Commodore Amiga Quick user guide

Hardware
Reference Manual
Commodore Business Machines, Inc.

Amiga Hardware Reference Manual
Commodore Business Machines, Inc.
Amiga Technical Reference Series
•
••
Addison-Wesley Publishing Company, Inc.
Reading, Massachusetts Menlo Park, California Don Mills, Ontario
Wokingham, England Amsterdam Sydney Singapore Tokyo
Madrid Bogota Santiago San Juan

Library of Congress Cataloging-in-Publication Data
Main entry under title:
Amiga hardware reference manual.
Includes index.
1. Amiga (Computer) I. Commodore Business Machines.
QA76.8.A177A65
1986 004.165 85-26650
ISBN 0-201-1io77-6
BCDEFGHIJ-BA-89876
The text of this manual was written by Robert Peck, Susan Deyl, Jay Miner, and Chris Raymond.
Special
thanks to Bill Kolb, Dave Needle, Lee Ho, and Dale Luck.
COPYRIGHT © 1986 by Commodore-Amiga, Inc.
This manual
is copyrighted and all rights are reserved. This document may not, in whole or in part, be copied, photocopied, repro-
duced, translated or reduced to any electronic medium or machine readable form without prior consent,
in writing, from
Commodore-Amiga, Inc.
DISCLAIMERS
COMMODORE-AMIGA, INC., ("COMMODORE") MAKES NO WARRANTIES, EITHER EXPRESSED OR IMPLIED, WITH
RESPECT
TO THE PROGRAMS DESCRIBED HEREIN, THEIR QUALITY, PERFORMANCE, MERCHANTABILITY, OR FIT-
NESS FOR ANY PARTICULAR PURPOSE. THESE PROGRAMS ARE
SOLD "AS IS." THE ENTIRE RISK AS TO THEIR
QUALITY
AND PERFORMANCE IS WITH THE BUYER. SHOULD THE PROGRAMS PROVE DEFECTIVE FOLLOWING
PURCHASE,
THE BUYER (AND NOT THE CREATOR OF THE PROGRAMS, COMMODORE, THEIR DISTRIBUTORS OR
THEIR RETAILERS) ASSUMES THE ENTIRE COST OF
ALL NECESSARY DAMAGES. IN NO EVENT WILL COMMODORE
BE LIABLE FOR DIRECT, INDIRECT, INCIDENTAL OR CONSEQUENTIAL DAMAGES RESULTING FROM ANY DEFECT
IN THE PROGRAMS EVEN IF
IT HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME LAWS DO NOT
ALLOW THE EXCLUSION OR LIMITATION OF IMPLIED WARRANTIES OR LIABILITIES
FOR INCIDENTAL OR CONSE-
QUENTIAL DAMAGES, SO THE ABOVE LIMITATION OR EXCLUSION
MAY NOT APPLY.
THE AMIGA COMPUTER MEETS TITLE 47 OF THE CODE OF FEDERAL REGULATIONS FOR CLASS B COMPUTING
EQUIPMENT. THE FCC STRICTLY FORBIDS THE USE OF UNSHIELDED CABLE
TO ANY AMIGA CONNECTORS WITH
THE EXCEPTION OF
AC POWER. COMMODORE-AMIGA SHALL NOT BE HELD LIABLE FOR INTERFERENCE GEN-
ERATED BY PERIPHERALS NOT AUTHORIZED IN WRITING BY COMMODORE-AMIGA, INC.
Amiga
is a trademark of Commodore-Amiga, Inc.
CBM Product Number 327272-02
Second Printing, July 1986

PREFACE
This manual provides information about the Amiga[tm] graphics and audio hardware
and about how the Amiga talks
to the outside world through peripheral devices. A por-
tion of this manual
is a tutorial on writing assembly language programs to directly con-
trol the Amiga's graphics and hardware.
This book
is intended for the following audiences:
o Assembly language programmers who need a more direct way of interacting with
the system than the routines described
in the Amiga ROM Kernel Manual. You
can find information here to help you make your programs run faster or do
things
that the ROM kernel routines don't do.
o Anyone who wants
to add new peripherals to the Amiga or just wants to know
how the hardware works.
