Consider the following statements : (i) Auto increment addressing mode is…
2018
Consider the following statements :
(i) Auto increment addressing mode is useful in creating self-relocating code.
(ii) If auto increment addressing mode is included in an instruction set architecture, then an additional ALU is required for effective address calculation.
(iii) In auto incrementing addressing mode, the amount of increment depends on the size of the data item accessed.
Which of the above statements is/are true?
- A.
(i) and (ii) only
- B.
(ii) and (iii) only
- C.
(iii) only
- D.
(ii) only
Attempted by 254 students.
Show answer & explanation
Correct answer: C
Final answer: Only statement (iii) is true.
Explanation:
Statement (i): False. Auto-increment addressing is designed to simplify sequential access to data structures (for example, stepping through array elements). Self-relocating or position-independent code is usually achieved with PC-relative addressing or relocation techniques, not by auto-increment addressing.
Statement (ii): False. Supporting auto-increment does not inherently require adding a separate full ALU. The increment can be performed by a small dedicated incrementer or by reusing the processor's existing address-generation logic or ALU; a separate additional ALU is not a necessary condition.
Statement (iii): True. The amount by which the address register is incremented depends on the size of the data item being accessed. For example, access to bytes increments by 1, access to 16-bit words increments by 2, and access to 32-bit words increments by 4.
Summary: Only the statement that the increment amount depends on data size is correct; the other two statements are not generally true.
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