RadAES, thank you for the HP information.
I have an older model, HP-41CX that just gave up the ghost. The on/off switch shorted out and blew the main circut board, bummer. I have since being using a backup, HP-15c.
Talk about a dinosaur, aye?
Kenneth J Hueston, PEng
Principal
Sturni-Hueston Engineering Inc
Edmonton, Alberta Canada