Basic Knowledge in IT

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Done By: - M.M.AZNEE, K.KIRISHI, M.SANDARU and G.CHATHUSEKA.

Class- 9f

Royal college

Information Technology

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Contents Introduction to computers Types of computers Input devices Output devices Storage devices


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Introduction to computers

The computer as we know it is a group of pieces of hardware put together to get a job done faster. To accomplish its various tasks, the computer is made of different parts, each serving a particular purpose in conjunction with other parts.A computer is primarily made of the Central Processing Unit, the monitor, the keyboard, and the mouse. Other pieces of hardware, commonly referred to as peripherals, can enhance or improve your experience with the computer.

A basic computer consists of three major components:

1. CPU (Central Processing Unit) 2. IO (Input/output) 3. Memory

Data comes through Input and the CPU processes the data based on a program which is in Memory. The result is returned to Memory or is presented to the user.


http://en.wikiversity.org/wiki/File:Computer_Organization.jpg

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Types of computersA computer is one of the most brilliant inventions of mankind. We are able to achieve an efficient storage and processing of data; we could rest our brains by employing computer memory capacities for storage of the information. Owing to computers, we have been able to speed up our daily work, carry out critical transactions and achieve accuracy and precision in work output. The computers of the earlier years were of the size of a large room and were required to consume huge amounts of electric power. However, with the advancing technology, computers have shrunk to the size of a small watch.

Computers can be generally classified by size and power as follows, though there is considerable overlap:

Personal computer A small, single-user computer based on a microprocessor.Eg: Desktop, Notebook, Tower model, Laptops, Palmtops.

Supercomputer An extremely fast computer that can perform hundreds of millions of instructions per second.

Mainframe computer A powerful multi-user computer capable of supporting many hundreds or thousands of users simultaneously.

Minicomputer A multi-user computer capable of supporting up to hundreds of users simultaneously.

Workstation A powerful, single-user computer. A workstation is like a personal computer, but it has a more powerful microprocessor and, in general, a higher-quality monitor.


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Input devicesAny hardware devices that send data to the computer are known as Input devices. If there is no any input device, a computer would only be a display device and not allow users to interact with it, much like a TV. Input devices are necessary to convert data into a form which can be understood by computers.

Key boardIt is the most common and widely used input device. They are similar to Electronic type writers. Made up of buttons called ‘keys’. The keys are arranged into sections:

Alphabet keys, Function keys (F1,F2), Numeric keys, Command keys (insert, delete,

home)1. Delete : - It is used to remove characters and other objects.2. Backspace: - It is used to moves the cursor backward one character

space while deleting that character.3. Shift : - It is used to give an alternative meaning to the other

keys. We can type capital letters and others like @, #, $, %, ^, &, <, >, “, etc……..

4. Caps lock: - It is used to write upper case letters [capital letters]5. Tab : - It is used to insert a tab character or moves the cursor

to the next tab stop.6. Enter : - It is used to moves the cursor to the beginning of the

next line.


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Ordinary computer keyboards have their keys arranged in a similar way to those on a typewriter. This way of arranging the keys is called QWERTY.


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MouseIt is also an input device commonly used in computers. It is invented by Douglas Engelbart in 1963. It allows an individual to control a pointer in a graphical user interface (GUI). The main goal of any mouse to translate the motion of your hand into signals that the computer can use

Mouse buttons

1. Left mouse button – it lets you to put the cursor at a certain point and to select an object.

2. Right mouse button – its display a list of menu item from which to choose.3. The wheel – it allows you to scroll up and down the page.

Some types of mouse

Optical Mouse: the mouse that uses light to detect movements. It emits a light and senses its reflections as it is moved. It can be rolled over traditional pads as well as over almost any surface other than glass or mirror.

Wireless Mouse: Does not use a cord to connect to the computer. Instead, uses a receiver to communicate with the computer.

Mechanical mouse: the mouse that uses a rubber ball that makes contact with wheels inside the unit when it is rolled on a pad.

Mouse clicks1. Click – Click the left mouse button once.2. Double click – Click the left mouse button twice.3. Right click – Click the right mouse button once.4. Drag and drop – Click the left mouse button while dragging and drop

wherever you want.


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Joy stickThey input directional data like a mouse. The main use of a joystick is to play computer games by controlling the way that something moves on the screen. Joysticks can be used to control movement from side-to-side, up-and-down and diagonally. A joystick will also always have at least one button on it which can be used to make something happen like making a character in a game jump or fire a gun.

Parts of a joy stick

1. STICK2. BASE3. TRIGGER4. EXTRA BUTTONS5. AUTO FIRE SWITCH6. THROTTLE7. HAT SWITCH 8.SUCTION CUP

Barcode readerAn electronic device for reading printed barcodes. It consists of a scanner, a decoder (either built-in or external), and a cable used to connect the reader with a computer.

