A memory system includes an error checking and correction (ECC) engine configured to perform error checking and correction of data temporarily stored in a first memory array and data read out from the first memory array according to a first method, and perform error checking and correction of data stored in a second memory array after read out from the first memory array and data read out from the second memory array according to a second method, wherein the first method and the second method are selected in response to a control signal having at least a first logic level, and the second method checks and corrects data errors occurring at a higher rate compared the first method.