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Dr. Kajal Rai
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Computer Fundamentals A computer is an electronic data processing device, which accepts and stores data input, processes the data input, and generates the output in a required format.
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Functionalities of a Computer If we look at it in a very broad sense, any digital computer carries out the following five functions: Step 1 - Takes data as input. Step 2 - Stores the data/instructions in its memory and uses them as required. Step 3 - Processes the data and converts it into useful information. Step 4 - Generates the output. Step 5 - Controls all the above four steps.
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Data Processing The activity of processing data using a computer is called data processing.
Data is raw material used as input and information is processed data obtained as output of data processing. Dr. Kajal Rai 4
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Characteristics of Computers Automatic: Given a job, computer can work on it automatically without human interventions. Speed: Computer can perform data processing jobs very fast, usually measured in microseconds (10-6), nanoseconds (10-9), and picoseconds (10-12). Accuracy: Accuracy of a computer is consistently high and the degree of its accuracy depends upon its design. Computer errors caused due to incorrect input data or unreliable programs are often referred to as Garbage- In-Garbage-Out (GIGO)
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Characteristics of Computers Diligence: Computer is free from monotony, tiredness, and lack of concentration. It can continuously work for hours without creating any error and without grumbling. Versatility: Computer is capable of performing almost any task, if the task can be reduced to a finite series of logical steps. Power of Remembering: Computer can store and recall any amount of information because of its secondary storage capability. It forgets or looses certain information only when it is asked to do so.
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Characteristics of Computers No I.Q.: A computer does only what it is programmed to do. It cannot take its own decision in this regard. No Feelings: Computers are devoid of emotions. Their judgment is based on the instructions given to them in the form of programs that are written by us (human beings).
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Evolution of Computers Blaise Pascal invented the first mechanical adding machine in 1642 Baron Gottfried Wilhelm von Leibniz invented the first calculator for multiplication in 1671 Keyboard machines originated in the United States around 1880 Around 1880, Herman Hollerith came up with the concept of punched cards that were extensively used as input media until late 1970s
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Evolution of Computers Charles Babbage is considered to be the father of modern digital computers He designed “Difference Engine” in 1822 He designed a fully automatic analytical engine in 1842 for performing basic arithmetic functions His efforts established a number of principles that are fundamental to the design of any digital computer
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Some Well Known Early Computers The Mark I Computer (1937-44) The Atanasoff-Berry Computer (1939-42) The ENIAC (1943-46) The EDVAC (1946-52) The EDSAC (1947-49) Manchester Mark I (1948) The UNIVAC I (1951)
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Computer Generations “Generation” in computer talk is a step in technology. It provides a framework for the growth of computer industry. Originally it was used to distinguish between various hardware technologies, but now it has been extended to include both hardware and software. Till today, there are five computer generations.
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Computer Generations
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Computer Generations
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Computer Generations
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Computer Generations
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Electronic Devices Used in Computers of Different Generations
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Five Basic Operations of a Computer System
Inputting: The process of entering data and instructions into the computer system. Storing: Saving data and instructions to make them readily available for initial or additional processing whenever required. Processing: Performing arithmetic operations (add, subtract, multiply, divide, etc.) or logical operations (comparisons like equal to, less than, greater than, etc.) on data to convert them into useful information.
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Five Basic Operations of a Computer System
Outputting: The process of producing useful information or results for the user such as a printed report or visual display. Controlling: Directing the manner and sequence in which all of the above operations are performed.
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Basic Organization of a Computer System
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Input Unit
An input unit of a computer system performs the following functions: It accepts (or reads) instructions and data from outside world. It converts these instructions and data in computer acceptable form. It supplies the converted instructions and data to the computer system for further processing.
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Output Unit
An output unit of a computer system performs the following functions: It accepts the results produced by the computer, which are in coded form and hence, cannot be easily understood by us. It converts these coded results to human acceptable (readable) form. It supplies the converted results to outside world.
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Storage Unit
The storage unit of a computer system holds (or stores) the following : Data and instructions required for processing (received from input devices). Intermediate results of processing. Final results of processing, before they are released to an output device.
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Two Types of Storage
Primary Storage Secondary Storage
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Primary Storage
Used to hold running program instructions Used to hold data, intermediate results, and results of ongoing processing of job(s) Fast in operation Small Capacity Expensive Volatile (looses data on power dissipation)
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Secondary Storage
Used to hold stored program instructions Used to hold data and information of stored jobs Slower than primary storage Large Capacity Lot cheaper that primary storage Retains data even without power
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Arithmetic Logic Unit (ALU)
Arithmetic Logic Unit of a computer system is the place where the actual executions of instructions takes place during processing operation.
