The XR16L2552 (L2552) is a dual universal asynchronous receiver and transmitter (UART) with 5 volt tolerant inputs. The XR16L2552 is an improved version of the ST16C2552 UART with lower operating voltages and 5 volt tolerant inputs. The L2552 provides enhanced UART functions with 16 byte TX and RX FIFOs, automatic hardware (RTS/CTS) and software (Xon/Xoff) flow control, and a complete modem control interface. Onboard status registers provide the user with error indications and operational status. Indepedendent programmable baud rate generators are provided to select transmit and receive clock rates up to 3.125Mbps. An internal loop-back capability allows onboard diagnostics. The L2552 provides block mode data transfers (DMA) through FIFO controls. DMA transfer monitoring is provided through the signals TXRDY# and RXRDY#. An Alternate Function Register provides the user with the ability to write the control registers for both UARTs concurrently and selection of the Multi-Function output (Baudout#, OP2#, or RXRDY#). NOTE: