WBUT Exam Papers CS Computer Organization B Tech 3rd Sem 2010-11

WBUT Exam Papers  CS Computer Organization

B Tech 3rd Sem 2010-11


Time Allotted : 3 Hours

The figures in the margin indicate full marks.

Candidates are required to give their answers in their own words ‘    as far as practicable.

GROUP-A ( Multiple Choice Type Questions )

  1. Choose the correct alternatives for the following :

10×1 = 10

i)              From a Source Code, a compiler can detect

b)        Logical errors

d) None of these.

ii)            The purpose of ROM in a Computer System is

a)            to store constant data required for computers own use

b)            to help reading from memory

c)            to store application program /

d) to store 0,s in memoiy.


iii)          Which one does not posses the characteristics of a ‘ memory element ?           .

eO A toggle swith                       b) A lamp

c) An AND gate                           d) None of these.

iv)          Data from memory location after fetching is deposited by memory in

a     MAR       b) MBR

c) IR                                            d) Status Register.

v)            How many minimum, NAND gates are required to make a flip-flop ?

a)         4 b) 3

c)          2 d) 5.

vi)          Virtual memory system allows the employment of

a)            More them address space

b)            The full address space


c)             More than hard disk capacity

d)            None of these.

vii)         A system has 48-bit virtual address, 36-bit physical address and 128 MB main memory. How many virtual and physical pages can the address space support ?


2 36, 2 24           b) 2 12, 236

c) 2 24, 2 34                                   d) 2 34 2 36 .

viii)       A UART is an example of

a)            serial asynchronous data transmission ship

b)             PIO

c)             DMA controller

d)            none of these.

ix)           A priority interrupt may be accomplished by

a)            Polling

b)             Daisy chain

c)             Parallel method of priority interrupt

d)            All of these.

CS/B.Tech(CSE) /SEM-3/CS-303/2010-11

x)             Control program memory can be reduced by

a)            Horizontal format

b)            Vertical format micro-program

c)             Hardwired control unit

d)            None of these.


( Short Answer Type Questions)Answer any three of the following. 3×5= 15

  1. a) A digital computer has a common bus system for 16

registers of 32-bits each. The bus is constructed with multiplexers.

i)              How many selection inputs are there in each multiplexer ?

ii)            What size of multiplexers are needed ?

iii)          How many multiplexers are there in the bus ?

•b) Why do most computers have a Common bus system ?

3    + 2

  1. Draw the logic diagram of a common bus which connects 4 registers of 4-bit each using tristate buffers.   5


 What is virtual memory ? Why is it called virtual ? Write the advantages of Virtual memory.                          2+1+2

What is programmed I/O technique ? Why is it not very useful ? 3 + 2

Draw the block diagram and explain the functionality of

micro-programmed control unit.                                                5

Answer any three of the following. 3×15-45

£0 Explain the difference between associative & set associative cache mapping technique.

b)           With the help of following information, determine the size of sub-fields ( in bits ) in the address for Direct mapping, Associative mapping & Set associative mapping :

  • 512 MB main memory & 2 MB cache memory
  • The address space of this processor is 256 MB
    • The block size is 256 bytes
    • There are 16 blocks in a cache set.

c)            Briefly explain the two write policies, write through and

write back for cache design. What/ sire we getting the

advantages and disadvantages of both the methods ?4    + 6 + 5


8. a) With the help of suitable diagram, explain the advantage of cany look ahead adder over conventional parallel adder.

b)             If a CPU has 8-bit data bus & 16-bit address bus draw the connection diagram for this CPU with 4 256*8 RAM &

1 512*8 ROM.

c)             Show the bus connection with a CPU to connect four RAM chips of size 256 x 8-bits each and a ROM chip of 512 x 8-bits size. Assume the CPU has $-bit data bus and 16-bit address bus. Clearly specify generation of chip select signals.

d)            What is dirty bit ?                                                 5 + 4 + 4 + 2

  1. a) Explain Booth Multiplication Algorithm for signed 2’s

complement numbers with proper flow-chart. Illustrate this with an example by multiplying ( – 9 ) x ( – 13 ).

b)             Explain destructive read out & non-destructive read out of memory system.   ( 5 + 5 ) + 5

  1. a) Explain non-restoring division algorithm and explain the

hardwire diagram. Perform the Restoring division operation with 19 divided by 8.

b)            What is baladies anomaly for* page replacement technique ? Explain with example. ( 3 + 2 + 5 ) + 5


  1. a) What are the different types of DMA controllers & how do they differ in their functioning ?

b)            Explain the basic DMA. operations for transfer of data between memory & peripherals.

c)             Differentiate between memory mapped I/O & I/O mapped I/O.           5 + 5 + 5



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