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Control Unit (CU)
Control Unit of a computer system manages and coordinates the operations of all other components of the computer system.
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Central Processing Unit (CPU)
It is the brain of a computer system It is responsible for controlling the operations of all other units of a computer system.
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The System Concept
A computer is a system as it comprises of integrated components (input unit, output unit, storage unit, and CPU) that work together to perform the steps called for in the executing program.
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Hardware
The term hardware refers to mechanical device that makes up computer. Computer hardware consists of interconnected electronic devices that we can use to control computer’s operation, input and output. Examples of hardware are CPU, keyboard, mouse, hard disk, etc.
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Hardware Components
Computer hardware is a collection of several components working together. Some parts are essential and others are added advantages. Computer hardware is made up of CPU and peripherals as shown in image below.
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Software
A set of instructions that drives computer to do stipulated tasks is called a program. Software instructions are programmed in a computer language, translated into machine language, and executed by computer. Software can be categorized into two types − System software Application software
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System Software
System software operates directly on hardware devices of computer. It provides a platform to run an application. It provides and supports user functionality. Examples of system software include operating systems such as Windows, Linux, Unix, etc.
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Application Software
An application software is designed for benefit of users to perform one or more tasks.
Examples of application software include Microsoft Word, Excel, PowerPoint, Oracle, etc.
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Differences between Software and Hardware
Software Hardware It is a collection of programs to bring It includes physical components of computer hardware system into operation. computer system. It includes numbers, alphabets, It consists of electronic components like ICs, alphanumeric symbols, identifiers, diodes, registers, crystals, boards, insulators, keywords, etc. etc. Software products evolve by adding new Hardware design is based on architectural features to existing programs to support decisions to make it work over a range of hardware. environmental conditions and time. It will vary as per computer and its built-in It is mostly constructed for all types of functions and programming language. computer systems. It is designed and developed by experienced The hardware can understand only low-level programmers in high-level language. language or machine language. The software is categorized as operating The hardware consists of input devices, system, utilities, language processor, output devices, memory, etc. application software, etc. It is represented in any high-level language The hardware works only on binary codes 1’s such as BASIC, COBOL, C,Dr. C++, Kajal RaiJAVA, etc. and 0’s. 35
Computer Registers
Registers are a type of computer memory used to quickly accept, store, and transfer data and instructions that are being used immediately by the CPU. The registers used by the CPU are often termed as Processor registers. A processor register may hold an instruction, a storage address, or any data (such as bit sequence or individual characters). The computer needs processor registers for manipulating data and a register for holding a memory address. The register holding the memory location is used to calculate the address of the next instruction after the execution of the current instruction is completed.
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Most Common Registers
Register Number of bits Function Data Register (DR) 16 Holds memory operand Address Register (AR) 12 Holds address for the memory Accumulator (AC) 16 Processor register Instruction Register (IR) 16 Holds instruction code Program Counter (PC) 12 Holds address of the instruction Temporary Register (TR) 16 Holds temporary data Input Register (INPR) 8 Carries input character Output Register (OUTR) 8 Carries output character
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System Bus A system bus is a single computer bus that connects the major components of a computer system, combining the functions of a data bus to carry information, an address bus to determine where it should be sent, and a control bus to determine its operation.
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Cache Memory 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 used to reduce the average time to access data from the Main memory.
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Inside a computer
Motherboard CPU/processor RAM (random access memory) Hard drive Power supply unit Expansion cards Video card Sound card Network card Bluetooth card (or adapter)
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Motherboard The motherboard is the computer's main circuit board. It's a thin plate that holds the CPU, memory, connectors for the hard drive and optical drives, expansion cards to control the video and audio, and connections to your computer's ports (such as USB ports). The motherboard connects directly or indirectly to every part of the computer.
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CPU/processor
The central processing unit (CPU), also called a processor, is located inside the computer case on the motherboard. It is sometimes called the brain of the computer, and its job is to carry out commands. A processor's speed is measured in megahertz (MHz), or millions of instructions per second; and gigahertz (GHz), or billions of instructions per second.
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RAM (Random Access Memory)
RAM is your system's short-term memory. Whenever your computer performs calculations, it temporarily stores the data in the RAM until it is needed. This short-term memory disappears when the computer is turned off. RAM is measured in megabytes (MB) or gigabytes (GB).
