Statecharts are an extension of state machines, introduced by David Harel in 1987. In the paper, Harel used a digital wristwatch as an example model. I always thought it would be great to have an interactive demo that allows to see statecharts in action. Unfortunately, that particular wristwatch (Citizen Quartz Multi-Alarm III) is now a rarity. However, there is the iconic Casio F-91W, which ...