Hub, memory module, memory system and methods for reading and writing to the same

A hub, a memory module, a memory system, and methods for reading and writing to the same. In a test mode, memory module, memory device or memory unit identifying information may be ignored, so that all memory modules, memory devices or memory units may be test written or test read. Ignoring the memory identifying information may permit all the memory modules, memory devices or memory units to be written or read simultaneously, thereby decreasing test time.