What is the side slot on the HP 41CX for?

[Joe Horn]

(09-06-2014 11:57 PM)EdFab Wrote:  On the HP 41CX on the right side, looking at the side, there is a slot. On my calculator, it's empty. What's supposed to go in there?

If you look closely in that port on your 41CX, there are two tiny holes in it that seem to serve no purpose. They are artifacts from the original design for the 41C, which had two spring-loaded gold-plated ball bearings there, which provided an alternate power supply path.



The 41C was made with those contacts for only a little while, because HP soon decided not to produce a matching power supply, and stopped including those ball bearings and springs in all 41's.

Namir: Are you sure that the original 41's came with a rechargeable battery pack? I seem to remember that every 41 came with the standard N-cell holder, and that the NiCad pack was an optional accessory.