The embedded system application is more and more widespread and is used in extremely many way. the type of chips is various . the file system widely uses in the embedded system, which causes the information and data sharing, and has realized the exchange of information with the computer system. In the commercialization operating system, it already has the file system, but the price is extremely expensive. We could obtain operating system that does not contain the file system. Considered from the above reason, we decide to develope the file system which needed. As an important constituent of the overall system, The file system has close correlation with the system and platform. Different system platforms use different drivers, and their file systems usually need the special realization.
Because entire file system itself is extremely huge and complex , I cannot introduce completely in the present paper. I will introduce several related modules that have been realized .
The paper implements the directory operating module of the FAT12 file system for the Philips LPC2214 chip。I analysed the FAT12 file system ,designed kinds of data struct,such as BPB data struct and directory data struct。In accord with the name rules and char sets，I implement the directory operating fuctions，include adding directory，deleting directory and so on，which strictly conform to FAT12 file system criterion.
