By controlling the timing and sequence of switches, the drum performs repetitive switching operations.

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A programmer may change or rearrange (reprogram) peg or cam positions.

Much like the pegs in a music box cylinder activate the notes, in a drum sequencer, as the drum of the sequencer spins, the pegs run across switches activating machine processes.

Cam timers don't have the greater degree of flexibility that CPU-based controllers provide.

As well as offering more wash program variations, a CPU based washing machine controller can respond to malfunctions, automatically initiate test cycles, reducing manufacturing costs, and provide fault codes in the field, again reducing repair costs, and providing feedback on real world failure rates and causes.

These are common in washing machines, where the cam timer runs in phases, but also stops and waits for external signals such as a fill level sensor, or a water heating temperature sensor.

While still fairly popular, cam timers are mechanical and hence subject to wear and reliability problems.Some cam timers also have a fast forward mode, where applying power to a point on the controller causes rapid advance of the mechanism. Rapid advance can be achieved by moving of gearing, which may be triggered by various means.Using feedback and external time delay and other sensory circuits, it is possible to build an electromechanical state machine using a cam timer.Usually washing machines thermostats have fewer fixed temperature detection points than the number of wash temperatures used.For intermediate temperatures, the cam mechanism uses the stop and wait method to heat to the nearest temp below the one desired, then uses only fixed timing of the heating element to increase the water to the desired temperature.Occasionally more complex timers with two motors are seen.