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I blame the media

February 8, 2010 Leave a comment Go to comments

I finally did it.

I finally backed up all of my pictures, music, and important files and documents. I did this in preparation of reformatting my hard drive and reinstalling the OS. I’m doing this because I’m a geek and I can, but it’s also a means to an end to make a to back everything up. I also downloaded all of the install files for my favorite programs and put all of the important drivers on a flash drive. I now have an information disaster recovery program, so if something were to happen to my hard drive, all but the newest data is in an easy accessible location. Most of the data is on burned dvds, a lot of the music is saved to the empty space on my iPod, which has a little hard drive in it, and a few files are saved to a flash drive. Naturally this got me to wondering how these devices worked.

The iPod hard drive is a bit easier to explain and understand than the solid state flash drive. It’s made up of one (or a number) of rigid discs (called platters). The fact that it’s rigid is where it gets its name, as opposed to the old, pliable floppy discs. Also in the hard hard drive are a number of arms (one or two for each platter). The arms contain a read/write head which come very close to but never actually touch the platters. The write head receives information from the computer in the form of energy and creates a magnetic flux. The platter remembers this flux until it is rewritten. The read head passes over the pattern and reads the varying magnetic flux given off by the platter and converts that into data. It’s basically the same concept that is used in speakers, except instead of sound waves, it creates a magnetic flux.

It’s amazing how fast these get and how much information they can hold. The arms can move back and forth fifty times a second and the platters can rotate at 7200 rpms or about 170mph. Considering how precise hard drives have to be, it’s amazing that they aren’t failing left and right. We hold some serious trust in our computers. If even the smallest scratch got on a hard drive it could ruin it, and those suckers are running 24 hours a day in some houses.  It’s insane.

I love my DVD burner.

I’ve loved it for quite a while now, but, if possible, I think I love it even more now that I know how it actually works. A store bought DVD or CD is made up of billions of tiny bumps. When the laser in the player passes over the disc, the bumps reflect the laser back at a different angle than it does when the light hits a divot. A CD/DVD burner can’t create this, so burnable CD/DVDs are made up of an organic dye compound. When the dye gets heated it darkens, and the dark spots don’t reflect the laser back. So a DVD burner actually burns the DVD to get the information on it. Rewritable discs are even cooler. They’re made up of a compound that when heated and cooled crystallizes, but when heated to a higher temperature it doesn’t crystallize as it cools. This way, the disc can be written on and then burned back to its previous, empty state so it can be written on again.

Solid state drivers are the hardest for me to understand. In some sort of bizarre poetic justice, one of my camera cards decided to stop working on me this weekend. Being the inquisitve nerd that I am, I wanted to break it for reals and break it good. For being the size of a postage stamp, they’re surprisingly resilient. I eventually got two pairs of pliers out and snapped it in half, which ended up destroying any of the inside layers from which I could gleam any kind of useful information. Still, I present you a picture of the busted card, as a kind of delightful meta avant-garde piece.

So, in the simplest terms, solid state drives work by having a grid of columns and rows. At each intersecting point, there is a two transistor cell. In between the transistors is a thin oxide layer. . As long as the layers are linked through the oxide layer, the cell is considered to have a value of “1”. If you apply an electrical charge to the transistorsthe electrons drain to one of the gates and the oxide layer develops a negative charge severing the link, changing the value of the cell to “0”. Do this a couple of billion times and you can store yourself just about anything. The nice thing about solid state drives is that you can read, write or erase large amounts of data simultaneously.  There’s no read/write head that needs to find the data.

So if each one of the cells on the solid state drive represent a 1 or a 0 then each cell is equivalent to a bit of data. One byte is 8 bits. That picture of the busted picture card takes up 1,296,870 bytes or 10,374,960 bits. In the blink of an eye, the time it took for that picture to be processed, a small electrical charge was applied to ten MILLION cells on another memory card. That’s just staggering to think about. When you think about what these machines do all the time it’s hard to imagine that they’re as small and as cheap as they are.

My head hurts, I think I need to lie down.

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