Editing Protected mode (section)

=== The 386 ===
[[File:Ic-photo-intel-A80386DX-33-IV-(386DX).png|thumb|An Intel 80386 microprocessor]]
{{details|Intel 80386}}

With the release of the 386 in 1985,<ref name="i386 release date" /> many of the issues preventing widespread adoption of the previous protected mode were addressed.<ref name="Memory usage" /> The 386 was released with an address bus size of 32 bits, which allows for 2<sup>32</sup> bytes of memory accessing, equivalent to 4 [[gigabytes]].<ref name="Memory increases">{{cite book | title = 80386 Programmer's Reference Manual | url = http://bitsavers.org/components/intel/80386/230985-001_80386_Programmers_Reference_Manual_1986.pdf | date = 1986 | publisher = Intel | location = Santa Clara, CA | at = Section 2.1 Memory Organization and Segmentation }}</ref> The segment sizes were also increased to 32 bits, meaning that the full address space of 4 gigabytes could be accessed without the need to switch between multiple segments.<ref name="Memory increases" /> In addition to the increased size of the address bus and segment registers, many other new features were added with the intention of increasing operational security and stability.<ref name="Enhancements">{{ cite book | title = Intel 64 and IA-32 Architectures Software Developer's Manual Volume 1: Basic Architecture | publisher = [[Intel]] | at = Section 3.1 Modes of Operation |date=May 2019 | url = https://software.intel.com/en-us/download/intel-64-and-ia-32-architectures-software-developers-manual-volume-1-basic-architecture }}</ref> Protected mode is now used in virtually all modern [[operating system]]s which run on the x86 architecture, such as [[Microsoft Windows]], [[Linux]], and many others.<ref name="Protected mode use">{{ cite book | title = Write Great Code | publisher = O'Reilly | first = Randall | last = Hyde | chapter = 12.10. Protected Mode Operation and Device Drivers |date=November 2004 | isbn = 1-59327-003-8 | chapter-url = http://safari.oreilly.com/1593270038/ns1593270038-CHP-12-SECT-10 }}</ref>

Furthermore, learning from the failures of the 286 protected mode to satisfy the needs for [[multiuser DOS]], Intel added a separate [[virtual 8086 mode]],<ref>[[Charles Petzold]], Intel's 32-bit Wonder: The 80386 Microprocessor, ''[[PC Magazine]]'', November 25, 1986, pp. 150-152</ref> which allowed multiple virtualized 8086 processors to be emulated on the 386. [[x86 virtualization|Hardware x86 virtualization]] required for virtualizing the protected mode itself, however, had to wait for another 20 years.<ref>{{cite web|url=http://www.infoworld.com/article/2664741/computer-hardware/sending-software-to-do-hardware-s-job.html|title=Sending software to do hardware's job|author=Tom Yager|date=6 November 2004|work=InfoWorld|access-date=24 November 2014}}</ref>