Notes

WHAT IS ICT?

·       Information and Communication Technologies (ICTs) is a broader term which include Information Technology (IT) and Communication Technologies (CT).

·       Information Technology (IT) is the use of computers to store, retrieve, transmit, and manipulate data, or information, often in the context of a business or other enterprise. IT system is generally an information system, a communications system or, more specifically speaking, a computer system – including all hardware, software and peripheral equipment – operated by a limited group of users. The term is commonly used as a synonym for computers and computer networks, but it also encompasses other information distribution technologies such as television and telephones. IT is considered to be a subset of Information and Communication Technology (ICT).

·       Communication Technology (CT) refers to the use of technology for telecommunication, broadcasting media, audio-visual processing, and for transmitting information through wired or wireless networks. It includes the internet, wireless networks, phones, and so on. Using these we can have real-time interactions in the form of chats, voice and video calls, even with people at geographically distant places.

·       ICT includes all communication technologies, including the internet, wireless networks, cell phones, computers, software, middleware, video-conferencing, social networking, and other media applications and services enabling users to access, retrieve, store, transmit, and manipulate information in a digital form. The processed data is known as information.

COMPUTER SYSTEM

A computer system operates in the followings ways;

·       A tool that takes commands and returns data.

·       A collection of components that take in electrical signals and returns electrical signals.

·       A device for converting characters to binary code.

·       A component in an office workflow diagram.

Computer is an advanced electronic device that takes raw data as input from the user, processes these data under the control of set of instructions (called program), gives the result (output), and saves output for the future use. It can process both numerical and non-numerical (arithmetic and logical) calculations.

A computer has four functions:

1.     Input (Data): Computer input is whatever entered or fed into a computer system. Input can be supplied by a person (such as by using a keyboard) or by another computer or device (such as a CD-ROM or a USB drive). Some examples of input include the words and symbols in a document, numbers for a calculation, instructions for completing a process, pictures etc.

2.     Processing: Data can be manipulated in many ways. This manipulation is called processing. Examples of processing include performing calculations, sorting lists of words or numbers, modifying documents and pictures according to user instructions, and drawing graphs. A computer processes data in the CPU. Process is a systematic series of actions a computer uses to manipulate data.

3.     Output: 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.

4.     Store result: A computer must store data so that it will be available for processing. Most computers have more than one location for storing data (the hard drive or C:∖ and the floppy drive or CD or USB). The place where the computer stores the data depends on how the data is being used. The computer puts the data in one place while it is waiting to be processed and another place when it is not needed for immediate processing. The storage of data in the computer is called ‘online storage’ while the storage of data on computer tapes, diskettes or CD-ROMs is called ‘offline storage’.

All of the components of a computer system can be summarized with a simple equation:

Computer system = Hardware +Software+ User.

·       Hardware = Internal Devices + Peripheral Devices

·       All physical parts of the computer (or everything that we can touch) are known as Hardware.

·       Software = Programs

·       Software gives intelligence to the computer.

·       USER = The person who operates computer

TYPES OF COMPUTERS

·       Generations of computer

·       On the Basis of Operation

1.     Analogue Computer

Analogue computers are designed to process analogue data. Analogue computers are used where we don't need exact values always. Analogue computers directly accept the data from the measuring device without first converting it into numbers and codes. They measure the continuous changes in physical quantity and generally render output as a reading on a dial or scale. Speedometer and mercury thermometer are examples of analogue computers. One of the types in analogue computer is Electronic Analogue Computer. In this type of analogue computer, electrical signals flow through capacitors and resistors to simulate physical phenomena. Here, the mechanical interaction of components does not take place. The voltage of the electrical signal generates the appropriate displays.

2.     Digital Computer

Digital computer is designed to perform calculations and logical operations at high speed. It accepts the raw data as input in the form of digits or binary numbers (0 and 1) and processes it with programs stored in its memory to produce the output. All modern computers like laptops, desktops including smartphones that we use at home or office are digital computers.

Advantages of digital computers:

·       It allows you to store a large amount of information and to retrieve it easily whenever you need it.

·       Additional features to digital systems can be done easily.

·       Different applications can be used in digital systems just by changing the program without making any changes in hardware

·       The cost of hardware is less due to the advancement in the IC technology.

·       It offers high speed as the data is processed digitally. It is highly reliable as it uses error correction codes.

3.     Hybrid Computer

Hybrid computer has features of both analogue and digital computer. It is fast like an analogue computer and has memory and accuracy like digital computers. It can process both continuous and discrete data. It accepts analogue signals and convert them into digital form before processing. So, it is widely used in specialized applications where both analogue and digital data is processed. For example, a processor is used in petrol pumps that converts the measurements of fuel flow into quantity and price. Similarly, they are used in airplanes, hospitals, and scientific applications.

·        On the Basis of Size

1.     Supercomputer

Supercomputers are the biggest and fastest computers. They are designed to process huge amount of data. A supercomputer can process trillions of instructions in a second. It has thousands of interconnected processors. Supercomputers are particularly used in scientific and engineering applications such as weather forecasting, scientific simulations and nuclear energy research. Roger Cray developed the first supercomputer in 1976. As of June 2020, the Cray XC40-based Pratyush is the fastest supercomputer in India. Another supercomputer is PARAM and MIHIR. PARAM is a series of supercomputers designed and assembled by the Centre for Development of Advanced Computing (C-DAC) in Pune, India. As of November 2020, the latest and fastest machine in the series is the PARAM Siddhi AI which ranks 63rd in world. The series includes - PARAM 8000, PARAM 8600, PARAM 9000, PARAM 10000, PARAM Padma, PARAM Yuva, ParamYuva II, PARAM ISHAN, PARAM Brahma, PARAM Sidhhi-AI.

