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Hi all,
Whilst clearing attic space from my parents, I came across an HP75C that had been given to me as a child by my grandfather (who has since passed away).

He was a keen calculator and computer enthusiast and kept his equipment in pristine condition. The unit is still excellent and has sentimental value for me. I have been using it and playing around but have noted that the original batteries are non usable and deteriorated.

What would be everyone's recommendation? My intent is to preserve this as a working piece as well as a potential collector’s item. Would you recommend in investing in getting a working battery pack replacement? If so, having noted several advertisements for providing replacement packs, is there any clear recommendation on this? Please excuse my potential naivety on the subject - I am very new to the HP world.

Hello Chris,

From my perspective you should keep it and replace the dead NiCd AA cells.

You can find more battery information
and here

Now if you want to play with it, I suggest that you connect your HP-75C to HP-IL devices (printer, storage, video, etc).

The least costly would be the to connect the 75 to a PC with the following setup:

a) PIL-Box (HP-IL to USB box from Jean-François Garnier, here)

b) HP-IL cable (needed between the HP-75C and the PIL-Box)

c) USB cable (needed between the PC and the PIL-Box)

d) HP-IL devices simulators (here and here)