Operating System

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Operating System

• COMP 101
• Spring Semester, 2006
• (Last Modified 2006/01/27)

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Functions of an OS

• Used in all general purpose (stored-program)
  computers
• Accepts commands from a user
• Makes the relevant components act in response to
  the commands
• Schedules the activities for best performance

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Inside the PC tower

• Central processing unit (CPU)
• Memory (RAM)
• Hard disk
• Floppy disk drive
• CD-ROM drive
• Mother board

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Peripheral devices

• Keyboard
• Mouse
• Monitor
• Printer
• Etc.

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The operating system

• A large piece of software that makes the various
  hardware components work together to solve
  problems for the user
• A flexible piece of software that can accommodate
  new components and applications

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Nature of an OS

• Tied to certain base hardware platforms
• Apple OS 9/OS X
• PC Microsoft Windows/GNU Linux
• Sun Solaris
• PDA Palm OS/PocketPC
• Contains more functions than a user will ever
  learn/use ?

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An operating system
Applications
Operating System
Device Drivers
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File management

• File a string of bytes containing data or
  instructions
• Folder a collection of files and folders for
  easy reference
• Directory a list of items inside a folder for
  use by the operating system
• Disk a physical device to hold files, folders,
  and directories

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Disk maintenance

• Format clean out disk contents and repair
  damaged sectors
• Defragment store long files in consecutive
  sectors for more efficient retrieval

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File backups

• All operating systems crash from time to time
• Both software and hardware crashes may damage the
  file structure
• Virus attacks often cause file damage
• Files containing important information should be
  copied to removable media (e.g., flash memory
  sticks, writable CDs) on regular basis
• Large files may be compressed first before
  copying

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Graphical user interface (GUI) with the OS

• Move mouse pointer to desired item
• Single click to select
• Double click to launch application
• Click and drag to move item
• Right click for properties

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Command line interface (CLI) with the OS
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CLI vs. GUI
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Multi-tasking

• Performing several applications at the same
  time
• Making better use of the CPU

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Disk tracks and sectors