EMM
Short for Expanded Memory Manager, EMM is a device driver that allows MS-DOS computers to use expanded memory. Intel 80286 and lower computers required an expansion memory board and software in order to utilize an extended memory manager. However, 386 computers and higher require only a software memory manager. A good example of an EMM is EMM386.EXE, which is a MS-DOS memory manager used with Intel 80386 computers and higher.
Also see: Memory definitions, Memory manager