How the computer is working? [A step-by-step guide]

We all see the different machines around us. But, among all those, computers have a unique specialty. And now on this page, we are going to see ‘How computers work?’

Computer can capable to do various things that a normal human can’t do.

In the good olden days, computers are not moveable, and they are bulky that a single computer can occupy an entire room. This happened because the technology was in a developing stage in that period.

Integrated Circuits, nanotechnology, and Artificial intelligence came to light in the 20th century. But the computer was invented in the 19th century.

So in the initial days of computers, they are bulky, less perform, and high investment machines.

But present-day computers are too smart. They know how to work in time with accuracy. In fact, human work is not even being compared with computer work.

We (humans) make computers work better and better with the help of Integrated circuit technology, the Internet, Programming languages, Artificial Intelligence, etc.

However, learning about computers is not a one-day practice. Today, we are going to see the working of a computer in a step-by-step guide.

By this, a person who knows nothing about computers can also understand its working.

Computer Working

The computer working is not a hard task to understand. Yet, it is the collection of various parts performing in a PC (Personal Computer).

We need to simplify the subject to understand well. Every component in a computer must perform a specific action. Based on this action, the computer component is being placed in one of these three sections.

  • Input
  • Central Processing Unit (CPU)
  • Output
flow of working in a computer.

These three sections will define the entire computer working.

Let’s ignore the complicated methods to understand. Here I provide the simple one to get it. Computers evolved to solve our problems, especially mathematical problems.

So, I want to take one simple example to define the entire process ” 2+3=5.”


We need to give a command or instruction to a computer with the help of input devices like a Keyboard, Mouse, microphone, scanner, etc, to take a specific action. The type of input varies from device to device. For example, a keyboard is used to give data input, a mouse is used for selection, a microphone is used for recording, etc.

Things need to be clear.

We want to get a result from the computer to our query “2+3=.” The computer needs to know our query. So, we can give our query ‘2+3=’ as data input to the computer.

The computer doesn’t mind what type of device we are using to give a command to it. The only thing is, it needs our commands.

But here the problem is not all devices are capable to do all works. For example, we can’t give the voice command ”2+3=” with a keyboard, and a data input “2+3=” with a scanner. So, we use different devices to give different types of data input.

Computer Input Unit
Computer Input Unit

Keyboard :

A keyboard is a numerical and alphabetical data input device to a computer. It is one of the compulsory parts of a computer. We can control the entire computer actions with a keyboard. But we can’t give other data input types like voice recording, scanning, etc, to the computer.

We need to type our query “2+3” in a calculator on a PC. And press ‘Enter.’ That’s all. With this action, our human command was completed.

Mouse :

A mouse doesn’t have a data input option like a keyboard. But, it is efficient for selection and perfection. Because Windows giving the virtual calculator option, we can select our query “2+3=” on the calculator.

As an input unit, our action is over with the mouse.

Microphone :

Our query is not related to a microphone, so don’t need this.

If in case, we are connected with a smart speaker on a PC, then we can use a microphone to get results for our query.

Scanner :

Our action is not related to the scanner. So we can avoid using it.

The reason behind why it is on this list is, you’ll get understand that not all input devices are useful for all works.

And these four (input devices) are just my examples. There are a lot of other input devices.

Our query will pass from a keyboard, microphone, and mouse to the CPU through a wired or wireless (Bluetooth) connection.

Note: Some input devices have only one action to make and the others have multiple. It depends. For example, a normal keyboard and a keyboard with a trackpad.


The Central Processing Unit (CPU) chief work is to collect the data or query from the input device, make the actions according to the user’s need and give solutions through output devices.

Just like a computer, the CPU also has three sections to store, read, and analyze the problem.

  • Memory Unit
  • Control Unit
  • Algorithmic and Logical Unit

The performance capacity of a computer depends on these three major factors in a CPU. The other factors also important, but the CPU parts and their working potentials are most important.

The motherboard is the collection of base networks in any system. If a circuit became a short circuit on the motherboard, the entire motherboard or system will get damage.

The motherboard has the printed paths which are connecting from one PC component to other. This means the communication between computer parts is done with the help of a motherboard.

Not only computers, from small IoT devices to major electronic components, but almost all the electronic components also have motherboards.

Memory Unit :

Everything you are seeing on a computer occupies some space. The hardware components like monitor, CPU, motherboard, speakers, etc consumes physical space. Digital processing systems like screen, display, audio signal, etc consumes RAM space.

The computer doesn’t read the normal human languages like English, Hindi, German, etc. Everything we are giving as an input to the computer is converted into a Binary system that can understand by the computer.

RAM is a volatile memory means it is used to store the data we are using now.

For example, you are reading this article means your device (mobile or PC) is connected to the internet. The search engines like Google will send the data of this article from their web servers to your device.

The data coming out from the search engines is collected by your web browsers and stores in volatile memory (RAM). This is because you are accessing this web page temporarily means around 5 to 10 minutes.

When you close this web page, automatically it will be erased from RAM memory.

In the present action of the computer, RAM memory will save our command ‘2+3’ for further processing.

