OS 2200 is the operating system for the Unisys ClearPath Dorado family of mainframe systems. 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 the 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. Unisys stopped producing ClearPath Dorado hardware in the early 2010s, and the operating system is now run under emulation.
History
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. Along with this new hardware came the operating system Exec 8 (Executive System for the 1108).
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. However, UNIVAC planned to offer symmetric multiprocessor versions of the 1108 with up to 4 processors and the earlier operating systems (really basic monitor programs) weren't designed for that, even though they supported limited multiprogramming.
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. The name OS 1100 was retained until 1988 with the introduction of the Sperry 2200 Series as a follow on to the 1100 Series when its name was changed to OS 2200. Since that time, the 2200 Series became the Unisys ClearPath IX Series and then the Unisys ClearPath Dorado Series, but the operating system retained the OS 2200 name.
The company name and its product names also changed over time. Engineering Research Associates (ERA) of Saint Paul was acquired by Remington Rand Corporation. Remington Rand also acquired the Eckert–Mauchly Computer Corporation of Philadelphia which was then building the UNIVAC computer. The two were combined into the UNIVAC division of Remington Rand under the direction of William Norris. William Norris had been one of the founders of ERA and later left Remington Rand to start Control Data Corporation. The UNIVAC division of Remington Rand Corporation became the UNIVAC division of Sperry Rand Corporation after Remington Rand merged with Sperry Corporation. In the 1970s Sperry Rand began a corporate identity program that changed its name to Sperry Corporation and all the division names to begin with Sperry, so the computer systems division became Sperry UNIVAC. Later the division names were dropped and everything simply became Sperry.
The operating system kernel is still referred to as "the Exec" by most Unisys and customer personnel. However, when Unisys began releasing suites of products tested together as system base releases, later called "ClearPath OS 2200 Release n", the term OS 2200 changed to refer to the entire suite of products in the system release and others, such as BIS, released asynchronously for the Dorado hardware platforms.
In 1986 Burroughs and Sperry corporations merged to become Unisys (which some long time 2200 Series clients say stands for "UNIVAC Is Still Your Supplier"). The major mainframe product lines of both companies have continued in development including the MCP Operating System from Burroughs and OS 2200 from Sperry.
In 2016 Unisys made a virtual Microsoft Windows version of OS2200 available at no cost for educational and leisure purposes.
Exec 8
EXEC 8 (sometimes referred to as EXEC VIII) was UNIVAC's operating system developed for the UNIVAC 1108 in 1964. It combined the best features of the earlier operating systems, EXEC I and EXEC II, which were used on the UNIVAC 1107. EXEC 8 was one of the first commercially successful multiprocessing operating systems. It supported simultaneous mixed workloads comprising batch, time-sharing and real-time. Its one file system had a flat naming structure across many drums and spindles. It also supported a well-received transaction processing system.
Previous systems were all real-mode systems with no hardware support for protection and separation of programs and the operating system. While there had been support for multiprogramming in previous systems, it was limited to running one user job concurrently with multiple supporting functions known to be well-behaved, such as the card reader, printer, and card punch spoolers.