PAE (sometimes called PAE-X86) was first implemented by Intel in 1995 in certain models of the Pentium Pro. The PAE IA-32 architecture supports 4 additional address lines for memory selection, so physical address size increases from 32 bits to 36 bits. This enables 4Gb x 2*4 = 64Gb of physical memory to be accessed. The CPUID flag for PAE support is, naturally, PAE. Since then virtually every 32-bit CPU produced comes with PAE support. Even with a PAE-enabled CPU, the IPL32 programming model (IA32 flat memory mode) continues to be able to only see 4 Gb of memory. You need
