Microsoft Windows

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Microsoft Windows
Windows logo
Screenshot of Windows Vista, the newest release of Microsoft Windows.
Company/ developer: Microsoft Corporation
OS family: MS-DOS-based, Windows NT, Windows 9x, Windows CE
Source model: Closed source
License: MS- EULA
Working state: Current
Website: Microsoft Windows

Microsoft Windows is a family of operating systems by Microsoft. They can run on several types of platforms such as servers, embedded devices and, most typically, on personal computers. 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 (GUI) popularized by the 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 approximately 90% of the client operating system market.


The term Windows collectively describes any or all of several generations of Microsoft (MS) operating system (OS) 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 MS-DOS, Windows allowed users to execute multiple graphical applications at the same time, through cooperative 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) improved 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. However, 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. Windows 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 Windows XP.

32-bit operating systems

This family of Windows systems was designed and marketed for higher-reliability business use, and was unencumbered by any Microsoft 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 codeveloped 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 ( Itanium) architecture, and later the AMD64/ EM64T (or x64 in Microsoft terminology) architectures, 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/EM64T systems, and Windows Server 2003, in both IA-64 and x64 editions. The x64 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. Windows Vista will be the first end-user version of Windows that Microsoft plans to release simultaneously in 32-bit and x64 editions.


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 a new kernel. 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. This new version was widely praised in computer magazines. 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 Centre" 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, the successor to Windows XP, is due to be released on January 30, 2007. Windows Server 2003's successor will be Windows Server "Longhorn", and has a planned release date in the second half of 2007.


Security has been a hot topic with Windows for many years, and even Microsoft itself has been the victim of security breaches. Due in some part to the widespread usage of Windows on personal computers, as well as a number of technical reasons there is reportedly a five-fold greater amount of malware for Windows than other operating systems such as GNU/ 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, was installed by users more quickly than it might have been. 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 XP and Windows Server 2003, updates can be automatically downloaded and installed if the user selects to do so.

Windows Defender

On 6 January 2005, Microsoft released a beta version of Windows AntiSpyware, based upon the previously released Giant AntiSpyware. On 14 February 2006, Windows AntiSpyware became Windows Defender with the release of beta 2. Windows Defender is a freeware program designed to protect against spyware and other unwanted software.

Paul Thurrott's Supersite for Windows gave Defender Beta 2 a stellar review; it received more middling reviews from other publications such as PC Magazine. and CNet. Windows 2000 and Windows XP users can freely download the program from Microsoft's web site, and Microsoft has stated that Windows Defender will ship as part of Windows Vista.

Third-party analysis

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. The AOL National Cyber Security Alliance Online Safety Study of October 2004 determined that 80% of Windows users were infected by at least one spyware/ adware product. 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.

Emulation software

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

  • Wine – (Wine Is Not an Emulator) an almost complete free software/ open-source software implementation of the Windows API, allowing one to run most Windows applications on x86 Unix-based platforms, including GNU/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 GNU/ Linux.
  • ReactOS – open-source operating system, aimed to be compatible with existing Windows NT applications and drivers.
  • Project David – ambitious and controversial project to fully emulate Windows programs to run on other OSs.
  • Parallels Workstation - by Parallels, Inc.
  • Virtual PC - Virtual PC for Mac OS X is an emulation suite, and Virtual PC for Windows is a virtualization suite. The software was originally written by Connectix, and was subsequently acquired by Microsoft. Virtual PC for Mac emulates an x86-32 CPU, therefore can also support other OSs, but has specific support for Windows.
  • Darwine - this project intends to port and develop Wine as well as other supporting tools that will allow Darwin and Mac OS X users to run Microsoft Windows Applications, and to provide Win32 API compatibility at application source code level.

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