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1、2022年-2023年建筑工程管理行业文档 齐鲁斌创作外文翻译原文：Progress in Computers The first stored program computers began to work around 1950. The one we built in Cambridge, the EDSAC was first used in the summer of 1949.These early experimental computers were built by people like myself with varying backgrounds. We all had
2、 extensive experience in electronic engineering and were confident that that experience would stand us in good stead. This proved true, although we had some new things to learn. The most important of these was that transients must be treated correctly; what would cause a harmless flash on the screen
3、 of a television set could lead to a serious error in a computer.As far as computing circuits were concerned, we found ourselves with an embarass de richess. For example, we could use vacuum tube diodes for gates as we did in the EDSAC or pentodes with control signals on both grids, a system widely
4、used elsewhere. This sort of choice persisted and the term families of logic came into use. Those who have worked in the computer field will remember TTL, ECL and CMOS. Of these, CMOS has now become dominant.In those early years, the IEE was still dominated by power engineering and we had to fight a
5、 number of major battles in order to get radio engineering along with the rapidly developing subject of electronics.dubbed in the IEE light current electrical engineering.properly recognised as an activity in its own right. I remember that we had some difficulty in organising a conference because th
6、e power engineers ways of doing things were not our ways. A minor source of irritation was that all IEE published papers were expected to start with a lengthy statement of earlier practice, something difficult to do when there was no earlier practiceConsolidation in the 1960s By the late 50s or earl
7、y 1960s, the heroic pioneering stage was over and the computer field was starting up in real earnest. The number of computers in the world had increased and they were much more reliable than the very early ones . To those years we can ascribe the first steps in high level languages and the first ope
8、rating systems. Experimental time-sharing was beginning, and ultimately computer graphics was to come along.Above all, transistors began to replace vacuum tubes. This change presented a formidable challenge to the engineers of the day. They had to forget what they knew about circuits and start again
9、. It can only be said that they measured up superbly well to the challenge and that the change could not have gone more smoothly. Soon it was found possible to put more than one transistor on the same bit of silicon, and this was the beginning of integrated circuits. As time went on, a sufficient le
10、vel of integration was reached for one chip to accommodate enough transistors for a small number of gates or flip flops. This led to a range of chips known as the 7400 series. The gates and flip flops were independent of one another and each had its own pins. They could be connected by off-chip wiri
11、ng to make a computer or anything else.These chips made a new kind of computer possible. It was called a minicomputer. It was something less that a mainframe, but still very powerful, and much more affordable. Instead of having one expensive mainframe for the whole organisation, a business or a univ
12、ersity was able to have a minicomputer for each major department.Before long minicomputers began to spread and become more powerful. The world was hungry for computing power and it had been very frustrating for industry not to be able to supply it on the scale required and at a reasonable cost. Mini
13、computers transformed the situation.The fall in the cost of computing did not start with the minicomputer; it had always been that way. This was what I meant when I referred in my abstract to inflation in the computer industry going the other way. As time goes on people get more for their money, not
14、 less. Research in Computer Hardware. The time that I am describing was a wonderful one for research in computer hardware. The user of the 7400 series could work at the gate and flip-flop level and yet the overall level of integration was sufficient to give a degree of reliability far above that of
15、discreet transistors. The researcher, in a university or elsewhere, could build any digital device that a fertile imagination could conjure up. In the Computer Laboratory we built the Cambridge CAP, a full-scale minicomputer with fancy capability logic. The 7400 series was still going strong in the
16、mid 1970s and was used for the Cambridge Ring, a pioneering wide-band local area network. Publication of the design study for the Ring came just before the announcement of the Ethernet. Until these two systems appeared, users had mostly been content with teletype-based local area networks. Rings nee
17、d high reliability because, as the pulses go repeatedly round the ring, they must be continually amplified and regenerated. It was the high reliability provided by the 7400 series of chips that gave us the courage needed to embark on the project for the Cambridge Ring. The RISC Movement and Its Afte
18、rmath Early computers had simple instruction sets. As time went on designers of commercially available machines added additional features which they thought would improve performance. Few comparative measurements were done and on the whole the choice of features depended upon the designers intuition
19、.In 1980, the RISC movement that was to change all this broke on the world. The movement opened with a paper by Patterson and Ditzel entitled The Case for the Reduced Instructions Set Computer.Apart from leading to a striking acronym, this title conveys little of the insights into instruction set de
20、sign which went with the RISC movement, in particular the way it facilitated pipelining, a system whereby several instructions may be in different stages of execution within the processor at the same time. Pipelining was not new, but it was new for small computers The RISC movement benefited greatly
21、 from methods which had recently become available for estimating the performance to be expected from a computer design without actually implementing it. I refer to the use of a powerful existing computer to simulate the new design. By the use of simulation, RISC advocates were able to predict with s
22、ome confidence that a good RISC design would be able to out-perform the best conventional computers using the same circuit technology. This prediction was ultimately born out in practice.Simulation made rapid progress and soon came into universal use by computer designers. In consequence, computer d
23、esign has become more of a science and less of an art. Today, designers expect to have a roomful of, computers available to do their simulations, not just one. They refer to such a roomful by the attractive name of computer farm. The x86 Instruction Set Little is now heard of pre-RISC instruction se
24、ts with one major exception, namely that of the Intel 8086 and its progeny, collectively referred to as x86. This has become the dominant instruction set and the RISC instruction sets that originally had a considerable measure of success are having to put up a hard fight for survival.This dominance
25、of x86 disappoints people like myself who come from the research wings.both academic and industrial.of the computer field. No doubt, business considerations have a lot to do with the survival of x86, but there are other reasons as well. However much we research oriented people would like to think ot