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Hard drive
The hard drive is where your software, documents, and other files are stored. The hard drive is long-term storage, which means the data is still saved even if you turn the computer off or unplug it. When you run a program or open a file, the computer copies some of the data from the hard drive onto the RAM. When you save a file, the data is copied back to the hard drive. The faster the hard drive, the faster your computer can start up and load programs.
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Power supply unit
The power supply unit in a computer converts the power from the wall outlet to the type of power needed by the computer. It sends power through cables to the motherboard and other components.
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Expansion cards
Most computers have expansion slots on the motherboard that allow you to add various types of expansion cards. These are sometimes called PCI (peripheral component interconnect) cards.
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Video card
The video card is responsible for what you see on the monitor. Most computers have a GPU (graphics processing unit) built into the motherboard instead of having a separate video card. If you like playing graphics-intensive games, you can add a faster video card to one of the expansion slots to get better performance.
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Sound card
The sound card—also called an audio card—is responsible for what you hear in the speakers or headphones. Most motherboards have integrated sound, but you can upgrade to a dedicated sound card for higher- quality sound.
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Network card
The network card allows your computer to communicate over a network and access the Internet. It can either connect with an Ethernet cable or through a wireless connection (often called Wi-Fi). Many motherboards have built-in network connections, and a network card can also be added to an expansion slot.
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Bluetooth card (or adapter)
Bluetooth is a technology for wireless communication over short distances. It's often used in computers to communicate with wireless keyboards, mice, and printers. It's commonly built into the motherboard or included in a wireless network card. For computers that don't have Bluetooth, you can purchase a USB adapter, often called a dongle.
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Switched-Mode Power Supply (SMPS) A switched-mode power supply (SMPS) is an electronic circuit that converts power using switching devices that are turned on and off at high frequencies, and storage components such as inductors or capacitors to supply power when the switching device is in its non-conduction state. Switching power supplies have high efficiency and are widely used in a variety of electronic equipment, including computers and other sensitive equipment requiring stable and efficient power supply.
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Advantages of switched-mode power supplies Higher efficiency of 68% to 90% Regulated and reliable outputs regardless of variations in input supply voltage Small size and lighter Flexible technology High power density
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Disadvantages Generates electromagnetic interference Complex circuit design Expensive compared to linear supplies
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Ports A port is a physical docking point using which an external device can be connected to the computer. It can also be programmatic docking point through which information flows from a program to the computer or over the Internet.
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Characteristics of Ports
A port has the following characteristics − External devices are connected to a computer using cables and ports. Ports are slots on the motherboard into which a cable of external device is plugged in. Examples of external devices attached via ports are the mouse, keyboard, monitor, microphone, speakers, etc.
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Serial Port
Used for external modems and older computer mouse Two versions: 9 pin, 25 pin model Data travels at 115 kilobits per second
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Parallel Port
Used for scanners and printers Also called printer port 25 pin model IEEE 1284-compliant Centronics port
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PS/2 Port
Used for old computer keyboard and mouse Also called mouse port Most of the old computers provide two PS/2 port, each for the mouse and keyboard IEEE 1284-compliant Centronics port
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Universal Serial Bus (or USB) Port
It can connect all kinds of external USB devices such as external hard disk, printer, scanner, mouse, keyboard, etc. It was introduced in 1997. Most of the computers provide two USB ports as minimum. Data travels at 12 megabits per seconds. USB compliant devices can get power from a USB port.
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VGA Port
Connects monitor to a computer's video card. It has 15 holes. Similar to the serial port connector. However, serial port connector has pins, VGA port has holes.
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Ethernet Port
Connects to a network and high speed Internet. Connects the network cable to a computer. This port resides on an Ethernet Card. Data travels at 10 megabits to 1000 megabits per seconds depending upon the network bandwidth.
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Modem Port
Connects a PC's modem to the telephone network.
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Ports and Interfaces
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High Definition Multimedia Interface (HDMI) High-Definition Multimedia Interface is an audio/video interface which transfers the uncompressed video and audio data from a video controller, to a compatible computer monitor, LCD projector, digital television etc.
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Ribbon Cable
A ribbon cable is a flat, thin cable composed of multiple small-grade cables placed parallel to each other. With each core situated side by side, they form a wide- flat cable resembling a piece of ribbon, hence its name. This type of cable is mostly used in electronic systems that require multiple data buses to link internal peripherals, such as disk drives to their respective drive controllers. Ribbon cables are also known as multiplanar cables.
