Radio Systems has introduced new features to its CT-6 clock line: down timing, infrared remote control and SMPTE. CT-6 clocks can run on their own internal crystal oscillator, accept a master-generated serial time signal or accept a top-of-hour closure. They can be configured in master/slave modes with a desktop or large display model serving as the crystal or GPS master. Up to 50 digital and five analog clocks may be driven by the master units.