Asus P I-P55SP3AV P/I-P55SP3AV User's manual - Page 14

Feature Guide System IRQs In this manual you'll see something called an "IRQ" mentioned. If you're not familiar with these, this is a short explanation of what they are and why you may need to know about them if you upgrade your system. If you are running Windows 95, your system should, in principle, be able to deal with any IRQ requirements that occur in the process of changing or upgrading your system configuration and you will probably not need to concern yourself with them. Windows 3.x or other users, will need to be aware of IRQ use in the system configuration. An IRQ, or interrupt request, is the process whereby an input or output device tells the CPU to temporarily interrupt whatever it is doing and immediately process something from the source of the interrupt. When finished the CPU goes back to what it was already processing. This happens very quickly. There are 16 IRQs, IRQ 0 through IRQ 15. Devices that need an IRQ line to operate sometimes must have the use of that line exclusively. Some IRQs are already in use by parts of your system. This is a design standard common to IBM-compatible personal computer. Some expansion cards require the use of an IRQ line, for example, network interface cards and sound cards. When you install a card that uses an IRQ, it probably will have a default IRQ setting that you might need to change if that IRQ is already in use and cannot be shared. There are different ways of setting an IRQ assignment in hardware, with jumpers being the most common. "Plug and Play" expansion cards have their IRQ assigned by the system under Windows 95, or, without Windows 95, can be configured using an ISA configuration utility. There is some IRQ setup to do in the BIOS Setup utility. This is explained in detail in Chapter 3.