301467-005 Datasheet, PDF (208/426 Pages) Intel Corporation – Express Chipset

System Address Map
R
Figure 11-2. Microsoft MS-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)
64KB
Extended System BIOS (Lower)
64KB (16KBx4)
Expansion Area
128KB (16KBx8)
Legacy Video Area
(SMM Memory)
128KB
1MB
960KB
896KB
768KB
640KB
DOS Area
0000_0000h
11.1.1
11.1.2
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, to PCI Express, and/or to the DMI. The appropriate mapping is programmable.
Based on the programming, priority for VGA mapping is constant. The (G)MCH always decodes
internally mapped devices first. Internal to the 82915G/82915GV/82915GL/82910GL GMCH,
decode precedence is always given to the IGD. The (G)MCH always positively decodes internally
mapped devices, namely the IGD (82915G/82915GV/82915GL/82910GL only) and PCI Express.
Subsequent decoding of regions mapped to PCI Express or the DMI depends on the
programming. This region is also the default for SMM space.
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Datasheet