Some other examples of supercomputers are:

ü  Summit, Oak Ridge National Laboratory (USA) ...

ü  Sierra, Lawrence Livermore National Laboratory (USA) ...

ü  Sunway TaihuLight, National Supercomputing Centre (Wuxi, China) .

ü  Tianhe-2A, National Supercomputing Centre (Guangzhou, China) .

ü  Frontier, Texas Advanced Computing Center, University of Texas (USA)

2.     Mainframe computer

Mainframe computers are designed to support hundreds or thousands of users simultaneously. They can support multiple programs at the same time. It means they can execute different processes simultaneously. These features of mainframe computers make them ideal for big organizations like banking and telecom sectors, which need to manage and process high volume of data. ATM machines are best example for mainframe computer.

3.     Miniframe or Minicomputer

It is a midsize multiprocessing computer. It consists of two or more processors and can support 4 to 200 users at one time. Miniframe computers are used in institutes and departments for tasks such as billing, accounting and inventory management. A minicomputer lies between the mainframe and microcomputer as it is smaller than mainframe but larger than a microcomputer.

A minicomputer is mainly used to perform three primary functions, which are as follows:

Process Control: It was used for process control in manufacturing. It mainly performs two primary functions that are collecting data and feedback. If any abnormality occurs in the process, it is detected by the minicomputer and necessary adjustments are made accordingly.

Data Management: It is an excellent device for small organizations to collect, store and share data. Local hospitals and hotels can use it to maintain the records of their patients and customers respectively.

Communications Portal: It can also play the role of a communication device in larger systems by serving as a portal between a human operator and a central processor or computer.

4.     Workstation

Workstation is a single user computer that is designed for technical or scientific applications. It has a faster microprocessor, a large amount of RAM and high speed graphic adapters. It generally performs a specific job with great expertise; accordingly, they are of different types such as graphics workstation, music workstation audio and video creation and editing also in engineering design workstation.

5.     Microcomputer

Microcomputer is also known as a personal computer. It is a general-purpose computer that is designed for individual use. It has a microprocessor as a central processing unit, memory, storage area, input unit and output unit. Laptops and desktop computers are examples of microcomputers. They are suitable for personal work that may be making an assignment, watching a movie, or at office for office work. Generally, comes with single semiconductor chip.

It is capable of multitasking such as printing, scanning, browsing, watching videos, etc. our desktop and laptops are the best examples of minicomputer.

COMPONENTS OF A COMPUTER SYSTEM

Every computer system has the following three basic components:

1.     Input Unit:

·       These components help users enter data and commands into a computer system. Data can be in the form of numbers, words, actions, commands, etc. The main function of input devices is to direct commands and data into computers. Computers then use their CPU to process this data and produce output.

·       For example, a laptop’s keyboard is an input unit that enters numbers and characters. Similarly, even a mouse can be an input unit for entering directions and commands. Other examples include barcode readers, Magnetic Ink Character Readers (MICR), Optical Character Readers (OCR), etc. Another example of input devices is touch-screens. Users can simply touch these screens without using any other device to enter commands. From smartphones to ATM machines, these input devices are becoming very popular these days.

a)     Keyboard: It is used for typing data and instruction. When a key is pressed on the keyboard, the character corresponding to the key gets typed on the screen. Keyboards have alphanumeric keys, function keys, navigation keys, punctuation keys, and other system keys. The keyboard of earlier PC had 84 keys. The most commonly used keyboards have 101 or 104 keys. The different keyboard layouts are QWERTY, QWERTZ, AZERTY, and DVORAK. These are available in wired and wireless models. Onscreen keyboards can also be used to prevent loss of information as there have been instances where the pattern of key press on the keyboard gets recorded.

b)    Mouse: It is a pointing device which controls the cursor as per its movements on a flat surface. It is important for working with graphical user interface (GUI). It can be used to select items, click on buttons, draw shapes and lines, etc. A mouse has left and right buttons which are used for left and right click respectively for performing different functions.

c)     Trackball: It has a ball with only its one half inserted inside the device and the cursor moves on the screen with the movement of the rolling of this ball. It is not movable like mouse.

d)    Digitizer or graphical tablet: It is used for drawing and writing just like we write on paper. When user draws on the digitizer, it also gets drawn on the screen.

e)     Touchpad: It is a touch sensitive pad on laptops the pointer on screen can be moved by moving the fingers on the touchpad. It also has a left and right button like the mouse

f)     Touchscreen: It is used to feed data and instruct by tapping the screen with fingers or a stylus. When you tap on an app icon on your smartphone, you are instructing it to open the app.

g)    Joystick: It is like a stick with balls at upper and lower ends. It is moved in different directions to move the cursor on the screen. It is used for playing games, navigating planes in flight simulators, car driving simulators, etc.

h)    Light pen: It is a pointing device like a pen which is used to select items, draw pictures, write on screens, etc. It works like a touch screen but has greater accuracy.

