The Description-Based Direct Memory Access (DBDMA) relies on memory-based descriptions, minimizing CPU interrupts.
| Channel |
Number |
| SCSI0 |
0x0 |
| FLOPPY |
0x1 |
| ETHERNET TRANSMIT |
0x2 |
| ETHERNET RECIEVE |
0x3 |
| SCC TRANSMIT A |
0x4 |
| SCC RECIEVE A |
0x5 |
| SCC TRANSMIT B |
0x6 |
| SCC RECIEVE B |
0x7 |
| AUDIO OUT |
0x8 |
| AUDIO IN |
0x9 |
| SCSI1 |
0xA |
| Register |
Offset |
| ChannelControl |
0x00 |
| ChannelStatus |
0x04 |
| CommandPtrLo |
0x0C |
| InterruptSelect |
0x10 |
| BranchSelect |
0x14 |
| WaitSelect |
0x18 |
| Command |
Value |
| OUTPUT_MORE |
0x0 |
| OUTPUT_LAST |
0x1 |
| INPUT_MORE |
0x2 |
| INPUT_LAST |
0x3 |
| STORE_QUAD |
0x4 |
| LOAD_QUAD |
0x5 |
| NOP |
0x6 |
| STOP |
0x7 |
| Key Name |
Value |
| KEY_STREAM0 |
0x0 |
| KEY_STREAM1 |
0x1 |
| KEY_STREAM2 |
0x2 |
| KEY_STREAM3 |
0x3 |
| KEY_REGS |
0x5 |
| KEY_SYSTEM |
0x6 |
| KEY_DEVICE |
0x7 |
References
