ISRO Computer Science (CSE) 2014 Question Paper & Solutions

Question 1

Consider a 33 MHz CPU based system. What is the number of wait states required if it is interfaced with a 60 ns memory? Assume a maximum of 10 ns delay for additional circuitry like buffering and decoding.

Accepted Answer

2

Answer

0

Answer

1

Answer

3

Question 2

The number of states required by a Finite State Machine, to simulate the behavior of a computer with a memory capable of storing 'm' words, with each being 'n' bits long is

Accepted Answer

$2^{mn}$

Answer

$m 	imes 2^n$

Answer

$2^{m+n}$

Answer

$m+n$

Question 3

What is the output of the following C program?
```c
#include <stdio.h>
#define SQR(x) (x*x)
int main ()
{ 
 int a, b = 3;
 a = SQR (b + 2);
 printf("%d
", a);
 return 0;
}
```

Accepted Answer

11

Answer

25

Answer

15

Answer

None of the above

Question 4

Consider the following pseudocode:
```
while (m < n)
 if (x > y) and (a < b) then
 a = a + 1
 y = y - 1
 end if
 m = m + 1
end while
```
What is cyclomatic complexity of the above pseudocode?

Accepted Answer

4

Answer

2

Answer

3

Answer

5

Question 5

What is the number of steps required to derive the string `((() ()) (()))` for the following grammar?
$S ightarrow SS$
$S ightarrow (S)$
$S ightarrow \varepsilon$

Accepted Answer

10

Answer

12

Answer

16

Answer

15

Question 6

The process of modifying IP address information in IP packet headers while in transit across a traffic routing device is called

Accepted Answer

Network address translation (NAT)

Answer

Port address translation (PAT)

Answer

Address mapping

Answer

Port mapping

Question 7

What does a pixel mask mean?

Accepted Answer

string containing 1's and 0's

Answer

string containing only 1's

Answer

string containing only 0's

Answer

string containing two 0's

Question 8

In the standard IEEE 754 single precision floating point representation, there is 1 bit for sign, 23 bits for fraction and 8 bits for exponent. What is the precision in terms of the number of decimal digits?

Accepted Answer

7

Answer

5

Answer

6

Answer

8

Question 9

Let $R$ be the radius of the circle. What is the angle subtended by an arc of length $R$ at the center of the circle?

Accepted Answer

1 radian

Answer

1 degree

Answer

90 degrees

Answer

$\pi$ radians

Question 10

The number of logical CPUs in a computer having two physical quad-core chips with hyper threading enabled is ________.

Accepted Answer

16

Answer

1

Answer

2

Answer

8

Question 11

An aggregation association is drawn using which symbol?

Accepted Answer

A small open diamond at the end of a line connecting two tables

Answer

A line which loops back on to the same table

Answer

A small closed diamond at the end of a line connecting two tables

Answer

A small closed triangle at the end of a line connecting two tables

Question 12

How many states are there in a minimum state deterministic finite automaton accepting the language $L = \{w \mid w \in \{0, 1\}^*, 	ext{number of 0's is divisible by 2 and number of 1's is divisible by 5} \}$?

Accepted Answer

10

Answer

7

Answer

9

Answer

11

Question 13

Which of the following is true with respect to reference?

Accepted Answer

A reference can never be NULL

Answer

A reference needs an explicit dereferencing mechanism

Answer

A reference can be reassigned after it is established

Answer

A reference and pointer are synonymous

Question 14

There are 200 tracks on a disc platter and the pending requests have come in the order: 36, 69, 167, 76, 42, 51, 126, 12 and 199. Assume the arm is located at the $100^{th}$ track and moving towards track 200. If sequence of disc access is 126, 167, 199, 12, 36, 42, 51, 69 and 76 then which disc access scheduling policy is used?

Accepted Answer

C-SCAN

Answer

Elevator

Answer

Shortest seek-time first

Answer

First Come First Served

Question 15

Consider the logic circuit given below. What is $Q = ?$ 
[Circuit Diagram: Top NAND inputs D, C. Middle NAND inputs B, Output of Top. Bottom NAND inputs A, Output of Middle. Output Q is from Bottom NAND.]

