NAND Gate Bistable

A NAND gate bistable is a flip-flop circuit consisting of a pair of NAND gates. It is possible to make flip-flop circuits using transistors; however, logic gates can also be used for making them. Two stage flip-flops have two stable states of logic 1 and logic 0, and therefore they are bistables.

As you can see from the logic symbol, this type of bistable has two outputs Q, and /Q. They are both opposing so when Q=1, /Q=0, and when Q=0, /Q=1.

When you press the SET switch, the bistable output Q=1, and /Q=0. The outputs remain locked like this even if you press the SET switch many more times. When you press the RESET switch, the output Q=0, and /Q=1, and it remains locked in this state even if you press the RESET switch many more times. As you can see, this simple flip-flop maintains one state or the other, and behaves as a memory.

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