Computers: Tools for an Information Age Chapter 5 Input and Output: The User Connection.

Computers:Tools for an Information Age

Chapter 5

Input and Output: The User Connection

Objectives

Describe the user relationship with computer input and output

Explain how data is input into a computer system and differentiate among various input equipment

Describe how a monitor works and the characteristics that determine quality

List and describe the different methods of computer output

Objectives

Differentiate among different kinds of printers Explain the function of a computer terminal

and describe the types of terminals Describe the ethical considerations involved

in handling computer data

How Users See Input and Output Users submit data (input) to the computer to

get processed information (output) Output can be instant reaction to input Also can be separated by time, distance, or both

Instant Reaction

Items scanned at supermarket Produce item name and price at counter

Forklift operator speaks to computer Forklift obeys operator’s commands

Sales rep enters an order on a pad Characters displayed as “typed” text and stored in pad

Factory workers punch a time clock as they go from task to task Produce weekly paychecks and management reports

Input and Output Separated

Data on checks input into bank computer Computer processes entries once a month to

prepare statements Charge-card transactions provide input

Processed monthly to produce customer bills Water samples collected and input into

computer Used to produce reports that show patterns of

water quality

Input: Getting Data from the User to the Computer Keyboard Pointing devices Source data automation

Keyboard

Similar to typewriter keyboard May be part of a personal computer May be part of a terminal connected to a

computer in another location Can be unique to an industry

Keys on McDonald’s keyboards represent Big Mac or large fries

Ergonomic keyboards

Ergonomic Keyboards

Designed to reduce or minimize repetitive strain injury of wrists Provide more natural,

comfortable position of wrists, arms, and hands

Pointing Devices

Used to position a pointer on the screen Communicate commands to operating

system by clicking a button Common devices

Mouse Devices used for games Devices used in laptops Others

The First Mouse

Doug Engelbart invented the computer mouse in 1963-64 as part of an experiment to find better ways to point and click on a display screen. It was made in a shop at SRI. The casing was carved out of wood. The mouse had only one button - that was all there was room for.

Invented by Doug Englebart at SRI, 1963/4

Mouse

The most common pointing device Movement on flat surface causes movement

of pointer on screen Several types

Mechanical - small ball on underside rolls as mouse is moved

Optical - uses a light beam to monitor mouse movement

Cordless - uses either infrared or radio waves, rather than a cord, to connect to computer

Trackball and Joystick

Trackball Variation on mechanical mouse User rolls the ball directly Often built into laptop computers

Joystick Short lever with handgrip Distance and speed of movement

controls pointer’s position Pressing trigger causes actions to take

place

Touchpad and Pointing Stick

Touchpad Rectangular pressure-sensitive pad Sliding finger across pad moves pointer Tapping with finger recognized as click

Pointing stick Small pressure-sensitive post mounted in

center of keyboard Pushing post in any direction moves pointer

Other Pointing Devices

Graphics tablet User moves stylus or puck across board Used to create or trace precise drawings

Touch screen Allow user to touch items on screen Position of finger on screen determines

item to be input into system Used at kiosks in public places such as

malls Pen-based computing

Use pen-like stylus to input data Often used in PDAs or pocket PCs

Source Data Automation

Use of special equipment to collect data at the source

Primary areas Magnetic-ink character recognition (MICR) Optical recognition devices Other sources

MICR

Uses a machine to read characters made of magnetized particles

Banking industry is predominant user Characters preprinted on

lower left-hand side of check Amount added by MICR

inscriber when check is cashed

Optical Recognition

Uses a light beam to scan data and convert to electrical signals

Common uses Scanners are the most common form Other optical recognition methods

Common Uses

Scanners at supermarkets Document imaging - converts

paper documents to electronic versions Documents stored on disk Can be edited or processed by

software

Scanners

Flatbed scanner Typically scans one page at a time Can be used to scan large bound

documents Sheetfed scanner

Motorized rollers feed sheet across scanner head

Handheld scanner Smallest and least accurate

Optical character recognition (OCR) software required to convert picture into characters

Other Optical Recognition Methods Optical Mark Recognition

Machine senses marks on piece of paper

Optical character recognition Wand reader reads characters in

special typeface Bar Codes

A series of vertical marks Represents a unique code

Universal Product Code (UPC) used as standard in supermarkets

Other Sources

Voice input Digital cameras Video input

Voice Input

User speaks to computer Speech recognition devices

convert spoken words into binary digits

Most are speaker-dependent System “learns” user’s voice

Types of systems Discrete word systems - user

must pause between words Continuous word systems - user

can speak normally

Digital Camera

User takes photo that is stored on a chip

Photo can be downloaded to computer

Use photo-editing software to enhance

Store permanently on CDs or DVDs

Photos composed of many pixels of color

Photos stored on removable memory card

Video Input

Digital video consists of series of still frames

Displayed rapidly enough to give illusion of motion

Web cam used to transmit video over the Internet

Can capture video from analog sources with video capture card

Output: Information for the User Computer screens Printers Voice output Music output Microform

