Hi, Julius;
to perform the tests in the HP17BII, please locate the [CLR]ON key and the three keys in the first, top row over the [MATH], [MODES] and [PRINTER] keys. Now, with the calculator turned to ON, simultaneously press:
[CLR]ON & the key over [PRINTER] key to start an endless selftest; you should see, at some point:
_____________________
|OK-17B II-x |
|_____________________|
and a copyright notice. The 'x' is the firmware version identifier;
[CLR]ON & the key over [MATH] to interrupt this test;
[CLR]ON & the key over [MODES] key to start an interactive test; then, press [STO] key and you'll see:
_____________________
|KBD |
|_____________________|
now press each key, left to right, on each row, top to bottom, till the [+] key. BTW, each key pressed returns a short beep. If everything goes right, you should see:
_____________________
|KBD OK | |
|___________|_________|
Then you press [CLR]ON & the key over [MATH] to interrupt this test.
Hope this helps. (I don't know the HP91, sorry.)
Cheers.
Luiz (Brazil)
Edited: 17 Dec 2004, 11:28 a.m.