Info wanted: IBM vacuum tube digital computer demonstrator

From: Joe <>
Date: Sun Feb 23 09:21:00 2003

   Does anyone on here know anything about a digital computer demostrator unit made by IBM in the late '50s? It's housed in a nice wooden box about 2 feet wide x 15" deep x 12" tall. On the top of the box is a brass plaque that says "Presented by International Business Machine Corporation". Inside is a grey painted metal box with a row of ten 9-pin tube sockets along the back of top. In front of each socket is a single nean light. In front of that are blocks with small holes for jumper wires similar to those used in the Heathkit trainers. One end of the box has a male Jones plug connector and the other end has a female connector. It looks like the units were made so that additional units could be stacked together. On the front side of the grey box is a tag about 1 1/2" x 3" that says IBM in large letters. In a compartment on the right side of the wood case is a power cable that plugs into one of the Jones plug connectors. Under the grey metal chassis is a compartment with jumper wires, spare neon lamps and o
ther small parts. Along the front edge of the box are two rows of holes that hold modules that plug into the sockets in the metal chassis. Each module is an open chassis about an inch square and 4 to 7 inches tall. Each chassis has at least one vacuum tube in it and some have two tubes, one above the other. Each chassis has a metal hoop or bail that goes up and over the top of the top most tube and back down the other side to form a handle for inserting and removing the chassis. On the top of the bail is a small tag with numbers like "TR-2", etc. Besides the tubes the chassis also have other small components such as resistors and capcitors. There are a total of twenty of the small chassis and each one can be plugged into any of the sockets in the main unit but you have to set a number of jumpers on each socket to a get the correct voltages for each of the tube elements. The tubes can be configured as logic elemements such buffers, invertors, various gates, etc and they jumpered together to form more complex
 such as flip flops. Evidently the nean lamps are used to indicate the state of each logic element. The guy that had it was quite specific and said that is is NOT an analog computer but a digital one. I went through it trying to find a model number or date but could only find the number 56 stamped on some of the tubes. I'm not sure if that's the manufacturering date or not but it's probably close.

   Can anyone tell me more about this thing or even (HOPEFULLY) have a manual for it?

  PS this came from the University of Florida.

Received on Sun Feb 23 2003 - 09:21:00 GMT

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