the re-quired specification. The fact that I willeven consider several of the former kitmanufacturers for the personal computingmarketplace as the principal suppliers is

evidence of the maturity of this field asit has grown over the past few years.

My first and most important criterionis that the system must be purchased incomplete form from one manufacturer(complete meaning "assembled, tested anddemonstrated"). I do not want fingerpointing (at least initially) due to conflictsover the ambiguous definitions of differentmanufacturers' hardware and software con-ventions. In my case, this will probably beaccomplished by dealing directly with themanufacturer since we already have anestablished business relationship as a maga-zine; for readers of the magazine this can beaccomplished by using a computer storeas the local equivalent, with the proprietorselling a complete and working systemdemonstrated in the store before purchase.I may mix and match peripherals fromother sources at a later time, but such

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BYTE March 1978

incremental additions or modifications willonly be done with the backup of a knownworking configuration.

The second and equally important cri-terion is that the supplier must be able tosupply a complete set of systems software,already developed and operational, at thetime of delivery of the system. This soft-ware includes a disk operating system, thetext editor framework for the manuscriptediting operations, and the usual macro-assembler, linking loader and compilers ofa "minicomputer-like" small system.

I highly recommend that potential usersof a system either purchase or examine themanuals of the system they intend to buy,going over the manuals for purposes ofevaluating completeness and quality ofhardware and software support. In the pastmonth or so, two examples of excellentdocumentation in a small computer systemhave come to my attention. One example isthe so-called "preliminary" (but not very"preliminary" by most standards of docu-mentation) manual of the Apple-ll com-puter, discussed in the review appearingseparately in this issue. A second example isprovided by a system I am examining as apotential candidate for the editing function:the Technical Design Laboratories' Xitanproduct which has been seen publicly at anumber of shows and computer stores. Irecently travelled to New Jersey to visitTDL at the invitation of Roger Amidon.During that day long visit, aside from theusual rituals of visiting a company manu-facturing for this field, I had opportunityto examine much of their software inoperation, and to examine their version of

a high capacity 80 by 25 character displaywith upper and lower case graphics. I pickedup a pile of approximately 3 inch thicknessfilled with the excellent manuals for theirsoftware, which includes a FORTRAN IVwith nearly complete ANSI features plusextensions, a macroassembler, CP/M byDigital Research as an optional operatingsystem, a data base management system forthe FORTRAN programmer called "Micro-SEED," and the ZTEL text editing languagewhich was the most important attraction ofthe trip. From the documentation, I wasable to learn that much of the capability Iwould like to have for a text editing systemused with manuscripts is likely to be avail-able more or less off-the-shelf in ZTEL.There will be some custom work required, tobe sure: for example, the editor does notsupport multiple editing windows, and willnot be able to symbolically store debuggedtext editing macros on the floppy diskwithout some thought. But it may proveto be most of what I was looking for,especially with the use of two of the 80character by 25 line display boards TDL isnow manufacturing.

At the time of this writing, no decisionhas been made yet as to the details of suchas editing system, nor have we purchasedany equipment. I intend to review themanuals of a number of the manufacturerswho offer good combinations of hardwareand software which are potentially usablein this system concept before any finaldecision and purchase is made. But now thatI have made the investment of reading themanuals, TDL seems to be a company whichis well worth looking at.

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142 BYTE March I978

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Which Brings Me Back to MyOriginal Point. . .

The theme which introduced this digres-sion into editing hardware and software isthat there are machines in existence rightnow, which are marketed as finished pro-ducts, and which, with various degrees ofsoftware support, can be had at moderateprices in the $3000 to $8000 range throughcomputer stores. This class of machines iswhat is needed to do "serious" personalcomputing. The characteristics of this classof machines, which has been maturing latelyin the marketplace, might be given as: 16 Kbytes of programmable memory and up,dual floppy disk drive, terminal, optionallysome- form of printer, and availability in

a fully integrated form which needs noassembly from kits. Styles and configur-ations vary, of course, but the importantpoint is that for the price of a good pickuptruck, one gets a computer which can beeffectively used for both utilitarian andfrivolous computational uses at the whimof its owner. If the processor is an 8080 orZ-80, then Gary Kildall's CP/M operatingsystem sold by Digital Research is frequentlyused with this kind of system, and oftenthere is both a compiled high level language(for example TDL's or Cromemco'sFORTRAN IV compilers) and a macroas-sembler. Rumor has it that PASCAL com-pilers exist which will be available shortlyfor this type of disk based system."

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Western Europe' includes Albania Austria, Belgium Bulgaria Cyprus Czechoslavakia.Denmark Finland. France, East Germany West Germany Gibraltar Greece. Greenland.Holland. Hungary Iceland Ireland Italy, Lichtenstein Luxembourg Malta. Monaco. NorwayPoland, Portugal land Azores) Rumania Spain (and Canary islands) Sweden. SwitzerlandTurkey, United Kingdom. USSR Yugoslavia All other regions' includes all othercountries oulside the US S. Canada

Use the numbers to identify your plant activity and your ownwork. If more than one activity is involved, use the code numberfor the most prevalent. Note; if you select "other" for work andplant code or "other personnel" for job function code, be sure toexplain on the lines provided.

WORK AND PLANT (Enter codes) Plant Your own work

1. Large computers

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Aircraft, missiles, space and ground support equipmentOceanography and support equipmentMedical electronics

Industrial companies within OEM incorporating electronicsequipment in their end product, not elsewhere classifiedIndependent research, test, and design laboratory and con-sultant (only if you are not connected with a manufacturingcompany)

Government agency and military

Industrial companies using and/or incorporating any elec-tronic products in their manufacturing, research, or develop-ment activities

23. Communication (radio, TV, police)

3.

4.

5.

6.

7.

8.

9.10.11.12.13.14.IS.16.17.IS.19.

20.

21.22.

Transportation services (airline, railroads, etc.)Computer and data processing services: service bureaus, soft-ware services, timesharing, consultingAll other commercial usersPower generation equipment manufacturerPower production (atomic, electrical, etc.)Power generationPower transmissionPower distribution

Utilities, except power (telephone, telegraph, pipelines, etc.)Distributor

School, university, or libraryOthers (explain)

24.

25.

26.27.28.29.30.31.32.33.34.35.

JOB FUNCTIONS (Enter code)

1. General and corporate management

2. Design and development engineering (circuits, components,equipment systems)

3. Engineering services (evaluation, quality control, reliabilitystandards, test)

4. Basic research

5. Manufacturing and production

6. Engineering support (draftsman, lab assistant, technician)

7. Purchasing and procurement

8. Marketing, including sales

9. Computer systems operations

10. Engineering systems planning and design (utilities)

11. Operations including construction & maintenance (utilities)

12. Dean, professor, instructor, etc.

13. Student

14. Other personnel (explain)

JOB CATEGORY (Enter code)

1. Management

2. Engineering

Mail the completed application and full remittance (check payable to IEEE) to: IEEE Service Center, 445 Hoes Lane, Piscataway, NJ 08854.

BYTE March 1978 145

r

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A hypothetical assembly language called MIX has been developed by the author toillustrate programming examples throughout the series. MIX is easily convertible to otherassembly languages.

Prof Knuth writes with style and wit (among many memorable quotes is one fromMcCall's Cookbook!). This classic work belongs on the reference shelf of everyoneseriously interested in computer science.

Art of ComputerProgramming

146

BYTE March 1978

Projects in Sight, Sound and Sensation

by Mitchell Waite. Dedicated to "all spacecowboys." Detailed theory and practice ofseven fascinating amateur electronic pro-jects, along with a detailed appendix on howto make PC boards. $5.25.

What to Do After You Hit Return or

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The BITS Catalog

At last! The BITS catalog is here! We've carefully screenedand evaluated scores upon scores of microcomputer booksand reference texts. Now we offer what we believe to bethe most authoritative, most comprehensive catalog ofpersonal computing publications available anywhere. It's areference work in itself. Catalog sent with every order. Orsimply circle the BITS number on your BYTE reader servicecard.

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BYTE March 1978

147

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The Altair

(S-100) Bus

Forum:

PCC77

John McCallumComputer Science DeptYork UniversityDownsview, Ontario M3J IP3CANADA

TechnicalFopum

An Altair (S-100) forum was held atPersonal Computing 77 in Atlantic City NJin August 1977. The forum, led by WilliamGoble, dealt with some of the problems of,and the future of the Altair (S-100) busstructure. As secretary for the group, I havetried to collect the ideas from the forum. Ihave also taken some liberties in adding addi-tional information gathered at PCC 77relating to the discussions.

Expansion of the Bus

1. Eight extra lines are not available onthe bus for a 16 bit data bus.

2. 16 standard address lines are availableplus four semistandard (A16 to A19)lines used by Technical Design Labs(TDL).

3. Expansion to a 16 bit data path can beachieved by.

a. Ignoring conflicts on some Altair(S-100) lines, using them and en-suring your system will work (12 to17,59 to 66).

b. Multiplexing data down the presentdata lines a byte at a time (theAlpha System does this, as does the8080, etc, during a multibyteinstruction): this entails a smartprocessor board. It could slow theprocessor timing or cause speedlimitation problems with the bus.(This can also be used with 12 bitprocessors.)

c. Using two parallel Altair (S-100)boards: a wasteful technique, butone which simplifies some problems.

d. Using a ribbon connector on thetop of the cards to connect extradata and address lines: this meansthat only the expanded precisioncards are affected. Noise problemscan be reduced in the connectorby alternating ground lines andpower lines with data and addresslines. (32 data and 32 address lineswould allow for any foreseeableexpansion.)

Method b is most practical for immediate

148

BYTE March 1978

Circle 74 on inquiry card.

expansion. Method d is needed for long-range expansion for 32 bit microprocessors(perhaps as a 16 bit path used in conjunctionwith b to achieve 32 bits).

Problems with the Altair (S-100) Bus

1. Noise

Two examples of bad Altair (S-100)bus layout were cited. The noise onthese buses was such that intermittentoperation of the system resulted.Noise on the bus can be caused by thefollowing:

a. Crosstalk

Crosstalk occurs between ad-jacent lines along the length ofthe bus. The bus consists of themother board plus the tracesbefore ending at individual com-ponents on all boards in the system.High frequency signals are likely tobe transferred from line to line.Spacing layout, construction mate-rials of the mother board, andreflections (see next section) canall seriously affect crosstalk.

b. Reflections

When a signal reaches the end ofthe bus, part of the signal is reflec-ted. [Reflection can occur with anywavelike phenomenon, includinglight waves, sound waves, or highfrequency electrical signals, it hap-pens when the wave strikes amedium of different characteristicsthan the original medium (differ-ent density, for example, in thenew medium).] Reflection can bestopped by proper termination ofthe line. Two types of terminationdevices are in use in some Altair(S-100) bus designs. The effectof present terminators has notbeen studied in detail (even bythe designers) to get comparativeeffects. However, the general con-sensus is that any attempt at ter-mination is good.

2. Speed

There is a limit to the Altair(S-100) bus's speed. This occurs dueto a propagation delay of from 1 to10 ns down the bus, and as a result ofnoise from reflection and the increaseof crosstalk with speed. The speedlimit changes with different designlayouts. One manufacturer who hadrun computer simulations on theirdesign would claim only 4 MHz withcomplete confidence (it was thecleanest system I saw). With at leasttwo other systems running into trou-

Forum Attendees:

William M GobleJon E AveryMichael L SheaRobert H RoseVincent MoscaritoloBing HuangPeter Robinsonetal

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BYTE March 1978

149

Deep Within Every

Novice Lurks a

Computer Hacker

Waiting to Get Out

Help free the novice in your life withtwo outstanding selections from BITS. . .

Your Home Computer, by JamesWhite, is a clearly written nontechnicaldescription of personal computers thatrequires no prior knowledge of computersor electronics. The emphasis is on under-standing; over 100 illustrations are included.Topics include: computing and you; com-munication inside a computer; computerthought processes; fixed memory; inputsand outputs; peripherals; systems com-ponents; how to choose a microcomputer;and so on. Your Home Computer is theideal book for readers who thought theycould never understand how computerswork. And the best part is that it's easyand fun to read. Yours for $6.

The perfect book for the layman orwoman. How You Can Learn to Live WithComputers is a lively account of theseubiquitous machines and their role inpresent society. Author Harry Kleinbergbegins with some elementary logic andshows how a simple hardware circuit can beused to illustrate logical concepts. $8.95.

BITS Inc70 Main StPeterborough NH 03458

For ease in ordering, use the coupon onpage 147, writing in the name(s) of thebook(s) you want.

Please note that processing may exceed 30days in unusual cases.

bles even at 2 MHz, there is a realquestion of bus design and propertermination. Claims of some manu-facturers with fast buses were in openquestion.

Conclusions were that if you havenoise problems, add a terminator(terminator boards are available) andsee what happens. On a well-designedsystem with proper termination andshielded layout of the mother board,the real speed limit should be about10 MHz. On nonterminated unshieldedsystems, the speed limit will probablybe about 3 MHz. Some study is neededto know more exactly, however.

3. Incompatibility

Several of the originally undefinedpins have now been multiply defined(12, 13, 14, 56, 57, 58, 59, 60, 62,63, 64, 65, 66, 67). These all havevarious definitions. There is no realway to correct or prevent these in-consistencies, since the individualdesigner can arbitrarily use the lines.For the user, however, we need toknow the exact bus structure for eachboard so we can check for compatibil-ity with our own systems. Thus allAltair (S-100) bus products shouldinclude a bus description showingwhich leads used on their individualboards are input, output, bidirectional,unused and speed (if clocks). A list ofcompatible and incompatible boards,and perhaps some outline of how toachieve compatibility would also behelpful.

In any case, the following de factostandard usage of lines is building updue to usage:

Pin 14

Pin 60Pin 61Pin 62Pin 63Pin 66

Battery backup (Seals, IthacaAudio) (also being wired to topof board by most battery backupboards)

A16 Address (TDDA17 (TDD

A18 (TDD

A19 (TDD

RFSH Refresh for dynamic mem-ory (Z-80 systems) (Cromemco,SD Sales)

4. Electrical

Some mention was made of govern-ment regulations and lack of shieldingand interlock devices on boxes housingmicroprocessors. A question of ULapproval of a device with differentvoltage sources on adjacent connectorswas also raised. No one knows thestatus of the rumors, but it couldcause problems for commercially pack-aged devices in the future.

150

BYTE March 1978

Circle 10 on inquiry card.

5. Duplication of data lines

With bidirectional bus drivers read-ily available, the use of eight extralines for data in and data out is ques-tionable. Some manufacturers aremoving from data in and data out tobidirectional usage. This can causedifficulties in some designs of memoryin a system. Although separate data inand data out lines cause inefficient useof space, there is some use in boarddesign. Also, despite any inefficiencies,it is the standard; but on any busexpansion to 16 or 32 data lines,a bidirectional bus would be best.

General Comments

The Altair (S-100) bus has its problems.However, it is widely used (over 100 manu-facturers produce products for it). It isspeed limited, but then, the PDP-8 has notchanged speed much in a decade. (ThePDP-8 still compares well in benchmarkstoo!) Inconsistency in Altair (S-100) linedefinitions has usually caused few problemsto users. Noise problems on the bus canusually be cleared up by adding terminationor shielding, or by getting a new motherboard. It has proved to be a workable basisfor many design applications.

However, many designers will see itsobvious faults and readily define a simplerbus, so we will see new buses in the future."

REFERENCES

MITS, Theory and Operations Manual—Altair 8800.

D Denney and J Broom, "Why Not a Standard100-Wire Bus Structure," IEEE Computer,October 1976, pages 57 to 58.

WM Goble, "Introducing the S-100: StandardSmall Computer Bus Structure," InterfaceAge, June 1977, pages 66 to 79.

BYTEs Bits

The Passing of a Pioneer

It is with some sadness that we notethe passing of one of this century'sgreater innovators, Dr Peter GoldmarkSr. Included in more than 150 inventionswere pioneering contributions to prac-tical long playing record technology.Dr Goldmark's recent work since beingretired from CBS Laboratories concen-trated on innovative uses of cable tele-vision, domestic satellites and electronicspublishing — all areas which border onmany of our readers' interests as users ofcomputers."

StructuredProgramming

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An Equal Opportunity Employer, M/F

J

Circle 11 on inquiry card.

BYTE March 1978

151

CIE Net: A Design for a Network

Mike Wilber920 Dennis DrPalo Alto CA 94303

The CIE ProtocolsOverview of the Protocols

Two kinds of protocols are needed totransmit messages from one CIE to thenext. First the stations that want to talkto one another must agree on the languagethey will use for talking to one another, andsecond, the stations along the path betweenthe two stations must agree on the languagethey will use among themselves for trans-mitting messages between the end points.For brevity, we can call the first one anend-to-end protocol and the second aninterstation protocol. All these protocolsshare an important property that can beused to help them coexist with other non-CIE Net protocols, be they experimentalvariations or completely different proto-cols: each interstation transmission and eachend-to-end message starts with a code thatidentifies the protocol set being used. Inaddition, each of the different end-to-endmessages contains a crucially placed param-eter line that identifies which (of a possibleset of variations) is the appropriate way tointerpret it.

The interstation protocol itself breaksdown into two parts. When the stationsfirst establish a connection, they mustfirst negotiate the parameters they will useto initialize themselves. Once the stationsare prepared to proceed, then they need aprotocol that is adapted to the transmissionof network traffic and additional inter-station control information. For brevity, wewill call the protocol in which the initialnegotiations are transacted the initial con-

nection protocol. Similarly, the protocolfor transmitting interstation control in-formation will be called the station controlprotocol. Since network messages willtypically be so long that stations will gen-erally wish to subdivide them into trans-mission blocks, we will call the main inter-station protocol for handling network trafficthe block framing protocol.

Most interstation traffic will be con-cerned with the transmission of networkmessages, so I propose optimizing the inter-station protocol toward the block framingprotocol in this fashion. When two stationsare first connected, they will use the initialconnection protocol to establish the param-eters for all future conversations over theconnection. The initial connection protocolis not very highly coded and so gains a verywide accessibility to a wide variety of pro-tocol interpreters at the cost of inefficientutilization of the interstation channel.(Thus, the initial connection protocol can beused to establish the identity of the protocolset to a protocol interpreter that is pre-pared to handle protocols quite differentfrom those I am proposing here. In fact, theinitial connection protocol identifies itselfin the first four characters transmitted overthe connection.) At the end of the initialconnection protocol, the stations agree tosubsequently use the block framing protocolfor all future transmissions. That protocolis quite highly coded for efficient utilizationof the channel bandwidth and is optimizedto handle transmission blocks of networkmessages; the station control protocol is

152 BYTE March 1978

of Community Information Exchanges

Part 2: Protocols

<BNF description>

<equation>

< formal word>

<alternatives>

<sequence>

<item>

--informal description^'•'.literal item>

<double quote><optional item>

<equation> [ <BNF description^ |

<formal word:- ":; — ' <alternatives>

"<" any text not including a right pointy bracket ">"

<sequence> [ "!" <alternatives> |

<item> [ <sequence> |

<formal word:- ! <informal description> !<literal item> ! "'optional item> !" { " <alternatives> " ]• "

any text (possibly including <formal word>s or <double quote>swithin parentheses), but otherwise including none of the (six)brackets used in this definition, no exclamation point (nor any<double quote.'-'-)

'double quote.'- the text to be used (including no ---'.double quote>s)•".double quote.'-'- !

a sequence (of three <double quotes>s) representing a single(<double quote>)

"[" <alternatives> " I "

Figure I: Backus-Normal Form (BNF) Notation. I occasionally show the format of networkmessages, etc, in a slightly formal language very close to BNF. In this notation I present a bunchof equations that define formal words (enclosed in <pointy brackets>) in terms of other formalwords, things that must appear literally in the thing being defined (enclosed in "doublequotes") and informal English descriptions (not enclosed in anything at all). Each equationhas a formal word on its left side, the definition sign (:: =), and the definition on the rightside. A definition can include a list of alternatives (separated by exclamation points), of whichexactly one must be chosen. Each alternative is a sequence of items that appear in the thingbeing defined (in the order they are indicated). Each item can be a formal word (whose defini-tion is given in another equation), an informal description, a double-quoted literal item, anoptional item (enclosed in [square brackets]) or a list of alternatives (enclosed in ( curlybrackets } ). (Also note that, in spite of the fact that all literal items in my BNF definitions willbe given in lower case, the distinction between upper and lower case is to be ignored. Thus,the literal "reply" should not be distinguished from "Reply," "REPLY" or "rePIY.") Forexample, my version of BNF can be defined by the above equations by using these same con-ventions.

BYTE March 1978

153

handled by the block framing protocol asa special case.

The end-to-end protocol also breaksdown into two parts. There is a commonmessage frame, and there are five kinds ofend-to-end messages that share it. Themessage frame shows, at the very least, theserial number of the protocol set in use andthe address to which the message is beingsent. It can also include some informationfor error detection, acknowledging intactreceipt or both. The message frame can alsoinclude a unique identifier for the message.

The five different types of messages aredistinguished by a characteristic word justat the point where their formats diverge.Finally, the message frame provides forencryption, compression or segmentationof the message contents. Encryption isespecially important if people are to trust thenetwork to transmit their private messagesthrough an unknown number of computersbelonging to people whose intentions areunknown. Compression is provided just toeconomize the use of narrow channels. Auniform means of segmentation lets people

<interstation transmission>

:: = <initial connection transmission> !<interstation message block>

<initial connection transmission>

:: = <greeting

<greeting>

<offer>

<short addr part>< offer tail><short sender addr>

<acceptance><denial><error report><reset command>

! <offer> ! <acceptance> ! <denial> !<error report> ! <reset command> !<final initial connection transmission>

= "hiya" <protocol number> "," (the sender's <net address>)

":" (a <number> giving the maximum number of charactersthe sender can accept in an <interstation transmission>) <crlf>

= "lets" <short addr part> <offer tail>

= ":" <short sender addr> ","

= "maxbuf —" <number> <crlf>

= "0" (if the sending station's <net addr> has a lower ZIP code thanthe receiving station's <net addr> or if their ZIP codes are thesame and the sender's <ZIP code suffix> is the lower); and"1" otherwise

= "yeah" <short addr part> <offer tail>

= "nope" <short addr part> <offer tail>

= "oops" <line> <crlf>

= "tilt" <line> <crlf>

<final initial connection transmission>

:: = "doit" <line> <crlf>

<interstation message block>

<block head>

<block tail><block body><block contents><data contents><block body checksum>

<ctl wd> ::

<block head> <block tail> <crlf>

= (the radix-41 representation of a <ctl wd>)

(the <ctl wd>'s 1-digit radix-41 checksum)

= <block body> <block body checksum>

= (the radix-41 representation of the <block contents>)

= <special contents> ! <data contents>

= the data the sender wants to send

= (the <block body>'s 2-digit radix-41 checksum . . .see the text)

= (a 16-bit word laid out as follows; see the text for explanationsof the fields)

bits

<block length>

-3-bits

<acks>

bits

<block #>

-« 1-

bit

<xmitdir>

-1 *-

bit

<special>

<special contents>

(a sequence of 16-bit words, each having an operation code in themore significant 8-byte and perhaps some data in the lesssignificant 8-bit byte; see the text for more details)

Figure 2: Interstation transmission formats. The interstation transmissions of a CIE Net usethe syntax of this definition. The two main components of the protocol are initial connectiontransmission used to negotiate parameters of initialization between the two stations, and theinterstation message block or block framing protocol which is used for the bulk of networktraffic. The design is optimized for the block framing protocol (end to end message frame),since this will be the predominant form of transmission on the network.

154

BYTE March 1978

send files that are much longer than thenetwork can gracefully handle as singlemessages. The five different kinds of mes-sages sharing the message frame are:

• mail for people;

• file retrieval and storage;

• messages directed to other nets;

• messages containing or requestingstatistical information; and

• replies to the other four classes ofmessages.

The Block Framing Protocol

The block framing protocol provides anumber of features to ensure that messagesare reliably transmitted between adjacentstations. (It bears some resemblance to theARPA Net's Very Distant Host protocoland to a protocol known as DDCMP ofDigital Equipment Corporation's DECnet.)It provides for error detection and retrans-mission. It provides for the proper se-quencing of blocks in the face of lost orduplicate error-free transmissions. It willaccommodate the half-duplex line disciplinewhere it must, and it will capitalize on thefull-duplex line discipline where it can. Ituses the radix-41 representation for arbitrary

binary data so that the programs that relaymessage blocks can be written in stringBASIC. It also provides facilities to allowadjacent stations to test their connectionand programs.

Message blocks have a format that isshown in figure 2. A block contains a headand a body; to provide error resistance onthe telephone line, the head and body areeach represented in a special radix-41 code(to be described in the third part of thisseries next month), and are separatelyprotected by check digits. The block headhas a 1 digit checksum, which is the sum(modulo 41) of the three (radix-41) digitsrepresenting it. The body, on the otherhand, has a 2 digit checksum that makes thesums of the odd numbered (ie: first, third,fifth, etc) and even numbered (radix-41)digits of the <block tail> both zero. Forexample, if there are an odd number ofdigits in the <block body>, then the first<block body checksum> digit protects theeven numbered <block body> digits. (Thus,the checksum calculation can proceed in-dependently of the <block length>.) Thisinterlacing helps resist noise that comes inbursts, as is most often the case with phonelines: noise is relatively unusual, but when it

Note: The third part of thisseries contains full biblio-graphic citations of selectedcogent references, such asARPA Net specifications.

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BYTE March 1978

155

occurs, it typically lasts long enough to wipeout several consecutive characters. With thetransmission coded as several interlacedgroups of digits that are separately pro-tected, the chances are quite good that aburst of noise will be detected in at least oneof the groups. Berlekamp observes that noerror detecting code can resist more errorsthan can be represented by the check digits;two radix-41 check digits can detect 1681 ofthe possible error combinations. The particu-lar scheme mentioned here is optimized todetect errors that are confined to two adja-cent digits, but it can also detect isolatederrrors.

Transmission blocks have numbers, as-signed by counting (modulo 8) from zero;blocks going in each direction are numberedindependently. Each transmission blockincludes its own number and the number ofthe next expected block in the other di-rection. Each station remembers the blocknumber its partner most recently expectedand takes care to get no more than fourblocks ahead of its partner. Any arrivingblock that is in error is rejected, and thustreated just the same as lost transmissions.A station that has four unacknowledgedblocks outstanding can then conclude thatthe first of them was in error and shouldattempt to retransmit it. The duplicatetransmissions resulting from this procedurecan be detected because the window is halfthe size of the total space of block numbers:if an arriving block has the number of ablock that has been received since the lasttime it was expected, it is a duplicate andcan be discarded.

The fields of a <block head>, then, areas follows:

• The <block length> is the number of16 bit words in the <block contents>.

• The <acks> field is the number of thenext expected block.

• The <block #> field contains thenumber of this transmission block.

• The <xmitdir> field is the <shortsender addr>.

• The <special> flag is a 0 if the <b!ockcontents> are <data contents>, or a1 if they are <special contents>.

A special block contains a number of16 bit words that are used for maintainingthe interstation link. They are distinguishedby an operation code in the more significant8 bit byte and can optionally contain data inthe less significant 8 bit byte. They are:

0 — The message is complete, ie: the nextdata block starts a new message.

1 -Turn the line around. This one isused when the line is a half-duplex line,and so the stations must take turnstransmitting.

2 — This block is just an acknowledge-ment; don't reply to it.

3 — I have buffers for some more datablocks; please send them. The numberof data blocks that can be accommo-dated is given by the optional data andoverrides all previous allocations.

4 — Goodbye, I'm signing off. Don'texpect any more transmissions fromme.

5 — Please reset yourself, I'd like togo back to the state of swapping<greeting>s.

6 — Echo this message, please, I'd like tosee if it got to you OK. (Only the<block contents> are echoed.)

7 —This is the echo you requested. (Allecho request bytes in the block arechanged to echo reply bytes when theblock is echoed.)

8 — Ignore the data part of this word.

9 — Something is wrong.

10 —Discard this block (but acknowledgeit).

11 —Selective negative acknowledgement:the optional data part gives the numberof a block whose head arrived intactbut whose body did not.

12— Ignore the <block #> of this blockand process its <special contents>immediately. (This word must be thefirst in the <special contents> toassure proper processing of the block.)

Note that these protocols say nothingabout certain necessary operations. Theyare the steps by which the adjacent stationsrendezvous and include operations likephoning a station's host computer, logginginto its operating system and provoking theappropriate programs. The details of theseoperations are idiosyncratic to the host sys-tems and cannot profitably be specifiedhere. These protocols only cover the com-munications between the stations aftertheir rendezvous has been established.

The End-to-End Protocol

The end-to-end protocol specifies that anend-to-end message consist of a uniformmessage header and one of five differentkinds of message contents; the formats areshown in figure 3. In addition, the <messagetail> (wherein resides the message contents)can be encrypted or compressed, or cancontain only part of a long message. The<message head> contains all the informa-

156

BYTE March 1978

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BYTE March 1978 157

Figure 3: End to endmessage frame formats.This BNF text describes asyntax for data sent usingthe interstation protocolfor each link of a trans-mission. Note that buriedin the message protocol isthe address informationfor both the source andthe destination, All mes-sages passed along the CIENet are strings of datacreated according to thisformat.

tion necessary for the automatic generationof replies in the reply protocol. Replies areat the option of the sending CIE. The firstword of the <message tail> shows which ofthe five kinds of message tail it is, and therest of the <message tail> is completely un-specified in top level of the end-to-endprotocol. Otherwise, the first word of the<message tail> indicates that the tail isencrypted, compressed or partial, and asimilar uniform format shows the truecontents. Encrypted and compressed tailsalso contain a parameter line giving detailsof the procedure used, so that the sourceand destination of the message can agree ona number of alternative procedures.

It may not be obvious at first glance whymessage replies should be optional. Actually,there are two reasons, both of which derivefrom a desire to reduce network traffic byeliminating superfluous replies. Since theoverall design for a CIE Net includes a veryreal possibility of lengthy transmissiondelays, the sending CIE may have lostinterest in proper transmission of a messagelong before its reply arrives. Thus, the send-ing CIE is allowed the option of omittingany request for a reply just to simplify itsown bookkeeping. On the other hand, manyARPA Net messages are sent that don't needreplies on the lowest level either becausethey are acknowledged on a higher level, or

<message><message head>

<protocol number><message length>

<number><crlf>

<dest net addr><net address>

<gap>

<ZIP code suffix>

<reply head>

<source net addr>

<message i.d.>

<date>

<message tail><enorypted tail><parameter line><line>

<compressed? tail><compressed tail><partial? tail><partial tail>

<real tail>< reply tail>

= < message head> < message tail>

" [ <message length> ":" <gap> ]<reply head> ] <crlf>

= <protocol number><dest net addri

<stats tail>< gateway tail>

= <number>

= the number of characters (in the <message> expressed as a<number> and counting each <crlf> as two characters)

= a decimal number

= a carriage return immediately followed by a line feed

= the address of the destination (expressed as a <net address>)

= ["usa"] <gap> the ZIP code for the station's address "—"<ZIP code suffix>

= any sequence of zero or more tabs and blanks

= a 3-digit number from 000 to 999 inclusive

= "(" [{"rsvp" ! "later"}":" <gap>] <source net addr>[":" <message i.d.>] ")"

= the address of the message's sender (expressed as a<net address>)

= <date>{"," ! " "}any text that (taken together with the

<source net addr> and the <date>) will uniquely identifythe (<message>) and that includes neither a carriagereturn, a line feed nor a parenthesis

= the month (expressed as a <number>) "'/•"the day (expressed as a <number>) "/"the year (expressed as a <number> with two or four digits)

= <encrypted tail> ! <compressed? tail>

= "crypt" <parameter line> <crlf> <compressed? tail>

= parameters for the indicated process (expressed as a <line>)

= any text including neither a carriage return nor a line feed

= <compressed tail> ! <partial? tail>

= "crunch" <parameter line> <crlf> <partial? tail>

= <partial tail> ! <real tail>

- "partial (" <source net addr> ":" <message i.d.> ")"{"section" <gap> <number> !"bytes" <gap> <number> <gap>"thru" <gap> <number> }<gap> "of" <gap> <number> <crlf>the indicated piece of a (<real tail>)

= <mail tail> ! <file tail> ! <reply tail> ! <stats tail> ! <gateway tail>

= "reply"

[ "mail " ! "file " ! "reply " ! "stats " ! "gate " 1

|"ok" ! "bad" ! "please" ! "unknown" ! "echo ! "discard"}

":" <gap> [ (the original message's

<source net addr> or <dest net addr>)]

(the original message's <message i.d.>)

<crlf> (any text)

= "stats " any text

= "gate" any text

158

BYTE March 1978

because the sender really cares very littlewhether they arrive at all. It would seemthat, on the assumption that the samephenomemon will arise in a CIE Net, thesending process should be allowed to tellits CIE not to request a reply to be sentwithin the end-to-end protocol level. Notethat a <reply head> containing a <messageID> must be included in a message forwhich a reply is expected at almost anylevel.

End-to-end messages should be arbitrarilylimited in size to facilitate their transmissionthrough volunteer relay stations and inter-mediate ClEs that are only loosely organizedinto a highly variable network. The con-sideration here is buffer allocation in theintermediate CIEs because they must handlewhole messages rather than the smallertransmission blocks that are the concern ofthe relay stations. (Note that messages ofany length can still be accommodated byseveral messages containing the appropriate<partial tail>s.) Probably the appropriatesize would be somewhere between 1000characters and 8000 characters; the lowerlimit is that of a single packet in the ARPANet (which, according to Kleinrock, et al,can entirely contain 89% of the ARPA Netmessages), and the upper limit is about the

point at which operating systems begin tohassle their users. Message sizes in a CIE Netwill probably be longer than in the ARPANet because of the absence of the flurry ofmessages the ARPA Net needs to set up (anddelete) the connection needed for the "real"message. The statistics of ARPA Net mail areprobably a better indication of what toexpect in the CIE Net: those messagestypically run from 600 to 1400 characters.However, a CIE Net will probably contain alot of messages that are even longer for tworeasons. ARPA Net mail statistics excludethe transfer of files containing computerprograms or extended documents; both ofthose tend to be longer than the install-ments of a running dialogue. Also, peoplewho are relatively unfamiliar with the ARPANet mail facilities tend to send messages thatare 3000 to 8000 characters long, ratherthan the more usual shorter messages; thosepeople are probably more representative ofthe participants in a CIE Net, at least whenit first becomes operational. Thus, thestandard maximum message size in a CIENet should probably be somewhere between5000 and 8000 characters.

The Mail Protocol

The mail protocol will look familiar if

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Figure 4: <mail taif>formats. Within the mes-sage frame protocol thetype of message is de-termined by the type oftail applied to it. This<mail taif> enters thesyntax of figure 3 as oneof the options for a <realtaif>. Mail messages con-tain the <mail body>,which is the message beingsent, along with a varietyof items specific to elec-tronic mail activities car-ried over the net.

you know about the ARPA Net mail pro-tocol. The protocol (see figure 4) is a com-promise between the current ARPA Netmail protocol, its proposed replacementand the different requirements of a CIENet. It specifies a <mail ta.il> to consistof a bunch of header lines, a blank line, andthen the text of the mail. The header linesare intended to be intelligible both to ahuman and to an automatic message han-dling program; the text of the message isonly intended to be intelligible to a human.The <user name> in a <mail address line>is intended to be a name that is intelligibleto the appropriate destination CIE, and the<user name> in the <mail sender line> isintended to be intelligible to the sendingCIE if a response is generated by a highlyautomated mail processing program. Theonly reservation is that a distinguished username, manager, is to be reserved for mailsent to the people operating the CIE bypeople who don't know their names.

The header lines are grouped at the frontof a mail message and are set off from the

<mail body> by an empty line. The headerlines are suggestively titled, but two of themshould be explained somewhat further. The"from:" lines serve as signatures, and the"sender:" (or "sent-by:") line tells whoactually sent the message; the <mail senderline> can start with "from:" if the personsending the message also signs it. The "en-closures:" line indicates the parts of the<mail body>; that can profitably bethought of as separate enclosures, such asother mail messages or files being forwarded.The <number>s are offsets into the <mailbody>, with the first character of the<mail body> being numbered zero. Anyenclosure whose end is implied by the be-ginning of the next enclosure or the end ofthe message can be indicated by a singlenumber; other enclosures must be indicatedby a hyphenated pair of numbers. Then, theautomated mail systems have the informa-tion they need to help the recipient detachthe enclosures. Any enclosure can, at thesender's option, be described by a parenthe-sized comment to further aid the recipient.

<mail tail><mail head>

<mail address lines><mail address line>

< colons-addresses:.-<individuals>

< individual"-'-<mailbox>

<user name.--

< personal name><gapl><group><name>

< mail sender line> :<optional mail headers'-

<optional mail header: ■

<date header>•'.enclosure header.'--<enclosure list><enclosure item>

<mail body'

= -Cmail head> <orlf> <mail body>

= "mail" <gap> <mail address lines: ■< mail sender line>[ <optional mail headers: ■ |

= -'mail address line> [ <mail address lines> |

= { "to" ! "cc" ! "bec" } <colon> <addresses> <crlf>

= <gap> ":" <gap>

= { <individuals> ! <group> } [ ";" <addresses> |

= <individual> [ "," <individuals> |

= • .mailbox--- [ "(" <personal name> ")" |

- <user name; ■ { "@>" ! <gapl > "at" <gapl> }

<net address>

- <name>= <name>

= (a <gap> containing at least one character)

= <name> <colon> [ <individuals::- |

= (any sequence of letters, digits/blanks, periods and dashes, but notcontaining the string "at'.'.)

= { "from" ! "sender" ! "sent-by" } <colon> <individual> <crlf>

= <optional mail header> <crlf> [ <optional mail headers> ]

= <date header> ! <enclosure header"- !

"in-reply-to" <colon> <source net addr> <colon> -Cmessage i.d.>

{ "from" ! "keywords" ! "password" !

"precedence" ! "authentication" !

(any sequence of letters and dashes not otherwise specified here for

the left end of a line in a <mail head> ) j

<colon> <line>

= "date" <colon> ■[ <date> ! <line> }

= "enclosures" <colon> <enclosure list >

- <enclosure item> [ "," <enclosure list> |

= -'gap-- <number> [ "—" <number> |[ <gap> "(" <name> ")" |

= the mail's body

160

BYTE March 1978

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Large amounts of junk mail can be a realproblem when the recipient must pay tostore it for the time before examining itThere is, however, a partial solution thatinvolves a novel use of passwords. A CIEcould offer its users the option of splittingtheir file for incoming mail into two pieces,one having a negotiated maximum size andthe other requiring a negotiated passwordfor admittance. Then, an incoming mailmessage would be placed in the "goodguy"mail file if it included the proper passwordin its header; otherwise it would be placed inthe junk mail file if there was room; other-wise it would be rejected. Presumably,people using such a facility would spreadtheir goodguy mail password around andoccasionally change it when it eventuallyspreads too far.

The most glaring flaw in this scheme isthat a single energetic source of junk mailcould prevent people from receiving legiti-mate mail from people who, for any of alarge number of conceivable reasons, didn'thappen to know the appropriate goodguypassword.

The File Protocol

The file protocol illustrated is not toowell thought out and should be taken asan extremely skeletal suggestion of what afile protocol should look like. Its mainnotable features are that it leaves file nameformat and user access assertion largelyunspecified so that idiosyncrasies of diversehost systems can be accommodated grace-fully. It allows a CIE to tell a second CIE tomove a file to a third CIE in a manner simi-lar to the DAP portion of the DigitalEquipment Corporation's DECnet. Its mostobvious shortcoming is that it treats files asindivisible atoms; perhaps it should also in-clude a facility to subdivide a file likeDECnet does. This would help conservetransmission bandwidth and buffer spaceby allowing people to selectively move smallparts of files when appropriate. However,that would commit the <file tail> format tosome particular file structure, and that com-mitment would be stronger than the com-mitments implicit in the <partial tail> or<enclosure item>. I omit that facility be-cause it will be of limited utility at first, it iswell-isolated from the rest of the protocols,it is highly arbitrary, and it can be addedlater.

