1. A method of controlling write operations in a phase change material (PCM) memory, the method comprising: for a first write operation targeting a part of the PCM memory, determining a number of bit differences between data requested to be stored by the first write operation and data in the part of the PCM memory; and controlling timing of performing a second write operation based on the determined number of bit differences between the data in the part of the PCM memory and the data requested to be stored by the first write operation.