i)      Scanner: It is used to save data in digital form in the computer. The scanned data will be saved as image. Text recognition tools can be used to detect text in the scanned image. 'Handheld scanners' and 'flatbed scanners' can be used depending upon the need and availability of resources Smartphone cam era can also be used to scan files. Three-dimensional scanners can be used to scan real objects and analyse their appearance. Then three-dimensional models can be created on the basis of this analysis using three-dimensional printers. Fingerprint scanners are used to scan and verify the fingerprints and thumb impressions for authenticating the user identity. The new versions of laptops and smartphones have fingerprint scanners. These are also used for recording attendance in schools, colleges, organizations, departments, etc.

j)      Barcode reader: It is also a type of scanner which reads the barcode. These are used to load product information at stores.

k)    Webcam: It is a camera connected to the computer and can be used for sharing video input in video calls, videoconferencing, and live sessions. It can also be used to click photos. Similarly, digital cam eras can also be used.

l)      Microphone: It is used for providing audio inputs. It is useful for voice typing, narration, voice calls, audio recording, or for giving commands to Alexa, Siri, and Google Assistant, etc. It is also required along with webcam in video calls for the audio input.

2.     Central Processing Unit (CPU)

The Central Processing Unit (CPU) is called "the brain of computer" as it controls operation of all parts of computer. After receiving data and commands from users, a computer system now has to process it according to the instructions provided. Here, it has to rely on a component called the central processing unit. The CPU further uses these three elements:

·       Memory Unit

Once a user enters data using input devices, the computer system stores this data in its memory unit (RAM, ROM and HDD). This data will now remain here until other components of CPU process it. The memory unit uses a set of pre-programmed instructions to further transmit this data to other parts of the CPU. This is unit in which data and instructions given to computer as well as results given by computer are stored. Unit of memory is "Byte". [1 Byte = 8 Bits]

·       Arithmetic and Logic Unit (ALU)

This part of the CPU performs arithmetic operations. It does basic mathematical calculations like addition, subtraction, division, multiplication, etc. Further, it can even perform logical functions like the comparison of data and once again data is moved to RAM after process.

·       Control Unit

This unit is the backbone of computers. It is responsible for coordinating tasks between all components of a computer system. The control unit collects data from input units and sends it to processing units depending on its nature. Finally, it also further transmits processed data to output units for users.

Ø  The central processing unit (CPU) is the heart of the computer. It carries out all of the instructions given in a program, such as a word processing or spreadsheet program. The CPU consists of one or more chips (Intel or AMD). A chip or processor (another name for integrated circuits) is a small piece of semi-conducting material (such as silicon) about 1 centimetre (inch) square on which an integrated circuit is embedded. An integrated circuit is a number of electronic components joined together to form a path for electricity. Central processing unit chips contain the circuits representing the CPU. These processors are not equal. Some process data faster than others.

Ø  A computer contains a system clock that emits pulses to establish the timing of all systems operations. The system clock operates at a speed quite different from a clock that keeps track of the time of the day. The system clock determines the speed at which the computer can execute an instruction, and therefore limits the number of instructions the computer can complete within a specific amount of time. The time to complete an instruction execution cycle is measured in megahertz (MHz) or millions of cycles per second. Although some instructions require multiple cycles to complete, the processor speed should be thought of in terms of the number of instructions the processor can execute in one second.

3.     Output Unit

The third and final component of a computer system is the output unit. After processing of data, it is converted into a format, which humans can understand. After conversion, the output units display this data to users. Examples of output devices include monitors, screens, printers and speakers. Thus, output units reproduce the data formatted by the computer for users’ benefit.

a)     Monitor: It is also known as the visual display unit. It is used for displaying the output, video images, and other graphics. It helps in controlling and instructing the computer. Earlier, cathode ray tube (CRT) monitors were used. It had an aspect ratio of 4:3. Now, LCD and LED monitors are used these have an aspect ratio of 16:9. Sharpness of the screen depends upon the number of pixels, the tiny dots.

b)    Projectors: These are used to project images and graphics on canvas or wall. The projected image can be seen by a large number of people. These are usually used in classrooms, business meetings, presentations, etc. Overhead projectors can be mounted on the ceiling. Another model is the handheld projector.

c)     Printer: Printers are used to print the data a processed output. It can be directly connected the computer or shared over the network. Printer nowadays, have the features of accepting commands through Bluetooth or Wi-Fi connectivity. So printers support printing from phone using cable. There are different types of printers, like Matrix printer, Laser printer, Inkjet printer, Inktank printer. Dot matrix printers were the oldest among these. Laser printers use toners for printing. These have better performance but the toners are expensive. Inkjet printers use ink. These have better print quality than dot matrix printer but are less efficient than laser printers. Their ink is expensive. Printers can also be categorized as impact and non-impact printers. Impact printers print either a character or a line at a time; for example, dot matrix printer. Non-impact printers print a full page at a time. Laser and inkjet printers are examples of non-impact printers. Plotters are used for printing large sized posters, charts, blueprints, etc.

d)    Speaker and headphone: These are used to listen to audio. Some monitors have inbuilt speakers.

COMPUTER HARDWARE & SOFTWARE:

·       Computer hardware is any physical device, something that you are able to touch. For example, the computer monitor you are using to read this text on and the mouse you are using to navigate the web page are parts of computer hardware.

·       Software is a collection of instructions and code installed into the computer and cannot be touched. The Internet browser that allowed you to visit the web-page and the operating system that the browser is running on are software.

