Computer Peripherals

Computer hardware refers to the physical parts or components of a computer such as monitor, keyboard, computer data storage, hard drive disk, mouse, system unit (graphic cards, sound cards, memory, mother board and chips), etc. all of which you can actually touch. Computer hardware is the physical components (devices), which are the building blocks of personal computers. These are installed into a computer case, or attached to it by a cable or through a port. In the latter case, they are also referred to as peripherals. A combination of hardware and software forms a usable computing system.

Input / Output (I/O) Devices:

These devices are used to enter information and instructions into a computer for storage or processing and to deliver the processed data to a user. I/O devices are required for users to communicate with the computer. In simple terms, input devices bring information INTO the computer and output devices bring information OUT of a computer system. These I/O devices are also known as peripherals since they surround the CPU and memory of a computer system. Computer Peripherals divides in to the following categories based on their usage:

Input Devices:

An input device is any device that provides input to a computer. There are many input

devices, but the two most common ones are a keyboard and mouse. Every key you press on the keyboard and every movement or click you make with the mouse sends a specific input signal to the computer.

Examples: Keyboard, Mouse, Image Scanner, Digital Camera, Webcam, Joy stick, Trackball, Touchpad, Touch Screen, Light Pen, Bar code reader, Microphone, Graphics tablet, Magnetic ink character recognition (MICR), Optical mark recognition (OMR), etc.


  1. Keyboard:

The keyboard is very much like a standard typewriter keyboard with a few additional keys. The basic QWERTY layout of characters is maintained to make it easy to use the system.

  • The additional keys are included to perform certain special functions.
  • These are known as function keys that vary in number from keyboard to keyboard.


Note: Number of organisations are manufacturing Key Boards for PCs, among which Sony, Samsung, Zebronics, Amkette are famous.

  1. Mouse:

A device that controls the movement of the cursor or pointer on a display screen.

  • A mouse is a small object you can roll along a hard and flat surface.
  • Its name is derived from its shape, which looks a bit like a mouse.
  • As you move the mouse, the pointer on the display screen moves in the same direction.


  1. Scanner:

A scanner is a device that captures images from photographic prints, posters, magazine pages, and similar sources for computer editing and display.

  • Scanners come in hand-held, feed-in, and flatbed types and for scanning black-and-white only, or color.
  • Very high resolution scanners are used for scanning for high-resolution printing, but lower resolution scanners are adequate for capturing images for computer display.
  • Scanners usually come with software, such as Adobe’s Photoshop product, that lets you resize and otherwise modify a captured image.


  1. Digital Camera

A digital camera records and stores photographic images in digital form. Many current models are also able to capture sound or video, in addition to still images.

  • Capture is usually accomplished by use of a photosensor , using a charged coupled device (CCD).
  • These stored images can be uploaded to a computer immediately or stored in the camera for to be uploaded into a computer or printer later.
  • Images may also be archived on a photographic compact disc or external hard disk.


  1. Web Camera

A webcam – short for ‘web camera’ – is a digital camera that’s connected to a computer. It can send live pictures from wherever it’s sited to another location by means of the internet.

  • Many desktop computer screens and laptops come with a built-in camera and microphone, but if yours doesn’t, you can add a separate webcam at any time.
  • There are various types. Some are plugged into computers through USB ports, but others are wireless (wifi).

Other features might include:

  • An integral microphone
  • The ability to pan and tilt
  • In-built sensors that can detect movement and start recording
  • A light that, when on, will let you know that the camera is in use.


  1. Joy Sticks

In computers, a joystick is a cursor control device used in computer games and assistive technology .

  • The joystick, which got its name from the control stick used by a pilot to control the ailerons and elevators of an airplane, is a hand-held lever that pivots on one end and transmits its coordinates to a computer.
  • It often has one or more push-buttons, called switches, whose position can also be read by the computer.


  1. Trackball

A trackball is a computer cursor control device used in many notebook and laptop computers.

  • The trackball is usually located in front of the keyboard toward the user.
  • Essentially, the trackball is an upside-down mouse that rotates in place within a socket.
  • The user rolls the ball to direct the cursor to the desired place on the screen and can click one of two buttons (identical to mouse buttons) near the trackball to select desktop objects or position the cursor for text entry.


