Windows XP

Windows XP

File:Microsoft Windows XP logo and wordmark.svg
Screenshot of Windows XP
Developer	Microsoft Corporation
OS family	Microsoft Windows
Source model	Closed source, Shared source
Released to manufacturing	August 24, 2001 (2001-08-24)
General availability	October 25, 2001 (2001-10-25)
Latest release	5.1 (Build 2600: Service Pack 3) / April 21, 2008 (2008-04-21)
Update method	Windows Update Windows Server Update Services (WSUS) System Center Configuration Manager (SCCM)
Platforms	IA-32, x86-64 and Itanium
Kernel type	Hybrid
License	Proprietary commercial software
Preceded by	Windows 2000 (2000) Windows ME (2000)
Succeeded by	Windows Vista (2007)
Support status

Windows XP is a personal computer operating system produced by Microsoft as part of Windows NT family of operating systems. Development of XP began in the late 1990's as "Neptune", an operating system built on the Windows NT kernel which was intended specifically for mainstream consumer use—an updated version of Windows 2000 was also originally planned for the business market. However, in January 2000, both projects were shelved in favor of a single OS codenamed "Whistler", which would serve as a single OS platform for both consumer and business markets. The operating system was released to manufacturing on August 24, 2001, and generally released at for retail sale on October 25, 2001.

The NT-based versions of Windows, which are programmed in C, C++, and assembly, are known for their improved stability and efficiency over the 9x versions of Microsoft Windows. Windows XP presented a significantly redesigned graphical user interface, a change Microsoft promoted as more user-friendly than previous versions of Windows. In an attempt to further ameliorate the "DLL hell" that plagued the past versions of Windows, improved side-by-side assembly technology in Windows XP allows side-by-side installation, registration and servicing of multiple versions of globally shared software components in full isolation. It is also the first version of Windows to use product activation in an effort to reduce software piracy.

Over 400 million copies of Windows XP were in use by January 2006. It was succeeded by Windows Vista in January 2007. Direct OEM and retail sales of Windows XP ceased on June 30, 2008. Microsoft continued to sell Windows XP through their System Builders (smaller OEMs who sell assembled computers) program until January 31, 2009. On April 10, 2012, Microsoft reaffirmed that extended support for Windows XP and Office 2003 would end on April 8, 2014 and suggested that administrators begin preparing to migrate to a newer OS. But on January 17, 2014 Microsoft confirmed that Monthly Microsoft's Malicious Software Removal Tool (MSRT) which aligned with Microsoft's anti-malware engines and signature will remain available until July 14, 2015. XP users can download the software from its website manually. As of 2013, it is the second most popular version of Windows, based on installed user base.

According to web analytics data generated by Net Applications, Windows XP was the most widely used operating system until August 2012, when Windows 7 overtook it. As of February 2014, Windows XP market share is at 29.23%, having decreased almost every month since November 2007 until February 2014, the first month for which statistics are publicly available from Net Applications.

Development

Main article: Development of Windows XP

As "Neptune"

In the late 1990s, initial development of what would become Windows XP was focused on two individual products; "Odyssey", which was reportedly intended to succeed Windows 2000, and "Neptune", which was intended to succeed the MS-DOS-based Windows 98 with a Windows NT-based product designed for consumers. Based off 2000's NT 5.0 kernel, Neptune primarily focused on offering a simplified, task-based interface based around a concept known internally as "activity centers". A number of activity centers were planned, serving as hubs for communications (i.e. email), playing music, managing or viewing photos, searching the internet, and viewing recently used content. A single build of Neptune, 5111 (which was otherwise based on, and still carried the branding of Windows 2000 in places), revealed early work on the activity center concept, with an updated user account interface and graphical login screen, common functions (such as recently used programs) being accessible from a customizable "Starting Places" page (which could be used as either a separate window, or a full-screen desktop replacement).

However, the project, at its current state, proved to be too ambitious. Microsoft would ultimately shelve Bill Gates' 1998 promise that Windows 98; at the WinHEC conference on April 7, 1999, Steve Ballmer announced an updated version of 98 known as Windows Millennium. Microsoft also planned to push back Neptune in favor of an interim, but consumer-oriented NT-based OS codenamed "Asteroid". Concepts introduced by Neptune would influence future Windows products; in Windows ME, the activity center concept was used for System Restore and Help and Support (which both combined Win32 code with an interface rendered using Internet Explorer's layout engine), the hub concept would be expanded on Windows Phone, and Windows 8 would similarly use a simplified user interface running atop the existing Windows shell.

As "Whistler"

In January 2000, shortly after the release of Windows 2000, technology writer Paul Thurrott reported that Microsoft had shelved both Neptune and Odyssey in favor of a new product codenamed Whistler, after Whistler, British Columbia, as many Microsoft employees skied at the Whistler-Blackcomb ski resort. The goal of Whistler was to unify both the consumer and business-oriented Windows lines under a single, Windows NT platform, further stating that "Neptune became a black hole when all the features that were cut from [Windows ME] were simply re-tagged as Neptune features. And since Neptune and Odyssey would be based on the same code-base anyway, it made sense to combine them into a single project". At WinHEC in April 2000, Microsoft officially announced and presented an early build of Whistler, focusing on a new modularized architecture, built-in CD burning, fast user switching, and updated versions of the digital media features introduced by ME. Windows general manager Carl Stork stated that Whistler would be released in both consumer- and business-oriented versions built atop the same architecture, and that there were plans to update the Windows interface to make it "warmer and more friendly".

In June 2000, Microsoft began the technical beta testing process; Whistler was expected to be made available in "Personal", "Professional", "Server", "Advanced Server", and "Datacenter" editions. At PDC on July 13, 2000, Microsoft announced that Whistler would be released during the second half of 2001, and also released the first preview build, 2250. The build notably introduced an early version of a new visual styles system along with an interim theme known as "Professional" (later renamed "Watercolor"), and contained a hidden "Start page" (a full-screen page similar to Neptune's "Starting Places"), and a hidden, early version of a two-column Start menu design. Build 2257 featured further refinements to the Watercolor theme, along with the official introduction of the two-column Start menu, and the addition of an early version of Windows Firewall.

Beta releases

Microsoft released Whistler Beta 1, build 2296, on October 31, 2000. Build 2410 in January 2001 introduced Internet Explorer 6.0 (previously branded as 5.6) and the Windows Product Activation system. Bill Gates dedicated a portion of his keynote at Consumer Electronics Show to discuss Whistler, explaining that the OS would bring "[the] dependability of our highest end corporate desktop, and total dependability, to the home", but also "move it in the direction of making it very consumer-oriented. Making it very friendly for the home user to use." Alongside Beta 1, it was also announced that Microsoft would prioritize the release of the consumer-oriented versions of Whistler over the server-oriented versions in order to gauge reaction, but that they would be both generally available during the second half of 2001 (Whistler Server would ultimately be delayed into 2003). Builds 2416 and 2419 added the File and Transfer Settings Wizard and began to introduce elements of the operating system's final appearance (such as its near-final Windows Setup design, and the addition of new default wallpapers, such as Bliss).

On February 5, 2001, Microsoft officially announced that Whistler would be known as Windows XP, short for "experience". As a compliment, the next version of Microsoft Office was also announced as Office XP. Microsoft stated that the name "[symbolizes] the rich and extended user experiences Windows and Office can offer by embracing Web services that span a broad range of devices." In a press event at EMP Museum in Seattle on February 13, 2001. Microsoft publicly unveiled the new "Luna" user interface of Windows XP. Windows XP Beta 2, build 2462a (which among other improvements, introduced the Luna style), was launched at WinHEC on March 25, 2001.

