ISRO Electronics & Communication (ECE) 2013 - Question 17

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Topic: Microprocessors

For the 8085 assembly language program given below, the content of the accumulator after the execution of the program is
3000 MVI A, 45H
3002 MOV B, A
3003 STC
3004 CMC
3005 RAR
3006 XRA B

  • A. 00H
  • B. 45H
  • C. 67H
  • D. E7H

Answer: C. 67H

Explanation: MVI A, 45H loads A with 45H (0100 0101). MOV B, A copies it to B, so B is 45H. STC sets the carry flag (CY=1). CMC complements the carry flag (CY=0). RAR rotates the accumulator right through carry: A becomes 0010 0010 (22H) and CY becomes 1. XRA B performs XOR operation of B with accumulator: 22H XOR 45H = 0010 0010 XOR 0100 0101 = 0110 0111 = 67H.

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