DIGITAL ELECTRONICS

Question 1

3 important characteristics of any number system

Answer 1

1) base or radix is equal to number of digits in the system
2)largest value of digit is one less than base or radix
3)each digit is multiplied by base or radix raised to an appropriate power depending upon the digital position to get its place value

Question 2

Radix of binary number system

Answer 2

2

Question 3

Radix of octal number system

Answer 3

8

Question 4

Radix of hexadecimal number system

Answer 4

16

Question 5

Binary addition
0+0
0+1
1+0
1+1

Answer 5

0
1
1
10

Question 6

Binary subtraction
0-0
1-0
1-1
10-1

Answer 6

0
1
0
1

Question 7

Binary multiplication
00
01
10
11

Answer 7

0
0
0
1

Question 8

Binary division
0/1
1/0

Answer 8

0
1

Question 9

First complement

Answer 9

changing each 0 to a 1 and each 1 to a 0

Question 10

second complement

Answer 10

it is obtained by adding 1 to the first complement of the number

Question 11

Signed binary numbers
0
1

Answer 11

0 : positive charge
1: negative charge

Question 12

advantage of signed binary numbers:

Answer 12

simplicity

Question 13

disadvantage of signed binary numbers

Answer 13

they have to be converted to unsigned binary form before arithmetic operations can be performed

Question 14

Floating point number

Answer 14

Number is written as a fraction multiplied by some power of base or radix

Question 15

Mantissa in floating point number

Answer 15

fractional part of floating point number

Question 16

Exponent in floating point number

Answer 16

Power of base or radix multiplying the fraction

Question 17

Types of Gates

Answer 17

AND
OR
NOT
NOR
NAND
EX. OR
EX. NOR

Question 18

Commutative law

Answer 18

A+B = B+A
A.B = B.A

Question 19

Associative law

Answer 19

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

Question 20

Distributive law

Answer 20

A.(B+C) = AB +AC

Question 21

Absorption laws

Answer 21

A +AB =A
A.(A+B) = A
A + (A’B) = A+B
A. (A’+B) = A.B

Question 22

Operations

Answer 22

A+0 = A
A + A =A
A+1 = 1
A + A’ = 1

Question 23

AND operations

Answer 23

A.1 = A
A.A =A
A.0 = 0
A.A’ = 1

Question 24

Double inversion

Answer 24

(A’)’ = A

Question 25

De morgan theorem

Answer 25

(AB)’ = A’ + B’
(A+B)’ = A’ . B’

Question 26

Universal gates

Answer 26

A gate which can implement any boolean function without need to use any other gate type
ex : NAND and NOR

Question 27

Half adder

Answer 27

Arithmetic circuit block that can be used to add 2 bits

Question 28

half adder output

Answer 28

Sum, S = A.B’ + A’B
Carry, C = A.B

Question 29

Full adder

Answer 29

Arithmetic circuit block that can be used to add 3 bits to produce a sum and carry output

Question 30

Full adder output

Answer 30

Carry , C* = C(A’B + AB’) + AB
Sum , S =C’ (A’B + AB’) + C (AB + A’B’)

Question 31

Flip Flop

Answer 31

circuits that have 2 stable states that can store state information

Question 32

flip flop AKA

Answer 32

bistable multivibrator
latch
toggle

Question 33

Applications of Flip flop

Answer 33

Counters
Frequency dividers
shift registers
storage register

Question 34

R-S flip flop

Answer 34

A pair of cross coupled 2 unit NAND gates is the simplest way to make a set-reset RS flip flop

Question 35

JK Flip flop

Answer 35

it is an ideal memory element for counting circuits. It can be realized from a RS flip-flop by augmenting 2 AND gates