Matching Processor Flags to Bit Positions

This question requires matching processor status flags (List-I) with their specific bit positions in the flag register (List-II).

Understanding Standard Flag Register Assignments

Key flags and their typical bit positions in processor architectures are:

• Carry Flag (S): Indicates carry/borrow. Position: 0 ($D_0$).
• Parity Flag (Q): Indicates even parity. Position: 2 ($D_2$).
• Auxiliary Carry Flag (P): Used for BCD arithmetic. Position: 4 ($D_4$).
• Zero Flag (R): Indicates a zero result. Position: 6 ($D_6$).

Determining the Correct Match

Based on standard assignments and the provided options:

• P. Auxiliary carry flag matches with $D_4$, corresponding to option 3.
• Q. Parity flag matches with $D_2$, corresponding to option 2.
• R. Zero flag matches with $D_6$, corresponding to option 4.
• S. Carry flag matches with $D_0$, corresponding to option 1.

Final Mapping Summary

The correct pairings derived are P=3, Q=2, R=4, and S=1.

Identifying the Correct Option

This specific mapping (P=3, Q=2, R=4, S=1) aligns with Option 4, which was indicated as the correct answer.