This contains the full set of code you need to read and write files to secure digital cards in a way that is compatible with your PC.

A FAT16 filesystem layer is provided (no subdirectories or long file names right now).

Three different versions of secure digital block-level I/O are provided, from a slow and SPIN-only version to a reasonably quick assembly language version.

Read speed should be about 300KBytes/second and write speed should be around
150KBytes/second (or faster or slower depending on the card).

In these routines emphasis has been on keeping the code as short as possible.