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CSC 1113 – Introduction to Computers
LECTURE NOTES – CHAPTER 5
I. THE OPERATING SYSTEM (OS): THE COMPUTER’S TRAFFIC COP CIYF
The most basic communication interface between a personal computer (PC) and the human is the operating system (OS). Explain that the operating system is basically a set of programs that perform certain functions and that all computers must have an operating system to handle essential tasks as input, output, and storage of information. Emphasize that the operating system is always running even when you are working with a particular program such as a word processor. You may have several applications running at the same time. This is called “ multitasking .” Explain that there are multiple operating systems, also called operating platforms. This is an important concept because the operating system and applications software must work closely together. It is true that some software applications are “cross-platform,” but for the most part applications are designed to work on a specific operating platform. Teaching Tip : Use an analogy to help students relate this concept to something they already know. In addition to the “traffic cop” analogy used in the textbook, try using the analogy of the operating system as the puppeteer, and various applications or programs as the puppets. Expand upon the analogy by stating that the traffic cop must speak the same language as the drivers and pedestrians; otherwise they will not be able to work together. The puppeteer must use the appropriate method to communicate with the puppets, or nothing will happen.
A. Starting the Computer
Explain that the process of starting the computer is known as booting. Explain what happens when you start or restart a computer, and compare cold boot to warm boot. Discuss the role of the kernel , or supervisor program , in the booting process. Address why the kernel is called a memory resident , and explain what a nonresident is.
1. The BIOS Screen and Setup Program. Pronounce BIOS “bye-ose.” Define BIOS as built-in software that determines what a computer can do without accessing programs from a disk. Because the BIOS is typically found on a ROM chip that comes with the computer, it is always available and cannot be lost due to a disk failure. Teaching Tip : If you have a BIOS chip on the motherboard in your box of demonstration hardware, show it now. 2. The Power-On Self-Test. Explain that this step is also called POST and is a diagnostic testing sequence run by the computer’s BIOS. When everything checks out as it should, the computer will sound a reassuring beep. When errors are encountered, a series of beeps are sounded and an error message appears on the screen. Class Exercise : If you are in a computer lab, ask students to boot the computers. Note if any of the systems produce an error message or fail to boot. If students encounter any error messages, ask them to make a note of the message and give it to you. Explain that you will give the note to the computer technicians to assist them in troubleshooting the problem. To create an additional learning opportunity, ask students whose computers
Chapter 5 Lecture Notes booted properly to unplug the keyboard from the machine and boot again. They will all encounter an error, 301 — Keyboard Error.
3. Loading the OS. Explain to students that once POST is successful, the BIOS finds and loads the operating system into RAM. Define CMOS (pronounced “cee-moss”) as a type of nonvolatile memory that stores the date, time, and system setup parameters. Emphasize the importance of having an emergency boot disk. Class Exercise : Have students create an emergency boot disk at home or on a computer in the lab at school. Demonstrate the process during class as a lecture, or bring diskettes so students can do this in class. For instructions on creating an emergency boot disk, refer to the Web Link below. Web Link : For students using Windows 9X or Windows Me , direct them to PCWorld.com’s article “Hardware Tips: Create Your Own Emergency Boot Disk” (www.pcworld.com/howto/article/0,aid,44202,00.asp). Class Exercise : If students are using Windows XP Professional or Windows 2000 , they must create an Emergency Repair Disk that works with the system’s built-in repair functions. To create an Emergency Repair Disk, prepare a formatted floppy disk and label it “Emergency Repair Disk,” along with the date and the name of the computer. An Emergency Repair Disk is specific to the system on which it was created. Click Start | Programs | Accessories | System Tools | Backup. The Backup utility window will appear. (If the Backup Wizard appears, click the Advanced link). Click on the Emergency Repair Disk button. When prompted to, insert the formatted floppy disk that you prepared into the floppy disk drive. Set the check box to also back up the registry. Then click on the OK button. After the Emergency Repair Disk has been written, click the OK button and remove the disk. 4. Configuring the System. Once the OS is loaded , the system loads any utility programs it might need to run peripheral devices. Explain the term plug-and-play and how it can automatically detect compatible peripherals when the power is switched on. This might be a good time to define the term registry and inform students that this very important feature of Windows will be discussed in detail. 5. Loading System Utilities. Use Figure 5.2 to explain that the next step in the booting process is loading system utilities, which include all of the configuration choices found in the Control Panel. 6. Authenticating Users. The authentication or login process is the last step in starting the computer. Explain that consumer-oriented operating systems such as Windows and Mac OS do not demand that you supply a user name and password to use the computer. However, profiles can be used for that purpose. Multiuser computer systems require that you have an account to use the system. Explain that these accounts are managed by the system administrator or SysAdmin.
