S-100 Bus Handbook by Dave Bursky

THE S-100 BUS HANDBOOK THE S-100 BUS HANDBOOK DAVE BURSKY 11 HAYDEN BOOK COMPANY, INC. Rochelle Park, New Jersey Dedication I would like to thank the many friends that helped me to complete this book. Many thanks to Jeff Bierman and Robert Meehan for some of the photographs, and to Katherine Berger, Clare Bursky, and Hilary Mendelson for their typing and proofreading. I am also grateful for the encouragement of others too numerous to name. Additionally, I would like to thank the many manufacturers that loaned various pieces of S-100 bus equipment to me for use in preparing the book. Some of the many companies include: AP Products, Advanced Micro Devices, Ball Brothers Research, Circuit Stik (now part of Bishop Graphics), Continental Specialties, E & L Instruments, EMM Semiconductor, Extensys Corp., Intel Corp., MITS (now part of Pertec Computer Corp.), Motorola, National Semiconductor, NEC Micro- computers, Oliver Audio Engineering, Seals Electronics, Shugart, Solid-State Music (now called SSM), Southwest Technical Products, Technical Design Labs (now called Xitan Corp.), Texas Instruments, Triple I Corp., Vector Electronics, and Vector Graphic Corp. Library of Congress Cataloging in Publication Data Bursky, Dave. The S- 100 bus handbook. Includes index. 1. Microcomputers . 2. Microcomputers-Buses. 1. Title. TK7888.3.B84 621.3819 '58'3 79-26153 ISBN 0-8104-0897-X Copyright © 1980 by HAYDEN BOOK COMPANY, INC. All rights reserved. No part of this book may be reprinted, or reproduced, or utilized in any form or by any electronic, mechanical, or other means, now known or hereafter invented, including photocopying and recording, or in any information storage and retrieval system, without permission in writing from the Publisher. Printed in the United States of America 1 2 3 4 5 6 7 8 9 PRINTING 80 81 82 83 84 85 86 87 88 YEAR Preface The material in this book has been put together from the many operating manuals and system descriptions published by the various manufacturers mentioned in this book. And, in many cases, the complete latest schematic revision of the par- ticular board described has been included for handy reference. In total, this book is intended to serve as a quick, handy compendium of technical information about S-100 bus equipment. And, although some companies have changed names, been acquired by others, or closed their doors, many thousands of their boards are in the field, and this book will be one of the few places that data will be available. The boards covered in this book span a wide range of functions, and although it would be impossible to cover every manufacturer's product in a single book, the equipment described here is representative of the many other products that are available. Companies such as MITS and IMSAI were the pioneers in the field of "per- sonal" computing, which has now opened up to an extremely large assortment of low-cost completely assembled systems, some using the S-100 bus and others using proprietary bus structures. However, another controversy covered in this book is that of just what is the S-100 bus. MITS introduced the original version of it on their Altair 8800 microcomputer system, revised it for the 8800b system and then developed an entirely new structure. The pin definitions picked by Imsai were very similar to those of MITS, but there were some differences-differences that make some of the boards that operate in one system incompatible on the other system. For future S-100 bus systems, many of the incompatibility problems should be eliminated as the "standard" for S-100 bus systems that has been developed by a committee of IEEE (Institute of Electrical and Electronic Engineers) becomes widely adopted. Included in Ap- pendix D is a summary of the new standard, including a listing of all the pins and their definitions. Not only will this book serve as a handy compendium of information about the boards, but it will serve as a simple guide to troubleshooting some of the basic simple system failures beyond "it doesn't work." Detailed troubleshooting information would require a book on each type of board, so the material included here will just help track down the problem to a defective board, system component, or program. I would just like to add a word of thanks to all the microcomputer manufacturers that helped me put this material together and hope that for you, the user, it serves its intended purpose. DAVE BURSKY Contents 1. Basic Introduction to Computers and Microprocessors A Little Computer Prehistory 1 What Is a Computer? 4 What Is a Microprocessor? 