1. A memory module, comprising: first connectors to connect the memory module to an external data bus and second connectors to connect the memory module to an external command and address bus; integrated circuit memory devices, each integrated circuit memory device to transfer a slice of data using one or more respective ones of the first connectors in connection with a memory access command common to multiple ones of the memory devices; data buffer devices, to buffer transfer of the slices of data, each buffer device to couple at least one of the integrated circuit memory devices with the external data bus; and at least one command-and-address buffer device to buffer provision of the memory access command to the multiple ones of the integrated circuit memory devices from the external command and address bus.