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Old February 11, 2013, 02:25 PM
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AkG AkG is offline
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Join Date: Oct 2007
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OK this is quick n its only kinda sorta right...ish. Good enough for gov'ment work. BUT dont take it as gospel...with lots more variables Im not gonna touch. ;)

SLC is Single Level....two states 0 or 1. Very durable, very fast at writes. Only one bit per cell.
MLC is MUlti Level...four states. Not as durable, fairly fast. Easy to mass Two bits per cell.
TLC is TRI Level...six states. More fragile, not as fast. Very cheap to make (50% less cells needed for X capacity compared to MLC). THREE bits per cell. It is unproven technology...and I personally am waiting a gen before ever opting for it as we have no idea on durability, etc. This is why I would never recommend a TLC based 840 std edition.

One of the reasons the big ones are so expensive is NAND density. Each gen of NAND is only a certain density per package / 'chip'. Going above that requires stacking (think MLC cell stacked on top of another layer of MLC cells)... Two layers is called dual die pkg. This is what is in 256GB models (usually...always exceptions). Sinlge layer is usually used in 128s (again with exceptions...etc etc etc).

Since that is the two most popular sizes with consumers (smaller drives usu less chips) is the most popular with mfg'ers of the drives (ie the companies who place the order with the NAND mfg'ers). Since that is what these companies mainly order....most production is geared towards it.

Since less is being costs more. Of course there is also the mega factor / bragging rights issue....and flagship models ALWAYS cost more.
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