The NAND gate is the same function as an AND gate with the output inverted. The logic symbol for a NAND gate is the same as an AND gate except it has a small bubble on the output to indicate that the output is inverted.
The NAND operation is shown with a dot between the variables and an overbar covering them. Thus, the NAND operation is written as X = 
(Alternatively, X =
). The truth table for the NAND gate shows the output to be just the inverse of the output of an AND gate. The only time the output is low is when all the inputs are high.) The output of a NAND gate can be shown with a timing diagram in the same manner that the output of the AND and OR gate were developed.
Example Waveform:
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Date last modified: January 17, 2013.
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