SSC General Science & Technology Computer Components Notes - Computer and Electronics

Notes - Computer and Electronics

Category : SSC


Computer & Electronic




·         The earliest known tool for computation was the Abacus. It was developed in China.

·         Blaise Pascal invented the second real mechanical calculator called Pascaline.

·         Charles Babbage is considered as the 'father of computer' because he invented difference engine in 1822 and then analytical engine, which can store the information on punch cards, in 1837.

·         Alan Turing is regarded as father of 'modem computer' science.


Characteristics of Computer

The characteristics of a computer are as follows:

·         Speed: The computer uses the electronic pulses, the speed of those pulses is virtually instantaneous and process the inputs in microseconds, nanoseconds or piccosenconds.


·         Storage: It is also known as memory. It consists of computer components and recording media used to retain digital data.


·         Accuracy: Computers are error free and most of the errors are due to human negligence.


·         Versatility: Computers are multi-tasking in nature.


·         Automation: It is a field where the computer itself executes all tasks automatically when inputs are provided to it.


Limitations of a Computer

·         No Self Intelligence: Though a computer is programmed to work efficiently, fast and accurately, yet it is programmed by human beings to do so.


·         Decision Making: The concept of artificial intelligence shows that the computer is the decision maker. But it is still dependent on instructions provided by human being.


·         Self Care: Computer cannot take care of itself like a human being. It is dependent on human beings for this purpose.


·         Retrieval of Memory: Computers can retrieve data very fast but this technique is linear. Human mind does not follow this rule.


·         Sensation: Computers cannot feel like a human being.


Generations of Computer

First Generation (Vacuum Tube) 1940-56

·         Technology: Use of vacuum tubes in electronic circuit

·         Internal Operating Speed (IOS): Milliseconds

·         Operating Systems (OS): Batch processing

·         Languages: Machine code and electric boards

·         Examples: UNIVAC-I, IBM-701


Second Generation (Transistor) 1957-63

·         Technology: Use of transistor and diodes

·         IOS: Microseconds

·         OS: Batch processing

·         Languages: Assembly language, high level language

·         Examples: UNIVAC-1004, IBM-1401


Third Generation (Integrated Circuits) 1964-71

·         Technology: Use of integrated circuits

·         IOS: Nano seconds

·         OS: Time sharing

·         Languages: High level languages (FORTRAN, COBOL, BASIC)

·         Examples: UNIVAC-1100, IBM-360, PDP-8


Fourth Generation (Microprocessors) 1971-89

·         Technology: Use of large integrated circuit

·         IOS: Picoseconds

·         OS: DOS, Windows

·         Languages: High level language (Java, C++, Python etc.)

·         Examples: ALTAIL-8800, IBM-370, PDP-8, etc.


Fifth Generation (Artificial Intelligence) 1989

·         It is the realm of programming where devices are able to think and react to the environment around them, the fields of gaming, robotics, voice recognition and real life simulation, centre on perfecting the science of artificial intelligence.


·         In this period, computing technology has achieved greater superiority and parallel processing, which was until limited to vector processing and pipelining. Thus, hundreds of processors could do all work on various parts of a single programme. Quantum computation, nanotechnology and supercomputing are going to enhance the fifth generation computing.



Based on Size

·         Nano Computer: It is a computer whose physical dimensions are microscopic.

·         Micro Computer: It is a complete computer and is generally a synonym for Personal Computer or PC.

·         Laptop: A Laptop has most of the components as of a desktop computer, including a display, keyboard, pointing device such as touch pad and a pointing stick and speakers into a single unit.

·         Net Book: It is a small, lightweight and inexpensive laptop computer suited for general computing and accessing web based application.

·         Palmtop/PDA (Personal Digital Assistant): These are very small computers that have been designed to allow people to keep necessary information at hand.

·         I Pad: It is a line of table computers/portable media players designed and marked by Apple Corporation.

·         Simputer: It is a low cost portable alternative to PCs, by which the benefits of IT can reach the common man.

·         Tablet Computer: It is a mobile computer larger than a mobile phone of personal digital assistant, integrated into a flat touch screen and operated by touching the screen rather than using a physical keyboard.

·         Mini Computer: These computers are smaller in size, faster and cost lower than mainframes computer.

