Register Description

Table 21.

PAM Registers and Associated System Memory Segments

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

PAM Reg

 

Attribute Bits

 

System Memory Segment

 

Comments

Offset

 

 

 

 

 

 

 

 

 

 

 

 

PAM0[3:0]

 

 

 

 

Reserved

 

 

59h

 

 

 

 

 

 

 

 

 

 

 

 

 

PAM0[7:4]

R

 

R

WE

RE

 

0F0000h–0FFFFFh

 

BIOS Area

59h

 

 

 

 

 

 

 

 

 

 

 

 

 

PAM1[3:0]

R

 

R

WE

RE

 

0C0000h–0C3FFFh

 

ISA Add-on BIOS

5Ah

 

 

 

 

 

 

 

 

 

 

 

 

 

PAM1[7:4]

R

 

R

WE

RE

 

0C4000h–0C7FFFh

 

ISA Add-on BIOS

5Ah

 

 

 

 

 

 

 

 

 

 

 

 

 

PAM2[3:0]

R

 

R

WE

RE

 

0C8000h–0CBFFFh

 

ISA Add-on BIOS

5Bh

 

 

 

 

 

 

 

 

 

 

 

 

 

PAM2[7:4]

R

 

R

WE

RE

 

0CC000h–0CFFFFh

 

ISA Add-on BIOS

5Bh

 

 

 

 

 

 

 

 

 

 

 

 

 

PAM3[3:0]

R

 

R

WE

RE

 

0D0000h–0D3FFFh

 

ISA Add-on BIOS

5Ch

 

 

 

 

 

 

 

 

 

 

 

 

 

PAM3[7:4]

R

 

R

WE

RE

 

0D4000h–0D7FFFh

 

ISA Add-on BIOS

5Ch

 

 

 

 

 

 

 

 

 

 

 

 

 

PAM4[3:0]

R

 

R

WE

RE

 

0D8000h–0DBFFFh

 

ISA Add-on BIOS

5Dh

 

 

 

 

 

 

 

 

 

 

 

 

 

PAM4[7:4]

R

 

R

WE

RE

 

0DC000h–0DFFFFh

 

ISA Add-on BIOS

5Dh

 

 

 

 

 

 

 

 

 

 

 

 

 

PAM5[3:0]

R

 

R

WE

RE

 

0E0000h–0E3FFFh

 

BIOS Extension

5Eh

 

 

 

 

 

 

 

 

 

 

 

 

 

PAM5[7:4]

R

 

R

WE

RE

 

0E4000h–0E7FFFh

 

BIOS Extension

5Eh

 

 

 

 

 

 

 

 

 

 

 

 

 

PAM6[3:0]

R

 

R

WE

RE

 

0E8000h–0EBFFFh

 

BIOS Extension

5Fh

 

 

 

 

 

 

 

 

 

 

 

 

 

PAM6[7:4]

R

 

R

WE

RE

 

0EC000h–0EFFFFh

 

BIOS Extension

5Fh

 

 

 

 

 

 

 

 

 

 

 

 

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 system memory controlled by the GMCH, while the 128-kB address range from 080000 to 09FFFFh can be mapped to PCI0 or to main DDR SDRAM. By default this range is mapped to main system memory and can be declared as a main system memory hole (accesses forwarded to PCI0) via GMCH's 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 PCI2 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 GMCH.

This area can be programmed as SMM area via the SMRAM register. When the GMCH is strapped in other mode, or when used as an SMM space, this range can not be accessed from the Hub interface.

Expansion Area (C0000h-DFFFFh)

This 128-kB area is divided into eight 16-kB segments that can be assigned with different attributes via PAM Control register as defined in Figure 4 and Table 21.

D15343-003

63

Page 63
Image 63
Intel D15343-003 manual PAM Registers and Associated System Memory Segments, DOS Application Area 00000h-9FFFh