# What is CPU and What Does it Do?

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One of the first inventions in technology was sitting on your desk. The computer, in all its forms- from your beginner’s smartphone to your 42″ tablet, is so much more than an outlet for online shopping or a place to catch up on last night’s TV shows. It’s an intriguing and at times mysterious machine that clings together chips, hard drives, and cables in a feat of engineering brilliance. Indeed, every piece of technology can be understood as a series of moving parts. So today we’re taking a closer look at one of the most important gears behind our computing: the CPU (central processing unit)—and one type in particular: the desktop CPU.

## Key Points to Remember

• CPUs are the heart of any computer system, handling all the basic operations and controls.
• A CPU is composed of two main parts: the control unit (CU) and the arithmetic logic unit (ALU).
• The CU controls the overall operation of the CPU, while the ALU performs all the calculations and comparisons.
• CPUs are extremely fast and can handle billions of operations per second.

Also read – What is Arithmetic Logic Unit (ALU)

## What is a CPU?

The CPU, or Central Processing Unit, is the heart of a computer. It is responsible for carrying out all the instructions given to a computer. In order to understand how a CPU works, it is important to first understand the basic components that make up a CPU.

The three main components of a CPU are the control unit, the arithmetic logic unit, and the memory unit. The control unit is responsible for managing all the processes that go on inside the CPU. The arithmetic logic unit is responsible for carrying out all the mathematical operations, such as addition and multiplication. Lastly, the memory unit is responsible for storing all the data that needs to be accessed by the CPU.

Now that we know the basics of how a CPU is structured, let’s take a look at how it actually carries out its work. When a computer is turned on, the control unit will fetch the first instruction from memory and send it to the arithmetic logic unit. The ALU will then carry out the operation specified by that instruction and send the result back to the control unit. The control unit will then store the result in memory and fetch the next instruction from memory. This process will continue until all the instructions have been executed and the desired results have been shown.

The Central Procession Unit (CPU) acts as the computer’s brain, processing everything from starting the operating system to running any programme. The power of a CPU is determined by its processing speed. A CPU’s speed is expressed in gigahertz. The CPU heats up quickly because it does many calculations quickly. A cooling FAN is mounted on it to lower its temperature.

Knowing that the CPU is the computer’s brain makes you curious as to what tasks it does. Let’s look at it now.

Also read – What is Computer?

## What Work Does a CPU Do?

The CPU is the most important part of a computer. It handles all the basic operations that a computer needs to perform. The four main functions of a CPU are:

1. Fetching instructions from memory: The function of a CPU is to fetch instructions from the computer’s memory. All instructions are saved in memory at a specific address, and the CPU fetches instructions from that address. In this process, the CPU takes the address number from the program counter and sets the priority of all instructions. The CPU uses a program counter to keep track of which instruction to fetch next. This means that all instructions are executed one by one according to the priority set by the processor.

2. Decoding instructions: Once the CPU has fetched an instruction, it decodes it so that it can be carried out. Assembly language instructions are sent to the CPU, which only understands binary language. In order to decode the instructions, the CPU converts them to binary form. This process is called Decoding.

3. Executing instructions: The CPU carries out the instructions it has decoded. During the execution CPU performs three activities; it does the calculation in ALU (Arithmetic and logical unit), move data from one memory location to another, and jumps to other address. After executing the process ALU has to store the result of execution as well. These result stays in cache memory until the user wants to save it in RAM or shut down the CPU. CPU keeps repeating all the three primary functions.

4. Storing results in memory: The results of the instructions are stored back in memory so that they can be accessed by other parts of the system.

## Components of CPU

The CPU is the central processing unit of your computer. It is responsible for carrying out instructions given to it by software, such as an operating system or a program. The CPU consists of multiple components, including the Arithmetic Logic Unit (ALU), the control unit, registers, and cache memory.

The ALU is responsible for carrying out arithmetic and logical operations. The control unit fetches instructions from memory and decodes them. It then sends signals to the ALU to carry out the necessary operations. Registers are temporary storage locations for data and instructions that are being used by the CPU. Cache memory is a type of high-speed memory that is used to store frequently accessed data.

Let’s know bit more about CU and ALU…

The Control Unit (CU): Control unit coordinate to transfer the data between microprocessor and ALU. It does not execute the programme instructions but serves them to ALU. The complete workflow of CPU is also controlled by CU. Control unit of CPU is run by the instructions stored in the computer’s memory; RAM and ROM.

The Arithmetic and Logical Unit: ALU does all types of computation; arithmetic or logic. The arithmetic operations include addition, subtraction, multiplication, and division. The logical calculations are based on the comparison.  These comparisons are based on AND, OR, XOR and NOT operations.

## How does a CPU Work?

Here we will understand how CPU works with the example of only one instruction but in actual CPU processes many instructions in one go.  Let’s know in detail how the CPU works in stepwise.

Step 1: some instruction is given to CPU.

Step 2: CPU draws it from the RAM (Random Access Memory) and some other hardware for the purpose.

Step 3: CPU reads the information associated with the task given to it and send it back to RAM. After reading the information from the computer’s memory the CPU starts its calculation and thereafter transporting the data.

Step 4: CPU also has to make sure that data travel through the System BUS. System Bus is a communication system through which data is transferred among all the components of the computer.

Step 5: In the system bus, the data is arranged in the correct order. And that’s how the CPU completes the assigned work. As the last step of getting the action done, CPU saves the data in the system’s memory.

To conclude the working style of CPU we can say that the instructions move from memory to control unit then Arithmetic Logic Unit then again come to memory and thus the output is ready.  You can understand the same with the below mentioned chart.

If you are curious to know more about how a CPU works, then you need to know about the primary functions of CPU. Let’s have a look at them.

## CPU in a NutShell

So far, we’ve presented a grotesquely simplified explanation of how a CPU operates. The CPU has a lot of gear to support it in carrying out any command. Typically, a CPU has one ALU; however, many Morden and modern CPUs also have many ALUs.

Data is loaded into the control section from the system RAM (memory) when a command is executed. Two numbers are read from RAM by the control section. The system bus receives the second number, whereas the ALU register receives the first. The ALU then completes all of the calculations and saves the outcome in a separate register. Data is read from there, processed further, and stored in memory by the CPU.

And that’s how the CPU functions.

## Final Words

In conclusion, the CPU is an important part of every computer system as it acts as the control center, processing and executing instructions. It is important to understand how a CPU works in order to maintain your computer system effectively. If you have any questions about CPUs or how they work, feel free to leave a comment below and we will do our best to answer them.

So far, we’ve presented a grotesquely simplified explanation of how a CPU operates. The CPU has a lot of gear to support it in carrying out any command. Typically, a CPU has one ALU; however, many Morden and modern CPUs also have many ALUs.

Data is loaded into the control section from the system RAM (memory) when a command is executed. Two numbers are read from RAM by the control section. The system bus receives the second number, whereas the ALU register receives the first. The ALU then completes all of the calculations and saves the outcome in a separate register. Data is read from there, processed further, and stored in memory by the CPU.

And that’s how the CPU functions.

## Final Words

In conclusion, the CPU is an important part of every computer system as it acts as the control center, processing and executing instructions. It is important to understand how a CPU works in order to maintain your computer system effectively. If you have any questions about CPUs or how they work, feel free to leave a comment below and we will do our best to answer them.

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