Supercomputer

“ Since this term first entered the Jargon File in 1990, the minicomputer has effectively vanished, the mainframe sector is in deep and apparently terminal decline (with IBM but a shadow of its former self) , and even the supercomputer business has contracted into a smaller niche. It's networked killer micros as far as the eye can see. ”

“ WHY DOESN'T SOMEBODY BUY THIS WOMAN HER AMIGA?! It's not like she's asking for a Cray X-MP supercomputer mainframe; an Amiga's a sweet little cookie-box thing. We're losing zillions in organized fraud; prosecuting and defending a single hacker case in court can cost a hundred grand easy. How come nobody can come up with four lousy grand so this woman can do her job? For a hundred grand we could buy every computer cop in America an Amiga. ”

“ It should come as no surprise, then, that most CGCMs prominently feature systems of nonlinear equations, and that one of the primary challenges of working with CGCMs revolves around how to handle these non-linearities. While the use of supercomputers to simulate the behavior of the global climate is absolutely essential if we’re to do any useful work with CGCMs, fundamental features of digital computers give rise to a set of serious challenges for researchers seeking to simulate the behavior of the global climate. ”

“ The term carries the connotation of a machine designed for batch rather than interactive use, though possibly with an interactive timesharing operating system retrofitted onto it; it is especially used of machines built by IBM, Unisys, and the other great {dinosaur}s surviving from computing's {Stone Age}.
It is common wisdom among hackers that the mainframe architectural tradition is essentially dead (outside of the tiny market for {number-crunching} supercomputers (see {cray}) ) , having been swamped by the recent huge advances in IC technology and low-cost personal computing. ”

“ Far better for intelligence agencies to work on more powerful computers and truly effective software for cracking codes. Breakthroughs might not come immediately, but would sooner or later, and the civilian sector might ultimately benefit when the technology finally did reach the world at large. Advanced supercomputers, for example, could be used for weather forecasting, or for graphics and design—the same wizardry that had helped make possible the Visible Human Project described in the last chapter. ”

“ This usage is common in people who hack supercomputers and heavy-duty number-crunching, rare to unknown elsewhere (if you say "codes" to hackers outside scientific computing, their first association is likely to be "and cyphers") . ”

“ In one sense, such devices are computationally universal. That is, certain mathematical technicalities aside, they can carry out any arbitrary Turing machine computation and, accepting the Church-Turing Thesis, can also carry out any algorithmic process. Thus, if any machine can be intelligent one need look no further than to a general-purpose computer, for there is some program which will cause the machine to display the desired intelligent behavior. This is so even if one insists that brains, for example, are machines, but are not at all like digital computers. ”

“ In medium and large systems the use of small computers for coupling input and output devices to the main computer offers a number of attractive advantages, especially now that mass production and competition have brought the prices down so low that a large amount of hardware nearly ideal for the purpose is available at a bargain. Some advantages: (1) The small machine can control data acquisition, accumulating blocks of data while the large machine is doing background calculations, interrupting those calculations only occasionally to transfer raw or partially processed data. ”

“ Most remote computers operate on a multiprogramming basis, hence prompt interrupts are not available. The waiting time for attention might typically be several tenths of a second, therefore the computer in the physics laboratory should be fairly powerful in order to handle the preliminary processing and buffering. With such a computer at work the necessity for fairly rapid access to the large remote machine may entirely disappear, or else the experimenter may be able to store partly processed data on magnetic tape for subsequent further reduction off-line at the computing center. ”

“ It can also “learn” to play a mediocre game of chess.
If we investigate the workings of a digital computer, we find much to remind us of the human brain. First is the obvious similarity of on-off, yes-no operation. This implies a power source, usually electrical, and a number of two-position switches. The over-all configuration of the classic computer resembles, in principal if not physical appearance, that of the human brain and its accessories.
As we have learned, the electronic computer has an input section, a control, an arithmetic (or logic) section, a memory, and an output. ”

“ In a small but increasing number of cases a computer is seen dedicated entirely to a "process-control" application such as the automatic adjustment of the shim coils of a variable-energy cyclotron or the control of data acquisition in a nuclear-scattering experiment, adjustments such as changing the angle of observation being made essentially under direct automatic control of the computer. The smallest on-line systems use the smallest commercially available computers; the largest use computers bigger than those which until recently served most computing centers. ”

“ Since logical users within a physical user are not memory-protected against each other, they may communicate rapidly, at full machine speed. Communication between different physical users is also possible, via real or simulated I/O devices. While this system by no means guarantees execution time to any but the highest priority user, it is adequate in a single-experiment environment. The assumption is that the experimenter, who has actual control of the computer at all times, loads his logical users in the order in which he requires their priorities. ”

“ The physicists were not anxious to undertake what was expected to be a substantial systems program development task for the coupled system, being unconvinced that the result would be worth the effort. While they still wish to increase the computing power available to them on-site, they have elected to achieve that end by expanding high-speed core storage on their machines, at least until true time-sharing becomes available at the central computing facility. ”

