The Central Computer and Telecommunications Agency (CCTA), formerly the Central Computer Agency (CCA), was a UK government agency providing computer and telecoms support to government departments.
History
Formation
Archived records
CCTA records are held by The National Archives.
In 1957, the UK government formed the Central Computer Agency (CCA) Technical Support Unit (TSU) within HM Treasury to evaluate and advise on computers, initially based around engineers from the telecommunications service. As this unit evolved, it morphed into the Central Computer and Telecommunications Agency, which also had responsibilities for procurement of United Kingdom Government technological equipment, and later, that centrally funded for University and Research Council systems.
Technical services
Note that nearly all names and authors, quoted or referenced in this section, were CCTA engineers or scientists.
The first external technical publication was in 1960 by J. W. Freebody and J. W. Heron, as "Some engineering factors of importance in relation to the reliability of government A.D.P. systems". Nearly 30 computer systems had been installed at that time. The conclusion was that reliability was the most important single factor, identifying areas and activities that required investigation by the new organisation. A later career review confirmed that John Freebody was promoted to Staff Engineer and set the task of founding the Technical Support Unit.
In 1965 responsibility for TSU was transferred from HM Treasury to the Ministry of Technology. At that time telecommunications engineering staff comprised 8 dealing with Systems Evaluations, 6 with Peripheral Equipment and 10 in the areas of Accommodation, Testing, and Maintenance. Details of names, grades, qualifications, salary and relevant experience can be found in Hansard Volume 717: debated on Tuesday 27 July 1965.
Technical services reliability and acceptance trials
Procurement contracts included guaranteed service levels where, at least in the early days, was monitored by TSU engineers, to whom all fault incident occurrences and system availability levels were submitted on a monthly basis. The contracts also included requirements to run on-site and sometimes predelivery acceptance trials of a specified format, designed and supervised by engineering staff.
The acceptance tests comprised a series of demonstrations to verify that everything had been delivered and appeared to function, followed by stress testing of up to 40 hours, over a few days, depending on system size. For the latter, engineering test programs were included and available user applications. Then, the criterion of success was to achieve a given level of uptime. In 1968, new procedures were introduced, particularly involving stress testing, where each main tests were aimed to run for 15 minutes, with criteria that, besides a maximum time limit, each test was required to run failure free six times in succession.
During this period, on invitation, five CCTA engineers presented papers on acceptance testing at the Institution of Electrical Engineers.
At this stage, concern was raised regarding how to test computers with the new Multiprogramming Operating Systems. The problem was solved by Roy Longbottom who, at various promotion levels between 1968 and 1982, was responsible for designing and supervising acceptance trials of the larger scientific systems. He produced 17 programs, written in the FORTRAN programming language, 5 for CPUs, 4 for disk drives, 3 for magnetic tape units and others for printers, card and paper tape punchers and readers. Program code listings are included in the book *Computer System Reliability* (Appendix 1).
By 1972, 800 acceptance tests of computers systems and enhancements had been carried out including 500 for complete systems, reported in The Post Office Electrical Engineers' Journal. The latter tests included 100 using the new procedures from 11 different contractors. The first candidate was an IBM 360 Model 65 at University College London in 1971, then in 1972 by trials on all mainframes, minicomputers and supercomputers covered by CCTA contracts. Later that year, top end systems tested were the $5 million scalar supercomputers CDC 7600 at University of London Computer Centre and IBM 360/195 at UK Meteorological Office. Not included in these 100, but significant, 1973 trials included the Atlas (computer) at Cambridge University, a latter day version of the 1962 UK supercomputer. During the 100 trials, 23 systems failed to meet the specified criteria, at the first attempt.
By 1979 more than 1600 acceptance tests of computers systems and enhancements had been carried out. For the latest 400 system tests, carried out under the new procedures, 14% were recorded as failures and 24% as having a conditional pass. Up to three attempts were allowed with none being completely rejected, albeit some accepted with penalty conditions. See Chapter 10 in the Longbottom book.
Detailed analysis of fault returns, hands on observations during acceptance trials and system appraisal activities lead to a deeper understanding of reliability issues, published in a 1972 Radio and Electronic Engineer Journal, titled "Analysis of Computer System Reliability and Maintainability", with probability considerations. Later, came a conference paper "Reliability of Computer Systems" (Archive) and the Roy Longbottom book that particularly acknowledges input provided by Ian Thomson on computer system maintainability and Trevor Jones on environmental aspects.
Trials in 1979 included the first Cray 1 vector supercomputer to be delivered to the UK at Atomic Weapons Research Establishment and, by 1982, the CDC Cyber 205 for UK Meteorological Office, where total system costs could be $10 million. Both these systems had pre-delivery trials in the USA. For these, Roy Longbottom converted the scalar CPU programs to fully exploit capabilities of the new vector processors. Results of the converted Vector Whetstone (benchmark) were included in the paper "Performance of Multi-User Supercomputing Facilities" presented in the 1989 Fourth International Conference on Supercomputing, Santa Clara.
