ACtE04 · Chapter 4Computer Organization & Embedded Systems🏛️ Past Licensure QuestionID: 8dcc89fa
In memory-mapped I/O architecture, which statement is correct?
In memory-mapped I/O architecture, which statement is correct?
Multiple Choice Options
- A✓ Correct Option
Memory and I/O devices share the same contiguous address space
- B
I/O devices reside in a completely isolated separate address space requiring special IN/OUT instructions
- C
The CPU cannot access I/O devices directly through memory reference instructions
- D
Hardware requires dedicated control lines for I/O distinct from memory
Detailed Technical Solution & Explanation
In memory-mapped I/O, I/O device registers are mapped directly into the standard memory address space. The CPU accesses I/O ports using standard memory instructions (MOV, LDA, STA) and standard memory read/write control signals (MEMR, MEMW), meaning memory and I/O share a single unified address space.
Option Analysis:
•
Option A (Memory and I/O share the same address space): Correct; foundational definition of memory-mapped I/O.
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Option B (Isolated address space): Describes Isolated (I/O-mapped) I/O.
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Option C (CPU cannot access I/O via memory instructions): False; memory instructions are the only way I/O is accessed.
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Option D (Dedicated I/O control lines required): False; memory control lines are reused.
Reference: Demo2 · Set 2NEC Licensure Syllabus