[記憶體] DRAM寫讀次數問題

NAND RAM, SLC MLC果D, 大家都知有壽命問題

而一般D RAM, 常識黎講係無依種問題

而且亦都有人話不會壞的
http://we.poppur.com/thread-1666164-1-1.html

但我睇完反而懷疑
用電容就一定會充電次數問題
而且粒電容咁細, 可能一次read write就已經係一個完整的充電cycle
咁理論上, 條ram唔係會好快壞嗎?

dram終身保,如果係咁易壞,厰家傻的嗎?

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dram係volatile,同ssd,手指果d唔同.....

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呢度講得清楚D:
http://forums.anandtech.com/showthread.php?t=2211544

DRAM uses normal capacitors that are directly connected to the circuit and are constantly discharged and recharged. Solid state semiconductor capacitors don't really have any appreciable life cycle limit. Of course being ordinary capacitors, and very tiny ones, they drain and lose their contents in nanoseconds when unpowered.

Flash uses a floating gate transistor that permanently stores a charge in a totally electrically insulated floating gate that isn't connected to anything. Hot carrier injection or tunneling is used to force electrons though the insulator and into the floating gate at very high voltages where they are essentially trapped forever (until reprogrammed again) and electrostatically cause the non floating gate to be on or off depending on the content of the charge trapped in the floating gate. Thus representing one or zero.

The high voltage and tunneling of electrons through the insulator breaks down the dielectric insulator with each erase/program cycle as electrons tunnel through the material and change the molecular state and electron composition. Basically the high voltage tunneling poisons the insulator with free electrons (?) until the dielectric starts becoming a conductor and progressively leaking so much that the floating gate can no longer hold a isolated charge. It just conducts and drains instantly through the insulator when you try to fill it and can't ever be a "1" again.

The thinner the insulator (eg smaller die feature size = higher density) the less time it takes for the insulator to be destroyed, hence the declining write cycles with each process shrink.

In higher capacity and second and third generation SSDs it's no longer a concern due to the industry now understanding things like wear leveling, write amplication, etc. A device with 120 GB and 10,000 rewrite cycles would have to write 120 GB of data before each block had a write count of one, rince and repeat 9,999 more times, and you end up with decades of typical use.

裏面話DRAM只係普通電容,基本上唔會點損耗。

但flash入面嗰D係特別冇漏電電容,寫入時要用高壓打穿個絕緣層先可以寫倒落個cell度,所以寫得多會令個絕緣層漏電,跟住會hold唔倒個charge,咁就死咗個cell。

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RAM 有終身保,隨便用,隨便超吧

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任何野都有壽命, 只係長短問題

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咁你唔問下CPU???

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當然有限制, 不過講緊係一個天文數字的話, 邊個會理

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分分中長命過你

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當然有限制, 不過講緊係一個天文數字的話, 邊個會理
KinChungE 發表於 2014-9-24 17:23



我唔係在意果D電容有幾長壽命, 我只係在意點解佢地會有咁長壽命
又或者掉返轉頭, 用另一個角度去問, 點解有D咁強既差電技術, D電容廠, 差電廠, 仲唔將佢用係自已既產品上面?

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