KDJ11-B PDP 11/73 getting stuck in Exit standalone mode diag #56
jnc at mercury.lcs.mit.edu
Tue Apr 4 17:35:38 CDT 2017
> From: Glen Slick
> the Q22/Q22 backplane is not good for an 11/83 CPU ... M8190 boards and
> both have PMI signals on the CD half of the CPU board.
So I seem to recall hearing tales of PMI cards emitting smoke when plugged
into a Q/Q/ backplane. That doesn't seem to have happened here:
>> I confirmed the KDJ11-B works fine in a BA23, getting past test 56.
So I wondered if his off-brand backplane didn't have +12V or -12V wired up -
whatever it is that causes the damage. So I compared a list of PMI pins with
a QBUS pinout, trying to see if it was the +12V or 12V that would be the
However, I don't see any PMI pins that conflict? (Well, some of them are
ground, or +5V, but will that harm bus driver TTL?) Here's my list of PMI
Anyone have any idea which pin(s) is the issue, when plugging a PMI card into
a Q/Q slot?
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