Digital Electronics Test 2016 – Upwork Test Answers

Till 27 February 2016, this Upwork Digital Electronics Test attended by 6,734 freelancers and total 2,431 freelancers qualified it. Please Try to review each questions and answers properly. Take your time. Maybe you can have Top Result in Upwork Digital Electronics Test.

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Upwork Digital Electronics Test 2016

2 Answered Test Questions:
1. 9’s complement of 56 is _____.
Answers:
a. 87
a. 49
a. 43
a. 35
2. The outputs Q and ¯Q of a master-slave S-R F/F are connected to its S and R inputs respectively. Its output Q, when clock pulses are applied, will be__________.
Answers:
a. permanently 0
a. permanently 1
a. fixed 0 and 1
a. complementary with every clock pulse

67 NOT Answered Yet Test Questions:
(hold on, will be updated soon)
3. Triggering action can be obtained in a J-K F/F by __________ .
Answers:
a. joining J and K points to ground
a. joining J point to Q and K to ¯Q
a. joining J and K points to positive supply
a. adding EX-OR gates at the output
4. Shifting the contents of a shift register one place to the left is equivalent to
Answers:
a. dividing the content by 10
a. dividing the content by 2
a. multiplying the content by 2
a. None of above
5. The write-cycle time of a memory is 200 nsec. The maximum rate at which data can be stored is________ .
Answers:
a. 200 words/sec
a. 5*103 words/sec
a. 5*106 words/sec
a. 5*107 words/sec
6. The most important advantage of CMOS is its _____.
Answers:
a. noise immunity
a. input impedance
a. low power consumption
a. output impedance
7. The number of 4-line-to-16-line decoders required to make an 8-line-to-250-line decoder is_____ .
Answers:
a. 16
a. 17
a. 32
a. 64
8. When a large number of analog-signals are to be converted to the digital form, the most suitable ADC is _________ converter.
Answers:
a. a forward-counter type
a. an up/down counter
a. a simultaneous type ADC
a. a successive approximation type
9. A twisted ring counter consisting of 6 F/F will have
Answers:
a. 6 states
a. 12 states
a. 64 states
a. 128 states
10. In BCD to 7 segment decoder/driver, the input is 1000. The segments which will be lit are _____.
Answers:
a. none
a. all segments
a. 2 segments
a. 4 segments
11. The race-around condition occurs in J-K F/F when____________ .
Answers:
a. both the inputs are 0
a. both the inputs are 1
a. the inputs are complementary
a. any of the above input combinations is present
12. A multiplexer having 32 data input lines needs _____ select lines.
Answers:
a. 5
a. 4
a. 3
a. 6
13. One OR gate can work as a _____ comparator.
Answers:
a. two-bit
a. three-bit
a. one-bit
a. four-bit
14. What would be the value of X if (110001)2= X10?
Answers:
a. 72
a. 50
a. 49
a. 12
15. A universal register _____.
Answers:
a. accepts serial input
a. accepts parallel input
a. gives serial and parallel outputs
a. is capable of all the above
16. If an ADC with 8-bit output gives full-scale deflection for 12v analog-signal, its resolution is _____.
Answers:
a. 8/12 v
a. 8*12 mv
a. 8/256 v
a. 12/256 v
17. The counting sequence of a uniform counter is 000,001,011,111,110,100.The counter is a _____.
Answers:
a. ripple binary counter
a. combination counter
a. ring counter
a. Johnson counter
18. A half adder consists of an _____ gate and a _____ gate.
Answers:
a. OR, NOR
a. OR, XOR
a. AND, XOR
a. NOT, XOR
19. In the BCD number system, subtraction is done by the______ method.
Answers:
a. 10’s complement
a. 2’s complement
a. 1’s complement
a. 9’s complement
20. The time taken by an ADC to perform a conversion is usually referred to as
Answers:
a. speed
a. propogation- delay
a. response- time
21. For a flip-flop with provisions of preset and clear__________.
