From mboxrd@z Thu Jan  1 00:00:00 1970
Date: Wed, 15 Nov 1995 00:43:24 -0500
From: Kenji Okamoto okamoto@earth.cias.osakafu-u.ac.jp
Subject: a silly question....8 bit color supprted in 386 vga?
Topicbox-Message-UUID: 349da0e4-eac8-11e9-9e20-41e7f4b1d025
Message-ID: <19951115054324.WAzeZFDAfJyVD-h-hWe3Pxrv82X3qCcEwh5Ypq9x4t4@z>

> > 
> > I'm using et4000, att20C490-85, ics2494a set.
> > This works fine for 1024x768x1i as I reported.   However, after I set 
> > my "MACHSPEED VGA 1600" card to 1024x768x8i (14" older display), very
> > atrange behaviors I'm seen.   8-1/2 runs ok, and displays b/w background
> > on the display.   Then, I tried New command, and located the terminal
> > emulater area by mouse, then, nothing came up with.
> > 
> > Is the 8 bit color mode is supported on this assembly?
> > What kinds of colors should I see, if I set it as 1024x768x8?
> 
> If I choose 640x480x8, I can see color image....

Further trying revealed follows:

conditions:   BIOS shadow is enabled for VGA (C0000-C7FFF).
             my terminal has only 8MB memory, and older low frequency VGA
             monitor (up to 45 KHz horizontal frequency).

640x480x1:   Of course, no problem.  ^_^
640x480x8:   No problem to display color images such as dna.3c, table.3c etc.
800x600x8:   no problem for smaller size of color image.  For larger image,
             9v says "Can't read image".
1024x768x1i: every thing works fine without color. :-)
1024x768x8i: 8-1/2 comes up, but terminal emulater box cannot be
             set.   I can see and set only rubberband.  After its setting,
             it disappeares.

If BIOS shadow is set disabled, things are miserable, that is controller
not found.  Even if I set environment variable as /env/vgactl, it goes to
panic.

Above observation seems to show me a problem on memory space.  My memory
setting reported by Plan 9 is as follows:

    1253 free pages, 5012K bytes, swap 29972K, highwater 248K, headroom 308K.

Well, I'm still investigating what's wrong.   However, I started to doubt
the codes of vga drivers (under the /sys/src/cmd/aux/vga) spent much time.
I got tired....  If anyone else could help me where I'd better to 
investigate, please let me know it.

Kenji