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ECE : Digital Electronics - Quiz(MCQ)
1 .
What is Digital Electronics?
A)
Engineering of devices that digital signal
B)
Engineering of devices that produce digital signal
C)
Field of electronics involving the study of digital signal
D)
All of the above

Correct Answer :   All of the above

Explanation : Digital electronics is a branch of electronics concerned with the study of digital signals as well as the design of systems that use or generate them. For electronics, gadgets, and equipment, “boolean logic” and “discrete signal electronics” are used.

2 .
What is a Circuit?
A)
Open-loop through which electrons can pass
B)
Closed-loop through which electrons can pass
C)
Closed-loop through which Neutrons can pass
D)
None of the above

Correct Answer :   Closed-loop through which electrons can pass

Explanation : A circuit is a closed-loop through which electrons can pass. Electrical energy is provided in the circuit by a source of electricity, such as a battery.

3 .
Which number system has a base 16
A)
Octal
B)
Binary
C)
Hexadecimal
D)
Decimal

Correct Answer :   Hexadecimal

Explanation : Hexadecimal is a number system with a base 16. We can divide the word HEXA+DECIMAL for better understanding; it means 6 and 10 make 16. It is the easiest way to write and count numbers represented in terms of base 16. There are sixteen distinct digits in the hexadecimal system, it starts from 0, 1,2,3,4,5,6,7,8,9, A, B, C, D, E and end to F. Where A= 10, B=11, C=12, D=13, E=14, F=15. It is usually represented by 4 bits in binary number system by 8421 code.

4 .
What is a digital-to-analog converter?
A)
It stores digital data on the computer.
B)
It converts electrical power into mechanical power.
C)
It converts alternating current (AC) into direct current (DC).
D)
It takes the digital data from an audio CD and converts it to a useful form.

Correct Answer :   It takes the digital data from an audio CD and converts it to a useful form.

Explanation : A "digital-to-analog converter" or DAC refers to an electronic device that converts the digital signals (discrete-time signal) to an analog signal (Continuous-time signal). In other words, we can say that an electronic device converts the signal of 0 and 1 (Binary) into the analog form. For example, the amplitude of the output signal varies according to the input values.

5 .
Which of the following is correct for Digital Circuits?
A)
Easier to perform error detection and correction with digital signal
B)
Less susceptible to noise or degradation in quality
C)
Use transistors to create logic gates to perform Boolean logic
D)
All of the above

Correct Answer :   Easier to perform error detection and correction with digital signal

Explanation : A digital circuit is a circuit that has a signal that must fall into one of two discrete levels. Each level is read as one of two states (on/off, 0/1, true/false, for example). To perform Boolean logic, digital circuits use transistors to generate logic gates.

6 .
The fan put of a 7400 NAND gate is
A)
2TTL
B)
5TTL
C)
8TTL
D)
10TTL

Correct Answer :   10TTL

7 .
The universal gate is ___________
A)
OR gate
B)
NAND gate
C)
AND gate
D)
None of the above

Correct Answer :   NAND gate

8 .
2's complement of binary number 0101 is
A)
1111
B)
1110
C)
1011
D)
1101

Correct Answer :   1011

Explanation : 1's complement of 0101 is 1010 and 2's complement is 1010+1 = 1011.

9 .
An OR gate has 4 inputs. One input is high and the other three are low. The output
A)
is low
B)
is high
C)
is alternately high and low
D)
may be high or low depending on relative magnitude of inputs

Correct Answer :   is high

Explanation : In OR any input high means high output.

10 .
Decimal number 10 is equal to binary number
A)
1010
B)
1110
C)
1000
D)
1001

Correct Answer :   1010

Explanation : 1010 = 8 + 2 = 10 in decimal.

11 .
The following hexadecimal number (1E.43)16 is equivalent to
A)
(36.206)₈
B)
(36.506)₈
C)
(35.506)₈
D)
(35.206)₈

Correct Answer :   (36.206)₈

Explanation : If you want to convert a hexadecimal number into an octal number, the first thing you need to do is convert a hexadecimal number into binary form by writing the binary equivalent of each digit in the form of 4 bits. Once you write the number into binary form, you need to group the binary equivalent in 3 bits, then for each of the three bits, the respective digit is written.

(1E.43)₁₆ = (0001 1110.0100 0011)₂

= (00011110.01000011)â‚‚

= (011110.010000110)â‚‚

= (011 110.010 000 110)â‚‚

= (36.206)₈

12 .
How many entries will be in the truth table of a 4-input NAND gate?
A)
6
B)
8
C)
16
D)
32

Correct Answer :   16

Explanation : A NAND gate is a universal logic gate that performs the negation (NOT) of an AND logic operations in digital circuits.

As we know,

Y = 2ⁿ Y number of Entries in the truth table

Where,

n = number of inputs.

13 .
Which of the following is an example of a digital Electronic?
A)
Computers
B)
Digital cameras
C)
Information appliances
D)
All of the above

Correct Answer :   All of the above

Explanation : Computers, information appliances, digital cameras, digital televisions, flash memory, key USB memory, mobile phones, hard discs, and computer memory devices are examples of digital electronics. After analog signals have been transformed to digital form, digital signal processing is applied to them.

14 .
Which of the following is a type of digital logic circuit?
A)
Combinational logic circuits
B)
Sequential logic circuits
C)
Both (A) and (B)
D)
None of the above

Correct Answer :   None of the above

Explanation : There are two main types of digital logic circuits in digital electronics. They are:
a) Combinational logic circuits
b) Sequential logic circuits

15 .
An OR gate has 6 inputs. The number of input words in its truth table are
A)
6
B)
32
C)
64
D)
128

Correct Answer :   64

16 .
In which of the following base systems is 123 not a valid number?
A)
Base 3
B)
Base 6
C)
Base 8
D)
Base 10

Correct Answer :   Base 3

17 .
A device which converts BCD to seven segment is called
A)
encoder
B)
decoder
C)
multiplexer
D)
None of the above

Correct Answer :   decoder

Explanation : Decoder converts binary/BCD to alphanumeric.

18 .
In 2's complement representation the number 11100101 represents the decimal number
A)
-31
B)
+37
C)
-27
D)
+27

Correct Answer :   -27

Explanation : A = 11100101. Therefore A = 00011010 and A' = A + 1 = 00011011 = 16 + 8 + 2 + 1 = 27. Therefore A = -27.

19 .
A decade counter skips
A)
binary states 0000 to 0011
B)
binary states 1000 to 1111
C)
binary states 1111 to higher
D)
binary states 1010 to 1111

Correct Answer :   binary states 1010 to 1111

Explanation : A decade counter counts from 0 to 9. It has 4 flip-flops. The states skipped are 10 to 15 or 1010 to 1111.

20 .
A ring counter with 5 flip flops will have
A)
5 states
B)
10 states
C)
32 states
D)
Infinite states

Correct Answer :   5 states

21 .
In the expression A + BC, the total number of minterms will be
A)
2
B)
3
C)
4
D)
5

Correct Answer :   5

Explanation :

The min terms are ABC + ABC + AB C + ABC + ABC.

22 .
Which of the following is non-saturating?
A)
TTL
B)
ECL
C)
CMOS
D)
Both (A) and (C)

Correct Answer :   ECL

Explanation : Since it is non-saturating, ECL has low propagation delay.

23 .
The number of digits in octal system is
A)
8
B)
9
C)
10
D)
12

Correct Answer :   8

Explanation : The octal system has 8 digits 0 to 7.

24 .
How many bits are needed to store one BCD digit?
A)
2 bits
B)
3 bits
C)
4 bits
D)
None of the above

Correct Answer :   4 bits

Explanation : BCD stands for Binary Coded Decimal. It is a type of binary encoding where each decimal digit is represented by a fixed number of bits, usually 4. It is also called 8421 code to represent the maximum number 15. BCD can encode only from 0-9. For example, Decimal number 456, its equivalent BCD code is 0100 0101 0110

25 .
Convert (312)₈ into decimal
A)
(201)₁₀
B)
(202)₁₀
C)
(203)₁₀
D)
(204)₁₀

Correct Answer :   (202)₁₀

Explanation : Octal to decimal conversion is usually obtained by multiplying 8 to the power of base along with the value at the index position.

(312)₈ = 3 * 8² + 1* 8¹ + 2* 8⁰

= 192 + 8 +2 = (202)₁₀

26 .
Which of the following options comes under the non – saturated logic family in Digital Electronics?
A)
High-Threshold Logic
B)
Diode – Transistor Logic
C)
Integrated – injection Logic
D)
Emitter – coupled Logic

Correct Answer :   Emitter – coupled Logic

Explanation : Bipolar IC’s can be classified as saturated and non – saturated logic families. ECL (Emitter – coupled Logic) and Schottky TTL are said to come under the non – saturated logic family.

27 .
What is a switching function that has more than one output called in Digital Electronics?
A)
Multi-gate function
B)
Multiple-gate function
C)
Multi-output function
D)
Multiple-output function

Correct Answer :   Multi-output function

Explanation : multi-output function is a switching function that will have more than one output. A multiple output gate network will have the digital logic circuit corresponding to the multi-output function.

28 .
In case of OR gate, no matter what the number of inputs, a
A)
1 at any input causes the output to be at logic 1
B)
1 at any input causes the output to be at logic 0
C)
0 any input causes the output to be at logic 0
D)
0 at any input causes the output to be at logic 1.

Correct Answer :   1 at any input causes the output to be at logic 1

29 .
The number of Boolean functions that can be generated by n variables is equal to
A)
2ⁿ
B)
2²ⁿ
C)
2²ⁿ⁻¹
D)
2ⁿ⁻¹

Correct Answer :   2²ⁿ

30 .
The expression Y = πM (0, 1, 3, 4) is
A)
POS
B)
SOP
C)
Hybrid
D)
None of the above

Correct Answer :   POS

31 .
Decimal 43 in hexadecimal and BCD number system is respectively.
A)
B2, 01000011
B)
B2, 01000100
C)
2B, 00110100
D)
2B, 01000011

Correct Answer :   2B, 01000011

Explanation : (43)₁₀ = (2B)₁₆

(43)₁₀ = (01000011)₂

32 .
The number of bits in ASCII is
A)
9
B)
12
C)
7
D)
10

Correct Answer :   7

Explanation : ASCII is a 7 bit code.

