# Unit 1 (DE)

# Theory

### Quiz

The OR operation is performed by which property in Boolean algebra?

Associative properties

Commutative properties

Distributive properties

All of the mentioned

**All of the mentioned**

The Boolean expression X = (A +B)(C+D) represents

Two ORs ANDed together

Two ANDs ORed together

A 4- input OR gate

A 4- input AND gate

F(X,Y,Z) = X`Y`

Z`. The degree of the function is *__*

3

5

4

1

***pending**

Complement of the expression A’B + CD’ is *_*

(A’ + B)(C’ + D)

(A’ + B)(C’ + D’)

(A + B’)(C’ + D)

(A + B’)(C+ D’)

**(A + B’)(C’ + D)**

The binary equivalent of 28 is

11100

11101

10100

111001

**11100**

# Practical

## 1.1

If a signal passing through a gate is inhibited by sending a low into one of the inputs, and the output is HIGH, then what kind of gate satisfies the given condition?

NAND

NOT

OR

AND

**NAND**

The logic gate that will have HIGH or “1” at its output when any one of its inputs is HIGH is a:

OR

AND

NOR

NOT

**OR**

How many NAND circuits are contained in an HD74LS00 NAND gate IC?

4

6

2

3

**4**

NOT gate is used as an inverter.

True

False

**True**

Choose the odd one out

Watch

Calculator

Computer

Coal

**Coal**

Boolean expression for XNOR gate is

AB + A’B’

AB

A’B’

AB’ + A’B

**AB + A’B’**

What are the advantages of the digital systems?

High-efficiency

Uses less bandwidth

Encryption

All of the above

**All of the above**

How many possibilities does two-bit number have?

2

3

4

8

**4**

The boolean algebra is given by *_*

George Boole

Pascal

Ronald J Tocci

None of the above

**George Boole**

All real-life signals are ** __** in nature

Digital

Analog

Discrete

None of the above

**Analog**

## 1.2

How many pins does temperature sensor have?

3

2

1

4

**3**

What is the relation of temperature to resistance in LM35?

linear at 10mv

rising exponential

declining exponential

no effect

***PENDING**

The logical product of two or more than two logical sums is termed as

OR operation

POS

SOP

NAND operation

**POS**

What are the complements used for subtraction?

Binary subtraction

Hexadecimal subtraction

BCD & Excess-3 subtraction

All of the above

**All of the above**

The Karnaugh map is developed in which year?

1951

1952

1953

1954

**1953**

What is the output of the temperature sensor?

Temperature

Resistance proportional to the instantaneous temperature

Analog signal proportional to the instantaneous temperature

None of the above

**Analog signal proportional to the instantaneous temperature**

Who invented Gray code?

Frank Gray

Dom Hofmann

Aryabhatta

None of the above

**Frank Gray**

**__** is used in communication process to minimize the effect of noise.

Digital signal

Analog signal

Electrical signal

None of the above

**Digital signal**

## 1.3

Exclusive-OR (XOR) logic gates can be constructed from ………..logic gates.

OR gates only

AND gates and NOT gates

AND gates, OR gates, and NOT gates

OR gates and NOT gate

**AND gates, OR gates, and NOT gates**

……….. truth table entries are necessary for a four-input circuit.

4

8

12

16

**16**

A radix K number system requires how many different symbols to represent the digits 0 to K – 1?

K

K-1

K+1

1

**K**

Both OR and AND gates can have only 2 inputs.

True

False

**False**

……….. input values will cause an AND logic gate to produce a HIGH output.

At least one input is HIGH

At least one input is LOW

All inputs are HIGH

All inputs are LOW

**All inputs are HIGH**

OR operation is achieved through a NAD gate with additional..

AND gate

OR gate

XOR gate

Inverters

**XOR gate**

The inputs of a NAND gate are connected together. The resulting circuit is ………….

OR gate

AND gate

NOT gate

None of the above

**NOT gate**

The only function of NOT gate is to ……………..

Stop signal

Invert input signal

Act as a universal gate

None of the above

**Invert input signal**

An OR gate has 4 inputs. One input is high and the other three are low. The output is …….

Low

High

Alternately high and low

May be high or low depending on relative magnitude of inputs

**High**

A single transistor can be used to build ………….. gates .

OR Gate

NOT Gate

AND Gate

NAND Gate

## 1.4

The K-map based Boolean reduction is based on the following Unifying Theorem: A + A’ = 1.

Impact

Non Impact

Force

Complementarity

**Non Impact**

Product-of-Sums expressions can be implemented using **_**

2-level OR-AND logic circuits

2-level NOR logic circuits

2-level XOR logic circuits

Both 2-level OR-AND and NOR logic circuits

**Both 2-level OR-AND and NOR logic circuits**

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

NAND

NOR

AND

OR

**NAND**

Four adjacent ‘1’s in a Karnaugh map forms a_______ .

octet

singlet

pair

quad

**quad**

Each group of adjacent Minterms (group size in powers of twos) corresponds to a possible product term of the given **_**

Function

Value

Set

Word

**Function**

If n denotes the number of variable then the number of cells are given as

2n

2+n

2-n

2 to the power of n

**2 to the power of n**

Using the transformation method you can realize any POS realization of OR-AND with only.

XOR

NAND

AND

NOR

**NOR**

The prime implicant which has at least one element that is not present in any other implicant is known as **_**

Essential Prime Implicant

Implicant

Complement

Prime Complement

**Essential Prime Implicant**

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

A HIGH for each input truth table condition that produces a HIGH output

A HIGH output on the truth table for all LOW input combinations

A LOW output for all possible HIGH input conditions

DON’T CARE condition for all possible input truth table combinations

**A HIGH for each input truth table condition that produces a HIGH output**

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

(A + B)(C + D)

(A * B)(C * D)

A* B *(CD)

A * B + C * D

**A * B + C * D**