Transcript operating system - PGGCG-11, Content Management Portal

A graphical user interface (GUI) is a human-computer
interface (i.e., a way for humans to interact with
computers) that uses windows, icons and menus and
which can be manipulated by a mouse (and often to a
limited extent by a keyboard as well).
GUIs stand in sharp contrast to command line
interfaces (CLIs), which use only text and are accessed
solely by a keyboard. The most familiar example of a
CLI to many people is MS-DOS. Another example is
Linux when it is used in console mode (i.e., the entire
screen shows text only).
The origin of the GUI can be traced back to Vannevar Bush,
a scientist and futurist who worked at the Massachusetts
Institute of Technology (MIT) during World War II. In his
now classic 1945 magazine article As We May Think, Bush
proposed an information administration tool, the Memex,
that would allow data to be stored on microfilm and made
easily accessible, linkable with hyperlinks and
programmable. In 1963 Ivan Sutherland, a graduate
student at MIT, developed a program for his Ph.D.
dissertation called Sketchpad, which allowed the direct
manipulation of graphic objects on a CRT screen using a
light pen. His concept included the capability to zoom in
and out on the display, the provision of memory for storing
objects and the ability to draw precision lines and corners
on the screen.
A window is a (usually) rectangular portion of the
monitor screen that can display its contents (e.g., a
program, icons, a text file or an image) seemingly
independently of the rest of the display screen. A
major feature is the ability for multiple windows to be
open simultaneously. Each window can display a
different application, or each can display different files
(e.g., text, image or spreadsheet files) that have been
opened or created with a single application.
 A major advantage of GUIs is that they make computer
operation more intuitive, and thus easier to learn and
use.
 Adding to this intuitiveness of operation is the fact
that GUIs generally provide users with immediate,
visual feedback about the effect of each action.
 In addition, GUIs allow users to take full advantage of
the powerful multitasking (the ability for multiple
programs and/or multiple instances of single programs
to run simultaneously) capabilities of modern
operating systems by allowing such multiple programs
and/or instances to be displayed simultaneously.
An operating system or OS, is a software program
that enables the computer hardware to communicate
and operate with the computer software. Without a
computer operating system, a computer and software
programs would be useless. An operating system is a
program designed to run other programs on a
computer. A computer’s operating system is its most
important program. It is considered the backbone of a
computer, managing both software and hardware
resources.
 Multi-user : Allows two or more users to run
programs at the same time. Some operating systems
permit hundreds or even thousands of concurrent
users.
 Multiprocessing : Supports running a program on
more than one CPU.
 Multithreading : Allows different parts of a single
program to run concurrently.
 Real time: Responds to input instantly. Generalpurpose operating systems, such as DOS and UNIX,
are not real-time.
When a single program is allowed to run at a time,
the system is grouped under a single-tasking
system, while in case the operating system allows
the execution of multiple tasks at one time, it is
classified as a multi-tasking operating system.
A real-time operating system is a multitasking
operating system that aims at executing real-time
applications. Real-time operating systems often use
specialized scheduling algorithms so that they can
achieve a deterministic nature of behavior. The main
objective of real-time operating systems is their quick
and predictable response to events.
A multi-user operating system allows multiple users to
access a computer system concurrently. Time-sharing
system can be classified as multi-user systems as they
enable a multiple user access to a computer through
the sharing of time. Single-user operating systems, as
opposed to a multi-user operating system, are usable
by a single user at a time. Being able to have multiple
accounts on a Windows operating system does not
make it a multi-user system.
 Multi-user - A multi-user operating system allows for multiple
users to use the same computer at the same time and different
times. See the multi-user definition for a complete definition for
a complete definition. Below are some examples of multi-user
operating systems.
Linux
Unix
Windows 2000
 Multiprocessing - An operating system capable of supporting
and utilizing more than one computer processor. Below are some
examples of multiprocessing operating systems.
Linux
Unix
Windows 2000
 Multitasking - An operating system that is capable of
allowing multiple software processes to run at the same
time. Below are some examples of multitasking operating
systems.
Unix
Windows 2000
 Multithreading - Operating systems that allow different
parts of a software program to run concurrently. Operating
systems that would fall into this category are:
Linux
Unix
Windows 2000
Thank You..
Chhavi Mahajan