2 IRQ controllers?

[Guest]

Archived from groups: alt.comp.hardware.pc-homebuilt (More info?)

Hi
I am reading that a PC can have 2 IRQ controllers

1) First IRQ Controller
2) Second IRQ Controller

the 2nd one is just connected to the first one in case I need more IRQ
(extended). My question is that the case in the new PCs or this is old
reading? thanks a lot..

 

[Guest]

Archived from groups: alt.comp.hardware.pc-homebuilt (More info?)

esara wrote:
> Hi
> I am reading that a PC can have 2 IRQ controllers
>
> 1) First IRQ Controller
> 2) Second IRQ Controller
>
> the 2nd one is just connected to the first one in case I need more IRQ
> (extended). My question is that the case in the new PCs or this is old
> reading? thanks a lot..


It's been that way for quite a while. IRQ 2 is cascaded with IRQ9,
giving your IRQs through 15.

But modern PCs use APIC, which can give you significantly more IRQs.
http://www.microsoft.com/whdc/system/sysperf/IO-APIC.mspx


-WD