Circuitry for locating the boundaries between bytes in a data stream is only selectively enabled to find a possible new byte alignment by a control signal. After the byte alignment circuitry has found a byte alignment, it outputs byte-aligned data and a first status signal indicating the presence of such data. If the byte alignment circuitry subsequently detects information that suggests a possible need for a new or changed byte alignment, it outputs a second status signal to that effect. However, the byte alignment circuitry does not actually attempt to change its byte alignment until enabled to do so by the control signal. Programmable logic circuitry or other utilization circuitry is typically provided to receive the outputs of the byte alignment circuitry and to selectively provide the control signal.