Which of the following addressing modes are suitable for...

Which of the following addressing modes are suitable for program relocation at run time? (i) Direct addressing (ii) Based register addressing (iii) $\mathrm{PC}$ -relative addressing (iv) Index register addressing (A) (i) and (ii) (B) (ii) and (iii) (C) (iii) and (iv) (D) (ii), (iii) and (iv)

Which of the following addressing modes are suitable for program relocation at run time?
(i) Direct addressing
(ii) Based register addressing
(iii) $\mathrm{PC}$ -relative addressing
(iv) Index register addressing
(A) (i) and (ii)
(B) (ii) and (iii)
(C) (iii) and (iv)
(D) (ii), (iii) and (iv)

Key Concepts

Addressing Modes

Addressing modes refer to the various methods by which computer instructions designate the data or the locations in memory to be operated on. They are fundamental in understanding how instructions interact with memory in computer architecture.

Program Relocation

Program relocation is the process that allows a computer program to be loaded into any region of memory rather than being bound to a specific memory address. This requires the use of addressing modes that enable instructions to refer to addresses in a flexible, position-independent way.

Direct Addressing

Direct addressing involves encoding the actual memory address in the instruction. While it offers straightforward access to data, it makes program relocation difficult because the hard-coded memory addresses cannot be easily adjusted when the program is moved to a different memory location.

Based Register Addressing

Based register addressing computes effective memory addresses by adding a constant offset to the contents of a base register. This mode is suitable for program relocation because the base register can be updated at runtime, allowing the relative addressing of memory locations to adapt to different memory assignments.

PC-relative Addressing

PC-relative addressing calculates the effective address by adding an offset to the current value of the program counter. This mode supports program relocation effectively, as the offset remains constant regardless of the actual memory location where the program is loaded, ensuring that the instruction pointer always reaches the correct target.

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