Selecting the Internal File System for your Device

The internal file system in your device controls access to ROM. The file system can also provide file storage in the object store, which is in RAM. Two internal file system options are available: the RAM and ROM file system and the ROM-only file system. These have different properties and you will want to select the correct one for your device. Both internal file systems provide the ability to mount additional external file systems, such as file allocation table (FAT).

The RAM and ROM file system provides file storage in the object store, as well as access to the ROM. The object store is the root of the file system, and all data under the root is stored in the object store, with the exception of external file systems, which are mounted as directories under the root. Data in ROM is accessible through the Windows directory. The RAM and ROM file system is most useful in devices that continuously power RAM because the object store is lost when RAM is not refreshed.

The ROM-only file system does not allow applications to place files in the object store. Data in ROM is accessible through the Windows directory, and external file systems are again mounted as directories under the root. Additionally, with the ROM-only file system, you have the option of choosing an external file system to be placed at the root of the file system. If you mount a file system as the root, all data below the root directory is stored in that file system, with the exception of other external file systems. The OEM has the option of leaving the Windows directory as read-only access to ROM, or of taking control of all files in the Windows directory. In that case, all paths under the Windows directory route to the root file system.

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