All computers require the following hardware components:

·       CPU (Central Processor Unit): The chip or chips at the heart of a computer that enable it to process data. Also known as a processor. It does the ‘work’, fetches, stores and manipulates values that are stored in the computer’s memory. Processors come in all different ‘shapes and sizes’ – there are many different types of architectures which are suited to a variety of different tasks.

·       Main memory (RAM-Random Access Memory): An area within a computer system that holds data waiting to be processed. It is used to store values during execution of a program. It can be written to and read from at any time.

·       Disc drive (HDD, CD /DVD, USB): Hard discs are generally located inside the machine and come in a variety of different sizes and speeds. They do not store files permanently. Compact Disk are another disk which store the data permanently while USB can store more data than CD and we can rewrite as much as we want. Now a days USBs and external Hard Disks are more common than CD and DVD.

·       VDU (Visual Display Unit): Visually outputs data. There are numerous types of VDU (LCD and CRT) differing in the resolution (dots per inch) and the number of colours that can be represented.

·       Printer: Allows a hard copy to be made. Again, there are different types of printers available, for example, line printers, dot-matrix printers, bubble jet printers and laser printers. These also differ in their resolution and colour palette.

MEMORY

A memory is just like a human brain. It is used to store data and instructions. Computer memory is the storage space in the computer, where data is to be processed and instructions required for processing are stored. The memory is divided into large number of small parts called cells.

Memory is primarily of three types −

1.     Cache Memory

2.     Primary Memory/Main Memory

3.     Secondary Memory

1.     Cache Memory

·       Cache Memory is a special high-speed memory. It is used to speed up and synchronizing with high-speed CPU.

·       Cache memory is an extremely fast memory type that acts as a buffer between RAM and the CPU. It holds frequently requested data and instructions so that they are immediately available to the CPU when needed.

·       Cache Memory is volatile in nature.

2.     Primary Memory/Main Memory

·       Primary memory is the main memory of the computer system. Accessing data from primary memory is faster because it is an internal memory of the computer. The primary memory is most volatile, which means data in primary memory, does not exist if it is not saved when a power failure occurs.

·       The primary memory is a semiconductor memory. It is costlier compared with secondary memory. The capacity of primary memory is very much limited and is always smaller compares to secondary memory.

·       Two types of Primary Memory are: RAM,ROM      

·       RAM (Random Access Memory): It is also called as read write memory or the main memory or the primary memory. The programs and data that the CPU requires during execution of a program are stored in this memory. It is a volatile memory as the data loses when the power is turned off. RAM is further classified into two types- SRAM (Static Random Access Memory) and DRAM (Dynamic Random Access Memory).

·       ROM (Read Only Memory): ROM is a permanent type of memory. Its content is not lost when the power supply is switched off. The computer manufacturer decides the information of ROM, and it is permanently stored at the time of manufacturing which the user cannot overwrite. Nonvolatile in nature.

Types of Read Only Memory (ROM) –

1.     PROM (Programmable read-only memory) – It can be programmed by user. Once programmed, the data and instructions in it cannot be changed.

2.     EPROM (Erasable Programmable read only memory) – It can be reprogrammed. To erase data from it, expose it to ultra violet light. To reprogram it, erase all the previous data.

3.     EEPROM (Electrically erasable programmable read only memory) – The data can be erased by applying electric field, no need of ultra violet light. We can erase only portions of the chip.

1.     Secondary Memory

·       The secondary storage devices which are built into the computer or connected to the computer are known as a secondary memory of the computer. It is also known as external memory or auxiliary storage.

·       The secondary memory is accessed indirectly via input/output operations. It is non-volatile, so permanently stores the data even when the computer is turned off or until this data is overwritten or deleted. The CPU can't directly access the secondary memory. First, the secondary memory data is transferred to primary memory then the CPU can access it.

·       Examples : Hard Disk Drive, CD, DVD, Pen Drive, Blu Ray Disk, SD Card

Hard Disk Drive

It is a rigid magnetic disc that is used to store data. It permanently stores data and is located within a drive unit. The hard disk is also known as a hard drive. It is a rigid magnetic disc that stores data permanently, as it is a non-volatile storage device. The hard disk is located within a drive unit on the computer's motherboard and comprises one or more platters packed in an air-sealed casing. The data is written on the platters by moving a magnetic head over the platters as they spin. The data stored on a computer's hard drive generally includes the operating system, installed software, and the user's files and programs, including pictures, music, videos, text documents, etc

CD Drive

CD stands for Compact Disk. CDs are circular disks that use optical rays, usually lasers, to read and write data. They are very cheap as you can get 700 MB of storage space. CDs are inserted in CD drives built into CPU cabinet. They are portable as you can eject the drive, remove the CD and carry it with you.

There are three types of CDs −

CD-ROM (Compact Disk – Read Only Memory): The data on these CDs are recorded by the manufacturer. Proprietary Software, audio or video are released on CD-ROMs.

CD-R (Compact Disk – Recordable): Data can be written by the user once on the CD-R. It cannot be deleted or modified later.

CD-RW (Compact Disk – Rewritable): Data can be written and deleted on these optical disks again and again.

