HP-41 application module for basic electronics?

[rprosperi]

It may have been the 48, which has some basic EE circuit stuff in the equation solver card, and there were also 304 EE related cards for the 48 from Sparcom.

If that sounds familiar, most of the 48 ROM cards are available (ROM images which you can load in RAM cards) here:

https://mega.nz/folder/c8N0wbzS#lTzpYl9ewyBSuIBjQq9v_w