[Coco] DECB directory question

[Robert Gault]

Mike Rowen wrote:
> I need help trying to understand the disk directory structure on track
> 17 and well the FAT structure. Just a SS 35 track disk.
>
> For a file entry, byte 13 contains the number of the first granule of
> the file. Is this number an index pointing to a specific byte in the
> FAT? I know that the FAT contains one byte per granule. So, for example
> let's say byte 13 for a given file entry is 06. Does this point to byte
> 06 in the FAT?
>
> Thanks,
> -Mike
>

Qualified yes. :)  The FAT is numbered BASE 0. That means you would look at the 
7th byte in the FAT as you count 0, 1, 2, 3, 4, 5, 6 to find the byte from the 
directory entry.
Depending on what you find in the FAT, you will know if 06 is the last GRAN, if 
there are more GRANs by following the number trail, or how many sectors exist in 
GRAN#6.