Also called a "finite state machine," it is a computing device designed with the operational states required to solve a specific problem. The circuits are minimized, specialized and optimized for the application. For example, chips in audio, video and imaging controllers are often designed as state machines, because they can provide faster performance at lower cost than a general-purpose CPU. Automatic ticket dispensing machines are another example. There are countless special-purpose devices built as state machines. See SDL and cellular automaton.