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
IRQ | Status | Assignment |
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0 | Used | Timer |
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1 | Used | Keyboard |
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2 | Used | Second 8259 |
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3 | Used | COM2 |
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4 | Used | COM1 |
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5 | Used | COM3 |
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6 | Used | Floppy Disk |
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7 | Used | LPT1 |
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8 | Used | RTC |
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9 | Used | LPT2 orAudio |
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10 | Used | COM4 |
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11 | Used | LAN Adapter (on board) |
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12 | Used | PS/2 Mouse |
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13 | Used | Coprocessor |
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14 | Used | Hard Disk (IDE 1) |
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15 | Used | Reserved (IDE 2) |
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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.
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