Date:	Thu, 12 Aug 1999 16:12:12 +0200
From:	Hans-Bernhard Broeker <broeker AT physik DOT rwth-aachen DOT de>
Message-Id:	<199908121412.QAA17347@acp3bf.physik.rwth-aachen.de>
To:	djgpp AT delorie DOT com
Subject:	Re: vga vs VESA with gnuplot
Newsgroups:	comp.os.msdos.djgpp
Organization:	RWTH Aachen, III. physikalisches Institut B
X-Newsreader:	TIN [version 1.2 PL2]
Reply-To:	djgpp AT delorie DOT com

In article <199908111957 DOT OAA21982 AT darwin DOT sfbr DOT org> you wrote:
> I'm using the djgpp port of gnuplot---it's very nice.  The readme.dj2
> doc says that two options (among others) for the GRX20DRV environment
> variable (used by the GRX-2.3 graphix library) are

> SET GRX20DRV=VESA  gw <width> gh <height> nc <colors>

> SET GRX20DRV=stdvga  gw <width> gh <height> nc <colors>

> OTOH the `set terminal' command in gnuplot accepts `svga' but
> does not recognize `VESA'.

You're confusing two kinds of 'set' commands, it seems.

The 'set terminal' command inside gnuplot is independent of what you
set GRX20DRV to. For using the graphical screen in DJGPP-compiled
gnuplot, you should always 'set term svga' (it's the default, too).
'set term svga' in gnuplot will activate use of the GRX library.

From there on, it's an issue of configuring GRX for your graphics
card. This is done by environment variables, which can be 'set' at the
command line prompt or in autoexec.bat, i.e. outside gnuplot. If you
have DJGPP installed, you can also put a line into DJGPP.ENV, to save
environment space for non-DJGPP programs. But be careful not to damage
your DJGPP.ENV. It's a bit fragile.

The single most important environment variable for configuring GRX is
'GRX20DRV'. For most cards

	SET GRX20DRV=VESA gw 800 gh 600 nc 256

is a good starting point that should work.  For details, you'll want
to consult the GRX documentation. There's to much to this to explain
all of it in a newsgroup answer.

> Can someone explain to me the difference between stdvga and VESA
> (I know what the acronyms stand for :), and when one would be
> preferred over the other?

For all 'usual' cases, use VESA and never look back. Only if VESA
doesn't work, you'll want to investigate the alternatives.

'stdvga' is the ultra-conservative driver. It should work on any card
calling itself VGA compatible or higher, i.e. practically every card
built since 1990 or so. It won't offer more than 320x200x256 or
640x480x16, though, which is painfully bad for modern standards. So
you probably won't want to use this except as a fallback solution,
where VESA doesn't work.


--
Hans-Bernhard Broeker (broeker AT physik DOT rwth-aachen DOT de)
Even if all the snow were burnt, ashes would remain.

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