The USB Drive

The USB drive, one of the more popular inventions ever created (you know, besides the wheel). We all have them, most of us even have a few dozen, since everyone seem to be giving them away lately.

They exist in all sizes and shapes but in the end they all word exactly the same. If you are interested to find out how? Well you came to the right place!

A USB drive uses a technology that I’m sure most of you have heard of. It’s called the Solid State or Flash memory. As I explained earlier, traditional media such as (older) hard drives and floppy disk drives (fossil!) rely on moving parts and magnetic fields to read, write and “remember” data. The solid state technology, which is used by the USB drive, uses only electrical current to write and erase data.

When data is written to the drive, the electric current alters the electronic components inside the USB key. This current will create a pattern that can be recognised and read by a computer. Since the USB key does not rely on moving parts it’s less likely to lose or damage the data it contains. I can hear you cheering because this sounds like the ultimate solution, a data storage device that doesn’t break or doesn’t lose data.

Sadly this is not the case, a USB drive can only be written on for a certain number of times. After that you cannot use it any longer. To avoid this problem a method called “wear leveling” is used. This process attempts to write data equally across the drive to prevent premature wear. But even with this process, the USB drive will eventually wear out.

This is how it works. Beware the explanation is somewhat technical.

The flash memory that we are talking about is in fact a type of EEPROM, if you have never heard of this. Don’t worry, this just means you have an actual life ;-).
EEPROM stands for Electronically Erasable Programmable Read Only Memory. A long name for what I explained earlier. Memory which can be altered by an electrical current.

If you want to follow this completely it would be handy if you have a USB key with a “see-through” casing. Or you could also demolish a broken USB key. If you don’t have a demolishable key, I’m afraid you’ll have to settle for a picture (and yes I, once again, snagged it from the internet).

Inside the USB drive you’ll find a small board (like a small motherboard) which is most of the time green. This board contains a series of components. The biggest 2 parts are the chips. 2 black squares. The first one if the flash memory controller chip and the second is the microcontroller chip.

The Microcontroller chip of the USB drive is a little bit like the CPU in your computer. This mini CPU synchronizes the input and output (I/O) operations. The memory chip is responsible for storing the data statically, this means it doesn’t need a battery or any other power supply to maintain the memory inside. How is this possible? (and trust me I had to look this up myself, because first I wanted to say “right, got it! Magic!”) Because of a technology called the Floating gate.
This technology makes it possible for the memory controller to trap electricity (translated to the USB drive, Data).

So far we’ve been talking about storing data and making sure the data is not released. But what about erasing data? As strange as it may sound. It works quite similar. The voltage flowing through the component changes and because of this the data is erased. Don’t worry, it won’t go changing itself, not will it ever shock you. The changes in voltage is determined by the computer in which you plug you USB drive.

You may have noticed that all of this happens in a very small amount of space. Which is quite amazing, specially if you know that the largest capacity USB drive(3.0 by the way) can store up to 1TB of data.

To give you a faint idea.. That’s 312500 mp3 files of 3.2 MB that is sitting in your pocket. Not bad? Right?


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