Arithmetic and logical instructions
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This document describes various arithmetic and logical instructions that can be performed on the 8086 microprocessor. It provides the opcode, operand, and description for instructions such as addition, subtraction, increment, decrement, AND, OR, XOR, rotate, compare, and complement. Examples are given for each instruction type. The document is intended to provide guidance on these fundamental instruction types under the supervision of a listed professor and includes names of students.
Arithmetic and logical instructions
- 1. Birla Vishwakarma Mahavidyalaya ET Department Arithmetic Instructions and Logical Instructions Under the Guidance : Prof. Bhargav Goradiya, H.O.D. ,ET department,BVM
- 2. Name E. No. Vatsal Bodiwala 140083112002 Ashit Patel 140083112010 Jigar Sindha 140083112017 Vipul Thakor 140083112019 Rohit Vadgama 140083112020
- 3. Addition Subtract Increment Decrement
- 4. Any 8-bit number, or the contents of register, or the contents of memory location can be added to the contents of accumulator. The result (sum) is stored in the accumulator. No two other 8-bit registers can be added directly. If the operand is memory location, its address is specified by H-L pair.
- 5. Opcode Operand Description ADD R M Add content of register or memory to accumulator Example: ADD B or ADD M Example: ADC B or ADC M Opcode Operand Description ADC R M Add register or memory to accumulator with carry
- 6. Opcode Operand Description ADI 8-Bit Data Add immediate to accumulator Opcode Operand Description ACI 8-Bit data The 8-bit data and the Carry Flag (CY) are added to the contents of accumulator. Example: ADI 45 H Example: ACI 45 H
- 7. Opcode Operand Description DAD Register pair Add register pair to H-L pair The 16-bit contents of the register pair are added to the contents of H-L pair. The result is stored in H-L pair. If the result is larger than 16 bits, then CY is set. Example: DAD B
- 8. Any 8-bit number, or the contents of register, or the contents of memory location can be subtracted from the contents of accumulator. The result is stored in the accumulator. Subtraction is performed in 2’s complement form. If the result is negative, it is stored in 2’s complement form. No two other 8-bit registers can be subtracted directly. If the operand is memory location, its address is specified by H-L pair.
- 9. Opcode Operand Description SUB R M The contents of the register or memory location are subtracted from the contents of the accumulator. Example: SUB B or SUB M Opcode Operand Description SBB R M The contents of the register or memory location and Borrow Flag are subtracted from the contents of the accumulator. Example: SBB B or SBB M
- 10. Opcode Operand Description SUI 8-bit data The 8-bit data is subtracted from the contents of the accumulator. Example: SUI 5 H Opcode Operand Description SBI 8-bit data The 8-bit data and the Borrow Flag is subtracted from the contents of the accumulator. Example: SBI 5 H
- 11. The 8-bit contents of a register or a memory location can be incremented or decremented by 1. The 16-bit contents of a register pair can be incremented or decremented by 1. Increment or decrement can be performed on any register or a memory location. If the operand is a memory location, its address is specified by the contents of H-L pair.
- 12. Opcode Operand Description INR R M The contents of register or memory location are incremented by 1. Example: INR B or INR M Opcode Operand Description INX R The contents of register pair are incremented by 1. Example: INX H
- 13. Opcode Operand Description DCR R M The contents of register or memory location are decremented by 1. Example: DCR B or DCR M Opcode Operand Description DCX R The contents of register pair are decremented by 1. Example: DCX H
- 14. These instructions perform various logical operations with the content of accumulator. The logical operations are: AND OR XOR Rotate Compare Complement
- 15. Any 8-bit data, or the contents of register, or memory location can logically have AND operation OR operation XOR operation with the contents of accumulator. The result is stored in accumulator.
- 16. Opcode Operand Description ANA R M Logical AND register or memory with accumulator The contents of the accumulator are logically ANDed with the contents of register or memory. The result is placed in the accumulator. If the operand is a memory location, its address is specified by the contents of H-L pair. S, Z, P are modified to reflect the result of the operation. CY is reset and AC is set. Example: ANA B or ANA M.
