What is Computer? | Basic Notes on Computer System

If we say that any work without a computer is impossible, then it will not be wrong. What is Computer and how to use it? It is important to know about it for all.

In simple words, a computer is an electronic device. This is probably used for every task. I hope that after studying this article thoroughly, you will get a basic knowledge of computers so that you can get help to learn more about computers in the future. So, let's "What is a computer?" Start with this topic.

What is Computer system?

What is Computer?

Science and technology has introduced a new and powerful science tool, which is called a computer. Man to solve their problem by computing and processing data introduced this tool. This computer is derived from the word "COMPUTURE", which means calculate. So, we can say a computer is a calculating device. But now a day's computers are not only known as a calculating device but also can perform several tasks like logical and graphical works. This is computer meaning.

computer system
computer system

"A computer is a man-made electronic device that gives accurate output by performing various tasks as per the given input as well as storing it."

Computer is the machine which can do a lot of jobs at a time so, it is called versatile and multi-purpose machines. It is used for creating documents, calculation, using the internet, playing games, listening to music, drawing pictures & design, films & animation production, learning lessons, preparing progress report, preparing a presentation, issuing books, launching a rocket, controlling traffic and designing an invitation, condolence, marriage card, etc.

Full form of “COMPUTER”

                                    C         : Commonly               

                                    O         : Operated      

                                    M        : Machine

                                    P          : Particularly

                                    U         : Used for

                                    T         : Trade

                                    E         : Education

                                    R         : Research

Basic Function/Operation of Computer System

1. Input

The device which accepts data from the user is called input. The input function is performed by input devices such as keyboard, mouse, microphone, scanner, etc.

Operation of Computer System
Operation of Computer System

2. Processing 

It processes the data as the given instruction. The processing unit is in between the input unit and an output unit that is why it is called CPU (Central Processing Unit).

3. Output

It produces the results of the processing which user get or receive from the monitor, speaker, printer, etc.

4. Storage

It stores the data and information for temporary and future use. It is performed by storage devices such as RAM, Hard disk, Optical disk, etc.

History of Computer

When computer development began, it cannot be verified properly.  There were many developments in computing technology related to mechanical computing devices even before the development of first-generation computers based on vacuum tubes. Such as Abacus, Slide Rule, Pascaline, etc.

But the computer we know today began with an analytical engine built by Charles Babbage, a 19th century English and mathematics professor.

Computer development is classified into different 5 generations according to the use of the technology and the time period.

First Generation of Computer (1940 to1956)

The first generation computers used Vacuum tubes for circuitry and Magnetic Drum for memory. They used to be very big in size. It consumes a lot of power.

The cards and paper tapes are used as input devices. Being too big, it also had a lot of heat problems due to which it has also malfunctioned many times.

Machine language was used in them. For example, UNIVAC and ENIAC computers.

Second Generation of Computers (1956 to 1963)

The transistors replaced the vacuum tubes of the first generation of computers. Transistor took very less space, was smaller, was faster, was cheaper and it consumes less power than vacuum tubes.

They used magnetic tapes and magnetic disks for secondary storage. Generate less heat than the first generation computers, but still, there was a problem of heat in it.

High-level programming languages ​​like COBOL and FORTRAN were used in them.

Third Generation of Computers (1964 to 1971) 

Integrated circuits were used for the first time in third-generation computers. In which many transistors were inserted into small silicon chips called semi-conductors. Due to this, the ability to do computer processing increased to a great extent and helped to reduce its size.

For the first time, monitors, keyboards, and operating systems were used to make computers of this generation more users friendly. It was launched in the market for the first time.

Fourth Generation of Computers (1971 to 1985)

It is the specialty of the Fourth generation that Microprocessor was used in it. Thousands of integrated circuits were embedded into a single silicon chip. This made it very easy to reduce the size of the machine. This era is marked by the era of microprocessor development.

The use of microprocessors increased the efficiency of the computer even more. This work was able to do a lot of calculations.

