Register Description

R

Extended System BIOS Area (E0000h–EFFFFh)

This 64 KB area is divided into four 16 KB segments that can be assigned with different attributes via PAM control register as defined by the table above.

System BIOS Area (F0000h–FFFFFh)

This area is a single 64 KB segment, which can be assigned with different attributes via PAM control register as defined by the table above.

3.5.22FDHC—Fixed DRAM Hole Control Register (Device 0)

Address Offset:

97h

Default Value:

00h

Access:

R/W

Size:

8 bits

This 8-bit register controls a fixed DRAM hole: 15–16 MB.

Bit

 

Description

 

 

7

Hole Enable (HEN). This bit enables a memory hole in DRAM space. Host cycles matching an

 

enabled hole are passed on to the ICH2 through the hub interface. The hub interface cycles

 

matching an enabled hole will be ignored by the MCH. Note that a selected hole is not re-

 

mapped.

 

0

= Disabled. No hole

 

1

= 15 MB–16 MB (1 MB hole)

 

 

6:0

Reserved.

 

 

 

62

Intel® 82845 MCH for SDR Datasheet

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Intel 845 manual FDHC-Fixed Dram Hole Control Register Device, Address Offset 97h Default Value 00h Access Size Bits