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96 Troubleshooting Your System
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.
Troubleshooting External Connections
Loose or improperly connected cables are the most likely source of problems for the system, monitor, and
other peripherals (such as a printer, keyboard, mouse, or other external device). Ensure that all external
cables are securely attached to the external connectors on your system. See Figure 1-2 for the back-panel
connectors on your system.
Troubleshooting the Video Subsystem
Problem
• Monitor is not working properly.
• Video memory is faulty.
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 (COM1 and COM3)
IRQ5 Parallel port
IRQ6 Diskette drive controller
IRQ7 Reserved
IRQ8 Real-time clock
IRQ9 ACPI functions (used for power management)
IRQ10 Available
IRQ11 Available
IRQ12 Mouse
IRQ13 Math coprocessor
IRQ14 IDE CD drive controller (available if disabled in System Setup program)
IRQ15 Reserved (available if IDE CD controller is disabled in System Setup program)
book.book Page 96 Monday, June 5, 2006 1:51 PM