In this article, we published the top 250 digital electronic circuits objective and answers for electrical and instrumentation engineers.
Digital Circuits Objective Questions
The below list provides all the multiple-choice questions (MCQ) related to digital circuits.
Answers are available at the bottom of the article.
1. Circuits made up of combinations of logic gates, with no feedback from outputs to inputs.
| A) | Latch |
| B) | Memory |
| C) | Combinational logic circuit |
| D) | Sequential logic circuit |
2. What digits are used in the binary number system?
| A) | all of the answers |
| B) | 0 and 1 |
| C) | high and low |
| D) | true and false |
3. Which of the following is a non-volatile device?
| A) | PLA |
| B) | RAM |
| C) | PLD |
| D) | ROM |
4. Which of the following does not form DACs?
| A) | Current switches |
| B) | Counter |
| C) | Resistor network |
| D) | Reference |
5. It is needed to translate a high-level program into a sequence of machine instructions that performs the desired task.
| A) | Assembler |
| B) | Compiler |
| C) | Debugger |
| D) | Interpreter |
6. Low-speed modems method of modulation is usually
| A) | amplitude modulation |
| B) | frequency-shift keying |
| C) | phase-shift modulation |
| D) | dibit modulation |
7. The number of input combinations will equal _____ for an N-input truth table.
| A) | 2N |
| B) | N |
| C) | 2N – 1 |
| D) | N-1 |
8. Quad 2-input XOR gates in the 7400 Family of TTL devices have a device number equivalent to
| A) | 7404 |
| B) | 7486 |
| C) | 7402 |
| D) | 7408 |
9. CMOS means
| A) | Complements Main-Oxidation Semiconductor |
| B) | Complementary Main-Oxide Semiconductor |
| C) | Correlation in Metal Oxidized Semiconductor |
| D) | Complementary Metal-Oxide Semiconductor |
10. The maximum deviation of DAC output from its ideal value, is expressed as a percentage of full scale.
| A) | Deviation ratio |
| B) | None of the answers |
| C) | Percentage error |
| D) | Full-scale error |
11. A counter that counts from a maximum count downward to zero
| A) | Up/down counter |
| B) | Synchronous counter |
| C) | Down counter |
| D) | Up counter |
12. How many different ways can we implement the inversion operation in a logic circuit?
| A) | One |
| B) | Two |
| C) | Four |
| D) | Three |
13. It is said to be a universal gate because any digital system can be implemented with it.
| A) | NAND |
| B) | OR |
| C) | AND |
| D) | Exclusive OR |
14. A system of coordinating I/O between the transmitting and receiving devices.
| A) | Handshaking |
| B) | Interfacing |
| C) | Charging |
| D) | Polling |
15. Use the expression for x = D + [(A+B)C]’ · E to determine the output of the circuit for the conditions A = B = E = 1, C = D = 0.
| A) | 1 |
| B) | 2 |
| C) | 10 |
| D) | 0 |
16. What is the normal resting state of the SET and CLEAR inputs in a flip-flop
| A) | High, low |
| B) | Low, low |
| C) | Low, high |
| D) | High, high |
17. A digital circuit that takes a 4-bit BCD input and activates the required outputs to display the equivalent decimal digit on a 7-segment display.
| A) | 7-segment display |
| B) | BCD-to-decimal decoder |
| C) | BCD-to-7-segment driver |
| D) | Decimal to BCD driver |
18. A technique often used to eliminate decoding spikes.
| A) | Tristate |
| B) | Strobing |
| C) | Wired-AND |
| D) | Wired-NAND |
19. The system program used to translate directly an assembly language to machine language is called
| A) | text editor |
| B) | compiler |
| C) | assembler |
| D) | debugger |
20. The Boolean expression for a six-input OR gate
| A) | U + V + W + X + Y + Z |
| B) | A · B · C · D · E · F |
| C) | A + B + C |
| D) | A + B + C + D + E + F |
21. A program which can be executed on several different computers to compare their speed and performance.
| A) | Diagnostic program |
| B) | Assembler |
| C) | Compiler |
| D) | Benchmark |
22. An electrical connection common to all segments of an LCD.
| A) | Cascade |
| B) | Backplane |
| C) | Bootstrap |
| D) | Dual slope |
23. The most widely used 7-bit alphanumeric code is the
| A) | Straight binary code |
| B) | Gray code |
| C) | ASCII |
| D) | EBCDIC |
24. A computer programming language in which groups of 1s and 0s are used to represent instructions.
It is also the only language a computer actually understood.
| A) | Programming language |
| B) | High – level language |
| C) | Machine language |
| D) | Application software |
25. What does a computer do with the data it receives from an ADC?
| A) | Processes the data |
| B) | Stores the data |
| C) | All of the answers |
| D) | Performs calculation |
26. A circuit made up of combinations of logic gates, with no feedback from output to input.
| A) | Combinational logic circuit |
| B) | Asynchronous circuit |
| C) | Sequential logic circuit |
| D) | Clocked circuits |
27. An unconnected input is termed as .
| A) | close |
| B) | floating |
| C) | open |
| D) | disconnected |
28. An RS flip-flop will not change in state when
| A) | R = 0, S = 1 |
| B) | R = 1, S = 0 |
| C) | R = 0, S = 0 |
| D) | R =1, S = 1 |
29. An IC that transforms parallel data to serial in the asynchronous format and vice versa.
| A) | USART |
| B) | UART |
| C) | MODEM |
| D) | RS232C |
30. From a 3-bit binary counter design using T flip-flops, determine the number of T flip- flops needed in its circuit implementation.
