或门
The SR AND-OR latch is easier to understand, because both gates can be explained in isolation. When neither S or R is set, then both the OR gate and the AND gate are in "hold mode", i.e., their output is the input from the feedback loop. When input S = 1, then the output of the OR gate becomes 1, regardless of the other input from the feedback loop ("set mode"). When input R = 1 then the output of the AND gate becomes 0, regardless of the other input from the feedback loop ("reset mode"). And since the output Q is directly connected to the output of the AND gate, R has priority over S. Latches drawn as cross-coupled gates may look less intuitive, as the behaviour of one gate appears to be intertwined with the other gate.