Program to find 1’s complement of an 8-bit number

Q. Write an 8085 program and draw a flowchart to find 1’s complement of an 8-bit number.(8085 Microprocessor Program)



Address Mnemonics Operand Opcode Comments
2000 LDA 3000H 3A Load H-L pair with data from 3000H.
2001     00  
2002     30  
2003 CMA   2F Complement accumulator.
2004 STA 3001H 32 Store the result at memory location 3001H.
2005     01  
2006     30  
2007 HLT   76 Halt


Before Execution:

3000H:    85H

After Execution:

3001H:     7AH

Program Explanation

  1. This program finds the 1’s complement of an 8-bit number stored in memory location 3000H.
  2. Let us assume that the operand stored at memory location 3000H is 85H.
  3. The operand is moved to accumulator from memory location 3000H.
  4. Then, its complement is found by using CMA instruction.
  5. The result is stored at memory location 3001H.

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