From:	Hans-Bernhard Broeker <broeker AT physik DOT rwth-aachen DOT de>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: Forgive my ignorance....
Date:	7 May 2001 13:52:23 GMT
Organization:	Aachen University of Technology (RWTH)
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mesh <reaver5 AT nospamyahoo DOT com> wrote:
> ...but I'm having a difficult time figuring out what exactly DJGPP is.  I
> mean, I know that it's "a complete 32-bit C/C++ development system for Intel
> 80386 (and higher) PCs running DOS" and all, but does that mean that's it's
> a program or what exactly?  

At the very heart of it, DJGPP is a C runtime environment (i.e. a program
loader and runtime library). 

The more global picture is that DJGPP is a *huge* collection of
programs all using this C runtime environment to do their work,
including a compiler and tools to create further programs of that
kind.

> When I compile a source file, I use the GNU compiler, right?  

To be precise: you use a version of the GNU compiler with DJGPP as
both its "target platform" and it's "host platform". I.e. your GCC
makes programs that use the DJGPP runtime environment to run, and GCC
itself uses the DJGPP runtime environment, too --- it's been compiled
by itself.

> So where does DJGPP come into play?  

It's the interface between your code (as compiled by GCC) and the
operating system.

> Couldn't I just have downloaded gcc from the GNU website and used
> that to compile my source?

Not quite. Downloading GCC there, you get the sources of GCC. To
compile those, you need a working compiler --- but what other compiler
could that be? A chicken-and-egg problem.  And even then, to compile a
program, you need not just GCC (and binutils), but also a C runtime
environment on the target platform. That's where core of DJGPP comes
into the play.

-- 
Hans-Bernhard Broeker (broeker AT physik DOT rwth-aachen DOT de)
Even if all the snow were burnt, ashes would remain.

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