In one embodiment, a magnetoresistance random access memory (MRAM) such as a spin transfer torque (STT) random access memory (RAM), for example, has a subarray of bitcells and an electro-magnet positioned adjacent the subarray. A magnetic field is directed through a ferromagnetic device of bitcells of the first subarray to assist in the changing of states of bitcells of the subarray from a first state to a second state in which the ferromagnetic device of the bitcell is changed from one of parallel and anti-parallel polarization to the other of parallel and anti-parallel polarization. Accordingly, the content of the subarray may be readily preset or erased to one of the parallel or anti-parallel state with assistance from an electro-magnet.During a normal write operation, the bits to the other state are written. Other aspects are described herein.