340+ Digital Logic Circuits (DLC) Solved MCQs

1.

Any signed negative binary number is recognised by its                  

A. msb
B. lsb
C. byte
D. nibble
Answer» A. msb
2.

The parameter through which 16 distinct values can be represented is known as

A. bit
B. byte
C. word
D. nibble
Answer» C. word
3.

The representation of octal number (532.2)8 in decimal is                  

A. (346.25)10
B. (532.864)10
C. (340.67)10
D. (531.668)10
Answer» A. (346.25)10
4.

The decimal equivalent of the binary number (1011.011)2 is                  

A. (11.375)10
B. (10.123)10
C. (11.175)10
D. (9.23)10
Answer» A. (11.375)10
5.

An important drawback of binary system is                  

A. it requires very large string of 1’s and 0’s to represent a decimal number
B. it requires sparingly small string of 1’s and 0’s to represent a decimal number
C. it requires large string of 1’s and small string of 0’s to represent a decimal number
D. it requires small string of 1’s and large string of 0’s to represent a decimal number
Answer» A. it requires very large string of 1’s and 0’s to represent a decimal number
6.

The decimal equivalent of the octal number (645)8 is              

A. (450)10
B. (451)10
C. (421)10
D. (501)10
Answer» C. (421)10
7.

The largest two digit hexadecimal number is                  

A. (fe)16
B. (fd)16
C. (ff)16
D. (ef)16
Answer» C. (ff)16
8.

Representation of hexadecimal number (6DE)H in decimal:

A. 6 * 162 + 13 * 161 + 14 * 160
B. 6 * 162 + 12 * 161 + 13 * 160
C. 6 * 162 + 11 * 161 + 14 * 160
D. 6 * 162 + 14 * 161 + 15 * 160
Answer» A. 6 * 162 + 13 * 161 + 14 * 160
9.

The quantity of double word is                  

A. 16 bits
B. 32 bits
C. 4 bits
D. 8 bits
Answer» B. 32 bits
10.

What does RTL in digital circuit design stand for?

A. register transfer language
B. register transfer logic
C. register transfer level
D. resistor-transistor logic
Answer» C. register transfer level
11.

RTL is a design abstraction of what kind of circuit?

A. asynchronous digital circuit
B. synchronous digital circuit
C. asynchronous sequential circuit
D. analog circuit
Answer» B. synchronous digital circuit
12.

RTL is used in HDL to create what level of representations in the circuit?

A. high-level
B. low-level
C. mid-level
D. same level
Answer» A. high-level
13.

RTL mainly focuses on describing the flow of signals between                  

A. logic gates
B. registers
C. clock
D. inverter
Answer» B. registers
14.

Which flip-flop is usually used in the implementation of the registers?

A. d flip-flop
B. s-r flip-flop
C. t flip-flop
D. j-k flip-flop
Answer» A. d flip-flop
15.

Which of the following tool performs logic optimization?

A. simulation tool
B. synthesis tool
C. routing tool
D. rtl compiler
Answer» B. synthesis tool
16.

Hold time is the time needed for the data to after the edge of the clock is triggered.

A. decrease
B. increase
C. remain constant
D. negate
Answer» C. remain constant
17.

Simulator enters in which phase after the initialization phase?

A. execution phase
B. compilation phase
C. elaboration phase
D. simulation phase
Answer» A. execution phase
18.

All input of NOR as low produces result as                      

A. low
B. mid
C. high
D. floating
Answer» C. high
19.

In RTL NOR gate, the output is at logic 1 only when all the inputs are at                      

A. logic 0
B. logic 1
C. +10v
D. floating
Answer» A. logic 0
20.

The role of the is to convert the collector current into a voltage in RTL.

A. collector resistor
B. base resistor
C. capacitor
D. inductor
Answer» A. collector resistor
21.

The limitations of the one transistor RTL NOR gate are overcome by                      

A. two-transistor rtl implementation
B. three-transistor rtl implementation
C. multi-transistor rtl implementation
D. four-transistor rtl implementation
Answer» C. multi-transistor rtl implementation
22.

The primary advantage of RTL technology was that                      

A. it results as low power dissipation
B. it uses a minimum number of resistors
C. it uses a minimum number of transistors
D. it operates swiftly
Answer» C. it uses a minimum number of transistors
23.

The disadvantage of RTL is that                      

A. it uses a maximum number of resistors
B. it results in high power dissipation
C. high noise creation
D. it uses minimum number of transistors
Answer» B. it results in high power dissipation
24.

TTL circuits with “totem-pole” output stage minimize  

A. the power dissipation in rtl
B. the time consumption in rtl
C. the speed of transferring rate in rtl
D. propagation delay in rtl
Answer» A. the power dissipation in rtl
25.

