logic rack?

From: Joe R. <rigdonj_at_cfl.rr.com>
Date: Thu Sep 2 20:46:52 2004

At 06:15 PM 9/2/04 -0700, Bill wrote:
>I have no idea what this is, but it sounds like it's
>made of discrete-transistor logic, and LOTS of it
>Would be a cool find just for all those boards,
>maybe something one could build something really
>old-school out of (like the guy in Pittsburgh who
>built a 4-bit discrete-transitor CPU in 1968 out of
>a lot of scrapped logic boards). It doesn't sound
>like you snagged it, though. :(

   No I didn't :-( I was driving my wife's car and it was WAY too big to
fit in the car. However I told them to save it for me. It's heavy enough
that I don't think the hurricane will bother it since it laying flat on the
ground. I just finished tracing out one of the boards and it appears to be
a NINE-input Diode-Transistor AND gate. Three groups of three diodes with
each group's outputs tied together at the anodes and then each group tied
to the anode of another diode (so now nine diodes driving three diodes).
The cathodes of the three diodes are then tied together and connected to
the base of a single 2N1309 transsitor. (It's now a nine input NAND at
this point). The collector of the first tranistor is connected to the base
of the 2nd 2N1309 transistor. It's output is now a NAND function. I
haven't looked close at the other board but it looks like four buffers (one
transistor driving another one x 4). AKA four Darlington ampliers. The
boards look like new. It's a shame that I'll have to leave them there
through the hurricane. However I am going to call them and tell them again
not to do anything with the rack and to save it for me.


>--- "Joe R." <rigdonj_at_cfl.rr.com> wrote:
>> I got a call from a scrap place today and I made a
>> quick trip out to see
>> what they had before the hurricane hits (it's due to
>> cross DIRECTLY over
>> the place's location so I don't expect the stuff to
>> be there come Sunday AM
>> since most of the stuff is out in the open). Got
>> some DEC core memory so
>> the trip was worth it. One of the things that I
>> found was a "Logic Rack"
>> made by (somebody) Research & (something). Sorry to
>> be vague about the name
>> but I was in a hell of a rush. Anyway it said that
>> they were a division of
>> XEBEC. The rack was ABOUT 8" or 10" thick and ABOUT
>> 32" wide and ABOUT
>> seven foot tall and had HUNDREDS of small circuit
>> cards that plugged into
>> it. None of the ones that I saw had ICs, just glass
>> diodes, trqnsistors and
>> resistors. The cards are 4" long and 2 3/16" wide
>> with a 16 position CINCH
>> contact on one end. The transistors that I looked
>> at were all date coded
>> 1969 but I saw what looked like it might have been a
>> date on the rack that
>> said 1973. Anybody know what this is?
>> Joe
Received on Thu Sep 02 2004 - 20:46:52 BST

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