The information in this article applies to:
- Microsoft Windows NT operating system, version 3.1
- Microsoft Windows NT Advanced Server, version 3.1
SUMMARY
This article covers the registry entries for Windows NT virtual DOS
machines (VDMs).
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet
\Control\VirtualDeviceDrivers
This registry entry contains all the virtual device drivers (VDDs)
that are loaded in the VDM at initialization. This is entry is mainly
intended for independent hardware vendors (IHVs) who want to provide
virtual device drivers with their native device drivers. By default,
this entry does not have any VDDs.
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\WOW
This registry entry supports the following keys:
- cmdline: The command line which NT uses to create NT virtual
DOS machines (VDMs) for MS-DOS-based applications.
This entry is not useful for end users in any way.
- size: This tells NT what should be total memory size for
the VDM created for MS-DOS-based applications. This
includes conventional and extended memory. Default
value is 0, which means NT should choose the size
depending on the machine configuration. If this value
is altered, NT uses it rather than determining a value
itself.
- wowcmdline: Same as cmdline described above but used by Windows on
Windows (WOW) VMDs.
- wowsize: same as size described above but used by WOW VDMs.
- KnownDLLs: This is only for WOW applications. If a DLL name is
included in this entry and the application loads it
without specifying the full path, the WOW subsystem
loads that DLL from the Windows NT system directory
(\SYSTEM32). This ensures the Windows NT loads a
specific version of the WOW DLL rather than the
application's version of that DLL (since the
application's version of the DLL may not work under
Windows NT.
- LPT_Timeout: This is used by MS-DOS-based applications. There is no
specific call to tell MS-DOS that the print job has
completed. Under Windows NT (which spools print jobs),
it is important to close the print job for printing to
start. NT VDMs uses this timeout value to detect no
printing activity before closing the print job handle.
The default value is 15 seconds.