Date: Sat, 31 Aug 1996 00:00:15 -0400 (EDT) From: Jim Durham <durham@durham> To: sos@freebsd.org Cc: regnauld@tetard.glou.eu.org, hackers@freebsd.org Subject: Re: Specs on a Hitachi CM2085me monitor anybody ?? Message-ID: <Pine.BSF.3.91.960830235011.7333B-100000@w2xo.pgh.pa.us> In-Reply-To: <199608300650.IAA13048@ra.dkuug.dk>
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On Fri, 30 Aug 1996 sos@freebsd.org wrote:
> > > should do it by makeing an extra BIOS rom whith the needed code
> > > in it, at let it register AFTER the std video BIOS has done its trick.
> > >
> > >
> > Hmmm... where would you plug it in?
>
> Maybe in an empty bootprom socket on a netcard :)
>
> > I wasn't aware that you could replace the video mode set routines
> > in the BIOS with code from another ROM, as you do with drivers, etc.
>
> You can do all kinds of nasty things like this i a PC architecture
> that is exactly why its such a pain in the a...
>
> > Just where does syscons.c start functioning in the boot process? What
> You would get output from where syscons takes over, that is after
> the first call to scinit. In effect it would look like what you get
> from a dmesg. You would miss everything up to that point. You could
> also hack the boot manager to do resonable things to you video
> mode, then you would be in business even earlier...
>
That might not be all bad. Hacking the bios is certainly better, but
having all the Unix boot messages would solve most problems, except
hardware ones.
If you wanted to hack some BIOS code, I guess you could probably use an old
MFM disk controller with a rom on board and just unplug or otherwise
disable all the controller chips and just use it for a ROM card... or
any old controller card that had a ROM on board. I guess you'd want
a 16 bit card. (I have a ton of old 8 bit HD controllers 8-) ).
How hard would it be to find the mode set in the BIOS roms themselves?
I know there's a High and Low rom and all that (I've hacked a little
on an old AT bios). Would it be possible to recognize the mode setting
values in the ROM without the source? That would be a cleaner job than
hanging another ROM in there, but no nearly as portable!
Jim Durham
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