These directories contain sources in Ratfor from the Kernighan and
Plaugher book Software Tools as I implemented it on two platforms more
years ago that I care to remember:  Perkin-Elmer and VAX VMS.

Ratfor is history as C is victorious as THE systems implementation
language and weird machines with 28 bit words and that sort of thing
are a thing of the past. I think even the Perkin-Elmer machines are
history. So these sources are here for historical interest.  If you are
still using Ratfor, there is a nice diff (that doesn't come from K+P)
that I translated from the Unix implementation.