Re: New VGA console coming

[Steffen S. <se...@ph...>]

James Simmons wrote:

>    Now for the next step in the evolution of the console system. Well I
> made a discovery today. Their exist vga cards (JEGA, AX-VGA) that can
> display asian characters. I also discovered some old BIOS calls that might
> lead to figuring out if double byte fonts could be supported. The BIOS
> call int 10h, ah=18h, al=0,1 which can get/set a font pattern. This leads
> to me to believe it might be possible for VGA to support double byte
> fonts. This of course would mean a rethinking of how the shadow buffer
> should be done. Any ideas anyone?

Designing the KGI console system, I had a similar problem. The solution
I have implemented is not to make any assumption about how the graphics
card stores the displayed text. Basically it works this way:

The console layer handles the glyph information to be displayed using full
UNICODE-2.0 (or it's successor, the ISO norm for 32bit character codes).
Using the font and attribute information, this is translated into a
font-specific code, which is stored in the shadow buffer using a pattern
defined by the graphics driver only. Then the graphics driver does the
rendering from the shadow buffer, it never gets involved with the 
glyph-code -> font position translation. This way it is up to the graphics
driver, which attributes and how many font characters it supports. 

However, due to the current (VGA compatible) shadow buffer layout used by
KGI only 256 font characters are possible.

Hope this is of help,

			Steffen

_______________________________________________________________________________
Steffen Seeger                              mailto:se...@ph...
TU-Chemnitz                                      http://www.tu-chemnitz.de/~sse