What is the defining difference between microprocessor/DSP systems and other digital systems?

The microprocessor follows a programmed sequence of instructions that the designer specified.

The digital system follows a programmed sequence of instructions that the designer specified.

The microprocessor follows a programmed sequence of instructions that the designer specified.

The microprocessor/DSP is faster.

The problem of the VOH(min) of a TTL IC being too low to drive a CMOS circuit and meet the CMOS requirement of VIH(min) is usually easily overcome by:

adding a fixed voltage-divider bias resistive network at the output of the TTL device

avoiding this condition and only using TTL to drive TTL

adding an external pull-down resistor to ground

adding an external pull-up resistor to

Why have PLDs taken over so much of the market?

One PLD does the work of many ICs.

Why are the maximum value of VOL and the minimum value of VOH used to determine the noise margin rather than the typical values for these parameters?

These are worst-case conditions.

These are best-case conditions.

It doesn't matter what values are used.

What does ECL stand for?

It stands for energy-coupled logic; the input energy is amplified by the input transistors and allows the device to deliver higher output currents.

It stands for electron-coupled logic; all of the devices used within the gates are N-type transistors.

It stands for emitter-coupled logic; all of the inputs are coupled into the device through the emitters of the input transistors.

It stands for emitter-coupled logic; all of the emitters of the input transistors are connected together and each transistor functions as an emitter follower.

It stands for energy-coupled logic; the input energy is amplified by the input transistors and allows the device to deliver higher output currents.

Which of the following summarizes the important features of emitter-coupled logic (ECL)?

good noise immunity, negative logic, high-frequency capability, low power dissipation, and short propagation time

low noise margin, low output voltage swing, negative voltage operation, fast, and high power consumption

good noise immunity, negative logic, high-frequency capability, low power dissipation, and short propagation time

low propagation time, high-frequency response, low power consumption, and high output voltage swings

poor noise immunity, positive supply voltage operation, good low-frequency operation, and low power

The high input impedance of MOSFETs:

reduces input current and power dissipation

Why is a pull-up resistor needed when connecting TTL logic to CMOS logic?

to decrease the output HIGH voltage

to increase the output LOW voltage

to decrease the output LOW voltage

to increase the output HIGH voltage

to decrease the output HIGH voltage

The word "interfacing" as applied to digital electronics usually means:

any gate that is a TTL operational amplifier designed to condition signals between NMOS transistors

a conditioning circuit connected between a standard TTL NAND gate and a standard TTL OR gate

a circuit connected between the driver and load to condition a signal so that it is compatible with the load

any gate that is a TTL operational amplifier designed to condition signals between NMOS transistors

any TTL circuit that is an input buffer stage

What is unique about TTL devices such as the 74S00?

The gate transistors are silicon (S), and the gates therefore have lower values of leakage current.

The S denotes the fact that a single gate is present in the IC rather than the usual package of 2 6 gates.

The S denotes a slow version of the device, which is a consequence of its higher power rating.

The devices use Schottky transistors and diodes to prevent them from going into saturation; this results in faster turn on and turn off times, which translates into higher frequency operation.

Refer to the figure given below. What type of device is shown and what input levels are required to turn the LED off?

The device is a Schottky AND gate and requires only one low input to turn the LED off.

The device is an open-collector AND gate and requires both inputs to be HIGH in order to turn the LED off.

The device is a Schottky AND gate and requires only one low input to turn the LED off.

The device is an open-collector AND gate and requires only one low input to turn the LED off.

The device is a Schottky open-collector AND gate and requires a low on both inputs to turn the LED off.

The bipolar TTL logic family that was developed to increase switching speed by preventing transistor saturation is:

transistor-transistor logic (TTL).

emitter-coupled logic (ECL) and transistor-transistor logic (TTL).

What type of circuit is shown below and which statement best describes its operation?

It is a hybrid TTL-CMOS inverter with FET totem-pole output.

It is a two-input CMOS AND gate with open drain.

It is a two-input CMOS buffer with tristate output.

It is a CMOS inverter with tristate output.

It is a hybrid TTL-CMOS inverter with FET totem-pole output.

What must be done to interface CMOS to TTL?

A 5 V Zener diode must be placed across the inputs of the TTL gates in order to protect them from the higher output voltages of the CMOS gates.

A dropping resistor must be used on the CMOS 12 V supply to reduce it to 5 V for the TTL.

As long as the CMOS supply voltage is 5 V, they can be interfaced; however, the fan-out of the CMOS is limited to two TTL gates.

A 5 V Zener diode must be placed across the inputs of the TTL gates in order to protect them from the higher output voltages of the CMOS gates.

