This flag was ignored without PSE, but now, the page-directory entry with PS set to 1 does not point to a page table, but to a single large 4 MiB page. The page-directory entry with PS set to 0 behaves as without PSE. If newer PSE-36 capability is available on the CPU, as checked using the CPUID instruction, then 4 more bits, in addition to normal 10 bits, are used inside a page-directory entry pointing to a large page. This allows a large page to be located in 36-bit address space. If Physical Address Extension (PAE) is used, the size of large pages is reduced from 4 MiB down to 2 MiB, and PSE is always enabled, regardless of the PSE bit in codice_2.