Protected mode

In computing, protected mode, also called protected virtual address mode, is an operational mode of <a href="/facts/X86/Kypq5fgu">x86</a>-compatible <a href="/facts/Central_processing_unit/Jxp1bqMV">central processing units</a> (CPUs). It allows <a href="/facts/System_software/0faaXG4d">system software</a> to use features such as <a href="/facts/Memory_segmentation/QCUGw5v5">segmentation</a>, <a href="/facts/Virtual_memory/Lw2GemF5">virtual memory</a>, <a href="/facts/Paging/KR889x5k">paging</a> and safe <a href="/facts/Computer_multitasking/Q4acPNMv">multi-tasking</a> designed to increase an operating system's control over <a href="/facts/Application_software/YQuj7Kog">application software</a>.
When a processor that supports x86 protected mode is powered on, it begins executing instructions in <a href="/facts/Real_mode/wfU8vfjn">real mode</a>, in order to maintain <a href="/facts/Backward_compatibility/FbHFBu5y">backward compatibility</a> with earlier x86 processors. Protected mode may only be entered after the system software sets up one descriptor table and enables the Protection Enable (PE) <a href="/facts/Bit/S972NSaD">bit</a> in the <a href="/facts/Control_register/9VGRHh3f">control register</a> 0 (CR0).
Protected mode was first added to the <a href="/facts/X86/Kypq5fgu">x86</a> architecture in 1982, with the release of <a href="/facts/Intel/SMF0gJJX">Intel</a>'s <a href="/facts/80286/rucEU93g">80286</a> (286) processor, and later extended with the release of the <a href="/facts/80386/ag5eSgWv">80386</a> (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 (IA-32) architecture, although many of those enhancements, such as added instructions and new registers, also brought benefits to the real mode.

Protected mode open-in-new

Protected mode