33 .
4 bit 2's complement representation of a decimal number is 1000. The number is
A)
+ 8
B)
0
C)
-7
D)
- 8

Correct Answer :   - 8

Explanation : (a) and (d) both are option, But there is meaning to represent a positive number in 2's complement form, we take complement representation for negative number only. Therefore most appropriate number is "-8".

34 .
In a D latch
A)
data bit D is fed to S input and D to R input
B)
data bit D is fed to R input and D to S input
C)
data bit D is fed to both R and S inputs
D)
data bit D is not fed to any input

Correct Answer :   data bit D is fed to S input and D to R input

Explaination :

35 .
A 4 : 1 multiplexer requires __________ data select line.
A)
1
B)
2
C)
3
D)
4

Correct Answer :   2

Explanation : 2² = 4. Hence 2 select lines.

36 .
The number of unused states in a 4 bit Johnson counter is
A)
2
B)
4
C)
8
D)
12

Correct Answer :   8

Explanation : Total state = 2ⁿ = 2⁴ = 16

Used state = 2ⁿ = 2 x 4 = 8

Unused state = 16 - 8 = 8.

37 .
It is desired to display the digit 7 using a seven segment display. The LEDs to be turned on are
A)
a, b, c
B)
b, c, d
C)
c, d, e
D)
a, b, d

Correct Answer :   a, b, c

Explanation :

38 .
100101â‚‚ is equal to decimal number
A)
17
B)
21
C)
37
D)
47

Correct Answer :   37

Explanation : 32 + 4 + 1 = 37 in decimal.

39 .
A SCR (Silicon Controlled Rectifier) is a
A)
Device with 1 junction
B)
Device with 2 junctions
C)
Device with 3 junctions
D)
Device with 4 junctions

Correct Answer :   Device with 2 junctions

Explanation : SCR stands for Silicon Controlled Rectifier; it is a family of thyristors with the same property as thyristors. It is a semiconductor device with three junctions. They are of two types: npnp and pnpn. For the pnpn type, the inner player has a gate terminal, the outer player has an anode terminal, and the outer n layer has a cathode terminal. The SCR controls the flow of anode current once the gate is triggered.

40 .
Which semiconductor device is not a current triggering device?
A)
GTO
B)
TRIAC
C)
MOSFET
D)
Thyristor

Correct Answer :   MOSFET

Explanation : MOSFET stands for Metal Oxide Semiconductor Field Effects Transistor. It is a semiconductor device that is extensively used for switching and amplifying the signals in digital devices.

The MOSFET is the main part of any integrated circuits, and it can be designed in a single chip because of its small sizes. It is a four-terminal device: source(S), gate(g), drain(d), and body(b).

The body(b) is connected to the source, making MOSFETS a three-terminal device like a field-effect transistor. MOSFETS can be used in both digital and Analog circuits, so it is one of the widely used transistors in digital circuits.

41 .
Which of these sets of logic gates are known as universal gates?
A)
OR, NOT, XOR
B)
XOR, NAND, OR
C)
NOR, NAND, XNOR
D)
NOR, NAND

Correct Answer :   NOR, NAND

Explanation : NAND or NOR gates are used to design all other logic gates, so; they are termed universal gates.

42 .
What is the addition of the binary number 101001+ 010011=?
A)
111100
B)
010100
C)
000111
D)
101110

Correct Answer :   111100

Explanation : If you want to add any binary number, first, you need to know the binary addition rules.

0 + 1 = 1

1 + 0 = 1

0 + 0 = 0

1 + 1 = 0 (with carry 1)

101001+ 010011 = 111100

43 .
Which characteristic of IC in Digital Circuits represents a function of the switching time of a particular transistor?
A)
Fan – in
B)
Fan – out
C)
Propagation delay
D)
Power dissipation

Correct Answer :   Propagation delay

Explanation : Propagation delay represents a function of the switching time of a particular transistor or MOSFET. The propagation delay helps in determining the speed of logic circuits.

44 .
When can one logic gate drive many other logic gates in Digital Electronics?
A)
When its output impedance is low and the input impedance is low
B)
When its output impedance is high and the input impedance is low
C)
When its output impedance is high and the input impedance is high
D)
When its output impedance is low and the input impedance is high

Correct Answer :   When its output impedance is low and the input impedance is high

Explanation : When the output impedance of a logic gate is low and its input impedance is high, then one logic gate can drive many other logic gates. High impedance in the output will resist the driving of many logic gates.

45 .
Which of the following digital logic circuits can be used to add more than 1 – bit simultaneously?
A)
Serial adder
B)
Ripple – carry adder
C)
Full – adder
D)
Half – adder

Correct Answer :   Ripple – carry adder

Explanation : A Ripple – carry adder is a parallel binary adder in which the addition of more than 1 – bit data can be done simultaneously. The inputs to a parallel circuit can be sent and processed at once unlike series circuits in which inputs are sent one by one.

46 .
Which mechanism allocates the binary value to the states in order to reduce the cost of the combinational circuits?
A)
State Reduction
B)
State Assignment
C)
State Evaluation
D)
State Minimization

Correct Answer :   State Assignment

47 .
Positive logic in a logic circuit is one in which
A)
logic 0 voltage level is lower than logic 1 voltage level.
B)
logic 0 voltage level is higher than logic 1 voltage level
C)
logic 0 and 1 are represented by 0 and positive voltage respectively
D)
logic 0 and, -1 are represented by negative and positive voltages respectively

Correct Answer :   logic 0 voltage level is lower than logic 1 voltage level.

48 .
Digital circuit can be made by the repeated use of ___________
A)
OR gates
B)
NOT gates
C)
NAND gates
D)
None of the above

Correct Answer :   NAND gates

49 .
Pick out the CORRECT statement:
A)
Each hexadecimal digit can be represented as a sequence of three binary symbols
B)
In a positional number system, each symbol represents the same value irrespective of its position
C)
It is not always possible to find the exact binary
D)
The highest symbol in a position number system as a value equal to the number of symbols in the system

Correct Answer :   It is not always possible to find the exact binary

50 .
A Karnaugh map with 4 variables has
A)
2 cells
B)
4 cells
C)
8 cells
D)
16 cells

Correct Answer :   16 cells

Explanation : 2⁴= 16.

51 .
An 8 bit data is to be entered into a parallel in register. The number of clock pulses required is
A)
1
B)
2
C)
4
D)
8

Correct Answer :   1

Explanation : In a parallel in register only one pulse is needed to enter data.

52 .
A universal shift register can shift
A)
From left to right
B)
From right to left
C)
Both from left to right and right to left
D)
None of the above

Correct Answer :   Both from left to right and right to left

53 .
For the binary number 11101000, the equivalent hexadecimal number is
A)
F 8
B)
E 8
C)
F 9
D)
E 9

Correct Answer :   E 8

Explanation : 11 01000 = 128 + 64 + 32 + 8 = 232 in decimal = E 8 in hexadecimal.

54 .
AECF1₁₆ + 15ACD₁₆ = __________ .
A)
A234F₁₆
B)
C47BE₁₆
C)
A1111₁₆
D)
C47BB₁₆

Correct Answer :   C47BE₁₆

Explanation : Convert to decimal, add and change the result to hexadecimal.

55 .
Out of latch and flip flop, which has clock input?
A)
Flip flop only
B)
Latch only
C)
Both latch and flip flop
D)
None of the above

Correct Answer :   Flip flop only

Explanation : This the main difference between latch and flip-flop. Only flip-flop has clock input.

56 .
A mod 4 counter will count
A)
from 0 to 4
B)
from 0 to 3
C)
from any number n to n + 4
D)
None of the above

Correct Answer :   from 0 to 3

Explanation : Mod 4 counter has 4 states, 0 to 3.

57 .
Which of the following finds application in pocket calculators?
A)
TTL
B)
ECL
C)
CMOS
D)
None of the above

Correct Answer :   CMOS

Explanation : Because of low power consumption CMOS is used in pocket calculators.

58 .
Octal number 12 is equal to decimal number
A)
5
B)
8
C)
9
D)
10

Correct Answer :   10

Explanation : 12 in octal = 8 + 2, i.e., 10 in decimal.

59 .
Decimal number 46 in excess 3 code =
A)
0111 1001
B)
1000 1001
C)
0111 1111
D)
1000 1111

Correct Answer :   0111 1001

Explanation : Decimal 46 in excess 3 code = 46 + 33 = 79 in decimal = 0111 1001 in 4 bit binary.

60 .
A 4 input AND gate is equivalent to
A)
4 switches in parallel
B)
4 switches in series
C)
2 switches in series and 2 in parallel
D)
three switches in parallel and one in series

Correct Answer :   4 switches in series

Explanation : All the switches have to be closed so that the circuit can be made. In AND gate all the inputs have to be high for output to be high.

61 .
The circuit of the given figure is
A)
full adder
B)
shift register
C)
decade counter
D)
full subtractor

Correct Answer :   full subtractor

Explaination :

62 .
The no. of comparators required in a 3 bit comparator type ADC is
A)
2
B)
3
C)
7
D)
8

Correct Answer :   7

Explanation : Number of comparators = 2ⁿ - 1 = 2³ - 1 = 7.

63 .
The number of counter states which an 8 bit stair step A/D converter has to pass through before conversion takes place is equal to
A)
1
B)
32
C)
120
D)
256

Correct Answer :   256

Explanation : 2⁸ = 256.

64 .
74 HC series can sink upto 4 mA. The 74 LS series has IIL(max) - 0.4 mA. How many 74 LS inputs be driven by 74 HC output?
A)
8
B)
10
C)
100
D)
None of the above

Correct Answer :   10

Explanation : 4/0.4 = 10

65 .
An 8 bit transistor register has output voltage of low-high-low-high-low-high-low-high. The decimal number stored is
A)
85
B)
95
C)
105
D)
115

Correct Answer :   85

Explanation : 01010101 in binary and 64 + 16 + 4 + 1 = 85 in decimal.

