A significant capability of the Intel 80386 and 80486 processor families is their ability to emulate the Intel 8086 processor. This emulated state is known as virtual 8086 (V86) mode. The Multiple Virtual DOS Machines component of OS/2 Version 2.0 makes use of this mode to provide emulation of a native DOS environment for applications executing in virtual DOS machines. The 8086 processor hardware emulation is provided by the 8086 Emulation component of MVDM. Other aspects of the DOS environment, such as program loading and execution and device driver support, are provided by the DOS Emulation component, which is described in MVDM DOS Emulation, and by virtual device drivers, described in Device Drivers.
This chapter provides an overview of V86 mode, and describes the operation of the 8086 Emulation component.