1. Simple One and Two Input Logic Gates Truth Tables and Function Tables Based Upon 0 – 5 V

2. Assumptions Truth Tables – True = logical “1” – False = logical “0” Function Tables – Ideal gate Output is 0V, which is equivalent to a logical “0” Output is 5V, which is equivalent to a logical “1” for TTL.

3. Single Input Gates: Buffer Symbol Truth Table Function Table AZ 00 11 VAVA VoVo 0V 5V

4. Applications Reshape signal to increase voltage of a logical ‘1’/lower the voltage of a logical ‘0’. – Digital signals degrade as the signal passes through components (e.g., resistive losses in wires), addition of noise from electromagnetic interference (EMI), etc. Source or sink current beyond the specifications of the other gates. – Acts as a voltage follower (an op amp circuit). Used to compensate for propagation delay times.

5. Single Input Gates: Inverter Symbol Truth Table Function Table AZ 01 10 VAVA VoVo 0V5V 0V

6. Two Input Gates: AND Symbol Truth Table Function Table ABZ 000 010 100 111 VAVA VBVB VoVo 0V 5V0V 5V0V 5V

7. Two Input Gates: OR Symbol Truth Table Function Table ABZ 000 011 101 111 VAVA VBVB VoVo 0V 5V 0V5V

8. Two Input Gates: NAND Symbol Truth Table Function Table ABZ 001 011 101 110 VAVA VBVB VoVo 0V 5V 0V5V 0V5V 0V

9. Symbol Truth Table Function Table ABZ 001 010 100 110 VAVA VBVB VoVo 0V 5V 0V5V0V 5V0V 5V 0V Two Input Gates: NOR

10. Two Input Gates: XOR Truth Table Function Table ABZ 000 011 101 110 VAVA VBVB VoVo 0V 5V 0V5V 0V Symbol

11. 2 bit Adder 0 + 0 = 00 0 + 1 = 01 1 + 0 = 01 1 + 1 = 10 ABLSB 000 011 101 110 ABCarry 000 010 100 111

12. 2 bit Adders A half adder is an Exclusive OR gate. – The output of the XOR gate is the least significant bit (LSB) of the addition of 2 1-bit numbers. A adder with carry is an XOR gate and an AND gate. – The output of the XOR gate is the LSB. – The output of the AND gate is the Carry.