How a USB Flash Drive Works

By · Friday, October 8th, 2010

How a USB Flash Drive WorksDespite being the most popular form of storage transportation and data transfer, the USB flash drive remains largely unknown to the vast population of people who use it on a daily basis. Not many people know the extreme complexity of interworking components that it takes to send, receive, and store their data on a flash drive, but love to carry them around. Well today we are going to try to explain the internal components of a flash drive and exactly how they all work for you to store your important data.

Inside a USB flash drive there are several components that all must work together in order for your data to be sent or stored. The PCB board, USB mass storage controller device, and the flash memory chip are the 3 major components that make up a USB flash drive. Each component has its own function and each relies on the other in order to work.

The PCB or Printed Circuit Board is the backbone of the flash drive. This piece is where every other piece of the flash drive is plugged into and serves as connective pathways between each component. You might consider this piece of the flash drive to be similar to city highways system that allows information to flow between two points. Many PCBs are multi layered allowing information to travel between layers in route to their destination. This ensures that no pathways cross and data is obscured.

The next major component is the USB Mass Storage Controller Device. This system component is considered the brains of the operation as it tells the flash drive what to do. It communicates with the host device, such as a PC or any other USB device, and retrieves or send the desired information to the on board flash memory.

The last and most major component is the flash memory itself. This component is the part of the flash drive that actually stores your data. Flash memory is just another form of Electronically Erasable Programmable Read Only Memory (EEPROM), but with one exception, information can be erased one byte at a time instead of one bit at a time. For reference 8bits is equal to 1byte.

To complicate things, all information is stored in binary code in the form of 1’s and 0’s and it stores this information in using very small transistors. These extremely small transistors open or close to let a flow of electrons through each intersection. Each intersection has two transistors separated by a very thin Oxide layer and two gates. The control gate and the Flood gate are used as connectors between the two sections. If the control gate is given power, information is stored as a “1” in the flash memory and information is sent through the flood gate. If power is not given to the Control gate, information is stored as a “0” and now allowed to pass through the flood gate. Unfortunately as technical as the flash memory section of a USB flash drive sounds, it’s still much more technical.

So in a nutshell, exactly how does a flash drive work? Simplistically when you plug a flash drive into a USB port, the host controller will communicate with the host device let it know that it has been plugged in. A user then decides to retrieve or store information at which point device tells the host controller what to do. Depending on what needs to be done, information is then pulled from or stored to the flash memory.

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