DA11-B DMA UNIBUS Link
The DA11-B DMA UNIBUS Link allows two UNIBUSes to be directly connected; either single words, or blocks of up to 32K words, can be transferred. The channel is half-duplex. Although the DA11-B can generate interrupts on either UNIBUS (in response to user commands given directly to it via its Control and Status Register), it cannot transfer interrupts (i.e. from one UNIBUS to the other).
In Block Mode, the DA11-B uses DMA on the source bus to read words in the block, and then uses DMA on the other UNIBUS to write the data.
The DA11-B is built out of a pair of DR11-B parallel interfaces, each taking a system unit backplane in each computer. An M7229 buffer module is installed in each DR11-B's user connection slot, CD0.
Registers
| Register | Address |
|---|---|
| Word count Register | XXXX00 |
| Bus Address Register | XXXX02 |
| Control and Status Register | XXXX04 |
| Data Buffer Register | XXXX06 |
The first DA11-B in a system is usually assigned register addresses starting with 0772410.
External links
- DR11-B/DA11-B manual (EK-DR11B-TM-004) - the DA11-B is covered in Appendix C
- pdp11 peripherals handbook - the DA11-B is covered on pp. 83-87
