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Microsoft Windows is a family of operating systems by Microsoft for use on personal computers, although versions of Windows designed for servers, embedded devices, and other platforms also exist. Microsoft first introduced an operating environment named Windows in November 1985 as an add-on to MS-DOS in response to the growing trend of graphical user interfaces popularized by the Apple Macintosh. Microsoft Windows eventually came to dominate the world's personal computer market. At the 2004 IDC Directions conference, IDC Vice President Avneesh Saxena stated that Windows had around 90% of the client operating system market.IDC: Consolidation to Windows won't happen www.linuxworld.com.au

Microsoft Windows versions

The term Windows collectively describes any or all of several generations of Microsoft operating system products. These products are generally categorized as follows:

16-bit operating environments

The early versions of Windows were often thought of as just graphical user interfaces or desktops, mostly because they were started from MS-DOS and used it for file system services. However even the earliest 16-bit Windows versions already assumed many typical operating system functions, notably having their own executable file format and providing their own device drivers (timer, graphics, printer, mouse, keyboard and sound) for applications. Unlike DOS, Windows allowed users to execute multiple graphical applications at the same time, through co-operative multitasking. Finally, Windows implemented an elaborate, segment-based, software virtual memory scheme which allowed it to run applications larger than available memory: code segments and resources were swapped in and thrown away when memory became scarce, and data segments moved in memory when a given application had relinquished processor control, typically waiting for user input. Examples include Windows 1.0 (1985) and Windows 2.0 (1987) and its close relative Windows/286.

Hybrid 16/32-bit operating environments

Windows/386 introduced a 32-bit protected mode kernel and virtual machine monitor. For the duration of a Windows session, it created one or more virtual 8086 environments and provided device virtualization for the video card, keyboard, mouse, timer and interrupt controller inside each of them. The user-visible consequence was that it became possible to preemptively multitask multiple MS-DOS environments in separate windows (graphical applications required switching the window to full screen mode). Windows applications were still multi-tasked cooperatively inside one of such real-mode environments.

Windows 3.0 (1990) and Windows 3.1 (1992) perfected the design, mostly thanks to virtual memory and loadable virtual device drivers (VxDs) which allowed them to share arbitrary devices between multitasked DOS windows. Because of this, Windows applications could now run in 16-bit protected mode (when Windows was running in Standard or 386 Enhanced Mode), which gave them access to several megabytes of memory and removed the obligation to participate in the software virtual memory scheme. They still ran inside the same address space, where the segmented memory provided a degree of protection, and multi-tasked cooperatively. For Windows 3.0 Microsoft also rewrote critical operations from C into assembly, making this release faster and less memory-hungry than its predecessors.

Hybrid 16/32-bit operating systems

With the introduction of 32-bit File Access in Windows for Workgroups 3.11, Windows could finally stop relying on DOS for file management. Leveraging this, Windows 95 introduced Long File Names, reducing the 8.3 DOS to the role of a boot loader. MS-DOS was now bundled with Windows; this notably made it (partially) aware of long file names when its utilities were run from within Windows, but angered the competition. The most important novelty was the possibility of running 32-bit multi-threaded preemptively multitasked graphical programs. Alas, the necessity of keeping compatibility with 16-bit programs meant the GUI components were still 16-bit only and not fully reentrant, which resulted in reduced performance and stability.

There were three releases of Windows 95 (the first in 1995, then subsequent bug-fix versions in 1996 and 1997, only released to OEMs, which added extra features such as FAT32 support). Microsoft's next OS was Windows 98; there were two versions of this (the first in 1998 and the second, named "Windows 98 Second Edition", in 1999). In 2000, Microsoft released Windows Me (Me standing for Millennium Edition), which used the same core as Windows 98 but adopted the visual appearance of Windows 2000, as well as a new feature called System Restore, allowing the user to set the computer's settings back to an earlier date. It was not a very well received implementation, and many user problems occurred. Me was considered a stopgap to the day both product lines would be seamlessly merged. Microsoft left little time for Windows Me to become popular before announcing their next version of Windows which would be called XP.

32-bit operating systems

This family of Windows systems was designed and marketed for higher-reliability business use, and was unencumbered by any DOS heritage. The first release was Windows NT 3.1 (1993, numbered "3.1" to match the Windows version and to one-up OS/2 2.1, IBM's flagship OS co-developed by Microsoft and Windows NT's main competitor at the time), which was followed by NT 3.5 (1994), NT 3.51 (1995), and NT 4.0 (1996); the latter implemented the Windows 95 user interface. Microsoft then moved to combine their consumer and business operating systems. Their first attempt, Windows 2000, failed to meet their goals, and was released as a business system. The home consumer edition of Windows 2000, codenamed "Windows Neptune", ceased development and Microsoft released Windows Me in its place. Eventually "Neptune" was merged into their new project, Whistler, which later became Windows XP. Since then, a new business system, Windows Server 2003, has expanded the top end of the range, and the forthcoming Windows Vista will complete it. Windows CE, Microsoft's offering in the mobile and embedded markets, is also a true 32-bit operating system.

