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600+ Digital Electronics and Logic Design Solved MCQs

These multiple-choice questions (MCQs) are designed to enhance your knowledge and understanding in the following areas: Computer Science Engineering (CSE) , Electronics and Telecommunication Engineering [ENTC] .

551.

THE GLITCHES DUE TO RACE CONDITION CAN BE AVOIDED BY USING A                     

A. gated flip- flops
B. pulse triggered flip-flops
C. positive- edge triggered flip-flops
D. negative -edge triggere d flip- flops
Answer» D. negative -edge triggere d flip- flops
552.

A positive edge-triggered flip-flop changes its state when                             

A. low-to-high transition of clock
B. high-to-low transition of clock
C. enable input (en) is set
D. preset input (pre) is set
Answer» A. low-to-high transition of clock
553.

Flip flops are also called                        

A. bi-stable dualvibrators
B. bi-stable transformer
C. bi-stable multivibrator s
D. bi-stable singlevibra tors
Answer» C. bi-stable multivibrator s
554.

A FIELD-PROGRAMMABLE LOGIC ARRAY CAN BE PROGRAMMED BY THE USER AND NOT BY THE MANUFACTURER.

A. true
B. false
Answer» A. true
555.

THE FOUR OUTPUTS OF TWO 4-INPUT MULTIPLEXERS, CONNECTED TO FORM A 16-INPUT
MULTIPLEXER, ARE CONNECTED TOGETHER THROUGH A 4-INPUT
                  GATE

A. and
B. or
C. nand
D. xor
Answer» B. or
556.

A particular half adder has

A. 2 inputs and 1 output
B. 2 inputs and 2 output
C. 3 inputs and 1 output
D. 3 inputs and 2 output
Answer» B. 2 inputs and 2 output
557.

A full-adder has a Cin = 0. What are the sum (<PRIVATE "TYPE=PICT;ALT=sigma"> ) and the carry (Cout) when A = 1 and B = 1?

A. = 0, cout = 0
B. = 0, cout = 1
C. = 1, cout = 0
D. = 1, cout = 1
Answer» B. = 0, cout = 1
558.

The sequence of states that are implemented by a n-bit Johnson counter is

A. n+2 (n plus 2)
B. 2n (n multiplied by 2)
C. 2n (2 raise to power n)
D. n2 (n raise to power 2)
Answer» B. 2n (n multiplied by 2)
559.

A GAL is essentially a .

A. non- reprogrammab le pal
B. pal that is programmed only by the manufacture r
C. very large pal
D. reprogra mmable pal
Answer» D. reprogra mmable pal
560.

The alternate solution for a demultiplexer-register combination circuit is                 

A. parallel in / serial out shift register
B. serial in / parallel out shift register
C. parallel in / parallel out shift register
D. serial in / serial out shift register
Answer» B. serial in / parallel out shift register
561.

A transparent mode means                      

A. the changes in the data at the inputs of the latch are seen at the output
B. the changes in the data at the inputs of the latch are not seen at the output
C. propagation delay is zero (output is immediately changed when clock signal is applied)
D. input hold time is zero (no need to maintain input after clock transition)
Answer» A. the changes in the data at the inputs of the latch are seen at the output
562.

                 occurs when the same clock signal arrives at different times at different clock inputs due to propagation delay.

A. race condition
B. clock skew
C. ripple effect
D. none of given options
Answer» B. clock skew
563.

                    is one of the examples of asynchronous inputs.

A. j-k input
B. s-r input
C. d input
D. clear input (clr)
Answer» D. clear input (clr)
564.

Bi-stable devices remain in either of their states unless the inputs force the device to switch its state

A. ten
B. eight
C. three
D. two
Answer» D. two
565.

RCO Stands for                 

A. reconfiguratio n counter output
B. reconfigurati on clock output
C. ripple counter output
D. ripple clock output
Answer» D. ripple clock output
566.

A positive edge-triggered flip-flop changes its state when                             

A. low-to-high transition of clock
B. high-to-low transition of clock
C. enable input (en) is set
D. preset input (pre) is set
Answer» A. low-to-high transition of clock
567.

The low to high or high to low transition of the clock is considered to be a(n)                

A. state
B. edge
C. trigger
D. one-shot
Answer» B. edge
568.

In asynchronous digital systems all the circuits change their state with respect to a common clock

A. true
B. false
Answer» B. false
569.

If the S and R inputs of the gated S-R latch are connected together using a gate then there is only a single input to the latch. The input is represented by D instead of S or R (A gated D-Latch)

A. and
B. or
C. not
D. xor
Answer» C. not
570.

If S=1 and R=0, then Q(t+1) = for positive edge triggered flip-flop

A. 0
B. 1
C. invalid
D. input is invalid
Answer» B. 1
571.

3-to-8 decoder can be used to implement Standard SOP and POS Boolean expressions

A. true
B. false
Answer» A. true
572.

The Encoder is used as a keypad encoder.

A. 2-to-8 encoder
B. 4-to-16 encoder
C. bcd-to- decimal
D. decimal- to-bcd priority
Answer» D. decimal- to-bcd priority
573.

The simplest and most commonly used Decoders are the Decoders

A. n to 2n
B. (n-1) to 2n
C. (n-1) to (2n- 1)
D. n to 2n-1
Answer» A. n to 2n
574.

A Karnaugh map is similar to a truth table because it presents all the possible values of input variables and the resulting output of each value.

