The Xerox Operating System (XOS) was an operating system for the XDSSigma series of computers "optimized for direct replacement of IBMDOS/360 installations" and to provide real-time and timesharing support.[1]
The system was developed, beginning in 1969, for Xerox by the French firm CII (now Bull).[2]
XOS was more successful in Europe than in the US, but was unable to compete with IBM. By 1972 there were 35 XOS installations in Europe, compared to 2 in the US.[1]
