Information and Communication Technology

Computer Input Devices

An input device presents data to the processing unit in machine-readable form. Although the keyboard is a common input device for a computer, the system may also support one or more the input devices listed in the illustration on the following page.

Keyboard

The keyboard is very much like that of a standard typewriter with a few additional keys. The basic QWERTY layout of characters is maintained to make it easy for the trained typists to use the system. The additional keys are included to perform certain special functions such as deleting a character or editing a text. These are known as function keys that vary in number from system to system. The function keys help operators to automatically perform many tasks that would be tedious and time consuming on an ordinary typewriter.

Optical Character Reader (OCR)

Optical character readers are input devices that are used to read any printed text. They can interpret handmade marks, handwritten characters, machine printed characters and special symbols and codes.

Optical Character Readers scan the text optically, character by character, convert them into machine readable codes and store the text in the system's storage medium. They can read at a rate of up to 2,400 characters per second. This makes it possible for organisations to reduce the input keying bottlenecks. OCR devices are expensive and are used only when there are large quantities of documents to be keyed in. Other advantages of using OCR are:

· It can be used to reformat printed or typed documents by inputting through the reader and outputting on the systems printer.

• It can be used to consolidate texts from various documents into one document.
• It can serve as a link between the word processing system and the conventional typewriter.

Since OCR eliminates the human element in data entry, it improves data accuracy and timeliness of output. However, if the document is poorly prepared, it may create some difficulties.

Magnetic Ink Character Recogniser (MICR)

It is a device that can identify characters printed with ink that contain particles of magnetic material. MICR is used mainly in the banking industry to read cheques. Since the MICR system can recognise only certain character styles, the characters have to be accurately formed.

Mark Sense Reader (MSR)

This device also known as optical mark reader (OMR) can recognise marks made by a pencil or pen on a specially designed card or form. These cards and forms are pre-printed for special purposes so that a mark in a particular position may represent certain meaning. Such forms are used in processing selection tests, survey questionnaires, and the like, where answers are recorded as dark pencil marks in certain boxes.

Graphics Tablet

Graphics tablet is a computer-based terminal with additional features for creating, storing and printing pictures. We can create an image of a picture by simply moving a stylus on the picture. As the stylus moves the picture is created on the screen for checking. The picture can be stored or printed out on a plotter.

A graphics tablet can be used for tracing existing documents such as drawings, company logos, maps or cartoons for integrating them with reports, or for creating new pictures.

Mouse

Mouse is an input device and is used to position the cursor on the screen. It is a palm-sized box. Its manipulation on a flat surface moves the cursor in the same direction as the movement of the mouse. The box contains a ball underneath which senses the movement and transmits it to the computer over the cord.

Trackball

A trackball is a pointing device that works like an upside-down mouse. It consists of an exposed ball which can be rolled with the help of our thumb to move the cursor around the screen. Trackballs are popular with the notebook computers.

Touch Screen

The monitor screen can be designed to be touch-sensitive so that we can input instructions by merely touching on-screen prompts. Such screens are especially helpful when people are unfamiliar with computers.

Light Pen

A light pen is a handheld, light-sensitive stylus attached to a computer that accepts the stylus position on the monitor as an input. We can move the pen across the screen to make menu selections or draw curves.

Bar Code Reader

Bar code is a special bar chart created on products to represent product number, cost and other details. When a bar code is scanned, the bit patterns represented by the marked bars are translated into meaningful information. Bar codes are extensively used in libraries, departmental stores, post offices, inventory and sales departments and so on.

Sensors

In many scientific applications, data input is done through a sensor. These devices allow direct input of physical data to a computer for analysis. This method provides a timely and accurate data acquisition.

Digital Camera

A digital camera can capture a scene, digitise the image and store the digitised image on a small disk within the camera. The disk can be removed and read by a computer.

Voice Recognition

Voice-recognition devices are available that can be used to provide voice input directly to a computer. The computer recognises the spoken words and converts them to output, either in audio form or in printed form. Since these devices understand a limited vocabulary, they are not widely used at present.