Technology In Action
Chapter 4
Using System Software:
The Operating System, Utility
Programs (and File Management)
© 2008 Prentice-Hall, Inc.
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Application Software
and System Software
• Application software helps people
carry out tasks using a computer
– word processing, spreadsheets, games
– music, databases, educational,
reference
• System software helps the computer
carry out basic operating functions
– operating systems
– device drivers, utilities, programming
languages
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System Software
Operating
System
• Control computer
functions:
– Hardware
– Memory
– Application
programs
– System
maintenance
• Provide user
interface
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System Utilities
• Programs that
perform computer
housekeeping tasks:
– Manage system
resources
– Improve efficiency
– Virus prevention
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What the Operating System
Does
• Provides a user
interface
• Manages the CPU
• Manages memory
• Manages hardware
• Coordinates
application
software with the
CPU
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The User Interface
• Enables you to
interact with the
computer
• Types of
interfaces:
– Command-line
interface (CLIs)
– Graphical user
interface
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Graphical User Interfaces
(GUIs)
• Mac OS, like Windows, bases their
user interface on the graphical model
pioneered at Xerox PARC
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MAC OS
• First operating system with point-and-click
technology (Graphical User Interface) (1984)
• Excellent in:
MAC OS X
– Graphics display
– Processing capabilities
– System reliability
– Document recovery
• Latest version OS-X
in 2000 based on
Unix
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Microsoft Windows
• one of first GUIs offered for an Intel
PC
• many different versions
• latest is Windows 7
UNIX
• Multiuser, multitasking operating
system
• Used with all sizes of computers
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UNIX
• UNIX is an operating system developed at
Bell Labs in the 60’s by Dennis Ritchie and
Ken Thompson
• Not built around any one particular family
of microprocessors—highly portable.
Example: basis of Apple's Mac OS X Tiger
• Often used in servers or work-horse
machines which must be very stable and
secure ( uptime )
• Newer versions of UNIX use a GUI and are
friendlier to use than the original OS.
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Linux
• Open-source
operating system
• Based on UNIX
• Stable, portable
system
• Free
• May be downloaded
through the
Internet
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Linux
• Linux is a version of Unix originally
created in 1991 by Linus Torvalds.
• Linux is open-source software; has
been collaboratively written by
volunteer programmers all over the
world.
• Recent increased support from big
name companies (Sun, IBM, HP, and
Novell, for instance) has increased
the use and support of Linux.
• Used on many web servers
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Linus Torvalds
CPU Management
• A computer can take advantage of
performance-enhancing technologies
– Multitasking (time sharing)
• Ctrl+Alt+Del, Alt+Tab - Task management
• Foreground, background
– Multithreading
divide a task
into threads
– Multiprocessing
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Operating System
Categories
• Three categories:
– Single-User, Single-Tasking
– Single-User, Multitasking
– Multiuser (must be multitasking)
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Single-User Operating
Systems
Single-task
systems
• Perform one task at a time
• PDAs:
– Pocket PC
– Palm OS
– Windows Mobile
Multitask systems
• Perform simultaneous
tasks
• Windows
• MAC OS
• Unix / Linux
• MS-DOS
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Multitasking
• An illusion!
• CPU has to juggle many jobs
• Each application gets a time slice
• Others are paused while one runs
• Fast enough to look simultaneous
Multitasking- Single core,
Dual core
Multiuser Operating
Systems
• Known as network operating systems
• Allow access to the computer system
by more than one user
• Manage user requests
• Systems include:
– UNIX
– Novell Netware
– Windows Server 2003
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Memory Management
• The operating system allocates space
in RAM for instructions and data
RAM
Operating
System
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Increased Efficiency
• Memory Management
– Virtual Memory - good!
– Memory leaks - bad!
• Buffering - A buffer is an area in
RAM or on the hard drive used to hold
input and output on their way in or out
of system.
– Print Queues
– Large File Downloads
– I/O Buffers
Chapter 3: Computer Software
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Virtual Memory
• Instructions and data are stored on
the hard drive when RAM is full
– Swap file
– Paging
– Thrashing
FULL
Operating
System
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Hardware Management
• Device drivers:
– Programs that enable
the operating system to
communicate with
peripheral devices
– Provided by the
manufacturer of the
device
• Plug and Play:
– Hardware and software
standard
– Facilitates the
installation of new
hardware
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Utility Programs
• Small application programs that
perform special functions:
– Manage system resources
– Create pleasant environment
– Improve efficiency
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Utilities
• Backup utilities
• File managers - Windows Explorer
• Screen savers
• File compression - WinZip
• Anti-virus protection
• Spam filters
• Encryption - PGP
• Defragmentation of storage
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Display Utilities
• Change the appearance of:
– Desktop
– Windows colors
– Font sizes
– Screen savers
• saving from what?
– Screen resolution
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Add or Remove Programs
• Installation wizard
• Uninstall wizard:
– Do not just delete programs from
Program Files folder!
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File Compression Programs
• Reduce the size of
a file:
– Removes
redundancies
– Some types of files
do not compress
well - JPG, MP3,
GIF, PNG
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System Maintenance
Utilities
• Disk cleanup
– Cleans
unnecessary files
• Recycle bin
• Temporary
Internet files
• Cached Web pages
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System Maintenance
Utilities
• Disk defragmenter
• ScanDisk:
– Error-checker
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System Maintenance
Utilities
• Task manager
– controls processes
and applications
– can halt one that is
out of control "Not
Responding"
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Restore Utilities
• Undelete
– How? Why?
• System
Restore:
– Restores the
system settings
back to a
specific date
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Accessibility Utilities
• Utility manager:
– Magnify screen
image
– Screen contents
narration
– On-screen keyboard
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