Page 38 - Digital Electronics by harish
P. 38
Realization of gates using NAND gates only
1) NOT gate using only NOR gates
Y =
= ( + ) ……. Because A + A = A
Hence, when we tie the two inputs of a NOR gate together we get a NOT gate.
2) OR gate using only NOR gates
Y = A + B
= + ……. Double complementation will give the same function
When the output of a NOR gate is connected to a NOT gate, we get an OR gate. One NOR
gate is used for + . Another NOR gate is used to implement the NOT function.
3) AND gate using only NOR gates
Y = A . B
= . ……. Double complementation will give the same function
= + ……. Using De-Morgan‟s second theorem, . = +
Two NOR gates are used for and . Another NOR gate is used for (+) and complement
functions.
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