Source : Free On-Line Dictionary of Computing

expanded memory
     
         Memory used through {EMS}.  In systems based on
        {Intel 80386} or later processor expanded memory is part of
        the {extended memory} that is mapped into the {expanded memory
        page frame} by the processor.  The mapping is controlled by
        the {EMM}.  In earlier systems, a dedicated {EMS} hardware
        adaptor is needed to map memory into the page frame.  In both
        cases, an appropriate {device driver} is needed for the proper
        communication between hardware and {EMM}.
     
        (1996-01-10)