A data communication apparatus using a radio frequency and a data processing method thereof are provided. A wide-range of devices including a retractable magnet assembly, a disengagementengagement tool, a click on-click off device are described herein that may incorporate or interact with one or more of the multilevel correlated magnetic systems. Then, without erasing a second cell portion that includes the first portion, if respective levels of the cells of the second portion, that represent a second plurality of transformed bits obtained by a second transformation of the second input bits, according to the mapping, are accessible from the current cell levels, the second portion is so programmed to store the second transformed bits.