OS/2 Version 2.0 enables the user to start multiple DOS applications in multiple concurrent VDMs, all of which are controlled by the Virtual DOS Machine Manager (VDMM).
Figure "MVDM Protected Mode processes"
The VDMM creates a VDM by:
Figure "VDM Exception Handling"
The VDMM is responsible for handling those 8086 instructions which cannot be executed in V86 mode, such as interrupts. Such instructions cause an exception to be generated by the 80386 processor; this exception is passed to an exception handler within the operating system, which checks the VM bit in the current process's EFLAGs control area. If the VM bit is set, control is passed to the VDMM. The VDMM therefore runs as a protected mode system level process at privilege level 0.