The minimum number of transistors can be used by 2 input AND gate is                      

A. 2
B. 3
C. 4
D. 5
Answer» A. 2
26.

Diode–transistor logic (DTL) is the direct ancestor of                            

A. register-transistor logic
B. transistor–transistor logic
C. high threshold logic
D. emitter coupled logic
Answer» B. transistor–transistor logic
27.

In DTL logic gating function is performed by                        

A. diode
B. transistor
C. inductor
D. capacitor
Answer» A. diode
28.

In DTL amplifying function is performed by                        

A. diode
B. transistor
C. inductor
D. capacitor
Answer» B. transistor
29.

How many stages a DTL consist of?

A. 2
B. 3
C. 4
D. 5
Answer» B. 3
30.

The full form of CTDL is                        

A. complemented transistor diode logic
B. complemented transistor direct logic
C. complementary transistor diode logic
D. complementary transistor direct logic
Answer» A. complemented transistor diode logic
31.

The DTL propagation delay is relatively                        

A. large
B. small
C. moderate
D. negligible
Answer» A. large
32.

The way to speed up DTL is to add an across intermediate resister is                        

A. small “speed-up” capacitor
B. large “speed-up” capacitor
C. small “speed-up” transistor
D. large ” speed-up” transistor
Answer» A. small “speed-up” capacitor
33.

The process to avoid saturating the switching transistor is performed by                        

A. baker clamp
B. james r. biard
C. chris brown
D. totem-pole
Answer» A. baker clamp
34.

A major advantage of DTL over the earlier resistor–transistor logic is the                        

A. increased fan out
B. increased fan in
C. decreased fan out
D. decreased fan in
Answer» B. increased fan in
35.

To increase fan-out of the gate in DTL                        

A. an additional capacitor may be used
B. an additional resister may be used
C. an additional transistor and diode may be used
D. only an additional diode may be used
Answer» C. an additional transistor and diode may be used
36.

A disadvantage of DTL is                        

A. the input transistor to the resister
B. the input resister to the transistor
C. the increased fan-in
D. the increased fan-out
Answer» B. the input resister to the transistor
37.

Compatibility refers to                          

A. the output of a circuit should match with the input of another circuit
B. the output of a circuit should match with the input of the same circuit
C. the input of a circuit should match with the output of another circuit
D. the input of a circuit should match with the output of same circuit
Answer» A. the output of a circuit should match with the input of another circuit
38.

The method of connecting a driving device to a loading device is known as                        

A. compatibility
B. interface
C. sourcing
D. sinking
Answer» B. interface
39.

The first CML logic was introduced by General Electric in                        

A. 1960
B. 1981
C. 1961
D. 1990
Answer» C. 1961
40.

Schottky families prevent the saturating using                        

A. transistors
B. schottky transistors
C. diodes
D. schottky diodes
Answer» D. schottky diodes
41.

The basic idea of basic CML circuit came from an                        

A. inverter
B. buffer
C. transistor
D. both inverter and buffer
Answer» D. both inverter and buffer
42.

The full form of MECL is                        

A. mono emitter coupled logic
B. motorola emitter coupled logic
C. motorola emitter capacitor logic
D. both mono emitter and motorola coupled logic
Answer» B. motorola emitter coupled logic
43.

Motorola has offered MECL circuits in logic families.

A. 3
B. 4
C. 5
D. 6
Answer» C. 5
44.

The latest entrant to the ECL family is                        

A. ecl 10k
B. ecl 100k
C. ecl 1000k
D. ecl 10000k
Answer» B. ecl 100k
45.

All input of NOR as low produces result as                        

A. low
B. mid
C. high
D. high impedance
Answer» C. high
46.

In RTL NOR gate, the output is at logic 1 only when all the inputs are at                        

A. logic 0
B. logic 1
C. +10v
D. floating
Answer» A. logic 0
47.

The full form of CMOS is                          

A. capacitive metal oxide semiconductor
B. capacitive metallic oxide semiconductor
C. complementary metal oxide semiconductor
D. complemented metal oxide semiconductor
Answer» C. complementary metal oxide semiconductor
48.

The full form of COS-MOS is                          

A. complementary symmetry metal oxide semiconductor
B. complementary systematic metal oxide semiconductor
C. capacitive symmetry metal oxide semiconductor
D. complemented systematic metal oxide semiconductor
Answer» A. complementary symmetry metal oxide semiconductor
49.

CMOS is also sometimes referred to as                          

A. capacitive metal oxide semiconductor
B. capacitive symmetry metal oxide semiconductor
C. complementary symmetry metal oxide semiconductor
D. complemented symmetry metal oxide semiconductor
Answer» C. complementary symmetry metal oxide semiconductor
50.

CMOS technology is used in                          

A. inverter
B. microprocessor
C. digital logic
D. both microprocessor and digital logic
Answer» D. both microprocessor and digital logic
51.

