Computing at CERN

Wim Klein, CERN's first computer

1 January 1958

Before electronic computers were available at CERN, a Dutchman called Willem "Wim" Klein performed astonishing feats of mental arithmetic to help his colleagues with their calculations.

Klein was born in Amsterdam in the Netherlands on 4 December 1912. He first displayed his mathematical talents in circuses around Europe. He joined CERN's Theory Division in 1958, where he was in considerable demand as a calculator in the days before the first electronic computers.

On 27 August 1976, Klein calculated the 73rd root of a 500-digit number in 2 minutes and 43 seconds, a feat recorded by the Guinness Book of Records. He became known as "the human computer".

Klein was found dead in his home in Amsterdam on 1 August 1986. He had been stabbed to death. The killer was never identified.

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Computing at CERN

CERN installs its first electronic computer: The Ferranti Mercury

30 June 1958

CERN's first computer, a huge vacuum-tube Ferranti Mercury, was installed in 1958. It was one million times slower than today's large computers. Though the Mercury took 3 months to install – and filled a huge room – its computational ability didn't quite match that of a modern pocket calculator. "Mass" storage was provided by four magnetic drums each holding 32K × 20 bits – not enough to hold the data from a single proton-proton collision in the Large Hadron Collider. The Mercury ran a simplified coding system called Autocode – a type of programming language with a limited repertoire of variables. 

At the end of its career the Mercury was connected online to the Missing Mass Spectrometer experiment. In 1966 it was shipped to Poland as a gift to the Academy of Mining and Metallurgy at Cracow. Although it was quickly taken over by transistor-equipped machines, a small part of the Mercury remains in the CERN IT department. The computer's engineers installed a warning bell to signal computing errors – the bell is mounted on the wall in a corridor of building 2.

See video: "Computing at CERN in 1965" (features the Ferranti Mercury)

Technical specifications

Ran at CERN from 1958 to 1965
First generation vacuum tube machine
60-microsecond clock cycle, 2 cycles to load or store, 3 cycles to add and 5 cycles to multiply 40-bit longwords
No hardware division
Magnetic core storage (1024 40-bit words, 120-microsecond access time)
Processor with floating-point arithmetic and a B-Register (an index register)
Magnetic-drum auxiliary storage (16 Kwords of 40 bits, 8.75 msec average latency, 64 longwords transferred per revolution)
Paper tape I/0
Two Ampex magnetic-tape units added in 1962
Autocode compiler


Computing at CERN

CERN inaugurates the IBM 709

6 March 1961

The IBM 709 arrived at CERN in January 1961. It was inaugurated at an official ceremony on 6 March that year, where computer engineer Lew Kowarski delivered a speech (see image).

With Mercury and the 709 operating together, CERN had its first experience of compatibility problems. This was a continuing source of difficulty as various different computers came into operation at CERN.  Many of CERN's programs were also used on a range of computers in its 13 member states. 

A high-level computer-programming language called "FORTRAN" (short for "FORmula TRANSlating")that made its CERN debut with the 709, and this language quickly became the only programming language in general use at the laboratory. A new generation of programs, written in FORTRAN to exploit the greater speed of the IBM 709, were brought in to analyse measurements from bubble-chamber photographs. 

The IBM 709 was a vacuum-tube machine with a core memory size of 32K 36-bit words. The central processing unit (CPU) was 4-5 times faster than that of the Mercury, but compiling a typical FORTRAN program could still take several minutes. Tape bins made way for card trays. As many as six peripheral devices could be attached via their controllers to data channels on the 709, to access core memory buffers while the CPU performed other work. The Direct Data Connection – an innovation of the machine – allowed for direct transmission of data from external equipment to memory via a channel. The speed was in principle up to 1 megabit per second.

After one year of experience, CERN added a small IBM 1401 to speed up the input/output, job sequencing and operations. The concept of SPOOLing (Simultaneous Peripheral Operation On-Line) with its 1/0 files (virtual reader/printer) has its origins in the days of 709 operations.

Technical specifications
IBM 709
Ran at CERN from 1961 to 1963
Vacuum-tube machine
12-microsecond clock cycle, 2 cycles to add and 15 on average to multiply 36-bit integers
Hardwired division and floating-point arithmetic, index registers
Core storage: 32K words of 36 bits, 24-microsecond access time
Card reader (250 cards per minute) and card punch (100 cards per minute)
Line printer
Magnetic-tape units (7 tracks, 75 inches written per second at 200 bytes per inch)
Introduction of the Data Channel
FORTRAN compiler
FORTRAN monitor system


Computing at CERN

Just add "0": The IBM 7090 replaces the IBM 709

15 September 1963

The IBM 7090 was installed at CERN in 1963. It was about four times more powerful than the 709. The computer was connected to a device call a Hough-Powell digitizer (HPD) – a machine that scanned films from bubble chambers, measured important tracks, and sent the information directly to the 7090. A second device, "Luciole", was also connected to the computer, providing fully automatic measurements from spark-bubble chambers. Over 300,000 frames of spark-chamber film were automatically scanned and measured in this way, beginning the trend towards online use of computers for processing experimental data. 

