See the instructions below the displayed trace
Copyright © 2002 Horace Townsend
Press 'Start' and an irregular quasi-sinusoidal trace appears. It is, in fact, two identical superimposed traces. After a while press 'Disturb'. [This adds 0.01 to the value of y ] For 2 to 3 seconds there is no change, then the disturbed trace becomes slightly different, finally the two traces, while generally similar are quite independent. You can stop the display at any time by clicking 'Stop' and restart it by clicking 'Start'. While the trace is running Pressing 'Disturb will have no obvious effect. Pressing 'Again' will cause the disturbed trace to revert to a copy of the first one.
Have fun!