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Regnecentralen (RC) was the first Danish computer company, founded on 12 October 1955. Through the 1950s and 1960s, they designed a series of computers, originally for their own use, and later to be sold commercially. Descendants of these systems sold well into the 1980s. They also developed a series of high-speed paper tape machines, and produced Data General Nova machines under license.
What would become RC began as an advisory board formed by the Danish Akademiet for de Tekniske Videnskaber (Academy of Applied Sciences) to keep abreast of developments in modern electronic computing devices taking place in other countries. It was originally named Regnecentralen, Dansk Institut for Matematikmaskiner (Danish Institute of Computing Machinery [1] ) After several years in the advisory role, in 1952 they decided to form a computing service bureau for Danish government, military and research uses. Led by Niels Ivar Bech, the group was also given the details of the BESK machine being designed at the Swedish Mathematical Center (Matematikmaskinnämndens Arbetsgrupp).
The group decided to build their own version of the BESK to run the bureau, and formed Regnecentralen in October 1955 to complete and run the machine. The result was the DASK, a vacuum tube-based machine that completed construction in 1956 and went into full operation in February 1957. DASK was followed in 1961 by the fully transistorized GIER, used for similar tasks. GIER is an acronym for "Geodætisk Instituts Elektroniske Regnemaskine" (Institute of Geodetics Electronic Calculator) and was introduced there on 14 September 1961. GIER proved to be a useful machine, and went on to be used at many Danish universities. Bech also sold GIER machines to the Eastern Bloc nations, starting with Czechoslovakia, Hungary, Poland and Bulgaria, and later Romania, the East Germany, and Yugoslavia.
RC was also home to Peter Naur, and DASK and GIER became well known for their role in the development of the famous programming language ALGOL. After the first European ALGOL conference in 1959, RC began an effort to produce a series of compilers, completing one for the DASK in September 1961. A version for the GIER followed in August 1962. Christian Andersen and Peter Schyum Poulsen, another RC employee, wrote the first introductory text on the language, Everyman's Desk ALGOL, in 1961.
To support higher throughput at their own service bureau, RC developed several high-speed input/output devices. One of their most popular was the RC 2000 paper tape reader, introduced in 1963. Feeding the tape at 5 meters per second, the 2000 could read 2,000 characters per second (CPS), storing the results in a buffer while the computer periodically read the data back out instead of stopping the tape to wait for the computer to get ready. The machine was later upgraded as the RC 2500, increasing speed to almost 7 meters a second, improving read speed to 2500 CPS. The RC 2000/2500 became a major product for RC during the 1960s, selling 1,500 examples around the world. Several related devices were added to the line, including a high-speed punch and a dedicated data conversion machine that would "massage" data between formats to ease the burden on the host computer.
In 1964 Regnecentralen was taken public. Most of the firm's shares were held by its biggest customers.
In the mid-1960s, RC began the design of a small integrated circuit-based computer system for industrial control and automation needs, initially to fill a request by a Danish company to automate a chemical factory they were building in Poland. The RC 4000 design emerged in 1966 and was completed for the factory the next year. When combined with appropriate peripherals, almost always including an RC 2000 along with several rebranded devices from other companies, the RC 4000 was a highly reliable minicomputer, and went on to be sold across Europe. The RC 8000 from the mid-1970s used newer-generation integrated circuits (ICs) to shrink the RC 4000 into a single rack-mount system. The last in the series, the RC 9000, further shrunk the machine and improved performance to about 4 MIPS, and was sold in versions that could run either RC 8000 programs, or Unix.
The RC 4000 is famous for its operating system, developed by Per Brinch Hansen. [2] Known as the RC 4000 multiprogramming system, it is the first real-world example of a system using a very simple kernel along with a variety of user-selected programs that built up the system as a whole. [3] Today this concept is known as a microkernel, [4] and efforts to correct for microkernels' poor performance formed the basis of most OS research through the 1970s and 1980s. Brinch Hansen also worked with Charles Simonyi and Peter Kraft on the RC 4000's Real-time Control System. [5]
RC also began selling the Data General Nova under license in 1970 as the RC 7000, later introducing their own updated version as the RC 3600 the next year. This series filled a niche similar to the RC 4000, but for much smaller installations. The RC 3600 became a fixture of many Danish schools and universities.
During the 1980s, RC produced the RC700 Piccolo, the RC750 Partner, and the RC759 Piccoline systems, which were sold to Danish schools mostly, and to some businesses in Denmark and abroad. The Piccolo was powered by the Zilog Z80A CPU, while the Piccoline was powered by the Intel 80186 processor.
In 1988, International Computers Limited (ICL) acquired a 50% stake in Regnecentralen, then trading as RC Computer, with the intention of merging the business into ICL Denmark. [6] However, the business persisted as a distinct operational entity under the RC International name. [7]
In computer science, a microkernel is the near-minimum amount of software that can provide the mechanisms needed to implement an operating system (OS). These mechanisms include low-level address space management, thread management, and inter-process communication (IPC).
In distributed computing, a remote procedure call (RPC) is when a computer program causes a procedure (subroutine) to execute in a different address space, which is written as if it were a normal (local) procedure call, without the programmer explicitly writing the details for the remote interaction. That is, the programmer writes essentially the same code whether the subroutine is local to the executing program, or remote. This is a form of client–server interaction, typically implemented via a request–response message passing system. In the object-oriented programming paradigm, RPCs are represented by remote method invocation (RMI). The RPC model implies a level of location transparency, namely that calling procedures are largely the same whether they are local or remote, but usually, they are not identical, so local calls can be distinguished from remote calls. Remote calls are usually orders of magnitude slower and less reliable than local calls, so distinguishing them is important.