·         Mainframe Computer: They are powerful computers used primarily by corporate and governmental organisations for critical applications, bulk data processing such as census, industry and consumer statistics, enterprise resource planning and transaction processing.

·         Super Computer: The super computers remain at the top of the heap in power and expense. They are used for the tasks that require massive calculations, like engineering design and testing, weather forecasting, economic forecasting, serial decryption, etc. Examples of super computers are as follows:


(i) SAGA-220: It stands for supercomputer for aerospace with GPU Architecture-220 Teraflops. It is a super computer built by Indian Space and Research Organisation (ISRO).


(ii) Titan: It is the first super computer, which is based on GPU (Graphic Processing Unit) system and the working power of this super computer is up to seventeen petaflops, i.e., floating point operations per second.


(iii) PARAM Anant: It is a low-cost super computing solution based on C-DAC's unique open frame architecture.


(iv) Blue Gene Computer: It is a super computer project at IBM for a series of high-performance System-On-a-Chip (SOC) architectures with minimal power demands. It runs on linux and employs thousands of processors, each of which demands minimal electric power.


Top-10 Super Computers of the World

S. No.

Computer Name

Country, Year


Sunway Taihu Light

National Supercomputing Center in Wuxi China, 2016[16]



National Supercomputing Center in Guangzhou, China, 2013


Piz Daint

Swiss National Supercomputing Centre, Switzerland, 2016



Japan Agency for Marine-Earth Science and Technology, Japan, 2017



Oak Ridge National Laboratory, United States, 2012



Lawrence Livermore National Laboratory, United States, 2013



Los Alamos National Laboratory, United States, 2015



National Energy Research Scientific Computing Center, United States, 2016



Kashiwa, Joint Center for Advanced High Performance Computing, Japan, 2016


K computer

Riken, Advanced Institute for Computational Science (AlCS), Japan, 2011


Based on Work

·         Digital Computer: It operates on data, including symbols, letters and magnitudes that are expressed in binary form by using only the two digits, i.e., 0 and 1.


·         Digital Computer: An analog computer is a form of computer that uses continuously variable mechanical, hydraulic or electrical quantities to simulate the problem being solved, rather than symbolic numerical values of digital computers.


·         Hybrid Computer: It is a digital computer that accepts analog signals and converts and processes them as digital signals.


Other Kinds of Computers

Other kinds of computer are as follows:

·         Optical of Photonic Computer: It is a device that uses the photons in visible light or infrared (IR) beams, rather than electric current, to perform digital computations.

·         Atomic Computer: It describes a unitary action or object that is essentially indivisible, unchangeable whole, and irreducible.

·         Virtual Computer: It allows different OS to run in the same computer at the same time without interfering each other.

·         Chemical Computer: It is an unconventional computer based on semi-solid chemical soup where data is represented by varying concentrations of chemicals.

·         DNA Computer: It uses DNA, biochemistry and molecular biology hardware instead of traditional silicon based computer technologies.

·         Neuro Computer: It also known as Wetware computer/Organic computer/Artificial Organic Brain. It is built from living neurons.

·         Quantum Computer: It uses the quantum mechanical phenomenon such as superposition and entanglement to perform operations on data.

·         Embedded Computer System: It is designed for specific control functions within a larger system. It is embedded as a part of a complete device often including hardware and mechanical parts.



·         It is the collection of physical elements, which comprises a computer. On the basis of the work, hardware can be divided into following parts:

·         Input device             -           Output device

·         Memory                   -           Processing unit


Input Device

·         In computing, an input device is any peripheral (piece of computer hardware equipment) used to provide data and control signals to a computer,

·         Keyboard: A keyboard is human interface device which is represented as a layout of buttons.

·         Mouse: It is the most commonly used input pointing device.


Membrane Computing

·         It is an area within computer science that seeks to discover new computational models from the study of biological cells, particularly the cellular membranes.

·         Magnetic Ink Character Recognition (MICR): It is used to read the characters which are written in the magnetised ink.

·         Optical Mark Recognition (OMR): It is used to read the special preprinted forms designed with boxes marked by a dark pencil or pen.

·         Optical Character Recognition (OCR): It is an optical scanner used to read an image, convert it into a set of 0s and 1s and store then in computer's memory.

