Walter wrote: ↑Sun Jul 24, 2022 12:41 pm
Hmmmh, frantically pressing something does neither look like science nor engineering to me.
I recommend trying it, Walter. If it does work for you, that'd be three-for-three locked-up DM42s revived by the same process: and that
is science--doing experiments to test a hypothesis.
If this does prove to be a reproducible process, then it could be the first step in gaining an engineering understanding of what is going on:
--maybe there's a dual-press key combination that kicks the calculator out of its loop, or
--maybe the fast closing of so many key-press circuits temporarily draws the battery to a lower "brown-out" voltage and that somehow triggers a deeper reset, or
--maybe there's only a very brief window in the locked-up cycle when the calculator can accept new input, or
--maybe if the calculator OS receives too many key inputs too quickly, it can't process them, and the asynchronous interrupts jam on top of each other and interrupt the interrupt-handling loop.
I'm not claiming voodoo fixed my locked-up calculator: I know there's an engineering reason why my mad button pressing worked--I just don't know what that reason is. But if we can establish that the process works reliably, then maybe we can zero in on and refine the instructions.
But in any case, my calculator was in limbo, and I tried everything I could find in the documentation to revive it and nothing worked, but the key mashing did it. (My calculator was connected to a computer at the time with a USB cable, another factor that might--or might not--be important.)