[SHENGTON]

Hello guys, good morning.

Awhile ago, I'm having a research about "How Hard Disk Works?" and Google gave me the of HowStuffWorks. While reading the topic "Cassette Tape vs. Hard Disk" this line makes me curios.

In a cassette-tape deck, the read/write head touches the tape directly. In a hard disk, the read/write head "flies" over the disk, never actually touching it.

Can somebody explain this more deeply little bit. I mean, how the data is being read and write without touching the platter?

Hope somebody will give a brief explanation with this.

Edited by SHENGTON, 06 January 2011 - 09:05 PM.

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The heads float on a cushion of air.

If you'd read further down the list of Google results, you'd have found this:
http://www.pcmech.co...-how-they-work/

[Neil Jones]

The heads float on a cushion of air.

If you'd read further down the list of Google results, you'd have found this:
http://www.pcmech.co...-how-they-work/

[Digerati]

It is important to remember that data on hard drives is stored on these "magnetic" disks or platters by arranging "magnetic" particles in such a way that they represent either a 1 or a 0. If you hold a magnet just off a refrigerator door, you can still feel the pull without the magnet actually touching the door. The read head works the same way. It moves over the magnetic particles and "feels" the pull and determines the alignment.

Magnetic tape works the same way but remember tape is ancient technology. The magnetic particles on the tape are the size of mountains compared to those on a disk. And it took a lot of magnetic power to move those mountains so the tape heads (also of ancient technology) were also huge and no where near as precise. To ensure the tape head only moved the mountains it needed to, it had to get in close. But it still did not actually touch the magnetic particles of the tape, it touched the layer of smooth material, typically polymer.