1. A memory module comprising: first memory chips; second memory chips; a third memory chip; and a memory buffer to transfer first data with the first memory chips, to transfer second data with the second memory chips, and to transfer first error checking information corresponding to the first data with the third memory chip and to transfer second error checking information corresponding to the second data with the third memory chip, wherein the memory buffer determines an error address indicating a location in the third memory chip corresponding to one of the first error checking information or the second error checking information, the error address determined differently depending on whether the first data is being transferred with the first memory chips or the second data is being transferred with the second memory chips.