🚀 go-pugleaf

In article <14327@agate.BERKELEY.EDU> tom@.berkeley.edu () writes:
>
>	I have designed an interface to the MacII using all the APDA info
>that I can get.  It all works great, but with one snag.  I can't get the
>Mac to recognize an interrupt.  I have been able to generate and recieve an
>interrupt from a debounced switch, but from this interface, no success.  My
>suspicion is that the Mac needs a longer pulse, though I am up to 200 nsec.
>and that seems plenty long.  Any ideas?

Bad news I'm afraid ... the answer is 'as long as is required' what you have
to do is design hardware where the software cancels the interrupt. I do
this on all my cards (actually I decode WRITES to my ROMs since noone
uses these - writes to odd addresses cancel pending NuBus interrupts, writes
to even addresses interrupt the onboard processor etc). 

Anyway put a latch for the interrupt that is set by the peripheral that
is requesting it and cleared by some sort of bus traffic, the MacOS handler
you write should generate the required traffic to clear it.

What is happening for you at the moment is that the 68020 is probably taking the
interrupt and polling all the possible sources for it, finding none it just
returns to where it came from.


		Paul Campbell

-- 
Paul Campbell, UniSoft Corp. 6121 Hollis, Emeryville, Ca
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