Multiple (e.g., four) memory devices on a module are connected to a common pair of differential data strobe signal conductors. The common pair of differential data strobe conductors are also coupled to a memory controller to time the transmission of data to the multiple memory devices and to time the reception of data from the memory devices. The controller calibrates two or more different data transmission delays relative to its transmission of a write data strobe signal on the common pair of differential data strobe conductors. The controller also calibrates to account for two or more different data reception delays (skew) relative to its reception of a read data strobe signal on the common pair of differential data strobe conductors.