Topics of Discussion

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Topics of Discussion

• System software.
• Operating systems.

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System Software vs Application Software

• System software
• Consists of programs to control the operations of
  computer hardware e.g. Windows
• Application Software
• Consists of programs that tell a computer how to
  produce information e.g. word processor.

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System Software

• Serves as an interface between you (the user),
  your application software, and your computers
  hardware.
• Two types of system software
• Operating system
• Utility programs

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Operating System (OS)

• Software that controls the computers use of its
  hardware resources.
• Co-ordinates the activities within the computer.
• Interacts with application software to carry out
  application tasks such as printing, saving, etc.

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Operating System (OS)

• Different sizes/types of computers use different
  operating systems.
• Mainframe computers do not use the same OS as the
  a desktop computer.
• Various OS are not compatible with each other.

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Operating System (OS)

• OS that a computer uses sometimes is called the
  software platform or platform
• Application software that runs on one platform
  may not run on the other platform.
• A cross-platform application runs on multiple OS

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Operating System Services

• External
• Helps users start programs, manage stored data,
  and maintain security.
• Also helps you find, rename, and delete documents
  and other data stored.
• Internal
• Not under you control but instead controlled by
  the operating system itself.
• Controls input/output, allocates system
  resources, managers the storage space for
  programs and data, and detects equipment failure.

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Memory Management

• OS manages the allocation of data and
  instructions in the memory area.
• A buffer is an area of memory in which data is
  placed while waiting to be transferred to and
  from an input or output device.
• Virtual memory storage space on the hard disk.
  This area is called a swap file. Amount of data
  and instructions exchanged is called a page.
• When OS spend too much time paging it is said to
  be thrashing.

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Starting the computer

• Booting - process of starting or restarting the
  computer.
• Cold boot turning on a computer after it has
  been powered off completely.
• Warm boot process of restarting a computer that
  is already powered on.

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Starting the computer

• Each time one boot a computer, the kernel and
  other frequently used operating system
  instructions are loaded or copied from the hard
  disk (storage) to the computers memory.

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Kernel

• Kernel the core of the OS which does all the
  functions of the OS-
• Manages memory and devises
• Maintains the systems clock
• Starts applications
• Assigns computer resources.

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Managing Programs

• Single user/tasking one user running the
  program
• Multitasking one user working on more than one
  applications at the same time
• Multi-user more than one users running a
  program simultaneously
• Multiprocessing more than one processors
  running a program (fault-tolerant)

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Spooling Print Jobs

• Document you are printing is called a print job.
• With spooling the print jobs are placed in a
  buffer instead of being sent to the printer.
• Multiple print jobs are queued in the buffer.
• Program that managers print jobs is called a
  print spooler.

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Administering Security

• Users are allowed to log on with a user name and
  password.
• User name is a unique combination of characters
  that identifies one specific user.
• Password associated with user name to prevent
  unauthorized users from accessing the computers
  resources.

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Password Guide

• Make password at least 8 characters.
• Join two words.
• Choose words from other languages.
• Mix letters and numbers together.
• Use a nonsense word.

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Password Guide
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Popular OS

• DOS
• Windows
• Mac OS
• UNIX

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DOS

• Disk Operating System.
• Command-line OS.
• Have to remember codes or commands to use it
  efficiently.
• Replaced by Windows.

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Windows

• Versions Windows 3.1, 95, 98, NT.
• Graphical User Interface (GUI).
• Use icons to represent objects.

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Mac OS

• Apple computers.

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UNIX

• Command-line interface, but can purchase add-on
  software to make it GUI.
• Multi-user OS in which many people can run
  programs on a single machine.
• Popular with companies that provide information
  on the Internet.

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REFERENCE

• Shelly Cashman Series, Discovering Computers
  Concepts for a Digital World 2002, Chapter 8