digital Concepts (logic) Flashcards by XYRA Unknown

Any number with an exponent of zero is equal to:
zero
one
that number
ten

one

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In the decimal numbering system, what is the MSD?
The middle digit of a stream of numbers
The digit to the right of the decimal point
The last digit on the right
The digit with the most weight

The digit with the most weight

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Which of the following statements does NOT describe an advantage of digital technology?
The values may vary over a continuous range.
The circuits are less affected by noise.
The operation can be programmed.
Information storage is easy.

The values may vary over a continuous range.

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The generic array logic (GAL) device is ________.
one-time programmable
reprogrammable
a CMOS device
reprogrammable and a CMOS device

reprogrammable

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The range of voltages between VL(max) and VH(min) are ________.
unknown
unnecessary
unacceptable
between 2 V and 5 V

unacceptable

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What is a digital-to-analog converter?
It takes the digital information from an audio CD and converts it to a usable form.
It allows the use of cheaper analog techniques, which are always simpler.
It stores digital data on a hard drive.
It converts direct current to alternating current.

It takes the digital information from an audio CD and converts it to a usable form.

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What are the symbols used to represent digits in the binary number system?
0,1
0,1,2
0 through 8
1,2

0,1

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A full subtracter circuit requires ________.
two inputs and two outputs
two inputs and three outputs
three inputs and one output
three inputs and two outputs

three inputs and two outputs

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Parallel format means that:
each digital signal has its own conductor.
several digital signals are sent on each conductor.
both binary and hexadecimal can be used.
no clock is needed.

each digital signal has its own conductor.

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A decoder converts ________.
noncoded information into coded form
coded information into noncoded form
HIGHs to LOWs
LOWs to HIGHs

coded information into noncoded form

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A DAC changes ________.
an analog signal into digital data
digital data into an analog signal
digital data into an amplified signal
none of the above

digital data into an analog signal

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Which of the following is not an analog device?
Thermocouple
Current flow in a circuit
Light switch
Audio microphone

Light switch

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A demultiplexer has ________.
one data input and a number of selection inputs, and they have several outputs
one input and one output
several inputs and several outputs
several inputs and one output

one data input and a number of selection inputs, and they have several outputs

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A flip-flop has ________.
one stable state
no stable states
two stable states
none of the above

two stable states

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Digital signals transmitted on a single conductor (and a ground) must be transmitted in:
slow speed.
parallel.
analog.
serial.

serial.

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In a certain digital waveform, the period is four times the pulse width. The duty cycle is ________.
0%
25%
50%
100%

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Digital representations of numerical values of quantities may BEST be described as having characteristics:
that are difficult to interpret because they are continuously changing.
that vary constantly over a continuous range of values.
that vary in constant and direct proportion to the values they represent.
that vary in discrete steps in proportion to the values they represent.

that vary in discrete steps in proportion to the values they represent.

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A common instrument used in troubleshooting a digital circuit is a(n) ________.
logic probe
oscilloscope
pulser
all of the above

ll of the above

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The parallel transmission of digital data:
is much slower than the serial transmission of data.
requires only one signal line between sender and receiver.
requires as many signal lines between sender and receiver as there are data bits.
is less expensive than the serial method of data transmission.

requires as many signal lines between sender and receiver as there are data bits.

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What is one relative disadvantage of serial transfer?
It requires too many conductors.
Its interconnect system is complex.
It is slow.
It can only be used over very short distances.

It is slow

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Which format requires fewer conductors?
Parallel
Serial
Both are the same
Cannot tell

Serial

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The rise time is the time it takes a pulse to go from ________.
the base line to the maximum HIGH voltage
10% of the pulse amplitude to the maximum HIGH voltage
the base line to 90% of the pulse amplitude
10% of the pulse amplitude to 90% of the pulse amplitude

10% of the pulse amplitude to 90% of the pulse amplitude

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What is an analog-to-digital converter?
It makes digital signals.
It takes analog signals and puts them in digital format.
It allows the use of digital signals in everyday life.
It stores information on a CD.

