System Number 319

The PDP-9 was a follow on to the highly successful DEC PDP-7 series of computers. While there were some differences, one of the PDP-9 system utilities would convert PDP-7 programs to run on the PDP-9. Input was by paper or magnetic tape.

This system was purchased by Max Levy Autograph in October 1968 and shipped to Concord Controls who designed and built the controller for the 60" photo-plotter. This was one of the largest such devices in the world. It was used to prepare glass for etching as filters and measuring templates. The photo-plotter rested on a five foot thick granite slab, with supports set in bedrock. The PDP-9 and photo-plotter was then shipped to of Philadelphia, PA and ran 24/7 from 1968 to the summer of 1999. When the memory limitations of the PDP-9 caused problems with programming they bought a PDP-11/23 and connected it to the PDP-9 through a special I/O controller that was added to the plotter controller.

We were contacted by Ted Heimberger, the person who operated this system for 30 years. He filled us in on much of the history of the system and will come to the RICM for a visit. The notes that are taped to the front of the system are his.

This PDP-9 was located for the RICM by Kevin Stumpf, and donated by Max Levy Autograph of Philadelphia, PA. A total of 445 PDP-9 systems were produced, and so far, only nine are known to have survived.

The current locations of these nine include a PDP-9 and a PDP-9/L in California, one in Australia that came from La Trobe University in Melbourne, one in Germany, one in Great Britain, two in France, two in Sweden and a new one #203, and of course our own, seen below. Parts of #209 that was delivered to Australia Iron & Steel were recently found. There are lots of details on the developers of the PDP-9 here.

Apparently the design of the ROP Control Memory in PDP-9 systems caus