LZ: Re: _MASKABLE INTERRUPTS_


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LZ: Re: _MASKABLE INTERRUPTS_



On Fri, 6 Jun 1997 13:44:36 -0500 (CDT) Michael Wyman
<wyma0012@tc.umn.edu> writes:
>Once I tried to disable interrupts during the
>powerdown when I programmed SecureIt-85... I
>had one major problem (this was I while ago,
>remember)... The calc wouldn't turn back on!
>
>Maybe it was something in _my_ routine, but I
>think that the ON key is in the class of
>_MASKABLE INTERRUPTS_...

I'm pretty sure that I've read somewhere that the ON key is a
non-maskable interrupt, but I could be wrong.  Well if it is a maskable
interrupt, then that would explain why you can't just turn the calc back
on when it crashes(assuming somehow it masks the ON interrupt and shuts
off), and your code may have actually crashed for some reason rather than
correctly shutting down.

It seems like I remember someone writing that you have to mask all the
maskable interrupts before shutting down the calc, so it remains inactive
or something, but the one non-maskable interrupt, the ON key, remains
active so the calc can be turned back on.  This may be way off, but I
remember something being said about this a while back(maybe a month or
two ago?[or even 3??]).


Sincerely,
The Unibomer

Jared Ivey
Unibomer@Juno.com
Ham Call Sign: KF4BXL
The Unibomer's Shack:
     http://www.geocities.com/SiliconValley/Vista/7342/
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