Early Computer Storage Devices
The history of early computer storage devices requires a look back to the 1940s and the fledgling start of our modern era. Early computing machines were designed to take direct input and make calculations based on the positions of switches and relays. Manually configuring each and every function became tedious, and it was apparent that a need existed for some media to store information to be input and output.
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Vacuum Tubes
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The first 1940s-era digital computer named Electronic Numeral Integrator and Computer, or ENIAC, used vacuum tubes to make calculations and hold the data in accumulator tubes. The Selectron tube evolved out of this process in 1946 and was able to store 512 bytes of data. It was ten inches long and three inches wide. This is longer than some personal digital assistants (PDAs) and pocket computers today.
Punch Cards and Tape
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Two similar methods of storing and entering data were punch cards and paper tape. These methods both used a single row of punched holes to represent one byte of data or one character. The cards were easy to stack and compact, whereas the paper tape had to be kept in rolls. The paper tape was originally used in the textile industry where it controlled automated looms. It could also be used as an output device, as each row represented one character.
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Magnetic Drums
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These large cylinders of metal had a ferrous surface that could be magnetized. Tracks or magnetic stripes were recorded down the surface. The UNIVersal Automatic Computer, or UNIVAC, used a drum that was 16 inches long and had 40 tracks holding ten kilobytes of data.
Hard Disk Drive
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Out of the drum evolved the hard disk drive, and the original was a long way from what we know today as a hard disk. The disks or platters on the drive were two feet across in 1956 and could only hold approximately 5 megabytes of data. Hard drives that could hold more than a gig of data didn't come along until 1980. The first drive that could do that held just over 2.5 gig of data and was the size of a refrigerator.
Magnetic Tape
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Combining two ideas, magnetic tape held a great deal of data per inch of surface area, and was easy to roll up and store like the paper tape of the 1950s. At first, the tape was similar to tape used in audio recording and was kept on large reels and stored in carefully managed clean rooms. Later, as tape technology progressed, some of the first home computers stored data in this fashion on standard audio cassettes.
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References
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