At 11:24 PM -0500 7/30/2000, David A. Gatwood wrote:
>On Sun, 30 Jul 2000, Tony Mantler wrote:
[...]
>> IIRC the F108 should
>> cascade through a slot interrupt on VIA2 (slot E I think, but I could be
>
>Via2 Port B, slot F as far as I can tell.  Slot E is the PDS slot.  Slot
>interrupts then cascade into Bit 1 on Via2 IFR.

Ohyeah, forgot the PDS slot is on E.


>> wrong), meaning that if you miss ANY slot interrupt, they'll ALL be gone
>> forever.
>
>That's the thing, though.  We never get any slot interrupts -- not even
>the first one.  They never make it to VIA2 IFR.  VIA2 reads 0x00 at every
>interrupt, indicating that nothing is ever reaching it.  I don't believe
>it's even reaching VIA2 portB, either, sicne I see to recall that never
>changing values.

Make sure VIA2 portB is *absolutely empty* when the interrupts dissapear
(or never appear in the first place) or you've found your problem. To
narrow things down, I'd reccomend ripping out any Comslot or PDS cards, and
making sure the video interrupts are switched off (Valkyrie, right? I think
that one's fairly well understood how to switch off).


[...]
>> I'd say check to make sure your slot ints aren't being hosed, (ie: make
>> sure you're never leaving the slot interrupt handler with any slot ints
>> still asserted) and you should be most of the way to getting all your
>> interrupts.
>
>Yeah, but as far as I can tell, portB (where the slot ints come in) is
>read-only, i.e. the interrupts get cleared elsewhere.  Am I
>misinterpreting that?  If so, then I probably need to init Port B in some
>way.  Any idea what the magic value is?

Yes, it's read only. The magic mojo to reset it is pretty much going around
to every possible device that could ever be connected via a slot interrupt
and telling them "shut up, I'm trying to get some interrupts here" in an
individually device-specific and entirely obsfucated and undocumented
manner.

As you might be able to tell by now, slot interrupts really suck very large
interstellar rocks. Soon you too will learn to hate Jean Louise Gasse=E9 for
making the Mac II so damn stupid, and everyone after for dragging the
architecture forward so long. And people wonder why I don't want to buy a
Be.

=2E..Not that I'm bitter or anything... Really... ;)


Cheers - Tony :)


--
Tony Mantler       Renaissance Nerd Extraordinaire     nicoya@apia.dhs.org
Winnipeg, Manitoba, Canada                     http://nicoya.feline.pp.se/