Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!mcsun!cernvax!chx400!chx400!bernina!neptune!inf.ethz.ch!brandis
From: brandis@inf.ethz.ch (Marc Brandis)
Newsgroups: comp.os.msdos.programmer
Subject: Re: XMS vs EMS (performance)
Message-ID: <25530@neptune.inf.ethz.ch>
Date: 18 Feb 91 10:10:41 GMT
References: <1991Jan30.134859.22160@linus.mitre.org> <1991Feb15.204811.6327@qiclab.scn.rain.com>
Sender: news@neptune.inf.ethz.ch
Reply-To: brandis@inf.ethz.ch (Marc Brandis)
Organization: Departement Informatik, ETH, Zurich
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In article <1991Feb15.204811.6327@qiclab.scn.rain.com> leonard@qiclab.scn.rain.com (Leonard Erickson) writes:
>
>Do recall that every time you switch *from* protected mode, the CPU gets
>reset. 

This is true for the 286, but not for the 386. On a 20 MHz 386, you can 
switch back to real mode in about 10 microseconds if you trim down the code.
The processor reset is not required, you can just clear a bit in CR0.


Marc-Michael Brandis
Computer Systems Laboratory, ETH-Zentrum (Swiss Federal Institute of Technology)
CH-8092 Zurich, Switzerland
email: brandis@inf.ethz.ch