KnowledgeBase
When configuring boards for Your PC You must remember to use only valid IRQ's. What is valid or not depends on what other boars are in Your machine. Some IRQ's are reserved for system use and is used by the motherboard itself.
| IRQ0 | System timer | Not present in bus |
| IRQ1 | Keyboard controller | Not present in bus |
| IRQ2 | Available | Present on 8-bit bus |
| IRQ3 | COM2: | Present on 8-bit bus |
| IRQ4 | COM1: | Present on 8-bit bus |
| IRQ5 | Hard disk controller | Present on 8-bit bus |
| IRQ6 | Floppy controller | Present on 8-bit bus |
| IRQ7 | Printer (LPT1:) | Present on 8-bit bus |
| IRQ0 | System timer | Not present in bus |
| IRQ1 | Keyboard controller | Not present in bus |
| IRQ2 | Secondary IRQ controller | Not present in bus |
| IRQ8 | Real time clock | Not present in bus |
| IRQ9 | Available (appears as IRQ2) | Present in 8/16-bit bus |
| IRQ10 | Available | Present in 16-bit bus |
| IRQ11 | Available | Present in 16-bit bus |
| IRQ12 | Motherboar Mouse Port (PS/2 style)/Available | Present in 16-bit bus |
| IRQ13 | Math Coprocessor | Not present in bus |
| IRQ14 | Primary IDE | Present in 16-bit bus |
| IRQ15 | Secondary IDE/ Available | Present in 16-bit bus |
| IRQ3 | COM2: | Present on 8/16-bit bus |
| IRQ4 | COM1: | Present on 8/16-bit bus |
| IRQ5 | Sound/Parallel port 2 (LPT2:) | Present on 8/16-bit bus |
| IRQ6 | Floppy controller | Present on 8/16-bit bus |
| IRQ7 | Parallel port 1 (LPT1:) | Present on 8/16-bit bus |