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

IBM PCjr
PCjr

    (IBM PC Junior) A floppy disk-based home
   computer with an Intel 8088 CPU and a chiclet keyboard,
   released in November 1983.  The PCjr could be expanded to have
   two floppy drives and 640 kilobytes of RAM using sidecars.
   Some even had a mouse and could run drawing programs with
   popup menus.

   (1995-10-06)