In April 2001, Microsoft controversially announced that XP would not integrate support for Bluetooth or USB 2.0 on launch, requiring the use of third-party drivers. Critics felt that in the case of the latter, Microsoft's decision had delivered a potential blow to the adoption of USB 2.0, as XP was to provide support for the competing, Apple-developed FireWire standard instead. A representative stated that the company had "[recognized] the importance of USB 2.0 as a newly emerging standard and is evaluating the best mechanism for making it available to Windows XP users after the initial release." The builds prior to and following Release Candidate 1 (build 2505), released on July 5, 2001, and Release Candidate 2 (build 2526, released on July 27, 2001), focused on fixing bugs, acknowledging user feedback, and other final tweaks before the RTM build.

RTM and release

On August 24, 2001, Windows XP, build 2600, was released to manufacturing. During a ceremonial media event at Microsoft Redmond Campus, copies of the RTM build were given to representatives of several major PC manufacturers in briefcases, who then flew off on XP-branded helicopters. While PC manufacturers would be able to release devices running XP beginning on September 24, 2001, XP was expected to reach general, retail availability on October 25, 2001. On the same day, Microsoft also announced the final retail pricing of XP's two main editions, "Home" and "Professional".

In June 2001, Microsoft indicated that it was planning to, in conjunction with Intel and other PC makers, spend at least US$1 billion on marketing and promoting Windows XP.

New and updated features

Main article: Features new to Windows XP

User interface

User interface elements

Default theme	Classic user interface
Updated start menu, now featuring two columns	"Royale" theme of Media Center edition
The "task grouping" feature introduced in Windows XP showing both grouped and individual items

While retaining some similarities to previous versions, Windows XP's interface was overhauled with a new visual appearance, with an increased use of alpha compositing effects, drop shadows, and "visual styles", which completely change the appearance of the operating system. The amount of effects enabled are determined by the operating system by the computer's processing power, and can be enabled or disabled on a case-by-case basis. XP also added ClearType, a new subpixel rendering system designed to improve the appearance of fonts on LCD displays. A new set of system icons were also introduced. The default wallpaper, Bliss, is a photo of a landscape in the Napa Valley outside Napa, California, with rolling green hills and a blue sky with stratocumulus and cirrus clouds.

The Start menu received its first major overhaul on XP, switching to a two-column layout with the ability to list pin and display frequently used applications, recently opened documents, and the traditional cascading "All Programs" menu. The taskbar can now group windows opened by a single application into one taskbar button, with a popup menu listing the individual windows. The notification area also hides "inactive" icons by default. The taskbar can also be "locked" to prevent accidental moving or other changes. A "common tasks" list was added Windows Explorer's sidebar was updated to use a new task-based designs with lists of common actions; the tasks displayed are contextually relevant to the type of content in a folder (i.e. a folder with music displays offers to play all the files in the folder, or burn them to a CD).

System

A new system known as fast user switching was added, which allows users in non-domain environments to save the current state and open applications of their desktop and allows another user to log on without losing that information In an effort to prevent software piracy, XP also introduced Windows Product Activation, which requires that each Windows license be "activated" and tied to a unique ID generated using information from the system's hardware.

A number of enhancements were made to the Windows NT kernel to improve its performance and reliability, which include a more prominent use of prefetching functions to improve start-up and application launch times, and improvements to memory management among other internal changes. Additionally, it also became possible to rollback the installation of an updated device driver, should one not produce desirable results.

Numerous improvements were also made to system administration tools such as Windows Installer, Windows Script Host, Disk Defragmenter, Windows Task Manager, Group Policy, CHKDSK, NTBackup, Microsoft Management Console, Shadow Copy, Registry Editor, Sysprep and WMI

Networking and internet functionality

Windows XP was originally bundled with Internet Explorer 6, Outlook Express 6, Windows Messenger, and MSN Explorer. New networking features were also added to XP, including Internet Connection Firewall, Internet Connection Sharing integration with UPnP, NAT traversal APIs, Quality of Service features, IPv6 and Teredo tunneling, Background Intelligent Transfer Service, extended fax features, network bridging, peer to peer networking, support for most DSL modems, IEEE 802.11 (Wi-Fi) connections with auto configuration and roaming, TAPI 3.1, and networking over FireWire. Remote Assistance and Remote Desktop were also added, which allow users to connect to a computer running Windows XP from across a network or the Internet and access their applications, files, printers, and devices or request help. Improvements were also made to IntelliMirror features such as Offline Files, Roaming user profiles and Folder redirection.

