ITPEC FE Morning April 2018 Question 9

Relative Addressing — effective address = program counter + offset.

The question asks which mode adds the program counter (PC) value to the address part of the instruction.

• •Relative addressing — effective_address = PC + offset; used for position-independent code and branch instructions
• •Absolute addressing — address is taken directly from the instruction, no addition
• •Base addressing — effective_address = base_register + offset; uses a dedicated base register, not PC
• •Indexed addressing — effective_address = index_register + offset; uses an index register for array traversal

Why not others:
- (a) Absolute — no register involved; the instruction contains the full address
- (b) Base — uses a base register, not the program counter
- (c) Indexed — uses an index register, not the program counter

Key rule: If the question mentions "program counter" or "instruction address register," the answer is always Relative addressing.

AI-generated — may contain errors