Do PCs have more IRQs than before?

[Body]

It used to have 16 IRQs. My P4 XP box has IRQs above 15. When did
this happen?

IRQ Usage Summary:
(ISA) 0 System timer
(ISA) 1 Standard 101/102-Key or Microsoft Natural PS/2 Keyboard
(ISA) 3 Communications Port (COM2)
(ISA) 4 Communications Port (COM1)
(ISA) 6 Standard floppy disk controller
(ISA) 8 System CMOS/real time clock
(ISA) 9 Microsoft ACPI-Compliant System
(PCI) 10 Intel(R) 82801EB SMBus Controller - 24D3
(ISA) 13 Numeric data processor
(ISA) 14 Primary IDE Channel
(ISA) 15 Secondary IDE Channel
(PCI) 16 ALL-IN-WONDER RADEON 8500DV
(PCI) 16 OHCI Compliant IEEE 1394 Host Controller
(PCI) 16 Intel(R) 82801EB USB Universal Host Controller - 24D2
(PCI) 16 Intel(R) 82801EB USB Universal Host Controller - 24DE
(PCI) 17 SoundMAX Integrated Digital Audio
(PCI) 18 Intel(R) 82801EB USB Universal Host Controller - 24D7
(PCI) 19 Intel(R) 82801EB USB Universal Host Controller - 24D4
(PCI) 20 VIA OHCI Compliant IEEE 1394 Host Controller
(PCI) 21 Lucent Win Modem
(PCI) 22 3Com Gigabit LOM (3C940)
(PCI) 23 Intel(R) 82801EB USB2 Enhanced Host Controller - 24DD
(PCI) 23 VIA VT6410 IDE RAID Controller

 

[Body]

It used to have 16 IRQs. My P4 XP box has IRQs above 15. When did
this happen?

IRQ Usage Summary:
(ISA) 0 System timer
(ISA) 1 Standard 101/102-Key or Microsoft Natural PS/2 Keyboard
(ISA) 3 Communications Port (COM2)
(ISA) 4 Communications Port (COM1)
(ISA) 6 Standard floppy disk controller
(ISA) 8 System CMOS/real time clock
(ISA) 9 Microsoft ACPI-Compliant System
(PCI) 10 Intel(R) 82801EB SMBus Controller - 24D3
(ISA) 13 Numeric data processor
(ISA) 14 Primary IDE Channel
(ISA) 15 Secondary IDE Channel
(PCI) 16 ALL-IN-WONDER RADEON 8500DV
(PCI) 16 OHCI Compliant IEEE 1394 Host Controller
(PCI) 16 Intel(R) 82801EB USB Universal Host Controller - 24D2
(PCI) 16 Intel(R) 82801EB USB Universal Host Controller - 24DE
(PCI) 17 SoundMAX Integrated Digital Audio
(PCI) 18 Intel(R) 82801EB USB Universal Host Controller - 24D7
(PCI) 19 Intel(R) 82801EB USB Universal Host Controller - 24D4
(PCI) 20 VIA OHCI Compliant IEEE 1394 Host Controller
(PCI) 21 Lucent Win Modem
(PCI) 22 3Com Gigabit LOM (3C940)
(PCI) 23 Intel(R) 82801EB USB2 Enhanced Host Controller - 24DD
(PCI) 23 VIA VT6410 IDE RAID Controller

To add, you see from the list that IRQ 5 and 7 aren't there. But my
PC does have a HP laser printer attached. And it's working? So how
come neither IRQ 5 or 7 is listed?

 

[Chris Hill]

It used to have 16 IRQs. My P4 XP box has IRQs above 15. When did
this happen?

Happened a couple of years back with the introduction of the APIC.
I'd like to know more as well, but here's one thing I found.
http://www.adriansrojakpot.com/Speed_Demonz/New_BIOS_Guide/APIC_Function.htm

 

[Conor]

It used to have 16 IRQs. My P4 XP box has IRQs above 15. When did
this happen?

Quite a while ago. Do a bit of googling about APIC (Yes, APIC,, not
ACPI - it's not a typo)

 

[JAD]

virtual IRQ's to support sharing

 

[Thomas Wendell]

I think you're using the parallell port in ECP -mode, so it doesn't use an
interrupt, only a DMA channel


--
Tumppi
=================================
Most learned on these newsgroups
Helsinki, FINLAND
(translations from/to FI not always accurate
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[Tom Del Rosso]

I think you're using the parallell port in ECP -mode, so it doesn't use an
interrupt, only a DMA channel

I don't know (and I'm not asking you to take time to research it for me)
but I wonder how that's possible. Sound cards and floppy and hard drives
need both interrupts and DMA, because when the DMA buffer is full (reading)
or empty (writing) the device generates an interrupt to tell the CPU to
empty or refill the buffer.