help needed: problem with UNIBUS access on my PDP-11/70

From: Gooijen H <GOOI_at_oce.nl>
Date: Mon Jul 15 03:38:00 2002

Reading the replies, not from the screen, but printed, I notice
a comment from Tony. This could be important!

> Of course you might still have an open NPG jumper on the slot
> where the DL11-W is (this card does not short CA1 to CB1).

That's an eye-opener for me! I thought that the DL11 would
short CA1 to CB1. I guess that some cards that do not use DMA
(NPR) short these 2 pins and some *do not*.

Since the machine was originally with a remote console,
(hard lesson: DO take notes on any action you do to a PDP-11,
if you do: make better/more elaborate ones), I think that there
was no DL11 in it, but the Unibus serial remote console M8255
was in slot #40. I swapped the M8255 for an M7856.
Now, if the M8255 *does* bridge/use NPR ...

I will check this evening of course, no matter what pops up!
I will do the other tests anyway, and make notes! They will
be very useful for future reference.

Again, thanks all so far,

- Henk.
Received on Mon Jul 15 2002 - 03:38:00 BST