Accepted Answer

$A\overline{B} + A\overline{C} + \overline{C}D$

Answer

$\overline{A}C + \overline{B}\overline{C} + CD$

Answer

$ABC + \overline{C}D$

Answer

$AB + \overline{B}C + B\overline{D}$

Question 16

What is routing algorithm used by OSPF protocol?

Accepted Answer

Link state

Answer

Distance vector

Answer

Flooding

Answer

Path vector

Question 17

If each address space represents one byte of storage space, how many address lines are needed to access RAM chips arranged in a $4 	imes 6$ array, where each chip is $8	ext{ K} 	imes 4$ bits?

Accepted Answer

17

Answer

13

Answer

15

Answer

16

Question 18

Consider the following segment table in segmentation scheme:
| Segment Id | Base | Limit |
|---|---|---|
| 0 | 200 | 200 |
| 1 | 5000 | 1210 |
| 2 | 1527 | 498 |
| 3 | 2500 | 50 |
What happens if the logical address requested is segment ID 2 and offset 1000?

Accepted Answer

A trap is generated

Answer

Fetches the entry at the physical address 2527 for segment Id 2

Answer

Deadlock

Answer

Fetches the entry at offset 27 in segment Id 3

Question 19

The number of bit strings of length 8 that will either start with 1 or end with 00 is?

Accepted Answer

160

Answer

32

Answer

128

Answer

192

Question 20

Which of the following is not a maturity level as per Capability Maturity Model?

Accepted Answer

Measurable

Answer

Initial

Answer

Repeatable

Answer

Optimized

Question 21

What are the final values of $Q_1$ and $Q_0$ after 4 clock cycles, if initial values are 00 in the sequential circuit shown below?
[Circuit: T flip-flop Q0 clocked by CLK, T input is 1. T flip-flop Q1 clocked by Q0 output? No, arrow from Q0 to Clock of Q1. T input of Q1 is 1.]

Accepted Answer

00

Answer

11

Answer

01

Answer

10

Question 22

Consider the schema $R(A, B, C, D)$ and the functional dependencies $A 	o B$ and $C 	o D$. If the decomposition is made as $R_1(A, B)$ and $R_2(C, D)$, then which of the following is TRUE?

Accepted Answer

Preserves dependency but cannot performs lossless join

Answer

Preserves dependency and performs lossless join

Answer

Does not preserve dependency and cannot performs lossless join

Answer

Does not preserve dependency but performs lossless join

Question 23

The test suite (set of test input) used to perform unit testing on a module could cover 70% of the code. What is the reliability of the module if the probability of success is 0.95 during above testing?

Accepted Answer

At the most 0.665

Answer

0.665 to 0.95

Answer

At the most 0.95

Answer

At least 0.665

Question 24

In a system an RSA algorithm with $p = 5$ and $q = 11$, is implemented for data security. What is the value of the decryption key if the value of the encryption key is 27?

Accepted Answer

3

Answer

7

Answer

27

Answer

40

Question 25

Suppose you want to build a memory with 4 byte words and a capacity of $2^{21}$ bits. What is type of decoder required if the memory is built using $2	ext{ K} 	imes 8$ RAM chips?

Accepted Answer

5 to 32

Answer

6 to 64

Answer

4 to 16

Answer

7 to 128

Question 26

The output of a tristate buffer when the enable input is 0 is

Accepted Answer

Disconnected state

Answer

Always 0

Answer

Always 1

Answer

Retains the last value when enable input was high

Question 27

How many different BCD numbers can be stored in 12 switches? (Assume two position or on-off switches)

Accepted Answer

$10^3$

Answer

$2^{12}$

Answer

$2^{12} - 1$

Answer

$10^{12}$

Question 28

Suppose there are 11 items in sorted order in an array. How many searches are required on the average, if binary search is employed and all searches are successful in finding the item?

Accepted Answer

3.00

Answer

3.46

Answer

2.81

Answer

3.33

Question 29

Consider the following Java code fragment.
```java
1. Public class while 
2. { 
3. Public void loop() 
4. { 
5. int x = 0; 
6. while(1) 
7. { 
8. system.out.println("x plus one is" + (x + 1)); 
9. } 
10. } 
11. }
```
Which of the following statements is true?

