INT 67 - LIM EMS 4.0 - GET/SET HANDLE ATTRIBUTES
        AH = 52h
        AL = subfunction
            00h get handle attributes
                Return: AL = attribute
                            00h handle is volatile
                            01h handle is nonvolatile
            01h set handle attributes
                BL = new attribute (see returned AL)
            02h get attribute capability
                Return: AL = attribute capability
                            00h only volatile handles supported
                            01h both volatile and non-volatile supported
        DX = handle
Return: AH = status
            00h successful
            80h internal error
            81h hardware malfunction
            83h invalid handle
            84h undefined function requested
            8Fh undefined subfunction
            90h undefined attribute type
            91h feature not supported