Systems-on-Chip (SoCs) are heterogeneous by nature as they may integrate digital, analog, RF hardware as well as software components or non electrical parts such as sensors or actuators. The increasing level of complexity for designing SoCs in a reasonable amount of time and resources asks, among other capabilities, for powerful modeling and simulation means. SystemC is emerging as a de facto standard for digital system design, but is still lacking a standard support of continuous-time and mixed discrete-event/continuous-time systems. This paper presents the first elements of extensions to SystemC, called SystemC-AMS, that are proposed to fill the gap.