Why would a delay gate be needed for a digital circuit? ?->(Show Answer!)

1. Why would a delay gate be needed for a digital circuit?

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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->Which of the following conditions should be satisfied to call an astable multivibrator circuit using discrete components as a digital circuit? A flip-flop is always a digital circuit. Only when we assign 1 and 0 to the high and low levels of the output, a flip-flop is called a digital circuit. Only if the power, supply voltage is maintained at + 5 V or - 5 V, it is called a digital circuit. Only if it is in IC form, following the technology of IC manufacture, it is called a digital circuit.Select the correct answer from the codes given below:....

MCQ-> Read the following passage carefully and answer the question given below it. Certain words/phrases have been printed in bold to help you locate them while answering some of the questions. There was a country long time ago where the people would change a king every year. The person who would become the king had to agree to a contract that he would be sent to an island after one year of his being a king. One King had finished his term and it was time for him to go to the island and live there.The people dressed him up in expensive clothes and put him on an elephant and took him to around the cities to say goodbye to all the people. This was a moment of sadness for all kings who ruled for one year. After bidding farewell the people took the king to a remote island in a boat and left him there. On their way back they discovered a ship that had sunk just recently.They saw a young man who survived by holding on to a floating piece of wood. As they needed a new king, they picked up the young man and took him to their country. They requested him to be king for a year. First he refused but later he agreed to be the king. People told him about all the rules and regulations and about how he would be sent to an island after one year. After three days of being a king he asked the ministers if they could show him the island where all the other kings were sent. They agreed and took him to the island. The island was covered with a thick jungle and sounds of vicious animals were heard coming out of it. The king went a little bit further to check. Soon he discovered dead bodies of all the past kings.He understood that as soon as they were left on the island the wild animals had come and killed them. The king went back to the country and collected 100 strong workers. He took them to the island and instructed them to clean the jungle, remove all the deadly animals and cut down all excess trees. He would visit the island every month to see how the work was progressing. In the first month all the animals were removed and many trees were cut down. In the second month all the island were cleaned out. The king then told the workers to plant gardens in various parts of the island. He also took with himself useful animals like chickens, ducks, birds, goats,cows etc. In the third month he ordered the workers to build big house and docking stations for ships. Over the months the island turned into a beautiful place. The young king would wear simple clothes and spend very little from his earning as a king. He sent all the earnings to the island for storage. When nine months passed like this the king called the ministers and told them “I know that I have go to the island after one year but I would like to go there right now. But the ministers didn’t agree to this and said that he had to wait for another three months to complete the year. Three months passed and now it was a full year. The people dressed up the young king and put on an elephant to take him around the country to say goodbye to others. However this king was unusually happy to leave the kingdom. People asked him "All the other kings would cry at this moment. Why is it that you are laughing?". He replied “Don’t you know what the wise people say? They say that when you come to this world as a baby you are crying and everyone else is smiling. Live such a life that when you die you will be smiling and everyone around you will be crying. I have lived that life. While all the other kings were lost into the luxuries of the kingdom, I always thought about the future and planned for it. I turned the deadly island into a beautiful abode for me where I can stay peacefully”.Why did the people of the kingdom change the king every year ?
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MCQ-> Study the following information carefully and answer the given questions: A word and number arrangement machine when given an input line of words and numbers rearranges them following a particular rule in each step. The following is an illustration of input and rearrangement. (All the numbers are two digits numbers.)Input : gate 20 86 just not 71 for 67 38 bake sun 55 Step I : bake gate 20 just not 71 for 67 38 sun 55 86 Step II : for bake gate 20 just not 67 38 sun 55 86 71 Step III : gate for bake 20 just not 38 sun 55 86 71 67 Step IV : just gate for bake 20 not 38 sun 86 71 67 55 Step V : not just gate for bake 20 sun 86 71 67 55 38 Step VI : sun not just gate for bake 86 71 67 55 38 20 and Step VI is the last step of the above input as the desired arrangement is reached. As per the rules followed in the above steps, and out in each of the following questions the appropriate step for the given input. Input : 31 rise gem 15 92 47 aim big 25 does 56 not 85 63 with moonHow many steps will be required to complete the rearrangement ?
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MCQ-> It’s taken me 60 years, but I had an epiphany recently: Everything, without exception, requires additional energy and order to maintain itself. I knew this in the abstract as the famous second law of thermodynamics, which states that everything is falling apart slowly. This realization is not just the lament of a person getting older. Long ago I learnt that even the most inanimate things we know of ―stone, iron columns, copper pipes, gravel roads, a piece of paper ―won’t last very long without attention and fixing and the loan of additional order. Existence, it seems, is chiefly maintenance.What has surprised me recently is how unstable even the intangible is. Keeping a website or a software program afloat is like keeping a yacht afloat It is a black hole for attention. I can understand why a mechanical device like a pump would break down after a while ―moisture rusts metal, or the air oxidizes membranes, or lubricants evaporate, all of which require repair. But I wasn’t thinking that the nonmaterial world of bits would also degrade. What’s to break? Apparently everything.Brand-new computers will ossify. Apps weaken with use. Code corrodes. Fresh software just released will immediately begin to fray. On their own ―nothing you did. The more complex the gear, the more (not less) attention it will require. The natural inclination toward change is inescapable, even for the most abstract entities we know of: bits.And then there is the assault of the changing digital landscape. When everything around you is upgrading, this puts pressure on your digital system and necessitates maintenance. You may not want to upgrade, but you must because everyone else is. It’s an upgrade arms race.I used to upgrade my gear begrudgingly (Why upgrade if it still works?) and at the last possible moment. You know how it goes: Upgrade this and suddenly you need to upgrade that, which triggers upgrades everywhere. I would put it off for years because I had the experiences of one “tiny” upgrade of a minor part disrupting my entire working life. But as our personal technology is becoming more complex, more co-dependents upon peripherals, more like a living ecosystem, delaying upgrading is even more disruptive. If you neglect ongoing minor upgrades, the change backs up so much that the eventual big upgrade reaches traumatic proportions. So I now see upgrading as a type of hygiene: You do it regularly to keep your tech healthy. Continual upgrades are so critical for technological systems that they are now automatic for the major personal computer operating systems and some software apps. Behind the scenes, the machines will upgrade themselves, slowly changing their features over time. This happens gradually, so we don‘t notice they are “becoming.”We take this evolution as normal.Technological life in the future will be a series of endless upgrades. And the rate of graduations is accelerating. Features shift, defaults disappear, menus morph. I’ll open up a software package I don’t use every day expecting certain choices, and whole menus will have disappeared.No matter how long you have been using a tool, endless upgrades make you into a newbie ―the new user often seen as clueless. In this era of “becoming” everyone becomes a newbie. Worse, we will be newbies forever. That should keep us humble.That bears repeating. All of us ―every one of us ―will be endless newbies in the future simply trying to keep up. Here’s why: First, most of the important technologies that will dominate life 30 years from now have not yet been invented, so naturally you’ll be a newbie to them. Second, because the new technology requires endless upgrades, you will remain in the newbie state. Third, because the cycle of obsolescence is accelerating (the average lifespan of a phone app is a mere 30 days!), you won’t have time to master anything before it is displaced, so you will remain in the newbie mode forever. Endless Newbie is the new default for everyone, no matter your age or experience.Which of the following statements would the author agree with the most?
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