Date: Sat, 25 Mar 2000 22:58:12 -0500
Message-Id: <200003260358.WAA25410@mescaline.gnu.org>
From: Eli Zaretskii <eliz AT gnu DOT org>
To: djgpp AT delorie DOT com
In-reply-to: <052897bc.015fb25e@usw-ex0110-076.remarq.com> (message from
	Bernhard Stiftner on Sat, 25 Mar 2000 09:18:41 -0800)
Subject: Re: Multitasking: executing some EXE-files (nearly) simultaneously
References:  <052897bc DOT 015fb25e AT usw-ex0110-076 DOT remarq DOT com>
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   A very interesting (=difficult to impossible) topic of
   programming with (MS)-DOS is multitasking. My idea was to
   execute two or more EXE-files (nearly) at the same time by
   reading them manually into RAM, interpreting&executing some
   commands, saving all the registers into RAM, then switching
   to the other application, restoring its previously saved
   CPU registers and executing some commands and so on...
   Does anybody have any idea how this could be made work?

The DJGPP debug support does something similar to load the debuggee
and jump between it and the dbugger's own code.  It's messy, but it
does work.  You could begin by studying how does the DJGPP debug
support does this.  Type "info libc alpha run_child" to start.  The
docs is minimal, so you should be prepared to read the sources and ask
questions.