Can you post a description of this box again? I had already deleted the earlier
parts of the conversation. But it stuck in my mind. I hmay have the book on
this box as I think it is the same as the couple I have.
If so, there were two versions of the quad wide backplane. One is A-B-A-B all the
way down. And one is A-B-A-B except for slots 6-7 which have C-D for use with the
two board RL controller.
Please post brand name and any model numbers yo have and I will dig thru my
From: cctalk [cctalk-bounces at classiccmp.org
] on behalf of Noel Chiappa via cctalk
[cctalk at classiccmp.org
Sent: Tuesday, April 4, 2017 6:35 PM
To: cctalk at classiccmp.org
Cc: jnc at mercury.lcs.mit.edu
Subject: Re: KDJ11-B PDP 11/73 getting stuck in Exit standalone mode diag #56
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?