| A) | 1 |
| B) | 2 |
| C) | 4 |
| D) | 3 |
31. Another name for a decade counter
| A) | Binary counter |
| B) | frequency divider |
| C) | ripple shift counter |
| D) | BCD counter |
32. Meaning of checksum in ROM’s
| A) | regulates ROM |
| B) | It is a code placed in the last one or two ROM locations that represents the sum of the expected ROM data from all other locations. |
| C) | Used as a means to test for leakage in one or more ROM locations |
| D) | prevents decoding glitches |
33. Add 3AF to 23C
| A) | 101A |
| B) | 5EB |
| C) | BE5 |
| D) | A3B |
34. A binary counter that counts from 0000 to 1001 before it recycles.
| A) | Buffer |
| B) | Ring counter |
| C) | BCD counter |
| D) | Ripple counter |
35. A translated program in machine language is called
| A) | machine program |
| B) | an object program |
| C) | a source program |
| D) | users program |
36. A single bit comparator is usually implemented using
| A) | Exclusive OR |
| B) | NOR gate |
| C) | Exclusive NOR |
| D) | Wired-AND |
37. A state causing the flip-flop to change or reverse its state.
| A) | Reset |
| B) | Toggle |
| C) | Set |
| D) | Non-toggle |
38. The processor or central processing unit is
| A) | the heart of the computer |
| B) | communicates with the user |
| C) | employed RISC |
| D) | supports floating point numbers |
39. A digital circuit is also referred to as a/an _______ circuit.
| A) | sequential |
| B) | electrical |
| C) | logic |
| D) | arithmetic |
40. TTL, DTL, and ECL which are frequently used to refer to certain “families” of digital integrated circuits, are actually names of
| A) | companies that originated the families |
| B) | varieties of positive and negative logic |
| C) | general varieties of electronic circuits are used as logic gates, from which, in essence, the building blocks in each series are constructed. |
| D) | alternatives to positive and negative logic |
41. A type of computer bus which is bidirectional.
| A) | Data bus |
| B) | Calling bus |
| C) | Control bus |
| D) | Address |
42. A monostable multivibrator has
| A) | one stable state |
| B) | two stable states |
| C) | tristate |
| D) | no stable state |
43. An astable multivibrator has
| A) | no stable state |
| B) | tristate |
| C) | two stable states |
| D) | one stable state |
44. An instruction that causes data in the accumulator to be moved to the memory or a peripheral register.
| A) | LOOP |
| B) | FETCH |
| C) | LOAD |
| D) | STORE |
45. Which of the following is the language used in making an internet web page?
| A) | Hightech mark-up language |
| B) | Hypertext make-up language |
| C) | Highertext mark-up language |
| D) | Hypertext mark-up language |
46. A logic circuit that is triggered by a clock signal is
| A) | pulsed |
| B) | synchronous |
| C) | sequential |
| D) | Asynchronous |
47. What is the normal resting state of the SET and CLEAR inputs in a NAND gate latch?
| A) | SET = 0, CLEAR = 1 |
| B) | SET = 1, CLEAR = 0 |
| C) | SET = CLEAR = 0 |
| D) | SET = CLEAR = 1 |
48. An acceptable voltage range of logic 1 for TTL.
| A) | 2 to 5 V |
| B) | 3.5 to 5 V |
| C) | 0 to 0.8 V |
| D) | 0 to 1.5 V |
49. A result which is obtained when one is added to the least significant bit position of a binary number in the 1’s complement.
| A) | Spike |
| B) | 2’s complement form |
| C) | Signed binary numbers |
| D) | Complement |
50. The time difference which results when a clock may not arrive at all flip-flops at precisely the same time.
| A) | Glitch |
| B) | Clock skew |
| C) | Spike |
| D) | Hold |
51. A momentary, narrow, spurious, and sharply defined change in volume.
| A) | Clock |
| B) | Glitch |
| C) | Strobe |
| D) | Strobe |
52. In a computer system, it is a unit of hardware where the control keys are located.
| A) | I/O section |
| B) | Keyboard |
| C) | CPU |
| D) | Console |
53. That part of a computer instruction that defines what type of operation the computer is to execute on specified data.
| A) | Assembly language |
| B) | Mnemonic |
| C) | Op code |
| D) | Machine language |
54. What is the condition of the flip-flop when Q = 0 and Q = 1?
| A) | Preset |
| B) | Undetermined |
| C) | Reset |
| D) | Set |
55. A preproduction model of a system built for testing and debugging,
| A) | Prototype |
| B) | Maybe (colloquial) |
| C) | Wire list |
| D) | Sample |
56. Equivalent of decimal value of 178 in straight binary code is _____ and in BCD is .
| A) | 10110010, 101111000 |
| B) | 111111, 1100000 |
| C) | 11000, 11111111 |
| D) | 10111101, 100000 |
57. The data manipulated by a program is called _______ depending on its nature and extent.
| A) | data base |
| B) | input |
| C) | file |
| D) | all of the answers |
58. Which of the following involves digital quantities?
| A) | Current meter |
| B) | Ten position switch |
| C) | Temperature |
| D) | Radio volume control |
59. With OR operation, 1 + 1 =
| A) | 2 |
| B) | 1 |
| C) | 0 |
| D) | 10 |
60. What is the function of the comparator in the ADC?
| A) | Tells control logic when the DAC output exceeds the analog input |
| B) | Addition and multiplication |
| C) | Compares two parameters only |
| D) | Arithmetic operation |
61. A flip-flop which follows its input in the next state.
| A) | D |
| B) | JK |
| C) | T |
| D) | RS |
62. Typical propagation delay range for modern digital integrated circuits is
| A) | 1 to 100 microseconds |
| B) | 1 to 100 picoseconds |
| C) | 1 to 100 nanoseconds |
| D) | 1 to 100 milliseconds |
63. It is the required interval immediately following the active edge held of clocks during which the control inputs must be held.
| A) | Propagation time |
| B) | Hold time |
| C) | Pulsing time |
| D) | Set up time |
64. All arithmetic operations take place in the _______ of a computer
| A) | ROM |
| B) | CPU |
| C) | ALU |
| D) | Microprocessor |
65. What is the smallest type of computer in terms of their physical size?
| A) | Maxicomputer |
| B) | Mainframe |
| C) | Minicomputer |
| D) | Microcomputer |
66. An input that disables multiplexers or demultiplexers when it is HIGH.
| A) | Keyboard |
| B) | Decoder |
| C) | Strobe |
| D) | Binary input |
67. What graphical device is used to convert a truth table to its corresponding logic circuit in a simple and orderly process?
