What is a Computer? How a Computer Works?

Tech Sourav

Over the last 2 decades, Computers and other computing devices have changed the way we work, communicate and learn. It is therefore important to know that:

What is a Computer & How does it work?

A computer is an electronic device that stores, Processes and retrieves data. The term Computer was first used for humans performing numerical calculations using mechanical devices such as abacus and slide rules. We now use computers for our day to day work for creating word processing documents, presentations, spreadsheets, accounting, database management, office automation, and more.

What is a Computer

Computers are used for recording, analysing, sorting, summarizing, calculating and storing data. Computers are powerful devices that can perform. Calculations of large amounts of data within microseconds, nanoseconds or even picoseconds, depending on the power of the computer. It can do millions of calculations within seconds which may take months for humans to do.

Computers can perform all activities with 100 per cent accuracy if the inputs provided are correct, otherwise, garbage in will be garbage out (GIGO). Computers can store large amounts of data in different formats such as text, graphics, audio, video, animation, simulation etc. Computers are great to help us as it can perform monotonous, repeatable work without any error and save our time. For libraries, it is a great boon as it can automate many of the library functions and cut downtime of doing it manually.

These are the major advantages of computers. But they also have some limitations.

A computer has to be instructed to do a job, as it has no intelligence and cannot take any decision on its own. This means that computers are dependent on human beings. You must be wondering what makes a computer such an incredibly perfect and powerful machine. A computer is nothing but a programmable machine that responds to instructions to store, retrieve and process data with high speed and accuracy.

It is an electronic device that manipulates information or data through programming.

A computer has four functions to perform:

  1. Input data that is data is fed in through some input device like a keyboard.
  2. Store data and instructions are saved so as to process the data
  3. Process data, and perform some arithmetic and logical functions to convert the raw data into some meaningful information.
  4. Produce output, after processing the data you get the output in the form of meaningful information as desired, it could be just a text report or a graphical representation

The main characteristics of a computer are

  • Speed
  • Accuracy
  • Automation
  • Storage
  • Endurance
  • versatility


Computers of all types and makes essentially comprise two basic parts:

  1. Hardware
  2. Software

What is a Computer


Hardware is any part of your computer that has a physical structure such as the CPU, Keyboard, Mouse, and Monitor.


Software is any set of instructions that tells the hardware what to do. Some basic Software is Microsoft paint, Microsoft Word, Google Chrome, Adobe Photoshop, etc.

Now let us see how a computer works.

  1. In the First step, data gets fed into the computer through some input device
  2. The data is then stored in some memory device for use in future.
  3. The next step is the data stored in the memory, the device is recalled through some software and processes the data as per the software instructions.
  4. Data processed then generates an output in some meaningful way as desired as information, it could be just a text file, a graphic or a multimedia component.

The output could be in softcopy form available on an output device such as the computer monitor, or it could be printed as a hard copy using a printer.

So computers have 4 major functionality:

  • Input data
  • Store data
  • Process data
  • Generate output


Different components of the computer control all these four functionalities. Now let us see the role of different computer components which carry out these 4 major functions:

Input Unit:

Contain devices which help in entering data into the computer, it is an interface between the user and the computer that translates the data in meaningful form, which is understandable by the user.

Central Processing Unit (CPU):

CPU is known as the brain of the computer which performs all kinds of data processing activities such as storing data, intermediate results and instructions and controlling the operations of all components of the computer.

CPU has 3 components

  • Arithmetic a Logical Unit (ALU)
  • Memory Unit
  • Control Unit


Output Unit:

Comprises devices which provide us output in the form of information in some meaningful format.

Now let us see how computers evolved over the years:

First Generation:

The first generation of computers was available from 1946 to 1959. The computers used vacuum tube-based technology for memory and circuit of the Central Processing Unit (CPU). The vacuum tubes produced a lot of heat and would fuse frequently. As a result, the maintenance cost was very high and only large organisations could afford to have them. The first generation computers used punch cards, paper tapes and magnetic tapes as input-output devices. The batch processing operating system was used for data processing and machine codes were used as the programming language.

