Blackwell Reference Online

Extract

Digital storage technologies originated in the mid‐1940s with the advent of the digital computer. Special data storage devices were used to store data that would not fit into the computer's memory space and data that needed to be retained even when the power to the computer system was removed. These are referred to as “permanent” data storage “peripherals” – “permanent” because of their ability to retain their data indefinitely, and “peripheral” because they existed at the periphery of the computer system whose center was the central processing unit (CPU). There have been many different types of permanent data storage technologies employed over the past 60 years, but the most enduring are magnetic, optical, and, more recently, flash memory devices. At the time of this writing, these storage devices are almost ubiquitous in western society and will most likely be more widespread in the coming years. Permanent magnetic storage first appeared in the 1940s as magnetic tape. This tape was a flexible, thin plastic tape about 1 inch wide with a thin coating of a ferrous magnetic material applied to one side. Data were recorded by passing the tape under a magnetic recording “head” that would set the magnetic orientation of the ferrous magnetic material in one of two directions on a very small piece of the tape, usually about 1/500th of an inch long. This would constitute a single digital ... log in or subscribe to read full text