In computing, protected mode, also called protected virtual address mode,[1] is an operational mode of x86-compatible central processing units (CPU). It allows system software to utilize features such as virtual memory, paging, safe multi-tasking, and other features designed to increase an operating system's control over application software.[2][3]
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.[4] 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).[5]
Protected mode was first added to the x86 architecture in 1982,[6] with the release of Intel's 80286 (286) processor, and later extended with the release of the 80386 (386) in 1985.[7] 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.[8]
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