Virtual mode 8086

The virtual mode 8086 - in English “ Virtual 8086 mode” - is a particular procedure for the processors of the family x86. This mode was created with the apparation of the processor Intel 80386 in 1985 and is available on all the higher versions of this processor.

The virtual mode 8086, also called Virtual 8086 or V86, makes it possible the processor to behave like several processors 8086 or 8088 functioning in a concurrent way. This procedure was created to make function multiple applications DOS (Multitâche) in real Mode at the same time as of the applications Windows 32 bits in Mode protected.

In practice the virtual mode 8086 divides the space of addressing into multiple subspaces, just like a virtual Machine, and maintains a list of the virtual registers. This mode uses the segmentation of the real mode but uses the addresses memory on 21 bits what results in a space from linear addressing prone to the Pagination. The programs DOS (which they are 16 or 32 bits) functioning in protected mode are not carried out through the virtual mode 8086 but as a user mode - provided that they are compatible DPMI (DOS Protected Mode Interfaces).

The virtual mode 8086 is used in particular under Windows 2.0, Windows 3.x, Windows 9x, Windows Me and OS/2 2.x. It was used later under virtual machines DOS, SCO UNIX through Merge under Linux thanks to, for example, DosEmu. Advanced virtual machines as for example VMWARE allow the use of this mode.

See too

real Mode
Mode protected
IA-32
X86

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