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

8250

    A UART that can operate at a maximum of 9600 baud.

   The 8250 is used in IBM PC XT computers.  It works in an
   IBM PC AT under DOS but generates unwanted interrupts
   when used at 9600 baud.  The IBM PC BIOS has a bug fix
   for this chip.

   (2004-03-21)