A Universal Asynchronous Receiver-Transmitter (UART) converts parallel byte data into an asynchronous serial bitstream across a single conductor. To maintain synchronization without a shared clock distribution line, frames begin with an active-low Start bit, followed by 7 or 8 data bits (transmitted LSB first), an optional parity check bit, and one or two active-high Stop bits. Receiver clock circuitry samples transmission lines at sixteen times the baud rate to identify the stable center of each bit period.