301467-005 Datasheet, PDF (209/426 Pages) Intel Corporation – Express Chipset

System Address Map
R
Compatible SMRAM Address Range (A_0000h–B_FFFFh)
When compatible SMM space is enabled, SMM-mode processor accesses to this range are routed
to physical system DRAM at 000A 0000h–000B FFFFh. Non-SMM-mode processor accesses to
this range are considered to be to the Video Buffer Area as described above. PCI Express and
DMI originated cycles to enabled SMM space are not allowed and are considered to be to the
Video Buffer Area if IGD (82915G/82915GV/82915GL/82910GL GMCH only) is not enabled as
the VGA device. PCI Express and DMI initiated cycles are attempted as peer cycles, and will
master abort on PCI if no external VGA device claims them.
Monochrome Adapter (MDA) Range (B_0000h–B_7FFFh)
Legacy support requires the ability to have a second graphics controller (monochrome) in the
system. Accesses in the standard VGA range are forwarded to IGD, PCI Express, or the DMI
(depending on the programming of the on-chip registers). Since the monochrome adapter may be
mapped to any one of these devices, the (G)MCH must decode cycles in the MDA range
(000B_0000h – 000B_7FFFh) and forward either to IGD, PCI Express, or the DMI. In addition to
the memory range B0000h to B7FFFh, the (G)MCH decodes I/O cycles at 3B4h, 3B5h, 3B8h,
3B9h, 3BAh and 3BFh and forwards them to the either IGD, PCI Express, and/or the DMI.
11.1.3 Expansion Area (C_0000h–D_FFFFh)
This 128-KB ISA Expansion region (000C_0000h – 000D_FFFFh) is divided into eight, 16-KB
segments. Each segment can be assigned one of four read/write states: read only, write only,
read/write, or disabled. Typically, these blocks are mapped through the (G)MCH and are
subtractively decoded to ISA space. Memory that is disabled is not remapped.
Non-snooped accesses from PCI Express or DMI to this region are always sent to main memory.
Table 11-1. Expansion Area Memory Segments
Memory Segments
0C0000h–0C3FFFh
0C4000h–0C7FFFh
0C8000h–0CBFFFh
0CC000h –0CFFFFh
0D0000h–0D3FFFh
0D4000h–0D7FFFh
0D8000h–0DBFFFh
0DC000h–0DFFFFh
Attributes
W/R
W/R
W/R
W/R
W/R
W/R
W/R
W/R
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Datasheet
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