7 Jun
2005
7 Jun
'05
7:38 a.m.
Subject: Re: [SPAM] - Re: Simulated disk drive for RT-11? - Sending mail serverfound on
relays.ordb.org
From: "Jerome H. Fine" <jhfinexgs2 at compsys.to>
Date: Tue, 07 Jun 2005 10:27:42 -0400
To: General Discussion: On-Topic and Off-Topic Posts <cctalk at
classiccmp.org>
No, I have a few too. I have this thing for aquiring odd systems.
Jerome Fine replies:
As far as I understand, a 22 bit PDP-11/23 and all
PDP-11/73 systems use the same memory as the uVAX-I.
That would seem to indicate that the same backplane
can be used for either CPU in a BA23 box. As for a
uVAX-II, I can remember using the SAME box for BOTH
a PDP-11/73 and a uVAX-II system at least 5 years ago.
There were Q22 and Q18.
The CD side of the indicated backplanes were notably different.
It's my uderstanding the uVAX-1 had a special backplane to
accomodate non-PMI memory and there were some power wiring
differences that were dangerous to AB wired cards.
One BA23 I got has a Q22 with all slot pairs AB/CB wired Q22
in a serpentine pattern.
All three BA23s came from internal to DEC.
Allison
Allison wrote:
On Jun 6 2005, 22:46, Allison wrote:
Note there were differenet backplanes used in the
BA23 those
that were compatable with uVAX-1, those that were uVAX-II
and the microPDP-11. Use the wrong one with the desired CPU
and bad results happen.
I've never seen more than one type of backplane in a BA23, and only one
is listed in my manuals: H9278-A. It's compatible with all of
microPDP-11, uVAX-I and uVAX-II without so much as a jumper change.
Are you thinking of something else?