In one aspect, a non-volatile memory system includes a plurality of memory cell arrays having different read stand-by times. For example, the non-volatile memory system may include a single-level cell (SLC) array composed of a plurality of SLCs, and a multi-level cell (MLC) array composed of a plurality of MLCs. In this case, the SLC array and the MLC array receive a read instruction at the same time and prepare to read data at the same time. However, the SLC array begins to read the data prior to the MLC array, and the MLC array begins to read the data once the SLC array has completely read the data.