The Cray Operating System (COS) succeeded Chippewa Operating System (shipped with earlier computer systems CDC 6000 series and CDC 7600) and was Cray Research's proprietary operating system for its Cray-1 (1976) and Cray X-MP supercomputers, and those platforms' main OS until replaced by UNICOS in the late 1980s. COS was delivered with Cray Assembly Language (CAL), Cray FORTRAN (CFT), and Pascal.