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This DEC 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.
As received 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 all of PDP-11/40 CPU, Memory, and I/O boards were removed. They installed a PDP-11/23 board set and a hex-wide Q-Bus backplane. A custom wire-wrap 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.
Our plan is to use this equipment to build a complete PDP-11/40 that can run all of the DEC operating systems and UNIX.
November 2025
All of this equipment was used to make a new PDP-11/40 #2.
This is the custom board to connect the PDP-11/23 processor to the PDP-11/40 front panel.
The unusual hex-wide LSI-11 backplane.
This might be a DEC DDV11-B backplane.
These are the Q-Bus boards.
The board at the bottom right is the custom 11/40 front panel interface.
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