ISRO CS 2007

Question 1

The Boolean expression Y = (A + B' + A'B)C' is given by

• A. AC'
• B. BC'
• C. C'
• D. AB

Answer: (C)

ISRO CS 2007 Digital Logic & Number representation Logic functions and Minimization
Discuss it

Y = (A + B' + A'B)C'
Y = AC' + B'C' + A'BC'
Y = (A + A'B)C' + B'C'
Y = (A + B)C' + B'C'
Y = AC' + BC' + B'C'
Y = AC' + C'(B + B') // B + B' = 1
Y = AC' + C'
Y = C'

So, option (C) is correct.

Question 2

The circuit shown in the following figure realizes the function

• A. (( A + B )' +C ) ( D'E' )
• B. (( A + B )' + C ) ( DE' )
• C. ( A + ( B + C )' ) ( D'E )
• D. ( A + B + C' ) ( D'E' )

Answer: (A)

ISRO CS 2007 Digital Logic & Number representation Logic functions and Minimization
Discuss it

The given function is equivalent to the following expression:

Y = (((A + B)' + C)' + ((D + E)')')'
Y = ((A + B)' + C)')' . (D + E)'
Y = ((A + B)' + C) (D'E')

Option (A) is correct.

Question 3

The circuit shown in the given figure is a

• A. full adder
• B. full subtracter
• C. shift register
• D. decade counter

Answer: (B)

ISRO CS 2007 Digital Logic & Number representation Combinational Circuits
Discuss it

The circuit shown in the given figure is a full subtractor. Refer: Digital Logic | Full Subtractor Option (B) is correct.

Question 4

When two numbers are added in excess-3 code and the sum is less than 9, then in order to get the correct answer it is necessary to

• A. subtract 0011 from the sum
• B. add 0011 to the sum
• C. subtract 0110 from the sum
• D. add 0110 to the sum

Answer: (A)

ISRO CS 2007 Digital Logic & Number representation Combinational Circuits
Discuss it

Question 5

The characteristic equation of an SR flip-flop is given by

• A. Q_n+1 = S + RQ_n
• B. Q_n+1= RQ'_n + SQ_n
• C. Q_n+1= S' + RQ_n
• D. Q_n+1 = S + R'Q_n

Answer: (D)

ISRO CS 2007 Digital Logic & Number representation Sequential circuits
Discuss it

The characteristic table of an SR flip-flop is: So, by simplifying using k-maps: characteristic equation of an SR flip-flop = Q_n+1 = S + R'Q_n Option(D) is correct.

Question 6

A graph with n vertices and n-1 edges that is not a tree, is

• A. Connected
• B. Disconnected
• C. Euler
• D. A circuit

Answer: (B)

ISRO CS 2007 Top MCQs on Graph Theory in Mathematics
Discuss it

If a graph has n vertices and n-1 edges and it is not a tree than its a disconnected graph which contains at least a cycle. Option (B) is correct.

Question 7

If a graph requires k different colours for its proper colouring, then the chromatic number of the graph is

• A. 1
• B. k
• C. k-1
• D. k/2

Answer: (B)

ISRO CS 2007 Top MCQs on Graph Theory in Mathematics
Discuss it

The chromatic number of a graph is the smallest number of colors needed to color the vertices of so that no two adjacent vertices share the same color and if a graph requires k different colours for its proper colouring, then k is the chromatic number of the graph.

Question 8

A read bit can be read

• A. and written by CPU
• B. and written by peripheral
• C. by peripheral and written by CPU
• D. by CPU and written by the peripheral

Answer: (D)

ISRO CS 2007 OS Input Output Systems
Discuss it

The read and write functionality depends on the type of microcontroller peripheral. Generally, the status bits have a read only status and can be modified by peripherals only. So, read bit can be read by CPU and written by the peripheral. Option (D) is correct.

Question 9

A read bit can be read

• A. and written by CPU
• B. and written by peripheral
• C. by peripheral and written by CPU
• D. by CPU and written by the peripheral

Answer: (D)

ISRO CS 2007
Discuss it

Question 10

The term ‘aging’ refers to

• A. booting up the priority of the process in multi-level of queue without feedback.
• B. keeping track of the following a page has been in memory for the purpose of LRU replacement
• C. letting job reside in memory for a certain amount of time so that the number of pages required can be estimated accurately.
• D. gradually increasing the priority of jobs that wait in the system for a long time to remedy infinite blocking

Answer: (D)

ISRO CS 2007 OS Memory Management
Discuss it

In Operating systems, aging is a scheduling technique used to avoid starvation. In this, the priority of the jobs that have a longer waiting time is increased as compared to the newer processes, to avoid the starvation of older processes. Option (D) is correct.