Date: Wed, 15 Jan 1997 18:43:17 +0200 (IST)
From: Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
To: "Maan M. Hamze" <mmhamze AT mail DOT utexas DOT edu>
cc: djgpp AT delorie DOT com
Subject: Re: EMX, RSX, CWSDPMI, DJGPP trivia!
In-Reply-To: <01bc0263$7dac6840$7ccc5380@maan-m.-hamze>
Message-ID: <Pine.SUN.3.91.970115183554.15708A-100000@is>
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII


On 14 Jan 1997, Maan M. Hamze wrote:

> 1.  What is exactly EMX?  The regular port uses EMX as a DOS-extender, but
> the confusion arises out of RSX.

EMX is a DOS-extender.

> 2.  RSX is a DOS-extender too, so what is the difference between EMX and
> RSX?

RSX needs DPMI services to enter protected mode; EMX supports other 
methods (VCPI and maybe Int 15h, raw XMS etc.).

> 3.  RSX, as used through RSXNT and NT09, needs a DPMI memory manager like
> CWSDPMI in DOS Mode.  But EMX does not.  What am I missing?

EMX does more work.  It uses VCPI to enter protected mode and does all 
the translation services required to issue real-mode interrupts (DOS, 
BIOS etc.) by itself.  RSX relies on the DPMI host to do most of this.

> 4.  What is the difference between the regular EMX port and DJGPP for DOS
> apps?  Is EMX a 16-bit dos-extender?

No, it's a 32-bit extender, but different from DJGPP.  The fine details 
of the binaries are also different (e.g., EMX uses AOUT as far as I know, 
not COFF, the startup code is entirely different, etc.).

> Do EMX DOS apps run in real or protected mode?

Protected mode of course, otherwise you don't need a DOS extender at all, 
right?

> So my question is, is it possible to use Graphics and windowing libraries
> for DJGPP (such as grx, mikallig, mtws, and sound libs etc...)
> with the DOS apps created using RSXNT and NT09?

I don't know.  Anybody?