One should note that the file protocolinvolves sending information (eg: passwords)through the net that, one might think, wasbetter kept out of hands that are not com-pletely trusted. That's not quite the case,however. Those passwords should more

properly be thought of as very highlyspecialized tokens of limited utility. Forexample, a process requesting a file re-trieval could arrange with its CIE for thestorage of one file of a specified maximumsize by file retrieval from a particular foreignCIE. Part of the negotiation would involvethe file requesting process and the CIEagreeing on a password to be used just forthat purpose (and then discarded by theCIE). Then, that password would be in-cluded in the file retrieval request and usedin the file storage request it sends back withthe requested file. The negotiation processwould presumably also include the choice ofan account to which the required file spaceshould be charged; then the <file storeinfo> wouldn't need to contain accountnames.

The file protocol includes a couple ofthings that can be idiosyncratic to the CIE'shost system. The information (and its for-mat) contained in <file access> and a <filename> varies widely between operatingsystems, and so it would be inappropriatefor these protocols to say anything moreabout them than that they cannot contain a<crlf>. By the same token, a fair portion ofthe operating systems in captivity cannotgracefully append information to a file thatpreexists; a CIE with such a host should feelfree to reject a file message whose <filestore info> contains the "appe" verb. Inother words, even though this specificationgives the format of a request to appendinformation to an extant file, it does notrequire that such requests be acceptableto all CIEs.

The Reply Protocol

All replies in the end-to-end protocols aresent via the reply protocol. This is at vari-ance with both the ARPA Net and DECnet,which extend each of their other protocolsto include a separate idiosyncratic reply pro-tocol. The reason for the difference is thatboth the other nets are oriented towardconnections, over which flow many relatedmessages, rather than being oriented towardthe messages themselves. (Of course, themessage orientation of a CIE Net is derivedfrom the way it allows for very long trans-mission delays, which would require muchlonger connection lifetimes.) The <replytail> can optionally include a word (eg: file)giving the general area of its relevance; itthen contains more specific information onthe disposition of the message for which itis replying or requesting a reply.

The reply protocol covers use of the<reply head> and the <reply tail>, whoseformats are shown in figure 3. A <message>'s

162

BYTE March 1978

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BYTE March 1978

163

Figure 5: <file tail> for-mats. Another option for<real taif> in figure 3 is a<fi/e taif>, used when thedata sent in the end to endmessage frame is an arbi-trary data file.

<file tail>

<file commands>

<file retrieve>

<file access>

<file name><file store info><file store>

= "file" <line> <crlf> <file commands>

= <file retrieve> <crlf> [ <file commands> J! <file store> <crlf>

= <file access> <crlf>

"retr" <gap> <file name> <crlf>

"dest" <net address> <crlf> <file store info>

= "acoe" <gap> (a <line> that will convince the recipient of this<message> to grant the required access, typically containinga subscriber name, password and account)

= <line>

= <file access> <crlf> { "stor" ! "appe" } <file name>

= <file store info> <crlf>

"data:" <line> <crlf> (the file's contents)

<reply head> gives it a "name," which itneeds if it is ever to be acknowledged inthe end-to-end protocol; it also providesa concise means by which an immediatereply can be requested at the top level ofthe end-to-end protocol. All end-to-endacknowledgements are carried in <replytail>s. A <reply head> can contain one ofthe words "rsvp" or "later"; the formerrequests an immediate reply, and the lattermerely informs the destination CIE that areply may be requested at some later time.

A <reply tail> also provides a means bywhich replies can be requested at a timeafter the original <message> was sent. Thispart of the <reply head> is much moreportentous than the previous paragraphindicates: when a CIE receives a messagewith a <reply head>, it must remembersufficient information to generate a replyupon a later request. Having sent a reply, itmust still hold the relevant informationagainst the reply's getting lost in the net. A<reply head>, then, means that the desti-nation CIE must keep a permanent recordof the <message> containing it! Clearly,that is too much to ask of any practicalcheap CIE; the remedy is to permit thedestination CIE to flush its records after anunspecified retention period, most likelyranging from a few milliseconds to a fewweeks. If it is asked to reply to a messageof which it has no memory, it can reply"unknown." Of course, end-to-end acknowl-edgement will be impractical for<message>ssent to a CIE with a very short retentionperiod, but that is a matter more properlyleft for a CIE's subscribers to work out withthe operators of their own and competingCIEs.

The <reply tail> also provides a meansfor replies to be sent from (or requested of)other levels in the end-to-end protocol; theoptional qualifier (such as "file") gives thatdetail. Thus, an unqualified positive reply(ie: "reply ok") to a mail message needn'tmean anything more than that the message

arrived at the CIE and was dispatched to theprogram that handles mail. A positivereply qualified as coming from the mail pro-gram (ie: "reply mail ok"), however, neces-sarily means that it was intelligible to themail program and that it was correctlyplaced in the proper mail file. The echo anddiscard verbs are included to provide amethod to detect and localize bugs in thegeneral framework of programs comprisinga CIE; for instance a "reply reply discard"message containing a <message ID> in its<reply head> will elicit a "reply ok" mes-sage from a CIE that exists and believesitself to have a reply program. If a "replyreply echo" doesn't elicit an echo, then thereply program itself could be malfunctioningin some basic way.

This flexibility allows the user to decidethe appropriate level at which replies shouldbe generated or whether they should begenerated at all. (Presumably the appropriateprograms will have user interfaces thatdon't turn the flexibility into a burden onthe user.) Two restrictions should be ob-served, however, to avoid loops. The first isquite intuitive: the reply to a "reply [xxx]echo" should be embedded in the appropriatetype of "reply [xxx] ok" message. Thesecond restriction is that all "reply [xxx]please" messages should refer to the originalmessage of concern; if a "reply reply please"message inadvertently gets sent that doesn'trefer to itself, then the receiving CIE shouldfeel free to discard it without comment.Also note that a "reply [xxx] echo" mes-sage is the only one that can elicit a replywithout itself containing a <message ID> ina<reply head>.

This completes the presentation of asketch of a design for the communicationsprotocols of a CIE Net. The BNF-like nota-tion of figures 1 to 5 defines the grammar ofthe message protocols; some more of the de-details of the design and its operation willprovide the substance of the third and finalpart of this series next month."

164

BYTE March 1978

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BYTE March 1978 165

Microchess 1.5 versus Dark Horse

Peter R Jennings27 Firstbrooke RdToronto, Ontario M4E 2L2CANADA

When the Second World Computer ChessChampionships were held in Toronto lastAugust (see January 1978 BYTE, page 108),the opportunity arose to challenge one ofthe best chess programs in the world to afriendly match against my microcomputer.A match was arranged between Microchessversion 1.5 and Dark Horse for the day afterthe tournament.

Dark Horse is a program written by UlfRathsman of Stockholm SWEDEN. It iswritten in FORTRAN IV and occupies 24 K

words of programmable memory with 60 bitwords on a CDC 6600 computer. On aver-age, it is capable of analyzing 12,000 posi-tions per move made. In addition, it utilizesits opponent's time by preparing replies toexpected moves. Although Dark Horse isconsidered to be a small program by classicalmainframe computer chess standards, itsstrategy is efficient and it finished in sixthplace at the World Computer Chess Cham-pionships.

Microchess is a program I wrote for the

White: Microchess

Black: Dark Horse

It was decided by a coin toss that Microchesswould play white. Since neither program makes useof an opening book, the opening is a little unor-thodox. However, by move 3 the position lookslike a normal opening.

1.

N-QB3

P-K3

2.

N-KB3

N-QB3

3.

P-K4

N-KB3

4.

P-K5

N-KN5

5.

P-Q4

P-Q4

6.

B-KN5

B-K2

7.

BxB

QxB

8.

B-K2

Q-N5

9.

R-QN1

0-0

10.

P-QR3

Q-K2

11.

0-0

P-QN3

12.

P-QR4

Q-N5

13.

P-KN3

B-N2

14.

B-N5

P-QR3

15.

N-QR2

Q-QR4

16.

BxN

BxB

17.

P-N3

P-QN4

18.

Q-K1

QxQ

19.

R(B1)xQ

PxP

20.

N-N4

PxP

21.

NxB

PxP

Dark Horse evaluates the pawns captured plus theresultant pawn on the seventh rank as more valu-able than the lost bishop.

22.

N-K2ch

K-R1

23.

R(N1)-B1

R(B1)-K1

24.

N-B6

K-N1

25.

RxP

P-QR4

26.

R(K1)-K2

P-R5

27.

N-N4

R(K1)-QB1

28.

R-N2

P-QB4

29.

N-Q3

P-R6

30.

R(I\I2)-Q2

PxP

31.

NxP

R-B5

32.

N-B4

P-R7

Dark Horse, which prints out the expected contin-uation, expected 33. RxP RxR, 34. RxR RxN, 35.R-K2, winning a knight for the pawn. It did notforesee 35. R-R8 (mate in one) because it trun-cated the analysis at 6 ply on this continuation. Asearch to 9 ply would be necessary to determinethe threat.

33. P-B3

Microchess did not take the pawn because it ex-pected the same continuation that Dark Horseprojected, with the loss of a knight. The threatof P-R8ch was not evaluated correctly due to abug in the program. This blunder resulted in a lossfor Microchess.

33.

P-R8 (Q)ch

34.

K-N2

NxP (K5)

35.

N-N3

Q-B6

36.

K-R3

RxN

37.

PxR

QxPch

38.

K-R4

Q-N5 Mate

Microchess took 47 minutes while Dark Horserequired only 11 minutes of processor time for thegame. Part of this difference is explained by DarkHorse's ability to compute responses on its oppo-nent's time.

Although Microchess was defeated by DarkHorse, it was not as one-sided a game as might beexpected given the difference in computing power.Further improvements in Microchess will probablybring it close to the playing level of Dark Horseand other programs in its class, but at a slowerspeed.

166

BYTE March 1978

Circle 48 on inquiry card.

DARK HORSE

MICROCHESS

Position after 32. ... P-R7.

KIM-1 in 1976. Commercial versions areavailable for the KIM-1, and a translatedversion is available for the 8080. Version 1.5is an extended version of the original pro-gram. It occupies 2.5 K of programmablememory and runs on a KIM-1 with expan-sion memory. Although it plays better chessthan the first version of Microchess, it isincomplete and requires further develop-ment.

Because of the complexity of chessanalysis, time becomes an important factorboth for micro and mainframe programs.One expected solution to the problem is theuse of multiple microprocessors to processportions of the analysis in parallel. Such adistributed network can reasonably beexpected to play as well as Chess 4.6, ifnot better, provided the heuristics used areequally powerful. I would not be surprisedto see this type of equipment in use at theThird World Computer Chess Champion-ships in 1980 to be held in Tokyo andMelbourne."

The following programs are available from Micro-Ware Ltd, 27 Firstbrooke Rd, Toronto, OntarioM4E 2L2 CANADA:

Microchess, A Chess Playing Program for the 6502processor. Price: $13.

Microchess, A Chess Playing Program for the 8080processor. Price: $18.

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BYTE March 1978

167

Take a Course

Richard Mac Millan19104 Alpenglow LnBrookville MD 20729

As is becoming the case for more andmore people, my job is bringing me intocontact with the quickly evolving field ofmicroprocessors and their applications. ThisI find fortunate because for several years Ihave had an intense interest in these gadgetsand their potential use in certain hobbyistapplications.

My employer and I agreed that it wouldbe useful for me to learn as much as possibleabout microcomputers in order to evaluatetheir future impact upon the transportationfield. (I'm an engineer in automotive elec-tronics.) To that end I started lookingaround for a seminar that I might attend.

One that caught my eye, a course givenby Wintek Inc, offered a "free" micro-computer to each participant. The 3 dayseminar that was being offered included adiscussion of microcomputer hardware andsoftware as well as hands on experiencein a laboratory. The program was based onthe 6800 processor family for illustrativeand training purposes.

Having signed up for the Wintek coursein advance, I presented myself at theappointed time and place (a meeting roomat a local Sheraton Inn). The Wintek pro-gram was presented by Dr Paul Wintz andJ im Wilson, the founders of the company.

Of the 35 participants, most were eitherengineers who, like myself, wanted tobroaden their knowledge of microcomputerprogramming, or they were professionalprogrammers looking to increase theirunderstanding of small systems applications.Several turned out to be computer hobbyistsas well. Most seemed to be lured to thisparticular course by the offer of a freemicrocomputer.

Material for the course was organized intoa large 3 ring binder which provides anexcellent reference after the course is con-cluded. The first morning (Tuesday) wespent learning our way around the 6800system. The bus structure was described insome detail as was the addressing of 10 andmemory. The 6800 instruction set wasintroduced as well as the various addressingmodes that may be applied to each instruc-tion.

in Microprogramming

Wintek has developed its own read onlymemory monitor program which it callsFANTOM II. FANTOM II is resident in a1 K read only memory on the 1 card com-puter Wintek gives its students, and issocketed so that it can be replaced witheither a 2704 or a 2708 if desired.

FANTOM's use was reviewed beforelunch on the first day. After lunch the classbroke into two groups with one going intothe first lab session and the other continuingin a lecture.

Lab consisted of a cluster of video ter-minals each connected to a Wintek 1 cardmicrocomputer. Students worked in pairson problems outlined in the course notes.An instructor was always available forassistance. The first afternoon in the labwas spent using the monitor program toload a simple routine into the computer andthen debug it.

At coffee break, the two groupsswitched: students coming out of thelecture took a turn at the lab work. The restof the course was spent alternately in thelab and in the class.

The Wednesday lecture discussed thevarious types of memories, their applicationsand trends to look for in the future. The 10devices of the 6800 family were alsocovered. The 6850 serial 10 port (really anintelligent UART style interface device)was presented both as hardware and interms of its use when programming tocommunicate with external equipment.The 6820 was then discussed. This deviceis a dual programmable 8 bit parallel 10port. Both the serial device and the paralleldevice interface directly with the 6800.Finally, time was spent learning the variousways that interrupts can be handled.

One of the best features of this coursewas the lab work. Working from simpleprograms to ones of more complexitywith the aid of an instructor helps tobuild confidence in oneself. My lab partnerand I worked our way through a programthat generated a time delay via a countdown loop, then used the loop as a basisfor a timekeeping function. The terminal'sbell function was used to mark the secondsand then the whole thing was integratedinto a program that performed a digitalclock function.

By the time Thursday rolled around wewere trying to service interrupts from thevideo terminal in the middle of the time-keeping program. For those with moreproficiency at machine language program-ming, there were more challenging projects,including a program to decode Morse code.

Lecture for Thursday turned to a com-parison of the various microprocessor

168

BYTE March 1978

Circle 108 on inquiry card.

families currently available. The advantagesand drawbacks of each were compared.The area of applications that each is bestsuited for was discussed. Software aidsto programming such as assemblers, editors,debuggers and compilers were explainedand their operations were illustrated.

While understandably Wintek's productsand services were mentioned at appropriateplaces throughout the course, no real hardsell was used. Their products were usedprimarily as an illustration of what is avail-able to the user and as such was a usefulpart of the curriculum.

The Wintek computer given to eachcourse participant consists of a 6800 pro-cessor, a 6820 peripheral interface adapter(PIA), a 6850 asynchronous communi-cations interface adapter (ACIA) (serialIO for communication with a Teletypeor RS-232 compatible terminal), two 6810128 by 8 random access memory chips,a 1 K read only memory containing Wintek'sFANTOM II monitor, a 600 kHz clock anda bps rate generator. Providing power(5 V, 12 V, -12 V), a reset button and aterminal is all that is required to be up andrunning.

Extra memory is available from Wintekbut it is dynamic, requiring an extra cardjust for the refresh circuitry. The hobbyistwould probably want to use a handful of2102s instead. Provision is made on theWintek card for two more memory chips,bringing the total read/write memory to512 by 8.

I mentioned at the beginning that severalof us in the class happened to be hobbyists.By the time we all had had a chance toactually work on the computers, most of uswho were at first uncommitted becameconverts. We left clutching our microcom-puters with thoughts of borrowing a ter-minal and writing our own programs.

Now, most hobbyists would hesitate tospend $500 of their own funds to attend acourse like this. That much money wouldbuy a lot of goodies or even a basic homesystem. Happily, many employers are willingto invest in such a program where there is alikelihood that the participant will bringstate of the art knowledge and very usefulexperience back to work.

People who, like myself, are looking for ageneralized survey of the current state ofthe art, in addition to some actual program-ming experience, might do well to seeka group such as Wintek in order to take acourse. While I may not have finished thecourse an expert microprogrammer, Icertainly have learned the basics necessaryto know where to start on nearly anymicroprocessor project."

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BYTE March 1978

169

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This article demonstrates how softwarecan be written to allow your computer to beused as an educational device. Having justgone through the exercise of helping mychildren learn all the states and their capi-

1 PRINTCHR$(26):PRINTCHR$(7):PRINTCHR$(7)

5 CLEAR 1000

10 DIM A$(50), B$(50)

20 FOR l=0TO49

30 READ A$(I).B$(I)

40 NEXT

50 PRINT "THIS PROGRAM Wl LL TEST YOUR KNOWLEDGE OF THE STATES AND"

60 PRINT "CAPITALS. AFTER EACH STATE (SELECTED AT RANDOM) PLEASE TYPE"

70 PRINT "IN THE APPROPRIATE CAPITAL FOLLOWED BY A 'RETURN' "

80 PRINT:PRINT

90 N=0:C=0:W=0

100 N=N+1: IF N> 10 THEN 400

105 l=49*RND(-1)

106 l = INT(l)108 QO

110 PRINT "WHAT IS THE CAPITAL OF ";A$(I);:INPUT Z$

120 IF Z$=B$(I) THEN 200

130 PRINT "NOT CORRECT!. . .TRY AGAIN":W=W+1

140Q=Q+1:IF Q>=2THEN 800

150 GOTO 110

200R=4*RND(-1)+1:C=C+1

201 R = INT(R)

210 IF R = 1 THEN 300

220 IF R=2THEN 301

230 IF R=3THEN 302

240 IF R=4THEN 303

250 PRINT "CORRECT.

300 PRINT "CORRECT.

301 PRINT "CORRECT.

302 PRINT "CORRECT.

303 PRINT "RIGHT ON!

.YOU'RE A GENIUS!!":GOTO 100.YOU'RE EXCEPTIONAL!!":GOTO 100.AMAZING ABILITY!!!":GOTO 100.YOU'RE TOO MUCH!":GOTO 100. .CARRY ON!":GOTO 100

400 PRINT "YOUR SCORE IS";C;"CORRECT";W;"WRONG";"RATING";C/(C+W)*100;

401 PRINT "%"

402 PRINT "DO YOU WISH TO CONTINUE THE LESSON (TYPE YES OR NO)?"

403 INPUT C$

404 IF C$ = "YES" THEN 90

405 IF C$= "NO" THEN 830

406 GOTO 402

600 DATA MASS.,BOSTON,MAINE,AUGUSTA,VERMONT,MONTPELIER

610 DATA NEVADA.CARSON CITY,NEW HAMPSHIRE,CONCORD,NEW YORK.ALBANY

620 DATA NEW JERSEY,TRENTON,CONN.,HARTFORD,VIRGINIA,RICHMOND

630 DATA W.VIRGINIA,CHARLESTON,MARYLAND,ANNAPOLIS,N.CAROLINA,RALEIGH

640 DATA S.CAROLINA.COLUMBIA,FLORIDA,TALLAHASSEE,GEORGIA.ATLANTA

650 DATA ALABAMA,MONTGOMERY,ARKANSAS,LITTLE ROCK,MISS.,JACKSON

660 DATA WASHINGTON,OLYMPIA,N.MEXICO,SANTA FE,N.DAKOTA,BISMARCK

670 DATA S.DAKOTA,PIERRE,IDAHO,BOISE,ILLINOIS,SPRINGFIELD

680 DATA OHIO,COLUMBUS,INDIANA,INDIANAPOLIS,IOWA,DES MOINES

690 DATA KANSAS,TOPEKA,MISSOURI,JEFFERSON CITY,OKLAHOMA

700 DATA OKLAHOMA CITY,COLORADO,DENVER,UTAH,SALT LAKE CITY

710 DATA HAWAII,HONOLULU,ALASKA,JUNEAU,TEXAS,AUSTIN,LOUISIANA

720 DATA BATON ROUGE,PENN.,HARRISBURG,RHODE ISLAND,PROVIDENCE

730 DATA WISCONSIN,MADISON,MINN.(ABBREV.),ST. PAUL,MICHIGAN,LANSING

740 DATA KENTUCKY,FRANKFORT,TENNESSEE,NASHVILLE,NEBRASKA,LINCOLN

750 DATA MONTANA,HELENA,WYOMING,CHEYENNE

760 DATA DELAWARE,DOVER

770 DATA CALIFORNIA,SACRAMENTO,OREGON,SALEM

780 DATA ARIZONA.PHOENIX

800 PRINT:PRINT:PRINT "WELL, I GUESS YOU REALLY DON'T KNOW IT!! (SHAME)"

810 PRINT "THE CORRECT ANSWER IS ' ";B$(D;" ' NOW I WILL ASK YOU AGAIN.!"

820 GOTO 108

830 END

170

BYTE March 1978

Circle 111 on inquiry card.

Circle 8 on inquiry card.

Ppogpsmming Guickies

tals, it occurred to me that this might bereadily automated using a computer andBASIC.

The program in the listing is written torun in MITS 8 K BASIC in about 3 K bytesof memory. It easily fits into my Altairsystem which has 12 l< bytes of memory.

All the states and their capitals are listedin the DATA statements beginning on line600. The arrays A$ (I) and B$ (I) are initial-ized with the BASIC READ statement em-bedded in a FOR. . .NEXT loop at lines 20to 40. As you can see by the logic, eachstate and its corresponding capital are listedas a pair of strings in the DATA statements.As the variable I goes from 0 to 49 the firststate name will be in A$ (0) and the capitalof the first state will go into B$ (0); the nthstate name will go into A$ (n) and the ntnstate capital will go into B$ (n).

In operation, the program is a loop whichkeeps generating random state selectionsand quizzing the student. A number Ibetween 0 and 49 is chosen at random inline 105 using the RND function, whichreturns a value from 0 to I. The corres-ponding state A$ (I) is selected and thequestion is generated. The student answerswith an input which is stored in Z$. If theinput from the student in Z$ is equal to thecapital B$ (I) of the selected state theprogram will execute the "reward" subrou-tines. If the answer is not correct, then thequestion is repeated one time. If the correctanswer is not given the second time, thecomputer then provides the correct answerand repeats the question in order to aid inthe learning process. If the correct answeris given, the student is rewarded with apositive response, such as "Right on; carryon" or "You're exceptional." This responseis also selected using a random numbergenerator in order to provide a bit ofvariability in the reward statement. Afterten states and capitals are provided, the com-puter gives a score summary with a percentevaluation of the student's responses.

The above programming concept can beapplied to almost any teaching situationwhere an answer word or phrase can bedirectly associated with a question. Thequestions and answers are convenientlystored in the data lines within the programand are separated only by commas.

We have had fun making up this programand managed to learn a few of the statesand their capitals in spite of it all!"

••••••+++***••••••••••••••••*

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WITH SOFTWARE WRITTEN

IN NORTHSTAR BASIC

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ADDITIONAL PROGRAMS NOW IN PROGRESS -PLEASE WRITE FOR FURTHER INFORMA TION.

fr wJ^^E ^P^E3E^%^fc3fc3fc3%J%JtJfrJ^JE3^^%3E3^3EJE3frJwJ%3fc3w^^^E3fc|3>3BMfc^*ME3>^%'^ j

PRAMMER III

by

xybek

The Ultimate EPROM Memory BoardFor Your S100-Bus Computer

* Accommodates from 1 k to 30k of the above EPROMS, in

any combination, each addressable on any 1k (2k for2716) boundary within the board's 32k address space.

* 1k of scratch-pad RAM.

* On-board programming for all three EPROM types.

* Tri-state buffers on all address and data lines.

* Empty EPROM sockets do not require address space.

* Assembled, tested, ready to run — only $369.50

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Telephone: (408) 296-8188

§gagQg3BPOgS3gnqag)pa8jqeSSg83at^^

Circle 138 on inquiry card.

BYTE March 1978

171

Conducted byDavid Wozmak

Globs andNewsletters

Philadelphia Area Computer Society

The Philadelphia Area Computer Societywas formed to educate computer users in thePhiladelphia area and to inform the generalpublic about computer technology and itsimplications -for the future. Membership isopen to all persons interested in any aspectsof the computer arts and sciences.

Dues are $10 for regular membership and$5 for students. Both include a subscriptionto The Data Bus as well as participation ingroup purchase programs and club projects.Members also receive borrowing privilegesin the Society's software and literaturelibrary.

PACS meetings are held in the LaSalleCollege Science Building at the corner of

pDR. DOBBS - INTERFACE AGE - BYTE - POPULAR ELECTRONICS - ROM - KILOBAUD^t=> -a

i ARTICLE

O

o

INDEX\

o

PERIODICAL

■

1

13

GUIDE

MAKE FULL 1

—i

oo

FOR

USE OF sj

1

COMPUTERISTS

MAGAZINES ?

oa:o

1977

o

T INI

JEX OF PERSONA L C

OMPUTING ARTICLES .

o

Letters from Readers * Book Reviews £

a:

1

Articles *Editoria]s'Indexed by Subject £

o

7977 Jan Dec 25 Magazines Indexed

1

o

1975 1976 15 Magazines Indexed 1

1 *5

each Postpaid Money Back Guarantee 3

E.BERG PUBLICATIONS s

CD

g

1360 SW 199th Ct; Aloha, OR. 97005 5

SEND FOR BROCHURE 1

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RONICS - RADIO ELECTRONICS - PERS

ONAL COMPUTING -CREATIVE COMPUTING J

20th and Olney (12 blocks north of US 1 onBroad St). Write to PACS, POB 1954, Phila-delphia PA 19105.

NCCS

The Northwest Computer Society meetsat the Pacific Science Center in Seattle onthe first and third Wednesday of each monthat 7:30 PM. The first meeting of the monthis usually formal, involving a featuredspeaker or a demonstration. The secondmeeting of the month is usually moreinformal, with discussion and problem solv-ing. The group also publishes a newsletter,Northwest Computer Club News.

Call Roy Gillette at 524-0596 (evenings)for more information, or write NorthwestComputer Club, POB 242, Renton WA98055.

The New York Amateur Computer Club

The New York Amateur Computer Clubis a group of people with varying back-grounds, abilities, and interests whose com-mon goal is "to promote the free exchangeof information about computers for personaluse, and to encourage fellowship amongthose interested in computing."

Club dues are $10 annually, from July 1thru June 30, or $5 if you join after January1. Prospective members are sent one or twoissues of The Newsletter free of charge andare encouraged to attend club meetings asguests. For more information, contact TheNew York Amateur Computer Club, ChurchSt Station, POB 106, New York NY 10007.

Association of Computer Experimenters

This group, located in Hamilton, Ontario,puts together a huge newsletter, IPSOFACTO, which has all kinds of information.The last issue I saw had several articles oncassette interfacing, including the KansasCity Standard, Data Formatting, etc. Formore information, contact Tom Crawford at50 Brentwood Dr, Stoney Creek, OntarioCANADA L8G 2W8.

Central Florida Computer Club

The Central Florida Computer Club hasbeen in existence for over a year and hasover 50 members. You can contact them bywriting to John W Neel, 2821 Sunset Rd,ApopkaFL 32703.

NCCCCC (NC5)

On May 5 and 6 the Northern CaliforniaCommunity College Computing Consortium(whew) Spring Conference will be held atSierra College, 5000 Rocklin Rd, Rocklin

172

BYTE March 1978

Circle 9 on inquiry card.

Circle 38 on inquiry card.

CA 75677. Contact Perry Edwards at (916)624-3333 for details, or write to him at theabove address.

65 Notes

65 Notes is the monthly publication ofthe HP-65 users club. It contains mainly pro-gramming twists and information concerningthe HP-65. Also included are programs andclub information. Contact Richard J Nelson,2541 W Camden PI, Santa Ana CA 92704.

San Diego Computer Society

This group publishes a well put togethernewsletter, Personal Systems. It containsclub information, programs and so on.

The San Diego based club has specialinterest groups on the Z-80, 6800 and 1802,6502, 8080, as well as groups on biofeed-back, education, graphics, and word process-ing in the legal profession. The address is SanDiego Computer Society, POB 9988, SanDiego CA 92109.

The Computerist

This newsletter, edited by Mark Browneand Geoff Wattles, covers four differentclubs: The Minnesota Computer Society(MCS); Small Computer Engineering Associ-ation of Minnesota (SCEAM); UniversityMicrocomputerGroup (UMG); and AdvancedTechnology Research Association (ATRA).

The newsletter contains information con-cerningall the clubs, including meeting dates.The March dates are as follows: SCEAM:March 30; UMG: March 1, 8, 15, and 22;MCS: March 5; ATRA: March 7, 14, 21, 28.

For more information concerning theclubs, write to Mark Browne, 3504 StevensAvS, Minneapolis MN 55408.

Homebrew Computer Club

The Homebrew Computer Club meetsregularly at the Stanford Linear AcceleratorCenter Auditorium (SLAC). During the pasttwo years, attendance has increased fromthirty people to over two hundred. TheHomebrew Computer Club, which also pub-lishes a newsletter, can be reached at POB626, Mountainview CA 94042.

West Virginia Computer Society

Oscillations is the name of the WestVirginia Computer Society's newsletter,which features short articles about newmicroprocessor developments, video games,local computer news, and so on. For infor-mation on the time and location of localmeetings, contact Bill England at WVCS,167 Iroquois Trail, Ona WV 25545."

>

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Kit with all but2114 memories $88

Bl ANK BOARD $35

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S-100 EXTENDER BOARD $16

With jumpers in power supply lines lor current measurements. Low profileso card can remain in the machine with cover on. Wide edge connector.

PRICES SHOWN INCLUDE U.S. SHIPPING. WE ACCEPT VISA, MASTER CHARGE,CASHIERS CHECK, MO. ALLOW TIME FOR PERSONAL CHECKS TO CLEAR. COD.ORDERS ADD $]. UTAH RESIDENTS ADD 4K* TAX.

Digital KIjcbd Systems

V

BOX 1212, OREMr UTAH 84057(801) 224-2102

ED SMITH'S SOFTWARE WORKS

Announces A

M6800 SYSTEM RELOCATING ASSEMBLER

AND LINKING LOADER

for SwTPCo or Altair 680b

ATTENTION ALL NON DISC 6800 OWNERS: Now you can produce large object pro-grams without the restriction of requiring enough memory storage to contain the textneeded for large size object programs. By using our Relocating Assembler and LinkingLoader you create your programs in smaller, more easily handled segments which can beassembled separately and then linked together at load-time. This, in effect, allows as-sembly of programs whose object code alone would require most of your systemmemory. Load-time linking also provides the capability of setting up program librarieswhich can be called by any program without having to include the text in each assembly.This assembler has many features new to the personal computing market, such as relo-catable code, a full alphabetized cross reference listing, both local and global labels,listing of execution time, 8 character labels, use of a break character in labels, variablecolumn print and terminal listing formats, and for all those PR-40 forty column printersout there the ability to produce an 80 column professional looking assembly outputlisting. The assembler also includes a mini-editor to allow coresident correction of as-sembly errors, load and save source code, generate new source code, list source code,etc. The source code uses the TSC Text Editor format so that their program may be usedto compliment and expand the included editing functions.

The Relocating Assembler and the Linking Loader are furnished on cassette in relocat-able formatted code, so they may be placed anywhere in memory. A short mini-loaderprogram in standard Mikbug format is supplied to initially load the Linking Loader atany desired address. A comprehensive Instruction Manual and an extensively commentedassembly listing complete the M68AS assembler package.

M68AS $50.00

A disc oriented version of the Relocating Assembler and Linking Loader is also availablefrom Smoke Signal Broadcasting.

Other Programs (see Dec. Byte)

M6800 Disassembler/Trace M68DT $20.00

M6800 Source Generator M68SG 25.00

M6800 Relocate M68RL 10.00

M6800 Binary Loader M68BL 10.00

Package of above 4 programs M68PK 55.00

Order direct by check. Specify system configuration if other than SwTPCo. Californiaresidents add 6% sales tax.

Note: We shortened our address:

Ed Smith's

SOFTWARE WDRHS

P. O. Box 339Redondo Beach, CA 90277

Circle 105 on inquiry card.

BYTE March 1978

173

Controlling the Real World

Hank Olson

POB 339

Menlo Park CA 94025

For many experimenters, the micro-processor is an excellent source of mindstimulation, and that is a laudable end initself. But after you figure out how a com-puter works, perhaps build one, and playvarious games with it, you might want to tryyour hand at process control.

FROM , ,.

output r_>

PORT

Figure I: Simple half wave control of AC operated devices using an SCR(silicon controlled rectifier) optocoupler.

15 w

LIGHT BULB

FROM ,

0UTPUTf_J>PORT

BR 1

MOTOROLA

HEP-R0803

Figure 2: Full wave control of AC operated devices using an SCRoptocoupler.

Industry looks upon the microprocessoras the controller of processes, whether aslarge as a steel rolling mill or as small as atelephone instrument. And, indeed, themicroprocessor may be one way to helpsolve the automobile emission problem,the fuel crisis in home heating, and a myriadof other current social problems.

The output of an appropriate set of onesand zeros by the microcomputer (after it hasdigested all its inputs and instructions) is allthat is required to solve the problem,theoretically. However, there still remains afair gap between the microcomputer outputand the closure of a solenoid valve in a pieceof machinery, for instance.

Figure 1 shows one such real worldapplication, an SCR (silicon controlledrectifier) optocoupler used to control a 117VAC line operated device with microcom-puter output logic voltages. This circuitwill certainly work, but the light bulb loadwill light only to half brilliance because theSCR conducts only on the positive half cycleof the AC line voltage. One way of gettingaround this is to modify the circuit, asshown in figure 2, by using a diode bridgein conjunction with the SCR photocoupler.This is an old trick developed to allow SCRsto be used for full-wave control. It cameinto use before the introduction of theTriac.

There is another way of achieving fullwave AC control: Use a dual SCR opto-coupler such as the Monsanto MCS6200.Since there are two light emitting diodes andtwo photo-SCRs (each LED controls its ownphoto SCR), one can connect the LEDs inseries and the photo SCRs in reverse parallelto create the equivalent of a Triac photo-coupler. This connection is shown in figure3. (The MCS6200 is useful for other applica-tions, of course, such as polarity reversal.)

174 BYTE March 1978

FROM ^^OUTPUT l>PORT

I20VAC

Figure 3: Using a dual SCRoptoisolator for full wavecontrol of an AC operateddevice.

The MCS-1 and MCS6200 are ratherlimited in their current handling capability,however. The MCS-1 will carry 250 mA andthe MCS6200 will carry only 150 mA. Thissort of capability is fine for lighting smalllight bulbs, but hardly suitable for the typesof loads found in real process controls.

When working with 117 VAC controlschemes, zero voltage turn on and zerocurrent turn off are desirable design goals.If we had a logic controlled device capableof closing the AC connections only when theAC voltage is crossing through zero, a num-ber of problems would be solved. (AC volt-age alternates sinusoidally, crossing the zerovoltage point twice per cycle.) The largeinrush current that can occur when an ACswitch is closed at (or near) the positive ornegative peak of the AC sine wave can beeliminated by such a zero voltage turn ondevice. Zero current turn off techniqueshave the added advantage of not interruptinglarge currents in mid flow. If the AC loadis a pure resistance such as a light bulb or

heater, the zero voltage and zero currentpoints are coincident in time; but, in general,AC loads will have inductive or capacitivereactance. The current and voltage wave-forms will therefore be not quite in phase.For general use, we wish our logic con-trolled AC switch to have both zero voltageturn on and zero current turn off. Sucha device is the modern solid state relay.

The Monsanto MSR100B is a goodexample of the solid state relay. As withother optically coupled devices, the solidstate relay maintains complete isolationfrom the logic level controlling system. TheMSR100B is shown in block diagram form infigure 4. The device is rated for 10 A at 120VAC. So up to 1.2 kW can be controlledwith only TTL level inputs. The modernsolid state relay has a myriad of protectivefeatures built into it (see figure 4). The zerovoltage turn on and zero current turn offfeatures contribute most to the desirabilityof the solid state relay since they can atten-uate line transients and radio frequency

CONTROLVOLTAGE

V(-)

V(+)

INPUT

BUFFER

FILTER

T"

'~l

*'CI

OPTICALISOLATOR

Figure 4: A typical solid state relay. Units such as this Monsanto MSR J00/200 have many con-venient features. The zero voltage and zero current switching abilities eliminate damaging highcurrent surges to the load, as well as high voltage transients experienced with inductive loads.The input filter prevents short duration noise (<10 ps) of signal strength from falsely switchingthe relay. The output filter suppresses transient signals generated either from inductive loads orlong lines.

BYTE March 1978

175

H5VA

Figure 5: Use of anoptocoupler to directlycontrol a relatively smallload.

FROM

OUTPUT EX-PORT -. r

IC COLLECTORCURRENT INDETECTOR(mA) 15

jFsAOrt^.

|F = 20mA_

IF=IOmA

5 10 15 20 25

DETECTOR VCE COLLECTOR VOLTAGE (VOLTS)

Figure 6: Monsanto MCT-I solid state relay characteristics for various LEDcurrents.

ECCA

+ 5VA

r"

Figure 7: Use of anexternal NPN transistor toincrease load current con-trol capabilities.

JT

FROM

OUTPUT I ~>PORT

I

J~L

&V

_J

rn

interference that could get back into theprocessor and unload memories or modifyprograms. Solid state relays are made byInternational Rectifier Corp (Crydom),Amphenol (Runker Ramo), C P Clare,Douglas Randall (Kidde), Electrol, Gordos,Gould (Allied Control), Gray hill, HeinemanElectric, Potter and Brumfield, Teledyne,and Theta-J, to name a few. It is a good ideato study the features of the various relaysavailable, since there are so many variations.10 A is a common current rating, but unitsare available with up to 40 A currentcapacity.

We next consider the DC side of things.Where is DC used for these types of applica-tions? The automobile is one answer. Theauto industry hopes to use microprocessors,but must operate them from +12 VDC forreasons of practicality. The SCR opto-coupler in figure 1 can not be used for DCcontrol, unless one wishes the DC beingcontrolled to latch "on." That is, once thecontrolling diode turns the photo SCR "on"(with a DC supply of the proper polarity),the SCR will stay on no matter what thecontrol current does. In order to controlDC, it is a better plan to use a more con-ventional optocoupler, ie: one that has aphototransistor as the output device. Suchoptocouplers are widely available from mostof the semiconductor producers. Among theproducers of optocouplers are Fairchild,Hewlett-Packard, Litronix, Monsanto,Motorola, and Texas Instruments.

An example of the use of optocouplersfor isolated DC control is shown in figure 5.A Monsanto MCT-1 is used in this circuit,which has a characteristic like that shownin figure 6. The MCT-1 is an early opto-coupler, and it has a rather low ratio ofcollector output current to photo diodeinput current (about 35%). Newer opto-couplers, using photo Darlington transistors,can have a ratio of 500% or more. That is,for an optocoupler with a 500% currenttransfer ratio, 10 mA of control diodecurrent will cause 50 mA of current to flowin the collector of the output (Darlington)photo transistor.

Most optocouplers are restricted to out-put currents of 100 mA or less with phototransistor voltage ratings of 30 V or less.(There are exceptions, like the MonsantoMCA2200, which will stand 200 V.) Acapability of 30 V and 100 mA means thatoptocouplers can handle relatively smallloads of only a few watts. This is not aproblem, since the optocoupler can be

176

BYTE March 1978

followed by a power transistor whosecurrent gain, voltage rating, and currentrating can increase the capability to con-trol hundreds of watts. Three ways thatthis can be done are shown in figures 7,8 and 9. Note that using an external tran-sistor to increase voltage or current cap-ability may cause an inversion of the logic,but this can be easily corrected either insoftware or by the addition of a single 7405inverter section on the logic side of theoptocoupler.