Accepted Answer

There is syntax error in line no. 1 and 6

Answer

There is syntax error in line no. 1

Answer

There is syntax error in line no. 8

Answer

There is syntax error in line no. 6

Question 30

Every time the attribute $A$ appears, it is matched with the same value of attribute $B$ but not the same value of attribute $C$. Which of the following is true?

Accepted Answer

$A 	o B, A 	o	o C$

Answer

$A 	o (B, C)$

Answer

$A 	o B, C 	o	o A$

Answer

$A 	o	o B, B 	o C$

Question 31

A IP packet has arrived in which the fragmentation offset value is 100, the value of HLEN is 5 and the value of total length field is 200. What is the number of the last byte?

Accepted Answer

979

Answer

194

Answer

394

Answer

1179

Question 32

What is the output of the following C program? ```c # include void main (void) { int shifty; shifty = 0570; shifty = shifty >> 4; shifty = shifty << 6; printf("The value of shifty is %o", shifty); } ```

Accepted Answer

The value of shifty is 2700

Answer

The value of shifty is 15 00

Answer

The value of shifty is 4300

Answer

The value of shifty is 5700

Question 33

The following Finite Automation recognizes which of the given languages?
[Diagram: q0 (start) -> 0 -> q0, q0 -> 1 -> q1. q1 -> 0 -> q2 (final), q1 -> 1 -> q1. q2 -> 0 -> q2, q2 -> 1 -> q1.]

Accepted Answer

$(1, 0)^*[01]$

Answer

$(1, 0)^*[1]*[1]$

Answer

$\{1\}\{1, 0\}^*\{1\}$

Answer

$1^*0^*(0, 1)$

Question 34

How much memory is required to implement z-buffer algorithm for a $512 	imes 512 	imes 24$ bit-plane image?

Accepted Answer

1 MB

Answer

768 KB

Answer

1.5 MB

Answer

2 MB

Question 35

Using the page table shown below, translate the physical address 25 to virtual address. The address length is 16 bits and the page size is 2048 words while the size of physical memory is four frames.
[Table: Page 0->3, Page 1->2, Page 2->0, Page 3->-]
[Wait, question asks Physical 25 to Virtual? Or Logical 25 to Physical? "translate the physical address 25 to virtual address".]
[Usually we translate Virtual to Physical. If physical is 25, we need to find which frame contains 25. Frame size = 2048.]

Accepted Answer

4121

Answer

25

Answer

6169

Answer

2073

Question 36

Consider a standard Circular queue implementation (which has the same condition for queue full and queue empty) whose size is 11 and the elements of the queue are $q[0], q[1], ..., q[10]$. The front and rear pointers are initialized to point at $q[2]$. In which position will the ninth element be added?

Accepted Answer

$q[10]$

Answer

$q[0]$

Answer

$q[1]$

Answer

$q[9]$

Question 37

The probability that two friends are born in the same month is ________?

Accepted Answer

1/12

Answer

1/6

Answer

1/144

Answer

1/24

Question 38

How many lines of output does the following C code produce?
```c
#include <stdio.h>
float i = 2.0;
float j = 1.0; 
float sum = 0.0;
main()
{ 
 while (i/j > 0.001) 
 {
 j = j + j;
 sum = sum + (i/j);
 printf("%f
", sum);
 }
}
```

Accepted Answer

11

Answer

8

Answer

9

Answer

10

Question 39

If only one memory location is to be reserved for a class variable, no matter how many objects are instantiated, then the variable should be declared as

Accepted Answer

static

Answer

extern

Answer

volatile

Answer

const

Question 40

Assume that 16-bit CPU is trying to access a double word starting at an odd address. How many memory operations are required to access the data?

Accepted Answer

3

Answer

1

Answer

2

Answer

4

Question 41

Consider the following binary search tree T given below. Which node contains the fourth smallest element in T?
[Diagram: P -> L:Q, R:V. Q -> L:U, R:W. U -> R:X? V -> R:Y. W -> L:X?, R:Z. Diagram is P(Q(U, W(X, Z)), V(Y?)). The arrows are a bit distinct.]
Tree structure from visual: Root P. Left Q. Right V.
Q has Left U, Right W.
U has no children?
W has Left X, Right Z.
V has Left ?, Right Y.
In-order traversal (Sorted): 
Subtree Q: U, Q, X, W, Z. 
Then P.
Then Subtree V.
Order: U, Q, X, W, Z, P, ...
1st: U. 2nd: Q. 3rd: X. 4th: W.