Other features

• DirectX 8.1 upgradeable to DirectX 9.0c
• A number of new features in Windows Explorer including task panes, tiles and filmstrip views, improved sorting and grouping, searching by document categories, customizable infotips, built-in CD burning, AutoPlay, Simple File Sharing and WebDAV mini-redirector.
• Improved imaging features such as Windows Picture and Fax Viewer, improved image handling and thumbnail caching in Explorer
• A number of kernel enhancements and power management improvements
• Faster start-up, (due to improved Prefetch functions) logon, logoff, hibernation and application launch sequences.
• Numerous improvements to increase the system reliability such as improved System Restore, Automated System Recovery, Windows Error Reporting and driver reliability.
• Hardware support improvements such as USB 2.0, FireWire 800, Windows Image Acquisition, Media Transfer Protocol, DualView for multi-monitors and audio improvements.
• Fast user switching,
• The ClearType font rendering mechanism, which is designed to improve text readability on liquid crystal display (LCD) and similar monitors, especially laptops.
• Side-by-side assemblies and registration-free COM
• Improved media features in Windows Media format runtime, Windows Media Player, Windows Movie Maker, TV/video capture and playback technologies, Windows Media Encoder and introduction of Windows Media Center
• General improvements to international support such as more locales, languages and scripts, MUI support in Terminal Services, improved IMEs and National Language Support, Text Services Framework
• Improved application compatibility and shims compared to Windows 2000
• Updated accessories and games.

Users in British schools observed the improved ease of use and advanced capabilities – comparing the former to RISC OS and Mac OS, and the latter to Unix.

Removed features

Main article: List of features removed in Windows XP

Some of the programs and features that were part of the previous versions of Windows did not make it to Windows XP. CD Player, DVD Player and Imaging for Windows are removed as Windows Picture and Fax Viewer, Windows Media Player and Windows shell take over their duties. NetBEUI and NetDDE are deprecated and are not installed by default. DLC and AppleTalk network protocols are removed. Plug-and-play–incompatible communication devices (like modems and network interface cards) are no longer supported.

Service Pack 2 and Service Pack 3 also remove features from Windows XP but to a less noticeable extent. For instance, Program Manager and support for TCP half-open connections are removed in Service Pack 2. Energy Star logo and the address bar on taskbar are removed in Service Pack 3.

Editions

Main article: Windows XP editions

Diagram representing the main editions of Windows XP. It is based on the category of the edition (grey) and codebase (black arrow).

Windows XP was released in two major editions on launch; Home Edition, and Professional. Both editions were made available at retail as pre-loaded software on new computers, and in boxed copies. Boxed copies were sold as "Upgrade" or "Full" licenses; the "Upgrade" versions were slightly cheaper, but require an existing version of Windows to install. The "Full" version could be installed on systems without an operating system or existing version of Windows. Both versions of XP were aimed towards different markets; Home Edition is explicitly intended for consumer use and disables or removes certain advanced and enterprise-oriented features present on Professional, such as the ability to join a Windows domain, Internet Information Services, and Multilingual User Interface. Additionally, users could not directly upgrade to XP Home Edition from Windows NT 4.0 or 2000, although users could upgrade to either variant of XP from Windows 98 or ME. Windows' software license agreement for pre-loaded licenses allows the software to be "returned" to the OEM for a refund if the user does not wish to use it. Despite the refusal of some manufacturers to honor the entitlement, it has been enforced by courts in some countries.

