Bug in the HP-41 with R/S and stack lift

[rprosperi]

It's an interesting observation for sure, though I'm curious how you are able to so precisely press [R/S] upon the 9 step (in the original example). I assume the amazingly unlikely ability to do this deliberately, or maybe the more likely chance that this never occurred on a susceptible stack configuration during testing led to it being simply something HP did not encounter.

This behavior being consistent with the manual is IMHO probably a coincidence and while therefor not technically a 'bug' in the classic sense, I would agree that it was not what HP intended.

How on earth did you find this and how many attempts did it take to characterize it?