Clock
Inputs
| Pin | Type | Description |
|---|---|---|
| No input pins | ||
This element has no inputs.
Outputs
| Pin | Type | Description |
|---|---|---|
| Q | bit | Toggles between 0 and 1 on each simulation step |
How It Works
An orchestra plays at the tempo set by the conductor's baton. The clock generator is the baton of the whole digital circuit: on every simulation step it toggles 0 ↔ 1, and all the registers of the computer live by these beats.
The key property: a full cycle takes two steps — the rising edge 0→1 and the falling edge 1→0. On the edge, every sequential element whose clock input is wired to the generator captures data at the same moment; on the fall, the combinational logic calmly computes the next values. This is what synchronization means: while the program counter turns from 0 to 1 on the edge, the accumulator commits its result in that very same instant — nobody rushes ahead and nobody lags behind.
A nuance: the Clock itself has no inputs at all — you cannot steer it with a wire. In tickMode levels the tempo is commanded by the Clock Control panel buttons: Play — continuous run, Step — one tick, Pause — a stop.
Examples (generator ticks)
| Step | Generator Q | What happens in the circuit |
|---|---|---|
| 1 | 0 → 1 (rising edge) | registers capture the values on their inputs |
| 2 | 1 → 0 (falling edge) | combinational logic computes the next values |
| 3 | 0 → 1 (rising edge) | the program counter increments, registers update |
| 4 | 1 → 0 (falling edge) | the circuit prepares for the next edge |
Two steps make one clock cycle; the circuit writes only on rising edges.
Usage
No clocked circuit works without the Clock: D flip-flops (level 11), registers (level 12), the program counter (level 14) and the whole processor (levels 16–29) all wait for the edge. One generator hands the tempo to everyone — its Q output fans out to the clock inputs of the entire circuit, and in the sandbox it is always available.
A concrete use: connect Q to the clock inputs of all sequential elements, pick a speed with the slider on the Clock Control panel — and the program comes alive. For debugging press Pause and use Step: the circuit will move one tick per press.
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Frequently Asked Questions
What is clock frequency?
How many times per second Clock switches from 0 to 1: the higher the frequency, the faster the circuit runs.
How is Clock different from Manual Clock?
Clock toggles on its own every simulation step, while Manual Clock emits a pulse only when you press the Tick button — it is the step-by-step debugging tool.
What happens if you don't connect Clock to a register?
The register never sees an edge and never stores a single value — the clocked part of the circuit stays frozen in an undefined state.