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EXTERNAL DEVICES
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DEFINITION - WHAT DOES ‘EXTERNAL DEVICE’ MEAN?, The external devices or components are the parts that we can touch, for example the monitor, mouse, keyboard and printer., The external components are used either to get data into or out of the computer system.
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INPUT/ OUTPUT DEVICES, The devices which are used to input the data and the programs in the computer are known as “Input Devices” for example keyboard, mouse etc., Input Device can read data and convert them to a form that a computer can use., Output Device can produce the final product of machine processing into a form usable by humans for example monitor, printer, plotter, speaker etc.
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TYPES OF INPUT DEVICES, Keyboard – , i) One of the primary input devices used to input , data and commands. , ii)It has function keys, control keys, arrow keys, , letters, numbers and commands. , iii)Keyboards are connected to the computer , through USB or Bluetooth.
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FUNCTION KEYS(F1-F12), ESC KEY, DIRECTION KEYS, NUMERIC KEYPAD, BACKSPACE KEYS, CANTROL KEYS, NAVIGATION AND EDITING KEYS, ALT KEYS, WINDOWS KEY
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2)MOUSE, Mouse is the most popular pointing device. It is a very famous cursor-control device, Generally, it has two buttons called the left and the right button and a wheel is present between the buttons. A mouse can be used to control the position of the cursor on the screen, but it cannot be used to enter text into the computer.
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Advantages:-, Easy to use , Not very expensive , Moves the cursor faster than the arrow keys of keyboard
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3)SCANNER, Scanner is an input device which works more like a photocopy machine. , It is used when some information is available on a paper and it is to be transferred to the hard disc of the computer for further manipulation. , Scanner captures images from the source which are then converted into the digital form that can be stored on the disc.
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TYPES OF SCANNER:-, Optical Character Reader(OCR), OCR is an input device used to read a printed text. , OCR scans text optically character by character, converts them into a machine readable code and stores the text on the system memory.
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2.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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3) Magnetic Ink Card Reader(MICR), MICR input device is generally used in banks because of a 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).
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4.Bar Code Readers, Bar Code Reader is a device used for reading bar coded data (data in form of light and dark lines). Bar coded data is generally used in labelling goods, numbering the books etc. It may be a hand held 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 to which bar code reader is connected.
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4)LIGHT PEN, Light pen is a pointing device which is similar to a pen. It is used to select a displayed menu item or draw pictures on the monitor screen. , When the tip of a light pen is moved over the monitor screen and pen button is pressed, its photocell sensing element detects the screen location and sends the corresponding signal to the CPU.
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5) JOYSTICK, Joystick is also a pointing device which is used to move cursor position on a monitor screen. , It is a stick having a spherical ball at its both lower and upper ends. The lower spherical ball moves in a socket. The joystick can be moved in all four directions.
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TYPES OF OUTPUT DEVICES, 1) MONITOR:-, The monitor is the most common output device. , It displays information in a pictorial form or commonly referred to as pixels., It includes a screen, circuitry, and the, box, in which the circuit is enclosed. , The user can view the processed data , on the screen.
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2) PRINTER, A printer is a hardware device that produces a hard copy version of the processed data from the computer., Printers are the most common output device to print text or photos., Some printers can print only in black and white, but today, almost all the printers can print monochrome and color prints.
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Types of printer, DOT MATRIX PRINTER:, It is an impact printer makes contact with the paper., It is usually form the print images by processing an ink against the paper by using pins., Dot matrix printers typically print at speed of 100-600 characters per second.
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Advantages:-, Low printing cost., Long Life., Low maintenance cost., , Disadvantages:-, These printers are noisy and have low resolution., They have low printing speed.
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2. Inkjet Printers, Inkjet printers are printers that produce the hard copy by spraying the ink onto the paper. , Inkjet printers are the most widely used type of printer., Advantages:-, High quality printing., More reliable., Compact size and less noisy, Disadvantages:-, More Expensive., Slow as compare to laser printer., Lifetime of inject prints is limited.
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3. Laser Printers, Laser printers use laser lights to produce dots to form the characters for printing., Advantages:-, Very High speed., High quality output., Give good graphics quality., Disadvantages:-, Expensive., Cannot be used to produce multiple copies of a document in a single printing.
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3) PROJECTOR, A projector is an output device that can take images produced by a computer and project them onto a screen or surface., Projectors are used in classrooms, offices, auditoriums, and also at places of worship, as it enables a group of people to watch videos, presentations, or pictures generated from a single computer.
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4)PLOTTER, A plotter is a computer hardware device much like a printer that is used for printing Vector Graphics., Instead of toner, plotters use a pen, pencil, marker, or another writing tool to draw multiple, continuous lines onto paper rather than a series of dots like a traditional printer. Though once widely used for computer-aided design
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STORAGE DEVICES, A storage device is a kind of hardware, which is also known as storage, storage medium, digital storage, or storage media that has the ability to store information either temporarily or permanently., It can be used either internally or externally to a computer system, server or any comparable computing device to hold information.
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THERE ARE TWO DIFFERENT TYPES OF STORAGE DEVICES:, Primary storage devices, Secondary storage devices, Generally smaller in size, are designed to hold data temporarily and are internal to the computer. , They have the fastest data access speed, and include RAM and cache memory., These usually have large storage capacity, and they store data permanently. , They can be both internal and external to the computer, and they include the hard disk, compact disk drive and USB storage device.
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EXAMPLES OF STORAGE DEVICES, 1) HARD DISK:, The hard disk is the most commonly used permanent memory of the computer system., It is capable to store a large amount of data and can be accessed whenever required., Hard disks are flat circular plates made of aluminium or glass and coated with a magnetic material.
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Hard disks for personal computers can store terabytes (trillions of bytes) of information.
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2) Pen Drive , It is a portable device which allows user to transfer data (text, images, videos etc) to and from computer quickly. , Users can easily read and write the data on the Pen Drive by plugging it into the USB port on the computer., Storage capacity of the pen drive can vary from few megabytes to over 100 GB
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3)COMPACT DISC, The term CD ROM means "Compact Disk Read-Only Memory.“ , "ROM", as its name implies the data on the disk is in the form of "read-only," which means the user can read the data only; they cannot erase or modify it.
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4) DVD:-, DVD Stands for "Digital Versatile Disc." A DVD is a type of optical media used for storing digital data., It is the same size as a CD, but has a larger storage capacity, The medium can store any kind of digital data and was widely used for software and other computer files as well as video programs watched using DVD Players.
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It is an Optical disk capable of storing up to 4.7 GB of data.
