8 bit data division | 8085 Lab Program

 Section: Arithmetic & Logic Operations

Aim: To divide two 8-bit numbers stored in memory and also to verify the result.

Apparatus Required: 8085 microprocessor kit, key board.

Algorithm:

1. Load Divisor and Dividend.
2. Subtract divisor from dividend.
3. Count the number of times of subtraction, which equals the quotient.
4. Stop subtraction when the dividend is less than the divisor. The dividend now becomes the remainder. Otherwise, go to step 2.
5. Stop the program execution.

Program:

Address	Label	Mnemonics	Operand	Comment
4100		MVI	B,00	Clear B reg for quotient
4102		LXI	H,4200	Initialize HL reg. to 4200H
4105		MOV	A,M	Transfer dividend to acc.
4106		INX	H	Increment HL reg. to point next mem. Location.
4107	LOOP	SUB	M	Subtract divisor from dividend
4108		INR	B	Increment B reg
4109		JNC	LOOP	Jump to LOOP if result does not yield borrow
410C		ADD	M	Add divisor to acc.
410D		DCR	B	Decrement B reg
410E		INX	H	Increment HL reg. to point next mem. Location.
410F		MOV	M,A	Transfer the remainder from acc. to memory.
4110		INX	H	Increment HL reg. to point next mem. Location.
4111		MOV	M,B	Transfer the quotient from B reg. to memory.
4112		HLT		Stop the program

Observation:

• Input:
  • Address 4200: 06
  • Address 4201: 02
• Output:
  • Address 4202: 00 (Remainder)
  • Address 4203: 03 (Quotient)

Result: Thus an ALP was written for 8-bit division and also the result is verified.

Flowchart:

               +-------------------+
               |       START       |
               +---------+---------+
                         |
                         v
               +-------------------+
               |    [B] <- 00H     |
               +---------+---------+
                         |
                         v
               +-------------------+
               |   [HL] <- 4200H   |
               +---------+---------+
                         |
                         v
               +-------------------+
               |    [A] <- [M]     |
               +---------+---------+
                         |
                         v
               +-------------------+
               |  [HL] <- [HL] + 1 |
               +---------+---------+
                         |
                         v <------------------+
               +-------------------+          |
               |  [A] <- [A] - [M] |          |
               +---------+---------+          |
                         |                    |
                         v                    |
               +-------------------+          |
               |   [B] <- [B] + 1  |          |
               +---------+---------+          |
                         |                    |
                         v                    |
                       /   \                  |
                     /  Is   \                |
                   /  there a  \              |
                  <   Borrow?  >              |
                   \  (CY = 1) /              |
                     \      /                 |
                       \  /                   |
                        |                     |
            +-----------+-----------+         |
            |                       |         |
           YES                      NO        |
            |                       +---------+
            v
  +-------------------+
  |  [A] <- [A] + [M] |
  +---------+---------+
            |
            v
  +-------------------+
  |   [B] <- [B] - 1  |
  +---------+---------+
            |
            v
  +-------------------+
  |  [HL] <- [HL] + 1 |
  +---------+---------+
            |
            v
  +-------------------+
  |    [M] <- [A]     |
  |    (Remainder)    |
  +---------+---------+
            |
            v
  +-------------------+
  |  [HL] <- [HL] + 1 |
  +---------+---------+
            |
            v
  +-------------------+
  |    [M] <- [B]     |
  |     (Quotient)    |
  +---------+---------+
            |
            v
  +-------------------+
  |       STOP        |
  +-------------------+

Viva Questions:

1. What SUB M instruction will do?
2. Describe SBB M instruction.
3. Express the use of SUI with an example.
4. Where SBI can be used?
5. Give the purpose of the instruction LDAX D.
6. How will you perform Division using ADD instruction?
7. What is the need of ALE signal in 8085?
8. What are the addressing modes of 8085?
9. List the interrupt signals of 8085?

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