Native x86-64 Windows software

Native x86-64 Windows software is software compiled to run on x86-64 processors under the Microsoft Windows operating system.

Such software requires both a x86-64 processor and a x64 Windows operating system, and will not run under 32-bit Windows, on any x86-capable processor. Nor will this "64-bit software" run under the 64-bit Itanium (IA-64) processor.

Note that additionally, not all x64 software will run on all of the various x64 versions of Windows, there being incompatibilities between some designed for Windows Server 2003, XP x64 edition, Vista, and 7 — this applies especially to device drivers.

Comparison with 32-bit software

The benefits of running native x86-64 software instead of 32-bit software include improved performance, security and the ability to address and use more memory.^[1]

Generally, 32-bit software can run on x64 Windows, using the WoW64 ("Windows on Windows 64") subsystem included on all 64-bit versions of Windows. However, due to limitations in 64-bit Windows^[2], some 32-bit software components have incompatibility issues. These include:

• Kernel-mode device drivers
• Explorer shell extensions
• ActiveX controls
• Dynamic Link Libraries (DLLs)

32-bit software that runs on x64 Windows in the same manner as it does on 32-bit windows is usually called "x64-compatible" software (as opposed to "native x64" software).

See also

• Windows XP editions

References

1. ^ http://www.microsoft.com/servers/64bit/x64/benefits.mspx
2. ^ http://support.microsoft.com/kb/282423