The ST16C2552 is a dual asynchronous receiver and transmitter with 16 byte transmit and receive FIFOs. Independent programmable baud rate generators are provided to select transmit and receive clock rates from 50Hz to 1.5 MHz for each UART. The on board status registers of the ST16C2552 provide the error conditions, type and status of the transfer operation being performed. Complete MODEM control capability and a processor interrupt system that may be software tailored to the user's requirements are included. The ST16C2552 provides internal loop-back capability for on board diagnostic testing.