| A) | State table |
| B) | Truth table |
| C) | Karnaugh map |
| D) | State diagram |
68. In Boolean algebra, X + 1 =
| A) | X + 1 |
| B) | 0 |
| C) | 1 |
| D) | X |
69. Which of the following is not a dynamic test instrument?
| A) | Oscilloscope |
| B) | Logic monitor |
| C) | Logic analyzer |
| D) | Logic probe |
70. A circuit that produces an output pulse for a fixed period of time in response to a trigger and then returns to its quiescent state.
| A) | Astable circuit |
| B) | Monostable circuit |
| C) | Discriminator |
| D) | Bistable circuit |
71. What is the major advantage of serial transfer over parallel transfer?
| A) | one at a time transmission |
| B) | fewer interconnections between registers |
| C) | large interconnections between gates |
| D) | speed |
72. Application of excessive current to a fuse in order to open it.
| A) | Blowing |
| B) | Disconnecting |
| C) | Breaking |
| D) | Shorting |
73. What capital letter corresponds to 1000101 in the ASCII code?
| A) | A |
| B) | D |
| C) | E |
| D) | C |
74. A type of multivibrator circuit which generates a square wave of its own is the
| A) | flip-flop |
| B) | monostable |
| C) | bistable |
| D) | astable |
75. The flip-flop can change only when the appropriate clock transition occurs.
It is a condition called
| A) | latching |
| B) | clocking |
| C) | edge triggered |
| D) | pulsing |
76. How many AND gates and 4-bit binary adders are needed to implement a 2-bit to 3-bit binary multiplier?
| A) | 6 AND gates and one 4-bit binary adder |
| B) | 2 AND gates and one 4-bit binary adder |
| C) | 9 AND gates only |
| D) | 15 AND gates and three 4-bit binary adders |
77. Which of the following is a form of De Morgan’s theorem?
| A) | AB = (A + B)’ |
| B) | D. A·B = A’ · B’ |
| C) | (A + B)’ = A’ · B’ |
| D) | A + B = (AB)’ |
78. A circuit with no memory characteristic and whose output depends only on the current value of its inputs.
| A) | Boolean circuits |
| B) | Multiplexers |
| C) | CLC |
| D) | SLC |
79. Class of programmable logic devices wherein both its AND and its OR arrays are programmable.
| A) | Programmable Logic Controller |
| B) | Programmable Array Logic |
| C) | Field Programmable Logic Array |
| D) | Programmable Logic Circuit |
80. Simplify the expression y = AB’D + AB’D’.
| A) | AB’ |
| B) | AB |
| C) | BCD |
| D) | D’ |
81. The _____ belongs to a class of codes called the minimum-change codes, in which only one bit in the code group changes when going from one step to the next.
| A) | Gray code |
| B) | BCD code |
| C) | Morse code |
| D) | Excess-3 code |
82. What is the principal register of an arithmetic logic unit?
| A) | Controller |
| B) | Buffer |
| C) | Accumulator |
| D) | Actuator |
83. It represents machine instructions by mnemonic names and allows memory addresses and other constants to be represented by symbols rather than bit strings.
| A) | Assembly language |
| B) | Assembler |
| C) | Interpreter |
| D) | Machine language |
84. There are _____ flip-flops for a 3-bit binary counter.
| A) | 3 |
| B) | 4 |
| C) | 2 |
| D) | 5 |
85. Data retrieval from a memory is called
| A) | fetching |
| B) | accessing |
| C) | reading |
| D) | getting |
86. A command to an ADC to start conversion
| A) | EOC |
| B) | PAC |
| C) | SOC |
| D) | EAR |
87. If a certain circuit acts as AND gate when used with positive logic (H = 1, L = 0), what function will it perform when used with negative logic (H = 0, L = 1).
| A) | AND |
| B) | NOR |
| C) | OR |
| D) | NAND |
88. How many flip-flops are required for a counter that will count 0 to 255?
| A) | 16 |
| B) | 2 |
| C) | 8 |
| D) | 4 |
89. A T flip-flop can be derived by
| A) | by inverting the inputs of a JK flip-flop |
| B) | securing an integrated circuit with three inputs |
| C) | connecting the RS flip-flop’s input to ground |
| D) | connecting the two inputs of the JK flip-flop together |
90. A circuit that operates in such a way that its output is high when all its inputs are high.
| A) | OR |
| B) | AND |
| C) | NAND |
| D) | NOR |
91. It is the required interval immediately following the active edge of the clock signal during which the control inputs must be held stable.
| A) | All the time |
| B) | Set up time |
| C) | Pulsing time |
| D) | Hold time |
92. One of the standard levels of complexity of integrated circuits which contains 100,000 and more number of gates.
| A) | VLSI |
| B) | MSI |
| C) | SSI |
| D) | ULSI |
93. Duty cycle for repetitive waveform is defined as the
| A) | Sum of the ON time and the OFF time |
| B) | Ratio of the OFF time to the ON time |
| C) | Ratio of the ON time to the total time |
| D) | Ratio of the total time to the ON time |
94. Processors with more than two registers for arithmetic and logical operations are classified as
| A) | specific registered processors |
| B) | accumulator based |
| C) | serial register processor |
| D) | general register processors |
95. How many bits are in a byte?
| A) | 16 |
| B) | 4 |
| C) | 2 |
| D) | 8 |
96. In clock circuits, SWG means
| A) | standard wave ground |
| B) | square wave glitches |
| C) | square wave generators |
| D) | standard wire gauge |
97. An acceptable voltage range of a logic 0 for CMOS operating at VDD = 5 V.
| A) | 3.5 to 5 V |
| B) | 0 to 1.5 V |
| C) | 0 to 0.8 V |
| D) | 2 to 5 V |
98. Refer to the debugging method in which the program is executed one instruction at a time and the register contents can be examined after each step?
