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A few years ago, a query about the health of a person’s hard disk drive would have been met with a blank stare. Nowadays, almost everyone is aware of this remarkable electronic storage medium that is part of every modern computer, even though most users remain ignorant of the complexity of hard drive technology.
In the early days of computing, an information record of a computer’ s memory content was kept on punched cards similar to the way in which an automated piano stores the keynote sequences on a piano roll. Later, magnetic tape was used to store electronic signals, and is still the favoured means of economically backing up the contents of hard drives. However, accessing information sequentially stored on tape is slow since the electroniodata must be input through a fixed head in a single pass.
Hard disk drives solve this problem by incorporating a spinning platter on which magnetic data can be made accessible via a moving head that reads and writes information across the width of the disk. It is analogous to the way in which a person can choose to play a particular track on a CD player by causing the arm to move the head across the disk. The CD player is, in fact, necessarily similar in design to a hard drive, although there are significant differences in speed of data access.
Most modern hard drives incorporate several platters to further reduce the time spent seeking the required information. Also, some newer drives have two heads; one for reading, and a second head for writing data to disk. This separation of tasks enables much higher densities of magnetic information to be written on the platter, which increases the capacity of the hard drive.
There are three important ways in which the capacity of hard disks has been increased. First, the data code itself has been tightened with express coding techniques. Second, as previously noted, the head technology has been improved; and third, the distance between the heads and the platters has been greatly reduced. It is hard to believe, but the head can be made to pass over the magnetised platter at distances of less than 1 microinch (the width of a typical human hair is 5000 microinches). This is achieved by means of a special protective coating applied to the platter. Each of these three improvements enables speedier access to the data.
Hard drives are more commonplace than tape recorders these days, but it must be remembered that they are much more fragile. Treated with respect they may last a number of years, but they are quite easily damaged, often with disastrous consequences for the user, whose precious data can become lost forever. Dropping a drive is almost always fatal, as is passing an incorrect electrical current through one (by faulty connection). Dust and even extremes of temperature can cause failure. Yet, no physical damage can ever result from the input of data via the keyboard or mouse. Of course, over time the magnetised coating on the platters will erode, yet this is almost entirely independent of the amount of use.
There are serious questions being raised about the direction of the future of electronic storage media. Some researchers claim that it would be wiser to invest more time and money in setting up systems for streaming data across networks of computers from centralised banks of information storage. This would avoid the need for each personal computer user to have his or her own copy of a software program resident on a local hard drive. Personal data files could be kept at a central storage unit, and be suitably protected from disaster by a failsafe backup system.
As the Internet becomes ever more pervasive, and the speed of access to other machines increases across our telephone lines, it might be possible to do away with local storage systems altogether.
backing up — duplicating
sequential(ly) — in sequence (or one after the other)
platter — circular disk or plate
Streaming data — sending or broadcasting information as data
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