You are probably right. Dont know where I got that idea from . Thanks
I found it
" The Cray Operating System (COS) is a Cray Research operating system for its now-discontinued Cray-1 (1976) and Cray X-MP supercomputers. It succeeded the Chippewa Operating System (shipped with earlier Control Data Corporation CDC 6000 series and 7600 computer systems), and was the Cray main OS until replaced by UNICOS in the late 1980s"
You are right.
I worked on a CDC 7600. It ran SCOPE OS.