Computer Learning

[j.c.]

Physical Address Extension...
anyone know if there is any advantage/disadvantage of having it enabled if you don't have 4G of memory installed?

Processor:
1.87 gigahertz Intel Pentium M
64 kilobyte primary memory cache
2048 kilobyte secondary memory cache

2040 Megabytes Installed Memory

Win XP Pro SP3

If I leave it enabled does it use more processing to access the memory? If I disable it will it reduce the amount of memory it can access? Will it disable DEP and do I need that? TIA

Physical Address Extension

Physical Address Extension (PAE) enables x86 processors to access up to 64 GB of physical memory and x64 processors to access up to 1024 GB of physical memory. PAE is supported by 32-bit Windows Server systems to enable access to up to 128 GB of physical memory. However, note that each process on 32-bit Windows is still limited to a 4 GB virtual address space. For details, see Memory Limits for Windows Releases.

PAE also enables several advanced system and processor features, including hardware-enabled Data Execution Prevention (DEP), non-uniform memory access (NUMA), and the ability to add memory to a system while it is running (hot-add memory).

With PAE, the operating system moves from two-level linear address translation to three-level address translation. The extra layer of translation provides access to physical memory beyond 4 GB. Instead of a linear address being split into three separate fields for indexing into memory tables, it is split into four separate fields: a 2-bit field, two 9-bit fields, and a 12-bit field that corresponds to the page size implemented by Intel Architecture (4 KB).
http://msdn.microsoft.com/en-us/library/aa366796(VS.85).aspx