LCST

Question 1

RAM is also known as _____

A. RWM
B. MAR
C. ROM
D. MBR

Answer 1

A. RWM

A Random Access Memory (RAM) is a volatile chip memory in which both the read and write operations can be performed.
Since it is volatile, therefore
it stores data as long as power is on.
RAM is also known as RWM (i.e. Read
Write Memory).

Question 2

The symbol shown is for what type of
logic gate?

(LCST FIGURE)

A. NAND
B. AND
C. OR
D. NOR

Answer 2

C. OR

Question 3

Which of the following expressions
represents the Boolean Law of
Absorption?

A. X+X=X
B. X+O=X
C. X·1=X
D. X+XY=X

Answer 3

D. X+XY=X

(LCST FIGURE)

Question 4

A two input MUX would have _____

A. 4 select lines
B. 3 select lines
C. 1 select line
D. 2 select lines

Answer 4

C. 1 select line

The two input multiplexer would have n
select lines in 2^n. Thus n = 1.
Therefore, it has 1 select line.

Question 5

Which combinational circuit is
renowned for selecting a single input
from multiple inputs & directing the
binary information to output line?

A. Both data selector and data distributor
B. DeMultiplexer
C. Data distributor
D. Data Selector

Answer 5

D. Data Selector

Data Selector is another name of
Multiplexer. A multiplexer (or MUX) is a
device that selects one of several
analog or digital input signals and
forwards the selected input into a single
line, depending on the active select
lines.

Question 6

UP-DOWN counter is also known as _____

A. Two Counter
B. Multimode counter
C. Multi counter
D. Dual counter

Answer 6

B. Multimode counter

UP-DOWN counter is also known as
multimode counter because it has
capability of counting upward as well as
downwards.

Question 7

A register is defined as _____

A. The group of latches for storing n-bit of
information
B. The group of flip-flops suitable for
storing binary information
C. The group of flip-flops suitable for storing
one bit of information
D. The group of latches for storing one bit of
information

Answer 7

B. The group of flip-flops suitable for
storing binary information

A register is defined as the group of flip-
flops suitable for storing binary
information. Each flip-flop is a binary
cell capable of storing one bit of
information. The data in a register can
be transferred from one flip-flop to
another.

Question 8

For the electrical symbol illustrated
below to represent “1” as it’s output, the
inputs must be:

(LCST FIGURE)

A. one input “1” the other “O”
B. both inputs “o”
C. the top input “0”, the bottom input “1”
D. both inputs “1”

Answer 8

B. both inputs “o”

(LCST FIGURE)

Question 9

The nominal value of the dc supply
voltage for TTL and CMOS is _____

A. +9V
B. +3V
C. +12V
D. +5V

Answer 9

D. +5V

The nominal value of the dc supply
voltage for TTL and CMOS is +5V.

Question 10

In multiplexer circuits, the enable input
is also known as _____

A. Strobe
B. Sink
C. Decoded input
D. Select input

Answer 10

A. Strobe

The enable input is also known as
strobe which is used to cascade two or
more multiplexer ICs to construct a
multiplexer with a larger number of
inputs. Enable input activates the
multiplexer to operate.

Question 11

The main difference between a register
and a counter is.

A. A counter has no specific sequence of
states
B. A register has capability to store one bit of
information but counter has n-bit
C. A register has no specific sequence of
states
D. A register counts data

Answer 11

C. A register has no specific sequence of
states

The main difference between a register and a counter is that a register has no specific sequence of states except in certain specialised applications.

Question 12

The electrical symbol illustrated below
represents an:

(LCST FIGURE)

A. NOT Gate
B. NOR Gate
C. OP-AMP
D. OR gate

Answer 12

B. NOR Gate

An NOR Gate is the combination of both
an OR gate and a NOT Gate

Question 13

A combinational circuit is one in which
the output depends on the _____

A. Input combination and the previous output
B. Input combination at that time and the
previous input combination
C. Input combination at the time
D. Present output and the previous

Answer 13

C. Input combination at the time

A combinational circuit is one in which
the output depends on the input
combination at the time, whereas, a
sequential circuit is one in which the
output depends on present input as well
past outputs

Question 14

Most demultiplexers facilitate which
type of conversion?

