Memory systems are provided. A memory system may include a plurality of nonvolatile memories and a memory controller configured to control the plurality of nonvolatile memories. Moreover, the memory system may include an input/output buffer circuit connected between the memory controller and the plurality of nonvolatile memories. A data channel may be connected between the memory controller and the input/output buffer circuit, and first and second internal data channels may be connected between the input/output buffer circuit and respective first and second groups of the plurality of nonvolatile memories. The input/output buffer circuit may be configured to connect the data channel to one of the first and second internal data channels.