What Is a CPU (Central Processing Unit)?

In order to keep things running smoothly on a computer, there needs to be a central hub where information gathers for processing. This central hub is known as the central processing unit (CPU). A CPU is the core component of any computing device you own. In this article, learn what a CPU is, how central processing units work, and why they're so important.

What is CPU?

CPU stands for the central processing unit. It's an electronic circuitry that performs arithmetical, logical, controlling, and input/output operations given by a computer program running on that computer. Alternatively referred to as a processor, central processor, or microprocessor, the CPU is the main piece of hardware that defines a computer. It's essentially the brain of the computer system, carrying out most of the computer's crucial tasks.

The instruction cycle helps the central processing unit perform its primary job of coordinating and executing various tasks. It fetches the instructions from the computer's memory, decodes them, and then executes the necessary operations. The main ones include arithmetic calculations, logical comparisons, and data movement. Because a CPU tells all the other components in a computer what to do, it must interpret commands from the computer's other hardware and software.

While the CPU is a core component, it can only function alongside other hardware. It sits in a specific socket on the motherboard designed to receive it. Although it works closely with RAM, the central processing unit is separate from the memory, which is where information is temporarily stored.

Central processing units are not exclusive to traditional computers, however. They exist in phones, computers, thermostats, and other technology and Internet of Things devices. As technology has advanced, developers have created smaller and more efficient CPUs, thus allowing them integrate into other electronic devices that can run programs.

In modern computers and smartphones, it's common for the CPU to be integrated into the same physical chip as other components. This integration can include graphics processing units (GPUs), memory controllers, and other specialized processors.

Where is CPU located?

The location of the CPU varies depending on the device. In a desktop PC, the central processing unit is positioned at the core of the system. It's physically connected to the motherboard.

In some PCs, however, the microprocessor isn't directly visible when you remove the side panel because a cooling fan or heat sink covers it. This cooling apparatus is necessary because central processing units generate heat during operation. Coolers dissipate the heat generated by the CPUs in order to ensure that they operate within safe temperature ranges.

Most laptops house the CPU on the motherboard beneath the keyboard. Upgrading to a newer CPU then requires you to fit a new motherboard, as both components must be compatible.

In smartphones, the microprocessor is integrated into a single chip. This is often part of the System-on-a-Chip (SoC) located on the phone's main circuit board.

What does CPU look like?

The CPU performs millions of calculations per second to execute any program. It looks like a tiny silicon chip and contains millions of microscopic transistors and other electrical components.

These transistors function as electronic switches and act as the basic building block of circuits, so they control the flow of electricity through the chip.

In addition to transistors, the chip contains abstract layers like logic circuits and gates. The circuits perform simple logical operations, while gates do essential functions like switching on and off. All of these components work together to power modern computers.

How does CPU work?

A CPU reads, interprets, and then executes program instructions. It uses a unique set of rules and protocols known as instruction set architecture. The instructions define how a computer's central processing unit reads the binary code of a software program.

It execute a repetitive cycle known as the Fetch-Decode-Execute cycle. It retrieves data from memory, decodes it to understand the instructions, and, finally, executes the instructions accordingly.

This cycle runs continuously as long as the computer has power, with the central processing unit fetching, decoding, and executing instructions as they come in. Modern CPUs are extremely fast and efficient by design, with multiple cores that allow for parallel processing. This means that they can handle multiple tasks simultaneously.

Processing units also come with cache memory, which is a small, high-speed memory that stores frequently accessed data.

Components of CPU

The central processing unit is comprised of three major components. They are the Arithmetic Logic Unit (ALU), the Control Unit (CU), and the Registers. All three work together to ensure that the CPU performs its functions seamlessly, with each component performing a unique task.

Arithmetic Logic Unit (ALU)

The ALU performs arithmetic and logical operations based on instructions given to the CPU by software programmers. It uses registers to hold data temporarily as the central processing unit works through its tasks before storing data in memory.

Control Unit (CU)

The CU controls the entire CPU and manages the flow of instructions. It:

• reads the instructions stored in memory
• performs actions that software programmers ascribe
• directs the flow of data to its necessary location

The CU uses registers to store instructions and data addresses. Doing so helps keep track of the current state of the central processing unit.

