Re: [stella] end of frame??

Subject: Re: [stella] end of frame??
From: Chris Wilkson <ecwilkso@xxxxxxx>
Date: Wed, 31 Oct 2001 12:43:49 -0500 (EST)
On Wed, 31 Oct 2001, Ben Larson wrote:

> It's my understanding that not all games use exactly
> 262 scanlines.  I think that's just Atari's
> recommended number.  I think some even use upwards of
> 280 or so per frame.  Evidently these games still run
> fine on NTSC television sets.

The actual NTSC number is 262.5 lines.  So already, the Atari
number of 262 is a bit offspec.  But this obviously is fine.
PAL uses 315 lines per frame.  That's pushing it for an NTSC
receiver (not to mention the color issues!) but some might work.

> My question, then, is whether these 'non-262' games
> run at a lower screen refresh rate than 60Hz (I guess
> they'd have to), and if so, does *this* cause any
> potential TV problems?

The framerate is lower.  The horizontal scanrate is 15750Hz.
Just divide that by the number of lines to get the framerate.

If the framerate is "too far" from 60Hz, the screen will roll
vertically.  Back in the good old days, TVs had a vertical hold
knob that the user could adjust to correct for this, but I don't
think you can do it with more modern sets.  Of course, the more
modern sets may be more forgiving of bad NTSC signals.

"Old tech is better tech" -Chris

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