INT 33 - PCMOUSE - SAVE MSMOUSE STATE
        AX = 0050h
        BX = buffer size (ignored by some driver versions)
        ES:DX -> buffer
Return: AX = FFFFh if successful
Notes:  the buffer must be large enough to hold the entire state, or following
          data will be overwritten by state data in versions which ignore BX;
          use INT 33/AX=0042h to get the required size
        this function is also supported by the Genius Mouse 9.06 driver
SeeAlso: AX=0052h