I find that EE references are boring as a rule--you can't just curl up by the fire and read "Electrical Circuits, 6th Edition" and expect to get anything useful out of it. You wouldn't sit down and read a cookbook or a dictionary--rather, you familiarize yourself with it, then read the parts...
Sounds like a multiplexer
A 2:1 multiplexer will have 2 inputs, a select line, and a single output. The output will be the selected input: that is, if there is a logic "0" (ground) on the select line, the output will be input 0, and if there is a logic "1" on the select line the output will be...