The CT1775 Universal MACAIR/1553 Dumb Remote Terminal Unit (RTU) consists of a transceiver, and encoder/decoder, control logic, dual rank I/O registers and internal clock oscillator packaged in a 1.6" x 1.9" hermetic hybrid. It provides all the functions required to interface between a MACAIR (sinusodial) or MIL-STD-1553 (Trapezoidal) serial MUX data bus and a subsystem parallel 3-state data highway. Utilizing several ASIC ICs, the CT1775 provides sufficient handshaking, control and data lines to permit versatile operation as a remote terminal, a bus controller or a bus monitor, in either single or dual redundant data bus configurations. As a transmitter, the CT1775 accepts 8 bit or 16 bit parallel date from the subsystem, and outputs serial Manchester II coded Command, Status or Data words, under subsystem control. As a receiver, it accepts serial MIL-STD-1553 or MACAIR transmissions and transfers all Command, Status and Data words to the 8 bit or 16 bit data highway, under subsystem control. The CT1775 also provides flags to the subsystem when Broadcast, Mode Code, and Own Address (with parity) commands are decoded.