The TL16C451 and TL16C452 provide single- and dual-channel (respectively) serial interfaces along with a single Centronix-type parallel-port interface. The serial interfaces provide a serial-to-parallel conversion for data received from a peripheral device or modem and a parallel-to-serial conversion for data transmitted by a CPU. The parallel interface provides a bidirectional parallel data port that fully conforms to the requirements for a Centronix-type printer interface. A CPU can read the status of the asynchronous communications element (ACE) interfaces at any point in the operation. The status includes the state of the modem signals (CTS, DSR, RLSD, and RI) and any changes to these signals that have occurred since the last time they were read, the state of the transmitter and receiver including errors detected on received data, and printer status. The TL16C451 and TL16C452 provide control for modem signals (RTS and DTR), interrupt enables, baud rate programming, and parallel-port control signals.