Download Chapter 5: Input and Output

Computers:
Tools for an Information Age
Chapter 5
Input and Output: The User Connection
Objectives
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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
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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
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Users submit data (input) to the computer to
get processed information (output)
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Output can be instant reaction to input
Also can be separated by time, distance, or both
Instant Reaction
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Items scanned at supermarket
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Forklift operator speaks to computer
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Forklift obeys operator’s commands
Sales rep enters an order on a pad
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Produce item name and price at counter
Characters displayed as “typed” text and stored in pad
Factory workers punch a time clock as they go from
task to task
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Produce weekly paychecks and management reports
Input and Output Separated
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Data on checks input into bank computer
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Charge-card transactions provide input
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Computer processes entries once a month to
prepare statements
Processed monthly to produce customer bills
Water samples collected and input into
computer
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Used to produce reports that show patterns of
water quality
Input: Getting Data from the User to the
Computer
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Keyboard
Pointing devices
Source data automation
Keyboard
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Similar to typewriter keyboard
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Can be unique to an industry
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May be part of a personal computer
May be part of a terminal connected to a
computer in another location
Keys on McDonald’s keyboards represent Big
Mac or large fries
Ergonomic keyboards
Ergonomic Keyboards
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Designed to reduce or
minimize repetitive
strain injury of wrists
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Provide more natural,
comfortable position of
wrists, arms, and hands
Pointing Devices
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Used to position a pointer on the screen
Communicate commands to operating
system by clicking a button
Common devices
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Mouse
Devices used for games
Devices used in laptops
Others
The First Mouse
Invented by Doug Englebart at SRI, 1963/4
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.
Mouse
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The most common pointing device
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Movement on flat surface causes movement
of pointer on screen
Several types
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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
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Trackball
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Variation on mechanical mouse
User rolls the ball directly
Often built into laptop computers
Joystick
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Short lever with handgrip
Distance and speed of movement
controls pointer’s position
Pressing trigger causes actions to take
place
Touchpad and Pointing Stick
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Touchpad
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Rectangular pressure-sensitive pad
Sliding finger across pad moves pointer
Tapping with finger recognized as click
Pointing stick
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Small pressure-sensitive post mounted in
center of keyboard
Pushing post in any direction moves pointer
Other Pointing Devices
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Graphics tablet
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Touch screen
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User moves stylus or puck across board
Used to create or trace precise drawings
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
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Use pen-like stylus to input data
Often used in PDAs or pocket PCs
Source Data Automation
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Use of special equipment to collect data at
the source
Primary areas
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Magnetic-ink character recognition (MICR)
Optical recognition devices
Other sources
MICR
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Uses a machine to read
characters made of
magnetized particles
Banking industry is
predominant user
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Characters preprinted on
lower left-hand side of check
Amount added by MICR
inscriber when check is
cashed
Optical Recognition
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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
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Scanners at supermarkets
Document imaging - converts
paper documents to electronic
versions
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Documents stored on disk
Can be edited or processed by
software
Scanners
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Flatbed scanner
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Sheetfed scanner
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Motorized rollers feed sheet across
scanner head
Handheld scanner
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Typically scans one page at a time
Can be used to scan large bound
documents
Smallest and least accurate
Optical character recognition (OCR)
software required to convert picture into
characters
Other Optical Recognition Methods
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Optical Mark Recognition
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Optical character recognition
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Machine senses marks on piece of
paper
Wand reader reads characters in
special typeface
Bar Codes
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A series of vertical marks
Represents a unique code
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Universal Product Code (UPC) used
as standard in supermarkets
Other Sources
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Voice input
Digital cameras
Video input
Voice Input
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User speaks to computer
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Most are speaker-dependent
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Speech recognition devices
convert spoken words into
binary digits
System “learns” user’s voice
Types of systems
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Discrete word systems - user
must pause between words
Continuous word systems - user
can speak normally
Digital Camera
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User takes photo that is stored on
a chip
Photo can be downloaded to
computer
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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
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Digital video consists of
series of still frames
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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
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Computer screens
Printers
Voice output
Music output
Microform
Computer Screen Technology
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Screen is part of computer’s monitor
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Screen output known as soft copy
Intangible and temporary
Common forms
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Cathode ray tube (CRT)
Flat-panel screens
Smart displays
CRT Screens
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Display text and graphics
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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
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Scan rate
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Resolution (clarity) of screen
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Measured in pixels (picture elements)
The more pixels, the higher the resolution
Graphics standards
Dot pitch
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The frequency with which the image is refreshed
The amount of space between dots
The smaller the dot pitch, the sharper the image
Video memory
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A high-speed form of RAM installed on graphics card
Graphic Standards
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Agree on resolutions, colors, other issues
related to displaying graphics
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Super Video Graphics Adapter (SVGA) is most
common standard
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Provides 800 (horizontal) x 600 (vertical) pixels on the
display
Other varieties of SVGA exist
Support 16 million colors
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The number of colors that can be displayed depends
on amount of video memory
Flat-Panel Screens
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Liquid crystal display (LCD)
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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
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Active-matrix
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Passive-matrix
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Uses many thin-film transistors (TFT)
Produces brighter image and can be viewed from wider
angles
Uses fewer transistors
Cheaper and uses less power
Gas plasma
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Supports very large displays
Has brilliant color display
Viewable at very wide angles
Smart Displays
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Based on flat-panel technology
Each contains its own processor
Wireless transmitter-receiver allows user to
control desktop from anywhere in the house
Printers
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Produce information on paper output
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Orientation settings
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Printed output known as hard copy
Portrait - vertical alignment
Landscape - horizontal alignment
Two ways of printing
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Impact printer
Non-impact printer
Impact Printers
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Physical contact with paper required
to produce image
Line printer
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Prints an entire line of a program at
once
Typically used with mainframe
computers printing lengthy reports
Dot-matrix printer
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Has print head consisting of one or
more columns of pins
Pins form characters and images as
pattern of dots
Non-impact Printers
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Places an image on a page without
physically touching the page
Laser printer
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Uses light beam to help transfer images
to paper
Produces high-quality output at very fast
speeds
Ink-jet printer
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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
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Voice synthesizers convert data to vocalized sounds
Two approaches
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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
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Useful when an inquiry would be followed by a short reply,
such as a balance inquiry
Music Output
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Multimedia clips, games, videos include sight and
sound
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Speakers placed on side of monitor
Powered sub-woofers produce low-frequency sounds
Musical Instrument Digital Interface (MIDI)
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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)
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Output of photographically reduced
images on microfilm or microfiche
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Microfilm - images stored on continuous
roll of film
Microfiche - images stored in rows and
columns on a card
Needs special reader
Common uses
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Libraries store back issues of periodicals
Businesses store large volumes of
historical records
Terminals
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Combine input and output capabilities
Dumb terminal
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Intelligent terminal
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Keyboard for input and monitor for output
No processing capability
Has limited memory and a processor
Point-of-sale (POS) terminal
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Captures retail sales data when transaction takes
place
Computer Graphics
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Business graphics
Video graphics
Computer-aided design/computer-aided
manufacturing (CAD/CAM)
Business Graphics
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A powerful way to impart
information
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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
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A series of video images
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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
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Creates two- and threedimensional designs
Performs engineering tests
such as stress tests
Serves as bridge between
design and manufacturing
Ethics and Data
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Once data is in computer, there are many
ways it can be used
Ethical issues to ponder
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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?