In a demand paging system, M is the time to access memory, F is the average time to service a page fault. P is the probability of page fault. Then the effective access time is : ?->(Show Answer!)

1. In a demand paging system, M is the time to access memory, F is the average time to service a page fault. P is the probability of page fault. Then the effective access time is :

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MCQ-> Analyze the following passage and provide appreciate answers for the questions that follow. Ideas involving the theory probability play a decisive part in modern physics. Yet we will still lack a satisfactory, consistence definition of probability; or, what amounts to much the same, we still lack a satisfactory axiomatic system for the calculus of probability. The relations between probability and experience are also still in need of clarification. In investigating this problem we shall discover what will at first seem an almost insuperable objection to my methodological views. For although probability statements play such a vitally important role in empirical science, they turn out to be in principle impervious to strict falsification. Yet this very stumbling block will become a touchstone upon which to test my theory, in order to find out what it is worth. Thus, we are confronted with two tasks. The first is to provide new foundations for the calculus of probability. This I shall try to do by developing the theory of probability as a frequency theory, along the lines followed by Richard von Mises, But without the use of what he calls the ‘axiom of convergence’ (or ‘limit axiom’) and with a somewhat weakened ‘axiom of randomness’ The second task is to elucidate the relations between probability and experience. This means solving what I call the problem of decidability statements. My hope is that the investigations will help to relieve the present unsatisfactory situation in which physicists make much use of probabilities without being able to say, consistently, what they mean by ‘probability’.The statement, “The relations between probability and experience are still in need of clarification” implies that:
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MCQ-> In a modern computer, electronic and magnetic storage technologies play complementary roles. Electronic memory chips are fast but volatile (their contents are lost when the computer is unplugged). Magnetic tapes and hard disks are slower, but have the advantage that they are non-volatile, so that they can be used to store software and documents even when the power is off.In laboratories around the world, however, researchers are hoping to achieve the best of both worlds. They are trying to build magnetic memory chips that could be used in place of today’s electronics. These magnetic memories would be nonvolatile; but they would also he faster, would consume less power, and would be able to stand up to hazardous environments more easily. Such chips would have obvious applications in storage cards for digital cameras and music- players; they would enable handheld and laptop computers to boot up more quickly and to operate for longer; they would allow desktop computers to run faster; they would doubtless have military and space-faring advantages too. But although the theory behind them looks solid, there are tricky practical problems and need to be overcome.Two different approaches, based on different magnetic phenomena, are being pursued. The first, being investigated by Gary Prinz and his colleagues at the Naval Research Laboratory (NRL) in Washington, D.c), exploits the fact that the electrical resistance of some materials changes in the presence of magnetic field— a phenomenon known as magneto- resistance. For some multi-layered materials this effect is particularly powerful and is, accordingly, called “giant” magneto-resistance (GMR). Since 1997, the exploitation of GMR has made cheap multi-gigabyte hard disks commonplace. The magnetic orientations of the magnetised spots on the surface of a spinning disk are detected by measuring the changes they induce in the resistance of a tiny sensor. This technique is so sensitive that it means the spots can be made smaller and packed closer together than was previously possible, thus increasing the capacity and reducing the size and cost of a disk drive. Dr. Prinz and his colleagues are now exploiting the same phenomenon on the surface of memory chips, rather spinning disks. In a conventional memory chip, each binary digit (bit) of data is represented using a capacitor-reservoir of electrical charge that is either empty or fill -to represent a zero or a one. In the NRL’s magnetic design, by contrast, each bit is stored in a magnetic element in the form of a vertical pillar of magnetisable material. A matrix of wires passing above and below the elements allows each to be magnetised, either clockwise or anti-clockwise, to represent zero or one. Another set of wires allows current to pass through any particular element. By measuring an element’s resistance you can determine its magnetic orientation, and hence whether it is storing a zero or a one. Since the elements retain their magnetic orientation even when the power is off, the result is non-volatile memory. Unlike the elements of an electronic memory, a magnetic memory’s elements are not easily disrupted by radiation. And compared with electronic memories, whose capacitors need constant topping up, magnetic memories are simpler and