Introducing Operating Systems

1
A Guide to Software, 4e

• Chapter 1
• Introducing Operating Systems

2
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

3
Introduction

• Personal computers have changed our lives
• You will gain a deeper understanding of the
  operating system
• Customize
• Troubleshoot
• Optimize
• Learn different operating systems
• What they do
• How they work to control the hardware

4
Operating Systems Past and Present

• What an operating system (OS) does
• 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

5
Figure 1-1 Users and applications depend on the
OS to relate to all applications and hardware
components
6
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

7
Figure 1-3 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
8
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

9
Figure 1-5 Windows 9x/Me is the bridge from DOS
to Windows NT
10
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
  

11
Windows 2000

• Upgrades Windows NT (both desktop and server)
• Improvements over Windows NT
• 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

12
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)

13
Figure 1-8 The Windows XP desktop and Start menu
14
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

15
Windows Server 2003

• Refers to a suite of Microsoft operating systems
  
• 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

16
UNIX

• Comprises a class of operating systems
• UNIX versions referred to as flavors or
  distributions
• Chief uses
• Controlling networks
• Supporting Internet-based applications

17
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

18
OS/2

• 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

19
Mac OS

• 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
• Support for graphics and multimedia capabilities
• Use of the Finder program to provide the desktop
• Superior Plug and Play capabilities
• Excellent support for multitasking

20
Figure 1-10 The Mac OS X desktop is intuitive and
easy to use
21
What an Operating System Does

• Four functions common to all operating systems
• Providing a user interface
• Managing files
• Managing applications
• Managing hardware
• All OSs also have similar core components

22
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

23
Figure 1-11 Inside an operating system, different
components perform various functions
24
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

25
Figure 1-12 Enter command lines in a Command
Prompt window
26
Figure 1-13 A menu-driven interface Windows
Explorer in Windows XP
27
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
• 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

28
Figure 1-14 A hard drive or floppy disk is
divided into tracks and sectors several sectors
make one cluster
29
Files and Directories

• File system hierarchy
• Directories (called folders in Windows)
• Subdirectories (child directories)
• Files
• 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
  

30
Figure 1-16 A hard drive is organized into
directories and subdirectories that contain files
31
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

32
Figure 1-19 Use the Windows 2000/XP Disk
Management utility to see how a hard drive is
partitioned
33
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

34
Installing Application Software

• Sources of application software
• Internet, CDs, DVDs, or floppy disks
• Installation program is provided by application
• Tasks performed by installation program
• 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

35
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
• Use a shortcut icon
• Use the Start menu
• Use the Run command
• Use Windows Explorer or My Computer

36
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

37
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

38
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

39
Figure 1-24 An OS relates to hardware by way of
BIOS and device drivers
40
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 manufacturers
  site

41
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

42
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
  

43
Figure 1-29 Protected mode allows more than one
program to run, each protected from the other by
the operating system
44
OS Tools to Examine a System

• A variety of tools are available
• The Windows Desktop
• My Computer and Windows Explorer
• System Properties
• Control Panel
• Device Manager
• System Information
• Windows Help and the Microsoft Web Site

45
The Windows Desktop

• Primary tool provided by the Windows shell
• Terms associated with the desktop
• 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

46
Figure 1-30 The Windows XP desktop and Start menu
47
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
• Creating a folder
• Deleting a folder
• Changing file attributes
• Changing folder options

48
Figure 1-43 Create a new file using Windows
Explorer
49
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
• 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

50
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

51
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

52
Figure 1-49 Windows XP Device Manager gives
information about devices and allows you to
uninstall a device
53
System Information

• Used to view detailed information about the
  system
• Important features
• 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

54
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

55
Figure 1-53 Troubleshooter making a suggestion to
resolve a problem with using the modem to connect
to the Internet
56
Keystroke Shortcuts in the OS

• Simplify interaction with the operating system
• Examples
• Function keys F4, F5, F8
• Text editing operations CtrlC, CtrlV, Ctrlx
• Shortcut keys are critical when mouse is not
  working

57
Summary

• The OS manages system resources for users and
  applications
• DOS (disk operating system) early command-
  driven 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

58
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