Accessing the memory card of the DC

I wrote a small ### program for the DCLinux kernel 2.15 - I managed to d/l a file from the internet into a buffer in the DC RAM but I can't save it into the memory card I have because I don't have a clue how to access it. Can any one post me the C/ASM routines of how to access the memory card (for both output and input streaming).

thanx
Debby