The two series cannot be interfaced without the use of special interface buffers designed for that purpose, such as the open-collector buffers.

What type of circuit is represented in the given figure, and which statement best describes its operation?

It is a programmable inverter. It can be programmed to function as either an active LOW or an active HIGH inverter.

It is a tristate inverter. When the ENABLE input is HIGH, the output is effectively an open circuit it is neither LOW nor HIGH.

It is a programmable inverter. It can be programmed to function as either an active LOW or an active HIGH inverter.

It is an active LOW buffer, which can be turned on and off by the ENABLE input.

Which of the following summarizes the important features of ECL?

Good noise immunity, negative logic, high frequency capability, low power dissipation, and short propagation time

Low noise margin, low output voltage swing, negative voltage operation, fast, and high power consumption

Good noise immunity, negative logic, high frequency capability, low power dissipation, and short propagation time

Slow propagation time, high frequency response, low power consumption, and high output voltage swings

Poor noise immunity, positive supply voltage operation, good low frequency operation, and low power

Which of the following statements accurately represents the two BEST methods of logic circuit simplification?

Karnaugh mapping and circuit waveform analysis

Boolean algebra and Karnaugh mapping

Karnaugh mapping and circuit waveform analysis

Actual circuit trial and error evaluation and waveform analysis

Boolean algebra and actual circuit trial and error evaluation

Which of the following statements apply to CMOS devices?

The devices should not be inserted into circuits with the power on.

All tools, test equipment, and metal workbenches should be tied to earth ground.

The devices should be stored and shipped in antistatic tubes or conductive foam.

What causes low-power Schottky TTL to use less power than the 74XX series TTL?

The Schottky-clamped transistor

Nothing. The 74XX series uses less power.

What are the major differences between the 5400 and 7400 series of ICs?

The 7400 series are an improvement over the original 5400s.

The 5400 series are military grade and require tighter supply voltages and temperatures.

The 5400 series are military grade and allow for a wider range of supply voltages and temperatures.

The 7400 series are an improvement over the original 5400s.

The 7400 series was originally developed by Texas Instruments. The 5400 series was brought out by National Semiconductors after TI's patents expired, as a second supply source.

2291 + Mcqs in Digital Electronics in Engineering Page 6 McqOptions

251.	Which logic family is characterized by a multiemitter transistor on the input?
A.	ECL
B.	CMOS
C.	TTL
D.	None of the above
Answer» D. None of the above

252.	What is the defining difference between microprocessor/DSP systems and other digital systems?
A.	The digital system follows a programmed sequence of instructions that the designer specified.
B.	The microprocessor follows a programmed sequence of instructions that the designer specified.
C.	The digital system is faster.
D.	The microprocessor/DSP is faster.
Answer» B. The microprocessor follows a programmed sequence of instructions that the designer specified.

253.	The final step in the device programming sequence is ________.
A.	compiling
B.	downloading
C.	simulation
D.	synthesis
Answer» C. simulation

254.	Most look-up tables in field-programmable gate arrays (FGPAs) use ________ inputs, resulting in ________ possible outputs.
A.	4,16
B.	8,16
C.	4,12
D.	6,12
Answer» B. 8,16

255.	The problem of the V_OH(min) of a TTL IC being too low to drive a CMOS circuit and meet the CMOS requirement of V_IH(min) is usually easily overcome by:
A.	adding a fixed voltage-divider bias resistive network at the output of the TTL device
B.	avoiding this condition and only using TTL to drive TTL
C.	adding an external pull-down resistor to ground
D.	adding an external pull-up resistor to
E.	<i>V<sub>CC</sub></i>
Answer» E. <i>V<sub>CC</sub></i>

256.	A look-up table is simply a truth table with all the possible output connections listed with their desired input response.
A.	True
B.	False
Answer» C.

257.	Why have PLDs taken over so much of the market?
A.	One PLD does the work of many ICs.
B.	The PLDs are cheaper.
C.	Less power is required.
D.	All of the above
Answer» E.

258.	What is the advantage of using low-power Schottky (LS) over standard TTL logic?
A.	more power dissipation
B.	less power dissipation
C.	cost is less
D.	cost is more
Answer» C. cost is less

259.	Why are the maximum value of V_OL and the minimum value of V_OH used to determine the noise margin rather than the typical values for these parameters?
A.	These are worst-case conditions.
B.	These are normal conditions.
C.	These are best-case conditions.
D.	It doesn't matter what values are used.
Answer» B. These are normal conditions.

