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Definition: MLC


(MultiLevel Cell) A NAND flash memory technology that stores more than one bit per cell. The original "single level cell" (SLC) flash memory uses one voltage threshold to define the two states of the bit (0 or 1). Multilevel cell (MLC) stores two bits in a cell (MLC), and triple level cell (TLC) stores three, which is accomplished by detecting four and eight voltage levels respectively (see below). However, the more bits per cell, the less longevity of the drive (see SSD write cycle). See NAND flash, StrataFlash and TRIM support.

Consumer MLC (cMLC) and Enterprise MLC (eMLC)
MLC generally refers to consumer MLC (cMLC), while enterprise MLC (eMLC) chips provide greater durability for servers, which handle huge volumes of reads and writes. Enterprise MLC drives feature faster transfer rates and extensive error detection and correction.

More Cells - From 2D to 3D
The multilevel cell technology doubled and tripled the bits per cell; however, moving from 2D single layer flash to 3D layers dramatically increased storage capacity (see NAND flash).


  Single Level Cell (SLC) - One Bit
          0
          1

  MLC and eMLC - Two Bits
  Mainstream flash memory.
         00
         01
         10
         11

  Triple Level Cell (TLC) - Three Bits
        000
        001
        010
        011
        100
        101
        110
        111




Triple Level Cells in 3D
These solid state drives (SSDs) from Kingston Technology use flash chips with triple level cells in a 64-layer 3D architecture (see NAND flash). See Mini PCI Express.