This application is described in the article "CThreads: Weaving Your App" in the July 1990 issue (#8) of Next Users' journal.
Just type "make", and start crankin' out them Primes!
David S. Joerg
MindShock, Inc.
Internet : joerg@alliant.mcs.anl.gov (until September)
p.s. Applications demonstrating more sophisticated use of threads may be forthcoming, it all depends on various random factors. Be warned that this is just an introductory-level example.