Microsoft Windows

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Microsoft Windows
Windows logo

Screenshot of Windows Vista
Company / developer Microsoft Corporation
OS family MS-DOS/9x-based, Windows CE, Windows NT
Working state Publicly released
Source model Closed source / Shared source
Latest stable release Windows Vista SP1, Windows Server 2008
NT 6.0.6001
 (February 4, 2008) [+/−]
Latest unstable release Windows 7
NT 6.1.7000
 (January 7, 2009) [+/−]
License MS-EULA

Microsoft Windows is a series of software operating systems and graphical user interfaces produced by Microsoft. Microsoft first introduced an operating environment named Windows in November 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces (GUIs).[1] Microsoft Windows came to dominate the world's personal computer market, overtaking Mac OS, which had been introduced previously. At the 2004 IDC Directions conference, it was stated that Windows had approximately 90% of the client operating system market.[2] The most recent client version of Windows is Windows Vista; the most recent server version is Windows Server 2008. Vista's successor, Windows 7 (currently in public beta) is slated to be released between July 1, 2009 and June 30, 2010.



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

Early versions

The history of Windows dates back to September 1981, when the project named "Interface Manager" was started. It was announced in November 1983 (after the Apple Lisa, but before the Macintosh) under the name "Windows", but Windows 1.0 was not released until November 1985.[3] The shell of Windows 1.0 was a program known as the MS-DOS Executive. Other supplied programs are Calculator, Calendar, Cardfile, Clipboard viewer, Clock, Control Panel, Notepad, Paint, Reversi, Terminal, and Write. Windows 1.0 does not allow overlapping windows, due to Apple Computer owning this feature. Instead all windows are tiled. Only dialog boxes can appear over other windows.

Windows 2.0 was released in October 1987 and featured several improvements to the user interface and memory management.[4] Windows 2.0 allowed application windows to overlap each other and also introduced more sophisticated keyboard-shortcuts. It could also make use of expanded memory.

Windows 2.1 was released in two different flavors: Windows/386 employed the 386 virtual 8086 mode to multitask several DOS programs, and the paged memory model to emulate expanded memory using available extended memory. Windows/286 (which, despite its name, would run on the 8086) still ran in real mode, but could make use of the high memory area.

The early versions of Windows were often thought of as simply graphical user interfaces, mostly because they ran on top of MS-DOS and used it for file system services.[5] 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. 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.[citation needed]

+ Windows OS market share
Source Hitslink[6] Awio[7] XiTi[8] OneStat[9]
Date January 2009 January 2009 December 2008 Dec 8 2008
All versions 88.26%[2] - 93.30% -
Windows XP 63.76% 71.73% 66.04% 72.02%
Windows Vista 22.48% 13.72% 24.47% 21.16%
Windows 2000 1.37% 2.08% 1.23% 0.54%
Windows 98 0.23% 0.54% 0.27% -
Windows 2003 - 0.69% 0.77% -
Windows ME 0.14% 0.22% 0.11% -
Windows 7 (Beta) 0.10% - - -
Windows NT 0.09% - 0.02% -
Windows CE 0.05% - 0.03% -
Windows 95 0.01%[10] - 0.01% -
Windows other - - 0.36% -

Windows 3.0 and 3.1

Windows 3.0 (1990) and Windows 3.1 (1992) improved the design, mostly because of virtual memory and loadable virtual device drivers (VxDs) which allowed them to share arbitrary devices between multitasked DOS windows.[citation needed] Also, Windows applications could now run in 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.[citation needed] With the introduction of the Windows for Workgroups 3.11, Windows was able to bypass DOS for file management operations using 32-bit file access.[citation needed]

Windows 95, 98 and Me

Windows 95 featured a new user interface, supported long file names, could automatically detect and configure installed hardware (plug and play), natively ran 32-bit applications, and featured several technological improvements that increased its stability over Windows 3.1. Windows 95 uses pre-emptive multitasking and runs each 32-bit application in a separate address space. This makes it harder for a single buggy application to crash the whole system. It was still not a secure multi-user operating system like Windows NT as a strict separation between applications was not enforced by the kernel. The API was a subset of the Win32 API supported by Windows NT, notably lacking support for Unicode and functions related to security. Windows 95 was now bundled together with MS-DOS 7.0, however its role was mostly delegated to that of a boot loader.

There were several releases of Windows 95; the first in 1995, with Service Pack 1 following in December which included Internet Explorer 2.0. Subsequent versions were only available with the purchase of a new computer and were called OEM Service Releases. OSR1 was equivalent to Windows 95 with SP1. OSR2 (also called Windows 95 B) included support for FAT32 and UDMA and shipped with Internet Explorer 3.0. OSR 2.1 included basic support for USB and OSR 2.5 (also called Windows 95 C) shipped with Internet Explorer 4.0.

