Micro-C++. A extension of
C++, by Peter A Ruhr
of the University of Waterloo, with light-weight concurrency coroutines and mutual exclusion.
Version 3.7 for Unix uses GCC 2.3.3 and requires dmake 3.0+ and the setitimer and sigcontext library calls. It runs on Sequent, Sun-4, Sun-3, Ultrix, SGI, RS/6000, HP-PA.
(ftp://plg.uwaterloo.ca/pub/uSystem/u++-3.7.tar.Z).
[Software--Practice and Experience, 22(2):137-172, February 1992].