Inside the Apple IIc

384 Pages·2011·28.84 MB·English

by  Gary B. Little

Inside the
Apple 1/c
Gary B. Little
Brady Communications Company, Inc.
A Simon & Schuster Publishing Company _
New York, NY 10020
Inside the Apple lie.
Copyright© 1985 by Brady Communications Company, Inc.
All rights reserved. No part of this publication may be reproduced or transmitted in
any form or by any means, electroniC or mechanical, inch.).ding photocopying and
recording, or by any information storage and retrieval system, without permission in
writing from the publisher. For information, address Brady Communications Com
pany, Inc., A Simon & Schuster Publishing Company, 1230 Avenue of the Americas,
New York, NY 10020.
Library of Congress Cataloging in Publication Data
Little, Gary B., 1954-
Inside the Apple lie.
On t.p.IIc appears as //c.
Includes bibliographies and index.
1. Apple lie (Computer) I. Title: Inside the Apple
2c. II. Title: Inside the Apple two c. III. Title.
QA76.8.A66225L57 1985 001.64 84~27419
ISBN 0-89303-564-5
Printed ii1 the United States of America
85 86 87 88 89 90 91 92 93 94 95 2 3 4 5 6 7 8 9 10
Production Editor/Text Designer: Michael J. Rogers
Art Director: Don Sellers
Assistant Art Director: Bernard Vervin
Cover Photography: George Dodson
Manufacturing Director: John A. Komsa
Copy Editor: Rita Progler
Typesetting: Automated Graphic Systems, White Plains, MD
Printing: R. R. Donnelley & Sons Co., Harrisonburg, VA
Typefaces: Helvetica (display), Aster (text), and Universal Mono type #3 H-P (computer programs)
To my wife, Pamela
Limits of Liability and Disclaimer of Warranty
The author and publisher of this book have used their best efforts in pre
paring this book and the programs contained in it. These efforts include the
development, research, and testing of the theories and programs to determine
their effectiveness. The author and publisher make no warranty of any kind,
expressed or implied, with regard to these programs or the documentation
contained in this book. The author and publisher shall not be liable in any
event for incidental or consequential damages in connection with, or arising
out of, the furnishing, performance, or use of these programs.
Note to Authors
Have you written a book related to personal computers? Do you have an
idea for developing such a project? If so, we would like to hear from you.
Brady produces a complete range of books for the personal computer market.
We invite you to write to Editorial Dept., Brady Communications Co., A Simon
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Trademarks of Material Mentioned in This Text
Apple //e, Applesoft, Apple II, Apple II Plus, Apple 1/c, Apple I, Integer BASIC,
DOS 3.3, Lisa, Macintosh, and ProDOS are trademarks of Apple Computer,
Inc.
Contents
Preface I xlll
1 An Introduction to Apple and the Apple //c I 1
A Condensed History of Apple Computer, Inc. I 1
Hardware and the Apple 1/c I 7
Learning the Fundamentals I 8
What Won't Be Covered I 9
Using the Optional Diskette I 9
Further Reading for Chapter 1 I 18
2 The 65C82 Microprocessor I 11
Important 65C02 Concepts I 12
Zero Page and the Stack I 12
65C02 Instruction Set I 13
65C02 Registers I 21
The Accumulator-A I 21
The Index Registers-X andY I 22
The Processor Status Register-P I 23
Carry Flag (C) I 23
Zero Flag (Z) I 24
Interrupt Disable Flag (I) I 24
Decimal Mode Flag (D) I 25
Break Flag (B) I 25
Overflow Flag (V) I 25
Negative Flag (N) I 26
The Stack Pointer-S I 26
The Program Counter-PC I 27
65C02 Addressing Modes I 27
Immediate I 28
Absolute I 29
Accumulator I 38
Implied I 38
Zero-Page Indexed Indirect I 38
Zero-Page Indirect I 31
Indirect Indexed I 31
Absolute Indexed I 32
Relative I 32
Absolute Indirect I 33
Absolute Indexed Indirect I 33
65C02 Input/Output Handling I 33
65C02 Interrupts I 34
Reset Interrupt I 36
v
c=J
vi lnsidetheApple//c ----------------
Interrupt Request (IRQ) I 36
The BRK Instruction I 37
The 65C02 Memory Space on the llc I 38
RAM Memory I 38
Input/Output (IIO) Memory I 41
ROM Memory I 42
Further Reading for Chapter 2 I 42
3 The System Monitor I 45
The System Monitor Commands I 46
The DISPLAY Command : Displaying the Contents of Memory I 46
The STORE Command : Changing the Contents of M;emory I 49
The MOVE Command: Copying the Contents of Memory I 51
The VERIFY Command : Comparing Ranges of Memory I 53
The EXAMINE Command : Examining the 65C02 's Registers I 53
The GO Command : Running a Program I 54
The LIST Command: Disassembling Assembly-Language
Programs I 55
The NORMAL and INVERSE Commands: Changing Video Display
Modes I 57
The ADD and SUBTRACT Commands: Simple Arithmetic I 57
The BASIC and CONTINUE BASIC Commands : Entering
Applesoft I 57
The USER Command: User-Defined Command I 58
The KEYBOARD and PRINTER Commands : Redirecting Input and
Output I 59
Multiple Commands on One Line I 61
System Monitor Subroutines I 61
Further Reading for Chapter 3 I 65
4 Applesoft BASIC I 67
Applesoft Memory Map I 68
Tokenization of Applesoft Programs I 73