·         Bar Code Reader: In this method, the optical reader recognises the small bars of varying thickness and spacing printed on packages, badges, tag and converted into electrical pulses.

·         Speech Input Unit: It is an input unit to take the input in the form of spoken words and convert them to a form which can be understood by a computer.

·         Touch Screen: The touch screen makes selection by just touching the screen.

·         Trackball: Instead of moving the whole mouse around, the user rolls the trackball only, which is on the top or side. It is mainly used in laptops.

·         Joystick: It gives a more natural feeling of control for motion in games, especially when we are flying a plane or spaceship.


Output Device

·         In computing, an output device is any piece of computer hardware equipment used to communicate the results of data processing carried out by a computer to the outside world.

§  Visual Display Unit (VDU): It is also called monitor. It displays what computer is doing.

§  Printers: It is a peripheral which produces a text or graphics of documents or pictures stored in electronic form, usually on physical print media such as paper or transparencies.

§  Plotters: It is a kind of printer that interprets commands from a computer to make line drawings on paper. Plotters are used in engineering applications, e.g. drawing maps and technical drawings.

§  Graphic Display Device: It is the video terminal capable of displaying graphs and pictorial data.

§  Speech Output Unit: It is the one which reads the strings of characters stored in the computer's memory and converts them into spoken sentences.



·         It stores all the data and the programmes. It receives, holds and delivers data according to the instruction from the control unit. It is of two types:


Primary Memory

·         It is the computer's memory which is accessible directly by the processing unit. It is basically of two types which are as follows:

(i) Read Only Memory (ROM): It is the non-volatile and resident memory of the computer. The information and instructions needed to operate a computer is present in it. Types of ROM are as follows:

§  Programmable ROM (PROM): It is a form of digital memory, where the setting of each bit is locked by a fuse or anti-fuse. It is a Programmable ROM but not alterable.


§  Erasable Programmable ROM (EPROM): It is non-volatile memory. It can be erased by exposing it to strong ultraviolet light source.


§  Electrically Erasable Programmable ROM (EEPROM): The electric pulse is used to erase the ROM instead of ultraviolet (UV) light.

(ii) Random Access Memory (RAM): It is a temporary and volatile memory. Its contents are lost when power is switched off. It is also called as temporary memory.


Types of RAM

·         Static RAM (SRAM): A bit of data is stored using the state of a flip-flop. It has no need to refresh the memory.


·         Dynamic RAM (DRAM): It stores a bit of data using a transistor and capacitor pair which together comprise a memory cell. It must be periodically refreshed to access data.


Cache Memory

·         It is a RAM that a computer can access more quickly than it can access by regular RAM. This memory is typically integrated directly with the CPU chip.


Secondary Memory

·         It differs from primary memory in the sense that it is not directly accessible by the CPU. Secondary memory is non-volatile and it does not lose the data when the power is switched off.


Types of Secondary Memory

Types of secondary memory are as follows:

·         Magnetic Storage It refers to any type of data storage using a magnetised medium. Two types of magnetic polarities are used to read the binary information representing either zero or one.

Types of magnetic storage are as follows:

§  Hard Disk Drive (HDD): It is a data storage device used for storing and retrieving digital information using rapidly rotating discs (plotters) coated with magnetic material. Generally, the capacity of HDD is 512 GB to many TB.

§  Micro SD (Storage Disk) Card: It is a non-volatile card format for portable devices such as mobile phones, digital camera, GPS navigation devices and tablet computers.

§  Floppy Disk (FD): It is a disk storage medium composed of a disk of thin and flexible magnetic storage medium, sealed in a rectangular plastic carrier lined with fabric that removes dust particles.

§  Optical Storage: It stores the information in deformities on the surface of a circular disc and reads this information by illuminating the surface with a laser diode and observing the reflection. There are four types of optical storage media which are as follows:


(i)   Compact Disc (CD): It is an optical disc used to store digital data.

(ii) Digital Versatile Disc (DVD): It is an optical disc storage format. DVDs offer higher storage capacity than compact disks while having the same dimensions.

(iii) Blue-ray Disc (BD): It is an optical disc storage medium designed to supersede the DVD format. The term Blue-ray is used to refer the blue laser, which is used to read the disc.