Technical specifications
IBM 7090
Ran at CERN 1963 to 1965
Transistorized second-generation machine with a 2.18-microsecond clock cycle
Core storage: 32K words of 36 bits, 4.36-microsecond access time
Card 1/0, Tape units wrote on 7 tracks at 112.5 inches per second, 200 to 556 bytes per inch
8 data channels
Interrupt system
FORTRAN compiler
Basic monitor operating system (IBSYS)
Connected online to flying-spot digitizers (HPD and Luciole) to measure bubble and spark chamber films


Computing at CERN

The CDC 6600 arrives at CERN

14 January 1965

The CDC 6600, made by the Control Data Corporation, arrived at CERN on 14 January 1965. It was the first multi-programmed machine in the CERN Computer Centre, with about 10 times the processing capacity of the IBM 7090. 

The 6600 was used to analyse the 2-3 million photographs of bubble-chamber tracks that CERN experiments were producing every year. Human operators recorded significant observations from frames of bubble-chamber film onto punched cards. A machine called a  Hough-Powell digitizer (HPD) scanned the cards and sent the information to the 6600. A device called YEP also measured significant tracks on bubble-chamber photographs, coded them onto paper tape, and sent this information to the computer. A third device – "Luciole" –  provided the 6600 with fully automated measurements of spark-chamber film. 

The CDC 6600 filled a large room. It consisted of 12 data channels, 10 peripheral processors, a central magentic-core memory and a central processor. Devices such as the HPD were connected directly to the computer by data channels. The 6600 was also connected to card readers that ran about 500 FORTRAN problems per day, and to two online computers – the SDS920 and the IBM 1800 – via CERN-made data links. The results of calculations on the 6600 were printed on paper or punched onto cards for further study.

The change-over from the IBM 7090 was planned to take 3 months starting in January 1965. Major engineering overhauls were needed during the first few years, which led to a 2-month shut-down in 1968 to modify the 6600: CERN's pre-production model needed to incorporate the logic and packaging improvements that had been introduced in CDC's production machines. During this period of struggling with hardware instability and software development, computing work at CERN was done partly by sending jobs to outside computers and partly by processing data on a CDC 3400, and later on a 3800, temporarily made available by the Control Data Corporation.

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Technical specifications

CDC 6600, serial number 3 (pre-production series machine)
Ran at CERN from 1965 to 1975
Transistor machine
Central Processing Unit clock cycle: 100 nanoseconds
Core memory: 128K words of 60 bits (converted to modern terms, with 8-bit bytes, this is 0.94 MB)
Memory access: 1 microsecond (but independent memory banks allowed for up to one access per clock cycle)
Instruction prefetch function
Ten overlapping functional units
Ten autonomous peripheral processor units (PPU's) each with 4K 12-bit words of core memory
Huge disks over 1 metre in diameter held 500 million bits each
Tape units (half inch tape: 7 tracks, recording 200, 556 and 800 bytes per inch; one-inch tape: 14 tracks recording 800 bytes per inch)
High-speed card reader (1200 cards per minute)


Computing at CERN

The CDC 3800 boots up temporarily

10 August 1966

The 3800 was a member of the 3000 series Control Data Corporation family of computers, incompatible with the 6000 series machines. The 3800 had a 48-bit architecture. Its 64 Kword core memory was replaced by a faster, 800-nanosecond memory during its stay at CERN. This machine was eventually acquired by the State of Geneva and installed at the local University of Geneva. At CERN it was replaced by a CDC 6400. It is worth noting that CERN acquired other machines of the 3000 series, such as a 3100 for the FOCUS project offering semi-interactive facilities and quick sampling of experimental data at the central computers, and a 3200 for interactive graphics applications.

Computing at CERN

The Finance Committee approves the purchase of a CDC 6400

16 February 1967

At its 81st meeting on 16 February 1967, CERN's Finance Committee authorized the purchase of the CDC 6400 computer, a small CDC 3100, and four magnetic tape units. The costs exceeded the funds available in the 1967 budget by 7-8 million Swiss francs. In its next meeting the Committee recommended the use of CERN's own funds for the purchase, "only raising a bank overdraft if this is necessary to cover the cash requirements". 

The CDC 6400 was installed at CERN later that year. 

Computing at CERN

The 6400 is ugraded to a 6500

8 April 1969

The CDC 6400 was upgraded to a CDC 6500 in 1969. This image, taken on 12 February 1974, shows a general view of the remote input/output station installed in building 112, used for submitting jobs to the CDC 6500 and 6600. The card reader on the left and the line printer on the right are operated by programmers on a self-service basis.

Computing at CERN


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