4th Class Computers Science Computer and Its Peripherals

Computer and Its Peripherals

Introduction

Computer peripheral is defined as the device that is connected with the host computer. A computer peripheral only useful when it is able to communicate with external or internal environment. When you work with the computer you input your data and instructions. Through some devices to the computer. These devices are called input devices. Similarly, computer after processing given output through other devices called output devices.

Input/ Output devices are known as peripherals since they surround the CPU and memory of a computer system. Computer can also be defined in terms of functions it can perform. A computer can.

        i.      Accept data

       ii.      Store data

      iii.      Process data as desired data

      iv.      Retrieve the stored data and when required and

       v.      Print the result in desired format.

Some of commonly used input/ output devices are listed in the following table:

Input Devices

Input devices are those devices which are used to take data from the user.

Keyboard

A keyboard is a primary input device that looks like a typewriter and also allows you to enter data or information. It is used to type the letters, digits and commands. It is an essential or standard input device without which the computer will not function. It contains a matrix of switches (one switch per key). It typically has characters engraved or printed on the keys and each press of a key typically corresponds to a single written symbol. When a key is pressed, it sends a digital code to the computer which determines which key has been pressed.

The name "QWERTY" comes from the layout of the key beginning with g and ending in M. The letters are arranged by frequency of use in the English language with used letters allocated to natural resting places of the hands on the keyboards.

Letters (Q, W, E, R, T, Y), Numbers (1, 2, 3, 4, 5), Symbols (!, @, #, $, %), spacebar (inserts a pause or space) and Arrows () function primarily to input data; Backspace can be used to erase one letter behind the text cursor (|). Delete in the context of text will erase one letter in front of the text cursor.

Enter (or Return) m the context of text will create a break in the document and begin a new paragraph.

Mouse

The computer mouse is an important device to give instructions to your computer. The mouse is a small device used to point to a particular place on the screen and select in order to perform one or more actions. It can be used to select menu commands, size windows, start programs etc.

Uses of mouse

• Hover: Point to any button or symbol and wait for a couple of seconds. It will tell you its name.
• Click: to press lightly or tap a button.
• Hold: To press a button and keep it pressed.
• Double click: Quickly press the button twice to open programs or document.
• Click and Hold: Press the button and hold it down now you can move your selection anywhere.

Trackball

Trackball a pointing device, is a mouse lying on its back. To move the pointer, You rotate the ball with your thumb, your fingers or the palm of your hand. There are usually one of three buttons next to the ball, which you use just like mouse buttons.

The advantage of trackballs over mouse is that the trackball is stationary so it does not require much space to use it. In addition, you can place a trackball on any type of surface, including your lap. For both these reasons, trackballs are popular pointing devices for portable computer.

Joystick

Joystick is one of the popular input device, which is used for playing video games.

BCR

BCR stands for Bar Code Reader. It is an electronic device which is used to read printed barcodes. Barcodes represents alphanumeric data which is a combination of vertical lines (bars) that vary in width and length. It is a fast and effective way to input data. A Barcode reader uses a laser beam to read series of thick and thin lines which represent the bar code number.

OMR

OMR stands for Optical Mark Reader. It is the scanning of paper to detect the presence or absence of a mark in a predetermined position. Schools and colleges often use OMR for the evaluation of OMR sheets for competitive exams. OMR sheet is also used in the evaluation of questionnaires, surveys and university exam.

MICR

MICR stands for Magnetic Ink Character Recognition. MICR is a character recognition system that uses special ink and characters. MICR technology is used by banks for faster processing of large volumes of cheques. Numbers and characters found on the bottom of the cheques.

OCR

OCR stands for Optical Character Recognition. OCR is needed when the information should be readable both to humans and to a machine and alternative input cannot be predefined.

Web Cameras

A webcam is a small digital video camera directly or indirectly connected to a computer.

Microphone

Microphone is an input device, which takes voice as input. You can send sound or audio input to the computer through a special input device called microphone. A microphone converts the sound received into the computer's format, which is called digitized sound or digital audio. A microphone can work only if your computer has a special hardware known as sound card. Sound is more often used in multimedia where there is recorded narration, music or sound effects. A microphone is a hardware peripheral that is a popular solution for communication using computer.

Scanner

A scanner is a device that is similar to a photocopier. Just as a photocopier prints the given printed image/page on a paper, a scanner creates an electronic form of the printed image which can then be manipulated, changed and modified according to the requirements. The scanners can convert any image, printed text, handwriting into electronic form by shining light on to the image and sensing the intensity of the reflection at every point. Scanners come in 2 different models - Hand-held Scanner and Flatbed Scanner.

Output Devices

Any peripheral that receive or displays output from a computer.

Monitor

The device which displays computer output. The monitor displays the video and graphic?s information. Monitor's commonly called as Visual Display Unit (VDU) are the main output device of a computer. It forms images from tiny dots called pixels that are arranged in a rectangular form. The clarity or sharpness of the image depends upon the number of pixel.

Monitors are classified into the following types:

• Cathode Ray Tube (CRT)
• Monochrome Monitor
• LCD or Flat Monitor

Printer

Printer is an output device, which is used to print information on paper.

There are two types of printers:

• Impact Printers
• Non-Impact printers

 Impact Printers: The impact printers print the characters by striking them on the ribbon which is then pressed on paper.

Characteristics of impact printers are the following:

• Very low consumable costs.
• Very noisy.
• Useful for bulk printing due to low cost.
• There is a physical contact with the paper to produce an image.

Non-Impact Printers: The Non-impact printers prints the characters without using ribbon. These printers print a complete page at a time so they are also called a page printers.

Characteristics of Non-impact printers the followings:

• Faster than impact printers.
• They are not noisy.
• High quality
• Support many fonts and different character size.

Plotter

The plotter is an output device much like a printer that is used for printing diagrams, layout, specification sheets and banner. The plotter is capable of producing color drawing in a matter of minutes. It is considerably more expensive then printers.

Speaker

Speakers are one of the most common type of output device that are attached to the computer and are similar to the ones that are connected to a stereo. It can be used for various sound meant to alert the user, as well as music and spoken text.