12 Nov
2006
12 Nov
'06
4:53 p.m.
On Sat, 11 Nov 2006, jim stephens wrote:
Teo Zenios wrote:
Many of the better quality cards of that era did exactly that. I ran such
a setup up until about 4-5 years ago when I swapped out my 486 for a P166,
which I'm currently still using.
I have a 386/40 and a 486 EISA system that
sometimes boot in mono mode
instead of color. Any idea why that would be? The CMOS seems to keep
its settings and the time is correct.
Ted,
I think that the video bios initialization had some early forms of
monitor sensing. I believe that there was a monochrome mode vga monitor
supported, which looked better with a modified grey level fed to it
rather than just feeding it a color signal and trying to clean it up in
the monitor. If it is the 9 pin video that was used by some XGA and
PGA that does not
apply, but only to the VGA.
I saw it do this, and found that plugging in the right monitor and
getting it to decide to run in mono mode caused it to stay that way
regardless of what monitor i subsequently attached, so it is definitely
the card and system doing it.
If you are running linux, or could load a "live" linux and boot it, I
would think that the utilities under linux, or under dos that queries
the adapter bios as to the modes it will drive would be different
depending on what mode it comes up in as well.
I can't remember for sure now, but I believe I was able to switch the
video mode under Linux when the system was already running when I'd swap
over to the color monitor. I used the gray scale VGA while coding for
hours on end as I found it to be easier on my eyes than a color VGA
monitor that was almost exactly the same. The two monitors were NEC 2A and
gs2A. I still have them, but they both began to suffer from old age, both
in bad caps and I believe the tube in the 2A was starting to degrade.
I was able to purge out a video card and monitor card
to get rid of my
problem, but I realize EISA cards are probably a bit rare.
They all use about the same approach to the vga bios though.
My guess for intermittent troubles would be a loose connector. I had to
replace the DE-15 on my 2A monitor's cable for that very reason.
I'd so like to find one or more reasonably priced 17" mono VGA monitors
these days...
-Toth