Logic Gates

Q1: If a 3-input NOR gate has eight input possibilities, how many of those possibilities will result in a HIGH output?

A 1

B 2

C 7

D 8

Q2: If a signal passing through a gate is inhibited by sending a LOW into one of the inputs, and the output is HIGH, the gate is a(n):

A AND

B NAND

C NOR

D OR

Q3: A clock signal with a period of 1 s is applied to the input of an enable gate. The output must contain six pulses. How long must the enable pulse be active?

A Enable must be active for 0 s.

B Enable must be active for 3 s.

C Enable must be active for 6 s.

D Enable must be active for 12 s.

Q4: A 2-input NOR gate is equivalent to a ________.

A negative-OR gate

B negative-AND gate

C negative-NAND gate

D none of the above

Q5: The AND function can be used to ________ and the OR function can be used to ________ .

A enable, disable

B disable, enable

C enable or disable, enable or disable

D detect, invert

Q6: CMOS IC packages are available in ________.

A DIP configuration

B SOIC configuration

C DIP and SOIC configurations

D neither DIP nor SOIC configurations

Q7: How many input combinations would a truth table have for a six-input AND gate?

A 32

B 48

C 64

D 128

Q8: The switching speed of CMOS is now ________.

A competitive with TTL

B three times that of TTL

C slower than TTL

D twice that of TTL

Q9: The term "hex inverter" refers to:

A an inverter that has six inputs

B six inverters in a single package

C a six-input symbolic logic device

D an inverter that has a history of failure

Q10: The output of a NOT gate is HIGH when ________.

A the input is LOW

B the input is HIGH

C power is applied to the gate's IC

D power is removed from the gate's IC

Q11: Which of the following is not a basic Boolean operation?

A OR

B NOT

C AND

D FOR

Q12: If the input to a NOT gate is A and the output is X, then ________.

A X = A

B

C X = 0

D none of the above

Q13: How many truth table entries are necessary for a four-input circuit?

A 4

B 8

C 12

D 16

Q14: Which of the following choices meets the minimum requirement needed to create specialized waveforms that are used in digital control and sequencing circuits?

A basic gates, a clock oscillator, and a repetitive waveform generator

B basic gates, a clock oscillator, and a Johnson shift counter

C basic gates, a clock oscillator, and a DeMorgan pulse generator

D basic gates, a clock oscillator, a repetitive waveform generator, and a Johnson shift counter

Q15:
A logic probe is again applied to the pins of a 7421 IC with the following results. Is there a problem with the circuit and if so, what is the problem?

A Pin 6 should be ON.

B Pin 8 should be ON.

C Pin 8 should be pulsing.

D no problem

Q16: If a 3-input OR gate has eight input possibilities, how many of those possibilities will result in a HIGH output?

A 1

B 2

C 7

D 8

Q17: The Boolean expression for a 3-input OR gate is ________.

A X = A + B

B X = A + B + C

C X = ABC

D X = A + BC

Q18: The output of a NOR gate is HIGH if ________.

A all inputs are HIGH

B any input is HIGH

C any input is LOW

D all inputs are LOW

Q19: What is the circuit number of the IC that contains four two-input AND gates in standard TTL?

A 7402

B 7404

C 7408

D 7432

Q20: The basic types of programmable arrays are made up of ________.

A AND gates

B OR gates

C NAND and NOR gates

D AND gates and OR gates

Q21: The output of a NAND gate is LOW if ________.

A all inputs are LOW

B all inputs are HIGH

C any input is LOW

D any input is HIGH

Q22: The terms "low speed" and "high speed," applied to logic circuits, refer to the ________.

A rise time

B fall time

C propagation delay time

D clock speed

Q23: How many inputs of a four-input AND gate must be HIGH in order for the output of the logic gate to go HIGH?

A any one of the inputs

B any two of the inputs

C any three of the inputs

D all four inputs

Q24: A device used to display one or more digital signals so that they can be compared to expected timing diagrams for the signals is a:

A DMM

B spectrum analyzer

C logic analyzer

D frequency counter

Q25: When used with an IC, what does the term "QUAD" indicate?

A 2 circuits

B 4 circuits

C 6 circuits

D 8 circuits

Q26: If a 3-input AND gate has eight input possibilities, how many of those possibilities will result in a HIGH output?

A 1

B 2

C 7

D 8

Q27: How many inputs are on the logic gates of a 74HC21 IC?

A 1

B 2

C 3

D 4

Q28: One advantage TTL has over CMOS is that TTL is ________.

A less expensive

B not sensitive to electrostatic discharge

C faster

D more widely available

Q29: Which of the following logical operations is represented by the + sign in Boolean algebra?

A inversion

B AND

C OR

D complementation

Q30: What is the Boolean expression for a three-input AND gate?

A X = A + B + C

B
X = A · B · C
 

C A – B – C

D A $ B $ C

Q31: Which of the following gates is described by the expression ?

A OR

B AND

C NOR

D NAND

Q32: The output of an exclusive-NOR gate is HIGH if ________.

A the inputs are equal

B one input is HIGH, and the other input is LOW

C the inputs are unequal

D none of the above

Q33: The output of an AND gate with three inputs, A, B, and C, is HIGH when ________.

A A = 1, B = 1, C = 0

B A = 0, B = 0, C = 0

C A = 1, B = 1, C = 1

D A = 1, B = 0, C = 1

Q34: What is the difference between a 7400 and a 7411 IC?

