1、3外文资料原文 Progress in Computers Prestige Lecture delivered to IEE, Cambridge, on 5 February 2004 Maurice Wilkes Computer Laboratory University of Cambridge 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
2、 early experimental computers were built by people like myself with varying backgrounds. We all had 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 t
3、hese was that transients must be treated correctly； what would cause a harmless flash on the screen 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 diod
4、es for gates as we did in the EDSAC or pentodes with control signals on both grids, a system widely 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 d
5、ominant. In those early years, the IEE was still dominated by power engineering and we had to fight a 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.properlyrecognised as an act
6、ivity in its own right. I remember that we had some difficulty in organising a conference because the 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
7、difficult to do when there was no earlier practice Consolidation in the 1960s By the late 50s or early 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
8、 early ones . To those years we can ascribe the first steps in high level languages and the first operating 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 c
9、hallenge to the engineers of the day. They had to forget what they knew about circuits and start again. 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 sa
10、me bit of silicon, and this was the beginning of integrated circuits. As time went on, a sufficient level 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 flo
11、ps were independent of one another and each had its own pins. They could be connected by off-chip wiring 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
12、 affordable. Instead of having one expensive mainframe for the whole organisation, a business or a university 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 f
13、rustrating for industry not to be able to supply it on the scale required and at a reasonable cost. Minicomputers 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 inf
14、lation in the computer industry going the other way. As time goes on people get more for their money, not 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 a
15、nd yet the overall level of integration was sufficient to give a degree of reliability far above that of 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 C
16、AP, a full-scale minicomputer with fancy capability logic. The 7400 series was still going strong in the 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 the
17、se two systems appeared, users had mostly been content with teletype-based local area networks. Rings need 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 g
18、ave us the courage needed to embark on the project for the Cambridge Ring. The RISC Movement and Its Aftermath 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 compara
19、tive measurements were done and on the whole the choice of features depended upon the designers intuition. 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.
