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Emm386




The technique probably first appeared with the development of CEMM , included with Compaq DOS 3.31 in 1987. Microsoft's version first appeared, built-in, with Windows/386 2.1 in 1988 and as standalone EMM386.SYS with MS-DOS 4.01 in 1989; the more flexible EMM386.EXE version appeared in MS-DOS 5.0 in 1991.

Just as the other expanded memory managers, EMM386 uses the processor's Virtual 8086 Mode . It temporarily shuts down during a Windows session in ''386 Enhanced'' mode, with Windows' Protected Mode kernel taking over its role.

EMM386.EXE can map memory into unused blocks in the Upper Memory Area , allowing device drivers and TSR s to be "loaded high", preserving precious Conventional Memory . (For details, see Upper Memory Area .)


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