INT 2fH 40xxH: Virtual Display Driver Functions

                                                     Compatibility: Win 3.0+ 

     See: 4000H (srvc: enable VM-assisted video save/restore)

          4001H (ntfy: about to switch to background)
          4002H (ntfy: about to switch to foreground)

          4003H (srvc: enter critical section)
          4004H (srvc: exit critical section)

          4005H (ntfy: saving video registers)
          4006H (ntfy: restoring video registers)

          4007H (srvc: disable VM-assisted save/restore)

   Notes: ■ These functions are used by programs which expect to be run in
            virtual machines under Enhanced-Mode Windows.

            They provide access to some Virtual Display Device (VDD)
            services and notifications to help them manage the screen as
            they are swapped into and out of the foreground.

            In general, these fns are used only by programs which do weird
            stuff to the video display; for instance, programs which
            display in video modes which are not supported by the VDD or
            perform on-the-fly modifications to on-screen fonts, etc.

          ■ The services are tools that can be called by VM-aware
            applications to access services provided by the VDD.

          ■ The notifications represent INT 2fH fns that are invoked by the
            Windows VDD.  To receive these notifications, VM-aware
            applications can intercept INT 2fH and watch for AX=40xxH.

See Also: INT 2fH: Multiplex Interrupt
          DOS Functions