the basic quickring system consisted of a number of single-direction 1-bit serial links carrying data, and one extra line carrying a 50 mhz clock signal. apple's implementation consisted of six data lines and the clock line using twisted-pair copper wiring (using lvds) embedded in a thin plastic strip. national semiconductor offered a variety of different implementations with up to 32 data lines, as well as the same signals multiplexted using frequency-division multiplexing in a single fibre optic cable for longer links between machines.