64-bit operating systems

Windows NT included support for several different platforms before the x86-based personal computer became dominant in the professional world. Versions of NT from 3.1 to 4.0 supported DEC Alpha and MIPS R4000, which were 64-bit processors, although the operating system treated them as 32-bit processors.

With the introduction of the IA-64 architecture (or Itanium, after the processors that implement it), and later the AMD64 architecture (also known as x86-64, x64 by Microsoft, and implemented by Intel as EM64T), Microsoft released new versions of its more contemporary operating systems to support them. The modern 64-bit Windows family comprises Windows XP 64-bit Edition for IA-64 systems, Windows XP Professional x64 Edition for AMD64 systems, and Windows Server 2003, in versions for both IA-64 and AMD64. The AMD64 versions of Windows XP Professional and Server 2003 were released on April 25, 2005, while the IA-64 versions were released at the same time as their mainstream x86 (32-bit) counterparts. The upcoming Windows Vista will be the first operating system to truly embrace 64-bit computing and has been designed from the ground up instead of an afterthought, as the Windows XP Professional x64 Edition and Windows Server 2003 SP1 x64 was.

Microsoft Windows history

Microsoft has taken two parallel routes in Operating Systems. One route has been the home user and the other has been the professional IT user. The dual route has generally led to the home versions with more "eye candy" and less functionality in networking and security and professional versions with less "eye candy" and better networking and security.

The first independent version of Microsoft Windows, version 1.0, released in November, 1985, lacked a degree of functionality and achieved little popularity. Windows 1.0 did not provide a complete operating system; rather, it extended MS-DOS. Microsoft Windows version 2.0 was released in November, 1987 and was slightly more popular than its predecessor. Windows 2.03 (release date January 1988) had changed the OS from tiled windows to overlapping windows. The result of this change led to Apple Computer filing a suit against Microsoft alleging infringement on Apple's copyrights.

Microsoft Windows version 3.0, released in 1990, was the first Microsoft Windows version to achieve broad commercial success, selling 2 million copies in the first six months. It featured improvements to the user interface and to multitasking capabilities. In August 1995, Microsoft released Windows 95, which made further changes to the user interface and was the first Windows version to utilize multitasking.

In July 1993, Microsoft released Windows NT based on IBM OS/2 technology (which Microsoft had been co-developing for several years prior). NT was considered to be the professional OS. NT and the Windows non-professional line would later be fused together to create Windows XP.

The next in line was Microsoft Windows 98 released in June, 1998. Substantially criticized for its slowness compared with Windows 95, many of its basic problems were later rectified with the release of Windows 98 Second Edition in 1999.

As part of its professional line, Microsoft released Windows 2000 in February 2000. The consumer version following Windows 98 was Windows Me (Windows Millennium Edition). Released in September, 2000, Windows Me attempted to implement a number of new technologies for Microsoft: most notably publicized was "Universal Plug and Play." However, the OS was substantially criticized for its lack of compatibility and stability.

In October 2001, Microsoft released Windows XP, a version built on the Windows NT kernel that also retained the consumer-oriented usability of Windows 95 and its successors. It shipped in two distinct editions, "Home" and "Professional", the former lacking many of the superior security and networking features of the Professional edition. Additionally, the "Media Center" edition was released in 2003, with an emphasis on support for DVD and TV functionality including program recording and a remote control.

In April 2003, Windows Server 2003 was introduced, replacing the Windows 2000 line of server products with a number of new features and a strong focus on security; this was followed in December 2005 by Windows Server 2003 R2.

Windows Vista and Windows Server "Longhorn", the successors to Windows XP and Windows Server 2003 respectively, are currently under development.

Interface

The most obvious feature of Windows is a Window, or a container for other graphical objects. A Window in Microsoft Windows typically contains a status bar, title bar, minimize and maximize buttons, close button, and system menu (also called the windows menu or control menu). Another prominent feature since Windows 95 and NT 4.0 is the desktop, which holds various icons that the user can double-click to open. The Start Button and Start Menu, attached to the taskbar and typically below the desktop, gives users access to installed programs and many of the other features of the operating system.

Due to these and features, Windows makes it possible to perform most common tasks, some quite complex, with very little computer knowledge. Windows also comes with features to help the disabled through its accessibility options. Under Windows XP, these features include the Narrator, Magnifier and contrast display mode.

Widespread Usage

Microsoft Windows is installed on the vast majority of personal computers. A July 2005 poll of Network Computing magazine readers found that 90% of their organizations used Microsoft's desktop operating systems.Reader Poll www.networkcomputing.com It has achieved enormous market penetration due to the domination of MS-DOS in the early days of PC compatible computers (IBM PC, and various clones). It is also the primary platform for Microsoft Office and most non-console computer games.

The widespread use of Microsoft's operating system has benefited from not being tied to the success of one hardware manufacturer and from Microsoft's willingness to license the operating system to manufacturers. This is in contrast with Apple Computer, which does not license Mac OS X to other manufacturers. However, the wide spectrum of possible hardware permutations with Microsoft Windows is also seen as a major source of computer problems because of hardware/software incompatibilities for consumers.

