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COMPUTER ORGANISATION

• TOPIC:DATA TRANSFER INSTRUCTIONS

• Group:- G2 BATCH:-B3• MADE BY:15CP032-SIDDHAPURA

ROMIL 15CP018-AHALPARA KEVAL 15CP033-KAVAIYA HIREN

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8085 Microprocessor• The microprocessor is a programmable integrated device that has computing and decision making capability similar to that CPU of a computer.• It is a multi-purpose,clock- driven, register-based electronic device.

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LET’S BEGIN WITH MAIN DATA TRANSFER INSTRUCTIONS

• One of the primarily functions of microprocessor is copying data from source register to destination register.

• This copying function is labeled as data transfer instructions.

• In fact, contents of the source are not transferred but are copied into destination without modyfying the content of source.

• The previous contents of destination are replaced by the contents by the contents of the source.

• Several instruction are used to copy data which are listed below:-

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LIST OF DATA TRANSFER INSTRUCTION

• MOV Rd,Rs:- Copies data from source register Rs to destination register Rd.

• MVI R,8-bit:- Loads the 8-bit of the second byte into the register specified.• OUT 8-bit port address:- Sends the contents of the

accumulator (A) to the output port specified in the second byte.

• IN 8-bit port address:-Accepts the data from the input port specified in second byte ,and loads into the accumulator.

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“LHLD” INSTRUCTION• LHLD stands for Load H and L Registers Direct .• This instruction copies the contents of the memory

location pointed by the 16-bit address in register L and copies the contents of the next memory location in register H. The contents of source memory locations are not altered.

• Flags:- The execution of LHLD instruction can not affect the flags.

• Example:- Assume memory allocation 1050H contains 30H and 1051H contains 32H.This instruction transfer memory contents to register pair HL.

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• For above example Instruction :- LHLD 1050H Hex code :- 2A 50 10

• Memory contents before instruction:-

• Registers contents after instruction:-

1050 301051 32

H 32L 30

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LHLD timing diagram

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• In 1st Machine cycles, the 8085 microprocessor places the address of memory loaction on the address bus and fetches the opcode of LHLD instruction.

• The second machine cycle is read. In this machine cycle processor places the address of next incremented memory location and gets the low-order byte.

• The third machine cycle is also read. This machine cycle also perform the same as second machine cycle and gets the high-order byte instead of low-order byte.

• In the fourth machine cycle, contents of the memory location pointed out by 16-bit address copies into register L.

• In the fifth machine cycle, contents of the next memory location copies into register H.

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Number of bytes used in instruction:- 3 bytes

Total no. of machine cycles:- 5(F,R,R,R,R) Total no. of clock cycles:-16Addressing modes:-Register direct

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“SHLD” INSTRUCTION• SHLD stands for store H and L Registers Direct.• The contents of register L are stored in the memory

location specified by the 16- bit address in the operand, and the contents of H registers are stored in the next memory location by incrementing the operand.

• Remember, the contents of the HL pair register are not altered.

• This is also a 3-byte instruction. The second byte specifies the low-order address and the third byte specifies the high-order address.

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• Flags:- No flags are affected.• Example:-Assume the H and L registers contain 01H and

FFH, respectively at memory location 1050H and 1051H.• Instruction:- SHLD 1050H Hex code:- 22 50 10 • Register contents before instruction:-

• Register and memory contents before instruction:-

H 01L FF

1050 FF1051 01

H 01L FF

12SHLD timing diagram

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• In SHLD instruction, first 3 cycle is same as in described in LHLD instruction.

• In SHLD instruction, 4th and 5th cycle will be write cycle.• So, in 4th cycle, contents of the register L are stored in

the memory pointed by the address in operand, and during 5th machine cycle,contents of the register H are stored in next memory location.

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Number of bytes used in instruction:- 3 bytes

Total no. of machine cycles:- 5 (F,R,R,W,W)

Total no. of clock cycles:-16Addressing modes:-Register direct

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Thank you…!!!!