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Operating Systems
An Introduction
What Does An Operating System Do?
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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.
Operating systems
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
Hardware
Application
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User
Application
Application
User
User
Popular Operating Systems
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UNIX
Linux
Windows 2000
Windows XP
Windows 2003
Macintosh OS X
What Kinds Are There?
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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.
What Kinds Are There?
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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
Networked is not Multi-user
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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 computer’s
CPU or memory.
Networked is not Multi-user
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Using this yardstick UNIX/Linux is considered multiuser.
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.
Networked is not Multi-user
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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.
Networked is not Multi-user
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Here are some features of Windows that may qualify
it as a multi-user OS.
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Windows XP has a switch user function, a second user can
log onto Windows XP while leaving most of the first user’s
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.
History of UNIX
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Late 1960s – UNIX designed by Ken Thomson of
AT&T 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 AT&T.
1980 - Berkeley Software Distribution (BSD) UNIX
produced.
History of LINUX
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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/academic
purposes.
Sep 1991 – Linus Torvalds releases Linux version
0.01's source code. It isn’t an independent OS due to
the fact that it still needs MINIX to compile.
History of LINUX
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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.
Red Hat Linux Screen Shot
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History of Windows
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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.
History of Windows
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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.
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 industrialstrength 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
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