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Memory Chip
A memory chip is an integrated circuit made out of millions of capacitors and transistors that can store data or can be used to process code. Memory chips can hold memory either temporarily through random access memory (RAM), or permanently through read only memory (ROM). Read only memory contains permanently stored data that a processor can read but cannot modify. Memory chips comes in different sizes and shapes. Some can be connected directly while some need special drives. Memory chips are essential components in computer and electronic devices in which memory storage plays a key
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Types of Memory Chips
DRAM SRAM FIFO EPROM PROM
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DRAM
Dynamic random access memory chips or DRAM chips is a memory cell requiring refreshing because it transits only single lines of memory. A DRAM chip has numerous small capacitors that contain each memory bit. DRAM chips do not hold change and need to be refreshed in order to keep the contents on the chips from being lost. DRAM chips are commonly referred to as volatile memory chips because they lose their memory when power is lost. DRAM chips are used in some computers that are constantly hooked to power supplies.
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SRAM
SRAM chips are static random access memory chips. SRAM chips are non-volatile memory chips and do not require refreshing or power to keep memory intact. SRAM chips are most common in portable battery powered devices like laptops, cameras, cell phones and video game consoles.
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FIFO
FIFO memory chips or First-In First-Out memory chips are used in applications that are used between different devices. The devices work at different speeds, so the FIFO memory chips are necessary to buffer the memory between the two devices. Flash or jump drives that are used to transport memory between different computers and types of computers use FIFO memory chips.
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EPROM EPROM chips are erasable programmable read- only memory. These types of memory chips can be erased when they are exposed to ultraviolet light. When erased, the ERPOM chips can then be reprogrammed to contain a new set of data or reused to house a different program. A variation of this type of memory chip is the EEPROM chip that can be erased electronically rather than with UV light.
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PROM
PROM chips are programmable read-only memory chips that differ from other programmable read-only memory chips because they can only be written to once. PROM chips cannot be erased with UV light or electronically.
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Devices Input Devices Output Devices
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Input device
In computing, an input device is a piece of equipment used to provide data and control signals to an information processing system such as a computer or information appliance.
Examples of input devices include keyboards, mouse, scanners, cameras, joysticks, and microphones.
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Keyboard
'Keyboard' is a human interface device which is represented as a layout of buttons. Each button, or key, can be used to either input a linguistic character to a computer, or to call upon a particular function of the computer. They act as the main text entry interface for most users. Traditional keyboards use spring-based buttons, though newer variations employ virtual keys, or even projected keyboards. Keyboards are of two sizes 84 keys or 101/102 keys, but now keyboards with 104 keys or 108 keys are also available for Windows and Internet.
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Mouse
A mouse is an input device that allows you to control the coordinates and movement of the onscreen cursor/pointer by simply moving the mouse across a flat surface with your hand. Items can be selected or moved using the left mouse button, whilst the right button usually displays additional menus. Most mice are now optical which means they use a laser to detect and track movement across the surface. Mice can be wired or wireless.
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Mouse
Typical applications for a mouse Used in everyday computing to control the pointer in GUIs. Benefits of a mouse Simple and easy to use Efficient way to navigate Drawbacks of a mouse Requires a flat surface Requires space to operate
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Joystick
A joystick is an input device that can be used for controlling the movement of the cursor or a pointer in a computer device. The pointer/cursor movement is controlled by maneuvering a lever on the joystick. The input device is mostly used for gaming applications and, sometimes, in graphics applications. A joystick also can be helpful as an input device for people with movement disabilities.
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Scanner
A scanner is an input device that scans documents such as photographs and pages of text. When a document is scanned, it is converted into a digital format. This creates an electronic version of the document that can be viewed and edited on a computer.
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Light Pen
Light pen is a pointing device similar to a pen. It is used to select a displayed menu item or draw pictures on the monitor screen. It consists of a photocell and an optical system placed in a small tube. When the tip of a light pen is moved over the monitor screen and the pen button is pressed, its photocell sensing element detects the screen location and sends the corresponding signal to the CPU.
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Track Ball Track ball is an input device that is mostly used in notebook or laptop computer, instead of a mouse. This is a ball which is half inserted and by moving fingers on the ball, the pointer can be moved. Since the whole device is not moved, a track ball requires less space than a mouse. A track ball comes in various shapes like a ball, a button, or a square.
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Digitizer
Digitizer is an input device which converts analog information into digital form. Digitizer can convert a signal from the television or camera into a series of numbers that could be stored in a computer. They can be used by the computer to create a picture of whatever the camera had been pointed at. Digitizer is also known as Tablet or Graphics Tablet as it converts graphics and pictorial data into binary inputs. A graphic tablet as digitizer is used for fine works of drawing and image manipulation applications.
