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PCturbo
286e
Lotus/luteljMicrosoft Expanded Memory
Specification (EMS)
.
The Lotus/Intel/Microsoft Expanded Memory
Specification, or simply EMS Memory, allows
large amounts of memory to be used by programs
running under DOS.
A technique called "paging" allows programs to
address EMS Memory through a 64K block of
memory called the "page frame." The page
frame is located at a range of addresses where
it can be accessed from DOS but does not
interfere with applications software.
It
is
divided into four 16K pages, each of which can
be used as a window to view any 16K page of
EMS Memory.
Notice that paged memory does not have a fixed
\---..-1 - ___
~
address; the hardware makes it apoear at an
'----'
address accessible from DOS. This makes EMS
different from Protected Memory, which is not
paged and occupies the addresses above 1 ME.
5-8
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