A. AC to DC
B. Odd parity to even parity
C. Decimal-to-hexadecimal
D. Single input, multiple outputs

Answer 14

D. Single input, multiple outputs

A demultiplexer sends a single input to
multiple outputs, depending on the
select lines. Demultiplexer converts
single input into multiple outputs.

Question 15

The terminal count of a typical
modulus-10 binary counter is

A. 1111
B. 1001
C. 0000
D. 1010

Answer 15

B. 1001

A binary counter counts or produces the equivalent binary number depending on the cycles of the clock input.
Modulus-10 means count from 0 to 9.
So, terminal count is 9(1001).

Question 16

How many inputs are required for a 1-
of-16 decoder?

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

Answer 16

C. 4

A binary decoder is a combinationa logic circuit which decodes binary information from n-inputs to a maximum of 2 outputs. Here, number of
outputs = 16.16 =2= 2. Thus, number
of inputs is 4.

Question 17

A procedure that specifies finite set of
steps is called _____

A. Venn diagram
B. Flow chart
C. Algorithm
D. Chart

Answer 17

C. Algorithm

A procedure that specifies finite set of
steps is called algorithm, while a
flowchart is a pictorial representation of
the algorithm.

Question 18

DeMorgan’s theorem states that

A. None of these choices
B. A’+B’= A’B
C. (AB)’= A’ + B’
D (A+ B)’=A’B

Answer 18

C. (AB)’= A’ + B’

The DeMorgan’s law states that
(AB)’ = A’+B’&(A+B)’=A’*B’.

Question 19

How many NAND circuits are contained
in a 7400 NAND IC?

A. 4
B. 8
C. 1
D. 2

Answer 19

A. 4

7400 IC’s pin has total 14 pin. Pin no 7
use for GND and pin no 14 used for
+vcc and remaining pins used for
connections. For a NAND gate two
inputs are required and one output is obtained means for NAND gate 3 pin connections are required.

Question 20

Any signed negative binary number is
recognised by its _____

A. LSB
B. Nibble
C. Byte
D. MSB

Answer 20

D. MSB

Any negative number is recognized by its MSB (Most Significant Bit). If it’s 1,then it’s negative, else if it’s 0, then
positive.

Question 21

A single transistor can be used to build
which of the following digital logic
gates?

A. NAND gate
B. OR gate
C. NOT gate
D. AND gate

Answer 21

C. NOT gate

A transistor can be used as a switch.
That is, when base is low collector is
high (input zero, output one) and base is
high collector is low (input 1, output 0).

Question 22

Which is not an output state for tristate
logic?

A. High-Z
B. LOW
C. Low-Z
D. HIGH

Answer 22

C. Low-Z

Question 23

The difference between a flip-flop &
latch is _____

A. Latch has two inputs but flip-flop has one
B. Both are same
C. Flip-flop consist of an extra output
D. Latches has one input but flip-flop has
two

Answer 23

D. Latches has one input but flip-flop has
two

Flip-flop is a modified version of latch.To determine the changes in states, an additional control input is provided to the latch.

Question 24

Number of outputs in a half adder _____

A. 2
B. 3
C. 0
D. 1

Answer 24

A. 2

A half adder gives two outputs. One is called the sum and the other is carry.Half adder can be implemented using an EXOR gate and an AND gate.

