wales@valeria.CS.UCLA.EDU (07/10/88)
I know that "snow" is only supposed to be a problem on CGA's, but I've
always had a certain amount of snow on my Hercules-clone monochrome
video adapter in text mode.
My system is a Taiwanese XT clone with software-switchable turbo capa-
bility, and is 100% IBM-compatible as far as I've been able to tell.
The snow occurs at both turbo (8 MHz) and regular (4.77 MHz) speeds.
I've also seen the same "monochrome snow" phenomenon on a Leading Edge
Model D.
Since I've been playing around with low-level video software lately, I
decided to try eliminating this snow by using the same kind of technique
as is customary on a CGA -- except with the *monochrome* status register
at I/O port 3BAH (instead of 3DAH for the CGA). Doing this slowed down
the output a bit (not surprisingly), but the snow was still there.
I've checked Wilton's book _Programmer's Guide to PC & PS/2 Video Sys-
tems_, but it only talks about CGA snow.
Has anyone else experienced "monochrome snow"? Has anyone managed to
devise a way of fighting it? I would like to find some workaround if
possible, for two reasons:
(1) I don't have enough money right now to upgrade my video hardware.
(2) If this is a widespread problem in clone video boards, I'd like to
make my software look nice on such systems in case I start writing
programs to sell or share.
-- Rich Wales // UCLA Computer Science Department // +1 (213) 825-5683
3531 Boelter Hall // Los Angeles, California 90024-1596 // USA
wales@CS.UCLA.EDU ...!(uunet,ucbvax,rutgers)!cs.ucla.edu!wales
"We would all become unpeople, undoing unthings untogether."