We suggest
that you use this book according to your level of familiarity with the Amiga
system. Here are some suggestions:
o If this is your initial exposure
to the Amiga, read chapter 1, which gives a sur-
vey of all the hardware features and a brief rundown of graphics and audio
effects created by hardware interaction.
o
If you are already familiar with the system and want to acquaint yourself with
how the various bits in the hardware registers govern the way the system func-
tions, browse through chapters 2 through 8. Examples are included in these
chapters.
o For advanced users, the appendixes give a concise summary of the entire register
set and the uses of the individual bits. Once you are familiar with the effects of
changes in the various bits, you may wish
to refer more often to the appendixes
than to the explanatory chapters.
Here is a brief overview of the contents:
Chapter
1, Introduction. An overview of the hardware and survey of the
Amiga's graphics and audio features.
Chapter
2, Coprocessor Hardware. Using the Copper coprocessor to control the
entire graphics and audio system; directing mid-screen modifications
in graphics
displays and directing register changes during the time between displays.
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Chapter 3, Playfield Hardware. Creating, displaying and scrolling the playfields,
one of the basic display elements of the Amiga; how the Amiga produces multi-
color, multi-graphical bit-mapped displays.
Chapter
4, Sprite Hardware. Using the eight sprite direct-memory access (DMA)
channels to make sprite movable objects; creating their data structures, display-
ing and moving them, reusing the
DMA channels.
Chapter
5, Audz'o Hardware. Overview of sampled sound; how to produce qual-
ity sound, simple and complex sounds, and modulated sounds.
Chapter
6, Blitter Hardware. Using the blitter DMA channel to create anima-
tion effects and draw lines into play
fields.
Chapter 7, System Oontrol Hardware. Using the control registers to define
depth arrangement of graphics objects, detect collisions between graphics
objects, control direct memory access, and control interrupts.
Chapter 8, Interface Hardware.
How the Amiga talks to the outside world
through controller ports, keyboard, audio jacks and video connectors, serial and
parallel interfaces; information about the disk controller and RAM expansion
slot.
Appendixes. Alphabetical and address-order listings of all the graphics and
audio system registers and the functions of their bits, system memory map,
descriptions of internal and external connectors, specifications for the peripheral
interface ports, and specifications for the keyboard.
Glossary. After the appendixes, there is a glossary of important terms.
You may wish to look
at the following books and manuals for further information about
the Amiga:
o The Amiga
ROM Kernel Manual contains information about the Exec multitask-
ing routines and is the source for all the C language primitives for Amiga graph-
ics, animation, and audio.
o The following manuals contain information about the AmigaDOS operating sys-
tem:
o AmigaDOS User's Manual
-vi-

o AmigaDOSDeveloper's Manual
o AmigaDOS Technical Reference Manual
It is our policy to make certain that the information contained here is accurate, con-
sistent, and up
to date. If you should find any material confusing, inaccurate, or incom-
plete, please feel free to contact Amiga with your questions or comments.
-vii-

Table of Contents
Chapter 1 INTRODUCTION ............................................................................................ 1
Components of the Amiga ........................................................................................... 1
THE MO 68000 AND THE AMIGA SPEOIAL-PURPOSE
lIARDW
ARE ..................................................................................................................... 2
VOR AND DIREOT OAMERA INTERFAOE
..................................................... 5
PRIMARY AND SEOONDARY MEMORY
......................................................... 5
PERIPHERALS
................................................................................................................ 5
System Expandability and Adaptability .......................................................... 6
Chapter 2 COPROCESSOR HARDWARE .......................................................... 7
Introduction ............................................................................................................................. 7
ABOUT THIS OHAPTER ............................................................................................ 8
What is a Copper Instruction? ................................................................................. 8
The MOVE Instruction
.................................................................................................. 9
The WAIT Instruction .................................................................................................... 11
HORIZONTAL BEAM POSITION .......................................................................... 12
VERTIOAL BEAM POSITION ................................................................................. 12
THE OOMPARISON ENABLE BITS ..................................................................... 13
Using the Copper Registers ......................................................................................... 13
LOOATION REGISTERS ............................................................................................ 13
JUMP STROBE ADDRESS
......................................................................................... 14
OONTROL REGISTER ................................................................................................ 14
Putting Together a Copper Instruction List ................................................. 15
OOMPLETE SAMPLE OOPPER LIST ................................................................. 17
LOOPS AND BRANOHES .......................................................................................... 19
Starting and Stopping the Copper ........................................................................ 19
STARTING
THE OOPPER AFTER RESET ...................................................... 19
STOPPING THE OOPPER ........................................................................................ 19
Advanced Topics ................................................................................................................. 20
THE SI(IP INSTRUOTION ........................................................................................ 20
OOPPER LOOPS AND BRANOHES AND OOMPARISON
ENABLE
.............................................................................................................................. 21
USING
THE COPPER IN INTERLACED MODE ........................................... 22
USING
THE OOPPER WITH THE BLITTER .................................................. 23
THE COPPER AND THE 68000 .............................................................................. 24
