How a Flash Drive Works
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Flash Basics
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DVDs, hard drives, floppy disks and nearly all other modern digital storage devices store data on spinning platters and read that data back off the platters as they spin. Flash memory is different: A flash drive has no moving parts at all. This makes it rugged, low-power, compact and portable. Because of this, flash memory is used for many different purposes from recording photographs on digital cameras to backing up computer files. Flash drives are the flash memory devices generally used to back up computer information.
Flash Structure
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At the center of a flash drive is a device called an EEPROM, or Electronically Erasable Programmable Read Only Memory. The EEPROM is an electronic grid. Wires called word lines flow in one direction, while bit line wires flow in the other. At every place where the two lines meet, there is a memory cell capable of storing one bit of information.
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Flash Functioning
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When the flash drive wants to store a bit at a particular place, it triggers the word line and the bit line for that location. This turns on a small electronic switch called the control gate. The control gate propels an electric charge past a thin barrier called the oxide layer to a second switch called the floating gate. The floating gate stores this charge until the flash drive sends a signal to reset it. Meanwhile, a cell sensor watches the floating gate. It records the value of the cell as a 1 or a 0 depending on whether or not the floating gate is storing a charge. The 1s and 0s stored by all the individual cell sensors together make up the data on the flash drive.
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