Question 25

MSI includes _____ gates per chip. A. 13 to 50 B. None of these choices C. greater than 10 D. 12 to 100

Answer 25

D. 12 to 100 Medium Scale Integration includes 12 to 100 gates per chip.

Question 26

The parameter through which 16 distinct values can be represented is known as. A. Bit B. Word C. Byte D. Nibble

Answer 26

B. Word It can be represented up to 16 different values with the help of a Word. Nibble is a combination of four bits and Byte is a combination of 8 bits. It is "word" which is said to be a collection of 16-bits on most of the systems.

Question 27

In a multiplexer the output depends on its _____ A. Select inputs B. Enable pin C. Data inputs D. Select outputs

Answer 27

A. Select inputs A demultiplexer sends a single input to multiple outputs, depending on the select lines. As the select input changes, the output of the multiplexer varies according to that input.

Question 28

Which is not an example of a truncated modulus? A. 9 B. 15 C. 8 D. 11

Answer 28

C. 8 An n-bit counter whose modulus is less than the maximum possible is called a truncated counter. Here, 9, 11 and 15 modulus counters are truncated counters. Whereas, modulus-8 is not a truncated counter.

Question 29

The symbol shown is for what type of logic gate? (1) (LCST FIGURE) A. AND B. NOR C. NAND D. OR

Answer 29

C. NAND

Question 30

The Boolean expression X O. Y is for.. A. XOR B. AND C. OR D. XNOR

Answer 30

D. XNOR XOR: Xθ Y XNOR: XOY OR: X+Y AND: XY or X·Y (LCST FIGURE)

Question 31

The device shown here is most likely a (LCST FIGURE) A. Demultiplexer B. Comparator C. Inverter D. Multiplexer

Answer 31

A. Demultiplexer The given diagram is demultiplexer, because it takes single input & gives many outputs. A demultiplexer is a combinational circuit that takes a single output and latches it to multiple outputs depending on the select lines.

Question 32

The expression: A + Ā = 1indicates .. A. commutative law B. idempotent law C. absorption law D. complement law

Answer 32

D. complement law

Question 33

A full adder logic circuit will have A. Two inputs and two outputs B. Three inputs and three C. Three inputs and two outputs D. Two inputs and one output

Answer 33

D. Two inputs and one output A full adder circuit will add two bits and it will also accounts the carry input generated in the previous stage. Thus three inputs and two outputs (Sum and Carry) are there. In case of half adder circuit, there are only two inputs bits and two outputs (SUM and CARRY).

Question 34

What is a multiplexer? A. A multiplexer is a device which converts many signals into one B. It takes one input and results into many output C. It is a type of decoder which decodes several inputs and gives one output D. It is a type of encoder which decodes several inputs and gives one output

Answer 34

A. A multiplexer is a device which converts many signals into one A multiplexer (or MUX) is a device that selects one of several analog or digital input signals and forwards the selected input into a single line, depending on the active select lines.

Question 35

If the decimal number is a fraction then its binary equivalent is obtained by _____ the number continuously by 2. A. Adding B. Subtracting C. Multiplying D. Dividing

Answer 35

C. Multiplying On multiplying the decimal number continuously by 2, the binary equivalent is obtained by the collection of the integer part. However, if it's an integer, then it's binary equivalent is determined by dividing the number by 2 and collecting the remainders.

Question 36

Exclusive-OR (XOR) logic gates can be constructed from what other logic gates? A. AND gates and NOT gates B. OR gates and NOT gates C. AND gates, OR gates, and NOT gates D. OR gates only

Answer 36

C. AND gates, OR gates, and NOT gates Expression for XOR is: A(B')+(A')B So in the above expression, the following logic gates are used: AND, OR, NOT. Thus, 2 AND gates with two-inputs and 1 OR gate with two-inputs will be required for constructing a XOR gate.

Question 37

A register is a type of _____ A. Combinational circuit B. Sequential circuit C. 1/0 device D. analog circuit

Answer 37

B. Sequential circuit Register's output depends on the past and present states of the inputs. The device which follows these properties is termed as a sequential circuit. Whereas,combinational circuits only depend on the present values of inputs.

