Osborne/McGraw-Hill THE OSBORNE/McGRAW-HILL Thom Hogan The Osborne/McGraw-Hill CP/M User G uide Third Edition by Thom Hogan Osborne/ McGraw-Hill Berkeley, California Published by Osborne/ McGraw-Hill 2600 Tenth Street Berkeley, California 94710 U.S.A. For information on translations and book distributors outside of the U.S.A., please write to Osborne/McGraw-Hill at the above address. THE OSBORNE/McGRAW-HILL CP/M® USER GUIDE Copyright® 1981, 1982, 1984 by M cG raw -H ill, Inc. All rights reserved. Printed in the United States of America. Except as permitted under the Copyright Act of 1976, no part of this publication may be reproduced or distributed in any form or by any means, or stored in a data base or retrieval system, without the prior written permission of the publisher, with the exception that the program listings may be entered, stored, and executed in a computer system, but they may not be reproduced for publication. 1234567890 DODO 8987654 ISBN 0-88134-128-2 Karen Hanson, Acquisitions Editor Ralph Baumgartner, Technical Editor Ellen Guethlein Silge, Copy Editor KLT van Genderen, Text Design Yashi Okita, Cover Design Photography by Richard Cash and Harvey Schwartz An earlier version of this book was reviewed for technical content by William Fairman of Faircom and Doug Huskey of Digital Research. Technical editors were Curtis A. Ingraham and Martin McNiff. Compositional editor was Denise E.M. Penrose. Hogan, Thom , 1952- The CP/ M User Guide: For all CP/ M-80 and CP/ M-PLUS Users Bibliography: p 267 Includes index. 1. CP/M (Computer program) 2. Operating Systems (Computers) I. Title. II. Title: CP/M user guide CP/M , CP/M-80, CP/M-86, and CBASIC are registered trademarks of Digital Research. CP/M-PLUS, MP/M, MP/M-86, SID, CB-80, MAC, PL/1-80, PL/1, and Pascal/MT+ are trademarks of Digital Research. The Osborne/McGraw-Hill CP/M® User Guide is not sponsored or approved by or connected with Digital Research. All references to CP/M, CP/M-80, CP/M-86, CP/M-PLUS, MP/M, MP/M-86, SID, CB-80, MAC, PL/1-80, PL/1, Pascal/MT+, and CBASIC in the text of this book are to the trademarks and registered trademarks of Digital Research. The italicized names are trademarks of the following companies (with registered trademarks denoted by ®): Apple® and Apple® II are registered trademarks of Apple Computer, Inc. d B A S E II® is a registered trademark of Ashton-Tate. ATARI® is a registered trademark of Atari, Inc. UNIX is a trademark of AT & T. Commodore® is a registered trademark of Commodore Business Machines, Inc. Condor is a trademark of Condor Computers, Inc. Cromemco® is a registered trademark of Cromemco, Inc. Nevada COBOL and Nevada FORTRAN are trademarks of Ellis Computing. FORTH® is a registered trademark of FORTH, Inc. IBM®, IBM® 3740, and IBM® PC DOS are registered trademarks of International Business Machines Corporation. Pascal/2 is a trademark of Ithaca Intersystems, Inc. WordStar® is a registered trademark of MicroPro International Corporation. Microsoft® BASIC is a registered trademark of Microsoft Corporation. North Star is a trademark of North Star Computer, Inc. Onyx is a trademark of Onyx Systems, Inc. Osborne® is a registered trademark of the Osborne Computer Corporation. Peach Text and Magic Wand are trademarks of Peachtree Software, Inc. P M AT E is a tradem ark of Phoenix Software. Radio Shack is a trademark of Radio Shack/Tandy Corporation. SuperCalc® is a registered trademark of Sorcim Corporation. Texas Instruments® is a registered trademark of Texas Instruments, Inc. Vector Graphic® is a registered trademark of Vector Graphic, Inc. VisiCalc® is a registered trademark of VisiCorp. Z80® is a registered trademark of Zilog, Inc. This book is dedicated to Lore Harp, Carole Ely, Steve Jobs, Steven Wozniak, Gary Kildall, and Seymour Rubenstein, who gave me the tools to write it. Contents Introduction vii 1 Computers, CP/M , and Operating Systems I 2 The Development of CP/M 15 3 Using C P /M 25 4 CP/M ’s Built-In Commands 39 5 Basic CP/M Transient Commands 65 6 Additional CP/M-PLUS Transient Commands 107 7 Other Transient Programs in CP/M 125 8 CP/M-80 Assembly Language Utilities 153 9 CP/M-PLUS Assembly Language Utilities 173 10 The Technical Aspects of CP/M 199 11 Assembly Language Programming With CP/M 241 12 MP/M, CP/NET, and CP/M Derivatives 255 A ASCII Character Codes 273 B Disk Selections 277 C Differences in CP / M Versions 281 D File Types Commonly Used in CP/M 285 CP/M Prompts 287 Error Messages 289 Sources of Information 311 Glossary 315 Index 323 Introduction Your computer is not a single unit but an interrelated system