GNU Cim is a compiler for the programming language Simula (except
unspecified parameters to formal or virtual procedures (see the
documentation for how portable code for formal procedures can be
written)).  It offers a class concept, separate compilation with full
type checking, interface to external C routines, an application
package for process simulation and a coroutine concept.

The portability of the GNU Simula Compiler is based on the C
programming language.  The compiler and the run-time system is written
in C, and the compiler produces C code, that is passed to a C compiler
for further processing towards machine code.