From:	Gary Preston <gary AT prestons DOT demon DOT co DOT uk>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Mode 320x400..
Date:	Mon, 12 May 1997 16:32:20 +0100
Organization:	None
Distribution:	world
Message-ID:	<h6bF7DAEgzdzEwr8@prestons.demon.co.uk>
NNTP-Posting-Host:	prestons.demon.co.uk
MIME-Version:	1.0
Lines:	35
To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

 Hi,

 I'm trying to convert some asm code from Zen of graphics garus chap 9
(l9-1.asm) into C. The code is used to set VGA mode 320x400x256 I
translated as follows. 

void Set320x400Mode( void )
{
union REGS r;

  r.x.ax = 0x0013;      /* Set standard 320x200 VGA mode */
  int86( 0x10, &r, &r);

  outportb( SC_INDEX, MEMORY_MODE );
  outportb( SC_DATA, (inportb(SC_DATA & 0xF7 ) | 0x04 ) );
  outportb( GC_INDEX, GRAPHICS_MODE );
  outportb( GC_DATA, inportb( GC_DATA & 0xEF ) );
  outportb( GC_INDEX, MISCELLANEOUS );
  outportb( GC_DATA, inportb( GC_DATA & 0xFD ) );
  outportb( CRTC_INDEX, MAX_SCAN_LINE );
  outportb( CRTC_DATA, inportb( CRTC_DATA & 0xE0 ) );

}

I have'nt cleared the mem yet but it doesn't even produce a garbaged
screen let alone plot a pixel. Have I got the right idea here and where
have I gone wrong? Since I have never used any modes other than 13h
the above code is probably compleat rubbish if so how should I set mode
320x400x256?

Thanks,
-- 
Gary Preston

Turnpike evaluation. For Turnpike information, mailto:info AT turnpike DOT com

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