Abstract: Ports including at least input and output signal lines are collected into port groups. For each port group three separate clock synchronized time division switches are connected respectively to the input signal lines, bus highways and the output signal lines. All time division switches of the system are synchronized by a system clock and each one is controlled by its own storage of selected addresses in time slot order. A plurality of bus highways is provided and the input time division switch connects signals to a specific bus highway of the system. A second time division switch selects the bus highway for connection to the output section of the port group. A third time division switch selects the output port to which the selected bus highway is connected. In one embodiment the bus highways directly connect the port groups. In another, a central inter-connect matrix is provided to make the connection between the first and second time division switches.

Abstract: An ink level control for a printing press is disclosed having an ultrasonic ink level sensor to receive an echo signal representative of the level of the ink in the ink fountain. A control is provided whereby the ink level is maintained at a desired operating level and conditions of excessively low and high ink levels are also detected by the sensor. An echo loss detection network is provided to warn the operator and inhibit ink feeds. The control is designed to prevent overflow of the ink fountain.