Question
Consider a hypothetical processor with an instruction of type LW R1, 20(R2), which during execution reads a 32-bit word from memory and stores it in a 32-bit register R1. The effective address of the memory location is obtained by the addition of a constant 20 and the contents of register R2. Which of the following best reflects the addressing mode implemented by this instruction for the operand in memory?
Official answer and solution
- Official answer
- D
- From
- Official GATE 2011 answer key
Solution
Identify addressing mode definitions where effective address equals base register contents plus an immediate offset.
- The instruction
LW R1, 20(R2)computes the effective address as .
- In computer architecture, an addressing mode where an address is formed by adding an immediate displacement (constant offset) to the contents of a base register is known as base-displacement or base indexed addressing.
- Option D (Base Indexed Addressing) represents this addressing format.
D
The answer is the one in the official GATE answer key. The solution is this site's own explanation.
Source
- Paper
- GATE 2011 Computer Science and Information Technology (CS)
- Question
- 21 of 65, printed as CS Q.21
- Section
- Computer Science and Information Technology
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