| A) | Syntax analyzing |
| B) | Semantic tracing |
| C) | Text editing |
| D) | Trace |
99. A digital circuit that produces an output code depending on which of its inputs is activated.
| A) | Encoder |
| B) | Demultiplexer |
| C) | Decoder |
| D) | Multiplexer |
100. The state of a flip-flop when Q = 0 and Q’ = 1
| A) | Set |
| B) | Reset |
| C) | Trigger state |
| D) | Tristate |
101. This bus carries lines that control the operation of the memory from the microprocessor to the memory.
| A) | Bus lines |
| B) | Address bus |
| C) | Data bus |
| D) | Control bus |
102. High-speed modems transmit between
| A) | 300 and 2400 bps. |
| B) | between 2400 and 9600 bps |
| C) | between 2400 and 9600 bps |
| D) | 2400 and 9600 bps |
103. A magnitude comparator has 22n entries in the truth table where n =
| A) | number of outputs |
| B) | number of inputs and outputs |
| C) | number of inputs |
| D) | number of comparator bits |
104. An acceptable voltage range of a logic 1 for CMOS operating at VDD = 5 V.
| A) | 3.5 to 5 V |
| B) | 2 to 5 V |
| C) | 0 to 0.8 V |
| D) | 0 to 1.5 V |
105. How many inputs does a full adder have?
| A) | 4 |
| B) | 3 |
| C) | 2 |
| D) | 8 |
106. Convert 1000 1001 0111 (BCD) to its decimal equivalent.
| A) | 798 |
| B) | 101 |
| C) | 457 |
| D) | 897 |
107. The output of an inverter is connected to the input of a second inverter. Determine the output level of the second inverter.
| A) | Undetermined state |
| B) | Output level is the same as the input level |
| C) | Output level is the complement of the input level |
| D) | High output is observed |
108. Perform binary subtraction to 6 ¼ and 4 ½ would result to
| A) | 1.00 |
| B) | 1.11 |
| C) | 10. 11 |
| D) | 1001. 01 |
109. An acceptable voltage range of a logic 0 for TTL.
| A) | 2 to 5 V |
| B) | 0 to 1.5 V |
| C) | 3.5 to 5 V |
| D) | 0 to 0.8 V |
110. An n-bit binary parallel adder requires ______ in its least design.
| A) | n half adders |
| B) | n half subtractor |
| C) | n half subtractor and n full adder |
| D) | n full adders |
111. A sequential logic circuit where the storage elements commonly used are time-delay devices (usually gates).
| A) | Asynchronous SLC |
| B) | Register |
| C) | Synchronous SLC |
| D) | Counter |
112. What is the output of an EX-OR gate when a logic signal and its exact inverse are connected to its input?
| A) | X |
| B) | 0 |
| C) | 1 |
| D) | X’ |
113. A small change made in resistance or capacitance to time a circuit precisely.
| A) | Bounce |
| B) | Tweaking |
| C) | Trigger |
| D) | Squeaking |
114. An equivalent Boolean equation for an exclusive NOR is
| A) | x’y + xy’ |
| B) | xy + xy’ |
| C) | xy + x’y’ |
| D) | xy’+ x’y’ |
115. When a flip-flop is set, what are the states of Q and Q’?
| A) | Q = 0, Q’ = 1 |
| B) | Q = 1, Q’ = 1 |
| C) | Q = 0, Q’ = 0 |
| D) | Q = 1, Q’ = 0 |
116. Asynchronous flip-flop input used to clear Q immediately to 0.
| A) | DC reset |
| B) | DC set |
| C) | DC clear |
| D) | DC toggle |
117. This occurs when the result of an arithmetic operation is a larger number than the output register can accommodate.
| A) | Underflow |
| B) | Overflow |
| C) | Lock-ahead carry |
| D) | Inflow |
118. In designing a 16 x 1 multiplexer, how many selection lines are needed?
| A) | 4 |
| B) | 32 |
| C) | 16 |
| D) | 2 |
119. What type of gate is equivalent to a NAND gate followed by an inverter?
| A) | NOR |
| B) | AND |
| C) | OR |
| D) | XOR |
120. A situation in a system where it can never leave or progress to another state.
| A) | Rest |
| B) | Toggle |
| C) | No change in state |
| D) | Hang-up state |
121. “Limbo” state of a flip-flop occurs when
| A) | both output are the same |
| B) | both outputs are low |
| C) | the outputs are inverse |
| D) | both outputs are high |
122. How many logic gates are in a VLSI chip?
| A) | 10,000 or more |
| B) | Anywhere from 100 to 9999 gates |
| C) | Between 12 to 99 gates |
| D) | Less than 12 gates |
123. Noise margin, which is one indication of how likely it is that information communicated between digital building blocks will be incorrect due to noise, depends on
| A) | output current capabilities and input current requirements |
| B) | the “safety margin” between the noise level and the noise figure. |
| C) | output power and required input power for the two logic states |
| D) | the “safety margin” between the output voltage produced by the transmitting block and input voltage required by the receiving block for each of the two-state. |
