Difference between “system-on-chip” and “CPU”

Question

Very confused, in some websites, they have this line:

iPhone 5s

CPU: Apple A7

other websites saying that:

iPhone 5s
System-on-chip: Apple 7
CPU: 1.3 GHz 64bit dual core

other sources saying that

iPhone 5s
System-on-chip: Apple 7
CPU: 1.3 GHz 64bit dual core Apple 7

In Wikipedia, it said:

The Apple A7 is a 64-bit system on a chip (SoC) designed by Apple Inc. It first appeared in the iPhone 5S, which was introduced on September 10, 2013. Apple states that it is up to twice as fast and has up to twice the graphics power compared to its predecessor, the Apple A6. While not the first 64-bit ARM CPU, it is the first to ship in a consumer smartphone or tablet computer.

There are 2 sentences:

The Apple A7 is a 64-bit system on a chip (SoC)

and

While not the first 64-bit ARM CPU

Wikipedia also said “The A7 features an Apple-designed 64-bit 1.3–1.4 GHz ARMv8-A dual-core CPU, called Cyclone”. So System on chip is also CPU? very confused

Answer 1

The confusion stems from the fact that a System on a Chip ALWAYS contains a CPU. Traditionally computers are built from various discrete components, among them are the following simplified examples:

• CPU (Central Processing Unit) (Handles execution of code, decisions, manages hardware)

• FPU (Floating-point Unit)- Math Coprocessor for Floating point math.

• RAM (Random Access Memory) - Used as storage for the CPU in doing calculations and processing

• GPU (Graphics Processing Unit) - Co-Processor for dealing with 2d and 3d graphics

• I/0 (Input/Ouput) - Unit for input and output devices such as keyboards and printers.

As you can see, a CPU is an important part of a system, but not the only part. When we refer to a System on a Chip, All or most of the above components are integrated into a single chip. We can talk about any particular component of this SoC, such has how much RAM it has, the capabilities of its GPU, and, of course, the CPU architecture and layout.

Because in a SoC the individual components are generally not given their own unique names, the name of the SoC will often be used to refer to the CPU component. Therefore, in Wikipedia the CPU of the Apple A7 SoC is also referred to as the A7.

Answer 2

SoC (System-on-Chip) as the name implies almost always contains a CPU, graphics chip, audio, video, radio, LTE and USB controllers; therefore they work in unison aka "it's a system on a chip".

The CPU (Central Processing Unit) as it implies is the " brain" of the system.

On smaller devices such as smartphones and tablets there is limited space. So in order to save this space and pack other components (batteries, camera, speakers, etc.) most use SoCs.

So in Apple's case the SoC can be named A7, A8 or A9. So technically the higher the number, the faster and more efficient the system runs.

Its CPU can either be 1.3 GHz dual-core, 1.4Ghz quad-core, etc.

As we move on to using more and more mobile devices (smartphones, tablets, laptops) and away from desktops more and more manufacturers are using SoCs instead of having individual components.

Answer 3

As the name says, SoC (System on a Chip) is (a significant part of) a system (i.e., a computer system, a CPU, memory controller, memory, I/O devices of several descriptions, perhaps including a graphics card) on a single chip. Some of them are built for a very specific purpose, i.e., as the heart of a cellphone, or as more general-purpose machines. Some manufacturers offer several SoCs, built around the same CPU with different peripherals, tailored for different sorts of uses.

If you look at a picture of e.g. the Raspberry Pi you'll see there is just a chip on the board, much of the space occupied by connectors for external devices.