Rocket taps a pencil on the bench, fast. "If I were a processor, how many taps a second?" he asks. He manages about five.
Raven listens to the laptop on the bench. "What do you notice?" she asks. "It is silent, but it is doing something."
Nova pulses her lights like a tiny drum. "Every processor has a clock," she says. "Not for telling time. For keeping steps in time. Would you like a hint? Think about a metronome."
Inside every processor is a clock. It does not show hours and minutes. It makes a steady tick, over and over.
With each tick, the processor moves to its next step. The ticks keep every part of the processor in time. They are like a drum beat for a marching band.
The speed of the clock is counted in ticks per second. One tick per second is one hertz.
Modern processors tick billions of times each second. One gigahertz means one billion ticks every second.
| Thing | About how often |
|---|---|
| Your heart | About one or two beats a second |
| Rocket tapping a pencil | About five taps a second |
| A hummingbird wing | Dozens of beats a second |
| A processor clock | Billions of ticks a second |
A billion is a huge number. If you counted one number every second, a billion would take over thirty years.
Even at billions of ticks a second, a processor can run out of time.
A game might need a huge number of steps for every picture it draws. If the steps take too long, the picture arrives late. The game stutters.
Closing other apps gives the game more of the processor's time. A simpler game needs fewer steps and runs smoothly on an older device.
This is why the crew asks: what is the processor busy doing?
| Statement | True or false? |
|---|---|
| A processor clock shows the time of day. | ? |
| One hertz is one tick per second. | ? |
| A processor ticks only a few times a second. | ? |
| Closing extra apps gives a game more processor time. | ? |
You found the heartbeat of the machine! Tomorrow you will learn the only two things a processor can tell apart. On and off.