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Electronics Engineering QUESTION #11705
Question 1
A microprocessor-based system uses memory-mapped I/O. The advantage over isolated (port-mapped) I/O is:
  • Faster I/O access due to dedicated instructions
  • I/O devices can be accessed using the full instruction set including indirect addressing✔️
  • No address decoding logic is required
  • I/O uses a separate address space, reducing conflicts
Correct Answer Explanation
In memory-mapped I/O, peripherals share the same address space as memory, so the CPU can use its complete instruction set (MOV, AND, OR, bit manipulation, indirect addressing) to access devices. In isolated I/O, only special IN/OUT instructions can access peripherals. Memory-mapped I/O simplifies programming but reduces available RAM address space.