Commonly used Computer Input Devices

You can now enter data and commands directly and easily into a computer system through pointing devices like electronic mice and touch pads, and technologies like political scanning, handwriting conviction, and voice recognition. These developments have made it unnecessary to always record data on paper source documents (such as sales order forms, for example) and then keyboard the data into a computer in an additional data entry step. Further improvements in voice recognition and other technologies should enable an even more natural user interface in the future.

Pointing Devices:

Keyboards are still the most widely used devices for entering data and text into computer systems. However, pointing devices are a better alternative for issuing commands, making choices, and responding to prompts displays on your video screen. They work with you operating systems graphical user interface (GUI), which presents you with icons, menus, windows, buttons, bars, and so on, for your selection. For example, pointing devices such as electronic mice and touch pads allow you to easily choose from menu selections and icon displays using point-and-click or point-and-drag methods.

The electronic mouse is the most popular pointing device used to move the cursor on the screen, as well as to issue commands and make icon and menu selections. By moving the mouse on a desktop or pad, you can move the cursor onto and icon displayed on the screen. Pressing buttons on the mouse activates various activities representation by the icon selected.

The trackball, pointing stick, and touch pad are other pointing devices most often used in place of the mouse. A trackball is a stationary device related to the mouse. You turn a roller ball with only its top exposed outside its case to move the cursor on the screen. A pointing stick (also called a track point ) is a small button like device, sometimes likened to the eraser head of pencil. It is usually centered one row above the space bar of a keyboard. The cursor moves in the direction of the pressure you place on the stick. The touch pad is a small rectangular touch-sensitive surface usually placed below the keyboard. The cursor moves in the direction your finger moves on the pad. Trackballs, pointing sticks, and touch pads are easier to use than a mouse for portable computer users and are thus built into most notebook computer keyboards.

Touch screens are devices that allow you to use a computer by touching the surface of its video display screen. Some touch screens emit a grid of infrared beams, sound waves, or a slight electric current that is broken when the screen is touched. The computer senses the point in the grid where the break occurs and responds with an appropriate action. For example, you can indicate your selection on a menu display by just touching the screen next to that menu item.

Pen-Based Computing:

Pen-based computing technologies are being used in many hand-held computers and personal digital assistants. These small PCs and PDA’s contain fast processors and software that recognizes and digitizes handwriting, hand printing, and hand drawing. They have a pressure sensitive layer like a graphics pad under their slate like  liquid crystal display (LCD) screen. So instead of writing on paper form fastened to a clipboard or using a keyboard device, you can use a pen to make selections, send E-Mail, and enter handwritten data directly into a computer.

A variety of other pen like devices are available. One example is the digitizer pen and graphics tablet. You can use the digitizer pen as a [pointing device, or use it to draw or write on the pressure-sensitive surface of the graphics table. Your handwriting or drawing is digitized by the computer, accepted as input, displayed on its video screen, and entered into your application.

Voice Recognition and Response:

Voice recognition promises to be the easiest method for data entry, word processing, and conversational computing, since speech is the easiest, most natural means of human communication. Voice input has now become technologically and economically feasible for a variety of applications. Early voice recognition products used discrete speech recognition, where you had to pause each spoken word. New continuous speech recognition (CSR) software recognizes continuous, conversationally paced speech.

Voice recognition systems analyze and classify speech or vocal tract patterns and convert them into digital codes for entry into a computer system. Typically, voice recognition systems with large vocabularies require training the computer to recognize your voice in order to achieve a high degree of accuracy. Training such system involves repeating a variety of words and phrases in a training session and using the system extensively. Trained systems regularly achieve a 95 to 99 percent word recognition rate.

Two example of continuous speech recognition software for word processing are Naturally Speaking by Dragon Systems and Via Voice by IBM. Minimum requirements are a 133 MHz Pentium class microprocessor,32 MB  of RAM, an industry standard sound card, and 50 MB  of available hard disk capacity. The products have 30,000-word vocabularies expandable to 60,000 words, and sell for less than $200.Training to 95 percent accuracy takes only a few hours. Longer use, faster processors, and more memory make 99 percent accuracy possible.

