82845MP Datasheet, PDF (107/157 Pages) Intel Corporation – Intel 845 Family Chipset-Mobile 82845MP/82845MZ Chipset Memory Controller Hub Mobile (MCH-M)

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Intel^® 82845MP/82845MZ Chipset-Mobile (MCH-M)
4.1.2.
PAM Memory Spaces
PAMC0
PAMC4
PAMC8
PAMCC
PAMD0
PAMD4
PAMD8
PAMDC
PAME0
PAME4
PAME8
PAMEC
PAMF0
From
0_000C_0000
0_000C_4000
0_000C_8000
0_000C_C000
0_000D_0000
0_000D_4000
0_000D_8000
0_000D_C000
0_000E_0000
0_000E_4000
0_000E_8000
0_000E_C000
0_000F_0000
To
0_000C_3FFF
0_000C_7FFF
0_000C_BFFF
0_000C_FFFF
0_000D_3FFF
0_000D_7FFF
0_000D_BFFF
0_000D_FFFF
0_000E_3FFF
0_000E_7FFF
0_000E_BFFF
0_000E_FFFF
0_000F_FFFF
The 256-KB PAM region is divided into three parts:
• ISA expansion region, a 128-KB area between 0_000C_0000h – 0_000D_FFFFh
• Extended BIOS region, a 64-KB area between 0_000E_0000h – 0_000E_FFFFh
• System BIOS region, a 64-KB area between 0_000F_0000h – 0_000F_FFFFh.
The ISA expansion region 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 MCH-M and are subtractively decoded to ISA space.
The extended System BIOS region is divided into four 16 Kbytes segments. Each segment can be
assigned independent read and write attributes so it can be mapped either to main DRAM or to hub
interface. Typically, this area is used for RAM or ROM.
The system BIOS region is a single 64-Kbytes 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 MCH-M can “shadow” BIOS into main DRAM.
250687-002
Datasheet
107