Path: utzoo!attcan!uunet!lll-winken!lll-lcc!ames!ncar!gatech!udel!rochester!pt.cs.cmu.edu!b.gp.cs.cmu.edu!Ralf.Brown@B.GP.CS.CMU.EDU
From: Ralf.Brown@B.GP.CS.CMU.EDU
Newsgroups: comp.sys.ibm.pc
Subject: Re: Use of expanded memory on System 2 Model 50
Message-ID: <22df3aad@ralf>
Date: 16 Jul 88 11:14:53 GMT
Sender: netnews@pt.cs.cmu.edu
Lines: 25
In-Reply-To: <1410@lznv.ATT.COM>

In article <1410@lznv.ATT.COM>, psc@lznv.ATT.COM (Paul S. R. Chisholm) writes:
}(that's me) writes at great length about how unlikely it is that you're
}going to be able to use that 360K as conventional memory.  Well, as
}part of their Windows/286 (a.k.a. Windows 2.1) product, Microsoft is
}distributing a device driver that lets you get an extra 64K of
}conventional memory out of your extended (AT style, not LIM EMS)
}memory.  This memory can be used by non-Windows applications.  PC Week,
}
}If all you needed was 704K total, and you're not using extended memory
}for anything else, you're all set.

Except that the extra 64K will not be contiguous with the base 640K, thus
making it unusable unless the program is specifically written to take 
advantage of it.  BTW, DESQview has had an equivalent driver for over a year.
The driver works because of a quirk of the 80286 that lets it access almost 
64K more than 1meg in real mode (up to FFFF:FFFF, which would have wrapped
back to 0000:FFEF on an 808[68] machine).

On a PS/2 mod 50 or 60, there is circuitry present to run the extra memory as
either exTENDed or LIM EMS (Quarterdeck's QEMM-50/60 makes it EMS) memory.

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