In the past, companies who wanted to be in the computer business had to create their own operating systems (such as the Amiga, BBC Micro or ZX Spectrum) or choose another OS; even an exclusive license with one vendor was significantly cheaper than developing and supporting a new operating system and software base.

Due to Microsoft's extensive licensing agreements with many computer vendors, Windows presently comes pre-installed on most computers as a bundled OEM version, making it the default or only choice for most of the market.

For some consumers, Windows is the only valid option for a computing environment, or it is mandated by their workplace; additionally, an unfamiliarity with other operating systems results in a lack of desire to switch to other operating systems. A significant percentage of computer users simply lack the technical knowledge needed to install an operating system.

Finally, the large base of software available exclusively for the Windows family of operating systems has become the single largest self-perpetuating reason for the popularity of Windows. In recent years, many companies have been started with the sole intention of releasing Windows software; the fact that there is already a large customer base in place is reason enough for such companies to spend their resources solely on Windows software development. As a result, the fact that many companies are supporting Windows exclusively is a self-reinforcing reason for customers to choose Windows.

Maintaining compatibility in a new release of Windows with this large collection of software designed to run on older flavors of Windows consumes a large part of the resources of the Windows development team.

Security

Security has been a major weakness of Windows for many years, and even Microsoft itself has been the victim of cracks and hacks. Due to the widespread usage of Windows on personal computers, many malicious developers have targeted Windows rather than the lesser used operating systems such as Linux, Unix, Mac OS X, and FreeBSD. Windows was originally designed for ease-of-use on a single-user PC without a network connection, and did not have security features built in from the outset. Windows NT and its successors are designed for security (including on a network) and multi-user PCs, but was not designed for Internet security in mind as much since when it was first developed, the Internet was less important. Combined with occasionally flawed code (such as buffer overflows), Windows is a frequent target of worms and virus writers. Furthermore, until Windows Server 2003 most versions of even Windows NT were shipped with important security features disabled by default, and vulnerable (albeit useful) system services enabled by default. In June 2005, Bruce Schneier's Counterpane Internet Security reported that it had seen over 1,000 new viruses and worms in the previous six months.

Microsoft publicly admitted their ongoing security problems shortly after the turn of the century and now claims to regard security as their number one priority. The much-needed Automatic Update came first with Windows Me. As a result, Service Pack 2 for Windows XP, as well as Windows Server 2003, greatly increased the security of the operating system. Microsoft releases security patches through its Windows Update service approximately once a month (usually the second Tuesday of the month), although critical updates are made available at shorter intervals when necessary. In Windows 2000 (SP3 and later), Windows Me, Windows XP and Windows Server 2003, updates can be automatically downloaded and installed if the user selects to do so.

As another step in their focus on security, Microsoft has released a beta version of Windows Defender (formerly Windows AntiSpyware and Giant AntiSpyware) a free program designed to protect against spyware and other unwanted software. The program has generally been well received. Windows XP users can download the program for free from Microsoft's web site, and Microsoft has stated that Windows Defender will ship as part of their upcoming new operating system *, Windows Vista.

A study conducted by Kevin Mitnick and marketing communications firm Avantgarde found that an unprotected and unpatched Windows XP system lasted only 4 minutes on the Internet before it was compromised Automated “Bots” Overtake PCs Without Firewalls Within 4 Minutes www.avantgarde.com. The AOL/Cyber Security Alliance Online Safety Study of October 2004 determined that 80% of Windows users were infected by at least one spyware/adware product.[http://www.staysafeonline.info/pdf/safety_study_v04.pdf Safety Study www.staysafeonline.info (pdf) Much documentation is available describing how to increase the security of Microsoft Windows products. Typical suggestions include deploying Microsoft Windows behind a hardware or software firewall, running anti-virus and anti-spyware software, and installing patches as they become available through Windows Update.

Windows emulation software

Emulation allows the use of some Windows applications without using Microsoft Windows. These include:

  • WINE – an almost complete free software/open source software implementation of the Windows API, allowing one to run some Windows applications on x86 Unix-based platforms, including Linux.
  • CrossOver Office – a commercially packaged WINE with licensed fonts. Its developers are regular contributors to WINE, and focus on WINE running officially supported applications.
  • Cedega (formerly known as WineX) – TransGaming Technologies' proprietary fork of WINE, which is designed specifically for running games written for Microsoft Windows under Linux.
  • ReactOS – open source operating system, aimed to be compatible with existing Windows NT applications and drivers.
  • Freedows and Alliance OS – a very ambitious project, and a subsequent spinoff, that tried to clone Windows but withered away.
  • Project David – ambitious and controversial project to fully emulate Windows programs to run on other OSs.
  • Win4Lin - Win4Lin is a virtual machine technology that allows Windows to run as an application on Linux.

See also

References

External links

Official

Tips and documentation

Programming Microsoft Windows

Libraries

Reviews and evaluation

Other

Microsoft Windows | Operating systems

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