Two specialized variants of XP were introduced in 2002 for certain types of hardware, exclusively through OEM channels as pre-loaded software. Windows XP Media Center Edition was initially designed for high-end home theater PCs with TV tuners (marketed under the term "Media Center PC"), offering expanded multimedia functionality, an electronic program guide, and digital video recorder (DVR) support through the Windows Media Center application. Microsoft also unveiled Windows XP Tablet PC Edition, which contains additional pen input features, and is optimized for mobile devices meeting its Tablet PC specifications. Two different 64-bit editions of XP were made available; the first, Windows XP 64-Bit Edition, was intended for IA-64 (Itanium) systems; as IA-64 usage declined on workstations in favor of AMD's x86-64 architecture (which was supported by the later Windows XP Professional x64 Edition), the Itanium version was discontinued in 2005.

Microsoft also targeted emerging markets with the 2004 introduction of Windows XP Starter Edition, a special variant of Home Edition intended for low-cost PC's. The OS is primarily aimed at first-time computer owners (particularly in developing countries); containing heavy localization (including wallpapers and screen savers incorporating images of local landmarks), and a "My Support" area which contains video tutorials on basic computing tasks. It also removes certain "complex" features, and does not allow users to run more than three applications at a time. After a pilot program in India and Thailand, Starter was released in other emerging markets throughout 2005. In 2006, Microsoft also unveiled the FlexGo initiative, which would also target emerging markets with subsidized PCs on a pre-paid, subscription basis.

As the result of unfair competition lawsuits in Europe and South Korea, which both alleged that Microsoft had improperly leveraged its status in the PC market to favor its own software, Microsoft was forced to release special versions of XP in these markets that excluded certain applications. In March 2004, after the European Commission fined Microsoft €497 million (US$603 million), Microsoft was forced to release "N" versions of XP that excluded Windows Media Player, encouraging users to pick and download their own media player software. As it is sold at the same price as the version with Windows Media Player included, certain OEMs (such as Dell, who offered it for a short period, along with Hewlett-Packard, Lenovo and Fujitsu Siemens) chose not to offer it. Consumer interest has been low, with roughly 1,500 units shipped to OEMs, and no reported sales to consumers. In December 2005, the Korean Fair Trade Commission ordered Microsoft to make available editions of Windows XP and Windows Server 2003 that do not contain Windows Media Player or Windows Messenger. The "K" and "KN" editions of Windows XP were released in August 2006, and are only available in English and Korean, and also contain links to third-party instant messenger and media player software.

Service packs

Three service packs were released for Windows XP, containing various bug fixes and the addition of certain features. Each service pack is a superset of all previous service packs and patches so that only the latest service pack needs to be installed, and also includes new revisions.

Service Pack 1

File:Windows XP - Program Access and Defaults.png

Set Program Access and Defaults was added in Service Pack 1.

Service Pack 1 (SP1) for Windows XP was released on September 9, 2002. It contained over 300 minor, post-RTM bug fixes, along with all security patches released since the original release of XP. SP1 also added USB 2.0 support, Microsoft Java Virtual Machine, .NET Framework support, and support for technologies used by the then-upcoming Media Center and Tablet PC editions of XP. The most significant change on SP1 was the addition of Set Program Access and Defaults, a settings page which allows users and OEMs to set default programs for certain types of activities (such as media players or web browsers) and disable access to bundled, Microsoft programs (such as Internet Explorer or Windows Media Player). This was added as part of the company's settlement in United States v. Microsoft Corp., which stated that Microsoft would allow users to "enable or remove access to each Microsoft Middleware Product or Non-Microsoft Middleware Product by displaying or removing icons, shortcuts, or menu entries on the desktop or Start menu, or anywhere else in a Windows Operating System Product where a list of icons, shortcuts, or menu entries for applications are generally displayed."

On February 3, 2003, Microsoft released Service Pack 1a (SP1a). This release removed Microsoft Java Virtual Machine as a result of a lawsuit with Sun Microsystems.

Service Pack 2

Windows Security Center was added in Service Pack 2.

Service Pack 2 (SP2) was released on August 25, 2004, with an emphasis on security. Unlike the previous service pack, SP2 added new functionality to Windows XP, such as WPA encryption compatibility and improved Wi-Fi support (with a wizard utility), a pop-up ad blocker for Internet Explorer 6, and partial Bluetooth support.

