System BIOS
BIOS Addresses
Chapter 3
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The following table shows how the system allocates DMA channels.
Interrupt Controllers
The system’s interrupt controller is equivalent in function to two 82C59 interrupt
controllers. The following table shows how the interrupts are connected to the APIC
controller. The IRQs are numbered sequentially, starting with the master controller and
followed by the slave (both of 82C59 type).
DMA controller
Channel Function
DMA 0 Free
DMA 1 Free if not used for parallel port in Setup
DMA 2 Floppy disk drive controller
DMA 3 Free if not used for parallel port in Setup
DMA 4 Used to cascade DMA channels 0-3
DMA 5 Free
DMA 6 Free
DMA 7 Free
I/O APIC Input IRQ IRQ Description
INTIN0 ICH
INTIN1 IRQ1 Super I/O keyboard controller
INTIN2 IRQ0 ICH system timer
INTIN3 IRQ3 Super I/O - Used by serial port if enabled
INTIN4 IRQ4 Super I/O - Used by serial port if enabled
INTIN5 IRQ5 Free if not used for parallel port or audio
INTIN6 IRQ6 Super I/O - floppy disk controller
INTIN7 IRQ7 Super I/O - LPT1
INTIN8 IRQ8 ICH - RTC
INTIN9 IRQ9 Available for PCI devices
INTIN10 IRQ10 Available for PCI devices
INTIN11 IRQ11 Available for PCI devices
INTIN12 IRQ12 Super I/O - mouse
INTIN13 IRQ13 Coprocessor
INTIN14 IRQ14 ICH - Integrated IDE Controller (primary)
INTIN15 IRQ15 ICH - Integrated IDE Controller (secondary)
INTIN16 PCINTA
INTIN17 PCINTB
