What is Computer?

The computer is an electronic device that takes input from the user and processes these data under the control of a set of instructions (called program) and gives the result (output) and saves future use.

Note: Charles Babbage is the father of computer.

Working process of Computer?


Input - Process - Output Concept (IPO)

The concept of generating output information from the input data is also referred to as input-process-output concept.

Input - Accepts data
Processing - Process data
Output - Produces data
Storage - Stores data

Input (Data):

Input is the raw information entered into a computer from the input devices. It is the collection of letters, numbers, images etc.

Process :

Process is the operation of data as per given instruction. It is totally internal process of the computer system.


Output is the processed data given by computer after data processing. Output is also called as Result. We can save these results in the storage devices for the future use.

Input device list :-

  • 1) Keyboard
  • 2) Mouse
  • 3) Scanner
  • 4) Joystick
  • 5) Light Pen
  • 6) Digitizer
  • 7) Microphone
  • 8) MICR (Magnetic Ink Character Recognition)
  • 9) OCR (Optical Character Recognition)
  • 10) Digital Camera


The keyboard is a basic input device that is used to enter data into a computer or any other electronic device by pressing keys. Keyboards are connected to a computer through or a bluetooth device for wireless/ USB (Universal Serial Bus) communication.

Normally there are 105 keys in keyboard. There are 12 function keys : F1 to F12, 2 control keys, 2 shift, 2 Alt keys, 2 Windows keys (in some keyboard). The first key in Keyboard is ESC.


The mouse is a hand-help input device which is used to move cursor or pointer across the screen. It is pointing device. The mouse has three buttons : Left, Right and Scroll button.


The scanner uses the pictures and pages of text as input. It scans the picture or a document.


A joystick is also a pointing input device like a mouse. The movement of stick controls the cursor or pointer on the screen.

Light Pen:-

A light pen is a computer input device that looks like a pen. The tip of the light pen contains a light-sensitive detector that enables the user to point to or select objects on the display screen. It is not compatible with LCD (Liquid Crystal Display) screens.


Digitizer is a computer input device that has a flat surface and usually comes with a stylus. It enables the user to draw images and graphics using the stylus as we draw on paper with a pencil.


The microphone is a computer input device that is used to input the sound. It receives the sound vibrations and converts them into audio signals or sends to a recording medium.

Magnetic Ink Character Recognition (MICR)

MICR computer input device is designed to read the text printed with magnetic ink. It is widely used in banks to process the cheques and other organizations where security is a major concern.

Optical Character Recognition (OCR):-

OCR computer input device is designed to convert the scanned images of handwritten, typed or printed text into digital text.

Digital camera:-

It is a digital device as it captures images and records videos digitally and then stores them on a memory card.

Output device list :-

  • 1) Monitor
  • 2) Printer
  • 3) Projector
  • 4) Speaker
  • 5) Plotter
  • 6) Headphones
  • 7) Braille Reader


The monitor is the display unit or screen of the computer. It is the main output device that displays the processed data or information as text, images, audio or video.


A printer produces hard copies of the processed data. It enables the user, to print images, text or any other information onto the paper.


A projector is an output device that enables the user to project the output onto a large surface such as a big screen or wall.


Plotters are used to print graphical output on paper. It interprets computer commands and makes line drawings on paper using multicolored automated pens. It is capable of producing graphs, drawings, charts, maps etc.


The speaker is a device that is used to hear the sound played by our computer system. The speakers can be connected to a laptop, computers, mobile phones, and tablets with the help and assistance of a USB or audio jack. The speakers are connected with an audio card installed on the motherboard or built-in sound card.


Headphones is a output device that can be plugged into a computer, laptop, smartphone, mp3 player or other device to privately listen to audio without disturbing.

Brallie Reader:-

A Braille Reader also called a Braille display, it is an electronic device that allows a blind person to read the text display on a computer monitor.

Central Processing Unit (CPU)

Central Processing Unit (CPU) consists of the following features :−

  • CPU is considered as the brain of the computer.
  • CPU performs all types of data processing operations.
  • It stores data, intermediate results, and instructions (program).
  • It controls the operation of all parts of the computer.

CPU itself has following three components.

