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80 Troubleshooting Your System
Checking the Equipment
This section provides troubleshooting procedures for external devices attached to the system, such as the
monitor, keyboard, or mouse. Before you perform any of the procedures, see "Troubleshooting External
Connections" on page 81.
Troubleshooting IRQ Assignment Conflicts
Most PCI devices can share an IRQ with another device, but they cannot use an IRQ simultaneously. To
avoid this type of conflict, see the documentation for each PCI device for specific IRQ requirements.
Table 4-2 lists the IRQ assignments.
Table 4-2. IRQ Assignment Defaults
IRQ Line Assignment
IRQ0 System timer
IRQ1 Keyboard controller
IRQ2 Interrupt controller 1 to enable IRQ8 through IRQ15
IRQ3 Available
IRQ4 Serial port 1 (COM1 and COM3)
IRQ5 Available
IRQ6 Available
IRQ7 Available
IRQ8 Real-time clock
IRQ9 ACPI functions (used for power management)
IRQ10 Available
IRQ11 Available
IRQ12 PS/2 mouse port (available if the mouse is disabled through the System Setup
program)
IRQ13 Math coprocessor
IRQ14 IDE optical drive controller (available if IDE CDROM controller is disabled through
the System Setup program)
IRQ15 Reserved (available if IDE CDROM controller is disabled through the System Setup
program)