This set of Addressing Modes MCQ covers advanced concepts of Computer Organization and Architecture (COA) related to indexed addressing, base-register addressing, memory indirect addressing, displacement addressing, effective address calculation, and pointer implementation. Useful for GATE, IBPS IT Officer, university semester exams, and other competitive examinations.
Topic: Computer Organization & Architecture (COA) – Addressing Modes | Set: 2
Difficulty: Medium to Hard | Total Questions: 15
Addressing Modes MCQ
Q1. Which addressing mode requires two memory references to fetch an operand?
- A. Direct Addressing
- B. Memory Indirect Addressing
- C. Register Indirect Addressing
- D. Displacement Addressing
View Answer & Explanation
Answer: B
Explanation: One reference is used to get the address of the operand, and another is required to fetch the operand itself.
Q2. Indexed addressing is primarily used for:
- A. Calling subroutines
- B. Handling Array data structures
- C. Defining constants
- D. Increasing clock speed
View Answer & Explanation
Answer: B
Explanation: Effective Address = Index Register + Base Address, making Indexed Addressing ideal for traversing arrays.
Q3. Which mode helps in writing “Relocatable Code”?
- A. Direct Addressing
- B. PC-Relative Addressing
- C. Immediate Addressing
- D. Absolute Addressing
View Answer & Explanation
Answer: B
Explanation: Since addresses are calculated relative to the Program Counter (PC), the code can be relocated anywhere in memory.
Q4. In Displacement Addressing, the Effective Address is calculated as:
- A. EA = A + (R)
- B. EA = (A)
- C. EA = A + PC
- D. EA = R + PC
View Answer & Explanation
Answer: A
Explanation: Displacement Addressing combines a base address (A) with an offset stored in a register (R).
Q5. Which addressing mode is most likely used to implement “Pointers” in C/C++?
- A. Direct
- B. Register Indirect
- C. Immediate
- D. Relative
View Answer & Explanation
Answer: B
Explanation: Pointers store memory addresses, which matches the behavior of Register Indirect Addressing.
Q6. If an instruction uses 12 bits for the address, what is the maximum direct memory range?
- A. 2048 words
- B. 4096 words
- C. 1024 words
- D. 8192 words
View Answer & Explanation
Answer: B
Explanation: 212 = 4096 unique addresses can be represented.
Q7. Which mode is most expensive in terms of execution time?
- A. Register Addressing
- B. Memory Indirect Addressing
- C. Direct Addressing
- D. Immediate Addressing
View Answer & Explanation
Answer: B
Explanation: Multiple memory accesses make Memory Indirect Addressing the slowest due to higher memory access latency.
Q8. Base-Register addressing is particularly useful for:
- A. Multi-programming environments
- B. Stack operations
- C. Arithmetic operations
- D. Cache mapping
View Answer & Explanation
Answer: A
Explanation: It allows programs to be loaded into different memory segments simply by changing the base register value.
Q9. The addressing mode where the operand’s address is the sum of two registers is:
- A. Indexed
- B. Relative
- C. Based-Indexed
- D. Indirect
View Answer & Explanation
Answer: C
Explanation: Based-Indexed Addressing combines a base register and an index register for effective address computation.
Q10. Auto-decrement mode is typically used to:
- A. Implement a Queue
- B. Implement a Stack
- C. Speed up the CPU
- D. Clear the cache
View Answer & Explanation
Answer: B
Explanation: Auto-decrement decreases the pointer before access, similar to stack growth in many architectures.
Q11. Which of the following is a disadvantage of Direct Addressing?
- A. It is slow
- B. Limited address space due to instruction length
- C. Requires two memory references
- D. Difficult to implement
View Answer & Explanation
Answer: B
Explanation: The instruction format limits the number of bits available for memory addressing.
Q12. In an architecture with 16 registers, how many bits are needed for Register Addressing?
- A. 2 bits
- B. 4 bits
- C. 8 bits
- D. 16 bits
View Answer & Explanation
Answer: B
Explanation: 24 = 16, therefore 4 bits are needed to select one of sixteen registers.
Q13. Which addressing mode is used for the operand in ADD R1, (R2)?
- A. Register
- B. Direct
- C. Register Indirect
- D. Memory Indirect
View Answer & Explanation
Answer: C
Explanation: The parentheses indicate that R2 contains the memory address of the operand.
Q14. Displacement addressing is a combination of which two modes?
- A. Immediate and Direct
- B. Direct and Register Indirect
- C. Relative and Indirect
- D. Register and Immediate
View Answer & Explanation
Answer: B
Explanation: It combines a direct displacement value with a register that acts as a pointer.
Q15. Which mode allows for the largest possible address space?
- A. Direct
- B. Indirect
- C. Immediate
- D. Register
View Answer & Explanation
Answer: B
Explanation: Indirect Addressing can use a full memory word to store addresses, overcoming instruction size limitations.
Conclusion
These advanced Addressing Modes MCQ questions help strengthen concepts related to effective address calculation, indexed addressing, base-register addressing, memory indirect addressing, and pointer implementation. These concepts are frequently asked in GATE, IBPS IT Officer, university semester exams, and other technical competitive examinations.
For better understanding, practice numerical problems involving effective address computation, instruction formats, and memory access cycles.
Fore theory and concepts, refer to Addressing Modes in Computer Organization.