HP48 card PCBs

[DavidG]

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.

[mfleming]

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

[DavidG]

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.

[GreyUser]

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?