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19 votes
19 votes
State whether the following statements are TRUE or FALSE with reason:

The data transfer between memory and I/O devices using programmed I/O is faster than interrupt-driven I/O.
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4 Answers

48 votes
48 votes
Best answer

$\text{False}$ because in programmed I/O, CPU will check the I/O devices' status according to written program. Suppose CPU requested  $5$ I/O devices and the program is written to check sequentially and 5$^{th}$ device is ready before 2$^{nd}$ device, then also CPU will come to check at its turn.

So, programmed I/O doesn't care about availability status of devices. it blindly works according to written program. That's why it is slow.

Interrupt driven I/O :  Here, if any device is ready then it won't wait for CPU, it will say to CPU that "I am ready" by sending interrupt request and the delay here will be only "time taken in servicing the interrupt"  which is less than programmed I/O.

So, the answer is FALSE.

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2 Comments

well explained  !!
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False. 

In programmed IO, IO operations are programmed in the CPU. CPU will be waiting until IO operation is completed. Hence, CPU utilisation is very poor and the CPU time depends on the speed of the IO DEVICE and amount of data to be transferred. 

Whereas, in Interrupt driven IO, IO operations are controlled by the IO Interface chip. Hence, processor utilisation is efficient. CPU time depends on the latency of the IO Interface Chip rather than speed of IO Device which is much slower than IO interface chip speed.

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3 votes
3 votes
ANS: False

Explanation:

As in programmed I/O the processor has to wait a long time for the I/O module of concern to be reads for either reception or transmission of data, while in interrupt driven I/O CPU is in waiting state when interrupt comes. So takes less time to transfer the data and in interrupt driven I/O, the interface between memory and I/O works like a CPU.
–2 votes
–2 votes
FALSE
data transfer in interrupt driven I/O is faster than programmed I/O

2 Comments

I think data transfer is same in all case. Becoz data transfer rate depends on the bus.

only major factor among all of them is CPU intervention
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How come data transfer is fast in case of Interrupt driven I/O?
The major chunk of time in data transfer time is decided by the bandwidth of the I/O device and the amount of data to be transferred. And we use Interrupt driven I/O technique to save on the cpu time which is wasted in checking device status continuously in case of programmed I/O.
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–2 votes
–2 votes
in programmed io no interface register but in interrupt driven io interface reg is use so interrupt deriven is faster then programmed io
Answer:

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