Acer Extensa 500 服务手册
18
System Introduction
DMA Channel Assignment
DMA Channel
Function
DRQ0
Audio(optional)
DRQ1
ECP or Audio(optional)
DRQ2
Floppy
DRQ3
ECP(optional)
DRQ4
DMA controller
DRQ5
Not used
DRQ6
Not used
DRQ7
Audio
I/O Address Map
I/O Address
Function
000-00F
DMA controller-1
020-021
Interrupt controller-1
040-043
Timer 1
060, 064
Keyboard controller 8742 chip select
061
System speaker out
040B DMA
controller-1
061
System speaker
070-071
Real-time clock and NMI mask
080-08F
DMA page register
0A0-0A1
Interrupt controller-2
0C0-0DF
DMA controller-2
0F0-0FF
Numeric data processor
120-13F
180-18F
Power management controller
170-177
2nd EIDE device (CD-ROM) select
1F0-1F7
1st EIDE device (hard drive) select
220-22F
Audio
240-24F
Audio(optional)
278-27F
Parallel port 3
2E8-2EF
LT Win modem or COM4(optional)
2F8-2FF
COM2 or LT Win modem(optional)
378, 37A
Parallel port 2