Microsoft Windows

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.

Versions

See also: List of Microsoft Windows versions

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, mostly because they ran on top of MS-DOS and used it for file system services.^[3] 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. 16-bit Windows versions include Windows 1.0 (1985), Windows 2.0 (1987) and its close relatives, Windows/286-Windows/386.

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, although graphical MS-DOS applications required full screen mode. Also, Windows applications were multi-tasked cooperatively inside one such virtual 8086 environment.

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. 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.

Hybrid 16/32-bit operating systems

With the introduction of the 32-bit Windows for Workgroups 3.11, Windows was able to stop relying on DOS for file management. Leveraging this, Windows 95 introduced Long File Names, reducing the 8.3 filename DOS environment 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. 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 and primitive USB 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 some aspects of Windows 2000 and removed the option boot into DOS mode. It also added a new feature called System Restore, allowing the user to set the computer's settings back to an earlier date.

32-bit operating systems

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). 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.

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 32-bit 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 2003 and Windows Server 2008, in both Itanium and x64 editions.

History

Main article: History of Microsoft Windows

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.

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. 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.^[8][9]

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.^[10][11] 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.^[12]

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.. 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.^[13]

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. Mainstream support for Windows 98 ended on June 30, 2002 and extended support for Windows 98 ended on July 11, 2006.^[14]

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.^[15] 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,^[16] 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.^[17]

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.

Timeline of releases

Main article: Timeline of Microsoft Windows

Security

Worldwide Regional Directors Meeting Feb 1995

Security has been a hot topic with Windows for many years, and even Microsoft itself has been the victim of security breaches. 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. Windows NT and its successors are designed for security (including on a network) and multi-user PCs, but are not designed with Internet security in mind as much since, when it was first developed in the early 1990s, Internet use was less prevalent. 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.^[19]

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.^[20] 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.^[21]

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.^[22]

Third-party analysis

In an article based on a report by Symantec,^[23] internetnews.com 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."^[24] 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.^[25] 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.^[26] 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 Lifecycle Policy

Microsoft has stopped releasing updates and hotfixes for many old Windows operating systems, including all versions of Windows 9x 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. 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";^[27] 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.
  • Cedega — TransGaming Technologies' proprietary fork of Wine, designed specifically for running games written for Microsoft Windows under Linux.
  • 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.
• 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

General:

• Comparison of operating systems
• Comparison of Windows and Linux
• Comparison of Windows versions
• List of operating systems
• Microsoft computers made for Windows

Further reading:

• Architecture of the Windows NT operating system line
• Microsoft Windows topics
• Criticism of Microsoft Windows
• List of Microsoft Windows components
• VisiOn
• Windows Explorer
• Windows Genuine Advantage
• Windows Media
• Windows Startup Process

References

External links

• Official Microsoft Windows Website
• Microsoft Windows History Timeline
• Microsoft Developer Network