Abstract: A UART compatible to a prior art UART provides a baud rate generator which can accept a higher frequency crystal oscillator to generate baud rates compatible with baud rates generated by the prior art UART without increasing the size of the frequency division circuit. In one embodiment, the UART of the present invention provides the capability for programmable flow control, including flow control for binary file transfers, using user-programmable multiple-character flow control words. In one embodiment, a sleep mode allows power conservation in the UART of the present invention.