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INSTRUCTION EXPLANATION
[ ... other instructions ... ]
WAIT for position (0,255) At this point, the vertical
counter appears to wrap to 0
because the comparison works
on the least significant bits
of the vertical count.
WAIT for any horizontal position with Thus the total of 256+6 = 262
vertical position 0 through 256, covering lines of video beam travel
the last 6 lines of the scan before vertical during which Copper
blanking occurs. instructions can be executed.
NOTE
The vertical is like the horizontal - as there are alternating long and short lines, there are
also long and short fields (interlace only). In NTSC, the fields are 262, then 263 lines and
in PAL, 312,313.
This alteration of lines & fields produces the standard NTSC 4 field repeating pattern:
short field ending on short line
long field ending on long line
short field ending on long line
long field ending on short line
& back to the beginning...
1 horizontal count takes 1 cycle of the system clock. (Processor is twice this)
NTSC- 3,579,545 Hz
PAL- 3,546,895 Hz
genlocked- basic clock frequency plus or minus about 2%.
THE COMPARISON ENABLE BITS
Bits 14-1 are normally set to all 1s. The use of the comparison enable bits is described
later in the "Advanced Topics " section.
- Coprocessor Hardware 19 -
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...