![ADI(ADD IMMEDIATE WITH DATA)
This is a 2 byte instruction.
The contents of the accumulator register are added with immediate 8-bit data using the ADI
instruction. The sum is thus stored in the accumulator. All flags are correspondingly
modified...
Example : ADI 05H
6
The Opcode The Operand Description
ADI 8-bit immediate data
Add immediate value to the
accumulator
[A] <- [A] + data](https://image.slidesharecdn.com/10-200713192049/85/ARITHMETIC-OPERATIONS-IN-8085-MICROPROCESSOR-6-320.jpg)
ARITHMETIC OPERATIONS IN 8085 MICROPROCESSOR
- 1. B.RAMA PRABHA ASSISTANT PROFESSOR, DEPARTMENT OF COMPUTER SCIENCE, K.C.S.KASI NADAR COLLEGE OF ARTS & SCIENCE, CHENNAI-21
- 2. ARITHMETIC OPERATIONS The 8085 microprocessor performs various arithmetic operations such as addition, subtraction, increment and decrement operations. These arithmetic operations have the following mnemonics. ADD – Add (Add the content of a register) ADI – Add Immediate (Add 8 bit data) SUB – Subtract (Subtract the content of a register) SUI – Subtract Immediate (subtract 8 bit data) INR – Increment (Increase the content of register by 1) DCR – Decrement(Decrease the content of register by 1) 2
- 3. Addition in 8085 Any 8-bit value, or the contents of any register, or even the contents of a memory location pointed by HL pair, can be summed up with the contents of the accumulator register. The added value, i.e., the result is then stored in the accumulator register itself. This function cannot be be used for two other registers together – the addition has to be performed with the accumulator being one of the addends. Thus, for example, the contents of, say, register C cannot be summed up directly to the contents of register B. 3
- 4. ADD This is a 1 byte instruction. As discussed earlier, the contents of any register or memory location are added to the contents of the accumulator register. The corresponding sum is then saved in the accumulator. If the second addend is a memory, its address is specified by the H-L pair. All flags linked with the addition are updated with the result of the addition performed. Example : ADD B 4 The Opcode The Operand Description ADD R Add register to the accumulator M Add contents from the location pointed by the HL pair (M) to the contents of the accumulator
- 5. ADC(ADD WITH CARRY) This is a 1 byte instruction. The only difference between the ADD and the ADC operations is that the ADC condition considers the carry value as well. Thus, the Carry flag plays an important role and becomes the third addend.. Example : ADC B 5 The Opcode The Operand Description ADC R Add register to the accumulator with carry M Add the content of the location pointed by the value in the HL pair (M) to the accumulator with carry.
- 6. ADI(ADD IMMEDIATE WITH DATA) This is a 2 byte instruction. The contents of the accumulator register are added with immediate 8-bit data using the ADI instruction. The sum is thus stored in the accumulator. All flags are correspondingly modified... Example : ADI 05H 6 The Opcode The Operand Description ADI 8-bit immediate data Add immediate value to the accumulator [A] <- [A] + data
- 7. DAD(ADD 16 BIT DATA) This is a 2 byte instruction. The 16-bit contents of any 8085 register pair are added to the contents of the H-L register pair. The result is also stored in the H-L pair. The carry flag is also updated with the result of the addition operation. No other flag bits are affected. Example : DAD B 7 The Opcode The Operand Description DAD Register pair Add contents of register pair to contents of H-L pair. The result is stored in the H-L pair.
