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A+ Guide to Managing and
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Chapter 2
Introducing Operating Systems (v0.92)
Introduction
• A computer comprises hardware and
software
– Physical devices are the visible
component
– The controlling software component is
not visible
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Operating Systems Overview
• The OS can be analogized to a
“middleman”
– Between the hardware and the
applications software
• A computer needs only one operating
system
• Operating systems have evolved to a
very large and complex software system
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Basic Function of an OS
•
•
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•
Manages hardware
Runs applications
Provides an interface for users
Retrieves and manipulates files
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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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Overview of OS Types
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DOS (Disk Operating System)
• The first OS used by IBM PC computers and
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
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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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DOS Still Lives!
• Windows 9x/Me uses DOS in the
underlying OS
• Windows XP/2000 run DOS emulation
programs
• Command prompt mode of
NT/2000/XP/Vista
• Recovery Console
– 2000/XP/Vista
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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
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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
• Completely new file storage system (NTFS)
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Windows 2000
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•
Upgrades Windows NT 4.0
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
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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
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Windows XP Requirements
• Installation 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
• Newest Windows OS
• (4) versions
• Noteworthy new features:
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New graphical interface
Revamped engine
A new interface between it and applications
New security features
DirectX 10 (games & multimedia)
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Vista Issues
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•
•
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•
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Hefty hardware requirements
Limited support for older hardware
Little hardware support for DirectX 10
Software compatibility problems
Performance
First edition issues
– SP1 released early 2008
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Windows Server 2003
• Refers to a suite of Microsoft operating systems:
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–
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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
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UNIX
•
•
•
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)
– Ubuntu
• Used as both a server and a desktop
• X Windows: GUI shells for UNIX and Linux
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OS/2
• Jointly developed by IBM and Microsoft
• Chiefly used in certain types of networks
• Part of OS/2 was incorporated into
Windows NT
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Mac OS
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•
•
•
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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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Operating System Components and
Functions
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Operating System Components
• Components common to all OS’s
– Kernel
– Shell
– Registry database and/or initialization
files
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OS Component Descriptions
• The shell exposes functions to users and
applications
– Graphical or command prompt
• The kernel (core) interacts with hardware devices
– Example: passes a print request to a printer device
• Registry database and initialization files
– 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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Basic Operating System Functions
•
•
•
•
Manages hardware
Runs applications
Provides an interface for users
Retrieves and manipulates files
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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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Operating System User Interfaces
• Command prompt
• GUI (Graphical User Interface
– Menu
– 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
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Storage Device Structure
• 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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Files and Directories (continued)
• 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:\
• Can be bootable
– Extended: can have one or more logical
drives
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Hard Disk Partitions
• 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
(obsolete)
• Installation program is provided by
application
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Installation Program Tasks
• 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
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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 mostly 32-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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Device Drivers in Windows
• Before installation, verify Microsoft has tested
device
– Windows XP/Vista use signed drivers
• 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
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OS Memory Access
• 16-bit applications program in real mode has direct
access to RAM
– Example: Under DOS
• The OS controls memory access in protected mode
– The address spaces of a program is protected
– Virtual memory expands number of running
programs
– Examples: Windows 2000/XP/Vista
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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
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Desktop Configuration Tools
• 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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Explorer File and Folder Operations
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•
•
•
•
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Creating a folder
Deleting a folder
Changing file attributes
Erasing a file
Renaming a file
Changing folder options
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Figure 2-41 Create a new file using Windows Explorer
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System Properties Utility
• Two ways to open the utility program:
– Right-click My Computer and select
Properties
– Click the System applet in the Control
Panel
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System Properties Utility (continued)
• 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
• Symbols are used to indicate a device
status
– Example: red X over device indicates it is
disabled
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Device Manager (continued)
• Some tasks that can be performed
– Enable, disable, uninstall a device
– Update device drivers
– Uninstall device drivers
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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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