B. Managing Programs
One of the functions of the operating system is the management of program execution. Help students understand the concepts of single-tasking and multitasking using an analogy.
Chapter 5 Lecture Notes Shut down the computer safely.
1. Types of User Interfaces. Refer to Figure 5.5 a-c to describe the three basic types of user interfaces: command-line , menu-driven , and GUI. Point out that most people consider GUIs easiest to use, but some experienced users like the speed of command-line interfaces. Command-line interfaces require you to type commands using keywords. The order in which the keywords are written is called the syntax. Menu-driven interfaces enable the user to avoid memorizing syntax by offering menu options to send commands to the operating system. Graphical user interfaces ( GUIs, pronounced “gooeys”) create something analogous to an actual desktop, with programs, data files, and network connections represented by small pictures called icons. 2. Default and Alternative User Interfaces. Explain that every operating system provides a default user interface but that there are programs available that act as shells over the operating system and present a different interface to the user. These are alternative user interfaces. II. EXPLORING POPULAR OPERATING SYSTEMS: A GUIDED TOUR CIYF 5. Begin this section of the lecture by explaining that all of today’s popular operating systems are strongly influenced by two very different predecessors: UNIX and Xerox PARC’s GUI interface.
A. UNIX
Explain that UNIX (pronounced “you-nix”) is popular in high-end client/server systems, in which a powerful computer called a server makes data available to users through a computer network. Web Link : For more information about UNIX and its impact on the world, visit Lucent Technologies’ Bell Labs site and read the article “The Creation of the UNIX Operating System” (www.bell-labs.com/history/unix/).
B. Xerox PARC and the First GUI
On July 1, 1970, Xerox Corporation gathered together a team of world-class researchers in information sciences and physical sciences and gave them the mission to create “the architecture of information.” This group did much of the early thinking about graphical user interfaces (GUIs) and other advanced personal computing issues. Robert Metcalfe invented Ethernet at PARC, and the GUI and mouse system used on a PARC workstation inspired Steve Jobs to build a computer with a point-and-click interface. Web Link : For more information about PARC and its impact on the information revolution, visit the PARC History Web site (www.parc.xerox.com/company/history/).
Chapter 5 Lecture Notes
C. MS-DOS
Explain that the term DOS can refer to any operating system, but it is most often used to describe MS-DOS , Microsoft’s disk operating system. MS-DOS was originally developed by Microsoft for use on the IBM Personal Computer, where it became the standard. Explain that because DOS was initially designed for the early Intel 16-bit processors, it is still a 16-bit operating system that does not support multiple users or multitasking. Point out that DOS is directly descended from UNIX and that many DOS commands are virtually identical to those in UNIX.
D. Mac OS
Point out that the Mac operating system is closely modeled after the system developed at Xerox PARC. Although Apple didn’t invent the GUI, Macintosh is credited with introducing the GUI to the rest of the world. Web Link : The Macintosh was introduced with a critically acclaimed TV commercial during the 1984 Superbowl. In fact, this commercial has been rated by TV Guide as the number-one commercial of all time. Encourage students to visit DigitalJournal.com and read the article “Apple’s Place in Home Computing” (www.digitaljournal.com/news/? articleID=3323), which includes a description of the ad.
