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Hard drives (or hard disk drives) are electronic devices that can store/retrieve digital information on/from a physical medium called a platter. The storage is non-volatile in that no power is consumed to maintain the information. The physical principle for the information storage is to create magnetic patterns on the platter (which is a magnetic material). The part of the device that reads or writes the data is the read/write head that floats on a cushion of air above the platter. The first hard drive was invented by IBM in 1956. Hard disk drives are sometimes called Winchester drives, which is the name of one of the first popular hard disk drive technologies developed by IBM in 1973. There are several industry standards to specify and control transferring data back and forth between a hard disk and a computer. The most common are called IDE and SCSI. |
 Internal View of a Hard Drive |