Live State Machine
UML statechartA traffic-signal controller drawn as a genuine UML state machine — initial pseudostate, three states, four guarded transitions. Firing an event (or letting the timer run) moves a live token: the active state glows, the taken transition pulses, and an event-trace log records the run. The diagram is not a picture of the machine; it is the machine.
4 components · 4 connections · event-driven finite-state executor
Predict guarded state transitions and identify a liveness failure.
Builds on: 8-Bit Digital Adder
An event arrives with no enabled transition from the current state. What must a deterministic machine do?
Commit before the explanation appears. This is a prediction, not a quiz score.
- initial pseudostate
- Red / Green / Yellow states
- 4 guarded transitions
- event queue + trace log
- deterministic
- one active state
- guarded, timed transitions
Enter the machine Power-on follows the initial transition into Red.
step 1 / 4 Enter the machine
control console
The token sits on the active state. Let the guarded timers run, or fire the next event by hand — the diagram is the machine.
Auto-run uses the causal stage delay configured in the timeline above.
switchboard · fault injection
test bed · mode=full
instrumentation rack
- ▸ start → RED