8051 logical OR practice — OR with zero (immediate) Compute the accumulator after these two instructions (shown with real newlines). Assume immediate OR with zero (#00H): MOV A, #2BH ORL A, #00H

Introduction / Context:
This checks understanding of the ORL instruction and the difference between immediate and direct addressing. ORing any value with 00H (immediate) leaves the value unchanged; ORing with a direct address would depend on that RAM location's content.

Given Data / Assumptions:

• The code sequence is interpreted as immediate OR: ORL A, #00H.
• MOV A, #2BH loads 0x2B (binary 0010 1011) into A.
• OR with 0x00 immediate should not modify the accumulator.

Concept / Approach:
OR rules: x OR 0 = x. Immediate addressing (prefixed with #) uses the literal constant. Therefore, A remains 0x2B after ORL A, #00H.

Step-by-Step Solution:

Verification / Alternative check:
Binary check: 0010 1011 OR 0000 0000 = 0010 1011 (unchanged).

Why Other Options Are Wrong:

• 1B H, 3B H, 4B H: these would require setting or clearing specific bits, which does not happen when ORing with zero.

Common Pitfalls:
Confusing immediate with direct addressing. Without the #, ORL A, 00H would OR with RAM location 00H (R0 in Bank 0), yielding an unknown result unless that memory value is specified.

Final Answer:
2B H