The Collaborative International Dictionary of English v.0.48:

Ep- \Ep-\ ([e^]p-). [Gr. 'epi`.]
   See Epi-.
   [1913 Webster]

The Free On-line Dictionary of Computing (19 January 2023):

Emulator program
EP

    (EP) IBM software that emulates a 2701/2/3
   hard-wired IBM 360 communications controller and resides in
   a 370x/372x/374x comms controller.

   See also Partitioned Emulation Program (PEP).

   (1999-01-29)