Expanded Memory Specification
<storage> (EMS) An IBM PC memory paging scheme enabling access to memory
other than conventional memory in real mode.
Expanded memory is provided through a page frame of at least 64 kilobytes in the
reserved memory address region. Access to this memory is provided by an expanded
memory manager (EMM) software. The EMM functions are accessible through
In 8086 or 8088 based systems this is the only way to use memory beyond
conventional memory. In systems based on 80286 or later, XMS and HMA provide
EMS was developed jointly by Lotus, Intel, and Microsoft prior to 1988.
Accordingly, this specification is sometimes referred to as LIM EMS.
A complete discussion of EMS and programming examples can be found in ["PC
System Programming for developers", 1989, ISBN 1-55755-035-2 (Book only) and
ISBN 1-55755-036-0 (Book and diskette)].
EEMS, a competing expanded memory management standard, was developed by AST
Research, Quadram and Ashton-Tate.
See also upper memory block.
expanded memory « expanded memory manager « expanded
memory page frame « Expanded Memory Specification
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