WEBEVALUATION

INTERNAL EXAMINOR EXTERNL EXAMINOR

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TOPIC

OPERATING SYSTEM

WEBSITES

1. www.wikipedia.org

2. www.techtrget.com

3. www.webopedia.com

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TOPIC: OPERATING SYSTEM

WEBSITE

http://en.wikipedia.org/wiki/Operating_system

Contents

1.   Types of operating systems

1.1   Real-time

1.2   Multi-user

1.3   Multi-tasking vs. single-tasking

1.4   Distributed

1.5   Templated

1.6   Embedded 2. Components

2.1 Kernel

2.2 Networking

2.3 Security

2.4 User interface

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Operating systemAn operating system (OS) is software that manages computer hardware and software resources

and provides common services forcomputer programs. The operating system is an essential component of

the system software in a computer system. Application programs usually require an operating system to

function.

Time-sharing operating systems schedule tasks for efficient use of the system and may also include

accounting software for cost allocation of processor time, mass storage, printing, and other resources.

For hardware functions such as input and output and memory allocation, the operating system acts as an

intermediary between programs and the computer hardware,[1][2] although the application code is usually

executed directly by the hardware and will frequently make a system call to an OS function or be

interrupted by it. Operating systems can be found on almost any device that contains a computer—

from cellular phones and video game consoles to supercomputers and web servers.

Types of operating systems

Real-time

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. They have an event-driven or time-sharing design and often aspects of both. An

event-driven system switches between tasks based on their priorities or external events while time-sharing

operating systems switch tasks based on clock interrupts. Time-sharing operating systems schedule tasks for

efficient use of the system and may also include accounting software for cost allocation of processor time,

mass storage, printing, and other resources.

Multi-user

A multi-user operating system allows multiple users to access a computer system at the same time.

Time-sharing systems and Internet servers can be classified as multi-user systems as they enable multiple-user

access to a computer through the sharing of time. Single-user operating systems have only one user but may

allow multiple programs to run at the same time.

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Multi-tasking vs. single-tasking

A multi-tasking operating system allows more than one program to be running at the same time, from

the point of view of human time scales. A single-tasking system has only one running program. Multi-tasking

can be of two types: pre-emptive and co-operative. In pre-emptive multitasking, the operating system slices the

CPU time and dedicates one slot to each of the programs. Unix-like operating systems such as Solaris and

Linux support pre-emptive multitasking, as does AmigaOS. Cooperative multitasking is achieved by relying

on each process to give time to the other processes in a defined manner.  16-bit versions of Microsoft Windows

used cooperative multi-tasking. 32-bit versions of both Windows NT and Win9x, used pre-emptive multi-

tasking. Mac OS prior to OS X used to support cooperative multitasking.

Distributed

A distributed operating system manages a group of independent computers and makes them appear to

be a single computer. The development of networked computers that could be linked and communicate with

each other gave rise to distributed computing. Distributed computations are carried out on more than one

machine. When computers in a group work in cooperation, they make a distributed system.

Templated

In an OS, distributed and cloud computing context, templating refers to creating a single virtual

machine image as a guest operating system, then saving it as a tool for multiple running virtual machines

(Gagne, 2012, p. 716). The technique is used both in virtualization and cloud computing management, and is

common in large server warehouses. 

Embedded

Embedded operating systems are designed to be used in embedded computer systems. They are

designed to operate on small machines like PDAs with less autonomy. They are able to operate with a limited

number of resources. They are very compact and extremely efficient by design. Windows CE and Minix 3 are

some examples of embedded operating systems.

Components

The components of an operating system all exist in order to make the different parts of a

computer work together. All user software needs to go through the operating system in order to

use any of the hardware, whether it be as simple as a mouse or keyboard or as complex as an

Internet component.

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Kernel

A kernel connects the application software to the hardware of a computer.

With the aid of the firmware and device drivers, the kernel provides the most basic level of

control over all of the computer's hardware devices. It manages memory access for programs in

the RAM, it determines which programs get access to which hardware resources, it sets up or

resets the CPU's operating states for optimal operation at all times, and it organizes the data for

long-term non-volatile storagewith file systems on such media as disks, tapes, flash memory, etc.

NetworkingCurrently most operating systems support a variety of networking protocols, hardware,

and applications for using them. This means that computers running dissimilar operating systems

can participate in a common network for sharing resources such as computing, files, printers, and

scanners using either wired or wireless connections. Networks can essentially allow a computer's

operating system to access the resources of a remote computer to support the same functions as it

could if those resources were connected directly to the local computer. This includes everything

from simple communication, to using networked file systems or even sharing another computer's

graphics or sound hardware. Some network services allow the resources of a computer to be

accessed transparently, such as SSH which allows networked users direct access to a computer's

command line interface.

Client/server networking allows a program on a computer, called a client, to connect via a

network to another computer, called a server. Servers offer (or host) various services to other

network computers and users. These services are usually provided through ports or numbered

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access points beyond the server's network address. Each port number is usually associated with a

maximum of one running program, which is responsible for handling requests to that port. A

daemon, being a user program, can in turn access the local hardware resources of that computer

by passing requests to the operating system kernel.

Many operating systems support one or more vendor-specific or open networking

protocols as well, for example, SNA on IBM systems, DECnet on systems from Digital

Equipment Corporation, and Microsoft-specific protocols (SMB) on Windows. Specific

protocols for specific tasks may also be supported such as NFS for file access. Protocols

like ESound, or esd can be easily extended over the network to provide sound from local

applications, on a remote system's sound hardware.

Security

A computer being secure depends on a number of technologies working properly. A

modern operating system provides access to a number of resources, which are available to

software running on the system, and to external devices like networks via the kernel.

The operating system must be capable of distinguishing between requests which should

be allowed to be processed, and others which should not be processed. While some systems may

simply distinguish between "privileged" and "non-privileged", systems commonly have a form

of requester identity, such as a user name. To establish identity there may be a process

of authentication. Often a username must be quoted, and each username may have a password.

Other methods of authentication, such as magnetic cards or biometric data, might be used

instead. In some cases, especially connections from the network, resources may be accessed with

no authentication at all (such as reading files over a network share). Also covered by the concept

of requester identity is authorization; the particular services and resources accessible by the

requester once logged into a system are tied to either the requester's user account or to the

variously configured groups of users to which the requester belongs.

In addition to the allow/disallow model of security, a system with a high level of security

will also offer auditing options. These would allow tracking of requests for access to resources

(such as, "who has been reading this file?"). Internal security, or security from an already

running program is only possible if all possibly harmful requests must be carried out through

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interrupts to the operating system kernel. If programs can directly access hardware and

resources, they cannot be secured.

External security involves a request from outside the computer, such as a login at a

connected console or some kind of network connection. External requests are often passed

through device drivers to the operating system's kernel, where they can be passed onto

applications, or carried out directly. Security of operating systems has long been a concern

because of highly sensitive data held on computers, both of a commercial and military nature.

The United States Government Department of Defense (DoD) created theTrusted Computer

System Evaluation Criteria (TCSEC) which is a standard that sets basic requirements for

assessing the effectiveness of security. This became of vital importance to operating system

makers, because the TCSEC was used to evaluate, classify and select trusted operating

systems being considered for the processing, storage and retrieval of sensitive or classified

information.

Internal security is especially relevant for multi-user systems; it allows each user of the

system to have private files that the other users cannot tamper with or read. Internal security is

also vital if auditing is to be of any use, since a program can potentially bypass the operating

system, inclusive of bypassing auditing.

User interface

A screenshot of the Bourne Again Shellcommand line. Each command is typed out after

the 'prompt', and then its output appears below, working its way down the screen. The current

command prompt is at the bottom.

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Every computer that is to be operated by an individual requires a user interface. The user

interface is usually referred to as a shelland is essential if human interaction is to be supported.

The user interface views the directory structure and requests services from the operating system

that will acquire data from input hardware devices, such as a keyboard, mouse or credit card

reader, and requests operating system services to display prompts, status messages and such

on output hardware devices, such as a video monitor or printer. The two most common forms of

a user interface have historically been the command-line interface, where computer commands

are typed out line-by-line, and the graphical user interface, where a visual environment (most

commonly aWIMP) is present.

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TOPIC: OPERATING SYSTEM

WEBSITE

http://whatis.techtarget.com/definition/operating-system-OS

CONTENTS

1. OERATING SYSTEM DEFINITION

2. SERVER OPERTING SYSTEM

3. MOBILE OPERATING SYSTEM

4. WHAT IS A MOBILE OPERATING SYSTEM

5. TYPES OF MOBILE OPERATING SYSTEM

6. POPULAR MOBILE OPERATING SYSTEM

1. Android OS (Google Inc.)

2. Bada (Samsung Electronics)

3. BlackBerry OS (Research In Motion)

4. iPhone OS / iOS (Apple)

5. MeeGo OS (Nokia and Intel)

6. Palm OS (Garnet OS)

7. Symbian OS (Nokia)

8. webOS (Palm/HP)

9. Windows Mobile (Windows Phone 7)

OPERATNG SYSTEM (OS)10

DEFINITION

 An operating system (sometimes abbreviated as "OS") is the program that, after being

initially loaded into the computer by a boot program, manages all the other programs in a

computer. The other programs are called applications or application programs. The application

programs make use of the operating system by making requests for services through a defined

application program interface (API). In addition, users can interact directly with the operating

system through a user interface such as a command language or a graphical user interface (GUI).

An operating system performs these services for applications:

In a multitasking operating system where multiple programs can be running at the same time,

the operating system determines which applications should run in what order and how much

time should be allowed for each application before giving another application a turn.

It manages the sharing of internal memory among multiple applications.

It handles input and output to and from attached hardware devices, such as hard disks,

printers, and dial-up ports.

It sends messages to each application or interactive user (or to a system operator) about

the status of operation and any errors that may have occurred.

It can offload the management of what are called batch jobs (for example, printing) so that

the initiating application is freed from this work.

On computers that can provide parallel processing, an operating system can manage how to

divide the program so that it runs on more than one processor at a time.

All major computer platforms (hardware and software) require and sometimes include an

operating system. Linux, Windows, VMS, OS/400, AIX, and z/OS are all examples of operating

systems.

SERVER OPERATING SYSTEM

server operating system, also called a server OS, is an operating system specifically designed to

run on servers, which are specialized computers that operate within a client/server architecture to

serve the requests of client computers on the network.

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The server operating system, or server OS, is the software layer on top of which other software

programs, or applications, can run on the server hardware. Server operating systems help enable

and facilitate typical server roles such as Web server, mail server, file server, database server,

application server and print server.

Popular server operating systems include Windows Server, Mac OS X Server, and variants of

Linux such as Red Hat Enterprise Linux (RHEL) and SUSE Linux Enterprise Server.

Mobile Operating Systems (Mobile OS) 

A mobile operating system, also called a mobile OS,  is an operating system that is specifically

designed to run on mobile devices such as mobile phones, smartphones, PDAs, tablet

computers and other handheld devices.

What is a Mobile Operating System (Mobile OS)?

Linux or Windows operating system controls our desktop or laptop computer,  a mobile

operating system is the software platform on top of which other programs can run on mobile

devices.

The operating system is responsible for determining the functions and features available on your

device, such as thumbwheel, keyboards, WAP, synchronization with applications, email, text

messaging and more.

The mobile OS will also determine which third-party applications (mobile apps) can be used on

your device.

Types of Mobile Operating Systems

When you purchase a mobile device the manufacturer will have chosen the operating system for

that specific device.  Often, you will want to learn about the mobile operating system before you

purchase a device to ensure compatibility and support for the mobile applications you want to

use.

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Popular Mobile Operating Systems

1. Android OS (Google Inc.)

The Android mobile operating system is Google's open and free software stack that includes an

operating system, middleware and also key applications for use on mobile devices, including

smartphones. Updates for the open source Android mobile operating system have been

developed under “dessert-inspired” codenames(Cupcake, Donut, Eclair, Gingerbread,

Honeycomb, Ice Cream Sandwich) with each new version arriving in alphabetical order with

new enhancements and improvements.

2. Bada (Samsung Electronics)

Bada is a proprietary Samsung mobile OS that was first launched in 2010. The Samsung Wave

was the first smartphone to use this mobile OS. Bada provides mobile features such as

multipoint-touch, 3D graphics and of course, application downloads and installation.

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3. BlackBerry OS (Research In Motion)

The BlackBerry OS is a proprietary mobile operating system developed by Research In Motion

for use on the company’s popular BlackBerry handheld devices. The BlackBerry platform is

popular with corporate users as itoffers synchronization with Microsoft Exchange, Lotus

Domino, Novell GroupWise email and other business software, when used with the BlackBerry

Enterprise Server.

4. iPhone OS / iOS (Apple)

Apple's iPhone OS was originally developed for use on its iPhone devices. Now, the mobile

operating system is referred to as iOS and is supported on a number of Apple devices including

the iPhone, iPad, iPad 2 and iPod Touch. The iOS mobile operating system is available only on

Apple's own manufactured devices as the company does not license the OS for third-party

hardware. Apple iOS is derived from Apple's Mac OS X operating system.

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5. MeeGo OS (Nokia and Intel)

A joint open source mobile operating system which is the result of merging two products based

on open source technologies: Maemo (Nokia) and Moblin (Intel).  MeeGo is a mobile OS

designed to work on a number of devices including smartphones, netbooks, tablets, in-vehicle

information systems and various devices using Intel Atom and ARMv7 architectures.

6. Palm OS (Garnet OS)

The Palm OS is a proprietary mobile operating system (PDA operating system) that was

originally released in 1996 on the Pilot 1000 handheld. Newer versions of the Palm OS have

added support for expansion ports, new processors, external memory cards, improved security

and support for ARM processors and smartphones. Palm OS 5 was extended to provide support

for a broad range of screen resolutions, wireless connections and enhanced multimedia

capabilities and is called Garnet OS.

7. Symbian OS (Nokia)

Symbian is a mobile operating system (OS) targeted at mobile phones that offers a high-level of

integration with communication and personal information management (PIM) functionality.

Symbian OS combines middleware with wireless communications through an integrated mailbox

and the integration of Java and PIM functionality (agenda and contacts). Nokia has made the

Symbian platform available under an alternative, open and direct model, to work with

some OEMs and the small community of platform development collaborators. Nokia does not

maintain Symbian as an open source development project.

8. webOS (Palm/HP)

WebOS is a mobile operating system that runs on the Linux kernel. WebOS was initially

developed by Palm as the successor to its Palm OS mobile operating system. It is a proprietary

Mobile OS which was eventually acquired by HP and now referred to as webOS (lower-case w)

in HP literature. HP uses webOS in a number of devices including several smartphones and HP

TouchPads. HP has pushed its webOS into the enterprise mobile market by focusing on

improving security features and management with the release of webOS 3.x. HP has also

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announced plans for a version of webOS to run within the Microsoft Windows operating system

and to be installed on all HP desktop and notebook computers in 2012.

9. Windows Mobile (Windows Phone 7)

Windows Mobile is Microsoft's mobile operating system used in smartphones and mobile

devices – with or without touchscreens. The Mobile OS is based on the Windows CE 5.2 kernel.

In 2010 Microsoft announced a new smartphone platform called Windows Phone 7.

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TOPIC: OPERATING SYSTEM

WEBSITE

http://www.webopedia.com/TERM/O/operating_system.html

CONTENTS

1. OPERATING SYSTEM

2. CLSSIFICATION OF OPERATING SYSTEM

MULTI USER

MULTI PROCESSING

MULTI TASING

MULTI THREADING

REAL TIME

3. HOW OPERATING SYSTEMS WORK

4. OPERATING SSTEM VIRTUALIZATION

5. NOS- NETWORK OPERATING SYSTEM

OS – OPERA TING SYSTEM

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The operating system is the most important program that runs on acomputer. 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 anddirectories on the disk, and controlling peripheral

devices such asdisk 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 programs 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.

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Classification of Operating systems

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.

Multitasking : Allows more than one program to run concurrently.

Multithreading : Allows different parts of a single program to run concurrently.

Real time: Responds to input instantly. General-purpose operating systems, such

as DOS and UNIX, are not real-time.

Operating systems provide a software platform on top of which other programs,

called application programs, can run. The application programs must be written to run on top of

a particular operating system. Your choice of operating system, therefore, determines to a great

extent the applications you can run. For PCs, the most popular operating systems are DOS, OS/2,

and Windows, but others are available, such as Linux.

As a user, you normally interact with the operating system through a set of commands.

For example, the DOS operating system contains commands such as COPY and RENAME

for copying files and changing the names of files, respectively. The commands are accepted

and executed by a part of the operating system called the command processor or command line

interpreter. Graphical user interfaces allow you to enter commands by pointing

and clicking at objects that appear on the screen.

How Operating Systems WorkWhen you turn on your computer, it's nice to think that you're in control. There's the

trusty computer mouse, which you can move anywhere on the screen, summoning up your music

library or Internet browser at the slightest whim. Although it's easy to feel like a director in front

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of your desktop or laptop, there's a lot going on inside, and the real man behind the curtain

handling the necessary tasks is the operating system.

Most desktop or laptop PCs come pre-loaded with Microsoft Windows. Macintosh

computers come pre-loaded with Mac OS X. Many corporate servers use the Linux or UNIX

operating systems. The operating system (OS) is the first thing loaded onto the computer --

without the operating system, a computer is useless.

More recently, operating systems have started to pop up in smaller computers as well. If

you like to tinker with electronic devices, you're probably pleased that operating systems can

now be found on many of the devices we use every day, from cell phones to wireless access

points. The computers used in these little devices have gotten so powerful that they can now

actually run an operating system and applications. The computer in a typical modern cell phone

is now more powerful than a desktop computer from 20 years ago, so this progression makes

sense and is a natural development.

The purpose of an operating system is to organize and control hardware and software so

that the device it lives in behaves in a flexible but predictable way. In this article, we'll tell you

what a piece of software must do to be called an operating system, show you how the operating

system in your desktop computer works and give you some examples of how to take control of

the other operating systems around you.

Operating system virtualizationOperating system virtualization refers to the use of software to allow system hardware to

run multiple instances of different operating systems concurrently, allowing you to run

different applications requiring different operating systems on one computer system. The

operating systems do not interfere with each other or the various applications. Not to be confused

with operating system-level virtualization, which is a type of server virtualization.

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NOS - network operating system

Abbreviated as NOS, a network operating system includes special functions for

connecting computers and devices into a local-area network (LAN). Some operating systems,

such as UNIX and theMac OS, have networking functions built in.

The term network operating system is generally reserved for software that enhances a

basic operating system by adding networking features. Novell Netware, Artisoft's

LANtastic, MicrosoftWindows Server, and Windows NT are examples of a NOS.

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