Listening to device activity. =)

[D. Sanderson]

When I came home today, I jiggled my mouse and clicked to get PointCast's
screen saver off my screen, and noticed that my headphones, hooked up to
the sound card, were making all kinds of weird musical noises.  PointCast
was doing all kinds of network activity and hard drive accesses (as it
normally does) and my headphones were playing along.

Last night--well, this morning--at about 5am, I was looking at various
descriptions of how Windows 95 handles IRQs when I realized why my sound
card and ethernet card were fighting over one IRQ and wouldn't give it up.
I mindlessly went through my BIOS when I first set up the motherboard and
set something that I now realize I shouldn't have regarding how much
control the operating system can have over IRQs.  (The epiphany came while
I was reading about IRQ Holders for PCI Steering.)  After unsetting it,
Windows 95 fixed my problem and I have sound.

Now my sound card's MIDI device seems to be listening to another device's
I/O and trying to play notes in various instruments based on that data.  
It's not network activity, because it's not doing much right now.
Actually, it's tinking at semi-regular intervals, but it's hard to tell
what's doing that. --oop, and now it's stopped.  It's not hard drive
activity; I'm loading Illustrator and it's still silent...

What's mostly bizarre is that Win95 has juggled its "shared" IRQs rather
weirdly: the MIDI device doesn't use an IRQ of its own, and Win95 claims
that the IO registers are causing no conflict.  The sound card has been
put on IRQ 5 all by itself.  Oddly, my ethernet card seems to be sharing
IRQ 9 with my video card (?!?) with no problems.  Maybe something is (was)
doing stuff it shouldn't have been in the IO registers?  Maybe whatever
was doing that has stopped for good?  Maybe it was PointCast specifically?

Just the fact that it's not raw sound data, but MIDI commands being
rendered as notes played by instruments, makes the result really neato
sounding.  Next time it happens I should tape it or something.  :)

Any ideas as to what's going on here?

_____________________________________________________________________
Dan Sanderson                               dsanders at u.washington.edu
University of Washington      http://students.washington.edu/dsanders