OS/2 Version 2.0 MVDM 8086 Emulation provides "pure" 8086 emulation support for the V86 mode of the Intel 80386 SX and DX processors. [The Intel 80486 SX and DX processors also provide a compatible V86 mode, and are therefore supported by MVDM.] In a native 8086 processor environment, an application can access all available memory up to 1MB and can execute all 8086 processor instructions when running as a single task in an unprotected environment. However, virtual DOS machines run only in protected mode, and an application running in the V86 mode environment therefore has limited access to system memory and cannot execute all CPU instructions; only the OS/2 Version 2.0 operating system itself has full access to memory and the processor.
Each VDM runs as a single V86 mode process, emulating all DOS operating system functions and providing a compatible DOS environment unaffected by other VDMs in the system. In the VDM environment, therefore, an application behaves as if it has complete control over system processor and memory resources. In this way, full application function is provided while preserving the integrity of other applications and of the system as a whole.
The 8086 Emulation component provides the following:
8086 Emulation is described in more detail in 8086 Emulation.
Note that the 8086 Emulation component does not provide DOS or hardware-specific emulation. These emulations are provided by the DOS Emulation component (described in more detail below and in MVDM DOS Emulation) and virtual device drivers (described in more detail below and in Device Drivers) respectively.