Scanner


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A scanner is used to copy pictures or other things and save them as files on the computer. A light moves slowly over the surface of the picture or object to be scanned. The colours of the reflected light are detected and digitized to build up a digital image. It is commonly connected to a computer USB and parallel ports.

Flatbed scanners, also called desktop scanners are the most versatile and commonly used scanners.

Sheet-fed scanners are similar to flatbed scanners except the document is moved and the scan head is immobile. A sheet-fed scanner looks a lot like a small portable printer

Handheld scanners use the same basic technology as a flatbed scanner, but rely on the user to move them instead of a motorized belt. This type of scanner typically does not provide good image quality. However it can be useful for quickly capturing text.

Track ball A trackball is a pointing device. A TRACKBALL is used in the same way as a

mouse but it is useful where desk space is limited. It is like an up sided mouse because the user rotates the ball and the main body part stays still. It has buttons like a standard mouse.

MicrophoneSometimes abbreviated as mic, a microphone is hardware peripheral originally invented by Emile Berliner in 1877


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A.D. Microphone is used to input sound into a computer system. Microphones are often used for voice recognition systems which convert sounds made by a user into commands that the computer can carry out. Systems like this are very useful for people who can’t use ordinary input devices such as the mouse and keyboard.

Digital cameraA digital camera can store many more pictures than an ordinary camera. Pictures taken using a digital camera are stored inside its memory and can be transferred to a computer by connecting the camera to it. A digital camera takes pictures by converting the light passing through the lens at the front into a digital image. The quality of the image is dependent on the resolution or the number of pixels. The more pixels, the better the quality and clarity of the image. Most digital cameras range from 4 – 12 Megapixels.

WebcamA webcam is a video capture device connected to a computer or computer network, often using a USB port or, if connected to a network, Ethernet or Wi-Fi. The most popular use is for video telephony, permitting a computer to act as a videophone or video conferencing station. This can be used in messenger programs such as Windows Live Messenger, Skype and Yahoo messenger services. Other popular uses, which include the recording of video files or

even still-images, are accessible via numerous software programs, applications and devices.

Touch screenA touch screen is computer display screen that is sensitive to human touch, allowing a user to interact with the computer by touching an object on the screen. Touch screens are used with information kiosks, computer-


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based training device and system designed to help individuals who have difficulty manipulating a mouse or key board.

Touch padIt can translate the motion and position of a user's fingers to a relative position on screen. They are a common feature of laptop computers and also used as a substitute for a computer mouse where desk space is scarce. Touch pads vary in size but are rarely made

larger than 40 square centimeters, about 6 square inches. They can also be found on personal digital assistants (PDAs) and some portable media players

Pin padA PIN pad is an electronic device used in a debit or smart card-based transaction to input and encrypt the cardholder's PIN. The PIN pad is required so that the customer card can be accessed (in the case of chip cards) and the PIN can be securely entered and encrypted before it is sent upstream to the transaction manager of the switch or the bank.

Light penA light pen is an input device that utilizes a light-sensitive detector to select a displayed menu options on the screen. It is capable of sensing a position on the screen when its tip touches the screen. It allows the user to point to displayed


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objects, or draw on the screen, in a similar way to a touch screen but with

greater positional accuracy. The advantage of a light pen is that it doesn’t need a special screen or screen coating. It pen can work with any CRT-based display, but not with LCD, screens, projectors and other display devices.

Graphics tabletA graphics tablet consists of a flat surface and a pen, or stylus, which can be used to produce freehand drawings or trace around

shapes. When the special pen touches the surface of the graphics tablet data about its position is sent to the computer. This data is used to produce on the screen an exact copy of what is being drawn on the surface of the graphics tablet.


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Output devices Once the computer has processed all the information from the inputs then it must display or output the information in some way. When we use Output devices that enable us to see or hear the information stored in the computer.

There are many different Output devices but the most commonly used are:

1. Monitors 2. Printers 3. Speakers / Headphones 4. Lights 5. Plotters

Monitors The monitor is one of the most important output devices; it is used to display text and pictures. The monitor is also known as the Visual Display Unit (VDU). Picture on monitor are made out of thousands of color dots called pixels. Higher the pixels will higher the quality. There are two type of monitor,

CRT (Cathode Ray Tube)

LCD (Liquid Crystal Display)

Difference between CRT Monitor and LCD Monitor

CRT Monitor LCD Monitor

• Cheapest • Expensive than CRT • Large • Flatter • bulky size • Less bulky • Noisy • Highly quality display • Heavy • Lighter • Generate a lot of heat • Consumes less electricity


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PrintersIt is used to produce printed output on papers which is also known as the hardcopy. There are 3 types of print qualities,

I. Letter quality. [ high resolution]II. Near letter quality. [ medium resolution ]

III. Low draft quality. [ low resolution ]

Bulky Lighter Heavy Cheap Expensive Expensive Low draft quality Near letter quality Letter quality

Dot Matrix: This printer is the oldest of the three and is not used much now because it doesn’t give as good results as the other two. It uses Carbon ribbon and pins.


