HP Vectra VL400 - Manual (Page 49)

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4 BIOS Overview
BIOS Addresses
Interrupt Controllers
The Interrupt Requests (IRQ) are numbered sequentially, starting with the master controller, and
followed by the slave.
PCI Interrupt Request Lines
PCI devices generate interrupt requests using up to four PCI interrupt
request lines (INTA#, INTB#, INTC#, and INTD#). PCI interrupts can be
shared; several devices can use the same interrupt. However, optimal system
performance is reached when minimizing the sharing of interrupts.
IRQ
(Interrupt Vector)
Interrupt Request Description
INTR
IRQ0 System Timer
IRQ1 Keyboard Controller
IRQ3 Used by serial port if enabled
IRQ4 Used by serial port if enabled
IRQ5 Free if not used for parallel port or audio
IRQ6 Floppy Disk Controller
IRQ7 LPT1
IRQ8 RTC
IRQ9 Available for PCI devices, if not used by ISA board or USB port
IRQ10 Available for PCI devices, if not used by ISA board or USB port
IRQ11 Available for PCI devices, if not used by ISA board or USB port
IRQ12 Mouse
IRQ13 Co-processor
IRQ14 IDE Primary channel
IRQ15 IDE Secondary channel. Free unless disabled