Re: [stella] 60fps vs 30fps

Subject: Re: [stella] 60fps vs 30fps
From: Aaron Bergstrom <Aaron.Bergstrom@xxxxxxxxxxxxxx>
Date: Sat, 21 Dec 2002 06:37:32 -0600
Oops, sorry... force of habit... Ok... I think I get it now. So what bizarre thing would happen then if I ran through my vsync, my vblank, my 192 scanlines, my overscan.... and then wasted a whole frame's worth of machine cycles before going back to the vsync at the top of my draw routine?

Andrew Davie wrote:

Hmm... so if I were to create a 30mhz game I would simply not return to
the beginning of the draw loop at the end of the overscan, but instead
use an entire frame's worth of machine cylces performing game
calculations before I return to the beginning of the draw loop?

No. Please see my earlier follow-up post.

The Atari 2600 requires you to generate appropriate data for a TV frame,
which basically consists of 262 lines at 60Hz (frames/second).  You can't
get away from this.  If your game is to run at 30Hz, then you do the game
LOGIC (as opposed to the TV frame generation) once every two TV frames.  But
you still need to generate the actual frame data at 60Hz for the TV.

So your draw loop must keep running at 60mph.  Let's keep the abbreviations
correct, it's the only way we can avoid misunderstandings :)


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