A memory module that includes a buffer and a plurality of synchronous memory devices. The memory module also includes bidirectional bus lines, and each of the synchronous memory devices has bidirectional data terminals. The buffer is configured to regenerate signals received on the bus lines for receipt by the synchronous memory devices, and to regenerate signals received from any one of the synchronous memory devices for receipt by the bus lines. The memory module may further include command lines and a clock line for providing commands and a clock signal to the synchronous memory devices via a command buffer. The combined data bus width of the memory module may be greater than the data bus width of any single one of synchronous memory device, and the total address space provided by the memory module may be larger than the data space for any single synchronous memory device.