Supercomputing returned to the Atlas Centre in 1987 following a report published in 1985 of a joint Working Party of the Advisory Board for Research Councils, the University Grants Committee and the Computer Board, chaired by Professor A J Forty, to investigate the need and recommend provision for advanced research computing in the UK. The Working Party's recommendations (in what was usually referred to as the 'Forty Report') were wide ranging and included a number of enhancements to existing facilities, the major one being 'the purchase of a Cray X-MP/48 to be installed in 1987 at the Atlas Centre of RAL for the Research Councils and their academic communities'.
The machine arrived at Atlas at the end of 1986 and was brought into service a few weeks later. It had a shared memory vector-parallel architecture, and its initial configuration was four processors (8.5 nsec cycle time, peak performance 235 MFlops per processor), 8 Mwords (64 MB) of memory (later increased to 16 Mwords), a 32 Mwords Solid State Device and 14.4 GB of disk. A 256 Mword (2 GB) Solid State Device was added in 1993. The Cray was front-ended by the Atlas Centre's IBM 3081K, and VAX/VMS and Unix front ends were added later as funds became available. User access was via the Joint Academic Network (JANET).
Users were authorised to use the Cray X-MP by the normal peer review processes of the Research Councils that supported their specific disciplines. Altogether around 200 projects became authorised. The largest number of users and projects came via the Science Board of SERC, particularly in physics, chemistry and protein crystallography. The major engineering applications were in structural analysis and computational fluid dynamics, while biological science work included drug design and epidemiology. The largest individual projects in terms of computing resources came from the Natural Environment Research Council to model the motions of oceans and the atmosphere. A report issued after the first year of operation noted that there had been 151 known journal publications arising from science projects conducted on the Cray.
By the early 1990s the machine was saturated and the Research Councils' Supercomputing Management Committee (SMC) authorised its replacement by a Cray Y-MP with about three times the power. The Y-MP, which came into service in October 1992, had the same basic architecture as the X-MP, although it had 32 bit address registers instead of 24 to allow larger memory configurations. It also used the same operating systems, so the transition for users was straightforward. The Y-MP had 8 processors (6nsec cycle time, peak performance 333 Mflops per processor) 128 Mwords (1GB) of shared memory and 100 GB of disk.
In 1994 much of the focus of the Research Councils' national supercomputing facilities moved to the University of Edinburgh with the installation of a Cray T3D, a distributed memory - distributed processor system with 256 processors, which was considerably more powerful than the Atlas Centre's Cray Y-MP.
The Atlas Cray Y-MP would continue to serve the Research Council user communities until 1996, when it was replaced by a more powerful 32-processor shared memory Cray J90 system.
Further details on the Atlas Centre's supercomputing services and how they were used can be found in the Literature accessible from this page and also from Cray User Meetings and Applications sections. To provide a wider perspective, this page includes links to two reports of Town Meetings on Supercomputing, in 1989 and 1992, and one on a National Centres Open Meeting which provide useful snapshots of the prevailing situations in UK academic high performance computing more generally, together with concerns and ideas on future needs.
