jeff@sunvice.UUCP (Jeff Rabin-Sun-Ft. Lauderdale FL-SE) (01/04/90)
Could someone please post short definitions for LIMM, EEMS, EMS and any relationships between them. Which is hardware dependent, and which is software? In addition, what's PHARLAP? I believe it's a memory management scheme for EMS . . . TIA-Jeff Rabin
kaleb@mars.jpl.nasa.gov (Kaleb Keithley) (01/05/90)
In article <7682@sunvice.UUCP> jeff@sunvice.UUCP (Jeff Rabin-Sun-Ft. Lauderdale FL-SE) writes: >Could someone please post short definitions for LIMM, EEMS, EMS and any >relationships between them. Which is hardware dependent, and which is >software? > >In addition, what's PHARLAP? I believe it's a memory management scheme >for EMS . . . > LIM-EMS means Lotus Intel Microsoft Expanded Memory Specification... originally developed to provide an expanded memory scheme that would work on all DOS machines. In general (if not specifically) it involves hardware paging of memory on an LIM EMS board into a hole in ROM above A000:0000. The current revision of this standard is 4.0. Extended memory involves the address range that is available using the 286 (and up) in protected mode. The BIOS on most (if not all) AT class machines has routines to move data to and from memory above 1Meg. I won't speak on EEMS because I don't know what it is. Pharlap is a vendor that supplies DOS extender software that allows programs to run in protected mode on a 386. They also have compilers and assemblers that generate protected mode 386 code to take advantage of their DOS extender. Chewey, get us outta here! kaleb@mars.jpl.nasa.gov (818)354-8771 Kaleb Keithley
cs4g6ag@maccs.dcss.mcmaster.ca (Stephen M. Dunn) (01/07/90)
In article <7682@sunvice.UUCP> jeff@sunvice.UUCP (Jeff Rabin-Sun-Ft. Lauderdale FL-SE) writes:
$Could someone please post short definitions for LIMM, EEMS, EMS and any
$relationships between them. Which is hardware dependent, and which is
$software?
LIM: Lotus-Intel-Microsoft. This refers to the fact that the EMS 3.2 and
higher specs were produced jointly by these three companies.
EMS: Expanded Memory Specification. This is the particular spec (e.g. 3.2
or 4.0) used; also identifies the spec as one of the LIM family.
EEMS: I forget what the first E stands for. This is an enhancement to
EMS 3.2 from (I believe) Ashton-Tate, Quadram, and AST which allows
things like mapping memory into the conventional memory area. Most,
if not all, of this was included into EMS 4.0.
The design of the hardware is left up to the manufacturer; the hardware
is interfaced to the user's software through the EMM (Expanded Memory Manager)
which is a driver that you include in your config.sys file. All EMMs for a
given spec (e.g. EMS 4.0) provide the same interface to the software. Due
to hardware differences, the EMM for a given piece of hardware generally will
work only on that particular board.
I quote from _Advanced MS-DOS_, first edition (Duncan), p. 441, without
permission:
The Lotus/Intel/Microsoft Expanded Memory Specification (EMS)
defines a hardware/software subsystem, compatible with 8088/
8086/80286-based microcomputers running MS-DOS, that allows
applications to access as much as 8 megabytes of bank-switched
random access memory.
And now from page 182:
At the Spring COMDEX in 1985, Lotus Development Corporation and
Intel Corporation jointly announced the Expanded Memory Specification
3.0 (EMS), which was designed to head off rapid obsolescence of the
older PCs due to limited memory. Shortly afterward, Microsoft
announced that it would support the EMS ... Subsequently, the
Expanded Memory Specification 3.2, modified from 3.0 ... was
released as a joint effort of Lotus, Intel and Microsoft.
The Intel/Lotus/Microsoft Expanded Memory Speficiation is a func-
tional definition of a bank-switched memory-expansion subsystem.
It is comprised of hardware expansion modules and a resident driver
program specific to those modules.
The EMS provides a uniform means for applications to access as much
as 8 megabytes of memory. The supporting software ... provides a
hardware-independent interface between application software and the
expanded memory board(s).
(The first edition is too old to cover EEMS or EMS 4.0)
--
Stephen M. Dunn cs4g6ag@maccs.dcss.mcmaster.ca
<std_disclaimer.h> = "\nI'm only an undergraduate!!!\n";
****************************************************************************
If it's true that love is only a game//Well, then I can play pretendcs4g6ag@maccs.dcss.mcmaster.ca (Stephen M. Dunn) (01/07/90)
In article <2504@jato.Jpl.Nasa.Gov> kaleb@mars.UUCP (Kaleb Keithley) writes:
$ [...] In general (if not specifically) it involves hardware paging of
$memory on an LIM EMS board into a hole in ROM above A000:0000. The current
$revision of this standard is 4.0. [...]
Pretty close. EMS 3.2 and earlier mapped four 16K pages into one
64K segment in an address hole above segment A000. EMS 4.0 allows you to
have substantially more than four pages, including the possibility to map
expanded memory into large portions of the conventional memory space (the
first 640K of memory) to allow quick switching of that memory space for
multitasking operating systems (previously, the contents of memory would
have been copied into EMS 64K at a time, and the new contents would have
been copied down from EMS right after this ... time-consuming, to say the
least).
--
Stephen M. Dunn cs4g6ag@maccs.dcss.mcmaster.ca
<std_disclaimer.h> = "\nI'm only an undergraduate!!!\n";
****************************************************************************
If it's true that love is only a game//Well, then I can play pretenddarcy@druid.uucp (D'Arcy J.M. Cain) (01/08/90)
In article <25A65F5E.1015@maccs.dcss.mcmaster.ca> cs4g6ag@maccs.dcss.mcmaster.ca (Stephen M. Dunn) writes: > >EEMS: I forget what the first E stands for. This is an enhancement to ^^^^^^^^^^^ Enhanced EMS -- D'Arcy J.M. Cain (darcy@druid) | Thank goodness we don't get all D'Arcy Cain Consulting | the government we pay for. West Hill, Ontario, Canada | No disclaimers. I agree with me |