Abstract-Today many of the high performance embedded processors already contain multiple processor cores and we see heterogeneous manycore architectures being proposed. Therefore it is very desirable to have a fast way to explore various heterogeneous architectures through the use of an architectural design space exploration tool, giving the designer the option to explore design alternatives before the physical implementation.In this paper, we have extended Heracles, a design space exploration tool for (homogeneous) manycore architectures, to incorporate different types of processing cores, and thus allow us to model heterogeneity. Our tool, called the Heterogeneous Heracles System (HHS), can besides the already supported MIPS core also include OpenRISC cores. The new tool retains the possibility available in Heracles to perform register transfer level (RTL) simulations of each explored architecture in Verilog as well as synthesizing it to field-programmable gate arrays (FPGAs). To facilitate the exploration of heterogeneous architectures, we have also extended the graphical user interface (GUI) to support heterogeneity. This GUI provides options to configure the types of core, core settings, memory system and network topology.Some initial results on FPGA utilization are presented from synthesizing both homogeneous and heterogeneous manycore architectures, as well as some benchmark results from both simulated and synthesized architectures.