1. Truth Tables and Logic Gates

2. What are Logic Gates? Logic gates are components used in making logic circuits. Each gate has one or more inputs and produces a single output which depends upon the input(s) LOGIC GATE Input (1 or more) 1 Output as an electrical pulse

3. What do Logic Gates do? Provide control of information flow Perform arithmetic and logic functions Help to store information and provide timing circuiting

4. The NOT Gate When the switch is on …. the LED is off When the switch is off …. the LED is on The NOT gate has only one input and one output The output of the NOT gate is the inverse of its input. A not gate is also known as an inverter

5. The NOT Gate – Truth Table 01 10 OUTPUTINPUT The Boolean expression is written as: P = NOT A or P = Ā

6. The OR Gate The output of an OR gate is TRUE if any input is TRUE, otherwise the output is FALSE An OR gate have two or more inputs and one output

7. The Or Gate – Truth Table The Boolean expression is written as: P = A OR B or P = A + B 111 101 110 000 OUTPUTINPUT

8. The AND Gate The output of an AND gate is similar to the output given by a series electrical circuit The electric circuit shown below has 2 inputs (switches) A and B and 1 output P

9. Truth Table of AND Gate The Boolean expression is written as: P = A AND B or P = A. B 111 001 010 000 OUTPUTINPUT