Adding Two Numbers Using Only NAND Gates
It's possible to build any kind of digital logic using a single type of logic gate: either NAND gates, or NOR gates. A NAND gate takes two input bits (A and B) and produces one output bit according to this simple rule: "0 if both inputs are 1, otherwise 1"
| A | B | A NAND B |
| 0 | 0 | 1 |
| 0 | 1 | 1 |
| 1 | 0 | 1 |
| 1 | 1 | 0 |
Any other logic function (AND, OR, NOT, XOR, etc.) can be constructed from combinations of NAND gates.
The following interactive component is an 8-bit ripple-carry adder built entirely from NAND gates. You can input two numbers (from 0-255), and watch the binary signals propagate through the circuit to produce the sum. (You can also click the individual input bits.)
You can view the source code on GitHub:
physics_sim/logic_gates/web_viz at main · ndbroadbent/physics_sim
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