{{Infobox information appliance , name = Electrologica X8 , title = , aka = EL X8 , logo = , logo caption = , image = Electrologica X8.jpg , image_size = , caption = EL X8 on display at

Museum Boerhaave Rijksmuseum Boerhaave is a museum of the history of science and medicine, based in Leiden, Netherlands. The museum hosts a collection of historical scientific instruments from all disciplines, but mainly from medicine, physics, and astronomy. Th ...

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Electrologica N.V. Electrologica was a pioneering Dutch computer manufacturer from 1956 to 1968, when it was taken over by Philips. It was started by A. van Wijngaarden, B.J. Loopstra and C.S. Scholten from the Mathematisch Centrum (Mathematical centre) in ...

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Mainframe computer A mainframe computer, informally called a mainframe or big iron, is a computer used primarily by large organizations for critical applications like bulk data processing for tasks such as censuses, industry and consumer statistics, enterpris ...

, generation = , release date = {{Start date and age, 1964 , lifespan = , price = , discontinued = {{End date and age, 1968 , units sold = , unitsshipped = , media = , os =

THE multiprogramming system The THE multiprogramming system or THE OS was a computer operating system designed by a team led by Edsger W. Dijkstra, described in monographs in 1965-66 (Jun 14, 1965) and published in 1968. Dijkstra never named the system; "THE" is simply ...

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Electrologica X1 The Electrologica X1 was a digital computer designed and manufactured in the Netherlands from 1958 to 1965. About thirty were produced and sold in the Netherlands and abroad. The X1 was designed by the Mathematical Centre in Amsterdam, an academ ...

, successor = , related = , website = The Electrologica X8 (or EL X8) was a digital computer designed as a successor to the

and manufactured in the Netherlands by

NV between 1964 and 1968. Like its predecessor, the X1, the X8 system included

core memory Core or cores may refer to: Science and technology * Core (anatomy), everything except the appendages * Core (manufacturing), used in casting and molding * Core (optical fiber), the signal-carrying portion of an optical fiber * Core, the central ...

, 27-bit word length, and

drum memory Drum memory was a magnetic data storage device invented by Gustav Tauschek in 1932 in Austria. Drums were widely used in the 1950s and into the 1960s as computer memory. For many early computers, drum memory formed the main working memory ...

as secondary storage (not as primary storage). The memory address was increased from 15 to 18 bits, for a theoretical maximum memory size of 256k words. The X8 included an independent peripheral processor called CHARON (Centraal Hulporgaan Autonome Regeling Overdracht Nevenapparatuur, or Central Coprocessor Autonomous Regulation Transfer Peripherals) which handled I/O. Other features included up to 48 input/output channels designed for low speed devices such as paper tape, plotters and printers. Unlike the X1, the arithmetic unit of the X8 included

floating point arithmetic In computing, floating-point arithmetic (FP) is arithmetic that represents real numbers approximately, using an integer with a fixed precision, called the significand, scaled by an integer exponent of a fixed base. For example, 12.345 can be r ...

, with a 41-bit mantissa and 12-bit exponent (which adds up to 53 bits rather than 54; the reason is that there are two copies of the mantissa sign bit). The system is most notable as the target processor for

Edsger Dijkstra Edsger Wybe Dijkstra ( ; ; 11 May 1930 – 6 August 2002) was a Dutch computer scientist, programmer, software engineer, systems scientist, and science essayist. He received the 1972 Turing Award for fundamental contributions to developing progra ...

's implementation of the

. This includes the invention of semaphores, enabled by a specific instruction in the X8 instruction set. Semaphores were used not only as a synchronization mechanism within the THE operating system, but also in the request and response data structures for I/O requests processed by the CHARON coprocessor.

References

* E.W.Dijkstra, ''Documentatie over de communicatie apparatuur aan de EL X8'', EWD140, undated.

* E.W.Dijkstra, ''Globale beschrijving van de drijvende arithmetiek van de EL X8'', EWD145, 6 December 1965

* E.W. Dijkstra, "The structure of the 'THE' multiprogramming system", ''Communications of the ACM'' 11(5):341–346, 1968
Dijkstra's manuscript EWD196Full text (subscription)

External links

Mainframe computers Dutch inventions Science and technology in the Netherlands Computer science in the Netherlands Computers designed in Europe