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DEC PDP-11/40

This DC PDP-11/40 was donated by Dr. Douglas Lyon of Fairfield University on 6/20/16. It has Yale University inventory stickers on it, so it probably started life there.

It includes a Data Systems Design 880 drive subsystem with an 8" floppy disk / 7.8 MB 8" disk drive, and a Standard Logic FD8200-2 dual 8" diskette subsystem. The oscilloscope is a Tektronix RM-504 with 450 KHz bandwidth from the early 1960s. A Trygon Electronics model RS40-10 power supply is below the oscilloscope, and custom switch panel is to the right.

At some point in this system's life it was modified to accept a PDP-11/23 board set. The original PDP-11/40 CPU is Unibus based and the PDP-11/23 is Q-bus, so the backplane was replaced. A custom board was made to interface the PDP-11/23 CPU to the original PDP-11/40 front panel. The Q-Bus boards in this system from front to back are:
  • M8186, KDF11-A, 11/23 CPU, 18-bit addressing only
  • M8044-DM, MSV11-DD, 32-Kword 16-bit MOS RAM
  • M8043, DLVJ1-M, 4-Line Asynchronous Interface
  • M7940, DLV11, Serial Line Unit (SLU, Async)
  • A custom interface to the front panel.
Click on the image for a larger view.
This is the custom board to connect the PDP-11/23 processor to the PDP-11/40 front panel.

Click on the image for a larger view.

Click on the image for a larger view.
These are the Q-Bus boards.
The board at the bottom right is the custom 11/40 front panel interface.

Click on the image for a larger view.
The unusual hex-wide LSI-11 backplane.
This might be a DEC DDV11-B backplane.




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