Preset pattern for a ring counter What preset condition is required for a ring shift counter before clocking begins?

Introduction / Context:
A ring counter is a shift register with its serial output fed back to the serial input. It cycles a single active bit through its stages, generating one-hot codes widely used in sequencing and timing applications.

Given Data / Assumptions:

• Ring counter built from n flip-flops.
• Feedback is direct (not inverted), so the active state is 1.
• We want proper operation immediately after preset.

Concept / Approach:

For a direct ring counter, the valid circulating pattern is one-hot: exactly one stage = 1 and all others = 0. Each clock shifts the 1 into the next flip-flop. Presetting all 1s or all 0s would stall the counter; a single 0 with the rest 1 would circulate zeros, not the intended one-hot 1.

Step-by-Step Solution:

Verification / Alternative check:

Waveforms of ring counters show the single 1 stepping through outputs; alternative preset patterns fail to produce the canonical sequence.

Why Other Options Are Wrong:

• All 1s or all 0s: no single active bit to circulate.
• Single 0, rest 1: describes an inverted (0-hot) behavior, not the standard ring counter.

Common Pitfalls:

• Confusing ring counters with Johnson counters, which use inverted feedback and produce 2n states.

Final Answer:

a single 1, the rest 0