3 COMPUTER SOFTWARE Chapter Chapter 3 SAK3002 – Information Technology and Its Application

Objectives of this chapter: You can… Identify the types of system software Describe the functions of an operating system Identify the types of operating system Identify utility programs Explain the purpose of the utilities program Chapter 3 SAK3002 – Information Technology and Its Application

Overview This chapter covers System Software Operating System Utility Program GO! Chapter 3 SAK3002 – Information Technology and Its Application

Introduction Computer software is: A group of programs that connects user with computer devices Comprised of a sequence of instructions Designed to instruct the computer to execute desired functions by the users Chapter 3 SAK3002 – Information Technology and Its Application

Introduction (cont’d) Software Layers Chapter 3 SAK3002 – Information Technology and Its Application

Programs that maintain operation of computer System Software What is system software? Programs that maintain operation of computer Two categories Operating Systems Utility Programs Chapter 3 SAK3002 – Information Technology and Its Application

3.1 Operating System Chapter 3 SAK3002 – Information Technology and Its Application

Operating System What is an operating system? A group of programs that organize and manage the whole computer operations OS is a set of instructions that coordinate all the internal activities among computer hardware, application programs and users Chapter 3 SAK3002 – Information Technology and Its Application

Operating System (cont’d) OS is controlled by the kernel. What is a kernel? Kernel is the supervisor program that manage the memory and devices Kernel is loaded into the memory from the hard disk (or other storage) during booting until computer is turned off It is known as memory resident (because it resides in memory as long as the power is on. Non-resident are other programs that resides in hard disk at the same time) Chapter 3 SAK3002 – Information Technology and Its Application

Operating System (cont’d) The functions of an operating system start the computer (Booting) manage programs provide a user interface administer security manage memory control a network establish an Internet connection monitor performance schedule jobs and configure devices provide file management and other utilities Chapter 3 SAK3002 – Information Technology and Its Application

Operating System (cont’d) Booting Process of starting or restarting a computer Cold boot Turning on computer that has been powered off Warm boot Restarting computer that is powered on Chapter 3 SAK3002 – Information Technology and Its Application

Operating System (cont’d) A personal computer boot up process Step 1. Power supply sends signal to com-ponents in system unit Step 4. Results of POST are compared with data in CMOS chip Step 5. BIOS looks for system files on a USB drive, in floppy disk drive or CD/DVD drive, and then hard disk Step 2. Processor accesses BIOS to start computer Step 6. Kernel (core) of operating system loads into RAM Step 3. BIOS runs tests, called the POST, to check components such as mouse, keyboard, and adapter cards Step 7. Operating system loads configuration information and displays desktop on screen Chapter 3 SAK3002 – Information Technology and Its Application

Operating System (cont’d) 4 main functions of OS: Manage computer programs Manage computer hardware Provides user interface Support application software Chapter 3 SAK3002 – Information Technology and Its Application

Operating System (cont’d) Manage computer programs Managing programs refers to how many users, and how many programs, an operating system can support at one time An OS can be single tasking, multi-tasking, cooperative multi-tasking, preemptive multi-tasking, multithreading and multiprocessing Single tasking Runs only one program at a time Chapter 3 SAK3002 – Information Technology and Its Application

Operating System (cont’d) Multi-tasking Same concept as multiprogramming Allows 2 or more programs at the same time Divide the programs into active and inactive. Active application is called foreground application and inactive application is background application CPU does not run the programs simultaneously but manage the resources i.e. memory based on active/inactive applications Chapter 3 SAK3002 – Information Technology and Its Application

Operating System (cont’d) Cooperative Multi-tasking Based on multi-tasking concept, whereby foreground application controls CPU until program ends But if program crashes/hang, OS needs to be rebooted Preemptive Multi-tasking Based on multi-tasking concept But if program crashes/hang, OS is able to take over CPU so other programs can be maintained Chapter 3 SAK3002 – Information Technology and Its Application

Operating System (cont’d) Multithreading One program may execute more than one task Example print and edit at the same time Multiprocessing Use of 2 or more processor at the same time Programs run simultaneously Each processor manage own resources Hardware dependant esp. motherboard Chapter 3 SAK3002 – Information Technology and Its Application

Operating System (cont’d) Manage computer hardware Memory Unit OS partitions the memory for each program. If memory is insufficient, OS may use virtual memory, which allocates a portion of a storage medium to function as additional RAM In virtual memory, programs/instructions are stored in fixed-sized unit called pages If memory if full, OS will copy pages into swap file in hard disk and reloaded into memory when needed Chapter 3 SAK3002 – Information Technology and Its Application

