Digital Flashcards
What is the meaning of the ‘AND’ logic gate? How many inputs can it have? What is the Boolean notation for the AND function? What is the logic symbol of an AND gate?
The output of an AND gate is true (1) iff (if, and only if) all of the inputs are true.
The gate can have any number of inputs.
The Boolean notation for the AND function is a dot (Y = A.B). However, the dot is often omitted (Y = AB).
The logic symbol for the AND gate is:
What is the meaning of the ‘OR’ logic gate? How many inputs can it have? What is the Boolean notation for the OR function? What is the logic symbol of an OR gate?
The output of an OR gate is true (1) iff (if, and only if) at least one of its inputs is true. It is also called the Inclusive OR gate.
The gate can have any number of inputs.
The Boolean notation for the OR function is ‘+’. For example the gate could be described by the expression C = A+B.
The logic symbol of an OR gate is:
What is the meaning of the ‘NOT’ logic gate? How many inputs can it have? What function does it fulfil? What is the Boolean notation for the NOT function? What is the logic symbol of a NOT gate?
The output of a NOT gate is true (1) iff (if, and only if) its single input is false.
This gate has the function of a logical inverter, since the output is the complement of the input. The gate is sometimes referred to as an invert gate or simply an inverter.
In Boolean notation, inversion is represented by putting a line (a bar) above the expression for the signal. An operation can be written as B = Ā, which reads as ‘B equals NOT A’ or as ‘B equals A bar’.
The logic symbol for a NOT gate is:
