Hi, I've got an HP-21 that is missing the battery pack. Does anyone know
which pin is plus and which minus when you look at the calculator from the
back, with the AC adapter plug facing up? I can probably synthesize a
battery pack with a couple of AA NiCd cells but wouldn't want to hook it up
backwards.
There are two contacts at the "back" of the battery box for the cells and
it would be useful to know this info ...
--Chuck