of devices and programs. You must direct these components to carry out any program you wish to run. CP/M-80 and CP/M-PLUS are operating systems that do much of this Job for you. They direct the activities of your computer’s components and manage files that contain computer instructions or data. Although CP/M-80 and CP/ M-PLUS are complex computer programs, you can learn to use them even if you do not have any prior computer experience. This book introduces the novice computer user to the microcomputer system and examines CP/ M’s function within that system. Chapters 1 and 2 provide the basic, practical information you need to get started, and they present a history of CP/M ’s development. Chapter 3 rounds out the fundamentals you need to know to use CP/M. Chapters 4 through 6 detail the CP/M-80 and CP/M-PLUS commands. Chapter 7 describes how other programs you purchase (or create) relate to CP/M; you’ll be introduced to the concept of computer languages and application programs in this section. This is information you will use every day, so we recommend that you study the examples carefully. The beginning seven chapters of this book provide a solid foundation for understanding what CP/M is and how to use it. Beginning with Chapter 8, the book goes beyond the functions normally needed by business or casual computer users and starts a discussion of emphasis on how these relate to assembly language programming. Chapter 11 combines the information presented in the previous three chapters to provide a step-by-step example of how to program in assembly language using CP/M . The last chapter, Chapter 12, discusses C P/M ’s relatives: how they differ, what they do, and why you might be interested in them. An annotated bibliography provides directions for additional reading, and several other appendixes offer practical con­ sumer information about CP/M-compatible programs, languages, and products. Some special introductory comments regarding this revised edition of the Osborne/ McGraw-Hill CP/ M® User Guide are in order. The primary concerns in rewriting, restructuring, and adding to the text for this third edition were to make the book more up-to-date and to include CP/' M’s latest generation, CP/M-PLUS. As happens with many works, the author had second (and third) thoughts about how to make some sections clearer. The CP/ M-PLUS com­ mands and information have been integrated into the text in a manner that allows owners of either CP/M-80 or CP/M-PLUS to make equal use of this book. For readers interested in learning about 16-bit versions of CP/ M, Osborne/ McGraw-Hill publishes a user’s guide specifically for those operating systems. Much effort has been expended to make this revision the most complete and accurate manual for 8-bit CP/ M users. If you have a working computer system, read this book while seated in front of your computer. Try the commands and examples presented here; do not Just read about them. You will be comfortable with CP/M much sooner than you expected. One last comment: The terms CP/M , CP/M-80, and CP/M-PLUS are used in this book with specific meanings. Whenever we refer to CP/ M, we are writing about all versions of CP/ M. However, whenever we refer to CP/ M-80 or CP/ M-PLUS, we are referring to specific (and different) versions of the operating system. Books, like computer programs, are never completely error-free. The author and publisher invite your comments and criticisms. This book is the work of the author and the publisher; it has not been reviewed, authorized, or endorsed by Digital Research. th Palo Alto 1984 CHAPTER A Computers, CP/M, and I Operating Systems This chapter presents the basic information that allows you to understand what an operating system like C P / M is, why it is necessary, and how it relates to the specific parts of the computer. You’ll also learn a few computer terms and information about the diskettes used by CP/M. CP/M is a disk operating system for microcomputers produced by a company named Digital Research. When CP/ M was first introduced, its creator indicated that the initials stood for “Control Program/Monitor.” Since then, however, it has become more popular to refer to it as “Control Program for Microcomputers.” Versions of CP/M are available for a wide variety of microcomputers from a number of different sources, and the introduction of new versions of CP/ M can be expected when new central processors are invented. CP/ M-80 and CP/ M-PLUS can be used on almost any microcomputer that uses the 8080, 8085, or Z80 central processor unit and has 8-inch or 5 1 / 4-inch floppy disk drives.