Abstract: The disc file system being improved includes a motor driven transducer carriage for positioning the transducer in selected cylinder positions. A command unit issues step pulses and the carriage provides detent pulses respectively representing the number of tracks (cylinders) to be and being crossed when the carriage is caused to move and moves from one cylinder position to another one. These pulses are processed so that overlap is avoided in that following the trailing edge of each step or detent pulse, a process pulse, is produced either with or without delay depending on the need to avoid conflict. The process pulses to be produced are up an down counted for tracking actual carriage movement, and the total count is zero when the carriage has arrived at the desired position.