IRQ is called Interrupt Request and the devices use this to get an ID to use processor resources. I would like to quote an example here and that is, when you press a key on your keyboard it sends a signal to the processor via an IRQ channel to let it know that it needs to process some data and in response processor spare some resources to process the request. There can be more than one scenarios where 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 and a modem on COM 3. let me share a list of IRQs;
| IRQ Number | Purpose |
| IRQ0 | System Timer |
| IRQ1 | Keyboard |
| IRQ2 | Cascaded with IRQ 9 |
| IRQ3 | Default COM2 and COM4 |
| IRQ4 | Default COM1 and COM3 |
| IRQ5 | LPT2 |
| IRQ6 | Floppy Drive Controller |
| IRQ7 | LPT1 |
| IRQ8 | Real Time Clock |
| IRQ9 | SEE 2 |
| IRQ10 | Open |
| IRQ11 | Open |
| IRQ12 | PS/2 mouse or Open |
| IRQ13 | Math Coprocessor |
| IRQ14 | Primary Hard Drive controller |
| IRQ15 | Secondary Hard Drive controller |
How to Check IRQ Assignment?
- Go to Start Menu
- Go to My Computer
- Right Click on My Computer
- Go to Manage
- Go to Device Manager
- Click on Device Manager and Go to View Menu and Select Resources By Type
How To Change IRQ Settings
Note: Changing system resources such as IRQ channels can result in your computer not functioning correctly, always make a note of the settings before you change anything so you can restore them back if required.
If you have a conflict and need to change an IRQ setting:
- Right click on the device in the list (see above picture), and then select properties.
- Click the Resources tab.
- Remove the tick from the Use automatic settings option.
- Select a non-conflicting configuration from the pull down box.
- Click OK
