CATV system

摘要

An image-data-system host computer outputs image data, the protocol of which is not disclosed. The image data outputted from the image-data-system host computer is transmitted via an image-data-system terminal and a video control unit to a data management unit. On the other hand, the data management unit decrypts in accordance with a protocol and acquires text data outputted from a text-system host computer whose protocol is disclosed. A signal transmitting unit transmits the image data and the text data outputted from the data management unit via a coaxial cable to a display unit. The display unit displays images in response to the image data and the text data received from the signal transmitting unit.