Chippewa Operating System

The Chippewa Operating System often called COS is the discontinued operating system for the CDC 6600 supercomputer, generally considered the first super computer in the world. The Chippewa was initially developed as an experimental system, but was then also deployed on other CDC 6000 machines. 
The Chippewa was a rather simple job control oriented system derived from the earlier CDC 3000 which later influenced Kronos and SCOPE. The name of the system was based on the Chippewa Falls research and development center of CDC in Wisconsin.
This operating system at Control Data Corporation was distinct from and preceded the Cray Operating System (also called COS) at Cray.