260.	A TTL totem-pole circuit is designed so that the output transistors:
A.	are always on together
B.	provide linear phase splitting
C.	provide voltage regulation
D.	are never on together
Answer» E.

261.	The most common TTL series ICs are:
A.	E-MOSFET
B.	7400
C.	quad
D.	AC00
Answer» C. quad

269.	The IEEE/ANSI notation of an internal underlined diamond denotes:
A.	totem-pole outputs.
B.	open-collector outputs.
C.	quadrature amplifiers.
D.	tristate buffers.
Answer» C. quadrature amplifiers.

271.	Generally, the voltage measured at an unused TTL input would typically be measured between:
A.	1.4 to 1.8 V.
B.	0 to 5 V.
C.	0 to 1.8 V.
D.	0.8 to 5 V.
Answer» B. 0 to 5 V.

274.	The rise time (t_r) is the time it takes for a pulse to rise from its ________ point up to its ________ point. The fall time (t_f) is the length of time it takes to fall from the ________ to the ________ point.
A.	10%, 90%, 90%, 10%
B.	90%, 10%, 10%, 90%
C.	20%, 80%, 80%, 20%
D.	10%, 70.7%, 70.7%, 10%
Answer» B. 90%, 10%, 10%, 90%

278.	What is the static charge that can be stored by your body as you walk across a carpet?
A.	300 volts
B.	3,000 volts
C.	30,000 volts
D.	Over 30,000 volts
Answer» E.

262.	What does ECL stand for?
A.	It stands for electron-coupled logic; all of the devices used within the gates are N-type transistors.
B.	It stands for emitter-coupled logic; all of the inputs are coupled into the device through the emitters of the input transistors.
C.	It stands for emitter-coupled logic; all of the emitters of the input transistors are connected together and each transistor functions as an emitter follower.
D.	It stands for energy-coupled logic; the input energy is amplified by the input transistors and allows the device to deliver higher output currents.
Answer» D. It stands for energy-coupled logic; the input energy is amplified by the input transistors and allows the device to deliver higher output currents.

263.	Which of the following summarizes the important features of emitter-coupled logic (ECL)?
A.	low noise margin, low output voltage swing, negative voltage operation, fast, and high power consumption
B.	good noise immunity, negative logic, high-frequency capability, low power dissipation, and short propagation time
C.	low propagation time, high-frequency response, low power consumption, and high output voltage swings
D.	poor noise immunity, positive supply voltage operation, good low-frequency operation, and low power
Answer» B. good noise immunity, negative logic, high-frequency capability, low power dissipation, and short propagation time

264.	The high input impedance of MOSFETs:
A.	allows faster switching
B.	reduces input current and power dissipation
C.	prevents dense packing
D.	creates low-noise reactions
Answer» C. prevents dense packing

265.	Why is a pull-up resistor needed when connecting TTL logic to CMOS logic?
A.	to increase the output LOW voltage
B.	to decrease the output LOW voltage
C.	to increase the output HIGH voltage
D.	to decrease the output HIGH voltage
Answer» D. to decrease the output HIGH voltage

266.	The time needed for an output to change from the result of an input change is known as:
A.	noise immunity
B.	fan-out
C.	propagation delay
D.	rise time
Answer» D. rise time

267.	The word "interfacing" as applied to digital electronics usually means:
A.	a conditioning circuit connected between a standard TTL NAND gate and a standard TTL OR gate
B.	a circuit connected between the driver and load to condition a signal so that it is compatible with the load
C.	any gate that is a TTL operational amplifier designed to condition signals between NMOS transistors
D.	any TTL circuit that is an input buffer stage
Answer» C. any gate that is a TTL operational amplifier designed to condition signals between NMOS transistors

268.	What is unique about TTL devices such as the 74S00?
A.	The gate transistors are silicon (S), and the gates therefore have lower values of leakage current.
B.	The S denotes the fact that a single gate is present in the IC rather than the usual package of 2 6 gates.
C.	The S denotes a slow version of the device, which is a consequence of its higher power rating.
D.	The devices use Schottky transistors and diodes to prevent them from going into saturation; this results in faster turn on and turn off times, which translates into higher frequency operation.
Answer» E.

270.	Refer to the figure given below. What type of device is shown and what input levels are required to turn the LED off?
A.	The device is an open-collector AND gate and requires both inputs to be HIGH in order to turn the LED off.
B.	The device is a Schottky AND gate and requires only one low input to turn the LED off.
C.	The device is an open-collector AND gate and requires only one low input to turn the LED off.
D.	The device is a Schottky open-collector AND gate and requires a low on both inputs to turn the LED off.
Answer» B. The device is a Schottky AND gate and requires only one low input to turn the LED off.

