29 Sep
2003
29 Sep
'03
11:59 a.m.
Anyone have a spare M8191 Unibus Adapter for an 11/84 for sale?
Curt
----- Original Message -----
From: "Tony Duell" <ard(a)p850ug1.demon.co.uk>
To: <cctalk(a)classiccmp.org>
Sent: Sunday, September 28, 2003 1:01 PM
Subject: Re: PDP11/84 continued
Well, with
only the RX211 installed in its original slot, the M9302
terminator properly installed, and G7273's everywhere else, the CPU
still hangs. With G727A cards instead of G7273's, the RX02 will boot an
RT-11 installation floppy.
You are telling me it will work with the single-height grant cards in
slot D, but not with the dual-height ones in C and D?
This is impossible -- the only difference between the 2 types of grant
card is that the dual-height ones also complete the NPG jumper. If it
works with the single-height ones, then the NPG chain must be complete
along the backplane. Adding a second 'jumper' (on the dual height card)
in parallel with the wire-wrapped on on the backplane can't make any
difference.
It sounds like you have backplane problems. Maybe some of the dual-height
cards aren't making proper contact. Maybe the slots you're putting them
in aren't satnadard Unibus slots (unlikely, but...) and the 'extra'
jumper is shorting a couple of signals that it shouldn't...
-tony