Many devices used in process control haveinductive reactance as part of their imped-ance. As a result, when switching relays,solenoids or motors with transistors(whether directly from the photo transistorof the optocoupler or by means of an exter-nal transistor) it is desirable to add "induc-tive kick" protection. The inductive kickoccurs when the transistor attempts to turnoff the inductive load. At this point, thecollector voltage can easily exceed the maxi-mum rating. A diode across the inductiveload will protect the transistor as shown infigure 10.

Another method of protection is the useof a thyrite varistor as in figure 11. Thethyrite varistor must be chosen so as to drawreasonable current when the normal coilvoltage is present across it; thyrite varistorsare nonlinear resistors and draw abnormallyhigh current when the voltage across themincreases (during the inductive kick).

For general reference on the subject ofthe various optically isolated couplers dis-cussed here, references 3, 4, and 5 arerecommended. The catalogs of such pro-ducers as Monsanto are also useful; briefapplication data often accompany the datasheets."

REFERENCES

I

_n_

FROM

outputO-1

PORT

rh

150V

~LT

+ ECC

Figure 8: Using an ex-ternal PNP transistor toincrease the load currentcapability. This circuit isuseful when the load musthave one side commonto the control systemground.

Figure 9: Use of a highvoltage NPN transistor todrive a load requiring highDC voltages.

FROM

OUTPUT OPORT

INDUCTIVELOAD

1. General Electric, Silicon Controlled RectifierHobby Manual, 640.8, pages 31 thru 34,1963.

Figure 10: Using a diode to protect the drive transistor from an inductivekick voltage overload.

2. Smith, G, "Applications of Opto-lsolators,"Lightronix Appnote 2, Litronix Inc. 19000Homestead Rd, Vallco Park, Cupertino CA95014.

3. Hewlett-Packard, "Optoelectronic ApplicationsSeminar (Notes)," 592-0343, Hewlett-Packard,1501 Page Mill Rd, Palo Alto CA 94304,1972/1973.

4. Christian, F, "Isolation Techniques UsingOptical Couplers," Motorola Application NoteAN 571, Motorola Semiconductor, POB 20912,Phoenix AZ 85036, April 1973.

FROMOUTPUT \~>PORT

+ ECC 2

INDUCTIVELOAD

/77

5. Mazur, T, "Four Terminal, Optically-IsolatedZero-Crossing AC Relay," MotorolaApplication Note AN 598, March 1973.

Figure II: A circuit which uses a thyrite varistor to protect the drivertransistor from an inductive kick voltage overload.

BYTE March 1978

177

Interfacing the Sykes OEM Floppy

Phil Hughes

POB 2847

Olympia WA 98507

This article shows how I interfaced aSykes 7158 OEM floppy disk kit to aSwTPC MP-68 computer system. The systempresented is not the ultimate design but it

Photo I: The interface between the Southwest Technical Products 6800system and the Sykes floppy disk subsystem was fabricated on this proto-typing board for the SwTPC bus. The schematic is shown in figure 3.

has been built and it operates properly. Iconsider it a good basis for the develop-ment of a disk operating system.

First, let's look at the Sykes kit. The7158 kit consists of an Orbis disk drive anda controller designed and built by Sykeswhich employs a 6502 microprocessor.This is one of the smarter controllers. Theinterface consists of only an 8 bit bidirec-tional bus and five control lines for hardwarerequirements. Software commands such astrack select, read sector X and reset are used.Additional commands such as step head inand step head out are available but are onlyused for diagnostic purposes. Cost of the7158 kit is about $1300.

Alternatives to the 7158 kit are the 7258,7358, and 7458 kits which are similar butinclude two, three or four disk drives. Noticethat the controller can handle up to fourdisk drives. Another alternative is the 9158and its multiple drive relatives 9258, 9358and 9458. These units offer greater packingdensity and therefore greater storage capac-ity. The capacity of a 7000 series drive is256,256 bytes and 630,784 bytes for the9000 series. If you need the extra capacity a9000 series kit may be a better choice. How-ever, this is Sykes' own format and is notlikely to be compatible with anything else.The 7000 series units are compatible withthe IBM 3741 format.

If you are unfamiliar with the IBM floppydisk format it is composed of 77 tracksnumbered 0 through 76. Each track isdivided into 26 sectors numbered 1 thru 26.Each sector consists of four fields as shownin figure 1.

Power requirements for the disk and con-troller are shown in table 1. A commercialpower supply can be purchased or you canbuild your own supply. Figure 2 is aschematic of a power supply which suppliesthe needed voltages, offers voltage adjust-ment on the +24 and +5 supplies and hasboth adjustable current limiting and over-voltage protection on the 5 V supply.

Once the power requirements are satisfiedwe can get to the interface. My design goalhere was to build the complete interface ona circuit board which would fit into an IOslot on the MP-68. This feat is shown inphoto 1. This interface was built on aPersonal Computing Company board usingquasi wire wrap techniques. This means that

178

BYTE March 1978

Disk Kit to a Personal Computer

Photo 2a. Top view of theOrbis disk drive used bySykes in its 7158 system,with the floppy diskinserted.

Photo 2b: Bottom view ofthe Orbis disk drive usedby Sykes, showing thebuilt in control electronicsand belt drive for the diskspindle. The Sykes inter-face (photo 3) has beenremoved for this picture.

BYTE March 1978 179

Photo 3: The Sykes floppydisk controller board. Thisboard mounts on thebottom of the Orbis drive;it contains a 6502 proces-sor with read onlymemory programmingneeded to implement thehigh level commandsequences available on thebidirectional interface.

all the ICs were placed in wire wrap socketsand all other connections were soldered. Ifound this to be a very workablecompromise.

The schematic of the interface is shownin figure 3. The heart of the interface is a6820 Peripheral Interface Adapter (PIA).Support components are needed to inter-face to the disk controller bus. Also I builtfour level indicators and permanently con-nected them to TP1 thru TP4. These in-dicators proved very helpful during bothhardware and software debugging.

AM ID Field DM Data Field

Voltage

Controller

Drive

Total

+24 ± 10%

1.5 A max.75 A idle

1.5 A

-12 ±10%

100mA

100 mA

+5 ± 5%

3.0 A

.75 A

3.75 A

Table I: Disk interface DC power requirements. The power supply of figure 2was designed and built to meet these requirements; for those desiring to omitthis detail, Sykes makes available a power supply module for the controllerand drive.

AM = Address mark. Indicates that an ID fieldfollows immedately.

ID Field = Identifies track and sector number ofthe following record.

DM = Data mark or delete mark. A data markdelimits the ID field and indicates that a goodrecord follows. A delete mark delimits the IDfield and indicates that a deleted record follows.Note that the deleted record flag is a softwarefunction. A read of a deleted record is processed;just the status is set to indicate that the deletedrecord flag was set.

Data Field = Contains 128 bytes of data. If lessthan 128 bytes are transferred the record is filledby the controller. Note that both the ID field andthe data field are terminated by two cyclicredundancy check (CRC) bytes. These charactersare automatically generated and checked by thedisk controller.

Figure I: Sector layout. The sector layout isfixed by the design of the controller. Eachsector has 128 bytes of data, and an identi-fication number which contains track andsector information in the "soft" format forfloppies.

180

BYTE March 1978

MAINPOWER

II5VAC SWITCH

50 PIV

ioa 777

t2 stancor pca-4

34 vac, center tapped © .35a

19 vac, center tapped © 2.5a

Miscellaneous hardware required

2 fuse holders

Line cord and switch

Chassis

Power terminal strip

Heat sinks (4) for power semiconductors

CURRENTLIMITER 777

Figure 2: Power supply for disk system. This power supply uses the 723 voltage regulator IC to actively regulate a 24 V 2 Asupply for the disk motor(s), and electronics supplies of -12 Vat 0.35 A and 5 Vat 4 A.

The software which I have developed isreasonably primitive but should be a valu-able tool for use in the development of adisk operating system. It performs fourfunctions. They are read (R), write (W), exit(X) and start (S). The read and write func-tions transfer the first 8 K bytes of memoryto and from specified locations on the disk.The user is prompted for the location whichis indicated by one character from A to P.This character is converted to a track addressand the 10 function is performed. After eachoperation the disk status byte is returned tothe control terminal. The exit functionreturns control to the Motorola MIKBUGmonitor. The start function performs a \MPto location 0100, the start address of theSwTPC software.

Hexadecimal

Condition

Va

ue of Bit

Bit Position

Deleted Record

80

Bit 7

Fault

40

Bit 6

Track 00

20

Bit 5

Disk Protect

10

Bit 4

CRC Error

08

Bit 3

Busy

04

Bit 2

Ready

02

Bit 1

Data Service

01

BitO

Table 2: Controller status byte. Each bit ofthis byte determines one flag signal sentback to the computer. Detailed informationis included in the Users Manual For Series7000/9000 OEM Systems Kit which issupplied with the drive when it is purchased.

BYTE March 1978

181

SWTPC 40 PIN10 BUS

RESETRSO

+ 8V UNREG. [3>

E|> RESET

'NORMAL" 6800TERMINOLOGY I SYKES

| TERMINOLOGY

6ND PINS 1,10,11,12.13,15,17,19.21.23,24

LEVEL INDICATOR

Figure 3: Southwest Tech-nical Products 6800 com-puter interface card designfor the Sykes floppy diskkit. A 6820 PIA partdetermines the state of thevarious interface lines andeffects the transfers.

Power Connections

IC

Type

+5

Gnd

IC1

6820

20

1

IC2

8835

16

1

IC3

8835

16

8

IC4

8T97

16

1,8,15

IC5

7400

14

7

Using these basic functions, programssuch as the Editor, Assembler, and BASICcan be loaded into memory and written outto disk so that they can be subsequentlyloaded from disk. The advantage: It takesabout 30 seconds to load the disk loadroutine from cassette at 30 cps and thendisk IO is performed at about 10,000 bytesper second. If you modify the Editor,Assembler, and BASIC so that they do notuse the memory where DISKLD is locatedyou will be able to load each programdirectly from disk.

For example, the following sequencecan be used to modify 8 K BASIC so that it

will preserve the memory used by the diskload routine and save 8 K BASIC on disk.

• Load 8 K BASIC from cassette or paper

tape.

• Change memory location 0044-0045 to

hexadecimal 2DFF. This is the uppermemory limit that BASIC will attemptto use.

• Load DISKLD from cassette or paper tape

and start.

• DISKLD should respond with "22LDR>."

The 22 is the status as defined intable 2. If the status is other than 22or 02 you should look it up in table 2and determine what the problem is.

• In response to "LDR>" enter "W" (for

write).

• In response to "ID—" enter the ID you

wish to save BASIC under. (B is alogical choice.)

• DISKLD should respond with the status

again (which should be 02) followedby another status and the "LDR>"message.

182

BYTE -larch 1978

If the status is correct from the previoussequence you should now be able to loadBASIC from the disk and start its executionby the following sequence.

• If the system has been powered down or

DISKLD is not loaded, load it fromtape and start.

• If the status is correct enter "R" for read.

• In response to "ID—" enter the ID of

BASIC ("B").

• If the status is correct enter "S" to start

execution.

For those who wish to dig in and startwriting some fancy software DISKLD con-tains the following functional units.

• DCNTRL - Calls the PIA initialization

routine, prompts the user for thedesired function (R, W, X or S) andtransfers control to the requestedroutine.

• DINIT-SetsupthePIA.

• DCOMM — Issues the command in the A

accumulator to the disk and returnsdisk status in the A accumulator andPIA address in the index register (X).

• DIPLR - Prompts for ID and performs an

8 K byte disk read.

• DIPLW — Prompts for ID and performs an

8 K byte disk write.

• DTERM — Issues a terminate command to

the disk controller, returns the statusto the control interface and returnscontrol to DCNTRL Used by DIPLRand DIPLW.

• DISKLD-Designed to work with MIK-

BUG and with the disk interfaceconnected to 10 slot 0. The EQUs atthe beginning of the program set upthis environment and can be changedto meet the requirements of differentconfigurations.

The hardware interface requirements aredefined in detail in the documentationsupplied with the disk kit. These basicsshould make the SwTPC interface moreunderstandable:

• D1 to D8 are eight bidirectional data

lines. Their direction and contents aredefined by the status of the DOT andDATA control lines. Note that Sykesdefined the high order bit as D1 andthe low order bit as D8. (Motorola andSwTPC define D7 as the high order bitand DO as the low order bit.)

• RESET is a bidirectional, ground asserted

signal. The interface is designed so that

Listing 1: Software of the primitive diskinterface software used to test out the driveand provide a minimum level of mass storagefunction. DSKLD performs four functions:

R = read a block from disk.W = write a block to disk.X = exit the DSKLD program.S = start a program at the assumed entrypoint of hexadecimal 100.

This program was assembled and listed usinga printer with narrow width, so commentsare somewhat restricted. The terminalcommand interpretation is done by meansof a sequence of comparisons at addresses2E14 to 2E22.

only the processor can send a resetcommand to the disk controller.

• FLAG is a controller originated, ground

asserted signal. This signal informsthe computer that the disk controllerrequires service.

• DATA is a computer originated, ground

asserted signal. When asserted, the datalines (Dl thru D8) will contain a databyte. When not asserted, the data lineswill contain either a command (fromthe computer) or a status (from thedisk controller).

• DOT is a computer originated, ground

asserted signal. When asserted it in-dicates that the direction of transferon the data lines is from the computerto the disk.

• STROBE is a computer generated, ground

asserted signal indicating that informa-tion is being transferred on the datalines.

Section A of the PIA is used to handlethe data lines. The peripheral control lineCA2 is used to supply strobe information.The two low order bits of section B of thePIA are used to control the DOT and DATAcontrol lines. Bit 7 of the B section of thePIA is used to receive flag information fromthe disk controller. Initially CA1 (PIAsection A interrupt input) was to be usedfor the flag function; however, the currentdesign of the DISKLD program can loose aflag status change. Using PB7 has proved tobe easier to handle.

For those who wish to develop a diskoperating system from the basic hardwareand software I have the followingsuggestions. The easiest type of disk alloca-tion system to handle and integrate into

NAM

DISKLD

OPT

0

OPT

NOP

OPT

S

DFT

NOG

* SUFER SIMPLE DISK

E6E3

HIKBUG ECIU

JESE3

E37E

PDRTM EQU

JE87E

EMC

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JElfiC

E1D1

OUTEEE EQU

JE1D1

EBBF

0UT2H EQU

IE86F

8080

DPIfi EQU

*888G

2E89 ORG 32E08

2E88 OCNTPL EQU •

2E8n S) 2E38 JSR DINIT

2El'C, 66 88 LDfl A #188

2E05 BD 2E4?

JSR

DCOMM

2E88 BD EOBF

JSR

0UT2H

PRIN

T STATUS

2E8B CE 2E33

LDX

tDCMSO

2E6E BD E87E

JSR

PDATA1

2E11 BD E1AC

JSR

1NEEE

2E14 61 52

CMP fl

«'R

2E16 27 12

BEQ

DCREAD

2E1B 81 57

CMP A

K-'W

2E1R 27 11

BEQ

DCNRIT

2E1C 81 58

CMP fl

rx

2E1E 27 IB

BEQ

DCEXIT

2E28 81 53

CMP fl

*'S

2E22 27 83

BEQ

DCSTRT

2E24 7E 2E08

JMP

DCNTRL

2E27 7E 0188

DCSTRl

JMP

1188

2E2A 7E 2E6B DCREAO JMP

DIPLR

2E2D 7E 2EFI4 DCURIT JMP

DIPLW

2E30 7E E8E3 DCEXI1

.IMP

MIKBUG

2E33 4C

DCMSG

FCC

/LDRV

2E37 84

FCB

i84

* SUBROUTINES

2E38

DINIT

EQU

*

WIT

IALIZATIOU

2E38 CE 8688

LDX

IDPIfl

2E3B 6F 83

CLR

3,X

SELE

CT DO REG

2E3D 86 83

LDA A

113

SET

CONTROL LINES TO OUTPUT

2E3F A? 82

STA fl

2,X

2E41 86 84

LDfl fl

»*04

2E43 A7 83

STfl A

3,X

SELE

CT CflTPl REG

2E45 28 15

BRfl

DSTAT

2E47

DCOMM

EQU

*

C0MM

AND ISSUE

* INPUT: A=C0MNAND

» OUTPUT: R=STATUS

*

: X=PIA ADDRESS

2E47 CE 8B88

LDX

HDP IA

2E4A C6 02

LDA B

W82

CONN

AND MODE

2E4C E7 02

STA B

2,X

2E4E 6F 01

CLR

LX

2E58 C6 FF

LDA B

MFF

SET

PIA

2E52 E7 88

STA B

0,X

FOR

OUTPUT

2E54 C6 2C

LDfl B

IJ2C

2E56 E7 81

STB B

1,X

HAND

SHAKE

2E58 A7 88

STA A

8,X

CONM

AND

2E5A A6 88

LDA A

8,X

STRO

BE IT

2E5C 6F 81

DSTAT

CLR

LX

2E5E 86 83

LDR R

W83

STAT

MODE

2E68 A7 82

STA A

2,X

2E62 6F 88

CLR

8,X

2E64 C6 2C

LDfl B

B2C

2E66 E7 81

STA B

1.X

2E68 A6 ee

LDfl A

8,X

2E6A 39

RTS

Continued on

next page

BYTE March 1978

183

Listing J, continued:

see

2E6E CE 2EA0 ORDYP2E6I BD E87E2E71 BO EMC2E74 84 6F2E?6 48

2E78 BO 2E4?K

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LDA fl M61 SET

2E98 50

2E91 26 F6

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2E96 2B EF

2E38 8t FI642

2E9D 7E 2ED8

2E9E 66662EA8 492EA3 64

STA RLOSDMORE LOfl BDFWflIT TSTMlLDA flPSH fl

DEC B

2,XB1FFF• 106

2,XDFUAIT

BNE5TSBPLIDS

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DTQ-F FD6

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FC8

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DTEMP

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MA842

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/ID-/184

2ER42CR4 CE 2EA6 BROW2EA7 BD E87E2EAA BD E1RC2ERD 84 BF2EAF 4B

2EB6 46

* DISK IFt KITEDIPLU EfflJ

LDX

JSR

JSR

m • fl

RSL fl

IDRMSGPDflTRlINEEEIMF

2EB1 BO 2647

2EB4 86 21

2EB6 BO 2E47

2EE9 6F 61

2EBB 86 FF

2EBD R7 88

2EBF 86 2C

2EC1 R7 Bl

2EC3 6F 82

2EC5 CE 1FFF

2EC8 ifc 68OflTfl

2ECR F6 8862 DUFlTf2ECD 2B FBFOR FLRG

RSL fl

JSRLOR flJSRCLRLOfl ASTR flLOA ASTA flCIRLDXDULOOP LOR R

LOfl BBUI

DCOMM

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jrp

END

DCCM1

2,X

DTUflIT

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2E382E472E5C2E682E6B2E87

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DTIBIT 2E0D

TOTa ERRORS I

existing programs is allocation of contiguousdisk space to a given file. This type ofallocation has the disadvantages of needing adisk clean up routine to compact unusedspace and also results in more wear at thebeginning of the disk but is much easier todevelop than a system which allows alloca-tion by sectors or pages. Because of therelative ease of implementation the fol-lowing ideas are based on the contiguousallocation design.

Disk Directory

Track 0 should contain a directory of allthe files on the disk. I think the following in-formation should be contained in each diskdirectory entry:

• File Name: 1 to 6 character name used to

locate the file.

• Type: An indicator to show if the file is a

source program, an absolute objectprogram, etc.

• BOE: Beginning of extent. The track and

sector where the first record of thisfile is located.

• EOE: End of extent. The last track and

sector which is allocated to this file.

• EOD: End of Data. The last track and

sector of the file which contains actualdata. The space from EOD to EOE isfor file expansion.

• Delete Elag: Indicates that this file has

been deleted. This is used by the com-paction routine to compress outreleased space.

• Creation of Date and Time: This informa-

tion is optional but space should beallocated for it in case it is added at alater date.

All of this directory information could beeasily contained in 32 bytes with space leftover for expansion. This would result infour directory entries per sector or 104files per disk if all of track 0 were used tocontain this information. Actually, sector1 of track 0 should be reserved for diskheader information and pointers, thusleaving 25 sectors or 100 entries.

Disk Utilities

The following utility routinesnecessary to manage the disk system.

are

List Directory: This program lists direc-tory entries so that the user candetermine what is on the disk andperform any desired housekeeping.

• Define or Delete File: This program

allows the user to delete an existingfile (ie: set the delete flag in thedirectory) and to define the char-acteristics (name, size, type) of a newfile.

• Pack Disk: This utility moves files so that

all allocated disk space is contiguousand updates the file directory,removing the entries for deleted files.When this operation is completed allfree disk space is at the end of thedisk.

• Copy File: Performs a disk to disk copy

or a load from tape to disk or savefrom disk to tape.

Disk 10 Subroutines

The following subroutines must be madeavailable to the applications programs toperform disk 10.

• OPEN: Sets up 10 information about the

file.

• CLOSE: Deactivates the file and updates

the directory entry to indicate anychange.

• READ: Transfer a file block to memory.

• WRITE: Transfer a file block to disk.

• POS: Position a file to a specified file

block.

File Control Block

This is a table which is used to maintaincurrent information about a file while it isbeing used (open). This table is generated atthe time a file is opened. At close time, it isused to furnish the necessary information toupdate the file directory.

Operation Control Block

This is a packet which is created by theapplications program to tell the disk 10handler what operation is desired and onwhat file. Error status can be returned to theapplication by the disk IO handler in thisblock.

These are all the basic pieces necessary toput together a disk operating system. Oncethis is accomplished the applicationsprograms must be modified to use these new10 routines. If all this sounds like a lot ofwork, it is; but when you have all this com-pleted and debugged you should knoweverything about 6800s and disk 10. In factyou have learned so much you can start overand do it so much better. Thus, on goes theendless saga of system software."

184

BYTE March 1978

Location

140 000140 003

Software BootstrapOp Code

303 003 140

(start of bootstrap program)

JMP 140 003

AI4RESET

III

t>

'£*

&

D 0CLK

ADDRESS MODE LINE

ICI74 74

j IC3a\^ T>AI

74 86 I

- I

jlJIXS [}>AI

CLRUPOC

IC274I93

RESET

SYNC

ADDRESSMODE LINE

TIMING DIAGRAM

n

! n n n n n

i i

IC +5V Gnd

Number Description Pin Pin

IC1 7474 14 7

IC2 74193 16 8

IC3 7486 14 7

IC4 7404 14 7

Table I: Power wiringtable for figure I. Notethat as usual ceramic by-pass capacitors of severaltenths of a microfaradshould be used as noisesuppression, wired be-tween +5 V and ground.

Figure 7.' A circuit designed to alio w programmable memory to reside at location 0 in an 8080 'smemory address space, while still allowing a ROM bootstrap permanently in memory. Fol-lowing system reset, this simple circuit forces the system's address lines to map location 0 intolocation 140 000 for the first instruction's execution. If the first Instruction is a jump tolocaton 140 003, the bootstrap can be initiated at 140 003 by an RST 0 instruction forcedonto the data bus during the system reset process. (Addresses other than 140 000 can beassigned to the bootstrap ROM with appropriate modifications of the decoding circuit.)

Get On at the Right Address

The 8080 processor "wakes up" at000 000 (split octal) as people with home-brew systems probably know. My systemhas a bootstrap programmable read onlymemory which initializes my 10 ports(keyboard, cassette interface, and videodisplay) and allows me to load a program.Many available programs originate at000 000 and, although they can be relo-cated, it is more convenient to leave them.Also, the very useful instruction RST(restart n) makes use of memory originatingat 000 000, and, to be effective for differ-ent programs, this memory must be pro-grammable. The problem is to get to thebootstrap first, but reserve programmablememory starting at 000 000 for programs.

The following simple circuit allows animmediate software jump to some othermemory location besides 000 000 (in thiscircuit it is 140 000) where the bootstrapis located. Programs can then be loadedinto programmable memory starting at

000 000. Note that, after the first instruc-tion is executed, addressing returns tonormal in every respect (until anothersystem reset).

The circuit is based on two exclusive ORgates. While the address mode line is high,address lines 13 and 14 will be inverted.This happens at system reset (power on,for instance). At this point the 74193 beginscounting SYNC pulses (one every machinecycle) and at the beginning of the fourthmachine cycle, clocks a low onto the addressmode line, thereby restoring normal ad-dressing. In effect the processor is puttingout address 000 000, but the memoryinterprets it as 140 000. The bootstrapprogrammable read only memory instructionto jump to 140 003 is at this location. AJMP instruction takes three machine cyclesso that, just as the second machine instruc-tion is beginning, addressing returns to thenormal mode and you're on your waystarting at 140 003."

Frank S Holman III611 N 63 StSeattle WA 98103

BYTE March 1978

185

Kenneth R Castleman PhD3655 Figueroa StGlendaleCA 91206

The Intelligent Memory Block

Adding Processors to Enhance Performance

Notice

Neither the author norBYTE magazine assumeany responsibility for theuse of any circuitry de-scribed, and no patentlicenses are implied.

Figure I: The typical"dumb" memory block.This diagram shows var-ious address decode andcontrol logic elements of abus oriented computer's4 K memory block. (Thesame general diagramwould apply as well to an8 K, 16 K, 32 K or 2 Kblock.)

Multiprocessing

If you were to poll a group of computerhobbyists on how to increase the power of aparticular microcomputer system, youwould most likely get two suggestions,namely "add memory and lO devices" and"substitute a faster processor with a morepowerful instruction set." If someonesuggested "add a few more processors,"he/she might draw stares of disapproval.However, the idea is not as farfetched as it

may sound. Multiprocessor systems exist inthe world of big computers (to wit, theIBM 360/65 and the UNIVAC 1108, toname but two) and work well in theirenvironment (see reference 1 at the endof this article). In fact, the arguments formultiprocessing may be much stronger inthe microcomputer world. At any rate,the old one processor per computer ruleneeds reexamination in light of the avail-ability of $20 processor chips.

CENTRALCLOCK<t>2

CENTRALADDRESS BUSAI5 A0

CENTRALRW

CENTRALDATA BUS

LOCALBLOCKADDRESSDECODER

£

BS

BLOCK SELECT

LOCALADDRESSBUFFER(8097 ETC)

33-

BS: BLOCK SELECTCE: CHIP ENABLERW: READ = IWRITE'O

4KX8

PROGRAMMABLEMEMORY BLOCK

0

o

V

BS

DATA BUSTRANSCEIVERS(8835 ETC)

T>

BIDIRECTIONAL LOCAL DATA BUS EXTENSION

186

BYTE March 1978

The Dumb Memory Block

Suppose you find the need to add a4 K by 8 bit block of solid state memoryto your microcomputer. Currently avail-able kits cost from $80 to $150 for a sys-tem with static memory and bufferedbuses. Notice that adding a $20 micro-processor to the 4 K memory block repre-sents only about a 20% increase in partscosts. This article examines how one cantransform a dumb memory block into aslave computer simply by adding a micro-processor (and a few dollars worth of TTLlogic) to the board.

Figure 1 diagrams a typical 4 K by8 bit programmable memory block. Theblock address decoder raises the BS (blockselect) line, enabling the board wheneverthe four high order address bits from the

About the Author

Ken Castleman has a PhD in electricalengineering and works at the Jet PropulsionLaboratory in Pasadena CA. His professionalspecialty is digital image processing, withemphasis on medical images. However,microcomputing is one of his hobbies and,since J973, he has built five microcom-puters, three of which were his own design.This article was motivated by a profoundphilosophical belief that multiprocessorsystems have a role to play in the future ofmicrocomputing but that development inthis field is currently lagging.

$2

V

LPU

DISABLE

LOGIC

I

#f DBE *i

A0

A|5

LPU(6800 OR 6500)

RES

RDY

IRQ

NMI

RW

CENTRALADDRESS BUSA|5 A0

CENTRALRW

BLOCK

ADDRESS

DECODER

^>

CENTRALCE

CEN-TRALRW

LOCAL ADDRESS BUS

0

LOCAL CE

<t>2

LOCAL

ADDRESS

DECODER

LOCALRW

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ADDRESSMULTIPLEXORS

CENTRALDATA BUS

o

V

DATA BUSTRANSCEIVERS

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RW CENTRAL

PROCESSOR

<j>z.

LL

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A HIGH ADDfi-/ DETECT

RW CE ADR

4K X 8

PROGRAMMABLEMEMORY BLOCK

IT

RES'RDY'IRQ'NMI '

CLCONTROLREGISTER(8-BIT

LATCH)

JT

BIDIRECTIONAL LOCAL DATA BUS

SZ

<*>

/

0

CLOCK DRIVER (6800)

'HIGH LEVEL INPUTS(NOT TTL COMPATIBLE)

BS: BLOCK SELECT

RES: RESET

RDY: READY

IRQ: INTERRUPT REQUEST

DBE: DATA BUS ENABLE (6800 ONLY)

CL: CLOCK INPUT

RW: READ= I, WRITE = 0

NMI: NON-MASKABLE INTERRUPT

CONTROL REGISTER ISLOADED WHEN CENTRALPROCESSOR WRITES DATAINTO HIGH ADDRESS OFLOCAL PROCESSOR'S4K ADDRESS BLOCK

Figure 2: The modification of a "dumb" memory block through addition of a second processor and dual port addressing pro-duces an intelligent memory block. Initialization of the additional processor is accomplished by mapping the last address of the4 K memory block into a hardware control word as well as memory.

BYTE March 1978

187

processor specify this 4 K block of memory.The address bus buffers and data bus trans-ceivers prevent the memory chips (32 orso of them) from loading down the centralbuses. A few TTL gates generate the re-quired control signals.

Adding Intelligence

Figure 2 illustrates the addition of anMC 6800 or MCS 6502 microprocessorto the 4 K by 8 bit memory block offigure 1. We shall call this microprocessorthe local processing unit (LPU) to dis-tinguish it from the central processing unit.In figure 2 the address bus buffers have beenreplaced by a bank of 2 input addressmultiplexers. This allows the memory blockto receive addresses from either the centralor the local address bus. The block selectsignal controls the bus routing and thelocal processor disable logic. The latterforces the local processor to stop and re-lease the data bus. The local address decoderallows the local processor to access otherdevices in addition to the local 4 K memoryblock. It is significant that the hardwarecomplication is small, assuming we canaccomplish the local processor disablefunction as simply as figure 2 implies.

Adding the local processor transformsthe 4 K memory block into a microcom-puter. While it has no IO, it can executein-block programs operating on in-blockdata. Since the central processor can stillread and write the memory, it can handlethe necessary IO, and even load the programfor the local processor to execute.

We now have a multiprocessor systemwhere the central processor and the localprocessor share the 4 K block of memory.The central processor can load the localprocessor program and data into the blockand go about its business while the localprocessor processes the data. When thelocal processor is finished, the centralprocessor can read the results out of theblock. Proper division of labor between thetwo processors can produce an extremelyeffective computer system.

The Chain of Command

Considerable cleverness is required forinterfacing the two processors to avoida hopelessly slow and undebuggable mess.

Let us now establish a reasonable set ofinterface requirements.

1. Local processor operation shouldbe transparent to the central proc-essor. This means the central proc-essor should be able to read andwrite the intelligent memory blockas if it were an ordinary dumb mem-ory block. Thus the central processorsoftware need not take special noticeof the intelligent memory block.

2. The local processor should, by default,have control of the local address anddata buses when the central processoris working elsewhere in its addressspace.

3. Memory access conflicts should beresolved in favor of the central proc-essor by stopping the local processorand awarding the local address anddata buses to the central processor.The central processor can then com-plete its memory access withoutdelay. (This assignment is arbitrarysince we could have just as easilygiven memory access priority to thelocal processor.) Care must be takenwhen generating such conflicts toavoid excessive delay of eitherprocessor.

4. Both processors, in general, should runat full speed.

5. Minimum computing time should belost when conflicts occur.

Interfacing Processors

Ordinarily the local processor has controlof the local address and data buses. Whenboth processors attempt to access the blocksimultaneously, one processor (in this casethe local processor) must be stopped imme-diately and made to release the buses to theother processor. This procedure is remini-scent of DMA (direct memory access)operation.

Timing Is Everything

The timing of microprocessor operation iscontrolled by the system clock. We now in-vestigate this area in the hope of findinga resolution for memory access conflicts.The Motorola MC 6800 and the MOSTechnology MCS 6502 microprocessorsuse a 2 phase nonoverlapping clock sig-

188

BYTE March 1978

H

-IpS <t0<5,aS-

0.43<t,<4.5

«->0-.

— >0-»

0.47<t7<4.5

-TIMES IN MICROSECONDS

-MAX. RISETIME 25nS

Figure 3: Typical pro-cessor clock timingrequirements of a 6502 or6800 processor, abstractedfrom the specificationsdocuments.

nal to synchronize all data transfers. Fig-ure 3 illustrates the specifications for 6800and 6502 clock pulses (see references 2thru 4).

Basically, the microprocessor uses <3>i toset up the address and RW lines, and <J>2 totransfer data to or from the specified ad-dress. In a memory read operation themicroprocessor puts the address on the ad-dress bus during $1 and it remains therethroughout <£>2- During $2 tne memoryresponds by putting eight bits on the databus. The data is latched into the micro-processor at the fall of $2. For memorywrite operations the address is set up during<f>1 as before, but this time the microproc-essor puts eight bits on the data bus during$2- The byte is latched into memory atthe fall of <J>2-

Both operations may be summarizedas follows. First, the microprocessor up-dates the address lines about 200 to 300 nsinto <I>i and the address is stable through-out <S>2- Secondly, the memory has therest of $1 and all of $2 t0 decode theaddress and the RW line and either put abyte on the data bus or prepare to accepta byte which the microprocessor puts onthe bus at the beginning of $2- Finally,the actual data transfer occurs at the fall of$2 when the byte on the data bus is latchedinto the microprocessor or the memory.

Marking Time with a Rubber Ruler

Getting back to the problem of establish-ing an interface between the central proc-essor and the local processor, suppose werun both clocks in synchronization. Noticethat conflicts will appear during <t>-| whenthe central processor sends out an addressinside the local block (BS = 1). At thispoint the local processor must be stoppedimmediately. Since the READY line cannot

accomplish this during write operations weneed another solution.

Notice in figure 3 that 4>-| has 4.5 usas an upper limit on its duration. No lawrequires all <J>-|S to be the same length.We can hold the local processor in $1 for upto 4.5 us if we choose. Thus, we can resolveour conflicts with "clock stretching" (seereferences 4 and 5). We can hold the localprocessor in <J>i and take it off the busesuntil the central processor is finished access-ing the block. At that point we allow thelocal processor to go on into $2 ar,d con-tinue its operation. This is particularly nicesince conflicts also go away during <f>^ whenthe central processor addresses a locationoutside the local block. As soon as theconflict terminates we can put the localprocessor back on the buses and let itsclock continue in phase with the centralprocessor clock. This operation is dia-grammed in figure 4 for a conflict lastingtwo clock cycles.

Notice that we have achieved our statedgoals.

1. In operation, the central processoris unaware of the existence of thelocal processor.

2. The local processor proceeds unmo-lested when the central processoris working elsewhere in memory.

3. The central processor never has towait for access to memory.

4. Except during conflicts, both proces-sors run at full speed.

5. The local processor has to wait onlywhile the central processor is actuallyusing the local buses.

Putting It All Together

Referring back to figure 2, we see thatwhen the four high order address bitsselect the local block, the local processor

BYTE March 1978

189

CENTRALCLOCK

Figure 4. Resolving aconflict by the method ofclock stretching. In a 2processor system builtwith the 6502 or 6800,lack of a memory waitfacility requires substitu-tion of a clock stretchingmethod of direct memoryaccess. Here during theasserted state of the BS(block select) signal, thelocal processor (L) has itsclock stretched whilememory is accessed by thecentral processor (C).

o>

^D-

KD ©

LOCALCLOCK

P2

(7) CONFLICT OCCURS

(D CONFLICT RESOLVED IN FAVOR OF CPU

@ CONFLICT TERMINATED

@ LPU COMPLETES EXTENDED CYCLE

disable logic freezes the local processor in<I>-|. The multiplexers route the centraladdress bus to the memory while threestate bus transceivers route the centraldata bus. The DBE input makes the databus float during the stretched <Sfy [Whilethe 6800 also has a TSC (three state control)input which makes it release the addressbus, this input acts too slowly (700 ns)for our purposes.] Anyway, only a fewgates are required to generate controlsignals, and the interface is establishedat little increase in total cost.

Exerting Some Control

Something has to start the LPU andattend to its hardware control functions.A sense of universal justice suggests weshould put the central processor in controlsince it already has its own 10 and startupcapability. In figure 2 the control registeris an 8 bit latch which allows the centralprocessor to supply hardware controlsignals to the local processor. The centralprocessor can address the control registeras the highest byte in the block. Whenthe central processor writes the high byteof the local memory block it simultaneouslysets up the control register. The local proces-sor can modify this byte of local memorybut not the control register. Either processorcan, of course, read the byte but neithercan read the control register itself.

The control register allows the centralprocessor to RESET, HALT and INTER-RUPT the local processor at will. TheRESET function is useful for initiating

program execution after the local processorprogram is loaded. Coming out of RESET,the local processor vectors to a startingaddress stored at the top of its addressspace (see references 3 and 4). The NMIand IRQ interrupt lines of the local proc-essor can also be commanded by the centralprocessor through this control word.

Communicating and Cooperating

We must now establish a protocol forcommunication between central processorsoftware and local processor software.Suppose we wish the local processor tohandle mathematical jobs (such as floatingpoint arithmetic, transcendental functions,etc) or perhaps to update in real timespacecraft position during a complex StarTrek game. Some planning is required toestablish an effective division of laborbetween the microprocessors.

As an example, assume the programmerallocates the local memory block as shownin figure 5. The block is viewed as a con-tiguous region of 4096 bytes with the topbyte dedicated to the central processor'slocal processor control word as described.The central processor must load the programinitially and start the local processor bybringing it out of RESET through the localprocessor control word. Then the localprocessor might execute a loop checkingspecified locations allocated to requestslooking for pre-established processing re-quest codes from the central processor.When the central processor wants a process-ing task done it stores the data in the input

190

BYTE March 1978

Figure 5: Memory allocations within ashared memory block must be understoodthe same way by software of both the cen-tral processor and the local processor.Here we show a schematic representationof a workable allocation scheme for useof the local processor to perform subrou-tines while the central processor goes aboutother business. The only position which isfixed in the hardware of the design infigure 2 is use of hexadecimal locationnFFF in the 4 K block as a command word.

Local BlockHigh Address

CONTROL WORD

LPUPROGRAM

INPUT DATA

OUTPUT DATA

REQUESTS

STATUS

Local BlockLow Address

STACK

VARIABLES

data area, stores a task request code atthe request location, and goes about itsbusiness. The local processor soon detectsthe request and begins program executionto accomplish the task. Periodically thecentral processor checks the words allocatedto status in the local memory block to seeif the task has been completed. When thelocal processor finishes the task it stores acompletion code in a status byte. On itsnext status check the central processordiscovers that the task is complete and itcan use the output data now available inthe output region of the local memoryblock.

In this context the intelligent memoryblock looks like a self-executing subroutine.The central processor and local processorprograms must, of course, agree upon allrequest and status codes and upon thelocations of all variables used in communi-cation. Care must also be taken to ensurethat any central processor access to thelocal memory does not modify data crucialto the computational tasks of the localprocessor during its active execution of atask. Other approaches to the communica-tion problem also could be used. Forexample, the local processor with appro-priate hardware could generate a centralprocessor interrupt each time it completesa task. This would relieve the central proc-essor of periodic checks for task completion.

The Danger of Overstretching

The upper limits on <J>1 and $2 durationquoted in figure 3 exist because the 6800and 6502 microprocessors are dynamicdevices. If the internal registers are notrefreshed often enough they forget theirdata and program execution goes haywire.Thus it is relevant to ask if we are in dangerof stretching $1 to the breaking point.First, it is necessary for the central proc-essor program, stack and zero page to belocated outside the local block. If a central

processor program executes out of the localmemory block, the local processor willbe locked out much longer than the maxi-mum time limit. If the stack of the centralprocessor is in the local memory block,several operations, such as interrupt serviceand return from interrupt take too long.The zero page, since it is frequently refer-enced in many programs as a scratch dataarea, is similarly not a very good choice.Observing these conditions, a 6800 centralprocessor would never address the localblock for more than two consecutive clockcycles with the VMA (valid memory ad-dress) output high. Thus at 1 MHz opera-tion, $-| would never be stretched beyond2.5 11s.