Two important characteristics of CMOS devices are                          

A. high noise immunity
B. low static power consumption
C. high resistivity
D. both high noise immunity and low static power consumption
Answer» D. both high noise immunity and low static power consumption
52.

CMOS behaves as a/an                          

A. adder
B. subtractor
C. inverter
D. comparator
Answer» C. inverter
53.

An important characteristic of a CMOS circuit is the                          

A. noise immunity
B. duality
C. symmetricity
D. noise margin
Answer» B. duality
54.

CMOS logic dissipates power than NMOS logic circuits.

A. more
B. less
C. equal
D. very high
Answer» B. less
55.

Semiconductors are made of                          

A. ge and si
B. si and pb
C. ge and pb
D. pb and au
Answer» A. ge and si
56.

Which chip were the first RTC and CMOS RAM chip to be used in early IBM computers, capable of storing a total of 64 bytes?

A. the samsung 146818
B. the samsung 146819
C. the motorola 146818
D. the motorola 146819
Answer» C. the motorola 146818
57.

The full form of ECL is                      

A. emitter-collector logic
B. emitter-complementary logic
C. emitter-coupled logic
D. emitter-cored logic
Answer» C. emitter-coupled logic
58.

Which logic is the fastest of all the logic families?

A. ttl
B. ecl
C. htl
D. dtl
Answer» B. ecl
59.

Sometimes ECL can also be named as                      

A. eel
B. cel
C. cml
D. ccl
Answer» C. cml
60.

In an ECL the output is taken from                      

A. emitter
B. base
C. collector
D. junction of emitter and base
Answer» C. collector
61.

The ECL behaves as                      

A. not gate
B. nor gate
C. nand gate
D. and gate
Answer» B. nor gate
62.

In ECL the fanout capability is                      

A. high
B. low
C. zero
D. sometimes high and sometimes low
Answer» A. high
63.

ECL’s major disadvantage is that  

A. it requires more power
B. it’s fanout capability is high
C. it creates more noise
D. it is slow
Answer» A. it requires more power
64.

The full form of SCFL is                      

A. source-collector logic
B. source-coupled logic
C. source-complementary logic
D. source cored logic
Answer» B. source-coupled logic
65.

The equivalent of emitter-coupled logic made out of FETs is called                      

A. cml
B. scfl
C. fecl
D. efcl
Answer» B. scfl
66.

ECL was invented in by                      

A. 1956, baker clamp
B. 1976, james r. biard
C. 1956, hannon s. yourke
D. 1976, yourke
Answer» C. 1956, hannon s. yourke
67.

At the time of invention, an ECL was called as                      

A. source-coupled logic
B. current mode logic
C. current-steering logic
D. emitter-coupled logic
Answer» C. current-steering logic
68.

The ECL circuits usually operates with                      

A. negative voltage
B. positive voltage
C. grounded voltage
D. high voltage
Answer» A. negative voltage
69.

Low-voltage positive emitter-coupled logic (LVPECL) is a power optimized version of

A. ecl
B. vecl
C. pecl
D. lecl
Answer» C. pecl
70.

Transistor–transistor logic (TTL) is a class of digital circuits built from                          

A. jfet only
B. bipolar junction transistors (bjt)
C. resistors
D. bipolar junction transistors (bjt) and resistors
Answer» D. bipolar junction transistors (bjt) and resistors
71.

TTL was invented in 1961 by                          

A. baker clamp
B. james l. buie
C. chris brown
D. frank wanlass
Answer» B. james l. buie
72.

The full form of TCTL is                          

A. transistor-coupled transistor logic
B. transistor-capacitor transistor logic
C. transistor-complemented transistor logic
D. transistor-complementary transistor logic
Answer» A. transistor-coupled transistor logic
73.

The ancestor to the first personal computers.

A. param 1
B. satyam 1
C. kenbak 1
D. mits altair
Answer» C. kenbak 1
74.

TTL inputs are the emitters of a                          

A. transistor-transistor logic
B. multiple-emitter transistor
C. resistor-transistor logic
D. diode-transistor logic
Answer» B. multiple-emitter transistor
75.

TTL is a                          

A. current sinking
B. current sourcing
C. voltage sinking
D. voltage sourcing
Answer» A. current sinking
76.

Standard TTL circuits operate with a volt power supply.

A. 2
B. 4
C. 5
D. 3
Answer» C. 5
77.

A TTL gate may operate inadvertently as an                          

A. digital amplifier
B. analog amplifier
C. inverter
D. regulator
Answer» B. analog amplifier
78.

Which statement below best describes a Karnaugh map?