66 .
The number of cells in a 4 variable K map is
A)
4
B)
8
C)
16
D)
32

Correct Answer :   16

Explanation : 2⁴ = 16.

67 .
A 3 bit up-down counter can count from
A)
000 to 111
B)
111 to 000
C)
000 to 111 and also from 111 to 000
D)
None of the above

Correct Answer :   000 to 111 and also from 111 to 000

Explanation : Since it is an up-down counter it can count upwards or downwards.

68 .
The maximum counting range of a four stage counter using IC 74193 is
A)
0 to 131071
B)
0 to 65535
C)
0 to 4093
D)
0 to 1023

Correct Answer :   0 to 65535

Explanation : IC 74193 is a divide by 16 counter.

Since 4 stages are used, counting range = 16⁴ = 65536.

69 .
A 3 input NAND gate is to be used as inverter. Which of the following will give better results?
A)
The two unused inputs are left open
B)
The two unused inputs are left 0
C)
The two unused inputs are connected to 0
D)
The two unused inputs are connected to 1

Correct Answer :   The two unused inputs are connected to 1

Explanation : Unused inputs should be given high input.

70 .
The density of dynamic RAM is
A)
the same as static RAM
B)
less than that of static RAM
C)
more than that of static RAM
D)
either equal or less than that of static RAM

Correct Answer :   more than that of static RAM

Explanation : Dynamic RAM has higher packing density and requires lesser space.

71 .
If memory chip size is 256 x 1 bits, the number of chips required to make 1 k byte memory is
A)
8
B)
12
C)
24
D)
32

Correct Answer :   32

Explanation : (1024 x 8)/(256 x 1 ) = 32.

72 .
The function Y = AC + BD + EF is
A)
SOP
B)
POS
C)
Hybrid
D)
None of the above

Correct Answer :   SOP

Explanation : It is sum of products.

73 .
EPROM can be
A)
EEPROM
B)
UVPROM
C)
Both UVPROM and EEPROM
D)
None of the above

Correct Answer :   Both UVPROM and EEPROM

Explanation : Both ultra violet and electric pulses are used for erasing.

74 .
The function of interface circuit is
A)
to match output conditions of driver with input conditions of load device
B)
to match output conditions of load device with input conditions of driver
C)
Both (A) and (B)
D)
Neither (A) nor (B)

Correct Answer :   to match output conditions of driver with input conditions of load device

Explanation : Output of driver stage has to be matched with input of load.

75 .
1274₁₆ - 3A7₁₆ = __________ .
A)
ACB₁₆
B)
ECD₁₆
C)
ACA₁₆
D)
AAA₁₆

Correct Answer :   ECD₁₆

Explaination : Convert to decimal, subtract and change the result to hexadecimal.

76 .
With four Boolean variables, how many Boolean expressions can be performed?
A)
16
B)
256
C)
1024 (1 K)
D)
64K (64 x 1024)

Correct Answer :   64K (64 x 1024)

Explanation :

224 = 216.

77 .
A + (B . C) =
A)
A
B)
A . B + C
C)
A . B + A . C
D)
(A + B) . (A + C)

Correct Answer :   (A + B) . (A + C)

Explanation : This is distributive law.

78 .
The inputs to a 3 bit binary adder are 111â‚‚ and 110â‚‚. The output will be
A)
101
B)
1101
C)
1110
D)
1111

Correct Answer :   1101

Explaination : Rules for binary addition.

0 + 0 = 0

0 + 1 = 1 + 0 = 1

1 + 1 = 10

i.e., 1 + 1 equals 0 with a carry of 1 to next higher column. 1 + 1 + 1 = 11

i.e., 1 + 1 + 1 equals 1 with a carry of 1 to next higher column.

79 .
A 4 bit ripple counter starts in 0000 state. When the counter reads 0010 the number of clock pulses which have occurred is
A)
2
B)
18
C)
2 or 18
D)
2 or 18 or 34

Correct Answer :   2 or 18 or 34

Explanation : At pulse 1 the state changes to 0001 and at pulse 2 it changes to 0010 Since it has a total of 16 states, the counter returns to 0000 after 16 and 32 pulses.

80 .
The number FF in hexadecimal system is equivalent to number __________ in decimal system.
A)
239
B)
240
C)
255
D)
256

Correct Answer :   255

Explanation : FF = 15 x 16 + 15 = 255.

81 .
The number of memory locations in which 14 address bits can access is
A)
1024
B)
2048
C)
4096
D)
16384

Correct Answer :   16384

Explanation : 2¹â´ = 16384.

82 .
What will be conversion rate for a counter type A/D converter contains a 4 bit binary ladder and a counter driven by a 2 MHz clock. Then conversion time
A)
125
B)
125 x 10³
C)
125 x 10⁶
D)
None of the above

Correct Answer :   125 x 10³

83 .
What will be output for decimal input 82?
A)
10 mV
B)
8 V
C)
0.82 V
D)
0.1 V

Correct Answer :   0.82 V

Explanation : Output for decimal input 82/(10000010) = 0.01 x 82 = 0.82 V.

84 .
What is the binary subtraction of 101001 - 010110 =?
A)
010011
B)
100110
C)
011001
D)
010010

Correct Answer :   010011

Explanation : If you want to subtract any binary number, first, you need to know the binary subtraction rules.

1 - 0 = 1

0 - 1 = 1 (With borrow 1)

0 - 0 = 0

1 - 1 = 0

therefore, the subtraction of 101001 - 010110 = 010011

85 .
What is the binary multiplication of 10100 * 01011 =?
A)
011011000
B)
011011100
C)
011100011
D)
011001100

Correct Answer :   011011100

Explanation : If you want to multiply any binary number, you need to know the binary multiplication rules.

1 * 0 = 0

0 * 1 = 0

0 * 0 = 0

1 * 1 = 1

therefore, the multiplication of 10100 - 01011 = 011011100

86 .
Divide the binary number: 111001 ÷ 1101 and find the reminder
A)
0101
B)
1010
C)
0011
D)
0110

Correct Answer :   0101

Explanation : If you want to divide any binary number, you need to know the binary division rule. The binary division is accomplished using the long division rule.

Therefore, the remainder of 111001 ÷ 1101 = 0101

87 .
Which gates in Digital Circuits are required to convert a NOR-based SR latch to an SR flip-flop?
A)
Two 3 input OR gates
B)
Two 2 input OR gates
C)
Two 3 input AND gates
D)
Two 2 input AND gates

Correct Answer :   Two 2 input AND gates

Explanation : Two 2 input AND gates are placed with a NOR – based S – R latch to convert it to an S – R flip – flop. One AND gate is given R in one input and clock in the other. Similarly the second AND gate is given S in one input and clock in the other.

88 .
When does a negative level triggered flip-flop in Digital Electronics changes its state?
A)
When the inputs are all zero
B)
When the inputs are all one
C)
When the clock is negative
D)
When the clock is positive

Correct Answer :   When the clock is negative

Explanation : A negative level triggered flip – flop has a NOT gate present between clock input and the input of AND gate. Thus, the negative level triggered flip – flop change its state when the clock is negative.

89 .
Which of the following options represent the synchronous control inputs in an S – R flip flop?
A)
S
B)
R
C)
Clock
D)
Both S and R

Correct Answer :   Both S and R

Explanation : The input for which the flip flop changes its state when synchronized with the clock is called the synchronous control inputs. For the S – R flip flop, both S and R are synchronous control inputs.

90 .
What would happen, if smaller logic modules are utilized for performing logical functions associated with FPGA?
A. Propagation delay will increase
B. FPGA area will increase
C. Wastage of logic modules will not be prevented
D. Number of interconnected paths in device will decrease
A)
A & B
B)
B & C
C)
A & D
D)
C & D

Correct Answer :   A & B

91 .
A debouncing circuit is
A)
A bistable MV
B)
A latch
C)
An astable MV
D)
A monostable MV

Correct Answer :   A latch

92 .
The inverter is ________.
A)
NOT gate
B)
OR gate
C)
AND gate
D)
None of the above

Correct Answer :   NOT gate

93 .
In a 4 bit ripple counter using flip flops with tpd = 40 ns, the maximum frequency can be
A)
12.5 MHz
B)
6.25 MHz
C)
3.25 MHz
D)
1.25 MHz

Correct Answer :   6.25 MHz

Explaination :

94 .
What will be FSV in 2 bit BCD D/A converter is a weighted resistor type with ER = 1V, R = 1 MΩ and Rf = 10KΩ
A)
B)
0.1 V
C)
0.9 V
D)
0.99 V

Correct Answer :   0.99 V

Explaination :

95 .
BCD equivalent of - 8₁₀ is
A)
00110
B)
11000
C)
01000
D)
10110

Correct Answer :   11000

Explanation : Decimal 8 = 1000 and - 8 = 11000.

96 .
The number of inputs and outputs in a full adder are
A)
2 and 1
B)
2 and 2
C)
3 and 2
D)
3 and 3

Correct Answer :   3 and 2

Explanation :

97 .
The number of digits in hexadecimal system
A)
8
B)
10
C)
15
D)
16

Correct Answer :   16

98 .
A NOR gate has 3 inputs A, B, C. For which combination of inputs is output HIGH
A)
A = B = C = 0
B)
A = B = C = 1
C)
A = B = 1 and C = 0
D)
A = C = 1 and B = 0

Correct Answer :   A = B = C = 0

Explanation : NOR gate gives High output when all inputs are Low.

99 .
In the toggle mode, a JK flip-flop has
A)
J = 0, K = 1
B)
J = 1, K = 1
C)
J = 0, K = 0
D)
J = 1, K = 0

Correct Answer :   J = 1, K = 1

Explanation : Toggling means switching between the two states when output changes to its complement on applying clock signal. For example, suppose you assume the initial output to be X (1 or 0), then after toggling, the output state will be X' (0 or 1, respectively). Both j and k should be 1 for toggle in JK flip flop.

