asynchronous bus
In computer architecture, a bus is a subsystem that transfers data between components inside a computer, or between computers.
Early computer buses were literally parallel electrical wires with multiple connections, but the term is now used for any physical arrangement that provides the same logical functionality as a parallel electrical bus. Modern computer buses can use both parallel and bit serial connections, and can be wired in either a multidrop (electrical parallel) or daisy chain topology, or connected by switched hubs, as in the case of USB.