INT 67 - Microsoft EMM386.EXE v4.20+ - INSTALLATION CHECK
        AX = FFA5h
Return: AX = 845Ah if loaded
            BX:CX -> API entry point
Notes:  this call is available even if EMM386 is not providing EMS
        if no other program has hooked INT 67, an alternate installation
          check is to search for the string
          "MICROSOFT EXPANDED MEMORY MANAGER 386" early in the INT 67
          handler's segment, usually at offset 14h

Call API entry point with:
        AH = 00h get memory manager's status
            Return: AH = status
                        bit 0: not active (OFF)
                        bit 1: in "Auto" mode
        AH = 01h set memory manager's state
            AL = new state (00h ON, 01h OFF, 02h AUTO)
        AH = 02h Weitek coprocessor support
            AL = subfunction
                00h get Weitek support state
                    Return: AL = status
                                bit 0: Weitek coprocessor is present
                                bit 1: Weitek support is enabled
                01h turn on Weitek support
                02h turn off Weitek support
     --- v4.20-4.41 only ---
        AH = 03h Windows support???
            AL = subfunction (00h, 01h)
        AH = 04h print copyright notice to standard output
                 (using INT 21/AH=09h)
        AH = 05h print available report
                 (the one shown when running EMM386 from the DOS prompt)