Accepted Answer

W

Answer

Q

Answer

V

Answer

X

Question 42

Let $x, y, z, a, b, c$ be the attributes of an entity set E. If $\{x\}, \{x, y\}, \{a, b\}, \{a, b, c\}, \{x, y, z\}$ are superkeys then which of the following are the candidate keys?

Accepted Answer

$\{x\}$ and $\{a, b\}$

Answer

$\{x, y\}$ and $\{a, b\}$

Answer

$\{x, y, z\}$ and $\{a, b, c\}$

Answer

$\{z\}$ and $\{c\}$

Question 43

The five items: A, B, C, D, and E are pushed in a stack, one after other starting from A. The stack is popped four times and each element is inserted in a queue. Then two elements are deleted from the queue and pushed back on the stack. Now one item is popped from the stack. The popped item is

Accepted Answer

D

Answer

A

Answer

B

Answer

C

Question 44

A computer has 16 pages of virtual address space but the size of main memory is only four frames. Initially the memory is empty. A program references the virtual pages in the order of 0, 2, 4, 5, 2, 4, 3, 11, 2, 10. How many page faults occur if LRU page replacement algorithm is used?

Accepted Answer

8

Answer

3

Answer

5

Answer

7

Question 45

Consider a 50 Kbps satellite channel with a 500 milliseconds round trip propagation delay. If the sender wants to transmit 1000 bit frames, how much time will it take for the receiver to receive the frame?

Accepted Answer

270 ms

Answer

250 ms

Answer

20 ms

Answer

520 ms

Question 46

If the maximum output voltage of a DAC is V volts and if the resolution is R bits then the weight of the most significant bit is

Accepted Answer

$\frac{V(2^{R-1})}{2^R - 1}$

Answer

$\frac{V}{2^R - 1}$

Answer

$(2^{R-1}) \cdot V$

Answer

$\frac{V}{(2^R - 1)}$

Question 47

The following three 'C' language statements is equivalent to which single statements?
```c
y = y + 1;
z = x + y;
x = x + 1;
```

Accepted Answer

z = (x++) + (++y);

Answer

z = x + y + 2;

Answer

z = (++x) + (y++);

Answer

z = (x++) + (++y) + 1;

Question 48

A frame buffer array is addressed in row major order for a monitor with pixel locations starting from (0, 0) and ending with (100, 100). What is address of the pixel (6, 10)? Assume one bit storage per pixel and starting pixel location is at 0.

Accepted Answer

616

Answer

1016

Answer

1006

Answer

610

Question 49

Consider a single linked list where F and L are pointers to the first and last elements respectively of the linked list. The time for performing which of the given operations depends on the length of the linked lists?

Accepted Answer

Delete the last element of the list

Answer

Delete the first element of the list

Answer

Interchange the first two elements of the list

Answer

Add an element at the end of the list

Question 50

Let A be a finite set having $x$ elements and let B be a finite set having $y$ elements. What is the number of distinct functions mapping B into A.

Accepted Answer

$x^y$

Answer

$2^{(x+y)}$

Answer

$y^x$

Answer

$\frac{y!}{(y-x)!}$

Question 51

Which of the following is NOT represented in a subroutine's activation record frame for a stack-based programming language?

Accepted Answer

Heap area

Answer

Values of local variables

Answer

Return address

Answer

Information needed to access non local variables

Question 52

Consider the following grammar:
$S 	o AB$
$A 	o a$
$A 	o BaB$
$B 	o bbA$
Which of the following statements is FALSE?

Accepted Answer

No string produced by this grammar has four consecutive b's

Answer

The length of every string produced by this grammar is even

Answer

No string produced by this grammar has three consecutive a's

Answer

The length of substring produced by B is always odd

Question 53

Consider the logic circuit given below. [Inverter (6ns) -> AND (10ns) -> OR (11ns). Inputs A, B, C. A feeds Inverter and AND. B feeds AND. Inverter feeds OR. C feeds OR. Q is output.] 
The inverter, AND and OR gates have delays of 6, 10 and 11 nanoseconds respectively. Assuming that wire delays are negligible, what is the duration of glitch for Q before it becomes stable?

