System Address Map

R

Figure 4. DOS Compatible Area Address Map

 

0C0000h

Standard PCI/ISA

0B8000h

 

Video Memory

0B0000h

(SMM Memory)

 

 

0A0000h

Upper, Lower,

Expansion Card BIOS

and Buffer Area

Monochrome Display

Adapter Space

1 MB

 

Controlled by

 

PAM[6:0]

768 KB

 

736 KB

Controlled by

 

VGA Enable and

704 KB

MDA Enable

 

640 KB

 

= Optional AGP

= Optional System Memory

= System Memory

sys_addr_map_2

Figure 5. Extended Memory Range Address Map

 

 

 

1_0000_0000 (4 GB)

 

High BIOS, Optional

 

 

 

 

 

 

 

extended SMRAM

 

 

 

 

 

 

 

FF00_0000

 

Hub Interface

 

 

 

 

 

 

 

(always)

 

FEF0_0000

 

 

 

 

Local APIC Space

 

 

 

 

 

 

 

 

 

FEE0_0000

 

Hub Interface

 

 

 

 

 

 

 

(always)

 

 

 

 

 

 

 

FED0_0000

 

I/O APIC Space

 

 

 

 

 

 

 

 

 

FEC8_0000

 

I/O APIC Space

 

 

 

 

 

 

 

 

 

FEC0_0000

 

AGP/PCI

 

 

 

 

 

 

 

 

 

Top of Low Memory (TOM)

 

Extended SMRAM

 

 

 

 

 

 

 

Space

 

TEM - TSEG

 

 

 

 

 

 

100C_0000

 

Extended SMRAM

 

 

 

 

 

 

 

(translated to < 1 MB)

 

 

 

 

 

 

 

100A_0000

 

 

 

 

 

 

0100_0000 (16 MB)

 

ISA Hole

 

 

 

 

 

= System Memory Region

 

 

 

 

 

 

 

00F0_0000 (15 MB)

 

 

 

 

 

 

 

= Optional System Memory Region

 

 

 

 

 

 

 

 

0010_0000 (1 MB)

 

 

 

 

 

 

 

 

 

 

sys_addr_map_3

 

 

 

 

 

 

98

Intel® 82845 MCH for SDR Datasheet

Page 98
Image 98
Intel 845 manual DOS Compatible Area Address Map