Intel
82845MP/82845MZ Chipset-Mobile (MCH-M)
250687-002
Datasheet
67
R
Table 23. PAM Register Details
PAM Reg
Attribute Bits
Offset
PAM0[3:0]
Reserved
Memory Segment
Comments
90h
PAM0[7:4]
R
WE
90h
0F0000h - 0FFFFFh
BIOS Area
90h
PAM1[3:0]
R
WE
91h
0C0000h - 0C3FFFh
ISA Add-on BIOS
91h
PAM1[7:4]
R
WE
91h
0C4000h - 0C7FFFh
ISA Add-on BIOS
91h
PAM2[3:0]
R
WE
92h
0C8000h - 0CBFFFh
ISA Add-on BIOS
92h
PAM2[7:4]
R
WE
92h
0CC000h- 0CFFFFh
ISA Add-on BIOS
92h
PAM3[3:0]
R
WE
93h
0D0000h- 0D3FFFh
ISA Add-on BIOS
93h
PAM3[7:4]
R
WE
93h
0D4000h- 0D7FFFh
ISA Add-on BIOS
93h
PAM4[3:0]
R
94h
0D8000h- 0DBFFFh
ISA Add-on BIOS
94h
PAM4[7:4]
R
WE
94h
0DC000h- 0DFFFFh
ISA Add-on BIOS
94h
PAM5[3:0]
R
WE
95h
0E0000h- 0E3FFFh
BIOS Extension
95h
PAM5[7:4]
R
WE
95h
0E4000h- 0E7FFFh
BIOS Extension
95h
PAM6[3:0]
R
WE
96h
0E8000h- 0EBFFFh
BIOS Extension
96h
PAM6[7:4]
R
WE
96h
0EC000h- 0EFFFFh
BIOS Extension
96h
For details on overall system address mapping scheme see the Address Decoding Section of this
document.
DOS Application Area (00000h-9FFFh)
The DOS area is 640 KB in size and it is further divided into two parts. The 512-KB area at 0 to 7FFFFh
is always mapped to the main memory controlled by the MCH-M, while the 128-KB address range from
080000 to 09FFFFh can be mapped to PCI0 or to main DRAM. By default this range is mapped to main
memory and can be declared as a main memory hole (accesses forwarded to PCI0) via MCH-M FDHC
configuration register.
Video Buffer Area (A0000h-BFFFFh)
Attribute bits do not control this 128-KB area. The host -initiated cycles in this region are always
forwarded to either PCI0 or AGP unless this range is accessed in SMM mode. Routing of accesses is
controlled by the Legacy VGA control mechanism of the “virtual” PCI-PCI bridge device
embedded within the MCH-M.
This area can be programmed as SMM area via a special configuration register. When used as SMM
space this range cannot be accessed from the hub interface or AGP.
Expansion Area (C0000h-DFFFFh)
This 128-KB area is divided into eight 16-KB segments, which can be assigned with different attributes
via PAM control register as defined by above.