Fifth Generation of Computers (1985 to present)

The fifth-generation belongs to today's, that was started since 1975, where Artificial Intelligence has established its dominance. Now, many new technologies like Speech recognition, Parallel Processing, Quantum Calculation have been used in new technology.

Computers of this generation is growing day by day with artificial intelligence; gradually all its functions will be automated due to its ability to make decisions on its own.

Advantages of Computer

Some advantages are as follows:-

  • Cost-effective
  • Reliable
  • Accurate- That’s why they don't make any mistakes.
  • Process a large volume of data.
  • Versatile i.e. a single computer can perform a variety of jobs. Such as printing, publishing, displaying movies, playing games, etc.

Disadvantages (Limitation) of Computer

Some disadvantages are as follows:-

  • It cannot think of its own.
  • Do not learn from any experience.
  • Tasks have to be described in brief. ( It cannot describe any task)
  • Cannot detect or correct false in logic or data.

Features of computer

1. High speed

            A computer can perform operations at a very high speed. It can solve very complex problems in a short time. It works with electronic pulses at the speed of the light. Its unit is MIPS (Millions of Instruction Per-Second). Therefore the time taken to perform a task by computer is measured in function of speed.

2. Accuracy:

A computer never makes any mistakes while performing tasks. Computers can perform several tasks at a time without any mistakes. So, the computer has 100% accuracy.

3. Diligence

A computer works 24 hours, week, months without any rest or objections. A computer can do more and more work in a short time. A man gets tired after doing some works for a long time but the computer never gets tired. So, the computer is a diligent machine.

4. Versatility

A computer is a versatility machine because it can be used in various fields such as research, communication, business, space exploration, etc.

5. Storage Capacity

It has a huge amount of capacity to store all the information and raw data. It uses floppy disks, hard disk, compact disk to store data and information.

6. Automatic

Once we give the data and instruction to the computer, it works automatically. So, the computer is an automatic machine.

Applications of Computer (Scopes/Fields/Areas)

There is no area or field where the computer does not have its role. Mainly computer scope can be seen in various areas as follows: Computer in Education, Business, Medicine, Space technology, Engineering, Movie, 3D modeling, and Animation, etc.

Classification/Types of Computer

We can use different types of computer for different purposes. Today, we can get various types of computers in the market. We need different types of computers according to the nature of work. For example, the computer used for printing and publishing differs from the computer used for space technology. The computer can be classified on the following basic. 

On the basis of Work

basis of Size

On the basis of Brand

basis of Model







IBM Compatible










Organization of Computer

A computer system is a collection of various parts. To complex a computer system several parts are connected to each other. Parts of the computer can be divided into 3 sections.

  •             Input Section
  •             Processing section
  •             Output Section

Part of Computer System

The computer itself is a complex device. It is made up of CPU, RAM, hard disk, SMPS, etc. In addition, the computer mainly uses the keyboard, mouse, and screen, as well as various accessories according to the work. Such as printer, scanner, speaker, plotter, etc. The main part of the computer is also called the system unit.

System Unit

This is the most important part of the computer. It acts as the brain of a computer. It consists of the computer's microprocessor as well as other important components. All processing is done inside the system unit. It is a box (casing) that consists of the following components.

  • Central Processing Unit (CPU)
  • Mother Board
  • Switch module power supply (SMPS)
  • Primary Memory (Main Memory)
  • Input & Output ports
  • Disk drive
  • CD-ROM
  • Expansion Slots
  • CMOS Battery
  • Hard Disk (Secondary Memory)
  • Video Card
  • Cooling Fan

Central Processing Unit (CPU)

CPU is the main part or component of the computer. It’s also called the brain or heart of The Computer System. It processes the data, sends instructions and commands to the control unit and also stores the raw data and data processing results. CPU is also divided into 3 parts. They are as follows:

  • ALU (Arithmetic Logic Unit)
  • MU (Memory Unit)
  • CU (Control Unit)

There are various types of CPU. Some of them are: 8086,8088,80286,80386,80486,80586 (Pentium), Pentium-I, II, III, and IV. The well-known CPU manufacturers are Intel, Celeron, Cyril etc.


