The main functioning of a computer system is based on the combined usage of both input and output devices. Utilizing an input device, a user can give directions to the computer to run and the device reverts to the user’s action through an output device. Let’s understand first what is an input unit and output unit.
This part of the computer encapsulates devices with the help of which the user feeds data to the computer. It creates an interface between the user and the computer. The input devices transform the information into a form acceptable by the computer.
This part of the computer encapsulates devices with the help of which the user receives the information from the computer. Output devices transform the output from the computer into a form understandable by the users.
Through this article Input and Output Devices, we shall review the various input and output devices which can be attached to a computer, along with their functions.
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Input Devices of Computer
A piece of hardware/equipment that enables the user to enter data into a computer is called an input device. Some of the Commonly used input units used in a computer system are as follows:
- Light pen
- Track Ball
- Graphic Tablet
- Magnetic Ink Card Reader (MICR)
- Optical Character Reader (OCR)
- Barcode Reader
- Optical Mark Reader (OMR)
The keyboard is the most basic and very commonly used input device which helps to input data to the computer. The layout of the buttons in a normally used keyboard is similar to the traditional typewriter, but there are a few additional keys provided by different manufacturers for performing additional functions.
Normally available keyboards in the market were of two sizes 84 keys and 101/102 keys, but now keyboards with 104 keys or 108 keys are also possible for Windows and Internet.
Following is the description of the buttons on the keyboard:
These buttons include the letter keys (A-Z) and digit keys (09) which normally give the same arrangement as typewriters.
These buttons are used to input the numeric data or cursor movement. Normally, it consists of a set of 17 keys that are placed out in a similar configuration practiced by most additional machines and calculators.
The 12 function keys are provided on the keyboard which is arranged in a row at the top of the keyboard. Each of these keys has a different function and is applied for some specific task.
These buttons are used for cursor and screen control. It also adds four directional arrow keys. Following are also included in control keys: Home, End, Delete, Insert, Page Up, Page Down, Control (Ctrl), Escape (Esc)Alternate (Alt).
Special Purpose Keys
A regular keyboard also contains some special purpose buttons like Enter, Caps Lock, Shift, Num Lock, Space bar, Print Screen, and Tab.
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It is the most commonly used pointing device. It is a very famous cursor-control device and the earlier versions of it were built over a small palm-size box with a round ball at its base, which tracks the movement of the mouse and feeds digital signals to the CPU when the mouse buttons are pressed. Currently, the mouse has a sensor at the bottom to detect cursor position.
Basic versions if it has two buttons called the left and the right-click button and a wheel is present between the buttons to provide a scroll function. The movement of the mouse on a flat surface is used to control the position of the cursor on the display, but it cannot be used to feed text into the system directly.
- Easy to use
- Not very expensive
- The cursor movement is faster than the arrow keys of the keyboard.
Just like a mouse, a Joystick is also a pointing device, which is used to travel the cursor position on a display. It is a perpendicular stick having a spherical ball at both lower and upper ends. The spherical ball connected at the circuit having sensors moves in a socket. The joystick controller can be traversed in all directions.
The functionality of the joystick is just like a mouse. Its applications are generally in Computer-Aided Designing (CAD) and playing computer games.
Just like a pen, a light pen is a digital pointing device. This device is used to select an item displayed in the menu or to draw anything on the display. It contains a photocell and an optical sensor placed in a small tube at the tip.
When the light pen tip is traveled on the display, its photocell sensing element calculates the screen location and sends the digital signal to the CPU.
The trackball is another type of input device similar to the mouse. It is most helpful with a notebook or laptop computer, instead of a mouse. It consists of a ball on the top which is half inserted and connected to the sensors. By moving fingers on the ball, the cursor can be moved.
Because the whole device is not moved to move the cursor, a trackball requires less space as compared to the mouse. This device comes in different shapes like a ball, a square, or a button.
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A scanner is another input device, which works very much like a photocopy machine. It can be used when some information on paper is to be transferred to the hard disk of the computer in digital format for further manipulation.
The scanner captures high-resolution images from the source which are then converted into a digital format that can be saved on the disk and shared digitally. These digital images can be edited before they are printed.
A digitizer is also an input device that is used to convert analog information into digital form. Using a digitizer, the signal from the television or camera can be transformed into a series of numbers that could be saved in a computer hard drive. They can be helpful with the computer to create a picture of whatever the camera has been pointed at.
Digitizer is also called Tablet or Graphics Tablet because it transforms graphics and pictorial data into binary inputs to the system. A special kind of graphic tablet as a digitizer is used for fine works of drawing and image-related applications.