A 7400 has two four-input NAND gates; 7411 has three three-input AND gates

B 7400 has four two-input NAND gates; 7411 has three three-input AND gates

C 7400 has two four-input AND gates; 7411 has three three-input NAND gates

D 7400 has four two-input AND gates; 7411 has three three-input NAND gates

Q35: The Boolean expression for a 3-input AND gate is ________.

A X = AB

B X = ABC

C X = A + B + C

D X = AB + C

Q36: The output of an OR gate with three inputs, A, B, and C, is LOW when ________.

A A = 0, B = 0, C = 0

B A = 0, B = 0, C = 1

C A = 0, B = 1, C = 1

D all of the above

Q37: What is the name of a digital circuit that produces several repetitive digital waveforms?

A an inverter

B an OR gate

C a Johnson shift counter

D an AND gate

Q38: What are the pin numbers of the outputs of the gates in a 7432 IC?

A 3, 6, 10, and 13

B 1, 4, 10, and 13

C 3, 6, 8, and 11

D 1, 4, 8, and 11

Q39: What is the Boolean expression for a four-input OR gate?

A Y = A + B + C + D

B Y = A· B · C · D

C Y = A – B – C – D

D Y = A $ B $ C $ D

Q40: With regard to an AND gate, which statement is true?

A An AND gate has two inputs and one output.

B An AND gate has two or more inputs and two outputs.

C If one input to a 2-input AND gate is HIGH, the output reflects the other input.

D A 2-input AND gate has eight input possibilities.

Q41: Fan-out is specified in terms of ________.

A voltage

B current

C wattage

D unit loads

Q42: The logic gate that will have HIGH or "1" at its output when any one (or more) of its inputs is HIGH is a(n):

A OR gate

B AND gate

C NOR gate

D NOT operation

Q43: The logic expression for a NOR gate is ________.

A

B

C

D

Q44: The format used to present the logic output for the various combinations of logic inputs to a gate is called a(n):

A Boolean constant

B Boolean variable

C truth table

D input logic function

Q45: Output will be a LOW for any case when one or more inputs are zero for a(n):

A OR gate

B NOT gate

C AND gate

D NOR gate

Q46: The basic logic gate whose output is the complement of the input is the:

A OR gate

B AND gate

C inverter

D comparator

Q47: How many entries would a truth table for a four-input NAND gate have?

A 2

B 8

C 16

D 32

Q48: TTL operates from a ________.

A 9-volt supply

B 3-volt supply

C 12-volt supply

D 5-volt supply

Q49: Logically, the output of a NOR gate would have the same Boolean expression as a(n):

A NAND gate immediately followed by an inverter

B OR gate immediately followed by an inverter

C AND gate immediately followed by an inverter

D NOR gate immediately followed by an inverter

Q50: Which of the following equations would accurately describe a four-input OR gate when A = 1, B = 1, C = 0, and D = 0?

A 1 + 1 + 0 + 0 = 01

B 1 + 1 + 0 + 0 = 1

C 1 + 1 + 0 + 0 = 0

D 1 + 1 + 0 + 0 = 00

Q51: The output of an exclusive-OR gate is HIGH if ________.

A all inputs are LOW

B all inputs are HIGH

C the inputs are unequal

D none of the above

Q52: When reading a Boolean expression, what does the word "NOT" indicate?

A the same as

B inversion

C high

D low

Q53: The power dissipation, PD, of a logic gate is the product of the ________.

A dc supply voltage and the peak current

B dc supply voltage and the average supply current

C ac supply voltage and the peak current

D ac supply voltage and the average supply current

Q54: What does the small bubble on the output of the NAND gate logic symbol mean?

A open collector output

B tristate

C The output is inverted.

D none of the above

Q55: Which of the following gates has the exact inverse output of the OR gate for all possible input combinations?

A NOR

B NOT

C NAND

D AND

Q56: Write the Boolean expression for an inverter logic gate with input C and output Y.

A Y = C

B Y = 

Q57: A CMOS IC operating from a 3-volt supply will consume ________.

A less power than a TTL IC

B more power than a TTL IC

C the same power as a TTL IC

D no power at all

Q58: From the truth table for a three-input NOR gate, what is the only condition of inputs AB, and C that will make the output X high?

A A = 1, B = 1, C = 1

B A = 1, B = 0, C = 0

C A = 0, B = 0, C = 1

D A = 0, B = 0, C = 0

Q59: A logic probe is placed on the output of a gate and the display indicator is dim. A pulser is used on each of the input terminals, but the output indication does not change. What is wrong?

A The dim indication on the logic probe indicates that the supply voltage is probably low.

B The output of the gate appears to be open.

C The dim indication is the result of a bad ground connection on the logic probe.

D The gate is a tristate device.

Q60:
A logic probe is used to test the pins of a 7411 IC with the following results. Is there a problem with the chip and if so, what is the problem?

A Pin 6 should be ON.

B Pin 6 should be pulsing.

C Pin 8 should be ON.

D no problem

Q61: How many AND gates are found in a 7411 IC?

A 1

B 2

C 3

D 4

Q62: If the output of a three-input AND gate must be a logic LOW, what must the condition of the inputs be?

A All inputs must be LOW.

B All inputs must be HIGH.

C At least one input must be LOW.

D At least one input must be HIGH.

Q63: How many pins does the 4049 IC have?

A 14

B 16

C 18

D 20

Q64: The NOR logic gate is the same as the operation of the ________ gate with an inverter connected to the output.

A OR

B AND

C NAND

D none of the above


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