It takes analog signals and puts them in digital format.

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A multiplexer has ________.
one input and several outputs
one input and one output
several inputs and several outputs
several inputs and one output

several inputs and one output

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An encoder converts ________. noncoded information into coded form coded information into noncoded form HIGHs to LOWs LOWs to HIGHs

noncoded information into coded form

What kind of logic device or circuit is used to store information? Counter Register Inverter Buffer

PLCC packages have leads on ________. one side two sides three sides four sides

four sides

What is the typical invalid voltage for a binary signal? 0.7–2.8 volts 0.8–3 volts 0.8–2 volts 0.7–2.5 volts

0.8-2 volts

How many binary bits are necessary to represent 748 different numbers? 9 7 10 8

Serial format means digital signals are: sent over many conductors simultaneously. sent over one conductor sequentially. sent in groups of eight signals. sent in binary coded decimal.

sent over one conductor sequentially.

Which format can send several bits of information faster? Parallel Serial Both are the same Cannot tell

Parallel

What has happened to the advances in digital technologies over the past three decades? Slowed down considerably Continued to increase, but at a decreasing rate Made excellent progress Nothing short of phenomenal

Nothing short of phenomenal

A type of digital circuit technology that uses bipolar junction transistors is ________. TTL CMOS LSI NMOS

TTL

How many unique symbols are used in the decimal number system? One Nine Ten Unlimited

Ten

One hex digit is sometimes referred to as a(n): byte nibble grouping instruction

nibble

Which of the following is the most widely used alphanumeric code for computer input and output? Gray ASCII Parity EBCDIC

ASCII

If a typical PC uses a 20-bit address code, how much memory can the CPU address? 20 MB 10 MB 1 MB 580 MB

1 MB

Which is typically the longest: bit, byte, nibble, word? Bit Byte Nibble Word

Word

A binary number's value changes most drastically when the ________ is changed. MSB frequency LSB duty cycle

MSB

Which is not a word size? 64 28 16 8

The octal numbering system: simplifies tasks groups binary numbers in groups of 4 saves time simplifies tasks and saves time

simplifies tasks and saves time

When using even parity, where is the parity bit placed? Before the MSB After the LSB In the parity word After the odd parity bit

Before the MSB

An analog signal has a range from 0 V to 5 V. What is the total number of analog possibilities within this range? 5 50 250 infinite

infinite

Hexadecimal letters A through F are used for decimal equivalent values from: 1 through 6 9 through 14 10 through 15 11 through 17

10 through 15

What is the difference between binary coding and binary-coded decimal? BCD is pure binary. Binary coding has a decimal format. BCD has no decimal format. Binary coding is pure binary.

Binary coding is pure binary.

Digital electronics is based on the ________ numbering system. decimal octal binary hexadecimal

binary

An informational signal that makes use of binary digits is considered to be: solid state digital analog non-oscillating

digital

The binary-coded decimal (BCD) system can be used to represent each of the 10 decimal digits as a(n): 4-bit binary code 8-bit binary code 16-bit binary code ASCII code

4-bit binary code

The American Standard Code for Information Interchange (ASCII) uses how many individual pulses for any given character? 1 2 7 8

Alphanumeric codes should include as a minimum: the capacity to represent the alphabet upper- and lowercase characters and the decimal numbers in a straight binary format. the capacity to code all possible decimal numbers in a direct octal representation of BCD codes. the alphabet upper- and lowercase letters, the decimal digits, the seven punctuation marks, and other characters or symbols. the ability to represent decimal numbers greater than 12810 in a straight binary format.

the alphabet upper- and lowercase letters, the decimal digits, the seven punctuation marks, and other characters or symbols.

Select one of the following statements that best describes the parity method of error detection. Parity checking is best suited for detecting single-bit errors in transmitted codes. Parity checking is not suitable for detecting single-bit errors in transmitted codes. Parity checking is capable of detecting and correcting errors in transmitted codes. Parity checking is best suited for detecting double-bit errors that occur during the transmission of codes from one location to another.

Parity checking is best suited for detecting single-bit errors in transmitted codes.

Which of the following is the primary advantage of using the BCD code instead of straight binary coding? Fewer bits are required to represent a decimal number with the BCD code. The relative ease of converting to and from decimal. BCD codes are easily converted to hexadecimal codes. BCD codes are easily converted to straight binary codes.

The relative ease of converting to and from decimal

When using the repeated division by 2 method of converting from decimal to binary, one must write the first remainder as the: MSB MSB, provided the following sequence of remainders are written in descending order until the final remainder is achieved. LSB LSB, provided the final remainder is used to replace the original LSB, which is then moved to the MSB position.

LSB

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: DMM spectrum analyzer logic analyzer frequency counter

logic analyzer

How many pins does the 4049 IC have? 14 16 18 20

Which of the following choices meets the minimum requirement needed to create specialized waveforms that are used in digital control and sequencing circuits? basic gates, a clock oscillator, and a repetitive waveform generator basic gates, a clock oscillator, and a Johnson shift counter basic gates, a clock oscillator, and a DeMorgan pulse generator basic gates, a clock oscillator, a repetitive waveform generator, and a Johnson shift counter

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

TTL operates from a ________. 9-volt supply 3-volt supply 12-volt supply 5-volt supply

5-volt supply

The switching speed of CMOS is now ________. competitive with TTL three times that of TTL slower than TTL twice that of TTL

competitive with TTL

The format used to present the logic output for the various combinations of logic inputs to a gate is called a(n): Boolean constant Boolean variable truth table input logic function

truth table

The power dissipation, PD, of a logic gate is the product of the ________. dc supply voltage and the peak current dc supply voltage and the average supply current ac supply voltage and the peak current ac supply voltage and the average supply current

dc supply voltage and the average supply current

A CMOS IC operating from a 3-volt supply will consume ________. less power than a TTL IC more power than a TTL IC the same power as a TTL IC no power at all

less power than a TTL IC

What are the pin numbers of the outputs of the gates in a 7432 IC? 3, 6, 10, and 13 1, 4, 10, and 13 3, 6, 8, and 11 1, 4, 8, and 11

3, 6, 8, and 11

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? The dim indication on the logic probe indicates that the supply voltage is probably low. The output of the gate appears to be open. The dim indication is the result of a bad ground connection on the logic probe. The gate is a tristate device.

The output of the gate appears to be open

What is the difference between a 7400 and a 7411 IC? 7400 has two four-input NAND gates; 7411 has three three-input AND gates 7400 has four two-input NAND gates; 7411 has three three-input AND gates 7400 has two four-input AND gates; 7411 has three three-input NAND gates 7400 has four two-input AND gates; 7411 has three three-input NAND gates

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

The AND function can be used to ________ and the OR function can be used to ________ . enable, disable disable, enable enable or disable, enable or disable detect, invert

enable or disable, enable or disable

One advantage TTL has over CMOS is that TTL is ________. less expensive not sensitive to electrostatic discharge faster more widely available

not sensitive to electrostatic discharge

Fan-out is specified in terms of ________. voltage current wattage unit loads

unit loads

What is the circuit number of the IC that contains four two-input AND gates in standard TTL? 7402 7404 7408 7432

7408

The terms "low speed" and "high speed," applied to logic circuits, refer to the ________. rise time fall time propagation delay time clock spee

propagation delay time

The term "hex inverter" refers to: an inverter that has six inputs six inverters in a single package a six-input symbolic logic device an inverter that has a history of failure

six inverters in a single package

How many inputs are on the logic gates of a 74HC21 IC? 1 2 3 4

How many AND gates are found in a 7411 IC? 1 2 3 4

What is the name of a digital circuit that produces several repetitive digital waveforms? an inverter an OR gate a Johnson shift counter an AND gate

a Johnson shift counter

The basic types of programmable arrays are made up of ________. AND gates OR gates NAND and NOR gates AND gates and OR gates

AND gates and OR gates

CMOS IC packages are available in ________. DIP configuration SOIC configuration DIP and SOIC configurations neither DIP nor SOIC configurations

DIP and SOIC configurations

Select the statement that best describes the parity method of error detection: Parity checking is best suited for detecting double-bit errors that occur during the transmission of codes from one location to another. Parity checking is not suitable for detecting single-bit errors in transmitted codes. Parity checking is best suited for detecting single-bit errors in transmitted codes. Parity checking is capable of detecting and correcting errors in transmitted codes.

