(31337_13079267765950, `The truth tables of the four fundamental gates are symmetrical. You can convert between them by [color=#6e9759][b]inverting the input[/b][/color] (vertical arrows) or [color=#595f99][b]inverting the output[/b][/color] (horizontal arrows) as indicated by the graphic below.

[center][image="de morgan.png"][/center]

Notes
1. You can get from any basic gate to any other, at most you have to NOT both inputs and output.
2. You can go between OR/NOR by inverting output, the same with AND/NAND. In fact NOR means NOT OR and NAND means NOT AND. Notice the component shape of OR/NOR are identical except for the little dot at the tip which means NOT. The same is true for AND/NAND.
3. Negating the output flips all the bits in the last row of the truth table. Negating the inputs mirrors the last row of the truth table around the center.`)