Capacity is specified in unit prefixes corresponding to powers of 1000: a 1-terabyte (TB) drive has a capacity of 1,000 gigabytes (GB where 1 gigabyte = 1 billion bytes). The primary characteristics of an HDD are its capacity and performance. Worldwide revenues for HDD shipments are expected to reach $33 billion in 2013, a decrease of approximately 12% from $37.8 billion in 2012.
More than 200 companies have produced HDD units, though most current units are manufactured by Seagate, Toshiba and Western Digital. Continuously improved, HDDs have maintained this position into the modern era of servers and personal computers. Introduced by IBM in 1956, HDDs became the dominant secondary storage device for general purpose computers by the early 1960s. An HDD consists of one or more rigid ("hard") rapidly rotating disks (platters) with magnetic heads arranged on a moving actuator arm to read and write data to the surfaces. Data is read in a random-access manner, meaning individual blocks of data can be stored or retrieved in any order rather than sequentially.
An HDD retains its data even when powered off. For nearly every other component, including the operating system, there are several options, all of which fall under the rubric of PCĪ hard disk drive (HDD) is a data storage device used for storing and retrieving digital information using rapidly rotating disks (platters) coated with magnetic material.
In general, though, it applies to any personal computer based on an Intel microprocessor, or on an Intel-compatible microprocessor.
Dbmss available for use on personal computers include and corel paradox Pc#
In recent years, the term PC has become more and more difficult to pin down. Therefore after the release of the first PC by IBM the term PC increasingly came to mean IBM or IBM-compatible personal computers, to the exclusion of other types of personal computers, such as Macintoshes. Over the years, IBM has lost much of its influence in directing the evolution of PCs. Because IBM clones used the same microprocessors as IBM PCs, they were capable of running the same software. Other companies adjusted to IBM's dominance by building IBM clones, computers that were internally almost the same as the IBM PC, but that cost less. One of the few companies to survive IBM's onslaught was Apple Computer, which remains a major player in the personal computer marketplace. is short for personal computer or IBM PC. The IBM PC quickly became the personal computer of choice, and most other personal computer manufacturers fell by the wayside. Then, in 1981, IBM entered the fray with its first personal computer, known as the IBM PC. During the late 1970s and early 1980s, new models and competing operating systems seemed to appear daily. One of the first and most popular personal computers was the Apple II, introduced in 1977 by Apple Computer. Personal computers first appeared in the late 1970s. The distinction between small mainframes and minicomputers is vague, depending really on how the manufacturer wants to market its machines. But supercomputers can execute a single program faster than a mainframe. In some ways, mainframes are more powerful than supercomputers because they support more simultaneous programs. The chief difference between a supercomputer and a mainframe is that a supercomputer channels all its power into executing a few programs as fast as possible, whereas a mainframe uses its power to execute many programs concurrently. Nowadays a Mainframe is a very large and expensive computer capable of supporting hundreds, or even thousands, of users simultaneously. After the emergence of smaller "minicomputer" designs in the early 1970s, the traditional big iron machines were described as "mainframe computers" and eventually just as mainframes. Mainframe was a term originally referring to the cabinet containing the central processor unit or "main frame" of a room-filling Stone Age batch machine.
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