Difficulty: Easy
Correct Answer: the Gate Enable is HIGH and the S and R inputs are both LOW
Explanation:
Introduction / Context: A gated S-R latch adds an enable (gate) control to the basic S-R latch so that input commands are effective only when the gate is asserted. Knowing the exact condition that causes a hold (no change) while enabled helps avoid accidental state changes and race-through issues in combinational-to-sequential interfaces.
Given Data / Assumptions:
Concept / Approach: The gated S-R truth table typically includes: E=1, S=0, R=0 → no change; E=1, S=1, R=0 → set; E=1, S=0, R=1 → reset; E=1, S=1, R=1 → invalid; and for E=0 the latch ignores S and R and simply holds. The question explicitly focuses on the hold condition when the device is enabled, so we select E=1 with S=0 and R=0.
Step-by-Step Solution:
Confirm active enable level: Gate Enable HIGH means inputs are “looked at.”Identify hold row in the truth table: S=0 and R=0 gives “no change.”Combine: E=1 and S=R=0 implies enabled but holding.Hence, the correct condition is “Gate Enable HIGH and S and R both LOW.”Verification / Alternative check:
Cross-check with a standard truth table from textbooks or datasheets; the mapping is consistent.Why Other Options Are Wrong:
the Gate Enable is HIGH: Incomplete—S and R values must be specified.the Gate Enable is LOW: This also produces hold, but the question asks for the enabled case.the S and R inputs are both LOW: Incomplete without the enable context.Common Pitfalls:
Forgetting that “enabled” narrows the condition subset.Confusing the enabled hold with the disabled ignore case.Final Answer:
the Gate Enable is HIGH and the S and R inputs are both LOW
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