[comp.sys.amiga] What track is disk directory on 3.5" disk

IO00844@MAINE.BITNET (Zero Batzell) (12/06/90)

Forgive my ignorance since I'm new to the Amiga and it's 3.5" disks. But what I
 want to know is what track is the disk directory on? (I know that on a 5.25" d
isk it is located on track 18).  I'm also interested in any other information h
aving to do with the internals of a 3.5" disk.             Thanks  ((ZERO))

hgschmie@medusa.informatik.uni-erlangen.de (Henning Schmiedehausen ) (12/07/90)

In <90339.140949IO00844@MAINE.BITNET> IO00844@MAINE.BITNET (Zero Batzell) writes:

>Forgive my ignorance since I'm new to the Amiga and it's 3.5" disks. But what I
> want to know is what track is the disk directory on? (I know that on a 5.25" d
>isk it is located on track 18).  I'm also interested in any other information h
>aving to do with the internals of a 3.5" disk.             Thanks  ((ZERO))

GO BACK TO YOUR 64! :-)

No, sorry, I had to write it. The Concept of the Amiga is, that the 
Directory can be placed almost everywhere. Unlike the 64, Amiga-Disks
are divided in 'Blocks', there are 11 per Track, 80 Tracks, 2 Sides,
so there are 1760 of them. The Boot-Blocks (Blocks 0 & 1) are vital
to boot the machine, so they're no available to the normal user.
Normally, your Root-Block is the Block 880(This is exactly the middle
of the blocks, so you drive will access it faster). BUT IT NEEDN'T TO
BE THERE. You can place it all over the disk, because there is a 
pointer to this block in the root block. The real Directory-Organization
is A REALLY complex thing, from the root-block, there are pointers to 
the directory-blocks and from there to the Data-Blocks. And there are
also things like Bitmaps and Hash-Tables. If you really want to dive
deeper in the Amiga-Disk-Organization, you should buy the Commodore
Documentation manuals. They describe the disk organization in a very
good way. Ah, by the way, Amiga 5"25 Disks and Amiga 3"5 disks have
exact the same organization. So forget Track 18. :-)

					Ciao, see you in Cyberspace

								Henning


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