A. true
B. false
Answer» A. true
575.

The decimal “17” in BCD will be represented as 10001(right opt is not given)

A. 11101
B. 11011
C. 10111
D. 11110
Answer» C. 10111
576.

Q2 :=Q1 OR X OR Q3 The above ABEL expression will be

A. q2:= q1 $ x $ q3
B. q2:= q1 # x # q3
C. q2:= q1 & x & q3
D. q2:= q1 ! x ! q3
Answer» B. q2:= q1 # x # q3
577.

Above is the circuit diagram of              

A. asynchronous up-counter
B. asynchronou s down- counter
C. synchronous up-counter
D. synchrono us down- counter
Answer» A. asynchronous up-counter
578.

The high density FLASH memory cell is implemented using                          

A. 1 floating-gate mos transistor
B. 2 floating- gate mos transistors
C. 4 floating- gate mos transistors
D. 6 floating- gate mos transistors
Answer» A. 1 floating-gate mos transistor
579.

A bidirectional 4-bit shift register is storing the nibble 1110. Its input is LOW. The nibble 0111 is waiting to be entered on the serial data-input line. After two clock pulses, the shift register is storing .

A. 1110
B. 111
C. 1000
D. 1001
Answer» D. 1001
580.

At T0 the value stored in a 4-bit left shift was “1”. What will be the value of register after three clock pulses?

A. 2
B. 4
C. 6
D. 8
Answer» D. 8
581.

A multiplexer with a register circuit converts         

A. serial data to parallel
B. parallel data to serial
C. serial data to serial
D. parallel data to parallel
Answer» B. parallel data to serial
582.

In outputs depend only on the combination of current state and inputs

A. mealy machine
B. moore machine
C. state reduction table
D. state assignmen t table
Answer» A. mealy machine
583.

The input overrides the input

A. asynchronous, synchronous
B. synchronous, asynchronou s
C. preset input (pre), clear input (clr)
D. clear input (clr), preset input (pre)
Answer» A. asynchronous, synchronous
584.

For a gated D-Latch if EN=1 and D=1 then Q(t+1) =                 

A. 0
B. 1
C. q(t)
D. invalid
Answer» B. 1
585.

If S=1 and R=1, then Q(t+1) = for negative edge triggered flip- flop

A. 0
B. 1
C. invalid
D. input is invalid
Answer» C. invalid
586.

The sequence of states that are implemented by a n-bit Johnson counter is

A. n+2
B. 2n
C. 2 raise to power n
D. n raise to power 2
Answer» B. 2n
587.

The alternate solution for a multiplexer and a register circuit is

A. parallel in / serial out shift register
B. serial in / parallel out shift register
C. parallel in / parallel out shift register
D. serial in / serial out shift register
Answer» A. parallel in / serial out shift register
588.

THE GLITCHES DUE TO RACE CONDITION CAN BE AVOIDED BY USING A

A. gated flip- flops
B. pulse triggered flip-flops
C. positive- edge triggered flip-flops
D. negative -edge triggere d flip- flops
Answer» D. negative -edge triggere d flip- flops
589.

Flip flops are also called                        

A. bi-stable dualvibrators
B. bi-stable transformer
C. bi-stable multivibrator s
D. bi-stable singlevibra tors
Answer» C. bi-stable multivibrator s
590.

A transparent mode means                        

A. the changes in the data at the inputs of the latch are seen at the output
B. the changes in the data at the inputs of the latch are not seen at the output
C. propagation delay is zero (output is immediately changed when clock signal is applied)
D. input hold time is zero (no need to maintain input after clock transition)
Answer» A. the changes in the data at the inputs of the latch are seen at the output
591.

Given the state diagram of an up/down counter, we can find                

A. the next state of a given present state
B. the previous state of a given present state
C. both the next and previous states of a given state
D. the state diagram shows only the inputs/out puts of a given states
Answer» A. the next state of a given present state
592.

In Q output of the last flip-flop of the shift register is connected to the data input of the first flip-flop of the shift register.

A. moore machine
B. meally machine
C. johnson counter
D. ring counter
Answer» D. ring counter
593.

status.

A. 3
B. 7
C. 8
D. 15
Answer» C. 8
594.

We have a digital circuit. Different parts of circuit operate at different clock frequencies (4MHZ, 2MHZ and 1MHZ), but we have a single clock source having a fix clock frequency (4MHZ), we can get help by

A. using s-r flop- flop
B. d-flipflop
C. j-k flip-flop
D. t-flip-flop
Answer» C. j-k flip-flop
595.

If S=1 and R=1, then Q(t+1) = for negative edge triggered flip- flop

A. 0
B. 1
C. invalid
D. input is invalid
Answer» C. invalid
596.

WHEN BOTH THE INPUTS OF EDGE-TRIGGERED J-K FLOP-FLOP ARE SET TO LOGIC ZERO

A. the flop- flop is triggered
B. q=0 and q‟=1
C. q=1 and q’=0
D. the output of flip- flop remains unchang ed
Answer» C. q=1 and q’=0
597.

If an S-R latch has a 1 on the S input and a 0 on the R input and then the S input goes to 0, the latch will be

A. set
B. reset
C. invalid
D. clear
Answer» A. set
598.

For a positive edge-triggered J-K flip-flop with both J and K HIGH, the outputs will if the clock goes HIGH.

A. toggle
B. set
C. reset
D. not change
Answer» A. toggle
599.

What is the difference between a D latch and a D flip-flop?

A. the d latch has a clock input.
B. the d flip- flop has an enable input.
C. the d latch is used for faster operation.
D. the d flip- flop has a clock input.
Answer» D. the d flip- flop has a clock input.
600.

A frequency counter                          

A. counts pulse width
B. counts no. of clock pulses in 1 second
C. counts high and low range of given clock pulse
D. none of given options
Answer» B. counts no. of clock pulses in 1 second

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