The 6502 has no VMA output and,in the worst case (shift instructions address-ing data in an absolute X indexed mode),would access the local block for four con-secutive clock cycles (see reference 3). At1 MHz clock operation this stretches $1to the legal limit of 4.5 jus. We can circum-vent this possibly marginal situation withone of the 6502A parts which can run atspeeds up to 2 MHz.

Another Way

For 6800 and 6502 microprocessorsthere is an alternative memory sharingtechnique which does not involve clockstretching and results in maximum speedfor both processors. This technique isknown as clock multiplexing. The centraland local processor clocks are run in oppo-site phase. While the central processor isin $1 the local processor is in $2 and viceversa. Two input multiplexers and datatransceivers switch the address and databuses from central processor to local proc-essor and back every clock cycle. This waythe memory is always connected to which-ever processor is in $2 at tne moment.Since data transfers only take place in $2this is adequate.

BYTE March 1978

191

Clock multiplexing gives both processorsunlimited access to the memory. The onlypenalty is that faster memory is requiredfor the same clock frequency. Since thememory sees the address only for one $2period it has less time to prepare for adata transfer.

Note that the clock sharing technique

Hierarchy Diagram of Multiprocessor System

Level 0

<J>2 = clock phase A

Local

Processor

0

Local

Processor

1

Local

Processor

2

LocalProcessor3

CentralProcessor

Shared

Memory

Boundari

3S

Level 1

clock phase B

Five Processor Central Processor Memory Address Space Map

Central Processor

Hexadecimal

Address Range

0000-OOFF0100-7FFF

8000-8FFF

9000-9FFF

AOOO-AFFF

BOOO-BFFF

COOO-FFFF

Contents

Page 0 scratch area

Central processor main memory area which is not sharedwith local processors. This area contains central processorprograms and stack.

4 K byte local processor 0 memory overlap region.Address 8FFF is local processor 0 control word.

4 K byte local processor 1 memory overlap region.Address 9FFF is local processor 1 control word.

4 K byte local processor 2 memory overlap region.Address AFFF is local processor 2 control word.

4 K byte local processor 3 memory overlap region.Address BFFF is local processor 3 control word.

Spare address space tor more local processors and readonly memory. Interrupt and reset vectors for centralprocessor at locations FFF8-FFFF.

Figure 6: A multiprocessor system involving more than one intelligent mem-ory block is conceivable. If each intelligent memory block shares a differentaddress space segment with the central processor, and all the intelligentmemory blocks (local processors) use an inverted version of the centralprocessor's clock, then there can never be any hardware conflict betweenoperation of the multiple processors. Software considerations as in figure 5are required to establish consistent communication.

can be used to implement multiple processorsystems with more than two processors.This is possible if we dedicate one phaseof the clock to the central processor, anddedicate an exclusive memory address spaceregion (and the second clock phase) to eachlocal processor. Figure 6 shows a hierarchydiagram of a 5 processor system alongwith an address space allocation diagramfor the central processor. All four localprocessors use the $2 clock of the centralprocessor as their 3>-| clock; since the centralprocessor can never address more than onelocal processor's local memory block at atime, there is never any conflict betweenlocal processors.

Getting Fancy

The intelligent memory block is a bonafide microcomputer in its own right. Thelocal processor, with its vast unused addressspace, is capable of much more than playingbutler to the central processor. For example,the local processor could do some externalinterface job like refreshing a video displayor running a multichannel analog IOinterface.

Now that we have shed the "one com-puter-one processor" myth, our horizonshave broadened indeed. A 16 K byte micro-computer might just as well have one dumband three intelligent 4 K blocks as fourdumb blocks. What started as an inexpensiveway to augment a memory block has landedus knee-deep in exotic computer architec-ture. Each local processor could even haveseveral sub-iocal processors working forit in a 3 level architecture, and of course,the possibilities do not end there. At $20per microprocessor chip, a small computingbudget could support a lot of advancedarchitecture in the family microcomputer.In response to the question "why an intelli-gent memory block?" one might respond"for twenty bucks, why not?" ■

REFERENCES

1. Enslow, Philip H Jr (Ed), Multiprocessors andParallel Processing, John Wiley and Sons,New York, 1974.

2. "MC6800 Data Sheet," Motorola Semicon-ductors, POB 20912, Phoenix AZ 85036.

3. "MCS 6500 Microcomputer Family HardwareManual," MOS Technology Inc, 950 Ritten-house Rd, Norristown PA 19401.

4. "Microprocessor Applications Manual," Moto-rola Semiconductor Products Inc, McGraw-Hill,Hill, New York, 1975.

5. Henshaw, Jerry, "Stretch That 6800 Clock,"BYTE, December 1976, pages 42 thru 46.

192

BYTE March 1978

"LSI-11 vs. 8080 & 6800:is the HI 1 worthtwice as much?"

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Cybernetics

S4*VE <S tc 15%

LIST SALE PRICEIMSAI 8080 W/22 SLOTS S751 S649

POLYMORPHICS SYSTEM 2 $735 $675

SHUGGARTMODEL 800 S650 S595

SIMILAR DISCOUNTS ON:IMSAI 4K, 16K. 32K RAM, MIO etc.POL YMORPHICS VIDEODYNA8YTE WK (ACM) RAMMICRODESIGN 2708/2716EPROM BOARDOUANTRONICS SK (ASM) RAMIIJS 8K (ASMI RAMPROCESSOR APPLICATIONS DMA FLOPPY

DISC CONTROLLER (ASMITARBELL FLOPPY DISC CONTROLLERTARBELL CASSETTE INTERFACESHUGGART MODEL 850 TWO SIDED FLOPPY

DISC DRIVEALL SWTP PRODUCTSAPPLE II

MODEL 43 TELEPRINTER (OCTOBER!ADM 3A TERMINALSOROC IOI20 TERMINALREPAIRS IN HOUSE AT LOW COSTCUSTOM SOFTWARE S FIRMWARE

in Santa Barbara, CA Opening Soon InCall (8051 968-0302 Sanla Ana. CA

THE CLUPLITER STQP

16919A Hawthorne BlvdLawndate CA 90260(213) 371-4010

11:30 10 7:30 Tue-F11 to 6 SatClosed Sunday /Monday

CALIFORNIA

APPLIEDTECHNOLOGY

32K-MEM0RY CARD-S410S-100 STATIC KIT

2708E-PR0M-S14

2708 PR0GRAMMED-$20

WITH 8060 SYSTEMS MONITOR

80 MAJOR COMPUTER PRODUCT LINESAND AN EXHAUSTIVE LINE OFELECTRONIC COMPONENTS

COMPUTERS

HARDWARE AND SOFTWARECUSTOM HARDWARE AND SOFTWARERESEARCH AND DEVELOPMENT

P 0 BOX 1239

TWENTYNINE PALMS. CA. 92277

714-3B7-699B

FREE BASIC PROGRAM AND CATALOG

'ALEX IS COMING'

Circle 99 on inquiry card.

Circle 122 on inquiry card.

Circle 12 on inquiry card.

BUSINESS PROGRAMS FOR SWTPC

Editor - Letter Writer* $100

Math Package* t II', digit accuracy with Ireefonnat and Fortran type lormatlmg on read

and write $100

Payroll" $400

Inventory* $400

Utility Package (Hex Loader Mikbug- lor-

nailed dump with spaces) $ 10

Single Step Debugging Program* (withmnemonics, regisler display, and user se-lectable RAM display RequiresMP-T) $ 29

Power Supply Modification Kit lor SWTPCComputer (Fill mother board with as nuch

memory as you wish wilhou! voltage drop) $ 20

SWTPC Dlek Conversion Kit (Connect yourSWTPC disk dnves, cabinet, and powersuoply to Smoke Signal Coniroller Board anduse Smoke Signal Operating System and oursoUware Price includes Smoke Signal con-iroller boardar>loperating systemi $269

208 Megabyte GIMIX Memory (or SWTPC

(Phone loi details)Software Addressable GIMIX 16K MemoryBoard to< SWTPC (Faciliitales time sharing.

multitasking, large programming) . $985

4K GIMIX Prom Board and Programmer $259

Dealer for SWTPC. Smoke Signal BroadcastingPercom GIMIX Moiorola. Tl. GE Teletype" DECCentronics Lear Siegter. Soroc etc

AAA Chicago Computer Center

3007W W Waveland Ave . Chicago. IL 60618(312) 539-5833 (3 PM-5 PMonly)

'Original putchaui to unlimited lifetime upgrade guarantee."Oiiginal pmenaur has qualified lifetime upgrade guarantee

INDUSTRIAL QUALITY

MICROPROCESSOR CARD KITS

All +5V only, std 4.5 x 6.5. 22/44 edge conn.

• 4 K RAM S79.95 • 2 K PROM S 79.95

• Motherboard S39.95 • 4 K PROM $129.95

• Card Cage S20.00 • Digital I/O $ 59-95

• Keybonrd/Display S89.95 • Cassette Interlace S 37.95

• Available resied and in OEM qtys.

MICROCOMPUTER SYSTEMS

• 6800 Prototyping Board Starter Sot

S 84.96

• Kit &]. 6800 Student Computer

$125.00

• Kit #2. Motorola Educator II

$169.50

• Kit #3, 6800 Industrial Card Set

S2I0.00

• Kit £4. Homebrew Computer Card Set

$320.00

KIM EXPANSION SYSTEMS

• KIM Interface Adapter

$24.95

• KIM Komputer Enclosure

S80.00

• BARE BOARDS, ENCLOSURES, FIRMWARE,ETC. SEND S3.70 FOR TECHNICAL MANUAL(INFORMATION ON ALL ABOVE).

Auilver 0

pur

Electronic Communications Co

P. O. Box 365, Chino, CA 91710or Visit Retail Store:13552 Ccntfal Avenue

' VISA

1 Mastetcharge1 Calif Residents Add6% Sales Tax

ThE

= CQMPIJTER^^ HARDWARE

STORE JNC.

Dealers for:

APPLE II, IMSAI

VECTOR GRAPHIC, KIM-1

TECHNICO, OAE

CYBERNEX, JIM-PAK

TERMINALS, PRINTERS

BUSINESS SYSTEMS, BOOKS

SOFTWARE AND MUCH MORE

CATALOGUE AVAILABLE

81 8 Franklin Street 9 West Cary StreetAlexandria, Virginia Richmond, Virginia(703)548-8085 (804)780-0348

Circle 1 on inquiry card.

Circle 104 on inquiry card.

Circle 27 on inquiry card.

COMPUTER

PRINTER KEYBOARD

TERMINAL

$160 - $270

depending upon optloni: paper tape punch,paper tap* reader, Upper 1 Lower case

FULL STANDARD KEYBOARD550CHAR./MIN. UP TO 150CHAR./LINE

Complete Instructions & circuit diagramsIncluded for ASCII Microprocessor and TTYInterlace.

Interlace components are standard; UART. PROM, ICs, elc.cost about J95. can be obtained Irom many suppliers (NOTIncluded with above terminal)

Terminals are used, trom operating computor systems

Refurbished and Checked Out Before ShippedOnly 63 /eft in stock, subject to prior safe

FOR DETAILS WRITE

L. E. LABORATORIES

2689 LIMEKILN PIKE QLENSIDE, PA. 19038

SERVICE!!!

TIRED OF WAITING 2 MONTHS?

NationalDigitalDiagnostics... can helpw.

Your equipment is ordinarily on its wayhome within 5 days of its arrival.

SPECIALISTS IN SERVICING OF:

All S-100 Bus Micro Processors & Peri-pherals, TTL Circuits, "Home BrewProjects", other Micro Processors.

■ Estimates Given Before Work is Done

- Equipment Returned C.O.D.

WHEN SENDING EQUIPMENT:

■ Ship via UPS Insured,

- Include hardware documentation & Sche-matics, if available,

■ Include flat rate diagnostic fee of $10 in checkor money order. (Will be applied against costof any repair work done.)

FOR MORE INFORMATION CALL:N t*.C. (212)929-1694

NATIONAL DIGITAL DIAGNOSTIC

P.O. BOX 728 ■ NEW YORK, N.Y. 10011

COMPUTER MARTOF

NEW HAMPSHIRE

• •

DEALERS FOR:

\H3J AND MANY MORE

• •

170 MAIN STREETNASHUA (603) 883-2386

Circle 61 on inquiry card.

Circle 79 on inquiry card.

Circle 28 on inquiry card.

What's New?

Tl's First Personal Computer?

Furniture Designed to Hold ComputerEquipment

Low Cost Logic Probe

1

These desks are specially made tosupport video displays, terminals, wordprocessing stations and similar equip-ment. Options such as cutouts for cables,cable channels to eliminate loose cords,pedestals and storage compartmentsare available. Standard sizes range from36 inches to 60 inches wide in a varietyof colors, from Electronic SystemsFurniture Co, 1215 E El Segundo Blvd,El Segundo CA 90245, (213)322-4612.■

Circle 637 on inquiry cnrd.

This low cost probe features lightemitting diodes which indicate high andlow logic states and pulses for eitherTTL or CMOS logic families. Separatedual window comparators drive the highand low LEDs. The pulse detection cir-cuit catches pulses as short as 300 nswith a positive or negative going leadingedge. Individual pulses cause the LED toblink for a tenth of a second, while apulse train flashes it continuously. Theprobe obtains power from the systemunder test through a standard phonojack power connector, with a matingcable ending in alligator clips. The probeinput impedance is over 300 K ohms.The LP-2 logic probe is $24.95 from Con-tinental Specialties Corp, 44 Kendall St,New Haven CT 06509, (203) 624-31 03."

Circle 633 on inquiry card,

Fuel Your Appetite for a 16 Bit System

An 8 page brochure describes theAlpha Micro system, a powerful Altair(S-100) bus. compatible package with atimeshared operating system includingutilities, a multiuser structured filesystem with password security, disk filemanagement for floppy or hard disks,AlphaBASIC extended compiler andreentrant run time software, free formtext editor and formatter, multiple passmacroassembler and 16 bit micro-processor with hardware floating pointcapabilities. The microprocessor is builtfrom the Western Digital WD-16 chip set,also used in the LSI-11. The brochure isavailable from MicroAge, 803 N Scotts-dale Rd,Tempe AZ 85281.*

Circle 642 on inquiry card.

New Test Equipment andHobby Catalog

This 32 page catalog features a com-plete line of electronic kits and factoryassembled instruments, burglar and firealarm systems, citizens' band accessoriesand hobbyist kits. New test instrumentsinclude a portable digital multimeter,and function generator, a portable colorgenerator, a digital frequency counter,two new oscilloscopes, a self servicetube tester and a digital power supply.New hobbyist products include anignition and engine analyzer and analpha brainwave monitor. The catalogis available from EICO Inc, 108 NewSouth Rd, Hicksville NY 11801, (516)681-9300.-

Circle 641 on inquiry card.

End Stackable Sockets

These low cost sockets can be stackedend to end to build a continuous stripsocket. The CS2 line is available in allsizes from 8 to 40 pins, from CircuitAssembly Corp, 3169 Redhill Av, CostaMesa CA 92626, (714) 540-5490."

Circle 640 on inquiry card.

Billed as a "personal computer/calculator," the SR 60A is said toform the heart of a versatile businesssystem that provides the power of acomputer with the simplicity of useand low cost of a calculator. TheSR 60A uses a microprocessor to con-trol an optional letter quality typewriterand up to two digital cassette drives withfile management capability. Serial com-munications capability also is available.The SR 60A is capable of handlingbusiness problems such as inventory,payroll, general ledger, accounts receiv-able and others. Over 250 programs areavailable for the machine. Under pro-gram control, a small alphanumericdisplay prompts the user for inputsand performs the calculations, whilea 20 character alphanumeric printercan be used to record results. Thebasic machine provides up to 2640program steps or 330 data registers,expandable to 7920 program stepsor 990 data registers. Prices for theSR 60A start at $1995 from TexasInstruments inc, Inquiry AnsweringService, POB 53 (Attn: SR 60A),Lubbock TX 79408."

Circle 639 on inquiry card.

Attention Readers, andVendors...

Where Do New Product ItemsCome 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 neat new whiz-bang gizmo or save the worldsoftware package is of interestto the personal computing experi-menters and l)omebrewers whoread B YTE, we print the informa-tion in some form. We openlysolicit such information frommanufacturers and suppliers tothis marketplace. The informationis printed more or less as a first Infirst out queue, subject to oc-casional priority modifications.

196

BYTE March 1978

Circle 6 on inquiry card.

4K RAM BOARD

Assembled and tested. ^IIA #% Jg

See kit below.4K RAM BOARD KIT

450ns Access RAMs

Fully Buffered

Low Power $79.95

Static

5V only

4y2 x 6 inch board

Buy 4 RAM Board kits at$79.95 each and an 8 slotMother Board is yoursIncludes 8 connectors and card guides. FREE.

MOTHER BOARD

8 SLOT 44 PIN BUS

50 Pin Edge Connector

KIM INTERFACE

Board plugs into Kim expansion connectorConnector for our Mother BoardFull memory decodingWrite protect for (4) 4K bytesAddress and data Bus buffers

Mother Board $20.00 eaConnectors 2.50 ea

Card guides for above $10.00 per set.

2102 — $1.20 Multiples of 25 only.Low power, 450 n.s. Access and cycle.

8K EPROM BOARD

5 Volt only For our bus

MAKE CHECK OR MONEY ORDER PAYABLE TO:

Kathryn Atwood EnterprisesP.O. Box 5203, Orange, CA 92667

Discounts available at OEM quantities. For orders less than$25.00 total, add $1.25 for shipping. California residentsadd 6% sales tax. Estimated shipping time 2 days ARO withmoney order. For checks allows 7 days for check to clear.

m Electrolabs

415-321-5601

POB 6721, Stanford, CA 943Q5

ESAT-100A: REVISED DESIGN ! For Teletype, SC/MP, Jolt,Kim, SBC80, COSMAC. Electrolabs Stand Alone Terminal. Com-pletely assembled, burned in and tested. Very reliable. $239.00

64 CHAR X 16 LN X 1 PC of 5X7 dot matrix ASCII, communicating with aserial, asynchronous 1 1 unit code, TTL compatible, 300 to 9600 Baud. Keyboardsare: BACK SPACE, FORWARD SPACE, LINE FEED, CLEAR PAGE,FULL-HALF DUPLEX, LOCAL/REMOTE,

ODD/EVEN,NO, 75

CLEAR LINE, .CURSOR ON/OFFPARITY. Output

Ohms. Keyboard required is parallelout 7 unit ASCII with negative truestrobes. Keyboard may tap up to 200MA from the onboard 5V supply. Pow-er required: 1 10 VAC @ 7 watts. Youdon't even need a computer, S-100 orotherwise. May be used with Modernfor time-share terminal applications.MODEM : Bell 103 Std. Vadic Card witoriginate & answer S75.O0

DAA KIT (for above) 9.95

«■ m mm m\\

mm mm mm.t]

agmmmmmtu mmm.mmi\«7|Blll||f!l

L.C. Option $39.00

EPROMS

2716

$39.00

2708

450ns

11.95

2708

650ns

8.95

S204AQ

7.95

5203AQ

3.95

1702 A

3.95

RAMS

21L02

250ns

S 1.59

21L02-3

450ns

1.19

F2101LIPC

450ns

1.68

2111 AL-4

450ns

1.99

2114-3

300ns

10.95

2606-1

500ns

1.75

C3I07-B

60 ns

1.49

PD411D

135ns

3.99

PROMS

82S2708

50 ns

$22.95

MEMORY BOARDS

MLM-100-8KB $139

8K static for S100 bus, assembled, burned in and

fully tested.

MEM-11-24KB $679

for PDP11-03or Heath kit LS1-11. 24 KBy of RAMand 2KBy of 2708 ROM. Beautifully done board.Qualified through tests your CPU would flunk. Re-fresh CPU controlled. Includes 2708's.

OTHER NOTABLE ITEMS

Z80+XTAL S27.95 N3002 Bit Slice CPU S3.95

Z80A+XTAL 33.95 LS703 1 8 decade CTR +

8080A 10.95 display driver up to 500

2513 Char Gen 5.95 MHz w/external BCD

AY5-I013 4.95 CTRs S15.95

MM5320 4.95

\ferbatim

MiniDiskettes

Removable Magnetic Stprage Mediamanufactured byInformation Terminals Corp.

1-9 10-25 26-100

$4.79 $4.65 $4.45MD525-01 (Soft Sector) for: Intelligent Systems, Magnavox, Microkit and

Vector GraphicsMD525-10 (10 Sector) for: Digi-log, North Star, Polymorphic, Tei Inc., WangMD525-I6 (16 Sector) for: Altair, Comtek, Micropolis, R2E, Realistic Con-trols and Teleray Research Inc.

Standard Size Diskettes

1-9

10-25

26-100

FD34-1000 (Soft Sector, IBM Std.

$5.99

$5.33

$4.79

FD32-1000 (Hard Sector, Inner dia.l

FD65-1000 (Hard Sector, Outer dia.)

Cassettes

1-9

10-25

26-100

R-300 Digital Direct

$5.25

$4.99

$4.35

SYSTEM BUY OF THE YEAR! TEALTRONIC 2500

includes 165cps bidirectional matrixprinter, ASCII keyboard, wide bandvideo monitor, FOUR Shugart 800floppy drives, high speed CPU struc-tured from 2900 bit slice chips toexecute in IBM's ACL business lan-guage and containing 32K of memory.Regulated, protected cool runningsupplies for all of these items.

NOTE: In Europe these felchS19,000. One of these with aLSI-1 1 would be incomparable !

All New In Console

including softwareWith 2 Drives

$5775S3900

100% GUARANTEE ! We offer a money-back guarantee on the products thatwe sell. Full refund or replacement for any unsatisfactory products returnedwithin 15 days of purchase. Our magnetic media is certified 100% error-free,shipped fresh from refrigerated storage. FREE CATALOG ! Free catalog ofIC's, components, word processing supplies, useful devices and equipment willbe sent in response to each inquiry and order. Call for information on quantityprices and special discounts.

ORDERS NOW BEING TAKEN FOR: THE NOT-SO-DUMB TERMINAL 80 char.X50 In. rolling full ASCII stand alone communi-cating Z-80 based terminal. Smarter than the "Owl,"includes EBCD to ASCII translator. Options for 256X256graphics. 100 lines, full editing,etc. Requires KDB and a reasonable monitor such as a slightly modified TV. $489.00

Circle 42 on inquiry card.

BYTE March 1978

197

What's New?

New Line of Prototyping Boards

PERIPHERALS

Analog IO for Motorola Exorciser

The MP7400 Analog 10 System iselectrically and mechanically plug com-patible with the Motorola Micromoduleand Exorciser microcomputers. Eachanalog system can accommodate up to64 single ended or 32 differential inputchannels and two output channels. Ahigh gain instrumentation amplifierhandles input levels as low as 10 mV.The unit interfaces to the micropro-cessor through a set of memory loca-tions. In single quantities, an input onlyboard with eight differential channelsis $295, while a fully loaded board with32 differential channels and two outputchannels is $595, from Burr-BrownResearch Corp, Intl Airport IndustrialPk, POB 11400, Tucson AZ 85734,(602) 294-1431."

Circle 631 on inquiry card.

Floppy Disk Emulates Tape

This floppy disk drive and micro-processor based controller is designed toemulate paper tape and magnetic tape.The unit can be used for data collectionor offline preparation of messages whichcan then be transmitted through theoptional built in acoustic coupler. Theunit will operate with any standardprinter or video terminal through anRS232 interface. The program con-trolling the unit resides on a floppy diskrather than in read only memory, so thesystem can be easily updated. TheDigidisk with RS232 interface is $1199,$1299 with a built-in originate onlyacoustic coupler, and $1699 with a1200 bps Bell 202 compatible coupler,from Digicom Data Products Inc, 1440Knoll Circle, Suite 108, San Jose CA95112, (408) 279-8711."

Circle 634 on inquiry card.

The Before Boards are prototypingboards for the Altair (S-100) bus andthe SWTPC (SS-50) bus, offered bothwith and without a regulated powersupply circuit. The S-100 Before Boardis supplied with a 100 pin edge con-nector and can accommodate 56 14pin or 50 16 pin dual inline pack-ages, and has an extra wide A row toaccommodate .4 to .6 inch wide pack-ages. It includes the power supply circuitand is priced at $29.95. The S-100xversion of the board omits the powersupply circuit for $28.45. The 6800Before Board is designed to be used with50 pin Molex connectors and is priced at$23.95, while the 6800x version, whichomits the power supply circuit, is$22.46. The boards are available fromMulti-Tek Inc, POB 201 Union Square,Milford NH 03055, (603) 673-5011."

Circle 635 on inquiry caid.

*%&***

.95

4525 *

The Programmable

Scientist

MODEL No. 4525 - 100 STEPS

100 STEP LEARN MODEKEYBOARD PROGRAMMING CAPABILITY

• RPN Logic • Rollable 4-level stack • 8-digit plus 2-digit exponentLED display • Scientific notation • Sine, cosine, tangent & inversetrignometric functions • Common & natural logarithms & antiloga-rithms • Instant automatic calculation of powers and roots • Single-key square root calculations • Single-key PI entry • Separate storagememory • Square, square root and reciprocal calculations • Changesign & register exchange keys • Includes NiCad batteries.

Manufactured by National Semiconductor - 1 Year WarrantyA.C. Charger $4.95 Protective Case $2.95

Shipping and Handling - $3.50_ California residents add 6% sales tax

ELECTRONICS WAREHOUSE Inc.

1603 AVIATION BLVD.REDONDO BEACH, CA. 90278

TEL. (213)376-8005WRITE FOR FREE CATALOG

You are invited to visit our store at the above address

3RD GENERATION

ASCII KEYBOARD KIT

*°i63.0(>

FURTHER IMPROVEMENTS-MORE FEATURES

TTL Logic CircuitsPower: +5V 275mAUpper and Lower CaseFull ASCII Set (AlphaNumeric , Symbols,Control)

7 or 8 Bits Parallel DataOptional Serial OutputSelectable Positive orNegative Strobe, andStrobe Pulse WidthTNT Key Roll-OverFully DebouncedCarriage Return KeyRepeat Function KeyShift Lock, 2 Shift Keys4 User Defineable KeysP.C. Board Size:!7-3/16"x5"

OPTIONS:

• Metal Enclosure (PaintedIBM Blue and White)

$25.00

• 18 Pin Edge Con. $2.00

• I.C. Sockets $4.00

• Serial Output (ShiftRegister) $ 2.00

• Upper Case Lock Switchfor Capital Letters andNumbers S 2.00

KIT Includes: Keyboard,P.C. Board, all required com-ponents & assembly manual.

NOTE: If you have this 63Key Teletype Keyboard youcan buy the Kit without itfor only $44.95

198

BYTE March 1978

Circle 45 on inquiry card.

Industrial Quality Analog Input Systems

Bidirectional Telephone Interfacefor 6800 Systems

Cartridge Tape System for IntelMDS and SBC 80 Users

These analog input systems forMotorola microcomputers offer 12 bitresolution on digital conversion andbetter than .025% full scale rangethroughput accuracy. The boards featureinput and overvoltage protection andexcitation and bridge circuitry. Themodel MP7608 provides eight differen-tial input channels which accept signalsranging from ± 10 mV to 5 V, whilethe model MP7608-I is a current inputsystem designed to interface to 4 to 20mA current loop signals. Both are pricedat $595 in single quantities, fromBurr-Brown Research Corp, Intl AirportIndustrial Pk, POB 11400, Tucson AZ85734,(602) 294-1431."

Circle 636 on inquiry card.

This touch tone transmit modulecontains a central office quality tonetransmitter and receiver and is suitablefor applications such as automaticdialing and receiving and automaticcredit card verification. The module isbuilj on an industry standard 4.5 by 6.5inch 44 pin printed circuit board and ispriced at $1499 in single quantities,from Wintek Corp, 902 N 9th St,Lafayette IN 47904, (317) 742-6802."Circle 632 on inquiry card.

Designed for use with the 3MDC100A tape cartridge, this systemconsists of a single or dual drive mech-anism with power supply and cabinet,and a low cost controller for the IntelMicrocomputer Development Systemand the SBC 80 microcomputer. Thecontroller can also be used with the 3MDCD-1 mini cartridge drive. TheDatamax mechanism features a lowerror rate, 100 K byte capacity, and adata transfer rate of 2350 bytes persecond. The controller and mechanismare available from HT Instruments Inc,4121 Redwood Av, Los Angeles CA90066,(213) 822-4296."

Circle 633 on inquiry card.

^1

MICROPROCESSORS

FROM CHIPS TO SYSTEMS

Rodnay Zaks

420pp, 150 illustr, ref C201 $9.95

Our Bestseller. This book is the result of theauthor's experience in teaching microprocessorsto more than 2000 persons. It presents a com-prehensive introduction to all the aspects ofmicroprocessors, from the components to theassembly of a system. The difficulty of eachchapter is graduated from the basic conceptsto the actual technical details. It is read bystudents, technicians, managers, engineers,educators, doctors and by all those who wish tounderstand rapidly and efficiently all the important aspectsof microprocessor use, selection, or application.CONTENTS: Fundamental Concepts... Internal Operation of aMicroprocessor... System Components... Comparative Micro-processor Evaluation... System Interconnect... MicroprocessorApplications... Interfacing Techniques... Microprocessor Pro-gramming. .. System Development... The Future...

ALSO AVAILABLE: MICROPROCESSOR ENCYCLOPEDIA

• VOL I: 8-BITS, ref E8 $15.00

• VOL II: BIT-SLICE, ref E5 $15.00

TO ORDER

• BY PHONE: call (415) 848-8233BankAmericard/Mastercharge accepted

• SHIPPING: no charge when paymentincluded.ADD: $1.00/book for fast shipping.

• TAX: in California, add sales tax.

• OVERSEAS: 66 French Francs. Write to:SYBEX-EUROPE, 313 rue Lecourbe75015 - PARIS, France Tel:(1)8282502

MICROPROCESSOR

INTERFACING

TECHNIQUES

Austin Lesea, Rodnay Zaks350pp, 320 illustr, ref C207 $9.95

MICROPROCESSOR

INTERFACING

TECHNIQUES

FROM KEYBOARD TO FLOPPY DISK: All thebasic concepts and techniques for assemblinga complete microcomputer system are presentedin detail, with over 320 illustrations or diagrams,including teletype, keyboard, floppy disk, CRTdisplay, analog /digital interfacing. One chapteris dedicated to the bus standards, includingS100, and IEEE488, and one chapter to testingand debugging.

CONTENTS: Introduction... Assembling the Central ProcessingUnit... Basic Input-Output... Interfacing the Peripherals... AnalogConversion... Bus Standards... Case-study: a 32-channel Multi-plexer... Digital Trouble-Shooting... Conclusion-Evolution.

DISTRIBUTION/TRANSLATION INQUIRIES INVITED

2161 Shattuck Ave.Berkeley, Ca 94704Tel: (415) 848-8233

| NAME

i COMPANY

POSITION

j ADDRESS

; CITY

{ □ Send me:

DC201nclosedID $1.00□ Visa

STATE/ZIPDC207 D Other:

! □ Payment eAC] □ charge myi □ Number

□ Bill company □ Bill me

/ BOOK FOR FAST SHIPPING

□ Master charge

Fxp date

i Signature

n Rend catalog

BYTiLzaa

Circle 118 on inquiry card.

BYTE March 1978

199

What's New?

SILICON

Audio-Digital-Audio Processors,Anyone?

Single Chip 8 Bit Digital to Analog Converter

This microprocessor bus compatiblechip incorporates a complete 8 bit digitalto analog converter. The NE5018includes a 5 V stable reference, a highslew rate buffer amplifier, a digital toanalog converter and an 8 bit inputlatch. The device has a typical settlingtime of 2 jus, requires supply voltages ofIS and ~15 V and is priced at $6.95 inquantities of 100 from distributors ordirect from Signetics, 811 E Arques Av,Sunnyvale CA 94086, (408) 739-7700."

Circle 629 on inquiry card.

Chip Offers Memory Plus 10 Ports

The INS8154 combined memory andinput output chip is well suited to lowend microprocessor applications. Itincludes 128 bytes of programmablememory and two 8 bit parallel IO ports.The chip is designed so that each bit ineither port can be set, reset or read witha single microprocessor instruction. The40 pin package is priced at only $8.75 in100 piece quantities, from NationalSemiconductor Corp, 2900 Semicon-ductor Dr, Santa Clara CA 95051, (408)737-5000."

Circle 630 on inquiry card.

The DF331 and DF332 are completeanalog to digital and digital to analogcoders and decoders, respectively, whichtogether meet the need for per channelvoice frequency "codecs" in pulse codemodulation telephony and audio appli-cations such as microprocessor analysisof speech. The DF331 converts up to an8 kHz bandwidth signal into a high speedserial digital format, while the DF332accepts the serial digital format and con-verts it back to an audio signal. The codemade with these parts meets all Bellstandard /U-255 law specifications, uses alow power CMOS design and avoidsexpensive trimmed resistive conversiontechniques. The pair of 14 pin chips ispriced at $9.76 in 100 piece quantities,from Siliconix Inc, 2201 LaurelwoodRd, Santa Clara CA 95054, (408)246-8000."

[®] CLjbercDm boards

MB-1 MK-8 Computer RAM (not S-100), 4KX8, uses

2102 type RAMs, PCBD only $22.00

MB-3 1702A EROM Board, 4KX8, S-100, switchable

address and wait cycles, kit less PROMS $58.00

MB-4 Basic 4KX8 ram, uses 2102 type rams, maybe expanded to 8KX8 with piggybacking, S-100

buss. PC board $29.95

MB-6 Basic 8KX8 ram uses 2102 type rams, memoryprotect in 256 to 8K switchable S-100 buss.

PCBD $26.00

MB-7 16KX8, Static RAM uses „P410 Protection,fully buffered.

PCBD S29.95 KIT $400.00

MB-8 2708 EROM board, S-100, 8KX8 or 16KX8 kit

without PROMS $65.00

MB-9 4KX8 RAM/PROM Board uses 2112 RAMS or82S129 PROM kit without RAMs or PROMs ....$75.00IO-2 S-100 8 bit parallel 1/0 port, % of board is for

kludging. Kit $46.00 PCBD $29.95

IO-4 Two serial I/O ports with full handshaking20/60 ma current loop: Two parallel I/O ports.

Kit $130.00

VB-1 64x16 video board, upper lower case Greek,composite and parallel video with software, S-100.

Kit $130.00 PCBD $29.95

SP-1 Music synthesizer board, S-100, computer con-troller wave forms, 9 octaves, 1V rms Vz % distortion,

includes software kit - $180.00

Altair Compatible Mother Board, 11 x 111$ X Ve".

Board only $42.00. With 15 connectors .$99.00

Extended Board full size. Board only $9.00

With connector $13.00

Solid state music Cybercom boards are high qualityglass board with gold finger contacts. All boards arecheck for shorts. Kits only have solder mask. 90day guarantee on Cybercom kits.

W777C

inc.

WAMECO INC.

MEM-1 8KX8 fully buffered, S-100, uses 2102 type

rams. PCBC $26.00

Mother Board 12 slot, terminated, S-100, board

only $35.00

CPU-1 8080A Processor board S-100 with 8 level

vector interrupt PCBD $30.00

10% discount on 10 or more of WAMECO PCBDin any combination.

RTC-1 Realtime clock board. Two independent in-terrupts. Software programmable.

PCBD $30.00

EPM-1 1702A 4K Eprom card

PCBD $30.00

Special 2102AL-4 Vb Less Power than 21L02 series

ea $1.50; 32 $1.45; 64 $1.40

2102AL-2 250 NSEC $1.80 ea.; 32-63 $1.70; 64 +$1.60.

9080A AMD 8080A (Prime) $15.00

8212/74S412 Prime 3.50

8214 Prime 6.30

8216 Prime 3.95

8224 Prime 5.00

8228 Prime 6.95

8251 Prime 9.95

8255 Prime 9.95

1702A-6 AMD 402A Prime 3.95

TMS-6011 UART Prime 6.95

2513 Char Gen Upper Prime 9.95

2513 Char Gen Lower Prime 9.95

1702A Intel Not Prime 2.95

2708.5usec $16.95

2708 .65usec 12.95

m

419 Portofino DriveSan Carlos, California 94070

Please send for IC, Xistor

and Computer parts list.

8K BYTE RAM

with Factory Parts.450 NSEC $129.95

Order MB-6A with 210ZAL-4or WAMECO MEM-1 withMIKOS #1

250 NSEC $139.95

Order MB-6A with 210ZAL-2'sor WAMECO MEM-1 withMIKOS #3

8080A CPU $95.00

with 8 level vector interrupt.Order WAMECO CPU-1 &MIKOS #2

Check or money order only. If you are nota regular customer and your order is largeplease send either a cashier's check ora postal money order, otherwise there willbe a delay of two weeks for the check toclear. All items post paid in the U.S. Calif,residents add 6% tax. Money back 30 dayguarantee. We cannot accept returned IC'sthat have been soldered to. Prices subjectto change without notice. $10 minimumorder. $1.00 service charge on orders lessthan $10.

200

BYTE March 1978

Circle 73 on inquiry card.

CAlifoRNiA IncIustrIaI

Post Office Box 3097 B • Torrance, California 90503

Point Df SaleCflJTIPUTEfl

—■WMHjWIi ii i ■ i

*17S?°

iiiiiflii ijW^..

ttv

Manufactured by TRW Data Systems for the fast food industry. Designed for error-free

data entry. The operator simply blackens the appropriate box on a mark sense card

and Inserts it Into the form reader. The CPU searches Internal programable drum

memory for unit price and extends it by quantity, displaying the customer's grand

total on the LED module.

Memory system is capable of retaining over 40 register items. Accumulated data may

be pulled by a master computer.

This point of sale computer makes a super mark sense data terminal. The TRW 1336 is

shipped complete with cables and self-contained Mj& ±12v. power supply.

Brand new In factory cartons. Original cost $7,000. Weight 100 lbs., shipped freight

collect. Complete documentation not secured at press time.

CONNECTORS

P?

RS-232

DB25PI male plug & hood

vi'i "' gy

DB25S female

EdgeConnectors

100 PIN

IMSAI/ALTAIR

S-100 • GOLD PLATED • .125" CENTERS

Allair .140 row, solderlall $5.98 3/S16.50

Imsai .250 row, solderlall $4.98 3/$13.00

3 Level Wire Wrap .250 row... $4.98 3/$13.00

SPECIALSW/W same as above without ears$3.50 3/51072 (dual 36) W/W .156" centers... $2.50 3/$6

*i SCOtCli casset'tes >°-"Tk

110 for $45.

Diskettes

Please specifyIBM 3740 seriesor 32 sector.

also

minidisks

»550

Won't drop a BIT!

CALIFORNIAINDUSTRIAL

is an

Authorized

Dealer of

Scotch Brand

Dataproducts

2U02

low power

450 nS

iU=

Lowest PriceAnywhere

7400

.13

7442

7443

7402

7445

7446

7403

.19

7447

7404

.19

7448

7405

.19

7450

7406

19

7451

7407

25

7453

7408

7454

7409

25

7460

7410

.19

7470

7411

25

7472

7412

.35

7473

7413

7474

7475

7416

7476

7417

7420

7482

7465

74K

7427

748S

74B9

7429

7490

7433

7492

7437

7494

7439

39

7495

7440

.39

7496

.79

7497

3.99

74100

1.19

74107

74109

.49

74110

1,79

74116

74120

1.79

74121

.39

74122

74123

m

74125

.59

74)26

M

74128

74132

.99

74136

09

74141

74145

.99

74147

2.49

74148

1.99

74150

74151

.99

74153

-B9

74154

74155

.99

74156

129

74157

.99

74159

2.99

74160

74161

74162

1.49

74163

.99

74166

1.19

74167

4.99

74170

2.49

74173

1.49

74174

1.19

74175

.99

74176

.99

74177

.99

74192

74193

.99

CMOS

4001

25

14.95

24.9539.95

1702 A +95

82s23 295

82S123 2,95

2102 1.79

2102-1 1.89

21L02 1.19

250 nS. 1.49

CLOCK'S

5314 2.95

5316 4.95

5375 3.95

HEXADECIMAL KEYBOARD

Maxi Switch hexadecimal keyboards are designed lor 9 tjJ|™W,«

microcomputer Byslems that require 4-blt oulputIn standard hex code.Each assembly consists of 16 hermeti-cally sealed reed switches and TTL "orshoi" debuunce circuitry.Heilablo low Mellon acetal resinplungeis ace credited (or the smoothoperation and long life ol this premiumkeyboard.Requires single 4- 5 volt supply.

