Repairing HP's 9100B desktop computer/calculator - videos

A just-started series of videos, setting out to repair not one but two 9100B machines and learning about how they work in the process. Here’s the first, a gentle introduction:

It’s an amazing machine, the 9100B. For an overview, see the old calculator museum: Hewlett Packard 9100B Programmable Electronic Calculator

The development of the HP 9100 calculators is an amazing story. Technology author Steve Leibson has done an incredible job of telling this story. For anyone interested in this fascinating read, check out The 9100 Project.

This is the machine which gave rise to Bill Hewlett’s suggestion (or demand!) to make a scientific calculator to fit in a shirt pocket, which of course became the HP35.

This was one of a very few times that I used whatever power I had to pressure Paul and Tom to change their minds about what they wanted to be doing for the next couple of years. I told them that if they were sure we could not do a shirt pocket calculator, then they would have to explain their reasons to Bill Hewlett because I had already told him that we could do it.


I am very excited to see this and will definitely be following. I also have two non-working HP 9100Bs but I am also fortunate enough to have a working HP 9100A. I haven’t looked at them in quite a bit but I definitely did not swap boards from the working one. That remains sealed. I do look forward to the series and wish you the best of luck.

Here is a picture of mine:


That’s fantastic!

I notice more videos have already appeared in the series:


Fantastic. I’ll be checking those out very shortly.

Thank you,

Here’s another one (E #7). The method for drawing a 7-segment display on a x/y CRT is quite interesting.

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