Appendix D. Interrupt request and direct memory accesschannel assignmentsThe following tables list the IRQ and DMA channel assignments.Table 4. IRQ channel assignmentsIRQ System resourceNMI Critical system errorSMI System-management interrupt for power management0 Timer1 Keyboard2 Cascade interrupt from slave PIC3 COM2 (some models only)4 COM15 LPT2/audio (if present)6 Diskette controller7 LPT18 Real-time clock9 Video, ACPI10 MIDI/joystick (some models only)11 Available to user12 Mouse port13 Math coprocessor14 Primary IDE (if present)15 Secondary IDE (if present)Note: The default settings for COM 1 (IRQ 4), COM 2 (IRQ 3), and LPT 1 (IRQ 7)can be changed to another IRQ.Table 5. DMA channel assignmentsDMA channel Data width System resource0 8 bits Open1 8 bits Open2 8 bits Diskette drive3 8 bits Parallel port (for ECP or EPP)4 Reserved (cascade channel)5 16 bits Open6 16 bits Open7 16 bits Open© Copyright IBM Corp. 2001 67
