How The Computer is Working? [Step-by-Step]

We all see 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?’

A computer can be capable of doing various things that a normal human can’t do. And this is the reason we can use computers in many professions like research, editing, content creation, etc. Here you can find how the computer is useful in multiple ways.

In the good olden days, computers were not movable, and they were so bulky that a single computer could occupy an entire room. This happened because the technology was in a developing stage at 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 were bulky, less performing, and high-investment machines.

But present-day computers are too smart. They know how to work in time with accuracy. 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.

With the information on this page, a person who knows nothing about computers can understand what’s happening inside the computer briefly.

Computer Working

Computer working is not a hard task to understand. Yet, it is the collection of various parts and their functioning.

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

  • Input
  • Central Processing Unit (CPU)
  • Output
Computer working block diagram

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 give a specific command. 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.

The input devices of a computer and their use

We want to get a result from the computer for 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 can do all the work. 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.


A keyboard is a numerical and alphabetical data input device for a computer. It is one of the compulsory parts of a computer. We can control the entire computer’s 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” into a calculator on a PC. And press ‘Enter.’ That’s all. With this action, our human command was completed.


A mouse doesn’t have a data input option like a keyboard. But, it is efficient for selection and perfection. Because Windows gives 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.


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

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


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

The reason behind why it is on this list is, that you’ll 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 others have multiple. It depends. For example, a normal keyboard and a keyboard with a trackpad.


The Central Processing Unit’s (CPU) chief work is to collect the data or query from the input device, make 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 are also important, but the CPU parts and their working potentials are the most important.

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

The motherboard has printed paths that are connected from one PC component to another. 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 devices also have motherboards.

Memory Unit :

Everything you are seeing on a computer occupies some space. The hardware components like the monitor, CPU, motherboard, speakers, etc consume physical space. Digital processing systems like screens, displays, audio signals, etc consume RAM space.

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

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

For example, if you are reading this article that 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 stored in volatile memory (RAM). This is because accessing this web page temporarily means around 5 to 10 minutes.

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

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

Coming Read-Only Memory is used to save data permanently means no need to use an 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 for the present generation of computers. But, what will the computer 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 units are also called a processor. The processor can do various tasks like addition, subtraction, multiplication, 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, inaccurate results will be displayed in our queries. Why do you need a computer that is showing false results?

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

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

The control unit collects the output data from the computer and sends it to the memory unit. 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 to it through cables like HDMI, VGA, etc. So the data will pass from the board to monitor through the cables and display the result.

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


We have a query to the PC with the input unit. The computer can 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 the monitor.

The output is also called an output unit in a computer. In this unit, we find all the devices which can 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.


The monitor is one of the most essential components of a computer. Because it is used for finding the running process in a computer.

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

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

Here we took a simple mathematical calculation as an example. Computers can do complicated tasks based on system capability.


The speaker is also a type of an 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 a 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 with 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 the 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 be understood by a computer. You have already known that computers use binary systems 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 the 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.

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

Just like a desktop PC, the laptop also has the same working mechanism. The difference between a desktop PC and a laptop is its 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 do you have on your PC? Let me know with a comment.