What is an IRQ
Short for Interrupt request, IRQ is a signal that has a direct line to the computer processor, allowing it to stop the processor momentarily and decide what to do next.
Every IBM compatible computer has a maximum of 15 IRQs and are prioritized in the computer according to the importance of the device. The below lists the standard IRQ configuration found in modern PC computers. The below IRQs that have the Card Type 8/16-BIT are configurable and possibly removable.
However, all others cannot be removed or shared. When listing the IRQs and encounter IRQs that are doubled, it could possibly indicate an IRQ confliction or that the IRQ is being shared. The exception to this are IRQs 14 and 15.
| IRQ | DEVICE | I/O PORT | BUS SLOT | CARD TYPE |
| 00 | System Timer | None | NO | NONE |
| 01 | Keyboard | None | NO | NONE |
| 02 | Cascade Controller 2nd PIC | None | NO | NONE |
| 03 | COM 2 and 4 | COM 2: 02F8h (02F8 or 2F8) COM 4: 02E8h (02E8 or 2E8) | YES | 8 or 16-BIT |
| 04 | COM 1 and 3 | COM 1: 03F8h (03F8 or 3F8) COM 3: 03E8h (03E8 or 3E8) | YES | 8 or 16-BIT |
| 05 | Sound Parallel Port 2 | PARALLEL PORT 2: 0278h - 0378h | YES | 8 or 16-BIT |
| 06 | Floppy | 03F0 - 03F5 | YES | 8 or 16-BIT |
| 07 | Parallel Port 1 | 0278h - 0378h | YES | 8 or 16-BIT |
| 08 | Real-time Clock | None | NO | NONE |
| 09 | Redirected IRQ 2 Open Network Available | None | YES | 8 or 16-BIT |
| 10 | Open | None | YES | 8 or 16-BIT |
| 11 | Open SCSI Video | VIDEO: 3B0-3DF | YES | 8 or 16-BIT |
| 12 | Open PS2 | None | YES | 8 or 16-BIT |
| 13 | Coprocessor | None | NO | NONE |
| 14 | Open Primary hard drive (master) Hard Drive Controller | 1ST IDE: 1F0 | YES | 8 or 16-BIT |
| 15 | Open 2nd hard drive (slave) | 2ND IDE: 170 | YES | 8 or 16-BIT |
Read: SDIO
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