From: Michael Feldman <mfeldman AT seas DOT gwu DOT edu>
Subject: Re: fast text screen access
To: eliz AT is DOT elta DOT co DOT il (Eli Zaretskii)
Date: Wed, 21 Dec 1994 18:15:12 -0500 (EST)
Cc: steve AT prd DOT co DOT uk, djgpp AT sun DOT soe DOT clarkson DOT edu

> 
> > I'm in the process of porting from BCC, and there is a just
> > perceptible latency in painting the screen with menus when, using
> > assembler routines and direct access to video memory, they used to
> > flash up apparently instantly.

We have had similar problems.
> 
> DJGPP has all the text-mode screen access functions that BCC
> offers.  Do you see that latency when you use the same
> functions the original BCC-compiled program used?  

No. The Borland version is much faster. Perhaps the difference in the
perceived screen paining speed is due to slower vs. faster machines.
On my 386-33, there is a noticeable difference between the two.

> I did
> such a port awhile ago, and found DJGPP library functions
> no slower then BCC's, except in DPMI mode.  Do you run your
> program in DPMI mode?  If so, and if you don't run under
> Windows' DOS box, put ``nodpmi'' into your GO32 environment
> variable, and you will see much faster screen writes.

Does one need nodpmi even with emm386 set to noems?
> 
> Btw, does anybody on the list know why in DPMI mode screen
> accesses are so much slower?
> 
I'm curious too. Since version 2 will be exclusively DPMI, it'll
be an issue for many of us.

Mike Feldman