The Free On-line Dictionary of Computing (30 December 2018):

16450

    A UART with a one-byte FIFO buffer.  The 16450
   is a higher speed, fixed version of the 8250.  It was
   superseded by the 16550.

   The 16450 was used for the IBM PC AT and PS/2 but will not
   work in a IBM PC XT.

   (2004-03-21)