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A+ Guide to Software, 4e
Chapter 1
Introducing Operating Systems
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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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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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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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 1-8 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 1-10 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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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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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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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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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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Figure 1-30 The Windows XP desktop and Start menu
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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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Figure 1-49 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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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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