HP41.org

I have a HP41C that until recently has been operating without any issues. Recently I have been unable to utilize the "USER" mode of the calculator. When the "USER" button is pressed it appears to have no affect (does not indicate user mode on display). Not sure whether this is a hardware or software issue. All other buttons work properly. I have disassembled the device and internal components look to be in good condition (no corrosion). I have tried to reset the calculator but this did not seem to resolve the issue.

Any suggestions.....

Not as convenient of course, but you can do SF 27 and CF 27. CF 27 could be assigned to a user key, but there wouldn't be any point in assigning SF 27 to one.

Not sure if I exactly follow your suggestion. Not sure what a SF or CF 27 is?

Does this issue sound like a hardware failure or is there a special section of memory where this function is located? Curious if anyone else has experienced a similar issue.

It is a hardware problem, but flag 27 is the user-keyboard flag. SF 27 is just the 41's instruction for "Set Flag 27" (ie, activate user keyboard) and CF 27 is "Clear Flag 27" (ie, de-activate user keyboard).