HP9100A wake-up in 2021

[PaoloB]

Today I had enough spare time to test my HP9100A that was idle since about > 5 years.
I expected that a long storage time could result in a faulty unit so I was ready to bad news, indeed at power-on there was no display !

Anyway the registers indicator backlight was on so that at least the low voltage power supply was OK. I checked the three fuses first, all ok (the HV one was a bit suspect, like having some accrection along the thin wire but was ok on a ohm-check).
I was suspecting some oxidation of contacts so I gently moved up down the two HV boards around the CRT and the board protruding from the power supply case in the aim to break oxide layers if any.

After these manipulations the next power-on was OK, the three register 0's showed on the display after some 20 seconds: all ok with the CRT and related power supply then.

I went along with a few manual calculations, (sum, multiply, trigs) all ok.
I then input (manually) the 9100A test program (from the service manual), checked it line-by-line via the STEP-PRGM key editing a few mistakes and then run it: all OK, the three registers blinked their correct Z=1. ; Y=2.000 ; X=3. around three seconds.

I then recorded the test program onto a magnetic card.
I erased the RAM program using another magnetic card which fills the whole memory with STOP (code 41).
I used the newly recorded magnetic card to reload the test program and run it: all ok.

As a first conclusion I could say that all the basic functionalities are OK after the long storage, I took a log for these in view of a future re-check when it could happen.

In 2021 this machine is now over 50 years old, I was wondering that it is likely that this was the only HP9100A in function today in the whole world.

I add a few pictures as a record of the feat.

[Jurgen Keller]

Great to hear that your 9100A is still in working condition! Congrats, such a nice and iconic calculator. I don't think it's the only one out there, but it's for sure a quite rare beast.

Do you have any accessories for your 9100 calculator? If you're missing the manual have a look at hp9100.info (BTW, any contributions are always welcome, may it be photos, scanned manuals, or personal stories).

[Massimo Gnerucci]

Congrats Paolo!
And, should you ever think about selling it... we are almost neighbours, I see. ;)

[aurelio]

Congrats Paolo, very nice personal computer, in a very great shape, thank you for sharing the pics a good way to begin the year

[hpcalcuser83]

Beautiful machine! Thanks for sharing! I did not know much about this computer so the web-link is much appreciated.

[lrdheat]

...we had one of these with plotter in one of our high school math classrooms in ~1970\71. Dreamt of having this for my own! Never imagined what would become available in hand held fashion within my lifetime![/align]

[Jlouis]

Congratulations for a 50 years machine still going strong! Are you the original buyer?

(01-03-2021 06:36 PM)lrdheat Wrote:  ...we had one of these with plotter in one of our high school math classrooms in ~1970\71. Dreamt of having this for my own! Never imagined what would become available in hand held fashion within my lifetime![/align]

What a privilege to have classes with such a modern computer at that time! Was it a public school?

Quote:I did not know much about this computer so the web-link is much appreciated.

Enjoy!

[PaoloB]

(01-03-2021 02:24 PM)Jurgen Keller Wrote:  Great to hear that your 9100A is still in working condition! Congrats, such a nice and iconic calculator. I don't think it's the only one out there, but it's for sure a quite rare beast.

Do you have any accessories for your 9100 calculator? If you're missing the manual have a look at hp9100.info (BTW, any contributions are always welcome, may it be photos, scanned manuals, or personal stories).

Hi Jurgen,

I used a bad wording, what I meant to say was that the 9100A I was checking yesterday was (likely) the only one that was powered-up and in use at that moment. I'm aware that there are a few others around that are working fine.
I've no accessories, just copies of service and user manuals and a few magnetic cards, partly self-built using VCR tape on cardboard and three original received from a forum's member.

Thanks for the link, I've been there some years ago but I see now there are many new materials.

[PaoloB]

(01-03-2021 02:51 PM)Massimo Gnerucci Wrote:  Congrats Paolo!
And, should you ever think about selling it... we are almost neighbours, I see.

Hi Massimo,
I'm not planning to sell it any soon, I will preserve it for later studies but I also have in mind to eventually leave it to the "Museo Nazionale della Scienza e della Tecnologia" in Milano to add it to the historical collection.

[PaoloB]

(01-03-2021 07:04 PM)Jlouis Wrote:  Congratulations for a 50 years machine still going strong! Are you the original buyer?

No, I found it as a faulty unit that was going to scrap in a research institute I worked with.
I took it as I liked its "vintage" appearance but without any knowledge of it being a masterpiece of the moon-race era.
The unit was indeed faulty but I managed to identify the fault in a pair of diodes in the power supply so I fixed it and learned its basic use. Much more still to be learned anyway, when I will find time...

Thanks for the video, quite interesting.

(01-03-2021 06:36 PM)lrdheat Wrote:  ...we had one of these with plotter in one of our high school math classrooms in ~1970\71. Dreamt of having this for my own! Never imagined what would become available in hand held fashion within my lifetime![/align]

What a privilege to have classes with such a modern computer at that time! Was it a public school?

Quote:I did not know much about this computer so the web-link is much appreciated.

Enjoy!