Sender: vheyndri AT rug DOT ac DOT be Message-Id: <340A90A4.5BA0@rug.ac.be> Date: Mon, 01 Sep 1997 11:53:40 +0200 From: Vik Heyndrickx Mime-Version: 1.0 To: Eli Zaretskii Cc: djgpp workers Subject: Re: _dos_ds segment limit References: Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Precedence: bulk Eli Zaretskii wrote: > > On Fri, 29 Aug 1997, Vik Heyndrickx wrote: > Does a program that calls `stat', or `fstat', or `getmntent' > considered ``normal''? If so, they all access internal DOS data > structures which are outside the above-mentioned areas. They could be > also either below or above the 640K mark, depending on how did the > host machine load DOS. Yes, DJ already pointed out to me that we can't really live without _dos_ds. Beside the things I called, also structures offered by TSR and the BIOS should be accessible, and since those usually don't reside in fixed places we need one general DOS selector. > No matter how many safe functions would you ad to the library, people > will always want The Fastest Way Ever. I don't see anything wrong in > using farptr functions for accessing any address in the first MB. I won't take people's toys, but offering a safe alternative. E.g. limiting access to the TB through a selector could prevent a lot harm. > What happened to the video RAM access speed survey you were > conducting, btw? I don't think I saw the results. Did I miss > something? Well, no, I didn't publish the results as such. Because I didn't get any report from someone who had a 32-bit video access problem and I bought in the meantime a new computer I "forgot" all about it. Results: - on very slow computers (386SX) or video hardware (slow VGA, old Hercules, ...), 32 bit goes as fast as 16 bit! - on fast computers and video hardware, results vary, from factor 1 to factor 2 speed up. Since text mode output doesn't really put high requirements on performance, it wouldn't be any problem at all to change it from 32 to 16 bits. - Fasted systems are more than 100 times quicker than slowest! Ofcourse all based on reports I got. -- +----------------+ | Vik Heyndrickx | +----------------+