²¹In order to calculate the number of possible states of the PONG state machine, one assumes the game is played on a 160x192 pixel screen of the Atari VCS 2600 game unit (popular in 1976). We have two x-variable elements with the paddle graphics and one xy-variable element in the ball graphics which are all free to assume any position on the screen. Thus the number of possible game states can be calculated as 160*192*160*160 (neglecting the position limitations due to the size of the game elements) which ends up to be approximately 3 Billion game states.