Device recognition (TTL/CMOS): “74HC283” corresponds to which function in standard logic families?
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A4-bit binary adder with carry in/out
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B4-to-16 decoder/demultiplexer
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CQuad 2-input NAND gate
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DDual D-type flip-flop with preset/clear
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E8-bit magnitude comparator
Answer
Correct Answer: 4-bit binary adder with carry in/out
Explanation
Introduction / Context:Recognizing common 74xx/HC device numbers is useful in digital design. The 74HC283 (and 74LS283) are classic 4-bit binary adders providing both Cin and Cout pins for cascading.
Given Data / Assumptions:
- Device code: 74HC283.
- Family: HC (High-speed CMOS), functionally similar to LS283 in TTL.
Concept / Approach:The 74HC283 implements a 4-bit parallel adder. It adds two 4-bit operands plus a carry in to produce a 4-bit sum and a carry out, enabling simple ripple or look-ahead architectures for wider adders.
Step-by-Step Solution:
Match IC number to function from standard catalogs.Confirm presence of Cin and Cout pins for cascading.Identify it as a 4-bit full adder device.Verification / Alternative check:Datasheets list pinouts for A3..A0, B3..B0, S3..S0, Cin, and Cout, confirming adder functionality.
Why Other Options Are Wrong:
Decoder/demux, NAND, flip-flop, comparator: Different 74xx numbers correspond to those functions, not 74HC283.Common Pitfalls:Confusing 74HC283 (adder) with 74HC138 (3-to-8 decoder) or 74HC00 (quad NAND).
Final Answer:4-bit binary adder with carry in/out