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Microphone
Microphone is an input device to input sound that is then stored in a digital form. The microphone is used for various applications such as adding sound to a multimedia presentation or for mixing music.
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Magnetic Ink Card Reader (MICR)
MICR input device is generally used in banks as there are large number of cheques to be processed every day. The bank's code number and cheque number are printed on the cheques with a special type of ink that contains particles of magnetic material that are machine readable. This reading process is called Magnetic Ink Character Recognition (MICR). The main advantages of MICR is that it is fast and less error prone.
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Optical Character Reader (OCR)
OCR is an input device used to read a printed text. OCR scans the text optically, character by character, converts them into a machine readable code, and stores the text on the system memory.
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Bar Code Readers
Bar Code Reader is a device used for reading bar coded data (data in the form of light and dark lines). Bar coded data is generally used in labelling goods, numbering the books, etc. It may be a handheld scanner or may be embedded in a stationary scanner. Bar Code Reader scans a bar code image, converts it into an alphanumeric value, which is then fed to the computer that the bar code reader is connected to.
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Optical Mark Reader (OMR)
OMR is a special type of optical scanner used to recognize the type of mark made by pen or pencil. It is used where one out of a few alternatives is to be selected and marked. It is specially used for checking the answer sheets of examinations having multiple choice questions.
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Computer - Output Devices
An output device is any piece of computer hardware equipment which converts information into human-readable form. It can be text, graphics, tactile, audio, and video.
Some of the important output devices used in a computer. Monitors Graphic Plotter Printer
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Monitors
Monitors, commonly called as Visual Display Unit (VDU), are the main output device of a computer. It forms images from tiny dots, called pixels that are arranged in a rectangular form. The sharpness of the image depends upon the number of pixels. There are two kinds of viewing screen used for monitors. Cathode-Ray Tube (CRT) Flat-Panel Display
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Cathode-Ray Tube (CRT) Monitor
The CRT display is made up of small picture elements called pixels. The smaller the pixels, the better the image clarity or resolution. It takes more than one illuminated pixel to form a whole character, such as the letter ‘e’ in the word help.
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Cathode-Ray Tube (CRT) Monitor
A finite number of characters can be displayed on a screen at once. The screen can be divided into a series of character boxes - fixed location on the screen where a standard character can be placed. Most screens are capable of displaying 80 characters of data horizontally and 25 lines vertically. There are some disadvantages of CRT − Large in Size High power consumption
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Flat-Panel Display Monitor
The flat-panel display refers to a class of video devices that have reduced volume, weight and power requirement in comparison to the CRT. You can hang them on walls or wear them on your wrists. Current uses of flat-panel displays include calculators, video games, monitors, laptop computer, and graphics display.
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Flat-Panel Display Monitor
The flat-panel display is divided into two categories − Emissive Displays − Emissive displays are devices that convert electrical energy into light. For example, plasma panel and LED (Light-Emitting Diodes). Non-Emissive Displays − Non-emissive displays use optical effects to convert sunlight or light from some other source into graphics patterns. For example, LCD (Liquid-Crystal Device).
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Printers
Printer is an output device, which is used to print information on paper. There are two types of printers − Impact Printers Non-Impact Printers
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Impact Printers
Impact printers print the characters by striking them on the ribbon, which is then pressed on the paper. Characteristics of Impact Printers are the following − Very low consumable costs Very noisy Useful for bulk printing due to low cost There is physical contact with the paper to produce an image These printers are of two types − Character printers Line printers
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Character Printers Character printers are the printers which print one character at a time. These are further divided into two types: Dot Matrix Printer(DMP) Daisy Wheel
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Dot Matrix Printer In the market, one of the most popular printers is Dot Matrix Printer. These printers are popular because of their ease of printing and economical price. Each character printed is in the form of pattern of dots and head consists of a Matrix of Pins of size (5*7, 7*9, 9*7 or 9*9) which come out to form a character which is why it is called Dot Matrix Printer.
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Dot Matrix Printer Advantages Inexpensive Widely Used Other language characters can be printed
Disadvantages Slow Speed Poor Quality
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Daisy Wheel Head is lying on a wheel and pins corresponding to characters are like petals of Daisy (flower) which is why it is called Daisy Wheel Printer. These printers are generally used for word-processing in offices that require a few letters to be sent here and there with very nice quality.