Question 38

Why are ROMs called non-volatile memory? A. They do not lose memory when power is supplied B. They lose memory when power is supplied C. They lose memory when power is removed D. They do not lose memory when power is removed

Answer 38

D. They do not lose memory when power is removed ROMs are called non-volatile memory because of they do not lose memory when power is removed

Question 39

What is the minimum number of two input NAND gates used to perform the function of two input OR gates? A. Four B. One C. Two D. Three

Answer 39

D. Three (LCST FIGURE)

Question 40

How many AND gates are required for a 1-to-8 multiplexer? A. 6 B. 2 C. 8 D. 5

Answer 40

C. 8 The number of AND gates required will be equal to the number of outputs in a demultiplexer, which are 8.

Question 41

A basic S-R flip-flop can be constructed by cross-coupling of which basic logic gates? A. XOR or XNOR gates B. AND or NOR gates C. NOR or NAND gates D. AND or OR gates

Answer 41

C. NOR or NAND gates The basic S-R flip-flop can be constructed by cross coupling of NOR or NAND gates. Cross coupling means the output of second gate is fed to the input of first gate and vice-versa.

Question 42

How many outputs will a decimal-to- BCD encoder have? A. 16 B. 8 C. 4 D. 12

Answer 42

C. 4 An encoder is a combinational circuit encoding the information of 2 input lines to n output lines, thus producing the binary equivalent of the input. Thus,a decimal to BCD encoder has 4 outputs.

Question 43

Which of the following is an incorrect SOP expression? A. x+y B. (x+y)(x+z) C. X+x.y D. ×

Answer 43

B. (x+y)(x+z) The second expression is incorrect because it consists of two maxterms ANDed together. This makes it a POS or the product of sum expression.

Question 44

A variable on its own or in its complemented form is known as a A. Sum Term B. Word C. Product Term D. Literal

Answer 44

D. Literal A literal is a single logic variable or its complement. For example-X,Y, A,Z,X' etc.

Question 45

What are the major differences between the 5400 and 7400 series of ICs? A. The 5400 series are military grade and allow for a wider range of supply voltages and temperatures B. The 5400 series are military grade and require tighter supply voltages and temperatures C. The 7400 series was originally developed by Texas Instruments and the 5400 series was brought out by National Semiconductors after TI's patents expired as a second supply sour D. The 7400 series are an improvement over the original 5400s

Answer 45

A. The 5400 series are military grade and allow for a wider range of supply voltages and temperatures The 5400 series are military grade and allow for a wider range of supply voltages and temperatures, these are the major differences between the 5400 and 7400 series of ICs

Question 46

Which ROM can be erased by an electrical signal? A. Mask ROM B. EPROM C. ROM D. EEPROM

Answer 46

D. EEPROM EEPROMs (Electrically Erased Programmable ROM) can be erased by an electrical signal.

Question 47

Based on how binary information is entered or shifted out, shift registers are classified into _____ categories. A. 3 B. 5 C. 4 D. 2

Answer 47

C. 4 The registers in which data can be shifted serially or parallelly are known as shift registers. Based on how binary information is entered or shifted out, shift registers are classified into 4 categories, viz., Serial-In/Serial- Out(SISO), Serial-In/Parallel-Out (SIPO),Parallel-In/Serial-Out (PISO), Parallel-In/Parallel-Out (PIPO).

Question 48

What is the difference between a ring shift counter and a Johnson shift counter? A. There is no difference B. A ring is faster C. The Johnson is faster D. The feedback is reversed

Answer 48

D. The feedback is reversed A ring counter is a shift register (a cascade connection of flip-flops) with the output of the last one connected to the input of the first, that is, in a ring. Whereas, a Johnson counter (or switchtail ring counter, twisted-ring counter, walking-ring counter, or Moebius counter) is a modified ring counter, where the output from the last stage is inverted and fed back as input to the first stage.

