Amiga Old File System: Difference between revisions

Revision as of 14:28, 15 October 2005

Revision as of 10:26, 28 January 2006

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The geometry of an Amiga Floppy Disk is as follows:

* DD disks: 512bytes512 bytes/sector, 11sector11 sector/track, 2track2 track/cyl, 80cyl80 cyl/disk

* HD disks: 512bytes512 bytes/sector, 22sector22 sector/track, 2track2 track/cyl, 80cyl80 cyl/disk

The DD disk has 11 * 2 * 80 = 1760 (0 to 1759) blocks, while the HD disk has 22 * 2 * 80 = 3520 blocks.

Amiga stores 880Kb880 KiB on a DD disk and 1760Kb1760 KiB on an HD floppy disk.

The standard Amiga filesystem has a internal 32 bit wide offset parameter (unsigned). It tells where to start the read/write operation. The biggest size for an Amiga disk is therefore 2^32 = 4 GBGiB. This limit was changed with Amiga OS 3.5 and 3.9 and now is 2^64 = '''4 Exabyte'''.

OFS Datablock stores Block Size BSIZE-24 bytes (i.e. normally 488 bytes at most frequently used BSIZE of 512 bytes), FFS stores BSIZE bytes (512 bytes per block).