A hard disk drive (HDD) is disclosed that includes a hard disk control (HDC) module and phase change memory (PCM). The PCM communicates with the HDC module and includes a plurality of memory cells that store data. Each of the memory cells includes a phase change material having N states. N is an integer greater than or equal to three. The HDC module caches at least one of user data and a computer program, which is stored by a magnetic storage medium that is associated with the HDD, in the PCM.