VAX 11/780 progress ... just a little

From: Johnny Billquist <>
Date: Thu Sep 25 05:14:13 2003

On Wed, 24 Sep 2003, Gunther Schadow wrote:

> Hi, I'm still wondering if I'm left the only one actively messing
> around with a VAX 11/780, because all the help I get comes
> from PDP-11 people ... but that's adequate since I am still
> debugging the UNIBUS.

Well, I don't have any 11/780, but I do run an 11/790. :-)
But I'm also PDP-11 people, I guess...

To make a short answer: the unibus termination is *vital*.
If you fail diagnostics with it inserted, it's not because of the
termination, but because some problem in your Unibus don't show up
otherwise. The termination should be in the last slot, in AB.

Then you should check the NPR-line all the way through the Unibus. Unless
you have a card that uses DMA, or have the pins bridged, you should have
the wire installed in the Unibus. All slots not occupied by something
should have a Unibus grant card inserted in C.


Johnny Billquist || "I'm on a bus
                                  || on a psychedelic trip
email: || Reading murder books
pdp is alive! || tryin' to stay hip" - B. Idol
Received on Thu Sep 25 2003 - 05:14:13 BST

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