BARREL STOCK..

Test 'Em Yourself 'N Save

15 NE555 Timers, 100% functional

15 TRW Power Darlingtons, TO:3

15 2N3055 S, 2N3772 NPN power trans.

50 General Purpose TO:92 Transistors

100 Silicon Signal Diodes

SPECIALGENERAL INSTRUMENT ASCII Keyboard EncoderAY 5-3600 Prime but house marked only $4.95

TELETYPE MODEL 4 3

New Irom Teletype, the Model43 Is capable of printing 132 ASCIIcharacters per line. Send and receivedataat 10or30 char, per second. Key'board generates all 126 ASCII code combinalions. RS'232 Interface, same as the popularModel 33. Data sheet sent upon request. Maiturer suggested price $1377.00.

immediate delivery »1199

tel?

S24.8B

«<, ^UNIVACKEYBOARD

REGULATED

POWER SUPPLY

Delivers 5 volts at 8 Amperesalong with three other regu-lated outputs.

This used supply is sold "asIs," but we still feel that thisis the best buy you'll ever seeIn a regulated power supply.75 lbs., Schematics included.

Used H9.50

Shipped Freight Collect i

WetSttssWIin.

S-100 MOTHER

The Quiet Buss from California Industrial Isquality engineered. No short cut3 have been takento produce this mother board. Active terminationcircuitry prevents noise and crosstalk. Manufac-tured from entra heavy FR-4 epoxy glass. Features2 ounce double thlcknoss copper traces.

SLOT XV. /O

sirjoo

,tura tour 10OK potentio-fosistance proportional toHick Perfect for televisionroo and radio controlled

HlflnUflL GRflPHiTEDiSPLflV GEnERFVTDR

Modern technology has pioneeredunique characlcr punier Our M.Generator has I tic capabilily of plotlower case ASCII set Seltcomainec

Each unit is manufactured to strict tolerances as proscrby standards sat lorth by California Indusitial One freeevery order

developmenl ol IFal Guphile Display |ing Hie lull upper andr^or assembly allowsentered informal ion

$195

BRIDGE RECTIFIER

MOTOROLA 12 »mp. 50v.

990-1 27 Amp. >2.95

LMl41

s.OO

CALCULATOR

WRIST WATCH

OsalgnM lor lha on llm \\u oxocutlva, that Indi-vidual who has to maks Ihosa on the apoldoclslong.

Hand noma Qokl lonetoaluraa space age n

Inlo gratad circuit contains trie equivaieni ormora man 10.000 Irani I Mori.Ttlla LED wrisi walch displays dala. lima,elapse secorxja and also Igncltons as an etfltitdiQil calculator wllh memory. Inlormatlonsloed in memory can be recalled at any laterdate, even weeks C mantis. Use this memorye numbers, pnrtii.ig stall

»149.5°

PEAKERS

S69 >V°°

\4k MiniaturePerfect for TV games,alarmsystems, speech synthesizeror intercom. 8 ohms5"HiFidelity »2gg

R.F. Modulator

from Atari

'1395

Converts signal from APPLE XIand other vidio sources into TVfrequency. Complete with direc-tions and metal case. Assembled

Thumbwheel

Kl@^ switch

Ten position

BCD

'139...

E<c,

V

10 50

If 19 .89

TRIMMER

POTENTIOMETERS

2K 5K 10K50K,

5f.r*.98

20 50 100

16 < 14< 12 <

4002400640074008400940104011401?401340144015401640174010401940204021402240234024402540274028402940304032

300H

.79

301H

.39

301CN

302H

129

304 K

305H

.99

307H

307CN

.39

30SH

.99

308CN

309H

1.09

309K

.99

310H

1.19

310CN

1.19

311H

31 IN

99

312H

31BH

1.79

316CN

1.49

319CN

1.29

320K-5

139

320X-12

139

320K-1S

1.39

3201-5

320T-8

1.75

320T-12

1.75

320T-1B

1.75

320-24

1.75

324 N

1.79

339N

340K-5

195

340K-6

195

340K-12

1.95

340K-15

340K-18

1.95

340K-24

340T-5

179

340T-12

340T-I5

t.!9

34QT-24 1.79

350N .99

351CN .65

370H 1.29

370N 1.29

373N 3.19

377N 3*9

3B0N 1.39

38 IN 1.79

3B2N 1.79

NE555V .49

NE556 1.29

NE565H 1.49

NE565N 1.79

NE566N 1.25

703CH .45

709H .39

709N .39

710N .79

711H .39

711N .39

723H .55

723N .55

725H 3.49

733H 1.49

733N .99

739N 1.19

741N .09

747N ,79

7«H .39

748N .39

HUN 1.75

1458 .69MARTAY S-1013A

s4.98

$.69

Conductor Ft.

RIBBON WIREj

SPECTRA-STRIP

factory prime

2114/4045 IK b, 4 STATIC MEMORY

450nS. *ll?s SSOnS. »9?5

Transistors

•a. 10 50 100

2N2222A .20 .18 .10.152N3055 .69 .65 .59 .55MI305S .79 .75.69.652N3772 159 149 1.391292N3904 .15 .11.09.072N3906 .15 .11.09.07

Diodes

10 25 100

1N4002 100«. .08 06.051N4005 600». .10.08.07lN4148ii,nal .07.05.04

iurrtbo red aa. 10 25 100.ED'S hS.13.11.09

Power Adapter

6vdc,140mAU.397 dc, 1.4 A. 5.509vdc, 15mA. 1.199vdc,175mA. 1.95 f12vdc,600mA 2.951

*98

Output:12v.ct. 175mA.TRANSFORMER

Solar Cells

$1.19

10 100598 585

125mA. al .43V. Ideal lor poweringradio receivers or charging bat-teries.

RELAYS

SPOT MINIATURE

'l:«ea. 5115 104 .89

Coll 12 Volt dc.7 Amp Contacts

P. C. Board Mount

CAPACITORS

ELECTROLYTICS

aa. 10 50

80,000/10v. 395 3.49 2.954500/S0v.51»9 135 U9

1000/15v 555 49 .45anal

MiniatureSwitches

your choice- 10 50 100 la

*.aO 5.88 .81.73.66SPOT Miniature Toggles

7101 C&K ON-NONE-ON

7107 jbt ON-OFF(mnt.ON) I

7108 CK ON-(moment.ON) |

Rocker J8T DPDT

Rotary 3P-4-Pos.

Rotary 3P-6-Pos.

PushbMN.O.) 5.39ea.3/51

.1 disc.01 disc

5.12 .09 .07

.06 .05 .04 $]75

DIP Switch

10 25 100 I

SPST

DISCOUNT ' |

Wire WrapXenter

Heavyduty'groii ndedpower cord and matingchassis connectors.

FAST CHARGE

IC SOCKETS

Wire wrapaa. 25 50

low profileaa. 25 50

8

17< 16 15

14

37-36 35

18 17 16

16

38 37 38

19 18 17

24

99 93 85

36 35 34

40

169 155 139

63 60 58

S23.95 ,

s..l KVNARMp

.98 500 1,000 11,000

59. 515. 5105

V/SA 1

Circle 13 on inquiry car

Circle 88 on inquiry card.

-*-¥■—«4~~

SELECTR1C I/O TERMINALS (by GTE/Information Systems). Includes 8080interface plus software ASCII translation and I/O driver routines. 15" carriage,interchangeable type spheres & carbon/fabric ribbons. Built-in modem optional.

MODEL 5541 {IBM correspondence code, 2741 type terminal):MODEL 5550 (corres. code, with built-in cassette tape drive for

off-line data storage or use as memory typewriter).MODEL 5560 (ASCI I code, with cassette tape drive):

S 895

S1495$1495

IBM SELECTRIC TYPEWRITER with magnets, switches & magnet driver PCB(from GTE/IS Terminc! above). Includes instructions for 8080 printer/driverinterface (output only).

Typewriter mechanism complete, cleaned & adjusted S325

Aluminum case & Power Supply (+5V, + 12V, + 24V $75

MODEMS:

Send/receive Bcll-103 Type hy Vadic Corp. (requires+5V± 12V); 5 75Also 202-type modems, some with reverse Chanel transmissionand/or auto answer features.Telephone Coupler S 25

AMPEX MODEL TMX TAPE DRIVES with built-in NRZI formatter. 800BPI, 9 track, 12 IPS, 8" reel includes 8 bit CPU controller diagram and 8080interface instructions. Ideal for microcomputerist who wants back-up massstorage and access to IBM-type systems via standardized W mag tape. 575O

POWER SUPPLIES (from Diablo HyType I Terminal): pot adiustable, OVprotect. Inputs: 110 or 230 VAC: Outputs: +5V reg. <S> 30A; ±15V reg. @7A; -9V @ 5A (adjustable to -12V); unreg. +5V (adj. to + 12V): $75

PAPER TAPE READER (Addmaster 601-1): 50 cps, LED sensorsread 5-8 level tapes, bidirectional stepper motor, includes TTL serialinterface plus 8080 parallel interface instructions. Requires +5V &+24V:

INTERDATA Model One 8 Bit MINICOMPUTER, includes full frontpanel, 4K core memory (16K addressable), plug-in teletype port, plussoftware:

FORMS TRACTORS, variable width

MOORE FORMALINER for 15" IBM Selectrics

$90

$300

$50

• * *

Call or write for details, quantity discounts, orderforms. All orders shipped from stock — no back orders,no substitutions. All equipment is shipped insuredFOB Palo Alto within 7 days after check clears or CODorder is received. M/C & VISA cards accepted.

PACIFIC OFFICE SYSTEMS, INC.

2600 EL CAMIXO REAL, SUITE 302

PALO ALTO. CALIF. 9430G

Tel: (415) 321-3866

• • •

90 day warranty against defects in material or work-manship on all used equipment. Full documentationincluded PLUS interface instructions where indicated.Availability subject to prior sale. Prices may changewithout notice.

—+—*~~

GRAND GIVEAWAYVVVtf SALE //

/

< FR" > ELECTRONIC POCKETIA^/^\ CALCULATOR

With Any $10.00 Purchase (WITH COUPON)

Memory Modules We Slock

Computers We Stock

SSM MB7 200ns 16K 525

Industrial u Systems 8K 229

SPACEBYTE 16K Static 599

SSM MB7 450ns 8K 199

Vector Graphics 250ns 8K 269

Common DB SeriesConnector

Poly 88

Xitan I

Vector Graphics

Alpha Micro System

735.

769

619.

1495.

IMSAIS0L20Cromenco Z2Apple II (16K)Compucolor

FULL ASCII UPPER/LOWER CASE

COMPUTER KEYBOARDS

Used Guaranteed Working

Single Supply +5v @ 800 maSchematics IncludedBasic Keyboard $45.00Add: $5.00 for Upper Case Alpha$10.00 for Numeric Keypad$5.00 Misc. Function Switch$40.00 Metal Case w/bottom699. $45.00 Metal with Walnut Ends

1095. $1.50 Connector

595. $2.00 for 10 Extra Switches

1698.2750.

DB 9PDB 9SDB15PDB15SDB25PDB25SDC37PDC37SDD50PDD50S

11.101.501.50

2.252.253.252.954.903.906.50

101.001.401.402.002.003.102.754.503.506.00

Surplus TRW Power Supply original cost $100.00 pius

• GONE GOOFY PRICE

TEXAS INST Lo Profile Sockets

$5^

PinDIP Switches 8

We stock a com-plete line of 7400,74LS, 4000 CMOS

45678910

11.851.851.852.002.202.302.40

101.651.651.651.801.902.102.20

1416182022242840

1.30.25.27.408050505050

10

2.502.002.203.206.004.004.004.004.00

WEST COAST'S LARGEST SELECTION OFCOMPUTER RELATED HARDWARE

rM NM Mi M I coupon I H ■■ Hi 1CUT COUPON FOR COUPON ITEMS ■

COMPUTER COMPONENTS, INC.

I1.

4705 Artesia Blvd., Lawndale, CA 90260 (213) 370-4842

Lawndale, CA Store Open Mondays 10 AM - 7 PM

5848 Sepulveda Blvd., Van Nuys.CA 91411 (213) 786-7411

I

j

202

BYTE March 1978

Circle 137 on inquiry card.

•%?••••••••••••••••••••••••€••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• •••(?•

•_•» *;itiiiii«iiit«fi(ii**«***«««****'i*********************«*it««t*«t**iiti**«at««t**tiii*i* « • »•

••.:••■'• - ' ■■•■•■:>•

MOTOROLA QUAD OP - AMP

MC3401. PIN FOR PIN SUB.

FOR POPULAR LM 3900.

3 FOR $1

RECTIFIER SPECIAL

1.5 AMP 100PIV

EPOXY CASE AXIAL LEADS

15 FOR SI

FULL WAVE BRIDGE

4 AMP. 200 PIV.69«ea. 10 FOR $5.75

NOT ASSOCIATED WITH DIGITALRESEARCH OF CALIFORNIA, THESUPPLIERS OF CPM SOFTWARE.

16K E-PROM CARD

S-100 (l MSA 1/ALT AIR) BUSS COMPATIBLE

WO^'• DEALER INQUIRES INVITED

SPECIAL OFFER: Our 2708's (450 NS) are $12.95 when purchased with above kit

$69.95 (kit)

IMAGINE HAVING 16KOF SOFTWARE ON LINE AT ALL TIME!KIT FEATURES:

1. Double sided PC Board with solder mask and silk screen andGold plated contact fingers.

Selectable wait states. / USES

All address lines and data lines buffered!All sockets included.On card regulators.KIT INCLUDES ALL PARTS AND SOCKETS! (EXCEPT 2708's)

ADD $25 FORASSEMBLED AND TESTED

FULLY STATIC! $149.00 KIT

KIT FEATURES:

1. Double sided PC Board with solder mask and silk screen layout.Gold plated contact fingers.

2. All sockets included! S-l 00 (IMSA1/ALTAIR)

3. Fully buffered on all address and data lines. BUSS COMPATIBLE

4. Phantom is jumper selectable to pin 67.

5. FOUR 7805 regulators are provided on card.

8K LOW POWER RAM KIT!

PRICE WAR!

For a limited time only:Buy two 8K Kits for $129 ea.

Fully Assembled and Burned In —Blank PC Board With Documentation

Low Profile Socket Set —

Support IC's (TTL and Regulators) —

Bypass CAP's (Disc and Tantalums) —

USES

21L02-1

RAM'S.

$179.00

29.95

13.50

9.75

4.50

3W AUDIO AMPMODULE

Fully assembled and tested.With schematic. 4, 8 or 16OHMS.

$3.95 NEW!

MOTOROLA 7805RVOLTAGE REGULATOR

Same as standard 7805 except 750 MA

OUTPUT. TO-220. 5VDC OUTPUT.

$ .44 each 10 FOR $3.95

JUMBO RED LED'S

NewbyG.E. Like MV5024#SSL-22

6 FOR $1

25 FOR $3.75

POWER RECTIFIER

Stud Mount. 1N1204A. Hasan NCR House number. 12AMP 400 PIV.

75c ea. 4/$2.50

$&#* 4K STATIC RAM'S ^W.f

2114. The industry standard. 18 PIN DIP. Arranged as IK X 4. Equivalent toFOUR 21L02'sin ONE package! TWO chips give IK X 8, with data.

2 FOR $24 450N.S.! 8 FOR $85

450 NS! 2708 EPROMS 450 NS!

Now Full Speed! Prime new units from a major U.S. Mfg. 450 N.S. Accesstime. IK x 8. Equiv. to 4 1702 A's in one package!

Special Offer: $12.95 ea. when purchased with our

16K EPROM Kit.

$15.75 ea.

Z - 80 PROGRAMMING MANUAL

By MOSTEK, the major Z - 80 second source. The most detailed explanationever on the workings of the Z - 80 CPU CHIPS. At least one full page on eachof the 158 Z - 80 instructions. A MUST reference manual for any user of theZ - 80. 300 pages. Just off the press! A D.R.C. exclusive! $12.95

CMOS SPECIAL

CD 4001 -5 For $1 CD 4040 - $1 EachCD 4011 -5 For $1 CD 4042 - 2 For $ 1CD 401 3 - 3 For S 1 CD 4049 - 3 For $ 1

TERMS: ORDERS UNDER $15 ADD $ .75. NO C.O.D. WE ACCEPT VISA, MASTER CHARGE AND AMERICANEXPRESS CARDS. MONEY BACK GUARANTEE ON ALL ITEMS. TEXAS RESIDENTS ADD 5% SALES TAX.

Digital Research Corporation

P. O. BOX 401247 • GARLAND, TEXAS 75040 • (214) 271-2461

CALL FOR OUR CATALOG!

WE PAY POSTAGE!

■•»..»••••••••••.•.•»•»••••.••••••»•••.••»•••••••••••••••••••••••••••••••••............

•••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••a*

••••

Circle 135 on inquiry card.

BYTC March 1978 203

What's New?

PERIPHERALS

A Pad for Your Bytes

Digital Cassette Drives for Radio ShackTRS-80 and Altair (S-1 00) Bus

Summagraphics Corporation hasannounced the Bit Pad data tablet, a newinput peripheral designed specifically forsmall system users.

The unit is designed for fast datacollection of X, Y values. The small size(11 by 11 inches, 27.9 x 27.9 cm) andcompact design make the Bit Pad port-able and adaptable to a variety ofapplications. It can be interfaced to anymicrocomputer using its standard 8 bitparallel output.

Applications include medical treat-ment, opinion sampling, education, realestate, design, games, research, computeranimation and so on.

It can be used as a variable keyboardfor menu picking, for inputting data forinventory control or parts programming,etc. The price is $555.

Contact Summagraphics Corporation,35 Brentwood Av, Fairfield CT 06430,(203) 384-1344."

Circle 584 on inquiry card.

This cassette based mass storagesystem is offered in two versions forpopular personal computers. Picturedis the Alpha 1 system for Altair (S-100)bus computers. The controller cardplugs into the bus, controls up to fourdrives and will bootstrap from tapewithout the need for a read onlymemory monitor. A stand alone cassetteoperating system or a system withextended BASIC is available for theAlpha I. Prices start at $240. The CMSsystem is said to be plug compatiblewith the Radio Shack TRS-80 computer,with prices starting at $399. Eachcassette drive can store up to 500 Kbytes and can record or play backinformation at 780 bytes per second(data rate 6250 bps). Average accesstime to information anywhere on thecassette is 17 seconds. The units areavailable from MECA, 7026 OldWoman's Spring Rd, Yucca Valley CA92284, (714) 365-7686."

Circle 581 on inquiry card.

Video Graphics with Plotting Printer

A video graphic display and matchingprinter with plotting capabilities are nowavailable for the Wang 2200 series com-puters. The 2282 Graphics CRT has a12 inch (30.5 cm) diagonal screen with800 by 512 addressable dots. Vectorsare generated by turning on a series ofdots approximating a line. The 2231 W-3printer provides an accurate hard copyof a graphics image by printing strips of

800 dots by 8 dots. Alphabetic infor-mation can also be printed at 120characters per second. The 2282 is$3600 and the 2231 W-3 is $3800 fromWang Laboratories Inc, 1 Industrial Av,Lowell MA 01851, (617) 851-4111."

Circle 580 on inquiry card.

Vidicor

Camera

mM

,.•.

U'

°.J • 4

•

The modular C-1000 vidicon camerasystem has all handshake and controllines for computer interfacing built in.Standard building blocks are availableto perform commonly needed functionssuch as point tracking, area measurementand so on. High resolution (1000 TVlines) and low distortion (less than 0.2%)and drift (less than 0.05% per day) makethe unit appropriate for research andindustr-ial computer applications. Pricesstart at $3500 from Hamamatsu Corpor-ation, 120 Wood Av, Middlesex N)08846,(201) 469-6640."

Circle 582 on inquiry card.

Scientific Calculator Interface

This scientific calculator interfaceboard kit, which includes interfacesoftware for 8080 and 6800 basedsystems, is available in two versions,one for the Motorola Exorciser busand one for the Altair (S-100) bus.The board employs the MOS Tech-nology 7529-103 programmablecalculator chip, which features afull set of mathematical functions,factorials, and up to two levels ofparentheses in expressions. The kitis $99.95 from Mini Micro Mart, 1618James St, Syracuse NY 13204, (315)422-4467." .

Circle 583 on inquiry card.

204 BYTE March 1978

ELECTRONIC SYSTEMS

p.o. box 212 Burlingame CA 94010

(408)374-5984

fiuSffinUART&BAUDRATEGENERATOR

Part no. 101

• Converts serial to parallel andparallel to serial

• Low cost on board baud ralegenerator

• Baud rates: 110, 150,300, 600, 1200, and 2400

• Low power drain +5 volts and-12 volts required

• TTL compatible

• All characters contain a startbit, 5 to 8 data bits, 1 or 2 stopbits, and either odd or evenparity.

• All connections go to a 44 pingold plated edge connector

• Board only $12.00; with parts$35.00

8K

STATIC 0RAM

Part no. 300

• 8K Altair bus memory

• Uses 2102 Static memory chips

• Memory protect

• Gold contacts

• Wait states

• On board regulator

• S-100 bus compatible

• Vector input option

• TRI state buffered

• Board only $22.50; with parts$160.00

RS- 23*/ TTLINTERFACE

Part no. 232

• Converts TTL to RS-232, andconverts RS-232 to TTL

• Two separate circuits

• Requires -12 and +12 volts

• All connections go to a 10 pingold plated edge connector

• Board only $4.50; with parts$7.00

DC

POWER

SUPPLY

Part no. 6085 ■■«■

. Board supplies a regulated +5volts at 3 amps., +12,-12, and -5volts at 1 amp.

• Board has filters, rectifiers, andregulators

• Power required is 8 volts AC at3 amps., and 24 volts AC C.T. at1.5 amps.

• Board only $12.50

TIDMA

Part no. 112

• Tape Interface Direct MemoryAccess

• Record and play programs with-out bootstrap loader (no prom)has FSK encoder/decoder fordirect connections to low costrecorder at 625 baud rate, anddirect connections for inputs andoutputs to a digital recorder atany baud rate.

• S-100 bus compatible

• Comes assembled and testedfor $160.00

TAPE Part no. Ill

INTERFACE

• Play and record Kansas CityStandard tapes

• Converts a low cost taperecorder to a digital recorder

• Works up to 1200 baud

• Digital in and out are TTL-serial

• Output of board connects tomic. in of recorder

• Earphone of recorder connectsto input on board

• Requires +5 volts, low powerdrain

• Board $7.60; with parts $27.50

• No coils

Partno. 107

RFMODULATOR

• Converts video to AM modu-lated RF, Channels 2 or 3

• Power required is 12 volts ACC.T., or +5 volts DC

• Board $4.50; with parts $13.50

APPLE I

MOTHER

BOARD

Part no. 102

• 10 slots — 44 pin (.156) con-nectors spaced 3A" apart

• Connects to edge connector ofcomputer

• Pin 20 and 22 connects to X &Z for power and ground

• Board has provisions for by-pass capacitors

• Board cost $15.00

TELEVISIONTYPEWRITER

if* ga >fcs i m < «■ »ss • ■» • es

Part no. 106

• Stand alone TVT

• 32 char/line, 16 lines, modifi-cations for 64 char/line included

• Parallel ASCII (TTL) input

• Video output

• IK on board memory

• Output for computer con-trolled curser

• Auto scroll

• Non-distructive curser

• Curser inputs: up, down, left,right, home, EOL, EOS

• Scroll up, down

• Requires +5 volts at 1.5 amps,and-12 volts at 30 mA

• Board only $39.00; with parts$145.00

MODEM

Part no. 109

• Type 103

• Full or half duplex

• Works up to 300 baud

• Originate or Answer

• No coils, only low cost com-ponents l

• TTL input and output-serial

• Connect 8 ohm speaker andcrystal mic. directly to board

• Uses XR FSK demodulator

• Requires +5 volts

• Board $7.60; with parts $27.50

To Order:

Mention part number and description. For parts kits add "A" to part number. Shipping paid for ordersaccompanied by check, money order, or Master Charge, BankAmericard, or VISA number, expirationdate and signature. Shipping charges added to C.O.D. orders. California residents add 6.5% for tax.Parts kits include sockets for all ICs, components, and circuit board. Documentation is included withall products. Dealer inquiries invited. 24 Hour Order Line: (408) 374-5984. £21

Circle 44 on inquiry card.

BYTE March 1978

205

What's New?

PERIPHERALS

Wire Wrap Boards for LSI-11

Graphics for

Your SOL Computer

This kit adds a 128 horizontal by 48vertical point graphic display capabilityto your SOL computer or VDM-1 videodisplay board. A piggyback printedcircuit board mounts directly on theSOL or VDM-1 board to add graphics.Software, supplied on a SOL CUTScassette and paper tape, provides: adriver routine to manipulate individualpoints, links to the SOL's BASIC 5,demonstration plotting programs and ananimation program for John Conway'sgame of Life. The kit is available for $50from KEA Micro Design, POB 6531Station A, Toronto, Ontario CANADAM5W 1X4."

Circle 604 on inquiry card.

Breadboarding Card forAltair (S-100) Bus

This breadboarding card makes itespecially convenient to add experi-mental circuitry to an Altair (S-100) bus

compatible computer. The board plugsinto the bus (with offset contacts toprevent incorrect insertion) and pro-vides breadboard access to every signal,divided into address, data and controlsections. Voltage regulators for +5 V,+12 V and -12 V are provided as wellas points for obtaining unregulatedvoltage. 22 gold plated contacts areprovided on the other side of the cardfor external connections. Three SK-50breadboarding sockets, each with 32pairs of live common contacts and aseries of common bus strips are includedas well as a breadboarding area for the22 card edge contacts. The card is pricedat $75 from E & L Instruments Inc, 61First St, Derby CT 06418, (203)735-8774."

Circle 605 on inquiry card.

A Plethora ofPeripheral Boards

A variety of peripheral boardsare now available for the do-it-your-selfer, including a universal asynchro-nous receiver transmitter (UART) board(pictured), a full duplex, 300 bpsmodem, a TTL compatible RS232Cinterface, a Kansas City standardcassette tape interface, a 32 or 64character per line video display board,and an RF modulator board withpower supply to interface a videosignal to a television set. Also avail-able are an 8 K byte static memoryboard lor the Altair (S-100) bus, anda mother board, 8 K memory board,and serial IO board for Apple Icomputers. All circuit boards comewith complete instructions and partslists, and are designed to use inexpen-sive, easy to find parts. Parts kits andfully assembled units are also available.Prices for the boards range from $5 tounder $40, from Electronic Systems,POB 212, Burlingame CA 94010, (415)573-7788."

Circle 606 on inquiry card.

These wire wrap boards can be usedto build your own memory and inputoutput systems for the LSI-1 1 com-puter. Each board, designed for insertionof wire wrap pins, can accommodateabout 130 standard 14 pin and 16 pindual in line packages, plus passivecomponents. A ground shield is providedon one side of the board. The WW-11.5half size version sells for $35 in singlequantities, while the WW-11 full sizeversion is $75, from Artec ElectronicsInc, 605 Old County Rd, San Carlos CA94070, (415) 592-2740."

Circle 607 on inquiry card.

Space Saving Terminal

The Transactor I data terminalconsists of a single line 32 charactergas discharge display with a 5 by 7 dotmatrix for easy reading, and a 53 keyTeletype style keyboard. It can beattached to almost any computer, withan RS232 or 20 mA current loop inter-face. Switches allow the user to selectthe operating mode including 110 to9600 bps data rate, full or half duplex,even, odd or no parity, five to eightdata bits, and one or two stop bits.

Lightweight and small, the Trans-actor is housed in an attractive andsturdy aluminum case that measuresonly 6 by 15 by 11 inches (15.2 by38.1 by 27.9 cm). A stylized moldedcase is available. Price of the standardTransactor I in quantity is $595, fromComputerwise Inc, 4006 E 137th Tcr,Grandview MO 64030, (816) 765-3330."

Circle 608 on inquiry card.

206

BYTE March 1978

PLETE SAJI

jJN IS OUR GUARANTEE VOUR COMPLETE SATISFACTION IS OUR GUARANTEE YOUR COMPLETE SATISFACTION

SEND TODAY FOR CATALOG OF COMPLETE IC AND KIT LISTING

HUGE DISCOUNTS!

Savings up to 70% on inajor brand !C parts and computer kits.

74L$00 TTL

74LS00 $

74LS02

74LS04

74LS08 $

74L$10

74LS14

74LS20

74L$21

74H22

74LS30

74LS32

74LS37

74LS38

74LS42

74LS47

74LS48

74LS73

74LS74

74L575

74LS76

74L$86

74LS90

74LS92

74LS9374LS10974LS11274LS11374LS11474LS12574LS12674LS13274LS13874LS13974LS15174LS15374L$154 1.0074LS157 S 6274LS160 .8274LS161 .8274LS162 .8274LS163 .8274L$164 .9874LS174 .7574LS175 .7974LS190 .9074LS191 .90

.52.36.36.3636.46.46.75.70.70.65.66

74LS192 .90

74LS196 .80

74LS197 .80

74LS221 1.06

74LS257 .71

74LS258 .70

74LS266 .26

74LI283 .72

74LS365 .55

74LS366 .55

74LS367 .55

74LS368 .55

74LS386 .39

81LS95 .77

81LS96 .77

81LS97 .77

81LS98 .77

KITS

33.00

28.0028.00

WAMECO

S-100 PC. Boards8K RAMZ-80 CPU12-Slot Mother

BoardITHACA AUDIOS-100 P.C. Boards8K RAMZ-80 CPUSOLID STATE MUSICS-100 Kits & Bare BoardsMB-3 2K/4K EPROMUses 1702A EPROMS

Kit w/oEPROMS 59.95MB-4 4K STATIC RAM

Kit 95.00

Bare Board 25.95

MB6A8K STATIC RAM

Kit $179.95

Bare Board 25.95

MB7 16K STATIC RAM

Kit 435.00

Bare Board 25.95

MB8 8K/16K EPROM

Uses 2708's

Kit Less EPROMs 75.95

Circle 54 on inquiry card.

VISA

o»;***zc*fe

to

°s/.

682068508212821482168224822882268238

CMOS

BOOKS

Prime Factory Kit

90 Day Guarantee

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Cybercom div. Solid State Music

ony $375.00

Home Computers; 210 Questionsand Answers; Volume 1: Hardwareby Rich Didday 225 pp.Home Computers: 210 Questionsand Answers; Volume 2: Softwareby Rich Didday 175 pp.Calculator Users' Guide andDictionary by Charles Sippl 444 pp.Microcomputer Dictionary andGuide by Charles Sippl 704 pp.Introduction to BASICby Jeffrey Morton 200 pp.Analysts and Design of DigitalCircuits and Computer Systemsby Paul ChirlianFinite State Fantasiesby Rich Didday 50 pp.

LM 309HLM 309KLM 320H-5LM 320H-6LM 320H-8LM 320H-12LM 320H-15LM 320H-18LM 320H-24LM 320K-5LM 320K-6LM 320K-8LM 320K-12LM 320K-15

74XX

REGULATORS

□ Cash

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TELEPHONE ORDERS:Call (213) 641-4200

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Satisfaction 100% Guaranteed

California Residents Add 6%Sales Tax

Note: Minimum Order $10.00, 5% Discount over $100.00

7441744274437444744574467447744874507451745374547460747074727473747474757476747974807481748274837485748674897490749174927493749474957496

741U97412174122

741237413274141741457415074151741537415474157741617416374164741657417074173741757417574176741777418074181741907419174192741937419574221742517436574366743677436B

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IC MASTER

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What's New?

PERIPHERALS

Prototyping Package for 8080 Systems

Designers can quickly construct cus-tom interface systems using the BLC80/10 board level computers with theaid of this prototyping package. TheBLC 80P package includes a BLC 80/10computer board with 1 K bytes of

programmable memory, a system moni-tor in 2 K bytes of read only memory,and an additional 2 K bytes of blank2708 type programmable read onlymemory. A prototyping board withspace for 114 16 pin sockets or anequivalent mix of other sockets is alsoincluded. The boards are housed in afour slot card cage which also serves asa backplane and system bus. Two powercables are supplied as well as two 50conductor ribbon cables for connectionto external circuits. The BLC 80/10 hasjumper selected options for RS232 orcurrent loop interfaces, and cables aresupplied for a CRT terminal and for aTeletypewriter. Documentation includesa hardware reference manual, user'sguide and schematics. The BLC 80P ispriced at $878 from National Semicon-ductor Corp, 2900 Semiconductor Dr,Santa Clara CA 95051, (408)737-5166."

Circle 610 on inquiry card.

Multifunction Floppy Controllerfor LSI-11

Several common functions have beencombined in this dual width interfacecard for the LSI-11. The interface con-trols up to three Shugart SA-400 mini-floppy drives, provides a direct memoryaccess dynamic memory refresh con-troller, and includes sockets for up to4 K or 8 K 16 bit words of program-mable read only memory. The floppycontroller performs several functionsautomatically including track seek andverify, cyclic redundancy code gener-ation and checking, and drive motortimeout shutoff. The memory socketshold up to 4 K of 2708 type chips or upto 8 K of 2716 type chips. The -5 Vpower supply for these chips is generatedon the board. Provisions have been madefor mapping the LSI-11 bootstrapaddresses onto these chips or ontofusible link read only memories. TheMDC11 combined board is priced at$510, the minifloppy drives at $325,the MREF11 dynamic memory refreshcontroller alone is $195 and thePROM11 read only memory sectionalone is $170, from Andromeda SystemsInc, 14701 Arminta St J, Panorama CityCA 91402,(213) 781-6000."

Circle 673 on inquiry card.

Printer for Motorola Exorciser

Printer Offers 6 or 12 Charactersper Inch

Designed for use with the MotorolaExorciser or Micromodules, this impactprinter produces lines of up to 80 5 by 7dot matrix characters at a speed of 110characters per second (about 65 lines perminute). The print head moves in bothdirections on 8.5 inch (21.6 cm) wideroll paper and uses a conventionalTeletype ribbon. A peripheral interfacemodule and interconnecting cable areincluded with the printer, making thedevice functionally equivalent to a

Centronics 306 type printer. The MDOSand EDOS operating systems for theExorciser provide drivers and commandsfor the new device. A 230 V 50 Hzversion is available for European users.The EXORprint printer is $1725 fromMotorola distributors or from themanufacturer. Contact Motorola

Semiconductor Products Inc, TechnicalInformation Center, POB 20924,Phoenix, AZ 85008, (602) 244-6815."

Circle 61 2 on inquiry card.

The DP-1000 series printers feature adot matrix impact printing elementcapable of printing 64 alphanumericand special characters in 40 charactersper line at 1.25 lines per second onstandard single or multiple copy paperrolls. Three RS232C configurationsallow convenient interfacing to mostminicomputers, modems and tele-printers. Data rates from 110 to 2400bps are available. Single or double widthcharacters are selected with an externalcontrol line, allowing either 6 or 12characters per inch to be intermixedon a line. Prices start under $700 withsubstantial quantity discounts, fromAnadex, 9825 DeSoto Av, ChatsworthCA 91311, (213) 998-8010."

Circle 61 5 on inquiry card.

208

BYTEMarcli 1978

DIODES/ZENERS

SOCKETS/BRIDGES

TRANSISTORS, LEDS, etc.

1N914

100v 10mA .05

8-pin pcb .25 ww .45

2N2222 NPN (Plastic .10

.15

1N4005

600v

1A .08

14-pin pcb .25 ww .40

2N2907 PNP

.15

1N4007

lOOOv

1A .15

16-pin pcb .25 ww .40

2N3906 PNP

.10

1N4148

75v 10mA .05

18-pin pcb .25 ww .75

2N3054 NPN

.35

1N753A

6.2v

z .25

22-pin pcb .45 ww 1.25

2N3055 NPN 15A 60v

.50

1N758A

10v

z .25

24-pin pcb .35 ww 1.10

T1P125 PNP Darlington

.35

1N759A

12v

z .25

28-pin pcb .35 ww 1.45

LED Green, Red, Clear

.15

1N4733

5.1v

z .25

40-pin pcb .50 ww 1.25

D.L.747 7 seg 5/8" high corn-anode 1.95

1N5243

13v

z .25

Molex pins .01 To-3 Sockets .45

XAN72 7 seg com-anode

1.50

1N5244B1N5245B

14v15v

z .25z .25

2 Amp Bridge 100-prv 1.2025 Amp Bridge 200-prv 1.95

FND 359 Red 7 seg corn-cathode

1.25

CMOS

- T T L -

4000

.15

7400

.15

7473 .25

74176 1.25

74H72 .55

74S133

.45

4001

.20

7401

.15

7474 .35

74180 .85

74H101 .75

74S140

.75

4002

.20

7402

.20

7475 .35

74181 2.25

74H103 .75

74S151

.35

4004

3.95

7403

.20

7476 .30

74182 .95

74H106 .95

74S153

.35

4006

1.20

7404

.15

7480 .55

74190 1.75

74S157

.80

4007

.35

7405

.25

7481 .75

74191 1.35

74L00 .35

74S158

.35

4008

.95

7406

.35

7483 .95

74192 1.65

74L02 .35

74S194

1.05

4009

.30

7407

.55

7485 .95

74193 .85

74L03 .30

74S257 (8123)

.25

4010

.45

7408

.25

7486 .30

74194 1.25

74L04 .35

4011

.20

7409

.15

7489 1.35

74195 .95

74L10 .35

74LS00

.35

4012

.20

7410

.10

7490 .55

74196 1.25

74L20 .35

74LS01

.35

4013

.40

7411

.25

7491 .95

74197 1.25

74L30 .45

74LS02

.35

4014

1.10

7412

.30

7492 .95

74198 2.35

74L47 1.95

74LS04

.35

4015

.95

7413

.45

7493 .40

74221 1.00

74L51 .45

74LS05

.45

4016

.35

7414

1.10

7494 1.25

74367 .85

74L55 .65

74LS08

.35

4017

1.10

7416

.25

7495 .60

74L72 .45

74LS09

.35

4018

1.10

7417

.40

7496 .80

75108A .35

74L73 .40

74LS10

.35

4019

.60

7420

.15

74100 1.85

75110 .35

74L74 .45

74 LS11

.35

4020

.85

7426

.30

74107 .35

75491 .50

74L75 .55

74LS20

.35

4021

1.35

7427

.45

74121 .35

75492 .50

74L93 .55

74LS21

.25

4022

.95

7430

.15

74122 .55

74L123 .55

74LS22

.25

4023

.25

7432

.30

74123 .55

74H00 .25

74LS32

.40

4024

.75

7437

.35

74125 .45

74H01 .25

74S00 .55

74LS37

.35

4025

.35

7438

.35

74126 .35

74H04 .25

74S02 .55

74LS40

.45

4026

1.95

7440

.25

74132 1.35

74H05 .25

74S03 .30

74LS42

1.10

4027

.50

7441

1.15

74141 1.00

74H08 .35

74S04 .35

74LS51

.50

4028

.95

7442

.45

74150 .85

74H10 .35

74S05 .35

74LS74

.65

4030

.35

7443

.85

74151 .75

74H11 .25

74S08 .35

74LS86

.65

4033

1.50

7444

.45

74153 .95

74H15 .30

74S10 .35

74LS90

.95

4034

2.45

7445

.65

74154 1.05

74H20 .30

74S11 .35

74LS93

.95

4035

1.25

7446

.95

74156 .95

74H21 .25

74S20 .35

74LS107

.85

4040

1.35

7447

.95

74157 .65

74H22 .40

74S40 .25

74LS123

1.00

4041

.69

7448

.70

74161 .85

74H30 .25

74S50 .25

74LS151

.95

4042

.95

7450

.25

74163 .95

74H40 .25

74S51 .45

74LS153

1.20

4043

.95

7451

.25

74164 .60

74H50 .25

74S64 .25

74LS157

.85

4044

.95

7453

.20

74165 1.50

74H51 .25

74S74 .40

74LS164

1.90

4046

1.75

7454

.25

74166 1.35

74H52 .15

74S112 .90

74LS367

.85

4049

.70

7460

.40

74175 .80

74H53J .25

74S114 1.30

74LS368

.85

4050

.50

7470

.45

74H55 .25

40664069

.95.40

7472

.40

4071

.35

LINEARS, REGULATORS, etc.

