DI Test 91
Directions for Questions from 1 to 5:
Answer the questions on the basis of the information given
A machine recognises inputs only in the form of a string of bits to produce the products. It reads
the string of bits from left to right. A bit could be only of two forms 0 or 1.
1. In the communication of input with the machine, it is possible that at most one bit-reversal
happens due to errors in the communication channel. Bit-reversal refers to 1 changing into 0
or 0 changing into 1. To check at most one such bit-reversal, a parity bit is appended at the
rightmost end of the input. Parity bit is not an instruction to the machine to do anything but
just a check if the input has been read appropriately by the machine or not. The following
algorithm should be followed for the check.
Step 1: Compute the parity bit for the input using a defined procedure.
Step 2: Append it at the end of the input and send it to the machine.
Step 3: Machine reads the input and computes parity bit using the same defined procedure.
Step 4: If parity bit supplied is equal to the parity bit computed, execute the input.
Step 5: If parity bit supplied is different from the parity bit computed, request a re-sending of
Which of the following defined procedures of setting up the value of parity bit is in accordance
with the machine’s behaviour?
Set the parity bit to 0. Reverse the parity bit for each occurrence of bit 1 in the input
Set the parity bit to 1. Reverse the parity bit for each occurrence of bit 1 in the input.
Set the parity bit to 1. Reverse the parity bit if the number of times bit 1 occurs in the input
Set the parity bit to 0. Reverse the parity bit if the number of times bit 0 occurs in the input
All of these
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2. With increasing demand in variety, the management decides to produce 1800 different kinds
of products with the same machine. A unique input should specify the production of each of
the products, apart from two different