Transcript Chapter 2 Information Systems Hardware

Information Systems
Hardware
Chapter 2
Chapter Objectives
• Understand the important role of IS
hardware in the success of modern
organizations
• Describe key elements of IS hardware
• List and describe the types of
computers used in organizations today
• Explain how hardware has evolved and
where it is headed
The Importance of Information
Systems Hardware
• Used in a rapidly changing, highly
competitive global economy
• Relied upon for the exchange of realtime information
• Used on a daily basis for work, school,
and fun
Key Elements of Information
Systems Hardware
Output
Processing
Input
Input: How Information is Entered
into an Information System
• The type of information determines how
it is input
– Text, numbers
– Drawings, designs
– Audio, video
Entering
Original Text / Numbers
• Keyboard is most common entry device
• Advanced keyboards are ergonomically
designed
Selecting and Pointing
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Mouse - most common pointing device
Trackball
Joysticks
Touch screens
Light pens
Entering Batch Data
• Used for entering large amounts of
routine information
• Scanners
– Convert printed text and images into digital
data
• Text recognition software
– Convert handwritten text to digital data
• Bar Code/Optical Character Readers
– Use light to scan magnetic data
Audio and Video
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Microphone
Digital cameras
Video cameras
Videocassette recorders
Processing: Transforming
Inputs into Outputs
• All input must be converted into
computer readable format
• Internal processing uses binary notation
– Binary consists of a series of 0’s and 1’s
– Each 0 or 1 is a bit
– A combination of eight bits is a byte
• ASCII represents numbers and letters in
binary code
Key Processing Elements
• Central Processing Unit (CPU)
– Interprets and executes commands
– Controls movement of data
• Primary storage
– Current
• Secondary storage
– Permanent
Figure 2.10
Processor
Primary
Storage
Keyboard
A
Secondary
Storage
B
C
D
Control
Instruct
CPU
Printer
Primary Storage:
Storage for Current Information
• Nonvolatile
– ROM (Read Only Memory)
• Holds instructions to start up the computer
• Volatile
– RAM (Random Access Memory)
• Stores data and program instructions the CPU
is currently working on
– Cache Memory
• Fast RAM for instructions queuing for
immediate processing by the CPU
Elements of Computer
Storage
Name
# of Bytes
Kilobyte
Megabyte
Gigabyte
Terabyte
1,000
1,000,000
1,000,000,000
1,000,000,000,000
Abbreviation
KB
MB
GB
TB
Secondary Storage: Keeping
Information for Later Use
• Permanent storage of data and
programs
– Magnetic tape
– Floppy disks
– Fixed disks
– Compact discs
– Optical disks
Magnetic Tape
• Same medium as audio cassette tapes
• Data stored by magnetically rearranging
atoms on tape
• Uses sequential data access
• Primarily used for backing up large
amounts of data
Files
Files
Files
Files
Floppy Disks
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Small magnetic disks
Transfer data between computers
Use direct data access (random access)
2.5” disk holds 1.44 MB
Iomega’s ZIP disk can store 100 MB
Fixed Disks
• Several magnetic platters in a sealed
container
• Read/Write heads for each platter surface
• Greater storage capacity and data
transfer rate than floppy disks
Read/
write
Heads
Multiple
Platters
CD-ROM (Compact Disc
Read-Only Memory)
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Uses the same technology as audio CD
Uses direct access
Holds 650MB
Slower than fixed disk
CD-R (CD-Recordable) drives available
Optical Disks
• Similar to CD-ROM technology
• May be rewritten many times
• Storage capacity of over 1 gigabyte
(GB) on a single disk
• Disks and disk players relatively
expensive
The Central Processing Unit:
The Brain of the Computer
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Calculates and manipulates data
Composed of millions of transistors
Operates on electronic impulses
Can perform more than a million
instructions per second
Output: How Information is
Displayed and Printed
• Output types are limited
– Video output
– Printer
– Sound
Video Output
• Monitors
– Most common video display
– Uses a cathode ray tube (CRT)
• Liquid crystal display (LCD)
– Used in portable computers
• Monitors embedded in many other
devices
Paper-Based Displays
• Printers
– Dot-matrix: form letters using a series of
small dots
– Inkjet: spray ink on paper from a small
cartridge
– Laser: use an electrostatic process to burn
ink to the paper
• Plotters
– Transfer designs to drafting paper
Audio Output
• Uses small speakers and a sound card
• Translates digitized data into sound
Types of Computers
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Supercomputers
Mainframes
Minicomputers
Workstations
Microcomputers
Supercomputers
• The most powerful and expensive
computers
• Contain numerous very fast processors
that work in parallel
• Used by researchers and scientists to
solve very complex problems
• Cost more than 1 million dollars
Mainframes
• The backbone of large corporate
computing
• The only type of computer that existed
30 years ago
• Used for enterprise-wide computing
Minicomputers
• Scaled down versions of mainframes
– Smaller
– Less expensive
• Declining market due to faster and more
powerful microcomputers
Workstations
• The power of a minicomputer
on a desktop
• Leaders in the market
– Silicon Graphics
– Sun Micro Systems
– DEC
• Process intensive applications
– Computer-Aided Design (CAD)
– Web Servers
Microcomputers
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Often called personal computers
Desktop models
Portable computers
Most commonly used computing
technology for knowledge workers
Evolution of Information
Systems Hardware
• Shifts in computing eras facilitated by
changes in computing technology
• Evolution marked by significant events
creating four generations of hardware
The First Generation:
Vacuum Tubes
• 1946 - 1958
• ENIAC: one of the first computers
– 1946
– Room-size with 18,000 vacuum tubes
• Replaced in 1950 by the UNIVAC
• Mainframe era begins
The Second Generation:
Transistors
• 1958 -1964
• Transistors generate less heat
• Transistors are smaller, faster, and more
reliable
• First transistors smaller than a dime
• Mainframe era continues
The Third Generation:
Integrated Circuits (IC)
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1964 -1990
Multiple transistors on a single chip
IBM 360 - First mainframe to use IC
DEC PDP-11 - First minicomputer
1975 - Altair 8800 first microcomputer
1981 - IBM introduced the PC
End of mainframe era, through mini era
to personal computing era
The Fourth Generation and
Beyond
• 1990 - Present
• Radical new applications
– Multimedia: the integration of voice, video
and data
– Internet for video conferencing
– End-user computing
The Future of Information
System Hardware
• Will continue the trend of smaller, faster,
cheaper and ubiquitous
• Virtual Reality
• Wearable Computing
• Smart Cards