Non-Invert Cells are part of RedPower2 and are used in RedPower Logic circuits. They allow for input to be supplied to both the upper and lower wires. When the lower wire gets powered, the upper one gets powered too, thus acting like an OR Gate. However, when the upper wire is powered, the lower wire will not be powered, thus acting like a diode or Repeater. Thus, this can be used as a diode to control the output for several circuits, such as the RS Latch and the Counter, in which the inputs are also outputs. If a diode is not used, the signal will travel all the way back through the input wire, possibly triggering other circuits connected to that wire.