Analysis of Statements

The question asks to evaluate two statements about the 8051 microcontroller: Assertion A regarding full-duplex transmission and Reason R regarding bit-addressable I/O ports.

Evaluating Assertion A: Full-Duplex Transmission

• The 8051 microcontroller includes a built-in Universal Asynchronous Receiver/Transmitter (UART) for serial communication.
• UART supports full-duplex communication, meaning data can be transmitted and received simultaneously using separate transmit (TXD) and receive (RXD) lines.
• Therefore, Assertion A is correct.

Evaluating Reason R: Bit-Addressable I/O Ports

• The 8051 architecture features I/O ports (P0, P1, P2, P3) where individual bits can be accessed and controlled directly.
• This feature is known as bit-addressability.
• Therefore, Reason R is correct.

Evaluating the Relationship between A and R

• Assertion A is about the capability of the 8051's serial communication interface (UART).
• Reason R describes a general characteristic of the 8051's I/O ports.
• While the TXD and RXD pins used for full-duplex communication are part of the I/O ports, the reason for full-duplex capability lies in the UART's design (simultaneous transmit/receive logic), not inherently in the bit-addressability of the ports themselves.
• Bit-addressability is a general I/O feature, while full-duplex is a specific communication protocol feature enabled by dedicated hardware (UART).
• Thus, Reason R is correct but does not provide the correct explanation for Assertion A.

Conclusion

Based on the analysis:

• Assertion A is correct.
• Reason R is correct.
• Reason R is NOT the correct explanation of Assertion A.

This corresponds to Option 2.