Boolean Expression and Logic Circuit

Boolean Expression 

• Axioms of Boolean Algebra
• Basic Theorems
• Logical Addition (OR operation)
• Logical Multiplication (AND operation)
• Complementation 

Logic Gate

• an electronic circuit operates on one or more input signals to produce an output signal
• gates are digital signal (two-state) circuits 
• can be analyzed with Boolean Algebra
• OR gate    : circuit which performs OR operation
• AND gate  : circuit which performs AND operation

Electrical Switches

• closed / ON = 1
• open / OFF  = 0

Boolean Algebra

• basic rules for simplifying and combining logic gates 
• has either two values : true / false (1 or 0)
• two types of operator :  (i) Unary (NOT)     (ii)Binary (AND , OR)
• eg : Y = A . B @ Y = AB  @ Y = A+B  @ Y = A'

  Universal gates :

- gate that can have two or more inputs 

• NAND : its output is true if NOT all inputs are true
• NOR   : its output is true if no inputs are true 

Truth Table

• way to show the function of a logic gate
• shows the output states
• the symbols 0 (false) and 1 (true) are used in truth table
• example of truth table :