100 .
A classification of integrated circuits with complexities of 30 to 300 equivalent gates on a single chip is known as?
A)
SSI
B)
LSI
C)
MSI
D)
VLSI

Correct Answer :   MSI

Explanation : The terminologies like MSI, SSI, LSI and VLSI came out from the complexity of the integrated circuit. It means the total number of transistors are fabricated on a single chip. Jack Kilby invented the first integrated circuit in 1959, so, after that, the Integrated circuit has emerged like SSI, LSI, MSI and VLSI.

In MSI (Medium Scale Integration) = 30 - 300 gates /chip (counters, multiplexers, registers)

In LSI (Large Scale Integration) = 300 - 3000 gates /chip (8-bit processors)

In SSI (Small-Scale Integration) = 3 - 30 gates /chip (logic gates, flip flops)

In VLSI (Very Large-Scale Integration) = >3000 gates / chip (16 bit and 32- bit processors)

101 .
The inverter can be classified as
A)
Power Inverter
B)
Voltage source Inverter
C)
Current source Inverter
D)
Both (B) and (C)

Correct Answer :   Both (B) and (C)

Explanation : Inverter refers to an electronic device that converts direct current (DC) to alternating current (AC). It has a wide range of applications for small appliances, TVs, DVD players, computer power supply to large electric power supply like photovoltaic solar cells.

Based on the type of the input source, Inverters are divided into two categories.

Current source inverters : In current source inverters, the input is a current source.

Voltage source inverters : In voltage source inverters, the input is a voltage source.

102 .
What must be used along with synchronous control inputs to trigger a change in the flip flop?
A)
0
B)
1
C)
Clock
D)
None of the above

Correct Answer :   Clock

Explanation : A clock must be used along with synchronous control inputs to trigger a change in the flip flop. These flip – flops may be edge – triggered or level – triggered. A change should occur only when the clock changes from 0 to 1 or vice versa.

103 .
Which of the following majorly determines the number of emitters in a TTL digital circuit?
A)
Fan – in
B)
Fan – out
C)
Propagation delay
D)
Noise immunity

Correct Answer :   Fan – in

Explanation : The TTL circuit uses multi – emitter transistors with many emitters in the input. Thus, the number of emitters is determined by the fan – in. Fan – in determines the number of inputs the particular gate can handle.

104 .
What will be the output from a D flip – flop if the clock is low and D = 0?
A)
No change
B)
0
C)
1
D)
Toggle between 0 and 1

Correct Answer :   No change

Explanation : When the clock is low, the input given to D will have no effect. This is because the set and reset pins of the NAND gates are kept high. When HIGH value is given to NAND gates the output result will be zero.

105 .
Most of the digital computers do not have floating point hardware because
A)
It is slower than software
B)
Floating point hardware is costly
C)
Of no specific reason
D)
It is not possible to perform floating point addition by hardware

Correct Answer :   Floating point hardware is costly

106 .
What is/are the configurable functions of each and every IOBs connected around the FPGA device from the operational point of view?
A)
Input operation
B)
Tristate output operation
C)
Bi-directional I/O pin access
D)
All of the above

Correct Answer :   All of the above

107 .
The binary number 10101 is equivalent to decimal number ____.
A)
12
B)
19
C)
21
D)
27

Correct Answer :   21

108 .
In 2's complement form, - 2 is
A)
1011
B)
1110
C)
1100
D)
1010

Correct Answer :   1110

Explanation :

A = 1110,

A = 0001,

A + 1 = 0001 + 1 = 0010 = 2

Therefore A = -2.

109 .
Temperature variation is a/an
A)
Analog quantity
B)
Digital quantity
C)
Either Analog or Digital quantity
D)
None of the above

Correct Answer :   Analog quantity

Explanation : Temperature variation is continuous with respect to time. So, it is an analog quantity.

110 .
1's complement of 1011001 is
A)
0101100
B)
0100111
C)
0100110
D)
0110110

Correct Answer :   0100110

Explanation : If you want to calculate 1's complement of any binary number, you need to reverse its binary bits. All the 0's to 1's and 1's to 0's.

Therefore, 1's complement of 1011001 = 0100110

111 .
2's complement of 1011011 is
A)
0100011
B)
0100011
C)
0110101
D)
0100101

Correct Answer :   0100101

Explanation : If you want to calculate 2's complement of any binary number, first you need to calculate 1's complement of that number and then add 1 to it.

2's complement of 1011011 = 0100100 + 1 = 0100101.

112 .
What are the basic gates in MOS logic family?
A)
AND and OR
B)
NAND and NOR
C)
AND and NOR
D)
NAND and OR

Correct Answer :   NAND and NOR

Explanation : The MOS logic family uses the MOSFET devices to perform its operation. NAND and NOR are the basic gates that are the building blocks of most digital circuits.

113 .
How must the output of a gate in a TTL digital circuit act when it is HIGH?
A)
Acts as a current source
B)
Acts as a current sink
C)
Acts as a voltage sink
D)
Acts as a voltage source

Correct Answer :   Acts as a current source

Explanation : If the gate output is high in a TTL circuit, the current must be given to the input of the gate being driven. Thus, the output must act as a current source. In a normal TTL circuit, about 40μA of current is drawn from the input from a output that is HIGH.

114 .
Assuming 8 bits for data, 1 bit for parity, I start bit and 2 stop bits, the number of characters that 1200 BPS communication line can transmit is.
A)
12 CPS
B)
10 CPS
C)
120 CPS
D)
None of the above

Correct Answer :   12 CPS

115 .
An AND gate will function as OR if
A)
All the inputs are ‘0’
B)
Either of the inputs is “1”
C)
All the inputs to the gates are “1”
D)
All the inputs and outputs are complemente'

Correct Answer :   All the inputs and outputs are complemente'

116 .
Which type of CPLD packaging can provide maximum number of pins on the package due to small size of the pins?
A)
QFP
B)
PGA
C)
BGA
D)
PLCC

Correct Answer :   BGA

117 .
An Digital Electronics Overflow is a__________
A)
Hardware problem
B)
Software problem
C)
User input problem
D)
Input-Output problem

Correct Answer :   Software problem

Explanation : An overflow is a software problem that takes place when the processor cannot respond to the output accurately when it gives an out-of-range result.

118 .
A digital circuit that can store only one bit is a
A)
Flip-flop
B)
Register
C)
NOR gate
D)
XOR gate

Correct Answer :   Flip-flop

Explanation : A flip-flop refers to an electronic circuit with two stable states that can be used to store the binary data (1,0). Flip-flop can store only one bit of data, either a logic 1 or 0. This logic state can be represented as the voltage on the flip-flop's output because it can be controlled to hold the logic state, effectively a 1 -bit memory.

119 .
The excess-3 code for 584 is given by
A)
100010110111
B)
100001110111
C)
100010010110
D)
100001010110

Correct Answer :   100010110111

Explanation : If you want to calculate the excess-3 code of any number, you need to add "3" to each digit of the same number. In the above problem, the addition of "3" to each digit gives you a new digit "8," "11," and "7." Hence, according to 8421 rules, the corresponding four-bit binary equivalents are 100010110111

120 .
What is the minimum distance required for single error detection according to Hamming’s analysis in Digital Electronics?
A)
1
B)
2
C)
3
D)
4

Correct Answer :   4

Explanation : According to Hamming’s analysis, a minimum distance of 2 is required for single error detection. This Hamming distance represents the number of bits that are changed from one code word to the other.

121 .
Which of these error-detecting codes enables to find double errors in Digital Electronic devices?
A)
Parity method
B)
Odd-Even method
C)
Check sum method
D)
Bit generation method

Correct Answer :   Check sum method

Explanation : Check sum enables to find double errors and also find the erroneous bits. The parity method can help in finding only single errors within a word as a double error will not change the parity bits.

122 .
What characteristic will a TTL digital circuit possess due to its multi-emitter transistor?
A)
Low inductance
B)
Low capacitance
C)
High inductance
D)
High capacitance

Correct Answer :   Low capacitance

Explanation : TTL circuit uses multi – emitter transistors which have a smaller area. The capacitance can be represented in terms of area and distance between the plates using the expressions C = Aε0/d. As “C” is directly proportional to “A”, a smaller area leads to a lower capacitance.

123 .
What value is to be considered for a "don’t care condition"?
A)
0
B)
1
C)
Either 0 or 1
D)
Any number except 0 and 1

Correct Answer :   Either 0 or 1

Explanation : A don’t care condition can take 0 or 1 according to the requirement. SOP expressions may consider it to be 1 to increase the number of 1s and POS expressions may consider it to be 0 to increase the number of 0s.

124 .
Among the logic families, the family which can be used at very high frequency greater than 100 MHz in a 4 bit synchronous counter is
A)
ECL
B)
CMOS
C)
TTLLS
D)
TTLAS

Correct Answer :   ECL

125 .
In Boolean algebra, the bar sign (-) indicates ___________.
A)
OR operation
B)
NOT operation
C)
AND operation
D)
None of the above

Correct Answer :   NOT operation

126 .
A hexadecimal odometer displays F 52 F. The next reading will be
A)
G52F
B)
F53F
C)
F52E
D)
F53O

Correct Answer :   F53O

127 .
The binary code of (21.125)10 is
A)
10101.001
B)
10101.010
C)
10100.111
D)
10100.001

Correct Answer :   10101.001

128 .
A NAND gate is called a universal logic element because
A)
It is used by everybody
B)
Many digital computers use NAND gates.
C)
Any logic function can be realized by NAND gates alone
D)
All the minization techniques are applicable for optimum NAND gate realization

Correct Answer :   Any logic function can be realized by NAND gates alone

129 .
In Digital electronics (Boolean algebra), the OR operation is performed by which of the given properties
A)
Distributive properties
B)
Associative properties
C)
Commutative properties
D)
All of the above

Correct Answer :   All of the above

Explanation : In Boolean algebra, the distributive properties are given by the following equation:

A + BC = (A+B) (A+C) & A(B+C) = AB+AC


In Boolean algebra, the commutative properties are given by the following equation:

A+B = B+A & A*B = B*A


In Boolean algebra, the distributive properties are given by the following equation:

A+(B+C) = (A+B) +C & A*(B*C) = (A*B) *C

130 .
The Digital Electronics Queue is also known as___________
A)
FILO memory
B)
FIFO memory
C)
Flash memory
D)
None of the above

Correct Answer :   FIFO memory

Explanation : FIFO stands for First In - First Out. The queue is a type of memory based on FIFO, which means the request which has come first will be dealt with first. For example, the line of a crowd for booking railway tickets. The person who came first will get the ticket first. In the case of a Queue data structure, we call an ordinary queue as a FIFO queue.

