No Class on March 30th

1. No Class on March 30th • CGS1060 lecture sections 5 and 6 on Wednesday morning will be cancelled on March 30th. • We will cover chapter 9 on April 6 and Chapter 11 on April 13. Exam 3 (the final) is still scheduled for April 20th. Operating Systems

2. Introduction toComputer Science Operating Systems

3. System Software • Controls the operations of the computer • Manages the operation of various computer components (CPU, hard drives, monitors, printers, etc.) • Includes • Operating System • Utility Programs Operating Systems

4. Functions of an OS start the computer provide a user interface manage programs administer security manage memory control a network provide file management and other utilities monitor performance establish an Internet connection schedule jobs and configure devices Operating Systems

5. Booting Up the Computer • Booting is starting or restarting a computer. • Cold boot is turning on a computer that has been turned off. • Warm boot is restarting a computer that has been on. • As the OS gets more complex and has to coordinate more things, RAM requirements get larger. Operating Systems

6. The Boot Process Step 4.Results of POST are compared with data in CMOS chip Step 1.Power supply sends signal to com-ponents in system unit Step 5.BIOS looks for system files 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 Operating Systems

7. Command-line Interface • Before computers used a graphical user interface (GUI), a command-line interface was used. • Even today, some operating systems use a command-line interface to conserve system resources and to make a more adaptable OS. Operating Systems

8. Menu-driven Interface • A menu-driven interface is a little easier to use than a command-line interface. • The PINE e-mail system uses a menu-driven interface. • Before GUIs were available, computer users would install menu-driven interface “shells” to work with their command-line interface OS. Operating Systems

9. Microsoft • Microsoft got its start creating operating systems such as DOS and Windows. • Microsoft also creates hundreds of application software titles and some hardware components. • Bill Gates is now the richest person in the world with a net worth of $40 billion. • He dropped out of college. Operating Systems

10. Windows OS (History) • Windows was created by Microsoft and “inspired” by the graphic interface used on the Apple Lisa and Macintosh, which debuted in 1983. • Mac OS was “inspired” by a GUI used by the XEROX Star in 1981. Operating Systems

11. Windows OS (History) • The most popular operating system for personal computers • Windows 1.0 released in 1985 • Windows 3.0 released in 1990 • Windows 3.1 released in 1992 • Uses a GUI for ease-of-use Operating Systems

12. Windows 95 released in the summer of 95, although it was planned for release at Christmas, 1994. Windows no longer served as a “middleman” between the user and the text-based DOS. Windows 95 took over and became the true operating system. Windows OS (History) Operating Systems

13. Windows OS (History) • Windows 98, Me, 2000, and XP take us into recent history. • Integrated Internet application and features • Integrated multimedia support Operating Systems

14. Mac OS • Operating system used on Macintosh computers, including the iMac. • Mac OS has been a trend setter in the area of graphical user interfaces (GUIs) Operating Systems

15. The Kernel • When the system files are found, the kernel (core of the OS) is loaded into RAM. • Parts of the OS that are not needed frequently stay on the hard disk and are called when necessary. • The kernel is memory resident -- it stays in memory Operating Systems

16. User Interface • After the kernel loads into RAM, the interface displays, allowing the user to start using the computer. • The interface is a Graphical User Interface (GUI). • A GUI is known to have icons and pull-down menus that can be controlled by a pointing device. Operating Systems

17. Multitasking • Working on two or more applications at the same time. One program can function in the background, while another program is being actively used. • With Windows and other popular OSs, I can have several programs open (in memory) at the same time and switch back and forth. Operating Systems

18. Memory Management • Because so many programs need to be stored in RAM, and because RAM is limited in size, it must be managed to be efficient. • The OS assigns items into memory while they are being used, and removes them when they are no longer needed. • The OS may use a portion of the hard drive to store items. This is called virtual memory. It is not real memory, but it is being used like memory. • Virtual memory cannot be accessed as fast as RAM. Operating Systems

19. Scheduling Jobs • The OS schedules jobs in an orderly fashion. • This is most obvious for print jobs. • I can have 3 Word documents open and 2 PowerPoint presentations. I click print for each one • The OS puts the print jobs into a queue (line). This is called print spooling. • Each job goes to the printer one by one, and I don’t have to wait. Operating Systems

20. Configuring Devices • Each piece of hardware on or in the computer is a device and has a special device driver (small program) that tells the OS how the device is supposed to operate. • You need a device driver for each device. • The OS keeps tracks of all of these drivers so that the various pieces of hardware can be managed. Operating Systems

21. Plug and Play • Allows for easy installation of new hardware. • The OS recognizes that you’ve attached a new hardware device • Then, it starts a wizard to help you install the necessary drivers. • Drivers for some common hardware can be found on the Windows CD, but you can also download drivers from the hardware vendor’s Web site. Operating Systems

