Abstract: A method of authorising use of a computer program only able to be used when an authorised message is received from an authorising system includes providing an authorisation system, making a request to use a computer program, signalling the request to the authorisation system, the authorisation system recording the use of the computer program and providing the authorisation message to the computer program upon receipt of the authorisation message the computer program may be used.

Abstract: A method of authorizing use of a computer program only able to be used when an authorized message is received from an authorizing system. The method includes providing an authorization system, making a request to use a computer program, signalling the request to the authorization system, the authorization system recording the use of the computer program and providing the authorization message to the computer program upon receipt of the authorization message the computer program may be used.

Abstract: A method of authorising use of a computer program only able to be used when an authorised message is received from an authorising system. The method includes providing an authorisation system, making a request to use a computer program, signalling the request to the authorisation system, the authorisation system recording the use of the computer program and providing the authorisation message to the computer program upon receipt of the authorisation message the computer program may be used.

Abstract: A communication system in which a controller is coupled over a communication path with two or more transponders, at least two of which transponders have different addresses, which controller and transponders communicate by periodically transmitting a broadcast message simultaneously to all transponders, transmitting an acknowledge message indicative of a new input received by at least one of the transponders, and individually polling all of the transponders using a polling technique which incorporates time periods to allow communication between the controller and a selected transponder, wherein the polling is only activated subsequent to the transmission of the acknowledge message. Periodic polls of all transponders in sequence provide supervision of the integrity of the system.