LOGIC GATES : BASIC DIGITAL
BASIC DIGITAL: LOGIC GATES AND DETAILS
Digital is a part of Electronics. Basically electronics has
two different types, one is Analog and the other one is Digital. Analog
circuits are mainly deals with the analogues signal, means it mainly consists
mechanical circuits. On the other hand Digital circuits are deals with the
digital signals, means it consists of digital display.
 |
| Analog Clock |
 |
| Digital Clock |
To know brief about digital circuits’ at-first one should
know about Logic Gates.
Logic gates are the basic building blocks of any Digital
Circuit. These are called ‘Gates’ as we can give inputs and the gate gives us
an output and these gates work logically.
Basically there are 7 logic gates; AND, OR, NOT, NAND, NOR, XOR
& XNOR. The symbol of each gate, their expressions and the Truth tables are
given below :
AND Gate:
Symbol:
Inputs: A & B Output: Y
Expression: Y = A.B
Truth Table:
A
|
B
|
Y
|
0
|
0
|
0
|
0
|
1
|
0
|
1
|
0
|
0
|
1
|
1
|
1
|
OR Gate:
Symbol:
Inputs: A & B Output: Y
Expression: Y = A+B
Truth Table:
A
|
B
|
Y
|
0
|
0
|
0
|
0
|
1
|
1
|
1
|
0
|
1
|
1
|
1
|
1
|
NOT Gate:
Symbol:
Inputs: A & B Output: Y
Expression: Y = A
Truth Table:
A
|
Y
|
0
|
1
|
1
|
0
|
NAND Gate: AND+NOT
Symbol:
Inputs: A & B Output: Z
Expression: Z = A.B
Truth Table:
A
|
B
|
Z
|
0
|
0
|
1
|
0
|
1
|
1
|
1
|
0
|
1
|
1
|
1
|
0
|
NOR Gate: OR+NOT
Symbol:
Inputs: A & B Output: Z
Expression: Z = A+B
Truth Table:
A
|
B
|
Z
|
0
|
0
|
1
|
0
|
1
|
0
|
1
|
0
|
0
|
1
|
1
|
0
|
XOR Gate:
Symbol:
Inputs: A & B Output: Y
Expression: Y = A B + AB
Truth Table:
A
|
B
|
Y
|
0
|
0
|
0
|
0
|
1
|
1
|
1
|
0
|
1
|
1
|
1
|
0
|
XNOR Gate: XOR+NOT
Symbol:
Inputs: A & B Output: Y
Expression: Y = AB + A . B
Truth Table:
A
|
B
|
Y
|
0
|
0
|
1
|
0
|
1
|
0
|
1
|
0
|
0
|
1
|
1
|
1
|
A Final Result of all Truth Tables of the Gates :
A
|
B
|
AND
|
OR
|
NAND
|
NOR
|
XOR
|
XNOR
|
0
|
0
|
0
|
0
|
1
|
1
|
0
|
1
|
0
|
1
|
0
|
1
|
1
|
0
|
1
|
0
|
1
|
0
|
0
|
1
|
1
|
0
|
1
|
0
|
1
|
1
|
1
|
1
|
0
|
0
|
0
|
1
|
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