Example: Universal Gates from Simple ALU
Within this simple adder-only ALU, we can see that:
- The carry bit acts as a 2AND
- The sum bit acts as a 2XOR
- Further, wiring a 2XOR such that the two inputs going in are A and 1, the result will be \bar{A}
- This lets is do NAND, which is a universal gate.
- Further, wiring a 2XOR such that the two inputs going in are A and 1, the result will be \bar{A}