ECE 314- Logic Circuits and Switching Theory Finals MCQ
5
A register stores a numerical value representing a binary number. After a positive integer x is entered in the register, the following operation is performed: "shift the register value two bits to the left and add x." How many times as large as x is the new value of the register? Here, the shift does not cause an overflow.
each FF
A ripple counter's speed is limited by the propagation delay of
shift register sequencer
A sequence of equally spaced timing pulses may be easily generated by which type of counter circuit?
decade counter
Another name for a BCS counter:
Multiplexer
Another name for data selector is
high-frequency applications are limited because of internal propagation delays
One of the major drawbacks to the use of asynchronous counter is that:
x+x/2= 2^(2n)-1
When a certain natural number x can be represented by a 2n-digit binary number consisting if 1 and 0 arranged alternately, i.e. 1010...10, which of the following equations holds for x?
If there no cycles among its unused states
When a circuit is self-correcting?
1,1
When flip-flop is set, what are the states of Q and complement Q?
Loss of trailing digits
When multiple values are added arithmetically, it is recommended that the values be added sequentially, starting from the number whose absolute value is the smallest. Which of the following errors can be reduced by means of this method?
1111.111
When the binary fraction 11101.110 is subtracted from the binary fraction 101101.101, what is the correct result?
7
When three flip-flops are used to make a counter, the highest decimal number that can be obtained for display is
input variables
Which among the following state machine notations are generated outside the sequential circuits?
state assignment
Which mechanism allocates the binary value to the states in order to reduce the cost of the combinational circuits?
time-delay devices & flip-flops
Which memory elements are utilized in an asynchronous and clocked sequential circuits respectively?
z = x1 ⋅ x2 + x2 ⋅ x3+ x1 ⋅ x3
Which of the following Boolean expressions is equivalent to the sentence below? "The output z is true if at least two of the three inputs x1, x2, and x3 are true." Here, xn̄is used for the logical negation of xn, "+" for the logical sum, "." For the logical product, and "⊕" for the exclusive disjunction (or exclusive OR)
The bit-by-bit logical product between x and the binary number 00001111 is 0.
Which of the following is appropriate way to check whether or not an 8-bit unsigned binary number x is a multiple of 16?
2^5 + 2^3 + 2^1 + 2^-2 + 2^-5 + 2^-6
Which of the following is equal to the hexadecimal fraction 2A.4C?
NOR gate
Which of the following is not a sequential logic circuit?
magnetic disc
Which of the following memories has the highest storage capacity?
A logical product (i.e. AND) with a bit string 0F in hexadecimal
Which of the following operations does not change the lower 4 bits of an amazing 8-bit string?
0V
Which of the following voltages might normally represent 1 in negative logic?
4V
Which of the following voltages might normally represent 1 in positive logic?
73/512
Which of these represent the hexadecimal fraction 0.248 in decimal fractions?
Due to its capability to transfer the data into flip-flop
Why the D FF do receives its designation or nomenclature as 'DATA flip-flops'?
512
A memory circuit that has 9 addresses inputs has how many storage locations?
shift register
A register can also be used to provide data movements
present state
According to Moore circuit, the output of synchronous sequential circuit depends on the state of the flip-flop
Inserting an inverter between S and R
Construction of a D flip-flop using RS flip-flop
Delay switch
D flip-flop is use as:
Multiplexer
Data selector is also called?
253.7
Erasing EPROM programming is accomplished by using ultraviolet lights that belongs to the UVC range and has a frequency of:
10111011
Given the binary digits A and B, where A = 01010101 B = 01100110 which of these values corresponds to the result of the operation A + B?
4
How many bytes are needed in order to represent a signed six-digit decimal number as a packed decimal?
low
If X is low, what is the state of X and Y?
Finite State Machine
In this logic, output depends not only on the current inputs but also on the past inputs. It needs some type of memory to remember the past input values.
Johnson Counter
In this type of counter, the complement of the output of the last stage of the shift register is fed back to the D input of the first state.
shift register
It does not have any external gates
Sequential
It refers to the class of logic circuit containing flip-flops
cross coupling
Latches constructed with NOR and NAND gates tend to remain in the latched condition due to which configuration feature?
input that they process
Major difference between various types of FFs are
fabrication
Memory can be classified on the basis of what technology used?
area efficiency
Number of stored bits per unit area, which determines overall storage capacity and memory cost per bit.
0.05
Of the following decimal fractions, which becomes an infinite binary fraction when expressed as a binary number
asynchronous circuits
Race condition occurs in
both outputs are low or high
The ambiguous state in a latch is indicated by which of the following conditions?
3
There are ____ flip-flops for a 3-bit binary counter.
presetting one FF and clearing all the others
To operate correctly, starting a ring counter requires:
1101
Which of the following and invalid code in a BCD counter?
11012 + 416 =1710
Which of the following arithmetic expressions is correct? Here, a number is written in radix notation; that is, a decimal subscript following the number (i.e. number radix) is used to indicate the radix.
Flip-flop
Which of the following circuits is used in memory cells in SRAM, has two stable states, and is a basic component of a sequential circuit?