Coming to Read-Only Memory, it is used to save data permanently means no need to use the internet connection to access it.

If you download an image or video online and save it in a location like a hard disk, SSD, Pendrive, etc, then the memory type is called Read-Only Memory, and the devices are called ROM devices.

Control Unit :

The saved memory will be controlled by the control unit.

The present simple arithmetic calculation is not a big task to the present generation computers. But, what the computer will do if hundreds of actions or commands are received at a time?

In such cases, the control unit will classify the requests priority-wise and make the requests in a queued manner (Just like people standing while stepping into the bus).

In the present action of the computer working, the command ‘2+3=’ stored in the memory unit will be sent to the processor or Arithmetic & Logical unit through the control unit.

Arithmetic & Logical Unit :

Here in this unit, the actual solution will find out to our query.

The arithmetic and logical unit are also called a processor. The processor can do various tasks like addition, subtraction, multiply, insertion, deletion, etc.

The command ‘2+3=’ is received by the control unit. The processor will make the operation based on the given input and find the solution with its capability.

If the processor is not capable enough to solve our problem, the inaccurate results will be displayed to our queries. Why you need a computer that is showing false results?

In the present action, the computer is capable to solve this simple arithmetic calculation that ‘2+3=’ and produce the result ‘5.’

As soon as the result generated, the A&LU will send the result to the control unit along with the query.

Working of Central processing Unit
Working of Central Processing Unit

The control unit collects the output data from the computer and sends it to the memory unit. In other words, the control unit can overwrite the data in the memory unit with the solution.

The control unit will decide the subject to expose the output result to the user. Here a monitor is a good source to show the result ‘2+3=5.’

The memory unit is a part of the motherboard and the monitor is also connected with it through cables like HDMI, VGA, etc. So the data will pass from the board to monitor through the cables and displays the result.

However, the A&LU generates the solution, so it is the most important part of the computer working.


We gave a query to the PC in the input unit. The computer read and solve that query “2+3=” in the central processing unit and the result 5 was generated. Now, in the output unit, the result will display (2+3=5) on the output device called monitor.

The output is also called an output unit in a computer. In this unit, we find all the devices which are capable to submit the output data or solution coming out from the CPU. There are various output devices in a computer like a monitor, speaker, printer, etc.

Output Unit of a Computer
Output Unit of a Computer

Monitor :

The monitor is one of the most essential components of a computer. Because it is used for finding the running process in a computer. To know more about the monitor and its types, click here.

The control unit decides to display the result on the monitor and it did.

The monitor does nothing except displaying the data. If the monitor displays “2+3=5,” the computer working is perfectly completed.

Here we took a simple mathematical calculation as an example. The computers can do complicated tasks also, based on system capability.

Speaker :

The speaker is also a type of output unit in a computer. In this work of finding a solution to our query “2+3=,” there is no need to use a speaker.

If we are using a smart speaker for query and to get the solution, then the CPU will send the audible output to the speaker which means we can listen to the output solution “2+3=5” from a speaker.

Just like different inputs from various input devices, we can get different outputs from different devices.

For example, I want to play a song by my voice. For this action, I need a microphone as an input device, a CPU for processing my command, and a speaker for output audio (song).

My command to a microphone is “play KEEP UP song by Akon,” the CPU will analyze my query or command and find a solution (song) to it, and send signals to the output device (speaker) to play it. So, I can hear the song. This entire process was happening in seconds because of the reason below.

Note: The speed of the current is equal to the speed of the light, which means ‘299 792 458 m/s.’ This is the maximum speed that we see till now. So, there is no chance of lagging in the performance of a computer. Some computers showing lag performance means they have incapable or outdated hardware.

Role of programming languages in a computer :

You may have heard about the programming languages like C, C++, JAVA, etc. But for what sake they are on a computer? Here you should know that.

A programming language is a language that can understand by the computer. You have already known that computer uses the binary system to make operations or actions according to our queries.

For example, we can take the above operation ‘2+3=5.’ We can give input to the computer to make this simple arithmetic calculation by C language. (The result would be the same).

A sample program…


int main () {

int a, b, sum;

printf(“\n Enter two numbers: “);

scanf( “%d %d” , &a , &b );

sum = a+b;

Printf(“sum : %d” , sum);




Enter two numbers: 2 3

Sum : 5

The arithmetic operation can be done using C language in a computer ‘2+3=5.’ In this process, the C language (High-level language) can be converted into the low-level language (Binary language) through the process of compiling by the compiler.

In fact, a normal calculation also needs programming. In Windows 10 OS they have built-in sources for all this. If there is any malfunction occurs in a computer, Windows will display the Blue Screen Of Death.

Just like a desktop PC, the laptop has also the same working mechanism. The difference between a desktop PC and a laptop is portability and performance. Here the working mechanism is the same, but the performance is different between laptop and desktop PC. Don’t get confused.


You’ve seen the working mechanism of a computer. This process is the same for computers of any generation. Hope you understand the thing.

What processor your PC has? Let me know with a comment.

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Author: Aswarth

Hey Guys, I'm an Electrical Engineer who is interested to learn Technical stuff in deep and want to give you the best quality information on this blog.

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