I haven’t seen the actual code they’re discussing in this article, but the interesting part isn’t that this was done on a system with very little RAM. From the sound of things, it works like a finite state machine. You can represent a whole lot of possible states with 128 bytes of RAM. Like, an astrologically large number of states - 2^1024, to be exact. The ability to work within the Atari’s memory constraints isn’t what’s so interesting about this algorithm, it’s that the lookup table driving the algorithm is inscrutable.