A general disadvantage of ring counters is that they are lower density codes than normal binary encodings of state numbers.
Instead of the reset line setting up the initial one-hot pattern, the straight ring is sometimes made self-initializing by the use of a distributed feedback gate across all of the outputs except that last, so that a 1 is presented at the input when there is no 1 in any stage but the last.
Note the small bubble indicating inversion of the Q signal from the last shift register before feeding back to the first D input, making this a Johnson counter.
[5] Early ring counters used only one active element (vacuum tube, valve, or transistor) per stage, relying on global feedback rather than local bistable flip-flops, to suppress states other than the one-hot states, for example in the 1941 patent filing of Robert E. Mumma of the National Cash Registor Company.
Straight ring counters generate fully decoded one-hot codes to that are often used to enable a specific action in each state of a cyclic control cycle.
[15][nb 1] Besides being an efficient alternative way to generate one-hot codes and frequency pre-scalers, a Johnson counter is also a simple way to encode a cycle of an even number of states that can be asynchronously sampled without glitching, since only one bit changes at a time, as in a Gray code.
Two such walking ring counters are perhaps the simplest way to generate the continuous-phase frequency-shift keying used in dual-tone multi-frequency signaling and early modem tones.