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== Physical Address Extension ==

All Intel processors since Pentium Pro (with exception of the Pentium M at 400 Mhz) and all AMD since the Athlon series implement the [[PAE|Physical Address Extension]] (PAE). This feature allows you to access up to 64 GiB (2^36) of RAM. You can check for this feature using CPUID. Once checked, you can activate this feature by setting bit 5 in CR4. Once active, the CR3 register points to a table of 4 64-bit entries, each one pointing to a page directory made of 4096 bytes (like in normal paging), divided into 512 64-bit entries, each pointing to a 4096 byte page table, divided into 512 64bit page entries.

 

== Usage ==