Computer Science

1) Half adder is an example of ?
a.    Combinational Circuits
b.    Sequential Circuits
c.    Asynchronous Circuits
d.    None of these
 
Answer = A
Explanation: Combinational circuits are the circuits whose output depends on the inputs of the same instant of time.

2) In JK flip flop same input, i.e at a particular time or during a clock pulse, the output will oscillate back and forth between 0 and 1. At the end of the clock pulse the value of output Q is uncertain. The situation is referred to as ?
a.    Conversion condition
b.    Race around condition
c.    Lock out state
d.    None of these
 
Answer = B
Explanation:A race around condition is a flaw in an electronic system or process whereby the output and result of the process is unexpectedly dependent on the sequence or timing of other events.

3) In a JK flip flop, if j=k, the resulting flip flop is referred to as ?
a.    D flip flop
b.    T flip flop
c.    S-R flip flop
d.    None of these
 
Answer = C
Explanation: In JK flip flop if both the inputs are same then the flip flop behaves like SR flip flop.

4) Master slave flip flop is also referred to as ?
a.    Level triggered flip flop
b.    Pulse triggered flip flop
c.    Edge triggered flip flop
d.    None of these
 
Answer = B
Explanation:The term pulse triggered means the data is entered on the rising edge of the clock pulse, but the output does not reflect the change until the falling edge of clock pulse.

5) Fetch and decode cycle is required in ?
a.    Direct addressing
b.    Immediate addressing
c.    Indirect addressing
d.    None of above
 
Answer = B
Explanation:Fetch and decode cycle is required in Immediate addressing because it stores the operand directly on which the operation is performed.

6) Valid bit in each cache is associated with ?
a.    Each memory byte in cache
b.    Each memory word in cache
c.    One bit with the all memory words
d.    None of above

Answer = D
 
7) In J-K flip flop the function K=J is used to realize ?
a.    D flip flop
b.    S-R flip flop
c.    T flip flop
d.    Master slave flip flop
 
Answer = D
Explanation: T flip flop allows the same inputs. So if in JK flip flop J = K then it will work as T flip flop.
 
8) An encoder has 2n input lines and ..... output lines ?
a.    2
b.    n
c.    2*n
d.    n*n
 
Answer = B

9) ASCII code for alphabet character requires ..... bits ?
a.    16
b.    15
c.    8
d.    7

Answer = D
 
10) The basic limitation of FSM is that ?
a.    An FSM can remember arbitrary large amount of information
b.    An FSM sometimes recognize grammars that are not regular
c.    It sometimes fails to recognize grammar that are regular
d.    All of the above comments are true
 
Answer = A
Explanation: FSM stands for Finite State Machine.

11) What is the hexadecimal equivalent of a binary number 10101111 ?
a.    AF
b.    9E
c.    8C
d.    All of above
e.    None of above
 
Answer = A
 
12) A NOR gate recognizes only the input word whose bits are ?
a.    0's and 1's
b.    1's
c.    0's
d.    0's or 1's
e.    None of above
 
Answer = C
   
13) The operation which is commutative but not associative is ?
a.    AND
b.    OR
c.    EX-OR
d.    NAND
 
Answer = D
   
14) All digital circuits can be realized using only ?
a.    EX-OR gates
b.    Half adders
c.    Multiplexers
d.    OR gates
 
Answer = B
   
15) The XOR gates are ideal for testing parity because even parity words produces a ...... output and odd parity word produces a ....... output ?
a.    low, high
b.    high, low
c.    odd, even
d.    even, odd
e.    None of above
 
Answer = A

16) Flip flop output is always  ?
a.    Complementary
b.    Independent of each other
c.    the same
d.    same as inputs
e.    None of above
 
Answer = A
   
17) A half adder adds ..... bits ?
a.    16
b.    10
c.    8
d.    2
e.    None of above
 
Answer = D
 
18) How many flip - flop circuits are needed to divide by 16 ?
a.    Two
b.    Four
c.    Eight
d.    Sixteen
 
Answer = C
   
19) A flip flop is a ..... elements that stores a 216 binary digits as a low or high voltage ?
a.    chip
b.    bus
c.    I/O
d.    memory
e.    None of above
 
Answer = D
   
20) A positive AND gate is also a negative ?
a.    NAND gate
b.    AND gate
c.    NOR gate
d.    OR gate
e.    None of these
 
Answer = D
   
21)  Which of the following is a minimum error code ?
a.    Octal code
b.    Binary code
c.    Gray code
d.    Excess-3 code
 
Answer = C
   
22) In a positive edge triggered JK flip flop, a low J and low K produces ?
a.    High state
b.    Low state
c.    toggle state
d.    no change
 
Answer = D
Explanation:  In JK Flip Flop if J = K = 0 then it holds its current state. There will be no change.

23)  Negative numbers can't be represented in ?
a.    signed magnitude form
b.    1's complement form
c.    2's complement form
d.    None of above
 
Answer = D
   
24) Which of the following architecture is not suitable for realising SIMD ?
a.    Vector processor
b.    Array processor
c.    Von Neumann
d.    All of above
 
Answer = C
   
25) The XOR operator + is ?
a.    commutative
b.    associative
c.    distributive over AND operator
d.    A and B
 
Answer = D
Explanation: As  A + B = B + A  and  A + ( B + C) = (A + B ) + C
                     Hence it is commutative and associative.

26)  The binary equivalent of the Gray code 11100 is..... ?
a.    10111
b.    00111
c.    01011
d.    10101
 
Answer = A
Explanation: The rule for changing the Gray code to binary is that first bit remains the same and the next bit is obtained by adding the first LSB of binary to the second LSB of Gray code and so on... So the answer of the question is 10111.

27) An assembler that runs on one machine but produces machine code for another machine is called ?
a.    simulator
b.    emulator
c.    cross assembler
d.    boot strap loader
 
Answer = C
Explanation:  Cross assembler is an assembler which runs on one type of processor and produces machine code for another.

28) Which of the following unit can be used to measure the speed of a computer ?
a.    SYPS
b.    MIPS
c.    BAUD
d.    FLOPS
e.    B and D
 
Answer = E
Explanation:  MIPS measures the execution speed of computers CPU but not the whole system. FLOPS is a measure of computer's performance especially in the field of scientific calculations that makes heavy use of floating point calculations.

29)  Which of the following logic families is well suited for high speed operations?
a.    TTL
b.    ECL
c.    MOS
d.    CMOS
 
Answer = B
Explanation: ECL is used for high speed applications because of its price and power demands.

30) Which of the following comments about half adder are true?
a.    It adds 2 bits
b.    It is called so because a full adder involves two half adders
c.    It does half the work of full adder
d.    It needs two inputs and generates two outputs
e.     A, B and D
 
Answer = E
Explanation:  No Explanation

31) The minimum number of cards to be dealt from an arbitrarily shuffled deck of 52 cards to guarantee that three cards are from some same suit is ?
a.    8
b.    3
c.    9
d.    12
 
Answer = C

32) Context free languages are closed under ?
a.    union, intersection
b.    Intersection , complement
c.    union , kleene star
d.    Complement , kleene star
 
Answer = C

33) Let R be a symmetric and transitive relation on a set A. Then ?
a.    R is reflexive and hence a partial order
b.    R is reflexive and hence an equivalence relation
c.    R is not reflexive and hence not an equivalence relation
d.    None of above
 
Answer = D