Multi-level cell: Difference between revisions

Revision as of 14:47, 29 October 2021

Revision as of 14:49, 29 October 2021

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== Single-level cell ==

[[Flash memory]] stores data in individual memory cells, which are made of [[floating-gate MOSFET]] transistors. Traditionally, each cell had two possible states (each with one voltage level), with each state representing either a one or a zero, so one [[bit]] of data was stored in each cell in so-called ''single-level cells'', or SLC flash memory. SLC memory has the advantage of higher write speeds, lower power consumption and higher cell endurance. However, because SLC memory stores less data per cell than MLC memory, it costs more per megabyte of storage to manufacture. Due to higher transfer speeds and expected longer life, SLC flash technology is used in high-performance [[memory card]]s.

In February 2016, a study was published that showed little difference in practice between the reliability of SLC and MLC.<ref>{{Cite journal |title= Flash Reliability in Production: The Expected and the Unexpected |author= Bianca Schroeder and Arif Merchant |publisher= Usenix |journal= Conference on File and Storage Technologies |date= February 22, 2016 |url= https://www.usenix.org/conference/fast16/technical-sessions/presentation/schroeder |access-date= November 3, 2016 }}</ref>

A single-level cell (SLC) Flashflash memory may have a lifetime of about 50,000 to 100,000 program/erase cycles.<ref>[https://www.hyperstone.com/en/NAND-Flash-is-displacing-hard-disk-drives-1249,12728.html, NAND Flash is displacing Hard Disk Drives], Retrieved 29. May 2018.</ref>

A single -level cell represents a 1 when almost empty and a 0 when almost full. There is a region of uncertainty (a read margin) between the two possible states at which the data stored in the cell cannot be precisely read.<ref name="anandtech"/>

== Multi-level cell ==