Service Pack 2 also added new security enhancements (codenamed "Springboard"), which included a major revision to the included firewall that was renamed to Windows Firewall and became enabled by default, Data Execution Prevention gained hardware support in the NX bit that can stop some forms of buffer overflow attacks. Also raw socket support is removed (which supposedly limits the damage done by zombie machines). Additionally, security-related improvements were made to e-mail and web browsing. Service Pack 2 also added Security Center, an interface which provides a general overview of the system's security status, including the state of the firewall and automatic updates. Third-party firewall and antivirus software can also be monitored from Security Center.

In August 2006, Microsoft released updated installation media for Windows XP and Windows Server 2003 SP2 (SP2b) to contain a patch that requires ActiveX controls to require manual activation in accordance with a patent held by Eolas. Microsoft has since licensed the patent, and released a patch reverting the change in April 2008. In September 2007, another minor revision known as SP2c was released for XP Professional, extending the number of available product keys for the operating system to "support the continued availability of Windows XP Professional through the scheduled system builder channel end-of-life (EOL) date of January 31, 2009."

Service Pack 3

Windows XP Service Pack 3 (SP3) was released to manufacturing on April 21, 2008, and to the public via both the Microsoft Download Center and Windows Update on May 6, 2008.

It began being automatically pushed out to Automatic Update users on July 10, 2008. A feature set overview which details new features available separately as stand-alone updates to Windows XP, as well as backported features from Windows Vista, has been posted by Microsoft. A total of 1,174 fixes have been included in SP3. Service Pack 3 can be installed on systems with Internet Explorer versions 6, 7, or 8. Internet Explorer 7 and 8 are not included as part of SP3. Service Pack 3 is not available for the 64 bit version of Windows XP.

New features in Service Pack 3

• NX APIs for application developers to enable Data Execution Prevention for their code, independent of system-wide compatibility enforcement settings
• Turns black hole router detection on by default
• Support for SHA-2 signatures in X.509 certificates
• Network Access Protection client
• Group Policy support for IEEE 802.1X authentication for wired network adapters.
• Credential Security Support Provider
• Descriptive Security options in Group Policy/Local Security Policy user interface
• An updated version of the Microsoft Enhanced Cryptographic Provider Module (RSAENH) that is FIPS 140-2 certified (SHA-256, SHA-384 and SHA-512 algorithms)
• Installing without requiring a product key during setup for retail and OEM versions

Previously released updates

Service Pack 3 also incorporated several previously released key updates for Windows XP, which were not included up to SP2, including:

• Windows Imaging Component
• IPSec Simple Policy Update for simplified creation and maintenance of IPSec filters
• Background Intelligent Transfer Service (BITS) 2.5
• MSXML 6.0 SP2 and XMLLite
• Microsoft Management Console 3.0
• Credential Roaming service (Digital Identity Management Service) update
• Remote Desktop Protocol 6.1
• Peer Name Resolution Protocol 2.1
• Network Diagnostics update
• WPA2 Update (KB893357)
• Windows Script 5.7
• Windows Installer 3.1 v2
• Wireless LAN API (KB918997)
• Improvements made to Windows Management Instrumentation in Windows Vista to reduce the possibility of corruption of the WMI repository.

Service Pack 3 contains updates to the operating system components of Windows XP Media Center Edition (MCE) and Windows XP Tablet PC Edition, and security updates for .NET Framework version 1.0, which is included in these editions. However, it does not include update rollups for the Windows Media Center application in Windows XP MCE 2005. SP3 also omits security updates for Windows Media Player 10, although the player is included in Windows XP MCE 2005. The Address Bar DeskBand on the Taskbar is no longer included due to legal restrictions.

