EMM386 was Microsoft's expanded memory manager, which created expanded memory using extended memory on Intel 80386 CPUs. It appeared with Windows/386 2.1 and later with MS-DOS 5.0. Just as the other expanded memory managers, it leveraged the virtual 8086 mode of the processor. It also had other functions related to Windows, notably most probably was managing the virtualization of DOS windows and was acting as the actual protected mode Windows kernel.
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