.\" $OpenBSD: vga.4,v 1.15 2007/11/25 17:11:12 oga Exp $
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.\" 	Matthias Drochner.  All rights reserved.
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.Dd $Mdocdate: November 25 2007 $
.Dt VGA 4
.Os
.Sh NAME
.Nm vga
.Nd VGA graphics driver for wscons
.Sh SYNOPSIS
.Cd "vga0 at isa?"
.Cd "vga* at pci?"
.Cd "wsdisplay* at vga?"
.Sh DESCRIPTION
This driver handles VGA graphics hardware within the
.Xr wscons 4
console framework.
It doesn't provide direct device driver entry points but makes its
functions available via the internal
.Xr wsdisplay 4
interface.
.Pp
The
.Nm
driver supports multiple virtual screens on one physical display.
The screens allocated on one display can be of different
.Dq types ,
where a type refers to various display properties.
The type is determined at the time the virtual screen is created and can't
be changed later.
Screens are either created at kernel startup (then the default type is used)
or later with help of the
.Xr wsconscfg 8
utility.
.Pp
Currently, the following screen types are supported:
.Bl -hang
.It 80x25
This is the standard VGA text mode with 80 columns and 25 rows.
16 different colors can be displayed at the same time.
Characters are 8 x 16 pixels large, and a font consists of 256 characters.
A built-in font of this size is always present on a VGA card.
It's also possible to use a downloaded font instead.
.It 80x25bf
A modified version of the previous.
It only allows 8 colors to be displayed.
In exchange, it can access two fonts at the same time, so that 512
different characters can be displayed.
.It 80x40
A text mode with 80 columns and 40 rows.
Similar to the standard mode, 16 colors and 256 characters are available.
Characters are 8 x 10 pixels large.
For this mode to be useful, a font of that character size must be downloaded.
.It 80x40bf
A modified version of the previous.
It only allows 8 colors to be displayed.
In exchange, it can access two fonts at the same time, so that 512
different characters can be displayed.
.It 80x50
A text mode with 80 columns and 50 rows.
Similar to the standard mode, 16 colors and 256 characters are available.
Characters are 8 x 8 pixels large.
For this mode to be useful, a font of that character size must be downloaded.
.It 80x50bf
A modified version of the previous.
It only allows 8 colors to be displayed.
In exchange, it can access two fonts at the same time, so that 512
different characters can be displayed.
.It 80x24
A variant of the
.Dq 80x25
screen type which displays 24 lines only.
It uses the standard 8x16 VGA font.
This mode might be useful for applications which depend on closer
DEC VT100 compatibility.
.It 80x24bf
A modified version of the previous.
It only allows 8 colors to be displayed.
In exchange, it can access two fonts at the same time, so that 512
different characters can be displayed.
.El
.Pp
The
.Nm
driver can display fonts of the original IBM type and ISO-8859-1 encoded fonts.
As an experimental feature, the
.Dq higher half
fonts of the former
.Ox Ns /i386
pcvt driver distribution can be used too if
.Ic option WSCONS_SUPPORT_PCVTFONTS
was set at kernel compile time.
This is only useful with the
.Dq *bf
screen types; a font containing the ASCII
range of characters must be available too on this screen.
.Sh SEE ALSO
.Xr intro 4 ,
.Xr isa 4 ,
.Xr pcdisplay 4 ,
.Xr pci 4 ,
.Xr wscons 4 ,
.Xr wsdisplay 4 ,
.Xr wsconscfg 8 ,
.Xr wsfontload 8
.Sh BUGS
Only a subset of the possible text modes is supported.
.Pp
VGA cards are supposed to emulate an MDA if a monochrome display is connected.
In this case, the device will naturally not support colors at all, but
offer the capability to display underlined characters instead.
The
.Dq 80x25bf ,
.Dq 80x40bf ,
.Dq 80x50bf ,
and
.Dq 80x24bf
screen types will not be available.
This mode of operation is not tested.