PCMech Forums - View Single Post

Charles · 03-20-2003, 02:35 AM

Not wrong at all.

IRQ's are 1 of 4 System Resources. Memory Addresses, I\O Port Addresses and DMA's(Direct Memory Access) being the other 3.
The classic analogy for IRQ's is "students in a classroom". All students(IRQ's) have their hands up, but the teacher(CPU) can only listen to one at a time according to priorities. Win95B (0SR2) and later support a function known as PCI IRQ steering. For this to work both your BIOS and Windows have to support it. Older system BIOSes and Win95 or 95A do not support this feature. If you have this feature enabled BIOS initially assigns IRQ's to PCI devices. To eliminate conflicts Windows will assign changes when needed. If there are insufficient free IRQ's , IRQ steering allows Windows to assign multiple PCI devices to a single IRQ, therefore enabling all devices to function properly. Without IRQ steering, windows begins to disable devices after it runs out of free IRQ's.

Make a printout of your computers IRQ's, follow reboots advice and confirm IRQ steering is enabled in your BIOS and in your OS (95B or later), especially if you plan to use the other PCIs.

03-20-2003, 02:35 AM	#6
Charles Member (11 bit) Join Date: Jun 2000 Posts: 1,372	Not wrong at all. IRQ's are 1 of 4 System Resources. Memory Addresses, I\O Port Addresses and DMA's(Direct Memory Access) being the other 3. The classic analogy for IRQ's is "students in a classroom". All students(IRQ's) have their hands up, but the teacher(CPU) can only listen to one at a time according to priorities. Win95B (0SR2) and later support a function known as PCI IRQ steering. For this to work both your BIOS and Windows have to support it. Older system BIOSes and Win95 or 95A do not support this feature. If you have this feature enabled BIOS initially assigns IRQ's to PCI devices. To eliminate conflicts Windows will assign changes when needed. If there are insufficient free IRQ's , IRQ steering allows Windows to assign multiple PCI devices to a single IRQ, therefore enabling all devices to function properly. Without IRQ steering, windows begins to disable devices after it runs out of free IRQ's. Make a printout of your computers IRQ's, follow reboots advice and confirm IRQ steering is enabled in your BIOS and in your OS (95B or later), especially if you plan to use the other PCIs.