6 The Microprocessor Operates in Cycles 9 2. Binary Mathematics and Boolean Algebra 11 Computer Math: A Quick Review 11 Nondecimal Numbering Systems 12 Doing Math with Binary Numbers 13 Using Logic Operators 14 Combining Logic Operators 15 The Basic Rules of Boolean Algebra 16 3. Introductory Electronics and Logic Functions 17 Let's Look at the Components 18 The Basics of Solid-State Technology 19 Transistors: Semiconductor Control Elements 20 The Integrated Circuit 23 More Complex Circuits 23 Cascaded Flip-Flops Count 27 4. The Basic S-100 Bus and the Computer Mainframe 33 Control and Signal Lines Hold the System Together 37 The CPU Works like This ... 38 5. Computer Memory Systems 40 The Random-Access Memory: What Is It? 40 Start with the Static Memories 42 ROMs: ICs That Remember 45 The PROMs Are Programmed like This ... 49 Design the Board That Remembers 50 6. Input/ Output Interfaces for the S-100 Bus 54 Study the 8251 Before Using Board 57 Get the Board Up and Running 58 Another Path to the Same End 61 Status Information Is Important Too 63 Don't Want Serial? Go Parallel 64 Combine Functions onto a Single Board 68 Other Designs Provide Different Performance 69 7. Peripheral Storage Devices for Microcomputer Systems 71 Storing Your Programs-Which Way to Go? 71 Boost Data Entry and Storage Speed with Cassettes 73 Using the Cassette Interface 75 Control the Recorder with the Computer 78 Consider the Kansas City Standard 79 Get Larger Storage Capability with a Floppy 86 Printer Control Signals Are Important 89 8. Programming the 8080 CPU in the S-100 Bus Microcomputer 91 Start by Flowcharting the Problem 92 Get to Know the 8080A Programming Model 93 Condition Bits in the 8080A Tell You Its Secrets 95 Examine the 8080A Instruction Set Carefully 95 Write Your Programs Systematically 102 Organize Your Work Carefully When Writing Programs 105 Use Software from Others to Write Your Own 107 Pseudo Operations Add Flexibility to the Assembler 109 Now That You Have BASIC, What Do You Do With It? 121 9. Interfacing the Microcomputer to Real-World Applications 122 Bring Analog Signals into the Digital World 122 Provide Control for Large Loads 127 Get to Know the 88-PCI Board Options 130 10. Troubleshooting the Microcomputer System 139 Decide on the Level of Repair You'll Handle 139 Check the Memory with Software 140 Software Bugs: Gremlins That Can Drive You Crazy 144 APPENDIX A. Reference Books and Publications 149 Basic Electronics and Integrated Circuits 149 Programming 149 Microprocessors 150 Advanced Digital Theory and Computer Architecture 150 Troubleshooting 150 Publications 150 APPENDIX B. Commonly Used Components and Suppliers of S-100 Bus Systems 152 Low-Power Schottky TTL 152 4000 Series CMOS 153 Microprocessor Manufacturers 154 S-100 Computer and Board Manufacturers 156 Printers 157 CRT Terminals 157 Printing Terminals 157 Breadboarding and Cabinets 157 PROM Erasers 157 Floppy Disk Drive and Controller Manufacturers 157 Supplementary Products 158 Component and Surplus Dealers 158 APPENDIX C. Schematic Diagrams of Commonly Used S-100 Bus Boards 160 Contents 160 APPENDIX D. Proposed S-100 Bus Standard 249 INDEX 255 CHAPTER 1 Basic Introduction to Computers and Microprocessors So you want to use a computer. But just buying one Early Western civilization, though, struggled along and reading the instruction and operating manuals will without such a handy device. Moreover, it had to make not get you very far, especially if you're not familiar with do with the numbering system devised by the Romans- programming or electronics. what today we call Roman numerals: By itself, a computer is nothing more than a collec- I=1, V=5, X= 10, tion of electronic circuits arranged to process information that is fed into it. In addition to all the electronics, C = 100, and M = 1000 therefore, a computer requires some sort of language to communicate back and forth with the operator-you. It wasn't until the thirteenth and fourteenth centuries Such a language consists of a stable of commands that that the decimal system of Arabic numerals we use can be combined in various ways to make the computer today-0, 1, 2, 3, 4, 5, 6, 7, 8, and 9-came into wide- do almost anything-solve business problems, simulate spread use. Except for the zero, the numbering system speech, play music, play games, or even solve mathe- dates back to about the fifth century. However, the idea matical equations. of a placeholder, the zero, was not developed until about the ninth or tenth century. Today, the decimal numbering system is used A Little Computer Prehistory throughout the world as a common mathematical tool. Ever since man started counting on his hands and However, most computers don't operate with decimal toes, he has been trying to find easier and faster ways numbers-they use one of the forms of binary number to do everything. The Chinese abacus, developed before representations to perform their operations. We'll talk 2000 B.C., was one of the first calculating machines more about numbering systems and how they work in (Fig.

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