Micron is the latest NAND flash memory maker to announce plans for quadruple-level cell (QLC) flash memory, following similar announcements from Toshiba and Western Digital. It’s a very technical story with a very real impact.
NAND flash memory stores data in one bit per cell, with billions of cells in the flash memory chips. For flash drives to gain capacity, there are two solutions: increase the number of chips in the drive, which has physical limitations, and increase the density per cell, which is limited by the laws of physics.
The first single-level cell, with one bit per cell, first emerged in the late 1980s when flash drives first appeared for mainframes. In the late 1990s came multi-level cell (MLC) drives capable of storing two bits per cell. Triple-level cell (TLC) didn’t come out until 2013 when Samsung introduced its 840 series of SSDs. So, these advances take a long time, although they are being sped up by a massive increase in R&D dollars in recent years.