Digital Equipment Corporation PDP-7/A - S#114

Applied Data Research (ADR), Princeton NJ

The PDP-7 Service list (1972) shows that machine #114 (DEC #999999) was a PDP-7/A shipped to Applied Data Research (ADR), Princeton, New Jersey in February 1966 and consisted of the following options -

OptionS#ShipDEC #Notes
14900007502669999994K memory upgrade to 8K
14900007602660000004K memory upgrade to 12K
177B0000340266000000Extended Arithmetic Element
550A0000490266000000DECtape dual magnetic tape transport control
CR01B0000050266000000Card Reader and Control
KA71A0000140266000000I/O device package
KA77A0000140266000000Processor unit
TU550001140266000000Single DECtape transport
TU550001160266000000Single DECtape transport
TU550002360266015585Single DECtape transport

For descriptions of the above options see the full PDP-7 options list.

9/3/2016 - In a recent email Robert Supnik wrote about system #114 -
"Hi Mike.
I can give you the history of PDP-7/A serial #114 at Applied Data Research (ADR), Princeton, NJ, where I worked as a summer intern 1964-1968.
The PDP7 was bought as a program development environment or big brother to a DEC 338 (PDP8 + display subsystem), which was used for both real-time development and a government-funded research program. It had 16KW, EAE, card reader, DECtapes, a non-DEC printer from Potter, and a PDP7-PDP8 interprocessor link. It ran DECsys, DEC's primitive DECtape based OS. ADR enhanced DECsys to improve its IO and wrote cross-development tools and a PDP8 simulator for PDP8 development. Some of the sources still survive - the SimH[1] web site has the PDP8 simulator, for example. In 1969, ADR acquired a PDP-10 for development. After that, the PDP7 was no longer needed. In the early 70s, it was sent to the ADR branch office in Wakefield, MA, and eventually returned to DEC, where it was apparently scrapped.

120 PDP-7 and PDP-7/A systems were forecast to be built in total, but the 1972 18-bit service list available (6.5Mb pdf download) with only has details of the 99 known PDP-7 and PDP-7/A systems in the list at that time.  We do not have any information about the possible remaining 21 systems, who they were delivered to or even if they actually existed.

The PDP-7 appeared to have sold well into Government research and University sectors with 11 systems shipped to the UK alone, almost 10% of the forecast production run!  Serial numbers are concurrent for both PDP-7's and the PDP-7/A's, so the missing 21 could be of either type; however we are reasonably confident that the 99 systems shipped were the only ones that were ever built.

If you know of any information about any of the PDP-7 systems worldwide, options, location of existing systems, spare parts, ancillary bits, software, tapes or manuals, then please contact us.

Documents associated with PDP-7/A S#114 - None at this time


  1. SimH - The Computer History Simulation Project is a loose Internet-based collective of people interested in restoring historically significant computer hardware and software systems by simulation. The goal of the project is to create highly portable system simulators and to publish them as freeware on the Internet, with freely available copies of significant or representative software - weblink [back] [top]

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