The data processing method reversibly processing data information input to a data processing device by a processing unit including a data volume reducing unit reducing a data volume of the data information, and a developing unit reconstructing data information reduced in the data volume reducing unit. In one aspect, a selected oscillation is applied to the cutting element so that at least some of the stress energy stored in an earthen formation is maintained after fracture of the rock is initiated. The stator includes a core and a plurality of sets of conductive windings, each set including a predetermined number of individual conductive windings and associated with an electrical phase. When the final depth of the string bore is reached, the drilling tool is retracted into the starter drill pipe by axial movement of the clamping device and a free space is formed at the drift face of the string bore.