<html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>DOS and Windows</title><meta name="generator" content="DocBook XSL Stylesheets V1.76.1"><meta name="keywords" content="assembly, assembler, asm, inline, 32-bit, IA-32, i386, x86, nasm, gas, as, as86, yasm, fasm, shasm, osimpa, OS, Linux, Unix, kernel, system, libc, glibc, system call, interrupt, small, fast, embedded, hardware, port, macroprocessor, metaprogramming, preprocessor"><link rel="home" href="Assembly-HOWTO.html" title="Linux Assembly HOWTO"><link rel="up" href="conventions.html" title="Chapter 5. Calling conventions"><link rel="prev" href="conventions.html" title="Chapter 5. Calling conventions"><link rel="next" href="ownos.html" title="Your own OS"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">DOS and Windows</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="conventions.html">Prev</a> </td><th width="60%" align="center">Chapter 5. Calling conventions</th><td width="20%" align="right"> <a accesskey="n" href="ownos.html">Next</a></td></tr></table><hr></div><div class="section" title="DOS and Windows"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="idp445872"></a>DOS and Windows</h2></div></div></div>
<p>
Most DOS extenders come with some interface to DOS services. Read their docs
about that, but often, they just simulate <code class="function">int 0x21</code> and
such, so you do "as if" you are in real mode (I doubt they have more than stubs
and extend things to work with 32-bit operands; they most likely will just
reflect the interrupt into the real-mode or vm86 handler).
</p>
<p>
Docs about DPMI (and much more) can be found on
<a class="ulink" href="http://en.wikipedia.org/wiki/DOS_Protected_Mode_Interface" target="_top">
http://en.wikipedia.org/wiki/DOS_Protected_Mode_Interface</a>).
</p>
<p>
DJGPP comes with its own (limited) <span class="application">glibc</span>
derivative/subset/replacement, too.
</p>
<p>
It is possible to cross-compile from Linux to DOS, see the
<code class="filename">devel/msdos/</code> directory of your local FTP mirror for
metalab.unc.edu; Also see the MOSS DOS-extender from the
<a class="ulink" href="http://www.cs.utah.edu/projects/flux/" target="_top">Flux project</a>
from the university of Utah.
</p>
<p>
Other documents and FAQs are more DOS-centered; we do not recommend DOS
development.
</p>
<p title="Windows and Co.">
<b>Windows and Co. </b>
This document is not about Windows programming, you can find lots of documents
about it everywhere... The thing you should know is that there is the
<a class="ulink" href="http://www.cygwin.com" target="_top">cygwin32.dll library</a>,
for GNU programs to run on Win32 platform; thus, you can use GCC, GAS,
all the GNU tools, and many other Unix applications.
</p>
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