Microsoft's next OS was Windows 98, which had two versions; 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 some aspects of Windows 2000 and removed the "boot in DOS mode" option. It also added a new feature called System Restore, allowing the user to set the computer's settings back to an earlier date. Me is also the last DOS-based Windows release which does not include Microsoft Product Activation.

Windows NT family

Windows 7, the next Windows release

The NT family of Windows systems was fashioned and marketed for higher reliability business use, and was unencumbered by any Microsoft DOS patrimony. The first release was MS Windows NT 3.1 (1993, numbered "3.1" to match the consumer Windows version, which was followed by NT 3.5 (1994), NT 3.51 (1995), NT 4.0 (1996), and Windows 2000 (2000). 2000 is the last NT-based Windows release which does not include Microsoft Product Activation. NT 4.0 was the first in this line to implement the "Windows 95" user interface (and the first to include Windows 95’s built-in 32-bit runtimes). Microsoft then moved to combine their consumer and business operating systems with Windows XP, coming in both home and professional versions (and later niche market versions for tablet PCs and media centers); they also diverged release schedules for server operating systems. Windows Server 2003, released a year and a half after Windows XP, brought Windows Server up to date with MS Windows XP. After a lengthy development process, Windows Vista was released toward the end of 2006, and its server counterpart, Windows Server 2008 was released in early 2008. In 2009, Windows 7 and Windows Server 2008 R2 entered beta. Microsoft plans to release Windows 7 in late 2009 or early 2010.

Windows CE, Microsoft’s offering in the mobile and embedded markets, is also a true 32-bit operating system that offers various services for all sub-operating workstations.

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 variously supported PowerPC, DEC Alpha and MIPS R4000, some of which were 64-bit processors, although the operating system treated them as 32-bit processors.

With the introduction of the Intel Itanium architecture, which is referred to as IA-64, Microsoft released new versions of Windows to support it. Itanium versions of Windows XP and Windows Server 2003 were released at the same time as their mainstream x86 (32-bit) counterparts. On April 25, 2005, Microsoft released Windows XP Professional x64 Edition and x64 versions of Windows Server 2003 to support the AMD64/Intel64 (or x64 in Microsoft terminology) architecture. Microsoft dropped support for the Itanium version of Windows XP in 2005. Windows Vista is the first end-user version of Windows that Microsoft has released simultaneously in x86 and x64 editions. Windows Vista does not support the Itanium architecture. The modern 64-bit Windows family comprises AMD64/Intel64 versions of Windows Vista, and Windows Server 2008, in both Itanium and x64 editions. Windows Server 2008 R2 drops the 32-bit version, although Windows 7 does not.

Windows CE

Windows CE (officially known as Windows Embedded), is an edition of Windows that runs on minimalistic computers, like satellite navigation systems, and uncommonly mobile phones. Windows Embedded runs as CE, rather than NT, which is why it should not be mistaken for Windows XP Embedded, which is NT.


The Windows family tree.

Microsoft has taken two parallel routes in its operating systems. One route has been for the home user and the other has been for the professional IT user. The dual routes have generally led to home versions having greater multimedia support and less functionality in networking and security, and professional versions having inferior multimedia support and better networking and security.[citation needed]

The first version of Microsoft Windows, version 1.0, released in November 1985, lacked a degree of functionality and achieved little popularity, and was to compete with Apple’s own operating system.[citation needed] Windows 1.0 is not a complete operating system; rather, it extends 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.[11][12]

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.[13][14] It featured improvements to the user interface and to multitasking capabilities. It received a facelift in Windows 3.1, made generally available on March 1, 1992. Windows 3.1 support ended on December 31, 2001.[15]

In July 1993, Microsoft released Windows NT based on a new kernel. NT was considered to be the professional OS and was the first Windows version to utilize preemptive multitasking.[citation needed]. Windows NT would later be retooled to also function as a home operating system, with Windows XP.

On August 24, 1995, Microsoft released Windows 95, a new, and major, consumer version that made further changes to the user interface, and also used preemptive multitasking. Windows 95 was designed to replace not only Windows 3.1, but also Windows for Workgroups, and MS-DOS. It was also the first Windows operating system to use Plug and Play capabilities. The changes Windows 95 brought to the desktop were revolutionary, as opposed to evolutionary, such as those in Windows 98 and Windows Me. Mainstream support for Windows 95 ended on December 31, 2000 and extended support for Windows 95 ended on December 31, 2001.[16]

The next in the consumer line was Microsoft Windows 98 released on June 25, 1998. It was substantially criticized for its slowness and for its unreliability compared with Windows 95, but many of its basic problems were later rectified with the release of Windows 98 Second Edition in 1999.[citation needed] Mainstream support for Windows 98 ended on June 30, 2002 and extended support for Windows 98 ended on July 11, 2006.[17]

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 implemented a number of new technologies for Microsoft: most notably publicized was "Universal Plug and Play."

