The OX16PCI958 contains eight UARTs (Universal Asynchronous Receiver-Transmitters) and a host interface suitable for direct connection to a PCI bus. Once installed and configured by the host OS, it provides an eight-byte programming interface to each UART. The UARTs are fully software-compatible with 16C550 devices. The device can be configured to fit the requirements of RS232 or RS422 applications. The UARTs convert between RS232-format serial data on separate transmit and receive lines, and byte-wide I/O writes and reads on the host interface. Malformed incoming serial data is flagged along with the data in the receive FIFO. The state of the UART can be found at any time by reading status registers, and modem control (handshaking output) lines can be individually controlled. Although polled-mode operation is possible, the UART will usually be operated on a host-interrupt basis. The interrupt system is designed to allow efficient handling of