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IRQs
- Thread starter kiv
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pmcmicha
Technical User
- May 25, 2000
- 353
There are not any IRQs above 15 to my knowledge...this is all discussed in the A+ certification. If you have seen this before, could you provide more details as to where and what type of hardware it was being run on? Also what was the OS that was running this hardware?
To do this you would have to take another IRQ slot away to expand out with another 8 for a total of 24 slots....this hasn't been done to my knowledge, unless your talking about virtual IRQs.
To do this you would have to take another IRQ slot away to expand out with another 8 for a total of 24 slots....this hasn't been done to my knowledge, unless your talking about virtual IRQs.
IRQ 15 is generally reserved for the second IDE channel. This is a standard in most PCs today.
A good online reference for computer/networking is the following site. I recommend it strongly.
Gary
gwinn7
A+, N+, I+
A good online reference for computer/networking is the following site. I recommend it strongly.
Gary
gwinn7
A+, N+, I+
- Thread starter
- #4
The IRQs above 15 that i've seen were on a windows XP os,
Hardware specs are p4-2GHz, msi mobo, 80GB hdd, dvd, cdRW,
AGP card.
Im aware of the normal 16 IRQs for A+.
You mentioned something about virtual irqs, could you please explain what are they?
Hardware specs are p4-2GHz, msi mobo, 80GB hdd, dvd, cdRW,
AGP card.
Im aware of the normal 16 IRQs for A+.
You mentioned something about virtual irqs, could you please explain what are they?
pmcmicha
Technical User
- May 25, 2000
- 353
I don't know the complete explanation on this, but I have seen on Win2k and up with too many devices, the OS will share the IRQs for you, but the device doesn't know this, it thinks it has its very own IRQ setting. So on these devices it would show IRQ 16, etc. At least this is how it was explained to me. This article from MS helps explain what I am saying, though it does not say it uses anything above 15...
In Windows, peripheral component interconnect (PCI) devices can share IRQs. In accord with the Plug and Play capability that is defined by the PCI specification, adapters are configured by the computer BIOS and are then examined by the operating system and changed if necessary. It is normal behavior for PCI devices to have IRQs shared among them, especially on Advanced Configuration and Power Interface (ACPI) computers that have Windows ACPI support enabled.
In Windows XP, Device Manager may list some or all of the devices on your ACPI motherboard as using the same IRQ (IRQ 9). (To view the list of resources, click either Resources by type or Resources by connection on the View menu). No option is available to change the IRQ setting. Windows takes advantage of the ACPI features of the motherboard, including advanced PCI sharing. The PCI bus uses IRQ 9 for IRQ steering. This feature lets you add more devices without generating IRQ conflicts.
Note that Windows XP cannot rebalance resources in the same way that Microsoft Windows 98 does. After PCI resources are set, they generally cannot be changed. If you change to an invalid IRQ setting or I/O range for the bus that a device is on, Windows XP cannot compensate by rebalancing the resource that was assigned to that bus.
Windows XP does not have this ability because of the more complex hardware schemas that Windows XP is designed to support. Windows 98 does not have to support IOAPICs, multiple root PCI buses, multiple-processor systems, and so on. When you are dealing with these hardware schemas, rebalancing becomes risky and therefore is not implemented in Windows XP except for very specific scenarios. However, PCI devices are required to be able to share IRQs. In general, the ability to share IRQs does not prevent any hardware from working.
The Plug and Play operating system settings in the computer BIOS do not generally affect how Windows XP handles the hardware. However, Microsoft recommends that you set the Plug and Play operating system setting to No or Disabled in the computer BIOS. For information about viewing or modifying the computer BIOS settings, consult the computer documentation or contact the computer manufacturer.
Manually assigning IRQs to PCI slots in the system BIOS as a troubleshooting method may work on some non-ACPI systems that use a standard PC hardware abstraction layer (HAL), but these settings are ignored by Plug and Play in Windows if ACPI support is enabled. If you need to manually assign IRQ addresses through the BIOS to a device on an ACPI motherboard, you must reinstall Windows to force the installation to use a Standard PC HAL.
Hope that helps.
In Windows, peripheral component interconnect (PCI) devices can share IRQs. In accord with the Plug and Play capability that is defined by the PCI specification, adapters are configured by the computer BIOS and are then examined by the operating system and changed if necessary. It is normal behavior for PCI devices to have IRQs shared among them, especially on Advanced Configuration and Power Interface (ACPI) computers that have Windows ACPI support enabled.
In Windows XP, Device Manager may list some or all of the devices on your ACPI motherboard as using the same IRQ (IRQ 9). (To view the list of resources, click either Resources by type or Resources by connection on the View menu). No option is available to change the IRQ setting. Windows takes advantage of the ACPI features of the motherboard, including advanced PCI sharing. The PCI bus uses IRQ 9 for IRQ steering. This feature lets you add more devices without generating IRQ conflicts.
Note that Windows XP cannot rebalance resources in the same way that Microsoft Windows 98 does. After PCI resources are set, they generally cannot be changed. If you change to an invalid IRQ setting or I/O range for the bus that a device is on, Windows XP cannot compensate by rebalancing the resource that was assigned to that bus.
Windows XP does not have this ability because of the more complex hardware schemas that Windows XP is designed to support. Windows 98 does not have to support IOAPICs, multiple root PCI buses, multiple-processor systems, and so on. When you are dealing with these hardware schemas, rebalancing becomes risky and therefore is not implemented in Windows XP except for very specific scenarios. However, PCI devices are required to be able to share IRQs. In general, the ability to share IRQs does not prevent any hardware from working.
The Plug and Play operating system settings in the computer BIOS do not generally affect how Windows XP handles the hardware. However, Microsoft recommends that you set the Plug and Play operating system setting to No or Disabled in the computer BIOS. For information about viewing or modifying the computer BIOS settings, consult the computer documentation or contact the computer manufacturer.
Manually assigning IRQs to PCI slots in the system BIOS as a troubleshooting method may work on some non-ACPI systems that use a standard PC hardware abstraction layer (HAL), but these settings are ignored by Plug and Play in Windows if ACPI support is enabled. If you need to manually assign IRQ addresses through the BIOS to a device on an ACPI motherboard, you must reinstall Windows to force the installation to use a Standard PC HAL.
Hope that helps.
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