Source : Free On-Line Dictionary of Computing

circular buffer
     
         An area of {memory} used to store a continuous
        stream of data by starting again at the beginning of the
        buffer after reaching the end.  A circular buffer is usually
        written by one process and read by another.  Separate read and
        write {pointers} are maintained.  These are not allowed to
        pass each other otherwise either unread data would be
        overwritten or invalid data would be read.
     
        A circuit may implement a {hardware circular buffer}.
     
        (2000-06-17)