8085 Data Transfer Instructions

       Here we are going to discuss about data transfer instructions which move data between register or memory locations.

As formerly seen in my previous posts in this Series, we divided the Series into four parts:

• Arithmetic Instructions
• Logical Instructions
• Data Transfer Instructions
• Branch Instructions and I/O, Stack, Machine Control Group Instructions

INSTRUCTIONS:

       MOV :

           This instruction is used to move the data from accumulator or memory to some registers or vice versa.

      e.g: If [A] = 00 and [B] = 20

             after MOV A,B

             [A] = 20 and [B] = 20

      MVI :

          This instruction is used to move the data from accumulator or memory to some registers or vice versa using the immediate data

e.g: after MVI B , 09

       [B] = 09

      LDA:

          This instruction is used to load the accumulator directly from the memory.

e.g: assume [4200] = FE

       after LDA 4200 

       [A] = FE

      STA :

           This instruction is used to store the content of accumulator directly to a memory address

e.g: If [A] = FF

       after STA 4200

       [4200] = FF

      LHLD :

           This instruction is used to load H&L registers directly from memory

e.g: If [4200] = FE and [4201] = 29

       after LHLD 4200

       [H] = 29 and [L] = FE

      SHLD :

           This instruction is used to store the H & L registers directly to memory.

e.g: If [H] = 29 and [L] = FE

       after SHLD 4200

       [4200] = FE and [4201] = 29

          Now we are going to see some data transfer instruction which deals with the register pair. To indicate the register pair we are using a term called ‘X’.

 LXI :

     This instruction is used to load the register pair with the immediate data.

            e.g:  after LXI H 4200

                    [H] = 42 and [L] = 00

 LDAX : 

     This instruction is used to load the accumulator with the data from address in register pair( 16 bit address).

            e.g: If [4432] = 3F and [A] = 00

                   [B]= 44 and [C]=32                      

                   after LDAX B

                   [A] = 3F

 STAX :

      This instructions is used to store the accumulator in address in register pair.

             e.g: If [A] = 32 and [D] = 40 and [E] = 00

                    after STAX D 

                    [4000] = 32.

 XCHG : 

      This instruction is used to exchange the data of H&L register pair with D&E register pair.

             e.g:  If [H] = 00, [L] = 01 and

                        [D] = 15 and [E] = 30

                     after XCHG 

                     [H] = 15 and [L] = 30

                     [D] = 00 and [E] = 01

 XTHL : 

      This instruction is used to exchange the top of stack with H&L.

             e.g: If [H] = 20 and [L] = 18 

                   assume that contents of stack is  

                  after XTHL                          

                  [H] = [01] and [L] = [09] and the contents of satck will be 

Posted in: 8085,Instruction Set,program,Rajesh