Lecture 2

Operating System
General
DIT Part 1
Lecture 2

Role of OS In Computing Environment
• An operating system is an interface between
hardware and user.
• An OS is responsible for the management and
coordination of activities and the sharing of the
resources of the computer.
• The operating system acts as a host for
computing applications run on the machine.
• As a host, one of the purposes of an operating
system is to handle the details of the operation of
the hardware.
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• This relieves application programs from having
to manage these details and makes it easier to
write applications.
• Almost all computers including handheld
computers, desktop computers,
supercomputers, video game consoles as well
as some robots, domestic appliances, and
portable media players use an operating
system of some type.

Cloud Computing & OS

• The operating system of a large computer
system has even more work to do.
• Such operating systems monitor different
programs and users, making sure everything
runs smoothly, without interference, despite
the fact that numerous devices and programs
are used simultaneously.
• An operating system also has a vital role to
play in security.

• Its job includes preventing unauthorized users
from accessing the computer system.
• There are multiuser, multiprocessing,
multitasking, multithreading, and real-time
operating systems.
• A multiuser operating system enables multiple
users to run programs simultaneously. This
type of operating system may be used for just
a few people or hundreds of them.

• In fact, there are some operating systems that
are used to allow thousands of people to run
programs at the same time.
• A multiprocessing operating system allows a
program to run on more than one central
processing unit (CPU) at a time.
• This can come in very handy in some work
environments, at schools, and even for some
home-computing situations.

• Multitasking operating systems work a little
differently; they make it possible to run more
than one program at a time.
• Multithreading operating systems are even
more different, allowing varied parts of one
program to be used simultaneously.
• Real-time operating systems are designed to
allow computers to process and respond to
input instantly.

• Usually, general-purpose operating systems,
such as disk operating system(DOS), are not
considered real time, as they may require
seconds or minutes to respond to input.
• Real-time operating systems are typically used
when computers must react to the consistent
input of information without delay.
• For example, real-time operating systems may
be used in navigation.

• Today’s operating systems tend to have
graphical user interfaces (GUIs) that employ
pointing devices for input.
• A mouse is an example of such a pointing
device, as is a stylus.
• Commonly used operating systems for IBM-
compatible personal computers include
Microsoft Windows, Linux, and Unix
variations.

• For Macintosh computers, Mac OS X, Linux,
BSD, and some Windows variants are
commonly used.

Computing Environments
• Traditional computing.
• Web-Based Computing.
• Embedded Computing.

Traditional Computing
• Advancing technologies and falling prices
rapidly re changing what used to be
“traditional computing”.
• Not only are “enterprise” level functions being
pushed down to the PC level, but new
functions are being directly implemented in
the PC/micro-computers

Traditional Computing

Web-Based Computing
• Applications reside on Web servers, rather
than on end-users' workstations.
• These workstations, or appliances are
connected to secure servers in order to use
applications via web browsers.

Web-Based Computing

Embedded Computing
• Most prevalent form of computers in
existence: In automobiles, VCR’s, microwave
ovens.
• They do specific tasks, and associated systems
are primitive.

Embedded Computing

Lecture 2

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Lecture 2