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iSGTW Statistic of the Week - 250

Statistic of the Week - 250

CERN computer center operator at an IBM 370 in the early 1980s.
Image copyright CERN

In 1990 the CERN Computer Center contained less than 250 CERN Computing Units.

The CERN Unit of processing power was a standard proposed in 1985 by Eric McIntosh of the CERN computing division, then called "DD" for Data-handling Division. One CERN Unit (CU) corresponded to the power of a single CPU of an IBM 370 Model 168, or to that of a DEC Vax 8600. It was based on execution speed of a standard set of HEP code assembled by McIntosh. This code set was later incorporated as part of the SpecINT standard, a world measure for CPU power which is in general use today.

The CERN Unit was equivalent to about 4 Million floating point operations per second (i.e. 4 Mips), or roughly 2 units of the more modern SpecINT2000 standard.

The approximate 250 CERN Units in 1990 came primarily from the IBM complex (about 150 units), the Cray XMP-48 (about 50) and the biggest DEC Vax, the Model 9000 (contributing about 10).

Today any respectable desktop computer has a processing power of at least 1000 CERN Computing Units. Many thousands of such machines are clustered in today's Computer Center at CERN, providing the overall center at least 10 million CERN Computing Units.

McIntosh standardized the unit and compared computer speed around the world for a representative set of CERN jobs in his 1997 paper Benchmarking Computers for HEP.

- Ben Segal, CERN

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