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.[18] 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 first "Media Center" edition was released in 2002,[19] with an emphasis on support for DVD and TV functionality including program recording and a remote control. Mainstream support for Windows XP will continue until April 14, 2009 and extended support will continue until April 8, 2014.[20]

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.

On January 30, 2007 Microsoft released Windows Vista. It contains a number of new features, from a redesigned shell and user interface to significant technical changes, with a particular focus on security features. It is available in a number of different editions, and has been subject to some criticism.[citation needed]

Timeline of releases

Release date Product name Current Version / Build Notes Last IE
November 1985 Windows 1.01 1.01 Unsupported -
November 1987 Windows 2.03 2.03 Unsupported -
March 1989 Windows 2.11 2.11 Unsupported -
May 1990 Windows 3.0 3.0 Unsupported -
March 1992 Windows 3.1x 3.1 Unsupported 5
October 1992 Windows For Workgroups 3.1 3.1 Unsupported 5
July 1993 Windows NT 3.1 NT 3.1 Unsupported 5
December 1993 Windows For Workgroups 3.11 3.11 Unsupported 5
January 1994 Windows 3.2 (released in Simplified Chinese only) 3.2 Unsupported 5
September 1994 Windows NT 3.5 NT 3.5 Unsupported 5
May 1995 Windows NT 3.51 NT 3.51 Unsupported 5
August 1995 Windows 95 4.0.950 Unsupported 5.5
July 1996 Windows NT 4.0 NT 4.0.1381 Unsupported 6
June 1998 Windows 98 4.10.1998 Unsupported 6
May 1999 Windows 98 SE 4.10.2222 Unsupported 6
February 2000 Windows 2000 NT 5.0.2195 Extended Support until July 13, 2010[21] 6
September 2000 Windows Me 4.90.3000 Unsupported 6
October 2001 Windows XP NT 5.1.2600 Current for SP2 and SP3 (RTM and SP1 unsupported). 8
March 2003 Windows XP 64-bit Edition 2003 NT 5.2.3790 Unsupported 6
April 2003 Windows Server 2003 NT 5.2.3790 Current for SP1, R2, SP2 (RTM unsupported). 8
April 2005 Windows XP Professional x64 Edition NT 5.2.3790 Current 8
July 2006 Windows Fundamentals for Legacy PCs NT 5.1.2600 Current 8
November 2006 (volume licensing)
January 2007 (retail)
Windows Vista NT 6.0.6001 Current. Version Changed to NT 6.0.6001 with SP1 (February 4, 2008) 8
July 2007 Windows Home Server NT 5.2.4500 Current 8
February 2008 Windows Server 2008 NT 6.0.6001 Current 8
TBA Windows 7 NT 6.1.7000 Beta release 8


Security has been a hot topic with Windows for many years, and even Microsoft itself has been the victim of security breaches.[citation needed] Consumer versions of Windows were 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.[22][23][24]

Windows NT and its successors are designed for security (including on a network) and multi-user PCs, but were not initially designed with Internet security in mind as much since, when it was first developed in the early 1990s, Internet use was less prevalent.[citation needed]

These design issues combined with flawed code (such as buffer overflows) and the popularity of Windows means that it is a frequent target of computer worm and virus writers. 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.[25]

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.[26] 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. As a result, Service Pack 2 for Windows XP, as well as Service Pack 1 for Windows Server 2003, were installed by users more quickly than it otherwise might have been.[27]

Windows Defender

On January 6, 2005, Microsoft released a beta version of Microsoft AntiSpyware, based upon the previously released Giant AntiSpyware. On February 14, 2006, Microsoft 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. Windows XP and Windows Server 2003 users who have genuine copies of Microsoft Windows can freely download the program from Microsoft's web site, and Windows Defender ships as part of Windows Vista.[28]

Third-party analysis

In an article based on a report by Symantec,[29] has described Microsoft Windows as having the "fewest number of patches and the shortest average patch development time of the five operating systems it monitored in the last six months of 2006."[30] And the number of vulnerabilities found in Windows has significantly increased— Windows: 12+, Red Hat + Fedora: 2, Mac OS X: 1, HP-UX: 2, Solaris: 1.

