What Is a CPU and What Does It Do?

Abbreviations are the tech world’s favorite way to make interesting technology incredibly confusing. When searching for a new PC or Laptop, the specs will mention the type of CPU you can expect to find in the shiny new device. Frustratingly, they almost always can’t tell you why this is so important.

When faced with decisions between AMD vs Intel, dual or quad cores and i3, i7 or i5 vs i9, it can be difficult to tell what the difference is and why it matters. It can be difficult to know which one is best for you, but we are here to help you.

What is a CPU?

The Core Processing Unit (CPU) is often referred to as the computer’s brain. Although the CPU is only one of many processing units, it is one of the most important. It is the part of a computer that performs calculations, actions, and runs programs.

 

The CPU receives instruction inputs from the computer’s RAM, decodes and processes the action before it outputs. CPUs are found in all types of devices, from computers and laptops to smartphones, tablets and smart TVs. Small and usually square, the chip is placed on the motherboard of the device and interacts with other hardware to power your computer. 

How Do They Work?

There have been many improvements over the years since the first CPUs hit the scene. However, the basic functionality of the CPU remained the same and consisted of three steps; fetch it, decode it and run it.

Bring

As you can imagine, bringing in involves receiving an instruction. The instruction is represented as a series of numbers and transferred from RAM to the CPU. Each command is only a small part of any process, so the CPU needs to know which command comes next. The current instruction address is held by a program counter (PC). The computer and instructions are then placed on an Instruction Record (IR). The PC length is then incremented to reference the address of the next command.

Decoding

When an instruction is received and stored on the IR, the CPU transfers the instruction to a circuit called an instruction decoder. This converts the instruction into signals to be transmitted to other parts of the CPU for processing.

Execute

In the last step, the decoded instructions are sent to the relevant parts of the CPU to be completed. Results are usually written into a CPU register that can be referenced with later instructions. Think of it like the memory function in your calculator.

How Many Cores?

In the early days of computing, a CPU would only have one core. This meant the CPU was limited to only one set of tasks. This is one of the reasons why computing is often a relatively slow and time consuming but world-changing event. After pushing the single-core CPU to its limits, manufacturers started looking for new ways to improve performance. This drive for performance improvement led to the creation of multi-core processors. These days you will probably hear terms like dual, quad or even eight-core.

For example, a dual core processor is really just two separate CPUs on a single chip. By increasing the amount of cores, CPUs were able to handle multiple processes at the same time. This had the desired effect, such as improving performance and reducing processing time. Dual core soon gave way to quad-core processors with four CPUs and even eight-core processors. Add hyper-threading and your computer can perform tasks as if it had up to 16 cores.

Understanding the Features

It is useful to know about the different brands and core numbers as well as the operation of a CPU. However, there are many options out there even with the same high end features. There are other features that can help you decide between CPUs when it’s time to buy.

Mobile And Desktop

Traditionally, computers are large static electronic devices powered by a fixed source of electricity. However, the transition to mobile and the rise of the smartphone essentially meant that we carry a computer with us wherever we go. Mobile processors are optimized for efficiency and power consumption, so the device’s battery lasts as long as possible.

 

According to their own wisdom, manufacturers  began to name both mobile and desktop processors the  same but with a set of prefixes. Although this is their different products. Mobile processor prefixes include “U” for ultra low power, “HQ” for high performance graphics and “HK” for overclocking high performance graphics. Desktop prefixes include “K” for overclocking capability and “T” for optimized power.

32 Or 64 Bit

A processor does not receive a steady stream of data. Instead, it takes the data in smaller chunks known as “words.” The processor is limited by the amount of bits in a word. When 32-bit processors were first designed, they seemed like an incredibly large word size. But Moore’s Law remained true, and suddenly computers were able to handle more than 4GB of RAM – leaving the door open for a new 64-bit processor.

Thermal Power Design

Thermal Power Design is a measure of the maximum power in Watts your CPU will consume. While a lower power consumption is clearly good for your electricity bills, it could have another surprising benefit – less heat.

CPU Socket Tipi

To create a fully functional computer, the CPU must be connected to other components via the motherboard. When choosing a CPU, you need to make sure that the CPU and motherboard socket types match.

L2 / L3 Cache

L2 and L3 cache is fast, on-board memory for the CPU to use during processing. The more you have, the faster your CPU will perform.

Frequency

Frequency refers to the operating speed of the processor. Before multi-core processors, frequency was the most important performance metric among different CPUs. Despite the addition of features, it is still an important feature to consider. For example, it is possible for a very fast dual core CPU to perform better than a slower quad core CPU.

The Brains of the Operation

The CPU is really the brain of the computer. It performs all the tasks we typically associate with computing. Most of the other computer components are really there to support the operation of the CPU. Improvements to processor technology, including hyper-threading and multi-core, played an important role in the Technical Revolution.