Windows XP Professional x64 Edition is an edition of Windows XP that supports the x86-64 architecture, released alongside the x86-64 versions of Windows Server 2003 on April 25, 2005. It is designed to use the expanded 64-bit memory address space provided by the x86-64 64-bit extensions to the x86 IA-32 architecture, which was implemented by AMD as "AMD64", found in AMD's Opteron, Athlon 64 chips (and in selected Sempron processors), and implemented by Intel as "Intel 64" (formerly known as IA-32e and EM64T), found in some of Intel's Pentium 4 and most of Intel's later chips since the Core series.

Windows XP Professional x64 Edition uses the same kernel and code tree as Windows Server 2003 and is serviced by the same service packs. However, it includes client features of Windows XP such as System Restore, Windows Messenger, Fast User Switching, Welcome Screen, Security Center and games, of which Windows Server 2003 does not have.

During the initial development phases (2003–2004), Windows XP Professional x64 Edition was named Windows XP 64-Bit Edition for 64-Bit Extended Systems and later as Windows XP 64-Bit Edition for Extended Systems, as opposed to 64-Bit Edition for Itanium Systems for Windows XP 64-Bit Edition, as the latter was designed for the IA-64 (Itanium) architecture.

Features

Windows XP Professional x64 Edition offers a number of new and updated features not found in the main 32-bit x86 versions of Windows XP:

End-user

  • Internet Information Services (IIS) version 6.0, the same version that was included in Windows Server 2003, is included with Windows XP Professional x64 Edition. All other 32-bit editions of Windows XP have IIS v5.1.
  • Windows Media Player version 10, the version that came with Windows Server 2003 Service Pack 1, is included with Windows XP Profesional x64 Edition. Windows XP Professional for x86 originally shipped with Windows Media Player version 8 from RTM to Service Pack 1 and later came with Windows Media Player 9 from Service Pack 2 onwards, with Windows XP Media Center Edition 2005 receiving Windows Media Player 10. Windows Media Player 11 is available for x86 versions of Windows XP Service Pack 2 or later.
  • Internet Protocol Security (IPsec) features and improvements made in Windows Server 2003 were included with Windows XP Professional x64 Edition.
  • Shadow Copy, a feature that automatically creates daily backups of files and folders, was first introduced in Windows Server 2003 and is available in Windows XP Professional x64 Edition.
  • Remote Desktop Services supports Unicode keyboard input, client-side time-zone redirection, GDI+ rendering primitives for improved performance, FIPS encryption, fallback printer driver, auto-reconnect and new Group Policy settings.
  • Files and Settings Transfer Wizard supports migrating settings from both 32-bit and 64-bit Windows XP PCs.

Core

Windows XP Professional x64 Edition is based on the Windows Server 2003 kernel and codebase, which is newer than 32-bit Windows XP (by about two years) and has improvements to enhance scalability. It also introduces Kernel Patch Protection (also known as PatchGuard) to improve security by helping to eliminate rootkits.

Advantages

The primary benefit of moving to 64-bit is the increase in the maximum allocatable random-access memory (RAM). 32-bit editions of Windows XP are limited to a total of 4 gigabytes. Although the theoretical memory limit of a 64-bit computer is about 16 exabytes (17.1 billion gigabytes), Windows XP Professional x64 Edition is limited to 128GB of physical memory and 16 terabytes of virtual memory.

Windows XP Professional x64 Edition also offers a number of benefits/advantages over the main 32-bit x86 versions of Windows XP:

  • Supports up to two physical CPUs (in separate physical sockets) and up to 64 logical processors (i.e. cores or threads on a single CPU). Windows XP Professional for x86 supported up to two physical CPUs but is limited to a maximum of 32 logical processors.
  • Supports GPT-partitioned disks for data volumes (but not bootable volumes) after SP1, which allows disks greater than 2TB to be used as a single GPT partition for storing data.
  • Allows for faster encoding of audio or video, higher video game performance and faster 3D rendering than with 32-bit versions of Windows XP, in 64-bit optimized software.
  • Immunity from certain types of viruses and malware targeted at 32-bit versions of Windows XP, as most system files are 64-bit.

Disadvantages/limitations

There are some limitations which apply to Windows XP Professional x64 Edition:

  • Only 64-bit drivers are supported.
  • No native support for Type 1 fonts.
  • IEEE 1394 (FireWire) audio is not supported.
  • Hibernation is not supported if the RAM is greater than 4GB. This would later be resolved by Windows 7.
  • EFI and/or UEFI are not supported. A BIOS with Advanced Configuration and Power Interface (ACPI) is required.
  • Only English or Japanese are provided as native display languages. Chinese, French, German, Italian, Japanese, Korean, Spanish and Swedish are available as Multilingual User Interface (MUI) packs for the English version.
  • Additionally, the extra registers of the x86-64 architecture can cause a slight decrease in performance with certain applications compared to the same application compiled in 32-bit only x86 code running on 32-bit versions of Windows XP.

