PSE-36

rdf:langString PSE-36

rdf:langString In computing, PSE-36 (36-bit Page Size Extension) refers to a feature of x86 processors that extends the physical memory addressing capabilities from 32 bits to 36 bits, allowing addressing to up to 64 GB of memory. Compared to the Physical Address Extension (PAE) method, PSE-36 is a simpler alternative to addressing more than 4 GB of memory. It uses the Page Size Extension (PSE) mode and a modified page directory table to map 4 MB pages into a 64 GB physical address space. PSE-36's downside is that, unlike PAE, it doesn't have 4-KB page granularity above the 4 GB mark. PSE-36 was introduced into the x86 architecture with the Pentium II Xeon and was initially advertised as part of the "Intel Extended Server Memory Architecture" (sometimes abbreviated ESMA), a branding which also included the slightly older PAE (and thus the Pentium Pro, which only supported PAE, was advertised as having only "subset support" for ESMA). The heyday of PSE-36 was relatively brief. PSE-36's main advantage was that, unlike PAE, it required little rework of the operating system's internals, and thus PSE-36 proved a suitable stopgap measure around the Windows NT 4.0 Enterprise Edition timeframe. Newer Microsoft operating systems, including Windows 2000, support only PAE. Some operating systems like Linux skipped PSE-36 entirely. Despite this, AMD and later Intel chose to provide up to 40 bits PSE support in their 64-bit processors, when operated in legacy mode.