# ISRO 2008 COMPUTER SCIENCE SOLVED

1.Which of the following is an illegal array definition?                                                        a) type COLOGNE: (LIME,PINE,MUSK,MENTHOL);var a:array [COLOGNE]of REAL;

b)var a:array[REAL]of REAL;

c)var a:array[‘A’..’Z]of REAL;                                                                                            d) var a:array[BOOLEAN] of REAL;

2.The term Phong associated to with

a)Race tracing

c)hiddenline removal

d)a game

1. a) extends the network portion to 16 bits
2. b) extends the network portion to 26 bits
3. c) extends the network portion to 36 bits

d)has no effect on the network portion of an IP addresss

4.On a LAN,where are where are IP datagrams transported?

(b) IN the application field

(c) In the  information field of LAN  frame

(d )  After the TCP header.

1. In the Ethernet , the source address field in the MAC frame is the___ addresss.

(a)Original sender’s physical

(b) previous station  physical

(c ) next destination physical.

(d)original sender’s service port.

6.which is the following transmition media  is not readily suitable to CSMA operation?

(B)optical fiber

(C) coaxial cable

(D)twisted pair

7.Consider the grammer

SàABCc|bc

BAà AB

Bbàbb

Abàab

Aaàaa

Which is the following sentence  can be derived by this grammer?

(a)abc                                (b)aab

(c)abcc                               (d)abbc

8.The TCP sliding window

(a)can be used to control the flow of information

(b)always occur when the field value is 0

(c) )always occur when the field value is 1

(d)occur horizontally.

9.What is the bandwidth of a signal that ranges from 40kHz to 4 MHz?

a)36 MHz

b)360 kHz

c)3.96 MHz

d)396 kHz

10Which Project 802 standard provides for a collision –free protocol?

a)802.2

b)802.3

c)802.5

d)802.6

14.Assume that each character code consists of 8 bits .The number of characters that can be transmitted per second through  an synchronous serial line at 2400 baud rate ,and  with two stop bit is

a)109

b)216

c)218

d)219

1. Four jobs to be executed on a single processor system arrive at time 0 in the order A,B,C,D  .There CPU burst time requirements 4,1,8,1, time units repectively.The completion time of A under round robin scheduling with time slice of one time  unit is

a)10

b)4

c)8

d)9

16.Which one of the following algorithm design techniques is used in finding all pairs of shortest distances in a graph ?

a)dynamic programming

b)backtracking

c)greedy

d)divide and conquer

17.The address space of 8086 CPU is

a)one Megabyte

b)256 kilobytes

c)1 K Megabytes

d)64 kilobytes

18.More than one word are put in one cache block to

a)exploit the temporal locality of refrence in a program

1. b) exploit the spatial  locality of refrence in a program

c)reduce the miss penalty

d)none of these

19.The performance of a pipelined processor suffers if

a)the pipeline stages have different delay

b)consecutive instructions are dependent on each other

c)the pipeline stages share hardware resources

d)all of these

1. The advantage of MOS devices over bipolar devices is that

a)it allows higher bit densities and also cost effective

b)it is easy to fabricate

c)its higher –impedance and operational speed

d)all of thse

23.A computer  uses 8 digit mantissa and 2 digit exponent  .If a =0.052 and b=28E+11,the b+a-b will

a)result in an overflow error

b)result in an underflow error

c)be 0

d)be 5.28E+11

28.Which of the following is  not a valid rule for XOR?

a)0 XOR 0=0

1. b) 1 XOR 1=1
2. c) 1 XOR 0=1

d)B XOR  B=0

29.The number of distinct simple graphs with up to three nodes is

a)15

b)10

c)7

d)9

32.The network 198.78.41.0 is a

a)class A network

b)class B network

1. c) class C network
2. d) class D network

33.The join operation can be defined as

1. a) a Cartesian product of two relations followed by a selection

b)a Cartesian product of two relations

c)a union of two relations followed by Cartesian product of the two relations

d)a union of two relations

35.Embedded pointer provides

a)an inverted index

b)a secondary access path

c)a physical recorded key

d)a primary key

36.An interrupt in which the external device supplies its address as well as the interrupt requests is known as

a)vectoed interrupt

d)designated interrupt

37.The ability to temporarily halt the CPU and use this time to send information bues is called

a)direct memory access

b)vectoring the interrupt

c)polling

d)cycle stealing

38.Relative to the program translated by the compiler ,the same program when interpreted runs

a)faster

b)slower

c)at the same speed

d)may be faster or slower

39.Consider the following assembly language program

MVIA        30H

ACI              30H

XRA             A

POP              H

After the execution of the  above program, the contents of the accumulator will be

a)30H

b)60H

c)00 H

d)contents of stack

41.In a resident-OS computer,which of the followi ng systems must reside in the main memory under all the situations?