DVD Drive

DVD stands for Digital Video Display. DVD are optical devices that can store 15 times the data held by CDs. They are usually used to store rich multimedia files that need high storage capacity. DVDs also come in three varieties – read only, recordable and rewritable

Pen Drive

Pen drive is a portable memory device that uses solid state memory rather than magnetic fields or lasers to record data. It uses a technology similar to RAM, except that it is nonvolatile. It is also called USB drive, key drive or flash memory.

Blu Ray Disk

Blu Ray Disk (BD) is an optical storage media used to store high definition (HD) video and other multimedia filed. BD uses shorter wavelength laser as compared to CD/DVD. This enables writing arm to focus more tightly on the disk and hence pack in more data. BDs can store up to 128 GB data

MEMORY UNITS

PROGRAMMING LANGUAGES

·       Language is important for communicating with anyone. Similarly, language is required in interaction with computers, for instructing computers, providing data, and receiving output. Computers languages are known as programming languages. A programming language is a formal language comprising a set of instructions that produce various kinds of output. Programming languages are used in computer programming to implement algorithms. BASIC, FORTRAN, PASCAL, C, C++, etc. are examples of programming languages. These are used to write programs for commanding the computer about what to do and how to do. Programs are like recipes with step-by-step instructions. A computer will not be able to work without programs. Programming languages can be categorized as follows:

Low-Level Languages

These are machine-oriented languages. It is difficult for humans to understand them. The two types of low-level languages are given below:

·       Machine language:

As name suggests it is the language which machines understand. It has only two digits, '0' and '1'. It is only understandable by machines and not humans. 'l' represents 'ON' and '0' represents OFF'. It is considered as the First Generation Language. If the programmer writes the program in this language, then it can be processed fast as no translation will be required. But due to its complexity and use of only two digits, the program mer has to remember many codes. There will be a high tendency of making errors and it will be dif ficult to detect those errors.

·       Assembly language

Assembly language uses symbols and keywords similar to the English language. So, it was easier to use as compared to machine language. Codes written in assembly language are not understandable by the computer which means these have to be converted. Assembly language was used in Second Generation Computers, hence known as Second Generation language. It was machine-specific, which means programs were based on the configuration of the computer. So, programs written for one computer might not work on another computer.

High-Level Languages

·       High-level languages are similar to English; these are easy to understand and use by humans. This means these are not machine-oriented. The codes in high-level languages are similar to the words which we use in our daily life. So, these are easy to use for programmers. However, it takes more time to execute as the programs need to be first translated before execution. Some examples of high level languages are COBOL (Common Business Oriented Language), BASIC (Beginners All purpose Symbolic Instruction Code), FORTRAN (Formula Translation), Pascal, Python, Java, etc.These languages are problem specific and have specific uses, that is, they are used for solving particular problems.

·       If two persons do not have a common language, then they will face problem in communicating with each other. Similarly, when the computer and humans do not understand a common language, then communication between them will be not be possible. For example, for the computer, '11' in binary numbers represents '2', but for us it is eleven. So, to overcome this problem translators like assemblers, compiler, and interpreter are required.

Language processors

·       Assemblers are used to translate assembly language code into a computer understandable form, that is, machine language. Similarly, compilers and interpreters are used to translate high-level languages to machine language. Compiler scans the program, then translate it in one go, and then executes it, while interpreter scans a statement, translate and execute it, and then moves to the next statement of the program. Language-specific compilers like FORTRAN compiler, Python Compiler are used for translating FORTRAN and Python, respectively. These translators also help in translating the output given by the computer into assembly language (by assembler), and high-level language (by compiler and inter- preter) for easy understanding of the user.

FILE FORMATS

VIDEO SIGNAL STANDARDS

·       There are three video signal standards, namely NTSC, PAL, and SECAM. Devices are manufactured according to the specifications of these signals. A PAL supporting device cannot receive NTSC signals.

Now, Standard-Definiton (SD), High-Definition (HD), Ultra High-Definition, etc. formats are used for high quality and better clarity of the video. The different HD formats are 720p, 1080i, 1080p, and 1440p. 4k, 8k are some examples of ultra HD.

NETWORK

·       Network refers to the connection between two or more computers for sharing information and resources like hardware, software, and database. Computers connected over a network can also share hardware like printers. Computers can be connected with the use of cables, or wireless mediums like waves, broadband, and satellite. The central device in a network is known as hub and the others are known as nodes. In Peer-to-Peer Network (P2P Network), all computers in the network have equal status. Servers in the network are computers that have the special role of providing services to other computers.

·       Server computers can be used for storing files (File Server), sharing common printer (Print Server), saving database (Database Server), sharing software and applications (Application Server), and for co-ordinating interactions (Message Server). Client computers or workstations avail the services of the server computers.

·       Networks involving clients and server are known as Client-Server Networks Uploading means sending files to the server and downloading is receiving files from the server Networking facilitates communication, allows sharing of files, information, and resources, etc.

The different types of networks are:

1.     PAN: PAN stands for Personal Area Network. It involves wired or wireless connection between different devices within a few metres. Examples include connecting phone and tablet through Bluetooth, or connecting phone with Bluetooth headphones, connecting printer with phone over Wi-Fi.

2.     LAN: LAN stands for Local Area Network. It is the network between computers of same building, room, or a campus of an institute. Computers can be connected through wires (coaxial cable) or wirelessly. WLAN stands for Wireless Local Area Network.

