Saturday, July 20, 2013

Boolean Operations

Boolean operations are used to develop logical circuits. This will be a brief overview of these functions. We will establish a truth table, where 1 represents an on signal, 0 represents an off signal. Q is just the result of applying our function using the Boolean operation specified

Q = A.B

AND Gate
The AND gate is an important function, we can think of this as multiplication as if we multiple the two signal together here we arrive at the following truth table for an AND gate.

A B Q
0 0 0
0 1 0
1 0 0
1 1 1




Q = Q̅ = A.B

Function NAND
This is the NAND gate or the not AND gate. This simply reverses all the outputs of our AND gate.

A B Q
0 0 1
0 1 1
1 0 1
0 0 0



Q = A + B

Function OR
The OR gate is similar to addition. However, its a version of addition that does not know how to carry over, as we can see by the last part of the truth table, but otherwise functions similarly.

A B Q
0 0 0
0 1 1
1 0 1
1 1 1




Q = Q̅ = A + B

Function NOR
Again like the NAND gate, the NOR gate simply reverses the signal of the OR gate.

A B Q
0 0 1
0 1 0
1 0 0
1 1 0




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