It is essential to
maintain a system (like democracy, Kingdom or communism) to operate a state.
Similarly, it is (a system) also essential for a computer. This type of
software is known as operating system which operates computer. It is very
important software and it falls under the category of system software.
An operating system is
a software component that acts as the core of a computer system. It performs
various functions and is essentially the interface that connects your computer
and its supported components.
According to
Wikipedia An operating system (OS)
is software, consisting of programs and data, that runs on
computers and manages computer hardware resources[1] and provides
common services for efficient execution of various application software.
According to Pradeep
Kumar Sinha, “Operating system is an integrated set of programs that
controls the resources of a computer system and provides its users with an
interface or virtual machine that is more convenient to use than the bare
machine.”
Functions
Of Operating System
Today most operating systems perform the following important functions: 1.
Processor management, that is, assignment of processor to different tasks being
performed by the computer system. 2. Memory management, that is, allocation of
main memory and other storage areas to the system programmes as well as user
programmes and data. 3. Input/output management, that is, co-ordination and
assignment of the different output and input device while one or more
programmes are being executed. 4. File management, that is, the storage of file
of various storage devices to another. It also allows all files to be easily
changed and modified through the use of text editors or some other files
manipulation routines. 5. Establishment and enforcement of a priority
system. That is, it determines and maintains the order in which jobs are to be
executed in the computer system. 6. Automatic transition from job to job as
directed by special control statements. 7. Interpretation of commands and
instructions. 8. Coordination and assignment of compilers, assemblers,
utility programs, and other software to the various user of the computer
system. 9. Facilities easy communication between the computer system and the
computer operator (human). It also establishes data security and integrity.
10. The security
module of an operating system protects the resources and information of a
computer system against destruction and unauthorized access.
Introduce with some
popular Operating System
MS-DOS - a
single-user, single-tasking operating system that uses a command line (i.e.,
text only) user interface. It was launched by Microsoft in 1981 and used
on the first personal computers, which were introduced by IBM in the same year.
In spite of its very small size and relative simplicity, MS-DOS is one of the
most successful operating systems that have been developed to date.
Advantages: DOS has many advantages. The advantages will
be the reasons for learning DOS. DOS is the most popular microcomputer
operating system for IBM computers and compatibles ever sold worldwide. It runs
thousands of applications, and is easy to use. DOS is easy for
novices to use, and many publications and books are available for the operating
system. DOS runs on low- priced IBM computers and compatibles. DOS
does not require an expensive computer system while some others still do.
Disadvantages: DOS has some drawbacks, but there is no doubt
that we will continue to see DOS used in the 1990s. It will then slowly be
replaced as the dominant operating system. The hardware has evolved in
significant ways. New microcomputers have more capacity and faster electronics
than the old IBM PC and compatibles. This makes DOS an old operating system.
Microsoft
Windows - the successors to the very popular MS-DOS, it was announced in
1983, and the first version, Windows 1.0, was finally released in 1985.
Microsoft Windows encompasses two groups of operating systems (i.e., Windows
95/98/ME/CE and Windows NT/2000/XP) which resemble each other superficially and
share compatibility with many of the same application programs but which have
very different internal structures.
Windows 95
Windows 95 upgrades
its earlier versions (Windows 3.x) in many ways. It has a new 3-D interface. It
is mostly a 32- bit system although it has 16-bit components included for
compatibility with Windows 3.x. Windows 95 does not need to have a separate
DOS. It integrates all DOS services. A Windows 95 system runs in protected
mode. This means that it speeds up the processors and provides more safety.
Windows 95 serves two purposes: It will move developers to the Win32 API and
will ease the transition for users whose hardware is not yet ready to handle
the demands of Windows NT. Windows 95 offers better preemptive
multitasking. Although for most things, cooperative multitasking is
good. However, if users want to do several things simultaneously, they are
going to find that preemptive multitasking provides smoother operation and
better speed.
Advantages: This operating system provides compatibility
with existing Windows and DOS programs. It also offers compatibility with
existing Windows and DOS device drivers. It works as in standalone computer and
in networked environment for both desktop and mobile users. It supports Windows
for Workgroups, Novell and UNIX-style networks. It is easier to learn and
use, gives users better performance, has more capacity, integrates applications
better, connects better, and crashes less than its predecessor, Windows 3.x.
