Chapter 2: Installation

2-13

•Due to memory allocation to system devic es, the amount of memory that
remains available for operational use will b e reduced when 4 GB of RAM
is used. The reduction in memory availa bility is disproportional. See the
following table for details.
•For Microsoft Windows users: Microsoft implemented a design change in the
Windows XP with Service Pack 2 (SP2) and Windows Vista. This change is
specic to the behavior of Physical Address Extension (PAE) mode which
improves driver compatibility. For more information, please read the following
article at Microsoft’s Knowledge Base website at: http://support.microsoft.
com/kb/888137.
Possible System Memory Allocation & Availability
System Device Size Physical Memory
Remaining (-Available)
(4 GB Total System
Memory)
Firmware Hub ash memory (System BIOS) 1 MB 3.99
Local APIC 4 KB 3.99
Area Reserved for the chipset 2 MB 3.99
I/O APIC (4 Kbytes) 4 KB 3.99
PCI Enumeration Area 1 256 MB 3.76
PCI Express (256 MB) 256 MB 3.51
PCI Enumeration Area 2 (if needed) -Aligned on 256-MB
boundary-
512 MB 3.01
VGA Memory 16 MB 2.85
TSEG 1 MB 2.84
Memory available to OS and other applications 2.84