Re: [stella] Built-in screen saver

Subject: Re: [stella] Built-in screen saver
From: Eckhard Stolberg <Eckhard_Stolberg@xxxxxxxxxxxxxxxxxxxxx>
Date: Fri, 06 Aug 1999 14:14:15 +0200
At 00:06 06.08.99 -0500, you wrote:

>Is this just a subroutine that is accessed in the "mainloop" (to use Nick
>Bensema's playfield code)?  Does anyone know what this code looks like, and
>how it checks if a game is idle or not, and how long the game waits before
>a screen saver mode hits?  

I haven't seen the actual code, but I think it works something like this:
The early Atari games checked the COLOUR-B/W switch once per frame, so
that they could set the colours apropriately. I think that they probably
did some bit manipulation with the colour values before they were written
to the TIA colour registers, if the game wasn't in play mode. I also think
that they used one byte to tell if the game is in play mode. One bit
toggles the mode and the other seven bits work as a counter for the next
change to the colour modifier. This would result in a colour change about
every two seconds, which seems to be what the games do.


Ciao, Eckhard Stolberg



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