Flash drives have become a very popular medium for storing and transporting computer files, particularly USB flash drives. They are most commonly used for storing personal files such as documents, pictures, music, and videos.
Medical professionals use flash drives called MedicTags to store information that can be used in emergencies. System administrators may use flash drives to store configuration information that can be used for maintenance, troubleshooting, and recovery. A flash drive may also be used to boot an operating system.
The Inner Workings of a Flash Drive
The conventional USB flash drive is a combination of a NAND flash memory storage device and a universal serial bus, or USB connector. A USB flash drive can usually store between 64 megabytes to 32 gigabytes of storage.
Flash drives are non-volatile, which means that the information can be stored even when the device is not powered. Flash drives can be classified as Electronically Erasable Programmable Read-Only Memory, or EEPROM, which means that it can be erased and programmed in large blocks.
The drive contains a grid of columns and rows with a cell that consists of two transistors separated by an oxide layer. The first transistor is called the floating gate while other transistor is called the control gate. The floating gate is linked to a wordline through the control gate.
The Process
Tunneling is a process used to modify the arrangement of electrons in the floating gate. An electrical charge of usually 10 to 13 volts is applied to the floating gate from a column called the britline and then drains to the ground. This charge makes the floating gate act like a type of electron pump.
The charged electrons are pushed through the other side of the oxide layer, giving it its negative charge. The negatively charged electrons serve as a barrier between the control gate and the floating gate. A cell sensor then regulates the level of charge passing through the floating gate.
- If the flow has a charge higher than 50% of the original charge, it will have a value of 1.
- If it drops below 50%, it has a value of 0.
Flash drives are used in-circuit wiring to apply an electric field to specific sections on the chip called “blocks.” The targeted area can be erased from the chip an rewritten. This is how the data is stored and erased. A typical flash drive can be rewritten about 1 million times. The data stored on a flash drive can be retained for approximately 10 years.
