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

IBM PC XT
XT

    An IBM PC with a (slow) hard disk.  The XT was
   released in March 1983.  It had an Intel 8088 CPU.  The
   XT/370, released in October 1983, added IBM 370 mainframe
   emulation, and the XT 286 followed in September 1986 with an
   Intel 80286 CPU [Why?].

   (1996-05-21)