Memory system and memory module control method

A memory module control method comprising:

• writing four n-bit data received from an external system in a memory module comprising first to eighth semiconductor memories;
• and
• reading the four n-bit data from said memory module in response to on a request from said external system,
• wherein said writing comprises:
• receiving the four n-bit data from said external system;
• generating three n-bit error detection and correction code based on the four n-bit data;
• storing the four n-bit data in said first to fourth semiconductor memories, respectively;
• and
• storing the three n-bit error detection and correction code in said fifth to seventh semiconductor memories, respectively, and
• wherein said reading comprises:
• reading the four n-bit data from said first to fourth semiconductor memory in response to the request from said external system, respectively;
• reading the three n-bit error detection and correction code from said fifth to seventh semiconductor memories, respectively;
• executing error detection to every two of the four n-bit data read from said first to fourth semiconductor memories based on the three n-bit error detection and correction code read from said fifth to seventh semiconductor memories;
• and
• executing error correction to one n-bit data related to an error, of the four n-bit data based on the three n-bit error detection and correction code, when the error is detected in the four n-bit data.