Summary of Copper Instructions ........................................................................... 24
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Chapter 3 PLAYFIELD HARDWARE ..................................................................... 27
Introduction .......................................................................................................... ,.................. 27
ABOUT THIS CIIAPTER
............................................................................................ 28
PLAYFIELD FEATURES
............................................................................................ 28
Forming a Basic Playfield ............................................................................................ 33
HEIGHT AND WIDTH
OF THE PLAYFIELD .................................................. 34
BIT-PLANES AND COLOR ....................................................................................... 34
SELECTING RESOLUTION
...................................................................................... 38
ALLOCATING MEMORY
FOR BIT-PLANES .................................................. 41
CODING
THE BIT-PLANES FOR CORRECT COLORING ...................... 44
DEFINING
THE SIZE OF THE DISPLAY WINDOW................................... 46
TELLING
THE SYSTEM HOW TO FETCH AND DISPLAY
DATA
................................................................................................................................... 49
DISPLAYING AND REDISPLAYING THE PLAYFIELD ............................. 52
ENABLING THE COLOR DISPLAY
..................................................................... 52
SUMMARY
......................................................................................................................... 53
EXAMPLES
OF FORMING BASIC PLAYFIELDS .......................................... 55
Forming a Dual-playfield Display .......................................................................... 58
Bit-Plane Assignment in Dual-playfield Mode ............................................. 60
COLOR REGISTERS IN DUAL-PLAYFIELD MODE .................................... 62
DUAL-PLAYFIELD PRIORITY AND CONTROL
........................................... 64
ACTIVATING DUAL-PLAYFIELD MODE
......................................................... 64
SUMMARY
......................................................................................................................... 65
Bit-planes and Display Windows of All Sizes ............................................... 65
WHEN THE BIG PICTURE IS LARGER THAN
THE DISPLAY
WINDOW
........................................................................................................................... 65
MAXIMUM DISPLAY WINDOW SIZE
................................................................. 72
Moving (Scrolling) Playfields ..................................................................................... 73
VERTICAL SCROLLING ............................................................................................ 73
HORIZONTAL SCROLLING
..................................................................................... 74
SUMMARY ......................................................................................................................... 78
Advanced Topics ................................................................................................................. 79
INTERACTIONS- PLAYFIELDS AND OTHER OBJECTS .................... 79
HOLD-AND-MODIFY MODE
.................................................................................... 79
FORMING A DISPLAY WITH SEVERAL DIFFERENT
PLA YFIELDS .................................................................................................................... 82
USING AN EXTERNAL VIDEO SOURCE
......................................................... 82
SUMMARY
OF PLAYFIELD REGISTERS ......................................................... 83
Summary of Color Selection ....................................................................................... 86
COLOR REGISTER CONTENTS ........................................................................... 86
SOME SAMPLE COLOR REGISTER CONTENTS ........................................ 86
COLOR SELEOTION IN LOW-RESOLUTION MODE ................................ 87
COLOR SELEOTION IN HOLD-AND-MODIFY MODE
............................... 89
COLOR SELEOTION IN HIGH-RESOLUTION MODE
................................ 89
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Chapter 4 SPRITE HARDWARE ................................................................................. 91
Introduction ............................................................................................................................. 91
ABOUT THIS ClIAPTER ............................................................................................ 92
Forming a Sprite ................................................................................................................. 92
SCREEN POSITION ...................................................................................................... 92
SIZE OF SPRITES .......................................................................................................... 95
SlIAPE
OF SPRITES ..................................................................................................... 95
SPRITE COLOR
.............................................................................................................. 96
DESIGNING A SPRITE
............................................................................................... 98
BUILDING THE DATA STRUCTURE .................................................................. 99
Displaying a Sprite ............................................................................................................ 104
SELECTING A DMA CHANNEL AND SETTING THE
POINTERS
......................................................................................................................... 105
RESETTING THE ADDRESS POINTERS .......................................................... 106
SPRITE DISPLAY EXAMPLE .................................................................................. 106
Moving a Sprite .................................................................................................................... 108
Creating Additional Sprites ........................................................................................ 110
Reusing Sprite DMA Channels ................................................................................. 111
Overlapped Sprites ............................................................................................................ 114
Attached Sprites ...................................................................................................... ;........... 116
Manual Mode ......................................................................................................................... 119
