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

time slice
quantum
time quantum

    (Or "time quantum", "quantum") The period
   of time for which a process is allowed to run uninterrupted in
   a pre-emptive multitasking operating system.

   The scheduler is run once every time slice to choose the
   next process to run.  If the time slice is too short then the
   scheduler will consume too much processing time but if it is
   too long then processes may not be able to respond to external
   events quickly enough.

   (1998-11-06)