Software used to drive microprocessor based system is called

Scott Nadal E. Lee Byung-chul -- View Answer 4. Which of the following devices is widely used in modern digital cameras to store photographs? USB Flash drive C. Memory Card D. DVD E. None of the above -- View Answer 5. Unit time in which data can be read from or written to a memory storage device is referred to as A.

General Knowledge. General Science. General English. General Computer Science. General Intellingence and Reasoning. Current Affairs. Elementary Mathematics. English Literature. B firmware. 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. 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. Since the elements retain their magnetic orientation even when the power is off, the result is non-volatile memory. 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. 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. 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. 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. 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. 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.

Attempt a small test to analyze your preparation level. The questions asked in this NET practice paper are from various previous year papers.

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