Subject: Re: Utility chip sio's on 4xx (more stories)
To: None <>
From: Michael Smith <>
List: port-hp300
Date: 03/21/1997 14:57:26
Jason Thorpe stands accused of saying:
>  > if all of the IRQ lines on the ISA slot were tied together, so you'd
>  > only need one interrupt input somewhere.
> far as I know, that is how it works... the sio's are probably
> at the top 4 IRQs.

On a 16-bit ISA slot there are about 10 IRQ lines.  If I were
implementing the ISA slot on the 425, I'd wire them all together and
run the single trace off to something with an input that generated an
interrupt.  If that's the Frodo, then that's fine & dandy, but there's
a powerful lot of ASIC crap over by the ISA slot, and it wouldn't
surprise me too much to discover that it's a completely different beast.

Of course, if it _does_ implement ISA properly (ie. provides both
I/O mapped and memory mapped space, as well as busmaster DMA), then there's
no end to the evil things that could be done with it.  8)

>  > Hmm, on the 425 it's at scode 12; still, that implies that it's in
>  > "real" dio space, and should behave like a normal DIO device.  Any
>  > docco for that?
> ...not that I can find.  As far as I know, it was never documented publicly.

*grumble*  Time to go back to reading disassebly.  There should be a law
against selling undocumented hardware.  We even give you the schematics
with our gear 8)

>'s all memory-mapped on the hp300.  We've already dealt with these
> issues... it's called "bus.h" :-)

I'll go read it before I make more of a fool of myself 8)

> ..this is the model attaches the mouse as a logical child of the keyboard.
> It's mainly a place where "mouse" events are collected (for the benefit
> of an X server).


>, more reasons to visit Australia!  :-)  (Off topic, but are you
> near Melbourne?)

Uhh, about 750km by road.

> Jason R. Thorpe                             

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