A study conducted by Kevin Mitnick and marketing communications firm Avantgarde in 2004 found that an unprotected and unpatched Windows XP system with Service Pack 1 lasted only 4 minutes on the Internet before it was compromised, and an unprotected and also unpatched Windows Server 2003 system was compromised after being connected to the internet for 8 hours.[31] However, it is important to note that this study does not apply to Windows XP systems running the Service Pack 2 update (released in late 2004), which vastly improved the security of Windows XP. The computer that was running Windows XP Service Pack 2 was not 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.[32] 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.[citation needed]

Windows Lifecycle Policy

Microsoft has stopped releasing updates and hotfixes for many old Windows operating systems, including all versions of Windows 9x,[33] and earlier versions of Windows NT. Windows versions prior to XP are no longer supported, with the exception of Windows 2000, which is currently in the Extended Support Period, that will end on July 13, 2010. Windows XP versions prior to SP2 are no longer supported either. Also, support for Windows XP 64-bit Edition ended after the release of the more recent Windows XP Professional x64 Edition.[citation needed] No new updates are created for unsupported versions of Windows.

Emulation software

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

  • Wine — a free and open source software implementation of the Windows API, allowing one to run many Windows applications on x86-based platforms, including Linux. Wine is technically not an emulator but a "compatibility layer";[34] while an emulator effectively ‘pretends’ to be a different CPU, Wine instead makes use of Windows-style APIs to ‘simulate’ the Windows environment directly.
    • CrossOver — A Wine package with licensed fonts. Its developers are regular contributors to Wine, and focus on Wine running officially supported applications.
    • CedegaTransGaming Technologies' proprietary fork of Wine, designed specifically for running games written for Microsoft Windows under Linux. A version of Cedega known as Cider is used by some video game publishers to allow Windows games to run on Mac OS X. Since wine was licensed under the LGPL Cedega has been unable to port the improvements made to wine to their proprietary codebase.
    • Darwine — A bundling of Wine to the PowerPC Macs running OS X by running wine on top of QEMU. Intel Macs use the same Wine as other *NIX x86 systems.
  • ReactOS — An open-source OS that is intended to run the same software as Windows, originally designed to imitate Windows NT 4.0, now aiming at Windows XP compatibility. It has been in the development stage since 1996.

See also


Further reading:


  1. ^ "The Unusual History of Microsoft Windows". Retrieved on 2007-04-22. 
  2. ^ a b "Operating System Market Share". Hitslink. 
  3. ^ Petzold
  4. ^ Petzold
  5. ^ "Windows Evolution". News. 
  6. ^ "Net Applications OS versions market share". 2009-02. 
  7. ^ "global web stats". W3Counter. 2009-01. 
  8. ^ "report". XiTiMonitor. 
  9. ^ "press release". OneStat. 2008-12-08. 
  10. ^ "Net Applications Trend for 'Windows 95'". 2008-12. 
  11. ^ The Apple vs. Microsoft GUI Lawsuit, 2006,, retrieved on 2008-03-12 
  12. ^ Apple Computer, Inc. v. MicroSoft Corp., 35 F.3d 1435 (9th Cir. 1994),, retrieved on 2008-03-12 
  13. ^ "Chronology of Personal Computer Software". 
  14. ^ "Microsoft Company". 
  15. ^ Windows 3.1 Standard Edition Support Lifecycle
  16. ^ Windows 95 Support Lifecycle
  17. ^ Windows 98 Standard Edition Support Lifecycle
  18. ^ Your top Windows XP questions answered! (Part One)
  19. ^ Paul Thurrott's SuperSite for Windows: A Look at Freestyle and Mira
  20. ^ Windows XP Professional Lifecycle Support
  21. ^ "Windows 2000 Professional Edition Support Lifecycle". Microsoft. May 4, 2005. Retrieved on 2007-03-25. 
  22. ^ not till NT and XP was there multi-user memory protection, and not until Vista was the default user not an admin. UAC msdn
  23. ^ *NIX systems by contrast have always been multi-user, contained true memory management and segmentation, and generally used as a limited privileged user. multics
  24. ^ then UNIX
  25. ^ Schneier, Bruce (June 15, 2005). "Crypto-Gram Newsletter". Counterpane Internet Security, Inc.. Retrieved on 2007-04-22. 
  26. ^ Ryan Naraine (June 8, 2005). "Microsoft's Security Response Center: How Little Patches Are Made". eWeek. Retrieved on 2007-04-22. 
  27. ^ John Foley (October 20, 2004). "Windows XP SP2 Distribution Surpasses 100 Million". InformationWeek. Retrieved on 2007-04-22. 
  28. ^ "Windows Vista: Features". MicroSoft. Retrieved on 2006-07-20. 
  29. ^ "Symantec 11th Internet Security Threat Report, Trends for July–December 6". 
  30. ^ "Report Says Windows Gets The Fastest Repairs". 
  31. ^ "Automated "Bots" Overtake PCs Without Firewalls Within 4 Minutes". Avant Garde. 
  32. ^ "Safety Study" (PDF). Stay Safe Online. Archived from the original on 2005-11-02. 
  33. ^ Ward, Mark (2006-07-11). "Microsoft shuts down Windows 98". BBC. Retrieved on 2009-01-10. 
  34. ^ "Wine". 

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