Outer totalistic five-neighbor 2D cellular automaton rules depend on the sum of their four neighbors and the value of the center site. Here, "memory" is introduced by taking the center site value from a previous time step. Memory 0 corresponds to the regular outer totalistic rule, where the center site value is taken from the current time step. With memory 1, the value of the center site is taken from the previous time step, and so on.
Select a rule number and a memory value, and observe the evolution of the system in time. In the rule table shown at the bottom, the darkness of the outer cells indicates the sum of the outer cell values, ranging from 0 (white) to 4 (black).