Alan Turing's "Turing machines" provide for a universal notion of computation. Wolfram|Alpha simulates, analyzes and gives information about the rule space of many Turing machines. It also creates interactive visualizations, including network visualizations, of the evolution of Turing machines. Specify a rule number or explicit rule or just give a number of states and colors for a random sample.
Investigate this simple model of a computer with simulations, analysis and visualizations.