Minecraft wiki entry for Memory, associated text: Designs A and B are the most fundamental RS-NOR latches. In both cases, their inputs and outputs are "duplex"—the latch state can be read (Q) or set (S) on one side of the circuit, while on the other side, the latch can be reset (R), or the inverse output read (Q̅). If separate lines for input and output are needed, opposite ends of B can be used, or A can be elaborated into A' with separate locations for all four lines.