Paul Anderson wrote:
You might want to pull the mos memory and get
everything down to one
backplane. I don't know who made the mos, but it might be causing
I've also seen the backplanes and the foam under them cause weird
shorten the bus as much as possible and see if things work better.
Earlier today I did pull the MOS memory, and ran all of my tests, and it
didn't make any difference. It failed the same way, consistently.
I think that I could cram all needed onto one Omnibus, but it'd be
tight...I think that 17 of 20 slots would be full...and I usually like
to have a little room between the boards just to prevent anything from
bumping together. I can't believe that DEC didn't use card guides to
hold the boards in place.
I have not pulled the Omnibus backplanes out of the machine and checked
the foam underneath. Although, the machine does run rock solid in all
This machine is very "original", and hasn't been messed with much at all
since the day it was new other than DEC maintenance during the years it
was in production service.
Maybe I need to do a "housecleaning" on the machine, and pull it apart
and clean everything out. As for the foam, if it has deteriorated, is
it something that needs to be replaced, and if so, what should it be
Thank you for your suggestion to slim down the bus, and see if that
makes a difference. Having less loading on the bus could change timing
of bus signals in such a way that things work...especially in light of
what David Humphries mentioned with regard to a spike in the signal that
clocks the data in the current address counter.