272.	The bipolar TTL logic family that was developed to increase switching speed by preventing transistor saturation is:
A.	emitter-coupled logic (ECL).
B.	current-mode logic (CML).
C.	transistor-transistor logic (TTL).
D.	emitter-coupled logic (ECL) and transistor-transistor logic (TTL).
Answer» E.

273.	What type of circuit is shown below and which statement best describes its operation?
A.	It is a two-input CMOS AND gate with open drain.
B.	It is a two-input CMOS buffer with tristate output.
C.	It is a CMOS inverter with tristate output.
D.	It is a hybrid TTL-CMOS inverter with FET totem-pole output.
Answer» D. It is a hybrid TTL-CMOS inverter with FET totem-pole output.

Explore topic-wise MCQs in Engineering.

Which logic family is characterized by a multiemitter transistor on the input?

What is the defining difference between microprocessor/DSP systems and other digital systems?

The final step in the device programming sequence is ________.

Most look-up tables in field-programmable gate arrays (FGPAs) use ________ inputs, resulting in ________ possible outputs.

The problem of the VOH(min) of a TTL IC being too low to drive a CMOS circuit and meet the CMOS requirement of VIH(min) is usually easily overcome by:

A look-up table is simply a truth table with all the possible output connections listed with their desired input response.

Why have PLDs taken over so much of the market?

What is the advantage of using low-power Schottky (LS) over standard TTL logic?

Why are the maximum value of VOL and the minimum value of VOH used to determine the noise margin rather than the typical values for these parameters?

A TTL totem-pole circuit is designed so that the output transistors:

The most common TTL series ICs are:

What does ECL stand for?

Which of the following summarizes the important features of emitter-coupled logic (ECL)?

The high input impedance of MOSFETs:

Why is a pull-up resistor needed when connecting TTL logic to CMOS logic?

The time needed for an output to change from the result of an input change is known as:

The word "interfacing" as applied to digital electronics usually means:

What is unique about TTL devices such as the 74S00?

The IEEE/ANSI notation of an internal underlined diamond denotes:

Refer to the figure given below. What type of device is shown and what input levels are required to turn the LED off?

Generally, the voltage measured at an unused TTL input would typically be measured between:

The bipolar TTL logic family that was developed to increase switching speed by preventing transistor saturation is:

What type of circuit is shown below and which statement best describes its operation?

The rise time (tr) is the time it takes for a pulse to rise from its ________ point up to its ________ point. The fall time (tf) is the length of time it takes to fall from the ________ to the ________ point.

Cascade chains are closely associated with ________.

What is the increase in switching speed between 74LS series TTL and 74HC/HCT (High-Speed CMOS)?

What must be done to interface CMOS to TTL?

What is the static charge that can be stored by your body as you walk across a carpet?

The simplest equation which implements the K-map shown below is:

What type of circuit is represented in the given figure, and which statement best describes its operation?

Which of the following logic families has the highest noise margin?

How many 1-of-16 decoders are required for decoding a 7-bit binary number?

Which of the following logic expressions represents the logic diagram shown?

Which of the following summarizes the important features of ECL?

A 74HC147 priority encoder has ten active-LOW inputs and four active-LOW outputs. What would be the state of the four outputs if inputs 4 and 5 are LOW and all other inputs are HIGH?

A(n) ________ consists of a programmable array of AND gates that connects to a fixed array of OR gates and is usually OTP.

When did the first PLD appear?

SPLDs, CPLDs, and FPGAs are all which type of device?

Which of the figures in figure (a to d) is equivalent to figure (e)?

Convert BCD 0001 0111 to binary.

How many data select lines are required for selecting eight inputs?

Convert BCD 0001 0010 0110 to binary.

Which of the following statements accurately represents the two BEST methods of logic circuit simplification?

The implementation of simplified sum-of-products expressions may be easily implemented into actual logic circuits using all universal ________ gates with little or no increase in circuit complexity. (Select the response for the blank space that will BEST make the statement true.)

Which of the following statements apply to CMOS devices?

What causes low-power Schottky TTL to use less power than the 74XX series TTL?

What are the major differences between the 5400 and 7400 series of ICs?

What type of logic circuit is shown below and what logic function is being performed? >

Which of the logic families listed below allows the highest operating frequency?

Refer to the given figure. What type of output arrangement is being used for the output?

Most look-up tables in field-programmable gate arrays (FGPAs) use inputs, resulting in possible outputs.

