There are many situations in digital circuit design where the passage of a logic signal needs to be either enabled or inhibited depending upon certain other control inputs. INHIBIT here means that the gate produces a certain fixed logic level at the output irrespective of changes in the input logic level. As an illustration, if one of the inputs of a four-input NOR gate is permanently tied to logic ‘1’ level, then the output will always be at logic ‘0’ level irrespective of the logic status of other inputs. This gate will behave as a NOR gate only when this control input is at logic ‘0’ level. This is an example of the INHIBIT function. The INHIBIT function is available in integrated circuit form for an AND gate, which is basically an AND gate with one of its inputs negated by an inverter. The negated input acts to inhibit the gate. In other words, the gate will behave like an AND gate only when the negated input is driven to a logic ‘0’.