124. The most commonly used IC package for digital integrated circuits is the
| A) | CMOS pack |
| B) | Flat pack |
| C) | DIP ceramic |
| D) | DIP plastic |
125. This type of bus carries the memory address from the computer to the memory.
| A) | Address bus |
| B) | Parallel bus |
| C) | Control bus |
| D) | Data bus |
126. Why are voltage DAC’s generally slower than current DAC’s?
| A) | Because of its internal construction |
| B) | None of the answers |
| C) | Because of the response time of the op-amp current-to-voltage converter |
| D) | Because voltage DAC’s have many heat losses |
127. If F = XY + X’Y’ Boolean expression is to be implemented using decoders and OR gates, the connection involves
| A) | 2 to 4 line decoder with 1 OR gate |
| B) | 2 to 4 line decoder with 3 OR gates |
| C) | 3 to 8 line decoder with 2 OR gates |
| D) | 3 to 8 line decoder with 4 OR gates |
128. The triangle inside the rectangle which is part of the IEEE/ANSI symbol at clock input
| A) | all of the answers |
| B) | indicates triggering on a NGT |
| C) | indicates edge-triggered operation |
| D) | indicates the function of those inputs that are common to more than one circuit in the chip |
129. What is the hex equivalent of an ASCII code which means “HELP”?
| A) | 48 45 4C 50 |
| B) | 48 45 50 50 |
| C) | 58 57 58 48 |
| D) | 4C 50 51 52 |
130. A table used by a PLD language such as PALASM, to calculate the expected outputs for a set of inputs.
| A) | Truth table |
| B) | State table |
| C) | Excitation table |
| D) | Simulation table |
131. An input signal that can activate or disable a gate.
| A) | Wired-AND |
| B) | Strobe |
| C) | Tristate |
| D) | Glitch |
132. When power is first applied to any flip-flop circuit, it is impossible to predict the initial state of Q and Q’.
What could be done to ensure that NAND latch always started off in the Q = 1 state?
| A) | apply a momentary LOW to SET input |
| B) | apply a momentary HIGH to CLEAR input |
| C) | apply a momentary HIGH to PRESET input |
| D) | apply a momentary LOW to CLEAR input |
133. Arrival of a clock signal at the clock inputs of different flip-flops at different times as a result of propagation delays.
| A) | None of the answers |
| B) | Clock skew |
| C) | Buffer address |
| D) | Clock transition |
134. Which of the following does not describe a flip-flop?
| A) | It is a one-bit memory device. |
| B) | Its interval circuitry are usually symmetrical |
| C) | It is a bistable device |
| D) | It is equivalent to a one-shot circuit |
135. An area of memory that holds the ASCII characters that are being displayed on a monitor.
| A) | Space |
| B) | Start bit |
| C) | Terminal |
| D) | Screen image |
136. Which of the following does not describe a flip-flop circuit?
| A) | ROM |
| B) | Bistable multivibrator |
| C) | Memory |
| D) | Latch |
137. Text editors and formatters belong to the area of computing known as .
| A) | software |
| B) | word processing |
| C) | compilers |
| D) | assemblers |
138. The decimal system is composed of _____ numerals or symbols.
| A) | 2 |
| B) | 16 |
| C) | 8 |
| D) | 10 |
139. A term synonymous with CLEAR in computer systems.
| A) | Set |
| B) | Toggle |
| C) | Reset |
| D) | Load |
140. A property whereby the output of a digital-to-analog converter either increases or stays the same as the input is increased.
| A) | Monotonicity |
| B) | Immunity |
| C) | Parity |
| D) | Volatility |
141. A decoder with four inputs can have a maximum of how many outputs?
| A) | 8 |
| B) | 16 |
| C) | 32 |
| D) | 4 |
142. A programmable block of logic within a gate array, that contains a flip-flop for storage and also allows the user to specify logic functions on its inputs.
| A) | Configurable logic block |
| B) | PLD |
| C) | Block diagram |
| D) | Programmed block |
143. What binary number follows 1110?
| A) | 1000 |
| B) | 1010 |
| C) | 1111 |
| D) | 0111 |
144. Which type of flip-flop is best suited for synchronous transfer because it requires the fewest interconnections from one flip-flop to the other?
| A) | JK |
| B) | D |
| C) | T |
| D) | RS |
145. An analog memory output circuit used to eliminate aperture error is called a
| A) | DMUX |
| B) | MUX |
| C) | Flip-flop |
| D) | Track/store amplifier |
146. What will be the state of Q and Q’ after a flip-flop has been reset?
| A) | Q = 0, Q’ = 0 |
| B) | Q = 1, Q’ = 0 |
| C) | Q = 0, Q’ = 1 |
| D) | Q = 1, Q’ = 1 |
147. If each digit of a decimal number is represented by its binary equivalent, the result is a code called
| A) | Binary system |
| B) | Morse code |
| C) | Straight binary coding |
| D) | Binary-coded decimal |
148. The portion of an instruction cycle where the instruction is sent from memory to the instruction register
| A) | EXECUTE |
| B) | FETCH |
| C) | LOAD |
| D) | ACCUMULATE |
149. The state of the flip-flop after the occurrence of a clock pulse is called as its
| A) | current input |
| B) | next state |
| C) | present state |
| D) | current state |
150. The fastest method for transferring data from one register to another is the
| A) | serial transfer |
| B) | FIFO |
| C) | hybrid transfer |
| D) | parallel transfer |
151. An actuator in the DAC
| A) | controls a physical variable according to an electrical input signal |
| B) | performs conversion of digital data to its analog representation |
| C) | converts a non-electrical physical quantity to an electrical quantity |
| D) | performs calculation |
152. Which of the items below is not one of the three major sections of an MPU?
| A) | Timing and control |
| B) | Register |
| C) | Inversion |
| D) | ALU |
153. Speeds of modems are generally classified by the number of _____ they can transmit.
| A) | all of the answers |
| B) | bits per second |
| C) | cycles per second |
| D) | frequency per second |
154. Add the hex numbers 58 and 24.
| A) | 7C |
| B) | C7 |
| C) | 7D |
| D) | 2C |
155. What are the three basic parts of a BCD adder circuit?
| A) | Two connection logic and one 4-bit adder |
| B) | Two 4-bit adders and connection logic |
| C) | One connection logic and 4 full adders |
| D) | Two full adders and one AND gate |
156. A JK flip-flop will operate in the toggle mode when
| A) | J = 0, K = 1 |
| B) | J = 0, K = 0 |
| C) | J = 1, K = 0 |
| D) | J = 1, K = 1 |
157. Determine the sum-of-product expression for a circuit with four inputs and an output that is HIGH only when A is low at the same time that exactly two inputs are low.
