Clock
A signal that keeps flipping between 0 and 1 on its own, used to drive flip-flops, registers and RAM.
Pins
One output on the right.
How to use it
Press ▶ Play at the bottom to start it; set the speed with Slow / Mid / Fast. You can also click it to flip it by hand. Select it and use + / − to set a divider: N means it ticks once every N base periods.
Usage example
After you press Play, the clock alternates 0, 1 on its own. It usually drives a flip-flop's CLK pin — here a T flip-flop: with T = 1, Q flips on every tick.
Common mistakes
Without Play the clock doesn't move, so the flip-flops after it seem to do nothing.