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winevdm on 64-bit Windows


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Download latest version (unstable, slower than stable version)

16-bit Windows (Windows 1.x, 2.x, 3.0, 3.1, etc.) on 64-bit Windows

An altered version of winevdm (a 16-bit Windows emulator), ported to 64-bit Windows.

How to compile

  • Install Visual Studio 2017
  • Install binutils
  • Edit PropertySheet.props
  • Compile

How to run

  • Drag and drop Win16 executable file to otvdm.exe or execute otvdmw.exe.

How to install

  • Download or compile
  • Edit install.reg
  • Register install.reg
  • You can execute Win16 binaries directly!

If you install v0.4.x, you should add these to install.reg and register install.reg again.

[HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Microsoft\Windows NT\CurrentVersion\NtVdm64\OTVDM]
"CommandLine"="\"%m\" %c"

How does it work?

This program contains the following items

  • CPU Emulator
    • 64-bit Windows cannot modify LDT(NtSetInformationProcess(,ProcessLdtInformation,,) always returns error)
  • wine based Win16->Win32 conversion codes:
BOOL16 WINAPI DestroyWindow16( HWND16 hwnd )
    return DestroyWindow( WIN_Handle32(hwnd) );

Relay routines from 16-bit to 32-bit are autogenerated by convspec

53  pascal -ret16 DestroyWindow(word) DestroyWindow16
  • DOS emulation for Win16
  • 16-bit <=> native HANDLE conversion
  • Fix compatibility problems, fix compatibility problems


When 64-bit Windows detects a 16-bit installer, it has a mechanism to start an alternative installer which is not 16-bit. This program uses it.

WINDOWS directory redirection

Some Win16 programs try to save their settings in %WINDIR%<filename>.ini

In recent Windows, it is not allowed to save to %WINDIR%, so it redirects.


winevdm.exe [--app-name app.exe] command line
winevdm.exe CALC.EXE

It can also run DOS executables (DOS emulator-like). You can set the DOS version with the VDMDOSVER environment variable.