131 .
In three-phase half-wave rectifier, each diode conducts for a duration of
A)
600
B)
900
C)
1200
D)
1800

Correct Answer :   1200

Explanation : Mainly, there are two types of 3 phase rectifiers: A half-wave rectifier and a full-wave rectifier. Many industries work on 3 phase power supply instead of a single phase. In three-phase half-wave rectifiers, each diode conducts for a duration of 120 0 because the cycle will be repeated itself, and each thyristor conducts for 1200 duration when the firing angle is less than 300.

132 .
DeMorgan's Law states that
A)
(AB)' = A' + B'
B)
(A+B)' = A'*B
C)
(AB)' = A + B
D)
(AB)' = A' + B

Correct Answer :   (AB)' = A' + B'

Explanation : DeMorgan's theorems play a vital role in digital electronics. It gives an equivalency between the logic gates. There are two distinct types of DeMorgan's theorems: the first gives the equivalent of the NAND gate, and the other gives the equivalent of the NOR gate. As per the dual property of DeMorgan's theorem (AB)' = A' + B' & (A+B) = A' * B'

133 .
The logical sum of two or more than two logical products is termed as
A)
SOP
B)
POS
C)
OR operation
D)
NAND operation

Correct Answer :   SOP

Explanation : SOP stands for "Sum of products." SOP is a way that a Boolean Algebra formula can be written. For example, the sum of product formula: AB + A'B'. In other words, it is defined as the logical sum of two or more logical product terms. POS refers to the logical product of two or more than two logical sum terms.

134 .
What is the group of 1s in 4 cells of a K – map called?
A)
Pair
B)
Octet
C)
Octave
D)
Quad

Correct Answer :   Quad

Explanation : A group of 1s in 4 cells of a K – map is called Quad. A group of 1s in 2 cells of a K – map is called Pair and a group of 1s in 8 cells of a K – map is called Octet.

135 .
What will be the frequency of the output from a JK flip – flop, when J = 1, K = 1, and a clock with pulse waveform is given?
A)
Twice the frequency of clock input
B)
Half the frequency of clock input
C)
Equal to the frequency of clock input
D)
Independent of the frequency of clock input

Correct Answer :   Half the frequency of clock input

Explanation : A single flip flop is a divide – by – two device. The frequency of the output from a JK flip – flop, when J = 1, K = 1, and a clock with pulse waveform is given is half the frequency of clock input.

136 .
What gate is placed between clock input and the input of AND gate to convert a positive level triggered flip – flop to a negative level triggered flip – flop?
A)
Buffer
B)
NOT gate
C)
NOR gate
D)
NAND gate

Correct Answer :   NOR gate

Explanation : The negative level triggered the flip – flop in Digital Electronics changes its state when the clock is negative. Thus, a negative level triggered flip – flop has a NOT gate present between clock input and the input of AND gate.

137 .
In Digital Circuits, which of the following options represent the synchronous control inputs in a T flip flop?
A)
0
B)
1
C)
T
D)
Clock

Correct Answer :   T

Explanation : The input at which the flip flop changes its state when synchronized with the clock is called the synchronous control inputs. For T flip flop T is the synchronous control input.

138 .
NAND. gates are preferred over others because these
A)
Can be used to make any gate
B)
have lower fabrication area
C)
consume least electronic power
D)
provide maximum density in a chip.

Correct Answer :   Can be used to make any gate

139 .
Which is the correct order of sequence for representing the input values in K-map?
A)
(00, 10, 01, 11)
B)
(00, 10, 11, 01)
C)
(00, 01, 10, 11)
D)
(00, 01, 11, 10)

Correct Answer :   (00, 01, 11, 10)

140 .
The inputs of a NAND gate are connected together. The resulting circuit is ___________.
A)
OR gate
B)
NOT gate
C)
AND gate
D)
None of the above

Correct Answer :   NOT gate

141 .
Digital computers are more widely used as compared to analog computers, because they are
A)
Less expensive
B)
Easier to maintain
C)
Always more accurate and faster
D)
Useful over wider ranges of problem types

Correct Answer :   Useful over wider ranges of problem types

142 .
A K-map (Karnaugh map) is an abstract form of which diagram organized as a squares matrix.
A)
Cycle diagram
B)
Block diagram
C)
Venn diagram
D)
Square diagram

Correct Answer :   Venn diagram

Explanation : K- Map, also known as Karnaugh map, refers to a pictorial representation of a truth table. It helps in minimizing variables of any Boolean expression. It is also an abstract form of a Venn diagram arranged as a square of a matrix, where each square represents a minterm or maxterm.

143 .
Which of the given device used in speed control of a DC motor?
A)
FET
B)
SCR
C)
PNP transistor
D)
NPN transistor

Correct Answer :   SCR

Explanation : SCR stands for silicon-controlled rectifiers. SCR is used in speed control DC motor. SCR is controlled by a variable resistor potentiometer. Many Industries use variable speed drives for industrial applications. For example, rolling mills, railway traction, etc.

144 .
One nibble is equal to how many bits
A)
2
B)
4
C)
8
D)
12

Correct Answer :   4

Explanation : In digital electronics, the smallest unit of storage consisting of either 0 or 1 is called a bit. The arrangement of such 4 bits is known as a nibble. The arrangement of such 8 bits is known as a byte.

145 .
Suppose the output of an XNOR gate is 1. Which of the given input combination is correct?
A)
A = 0, B = 0
B)
A = 0, B' = 1
C)
A = 0, B = 1
D)
A = 1, B = 1

Correct Answer :   A = 0, B = 0

Explanation : An XNOR refers to a digital logic gate with two or more inputs and one output that executes logical equality. The output of an XNOR gate is true either all of its inputs are true, or all of its inputs are false. When one of its inputs is false, and others are true, then the output is false. The output of the XNOR gate is given by the following equation.

AB + A'B,' For A = 0 AND B = 0 the output will be 1.

146 .
What will a TTL digital circuit possess due to the presence of a multi – emitter transistor?
A)
Smaller area
B)
Larger area
C)
Smaller resistance
D)
Larger resistance

Correct Answer :   Smaller area

Explanation : TTL circuit uses multi – emitter transistors. These transistors have a smaller area. As Capacitance is directly proportional to area, a smaller area leads to a lower capacitance.

147 .
How must the output of a gate act when it is LOW in a TTL circuit?
A)
Acts as a voltage source
B)
Acts as a current source
C)
Acts as a voltage sink
D)
Acts as a current sink

Correct Answer :   Acts as a current sink

Explanation : If the gate output is Low in a TTL digital circuit, the gate must be capable of sinking current drawn from the input of gates. Thus, the output must act as a current sink.

148 .
Which of the following gives the correct number of multiplexers required to build a 32 x 1 multiplexer?
A)
Two 8 x 1 mux
B)
Three 8 x 1 mux
C)
Two 16 x 1 mux
D)
Three 16 x 1 mux

Correct Answer :   Two 16 x 1 mux

Explanation : Two 16 x 1 mux will enable to give 32 inputs. The final output can be obtained after passing the output from each 16 x 1 mux through an OR gate. The select lines will help in selecting a particular output.

149 .
What must be the input given to "R" when SR flip – flop is converted to JK flip – flop?
A)
J.Q
B)
K.Q
C)
J.K.Q
D)
None of the above

Correct Answer :   K.Q

Explanation : In Digital Electronics, to convert SR flip – flop to JK flip – flop the “R” input in the SR flip – flop is given input “K” and “Q” through an AND gate. The truth table of SR flip – flop and JK flip – flop are combined to get the expression.

150 .
What minimum distance is required for a single error correction according to Hamming's analysis in Digital Electronics?
A)
1
B)
2
C)
3
D)
4

Correct Answer :   3

Explanation : According to Hamming’s analysis, a minimum distance of 3 is required for a single error correction. Hamming distance represents the number of bits that change from one code word to the other.

151 .
How many errors can the Digital Electronics parity method can find in a single word?
A)
Single error
B)
Double error
C)
Triple error
D)
Multiple errors

Correct Answer :   Single error

Explanation : The parity method can help in finding only single errors within a word. The double errors cannot be found as the parity of the bits does not change. If double errors need to be identified, the check – sum method can be used.

152 .
Consider the representation of six-bit numbers by two’s complement, one’s complement, or by sign and magnitude: In which representation is there overflow from the addition of the integers 011000 and 011000?
A)
Two’s complement only
B)
Sign and magnitude and one’s complement only
C)
Two’s complement and one’s complement only
D)
All three representations

Correct Answer :   All three representations

153 .
Excess-3 code is known as
A)
Algebraic code
B)
Weighted code
C)
Cyclic redundancy code
D)
Self-complementing code

Correct Answer :   Self-complementing code

154 .
The number 10000 would appear just immediately after
A)
FFFF (hex)
B)
1111 (binary)
C)
7777 (octal)
D)
All of the above

Correct Answer :   All of the above

155 .
The only function of NOT gate is to ___________.
A)
Stop signal
B)
Invert input signal
C)
Act as a universal gate
D)
None of the above

Correct Answer :   Invert input signal

156 .
In DTL, the logic gating function is performed by
A)
Inductor
B)
Transistor
C)
Diode
D)
Transformer

Correct Answer :   Diode

Explanation : DTL stands for Diode Transistor Logic, where the diode serves as the Input network, and the switching operation is performed by the transistor. DTL is a predecessor of TTL (Transistor-Transistor Logic). The logic functions can be performed using resistors for biasing, transistors to amplify and diodes to switch and isolate inputs, producing logic levels.

