XOR Gate

The XOR Gate is a redstone circuit block added by the RedPower 2 mod. As the name suggests, it acts like a simple XOR gate for Redstone. The output is on when both input states are different. Another way to understand it is as follows: any time either input toggles, the output toggles. If you have two light switches in your house that work the same light, you understand an XOR gate.

The image on the right shows the 2 Inputs that are linked together. Similar gates are the OR Gate, the NOR Gate and the XNOR Gate.

Uses
When you have two levers in a room both controlling the piston that covers/reveals a glowstone block.

Logic Table
0's represent an inactive signal. 1's represent an active signal. Note that the outcome is equally to the Output of the NOR Gate.

Source
RedPower2 Wiki