Other gates made with NAND

Source :: http://www.doctronics.co.uk/4011.htm

An important property of NAND gates is that they can be linked to perform the functions of other logic gates. In fact, any logic function can be implemented using only NAND gates:
If you have designed a system which needs a NAND gate, a NOT gate and an AND gate, you might think of using a separate integrated circuit for each logic function. This would leave you with a circuit in which there were three unused NAND gates, five unused NOT gates and three unused AND gates. It is a lot more efficient (and cheaper) to use NAND gates to implement the other functions. All three gates can be made with just one 4011 integrated circuit.

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