[ros-dev] (Free)DOS subsystem

[Imre Leber]

>-----Original Message-----
>From: Imre Leber [mailto:imre.leber at telenet.be]
>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:oiaohm at bluebottle.com]
>>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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