Details were also included in the June 1990 Advanced Computing Seminar at Natural Environment Research Council Wallingford. This led to Council for the Central Laboratory of the Research Councils Distributed Computing Support collecting results from running "on a variety of machines, including vector supercomputers, minisupers, super-workstations and workstations, together with that obtained on a number of vector CPUs and on single nodes of various MPP machines". More than 200 results are included, up to 2006, in the report available on the Wayback Machine Archive in entries to at least the year 2007 section.
For the systems identified as supercomputers, there were nine acceptance testing sessions, two of which were failures, one due to excessive CPU problems and the other due to design issues on the I/O subsystem. Both of these were induced by the CCTA stress testing programs.
Technical services system appraisal
During the early days there were considerations of future technology, including telecommunications in the 1970 book "Data transmission – the future: the development of data transmission to meet future users' needs" found in National Library of Australia catalog 169638. But the main emphasis was appraisal of the latest computer system hardware and software. Initially, this involved collecting information on all appropriate new products, followed by more detailed investigation when being considered for a new project. This included a tour of the production factory and discussions with higher level engineering, design and quality control staff.
The National Archives CCTA records include technical appraisal reports (at the time of writing), up to 1986 (search for quoted reports). The first in a finally standard format was "System Summary Notes" (range 5000 to 6999), starting in 1967, with such as early IBM 360 mainframes and Digital Equipment Corporation PDP 8 minicomputer, up to the last issue in 1980. These are based on standard forms with numerous entries. Other reports identified in the Archives are "Technical Notes" between 1975 and 1986, "Internal Technical Memoranda" 1973 to 1986 and "Technical Memoranda"1975 to 1986". The number of reports cannot be easily determined from the provided data..
Computer system performance
Before cross the board standard benchmarks became available, average speed rating of computers was based on calculations for a mix of instructions with the result given in Kilo Instructions Per Second (KIPS). The most famous was the Gibson Mix for scientific computing. This was included in CCTA calculations that included those for an ADP Mix and a Process Control Mix, in CCTA Technical Note 3806 Issue 5 with 212 sets of results from 18 manufacturers, pre-1960 to 1971. In 1977, later results were included in CCTA Technical Memorandum 1163, (both via ). All those results are also available in a 2017 PDF file.
In 1972, Harold Curnow wrote the Whetstone Benchmark in the FORTRAN programming Language, based on the work of Brian Wichmann of the National Physical Laboratory. This executes 8 test functions, 5 of which involve floating point calculations that dominate running time. Overall performance was calculated in thousands of Whetstone instructions per second (KWIPS). The program became the first general purpose benchmark that set industry standards of computer system performance. Enhancements by Roy Longbottom provided self timing arrangements and calibration to run for a predetermined time on present and future systems, also performance of each of the 8 tests. The calibrated time was mainly for 10 seconds and is still applicable after 50 years.
In 1978, Roy Longbottom, who inherited the role of design authority of the benchmark, also produced a version to exploit supercomputer processing hardware, covered in reports "Performance of Multi-User Supercomputing Facilities" and "Whither Whetstone? The synthetic benchmark after 15 years" in book.
Original Whetstone Benchmark results are in 1985 CCTA Technical Memorandum 1182, (via Archive). where overall speed is shown as MWIPS (Millions). This contains more than 1000 results for 244 computers from 32 manufacturers.
On achieving 1 MWIPS, the Digital Equipment Corporation VAX-11/780 minicomputer became accepted as the first commercially available 32-bit computer to demonstrate 1 MIPS (Millions of Instructions Per Second), CERN, not really appropriate for a benchmark dependent on floating point speed. This had an impact on the Dhrystone Benchmark, the second accepted general purpose computer performance measurement program, with no floating point calculations. This produced a result of 1757 Dhrystones Per Second on the VAX 11/780, leading to a revised measurement of 1 DMIPS, (AKA Vax MIPS), by dividing the original result by 1757.
The Whetstone Benchmark also had high visibility concerning floating point performance of Intel CPUs and PCs, starting with the 1980 Intel 8087 coprocessor. This was reported in the 1986 Intel Application Report "High Speed Numerics with the 80186/80188 and 8087". The latter includes hardware functions for exponential, logarithmic or trigonometric calculations, as used in two of the eight Whetstone Benchmark tests, where these can dominate running time. Only two other benchmarks were included in the Intel procedures, showing huge gains over the earlier software based routines on all three programs.
Later tests, by a SSEMC Laboratory, evaluated Intel 80486 compatible CPU chips using their Universal Chip Analyzer.