Editing Comparison of synchronous and asynchronous signalling (section)

===Synchronous transmission===
In synchronous communications, the stream of data to be transferred is encoded as fluctuating voltage levels in one wire (the 'DATA'), and a periodic pulse of voltage on a separate wire (called the "CLOCK" or "STROBE") which tells the receiver "the current DATA bit is 'valid' at this moment in time".

Practically all [[parallel communications]] protocols use synchronous transmission. For example, in a computer, address information is transmitted synchronously—the address bits over the [[address bus]], and the read or write strobes of the [[control bus]].

[[Image:EmbeddedSynchronousSignalling.png|thumb|350px|Single-wire synchronous signalling]]

A logical one is indicated when there are two transitions in the same time frame as a zero. In the Manchester coding a transition from low to high indicates a one and a transition from high to low indicates a zero. When there are successive ones or zeros, an opposite transition is required on the edge of the time frame to prepare for the next transition and signal.