Device capability: The 74HC382 ALU provides how many distinct operations selectable via its function control inputs?

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:

  • Part family: 74HCxxx ALU device labeled 74HC382.
  • Function selects typically use multiple control lines.
  • Distinct operation count corresponds to combinations of select inputs.


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:

Identify typical select bus width (4 control bits).Compute possible operations: 2^4 = 16.Map common functions across arithmetic and logic groups.Conclude that 16 operations are provided.


Verification / Alternative check:
Comparing with canonical ALUs (e.g., educational 4-bit ALUs) shows comparable 16-operation maps.


Why Other Options Are Wrong:

  • 2 or 4: Far too few for a stand-alone ALU device.
  • 8: Insufficient for typical 4-select-line interfaces covering arithmetic and logic sets.


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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