 The combination of superscalar processing and speculative execution delivered a tangible performance increase on existing bodies of code – which were mostly written in Pascal, Fortran, C and C++.Given these substantial and regular performance improvements to existing code there was little incentive to rewrite software in languages or coding styles which expose more task-level parallelism.Nevertheless, the model of cooperating concurrent processors can still be found in cluster computing systems that dominate supercomputer design in the 21st century.