A. it is simply a rearranged truth table
B. the karnaugh map eliminates the need for using nand and nor gates
C. variable complements can be eliminated by using karnaugh maps
D. a karnaugh map can be used to replace boolean rules
Answer» A. it is simply a rearranged truth table
79.

Which of the examples below expresses the commutative law of multiplication?

A. a + b = b + a
B. a • b = b + a
C. a • (b • c) = (a • b) • c
D. a • b = b • a
Answer» D. a • b = b • a
80.

The Boolean expression Y = (AB)’ is logically equivalent to what single gate?

A. nand
B. nor
C. and
D. or
Answer» A. nand
81.

The systematic reduction of logic circuits is accomplished by:

A. symbolic reduction
B. ttl logic
C. using boolean algebra
D. using a truth table
Answer» C. using boolean algebra
82.

Each “1” entry in a K-map square represents:

A. a high for each input truth table condition that produces a high output
B. a high output on the truth table for all low input combinations
C. a low output for all possible high input conditions
D. a don’t care condition for all possible input truth table combinations
Answer» A. a high for each input truth table condition that produces a high output
83.

Each “0” entry in a K-map square represents:

A. a high for each input truth table condition that produces a high output
B. a high output on the truth table for all low input combinations
C. a low output for all possible high input conditions
D. a don’t care condition for all possible input truth table combinations
Answer» A. a high for each input truth table condition that produces a high output
84.

Looping on a K-map always results in the elimination of                      

A. variables within the loop that appear only in their complemented form
B. variables that remain unchanged within the loop
C. variables within the loop that appear in both complemented and uncomplemented form
D. variables within the loop that appear only in their uncomplemented form
Answer» C. variables within the loop that appear in both complemented and uncomplemented form
85.

Which of the following expressions is in the sum-of-products form?

A. (a + b)(c + d)
B. (a * b)(c * d)
C. a* b *(cd)
D. a * b + c * d
Answer» D. a * b + c * d
86.

What is an ambiguous condition in a NAND based S’-R’ latch?

A. s’=0, r’=1
B. s’=1, r’=0
C. s’=1, r’=1
D. s’=0, r’=0
Answer» D. s’=0, r’=0
87.

In a NAND based S’-R’ latch, if S’=1 & R’=1 then the state of the latch is

A. no change
B. set
C. reset
D. forbidden
Answer» A. no change
88.

A NAND based S’-R’ latch can be converted into S-R latch by placing                          

A. a d latch at each of its input
B. an inverter at each of its input
C. it can never be converted
D. both a d latch and an inverter at its input
Answer» D. both a d latch and an inverter at its input
89.

The difference between a flip-flop & latch is                          

A. both are same
B. flip-flop consist of an extra output
C. latches has one input but flip-flop has two
D. latch has two inputs but flip-flop has one
Answer» C. latches has one input but flip-flop has two
90.

How many types of flip-flops are?

A. 2
B. 3
C. 4
D. 5
Answer» C. 4
91.

The S-R flip flop consist of                          

A. 4 and gates
B. two additional and gates
C. an additional clock input
D. 3 and gates
Answer» B. two additional and gates
92.

What is one disadvantage of an S-R flip-flop?

A. it has no enable input
B. it has a race condition
C. it has no clock input
D. invalid state
Answer» D. invalid state
93.

One example of the use of an S-R flip-flop is as                          

A. racer
B. stable oscillator
C. binary storage register
D. transition pulse generator
Answer» C. binary storage register
94.

When is a flip-flop said to be transparent?

A. when the q output is opposite the input
B. when the q output follows the input
C. when you can see through the ic packaging
D. when the q output is complementary of the input
Answer» B. when the q output follows the input
95.

On a positive edge-triggered S-R flip-flop, the outputs reflect the input condition when

A. the clock pulse is low
B. the clock pulse is high
C. the clock pulse transitions from low to high
D. the clock pulse transitions from high to low
Answer» C. the clock pulse transitions from low to high
96.

What is the hold condition of a flip-flop?

A. both s and r inputs activated
B. no active s or r input
C. only s is active
D. only r is active
Answer» B. no active s or r input
97.

One example of the use of an S-R flip-flop is as                        

A. transition pulse generator
B. racer
C. switch debouncer
D. astable oscillator
Answer» C. switch debouncer
98.

The truth table for an S-R flip-flop has how many VALID entries?

A. 1
B. 2
C. 3
D. 4
Answer» C. 3
99.

When both inputs of a J-K flip-flop cycle, the output will                        

A. be invalid
B. change
C. not change
D. toggle
Answer» C. not change
100.

Which of the following is correct for a gated D-type flip-flop?

A. the q output is either set or reset as soon as the d input goes high or low
B. the output complement follows the input when enabled
C. only one of the inputs can be high at a time
D. the output toggles if one of the inputs is held high
Answer» A. the q output is either set or reset as soon as the d input goes high or low
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