DEC PDP-11/10

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I have two PDP-11/10 units.

The first one has been upgraded to MOS memory before I received it.

The second one still uses core memory.

Both are in working order (or at least they were in working order when I last tested them).

PDP-11/10 with MOS memory

This is a very bare-bones system.

It has 3 backplanes (9-slot, 9-slot and 4-slot). The second backplane holds a hex-height MOS memory board. I was told this machine uses a “Modified UNIBUS backplane”. I am not sure whether this affects all 3 backplanes, or just the second one. Care needs to be taken here.

The backplanes are fitted with the following cards (excluding M920 UNIBUS connectors and grant continuity cards):

Backplane 1:

  • Slot 1: AB = empty. CD = M9970. EF=Empty
  • Slot 2: AF = M7260
  • Slot 3: AF = M7261
  • Slot 4: AB = M930 (terminator?). CF = Empty
  • Slot 5-9: Empty

Backplane 2:

  • Slot 4: Plessey P/N 701295-???F (128KW MOS Memory board)
  • Slot 6: M7867 (synchronous modem interface)

Unfortunately the suffix on the part number for the Plessey MOS Memory board is unreadable. The board is fitted with 4 rows of 18 x 4116 dynamic RAM chips. I guess this means it has 64KW of parity RAM. That’s a bit surprising, given that the PDP-11/10 only has a 16-bit address space. I need to investigate this further. It has one 10-way dipswitch on the board. Switches 1-7 and 9 are ON. Switches 8 & 10 are OFF.

The DUP11 is a synchronous modem interface. It operates under various protocols (SDLC, ADCCP, DDCMP, etc). The User’s Manual for the DUP11 is available on bitsavers here -> ftp://bitsavers.informatik.uni-stuttgart.de/pdf/dec/unibus/EK-DUP11-OP_DUP11UM_Nov76.pdf

Some grant continuity cards are fitted, but many appear to be missing. There is no terminator at the end of the final (third) backplane.

PDP-11/10 with core memory

This system is setup as a paper tape (ASR33) and cassette (TU60) system).

It has a bootloader card for the TU60, which resides at 177300. I still need to add a bootloader card for the paper tape system, which will reside at 177000.

It has 2 backplanes (9-slot, and 4-slot). 12KW of 16-bit core memory is fitted.

The backplanes are fitted with the following cards (excluding grant continuity cards):

Backplane 1:

  • Slot 1: AB = empty. CD = M9970. EF=Empty
  • Slot 2: AF = M7260
  • Slot 3: AF = M7261
  • Slot 4: AB = small unidentified board (terminator?). CF = H214 (8Kx16 Memory Stack)
  • Slot 5: AF = G110 (Control and Data Loops)
  • Slot 6: AF = G231 (Memory Driver)
  • Slot 7: AF = G231 (Memory Driver)
  • Slot 8: AF = G110 (Control and Data Loops)
  • Slot 9: AB = M920 UNIBUS jumper. CF = H213 (4Kx16 Memory Stack)

Backplane 2:

  • Slot 1: AB = M920 UNIBUS jumper. CF = empty
  • Slot 2: AB = empty. CF = M792 (BM792-YH TA11 Bootstrap Loader)
  • Slot 3: AF = empty
  • Slot 4: AB = M930C (terminator?). CF = M7892 (TU60 Interface)

Most grant continuity cards are fitted, and there is one spare in the bottom of the enclosure.