  1. TouchPad

A touch pad is a device for pointing (controlling input positioning) on a computer display screen.

  • It is an alternative to the mouse. Originally incorporated in laptop computers, touch pads are also being made for use with desktop computers.
  • A touch pad works by sensing the user’s finger movement and downward pressure.
  • The first touch pad was invented by George E. Gerpheide in 1988. Apple Computer was the first to license and use the touch pad in its Powerbook laptops in 1994.


  1. Touch Screen

A touch screen is a computer display screen that is also an input device. The screens are sensitive to pressure; a user interacts with the computer by touching pictures or words on the screen.

There are three types of touch screen technology:

Resistive: A resistive touch screen panel is coated with a thin metallic electrically conductive and resistive layer that causes a change in the electrical current which is registered as a touch event and sent to the controller for processing.

  • Resistive touch screen panels are generally more affordable but offer only 75% clarity and the layer can be damaged by sharp objects.
  • Resistive touch screen panels are not affected by outside elements such as dust or water.


Surface wave: Surface wave technology uses ultrasonic waves that pass over the touch screen panel. When the panel is touched, a portion of the wave is absorbed.

  • This change in the ultrasonic waves registers the position of the touch event and sends this information to the controller for processing.
  • Surface wave touch screen panels are the most advanced of the three types, but they can be damaged by outside elements.


Capacitive: A capacitive touch screen panel is coated with a material that stores electrical charges.

  • When the panel is touched, a small amount of charge is drawn to the point of contact.
  • Circuits located at each corner of the panel measure the charge and send the information to the controller for processing.
  • Capacitive touch screen panels must be touched with a finger unlike resistive and surface wave panels that can use fingers and stylus.
  • Capacitive touch screens are not affected by outside elements and have high clarity.


  1. Light Pen:

Light pen is an input device that utilizes a light-sensitive detector to select objects on a display screen.

  1. Bar code reader:  

Bar-code readers are photoelectric scanners that read the bar codes or vertical zebra stripes marks, printed on product containers.

  • These devices are generally used in super


markets, bookshops etc.

Example for Bar code reader figure shown here. (A handheld canon barcode scanner). Note: Number of organisations are manufacturing Barcode Scanners, among which Zebronics, Creative are some.

  1. Micro Phone:

Micro Phone is also used as input device to store Sound/noise into the computer.

  • All of the different noises we hear are caused by minute pressure differences in the air around us.
  • A microphone transducer or sensor that converts sound into an electrical signal and helps to stored into the Computers.
  • An AKG Perception 120 USB condenser microphone.


  1. Graphics Tablets:

A Graphics Tablet or Digitizer is a computer input device that enables a user to hand-draw images, animations and graphics, similar to the way a person draws images with a pencil and paper.

  • These tablets may also be used to capture data or handwritten signatures. It can also be used to trace an image from a piece of paper which is taped or otherwise secured to the surface.
  • Capturing data in this way, either by tracing or entering the corners of linear poly-lines or shapes is called digitizing.


  1. Magnetic ink character recognition (MICR) :

Magnetic ink character recognition (MICR) is an input device functions on character recognition technology used mainly by the banking industry to ease the processing and clearance of cheques and other documents.

  • The MICR encoding called the MICR line, is at the bottom of cheques and other vouchers and typically includes the document-type indicator, bank code, bank account number, cheque number, cheque amount, and a control indicator.
  • This device particularly finds applications in banking industry.


  1. Optical Mark Recognition (OMR):

Optical Mark Recognition, also called mark sense reader is a technology where an OMR device senses the presence or absence of a mark, such as pencil mark. OMR is widely used in tests such as aptitude test.


Output Devices:

Output devices bring information OUT of a computer system. These output devices are also known as peripherals since they surround the CPU and memory of a computer system.

Examples: Monitor, printer, projector, plotter, Speaker (loudspeaker).

  1. Monitor:

A monitor or a display is an electronic visual display unit for computers.

  • The display device in modern monitors is typically a thin film transistor liquid crystal display (TFT-LCD) thin panel, while older monitors use a cathode ray tube (CRT) about as deep as the screen size. In computers, a monitor is a computer display and related parts packaged in a physical unit that is separate from other parts of the computer.


