For decades, the goal has been to create a random access memory (RAM) that is non-volatile like flash storage but retains the speed and addressability of a RAM chip. Such technology changes the way programs are compiled and executed.
The NAND flash memory used in solid state drives (SSDs) is non-volatile, and like a hard drive, data are written and read in large chunks (see
sector). RAM is much faster, and any single byte can be read, written, calculated, compared or copied independent of all the other bytes (see
byte addressable). However, RAM is volatile and loses its content when the power is off. See
storage vs. memory,
flash memory and
chips vs. disks.
Intel Optane for a While
Available from 2017 until 2022, Intel's Optane chips were an example of non-volatile RAM. Faster and more costly than the flash memory in SSDs, Optane was just not competitive (see
3D Xpoint).
A Paradigm Shift in the Future?
The interplay between main memory (RAM) and storage is how computers have operated since the 1950s. Software and data are copied to RAM "from storage," and updated data are copied from RAM "to storage." If storage were as addressable and as fast as RAM, the program and all processing could take place in storage. Computers would always be "instant-on."
However, that shift is likely to be decades away. Although non-volatile, byte-addressable RAM memories are increasingly used as caches and main memories in embedded devices, NAND flash storage chips are also getting faster, more dense and more economical. See
non-volatile memory.