Date: Mon, 27 May 1996 13:16:45 +0200 (IST)
From: Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
To: Samuel Vincent <svincent AT cs DOT sonoma DOT edu>
Cc: "Jeremy W. Deats" <jeremy AT neosoft DOT com>, djgpp AT delorie DOT com
Subject: Re: Simple mode 13h stuff... why doesn't this work?
In-Reply-To: <Pine.SUN.3.90.960527031335.29517A-100000@zippy>
Message-Id: <Pine.SUN.3.91.960527131315.9922B-100000@is>
Mime-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII


On Mon, 27 May 1996, Samuel Vincent wrote:

> > The villain is the following line:
> >  
> > > unsigned char *video_buffer = (unsigned char *)0xe00a0000L;
> > 
> 
> Well..  actually, that's not even the address he really wants
> to address. :)   That's the 0xe00a0000'th byte from the beginning
> of your djgpp program's data segment.  (Which most likely isn't in 
> existence unless you've allocated a HUGE amount of memory. ;)

Not necessarily true, since memory mapping registers of the CPU might be 
set up in such a way that the above address is mapped to the video RAM.  
In fact, DJGPP v1.x did just that, which probably is the cause that code 
was ever written in the first place.  Under DPMI this cannot be done, 
because the DPMI host takes over the memory mapping, so in DJGPP v2 this 
doesn't work.