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Analysis: Perpendicular Versus Horizontal Drive Technology

Hard drives haven't really undergone any truly revolutionary changes in decades, possibly since the move to integrated drive electronics (IDE). Sure, they've received upgrades to areal density so that current devices can hold far more than even their close ancestors of a few years ago and gobs more than the 10MB of the top of the line drives from the 1980s. We've also seen them switch from parallel ATA (PATA) to serial ATA (SATA) and watched as the industry endowed them with faster data access speeds, longer life spans, and enhanced reliability. Still, these have been more an evolution than revolution.

The one upgrade that has been revolutionary is the move from a horizontal to a perpendicular recording scheme. I can hear the head scratching in the back rows

Picture a dinner plate covered in a thin layer of lobster sauce. You've eaten the shrimp already so all that's left is the white rice sitting the sauce and, by some cosmic intervention, all of the grains are lying flat (horizontally!) on the plate, end to end, a spiral pattern that stretches from the outer rim of the plate to its center. (Some intervention, huh?)

The plate is analogous to a hard drive's substrate, the lobster sauce to the slurry that's used on that substrate to hold the ferric particles (the rice, in this case) in place. Hard disk manufacturers spin the substrate to get the particles to align as noted. We relied on cosmic intervention to keep you from being ejected from the restaurant.

You can employ a variety of techniques to pack more and more rice onto the dish in that manner but, at some point, the length of the rice (or the ferric particle) becomes the real limiting factor. Bottom line: you can only fit ten 1-micron wide particles in a 10-micron space.

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