Dell OptiPlex E1 Service Manual page 19

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IRQ0 Generated by system timer.
IRQ1 Generated by keyboard controller.
IRQ2 Generated internally by interrupt controller to enable IRQ8
through IRQ15.
IRQ3 Generated by super I/O controller to indicate that the device con-
nected to the serial port (COM2 or COM4) requires service.
IRQ4 Generated by super I/O controller to indicate that the device con-
nected to the serial port (COM1 or COM3) requires service.
IRQ5 Available for use by an expansion card.
IRQ6 Generated by super I/O controller to indicate that diskette or tape
drive requires service.
IRQ7 Generated by super I/O controller to indicate that device con-
nected to parallel port requires service.
IRQ8 Generated by RTC alarm event.
IRQ9 Typically used by the video card.
IRQ10 Available for use by an expansion card.
*
IRQ11
NIC/default PCI IRQ.
IRQ12 Generated by keyboard controller to indicate that mouse's output
buffer is full.
IRQ13 Generated by math coprocessor to indicate coprocessor error.
IRQ14 Generated by device connected to primary EIDE port to indicate
that device requires service. If the EIDE controller is disabled,
this line is available for other use.
IRQ15 Generated by device connected to secondary EIDE port to indi-
cate that device requires service. If the EIDE controller is dis-
abled, this line is available for other use.
* If an ISA expansion card is configured for IRQ11, the NIC or PCI IRQ is assigned to
another available IRQ line.
System Overview 1-11