Memory module and test method thereof

The invention discloses a test method of the memory module and the module. To this module converts the differential serial data of n bits supplied from the outside when the plurality of semiconductor memory devices, and the normal operation of light and lead to a single parallel data of each of m bits into a single parallel data by a plurality of m-bit output in each of a plurality of semiconductor memory device, and converts the single parallel data by a plurality of m bits outputted from each of the plurality of semiconductor memory devices in a differential serial data of n bits outputted to the outside, the outside at the time of a test operation It is comprised of a buffer which buffers a single parallel data of 2n bits to be applied to the output of a plurality of semiconductor memory devices, and outputs to buffer a single parallel data of a plurality of m bits output from the plurality of semiconductor memory devices to the external It is. Thus, it can be tested using conventional testers and there is no need to configure the test pattern data for testing of the semiconductor memory device of the memory module separately.