PDP11/84 continued

From: Curt vendel <curt_at_atarimuseum.com>
Date: Mon Sep 29 11:59:48 2003

Anyone have a spare M8191 Unibus Adapter for an 11/84 for sale?


----- Original Message -----
From: "Tony Duell" <ard_at_p850ug1.demon.co.uk>
To: <cctalk_at_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
Received on Mon Sep 29 2003 - 11:59:48 BST

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