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From: toma@tekgvs.LABS.TEK.COM (Tom Almy)
Newsgroups: comp.sys.ibm.pc.misc
Subject: Re: VGA 256 color modes
Message-ID: <8059@tekgvs.LABS.TEK.COM>
Date: 6 Sep 90 18:38:32 GMT
References: <3942@bingvaxu.cc.binghamton.edu>
Reply-To: toma@tekgvs.LABS.TEK.COM (Tom Almy)
Organization: Tektronix, Inc., Beaverton,  OR.
Lines: 40

In article <3942@bingvaxu.cc.binghamton.edu> consp12@bingsuns.cc.binghamton.edu (David Hoelzer) writes:
>Ok..  Here's a good one..  I keep hearing about all of these
>undocumented VGA modes..  Does anyone out there  have any documentation
>on any of these modes.  Especially a hiresolution 256 color mode and the
>43 line mode..

I don't know about the hires 256 color mode, but the 43 line mode (or better
50 line mode) are documented:

Do this for 43 lines:
	mov	ax, 1201H	; select 350 scan lines
	mov	bl, 30H	
	int	10H

Then do this for either 43 or 50 lines:
	mov	ax, 0003H	; select mode 3, and sets scan lines
	int	10H
	mov	ax, 1112H	; load 8x8 font
	mov	bl, 0
	int 	10H
	mov	ax, 1200h	; load better printscreen routine
	mov	bl, 20h
	int	10H

To return to standard mode,

	mov	ax, 1202h	; restore 400 lines (if was in 43 line mode)
	mov	bl, 20h		; otherwise you get EGA resolution 80x25
	int	10h

	mov	ax, 0003h	; select mode 3
	int	10h



Tailor as necessary for high level languages.
						
Tom Almy
toma@tekgvs.labs.tek.com
Standard Disclaimers Apply