0.5
Which of the following decimal fractions becomes a finite fraction when converted to an octal number?
BE
Which of these values is the correct result of the subtraction of the hexadecimal number DD and IF "DD-IF"
3.5
Which of these values represents in decimal numbers the result of the addition of the binary numbers 1.1011 and 1.1101?
asynchronous
Which sequential circuits generate the feedback path due to the cross-coupled connection from output of one gate to the input of another gate?
state table
Which table indicates the input conditions of the flip-flops necessary to cause all possible next state transitions of a flip-flop?
S0 → S1 → S2 → S1 → S2 → S0
From the state diagram shown below, which of the following transitions is not possible in the diagram? Here, 𝑆0, 𝑆1 𝑎𝑛𝑑 𝑆2. Each edge is labeled with "j/k" where j is the input and k is the output.
X* and y
Given the bit strings x = 1100 and y = 1010, what operation yields the string 1011? Here , "AND", "OR" and "Z*" refer to logical product, logical sum, and negation of Z, respectively.
x* and y
Given the bit strings x = 1100 and y = 1010, what operation yields the string 1011? Here , "AND", "OR" and "Z*" refer to logical product, logical sum, and negation of Z, respectively.
Combinational
How is a full adder classified?
12 AND gates and two 4-bit binary adders
How many AND gates and 4-bit binary adders are needed to implement a 4- bit to 3-bit binary multiplier?
6
How many BCD counters does it take to count to 102557?
4
How many basic types of shift registers
17
How many digits would be required in order to express the greatest possible 14-digit hexadecimal number in decimal notation? Assume 𝑙𝑜𝑔10 2 = 0.301.
2^24 x 16
How many memory cells (or latches for holding 1 bitt each) are implemented in SRAM with 24 address lines and 16 data lines?
2 to 4 line decoder with 1 OR gate*
If F= ab+a'b' expression is to be implemented using decoders and OR gates, the connection should use:
1 MHz, 50 percent
In a JK FF, J = K + 1, PR = 0, C = 1. The CLK input is at 2 MHz with a duty cycle of 30 percent. What is the frequency and duty cycle of the Q output?
The selected output will be low
In a multiple output decoder made with NAND gates, which of the following is true?
70
In an 8-bit code, how many cases are there where the number of 0 bits equals the number of 1 bits
70
In an 8-bit code, how many cases are there where the number of 0 bits equals the number of 1 bits?
4
In designing a 16 x 1 multiplexer, how many selection lines are needed?
2
In designing a 4 x 2 ROM, how many input lines are needed?
Ring counter
In this type of counter, the output of the last stage is connected to the D input of the first stage.
register
It is a circuit that cycles through a sequence of states.
OR
It is a gate which has 2 or more low input signals to get low output
RS
It is an asynchronous latch/FF which can be constructed from the two NAND gates connected back to back.
Hold time
It is required interval immediately following the active edge held of clocks during which the control inputs must be held
Set-up time
It is required interval immediately following the active edge of the clock signal during which the control inputs must be held stable.
Code converter
The circuit that would change the pure binary code into ASCII is called:
ring register
The counter which requires maximum number of flip-flop for a given MOD number is
Edge-triggered
The flip-flop can change only when the appropriate clock transitions occurs. It is called
25 Mhz
The maximum frequency to which 4 bit binary counter using 4 JK FF with a propagation delay time of 10 nanosecond is:
MOD number
The number of states through which the counter goes is also known as what?
ROM
The organization of this device is essentially an array of selectively open and closed unidirectional contacts.
one half of the input frequency
The output frequency of a T flip-flop is?
Excitation table of MOD N counter using JK
The table which shows the necessary levels at J and K input to produce every possible FF state transition is called?
156
There is an 8-bit numerical value, where a negative number is represented in two's complement. When this value is represented in decimal, it becomes -100. When this value is regarded as an unsigned number, which of the following is the correct value in decimal?
256
Two cascaded BCD counters divide an input frequency by:
J=1, K=0
What JK input condition will always set Q upon the occurrences of the active clock transition?
XOR
What do you call a logic gate that has an output of 1 only if a single input is 1?
the output word decrease by 1
What happens to the parallel output word in an asynchronous binary down counter whenever a clock pulse occur?
bidirectional universal
What is a shift register that will accept a parallel input and can shift data left or right called?
Half adder
What is an arithmetic circuit that generates the binary sum of two binary digits?
0100 0011 0010 1100
What is the bit pattern for the decimal number +432 when expressed in packed decimal representation? Assume that the last four bits represent the sign, where "1100" represents + and "1101" represents -
Binary counter
What is the counter that follows the binary sequence?
0156
What is the equivalent of decimal 110 when transformed to 4 digit octal number?
5 kHz
What is the output frequency of a decade counter which is clocked from 50 kHz signals is?
0.FB70
What is the product of the hexadecimal number 0.FEDC multiplied by four?
One
What signal represents the true signal in a truth table?
08
What will be the result if you subtract a hexadecimal number 2C from the decimal number 100, and then subtract again octal number 70?