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Ink Jets: This printer has become cheaper and is commonly used at home as they are perfect for small quantities of work. The ink jets use ink cartridges that are heated up and droplets are then dropped on to the paper forming a small part of the overall image.

Laser : This printer is more expensive that the others however it is excellent for use in work as it is quiet, quick, can be stocked with a lot of paper and produces high-quality work.

PlotterA plotter produces its output using special pens across the paper to create a drawing. Engineers, architects and designers use plotters to produce their drawings or designs. There are now pen-less plotters. Its Drawings are the same quality as the expert. There are 3 different types of plotters,

I. Flatbed plotter hold the paper still while the pen moveII. Drum plotters- these roll paper over the cylinder

III. Pinch-rollers plotters- these are a mixture of the two types above.

Sound card


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Alternatively referred to as a sound board or an audio card, a sound card is an expansion card or integrated circuit that provides a computer with the ability to produce sound that can be heard by the user either over speakers or headphones.

Video adapter Alternatively referred to as a graphics card, video card, video board, or a video controller, a video adapter is an internal circuit board that allows a display device such as a monitor to display images from the computer. Today's video cards are most commonly connected to the AGP, PCI, or PCIe expansion slot on the motherboard, however, can also be found on-board.

Speakers and headphonesThere is usually a small speaker within the computer however to increase the volume and quality of the sound we plug in external speakers which allow us to hear the music better.

Headphones can be plugged into almost all computers and they enable you to listen to your music without disturbing others.

LEDLight can be connect to computer and respond to the signal which tell them to switch on or off. They


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are used to show that the computer is working correctly. These are known as LED’s (light emitting diodes) and they are useful in presentations and also for situations like when a computer is controlling traffic lights. LED’s last approx.

100,000 hours and they can either be dim or very bright.

ProjectorAn output device that can take the display of a computer screen and project a large version of it onto a flat surface is called projector. Projectors are often used in meetings and presentations so that everyone in the room can view the presentation. Projectors used with computers are small devices that are rarely much larger than a toaster and typically weigh a few pounds. There are 2 types of projectors,

I. DLP projectorII. LCD projector

Storage deviceAny type computer devices that store data are called storage devices.


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Hard diskThe hard disk drive is the main, and usually largest, data storage device in a computer. The operating system, software titles and most other files are stored in the hard disk drive.

Compact diskA compact disk (CD) is a popular form of digital storage media used for computer files, pictures, and music. The plastic platter is read and written to by a laser in a CD drive. It comes in several varieties including CD-ROM, CD-R, and CD-RW. James Russell invented the compact disk in 1965. James Russell


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was granted a total of 22 patents for various elements of his compact disk system. However, the compact disk did not become popular until it was mass manufactured by Philips in 1980.

DVDIt is short form for digital versatile disc or digital video disc, a type of optical disk technology similar to the CD-ROM. A DVD holds a minimum of 4.7GB of data, enough for a full-length movie. DVDs are commonly used as a medium for digital representation of movies and other multimedia presentations that combine sound with graphics.

Pen driveThe pen drive is a portable USB flash memory device that can be used to quickly transfer audio, video, and data files from the hard drive of one computer to another.

Floppy diskFloppy disks are small, removable, media storage devices. They record data onto a thin, circular magnetic film encased in a flat, square plastic jacket. Floppy


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disks are somewhat antiquated, having been replaced by memory sticks and re-writable CD storage devices.

RAMRAM is an abbreviation for Random Access Memory. It usually refers to "temporary" memory, which is when the system is shut down, the memory is lost. This is why the memory is referred to as being "random", as any piece of information can be circulated through the memory regardless of its location and its relation to any other information within the RAM. Additional RAM allows a computer to work with more information at the same time which can have a dramatic effect on total system performance. The first of the many RAMs to come in the market was created in 1951 and was used until the late 1960s and early 1970s.

ROM

Read-Only Memory or ROM is an integrated-circuit memory chip that contains configuration data. ROM is commonly called firmware because its programming is fully fixed into the ROM chip. Data stored can neither be erased nor replaced. This means permanent and secure data storage. However, if a mistake is made in manufacture, a ROM chip becomes unusable. A ROM chip is also non volatile so data stored in it is not lost when power is turned off.


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Done By:-M.M.AZNEE, K.KIRISHI, M.SANDARU

AND G.CHATHUSEKA.

Class – 9F

Royal College
