The TL16C2552 is a dual universal asynchronous receiver and transmitter (UART). It incorporates the functionality of two TL16C550D UARTs, each UART having its own register set and FIFOs. The two UARTs share only the data bus interface and clock source, otherwise they operate independently. Another name for the uart function is Asynchronous Communications Element (ACE), and these terms will be used interchangeably. The bulk of this document will describe the behavior of each ACE, with the understanding that two such devices are incorporated into the TL16C2552.