Why Does Assigning IRQs Manually Not Work in Windows 2000?Hardware: GPIB>>Plug-in Controllers>>PCI-GPIB
Problem: I have a Windows 2000 system and I am using four PCI devices, one of which is a National Instruments PCI-GPIB device. I was not able to communicate properly and examined the IRQs and found that my GPIB card shared the same IRQ as some other devices in the system. I tried reassigning this IRQ to one that was not used by the devices but it did not fix the issue. What is wrong and how can I fix this problem? Solution: The reason why you are having this problem is probably because you are using an ACPI (Advanced Configuration and Power Interface) compliant system. When you install Windows 2000 on an ACPI compliant system, the operating system will assign an IRQ of 9 to some or all of the devices. This is expected behavior. This is the way in which Windows 2000 takes advantage of all the features of ACPI. IRQ 9 is used by Windows to allow for IRQ Steering which is necessary in order to allow for IRQ sharing. The advantage of doing this is that Windows allows you to add additional devices without generating resource conflicts. Unlike the older versions of Windows, viz., 98 and ME, Windows 2000 cannot rebalance resources. Once the PCI resources are set, they cannot be changed. This is because Windows 2000 is designed to support modern features such as IOAPICs, multiple root PCI buses, multiple-processor systems, and so on while the older operating system do not support them. That said, it would not help to reassign the IRQs manually from the BIOS and will lead to conflicts and errors while using Windows 2000. This is because the new settings are ignored by Windows 2000 during startup as it is already configured based on the settings it was installed on. If you need to reassign IRQs, you will need to reinstall Windows, which will force it to use the new settings. Related Links: KnowledgeBase 0WECRBEO: How Do I Disable the Interrupts (IRQs) on My PCI-GPIB? KnowledgeBase 2F0E9P0Z: IRQ Conflicts with Some ISA Devices and PXI Controllers Attachments:
Report Date: 10/30/2004 Last Updated: 11/01/2004 Document ID: 3ETFO93F |
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