4081

.70

8266 .35

LM320K5 (7905) 1.65

LM340T24 .95

LM723

.50

4082

.45

MCT2 .95

LM320K12 1.65

LM340K12 2.15

LM725

1.75

8038 3.95LM201 .75

LM320T5 1 65

LM340K15 1.25

LM739

1 Kn

9000 SERIES

i ■ i v j .. j „" e..; | . i | ,\j\j

LM320T12 1.65

LM340K18 1.25

LM741 (8-141.25

9301

.85

LM301 .25

LM320T15 1.65

LM340K24 .95

LM747

1.10

9309

.35

LM308(Mini) .75

LM339 .95

LM373 2.95

LM1307

1.25

9322

.85

LM309H .65

7805 (340T5I .95

LM380 .95

LM1458

.95

95H03

.55

LM309K (340K5) .85

LM340T12 1.00

LM709 (8,14 PIN) .25

LM3900

.50

9601

.75

LM310 1.15

LM340T15 1.00

LM711 .45

LM75451

.65

9602

.50

LM311D (Mini) .75LM318 (Mini) .65

LM340T18 1.00

NE555NE556NE565

.50.95.95

MEMORY CLOCKS

74S188I8223) 3.001702A 6.95MM5314 3.00MM5316 3.502102-1 1.75

INTEGRATED CIRCUITS UNLIMITED

NE566NE567

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7889 Clairemont Mesa Boulevard, San Diego, California 92111

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TMS6011 6.958080AD 15.008T13 1.508T23 1 Kn

All orders shipped prepaid No minimum Total Order DeductOpen accounts invited COD orders accepted $iro $300 10%Discounts available at OEM Quantities California Residents add 6% Sales Tax $301 $1000 15%

8T24

2.00

All IC's Prime/Guaranteed. All orders shipped same day received. 3>iuuu - Up

20%

2107B-4

4.95

24 Hour Toll Free Phone 1-800 854 2211 MasterCharge / BankAmericard / AE

Circle 57 on inquiry card.

BYTE March 1978

209

What's New?

SOFTWARE

C Compiler Available for PDP-11,Planned for 8080

A compiler for the structured pro-gramming language C is now available forthe PDP-11, and an 8080 version of thecompiler is expected in early 1978.Because of its structured, table drivendesign, the compiler can be easily modi-fied to produce object code for a newcomputer, thereby ensuring a consistentdefinition of the C language from oneimplementation to another. The com-piler is said to generate code efficientenough to be used in real time systemprogramming environments. A combinedtutorial and reference manual affordseasy access to the C language. The pres-ent compiler runs under the RSX oper-ating system and is planned for otheroperating systems. It generates opti-mized code for each model of thePDP-11 from the 11/20 to the 11/70.The compiler is available on a leasebasis for $11,575 from Yourdon Inc,1133 Avenue of the Americas, NewYork NY 10036."

Circle 585 on inquiry card.

Learn BASIC from Your Computer

This 6800 based package is designedto coach and prompt you to learnBASIC commands and programmingtechniques. Part I presents fundamentalBASIC commands, while Parts II and IIIteach techniques of character string for-matting, and reading and writing char-acters to cassette using BASIC andMIKBUG. Each part is priced at $13.95,with discounts for combinations of thethree parts. An introductory samplerpackage is also offered for $6.95. Thepackages are supplied on cassette usingthe "Kansas City" recording standard,which can be read by the SouthwestTechnical Products AC-30 interface, andwill run on a 12 K byte 6800 sys-tem. Contact Computerware SoftwareServices, 830 First St, Encinitas CA92024.■

Circle 586 on inquiry card.

New Business Forms forSmall Computers

Computer forms designed forhobbyists and small systems users havebeen introduced by the Kenmor Com-pany. Invoices, statements and otherstock items made specifically for micro-computers are available in quantities ofup to 5,000 sets. Company names orlogos can be imprinted, and customforms can also be supplied. The pro-duct line is aimed at small businesses,hobbyists, physicians, dentists, accoun-tants, etc, who wish to update theirbilling and record systems.

Contact Kenmor Corporation, 675McLean Av, Yonkers NY 10704, orcall Roberta Fink at (914) 965-3006."

Circle 587 on inquiry card.

Management Problem Solving Library

Here's a library of programs for fi-nancial analysis complete with a twoyear updating service. Each program inthe library is described in a user manual,and is said to be tested in a user environ-ment prior to distribution. Libraryupdates are issued quarterly and can beobtained for a nominal copying fee. Theprograms include present and futurevalue problems, loan amortization prob-lems, depreciation schedules for variousdepreciation methods, a complete realestate investment package, a cashbudgeting program, and an elementaryfloat analysis of check clearing. Ver-sions are available for MITS Disk Ex-tended BASIC and for North StarBASIC. The programs are availablefrom Business Computer Systems, 216Collier Dr, Springfield IL 62704,(217) 787-3448."

Circle 588 on inquiry card.

Editor Lets You Create New Commands

ATE is an 8080 assembler, texteditor and cassette operating systemdesigned especially to run with the allpurpose IO board from Morrow's Micro-Stuff. The editor borrows features suchas text addressing and programming ofloops and subroutines of editing com-mands from classical text editors likeQED and TECO. The assembler canhandle programs larger than memory,can produce object code listings in anynumber base, and allows editing of theobject code. ATE fits in 4 K bytes andruns comfortably in 8 K bytes of pro-grammable memory. Written by GaryFitts, ATE is offered on a Kansas Citystandard cassette tape for $24.95 fromThinker Toys, 1201 10th St, BerkeleyCA 94710, (415) 527-7548."

Circle 589 on inquiry card.

Build Your Own Software System

The System Kit is a collection inbook form of 8080 assembly languageprogram modules and narrative textdescribing module functions and inter-facing conventions (for parameter pass-ing and register and memory use). Itconsists of building blocks for an oper-ating system, a runtime linker and aminiloader which enables you to con-struct a custom system of your owndesign. The modules are grouped intoa nucleus and four surrounding layersor "shells." Functions provided by themodules include clock, IO and consolehandling, memory and queue manage-ment, event processing and timesharedtask scheduling, and similar operations.The System Kit is $50 from La ForgeEnterprises, POB 410, Boalsburg PA16827, (717) 564-2440."

Circle 592 on inquiry card.

MIKADOS Adds Disassembler

The Mini Instant Keyboard As-sembler, Debug and Operating System(MIKADOS) now includes a disassembleras well. The assembler translatesassembly code directly to machine lan-guage as it is entered, resolving jumpsand relative branches, and the disas-sembler produces a pseudo assemblycode listing of a machine language pro-gram in memory. Other features includesetting and clearing of breakpoints andASCII and hexadecimal IO. The disas-sembler is offered to existing MIKADOSusers for $5. The whole package fits in 3K bytes of memory, comes with a 28page user manual and a 90 day limitedwarranty against bugs, and costs $17.95from Inpro Micro Systems, POB 7776,Van NuysCA 91409."

Circle 590 on inquiry card.

STATEMENT

CHARGES AND PAYMENTS MADE

AFTER THIS DATE WILL APPEAR

^ON YOUR NEXT STATEMENT.

ACCOUNTNO.

CURRENT TRANSACTIONS

' PREVIOUS *BALANCE W

H

DATE

NUMBER

DESCRIPTION

CHARGES

CREDITS

CURRENT

OVER 30 DAYS

OVER 00 DAYS

OVER 00 DAYS

OVER 120 DAYS

OFACC

r.

/

AMOUNTDUE

210

BYTt" March 1978

The Thinking Computer: Mind Inside

Matter by Bertram Raphael. Artificial intel-ligence, or Al, is the branch of computerscience concerned with making computers"smarter." It is a growing, vital field that is,unfortunately, the subject of much popularmisunderstanding. The Thinking Computer:Mind Inside Matter is a lucid introduction toAl that does much to overcome this mis-understanding. With a minimum of technicaljargon, this book discusses the capabilitiesof modern digital computers and how theyare being used in contemporary Al research.It discusses the progress of Al, the goals,and the variety of current approaches tomaking the computer more intelligent.$6.95.

The thinking con*

■ ,;! ... ,'

.

■

m ■

SB

■

RMffl

Projects in Sight, Sound, & Sensation

by Mitchell Waite. Dedicated "to all spacecowboys." Detailed theory and practice ofseven fascinating amateur electronics proj-ects, along with a complete and detailed ap-pendix on how to make PC boards. Theprojects included in this book are: TheSyntheshape, an art generator that can beused to generate innumerable complex andbeautiful patterns on the screen of an oscil-loscope. An electronic music box that willplay over 3000 possible melodies when thelid is lifted. A way to control muscle tensionexplained in chapter 4. A muscle-wave bio-feedback monitor can be used to achievedeep relaxation. The laser-light show trans-fers light into fascinating patterns in a dark-ened room. Other projects include a Kirliancamera, a digital ESP machine, and neon-light randomizer. $5.25.

MindMassagersfrom BITS

The Great International Math On Keys

Book, from Texas Instruments. Do youneed a numerical algorithm for calculatingexchange rates in a hotel on a foreign trip?Or figuring those mysterious "points" whenfacing the sanctimonious charisma of abanker at mortgage time? This book is acompendium of simple explanations andstep by step procedures for accomplishingnumerical solutions to numerous com-monly encountered situations in daily life.Each entry is characterized by a statementof the problem, including the elements oftheory required, and the keystrokes neededto solve the problem on an algebraic entrycalculator. This is an invaluable sourcebookof information for the person who is in-clined to manipulate numbers. $4.95.

!4»)

mmm

*«==

! How to Solve Problems by Wayne A

Wickelgren. When confronted by a problem,many of us spend more time puzzling overhow to solve it than in actually doi ng so. Thisbook analyzes and systematizes the basicmethods of solving mathematical problems.The methods are described in terms of amodern theory derived from research incomputer simulation of thinking. Examplesillustrating these methods include chessproblems, logical puzzles, and railroadswitching problems frequently encounteredin science and engineering. Whether your in-terest in solving problems is professional,recreational, or both, you will find this ahelpful book. $6.50 softcover.

CHESS SKILL

IN HAM ■•'■■

:*■

Chess Skill in Man and Machine edited

by Peter W Frey. This is a most fascinatingbook, concerning itself with the when, how,and why of computer chess. The when de-scribes past ACM computer chess tourna-ments, with the details of more than a doz-en games. The how consists of the basics ofboth human chess skill and computer chesstheory. It includes a detailed description ofthe best computer chess program to date(Northwestern University's CHESS 4.5), anend game program called PEASANT, and ofvarious search strategies and heuristic com-puter chess theory which should enable oneto write his own chess program. The bookends with the why concerning the contribu-tions, now and in the future, of computerchess to understanding artificial intelligence,human intelligence, and learning. The onlydifficulty for the hobbyist's computer chessprogram is the need for a large computer forthe fast processing of search strategies andlarge core storage for the program and itsresults. $14.80 hardcover.

DIAL YOUR BANK CARD ORDERS ON THE BITS TOLL FREE HOT LINE: 1-800-258-5477.

In New Hampshire, call: 924-3355 Check Payment method:

Send to: ^A IV'V crjeck is enclosed

BITS, Inc. ^^ * Rill my MCI Nn / / / Fxp date

70 Main Street bSb SSSm Bill my BAC No L L L Exp. date.

Peterborough NH 03458

Name

Address

Total for all books checkedPostage, 50 cents per book for

. books

$_$-

Citv

State

Zip Code

Overseas, 75 cents per book for.

.books

Grand Total

Signature

You may photocopy this page if you wish to leave your BYTE intact.

Prices shown are subject to change without noticeAll orders must be prepaid.

Circle 10 on inquiry card.

BYTE March 1978

211

(m

DDCAn BOARD Each ki' Witafos 350 wires'uhi_j-iu/ uwni \\j cu) (0 (4 d|„eran, ,Bnflths

JUMPER WIRE KIT'Tl»--artmasna

the leads are bent 90' toreasy insertion.

Wire length Is classifiedby color coding

All wire is solid linned 22gaoge with PVC Insulation.

The wires come packed inJK1 $10.00/kit a convenient plastic bo<

HCflPlaf CT Mat6S W',fl ,W0 r0WS 0f ,025' ^ 0FoUuIaC I dia. posts on patterns of .100"

II ||ar\t-Qn centers and shielded receptacles.JUtVlr CnO [Droi)e access holes in back. Choice

of 6" or 18" length.Part No. No. of Contacls Length Price

924003-18R 26 18" $ 5.38 ea.924003-06R 26 6" 4.78 ea.

924005-18R 40 18" 8.27 ea.

924005-06R 40 6" 7.33 ea.

924006-18R 50 18" 10.31 ea.924006-06R 50 6" 9.15 ea.

rTSJ HIMPFR Solder "> Pc boards for instant

Hjf J U IVI r C n plug-in access via socket-connector

UCAnCDC jumpers. .025" sq. posts. Choice

ntAUtnO of straight or right angle.

Part No.

923863-R923873-R923865-R923875-R923866-R923876-R

No. of Posts Angle

2626

404050

50

straightright anglestraightright anglestraightright angle

Price

$1.28 ea.1.52 ea.1.94 ea.2.30 ea.2.36 ea.2.82 ea.

H INTRA-CONNECTOR

Provides both straight and right angle functions. Mateswith standard .10" x .10" dual row connectors (i.e. 3m, Ainsley,etc.) Permits quick testing of inaccessible lines.Part No.: 922576-26 Ho. ot contacls: 26 Price $6.90 ea.

H INTRA-SWITCH

Permits instant line-by-line switching for diagnostic or QAtesting. Switches actuated with pencil or probe tip. Mates withstandard .10" x .10" dual-row connectors. Low profile designSwitch buttons recessed to eliminate accidental switching.Pari No.: IS-26 No. of contacls: 26 Price £13.30 ea.

"^CRYSTALS ijgf-

— ,""*-•*- THESE FREQUENCIES ONLY ~^%*Pltl #"" " Frequency Caie/Style PriceCY1A 1 000 MH! HC33/U S5 95

CY2A 2.000 MH; HC33.'U S5.95

ICY2 01 2.010 MHl HC33/U

CY3ACY7ACY12ACY14ACY19ACY22ACY30B

4.000 MH!

5.000 MH;10 000 MH!14 31818 MH!18 000 MH!20 000 MHz32.000 MHz

HC187UHC18/U

HCia.'U

HC1BUHC18/UHCIB/UHC18/U

SMIS4.95S4.95S4.95

S4.95S4.95S4 95S4.95

CONNECTORS

PRINTED CIRCUIT EDGE-CARD

.156 Spacing-Tin-Double Read-Out

Bifurcated Contacts — Fits .054 to .070 PC Cards

15/30 PINS (Solder Eyelet) $1.95

18/36 PINS (Solder Eyelet) $2.49

22/44 PINS (Solder Eyelet) $2.95

50/100 PINS (Wire Wrap) $6.95

50/100A moo Spacing) PINS (Wire Wrap) $6.95

25 PIN-D SUBMINATURE (RS232)

DB25P PLUG $3.25

DB25S SOCKET S4.95

y." mounting holes

SWITCHES

JMT121 SPDT on-oH-on SI .95 11.43

mntu c JMT123 SPDT on-nane-on 1.65 1.21

, ^ . , , JMT221 DPDT on-oll-on 2.55 . 1.87

(sub-minature) JUT223 DPDT on-none-oii 2.15 1,58

MPC121 SPDT on-ofl-on $2.05

~~fc TOGGLE MPC123 SPDT on-nnne-on 175

pjjj (Printed Circuit) MPC221 DPOT on-off-on 2.65

**W MPC223 DPDT on-none-on 2.25

SPDT maintainedSPDT momentary

5i PUSH BUTTON MS102 DPST momentary open .35!■ Minature MS103 SPST momentary closed 35

8 pin dip 4 switch 1.75 1.65

14 pin dtp 7 switch 1.95 1 85

16 pin dip 8 switch 2.25 2.15

1/16 VECTOR BOARD

Pail No

64P44 062XXXP1G9P44 062XXXP64P44 062WE84P44 062WE169P44 062WE169P84 062WE169P44 062WEC1

INSTRUMENT/CLOCK CASE

Injection molded unit.Complete with red bezel., Wx 4" X1-9/16".

V_ $3.95 ea

MICROPROCESSOR COMPONENTS

82128214821682248228

B080A2650P6Q85

2504251825192522252425252527252925322533

CPU

8 Bit Input/OutputPriority Interrupt ControlBi-Directional Bus DriverClock Generator/Driver

$16.00 CDP1802 CPU

4.95 MC6800 8 Bit MPU

15.95 MC6820 Periph, Interface Adapter

6.95 MC6810AP1 128 x 8 Static RAM

9.95 MC6830L8 1024x8 Bit ROM

System Controller Bus Driver 10.95 Z80

CPU

2513(2140)2513(3021!2518

MM5230

CPU'SSuper 800B8 BIT MPUCPU

SB'S1024 OynamicHex 32 BITHex 40 BITDual 132 Bit SSR512 Dynamic1024 DynamicDual 256 BITDual 512 BITQuad 80 BIT102-1 StaticFilfl16 . 4 Reg

UART'S30K Baud

RDM'SChar Gen -upper caseChar Gen -lower caseChar Gen.2046 BIT (512x4 on 256x8)

RAM'S

$19.9524.9515.006.00

15.0029.95

2.256 95

_2_2i

1702A

5203

82S23

B2S123

74S28?

20J8204832 x 8

S 9.959.951095

|27SB~

2716

6301-1

6330-1

Ed mmTn-State Bioolar

Open Condor B

SPECIAL REQUESTED ITEMS

FCM3817AY-3-8500-1AY-5-9100AY-5-9200AY-5-9500AY-5-23766374S2S115

11C90

4N33

BT20

8T97

HD0165

MCM6571

MCM6574

7205

ICM7045ICM7207ICM7208ICW7209MK5O240DSO026CH

25.00 MCM6575 13 50 TIL30B

ITEMS

CLOCK CHIPSMM5309 S9.95

19.95 9368

3.95

MM5311

4.95

24.95 LD110/111

25.00/sel

MM5312

7.50 95H90

11.95

MM5314

22.00 MC3061P

3.50

MM5316

6.95

7.50 MQ4pt6 (74416) 7.50

MM531B

9.95

17.50 MCMU8L7

8.95

MM5369

2.95

3 75 MC1408LB

9.95

MU5B41

9.95

10 50 74C922

995

CT7001

5.95

PARATRONICS

Featured on February's Front Cover of Popular Electronics

Logic Analyzer Kit mociamdoa mo^ho

Model 100A -,,,,,

$229.00/kit

in ■mi tm

• Analyzes any type ol digital system

• Checks data rates in excess ot 8

million words per second

• Trouble shoot TTL. CMOS. DTL, RTL,Schottky and MOS families

• Displays 16 logic states up to 8 digits wide

• See ones and zeros displayed on yourCRT, octal or hexadecimal format

• Tests circuits under actual operating conditions

• Easy to assemble — comes with step-by-step constructionmanual which includes 80 pages on logic analyzer operation.(Model 100A Manual -$4.95)

Some applications are:Troubleshooting microprocessoraddress, instruction, and data flowExamine contents of ROMSTracing operation of control logicChecking counter and shiftregister operationMonitoring i/0 sequencesVerifying proper system operationsduring testing

PARATRONICS TRIGGER EXPANDER - Model 10

Adds 16 additional bits. Provides digital delay and qualification of Input cand 24-bit trigger word. — Connects direct to Model 100A tor integrated ui

Model 10 Kit - $229.00

Baseplate — S9.95Modal IB Manual — MJfl

RnZT&'Wl

Comes with testleads, operating manualand spare luse

3V2-DIQI1 Portable DMM

• Overload Protected

• ,3" hiph LED Display

• Gallery or AC operation

• Auto Zeroing

• irnv. IVa, 0 1 otim resolution

• Overange reading

• 10 meg input impendence

• DC Accuracy 1% typicalRanges: DC Vollage 10-1000V/AC Vollage: O-1O00V

Fret) Response1 50-400 HZDC/AC Current: 0-lOOmAtlesistnnce; 0-I0 megohmSize: 6.4" x 4.4" x T

Accessories:AC Adapter BC-2B $9.00Rechargeable

Batteries BP-26 20.00Carrying Case LC-2B 7.50

CONTINENTAL SPECIALTIES

PR0T0 BOARD 6 Other cs Prnin Boards

100 MHz 8-Digit Counter

• 20 Hz-100 MH: Range . Four power souces, I.e.

• .6' LED Display batteries, 110 or 220V with

• Crystal-controlled timebase charger 12V with auto

• Fully Automatic lighter adapter and external■ Portable — completely 7.2-10V power supply

.SS^Sr.r* m*'m $134.95

X5.63"

ACCESSORIES FOR MAX 100:Mobile Charger Eliminator

use power from car ballon/ Model 1DD — CLA 13.95

Charger/Eliminator

use 110 V AC Model 100 — CAI 19.95

$15.95

(6" long X 4" wide)

PB100 - 4.5" x 6" $ 19.95

PB101 - 5.8" x 4.5" 29.95

PB102 -7"x4.5" 39.95

PB103-9" x6" 59.95

PB104 -9.5" It 8" 79.95PB203 • 9.75 x 6VS x 2* 80.00

PB203A - 9.75 x 6'A x 2¥< 129.95liorlodes powej sjpply)

LOGIC MONITOR

for DTL. HTL. TTL or CMOS Devices

$84.95

11 PIN16 PIN24 PIN40 PIN

$4.504.758.50

13.75

DESIGN MATES

DM1 - Circuit Designer

$69.95DM2 ■ Function Generator

$74.95DM3 - RC Bridge

$74.95

QT PROTO STRIPS

••MUM.'"-'

IB*

in typo0T-59SQT-59DQT-47SOT-47BQT-35SQT-35BQT-18SGT-125QT-8SOI-7S

2 50

2.004 753 753.25

Experimenter 300 $ 9,95Experimental- 600 510.95

$5.00 Minimum Order — U.S. Fundi OnlyCallloinlo Reildenti — Add 6% Salfli Tax

Spec Sheets - 25c — Send 35c Stamp lor 1978 CatalogDaaltr Information Available

1978CATALOG

NOWAVAILABLE

1021-A HOWARD AVE., SAN CARLOS, CA. 94070PHONE ORDERS WELCOME — (41?) 592-8097

Advertised Prices Good Thru March

The IncrediblePennywhistle 103'

$129.95 Kit Only

The Pennywhistle 103 Is capable ol recording data to and from audio tape withoutcritical speed requirements lor the recorder and it is able to communicate directlywith another modem and terminal for telephone "hamming" and communicationslar the deaf. In addition, it is tree ol critical adjustments and is built with non -precision,readily available parts.Data Transmission Method Frequency-Shift Keying, full-duplex (half-duplex

selectable).

Maximum Data Hale 300 Baud.

Data Formal Asynchronous Serial (return to mark level required

between each character),Receive Channel Frequencies .. .2025 Hz for space; 2225 Hz for mart;.Transmil Channel Frequencies ..Switch selectable; Low (normal] = 1070 apace

1270 mark; High = 025 Space. 2225 mart;.

Receive Sensitivity -46 dbm accoustically coupled.

Transmit Level -15 dbm nominal. Adjustable from -6 dbm

to -2Qdbm.Receive Frequency Tolerance ...Frequency reference automatically adjusts lo

allow for operation between 1800 Hi and 2400 HzDigital Oala Interlace EIA RS-232C or 20 mA current loop (receiver is

optoisolaled and non-polar)

Power Requirements 120 VAC, single phase. 10 Watts

Physical Ail components mount on a single 5" by 9"

ptinted circuit board. All components included.Requires a VOM. Audio Oscillator, Frequency Counter and/or Oscilloscope to align

NEW! BULB-ENERGY SAVER

BES-1

'I »

Bulb lasts 3 ormore limes longer.Fits Standard Socket6 watts to 200 watts1-9 10 +$1.50 ea. 1.25 ea

BULB-ENERGY SAVERS used lor years bymajor industrial users — now available lorhome or office use. Bulb Savers can cutelectrical bills by as much as 3%.BULB-SAVERS lengthens light life by:

1. Acting as an electrical "shock ab-sorber", turns (he bulb on slowly, eliminat-ing the "thermal shock". Bulb life increases300 percent.

2. Banishes Current "Surges". Cushionsline voltage surges when other loads cutpower line.

3. Reduces Energy Consumption

DIGITAL STOPWATCH

• Bright G Digit LED Display

• Times lo 59 minutes 59 59 seconds■ Crystal Controlled Time Base

• Three Stopwatches in One

Times Single Event — Split S Taylor

• Size4.5-x2.15-x.90" |4i'»ounces!

• Uses 3 Penlne Cells

Kit — $39.95

Assembled — $49.95

Heavy Duty Carry Case $5.95

Stop Watch Chip Only (7205) S19.95

3V2DIGIT DPM KIT

s&

• New Bipolar Unit • Auto Polarity

• Auto Zeroing • Low Power

. .5" LED . Single IC Unit

Model KB500 DPM Kit $49.00

Model 311D-5C-5V Power Kit $17.50

JE700 CLOCK

The JE700 15 3 low cost digital clock. Putis a very high quality unii The unit lea-luies 3 simulated walnut case with di-mensions ol 6 i?'? 1 1 It unices aMAr\t72 higti bugritness readout and theMM5314 clock chip

KIT ONLY $16.95

HEXADECIMALENCODER 19-KEY PAD

.1-0. ABCDEF

• Shift Key

• 2 Optional Keys

$10.95 each

New 63 KEY KEYBOARD $29.95

This Keyboard features 63 unencoded SPST keys unattached toany kind ol P C B A very solidmolded plastic 13' > 4

HO01B5 Encoder Chip (encodes 16 Keys)

AY-5-2376 Encoder Clito (encodes 88 Kevst

JE803 PROBE

The Logic Prone >s a unit whicn is lot trie mosl panmrtespensiDie in irouDie shooting logic familiesTTL DTL RTL CMOS tl derives the power itneeds 10 operaie directly ott ot tne orcuilest drawing a scam to mA mai 11 uses a MAN3readout 10 mdicaie any ol the loiiowmg states byIhese symbols 1H1 1 1LOW1 - 0 1PULSE1 P TheProbe cm delect niqri IreQuency Dulses to J5 Mwit can 1 Be useo al MOS levels c circuit damagewill result

$9.95 Per Kit

printed circuit board

PL 5V 1A Supply

This is a Standard TTL power supply using ihe welt knownLM309K regulalor IC to provide a solid 1 AMP ot current at 5votls We try to make things easy for you by providingeverything you need m one package including the hardware

..,.», $9.95 Per Kit ^>

212

BYTE March 1978

SN7-100N

SN7401NSN7402KSN7403NSN7404NSN7405NSN7406NSN7407NSN740BNSN7409NSN7410NSN7411NSN7412NSN7413NSN7414NSN7416NSN74I7N5N742QNSN7421NSN7422NSN7423NSN7425NSN7426NSN7427NSN7429NSN743QN5N7432NSN7437NSN743BNSN7439NSN7440NSN7441NSN7442NSN7443NSN7444NSN7445NSN744BNSN7447NSN7448NSN74S0NSN7451NSN74S3N5N7454NSN7459ASN74E0NSN7470N

CO4000CD4001CD40O2CD4006CD4007C04009C04010CD40UCD4012CD40I3C04014CD40tSCD4016CD4017C0401BCD4019CD4020CD4021CD4022CD4023CD4024CD4025C04Q26CD4027CD4028CU4029CO4030CD4035C04040CD4041C04042

7400N TTL

*fBW?

SN7472N

.39

SN7473N

.39

SN7474N

.35

SN7475N'

.50

SN7476N

.35

SN7479N

5.00

SN7460N

.50

SN7482N

.99

SN74B3N

70

SN7485N

.69

5N74B6N

.39

SN7488N

3.50

SN7489N

2.49

SN7490N

.45

SN7491N

.75

SN7492N

49

SN7493N

.49

SN7494N

79

SN7495N

79

SN7496N

.79

SN7497N

3.00

SN74I0CN

1.25

SN74107N

.39

SN74109N

.95

5N74116N

1.95

SN74121N

.39

SN74122N

39

SN74123N

.50

SN74125N

60

SN74126N

.60

SN74I32N

1 75

SN74I36N

95

SN74141N

1 15

SN74142N

2.9S

SN74143N

3.25

5N74144N

3.00

SN74I45N

1.15

SN74147N

2.35

SN74I4BN

2 Of)

SN74I50N

SN74151N

79

SN74153N

.89

SN74154N

1.25

SN74155N

.89

SW74156N

.89

SN74157N

.89

SN74160NSN74161NSN74162NSN74163NSN74164NSN74165NSN741B6N5N74I67NSN74170NSN74172NSN74173NSN74174NSN74175NSN74176NSN74I77NSN74179MSN741BONSN741B1NSN74182NSN74184NSN74185NSN74186NSN74187NSN74I88NSN74190NSN74191NSN74192NSN74193NSN74194NSN74195NSN74196NSN74197NSN74198NSN74199NSN74200NSN74251NSN74279NSN74283NSN742B4NSN74285NSN74365NSN74366NSN74367NSN74368NSN7439QNSN74393N

20% Discount lor 100 Combined 7400's

CMOS

CO4044

CD4046

CD4047

CD4046

CD4049

CD4050

CD4051

C04053

CD4D56

CO40S9

CD4QB0

CD40G5

CO4068

CD4069

CD4070

CD4071

CD4072

CD4076

CD40B1

CD4082

CD4098

MCI 4409

MCI4410

MC14411

MC14419

MC14506

MC14507

C0450B

CD4510

CD4511

CD4515

CD451B

CD-I 520

1.29

MC14562

14.50

CD4S6B

2.25

MC14583

350

74CD0 Series

74C00

.39

74C02

.55

74C04

.75

74C10

.65

74C14

3 00

74C20

.65

74C30

.65

74C42

2.15

74C73

1 50

74C74

1.15

74C69

4,00

74C90

3.00

74C93

2.00

74C95

200

74C107

1.25

74C151

2.90

74C154

3.00

74C157

2.15

74C160

3.25

74C161

3.25

74C163

3.00

74C164

3.25

74C173

2.60

74C193

2.75

74C195

2.75

80C95

1.50

BOC97

1.50

lM3UOH

IM301HLM301CNLM302.H

LM304K

LM3Q5H

LM3Q7CN

LM308H

LM30BCN

LM309H

LM309K

LM310CN

LM31IH

LM311N

LM317K

LM318CN

LM319N

LM320K-5

LM320KS 2

LM32QK12

LM320K-15

LM320T5

LM320T.5 2

LM320T8

LM320M2

LM320T15

LM320M8

LM320T24

LM323K-5

LM324N

IM339N

LM340K-5

LM340K-6

LM340K-8

LM340K12

LM340K-15

LM340K-1B

LM340K-24

LM340T-5

LM340T-6

LINEAR

LM340T-8 I 25

LM340M2 125

LM340I-15 1.25

LM340T-16 1 25

LM340T-24 1.25

LM350N 1 00

LM351CN .65

78MG 1.75

LM370N

LM373N

LM377N

LM380N

LM3B0CN

LM3B1N

LM382N

NE501K

NE510A

NE529A

NE53IH

NE536T

NE540L

NE550N

NE5S5V

NE560B

NE561B

NE562B

NE56SH

NE565N

NE566CN

NES67H

NE567V

LM703CN

LM709H

LM709N

LM7I0N

LM711S

LM723H

LM723N

LM733N

3,25

6 004.953.00

LM739N

LM741CH

LM741CN

LM741-14N

LM747H

LM747N

LM748H

LM74BN

LM1303N

LM1304N

LM1305N

LM1307N

LM1310N

LM1351N

LM1414N

LM1458CN

LM1496N

LM1556V

LM2111N

LM2901N

LM3053

LM3065N .69

LM39O0N(340t)49

LU3905N 89

LM3909 1.25

LM5556N

MC555BV

LM7525N

LM7534N

2.95

2.95

LM7545075451CN75452CN7S453CN75454CN75491CN75492CN75494CNHC4194RC4195

4.95.49

74LS0074LS0274LS0374LS0474LSC574LS0874LS1074LS1374LS1474LS2074LS2674LS2774LS2874LS3074LS3274LS4074LS4274LS4774LS51741S5574LS7374LS74

» 74LS00 TTL

74LS7674LSB374LS8574LS8674159074LS9274LS9374LS9574LS9674LS10774LS10974LS11274LSI2374LS13274LS13674LS13874LSI3974LS151

74LSI 5574LSI5774LS16074L516174LS16274LS16374LS16474LS17574LS18174LS19074LS19174LS19274LS19374LS19474LS19574LS2S374LS25774LS26074LS27974LS36774LS36874LS670

BUGBOOK

Continuing Education Series

BUQBOONS I and II S17.00pingt

Hi Plltt R. HBh». ElDid 0. Lnun, W4HYJ

Sou u i wt Itwsc Iwo EkkMiI outline Q>er 90 etpenrTXfits etsign*d Id rtictilht rudir ill IM «ill rwtd to know JOout TTL Iodic chips to it* llwm Iflurctnn wttn miciop(oC(iMr lyiltms You 1 Inm iBout fflt tajie analing pitai. Hip-Hops, ijiches. buses, lecodsisUOflijpUrn. RAM's. ROWs. ma rnucn. much r

BUGBOOK III

1, DM! 0. u

VI I'M mouM you

llbiHoul U»H1 Chip — But i. and your microcomputer. IIRS 23?C InMrlue snnnarrj Parliculirly re

THE 555 TIMER APPUCATIOKSSOURCEBOOK WITH EXPERIMENTS

S6.95 BUGBOOK 111

kf Pilor R H«n(, Ottll 0. LirtM, 1

WS4HYJ. Jotnlh.n A. Tirollit* rs ih> book Hut puts II ill toggthar Besides having mich viiuithere ira i sartas o( aiptnmenls In which the reader complerely enolBOO chip pin by pin and mtiDduas you la tha Mark 80 mcrocomunque easily interfaced system II is recommended thai you hire irgrcund on the BUGBO0K5 I t It berate proceeding with BUG3O0K III

INSTRUCTOR'S MANUAL

NeceSMry lor instruction nl Bjgoook I mil II Answerseiperinienlj. suggestiontlorluilherieaaing. philosophy otWQW (ii'ciioiinn * must lor set-leaching indiyiduats

OP AMP MANUAL

ampMiers Over 2S ei

Rony, Janittian A. Tinalies. DOBOA microcompuier proflramimg An integrated approach Is Mtf-id B08OA inteljcing.'protol Bugbook V Into i ire;Interlacing Detail & i.

CM08-M - DESIGNERS PRIMERAND HANDBOOK

Stan il disk: '.liuduic gl CMOS aewces ihruugti mlegulion ml

COMPLETE MANUAL FOR DIGITAL CLOCKS by John Weiss and John Brooks

Familiarizes technician or hobbyist will) basic theories behind digital clocks Includes (rouble shooting guides, basiccharacteristics ol clocks, soldeting techniques dock component daia sheets and construction lips. $3.95

XC209XC209XC209XC209

GreenDrang*Yellow200' dn

DISCRETE LEDS

XC111

xcm

XC111

XC22

Red

XC22

Green

XC22

Yellow

XC22

Orange

SSL-22

RT

XC526XC526XC526XC526XC526

XC556XC556XC556XC556XC556XC556

.190" dia.Hed 10«t

Green 4<51

Yellow 4'S1

Orangt 4,'S5

.015" dla.MV50 - Red - 6.S1

GreenYellowOrange

INFRA-RED LED

SALE

DISPLAY LEDS

SALE

TYPE

MAN 1MAN 2MAN 3MAN 4MAN 52MAN 71MAN 72MAN 74MAN 81MAN 82MAN 64MAN 3620MAN 3630MAN 3640MAN 4610MAN 4640MAN 4710MAN 4730MAN 4740MAN 4810MAN 6610MAN 6630MAN 6640MAN 6650MAN 6660

POLARITY I

Common Anode-ted5 x 7 Dot Matrix-redCommon Cathode-redCommon Cathode-redCommon Anode-greenCommon Anode-redCommon Anode-redCommon Cathode-redCommon Anode-yellowCommon Anode-ye HowCommon Catnodt-yellowCommon Anode-orangeCommon Anode-orange -1Common Calhode -orangeCommon Anode-orangeCommon Cathode-orangeCommon Anode-red ilCommon Anode-redCommon Cathode-redCommon Anode-yellowCommon Anode-orange-D.D .Common Anode-orangeCommon Cathode -orange -D.DCommon Cathode-orange i1Common Anode-orange

TYPE

MAN 6680

MAN 6710

MAN 6730

MAN 6740

MAN 6750

MAN 6760

MAN 6780

DL701

01702

DL704

DL707

DL741

DL746

DL747

DL749

OL750

DL33B

FND70

FND503

FND507

POLARITY

Common Cathode-orangeCommon Anode-red-D.D.Common Anode-red 11Common Cathode-red-O.D.Common Caihode-red 1.1Common An ode-redCommon Cathode-redCommon Anode-red rlCommon Calhode-redCommon Cathode-redCommon Anode-redCommon Anode-redCommon Anode-red -1Common Anode-redCommon Cathode-red ^ 1Common Cathode-redCommon Cathode-redCommon Cathode (FND359)Common Calhode (FND500)Common Anode (FND510)4 x 7 Srjl Dlgll-RHOP4 K 7 Sgt. Diglt-LHDPOvenange character (*1)4x7 Sgl. Dlrjll-Hexadecimal

RCA LINEAR

CA30I3CA3023CA3035CA3039CA3046CAM S3CA3059CA3060CA3080CA3081

IS CA3082

5G CA3083

48 CA3086

35 CA3089

30 CA3091

50 CA3I02

25 CA3123

25 CA3130

85 CA3140

00 CA340ICA36O0

3502952 15

XR-2206KB Kit S19.95

WAVEFORMGENERATORS

XR-205 S8 4C

XR-2206CP 5.50

XR-2207CP 3 85

XF1-2206KA Kit $14.95

EXAR

MISCELUNEOUS

STEREO DECODERSXR-1310CP S3 20

XR-1310EP 3 20

XR-IBOOP 3 2C

XR-2567 2 99

TIMERS

XR-555CP S .49

XR-320P I 55

XR-556CP 1 B5

XR-2556CP 3 20

XR-224QCP 4.80

PHASE LOCKED LOOPS

XR-210 5 20

XR-215 6 60

XR-567CP 1 95

XR-567CT 1 70

13 pin22 pin

14 pin

16 BinIB pin?4pin

IC SOLDERTAIL — LOW PROFILE (TIN).SOCKETS

24 pin2Bpin36 pin

35 SOLDERTAIL STANDARD (TIN)

26 pin

SOLDERTAIL STANDARD (GOLD)

36 pin

WIRE WRAP SOCKETS (GOLD) LEVEL #3

22 pin24 pin26 pm

36 pin40 pin

27 OHM 33 OHM68 OHM 82 OHM

50 PCS. RESISTOR ASSORTMENTS $1.75 PER ASST.

10 OHM 12 OHM 15 OHM 18 OHM 22 OHMASST. 1

ASST. 2

ASST. 3

ASST. 4

ASST. 5

ASST. 6

ASST. 7

ASST. 8R Includes Resistor Assortments 1-7 (350 PCS.) $9.95 ea.

