Abstract : The paper describes a pragmatic solution to the parallel execution of hard real-time tasks on off-the-shelf embedded multiprocessors. We propose a simple timing isolation protocol allowing computational tasks to communicate with hard real-time ones. Excellent parallel resource utilization can be achieved while preserving timing compositionality. An extension to a synchronous language enables the correct-by-construction compilation to efficient parallel code. We do not explicitly address certification issues at this stage, yet our approach is designed to enable full system certification at the highest safety standards, such as SIL 4 in IEC 61508 or DAL A in DO-178B.