a 64Mbit NOR flash memory chip. MLC is used to refer to cells that store 2 bits per cell, using 4 charge values or levels. A 2-bit MLC has a single charge level assigned to every possible combination of ones and zeros, as follows: When close to 25% full, the cell represents a binary value of 11; when close to 50%, the cell represents a 01; when close to 75%, the cell represents a 00; and when close to 100%, the cell represents a 10. Once again, there is a region of uncertainty (read margin) between values, at which the data stored in the cell cannot be precisely read. some solid-state drives use part of an MLC NAND die as if it were single-bit SLC NAND, giving higher write speeds. nearly all commercial MLCs are planar-based (i.e. cells are built on silicon surface) and so subject to scaling limitations. To address this potential problem, the industry is already looking at technologies that can guarantee storage density increases beyond today’s limitations. One of the most promising is 3D Flash, where cells are stacked vertically, thereby avoiding the limitations of planar scaling. In the past, a few memory devices went the other direction and used two cells per bit to give even lower bit error rates. Enterprise MLC (eMLC) is a more expensive variant of MLC that is optimized for commercial use. It claims to last longer and be more reliable than normal MLCs while providing cost savings over traditional SLC drives. Although many SSD manufacturers have produced MLC drives intended for enterprise use, only Micron sells raw NAND Flash chips under this designation. Triple-level cell A triple-level cell (TLC) is a type of NAND flash memory that stores 3 bits of information per cell. Toshiba introduced memory with triple-level cells in 2009. Samsung announced a type of NAND flash that stores 3 bits of information per cell, with 8 total voltage states (values or levels), coining the term "triple-level cell" ("TLC"). Samsung Electronics began mass-producing it in 2010, and it was first seen in Samsung's 840 Series SSDs. Samsung refers to this technology as 3-bit MLC. The negative aspects of MLC are amplified with TLC, but TLC benefits from still higher storage density and lower cost. In 2013, Samsung introduced V-NAND (Vertical NAND, also known as 3D NAND) with triple-level cells, which had a memory capacity of 128Gbit. They expanded their