Understanding Counter Control Signals

This explanation details the necessary conditions for a digital counter to function correctly when counting upwards from an initial state of 0000.

Required Control Signal States for Upwards Counting

To achieve an upwards count starting from 0000, specific control signals must be active:

• Statement (c) CLEAR is high: The $CLEAR$ input typically resets the counter to its zero state (0000). Activating $CLEAR$ is the first step to ensure the count begins correctly.
• Statement (a) LOAD input is high: An active-high $LOAD$ input allows a specific value to be loaded into the counter. To start at 0000, this input ensures the initial value is set correctly, presumably loading 0000.
• Statement (d) Enable input is low: The $Enable$ input governs whether the counter progresses. An active-low $Enable$ signal, when low, permits the counter to increment upon receiving clock pulses, thus enabling the counting sequence.

Analysis of Statement (b)

Statement (b) $\overline{\text{LOAD}}$ input is high: This condition signifies that the $LOAD$ input is low. A low $LOAD$ input usually prevents loading data. As the correct configuration requires the $LOAD$ input to be high (statement a) to set the initial state, this condition (b) is incompatible and thus incorrect for this specific counting requirement.

Conclusion

Therefore, the combination of statements (a), (c), and (d) represents the required conditions for the counter to count upwards from 0000.