Shopping for Hard Drive
By
Kevin Saporito
The hard drive is a disk coated with magnetic iron oxide particles. The disk spins continuously very fast in your computer and the head can travel in and out along a radius so that any location can be reached very quickly by the head. Although the head may look large, actually the sensitive part of the head is defined by microlithographic methods so that the actual exposed portion of the head, which can either read or write the informaion on the disk,is very small-comparable to the dimensions of features on a microchip! As the manufacturing technology has improved over the years they have been able to shrink this area down to smaller and smaller sizes, and that is how the hard disk memories have risen to such large figures now. In addition they have increased the density of magnetic particles on the disk which makes the storage capacity larger. For example in 1991 the density of storage memory was about 0.l3 Gbits/square inch. In 1998 it was up to around 4 Gbits (30X the density!). At the same time the lithography limit of the sensitive head area was about 4.5 uMeters in 1991, and in 1998 was down to 0.5 uMeters, reduced by a factor of 9. So that is how the storage density of the disks is now up to 30 GB or higher. The information is stored in circular patterns on the disk and the location of the rings is measured by the computer and the spatial resolution is very high, so the location of the head to find data on the disk is exceedingly precise!
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$189.99 |
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$142.99 |
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$273.99 |
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$253.99 |
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$139.99 |