Re: Basic Text Mode (was: Re: Question about SysRq)

[Boris Pisarcik <boris@acheron.sk>]

> It is a very good idea, and to implement quite easy. You just do have to
> diff between three types of video cards (MDA, MGA and HGC vs. CGA and AGA vs. EGA+).
> Then you do direct register writes. For the HGC I did it recently in a DOS proggy
> which switched from text to gfx and back. I had a TSR which simulated a gfx BIOS.
> Only problem is, I lost the source. But I could rewrite and test it on request.
> I even would put it under GPL for the kernel (normally this is a no-no for me),
> just ask me. I will write it in NASM then because I can't the AT&T syntax.
> For non-i386 Platforms I do not know about this topic. (IIRC the Apples didnt
> even have a text mode)
> Maybe I could look up the EGA register values somewhere.

The hardware part of mode restoring could really be done the register way and
may be interesting - i did code a lot in dos and this is what i did too, 
if i had experience with register programming and vga(..). Mostly i skipped
this arena, because i have had information about vga registers just enough
to damage monitor, so rather used VESA for video stuff :)
But i think only this way should break some internal state of console or
what driver. 

Thanks for the willingness, thought. I read from the thread - James Simmons,
console developer, is working on it, so you may eg. ask to cooperate with him,
he surely has a lot of ideas of text/vga switching in linux.

Cheers                                                               B.