NAND, NOR, EX-OR and EX-NOR Gate





The concept of NAND gate, NOR gate, Universal gate, Boolean functions, logic circuits or networks are explained briefly. These concepts are very important to grasp theme and theory of advance computer courses offered by several universities.

NAND, NOR, EX-OR, EX-NOR gate:

 

(a) NAND Gate: The NAND gate has two or more inputs signals but only one output signals. All input signals must be high to get a low output.

Truth table:

A

B

(A.B)’

0

0

1

0

1

1

1

0

1

1

1

0

 

NAND Gate

NAND Gate


If the output of an AND gate is connected to the input of a NOT gate, the NAND circuit is formed.

 

(b) NOR Gate: The NOR gate has two or more input signals but only one output signals. All input must be low to get a high output. If the output of OR gate is connected to the input of a NOT gate, NOR gate is formed.

Truth Table:

A

B

(A+B)’

0

0

1

0

1

0

1

0

0

1

1

0

 

NOR Gate

NOR Gate


 

(c) X-OR (Exclusive-OR) Gate: It is also called Not-Equivalent (NEQ) gate. This gate gives a 1 if A is 1 or B is 1, but not if both are 1.

Truth Table:

A

B

XOR

0

0

0

0

1

1

1

0

1

1

1

0

X-OR Gate

X-OR Gate


 

(d) X-NOR or EQU (Equivalent) Gate: Logically equivalent to an XOR gate followed by an inverter. The truth table of X-NOR gate is the complement of an XOR truth table.  The output is the high when the inputs are same.

X-NOR Gate

X-NOR Gate

Truth table:

A

B

EQU

0

0

1

0

1

0

1

0

0

1

1

1



Related posts:

  1. Logic Gates The gate is an electronic circuit to receive more than...
  2. Why does Computer understand only binary? Q.  Why does Computer understand only binary? In computer system...
  3. Boolean Algebra Associated, Distributive, and Commutative Law are described below individually :...
  4. Binary and Decimal Number System Decimal Number System: The number of base or radix 10...
  5. Hexadecimal Number system and Their Conversion The number with base 16 is called hexadecimal number. It...