From: Brian L. Stuart <stuart_at_colossus.mathcs.rhodes.edu>
Date: Tue Apr 21 18:10:32 1998

In message <m0yRkcA-000IyLC_at_p850ug1>, ard_at_p850ug1.demon.co.uk writes:
>> [Depressing to have PDP-6 schematics cause we'll never see one go]
>> Outside of money, what's to keep you from building one from the schematics?
>Well, alas the docs I downloaded show the machine to module level only.
>Now, a module is something like a gate or a flip-flop, so it's possible
>to figure out how the machine worked, but it would be difficult to build
>without schematics of the modules used. Has that manual appeared yet on
>the web?

Well I might be able to help there. I'm not in a position to scan them
and put them on the web at the moment, but I do happen to have a couple
of DEC data books in my collection. One is ca '64 and called System Modules.
It contains 1000, 4000 and 6000 series modules. The other book describes
what are the earliest series of flip-chip modules I've seen. It's dated
2/65 and contains the R, B, W and A series modules. I downloaded the
PDP-6 drawings, but never got them printed satisfactorily, but I seem
to remember reference to the system modules. Could you make a list
of which ones were used on the 6? If so, I'll try to give a description
of each, and if need be, try to dig up a scanner and scan the relevant

>> Nobody says you have to be 100% perfect, I'm sure you could modify here &
>> there to make it usable to normal people...
>> (Like normal power supplies, smaller parts, etc.)
>I must look again... It might be possible to make a modified design
>using TTL. I thought the original PDP6 used some AC (capacitive) coupling
>in at least the carry chain, so you couldn't just copy the schematics
>using TTL chips and expect it to work.

Many of the example circuits in this databook (including both a serial
and a parallel adder) use capacitive coupling. So I expect that these
are likely the same designs used on the early machines.

Brian L. Stuart
Received on Tue Apr 21 1998 - 18:10:32 BST

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