The term "universal gate" usually refers to logic gates that can be used to create any other type of logic gate or any Boolean function. In the context of universal gates, we often talk about NAND and NOR gates, as they are known for this property.
However, the term "9" is not commonly associated with universal gates in standard logic design terminology. Itβs possible that "9" might refer to something specific in a certain context or system that isn't widely recognized in general logic design theory.
If you have a particular context or example where "9" is mentioned as a universal gate, could you provide more details? This would help in giving a more precise explanation.