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

chunker
dechunker
split

    A program like Unix's "split" which breaks an
   input file into parts, usually of a pre-set size, e.g. the
   maximum size that can fit on a floppy.  The parts can then
   be assembled with a dechunker, which is usually just the
   chunker in a different mode.

   (1998-12-15)