A Turing machine is a minimal idealization of a computer. It consists of a line of cells known as the "tape" with an active element called the "head" that moves back and forth on the tape and changes the color of cells according to a set of rules. For various initial conditions ( axis), the plot shows the number of times the head changes direction in the first 50 steps of the evolution of the Turing machine. For this Demonstration, 4096 Turing machines in each of four classes have been randomly chosen.