Multiple choice

Normally user programs are prevented from handing I/O directly by I/O instructions in them. For CPUs having explicit I/O instructions, such I/O protection is ensured by having the I/O instructions privileged. In a CPU with memory mapped I/O, there is no explicit I/O instruction.

Which one of the following is true for a CPU with memory mapped I/O?

  1. I/O protection is ensured by operating system routine(s)

  2. I/O protection is ensured by a hardware trap

  3. I/O protection is ensured during system configuration

  4. I/O protection is not possible

Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In memory mapped I/0 the complete system (memory + I/0 ports) hold the same set of addresses. They are considered to be the part of that memory only. This management is done by OS only.

Keep practicing — related questions