A device that funnels two peripheral devices into the same port. For example, it is commonly used to connect a mouse and keyboard to the same port. Passive dual input adapters may work, but active devices that contain built-in intelligence monitor user actions and channel the signals more effectively.
The Y-Mouse
The Y-mouse adapter from P.I. Engineering is a microprocesser-controlled device for connecting a keyboard and mouse to the same computer port. (Image courtesy of P.I. Engineering,Inc.)