  • Memory or Storage Unit
  • Control Unit
  • ALU(Arithmetic Logic Unit)


Control Unit:

This unit controls the operations of all parts of the computer but does not carry out any actual data processing operations. It communicates with Input/Output devices for transfer of data or results from storage.

ALU (Arithmetic Logic Unit)

This unit consists of two subsections namely:

Arithmetic Section

Logic Section

Arithmetic Section:

Function of arithmetic section is to perform arithmetic operations like addition, subtraction, multiplication, and division. All complex operations are done by making repetitive use of the above operations.

Logic Section

Function of logic section is to perform logic operations such as comparing, selecting, matching, and merging of data.

Memory Unit:

Memory Unit is the part where the computer stores and retrives the data.

There are two types of types of memory:

1. Primary Memory (RAM)

2. Secondary Memory (Hard Disk)


Primary or Main Memory :

Primary memory is also known as the computer system's main memory that communicates directly within the CPU. Main memory is used to kept programs or data when the processor is active to use them. When a program or data is activated to execute, the processor first loads instructions or programs from secondary memory into main memory, and then the processor starts execution.

The primary memory is further divided into two parts:

RAM (Random Access Memory)

ROM (Read Only Memory)

RAM (Random Access Memory):

Random Access Memory (RAM) is one of the faster types of main memory accessed directly by the CPU. It is volatile, which means if a power failure occurs or the computer is turned off, the information stored in RAM will be lost.

There are two types of RAM:
1. SRAM   2. DRAM

SRAM: SRAM (Static Random-Access Memory) is a type of RAM used to store static data in the memory. It means to store data in SRAM remains active as long as the computer system has a power supply. However, data is lost in SRAM when power failures have occurred.

DRAM: DRAM (Dynamic Random-Access Memory) is a type of RAM that is used for the dynamic storage of data in RAM. If the power is switched off, the data store in memory is lost.

Read-Only Memory (ROM) :

ROM is a memory device or storage medium that is used to permanently store information inside a chip. It is a read-only memory that can only read stored information, data or programs, but we cannot write or modify anything. A ROM contains some important instructions or program data that are required to start or boot a computer. It is a non-volatile memory; it means that the stored information cannot be lost even when the power is turned off or the system is shut down.

There are mainly three types of ROM:
1. PROM   2. EPROM   3. EEPROM

1.PROM (programmable read-only memory):

PROM is a computer memory chip that can be programmed once after it is created. Once the PROM is programmed, the information written is permanent and cannot be erased or deleted.

2. EPROM (Erasable and Programmable Read Only Memory):

It is the type of read only memory the data which stored can be erased and re-programmed only once in the EPROM memory. an EPROM can be reprogrammed if needed, first we need to pass the ultraviolet light for 40 minutes to erase the data; after that, the data is re-created in EPROM.

3. EEPROM (Electrically Erasable and Programmable Read Only Memory):

Electrically Erasable and Programmable Read Only Memory can be erased and reprogrammed using an high voltage electrical charge. In EEPROM, the stored data can be erased and reprogrammed up to 10 thousand times. EEPROM was a replacement for PROM and EPROM chips and is used for later computer's BIOS (Basic Input/Output System)that were built after 1994.

Secondary Memory:

Secondary memory is a permanent storage space to hold a large amount of data. Secondary memory cannot be accessed directly by the CPU, it means the data in the secondary memory is first loaded into the RAM then which can operate easily by the CPU. All the stored data such as audio, video, pictures, text, software, etc in a secondary memory cannot be lost because it is a permanent storage area; even the power is turned off.

Ex: - Solid-state drives (SSDs), Hard disk drives (HDDs), Cloud storage, CD-ROM drives, DVD drives, Pendrives, SD cards etc

Cache Memory:

It is a small-sized chip-based computer memory that lies between the CPU and the main memory. It is a smaller and faster memory that stores copies of the data from frequently used main memory, it means the Cache Memory holds frequently requested data and instructions so that they are immediately available to the CPU when needed.


Register Memory:

It is the smallest and fastest memory of a computer. It is a part of computer memory located in the CPU as the form of registers. The register memory is 16, 32 and 64 bits in size. These are the memory locations that are directly accessible by the processor.


Computer Memory Unit in Measurement:

Computer memory is the storage space in the computer, where data is to be processed and instructions required for processing are stored.