(iv) Holographic Versatile Disc: It is an optical disc technology that can store 1 TB of data on an optical disc of 10 cm in diameter.

·         Other types of storage media are as follows:

§  USB Flash Drive: It is a data storage device that includes flash memory with an integrated Universal Serial Bus (USB) interface.

§  Tertiary Storage or Tertiary Memory: It provides a third level of storage and involves a robotic mechanism which will mount (insert) and dismount (remove) mass storage media according to the system's demand.


Central Processing Unit (CPU)

·         It is the brain of the computer. It handles all the instructions given to your computer.

CPU is divided mainly into three parts

(i)   Control Unit

(ii)   Arithmetic Logic Unit

(iii) Memory


Dual Core Technology

·         It basically consist of two processors running parallel to each other. Multicore is an expansion to the dual core technology which allows for more than two separate processors.



·         It is a set of instructions that directs the computer to process information.

It can be classified into four types:

(i)   System Software

(ii)   Utility software

(iii) Application software

(iv) General purpose software


System Software

·         An Operating System is the most important software that runs on a computer. It manages the computer's memory, processes and all of its software and hardware.


Job of Operating System

·         Process Management

·         Device Management

·         Memory Management

·         Application Program Interface


Types of Operating System

·         Real-time operating system

·         Multi-tasking and single-tasking operating system

·         Distributed operation system

·         Network operating systems


Some of the operating systems are as follows:

·         Disk Operating System (DOS): It is a single user, single tasking operating system with basic Kernel's functions and only one program at a time can run on it and only one program at a time can run on it.

·         UNIX: It is a multi-tasking, multi-user computer operating system that is widely used in work stations and servers.

·         GNU: It is a UNIX like computer operating system developed by the GNU project and a complete UNIX compatible software system.

·         Linux: It is a Unix like computer operating system assembled under the model of free and open source software development and distribution.

·         Mac OS: It is a line of open core graphical operating systems developed marketed and sold by Apple Incorporation. Unlike its predecessor, Mac OS is a UNIX based operating system.

·         Microsoft Windows: It is a graphical interface operating system developed, marketed and sold by Microsoft.

·         Windows 10: Released in July 2015, Windows 10 is a computer operating system, having universal application architecture can be run across PCs, tablets, small phones, Xbox One, etc.

·         Windows Server 2012: Formerly code named Windows Server 8, it is the current release of Windows Server. It is a network operating system.

·         Android: It is an operating system based on Linux and designed primarily for touch screen mobile devices such as smart phones and tablet computers. Initially, it was developed by Android Inc. which Google bought in 2005.


Language Translator

·         Assembler: An assembler translate the symbolic codes of programs of assembly language into machine language.

·         Compiler: It is a program that translates whole source program written in some high level language into machine code at a time.

·         Interpreter: A program that executes the instructions written in a high level language into machine code as line by line instructions.



·         MANTRA Rajbhasha is a Machine Assisted Translation Tool, which translates documents pertaining to Personnel Administration, Finance, Small Scale Industries, Agriculture, Information Technology, Health Care, Education and Banking domains from English to Hindi.


Utility Software

·         Utility software helps to manage, maintain and control computer resources. Examples of utility software are as follows:

§  Antivirus software

§  Disk tools

§  Backup software


Application Software

·         It is user denned specific of computer software that employs the capabilities of a computer directly to a task that the user wishes to perform.


General Purpose Software

·         A general purpose software would be anything that aids in allowing user to accomplish simple computer related task.


Computer Networks

Local Area Network (LAN)

·         It is a computer network covering a small physical area (one km or less) like a home, office or small groups of buildings, such as school or an airport.


Metropolitan Area Network (MAN)

·         It is a larger computer network that usually spans a city or a larger campus (5 to 15 km).


Wide Area Network (WAN)

·         It is a computer network that covers a broad area (i.e. any network whose communications links cross metropolitan, regional or national boundaries).


Personal Area Network (PAN)

·         It is the interconnection of information technology devices or gadgets within the environment of an individual user. (typically within 10 metres).