Peter Naur was a Danish computer science pioneer and 2005 Turing award winner. He is best remembered as a contributor, with John Backus, to the Backus–Naur form (BNF) notation used in describing the syntax for most programming languages. He also contributed to creating the language ALGOL 60.
BESK was Sweden's first electronic computer, using vacuum tubes instead of relays. It was developed by Matematikmaskinnämnden and for a short time it was the fastest computer in the world. The computer was completed in 1953 and in use until 1966. The technology behind BESK was later continued with the transistorized FACIT EDB and FACIT EDB-3 machines, both software compatible with BESK. Non-compatible machines highly inspired by BESK were SMIL made for the University of Lund, SAABs räkneautomat SARA, "SAAB's calculating machine", and DASK made in Denmark.
Per Brinch Hansen was a Danish-American computer scientist known for his work in operating systems, concurrent programming and parallel and distributed computing.
KDF9 was an early British 48-bit computer designed and built by English Electric. The first machine came into service in 1964 and the last of 29 machines was decommissioned in 1980 at the National Physical Laboratory. The KDF9 was designed for, and used almost entirely in, the mathematical and scientific processing fields – in 1967, nine were in use in UK universities and technical colleges. The KDF8, developed in parallel, was aimed at commercial processing workloads.
The Bendix G-15 is a computer introduced in 1956 by the Bendix Corporation, Computer Division, Los Angeles, California. It is about 5 by 3 by 3 feet and weighs about 966 pounds (438 kg). The G-15 has a drum memory of 2,160 29-bit words, along with 20 words used for special purposes and rapid-access storage. The base system, without peripherals, cost $49,500. A working model cost around $60,000. It could also be rented for $1,485 per month. It was meant for scientific and industrial markets. The series was gradually discontinued when Control Data Corporation took over the Bendix computer division in 1963.
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 and published in 1968. Dijkstra never named the system; "THE" is simply the abbreviation of "Technische Hogeschool Eindhoven", then the name of the Eindhoven University of Technology of the Netherlands. The THE system was primarily a batch system 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".
The LGP-30, standing for Librascope General Purpose and then Librascope General Precision, is an early off-the-shelf computer. It was manufactured by the Librascope company of Glendale, California, and sold and serviced by the Royal Precision Electronic Computer Company, a joint venture with the Royal McBee division of the Royal Typewriter Company. The LGP-30 was first manufactured in 1956, at a retail price of $47,000, equivalent to $530,000 in 2023.
The RC 4000 Multiprogramming System is a discontinued operating system developed for the RC-4000 minicomputer in 1969. For clarity, this article mostly uses the term Monitor.
The ICT 1301 and its smaller derivative ICT 1300 were early business computers from International Computers and Tabulators. Typical of mid-sized machines of the era, they used core memory, drum storage and punched cards, but they were unusual in that they were based on decimal logic instead of binary.
The DASK was the first computer in Denmark. It was commissioned in 1955, designed and constructed by Regnecentralen, and began operation in September 1957. DASK is an acronym for Dansk Aritmetisk Sekvens Kalkulator or Danish Arithmetic Sequence Calculator. Regnecentralen almost did not allow the name, as the word dask means "slap" in Danish. In the end, however, it was named so as it fit the pattern of the name BESK, the Swedish computer which provided the initial architecture for DASK.
The separation of mechanism and policy is a design principle in computer science. It states that mechanisms should not dictate the policies according to which decisions are made about which operations to authorize, and which resources to allocate.
Jørn Jensen was one of the earliest Danish computer programmers. Examined as a mechanical engineer, he had worked with electromechanical construction. In 1958, he was employed at the Danish Regnecentralen (RC), and very soon exhibited an extraordinary programming skill. He developed the main parts of the base programs to the Dansk Aritmetisk Sekvens Kalkulator, the first Danish computer. Among other programs, he designed a set of monitor programs to supervise the program running schedule on DASK. In tight collaboration with Peter Naur and others, he developed reliable, well documented compilers for the ALGOL 60 programming language. In this context, he invented Jensen's Device, an ingenious exploitation of the name parameters to compute numerical series without using procedure parameters, as is needed in all programming languages, except ALGOL 60 and Simula 67.
The English Electric System 4 was a mainframe computer announced in 1965. It was derived from the RCA Spectra 70 range, itself a variant of the IBM System 360 architecture.
The kernel is a computer program at the core of a computer's operating system and generally has complete control over everything in the system. The kernel is also responsible for preventing and mitigating conflicts between different processes. It is the portion of the operating system code that is always resident in memory and facilitates interactions between hardware and software components. A full kernel controls all hardware resources via device drivers, arbitrates conflicts between processes concerning such resources, and optimizes the utilization of common resources e.g. CPU & cache usage, file systems, and network sockets. On most systems, the kernel is one of the first programs loaded on startup. It handles the rest of the startup as well as memory, peripherals, and input/output (I/O) requests from software, translating them into data-processing instructions for the central processing unit.
ICT 1900 was a family of mainframe computers released by International Computers and Tabulators (ICT) and later International Computers Limited (ICL) during the 1960s and 1970s. The 1900 series was notable for being one of the few non-American competitors to the IBM System/360, enjoying significant success in the European and British Commonwealth markets.
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