X-Authentication-Warning:	delorie.com: mailnull set sender to djgpp-bounces using -f
Date:	Tue, 11 Dec 2001 09:47:52 +0200 (IST)
From:	Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
X-Sender:	eliz AT is
To:	Derek <djny AT flashmail DOT com>
cc:	djgpp AT delorie DOT com
Subject:	Re: Does LWP need a coprocessor?
In-Reply-To:	<IFfR7.260$q13.334295@news.uswest.net>
Message-ID:	<Pine.SUN.3.91.1011211093830.19A-100000@is>
MIME-Version:	1.0
Reply-To:	djgpp AT delorie DOT com
Errors-To:	nobody AT delorie DOT com
X-Mailing-List:	djgpp AT delorie DOT com
X-Unsubscribes-To:	listserv AT delorie DOT com

On Mon, 10 Dec 2001, Derek wrote:

> > In any case, I suggest you set 387=n in the environment and try again.
> 
> I'm a newbie. What exactly does it mean to set that in the environment, and
> what does it accomplish? Did you mean 386=n?

Edit your AUTOEXEC.BAT (create it if it doesn't exist) and add this
line somewhere:

set 387=n

Then save AUTOEXEC.BAT and reboot.  Now try running the floating-point
programs again and see if they work.  They should.

> > It sounds like you could use a timer instead.
> 
> I think I would prefer this. Would it work with my incapable pc?

Yes, they would.

> > Note that in DJGPP, signal delivery is delayed when the program is not
> > in protected mode (like when it's in a DOS system call).
> 
> How much is it delayed by?

Until the program is back in protected mode.  Can be quite long in
some cases, e.g. if the program is stuck in a DOS call which awaits
input from keyboard.

> How do you run a program in protected mode?

Sorry, I didn't realize that you have a lot to catch up about DJGPP
(I thought, since you mess with timers and multitasking, that you
already knew the basics).

DJGPP programs run in protected mode by default, but they need to
switch to real mode when they issue DOS or BIOS calls, since DOS and
BIOS run real-mode code which will crash the machine instantly if you
try to run it in protected mode.

For more details, I suggest to read this (slightly outdated)
introduction to DJGPP:

  http://www.delorie.com/djgpp/doc/eli-m17n99.html

> Does DOS system call mean telling it to execute the program at the
> command prompt?

DOS system calls are functions of Interrupt 21h, a software interrupt
that allows DOS programs to do things like disk I/O, memory
management, system clock management, etc.  Every program that reads or
writes disk files or displays something on the screen usually needs to
issue some DOS calls.

- Raw text -