Introduction to Computer

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A computer is an electronic machine that accepts data from the user, processes the data by performing calculations and operations on it and generates the desired output as a result. The term computer is derived from the Latin word ‘computare’ which means ‘to compute’.

Generally, computer is the combination of Hardware and Software which converts data into information. Computer operates on set of instructions only, they cannot think as human being. Computer has an ability to store and execute set of instructions called program which makes it extremely distinguishable and versatile than calculators. Computer makes people’s lives easier and more comfortable.

 Functioning of a Computer

Computer Performs four basic functions -which are as follows

  1. Input Information or data that is entered into a computer is called input. It sends data and instructions to the Central Processing Unit (CPU).
  2. Processing It is the sequence of actions taken on data to convert it into information which is meaningful to the user. It can be calculations, comparisons or decisions taken by the computer.
  3. Output It makes processed data available to the user. It is mainly used to display the desired result to the user as per input instructions.
  4. Storage It stores data and programs permanently. It is used to store information during the time of program execution and possible to get any type of information from it.

Features of Computer

The key features of computer are as follows

  1. Speed The computer can process data very fast at the rate of millions of instructions per second.
  2. Accuracy Computers provide a high degree of accuracy. They respond to the user as per the input instructions.
  3. Storage Capacity Computers are capable to store huge amount of data which depends on the capacity of hard disk.
  4. Versatility Computers can do different types of work simultaneously. They can perform multiple tasks at a same time.
  5. Automatic Once the instruction to do any work is given to the computer, the computer does its work automatically by itself.
  6. Diligency Unlike human beings, a computer is free from monotony, tiredness, lack of concentration, etc and can work for hours without creating any errors.
  7. Secrecy Leakage of information is reduced by creating login system with password protection.
  8. Reliability Computer are more reliable than human beings. Computers always produce exact results. The possibility of errors occur only if the input is wrong, i.e. the computers never make mistakes of their own accord.
  9. Plug and Play Computers have the ability to automatically configure a new hardware and software component.

 Terms Related to Computer 

  1. Hardware It is the collection of physical elements that constitute a computer system. It is a comprehensive term for all the physical parts of a computer, e.g. display screens, disks, keyboards, etc.
  2. Software It is a set of programs and procedures. Software tells the hardware what to do and how to accomplish a task. e.g. Web browsers, Word processors, etc.
  3. Data Unprocessed raw facts and figures, like numbers, text on pieces of paper, are known as data.
  4. Information When data is processed, organised, structured or presented in a given context so as to be useful, then it is called information.
  5. Instruction It is a command given to a computer in the computer language by the user.
  6. Program It is a set of instructions given to a computer in order to performs some task.

History of Computer

Computer is not the creation of one day, rather it took a long period for the development of modern computer. History of computer is described in this table

Abacus 1602China·      First mechanical, calculating device. ·      A horizontal rod represents the one, tens, hundred, etc.·      Used for addition and subtraction operations. Calculation of square roots can also be performed.
Napier’s Bones 1617 John Napier·      Three dimensional structure. ·      Holding numbers from 0 to 9 only. ·      Represent graphical structure of calculating result.·      Perform multiplication on numbers. ·      Technology used for calculation called Rabdologia.
Pascaline , 1642 Blaise Pascal·      First mechanical adding machine. ·      It was structured like rectangular box, with eight disc (represent number of units).·      Perform addition and  subtraction of two numbers. Mainly designed with regard to the pressure of liquid.
Jacquard’s Loom 1801 Joseph Marie Jacquard·      Mainly weaved a silk based pattern. Used punched card for the sequence of operation.·      Simplified the process of Textiles.
Analytical Engine 1837Charles Babbage  (Father of computer)·      First general-purpose computer. ·      Stored program in the form of ‘pegs’ also called barrels.·      It was a decimal machine used sign and magnitude for representation of a number.
Tabulating Machine 1880 Herman Hollerith·      It used punched cards with round holes. It was the first electromechanical machine, designed to process the data for census in 1890.·      Read one card at a time.
MARK-1 1944Howard Aiken·      Consists of interlocking panels of small glass, counters, switches and control circuits. ·      Data can be entered manually.·      Mainly used in the war effort during World War-II ·      Magnetic drums are used for storage.
ENIAC 1946JP Eckert and JW Mauchly·      It is a combination of twenty accumulators. ·      First electronic digital computer.·      Used for weather prediction, atomic energy calculation and other scientific uses.
EDSAC 1949John Von Morris Wilcus·      It was first computer which provided storage capacity. ·      First computer program was run on machine.·      Capable of storing instructions and data in memory. ·      Used mercury delay lines for memory, vacuum tubes for logic.
UNIVAC 1951Eckert  John Mauchly·      First general-purpose electronic computer with large amount of input and output.·      Used magnetic tapes as input and output.
IBM-650 Computer 1954 IBM Company·      Provided input/output units converting alphabetical and special characters to two-digit decimal code.·      Payroll processing ·      Oil refinery design ·      Market research analysis

