I know that for some people on this forum using the name Elektor is very close to cursing, but anyway: a couple of months ago a Compact Flash interface + supporting software has been published. It's not a file system, but taken the fact that it's quite a job to make on a 805x it may be a good alternative, especially if you are only storing data. Retrieving the data may be quite a lot easier on a PC at a later stage.