A microphone or mic is a very common input device used to input sound that is then stored in a digital form. Nowadays microphones are used in almost every industry and devices related to sound recording or transmission.
The microphone is used for different applications like adding sound to a multimedia presentation or for mixing music, voice calling and recording, video conferencing, and more.
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Magnetic Ink Card Reader (MICR)
The MICR input device is commonly seen in banks as there are a huge amount of cheques to be processed every day. The important details like the bank’s code number and cheque number are printed on the cheques with specially designed ink based on the particles of magnetic material that is readable by the sensors of the machine.
This method of reading is recognized as Magnetic Ink Character Recognition (MICR). The main benefits of using MICR are that it is comparatively fast and less prone to errors.
Optical Character Reader (OCR)
It is an input device that is used to read a printed text similar to the scanner, but the method of reading and the type of output generated is different. The format to be fed to the OCR is predefined and can’t be used as an ordinary scanner.
OCR, unlike a scanner, scans the text optically, character by character, converts them into a machine-readable digital code instead of creating high-resolution images, and stores the text on the system memory.
Bar Code Readers
Bar Code Reader is an input device used to read special format barcoded data (data in the form of light and dark lines). Barcoded data is commonly used to create price tags, in labeling goods, numbering the books, etc. It can be a handheld scanner or can be embedded in a stationary scanner on the tabletop.
A flash of light from the device strikes the surface of the object and reflects the sensors present behind the source of light to collect the input. Bar Code Reader can only scan a bar code image, converts it into an alphanumeric value, which is then transferred to the computer that the bar code reader is connected to.
Optical Mark Readers (OMR)
OMR is a special type of input machine. This sort of optical scanner is used to identify the type of mark made by pen or pencil. It is used where one out of a predefined alternative is to be selected and marked.
The format to be fed to the OMR is predefined and can’t be used as an ordinary scanner.
It is specially used for automation of the answer sheet analysis of examinations having multiple-choice questions.
A Webcam is a camera that is combined with a computer. Unlike a digital camera, they cannot function independently and should be connected to the computer/laptop for operation. It functions as an input device that can take pictures and is mostly used for video streaming and video conferencing or chatting.
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Biometrics relates to a method in which a person is identified through his/her biological features such as fingerprints, facial structure, eye cornea, etc. It is done by using biometric devices, which can be of different types based on their scanning features and abilities, such as Face Scanner, Hand Scanner, Fingerprint Scanner, Retina or Iris Scanner, Voice Scanner, etc.
A piece of hardware/equipment that presents the result of the entered input, once it is processed, is called an output device. Several output devices display output in various ways such as images, text, hard copies, and audio/video. Following are some of the commonly used output devices used in a computer system:
Monitors or Visual Display Unit (VDU), are the primary output devices of a computer system. It generates images from tiny dots, termed pixels that are arranged in a well-defined rectangular form. The depth and sharpness of the image depend upon the number and size of the pixels.
There are two types of digital screens used for monitors:
- Cathode-Ray Tube (CRT)
- Flat-Panel Display
Cathode-Ray Tube (CRT)
The Cathode-Ray Tube display consists of small picture elements known as pixels. The tinier the pixels, the greater the image clarity or resolution. It requires a very large number of pixels emitting light to create a character.
A limited number of characters can be arranged on a screen at a time. The screen can be categorized into a series of character boxes – a fixed place on the screen where a standard character can be shown. The capability of earlier screens was to display 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 is a class of video output devices that have decreased volume, weight, and power requirement as compared to the CRT. It is possible to hang them on walls or wear them on wrists. In everyday evolving technology, uses of flat-panel displays include laptops or computers, calculators, monitors, video games, and graphics displays.
The flat-panel display is categorized into the following two categories:
- Emissive Displays − Emissive displays panels are output devices that transform electrical energy into light. For instance, plasma panels and LED (Light-Emitting Diodes).
- Non-Emissive Displays − Non-emissive displays are based on optical effects to convert sunlight/light from some other source into graphics patterns. For example, LCD (Liquid-Crystal Device).
A printer is a very commonly practiced output device, which is used to print information on paper. There are two types of printers:
- Impact Printers
- Non-Impact Printers
Impact printers print by hitting the characters on the ribbon containing ink, which is then pressed on the paper.
Following are the characteristics of Impact Printers:
- Very low consumable prices.
- Pretty noisy.
- Helpful for bulk printing due to economic costs.