157 .
The AND operation is equivalent to
A)
Intersection
B)
Union
C)
Division
D)
Both (B) and (C)

Correct Answer :   Intersection

Explanation : AND operation is equivalent to Intersection. It means Y = A.B i.e. A AND B = A Intersection B. The output is 1, if and only if all the given inputs are 1.

158 .
TTL is a class of digital circuits built from
A)
Resistors only
B)
BJT (Bipolar Junction Transistors) only
C)
JEFT only
D)
Both (A) and (B)

Correct Answer :   Both (A) and (B)

Explanation : TTL stands for Transistor-Transistor logic. It is a class of type of digital circuits made up of bipolar junction transistors and resistors. BJT has two types of charge carriers: the first one is the electron and the holes. There are two types of BJTs: NPN and PNP. In TTL, resistors play a very short role, and both logic gating and amplifying functions are carried out by the transistors.

159 .
Which logic unit is the fastest of all the logic families?
A)
ECL
B)
DTL
C)
TTL
D)
CMOS

Correct Answer :   ECL

Explanation : ECL stands for Emitter Coupled Logic. It is the fastest of all the logic families because of its higher transmission rate.

In Emitter Coupled Logic,

    * The storage time is removed as the transistors are utilized in different amplifier mode and are never driven into saturation.
    * It is the fastest logic family and has the minimum propagation delay.

In CMOS logic,

    * Power dissipation is basically 10nw per gate, relying on the power supply voltage, output load etc.
    * The CMOS components are usually expensive, but CMOS technology is cost-efficient.
    * It has high input impedance.

In TTL,

    * Power dissipation is basically 10nw per gate.
    * Cost-efficient components.
    * The possibility of damage to the equipment is less from electrostatic charge as compared to CMOS.

160 .
Positive integers must be represented by
A)
Signed numbers
B)
Unsigned numbers
C)
Both (A) and (B)
D)
None of the above

Correct Answer :   Unsigned numbers

Explanation : The negative integers are represented by signed numbers on the extreme left side, whereas the positive integers are represented using unsigned numbers.

161 .
Which of these flip – flops cannot be used to construct a serial shift register?
A)
D – flip flop
B)
SR flip – flop
C)
T flip – flop
D)
JK flip – flop

Correct Answer :   T flip – flop

Explanation : SR, D, and JK flip flops can be used to construct a serial shift register. A T flip – flop gives the output 0 when input 1 is given and gives output 1 when input 0 is given. Thus, it cannot be used as a serial shift register.

162 .
Which of these options represent the other name of Inter – Integrated logic?
A)
High threshold logic
B)
Emitter – Coupled Logic
C)
Merged Transistor Logic
D)
Resistor – Transistor logic

Correct Answer :   Merged Transistor Logic

Explanation : Inter – Integrated circuits can be represented by IIC or I2C is also called the Merged Transistor Logic. They use n – p – n or p – n – p transistors to form IC’s.

163 .
Which of the following options is a Current – Mode logic used in Digital Circuits?
A)
ECL
B)
IIC
C)
TTL
D)
RTL

Correct Answer :   ECL

Explanation : Emitter coupled logic or ECL is a Current – Mode logic. While operating in active mode, they help in eliminating the turn – off delay of saturated transistors. ECL family has a higher switching speed and dissipates more power.

164 .
How many AND gates are required to construct a 4 – bit parallel multiplier if four 4 – bit parallel binary adders are given?
A)
Two 2 – input AND gates
B)
Four 2 – input AND gates
C)
Eight 2 – input AND gates
D)
Sixteen 2 – input AND gates

Correct Answer :   Sixteen 2 – input AND gates

Explanation : Four 4 – bit parallel binary adders along with 16 number of 2 – input AND gates will be required to construct a 4 – bit parallel multiplier. The AND gate helps in getting the partial products while the parallel – adder are used to add the partial products.

165 .
Which of the following gate is a two-level logic gate
A)
OR gate
B)
NAND gate
C)
NOT gate
D)
EXCLUSIVE OR gate

Correct Answer :   EXCLUSIVE OR gate

166 .
When an input signal 1 is applied to a NOT gate, the output is ___________.
A)
0
B)
1
C)
Either 0 & 1
D)
None of the above

Correct Answer :   0

167 .
Storage of 1 KB means the following number of bytes
A)
1000
B)
1024
C)
1064
D)
1099

Correct Answer :   1024

168 .
For a Mod 64 parallel counter we need
A)
6 flip flops
B)
6 flip flops and 2 AND gates
C)
6 flip flops and 4 AND gates
D)
None of the above

Correct Answer :   6 flip flops and 4 AND gates

Explanation : 26 = 64

So we need 6 flip-flops and (6 - 2) = 4 AND gates.

169 .
The number of select lines in a 16 : 1 multiplexer are
A)
4
B)
6
C)
8
D)
10

Correct Answer :   4

Explanation : 24 = 16

170 .
For a Mod-64 synchronous counter the number of flip flops and AND gates needed is
A)
4 and 6 respectively
B)
5 and 7 respectively
C)
6 and 4 respectively
D)
7 and 5 respectively

Correct Answer :   6 and 4 respectively

Explanation : 26 = 64 Hence 6 flip-flops. The number of AND gates is 6 - 2 = 4 see in the given figure

171 .
A 4 bit DAC gives an output of 4.5 V for input of 1001. If input is 0110, the output is
A)
4.5 V
B)
3.0 V
C)
2.0 V
D)
1.5 V

Correct Answer :   3.0 V

Explanation :

172 .
The Ward- Leonard system is used for controlling the speed of
A)
DC motors
B)
Universal motors
C)
Induction motors
D)
Three-phase AC motors

Correct Answer :   DC motors

Explanation : The Ward Leonard system was implemented and used to control the speed of DC shunt electric motors. Previously, it was quite convenient to obtain a variety of speeds and reversing for industrial applications. The system consisted of any prime mover, including an AC motor driving a DC shunt generator. The armature of the DC generator was directly connected to the shunt motor's armature to be controlled. The DC motor had its magnetic field continuously excited while that of the DC generator, the magnetic field could be controlled in intensity and direction. As the prime mover rotated, the field of the DC generator was adjusted as required, hence its armature current-controlled, this current would be adjusted in magnitude and direction, and this, being fed to the armature of the DC motor, would create a driving torque as it reacted with the continuously applied motor field.

173 .
When the PIV rating of a diode is exceeded
A)
The diode behaves like a thyristor.
B)
The diode behaves like a resistor.
C)
The diode is destroyed.
D)
The diode behaves like a tunnel diode.

Correct Answer :   The diode is destroyed.

Explanation : PIV stands for Peak Inverse Voltage. In other words, PIV is defined as the maximum voltage that can apply to a diode in the reverse direction. Applying higher voltage will cause the diode to destroy. Start conducting current in the normally "OFF" direction, which will damage the diode and often do things you don't like to your circuit. The exact details depend on the circuit design.

We usually select the PIV larger than the largest normal reverse operating voltage in our circuit. If you are making a full-wave rectifier for 220 Vac, you'd typically select a diode with a 240 or more PIV to give some "head room" and "safety factor" on the diode. The minimum should usually be selected like this: round-up from your designed or simulated reverse voltage to the next higher PIV for a diode family that gives you the current you require.

174 .
Which insulating layer is used in the fabrication of MOSFET?
A)
Silicon Nitride
B)
Copper sulphate
C)
Aluminum sulphate
D)
Silicon dioxide

Correct Answer :   Silicon dioxide

Explanation : A MOSFET is a field-effect transistor. It depends on the presence of an electric field to control the characteristics of the conductive channel. In the MOSFET, the gate is insulated from the substrate by a layer of silicon dioxide, which is basically glass. The charges accumulate on the gate to create the electric field instead of just having them flow out. So, while silicon is the main constituent of the conductive channel, a thin layer of silicon dioxide is used to insulate the gate.

175 .
CMOS technology used in?
A)
Microprocessor
B)
Digital logic
C)
Inverter
D)
Both (A) and (B)

Correct Answer :   Both (A) and (B)

Explanation : CMOS stands for Complimentary Metal Oxide Semiconductor. It is a type of (mostly) digital logic that uses a pair of complementary field-effect transistors to switch electric current. There are some analog CMOS devices; they are a lot less common. CMOS technology is used in many electronic devices like Microprocessor, Ram, Microcontroller, and other logic circuits. When the gate is ON, one transistor is on, and the other is off. When the gate is OFF, the first transistor is off, and the other is ON.

176 .
How many cycles of addition and shifting in a 4 – bit multiplier are required to perform multiplication using the shift method?
A)
1
B)
2
C)
4
D)
8

Correct Answer :   4

Explanation : In Digital Electronics, 4 cycles of addition and shifting in a 4 – bit multiplier are required to perform multiplication using the shift method. The multiplicand is copied as a partial product when multiplier bit is 1 and multiplicand is 0 when multiplier bit is 0.

177 .
Which of the following codes is a sequential code?
A)
8421 code
B)
5421 code
C)
2441 code
D)
2421 code

Correct Answer :   8421 code

Explanation : A sequential code is a code where each succeeding code is one binary number more than the preceding code. Thus, 8421 is a sequential code. Sequential codes are useful in manipulating mathematical data.

178 .
Which of these code pairs correctly represent Digital Electronics reflective codes?
A)
2421 and 8421
B)
2421 and 5211
C)
5421 and 2421
D)
5211 and 8421

Correct Answer :   2421 and 5211

Explanation : A reflexive code is the one where the code for 9 is the complement of code for 0, code for 8 is the complement of code for 1, and so on. Thus, 2421 and 5211 are reflexive codes.

