I don't want to pour fuel on the fire, but in Windows 3.1/95/98/Me, DOS
Windows ARE IN FACT SEPARATE VIRTUAL 8086's. There is no doubt of
this. If you doubt it, write a VxD that dumps out the DTs. All *16-bit*
Windows apps run in a single virtual machine. I do not know how the
32-bit stuff works (personally). But I do know that DOS Windows are still
separate virtual 8086's. The 80x86's implement the virtual 8086 as a
special type of protected mode. They do not have or require the normal
traps and gates you would require to virtualize a 32-bit machine because
the Intel (and compatible) process do all of this in the hardware.
Consult:
http://my.tele2.ee/mtx/i386/chp15-00.htm
or perhaps the horse's mouth:
http://msdn.microsoft.com/library/psdk/win95/chiarc_7p4j.htm
Now, to tell you the truth, I have no idea how NT/2000 does this (probably
not this way, but I really do NOT know), but there is no doubt that DOS
programs on Windows run in separate virtual 8086's. The scenario you
desribe when you"boot to DOS" (boot Windows 95/98/Me without starting the
GUI) is a totally different animal. In that case the processor is in real
mode. It is totally unlike a DOS Window. Show me how you can run two or
more DOS applications simultaneously in that "boot to DOS " state and I'll
buy your assertions.
--
Michael A. Schwarz
[EMAIL PROTECTED]
On Wed, 4 Oct 2000, Drew Northup wrote:
> I find it interesting that you are so convinced of this...., especially if
> the word from the horse's mouth (MicroSoft) says otherwise.......
> As for running LINUX as I client to the Win32API I have seen this once &
> would like to know how it was done.....
> Also...., it must be made clear that when I speak of an OS I speak of a
> true operating system. The Win32API handlers are just well integrated
> clients for DOS. As proof, I would suggest that you try to run a full dos
> mode program in your Windows platform autoexec.bat. Mind you, not the one
> you get in a dos window. I mean the core one that you can get to when you
> boot off of a disk containing only command.com, io.sys, and the
> MS-bootloader code. You will find that the way that the true DOS interface
> works has a lot in common with the "VM" dos interface. If you want to know
> (from a purist point of view) what a DOS window really does, boot off a
> floppy with just command.com, io.sys & the bootloader on it. Then type
> "command.com" at the command prompt. That is what happens in windows when
> you run a dos window. (It is also a major part of what changed in MS-DOS
> since version 3.3.)
> As for the extended VM manager API..., I will remind you that whenever you
> start using an API you start using either libraries or parent programs (so
> that your "executable" runs as a module to something). Thus it is NOT
> REALLY A VM!!!!!
>
> more to follow.......have a class that I am late for.......
>
> Drew Northup, N1XIM
>
>
> > -----Original Message-----
> > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf
> > Of Fred Weigel
> > Sent: Wednesday, October 04, 2000 12:11 PM
> > To: [EMAIL PROTECTED]
> > Subject: RE: Vocabulary
> >
> >
> > They *are* true VM's. The machine being emulated is an 8086,
> > not a 386+. Access to i/o ports can be trapped, access to interrupt
> > vectors, etc. In Windows 3.x, the Window applications run in one
> > VM cooperatively. There is another OS "under the covers" in Windows
> > (not discussing NT here). It is possible to strip off the "Windows"
> > part, and use just the underlying VM OS (not easy, just possible).
> > An interesting hack (and not one I've seen published yet).
> >
> > Another theoretical idea is to augment the Windows VM manager,
> > allowing it to do partial 386+ virtualization. This gets you into the
> > domain covered by NT, with none of the associated headaches.
> > There is enough in the published VM manager documentation to
> > allow this extension. Then, the Linux kernel could be modified
> > to use the extended VM manager API, which gives you Linux
> > cooperating under Windows. Not as polished as Plex86, but it
> > would be easier. I find it interesting that the Linux under Linux
> > folk haven't pursued this. The big problem with this approach is
> > filesystem code, but the UMSDOS filesystem could certainly
> > accomodate the need.
> >
> > Ratboy.
> >
> >
> >
> > ----Original Message Follows----
> > From: "Drew Northup" <[EMAIL PROTECTED]>
> > Reply-To: [EMAIL PROTECTED]
> > To: <[EMAIL PROTECTED]>
> > Subject: RE: Vocabulary
> > Date: Fri, 22 Sep 2000 23:48:29 -0400
> >
> > Yep, you'd be right!!! Which is why I didn't refer to them as
> > true VM's!!!!
> >
> > Drew Northup, N1XIM
> >
> >
> > > -----Original Message-----
> > > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf
> > > Of Nick Behnken
> > > Sent: Thursday, September 21, 2000 11:59 PM
> > > To: [EMAIL PROTECTED]
> > > Subject: Re: Vocabulary
> > >
> > >
> > > Win95 runs all dos apps in a seperate VM in VM86. Win32 apps share the
> > > System VM ... ie the one that is present went dos loads becomes
> > > the system
> > > vm. All other dos vm's are copied from the system vm, but share a
> > portion
> > > of the first 640K of memory. This is why if you use debug from a
> > > dos vm and
> > > overwrite the first 64K of ram. Windows 95/98 crashes..
> > because you just
> > > overwrote the real mode interrupt table.. So much for a true
> > > protected mode
> > > OS ! lol
> > >
> > > Windows NT does not use VM86! The dos emulator is a win32 app
> > written by
> > > Insignia.
> > >
> > > Nick
> > >
> > > ----- Original Message -----
> > > From: "Drew Northup" <[EMAIL PROTECTED]>
> > > To: <[EMAIL PROTECTED]>
> > > Sent: Thursday, September 21, 2000 6:08 PM
> > > Subject: RE: Vocabulary
> > >
> > >
> > > > Yeah....., not only do they say that it is all in one VM, but
> > > that is what
> > > > the Win2k debug team leader said..... to my face. I'll take
> > > his word for
> > > > it!!! As for the MSDN library thing you are probably
> > > right--that thing is
> > > > full of errors!!!
> > > >
> > > > Drew Northup, N1XIM
> > > >
> > > >
> > > > > -----Original Message-----
> > > > > From: [EMAIL PROTECTED]
> > > [mailto:[EMAIL PROTECTED]]On Behalf
> > > > > Of X-Odus
> > > > > Sent:
> > > Thursday, September 21, 2000 11:37 AM
> > > > > To: [EMAIL PROTECTED]
> > > > > Subject: Re: Vocabulary
> > > > >
> > > > >
> > > > > This probably doesnt matter but:
> > > > > http://www.fayle.freeserve.co.uk/95vmm.htm
> > > > >
> > > > > That says that Win95 and all Win32 processes run in the same VM.
> > > > > I remember
> > > > > something in the MSDN library saying differently. But hey
> > who cares.
> > > > >
> > > > > Amy Lear wrote:
> > > > >
> > > > > > From: X-Odus <[EMAIL PROTECTED]>
> > > > > >
> > > > > > > Look up windows architecture it refers to them as virtual
> > > machines.
> > > > > >
> > > > > > I feel obligated to note that in the NT 4.0 terminology, a
> > > > > computer boots from
> > > > > > the system partition, and the OS loads from the boot partition.
> > > > > >
> > > > > > However Microsoft refers to something hardly matters, in many
> > cases.
> > > =>
> > > > >
> > > > >
> > > > >
> > > >
> > > >
> > > >
> > >
> > >
> > >
> >
> >
> >
> > _________________________________________________________________________
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>
>
>