JG82852GMSL7VP Datasheet, PDF (115/176 Pages) Intel Corporation – Intel® 852GM/852GMV Chipset Intel® 852GM/852GMV Chipset Hub (GMCH)

Intel 852GM/852GMV GMCH System Address Map
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4.3.
Monochrome Adapter (MDA) Range (B0000h - B7FFFh)
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 and the Hub Interface (depending on
configuration bits). Since the monochrome adapter may be mapped to anyone of these devices, the
GMCH must decode cycles in the MDA range and forward them either to IGD or to Hub Interface. This
capability is controlled by a VGA steering bits and the legacy configuration bit (MDAP bit). In addition
to the System Memory range B0000h to B7FFFh, the GMCH decodes IO cycles at 3B4h, 3B5h, 3B8h,
3B9h, 3BAh, and 3BFh and forwards them to the either the IGD or the Hub Interface.
Expansion Area (C0000h-DFFFFh)
This 128-kByte ISA Expansion region is divided into eight 16-kByte 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 GMCH and are subtractively decoded to ISA space. System Memory that is
disabled is not remapped.
Extended System BIOS Area (E0000h-EFFFFh)
This 64-kByte area is divided into four 16-kByte segments. Each segment can be assigned independent
read and write attributes so it can be mapped either to main DDR SDRAM or to Hub Interface.
Typically, this area is used for RAM or ROM. System Memory segments that are disabled are not
remapped elsewhere.
System BIOS Area (F0000h-FFFFFh)
This area is a single 64-kByte segment. This segment can be assigned read and write attributes. It is by
default (after reset) Read/Write disabled and cycles are forwarded to Hub Interface. By manipulating the
Read/Write attributes, the GMCH can “shadow” BIOS into the main DDR SDRAM. When disabled,
this segment is not remapped.
Extended System Memory Area
This System Memory area covers 100000h (1 MB) to FFFFFFFFh (4 GB-1) address range and it is
divided into the following regions:
Main System Memory from 1 MByte to the Top of System Memory; maximum 512 MB.
PCI Memory space from the Top of System Memory to 4 GB with two specific ranges.
APIC Configuration Space from FEC0_0000h (4 GB-20 MB) to FECF_FFFFh and FEE0_0000h
to FEEF_FFFFh
High BIOS area from 4 GByte to 4 GByte - 2 MB
Intel^® 852GM/852GMV Chipset GMCH Datasheet
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