Keyword Tokens I 74
Storage of Applesoft Variables I 77
Storage of Simple Variables I 78
The Name Header I 79
The Data Field I 80
End of Simple Variables I 82
Storage of Array Variables I 83
The Name Header I 83
Dimensioning Bytes I 83
The Data Field I 85
End of Array Variables I 85
Representation of Integer Numbers I 85
Representation of Real Numbers I 87
c:=J
----------------------.., Contents vii
Number Theory I 87
Binary Floating-Point Format I 87
How an Applesoft Program Runs I 89
'The CHARGET Subroutine I 91
Changing Program Flow I 93
Finding Line Numbers I 93
Linking Applesoft to Assembly-Language Programs I ,94
The CALL Command I 95
The & Command / 95
The USR Function I 96
Applesoft's Built-In Subroutines I 97
Using Applesoft's Built-ln Subroutines I 104
Locating Variables I 104
Evaluating Formulas I 108
Converting Numbers I 108
Further Reading for Chapter 4 I 112
5 The ProDOS Disk Operating System I 115
Formatting Diskettes I 116
ProDOS Memory Map I 116
:ProDOS Page 3 Vectors I 118
Filenames and Pathnames I 118
BASIC.SYSTEM Commands I 121
File Management Commands I 122
File Loading and Execution Commands I 123
File Input/Output Commands I 124
Miscellaneous Commands I 125
ProDOS File Storage I 126
Volume Bit Map I 126
Diskette Directory I 127
"Protecting" Files I 130
Storing File Data I 131
MLI-Accessing the Diskette Directly I 132
READ.BLOCK Program I 134
Further Reading for Chapter 5 I 140
6 Character Input and the Keyboard I 141
Standard Character Input Subroutines I 145
Reading One Character I 146
RDKEY ($FD0C) I 146
Keyboard Input I 148
Escape Sequences I 148
RDCHAR ($FD35) and ESCRDKEY ($CCED) I 150
Readiu'g a· Line of Characters I 150
Changing Input Devices :The Input Link I 152
How About Output? I 153
viii [=:J Inside the Apple //c ---------------
Designing a KSW Input Subroutine I 153
Replacing the Keyboard Input Subroutine I 153
ProDOS and the Input Link I 154
The Keyboard I 157
Encoding of Keyboard Characters I 157
Special Keys I 159
The "Apple" Keys I 159
Keyboard 110 Locations I 168
Modifying the Keyboard Input Subroutine I 164
Keyboard Auto-Repeat I 168
Resetting the Apple llc I 173
Special RESET Procedure I 173
Trapping "Soft" RESETs I 174
Trapping RESET from Assembly Language I 175
Trapping RESET from Applesoft I 176
Further Reading for Chapter 6 I 181
7 Character and Graphic Output and VIdeo Display Modes I 183
Text Mode I 184
The 80140 Switch I 185
Turning on the Text Display I 185
Text Mode Memory Mapping I 188
40-Column Text Mode I 189
80-Column Text Mode I 191
Using Page2 of Text I 192
Video Display Attributes: Normal, Inverse, Flash I 194
MouseText I 196
Standard Character Output Subroutines I 199
Video Output I 288
Video Screen Windowing I 282
How COUTl and C3COUT1 Set the Video Attribute I 283
Changing Output Devices : The OUTPUT Link I 285
Designing a CSW Output Subroutine I 206
Replacing the Video Output Subroutine I 206
ProDOS and the Output Link I 286
Low-Resolution Graphics Mode I 287
Turning on the Low-Resolution Graphics Display I 208
Low-Resolution Graphics Screen Memory Mapping I 209
Low-Resolution Graphics Colors I 209
Double-Width Low-Resolution Graphics I 210
Turning on Double-Width Low-Resolution Graphics I 210
Double~ Width Low-Resolution Graphics Screen Memory
Mapping I 212
Double-Width Low-Resolution Graphics Colors I 212
Built-In Support for Low-Resolution Graphics I 213 '
High-Resolution Graphics Mode I 214
c::=J
--------------------- Contents ix
Turning on the High-Resolution Graphics Display I 215
High-Resolution Graphics Screen Memory Mapping I 217
High-Resolution Graphics Colors I 219
Animation with High-Resolution Graphics I 220
Double-Width High-Resolution Graphics I 221
Turning on Double-Width High-Resolution Graphics I 222
Double-Width High-Resolution Graphics Screen Memory
Mapping I 222
Double-Width High-Resolution Graphics Colors I 223
Built-In Support for High-Resolution Graphics I 223
Further Reading for Chapter 7 I 225
8 Memory Management I 229
16K Bank-Switched RAM Areas I 230
Using Bank-Switched RAM I 231
Reading the Status of Bank-Switched RAM Soft Switches I 232
Auxiliary Bank-Switched RAM I 234
Playing with Bank-Switched RAM I 235
Bank-Switched RAM and ProDOS I 236
Auxiliary RAM Memory Area I 236
Using Auxiliary Memory I 237
The ALTZP Switch I 237
The RAMRD and RAMWRT Switches I 239
Auxiliary Memory Support Subroutines I 241
AUXMOVE ($C311)-Transferring data to and from auxiliary
memory I 241
XFER ($C314)-Transferring control to a program from main or
auxiliary memory I 244
Running Co-Resident Programs I 245
Initialization of the Auxiliary Stack I 251
Using CONCURRENT I 251
Limitations of CONCURRENT I 252
Further Reading for Chapter 8 I 253
9 The Speaker I 255
Generating Musical Notes I 255
Generating Music I 259
Further Reading for Chapter 9 I 263
10 Mouse and Game Controller Input I 265
The Apple Mouse I 265
How the Mouse Works I 266
Mouse Operating Modes I 267
Passive (Transparent) Mode I 267
Movement Interrupt Mode I 268
Button Interrupt Mode I 268