Logic Gates
Controlling electricity gives us the ability to make yes and no decisions or true and false. By combining two signals, we can give a single true or false answer, depending on the logic. The flow of electricity is controlled using gates (no, not named after Bill Gates - like a gate).
The simplest gate, this item inverts or reverses the signal.
Input (A) | Output (Q) |
0 | 1 |
1 | 0 |
Only outputs true if both inputs are true.
A | B | Output (Q) |
0 | 0 | 0 |
0 | 1 | 0 |
1 | 0 | 0 |
1 | 1 | 1 |
Any gate with a dot is an inverted gate.
This is the NOT AND gate:
A | B | Output (Q) |
0 | 0 | 1 |
0 | 1 | 1 |
1 | 0 | 1 |
1 | 1 | 0 |
One or the other or both!
A | B | Output (Q) |
0 | 0 | 0 |
0 | 1 | 1 |
1 | 0 | 1 |
1 | 1 | 1 |
Very simply NOT OR.
A | B | Output (Q) |
0 | 0 | 1 |
0 | 1 | 0 |
1 | 0 | 0 |
1 | 1 | 0 |
Exclusive OR meaning only one is true, not both.
A | B | Output (Q) |
0 | 0 | 0 |
0 | 1 | 1 |
1 | 0 | 1 |
1 | 1 | 0 |
Exclusively NOT OR. If both inputs are the same, output true.
A | B | Output (Q) |
0 | 0 | 1 |
0 | 1 | 0 |
1 | 0 | 0 |
1 | 1 | 1 |
The two "universal" gates are NOR and NAND - it is said that you can create all the other logic gates with a combination of just these two.
There are tons of videos available about logic gates. If I had to pick a favourite, my current is this one, although she talks incredibly fast and you might need to slow it down or rewind.