Sprite Hardware Details ................................................................................................. 120
.Summary of Sprite Registers ..................................................................................... 124
POINTERS ......................................................................................................................... 124
CONTROL REGISTERS ............................................................................................. 125
DATA REGISTERS ........................................................................................................ 126
Summary of Sprite Color Registers ...................................................................... 127
Chapter 5 AUDIO HARDWARE ................................................................................... 131
Introduction ............................................................................................................................. 131
INTRODUCING SOUND GENERATION ........................................................... 132
THE AMIGA SOUND HARDWARE ....................................................................... 135
Forming and Playing a Sound .................................................................................. 136
DECIDING WHICH CHANNEL TO USE ............................................................ 136
CREATING THE WAVEFORM DATA ................................................................ 137
TELLING THE SYSTEM ABOUT THE DATA ................................................ 138
SELECTING THE VOLUME ..................................................................................... 139
SELECTING THE DATA OUTPUT RATE ........................................................ 140
PLAYING THE WAVEFORM ................................................................................... 143
STOPPING THE AUDIO DMA ................................................................................ 144
SUMMARY .... ,.................................................................................................................... 145
EXAMPLE .......................................................................................................................... 145
Producing Complex Sounds ........................................................................................ 147
JOINING TONES ........................................................................................................... 147
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PLAYING MULTIPLE TONES AT THE SAME TIME ................................. 149
MODULATING SOUND
.............................................................................................. 149
Producing High-quality Sound ............................................................................ :.... 152
MAKING WAVEFORM TRANSITIONS
.............................................................. 152
SAMPLING RATE
.......................................................................................................... 152
EFFICIENCY
.................................................................................................................... 153
NOISE REDUCTION
..................................................................................................... 154
ALIASING DISTORTION
........................................................................................... 154
LOW-PASS FIL
TER ................................................................ ,...................................... 156
Using Direct (Non-DMA) Audio Output .......................................................... 157
The Equal-tempered Musical Scale ....................................................................... 158
Decibel Values for Volume Ranges ....................................................................... 160
The Audio State Machine ............................................................................................ 161
Chapter 6 BLITTER HARDWARE ............................................................................ 165
Introduction ............................................................................................................................. 165
Data Copying ......................................................................................................................... 167
Pointers and Modulos ...................................................................................................... 168
Ascending and Descending Addressing .............................................................. 170
Rectangular or Linear Address Scanning ......................................................... 171
Blitter Logic Operations ................................................................................................ 171
DESIGNING THE LF CONTROL BYTE WITH LOGIC
EQUATIONS
................................................... ................................................................. 172
DESIGNING THE LF CONTROL BYTE WITH VENN
DIAGRAMS
........................................................................................................................ 175
Shifting ........................................................................................................................................ 177
Masking ...................................................................................................................................... 178
Zero Detection ....................................................................................................................... 179
Area Filling .............................................................................................................................. 180
INCLUSIVE (NORMAL) AREA FILLING
........................................................... 180
EXCLUSIVE AREA FILLING
.................................................................................... 182
Line Drawing .......................................................................................................................... 1$3
OCTANTS IN LINE DRAWING
.............................................................................. 184
Blitter Operations and System DMA .................................................................. 186
BLITTER DMA PRIORITY
........................................................................................ 186
DMA TIME SLOT ALLOCATION
.......................................................................... 186
BIT-PLANE/PROCESSOR BUS SHARING
........................................................ 189
EFFECTS
OF DIFFERENT DISPLAY SIZES ................................................... 191
EFFECTS OF BLITTER OPERATION
................................................................ 191
Complete Blitter Example ........................................................................................... 193
Blitter Block Diagram ..................................................................................................... 195
-xii-