Re: LoadAll?

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Article #21897

#21897

From: Mark Robert Thorson
Date: Sun, 31 Dec 1989 20:22

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What Tim implied, but didn't say explicitly, was that switching to protected
mode on a 286 is a one-way trapdoor.  Can't get back to real-address mode.
This is why MS-DOS on the 286 must run in real mode (8086 compatibility mode)
because it needs to run 8086/8 binaries.

On the 386, this isn't a problem, because you can switch back to real-mode
after loading the "invisible" part of the segment registers.  This lets you
set up addressing beyond the first 1 Mbytes of address space.

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Message-ID: <25528@cup.portal.com>

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arc1-ca.pugleaf.net!utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!cs.utexas.edu!samsung!brutus.cs.uiuc.edu!apple!fox!portal!cup.portal.com!mmm

References: <597@unmvax.unm.edu> <25493@cup.portal.com>

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Path: arc1-ca.pugleaf.net!utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!cs.utexas.edu!samsung!brutus.cs.uiuc.edu!apple!fox!portal!cup.portal.com!mmm
From: mmm@cup.portal.com (Mark Robert Thorson)
Newsgroups: comp.arch,comp.misc
Subject: Re: LoadAll?
Message-ID: <25528@cup.portal.com>
Date: 31 Dec 89 20:22:53 GMT
References: <597@unmvax.unm.edu> <25493@cup.portal.com>
Distribution: usa
Organization: The Portal System (TM)
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