Android about RAM, ROM, SD card and various memory differences

RAM: Run-time memory. Equivalent to the memory storage of the PC, used to store various objects and variable constants when the application runs, the main role is to improve the speed of operation. Is the only memory that the data clears after a power outage.

Body Memory: Equivalent to PC hard drive. It consists of three areas: ROM, internal memory and external memory.

ROM: Read-only memory. This section of the file can only be read, non-erasable, such as the PC C drive below some of the system files are not deleted and modified. Used to store operating system boot class files. This part of the file is corrupted and will cause the phone system to fail to start and run. This zone file is not visible.

Internal memory: Used to store system files and apply private files. This section is generally not visible unless you have access to the root of the phone, and the data in it is not accessible unless you have permission and permission. Files such as application databases are stored here. The path is/data/data/package name/file, which is available through environment. Getdatadirectory (). GetPath () method gets.

External memory: This part of the space is the mobile phone connected to the computer after the display of the folder, the role of the same as the SD card. The path is generally:/storage/emulated，可通过Environment.getExternalStorageDirectory().getPath()方法获取。

SD卡：外置型拓展存储卡。一般指手机之外的存储介质，比如有的机型能支持两张此类存储卡（华为有的机型），有的不支持（小米有的机型）。路径一般为：/mnt/sdcard2等节点。

关于后两种存储路径，不同的机型可能会不一样，以后再详细讨论。

Android about RAM, ROM, SD card and various memory differences