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Daisy Wheel Advantages More reliable than DMP Better quality Fonts of character can be easily changed
Disadvantages Slower than DMP Noisy More expensive than DMP
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Line Printers Line printers are the printers which print one line at a time. These are of two types − Drum Printer Chain Printer
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Drum Printer This printer is like a drum in shape hence it is called drum printer. The surface of the drum is divided into a number of tracks. Total tracks are equal to the size of the paper, i.e. for a paper width of 132 characters, drum will have 132 tracks. A character set is embossed on the track. Different character sets available in the market are 48 character set, 64 and 96 characters set. One rotation of drum prints one line. Drum printers are fast in speed and can print 300 to 2000 lines per minute.
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Drum Printer Advantages Very high speed
Disadvantages Very expensive Characters fonts cannot be changed
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Chain Printer In this printer, a chain of character sets is used, hence it is called Chain Printer. A standard character set may have 48, 64, or 96 characters.
Advantages Character fonts can easily be changed. Different languages can be used with the same printer. Disadvantages Noisy
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Non-impact Printers
Non-impact printers print the characters without using the ribbon. These printers print a complete page at a time, thus they are also called as Page Printers. These printers are of two types − Laser Printers Inkjet Printers
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Non-impact Printers
Characteristics of Non-impact Printers Faster than impact printers They are not noisy High quality Supports many fonts and different character size
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Laser Printers These are non-impact page printers. They use laser lights to produce the dots needed to form the characters to be printed on a page. Advantages Very high speed Very high quality output Good graphics quality Supports many fonts and different character size Disadvantages Expensive Cannot be used to produce multiple copies of a document in a single printing
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Inkjet Printers Inkjet printers are non-impact character printers based on a relatively new technology. They print characters by spraying small drops of ink onto paper. Inkjet printers produce high quality output with presentable features. They make less noise because no hammering is done and these have many styles of printing modes available. Color printing is also possible. Some models of Inkjet printers can produce multiple copies of printing also.
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Inkjet Printers Advantages High quality printing More reliable Disadvantages Expensive as the cost per page is high Slow as compared to laser printer
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Plotters
A plotter is basically a large printer that is used to print vector graphics and continuous lines. A traditional printer cannot draw continuous lines, it makes lines out of dots. Plotters can print larger graphics than a printer can.
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Plotter Applications
Plotters are mostly used for CAD (Computer-aided design) and CAE (Computer-aided engineering). A plotter prints more precisely than a traditional printer does and was one of the first types of printers that could print in color and render full-size engineering drawings. Therefore, plotters are typically used for more technical types of drawings such as mechanical drawings, building plans, circuit diagrams, charts, and more. Plotters are mostly used for computer-aided design but are slowly being phased out by wide format printers.
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Types of Plotters
The different types of plotters include: Drum plotters Flatbed plotters Electrostatic plotter Roller Plotter
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Drum plotters A drum plotter draws on paper that is wrapped around a drum. The drum turns and produces one direction of the plot, while at the same time the pens move to produce the other direction.
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Flatbed plotters A flatbed plotter draws on paper that is placed on a flat surface.
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Electrostatic plotter An electrostatic plotter draws on paper that has a negative charge with a toner that has a positive charge.
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Roller Plotter A roller plotter prints out the drawing while the payer gets moved through the plotter.
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Memory The CPU needs to have millions (or even trillions, in some computers) of bytes of space where it can quickly read or write programs and data while they are being used. This area is called memory. There are two types of built-in memory: permanent and nonpermanent.
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Permanent and Non-permanent Memory Permanent memory is nonvolatile. Most of the memory in a microcomputer—lose their contents when the computer’s power is shut off. This type of non-permanent memory is called volatile.
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Storage Evaluation Criteria
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Main Memory Every computer has a temporary storage built into the computer hardware. It stores instructions and data of a program mainly when the program is being executed by the CPU. This temporary storage is known as main memory, primary storage, or simply memory. Physically, it consists of some chips either on the motherboard or on a small circuit board attached to the motherboard of a computer. It has random access property. It is volatile.
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Main Memory Organization
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Main Memory Organization Machines having smaller word-length are slower in operation than machines having larger word-length. A write to a memory location is destructive to its previous contents. A read from a memory location is non-destructive to its previous contents.
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Fixed Word--length Memory Storage space is always allocated in multiples of word- length. Faster in speed of calculation than variable word-length memory. Normally used in large scientific computers for gaining speed of calculation.
