IRQs and DMA in Win2k

[Kilo Bravo]

Does windows 2000 spoof IRQs? on some machines I see IRQs up to 20. I thought IRQs at the hardware level were numbered 0-15.

Also, why would a hardware device need an IRQ if it also has a DMA channel. For example my floppy disk controller is using IRQ 6 and DMA 2.

--
K.Brown
/*****************************************************************************
To the optimist, the glass is half full.
To the pessimist, the glass is half empty.
To the engineer, the glass is twice as big as it needs to be.
******************************************************************************/

 

[Bob I]

PCI systems have 4 hardware interupt lines(or 8 in some instances)
called A,B,C and D. The CPU has 1 interupt line, so the 1-x IRQs you see
are only a software carryover from the old ISA hardware system.

 

[Rick]

PCI systems have 4 hardware interupt lines(or 8 in some instances)
called A,B,C and D. The CPU has 1 interupt line, so the 1-x IRQs you see
are only a software carryover from the old ISA hardware system.

It's part of the MPS specification. Multi-cpu systems can
have IRQs over 15.

Hardware can use a combination of IRQs, DMA channels,
I/O addresses and memory ranges. It depends on the design
of the hardware.

Rick