HP2100 core memory problems

From: Mark Green <mark_at_cs.ualberta.ca>
Date: Wed Aug 18 22:21:19 1999

[Charset iso-8859-1 unsupported, filtering to ASCII...]
> Well, once again I come to the well for knowledge.....:) Seeking advice from
> those up on core memory
> Here's the symptoms. The full test of 8K takes about 2 hours (with a cycle
> of 3). On different boards it gets to different locations before the parity
> error halt. So far mostly at the middle or end, I don't recall it ever
> parity halting towards the beginning. I'll get a parity error halt on say
> location 012336 for example. I then manually go to the failing location and
> try storing different values in the location and reading them back out (all
> via the front panel). Most of the time this gives a parity error like you
> would expect. But - many times it doesn't. Then just for kicks I restart the
> diagnostic a few locations lower (like 012320 in this example) than the
> failing location. It fails right away usually (like location 012322), quite
> a few cells before the location which originally failed. This causes me
> great confusion, because it's actually now failing on addresses which
> previously tested OK just a few minutes ago on the previous test pass.

My gut feeling is the problem might not be with the memory board. When
I see sort of random faults of this nature the first thing I think
of is heat and the second is power. You mentioned that you checked
the 20 volt line, but what about the others? Did you check when the
problem was occuring? If its a heat problem, it could be the CPU or
the memory controllers. Have you tried running it with the case open
so there is better air circulation? I hope this gets you started.

By the way, do you know of any good sources for parts/software for
the 2100? I picked up two of them a few weeks ago and I'm in the
process of cleaning them. I used to program 2100s, but that was
25 years ago. I'd like to get mine running so I can show the kids
what I used to use :-).

Dr. Mark Green                                 mark_at_cs.ualberta.ca
Professor                                      (780) 492-4584
Director, Research Institute for Multimedia Systems (RIMS)
Department of Computing Science                (780) 492-1071 (FAX)
University of Alberta, Edmonton, Alberta, T6G 2H1, Canada
Received on Wed Aug 18 1999 - 22:21:19 BST

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