Flash Memory Storage

So, what is flash memory? And how information is stored in it? Start with a memory. In layman terms, memory is such a box that selectively store or selectively retrieve the information. Like humans, Computer systems also have storage systems. They store data electronically, without it and without access to it, a computer is just a piece of junk box.

Different methods are devised to convert data into digital format. One of these forms is ASCII (American Standard Code for Information Interchange).

Capital "A" , “B” and “C” are stored in binary numbers as 1000001, 1000010 and 1000011 respectively.

Two types of electronic memory are defined: Volatile memory and Nonvolatile memory. In former data is temporary. Once the power is cut off, the data stored disappears. while in latter, information is preserved even there is no power running the system. Computer system cannot understand analog data, analog data refers to physical data like voice, radio signal, etc, they only understand digital data which has only two states 0 and 1 which corresponds to either ON state ie. 1 or OFF state ie. 0

A simple flash memory model consists of a storage transistor with a control gate and a floating gate, which is insulated from the rest of the transistor by a thin dielectric material or oxide layer. Source, drain and gate are three connections of a transistor.

Consider transistor as a water pipe, call one end of pipe as source which acts like a tap allowing the water to flow (in this case electric charges), drain is the other end of the pipe which lets water to flow out (in this case electric charges). Between source and drain is a pipe blocking called gate. When the gate is open, electric charges are allowed to flow and transistor stores one (1), when the gate is closed, flow of electric charges  is blocked and transistor stores zero (0). During the transistor is turned ON, some electricity leaks to the floating gate and stays there even when the transistor is turned OFF. This way information is protected even when the transistor is turned OFF.

References:

• https://www.quora.com/How-does-a-flash-drive-pen-drive-store-data
• https://computer.howstuffworks.com/flash-memory.htm
• http://www.explainthatstuff.com/flashmemory.html