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Generations of computer

A generation refers to the state of improvement in the development of system. Computers are built of electromechanically, before generation.  Each generation of computer is characterised by a major echnological development that fundamentally changed the way, computers operate.

GenerationSwitching DeviceStorage DeviceSpeedOperating systemLanguageCharacteristicsApplications
First (1940-56)  Vacuum tubesMagnetic drums333 micro second  Batch operating systemMachine language(Binary number 0’s and 1’s) Fastest computing device Generate large amount of heat. Non-portable.Used for scientific purpose e.g. ENIAC, UNIVAC, MARK-1, etc.
Second(1956-63)Transistors (Made up of semiconductor)  Magnetic core technology10 micro secondsTime sharing system, Multitasking OS Assembly language, high level languageMore reliable and less prone to hardware failure. Portable and generate less amount of heat.Used for commercial production e.g. PDP-8, IBM-1401, etc.
 Third (1964-71) Integrated Circuits(ICs) (Made up of silicon) Magnetic core as primary storage medium 100 Nano secondsReal-time systemHigh level language(FORTRAN, COBOL, ALGOL)Consumed less power. Highly sophisticated technology required.Database management system e.g. NCR-395. B6500,etc.
 Fourth (1971- Present) Large Scale Integrated (LSI) circuit microprocessor Semi-conductor memory Winchester disk 300 Nano seconds Time sharing, GUI interface. PASCAL, ADA, COBOL-74 FORTRAN IVMore reliable and portable. This generation leads to better communication and resource sharingDistributed system, e.g. Intel 4004 chip, Macintosh.
 Fifth(Present and Beyond) Super Large Scale Integrated (SLSI) chips Optical disk – –Knowledge Information Processing system –Parallel processing. Intel core microprocessor is implemented. Enables mega chips. Artificial intelligence e.g. Robotics
  • Siddhartha was the first computer developed in India.
  • Alan Turing is known as the father of the modern computer.
  • John Von Neumann was introduced first architecture of computer in the year 1948.

Classification of Computer

Computers are mainly classified as three types as follows

Based on Size

On the basis of size, computers are categorised as follows


Microcomputers are the least powerful, yet the most widely used and fastest growing type of computers and are also called portable computers. Microcomputer consists of three basic categories of physical equipment, i.e. system unit, input/output unit and memory unit.

Some types of microcomputer are as follows

(a) Desktop Computer or Personal Computer (PCs) These are small, relatively inexpensive computers. These are based on the microprocessor technology (Integrated Circuit, 1C). In 1958, Jack Kilby and Robert Noyce invented the first 1C.

(b) Laptop These computers are also known as ultra-book or notebook. These are portable, lightweight and fit into most briefcases. They include rechargeable battery, so these can work anywhere.

(c) Handheld Computer These are the smallest and are designed to fit into the palm. So, these are also known as Palmtop. They are practical for certain functions such as phone books and calendars. They use the pen for input instead of keyboard.

(d) Tablet Computer They have key features of the notebook computer, but these can accept input from a pen instead of the keyboard or mouse.

(e) Personal Digital Assistant (PDA) It is also known as a handheld PC, or personal data assistant, is a mobile device that functions as a personal information manager.


Minicomputers are smaller in size, faster, costlower than mainframe computers. Initially, the minicomputer was designed to carry out some specific tasks, like engineering and Computer Aided Design (CAD) calculations. But now, they are being used as central computer which is known as Server. Minicomputers are IBM-17, DEC PDP-11, HP-9000, etc.

