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
