A+ Guide to Software, 4e Chapter 1 Introducing Operating Systems

A+ Guide to Software, 4e

Chapter 1Introducing Operating Systems

A+ Guide to Software, 4e 2/28

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


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


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


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


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


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)


Figure 1-8 The Windows XP desktop and Start menu


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


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


UNIX

• Comprises a class of operating systems

• UNIX versions referred to as flavors or distributions

• Chief uses:– Controlling networks– Supporting Internet-based applications


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

http://www.novell.com/linux/suse

http://www.redhat.com/

http://www.turbolinux.com/


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


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


Figure 1-10 The Mac OS X desktop is intuitive and easy to use


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


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


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


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


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


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


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


Figure 1-30 The Windows XP desktop and Start menu


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


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


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


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

http://support.microsoft.com/


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

Documents

A+ Guide to Software, 4e Chapter 1 Introducing Operating Systems