Non-volatile memory is a form of persistent data storage that retains data while unconnected to a power source. Unlike RAM or any other type of main memory, which is closely connected to the central processing unit, non-volatile memory (NVM) does not have a direct path to the CPU. It’s much slower than main memory, but it stores more data. If data is running in main memory on a computer, it’s being immediately processed, but the moment the computer shuts down, all that immediate memory is gone. Non-volatile memory is much slower, and it stays on the corresponding hardware indefinitely without requiring a connection to computing power.
There are two types of non-volatile memory: electrically addressed and mechanically addressed. One of the most popular examples of electrically addressed NVM systems is flash memory. Flash memory saves large amounts of data without needing a constant connection to power. Flash drives use flash memory; they connect to another device using a USB port and store and modify data. Flash drives are very convenient because USB ports connect to multiple devices and can store large numbers of files. Examples of mechanically addressed NVM storage include disk drives and magnetic tapes.
The difference between non-volatile memory and NVMe
NVMe (Non-Volatile Memory Express) uses a PCI Express bus to read solid state drives and give them much closer access to the CPU, putting the stored data closer to main memory. NVMe was created by technology experts who wanted to speed non-volatile memory use. NVMe has more lines through which data can move from storage into main memory, which allows more data to cross that path at once. Though NVMe is a form of non-volatile memory, it’s only one type and is designed to run on solid state drives, not other hardware.