Operating System (cont’d) With virtual memory (VM), portion of hard disk is allocated to function as RAM Step 1. The operating system transfers the least recently used data and program instructions to disk because RAM is needed for other functions. Step 2. The operating system transfers data and program instructions from hard disk to RAM when they are needed. Chapter 3 SAK3002 – Information Technology and Its Application

Operating System (cont’d) Input/Output Devices OS provides interrupt handler, a mini program to handle interrupt from input/output devices. Examples of interrupt are mouse click/scroll/keyboard punch OS requires device driver to operates hardware devices. Drivers are loaded during booting Chapter 3 SAK3002 – Information Technology and Its Application

Operating System (cont’d) What is a device driver? Device Driver Program that tells operating system how to communicate with device With Plug and Play, operating system automatically configures new devices as you install them Also called driver Chapter 3 SAK3002 – Information Technology and Its Application

Operating System (cont’d) Spooling Sending print jobs to buffer instead of directly to printer Print jobs line up in queue Chapter 3 SAK3002 – Information Technology and Its Application

Operating System (cont’d) Provides User Interface OS manages communication between the computers and users Users may login, run application programs, manage files (copy/save) and on/off computers using any type of interface There are 3 types of command instructions: Command line Instructions to be typed in i.e. to save a file into diskette is C:\WINDOWS>copy C:myfile.doc a: Users have to memorize instructions Chapter 3 SAK3002 – Information Technology and Its Application

Operating System (cont’d) Menu-driven User selects instruction from a text-based pull-down menu Instructions are entered either via mouse click/ keyboard <ENTER> of arrow keys Graphical user interface (GUI) User selects instruction by mouse click or keyboard <ENTER> icons Chapter 3 SAK3002 – Information Technology and Its Application

Operating System (cont’d) User interface Controls how you enter data and instructions and how information displays on screen command-line interface menu-driven interface Chapter 3 SAK3002 – Information Technology and Its Application

Operating System (cont’d) Graphical User Interface (GUI) User interacts with menus and visual images such as icons and buttons Chapter 3 SAK3002 – Information Technology and Its Application

Some characteristics of operating systems Proprietary software Privately owned and limited to specific vendor or computer model Device-dependent Runs only on specific type of computer Device-independent Runs on many manufacturers’ computers Downward compatible Works with application software written for earlier version of operating system Upward compatible Runs on new versions of operating system Chapter 3 SAK3002 – Information Technology and Its Application

Three categories of operating systems Embedded Network Stand-alone Chapter 3 SAK3002 – Information Technology and Its Application

Operating System (cont’d) Windows Version Year Released Windows 3.x 1990 Windows NT 3.1 1993 Windows 95 1995 Windows NT Workstation 4.0 1996 Windows 98 1998 Windows Millennium Edition 2000 Windows 2000 Professional 2000 Windows XP 2001 Windows XP SP2 2004 Windows Vista 2006 Stand-alone operating systems Example: Windows Chapter 3 SAK3002 – Information Technology and Its Application

Stand-Alone Operating Systems Windows XP Fast, reliable Windows operating system Available in five editions: Home Edition, Professional Edition, Tablet PC Edition, Media Center Edition, and 64-bit Edition Chapter 3 SAK3002 – Information Technology and Its Application

Stand-Alone Operating Systems Windows Vista Successor to Windows XP, containing a new interface and new / enhanced features Available in several editions, grouped into Home and Business categories Chapter 3 SAK3002 – Information Technology and Its Application

Stand-Alone Operating Systems Mac OS X Available only for computers manufactured by Apple Macintosh operating system has been model for most GUIs Chapter 3 SAK3002 – Information Technology and Its Application

Stand-Alone Operating Systems UNIX Used by power users because of its flexibility and power Most versions offer GUI Available for computers of all sizes Chapter 3 SAK3002 – Information Technology and Its Application

Stand-Alone Operating Systems Linux Popular, free, multitasking UNIX-type operating system Open-source software— code is available to public Both a stand-alone and a network operating system Red Hat provides a version of Linux called Red Hat Enterprise Linux. Chapter 3 SAK3002 – Information Technology and Its Application

Operating System (cont’d) Network operating system Allows users to share printer, Internet access, files, and programs on a network Administers security by establishing user name and password for each user Chapter 3 SAK3002 – Information Technology and Its Application

Network Operating Systems NetWare Designed for client/server networks Examples of network operating systems Windows Server 2003 Upgrade to Windows 2000 Server UNIX / Linux Multi-purpose operating system Solaris Version of UNIX developed by Sun Microsystems Specifically for e-commerce applications Chapter 3 SAK3002 – Information Technology and Its Application

