VSCM
A highly portable implementation of Scheme, written in ANSI C and Scheme. VSCM features exception and interrupt handling, executable portable memory images, coroutines and continuations with multiple arguments.
Portability is achieved by exclusive use of legal ANSI C features.
Version II Nov9 by Matthias Blume <blume@cs.princeton.edu> included run-time support and a bytecode compiler. It conforms to R4RS and IEEE P1178 and runs on Unix and Macintosh.
VSCM is no longer actively developed - the author recommends StandardML.