NAND Flash

NAND flash is a type of non-volatile flash memory that is widely used in storage devices such as solid-state drives (SSDs), USB flash drives, and memory cards. It is named after the NAND (NOT-AND) logic gate, which is used in its circuitry. NAND flash memory stores data in an array of memory cells, which are organised into blocks and pages.

Each block contains multiple pages, and data can be read and written at the page level. One of the key characteristics of NAND flash is its high storage density, which allows for large amounts of data to be stored in a small physical space. This makes NAND flash memory more cost-effective and compact compared to other storage technologies.

However, NAND flash also has some limitations, such as slower write speeds and a finite number of write cycles before the memory cells wear out.

NAND Flash Explained Simply

Picture NAND flash memory as a large, multi-storey car park. Each level of the car park represents a block, and each parking space within a level represents a page. Cars stored in the parking spaces represent the data stored in the pages.

When you want to retrieve a specific car (or piece of data), you need to go to the correct level (or block) and then find the specific parking space (or page) where the car is parked. When you want to write new data (or park a new car), you must first find an empty parking space (or page) within the desired level (or block).

If there are no empty spaces, you might need to clear out an entire level (or erase a whole block) before you can write the new data. This process of erasing entire blocks before writing new data is a characteristic of NAND flash memory, which contributes to its slower write speeds compared to read speeds.

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