NATIONAL SEMICONDUCTOR'S PC PERIPHERALS APPLICATION GROUP

                             USER INFORMATION

                             PC16C550/NS16550AF

                                  8/9/90




       When the transmitter FIFO is enabled, the last byte in

       the shift register is being sent out, and only 1 new byte

       is being loaded into this FIFO; there is a small

       posssibility that the new byte will not be transmitted.

       When more than 1 new byte is loaded into the FIFO all of

       the new bytes loaded will be transferred.



       This issue is caused by the timing relationship between

       the baudrate and the system software. If this problem

       occurs it can be eliminated by changing the execution

       time of the driver software.