[Coco] DECB directory question

[Mike Rowen]

Thanks for clearing that up for me. I need to look this all up in the  
Unravelled series.

-Mike

On Dec 20, 2010, at 1:42 PM, Darren A <mechacoco at gmail.com> wrote:

> On 12/20/10, 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?
>>
>
> If the file's first granule is 6 then byte 6 in the FAT will indicate
> whether or not there is a 2nd granule allocated to the file.  This
> continues in a kind of linked list fashion.
>
>> From Disk Basic Unravelled:
>
> A granule data byte, which has been allocated, will contain a value,
> which is the number of the next granule in the granule chain for that
> file. If the two most significant bits (6,7) of a granule data byte
> are set, then that granule is the last granule in a file’s granule
> chain. The low order four bits will contain the number of sectors in
> the last granule, which the file uses.
>
>
> Darren
>
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