commodore 64 assembly language

276 Pages·2012·25.66 MB·English

COMMODORE
64
ASSEMBLY LANGUAGE
ARCADE GAME
PROGRAMMING
This book is dedicated to mypaients.
COMMODORE 64
ASSEMBLY LANGUAGE
ARCADE GAME
PROGRAMMING
STEVE BRESS
ITABITAB
BOOKS Inc.
Blue Ridge Summit, PA 17214
Game design by Dan and Steve Bress.
Illustrations by Elisa Frances Mosely.
Revenge of the Phoenix artwork by Denise McDonald.
PAC-Man is a trademark of Bally, Midway Mfg. Co.
DONKEY KONG is a trademark of Nintendo.
CENTIPEDE is a trademark of ATARI, Inc.
FIRST EDITION
FIRST PRINTING
Copyright © 1985 by TAB BOOKS Inc.
Printed in the United States of America
Reproduction or publication of the content in any manner, without express
permission of the publisher, is prohibited. No liability is assumed with respect to
the use of the information herein.
Library of Congress Cataloging in Publication Data
Bress, Steve.
Commodore 64 assembly language arcade game programming.
On t.p. the registered trademark symbol "TM" is
superscript following "64" in the title.
Includes index.
1. Commodore 64 (Computer)-Programming. 2. Assembler
language (Computer program language) I. Title.
QA76.8.C64B73 1985 001.64'2 85-2803
ISBN 0-8306-0919-9
ISBN 0-8306-1919-4 (pbk.)
Contents
Introduction viii
1-You and Your TV 1
How a Computer Displays a Picture
What Is Animation 2
2-A Language for Games 3
Assembly Language 4
Using an Assembler 4
What an Assembler Can Do for You 5
How to Choose an Assembler 6
3-Underlying Concepts 9
Bits and Bytes 9
The Hardware 10
6510 Architecture 11
4-The 6510 Assembly Language 13
Instruction Types 13
Addressing Modes 14
Immediate Mode Addressing-Zero Page Addressing-Zero Page Indexed Addressing-Absolute
Addressing-Absolute Indexed Addressing-Indirect Addressing with Indexes-Implied Addressing
Relative Addressing-Indirect Addressing
5-0rganizing Your Program 17
6-Working with Interrupts 19
7-Technical Information 21
Commodore 64 Address Space 21
Memory Control and Mapping 22
Graphics Memory Locations 28
Standard Text Mode 24
Color Memory 'Z1
Custom Character Sets 28
Multicolor Mode 28
Extended Background Color Mode 28
Bit Mapping 29
Multicolor Bitmapped Mode
Sprites 30
Sprite Pointers-Sprite Controls
Collision Detection 32
Blanking the Screen 33
The Raster Register 33
Video Interrupts 33
Scrolling 33
Joysticks 34
8-Sound Effects 36
Filtering 36
The Sound Generator Demo 41
The Sound Editor 41
9-Creating Graphics 47
Hand Coding Graphics 47
Using a Graphics Tablet 52
Using a Koalapad
Using the Sprite Maker 55
Using the Screen Maker Utility 56
10-Some Arcade Games 57
Pac-Man 57
Donkey-Kong 58
Centipede 58
Revenge of the Phoenix 59
Game Play-Scoring
11-Elements of Game Design 61
Visual Impact 62
Sound Effects 62
Difficulty Levels 62
Scoring 63
12-How Boghop Works 64
The Start of the Program 65
The Macro Library-RAM Definitions-Musical Definitions-The Data Section-The Point Plotting
Routine-The Equates Statements-Defining the System-Initializing RAM
The Main Program Loop 70
Scores-Moving the Bad Guys-Incrementing the Level of Play-Seeing if the Bad Guy Is Hit
Seeing if the Player Is Hit-Launching the Shots-Moving the Bad Guy's Shots-Moving the Player's
Shots-Checking the Shot Positions
Animating the Sprites 73
Displaying the Number of Lives-Resetting the Game-Maintaining the Timing
The Interrupt Routines 74
The Player Controls-Clear and Pull-INT1-Moving Mountains
The Movement Subroutines 76
An End Note 76
77
Appendix A-The Instruction Set
Appendix B-The Macro Library 99
Appendix C-The Program Listings 119
254
Glossary
257
Index
Introduction
This book, written for those who want a greater • A description of the code for a game program
understanding of their computer's operation, is
recommended for programmers who are familiar
with the essential concepts of machine language and After you have mastered some of the program
experienced in programming home computers in ming techniques, you will be shown how to take a
BASIC. It is also for machine language program game concept and turn it into a video game. Many
mers. Many of the examples given in the book are of the routines presented in this book were created
machine language subroutines that can be used by expressly for use in video game programming.
machine language programmers or called from However, in many cases techniques used in pro
BASIC to increase the speed of BASIC programs. gramming video games carry over into all other
This book is divided into three sections: fields of programming. By experimenting with the
new concepts and techniques as you read, you will
• Thchnical information find that you are increasing your understanding of
• Game and graphics design how to fully utilize your Commodore 64.
viii