Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!wuarchive!usc!apple!oliveb!olivee!swirsky
From: swirsky@olivee.olivetti.com (Robert Swirsky)
Newsgroups: comp.unix.i386
Subject: Re: VP/ix and Merge instruction sets (Was: Re: Can protected mode...)
Message-ID: <51492@oliveb.olivetti.com>
Date: 27 Nov 89 18:30:28 GMT
References: <256D58FD.14619@maccs.dcss.mcmaster.ca> <128383@sun.Eng.Sun.COM> <16784@nuchat.UUCP> <1782@crdos1.crd.ge.COM>
Sender: news@oliveb.olivetti.com
Reply-To: swirsky@olivee.UUCP (Robert Swirsky)
Organization: Olivetti ATC; Cupertino, Ca
Lines: 11

One thing many people don't realize is that the 32-bit arithmetic
instructions *are* available even in REAL and virtual 8086 mode. All
you have to do is put the operand size prefix 0x66 in front of
a math instruction.

Look in any good 80386 programming book for more information.

Of course many programs that expect the computer to be in REAL mode
will still have problems in virtual 8086 mode. For example, if
a program attempts of modify the CR registers, or to switch to 
protected mode, it would fail in virtual-8086 mode (and therefore VP/IX).