Note: Number of organisations are manufacturing Monitor’s for PC among which

Sony, Samsung, LG, HP, HCL are famous

  1. Printer:

In computers, a printer is a device that accepts text and graphic as output from a computer and transfers the information to paper, usually to standard size sheets of paper. Printers vary in size, speed, sophistication, and cost.

  • In general,  more expensive printers are used for higher-resolution color printing. Printers can also be categorized based on the print method or print technology.
  • The most popular ones are dot-matrix printer, laser printer, inkjet printer and Multi Function Printers (MFP) / All-in-One Printers. Among these, only dot-matrix printer is impact printer and the others are non-impact printers.


Dot‐matrix printer: Dot‐matrix printer is an impact printer that produces text and graphics when tiny wire pins on the print head strike the ink ribbon.

  • The print head runs back and forth on the paper like a typewriter. When the ink ribbon presses on the paper, it creates dots that form text and images. Higher number of pins means that the printer prints more dots per character, thus resulting in higher print quality.
  • Dot‐matrix printers were very popular and the most common type of printer for personal computer in 70’s to 80’s. However, their use was gradually replaced by inkjet printers in 90’s. As of today, dot matrix printers are only used in some point‐of‐sales terminals, or businesses where printing of carbon copy multi‐part forms or data logging are needed.


Laser printer: Laser Printers are non‐impact printers which can print text and images in high speed and high quality resolution, ranging from 600 to 1200 dpi.

  • Laser printer use toner (black or colored powder) instead of liquid inks. A laser printer consists of these major components: drum cartridge, rotating mirror, toner cartridge and roller.
  • The drum cartridge rotates as the paper is fed through. As the drum rotates and presses on paper, toner is transferred from the drum to paper, creating images. Rollers then use heat and pressure to fuse toner to paper. Colored laser printers add colored toner.


Inkjet Printer: Inkjet printers are non-impact printers which print text and images by spraying tiny droplets of liquid ink onto paper.

  • They are the most popular printers for home use. Currently, most inkjet printers use either thermal inkjet or piezoelectric inkjet technology.
  • Thermal inkjet printer uses heating element to heat liquid ink to form vapor bubble, which forces the ink droplets onto the paper through the nozzle. Most inkjet manufacturers use this technology in consumer inkjet printers.


Multi Function / All‐in‐One Printers (MFP): It is also known as all‐in‐one printer or multifunction device (MFD). It is a machine that includes several functionalities including printer, scanner, copier and fax.

  • Multifunction printer is very popular in So Ho (small office / home office) offices.
  • It can use either inkjet or laser print method. Some multifunction printers also have media card readers, allowing printing of pictures directly from digital cameras without using a computer.
  • In the following figure we shown model of Samsung SCX-6320F Multi-functional Laser Printer.


Note: Number of organisations are manufacturing different types of printers and Samsung, Epson, HP. Xerox, TVS, Wipro are some of the well-known famous manufacturers among them.

  1. Projector or Video Projector:

Video Projector is an image projector that receives a video signal and projects the corresponding image on a projection screen using a lens system.

All video projectors use a very bright light to project the image, a video projector, also known as a digital projector, may project onto a traditional reflective projection screen, or it may be built into a cabinet with a translucent rear-projection screen to form a single unified display device.


  1. Plotter:

A device that draws pictures on paper based on commands from a computer.

  • Plotters differ from printers in that they draw lines using a pen. As a result, they can produce continuous lines, whereas printers can only simulate lines by printing a closely spaced series of dots.
  • Multicolor plotters use different colored pens to draw different colors. In general, plotters are considerably more expensive than printers.


  1. Speaker:

A loudspeaker is an electro acoustic transducer that produces sound in response to an electrical audio signal input. the term “loudspeaker” may refer to individual transducers (known as “drivers”) or to complete speaker systems consisting of an enclosure including one or more drivers.

  • To adequately reproduce a wide range of frequencies, most loudspeaker systems employ more than one driver, particularly for higher sound pressure level or maximum accuracy.
  • Individual drivers are used to reproduce different frequency ranges. The drivers are named subwoofers (for very low frequencies); woofers (low frequencies); midrange speakers (middle frequencies); tweeters (high frequencies).



Here some of the devices like Floppy disk drive, hard disk drive, optical disc drive, Flash Drive (Discussed in earlier) are used as both I / O devices.


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