🚀 go-pugleaf

I am running into trouble with my BIOS routine accessing floppy disk. Which
sector is the first sector for the file area on a 1.2M floppy disk?
Should it be sector 30 or sector 28? If I am not mistaken, boot record is on
sector 1, FAT starts at sector 2, root directory starts at sector 16 and is
14 sectors long. Therefor the file area, which should come after the root
directory, should starts at sector 30. However, my program didn't work with
that parameter. But when I change it to sector 28, it works fine so far
with no problem. Can anybody tell me how to calculate the starting sector
for the file area in any format of disk (both floppy and hard disk) during
run time?
 
This is very important and I would appreciate any help that I can get.
 
Thanks in advance.
 
-Amos Yung