Universal Time-Sharing System

The Universal Time-Sharing System, known as UTS, was an operating system built by Xerox Data Systems (originally Scientific Data Systems) for the Sigma series of computers. It succeeded the earlier Batch Processing Monitor and Batch Time-Sharing Monitor, and although it was announced in 1966, implementation delays kept it from shipping until 1971. UTS was designed to provide multi-programming services for interactive online users alongside batch production jobs, spooled input and output, and time-critical real-time processing, using background daemon-like ghost jobs to run monitor code in user space. Its final version, D00, appeared in January 1973, after which its capabilities were folded into the CP-V operating system alongside the batch-oriented Xerox Operating System.