3.     CAN: Campus Area Network (CAN) is the interconnection of different LANS within a specific area like a campus.

4.     MAN: MAN stands for Metropolitan Area Network. It covers an area greater than LAN, but lesser than WAN. As the name suggests, it covers the area of about a city.

5.     WAN: WAN stands for Wide Area Network. It is used to connect computers which are at geographically distant places. Leased line, satellite, and other mediums are used in this network. It is cheaper and efficient to use. The modems which we have at our home, office, etc., for Wi-Fi are part of WAN.

Network Topologies

Network topology is the physical layout of the connection between computers. The different topologies are linear, bus, ring, star, tree, mesh, and hybrid (involving mix of topologies).

NETWORK THREATS

Malware, or “malicious software,” is an umbrella term that describes any malicious program or code that is harmful to systems.

Virus: These are pieces of software designed to spread from one computer device to another. Mostly they are downloaded from particular websites or sent as e-mail attachments with the intent of infecting your computer as well as other computers on your contact list through systems on your network. They can disable your security settings, send spam, steal and corrupt data from your computer, and even delete every single thing on your hard drive.

Worm: A computer worm is a type of malware that spreads copies of itself from computer to computer. A worm can replicate itself without any human interaction, and it does not need to attach itself to a software program in order to cause damage.

Spyware: Spyware is loosely defined as malicious software designed to enter your computer device, gather data about you, and forward it to a third-party without your consent.

Trojan Horse: In computing, a Trojan horse is a program downloaded and installed on a computer that appears harmless, but is, in fact, malicious. Unexpected changes to computer settings and unusual activity, even when the computer should be idle, are strong indications that a Trojan is residing on a computer.

Denial-of-Service Attack: A denial-of-service attempts to hinder legitimate users from accessing services or information from a website. It happens when malicious attackers overload a website with traffic. It is carried out by one computer and its internet connection, which may enable the intruder to access your credentials.

INTERNET

·       Internet is the network of networks. Websites are stored on World Wide Web (WWW) which is a virtual network.

·       Tim Berners-Lee invented WWW in 1989. Websites are designed using HTML, CSS, Javascript, PHP, etc. HTML files are readable by all browsers.

·       The web address of a webpage is known as URL (Uniform Resource Locator).

·       US Department of Defence started using ARPANET in 1969 for military purposes.

·       The different types of internet connections are Dial-up, DSL, Cable, Satellite, 3G, and 4G. at The internet can be used for checking weather forecasts, news updates, ordering food online, shopping online, making payments, watching videos, movies, and TV online, checking latest trends, connecting with people, navigating, checking traffic, listening to music and online radios, playing games, chatting, making voice or video calls, etc.

·       The user can also stream online radios and podcast, live sessions using Facebook, YouTube, Instagram, and other apps. Instant Messaging apps like WhatsApp, Facebook Messenger, Viber, Telegram etc. can be used for sending and receiving messages in real time. Students can access online educational channels, videos and other study materials.

Requirements for Internet Connection

These include modem, router, bridge, and gateway.

·       Modem is the short form of Modulator-Demodulator, which converts analog signals to digital signals and vice versa. Modems are used to connect computers with the internet.

·       Router: A router is a networking device that forwards data packets between computer networks. It performs the traffic directing functions on the internet. Routers are required for Wi-Fi. Some modems have built-in routers.

·       Repeater is a gadget that accepts, cleans, and retransmits electronic signals at a higher power level. Repeaters are required so that the signals can travel a longer distance without degrading.

·       Hub is a networking device to which multiple devices are connected through cables. The connected devices are known as ports. Fiber optic Ethernet cables are usually used for connections. Hub receives data and shares it with ports.

·       Switches connect ports to network segments. Like hubs, switches are used to receive and send data to ports. Switches are used for a large number of devices. They have better performance than hub. Hub shares data with all ports, while switches send it to only the intended port.

·       Bridges are networking devices that fragment the network to deal with traffic. It decreases blockage and ensures that speed doesn't drop drastically.

·       Brouters are networking devices which are a combination of routers and bridges.

·       Gateways are devices used for transmitting data from one network to another. These control traffic in the organization network or for Internet Service Provider.

·       Network Interface Cards (NIC) are installed on motherboard for connecting to the internet. It has the port for connecting the ethernet cable.

·       Network protocols: These are a set of rules which govern the network. These are:

1.     POP, IMAP: used for sending and receiving email

2.     TCP/IP: sending data over the internet

3.     HTTP: for webpages

4.     FTP: for transferring files

5.     SSL: for sending private documents via the internet

6.     TFTP: for transferring files between network devices

7.     SMTP: for sending mail

8.     Telnet: for connecting to remote host

·       HTML stands for Hyper Text Markup Language. It is used for designing webpages and websites.

·       SGML stands for Standardised General Markup Language. It is a meta language used for structuring documents.

·       URL stands for Uniform Resource Locator. It is e the address of a webpage.

·       Search engines are softwares used for searching information. When any word searched on a search engine, it will give a list of links related to it. Some of the popularly used search engines are Google, Yahoo, Bing, Baidu, and so on

·       Web browser, as the name suggests, are used for browsing websites. The user can fill in the address of the website or webpage in the address bar in browser, and then press enter to visit that page. The user can also search key words in browser. The commonly used web browsers are Safari, Google Chrome, Mozilla Firefox, Opera, Internet Explorer, etc. These web browsers are available for multiple operating systems such as Windows and Mac. Surfing the internet or web browsing is the act of browsing webpages, moving from one webpage to another, etc

·       Bandwidth is a measure of the network speed which determines how much data can be accessed within a specified time. With higher bandwidth, a file can be downloaded or uploaded faster as compared to a connection with lower bandwidth. It is measured in the number of bits that can be downloaded in a second Commonly used units are Kbps and Mbps. In analog networks, bandwidth is measured in Hertz (Hz).

