Spring 2000 Computer Science 3410 - Tutorials Derived Gates         This is the NAND gate. It implements an inverted AND gate. The circle at the output of the gate denotes the inversion. The bar above both inputs means that the inversion is applied to the AND function and not to each input separately.         This is the NOR gate. Similar to the NAND gate, this gate implements an inverted NOR gate. The circle on the output denoted the inversion.         This is the XOR, or the Exclusive-OR, gate. It is a variation of the standard OR gate and the operator used is a plus sign (+) with a circle around it.