2-input NAND gate using 2:1 mux

2-input NAND gate using 2:1 mux: Figure 3 below shows the truth table of a 2-input NAND gate. If we observe carefully, OUT equals '1' when A is '0'. Similarly, when A is '1', OUT is B'. So, if we connect SEL pin of mux to A, D0 pin of mux to '1' and D1 to B', then it will act as a NAND gate.

In a 2-input NAND gate, output is '0' when both inputs are '1', otherwise output is '1'
Figure 3: Truth table of 2-input NAND gate

Figure 4 below shows the implementation of a 2-input NAND gate using 2:1 mux.


A NAND gate can be implemented using a 2-input multiplexer, if we connect the select pin of the multiplexer to A, D0 to VDD and D1 to B' inputs. NAND gate using mux, NAND gate using 2x1 mux
Figure 4: Implementation of 2-input NAND gate using 2:1 mux

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2-input OR gate using 2:1 mux

2-input OR gate using 2x1 mux: Figure 5 below shows the truth table for a 2-input OR gate. If we observe carefully, OUT equals B when A is '0'. Similarly, OUT is '1' (or A), when A is '1'. So, we can make a 2:1 mux act like a 2-input OR gate, if we connect D0 pin to B and D1 pin to A, with select connected to A.

In a 2-input OR gate, output is '1' when either or both of the inputs are '1'. Otherwise, output is '0'.
Figure 5: Truth table of 2-input OR gate

Figure 6 below shows the implementation of 2-input OR gate using a 2:1 multilpexer:


A 2-inputs multiplexer can be converted to an OR gate, if we connect the select pin of mux to A-input, D0 to B-input and D1 to VDD. OR gate using mux, OR gate using 2x1 mux
Figure 6: Implementation of 2-input OR gate using 2:1 mux

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