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A+ Guide to Managing and
Maintaining your PC, 6e
Chapter 2
Introducing Operating Systems
Objectives
• Learn about the various operating systems and the
differences between them
• Learn how an OS interfaces with users, files and
folders, applications, and hardware
• Learn about a few OS tools you can use to examine
and maintain a system
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Introduction
• A computer comprises hardware and software
– Physical devices are the visible component
– The controlling software component is not visible
• Computer technicians need to master both parts
• Chapter 1 provided an overview of hardware devices
• Chapter 2 introduces critical system software
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Operating Systems Past and Present
• What an operating system (OS) does:
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Manages hardware
Runs applications
Provides an interface for users
Retrieves and manipulates files
• The OS can be analogized to a “middleman”
• A computer needs only one operating system
• Operating systems have evolved to a complex form
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Figure 2-1 Users and applications depend on the OS
to relate to all applications and hardware components
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DOS (Disk Operating System)
• The first OS used by IBM computers/compatibles
• Where DOS can still be found:
– Specialized systems using older applications
– On troubleshooting disks or CDs
• Windows 3.x and DOS
– Windows 3.x provided a graphical interface
– Underlying OS functions were performed by DOS
• Windows 9x/Me uses DOS in the underlying OS
• Windows XP/2000 run DOS emulation programs
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Figure 2-3 Windows 3.x was layered between DOS
and the user and applications to provide a graphics
interface for the user and a multitasking
environment for applications
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Windows 9x/Me
• Refers to Windows 95, Windows 98, Windows Me
• Combine a DOS core with graphical user interface
• Designed to bridge legacy and newer technologies
– Backward-compatible with older systems
– Able to accommodate new technologies
• Cautionary note on minimum requirements
– May differ for upgrades and new installations
– May differ for installation and run-time operation
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Figure 2-5 Windows 9x/Me is the bridge from DOS to Windows NT
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Windows NT
• Two versions of Windows NT (New Technology):
– Windows NT Workstation for desktops
– Windows NT Server to control a network
• Best known feature: new OS core replacing DOS
• Avoid installing Windows NT
– Windows NT introduced many new problems
– Problems only solved in later versions of Windows
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Windows 2000
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Upgrades Windows NT (both desktop and server)
Improvements over Windows NT:
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A more stable environment
Support for Plug and Play
Device Manager, Recovery Console, Active Directory
Better network support
Features specifically targeting notebook computers
OS includes only qualified hardware and software
Windows 2000 is being phased out
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Windows XP
• Integrates Windows 9x/Me and Windows 2000
• Two main versions: Home Edition and Professional
• Noteworthy new features:
– Allows two users to logon and open applications
– Incorporates Windows Messenger and Media Player
– Adds advanced security, such as Windows Firewall
• Hardware requirements
– 64 MB RAM (128 MB recommended)
– 1.5 GB free hard drive space (2 GB recommended)
– 233-MHz CPU speed (300-MHz recommended)
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Figure 2-8 The Windows XP desktop and Start menu
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Windows Vista
• Next generation of Windows operating systems
• Code-named Longhorn
• Noteworthy new features:
– New graphical interface
– Revamped engine
– A new interface between it and applications
• Scheduled release dates:
– November 2006 for business editions
– January 2007 for consumer editions
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Windows Server 2003
• Refers to a suite of Microsoft operating systems:
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Windows Small Business Server 2003
Storage Server 2003
Server 2003 Web Edition
Server 2003 Standard Edition
Server 2003 Enterprise Edition
Server 2003 Datacenter Edition
• Not designed for use in a PC
• Not covered in this text
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UNIX
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Comprises a class of operating systems
UNIX versions referred to as flavors or distributions
Chief uses:
– Controlling networks
– Supporting Internet-based applications
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Linux
• Variation on UNIX created by Linus Torvalds
• OS kernel and source code are freely distributed
• Popular distributions:
– SuSE (www.novell.com/linux/suse)
– RedHat (www.redhat.com)
– TurboLinux (www.turbolinux.com)
• Used as both a server and a desktop
• X Windows: GUI shells for UNIX and Linux
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OS/2
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Jointly developed by IBM and Microsoft
Chiefly used in certain types of networks
Part of OS/2 was incorporated into Windows NT
OS/2 is not covered in this book
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Mac OS
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First introduced in 1984 with Macintosh computers
Current version: Mac OS X (ten)
Mac OS X can work on some Intel-based computers
Markets: education, desktop publishing, graphics
Noteworthy features:
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Support for graphics and multimedia capabilities
Use of the Finder program to provide the desktop
Superior Plug and Play capabilities
Excellent support for multitasking
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Figure 2-10 The Mac OS X desktop is intuitive and easy to use
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What an Operating System Does
• Four functions common to all operating systems:
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Providing a user interface
Managing files
Managing applications
Managing hardware
• All OSs also have similar core components
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Operating System Components
• Components common to all OSs: shell and kernel
• The shell exposes functions to users and applications
– Example 1: enables user to select a CD
– Example 2: enables application to print a document
• The kernel (core) interacts with hardware devices
– Example: passes a print request to a printer device
• Registry database and initialization files
– Used to store configuration information in Windows
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Figure 2-11 Inside an operating system, different
components perform various functions
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An OS Provides a User Interface
• Sequence of events occurring after PC is turned on
– The operating system is loaded
– Running OS provides an interface (desktop)
– OS awaits an event, such as a double-click
• A user can initiate an event in several ways:
– Click a menu item
– Enter a command in Run dialog or command console
– Double-click an icon
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Figure 2-12 Enter command lines in a Command Prompt window
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Figure 2-13 A menu-driven interface: Windows Explorer in Windows XP
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An OS Manages Files and Folders
• File system: organizes files and folders
• File systems used by Windows for hard drives:
– File Allocation Table (FAT): tracks disk space usage
– New Technology File System (NTFS): replacing FAT
• Organization of a hard drive or floppy disk
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Platter contains concentric tracks
Track contains 512 byte sectors
Cluster contains one or more sectors
Cluster is the smallest unit on disk for storing a file
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Figure 2-14 A hard drive or floppy disk is divided into tracks
and sectors; several sectors make one cluster
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Files and Directories
• File system hierarchy:
– Directories (called folders in Windows)
– Subdirectories (child directories)
– Files
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Directories can contain subdirectories and files
Directory table: lists subdirectories and files
Root directory: directory for a logical drive; e.g., C:\
Path: drive, directories, filename, and file extension
– Example: C:\wp\data\myfile.txt points to “myfile”
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Figure 2-15 A hard drive is organized into directories and
subdirectories that contain files
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Partitions and Logical Drives on a
Hard Drive
• Hard drives are organized into partitions
• Two types of partitions
– Primary: can only have one logical drive; e.g., C:\
– Extended: can have one or more logical drives
• Logical drive (sometimes called a volume)
– Formatted using a file system
– Has a root directory and subdirectories
• Disk Management tool
– Used to create/view partitions, format logical drives
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Figure 2-18 Use the Windows 2000/XP Disk Management
utility to see how a hard drive is partitioned
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An OS Manages Applications
• The OS installs and runs all other PC software
• Application: software providing services for users
• Applications rely on the OS for support operations
– Example: MS word relies on OS to manage memory
• Applications are typically tailored to a single OS
– Ensure that OS is suitable for a given application
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Installing Application Software
• Sources of application software:
– Internet, CDs, DVDs, or floppy disks
• Installation program is provided by application
• Tasks performed by installation program:
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Folders are created on the hard drive
Files are copied to the folders
For Windows, entries are made in Windows registry
Icons are usually placed on desktop
For Windows, entries are added to the Start menu
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Launching Application Software Using
the Windows Desktop
• An application has to be started before use
– You run, load, launch, or execute the application
• Four ways to run software:
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Use a shortcut icon
Use the Start menu
Use the Run command
Use Windows Explorer or My Computer
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Real (16-bit), Protected (32-bit), and
Long (64-bit) Operating Modes
• Bit type: number of bits simultaneously processed
• Real (16-bit) mode
– Exposes hardware to application (no longer used)
– Example: DOS
• Protected (32-bit) and Long (64-bit) modes
– OS controls how an application accesses hardware
– Preemptive multitasking is supported
– Example: Windows XP Professional x64 Edition
• Multiprocessing involves multiple CPUs
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16-bit, 32-bit, and 64-bit Software
• 16-bit software
– Written for Windows 3.x
– Data access is 16 bits at a time
• 32-bit programs
– Written for Windows NT/2000/XP and Windows 9x/Me
• 64-bit programs
– Written for Windows XP Professional x64 Edition
• Most software today is 32-bit or 64-bit
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An OS Manages Hardware
• OS interacts with hardware using drivers or BIOS
• Software falls into three categories:
– Device drivers or the BIOS
– Operating system
– Application software
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Figure 2-23 An OS relates to hardware by way of BIOS and
device drivers
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How an OS Uses Device Drivers to
Manage Devices
• Device drivers: specify how to interact with a device
– Example: a driver links a computer to a digital camera
• Drivers are provided by OS and device manufacturer
• Three kinds of drivers (corresponds to a mode)
– 16-bit real, 32-bit protected, and 64-bit long
• Device drivers in Windows
– Before installation, verify Microsoft has tested device
– Registry stores information about 32-bit device drivers
– Updated drivers are available at manufacturer’s site
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How an OS Uses System BIOS to
Manage Devices
• System BIOS contains device information
– Instructions enable CPU to communicate with device
– Example: keyboard activated at startup using BIOS
• Configure BIOS device interaction in CMOS setup
• The OS may use system BIOS to access devices
• Disadvantage of using BIOS device management
– BIOS does not operate as fast as device drivers
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How an OS Manages Memory
• Memory functions performed by OS at startup
– Launches utilities to manage memory
– Assigns addresses to each location of memory
• Drivers, OS, and application use memory addresses
– Enables three software layers to refer to shared data
• 16-bit program in real mode has direct access to RAM
• The OS controls memory access in protected mode
– The address spaces of a program is protected
– Virtual memory expands number of running programs
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Figure 2-27 Protected mode allows more than one
program to run, each protected from the other by
the operating system
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OS Tools to Examine a System
• A variety of tools are available:
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The Windows Desktop
My Computer and Windows Explorer
System Properties
Control Panel
Device Manager
System Information
Windows Help and the Microsoft Web Site
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The Windows Desktop
• Primary tool provided by the Windows shell
• Terms associated with the desktop
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Taskbar: displays information, offers program access
Service: support program running in the background
System tray: displays icons for running services
Shortcut: desktop icon pointing to a program
• Tools used to configure the desktop
– Display Properties Window
– The Taskbar and System Tray
– Shortcuts
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Figure 2-28 The Windows XP desktop and Start menu
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My Computer and Windows Explorer
• Used to manage files, folders, and other resources
• Tools share similar functionality
• Perform a wide range of tasks using shortcut menus
– Example: create a new file
• File and folder operations performed with Explorer
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Creating a folder
Deleting a folder
Changing file attributes
Changing folder options
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Figure 2-41 Create a new file using Windows Explorer
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System Properties
• Two ways to open utility:
– Right-click My Computer and select Properties
– Click the System applet in the Control Panel
• Some tasks that can be performed
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View processor and memory information
Change the name of the computer on the network
Access Device Manager on the Hardware tab
Control performance on the Advanced tab
Switch System Restore on or off
Use the Automatic Update tab to control updating
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Control Panel
• Contains applets used to manage the system
• Accessing Control Panel in Windows XP
– Click Start and the click Control Panel
• Two views: Category View and Classic View
• Applets can be launched via the Run dialog box
– Example: enter Main.cpl to open Mouse Properties
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Device Manager
• Primary graphical tool for solving hardware problems
• Primary screen displays a list of devices
– Right click Properties to view device details
• Some tasks that can be performed
– Enable, disable, uninstall a device
– Update device drivers
– Uninstall device drivers
• Symbols are used to indicate a device status
– Example: red X over device indicates it is disabled
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Figure 2-47 Windows XP Device Manager gives
information about devices and allows you to uninstall a
device
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System Information
• Used to view detailed information about the system
• Important features
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BIOS version you are using
The directory where the OS is installed
How system resources are used
Information about drivers and their status
• To open utility, enter Msinfo32.exe in Run dialog box
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Windows Help and the Microsoft Web
Site
• Key guide to system
• Excellent troubleshooting resource
– Example: analyze problem with Internet connection
• Microsoft Web site: http://support.microsoft.com
• Use search engine to locate alternative resources
– Ensure that the alternative site is reputable
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Figure 2-51 Troubleshooter making a suggestion to
resolve a problem with using the modem to connect
to the Internet
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Keystroke Shortcuts in the OS
• Simplify interaction with the operating system
• Examples
– Function keys: F4, F5, F8
– Text editing operations: Ctrl+C, Ctrl+V, Ctrl+x
• Shortcut keys are critical when mouse is not working
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Summary
• The OS manages system resources for users and
applications
• DOS (disk operating system): early commanddriven OS
• Modern OSs: Windows 2000/XP, Linux, Mac OS X
• Operating systems are divided into a kernel and
user shell
• Two OS running modes: real and protected
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Summary (continued)
• OS functions: providing a user interface, managing
files, managing applications, and managing hardware
• Windows desktop: primary graphical interface to OS
• Windows Explorer: used to navigate directory and
manipulate files and folders
• Other tools: System Properties, Control Panel, Device
Manager, System Information, and Windows Help
• Keystroke shortcuts provide a way to perform tasks
without a mouse
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