Affected System Resources and Addresses
Table 1 lists the system resources and associated I/O addresses that should not be directly accessed by BIOS AML code (the "blocked ports" list).
Table 1 Blocked I/O Port Addresses and System Board Resources
|
0x000 0x00F
|
DMA Controller 1
|
|
|
0x020 0x021
|
Programmable Interrupt Controller
|
Access is never allowed*
|
|
0x040 0x043
|
System Timer 1
|
|
|
0x048 0x04B
|
Timer 2 Failsafe
|
|
|
0x070 0x071
|
System CMOS, RTC
|
|
|
0x074 0x076
|
Extended CMOS
|
|
|
0x081 0x083
|
DMA1 Page Registers
|
|
|
0x087
|
DMA1 CH0 Low Page
|
|
|
0x089
|
DMA2 CH2 Low Page
|
|
|
0x08A 0x08B
|
DMA2 CH3 Low Page,
|
|
|
0x08F
|
DMA2 Low Page Refresh
|
|
|
0x090 0x091
|
Arbitration Control Port Card Select Feedback
|
|
|
0x093 0x094
|
Reserved System Board Setup
|
|
|
0x096 0x097
|
POS Channel Select
|
|
|
0x0A0 0x0A1
|
Cascaded Programmable Interrupt Controller
|
Access is never allowed*
|
|
0x0C0 0x0DF
|
ISA DMA
|
|
|
0x4D0 0x4D1
|
PIC Edge/Level Control Registers
|
Access is never allowed*
|
|
0xCF8 0xD00
|
PCI Configuration Space Access
|
|
*Read or write accesses to these ports are always blocked, regardless of the BIOS use of the _OSI method.
posted on 2007-03-12 17:23
yuhen 阅读(1090)
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