The XR68C92/192 is a Dual Universal Asynchronous Receiver and Transmitter with 8 (XR68C92) or 16 (XR68C192) bytes of transmit and receive FIFOs. The XR68C92/192 is pin-to-pin and functionally compatible to the XR68C681 and Philips SCC68681 UART with additional features. The operating speed of the receiver and transmitter can be selected independently from a table of twenty four fixed baud rates, a 16X clock derived from a programmable counter/ timer, or an external 1X or 16X clock. The baud rate generator and counter/timer can operate directly from a crystal or from external clock input. The XR68C92/192 provides a power down mode in which the oscillator is stopped but the register contents are retained. The XR68C92/192 is fabricated in an advanced CMOS process to achieve low power and high speed requirements.