Electronic Calculators
Schematics for HP-9100


From: John Larkin
Subject: HP-9100
Date: January 21, 1998

I have two vintage (ca 1968) non-working Hewlett-Packard 9100 desktop scientific calculators that I would like to restore. I have also found that there are a number of other people around the country with the same problem. Several contacts at HP have told me that HP has DESTROYED the schematics and documentation on the 9100. This machine was a beautiful and audacious engineering tour de force and it would be tragic if all these broken machines had to be junked and, indeed, if the schematics - historical in their own right - are truly lost. I am contacting anyone I can find who might have an interest in the history of calculating and computing, with the hope that someone somewhere (perhaps a retired HP employee?) may have 9100 docs stashed somewhere.

If any such exist, I would like to reproduce them and disseminate copies to the people I know who want to restore their machines.

(Why is it that engineers seem to have so little regard for their own history?)

If you can help, or suggest any further leads to investigate, it would be greatly appreciated.


John Larkin
Highland Technology, Inc
320 Judah St San Francisco 94122
800 473-4418

From: Russ Miller
Subject: HP-9100 Documentation
Date: January 22, 1998

Check out HP's site manual listing site: http://www.tmo.hp.com/tmo/Db/manual/

I received a 9100A/B service manual from HP a few months ago. P/N 09100-90034. It covers trouble shooting, power supplies, and video (I think). No repair information for logic circuits (They say unplug and return to factory for repair), but the troubleshooting section may help localize the problem. Email me if you have specific questions.

From: Nicholas Bodley
Subject: HP-9100 Documentation
Date: January 24, 1998

I have a book published maybe 15-20 years ago, perhaps a "source-book of computer architecture". Iirc, it has some fairly-detailed explanations of the 9100's internal architecture. Hope I can find that book! Also, issues of the H-P Journal of that period (late 1960s?) had article(s) about the 9100. Granted, these are not schematics...

There's an H-P employee on comp.sys.hp48 who posts now and then; also, try to g.i.t.w. James Donnelly, another H-P employee, who has worked on several H-P handhelds and (I think) derivative desktops.

See also the FAQ files associated with sci.electronics.repair for advice on troubleshooting; very good. Maybe you could interest Sam Goldwasser in the process of getting them going (after reading the FAQ!!!). Nice fellow, interested in calcs.

You might try posting a "schematics wanted" message in sci.electronics.repair, but do put "HP9100" in the message title, because (last time I looked) there was a lot of traffic!

Don't all jump at once; I trust people on this List are relatively civilized.

I well understand your pain. I was a Navy fire control tech. in the 1960s, and the incredible Mk.1A mechanical analog fire control computer seems destined for near-total oblivion. Made largely of aluminum, it weighed 3,300 lbs. I would dearly love to get a copy of the mechanical schematic!

Best of luck! These 9100s were quite remarkable.

From: Ulrich Staudt
Subject: schematics of 9100
Date: January 25, 1998

Those HP people tend to destroy papers of devices they donīt support any more...

What I have, is the service manual of the 9120 printer belonging to the 9100. Of course there are also no schematics (except the power supply), but there is a parts list and a lot of drawings how to dissassemble the printer and some adjustment procedures (for instance to align the print head).

If anyone is interested I can make a copy.

Regards Ulrich Staudt (Germany)

From: Alex Knight
Subject: HP9100 schematics
Date: January 26, 1998

While not a complete schematic by any means, there is useful information on the HP9100 contained in the US Patent granted to HP's Tom Osborne, Patent No. 3,623,156. It has a few block diagrams and some general schematics of several key areas of the design, and some interesting theory of operation information.

Unfortunately, the complete image of the patent is not on-line on IBM's patent server (they do have a text-only abstract of the first page). I will try to scan images of the diagrams to post on my Web page, but this will take some time. The copy I have is probably to fuzzy to run through a OCR program and re-create the text. But, if you have access to a local Patent Office you may be able to get a good copy, or order one from the places that sell them.

Still looking for a 9100 - if I can ever find one then I'd be interested in "reverse-engineering" it using scopes, logic analyzers, etc. and documenting the results on the Web for all to see.


Alex Knight
Calculator Technology Archive
From: Ulrich Staudt
Subject: schematics of 9100
Date: January 27, 1998

> Hi Ulrich, I would be very interested. I have a 9100 that works and a 9120 that doesn't.

> Regards
> David Green

Hi David:

No problem to make a copy, shipping cost is US$10 airmail or $5 surface. Please send to

Ulrich Staudt
Louis-Ferdinand-Str. 50 b
D - 45472 Muelheim / Germany

And donīt forget your address!

Regards ulrich
From: John Larkin
Subject: HP-9100
Date: January 27, 1998


Thanks for the response. Yes, I'm still trying to find schematics, service manuals, and even design documentation (pcb artworks, algorithms, whatever)-- not to just repair my calculators, but also because this stuff is historic and may already be lost.

If you have any 9100 docs, or can lead me to someone who has such (especially a member of the original design team) I'd be unspeakably grateful. Good engineering is art, and every artform has a period where it begins, flourishes, and is then superceded by the next form. The age of the transistor lasted only about 10 years, and produced two masterpieces: the Tektronix 547 oscilloscope and the HP9100 calculator. There are lots of 547's (I have 14) and manuals around, but NO documentation on the 9100.

If you can help, please e-mail me or call anytime.

John Larkin
800 473-4418


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