VGA(3)							     Library Functions Manual							    VGA(3)

NAME

       vga - VGA controller device

SYNOPSIS

       bind #v /dev

       /dev/vgactl
       /dev/vgaiob
       /dev/vgaiow
       /dev/vgaiol

DESCRIPTION

       The  VGA  device  allows  configuration of a graphics controller on a PC.  Vgactl allows control over higher-level settings such as display
       height, width, depth, controller and hardware-cursor type.  Vgaiob, vgaiow and vgaiol allow  control  over  individual  8-bit,  16-bit  and
       32-bit x86 I/O-ports respectively, such as those used to implement configuration and setup registers on a VGA controller card.  These func-
       tions are normally carried out by vga(8).

       Writes to vgactl are of the form `attribute value'.  Valid attributes are

       size   value is 'XxYxZ' , where X, Y and Z are numbers that tell the kernel the width and height of the screen in pixels and the number	of
	      bits per pixel.

       type   tells the kernel which type of controller is being used, mainly to enable the correct code for display-memory bank switching at res-
	      olutions greater than 640x480x1. The names vga, clgd542x, et4000, mach32, and s3 are supported for value.

	      Note that this list does not indicate the full set of VGA chips supported. For example, s3 includes the 86C801/5, 86C928, Vision864,
	      and Vision964.  It is the job of vga(8) to recognize which particular chip is being used and to initialize it appropriately.

       hwgc   tells the kernel to use a particular type of hardware graphics cursor.  Bt485hwgc, et4000hwgc, s3hwgc and tvp3020hwgc, are currently
	      recognized values.  A value of off reverts to using the software cursor.

       Reading vgactl returns the current settings, one per line.

EXAMPLES

       The following reverts to using the software graphics cursor

	    echo -n 'hwgc off' >/dev/vgactl

       Sample code to read an x86 8-bit I/O port

	    uchar
	    inportb(long port)
	    {
		 uchar data;

		 if(iobfd == -1)
		      iobfd = open("#v/vgaiob", ORDWR);

		 seek(iobfd, port, 0);
		 if(read(iobfd, &data, sizeof(data)) != sizeof(data))
		      error("inportb(0x%4.4x): %r0, port);
		 return data;
	    }

SOURCE

       /sys/src/9/pc/devvga.c

SEE ALSO

       vga(8)

BUGS

       There should be some restriction on the range of valid ports.

       There should be support for the hardware graphics cursor on the clgd54[23]x VGA controller chips.

       The hardware graphics cursor on the et4000 does not work in 2x8-bit mode.

																	    VGA(3)