The Parallel Virtual Machine (PVM) documentation will tell you that "PVM is a software system that enables a collection of heterogeneous computers to be used as a coherent and flexible concurrent computational resource.  The individual computers may be shared-or local-memory multiprocessors, vector supercomputers, specialized graphics engines, or scalar workstations, that may be interconnected by a variety of networks, such as ethernet, FDDI.  User programs written in C, C++ or Fortran access PVM through library.  Daemon programs provide communication and process control between computers."

Because our supercomputer is no longer functional, we attempt to provide our programs with comparable computing power by spreading processor-intensive tasks over multiple machines in the lab.  My project is a modified version of my Mandelbrot program.  When it comes time to calculate the Mandelbrot set for the given region, the master task spawns a number of slave tasks multiple computers.  Each task is sent a row to do the calculations for; when it finishes, it sends the results back and receives another from the master program.   Otherwise, the program is functionally equivalent to its single-machine counterpart.

See the code for the master and slave programs.