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To prevent bus contention problems from occurring from multiple input sources tied to a data bus, every source is connected through _____and held in Hi- Z state by output enable inputs.

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A three line- to- eight line decoder could also be called a(n) :


A) binary to octal decoder.
B) binary to hexadecimal decoder.
C) hexadecimal to binary decoder.
D) octal to binary decoder.

E) B) and C)
F) A) and D)

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A 74HC85 magnitude comparator is used to:


A) compare two input voltage levels and generate outputs to indicate which voltage has the greater magnitude.
B) AND two binary quantities and generate outputs only if they are equal in magnitude.
C) Exclusive OR two binary quantities and generate an output if they are unequal in magnitude.
D) compare two input binary quantities and generate outputs to indicate which quantity has the greater magnitude.

E) None of the above
F) B) and D)

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The decoder described in the preceding question has three inputs labeled A2, A1, and A0 where A2 is the MSB. If the input is 0102, the conditions of the output gates should be:


A) The decoder described in the preceding question has three inputs labeled A<sub>2</sub>, A<sub>1</sub>, and A<sub>0 </sub>where A<sub>2 </sub> is the MSB. If the input is 010<sub>2</sub>, the conditions of the output gates should be: A)   output HIGH and all other gate outputs LOW. B)   output LOW and all other gate outputs HIGH. C)   output HIGH and all other gate outputs LOW. D)   output LOW and all other gate outputs HIGHoutput HIGH and all other gate outputs LOW.
B) 11eea485_0f90_d70c_97f4_83c4ed9fa336_TB9839_11output LOW and all other gate outputs HIGH.
C) 11eea485_1fa8_415d_97f4_05e2805d980c_TB9839_11output HIGH and all other gate outputs LOW.
D) 11eea485_1fa8_415d_97f4_05e2805d980c_TB9839_11output LOW and all other gate outputs HIGH

E) A) and B)
F) A) and C)

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Alphanumeric LCD displays interfaces are standardized so that an LCD module from any manufacturer uses the same signal and data format.

A) True
B) False

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A four- bit magnitude comparator could be _____ with another four- bit comparator to increase resolution.

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How many binary output lines would be required for a four- digit BCD- to- binary converter?


A) 10
B) 16
C) 12
D) 14

E) None of the above
F) All of the above

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A BCD to decimal decoder would be required to have:


A) three input lines and nine output lines.
B) four input lines and ten output lines.
C) nine input lines and three output lines.
D) ten input lines and four output lines.

E) A) and B)
F) B) and C)

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I/O lines that transfer data in either of two directions depending on the state of their enable inputs are called _____data lines.

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A 7445 decoder has IEEE/ANSI symbol internal markings of BCD/DEC with a small triangle underneath. Also, there is an underlined diamond at each output. These symbols mean the device is a:


A) BCD to decimal decoder buffer/driver with open- collector outputs.
B) BCD buffer/driver with totem- pole outputs.
C) decimal buffer/driver with open- collector outputs.
D) BCD to decimal decoder buffer/driver with totem- pole outputs.

E) B) and D)
F) A) and B)

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The primary differences between a decoder and an encoder are:


A) decoders may have more than one input line active at any given time but only one output line will be active. Encoders also may have more than one input line active and may have more than one output line active at any given time.
B) decoders will have only one input line active but may have more than one output line active at any given time.
C) decoders may have only one input line and one output line active at any given time. Encoders may have more than one input and output lines active at any given time.
D) decoders may have more than one input line active but only one output line active at any given time. Encoders will have only one input active but may have more than one output line active at any given time.

E) B) and C)
F) A) and D)

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Select the statement which best describes the application of observation and analysis procedures when troubleshooting complex circuits.


A) A thorough understanding of the proper operation of the test equipment to be used to analyze the fault.
B) A thorough understanding of the operation of the circuit, observing the symptoms caused by the failure and using human reasoning to isolate the fault to a specific area.
C) The capabilities of modern test equipment have virtually eliminated the requirement for observation and analysis procedures when troubleshooting.

D) All of the above
E) A) and B)

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When cascading two 74HC85 magnitude comparators, the outputs of the______order comparator are the final outputs that indicate the results of the comparison.


A) high
B) low

C) A) and B)
D) undefined

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Decoder/drivers, like the TTL7445 can be used to drive loads such as LEDs, lamps, relays, and small DC motors.

A) True
B) False

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Which of the following groups of terms best describes the inputs and the components associated with a multiplexer?


A) Input address lines, inverters, AND gates, and an output OR gate
B) Input data lines, inverters, AND gates, and an output OR gate
C) Input address lines, input data lines, inverters, AND gates, and an output OR gate
D) Input binary data lines, inverters, AND gates, and an output NAND gate

E) B) and D)
F) A) and C)

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A(n)_____ display generates or emits light energy as current is passed through the individual segments.

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CMOS devices are generally used to drive 7- segment LCD displays because:


A) they consume less power than TTL devices and their output in the LOW state is always above
0) 5 v.
B) they are capable of generating an output ac sinewave to drive the 7- segment LCD.
C) they consume less power than TTL devices and their output voltage in the LOW state is usually less than TTL.
D) they consume more power than TTL devices but their output voltage in the LOW state is less than TTL and this extends the useful life of the LCD.

E) B) and C)
F) A) and D)

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Two eight input multiplexers can combine to send data over a single output line. The first step is combining select inputs. To complete the circuit:


A) the enable inputs must be connected together.
B) connect one enable input to the other via and inverter, then connect outputs together through an OR gate.
C) a NOR gate must tie output lines together.
D) tie enables inputs together and install a NAND gate on the outputs.

E) A) and B)
F) A) and C)

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What is the purpose of a decoder's enable inputs?


A) To disable the decoder outputs so that all outputs will be inactive
B) To disable the inputs and activate all outputs
C) To allow the decoder to respond to the inputs to activate the correct output gate
D) Both A and C

E) None of the above
F) C) and D)

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The output lines for a demultiplexer are under the direct control of the:


A) input data- select lines.
B) internal AND gates.
C) internal OR gate.
D) input data line.

E) A) and B)
F) B) and D)

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