System requirements

System requirements for Windows XP Home Edition and Professional are as follows:

	Minimum	Recommended
Processor	233 MHz[1]	At least 300 MHz
Memory	64 MB of RAM[2]	At least 128 MB of RAM
Video adapter and monitor	Super VGA (800 x 600) or higher resolution
Hard drive disk free space	1.5 GB or higher additional 661 MB for Service Pack 1 and 1a additional 1.8 GB for Service Pack 2 and additional 900 MB for Service Pack 3
Optical drive	CD-ROM drive (Only to install from CD-ROM media)
Input devices	Keyboard, Microsoft Mouse or a compatible pointing device
Sound	Sound card and Speakers or headphones
^1 Even though this is Microsoft's stated minimum processor speed for Windows XP, it is possible to install and run the operating system on early IA-32 processors such as a P5 Pentium without MMX instructions. Windows XP is not compatible with processors older than Pentium (such as 486) because it requires CMPXCHG8B instructions. ^2 A Microsoft TechNet paper from Summer 2001 (before Windows XP's actual release), states that: "A computer with 64 MB of RAM will have sufficient resources to run Windows XP and a few applications with moderate memory requirements." (Emphasis added.) These were said to be office productivity applications, e-mail programs, and web browsers (of the time). With such a configuration, user interface enhancements and fast user switching are turned off by default. For comparable workloads, 64 MB of RAM was then regarded as providing an equal or better user experience on Windows XP with similar settings than it would with Windows ME on the same hardware. In a later section of the paper, superior performance over Windows ME was noted with 128 MB of RAM or more, and with computers that exceed the minimum hardware requirements.

System requirements for Windows XP Professional x64 Edition are as follows:

• Processor: x86-64 processor;
• Memory: At least 256 MB of RAM;
• Video adapter and monitor: Super VGA (800 x 600) or higher resolution;
• Hard drive disk free space: At least 1.5 GB;
• Optical drive: CD-ROM drive;
• Input devices: Keyboard; Microsoft Mouse or compatible pointing device;
• Sound: Sound card; Speakers or headphones;

System requirements for Windows XP 64-Bit Edition are as follows:

• Processor: Intel Itanium 733 MHz (Recommended: Intel Itanium 800 MHz or better);
• Memory: At least 1 GB of RAM;
• Video adapter and monitor: Super VGA (800 x 600) or higher resolution;
• Hard drive disk free space: At least 6 GB;
• Optical drive: CD-ROM drive;
• Input devices: Keyboard; Microsoft Mouse or compatible pointing device;
• Sound: Sound card; Speakers or headphones;

Physical memory limits

Maximum limits on physical memory (RAM) that Windows XP can address vary depending on both the Windows version and between 32-bit and 64-bit versions. The following table specifies the maximum physical memory limits supported:

Physical memory limits in each Windows XP edition

Windows XP edition	Maximum RAM supported
Starter	512 MB
Home	4 GB
Media Center
Tablet PC
Professional
Professional x64	128 GB
Professional 64-bit (Itanium)

Processor limits

The maximum total number of logical processors in a PC that Windows XP supports is: 32 for 32-bit; 64 for 64-bit.

The maximum number of physical processors in a PC that Windows XP supports is: 2 for Professional; and 1 for the Home Edition.

Other limits

Windows XP is designed to be installed to and booted from a...

• PC wherein its firmware must use either legacy BIOS or UEFI with CSM enabled.
• hard disk drive wherein its partition mapping scheme must use MBR instead of GUID Partition Table.

Support lifecycle

Support for Windows XP Home edition and Professional edition without a service pack ended on September 30, 2005. Windows XP Service Pack 1 and 1a were retired on October 10, 2006 and Windows XP Service Pack 2 reached end of support on July 13, 2010, almost six years after its general availability.

The company stopped general licensing of Windows XP to OEMs and terminated retail sales of the operating system on June 30, 2008, 17 months after the release of Windows Vista. However, an exception was announced on April 3, 2008, for OEMs installing to ultra low-cost PCs (ULCPCs) until one year after the availability of Windows 7 (that is, until October 22, 2010).