Wireless Personal Area Network

·         It is a PAN carried over wireless network technologies such as Infrared Data Association (IrDA), Bluetooth, Wireless USB, Z-Wave, ZigBee or even Body Area Network.


Body Area Network

·         It is the application of wearable computing devices. It enables wireless communication between several miniaturised body sensor units, worn on human body.


Virtual Private Network (VPN)

·         It is a technology for using the internet or another intermediate network to connect computers to isolated remote computer networks that would otherwise be inaccessible.


Ethernet Networking

·         It provides the local area networking technology that has spread the Internet throughout our offices and cities.



·         It comprises non-interactive communication of text, data, image or voice messages between the sender and a particular recipient through systems using telecommunication connections. The messages are from machine to machine, and sender and recipient need not be online with each other - much cheaper than fax or telex.



·         VoIP stands for Voice over IP, where IP refers to the Internet Protocol that underlies all Internet communication. This phenomenon began as an optional two-way voice extension to some of the Instant Messaging systems that took off around the year 2000. In recent years, many VoIP systems have become as easy to use and as convenient as a normal telephone.

·         The benefit is that, as the Internet carries the actual voice traffic, VoIP can be free or cost much less than a normal telephone call, especially over long distances and specifically for those with always-on ADSL or DSL Internet connections.

·         Thus, VoIP is maturing into a viable alternative to traditional telephones. Interoperability between different providers has improved and the ability to call or receive a call from a traditional telephone is available. Simple inexpensive VoIP modems are now available that eliminate the need for a PC.

·         Voice quality can still vary from call to call, but is often equal to and can even exceed that of traditional calls.

·         Remaining problems for VoIP include emergency telephone number dialling and reliability. Currently a few VoIP providers provide some 911 dialling, but it is not universally available. Traditional phones are line powered and operate during a power failure, VoIP does not do so without a backup power source for the electronics.

·         Most VoIP providers offer unlimited national calling but the direction in VoIP is clearly towards global coverage with unlimited minutes for a low monthly fee.



·         Computer is an electronic device that can count, write and solvecomplex problems with high accuracy and speed.

·         3rd Generation of Computers: With advent of IC mini and microcomputers, \[{{10}^{8}}\] operations/sec-processing speed is possible, e.g. IBM-360, CDC 6000/7000.

·         4th Generation of Computers: They use LSI-Large scale IC and VLSI - very large scale IC. They are super computers, e.g. CRAY- XMP, FLOSOLVER, PARAM.

·         5th Generation of Computers: With artificial intelligence (to think like human beings).




What is computer simulation technique?

·         To simulate a phenomenon, on a computer or otherwise, we need a mathematical model that imitates the phenomenon. Such a model can be obtained, if we understand the basic principles involved.

·         As an example consider the motion of the Earth around the Sun. The Sun and the Earth attract each other. Once we know or model this gravitational force, we can simulate the elliptic orbit of the Earth.

·         Here we do not need a computer since the governing equation is simple.

·         But consider a slightly more complicated problem 'of a projectile hurled in the atmosphere. Here the friction of air comes into picture. It is a complicated function of the shape of the projectile, its orientation and velocity (last two are not known).

·         The trajectory can be simulated by approximate numerical techniques. We start with the condition of the projectile (position and velocity; then frictional force is known) at some instant. We can calculate its condition after a very small time interval.

·         Then the new value for friction can be evaluated. We continue this process of numerical integration to get the trajectory. The smaller the time interval employed, the more accurate is the solution.

·         This is where the computer enters, which can do the four basic arithmetical operations at a high speed and without mistakes.

·         Digital computers entered the scene in the mid-20th century and have become powerful tools in simulating different physical phenomena.

·         The complicated equations governing a phenomenon are approximated by a large system of simultaneous equations. The role of the computer is to solve this system of equations. The methods to solve simultaneous equations are known for centuries.

·         But we did not know even at the beginning of the 20th century whether these methods would lead to the accurate solution if the system contains, say 40 equations.

·         The more the number of equations, the better is the simulation but the effort required by the computer would be more.

·         Today millions of equations are solved literally millions of times, thanks to the good algorithms and powerful computers.

·         Complex fluid flow phenomena like turbulent flows, vibration of an aeroplane frame, combustion, weather, ocean circulation, chemistry of drug design, micro-electronics, nano-technology, economic modelling, formation of cosmic structures are some of the examples that need huge computing power.