Parity checking is best suited for detecting single-bit errors in transmitted codes.

Parity systems are defined as either________ or ________ and will add an extra ________ to the digital information being transmitted. positive, negative, byte odd, even, bit upper, lower, digit on, off, decimal

odd, even, bit

The Ex-NOR is sometimes called the ________. parity gate equality gate inverted OR parity gate or the equality gate

equality gate

The systematic reduction of logic circuits is accomplished by: using Boolean algebra symbolic reduction TTL logic using a truth table

using Boolean algebra

What is the primary motivation for using Boolean algebra to simplify logic expressions? It may make it easier to understand the overall function of the circuit. It may reduce the number of gates. It may reduce the number of inputs required. all of the above

all of the above

When grouping cells within a K-map, the cells must be combined in groups of ________. 2s 1, 2, 4, 8, etc. 4s 3s

1, 2, 4, 8, etc.

Occasionally, a particular logic expression will be of no consequence in the operation of a circuit, such as a BCD-to-decimal converter. These result in ________terms in the K-map and can be treated as either ________ or ________, in order to ________ the resulting term. don't care, 1s, 0s, simplify spurious, ANDs, ORs, eliminate duplicate, 1s, 0s, verify spurious, 1s, 0s, simplify

don't care, 1s, 0s, simplify

The NAND or NOR gates are referred to as "universal" gates because either: can be found in almost all digital circuits can be used to build all the other types of gates are used in all countries of the world were the first gates to be integrated

can be used to build all the other types of gates

Which statement below best describes a Karnaugh map? A Karnaugh map can be used to replace Boolean rules. The Karnaugh map eliminates the need for using NAND and NOR gates. Variable complements can be eliminated by using Karnaugh maps. Karnaugh maps provide a cookbook approach to simplifying Boolean expressions.

Karnaugh maps provide a cookbook approach to simplifying Boolean expressions.

Which of the following is an important feature of the sum-of-products (SOP) form of expression? All logic circuits are reduced to nothing more than simple AND and OR gates. The delay times are greatly reduced over other forms. No signal must pass through more than two gates, not including inverters. The maximum number of gates that any signal must pass through is reduced by a factor of two.

No signal must pass through more than two gates, not including inverters.

The commutative law of addition and multiplication indicates that: we can group variables in an AND or in an OR any way we want an expression can be expanded by multiplying term by term just the same as in ordinary algebra the way we OR or AND two variables is unimportant because the result is the same the factoring of Boolean expressions requires the multiplication of product terms that contain like variables

the way we OR or AND two variables is unimportant because the result is the same

Which of the following combinations cannot be combined into K-map groups? corners in the same row corners in the same column diagonal overlapping combinations

diagonal

The format used to present the logic output for the various combinations of logic inputs to a gate is called a(n): truth table. input logic function. Boolean constant. Boolean variable.

truth table.

What is the basic difference between AHDL and VHDL? ADHL is used in all PLD's. VHDL is used in all PLD's. ADHL is proprietary. VHDL is proprietary.

ADHL is proprietary.

In VHDL, the mode of a port does not define: an input. an output. both an input and an output. the TYPE of the bit.

the TYPE of the bit

How are the statements between BEGIN and END not evaluated in VHDL? Constantly Simultaneously Concurrently Sequentially

Sequentially

The special software application that translates from HDL into a grid of 1's and 0's, which can be loaded into a PLD, is called a: formatter. compiler. programmable wiring. CPU.

compiler.

digital Concepts (logic) Flashcards

(92 cards)