On April 14, 2009, Windows XP and its family of operating systems reached the end of their mainstream support period and entered the extended support phase as it marks the progression of the legacy operating system through the Microsoft Support Lifecycle Policy. During the extended support phase, Microsoft continues to provide security updates every month for Windows XP; however, free technical support, warranty claims, and design changes are no longer being offered. Extended support will end on April 8, 2014—after which no more security patches or new support information will be provided for free. However, according to Gregg Keizer from Computerworld, "critical patches" will still be created, and made available only to customers subscribing to a paid "Custom Support". While many organizations did not upgrade from XP due to the poor reception of Vista, Microsoft has since recommended that they migrate to newer versions of Windows due to the impending end of support. Normally Microsoft products have a support life cycle of 10 years.

As the end of extended support approached, Microsoft began to warn users and organizations of the risks of remaining on XP and not migrating to newer versions such as Windows 7 or 8, suggesting that attackers could reverse engineer security patches for newer versions of Windows and use them to target XP vulnerabilities, considering them to be "permanent zero-day exploits". In January 2014, it was estimated that more than 95% of the 3 million automated teller machines in the world were still running Windows XP. Plans were being made by several ATM vendors and their customers to migrate to Windows 7-based systems over the course of 2014.

On March 8, 2014 Microsoft will begin a monthly notification through Windows Update to warn remaining users of the end-of-support date upon log in. The notification will trigger every month on the 8th to remind users, although the notice can be turned off.

On April 8, 2014, Microsoft will make the last set of updates and fixes for Windows XP and will deliver them via Windows Update.

A Microsoft spokesperson confirmed that there are no current plans to remove existing Windows XP security updates from Windows Update after end of support on April 8, 2014.

China has been strongly against the Windows XP end of support on April 8, 2014. Computer scientist Ni Guangnan at the Chinese Academy of Sciences claimed adopting Windows 8 would leave users open to security threats. Additionally, Beijing said pushing users to a newer operating system could harm its Anti-Piracy efforts.

Downgrade rights

Customers licensed for use of Windows 8 Enterprise are generally licensed for Windows 8 Pro, which may be downgraded to Windows XP Professional. End users of licenses of Windows 7 acquired through OEM or volume licensing may downgrade to the equivalent edition of Windows XP. End users of licenses of Windows Vista Business or Ultimate acquired through OEM have rights to downgrade to Windows XP Professional. Customers licensed for use of Windows Vista Enterprise are licensed for Windows Vista Business and Windows Vista Business can be downgraded to Windows XP Professional.

Market share

According to web analytics data generated by Net Applications, Windows XP is currently the second most-used OS with a market share of 28.98%. It has held the number two spot since July 2012.

According to web analytics data generated by StatOwl, Windows XP has a 27.82% market share as of November 2012, having dropped to second place in October 2011.

According to web analytics data generated by W3Schools, from September 2003 to July 2011, Windows XP was the most widely used operating system for accessing the w3schools website, which they claim is consistent with statistics from other websites. As of September 2013, Windows XP market share is at 13.5% after having peaked at 76.1% in January 2007.

See also

• Comparison of operating systems
• History of operating systems
• List of operating systems
• Comparison of Windows Vista and Windows XP

Further reading

• Joyce, Jerry; Moon, Marianne (2004). Microsoft Windows XP Plain & Simple. Microsoft Press. ISBN 978-0-7356-2112-1.

External links

External videos
Is Windows XP Good Enough?, Microsoft

• Windows XP Help & How-to
• Microsoft Windows XP Reviewers Guide – August 2001 (PDF format)
• Windows XP Memory Limits
• Windows XP Service Pack 3 Network Installation Package for IT Professionals and Developers (Full Offline Installer). If installing from Windows XP without service pack, its service pack 1, 1a, or 2 must be installed first.
• Windows XP Service Pack 2 Network Installation Package for IT Professionals and Developers (Full Offline Installer).
• Windows XP service pack 1 (Full offline installer).
• Windows XP end of support in April 8, 2014: Three more questions answered.