74
141876(E)
Appendix C – DMA, IRQ and 1
st
MB Memory
DMA Channel Assignments
Table C–1. DMA Channel Assignments
Channel
Description
0
Available
1
Available
2
Floppy Disk (8-bit transfer)
3
Available
4
Cascade for DMA controller 1
5
Sound
6
Available
7
Available
IRQ Mapping Chart
Table C–2. IRQ Mapping
IRQ0
System Timer
IRQ8
RTC Clock
IRQ1
Keyboard
IRQ9
USB
LAN
IRQ2
Cascade to IRQ
Controller
IRQ10
Touchscreen (COM3)
IRQ3
(COM2)
IRQ11
(COM4)
IRQ4
(COM1)
IRQ12
PS/2 Mouse
IRQ5
Sound (LPT2)
IRQ13
FPU
IRQ6
FDC
IRQ14
Primary IDE
IRQ7
LPT1
IRQ15
Secondary IDE
Note
All IRQs have been assigned to the listed devices, so if you want to add any
additional device interface, you must free the unused IRQ first. For example, if
you don’t use USB K/B or Mouse, then IRQ10 may be set free.