A+ Answers



What is another name used for a multiplexer?
Question 1 options:
attenuator
multiplier
data selector
ademultiplexer
Question 2
 A multiplexer with three select, or address, lines can select one of ________ inputs.
Question 2 options:
3
8
16
7
Question 3
A multiplexer/data selector is a logic circuit that:
Question 3 options:
Accepts data inputs from one line and passes this data to multiple output lines.
Accepts data inputs from several lines and multiplexes this input data to four BCD lines.
Accepts data inputs from several lines and allows one of them at a time to pass to the output.
Accepts data inputs from multiple lines and passes this data to multiple output lines.
Question 4
A BCD to decimal decoder would be required to have:
Question 4 options:
Ten input lines and four output lines.
Three input lines and nine output lines.
Nine input lines and three output lines.
Four input lines and ten output lines
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Question 5
A demultiplexer accepts data from:
Question 5 options:
Sequential input lines and transfers it to one output line.
Multiple input lines and transfers it to one output line.
One input line and transfers it to multiple output lines.
One input line and transfers it to one output line after conditioning and buffering the data signals.
Question 6
Decoders are normally used whenever:
Question 6 options:
Outputs are to be activated on a random time-share basis independent of the input combinations.
Inputs are totally random and the active outputs are nonsequential.
Outputs are to be activated that are identical to the multiple inputs.
An output or group of outputs is to be activated only when a specific combination of inputs occur.
Question 7
A three-line-to-eight line decoder has inputs CBA where A is the LSB. The output AND gates are labeled Q0 through Q7. The output of AND gate Q4 should be active when the inputs are:
Question 7 options:
C A.
C   .
 BA.
CB .
Question 8
The primary differences between a decoder and an encoder are:
Question 8 options:
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.
Decoders will have only one input line active but may have more than one output line active at any given time.
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 tine.
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.
Question
How many input lines would be required for a 1-of-8 decoder?
Question 9 options:
4
3
5
2
Question 10
The output lines for a demultiplexer are under the direct control of the:
Question 10 options:
Internal AND gates.
Input data-select lines.
Internal OR gate.
Input data line.
Question 11
A 1-of16 decoder IC has ________ data input connection(s).
Question 11 options:
16
1
4
8
Question 12
A BCD-to-decimal decoder has ________ data input lines and ________ data output lines.
Question 12 options:
10,10
7,9
4, 10
1,10
Question 13
The parallel data from a branch bank’s computer terminal is to be transferred over telephone lines to the main bank’s computer. You would expect to find a __________ at the transmitting end and __________ a at the receiving end.
Question 13 options:
demultiplexer, multiplexer
multiplexer, demultiplexer
Question 14
One would normally expect a 16-input multiplexer to have a minimum of:
Question 14 options:
16-input data lines and two input select lines.
16-input data lines and three input select lines.
16-input data lines and five input select lines.
16-input data lines and four input select lines
Question 15
A certain BCD-to-decimal decoder has four input lines and 10 output lines. If four input lines are capable of 16 possible combinations and only 10 output combinations are required, why have four inputs?
Question 15 options:
With four input lines, the decoder can provide for those rare occasions when input codes greater than 10012 may require decoding.
With three input lines the maximum number of output combinations would be limited to eight.
With three input lines the maximum number of output combinations would be equal to nine, including zero, and this would be sufficient, but decoders are not manufactured with only three inputs.
Both A and C
Question 16
What is the purpose of a decoder’s enable inputs?
Question 16 options:
To disable the decoder outputs so that all outputs will be inactive
To disable the inputs and activate all outputs
To allow the decoder to respond to the inputs to activate the correct output gate
Both A and C
Question 17
Internal computer registers that store data are often connected to the computer data bus lines by:
Question 17 options:
Totem-pole output devices.
Tri-state buffers.
Open-collector devices.
Quad input AND gates.
Question 18
 Usually, a decoder circuit without bubbles on the outputs has only one output HIGH while all the other outputs are LOW.
Question 18 options:
True
False
Question 19
The given figure depicts a circuit that implements a 3 variable function F(A,B,C) using a 4 to 1 Multiplexer. The truth table specify the behavior of the multiplexer. Which one of the three options given realizes the circuit?
Question 19 options:
a)Option 1
b)Option 2
c)Option 3
d)None of the option shown
Question 20
The given figure depicts a circuit that implements a two outputs,  4 variable functions f1(a,b,c,d) and f2(a,b,c,d) using a 4 to 10 line decoder 7442 and two three input nand gates.  Which functions f1 and f2 realizes the circuit?
Question 20 options:
a)f1(a,b,c,d)= abcd’+ abc’d + ab’cd
f2(a,b,c,d)= ab’cd+ ab’c’d’ + a’bcd
b)f1(a,b,c,d)= a’b’c’d+ a’b’cd’ + a’bc’d’
f2(a,b,c,d)= a’bc’d’+ a’bcd + ab’c’d
c)f1(a,b,c,d)= (a+b+c’+d)(a+b+c’+d)(a+b’+c+d)
f2(a,b,c,d)= (a+b’+c+d)(a+b’+c’+d’)(a’+b+c+d’)
d)None of the above
Question 21 
The figure shows a typical circuit for a BCD to Seven Segment Decoder driving a Seven Segment Display and the diferent configuarations of the led for each character. If the inputs to the decoder are A=B=C=D=0 which outputs are high?
Question 21 options:
All outputs are high
None of the outputs are high
All outputs but g’ are high.
g’ is the only output that is high.