Priority encoder truth — 74148 I1 active case: For the 74148 8-to-3 priority encoder (active-low inputs and active-low outputs), when data input I1 is the only active input (asserted), what is the output code? The statement claims A0 = 0, A1 = 0, A2 = 1; evaluate its correctness.

Introduction / Context:
The 74148 is a classic MSI priority encoder with active-low inputs (I7 highest priority … I0 lowest) and active-low outputs (A2, A1, A0). Understanding its active-level conventions avoids frequent mistakes when interpreting output codes. This item checks your ability to translate between true binary values and active-low outputs for a specific asserted input.

Given Data / Assumptions:

• Device: 74148, 8-to-3 priority encoder.
• Inputs I0–I7 are active-low; lower numerical index implies lower priority.
• Outputs A2, A1, A0 are active-low representations of the binary index of the highest-priority active input.
• Only I1 is asserted (I1 = 0, others = 1), and enable is appropriately asserted.

Concept / Approach:
First, determine the true binary code for input 1: that is 001 (A2_true=0, A1_true=0, A0_true=1). Because the 74148 outputs are active-low, the pins A2, A1, A0 present inverted logic: A2 = NOT(A2_true), A1 = NOT(A1_true), A0 = NOT(A0_true). Thus, the pins read A2=1, A1=1, A0=0 for input 1 active (and no higher-priority input asserted).

Step-by-Step Solution:
Find true code: index 1 → 001.Apply inversion: A2 = 1, A1 = 1, A0 = 0.Check priority: no I2–I7 asserted, so index 1 is valid.Compare with claim: claimed A2=1, A1=0, A0=0 is different → statement is false.

Verification / Alternative check:
Consult a 74148 truth table: with I1 low, outputs are A2=A1=1, A0=0, and GS/EI pins reflect valid encoding/enable conditions.

Why Other Options Are Wrong:
“Correct” lists A2=1, A1=0, A0=0, which corresponds to true code 010 (index 2), not input 1. Enable polarity alone does not change the encoded pattern. Non-priority encoders differ in conflict handling but do not flip the active-low output convention of the 74148.

Common Pitfalls:
Forgetting outputs are active-low; neglecting priority (I7 dominates); misreading the bit order A2..A0 vs A0..A2.

Final Answer:
Incorrect (actual outputs are A2 = 1, A1 = 1, A0 = 0)