Computer disks (large and small) have internal drives that store data. Key components in the drives are the “heads” that actually read/write the data. Heads are manufactured in clean rooms by a series of steps that deposit layers of materials on a wafer, and pattern those layers using photolithography and etching. During the processing the wafers are inspected and, when processing is finished, the devices are tested. As a result of the manufacturing process, a head could have 2 active elements that are:
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