Q. Which of the subsequent instructions should be privileged?
a) Read the clock
b) Clear memory
c) Set value of timer
d) Issue a trap instruction
e) Turn off interrupts
f) Modify entries in device-status table
g) Switch from user to kernel mode
h) Access I/O device
Answer: The following operations require to be privileged: clear memory, Set value of timer, turn off interrupts and modify entries in device-status table and access I/O device. The rest are able to be performed in user mode.