Virtual DOS Machine: The name of Microsoft’s technology allowing to run MS-DOS programs on Intel 80386 or higher computers when there is already another operating system running and controlling the hardware.

Consider the following scenario. You develop an application that uses the VDMEnumProcessWOW function to enumerate virtual DOS machines (VDMs) that are running 16-bit Windows tasks. However, when the application runs on a computer that is running a 32-bit version of Windows Vista, the application returns no output. Or, the application returns incorrect output.

For example, you may experience this problem when you use the application to return a list of 16-bit Notepad instances.