Commodore Amiga A1000, Hardware Reference Manual

Page: 5 / 380

HOW COLLISIONS ARE DETERMINED........................207
HOW TO INTERPRET THE COLLISION DATA .................208
HOW COLLISION DETECTION IS CONTROLLED ...............209
Beam Position Detection.................................210
USING THE BEAM POSITION COUNTER......................210
Interrupts .............................................211
NONMASKABLE INTERRUPT ...............................212
MASKABLE INTERRUPTS..................................212
USER INTERFACE TO THE INTERRUPT SYSTEM ..............212
INTERRUPT CONTROL REGISTERS .........................212
SETTING AND CLEARING BITS............................213
DMA Control ............................................217
Processor Access to Chip Memory.........................217
Reset and Early Startup Operation.......................219
Chapter 8 INTERFACE HARDWARE..............................221
Introduction............................................221
Controller Port Interface...............................222
REGISTERS USED WITH THE CONTROLLER PORT..............223
Floppy Disk Controller .....,.............................235
REGISTERS USED BY THE DISK SUBSYSTEM ................236
DISK INTERRUPTS .....................................244
The Keyboard............................................245
HOW THE KEYBOARD DATA IS RECEIVED....................245
TYPE OF DATA RECEIVED................................245
LIMITATIONS OF THE KEYBOARD .........................247
Parallel Input/Output Interface.........................250
Serial Interface .......................................250
INTRODUCTION TO SERIAL CIRCUITRY ....................250
SETTING THE BAUD RATE................................250
SETTING THE RECEIVE MODE ............................251
CONTENTS OF THE RECEIVE DATA REGISTER................251
HOW OUTPUT DATA IS TRANSMITTED.......................253
SPECIFYING THE REGISTER CONTENTS ....................254
Display Output Connections .............................255
Appendix A Register Summary-Alphabetical Order............257
Appendix B Register Summary-Address Order.................281
Appendix C Custom Chip Pin Allocation List................289
Appendix D System Memory Map..............................293
Appendix E Interfaces ....................................295
Appendix F Complex Interface Adapters.....................317
8520 Complex Interface Adaptor (CIA) Chips..............317
Chip Register Map.......................................319
Register Functional Description.........................320
I/O PORTS (PRA, PRB, DDRA, DDRB).....................320
HANDSHAKING..........................................320
INTERVAL TIMERS (TIMER A, TIMER B)...................320
INPUT MODES..........................................322
BIT NAMES on READ-Register...........................322
BIT NAMES on WRITE-Register .........................322
Time of Day Clock.......................................323
BIT NAMES for WRITE TIME/ALARM or READ TIME..........323
Serial Shift Register (SDR).............................324