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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> > http://www.reactos.org/mailman/listinfo/ros-dev
>
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