Disadvantages: Windows 95 still has limits from 16-bit
components retained for backward compatibility with 16-bit application. It does
not give much benefit to the 16-bit applications. To get benefits from Windows
95, users must upgrade their applications to 32-bit versions that support OLE
and can interact directly with Windows 95's shell. It will cost users
significant.
Windows XP
Windows XP is an operating system that
was produced by Microsoft for use onpersonal computers, including
home and business desktops, laptops, and media centers. It was first
released to computer manufacturers on August 24, 2001, and is the most popular
version of Windows, based on installed user base. The name "XP"
is short for "eXPerience.
Windows XP was the
successor to both Windows 2000 and Windows Me, and was the first
consumer-oriented operating system produced by Microsoft to be built on
the Windows NT kernel and architecture. Windows XP was released
for retail sale on October 25, 2001, and over 400 million copies were in use in
January 2006, according to an estimate in that month by
an IDC analyst. It was succeeded byWindows Vista, which was
released to volume license customers on November 8, 2006, and worldwide to the
general public on January 30, 2007. Direct OEM and retail sales of
Windows XP ceased on June 30, 2008. Microsoft continued to sell Windows XP
through their System Builders (smaller OEMs who sell assembled computers)
program until January 31, 2009.XP may continue to be available as these sources
run through their inventory or by purchasing Windows 7 Ultimate, Windows 7 Pro,
Windows Vista Ultimate or Windows Vista Business, and thendowngrading to
Windows XP. Windows XP was eventually released for two additional
architectures, Windows XP 64-bit
Edition for IA-64 (Itanium) processors and Windows XP
Professional x64 Edition for x86-64. There is also Windows XP Embedded,
a component version of the Windows XP Professional, and editions for specific
markets such as Windows XP Starter Edition. By mid 2009, a manufacturer
revealed the first Windows XP powered cellular telephone. The NT-based
versions of Windows, which are programmed in C, C++, andassembly,[11] are
known for their improved stability and efficiency over the 9xversions
of Microsoft Windows.
Windows NT (New
Technology)
Window NT is a
platform for 32-bit Windows applications. This is a powerful and one of the
most advanced operating systems available today. Windows NT was originally
designed with big-system features. Beginning with version 3.5, Microsoft began
repositioning Windows NT as a workstation and server operating system. It also
has a sophisticated multiuser security system, so Windows NT performs
excellently as a disk server. NT has support for network services useful to
applications like client/server database engines. Still, all the features of
Windows NT are suitable for use in demanding applications of desktop users.
Advantages: Windows NT allows users to run all
applications, including Windows applications, from the command line. It has
better speed. Windows NT does not have arbitrary resource limits. Computer
system reliability is improved by the result of this. It has the familiar Windows
3.x-style user interface, so users do not need to spend much time for learning.
NT has a preemptive multitasking capability, and the users can multitask
applications within their own memory spaces. It has much more reliable
networking capability than that provided by Windows 3.x or Windows 95.
Disadvantages: Windows NT is a platform for 32-bit Windows
applications. 32- bit applications are not widely available yet. Still, 16-bit
applications are prevailing in the software market. This operating system requires
much resource. Windows NT workstation requires 12MB of memory when run on Intel
486/pentium computers (It runs in 8MB, but Microsoft recommends 12MB for NT to
run adequately). Windows NT server requires 16MB. Windows NT system that is run
on an RISC workstation also demands 16MB of memory. The NT requires at least
70MB of hard disk space only for the operating system. After all, this
operating system requires too much for normal microcomputer users
UNIX
UNIX was originally
developed in 1969 by K. Thompson, R. Canaday and D. Ritchie for minicomputers
in the Bell Laboratories in the USA owned and run by AT& T. By the
mid-1970s, UNIX had been introduced to University of California at Berkeley by
Thompson, then widespread into an academic world. Most computer science
departments of universities have been used UNIX. UNIX initially became popular
in industry because for many years AT& T licensed the system to
universities for a nominal fee. The effect of this was that UNIX was carried by
recent computer science and engineering graduates to their new places of
employment. Rapid commercialization of UNIX followed on from this. This rapid
commercialization caused the lack of standards. Many hardware and software
vendors developed their own versions. After UNIX was widespread, it had been
used by scientists and engineers. It is because of its scientific and technical
orientation. It is less well known with business people. All that, however, is
probably about to change. The reason is that with the arrival of very powerful
microcomputers using the newer chips such as pentium and pentium-pro chips,
UNIX has become a major player in the microcomputer world. The difficulty of
learning is also about to change because of the graphical user interface.