| A) | A’B’C’ + A’C’D’ + A’B’D’ |
| B) | A’B’C’ + C’D’ |
| C) | 10 |
| D) | A’B’C’D + A’B’CD’ + A’BC’D’ |
158. What is meant by interfacing in a computer system?
| A) | Synchronization of digital information transmission between computer and external I/O devices |
| B) | Synchronization of data information operation in a computer |
| C) | Finding the fault in a network |
| D) | Connection of computers |
159. It consists of the instructions and data that the computer hardware manipulates to perform useful work.
| A) | Data |
| B) | File |
| C) | Software |
| D) | Program |
160. What is the binary ASCII code for a question mark?
| A) | 0100011 |
| B) | 0111000 |
| C) | 0111110 |
| D) | 0111111 |
161. What is the only input combination that will produce a high at the output of a five-input AND gate?
| A) | All inputs should be high |
| B) | All inputs should be low |
| C) | At least one high input |
| D) | At least one low input |
162. A register which holds the data being written into or read out of the addressed memory location.
| A) | Hold register |
| B) | Memory data register |
| C) | Glitch register |
| D) | Memory address register |
163. The most important memory element which is made of an assembly of logic gates is called
| A) | flip-flop |
| B) | all of the answers |
| C) | bistable multivibrator |
| D) | latch |
164. Instruction mnemonic means
| A) | representation of a quantity that varies in discrete steps |
| B) | a short abbreviation for the operation |
| C) | a binary code that represents the operation to be performed by the CPU |
| D) | technical term sometimes added to an IC’s description |
165. A term used to describe the logic function created when open-collector outputs are tied together.
| A) | Wired-AND |
| B) | Tristate |
| C) | Wired-OR |
| D) | Totem-pole |
166. What happens when the input to a digital IC is left unconnected for TTL ICs?
| A) | It becomes overheated |
| B) | It acts like logic 1 |
| C) | It eventually destroys itself. |
| D) | It acts just like logic 0 |
167. How does the operation of asynchronous input differ from that of a synchronous input?
| A) | it works independently of the clock input |
| B) | Not determined by ordinary operation |
| C) | it is mutually the same in function |
| D) | it is very dependent on the clock transition |
168. A counter that counts sequentially but does not step through all possible states, it returns to zero after a particular state.
| A) | Binary counter |
| B) | Decade counter |
| C) | Ripple counter |
| D) | Truncated counter |
169. A representation of numbers when negative numbers are obtained by complementing their positive equivalent and adding 1.
| A) | Signed numbers |
| B) | Indeterminate |
| C) | 2’s complement |
| D) | Inversion |
170. Add (74)8 with (1.1)2
| A) | (700)10 |
| B) | (10101.01)2 |
| C) | (75.4)8 |
| D) | (70.5)8 |
171. How many inputs does a half adder have?
| A) | 8 |
| B) | 4 |
| C) | 2 |
| D) | 1 |
172. Low-speed modems generally handle data rates between
| A) | 100 and 2400 bps |
| B) | 300 and 2400 bps |
| C) | 2400 and 9600 bps |
| D) | 3000 and 9000 bps |
173. An instruction that alters the normal course of a program by causing it to jump to another instruction.
| A) | ACC |
| B) | Jump |
| C) | Skip instruction |
| D) | Rotate instruction |
174. A digital circuit test equipment which is a troubleshooting tool that generates a short- duration pulse when activated manually, usually by pressing the button is the .
| A) | VOM |
| B) | logic clip |
| C) | logic pulser |
| D) | logic probe |
175. What device puts data on the data bus during a write operation?
| A) | ALU |
| B) | Keyboard |
| C) | CPU |
| D) | Accumulator |
176. What is the largest number that can be represented using 8 bits?
| A) | 10111111 |
| B) | 10111011 |
| C) | 111111111 |
| D) | 11011111 |
177. A square wave oscillator or clock generator
| A) | Astable circuit |
| B) | Debounding circuit |
| C) | Bistable circuit |
| D) | Monostable circuit |
178. Convert (614)8 to decimal.
| A) | 396 |
| B) | 392 |
| C) | 384 |
| D) | 400 |
179. How many bits are required to represent an eight digit decimal number in BCD?
| A) | 255 |
| B) | 256 |
| C) | 4 |
| D) | 32 |
180. What JK input condition will always set Q upon the occurrence of the active clock transition?
| A) | J = 0, K = 1 |
| B) | J = 1, K = 0 |
| C) | J = 0, K = 0 |
| D) | J = 1, K = 1 |
181. In BCD, the code 1111 is
| A) | 11 |
| B) | Invalid |
| C) | letter F |
| D) | A |
182. Class of programmable logic devices wherein its AND array is programmable while its OR array is hard-wired.
| A) | PROM |
| B) | PLA |
| C) | PLD |
| D) | PAL |
183. What is the decimal equivalent of (1101011)2?
| A) | 100 |
| B) | 108 |
| C) | 96 |
| D) | 107 |
184. Which of the following is NOT an advantage of state tables in sequential logic circuit design?
| A) | They result in synchronous circuit |
| B) | The number of variables is limited |
| C) | They minimize the gating required |
| D) | They are the systematic approach to a design problem |
185. Convert (B2F)16 to octal.
| A) | 7547 |
| B) | 11010 |
| C) | 5547 |
| D) | 5457 |
186. This occurs when the result of an arithmetic operation is a more negative number than the output register can accommodate.
| A) | Overflow |
| B) | None of the answers |
| C) | Error |
| D) | Underflow |
187. A computer language that enables Programmable Array Logic (PAL) users to generate a file that can be used to blow a PAL.
