ABSTRACT
This chapter covers the reading and writing of magnetic recording media as applied to magnetic tapes, disks, and other magnetic systems. It presents various coding techniques that are used in writing binary data on a magnetic surface. The coding techniques include: return to zero (RZ); nonreturn to zero (NRZ); nonreturn to zero inverted (NRZI); frequency modulation (FM); phase encoding (PE); modified FM (MFM); run-length limited (RLL); group-coded recording; peak shift; write precompensation; and vertical recording. A major consideration when choosing a particular coding technique is the ability for the code to be self-clocking. The RLL code limits the number of contiguous 0s in a sequence and extends the concept in which certain clock transitions were removed. The MFM code was obtained from the FM code by removing certain clock transitions and retaining the remaining clock transitions.
