[请教]BIOS地址映射?

暴雪

原512K的ROM，现换了一个1M的ROM，windows下在 0xFFF0 0000~0xFFF7 FFFF 可以看到追加的512K的内容。
但在启动计算机时(BIOS没有初始化计算机），无法访问追加的512K的ROM。
  @/ a  Q  O5 \. u* Q+ e5 K+ I. S(可以访问原512K的ROM 0xFFF8 0000~0xFFFF FFFF)
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9 [: u7 _4 Z( P/ p我的计算机用的是intel的ICH7南桥。
在手册上
0 m1 g2 T- @2 I+ f8 W7 K, pFWH_SEL2—Firmware Hub Select 2 Register (LPC I/F—D31:F0)
2 k: k& N2 I+ I: C$ \' WFWH_70_IDSEL — R/W. IDSEL for two, 1-M Firmware Hub memory ranges.
The IDSEL programmed in this field addresses the following memory ranges:
9 K, r. ^. X2 F% C4 KFF70 0000h – FF7F FFFFh
0 f7 J; ?1 ?$ |, S9 wFF30 0000h – FF3F FFFFh
, ?1 }2 ?; K6 u: G+ D: h在这里 IDSEL 如何理解。
FWH_DEC_EN1—Firmware Hub Decode Enable Register
(LPC I/F—D31:F0)
FWH_70_EN — R/W. Enables decoding two 1-M Firmware Hub memory ranges.
! \5 Y" A+ K; h/ h- v0 = Disable.
3 n7 ?" }* A  ]1 G  m3 ^$ T! T1 = Enable the following ranges for the Firmware Hub
FF70 0000h – FF7F FFFFh
FF30 0000h – FF3F FFFFh
除了上面的数据区域，还有其它的数据区域控制ROM到内存地址的映射吗？
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谢谢大家了！！！

xtdumpling

IDSEL是LPC spec的一个信号(Device Select),
This one clock field is used to indicate which of multiple Firmware components is being selected.
The four bits transmitted over AD[3:0] during this clock are compared with values strapped onto
1 ~# p; C8 O1 u/ w# Opins on the Firmware component. If there is a match, the Firmware component will continue to
decode the cycle to determine which bytes are requested on a read or which bytes to update on a
write. If there isn’t a match, the Firmware component may discard the rest of the cycle and go into
  r& h+ [# C. t1 O! fa standby power state.

详见LPC spec:
http://www.intel.com/design/chipsets/industry/25128901.pdf
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) z7 T: t, _* n: b在ICH 7 中似乎就这几个吧(FWH_SEL1,FWH_SEL2,FWH_DEC_EN1,BIOS_CNTL),据我现在知道的.