The problem of the V_OH(min) of a TTL IC being too low to drive a CMOS circuit and meet the CMOS requirement of V_IH(min) is usually easily overcome by:

Why are the maximum value of V_OL and the minimum value of V_OH used to determine the noise margin rather than the typical values for these parameters?

The rise time (t_r) is the time it takes for a pulse to rise from its point up to its point. The fall time (t_f) is the length of time it takes to fall from the to the point.

275.	Cascade chains are closely associated with ________.
A.	CLBs
B.	SOP functions
C.	logic expansion
D.	all of the above
Answer» E.

276.	What is the increase in switching speed between 74LS series TTL and 74HC/HCT (High-Speed CMOS)?
A.	5
B.	10
C.	50
D.	100
Answer» C. 50

277.	What must be done to interface CMOS to TTL?
A.	A dropping resistor must be used on the CMOS 12 V supply to reduce it to 5 V for the TTL.
B.	As long as the CMOS supply voltage is 5 V, they can be interfaced; however, the fan-out of the CMOS is limited to two TTL gates.
C.	A 5 V Zener diode must be placed across the inputs of the TTL gates in order to protect them from the higher output voltages of the CMOS gates.
D.	The two series cannot be interfaced without the use of special interface buffers designed for that purpose, such as the open-collector buffers.
Answer» C. A 5 V Zener diode must be placed across the inputs of the TTL gates in order to protect them from the higher output voltages of the CMOS gates.

279.	The simplest equation which implements the K-map shown below is:
A.	<img src="/_files/images/digital-electronics/digital-systems/mca4_1016a1.jpeg">
B.	<img src="/_files/images/digital-electronics/digital-systems/mca4_1016b1.jpeg">
C.	<img src="/_files/images/digital-electronics/digital-systems/mca4_1016c1.jpeg">
D.	<img src="/_files/images/digital-electronics/digital-systems/mca4_1016d1.jpeg">
Answer» B. <img src="/_files/images/digital-electronics/digital-systems/mca4_1016b1.jpeg">

280.	What type of circuit is represented in the given figure, and which statement best describes its operation?
A.	It is a tristate inverter. When the ENABLE input is HIGH, the output is effectively an open circuit it is neither LOW nor HIGH.
B.	It is a programmable inverter. It can be programmed to function as either an active LOW or an active HIGH inverter.
C.	It is an active LOW buffer, which can be turned on and off by the ENABLE input.
D.	None of the above.
Answer» B. It is a programmable inverter. It can be programmed to function as either an active LOW or an active HIGH inverter.

281.	Which of the following logic families has the highest noise margin?
A.	TTL
B.	LS TTL
C.	CMOS
D.	HCMOS
Answer» E.

282.	How many 1-of-16 decoders are required for decoding a 7-bit binary number?
A.	5
B.	6
C.	7
D.	8
Answer» E.

283.	Which of the following logic expressions represents the logic diagram shown?
A.	<img src="/_files/images/digital-electronics/digital-systems/mca4_1018a1.jpeg" align="center">
B.	<img src="/_files/images/digital-electronics/digital-systems/mca4_1018b1.jpeg" align="center">
C.	<img src="/_files/images/digital-electronics/digital-systems/mca4_1018c1.jpeg" align="center">
D.	<img src="/_files/images/digital-electronics/digital-systems/mca4_1018d1.jpeg" align="center">
Answer» E.

284.	Which of the following summarizes the important features of ECL?
A.	Low noise margin, low output voltage swing, negative voltage operation, fast, and high power consumption
B.	Good noise immunity, negative logic, high frequency capability, low power dissipation, and short propagation time
C.	Slow propagation time, high frequency response, low power consumption, and high output voltage swings
D.	Poor noise immunity, positive supply voltage operation, good low frequency operation, and low power
Answer» B. Good noise immunity, negative logic, high frequency capability, low power dissipation, and short propagation time

285.	A 74HC147 priority encoder has ten active-LOW inputs and four active-LOW outputs. What would be the state of the four outputs if inputs 4 and 5 are LOW and all other inputs are HIGH?
A.	<img src="/_files/images/digital-electronics/digital-fundamentals/mca6_0110a.gif">
B.	<img src="/_files/images/digital-electronics/digital-fundamentals/mca6_0110b.gif">
C.	<img src="/_files/images/digital-electronics/digital-fundamentals/mca6_0110c.gif">
D.	<img src="/_files/images/digital-electronics/digital-fundamentals/mca6_0110d.gif">
Answer» B. <img src="/_files/images/digital-electronics/digital-fundamentals/mca6_0110b.gif">