Windows XP Professional x64 Edition
|
|
Windows XP Professional 64-bit Edition released on April 25 2005 by Microsoft is a variation of the typical 32-bit Windows XP operating system. It is designed to use 64-bit memory addresses which increases the maximum allowable system memory (RAM) past the 32-bit limit of 4 GB, though it is currently limited to 128 GB (237) of physical RAM and 16 TB (244) of virtual RAM. It is currently only available for sale as an OEM product.
| Contents |
Compatibility with 32-bit applications
Windows XP 64-bit Edition uses a technology named WOW64, to allow it to run 32-bit applications using the IA32 instruction set. This consists of:
- Wow64.dll - provides the core emulation services such as data type conversion and an interface to the Windows NT kernel
- Wow64win.dll - provides a wrapper for the majority of the Win32 API
- Wow64cpu.dll - provides for switching the processor between 32-bit and 64-bit modes
Since the AMD64 architecture includes hardware support for 32-bit execution, WOW64 can just simply switch the process between 32-bit and 64-bit modes. However, on the IA64 architecture, WOW64 has to translate 32-bit instructions into 64-bit that the processor can execute. This means the AMD64 based processors are much more efficient at running 32-bit applications than IA64 based processors.
Although 32-bit applications can be transparently run, the mixing of the two types of code within the same process is not possible. A 64-bit application cannot load a 32-bit DLL into its process space, and similarly a 32-bit application cannot load a 64-bit DLL into its process space. This may lead to the need for DLL and COM developers to provide their libraries in both 32-bit and 64-bit editions, in order to accomodate being loaded by an application of either bitness. Windows XP 64-bit Edition includes both a 32-bit and a 64-bit edition 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 a 64-bit version. 32-bit drivers are not supported by Windows XP 64-bit Edition, so the users will have to wait until all their hardware is supported by the hardware vendor with 64-bit drivers [1] (http://www.microsoft.com/windowsxp/64bit/upgrade/default.mspx).
The WOW64 subsystem also redirects the following services when dealing with 32-bit applications:
- Windows Registry - 32-bit applications see a different version of the registry to ensure compatibility between DLL and COM object registrations in 32 and 64-bit modes. WOW64 further provides a registry reflector that intelligently incorporates safe parts of the 32-bit registry tree with the main (64-bit) registry.
- File System Redirection - the directory "%systemroot%\System32" is used by the 64-bit operating system for DLL files. WOW64 transparently redirects 32-bit requests for this directory to the "%systemroot%\SysWOW64" directory, where 32-bit DLLs are stored.
Compatibility with 16-bit applications
Unlike other versions of Windows XP, Windows XP Professional 64-bit Edition does not support the execution of 16-bit Windows or DOS code.
External links
- Microsoft.com - Windows XP Professional 64-bit Edition Home Page (http://www.microsoft.com/windowsxp/64bit/default.mspx)
- PlanetAMD64.com - Forums, 64bit Software Database, 64bit Driver Database, 64bit News (http://www.planetamd64.com)
- 64-bit Support, Forum, 64-bit News and Database (http://www.64bitsupport.com/)
- Extended64.com - 64bit forums, help, news and database of drivers/software (http://www.extended64.com)
Drivers
- ATi.com - ATI Display 64bit Driver (https://support.ati.com/ics/support/default.asp?deptID=894&task=knowledge&folderID=27&questionID=3373)
- Nvidia.com - Nvidia Display 64bit Driver (http://www.nvidia.com/object/winxp64_57.30)
- AMD64 Device Driver Support for Windows and Linux (http://www.amd.com/us-en/Processors/DevelopWithAMD/0,,30_2252_869_875%5e10454,00.html?redir=IEGFC07) - List of manufacturers and products that feature a driver for 64bit OSsfr:Windows XP 64