Answers:
a. preset and clear operations are preferred simultaneously
a. while preseting, clear is disabled
a. while clearing, preset is disabled
a. both b and c
22. In an XNOR gate, input A is high and B is low. The output will _____.
Answers:
a. be low
a. be high
a. switch between low and high
a. None of the above
23. The design of a sequential circuit requires the use of _____.
Answers:
a. K-maps
a. state table/state diagram
a. Quine McCluskey method
a. None of the above
24. If in a clocked R-S F/F, point R is joined to point S through an inverter, the circuit will become a___________ .
Answers:
a. J-K F/F
a. T F/F
a. D F/F
a. None of the above
25. Which family has the fastest speed?
Answers:
a. TTL
a. ECL
a. CMOS
a. DTL
26. A monostable circuit gives a pulse-width output having tp=0.3 Rx.Cx. The device employed is likely to be_____ .
Answers:
a. 74121
a. 74122
a. 74221
a. 555-timer
27. If in a clocked R-S Flip Flop, point R is joined to point S through an inverter, the circuit will become a___________ .
Answers:
a. J-K Flip Flop
a. T Flip Flop
a. D Flip Flop
a. None of the above
28. A 4-bit synchronous counter uses flip-flops with the propagation delay time of 25nsec each. The maximum possible time required for the change of state will be _____.
Answers:
a. 100 nsec
a. 25 nsec
a. 50 nsec
a. 75 nsec
29. Which of the following memories uses an index-hole to provide timing signals?
Answers:
a. A magnetic tape
a. A charged coupled device
a. A floppy disk
a. None of the above
30. If inverters are added to the inputs of AND gate, the logic function is _____.
Answers:
a. OR
a. NOR
a. AND
a. EX-OR
31. In a microprocessor, the adder circuit is a part of
Answers:
a. instruction register
a. memory
a. ROM
a. ALU
32. A multiplexer tree is needed when the number of inputs is more than _____.
Answers:
a. 12
a. 16
a. 32
a. 64
33. A monostable circuit uses a timing register of 10k ohms and a capacitor of 0.1µF capacity respectively. Its pulse-width will be approximately_____ .
Answers:
a. 0.7 ms
a. 1 ms
a. 0.7 sec
a. 1 sec
34. Semi-conductor memories are widely used because of their__________ .
Answers:
a. small size
a. low cost.
a. compatibility with microprocessors
a. All of the above
35. A transparent latch consists of a__________ .
Answers:
a. T-type F/F
a. D-type F/F
a. T or D type F/F
a. T and d type F/F
36. One of the two states of a circuit is stable and the others are quasi-stable. The circuit is a _____ circuit.
Answers:
a. flip-flop
a. one-shot
a. bi-stable multivibrator(MVR)
a. free-running MVR
37. A semi-conductor ROM is basically a ________.
Answers:
a. combinational circuit
a. sequential circuit
a. set of flip-flops memory elements
a. None of the above
38. The minimum number of resistors required in a 4-bit network of weighted resistor type DAC is ______.
Answers:
a. 4
a. 8
a. 15
a. 16
39. The address bus width of a memory of size (1024*8) bit is _____.
Answers:
a. 8 bits
a. 10 bits
a. 12 bits
a. 16 bits
40. Decimal counters using flip flops and feedback are more popular than a decimal counter of ring counter type because of _____.
Answers:
a. simple decade circuitry required
a. economy in the number of flip flops
a. high speed of operation
a. its availability in IC form
41. Two mod-3 counters are cascaded. The circuit will behave as a _____.
Answers:
a. mod-3 counter
a. mod-6 counter
a. mod-9 counter
a. None of the above
42. Hexadecimal equivalent of (268)10 is_______ .
Answers:
a. (10 C)16
a. (9 C)16
a. (8 B)16
a. (7 E)16
43. How many memory locations can 14 address bits access?
Answers:
a. 64,382
a. 16,384
a. 1024
a. 2,048
44. Race condition occurs in _____.
Answers:
a. a combinational circuit
a. all the digital circuits
a. a synchronous circuit
