Re: A85: Interrupt/Usgard-TSR question
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Re: A85: Interrupt/Usgard-TSR question
Jeff Tyrrill wrote:
>
> An interrupt is called every 200th of a second, but what if a TSR takes
> longer than that to finish executing? Will the calculator get in an endless
> loop until the stack overflows, or will an interrupt request be ignored if
> the interrupt routines aren't finished executing?
When an interrupt occurs (mode 0,1 or 2), the interrupt flags IFF 1 and
IFF 2
are cleared (interrupts are disabled). An interrupt handler should end
with
EI \ RETI, because a RETI only won't enable the interrupts again.
In other words, the interrupt counter (or whatever) is disabled when the
interrupts are disabled.
--
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mailto:mja@algonet.se there are so many of them to choose from."
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