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

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