·         Hence, we hear the words super computers, parallel computation, high performance computing, tera-flops (1,000 billion arithmetical operations per second; yes!), etc. Today there are supercomputers delivering dozens of tera-flops.

·         But the power we have on desktop machines today was available only with supercomputers a decade or so before.

·         Computer simulation leads to a large volume of information. Then we need facilities to store it and also tools to analyse and understand.



·         The invention of Germanium transistor way back in June 1946 was the starting point of microelectronics technology. In late 1960s, a thinking that integrated circuit can act as brain to different products, gained ground resulting in the birth of microprocessor 4004 in 1971.

·         The late 90s saw system on chip at 0.18 microns - 180 nanometres. Thus, between 1940s and 1950s, the semiconductor technology emerged from R&D laboratories.

·         Experts predict that the microelectronics manufacturing processes will not be cost effective beyond 2015. Beyond this, it is impossible to visualise at the present rate of growth, any large and cost effective usefulness for this technology.

·         The future of computing technologies lies in nanotechnology. There are five critical areas that hold promise.

·         Nanofabrication: Carbon nanotubes are an exotic variation of common graphite having super strength, low weight, stability, flexibility, large surface area, etc.

·         Potential applications include transistors and diodes, field emitter for flat-panel displays, cellular-phone signal amplifier, ion storage for batteries and materials strengthener.

·         Nano-electro mechanical systems [NEMS] are being developed for heterogeneous assembly in business sectors including medical optical assemblies, telecommunications, consumer electronics, microfluidics, defence and space needs.

·         Chemically assembled electronic nanotechnology is another emerging area. This uses self-alignment to construct electronic circuits out of nanometer scale devices that take advantage of quantum-mechanical effects.

·         Biocomputing: Cross-fertilisation of biotechnology with Information Technology reveals the inherent formation theories of natural life sciences with high-end computational techniques. Efforts have been made to compile full genetic information stored in the nucleus and the mitochondria as digital repositories of information.

·         Genomics is the main constituent of bioinformatic research that aims to decipher code of life in its fundamental unit, a cell.

·         Molecular computing: Researchers had built an electronic switch consisting of a layer of several million molecules of an organic substance called rotaxane.

·         By linking a number of switches, the researchers produced a rudimentary version of an AND gate. One of the simplest active devices was a molecular based on a string of 3 benzene rings in which orbitals overlapped throughout.

·         Optical computing: In optical computers, electrons are replaced by photons. Thus, it is possible to fabricate closely packed nanostructures.

·         Researchers are using new conducting polymers to make transistor like switches smaller and 1,000 times faster than silicon transistors.

·         There are a number of proteins, which are sensitive to light and change their structures/orientation depending on the wavelength of the light.

·         Bacteriorhodopsin obtained from green algae has been used for writing and reading information using laser beams of different wavelengths.

·         Quantum computing: Quantum computing aims to apply specific aspects of quantum theory in the development of the new systems and techniques for information processing.

·         By employing the extraordinary properties of quantum mechanical operations, such as superposition, entanglement, complementarity and uncertainty, data can be encoded in the quantum states of matter or light and manipulated with unprecedented speed and efficiency.

·         This emerging technology can revolutionise information processing, providing novel methods of securing, processing, storing, retrieving and transmitting information.

·         Practical applications could include super fast computers operating at the sub-atomic scale, and fully secure information transmission.



What is an Optical Disc?

An optical disc is a flat circular, usually polycarbonate disc whereon digital data such as music or text is stored in the form of pits or bumps within a flat surface. This data is accessed with the help of a laser and ray, that is why it is called optical disc. The reflected laser light gets distorted on reflection from pitted surface and such distortions are deciphered by a software programme.

Example: Optical discs include, Compact Discs (CD and CD ROM's), LASER Discs, Digital Versatile Discs (DVD and DVD ROM's), etc.

What are the different generations of optical discs?

·         First Generation O.D.: Optical discs were initially used for storing music and software, e.g., CD's, Laser disc.

·         Second Generation O.D.: They were created to store large amount of data including TV quality Digital Videos, e.g., DVD, Mini discs.

