Sorting an array of data in Descending order | 8085 Lab Program

 Section: Array Operations & Code Conversions

Aim: To sort the given numbers in the descending order using 8085 microprocessor.

Apparatus Required: 8085 microprocessor kit, key board.

Algorithm:

1. Get the numbers to be sorted from the memory locations.
2. Compare the first two numbers and if the first number is smaller than second then interchange the number.
3. If the first number is larger, go to step 4.
4. Repeat steps 2 and 3 until the numbers are in required order.

Program:

Address	Label	Mnemonics	Operand	Comment
4100		MVI	B, 04	Initialize B reg with number of comparisons (n-1)
4102	LOOP3	LXI	H, 4200	Initialize HL reg. to 4200H
4105		MVI	C, 04	Initialize C reg with no. of comparisons (n-1)
4107	LOOP2	MOV	A, M	Transfer first data to acc.
4108		INX	H	Increment HL reg. to point next memory location
4109		CMP	M	Compare M & A
410A		JNC	LOOP1	If A is greater than M then go to loop1
410D		MOV	D, M	Transfer data from M to D reg
410E		MOV	M, A	Transfer data from acc to M
410F		DCX	H	Decrement HL pair
4110		MOV	M, D	Transfer data from D to M
4111		INX	H	Increment HL pair
4112	LOOP1	DCR	C	Decrement C reg
4113		JNZ	LOOP2	If C is not zero go to loop2
4116		DCR	B	Decrement B reg
4117		JNZ	LOOP3	If B is not Zero go to loop3
4118		HLT		Stop the program

Observation:

• Input:
  • Address 4200: 01
  • Address 4201: 06
  • Address 4202: 03
  • Address 4203: 07
  • Address 4204: 02
• Output:
  • Address 4200: 07
  • Address 4201: 06
  • Address 4202: 03
  • Address 4203: 02
  • Address 4204: 01

Result: Thus the descending order program is executed and the numbers are arranged in descending order.

Flowchart:

               +-------------------+
               |       START       |
               +---------+---------+
                         |
                         v
               +-------------------+
               |    [B] <- 04H     |
               +---------+---------+
                         |
                         v
               +-------------------+
               |   [HL] <- 4200H   |
               +---------+---------+
                         |
                         v
               +-------------------+
               |    [C] <- 04H     |
               +---------+---------+
                         |
                         v
               +-------------------+
               |    [A] <- [M]     |
               +---------+---------+
                         |
                         v
               +-------------------+
               |  [HL] <- [HL] + 1 |
               +---------+---------+
                         |
                         v
                       /   \
                     /  Is   \
                   / [A] >= [M]?\
                  <  (CY = 0)   >
                   \           /
                     \       /
                       \   /
                        |
            +-----------+------------+
            |                        |
           YES                       NO
            |                        |
            |                        v
            |              +-------------------+
            |              |    [D] <- [M]     |
            |              |    [M] <- [A]     |
            |              |  [HL] <- [HL] - 1 |
            |              |    [M] <- [D]     |
            |              |  [HL] <- [HL] + 1 |
            |              +---------+---------+
            |                        |
            +-----------+------------+
                        |
                        v
              +-------------------+
              |   [C] <- [C] - 1  |
              +---------+---------+
                        |
                        v
                      /   \
                    /  Is   \
                  /  [C] = 0? \
                 <            >
                  \ Is zero? / --- NO ---> (To LOOP2)
                    \      /
                      \  /
                       | YES
                       v
              +-------------------+
              |   [B] <- [B] - 1  |
              +---------+---------+
                        |
                        v
                      /   \
                    /  Is   \
                  /  [B] = 0? \
                 <            >
                  \ Is zero? / --- NO ---> (To LOOP3)
                    \      /
                      \  /
                       | YES
                       v
              +-------------------+
              |       STOP        |
              +-------------------+

Viva Questions:

1. Give out the purpose of the instruction DCX.
2. What is meant by CALL instruction?.
3. Briefly give out the LHLD instruction.
4. State the logic behind the Sorting an array of data in Descending order.
5. Name the various flag bits available in 8085 microprocessor?.
6. Give the significance of SIM and RIM instructions available in 8085?.
7. How do the address and data lines are demultiplexed in 8085?.

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