Deck 6: Functions of Combinational Logic

Question 1

In binary addition, 1 + 0 = 1.

Answer 1

True

Question 2

In binary addition, 0 + 0 = 00.

Answer 2

True

Question 3

In binary addition, 1 + 1 = 10.

Answer 3

True

Question 4

A half- adder has no carry- in bit.

Question 5

A group of four bits is called a byte.

Question 6

Adders with greater bit capacities can be constructed by connecting 2- bit adders in parallel.

Question 7

Full- adders do not provide for a carry input or a carry output.

Question 8

The look- ahead- carry adder is slower than the ripple- carry adder because it requires additional logic circuits.

Question 9

When paralleling 2- bit full- adders, the carry- out of each stage is connected to the carry- in of the next- higher stage.

Question 10

Full- adders can be used as a BCD- to- binary converters.

Question 11

A BCD- to- decimal decoder can be classified as a 4- line to 10- line decoder.

Question 12

A BCD- to- 7- segment decoder can be classified as a 10- line to 7- line decoder.

Question 13

The function of a decoder is to break a decimal or other character code down into a binary code.

Question 14

Converting a decimal number to its binary equivalent is an example of encoding.

Question 15

A multiplexer has multiple inputs and a single output.

Question 16

Demultiplexers are also known as data distributors.

Question 17

A demultiplexer has multiple inputs and a single output.

Question 18

A demux basically reverses the function of a mux.

Question 19

A mux basically reverses the function of a demux.

Question 20

Decoder glitches can be eliminated by a method known as stripping.

Question 21

The carry output of a half- adder can be expressed as _________.

A) C_out = A + B
B) C_out = AB
C) ?
D) none of these

Question 22

The expression A BB represents_________.

A) the sum output of a full- adder
B) the carry output of a full- adder
C) the carry output of a half- adder
D) the sum output of a half- adder

Question 23

?

-The symbol in Figure 6- 1 represents a(n)_______.

A) PLD
B) half- adder
C) full- adder
D) AND function

Question 24

?

-Refer to the symbol in Figure 6- 1. When A = 0 and B = 1, _______..

A) ?= 1, C_out = 1
B) ? = 1, C_out = 0
C) ? = 0, C_out = 1
D) ? = 0, C_out = 0

Question 25

?

-Referring to the symbol in Figure 6- 1, which combination of outputs should never occur?

A) ? = 0, C_out = 0
B) ? = 1, C_out = 0
C) ? = 0, C_out = 1
D) ?= 1, C_out = 1

Question 26

What is the major difference between half- adders and full- adders?

A) Full- adders are made up of two half- adders.
B) Half- adders can only handle single digit numbers.
C) Full- adders can handle double digit numbers.
D) Full- adders have a carry input capability.

Question 27

Which of the following is correct for full- adders?

A) Full- adders are limited to two inputs, since there are only two binary digits.
B) Full- adders have the capability of directly adding decimal numbers.
C) Full- adders are used to make half- adders.
D) The first stage of a parallel full- adder may be a half- adder.

Question 28

The expression ? describes _______. .

A) the sum output of a half- adder
B) the carry output of a full- adder
C) the carry output of a half- adder
D) the sum output of a full- adder

Question 29

The expression ? describes _______.

A) the sum output of a full- adder
B) the carry output of a half- adder
C) the carry output of a full- adder
D) the sum output of a half- adder

Question 30

-The symbol in Figure 6- 2 represents a(n)_________.

A) half- adder
B) And function
C) full- adder
D) PLD

Question 31

-Refer to the symbol in Figure 6- 2. What are the output when A = 1, B = 1, C_in = 0?

A) ? = 1, C_out = 0
B) ? =1, C_out = 1
C) ? = 0, C_out = 0
D) ? = 0, C_out = 1

Question 32

-Refer to the symbol in Figure 6- 2. What are the output when A = 1, B = 1, C_in = 1?

A) ?=1, C_out = 1
B) ? = 1, C_out = 0
C) ? = 0, C_out = 1
D) ? = 0, C_out = 0

Question 33

What is one disadvantage of the ripple- carry adder?

A) More stages are required to a full- adder.
B) It is slow, due to propagation time.
C) The interconnections are more complex.
D) All of the above are correct.

Question 34

What is one advantage of the look- ahead- carry adder?

A) It is slower than the ripple- carry adder.
B) It is faster than a ripple- carry adder.
C) It is easier to implement logically than a full- adder.
D) It requires advance knowledge of the final answer.

Question 35

Which of the following is true for IC comparator circuits?

A) All comparators have outputs for indicating AB, and A=B.
B) Comparators can compare only two values at a time.
C) Comparators can compare only 2 bits at a time.
D) None of these

Question 36

The circuit below can be used as a(n) _________.

A) dual 4- line multiplexer
B) 4- bit comparator
C) 8- bit comparator
D) 4- bit half- adder

Question 37

Which statement below best describes the function of a decoder?

A) A decoder will convert a decimal number into the proper binary equivalent.
B) Decoders are used to prevent improper operation of digital systems.
C) A decoder will convert a binary number into a specific output representing a particular character or digit.
D) Decoders are special ICs that are used to make it possible for one brand of computer to talk to another.

Question 38

The function can be decoded with _________.

A) two 2- input OR gates and two inverters
B) one 4- input AND gate and one inverter
C) one 4- input AND gate and two inverters
D) two 2- input OR gates and one inverter

Question 39

-The output of the decoder in Figure 6- 3 will be 1 only when ________.

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

Question 40

-The boolean expression for the decoder in Figure 6- 3 is ________.

A)
B) X = ABCD
C)
D) None of these

Question 41

A 1- of- 16 decoder IC has ________data input connection(s).

A) 4
B) 8
C) 1
D) 16

Question 42

A BCD- to- decimal decoder has________ data input lines and ________ data output lines.

A) 10,10
B) 1,10
C) 4, 10
D) 7,9

Question 43

The symbol below most likely represents a ________.

A) demultiplexer
B) multiplexer
C) comparator
D) full- adder

Question 44

What is another name used for a multiplexer?

A) Attenuator
B) Demultiplexer
C) Data selector
D) Multiplier

Question 45

A multiplexer with four select, or address, lines can select one of _______inputs.

A) 16
B) 15
C) 7
D) 3

Question 46

The symbol below most likely represents a _________.

A) multiplexer
B) demultiplexer
C) comparator
D) full- adder