How Flash USB Works - By: Steve Mc Karmik

Flash USB devices have become highly popular ways to store and transport data. They are simple to use, can be small enough to fit on a key ring and depending on the model can store up to almost 2 terabytes of information. Generally however most flash USB devices are around 2-30gb, but no doubt this number will increase.

Flash USB devices use ‘flash’ memory as the name suggests. This is a non-volatile form of memory meaning it won’t be erased if the power runs out, and can be deleted and reprogrammed but is read only (or technically EEPROM – electrically erasable programmable read-only memory). The way in which they work is not dissimilar from a regular hard drive and indeed in some cases they can replace the standard hard drive.

Flash memory is used largely for products that require low power to operate and that undergo harsh conditions. A flash USB memory stick meets just those requirements, being tossed about or stuffed in pockets and running off the power of the computer alone. Flash memory is also ‘solid state’ meaning that it relies on no mechanical parts and is purely electronic.

The exact mechanism of a flash USB device is rather complicated, but with a very basic understanding of computer science and electronics it is possible to grasp just the bare essentially of how memory can be stored. The flash memory chip works via a grid of rows and columns with two transistors separated by a thin layer of oxide at each intersection of the grid. Transistors have the ability to alter the strength of a current and this ‘grid’ of transistors then gives the device the capability it needs for ‘NAND’ memory. NAND refers to a type of ‘logic’ gate which is essentially a form of switch based on current that can be translated into binary code. In binary 1 represents ‘on’ and 0 represents ‘off’ and essentially this works via truth tables – where input = 1 & 0, output = 1 etc. In this way, information can then be stored as binary data within the grid.

This all takes place on a printed circuit bored (PCB) covered in plastic or rubber casing that gives it its durability. On top of the NAND flash memory chip, flash USB devices also consist of the male type-A USB connector, USB mass storage controller (which is its own tiny RISC processor) and a crystal oscillator. Some flash USB devices also include LEDs to indicate battery power etc. Others come with more complicated additional features and even have MP3 players and displays that allow you to view the files from the flash USB itself.

To use a flash USB memory stick you simply need to plug it into the USB port of your computer. From here most computers will recognise the flash USB and install the drivers which instruct it how to work with the new hardware. Really then we don’t need to understand anything more about how a flash USB works, and can just plug it in and watch it do its magic as the complex electronics inside mimic our brain in storing memories, ideas and information.

About the Author

No more of carrying the fragile floppies around; today flash drive technology has already threatened rewritable CDs with the ease and flexibility it offers. Do you own a memory stick or USB drive?

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