HP Forums

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.

You can find one example in my github repository here

https://github.com/mafleming/HP48RamCard

A commercial version of a card is discussed in this thread

https://www.hpmuseum.org/forum/thread-17140.html

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.

~Mark

I was thinking mainly of this design:

https://www.hpcalc.org/hp48/pc/pictures/kk2048.jpg

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.

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?