·       Blog: The word Blog is derived from 'Web Log It is managed by individuals who share their experiences, guidelines, etc. There are blogs with educational content, makeup tutorials, food reviews, movie reviews, travel recommendations, etc. The posts in a blog are arranged chronologically in the reverse order.

·       IP address: An Internet Protocol address (IP address) is a numerical label assigned to each device connected to a computer network that uses the Internet Protocol for communication. An IP address serves two main functions: host or network interface identification and location addressing. An example of an IP address would be: 506.457.14.512

There are two IP versions: IPv4 and IPv6. IPv4 is the older version which has a space of over 4 billion IP addresses. However, the new IPv6 version can provide up to trillions of IP addresses to fulfill the need of all internet users and devices. The IPv4 version used to configure IP addresses in numerical value (numbers) which may conflict with other IP addresses. That’s why IPv6 adopted the hexadecimal method to provide unique IP addresses to billions of users in the world. Example of an IP address would be: 4ggr:1925:5656:7:600:t4tt:tc54:98vt

EMAIL

·       The full form of email is electronic mail. It is a letter or mail sent electronically using the computer and internet. Such mails get delivered within a few seconds if the receiver is also online. If the receiver is not online, then he will receive the mail whenever he is online. Documents, images, videos, gif, emoticons can be sent through email along with text. The sender and recipient need to have email accounts for sending and receiving mails. Emails can be sent for formal as well as informal communication.

From: This will have the email address of the sender.

To: This will be the email address of the recipient.

Subject: This shows the title of mail so that the receiver can have some idea about the mail before opening it. It helps in identifying spam or junk mails.

Cc: To send a carbon copy of mail to any other person, enter his email address in 'Cc' while sending the mail.

Bcc:There is one another field 'Bcc', which stands for Blind Carbon Copy. A Bcc recipient will be able to see the content and email addresses of other recipients, but others will not be able to see his address.

SOME IMPORTANT TERMS IN ICT

·       Netiquette: It relates to internet etiquettes. These are the unwritten rules which one should obey while using the internet. These tell about the acceptable online behaviour.

·       Phishing: It relates to cybercrime and online frauds. According to Oxford English Dictionary, phishing is the fraudulent practice of sending emails purporting to be from reputable companies in order to induce individuals to reveal personal information, such as passwords and credit card numbers'.

·       Sniffing is a process of monitoring and capturing all data packets passing through given network. Sniffers are used by network/system administrator to monitor and troubleshoot network traffic. Attackers use sniffers to capture data packets containing sensitive information such as password, account information etc. Sniffers can be hardware or software installed in the system. By placing a packet sniffer on a network in promiscuous mode, a malicious intruder can capture and analyze all of the network traffic.

·       Spoofing is coordinated attack against your network security when someone or something pretends to be someone or something they are not in an attempt to gain access to your systems, steal your data, or gain your confidence. An example of spoofing is when an email is sent from a false sender address, that asks the recipient to provide sensitive data. This email could also contain a link to a malicious website that contains malware.

·       Spamming is the use of messaging systems to send an unsolicited message (spam) to large numbers of recipients for the purpose of commercial advertising, for the purpose of non-commercial proselytizing, or for any prohibited purpose (especially the fraudulent purpose of phishing). While the most widely recognized form of spam is email spam.

·       A software bug is an error, flaw or fault in a computer program or system that causes it to produce an incorrect or unexpected result, or to behave in unintended ways. The process of finding and fixing bugs is termed "debugging".

·       ADSL: It stands for Asymmetric Digital Subscriber Line. It is a type of Digital Subscriber Line which is known for its high speed at lesser price with all-time connectivity using existing copper telephone wires. It is used as broadband at our homes and offices.

·       Adware: These are unwanted softwares that get installed in the computer along with any other software. These record data and create a profile which is then used to show advertisements as per items of your choice.

·       Al: Al stands for Artificial Intelligence which aims at developing intelligent machines. These intelligent machines will work, think, and react like humans. Self-driving cars, robotic machines, voice search, spam filters, mail categorization, plagiarism checker, Google Assistant, Siri, Alexa, etc., involve the use of Al.

·       ALU: ALU stands for Arithmetic Logic Unit. It executes the commands during processing.

·       Analog network: It is used for transmitting analog signals, i.e., continuously varying electric signals.

·       Antivirus software: These softwares are used to detect the presence of virus, trojans, and malwares in the system. After identifying the infected files, the program will ask the user to take further action. Antivirus programs, if installed, will notify the user whenever any suspicious activity is detected. Windows 7, 8, and 10 have pre-installed antivirus software named 'Windows Defender. Some other commonly used antivirus programs are Avast Antivirus, Kaspersky, Quick Heal, etc.

·       Applet: Applets are Java Programmed modules which are incorporated in HTML webpages. These are used to run applications.

·       ASCII: It stands for American Standard Code for Information Interchange. It converts the instructions and data in to binary form so that the computer can understand it.

