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DAA instruction is used to perform which type of addition?

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Answer & Explanation

Correct AnswerA. BCD addition

Quick Explanation

DAA (Decimal Adjust Accumulator) is used after adding packed BCD numbers so the binary result in the accumulator is corrected to a valid BCD representation. Hence it is associated with BCD addition.

Formula / Key Relation

Typical adjustment:

If low nibble >9 or AC=1 → add 06H

If high nibble >9 or CY=1 → add 60H

Detailed Explanation

Concept & Reasoning

The processor performs ordinary binary addition first. DAA then examines the lower nibble/auxiliary carry and upper nibble/carry and conditionally adds 06H and/or 60H. This produces a valid two-digit packed BCD result.

How to Solve It in the Exam

DAA = Decimal Adjust after Addition.

Important Exam Point

DAA does not itself perform decimal addition; it corrects the accumulator after binary addition.

Related Revision Path

This question sits in the revision path Microprocessors and Interfacing → 8085 Microprocessor → Instructions .

Quick Trick

DAA = Decimal Adjust after Addition.

Common Mistake

Selecting binary addition because the ALU initially adds in binary.

Exam Tip

DAA does not itself perform decimal addition; it corrects the accumulator after binary addition.

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Exam Path

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