What is a CPU (Central Processing Unit)?

Computers have an enormous number of jobs that they complete even within a matter of seconds, prompting the need for a central processing unit (CPU) that helps manage and coordinate these tasks.

In this blog, you'll learn what a CPU is and how it operates as the central component of a computer to ensure it operates at maximum efficiency.

What is a CPU, and what is its purpose?

A CPU (central processing unit, or simply, processor) is the main chip in a computer that is responsible for carrying out all of its tasks.

Often referred to as the "brain," the processor tells all of the other components in a computer what to do based on the instructions it is given by the software running on that computer.

CPUs exist in lots of devices other than traditional computers like smartphones, TVs, and tablets.

Where is the CPU located?

In a computer, the CPU is generally found at the center of the system directly connected to the motherboard. It is usually under a cooling fan or heat sink, as the CPU would become damaged from overheating without a proper cooling mechanism. Socketed CPUs can be removed and replaced as needed over time.

In many modern applications, the CPU may be integrated directly onto a single integrated circuit with memory interfaces and input/output devices, becoming a system-on-a-chip (SoC). This is particularly common in edge and mobile solutions.

What are the main parts of a CPU?

There are three main parts of a CPU: the control unit (CU), the arithmetic logic unit, (ALU), and the registers. 

1. Control Unit (CU): This regulates the flow of input and output (I/O). It fetches instructions from the main memory and decodes into specific commands. 
2. Artithmetic Logic Unit (ALU): This is where all of the processing happens, including mathematical calculations and logical operations for decisions making, like comparing data. 
3. Registers: This is an extremely fast memory location. The data and instructions that are currently being processed during the fetch-execute cycle are stored there for quick access by a processor. 

How does a CPU work? 

A CPU can execute millions of instructions per second, but it can only carry out one instruction at a time. 

It first receives some type of input, typically from an input device--such as a monitor display screen, a keyboard, a mouse, or a microphone--from an application/system software program, like your web browser or operating system, or from memory. 

It is then in charge of four tasks: fetching, decoding, executing, and storing. (More on that in the next section.) 

Finally, there is an output of some kind, such as printing something to the screen. 

This process is called the fetch-execute cycle, and it happens millions of times per second. 

What are the main tasks of a CPU? 

Let's take a look at a CPU's four primary tasks: 

1. Fetching includes getting instructions from memory, so the CPU knows how to handle the input and knows the corresponding instructions for that particular input data it received. Specifically, it looks for the address of the corresponding instruction and forwards the request to the RAM (random access memory). The CPU and the RAM constantly work together in a process called "reading from memory." 
2. Decoding involves translating the instructions into a form the CPU can understand, which is machine language. 
3. Executing means carrying out the given instructions. 
4. Storing is the result of the execution back to memory for later retrieval if and when requested. This is also called writing to memory. 

Key CPU Terms 

Clock speed

Expressed in gigahertz (GHz), clock speed is a rough indication of how many calculations a processor can make each second. The higher the clock speed, the more calculations the processor can perform. 

Threads

A thread is a virtual component that helps deliver workloads to the CPU. The more threads you have, the faster workloads are delivered and the easier they are organized, leading to increased efficiency. 

Threads are vital to a computer's functionality because they determine how many tasks a computer can perform at any given time. 

The number of threads you have depends upon the number of cores in your CPU. Each core may have two threads depending on the specific processor and if hyperthreading is supported. For example, a dual core processor may have four threads and a processor with four cores may have eight threads. 

Hyperthreading

Many modern CPUs support a technology called hyperthreading. 

Hyperthreading works by making a single physical core appear as multiple physical cores, allowing the operating system (OS) take advantage of concurrent instruction processing and enhancing the computational power.

Cores 

Think of a human body: if threads are the hands, then cores are the mouth. 

Cores are separate physical devices within the main CPU chip that act as independent processors, taking data from the threads and performing computational tasks. Software applications can be written so that multiple cores can work concurrently on processing program data, generally referred to as multithreading.

How quickly a CPU can process data is affected by the number of available cores. The more cores a CPU has, the greater the computational power it has. As a result, more tasks can be run and completed simultaneously.

For example, a dual-core CPU has two cores, meaning that there are, in essence, two CPUs on the same chip and can run two instructions at the same time. An eight-core processor would be able to run 8 instructions at the same time.

Most modern server class CPUs have at least 8 cores with some configurations supporting more than 30 cores per processor. Motherboards can contain multiple processors connected together by the UPI, or Intel® Ultra Path Interconnect.

CPUs and Trenton Systems 

Without its "brain" operating at maximum efficiency, a computer's functionality is compromised, posing a risk to critical data and vital parts and components. 

Equipped with high core counts and advanced cybersecurity technologies, CPUs help computers securely process and analyze data to enhance computer power across a wide range of environments. 

At Trenton, we design our high-performance computers with next-gen Intel® CPUs to enhance throughput and ensure optimal performance in real-time. 

For example, our TAC is equipped with dual Intel Xeon D 1700 CPUs. With 2.32x faster processing speed and 5.73x faster AI inferencing, these processors accelerate concurrent workloads and control throughput to improve performance at the tactical edge.

We are also a member of the Intel Partner Alliance and a member of the Intel Early Access Program, which allows our customers to have access to the latest Intel technologies before they go on the market.

Through the increased efficiency provided by CPUs, we provide customized hardware and software solutions that provide needed insights to make critical decisions ianywhere, anytime.