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.

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

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

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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
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.

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.

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.

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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.

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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

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Windows OS (History)

• 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.

13
Windows OS (History)

• Windows 98, Me, 2000, and XP take us into recent
  history.
• Integrated Internet application and features
• Integrated multimedia support

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)

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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

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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.

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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.

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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.

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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
  dont have to wait.

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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.

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Plug and Play

• Allows for easy installation of new hardware.
• The OS recognizes that youve 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 vendors Web site.

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
  doesnt 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.

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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.

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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

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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

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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.

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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

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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.

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Disk Defragmenter

• A single file that cant 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.

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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.

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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.

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Types of Operating Systems

• 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

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Controlling a Network

• A Network OS (NOS) is an OS designed specifically
  for serverscomputers 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.

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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.

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.

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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.

37
Embedded OS

• Handheld computers require an OS to manage their
  functions as well.
• Because of their small size, they dont 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

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.

39
The End

• Make sure you carefully read this chapter after
  going through this presentation on your own and
  in lecture.
• Dont 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 youve
  read.