The elusive negative zero on the HP 30b

[EdS2]

(In a previous thread, it was noted that the final small digit of the version string is the day-of-week, and it comes out different depending on the user's date format settings. The version string itself does not vary in appearance or meaning - it must be interpreted in factory-fresh format.)

Good point about the stack behaviour: we must press Input twice if we want to duplicate a freshly-entered number.

I just tried again and got the negative zero for both -55555 and -33333. Also -32767 so that's another theory falsified. And -16383.