179 .
Which of the following options correctly represent the characteristic of Excess – 3 code?
A)
It is a reflexive code but not a sequential code
B)
It is a reflexive as well as a sequential code
C)
It is a sequential code but not a reflexive code
D)
It is neither a reflexive code nor a sequential code

Correct Answer :   It is a reflexive as well as a sequential code

Explanation : A reflexive code is a code where the code for 9 is the complement of code for 0 and so on. A sequential code is a code where each succeeding code is one binary number more than the preceding code. Excess – 3 code satisfies both these properties.

180 .
The basic building blocks of the arithmetic logic unit in digital computers are known as
A)
Adders
B)
Attenuator
C)
Subtractors
D)
Demultiplexer

Correct Answer :   Adders

Explanation : The basic building blocks of the arithmetic unit in digital computers are known as adders. Adder is the Arithmetic mathematical function derived out of Logic gates. So, Adder always plays a major role in understanding Digital Electronics. The simplest but the most powerful application of logic gates is Adder. A full adder is similar to a half adder except that instead of 2 inputs and two outputs, there are now three inputs and two outputs. The inputs are carry-in (Cin), X, and Y. Your outputs remain the same, sum, and carry-out (Cout).

A half adder is typically only useful for "single digit" addition. A full adder implements the half Adder to link multiple full adders together to achieve higher orders of addition. Sixteen full adders in the group allow 16- bit addition.

181 .
The number of inputs in a half adder is?
A)
32
B)
16
C)
8
D)
2

Correct Answer :   2

Explanation : The total number of inputs in a half adder is 2. The half adder circuit has two inputs: P and Q, which add two input digits and generate a carry and sum. With the help of half Adder, we can design circuits capable of performing simple addition with the help of logic gates. An EXOR gate has two inputs and carries links to input EXOR gates. The output of the half added is also two, SUM and CARRY.

182 .
Why is a decoder used in digital electronics?
A)
It is used to divide address bus and data bus.
B)
To convert non coded information into a binary coded form.
C)
To convert coded information into a non-coded form.
D)
None of the above

Correct Answer :   To convert coded information into a non-coded form.

Explanation : Decoder is usually used to convert the coded information (BCD) into a non-coded form. In other words, decoders are defined as an electronic device that is used to convert digital signal to an analog signal. The decoders are used in many communication devices that are used to communicate between two devices. The decoder allows n number of inputs and generates 2n numbers of outputs. For example, if we give two inputs, four by two decoder will produce four outputs.

183 .
The result "X + XY = X" follows which of these laws?
A)
Duality law
B)
Consensus law
C)
Distributive law
D)
Absorption law

Correct Answer :   Absorption law

Explanation : The results “X + XY = X” and “X(X + Y) = X” follows the absorption law. The expression given can be written in the form X + XY = X(1 + Y). Any value – added with 1 will give 1 itself. Therefore 1 + Y = 1 and X + XY = X.

184 .
Which of the following points is not correct regarding an Ex – NOR gate in Digital Electronics?
A)
It is a buffer
B)
It is a one – bit comparator
C)
It is a one – bit inverter
D)
It is a universal gate

Correct Answer :   It is a one – bit comparator

Explanation : Ex – NOR gate is a one – bit comparator as the output for the gate is 1 if similar inputs are given to the gate and output is 0 if different inputs are given to the gate.

185 .
Which gate is called the anti – coincidence and coincidence gate respectively?
A)
OR and AND
B)
XOR and XNOR
C)
AND and OR
D)
XNOR and XOR

Correct Answer :   XOR and XNOR

Explanation : XNOR gate is called coincidence gate and gives 1 if similar inputs are given to the gate and output is 0 if different inputs are given to the gate. XOR gate is called anti – coincidence gate and gives 0 if similar inputs are given to the gate and output is 1 if different inputs are given to the gate.

186 .
How much input and output needed for demultiplexer?
A)
One input many outputs
B)
One input one output
C)
Many outputs to one input
D)
None of the above

Correct Answer :   One input many outputs

Explanation : A demultiplexer or DEMUX is a device that takes a single input line and routes it to one of several digital output lines. A demultiplexer of 2n outputs has n number of select lines, which are used to choose which output line send the input. A demultiplexer is also known as data distributor.

187 .
A register can be defined as
A)
The group of flip-flops for storing n bit of information
B)
The group of transistors for storing n- a bit of information
C)
The group of flip-flops for storing binary information
D)
The group of transistors for storing two bits of information

Correct Answer :   The group of flip-flops for storing binary information

Explanation : An electronic register refers to a form of memory that uses a group of flip-flops that is suitable for storing binary information, such as a byte (8 bits) of data. Each flip flop is a binary cell suitable for storing individual bits of a binary word. The length of the stored binary information depends on the number of flip-flops that make up the register. The information in a register can be transferred form one flip-flop to another flip-flop.

188 .
The primary difference between a counter and a register is
A)
A register has no specific sequence of states.
B)
A register counts data.
C)
A counter has no particular sequence of states.
D)
A counter has the capability to store n bit of information whereas a register has one bit.

Correct Answer :   A register has no specific sequence of states.

Explanation : The primary difference between a counter and a register is that register has no specific state sequence except in certain conditions.

A counter is a special case of a register while the register has the same clock. generally, the register can only be stored, loaded, or used for the stack or as the program counter. The counter does not need to have the same clock.

Advantages of Counter : It is used in frequency dividers, Code generators and Period and sequence generators.

Advantages of Register : To Produce Time delay, Simplify Combinational Logic and Convert Serial Data to Parallel Data

189 .
What frequency division of the pulsed clock signal can be obtained by connecting 4 flip – flops in cascade?
A)
2
B)
4
C)
8
D)
16

Correct Answer :   16

Explanation : In Digital Circuits, a frequency division of 2n of the pulsed clock signal can be obtained by connecting n flip – flops in cascade. Thus, for 4 flip – flops clock frequency can be divided by 16.

190 .

Which of the following options represent the correct reduction of XYZ + XYZ ?

A)
B)
YZ
C)
X + X
D)
2YZ

Correct Answer :   YZ

Explaination :

Using Boolean identities of Digital Electronics the expression XYZ + XYZ can be reduced. According to Complementarity identity X + X = 1. Thus, YZ + XYZ = (X + X)YZ = YZ.

191 .
Which of the following options are correct for a 4×1 multiplexer?
A)
It has one 3 – input AND gate
B)
It has four 3 – input AND gates
C)
It has one 3 – input AND gate
D)
It has four 2 – input AND gates

Correct Answer :   It has four 3 – input AND gates

Explanation : A 4 x 1 multiplexer has 2 select lines, 4 input lines, and 1 output line. AND gates are required to pass the inputs. Thus 4 AND gates will be used for each input. 3 – input AND gate is used, where 2 inputs come from each of the select lines and 1 input for the data.

192 .
Which of these pins will allow to activate and deactivate a multiplexer?
A)
Logic pin
B)
Preset pin
C)
Enable pin
D)
Selection pin

Correct Answer :   Enable pin

Explanation : An enable pin allows to activate and deactivate the multiplexer. When enable pin is 0, the output is obtained while when enable pin is 0, the multiplexer is disabled.

193 .
What determines the output from the combinational logic circuit in Digital Electronics?
A)
Input signals expected in future
B)
Input signals from the past condition
C)
Input signals at the present moment
D)
Input signals from both past and present

Correct Answer :   Input signals at the present moment

Explanation : The output in a combinational circuit depends on the mixture of input signals present at that moment. It is not determined by the past conditions. The output in a synchronous circuit depends on the mixture of input signals present at that moment and also the past conditions.

194 .
Dual slop ADC has the value of R = 1 K? and the value of C is 0.44 nano-farad has charging and discharging time for some specific voltage is nine ns and 3 ns, respectively. If the reference voltage is 4.4 V, what is the peak voltage reached by a triangular wave during the charging process?
A)
3 mV
B)
30 mV
C)
300 mV
D)
None of the above

Correct Answer :   30 mV

Explaination :

195 .
Which of the following characteristic are necessary for a sequential circuit?

1. It must have 6 gates
2. It must have feedback
3. Its output should depend on past value

Which of the above statements are correct?
A)
1, 2
B)
2, 3
C)
1, 3
D)
1, 2, 3

Correct Answer :   2, 3

196 .
A combination circuit is one in which the output depends on
A)
input combination at that time
B)
present output and previous output
C)
input combination and previous input
D)
input combination and previous output

Correct Answer :   input combination at that time

197 .
F's complement of (2BFD)hex is
A)
C 403
B)
E 304
C)
D 403
D)
D 402

Correct Answer :   D 402

Explaination :

198 .
The two-transistor model of the SCR is obtained by
A)
Bisecting the SCRs diagonally
B)
Bisecting the SCRs top two layers
C)
Bisecting the SCRs bottom two Layers
D)
Bisecting the SCRs top two and bottom two layers

Correct Answer :   Bisecting the SCRs top two and bottom two layers

Explanation : The two- transistor model of the SCR is obtained by bisecting the SCRs top two and bottom two layers. The two-transistor analogy of SCR refers to a method of producing an SCR as a combination of an np-n and a p-np transistor. SCR is a three-terminal device having a p-n-p-n structure. The three terminals of the junctions are the cathode, anode and gate terminal.

199 .
What is the main function of the filter in a rectifier circuit?
A)
To suppress odd harmonics.
B)
Remove ripples from the rectified output.
C)
Maximize AC input variations
D)
Minimize DC input and AC output variations.

Correct Answer :   Remove ripples from the rectified output.

Explanation : The main function of the filter in a rectifier circuit is to remove ripples from the rectified output. As we know, rectifiers are primarily used to convert alternating current (AC) to direct current (DC). There we find a considerable AC component in the output, which is called ripple.

Many electronic systems require pure direct current supply to drive or power them. To make a efficient continuous power supply that gives pure DC output, we need to remove the AC component from the output of rectifiers.

200 .
What is the actual meaning of the parallel load of a shift register?
A)
All flip-flops are present with data.
B)
All flip-flops are set with data.
C)
It means a parallel shifting of data.
D)
Each flip flop is loaded with data simultaneously.

