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Synchronous, asynchronous and toggle-mode NAND

Independent storage expert Marc Staimer discusses synchronous, asynchronous and toggle-mode NAND in this Expert Answer.

Can you compare synchronous and asynchronous NAND in terms of price and performance? And what is each typically...

used for?

Synchronous and asynchronous NAND, based on spec sheets, look remarkably similar in performance. However, they aren't, and the differences are non-trivial.

Synchronous NAND utilizes both the rise and fall of the signal wave to move data, giving it a potential of more than twice the performance than asynchronous (analogous to double-data-rate DRAM or DDR). Real-world numbers prove a much lower difference that ranges from 10 to 100% better performance depending on application.

Synchronous NAND is more expensive than asynchronous. Sync NAND is used when performance is everything, such as with gaming systems.

Also, what is toggle-mode MLC and what is it typically used for?

Toggle-mode MLC is asynchronous NAND that is supposed to provide similar performance as synchronous NAND, but at a lower price. Independent testing has not verified these claims yet. Toggle-mode MLC is also known as double-data-rate asynchronous NAND.

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