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Nta ugc net Nov 2020 paper II question and solution computer science part-2

 

Q1 Consider a hypothetical machine with 3 pages of physical memory ,5 pages of virtual memory and <A,B,C,D,A,B,E,A,B,C,D,E,B,A,B> as the stream of page references by an application. If  P and Q  are the number of page faults that the application would incur with FIFO and LRU page replacement  algorithm respectively then (P,Q) is

(1) (11,10)

(2) (12,11)

(3) (10,11)

(4) (11,12)

Solution (4)

FIFO

ABC   (3 page fault)

BCD  insert D remove A   (1 page fault)

CDA  insert A remove B(1 page fault)

DAB insert B remove C (1 page fault)

ABE insert E remove D(1 page fault)

A,B no page fault already in memory.

BEC remove A insert C ( 1 page fault)

ECD remove B insert D(1 page fault)

E no page fault already in memory.

CDB remove E insert B(1 page fault)

DBA remove C insert  A (1 page fault)

B no page fault already in memory.

In FIFO total page fault=3+1+1+1+1+1+1+1+1=11

LRU

ABC (3 page fault)

BCD remove A Insert D(1 page fault)

CDA remove B Insert A(1 page fault)

DAB remove C Insert B(1 page fault)

ABE remove D insert E(1 page fault)

A B already in memory so no page fault 

EAB

ABC remove E Insert C(1 page fault)

BCD remove A insert D (1 page  fault)

CDE remove B insert E(1 page fault)

DEB remove C insert B(1 page fault)

EBA remove D insert A (1 page fault)

B no page fault already in memory.

Total page fault in LRU=3+1+1+1+1+1+1+1+1+1=12

Q2 Consider a code with only four valid code words 0000000000,0000011111,1111100000,1111111111. This code has distance 5. If the code word arrived is 0000000111 then the original code word must be

(1) 0000011111

(2)0000000000

(3) 1111100000

(4) 1111111111

Solution (1)

2t+1=5

2t=4

t=2

So error of 2 bit so solution is (1)

Q3 If algorithm A and another algorithm b take Log(n) and ✔n  microseconds,To solve a problem the the largest size of n of a problem these algorithm can solve in one second are

Solution

logn<106

n<2 power 106

✔n<106

square both side

n<1012

Q4  The following program is stored in memory unit of the basic computer. What is the content of the accumulator after the execution of program?

Location   Instruction

210            CLA

211             ADD 217

212             iNC

213             STA  217

214            LDA 218             

215           CMA

216           AND  217

217            1234H

218            9CE2H

(1) 1002 H

(2) 2011 H

(3) 2022 H

(4) 0215 H

Solution (4)

first clear accumulator

accumulator hold 1234 H

0001  0010  0011 0100

                                +1

0001  0010   0011  0101

store 217 content

accumulator hold  9CE2H

1001  1100 1110 0010 

complement 

0110  0011 0001  1101

AND accumulator content and stored 217 content 

0110  0011 0001  1101

AND

0001  0010   0011  0101

result

0000    0010   0001   0101

0215 H

Q5 Modifying the software by restructuring is called

(1) Adaptive maintenance

(2) Corrective maintenance

(3) Perfective  maintenance

(4) Preventive maintenance 

Solution (4) Preventive maintenance

Q6  Consider the following properties

A reflexive

B Anti-symmetric

C Symmetric

Let A ={a,b,c,d,e,f,g} and R={(a,a),(b,b),(c,d),(c,g),(d,g),(e,e),(f,f),(g,g) be a relation on A . Which of the property satisfied by the relation R?

(1) Only A

(2) Only C

(3) Both A and B

(4) B and not A

Solution (4)

Not reflective because no diagonal pair(c,c),(d,d)

Not Symmetric (c,d) is exit in relation but not (d,c)

Q7  Which of the following UML diagrams has a static view?

(1) Collaboration diagram.

(2) Use-Case diagram.

(3) State chart diagram.

(4) Activity diagram

Solution (2)  Use-case diagram.

Q8 Suppose you are compiling on a machine with 1-byte chars ,2-byte short,4-byte int and 8-byte doubles and the alignment rules that require the address of every primitive data element to be an integer multiple of element size .Suppose further that the compiler is not permitted to reorder fields padding is used to ensure alignment .How much space will be consumed by the array?

struct

{

short s;

char c;

short t;

char d;

double r;

int i;

}A[10];

(1) 150 bytes

(2) 320 bytes

(3) 240 bytes

(4) 200 bytes

Solution (4)

100/2    100,101

102/1     102

103/2      not divide by 2 so use as padding 

104/2      104,105

106/1       106

107/8      padding

108/8     padding

109/8     padding

110/8      padding

111/8     padding

112/8     112 to 120 

121/4     padding

122/4      padding

123/4      padding

123-100+1

=24

=24*10=240 bytes.

Q 9 Arrange the types of machine in descending order of complexity.

(A) SISD

(B) MIMD

(C) SIMD

Solution MIMD then SIMD then SISD

Q 10  Match LIST I with LIST II

Let R1={(1,1),(2,2),(3,3)} and R2={(1,1),(1,2),(1,3),(1,4)}

List I                                 List II

(A) R1⋃ R2                          (I) {(1,1),(1,2)(1,3)(1,4)(2,2)(3,3)}

(B) R1-R2                             (II) {(1,1)

(C) R1⋂ R2                          (III) {(1,2),(1,3),(1,4)}

(D) R2-R1                             (IV) {(2,2),(3,3)}

Solution

R1⋃ R2    contain all the element of R1 and R2 .So A match with (I).

R1-R2      contain  element of R1 not R2 .So (B) match with (IV)

 R1⋂ R2     contain common element of R1 and R2 . So (C) match with (II).

R2-R1           contain  element of R2 not R1 .So (D) match with (III)




  














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