A method of operating a storage controller which is included in a data storage device and initializes at least one main memory of the data storage device includes: transmitting, by a processor of the storage controller, a first indication signal for indicating initialization of the main memory of the data storage device to a first memory initialization device; generating, by a register of the first memory initialization device, a selection signal corresponding to the first indication signal, and outputting, by a memory set of the first memory initialization device, a first initialization signal to the main memory in response to the selection signal to initialize the main memory.