What are IRQ's

[Dharmesh Arora]

I had installed Windows Xp on my system. I would like to know that what are irq's? Can any body knows about it? Kindly provide me the correct information on IRQ's. Would be grateful to you if any provides me the correct information on the above issue.

[Hardwareman]

IRQs are hardware lines over which devices can send interrupt signals to the microprocessor. The easiest way to explain it is that when a device needs the CPU it sends a request along the IRQ to the CPU. When the CPU gets this request the CPU stops everything it is doing and dumps all its current work to cache or to the HDD if you have no RAM left. It then services the device that sent the request. It will then get the work it was doing from cache/HDD and carry on what it was doing before that interrupt was sent. If you get too many IRQ requests or u drop the latency you will increase the chance that the CPU wont have time to process your audio before it is finished servicing the device that sent the interrupt request.

[Maxforu]

IRQ's are hotlines to the main computer (CPU) that allow devices connected to the computer to signal the CPU that they need immediate attention. An IRQ is is really an Interrupt Request line. In the case of expansion boards, it is an actual contact (finger) on the board, and it is a corresponding pin in the sockets on the bus.

[Killen]

IRQ stands for Interrupt ReQuest and refers to special numbered channels that are used by devices to get the processors attention. Whenever a device has a task for the CPU, it sends a signal to the CPU through an IRQ. When the CPU sees the signal, it interrupts its current task and gives it attention to the device. The computing phrase "interrupt request" (or IRQ) is used to refer to either the act of interrupting the bus lines used to signal an interrupt, or the interrupt input lines on a Programmable Interrupt Controller (PIC). Before you buy a new card or device find out whether it needs an IRQ. Interrupt lines are often identified by an index with the format of IRQ followed by a number. IRQ conflicts can occur when new hardware is installed or reconfigured, for example, it can cause problems if you have your mouse on COM 1 (IRQ4) and a modem on COM 3 (IRQ4), below is a list of the default assignments for IRQ channels in Windows XP.