DRV11-B Direct Memory Access Interface

The DRV11-B Direct Memory Access Interface is a parallel port device controller for the QBUS which provided a pair of 16-bit parallel ports, one input, and one output; it uses DMA to transfer data.

It is effectively a half duplex device; it has only a single pair of bus address and word count registers. Directional control is by the user's device specifying whether each cycle is a DATI, DATO, or DATIO.

It was a quad format card (M7950); connection to the user's device is via a pair of 40-pin Berg connectors.

Registers

The device has five control and buffer registers, which can be configured to any group of four sequential word locations in the I/O page; the first DRV11-B is normally configured to addresses 772410-72416. The two buffer registers share an address, responding to read or write cycles as the case might be.

Register	Abbreviation	Address
Bus Address Register	DRBAR	767770
Word Count Register	DRWCR	767772
Control and Status Register	DRCSR	767774
Input Data Buffer Register	DRINBUF	767776 (read)
Output Data Buffer Register	DROUTBUF	767776 (write)