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An IRQ number is automatically assigned to PCI expansion cards after those used by Legacy and PnP ISA cards. In
the PCI Bus design, the BIOS is automatically assigned an IRQ to a PCI slot that has a card in it which requires an IRQ.
To install a PCI card, you need to set the correct "ADSEL" and "INT" (interrupt) assignment. Please refer to "Chapter
2-5" Installing a Riser Card for detail assignments.
IRQ
Status
Assignment
0
Used
Timer
1
Used
Keyboard
2
Used
Second 8259
3
Used
COM2
4
Used
COM1
5
Used
COM3
6
Used
Floppy Disk
7
Used
LPT1
8
Used
RTC
9
Used
LPT2 or Audio
10
Used
COM4
11
Used
LAN Adapter (on board)
12
Used
PS/2 Mouse
13
Used
Coprocessor
14
Used
Hard Disk (IDE 1)
15
Used
Reserved (IDE 2)
2-8. Assigning DMA Channels for ISA Cards
Since ISA cards, both Legacy and PnP may also need to use a DMA (direct memory access) channel, DMA
assignments for this motherboard are handled the same way as the IRQ assignment process described above. You
can select a DMA channel in the PCI and PnP configuration section of the BIOS setup utility. In the BIOS setup, you
should choose "Yes" for those IRQ's and DMA's you wish to reserve for Legacy cards.
