A system, includes a controller including a plurality of first external terminals configured to supply a command, a clock signal and an address, and communicate a data, and communicate a strobe signal related to the data, and a semiconductor memory device including a plurality of second external terminals corresponding to the plurality of first external terminals, one of the plurality of first external terminals and one of the plurality of second external terminals transferring an information specifying a length of a preamble of the strobe signal before the semiconductor memory device communicates the data.