From Computer History Wiki
Jump to: navigation, search

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 was produced by DEC's Computer Special System division; it was 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.


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