Editing Real mode (section)

{{Short description|Operating mode of all x86-compatible CPUs}}
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{{More citations needed|date=November 2012}}
{{X86 Processor Modes}}

'''Real mode''', also called '''real address mode''', is an operating mode of all [[x86]]-compatible [[Central processing unit|CPUs]]. The mode gets its name from the fact that addresses in real mode always correspond to real locations in memory. Real mode is characterized by a 20-[[bit]] segmented [[memory address]] space (giving 1 [[Megabyte|MB]] of addressable memory) and unlimited direct software access to all addressable memory, I/O addresses and peripheral hardware.  Real mode provides no support for memory protection, multitasking, or code privilege levels.

Before the introduction of [[protected mode]] with the release of the [[Intel 80286|80286]], real mode was the only available mode for x86 CPUs;<ref>{{cite web|url=http://alasir.com/x86ref/|title=x86 CPU Reference (Archived at 8 September 2018 - Instead of 'A Brief x86 History' : alasir.com/x86ref : 403 Forbidden on 24 March 2023)|access-date=March 24, 2023|archive-date=September 8, 2018|archive-url=https://web.archive.org/web/20180908013931/http://alasir.com/x86ref/|url-status=bot: unknown}}</ref> and for [[backward compatibility]], all x86 CPUs start in real mode when reset, though it is possible to emulate real mode on other systems when starting in other modes.