·         Third Generation O.D.: They are currently in development. They will be optimal for storing high definition videos and large video game software, e.g., Sony Playstation, Blue Ray Disc, High Definition DVD.



·         Google Earth is a new mapping service launched by Google that uses local search and satellite images to give users a three-dimensional view of buildings and terrain.

·         Google Earth lets people search for a location either their own neighbourhood or of the far comers of the globe, enabling users to get an aerial view, then zoom into see 3D images of certain buildings and landscapes.

·         Google earth utilises 3D graphics and broadband streaming technology, much like a videogame, offering dynamic navigation enabling users to interactively explore the world.

·         We can see the roof top of ALS Institute and then can navigate to see roof top of Batra Cinema with the help of Google Earth. We can also see 3D view of Qutub Minar.



·         Identity theft or identity fraud are terms used to refer to all types of crime in which someone wrongfully obtains and uses another person's personal data in some way that involves fraud or deception, typically for economic gain.

·         "But he that niches from me my good name

Robs me of that which not enriches him

And makes me poor indeed." Shakespeare, Othello.


How is identify theft done?

Our personal data such as our

·         Social security number

·         Bank account number

·         Credit card number

·         Telephone calling card numbers

and other valuable identifying data can be used, if they fall into wrong hands to personally profit at our expense. Not only economic losses are incurred but also the reputation in the community is lost.


How do criminals get such information?

The criminals get secret data by

(i)   Rummaging through rubbish

(ii)   Eavesdropping

(iii) Phising

(iv) Spams etc


How should we protect ourselves from identity theft?

The golden rules are

·         Don't give information easily without interrogation

·         Don't give credit cards numbers etc on telephone, e-mails, voicemails, etc

·         Keep in touch with credit card companies if the bills fail to come

·         Choose difficult and different passwords for different uses.



·         The computing in which the information carried in the computer chips is by photons rather than electrons is called optical computing.

·         The light is made up of small particles called photons which have zero mass and no charge.

·         The optical computers have microchips and other parts which primarily use light as medium of information exchange.


Why is optical computing necessary?

·         With the rapid growth of computers in various applications of daily life, efforts are on to make them deliver at high speed and to make them smaller in size.

·         In this regard, the electronic computers are now reaching their saturation. They are limited not only by the speed of electrons but also by increasing the density of interconnections on microchips.

·         The solution to this problems lies with the optical computing in the long run.


Why are optical computers faster?

·         The photons that travel at 3,000 km/sec are the fastest medium to carry signals. The limitation produced by slow moving electrons in electrical circuit can be solved by photons.

·         The optical data processing can perform many operations simultaneously (in parallel) much faster and easier than electronic one. The parallel processing when associated with fast switching speeds would produce staggering computational power. Bill Gates advocates that a calculation that might take 11 years for conventional computer to solve may be solved in just a single hour by optical computer.



Interactive TV is a convergence technology that will convert the one-way passive TV viewing into a two-way interactive experience. This technology would enable television viewers to access remote servers and internet through their TV and digital set top device. Or in other words, interactive TV is any television with a 'return path' i.e. information flows not only from broadcaster to viewer, but also back from viewer to broadcaster. This return path can be by telephone, mobile SMS or cable lines.


Different forms/configurations of ITV

ITV has been conceived in several different forms and configurations out of which three are very important.


1. Interactivity with a TV set: It is the most basic level of interaction. Here, the viewer can interact with the broadcaster and can control the viewing of television content.

Example: VCR like functions, e.g. pause, rewind, fast forward, commercial skipping and Video on Demand (VOD)


2. Interactivity with TV programme content: Here, the idea is that the programme itself, might change based on viewers' input.

Example:  i. Home shopping channels

   ii. Opinion polls

   iii. SMS voting

   iv. Choosing angle to watch football match


3. Interactivity with content that is related to what is on TV: It is also known as coactivity. It includes getting more information about what is on the TV, whether sports, movies, news, etc.

Example: While watching a movie, just press a button to get all the details of the movie, the title, the star cast, the director, the story. In a nutshell, viewer can get more information about what is being advertised, along with ability to buy it known as the duration in minutes, the number of minutes you have missed and the upcoming movie.


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Notes - Computer and Electronics

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