Digital clock minutes section: input rate of the MOD-6 (tens-of-minutes) counter In a 12-hour digital clock minutes chain (units-of-minutes: MOD-10; tens-of-minutes: MOD-6), what is the correct input event rate for the tens-of-minutes (MOD-6) counter?

Introduction / Context:
Digital clocks represent minutes with two cascaded counters: a MOD-10 for units (0–9) and a MOD-6 for tens (0–5). Understanding the carry/rollover behavior between these counters is essential to design correct timing chains in HDL.

Given Data / Assumptions:

• Seconds counter provides a 1 pulse per minute output to the minutes-units counter (MOD-10).
• The minutes-units counter generates a carry when it rolls over from 9 to 0.
• The tens-of-minutes counter (MOD-6) should advance on that carry event.

Concept / Approach:
The tens-of-minutes counter must increment once for every ten minutes elapsed, because the units-of-minutes runs from 0 to 9 each minute. Thus, its input rate is one-tenth the minutes-units input rate.

Step-by-Step Solution:

Verification / Alternative check:
Timing diagram over one hour shows six increments of the tens-of-minutes counter at 00, 10, 20, 30, 40, and 50 minutes.

Why Other Options Are Wrong:

• A: Incorrect; that rate applies to the minutes-units counter, not tens.
• C: Physically impossible; tens counter does not increment multiple times per minute.
• D: It increments six times per hour, not once.

Common Pitfalls:
Feeding the tens counter directly with the 1-minute tick rather than the units’ carry line leads to an illegal 0–5 sequence every minute.

Final Answer:
1 pulse every 10 minutes