Re: [stella] Built-in screen saver

Subject: Re: [stella] Built-in screen saver
From: emooney@xxxxxxxxxxxxxxxx (Erik Mooney)
Date: Fri, 06 Aug 1999 14:05:52 GMT
>" An example of extensive color manipulation is a subroutine developed by
>Mr. Decuir to avoid burning game patterns onto the TV screen if the VCS is
>left unattended. The routine, which cycled through all possible
>color-luminance combinations, used only a dozen bytes, a great advantage in
>early game cartridges, which held only 2 kilobytes of ROM. "In 2K, you
>barely have room to brush your teeth," Mr. Decuir said."
>
>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?  

To clarify, it's not a built-in routine (there's no ROM in the console),
it's just a standard routine included in a number of games.  In most
Atari-produced games (usually not for other companies), all the color
accesses went through a lookup table, to accommodate the color/BW switch,
and it probably made PAL conversion easier.  It wouldn't be that hard to
initialize a counter at powerup or game over, increment it every frame,
and change the index into the lookup table every so many frames.

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