AC82G41SLGQ3 Datasheet, PDF (57/604 Pages) Intel Corporation – Intel® 4 Series Chipset Family

System Address Map
3.1
Figure 5.
Legacy Address Range
This area is divided into the following address regions:
• 0 – 640 KB – DOS Area
• 640 – 768 KB – Legacy Video Buffer Area
• 768 – 896 KB in 16 KB sections (total of 8 sections) – Expansion Area
• 896 – 960 KB in 16 KB sections (total of 4 sections) – Extended System BIOS Area
• 960 KB - 1 MB Memory – System BIOS Area
DOS Legacy Address Range
000F_FFFFh
000F_0000h
000E_FFFFh
000E_0000h
000D_FFFFh
000C_0000h
000B_FFFFh
000A_0000h
0009_FFFFh
System BIOS (Upper)
64 KB
Extended System BIOS (Lower)
64 KB (16KBx4)
Expansion Area
128 KB (16KBx8)
Legacy Video Area
(SMM Memory)
128 KB
1 MB
960 KB
896 KB
768 KB
640 KB
DOS Area
3.1.1
3.1.2
0000_0000h
DOS Range (0h – 9_FFFFh)
The DOS area is 640 KB (0000_0000h – 0009_FFFFh) in size and is always mapped to
the main memory controlled by the (G)MCH.
Legacy Video Area (A_0000h–B_FFFFh)
The legacy 128 KB VGA memory range, frame buffer, (000A_0000h – 000B_FFFFh) can
be mapped to IGD (Device 2), to PCI Express (Device 1), and/or to the DMI Interface.
The appropriate mapping depends on which devices are enabled and the programming
of the VGA steering bits. Based on the VGA steering bits, priority for VGA mapping is
constant. The (G)MCH always decodes internally mapped devices first. Internal to the
(G)MCH, decode precedence is always given to IGD. The (G)MCH always positively
decodes internally mapped devices, namely the IGD and PCI Express. Subsequent
Datasheet
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