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Which of the statements below are true? Which are false?

a. In polling, I/O devices set flags that must be periodically checked by the CPU.
b. When using interrupts, the CPU interrupts I/O devices when an I/O event happens.
c. The overhead of polling depends on the polling frequency.
d. Polling is often a viable option for slow and asynchronous devices.
e. Synchronous I/O cannot be done with interrupts.
f. User processes are always blocked during asynchronous I/O operations.
g. Traps are software-generated interrupts.
h. System-calls can be implemented using either traps or polling.
i. DMA usually improves the overall system performance.
j. DMA is necessary for asynchronous I/O transfers

Respuesta :

Answer:

a. True

b. False

c. False

d. True

e. True

f. True

g. False

h. True

i. False

j. False

Explanation:

Polling is a technique in which users are connect externally and programs are run by synchronization activity. The users are allowed to set flags for devices which are periodically checked. The end user can implement system calls using the polling technique.

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