Apparatus and method for monitoring the presence of cables connected to ports of a computer network controller and automatically reconfiguring the network when cables are connected to or removed from the controller

An apparatus for monitoring whether a cable is coupled to a port of a computer network, said apparatus comprising:

• an oscillator generating an oscillator signal at a first frequency;
• a frequency indicator coupled to said oscillator for indicating the frequency of said oscillator signal;
• a comparator coupled to said frequency indicator for comparing the indicated frequency of said oscillator signal to a predetermined frequency, said comparator outputting a cable detect signal whose value is dependent on said comparison;
• a controller having an input coupled with said comparator to receive said cable detect signal, said controller, responsive to said cable detect signal, coupling said port to a path of said computer network.

An apparatus for reconfiguring a computer network responsive to whether a twisted-pair cable is coupled to a port of the network comprising:

• a) an oscillator generating an oscillator signal at a first frequency;
• b) a connector by which a twisted-pair cable may be attached;
• said connector having an A contact and a B contact;
• c) a differential line receiver having an A input and a B input and at least one output, the A input of the line receiver being coupled to the A contact of the computer and the B input of the line receiver being coupled to the B contact of the connector, the differential line receiver used to receive data from a computer system;
• d) a frequency measurement circuit monitoring the frequency of the oscillator signal, the frequency measurement circuit generating a cable detect signal whenever the oscillator is oscillating at the second frequency;
• e) a controller having an input coupled to the frequency measurement circuit to receive said cable detect signal, the controller, responsive to said cable detect signal, coupling the port of the computer network.

An apparatus for reconfiguring a computer network responsive to whether a twisted-pair cable is coupled to a port of the network comprising:

• a) an oscillator generating an oscillator signal at a first frequency;
• b) a connector by which a twisted-pair cable may be attached, said connector having an A contact and a B contact;
• c) a differential line drive having an A output and a B output and at least one output, the A output of the line drive being coupled to the A contact of the connector and the B input of the line drive being coupled to the B contact of the connector, the differential line driver used to send data to a computer system;
• d)frequency measurement circuit monitoring the frequency of the oscillator signal, the frequency measurement circuit generating a cable detect signal whenever the oscillator is oscillating at the second frequency;
• e) a controller having an input coupled to the frequency measurement means to receive said cable detect signal, the controller, responsive to said cable detect signal coupling the port of the computer network.