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FOCUS: HARDWAREInterview with Professor Ken BowlerProf. Ken Bowler was one of EPCC’s original founders, the so-called Gang of Four, alongwith Richard Kenway, Stuart Pawley and David Wallace. Gavin J. Pringle spoke to Prof.Bowler prior to his retiral this summer. Here is a paraphrased version of that meeting.Ken and ChrisBowler.What was the first parallel machine youwere involved with?That was the ICL DAP, in 1980,housed at Queen Mary’s College(QMC) in London. Stuart Pawley was reallythe pioneer, using it for molecular dynamicssimulations.transputers as the processing elements. The original machinewasn’t a serious compute engine for QCD problems, asit didn’t have the computational oomph. But it was aninteresting learning experience for us, dealing with a MIMDarchitecture, compared with the old DAP SIMD. We did lookat a few particle physics calculations, but they were really toycalculations, rather than QCD in anger.It was that time we realised that our problems were suitablefor that kind of architecture. We got together with Stuart anddid an initial study with the QMC machine, which was aninteresting exercise in itself, because we had to use an acousticmodem to link up to the machine in QMC, and we got ourresults back through the post!These were interesting results, and we spent some timetalking to Stuart Reddaway, from ICL, who was an architectof the DAP. We formed a good relationship with ICL whichresulted in us getting one machine here in ‘82, and a secondDAP in ‘83. The machines were hosted by EdinburghUniversity Computing Services (EUCS). The then deputydirector of the EUCS, Andrew McKendrick, and Mike Brown,the DAP’s system manager, helped us a lot in those early days.The follow up to the Meiko was a big transputer machinecalled the Edinburgh Concurrent Supercomputer and it wasaround then that EPCC was established. A range of differentapplications were ported to that machine.It was a very big transputer-based computing surface, with400 T800 processors; it was certainly a serious machine.That was an interesting exercise because it was essentiallythe start of UKQCD collaboration. A groupContinued opposite.So the DAP, for us, was very successful. It enabled us tocompete with people elsewhere who had time on big,expensive vector machines like the Cray and the Cyber 205,whereas the DAP was relatively modest, but, as it was aparallel architecture, we were able to compete effectively.The DAP was an adaptation of a memory module of the2900 Series ICL mainframe computers, which were greatbig monster machines. It had processing elements wiredinto these memory modules. In a sense, it was a back-endprocessor, where the code ran on the ICL mainframe hostmachine, and the DAP subroutines were executed on thisrather bizarre piece of ironmongery.After the ICL DAP, you moved to a Meiko platform.This also predates EPCC. It was 1986 when we got ourfirst Meiko machine; it was a very small Meiko, calledthe Computing Surface, and it had the old T414 integerThe Meiko Computing Surface.ICL DAP.10
FOCUS: HARDWAREof us from across the UK working in lattice gauge theoryand lattice QCD decided that the only way forward was bycollaboration, and put together a joint proposal for a bigmachine to do lattice QCD.Cray T3E (right)and T3D (below).We were awarded a grant from the Nuclear Physics Boardof the Science Research Council, which funded the purchaseof the Meiko i860 box, which, by the standards of the time,was quite a powerful machine. It had a peak performance of5 gigaflops – a big deal in those days!That was the first instance of a UK-wide national service, but it wasonly for one consortium?It was for one consortium, but then it was extended. We gotmore memory and a second smaller machine by collaboratingwith the Car-Parinello Consortium, led by Dominic Tildesleyfrom Southampton. This collaboration really launchedUKQCD on to the world stage and we got a lot of goodphysics out of that machine from 1990 to 1995, or so. I canstill remember coming in at Christmas and New Year andputting in Exabyte tapes in the Meiko machine to save ourdata. It was very much a string-and-sealing-wax kind ofoperation.So Edinburgh Parallel Computing Centre emerged as a support centrefor these consortia. And then we got the Thinking Machines’ CM-200system.Yes, the CM-200 was used by some people in UKQCD forsome of our calculations, but we didn’t have exclusive useof it, nor exclusive ownership, so it was a relatively smallcontribution to the overall computing needs that we had.They also had this wonderful data store that looked like acocktail bar: the Data Vault!Yes, we had it in the EPCC staffroom. It was huge and could hold10 GBytes. We now carry around 60 gigs in an iPod!It is absolutely staggering!Then, after the CM-200, came the Cray T3D.The T3D was funded as a national computing resource andvarious consortia bid for time on that, including UKQCD. Wemade very good use of the T3D, as we had a pretty significantallocation of time on it; however, it was a change of modelfor us. The Meiko had been very much our own baby: an inhousemachine, whilst the T3D was run as a shared resourcewith a professional service. But following on from that, weconverted back to the old model, applying to PPARC fora large-scale QCD machine. A procurement exercise wascarried out and the outcome was the Cray T3E.Again, it was a shared facility among three PPARC consortia:Virgo, ourselves and the MHD Consortium. The T3E was ourmainstay for two or three years or so.There was something of a hiatus for us after the demise of theT3E. The demands on QCD were going up dramatically andwe had to be more ambitious and think on a bigger scale, andthat was the thinking that lead to the QCDOC project.We put together a bid under the JIF heading (JointInfrastructure Fund) without too much hope of success, as JIFdidn’t typically fund supercomputers. The bid was originallybased on a machine called QCDSP, designed and built inColumbia University (CU), by Norman Christ’s group. Thathad been a successful machine and a big version of it hadbeen built and installed in Brookhaven. It was based on TexasInstruments Digital Signal Processing chips with some custominterconnect.But in the meantime, Norman’s ideas became more ambitiousand he started talking with IBM. There was now an upgradedproject based around QCDOC which involved IBM andwe were funded, somewhat to our surprise. After the openThinking Machine’sCM-200 and the DataVault.Continued over.11
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