请教NVRAM 和 flash的区别是什么

cheneydong

请问哪位仁兄知道NVRAM 和 FLASH 在定义和功能上有什么不同，谢谢1

jsjjms

<P>NVRAM是一种内存管理模式，和flash不是一个概念。</P><P>你看一下手机里面的c盘，里面有nvram生成文件的格式。</P>

jsjjms

<P>NVRAM在磁盘上分出一片空间，然后当你使用这块空间的时候你需要使用mtk固定的接口，readvalue,writevalue,readrecord,writerecord。</P><P>你看看定义NVRAM的地方，有版本号，和一个英文字串的地方，那两个合起来就组成了nvram最后</P><P>存在磁盘里的文件的名字。nvram在定义的时候就必须知道空间大小，一开机这片空间就给你分好了。</P>

wangsamuel

虚拟ram, 其实就是flash,  这块东西用来存手机的固定设置值的, 不需要经常檫写

sunjams

同意楼上的说法。有特定的格式要求，除了用来存储手机的固定设置值外，还是协议存储参数的地方，如网络下来的配置参数，终端的一些协议参数配置。

zenglin1973

NVRAM: Non-Volatile RAM. The target is to have a electrical device that could be accessed quite fast, most of the time the content is calculated by bytes and the content could be saved after power down. There are different technical ways to implement this concept such as EEPROM which is very common. Please note, in mobile phone design, most of the time one or two sectors of ROM (most of the time it is FLASH) will be used to simulate NVRAM, the only reason is cost saving since ROM is a "must" but NVRAM is not.

FLASH: One kind of ROM and the difference to other ROM is semiconductor level. Please note, FLASH must be read/write by sectors but NVRAM should be read/write by bytes. It is why NVRAM driver have to implement an algorithm such as copying all the content in one sector to RAM first.

NVM: Non-volatie memory. It is more generic concept and covers all the memory components that could keeps its content after power off. It is useful during architecture design when the technical detail could be skipped. In fact, in one project, a DRAM with battery played as NVM and it worked quite good in that case.  [em02]

tritium

谁把上边这段话给翻译一下吧，看着好累！

nickyni

如果没有记错的话：
NVRAM实际上就是Flash，如果你的Flash是128Mbit的Spansion，那么NVRAM就有2MByte；如果是64Mbit，就只有1MByte；
NVRAM存放手机的一些默认值，比如默认Profile，默认Wallpaper，默认城市，Data Account等等参数

hanks

NVRAM是非易失的RAM，按RAM操作，
Flash则是根据种类，分别NOR或NAND接口操作