Epson Equity III, Информационный бюллетень по поддержке продукции

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Product Support Bulletin
Subject: Using Expanded Memory with Equity and Apex Computers
Date: 3/2/90
Page: 1 of 6
PSB No: S-0047C
Originator: KAS
Q1. What is Expanded Memory?
A. Conventional memory, managed by MS - DOS, is limited to 640K. In
response to the need for greater amounts of accessible memory, the
LIM EMS (Lotus/Intel/Microsoft Expanded Memory Specification) was
introduced in 1984. EMS, version 3.2, provides usable memory
beyond the 640K limit through “bank switching”. The expanded
memory is divided into 16K portions called “pages”. The computer
accesses these pages through a “page frame” or “window” which is
64K of memory located between 768K and 896K in 80286 - based
systems and between 800K and 960K in 8086 - or 8088 - based
systems.
16K pages of memory are allocated for an application’s
use and the EMM (Expanded Memory Manager) handles the job of
mapping the pages in and out of the page frame as they are
needed. However, in order to make use of expanded memory, the
software must be written to take advantage of the EMS. Software
such as Lotus 1 - 2 - 3, Microsoft Windows and Borland’s SideKick
Plus make use of expanded memory. EMS is limited to 8Mb of
expanded memory.
Q2. What is EEMS?
A.
A superset of EMS, AQA EEMS (AST/Quadram/Ashton - Tate
Enhanced Expanded Memory Specification) provides greater flexibility
in the mapping of expanded memory. However, it also uses the
technique of “bank switching” and has its own memory manager
which accommodates such specially written software as Quarterdeck’s
DESQview. EEMS is also limited to 8Mb of expanded memory.