In playing around with some of the information talked about in this thread:
http://www.hpmuseum.org/cgi-sys/cgiwrap/hpmuseum/archv014.cgi?read=64172
I stumbled across a nasty way to crash a Voyager -- any of them: 10C, 11C, 12C (at least the original ones), 15C and 16C. On the 16C you need to do this in FLOAT mode.
Here's how:
I'm going to refer to the simultaneous key sequence [ON]+[TOP LEFT KEY] as [ON-TLK] because the keyboard labels are different on each calc.
1) put a 10 in the X-register
2) press [ON] - calc turns off
3) press [ON-TLK] - this rotates the X-register by 22 bits(?)
4) press [ON] - calc turns off
5) press [ON-TLK] - you'll see something like "0.0000 10" (an unnormalized number)
6) press [1/x] - try to take the reciprocal of this number
Your calc will lock up in a tight (battery draining) loop that even an [ON]+[-] won't break out of. The only way that I've found to break this (other than power reset) is to do another [ON-TLK] and turn it back on again. Luckily operation does not destroy the contents of memory, at least not that I've encountered.