Most source is available to clients under license. The operating system kernel of OS 2200 is a lineal descendant of Exec 8 for the UNIVAC 1108. Documentation and other information on current and past Unisys systems can be found on 1100 in binary option Unisys public support website.
See Unisys 2200 Series system architecture for a description of the machine architecture and its relationship to the OS 2200 operating system. There were earlier 1100 systems going back to the 1101 in 1951, but the 1108 was the first 1100 Series computer designed for efficient support of multiprogramming and multiprocessing. The UNIVAC 1108 computer was announced in 1964 and delivered in late 1965. The first 1108 computers used Exec I and Exec II, which had been developed for the UNIVAC 1107. When the UNIVAC 1110 was introduced in 1972, the operating system name was changed to OS 1100 to reflect its support for the wider range of systems.