From: Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
Newsgroups: comp.os.msdos.djgpp
Subject: Re: Multitasking: executing some EXE-files (nearly) simultaneously
Date: Sat, 01 Apr 2000 15:15:35 +0200
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To: djgpp AT delorie DOT com
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Bernhard Stiftner wrote:
> 
> I have now come to a solution of the multitasking problem.
> I've written a interrupt-driven "multitasking" system for
> DOS; here's how it works [it's quite primitive...]
> -the multitasking system installs some interrupt funtions:
>  one adds a process, and another one executes all processes
> -every process (can be in another EXE-file) gives his main
> function address to the "add" interrupt function and
> executes the "execute all processes" function every time
> it's idle.
> 
> My only problem is that I wrote this stuff in Turbo Pascal
> for real mode (good old stuff!), and I don't know if it's
> possible to get this working under 32-bit protected mode in
> GNU C.

Sorry to disappoint you, but this is almost impossible in the DPMI
environment.  The problem is that the DPMI spec explicitly forbids you from
switching stacks in a hardware interrupt handler.  But without switching
stacks your multitasked programs cannot do anything useful.