Dell Vostro 400, Service Manual, Page: 29 / 118

System Overview 1-17
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
*
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
*
Generated by the integrated audio controller to indicate that it
requires service.
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 the PS/2 mouse to indicate that it requires service.
IRQ13 Generated by math coprocessor to indicate coprocessor error.
IRQ14 Generated by device connected to primary EIDE interface to indi-
cate that device requires service. If no EIDE devices are installed,
this line is available for use by an expansion card.
IRQ15 Generated by device connected to secondary EIDE interface to
indicate that device requires service. If no device is connected to
secondary EIDE interface, IRQ15 is available for use by an
expansion card.
* Default IRQ assignments. These settings may be changed by the system BIOS, the operat-
ing system, or the ICU.