26、herwise. high level languages have not yet eliminated the use of machine code altogether. We need to keep reminding ourselves that there is much to be said for strict binary compatibility with previous usage when that can be attained. Nevertheless, things might have been different if Intels major at
27、tempt to produce a good RISC chip had been more successful. I am referring to the i860 (not the i960, which was something different). In many ways the i860 was an excellent chip, but its software interface did not fit it to be used in a workstation. There is an interesting sting in the tail of this
28、apparently easy triumph of the x86 instruction set. It proved impossible to match the steadily increasing speed of RISC processors by direct implementation of the x86 instruction set as had been done in the past. Instead, designers took a leaf out of the RISC book; although it is not obvious, on the
29、 surface, a modern x86 processor chip contains hidden within it a RISC-style processor with its own internal RISC coding. The incoming x86 code is, after suitable massaging, converted into this internal code and handed over to the RISC processor where the critical execution is performed. In this sum
30、ming up of the RISC movement, I rely heavily on the latest edition of Hennessy and Pattersons books on computer design as my supporting authority; see in particular Computer Architecture, third edition, 2003, pp 146, 151-4, 157-8. The IA-64 instruction set. Some time ago, Intel and Hewlett-Packard i
31、ntroduced the IA-64 instruction set. This was primarily intended to meet a generally recognised need for a 64 bit address space. In this, it followed the lead of the designers of the MIPS R4000 and Alpha. However one would have thought that Intel would have stressed compatibility with the x86; the p
32、uzzle is that they did the exact opposite. Moreover, built into the design of IA-64 is a feature known as predication which makes it incompatible in a major way with all other instruction sets. In particular, it needs 6 extra bits with each instruction. This upsets the traditional balance between in
33、struction word length and information content, and it changes significantly the brief of the compiler writer. In spite of having an entirely new instruction set, Intel made the puzzling claim that chips based on IA-64 would be compatible with earlier x86 chips. It was hard to see exactly what was me
34、ant.Chips for the latest IA-64 processor, namely, the Itanium, appear to have special hardware for compatibility. Even so, x86 code runs very slowly.Because of the above complications, implementation of IA-64 requires a larger chip than is required for more conventional instruction sets. This in tur
35、n implies a higher cost. Such at any rate, is the received wisdom, and, as a general principle, it was repeated as such by Gordon Moore when he visited Cambridge recently to open the Betty and Gordon Moore Library. I have, however, heard it said that the matter appears differently from within Intel.
36、 This I do not understand. But I am very ready to admit that I am completely out of my depth as regards the economics of the semiconductor industry. AMD have defined a 64 bit instruction set that is more compatible with x86 and they appear to be making headway with it. The chip is not a particularly
37、 large one. Some people think that this is what Intel should have done. Since the lecture was delivered, Intel have announced that they will market a range of chips essentially compatible with those offered by AMD. The Relentless Drive towards Smaller Transistors The scale of integration continued t
38、o increase. This was achieved by shrinking the original transistors so that more could be put on a chip. Moreover, the laws of physics were on the side of the manufacturers. The transistors also got faster, simply by getting smaller. It was therefore possible to have, at the same time, both high den
39、sity and high speed. There was a further advantage. Chips are made on discs of silicon, known as wafers. Each wafer has on it a large number of individual chips, which are processed together and later separated. Since shrinkage makes it possible to get more chips on a wafer, the cost per chip goes d
40、own. Falling unit cost was important to the industry because, if the latest chips are cheaper to make as well as faster, there is no reason to go on offering the old ones, at least not indefinitely. There can thus be one product for the entire market. However, detailed cost calculations showed that,
41、 in order to maintain this advantage as shrinkage proceeded beyond a certain point, it would be necessary to move to larger wafers. The increase in the size of wafers was no small matter. Originally, wafers were one or two inches in diameter, and by 2000 they were as much as twelve inches. At first,
42、 it puzzled me that, when shrinkage presented so many other problems, the industry should make things harder for itself by going to larger wafers. I now see that reducing unit cost was just as important to the industry as increasing the number of transistors on a chip, and that this justified the ad
43、ditional investment in foundries and the increased risk. The degree of integration is measured by the feature size, which, for a given technology, is best defined as the half the distance between wires in the densest chips made in that technology. At the present time, production of 90 nm chips is st
44、ill building upSuspension of Law In March 1997, Gordon Moore was a guest speaker at the celebrations of the centenary of the discovery of the electron held at the Cavendish Laboratory. It was during the course of his lecture that I first heard the fact that you can have silicon chips that are both f
45、ast and low in cost described as a violation of Murphys law.or Sods law as it is usually called in the UK. Moore said that experience in other fields would lead you to expect to have to choose between speed and cost, or to compromise between them. In fact, in the case of silicon chips, it is possibl
46、e to have both.In a reference book available on the web, Murphy is identified as an engineer working on human acceleration tests for the US Air Force in 1949. However, we were perfectly familiar with the law in my student days, when we called it by a much more prosaic name than either of those menti
47、oned above, namely, the Law of General Cussedness. We even had a mock examination question in which the law featured. It was the type of question in which the first part asks for a definition of some law or principle and the second part contains a problem to be solved with the aid of it. In our case
48、 the first part was to define the Law of General Cussedness and the second was the problem;A cyclist sets out on a circular cycling tour. Derive an equation giving the direction of the wind at any time. The single-chip computer At each shrinkage the number of chips was reduced and there were fewer w
49、ires going from one chip to another. This led to an additional increment in overall speed, since the transmission of signals from one chip to another takes a long time. Eventually, shrinkage proceeded to the point at which the whole processor except for the caches could be put on one chip. This enabled a workstation to be built that out-performed the fastest minicomputer of the day, and the result was to kill the minicomputer stone dead. As we all know, this had severe consequence