... of a READ ONLY FATwhatever does not need a whole-sector buffer, and might fit within a kilobyte or two of code, so it MIGHT fit into a low-end '51 (I had such a FAT12/FAT16 implementation within an AT89C55, FAT32 is no different in this regard).

The gotcha is, it's a painfully slow approach.

However, there are ways how to use a FAT-formatted disk and NOT have to use a true filesystem. The most often used one is to put a fixed size file on a fixed position (e.g. the first one after having freshly formatted a disk or a card).

JW