Modifying Filing System (MFS)

An MFS is an extra layer between BASIC+ and the BFS. Typically, the MFS does not contain logic to access the physical file directly. Instead, the MFS simply monitors file activity, and then passes the file I/O requests, along with any data used for the request, on for further processing.

Because of its much more limited scope, an MFS is usually much simpler than a BFS. Whereas a BFS must in one way or another provide for all possible file I/O operations, an MFS can ignore almost all activity, and concentrate instead on the particular operation it is designed to monitor. An MFS must work in conjunction with the BFS that controls the filing system. A model for the relationship of an MFS to the BFS looks like: