Operating Systems And Their Features Computer Science Essay

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When 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 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 systems.

Anyone who uses a computer is using an operating system, although very few people appreciate what an operating system is or what it does. The most visible part of an operating system is the graphical user interface (GUI) - and yet most of what an operating system does is completely invisible. 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.

Here are some of the OS available and their features.

LINUX

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.

Linux is distinguished from many popular operating systems in three important ways.

Linux is a cross-platform operating system that runs on many computer models. Only Unix, an ancestor of Linux, rivals Linux in this respect. In comparison, Windows 95 and Windows 98 run only on CPUs having the Intel architecture. Windows NT runs only on CPUs having the Intel architecture or the DEC Alpha.

Linux is free, in two senses. First, you may pay nothing to obtain and use Linux. On the other hand, you may choose to purchase Linux from a vendor who bundles Linux with special documentation or applications, or who provides technical support. However, even in this case, the cost of Linux is likely to be a fraction of what you'd pay for another operating system. So, Linux is free or nearly free in an economic sense.

Second, and more important, Linux and many Linux applications are distributed in source form. This makes it possible for you and others to modify or improve them. You're not free to do this with most operating systems, which are distributed in binary form. For example, you can't make changes to Microsoft Windows or Microsoft Word - only Microsoft can do that. Because of this freedom, Linux is being constantly improved and updated, far outpacing the rate of progress of any other operating system. For example, Linux will likely be the first operating system to support Intel's forthcoming Merced 64-bit CPU.

Linux has attractive features and performance. Free access to Linux source code lets programmers around the world implement new features, and tweak Linux to improve its performance and reliability. The best of these features and tweaks are incorporated in the standard Linux kernel or made available as kernel patches or applications. Not even Microsoft can mobilize and support a software development team as large and dedicated as the volunteer Linux software development team, which numbers in the hundreds of thousands, including programmers, code reviewers, and testers.

Linux Features and Performance

Characteristic

Linux

Windows NT

Solaris

Range of compatible hardware

Very wide

Modest

Narrow

Minimal hardware

386 PC

486PC

Pentium

Representative cost of hardware

$200

$1300

$1600

Average downtime

Very low

As low as 30min /week

Very low

Performance

High

Comparable to Linux

Half of Linux to same as Linux

Multi- processing capabilities

Excellent

Modest

Excellent

IP Security

Yes

Planned

1999

Ipv6

available

privately demonstrated

Beta

Overall user satisfaction, per Datapro

Highest

Lowest

Medium

Source code readily available

Yes

No

No

Installed base

Millions

Millions

Hundreds of thousands

As you can see, Linux fares well in this comparison. It runs on a wider range of hardware platforms and runs adequately on less costly and powerful systems. Moreover, the typical downtime of a Linux system is less than that of a Windows NT system and its performance surpasses that of a Solaris system. Its multi-processing capabilities exceed those of Windows NT and its support of advanced TCP/IP networking facilities is superior to that of Windows NT and Solaris. As a group, Linux users are more satisfied than Windows NT users and Solaris users. Linux source code is readily available. And, the Linux installed base dwarfs that of Solaris and approaches that of Windows NT.

DIFFERENT TYPES OF OS

Solaris:

Available Versions:

Solaris 8

Solaris 9

Solaris 10

Solaris is the UNIX-based operating system of Sun Microsystems with roots in the BSD operating system family. Up to the version below 3.(something) this operating system was called SunOS, this name was kept into the internal release information of current Solaris versions. The first version of SunOS was published in 1982. With the version 4.0 the new product name Solaris was introduced for SunOS releases as of 1989. The operating system Solaris 2.0 (SunOS 5.0) basing on the UNIX system V release 4 was published in July 1992.

The Primary boot subsystem VSN 2.0 proceeds after the Installation as a booting manager. After the booting procedure the CDE or optionally OpenWindow system is available as a GUI. Solaris fulfils the Open Group Unix98 specification. With the available Solaris Security Toolkit application it is possible to made specific protection settings for Solaris.

Field of Application

- CAD (computer aided design) applications

- Stable system for databases, data centre

- Intranet server as well as Internet or file server, Internet client

Structure information

- Multi-processor capable of up to 8 CPUs (Kernel limited to 21 CPUs)

- UNIX derivat

- Realtime OS (timing up to 1 nanosecond)

- 64-bit operating system (UltraSparc), 32-bit on x86, (Intel)

- Monolithic Kernel

System Environment

- Optional CDE 1.4 or OpenWindows 6.4.1

- SPARC platform and Intel processors, PowerPC

- supports new hardware technologies like USB, FireWire, SCSI, Hot Plug, ACPI

- Scalability: more than of 4 gbyte RAM, max. 64 CPUs

- File system: UFS (0x83), logging of all writing processes, protection against inconsistencies

- Read/Write: FAT, FAT32, ISO9660

- Java support, Perl integrated for CGI programming among others

Strength

- Support LDAP authentification and NDS

- Supports automatic and dynamic reconfiguration of hardware devices

- Cover various Internet and intranet applications like DNA, Senmail, IPv6, IPsec

- High Internet Security

Symbian OS

Symbian is an operating system (OS) designed for mobile devices and smartphones, with associated libraries, user interface, frameworks and reference implementations of common tools, originally developed by Symbian Ltd. It was a descendant of Psion's EPOC and runs exclusively on ARM processors, although an unreleased x86 port existed.

Some of the principle design features in the simplest of forms are:

User data is sacred

User time is precious

All resources are scarce

Ubiquitous use of servers: typically, resources are brokered by servers; since the kernel ilself is a server, this includes kernel-owned resources represented by R classes

Pervasive asynchronous services; all resources are available to mulitple simultaneous clients

Rigorous separation of user interfaces from services

Rigorous separation of application user interfaces from engines

Engine reuse and openness of engine APIs

Pervasive support for instant availability and isntant switching of applications

Always on systems, capable of running forever

Symbian OS certainly aims at unequaled robustness, making strong guarentees about the integrity and safety of user data and the ability of the system to run without failure (to be crash-proofed). From the beginning, it has also aimed to be easy and intuitiveto use and fully driven by a graphical user interface (gui). Perhaps as important as anything else, the OS set out from the beginning to be extensible, providing application programming interfaces (APIs), including native APIs as well as support for the VISUAL BASIC- like OPL language and Java.

Services:

1. Generic OS Services Block

2. Multimedia and Graphics Services Block

3. Connectivity Services

MAC OS

Mac OS X is the world's most advanced operating system. Built on a UNIX foundation and designed to be simple and intuitive, Mac Os is highly secure, compatible, and easy to use.

Mac OS X is both easy to use and powerful. Everything - from the desktop you see when you start up your Mac to the applications you use every day - is designed with simplicity and elegance in mind. So whether you're browsing the web, checking your email, or video chatting with a friend on another continent,* getting things done is at once easy to learn, simple to perform, and fun to do. Of course, making amazing things simple takes seriously advanced technologies, and Mac OS X is loaded with them. Not only is it built on a rock-solid, time-tested UNIX foundation that provides unparalleled stability, it also delivers incredible performance, stunning graphics, and industry-leading support for Internet standards.

FEATURES

One of the major differences between the previous versions of Mac OS and OS X was the addition of the Aqua GUI, a graphical user interface with water-like elements. Every window element, text, graphics, or widgets is drawn on-screen using the anti-aliasing technology. ColorSync, a technology introduced many years before, was improved and built into the core drawing engine, to provide color matching for printing and multimedia professionals. Also, drop shadows were added around windows and isolated text elements to provide a sense of depth. New interface elements were integrated, including sheets (document modal dialog boxes attached to specific windows) and drawers.

Apple has continued to change aspects of the OS X appearance and design, particularly with tweaks to the appearance of windows and the menu bar. One example of a UI behavioral change is that previewed video and audio files no longer have progress bars in column view; instead, they have mouse-over start and stop buttons as of 10.5.

The human interface guidelines published by Apple for Mac OS X are followed by many applications, giving them consistent user interface and keyboard shortcuts. In addition, new services for applications are included, which include spelling and grammar checkers, special characters palette, color picker, font chooser and dictionary; these global features are present in every Cocoa application, adding consistency. The graphics system OpenGL composites windows onto the screen to allow hardware-accelerated drawing. This technology, introduced in version 10.2, is called Quartz Extreme, a component of Quartz. Quartz's internal imaging model correlates well with the Portable Document Format (PDF) imaging model, making it easy to output PDF to multiple devices. As a side result, PDF viewing is a built-in feature.

In version 10.3, Apple added Exposé, a feature which includes three functions to help accessibility between windows and desktop. Its functions are to instantly display all open windows as thumbnails for easy navigation to different tasks, display all open windows as thumbnails from the current application, and hide all windows to access the desktop. Also, FileVault was introduced, which is an optional encryption of the user's files with Advanced Encryption Standard (AES-128).

Features introduced in version 10.4 include Automator, an application designed to create an automatic workflow for different tasks; Dashboard, a full-screen group of small applications called desktop widgets that can be called up and dismissed in one keystroke; and Front Row, a media viewer interface accessed by the Apple Remote. Moreover, the Sync Services were included, which is a system that allows applications to access a centralized extensible database for various elements of user data, including calendar and contact items. The operating system then managed conflicting edits and data consistency

As of version 10.5, all system icons are scalable up to 512-512 pixels, to accommodate various places where they appear in larger size, including for example the Cover Flow view, a three-dimensional graphical user interface included with iTunes, the Finder, and other Apple products for visually skimming through files and digital media libraries via cover artwork. This version includes Spaces, a virtual desktop implementation which enables the user to have more than one desktop and display them in an Exposé-like interface. Mac OS X v10.5 includes an automatic backup technology called Time Machine, which provides the ability to view and restore previous versions of files and application data; and Screen Sharing was built in for the first time.

Finder is a file browser allowing quick access to all areas of the computer, which has been modified throughout subsequent releases of Mac OS X. Quick Look is part of Mac OS X Leopard's Finder. It allows for dynamic previews of files, including videos and multi-page documents, without opening their parent applications. Spotlight search technology, which is integrated into the Finder since Mac OS X Tiger, allows rapid real-time searches of data files; mail messages; photos; and other information based on item properties (Meta data) and/or content. Mac OS X makes use of a Dock, which holds file and folder shortcuts as well as minimized windows. Mac OS X Architecture implements a layered framework. The layered framework aids rapid development of applications by providing existing code for common tasks.

Windows Moblie Edition

Since the early 1990's technology has evolved to such an degree that computing and communications are now possible from the smallest, pocket sized devices, while delivering fantastic visuals and speed. In order to embrace this shift in technological capability Microsoft has been at the forefront of software development, creating applications and operating systems that fit the specific requirements of the mobile device. One such operating system is Windows Mobile. In essence a basic os, based on the Microsoft Win32 API, Windows Mobile was designed specifically for handheld devices, originally the Pocket PC, then Smartphone's and Portable Media Centers. In its earliest form the windows mobile operating system was similar in look, feel and functionality to Windows 98, delivering basic application delivery and minimal third-party support for common hardware and software components.

Today however Windows Mobile is more in tune with the 'Live' suite Microsoft are pushing, which has a dazzling array of onscreen informatics - e-mail messages, tasks, apointments and ownership details. As with Windows XP, the taskbar holds the current time, volume connectivity status, and resource processing. The notification bar holds all the standard desktop iconic representations such as running programs, connectivity, etc. In terms of application productivity the Mobile Office suite delivers impressively similar functionality to its big brother Microsoft Office. Word, Excel, Outlook and PowerPoint all deliver excellent functionality and while there are some gaps in functionality, for example table and image insertion are two areas that are missing, you won't see much of a drop off. Windows Media Player also has extensive operability providing users with the capability to play WMA, WMV, MP3 and AVI files, however MPEG's are not supported and WAV files require a separate player. There is also an abundance of personalization settings, from configuring background images and themes. Most importantly however is the development of ActiveSync and improved server interfacing for fast and secure synchronization of data to any desktop application.

Windows Mobile for Pocket PC carries these standard features in most of its versions:

Today Screen shows the current date, owner information, upcoming appointments, e-mail messages, and tasks. (Is now Home screen in later WM6.5 builds)

The taskbar shows the current time and the volume.

Office Mobile a suite of Mobile versions of Microsoft Office applications

Outlook Mobile comes with Windows Mobile.

Internet Explorer Mobile is an Internet browser developed by Microsoft for Pocket PC and Handheld PC that comes loaded by default with Windows Mobile and Windows CE for Handheld PC.

Windows Media Player for Windows Mobile.

Client for Point-to-Point Tunneling Protocol (PPTP) virtual private network (VPNs).

Internet Connection Sharing (ICS) which in mobile phones allows attached computers to share internet connections via USB and Bluetooth.

Coherent file system similar to that of Windows 9/Windows NT and support for many of the same file types.

Ability to multitask.

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