sentence: its design was heavily influenced by work on the modula-2+ language in use at src and at the acorn computers research center ( arc , later orc when olivetti bought out acorn ) at the time , which was the language in which the operating system for the dec firefly multiprocessor vax workstation was written and in which the acorn compiler for acorn modula-2 extended language ( camel ) at arc for the arx operating system project of arm based acorn archimedes range of computers were written .