Nasty Way to Crash a Voyager


In playing around with some of the information talked about in this thread:

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.


Hi Katie!

Very cool discovery. How did you know it is looping, rather than off? When I do your keystroke sequence, the screen goes blank.....

Best regards,



I don't know that's looping for certain, but it's quite likely. I measured the current draw when the display is blanked by this key sequence and it equaled that of when the calculator is running an infinite loop (I tested with a simple LBL-GTO program) about 0.5ma. CMOS doesn't draw significant current when it's not being clocked, and since the calculator doesn't come out of the blank display mode on it's own, it's got to be in some kind of loop.


Just as a side note, your procedure makes my 12C change from END to BEGIN mode and at the end the number 0.40 is in X


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