“ At the same time, a quantum computer with a subset of very fast control mechanisms is limited by the slowest essential gate process, as QuDOS can only operate as fast as the 2-qubit entangling gate in Layer 1 permits. For large-scale quantum computing, the speed of logical, error-corrected operations is the crucial figure of merit. Figure 17 also highlights the fact that different control operations in the computer occur on substantially different time scales; achieving synchronization of these processes is an important function for a quantum-computer architecture. ”

“ Although the physics is well understood, developing devices that compute with quantum mechanics is technologically daunting. While experiments to date manipulate only a handful of quantum bits [1] , we consider what effort is required to build a large-scale quantum computer. This objective demands more than a cursory estimate of the number of qubits and gates required for a given algorithm. One must consider the faulty quantum hardware, with errors caused by both the environment and deliberate control operations; the classical processing required when error correction is invoked ”

“ Then I asked myself, if it isn't suited to computers, what is it good for? It's no good for computers because it doesn't discharge completely. Or rather, it does and it doesn't. Its structure is altered by the saturation charge and subsequent discharge in the computation processes. But random and not-so-random charges build up again for some reason, and interfere with computations after the machine has been used a few times. I puzzled over this. It was too much like true memory. I think what we have in this computer setup is more like a non-living thinking brain than a simple computer. ”

“ However, we should question the wisdom of assembling a system based on a large machine unless a substantial amount of numerical calculating is anticipated, because the essential advantage of the large computer—the advantage that costs so much—is its capacity for rapidly executing highly accurate floating-point arithmetical operations. ”

“ Although the use of a small data-acquisition and experiment-control computer on-line to a remote computing center machine is not uncommon in high-energy particle physics applications, we know of few such systems presently operating in low-energy nuclear physics. ”

“ In ordering a new computer powerful enough to handle most of the nuclear physics laboratory's data analysis and theoretical computing tasks, cost ruled out the acquisition of a pair of program-compatible computers. ”

“ On left is an array of 16 analog computers; at right is a large digital data-processing system.
The facility can perform scientific and business tasks simultaneously.
The dictionary also gives us a good clue to the digital computer: “Digital.—Of the fingers or digits.” A digital machine deals in digits, or discrete units, in its calculations. For instance, if we ask it to multiply 2 times 2, it answers that the product is exactly 4. A slide rule, which we have said is an analog device, might yield an answer of 3.98 or 4.02, depending on the quality of its workmanship and our eyesight. ”

“ Since the ultimate criterion is research output, the role assigned to a computer system must depend on the nature of the work being planned. In some cases where a very specific use is intended, for example, in the case of a process-control application such as the Argonne plate scanner or an accelerator controller, the conditions are simple enough to make economic judgment relatively easy to apply. In the case encountered in setting up an accelerator laboratory where a wide variety of experiments is to be performed, conditions are much more complex. ”

“ In many cases, especially where typical standard operations are involved, it is preferable to use external devices to handle preliminary selection and sorting of events, rather than to ask the computer to do the entire job. For example, particle identification by use of signals from two counters involves one or two multiplications and additions, which can be carried out almost instantly by a fairly simple external analog device, whereas a small computer would likely require at least 500 μsec for the job, assuming calculation, and perhaps 40 μsec, assuming table look-up. ”

“ Term used to refer to a well-known effect whereby function in a computing system family is migrated out to special-purpose peripheral hardware for speed, then the peripheral evolves toward more computing power as it does its job, then somebody notices that it is inefficient to support two asymmetrical processors in the architecture and folds the function back into the main CPU, at which point the cycle begins again. Several iterations of this cycle have been observed in graphics-processor design, and at least one or two in communications and floating-point processors. ”

“ Common figures of merit for evaluating quantumcomputing technology are gate fidelity, operation time, and qubit coherence time. This investigation goes further to show how connectivity and classical control performance are also crucial. Designing a quantum computer requires viewing the system as a whole, such that tradeoffs and compatibility between component choices must be addressed. A holistic picture is equally important for comparing different quantum-computing technologies, such as ion traps or superconducting circuits. ”

“ Proper interconnection of sufficient on-off switches makes possible the 87most flexible of all computers—man’s brain. By the same token, man-made computers of the digital type can do a wider variety of jobs than can the analog which seemingly is more sophisticated.
A second great virtue of the digital machine is its accuracy. Even a trial machine of Babbage had a 5-place accuracy. This is an error of only one part in ten thousand, achievable in the analog at great expense. This was of course only a preliminary model, and the English inventor planned 20-place accuracy in his dream computer. ”

“ Even though ordinary computing machines do not, for example, reproduce themselves, they can be programmed to simulate the behavior of machines that do in fact reproduce. From this point of view, the concept of machines which posses the power to construct other machines and to replicate themselves can be represented to any degree of detail in the computation of an ordinary general-purpose computing machine which cannot itself reproduce. ”

“ These allow sequential depositing of digital data from external devices directly into blocks of computer memory without intervention of the central processor (direct memory access, DMA) . Such input may require only one computer cycle per [Pg 8] word, that being the next cycle after the one during which the interrupt signal arrives. This is the fastest means of getting data into memory, but it requires more external hardware and more complex interfacing than input through an accumulator of the central processor. Most data-acquisition machines provide both possibilities. ”