From:	Brian Hogg <bhogg AT worldchat DOT com>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: Protected Mode
Date:	8 Nov 1997 05:04:57 GMT
Organization:	WorldCHAT(tm) Internet Services
Lines:	32
Message-ID:	<640rtp$oq6$1@news1.worldchat.com>
NNTP-Posting-Host:	as-1-p24.wchat.on.ca
To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

BlueShade <blueshade AT mailexcite DOT com> writes:
> I have done a lot of programming in DJGPP, and I still don't get what
> the heck the difference is between protected mode and real mode, and

Differences? There's plenty.  The one major thing is memory is used,
without needed to know which type it is, and it's done automatically.
You can use extended, expanded, XMS, EMS, conventional and virtual (disk)
without need to know, or caring about, what type it really is.  There
are exceptions, like timer interrupts and things, that you need to know
what type your using (since if a disk swap occurs during an interrupt,
your messed :)).  You can always turn off disk access (virtual mem) if
you know you don't need it, or you want to make sure you won't use it.

If I'm wrong about anything, someone correct me please :)

> what you need to do to write code in protected mode.  Got any
> suggestions as to where I could look?
With DJGPP DOS (and I think all DJGPP ports..), flat pmode is automatically
put in.  Thing is you need CWSDPMI or some similar DPMI server to run
these applications in the 32bit protected mode.  CWSDPMI is free and
if you already made and ran programs using DJGPP, you must've been using
it (Or something else similar, like windows).

If you need a brief description, and links to FAQ's, addons and the like,
check out:

http://brennan.home.ml.org/djgpp/

An excellant source of info!

Thanks,
Brian

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