Transcript Computers Tools for an Information Age

CP102: Information Processing
with Computer Systems
A brief introduction to computers
What is a computer
The application of computers
The classification of computers
Copyright © 2003 by Prentice Hall
What is a Computer?
A computer is a machine/device that can
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Accept input (data)
Process the data to create information
Store data
Output data
Follows a stored set of step-by-step instructions
(program)
Data: raw facts representing people and events
Information: data that is organized, meaningful, and
useful
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Computer System Components
Hardware
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Equipment associated with the system
The Basic Components of a Computer
Software
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Programs, instructions that tell the hardware
what to do
People
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Computer programmer: writes software
User/end-user: purchases and uses software
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Hardware
Four primary components:
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Input devices
Processor
Output devices
Storage devices
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Personal Computer System
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Input: What Goes In
Input: the data put into the computer for
processing
Input devices:
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Keyboard
Pointing device, e.g. mouse
Scanner
Voice input
Digital cameras
Video input
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Keyboard
Most common input device
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Generates electrical signals which
are translated into characters
Standard keyboard
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104 keys
Ergonomic Keyboards
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Designed to reduce or minimize
repetitive strain injury of wrists.
Provide more natural, comfortable
position of wrists, arms, and
hands
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Pointing Devices
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
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Mouse
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
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Trackball and Joystick
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
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Touchpad and Pointing Stick
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
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Other Pointing Devices
Graphics tablet
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User moves stylus or puck across board
Used to create or trace precise drawings
Touch screen
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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
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Scanner
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Reads special letters,
numbers, and symbols
Wand reader, bar code reader
often used in stores
Common Uses
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Scanners at supermarkets
Document imaging - converts
paper documents to electronic
versions
Documents stored on disk
Can be edited or processed
by software
Flatbed scanner
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Typically scans one page at a
time
Can be used to scan large
bound documents
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Scanners (continue)
Sheet-fed scanner
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Motorized rollers feed sheet
across scanner head
Handheld scanner
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Smallest and least accurate
Optical character recognition
(OCR) software required to
convert picture into characters
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Source Data Automation
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
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MICR
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
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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
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Other Optical Recognition Methods
Optical Mark Recognition
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Machine senses marks on piece of
paper
Optical character recognition
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Wand reader reads characters in
special typeface
Bar Codes
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A series of vertical marks
Represents a unique code
Universal Product Code (UPC) used
as standard in supermarkets
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Voice Input
User speaks to computer
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Speech recognition devices
convert spoken words into
binary digits
Most are speaker-dependent
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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
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Digital Camera
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
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Video Input
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
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Processor
Processor
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Also called central processing unit (CPU)
The brain of a computer, the most important
component of a computer
Center of activity in the computer
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Consists of electronic circuits
Interprets and executes program instructions
Communicates with input, output, and storage devices
Actually transforms data into information
Examples
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Storage
Register
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Inside CPU, temporarily hold data
Primary storage, i.e., memory
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Used to temporarily hold data
After it is retrieved from input device and before it is
processed
After it is processed and before it is released to output
device
Temporary (volatile) storage. Data in memory lost if
power is lost or program closed
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Secondary storage
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Provides long-term storage
Separate from memory
Common media
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Magnetic disks
Diskette
Hard Disk
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Optical disks
Use a laser beam to read
large
volumes of data
inexpensively
CD-ROMs
DVD-ROMs
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Magnetic tape
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Output: What Comes Out
Output: the result produced by the CPU
Common forms of output: text, numbers,
graphics, and sounds
Common output devices:
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Screen (monitor): can display text, numbers,
photographs, even video, in full color
Printer: produces printed reports as instructed
by a program
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Computer Screen Technology
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
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CRT Screens
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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Factors Affecting Performance
Scan rate
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The frequency with which the image is refreshed
Resolution (clarity) of screen
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Measured in pixels (picture elements)
The more pixels, the higher the resolution
Graphics standards exist
Dot pitch
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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
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Graphic Standards
Agree on resolutions, colors, other issues
related to displaying graphics
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Super Video Graphics Adapter (SVGA) is
most common standard
Provides 800 (horizontal) x 600 (vertical) pixels on
the display
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Other varieties of SVGA exist
Support 16 million colors
The number of colors that can be displayed
depends on amount of video memory
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Flat-Panel Screens
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
Flat-panel technologies
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LCD Technologies
Active-matrix
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Uses many thin-film transistors (TFT)
Produces brighter image and can be viewed from
wider angles
Passive-matrix
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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
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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
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Printers
Produce information on paper output
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Printed output known as hard copy
Orientation settings
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Portrait - vertical alignment
Landscape - horizontal alignment
Two ways of printing
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Impact printer
Nonimpact printer
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Impact Printers
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
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Nonimpact Printers
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
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Voice Output
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
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Music Output
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
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Terminals
Combine input and output capabilities
Dumb terminal
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Keyboard for input and monitor for output
No processing capability
Intelligent terminal
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Has limited memory and a processor
Point-of-sale (POS) terminal
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Captures retail sales data when transaction
takes place
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Program / Software
A program is a set of instructions that tells a
computer what to do
An instruction is a fundamental operation that a
CPU does, such as an addition of two numbers,
save/load data to/from memory, etc.