39 OHM

47 OHM

56 OHM

1/4 WATT 5%

50 PCS.

100 OHM

120 OHM

150 OHM

270 OHM

330 OHM

390 OHM

1/4 WATT 5%

50 PCS

660 OHM

820 OHM

IK

1 8K

2 2K

2 7K

1/4 WATT 6%

50 PCS

4 7K

5 6K

D6K

12K

15K

18K

1/4 WATT 5%

50 PCS

13K

39K

47K

B2K

'OQK

1208

1/4 WATT 5%

50 PCS

220K

270K

330K

560K

680K

B20K

1/4 WATT 5^.

50 PCS

1 5M

IBM

2 2M

3 9M

4 7M

5 6M

1/4 WATT 5%

50 PCS.

$5.00 Minimum Order — U.S. Fundi OnlyCalifornia Rsildenti — Add 6% Silet Tax

Spec Sheets - 25c — Send 35e Stamp lor 1978 CatalogDaaler Information Available

1021-A HOWARD AVE., SAN CARLOS. CA. 94070

PHONE ORDERS WELCOME — (415) 592-8097

Advertised Prices Good Thru March

WIRE-WRAP KIT — WK-2-W

WRAP . STRIP . UNWRAP :*n

• Tool tot 30 AWG Wire ^K. Roll ol 50 Ft. White or Blue 30 AWG Wire ■

• 50 pes. each 1". 2". 3" & 4" lengths —pre-stripped wire.

$11.95

WIRE WRAP TOOL WSU-30WRAP . STRIP . UNWRAP-S5.95

WIRE WRAP WIRE — 30 AWG

25tt.min.S1.25 50tt.$1.95 100fl.S2.95 1000ft. $15.00SPECIFY COLOR — White - Yellow - Red - Green • Blue • Black

WIRE DISPENSER — WD-30

• 50 ft. roll 30 AWG KYNAR wire wrap wire $3.45 i

• Cuts wire to desired length

• Strips 1" of insulation Specify

- Blue-Yellow-White-Rer

REPLACEMENT DISPENSER SPOOLS FOR WD 30

Specify blue, yellow, white or red Sl.tt/tpool

,„,ePntr»Kanc. STEWART WARNER sE£ral

i'.rl Hitimil I

SW7401 si.aoflot

SW7407 2.20

SW7416 2.20

SW7417 2.20

SW7420 1.30

SW7423 2.20

SW7425 1 70

SW7427 1.50

SW7430 1.50

SW7432 1.50

SW7437 150

SW7438 1.50

SW7440 1.20

SW7443 3.50

SW7444 3.50

SW7445 3.50

SW7446 4.00

SW7450 1.20

SW7453 t.20

SW7454 120

SW7460 1.20

SW7472 2.20

SW7475 3.50

SW7480 2 90

Pre-tubed

1000 P/N 10tmln.|: S80.00/V)tSW7482 S4 90W

160.00 SW7483 3.50

SW7486 2.20

SW7491 3.50

SW7494 3.50

SW7495 3 50

SW7496 3.50

SW74100 6.90

SW74104 2.20

SW741D5 2.20

SW74107 2.20

SW74121 2.20

SW74123 2.50

SW74145 5.50

300.00 SW74150 6.90

SW74151 3.50

SW74153 4.00

SW74156 4.00

SW74180 4.50

SW74181 9.90

SW741B2 4.50

SW9601 2.50

300.00 SW9602 4 90

180.00180.00100.0018000130.00110.00110.00110.00110.00110.00BOM

350.0080.0080.0080.0080.00

31.0036.0036.0041.00

180.00300.00300.00300.00300 00650.00180.00180 00180.00

■ No

250.00

mixing or combining prices

TV GAME CHIP SET — $9.95

Includes AY-3-8500-1 Chip and 2.010 mhz crystal(2.010 crystal — S.99 ea/AY-3-8500-1 Chip—$9.95 ea.)

nee

1N7461N751A1N7521N7531N7541N9591N965B1N5232IN52341N5235IN52361N4561N4561N485A1N40011N4002IN J 003IN4004

ZENERS -

VOLTS W

3.3 400m

5.1 400m5.6 400m

6.2 400m6.8 400m8.2 400m15 400m5.6 500m6.2 500m6.8 500m7.5 500m

50 PIV 1 AMP

100 PIV 1 AMP

200 PIV 1 AMP

400 PIV 1 AMP

DIODES -

PRICE TYPE

4/1.00 1N4005

4/1.00 1N4006

4/1.00 1N4007

4/1,00 1N3500

4/1.00 1N4148

8/1.00 1N4154

4/1.00 1N4305

" 28 1N4734

28 1N4735

2B 1N4736

28 1N4738

6/1.00 1N4742

6/1.00 1N4744

6/1.00 1N11B3

12/1.00 1N11B4

12/1.00 1N1185

12't.00 1N11B6

12/1.00 1N1188

RECTIFIERS

VOLTS W

600 PIV 1 AMP800 PIV 1 AMP1000 PIV 1 AMP200m

10m10m

15/1.0012/1.0020/1.00

1w

12

15 tW

50 PIV 35 AMP

100 PIV 35 AMP

ISO PIV 35 AMP

200 PIV 35 AMP

400 PIV 35 AMP

SCR AND FW BRIDGE RECTIFIERS

C36DC38M2N2328MDA 960-1MDA 980-3

ISA @ 400V3SA @ 200V

1.6A@200V12A@50V12A @ 200V

MPSWS S/fl DO

MPS AM S/tl 00

iNtlt 4/1100

2N2:iM 3/tl.OO

?u:?:>\ 4(it in

ZN22Z2A S:-(1 on2N236S Srjl 002N2M9A 4/S1 DO2t474B4 4/JI002N2WSA 4.iiL«i2N2907A2N2*2i2N30J5JWDS5MJE2KS«JE30M2KU02

TRANSISTORS

'

2H36M2N3T022N3704?H3T052N3/062«70(-

b/Jl 005/11.DO541005/11.00S/fl.00SSI tw

5,11002/1100

II 005/IV005,1100

PH3569 4d1 00

mm si.oo

IN3772 K.25

2N3W3 5(11.00

2N3906 41100

2N4013 3.1100

2H4014 3H1 X

2N4123 64100

rami 4.11.00

v

2N4401 4(1100

2N4402 4(11 00

2N4403 44V 00

2K44M 541 00

2N50S6 441 00

2N50S7 441 00

2N50U 411 00

2N5099 441 00

2N5129 54100

2N5134 541 00

2N513S S4t 00

2N5?09 54! 00

2NS210 5,11 00

2N5432 U.0C

2NM49 311 DC

2N595I 541 OtCI068TSCR 241 Ot

40409 SI 7!

CAPACITOR

50 VOLT CERAMIC

10 pt22 pt47 pf100 pf

220 pi470 pt

001ml00220047ml01ml

-1/35V.15/35V.22/35V.33/35V47/35V.68/35VI 0/35V

CORNER

1-9 10-49 50-100

05 .04 .03 OOt/iF

.05 .04 .03 0047iiF .05 .04

.05 .04 .03 .OVF .05 .04

.05 .04 .03 022/iF .06 .05

.05 .04 .03 .047MF 06 .05

05 .04 .035 .VF .12 09

100 VOLT MYLAR FILM CAPACITORS

.12 10 .07 .022ml .13 .11

.12 .10 .07 ,047mt .21 ,17

12 .10 .07 .1ml 27 23

.12 .10 .07 ,22mt .33 .27+20% DIPPED TANTALUMS (SOLID) CAPACITORS

.28 .23 .17 1.5/35V .30 .26

.28 .23 .17 2.2/25V .31 .27

.28 .23 .17 3.3/25V .31 .27

.28 .23 .17 4.7/25V .32 26

.28 .23 .17 6.8/25V .36 .31

,2B .23 .17 10/25V .40 .35

.28 .23 .17 15/25V .63 .50MINIATURE ALUMINUM ELECTROLYTIC CAPACITORS

Radial Lead

1.0/50V3.3/50V4.7/25V10/25V10/50V22/25V22/50V47/25V47/50V100/25V100/50V220/25V220/50V470/25V '1000/16V2200/16V

.13

.10

.47/25V.47/50V1.0/16V1.0/25V1.0/50V4.7/16V4.7/25V4.7/50V10/16V10/25V10/50V47/50V100/16V100/25V100/SOV220/16V470/25V

Circle 60 on inquiry card.

BYTE March 1978

213

What's New?

Highlights from Creative Computing

PUBLICATIONS

New Catalog of Circuit Design Aids

>,, t^i *

Learn BASIC with ThisSelf Instruction Course

The 24 page Complete Bugworkscatalog describes more than 155 circuitdesign and educational products. Thecontents include solderless sockets,breadboards and accessories, plug infunctional modules called "outboards,"designer "breadboxes" which includepower supplies, controls and displays,and the MMD-1 Mini-Micro Designermicrocomputer development system.The hardware is supported by a set of 16texts including the popular Bugbookseries of combined texts and labmanuals. The catalog is available fromE & L Instruments Inc, 61 First St,Derby CT 06418, (203) 735-8774."

Circle 616 on inquiry card.

Game Playing with BASIC

This book includes over 60 computergames and puzzles such as three-dimen-sional Tic Tac Toe, Nim, Roulette,Go-Moku, and many others. The authordescribes the rules of each game andincludes illustrative flowcharts and dia-grams. The last chapter contains 26games and puzzles for reader solution.Game Playing with BASIC, written byDonald D Spencer, is available paper-bound for $6.95 from Hayden BookCompany Inc, 50 Essex St, RochellePark NJ 07662, (201) 843-0550."

Care and Feeding of Floppy Disks

This free brochure offers suggestionsfor the safe handling and storage offloppy disks. The publisher manu-facturers a storage cabinet and indexingsystem for keeping track of a libraryof floppies, priced at $59.95 for alimited time. The brochure is availablefrom Advance Access Group Inc, 10526W Cermak, Westchester IL 60153, (312)562-5210."

Circle 61 8 on inquiry card.

The EC-1100 course combines pro-grammed instruction text with practicaldemonstration programs and practiceproblems to teach BASIC languageformats, commands, statements andprocedures. The course goes beyondconventional BASIC texts to give thestudent an introduction to the creativeand problem solving aspects of pro-gramming in BASIC. The EC-1100course is keyed to the Heath computersystems, but it could be a useful supple-ment for other computers using BASIC.The course is priced at $29.95 and isfurther described in a free catalogavailable from Heath Company, Dept350-450, Benton Harbor Ml 49022."

Circle 621 on inquiry card.

Computer Store SurveyRates Manufacturers

An opinion survey of the nation'scomputer stores rates the top 37 per-sonal computer manufacturers on 17performance parameters such as delivery,packaging, warranty, pricing and relia-bility. Prepared from questionnairesand telephone interviews covering 450stores, the survey also deals with busi-ness problems, trends, and marketcharacteristics as seen by store managers.For more information including prices,contact Image Resource, 717 LakefieldRd, Suite B, Westlake Village CA 91 361,(805) 495-6277."

Circle 622 on inquiry card.

How to Fix Your OwnCassette Recorder

The Workbench Guide to Tape Re-corder Servicing shows you how to fixproblems with portable cassette re-corders, open reel tape decks and 8 trackcartridge players. It covers topics suchas how to disassemble any machine inshort order, how to make sense out ofmanufacturers' specifications sheets, andhow to pinpoint problems in tape trans-port mechanisms. Written by G HowardPoteet, the book is $10.95 from ParkerPublishing Company Inc, West NyackNY 10994."

Circle 623 on inquiry card.

This book contains a collection ofarticles, fiction, foolishness, puzzles,programs, computer games and reviewsfrom the Volume 2 (1976) issues ofCreative Computing magazine. Duringthis period, home computers just begancoming on the scene. This volumereflects the transition from minis andtimesharing terminals to the new micro-systems, although the diversity of thecontents guarantees there will be some-thing for just about everyone.

15 new computer games aredescribed with complete listings andsample runs for each; 67 pages aredevoted to puzzles, problems, programs,and things to do with your computer orterminal. Frederik Pohl drops in for avisit along with ten other imaginativestorytellers. The staggering diversity ofthis book makes it an ideal point fromwhich to jump into the amazing worldof recreational or educational comput-ing.

7776 Best of Creative Computing —Volume 2 is available for $9.95 post-paid from Creative Computing, Attn:Pamela, POB 789-M, Morristown NJ07960."

Circle 619 on inquiry card.

Book of MUMPS

This new book describes applica-tions of MUMPS, the MassachusettsGeneral Hospital Utility Multiprogram-ming System. MUMPS is a powerfulinterpretive language featuring text edit-ing and searching capabilities, a hier-archical file system, and a shared database with multiple users, which hasbeen used for many medical applica-tions. The 48 page Book of MUMPSlists 230 MUMPS application programsand 197 institutions which are usingMUMPS. Information is also includedon the MUMPS Users' Group (MUG)and its application library, MUMPSvendors and other MUMPS publications.The book is $2 from the MUMPS Users'Group, 700 S Euclid Av, St Louis MO63110, (314) 454-3364."

Circle 620 on inquiry card.

214

BYTE March 197S

TOUCH TONE ENCODER KIT

Simplicity itself to complete. No other parts required, nocrystal required. The back of the touch pad has etched &drilled PC board and you solder the encoder chip to it. Addyour own small speaker & 9 volt battery and you are done.A touch of the pad produces the proper tone signal fromthe speaker. We furnish schematic and instructions.

SP-149-B $12.95

WIRE WRAP WIRE

TEFZEL blue #30 Reg. price$13.28/100 ft. Our price 100 ft $2.00;500 ft $7.50.

MULTI COLORED SPECTRA WIRE

Footage 10' 50' 100'

8 Cond.

#24 $2.50 9.00 15.00

12 "

22 3.00 11.00 18.00

14 "

22 3.50 13.00 21.00

24 "

24 5.00 20.00 30.00

29 "

22 7.50 28.00 45.00

Great savin

gs as these are about 1 /4

book prices

All fresh & new.

TOUCHTONE ENCODER CHIP

Compatible with Bell system, no cry-stal required. Ideal for repeaters &w/specs. $6,00

LAMBDA POWER SUPPLIES

LM-D-12-OVP 12 volts DC 10 ampS60, LV-EE 5-OVP 5 VDC 74 AmpS75.00

VIATRON CASSETTEDECKS

The computer cassette deck alone$35. Set of Control boards forabove $40.

A

ft^JLi <

VIDEO DISPLAY from Viatron systems. Acceptscomposite video signals. 9 inch transistorizedCCTV black & white CRT monitor. Ready to go,checked out. 115 volt AC 60 cycle. With circuitdiagram.

$75.00

FAST CHARGE AA NICADS $1.25 each

ws«m

IR NIGHT VIEWER $199.00

Custom made, complete with light source & viewer in onepiece. Comes with carrying strap. Ready to operate with 6volt lantern battery. Guaranteed by the manufacturer. See intotal darkness. Great for scientists, viewing nocturnal animals& birds, criminal investigation . . . observe without being ob-served, and a ball for just plain snooping!!!! Sorry to say butno shipments to Calif, (lens may vary slightly from pic)

SPL-21 $199.00

^/ffesh^ia.

Please add shipping cost on above. Minimum order $10

FREE CATALOG NOW READY # SP-10P.O. Box 62, E. Lynn, Massachusetts 01904

Circle 66 on inquiry card.

BYTE March 1978

215

What's New?

Microprocessor Course on TV

An instructional course in micro-processors for industry, designed aroundthe Micro-68 training computer, is nowavailable in the form of 30 half hourcolor video cassette sessions. The coursewas developed by Electronic ProductAssociates Inc in conjunction withColorado State University. Course mate-rials include the textbook UnderstandingMicroprocessors, the 6800 ProgrammingManual and System Design ReferenceManual, the Micro-68 Lab Manual andMicro-68 User's Manual, and a coursestudy guide. The cassette package maybe purchased for $7060 including oneMicro-68 computer trainer and one setof documentation, or it may be leasedfor as little as $875 and $140 for thecomputer trainer. Additional computertrainers are available at the discountedprice of $533. A 30 minute preview tapemay be rented for a week for $50. Thecourse is available from the universityor from Electronic Product AssociatesInc, 1157 Vega St, San Diego CA 92110,(714) 276-8911.■

Circle 593 on inquiry card.

Gang Write Your EROMs With This Programmer

The Model 16 gang programmer iscapable of programming nearly one

million bytes of erasable read onlymemory per hour. The unit simul-taneously programs 16 EROMs; includesa built in calibration mode; providesROM continuity tests which detectfaults in memory, socket connections,and' programmer electronics; automati-cally pretests the programmer voltages;and computes checksums to ensurethe integrity of the programmed in-formation. RS232C serial 10 at select-able data rates is included, and aninteractive alphanumeric display simpli-fies operation. The Model 16 measures8 by 1 3 by 23 inches (20.32 by 33.02 by58.42 cm), weighs 38 pounds and costs$4800 from Data I/O Corp, POB 308,Issaquah WA 98027, (206) 455-3990."

Circle 594 on i

iry card.

Universal Emulator Features Flexible Assembler

This Z-80 based development systemcombines a flexible assembler with amemory emulation module to provide a

development system for any micro-processor. The assembler can handlearbitrary instruction mnemonics in-cluding multibyte op codes like those ofthe Z-80. The assembler's symbol tablecan be set up with the mnemonics for an8080, 6800, F8, etc, and programs forthe selected microprocessor can then beassembled. The system comes with aZ-80 processor, 32 K bytes of memory,4 K bytes of emulator memory, and adual drive floppy disk. An operatingsystem, editor, assembler and utilitiesarc provided. Also included are up tofour buffered connectors which aredesigned to plug into 2708 EROMsockets in the target system. Priced at$5995, the emulator is available from .M & E Associates, 10439 N Stelling Rd,Cupertino CA 95014."

Protect Circuit Boards with TheseConductive Bags

LI', tl

','f 1 I I I

CP302 Statfree Conductive Bags aremade of electrically conductive non-woven nylon material to protect MOS,CMOS and other sensitive electroniccomponents from static electricity. Thebags come in sizes from 5 by 8 inches(12.7 by 20.32 cm) to 10 by 18 inches(25.4 by 45.72 cm) and have a tensilestrength in excess of 7500 pounds persquare inch. The manufacturer willimprint a company name and modelnumber on the bags. Prices start at$21.50 per 100 bags, from CharleswaterProducts Inc, 3 Walnut Park, WellesleyMA 02181, (617) 237-5942."

Circle 596 on inquiry card.

Dual Density Floppy Controller Chip

Circle 695 on i

ry card.

The FD1781 floppy disk controllerand formatter chip is completely com-patible with TTL and will accommodatethe interface systems of most disk manu-facturers. Its features include automatictrack seek with verification, selectabletrack to track stepping, head settlingand engage times, double buffering ofdata, and an 8 bit bidirectional businterface for communication with thecomputer. It provides data, data strobeand address mark IO for reading andwriting data and can handle a varietyof encoding and formatting methods.The FD1781 is available from WesternDigital Corp, 3128 Red Hill Av, NewportBeach CA 92663, (714) 557-3550."

Circle 597 on inquiry card.

216

BYTL March 1978

ASCII KEYBOARD ...

With direct addressable interface to S-100 or other bus

or ... complete VIDEO TERMINAL

Can all be housed in attractive

enclosure below

FEATURES

49 keys plus space bar, shift, and shift lock.

linimum 10 additional keys for control, lower case,system reset, etc. (some illuminated).

Outputs TTL compatible.

Keyboard interface is tri-state; address decodingcapability eliminates need for external I/O board.

Serial board (w/RS232 interface) or complete videoterminal fits into cabinet under keyboard.

Single supply voltage (plus 12V or plus 5V), less than150 mils drain.

Excellent commercial quality (manufactured by Cherry).

Attractive, sturdy cabinet in simulated walnut and blackvinyl.

Through a fortunate purchase of new and used surplus keyboards, coupledwith some imaginative design, we are able to offer professional quality I/Ocapabilities for any minicomputer system or for use as a stand-alone remoteterminal. Simply add a video monitor (or converted TV set) and save atleast 50% by buying one of the keyboard-video interface combinationsdescribed below.

KEYBOARD ONLY $ 44.95

Above configured to serve as addressable input

port with cable 54.95

Above, as direct plug-in to the S-100 bus 69.95

Keyboard with serial board incl. RS232 interface ... 84.95

Keyboard with complete video terminal (adapted version ofESAT-100), 16x32 format - 2 pages, with serial interfacefrom 300 to 9600 baud (conversion kit to 16x64 will beavailable), full cursor control, kit 199.95

Above, built and tested 249.95

With 16x64 video board (adapted version of Xitex's SCT-100)upper and lower case, 128 characters, with both serialASCII and BAUDOT capabilities, full X-Y cursor control,kit 249.00

Above, built and tested 299.95

With 24 x 80 video board (adapted version of Dynabyte 57),upper and lower case, addressable cursor and blockmode editing, built and tested 399.95

Above units are supplied as stand-alone units. For directinterface to system bus ADD $ 10.00

When interfaced to an S-100 bus, video board can be in main cabinet

for service convenience. Please specify use.

Reconditioned 12-inch 14 MHz monitors $ 109.95

New monitors and modems available.

Keyboards without interface or case — available at greatlyreduced prices.

Above keyboards are used, in excellent condition, andare guaranteed for 90 days. Limited quantity of new units

available — ADD $30.00 to any of above prices.

Add $2.00 for handling, shipping, and insurance.

Send for free 64-page catalog of other values.

MiniMJCroMart, Inc. 1618 James Street, Syracuse, N.Y. 13203 (315)422-4467

Circle 74 on inquiry card.

What's New?

XOFF Junk Characters Forever

Make Printed Circuit Boardswith This Film

This film can be used withoutcameras or chemicals to make printedcircuit boards, component placementdecals, front panel faces and similarpatterns directly from a printed pageas in a magazine construction article. Asix step process is used to complete atransfer in less than 15 minutes. Pricesfor the film range from $5.49 for asmall package of six 4 by 6 inch (10.16by 15.24 cm) pieces to $7.95 for alarge package of three 9 by 12 inch(22.86 by 30.48 cm) pieces, fromPrinted Circuit Products Co, POB4034, Helena MT 59601."

Circle 598 on inquirv card.

Wrap Your Own with These Rolls

Industrial quality AWG30 wire wrap-ping wire is now available in convenient50 foot rolls on 1 5/8 inch diameterspools. The wire comes in four colors,red, white, blue and yellow, from OKMachine and Tool Corp, 3455 ConnerSt, Bronx NY 10475, (212) 944-6600."

Circle 599 on inquiry card.

Hand Held Speech Synthesizer

The Phonic Mirror HandiVoice handheld speech synthesizer enablesvocally impaired individuals to talk.The device produces phonemes ratherthan words and hence can articulatevirtually any English word through somecombination of phonemes. Two modelsof the synthesizer are available: the HC120 which features a numeric keyboardand liquid crystal display, similar to apocket calculator, with vocabulary se-lections made via three digit codes,designed for individuals with lowermotor skills and higher cognitive skills,and the HC 110, which features a touchsensitive display board with 128 stationsrepresenting words, pictures or symbols,designed for individuals with lowercognitive skills and higher motor skills.The synthesizer electronics were ori-ginally developed for industrial use byVotrax, a division of Federal ScrewWorks. Sold only after referral by aprofessional speech pathologist or thera-pist, special education teacher or physi-cian, the Phonic Mirror HandiVoice ismanufactured by HC Electronics Inc, adivision of American Hospital SupplyCorp, One American Plz, Evanston IL60201,(312) 866-4237."

Circle 600 on inquiry card.

Radio Shack Offers the 8080A

That old stalwart, the 8080A micro-processor chip, can now be purchased inRadio Shack stores around the countryas stock number 276-2510 (most likelyin a bubble pack). The 100% primechip is priced at $17.95. This fact likenothing else symbolizes the micro-processor's penetration into the every-day world of consumer electronics."

This smart motor control allows aTeletype to print and punch paper tapewithout producing junk charactersduring an on-off cycle. The Model TR20is an external motor control with a sixcharacter storage capability that providesa 0.6 second delay for the Teletypemotor to speed up and print. The unitmounts by magnet to the Teletypepedestal. It connects directly to themotor through a fuse plug device anddoes not interfere with the optionspanel. The Model TR20 features a by-pass switch to permit standard keyboardoperation. An adjustable timer providesup to a 20 second turnoff delay. Theunit is 6 by 3.5 by 3 inches (15.2 by 8.9by 7.6 cm), weighs one pound andoperates on 110V current.

The Model TR20 is guaranteed fortwo years and sells for $175 from DigitalLaboratories, 600 Pleasant St, Water-town MA 02172, (617) 924-1680."

Circle 602 on inquiry card.

New TV Interface RF ModulatorHandles Color and Sound

The Pixie-Plexer Model PXP-4500 isa special RF modulator for multiplex-ing and interfacing color and luminancevideo signals plus audio to any TV setthrough the antenna terminals. Featuresinclude a 3.5 MHz color subcarrier oscil-lator and a 4.5 MHz audio subcarriercomplete with varactor diode modulatorfor FM sound insertion. The PXP-4500may be operated as a simple mono-chrome character display or a multi-plexer plus modulator for color dif-ference inputs and audio subcarriersignals. The device is built from a singleintegrated circuit on a 1.5 by 3 inch(3.81 by 7.62 cm) board with printedcircuit RF coils. A single 15 V powersupply (optionally -12 V and 5 V)at 50 mA is required. The kit comescomplete with assembly instructionsand a data sheet on the integratedcircuit. The PXP-4500 is $24.50 fromcomputer stores nationwide or directfrom the manufacturer, ATV Research,13th and Broadway, Dakota City NB68731,(402)987-3771."

Circle 601 on inquiry card.

Circle 603 on inquiry card.

218

BYTE March 1978

POLYPAKS

COMPUTER PERIPHEKAL&PARTS W€RttSHCP

POLY PAKS INTRODUCES THE FIRST MAGAZINE RETAIL STOREFOR THE ELECTRONIC MAIL-ORDER HOBBYIST.'

MAILORDER

fCwycxIriclrtrlrrtrCwycJrwIcww

t "RED" LED READOUTS!

| ■• i<>« •• 201 each

Cat. No.

□ 3S1890 .1

D 3S1503 .1

03S1273 J

D3S3093 3

a 3S3161 3

u 3S3512 3

)352949 3

a 3S29S0 3

a 3S3483 3

a 3S2485 3

o 3S2256 3

'Common Anode

Description Sale

M»N-3" 5 lor $1.00

MAN-4* 2 for

MAN-1'MAN-72 equal*MAN-74 equal"FN0339"FHD500-FN0507'727-Oual"727-Duel'747""Common Cathode

' SI.19$1.00$1.19$1.19$1.00

J 1301.50S.5030$1.95

AND CONTROL ^ g* i^,

KEYBOARD KIT! 29 Iffii

Wt. 2lb».

HEXADECIMAL MICROPROCESSOR

Address

microprocessors,control computer operatedequipment 2 key rollover. Has20keys. 16encoded, 4externaltobe assigned by user. Output 4 bitbinary. Also, an EXCLUSIVEFEATURE... 4 leds display thebinary output TTL/CMOScompatible, requires +5,12VDC. Complete kit! Nothing Cut. No. 3S5009 Hexadecimal Kit $29.95else to buy! With instructions. Cat. Mo. 3S5010 Hexadecimal Wired $34.95

• 4 bit binary/hexadecimal output plus strobe!

• New! Improved design! Saves you time!

• Keyboard pro-assembled onto PC board!

■tck'k-kirirk'irk-trlrtrk ■to'iririckiciiltielcltitiriticiilririt'itlt

DISCRETE LED'S

Order In multiples 0 3S213S

of 6 of each typo! a 3S1944

0 35213S

□ JUMBO .34" h a 342785

□ MEDIUM .24" o «2137DMICRO .21" a 3S1949

(TO-1S) D 3S2140

6 for $1.19

Description Similar toJumbo Rod MV50S3Jumbo Yellow XC55SYJumbo Groan XCSS6GMedium Rod XC22

Medium Green XC22GMicro Rod XC209

Micro Yellow XC209YMicro Green XC290G

KETBOARD&ENCODER KIT

COMPUTERGRADE

Mfd WVCD

o 8,000 50

o 13,000 40

•CAPACITORS^ UlSSS ?S

! Order by Cat. No. ° J^.OOO 75

! 355112 and,alue! ° "•?" IS

Sale a

$2.75 a

2.25;

2.75 ;

1.50 ■

3.95 "

230 ■

3.95 »

Cat. No. 3S5O01 Kit $49.95

Cat. No. 3SS0O2 wired $59.95

Outputs standard 7 bit ASCII; interfaces with most data systems, e Uses MOS Encoder ROM!

Keyboard pre-assembled onto PC board. 2 key rollover. Electronic e 7 LED Tost Feature!

shift lock and carriage return. 4 modes: Normal, control, shift, e 64 key keyboard'

shift/control. Additional functions can be assigned by user. +5. - » Fnrnrf..iH acril rh.nri.n1

12Vl)C. 200 ma. Negativeor positive logic, jtimpe^selcctable. J ^JJJ*e,, J|f,TaLTAIR™ !

logic

i's display the' ASCII —

Complete kit, nothing else to buy! Size: 13" x 5 1/2 x 1 1/4". 3 lbs.

IMSAI, and more!

Low Power ICs $

nroTrTnnrYirr.nnn.-v^

tm BRIDGE RECTIFIERS! §

2 AMP 6 AMP

Order Ry Cat. No. 3S3667 A Type No.

WAVE

PIV (03S1346)(0352456)(#352447)(S3S2273) R3 $0 $ .59 $ .88 $1.05 $1.20 H

n 1001 o 200I o 400

1.19

1.401.691.95

2.2S

1.151.291.791.9S22$2.S0

1.251.952.953.95

4.955.50

Orer by Cat. No. Amperage and Voltage

SPECTRA-TWIST • ™*}*} ^J1™10JArij£t,>

nrnn/.U colored cablel 24AWG

iM »w^. H CaL No- 3S3680 48 corn). 2 ft $1.96CABLE O Cat No. 3S4081 32 com). 2 ft $1.98

RIBBON CABLEAT THIN PRICES

• Ultra-flat! e 28 AW6!

• Single color! Indexed! "w a n. >i.ya p ■Order by Cat No. 3S3939 and conductor* g

Type

□ 74LS00

□ 74LS02D 74LS04Q 74LS08D 74LS10a 74L511D 74LS13D 74LS20

□ 74LS21C 74LS22D 74LS27D 74LS30D 74LS32C 74LS37C 74LS38C 74LS42E 74LS47E 74LS74C 74LS90

□ 74LS92a 74LS93D 74LS109Q 74LS112D 74LS113

□ 74LS114

Sale

$.32

.32

■™ h

Typo

□ 74LS13211 74LS138O 74LS139D 74LS151Q 74LS153D 74LS15SQ 74LS160D 74LS161G 74L5182D 74L5163Q 74LS1G8C 74LS169

□ 74LS173a 74LS174D 74LS190P 74LS191D 74LS192D 74LS193D 74LS19SD 74LS197Q 74L52S7

□ 74LS26Ga 74L5366D 74LS368D 74LS390

Sale1.191.241.24

1.251.251.251.471.471.471.471.G81.681.681.051.771.751.751.751.251.251.35

.54.

.66

C-MOS

Order By Cat.352320 &Typ

No.

)No.

Typo

Sale

Typo

Sale

D CD4000

$.29

1 1

CD4022

1.19

r

CD4001

.29

1 1

CD4023

.29

1

CD4002

.29

1 |

CD4024

.79

1

CD4006

1.19

1 1

CD4025

.34

CD4007

.29

1 1

CD4027

.69

i

CD4008

.79

1 1

CD4028

.89

i

CD4009

.59

1 1

CD4029

1.19

i

CD4010

.59

1 |

CD4O30

.49

i

CD4011

.29

1 1

CD4033

1.60

1

CD4012

.29

1 1

CD4035

.99

i

CD4013

.69

1 I

CD4040

1.19

i

CD4015

1.19

1 1

CD4041

1.25

i

CD4016

.49

1 1

CD4042

.88

i

CD4017

1.19

1 1

CD4046

1.79

i

CD4018

1.19

1 1

CD4049

.49

L

CD4019

.49

1 1

CD4066

.79

D CD4020

.99

II

CD4071

.29

□ CD4021

1.29

MICROPROCESSORS!MEMORIES! SUPPORT!

Order by Cat. No. 3S34S9 and type

Type Description Sale

d [MC6800L 8 bit CPU $24.95

n 8080A 8 bit CPU, 2 usee 14.95

□ Z80A 8 bit CPU 34.95

D 8008 CPU 9.95

□ 1101 256 x 1 stat. RAM 69

□ 1103 IK Dyn RAM 1.29

a 1702A 256x8EPR0M 5.9S

a 2102-L1 IK x 1 La-power RAM 1.69

□ 2111 256 x 4 Stat. RAM 5.95

□ 2708 8K EPROM 19.95

□ MK4116 16KDynRAM 32.00

□ MK42O0P11 4K x 1 Dyn RAM, 350nsec 3.95

o MM5202 2K PROM 6.9S

a MM5203 2K EPROM 8.95

□ MM5260 IK Dyn RAM .99

n MM5262 2K x 1 Dyn RAM 99

0 8212 8 bit I/O port 3.95

a 8216 Bi-direct bus driver 3.95

a 8224 Clock Gen 4.95

o 8228 System cont 9.95

□ B251 Communication int 11.50

□ 82S5 Periph Inter 11.95

♦♦♦♦*♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦**♦

TTL'S

SPECTROL "SKINNY-TRIMS"

3/8" square, screwdriver shaft, Your Choice2% tol. 1/4 watt. Cermet PC -. _ -._leads. Order by Cat. No. and 2 TOr $1a IK □ 10K value.

o 2K o 20K O Cat No. 353863 25 turn upright type 64□ 5Ko SON CCat. N0.3S3866 single turn, Sat type 63

OhmsD SOo 100□ ISO

10 AMP POWER TAB SCR'S, pivTRIACS, QVABRACS! CatNo.

Order by Cat. No.and Voltage

SALE

□ 50 $.55o 100SCR'S 3S1730 a 200

TRIACS . 351448 a 400 1.19QUAORACS 3S1590 a 600 139

POLY PAKS "CHIPS" AWAYIC AND CRYSTAL PRICES!

Order by Cat No. 3S404S and Type No!

Typo Description Sale

DICM720S Stopw.tch $14.95

aAY3-85O0-l 6 TV Games 9.9S

OMM5330 tv. Digit DVM 4.95

□ 8038C Volt Control Osc 4.95

OKR2376-139 BCD Encoder Rom 6.95

OKR2376-ST ASCII Encoder Rom 14.99

O11C90DC 650MHI Prescaler 14.9S

O95H90DC 350MHz Prescaler 8.88

OMC14410 Touch Tone Chip 9.95

OMK2002P Cher Gen. (slm 2513) 3.95

O7207A/7208 Freq Counter pair 24.95

MCM7107 3'i Digit DVM/DMM 1230

DMMS316 Alarm Clock 2.95

□MM5369 60 Hz Tlmobase IC 1.95

o3.579MHi Tlmobase Xtal 1.95

□ 1.00MHz Touchtone Xtal 5.95

o3.2768MHz Stopwatch Xtal 4.95

■■■■■•■eaeaeaeeaeieeaaeaeaeeeeeeeeeei

MOTHERBOARD

EDGE CONNECTQF

D

$3.95

106 pins (53 each side).Use with 1MSA1 & ALTAIRI0.12B" pin ctrs, goldplatedVs" wire wrap leads. Openends, fit wide PC boards.& oss.Cat No. 3S3987

sssssssssssssssssssssss—— ^ Contacts Sale

GIAHTS»UBMICRMJJHi = ^ sPST $>■"

TOCCLE SWITCHES ns|40j|SfDT |

•-AUTOPATCH ENCODER KIT.

1N4000 EPOXY RECTIFIERS

• Miniature!

• 1.3 Amp!

Cat. No.

J 3S2377

1 352378

J 352379

J 3S23B0

Type No. PIV

1N4001 50

1N4002 100

1N4003 200

1N4004 400

1N4005 600

1N4006 800

Sale

10 for $.6510 for .7510 for .8510 for .9910 for 1.2910 for 1.39

SILICON POWERSTUD RECTIFIERS!

Order by Cat No. Amperage and voltage.

12 AMP SO AMP 250 AMP

PIV (S3E727) (S3S727) (S3S685)

□ SO $ .29 $ .75 $4.95

□ 100 .36 1.10 6.50

□ 200 AS 1.3S 7.50

□ 400 .61 1.7S 830

□ 600 .79 2.25 10.50

□ 900 .90 2.7$ 1130

SOLAR ENERGY DISCS

•*» Cells 3V! A. low .,$3.95

• High efficiency! ^** T"*

• Gang for higher voltages end amp*!

Cat. No.a 3S5046

□ 3S3S62

□ 3S3788

□ 35 5057

Size

SOOme100 Oma

1200meISOOma

Sale$3.95

838123015.95

DIP SWITCHES

Cat. No.

□ 3S3668

□ 3S3669a 3S3021a 3S3G70D 3S3G71a 3S2677

«, Type

♦ □ SN74O0

♦ □ SN7401

♦ □ SN7402

♦ d SN7403

♦ □ SN7404

♦ a SN740S

♦ a SN7406I ° SN7407I n SN7408I a SN7410

♦ i.i SN7411

♦ □ SN7413

♦ a SN7414

♦ a SN7417

♦ 0 SN7420

♦ o SN7427

♦ 0 SN7430I n SN7432I O SN7437

♦ a SN7440

♦ □ SN7441

♦ a SN7442

♦ a SN7445

♦ a SN7446

♦ a SN7447

♦ □ SN7448

♦ a SN7450

♦ o SN7451

♦ a 5N7470

a SN7472a SN7473a SN7474a SN7475

□ SN7476

□ SN7483d SN7485a SN7486

□ SN7490

□ SN7492a SN7493

□ SN741070 SN74121

□ SN74123n 5N7412S0 SN74132

□ SN74145

□ SN74151a SN74153a SN74154d SN74157o SN74161

□ SN74164

□ SN74174D SN7417S

□ SN74181

□ SN74190d SN7419ID SN74192

□ SN74193

□ 5N74195n SN74251

1.9S

1.15.99

♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦*♦♦♦♦♦♦♦♦♦

********* l IN EARS *********

EECO 10-POSIT.ON BCDTHUMBWHEEL SWITCH

1-2-4-8 BCD encoding!- ,Positions labeled 0-7, ¥, L.I3 »or(F coded for 8. L coded for 14.9). White numerals on a _

black background. Eeco 800 \ |

aerie.s. I1/* x I1/* x 1/2".|T'i Jtt%Cat. No. 3S384B 3>X ■•4"

* Type

* D LH301H, V

f □ LM307H, V, N£ d LM308H, VI □ LM309KI Q LM311H.VI □ LM320T-5VX|o LM320T-1SVX a LM320K-12V$ Q LM320H 1SV-K □ LM340T-5V+ □ LM340T-12V+ d LM340T-15Vf a LM340K-SVf q LM340K-12Vf a LM340K-15Vf a LM322Nt a LM324N£ >=> LM339Ni a LM377N

S«le$.25.25

LM379ND LM380No LM381N

□ LM555V

□ LM5S8V

□ LM56SNo LM567Vo LM703H

□ LM709H, Nn LM710N

□ LM723N

a LM741H, V, NO LM747H, N

□ LM1458 V

□ LM1800N

□ LM3900N

□ LM 39009Vn LM75491a LM75492

□ PA263

4.95*1.19*1.19*

.44?

.69 I

-65 I1^0 I

.39 k

jam

.29*■42*.29*.59 J.69J

1^491.35$

1.19 X.69?.75*

1.50*

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

..nltylE e Frtendsl

II e Compart* 1" ^^ n■ Hs own m«iK*W~«1 u

8LteHEs£Sr

ITRANSFORMERSALE ^..ee.),.