| A) | TURBO C++ |
| B) | Visual C |
| C) | JEDEC |
| D) | PALASM |
188. Data storage in a memory is termed as
| A) | loading |
| B) | reading |
| C) | memorizing |
| D) | writing |
189. A digital circuit that oscillates between two unstable output states.
| A) | Monostable multivibrator |
| B) | Astable multivibrator |
| C) | Flip-flop |
| D) | Bistable multivibrator |
190. A shift register in which the output of the last flip-flop is connected to the input of the first flip-flop.
| A) | BCD counter |
| B) | Ripple counter |
| C) | Parallel counter |
| D) | Ring counter |
191. The one-input RS flip-flop is the ______ flip-flop.
| A) | Latch |
| B) | T |
| C) | R |
| D) | D |
192. A circuit designed to produce a clean output in response to a switch closure.
| A) | Attenuator |
| B) | Debouncing circuit |
| C) | Filter circuit |
| D) | Monostable circuit |
193. How many flip-flops should be used to realize 32-count capacity?
| A) | 5 |
| B) | 4 |
| C) | 2 |
| D) | 6 |
194. An outstanding advantage of LCDs from LEDs.
| A) | LCDs essentially act as a capacitor and consume almost no power |
| B) | LCDs generates light |
| C) | LCDs are organized as a 7-segment display for numerical read out |
| D) | LCDs can be multiplexed |
195. The time it takes for the DAC output to settle to within ½ step size of its full scale value when the digital input changes from zero to full scale.
| A) | Settling time |
| B) | Full scale time |
| C) | Hold time |
| D) | Set-up time |
196. An IC that contains a large number of interconnected logic functions wherein the user can program the IC for a specific function by selectively breaking the appropriate interconnections.
| A) | PLD |
| B) | RAM |
| C) | ROM |
| D) | PLC |
197. What is an operand address?
| A) | The binary code that represents the operation to be performed by the CPU |
| B) | The address of the data to be operated as the CPU executes the instruction called for by the opcode |
| C) | All of the answers |
| D) | A short abbreviation for the operation |
198. The ______ operation result will be 1 if any one or more variables is a 1.
| A) | NOR |
| B) | NOT |
| C) | OR |
| D) | AND |
199. What is the next binary number following (10111)2 in the counting sequence?
| A) | 11100 |
| B) | 11001 |
| C) | 11000 |
| D) | 10110 |
200. A diagram consisting of a set of circles, where each circle contains a number of states within it.
| A) | State table |
| B) | Karnaugh map |
| C) | Transition diagram |
| D) | Bubble diagram |
201. The fan out capability of a digital building block depends on the current capability of its output and the current requirement of each input driven by that output, and maybe defined as the
| A) | maximum power dissipation that the unit can stand |
| B) | number of other inputs that can transmit to one input |
| C) | number of inputs that one output can transmit to |
| D) | amount of cooling required |
202. A ring counter where the output is inverted and tied back to the input
| A) | Decade counter |
| B) | Johnson counter |
| C) | BCD counter |
| D) | Shift counter |
203. A ______ takes the complete decimal number and represents it in binary.
| A) | BCD |
| B) | Straight binary code |
| C) | Excess-3 code |
| D) | Gray code |
204. A situation when a circuit’s output level for a given set of input conditions can be assigned as either
| A) | None of the answers |
| B) | 1 or a 0. |
| C) | Low level |
| D) | High level |
205. Correcting the faults in a circuit or a system.
| A) | Debugging |
| B) | Trap |
| C) | Fault corrector |
| D) | Buzz-out |
206. A one-input JK flip-flop is the ______ flip-flop.
| A) | S-R |
| B) | T |
| C) | C |
| D) | D |
207. A 20 KHz clock signal is applied to a JK flip-flop when J = 1, K = 1.
What is the frequency of the flip flop output waveform?
| A) | 40 KHz |
| B) | 20 KHz |
| C) | 10 KHz |
| D) | 5 KHz |
208. A block added to the combinational logic circuit to form a sequential logic circuit is the
| A) | counter |
| B) | clock |
| C) | memory |
| D) | ROM |
209. Given: x = A’BC (A+D)’.
Determine the output of the circuit x if A = 0, B = 1, C = 1 and D = 0.
| A) | 10 |
| B) | 0 |
| C) | 1 |
| D) | 2 |
210. A multiwire connection between digital circuits is usually called a
| A) | multiplexed line |
| B) | bus |
| C) | wire wrap |
| D) | ribbon |
211. How does a CMOS integrated circuit respond to a floating input?
| A) | Acts just like a logic 1 |
| B) | Open |
| C) | Shorted |
| D) | Unpredictable, may overheat and be destroyed |
212. A register which holds the address of the word currently being accessed.
| A) | Memory data register |
| B) | Access register |
| C) | Memory address register |
| D) | Hold register |
213. Class of mass memory devices that use a laser beam to write and read onto a specified coated disk.
| A) | RAM |
| B) | Mass storage |
| C) | Non-volatile memory |
| D) | Optical disk memory |
214. An instruction that causes data to be brought from memory into an accumulator register.
| A) | FETCH |
| B) | LOOP |
| C) | JUMP |
| D) | LOAD |
215. This type of fault has the same effect as an internal short between IC pins.
| A) | Broken wire |
| B) | Open signal lines |
| C) | Shorted signal lines |
| D) | Poor solder connections |
216. How many logic gates are in an MSI chip?
| A) | Less than 12 gates |
| B) | Anywhere from 100 to 9999 gates |
| C) | 10,000 or more |
| D) | Between 12 to 99 gates |
217. A ______ condition that exists if a circuit output depends on which of two nearly simultaneous inputs arrive at a point in the circuit first.