Question 49

In 1-to-4 demultiplexer, how many select lines are required? A. 2 B. 4 C. 5 D. 3

Answer 49

A. 2 The formula for total no. of outputs is given by 2, where n is the no. of select lines. Therefore, for 1:4 demultiplexer, 2 select lines are required.

Question 50

Which of the following logic families has the highest maximum clock frequency? A. AS-TTL B. HCMOS C. S-TTL D. HS-TTL

Answer 50

A. AS-TTL AS-TTL (Advanced Schottky) has a maximum clock frequency of 105 MHz. S-TTL (Schottky High Speed TTL) has 100 MHz. Found nothing as HS-TTL. There are H and S separate TTL. HCMOS has 50 MHz clock frequency.

Question 51

A Karnaugh map (K-map) is an abstract form of _____ diagram organized as a matrix of squares. A. Venn Diagram B. Block diagram C. Triangular Diagram D. Cycle Diagram

Answer 51

A. Venn Diagram A Karnaugh map (K-map) is an abstract form of Venn diagram organized as a matrix of squares, where each square represents a Maxterm or a Minterm.

Question 52

What is the minimum number of two input NAND gates used to perform the function of a NOT gate? A. Four B. Two C. One D. Three

Answer 52

C. One

Question 53

Which of the following expressions represents the Idempotent Law of Boolean Algebra? A. X+XY=X B. X+0=0 C. X+1=1 D. X+X=X

Answer 53

D. X+X=X

Question 54

The Boolean expression X θ Y is for... A. AND B. XNOR C. XOR D. OR

Answer 54

C. XOR

Question 55

In boolean algebra, the OR operation is performed by which properties? A. Distributive properties B. All of these choices C. Associative properties D. Commutative properties

Answer 55

B. All of these choices The expression for Associative property is given by A+(B+C) = (A+B)+C & A*(B*C) = (A*B)*C. The expression for Commutative property is given by A+B = B+A &A*B = B*A. The expression for Distributive property is given by A+BC = (A+B)(A+C) & A(B+C) = AB+AC.

Question 56

The gates required to build a half adder are. A. EX-OR gate and NOR gate B. EX-OR gate and OR gate C. EX-NOR gate and AND gate D. EX-OR gate and AND gate

Answer 56

D. EX-OR gate and AND gate The gates required to build a half adder are EX-OR gate and AND gate. EX-OR outputs the SUM of the two input bits whereas AND outputs the CARRY of the two input bits.

Question 57

Ring and Johnson counters are A. Synchronous and true binary counters B. Asynchronous counters C. True binary counters D. Synchronous counters

Answer 57

D. Synchronous counters Synchronous counters are the counters being triggered in the presence of a clock pulse. Since, all of the clock inputs are connected through a single clock pulse in ring shift and Johnson counters. So, both are synchronous counters.

Question 58

The expression for involution law is _____ A. (x)x=x B. X+1=1 C. x+y=y+X D. (x)'=x

Answer 58

D. (x)'=x The involution law states that the complement of complement of a number is the number itself. The third option justifies the statement. Thus, (×)'=x.

Question 59

1's complement can be easily obtained by using _____ A. Adder B. Comparator C. Subtractor D. Inverter

Answer 59

D. Inverter With the help of inverter the 1's complement is easily obtained. Since, during the operation of 1's complement 1 is converted into 0 and vice-versa and this is well suited for the inverter.

Question 60

Which of following are known as universal gates? A. XOR &OR B. None of these choices C. AND & OR D. NAND & NOR

Answer 60

D. NAND & NOR The NAND & NOR gates are known as universal gates because any logic circuit can be realized completely by using either of these two gates.

Question 61

All computer programs for a machine are called: A. hardware B. none of these choices C. software D. input

Answer 61

C. software Computer hardware is any physical device used in or with your machine,whereas software is a collection of programming code installed on your computer's hard drive.