A low-density drive will not be able to write to these disks because its drive head does not produce a strong enough magnetic field.įor a low density disk written with a high density drive head, the signal intensity is stronger but also smaller, but with also a stronger unfocused fringe around the drive head. If the tracks are space too closely together, this fringing can partially overwrite the magnetic patterns of adjacent tracks.įor a high density disk, the media has a much higher coercivity. On most disks there is usually up to a full track width of space between adjacent tracks, because in addition to writing an imprint of a magnetic field directly underneath the drive head, there will be an additional unfocused fringe of a magnetic field around the edges of the drive head. Magnetic media needs to be able to resist casual demagnetization by the Earth's magnetic field, from other magnetic media placed near it, but most importantly from other data written directly onto the media. The way that magnetic media works is that it has a coating that can retain a magnetic field that has been imprinted on it, and it has a resistance to demagnetization / remagnetization, known as coercitvity. but eventually the low density disks written with high density data can start to develop data errors and become corrupted and unreadable.
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