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From: dj@ctron.com (DJ Delorie)
Newsgroups: comp.os.msdos.programmer
Subject: Re: Protected mode/Real mode switching
Message-ID: <1450@balrog.ctron.com>
Date: 26 Apr 91 20:17:09 GMT
References: <1991Apr15.160333.8107@msuinfo.cl.msu.edu> <37390009@hpopd.pwd.hp.com> <3199@bimacs.BITNET> <1448@balrog.ctron.com> <1991Apr26.160753.4754@midway.uchicago.edu>
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In article <1991Apr26.160753.4754@midway.uchicago.edu>, valley@gsbsun.uchicago.edu (Doug Dougherty) writes:
> Certainly the use of LOADALL is akin to usage of the undocumented
> features of the AAD & AAM instructions; "Undocumented DOS" has a very...

As an aside, I have a book by the designer of the 8088/8086 that
documents the "extra" features of the AAD and AAM instructions, so
they're not undocumented.

Also, the fact that the 386 can transition from protected mode to real
mode without a reset means that you can set the segment registers to
arbitrary memory ranges with the MOV ES,AX instruction and a properly
set up GDT.  The OS/2 version that I referred to that used the LOADALL
instruction was 1.0, and I hope they have "fixed" it since then.  They
claimed that there was no 386 version as well.

DJ
dj@ctron.com