Computer Screen Technology

Screen is part of computer’s monitor Screen output known as soft copy Intangible and temporary

Common forms Cathode ray tube (CRT) Flat-panel screens Smart displays

CRT Screens

Display text and graphics Most are in color Some monochrome monitors are

used in applications that have no need for color or graphics

Graphics card converts signals from the control unit into the image the user sees

Factors Affecting Performance Scan rate

The frequency with which the image is refreshed Resolution (clarity) of screen

Measured in pixels (picture elements) The more pixels, the higher the resolution Graphics standards

Dot pitch The amount of space between dots The smaller the dot pitch, the sharper the image

Video memory A high-speed form of RAM installed on graphics card

Graphic Standards

Agree on resolutions, colors, other issues related to displaying graphics Super Video Graphics Adapter (SVGA) is most

common standard Provides 800 (horizontal) x 600 (vertical) pixels on the

display Other varieties of SVGA exist Support 16 million colors

The number of colors that can be displayed depends on amount of video memory

Flat-Panel Screens

Liquid crystal display (LCD) Originally used for laptops, but

making their way to desktop computers

Very thin (only a few inches) Produce sharper text images

than CRTs Easier on eyes than CRTs Different flat-panel technologies

LCD Technologies

Active-matrix Uses many thin-film transistors (TFT) Produces brighter image and can be viewed from wider

angles Passive-matrix

Uses fewer transistors Cheaper and uses less power

Gas plasma Supports very large displays Has brilliant color display Viewable at very wide angles

Smart Displays

Based on flat-panel technology Each contains its own processor Wireless transmitter-receiver allows user to

control desktop from anywhere in the house

Printers

Produce information on paper output Printed output known as hard copy

Orientation settings Portrait - vertical alignment Landscape - horizontal alignment

Two ways of printing Impact printer Non-impact printer

Impact Printers

Physical contact with paper required to produce image

Line printer Prints an entire line of a program at

once Typically used with mainframe

computers printing lengthy reports Dot-matrix printer

Has print head consisting of one or more columns of pins

Pins form characters and images as pattern of dots

Non-impact Printers

Places an image on a page without physically touching the page

Laser printer Uses light beam to help transfer images

to paper Produces high-quality output at very fast

speeds Ink-jet printer

Sprays dots of ink from jet nozzles Can print in both black and white and

color Requires high-quality paper so ink does

not smear Less expensive than laser printers

Voice Output

Voice synthesizers convert data to vocalized sounds Two approaches

Synthesis by analysis - analyzes actual human voice, records and plays back as needed

Synthesis by rule - uses linguistic rules to create artificial speech

Used in automated telephone-based customer service applications Useful when an inquiry would be followed by a short reply,

such as a balance inquiry

Music Output

Multimedia clips, games, videos include sight and sound Speakers placed on side of monitor Powered sub-woofers produce low-frequency sounds

Musical Instrument Digital Interface (MIDI) Rules for connecting musical instruments, synthesizers,

and computers Allows users to set up home studios that rival capabilities

of professional recording studios

Computer Output Microform (COM) Output of photographically reduced

images on microfilm or microfiche Microfilm - images stored on continuous

roll of film Microfiche - images stored in rows and

columns on a card Needs special reader Common uses

Libraries store back issues of periodicals Businesses store large volumes of

historical records

Terminals

Combine input and output capabilities Dumb terminal

Keyboard for input and monitor for output No processing capability

Intelligent terminal Has limited memory and a processor

Point-of-sale (POS) terminal Captures retail sales data when transaction takes

place

Computer Graphics

Business graphics Video graphics Computer-aided design/computer-aided

manufacturing (CAD/CAM)

Business Graphics

A powerful way to impart information Colorful graphics, maps, and

charts help managers compare data, spot trends, and make quicker decisions

As underlying data changes, charts and graphs are instantly updated

Video Graphics

A series of video images Displayed rapidly to give the impression of motion

Used extensively in television Also used in computer and arcade video

games

Computer-Aided Design/Computer-Aided Manufacturing Creates two- and three-

dimensional designs Performs engineering tests

such as stress tests Serves as bridge between

design and manufacturing

Ethics and Data

Once data is in computer, there are many ways it can be used

Ethical issues to ponder Is it ethical to use a computer to alter

photographs? Is it ethical to erase e-mail messages that may be

of interest to a party in a lawsuit? Is it ethical to use someone else’s data for your

purposes?