Path: utzoo!attcan!uunet!tut.cis.ohio-state.edu!pt.cs.cmu.edu!b.gp.cs.cmu.edu!Ralf.Brown@B.GP.CS.CMU.EDU
From: Ralf.Brown@B.GP.CS.CMU.EDU
Newsgroups: comp.os.msdos.programmer
Subject: Re: Detecting an 80486
Message-ID: <26a858b9@ralf>
Date: 21 Jul 90 13:29:29 GMT
Sender: ralf@b.gp.cs.cmu.edu
Organization: Carnegie Mellon University School of Computer Science
Lines: 25
In-Reply-To: <1990Jul20.230335.22816@ddsw1.MCS.COM>

In article <1990Jul20.230335.22816@ddsw1.MCS.COM>, andyross@ddsw1.MCS.COM (Andrew Rossmann) wrote:
}In article <315@bally.Bally.COM> pete@bally.UUCP (exilied in my own office) writes:
}>In article <1990Jul19.025150.6150@looking.on.ca> brad@looking.on.ca (Brad Templeton) writes:
}  In my Infoplus program, the 286/386/486 are detected by trapping the
}invalid opcode interrupt, and then trying instructions. For the 486, I use
}XADD DX,DX. This is new on the 486, and exchanges the registers before
}doing the addition.
}  For the 386, I now use MOV EDX,EDX, which is 32-bit do-nothing! (It used
}to use an instruction that read some special registers. This caused major
}problems with most EMS emulators!)
}  For the 286, it tries the SMSW DX instruction (whatever that does.)
}  The code come from a program by Robert Collins, and I just made a few
}changes to fit INFOPLUS (and fix the 386 problem!)

Unfortunately, your program will fail miserably on my system (and about a
million others), because I am running QEMM-386.  QEMM runs in protected mode
with DOS in virtual-86 mode.  Any invalid opcode exception that your
program generated invokes the QEMM exception handler, NOT YOURS.  And the
QEMM exception handler gives the choice of terminating or rebooting.  I
expect similar behavior from 386^Max, CEMM, AllCharge386, MICEMM, ....
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