From: zmbenhal@netcom.com (Zeyd M. Ben-Halim) Subject: Re: How to switch back to VGA-text from SVGA-text mode??? Date: Fri, 26 Mar 1993 21:04:34 GMT
In article <1993Mar26.171516.3195@prime.mdata.fi> kennu@mits.mdata.fi (Kenneth Falck) writes:
>In article <1993Mar24.224133.12392@primerd.prime.com> cummings@hammer.prime.com (Kevin Cummings) writes:
>>Since video hardware varies from machine to machine (and card to card)
>>the only "portable" method of doing this is for the system to provide a
>>common interface to the video hardware. This method is currently the INT 14
>>code in your video BIOS. Sadly, OSes like LINUX do not use any of the BIOS
>>code in your machine. Therefore, you need a program to do the work for you.
>
>You know, this is something I've been wondering for some time now.
>Why exactly is it that BIOS calls can't be made under Linux?
Because nobody has bothered to write to interrupt handlers in protected-mode
to run real-mode code. It certainly CAN be done, only those who want it don't
have enough knowledge about 386 programming, whilst those who know have a
religious thing about not supporting the BIOS :-)
>I think I recall someone describing the details many months ago,
>but I didn't pay too much attention until I recently got an
>ET4000 and wanted to switch between modes 132x44 and 80x50 without
>rebooting all the time.
>
>I suppose I should get a reference sheet or something and start
>hacking... There's a doc in the vgalib distribution but it's very
>terse. Furthermore I have no documentation of how to use ioperm()
>and stuff like that. :-/
You could use code similar to that in vgalib to switch text modes. Just add
register values for such modes.
>>--
>>Kevin J. Cummings ComputerVision Services
>>cummings@kjc386.framingham.ma.us cummings@primerd.Prime.COM
>
>--
>kennu@mits.mdata.fi
>Tired of DOS? Try Linux, a free UNIX-clone for the 386/486 by Linus Torvalds.
>Read comp.os.linux (or ask me by email if you like) for more information.