DR11-C general device interface

DR11-C board

The DR11-C general device interface was a UNIBUS device controller which provided a pair of 16-bit parallel ports, one input, and one output. It was a quad format card (M7860), and used an SPC slot; it used programmed I/O.

Connection to the user's device is via a pair of 40-pin Berg connectors. A pair of optional single-width paddle cards (M971) may be connected via flat cables. Data going out to the user's device was latched in the DR11-C, so may be read at leisure; data coming in from the user's device was merely sampled by the DR11-c, so must be held until it has been read.

The DR11-C is the replacement for the earlier multi-board DR11-A General Device Interface. The DR11-C is slightly enhanced over the DR11-A (the -A does not have the CSR1/CSR0 bits).

Registers

The device has three control and buffer registers, which can be configured to any three sequential word locations in the I/O page; the first DR11-C is normally configured to addresses 767770-767774:

Register	Abbreviation	Address
Control and Status Register	DRCSR	767770
Output Buffer Register	DROUTBUF	767772
Input Buffer Register	DRINBUF	767774

In the register contents (below), bits which are read/write or unused are shown in normal font, those which are read-only are in italics.

Status Register (DRCSR)

REQ B	Unused							REQ A	INT ENB A	INT ENB B	Unused			CSR1	CSR0
15	14	13	12	11	10	09	08	07	06	05	04	03	02	01	00

• REQ B - Request B - Signal from user's hardware which can be tested, or cause an interrupt (below)
• REQ A - Request A
• INT ENB A - Interrupt Enable A - When set, allows setting REQ A to cause an interrupt
• INT ENB B - Interrupt Enable B
• CSR1 - Signal to user's hardware (on connector 1)
• CSR0 - Signal to user's hardware (on connector 2)

Output Buffer Register (DROUTBUF)

OUT15 <-> OUT0
15	14	13	12	11	10	09	08	07	06	05	04	03	02	01	00

Input Buffer Register (INBUF)

IN15 <-> IN0
15	14	13	12	11	10	09	08	07	06	05	04	03	02	01	00