Autistic HP-65 needs help!

I bought an HP-65 that is showing an odd display, but responds to keypresses. The logic board is fine... operates in another HP-65. That leaves only the two chips on the keyboard circuit board as culprits. Does anyone know which chip to look at, and are these interchangeable with a dead HP-45 or HP-80? Thanks! Mikey


Maybe it can be used as-is to design abattoirs.




That sounded like a reference to Temple Grandin.


Yes. Her. The most famous autistic person i know of, fascinating speaker, and straight thinker. She alone has done more for animals' welfare than PETA will do in a century. I guessed Dr. Mike would have read about her, if only to learn how to get along around here.

BTW: With it's card reader, wouldn't the 65 have been the worlds first NON-autistic pocket calculator?


I heard an interview with Temple Grandin on NPR. She was very interesting. She described going into the cattle chutes to get a cow's eye view and her perceptions were really interesting--the sort that afterwards you think, "of course! why didn't I think of that!"


O.K... I was just trying to have a sequel to my dyslexic/agnostic/insomniac calculator of the past. This 65 computes, but just communicates in an odd fashion that, for now, I don't understand....


HI, Doc;

I do not know the HP65 circuitry, but if you have a display with 'garbage', I'd suspect either the display driver/decoder OR the main ROM contents. As you managed to test the mainboard in another HP65 and it works fine, you are in the right way trying to find the problem in the external circuitry. So, my question would be: the LED display is driven by circuit(s) in the mainboard or somewhere else in the calculator? I have an HP55 but I do not recall how do its internals look like, neither if they remind the HP65's... Anyway, if the LED driver/decoder chips are not in the mainboard, they may also be the cause of it.

The other way to get into a conclusion would be running a pre-recorded program (mag. card) and see it the calculator´s display shows something understandable. I also do not know if the HP65 has the auto-run feature (I know nothing about this dude...), but if it has, that would help a lot.

The closer way to 'see' inside of it was through this picture:

But I did not get too much insight from it.

Sorry not helping the way I would like to...



Can you describe what is wrong with the display? Enter 8 ten times then press EEX and 8 two more times. Do you have:

  • All digits illuminating but are missing the same segment(s)?
  • All segments working but one or more digits are missing?
  • Something totally random every time you press a key?

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