IRQ




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). The interrupt request level (IRQL) is the priority of an interrupt request.

The easiest way of viewing this information on Microsoft Windows is to use Device Manager or System Information (msinfo32.exe). On Linux, IRQ mappings can be viewed by executing cat /proc/interrupts or procinfo programs.

Interrupt lines are often identified by an index with the format of IRQ followed by a number.

On the Intel 8259 family of PICs there are eight interrupt inputs commonly referred to as IRQ0 through IRQ7.

On x86 based computer systems that use two of these PICs, the combined set of lines are referred to as IRQ0 through IRQ15.

Newer x86 systems integrate an Advanced Programmable Interrupt Controller (APIC) that conforms to the Intel APIC Architecture. These APICs support a programming interface for up to 255 physical hardware IRQ lines per APIC, with a typical system implementing support for only around 24 total hardware lines.

Master PIC
* IRQ 0 — system timer (cannot be changed);
* IRQ 1 — keyboard controller (cannot be changed);
* IRQ 2 — cascaded signals from IRQs 8–15;
* IRQ 3 — serial port controller for COM2 (shared with COM4, if present);
* IRQ 4 — serial port controller for COM1 (shared with COM3, if present);
* IRQ 5 — LPT port 2 or sound card;
* IRQ 6 — floppy disk controller;
* IRQ 7 — LPT port 1 or It is used for printers or for any parallel port if a printer is not present.

Slave PIC
* IRQ 8 — RTC Timer
* IRQ 9 — The Interrupt is left open for the use of peripherals. open interrupt / available or SCSI host adapter;
* IRQ 10 — The Interrupt is left open for the use of peripherals. open interrupt / available or SCSI or NIC;
* IRQ 11 — The Interrupt is left open for the use of peripherals. open interrupt / available or SCSI or NIC;
* IRQ 12 — mouse on PS/2 connector;
* IRQ 13 — math co-processor or integrated floating point unit or inter-processor interrupt (use depends on OS);
* IRQ 14 — primary ATA channel;
* IRQ 15 — secondary ATA channel;

COMPLETE LIST OF X86 INTERRUPTS LINK

Related External Links

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