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From: acook@athena.mit.edu (Andrew R Cook)
Newsgroups: comp.windows.ms
Subject: Re: Flicker. . .in 1024x768x256 w/Nec 3D
Message-ID: <1991Feb13.140718.26550@athena.mit.edu>
Date: 13 Feb 91 14:07:18 GMT
References: <91042.221913MXP122@psuvm.psu.edu> <15085@uudell.dell.com> <12162@ur-cc.UUCP> <15093@uudell.dell.com>
Sender: news@athena.mit.edu (News system)
Reply-To: acook@athena.mit.edu (Andrew R Cook)
Organization: Massachusetts Institute of Technology
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In article <15093@uudell.dell.com>, jporter@twaddle.dell.com (Jeff Porter) writes:
|> In article <12162@ur-cc.UUCP>, nsus_cif@troi.cc.rochester.edu (Nick Susch) writes:
|> |> 
|> |> I assume that the first person is using a Tseng ET4000 board. I also have
|> |> this board and have this annoying flicker problem. I know that 1024x768
|> |> is interlaced, but the flicker is horible under windows. If I exit
|> |> windows and run a program in 1024 mode, I *can* tell it is interlaced,
|> |> but it is *very* slight, and the screen in very easy to read. But as soon
|> |> as I start up windows in 386 mode, something happens to the card. The
|> |> flicker becomes unbarable. I have discoverd, using the option of my NEC
|> |> 3D which saves the screen setting to each particular sync, that the 1024
|> |> mode under windows is a different sync then the "regular" 1024 mode. Does
|> |> anyone know why this happens? It's like their is two modes on the ET4000,
|> |> regular interlaced, and really slow interlaced, and windows picks the
|> |> wrong one. Any help would be appreciated.
|> |> 
|> 
|> It sounds like you've got an especially bad driver 386-mode driver for
|> your VGA card.
|> 
|> Jeff Porter

Just my $.02 :

There are two main reasons that you can percieve annoying flicker :
The first is the screen refresh rate, as the gentleman noted above.  If the
windows driver uses the 60Hz mode, you will percieve a noticable 30Hz 
flicker.  If you other program puts the card in a 70Hz (yeah!) mdoe, then
you will see considerably less flicker at 35Hz (15% faster refresh).  The other
reason for the difference in percieved flicker is what you are looking at on
the screen.  Windows stuff has a lot of horizontal and vertical lines.  When
the screen is refreshed every other line, Horizontal lines can appear to flicker
a lot, especially if they are only 1 pixel wide.  Full screen graphics, on the
other hand, like gif's, have images that are more uniform.  This makes the flicker
less percievable.

Andy Cook