-4 In this section we look at the supercomputer situation in the UK and review the history and current use of this type of machines. The different application areas the supercomputers are used in are described and the trend to parallel systems is shown.
From the early days of computers, the United Kingdom (UK) has always played a major role in the exploitation of supercomputers. Initially, the UK built its own computers-just remember the Atlas-, then it imported them for research and academic use. Examples of this trend were the CDC 7600 at Manchester and London.
When vector supercomputers were introduced by Cray Inc. and Control Data Corp. in the late 70s, again, the UK was in the forefront of use of these machines in Europe: the first Cray machine in Europe was installed at ECMWF, the first Cyber 205 at the British Meteorological Office. The first European subsidiary of Cray Inc. was founded in the UK.
This trend, however, stopped during the late 80s. Except for ECMWF and the British Meteorological Office who were still able to exploit the top performing supercomputers like the CRAY X and Y series and the ETA-10, only smaller systems were bought by the others users.
Today, there is only one UK entry left in the first 90 entries of the TOP500, and this is owned by ECMWF, an international organisation. The first UK research site (RAL) is only at place 139.
The reasons for this relative decline are manifold, but the political priorities with regard to education and government funded research play a major role.
-2 At present, the UK has 20 supercomputers listed in the 1993 TOP500 (Table 13.3). As stated earlier, one of them, the Cray C90 at ECMWF, cannot really be counted, because it belongs to an international organisation funded by 18 European countries. Of the remaining 19 sites, seven installations support academic research, five are dedicated to classified work and three are specialised research centers. This leaves only four systems for industrial use.
The size of the machines is relatively small, only nine entries are among the
TOP200 and none in the TOP50. The percentage of massively parallel systems is relatively high: eight systems belong to this category. However, the highest number of processors is reached with 512 at Edinburgh [i]#3 in UK (TMC CM-200), followed by 128 at Grant Tensor (Intel iPSC/860)[i]#2. The remaining machines are small compared to the largest possible configurations. The total installed capacity measured in [tex2html_wrap2100] (28.7 Gflop/s without ECMWF) is less than 10%of the capacity of Japan and is only twice that of Australia (see Fig. 
and 13.2).
In summary, the UK has still the third largest installed base of supercomputers in Europe, but is less than half the size of Germany both in numbers and installed capacity and has also been overtaken by France (see Fig. 13.1).
-2 Even though the UK has recently witnessed the purchase of a number of supercomputers for academic and research use, e.g. a CRAY C90 for the British Meteorological Office and a CRAY T3D with 256 processors for the University of Edinburgh, the trend of use of supercomputers in the UK, nevertheless, seems to be unbroken. The move away from traditional supercomputers to RISC based scaleable computing is continuing, with emphasis on low cost, high performance computing.
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