22. Unix and Linux • UNIX is a text-based OS (like DOS) that is very popular as a network OS. • Because it is text-based (command line), it doesn’t require as much RAM or processing power as a Windows NOS • UNIX was made very affordable to universities, and is a popular NOS. • Linux is a free OS often used for network and web servers. • Developed by Linus Torvalds in the early 90s as a UNIX clone to work on PCs. • Linux is open-source, allowing for rapid popularity and improvements. Operating Systems

23. Monitoring Performance • The OS keeps tracks of things like the CPU, disks, memory, and network usage. • If too many programs are trying to run simultaneously, the OS sends an error stating that you are running low of memory, and must close some programs. Operating Systems

24. File Management • File Manager is called Windows Explorer in recent versions of Windows • Allows the user to keep track of disks • Shows the contents of disks • Available space • Disk format options • Assists with copying and moving files Operating Systems

25. Utility Programs • Included with the OS and used to perform a variety of specific tasks • File Viewer • File Compression • Diagnostics • Installer/Uninstaller • Disk Scanner • Disk Defragmenter • Backup Utility Operating Systems

26. File Compression • Takes a single large file or group of files and compresses them into a smaller, single file • Takes up less space on the hard disk • Allows for faster transfer via e-mail • Person receiving the compressed file must uncompress it before using the file. Operating Systems

27. Installer/Uninstaller • Installer keeps track of install information to make for easier removal of the program when it is uninstalled. • Uninstall will remove the program, and also remove different icons or registry lines referring to the program Operating Systems

28. Disk Scanner • Checks the recordable surface of the hard disk for errors. • Repairs them if possible • The disk scanner also searches for and removes temporary files that take up space and no longer serve a purpose. Operating Systems

29. Disk Defragmenter file before defragmenting fragmented disk file after defragmenting • A single file that can’t fit on a single sector, may be spread on multiple sectors all over a disk • Defragmenting puts the pieces next to each other to allow for faster access. Operating Systems

30. Backup Utility • Walks you through the process of saving important files to some other storage media (ZIP disk, CD, external drive, etc.) • Files may be compressed so that many files can be put on one disk. • A restore program is necessary to decompress the files back to a usable state. Operating Systems

31. Stand-alone Utility Programs • Many utility programs come with the OS, but you should also consider buying/installing stand-alone utilities: • Antivirus software • Checks your computer and e-mails for known viruses • Personal Firewall • Keeps unrequested network/Internet traffic from coming into your computer. • File Compression • Working with groups of files is easier if they are compressed into one file. Operating Systems

32. Stand-alone DOS Windows 3.x Windows 95 Windows NT Workstation Windows 98 Windows 2000 Professional Windows Me Windows XP Home Windows XP Professional Mac OS X OS/2 Warp Client UNIX Linux Network NetWare 2000 Server Windows 2003 Server OS/2 Warp Server UNIX Linux Solaris Embedded Windows CE Pocket PC 2003 Palm OS Symbian OS Types of Operating Systems Operating Systems

33. Controlling a Network • A Network OS (NOS) is an OS designed specifically for servers—computers used by networked users. • Home editions of Windows allow for you to set up client-to-client networks very easily. • To allow dozens (or hundreds) of users to access one computer, a server with a NOS installed will be necessary. Operating Systems

34. Windows 2000/2003 Server • Microsoft makes a line of network operating systems that provide for the special needs of a server computer. • Depending on the size and needs of the business, the NOS used may be the older Windows NT or the newest Windows 2003 server. Operating Systems

35. UNIX and Linux • Although they can be used as stand-alone operating systems, UNIX and Linux have reputations for being very stable network operating systems. • UNIX is extremely popular. It is more affordable than Windows 2003 and takes up fewer system resources. • Linux is open-source software and free to use and modify. Many networks use a Linux OS. Operating Systems

36. Security • Servers have greater need for security because large numbers of users access the computer and the computers contain information that is important to the success of the business. • Log on information (user name and password) are necessary • Access to certain files/folders may be restricted based on the identity of the user and the time of day. Operating Systems

37. Embedded OS • Handheld computers require an OS to manage their functions as well. • Because of their small size, they don’t have the capacity to store a full-features OS like you would use on a desktop computer. • An embedded OS is stored in a ROM chip Operating Systems

38. No Class on March 30th • CGS1060 lecture sections 5 and 6 on Wednesday morning will be cancelled on March 30th. • We will cover chapter 9 on April 6 and Chapter 11 on April 13. Exam 3 (the final) is still scheduled for April 20th. Operating Systems

39. The End • Make sure you carefully read this chapter after going through this presentation on your own and in lecture. • Don’t feel like you have to read the whole chapter at once. Read five pages at a time, but do it. • Pay special attention to the terms in bold type. Can you define them without the book? • Use the included review material at the end of the chapter. This will help solidify what you’ve read. Operating Systems