Register and Memory Mapping
5.3
System Memory Map
The Intel® SCH supports up to 2 GB of physical DDR2 memory space and 64 KB+3 of
addressable I/O space. There is a programmable memory address space under the
1 MB region which is divided into regions that can be individually controlled with
programmable attributes such as Disable, Read/Write, Write Only, or Read Only. This
section describes how the memory space is partitioned and how those partitions are
used.
Top of Memory (TOM) is the highest address of physical memory actually installed in
the system. TOM greater than 2GB is not supported.
Memory addresses above 2 GB will be routed to internal controllers or external I/O
devices. Any memory access between TOM and 2 GB will return indeterminate results,
and writes will be ignored.
Figure 3 represents system memory address map in a simplified form.
Figure 3.
System Address Ranges
4 GB
PCI Memory
Address Range
2 GB
(TOM)
Main Memory
Address Range
1 MB
Legacy
Address Range
0
Table 10.
Intel® SCH Memory Map (Sheet 1 of 2)
Starting
Address
Ending
Address
Device
Comment
Legacy Address Range (0 to 1 MB)
Access to this range will be forward to
PCI Express if the Intel Graphics Media
Adapter is disabled.
Legacy Video (VGA)
Expansion Area
000A0000h
000BFFFFh
000C0000h
000E0000h
000DFFFFh
000EFFFFh
Extended BIOS
(LPC)
BIOS (LPC)
LPC
000F0000h
000E0000h
000FFFFFh
000FFFFFh
Main Memory1 (1 MB to Top Of Memory2)
TSEG
Variable
Variable
Variable
Variable
System Management Mode memory
Graphics
60
Datasheet
INTEL [ INTEL ]
