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System Overview 1-17
Interrupt 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
and
IRQ4
Generated by super I/O controller to indicate that device con-
nected to corresponding serial port requires service (IRQ3 for
COM2 or COM4; IRQ4 for COM1 or COM3).
IRQ5 Available for use by expansion card unless this IRQ line is used
by secondary parallel port.
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 expansion card.
IRQ10 Available for use by expansion card.
IRQ11 Available for use by 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 Available for use.
IRQ15 Available for use.