Programs of microprocessor

Microprocessor cannot understand a program written in Assembly Language .
Instruction are divided into bit pattern of word in byte as op-code(operation code) and operation
Instruction format has three types
1.One byte-has op-code
2.Two byte- has op-code and address
3.Three byte -has code and address lower byte and address higher byte

opcode

1 byte

opcode

Data / address

2 byte

opcode

Data / address Lower byte

Data Address Higher byte

3 byte

Instructions set for 8085 are classified into five categories:
1.Data transfer group instructions
2.Arithmetic group of instrructions
3.Logical group
4.Branching group
5.Machine Level
A program known in Assembler is used to covert a Assembly language program to machine language.
I) Data transfer copy operation:-

1)Load a 8 bit number in a register
2)Copy from Register to Register
3)Copy between Register and Memory
4)Copy between Input/Output Port and Accumulator
5)Load a 16 bit number in a Register pair
6) Copy between Register pair and Stack memory

Example :-
1.Load a 8 bit number 4F in register B                     -MVI   B ,4FH
2.Copy from Register B to Register A                     -MOV  A,B
3.Load a 16 bit number 2050 in Register pair HL     -LXI     H,2050H
4.Copy from Register B to Memory Address 2050  - MOV   M,B
5.Copy between Input/Output Port and Accumulator- OUT   01H      IN   07H

2)Arithmetic operations and instructions

1.Add 8 bit number 32 H to Accumulator                   -ADI   32 H
2.Add contents of Register B to Accumulator            - ADD B
3.Subtract a 8 bit number 32 H from Accumulator      - SUI   32H
4.Subtract contents of Register C from Accumulator   -SUB  C
5.Increment the contents of Register D by 1                - INR   D
6.Decrement the contents of Register E by 1               -  DCR   E

3)Logical and Bit Manipulation operations and instructions

1.Logically AND Register H with Accumulator             -ANA  H
2.Logically OR Register L with Accumulator                 -ORA   L
3.Logically XOR Register B with Accumulator             - XRA   B
4.Compare contents of Register C with Accumulator  -CMP  C
5.Complement Accumulator                                            -CMA
6.Rotate Accumulator Left                                             -RAL

Program to add two 8 bit numbers and store result in register C

1.Get two numbers
a) Load first no. in register D                                        MVI   D , 2H
b)Load  second no. in register E                                    MVI   E , 3H

2.Add them
a) Copy register D to A                                                  MOV  A , D
b) Add register E to A                                                     ADD E

3. Store result
a)Copy A to register  C                                                  MOV  C , A

4.Stop
a)Stop processing                                                            HLT


Program to add 8 bit number result can be more than 8 bits i.e.with carry present

1.Get two numbers
a) Load first no. in register D                                        MVI   D , 2H
b)Load  second no. in register E                                    MVI   E , 3H

2.Add them
a) Copy register D to A                                                  MOV  A , D
b) Add register E to A                                                     ADD E

3. Store result
a)Copy A to register  C                                                  MOV  C , A

4.Carry
a)Use conditional Jump instructions                           JNC  END

5.Change
a)Clear register B                                                          MVI  B ,0H
b)Increment B                                                                INR  B

6.Stop
a)Stop processing                                                         HLT