What is a system on a chip?

A system on a chip puts the CPU, graphics and most other parts of a computer onto one chip, like a small city.

1. Many chips become one
Older computers used a separate chip for each job. A system on a chip (SoC) puts most of them on one chip, as phones and most laptops do.
2. Each part is a block
Each part of an SoC is called a block, and each block has one job. The blocks sit side by side, like buildings in a city.
3. Roads between the blocks
A network on the chip, called the fabric, carries data between blocks like the city's roads. Memory chips sit beside the SoC, and the memory controller talks to them.
4. Each block has its own switch
Each block has its own power switch and clock; engineers call these power and clock domains. One block can slow down or switch off while others keep working.
5. One design, many products
Makers switch some cores off and set different speeds and power limits, so one design becomes many products.

Words to know

SoC (system on a chip): One chip that holds most parts of a computer.
Block: One part of an SoC with one job, such as graphics.
GPU (graphics processing unit): The block that draws pictures. The display block then sends them to the screen, so the screen can stay on while the GPU is off.
NPU (neural processing unit): The block built for AI math.
Memory controller: The block that moves data to and from the memory chips.
Fabric: The on-chip network that carries data between the blocks.
Domain: A group of circuits that slow down or switch off together. Domains can share one power supply, each with its own on-chip switch.

Testers note which blocks each power feature touches. Switching off an idle GPU touches one block; sleep touches the whole chip.

Why can the GPU switch off while the CPU keeps working?Think first, then tap to see the answer.

Each block has its own power switch and clock.