a. an asynchronous circuit
45. The addition of hexadecimal number DF16 + AC16
Answers:
a. 11C16
a. 18B16
a. 15B16
a. 19E16
46. Shift-registers most commonly use _____.
Answers:
a. D F/F
a. R-S F/F
a. J-K F/F
a. T F/F
47. A 1 us pulse can be converted into a 1 ms pulse by using a _____ multivibrator(MVR).
Answers:
a. monostable
a. Schmitt-trigger
a. latch
a. free-running MVR
48. For a 12-bit ADC, the range of input-voltage is (0 to +10v).The voltage corresponding to LSB is _____.
Answers:
a. 0
a. 0.0012 v
a. 0.0024v
a. 0.833v
49. Pocket calculators use the_________ system.
Answers:
a. BCD
a. Exess-3
a. gray code
a. binary
50. A memory device that contains a SRAM and EEPROM in the same chip is called _____.
Answers:
a. EAPROM
a. EEPROM
a. NVRAM
a. DRAM
51. A flip-flop may be built with
Answers:
a. NAND gates
a. AND gates
a. OR gates
a. Any one of the above
52. A triggerable one-shot monostable MVR _____.
Answers:
a. can be triggered in the ON as well as quiescent state
a. can be triggered only in the quiescent state
a. can be triggered only in the ON state
a. does not require any triggering
53. The boolean expression xy + xz +xyz ( xy + z ) is equal to _____.
Answers:
a. 0
a. x
a. y
a. 1
a. x(y+z)
54. In a 4-bit weighted-register DAC, the resistor value corresponding to MSB is 2k ohm. The resistor value corresponding to LSB will be _____.
Answers:
a. 1 k ohm
a. 2 k ohm
a. 4 k ohm
a. 16 k ohm
55. In the floating point system, the exponent is written in __________ notation.
Answers:
a. gray code
a. hexadecimal
a. octal
a. excess-32
56. A PLA consists of
Answers:
a. AND matrrix
a. OR matrix
a. invert/non-invert matrix
a. All of these
57. In a shift register, complemented output point Ā of the last flip-flop is joined to point J of the first flip-flop while its point K is joined to point A of the last flip-flop. The circuit will work as _____.
Answers:
a. a shift count
a. a shift register
a. a ring counter
a. None of the above
58. A memory in which the contents get erased when power-failure occurs is called_______ .
Answers:
a. RAM
a. EAROM
a. PROM
a. ROM
59. While designing a counter circuit, the preferred type of flip-flop is _____.
Answers:
a. D-type
a. R-S F/F
a. J-K F/F
a. latch
60. A circuit has an output that is determined by the present input as well as the previous output states. The circuit is known as _____.
Answers:
a. a mealy machine
a. a moore machine
a. a sequential circuit
a. None of above
61. A J-K F/F may be obtained by adding__________ .
Answers:
a. AND gates to a clocked R-S F/F
a. OR gates to a D F/F
a. NAND gates to a T F/F
a. NAND gates to a R-S F/F
62. Adding inverters to the input of an OR gate produces the _____ logic function.
Answers:
a. NOR
a. AND
a. NAND
a. EX-OR
63. The most suitable gate for comparing two bits is the _____ gate.
Answers:
a. AND
a. EX-OR
a. OR
a. NAND
64. In an IC-555-timer, the load can be connected _____.
Answers:
a. only between the output terminal and the ground (GND)
a. only between the output terminal and the VCC
a. between the VCC and the GND
a. between either the output terminal and the GND or between the output terminal and the VCC
65. LSI and VLSI devices use the _____ technology.
Answers:
a. TTL
a. ECL
a. MOS
a. RCL
66. The boolean expression XY+X+XY is equal to _____.
Answers:
a. 1
a. 0
a. x
a. y
67. The comparison time of ADC-0800 is in the range of _____.
Answers:
a. a few tens of msec
a. a few tens of millions of msec
a. a few milli-secs
a. a few micro-secs
68. In sequential circuits, memory elements are _____.
Answers:
a. astable
a. monostable
a. bistable
a. tristate flip-flops
69. In a karnaugh map, a quad eliminates _____ variables.
Answers:
a. 4
a. 2
a. 8
a. 1

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