HP Vectra XU5 Reference Manual page 55

Interrupt Controllers
The system has two 8259A compatible interrupt controllers. They are arranged as a master
interrupt controller and a slave that is cascaded through the master.
The following table shows how the master and slave controllers are connected. The Interrupt
Requests (IRQ) are numbered sequentially, starting with the master controller and followed
by the slave.
8259A Master to Slave Connections
IRQ (Interrupt Vector)
IRQ0(08h)
IRQ1(09h)
IRQ2(0Ah) SlaveIRQ
IRQ8(70h)
IRQ9(71h)
IRQ10(72h)
IRQ11(73h)
IRQ12(74h)
IRQ13(75h)
IRQ14(76h)
IRQ15(77h)
IRQ3(0Bh)
IRQ4(0Ch)
IRQ5(0Dh)
IRQ6(0Eh)
IRQ7(0Fh)
IRQ12 can be made available by disabling the computer's mouse interrupt using the
ROM-based Setup program.
IRQ3 can be made available by disabling the computer's serial port 1 using the ROM-
based Setup program.
IRQ4 can be made available by disabling the computer's serial port 1 using the ROM-
based Setup program.
IRQ7 can be made available by disabling the computer's parallel port 1 using the ROM-
based Setup program.
Vectra XU Technical Reference
Interrupt Request Description
System Timer
Keyboard Controller
Cascade connection from INTC2 (Interrupt Controller 2)
Real Time Clock
Available for accessory board (ISA/PCI)
Available for accessory board (ISA/PCI)
Available for accessory board (ISA/PCI)
Mouse
PENTIUM
IDE
Available for accessory board (ISA/PCI)
Serial port 2
Serial port 1
Available for accessory board (ISA/PCI)
Flexible Disk Controller
Parallel Port 1
Summary of the HP BIOS 55