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UNIVAC I Magnetic Tape Drive Units, c. 1952
Credit: Remington-Rand Corporation
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Storage, or “secondary memory”, is a place for keeping data and instructions that are not immediately required by the CPU. Storage systems are slower than main memory systems but have more capacity and are less expensive per bit. Many different storage mechanisms have been devised over the years. Most of these systems, such as tapes, disks and drums, store information by magnetizing tiny areas on a rapidly moving surface using a small electromagnet. But some unusual approaches were also developed: the IBM Photostore, for example, used a photographic process to store over one trillion bits of information on a collection of small plastic cards — in 1969!
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