In computing, protected mode, also called protected virtual address mode, is an operational mode of x86-compatible central processing units (CPU). It allows system software to use features such as virtual memory, paging and safe multi-tasking designed to increase an operating system's control over application software.
When a processor that supports x86 protected mode is powered on, it begins executing instructions in real mode, in order to maintain backwards compatibility with earlier x86 processors. Protected mode may only be entered after the system software sets up several descriptor tables and enables the Protection Enable (PE) bit in the control register 0 (CR0).
Protected mode was first added to the x86 architecture in 1982, with the release of Intel's 80286 (286) processor, and later extended with the release of the 80386 (386) in 1985. Due to the enhancements added by protected mode, it has become widely adopted and has become the foundation for all subsequent enhancements to the x86 architecture.
Read more about Protected Mode: History, 386 Additions To Protected Mode, Entering and Exiting Protected Mode, Features, Operating Systems
Famous quotes containing the words protected and/or mode:
“If one really wishes to know how justice is administered in a country, one does not question the policemen, the lawyers, the judges, or the protected members of the middle class. One goes to the unprotected—those, precisely, who need the laws’s protection most!—and listens to their testimony.”
—James Baldwin (1924–1987)
“The only mode of obtaining an answer to these questions of the senses is to forego all low curiosity, and, accepting the tide of being which floats us into the secret of nature, work and live, work and live, and all unawares the advancing soul has built and forged for itself a new condition, and the question and the answer are one.”
—Ralph Waldo Emerson (1803–1882)