In base register addressing mode, the effective address is calculated by…
In base register addressing mode, the effective address is calculated by adding or subtracting the value given in the instruction to the ________.
Answer: B. Base register value — Answer: Base register value. Key formula: EA = base register ± displacement (most commonly addition) What it means: The instruction provides a displacement…
- A.
Immediate value
- B.
Base register value
- C.
Index register value
- D.
Program counter value
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Correct answer: B
Answer: Base register value.
Key formula: EA = base register ± displacement (most commonly addition)
What it means: The instruction provides a displacement (address field) that is combined with the contents of a designated base register to produce the effective address used to access memory.
Variation: Some architectures allow subtracting the displacement; when subtraction is used the instruction specifies that behaviour. Commonly, the displacement is added.
Contrast with other modes: Immediate addressing places the operand value in the instruction (not an address). Indexed addressing uses an index register to modify an address. PC-relative addressing uses the program counter plus a displacement, not the base register.
Simple example: If the base register contains 0x1000 and the displacement in the instruction is 0x20, the effective address is 0x1020.