Second Generation:

Second-generation computers were available from 1959 to 1965. In this generation, transistors were used for the memory and the CPU which were much cheaper compared to the vacuum tubes. These consumed less power and were compact in size. The processing was much more reliable and faster as compared to the first generation computers. Magnetic core was used as primary memory and magnetic tapes and discs were used as secondary memory devices. Assembly language and high-level programming languages like FORTRAN and COBOL were used with batch processing and multiprogramming operating systems.

Third Generation:

Third generation computers were available from 1965 to 1971. In which integrated circuits replaced the transistors. This further reduced the size of computers and was more efficient in functioning. The third generation saw the advent of remote processing, time-sharing, and multi-Programming operating systems with the use of High-level languages FORTRAN-II to IV, COBOL, PASCAL PL/1, BASIC, ALGOL-68 etc.

Fourth Generation:

Fourth-generation came into being during 1971-1980, which used Very Large Scale Integrated. In short, VLSI has about 5000 transistors and other circuit elements with their associated circuits on a single chip. This saw the advent of made microcomputers, Which were more powerful, compact, and affordable? This resulted in Personal Computer (PC) revolution.

All the high-level languages like C, C++, DBASE etc., were used with time-sharing, real-time networks, and distributed operating systems.


Fifth-generation is what we have today. It started in the 1980s when we saw a shift from VLSI technology to ULSI technology i.e. Ultra Large Scale Integration technology. As a result, we now have microprocessor chips having ten million electronic components. This generation is based on parallel processing hardware and AI (Artificial Intelligence) software which makes computers think like human beings. All the high-level languages like C and C++, Java, .Net etc., started to be used in this generation. Fifth-generation also saw the advent of different types of computers such as desktops, laptops, notebooks ultra-books etc.

Now let us talk about different types of computers that are being used nowadays.

PC (Personal Computer):

Generally, low cost and designed for an individual user for word processing, presentation, spreadsheet and database management applications. At home, it is also used for playing games or surfing the internet. Workstations the second type are used for high-end applications such as graphic designing, multimedia, desktop publishing or software development. Generally, these systems come with high-resolution displays and mass storage facilities.


These are midsize multi-processing systems capable of supporting up to 250 users simultaneously.


Very large in size and is an expensive computer capable of supporting hundreds or even thousands of users simultaneously. Mainframe executes many programs concurrently and supports much simultaneous execution of programs.


Supercomputers are very expensive and are employed for specialized applications requiring an immense amount of mathematical calculations. Supercomputers are one of the fastest computers currently available and are used for weather forecasting, scientific simulations, nuclear energy research etc.

Now coming to personal computers, personal computers can be further classified into:

Desktops, which are staying at one location. It has a display unit, a vertical or horizontal tower containing the CPU, Memory and Storage devices and input devices like keyboard and mouse attached to it. Nowadays all one desktop is available where the tower is merged with the display unit.

Laptops are portable computers more efficient, and nearly as powerful, as desktop computers. They run on AC power or batteries. No external connections are required for standard usage of the laptops. If need be you can attach other external devices.

Notebook is a term coined by Intel that describes a portable computer about half the size of a traditional laptop. Hybrid computers refer to 2-in-1 PC that comprises a screen and detachable keyboard, combining the functionality of a laptop and a tablet. These have the power of a computer and, when the keyboard is detached, the portability of a tablet. Microsoft Surface is a good example of a hybrid computer.

Tablet PC is a mobile computing device that let you do many of the same things as a traditional computer. They are best suited for applications that do not require a large amount of precise user input. So now let us summarise what we learned in this tutorial.

We covered:

  1. what is computer science?
  2. what is a computer network?
  3. generations of computers?
  4. Different types of computers?
  5. what is a PC?

Leave a Comment

Your email address will not be published. Required fields are marked *

Scroll to Top