HP 41(CX) - ADDING MEMORY

[mfleming]

One limitation to interfacing to the HP41 bus, particularly for an Arduino, is the 6 Volt (I measure around 6.3V) operating voltage. Only a few PIC processors are rated 7V max. You could use level translators as Monte did with the 41CL or resistive dividers as he did with his fpga module.

That's a lot to squeeze into a little module housing, which makes Diego's Clonix/NoV implementations all the more amazing. You would probably want to start by making a breakout cable from an old memory module so you could work at the breadboard level.