8085 Microprocessor Instruction Flag Impact

The 8085 microprocessor utilizes status flags (Zero, Sign, Carry, Parity, Auxiliary Carry) to indicate the result of arithmetic and logical operations. Certain instructions modify these flags, while others do not.

Instruction Flag Analysis

Let's examine the effect of each given instruction on the 8085 flags:

• $RLC$: This instruction rotates the accumulator content one bit to the left. The most significant bit is moved to the Carry flag (CY), and the least significant bit. The Carry flag (CY) is affected.
• $PUSH$: This instruction pushes the contents of a register pair onto the stack. It only modifies the Stack Pointer (SP). This operation does not affect any status flags (Zero, Sign, Carry, Parity, Auxiliary Carry).
• $ORI$: This instruction performs a logical OR operation between the accumulator and an immediate data byte. The result updates the accumulator and affects the Zero (Z), Sign (S), Parity (P), Carry (CY), and Auxiliary Carry (AC) flags.
• $INR$: This instruction increments the content of a register or memory location by one. It affects the Zero (Z), Sign (S), Parity (P), and Auxiliary Carry (AC) flags. It does not affect the Carry flag (CY).

Conclusion

Based on the analysis, the $PUSH$ instruction is the only one among the options that does not alter any of the status flags in the 8085 microprocessor.