Why don't they make more IRQs?

[pulse8]

It seems like a pretty simple idea, so I'm sure there's a technical reason why no one has made it so that there are more IRQs so that sharing isn't an issue. Anyone know what that is?

Thanks!
David

 

[StanFL]

I'm sure someone will jump in and correct me if I'm wrong but I believe we'd need to ditch the entire x86 instruction set to address more IRQ's. In other words a new processor that would NOT be compatible with the majority of pc hardware and software done in about the last decade and a half. Simple to do eh?

 

[pulse8]

Well, I meant more just the idea of the solution being simple...not the solution itself.

David

 

[Killbat]

Stan's right. It's left over from the 8088/8086 days.
Sheesh.

 

[Nullity]

I've seen server boards with up to 20+ IRQs...I wonder how they did it...

Null

 

[Adul]

I thin you can get up to 32 IRQ's but I don't remember where I read it. Maybe it was refering to dual processor systems.


BTW, Win2k does virtual IRQs.

 

[jeremy806]

What I know (please correct me fellas):

The XT platform had 8 interrupts, 0-7. In order to make the AT platform, 8 more IRQs, 8-15, were added with 2 and 9 being linked together such that 8 additional IRQs are all supported through original IRQ 2. Hence, you always (in a way) share IRQ 9 for the high IRQs, even though some OSes do not report it that way.

Jeremy

 

[chuckieland]

mmm
i wonder how many people are been trouble by the current lack of IRQ problem
i been trouble by it many time

 

[DRGrim]

I say we ditch the x86 instruction set. At the next big breakthrough, such as optical computers, we should invent a new one, and they had damn well better be expandable to stop stuff like this from hapining.
Isnt it the main reason Macs are faster? Because were really useing 15 year old technology?
Anyway, just my thoughts.

 

[Pyro]

"I say we ditch the x86 instruction set"

So I suppose you'll be the first in line to get an Itanic when (or if) it comes out? Face it, legacy may be holding us back a bit, but its needed and you can't just make a change.



Does anyone know if AMD's x86-64 can do anything for IRQs?

 

[AndyHui]

Both WinNT and Win2K can address up to 255 virtual IRQs. This is why everyone sees all their peripherals stuck on something like IRQ9 when Win2K has been installed in ACPI mode. Usually that IRQ with everything on it is used as a gateway to those IRQs above 15, and sometimes, the device manager shows those devices using stuff like IRQ18, IRQ19, etc.

The only problem is that not all hardware likes IRQ sharing or can handle this virtual IRQ stuff, which is why so many people have problems.