Program to Add two 8-bit numbers along with Carry

Q. Write an 8085 program and draw a flowchart to add two 8-bit numbers along with considering the carry.(8085 Microprocessor Program)



Address Mnemonics Operand Opcode Comments
2000 LXI H, 300H 21 Load H-L pair with address 3000H.
2001 00
2002 30
2003 MOV A, M 7E Move the 1st operand from memory to reg. A.
2004 INX H 23 Increment H-L pair.
2005 MOV B, M 46 Move the 2nd operand from memory to reg. B.
2006 MVI C, 00H 0E Initialize reg. C with 00H.
2007 00
2008 ADD B 80 Add B with A.
2009 JNC 200D D2 Jump to address 200DH if there is no carry.
200A     0D
200B     20
200C INR C 0C Increment reg. C.
200D INX H 23 Increment H-L pair.
200E MOV M, A 77 Move the result from reg. A to memory.
200F INX H 23 Increment H-L pair.
2010 MOV M, C 71 Move carry from reg. C to memory.
2011 HLT   76 HALT


Before Execution:

3000H:    FAH

3001H:     28H

After Execution:

3002H:     22H

3003H:     01H

Program Explanation

  1. This program adds two operands stored in memory location 3000H and 3001H, along with considering the carry produced (if any).
  2. Let us assume that the operands stored at memory location 3000H is FAH and 3001H is 28H.
  3. Initially, H-L pair is loaded with the address of first memory location.
  4. The first operand is moved to accumulator from memory location 3000H and H-L pair is incremented to point to next memory location.
  5. The second operand is moved to register B from memory location 3001H.
  6. Register C is initialized to 00H. It stores the carry (if any).
  7. The two operands stored in register A and B are added and the result is stored in the accumulator.
  8. Then, carry flag is checked for carry. If there is a carry, C register is incremented.
  9. H-L pair is incremented and the result is moved from the accumulator to memory 3002H.
  10. H-L pair is again incremented and carry (either 0 or 1) is moved from register C to memory location 3003H.

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