Speaker-independent voice recognition systems, which allow a computer to under stand a few words from a voice it has never heard before, are being built into products and used in a growing number of applications. Examples include voice-messaging computers, which use voice recognition and voice response software to verbally guide an end user through the steps of a task in many kinds of activities. Typically, they enable of applications include computerized telephone call switching, telemarketing surveys, bank pay-by-phone bill-paying services, stock quotations services, university registration systems, and customer credit and account balance inquiries.

Voice recognition devices in work situations allow operators to perform data entry without using their hands to key in data or instructions and to provide faster and more accurate input. For example, manufacturers use voice recognition systems for the inspection, inventory, and quality control of a variety of products; and airlines and parcel delivery companies use them for voice-directed sorting of baggage and parcels. Voice recognition can also help you operate your computer’s operating systems and software packages through voice input of data and commands. In addition, some internet browsers can be voice-enabled so you can send E-mail and surf the World Wide Web via voice recognition.

Optical Scanning:

Optical scanning devices read text or graphics and convent them into digital input for your computer. Thus, optical scanning enables the direct entry of data from source documents into a computer system. For example, you can use a com[pact desktop scanner to scan pages of text and graphics into your computer for desktop publishing and Web publishing applications. Or you can scan documents of all kinds into your system and organize them into folders as part of a document management library system for east reference or retrieve.

There are many types of optical scanners, but they all employ photoelectric devices to scan the characters being read. Reflected light patterns of the data are converted into electronic impulses that are then accepted as input into the computer system. Compact desktop scanners have become very popular due to their low cost and ease of use with personnel computer systems. However, larger, more expensive flatbed scanners are faster and provide higher resolution color scanning.

The credit card billing operations of credit card companies, banks, and oil companies use a form of optical scanning called optical character recognition (OCR). OCR scanners read the characters and codes on credit card receipts, utility bills, insurance premiums, airline tickets, and other documents. OCR scanners are also used to automatically sort mail, score tests, and process a wide variety of forms in business and government.

Devices such as handheld optical scanning wands are frequently used to read OCR coding on merchandise tags and other media. Many business applications involve reading bar coding, a code that utilizes bars to represent characters. One common example is the Universal Product Code (UPC bas coding that you see on packages of food items and many other products. For example, the automated checkout scanners found in supermarkets read UPC bar coding. Supermarket scanners emit laser beams that are reflected off a UPC bar code. The reflected image is converted to electronic impulses that are sent ot the in-store computer, where they are matched with pricing information. Pricing information is returned to the terminal, visually displayed, and printed on a receipt for the customer.

Other Input Technologies:

Magnetic stripe technology is a familiar form of data entry that helps computers read credit cards. The dark magnetic stripe on the back of such cards is the same iron oxide coating as on magnetic tape. Customer account numbers can be recorded on the mag stripe so it can be read by bank ATMs, credit card authorization terminals, and many other types of magnetic stripe readers.

Smart cards that embed a microprocessor chip and several kilobytes of memory into debit, credit, and other cards are popular in Europe, and becoming available in the United States. One example is Holland, where over 8 million smart debit cards have been issued by Dutch banks. Smart debit cards enable you to store a cash balance on the card and electronically transfer some of it to others to pay for small items and services. The balance on the card can be replenished in ATMs or other terminals.

The smart debit cards used in Holland feature a microprocessor and either 8 or 16 kilobytes of memory, plus the usual 200 byte magnetic stripe. The smart cards are widely used to make payments in parking meters, vending machines, newsstands, pay telephones, and retail stores.

Digital cameras represent another fast growing set of input technologies. Digital still cameras and digital video cameras (digital camcorders) enable you to shoot, store, and download still photos or full motion video with audio into your PC. Then you can use image-editing software to edit and enhance the digitized images and include them in new letters, reports, multimedia presentations, and Web pages.

The computer systems of the banking industry can magnetically read checks and deposit slips using magnetic ink character recognition (MICR) technology. Computers can thus sort and post checks to the proper checking accounts. Such processing is possible because the identification numbers of the bank and the customer’s  account are preprinted on the bottom of the checks with an iron oxide-based ink. The first bank receiving a check after it has been written must en-code the amount of the check in magnetic ink on the check’s lower right-hand corner. The MICR system uses 14 characters (the 10 decimal digits and 4 special symbols) of a standardized design. Equipment known as reader-sorters read a check by first magnetizing the magnetic ink characters and then sensing  the signal induced by each character as it passes a reading head. In this way, data are electronically captured by the bank’s computer system.

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