Open In App

UGC-NET | UGC NET CS 2015 Jun – III | Question 1

Like Article
Like
Save Article
Save
Share
Report issue
Report

For the 8 – bit word 00111001, the check bits stored with it would be 0111. Suppose when the word is read from memory, the check bits are calculated to be 1101. What is the data word that was read from memory?
(A) 10011001
(B) 00011001
(C) 00111000
(D) 11000110


Answer: (B)

Explanation: 8 – bit word = 00111001, Check bits = 0111.
There are four bits and it’s position will be
20 = 1; i.e. p1 = 1
21 = 2; i.e. p2 = 1
22 = 4; i.e. p4 = 1
23 = 8; i.e. p8 = 0.
Encoded string will be:
d12 = 0; d11 = 0; d10 = 1; d9 = 1; d8 = p8 = 1; d7 = 1; d6 = 0; d5 = 0; d4 = p4 = 1; d3 = 1; d2 = p2 = 1; d1 = p1 = 1.
i.e.
d12 = 0; d11 = 0; d10 = 1; d9 = 1; d8 = 1; d7 = 1; d6 = 0; d5 = 0; d4 = 1; d3 = 1; d2 = 1; d1 = 1.
Check bits at other end = 1101.
XOR(0111, 1101) = 1010. 10th bit be change.
So, new encoded string will be:
d12 = 0; d11 = 0; d10 = 0; d9 = 1; d8 = 1; d7 = 1; d6 = 0
d5 = 0; d4 = 1; d3 = 1; d2 = 1; d1 = 1.
And the data word that was read from memory will be – 00011001.
So, option (B) is correct.


Quiz of this Question


Last Updated : 20 Jun, 2018
Like Article
Save Article
Previous
Next
Share your thoughts in the comments
Similar Reads