I've progressed quicker than I figured I would and have almost got files loading from it. It also supports directorys and will load a file from a full path+filename (just about). It only uses 8.3 filenames so far, but I suspect it will get expanded to do more in the future.
It takes arond 2k to add this although 600 bytes of it is data and a sector buffer. I suspect this will shrink a little once its all working properly, but to have fast access to 4Gb's of data is probably worth the extra space.
I also plan to put in a recursive directory search, allowing you to search for a game directory and then load from there. That means people won't be forced to put everything in the root directory.
I will also write a full Super CPU version allowing you to load megs directly into memory, and MUCH quick than a floppy could.