Now You See It, Now You Don't!
TellZall's object for June is the Computer Disk
The rapid evolution of the electronic computer following World War II required engineers to overcome many obstacles. Among these was finding a method to permanently store information, or data.
Beginning in the late nineteenth century, engineers had used paper cards with holes punched in them to store information. These cards were used with mechanical calculating machines for a variety of purposes, especially for compiling vital statistics. These machines, however, were not true computers. With the advent of the ENIAC, the first electronic digital computer, in 1945, the modern programmable computer was born. ENIAC utilized programming to reduce greatly the time required for complex calculations. For example, ballistics calculations that took a person using a desk calculator twenty hours could be done by ENIAC in thirty seconds.
ENIAC used a punch-card reader to input information and a card-punch machine to record computations. These mechanical devices limited the speed with which this and future computers could operate, and a better means of data transfer and storage became a priority.
Magnetic tape became the answer. The tape could be imprinted with data and read back much quicker than a punch-card system. At first, the tape was wound onto reels and rolled and unrolled to find and read data. Mechanical problems often plagued the system, however. The rapid movement of the tape reels and problems associated with inertia caused tape breakage and limited speeds. In 1971, Alan Shugart of International Business Machines (IBM) mainframe computers began using large, eight-inch disks of magnetic medium to input information into computers. Shugart's system employed a "Memory Disk" of magnetic material, similar to audio recording tape, that was held by an electric drive at the center and spun. A read-write head, much like the head of an audio tape recorder, contacted the medium and either imprinted data onto it or read data from it. Shugart's original disk held about 100 kilobytes of information.
The new system was an immediate success, and it was adapted to other uses. With the advent of the small, desktop computer in the mid-1970s, Shugart in 1976 introduced a 5.25-inch-diameter disk encased in a plastic case. Because the magnetic medium and the case were not rigid, the name "floppy disk" quickly entered the computer lexicon. The first "floppies" held less than 100 kilobytes. Soon, however, the technology improved, and capacity reached 1.2 megabytes.
In 1980 Sony introduced a smaller, 3.5-inch diameter disk that was encased in rigid plastic. The new, more-robust disk, combined with much-improved drives, could store 1.5 megabytes. By the mid-1990s, the 5.25-inch floppy was largely forgotten. The continuing need for greater storage capacity lead to an entirely new technology, the CD-ROM (compact disk-read only memory). Introduced by Sony in 1986, the new medium was an offshoot of the audio compact disk that displaced vinyl records (See TellZall, April 2002). Although the CD-ROM could only be read by most desktop computers, it held an incredible 650 megabytes of information on a sturdy, plastic disk.
As CD-ROM technology evolved, the price of drives, including desktop drive that write information, decreases dramatically. The price of the plastic disks also dropped. By the late 1990s, the era of the magnetic disk was largely over. New computers no longer came equipped with disk drives, as the CD took over.
