Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!tut.cis.ohio-state.edu!zaphod.mps.ohio-state.edu!sdd.hp.com!decwrl!uunet!drivax!liberato
From: liberato@drivax.UUCP (Jimmy Liberato)
Newsgroups: comp.sys.ibm.pc.misc
Subject: Re: Extended and Expanded memory
Message-ID: <8X8NVY2@drivax.UUCP>
Date: 20 Aug 90 02:34:10 GMT
References: <26045@bellcore.bellcore.com> <1990Aug18.110404.28864@cbnewsl.att.com>
Reply-To: liberato%drivax@uunet.uu.net (Jimmy Liberato)
Distribution: usa
Organization: Digital Research, Inc., Monterey, California
Lines: 34

rl@cbnewsl.att.com (roger.h.levy) writes:

>In article <26045@bellcore.bellcore.com>, wind@rruxi.bae.bellcore.com (Wind Chen) writes:
>> LIM 3.2 and LIM 4.0 are two different things, they are not compatible.
>> To use LIM 4.0, you will need hardware support...
>>...

>Yes they are different but most of the rest is untrue.  From the Waite Group's
>MSDOS Developer's Guide:

>	The user does not have to buy any new hardware to use applications
>	that are written to the LIM EMS 4.0 specification.  Older expanded
>	memory boards designed for the LIM EMS 3.2 specification can
>	support the 4.0 specification - the manufacturer just has to write
>	a new EMM to implement the 4.0 function calls.

>Established manufacturers such as AST do just this sort of thing.  Also, the
>LIM 3.2 function calls exist in LIM 4.0 but 4.0 has more of them.  I would
>call that "upward compatible" rather than "not compatible."

Both of these comments are correct in a way.  Though I can add a manufacturers
new 4.0 driver to a 3.2 board and gain some features, there does seem to be
a subclass of 4.0 that lacks the hardware dependent features of "genuine" 4.0
such as backfilling and mutitasking capabilities.  There are tons of Everex
boards out there that fall into this nether region.  Rule of thumb: if it is
inexpensive it is a 3.2 board with a 4.0 driver.  Almost all newer model EMS
boards are now 4.0 at the hardware level.  AST had it easy because their EEMS
standard used on the Rampage included the hardware dependent features
appropriated by the 4.0 standard.  Hence, a four year old Rampage board with a
4.0 driver is the equivalent of a contemporary 4.0 board.

--
Jimmy Liberato   liberat@dri.com
                 ...uunet!drivax!liberato