> Basically, I'm wondering how many or how few scanlines I can have per
>frame before I will have any given television "roll". I believe I remember
>hearing on this list that Activision games may have been a little bit
>larger than 262 scanlines. Was this true?
I think Activision games use more lines in the visible part of the frame.
But they do less scanlines during the VBLANK and overscan part of the
frame to make up for that. 192 visible scanlines is a very conservative
value. I heard that most NTSC TVs can display over 200 scanslines.
> If I did 261 or 263 scanlines per frame, would that be ok? I am mainly
>curious because TPS needed to be modified because of a scanline problem (I
>assume), which caused flipping on some TVs. Anyone know the limits? Or am
>I forced to stay with exactly what I know.
The problem with TPS was that it did an odd number of scanlines which would
result in no colour being displayed on PAL TVs. Due to the way Atari
implemented PAL colour encoding you would get only a greyscale picture if
you did for example 261 or 263 scanlines per frame. If you always do an
even number of scanlines per frame you would get a coloured display on
PAL too, although the colours would be different from those on NTSC
VCSs.
>Otherwise, which is worse for a TV, more than 262 scanlines, or less?
The number of scanlines that your TV can handle before starting to roll
is adjustable with the VHOLD knob. Therefore there are no absolute numbers
that would work on all TVs. If your TV is perfectly tuned for 60Hz,
there shouldn't be a difference in how many lines more or less than 262
it can handle. Since PAL TVs are tuned for 50Hz display and a perfect
262 line 60Hz display is pretty close to it's lower limits, you shouldn't
do much less than 262 lines, if you want your game to display properly
on PAL systems too.
Ciao, Eckhard Stolberg
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