Input and output devices in a computer

 Various input and output devices in a computer

Input or output devices are required for users to communicate with the computer. These input/output devices are connected to the cpu through various ports or with the help of wireless technology.

Input devices

In simple terms, input devices feed data and instructions into the computer.

•Various types of input devices:

Keyboard

Allows the user to input text data consisting of alphabets , numbers and other characters. Detects the key pressed and generates the corresponding ASCII Code which can be recognised by the computer . Wired and wireless keyboards are available.

Mouse

A small handheld device used to position the cursor or to move the pointer on the computer screen by rolling it over a mouse pad or in a flat surface . Different types of mouse are ball, optical and laser mouse . Wireless mouse is also available.

Light pen

A pointing device shaped like a pen. Has the advantage of 'drawing' directly on to the screen. Used by engineers, artists, fashion designers for Computer Aided Designing (CAD) and drawing purposes.

Touch screen

Allows the user to operate /make selections by simply touching on the display screen. It can also be operated using a stylus which gives more precision.

Graphic tablet

Consists of an electronic writing area and a special 'pen' that works with it. Allows artists to create graphical images with actions similar to traditional drawing tools.

Joy stick

Used to playing video games, control training simulators and robots. Has a vertical stick which can move in any direction and a button on top that is used to select the option pointed by the cursor.

Microphone

Accepts sound which is analogue in nature as input and convents it to digital format. The digitised sound can be stored in the computer for later processing or playback.

Scanner

Allows capturing of information, like pictures or text and converting it into a digital format that can be edited using a computer. Quality of the image depends on the resolution of the scanner. Optical Character Recognition (OCR) software is used to recognise the text in an image scanned and convert it into text, which can be edited by a text editor.

Optical Mark Reader (OMR)

Another scanning device that reads predefined positions and records where marks are made on the printed from. Useful for applications in which large numbers of hand filled forms need to be processed quickly with great accuracy, such as objective type tests and questionnaires.

Barcode/ quick response (QR) code reader

A bar code is a set of vertical lines of diferent thicknesses and spacing that represent a number. Barcode readers are used to input dala from such set of barcodes. Hand-held scanners, mobile phones with camera and special software are used as barcode readers. QR (Quick Response) code is similar to barcodes. Barcodes are single dimensional where as QR codes are two dimensional. The two dimensional way of storing data allows QR code to store more data than a standard barcode. This code can store website URLs, plain text, phone numbers, email addresses and any other alphanumeric data. The QR code can be read using a barcode reader or a mobile with a camera and special software.

Magnetic Ink Character Recognition (MICR) Reader

MICR readers are used in banks for faster electronic clearing of cheques. The lower portion of a cheque contains cheque number, branch code, bank code, etc.. printed in a special font using an ink containing iron oxide particles. Iron oxide has magnetic properties. MICR reader can easily recognise these characters by magnetically charging them while scanning. This MICR data along with the image of the cheque is send to the cheque drawer's (the person who issues the cheque) branch to transfer the amount. This reduces errors in data entry and speeds up money transfer. 

Biometric sensor

Identifies unique human physical features with high accuracy. It is an essential component of a biometric system which uses physical features like fingerprints, retina, iris patterns, etc. to identify, verify and authenticate the identity of the user.

Smart card reader

Smart card is a plastic card that stores and transacts data. It may contain a memory or a micro processor. Used in banking, healthcare, telephone calling, electronic cash payments and other applications. These are used to access data in a smart card.

Digital camera

Takes pictures and videos and converts it to the digital format. The images are stored in the memory and can be transferred to computer. Web camera is a compact and less expensive version of a digital camera. It is used in computers for video calling, video chatting, etc. It does not have an internal memory.

Output devices

In simple terms, output devices presents information from a computer system.

•various types of output devices:

Visual Display Unit (VDU)

Display devices include CRT monitors, LCD monitors, TFT monitors, LED monitors, gas plasma monitors, Organic Light Emitting Diode (OLED) monitors, etc.... Information shown on a display device is called soft copy. The Size of a monitor is measured diagonally across the screen, in inches.

LCD projector

An LCD projector is a type of video projector for displaying video, images or computer data on a large screen or other flat surface. A beam of high-intensity light which travels through thousands of shifting pixels in an LCD is focused by a lens on the surface.

Printer

Used to produce hardcopy output. The output printed on paper is known as hardcopy. Classified as Impact or Non-impact printers. Dot-matrix uses impact mechanism. It can print carbon copies with less printing cost. Speed is measured in number of characters printed in a unit of time and is represented as characters per second (cps), lines per minute (lpm) or pages per minute (ppm). These printers are slow and noisy. Inkjet printers are non-impact printers that form the image on the page by spraying tiny droplets of ink from the print head. Inkjet printers are inexpensive, but the cost of ink cartridges makes them costly to operate in the long run. Laser printers are non-impact printers that produce good quality images. Monochrome and color laser printers are available. Color laser printers use multiple color toner cartridges to produce color output and are expensive. Laser printers are faster and their speed is rated in pages per minute (ppm). Thermal printer is a non-impact printer that produces a printed image by selectively heating heat sensitive thermal paper when it passes over the thermal print head. The coating turns black in the areas where it is heated, producing an image. It is popular as a portable printer.

Plotter

A plotter is an output device used to produce hardcopies of graphs and designs on the paper. A plotter is typically used to print lage format graphs or maps such as construction maps, engineering drawings and big posters. Plotters are of two types: Drum plotters and Flatbed plotters. A Drum plotter is also known as Roller plotter. A Flatbed plotter is also known as Table plotter.

3D printer

A 3D printer is an output device used to print 3D objects. It can produce different kinds of objects, in different materials, using the same printer. The 3D printing process turns the object to be printed into thousands of tiny little slices. It then prints it from the bottom to top, slice by slice. Those tiny layers stick together to form a solid object.

Audio output device

The audio output is the ability of the computer to produce sound. Speakers are the output devices that produces sound. It is connected to the computer through audio ports.