Article View: comp.os.msdos.programmer
Article #5969Re: Protected mode/Real mode switching
From: DJ Delorie
Date: Fri, 26 Apr 1991 20:17
Date: Fri, 26 Apr 1991 20:17
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1432 bytes
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
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Path: arc1-ca.pugleaf.net!utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!samsung!balrog!ctron.com 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> Sender: news@balrog.ctron.com Reply-To: dj@ctron.com Organization: None whatsoever Lines: 17 Nntp-Posting-Host: bragi