DMA stands for Direct Memory Access, referring to the ability of peripherial hardware to directly access memory, independant of the CPU.
DMA registers
| Address | Name |
| 0x040000B0:32 | R/W | DMA0_SRC (0ffffffe) |
| 0x040000B4:32 | R/W | DMA0_DST (0ffffffe) |
| 0x040000B8:32 | R/W | DMA0_CR (ffffffff) |
| 0x040000BC:32 | R/W | DMA1_SRC (0ffffffe) |
| 0x040000C0:32 | R/W | DMA1_DST (0ffffffe) |
| 0x040000C4:32 | R/W | DMA1_CR (ffffffff) |
| 0x040000C8:32 | R/W | DMA2_SRC (0ffffffe) |
| 0x040000CC:32 | R/W | DMA2_DST (0ffffffe) |
| 0x040000D0:32 | R/W | DMA2_CR (ffffffff) |
| 0x040000D4:32 | R/W | DMA3_SRC (0ffffffe) |
| 0x040000D8:32 | R/W | DMA3_DST (0ffffffe) |
| 0x040000DC:32 | R/W | DMA3_CR (ffffffff) |
Format of the control registers:
Enable:
- W0: Stop DMA
- W1: Activate DMA
- R1: Busy
- R0: Ready
Size:
- 0: Halfword (16 bits)
- 1: Word (32 bits)
Timing mode:
- 0: Immediately
- 1: Wait until V-Blank
- 2: Wait until H-Blank
- 3: Display synchronize
- 4: ?
- 5: Card
- 6: ?
- 7: ?
Source mode:
- 0: Increment
- 1: Decrement
- 2: Fixed
- 3: Undefined
Destination mode:
- 0: Increment
- 1: Decrement
- 2: Fixed
- 3: Increment, but reload on completion