DB11-A Bus Repeater
The DB11-A Bus Repeater allows a UNIBUS to double the number of peripherals connected to the bus (in terms of the combined analog load).
It terminates (in analog terms) the first section of the bus, and active digital logic repeats all the signals though onto the second section (or from the second back to the first, when required); the two sections are thus logically connected, but not in purely analog terms.
It consists of a custom system unit backplane, holding a number of smaller FLIP CHIPs; mostly singles (see table below), with one dual (M7213).
| Type | Count | Function |
|---|---|---|
| M783 | 1 | Bus driver |
| M784 | 1 | Bus receiver |
| M785 | 4 | Bus transceiver |
| M7212 | 3 | Address buffer |
| M7213 | 1 | Buffer master |
| M7248 | 1 | BBSY repeater |
| M930 | 2 | UNIBUS terminator |
Board locations (as seen from the board insertion side of the backplane, not the wire-wrap pin side, as is common in DEC documentation) are:
| Connector | ||||||
|---|---|---|---|---|---|---|
| Slot | A | B | C | D | E | F |
| 1 | UNIBUS A In | M7248 | M7212 | M7212 | M7212 | |
| 2 | UNIBUS A termination | Unused | M784 | M783 | ||
| 3 | Power | Unused | M7213 | M785 | M785 | |
| 4 | UNIBUS B Out | UNIBUS B termination | M785 | M785 | ||
For installation in later BA11 mounting boxes, the paddle card of a G772 system unit harness adaptor can be plugged into the 3A slot; the DEC power distribution connectors on the other end of the adaptor plug into those of the BA11.
External links
- DB11-A bus repeater manual - (EK-DB11A-TM-002)
- DB11-A Engineering Drawings - Various bus drivers, repeaters and terminators
