Commodore PET User manual

PET-CBM

Personal

Co.puter

Guide

Carroll

Donahue

Janice

Enger

OSBORNE/McGraw-Hill

Berkeley, California

Published by

OSBORNE/McGraw-Hill

630

Bancroft

Way

Berkeley, Califomia

94710

For information on translations and book distributors outside

the

A. ,

please write OSBORNE/McGraw-HiII

the above address.

PET-CBM PERSONAL COMPUTER GUIDE

1234567890

0000

89876543210

ISBN

0-931988-30-6

1980

McGraw-HiII, Inc. Ali rights reserved. Printed in the United States

America. No

part

this publication may

reproduced, stored in aretrieval system, or transmitted in any form

by any means, electronic, mechanical, photocopying, recording

otherwise

without

the prior written

permission

the publishers.

Cartoons by Erfert Nielson.

The definitions on the back cover are adapted, with permission,

from

Webster's New World Oiction-

1980

by William Collins Publishers,

Inc.

The programs in this book were printed on aCommodore

CBM

Model

2022

Tractor Printer.

Table

Contents

Preface

1. Introducing the PET

Communicating

with

the

PET

ROM

and RAM

BASIC Programming

PET

Models

Features

2. Operating the PET

Unpacking

Cassette Hookup

Key

top Film Covering

Startup

Keyboard

Keyboard Entry

PET

Key Groups

Screen Display

Cassette Tape Drive

Cassette Operation

Cassette Tape Controls

Cleaning and Maintenance

Cleaning and Demagnetizing the Tape Head

Care

of Cassette Tapes

Elementary Troubleshooting

3. Programming the PET

Calculator

Immediate

Mode

AOne-Line Program 49

Reexecuting in Immediate

Mode

Modifying

aProgram

Elements 53

Numbers 53

Strings 57

Variables 58

Operators

Arrays 69

Functions

File Names 74

Writing

BASIC Programs 76

Line Numbers

BASIC Statement Groups 78

Developing aProgram 84

Modification

Example Tasks 107

4. PET BASIC 111

Format Conventions 112

BASIC Commands 112

CLR

112

NT 112

LIST 113

LOAD 114

NEW 117

RUN

117

SAVE 119

VERIFY

120

BASIC Statements 123

123

CMD 124

DATA

125

DIM 126

END 127

FOR .NEXT [STEP] 127

GET

129

GET*

130

GOSUB

131

GOTO

131

IF.

.THEN

131

INPUT 133

INPUT*

134

LET =135

ON. . GOSUB 136

ON.

.GOTO 136

OPEN

137

POKE

143

PRINT 143

PRINT*

145

REM

147

RESTORE

148

4. (Contlnued)

RETURN

STOP

WAIT

BASIC

Arithmetic

Functions

ABS

ATN

COS

EXP

INT

LOG

RND

SGN

SIN

SOR

TAN

BASIC

String

Functions

ASC

CHR$

LEFT$

LEN

MID$

RIGHT$

STR$

VAL

BASIC Format

Functions

POS

SPC

TAB

BASIC System

Functions

FRE

PEEK

SYS

TI.

TI$

USR

User-Defined

Function

DEF

Making

the

Most

of PET Features

Keyboard Rollover

Buffer

Two-Key

Repetition

Strings

Concatenating

Strings

Numeric

Strings

Programmed Cursor

Movement

The PRINT

Statement

The CHR$

Function

Arithmetic

Addition

Subtraction

Multiplication

148

149

150

151

152

153

154

155

156

157

158

159

160

161

162

163

164

167

174

177

180

182

185

188

189

190

202

215

vii

5. (Continued)

