2.1. OSCI SystemC IEEE 1666

The development of SystemC as a standard for modeling hardware started in 1996. Version 2.0 of the proposed standard was released by the Open SystemC Initiative (OSCI) in 2002. In 2006, SystemC became IEEE standard 1666-2005 [14].

Most software languages are not particularly suited to modeling hardware systems^[1]. SystemC was developed to provide features that facilitate hardware modeling, in particular to model the parallelism of hardware, in a mainstream programming language.

An important objective was that software engineers should be comfortable with using SystemC, even though it is a hardware modeling language. Rather than invent a new language, SystemC is based on the existing C++ language. SystemC is a true super-set of C++, so any C++ program is automatically a valid SystemC program.

SystemC uses the template, macro and library features of C++ to extend the language. The key features it provides are:

A C++ class, sc_module, suitable for defining hardware modules containing parallel processes.

	Note
	Process is a general term in SystemC to describe the various ways of representing parallel flows of control. It has nothing to do with processes in the Linux or Microsoft Windows operating systems.

A mechanism to define functions modeling the parallel threads of control within sc_module classes;
Two classes, sc_port and sc_export to represent points of connection to and from a sc_module;
A class, sc_interface to describe the software services required by a sc_port or provided by a sc_export;
A class, sc_prim_channel to represent the channel connecting ports;
A set of derived classes, of sc_prim_channel, sc_interface, sc_port and sc_export to represent and connect common channel types used in hardware design such as signals, buffers and FIFOs; and
A comprehensive set of types to represent data in both 2-state and 4-state logic.

The full specification is 441 pages long [14]. The OSCI reference distribution includes a very useful introductory user guide and tutorial [22].

^[1] There are some exceptions, most notably Simula67, one of the languages which inspired C++. In some respects it is remarkably like SystemC.