You can't really call this an animation as it's really more of a program. I wrote the original in C++ under DOS a few years back and in the space of around eight hours today, found out enough about Flash 8's ActionScript to port it to Flash.

On startup, the script generates a 256 colour pallete, sometimes known as a 332 pallete. The name comes from the fact that red and green get 3 bits and blue gets 2 in the indexing scheme. For a pallete that only contains 256 out of 16777216 colours, the 332 pallete does a pretty good job at displaying 24-bit images at 8-bit screen resoultions.

The main part of the script uses a very simple formula to get the results:

y = x ^ t;

(^ is the bitwise exclusive-OR operator in many programming languages, C++ and ActionScript among them)

The value of t is incremented every iteration and different initial values for t produce slightly different results (a value of zero is used here). My original C++ program prompted you for the initial value of t at startup, but I can't figure out how to do that with Flash just yet (for all I know, it might not even be possible).

The original program ran at 320*200. This version runs internally at 256*144 and then blows up the pixels. While it is technically possible to run it at a higher resolution, the results don't look as good (mainly because everything ends up so small). Also, while it is possible to use a pallete with more entries, it takes too long to go through them and spoils the results. 256 entries are enough for this.