From:	Charles Sandmann <sandmann AT clio DOT rice DOT edu>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: Generate real-mode 386 DOS executables?
Date:	Sat, 08 Feb 2003 10:53:01 CST
Organization:	Rice University, Houston TX
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Message-ID:	<3e4535ed.sandmann@clio.rice.edu>
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>  The question remains: is DJGPP really for MS-DOS? 

Certainly.

> If so, then I should be able to make 16-bit INT 21h DOS function calls. 

You can.  info libc alpha

see int86, intdos ... 

For interrupts which are not extended, see __dpmi_int

The source for int86 is also available, so can be easily modified if
something is missing.  You could contribute your modifications back if
there is something you feel should be supported.

However, you should typically not need to make Int 21h calls - use
a standard C function instead for portability.

> If I cannot make such calls, it is really not DOS-compliant. 
> So which is it?

I've never seen a document from any standards body about "DOS-compliant".
Each company which made compilers did their own proprietary things.
DJGPP tries to be compatible with both TCC/BCC/MSC - but it's a 
different environment.  There is no "far" - and a 32-bit application 
running in extended memory can't always guess what you want done in
a 16-bit world.

If your code is too heavily dependent on a particular vendor's 
compiler extensions, you will either need to stick with that vendor or
modify your code to be more standard.

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