1. a) assembler

d)compiler

42.Which of the following architechture is/are  not suitable for realizing SIMD?

a)vector processor

b)array processor

c)Von Neumann

d)All of the above

44.The device which is used to connect to a peripheral to bus is known as

a)control register

b)interface

c)communication protocol

d)none of these

45.The  TRAP is one of the interrupts available in INTEL 8085.Which one of the following statement is true of TRAP?

a)it is level  triggered

b)it is negative edge triggered

c)it is +ve edge triggered

d)it is both +ve and –ve edge triggered

46.Raid configurations of disks are used to provide

a)fault-tolerance

b)high speed

c)high data density

d)none of these

47.Which of the following need not necessarily be saved on a context switch between processes?

a)general purpose registers

b)translation lookaside buffer

c)program counter

d)all  of these

48.Which of the following is termed as minimum error code?

a)binary code

b)gray code

c)excess 3 code

d)octal code

49.The total time to prepare a disk drive mechanism for a block of data to be read from it is

a)seek time

b)latency

c)latency plus seek time

d)transmission time

50.Feedback queues

a)are very simple to implement

b)dispatch tasks according to execution characteristics

c)are used to favor real time tasks

d)require manual intervention to implement properly

51.With Round-Robin CPU scheduliung in a time shared system

a)using very large time slices (quantas) degenerates into First-come-first –served (FCFS) algorithm

b)using extremely small time slices improves performance

1. c) using very small time slices degenerates into Last-In-First –Out(LIFO) algorithm

d)using medium sized time slices lead to shortest request time first (SRTF) algorithm

a)is part of operating system paging algorithm

b)is useless when swapping is used

c)is the hardware necessary to implement paging

d)storage pages at the specific location on disk

53.Thrashing

a)always occur on large computer

b)is a natural consequence of virtual memory systems

c)can always be avoided by swapping

d)can be caused by poor paging algorithms

54.What is the name of operating system that reads and reacts in term of actual time ?

a)Batch system

b)quick response system

c)real time system

d)time sharing system

a)is a hardware memory device which denotes the location of the current instruction being executed

b)is a group of electrical ckt,that performs the intent of instruction fetched from memory

c)contains the address of memory location that is to be read from  or stored into

d)contains the copy of the designated memory location specified by the MAR after “read “ or the new contents of memory prior to a “write”

56.An examole of spooled device is a

a)line printer used to print the  output of number of jobs

b)terminal used to enter input data to a running program

c)secondary storage device in a virtual memory system

d)graphic display device

57.Dirty  bit for a page in a page table

a)helps avoid unnecessary writes on paging  device

b)helps maintain LRU information

c)allows only read on  a page

d)none of these

58.Checkpointing a job is

a)allows it to be completely successfully

b)allows it to continuing executing later

c)prepares it  for finishing

d)occurs only when there is an error in it

59.Apublic key encryption system

a)allows anyone to decode the transmissions

b)allows only the correct sender to decode the data

1. c) allows only the correct receiver  to decode the data
2. d) does not encode the data before transmitting it

60.Overlaying

1. b) allows large programs,but require more effort

c)is most used on large computer

1. d) is transparent to the user

61.A critical section ia s program segment

a)which should run in a certain specified amount of time

c)where shared resources are accessed

d)which must be endorsed by a pair of semaphore operations P,U

62.In which of the following four necessary  conditions for deadlock processes claim exclusive control of the resources they acquire  ?

a)no preemption

b)mutual exclusion

c)citcular wait

d)hold and wait

63.Fork is

a)the creation of a new job

c)increasing the priority of a task

d)the creation of a new process

64.Which of the following need not necessarily br saved on a context switch between processes?

a)general purpose register

b)translation look aside buffer

c)program counter

d)stack pointer

65.Consider a logical address space of 8 pages of.1024 words mapped into memory of 32 frames .How many bits are there in the logical address ?                                     a) 13 bits

b)15 bits

c)14 bits

d)12 bits

Logical address space=No of page *Page offset

=8*1024W

=2^13 words

So 13 bits are there in the logical address

66.The performance of Round robin algorithm depends heavily on                               a) size of the process

b)the I/O burst of the process

c)the CPU burst of the process

d)the size of the time quantum

The performance of Round Robin algorithm depends heavily on the size of the time quantum.

