In an information processing system, a plurality of information processing devices CHIP0 and CHIP1 are connected to multiport memory MPMEM0 that has a plurality of ports, and memory areas in multiport memory MPMEM0 can be altered to memory areas occupied by particular ports and memory areas shared by a plurality of ports. At such times, immediately after the occurrence of a request from a port, the status of this request may be supplied from other ports.