These printers are of two types:
- Character printers
- Line printers
Character printers are the type of printers that are capable of printing only one character at a time. This states that it does not print one line at a time.
Character printers can be categorized into two types:
- Dot Matrix Printer (DMP)
- Daisy Wheel
Dot Matrix Printers
In the earlier days, one of the most commonly practiced printers was the Dot Matrix Printer. These printers were used commonly because of their ease of usage, printing, and affordable printing price. Every character to be printed on paper is created by rearranging a matrix of metallic pins of size (5×7, 7×9, 9×7, or 9×9) at a very fast speed which comes out to create a character which is why it is known as the Dot Matrix Printer.
- Extensively Used.
- Other language letters can be printed.
- Slow Speed.
- Too much heat generation takes place.
- Poor Quality.
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IN this type of printer the Head is fixed on a wheel and pins creating characters are like petals of Daisy (flower) that is why it is identified as Daisy Wheel Printer. These printers are generally used for word-processing tasks in offices that demand a very low number of letters to be sent here and there with very nice quality.
- More reliable than the Dot Matrix Printer.
- Quality is better.
- Fonts of character can be effortlessly changed.
- Slower than a Dot Matrix Printer.
- More expensive than the Dot Matrix Printer.
These types of printers are capable of printing one line at a time.
These are two types of line printers.
- Drum Printer
- Chain Printer
The head of this printer is in the form of a drum, which is why it is identified as a drum printer. The printing drum surface is divided into several tracks which are equivalent to the size of the paper. For instance, if a paper is of the width of 200 characters, then the drum will have 200 tracks. A fixed character set is embossed on the track which cannot be altered by any means.
To use a different character set, a different drum needs to be purchased like the one with the 48 character set, or the 64 and 96 characters set. A single rotation of the drum containing permanent characters prints a single line. These printers offer fast printing speed and can print 300 to 2000 lines per minute.
- Tremendous speed
- Character fonts cannot be modified.
In this type of printer, a chain consisting of the character set is used, that is why it is identified as a Chain Printer, or in other words a Chain printer is a line printer that applies a rotating chain to print characters. The predefined-standard character set can have 48, 64, or 96 characters.
- It is simple to change character fonts.
- Different languages can be managed by replacing chains with the same printer.
- These types of printers are Noisy.
Non-impact printers do not hit the paper with any embossed character-containing instrument. These printers can print a complete page all at once, this is the reason why they are also known as Page Printers.
These printers are of two types:
- Laser Printers
- Inkjet Printers
Characteristics of Non-impact Printers
These types of printers are faster than impact printers.
- Not noisy
- High quality
- Supports multiple fonts and various character sizes.
These are very commonly used these days and are a type of non-impact page printer. They use laser lights to charge the metallic drum in the shape of characters or objects to be printed, which attracts powdered ink. Then this drum is pressed over the page to create printed output.
Inkjet printers are also very commonly used printers these days. They use ink cartridges to print characters by spraying small drops of ink in a very precise manner onto the paper. Inkjet printers are very versatile and can produce relatively high-quality output with presentable features.
They make very little noise as compared to other printers because no hammering is done and these have many different modes of printing. Using these printers, color printing is also possible. Some advanced and newer models of Inkjet printers are capable enough to produce multiple number copies of printing also.
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A projector is an optical output device that can take images produced by a computer and project or present them onto a screen or surface called a projector. In the older version of projectors, images were created by shining the light through a small transparent lens on the projector; however, the new version of projectors uses laser technology for the same. Projectors are most commonly used in offices, classrooms, auditoriums, theatres to watch presentations, videos, or pictures generated from a computer or laptop.
Computer speakers are the most popular output devices used with a computer to listen to sound. These speakers receive audio as input either in analog or digital form and generate sound as an output. With the advancement of technology, speakers are now available with wireless and BlueTooth facilities as well.
The headphones or earphones or headsets are hardware output tools that are either plugged into the computer or can be wireless. They offer the same function as a speaker, the only difference is the frequency of sound. With speakers, the sound can be detected over a larger distance while utilizing headphones, the sound is only audible to the individual using them. Headphones are available in multiple shapes and sizes.
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Input and Output Devices FAQs
Typing Keys, Numeric Keypad, Function Keys, Control keys, and Special Purpose Keys are available on the keyboard.
Simply one can understand Input is data that a computer takes, on the other hand, the output is data that a computer transfers. Computers only work with digital information.
OCR stands for Optical Character Reader and OMR stands for Optical Mark Readers.