Appendix C. IRQ and DMA Channel Assignments
Appendix C. IRQ and DMA Channel Assignments
The following tables list the IRQ (interrupt request) and DMA (direct memory access) channel assignments
for IntelliStation M Pro computers.
Note: Audio IRQ and DMA resources are required and are assigned by the Plug and Play BIOS or
operating system.
Note: Channels 0–3 can transfer data in 64 KB pages; channels 5–7 can transfer data in 128 KB pages.
Table 53. IRQ Channel Assignments
IRQ System Resource
NMI Critical system error
SMI System management interrupt – power management
0 Reserved, internal timer
1 Reserved, keyboard buffer full
2 Reserved, cascade interrupt from slave PIC
3 Serial port 2 if enabled; otherwise, user available for ISA or PCI bus
4 Serial port 1 if enabled; otherwise, user available for ISA bus
5 Parallel port 2 if enabled; otherwise, user available for ISA or PCI bus
6 Diskette drive controller
7 Parallel port 1 if enabled; otherwise, user available for ISA bus
8 Reserved, real-time clock
9 User available for ISA or PCI bus
10 User available for ISA or PCI bus
11 User available for ISA or PCI bus
12 System board mouse port if enabled; otherwise, user available for ISA or PCI bus
13 Reserved, math coprocessor
14 IDE channel 1 if enabled; otherwise user available for ISA or PCI bus
15 IDE channel 2 if enabled; otherwise user available for ISA or PCI bus
Table 54. DMA Channel Assignments
DMA Channel Data Width System Resource
0 8 bits only User available for ISA bus
1 8 bits only User available for ISA bus
2 8 bits only Reserved, floppy
3 8 bits only Parallel port if ECP; otherwise user available for ISA bus
4 Reserved–cascade channel
5 16 bits only User available for ISA bus
6 16 bits only User available for ISA bus
7 16 bits only User available for ISA bus
58 Copyright IBM Corp. 1997
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