Flash memory controller: Difference between revisions

Revision as of 08:27, 12 October 2020

Revision as of 09:37, 30 December 2020

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{{Short description|Integrated circuit that interfaces flash memory to a host like a PC}}

[[File:Lexar USB stick 8 GB - Silicon Motion SM3253L-0309.jpg|thumb|Lexar USB stick 8 GB - Silicon Motion SM3253L - USB 2.0 single-channel flash controller.]]

A '''flash memory controller''' (or '''flash controller''') manages data stored on [[flash memory]] and communicates with a [[computer]] or [[electronic device]]. Flash memory controllers can be designed for operating in low [[duty-cycle]] environments like [[Secure Digital|SD cards]], [[CompactFlash]] cards, or other similar [[Data storage device|media]] for use in [[digital camera]]s, [[Personal digital assistant|PDA]]s, [[mobile phone]]s, etc. [[USB flash drive]]s use flash memory controllers designed to communicate with [[personal computer]]s through the [[USB port]] at a low duty-cycle. Flash controllers can also be designed for higher duty-cycle environments like [[solid-state drive]]s (SSD) used as data storage for [[laptop]] computer systems clear up to [[mission-critical]] enterprise [[storage array]]s.<ref name="kingston">{{cite web|title=Flash Memory Guide|url=http://media.kingston.com/pdfs/FlashMemGuide.pdf|publisher=kingston.com|accessdateaccess-date=7 March 2013}}</ref>

==Initial setup==

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{{Main|Garbage collection (SSD)}}

Once every block of a solid-state storage device has been written one time, the flash controller will need to return to some of the initial blocks which no longer have current data (also called stale blocks). The data in these blocks were replaced with newly written blocks and now they are waiting to be erased so that new data can be written into them. This is a process called ''[[Garbage collection (computer science)|garbage collection]]'' (GC). All SSDs, CF Cards, and other flash storage devices will include some level of garbage collection. The speed at which a flash controller will do this can vary.<ref name="OCZ_WA">{{cite web |url=http://www.oczenterprise.com/whitepapers/ssds-write-amplification-trim-and-gc.pdf |title=SSDs - Write Amplification, TRIM and GC |author= |date= |website= |publisher=OCZ Technology |accessdateaccess-date=2010-05-31 |archive-url=https://web.archive.org/web/20120526033947/http://www.oczenterprise.com/whitepapers/ssds-write-amplification-trim-and-gc.pdf |archive-date=2012-05-26 |url-status=dead }}</ref>

==References==