DRV11-J High-Density Parallel Interface
The DRV11-J High-Density Parallel Interface was a QBUS parallel interface device controller which provided four bi-directional 16-bit parallel ports. It was a dual format card (M8049). It used programmed I/O; the direction of each port was programmable. It was not program compatible with any other DEC parallel port controller.
Connection to the user's device was via a pair of 50-pin Berg connectors; PORTS A and B through the bottom connector (furthest from the insertion handles), ports C an D via the top. Data going out to the user's device was latched in the DRV11-J, so may be read at leisure; data coming in from the user's device was merely sampled by the DRV11-J, so must be held until it has been read.
Registers
The device had four pairs of control and buffer registers, which could be configured to any eight sequential word locations in the I/O page. The first DRV11-J was normally configured to addresses 764160-764176; the second to 764140-767756, the third to 764120-767736, and so on.
| Register | Abbreviation | Address |
|---|---|---|
| Control and Status Register A | DRCSRA | 764160 |
| Data Buffer Register A | DRDBRA | 764162 |
| Control and Status Register B | DRCSRB | 764164 |
| Data Buffer Register B | DRDBRB | 764166 |
| Control and Status Register C | DRCSRC | 764170 |
| Data Buffer Register C | DRDBRC | 764172 |
| Control and Status Register D | DRCSRD | 764174 |
| Data Buffer Register D | DRDBRD | 764176 |
