Board ID (Omnibus PDP8)?

From: Rick Bensene <rickb_at_pail.enginet.com>
Date: Tue Apr 20 23:00:06 1999

Tony Wuell wrote, regarding an unidentified OMNIBUS PDP8 Board
>
> There is one DEC board that matches that description - the M837 'Memory
> extension and time share control' (basically the logic to give you a 15
> bit address bus, etc). I've just found the DEC printset, and it uses :
> 7 380 (bus receiver)
> 9 7400
> 5 8881 (bus driver)
> 5 8271 (latches/SR?)
> 3 8235 (AOI gates with common selects)
> 2 8266 (Mux)
> 1 8251 (3->8 decoder)
> 1 74H74
> 1 7474
> 2 7420
> 5 7410
> 3 7404
> 1 74H00
> 5 384 (Bus receivers again, non-inverting)
> 4 314 (7 input NOR gate with odd thresholds)
>
> (54 chips total, I think)
>
This board has many of the same chips, and has 54 chips. I know that there
are more than 1 74H00 on there...I can count at least three on the mystery
board. It *seems* quite similar. Perhaps it is some 'third party'
type of memory 'bank' control similar to the M837?

I'll need to get out a magnifying glass (my old eyes just can't read the
numbers off the chips like I used to be able to), and do a complete chip
inventory on the board.

> >
> > It doesn't seem complex enough to have much functionality, and it's
> > definitely
> > not some kind of I/O board, as there are no ins or outs other than the
> > OMNIBUS.
>
> Could it be a clone of the above DEC board? Is there an M837 in
> the machine
> anywhere?

The mystery board came separate from my PDP8e, which DOES have an
M837 in it, along with 2 8K core stacks, a 3rd 8K worth of solid state
memory, EAE, RK8-E w/3 RK05's, PT8-E w/HS Punched tape reader/punch and
three M8650's.

Curiouser and curiouser...

Rick Bensene
Received on Tue Apr 20 1999 - 23:00:06 BST

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