Dell OptiPlex Gn+, Service Manual

Page: 35 / 139

System Overview 1-23
I
nterrupt Assignments
Table 1-3. Interrupt Assignments
IRQ Line Used By/Available
IRQ0 Generated by system timer.
IRQ1 Generated by keyboard controller to indicate that keyboard’s out-
put buffer is full.
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 serial port 2 (COM2 or COM4) requires service.
IRQ4 Generated by super I/O controller to indicate that the device con-
nected to serial port 1 (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 keyboard controller for each tick of RTC.
IRQ9 Available for use by video controller to indicate that the video cir-
cuitry or monitor requires service.
IRQ10 Available for use by an expansion card.
IRQ11
*
Available for use by a PCI expansion card.
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 interface to
indicate that device requires service. If the EIDE controller is dis-
abled, this line is available for other use.
IRQ15 Generated by device connected to secondary EIDE interface to
indicate 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 PCI IRQ is assigned to another
available IRQ line.