consume less power. The NRL researchers plan to commercialise their device through a company called Non-V olatile Electronics, which recently began work on the necessary processing and fabrication techniques. But it will be some years before the first chips roll off the production line.Most attention in the field in focused on an alternative approach based on magnetic tunnel-junctions (MTJs), which are being investigated by researchers at chipmakers such as IBM, Motorola, Siemens and Hewlett-Packard. IBM’s research team, led by Stuart Parkin, has already created a 500-element working prototype that operates at 20 times the speed of conventional memory chips and consumes 1% of the power. Each element consists of a sandwich of two layers of magnetisable material separated by a barrier of aluminium oxide just four or five atoms thick. The polarisation of lower magnetisable layer is fixed in one direction, but that of the upper layer can be set (again, by passing a current through a matrix of control wires) either to the left or to the right, to store a zero or a one. The polarisations of the two layers are then either the same or opposite directions.Although the aluminum-oxide barrier is an electrical insulator, it is so thin that electrons are able to jump across it via a quantum-mechanical effect called tunnelling. It turns out that such tunnelling is easier when the two magnetic layers are polarised in the same direction than when they are polarised in opposite directions. So, by measuring the current that flows through the sandwich, it is possible to determine the alignment of the topmost layer, and hence whether it is storing a zero or a one.To build a full-scale memory chip based on MTJs is, however, no easy matter. According to Paulo Freitas, an expert on chip manufacturing at the Technical University of Lisbon, magnetic memory elements will have to become far smaller and more reliable than current prototypes if they are to compete with electronic memory. At the same time, they will have to be sensitive enough to respond when the appropriate wires in the control matrix are switched on, but not so sensitive that they respond when a neighbouring elements is changed. Despite these difficulties, the general consensus is that MTJs are the more promising ideas. Dr. Parkin says his group evaluated the GMR approach and decided not to pursue it, despite the fact that IBM pioneered GMR in hard disks. Dr. Prinz, however, contends that his plan will eventually offer higher storage densities and lower production costs.Not content with shaking up the multi-billion-dollar market for computer memory, some researchers have even more ambitious plans for magnetic computing. In a paper published last month in Science, Russell Cowburn and Mark Well and of Cambridge University outlined research that could form the basis of a magnetic microprocessor — a chip capable of manipulating (rather than merely storing) information magnetically. In place of conducting wires, a magnetic processor would have rows of magnetic dots, each of which could be polarised in one of two directions. Individual bits of information would travel down the rows as magnetic pulses, changing the orientation of the dots as they went. Dr. Cowbum and Dr. Welland have demonstrated how a logic gate (the basic element of a microprocessor) could work in such a scheme. In their experiment, they fed a signal in at one end of the chain of dots and used a second signal to control whether it propagated along the chain.It is, admittedly, a long way from a single logic gate to a full microprocessor, but this was true also when the transistor was first invented. Dr. Cowburn, who is now searching for backers to help commercialise the technology, says he believes it will be at least ten years before the first magnetic microprocessor is constructed. But other researchers in the field agree that such a chip, is the next logical step. Dr. Prinz says that once magnetic memory is sorted out “the target is to go after the logic circuits.” Whether all-magnetic computers will ever be able to compete with other contenders that are jostling to knock electronics off its perch — such as optical, biological and quantum computing — remains to be seen. Dr. Cowburn suggests that the future lies with hybrid machines that use different technologies. But computing with magnetism evidently has an attraction all its own.In developing magnetic memory chips to replace the electronic ones, two alternative research paths are being pursued. These are approaches based on:
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MCQ-> The pages of a book are numbered 0, 1, 2 . upto M, M>0. There are four categories of instructions that direct a person in positioning the book at a page. The instruction types and their meanings are : 1. OPEN : Position the book at page No. 1 2. CLOSE : Position the book at page No. 0 3. FORWARD, n :From the current page move forward by n pages; if, in this process, page number M is reached, stop at M. 4. BACKWARD, n : From the current page, move backward by n pages; if in this process, page number 0 is reached, stop at page number 0. In each of the following questions, you will find a sequence of instructions formed from the above categories. In each case, let n1 be the page number before the instructions are executed and n2 be the page number at which the book is positioned after the instructions are executed.FORWARD, 25 ; BACKWARD, 10. which of the following statements is true?
