Tip:A–D to answerE for explanationV for videoS to reveal answer
To access the I/O devices, the status flag is continuously checked in
- A.
Program controlled I/O
(Correct Answer) - B.
Memory mapped I/O
- C.
I/O mapped
- D.
None of these
Correct Answer: Program controlled I/O
Explanation
Calculation
The method where the CPU repeatedly checks the status flag of an I/O device is:
CPURepeatCheck Status Register
If Status=Ready⟹Data Transfer
If Status=Busy⟹Loop Back to Check
This cycle of continuous checking is represented as:
Efficiency∝Waiting Time1
Answer: Programmed I/O (specifically Polling)
Explanation
Calculation
The method where the CPU repeatedly checks the status flag of an I/O device is:
CPURepeatCheck Status Register
If Status=Ready⟹Data Transfer
If Status=Busy⟹Loop Back to Check
This cycle of continuous checking is represented as:
Efficiency∝Waiting Time1
Answer: Programmed I/O (specifically Polling)
