The CD74FCT653 is an octal bus transceiver and register with open-collector and 3-state outputs. It consists of D-type flip-flops and control circuitry arranged for multiplexed transmission of data directly from the data bus or from the internal storage registers. Output-enable (OEAB and OEBA) inputs control the transceiver functions. Select-control (SAB and SBA) inputs select real-time-data or stored-data transfer. The select-control circuitry eliminates the typical decoding glitch that occurs in a multiplexer during the transition between stored data and real-time data. A low input level selects real-time data, and a high input level selects stored data. The device uses a small-geometry BiCMOS technology. The output state is a combination of bipolar and CMOS transistors that limits the output high level to two diode drops below VCC. This resultant lowering of output swing (0 V to 3.7 V) reduces power-bus ringing [a source of electromagnetic interference (EMI)] and minimizes VCC bounce and ground bounce and their effects during simultaneous output switching. The output configuration also enhances switching speed and is capable of sinking 64 mA. The CD74FCT653 is an inverting type, having open drains on the A output and 3-state outputs on the B side. Data on the A or B data bus, or both, can be stored in the internal D-type flip-flops by low-to-high transitions at the appropriate clock (CLKAB or CLKBA) terminals, regardless of the state of the select- or output-control terminals. When SAB and SBA are in the real-time transfer mode, it is possible to store data without using the internal D-type flip-flops by simultaneously enabling OEAB and OEBA. In this configuration, each output reinforces its input. When all other data sources to the two sets of bus lines are at high impedance, each set of bus lines remains at its last state. The CD74FCT653 is characterized for operation from 0C to 70C.