As integration of a whole system on a chip becomes possible, the need for fast and precise simulation tools increases. We present a high speed cycle precise simulation environment dedicated to core based embedded systems. We show that for the type of systems we aim at simulating, a correct simulation is obtained without event propagation. This restricted set of systems is suitable for embedded core based ASICs, and can be simulated at very high speed, since a single evaluation is necessary per cycle. For a sample system including a MIPS around a PI-Bus, simulation rates of 120,000 cycles per second are achieved on a SS10/51.