E. Microsoft Windows
Microsoft Windows is by far the most popular operating system. Using the Windows Timeline in Figure 5.11, describe the evolution of Windows and the new features provided by each version.
1. Windows 3.X was the first GUI for the PC. Windows 3.X enabled users to take advantage of Intel’s 32-pit processor and offered protected mode, which enabled users to access unlimited amounts of memory. 2. Windows 95 was a true operating system, not just a DOS application, notable mainly as a transitional OS between the Windows 3.X (16-bit) and Windows NT (true 32-bit) operating systems. 3. Windows 98 was a more stable version of Windows 95 offering more features, including a Web browser and enhanced preemptive multitasking. 4. Windows CE is considered “Windows Lite” because it is a simplified version of Windows designed for personal digital devices. 5. Windows NT is a true 32-bit operating system and was designed to compete with UNIX and to provide a powerful option in a networked environment. 6. Windows 2000 is offered in two flavors: Professional and Server. It is considered to be an upgrade to Windows NT. 7. Windows XP is essentially the Windows NT operating environment tailored for the PC.
Chapter 5 Lecture Notes lecture. Mention that disk cleanup utilities can be used to save disk space by removing unneeded files. IV. CHAPTER REVIEW CIYF 5. Web Link : Refer students to www.prenhall.com/ciyf2004 for a review of the chapter, to answer the questions, and to complete the exercises and Web research questions. Takeaway Points Ask students to recall the objectives identified at the beginning of this lesson. Tie the initial objectives with the essential lecture points that met the objectives. Objective : List the two major components of a computer’s operating system software. System software has two major components: (1) the operating system and (2) system utilities such as backup programs. Objective : Explain why a computer isn’t useful without an operating system. Without software—the set of instructions that tells the computer what to do—a computer is just an expensive collection of wires and components. The operating system includes all the programs that are needed to enable a computer and its peripheral devices to function smoothly. Objective : List the five major functions of an operating system. An operating system works at the intersection of application software, the user, and the computer’s hardware. It manages programs, parcels out memory to applications, deals with internal messages from input and output devices, and provides a means of communicating with the user. Objective: Explain what happens when you turn on a computer. After the BIOS loads, it executes a series of tests to make sure that the computer and associated peripherals are operating correctly. Collectively, these tests are known as the power-on self-test (POST). Among the components tested are the computer’s main memory (random-access memory, or RAM), the keyboard and mouse, disk drives, and the hard disk. If the computer encounters an error, you’ll hear a beep and see an on-screen error message Objective: List the three major types of user interfaces. The three basic types of user interfaces are command-line interfaces, menu-driven interfaces, and graphical user interfaces (GUIs). GUIs are the easiest to use, but some experienced users like the speed of command-line interfaces Objective: Discuss the strengths and weaknesses of the most popular operating systems. UNIX is popular in high-end client/server systems, in which a powerful computer called a server makes data available to users through a computer network. Based on user interface ideas developed at Xerox Corporation’s research center, the Mac OS (formerly called System) introduced the GUI to personal computing. Early versions of Microsoft Windows were essentially MS-DOS applications, but Microsoft Windows 95 and 98 brought all the benefits of GUI and preemptive multitasking to PC users. Microsoft Windows NT Workstation and Windows NT Server are eating into UNIX’s market share in client/server computing. Windows 2000 is available in two versions: Windows 2000 Professional (the successor to NT Workstation) and Windows 2000 Server (the successor to NT Server). Windows XP is essentially the Windows NT operating environment
Chapter 5 Lecture Notes tailored for the PC. Linux is open-source version of UNIX that provides a great deal of power for free. It includes all of the respected features of UNIX, including multitasking, virtual memory, Internet support, multiprocessor support and a GUI. Objective: List the six system utilities that are considered essential. Essential system utilities include backup software, file managers, file finders, disk scanning programs, antivirus software, file compression utilities, and defragmentation programs. Objective: Discuss data backup procedures. A sound backup procedure begins with a full backup of an entire hard disk and continues with periodic incremental backups of just those files that have been created or altered since the last backup occurred
