Operating Systems

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Operating Systems

• An Introduction

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What Does An Operating System Do?

• Manages the hardware and software resources of
  the system. In a desktop computer, these
  resources include such things as the processor,
  memory, disk space, etc.
• Provides a stable, consistent way for
  applications to deal with the hardware without
  having to know all the details of the hardware.

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Operating systems
Application
The operating system acts a a shell around the
hardware. The applications software need an
operating system to work, and users need the
applications software to interact with the
hardware via the operating system.
Operating system
User
Hardware
Application
Application
User
User
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Popular Operating Systems

• UNIX
• Linux
• Windows 2000
• Windows XP
• Windows 2003
• Macintosh OS X

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What Kinds Are There?

• Real-time operating system (RTOS) - Real-time
  operating systems are used to control machinery,
  scientific instruments and industrial systems. An
  RTOS typically has very little user-interface
  capability, and no end-user utilities.
• Single-user, single task - Operating system
  designed to manage the computer so that one user
  can effectively do one thing at a time. The Palm
  OS for Palm handheld computers is a good example
  of a modern single-user, single-task operating
  system.

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What Kinds Are There?

• Single-user, multi-tasking - Type of operating
  system most people use on their desktop and
  laptop computers today.
• Multi-user - A multi-user operating system allows
  many different users to take advantage of the
  computer's resources simultaneously. The
  operating system must make sure that the
  requirements of the various users are balanced,
  and that each of the programs they are using has
  sufficient and separate resources

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Networked is not Multi-user

• Most modern operating systems can exist in a
  network.
• A user on one computer on the network can connect
  to shared directory/folder on another computer.
• However this does not necessarily make the
  operating system multi-user.
• A user connected to a shared resource on another
  computer is not actually using any of that
  computers CPU or memory.

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Networked is not Multi-user

• Using this yardstick UNIX/Linux is considered
  multi-user.
• When a user on another computer connects to a
  UNIX computer using telnet or X-Windows then that
  user is actually using CPU and memory resources
  on the UNIX computer.
• UNIX/Linux can also function as a networked
  computer when running services such as NFS or
  Samba.

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Networked is not Multi-user

• Like UNIX, Windows can function as a networked
  computer.
• When the File and Printer Sharing Service is
  enabled, users on other computers on the network
  can connect to shared folders and printers.
• Users connected to those shared resources are not
  actually utilising the CPU or memory of the
  computer housing the shares.

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Networked is not Multi-user

• Here are some features of Windows that may
  qualify it as a multi-user OS.
• Windows XP has a switch user function, a second
  user can log onto Windows XP while leaving most
  of the first users programs running.
• Windows 2000/2003 Server has a telnet server,
  similar to the telnet service in UNIX.
• Windows 2000/2003 Server can function as a
  terminal services server, users connected as
  terminal services clients will actually be using
  the CPU and memory of the Windows server.

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History of UNIX

• Late 1960s UNIX designed by Ken Thomson of ATT
  Bell Laboratories.
• 1973 - UNIX rewritten in the C-language by Dennis
  Ritchie, and distributed for a small fee to
  universities.
• 1976 - First commercial version, UNIX Version 6,
  developed by ATT.
• 1980 - Berkeley Software Distribution (BSD) UNIX
  produced.

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History of LINUX

• 1985 - Richard Stallman releases his GNU (aka
  "GNU is Not Unix") Manifesto thus starting the
  open source revolution.
• 1987 - Andrew Tannenbaum creates MINIX, a small,
  highly portable Unix clone for educational/academi
  c purposes.
• Sep 1991 Linus Torvalds releases Linux version
  0.01's source code. It isnt an independent OS
  due to the fact that it still needs MINIX to
  compile.

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History of LINUX

• Dec 1991 Linux v0.11 released as a standalone
  operating system with floppy disk support.
• 1993 Slackware Linux v1.00 released by Patrick
  Volkerding.
• 1994 RedHat Linux v1.00 released.
• 1996 Debian Linux v1.00 released.

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Red Hat Linux Screen Shot
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History of Windows

• 1975 Microsoft founded by Bill Gates and Paul
  Allen.
• 1981 MS-DOS v1.0 released.
• 1985 Windows v1.0 released as a GUI running on
  top of MS-DOS.
• 1992 Windows for Workgroups v3.11 released with
  integrated network capability.
• 1992 NT 3.1 released, MS-DOS independent.

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History of Windows

• 1994 NT 3.5 released, 32-bit processing.
• 1995 Windows 95 released as an upgrade to
  Windows 3.11.
• 1998 Windows 98 released.
• 2000 Windows 2000 released.
• 2001 Windows XP released, 64-bit version
  available.
• 2003 Windows Server 2003 released.

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What is Macintosh OS X

• Mac OS X is a super-modern operating system that
  combines the power and stability of UNIX with the
  legendary elegance of the Macintosh.Mac OS X
  features a stunning new user interface called
  Aqua, making work and play on the Mac even more
  intuitive for new users, while providing
  powerful, customizable tools for professionals.
  At the foundation of Mac OS X lies an
  industrial-strength UNIX-based core operating
  system that delivers unprecedented stability and
  performance.
• Quote from http//www.apple.com/macosx/techspecs

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Macintosh OS X Screen Shot