A couple of specialists supply DJs, because you need to pull the needle forward and backwards and a standard needle wouldn’t function. But they soon became redundant; sonically the Technics are so much better.The stand-apart innovation is that they have no mechanical parts; they rely on a magnet that runs on the outside of the platter – which spins a record – making it virtually unbreakable. In the past, it was a fiddly knob, but the Technics has sliders with a green light in the middle to show normal speed, then you get plus or minus 8 per cent either side.Needles aren’t supplied with the turntable. One reason why the Technics have been so successful is that they were the first with a user-friendly speed adjuster. Because it is so stable, even with quick changes in the collage of sound, either in speed or perhaps scratching (the staple tool of hip hop DJs), it isn’t likely to jump.The turntable has a speed adjuster and an on/off button. It incorporated a turntable and mixer, and you could take it to a wedding or bar mitzvah and plug in the traffic-light-like light box, and all you needed was a sampler and speakers. There are a couple of imitation versions, which are from specialist hi-fi makers and are generally sold to bedroom DJs.
Before Technics, the mobile DJ had to make do with a very naff thing called a Disco Counsel.

On the other hand, you would be hard pushed to go into a night-club and get anything other than a Technics 1200 turntable It’s the common currency of clubland. Every single dance club has turntables and a mixer, but the mixer can come from a variety of companies (the main ones are Numark, Pioneer, Vestax). In basic terms, the turntable is the one central ingredient of DJ culture. Invented in 1979, the Technics 1200 is probably the only commercially available turntable, as well as the tool of the DJ trade. Massive data sets can take so long to load that only a little computing is done in any one window of opportunity.In fact, it was just this dilemma that prompted Mike Warren and others to build their own supercomputers. They can apply their machines widely, and to classes of problems that would only rarely get a chance on that expensive supercomputer time.For example, here at gulker , our “single-node supercomputer” is churning furiously, trying to figure out how to come up with another $700.cg gulker .

But there aren’t many supercomputers around (not at those prices!) and scientists have to queue for time on them. Distributed can crack ciphers only because its client software just knows code-breaking: running a different task would mean reinstalling tens of thousands of client software for every new job.Some problems just don’t chop up easily, and run better on the “big iron”. For one, the expensive machines tend to be more general-purpose, and have an advantage when huge volumes of data have to be loaded.Beowulf clusters tend to do best on problems that are easily broken up into independent pieces, such as particle simulations, with each machine representing a particle interacting with its neighbours. Distributed bills itself as the “Fastest Computer on Earth”, even though its hardware bill is effectively zero.To be sure, the megabucks hardware offers some advantages that the home- brew machines can’t match. It had previously been thought that such heavyweight ciphers would take hundreds of years to crack, even on fast computers.

One version of the Distributed program ran as a screen saver that kicked in, and began cracking code, when the machine was idle for more than a few minutes.You don’t normally think about a screen-saver being a powerful program, but when thousands of them act in concert, some serious computing can get done. The UCLA physics department home page mentions using other Macs in the department at nights and weekends. If the machines are on the network, they’re fair game for becoming part of the supercomputer (as long as you can persuade their regular users). UCLA’s Macs even use MacMPI, so that problems can be run on Linux or Mac or a “real” supercomputer without rewriting code.In fact earlier this year, a group called Distributed linked thousands of computers of all kinds around the world via the Internet, and cracked a 56-bit encryption code in 40 days. UCLA’s statistical mathematics department even plans to link up Apple’s new iMacs in their computer lab to make a “very pretty supercomputer”.One advantage of the design of most of these machines is that other machines can be roped in as needed for big jobs. Other Beowulf machines are called Loki (pre-Avalon), Grendel and Megalon and have various price tags, all modest for their power.The Linux OS has had a pretty phenomenal year, but an abstract on the Argonne National Laboratory website describes a machine called Chicago Pile 6 that runs under Windows NT, and Microsoft offers the “Wolfpack”, clusters of Windows NT machines that can be harnessed together for big problems.And, to round things out, a group at the UCLA Physics Department’s Plasma Simulation Group has a $28,000 parallel computer called Appleseed – eight Power Macintosh G3s – which outperforms a Cray Y-MP.