The CDP6402 and CDP6402C are silicon gate CMOS Universal Asynchronous Receiver/Transmitter (UART) circuits for interfacing computers or microprocessors to asynchronous serial data channels. They are designed to provide the necessary formatting and control for interfacing between serial and parallel data channels. The receiver converts serial start, data, parity, and stop bits to parallel data verifying proper code transmission, parity and stop bits. The transmitter converts parallel data into serial form and automatically adds start parity and stop bits.