Interview with Dave Cochran from HP Labs

I would love to contact any surviving HP calculator designers from that era. I have two dead 9100's that I'll either fix (if I can find schematics) or toss into the dumpster (if I can't.)

John

Try contacting this site for the schematics.

Oh they do have them for download when you use the search feature. Also John does acquire such beasties.

Andrew

Now you are talking calculators! If I was foolish enough to collect anything, I think it would be calculators - and HP35 and HP9100 would be high on my list of ones to start with.

At around $5000 when introduced, I was never going to own a HP9100. Heck at around $400 I was not even going to own a HP35 either, but I did have the chance to spend many, many hours "playing" with both of them.

The 9100 weighed about 16kg but I can assure you it was portable! I helped somebody take one on a small boat to do some survey position calculations. I can still remember the other bloke as he nonchalantly stepped on to the boat with the borrowed 9100 under his arm, and the visions I had of it ending up at the bottom of the harbour. Not to mention the Honda generator we had to take with us to power the thing...

Andy Wood snipped-for-privacy@trap.ozemail.com.au

Have you looked in the HP Journal? I'm 99% sure there is a group of articles about the 9100s, and there will be names of the authors, at least. When did they come out, about '69 or '70?

Cheers, Tom

Are they totally dead? Sometimes it helps to hold a scope probe to a supply rail here or there. That'll show if it's missing somewhere or a cap has dried out. If not completely dead: Check the wire braid core connections. I have seen wire ends corroded away at the solder joints, maybe from flux residue (wasn't HP though). Gear from this era also had large crystals where the innards could fall off if bumped too hard or the silver on there has blackened and lost contact (scope will show missing clock).

Other than that, I am sure the Russians have got the schematics ...

Try hpmuseum.net

There are some schematics and service and operations manuals there.If you want to through it in the dumpster the owner of the website does buy these museum pieces.

Andrew

I have the service manual, but it only includes the power supply and CRT schematics, none of the logic. The only schematic I've seen was reverse-engineered from a 9100B, very cryptic, and I have a couple of

The HP archivist claims that she has all the schematics and, no, we can't see them.

These aren't museum pieces to me. These are very cool but broken calculators I want to fix and use. There has *never* been a calculator that is as nice to use as a 9100.

John

Have you probed around in there to see if the vital signs are present? From my teenage days of buying at ham fests and repairing stuff I remember that most faults are remarkably simple. A broken trace, a bad relay, a burnt out diode in the PS, that sort of thing.