Interview with Dave Cochran from HP Labs

For those interested, here is a 1 hour interview with Dave Cochran
from HP Labs, the designer of HP's first digital voltmeter and the
early calculators including the HP 35. The interview is in honor of
the 35th anniversary of the HP 35.

http://www.viddler.com/explore/sleibson/videos/2/

Dave.

 

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.

http://hpmuseum.net

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

 

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
9100A's.

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.