Xerox Daybreak (a.k.a. Xerox 6085 PCS, Xerox 1186) is a workstation computer marketed by Xerox from 1985 to 1989. It ran the ViewPoint (later GlobalView) GUI and was used extensively throughout Xerox until being replaced by Suns and PCs. Despite being years ahead of its time it was never a major commercial success. The proprietary closed architecture and Xerox's reluctance to release the Mesa development environment for general use stifled any 3rd party development.