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INTREQ
Interrupt request (status) - write only. Used by the processor to force a certain kind of
interrupt to be processed (software interrupt). Also used to clear interrupt request flags
once the interrupt process is completed.
INIEQR
Interrupt request (status) read - read only. Contains the bits that define which items are
requesting interrupt service.
The bit positions in the interrupt request register correspond directly to those same
positions in the interrupt enable register. The only difference between the read-only and
the write-only addresses shown above is bit 15 has no meaning in the read-only
addresses.
SETTING AND CLEARING BITS
Below are the meanings of the bits in the interrupt control registers and how you use
them.
SET AND CLEAR
The interrupt registers, as well as the DMA control register, use a special way of selecting
which of the bits are to be set or cleared. Bit 15 of these registers is called the SET/CLR
bit.
When you wish to set a bit (make it a 1), you must place a 1 in the position you want to
set and a 1 into position 15.
When you wish to clear a bit (make it a 0), you must place a 1 in the position you wish to
clear and a 0 into position 15.
Positions 14-0 are bit-selectors. You write a 1 to any one or more bits to select that bit. At
the same time you write a 1 or 0 to bit 15 to either set or clear the bits you have selected.
Positions 14-0 that have 0 value will not be affected when you do the write. If you want to
set some bits and clear others, you will have to write this register twice (once for setting
some bits, once for clearing others).
- System Control Hardware 213 -
Содержание Amiga A1000
Страница 1: ...AMIGA HARDWARE REFERENCE MANUAL 1992 Commodore Business Machines Amiga 1200 PAL...
Страница 20: ...Figure 1 1 Block Diagram for the Amiga Computer Family Introduction 11...
Страница 21: ...12 Introduction...
Страница 72: ...Figure 3 12 A dual Playfield display Playfield Hardware 63...
Страница 87: ...Figure 3 24 Horizontal Scrolling 78 playfield hardware...
Страница 101: ...92 Playfield Hardware...
Страница 199: ...Figure 6 9 DMA time slot allocation 190 Blitter hardware...
Страница 203: ...Figure 6 13 Blitter Block Diagram 194 Blitter Hardware...
Страница 229: ...220 System Control Hardware...
Страница 246: ...Figure 8 8 Chinon Timing diagram cont Interface Hardware 237...
Страница 265: ...256 Interface Hardware...
Страница 289: ...280 Appendix A...
Страница 297: ...288 Appendix B...
Страница 298: ...APPENDIX C CUSTOM CHIP PIN ALLOCATION LIST NOTE Means an active low signal Appendix C 289...
Страница 302: ...APPENDIX D SYSTEM MEMORY MAP Appendix D 293...
Страница 343: ...334 Appendix F...
Страница 351: ...342 Appendix G...
Страница 361: ...352 Appendix H...
Страница 367: ...358 Appendix I...