GoKawiilDeveloper builds interactive Casio F-91W demo using XState statecharts
A developer created an online, interactive model of the Casio F-91W digital watch that implements its logic using the XState statecharts library, building on an earlier digital recreation by Alexis Philip. The project pairs the watch interface with the Stately visualizer so users can see states and transitions as they interact with the watch, referencing David Harel's 1987 statecharts paper which originally used a digital wristwatch as its example.
GoKawiil's interpretation of the reporting above, not reported fact.
The demo offers a tangible, hands-on way to understand statecharts, an abstract computer science concept, by tying it to a widely recognized consumer object still sold today. It also provides a modern substitute for Harel's original example watch, the Citizen Quartz Multi-Alarm III, which is now difficult to find, potentially making the concept more accessible to students and developers.
- The project reimplements the Casio F-91W's logic using the XState statecharts library instead of the original scripted logic.
- It uses the Stately visualizer to show states and transitions alongside the watch interface for educational purposes.
- Some real watch behaviors are simplified or omitted, including day-of-week setting, held-button incrementing, and actual alarm triggering.
Source: github.com, 2026-10-12
Published there as: “Casio F-91W using Statecharts”
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