Re: Shared edge triggered interrupts

Meelis Roos (mroos@tartu.cyber.ee)
Fri, 7 Aug 1998 19:01:27 +0300


PTB> Seems a flawed argument to me.

PTB> I don't know how _PC_ interrupts handle themselves, but in an industry
PTB> generic context I would have expected that we now have to return and tell
PTB> X that we handled its interrupt and would it now please stop shouting
PTB> and lower its line (it may have already done so - I don't know if it
PTB> expects an ack).

PTB> We then should look again to see if the interrupt is still asserted, and
PTB> if it is, poll to find out why. I assume the interrupt was latched
PTB> but level triggered, so that resetting the latch while Y is still
PTB> asserting a high will leave the latch set and we'll see it.

To me it seems that you are describing level-triggered interrupts.
These are reliably shareable AFAIK. The problem is with sharing
edge-triggered interrupts.

-- 
Meelis Roos (mroos@tartu.cyber.ee)

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