Windows on Windows

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 (NT Virtual DOS Machine).

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.

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.

External links and references

* [http://www.microsoft.com/technet/archive/winntas/training/ntarchitectoview/ntarc_5.mspx?mfr=true Windows NT subsystems]
* [http://kb.iu.edu/data/acxn.html What are NTVDM and WOW?]
* [http://www.microsoft.com/technet/prodtechnol/windows2000serv/reskit/prork/preb_mon_ewvl.mspx?mfr=true Monitoring 16-bit Windows applications]