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BEAM POSITION DETECTION
Sometimes you might want to synchronize the 68000 processor to the video beam that is
creating the screen display. In some cases, you may also wish to update a part of the
display memory after the system has already accessed the data from the memory for the
display area.
The address for accessing the beam counter is provided so that you can determine the
value of the video beam counter and perform certain operations based on the beam
position.
NOTE
The Copper is already capable of watching the display position for you and doing certain
register-based operations automatically. Refer to "Copper Interrupts" below and Chapter
2, "Coprocessor Hardware," for further information.
In addition, when you are using a light pen with this system, this same address is used to
read the light pen position rather than the beam position. This is described fully in Chapter
8, "Interface Hardware."
USING THE BEAM POSITION COUNTER
There are four addresses that access the beam position counter. Their usage is described
in Table 7-5.
- 210 System Control Hardware -
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...