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Here is TIPS for PC-AT hardware. Please use this information at your own lisk!
This is a list of IRQ channels in use on standard PC.
| IRQ channel | Function |
|---|---|
| 0 | Timer |
| 1 | Keyboard |
| 2 | (available) (*) |
| 3 | Serial port 2 / 4 |
| 4 | Serial port 1 / 3 |
| 5 | Parallel port 2 or Sound adapter |
| 6 | Floppy Disk Drive |
| 7 | Parallel port 1 |
| 8 | Real Time Clock |
| 9 | (available) (*) |
| 10 | (available) |
| 11 | (available) |
| 12 | PS/2 mouse |
| 13 | Math co-processer |
| 14 | Primary IDE Hard-drive controller |
| 15 | Secondary IDE Hard-drive controller |
(*):IRQ9 is same as IRQ2 on PC-AT (ISA).
This is a list of DMA channels in use on standard PC.
| DMA channel | Functions |
|---|---|
| 0 | (available) (*) |
| 1 | (available) (Sound) |
| 2 | Floppy Disk controller |
| 3 | ECP Parallel port |
| 4 | cascade, DMA controller |
| 5 | (available) (Sound) |
| 6 | (available) (SCSI) |
| 7 | (available) |
(*): Do not use DMA0.
This is a list of ports in use on standard PC.
| device | I/O address | IRQ channel | |
|---|---|---|---|
| Serial port | COM1 | 0x3f8-f | 4 |
| COM2 | 0x2f8-f | 3 | |
| COM3 | 0x3e8-f | 4 | |
| COM4 | 0x2e8-f | 3 | |
| Parallel port | LPT1 | 0x3bc-f | 7 |
| LPT2 | 0x378-f | 5 | |
It is good idea using multi-port card if you want a lot of serial port because the card does not use many IRQs and resources.