- 8. Subtraction in 8085 Any 8-bit value, or the contents of any register, or even the contents of a memory location can be subtracted from the contents of the accumulator register. The difference of this operation is stored in the accumulator. The subtraction is performed in 2’s complement form. (You can revisit the concept of 2’s complement over here.) Also, if the result of the subtraction is negative, it is stored in its 2’s complement form. Similar to the addition operation, no two 8-bit registers can be subtracted directly, unless it is subtracted from the accumulator. 8
- 9. SUB(SUBTRACT TO THE REGISTER) This is a 1 byte instruction. The contents of any register or memory location are subtracted from the contents of the accumulator register. The corresponding difference is then saved in the accumulator register. If the operand is a memory, its address is specified by the H-L pair. All flags linked with the subtraction operation are updated with the result of the operation performed. Example : SUB B 9 The Opcode The Operand Description SUB R Subtract register from the accumulator M Subtract contents of the location pointed by HL pair (M) from the accumulator
- 10. SBB(SUBTRACT TO THE REGISTER WITH BORROW) This is a 1 byte instruction. The contents of any register or memory location AND the borrow value (the CY flag in this case) are subtracted from the contents of the accumulator register. The corresponding difference is saved in the accumulator register. If the operand is a memory, its address is specified by the H-L pair. Example : SBB B 10 The Opcode The Operand Description SBB R Subtract register from the accumulator with borrow considered M Subtract the contents of the location pointed by the HL pair (M) from the accumulator with borrow considered
- 11. SUI(SUBTRACT IMMEDIATE WITH DATA) This is a 2 byte instruction. The contents of the accumulator register are subtracted with immediate 8-bit data using the SUI instruction. The answer is thus stored in the accumulator. All flags are correspondingly modified to reflect the difference Example : SUI 04H 11 The Opcode The Operand Description SUI 8-bit immediate data Subtract an immediate value from the accumulator
- 12. SBI(SUBTRACT IMMEDIATE WITH BORROW) This is a 2 byte instruction. The contents of the accumulator register are subtracted with immediate 8-bit data AND the borrow value (specified by the CY flag) using the SBI instruction. The answer is thus stored in the accumulator. All flags are correspondingly modified to reflect the difference. Example : SBI 04H 12 The Opcode The Operand Description SBI 8-bit immediate data Subtract an immediate value from the accumulator with Borrow considered
- 13. SBI(SUBTRACT IMMEDIATE WITH BORROW) This is a 2 byte instruction. The contents of the accumulator register are subtracted with immediate 8-bit data AND the borrow value (specified by the CY flag) using the SBI instruction. The answer is thus stored in the accumulator. All flags are correspondingly modified to reflect the difference. Example : SBI 04H 13 The Opcode The Operand Description SBI 8-bit immediate data Subtract an immediate value from the accumulator with Borrow considered
- 14. Increment or Decrement in 8085 Every register or memory location holds contents of size 8-bits. These contents can be incremented and/or decremented by a value of 1. If we consider register pairs, then the 16-bit contents can also be incremented or decremented by a value of 1. 14
- 15. INR(INCREMENT BY 1) This is a 1 byte instruction. The INR command is used to increment/increase the contents of a register or of the data at the location pointed by HL pair(M) by one. The result is stored in the same location itself. In the case of the operand being M, the value at the memory location given by the HL pair is incremented by one. The value in the HL register pair does not change. Example : INR B ,INR 1250M 15 The Opcode The Operand Description INR R Increment Register contents by one M Increment the content at the memory location pointed by the HL pair by one
- 16. INX(INCREMENT REGISTER PAIR BY 1) This is a 1 byte instruction. The INX instruction increments the contents of a register-pair by the value of one. The result is stored in the same place itself. Example : INX H 16 The Opcode The Operand Description INX R Increment contents of register pair by one
- 17. DCR(DECREMENT BY 1) This is a 1 byte instruction. The DCR command is used to decrement/decrease the contents of a register or of a memory location by the value of one. The result after this operation is stored in the same location itself. If the operand happens to be a memory location, its address is then specified by the contents of the H-L pair. Example : DCR B , DCR 1250M 17 The Opcode The Operand Description DCR R Decrement Register contents by one M Decrement the content at the memory location pointed by the HL pair by one
- 18. DCX(DECREMENT REGISTER PAIR BY 1) This is a 1 byte instruction. The DCX instruction decrements the contents of the register-pair by the value of one. The result is stored in the same place itself. Example : DCX H 18 The Opcode The Operand Description DCX R Decrement register pair by one
- 19. “ 19