This is a multiuser,
multitasking operating system that runs on many different computer systems from
microcomputer to mainframe, because UNIX is written in C programming language,
which is a language designed for system-level programming. UNIX is consisted of
a kernel, the file system, the user interface. The kernel is the heart of the
operating system. The file system has a hierarchical directory method for
organizing files on the disk and the shell.
Advantages: UNIX is the portable operating system
that can be used with many different computers from mainframe to microcomputer.
The other operating systems such as DOS, Windows, Mac operating system, and
OS/2 cannot be used for other systems. One of many strong features of UNIX is
multitasking. UNIX allows users to run multiple programs simultaneously. UNIX
also shares it among multiple users. UNIX is not restrained by the computer
systems such as conventional memory as the DOS and OS/2 systems are. It can
accomplish many operations that were formerly performed on minicomputers or
mainframes. It is important, because industry can achieve the performance and
benefits of large computers from microcomputers by using UNIX. Networking is
another strong feature of a UNIX operating system. UNIX can be connected
through several different kinds of equipment. It can share files among them.
Disadvantages: Although UNIX can do many things, it can be
difficult for novice microcomputer users to understand. This is a reason it has
had a limited impact to date. UNIX was a minicomputer operating system used by
programmers and computer science professionals some time before the rise of the
microcomputer. This means that it has certain qualities making it useful to
programmers - many supporting utility programs and documentation, for instance.
Some of its features make it difficult for end users. Limited application
programs are another disadvantage for UNIX. UNIX off-the-shelf programs for
microcomputers are limited. However, this situation is going to change, because
many software vendors are rewriting DOS and Windows applications for UNIX.
There is not a standard for UNIX. This may be the biggest problem for the
popularity of UNIX. The principal microcomputer versions are the AT& T UNIX
System V, the UC Berkeley UNIX, and Xenix developed by Microsoft for a
microcomputer version. AIX from IBM, Solaris, and Linux are other variants of
UNIX. An application program written for one version of UNIX may not run on
other versions. There is also not a standard GUI for many UNIXs. There were
several attempts to combine the Sun, AT& T, and U.C. Berkeley versions of
UNIX to produce a standard graphical user interface. The one was Open Look
(Sun/Open Windows) by Sun, AT& T and Berkeley. Another graphical user
interface was an OSF/Motif by the Open Software Foundation (OSF). OSF/Motif is
now in s
Linux
A high
performance, yet completely free, Unix-like operating system launched
by Linus Torvalds in 1991. GNU/Linux, as it is also called
(because it makes extensive use of utilities and other software developed by the
GNU project) is suitable for use on a wide range of platforms and is
compatible with both 32 bit and 64 bit processors. More than
200 distributions (i.e., versions) of Linux have been introduced,
among the most popular of which are Red Hat, SuSE, Mandrake, Debian and Ubuntu.
Although its overall market share is still small, Linux is the most rapidly
growing of any major operating system. Linux is a great variant of UNIX. It has
most of the features and, in some cases, better features of UNIX. Furthermore,
it runs on lower end machines - 386- class system or higher with 8MB of memory.
It requires only as small as 20MB of hard disk space to install it. It requires
a CD-ROM drive.
MINIX - a small,
open source UNIX clone that was first released in January 1987. It
was written for use in computer scienceeducation by Professor Andrew S.
Tanenbaum of Vrije Universiteit in Amsterdam, and it is now best known for its
role in inspiring Linus Torvalds to develop Linux.
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