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Sound card installation
Daniel Baum writes:
> Today, I attempted to recompile my kernel to take advantage of the MS
> Sound System and MPU-401 and something unexpected happened. As the kernel
> booted, it said "IRQ 2 is already in use". /proc/interrupts says it is
> "cascade".
>
> This does not cause any conflicts in Win95 or DOS. Can somebody please
> tell me what "cascade" is and whether it can be moved to another IRQ (or
> something). If this is something everybody is supposed to know from birth,
> please tell me where the documents are and try not to be too abusive.
IRQ 2 is tied to IRQ 9. In an nutshell, there used to be 1 chip for
dealing with IRQs which gave 8 IRQs. They added a 2nd one to the ATs,
and wired it in by connecting it to the 1st one via one of the IRQ
lines. Thus, IRQ 2 is connected to IRQ 9, which I believe what is
meant by "cascade". It might work if you configure it for IRQ 9
instead.
You can cat /proc/interrupts to see which interrupts are in use.
--
Dr. Harvey J. Stein
Berger Financial Research
abel@netvision.net.il
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