NOTE
At the start of each vertical blanking interval, COP1LC is automatically used to start the
program counter. That is, no matter what the Copper is doing, when the end of vertical
blanking occurs, the Copper is automatically forced to restart its operations at the address
contained in COP1LC.
JUMP STROBE ADDRESS
When you write to a Copper strobe address, the Copper reloads its program counter from
the corresponding location register. The Copper can write its own location registers and
strobe addresses to perform programmed jumps. For instance, you might MOVE an
indirect address into the COP2LC location register. Then, any MOVE instruction that
addresses COPJMP2 strobes this indirect address into the program counter.
There are two jump strobe addresses:
COPJMP1 Restart Copper from address contained in COP1LC.
COPJMP2 Restart Copper from address contained in COP2LC.
CONTROL REGISTER
The Copper can access some special-purpose registers all of the time, some registers only
when a special control bit is set to a 1, some registers not at all. The registers that the
Copper can always affect are numbered $20 through $FF inclusive. Those it cannot affect
at all are numbered $00 to $0F inclusive. (See Appendix B for a list of registers
in address order.) The Copper control register is within this group ($00 to $0F). Thus it
takes deliberate action on the part of the 68000 to allow the Copper to write into a
specific range of the special-purpose registers.
The Copper control register, called COPCON, contains only one bit, bit #1. This bit, called
CDANG (for Copper Danger Bit) protects all registers numbered between $10 and $1F
inclusive. This range includes the blitter control registers. When CDANG is 0, these
registers cannot be written by the Copper. When CDANG is 1, these registers can be
written by the Copper. Preventing the Copper from accessing the blitter control registers
prevents a "runaway" Copper (caused by a poorly formed instruction list) from
accidentally affecting system memory.
NOTE
The CDANG bit is cleared after a reset.
- Coprocessor Hardware 21 -
Summary of Contents for Amiga A1000
Page 1: ...AMIGA HARDWARE REFERENCE MANUAL 1992 Commodore Business Machines Amiga 1200 PAL...
Page 20: ...Figure 1 1 Block Diagram for the Amiga Computer Family Introduction 11...
Page 21: ...12 Introduction...
Page 72: ...Figure 3 12 A dual Playfield display Playfield Hardware 63...
Page 87: ...Figure 3 24 Horizontal Scrolling 78 playfield hardware...
Page 101: ...92 Playfield Hardware...
Page 199: ...Figure 6 9 DMA time slot allocation 190 Blitter hardware...
Page 203: ...Figure 6 13 Blitter Block Diagram 194 Blitter Hardware...
Page 229: ...220 System Control Hardware...
Page 246: ...Figure 8 8 Chinon Timing diagram cont Interface Hardware 237...
Page 265: ...256 Interface Hardware...
Page 289: ...280 Appendix A...
Page 297: ...288 Appendix B...
Page 298: ...APPENDIX C CUSTOM CHIP PIN ALLOCATION LIST NOTE Means an active low signal Appendix C 289...
Page 302: ...APPENDIX D SYSTEM MEMORY MAP Appendix D 293...
Page 343: ...334 Appendix F...
Page 351: ...342 Appendix G...
Page 361: ...352 Appendix H...
Page 367: ...358 Appendix I...
