Plessey PM-D11/SPC-1 backplane documentation needed

Noel Chiappa jnc at
Fri May 8 14:17:14 CDT 2015

    > From: tony duell

    >> I have a Plessey PM-D11/SPC-1 backplane here

    > How many slots? I assume it's hex height. What (if anything) are the
    > power input connectors?

9; yes; it has the standard 9-pin connector as used on the 11/05-10, and the
early /40s and /45s. (FWLIW, the documentation for the PM-F11 says that _it_
comes with either the same 9-pin connector power harness, or the harness with
the newer 15-/6-pin connector pair, and gives part numbers for each.)

The harness of this one is subtly different, though - instead of all fast-on
tabs at the backplane end, there is a DuPont header on the backplane (looks
like 10 pin), and a bunch of the pins on the large 9-pin connector are
connected to that (not just ACLO and DCLO, but e.g. there are a pair which
are connected to +5V, and another pair to ground (the latter two also go to
fast-on tabs).

    > Is there any reason to assume it's not a clone of a standard DEC
    > backplane ... the 'SPC' part of the name suggests a Unibus peripheral
    > backplane

Oh, I'm sure it's _some_ form of SPC backplane - it has the NPG jumpers from
CA1 to CB1 on all 9 slots, for instance. And it has a bunch of wires running
from 1A/B down to the CDEF part, and then back from CDEF to 9A/B. And the NPG
is routed from 1A down to CA1/CA2, and then back up to 9A.

But I'm trying to figure out exactly what sort of SPC backplane it is. E.g.
it looks like slots 2-8 _might_ be MUD (the signals from 1A/B are bussed
across all those slots on A/B, over to 9A/B). But without documentation, or
a lot of ohm-meter work...


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