Correct Answer :   All flip-flops are present with data.

Explanation : The actual meaning of the parallel load of a shift register is all flip-flops are present with data. It means that all of the register stages are loaded at a time with new data bits by a single load pulse. In the present condition, the outputs of flip flops will be 1. The value of Preset equals 1 means Q equals 1, this the value of the input is definitely 1.

201 .
A mode-10 counter can divide the clock frequency by a factor of
A)
10
B)
100
C)
1000
D)
10000

Correct Answer :   10

Explanation : Decade counter is divide by 10 counter.

202 .
Which of the following binary numbers is equivalent to decimal 10?
A)
1100
B)
1001
C)
1010
D)
1000

Correct Answer :   1010

Explanation : 1010 = 8 + 0 + 2 + 0 = 10.

203 .
What will be maximum input that can be converted for a 6 bit dual slope A/D converter uses a reference of -6v and a 1 MHz clock. It uses a fixed count of 40 (101000).
A)
10 V
B)
9.45 V
C)
9 V
D)
8 V

Correct Answer :   9.45 V

Explanation :

204 .
The number of digit 1 present in the binary representation of 3 x 512 + 7 x 64 + 5 x 8 + 3 is
A)
8
B)
9
C)
10
D)
12

Correct Answer :   9

Explaination :

3 x 512 + 7 x 64 + 5 x 8 + 3

= (2 + 1) x 29 + (4 + 2 + 1)26 + (4 + 1)23 + (2 + 1)

= 210 + 29 + 28 + 27 + 26 + 25 + 23 + 21 + 1

= 210 + 29 + 28 + 27 + 26 + 25 + 23 + 21 + 20


9 term of power two

Hence number of '1' is 9.

205 .
Out of 5 M x 8, 1 M x 16, 2 M x 16 and 3M x 8 memories, which memory can store more bits?
A)
1 M x 16
B)
2 M x 16
C)
3 M x 8
D)
5 M x 8

Correct Answer :   5 M x 8

Explaination : Bits are 40 M, 16 M and 32 M.

206 .
A ripple counter has 4 bits and uses flip flops with propagation delay time of 25 ns. The maximum possible time for change of state will be
A)
100 ns
B)
75 ns
C)
50 ns
D)
25 ns

Correct Answer :   100 ns

Explanation : In ripple counter all the delays are added.

207 .
A counter has a modulus of 10. The number of flip flops is
A)
3
B)
4
C)
5
D)
10

Correct Answer :   4

Explanation : 23 = 8 and 24 = 16 Therefore 4 flip-flops are needed. Some states will be skipped to give a modulus of 10.

208 .
In an 8085 microprocessor, the instruction CMP B has been executed while the content of the accumulator is less than that of register B, As a result.
A)
carry flag will be set but zero flag will be reset
B)
carry flag will be reset but zero flag will be set
C)
both carry flag and zero flag will be reset
D)
both carry flag and zero flag will be set

Correct Answer :   carry flag will be set but zero flag will be reset

209 .
Computers use thousands of flip-flops. To coordinate the overall action, a common signal is sent to all flip-flop known as
A)
active signal
B)
toggle signal
C)
debug signal
D)
clock signal

Correct Answer :   clock signal

210 .
A Schottky diode has_____
A)
no minority carriers and very high voltage drop in forward direction
B)
large number of minority carriers and very low voltage drop in forward direction
C)
no minority carriers and very low voltage drop in forward direction
D)
large number of minority carriers and very high voltage drop in forward direction

Correct Answer :   no minority carriers and very low voltage drop in forward direction

211 .
Boolean algebra obeys
A)
associative law
B)
distributive law
C)
commutative law
D)
commutative, associative and distributive law

Correct Answer :   commutative, associative and distributive law

212 .
The figure of merit for a logic family is
A)
gain band width product
B)
(propagation delay time) (power dissipation)
C)
(fan out) (power dissipation)
D)
(noise margin) (power dissipation)

Correct Answer :   (propagation delay time) (power dissipation)

213 .
A compiler is a software programme which
A)
executes the program
B)
assembles the program
C)
change the program into binary form
D)
change high level Programming language into low level machine language

Correct Answer :   change high level Programming language into low level machine language

214 .
In an 8 -bit Johnson counter sequence, how many states orbit patterns are possible?
A)
240
B)
232
C)
228
D)
210

Correct Answer :   240

Explanation :

As we know, the total number of states in the Jhonson counter is determined by the given formula

2N = 2 8= 256

Now,

the total number of used states = 2N = 2* 8 = 16

therefore, the total number of unused states = 256-16 = 240

215 .
If a transistor has IC = 110 mA and IE = 55 mA, find the value of β?
A)
1
B)
5
C)
7
D)
9

Correct Answer :   1

Explaination :

In common emitter, the term β stands for current gain. Current gain refers to the ratio between collector current and base current at a constant VCE.

β = IC/IB

In the common base, DC gain α refers to the ratio of the collector current IC and the emitter current IE.

The equation of dc current gain

α = IC/IE

Now, we can establish the relationship between α and β

β = α/ (1 - α)

Given

Emitter current IE = 55 mA

Collector current IC = 110 mA

α = IC/IE = 110/55 = 2

β = α/ (1 - α) = 2/ (1 - 2)

β = -2

Here the negative value of β indicates its direction, because by convention positive current is always termed as flowing into the device. So, the current gain is negative.

216 .
What are the three output conditions of 3- state buffer?
A)
Negative, positive, 0
B)
1, Low Impedance, float
C)
High, Low, float
D)
High Impedance, 0, float

Correct Answer :   High, Low, float

Explanation : The three or tri-state conditions of a three-state buffer are High, Low, and float. A three-state buffer refers to a state buffer that' output can be made high impedance in addition to high or low logic states. It is useful in a condition where you have more than one output on a given line. For example, a multi-drop communication bus. If the 3-state control input is 1, then output is electrically isolated/disconnected or floated. It is as if a very high impedance of 10 Megaohms is inserted between the output pin and internal circuit. Now output pin can be set to 0 or 1 by any other output signal connected to the output.

217 .
Decimal 1932 when converted into 10's complement will become
A)
8608
B)
8068
C)
8868
D)
8806

Correct Answer :   8068

218 .
While obtaining minimal SOP expression
A)
all do not care terms are ignored
B)
all do not care terms are treated as 0
C)
all do not care terms are treated as 1
D)
only such do not care terms which aid minimization are treated as 1

Correct Answer :   only such do not care terms which aid minimization are treated as 1

219 .
In 8085 microprocessor, how many interrupt control lines are there?
A)
6
B)
8
C)
12
D)
16

Correct Answer :   8

220 .
A is even or B is true. Negation of above statement is
A)
A is odd and B is false
B)
A is odd or B is false
C)
A is even or B is false
D)
A is even and B is false

Correct Answer :   A is odd and B is false

221 .
The abbreviation DTL stands for
A)
Digital Timing Logic
B)
Delayed Tracking Logic
C)
Diode Transistor Logic
D)
Dynamic Transient Logic

Correct Answer :   Diode Transistor Logic

222 .
In a 100 kHz clock frequency, 16 bits can be serially entered into a shift register?
A)
150 micro-sec
B)
160 micro-sec
C)
170 micro-sec
D)
180 micro-sec

Correct Answer :   160 micro-sec

Explanation :

f = 100 kHz

As we know, frequency ( f )= 1/T

So, T = (1/100) m sec

= 1/0.1 micro second = 10 micro sec; In serial transmission first the one- bit data enters at a time. After 16 clock cycles 16 bit will be loaded, it means = 16*10 = 160 micro-sec.

223 .
A series of equal space time pulses may be easily generated by which type of counter circuit?
A)
Binary shift
B)
Clock shift
C)
Johnson shift
D)
Ring counter

Correct Answer :   Ring counter

Explanation : A series of equally spaced timing pulses may be easily generated in clock shifts. In the Ring counter, the output of the last flip flops is connected to the first flip flop input, i.e., the ring counter is the cascaded connection of flip flops. It means feedback of the output of the flip-flops is fed to the input of the same flip-flop. It generates equally spaced timing pulses.

224 .
At which frequency the digital data can be applied to a gate?
A)
Operating frequency
B)
AC frequency
C)
Run-time frequency
D)
Propagation Frequency

Correct Answer :   Operating frequency

Explanation : The operating frequency refers to the frequency at which the communications are being made with the total bandwidth occupied by the carrier signal with modulation.

225 .
What is the purpose of using ALE signal high?
A)
To disable data bus latch
B)
To latch data D₀ - D₇ from bus to separate data bus
C)
Both (A) and (B)
D)
To latch low order address from bus to separate A₀ - A₇ lines

Correct Answer :   To latch low order address from bus to separate Aâ‚€ - A₇ lines

226 .
Assuming accumulator contain A 64 and the carry is set (1). What will register A and carry (CY) contain after ORA A?
A)
00 H, 0
B)
00 H, 1
C)
A 6 H, 0
D)
A 6 H, 1

Correct Answer :   A 6 H, 0

227 .
2's complement of a given 3 or more bit number of non-zero magnitude is the same as the original number if all bits except
A)
LSB are 1
B)
MSB are zero
C)
MSB are 1
D)
LSB are zero

Correct Answer :   MSB are zero

228 .
Which liquid crystal is used for LCD display?
A)
Mercury
B)
Aqua regia
C)
Liquid boron
D)
Pneumatic fluid

Correct Answer :   Pneumatic fluid

229 .
If interrupt service request have been received from all of the following interrupts, then which one will be serviced last?
A)
RST 5.5
B)
RST 6.5
C)
RST 7.5
D)
None of the above

Correct Answer :   RST 5.5

230 .
Two 16 : 1 and one 2 : 1 multiplexers can be connected to form a
A)
8 : 1 multiplexer
B)
16 : 1 multiplexer
C)
32 : 1 multiplexer
D)
64 : 1 multiplexer

Correct Answer :   32 : 1 multiplexer