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Operating systems

The most important program that runs on a computer. Every general-purpose computer must have an operating system to run other programs. Operating systems perform basic tasks, such as recognizing input from the keyboard, sending output to the display screen, keeping track of files and directories on the disk, and controlling peripheral devices such as disk drives and printers.

For large systems, the operating system has even greater responsibilities and powers. It is like a traffic cop -- it makes sure that different program and users running at the same time do not interfere with each other. The operating system is also responsible for security, ensuring that unauthorized users do not access the system. The basic purposes and functions of operating system are as follows:

Operating system types:

As computers have progressed and developed so have the types of operating systems. Below is a basic list of the different types of operating systems and a few examples of operating systems that fall into each of the categories. Many computer operating systems will fall into more than one of the below categories.


Short for Graphical User Interface, a GUI Operating System contains graphics and icons and is commonly navigated by using a computer mouse. See our GUI dictionary definition for a complete definition. Below are some examples of GUI Operating Systems.


A multi-user operating system allows for multiple users to use the same computer at the same time and/or different times..


Support running a program on more than one CPU.


An operating system that is capable of allowing multiple software processes to run at the same time.


Operating systems that allow different parts of software program to run concurrently.


Microsoft Windows:

Microsoft windows is a series of programs that are designed by MICROSOFT Corporation. Windows provides graphical display which makes computer system user friendly. It also organizes information that can be easily accessed. Microsoft introduced the operating system in 1985 and it has continued to be widely used without any competition. The operating system utilizes icons and tools that simplify the complex operations performed by computer.

From the family of operating systems Windows dominates the personal computer world, about 90% running on of all personal computers. It has become a standard for individual users in almost every corporation as well as in homes also. The first version was introduced to homes and business PC users. It works with most kinds of software and hardware. Microsoft Windows is the best GUI available and I used widely. A number of versions have been released by the Microsoft Windows and all have been used largely. Some of the versions of Microsoft Windows are Windows 3.0, Windows 3.1, Windows 95, Windows 98, Windows Me, Windows XP, Windows 2000, Windows Vista, Windows CE, Windows 7, Windows server 2003 and Windows NT and so on. All of these versions were having new features and new characteristics. The Microsoft Windows is having two parallel routes which are making it more popular. It means that it is not only being used in the professional applications but is also largely being used by the home users. It is also known as the simplest operating system which can be easily handled by the user. All the versions of the Microsoft Windows are having least functionally to be performed by the user but greater support of multimedia, networking and security.

Features of Microsoft Windows:


Windows brings a more responsive and sprightly feel and Microsoft has spent a lot of time and effort getting the Start Menu response just right. Microsoft has also recognized the need for improved desktop responsiveness, which gives the impression that the computer is responding to the user and that they are in control. It also gives faster boot times.


Many programs that individuals and companies used on DOS did not work immediately and required updates, but with Windows almost all applications that work on should still run.

Search and Organization:

One of the best things about Windows is the improved search tool, through which users are able to find what you need quickly and easily. In Windows Microsoft introduced the concept of Libraries. The various Libraries, such as Documents and Pictures, will watch multiple locations which you can add yourself, so you don't have to keep everything in one place.

Ease of Access Center:

Provides a centralized location where you can adjust accessibility settings and manage accessibility programs.

Speech Recognition:

Enables you to interact with your computer using only your voice while maintaining, or even increasing, your productivity.


A text-to-speech program that reads aloud on-screen text and describes some events (such as error messages) that happen while you're using the computer.

On-Screen Keyboard:

A visual, on-screen keyboard with all the standard keys that you can use instead of a physical keyboard. On-Screen Keyboard also lets you type using an alternative input device.

Keyboard shortcuts:

Use keyboard shortcuts as an alternative to the mouse. Keyboard shortcuts can be found in the menus of programs, or, if a letter is underlined on a menu, it usually means that pressing the ALT key in combination with the underlined key has the same effect as clicking that menu item.


Get information via animations and video that some programs use to indicate that activity is happening on your computer.

Task bar/ Start Menu:

taskbar icons are larger and items are grouped together and are not labeled with clumsy text. If you have multiple Word documents or Windows Explorer windows open then you'll see a stack appear on the task bar. You can close each document or Window down from the thumbnail directly or click on it to bring it to the front. In the Start menu, a small arrow to the right of applications such as Word expands to give a list of recent documents and any can be pinned so you can keep one permanently on the list.

Graphical User Interface:

All the versions of Microsoft Windows are having the best GUI. This makes it easier to use as all the activities are performed by clicking the icons.

Multimedia Support:

The multimedia applications are highly supported by this operating system.

Automatic updates:

Automatic updates reduce the chance of home workers not installing critical security patches, because the process is automated by default. Behind the scenes, XP regularly connects to the Microsoft Web site and looks for needed patches. If it finds any, it automatically downloads them (still behind the scenes). Then, once the patches are downloaded, a screen pops up saying the latest patches are ready and asks the user if he or she is ready to install them. Automatic updates

Usage of Microsoft Windows

Microsoft Windows is the most widely used operating system all over the world. The usage of this operating system is very broad and in the following we have given the most common usages of this operating system:


Solaris is a UNIX-based operating system introduced by Sun Microsystems in 1992 as the successor to SunOS. Solaris is known for its scalability, especially on SPARC systems, and for originating many innovative features such as DTrace and ZFS. Solaris supports SPARC-based and x86-based workstations and servers from Sun and other vendors, with efforts underway to port to additional platforms.

Solaris is certified against the Single Unix Specification. Although it was historically developed as proprietary software, it is supported on systems manufactured by all major server vendors, and the majority of its codebase is now open source software via the OpenSolaris project.

In 1987, AT&T and Sun announced that they were collaborating on a project to merge the most popular Unix variants on the market at that time: BSD, System V, and Xenix. This would become Unix System V Release 4 (SVR4).

On September 4, 1991, Sun announced that it would replace its existing BSD-derived Unix, SunOS 4, with one based on SVR4. This was identified internally as SunOS 5, but a new marketing name was introduced at the same time: Solaris 2.While SunOS 4.1.x micro releases were retroactively named Solaris 1 by Sun, the Solaris name is almost exclusively used to refer to the SVR4-derived SunOS 5.0 and later. The justification for this new "overbrand" was that it encompassed not only SunOS, but also the Open Windows graphical user interface and Open Network Computing (ONC) functionality. The SunOS minor version is included in the Solaris release number; for example, Solaris 2.4 incorporated SunOS 5.4. After Solaris 2.6, Sun dropped the "2." from the number, so Solaris 7 incorporates SunOS 5.7, and the latest release SunOS 5.10 forms the core of Solaris 10.

Features of Solaris:


Solaris 10 includes some of the world's most advanced security features, such as Process and User Rights Management, Trusted Extensions for Mandatory Access Control, the Cryptographic Framework and Secure By Default Networking that allow you to safely deliver new solutions, consolidate with security and protect mission-critical data.


The Solaris 10 release gives you observability into your system with tools such as Solaris Dynamic Tracing (DTrace), which enables real-time application debugging and optimization.


Solaris 10 delivers indisputable performance advantages for database, Web, and Java technology-based services, as well as massive scalability, shattering world records by delivering unbeatable price/performance advantages.

Platform Choice

Solaris 10 is fully supported on more than 1200 SPARC-based and x64/x86-based systems from top manufacturers, including systems from Sun, Dell, HP, and IBM.


With its optimized network stack and support for today's advanced network computing protocols, Solaris 10 delivers high-performance networking to most applications without modification.


The Solaris 10 OS includes industry-first virtualization features such as Solaris Containers, which let you consolidate, isolate, and protect thousands of applications on a single server.

Data Management

Solaris 10 offers dramatic advances in file system and volume management by delivering virtually unlimited capacity and near-zero administration.


New Solaris 10 features, such as Predictive Self Healing, support automatic diagnosis and recovery from hardware and application faults, maximizing system uptime.


Understanding that businesses today rely on a mix of technologies from a variety of vendors, Solaris 10 provides tools to enable seamless interoperability with hundreds of heterogeneous hardware and software platforms.

Support & Services

Offering a broad portfolio of world-class services, Sun can help you extract maximum value from the Solaris 10 Operating System.

Multithreaded Kernel:

The basic purpose to use threads in Solaris kernel for scheduling and execution. The kernel schedules interrupts and kernel services as regular kernel threads. This feature provides interrupt scalability and low-latency interrupt response.

Real-time architecture:

The Solaris kernel was specially designed to provide real-time capabilities. The combination of the preempt able kernel, kernel interrupts as threads, fixed priority scheduling, high resolution timers, makes Solaris an ideal environment for real time applications.

Multithreaded Process Execution:

In Solaris, a process can have more than one thread of execution. These threads are able to run on one or more processors at the same time. It means that a single process is able to use multiple processors for concurrent thread execution. So multiple processor platforms can be used effectively.

Symmetric Multiprocessor:

Solaris is implemented on systems ranging from single processor system to 64 processor symmetric multiprocessor servers. Solaris provides linear scalability up to the currently supported maximum of 64 processors.

Usage of Solaris:

The usages of Solaris operating system are given below:

The above are the most common uses of the Solaris and still there are other usages of the operating system.


Linux is an operating system, a software program that controls your computer. Most vendors load an operating system onto the hard drive of a PC before delivering the PC, so, unless the hard drive of your PC has failed, you may not understand the function of an operating system.

An operating system solves several problems arising from hardware variation. As you're aware, no two PC models (or models of other computers, for that matter) have identical hardware. For example, some PCs have an IDE hard drive, whereas others have a SCSI hard drive. Some PCs have one hard drive, others have two or more. Most PCs have a CD-ROM drive, but some do not. Some PCs have an Intel Pentium CPU, whereas others have an AMD K-6, and so on. Suppose that, in a world without operating systems, you're programming a new PC application, perhaps a new multimedia word processor. Your application must cope with all the possible variations of PC hardware. As a result, it becomes bulky and complex. Users don't like it because it consumes too much hard drive space, takes a long time to load, and- because of its size and complexity- has more bugs than it should.

Operating systems solve this problem by providing a single standard way for applications to access hardware devices. When an operating system exists, applications can be more compact, because they share the commonly used code for accessing the hardware. Applications can also be more reliable because this code is written only once, and by expert programmers, rather than by every application programmers.

As you'll soon learn, operating systems do many other things as well; for example, they generally provide a filesystem so that you can store and retrieve data, and a user interface so that you can control the operation of your computer. However, if you think of a computer's operating system as its subconscious mind, you won't be far off the mark. It's the computer's conscious mind- applications such as word processors and spreadsheets- that do useful work. But, without the subconscious- the operating system- the computer would cease breathing and applications would not function.

Linux is a generic term referring to Unix-like computer operating systems based on the Linux kernel. Their development is one of the most prominent examples of free and open source software collaboration; typically all the underlying source code can be used, freely modified, and redistributed, both commercially and non-commercially, by anyone under licenses such as the GNU General Public License. Typically Linux is packaged in a format known as a Linux distribution for desktop and server use. Linux distributions include the Linux kernel and all of the supporting software required to run a complete system, such as utilities and libraries, the X Window System, the GNOME and KDE desktop environments, and the Apache HTTP Server. Commonly-used applications with desktop Linux systems include the Mozilla Firefox web-browser and the office application suite.

Linux can be installed on a wide variety of computer hardware, ranging from embedded devices such as mobile phones and wristwatches to mainframes and supercomputers. Linux is predominantly known for its use in servers; in 2007 Linux's overall share of the server market was estimated at 12.7%, while a 2008 estimate suggested that 60% of all web servers ran Linux. Most desktop computers run either Mac OS X or Microsoft Windows, with Linux having only 1–2% of the desktop market. However, desktop use of Linux has become increasingly popular in recent years, partly owing to the popular Ubuntu distribution and the emergence of netbooks. The name "Linux" comes from the Linux kernel, originally written in 1991 by Linus Torvalds. The contribution of a supporting Userland in the form of system tools and libraries from the GNU Project (announced in 1983 by Richard Stallman) is the basis for the Free Software Foundation's preferred name GNU/Linux.

Linux is mostly packaged in the form which is known as Linux distribution and this form is widely used by all the desktop and server users. This package consists of the Linux kernel and all the softwares that are required to support and run all the application like libraries and utilities. This operating system can be installed on a wide variety of hardware devices like mainframes, supercomputers and mobile devices and so on.




Viruses are less of a threat on Linux. The very way a Linux system is designed makes it very difficult for a virus to function as it does in Windows. This also applies to spyware, malware, etc. The fact that almost no viruses are written for Linux also adds a nicer sense of warmth. Wouldn't be nice to read the almost endless stream of security holes in Windows and know it does not apply to you?


Linux is in a constant state of development and improvement by professional and semi-professional developers who donate their time and skills to the various projects. In addition, the majority of the system and available applications are Open source, so if you wish and you had the ability, you could add any feature you needed. Linux also has the ability to expand the life of many systems as it's reduced overhead and need for system resources means that it will run great on older machines.


Yes, support. As hard as it is to accept, you can easily get support when you do run into difficulties. In addition to the plethora of online forms, both independant and those provided by the distro supplier, there are also more and more 3rd party service providers that offer service contracts for Linux systems. Good to have in a corporate/business environment. There is also support offered by more and more traditional Technology names such as Dell, IBM, Novell, Sun and others. And finally, for support a little closer to home, most major cities have Linux User Groups that can and do offer help and advice. Help and Support IS available and does not usually mean spending hours on hold to speak to someone in a call center on the other side of the planet.


Personally, this is one of the most important reasons why I switched. Linux gave me the chance to learn new skills, gain deeper insights into how computers work and provided an excellent platform to develop on. Some people may be satisfied with going through life with blinders on and living the "status-quo". For those that enjoy the how/what/why of life, Linux is an excellent choice.


Most people would put this at the top of the list. For me, cost is one of the least important reasons to switch to Linux. However, the cost advantage of Linux is huge. In a nutshell, you get the complete OS, thousands upon thousands of applications AND support for the grand total price of....$0! We're not talking a watered down, feature deprived OS either...we're talking a full-blown, complete, enterprise ready OS...for free. "But my time is worth something and the extra effort needed with Linux cost me money.", alright...and how much does it cost you when Windows bluescreens in the middle of editing a large report that hasn't been saved? Or how about when a virus or spyware prevents you from even using your system...probably costs you a lot.

Symbian OS

The Symbian is an operating system that has been especially designed for the smart phones as well as the mobile devices. This operating system includes all the relevant libraries, user interfaces, frameworks and many other tools that are developed by the Symbian Ltd. Symbian is the world's largest selling mobile operating system. Almost 45% of the smart phones make use of this operating system. The Symbian operating system underlies three basic system design principles which are given below:

These principles have been met by the Symbian operating system by making use of microkernel, request and call back approach, maintenance of separation between the engine and the user interface. The Symbian operating system has also been optimized for the devices that have low power batteries. Object oriented design known as Model View Controller (MVC) is being followed by the operating system as well as its many different applications. Many versions of Symbian operating system have been released like Symbian OS 6.0, Symbian OS 6.1, Symbian OS 7.0, Symbian OS 8.0, Symbian OS 8.1, Symbian OS 9 and Symbian OS 9.1.

Features of Symbian OS

Symbian OS is a very advanced and innovative operating system which comes up with many different features that support the various smart phones and mobile devices. Following are some of the key features of Symbian OS.

Integrated Multimode Mobile Telephony:

This operating system has the capability to integrate the computing power with the mobile telephony. This mobile based operating system has brought the advanced data services to the mass market. The 2.5G and 3G mobile phones mostly make use of this operating system.


A complete support is being provided by the Symbian OS operating system for the emails, fax, SMS, MMS and EMS and so on. This is a very required feature as peer to peer multimedia messaging is essentially performed in the 2.5G and 3G mobile phones.

Open Application Environment:

This operating system has allowed the mobile phones to be a platform for deploying various applications, services, programs and contents. This operating system also supports various languages like Java and C++ . Hence this operating system has allowed a wide range of applications to run on the mobile phones.

Standards and Interoperability:

A core set of Application Programming Interfaces (APIs) are provided by this operating system along with the flexible as well as modular implementation. Symbian OS also provides the technologies that are easily shared by all the mobile phones that do contain the Symbian OS. Another important factor is that Symbian OS also supports the key industry standards like IP v4 and v6, Java WAP, SyncML and Bluetooth wireless technology.


A multitasking kernel is added in the Symbian OS and along with that it is also fully object oriented and component based. It also provides middleware for communications, data management, graphics, application engines and lower level of GUI frameworks.


Instant access is provided by the Symbian OS to data of the user. Integrity of data is also maintained by this operating system.

Flexible User Interface Design:

Graphical User Interface design is given to this operating system which has also triggered the flexibility. Manufacturers, carriers, end users and enterprises are very much inclined towards using this innovative operating system.

Uses of Symbian OS:

The Symbian OS is being widely used these days. The most common usages of Symbian OS are given below:

The above are the most common applications of the Symbian OS although there can be many more as this operating system is getting popular day by day in the smart phones market.


Mac OS is the trademarked name for a series of graphical user interface-based operating systems developed by Apple Inc. (formerly Apple Computer, Inc.) for their Macintosh line of computer systems. The Macintosh user experience is credited with popularizing the graphical user interface. The original form of what Apple would later name the "Mac OS" was the integral and unnamed system software first introduced in 1984 with the original Macintosh, usually referred to simply as the System software.

Apple deliberately downplayed the existence of the operating system in the early years of the Macintosh to help make the machine appear more user-friendly and to distance it from other operating systems such as MS-DOS, which was more arcane and technically challenging. Much of this early system software was held in ROM, with updates typically provided free of charge by Apple dealers on floppy disk. As increasing disk storage capacity and performance gradually eliminated the need for fixing much of an advanced GUI operating system in ROM, Apple explored cloning while positioning major operating system upgrades as separate revenue-generating products, first with System 7.1 and System 7.5, then with Mac OS 7.6 in 1997.

Early versions of the Mac OS were compatible only with Motorola 68000-based Macintoshes. As Apple introduced computers with PowerPC hardware, the OS was upgraded to support this architecture as well. Mac OS 8.1 was the last version that could run on a 68000-class processor (the 68040). Mac OS X, which has superseded the "Classic" Mac OS, is compatible with both PowerPC and Intel processors through version 10.5 ("Leopard"). Version 10.6 ("Snow Leopard") supports only Intel processors.

The Mac OS can be divided into two families:

Mac OS X is the latest version of the Mac OS and it is having many new functionalities. Most of the users of Mac Os are now shifted to the Mac OS X. Mac OS is totally a graphical operating system and is also a very easy to use.

Features of Mac OS

This powerful operating system has got a number of features and few of which are discussed below:

Powerful and Simple:

The Mac OS is very powerful as well as easy to use. Each and every application of Mac from the desktop to its programs that are used every day is very simple yet elegant. It is easy to understand by the people who are even using it for the first time. It is also easy to use the internet over this operating system. This is a key feature because making things simpler needs integration of advanced technologies and Mac is having loads of these applications. Incredible performance, stunning graphics, unparallel stability and industry leading support for internet applications are also provided in this operating system.

Perfect Integration of Hardware and Software:

The Mac OS usually make use of the softwares that have been developed by the same company which is developing the Mac OS. This operating system is providing the integrated environment which makes it possible for everything to work together. The technologies of this operating system make full usage of 64 bit multicore processors. The Mac OS is able to communicate with the hardware to deliver incredible battery life by spinning down the hardware when it is inactive by making a decision that whether the CPU or GPU or best for a task and also be automatically dimming the screen in lowlight conditions.

Elegant Interface and Stunning Graphics:

The elegant user interface is the most striking feature of the Mac OS. The graphic technologies are built and implemented in order to leverage the advanced graphic processor. These technologies have made it possible to improve the smoothening animations, real time reflections and multiway chatting. The fonts are very clear and easy to understand. The graphics are very powerful.

Highly Secure by Design:

The design of this operating system has been developed in such a way that viruses hardly attack on the PC. It is also able to protect itself from many other malicious attacks.

Built for Compatibility:

The Mac OS is very versatile which makes it compatible in almost every environment. Almost all of the devices may handle this operating system because of this versatility.

Usage of Mac OS

The usage of Mac OS is getting increased day by day. The wide usage of Mac OS is among the MAC machines. Following are the basic usages of the Mac OS.