Abstract: The present invention relates to a data communication system with a data processing device comprising a network interface for the transmission of data from and to a network. To achieve a universal network compatibility for the data processing device, independent of the structures thereof and, furthermore, a rapid economical networking, the network-interface is formed by a mass storage interface for the data processing device and a data conversion device connected therewith, which converts mass storage data into network data and vice versa. The conversion of network data into mass storage data and vice versa, permits data delivered by means of the network to be treated by the data processing device as if stored on a local hard disk in the data processing device.