Skip to content
Related Articles

Related Articles

Improve Article
Save Article
Like Article

GATE | GATE-CS-2005 | Question 69

  • Last Updated : 10 Sep, 2018

A device with data transfer rate 10 KB/sec is connected to a CPU. Data is transferred byte-wise. Let the interrupt overhead be 4 microsec. The byte transfer time between the device interface register and CPU or memory is negligible. What is the minimum performance gain of operating the device under interrupt mode over operating it under program controlled mode?
(A) 15
(B) 25
(C) 35
(D) 45

Answer: (B)

Explanation: In programmed I/O, CPU does continuous polling,
To transfer 1B CPU polls for 10^-4 sec = 10^2 micro-sec of processing
In interrupt mode CPU is interrupted on completion of i\o,
To transfer 1B CPU does 4 micro-sec of processing(since transfer time between other components is negligible).
Gain = 10^2 / 4 = 25

Quiz of this Question

Attention reader! Don’t stop learning now.  Practice GATE exam well before the actual exam with the subject-wise and overall quizzes available in GATE Test Series Course.

Learn all GATE CS concepts with Free Live Classes on our youtube channel.

My Personal Notes arrow_drop_up
Recommended Articles
Page :

Start Your Coding Journey Now!