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A gated SR latch circuit diagram constructed from AND gates (on left) and NOR gates (on right) A gated SR latch can be made by adding a second level of NAND gates to an inverted SR latch. The extra NAND gates further invert the inputs so a SR latch becomes a gated SR latch (a SR latch would transform into a gated SR latch with inverted enable).
The NOR gate is a digital logic gate that implements logical NOR - it behaves according to the truth table to the right. A HIGH output (1) results if both the inputs to the gate are LOW (0); if one or both input is HIGH (1), a LOW output (0) results. NOR is the result of the negation of the OR operator.
If both inputs are 1, then the pull-down network changes the latch's state, making the C-element output a 1. Otherwise, the input of the latch is not connected to either or ground, and so the weak inverter dominates and the latch outputs its previous state. There are also versions of semistatic C-element built on devices with negative ...
A single NOR gate. A NOR gate or a NOT OR gate is a logic gate which gives a positive output only when both inputs are negative.. Like NAND gates, NOR gates are so-called "universal gates" that can be combined to form any other kind of logic gate.
A CMOS transistor NAND element. V dd denotes positive voltage.. In CMOS logic, if both of the A and B inputs are high, then both the NMOS transistors (bottom half of the diagram) will conduct, neither of the PMOS transistors (top half) will conduct, and a conductive path will be established between the output and Vss (ground), bringing the output low.
Figure 2. The Set–Reset NOR latch example. A simple example of metastability can be found in an SR NOR latch, when both Set and Reset inputs are true (R=1 and S=1) and then both transition to false (R=0 and S=0) at about the same time.
First introduce the SR latch. Next introduce the clocked SR latch (i.e., SR latch with AND gates in front and a "clock" input). Next introduce the edge-triggered SR flip flop. Next introduce the edge-triggered JK flip flop. Add combinational logic to describe D and T flip flops.
The flip-flop has many different implementations, its storage element is usually a latch consisting of a NAND gate loop or a NOR gate loop with additional gates used to implement clocking. Its value is always available for reading as an output.