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Variable Word--length Memory
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Memory Capacity Memory capacity of a computer is equal to the number of bytes that can be stored in its primary storage. Its units are: Kilobytes (KB) : 1024 (210) bytes Megabytes (MB) : 1,048,576 (220) bytes Gigabytes (GB) : 1,073,741824 (230) bytes
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Random Access Memory (RAM) Primary storage of a computer is often referred to as RAM because of its random access capability. RAM chips are volatile memory. A computer’s motherboard is designed in a manner that the memory capacity can be enhanced by adding more memory chips. The additional RAM chips, which plug into special sockets on the motherboard, are known as single-in- line memory modules (SIMMs).
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Read Only Memory (ROM) ROM a non-volatile memory chip. Data stored in a ROM can only be read and used – they cannot be changed. ROMs are mainly used to store programs and data, which do not change and are frequently used. For example, system boot program.
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Flash Memory Flash memory is a special type of nonvolatile memory. It is often used in portable digital devices for storage. Digital cameras, portable MP3 players, USB “ keychain“ storage devices, and game consoles all use flash memory.
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Optical Disk
An optical disk is any computer disk that uses optical storage techniques and technology to read and write data. It is a computer storage disk that stores data digitally and uses laser beams (transmitted from a laser head mounted on an optical disk drive) to read and write data.
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Optical Disk
Compact disks (CD), digital versatile/video disks (DVD) and Blu-ray disks are currently the most commonly used forms of optical disks. These disks are generally used to: Distribute software to customers Store large amounts of data such as music, images and videos Transfer data to different computers or devices Back up data from a local machine
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Data Representation Bit Byte Binary Decimal Hexadecimal Octal Systems Conversions Binary Arithmetic (Addition/ Subtraction/ Multiplication) Applications of IT
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Bit A bit (short for "binary digit") is the smallest unit of measurement used to quantify computer data. It contains a single binary value of 0 or 1. A binary number consisting of n bits is called an n-bit number.
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Byte Bits are often grouped together in 8-bit clusters called bytes. Since a byte contains eight bits that each have two possible values, a single byte may have 28 or 256 different values.
Generally, files, storage devices, and storage capacity are measured in bytes, while data transfer rates are measured in bits.
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Number Systems Two types of number systems are: Non-positional number systems Positional number systems
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Non--positional Number Systems Characteristics Use symbols such as I for 1, II for 2, III for 3, IIII for 4, IIIII for 5, etc Each symbol represents the same value regardless of its position in the number. The symbols are simply added to find out the value of a particular number. Difficulty It is difficult to perform arithmetic with such a number system.
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Positional Number Systems Characteristics Use only a few symbols called digits. These symbols represent different values depending on the position they occupy in the number.
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Positional Number Systems The value of each digit is determined by: 1. The digit itself 2. The position of the digit in the number 3. The base of the number system
(base = total number of digits in the number system) The maximum value of a single digit is always equal to one less than the value of the base.
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Decimal Number System Characteristics A positional number system. Has 10 symbols or digits (0, 1, 2, 3, 4, 5, 6, 7, 8, 9). Hence, its base = 10. The maximum value of a single digit is 9 (one less than the value of the base). Each position of a digit represents a specific power of the base (10). We use this number system in our day-to-day life.
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Decimal Number System Example 3 2 1 0 258610 = (2 x 10 ) + (5 x 10 ) + (8 x 10 ) + (6 x 10 ) = 2000 + 500 + 80 + 6
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Binary Number System Characteristics A positional number system. Has only 2 symbols or digits (0 and 1). Hence its base = 2. The maximum value of a single digit is 1 (one less than the value of the base). Each position of a digit represents a specific power of the base (2). This number system is used in computers.
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Binary Number System Example 4 3 2 1 101012 = (1 x 2 ) + (0 x 2 ) + (1 x 2 ) + (0 x 2 ) x (1 x 20) = 16 + 0 + 4 + 0 + 1
= 2110
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Fractional Numbers Fractional numbers are formed same way as decimal number system. In general, a number in a number system with base b would be written as:
an an-1… a0 . a-1 a-2 … a-m And would be interpreted to mean: n n-1 0 -1 -2 an x b + an-1 x b + … + a0 x b + a-1 x b + a-2 x b + -m … + a-m x b The symbols an , an-1, …, a-m in above representation should be one of the b symbols allowed in the number system.
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Formation of Fractional Numbers in Binary Number System (Example)
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Formation of Fractional Numbers in Binary Number System (Example)
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Formation of Fractional Numbers in Octal Number System (Example)
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Formation of Fractional Numbers in Octal Number System (Example)
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Binary Arithmetic Binary arithmetic is essential part of all the digital computers and many other digital system.
