IRQ definition
Below is a list of the IRQ numbers on the system
IRQ 0 | System timer | This is reserved for the internal system timer. This is not available to peripherals or other devices. |
IRQ 1 | Keyboard | Reserved for the keyboard controller. This interrupt is exclusively for keyboard input. |
IRQ 2 | Cascade interrupt for IRQs 8-15 | This interrupt cascades the second interrupt controller to the first. |
IRQ 3 | Second serial port (COM2) | The interrupt for the second serial port and often the default interrupt for the fourth serial port (COM4). |
IRQ 4 | First serial port (COM1) | This interrupt is normally used for the first serial port. On devices that do not use a PS/2 mouse, this interrupt is almost always used by the serial mouse. This is also the default interrupt for the third serial port (COM3). |
IRQ 5 | Sound card | This interrupt is the first choice that most sound cards make when looking for an IRQ setting. |
IRQ 6 | Floppy disk controller | This interrupt is reserved for the floppy disk controller. |
IRQ 7 | First parallel port | This interrupt is normally reserved for the use of the printer. If a printer is not being used, this interrupt can be used for other devices that use parallel ports. |
IRQ 8 | Real-time clock | This interrupt is reserved for the system's real-time clock timer and can not be used for any other purpose. |
IRQ 9 | Open interrupt | This interrupt is typically left open on devices for the use of peripherals. |
IRQ 10 | Open interrupt | This interrupt is typically left open on devices for the use of peripherals. |
IRQ 11 | Open interrupt | This interrupt is typically left open on devices for the use of peripherals. |
IRQ 12 | PS/2 mouse | This interrupt is reserved for the PS/2 mouse on machines that use one. If a PS/2 mouse is not used, the interrupt can be used for other peripherals, such as network card. |
IRQ 13 | Floating point unit/coprocessor | This interrupt is reserved for the integrated floating point unit. It is never available to peripherals or other devices as it is used exclusively for internal signaling. |
IRQ 14 | Primary IDE channel | This interrupt is reserved for use by the primary IDE controller. On systems that do not use IDE devices, the IRQ can be used for another purpose. |
IRQ 15 | Secondary IDE channel | This interrupt is reserved for use by the secondary IDE controller. |