Software compatibility

Windows XP Professional x64 Edition uses a technology named Windows-on-Windows 64-bit (WoW64), which permits the execution of 32-bit software. It was first used in Windows XP 64-bit Edition (for Itanium architecture). Later, it was adopted for x64 editions of Windows XP and Windows Server 2003.

Since the x86-64 architecture includes hardware-level support for 32-bit instructions, WoW64 simply switches the process between 32- and 64-bit modes. As a result, x86-64 architecture microprocessors suffer no performance loss when executing 32-bit Windows applications. On the Itanium architecture, WoW64 was required to translate 32-bit x86 instructions into their 64-bit Itanium equivalents—which in some cases were implemented in quite different ways—so that the processor could execute them. All 32-bit processes are shown with *32 in the task manager, while 64-bit processes have no extra text present.

Although 32-bit applications can be run transparently, the mixing of the two types of code within the same process is not allowed. A 64-bit program cannot use a 32-bit dynamic-link library (DLL) and similarly a 32-bit program cannot use a 64-bit DLL. This may lead to the need for library developers to provide both 32-bit and 64-bit binary versions of their libraries. Specifically, 32-bit shell extensions for Windows Explorer fail to work with 64-bit Windows Explorer. Windows XP x64 Edition ships with both 32-bit and 64-bit versions of Windows Explorer. The 32-bit version can become the default Windows Shell. Windows XP x64 Edition also includes both 32-bit and 64-bit versions of Internet Explorer 6, so that users can still use browser extensions or ActiveX controls that are not available in 64-bit versions.

Only 64-bit drivers are supported in Windows XP x64 Edition, but 32-bit codecs are supported as long as the media player that uses them is 32-bit. A similar case can be found on both versions of Windows XP 64-bit Edition for Itanium. Despite this, third-party replacements such as OTVDM/WineVDM (based on MAME's i386 emulation and the 16-bit portion of the popular Windows compatibility layer, Wine) can allow MS-DOS and 16-bit Windows applications to run on Windows XP Professional x64 Edition and later 64-bit versions of Windows.

  • With the removal of NTVDM and Windows on Windows, COMMAND.COM, a command interpreter exclusive to MS-DOS and Windows 9x, was removed.
  • Some old 32-bit programs use 16-bit installers which do not run; however, replacements for 16-bit installers such as ACME Setup versions 2.6, 3.0, 3.01, 3.1 and InstallShield 5.x are hardcoded into WoW64 to mitigate this issue. This is true for later 64-bit versions of Windows.
  • Program Manager was removed and replaced with Windows Explorer. The executable is still present, but it was replaced with a compatibility stub that redirects to Explorer. The executable itself would not be removed entirely until Windows Vista.
  • Win32 console programs (including Command Prompt) can no longer run in full-screen text mode. This applies to later versions of Windows since Windows Vista, as it is unsupported by WDDM drivers (Windows 10 later brought back full-screen mode to console programs, however this uses the native Windows rendering subsystem instead of text mode).
  • Media Bar, which replaced the Radio Toolbar in Internet Explorer 6, was removed.
  • The Web Extender Client component for Web Folders (WebDAV) was not included.
  • Spell checking in Outlook Express was removed.

Service packs

The RTM version of Windows XP Professional x64 Edition was built from the Windows Server 2003 Service Pack 1 codebase, and because of this, its service packs are also developed separately. For the same reason, Service Pack 2 for Windows XP x64 Edition, released on March 13, 2007, is not the same as Service Pack 2 for 32-bit versions of Windows XP. Extended support lasted until April 8, 2014, in line with all other Windows XP editions. In May 2019, an emergency patch was released to address a critical code execution vulnerability in Remote Desktop Services which can be exploited in a similar way as the WannaCry vulnerability.

Microsoft announced in July 2019 that the Microsoft Internet Games services on Windows XP and Windows Me would end on July 31, 2019 (and for Windows 7 on January 22, 2020). Others, such as Steam, had done the same, ending support for Windows XP and Windows Vista in January 2019.

In 2020, Microsoft announced that it would disable the Windows Update service for SHA-1 endpoints for older Windows versions. Since Windows XP Professional x64 Edition did not get an update for SHA-2, Windows Update Services are no longer available on the OS as of late July 2020. As of March 2024, many of the old updates for Windows XP Professional x64 Edition are available on the Microsoft Update Catalog. A third-party tool named Legacy Update allows previously released updates for Windows XP Professional x64 Edition to be installed from the Update Catalog.

References

Further reading

ca:Windows XP#64 bits