Reading Comprehension Quiz
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Q.Read the following passage carefully and answer the questions given below it. Certain words are given in bold to help you locate them while answering some of the questions.
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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 electronic ones. These magnetic memories would be non-volatile; but they would also be faster, would have obvious applications in storage cards for digital cameras and music players; they would enable handheld and laptop 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-farming advantages too. But although the theory behind them looks solid, there are tricky practical probl ems that 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 a magneti field- a phenomenon known as magneto-resistance. For some multilayered materials, this effect is particularly powerful and is accordingly called ‘giant’ 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 magnetized 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 disk drive. Dr. Prinz and his colleagues are now exploiting the same phenomenon on the surface of memory chips, rather than 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 full- 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 magnetized, either clockwise or anticlockwise, to represent zero or one. Another set wires allows current to pass through any particular element. By measuring an elements’ 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 o꣖�, 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 commercialize their device through a company called Non-Volatile 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 is focused on an alternative approach based on magnetic tunnel junction (MTJs), which are being investigated by researchers at chip makers, such as IBM, Motorola, Siemens and Hawlett 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 one percent of the power. Each element consists of a sandwich of two layers of magnetisable material separated by a barrier of aluminum oxide just four or five atoms thick. The polarization of lower magnetisable layer is fixed in the 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 polarizations of the two layers are then in 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 quantum-mechanical effect called tunneling. It turns out that such tunneling is easier when the two magnetic layers are polarized in the same direction than when they are polarized 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 neighboring element is changed. Despite these diffculties, the general consensus is that MTJs are the more promising idea. 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 is Science, Russell Cowburn and Mark Welland of Cambridge University outlined research that could from the basis of a magnetic microprocessor 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 polarized 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. Cowburn and DrWelland 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 commercialize the technology, says he believes it will be at least 10 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 see. Dr. Cowbrun suggests that the future lies with hybrid machines that use different that use different technologies. But computing with magnetism evidently has an attraction all its own.
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1.In developing memory chips to replace the electronics ones, two alternative research paths are
being pursued. These are approaches based on:
A. Volatile and non-volatile memories.
B. magneto- resistance and magnetic tunnel-junctions.
C. Radiation disruption and radiation neutral effect.
D. Orientation of magnetized spots on the surface of a spinning disk and alignment of magnetic
dots on the surface of a conventional memory chip
E. None of the above
2.A binary digit or bit is represented in the magneto-resistance based magnetic chip using:
A. A layer of aluminum oxide
B. A capacitor
C. A vertical pillar of magnetized material
D. A matrix of wires
E. None of the above
3.In the magnetic tunnel-junctions (MTJs) tunneling is easier when:
A. Two magnetic layers are polarized in the same direction.
B. Two magnetic layers are polarized in the opposite directions.
C. Two aluminum-oxide barriers are polarized in the same direction.
D. Two aluminum-oxide barriers are polarized in the opposite directions.
E. None of the above
4.A major barrier on the way to build a full-scale memory chip based on MTJ is :
A. The low sensitivity of the magnetic memory elements.
B. The thickness of aluminum oxide barriers.
C. The need to develop more reliable and far smaller magnetic memory chips
D. All of the above.
E. None of the above
5.In the MTJs approach, it is possible to identify whether the topmost layer of the magnetized memory element is storing a zero or one by:
A. Measuring an element’s resistance and thus determining its magnetic orientation.
B. Measuring the degree of disruption caused by radiation in the elements of the magnetic memory.
C. Magnet sing the elements either clockwise or anticlockwise
D. Measuring the current that flows through the sandwich.
E. None of the above
6.A line of research which is trying to build a magnetic chip that can both store and manipulate
information is being pursued by-
A. Paul Freitas
B. Stuart Parkin
C. Gray Prinz.
D. None of the above
E. All of the above
7.Experimental research current underway, using rows of magnetic dots, each of which could be
polarized in one of the two directions, led to the demonstration of:
A. working of a microprocessor
B. working of a logic gate
C. working of a magneto-resistance based chip
D. working of a magneto tunneling-junction (MTJ) based chip.
E. None of the above
8.From the passage, which of the following cannot be inferred?
A. Electronic memory chips are faster and non-volatile.
B. Electronic and magnetic storage technologies play a complementary role.
C. MTJ are the more promising idea compared to the magneto-resistance approach.
D. Non-volatile electronics is the company set up to commercialize the GMR chips.
E. None of the above
9.Choose the word/group of words which is most similar in meaning to the word/group of words printed in bold as used in passage. Magnetized
10.Choose the word/group of words which is most similar in meaning to the word/group of words printed in bold as used in passage. Pioneered
- B. magneto- resistance and magnetic tunnel-junctions. [ The answer to this question can be found in the beginning phase of 2nd, 3rd and 5th paragraph.]
- C. A vertical pillar of magnetized material. [ This can be found from the second sentence of the 4th paragraph.]
- A. Two magnetic layers are polarized in the same direction. [ This can be found from the second sentence of the 6th paragraph.]
- C. The need to develop more reliable and far smaller magnetic memory chips. [ This can be found from the 2nd sentence of the 7th paragraph.]
- D. Measuring the current that flows through the sandwich. [ This can be found from the last sentence of the 6th paragraph.]
- D. None of the above
- B. working of a logic gate [ This can be found from the latter part of the 8th paragraph.]
- A. Electronic memory chips are faster and non-volatile. [ In the second sentence of the 1st paragraph helps us identify option (A) as the right answer.]
- C. allure [Allure means the quality of being powerfully and mysteriously attractive or fascinating.]
- D. spearhead [ Pioneered means develop or be the first to use or apply (a new method, area of knowledge, or
activity) and spearhead means an individual or group chosen to lead an attack or movement.]
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