| A) | clear |
| B) | glitch |
| C) | race |
| D) | skew |
218. The state of the flip-flop before the occurrence of a clock pulse is called as its
| A) | current input |
| B) | present output |
| C) | present state |
| D) | next state |
219. The state of a flip=flop when Q = 1 and Q’ = 0.
| A) | Glitch |
| B) | Set |
| C) | Reset |
| D) | Latch |
220. An included input terminals in a magnitude comparator IC which is significant when both inputs compared are equal is called as its
| A) | input terminals |
| B) | setting |
| C) | cascading inputs |
| D) | address |
221. It converts a non-electrical physical quantity to an electrical quantity.
| A) | Transducer |
| B) | Converter |
| C) | Compiler |
| D) | Inverter |
222. How many logic gates are in an SSI chip?
| A) | 10,000 or more |
| B) | Less than 12 gates |
| C) | Between 12 to 99 gates |
| D) | Anywhere from 100 to 9999 gates |
223. A multiplexer is described by its size through _______, where n = number of bits.
| A) | 2n x m |
| B) | 1 x 2n |
| C) | n x 2n |
| D) | 2n x 1 |
224. Which of the items below can perform parallel-to-serial data conversion?
| A) | Decoder |
| B) | Binary counter |
| C) | Multiplexer |
| D) | Shift register |
225. In Boolean algebra, G + GF =
| A) | 1 |
| B) | GF |
| C) | F |
| D) | G |
226. In the 7400 Family of TTL Devices, Quad 2-input NAND gates has a device number equivalent to
| A) | 7486 |
| B) | 7402 |
| C) | 7432 |
| D) | 7400 |
227. In Boolean algebra, B · B’ =
| A) | B’ |
| B) | 0 |
| C) | 1 |
| D) | B |
228. How many outputs does a full adder have?
| A) | 8 |
| B) | 4 |
| C) | 2 |
| D) | 1 |
229. What is the largest decimal value that can be represented using 12 bits?
| A) | 4096 |
| B) | 4095 |
| C) | 2048 |
| D) | 144 |
230. What will be the states of Q and Q’ after a flip-flop has been cleared?
| A) | Q = 0, Q’ = 0 |
| B) | Q = 0, Q’ = 1 |
| C) | Q = 1, Q’ = 0 |
| D) | Q = 1. Q’ = 1 |
231. A bistable multivibrator has
| A) | no stable state |
| B) | one stable state |
| C) | two stable states |
| D) | tristate |
232. Which of the following items below is NOT one of the three basic operations of Boolean algebra?
| A) | Logical complementation |
| B) | Logical addition |
| C) | Logical subtraction |
| D) | Logical multiplication |
233. The number of digits used by a number system.
| A) | Base |
| B) | n |
| C) | Radix |
| D) | 2n |
234. Which of the following is NOT an internal digital IC fault?
| A) | Shorted signal lines |
| B) | Open signal lines |
| C) | Faulty power supply |
| D) | Poor solder connections |
235. The most primitive instructions that can be given to a computer are those interpreted directly by the hardware in ______ form.
| A) | machine language |
| B) | simulator |
| C) | assembly language |
| D) | high-level language |
236. Another name for a digital multiplexer is
| A) | compressor |
| B) | data selector |
| C) | decoder |
| D) | encoder |
237. A single word memory location used to temporarily hold data during program execution.
| A) | Accumulator |
| B) | Stack |
| C) | Register |
| D) | Buffer |
238. With a ________, a processor can store data at ay address and read back the stored information at any time.
| A) | RWM |
| B) | PLA |
| C) | ROM |
| D) | PROM |
239. What is the most common type of digital IC package?
| A) | DIP |
| B) | CMOS |
| C) | Metal type |
| D) | TTL |
240. In the data sheet of a digital building block, operating speed is typically expressed in terms of
| A) | transition frequency |
| B) | capacitance C |
| C) | propagation delay times for both possible output transitions |
| D) | miles per hour or centimeters per second |
241. A JK flip-flop can be made to function like a T flip-flop by simply
| A) | connecting the J and K inputs together as one input |
| B) | connecting earth ground the JK inputs |
| C) | connecting J = 0 and K = 0 |
| D) | resetting all inputs of the JK |
242. Change in state is
| A) | toggle |
| B) | reset |
| C) | same state |
| D) | set |
243. Small circles on the input or output lines of logic circuit symbols which represent inversion of a particular signal.
| A) | Bubble |
| B) | Clode |
| C) | Bootstrap |
| D) | Strobe |
244. A circuit that goes through 2n-1 states in a random fashion.
| A) | Pseudo-random sequence generator |
| B) | Counting shift |
| C) | Random generator |
| D) | Register |
245. BCD code has always ________ bits per number.
| A) | 2 |
| B) | 8 |
| C) | 16 |
| D) | 4 |
246. A logic circuit that depends on the status of its selected inputs will channel its data input to one of several data outputs.
| A) | MUX |
| B) | DMUX |
| C) | ROM |
| D) | RAM |
247. Which of the following choices is NOT a characteristic of analog quantity?
| A) | One quantity is represented by another which is proportional to the first |
| B) | Is considered discrete |
| C) | Variable amplitude |
| D) | They can vary over a continuous range of values |
248. Which of the following items below is not a part of the hardware organization in a computer?
| A) | Hardware realization |
| B) | Implementation |
| C) | Architecture |
| D) | Assembler |
249. An abbreviation that represents the opcode of a computer instruction.
| A) | Instruction |
| B) | ASCII |
| C) | Mnemonic |
| D) | Octets |
250. What two types of inputs that a clocked flip-flop has?
| A) | all of the answers |
| B) | synchronous control inputs and clock input |
| C) | Asynchronous control inputs and clock input |
| D) | Pulsed control inputs and clock input |
Click Here for Answers
If you liked this article, then please subscribe to our YouTube Channel for Electrical, Electronics, Instrumentation, PLC, and SCADA video tutorials.
You can also follow us on Facebook and Twitter to receive daily updates.
Next Quiz:
- Electronic Devices & Circuits Quiz
- Fundamentals of Digital Systems Quiz
- Network Theorems Objective Questions
- Digital Electronics Objective Questions
- Electrical Circuits Objective Questions