INT 2F - MS WINDOWS - WINDOWS ENHANCED MODE INSTALLATION CHECK
        AX = 1600h
Return: AL = 00h if Windows 3.x enhanced mode or Windows/386 2.x not running
        AL = 80h if Windows 3.x enhanced mode or Windows/386 2.x not running
        AL = 01h if Windows/386 2.x running
        AL = FFh if Windows/386 2.x running
        AL = anything else
            AL = Windows major version number >= 3
            AH = Windows minor version number
Note:   INT 2F/AH=16h comprises an API for non-Windows programs (DOS device
          drivers, TSRs, and applications) to cooperate with multitasking
          Windows/386 2.x and Windows 3.x and higher enhanced mode.
        certain calls are also supported in the Microsoft 80286 DOS extender in
          Windows standard mode