Mainframe Computer

Mainframe computers are those having large internal memory storage and comprehensive range of software. Mainframe computer serves as a backbone for the entire business world. It is considered as the heart of a network of computers or terminals that allows a large number of people to work at the same time. Mainframe computers are IBM-370, IBM-S/390, UNIVAC-1110, etc.


Supercomputers are the fastest and most expensive machines. They have high processing speed compared to other computers. The speed of supercomputers are measured in FLOPS (Floating Point Operations Per Second). Supercomputers are used for highly calculation intensive tasks, such as weather forecasting, nuclear research, military agencies and scientific research laboratories. Supercomputers are most powerful, large in size and memory, compared to all other computers.

  • CRAY-1 was the world’s first supercomputer introduced by Seymour R CRAY in 1976.
  • PARAM was the first supercomputer developed in India in 1990.
  • PARAM Kanchenjunga is the latest machine in the series of PARAM made by NIT (National Institute of Technology) Sikkim 17th April 2016.
  • Tianhe-2 is the world’s fastest supercomputer launched by China at NUDT university in 2013. It is based on Rylin Linux operating system with 33.86 petaflops.

Based on Work

On the basis of’ work, computers are categorised as follow

Analog Computer

Analog computers are the job-oriented computers. They carry out arithmetic and logical operations by manipulating and processing of data. e.g. speedometers, seismograph, etc. Analog computer can perform several mathematical operations simultaneously. It uses continuous variables for mathematical operations and utilizes mechanical or electrical energy.

Digital Computer

Digital computers work by calculating the binary digits. A digital computer, not only performs mathematical calculations, but also combines the bytes to produce desired graphics, sounds. e.g. desktop (PC),

Hybrid Computer

Hybrid computers are the combination of analog and digital computers. Machines used in hospitals like ECG and DIALYSIS are the commonly used hybrid computers.

Based on Purpose

On the basis of purpose, computers are categorised as follow

General Purpose Computer

General purpose computers are those computers, which are used to solve variety of problems by changing the program or instructions, e.g. to make small database, calculations, accounting, etc.

Special Purpose Computer

Special purpose computers are those computers which are used to solve a single and dedicated type of problem, e.g. automatic aircraft landing, multimedia computer, etc.

Quantum computer was first introduced by Richard Feynman. It uses quantum mechanical phenomena It is the fastest computer imitating brain working.

Applications of Computer

Now-a-days computers have been employed in almost all the aspects of professional and personal life. Some of the areas Where computers are being used are as follows

  1. Education Computers have proved to be excellent teachers. Educational institutes are using computers in many ways like tele-education, virtual classroom, online classes, etc.
  2. Science and Engineering Scientists have been long users of it. A new adventure among scientists is the idea of a collaboratory, an Internet based collaborative laboratory, in which researchers all over the world can work easily together even at a distance.
  3. Industry Computers are used here to control manufacturing system and continuous running of the machinery. Parameters like temperature, pressure, volume are monitored and controlled by computers. Robotics developed with the help of computers, plays a very crucial role here.
  4. Recreation Our entertainment and pleasure time have also been affected by computerisation.
  5. Administration Various departments of the government use computer for their planning, control and law enforcement activities.
  6. Health Computer plays a very crucial role in this area. Activities like scanning, X-ray, tele-medicine, patient monitoring, patient records, diagnosis, etc., are performed with the help of computers.
  7. Multimedia It is the field concerned with the computer controlled integration of text, graphics, drawings, animation, audio and any other media where each type of information can be represented, stored, transmitted and processed digitally.
  8. Banks Computers can be used in the banks to keep the records of customer’s accounts.
  9. Military Personnel They also make use of computers for their crucial tasks like determining the weather, computing the trajectories of missiles, etc.
  10. Business Using a wide range of business software a company’s marketing division can produce sales forecasts and devise new strategies.
  11. Commerce It is the activity of buying and selling of goods and services especially on a large scale.
  12. Publication Computers have made publication process an easy one. Without computers, the different parts of a publication-text, illustrations and graphics-must be created individually, then cut out and pasted down to form a page layout.