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Chapter 6
System Software: Operating Systems and Utilities
System Software vs. Application Software
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System software acts as a mediator between application programs and the
hardware resources of the computer system.
Application software provides the tools to perform particular tasks on a PC, such as
writing a letter, processing orders, playing games, composing an e-mail, and so forth.
The Operating System
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A computer’s operating system is the collection of programs that manage and
coordinate the activities of the computer system.
Primary responsibilities are management and control.
The operating system is the go-between, meshing the user’s application program with
the resources of the system.
Functions of an Operating System
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To boot up (start up) the computer and configure devices.
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During the booting procedure, the operating system determines what hardware devices
are online, makes sure that its own files tell it how to deal with those devices, and reads
an opening batch of directives.
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Plug-and-play devices can be recognized when they are first connected and configured
with little input or work needed from the user.
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To interface with users. As soon as the user enters keystrokes or clicks a mouse, the
operating system passes the digitally coded instructions to the CPU for processing.
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Managing system resources and jobs. Scheduling routines in the operating system
determines the order in which jobs are processed.
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File management—allowing the user to store and manage files on storage media. Files
are commonly organized into folders, which can contain documents and subfolders. A
path specifies the exact location of a document.
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Security procedures, such as passwords for accessing the system and particular drives or
files, as well as user profiles.
Processing Techniques for Increased Efficiency
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With multitasking, the computer can work on several programs or tasks concurrently.
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Multitasking on a multiuser operating system is referred to as multiprogramming.
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Multithreading operating systems have the ability to process multiple threads (sequences
of instructions within a program that aren’t dependent on other threads) at one time.
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Time-sharing is a technique in which the operating system cycles through all the active
programs in the system that need processing, giving each one a small slice of time on
each cycle.
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In a time-sharing system, it is difficult for a single program to dominate the CPU’s
attention, thereby delaying the processing of shorter programs.
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With multiprocessing and parallel processing, two or more CPUs are used inside a single
computer system to perform work faster.
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Memory management refers to optimizing the use of RAM. Explain that some operating
systems use virtual memory as an expansion of RAM (refer the students to Figure 6-7).
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Spooling refers to using RAM or hard drive space (called a buffer or queue) to store input
on its way into the computer or output destined for a printer.
Memory management, such as the use of virtual memory.
Buffering and spooling
 A buffer is an area in RAM or on the hard drive to hold input and output on their
way in or out of system.
 The process of placing items in buffer so they can be retrieved by appropriate
device is spooling.
Differences Among Operating Systems
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Command line vs. graphical user interface.
Personal vs. network operating systems.
Types and numbers of processors supported.
Operating Systems for Desktop PCs and Servers
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PC operating systems are usually designed for use on either:
 Desktop PCs (personal operating systems)
 Network servers (network operating systems)
Some operating systems have versions for both; some personal operating systems
have limited networking capabilities.
DOS
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PC-DOS and MS-DOS were the dominant operating systems until the early 1990s.
DOS traditionally used a command-line interface; it is not widely used today.
Windows
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Many versions of the Windows operating system have existed over the last several
years.
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Windows 3.x (an operating environment over DOS, not an operating system).
Windows 95 and Windows 98 (personal operating systems).
Windows Me (personal operating systems for home PCs).
Windows NT (network operating system).
Windows 2000 (network and professional operating system).
Windows XP (latest version that replaces both Windows 2000 and Windows Me for home
and office PCs; based on Windows NT).
Windows Server 2003 (latest network version).
Mac OS
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Mac OS is the proprietary operating system used with Apple computers.
Mac OS has a graphical user interface.
The newest version is Mac OS X Version 10.3.
UNIX
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UNIX is a commonly-used, high-end PC and server operating system.
Not built around any one particular family of microprocessors—can be used on a
variety of computers.
Though traditionally a command line operating system, newer versions of UNIX use a
GUI.
Linux
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Linux is a version of Unix originally created in 1991.
Linux is open-source software; has been collaboratively modified by volunteer programmers
all over the world.
Traditionally a command line operating system; many versions now use a GUI.
Recent increased support from big name companies (Sun, IBM, HP, and Novell, for instance)
has increased the use and support of Linux.
NetWare
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One of the most widely used operating system on PC-based networks.
NetWare provides a shell around the users’ local desktop operating systems so they
can interact with network resources.
OS/2 and OS/2 Warp
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OS/2 is an operating system designed by IBM for high-end PCs.
Available in both server and client versions (for accessing an OS/2 server).
The newest versions is called OS/2 Warp 4.0.
Solaris
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Designed for Sun computers.
Can run on desktop PCs, servers, and some supercomputers.
The latest version is Solaris 9.
Operating Systems for Handheld PCs and Mobile Devices
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Windows Embedded—designed for non-personal computer-based devices (e.g.
cash registers).
Windows Mobile—designed for handheld PCs, smart phones, and other mobile
devices.
Palm OS—designed for Palm handheld PCs.
Symbian OS—designed for use with smart phones.
Operating Systems for Larger Computers
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Larger computers typically used operating systems designed specifically for that type
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of system.
Many mainframes and supercomputers today are running Linux.
A group of Linux PCs linked together to computer at supercomputing levels is called
a Linux supercluster.
Utility Programs
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Utility program—a type of systems program written to perform a specific system
task, usually related to managing or maintaining the system.
Many utilities are built into operating systems as well as being available as standalone programs.
File management programs—allow you to look at and manage the files stored on
your PC (copy, move, organize into folders, etc.).
Antivirus programs—find and eliminated computer viruses on your PC.
 Should be set up to run continuously and scan incoming files and e-mail
messages.
 Should be set up to do a complete scan of your PC about once per week.
 Need to be updated on a regular basis.
Diagnostic programs—evaluate the computer system and make recommendations
for fixing any errors found.
Disk management programs—diagnose and repair problems related to the hard
drive.
 Disk defragmentation programs rearrange the files on a hard drive to store them in
contiguous locations to speed up performance.
Uninstall utilities remove programs from your hard drive without leaving bits and
pieces behind.
 Programs should never be deleted from the hard drive without using an uninstall
procedure, unless there is no other alternative.
File compression programs make files smaller for archiving or sending over the
Internet.
 Compression programs can both compress (zip) and decompress (unzip) files.
 Common programs are WinZip for Windows users and Stuffit for Mac users.
Encryption programs are used to secure e-mail messages and files that are sent over
the Internet or other networks; can also be used with individual files stored on a hard
drive.
Network and Internet utilities include:
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Performance monitors
Logging programs
Directory services or identity management programs
Firewall programs
Antispam and e-mail filtering programs
The Future of Operating Systems
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Will likely continue to become more user-friendly.
May eventually be driven primarily by a voice interface.
Will likely be used to access an increasing number of Internet resources and
applications, such as Web based software and services.
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Will likely continue to support more synchronization between an individual’s various
computing devices, such as a desktop PC, handheld PC, and smart phone.
Key Terms
Antivirus program
Application software
Backup
Buffer
Command line interface
Computer virus
Cut and Paste
degfragment
Device driver
Directory
DOS (Disk Operating
System)
File compression
File management
GUI
Kernel
Linux
Mac OS
Mac OS X
Multiprocessing
Multitasking
NetWare
Network operating system
Operating system
Palm OS
Parallel processing
Path
Personal operating system
Plug-and-play
Spooling
Swap file
Symbian OS
System file
System software
UNIX
Utility program
Virtual memory
Windows
Windows 2000
Windows Embedded
Windows Mobile