A LAN interface apparatus determines which function of a plurality of functions of a multifunction peripheral apparatus is to be used. This determination may be performed by determining which function of the plurality of functions is selected in the multifunction peripheral apparatus. This selection may be performed as a result of a user specifying a desired function by pressing a relevant key provided on the multifunction peripheral apparatus. The multifunction peripheral apparatus then sends information to the LAN interface apparatus which thus determines the function being used in the multifunction peripheral apparatus. Then, the LAN interface apparatus appropriately alters a data storage area of a common memory and thus a resulting data storage area of the common memory is appropriate for a data flowing ratio between data flowing along two opposite directions, which ratio depends on the function being selected in the multifunction peripheral apparatus.