The MC74AC646/74ACT646 consist of registered bus transceiver circuits, with outputs, Dtype flipflops and control circuitry providing multiplexed transmission of data directly from the input bus or from the internal storage registers. Data on the A or B bus will be loaded into the respective registers on the LOWtoHIGH transition of the appropriate clock pin (CAB or CBA). The four fundamental data handling functions available are illustrated Figures 1 to 4.