Got to look at the PDP7

From: Tom Uban <>
Date: Mon Jul 22 13:37:01 2002

It has been a while and I am curious what will or has become of the PDP7 ?


At 07:29 AM 6/15/2002 +0000, you wrote:
>Finally was able to get a look at the PDP 7. I think it qualifies as the find
>of the week, or year, for me.
>I have corresponded with those most interested in it. If interested please
>contact me offlist at
>Pictures at:
>Here is the report;
>I saw the PDP 7. It is a delight. It is too bad the entire Lab could not be
>saved as a museum. The computer was installed in 1965 to run a 5 MEV Van de
>Graff Generator which had been installed in 1964. There is still one
>experiment running in the lab so it is not being shut down yet.
>The PDP 7 was replaced in 1992 with a RIDGE 32. The RIDGE 32 was replaced in
>1999 with a SUN IPX which runs the Van de Graf via a GPIB connection.
>However the PDP7 was not removed or even disconnected. Harlan fired it up,
>tried to load a program off a disk drive, by first running a punch tape.
>Finally got the tape loaded and you could see action in the homemade disk
>drive controller, but nada.
>He was able to key in a simple program via the front switches that ran.
>Classic blinkin lights, wow!
>Evidently it is a Germanium transistor computer. Germanium, not being as
>stable as silicon, needs more love, care and attention to keep it running.
>There are two cabinets of boards and parts including extra core. It
>originally came with 4K of Core but they upgraded it with 4K more for a total
>of 8K.
>It has a 555 DECTAPE drive, a paper tape reader and desk in the central
>cabinet. It is 6 cabinets wide, however these are a narrow double door
>cabinet so the entire computer doesn't seem massive. It is cute! The paper
>tape punch is in the cabinet to the far left with 4K of core underneath.
>Second to the left is the other 4K and the power supplies for the memory. The
>third from the left is the console, desk and paper tape reader. IIRC there
>are three more cabinets to the left, the last two sparsely populated. All the
>cards are singles, early flip chip style.
>It originally came with a KSR 33 Teletype which is long gone. They used an
>ADM terminal in a roll around rack. Above the terminal is a HP1300 display.
>At the top are two DEC floppy drives with the Lab's own homemade disk
>controller. All this should be visible in the pictures.
>There is an entire file cabinet drawer of docs and paper tapes. Several boxes
>of boards and components, as Harlan said, a complete set of spares. he also
>indicated they were familiar with board level repairs and that is what it
>took to keep it running. They inherited lots of tapes from a PDP10 at one
>time, because they could use the same ones. There are several cabinets of
>small tapes.
>It is a classic museum piece.
Received on Mon Jul 22 2002 - 13:37:01 BST

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