True/False
Indicate whether the
statement is true or false.
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1.
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With a counter circuit, when a counter modulus is not equal to a power of two
there are unused states in the counter’s sequence.
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2.
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In a Moore machine, the next state depends on the present state and the state of
one or more control inputs.
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3.
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The number of flip-flops in a state machine’s memory section is the same
as the number of state variables.
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4.
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An unconditional transition happens under all conditions of input and is labeled
with an X for each input variable.
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5.
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The next state and output of the circuit of a Mealy machine depend only on its
present state.
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Multiple Choice
Identify the
choice that best completes the statement or answers the question.
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6.
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A state machine input that directs the machine from state to state is
the:
a. | control input | c. | control circuit | b. | parallel transfer | d. | frequency
division |
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7.
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A ______ is a circle in a state diagram containing the state name and values of
the state variables.
a. | rotation | c. | ring counter | b. | predictable sequence | d. | bubble |
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8.
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A ______ consists of a memory section that holds the present state of the
machine and a control section that determines the machine’s next state.
a. | shift register | c. | counter modulus | b. | state machine | d. | synchronous
counter |
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9.
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A state machine that has two states requires:
a. | only one state variable | c. | four state
variables | b. | two state variables | d. | no state variables |
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10.
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Counters are special examples of state machines: a MOD-10 down counter that is
currently on state 7 will go to state ______ on a clock edge.
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11.
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______ outputs are susceptible to asynchronous output changes if a combinational
input changes out of synchronization with the clock.
a. | Control scheme | c. | Control | b. | Cycle | d. | Mealy machine |
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12.
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Two types of ______ are Moore machines and Mealy machines.
a. | digital system applications | c. | digital
counters | b. | designs | d. | state machines |
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13.
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A mod-10 counter has six unused states, as the counter requires four bits to
express ten states and the maximum number of 4-bit states is ______.
a. | ten | c. | twelve | b. | sixteen | d. | four |
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14.
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______ can be dealt with in two ways: they can be treated as don’t care
states, or they can be assigned specific destinations in the state diagram.
a. | Power-of-two states | c. | Unused states | b. | State variables | d. | State machines |
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15.
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A machine with five states requires three state variables; there are up to eight
states available in a machine with three state variables, leaving _____ unused states.
a. | ten | c. | three | b. | eight | d. | five |
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16.
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The number of state variables in a machine is equivalent to the number of
______.
a. | unused states | c. | inputs | b. | outputs | d. | flip-flops |
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17.
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A state machine whose output is determined by both the sequential logic and the
combinational logic of the machine is a:
a. | Mealy machine | c. | single-pulse generator | b. | Moore
machine | d. | counter
circuit |
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18.
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Output changes of a Moore machine will always be ______ with the system
clock.
a. | synchronous | c. | conditional | b. | asynchronous | d. | unconditional |
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19.
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A state machine whose output is determined only by the sequential logic of the
machine is a:
a. | sequential logic circuit | c. | predictable sequence
circuit | b. | Moore machine | d. | Mealy machine |
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20.
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A state machine is a digital circuit that goes through a predictable sequence of
states depending on the:
a. | state name and state variables | c. | current state and current
inputs | b. | present state/output combination | d. | control output |
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