A bubble on the input or output of a logic gate indicates __________ logic.

A bubble on the input or output of a logic gate signifies the presence of inverted logic, specifically indicating that the output is the negation of the input. In digital logic, this is often represented using a NOT operation, where the bubble serves as a symbol to show that the signal is inverted.

When used with a gate, such as a NOT gate, the bubble signifies that if the input is high (1), the output will be low (0), and vice versa. Thus, the presence of a bubble directly correlates with the NOT function, confirming that the logic is indeed inverted. This concept is critical for understanding how combinational circuits function and how different logic levels combine to produce desired outputs.

In contrast, other gates like AND and OR do not inherently feature bubbles, as their basic operations do not involve inversion. The NAND gate, while a combination of AND followed by an inversion, requires a more complex configuration indicating both operations rather than a simple bubble indicating negation. Therefore, recognizing the bubble in the context of basic gates points directly to NOT logic as the correct interpretation.