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MCQ-> Read the following passages carefully and answer the questions given at the end of each passage.PASSAGE 1In a study of 150 emerging nations looking back fifty years, it was found that the single most powerful driver of economic booms was sustained growth in exports especially of manufactured products. Exporting simple manufactured goods not only increases income and consumption at home, it generates foreign revenues that allow the country to import the machinery and materials needed to improve its factories without running up huge foreign bills and debts. In short, in the case of manufacturing, one good investment leads to another. Once an economy starts down the manufacturing path, its momentum can carry it in the right direction for some time. When the ratio of investment to GDP surpasses 30 percent, it tends to stick at the level for almost nine years (on an average). The reason being that many of these nations seemed to show a strong leadership commitment to investment, particularly to investment in manufacturing. Today various international authorities have estimated that the emerging world need many trillions of dollars in investment on these kinds of transport and communication networks. The modern outlier is India where investment as a share of the economy exceeded 30 percent of GDP over the course of the 2000s, but little of that money went into factories. Indian manufacturing had been stagnant for decades at around 15 percent of GDP. The stagnation stems from the failures of the state to build functioning ports and power plants and to create an environment in which the rules governing labour, land and capital are designed and enforced in a way that encourages entrepreneurs to invest, particularly in factories. India has disappointed on both counts creating labour friendly rules and workable land acquisition norms. Between 1989 and 2010 India generated about ten million new jobs in manufacturing, but nearly all those jobs were created in enterprises that are small and informal and thus better suited to dodge India’s bureaucracy and its extremely restrictive rules regarding firing workers It is commonly said in India that the labour laws are so onerous that it is practically impossible to comply with even half of them without violating the other half.Informal shops, many of them one man operations, now account for 39 percent of India’s manufacturing workforce, up from 19 percent in 1989 and they are simply too small to compete in global markets. Harvard economist Dani Rodrik calls manufacturing the “automatic escalator” of development, because once a country finds a niche in global manufacturing, productivity often seems to start rising automatically. During its boom years India was growing in large part on the strength of investment in technology service industries, not manufacturing. This was put forward as a development strategy. Instead of growing richer by exporting even more advanced manufactured products, India could grow rich by exporting the services demanded in this new information age. These arguments began to gain traction early in the 2010s.In new research on the “service escalators”, a 2014 working paper from the World Bank made the case that the old growth escalator in manufacturing was already giving way to a new one in service industries. The report argued that while manufacturing is in retreat as a share of the global economy and is producing fewer jobs, services are still growing, contributing more to growth in output and jobs for nations rich and poor. However, one basic problem with the idea of service escalator is that in the emerging world most of the new service jobs are still in very traditional ventures. A decade on, India’s tech sector is still providing relatively simple IT services mainly in the same back office operations it started with and the number of new jobs it is creating is relatively small. In India, only about two million people work in IT services, or less than 1 percent of the workforce. So far the rise of these service industries has not been big enough to drive the mass modernisation of rural farm economies. People can move quickly from working in the fields to working on an assembly line, because both rely for the most part on manual labour. The leap from the farm to the modern service sector is much tougher since those jobs often require advanced skills. Workers who have moved into IT service jobs have generally come from a pool of relatively better educated members of the urban middle class, who speak English and have atleast some facility with computers. Finding jobs for the underemployed middle class is important but there are limits to how deeply it can transform the economy, because it is a relatively small part of the population. For now, the rule is still factories first, not service first.According to the information in the above passage, manufacturing in India has been stagnant because there is
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