Difficulty: Easy
Correct Answer: 16
Explanation:
Introduction / Context:
Many TTL/CMOS ALU devices expose several arithmetic and logic functions through function-select inputs. Recognizing the breadth of operations helps when choosing a part for educational or small-scale designs.
Given Data / Assumptions:
Concept / Approach:
ALUs commonly present 4 function-select lines, enabling up to 16 combinations (2^4) for arithmetic/logic operations such as addition, subtraction (via complement and add), increment, decrement, transfer, AND, OR, XOR, and compare variants. While specific truth tables vary by vendor, a 16-operation repertoire is characteristic for such ALU families.
Step-by-Step Solution:
Verification / Alternative check:
Comparing with canonical ALUs (e.g., educational 4-bit ALUs) shows comparable 16-operation maps.
Why Other Options Are Wrong:
Common Pitfalls:
Confusing the number of logic-only operations with total ALU functions; overlooking that select lines address both arithmetic and logic modes.
Final Answer:
16
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