The motherboard is a rectangular piece of fiberglass; on which electronic components are mounted through very thin parallel lines of metal. It is also called a printed circuit board (PCB).

Named picture of Motherboard
Named picture of Motherboard

The motherboard itself controls all the command systems of the computer. The entire BIOS (Basic Input Output System) of the computer is also available on the motherboard.

SMPS (Switch Module Power Supply)

The power supply box located inside the system is known as SMPS. It converts the high voltage current (220v) into a low voltage (5volt-12volt).

Main Memory

Memory is used to store data. It is IC (Integrated circuit) chip built up by silicon crystal. It can be classified into two types.

  • RAM (Random Access Memory)
  • Rom (Read-Only Memory)

Input and Output Ports

This is a connective place of any input and output device like a monitor, keyboard, mouse, scanner, etc. This is available at the back portion of the system unit. The part which looks like a collection of the hole is known as male port. The port whose input device like, mouse, keyboard is known as input ports and where output device like a monitor, printer are connected is known as the output port.

Disk Drive

A device which can read 1.44MB memory space floppy disk is known as a floppy disk drive. By this drive, it is possible to carry one small memory file to another system. Comparatively, it is expansive and durable.

CD-ROM (Compact Disk Read Only Memory)

CD-ROM is a device that reads CD/DVD. It works just like a CD/DVD player. It is placed inside the system unit and it emits to take CD/DVD as input.

CMOS (Complementary Metal Oxide Semiconductor) Battery

It gives small voltages that is used to control the configuration of the system and are read and written by the system setup program.

Video Card

It is used for better graphics mostly it is necessary for the computer in which we play high-resolution game. The video card is used to display a graphic on the computer screen. XGA type of video card is that display very fine pictures on the monitor.

Expansion Slots:

The expansion slots are used to plug-in an expansion card that provides an extra option.

Hard Disk

The hard disk is an external storage device that can store a large amount of data and information. This is called secondary memory and is also said to be a permanent memory.

Cooling Fan

This is a fan whose function is as normal fan to make cool. This is placed on the microprocessor for cooling it. When we use computer for a long time processor gets heated and there is chance to damage. For that, we use a cooling fan.


The monitor is also called a display. According to technology, there are 3 types of it.

  • CRT (Cathode Ray Tube): This is a traditional monitor bigger in size and usually not available in the market right now. The CRT monitor is replaced with LCD display.
  • LCD (Liquid Crystal Display): This type of monitor is smaller and more expensive than CRT. It consumes less power.
  • LED (Light Emitting Diode): This type of monitor looks similar to 'LCD', but 'LED' technology is different from 'LCD' these days most of the users prefer this type of monitor as its quality is much better than others and consumes less power as well.

Memory Unit

A memory unit is the storage capacity of the computer. It is made of magnetic core or silicon crystal. It can be classified into 2 parts. They are.

  • Primary Memory
  • Secondary Memory

Primary Memory

A memory used by computer firstly is known as primary memory. A memory of the computer which is attached to a system board (Motherboard) is known as primary memory. The primary memory is much faster than the secondary memory but the cost of primary memory is more expensive than secondary memory. There are 2 types of primary memory.