Bit: The computer memory units start from bit. A bit is the smallest memory unit to measure data stored in main memory and storage devices. A bit can have only one binary value out of 0 and 1.

Byte: It is the fundamental unit to measure data. It contains 8 bits or is equal to 8 bits.


Generations of the computer

First-generation (1940 - 1956):

The first electronic computer used vacuum tubes as a serious piece of technology that was ENIAC, which stands for Electronic Numerical Integrator and Computer, invented by J.W.Mauchy and J.P.Eckert.

Second generation (1956 - 1963) :

Instead of vacuum tubes, the second generation of computers was supported transistors. From 1956 through 1963, transistors were widely utilized within the second generation of computers.

Third generation (1964 - 1971):

The third generation of computers was supported Integrated circuits. In 1958-1959, Jack Kilby and Robert Noyce invented the IC (Integrated circuit), which was a signal component that could have a number of transistors.

Fourth generation (1972 - 2010):

The Microprocessor, commonly called a CPU (Central Processing Unit), was used by the fourth generation of computers. A microprocessor is used in a computer that led to makes a computer more powerful and small in size as well as fits easily on a desk

Fifth-generation (2010 to present):

Fifth-generation computers may use neural networks and artificial intelligence and try to make decisions that mimic human beings. They can interpret information and make decisions. The ten million electronic components have consisted of the production of a microprocessor as this generation is based on Ultra Large-Scale Integration (ULSI). The Full form of VLSI is Very-large-scale integration.


Software is a set of programs (sequence of instructions) that allows the users to perform a well-defined function or some specified task.

The software is made up of binary language (composed of ones and zeros). Software programmers write the software program in various human-readable languages such as Java, Python, C#, etc.

Main types of software are:

1. System Software

2. Application Software

System Software:

These software programs are designed to run a computer's application programs and hardware. It controls the operations of the computer hardware and provides an environment or platform for all the other types of software to work in. The OS is the best example of system software; it manages all the other computer programs.

They are the first thing that gets loaded in the system's memory wherever you turn on your computer. System software is also known as "low-level software" because the end-users do not operate them.

In System Software, include the basic I/O (Input/Output) system procedures, the boot program, assembler, computer device driver, etc.

The further classifications of system software are as follows:

1. Operating system:

The operating system is the most prominent example of system software that acts as an interface between the user and system hardware. It is a group of software that handles the execution of programs and offers general services for the application that runs over the computer.

Examples of Operating Systems are given below:

Microsoft Windows, Apple's iOS, Apple's MacOS, Android, CentOS, Linux, Ubuntu, Unix

2. Device Drivers:

In computing, the device driver is a type of software that operates or controls some specific hardware devices linked to your system.

Examples of Device Drivers are given below:

BIOS (Basic Input/Output System) Device Driver, USB (Universal Serial Bus) Drivers, Motherboard Drivers, Display Drivers, Printer Drivers, Sound Card Driver, ROM (Read-only memory) Drivers, VGA (Video Graphic Array) Drivers

3. Firmware:

In electronic systems and computing, firmware is a type of permanent software embedded in the system's ROM (read-only memory) to provide low-level control for some particular system device hardware. It is a set of instructions that are stored permanently on your computer's hardware device.

Examples of Firmware are given below:

Computer Peripherals, Consumer Appliances, Embedded Systems, UEFI (United Extensible Firmware Interface), BIOS (Basic Input/Output System)

4. Utility Software :

These software analyzes and maintain a computer. These software are focused on how OS works on that basis it perform task to enable smooth functioning of computer.

It perform specific tasks to improve the performance, security, and functionality of a computer system.

These software may come along with OS like windows defender, windows disk cleanup tool. Antivirus, backup software, file manager, disk compression tool all are utility software.

Examples of Utility Software are given below:

Antivirus, File Management Tool, Disk Management Tool, Commpression Tool (Win Zip, 7-Zip, Win Rar), Disk Cleanup Tool, Disk Defragmenter

How to compress any Files:

Step I : Download 7-Zip software from Internet.

1. Goto Google Chrome.

2. Type Download 7-Zip for Windows.

3. Find Official Link of related software.

4. Choose your file to download according to OS bit (32 or 64 bit ).

5. Click Download button.

Step II. Install 7-Zip software in your computer.

