Experiment 3 - The OR Gate

A further possibility is the OR gate. It combines two inputs with the OR logic. The result Q is equal to 1 if the inputs A OR B, OR both are equal to 1.

Also for this logical combination, there is a corresponding logic in language use: "The bicycle is locked when it is locked by a U-lock or a chain lock" To you it is intuitively obvious that the bicycle is also locked when it is locked with both, a U-lock and a chain lock.

A B Q 0 0 0 0 1 1 1 0 1 1 1 1 Truth Table of the OR-logic.

OR-symbol in circuit diagrams.

The easiest way to realize a circuit with OR logic is by replacing the IC from Experiment 2 by the C-MOS IC 4071.

A OR circuit. (Enlarge)

Basic Gates The three gates (NOT, AND und OR), that you've come to know until now, are referred to as basic gates. But what are basic gates? There is a simple definition: All other gates can be represented as a combination of basic gates. But more about that later, because there are several ways to determine basic gates.

Perhaps you are wondering about the OR logic. In language OR is often used in another logical context...