irq sharing

[john]

My U.S.Robotics pci modem(win modem) and my onboard cmedia sound both share
irq 19. The sound at times breaks up especially when using modem. Acpi is
enabled and the only way to change according to MS is reload and disable
acpi. There has to be something better than that option. I don't use serial
or parallel or useless floppy drives. The irq's are free and were free when
windows was loaded.Is windows so obstinate that it thinks that I might
someday want these so it keeps them available? How do I tell xp that I will
not EVER install a floppy drive on my system or use the serial ports. 5
irq's are available (no ps2 mouse). Xp creates irq 19 for sound and modem
and 21 for usb. Any workarounds for this? I'll reinstall xp clean if I have
too, just because I have nothing to do for the next 5 hours anyways, but
would really like to see a better approach.

 

[Nick Burns]

As far as your ports, you have to disable your coms and parallel in the bios
before they are free. My cmedia sound uses shared IRQ's with my modem,
network card and USB. I have no sound problems.

 

[john]

I was curios about the sharing and am believe the sound issue is the new
drivers.But still I have the question about the irq's. All the irq's for
serial, parallel and floppy are available. These have been disabled in bios
since I put this machine together. Why does xp have to create virtual irq's
"pardon my french" when it has the legacy/pci irq's to use. My onboard nic
was shuffled to irq 20. I guess the real question here is why bother freeing
up unused resources if xp is going to do it's own thing anyways. And I
appreciate your response Nick

 

[Nick Burns]

As far as your ports, you have to disable your coms and parallel in the bios
before they are free. My cmedia sound uses shared IRQ's with my modem,
network card and USB. I have no sound problems.




I don't know why it does what it does, maybe a MVP will know. Later on.

 

[Alex Nichol]

I was curios about the sharing and am believe the sound issue is the new
drivers.But still I have the question about the irq's. All the irq's for
serial, parallel and floppy are available.

XP supports the APIC (do not confuse with ACPI) Advanced Peripheral
Interrupt Controller, that has been on motherboards for some time. This
allows use of IRQs above 15. At the same time it at last treats IRQs
properly as queues - in which it can return to service another interrupt
as soon as the first has been handed on to the driver concerned. So
they ought to get shared without interference, provided that drivers are
properly written. One way or the other it would appear that the ones
you have are not, and you should look to see if there is an update at
the maker's site