1. Goto download folder and search your 7-Zip software.

2. Right Click on 7-Zip software.

3. Click on "Run as administrator".

4. Click on "Yes" on User Account Control.

5. Click on "Install" button.

6. Finally Click on close button.

Step III. To Compress any folder.

1. Right Click on the folder which you want to compress.

2. Click on 7-Zip.

3. Choose and click on "Add to Filename.7z" or "Add to "Foldername.zip".

4. Your compressed file is ready.

How to decompress(extract) your compressed file.

1. Right click on compressed file.

2. Click on 7-Zip.

3. Choose and Click "Extract Files" or "Extract Here".

Your decompress file is ready.

Application Software:

Application programs or software applications are end-user computer programs developed primarily to provide specific functionality to the user.

An application can be self-contained, or it can be a group of programs that run the application for the user. Examples of modern applications include office suites, graphics software, databases and database management programs, web browsers, word processors, software development tools, image editors and communication platforms.

Difference between Open-source Software and Proprietary Software:

1. Open-source software is computer software whose source code is available openly on the internet and programmers can modify it to add new features and capabilities without any cost. Proprietary software is computer software where the source codes are publicly not available only the company which has created can modify it.
2. Here the software is developed and tested through open collaboration. Here the software is developed and tested by the individual or organization by which it is owned not by the public.
3. In open-source software the source code is public. In proprietary software, the source code is protected.
4. Open-source software can be installed on any computer. Proprietary software can not be installed into any computer without a valid license.
5. Users do not need to have any authenticated license to use this software. Users need to have a valid and authenticated license to use this software.
6. Users can get open software free of charge. Users must have to pay to get the proprietary software.

Mobile Apps

A mobile application, most commonly referred to as an app, is a type of application software designed to run on a mobile device, such as a smartphone or tablet computer.

List of Government Mobile Apps:
1) Aarogya Setu App
2) Aaykar Setu App
4) DigiLocker App
5) ePathshala App
6) GST Rate Finder App
7) Indian Police at Your Call App
8) mAadhaar App
9) MADAD App
10) mParivahan App
11) mPassport Seva App
12) MyGov App
13) PMO India App
14) UMANG App

1) UMANG APP : Unified Mobile Application for New-Age Governance (UMANG) has been developed as a single mobile platform to deliver major Government services. Hon’ble Prime Minister has dedicated UMANG to nation on 23rd November, 2017. UMANG App is available on Android, iOS, Windows & Web. It can be downloaded by giving missed call on 97183-97183. This app is offered by the Ministry of Electronics and Information Technology (MeitY) along with the National e-Governance Division (NeGD).

2) DigiLocker APP : As name suggests, this you can it store your digital documents. The Ministry of electronic & Information Technology (MEITY) offers this app as part of the digital Indian initiative DigiLocker is directed towards minimizing the dependence on physical document. It was launched to the public by Prime Minister Narendra Modi on 1 July 2015.

3) BHIM APP :BHIM (Bharat Interface for Money) is an Indian mobile payment app developed by the National Payments Corporation of India (NPCI), based on the Unified Payments Interface (UPI). Launched on 30 December 2016, it is intended to facilitate e-payments directly through banks and encourage cashless transactions. It was named after Dr Bhimrao Ambedkar.

IT Gadgets And Their Application

Gadgets : A Gadgets is a small tool or device that has a specific useful purpose.

1. Smart watch : Smart watches are just like your smartphones internet access enable smartwatch with whole world of potential capabilities like message notifications GPS navigations and calendar synchronisation and of course a bluetooth connection to your phone means the what can help you play calls or send and receive messages.

2. Google Glass : Google Glass is a wearable, voice- and motion-controlled Android device that resembles a pair of eyeglasses and displays information directly in the user's field of vision.

3. PDAs (personal digital assistant) : Personal digital assistant PDA is a hand held computer that fits in the palm of your hand to help collect search information as contact appointments file and programs.

4. Drone camera : Drone camera is a device installed in a drone that is meant to record videos or to capture photos while the drone is flying.

5. Pen with camera : A spy pen camera is an example of electronic miniaturization because it contains tiny versions of larger equipment, such as a still photo camera or an audio/video recording system.

6. Bluetooth Speakers :Bluetooth speakers are a type of wireless speakers that are aimed at improving convenience and comfort of listening to music or watching videos.