- 17. Opcode Operand Description ANI 8-bit data Logical AND immediate with accumulator The contents of the accumulator are logically ANDed with the 8-bit data. The result is placed in the accumulator. S, Z, P are modified to reflect the result. CY is reset, AC is set. Example: ANI 86H.
- 18. Opcode Operand Description ORA R M Logical OR register or memory with accumulator The contents of the accumulator are logically ORed with the contents of the register or memory. The result is placed in the accumulator. If the operand is a memory location, its address is specified by the contents of H-L pair. S, Z, P are modified to reflect the result. CY and AC are reset. Example: ORA B or ORA M.
- 19. Opcode Operand Description ORI 8-bit data Logical OR immediate with accumulator The contents of the accumulator are logically ORed with the 8-bit data. The result is placed in the accumulator. S, Z, P are modified to reflect the result. CY and AC are reset. Example: ORI 86H.
- 20. Opcode Operand Description XRA R M Logical XOR register or memory with accumulator The contents of the accumulator are XORed with the contents of the register or memory. The result is placed in the accumulator. If the operand is a memory location, its address is specified by the contents of H-L pair. S, Z, P are modified to reflect the result of the operation. CY and AC are reset. Example: XRA B or XRA M.
- 21. Opcode Operand Description XRI 8-bit data XOR immediate with accumulator The contents of the accumulator are XORed with the 8-bit data. The result is placed in the accumulator. S, Z, P are modified to reflect the result. CY and AC are reset. Example: XRI 86H.
- 22. Any 8-bit data, or the contents of register, or memory location can be compares for: Equality Greater Than Less Than with the contents of accumulator. The result is reflected in status flags.
- 23. The contents of the operand (register or memory) are compared with the contents of the accumulator. Both contents are preserved . The result of the comparison is shown by setting the flags of the PSW as follows: Opcode Operand Description CMP R M Compare register or memory with accumulator
- 24. if (A) < (reg/mem): carry flag is set if (A) = (reg/mem): zero flag is set if (A) > (reg/mem): carry and zero flags are reset. Example: CMP B or CMP M Opcode Operand Description CMP R M Compare register or memory with accumulator
- 25. The 8-bit data is compared with the contents of accumulator. The result of the comparison is shown by setting the flags of the PSW as follows: Opcode Operand Description CPI 8-bit dat Compare immediate with accumulator
- 26. if (A) < data: carry flag is set if (A) = data: zero flag is set if (A) > data: carry and zero flags are reset. Example: CPI 89H Opcode Operand Description CPI 8-bit dat Compare immediate with accumulator
- 27. Each bit in the accumulator can be shifted either left or right to the next position. Opcode Operand Description RLC None Rotate accumulator left Each binary bit of the accumulator is rotated left by one position.
- 28. Bit D7 is placed in the position of D0 as well as in the Carry flag. CY is modified according to bit D7. S, Z, P, AC are not affected. Example: RLC.
- 29. Opcode Operand Description RRC None Rotate accumulator right Each binary bit of the accumulator is rotated right by one position. Bit D0 is placed in the position of D7 as well as in the Carry flag. CY is modified according to bit D0. S, Z, P, AC are not affected. Example: RRC.
- 30. Opcode Operand Description RAL None Rotate accumulator left through carry Each binary bit of the accumulator is rotated left by one position through the Carry flag. Bit D7 is placed in the Carry flag, and the Carry flag is placed in the least significant position D0. CY is modified according to bit D7. S, Z, P, AC are not affected. Example: RAL.
- 31. Opcode Operand Description RAR None Rotate accumulator right through carry Each binary bit of the accumulator is rotated right by one position through the Carry flag. Bit D0 is placed in the Carry flag, and the Carry flag is placed in the most significant position D7. CY is modified according to bit D0. S, Z, P, AC are not affected. Example: RAR.
- 32. The contents of accumulator can be complemented. Each 0 is replaced by 1 and each 1 is replaced by 0.
- 33. Opcode Operand Description CMA None Complement accumulator The contents of the accumulator are complemented. No flags are affected. Example: CMA. Opcode Operand Description CMC None Complement carry The Carry flag is complemented. No other flags are affected. Example: CMC.
- 34. Opcode Operand Description STC None Set carry The Carry flag is set to 1. No other flags are affected. Example: STC.