Hexadecimal to Decimal conversion | 8085 Lab Program

 Section: Array Operations & Code Conversions

Aim: To convert a given hexadecimal number to decimal number and also to verify the result.

Apparatus Required: 8085 microprocessor kit, key board.

Algorithm:

1. Initialize the memory location to the data pointer.
2. Increment B register.
3. Increment accumulator by 1 and adjust it to decimal every time.
4. Compare the given hexadecimal number with B register value.
5. When both match, the equivalent decimal value is in A register.
6. Store the resultant in memory location.

Program:

Address	Label	Mnemonics	Operand	Comment
4100		LXI	H, 4200	Initialize HL reg. to 4200H
4103		MVI	A, 00	Initialize A register
4105		MVI	B, 00	Initialize B register
4107		MVI	C, 00	Initialize C register for carry
4109	LOOP	INR	B	Increment B reg
410A		ADI	01	Increment A reg
410C		DAA		Decimal Adjust Accumulator
410D		JNC	NEXT	If there is no carry go to NEXT
4110		INR	C	Increment C register
4111	NEXT	MOV	D, A	Transfer A to D
4112		MOV	A, B	Transfer B to A
4113		CMP	M	Compare M & A
4114		MOV	A, D	Transfer D to A
4115		JNZ	LOOP	If acc and given number are not equal, then go to LOOP
4118		STA	4201	Store the result in a memory location
411B		MOV	A, C	Transfer C to A
411C		STA	4202	Store the carry in another memory location
411F		HLT		Stop the program

Observation:

• Input:
  • Address 4200: D5
• Output:
  • Address 4201: 13
  • Address 4202: 02

Result: Thus an ALP program for conversion of hexadecimal to decimal was executed and the result is verified.

Flowchart:

               +-------------------+
               |       START       |
               +---------+---------+
                         |
                         v
               +-------------------+
               |   [HL] <- 4200H   |
               +---------+---------+
                         |
                         v
               +-------------------+
               |    [A] <- 00H     |
               +---------+---------+
                         |
                         v
               +-------------------+
               |    [B] <- 00H     |
               +---------+---------+
                         |
                         v
               +-------------------+
               |    [C] <- 00H     |
               +---------+---------+
                         |
                         v <------------------+
               +-------------------+          |
               |   [B] <- [B] + 1  |          |
               +---------+---------+          |
                         |                    |
                         v                    |
               +-------------------+          |
               |   [A] <- [A] + 1  |          |
               +---------+---------+          |
                         |                    |
                         v                    |
               +-------------------+          |
               |   Decimal Adjust  |          |
               |    Accumulator    |          |
               +---------+---------+          |
                         |                    |
                         v                    |
                       /   \                  |
                     /  Is   \                |
                   /  there a  \              |
                  <   Carry?   >              |
                   \  (CY = 1) /              |
                     \      /                 |
                       \  /                   |
                        |                     |
            +-----------+-----------+         |
            |                       |         |
           YES                      NO        |
            |                       |         |
            v                       |         |
  +-------------------+             |         |
  |   [C] <- [C] + 1  |             |         |
  +---------+---------+             |         |
            |                       |         |
            +-----------+-----------+         |
                        |                     |
                        v                     |
              +-------------------+           |
              |    [D] <- [A]     |           |
              |    [A] <- [B]     |           |
              +---------+---------+           |
                        |                     |
                        v                     |
                      /   \                   |
                    /  Is   \                 |
                  /   [A] =   \               |
                 <    [M]?     >              |
                  \           /               |
                    \       /                 |
                      \   /                   |
                       |                      |
           +-----------+------------+         |
           |                        |         |
          YES                       NO        |
           |                        +---------+
           v
 +-------------------+
 |    <- [A]         |
 |    [A] <- [C]     |
 |    <- [A]         |
 +---------+---------+
           |
           v
 +-------------------+
 |       STOP        |
 +-------------------+

Viva Questions:

1. What is meant by instruction DAA?
2. Why data bus is bi-directional?
3. Specifies the function of address bus and the direction of address bus?
4. How many memory location can be addressed by a microprocessor with the 14 address lines?
5. List various instructions that can be used to clear accumulator in 8085?
6. When the Ready signal of 8085 is sampled by the processor?
7. List out the similarities b/w the CALL_RET and PUSH_POP instructions?

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