Extended Memory
XMS Memory
Extended Memory Specification
A type of memory available on 286-based and
better computers which have memory above
the 1 MB mark.  The HIMEM.SYS device driver
oversees the use of extended memory.

XMS increases available memory for programs
that have been written to take advantage of
it (such as Windows applications and the
SMARTDrive disk cache).
  TECH Help! covers programming aspects of
using XMS in detail.  See XMS and DPMI in
the Index.