RAM: - RAM stand for ‘Random Access Memory’. The data stored in RAM is kept till and until power is not off. Once commuter is shut down each and every content data will be erased. That is why it is also called erasable memory or temporary memory. We can read and write in RAM.  RAM can be classified into different types:

  • SRAM (Static Random Access Memory)
  • DRAM (Dynamic Random Access Memory
  • DDRAM (Digital Dynamic Random Access Memory)

ROM: - ROM stand for ‘Read Only Memory’. ROM is also called internal memory. We can't write anything into this but can read. This memory checks the internal portion of computer. Programmers write the contents of this memory during this manufacturing time and supply with hardware (Motherboard). This is permanent type. Memory ROM can be classified into 4 types. They are:

  • PROM

Secondary Memory

It is also called external memory. It is permanent memory. Secondary storage devices are the places where data is stored for future use. They can found in the form of a magnetic disk, magnetic tape, optical disk, etc. The most common secondary storage or memory devices are hard disks, a floppy disk, ZIP disk, etc.

Hard Disk (HDD)

It is the most popular secondary storage device. It can store a huge amount of data i.e. 1 terabyte (normally 80GB). It provides us both reading and writing facilities. It is a default disk and fixed disk.

The hard disk is a smooth metal plate coated on both sides with a layer of magnetic metallic oxide. It stores data information, instruction in the concentric circle called tracks each track is further divided into different sectors.

Unit and Measurement

            4 bits           =                           1 Nibble

            8 bits           =                           1 byte

            1024 bytes   =                           1 kilobyte

           1 kilobytes x 1024 =                   1 megabyte

            1024 megabytes   =                   1 gigabyte

            and 1024 gigabytes  =                1 terabyte

Hardware of Computer

The component of computer which we can see and touch is known as hardware. For example; Monitor, Mouse, keyboard etc.

It is a general term to represent physical and tangible components of the computer itself. Various hardware components that are used in modern computers can be classified according to their functional use within a computer system Different hardware perform different works. The hardware like keyboard, mouse, and scanner are used to give data to computer.

Software of Computer

Software is a set of computer program to do some specific tasks. It tells the computer hardware how to do any job. That is why we can say without software it is impossible to do any task by hardware device. Hence software is an interface between the computer and the user like cassette player becomes useless without cassette, similarly computer without software. The software is stored in a hard disks, floppy disk or magnetic tape, etc.

The software can be divided into 3 measures groups. They are:

  1. System Software
  2. Application Software  
  3. Utility Software

System Software

System software is a group of programs, languages, etc. This allows the user to communicate with hardware. This software is normally supplied by the computer manufacturers with the computer. System software can be divided into 3 types.

  1. Language Processors
  2. Operating System
  3. Device driver

Language Processors

Communication between the computer and the douser can only be possible by language processors. Software was written to bridge this communication gap is called language software or language processor. Language processors mainly consist of the following.

  • Assembler
  • Interpreter
  • Compiler

Operating System Software

There are program which control the hardware is known as operating system software. Operating system is developed on the basis of the microprocessor which is used by the computer. There are different microprocessors in different computers and therefore different the operating system is used so the operating system design for one computer may not work in others.

See Also: Operating System Fedora

Device driver

Driver software makes it possible to connect to all computer devices and peripherals to perform their intended tasks as directed by the OS.

Application Software

It is specially prepared to do certain specific tasks. They are prepared and supplied by software companies and computer manufacturers. This software is available for applications that are common to many users and organizations. For example; MS- Office, Adobe Photoshop, etc.

Utility Software

This software is similar and does common tasks like different application software. These tasks may include arranging at list in required order, joining to program, transferring data from task to another disk managing the computer’s memory, viewing the content of a file, etc. Users need not write this kind of program themselves. This software can be obtained from different program, computer manufacturers and are called utility software. A good collection of this software makes the user task easier and simple. Some of the famous utility programs are. Norton Antivirus, PC Tools, Porky, etc.

Conclusion: The Computer is actually a very vast subject, but if we want we can make it as easy and romantic subject too. If you try, nothing is difficult.

I sincerely hope that I have given you complete basic information about what is computer and what is computer science. If you have any confusion please comment. I request all of you readers to share this information in your neighborhood, relatives, and friends so that our awareness will be there and it will benefit everyone. I need your help so that I can convey more new information to you. Please subscribe to our website.

Post a Comment