Physical Address Extension
A workaround first developed in the Pentium Pro, known as Physical Address Extension, allows certain 32-bit operating systems to access up to 36-bit memory addresses, even though individual programs are still limited to operating within 32 bits of address space. Each program can have its own 4 gigabyte addressing space, together utilizing up to 64 gigabytes of memory across all programs. This was fully supported in Windows XP up to the Service Pack 1 (SP1) release, but then withdrawn for SP2; the only 32-bit versions of Microsoft Windows to fully support this are certain high-end server versions of Windows Server 2003 and earlier; it remained in use by some 32-bit Linux distributions. Microsoft disabled the support in Windows XP SP2 and later operating systems because there were many compatibility problems with graphics card and other devices, which needed PAE-aware drivers, distinct from both standard 32-bit and later 64-bit drivers. Many versions of MS Windows can activate what is still called Physical Address Extensions for the purpose of using the NX bit, but this no longer extends the address space.
Read more about this topic: PCI Hole
Famous quotes containing the words physical, address and/or extension:
“[In early adolescence] she becomes acutely aware of herself as a being perceived by others, judged by others, though she herself is the harshest judge, quick to list her physical flaws, quick to undervalue and under-rate herself not only in terms of physical appearance but across a wide range of talents, capacities and even social status, whereas boys of the same age will cite their abilities, their talents and their social status pretty accurately.”
—Terri Apter (20th century)
“It is not from the benevolence of the butcher, the brewer, or the baker, that we expect our dinner, but from their regard to their own interest. We address ourselves, not to their humanity but to their self-love, and never talk to them of our necessities but of their advantages.”
—Adam Smith (1723–1790)
“We are now a nation of people in daily contact with strangers. Thanks to mass transportation, school administrators and teachers often live many miles from the neighborhood schoolhouse. They are no longer in daily informal contact with parents, ministers, and other institution leaders . . . [and are] no longer a natural extension of parental authority.”
—James P. Comer (20th century)