IBM 5100 Restoration in progress

Santo Nucifora santo.nucifora at
Fri Mar 13 18:12:04 CDT 2015

Hi All,

Long time reader, first time poster.

I am in need of some assistance in trying to revive an IBM 5100.  It is a
Basic 32k version that was in rough shape.  You can see pics here:

I've been able to clean it up but when I fire it up I see a single "A" on
screen.  I can't seem to get into any diagnostic modes.  The single "A"
indicates an issue with the F2 Base I/O card.  Some of the ICs do have some
rust on them but I'm wondering if it might be the "bridge connectors"
between the Base I/O and Controller (CPU) card.  Are they directional or
can then be swapped or turned around?  I may have not kept them in the
correct orientation but I don't see any mention in the Maintenance manual.

I, pretty much, need someone who has one to take a picture of the top of
their Base I/O and Controller cards.

Any help is much appreciated.  If someone happens to know a common issue
that would make the "Bring up Program" stop at A, I'd love to hear about it.

Thanks in advance,

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