Abstract: A gateway device is disclosed which processes only really necessary information for gatewaying and thereby prevents unnecessary increases in communication traffic on a communication bus to which data is sent through the gatewaying. When it is judged that the contents of received data concern a command that does not need gatewaying, the processing for gatewaying is inhibited. When it is judged that the contents of the received data show information that should be processed for gatewaying only when there is a change in the contents, the contents are compared with the latest contents of the same kind of information stored in a memory, to determine whether there is a change in the contents, and the processing for gatewaying is inhibited when it is determined that there is no change.

Abstract: The present invention provides a security system for audio equipment which allows users to easily release a security operation without having to remember any identification numbers or codes. The present invention provides a security system for audio equipment in which audio equipment in an inoperable condition is changed into an operable condition when data recorded on a recording medium during a playback condition matches identification data stored in a memory. Thus, the present invention allows users to easily release the security operation without compromising the level of security. Furthermore, the present invention prevents the audio equipment from being placed in an unlockable condition due to careless operation of users.