UNIBUS
The PDP-11 computer bus, the predecessor of the more modern QBUS.
It was also used in the Eastern bloc (SMEP, JPR 12R, ...), but its physical connection is incompatible.
The L at the end indicates an inverted signal ("active low"). Some schemes (JPR 12R, etc.) use the prefix "BUS" for the UNIBUS bus, i.e. eg "BUS A 05 L" is "A 05 L", somewhere "B" is also used ("B INIT L" etc.). In modern diagrams created in CAD, you can also find inversion markings at the beginning instead of L at the end - e.g. /A05.
- A[00..17] L - address bus
- D[00..15] L - data bus
- BR[4..7] L - BUS Request signal
- BG[4..7] H - BUS Grant signal
- ACLO L
- BBSY L
- C0 L
- C1 L
- DCLO L
- INIT L - reset signal.
- INTR L
- MSYN L
- NPG H
- NPR L
- PA L
- PB L
- SACK L
- SSYN L
Connection of UNIBUS cards PDP/11
5.18" (13.5 cm) x 4.68" (11.88 cm) card with two side connectors (A,B). The second letter indicates the pin (A..V), the third number in the sequence indicates the side of the card.
- INIT L AA1
- +5V AA2
- INTR L AB1
- GND AB2
- D00 L AC1
- GND AC2
- D02 L AD1
- D01 L AD2
- D04 L AE1
- D03 L AE2
- D06 L AF1
- DO5 L AF2
- DO8 L AH1
- D07 L AH2
- D10 L AJ1
- D09 L AJ2
- D11 L AK2
- D12 L AKI
- D14 L AL1
- D13 L AL2
- PA L AM1
- D15 L AM2
- GND AN1
- PB L AN2
- GND AP1
- BBSY L AP2
- GND AR1
- SACK L AR2
- GND AS1
- NPR L AS2
- GND AT1
- BR7 L AT2
- NPG H AU1
- BR6 L AU2
- BG7 H AV1
- GND AV2
- BG6 H BA1
- +5 V BA2
- BGSH BB1
- GND BB2
- BR5 L BC1
- GND BC2
- GND BD1
- BR4 L BD2
- GND BE1
- BG4 H BE2
- ACLO L BF1
- DCLO L BF2
- A01 L BH1
- A00 L BH2
- A03 L BJ1
- A02 L BJ2
- A05 L BK1
- A04 L BK2
- A07 L BL1
- A06 L BL2
- A09 L BM1
- A08 L BM2
- A11 L BN1
- A10 L BN2
- A13 L BP1
- A12 L BP2
- A15 L BR1
- A14 L BR2
- A17 L BS1
- A16 L BS2
- GND BT1
- C1 L BT2
- SSYN L BU1
- C0 L BU2
- MSYN L BV1
- GND BV2
The UBM (universal interface block, such a "backplane") is unified and consists of four positions (R1 - R4) for three-connector (K1, K2, K3) boards. And the first and last positions are only for double connectors (so-called 2/3 boards), if the bus goes to and from the next UBM (K1). So it is realistically possible to install three-connector (so-called 3/3 boards) only in the two middle positions. We are talking about general boards with a common bus, such as ASAD, PAD, QASAD, etc. Most of the other specialists had to have their own "BM" - bus boards. E.g. older tape drive controller, cassette disk controller, etc. These could not be inserted into standard UBM.