THE multiprogramming system

For other uses, see THE (disambiguation).
THE multiprogramming system
Developer Technische Hogeschool Eindhoven / Edsger Dijkstra (et al.)
Written in Electrologica X8 assembly language
Working state Historic
Initial release 1968 (1968)
Platforms Electrologica X8

The THE multiprogramming system was a computer operating system designed by a team led by Edsger W. Dijkstra, described in monographs in 1965-66[1] and published in 1968.[2] Dijkstra never named the system; "THE" is simply the abbreviation of "Technische Hogeschool Eindhoven", then the name (in Dutch) of the Eindhoven University of Technology of the Netherlands. The THE system was primarily a batch system[3] that supported multitasking; it was not designed as a multi-user operating system. It was much like the SDS 940, but "the set of processes in the THE system was static".[3]

The THE system apparently introduced the first forms of software-based memory segmentation (the Electrologica X8 did not support hardware-based memory management),[3] freeing programmers from being forced to use actual physical locations on the drum memory. It did this by using a modified ALGOL compiler (the only programming language supported by Dijkstra's system) to "automatically generate calls to system routines, which made sure the requested information was in memory, swapping if necessary".[3]

Design

The design of the THE multiprogramming system is significant for its use of a layered structure, in which "higher" layers only depend on "lower" layers:

The constraint that higher layers can only depend on lower layers was imposed by the designers in order to make reasoning about the system (using quasi-formal methods) more tractable, and also to facilitate building and testing the system incrementally. The layers were implemented in order, layer 0 first, with thorough testing of the abstractions provided by each layer in turn. This division of the kernel into layers was similar in some ways to Multics' later ring-segmentation model. Several subsequent operating systems have used layering to some extent, including Windows NT and OS X, although usually with fewer layers.

The code of the system was written in assembly language for the Dutch Electrologica X8 computer. This computer had a word size of 27 bits, 32 kilowords of core memory,[3] 512 kilowords of drum memory providing backing store for the LRU cache algorithm, paper tape readers, paper tape punches, plotters, and printers.

See also

References

  1. Dijkstra, Edsger W. The structure of the 'THE'-multiprogramming system (EWD-196). E.W. Dijkstra Archive. Center for American History, University of Texas at Austin. (original; transcription) (Jun 14, 1965)
  2. Dijkstra, E.W. (1968), "The structure of the 'THE'-multiprogramming system", Communications of the ACM 11 (5): 341–346, doi:10.1145/363095.363143
  3. 1 2 3 4 5 Silberschatz, Abraham; Peterson, James L. (May 1988), "13: Historical Perspective", Operating System Concepts, p. 512
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