Windows on Windows

This is an old revision of this page, as edited by Ghettoblaster (talk | contribs) at 13:14, 5 April 2008. The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.
This article is about the Win16 subsystem in 32-bit Windows NT. For the 32-bit compatibility layer in 64-bit Windows, see WOW64.

Windows on Windows, commonly referred to as WOW or WoW, is a critical component for backward compatibility of legacy code in Windows NT-based operating systems. WoW supports applications using the Win16 API and relies on NTVDM.

64-bit versions of Windows do not include the 16-bit WoW subsystem or NTVDM and therefore cannot run 16-bit Windows or DOS applications.

Win16 applications run as-is without preemptive multitasking or long filename support. These programs do not take advantage of the 32-bit version of Windows NT.