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HP48 card PCBs - Printable Version

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HP48 card PCBs - DavidG - 12-08-2021 08:58 AM

Some years ago there were hobbyist-produced RAM cards for the HP48 line. I got my hands on one of these and I seem to have lost it. Has anyone ever documented any of these cards? I'd like to see about crafting my own.

RE: HP48 card PCBs - mfleming - 12-08-2021 12:32 PM

You can find one example in my github repository here


A commercial version of a card is discussed in this thread


Somewhere else in the forum is a thread where a member posted a clever solution using a stack of thin PCBs to get a physically correct memory card shell.


RE: HP48 card PCBs - DavidG - 12-08-2021 11:16 PM

I was thinking mainly of this design:


The one I lost is of this design with fewer chips populated.

I think this one (https://www.hpcalc.org/hp48/pc/pictures/stolte20.jpg) is the stacked PCB design.

RE: HP48 card PCBs - GreyUser - 12-15-2021 03:32 AM

I have a 128kb and 512kb card of the stacked board construction shown (actual layout slightly different). It too has the glue logic chips tops sanded/scratched off but I would expect it wouldn’t be too difficult to reverse engineer them.

What info are you looking for? Schematic? Other?