In this article, we are going to see **basic** to **advanced Digital Logic Interview Questions** and **Answers**. **digital logic** basically deals with how we can represent the numerical value of quantities like analog and digital.

#### Digital systems are the systems which

- deal with digital information in the external world
- use analog signals
- manipulate information
- handle information in digital form internally

**Answer - (4) handle information in digital form internally**

#### Analog systems are different form digital systems because

- they use transistors
- they handle information in analog form
- they handle information in digital form
- they are slow

**Answer - (2) they handle information in analog form**

#### Why are digital circuits easie to design then analog circuits?

- They do not control electricity precisely over a wide range.
- They are made in the form of ICs.
- All elements of digital circuits are from the same family.
- They are smaller in size.

**Answer - (1) They do not control electricity precisely over a wide range**

#### A digital gate can respond to an input signal in

- about a second
- about a hundreadth of a second
- a few billionth of a second
- a few millisecond

**Answer - (3) a few billionths of a second**

#### Analog methods are not used for handling extremly precise information because

- precise information always involves numbers which are inherently digital
- there are limits to how closely an analog signal can reproduce the information
- analog information never need to be precise
- they are very expensive

**Answer - (2) there are limits to how closely an analog signal can reproduce the information**

#### Which of the following is the first integrated logic family?

- RTL
- DTL
- TTL
- MOS

**Answer - (1) RTL**

#### The time required for a pulse to change from 10 to 90 percent of its maximum value is defined as

- rise time
- decay time
- propagation tie
- operating speed

**Answer - (1) rise time**

#### The main advantages of CMOS as compared to TTL are

- lower power consumption and better noise margins
- lower poer consumption with low fanout
- higher speed operation with low power consumption
- higher power consumption with high fanout

**Answer - (1) lower power consumption and better noise margins**

#### Standard TTL has a multiple emitte input transistor and a output

- totem-pole
- chip
- bipolar
- loading-point

**Answer - (1) totem-pole**

#### Which of the following boolean algebra statements represent distributive law

- (A + B) + C = A + (B + C)
- A . (B + C) = (A . B) + (A . C)
- A . (B . C) = (A . B) . C
- None of these

**Answer - (2) A . (B + C) = (A . B) + (A . C)**

#### Which of the following boolean algebra statements represent commutative law

- (A + B) + C = A(B + C)
- A . (B + C) = (A . B) + (A . C)
- A + B = B + A
- A + A = A

**Answer - (3) A + B = B + A**

#### Which of the following logic expression is incorrect?

- 1 ⊕ 0 = 1
- 1 ⊕ 1 ⊕ 0 = 1
- 1 ⊕ 1 ⊕ 1 = 1
- 1 ⊕ 1 = 0

**Answer - (2) 1 ⊕ 1 ⊕ 0 = 1**

#### Let X and Y be the input and Z be the output of a AND gate. The value of Z is given by

- X + Y
- X . Y
- X . Y
- X . Y

**Answer - (2) X . Y**

What logic gate is represented by the circuit shown below

- NAND
- NOR
- AND
- EQUIVALENCE

**Answer - (3) AND**

#### The boolean expression A + BC equals

- (A + B) (A + C)
- (A + B) (A + C)
- (A + B) (A + C)
- none of these

**Answer - (2) (A + B) (A + C)**

#### The clock signals are used in sequential logic circuits to

- tell the time of the day
- tell how much time has elapsed since the system was turned on
- carry serial data singnals
- synchronize events in various parts of system

**Answer - (4) synchronize events in various parts of the system**

#### A positive AND gate is also a negative

- NAND gate
- NOR gate
- AND gate
- OR gate

**Answer - (2) NOR gate**

#### The term product-of-sum in boolean algebra means

- AND function of several OR functions
- OR function of several AND functions
- OR function of several OR functions
- AND function of several AND functions

**Answer - (1) AND functions of several OR functions**

#### An n stage ripple counter can count up to

- 2^n
- 2^n - 1
- n
- 2^(n-1)

**Answer - (2) 2^n - 1**

#### A 2 MHZ signal is applied to the input of a J-K flip-flop which is operating in the toggle mode. the frequency of the singal at the output will be

- 1 MHZ
- 2 MHZ
- 4 MHZ
- 8 MHZ

**Answer - (1) 1 MHZ**

#### Non-volatility is an important advantage of

- CCD's
- RAM
- PROM
- EPROM

**Answer - (3) PROM**

**Note** - More questions and answers related to the interview will be added from time to time.

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