Graphies

Graphies in Calculator Mode

Programming Graphies

Summary

Animation

Time Delay

Programming Character Placement

Summary

Files

Program Files

Data Files

File Handling

Writing

aData File

Reading aData File

Alternate Character Set

Features of the Alternate Character Set

BASIC

Word

Abbreviations

Setting the Clock

Digital Display Clock

POKE

the Screen

Calculating the Screen Address

Generating Random Numbers

6. System Information

Organization of the

PET

System

Memory

Map

PET

BASIC Interpreter

BASIC Statement Storage

User Program Area Initialization

Data Formats

Array Header

Assembly Language Programming

Appendices

PET

ASCII Codes

PET

Error Messages

Operating System Error Messages

Program Examples Solved

BASIC Bibliography

PET

Newsletters and References

Conversion Tables

Hexadecimal-Decimal Integer Conversion

Powers of

Two

Mathematical Constants

Powers

Sixteen

Powers

Variations for Original ROMs (Revision Level

PET

Features

Index

viii

225

229

231

232

233

237

239

240

242

255

273

277

278

281

285

288

291

303

308

310

312

315

317

322

329

347

361

366

369

387

389

393

394

400

401

403

425

427

FIGURES

1-1

Three Models of the Commodore

PET

2-la

Front

View

of Compact Keyboard

PET

2-lb

Front View of Full Size Keyboard

PET

2-2 Back

View

PET

2-3 Full Size

PET

Keyboard 12

2-4 Compact

PET

Keyboard 13

2-5 The

PET

Video Screen 32

2-6 The

8x8

Dot

Matrix

2-7

PET

Cassette Tape Drive 34

2-8 Inserting aTape Cassette 35

2-9

PET

Cassette Tape Head 39

2-10 ATypical Tape Head Demagnetizer

2-11

Write

Protect Notches

2-12

PET

Internai

View

2-13

Memory

Deviee Unconnected

2-14 Extractor Tooi

2-15 RAM Numbering

4-1

Logical Files 139

5-1

Odd/Even Division of

PET

Keyboard 170

5-2 Odd/Even Three-key Rollover

171

5-3 Draw the Square

228

5-4 Make Program Statement from Graphies

230

5-5 Using PRINT:#:

244

5-6 MAIL. PRINT:#: 252

5-7

Read

aData File 256

5-8 MAIL. INPUT:#:

264

5-9 Format Printing Using

GET:#:

272

5-10

Standard/

Alternate Character Set Decision 274

5-11 Standard to Alternate Character Set

276

6-1

PET

Block Diagram

304

6-2 Principal Pointers in User Program Area

311

6-3 BASIC Statement Storage 312

6-4 User Program Area on Power-up

316

TABLES

2-1

Special Symbols

Program Operators 19

2-2 Graphie Character

Keys

3-1

Special String Symbols 58

3-2 Reserved Words 62

3-3 Boolean Truth Table 67

3-4 Operators 69

4-1

Physical Deviee Numbers 140

4-2 Secondary Address Codes

141

4-3

Values for Tape 1/0 162

5-1

Addition

Operations

181

5-2 Keyword Abbreviations 280

6-1

PET

Memory Allocation by

Blocks 304

6-2

PET

Memory Map

(Rev.

ROMs)

334

6-3

PET

BASIC Keyword Codes 313

6-4

ASCII Standard 7-Bit Codes 327

6-5

PET

Screen Memory 7-Bit Codes 328

G-l

PET

Memory Map

(Rev.

ROMs)

41L1

Preface

The personal computer field was already brimming

with

excitement when

the Commodore

PET@

entered the scene in late 1977. A

minimum

PET

system,

housed in aself-contained

unit

with

custom keyboard, video display, and tape

cassette, cost

just

$595.

The

PET

was an immediate sales success.

Many

thousands of units have

been sold, and

PET

user groups are springing up ail over.

The

PET

has surely become famous

one of the first popular personal com-

puters.

has also become

widely

known -indeed infamous

-as

having the

most meager literature auser

has

ever had to face.

That

why

this book

has

been

written.

After

reading this book vou

will

have agood understanding of

what

aper-

sonal computer -especially the

PET

-can

expected to

for vou. Certainly

important

knowing

what

vou can do

with

apersonal computer

knowing

what

vou

can't

do.

Sy examining the capabilities and limitations of the

PET.

vou

will

have agrasp of

what

vou can realistically expect apersonal computer

for

Vou

which

important ifvou have apersonal computer, or

Vou

are thinking

of getting one.

There are numerous programming examples throughout this book; by

reproducing these examples vou

will

quickly get your

PET

working. These exam-

pies are thoroughly described and documented so vou can leam

how

and

why

the

This manual suits for next models

Table of contents

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