PURPOSE: To execute high-speed transmission irrespective of the distance of data transmission by providing a means which writes information in a first memory and communicates the information to the second memories of plural computers practically simultaneously through a data communication network.

CONSTITUTION: This system 10 is constituted of a memory 14, a system bus interface 12, a data transmitting means 16, a data receiving means 18, a transmission line 20 and reception line 22, and it executes communication between a host data processor 100 and a data network switch 400. The switch 400 repeats one write command to be sent to all other connected parts from the data transitting means 16. For this purpose, all the devices connected to the switch 400 access the memory 14 in which one storage forgetting is caused sometimes. The host data processor 100 can communicate with the memory 14 of this system 10. Thus, plural devices with each memory can share one memory 14, and high-speed long-distance data communication transmission link is realized.