Evolutionary advances represent the marginal improvements made to successive generations of a product. Revolutionary advances, on the other hand, are those that significantly change the horizon for their industry, and thereby impact the products of associated industries. MR heads allow drive manufacturers to increase the capacity of drives without sacrificing performance or significantly increasing costs. Furthermore, MR heads have unique properties which make them especially useful for small form-factor drives. The data storage industry is trying to place the maximum amount of storage in the smallest size possible, and MR heads will become one of the important facilitators in this migration.
Most disc drives built today use conventional thin-film recording heads.
In essence, these heads are similar to the recording head on an audio cassette player, where the read element of the head detects changes in the magnetic flux on the surface of the recording media. When a conventional thin-film head passes over a magnetic field, it generates a minute signal which is subsequently amplified, filtered and converted into its digital representation by the electronics on the drive's circuit board. MR heads operate on a completely different physical phenomenon known as the magneto-resistive effect. Certain metals, when exposed to a magnetic field, change their resistance to the flow of electricity. This property is exploited in creating the read element of an MR head.