A program runs on a computer to carry out a
desired task.
Operating system software
Application software
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Program / Software
A program is a set of instructions that tells a
computer what to do
An instruction is a fundamental operation that a
CPU does, such as an addition of two numbers,
save/load data to/from memory, etc.
A program runs on a computer to carry out a
desired task.
Operating system software
Application software
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Application Programs
Information processing
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Word-processing
Spreadsheet
Database
Statistics
Scientific computation
Internet, WWW.
Entertainment
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Audio, Music
Video
Computer aided design and manufacture
Control
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Industrial process control
Airplane, ship, car, satellites, space vehicles, robots
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Networking
Network: a system that uses
communications equipment to connect
computers and their resources
Common network tools:
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Local Area Network (LAN)
Modem
Electronic mail
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Local Area Network
Personal computers in an office are
connected so users can communicate
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Users can operate computers independently
Can share resources and exchange data
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Modem
A device that allows users to communicate
with other computers over telephone lines
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Required when you don’t have a digital
connection such as DSL or a cable modem
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Electronic Mail (e-mail)
Send and receive messages electronically
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Can send text, pictures, links to Web sites
Can attach files for collaboration
Messages stored in computer “mailbox”
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The Internet
The largest and most far-flung network
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Connects users worldwide
Not actually a network, but a collection of
thousands of networks
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Getting Connected
To access the Internet, connect to a server
computer
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Server receives, processes, and transmits
information
Computers use a standard to communicate
Need an Internet Service Provider (ISP)
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Internet Service Providers
The owner of a server computer
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Charges a fee for access to the Internet
Fee can provide unlimited access or be based on
usage
Provides the user a means to connect to
the server
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Once connected, you can connect to the
Internet and all other server computers
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Computer Protocols
Provides a standard way to communicate
with other computers
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Transmission Control Protocol/Internet
Protocol (TCP/IP) used on the Internet
Allows different types of computers to share
data
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Getting Around the Internet
Began as a means for Department of
Defense and its research institutions to
share information
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Information was text-only
Commands to navigate were obscure
Now, much more visually based
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Use browser to explore the Internet
World Wide Web
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Browser
Software that allows you to use a mouse to
explore the Internet
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Click on screen text and/or graphics to move to
different locations
Most commonly used to explore the World Wide
Web
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The World Wide Web
A subset of the
Internet
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Actually, a standard
for displaying and
transmitting
information
Web site: a location
on the Web
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Home page: the main
page of a Web site
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Classification of Computers
Personal Computers
Notebook Computers
Handheld Computers
Midrange Computers
Mainframes
Supercomputers
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Personal Computers
Desktop computers
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Also known as PCs, microcomputers, or home
computers
Broken down into three categories:
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Low-end computers
Fully-powered personal computers
Workstations
Network computer
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Central processing unit and minimal memory
Designed to be used on a network
Sometimes called thin client
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PC Categories
Low-end computers
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Fine for home users, word processing, simple games,
Internet access
Fully powered computers
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Good for heavy use of graphics, programming, or
action-oriented games
Workstations
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Very high-end computers used by engineers, financial
traders, and graphic designers
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Notebook Computers
Small, lightweight computers
Capabilities approach that of
desktop computers
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Similar processing and memory
Most have hard disk, and
diskette or CD-ROM drive
Typically more expensive
than comparable desktop
computers
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Handheld Computers
Personal Digital Assistant
(PDA)
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Keeps track of appointments,
contacts, etc.
Accepts input with hand-held
stylus
Pocket PC
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Offers capabilities of PDAs, plus
the ability to run stripped-down
versions of software such as word
processing and spreadsheets
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Midrange Computers
Multi-user computers designed to serve
the needs of medium-sized organizations
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Hundreds or thousands of users connected
Used for inventory, order-entry, and other
company-wide applications
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Mainframes
Very large and powerful computers
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Capable of processing billions of instructions
per second
Capable of handling billions of characters of
data
Often used for applications with many users
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Reservations systems
Large mail-order houses
E-mail servers
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Supercomputers
The fastest and most
powerful computers
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Capable of processing trillions
of instructions per second
Used for very sophisticated
applications requiring
mammoth data manipulation:
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Weather forecasting
Weapons research
Special effects for movies
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Benefits of Computers
Productivity
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Workers use computers to do their jobs faster and better
Many processes can be more efficiently controlled by
computers
Decision Making
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Helps decision makers sort out financial, geographical,
and logistical factors
Cost Reduction
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Helps hold down costs of labor, energy and paperwork
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What we care about a computer?
Speed
Reliability
Storage Capability
Security
By-products
Cost
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