Accepted Answer

5

Answer

16

Answer

27

Answer

None

Question 54

The conic section that is obtained when a right circular cone is cut through a plane that is parallel to the side of the cone is called

Accepted Answer

parabola

Answer

hyperbola

Answer

circle

Answer

ellipse

Question 55

An IP packet has arrived with the first 8 bits as 0100 0010. Which of the following is correct?

Accepted Answer

The receiver rejects the packet

Answer

The number of hops this packet can travel is 2.

Answer

The total number of bytes in header is 16 bytes

Answer

The upper layer protocol is ICMP

Question 56

Which of the following is not valid Boolean algebra rule?

Accepted Answer

$\overline{X} + XY = Y$

Answer

$X \cdot X = X$

Answer

$(X + Y) \cdot X = X$

Answer

$(X + Y) \cdot (X + Z) = X + YZ$

Question 57

A supernet has a first address of 205.16.32.0 and a supernet mask of 255.255.248.0. A router receives 4 packets with the following destination addresses. Which packet belongs to this supernet?

Accepted Answer

205.16.39.44

Answer

205.16.42.56

Answer

205.17.32.76

Answer

205.16.31.10

Question 58

Assume the following information:
Original timestamp value = 46
Receive timestamp value = 59
Transmit timestamp value = 60
Timestamp at arrival of packet = 69
Which of the following statements is correct?

Accepted Answer

Receive clock should go back by 3 milliseconds

Answer

Transmit and receive clocks are synchronized

Answer

Transmit clock should go back by 3 milliseconds

Answer

Receive clock should go ahead by 1 millisecond

Question 59

Which of the following is FALSE with respect to possible outcomes of executing a Turning Machine over a given input?

Accepted Answer

it may halt by changing the input

Answer

it may halt and accept the input

Answer

it may halt and reject the input

Answer

it may never halt

Question 60

Suppose you are browsing the world wide web using a web browser and trying to access the web servers. What is the underlying protocol and port number that are being used?

Accepted Answer

TCP, 80

Answer

UDP, 80

Answer

TCP, 25

Answer

UDP, 25

Question 61

A mechanism or technology used in Ethernet by which two connected devices choose common transmission parameters such as speed, duplex mode and flow control is called

Accepted Answer

Auto negotiation

Answer

Autosense

Answer

Synchronization

Answer

Pinging

Question 62

Consider the following sorting algorithms.
1. Quicksort
2. Heapsort
3. Mergesort
Which of them perform in least time in the worst case?

Accepted Answer

2 and 3 only

Answer

1 and 2 only

Answer

3 only

Answer

1, 2 and 3

Question 63

Consider the following table:
[Diagram: A -> B, B -> C, C -> D, D -> E. Dependency chain]
The table is in which normal form?

Accepted Answer

Third Normal Form but not BCNF

Answer

First Normal Form

Answer

Second Normal Form

Answer

Third Normal Form and BCNF

Question 64

Consider a 13 element hash table for which $f(key) = key \pmod{13}$ is used with integer keys. Assuming linear probing is used for collision resolution, at which location would the key 103 be inserted, if the keys 661, 182, 24 and 103 are inserted in that order?

Accepted Answer

1

Answer

0

Answer

11

Answer

12

ISRO Computer Science (CSE) 2014 Question Paper & Solutions

Question 1

Question 2

Question 3

Question 4

Question 5

Question 6

Question 7

Question 8

Question 9

Question 10

Question 11

Question 12

Question 13

Question 14

Question 15

Question 16

Question 17

Question 18

Question 19

Question 20

Question 21

Question 22

Question 23

Question 24

Question 25

Question 26

Question 27

Question 28

Question 29

Question 30

Question 31

Question 32

Question 33

Question 34

Question 35

Question 36

Question 37

Question 38

Question 39

Question 40

Question 41

Question 42

Question 43

Question 44

Question 45

Question 46

Question 47

Question 48

Question 49

Question 50

Question 51

Question 52

Question 53

Question 54

Question 55

Question 56

Question 57

Question 58

Question 59

Question 60

Question 61

Question 62

Question 63

Question 64

Question 65

Question 66

Question 67

Question 68

Question 69

Question 70

Question 71

Question 72

Question 73

Question 74

Question 75

Question 76

Question 77

Question 78

Question 79