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Binary Addition It is a key for binary subtraction, multiplication, division. There are four rules of binary addition.
In fourth case, a binary addition is creating a sum of (1 + 1 = 10) i.e. 0 is written in the given column and a carry of 1 over to the next column.
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Binary Addition Example
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Binary Subtraction Subtraction and borrow these two words will be used very frequently for the binary subtraction. There are four rules of binary subtraction.
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Binary Subtraction Example
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Binary Multiplication Binary multiplication is simpler than decimal multiplication because only 0’s and 1’s are involved. There are four rules of binary multiplication.
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Binary Multiplication Example
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Information Technology (IT)
The term Information Technology (IT) was coined by Jim Domsic of Michigan in November 1981. Information Technology is a general term that describes any technology that helps to produce, manipulate, store, communicate and/or disseminate information. The use of computers and information are associated. “Information Technology” as defined by the Information Technology Association of America (ITAA), is "the study, design, development, implementation, support or management of computer-based information systems, particularly software applications and computer hardware." IT deals with the use of computers and computer software to convert, store, protect, process, transmit and securely retrieve information. Dr. Kajal Rai
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Applications of IT Science and Engineering: Scientific progress in fields like biotechnology is almost entirely dependent on the use of computers and other microprocessor-controlled devices. Using supercomputers, meteorologists predict future weather by using a combination of observations of weather conditions from many sources, a mathematical representation of the behavior of the atmosphere, and geographic data. Computer-aided design (CAD) and computer-aided manufacturing (CAM) programs have led to improved products in many fields, especially where designs tend to be very detailed. Computer programs make it possible for engineers to analyze designs of complex structures such as power plants and space stations.
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Applications of IT Business & Commerce: One of the first and largest applications of computers is keeping and managing business and financial records. Most large companies keep the employment records of all their workers in large databases that are managed by computer programs. Similar programs and databases are used in business functions like billing customers; tracking payments received and payments to be made; and tracking supplies needed and items produced, stored, shipped, and sold. In fact, practically all the information companies need to do business involves the use of computers and Information Technology. Almost all the financial transactions in the world are done electronically. Newer technologies like m-commerce have enabled almost everybody to carry out routine financial transactions on the move.
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Applications of IT Education: The advent of Information Technology has changed the meaning of the term “literate”, with computer literacy being almost as important as basic literacy in many cases. Computer education is an essential course at the primary level in most schools across the world. With more information getting digitized every day, and the internet making it accessible to anyone across the world, students are increasingly relying on electronic sources of information rather than physical libraries for their needs. Instructional methodology has also undergone a sea change with use of images, animations, videos, presentations and e-learning to complement traditional techniques.
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Applications of IT Governance: The concept of e-governance is one of the most novel applications of Information Technology whereby it is changing the lives of millions across the globe. Computerization of Government activities makes it easier to supervise and audit, and makes the administration more responsive to the needs of society. It also bridges the divide between the Government and the people. Technologies like touch-screen kiosks help disseminate information on land records, photo identity cards, pending bills etc. and enable even illiterate people to take more informed decisions. India is leading the world in the effective use of IT for elections.
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Applications of IT Medicine: Information Technology plays an important role in medicine. For example, a scanner takes a series of pictures of the body by means of computerized axial tomography (CAT) or magnetic resonance imaging (MRI). A computer then combines the pictures to produce detailed three-dimensional images of the body's organs. In addition, the MRI produces images that show changes in body chemistry and blood flow. Most critical life support equipment are programmed to respond to changes in the patient’s status in split-seconds, thereby reducing the response time and risk of human error. Newer concepts like robotic surgery enable specialists to perform surgeries from remote locations. Genomic studies greatly depend on supercomputing power to develop technologies for the future.
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Applications of IT Entertainment: IT has changed the lifestyle of most people. The convergence of various technologies has created various options for entertainment like games, streaming music and video, digital television broadcasts, satellite radio, animated movies etc. which can be accessed with the help of mobile phones, PDAs, notebook computers or on television either with a cable connection or wirelessly using newer-generation WiFi, CDMA or GPRS technologies.
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Applications of IT Information Technology plays a vital role in most of our daily activities. There is hardly anyone who has not been affected or influenced by IT. With each passing day, newer applications of IT are being developed which increase our interaction with and dependence on IT-enabled devices. Therefore, understanding this technology and using it creatively is imperative to human progress.
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