Re: Copying Mac MFS disks on an Apple II

[mjmahon@aol.com (Michael J. Mahon)]

Jeff Blakeney wrote:

>On Tue, 02 Sep 2003 13:01:00 GMT, "M. Pender" <mpender@hotmail.com>
>wrote:
>
>>IIRC Mac HFS disk blocks are not the same size as ProDos disk blocks; there
>>are a few extra bytes thrown.  I doubt that the 512 byte ProDos blocks will
>>be very appealing to the Mac.
>
>ProDOS and HFS both used fixed block sizes of 512 byte blocks.  HFS+
>supports variable block sizes but I'm almost positive the smallest
>size they can be is 512 bytes and they must contain a number of bytes
>that is a power of 2 (ie. 512, 1024, 2048).

IIRC, the _actual_ physical block size on Mac floppies is 524 bytes.

The extra 12 bytes are used by the file system as "tags" to help
rebuild a broken directory, I think (I'm not a Mac person ;-).

-michael

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