Re: [ros-dev] (Free)DOS subsystem

[Imre Leber]

>  -----Original Message-----
> From: Imre Leber [mailto:[e-mail]]
> Sent: Tuesday, August 29, 2006 02:57 PM
> To: 'ReactOS Development List'
> Subject: Re: [ros-dev] (Free)DOS subsystem
>
>
> >  -----Original Message-----
> > From: Peter Dolding [mailto:[e-mail]]
> > Sent: Tuesday, August 29, 2006 01:33 PM
> > To: 'ReactOS Development List'
> > Subject: Re: [ros-dev] (Free)DOS subsystem
> >
> > Myria wrote:
> > >   I've wanted to write an NTVDM for ReactOS,
> > > but I'm not sure when I'd ever 
> > >  have time.
> > >
> > >  Windows NT's DOS subsystem, NTVDM, is a user-mode program that runs on top 
> > >  of Win32.  It runs DOS programs as Windows processes, using v86 mode to run 
> > >  the programs.  DPMI programs are supported by asking the kernel to allocate 
> > >  LDT segments and running directly.  (If you write a DOS32 program and know 
> > >  the correct addresses, you can call MessageBoxW in user32.dll and it will 
> > >  work.)
> > >
> > >  This differs significantly from DOSBox, which is effectively a machine 
> > >  emulator rather than an API translator.  DOSEmu, in comparison, is 
> > >  essentially the same design as NTVDM but for Linux.
> > >
> > >  FreeDOS in DOSBox works very well, because the FreeDOS kernel is its normal 
> > >  self and is unaware that it's inside a VM.  However, this doesn't work for 
> > >  NTVDM/DOSEmu.  In these, the FreeDOS kernel will need to be heavily 
> > >  modified, particularly because the NT kernel handles file I/O.  Programs 
> > >  inside the virtual DOS environment use illegal opcodes to talk to NTVDM.
> > >
> > >  Melissa
> > >     
> > True  Closest Freedos to Windows NT NTVDM is 
> > http://freedos-32.sourceforge.net/.   Its was newer version under 
> > development.  It could be stalled from 2005.
> >  
> Why?
>
> I never got it. It doesn't seem to add anything new. Nothing that can't be done in
> FreeDOS.
>
> FreeDOS is for all pratical purposes a capable 32 bit system. It can run 32 bit DOS and
> (some) windows programs and it has multithreading (eRTOS), TCP/IP (watt32), etc... . 
>  
Well. Maybe I should have said a 32 bit capable operating system.

>  I think it would not be very difficult to write a
> multitasking DOS extender either (maybe as an extension to cwsdpr0).
>  
But who's ever going to care?

>  If it's because it is running in 32 bit, I am not
> all that convinced that DOS-C can not be ported to 32 bit. It was originally intended to
> run on apple macintosh.
>
> Imre 
Imre

>  
> >  Peter Dolding
> >
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> >
> >  
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