Embedded Operating Systems Found on most mobile computers, PDAs, and other small devices Windows CE is scaled-down version of Windows Chapter 3 SAK3002 – Information Technology and Its Application

Embedded Operating Systems Operating systems for PDAs Windows Mobile for Pocket PC Palm OS for Palm Chapter 3 SAK3002 – Information Technology and Its Application

Embedded Operating Systems Embedded Linux Scaled-down Linux operating system designed for PDAs, smart phones, smart watches, set-top boxes, Internet telephones, and other devices Chapter 3 SAK3002 – Information Technology and Its Application

Embedded Operating Systems Symbian OS Open-source, multitasking operating system designed for smart phones Make telephone calls, save appointments, browse Web, send and receive e-mail and faxes, and more Chapter 3 SAK3002 – Information Technology and Its Application

3.2 Utility Program Chapter 3 SAK3002 – Information Technology and Its Application

Utility program A small program that provides an addition to the capabilities provided by the operating system Performs maintenance-type tasks, usually related to managing a computer, its devices, or its programs. Chapter 3 SAK3002 – Information Technology and Its Application

OS Utility Program File manager Performs functions such as copying, renaming, deleting, and moving files Image viewer displays contents of graphics file when you double click on it Chapter 3 SAK3002 – Information Technology and Its Application

OS Utility Program Personal firewall Detects and protects a personal computer from unauthorized intrusions The latest update to Windows XP automatically enables the built-in personal firewall upon installation Chapter 3 SAK3002 – Information Technology and Its Application

OS Utility Program Uninstaller Removes a program and all associated files In Windows XP, uninstaller is in Add/Remove Programs in Control Panel Chapter 3 SAK3002 – Information Technology and Its Application

OS Utility Program Disk scanner Detects and corrects problems on hard disk Searches for and removes unnecessary files Chapter 3 SAK3002 – Information Technology and Its Application

OS Utility Program Disk defragmenter fragmented disk disk after defragmentation process Disk defragmenter Reorganizes files and unused space on hard disk so programs run faster Chapter 3 SAK3002 – Information Technology and Its Application

OS Utility Program Diagnostic utility Compiles technical information about hardware and some software Prepares report outlining problems Chapter 3 SAK3002 – Information Technology and Its Application

OS Utility Program Backup utility Copies selected files or entire hard disk onto another storage medium Most compress files during backup to require less storage space Chapter 3 SAK3002 – Information Technology and Its Application

OS Utility Program Screen saver Causes monitor’s screen to display moving image or blank screen if there is no activity for a specified time To secure computer, user configures screen saver to require password to deactivate Chapter 3 SAK3002 – Information Technology and Its Application

Stand-Alone Utility Programs Antivirus program Identifies and removes viruses in memory, storage media, and incoming files Must be updated frequently Chapter 3 SAK3002 – Information Technology and Its Application

Stand-Alone Utility Programs What is a virus? Potentially damaging computer program Affects computer without user’s knowledge An unusual message or image is displayed on the computer screen An unusual sound or music plays randomly The available memory is less than what should be available A program or file suddenly is missing An unknown program or file mysteriously appears The size of a file changes without explanation A file becomes corrupted A program or file does not work properly System properties change SIGNS OF VIRUS INFECTION Chapter 3 SAK3002 – Information Technology and Its Application

Stand-Alone Utility Programs Spyware Program placed on a computer without the user’s knowledge that secretly collects information about the user Often enters a computer as a result of a user installing a new program A spyware remover is a program that detects and deletes spyware Chapter 3 SAK3002 – Information Technology and Its Application

Stand-Alone Utility Programs Internet filters Programs that remove or block certain items from being displayed Anti-Spam Programs Web Filters Pop-up Blockers Chapter 3 SAK3002 – Information Technology and Its Application

Stand-Alone Utility Programs File compression utility Shrinks size of files to free up room and improve performance Compressed files are sometimes called zipped files Two popular utilities: Winrar and WinZip Chapter 3 SAK3002 – Information Technology and Its Application

Stand-Alone Utility Programs CD/DVD burning software Writes text, graphics, audio, and video files to a recordable or rewriteable CD or DVD Chapter 3 SAK3002 – Information Technology and Its Application

Stand-Alone Utility Programs Personal computer maintenance utility Identifies and fixes operating system problems and disk problems Some continuously monitor computer to identify problems before they occur Chapter 3 SAK3002 – Information Technology and Its Application

End of Chapter 3 Chapter 3 SAK3002 – Information Technology and Its Application