·       Attachment Documents, spreadsheets, images, videos, and other files which are attached in a mail by sender are the attachments. An attachment of maximum size 25MB can be sent through gmail.

·       Baud rate: It was used to measure the rate of transfer of data through modem, cables etc. Now, Kbps and Mbps are usually used for measuring data transfer rate.

·       Beta testing: After developing an application or software and before finally launching it, it is tested by the potential customers. These customers have to report about the errors and give feedback. The software is then modified accordingly. Once the developers are satisfied with its performance, then it is final launched. This testing by customers is known as beta testing. Users have to register first for testing applications and softwares.

·       Biometric authentication: The traditional system of security involved the use of keys, passwords, etc. Such a system has loopholes and anyone having the key or password can log in or access. To overcome this, the new technology of security and identification involving the use of biometrics is used. The biometric profile of the user will be created and then the biometric scanned at the time of login has to be matched with the biometrics in the profile. Today, smartphones also have fingerprint scanners using which phones far be unlocked by scanning fingerprints. Similarly, face recognition, iris, hand, voice, etc. can be used for such kind of security system.

·       BIOS: The full form of BIOS is Basic Input-Output System. It is a built-in ROM chip on the motherboard It is used at the time of booting, as it has essential programs required for turning the computer on.

·       Bluetooth: It provides connectivity between phones, phone and computer, phone and headphones, etc. over a short distance (10 meters) Cables are not required for such connections. Using Bluetooth, data can be transferred from one device to another, audio output can be shared, files on another device can be accessed, etc.

·       Booting: It is the process of starting or restarting the computer. During booting, the files of operating system are executed. The processing at the time o switching on the computer is known as cold booting. When computer is restarted, it is known as hot or warm booting.

·       Bridge: It is a tool used to connect computers having the same communication protocol. It is necessary for connecting to the internet.

·       Burning CD: The process of writing data on a CD is known as burning the CD.

·       CSS: CSS stands for Cascading Style Sheets. These have all the details about the style of the website.

·       Cloud computing: It involves the use of internet for accessing files online. In our daily life, we make use of Google Drive, Dropbox, Banking, Online Shopping, live streaming etc. All these activities involve cloud computing.

·       Coaxial cable It is a cable used for data transmission. In a coaxial cable, a wire is placed in the centre and then an insulator and mesh wrap it.

·       Cookie: When a user visits a website, some information gets saved in his computer. This information is known as cookie. Cookies help in maintaining a record of your visits, saving information, etc. In online shopping, suppose you have put an item in your cart, then you close the browser and then open it again, you will see that the item is still in your cart. It is due to the cookies. Cookies are also used to show webpages and advertisements customized as per the choice of user.

·       Database: It is a file used for storing data and records on different variables and fields.

·       DBMS: DBMS stands for Database Management System. These are softwares used for creating, managing, and manipulating database. Some database management systems are Microsoft Access, Oracle, SQL server, and Filemaker.

·       DPI: DPI stands for dots per inch. It is a measure of quality of printer. It can also be used for monitors. Higher dpi implies better quality.

·       FTP: File Transfer Protocol, is used to transfer files from one computer to another.

·       Firewall It is an important feature of computer system which monitors the incoming and outgoing data packets over the network. It has the ability to block any suspicious packets.

·       FLOPS: The full form of FLOPS is Floating point operations per second. It is used to measure the performance of computers.

·       HTML: HTML stands for Hyper Text Markup Language.It is used for designing websites. A file with extension ‘html' can be opened in any web browser.

·       Hyperlink: It is like a reference with a link. Images and text can hyperlink to connect it with any other section of the webpage or document. On clicking the hyperlinked text, the link will open or document will shift to the other section as programmed by the developer.

·       Mac OS: It is the operating system developed and marketed by Apple Inc. It is used in Apple's computers, laptops (macbook), tablets (ipad), smartphones (iphone), etc.

·       MICR: MICR stands for Magnetic Ink Character Recognition. Characters printed with magnetic ink are recognized with special readers.

·       Open Source Softwares: It refers to the software which are available free of cost. Users do not have to pay any charges for using such software. Anyone can download these from the internet. VLC player, Apache, Mozilla Firefox, Linux, Ubuntu, etc., are examples of open source software.

·       Popup: It is a small window that appears on the screen while using websites. Users can block or allow popups from the browser settings.

·       RFID tag: Radio frequency identification tags are attached to products. These can store information for identification of products and can be read even from a distance by the reading devices wirelessly.

·       Safari: It is a web browser in Mac operating system developed by Apple Inc.

·       SPOOL: SPOOL is the short form of Simultaneous Peripheral Operations Online. Files sent for print gets temporarily saved for executing later depending on the availability of time

·       Spyware: This is similar to Adware. It is a type of malicious software that is installed on a computing device without the end user’s knowledge.

·       TCP/IP:  It stands for Transmission Control Protocol/ Internet Protocol, which is used for data transfer.

·       Vlog:  It is the short form of video blog.

·       VolP: It stands for Voice over Internet Protocol. It helps in sending voice or multimedia content over the IP network. The apps or websites, which we use for audio or video calls over the internet, are all based on VoIP. Examples include Skype, Facebook Messenger, WhatsApp, Viber, and so on.

·       Zipping is the process of compressing a file. A compressed file will have smaller size. Compressed files are easy to share as smaller files take lesser time.

COMPUTER AND INTERNET ACRONYMS