Registers

Registers are small, high-speed memory locations used to store data temporarily for quick access by the ALU and CU. They store data during processing to allow faster communication between different central processing unit areas. They include:

• General-Purpose Registers, used to store data during processing
• Special-Purpose Registers, used to perform unique functions like power management
• Control Registers, used to contain data related to the CPU state and operation

Functions of CPU in a computer system

The CPU handles various tasks in a computer system. Thanks to the silicon chip, it can even fulfill several of these tasks simultaneously, switching between different processes. Consider the various functions of the central processing unit below.

• Fetch stored commands. The CPU retrieves stored commands from the computer's RAM. The processor locates the next instruction's address, accesses the corresponding memory location, and brings the instruction into its own internal storage for processing.
• Decodes instructions. It also interprets the fetched instructions, breaking down the instructions into constituent parts. It translates the instructions into a form that the central processing unit can understand.
• Executes commands. After decoding the instruction, the processor then executes the specified operation. Things like arithmetic calculations, data manipulation, or control flow changes take place here. The CPU ensures that the computer performs the intended tasks by carrying out the instructions sequentially.
• Stores data. The CPU has a small memory called cache, which stores data during the current sessions to improve task speed.
• Serves as a control system. CPUs also act as central hubs for devices, communicating with all other peripherals. Without this central control center, the various components in a single device would fail to function as a cohesive unit.

Types of CPUs

There are many different types of central processing units.

• Single-core CPUs were the standard for many years. However, they are now outdated, as they can only process one instruction at a time.
• Dual-core CPUs replaced single-core CPUs and can process two instructions at a time, which improved performance. The CPUs have two cores.
• Quad-core CPUs are currently the most common type of microprocessor. They can run up to four tasks simultaneously and also offer improved speeds.
• Octa-core CPUs have eight processor cores, meaning that they can offer exceptional performance for demanding applications, like gaming. However, these are more expensive and not as widely available.

What is CPU clock speed?

As a computer user, you may have heard of CPU clock speed. The clock speed of the processor is the number of cycles that a central processing unit can perform in a second, measured in gigahertz (GHz).

CPU clock speed determines how quickly a CPU performs processing tasks. Higher clock speeds indicate that the CPU can perform more tasks within a shorter amount of time.

For example, a central processing unit with a clock speed of 2.5 GHz can perform 2.5 billion cycles per second, while a CPU with a clock speed of 3.0 GHz can perform 3 billion cycles per second. This subtle difference makes a considerable impact on the performance of a CPU.

What are some advanced CPU features?

Three advanced CPU features are CPU cores, CPU threads, and advanced instruction sets.

CPU cores

CPU cores refer to the number of individual processing units within a central processing unit that can perform tasks simultaneously. The number of cores in a CPU impacts its performance significantly.

A central processing unit with more cores can handle more tasks at once. Understanding the clock speed and number of cores allows you to make an informed decision on the type of CPU that best suits your computing needs.

CPU threads

Central processing unit threads are virtual units of work that a CPU can execute. The aim is to help make a processor's performance more efficient. Hyper-threading technology, for example, is a technology Intel deploys to enable a single physical CPU core to execute multiple threads concurrently.

Within each central processing unit core, there can be multiple threads. Having a high thread count is important when your computer is dealing with heavy workloads. However, know that threads don't physically increase the number of cores in a central processing unit.

Advanced instruction sets

Advanced instruction sets are sets of instructions that go beyond the basic instructions that a central processing unit can perform. They are primarily designed to accelerate the capabilities of the processor. Modern CPUs feature advanced instruction sets for these tasks, such as multimedia processing, encryption, vector operations, and other complex computations.

Frequently asked questions

What are CPUs made of?

CPU is made up of silicon, a semiconductor material. The intense electrical activity within a CPU can cause it to heat up. Therefore, to dissipate the heat and prevent overheating, central processing units often come equipped with an integrated heat spreader (IHS).

What causes high CPU usage?

High CPU usage can come from various factors, including resource-intensive applications, multiple concurrent processes, background tasks, outdated drivers, and malware.

What's the difference between CPU and GPU?

A central processing unit focuses on general-purpose task, while a GPU specializes in parallel processing for rendering graphics and accelerating computational tasks related to graphics and image processing.

What is a CPU cache?

A central processing unit cache is a hardware cache used by the central processing unit to help cut back on the time it takes to access data from the computer's memory. Like other caches, this cache stores data that users frequently need or access. The central processing unit is split into three levels: the L1, L2, and L3 caches.