[hfs-user] Floppy formatting

Simon Bazley simon@eyeeye.com
Thu, 26 Sep 2002 18:15:41 +0100

The default block size is specified in Inside Macintosh: Files page 2-54 and 2-56.  It states that the default macintosh block size is 512 bytes.  Each device is conceptually a physical and logical device, the physical one being what in linux is a block
device (that happens to be a hard disk), logical one being on a per volume basis.  All Physical devices are 512 byte blocks, this is stated on 2-54, and discussed further in Inside Macintosh: Devices, SCSI Manager (3-12).
All code relating to the partition table, takes place at device level, rather than file system level.  This all changed with HFS+

I think the thing you're confusing is logical block size, which is stated as the lowest multiple of 512 such that less than 65535 blocks exist on the volume, and physical block size (always 512).
It states (2-54) that the organisation of a floppy disk doesn't include partitions (and hence can't include device drivers), wheras hard disks do.  Perhaps this has something to do with it.

This is all fairly academic if you're using HFS+ though, which I think sounds like the best idea.