Windows XP Professional x64 Edition

Windows XP Professional
x64 Edition
	Windows XP logo
	File:Windows XP x64.jpg A Windows XP x64 desktop
Developer	Microsoft
OS family	Windows NT
Working state	Current
Source model	Shared source
Latest release	RTM / April 25, 2005
Kernel type	Hybrid kernel
Default; user interface	Graphical User Interface
License	Microsoft EULA
Official website	Windows XP Professional x64 Edition

Microsoft Windows XP Professional x64 Edition released on April 25, 2005 by Microsoft is a variation of the typical 32-bit Windows XP operating system for x86 personal computers.

Windows XP Professional x64 Edition is based upon Windows Server 2003 SP1 (build 5.2.3790.1830), as that was the latest version of Microsoft Windows during the operating system's development, but takes Windows XP as its name. It is designed to use the expanded 64-bit memory address space provided by the AMD64 architecture; Intel refers to its implementation of the technology as EM64T.

The primary benefit of moving to 64-bit is the increase in the maximum allocatable system memory (RAM). Windows XP 32-bit is limited to a total of 4 GB, which is equally divided between Kernel and application usage. Windows XP x64 can support much more memory; although the theoretical memory limit a 64-bit computer can address is about 18 exabytes (18 billion gigabytes), Windows XP x64 is currently limited to 128 GB ( $2^{37}$ bytes) of physical memory and 16 TB ( $2^{44}$ bytes) of virtual memory. Microsoft claims this limit will be increased as hardware capabilities improve. In practice, most motherboards compatible with 64-bit processors do not support anywhere close to the maximum limit, and often retain the 4 GB limit.

The “x64 Edition” is the current edition of Windows XP 64bit.

Compatibility with 32-bit applications

Windows XP x64 Edition uses a technology named WOW64, which permits the execution of 32-bit x86 applications. It was first employed in Windows XP 64-bit Edition, but then reused for the “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 IA-64 (Itanium) architecture, WOW64 was required to translate 32-bit x86 instructions into their 64-bit IA-64 equivalents—which in some cases were implemented in quite different ways—so that the processor could execute them.

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 application cannot link against a 32-bit library (DLL) and similarly a 32-bit application cannot link against a 64-bit library. This may lead to the need for library developers to provide both 32- and 64-bit binary versions of their libraries. Windows XP x64 Edition includes both 32- and 64-bit versions of Internet Explorer, in order to allow for the possibility that some third-party browser plugins or ActiveX controls may not yet be available in 64-bit versions.

Older 32-bit drivers and services are not supported by 64-bit Windows, but video and audio codecs such as XviD or OggDS (which are in fact 32-bit DLLs), are supported as long as the media player that uses them is 32-bit as well.

Compatibility with other applications

Unlike prior versions of the Windows NT line, 64-bit Windows versions do not include NTVDM so there is no support for the execution of MS-DOS, POSIX, OS/2 1.x and 16-bit Windows applications, although there are 3rd-party software emulators such as DOSBox that can be used to run DOS programs.

Another solution is to use virtualization software such as VMware or VirtualPC to run other versions of Windows or MS-DOS. DOSBox will also allow 16-bit Windows applications to run by running Windows 3.1 on the emulator [1]

Known issues

Although the future of computing is in 64-bit OSes, there are still some common issues that have to be dealt with when installing such a system.

Driver compatibility - some hardware companies have yet to write 64-bit drivers for their products.
- Resolution - wait and download an updated driver when one becomes available, upgrade the device or do not use the device.
32-bit (currently most) Windows Explorer extensions fail to work (due to the fact that 32-bit programs cannot interface with 64-bit DLLs and vice versa). This is, for example, the context-menu options from things such as zip utilities and things such as icon overlays.
- Resolution - context-menu commands that only involve running a command on a given file type can be manually added using regedit.
- Resolution - simple context-menu commands that may appear on any file type can be added to the "Send To" menu (a simple solution).
- Resolution - the 32-bit version of Explorer is available and can still be used. One method is to make a shortcut to: "%windir%\syswow64\explorer.exe /separate,C:\" (no quotes).
  - Note - it is possible to use the 32-bit version of Explorer as the default shell, but it will crash when attempting to use removable devices (such as USB flash drives).
- Resolution - Many applications are being updated to 64-bit versions. Applications that rely on Explorer extensions are under additional pressure to do so. Simply wait for (or locate) a new version (or alternate program).
16-bit application components cannot run.
- Resolution - use a dual-boot system, or run a virtualized 32-bit or 16-bit version of Windows. Most old games are best played using DOSBox.

Miscellaneous

During the initial development phases (2003–2004), Windows XP Professional x64 Edition was named Windows XP 64-bit Edition for x86 Extended systems and later, Windows XP 64-bit Edition for Extended systems, as opposed to 64-bit Edition for Itanium systems.

Because of their lineage to Windows Server 2003, Windows XP Professional x64 Edition (along with Windows XP 64-bit Edition Version 2003) are the only versions of Windows XP to ship with IIS 6.0 (all other versions of XP have IIS 5.1).

External links

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