Addressing Modes: Statement Analysis

This question requires identifying the incorrect statement regarding various CPU addressing modes commonly used in computer architecture.

Evaluating Addressing Mode Statements

• Immediate Addressing: This mode places the operand directly within the instruction itself. As it doesn't require an extra memory fetch to retrieve the operand, it generally speeds up execution, making the statement 'Immediate addressing reduces memory access time' correct.
• Index Addressing: This mode calculates the effective address by adding the contents of an index register to a base address specified in the instruction. It is highly efficient for accessing elements within arrays or tables, confirming that 'Index addressing is used for accessing array elements' is correct.
• Register Indirect Addressing: In this mode, the instruction specifies a register that contains the memory address of the operand. This allows the processor to access data indirectly through a pointer stored in a register, validating that 'Register indirect addressing allows accessing memory via a pointer' is correct.
• Relative Addressing: This mode computes the effective address by adding an offset (usually from the instruction) to the current value of the Program Counter (PC). This technique is very common for implementing branch instructions (like jumps and conditional jumps) because it allows specifying targets relative to the current instruction's location. Therefore, the statement 'Relative addressing cannot be used for branch instruction' is fundamentally incorrect.

Conclusion on Incorrect Statement

Based on the analysis, the statement that is not correct is that relative addressing cannot be used for branch instructions. In fact, it is a primary method for implementing them.