src/mess/drivers/supracan.c
| r8321 | r8322 | |
|---|
| 42 | 42 | [ff7be4] <- 0x269ec |
| 43 | 43 | bpclear |
| 44 | 44 | |
| 45 | Sound notes: |
| 46 | |
| 47 | There are 6 interrupt sources on the 6502 side, all of which use the IRQ line. |
| 48 | The register at 0x411 is bitmapped to indicate what source(s) are active. |
| 49 | In priority order from most to least important, they are: |
| 50 | |
| 51 | 411 value How acked Notes |
| 52 | 0x40 read reg 0x16 of sound chip likely timer. snd regs 0x16/0x17 are time constant, write 0 to reg 0x9f to start |
| 53 | 0x04 read at 0x405 latch 1? 0xcd is magic value |
| 54 | 0x08 read at 0x404 latch 2? 0xcd is magic value |
| 55 | 0x10 read at 0x409 unknown, dispatched but not used in startup 6502 code |
| 56 | 0x20 read at 0x40a possible periodic like vblank? |
| 57 | 0x80 read reg 0x14 of sound chip depends on reg 0x14 of sound chip & 0x40: if not set writes 0x8f to reg 0x14, |
| 58 | otherwise writes 0x4f to reg 0x14 and performs additional processing |
| 59 | |
| 45 | 60 | ***************************************************************************/ |
| 46 | 61 | |
| 47 | 62 | #include "emu.h" |