The Blinker: Simplest Oscillator
Three cells cycle between horizontal and vertical, forever.
Tick 0 · horizontal
500 ms / tick
The middle cell always has exactly two neighbors and survives. The end cells die of loneliness. The cells above and below gain exactly three neighbors and spring to life. One tick later, the logic reverses.
living cells
dies of loneliness next tick
springs to life next tick
digit = living neighbors