8 bit data multiplication | 8085 Lab Program

 Section: Arithmetic & Logic Operations

Aim: To multiply two 8 bit numbers stored at consecutive memory locations and also to verify the result.

Apparatus Required: 8085 microprocessor kit, key board.

Algorithm:

1. Initialize memory pointer to data location.
2. Move multiplicand to a register.
3. Move the multiplier to another register.
4. Clear the accumulator.
5. Add multiplicand to accumulator.
6. Decrement multiplier.
7. Repeat step 5 till multiplier comes to zero.
8. The result, which is in the accumulator, is stored in a memory location.

Program:

Address	Label	Mnemonics	Operand	Comment
4100	START	LXI	H, 4200	Initialize HL reg. to 4500
4103		MOV	B, M	Transfer first data to reg. B
4104		INX	H	Increment HL reg. to point next mem. Location.
4105		MVI	A, 00H	Clear the acc.
4107		MVI	C, 00H	Clear C reg for carry
4109	L1	ADD	M	Add multiplicand multiplier times.
410A		JNC	NEXT	Jump to NEXT if there is no carry
410D		INR	C	Increment C reg
410E	NEXT	DCR	B	Decrement B reg
410F		JNZ	L1	Jump to L1 if B is not zero.
4112		INX	H	Increment HL reg. to point next mem. Location.
4113		MOV	M, A	Transfer the result from acc. to memory.
4114		INX	H	Increment HL reg. to point next mem. Location.
4115		MOV	M, C	Transfer the result from C reg. to memory.
4116		HLT		Stop the program

Observation:

• Input:
  • Address 4200: 02
  • Address 4201: 04
• Output:
  • Address 4202: 08
  • Address 4203: 00

Result: Thus the 8-bit multiplication was done in 8085 μp using repeated addition method and also the result is verified.

Flowchart:

               +-------------------+
               |       START       |
               +---------+---------+
                         |
                         v
               +-------------------+
               |   [HL] <- 4200H   |
               +---------+---------+
                         |
                         v
               +-------------------+
               |    [B] <- [M]     |
               +---------+---------+
                         |
                         v
               +-------------------+
               |  [HL] <- [HL] + 1 |
               +---------+---------+
                         |
                         v
               +-------------------+
               |    [A] <- 00H     |
               |    [C] <- 00H     |
               +---------+---------+
                         |
                         v <------------------+
               +-------------------+          |
               |  [A] <- [A] + [M] |          |
               +---------+---------+          |
                         |                    |
                         v                    |
                       /   \                  |
                     /  Is   \                |
                   /  there a  \              |
                  <   Carry?   >              |
                   \          /               |
                     \      /                 |
                       \  /                   |
                        |                     |
            +-----------+-----------+         |
            |                       |         |
           YES                      NO        |
            |                       |         |
            v                       |         |
  +-------------------+             |         |
  |   [C] <- [C] + 1  |             |         |
  +---------+---------+             |         |
            |                       |         |
            +-----------+-----------+         |
                        |                     |
                        v                     |
              +-------------------+           |
              |   [B] <- [B] - 1  |           |
              +---------+---------+           |
                        |                     |
                        v                     |
                      /   \                   |
                    /  Is   \                 |
                  /   [B] = 0? \              |
                 <             >              |
                  \  Is zero? / -- NO --------+
                    \      /
                      \  /
                        | YES
                        v
              +-------------------+
              |  [HL] <- [HL] + 1 |
              +---------+---------+
                        |
                        v
              +-------------------+
              |    [M] <- [A]     |
              +---------+---------+
                        |
                        v
              +-------------------+
              |  [HL] <- [HL] + 1 |
              +---------+---------+
                        |
                        v
              +-------------------+
              |    [M] <- [C]     |
              +---------+---------+
                        |
                        v
              +-------------------+
              |       STOP        |
              +-------------------+

Viva Questions:

1. Define two’s complement of an 8-bit numbers.
2. What is meant by instruction ADC M?
3. What is the use of the instruction MOV A,M?
4. What is the function of program counter?
5. Mention the types of 8085 instruction set.
6. How will you perform multiplication using ADD instruction?
7. Describe about DAD B instruction.
8. What is the purpose of the instruction MOV M,A?

For all 2026 published articles list: click here: 

…till the next post, bye-bye & take care