Mealy machine

A Mealy machine is a finite transducer whose output depends on the transition: state and input together, $\lambda: Q \times \Sigma \to \Gamma$.

Diagrams label arcs with input / output. Output changes on the edge, so an $n$-symbol input yields $n$ outputs (no free start-state tick the way Moore has). Reaction can be immediate on the event that caused the move.

Same controller briefs can often be drawn as Moore or Mealy; the difference is when the command appears relative to the input. Pick the style that matches your timing requirements, then keep the drawing consistent.

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