UGC NET CS 2018 July - II Question 54

Question 54

---

54. Normally user programs are prevented from handling 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. (1) I/O protection is ensured by operating system routines.
2. (2) I/O protection is ensured by a hardware trap.
3. (3) I/O protection is ensured during system configuration.
4. (4) I/O protection is not possible.

Answer: (1) I/O protection is ensured by operating system routines.

Previous	Next
UGC NET CS 2018 July - II Question 53	UGC NET CS 2018 July - II Question 55