Logic Gates are electronic circuits which perform Boolean functions. Several symbols are used to define logic gates. Logic Gates form the basis of all logic circuits. Inputs to outputs from electronic logic gates are in the form of voltages; a high voltage represents a high state (1) and a low voltage represents a low state (0). These low and high states are what an electronic piece of equipment can read in a binary format.
Half Adders - A Half-Adder uses two inputs, an XOR gate and an AND gate, and is used two add two digits, and carry over that number two the next adder.
Full Adders - A Full-Adder adds three bits, and is comprised of three inputs, two XOR gates, two AND gates and an OR gate.
A processor uses Half Adders and Full Adders to perform simple calculations
| AND Gate | Both inputs must be true (1) for the output to be true(1) | Looks like a D with Two Inputs and One Output Boolean: A.B |
| ||||||||||||||||||
| OR Gate | Used to express that either input or both being true (1) will give an output that is true (1) | A curved back to it with a slightly pointed front. Two Inputs, One Output Boolean: A+B |
| ||||||||||||||||||
| NOT Gate | Only one input. The input must be false (0) for the output to be true (1) These logic gates will only have one output. | A Triangle with One Input and One Output
Boolean: A |
| ||||||||||||||||||
| XOR Gate (Extended OR) | Used to express that either output but not both being true will give an output that is true. |
| |||||||||||||||||||
| NAND Gate (Not AND) | As long as both of the inputs are false (0) then the outputs will be false (0) |
| |||||||||||||||||||
| NOR Gate (Not OR) | Only if both inputs are false (0) will the output be true (1) |
| |||||||||||||||||||
| XNOR Gate (Extended NOR) | If neither or both of the inputs are true (1), then the output will be true (1) Therefore, if one input is true (1) and the other is false (0) then the output will be false (0) |
| |||||||||||||||||||