10OK/

110VAC Primaries

■ k, buy! Wt 12 os.

',!■■■ ■■■■■■■yu-n i

COPYRIGHT 197B - POLY PAKS INC.

Cat. No.D, 353399G 3S3B14D 353412Q 35 4 029D, 3S4028a 35 3323□ 35 3937D! 35 2773Ql 3S387S

Output V.

6.3 V

6..IV

12V

12V

12V

24VGT

24V

•18VCT

110V

■■■■■■■■■■a

ma Metal encasedOpen frame

ma Open frameOpen frameMetftl encased

iia Open frameOpen frameMetal encased

mi Isolation

■ ■■ ■■

Sale ■

Each ■

51.98 ■

$2.49 ■

$1.95 ■

$2.49 .

$2.95 "

$1.95 "

$1.95 ■

$2.95 ■

$1.19 ■

COMPUTER GRAPHICS 2<or$s.

MOYSllCK,' o $4.50

'zmin

Bfffl HASTDT COMPUTER IHIXTITESTER

1000 ohms per volt

1 % precision, movementsdiode protected againstburnout. Meaaures DC volts0-15-150-1000; AC volts0-15-150-1000; DC current0-1 SOma; resistance X1000.Sensitivity 1000 ohms/voltAC-DC. Uses penlite cell,not Included. Size 2% x8Va x 1V„". Wt. 5 ozb.Cat. No. 353921

♦ IC SOCKETS ♦

♦ »'owaB'17^ea ♦

♦ r, * L« * proW*' «*'••• tan. ♦

♦♦:

WRITE FOR

POLY PAKS1CATALOG

FEATURING

BEST BARGAINS

IN ELECTRONICSTerms: Add postage Rated: net 30Phone : Wakefield, Mass. (617) 245-3829Retell: 16-18 Del Carmine St.. Wakefield.MINIMUM ORDER — $6.00

POLY PAKS

r&pSSMlYl «•■.<>. BOX 942S

Circle 96 on inquiry card.

BYTE March 1978

219

What's New?

Logic Analyzer Plugs IntoAltair (S-100) Bus

The Model 150 "Bus Grabber" logicanalyzer electrically and mechanically

interfaces to the Altair (S-100) bus,monitoring 56 key bus signals withoutthe need for the numerous and unwieldyinput probes associated with nondedi-cated instruments. Included in the 56signals are the address and data bus andthe microprocessor status, interrupts andcontrol signals. In addition to the 56dedicated signals, eight user definedsignals interface to the plug-in boafdthrough an optional flat ribbon assembly.The associated probe tips can be usedwith ball clips, wire wrap pins or inte-grated circuit clips on any kind of equip-ment. Triggering of up to 24 bits, displayformatting and operational modes of thelogic analyzer are controlled from asmall hand held pod connected to the

plug in board through a ribbon cable.Data "grabbed" from the Altair (S-100)bus or other signals are displayed as onesand zeroes on an ordinary oscilloscopeconnected through the horizontal, verti-cal and (optionally) blanking inputs.Signals can be captured and stored in theanalyzer's 16 bit wide by 16 word deepdata memory and displayed on the oscil-loscope as a series of eight truth tables,each 8 bits wide by 16 words deep.Data can also be formatted into hexa-decimal and octal binary groupings.Other features include automatic clockqualification and clock polarity selection,and choice of pre or post trigger dataacquisition.

The Model 150 logic analyzer isavailable in kit form for $369 or assem-bled for $449, with an optional external8 bit probe set for $9.95, from Para-tronics Inc, 800 Charcot Av, San JoseCA 95131,(408) 263-2252.»

Circle 624 on inquiry card.

New Probe for Capacitance Meter

This chip probe for ECD CorpC-Meter expands the capability of thehand held 3-1/2 digit battery operatedcapacitance meter to function as aunique inexpensive portable measuring

tool for chip capacitors. Costing $39, thechip probe consists of a pair of tweezersconnected to a double banana plug by asmall diameter coaxial cable. The probeplugs directly into the C-Meter's standardbanana jack input terminal. The cablecapacitance is cancelled by the C-Meter"offset adjustment" located on the frontpanel. Connection to the chip capacitorterminals is made simply by permittingthe tweezer tines to touch the capacitorterminal ends. The probe is designed foruse with chips whose terminal spacing isfrom 0.02 inches to 0.300 inches andwith values greater than 0.1 picofarads.The ECD C-Meter, which features auto-ranging, measures from 0.1 picofarads to200,000 microfarads and automaticallyindicates the capacitor's value on itslarge LCD display. The C-Meter is $289from ECD Corp, 196 Broadway, Cam-bridge MA 021 39."

Circle 625 on inquiry card.

Millennium Arrives in Logic Analyzers

In Circuit Debugging forCOSMAC Based Systems

/

m

n

^$^:

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^ "^

^3^

^^^^^^*

The CDP18S030 COSMAC Micro-monitor is a hardware and software de-bugging tool which can be attached bymeans of a single cable connection to thesystem under test. Controlled by its ownmicroprocessor, the device uses the 1802processor, power supply, clock, memoryand other components of the systemunder test to run a user program. TheMicromonitor provides an extensive setof debugging facilities, including 43 com-mands to examine and modify registersand memory, set breakpoints based onflag lines, interrupts and memory re-quests, and run the program in fullspeed, single instruction orsingle machinecycle modes. Sell-contained in an attachecase, the Micromonitor includes a builtin keyboard, display and status indicatorlights. It is priced at $1600 in singlequantities and is described in the PD18brochure from RCA Solid Stale Division,POB 3200, Somerville NJ 08876."

Circle 627 on inquiry cord.

This diagnostic tool is designed toallow technicians of limited skill toisolate component faults in micro-processor based products. The Micro-system Analyzer combines signatureanalysis with a circuit emulation to easetroubleshooting of complex products.An umbilical cord is plugged into themicroprocessor socket of the systemunder test, and bit patterns are generatedwhich cause predictable bit streams toappear at various points in the system.The analyzer is designed for universaluse, by incorporating one processor foroperator interaction functions and asecond processor for functions relatedto the system under test. Operator inter-action is carried out through a functionoriented keyboard and a 20 characteralphanumeric display. Test programsmay be keyed into the unit's program-mable memory or stored in read onlymemory chips which can be pluggedinto the unit. The unit's mother boardand card cage provide room for optionalexpansion boards. Options include a realtime trace feature and an RS232 connec-tion for remote use. The MicrosystemAnalyzer is priced at $2475, while thesignature analysis probe option is $495,from Millennium Systems Inc, 19020Pruneridge Av, Cupertino CA 95014,(408) 966-9109.■

Circle 626 on inquiry card.

220

BYTE March 1978

so,

ea,

GOLD WIREWRAP SOCKETS!

25-49 50-991

tool

lilt

BOARD

8 pin

.47

10 pin

16 pin

118 pin

120 pin

122 pin

|24pin

128 pin

|36pin

|40 pin

•042 dia holes or0-1 spacing for ic's

nice

« 1.49» 3.51

MICEI 1.70» 2.10* 4.30I U

sena

UY "

JJ* 473 ™ -

p«0,

"00

:o^

c°pp,

e'«a,

3677 9 6" X 4.5

$10.90

3677-2 6.5" «4.S"

$9.74

Gen. Purpose D.I.P.Boards with Bus Patternlor Solder or Wire Wrap.Epoxy Glass 1/16" 44pin con. spaced .156

pro*

PRIORITY TONE I ELECTRONICS

P031 Woodley Ae» Sepulx^da CA, 91343

Terms: VISA, MC. BAC. check. Money Order. COD.. U.S. Funds Only. CA residents add 6% sales tax. Mini-*mum order $10.00. Orders less than $75.00 include 10% shipping and handling; excess retunded. Just in case. . . please include your phone no. "Sorry, no over Hie counter sales" Gaod ,hro APril ,5',978

Send for our iBtesI brochure. ph0ll6 Orders WBlCOiTie (213) 893-8202 OEM and Instllutional inquiries invited.J

IE£tl&

Circle 97 on inquiry card.

BYTE March 1978

221

CSIsssified Ads

FOR SALE: 4 K programmable memory printedcircuit boards for 2102 type memories (andothers). Brand new commercially made boardswith plated thru holes and gold fingers. I haveabout six extras to sell at 2 for $15, with diagramand edge connector, postpaid, money order please.Steve Kelley. 9506 Peach St, Oakland CA 94603.

16 BIT FREAKS: Interested in saving $50 on thenew Texas Instruments Tm 990/100m-1 16 bitmicrocomputer module? It is factory assembledand has programmable memory, Rom monitor,serial and parallel interface, and fully bufferedexpansion bus. See photo on page 218 in Septem-ber BYTE. For more information contact J EBrancheau, POB 67, Trenton Ml 48183.

FOR SALE: IBM 5100 with APL, 48 K, serial IO,5103 printer, current IBM service contract. Was$18,450 new. Asking $16,950. Peter Goltra, Rt 2,Box 31, Middleburg VA 22117, (703) 687-6976.

FOR SALE: IMSAI 8080 with 4 K IMSAI pro-grammable memory, 22 slot motherboard, IBMSelectric IO writer, and REMEX high speed papertape reader. $950. Jeffrey Borish, 1669WhitwoodLn, Apt 3, Campbell CA 95008, (408) 379-8278evenings.

SOFTWARE: Exchange. North Star Disc MediaLet's swap. Send SASE to HBR, POB AF, Wood-bridge CT 06525.

FOR SALE: HP-97 Calculator, $525, with box ofpaper rolls and all fresh magnetic cards. Absolutelyclean, 100% functional, still in warranty. BrewerPedin, 4307 Wyncliff Dr, Richmond VA 23235,(804) 272-6291.

FOR SALE: Microcomputer, Mostek F8, docu-mentation, regulated (5 V, 2 A; 12 V, 1 A) supply,RS232 to 20 mA circuit. In top condition. Makean offer. Paul Snigier, 360 Pleasant St, RaynhamMA 02767, (617) 822-1329 evenings.

WANTED: BYTE #2, October 1975. Will trademint condition #1, September 1975, or #13,September 1976, or pay cash. D Kenney, 82 FifthAv, Westbury NY 11590, (516) 334-7362.

FOR SALE: All issues of BYTE from September1975 to August 1977, except for December 1976.Best offer within one month after ad's appearance.Stephen Douglass, 348 Edgemeer PI, Oberlin OH44074, (216) 775-2492.

I NEED HELP! I need schematics, electrical specsand operating or technical manual for a Friden7102 Communications Terminal. I will buy themanuals or pay for copies. My terminal has twoboards missing. Has anyone any extras? M DeanKlingler, POB 930, Rialto CA 92376.

WILL SWAP: Pentax Spotmatic single lens reflexcamera with built-in automatic metering, Pentax f:1.4 50 mm normal lens plus Sun 38-90 mm zoomlens for Altair 8800, IMSAI 8080, SwTPC 6800,or similar minicomputer. Roger T Stevens, 5301Rawlings Rd NE, Albuquerque NM 87111.

Readers who have equipment, software or other itemsto buy', sell or swap should send in a clearly typed noticeto that effect. To be considered for publication, an adver-tisement should be clearly noncommercial, typed doublespaced on plain white paper, and include complete nameand address information. These notices are free of chargeand will be printed one time only on a space availablebasis. Insertions should be limited to 100 words or less.Notices can be accepted from individuals or bona fidecomputer users clubs only. We can engage in no corres-pondence on these and your confirmation of placementis appearance in an issue of BYTE.

Please note that it may take three or four months foran ad to appear in the magazine. ■

FOR SALE: One fully assembled and fully opera-tional SOL-PC with SOLOS operating system. Alldocumentation and software (BASIC, GAMEPACI) included, $600. Contact R Coates, 3508 SEWashington St, Portland OR 97214.

WANTED: Univac 0769-06 printer service manualcontaining exploded mechanical diagrams withpart numbers, schematic of -06 drive and interfacecard, timing information, etc. Will pay reasonableprice or copy charge. Also want commercial cabi-net or enclosure for this machine, or exceptionalhomemade one. Anyone out there in BYTE landhave any of the above, or know of any? LeroyLawler, 3101 Justin Way, Concord CA 94520.

PROM PROGRAMMING: From binary or hexa-decimal paper tape: 1702A ($4), 2708 ($8). Fromhexadecimal or octal listing: 1702A ($5), 2708($16). You supply the PROM. I have a few 1702APROMS available at $6 each. Quantity discountson programming. 48 hour turnaround. H S Corbin,11704 Ibsen Dr, Rockville MD 20852, (301)881-7571.

FOR SALE: Ohio Scientific, OSI Challenger, with12 K fast programmable memory, 440B videoboard, 430B cassette interface, 20 mil TTY port.With extras: memory board, CPU board, IO board,480 backplane, ASCII keyboard, full manual setwith all MOS manuals. Software includes: 8 KBASIC on cassette and paper tape (by Microsoft),4 K miniBASIC on cassette, OSI extended moni-tor, plus programs in BASIC. Much more. Take allfor $1200 or call for separate pricing and moredetails. Just plug in TV or monitor and go. Willship UPS in USA. Mark Gilger, 3306 S Maple,Rapid City SD 57701, (605) 342-4190.

WANTED: Information on IBM Model 11-C elec-tric typewriter. Also information on Clary ModelDE600 computer. Steven D Swift, 15302 5th NE,Seattle WA 98155.

1802: Instruction set summary for the 1802COSMAC, newly arranged in a compact, logical,typeset, 1 sheet format. Provides great aid for pro-gram writing and debugging, excellent introductionto what the 1802 can do (quite a lot!). Availablefor $1 plus SASE, from Seth McEvoy, Box 268,E Lansing Ml 48823. Uses RCA's instructions,operations and mnemonics.

FOR SALE: SONEX touch-tone computer termi-nal, $350. J Herrault, 645 Bush, Apt 307, SanFrancisco CA, (415) 391-9439.

FOR SALE: Litton, ABS 1210 decimal computer,drum memory 375 (10 digit) words. System in-cludes processor, drum, console and parallel IOASR 33. Price $1000 or offer. Roy, 8224 CalumetAv, Munster IN 46321, (219) 836-1222.

FOR SALE: Two 8 K Solid State Music memoryboards, 500 ns, static, plus spare ICs, all for $380.Color video recorder plus video camera and zoomlens, plus extra video cassettes; all for $400. LarryWright, Box 7576, Menlo Park CA 94025, (415)854-5678.

WANTED: 36 contact double sided PC board ex-tenders (total 72 contacts). Contact centers 0.2inch. Maximum card width 7-1/2 inches, preferable6 inches long. Also, Winchester Electronics MRE99 pin rectangular plug connector or equivalent.Both for Burroughs Agent Set. Gilbert R Bosse,Box 185, Riviere au Renard, Quebec CANADAGOE 2A0, (418) 269-3256.

FOR SALE: BYTE issues 1 thru 12, best offer.SwTPC CT-1024 TVT, complete with memoryboard and power supply, modified for 64 charac-ters and scrolling, all ICs in sockets, full documen-tation, $150 postpaid. A P Stumpf, Box 1603,Litchfield Park AZ 85340.

FOR SALE: Must sell due to move into.rotten oldhouse. Two Teletypes 33ASR (paper tape readerand punch with keyboard/printer). Both have beenused on IMSAI system. One has a Digital Equip-ment Corp (DEC) PDP-8 interface installed. Regu-lar TTY $675, PDP-8 interface TTY $725, plusshipping one high-speed paper tape reader Digi-tronics Model 2540. Can be used on two S-100parallel ports. Has an interface for a Data GeneralNova microcomputer. $900 plus shipping, one LearSiegler ADM-3 CRT terminal. Used regularly withIMSAI system. Upper and lower case option in-cluded. $775 plus shipping. One Anderson Jacob-son AJ841 Selectronic terminal. Used for hardcopywith IMSAI system. Uses EBCD encoding on key-board and Selectric printer. $950 plus shipping.Call or write: Ed Reich, 805 N Cleveland St,Arlington VA 22201, (703) 243-3131 evenings.

FOR SALE: Diablo Hytype II printer. Neverused. 8 111 inch pin feed platen, cover and bottomfeed. Interface to your 8080 or 6800. $1399 with-out power supply, $1799 with power supply.Roger Gersonde, 3950 N 54 St, Milwaukee Wl53216, (414) 462-1582.

FOR SALE: MCS 6502 resident assembler/texteditor (ASSM/TED). Syntax very similar to MOSTechnology. Produces relocatable object code ontape or executable object in memory. Relocatingloader program also provided. 17 commands and16 pseudo ops. User specifies memory area for textfile and symbol table, up to 10 characters per label,18 error codes, supports two tape decks, CRT andkeyboard and printer. Shipped preconfigured forTIM based systems but information is provided tomodify for others. Resides in less than 4 K (exclud-ing source file and symbol table) (0200-1200,0400-1400, 1000-2000, 2000-3000, please spec-ify). Hexadecimal listing and operator's manual,$25. C W Moser, 3239 Linda Dr, Winston-SalemNC 27106.

WANTED: Speech Lab kit or assembled board anddocumentation or manuals by themselves. Statecondition and price. H S Corbin, 11704 Ibsen Dr,Rockville MD 20852, (301) 881-7571.

WANTED: Information concerning the conversionof an SwTPC CT-1024 terminal to 64 charactersper line. Contact John Burns, 25th Floor, 350 ParkAv, New York 10022.

WANTED: Plotter, drum or bed, any size, any con-dition. Send complete description along with priceand/or trade requirements to Mark Sproul, 1368Noah Rd, North Brunswick NJ 08902.

FOR SALE: Hewlett-Packard Dymec Data Acqui-sition System. Model 2515A high speed digitalscanner; Model 2911 A guarded cross bar scanner;Model 2911B crossbar scanner control; Model2546A magnetic tape coupler; and Cook Model150, 7 track tape recorder. Above system, com-plete with manuals and rack, $300. Hewlett-Packard Model 5275A Time Interval Counter,$70. Will deliver within 100 miles or you payshipping. Donald Dorson, Gardner Rd, WestKingston Rl 02892, (401) 294-2190.

IS THERE LIFE ON THIS PLANET? What hap-pened to Life (as we know it)? Life is the cellularautomata developed by John Conway and de-scribed by Martin Gardner in Scientific American(I don't have the dates). Life is great fun, an intel-lectual pastime, and high powered math all rolledinto one. The possibilities with Conway's game areenough to keep you busy for a while, and, if thisshould pale, make up your own! Conway chose therules for his game; you can make your own. Whenyou do this, you have a completely new universe.In Life, the cells that determine the next genera-tion are adjacent to the cell in question. Theydon't have to be. Life is symmetrical. Try it someother way. Life is two-state. Make your own withfour states, each represented by a different char-acter (or color). Make an automata in which thenext generation is based on the preceding two gen-erations, instead of one. Each change produces anew universe to be explored. Two needs exist:people to create universes, and people to explore.I will serve as a Life clearinghouse, and if interestis shown, create a flyer. If interested, or you haveany information on Conway's game or others, letme know. Contact me. Rick Coates, 3508 SEWashington St, Portland OR 97214.

222 BYTE March 1978

S.D. SALES CO.

AN EMPIRE IND. CO.

P.O. BOX 28810B

DALLAS, TEXAS 75228

S.D. SALES NEWEXPANDABLE EPROM BOARD

16K or 32K EPROM $49.95 w/out EPROM

Allows you to use either 2708's for 16K ofEprom or 2716's for 32K of Eprom.KIT FEATURES:

1. All address lines & data lines buffered.

2. Quality plated through P.C. Board, in-cluding solder mask and silk screen.

3. Selectable wait states.

4. On board regulation provided.

5. All sockets provided w/board.

WE CAN SUPPLY 450ns 2708's AT $11.95WHEN PURCHASED WITH BOARD.

32K FOR $475 EXPANDORAM KIT 24K FOR $367.00

MEMORY CAPACITYMEMORY ADDRESSINGMEMORY WRITEPROTECTION8K, 18K, 24K, 32K using Mos-tek MK411S with 8K bound-aries and protection. UtilizesDIP switches. PC board comeswith sockets tor 32K operation.Orders now being accepted.Allow 6 to 8 weeks Tpr delivery

Buy an S100 compatible 8K Ram Board and upgrade the same board to a maximum of32K in steps of 8K at your option by merely purchasing more ram chips from S.D.Sales! At a guaranteed price — Look at the features we have built Into the board.

16K FOR $259.00

INTERFACE CAPABILITYControl, data and address in-puts utilizes low powerSchottky devices.POWER REQUIREMENTS+ 8VDC 400MA DC+ 18VDC4O0MADC-18VDC30MADCon board regulation is provid-ed. On board (invisible) refreshis provided with no wait statesor cycle stealing required.MEMORY ACCESS TIMEIS 375ns.Memory Cycle Time is 500ns.

8K FOR $151.00

Z-80 CPU BOARD KIT — $139.

CHECK THE ADVANCED FEATURES OF OUR 2-80CPU BOARD: Expanded set of 15S instructions. 8060Asoftware capability, operation from a single 5VDC powersupply; always stops on an Ml state, true sync generatedon card (a real plus feature!), dynamic refresh and NMIavailable, either 2MHZ or 4MHZ operation, quality doublesided plated through PC board; parts plus sockets pricedfor all ICs. 'Add $10 extra for Z—80A chip which allows4MHZoperation. Z—80 chip with Manual — 29 95

NEW FROM S.D."VERSAFLOPPY"™ KIT

THE VERSATILE FLOPPY DISK CONTROLLER

ONLY $149.00

Futurw: IBM 3740 Soft S«ctor»d Com p.. tibia. 8-100 INS Com-p* tibia for Z-80 or 80*0. Controls up to 4 DrtVM (singla ordouble tided). Directly contrail the following drive*:

1. Shugart SA4O0/4SO Mini Floppy.

2. Shugart SA800/IS0 Standard floppy.

3. PCRSCI 70 and 277.

4. MFE 700/750.

8. CDC 9404/9406.84 Pin Connector for Mini Floppy. 50 Pin Connector for StandardFloppy. Operate* with modified CP/M operating ty*t*m andC-Batlc Compiler.

The new "Versafloppy from S.D. Computer Products provide*comptete control for many of the available Floppy Disk Drive*,Both Mini and Full Sin. At the heart of "Veroafloppy" hi thepowerful Western Digital FD1771B-1 Single Denaity ControllerChip. Thli allows a great flexibility via Control Software. Deling*for Control Software are ncluded In the price.

FD 1771B-1 CHIP ALONE S39.95

4K LOW POWER RAM KIT

Fully Buffered — on board regulated —reduced power consumption utilizinglow power 21L02 — 1 500ns RAMS —Sockets provided for all ICs. Qualityplated through PC board 'Add $10. for250ns RAM operation.

The Whole Works - $79.95

Low Cost CassetteInterface Kit

WPf[

feeluna: Play art record K.C. Staneant 2400/1100 Kf

taps.. 300 Baud, TTL I/O CeatoattMe, Phase Lack Lacp.•etfi 22 Pin Connecter and 8 Pin aW« Daanectar.Comat partially luambied. OKiflatar and *e**e leekteoe pra-tuned to K.C. Standard. Sttadar awttcn send*ceasatla data w auxiliary lupwt data ta ■Itwanaeenir.LEO Indicates loflk 1 hwet.

-LJLIlIllillillllllULLb-

$19.95

6 DIGIT ALARM CLOCK KIT

Features: Litronix dual 1/2" displays, Mostek50250 super clock chip, single I.C. segmentdriver, SCR digit drivers. Kit includes all ne-cessary parts (except case). Xfmr optional.Eliminate the hassle. «i o qe

AC XFMR -$1.50 C«M $3.50 ?1*.»0

8K LOW POWER RAM — $159.95

Fully assembled and tested.Not a kit. Imsai — Altalr —S-100 Buss compatible, useslow power static 21L02-500nsfully buffered on board regulat-ed, quality plated through PCboard, including solder mask. 8pos. dip switches for addressselect.

DIGITAL LED READOUTTHERMOMETER - $29.95

Features: Litronix dual 1/2" displays.Uses Silicoaix LD131 singlechip CMOSA/D converter. Kit includes all neces-sary parts (except case); AC line cordand power supply included. 0-149* F.

Bowmar 4 Digit LED Readout ArrayFull 14" Litronix Jumbo DualDigit LED Displays

4 JUMBO .50" DIGITS ON ONE STICK!WITH COLONS & AM/PM INDICATOR.$3.95.

MUSICAL HORN

One tune supplied with each kit. Additional tunes — $6.95each. Special tunes available. Standard tunes now available: —Dixie — Eyes of Texas — On Wisconsin — Yankee DoodleDandy — Notre Dame — Pink Panther — Aggie War Song —Anchors Away — Never on Sunday — Yellow Rose of Texas —Deep In the Heart of Texas — Boomer Sooner — Bridge overRiver Kwai.

CAR & BOAT KIT HOME KIT Special Design

$34.95 $26.90 Case $3.50

Jumbo LED Car Clock Kit

FEATURES:

A. Bowmar Jumbo .5 inch LFD array.

B. MOSTEK — 50250 — Super clock chip.

C. On board precision crystal time base.

D. 12 or 24 hour Real Time format.

E. Perfect for cars, boats, vans, etc.

F. PC board and all parts (less case) inc.Alarm option — $1.50

AC XFMR - $1.50

$16.95

* * * *SUPER FLOPPY SPECIAL* * * *|

S. D. SALES, VERSAFLOPPY S-100 CONTROLLER BOARD PLUSSHUGART SA 400 FLOPPY DISK DRIVE INCLUDING CABLE FOR ONLY

$479.00

MICRO-DIP $1.95

• New - Series 2300The World's SmallestCoded BCD Dual-ln-LlneSwitch! PC Mount2300 02G BCD 1-2-4-82300 12G BCD 1-2-4-8 Compliment

• •JOYSTICKS* •

FOUR 100 K-OHMS

POTS >Ideal for f.«rj!

S3.95

electronicgames

1702A - IK - l.Sut . .3.95 or 10/35.

2708 ■ 8K - 450m 14.95

5204 -4K 7.95

82S129 — IK 2.50

2708U 8K signifies 650ns 9.95

MK50397 6 Digit elipsed timer . 8.95

MK50250 Alarm clock 4.99

MK5038O Alarm chip 2.95

MK50395 6 digit ap/dn. count. 12.95

MK5002 4 dljlt counter 8.95

MK5021-C«I. chlpsq. root 2.50

* WW

Thermistors 1.5K ohm ....5/(1.00Tantalum Caps 1 mfd. 20VOC

P.C. Leads 15/(1.00

Flat Pack IC Assort 20/(1.00

Electrical Coil

13T Type C - 10T Type C 12/(1.00

2 Transistor Audio 8/(1.00

Trimmer Pots

10K, 20K, 25K, Mini 10/(1.00

Disc Caps For Bypass.01 mfg - 100 WUDC

PC Leads 40/(1.00

New Cambion JacksPart #450-4352

Z-80

Programming Manual

IN DEPTH DETAIL OF

THE 2-80 CPU

MICRO-COMPUTER

S. D. SALES SPECIAL

$9.95

Silicon Rectifier Special 1N4007. 4ft

1 amp 1000 PN 10/(1.00

Photocell Assortment ....12/(1.00Plastic Readout Filters

Amber 6/(1.00

Disc Cap Assortment 60/(1.00

P.C. Lead Diodes

1N4148 IN 914 100/(2.00

1N4002-1A-100 PN 40/(1.00

MICA Trimmer

PC402 Miniature

1.5-20 P.C. P.C. Mount. .4/(1.00Resistor Special 22 ohm

Carbon Comp 25/(1.00

Resistor Assortment 1/4 W 5% &

;. MICROPROCESSORCHIPS

8212-1/0 port 3.50

8214 —P.I.C 12.95

8216 — Non Invert Sua 4.95

8224 — Clock Gen 4.95

8226 —Invert Bus 3.95

PI0 for Z—80 14.95

CTC for Z—80 14.95

8228 Sys. Controller 8.20

8251 Prog. comm. Intarfact. .10.958255 prog. prap. interface.. .13.50

8820 Dual Line Recr 1.75

8830 Dual Lin* Dr 1.75

2513 Char. Gen 7.50

8838 Quad Bus. Recvr 2.00

74LS138N — 1/8 decoder 99

8T97Hax Trl-State Buffer ...1.25

1488/1489 RS232 1.50

TR 1602B Uart 3.95

TR 1863 Uart 8.50

FD 1771B-1 39.95

Gold Plated 50/(1.00^* 10% PC leads 200/(1.50^

CHOOSE (1. FREE MERCHANDISE FROM ASTERISK ITEMS ON EACH (15 ORDEFT

4001

19

4029

99

4002

19

4042

69

4011

19

4047

1.50

4013

32

4049

35

4016

32

4069

23

4017

95

4071

19

4020

97

4076

97

4022

97

14518

1.10

4024

75

14528

85

4027

39

14529

85

CALL IN YOUR BANKAMERICARD(VISA) OR MASTER CHARGE OR-DER IN ON OUR CONTINENTALTOLL FREE WATTS LINE:

1-800-527-3460

Texas Residents Call Collect:

214/271-0022

DEALER INQUIRIES INVITEDI

NO COD'S. TEXAS RESIDENTS ADD5% SALES TAX. ADD 5% OF ORDERFOR POSTAGE ft HANDLING . OR-DERS UNDER (10. ADD 75c HAND-LING.FOREIGN ORDERS - U. S.FUNDS ONLYI >

Circle 102 on inquiry card.

BYTE March 1978

223

Header Service

To get farther information on the products advertised in BYTE, fill out the readerservile card with your name and address. Then circle the appropriate numbers for theadvertisers you select from this list. Add a I3cenl stamp to the card, then drop it in themail. Not only do you gain information, but our advertisers are encouraged to use themarketplace provided by B YTf:. This helps tn. bring you a bigger BYTE.

Inquiry No.

Page No.

Inquiry No.

Page No.

1 AAA Chicago Computer Center 195

2 Alpha Digital 142

3 American Technologies 193

4 Anderson Jacobson 19

5 Apple Computer 16, 17, 119

6 Atwood Enterprises 197

136 AVR Electronics 193

7 Barnes Electronics 193

8 Benson & Costello 171

9 Berg Publications 172

10 BITS Inc, 125, 132, 146, 147, 150,211

11 Burroughs Inc 151

12 California Applied Technology 195

13 California Industrial 201

14 Canada Systems 167

15 Carterfone 93

16 Central Data 97

17 Centronics 49

18 Century Data Products 108

19 CMC Marketing 63

20 Component Sales 140

21 Comptronics 1'41

22 Computalker 75

137 Computer Components 202

23 Computer Corner 193

24 Computer Data Systems 103

25 Computer Depot 126

26 Computer Enterprises 102

27 Computer Hardware Store 195

33 Computerland 128, 129

28 Computer Mart of NH 195122 Computer Stop 195

30 Computer Systems Store 194

32 Computer Transceiver 133

34 Cromemco 1, 215 Dal Data Inc 93

35 Data Search 136

37 Digital Group 55 *

38 Digital Micro Systems 173

39 Digital Research 117

135 Digital Research Corp 203

40 Disc 3 194

41 Dynabyte 72, 73

42 Electrolabs 197

43 Electronic Control Tech 100

44 Electronic Systems 205

45 Electronic Warehouse 198

46 Charles Floto 193

48 Forethought Products 167140 Galileo 161

49 Gallagher Research Inc (GRI) 155

50 Hamamatsu Corp 21

51 DC Hayes 106

52 Heath 34, 57, CIV

53 Heuristics 51

54 Hobby World 207

* IEEE Computer Society 144, 145

55 IMSAI 91. Clll

56 Integral Data Systems 69

57 Integrated Circuits Unlimited 209

58 International Data Systems 137

60 James Electronics 212, 213

47 John Fluke Manufacturing 65

61 LE Labs 195

62 Lear Siegler 61

63 Logical Services 138

64 McGraw Hill Books 45

65 Meca123

66 Meshna215

* Micro Business 78 163

67 Micro-Corn 193

69 Micronics 108

70 Micropolis 110139 Micropolis 111

71 Microware 141

72 Midwestern Scientific Instruments 121

73 Mikos200

74 Mini Micro Mart 148, 217

75 Mountain Hardware 43

76 mpi 136

77 MSD 79

78 Multi Micro Media Corp 106

79 National Digital Diagnostic 195

80 National Multiplex 115

81 NCC78 135

82 Netronics 134

83 North Star Computer 23, 31

* Ohio Scientific 36, 37, 38, 39

84 OK Machine & Tool 70, 71

85 Oliver Advanced Engineering 54

86 Osborne & Associates 105

87 Owens Associates 193

88 Pacific Office Systems 202

89 PA IA Electronics 155

Inquiry No.

• Correspond directly with company.

Page No.

90 Parasitic Engineering 7

91 PerCom Data 131

92 Peripheral Vision 99

93 Personal Software 118

94 Pertec 26, 27

95 Phone I 139

* PolyMorphic Systems 25

96 Poly Paks 219

97 Priority I 221

98 Processor Technology 14, 15, 41

120 Professional Data 159

99 Rotundra Cybernetics 195

100 Scelbi 28, 29

101 Scelbi/BYTE Primer 157

* Scientific Research 47, 95

102 SD Sales 223

103 Michael Shrayer Software 109

104 Silver Spur 195

105 Ed Smith's Software 173

106 Smoke Signal Broadcasting 107

107 Software Exchange 159

108 Software Records 169

110 Solid State Sales 169

111 Solid State Time 170

112 Soroc 5

113 Southwest Technical Products CM

114 Space Byte 59

115 Space, the Final Frontier 93

116 Structured Systems Group 149

117 Summagraphics 130

118 Sybex199

119 Synchro Sound 101, 143

121 Tarbell 11

123 Technical Design Labs 87

124 Technical Systems Consultants 6719 TEI 63

125 Telecommunications Service 193

126 Texas Instruments 13

127 Trace Electronics 77

128 Vector Electronics 104

129 Vector Graphic 33

130 Vista Computers 112, 113

131 West Coast Computer Faire 165

132 Worldwide Electronics 194

133 Xitex100138 Xybek171

134 Yestronics 193

BDMB-

BV H'c (<n i i.ij Monitor' 6cx

Article No.

1

2

3

4

5

6

7

8

910111213

ARTICLE PAGE

Critchfield-Dwyer-Lederer: A Two Computer Music System 8

Helmers: An Apple to Byte 18

Raskin: The Microcomputer and the Pipe Organ 56

Kent: The Brains of Men and Machines: Part 3 74

Ciarcia: Program Your Next EROM in BASIC 84

Fylstra: User's Report: The PET 2001 114

Wilber: CIE Net: Part 2: Protocols 152

Jennings: Microchess 1.5 versus Dark Horse 166

Millan: Take a Course in Microprogramming 168

Olson: Controlling the Real World 174Hughes: Interfacing the Sykes OEM Floppy Disk Kit to a Computer 178

Holman: Get On at the Right Address 185

Castleman: The Intelligent Memory Block 186

Rampil Out-BOMBs Star TrekFor December

For the December 1977 BYTE, authorIra Rampil receives a BOMB bonus check of$100 for first place for "A Floppy DiskTutorial," page 24, and authors Kurt JSchmucker and Robert M Tarr receivea bonus of $50 for their second placearticle, "The Computers of Star Trek,"page 12. See page 27 for how BOMB cardratings are scored. Fill in the card oppositethis page; BYTE's editors read each one."

224

BYTE March 1978

$

The *6,000 DP

Center.

IMSAI Introducesthe VDP-80

Until now, owning real computing power meant payingunreal prices. Announcing the IMSAI VDP-80 Video DataProcessor, a complete computer, intelligent terminal andmegabyte floppy disk mass storage system. All in onecompact cabinet. All for just $5995? A complete desk topDP center.

For small business applications, the VDP-80 places astand-alone computer at your fingertips. And, our full lineof add-on peripherals, assures that the system can beexpanded as your needs do.

For the large business user, with an existing centralmainframe, the VDP-80 is the ultimate remote processor.You have the advantage of powerful local processingcapability, plus the epitome in cost-effectiveness forimplementing a distributed data communications network.

Take a close look at the following features. Then you'llknow why we call our VDP-80 the desk top DP center.

□ Powerful, High-Speed, Central Processor. 3 mHz

Intel 8085 microprocessor. 32K RAM memory (expandableto 196K). Parallel and serial I/O. Asynch, synch andbisynch communications. Programmable baud rates(.05-56 KB).

D Megabyte Mass Storage. PerSci dual floppy, doubledensity disk drive standard. One million byte storagecapacity. Three floppy disk drives can be added-on,providing 4 million bytes of on-line storage.

G Drives Printers, Plotters, Terminals, Modems andTape Drives. Supports up to six terminals or modems, andfour tape drives. Drives plotters, serial printers and lineprinters (up to 300 1pm).

Circle 55 on inquiry card.

D 12"CRT, 24x80 Field, User Programmable Font.

Character and line insert/delete allows fast programcorrection and text editing. Inverse video and programmablefield allows highlighting or enlarging graphics of informa-tion display. Titled fields protect information blocks frombeing written over accidentally. Programmable font (up to256 different characters) allows foreign language and specialpurpose character forms.

□ Alphanumeric Intelligent Keyboard. 62-pad mainkeyboard. Programmable 12-pad numeric keyboard. 12-padcontrol keyboard. Standard typewriter and calculatorkeyboard layouts. "N" key roll over reduces operator errorduring high-speed data entry.

D Commercial BASIC, FORTRAN IV, DOS Software.

Built-in ROM monitor allows extensive debugging anddiagnostics. BASIC, interactive or compiler version.FORTRAN IV level 2 ANSI compiler. DOS-enhanced CP/M .**

Distributed processing, financial reporting and analysis,word processing, whatever your application, the VDP-80 isyour answer.

Dial (415) 483-2093, and we'll tell you how you can putour $5995* DP Center on your desk top. When it comes tosmall business computers, Just Ask IMSAI.

•Base price VDP-80/1000. S5995. with 32K RAM memory and dual double density floppydisk drive. U.S. Domestic Price Onlv. Features and prices subject to change without notice."CP/M is a trademark of Digital Research Corporation.

The Standard of Excellencein Microcomputer Systems

IMSAI Manufacturing Corporation

14860 Wicks Blvd.

San Leandro.CA 94577

(415) 483-2093 TWX 910-366-7287

This 8-bit machine,

by itself, is as versatile

as a lot of systems

that include peripherals

Memory Display

Register Display

I/O Port Display

Be sure to use

:oupon on

page 34 of this magazine

to order your FREE

Heathkit Catalog!

why Ihe last bus

is the best bus

*■*■

=M;

cSzUSHi

«B*

"

FREE

&■*■

I'"7' —

Skeptical? For starters, because of itsunique designthe H8 is theonly machinein its priceclass thatoffers fullsystem inte-gration, yet,with just 4K ofmemory andusing onlyits "intelligent"

front panel for I/O, may be operatedcompletely without peripherals!

In addition, by using the features ofits built-in Pam-8 ROM panelcontrol program, the H8 actuallyallows you to dig in and examinemachine level circuitry.

Responding to simple instructionsthe "intelligent" panel displaysmemory and register contents, letsyou inspect and alter them evenduring operation. And for greaterunderstanding, the front panelpermits you to execute programs asingle instruction at a time. Theresult is a powerful, flexible learn-ing tool that actually lets you "see"and confirm each detail of H8'sinner workings.

If you need further evidence, consider the fact that H8's system

orientation allows you an almostunlimited opportunity for growth.

Memory is fully expandable, the8080A CPU extremely versatile,and with the addition of high speedserial and parallel interfacingyou gain the added flexibility ofI/O operation with tape, CRT con-soles, paper tape reader/punches,and soon floppy disk systems!

The H8 offers superior documen-tation including complete step-by-step assembly and operationmanuals, is backed by 54 years ofHeath reliability, and comescomplete with BASIC, assembler,editor, and debug software —others charge over $60 for!

H8, simplicity for thebeginner, sophisti-j^^^ cation for the expert

and at $375* just rightfor you.

Prices are mailorder net FOB,Benton Harbor,Michigan.Prices andspecificationssub)e.

change will:out notice.

System Engineeredfor Personal Computing

Circle 52 on inquiry card.