Method with which users enter instructions, in which said instructions are entered with sequences of voluntary movements of eye parts, the sequence required for entering a certain instruction being individual for each user. The radially outer surface of the land has its width increasing as it approaches the tool head. The thrust module includes a thrust bearing that absorbs thrust from the primary pump. Dynamic control circuitry may be used to control the settings of current sources, programmable resistors, and voltage source circuitry in the adjustable differential output driver automatically in real time.