“NOR-Gate” in Minecraft

Place two blocks next to eachother (distance: one block). Install two redstone-lanes (both connected to a lever) which end in these blocks. Connect these two input-lanes.
nicht_oder_gatter-1

Put two redstone-torches at the other side of the blocks.
nicht_oder_gatter-2

Create the output-lane by connecting the two redstone torches using redstone-lanes.
nicht_oder_gatter-3

Explanation:

  • If both the inputs to the gate are negative, the output becomes positive.
  • If one or both input is powered, the output becomes negative.