20 June 2009

Floppy disk

The invention: Inexpensive magnetic medium for storing and moving computer data. The people behind the invention: Andrew D. Booth (1918- ), an English inventor who developed paper disks as a storage medium Reynold B. Johnson (1906-1998), a design engineer at IBM’s research facility who oversaw development of magnetic disk storage devices Alan Shugart (1930- ), an engineer at IBM’s research laboratory who first developed the floppy disk as a means of mass storage for mainframe computers First Tries When the International Business Machines (IBM) Corporation decided to concentrate on the development of computers for business use in the 1950’s, it faced a problem that had troubled the earliest computer designers: how to store data reliably and inexpensively. In the early days of computers (the early 1940’s), a number of ideas were tried. The English inventor Andrew D. Booth produced spinning paper disks on which he stored data by means of punched holes, only to abandon the idea because of the insurmountable engineering problems he foresaw. The next step was “punched” cards, an idea first used when the French inventor Joseph-Marie Jacquard invented an automatic weaving loom for which patterns were stored in pasteboard cards. The idea was refined by the English mathematician and inventor Charles Babbage for use in his “analytical engine,” an attempt to build a kind of computing machine. Although it was simple and reliable, it was not fast enough, nor did it store enough data, to be truly practical. The Ampex Corporation demonstrated its first magnetic audiotape recorder after World War II (1939-1945). Shortly after that, the Binary Automatic Computer (BINAC) was introduced with a storage device that appeared to be a large tape recorder. A more advanced machine, the Universal Automatic Computer (UNIVAC), used metal tape instead of plastic (plastic was easily stretched or even broken). Unfortunately, metal tape was considerably heavier, and its edges were razor-sharp and thus dangerous. Improvements in plastic tape eventually produced sturdy media, and magnetic tape became (and remains) a practical medium for storage of computer data. Still later designs combined Booth’s spinning paper disks with magnetic technology to produce rapidly rotating “drums.” Whereas a tape might have to be fast-forwarded nearly to its end to locate a specific piece of data, a drum rotating at speeds up to 12,500 revolutions per minute (rpm) could retrieve data very quickly and could store more than 1 million bits (or approximately 125 kilobytes) of data. In May, 1955, these drums evolved, under the direction of Reynold B. Johnson, into IBM’s hard disk unit. The hard disk unit consisted of fifty platters, each 2 feet in diameter, rotating at 1,200 rpm. Both sides of the disk could be used to store information. When the operator wished to access the disk, at his or her command a read/write head was moved to the right disk and to the side of the disk that held the desired data. The operator could then read data from or record data onto the disk. To speed things even more, the next version of the device, similar in design, employed one hundred read/write heads—one for each of its fifty double-sided disks. The only remaining disadvantage was its size, which earned IBM’s first commercial unit the nickname “jukebox.” The First Floppy The floppy disk drive developed directly from hard disk technology. It did not take shape until the late 1960’s under the direction of Alan Shugart (it was announced by IBM as a ready product in 1970). First created to help restart the operating systems of mainframe computers that had gone dead, the floppy seemed in some ways to be a step back, for it operated more slowly than a hard disk drive and did not store as much data. Initially, it consisted of a single thin plastic disk eight inches in diameter and was developed without the protective envelope in which it is now universally encased. The addition of that jacket gave the floppy its single greatest advantage over the hard disk: portability with reliability. Another advantage soon became apparent: The floppy is resilient to damage. In a hard disk drive, the read/write heads must hover thousandths of a centimeter over the disk surface in order to attain maximum performance. Should even a small particle of dust get in the way, or should the drive unit be bumped too hard, the head may “crash” into the surface of the disk and ruin its magnetic coating; the result is a permanent loss of data. Because the floppy operates with the read-write head in contact with the flexible plastic disk surface, individual particles of dust or other contaminants are not nearly as likely to cause disaster. As a result of its advantages, the floppy disk was the logical choice for mass storage in personal computers (PCs), which were developed a few years after the floppy disk’s introduction. The floppy is still an important storage device even though hard disk drives for PCs have become less expensive. Moreover, manufacturers continually are developing new floppy formats and new floppy disks that can hold more data.Consequences Personal computing would have developed very differently were it not for the availability of inexpensive floppy disk drives. When IBM introduced its PC in 1981, the machine provided as standard equipment a connection for a cassette tape recorder as a storage device; a floppy disk was only an option (though an option few did not take). The awkwardness of tape drives—their slow speed and sequential nature of storing data—presented clear obstacles to the acceptance of the personal computer as a basic information tool. By contrast, the floppy drive gives computer users relatively fast storage at low cost. Floppy disks provided more than merely economical data storage. Since they are built to be removable (unlike hard drives), they represented a basic means of transferring data between machines. Indeed, prior to the popularization of local area networks (LANs), the floppy was known as a “sneaker” network: One merely carried the disk by foot to another computer. Floppy disks were long the primary means of distributing new software to users. Even the very flexible floppy showed itself to be quite resilient to the wear and tear of postal delivery. Later, the 3.5- inch disk improved upon the design of the original 8-inch and 5.25- inch floppies by protecting the disk medium within a hard plastic shell and by using a sliding metal door to protect the area where the read/write heads contact the disk. By the late 1990’s, floppy disks were giving way to new datastorage media, particularly CD-ROMs—durable laser-encoded disks that hold more than 700 megabytes of data. As the price of blank CDs dropped dramatically, floppy disks tended to be used mainly for short-term storage of small amounts of data. Floppy disks were also being used less and less for data distribution and transfer, as computer users turned increasingly to sending files via e-mail on the Internet, and software providers made their products available for downloading on Web sites.