Basic Concept Digital

Digital Electronics And Microprocessor

Boolean Algebra And Logic Gates Introduction • Definition • Need of Digital Systems. • Developments

Analog Signal: A continuous signal that can have any value in a given range. Analog Systems: An electronic System that consists of analog Circuits and devices.

Digital Signal: A signal with only two discrete values. These are usually represented by 0 & 1 or(Low &High). Digital Systems: An electronic system that consists of digital circuits and

Digital Signals Positive Logic

Negative Logic

Basic Digital Circuits: • Logic Gates • Logic Operations • Truth Table

AND GATE A B

Y = AB

Truth Table Inputs A 0 0 1 1

B 0 1 0 1

Output Y=AB 0 0 0 1

OR GATE

N

Y=A+B+ •••• N

Truth Table Inputs A 0 0 1 1

B 0 1 0 1

Output Y=A+B 0 1 1 1

NOT GATE

Input

Output

A 0

Y=A 1

1

0

NAND GATE

Y = AB • • • N

NAND GATE Truth Table Inputs A 0 0 1 1

B 0 1 0 1

Output Y=AB 1 1 1 0

Realization of Basic Logic Operations Using NAND Gate

NOR Gate

Y = A + B + ••• + N

Symbol

Truth Table Inputs A 0 0 1 1

B 0 1 0 1

Output Y=A+B 1 0 0 0

Realization Of Basic Logic Operation using NOR Gate

EXCLUSIVE – OR GATE (XOR)

Y = A` B + A B` Y=A⊕ B

EXCLUSIVE – OR GATE Truth Table Inputs A 0 0 1 1

B 0 1 0 1

Output Y=A⊕B 0 1 1 0

EXCLUSIVE – NOR GATE

Y = A B + A`B` Y = (A ⊕ B)`

EXCLUSIVE – NOR GATE Truth Table Inputs A 0 0 1 1

B 0 1 0 1

Output Y=(A⊕B)` 1 0 0 1