If time quantum is too large, RR reduces to the FCFS algorithm

If time quantum is too small, overhead increases due to amount of context switching needed.

67.The page replacement algorithm which gives the lowest page default rate is

a)LRU

b)FIFO

c)optional page replacement                                                                                            d) second chance algorithm

68.Which of the following class of statement usually produces no executable code

When compiled?

a)declaration

b)assignment statements

c)input and output statements

d)structural statements

69. What is the value of F(4) using the following procedure:

function F(K : integer)
integer;
begin
if (k<3) then F:=k else F:=F(k-1)*F(k-2)+F(k-3)
end;
1. 5
2. 6
3. 7
4. 8

Here f(1)=1

f(2)=2

f(4) = f(3)*f(2)+f(1)

f(3)=f(2)*f(1)+f(0) =2*1+0=2

f(4)=2*2+1=5

70.  Stack A has the entries a, b, c(with a on top).Stack B is empty .A entry popped out of stack A can be printed immediately or pushed to stack B . An entry popped out of the stack B can only be printed. In this arrangement ,which of the following permutations of a, b, c are not possible ?                                                                        a) b a c

b)b c a

c)c a b

d)a b c

71. The time required to search an element in a linked list of length n is

1. O(log2n)
2. O(n)
3. O(1)
4. O(n2)

1. Which of the following operations is performed more efficiently by doubly linked list than by linear linked list ?

a)deleting a node whose location is given

b)searching an unsorted list or a given item

c)inserting a node after the node with a given location

d)traversing the list  to process each node.

In this question, we can simply eliminate the (2) and (4) from our choice, since in both the cases we need to visit every node one after other. Doubly LL will serve no extra good in these two cases as we need to proceed from starting node and go until the last note in LL or vice-versa .

(2)  To insert a new node in the LL after some specific node, we need not go back to the previous node in the LL. And thus, doubly LL will serve no purpose in this case too.

At last, in the case of (1) we are supposed to delete the node (say x) whose location is given. Which means that before we remove node x from the LL we need to store the address of next node in the list, linked to node x in the address field of node just before node x (which currently store the address of node x). Since we need to go back-and-forth in the list during this operation, doubly linked list will be a good help in increasing the efficiency by decreasing the time required for the operation.

73.We can make a class abstract by

a)declaring it abstract using the virtual keyboard

b)making at least one member function as virtual function                                              c) making at least one member function as pure virtual function                                     d) making all member function as const.

A pure virtual function or abstract function in C++ is a virtual function for which we don’t have any implementation, we can only declare it.

A pure virtual function is implemented by classes which are derived from a abstract class.

74.A Steiner patch is                                                                                                               a) Biquadratic Beizer patch

b)Bicubic patch                                                                                                                     c) circular patch only

d)bilinear beizer patch

75.A complete binary tree with the property that value each node is at least as large as the value as its children known as

a)binary search tree

b)AVL tree

c)completely binary trees

d)Heap

Heap or (max heap) which is a complete binary tree with every node has value more than or equal to  its children

76.The minimum number of fields with each node of doubly linked list is                             a) 1                    b) 2                      c) 3                  d) 4

77. How many comparisons are needed to sort an array of length 5 if a straight selection sort is used an array is already in the opposite order

a)1

b)10

c)15

d)20

whatever order they are arranged the number of comparisons will be sum of n-1 terms.
Here n=5
So total comparisons= 4*(4+1)/2=10.

78 Consider the graph shown in the figure below:

Which of the following is a valid strong component?

a, c, d

a, b, d

b, c, d

a, b, c

A directed graph is strongly connected if there is a path between all pairs of vertices.

So given graph has a b c as a strong component.

79.Repeated execution of simple computation may cause compounding of

a)round-off errors

b)syntax errors

c)run-time error

d)logic errors

Roundoff error is the difference between an approximation of a number used in computation and its exact (correct) value. In certain types of computation, roundoff error can be magnified as any initial errors are carried through one or more intermediate steps.

80.In C,what is the effect of a negative number in a field width specifier?

a)the values are  displayed  right specifier                                                                        b) the values are displayed centered                                                                                  c) the values are displayed left specifier                                                                            d) the values are displayed as negative numbers

The effect of a negative number in a field  Width specifier the values are displayed left justified.